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SESSION 1 COAL GEOSCIENCES & RESOURCES-I

1-1

Affirming the Value of Coal in a Future Energy Portfolio: The Global Coal

Initiative

A.F. Armor, S.M. Dalton, EPRI, USA In choosing an optimum path forward for energy, particularly electric power, and recognizing the opportunities and pitfalls offered by each option in the full range of energy alternatives, it is impossible to ignore the major role still to be played by coal, our most pervasive and long-lasting fossil reserve. Coal has several hundred years of proven reserves, and is mined across the world in various forms. In burning coal, whether from bituminous, sub-bituminous, lignite, peat, or low-volatile anthracite deposits, the focus for the future is to eliminate harmful emissions, improve operating efficiencies, and find solutions to all equipment reliability issues. All these concerns can be handled by technology advances and should not be considered limiting in the long-term deployment of coal as a fuel. To preserve the coal option into the future, and to ensure that coal burning is accomplished in an environmentally conscious and profitable way, an EPRI Global Coal Initiative (GCI) is underway to build on and supplement worldwide coal combustion advances. With near-term goals to sustain fuel diversity and long-term goals to resolve the carbon/energy conflict and contribute to a sustainable energy future, the GCI involves a consortium of participants worldwide. Coal suppliers, coal users, equipment manufacturers, and industry /government consortia are working within the GCI to advance coal-fired power plant technologies and overcome current limiting issues. One aspect of the GCI is termed "Real Options". It has been increasingly difficult to make a business case for long-term, patient investments in coal in a world where short-term decisions are the norm and the national and international monetary value of technological options has been hard to quantify. The profits associated with energy transactions, however, can be readily quantified, and plant and equipment investments can be assigned a cash value. Investments in R&D can also be evaluated from a modern business perspective. To explore this, the "Real Options" project in the GCI is now applying an evaluation framework to provide a foundation for valuing technology choices. This paper will describe how this has resulted in new insights into the overall value of coal in power markets and an affirmation that coal is indeed a part of our future. 1-2

The Luebtheen Lignite Deposit in NE Germany: A Diatom Rich Raw

Material

Norbert Volkmann, Freiberg University of Mining and Technology Jochen Rascher, GEOmontan Entp. Freiberg, GERMANY

The Luebtheen Lignite Deposit is located in the NW part of Mecklenburg Vorpommern, about 22km (14 mi) south of Hyw. E26/BAB 24 Berlin-Hamburg (exit Hagenow). In upper Miocene, in this area the accumulation of organic matter has taken place into a crescent foredeep basin of a local salt dome. Drilling and geophysical surveying documented four seams with a thickness ranging from 2.5m to 35m (about 8 to 115 ft). The coal seams were formed in a paleoenvironment that was very much influenced by the salt dome. In fact, the accumulating organic matter interacted with the salt surface. As a result high salinity water has frequently changed the conditions of the depositional milieu causing an enhancement of silica solubility and explosively increase of diatom population. Under the view of Organic Petrology the Luebtheen coal can not be regarded as a common terrestrial lignite but as a highly detritic gyttja such like bottom sediments from recent lakes or ponds. The organic part of the layers consists mainly of liptinites, mostly sporinite and resinite. Cutinite and suberinous plant tissues (suberinite) occur only in accessorial content. All these components are allochthonous, transported from the surrounding mainland as pollen grains by wind or as tissue fragments by water. The limnic Bottryococcus sp. are the only autochthonous liptinitic components.Their body size and population decreased rapidly with increasing salinity and diatom content. In contrast submerse plants without any woody tissue are the source of the humic substances (humocollinite). Everywhere these textureless humic masses are in mixture with clay, quartz and amorphous silica from diatoms. Diatoms also produced a special Al-Fe-hydrophosphate with globular habitus, called Luebtheenit. This specific composition of the lignite formes an

ash/mineral content between 30 and 75% (wf.), that required technological modifications in the combustion process. On the other hand, the tar productivity is relative high (aprox. 17% wf.) and the sulphur content - a fact with high importance in ecology of raw material utilization - is extremely low. 1-3

Perspective of Chinese Coal Characterisation,

Li Wenhua, Jiang Ying, China Coal Research Institute, P. R. CHINA

This paper presents the brief introduction to Chinese coal characterization. Coal analysis methods and standards of China are introduced and a simple comparison is made between the coal analysis standards of China and ISO and other main coal production and consumption countries. The characteristics of different classes of coals, together with GB5751<<Classification of Chinese Coals, are described in brief. The information of “ database of China coal” is presented briefly. Moreover, the future four important fields in coal characterisation research are pointed out. 1-4

Review of coal quality variation in Late Permian Coal Measures of the

Bowen Basin, Australia

Hakan Kahraman, Joan S. Esterle, CSIRO, AUSTRALIA

Variations of technical characteristics are quite common in coal seams. This is usually a reflection of the original depositional conditions. It is quite common that original mire shape and geometry has a significant influence on the seam’s technical characteristics. The other influencing factors are original plant composition and chemistry, the proximity of distributary channels and crevasse splays, post depositional effects such as diagenesis and leaching, and finally primary rank factors such as temperatures and depth of burial. The coal seams within coal measures in the Bowen Basin are continuous for over 200 km along strike although the surrounding sediments change in lithofacies from terrestrial to marine along the strike length. However, the seams and splits are given different names in many of the mines. In the central portion of the basin, the sea level fluctuation resulted in a complex inter-fingering of the deltaic and marine deposits with coals. These depositional environment and geological changes are reflected within the coal seams. For example, it is interesting to note that German Creek formation, which was under the influence of marine environment, showed slightly higher content of sulphur compared to the Moranbah coal measures within the same group of coals (Group III). Also, Rangal coal measures are significantly different from the other coal measures in terms of their ash chemistry. Their phosphorus, Fe2O3, CaO, and K2O are notably higher than the other coal measures. These differences could be attributed to both original depositional environment and original plant chemistry and early coalification processes. In addition, the reflectance values from the German Creek seam ranging from 0.8% to 1.8% in the south indicate that the seam had gone through some burial and up-lifting processes during the basin’s history. It must be also noted that the Rangal coal measures were overlooked in terms of their coking ability in the past i.e. they were generally regarded as weak coking coals. However, as some of the Rangal coal seams have proved being some of the best coals available in the world for coke making, the coals from undeveloped deposits in Rangal measures still have potential to be used as coking coal. 1-5

The U.S. Geological Survey National Coal Resource Assessment

Brenda Pierce, U.S. Geological Survey, USA

The U.S. Geological Survey (USGS) National Coal Resource Assessment (NCRA) was a multi-year effort to identify, characterize, and assess the coal resources that will supply a major part of the Nation’s energy needs during the first part of the 21st century. Five priority regions were assessed: the Appalachian Basin, Illinois Basin, Gulf Coast, Illinois Basin, and Northern Rocky Mountains and Great Plains. The NCRA was a cooperative effort between the USGS and a number of State geological surveys in these coal-bearing regions. Complimentary studies of coal resources on Federal lands were also conducted. The purpose of the USGS NCRA was to (1) digitally assess selected coal beds and zones that will be the most important for mining during the next few decades, (2) create publically available stratigraphic, geochemical, and geographic information system (GIS) databases to answer a variety of questions of importance to government, industry and public decision makers, and (3) provide interpretive geologic and quality information for the primary coal resources of the Nation.

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Adequate energy supplies and the efficient use of those supplies are critical to the economic well being of a country. Information on affordable and reliable coal supplies is essential for the energy industry to meet the expected coal-based electric generation demands in the near future. Policymakers require a range of information on the energy supply, as well as the economic and environmental issues associated with that energy source and its use. Formulation of an effective national energy policy and development of energy resources requires that we understand the geology, distribution, quality, and size of the national energy endowment. The results the USGS National Coal Resource Assessment are important because they provide impartial assessment of the Nation’s coal resources. The USGS NCRA provides the information needed to effectively use these energy resources by (1) evaluating and minimizing the environmental impacts related to the extraction, production, and use of energy resources, (2) managing Federal lands, (3) addressing issues of energy policy, energy strategy, reliable and cost effective energy supplies, energy supply and demand analyses, land use management, environmental policy, energy security, economic projections, economic impact, and human health policy, (4) determining the potential for coalbed gas resources and development in the U.S., (5) determining the availability and recoverability of coal resources throughout the U.S., (6) determining potential areas of future coal development, and (7) assessing the potential of coal to act as a storage site to sequester carbon dioxide.

SESSION 2 GASIFICATION: MARKETS/PROJECTS-I

2-1

Worldwide Gasification Survey

Dale R. Simbeck, SFA Pacific, Inc., USA

SFA Pacific with the support of the United States Department on Energy (DOE) and the assistance of the major gasification vendors has developed a database of all the known worldwide gasification facilities. There are 163 commercial gasification projects with a total of 468 gasifiers. These gasifiers have a total synthesis gas (H2 and CO) capacity is 500 million normal cubic meters per day with an energy content of 67,100 MWth. If all this synthesis gas was converted to electric power it is equivalent to 37,375 MWe. This paper presents the worldwide gasification survey based on the database. The 163 commercial gasification projects are sorted and presented by technology vendor, project status, capacity, year of startup, location, feedstock and applications. This shown clear market trends and a major surge in worldwide gasification activities. 2-2

Advantage of Integrated Coal Gasification Combined Cycle (IGCC) Over

Other Advanced Generation Technologies and its Prospect in a Competitive Marketplace

Manoj K. Guha, American Electric Power Service Corporation, USA

With restructuring of the electric utility industry, and to meet the challenge of deregulation as well as customer demands for a free competitive market, the traditional roles of the industry will experience tremendous changes over the next few years. Because of the deregulation of the industry, there will be no guaranteed return on investment, but more importantly, the demand of customers for a free competitive market in the electric utility industry will force utility companies to achieve lowest cost for the commodity. Although low cost producers does not necessarily mean success, it is obvious that cutting and/or reducing capital expenditures will play the most important role to remaining competitive. The fundamental change due to deregulation may present both opportunities and challenges for the addition of new generation,including coal-based emerging technologies Unregulated markets encourage product diversity, as companies look for "niche" profit opportunities. A pervasive lesson from other industries that have recently been deregulated clearly shows that unless properly planned, these companies will not only do poorly but may be completely wiped out from the market. The electric utility industry will continue to face additional pressure from the proposed environmental regulations on SO2, NOx, VOCs, HAPs and above all CO2 emission reductions during the next ten years or so.While low cost utilities may have greater flexibility in adapting these changes to prepare for competition, they will be far from immune to the fast pace of industry changes. Under a fully competitive marketplace, all generating plant assets/investments will come out of rate base. Since all companies will be exposed to competition but will have to still satisfy all environmental

regulations, high cost and/or high emitting generation assets will be vulnerable. This will force the utility companies to invest in low capital cost and at the same time low emitting generation technologies only, at least during the next ten to fifteen years-----and for the electric utility industry, that means state-of-the-art natural gas combined cycle plant with advanced gas turbines. However, the recent price of natural gas (from $2.67/MMBtu in early 2000 to currently over $5.00/MMBtu, and in certain areas much higher than that), and concern about transportation constraints of natural gas are giving new incentives to coal-based generation. Coal as a primary energy source on the otherhand, is relatively abundant in this country and throughout the world and coal price has been relatively stable and projected to stay at or near present price for the foreseeable future. We believe that like in the past, coal will continue to be essential component for the long-term sustainable economic development, both in the United States and in many parts of the developing world. However, in order to maintain the potential for improved economic well-being, while simultaneously protecting the environment from excessive accumulation of anthropogenic (man-made) greenhouse gases and other pollutants (SO2, NOx, VOCs and HAPs including mercury), a technology-based transition is necessary. This transition will be driven primarily by more efficient generation of electricity, through the commercialization of technologies developed and demonstrated over the past two decades or so,combined with products of continuing public and private sector research and development (R&D) extending well into the 21st century. Clean Coal Technologies are intrinsically beneficial to the United States and to the third world countries because of abundant coal supplies. It is of paramount importance that the industry leaders and the government representatives continue to support the development, deployment and commercialization of efficient, environmentally compatible and economically competitive technologies based on life cycle cost rather than the first cost to allow the continued use of coal to fulfill this nation's demand for electricity and economic growth. This paper will briefly review the status of various advanced coal-based generation technologies with respect to their environmental performances, investment requirements (both capital and life cycle costs), market applicability and when and where these technologies are expected to be cost-effective and finally, how these technologies can compete with the state-of-the-art natural gas-fired combined cycle technology. We believe that as environmental regulations tighten on pollution especially with respect to CO2, SO2 and NOx emissions, advanced high efficiency Integrated Coal Gasification (IGCC) technology will have the best chance of penetrating the market at competitive price. It will also examine how an innovative concept utilizing IGCC technology could play an important role in penetrating the energy market on its own merit without any government subsidies. 2-3

Eastman Chemical Company, Kingsport Plant, Chemicals from Coal Operations: 1983-2001

Nate Moock, Eastman Chemical Company, AUSTRALIA

The Chemicals from Coal Facility of Eastman Chemical Company began operation in 1983 using various purchased technologies such as Texaco gasification and Linde AG Rectisol gas clean-up as well as Eastman-developed technologies for chemical production. Initially, the plant was designed to produce approximately 500 million pounds per year of acetic anhydride and acetic acid to supply half of Eastman’s acetyl raw material needs. The facility was expanded in 1991 and additional debottlenecking brought the capacity to the current level of approximately 1.1 billion pounds per year. Two Texaco gasifiers are campaigned to give gasifier system uptimes in excess of 98-99% with a maximum rate of approximately 150% of the original design. The facility is now the sole source of raw materials for Eastman’s profitable acetyl stream and is operationally and economically a proven means of producing acetyl chemicals from coal. 2-4

Clean Coal Technology Options – A Comparison of IGCC vs. Supercritical

PC Boilers

Richard C. Weissman, Texaco Power and Gasification, Dale Simbeck, SFA Pacific, USA

With the recent run-up in natural gas and other fuel pricing coupled with shortages of capacity, there has been renewed interest in new coal based power plants in the United States and elsewhere in world. Many coal based projects, utilizing clean coal technology, are being undertaken.

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An examination of clean coal technologies, specifically Integrated Gasification Combined Cycle (IGCC) vs. Advanced Supercritical PC Boilers will be presented. Relative operating factors, costs, and environmental performance will be compared. 2-5

Gilberton Early Entrance Co-Production Plant

Robert Hoppe, John Rich, WMPY, PTY, LLC, Gerald N. Choi, Nexant Inc.,

USA

Under the U. S. Department of Energy (DOE) "Early Entrance Co-Production Plant" Cooperative Agreement, WMPI, PTY, LLC is co-funding a project to assess the techno-economic viability of converting mixtures of coal and coal mining residue into premium transportation fuels with power as a byproduct. There are abundant quantities of coal waste scattered across the northeastern part of the United States generated, for the most part, during the heyday of the Industrial Revolution. Currently, efforts are underway to recover the energy available in these refuse piles and reclaim the land. Using coal waste not only provides a low-cost feedstock, but also removes a serious environmental legacy from the abandoned coal mines. The produced coal liquids will be superior to their petroleum counterparts in physical and emission properties, meeting and/or exceeding all current and expected future government fuel specifications. The WMPI team includes SASOL, Technology Ltd. (Fischer-Tropsch technology provider), Texaco Power & Gasification (coal gasification technology provider), and Nexant,Inc., a Bechtel Technology and Consulting Company, as the engineering management contractor. The project is being carried out in three phases. Phase I involves definition of concept and engineering feasibility study to identify areas of technical, environmental and financial risk. Phase II consists of an experimental testing program designed to validate the coal waste mixture gasification performance. Phase III involves updating the original design, based on results from Phase II, to prepare a preliminary engineering design package and financial plan for obtaining private funding to build a 5,000 BPD coal gasification/liquefaction plant next to an existing co-generation plant in Gilberton, Schuylkill County, Pennsylvania. The current paper will describe the project in some details, along with interim results from the Phase I engineering feasibility study which is currently in progress. 2-6

ISAB IGCC: Operation Record

L. Farina, S. Arienti, R. Domenichini, Foster Wheeler Italiana SpA, ITALY

Three major IGCC projects have been recently developed in Italy; two of them are in startup operation (API Falconara and SARLUX Cagliari) while the third one (Isab Energy Siracuse) is in now in commercial operation. The paper is focused on the ISAB Energy IGCC project, which entered commercial operation on april 2000 and overcame all the performance and reliability test within october 2000. The Plant processes refinery residues (asphalt) for the production of synthesis gas which, after proper treatment for pollutant removal, is fed to a combined cycle for the production of electric power. The net electric power production is 520 MWe. The gasification technology is Texaco hgh pressure quench. The gas turbines of the combined cycle are two Siemens 94.2. The paper will give a description of the plant and make a history of the startup period indicating difficulties encountered. The performance tests and reliability test results will be illustrated with the addition of information about the first year of operation.

SESSION 3

PULVERIZED COAL COMBUSTION-I

3-1 Effect of Pre-Drying on PF Combustion, Fly Ash and Emission Behaviour

of Different European Low Rank Fuels

Jörg Maier, Klaus R. G. Hein, University of Stuttgart, GERMANY

In various countries like Europe, Australia, USA, China, India and the former USSR moist fossil fuels such as lignites, brown coal and peat are one of the main pillars for power generation. If also in the future moist fossil fuels shall maintain their present share in the energy market, the development and realization of highly efficient energy conversion processes including a significant CO2 reduction will be necessary. The implementation of an external

pre-drying step with the use of a low temperature drying agent offers a plant efficiency improvement up to 5 % depending on the drying process. Therefore, the investigation of the consequences on drying, combustion, operation and emission behaviour by the implementation of a pre-drying process was the aim of a 3 year project (1998-2000) “Pre-Drying of Moist Fuels for Power Production”. It was partly funded by the European Commission and Industry. The Institute for Process Engineering and Power Plant Technology co-ordinated this project with partners from Finland, Poland, Greece, Romania, Bulgaria, United Kingdom and Germany. During the last years the author investigated the preparation, combustion, deposition, fly ash and emission behaviour of several European brown coals with and without pre-drying. For that the 0,5 kWth pilot scale fuel preparation and combustion plant was modified. The fuels, depositions and fly ashes have been characterised by standard methods and advanced methods such as ash fusion, laser diffraction, SEM-EDX, X-ray diffraction and petrographic analyses. The combustion process was characterised by in-flame measurements of flue gas temperature and flue gas concentration (NOX, O2, CO, SO2) along the combustion chamber and at the outlet of the chamber. The results show significant effects of the fuel and the pre-drying process on deposition, fly ash and emission behaviour. The particle distribution and the enrichment of minerals and elements is mainly influenced by the fuel ash, the mineral composition in the fuel and the combustion temperature. An increase of the combustion temperature by using pre-dried fuel correlates with increasing slagging and fouling problems, changes of the mineral structure of the deposits increasing SO2 emissions and a reduction of NOX-emissions by using primary measures. Further an improvement of burnout was analysed which could result in a reduction of the milling expenditure. 3-2

Thermodynamic Modelling of the Coal Ash Systems in Black Coal Utilisation (a new F*A*C*T database of the SiO2 -Al2O3 –CaO-FeO-Fe2O3

system and the effects of MgO, K2O and Na2O on liquidus)

Evgueni Jak, Peter C. Hayes, CRC for Coal in Sustainable Development, AUSTRALIA

A range of technological problems encountered in coal utilisation including ash slag flow, fluxing and blending in slagging coal gasifiers (IGCC), coal blending, slagging and fouling in PF etc are related to the melting behaviour of the coal mineral matter. These coal ash related problems are of major concern to many coal companies and electrical power utilities. A new thermodynamic database for the SiO2-Al2O3-CaO-FeO-Fe2O3 system has been recently developed to assist in prediction of the melting behaviour of the coal ash slags. This new database, in conjunction with the F*A*C*T computer package, is used to calculate the proportions of liquid and solid phases, liquidus temperatures and other phase equilibrium information that is important for prediction of melting behaviour of coal ash slags over a wide range of compositions, temperatures and atmospheric conditions. The new database incorporates the latest experimental data, and uses the most advanced thermodynamic models of the oxide phases available. The model development involved the systematic thermodynamic optimisation of the whole five-component SiO2-Al2O3-CaO-FeO-Fe2O3 system. This optimisation has significantly improved the accuracy, reliability and range of applicability of the model. The paper will describe the systematic analysis of phase equilibria in coal ash slag systems and will provide important information for solving a range of technological problems. The effect of the iron and calcium oxides on the proportions of the liquid and solid phases will be presented in graphical form. The effect of SiO2 to Al2O3 ratio in the coal ash slags will be analysed. Predictions of the stability of the slag and mineral phases as a function of temperature will be given. Results for the oxidising and reducing gas atmosphere will be reported. The systematic analysis of phase equilibria in the coal ash slag systems presented in the paper will provide information for the coal utilisation researchers and engineers important for a range of industrial applications [1-7]. The work outlined in the paper has been undertaken as part of the Collaborative Research Centre for Black Coal Utilisation, Newcastle, Australia.

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3-3

A High Efficient Combustion (NR-LE) Method for Lignite Firing Units

Pauli Dernjatin, Fortum Power and Heat Oy, Kati Savolainen, Yoshitaka Takahashi, Miki Shimogori, Hirofumi Okazaki, Fortum Engineering Ltd,

FINLAND

During last ten years Fortum company have been very active in the field of developing low NOx burners for coal firing power plants including both tangential firing and wall/opposed firing technologies. The origin of the wall firing burner technology is from the Japanese company Babcock Hitachi K.K. and it is a licensed product. Technology for tangential firing units is based on Fortum's own R&D activities. At this moment we are expanding our activities to lignite Most lignite coal firing units in Europe are equipped with tangential firing combustion system where flame is stabilized in the central fireball instead of individual burners. Normally lignite has high moisture content (20 - 50 %) and high ash content. Because of the high moisture content, lignite firing boilers are equipped with special drying and grinding system. For grinding the hammer type or fan type of mills are normally used and for the drying instead of air, the mixture of hot flue gases (800-1000 oC) and air are used. Because of high amount of hot flue gases and only low amount of air are used for drying of lignite, the O2-content of the carrier gas of lignite, is low. Typically the O2-content of the carrier gas is 8-15 %, which is significantly lower compared to bituminous coal firing systems. The final moisture content of lignite after drying is about 7-12 %, which is also higher than bituminous coal firing units. Low O2-content of carrier gas and high moisture content of fuel has negative effect on coal ignition causing low combustion efficiency and high NOx-emission. Existing lignite firing units applies very simple burners, which are actually not burners but coal injectors. This means that lignite coal ignites very far from coal nozzle, normally after 2-4 m from the nozzle in the central fireball. And because the oxygen content of the carrier gas is low, the ignition and flame stabilization is poor. This causes narrow operation range for boilers, typically 60-100 % and in the low load operation it is necessary to use oil or gas for flame stabilization and for safe boiler operation. Today also lignite firing units have to change their operation mode from "base" power producers to "regulatory" power producers. This means that power plant have to increase the boiler load range from existing 60 - 100 % to 30 - 100. This target it is not possible by applying the conventional lignite burners. This is the reason, why Hitachi and Fortum decided to develop a totally new concept for lignite firing, including new type of low-NOx-burners named as NR-LE-burners (NOx Reduction - Load Extension) applying "high temperature" philosophy. The basic feature of this new combustion system is the stable flame, which makes it possible to reduce the boiler load. At the same time NOx emissions are reduced significantly, because a substoichiometric zone is formed very close to the burner tip, and the two-stage combustion is carried out by means of a single burner. This single burner staging technique combined with staging in the main vortex with OFA is very effective in lowering NOx emissions, combining the advantages of swirl-stabilize combustion In order to develop NR-LE-burner and to finalize the burner structure of new lignite burner, three months combustion tests were carried out in Japan using Babcock Hitachi's test rig at Kure Works. For the combustion tests 100 ton typical Eastern European lignite was shipped from Czech Republic to Japan. First demonstration of the new combustion system will carried out in Czech Republic in the summer 2001. The commissioning of the new combustion system starts in the September 2001. 3-4

Combustion of Coal Blends

Philip Bennett, CoalTech Pty Ltd, AUSTRALIA

The increasing growth of the world thermal coal market is seeing more producers from Australia, Indonesia, South Africa, Colombia, China, USA and Canada entering this market. Blending is being considered by some power generators to reduce variation in coal quality to the boiler thus allowing diversity of supply and, in some cases, the ability to fire local coals. The understanding of the combustion performance of blends is important to determining the economical benefit of blending. The combustion performance of a blend dictates the level of carbon in the ash, with high carbon-in-ash equating to energy losses and increase ash disposal costs. NOx emissions are also influence by the combustion performance of the blend. The combustion performance of a coal

blend is more complex than that of a single coal because it is not only dependant on the combustion performance of the component coals but also on the interaction between these coals. This interaction between coals first occurs in the milling of the blend where there is potential for large differences in the size distribution of the component coals, especially if there are large differences in the hardness of each coal. Using pilot scale test work conducted in Australia and overseas, this paper focuses on how the milling behaviour of a blend influences the combustion performance of a blend. It is through the understanding of the grinding of each component coal of a blend that it is possible to estimate the carbon-in-ash of a blend. The influence of other coal properties, such as pyrolysis yield and char reactivity, on a blend's combustion behaviour are also discussed.

SESSION 4 LOW-RANK COAL UTILIZATION-I

4-1

CAMD Study on the Change in Physical and Chemical Properties of Coal

along with a Progress of Moisture Release

Haruo Kumagai, Kouichi Miura, Kazuo Nakamura, Tadatoshi Chiba, Hokkaido University, JAPAN

The effects of moisture release on the conversion reactivity can be due to an irreversible change in the coal structure such as collapse of pore result in a limitation of accessibility of reacting components. A computer-aided molecular design (CAMD) method was utilized to evaluate the change in the physical and chemical properties of brown coal along with a progress of moisture release. The calculated molecular conformation of brown coal showed a deformation of the shape with a decrease in the number of water molecules interacting with the coal model molecule. It was found that the hydrogen bonding and electrostatics interaction play a relatively important role in formation and stabilization of the structure of the model molecule as well as interactions between the model molecule and water. Removal of water molecules results in a drastic change in the density of cell which contain coal model molecules and water molecules at the final stage of moisture removal. This indicates that the dense conformation of the coal model molecules with water molecules changed to porous one at the final stage of moisture removal. Size distribution of pore stuffed with water molecules shifted slightly toward a smaller radius up to 80% of moisture removal. Then, the distribution became broader and mean pore radius increased from extent of moisture removal of 80%. This increase in mean pore radius well corresponded to the change in the density of cell. The results appear to represent the characteristics of the brown coal, at least change in the density and pore size distribution along with a progress of moisture release. 4-2

Study on Aggregation States of Coal Molecules at Solid and Solution States

Masashi Iino, Hengfu Shui, Koyo Norinaga, Tohoku University, JAPAN

The effect of tetrabutylammonium acetate (TBAA) addition on the aggregation of the pyridine insoluble extract fraction, PI, from Upper Freeport coal at solution and solid states was investigated. About 30 wt% of original PI (PI-0) was insoluble in the CS2/NMP mixed solvent. While, PI-0 was almost completely soluble in the mixed solvent containing a small amount of TBAA. After the removal of CS2, NMP, and TBAA from the solution, PI was recovered with little mass loss. The recovered PI (PI-1) was found to become almost completely soluble in the mixed solvent and NMP even in the absence of TBAA, although the elementary compositions and IR spectra of PI-0 and PI-1 indicate that their chemical structures were identical. XRD patterns observed for PI-0 and PI-1 suggest that PI-0 has more aggregated and oriented structures than PI-1. PI-2 or PI-3, which were obtained by the removal of the solvents from PI-1 solution in the mixed solvent or NMP without TBAA, was found to become again partly insoluble in the both solvents. This can be explained by the increased aggregation of PI during the removal of the solvents, contrary to the solvents procedure from PI-0 solution with TBAA, in which TBAA seems to act as an aggregation inhibitor. 4-3

Degradation and Extraction of Brown Coal by Sub-Critical Water

Nao Kashimura, Jun-ichiro Hayashi, Tadatoshi Chiba, Hokkaido Univ, JAPAN

Brown coals contain water as much as 30 - 60 wt-% on a wet basis, and hence the energy required for drying the coals prior to conversion corresponds to 4 - 14 % of their chemical energies after dried. Thus, the drying inevitably causes the

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reduction of energy efficiency of the conversion processes. Conversion of coal in sub-critical water, if possible, has advantages of utilization of inherent water without drying. In the present study, extractability of a brown coal, Loy Yang, into sub-critical water was examined in the presence and absence of an alkali salt, Na2CO3. The extraction was performed in a flowing-solvent reactor, in which solvent was forced through the bed of coal particles. The reaction conditions were as follows: heating rate; 20 K/min, holding temperature; 473 – 623 K, holding time; 0 – 90 min, solvent; pure water or aqueous Na2CO3 (0.0001 – 0.1 N) solution, solvent flow rate; 1.0 ml/min, pressure; 24 MPa. The extraction yield was determined from the relative mass of residue to that of coal on a dry-ash-free basis. The extraction by pure water gave the yields of 0.41 and 0.65 at 473 K and 623 K, respectively. These yields were greater than those attained by using a non-hydrogen-donor solvent, 1-methylnaphthalene, at corresponding temperatures. Considering that sub-critical water is a less powerful than 1-methylnaphthalene for dissolution of the coal, the result strongly suggests progress of degradation through reactions such as hydrolysis, which is possible due to enhanced ionic product of water at sub-critical state. The degradation was evidenced by promotion of extraction in the presence of Na2CO3. At both temperatures of 473 K and 623 K, the extraction yield increased with an increase in the concentration of Na2CO3, which is expected to catalyze hydrolysis of etheric linkages abundant in the coal. Nearly complete extraction was realized when the Na2CO3 concentration was 0.1 N even at 473 K. The results of this study lead to a possibility of a process combining the dissolution of brown coal and further conversion of the dissolved material into gases such as CH4 over catalysts such as Ni in sub-critical water. 4-4

Mechanical Thermal Expression – Effect of Kneading Coal Prior to MTE Processing

George Favas, A. L. Chaffee, T. Kealy, Monash University, C. Tiu, CRC for

Clean Power from Lignite, AUSTRALIA

Mechanical Thermal Expression (MTE) is an energy efficient dewatering technology that utilises low temperature and a mechanical force to squeeze the water out of coals with a high moisture content. The major advantage of this process is that a significant amount of water can be removed from the raw coal at relatively low temperatures (below 200°C). The very high solid coal recoveries, the low organic content of the waste water and the ability to remove troublesome inorganic constituents, in particular sodium, are additional favourable features. Optimising processing conditions in a small batch unit is the first step in understanding the mechanisms and must be attempted before scale up of the process can be effectively implemented. One aspect of processing conditions that has been little studied is the effect of kneading coal prior to MTE. Raw Latrobe Valley coal was kneaded for various times (1 – 105min) and then processed in a small MTE batch unit at various pressures (4 to 12MPa) and temperatures (125 - 180°C). Kneaded coal gave a product of higher moisture content and higher large pore volume than unkneaded coal. The effect of increased temperature and pressure were the same for kneaded and unkneaded coal. An increase in mechanical pressure from 4MPa to 12MPa was found to increase the density and decrease the porosity, decrease the moisture content and also increase the carbon content of the coal. The applied mechanical pressure was more effective than temperature in producing an upgraded product. 4-5

Characterisation of Organic and Inorganic Components in Product Water

From a Novel Lignite Drying Process

Ying Qiand, Alan L. Chaffee, Monash University, AUSTRALIA

Due to its high moisture content (up to 70%), lignite in Victoria, Australia must be partially dried prior to combustion. Current coal dewatering technologies, based on evaporation, consume large amounts of energy since the latent energy of vaporization must be expended. The non-evaporative Mechanical Thermal Expression (MTE) technique has been investigated and shown to be a promising method for future application. During the MTE process, a wastewater stream, containing both organic and inorganic impurities released from the coal, is produced and thus has a potential environmental impact. Knowledge of the nature of this product water is very important considering the influence of processing conditions on types and amounts of chemical species present in the water and the selection of future waste cleanup approaches. This paper focuses on characterization of organic and inorganic components in MTE product water as a function of processing temperatures and pressures. A series of lignite types are MTE treated under similar conditions. Gas chromatography - mass

spectroscopy (GC-MS) is used to identify major organic components. Elements, such as calcium, sodium and magnesium, are analyzed using atomic absorption spectrometry (AAS) and inductive coupled plasma atomic emission spectrometry (ICP-AES). The results show that the amount of organic and inorganic constituents present in product water was affected by processing pressure, temperature and lignite types. A significant portion of sodium is released to the water during the process. This result could be beneficial as the sodium content in coal is closely related to fouling problems during coal combustion.

SESSION 5

GREENHOUSE GAS CONTROL & CO2 SEQUESTRATION-I

5-1

Modeling of Gas Adsorption on Coals

K. A. M. Gasem, J. E. Fitzgerald, Z. Pan, R. L. Robinson Jr., Oklahoma State University, USA

Gas adsorption data are essential in enhanced gas recovery from coalbeds. Coalbeds contain adsorbed methane, which is in a denser phase than conventional natural gas. Nitrogen and carbon dioxide (CO2) injections are potentially useful in coalbed methane enhanced (CBM) recovery. However, knowledge of the competitive adsorption of methane, nitrogen and CO2 on coalbeds is required to elucidate mechanisms for the recovery process. In addition to the energy-supply benefits of CBM, the injection of CO2 into coalbeds has received special attention because of the potential environmental benefits of sequestering a greenhouse gas. Efforts are underway to improve the equation-of-state (EOS) framework for modeling equilibrium gas adsorption of CBM processes. Our current focus is on evaluating and further developing the predictive capability of the combined simplified-local-density / Peng-Robinson (SLD-PR) model for supercritical adsorption systems of the type encountered in CBM recovery and CO2 sequestration. Such developments are aiming to facilitate the use of highly efficient EOS computational frameworks for representing adsorption behavior, as well as improving our understanding of the phenomenon. The abilities of the SLD-PR model to correlate accurately supercritical adsorption systems of the type encountered in CBM recovery and CO2

sequestration are demonstrated using the newly-acquired measurements on activated carbon, Illinois-6 coal, and our previous data on Fruitland coal. The results indicate that our modified SLD-PR model, which incorporates an improved repulsive parameter ‘b’ for the Peng-Robinson EOS, is capable of modeling the adsorption of methane, nitrogen and CO2 at coalbed conditions. Calculations based on a flat-surface and slit adsorption geometries yield results superior to our ZGR 2-D EOS model for the adsorbates considered. Predictions within 5% average absolute error have been realized from both models. This study concludes that proper accounting of coal heterogeneity and structural complexity within the SLD-EOS framework is effective in improving our modeling capability of high-pressure adsorption phenomenon. Further, (a) the model generates direct estimates for the adsorbed-phase densities, which facilitate reliable prediction of absolute gas adsorption; and (b) it readily describes the maximum observed in Gibbs-adsorption isotherms CO2 at temperatures and pressures encountered in coalbeds. 5-2

4-D Coal Permeability for Geological Sequestration of CO2

Mr. Paul Massarotto, Dr. Victor. Rudolph, Dr. Sue Golding, Dr. Miryam

Glikson The University of Queensland, Australia

It is well known that CO2 adsorbs unto coal’s internal microstructure on a preferential +2:1 basis compared to methane. It is also known that methane desorption is a strong function of the partial pressure to methane, so that carbon dioxide and even nitrogen can be used to coax the methane out. Key technical parameters affecting the economic viability are the injectivity of CO2 and flue gases, and the productivity of produced methane; both are determined by the bulk coal reservoir permeability and its variance over time. A joint Chemical Engineering & Earth Sciences project at The University of Queensland is investigating the absolute, effective and relative permeability of in-situ coals, under realistic conditions of stress and pore pressure, utilising a

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world-first True Triaxial Stress Coal Permeameter. This paper summarises the 4-D nature of coal permeability and the research program to arrive at the requisite knowledge of the behaviour of in-situ coals to CO2 injection: measuring the effective and relative permeabilities of the CO2 & CH4 system, and the displacement efficiencies on methane-saturated samples. Also, comparisons are made between utilising pure CO2 and a mixture of CO2 & nitrogen, on the feasibility economics of utilising such a process in Australia. The kinetics of competitive adsorption and desorption, of Fickian diffusion and the geochemical and geomechanical injection-induced alterations, are investigated as to effect on the main Darcy flow of the cleat system. Added insight is provided by petrological characterisation of potential coal sequestering reservoirs. Some preliminary results are presented on the anisotropic behaviour of permeability and the importance of considering the correspondence principle between directional stresses and cleat orientation. 5-3

GEODISC Research: Carbon Dioxide Sequestration Potential of

Australia’s Coal Basins

Barry E. Bradshaw, John Bradshaw, Glenn Simon, Victoria Mackie, Australian Geological Survey Organisation, AUSTRALIA

The Australian Petroleum Cooperative Research Centre’s GEODISC program is a collaborative research program examining the technological, environmental, and commercial feasibility of geological sequestration of CO2 in Australia. The 4-year program is being funded by the major LNG producers in Australia and the Australian Greenhouse Office. Emissions of anthropogenic CO2 have increased by over 15% in the last 40 years, and there are demands for developed countries such as Australia to either reduce or sequester greenhouse gas emissions. About 41% of Australia’s annual anthropogenic greenhouse gas emissions come from 50 stationary energy sources. These point sources are predominantly coal-fired power stations supplying energy to the mainland capital cities and major industrial areas. The GEODISC program has identified sedimentary basins in Australia close to anthropogenic CO2 sources that contain Environmentally Sustainable Sites for Carbon dioxide Injection (ESSCI’s). Potential geological sequestration options include use of CO2 in enhanced oil recovery, injection into depleted oil and gas fields, storage in unused saline formations, injection into deep unmineable coal seams, and for enhanced coal seam methane production. Australia has over 300 sedimentary basins, 50 of which proved to be viable study areas for potential ESSCI’s. Many of these basins contain coal seams that may be capable of sequestering CO2. Several of these coal basins occur close to coal-fired power plants and oil and gas fields where high levels of CO2 are emitted. The potential for coal seams to sequester CO2 can be determined by assessing five key parameters: storage capacity, injectivity, containment, existing natural resources, and site economics. The most suitable basins include the Bowen Basin in Queensland, and the Sydney, Gunnedah, and Clarence-Moreton Basins in New South Wales. The thick, continuous, high rank coals from these basins have the potential to store large volumes of CO2 (total risked storage capacity ~1-8Gt depending on recovery of in place resources). Injecting CO2 into coal seams from these basins also has the potential to substantially increase any future production of coal seam methane and thus make geological sequestration economically attractive. Saline aquifers and depleted gas fields from the same basins have a similar large storage capacity (risked storage capacity ~6 Gt). However, these sequestration options do not presently have the additional economic benefits of CO2 injection for enhanced coal seam methane production. There are several key risks associated with geological sequestration into coal seams that need to be addressed at any potential sequestration site. In particular, any potential injection site needs to be deep enough (generally >800m) to ensure that future coal resources are not sterilised, but shallow enough (generally <1200m) to ensure that coal seams are sufficiently permeable to allow CO2 injection and coal seam methane production. Good injection rates are anticipated to be in the order of ~0.05 Kt/day per well, while high injection rates of ~0.16 Kt/day per well may be possible in some sweet spots. Small black coal fired power stations (which account for 1% of Australia’s total greenhouse gas emissions) emit CO2 at rates of only ~ 0.5-2 Kt/day, which would require between 3-40 injection wells if good to excellent injection conditions are present. Potential sequestration sites for such small-scale emissions would currently be limited to established coal seam methane fields in the Bowen Basin (Fairview and Dawson River). Larger black coal fired power stations (which account for 23% of Australia’s total greenhouse gas emissions) emit CO2 at rates of between 3.4-46 Kt/day, which would require between 20-920 injection wells even if good to excellent injection conditions are present. Such large-scale injection operations are currently problematic given the limited locations where permeable coal seams have been identified. However, future growth in the

Australian coal seam methane industry and advances in technologies and innovation for enhancing permeability in tight coal reservoirs may ultimately lead to CO2 emissions being sequestered into coal seams in these basins on a larger scale. 5-4

Hybrid Coal and Gas Turbine System Development for Mitigation of

Greenhouse Gas at Coal Mines

Michael N. Wendt, Andrew C. Beath, Cliff W. Mallett, CSIRO Exploration and Mining, AUSTRALIA

The perception of coal mining as a major greenhouse gas and waste producer threatens the sustainability of the coal industry. To help overcome this problem a pilot-scale demonstration is underway of a new hybrid coal and gas turbine power generation system that has the potential to completely mitigate methane emissions from coal mines. The use of coal mine methane in Australia is hampered by geography and the nature of its supply. The methane is produced in streams that have large fluctuations in both concentration and flowrate. Almost 2/3rd of the methane released from Australian underground mines is from the ventilation air system of the mine and has a concentration below that required for self-sustaining combustion. In addition, the gas quantity is relatively small and power generation systems struggle to compete on economies of scale with large-scale coal fired power stations. The gas is a long distance from industry and significant population centers and there is almost no pipeline infrastructure to transport the gas. The system presently under prototype development is a hybrid gas and coal system which uses a kiln to burn a mixture of waste mine gas and waste coal. The kiln provides sufficient residence time at high temperature to burn low concentration methane. The waste coal is also used as a supplementary fuel to even out the variation in concentration. At times of low gas production the system is designed to run completely on waste coal. Both coarse and fine reject waste materials can be used together with fugitive methane emissions to produce electricity and other valuable byproducts such as lightweight expanded aggregate. “As mined” material can be used directly in the kiln or the waste can be preprocessed to allow the production of a lightweight aggregate material suitable for the production of lightweight concrete or bricks. The efficient utilisation of coal mining waste streams are part of a targeted effort to become a zero emission-zero waste mine. In addition to mitigating methane emissions from the ventilation systems, emissions from the spontaneous combustion of waste coal stockpiles can also be reduced. The maximum greenhouse benefits can be achieved by using not only the drained gas from the mine, but by sizing the plant to use all of the ventilation air as well. For a typical gassy mine, with a 200 m3/s airflow, this equates to a powerplant with a 100MW capacity. Instead of conventional power generation via a steam turbine system, an externally fired gas turbine system is under development. In this system, the combustion chamber of the gas turbine is replaced by a heat exchanger which recovers the heat of combustion. The low complexity of these systems, compared to steam, allows for more efficient and simple operation on a small scale in remote locations. Large scale hybrid coal and gas turbine programs are also presently being developed by United Technologies and Foster Wheeler under the USDOE Combustion 2000 program. These systems, which use pulverised coal and natural gas in an externally fired cascaded humid-air turbine, expect efficiencies of up to 55%. 5-5

Potential for CO2-Sequestration and Enhanced CoalBed Methane

Production in The Netherlands

Harry Schreurs, NOVEM, THE NETHERLANDS

According to Kyoto Protocol and agreement inside the European Union, the emission of carbon dioxide in The Netherlands has to be reduced be 6% in the year 2008 (related to1990). Disposal of carbon dioxide is one of the ‘back seat’ options to reach this goal. In co-operation between the Department of Economic Affairs and the Department of Housing, Spatial Planning and Environment in the Netherlands assignment was given to Novem to conduct a feasibility study and research. Goal was to research possibilities for storage of carbon dioxide in deep coal layers and parallel production of coal bed methane from these layers. The methane should be made profitable in an energy conversion system, based on (today available) best technology. The paper gives an overview of this study and will deal with the follow-up activities.

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The study investigated the technical and economic feasibility of using CO2 for the enhanced production of coalbed methane (ECBM) in the Netherlands. The work included an investigation of the potential CBM reserves in the Dutch underground and the related CO2 storage potential in deep coal layers. The latter was also supported by laboratory experiments on the adsorption capacity of coal. Furthermore, an economic evaluation of ECBM recovery was made by analysing the cost of capturing CO2 from major stationary sources and transport it, modelling the production of ECBM with reservoir simulations and system analyses to investigate the costs (and the sensitivities) of gas production. Furthermore, the costs of on-site hydrogen and power production (including on-site removal and injection) were evaluated. CO2 sources in the Netherlands have been inventoried. Annually 3.4 Mtonne CO2 can be captured from chemical installations and transported to sequestration locations at 15 Euro/tonne. Another 55 Mtonne from power generating facilities can be delivered at 40 to 80 Euro/tonne. The technical potential of CBM in the Dutch underground is significant: a maximum reserve of 60 EJ is stored in coal layers up to a depth of 2000 m..This figure should be compared to the current annual Dutch energy consumption (about 3 EJ) or the known reserves of natural gas in the Netherlands (about 70 EJ in 1994). The resources are concentrated in four main areas, mainly in the southern and eastern part of the Netherlands. The CO2 storage potential could be about 8 Gtonne. This potential should be compared to the annual CO2 emission of the Netherlands: about 180 Mtonne. Pure theoretically it means that the total CO2 emission of the Netherlands could be stored in coal layers for over 40 years and that CBM could meet the total national energy demand of the Netherlands for 20 years. However there are still a lot of uncertainties. With conservative assumptions the 'proven' CBM reserves could be limited to 0.3 EJ, with 'possible' reserves up to about 3.9 EJ. The accompanying CO2 that can be sequestrated than lies between 54 Mtonne and 0.6 Gtonne. Although these figures are far more modest, they still are significant. Without any subsidies or carbon taxes, the cost levels for ECBM recovery ranges from 3.5 to 6.5 Euro/GJ methane produced. These levels come close to the projected natural gas prices in Europe in a time frame of 10 to 20 years (2.5 to 3.2 Euro/GJ). Inclusion of a carbon tax (or bonus) of 25 Euro/tonne CO2

sequestrated, lowers the price of ECBM to a competitive 1.5 to 4 Euro/GJ. Including this bonus on-site power generation (and direct injection of the CO2 in the coalfield) as well as hydrogen production comes to cost levels comparable with standard (fossil fuels) situation. However a number of important (geo) technical and geological factors play a key role in wether these cost levels can be achieved or not. Dominating factors are costs per wellhead (drilling and methods of drilling) and the actual accessibility and productivity of CBM gas in the coal layers.

SESSION 6

METALLURGICAL INDUSTRIAL PRACTICE

6-1

New Approach for Coke Strength Estimation using Homogenization Method

Soejima Munetaka, Asakuma Yusuke, Yamamoto Tsuyoshi, Aoki Hideyuki, Miura Takatoshi, Tohoku University, Kato Kenji, Nippon Steel Corporation,

JAPAN

Coke strength that is one of the most important coke qualities is analyzed by using homogenization method. Coke strength is known to be governed by substrate strength, porosity, pore size and micro cracks of the coke. These kinds of microstructure of coke is formed by such as raw coal chemical characteristics, bulk apparent density, coal particle diameter distribution and heating condition. Researchers have carried out so many studies for optimization of coal carbonization such as blending coal. However it is very difficult to understand the coke characteristics because coking mechanism in oven chamber is unknown especially physical and chemical interactions between blended coals are complicated phenomenon. Our purpose of this study is to understand which microstructure forms stronger coke. It is possible to simulate the macroscopic behavior from the microscopic mechanical characteristics by using homogenization methods. Moreover, the inverse simulation allows the computation of the microscopic stress distribution from the macroscopic stress fields. Since the finite element model obtained by this method is the direct

interpretation of the scanned image presented micrographs of real coke, the homogenization analyses can include the effects of the original geometric configuration that depend on raw coal. Although homogenization method requires the microscopic mechanical properties, it has been difficult to measure the substrate strength of coke that has many small pores. Nano-indentation method enables us to determine the mechanical properties in the microscopic region by coupling the analytical results with experimental measurements. The substrates of coke are measured for each coke texture that originated in the raw coal components and the relationship between the substrate strength of coke and the coke texture is clarified. The mean elastic modulus of inerts, flow texture, mosaic texture and isotropic texture is 19.2 GPa, 18.1 GPa, 16.7 GPa and 18.0 GPa respectively. Coke strength is predicted by using the microscopic properties measured. The results show that the porosity and the substrate strength can be related to effective elastic modulus that is a standard of the global coke's strength. Pore positions and the pore diameter distribution especially influence the local stress concentration. Those two scale effects determine the fracture behavior of coke. Such results will be used to optimize the process for making high quality coke. 6-2

Utilization of Coal in the Steel Industry

Vaclav Roubicek, Ivo Janík, Jirí Bilík, Jan Kret, VSB - Technical University of

Ostrava, CZECH REPUBLIC

The lecture deals with a detailed analysis of the principal aspects of a wider utilisation of coal in metallurgy. The lecture introduction analyses major problems of an effort to innovate the traditional process of chamber coking, and the process further development confines. A detailed analysis of possibilities of substituting the blast furnace coke with blasting pulverised coal into the tuyères, injecting gas synthesised both from lignite and coal, or injecting lignite tar, all relate to the lecture introduction. The analysis has been based on calculation variants for injection effects, as regards especially developed mathematical models, and the related comparison of the results with the outputs of operational experiments performed at the Czech blast furnaces. A special attention has been paid to the assessment of possible utilisation of gases from the mine degassing the Ostrava-Karvina and Upper Silesia coal districts. The existence of these gases represents a major environmental hazard. The lecture reports on the project of employing such gas for both the direct injection into the blast furnace and especially its utilisation for preliminary reduction, or even a complete reduction to metal of iron ores, pellets, and sinter inside the shaft reactor. Such pre-processing products represent a partially pre-reduced blast furnace stock and, in instances of high rates of metal reduction, a metal sponge for a direct steel processing. The principal idea of the direct utilisation of coal in metallurgy is represented by the alternative preparation of steel charge, including the substitution of a considerable amount of scrap and raw iron with a quality iron sponge and raw iron produced outside a blast furnace by employing coals unsuitable for coking. Economically satisfactory alternatives for ratios of raw iron, DRI/HBI, and scrap in the steel charge have been calculated. A special attention has been paid to the variant of progressive making up for the disappearing blast furnace, coke, and sinter productions with MIDREX-COREX processes, which are exclusively based on the direct utilisation of appropriate coal. The lecture closing remarks contrast technological and economical variants for particular coal and coal gaseous derivatives utilisation in metallurgy. 6-3

The Role of Coal in Direct Reduction of Iron Oxides

Gui-su Liu, John A. Lucas, CRC for Coal in Sustainable Development, Vladimir

Strezov, Louis Wibberley, BHP Newcastle Laboratory, AUSTRALIA

New ironmaking technologies often use pellets, which are made of coal and iron ore fines, to make direct reduced iron (DRI). The reactions occurring during the reduction of coal-ore pellets are much complicated, and the coal plays an important role in the whole reduction process. Nevertheless the understandings of the fundamental reactions occurring in coal-ore mixtures have not been paid much attention until recent years the rapid development of DRI technologies. In this paper, thermal properties of single coal, iron ore and their mixtures have been measured using an advanced thermal property technique. The samples were heated up to 1000°C at a typical rate of 10°C/min under an argon atmosphere. Specific heats against temperature for samples were obtained, from

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which fundamental reactions can be understood. It has shown that the iron ore undergoes several reactions prior to its reduction with reducing gases. The iron ore reduction occurs progressively with an increase in temperature, with the onset of reduction of Fe2O3 at a temperature as low as 580°C, followed by the reduction of Fe3O4 and FeO at higher temperatures. Coal devolatilisation has been found to play an important role in iron ore reduction of coal-ore mixture at temperatures below 920°C. No significant difference has been observed between thermal coal and coking coal when mixing with iron ore. Similar endothermic or exothermic peaks exhibited at different heating rates. The apparent thermal conductivity of coal and iron ore mixtures were found to be within a range of 0.4-1.0 W/m.K over the whole temperature range investigated. 6-4

Demonstration of HIsmelt® Process in DOE’s Clean Coal Technology

Program

Douglas M. Jewell, Reginald Wintrel, CPICOR Management Co., USA, Adrian Muir, HIsmelt Corporation Pty Ltd. Kwinana, AUSTRALIA

The U.S.Department of Energy’s Clean Coal Technology Demonstration Program (CCT) is a model of government and industry cooperation. The CCT Program responds to DOE’s mission to foster a secure and reliable energy system that is environmentally and economically sustainable. The CCT Program represents an investment of over $5.2 billion, with industry and state governments providing an unprecedented 66% of the funding. The CCT Program is providing a portfolio of technologies that will assure that both U.S. and global recoverable coal reserves can continue to supply the world’s energy needs. Approximately thirty-eight projects have either been completed or are completing design and permitting activities. Although the majority of these projects focus on power generation, a significant number address coal processing and / or industrial uses of coal. One project actually combines more than one goal: this is the Clean Power from Integrated Coal / Ore Reduction (CPICOR™). The CPICOR™ project will demonstrate the integration of direct iron making with the coproduction of electricity using low-grade ores and coals. The project will use the HIsmelt® direct iron making process, which was developed and pilot-tested at Kwinana (Perth), Western Australia. The HIsmelt® process is based on producing hot metal and slag from iron ore fines and non-coking coals, e.g.,in the absence of coke and iron pellets or sinter. The heart of the process is producing sufficient heat and maintaining high heat transfer efficiency in the post-combustion zone above the combustion zone to reduce and smelt iron oxides. The excess heat is recovered for power production. The CPICOR™ project is being designed to produce 3,300 tons/day of liquid iron and ~160 MW of electricity for use either by the host steel mill or for export to the grid. The HIsmelt® process has been developed for Australian coals and ores; however, the pilot plant has shown excellent response / applicability to U.S. coals. The Demonstration project will use >2700 tons / day of local non-coking coal. The project will also integrate an air separation unit to provide up to 1200 tons / day of low purity oxygen. The project will be constructed at the Geneva Steel Works in Provo, Utah; the high quality virgin liquid metal will be directly fed into a BOF to produce a variety of steel products. The project is designed to operate exclusively on indigenous coals and iron ores from the Utah region. The process will also operate beneficially on various levels of iron reverts and waste cokes commonly found at most integrated steel operations. DOE believes that the HIsmelt® process in this CPICOR™ demonstration may lead to direct replacement for existing blast furnaces and coke making facilities with additional potential to produce steam for both facility process use and power production. Cogeneration of electricity is a powerful environmental and economic incentive for adoption by the world coal and steel industries. 6-5

Review of Environmental and Operating Credentials of New and Emerging

Coke-Making Technologies

G.D. Rigby, L.J. Wibberley, M.R. Mahoney, BHP Minerals Technology, N.J. Bristow, S.J. McGuire, BHP Coal, AUSTRALIA

Coke strength that is one of the most important coke qualities is analyzed by using homogenization method. Coke strength is known to be governed by substrate strength, porosity, pore size and micro cracks of the coke. These kinds of microstructure of coke is formed by such as raw coal chemical characteristics, bulk apparent density, coal particle diameter distribution and heating condition. Researchers have carried out so many studies for optimization of coal carbonization such as blending coal. However it is very difficult to understand the coke characteristics because coking mechanism in oven chamber is unknown especially physical and chemical interactions between blended coals are complicated phenomenon. Our purpose of this study is to understand which

microstructure forms stronger coke. It is possible to simulate the macroscopic behavior from the microscopic mechanical characteristics by using homogenization methods. Moreover, the inverse simulation allows the computation of the microscopic stress distribution from the macroscopic stress fields. Since the finite element model obtained by this method is the direct interpretation of the scanned image presented micrographs of real coke, the homogenization analyses can include the effects of the original geometric configuration that depend on raw coal. Although homogenization method requires the microscopic mechanical properties, it has been difficult to measure the substrate strength of coke that has many small pores. Nano-indentation method enables us to determine the mechanical properties in the microscopic region by coupling the analytical results with experimental measurements. The substrates of coke are measured for each coke texture that originated in the raw coal components and the relationship between the substrate strength of coke and the coke texture is clarified. The mean elastic modulus of inerts, flow texture, mosaic texture and isotropic texture is 19.2 GPa, 18.1 GPa, 16.7 GPa and 18.0 GPa respectively. Coke strength is predicted by using the microscopic properties measured. The results show that the porosity and the substrate strength can be related to effective elastic modulus that is a standard of the global coke's strength. Pore positions and the pore diameter distribution especially influence the local stress concentration. Those two scale effects determine the fracture behavior of coke. Such results will be used to optimize the process for making high quality coke.

SESSION 7

COAL GEOSCIENCES & RESOURCES-II

7-1 Quantitative Mineralogical Analysis Of Coal And Associated Materials By

X-Ray Diffractometry

Colin R. Ward, University of New South Wales, AUSTRALIA

The mineral matter in coal encompasses any dissolved ions in the pore waters and inorganic elements associated with the organic matter (a combination that may be collectively referred to as non-mineral inorganics), together with a sometimes quite significant proportion of crystalline mineral particles. Many of the problems associated with coal preparation and use are related either directly or indirectly to the nature and relative abundance of particular mineral matter components. Such problems include sulphur and phosphorus content, materials handling characteristics (stickiness; clay dispersion), abrasion, slagging and fouling, as well as the release of potentially toxic elements to the environment in leachates from mines, stockpiles and refuse emplacements. Mineralogical analysis is concerned with determining the nature and relative proportions of the different minerals in a rock, coal or similar material. It differs from chemical analysis, which involves determining the relative proportions of chemical elements, and from petrographic analysis where the relative proportions of constituents with different appearance, such as the different coal macerals, are determined by microscopic study. Although many of the non-mineral inorganics in coal may be evaluated by chemical analysis methods, quantitative assessment of the relative abundance of the different minerals in coal is a much more difficult task. The most definitive basis for mineralogical analysis is X-ray diffraction (XRD), which distinguishes minerals from each other on the basis of their atomic or crystal structure. This is particularly important for components such as clay minerals, which are difficult to identify by any other means. Although highly regarded as a tool for mineral identification, XRD has traditionally been used only in a qualitative or semi-quantitative way, due among other factors to the inherent variability of crystal structure in some mineral components. However, XRD has benefited from recent developments in computer processing that have allowed it to be used for more precise quantitative determination of mineral percentages. An example is the SIROQUANT technique for quantitative XRD evaluation, developed in Australia by CSIRO and based on Rietveld methods of diffraction pattern analysis. The SIROQUANT technique involves interactive adjustment of the diffraction patterns of individual minerals to allow for crystallographic variations, and combines the adjusted patterns to match the observed XRD profile of the sample under analysis and evaluate the percentages of the different minerals present. The present paper discusses the use of SIROQUANT for determining the mineral percentages in a range of coals and associated rocks from Australia and the USA, including coals from the Sydney, Gloucester, Gunnedah and San Juan Basins, and the Argonne Premium Coals reference set. Supplementary data have been obtained in most cases from detailed evaluation of the clay minerals,

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using special oriented-aggregate XRD techniques. The materials investigated include raw coal samples, as well as low-temperature ashes isolated from the coals by radio frequency activated oxygen-plasma techniques. Some higher-temperature ashes, prepared by heating the coals in air to around 400°C, have also been analysed. The chemical composition calculated from the mineral percentages determined by SIROQUANT is typically very close to the actual chemical composition of the same materials determined by direct chemical analysis, confirming that the quantitative XRD results are consistent with other indicators of mineral matter constitution. Clay mineral proportions indicated by SIROQUANT from powder diffraction data are also similar to the relative proportions estimated within the clay fraction from separate oriented-aggregate XRD analysis. The availability of a more quantitative basis for mineralogical analysis provides a range of opportunities to relate mineral matter characteristics to other coal properties. As an example, the abundance of key trace elements in coal has been related, for an Australian coal basin, to the abundance of particular mineral components. Quantitative analysis also provides an opportunity to establish links between the mineral assemblages in coals and the mineralogy of slags and other furnace deposits, and to evaluate the behaviour of mineral matter in a range of coal utilisation processes. 7-2

Quantitative X-Ray Diffraction Analysis of Mineral Matter In Raw Coals

David French, John Taylor, Les Dale, Chris Matulis, CSIRO Division of Energy

Technology, AUSTRALIA

Coal mineral matter plays an important role in all aspects of coal science from mine geology, resource development and preparation through to utilisation. It is also responsible for many of the deleterious properties of coal such as stickiness in coal preparation, formation of slagging and fouling deposits in combustion, and is the principal host for many of the environmentally significant trace elements. X-ray diffraction has been an essential tool for the characterization of coal mineral matter as most minerals have a unique diffraction signature which can be used both for identification and quantification of mineral abundances. With the development of SIROQUANT, a quantitative X-ray diffraction computer program based upon the Reitveld method, it is possible to quantitatively determine coal mineral matter abundances in raw coal samples. A major obstacle to the determination of mineral matter in raw coal has been the difficulty of quantifying the organic fraction which gives rise to a poorly defined X-ray diffraction hump. A structure model has been developed in SIROQUANT to simulate the organic fraction which allows direct determination of the total percentage of organic matter in the coal, and hence the total mineral content as a percentage of the coal sample. A good correlation has been observed, using this structure model, between the total mineral matter percentage determined by raw coal XRD and the mineral matter percentage determined (as a fraction of the coal) by radio-frequency ashing techniques. Detection limits are also comparable and not greatly affected by dilution with organic material due to the low mass absorption characteristics of the organic fraction. The technique has been applied to the determination of minerals in the various streams of a coal preparation plant thereby allowing the partitioning of the mineral phases in the coal preparation process to be determined. The implications of these results for coal preparation will be discussed. 7-3

A New Approach to the Acid-Base Account by Using Programmed-

Temperature Oxidation and Evolved Gas Analysis

Douglas G. Kern, Robert B. LaCount, Waynesburg College, Richard W. Hammack, U.S. DOE/NETL, USA

The acid-base account is the most commonly used method for assessing post-mining water quality. Yet the conventional acid-base account has recognized analytical deficiencies including the use of total sulfur to calculate acid potential (AP) when pyritic sulfur is the only significant contributor, and the use of a subjective fizz test in the determination of neutralization potential (NP). Moreover, the acid-base account makes no allowance for reaction kinetics in either the calculation of the AP or NP. This paper describes a new method for coal overburden analysis that corrects the analytical deficiencies of the acid-base account. Thermal methodology has been developed that will selectively decompose alkaline earth and transition metal carbonates to provide well-resolved carbon dioxide evolutions for each species. Sulfur forms present in the sample mixture

are selectively oxidized to sulfur dioxide and determined from the same analysis. The thermal conditions were developed using a Controlled-Atmosphere, Programmed-Temperature Oxidation (CAPTO) system where temperature ramp, gas flow, gas composition, and pressure are all under computer control and evolved gases are analyzed using Fourier Transform Infrared (FTIR). The carbon dioxide/sulfur dioxide evolution temperatures have been related to the carbon/sulfur forms in the sample producing the evolved gases. Thermal treatment conditions that produce well-resolved carbon dioxide/sulfur dioxide evolutions were established for a series of individual alkaline earth and transition metal carbonates, synthetic mixtures of these carbonates with pyrite, and finally numerous overburden samples. This thermal procedure provides an alternative method that may be of use in determining NP in mine overburden samples which contain both alkaline earth and transition metal carbonates. 7-4

Petrographic Characters of Selected Gondwana Coals of India

Krishna K. Sappal, Curtin University of Technology, AUSTRALIA

The Permian coals of India are referred to as Gondwana Coals, named after indigenous "Gond " tribe of eastern India. These coals are signi cant source of energy for rapidly growing economy of India. The coals rep resent 99% of thermal and coking coal resources of India, with an estimate of 21 billion tonnes resource for the population of approximately one billion people. The Gondwana coals were deposited under a set of geological, biological and chemical environments which provided unique petrograhpic characters, somewhat similar to the Permian coals of Australia. Most of the Permian coal basins of India are elongate, half graben structures located in Damodar, Son-Mahanadi, Pench Kanahan and the Pranhita-Godavari valleys of east, east central and south central parts of India. The coals have subdued lustre due to the presence of fine laminations and associations of finely dispersed mineral matter within dull and bright lithotypes. The vitrinite and inertinite group of macerals are dominant contents with minor macerals of exinite group. The trace elements in the coal of environmental concern are categorised as major, moderate, minor and the radiocatives like thorium and uranium. The petrographic characters and sedimentological studies of inter seam sequences suggest that the Gondwana coals were mostly deposited in fluviatile environments. 7-5

Paleofluid Flow Induced Cleat Mineralisation In The Bowen Basin,

Queensland, Australia: Implications For Coalbed Methane Exploration In Foreland Basins

Basim Faraj, Faraj Consultants Pty Ltd, AUSTRALIA

Cleat mineralisation and orientation studies in the Bowen Basin reveal the critical role played by regional paleofluid flow during orogenic phases on the development of coal cleats and mineralisation. Cleat mineralisation is analogous to cement in conventional gas reservoirs and reduces the permeability and porosity of the coal seams. The Bowen Basin was affected by two major mineralisation episodes: 1) A clay mineralisation episode with systematic variation in clay mineral assemblages across the basin from east to west as follows: Pure illite; illite-chlorite; illite-rich illite/smectite, chlorite and kaolinite; and finally pure kaolinite. These strongly depleted 18O assemblages preferentially mineralised cleats and other fracture systems that parallel the major thrusting and compressive stress direction during the Triassic's orogenic phase. This system was a result of a large scale gravity-driven highly 18O depleted meteoric water flow under high heat flow conditions, as the mechanism by which this mineralisation event took place. The water flow was maintained by a combination of topographic highs at the eastern edge of the basin and the thrusting advancement of the Triassic's Hunter-Bowen Orogeny. The mineralising meteoric water penetrated down to 4km into cleats of the Rangal Coal Measures. The underlying thick, tuffaceous and clay-rich Fort Cooper Coal Measures acted as a permeability barrier and prevented deeper circulation of this water into the well-cleated Moranbah coal seams. 2) The second mineralisation episode occurred during cycle of subsidence that commenced in the Early Jurassic. During this cycle, widespread calcite mineralisation took place. It is pervasive in butt cleats and nearly absent in face cleats, attributed to permeability anisotropy

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caused by a change in the orientation of principal stresses at this time as a result of a milder compressive deformation in the middle Cretaceous. The overall mineralisation pattern was also mostly confined to the Rangal's, similar to the earlier episode. These findings should be incorporated in exploration strategies for methane gas in this area and in similar settings worldwide.

SESSION 8

GASIFICATION: MARKETS/PROJECTS-II

8-1

IGCC Fuel Flexibility and Co-Production Capabilities Provide Economic Opportunities for New Power Generation Needs

Robert M. Jones, GE Power Systems, USA

Integrated Gasification Combined Cycle (IGCC) system designs are meeting today’s generation needs with improved capabilities and plant efficiencies through a combination of technology advancements, co-production facilities, and cost effective power generation capacities developed from coal and other low valued opportunity fuels. Today there are over 6 GW of IGCC capacity under design, construction, or in operation and many more projects under development. The ability of this technology to accommodate wide variations in plant operations including fuel flexibility and variable power production requirements, demonstrates that considerable system optimization and process design integration is paramount to achieving project objectives. Several recent refinery based IGCC projects meet these challenges with exceptional performance and fuel flexibility. Similarly, coal gasification is again coming into focus driven in part by the continued system cost and performance improvements afforded by today’s contemporary designs, in addition to the recent rise in natural gas fuel pricing. GE currently has ten IGCC projects that have moved into the operational phase, with seven more plants becoming operational within the next three years. These seventeen plants include commercially available heavy duty gas turbines from the complete GE product line resulting in IGCC plants ranging in size from 40 MW up to 800 MW in net output capacity. GE gas turbines have in total accumulated more than 325,000 fired hours on synthesis fuel gas, of which 135,600 hours were fired on syngas derived from coal feedstocks. The design and operational experience gained from these facilities has played a key role in the continued advancement of IGCC systems. The technology has matured to the point where IGCC systems are commercially competitive with all other power generation options, and is the clear choice in a wide variety of new power generation plants seeking fuel diversification using coal and other low cost solid feedstock opportunity fuels. The co-production of chemicals and other utility products required by refineries is a key advantage afforded by IGCC technology. By fully utilizing the capabilities of modern combined cycles, IGCC systems are able to achieve exceptional levels of environmental performance, availability, and efficiency at competitive cost of electricity rates. With the production of conventional syngas fuel components, the opportunity exists to further separate carbon elements prior to combustion and sequester CO2 where necessary. Improvement in advanced gas turbine technologies allowing for increased power densities, improved cycle efficiencies, and lower installed costs, will continue to permit IGCC systems to provide increased benefits and capabilities to refineries and other independent power generators for the foreseeable future. 8-2 Status of the EAGLE Project: Coal Gas Production Technology Acceptable

for Fuel Cells

Hideo Maruyama, Clean Coal Technology Center, Manabu Kubota, Electric Power Development Co.,LTD., JAPAN

The purpose of the EAGLE (coal Energy Application for Gas, Liquid and Electricity) project is to develop the technology to produce coal gas for fuel cells. The EAGLE has an oxygen blown, entrained flow type gasifier. The gasifier has a single chamber with a two-stage spiral flow. Oxygen is produced with an ASU (Air Separation Unit) and supplied to the gasifier. The produced coal gas is cooled in the gasifier and a syngas cooler. Impurities in the syngas are removed by water scrubbers, a COS converter and an MDEA (Methyl Die Ethanol Amine) absorber. Part of the syngas is further desulfurized by iron oxides for fuel cells.

The EAGLE project is subsidized by METI (the Ministry of Economy, Trade and Industry). Table 1 shows the development schedule. In 1995, an IGFC (Integrated coal Gasification Fuel Cell combined cycle) feasibility study and element tests were conducted. Following a basic design and a detailed design, civil work was started at Wakamatsu Operations & General Management Office in 1998. The pilot plant was built from 1998 and completed at the end of June 2001. At present, operation tests are in progress from July 2001. This paper outlines the construction status of the pilot plant. 8-3

Biomass Gasification Co-Firing Project in Kentucky

Francis Lau, Joseph Rabovitser, Bruce Bryan, David Stopek, Gas Technology

Institute, USA

The Gas Technology Institute (GTI) and Calla Energy Partners LLC has teamed up to develop a biomass gasification co-firing project to produce 15 MWe of electricity from biomass and other opportunity fuels in the Eastern Kentucky region. The electricity and steam generated will be consumed by a nearby industrial park. Excess electricity will be sold to the grid. The heart of the project is the demonstration of GTI’s RENUGAS® biomass gasification technology and a low NOx burner developed for this combustion application. Under this program, GTI will provide a gasification plant based on the RENUGAS® gasification technology. The unit will be designed to process 400 tons per day of biomass consisting of sawdust and other opportunity fuels into low calorific value fuel gas. The project will evaluate designs for co-firing this gas with natural gas or coal in Calla Energy’s boilers located at the industrial park. GTI will utilize its low- emission gas combustion systems to reduce NOx emissions from boiler. Steam from the boiler will drive a conventional steam turbine for electric power generation. The biomass contribution is equivalent to producing 15 MWe of electric power. Waste heat from the plant will be utilized in the nearby industrial park. An existing coal fines recovery operation reclaiming coal from ponds at the site is the anchor tenant of the industrial park and will use steam extracted from the turbine for drying of coal fines. The plant, to be built in Estill County, Kentucky, will be the cornerstone of the Calla Energy industrial park. Calla Energy plans to offer low-cost, reliable electricity and steam at their 600-acre industrial park to attract a variety of tenants that will promote new jobs and stimulate economic growth in this area of Kentucky. Calla Energy will provide the host site and will be the owner of the energy plant The U.S. Department of Energy (DOE) has selected this project team to develop and commercially demonstrate biomass gasification as part of their biomass co-firing program. The successful demonstrate of this project will provide a sustainable and environmentally clean source of energy for power generation to the site and create new economic opportunities for rural America. 8-4

New Shell Coal Gasification Projects: Impact of Feed Composition and

Syngas Application on their Design

J.E.G. Ploeg, Shell Amsterdam, THE NETHERLANDS

The Demkolec IGCC plant, based on the Shell Coal Gasification Process and the Siemens V94.2 Gasturbine, was started in 1994. The gasification plant, designed for gasifying “International traded coal”, has in the mean time logged some 30,000 operating hours and has indeed gasified a large variety of coals; most as blends to arrive at the cheapest possible feedstock while staying within the design sulphur and ash concentrations. Biomass (sewage water treating sludge and chicken manure) has become part of this blend since late 2000. SCGP projects presently being developed are, in general, not based on “International traded coals” but on local available, poor quality (high ash and/or high sulphur content) coals or on petroleum coke. “Lessons learned” from the SCGP test units and from the Demkolec operations will be used to describe modifications in the design and operation of the SCGP units for these projects to cope with the different heating values and sulphur contents, but mainly with the large differences in ash content and ash quality. Why these designs can be different when evaluating the application of SCGP for syngas production, rather than IGCC, projects will become evident.

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8-5

Performance Improvements Made in Gasification Operation Through Optimization of Control

M. Walter, W. Hefner, BASF AG, GERMANY

At Ludwigshafen production site BASF is operating a synthesis gas plant according to Texaco POx-process. BASF is operating one quench gasifier (since 1965) and 4 waste-heat boiler type gasifiers (since 1974). Feed stocks are heavy resid and visbreaker tar. BASF synthesis gas plant is the front end of a integrated chemical production site. Due to the fact that it is serving 90 downstream plants gas production has to be very reliable. Latest improvement is the introduction of a DCS and a Triconex PLC incorporating newest Texaco standards. Mechanical optimization of key equipment and introduction of state of the art DCS and PLC have improved reliability remarkable. Automatic start-up and shut-down of the gasifiers with minimum operator assistance is now possible. Key feature to improve gasifier run time is an automatic load control device. However, high reliability of these modern systems is only assured if sensors and actors in the system are working well. The paper presents the associated challenges in improving mechanical and electronic equippment. Furthermore, the paper describes numerous difficulties arising when switching from man-made safety (old pneumatic control systems) to computer controlled safety. Topics are simple technological problems and questions borne in introducing latest HAZOP standards, as well.

SESSION 9

PULVERIZED COAL COMBUSTION-II

9-1

New On-Line Acoustic Techniques for Mass Flow and Particle Size Determination of Pulverised Coal

Michael Millen, Peter Coghill, Brian Sowerby, CSIRO Minerals, AUSTRALIA

On-line analysis systems for the minerals and energy industries are replacing manual sampling and laboratory analysis by providing continuous, rapid and accurate process data in real time. These systems are widely used in industry primarily for the on-line bulk analysis of composition (elemental, mineralogy, moisture, ash, etc), multiphase flow rates, particle size and gas composition. A range of techniques including nuclear, microwave, laser and techniques are commonly used in on-line analysis systems. The topic of the present paper covers the development by CSIRO Minerals of acoustic techniques for the measurement of the mass flow rate and particle size of pulverised fuel in boiler feed pipes in coal-fired electricity generating stations. A commercial prototype multi-pipe pulverised fuel (PF) mass flow measurement system has been developed and installed at two black coal-fired power stations in NSW, Australia. A new system is also under development through the Cooperative Research Centre1 (CRC) for Clean Power from Lignite for deployment in lignite fired power stations in Victoria, Australia. The main incentive for developing such systems is to detect non-uniform distribution of PF between boiler feed pipes. Using this information to balance the burners under a range of boiler conditions would lead to improved combustion efficiency, improved control of NOx emissions, reduced boiler tube erosion and reduced fouling and slagging. The mass flow measurement system utilises measurements of the attenuation and velocity of pulsed beams of ultrasound transmitted across the boiler pipes to determine the PF mass flow in each pipe. A new technique is under development for the measurement of particle size of pneumatically conveyed coal and other powders. The essence of the technique is to monitor the acoustic waves produced by collisions of the particles with a specially designed sensor. An impact size monitor (ISM) suitable for laboratory and plant tests has been developed. 9-2

A Thermodynamic Model for the Evaluation of the Akali Removal

Potential of Sorbents for the Pressurized Pulverized Coal Combustion (PPCC)

Bernd Meyer, Tim Bause, Freiberg University of Mining and Technology,

GERMANY

The sorptive removal of alkali species from hot flue gas in order to meet the specifications of gas turbine producers has been observed in the past years.

Almost all investigations were carried out with regard to processes of integrated coal gasification. In spite of the intensive research on alkali removal, it still remains a problem in the PPCC process. This is due to the extreme process conditions of this process. The alkali removal has to be realized at temperatures between 1350 and 1400°C. Known investigations deal with temperatures below 1200°C, since the alkali removal of the observed processes takes place below 1200°C. Performed thermodynamic calculations are also limited to 1200°C due to a lack of thermodynamic data at higher temperatures. The present work introduces a thermodynamic model for the evaluation of the alkali removal potential of solid sorbents, that considers the formation of melts and non-ideal mixtures and is therefore applicable to temperatures above 1200°C. 9-3

Application of the F*A*C*T Thermodynamic Computer Package to

Prediction of the Ash Fusion Temperatures

Evgueni Jak, CRC for Coal in Sustainable Development, AUSTRALIA

The focus of the paper is prediction of Ash Fusion Temperatures (AFTs). AFTs are widely used as a measure of coal ash fusibility and melting behaviour. Hence, AFTs of coals and coal blends is one of the parameters currently widely used by coal marketing companies and power generation utilities to assess coal quality. It is important to be able to predict AFTs to assist in coal blending, and to optimise and maximise the use of coal resources. Research on AFTs also provides a better understanding of the meaning of this test, and correlations between the AFT values and actual behaviour of the coal ash in industrial processes. There have been a number of studies on the prediction of AFTs from the coal ash compositions including empirical and statistical correlations derived using regression analysis [1-10], neural networks [11], and thermodynamic considerations [12-13]. Huggins et al [14-15] discussed the deficiencies of the empirical and statistical approaches and demonstrated that AFTs could be correlated with phase equilibria. Unfortunately at that time only ternary liquidus diagrams were available and the results were only qualitative. In the present paper AFTs are predicted using the liquidus temperatures computed by the thermodynamic computer package F*A*C*T. New thermodynamic database for the SiO2 -Al2O3-CaO-FeO-Fe2O3 system developed by the authors is used in conjunction with the F*A*C*T for these purposes. The strength of this approach is that it is based on phase equilibrium science rather than simple composition relationships. The relative stabilities of the liquid and solid phases therefore are taken into account. The research described in the present paper examines the relationship between measured AFTs and F*A*C*T liquidus calculations for a selected set of coals. Quenching experiments have been undertaken to investigate mineral interactions and phase transformations in the real AFT ash cones. Microstructural analysis of the quenched cone sections followed by the Electron Probe X-ray Microanalysis (EPMA) of the liquid and crystalline phases were used to examine the formation of the solid phases in these coal ashes. The experimental observations and measurements were compared with the F*A*C*T equilibrium predictions. Detailed description of the experimental results will be given in the paper. This way a model for the AFTs predictions based on the F*A*C*T calculations has been developed, accuracy of the AFT predictions has been rigorously examined and compared to the inherent variability of the AFT test measured as part of the research program. The AFT model has been applied for predictions of the optimum coal blending strategies. AFTs of the coal blends prepared based on the recommendations were measured and compared to predictions. Good agreement between predictions and measurements was observed. The AFT model is currently being used in coal mine planning. The work outlined in the paper has been undertaken as part of the Collaborative Research Centre for Black Coal Utilisation with assistance from the BHP Coal Ltd. 9-4

Advanced Indices for Ash Deposition and Slag Flow During Coal

Combustion

Thomas Erickson, Christopher J. Zygarlicke, Donald P. McCollor, Jason D. Laumb, Steven A. Benson, University of North Dakota, USA

A series of advanced indices have been developed and validated that rank coals according to their propensity to cause ash deposition and have good slag flow tendencies. These indices are based on more sophisticated analytical techniques

12

for identifying and quantifying coal inorganic composition, greatly improving their reliability compared to conventional indices. The ash deposition indices package developed at the Energy & Environmental Research Center (EERC) is called PCQUEST, an acronym for Pulverized Coal Quality Effects Screening Tool. PCQUEST is a personal computer-driven software package that calculates indices for low- and high-temperature ash fouling for both cyclone and pulverized coal-fired boilers, cyclone combustor slag-tapping propensity, stack opacity, ash erosion, grindability, and sootblowing effectiveness. The indices are derived using coal inorganic content input from computer- controlled scanning electron microscopy, bulk coal ash elemental composition, proximate–ultimate analysis, and chemical fractionation analysis. A higher number represents greater fouling or slagging. Assumptions used in weighing the relationship among the key coal inorganic constituents are based on years of studying coal inorganic content and ash deposition mechanisms in a variety of coal combustion systems. The indices provide much more accurate diagnostic information for predicting the ash deposition behavior of coal than conventional indices, which are based on simplistic ASTM (American Society for Testing and Materials) coal analysis data. Recently, PCQUEST has been tested on 30 additional coals, including coals from the United States, Canada, Europe, and South America. In addition, better predictions for erosion wear rate and slag flow behavior have been included in PCQUEST. 9-5

Predicting Ash Effects in Combustion Based on The CCSEM Analysis of Minerals in Pulverised Coal

Sushil K. Gupta, Raj P Gupta, Terry F Wall, Karen Katrinak, Steve Benson, T.

Yamashita, CRC for Coal in Sustainable Development, AUSTRALIA

The detailed information of the inorganic constituents in coal is now frequently obtained by using the Computer Controlled Scanning Electron Microscopy (CCSEM) technique. The technique provides detailed information of the heterogeneity of the inorganic matter in coal in terms of mineral type, their size distribution and more importantly their association with the coal matrix. The paper highlights the significance of the excluded and included mineral information of coal in predicting the ash behaviour in various energy systems. The CCSEM measurements from various laboratories are compared to assess the confidence level in the measurements. The critical parameters influencing the accuracy of the measurements are identified and their effect on the validity of predictions is evaluated. The latest developments relating mineral transformation models for pf systems are reviewed including the effect of the char structure on coalescence of included minerals. The scientific basis of ash transportation, stickiness of ash, deposition rate and heat transfer mechanisms are also provided. Several case histories involving utilities from the Unites States, Australia and Japan employing a wide range of coals are presented to demonstrate the effectiveness of the CCSEM based model predictions in estimating the ash behaviour in pf combustion systems.

SESSION 10

LOW-RANK COAL UTILIZATION-II

10-1

Extraction of Low Rank Coals by Coal Derived Oils at 350 C for Producing Clean Fuels

Kouichi Miura, Kazuhiro Mae, Hiroyuki Shindo, Ryuichi Ashida, Takayuki Iha,

Kyoto University, JAPAN

We have recently presented a new coal solvent extraction method which enhances the extraction yield dramatically. The method extracts coal using a flowing stream of either tetralin or 1-methylnaphthalene under 10 MPa at 200 to 400 °C. The flowing solvent was used to minimize the secondary interaction between the extract and the macromolecular network of coal. When eight Argonne premium coals and an Austaralian brown coal (Morwell) were subjected to this extraction method, four bituminous coals were extracted with negligible decomposition below 350°C. The extract yield reached 65 to 80% for the bituminous coals at 350°C, and the extract was separated into about 25 to 40 % of soluble fraction at room temperature (soluble) and about 40% of solid precipitated at room temperature (deposit). It was found that the soluble and the deposit were almost free from mineral matters. Thus, this method was found to be effective to recover clean fuels from bituminous coals under rather mild conditions. However, this method was not effective for low rank coals.

To extend the extraction method to low rank coals and to make the method practically applicable, coal derived oils, carbol oil and creosote oil, were used instead of teetralin or 1-methylnaphthalene in this study. Fourteen kinds of coals were subjected to the extracttion by the coal derived oils at 350 °C. Almost all sub-bituminous coals and brown coals examined were surprisingly extracted by 80% in carbol oil at 350°C, and all extract was completely soluble in the oil even at room temperature. The quality of the extract was examined from the viewpoints of mineral matter content and sulfur content. It was found that the extract was almost free from mineral matters and that most of sulfur in coal removed through the extraction. Thus, it was clarified that the proposed method was also effective to produce a large amount of clean fuels from low rank coals under rather mild conditions. The mechanism of extraction and desulfurization were also examined in detail. 10-2

The Utilisation of Low Rank Coals

David J. Allardice, Allardice Consulting, Brian C Young, Envirosafe International, AUSTRALIA

This paper will address the major uses of low rank coals and the fuel specific technologies developed to cope with their quality constraints. While the emphasis will be on the vast Latrobe Valley brown coals from Victoria, Australia, reference will also be made to the growing importance of low rank coals in the international scene. Low rank coals are characterised by their high in-seam moisture content, typically 60-70% in the case of Latrobe Valley brown coals. Many other low rank coals have moisture contents in the 30-50% range, but this advantage is frequently offset by higher ash levels. The other common feature of low rank coals is their high reactivity in combustion, gasification, liquefaction and other processes. The combination of the high moisture content and high reactivity necessitates the use of these coals close to the mine, unless they can be upgraded to value-added products with better transport safety and economics. Their primary use is therefore power generation or to provide domestic and industrial fuels for local use, although a number of novel alternative fuel and non-fuel applications provide value-added potential for these coals. The paper will provide an overview of:

• the pattern of use of low rank coals; • current and advanced technologies for their use in power generation; • technologies for upgrading via drying, briquetting, carbonisation, gasification and liquefaction; and • other applications such as agricultural uses, carbon reductants for metallurgical use and activated carbons.

Reference will be made to inherent Greenhouse gas concerns associated with low rank coals and emerging technologies to ameliorate their impact. 10-3

Calcium Cations in Low-Rank Coals – Reexamination of Quantification Method and the Transformation of the Cations During Coal Processing

Akira Tomita, Hiroyuki Akiho, Erlan Rosyadi, Yohsuke Suzuki, Koichi

Matsuoka, Tohoku University, JAPAN

Metal cations in low rank coals play an important role during many coal utilization processes. It is, therefore, important to understand the mode of occurrence as well as their fate during coal processing. In order to determine the content of ion-exchanged metals, the selective leaching method has been proposed. Aqueous ammonium acetate solution has been thought to dissolve only these cations. We have checked the validity of this method by using a wide variety of coals, and found that the leaching with this solution resulted in the dissolution of not only ion-exchanged metals but also some calcium-containing minerals. Thus this method is unsuitable for quantifying the amount of metal cations. Instead of this method, we would like to propose a new method using CCSEM (computer controlled scanning electron microscope). CCSEM can quantify all kinds of mineral matter; both crystalline and amorphous ones. The content of ion-exchanged metals can be estimated by subtracting the sum of the mineral matter detected by CCSEM from the total metal content determined by other technique like XRF and ICP. Upon heat-treatment, these metal cations are transformed into various forms. As an example, we attempted to determine the fate of ion-exchanged calcium during low temperature ashing. It was revealed that, at least partly, calcium ions were converted to calcite and bassanite via the reaction with CO2 and SO2,

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respectively, which were evolved during ashing of coal. Chars prepared at higher temperatures were also analyzed with CCSEM, and the transformation of these metal cations was investigated. Since the chemical form of ash in resultant char is not the same as original mineral matter, it was necessary to establish a new diagnosis for classifying ash particles in CCSEM analysis. Finally, the behavior of these metal cations in gasification and liquefaction processes will be discussed. 10-4

Desulfurization by Using Ca Ion-Exchanged Brown Coal During

Gasification of Coal

Takayuki Takarada, Doki Yamaguchi, Gunma University, JAPAN

Since a low rank coal has a large amount of oxygen-containing functional groups, metal cations such as Ca, Mg, Na and K are originally exchanged with a part of functional groups and more amount of metals can be incorporated into coals by ion-exchanging with free functional groups. In this work, a new desulfurization technique using Ca ion-exchanged brown coal as a sorbent in a fluidized-bed gasifier is developed. When Ca-exchanged brown coal is pyrolyzed, the carboxylate salt dissociates, releasing carbon dioxide and leaving highly dispersed calcium compounds such as CaO and CaCO3. We already reported that CaO produced from Ca ion-exchanged coal was much more reactive toward H2S than that from limestone. In this study, we carried out the desulfurization experiments using Ca-exchanged brown coal char and investigated the gasification reactivity of Ca-exchanged char reacted with H2S. We found out that CaS involved in the Ca-exchanged char reacted with H2S have a large catalytic effect for the char gasification in steam or CO2. XRD analyses showed that Ca compound in brown coal char can keep retaining sulfur during steam and CO2 gasifications. It is concluded that ultra fine CaO particles in the char can play important roles not only in the desulfurization as a highly efficient sorbent but also in the gasification of coal char as a catalyst.

SESSION 11 GREENHOUSE GAS CONTROL & CO2 SEQUESTRATION-II

11-1

Assessment of Novel Technologies for CO2 Capture & Separation

Narendra Dave, Chris Fookes, Cherie Walters, CSIRO Energy Technology, AUSTRALIA

Subsequent to the 1997 Kyoto Protocol to the United Nations Framework Convention on Climate Change, developed nations have been looking at ways to minimise growth in greenhouse gas emissions. Large scale capture and separation of carbon dioxide at source and its permanent sequestration, while currently not attractive because of the costs and limitations of current technologies, nonetheless represents one of the few pathways by which very significant reductions from point sources might be achieved from the existing industrial infrastructure. As a result, a number of novel technological solutions have been put forward in the public domain for direct capture and separation of carbon dioxide from industrial flue gas streams. This paper summarises these novel options and compares with the currently available commercial technologies for CO2 capture and separation for their technical and cost advantages/limitations. The study shows that some of these novel technologies have potential to reduce the cost of CO2 capture and separation from oil and gas processing operations further from their current levels. Similarly, when applied to the power plant flue gas streams, they are effective to the point where recovered CO2 could be sold for enhanced oil recovery at US $10-15 per ton. However, for the purpose of substantial greenhouse mitigation, these technologies have a long way to go. 11-2

Evaluation of CaO-Added Gasification Process Incorporating CO2 Removal

Won-Gyo Jung, Hyung-Taek Kim, Ajou University, Su-Hyun Kim, Institute of

Advanced Engineering, Min-Cheol Kang, Korea Energy Management Corporation, KOREA

Worldwide coal reserves, whose amounts are about 7000 Gt are distributed most of the continents. To utilize the coal in the age of concerning global warming trend, CO2 from the coal utilization plant should be minimized. Gasification process can reduce most of pollutants such as SOx, NOx, particulates. However,

CO2 cannot be reduced in the one-step manner inside gasifier. In this paper, innovative gasification for the CO2 removal is simulated with ASPEN and various options are compared for the CO2 removal effectiveness. By adding CaO inside gasifier, CO2 from gasification process is adsorbed into CaO and the exothermic heat from carbonation can be utilized in the gasification process. As a result, CO2 can be completely removed from the product gas stream which can be utilized for high purity feedstock in the industry. Further, the temperature condition is reduced somewhat so that energy required for the gasification is considerably reduced. To systematically evaluated the process, every component will be modeled with ASPEN block and entire system will be integrated with various options. ASPEN simulation shows differences according to variable conditions related to temperature, pressure, and the amount of input materials. The best condition to remove CO2 will be determined by using ASPEN simulation. The CO2 reduction effectiveness is investigated with different combinations of the process and the economic consideration is also evaluated. 11-3 A Techno-Economic Comparison of Amine Scrubbing vs. O2/CO2 Recycle

Combustion for CO2 Capture from Coal Fired Power Plants

David J. Singh, Eric Croiset, Peter L. Douglas, University of Waterloo, Mark A. Douglas, CANMET Energy Technology Centre, Natural Resources, CANADA

The existing fleet of modern pulverized coal fired power plants represents an opportunity to achieve significant reductions in greenhouse gas (GHG) emissions in the coming years providing that efficient and economical CO2 capture technologies are available for retrofit. One option is to separate CO2 from the products of combustion using conventional approaches such as amine scrubbing. An emerging alternative, commonly known as O2/CO2 recycle combustion, involves burning the coal with oxygen in an atmosphere of recycled flue gas. Both approaches can be retrofitted to existing units, however they consume significant amounts of energy to capture, purify and compress the CO2 for sequestration. This paper presents a techno-economic comparison of the performance of the two approaches. The comparison was developed using a commercial process simulation package, HYSYS, and ICARUS a commercial economic evaluation system. The results to be presented will include the increased energy requirement of the CO2 mitigation system and the associated capital and operating costs for each case. The practicality of different integration issues is also examined with the goal of finding promising approaches to lower the overall cost of CO2 capture from existing coal fired power plants. 11-4

High Temperature CO2 Absorption using Lithium Orthosilicate

Sawako Yoshikawa, Masahiro Kato, Kenji Essaki, Kazuaki Nakagawa, Toshiba Corporation, Hideo Uemoto, Toshiba Ceramics Co., LTD., JAPAN

In order to reduce the emission of CO2, a number of large-scale CO2 separation techniques from fossil fuel combustion have been studied. Among all these techniques, the separation technique from the fuel gas before combustor is thought to be more advantageous than that from the flue gas after combustor. Since the fuel gas mostly has an elevated temperature at around 500oC, there was a difficulty of heat tolerance. There was no practical material which was applicable to the separation from fuel gas. We previously reported the possibilities of high temperature CO2 separation using lithium-containing oxides. These materials absorb CO2 at around 500oC and emit CO2 above 700oC. Further, all these reactions are reversible. Among these oxides, lithium orthosilicate (Li4SiO4) has the highest reactivity with CO2. This material absorbs CO2 at a rate 30-times faster than lithium zirconate (Li2ZrO3). In a gas flowing condition of 20% CO2 at 500oC, 1 g of lithium orthosilicate absorbs 60 mg of CO2 in a minute. In this work, the temperature and CO2 concentration dependences of the reaction between lithium orthosilicate and CO2 were evaluated using a thermogravimetric instrument. Our experimental data indicate that the absorption rate increases with the increase in temperature up to 600oC. On the other hand, the absorption rate has no clear dependence on CO2 concentration in the range 20% to 100%. On the basis of these findings, we discussed rate-determining steps of the reaction.

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11-5

CO2 Adsorption in Low-Rank Coals: Progress Toward Assessing the Nation-Wide Capacity to Store CO2 in the Subsurface

R. W. Stanton, R. C. Burruss, R.M. Flores, P.D. Warwick, U.S. Geological

Survey, USA

Subsurface environments for geologic storage of CO2 from combustion of fossil fuel include saline formations, depleted oil and gas reservoirs, and unmineable coalbeds. Of these environments, storage in petroleum reservoirs and coal beds offers a potential economic benefit of enhanced recovery of energy resources. Meaningful assessment of the volume and geographic distribution of storage sites requires quantitative estimates of geologic factors that control storage capacity. The factors that control the storage capacity of unmineable coalbeds are poorly understood. In preparation for a USGS assessment of CO2 storage capacity we have begun new measurements of CO2 and CH4 adsorption isotherms of low-rank coal samples from four basins. Initial results for 13 samples of low-rank coal beds from the Powder River Basin (9 subbituminous rank), Greater Green River Basin (1 subbituminous rank), Williston Basin (2 lignites) and the Gulf Coast Region (1 lignite) indicate that their adsorption capacity for CO2 is up to 10 times higher than it is for CH4. These values contrast with published measurements of the CO2 adsorption capacity of bituminous coals from the Fruitland Formation, San Juan basin, and the Gates Formation, British Columbia, that indicate about twice as much carbon dioxide as methane can be adsorbed on coals. Because CH4 adsorption isotherms are commonly measured on coals, CO2 adsorption capacity can be estimated if the correct relationship between the two gases is known. However, use of a factor to predict CO2 adsorption that is twice that of CH4 adsorption, which is common in the published literature, grossly underestimates the storage capacity of widely distributed, thick low rank coal beds. Complete petrographic and chemical characterization of these low-rank coal samples is in progress. Significant variations in adsorption measurements among samples are depicted depending on the reporting basis used. Properties were measured on an “as received” (moist) basis but can be converted to a dry basis, ash-free basis (moist), or dry ash free basis to emphasize the property having greatest effect on the adsorption isotherm. Initial results show that moisture content has a strong effect on CO2 adsorption. Our current sample base covers a limited range of coal rank and composition. Full characterization of the storage capacity of coalbeds in the US, will require additional samples that cover a broader range of coal compositions, ranks, and depositional environments. Even at this preliminary stage, we can use results from the recent USGS assessment of the Powder River Basin (Wyoming and Montana) to examine the impact of these new measurements on estimates of storage capacity. At depths greater than 500 feet, the Wyodak-Anderson coal zone alone contains 360 billion metric tons of coal. Using the new measurements of CO2 storage capacity, this coal zone could, theoretically, sequester about 290 trillion cubic feet (TCF) of CO2. This estimate contrasts sharply with an estimated capacity of 70 TCF using the published values for bituminous coals.

SESSION 12

METALLURGICAL UNDERLYING APPLIED SCIENCE

12-1

Consideration on Coal Plasticity in View of Maceral

Masakatsu Nomura, Koh Kidena, Mika Katsuyama, Satoru Murata, Osaka University, Tsukasa Chikada, Sumitomo Metal Industry Company Ltd., JAPAN

The different coal maceral has different chemical structure and plasticity. The maceral concentrates were analyzed to discuss coal plasticity. The correlation between structure and plastic property of two coals, Goonyella and Witbank coals, have been investigated. In this study, these two coals were used as sample coals, these being separated into six fractions by float-sink separation method. Two of six fractions of each coal were analyzed with 13C-NMR, ruthenium ion catalyzed oxidation, solvent swelling, and hydrogen transferability. These two kinds of maceral concentrates have apparently different Gieseler fluidity. The comparison between these two maceral concentrates was conducted for Goonyella (GNY) and Witbank (WIT) coal, respectively. The fraction with larger density contains 50% of inertinite and is low fluidity, while that with lower density corresponds vitrinite-rich fraction and is high fluidity. The former fraction is called as “A”, and the latter “B”. The results from 13C-NMR measurements showed “A” fraction higher aromaticity and fewer amounts of substituents than “B” fraction. Another

structural information was obtained by ruthenium ion catalyzed oxidation reaction, it being indicated that only WIT-B sample was richer in long alkyl groups attached to aromatic ring and long alkylene bridges connecting two aromatic clusters. This oxidation reaction can give information of only straight chains and bridges. Therefore, the difference between GNY-A and –B was considered to be branched alkyl and alkylene groups. The structural analyses implied that longer or branched alkyl and alkylene groups were preferable for the appearance of plasticity. Next, swelling behavior was observed for each sample. For both coals, “B” sample which has higher fluidity showed larger swelling ratio than “A” sample. As one of the mechanistic consideration on coal plasticity, low-molecular-weight component acts as a lubricant toward skeletal component. The coal sample with large swelling ratio can accept molecule. The results were well understood from this viewpoint. The amount of transferable hydrogen in the samples was checked by the reaction with anthracene at 420oC for 5 min. The previous study indicated that the amount of transferable hydrogen was well correlated with Gieseler fluidity. The “B” sample had larger amount of transferable hydrogen, this also can explain high fluidity of “B” sample. Thus, we considered more deeply concerning the correlation between chemical structure and plastic phenomena. 12-2

Coal Structure and Caking Property of Coal Oxidized at 373-673K

Hiroshi Ota, Takayuki Takarada, Gunma University, JAPAN

Low-temperature oxidation is a well-known but important process to change the caking property of coal. In this paper, we aim at investigating the mechanism of coal oxidation and the effect of oxidation treatment on the caking property. Particle size of coal sample showed a pronounced effect on the oxidation reaction. The oxidation reaction occurred more severely in the outer layer of coal particles than inside the coal particles. FT-ir was used to characterize the oxidized samples, and it was observed that carbonil functional group (C=O and COOH) and ether functional group (-O-) were the main products formed during the oxidation. The isotope 18O2 was used to trace the dynamics of the oxygen inherent in coal and that absorbed during oxidation. A mobile hydrogen in coal oxidized was measured by the reaction with anthracene at 693K. It was found that during the oxidation treatment, not only the oxygen adsorption occurred on the coals but also the reaction took place between oxygen and the hydrogen in coal with the release of H2O (m/z=20), and the two interactions may change the chemical bonds and the amount of hydrogen in coal and thus affect the caking property of coal. 12-3

Micro-Structural Analysis of Coke using the Overlaying Mesh Finite

Element Method

Asakuma Yusuke, Soejima Munetaka, Yamamoto Tsuyoshi, Aoki Hideyuki, Tohoku University, Miura Takatoshi, Itagaki Shozo, NKK Corporation, JAPAN

In order to clarify the bulk breakage mechanism of metallurgical coke in blast furnace for permeability, the overlaying mesh finite element analysis using global and local mesh that overlies each other, multi-level modeling analysis considering both macro and micro-structure simultaneously is applied for complex micro-structural geometry such as coke. We introduced the stress intensity factor, which is criterion of stress concentration around the crack tip, from displacements of singular points by the template mesh putting on the crack tip and evaluated characteristics of fracture for high-strength coke. The numerical results show that the stress intensity factor (K_I) is dependent on porosity (e) linearly and then we proposed the following equation considering a shape parameter (C) and the stress intensity factor (B) at e=0. K_I =B(1-Ce) This equation shows that the stress intensity factor decreases with porosity because principal stress around pores in the neighborhood of the crack tip becomes larger and pores prevent stress around the crack tip from concentrating. This negative effect of relaxation becomes larger as porosity increases. Namely crack development is governed by porous structure. Here the parameter C is a specific value, it depends on a pore shape and does not depend on a crack length. Also we investigated effects of other micro-structure, for example pore number density, inert, deposit carbon and open or closed pores etc. on the stress intensity factor by means of application of digital image analysis to the overlaying mesh method. As a result, micro-structure around the crack tip influences the crack growth and direction of crack propagation. It is necessary for coke quality to estimate mechanical properties from micro-structural point of view. We conclude that this numerical analysis is very useful for estimation of coke quality and available for other mechanical properties of microstructure.

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12-4

Abrasion Resistance of Cokes Made From Blends that Use Low Volatile Coals

Richard Sakurovs, Elizabeth Gawronski, Lindsay Burke, CSIRO Division of

Energy Technology, AUSTRALIA

The aim of this work was to isolate some of the factors that affect the prediction of the properties of cokes made from blends. Cokes were made from a number of blends of Australian coals prepared to the same nominal rank and fluidity but with different compositions. It was found that when low volatile coal was present in the blend there was a marked decrease in the resistance to abrasion as measured by severe abrasion tests, such as ASTM hardness, although no other indices were significantly affected. It was hypothesised that the cokes containing this coal flake on extended abrasion, owing to the relatively large domain sizes in the coke generated by this coal, but that this form of abrasion had no effect on strength or reactivity. This proposed paper reports on results of studies testing this proposed mechanism of abrasion of the cokes. Size distribution studies and petrographic analysis of the fine material support this explanation. The implications of this finding on the relationship between the results of abrasion tests and the performance of cokes in a blast furnace will be discussed.

SESSION 13

COAL GEOSCIENCES & RESOURCES-III

13-1

Signature Curves: The Future of Coal Petrography?

Helen Beath, Graham O’Brien, Joan Esterle, CSIRO Exploration and Mining, Barry Jenkins, Kwan Technology, AUSTRALIA

Since the development of image analysis systems over 30 years ago, there have been numerous attempts to apply this technology to coal petrographic analysis. Considerable improvements in video cameras and computers have improved image quality (32 grey levels to 256 grey levels) and made it possible to manipulate and store images. However, imaging systems have not yet been a commercial threat to manual methods. CSIRO divisions of Exploration and Mining and Minerals, via an ACARP funded project, have developed a robust system for the analysis of single seam coals. A total systems approach was used to improve sample preparation, calibration of the whole image and image processing. As a result, accurate and reproducible results have been produced for a large suite of coals. An imaging system produces a vast amount of data that requires manipulation to determine maceral group reflectance ranges, mean vitrinite reflectance value and maceral group percentages. Manual reflectance data, usually of vitrinite only, is commonly presented as a histogram. As image analysis data consists of reflectance values from all components present picking exact boundaries between maceral groups is difficult when these data are plotted as a histogram. Alternatively plotting the image analysis data as a cumulative frequency plot yields a signature curve or ‘fingerprint’ of a coal that allows the maceral group boundaries to be determined from the inflection points. This process has been automated through the use of a spreadsheet, thus removing operator bias and improving the accuracy of picking the inflection points. American, Australian and other coals were analysed to test the robustness of the system. Current refinements of processing individual grains within each image separately and improved delineation of liptinite from dark mineral matter will not only improve the system but also improve its capacity to analyse blends. This system has the potential to become a standard method for routine analysis and hence compete with traditional manual methods. 13-2

Coalbed Methane: The coming Important Fuel and Chemical Engineering

Materials in China

Xie Jingxuan, Ouyang Yongming, China University of Mining & Technology, P. R. CHINA

The resources of the coal-bed methane abound in China. The amount of coal-bed methane resources is about 3.5×1013m3 within underground 2000m, which is equivalent to 4.5×1010 t standard coal. Coal-bed methane keeping in coal seam and rock seam nearby is a kind of natural gas generating and storing naturally,

and is composed of many kinds gases, mainly CH4. As a kind of clean energy, coal-bed methane has its advantages of high caloric, low pollution, and easy to use. According to the requirement of both clean energy and environmental protection China government have attached great importance to the development and utilization of coal-bed methane. A series of preferential policies are making up one after another. Recent years, coal-bed methane is used as civil fuel, power generating fuel and mobile fuel etc. in China. The research on the coal-bed methane as fuel is developing rapidly, and some achievements and satisfactory progresses have been made, which laid a solid foundation of utilizing coal-bed methane still further. Coal-bed methane would substitute partially for coal as fuel and chemical engineering material in China due to its cleans and high efficiency. 13-3

Technical Developments in German Hard Coal Mining

Harald Jurecka, Bernd Tönjes, Deutsche Steinkohle AG, GERMANY

Deutsche Steinkohle AG is European Union`s biggest producer of hard coal. To improve profitability, DSK has continuously increased output per working face over the past few years. These results were only possible, however, thanks to the continued development and use of innovative mining technology, the use of largely standardised equipment and the consistent planning of these workings from the face to the shaft. The technical highlights include, for example, the development and use of new generations of winning equipment (plough and drum shearer), standardised conveyors and standard shield-type supports of the groups I-IV. In addition to this technical modernisation, the downstream "infrastructure" has also been improved by creating more efficient conveying and hydraulic/energy supply systems. Future requirements for even more efficient working faces can only be reliably satisfied if special boundary conditions are observed. These include raising the drivage performance by developing and modernising roadheading systems and the continued use of high-efficiency rockbolting support systems for great depths. 13-4

Distribution of Organic Nitrogen in Australian Coals

Lila W. Gurba, CRC for Coal in Sustainable Development, AUSTRALIA

Nitrogen is a minor but an important parameter in coal characterisation and utilisation. Nitrogen in coal contributes to nitrogen oxides formation under certain combustion conditions and these are related to photochemical smog formation. As reported from many different sources, coal contains 0.2 to 2.5% N in dry matter, although coals with in excess of 3% N are also reported. The distribution of nitrogen in Australian coals, particularly in the individual coal macerals, is poorly understood. This paper aims to investigate some of the geological factors controlling the distribution of nitrogen in eastern Australian coal basins, based on the results of ultimate and electron microprobe analyses. The study focuses on iso-rank coal mainly of high and medium volatile bituminous rank in the Gunnedah Basin (NSW), although data from higher rank coals will also be discussed from the Sydney, Gloucester and Bowen Basins. The nitrogen content in individual coals is assessed in relation to coal rank, coal type and depositional environment. Something Old: The determination of nitrogen in coal industry is typically based on ultimate analysis of whole coal samples. The whole coal represents a mixture of different coal macerals and mineral matter present, and the input of individual macerals to the average sample chemistry is not known. Over 400 proximate and ultimate analyses have been evaluated in this study, the majority of them with known petrographic composition. The results have shown the influence of coal type and depositional environment on the nitrogen content of the whole iso-rank coal. The values for nitrogen (dry, ash-free basis) obtained for vitrinite-rich coals, deposited in the lower delta plain facies, or coals deposited under marine influence, are higher (on average 0.5 up to 1%) than those in inertinite-rich iso-rank coals deposited in more fluvial-dominated environments. Something New: The contribution of individual coal macerals to the total ultimate nitrogen was investigated using a special light-element electron microprobe technique. Previous applications of the electron microprobe to coal, although successful for other light elements (carbon, oxygen), have shown some limitations with nitrogen determination. Supported by a research grant from the Australian Academy of Science, an experimental procedure was developed that has improved the detection limit for nitrogen using the electron microprobe. A series of coal samples representing the eastern Australian coal basins (Gunnedah, Gloucester and Sydney Basins) and the San Juan Basin (USA) has been analysed for C, O, N and S(O) in individual coal macerals. The results up

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to date indicate that inertinite macerals have the lower nitrogen (and organic sulphur) contents than vitrinite and liptinite macerals in the same coal sample. The highest values for nitrogen and organic sulphur were recorded from liptinite and liptinite-rich desmocollinite. In some cases, the nitrogen content of inertinite macerals such as fusinite and secretinite was below 0.5%, while the nitrogen in liptinite (sporinite) was about or above 3%. Implications for Coal Utilisation Since the proportion of nitrogen in inertinite-rich coal amounts less than in vitrinite-rich coals, the emission of its oxides during combustion may be less from inertinite rich coals. As being one of the acid-generating gases from coal combustion, it is essential to reduce the emissions of nitrogen oxides as much as possible. 13-5

The Impact of Geotechnical Factors on Secondary Extraction: Northern

Witbank-Highveld Coalfield, South Africa

Lesley Sharon Jeffrey, CSIRO, SOUTH AFRICA

Background Large areas of the Northern Witbank-Highveld Coalfield, South Africa have been mined in the past using bord and pillar methods, leaving significant amounts of coal in pillars and as floor or roof coal. Improvements in machinery and technology now allow extraction of previously unmineable coal. However, the constraints on secondary extraction imposed by geotechnical factors, and related safety aspects, have not yet been investigated. The aim of this study is to identify and quantify these factors for open cast and underground mining. Methodology The identification and quantification of the factors is a lengthy iterative process, achieved through continuous consultation with other researchers, colliery personnel, head office representatives and additional information from international secondary extraction operations. The initial literature review (Jeffrey, 1999) revealed that there is no published information concerning geotechnical factors pertinent to secondary extraction, although the effects of these factors on primary extraction have been considered. Ellison and Thurman (1976) address the issue of geotechnical factors in a generalised form, while Fettweis (1997) deals with the specific geological factors that have geotechnical implications. Although Dunrud (1998) refers to conditions and tests that are required for primary underground extraction, these remain applicable for secondary extraction, in particular with regard to the various effects of primary extraction stresses. The methodology involves six steps: Step 1: Identification of factors specific to the Northern Witbank-Highveld Coalfield, Step 2: Assigning each factor to one of three groups and a code within each group, Step 3: Assigning each factor to a class, Step 4: Categorization of these factors as fixed or variable (uncontrollable or controllable during mining respectively), Step 5: Quantification of each factor for mining method selection and for open cast and underground operations (quantifications range from 0 = low to 10 = high according to their negative impact) and Step 6: Quantifying the impact of each factor as major (≥ 7), moderate (5 ≤ 6.9) or minor (≤ 4.9). Factors and their impact Ten classes (Jeffrey, 2000a) incorporating 55 geotechnical factors (Jeffrey, 2000b) impacting on secondary extraction are identified. These classes have influence in a number of different areas such as rock mass behaviour, roof support and explosions and ignitions. Some factors are controllable during mining, while others are not. 14 factors are shown to have impact when selecting a mining method, five have impact on open cast secondary extraction and eight factors impact on underground secondary extraction. Conclusions The interaction of a number of geotechnical factors during mining is shown to be critical e.g. undulations in the palaeotopography, combined with the orientation of the high wall, major joint directions and pillar orientation can lead to unexpected sloughing of the high wall (Jeffrey, 2000a). Factors cannot be directly compared from one mining operation to the next, due to the variability in the intensity, frequency or extent of each factor. The management of factors arising due to the geology is shown to be more important than the geology itself. For example, adequate support of known roof discontinuities during stooping can prevent roof and pillar failure. In the open cast example given in the

previous paragraph, more rigorous planning of the strip layout, taking those geotechnical factors into consideration, could have reduced the likelihood of sloughing. However, the risks associated with geotechnical factors must be balanced against other mining needs such as rate of extraction and economic viability of one layout versus another. The successful management of geotechnical factors is a multi-disciplinary exercise, incorporating informed input from geologists, rock engineers, mining engineers and mine planners, while continually taking cognizance of constraints on quality and economic viability.

SESSION 14

GASIFICATION: TECHNOLOGY ADVANCES-I

14-1 Integrated HTW Gasification for Optimised IGGC Power Plant Concepts

Bernd Meyer, Dmitry Korobov, Freiberg University of Mining and Technology,

GERMANY

Realised Integrated Gasification Combined Cycle (IGCC) power plants show relatively low efficiencies at too high capital and operating costs. With the optimised IGCC process, the simplified fuel gas cleaning at higher temperatures and the advanced gas turbine, the net efficiency of power generation is expected to reach 55 % (LHV basis) and higher values within the next 10 to 15 years. The 55 % IGCC power plant would be the next large milestone in the development of the power plant technology. The changig power market and the ongoing environmental standards force a further simplification of the IGCC technology, particularly the cost reduction and increase of the reliability. The gasification with oxygen instead of air offers considerable advantages. The requirements for gas clean up become well lower, also with regard to the co-utilisation of biomass and wastes. In addition, the long term option of synthesis gas production remains open. For lignite, a technically matured gasification concept of HTW process is available. Principal possibilities for further simplifications in key process steps of the gasification and the gas clean up are presented. A further developing focus area is the process integration and the combination of gasification steps. With a concept study of a 55 % IGCC power plant, the efficiency potential of concept simplification for the HTW process are closely investigated. For instance, thermodynamic and economic analysis of the integrated HTW process for German lignite (gasification with integrated warm gas filter and dry gas cleanup by partial oxidation) is presented. 14-2

Partial Gasification Combined Cycle Technology: A Practical Pathway for Clean Coal Advancement

Robert Giglio, Mani Seshamani, Zhen Fan, Foster Wheeler, USA

Coal is the biggest contributor to our global electricity production today and an important energy resource needed to meet our growing energy needs of tomorrow. But, its continued use is in conflict with our ever-growing environmental concern. To fully unlock its value, generation technologies must be developed to reduce coal’s environmental impact while maintaining its very competitive generation economics. Foster Wheeler has applied its gasification and combustion know-how to develop an advanced coal fueled combined cycle power plant technology. The clean coal technology named Gasification Combined Cycle (GCC) integrates fluid bed coal gasification, advanced gas turbine and supercritical steam technology (PC or CFB) to achieve a highly efficient solid fuel generation plant. It is expected that GCC will be able to achieve the highest efficiency for solid fuel power generation. Plant designs are on the drawing board now that can achieve efficiencies of 45% and beyond, exceeding 10 percentage points above today’s commercial coal technologies. Unlike other advanced coal technologies which rely on extensive gas cleaning to achieve low air emissions of selected pollutants, the GCC technology emphasizes high efficiency to achieve substantial reductions in all plant emissions (air, solids, effluents) including the greenhouse gas-carbon dioxide. Since less fuel is burned for each megawatt of electricity produced, the

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emissions are reduced at the front end of the process by not generating the pollution in the first place. GCC is expected to emit 30-50% fewer emissions than today’s coal plants. Another important goal for GCC is to meet the bar for near term commercial success. Technology features such as low temperature fluid bed gasification, a streamlined process minimizing components, and utilization of proven technologies such as PC and CFB allow GCC to achieve the reliability, fuel flexibility, competitive economics and a low risk profile needed for commercialization. A full-scale demonstration project of the GCC utilizing CFB combustion technology is expected to begin this year supported with DOE funding. 14-3

Improving Refractory Service Life in Slagging Coal Gasifiers

Cynthia P. Dogan, Kyei-Sing Kwong, James P. Bennett, Richard E. Chinn, U.S. DOE/Albany, USA

Current generation refractory materials used as liners in slagging gasifiers employed in Integrated Gasification Combined Cycle (IGCC) fossil fuel power systems typically have service lives of no more than two years, limiting the reliability and cost effectiveness of gasification as a means to generate power. The unacceptably short service life of the refractory lining results from exposure to the extreme environment inside the operating gasifier, where the materials challenges include temperatures to 1650 °C, thermal cycling, alternating reducing and oxidizing conditions, and the presence of corrosive slags and gases. Compounding these challenges is the current push within the industry for fuel flexibility, which can result in slag chemistries and operating conditions that vary widely as the feedstock for the gasifier is supplemented with alternative sources of carbon. At the Albany Research Center, we are exploring ways to enhance gasifier reliability through the development of improved refractory liner materials. In this presentation, we will first discuss why conventional refractory materials are so quick to fail in a gasifier environment, and then explore the ways in which refractory performance can be improved. Emphasis in this talk will focus on the refractories employed in slagging gasifier systems which utilize coal as the primary feedstock. 14-4

Evaluation of Innovative Fossil Cycles Incorporating CO2 Removal

Ronald L. Schoff, Jay S. White, Thomas L. Buchanan, Parsons Infrastructure &

Technology Group Inc., Gary Stiegel, U.S. DOE/NETL, Neville A. H. Holt, George Booras, Electric Power Research Institute, Ron Wolk, Wolk Integrated

Technical Services, USA

The coal-fired option for new electricity generating plants remains important to utility generating companies that have been historically dependent on coal for the bulk of their power generation. Recently, however, there has been growing concern about the effect of power plant CO2 emissions on the global environment. There have been indications that CO2 emissions may be curbed by law in the near future. A natural gas-based power plant will produce less CO2 per kW of power output compared to a coal-based plant with the same net plant power output. This is due to the lower carbon-to-hydrogen ratio of natural gas as well as its power-generating efficiency compared to coal-based systems utilizing the same power generation equipment. As a result, the cost of CO2 removal systems for natural gas power plants will always be less than for conventional coal-fired plants. The coal plant total investment cost target may therefore have to be reduced if CO2 removal systems are added to future power generation systems. However, in gasification based systems, CO2 can be removed prior to combustion power generation at lower cost than post combustion CO2 removal. Innovative coal gasification based systems may therefore be the most cost effective coal plants if CO2 removal is required. The objective of the work presented in this paper is to evaluate preliminary designs of several advanced coal-fired power plants to determine whether they have the potential to be competitive, in the period after year 2010, with natural gas combined cycle power plants of the “G/H” class or conventional pulverized coal-fired power plants. Each power plant concept evaluated is configured with a CO2 removal system. For the advanced coal-fired power plant designs that meet the competitive cost targets, DOE will define the R&D effort required to develop and demonstrate the technology to be a commercially attractive alternative. This paper is intended to update work that was originally reported at the 2000 Pittsburgh Coal Conference. Since the last presentation, additional cases have been run and analyses performed. In addition, changes may have been made to some of the cases in the last year.

14-5

An IGCC Design for CO2 Capture

Luke F. O’Keefe, Richard C. Weissman, Richard A. De Puy, Texaco Power & Gasification International, John M. Wainwright, General Electric Power

Systems, USA, John Griffiths, Nathan East, Jacobs Engineering, England The first Integrated Gasification Combined Cycle (IGCC) plant began producing electricity in 1984. Today, there are more than ten plants in operation or advanced stages of development. With increasing attention to emissions of greenhouse gases like carbon dioxide, it is important to find a cost-effective way to efficiently produce electricity from coal and reducing the volumes of CO2 per unit of power produced. Texaco Power and Gasification, General Electric Power Systems, and Praxair evaluated the technical feasibility and economic viability of harnessing Texaco Gasification Power Systems with General Electric's 9FA Combined Cycle Power Generation System. This paper will report the results of combining these highly efficient technologies along with a validation of those results by an EPC contractor. The paper will divulge, among other findings, gross and net power outputs, thermal efficiency, and capital cost. The combination of improvements in plant integration, higher overall turbine efficiency, and greater output in a single train configuration make the study team confident that this coupling of highly efficient technologies will become the next generation IGCC.

SESSION 15 PULVERIZED COAL COMBUSTION-III

15-1

Interaction of Blast Furnace Cokes in Pulverised Coal Flames

Brian M. England, Jeffery C. Keating, Mark B. Mason, Harold Rogers, BHP

Minerals Technology – Newcastle Laboratories, AUSTRALIA

In the combustion of pulverised coal in the blowpipe-tuyere-raceway region of the ironmaking blast furnace the coal combustion is incomplete in the time available between the point of injection and the coal char reaching the burden surface at the periphery of the raceway. (Typical transit time estimates are of the order of 20 milliseconds.) Therefore, char solids are swept into the furnace burden with the potential for decreasing bed porosity and lowering burden permeability and consequently lowering furnace productivity. The constitution of the materials from areas likely to be affected by char accumulation obtained through tuyere probing, or from furnace dissections, is sufficiently complex that identifying the interactions between pulverised coal char and coke, the principal burden component, is difficult. To investigate the possible interactions between pulverised coal chars and blast furnace coke, coke cylinders preheated to approximately 1500 oC under an argon atmosphere were exposed to the plume of combusting pulverised coal, developed within a combustion test apparatus that provides a close geometric similarity with the blast furnace situation. Coal is injected into a hot air blast (1200 oC) at the inlet to a tuyere of 70mm diameter and the jet subsequently expanded into a combustion test chamber of 300mm diameter. Equivalent coal injection rates of 150 kg/tHM and blast oxygen enrichments of 3% were used throughout. The transit times between the point of injection and the position of the coke test piece are estimated from numerical modeling to be of the order of 16 to 18 milliseconds. Cokes covering three pilot oven cokes of blast furnace quality in terms of cold strength (Japanese Drum DI150/15), but differing in terms of the CSR and CRI test results, a production blast furnace coke and a blast furnace bosh coke (raked from a tuyere during a maintenance hold), were exposed to pulverised coal flames developed with coals ranging from 36 to 12%(db) proximate volatile matter and with a range of ash composition. Detailed investigation of the “reacted coke” cylinders using scanning electron microscopy coupled with EDS analysis indicated that no coal char adhered to the surface of the coke cylinder, either as char trapped within the surface pore openings, or adhering to slag or fused mineral matter globules developed on the exterior surface. The composition of the surface mineral matter bodies, when compared to the field of the coke’s internal mineral matter, tended to show some movement toward either enrichment in silica or, enrichment in Al2O3. In the majority of instances where Al2O3 enrichment of the surface mineral matter was noted, ferrosilicon was also noted as being present on the surface of the reacted coke cylinders. [Current analysis is directed at understanding the processes and chemical controls on the identified trends in the chemistry of the surface mineral matter bodies.]

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15-2

Combustion Rate of Single Vitrinite Particles

J. Chen, J. Pohl, V. Rudolph, University of Queensland, D. Harris, CSIRO Energy Technology, AUSTRALIA

This paper describes the measurements of the combustion rates of individual vitrinite particles sampled from five coals of different rank. Vitrinite particles, 100 - 150 m in size, are heated in air at approximately 104 K/s and burnt at a constant temperature of 1800 K. The particle were heated by a laser whose power is controlled via two-color pyrometer measurements. The surface temperature and weight loss of the maceral particles are measured simultaneously during combustion to completion. Video cameras viewed the burning particle from two different directions and recorded the change in particle size during burnout. These measurements show that the rate of burnout of vitrinites particles change through the burning process and is inversely proportional to the fraction of residual coal unburned. The reaction rate decreases as mean reflectance changes from 0.4 to 1.35 (%, in oil). 15-3

Charactertization of Mineral Transformations in PF Combustion by

Dynamic High-Temperature X-Ray Diffraction Analysis

David French, Les Dale, Chris Matulis, John Saxby, Peter Chatfield, Harry.J. Hurst, CSIRO Division of Energy Technology, AUSTRALIA

X-ray diffraction has been an invaluable tool for the characterization of coal mineral matter as most minerals have a unique diffraction signature which can be used both for identification and quantification of mineral abundances. The capability to perform dynamic X-ray diffraction analysis under controlled atmosphere conditions and variable heating rates to 2400oC (1600oC in oxidising atmospheres) provides a powerful new tool for the study of coal mineral matter reactions at high temperature. Used in conjunction with SIROQUANT, a quantitative X-ray diffraction package developed by CSIRO Division of Energy Technology, quantitative abundance data can be obtained not only for the crystalline phases but also for any solid or liquid amorphous phase which may be formed. An obvious application of high-temperature X-ray diffraction is the investigation of the mineral reactions that occur during coal combustion in power plant boilers which lead to the formation of slagging and fouling deposits. Previously, the nature of these reactions has been deduced either from a study of the chemistry of the reaction products or from phase-equilibria modeling. By heating the sample under controlled conditions which approximate to those prevailing during pf combustion, the mineral reactions can be studied dynamically and the effects of parameters such as differing heating rates and variable gas atmospheres evaluated. The results from dynamic high temperature X-ray diffraction identify the critical mineralogical transformations which occur during pf combustion and, when used in conjunction with other advanced characterisation methods such as thermomechanical analysis (TMA), provide new insights into the behaviour of cola minerals matter in pf combustion. The results of dynamic high-temperature X-ray diffraction analysis of a suite of well-characterized Australian thermal coals will be presented with a discussion of the critical mineral transformations. and a comparison of the XRD data with the results of FACT thermodynamic modeling. The significance of the observed mineralogical transformations with respect to thermomechanical behaviour and ash fusion temperatures will also be outlined. 15-4

Mineralogical Changes in Selected Australian and Overseas Coals in Boiler

Simulation Test and Improved Ash Fusion Test

Hakan Kahraman, Adrian Reifenstein, ACIRL, Nick J. Calos, Gavin Miller, AGR Science & Technology Pty Ltd., David Page, University of Queensland,

AUSTRALIA

A suite of selected Australian and overseas coals that were previously studied in ACARP Project C3097 was investigated for the practical applicability of the Improved Ash Fusion Test (IAFT). The ashes of the coals and their slagging panel deposits and improved ash fusion products were analysed using quantitative X-ray diffractometry (QXRD) and X-ray flourescence spectrometry (XRF). The objective was to ascertain if the mineralogical changes that were evident in the slagging panels were also apparent, both qualitatively and quantitatively, in the samples from the improved ash fusion test. The shrinkage traces from the improved ash fusion test have been explained in terms of events of liquid formation at the temperatures

predicted by phase diagrams and are related to the ash chemistry. Quartz and kaolinite were found in all low temperature coal ash samples as major components, with anatase, gypsum, siderite and illite-smectite (IS) as accessories. Minor analcite or leucite and trace jarosite or pyrite could be found in some coals. However, no trace of phosphate minerals such as apatite could be identified with any certainty. These minerals, except for apatite, were included in the quantitative Rietveld refinement procedure. Quartz, mullite, cristobalite, hematite, magnetite, gypsum, anatase and glass were found in both slagging panel deposits and improved ash fusion products. The IAFT demonstrated that it would be useful to rank the coals in terms of their performance for slagging when compared against operating power plant data. The test successfully predicted the troublesome coals in the combustion testing. 15-5

Simultaneous Removal of SOx and Halogens under Pulverized Coal Combustion Added Fine Limestone

Yoshihiko Ninomiya, Zhang Lian, Atsushi Sato, Chubu University, JAPAN

Studying on the fate of sulfur sorbent in coal combustion is necessary for improving the process efficiency of combustion, especially as the requirement of energy being increased rapidly, more low-grade coals with high sulfur and high ash contents are being used directly in the electric utility power plants. In this paper, combustion of three coals was carried out in the drop tube furnace (DTF). Limestone is mixed with coals for capturing sulfur and halogens in the furnace. XRD is used to analyze the crystalline phases in the fly ash, SEM-EDX used for structure observation while CCSEM used for determining the particle size distribution and composition of ashes on the basis of particle-to-particles. A novel calcium-based phase definition was developed to probe the fate of added limestone in the combustion. The mechanisms determining transformation of limestone is discussed here. Three Chinese coals (YZHS coal (Sulfur content= 5.7wt%), DT coal (S=1.7wt%), YZLS coal (S=0.6wt%)) used in this study have significant mineralogical composition and particle size distribution of minerals. The combustion experiment was conducted about the fuels that mixed coal and limestone (sulfur to calcium molar ratio is 1 to 3). The reactions of the added limestone with sulfur and minerals were evaluated by CCSEM analysis of fly ashes. YZHS coal has lower kaolinite content and bigger sized minerals than that of DT and YZLS coals. De-S and De-Cl ability of limestone depends strongly on the coal type. Though the molar ratio of Ca/S is 1.0, limestone shows higher De-S efficiency, ca. 89% for YZHS coal while for DT is only ca. 51% though Ca/S is 2.0(molar). This result indicates that part of added limestone is scavenged by minerals to form Ca Al-silicates, which apparently hampers the utilization of limestone. The particles having size 22.0mm (defined as fine particles) are rich in mixed Ca Al-silicates, while the particles >22.0mm separately locate in two zones, Ca-rich and Al-silicates. As time increases to 1.8s, there is an obvious shift of the composition from Ca-rich corner and Al-silicates towards Ca Al-Si center, the big-sized particles (>22.0mm) are mainly attributed to the agglomeration of melt Ca-S compounds with Al-silicates. DT coal is rich in Kaolinite, which has finer dispersion in the raw coal, while YZHS has lower content of Kaolinite, which shows bigger size. Combined with above results, it is apparently concluded that finer Kaolinite in DT coal facilitates scavenging reaction of Ca by Al-silicates, which, therefore, decreases the effective utilization of limestone, leading to a low desulfurization compared to that of other two coals.

SESSION 16 LOW-RANK COAL UTILIZATION-III

16-1

Effect of Catalyst Form and Concentration on the Reactivity of Chars from

a Victorian Brown Coal

Hongwei Wu, Chun-Zhu Li, Monash University, AUSTRALIA

The purpose of this study is to investigate the factors influencing the reactivity of chars from the pyrolysis of a set of Victorian lignite samples containing sodium in the forms of NaCl and sodium carboxylates. The H-form lignite was prepared by washing the raw lignite with 0.1M H2SO4 to remove the cations in the lignite. NaCl was then physically impregnated into the raw lignite to prepare a series of NaCl-loaded lignite samples with different NaCl contents. The Na-form lignite was prepared by ion-exchanging the H-form lignite with sodium acetate. These lignite samples were pyrolysed in argon in a thermogravimetric analyser at different peak temperatures. The reactivity of chars after pyrolysis was determined in situ in air at 400 °C by switching the gas from argon to air. The reactivity of chars seems to correlate with the sodium content in the chars when the sodium in the chars is below the holding capacity of the chars.

19

However, when the sodium in the char exceeds the holding capacity of the char samples, such a correlation disappears. The results indicate that the contents of catalysts in the chars are not the only factor governing the char reactivity. The forms of catalysts in the chars, which depend on the coal substrates and char forming conditions, are also an important factor. The effects of thermal annealing on char reactivity are also studied experimentally and will be discussed in this paper. 16-2

Flow Characteristics of High Temperature Eutectic Alkali Sulphate

Mixtures Containing Inert Silica Inclusions

Narongsak Tonmukayakul, Quoc Dzuy Nguyen, University of Adelaide, AUSTRALIA

Research into the effect of the liquid phase on fluid bed particle agglomeration during combustion of Australian low rank coals has become more and more prevalent over the past ten years. It has been well established that the liquid phase forms from mineral transformation that occur during high temperature combustion processes. It has been found that the alkali compound mainly sulphate mixtures of calcium; magnesium and sodium are the key components of the liquid phase. The amount of liquid phase that forms from these three compounds also increases with increasing temperature. If the operating temperature is high enough the molten liquid phase fully covers the solid ash particle, mainly silicate compound and become a suspension between solid-molten liquid phases. In this paper the rheological measurements and characterizations of an artificial mixture between silica oxide and alkali sulphate compounds has been tested at temperatures of 900°C, 1000°C, 1100°C and 1200°C. The experimental data was treated using several empirical rheological models and the effect of the compositions on the model parameters is discussed. Time dependent behavior of the suspension was also investigated and described. The rheological results are the basis for a further theoretical study. 16-3

Low Temperature Rapid Heating Steam Gasification of Brown and Sub-Bituminous Coals

Chihiro Fushimi, Atsushi Tsutsumi, The University of Tokyo, Jun-ichiro

Hayashi, Tadatoshi Chiba, Hokkaido University, JAPAN

The coal gasification is one of the most promising technologies for effective energy conversion in the 21st century. In the conventional coal gasification processes, the heat required for endothermic gas reaction is usually balanced by highly exothermic partial combustion/oxidation of coal. This combustion process at relatively low temperature reduces the thermal efficiency of energy conversion because of its large exergy loss. If the heat required for steam gasification is supplied by wasted heat from gas turbine or other the chemical processes, the low temperature level energy is accumulated in a form of hydrogen with carbonaceous resources. Since produced hydrogen is combusted at higher temperature than wasted heat, this process can act as a chemical heat pump, which upgrades lower temperature level energy to higher temperature level energy. Therefore, the thermochemical hydrogen production by steam gasification can significantly improve the overall thermal efficiency. The fundamental research on the reactivity of coal with the steam gasification was conducted at relatively low temperature (973-1173 K) at the heating rate of 100 K/s by using a newly developed thermogravimetric reactor. The steam with the carrier gas Ar was introduced into the reactor. The weight change of coal sample during the reaction was recorded on a personal computer at the time interval of 0.2 or 0.4 s. The gaseous products (H2, CH4, CO and CO2) were analyzed by a mass spectrometer and a high-speed gas chromatograph. The effects of temperature and heating rate on the gasification of Taiheiyo sub-bituminous coal (TH), Yallourn brown coal (YL) and Loy Yang brown coal (LY) were examined. It was found that Pyrolysis and steam gasification at the heating rate of 100 K/s completed within about 10 s and several minutes, respectively. The char of which yield was 50-70% on carbon basis in pyrolysis was converted into CO2 and H2 by the steam gasification. About 50-80% of coal energy was converted into hydrogen by steam gasification reaction. The initial rate constants of steam reforming of char at higher heating rate became larger because tar decomposition reaction was enhanced by the higher heating rate.

16-4

Steam drying –Changes in Lignite Structure at Different Drying Temperatures

George Favas, A L Chaffee, Monash University, AUSTRALIA

Steam drying is a process that utilises superheated steam to remove water from high moisture coals. Steam drying experiments were carried out at different temperatures (130°C to 350°C) at saturation pressure for each temperature in a batch autoclave for 30min. In the temperature range 130°C to 320°C the water content of the product decreased linearly with increasing temperature. Above 250°C loss of water was accompanied by loss of organic material due to decarboxylation and release of waxes and tars into the condensate. Temperatures above 250°C gave a larger decrease but at the expense of loss of organic material due to decarboxylation and the release of volatile material such as waxes and tars into the condensate. Changes in the coal structure from this process were analysed using a range of techniques including DRIFT spectroscopy, 13C nmr, acid-base titrations, ultimate and proximate analysis. The coal pore structure was characterised by mercury porosimetry, helium pycnometry and CO2 adsorption. The organic carbon content and the concentration of Na, Ca and Mg in the condensate were determined. 16-5

Effect of Irradiation by Accelerated Electrons on the Supramolecular

Organization and Reactivity of Coals

P.N. Kuznetsov, L.I. Kuznetsova, Ya Obukhov, Institute of Chemistry and Chemical Technology, RUSSIA, Y. Sato, Institute for Energy Utilization,

JAPAN

The effects of irradiation pretreatment with the beam of accelerated electrons on the composition of brown coal, its X-ray structural parameters, solvent swelling, tetrahydrofuran swelling ratio and the reactivity for the hydrogenation into the low molecular and soluble products were studied. The data obtained showed both degradation and crosslinking reactions to take place during the irradiation, degradation being the prevailing one at the low doses of 10-100 Mrads. After the most readily degradable cross-links have been decomposed, the radiation-induced polymerization becomes significant. It was shown that radiolysis polymerization can be prevented by using the appropriate solvent. The radiation induced effects on the hydrogenation were compared to those of conventional different chemical and mechanochemical pretreatments. The irradiation in the presence of polar ethanol solvent was shown to be the most beneficial pretreatment which greatly improved the reactivity of brown coal for the hydrogenation in tetralin solvent. Radiation effects are discussed in terms of the radiation-induced rearrangements within the supramolecular structure of organic matter of coal.

SESSION 17

GREENHOUSE GAS CONTROL & CO2 SEQUESTRATION-III

17-1

Study of Magnesium Rich Minerals as Carbonation Feedstock Materials for CO2 Sequestration

M. Mercedes, Maroto-Valer, Matthew E. Kuchta, John M. Andrésen, Yinzhi Zhang, The Pennsylvania State University, Daniel J. Fauth, Yee Soong, U.S.

DOE/NETL, USA

The greatest challenge to achieve no environmental impact or zero emissions in coal-fired power plants is probably greenhouse gases, especially CO2 emissions, that are inevitably associated with fossil fuel combustion. Mineral carbonation, that involves the reaction of CO2 with non-carbonate minerals to form stable mineral carbonates, has been lately proposed as a promising CO2 sequestration technology. This is due to the vast natural abundance of the raw minerals, the long term stability of the mineral carbonates formed, and the overall process being exothermic, and therefore, potentially economic viable. However, current mineral carbonation studies require prior pulverization of the raw minerals, long reaction times (>6 hours) and extremely high partial pressures at >115 atm. Consequently, mineral carbonation will only become a viable cost-effective sequestration technology through innovative development of fast reaction routes under milder regimes in a continuous integrated process. A selection of magnesium rich minerals was studied for use as carbonation feedstock materials. N2 and CO2 adsorption isotherms were used to characterize their surface properties and assess their potential as carbonation minerals. The carbonation

20

activity was quantitatively determined by the increase of the weight of solid products and the percent of stoichiometric conversion, and these results will be reported. 17-2

Novel Adsorbent for CO2 Capture Based on Polymer-Modified Mesoporous

Molecular Sieve of MCM-41 Type

John M. Andrésen, Xiaochun Xu, Chunshan Song, Bruce G. Miller, Alan W. Scaroni, Pennsylvania State University, USA

CO2 capture technologies are available commercially but are still energy intensive and relatively expensive. Consequently, new approaches for CO2 capture are needed for developing improved technologies. Adsorption is one of the promising methods that could be applicable for separating CO2 from gas mixtures. The present work is aimed at exploring novel adsorbent materials for selective CO2 adsorption. A mesoporous molecular sieve of MCM-41 type was synthesized, modified by loading a branched amine-type polymer and examined as a CO2 adsorbent. Mesoporous molecular sieve MCM-41 was hydrothermally synthesized from a mixture with the following composition: 50SiO2:2.19(TMA)2O:15.62(CTMA)Br:3165H2O, where the TMA and CTBA are tetramethylammonium and cetyltrimethylammonium, respectively. XRD and N2 adsorption confirmed that the as-synthesized material possessed MCM-41 structure. The polyethylenimine (PEI) modified MCM-41 (MCM-41-PEI) was prepared by impregnation. The PEI loading was about 33%, as determined by TGA analysis. The adsorption and desorption experiments were carried out on a PE-TGA 7 thermalgravimeter at different temperatures. Before measurement, the sample was heated up to 100 oC in flowing N2 and held at that temperature until there was no weight loss. The CO2 adsorption capacities of MCM-41, PEI and MCM-41-PEI were then measured. At 25 oC, the adsorption capacities of MCM-41 and PEI were similar. With an increase in temperature, the adsorption capacity increased for MCM-41-PEI but decreased for MCM-41. The adsorption capacity of MCM-41-PEI reached its maximum value at 75 oC, then decreased with further increase in temperature. The adsorption capacity of MCM-41-PEI was 7 times higher than that of MCM-41 at 75 oC. The high adsorption capacity can be ascribed to the PEI as well as the cage and high surface area of MCM-41. Desorption of CO2 was complete when the temperature was below 75 oC. For adsorption at 100 oC, only 70% CO2 desorbed. In summary, a new CO2 adsorbent composed of PEI-modified MCM-41 was developed. The CO2 adsorption capacity of MCM-41 was increased 7 times after modification with the PEI. The new CO2 adsorbent showed high CO2 adsorption capacity at relatively high temperatures. Further work is in progress. 17-3

CO2 Capture from PC Boilers with O2-Firing

John C. Molburg, Richard D. Doctor, Norman F. Brockmeier, Argonne National

Laboratory, Sean Plasynski, U.S. DOE/ NETL, USA

The U.S. Department of Energy (DOE) is investigating CO2 recovery from fossil-fuel-based power cycles as a greenhouse gas mitigation strategy. Given that the most common such cycle is the conventional pulverized coal-fired plant, a system that could be retrofit to such boilers for CO2 recovery would have broad applicability. Argonne National Laboratory (ANL) was an early investigator of such systems, proposing them as a source of CO2 for enhanced oil recovery. To improve the economics, the ANL process substituted oxygen for air as the oxidant and employed flue gas recirculation for tempering combustion. Recently, TransAlta investigated the economics and feasibility of such a retrofit on their 300 MW Sundance Unit 1 plant. While technically feasible without major boiler modification, the economics of the retrofit are unfavorable unless incentives or requirements for CO2 emission reduction are implemented. The DOE felt that additional investigation of the costs and merits of this technology were needed to adequately understand its potential application to US power plants. The CO2 recycle system reviewed for Trans Alta is not burdened by SO2 control because the coal used contains only 0.2 weight percent sulfur. The situation for US coals is significantly different, because of the relatively high sulfur content. Hence, an important part of this investigation is the interaction of sulfur control with the CO2 recycle. By extracting a portion of the recycle prior to sulfur removal, the sulfur removal system costs may be reduced, though there is increased concern for corrosion potential as SO2 is concentrated in the flue gas. We have also investigated the possible impact on flue gas desulfurization of high CO2 concentration in the flue gas and have reviewed an alternative sulfur removal system that produces low volume sulfur byproducts.

17-4 Reactor Design Considerations in Mineral Sequestration of Carbon Dioxide

M.T. Ityokumbul, S. Chander, Pennsylvania State University, W.K. O’Connor,

D.C. Dahlin, S.J. Gerdemann, Albany Research Center, USA

One of the promising approaches to lowering the anthropogenic carbon dioxide levels in the atmosphere is mineral sequestration. In this approach, the carbon dioxide reacts with alkaline earth containing silicate minerals forming magnesium and/or calcium carbonates. Mineral carbonation is a multiphase reaction process involving gas, liquid and solid phases. The effective design and scale-up of the slurry reactor for mineral carbonation will require careful delineation of the rate determining step and how it changes with the scale of the reactor. The shrinking core model was used to describe the mineral carbonation reaction. Analysis of laboratory data indicates that the transformation of olivine and serpentine are controlled by chemical reaction and diffusion through an ash layer respectively. Scanning electron microscope (SEM) with wavelength-dispersive X-ray microanalysis (WDX) confirms these observations. Rate parameters for olivine and serpentine carbonation are estimated from the laboratory data. The use of these findings for improved process design is discussed. 17-5

Co-Burning Manufactured Gas Plant s Clean-Up Residues in Utlilty Boilers

Kevin L. Hylton, Rochester Gas and Electric Corporation, Ishwar P. Murarka,

Ish, Inc., USA

With the assistance of the Electric Power Research Institute, three public utilities in the United States performed pilot studies to evaluate the performance of pulverized coal boilers as a means of destroying organic contaminants contained in coal tar and tar-impacted soils. The tar and impacted soils were excavated by those utilities as part of the efforts to remediate sites of former manufactured gas plants (MGPs) within their respective service territories. Unit performance and the effectiveness of the technique as a thermal treatment system were characterized by evaluating boiler efficiency, flue gas and wastewater quality, destruction removal efficiency, ash generation rates and quality, and impacts on fuel conveyance and processing systems. Economic analyses were also performed at the conclusion of the pilot studies. This paper contains a description of the three boilers of varying configurations as are the various systems used to blend the tar and tar-impacted soils with the fuel coal, and finally how the blended fuel materials were fed into the boiler. In one case, pilot-level testing was conducted following the completion of an extensive laboratory scale testing by the boiler manufacturer to gauge expected erosion and wear characteristics of the tar/coal and soil/coal blends. For this test, pilot scale results are compared to the laboratory results as a means of evaluating the predictive accuracy of the laboratory tests. Overall results of longer term, production level co-burning are also briefly described. Economic analyses resulted in a unit cost for thermal treatment that can be compared to available alternative thermal treatment options. The economic, operational and performance observations generated in these test burns provide reliable data to power generators and environmental managers on co-burning in a pulverized coal boiler for a thermal treatment of MGP site clean-up residues.

SESSION 18 NON METALLURGICALCOAL

18-1

Carbon Nanotubes from Coal

Michael A. Wilson, Craig Marshall, University of Technology Sydney,

AUSTRALIA

Materials which pack in the form of small rod shapes are of technological interest since they can exhibit considerable strength. In the past decade we have seen an enormous level of activity in nanostructured materials fueled in particular by carbon nanotubes which are closed elongated structures of pure carbon. They have application in nanoelectronics as conductors, semiconductors and as transistors. They can also be used for hydrogen storage. In our laboratory we have made efforts to synthesise these materials from sources other than graphite and in particular coal. The work complements a similar program in our laboratory in synthesising fullerenes from coal. Because coal is a molecular solid, and graphite is a lattice solid, there are distinct differences in processing mechanisms between the two materials. Unlike graphite, coal has weak bonds,

21

and hence can proceed through a mechanism which does not involve single carbon units. Thus the products can differ from those from graphite. Nanotubes come in a variety of types which include multi walled and single walled forms. Each form can have a variety of diameters or can arise from different ways of rolling the graphite sheet from which they derive. The latter forms are called armchair, chiral and zig zag. Additives such as naphthalene and cobalt can affect the nature of the product formed. The presence of other elements in coal produces a different type of nanotube distribution. Both iron and sulphur are important. Coal also produces other products such as microfilaments and polycyclic hydrocarbons. 18-2

The Difference of Shape-Selectivity of Zeolites in the Isoproylation of

Biphenyl

Yoshihiro Sugi, Yoshihiro Kubota, Shogo Tawada, Ranjeet Kauer Ahedi, Rajib Bandyopadhyay, Mahuya Bandyopadhyay, Akira Ito, Kohji Sakakibara,

Chikayo Naitoh, Gifu University, Taka-aki Hanaoka, Takehiko Matsuzaki, National Institute of Advanced Industrial Science and Technology, JAPAN

The polynuclear aromatics such as naphthalene and biphenyl are highly valuable chemicals obtained as by-products in dry coking and hydrogasification of coal. They are important intermediate for advanced materials, and key technology for them is their functionalization. The shape-selective alkylation is the promising way to the purpose. Recently, we found H-mordenite (MOR) is highly selective for the isopropylation of biphenyl and naphthalene [1]. In this paper, we describe the potentiality of zeolite for shape-selective catalysis in the isopropylation of polynuclear aromatics.

Figure shows the selectivity of 4,4’-diisopropylbiphenyl (4,4’-DIPB) in the isopropylation of biphenyl over zeolites. Shape-selective catalysis to yield 4,4’-DIPB preferentially was observed only over one-dimensional zeolites, MOR, CFI, AFI, and, MTW. The selectivity of 4,4’-DIPB for MOR is the highest among them: this means that its pores fits the most to the transition state composed of biphenyl, propylene, and acid sites. The pores of other zeolites are less fitted for the catalysis than MOR. On the other hand, FAU and BEA show low selectivity of 4,4’-DIPB because they have wide supercages inside pores.

Detailed features of the catalyses are also discussed at the conference. 18-3 Alkali Ash Material (AAM) a New and Novel Material Made from Fly Ash

Hossein Rostami, William Brenedtly, Philadelphia University,Mozhgan

Bahadory, Shahriar Jahanian, Temple University, USA

Annually, the United States generates 110 million tons of coal combustion ash, of which 65 million tons are fly ash. Only 27% of fly ash produced is reused or recycled, the remaining 73% is landfilled. Alkali Ash Material (AAM) a new and novel material mixed with fine and coarse aggregates producing material with ultimate compressive strength of up to 14,000 psi in one day. AAM is produced at temperatures of 130°F to 210°F.

AAM Concrete is a revolutionary fly ash-based binder developed for precast concrete applications. AAM is based on a unique chemical activation process based on alkali other than calcium- there is no calcium in the system. This causes a remarkable increase in chemical resistance. The AAM system has been used to create concrete materials with excellent corrosion resistant properties. AAM concrete is far more resistant to low pH environment such as, sulfuric, nitric, hydrochloric and organic acids. AAM concrete is also resistant to the effect of freeze and thaw action, based to ASTM C-666 specification. AAM not only possesses desirable physical and chemical properties it also is attractive

economically. Introduction of AAM into construction industry has two fold benefit, first, creation of material with desirable properties, second, utilization of huge amount of fly ash that otherwise would have been landfilled. Near term applications of AAM concrete are: blocks, pipes, median barriers, sound barriers, and overlaying material. Long term applications of AAM concrete are, high strength construction products, such as, bridge beams, prestressed members, concrete tanks, ornamental objects and other concrete products. 18-4

Coal Derived Nano-Materials for Cementitous Material Reinforcement

Elliot B. Kennel, Applied Sciences Inc. Tarunjit S. Butalia, Blaine Lilly, The

Ohio State University, USA

Coal gasification can be used to produce nanoscale carbon structures, which can reinforce cement and concrete and other infrastructure materials. This is possible because gasification conditions can be selected to permit the production of gas with nearly ideal composition for pyrolytic production of carbon nanofibers. Carbon nanofibers are hollow tubes of carbon with an outer diameter of 50-200 nm and a length of about 100 microns. They are produced by introducing an organometallic catalyst to the gas at a temperature of 900-1200 C. In addition, the yield (mass of nanofibers divided by the original amount of carbon present in the reactor inlet feed) can be as high as 30% when sulfur is used as a secondary catalyst. Thus the presence of sulfur in coal gas is an advantage for this process. The economic production of coal-derived nanofibers as well as fly ash can provide an innovative reinforcement strategy for numerous materials, including cement, concrete and other infrastructure materials. The enhancements possible for cementitous materials due to combinations of nanofibers and fly ash reinforcements will be identified by ongoing studies performed at The Ohio State University. Although one of the obvious potential enhancements to be investigated is mechanical reinforcement, it is also suggested that nanofibers may be effective in suppressing microcrack propagation and freeze/thaw cycling-related degradation. Some nanofiber reinforced cementitious materials, such as macro-defect-free cement, can be successfully machined after a few percent nanofiber addition. It is hypothesized that the network created by the nanofibers may limit the propagation of microcracks, so that macroscopic chips are removed during machining operations, rather than larger chunks as is usually the case. Thus nanofiber reinforced macro-defect-free cement may be considered as a low cost, injection moldable, and machinable competitor to ceramics and metals, in addition to the usual role for cement as an infrastructure material.

SESSION 19 COAL GEOSCIENCES & RESOURCES-IV

19-1 Basement Controls on Regional to Minescale Structure and Sedimentation

in the Moranbah Coal Measures: The Super Model 2000 Case Study

J.S. Esterle, G. Le Blanc Smith, J.V.R Yago, R.Sliwa, CSIRO Exploration & Mining, AUSTRALIA

The prediction of geological structures and deleterious ground in advance of mining is critical to cost effective production and mine safety. As a result, the coal industry has moved towards the integration of traditional drilling data with high resolution 2D and 3D seismic, aeromagnetics and ground gravity to produce three dimensional models of coal seam structure and immediate roof and floor lithology for underground mine sites. An emerging outcome is the inter-relationship between seam splitting, interburden sedimentology, in particular the position of geotechnically massive sandstone bodies and weak flanking strata, faulting and poor ground conditions. In areas where drilling is too sparse to accurately resolve small scale or laterally intermittent faulting, the association with more laterally continuous sedimentary domains in the interburden can be used to anticipate and investigate likely ground conditions. Many of these features are larger than individual mine leases and require the synthesis of data from adjacent leases to accurately characterise them and develop models for their prediction. This paper presents a regional model of the Moranbah Coal Measures constructed from high resolution mine scale data sets across 5 adjacent leases covering approximately 500 sq. km of the northwestern limb of the Bowen Basin. This model is the framework from which to examine the relationships between structure, stress and gas that will aid in regional area selection and local hazard recognition and quantification of risk by domains. The results suggest that the local distribution of thick coal seam accumulation, seam splitting, and thick sandstone lithofacies was controlled by subtle

Fig.1. Isopropylation of biphenyl over large-pore zeolites

0

20

40

60

80

100

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structural movements in the basement at the time of deposition. Three laterally continuous coal seams with numerous subordinate seams occur within an approximately 200m thick sequence. Seams vary from <5m to 10m thick and are separated by 10 to 60m of interburden. Seams split and merge along strike, but areas of thick merged seams tend to occur over areas of stable basement domains interpreted from regional gravity. Marginal to these areas, seams split across structural "hinge zones" and are interspersed with thick sandstone bodies. Two sandstone stacking patterns are observed: lateral offset as a function of differential compaction of peat, mud and sand; and vertical stacking as a function of rapid subsidence due to differential movements between basement domains, and also to compaction of very thick peat and mud sequences. Subsequently, the depositional fabric and the basement structure played a major role in partitioning deformation within the coal measures. Domains of consistent normal fault and cleat orientations appear to be bounded by the same structural "hinge zones" that controlled the distribution of thick sandstone bodies. During later deformation, thrust faults tended to deflect around the more competent sandstone bodies. 19-2

Defining Levels of Petrographic Variation in Coal Beds: Examples from

Indonesia and New Zealand

T.A. Moore, CRL Energy Ltd., J.C. Shearer, Canterbury Museum, NEW ZEALAND

Stratified sampling of coal seams for petrographic analysis using block samples is a viable alternative to standard methods of channel sampling and particulate pellet mounts. Although petrographic analysis of particulate pellets is employed widely, it is both time consuming and does not allow variation within sampling units to be assessed - an important measure in any study whether it be for paleoenvironmental reconstruction or in obtaining estimates of industrial attributes. Also, samples taken as intact blocks provide additional information, such as texture and botanical affinity that can not be gained using particulate pellets. Stratified sampling can be employed both on ‘fine’ and ‘coarse’ grained coal units. Fine grained coals are defined as those coal intervals that do not contain vitrain bands greater than approximately 1 mm in thickness (as measured perpendicular to bedding). In fine grained coal seams, a reasonable sized block sample (2.5 cm3) can be taken that encapsulates the macroscopic variability. However, for coarse grained coals (vitrain bands >1 mm) a different system has to be employed in order to accurately account for the larger particles. Macroscopic point counting of vitrain bands can accurately account for those particles >1 mm within a coal interval. This point counting method is conducted using a simple string on a coal face with marked intervals greater than the largest particle expected to be encountered. Comparative analyses of particulate pellets and blocks on the same interval show less than 5% variation between the two sample types when blocks are recalculated to include macroscopic counts of vitrain. Therefore even in coarse–grained coals, stratified sampling can be used effectively and representatively. 19-3

Hydrologic Impacts of Underground Mining of Carboniferous Coals,

Appalachian Basin, USA

SusanTewalt, Eleanora Robbins, Leslie F. Ruppert, Linda J. Bragg, USGS, USA

Digital Geographic Information System (GIS) models of selected coal beds in the northern Appalachian basin coal region,USA have been created by the USGS. Hydrologic issues associated with mining these coals include post-mining flooding of underground mines to form "mine pools" and acid mine drainage. Underground mine pools that are above regional surface drainage can discharge through unplanned catastrophic events ("blowouts") or through continuously discharging locations ("flowouts"). Regional compilation of water discharge points into a GIS coverage that can be related to existing GIS geologic coal models will help evaluate the regional magnitude of these hydrologic issues. 19-4

Studies of the Relationship Between Coal Petrology and Grinding

Properties

Alan S. Trimble, James C. Hower, University of Kentucky, CAER, USA

The maceral and microlithotype composition of selected coals has been investigated with respect to the grinding properties, specifically Hardgrove grindability index, of the coals. The study expands upon previous investigations of HGI and coal petrology by adding the dimension of the amount and

composition of the microlithotypes. Coal samples, both lithotypes and whole channels, were selected from restricted rank ranges based on vitrinite maximum reflectance: 0.75-0.80 %Rmax, 0.85-0.90 %Rmax, and 0.95-1.00 %Rmax. In this manner, the influence of petrographic composition can be isolated from the influence of rank. Previous investigations of high volatile bituminous coals demonstrated that, while rank is an important factor in coal grindability, the amount of liptinite and liptinite-rich microlithotypes is a more influential factor. In this study, we will provide further quantitative evidence for the influence of microlithotypes on HGI and, ultimately, on pulverizer performance. 19-5

Coal Resource Assessment of Top-Producing Coal Beds and Coal Zones in

the Northern and Central Appalachian Basin Coal Regions

Leslie Ruppert, Susan J. Tewalt, Linda J. Bragg, Robert C. Milici, Philip A. Freeman, USGS, USA

The United States Geological Survey, in partnership with the State geological surveys of Pennsylvania, Maryland, Ohio, West Virginia, Kentucky, and Virginia, digitally assessed six top-producing Pennsylvanian coal beds/zones in the northern and central Appalachian Basin coal regions. The Appalachian Basin is one of the most important coal-producing regions in the Nation and the world. Bituminous coal has been mined in the Basin for the last three centuries with cumulative production estimated at 34.5 billion tons (Milici and others, 1999) The six coal beds and zones--the Monongahela Group Pittsburgh coal bed, Allegheny Group Upper Freeport and Lower Kittanning coal beds, and Pottsville Group Fire Clay and Pond Creek coal zones and the Pocahontas No. 3 coal bed--produce over 15 percent of the Nation’s coal (Energy Information Agency, 2000). Preliminary total original resources were calculated for five of the coal beds and zones--the Pittsburgh, Upper Freeport, Fire Clay, Pond Creek, and Pocahontas No. 3-- and are estimated at about 93 billion short tons, of which about 66 billion short tons remain. Much of the remaining coal in all five coal beds and zones is thinner (<3.5 ft) and deeper (>1,000 ft) than the coal that has been mined, but economic resources are still available and mining in each coal bed/zone will continue throughout this decade and into the next given current market conditions. Coal quality issues, especially sulfur content, play an increasingly important role in Appalachian Basin coal production trends. The year 2000 sulfur dioxide emission regulations (U.S. Statutes at Large, 1990), which mandate maximum emissions of 1.2 lbs of sulfur dioxide per million Btu, favor production of coal beds/zones in the central Appalachian Basin coal region over those in the northern Appalachian Basin coal region, because the latter tend to be higher in ash and sulfur than the latter. The Upper Freeport coal bed contains the highest mean ash yield (12.31 wt %, arb) and the Lower Kittanning coal bed contains the highest mean sulfur content (2.90 wt %, arb), whereas the Pocahontas No. 3 coal bed contains the lowest ash yield and sulfur content (5.75 and 0.66 wt %, arb, respectively). In general, mercury contents tend to be higher in northern Appalachian Basin coal beds than in central Appalachian Basin coal beds/zones. The differences in mercury content between the northern and central Appalachian Basin coal regions will become increasingly important if, at the end of 2000, the U.S. Environmental Protection Agency decides that mercury emissions from coal-burning power plants will be regulated. The U.S. is dependent on, and will remain dependant on, coal-powered electric power plants for the majority of our electricity for at least the next few decades. This assessment shows that sufficient coal resources remain in the Appalachians to meet regional electrical generation needs. However, coal quality, and not coal quantity, is expected to be the primary driver for coal production in the Basin. Environmental constraints will continue to drive production from the plentiful, but higher ash and sulfur, northern Appalachian Basin coal to lower ash and sulfur, central Appalachian Basin coal in the next decade.

SESSION 20 GASIFICATION: TECHNOLOGY

ADVANCES-II

20-1

Advanced Gasification-Combustion Technology for Production of H2, Power, and Sequestration-Ready CO2

R. George Rizeq, Vladimir Zamansky, Ravi Kumar, Janice West, GE Energy and Environmental Research Corporation (GE-EER), Kamalendu Das, U.S.

DOE/NETL, USA

GE-EER is developing an innovative fuel-flexible advanced gasification-combustion (AGC) technology for production of hydrogen for fuel cells or combustion turbines, and a separate stream of sequestration-ready CO2. The

23

AGC module can be integrated into a number of Vision 21 power systems. It offers increased energy efficiency relative to conventional gasification and combustion systems and near zero pollution. The R&D on AGC technology is being conducted under a Vision 21 award from U.S. DOE NETL with co-funding from GE-EER, California Energy Commission (CEC) and Southern Illinois University at Carbondale (SIU-C). Work on this three-year program started on October 1, 2000. The AGC technology converts coal and air into three separate streams of pure hydrogen, sequestration-ready CO2 , and high temperature/pressure oxygen depleted air to produce electricity in a gas turbine. The process has theoretical thermal efficiency up to 93% based on the heating value of the fuel. The R&D program is focused on determining the operating conditions that maximize the separation of CO2 and pollutants from the vent gas, while maximizing coal conversion and hydrogen production. Based on results, the economic viability and market potential of the process will be evaluated. The three-year program integrates lab-, bench- and pilot-scale studies to demonstrate the AGC concept. Process and kinetic modeling studies as well as an economic assessment will also be performed. This presentation will provide an overview of the program and its objectives, and will discuss first year activities including design of experimental facilities and results from initial tests and modeling studies. In particular, the presentation will provide initial results form the bench-scale design and shake down task, and from process modeling including a process flow diagram that incorporates the AGC module with other vision-21 plant components with the objective of maximizing H2 production and process efficiency. Since the technology is being designed for fuel flexibility (i.e., using coal and some opportunity fuels), preliminary results from the resource assessment of available low-cost feedstocks will be presented. Preliminary economic estimates will also be shown. 20-2

Zero Emission Coal, A New Approach and Why it is Needed

Hans Ziock, George Guthrie, Los Alamos National Laboratory, Klaus Lackner, Columbia University, John Ruby, Mohammad Nawaz, Nexant, Inc., USA

A new approach to zero emission coal originated at Los Alamos National Laboratory is being pursued by the Zero Emission Coal Alliance (ZECA), an international coalition whose ultimate goal is no atmospheric emissions for coal fueled power and hydrogen production plants. The avoidance of atmospheric emissions by the plant will address carbon dioxide in addition to the more commonly considered coal by-products that include NOX, SOX, particulates, and heavy metals. The new approach combines and updates a number of ideas previously tested at the pilot plant scale in a new, highly integrated design. The integrated approach allows fuel to electric energy conversion efficiencies of approximately 70%, while simultaneously yielding a pure, high pressure CO2 stream, ready for sequestration. For sequestration, ZECA is examining the conversion of the CO2 into mineral carbonates, thereby achieving safe and permanent disposal of the CO2 in an inert solid form. The high efficiency provides for a substantial reduction (~ a factor of 2) in the amount of fuel consumed per unit of power reduced, thereby reducing the amount and cost of by-product disposal by a similar factor. Unlike most other emission reduction processes being investigated that typically offer only marginal and short-term improvements, the ZECA concept is a long-term solution that is fully compatible with the many centuries of clean, low cost, coal based fossil energy available. 20-3

Power Generation from Coal with Zero Atmospheric Emissions

H. Brandt, R., Anderson, V.Viteri, Clean Energy Systems, Inc., USA

Currently and for the foreseeable future, coal provides the major portion of the World's supply of electric energy. Pollution from coal-fired power plants is a pressing environmental problem and the emission of carbon dioxide is becoming a topic of increasing concern in regard to global warming. Clean Energy Systems, Inc. (CES) is developing a technology for the economical production of electricity with zero emissions from virtually any fossil or biomass fuel . This paper describes CES's technology as it applies to the use of coal to produce environmentally clean power. The approach involves the complete or partial gasification of coal. The resulting syngas is cleaned of noxious components and burned with oxygen in the presence of recycled water in a unique gas generator that is based on rocket design features. The combustion directly produces a high-energy drive gas composed almost entirely of steam and carbon dioxide (CO2). These gases drive a multi-stage turbo-generator to produce electricity. The turbine discharge gases pass to a condenser where water is captured as liquid and nearly pure gaseous CO2 is pumped from the system. Because the CO2 is nearly pure, it is very economically conditioned for use in enhanced recovery of oil or coal-bed methane, for other commercial use or for

sequestration. This paper presents CES's design concepts for zero-emissions power plants that are based on complete or partial gasification of coal. These power plants are compared with the most modern integrated coal gasification combined cycle (IGCC) power plants with and without CO2 sequestration capabilities. The comparisons between CES and IGCC power plants include capital costs, operating and maintenance costs, oxygen and coal costs, net efficiencies, net power generation costs/kWh, and emissions. The influence of technology improvements, including oxygen separation by ion transfer membranes (ITM), high-pressure, high-temperature turbines, and advanced CO2 separation on the various power plant cost and performance comparisons are evaluated. These studies indicate that CES systems can potentially achieve net efficiencies in a range above 60% with zero emissions and at power generation costs less than that of a modern IGCC plant without CO2 sequestration. 20-4

Underground Coal Gasification In The United Kingdom

Michael Green, Mark Armitage UCG Programme, Sustainable Energy Policy Unit, Department of Trade and Industry of the UK

The United Kingdom is well placed within Europe in having large reserves of indigenous coal both onshore and offshore in the southern North Sea. These reserves have the potential to provide security of future energy supplies long after oil and natural gas are exhausted. Traditional mining methods however are not suited to working offshore reserves, and development and infrastructure costs of new mines can render the exploitation of landward reserves uneconomical. Underground coal gasification (UCG) has the potential to provide a clean and convenient source of energy from coal seams where traditional mining methods are either impossible or uneconomical. Underground Coal Gasification is a method of converting unworked coal, deep underground, into a combustible gas, which can be used for industrial heating, power generation or the manufacture of hydrogen, synthetic natural gas or other chemicals. The gas can be processed to remove the CO2 before it is passed on to end users, thereby providing a source of clean energy with minimal green house gas emissions. UK Government policy is to encourage the development of cleaner coal technologies for application both at home and in overseas markets. UCG is seen, in the longer term, as a method of reducing environmental emissions and one that offers acceptable levels of diversity of energy supply. The recent UCG trial in Spain, supported by Industry, three European Government Organisations and the EEC, has demonstrated the feasibility of UCG in typical European coal seams. The UK Department of Trade and Industry is now embarked on a UCG study programme with industry, to critically assess the commercial feasibility of UCG. 20-5

Designing for Hydrogen, Electricity, and CO2 recovery from a Shell Gasification Based System

Richard Doctor, John C. Molburg, Norman F. Brockmeier, Argonne National

Laboratory, Gary J. Stiegel, U.S.DOE/NETL, USA

The U.S. Department of Energy (DOE) is investigating CO2 recovery from fossil-fuel cycles as a greenhouse gas mitigation strategy. Recognizing this, we compared two integrated gasification combined-cycle (IGCC) plant designs based on the Shell entrained-flow gasifier. One option, called the “co-product case,” uses high-sulfur Illinois #6 coal to produce electricity and hydrogen (H2) as energy carriers. At the same time, 90% of the carbon dioxide (CO2) is recovered for disposal in geological storage or for use, such as enhanced-oil recovery (EOR). The second option, called the “base case,” is a conventional IGCC power plant releasing CO2 by combustion of the synthesis gas in a gas turbine. Process design has been aided by the use of the ASPEN-Plus© simulation for critical design areas. Special attention is paid to the transport issues for the CO2 product, because transportation technology is a determinant of product specifications, which affect plant design. Separating and purifying the H2 for fuel cell use should yield an impressive gain in overall process efficiency, offsetting the losses in efficiency from recovery and compression of CO2 to supercritical conditions.

24

SESSION 21 FLUIDIZED COAL COMBUSTION-I

21-1 Reactivity of Modified Lime and Limestone for High-Temperature DeSO2

in the Presence of High Concentration CO2,

Shengji Wu, Caili Su, Eiji Sasaoka, Okayama University, JAPAN

Limestone is used as a desulfurization sorbent in pressurized fluidized bed coal combustion. However, the limestone is not stable in the furnace. Part of the limestone will decompose to CaO in the zone in the furnace where the partial pressure of CO2 is low enough for the decomposition of CaCO3. While, other part of the limestone does not decompose in other zone where the partial pressure of CO2 is sufficiently high for prevention of the decomposition of CaCO3. Furthermore CaO produced from CaCO3 in the CO2 lean zone will be reconverted to CaCO3 in the CO2 rich zone. Therefore, it is supposed that SO2 reacts with both CaO and CaCO3 in a PFBC furnace. Many studies on the reactivity of lime and modified lime have been reported, and the relationship between the reactivity for SO2 removal and the property of the lime has been clarified. However, the relationship between the reactivity of CaO and CaCO3 and their properties in the presence of high concentration CO2 has not been clarified. Furthermore, How to modify CaO and CaCO3 for the efficient removal of SO2 has not been clarified. In this study, high-temperature DeSO2 has been investigated using a natural limestone, natural lime, modified limestones and limes. The modified limes were prepared from the natural lime by the water-acetic acid swelling, water swelling and water vapor swelling methods. The modified limestones were prepared from the modified limes by carbonation. It was found that the pore size distributions of the modified limes and limestones depended on the swelling methods. The order of the development of mcropore in the modified limes and limestones by the swelling methods was as followed: water-acetic acid swelling method > water swelling method > water vapor method. The reaction rate of the samples were measured in the system of 1500ppmSO2 - 50(or 10)%CO2 - 5%O2 - 10%H2O - N2, at 800°C using a thermo-balance reactor. It was found that the reactivity of the raw lime was almost same as that of the raw limestone in the presence of 50% CO2, because the raw lime more rapidly reacted with CO2 than with SO2. However, in the case of the modified limes in which macro pores was sufficiently developed, the reactivity was remarkably improved compared with that of the raw lime. Although the carbonation of the CaO predominately occurred compared with the sulfation, the CaCO3 formed by the carbonation was still macroporous and active for SO2 removal. From the obtained results using the modified CaCO3 samples, it was concluded that the pore size distribution of the CaCO3 had a significant influence on the reactivity. Particularly, the pores ranged from 200nm to 1micro meter showed to be important for the SO2 removal. 21-2

Mercury Content of Fly Ash from FBC Systems Co-Firing Municipal Solid

Waste

Shawn Kellie, Kunlei Liu, Ying Gao,Wei-Ping Pan, and John T. Riley, Western Kentucky University, USA

Mercury emissions from coal-fired power plants have been extensively evaluated for nearly ten years to aid in determining possible regulation by EPA. EPA has indicated 51.6 tons of mercury are emitted annually as a result of coal utilization in the utility industry. Considerable effort has gone into developing possible efficient, low-cost technologies for mercury emission reductions from utility plants. The objective of this project was to study the reduction of mercury emission from coal-fired combustors by using HCl provided by high chlorine coals to help convert elemental mercury to oxidized mercury at relatively low temperatures (500-600oC). By oxidizing elemental mercury inside a fluidized bed combustion (FBC) system, total mercury emissions can be reduced with high efficiency and low cost while maintaining low emissions of other pollutants. The results of the study indicate that co-firing municipal solid waste (MSW) in an FBC system converted more than 99% of elemental mercury to an oxidized state, mainly HgCl2. The Ontario Hydro Method was chosen for mercury sampling during all tests. When MSW was used to co-fire with coal, close to 55% of the total mercury input was found in the solid phase (bed and fly ash). Of the mercury found in the solid phase, almost none was found in the bed ash because of its high surrounding temperature (850oC). The gas-phase mercury, which was around 45% of the total mercury input, was determined to be primarily in the oxidized state (40% of the total mercury input), while only a small portion (4.5% of total

mercury input) still existed as elemental mercury in the flue gas even when a MSW/coal ratio was burned without the benefit of secondary air injection. 21-3 High Temperature Bubbling Fluidized Bed (HT-BFB) Combustion Method

for Coal, Refuse and Biomass

Pauli Dernjatin, Fortum Power and Heat Oy, Marko Fabritius, Marika Ryyppö, Jukka Röppänen, Fortum Power and Heat, Ilkka Saarenpää, Tampere University

of Technology, FINLAND

At this moment, there are two main methods for coal combustion: The first one, Pulverized Coal Combustion (PCC), is based on high temperature and low residence time and the other one, Circulating Fluidized Bed Combustion (CFB), is based on low temperature and high residence time. Today there is a growing demand to increase the use of biomass and other kinds on waste fuels like municipal refuse or Refuse Derived Fuels (RDF), because of global warming (CO2). The need to use multi-fuels favors the use of small-size Bubbling Fluidized Bed (BFB) boilers for biofuels or RDF. For co-combustion of coal and biofuel or municipal refuse, bigger size CFB boilers are favored. According to the authors' opinion both methods described above are far from environmentally acceptable as combustion methods in the future, in the point of view of combustion efficiency and UBC content in flyash. This paper presents a totally new combustion technology, based on high temperature and high residence time. Compared to conventinal BFB and CFB boilers the HT-BFB technology has the benefits of lowering NOX and unburned carbon levels, lowering coal milling costs, preventing the formation of dioxins and furans, lowering the risk for high temperature corrosion and increasing the efficiency of SO2 and HCl removal. Small-scale combustion tests and a full-scale demonstration of the HF-BFB technology are also presented in this paper. In the small-scale combustion tests, pulverized coal was combusted in an atmospheric two-dimensional BFB reactor at Tampere University of Technology. In the full-scale tests, pulverized coal (160 MWth) was combusted in a 295 MWth peat fired BFB boiler in Rauhalahti Power Plant in Jyväskylä, Finland. The tests show the coal is ignited rapidly and the flame is stable, when injecting the coal above the bed where peat is burned. When the output of coal is increased, the free board temperature increase and NOx emissions decrease. The unburned carbon content of the fly ash stayed within acceptable levels. The bed temperature, due to the radiation heat of the coal combustion, could be managed. Because of above described benefits of the HT-BFB technology, the authors' believe that this will be a promising method for combusting coal in the future. 21-4

Firing Coal Washing Wastes in a FI CIRCTM Steam Generator Redbank

Power Project of Australia

Gary Goldbach, David Tanner, ALSTOM Power, Samuel D. E. Barber, Redbank Project Pty Limited, USA

The Redbank Project is a 140 MW Fluidized Bed Power Plant located near the Warkworth Coal Mine in the Hunter Valley, New South Wales Australia. The plant started continuous full load operation with high inert content back-up fuel at the end of March 2001. The primary fuel is beneficiated coal washing plant tailings or tailings recovered from existing ponds. The beneficiated dewatered tailing derived fuel (BDTF) system is in its final checkout phase. To date BDTF firing up to 50% of rated fuel flow of a furnace has been demonstrated. Full power generation operation of the plant with BDTF under automatic control is projected to occur in July 2001.

SESSION 22

AIR TOXICS, MERCURY AND PM2.5-I

22-1

Particulate Matter: Trends and Analysis Using Multiple Sampling and Characterization Methods

Thomas Erickson, Steven A. Benson, Jason D. Laumb, Robert R. Jensen, Kurt

E. Eylands, Donald P. McCollor, University of North Dakota, USA

Particulate matter less than 2.5 microns (PM2.5) has received significant attention since the U.S. Environmental Protection Agency (EPA) revised the national ambient air quality standards (NAAQS) in 1997 to include fine particulate matter smaller than 2.5 micrometers. Currently, health impacts of

25

PM2.5 are linked only to mass and not to composition. It is essential that PM2.5 is determined in order to assess health risk and identify sources. The EERC has recently published the results of various sampling methodologies and advanced analytical characterization methods designed to determine the composition and mass of particulate matter. This paper will focus on demonstrating the ability and the necessity of using a suite of sampling techniques and advanced characterization methods to determine the composition of various PM2.5 substances as well as the initial source and eventual health effects. A series of sampling events was conducted in the upper Midwest utilizing a federal reference monitor, an aerodynamic particle sizer (APS), a scanning mobility particle sizer (SMPS), a tapered oscillating microbalance (TEOM) with an automated cartridge collection unit (ACCU), a Burkhard sampler, and a sequential air sampler (SAS). Each of these instruments collects specific information on particulate material with different sampling times and detection methods/collection media, resulting in various biases. Samples from the TEOM with ACCU and Burkhard sampler are subsequently analyzed with a scanning electron microscopy technique for fine particulate and a data analysis system based on cluster analyses and user-defined groups. Isotope analysis of some of the samples is also being performed with an inductively coupled plasma/mass spectrometer (ICP/MS). Samples were taken at three different sites for durations of up to one month in a predominantly agricultural rural region, a rural region with both agriculture and large utilities, and a small upper Midwest city with agriculture and agricultural industries. The data and resultant trends will be presented as a function of location, potential sources, precipitation events, and wind direction and speed. Limited information will also be presented on seasonal variations in PM2.5. 22-2

Performance and Costs of Mercury Reduction Options for Coal-Fired Power Plants

M. Barnes, R. Chang, G. Offen, R. Rhudy, EPRI, USA

For over a decade, EPRI has been assessing options for reducing mercury emissions from power plants, especially via sorbent injection or catalytic oxidation of elemental mercury for subsequent removal in a downstream flue gas desulfurization (FGD) device. Over the past five years, EPRI has developed a cost-effective approach, consisting of on-site fixed-bed characterization and injection testing coupled with modeling studies, to project sorbent requirements and costs for mercury removal at specific utility power plants. This paper summarizes test results from several plants using this approach for commercial activated carbon and several other sorbent types. It also presents oxidation rates, catalyst life, and regeneration capabilities of promising mercury oxidation catalysts that have been evaluated in small-scale reactors for periods up to six months at three utility plants firing bituminous, lignite, and Powder River Basin coals. Finally, the paper will provide cost estimates for mercury removal for each of these processes. The costs for sorbent injection are dominated by the sorbent injection requirements, and these are predicted using a recently refined theoretical model that combines sorbent adsorption characteristics measured under a variety of conditions with mass transfer considerations. Cost estimates are also provided for catalytic oxidation systems, which can be cost-effective at plants that already have an FGD system. 22-3

Fine Particles from Coal Combustion: Formation and Characterisation

B.J.P Buhre, J. Hinkley, R.P. Gupta, T.F. Wall, University of Newcastle,

AUSTRALIA

In recent years, fine particles have been found to be the cause of various harmful effects on health, and many countries have imposed restrictions on emission of these particles. Fine particles (PM 10 and PM 2.5) are formed during coal combustion in power stations and emitted into the atmosphere. Mineral matter in coal is transformed into fine ash particles mainly via three mechanisms: fragmentation of excluded minerals, char fragmentation, and nucleation/condensation of vaporized minerals. At high flame temperatures trace elements evaporate and condense. Rapid cooling of flue gases results in the formation of sub-micron particles from homogeneous condensation, whereas slow cooling would result in heterogeneous condensation on already existing fine particles (PM2.5). The distribution of condensed species is strongly influenced by the cooling rate of the flue gases and the proportion of PM2.5 formed from other two mechanisms. In this study, the formation mechanisms and characteristics of the fine particles have been reviewed briefly. A general model for the formation of fine particles is used to predict the amount of heterogeneous condensation and homogeneous nucleation. The initial surface area for heterogeneous condensation is estimated

from CCSEM analysis of minerals in coal. Finally, the effects of co-firing of biomass and coal blends on the fine particle formation are discussed. 22-4

Ambient Fine Particulate Matter (PM2.5) Sampling and Analysis in the Upper Ohio River Valley (Pennsylvania, USA)

Robinson P. Khosah, Terence J. McManus, Advanced Technology Systems,

Inc., USA This presentation summarizes detailed findings and conclusions drawn from evaluations of data captured to date from the operation of ambient PM2.5 speciation sites in a geographical area encompassing southeastern Ohio, western Pennsylvania and northwestern West Virginia in the United States of America. The overall goal of this program, called the Upper Ohio River Valley Project (UORVP), was to better understand the relationship between coal-based power system emissions and ambient air quality in the Upper Ohio River Valley region through the collection of chemically resolved or speciated data. A summary of the sampling activities, sample analysis and the correlation and interpretation of data acquired from February 1999 through September of 2001 will be presented. PM2.5 data acquired from both discrete filter samplers and continuous emission monitors will be presented and correlated. Mass and speciated data from urban and rural sources will be compared. Also, seasonal variations in PM2.5 distribution will be examined. Finally, preliminary correlations between wind trajectories and total PM2.5 mass will be presented. 22-5

Monitoring, Sampling and Analysis of Fine Particulates at DOE’s National

Energy Technology Laboratory

Richard R. Anderson, Donald V. Martello, Brian R. Strazisar, Curt M. White, U.S. DOE/ NETL, USA

In July 1997, the U.S. Environmental Protection Agency revised the National Ambient Air Quality Standards that set limits on the concentration of ambient air particulate matter with an aerodynamic diameter of 2.5 micrometers or less, (PM2.5). In order to ensure that the new standards have the desired benefit to public health, and to devise a reasonable plan for implementing the standard, more information about the composition of PM2.5 is needed. To accomplish this goal, the National Energy Technology Laboratory has established a fine particulate and gas species sampling station at its Pittsburgh campus located in South Park Township, PA. This sampling station is one of a group of stations scattered throughout Pennsylvania, West Virginia, and Ohio that constitute the Upper Ohio River Valley Project. The sampling station is equipped with a full complement of fine particulate and gaseous monitors. The presentation is a partial summary of results from 24 hour filter weight measurements, continuous gas measurements, and semi-continuous elemental and organic carbon measurements beginning in the autumn of 1999. More detailed analyses were also performed on a limited set of 24 hour filter samples. These analyses included a combination of high-resolution mass spectrometry (HRMS) and gas chromatography-mass spectrometry (GCMS) for semi-volatile organics; computer controlled scanning electron microscopy (CCSEM) with energy dispersive X-ray spectroscopy (EDS) to directly identify the abundence of different particle types such as spherical aluminosilicates (SAS), crustal, carbonaceous, and sulfates; proton induced X-ray emission spectroscopy (PIXE) for bulk elemental analysis; and ion chromatography (IC) for common cations and anions. For the GCMS particle characterization, a Gerstel thermal extractor was used to liberate the semi-volatile organics from the PM2.5 and directly introduce this material into the inlet system of the GCMS instrument. A companion filter was analyzed by HRMS to both confirm and guide the GCMS analysis. The thermal desorption technique avoids material loss and measurement errors introduced by commonly used solvent extraction techniques. The purpose of this study was to identify and measure marker compounds which can be useful in source identification. For the CCSEM / EDS particle characterization, palladium coated polycarbonate membrane filters were used to minimize sample preparation, and to enable unconfounded carbon spectra from carbonaceous particles to be used for direct identification. Other particle classes directly identified from their EDS spectra included spherical alumino-silicates (SAS - a characteristic emission from high temperature coal combustion sources such as pulverized coal fired electric power generation stations), crustal, and sulfate. The relative abundance of these

26

particle types were determined, and the results were compared with other analytical measurements. Changes in the PM2.5 abundance and composition as a function of time were compared with meteorological transport (back trajectory) maps in order to begin to establish general geographic sources.

SESSION 23 GREENHOUSE GAS CONTROL & CO2 SEQUESTRATION-IV

23-1

Economic Screening of Geological Sequestration Options in the United States With a Carbon Management Geographic Information System

Robert T. Dahowski, J. Dooley, D. Brown, A. Stephan, Battelle/Pacific

Northwest National Laboratory, USA

Developing a carbon management strategy is a formidable task for nations as well as individual companies. It is often difficult to understand what options are available, let alone determine which may be optimal. In response to the need for a better understanding of complex carbon management options, Battelle has developed a state-of-the-art Geographic Information System (GIS) with economic screening capability focused on carbon capture and sequestration opportunities in the United States. The GIS contains information (e.g., fuel type, location, vintage, ownership, rated capacity) on all fossil-fired generation capacity in the Untied States and Canada with a rated capacity of at least 100 MW. There are also data on other CO2 sources (i.e., natural domes, gas processing plants, etc.) and associated pipelines currently serving enhanced oil recovery (EOR) projects. Data on current and prospective CO2 EOR projects include location, operator, reservoir and oil characteristics, production, and CO2 source. The system also contains information on priority deep saline aquifers and coal bed methane basins with potential for sequestering CO2. A customized screening mechanism has been incorporated into the GIS to enable prioritization of these geological sequestration options. Levelized costs of CO2 capture, transport, and disposal may be determined for each plant and prospective disposal site. In addition, the value of oil and methane produced from EOR and ECBM processes, along with a value for carbon credits can be included in the analysis. The cost data was developed using best available current information and can be easily updated as more knowledge is gained in this area. It is understood that ultimate costs will vary based on a variety of factors, yet the results provide a comparative indication of the economic viability of CO2 capture and sequestration for each available source and sink. This allows users to make informed decisions regarding the deployment of carbon capture and sequestration systems designed to mitigate carbon dioxide emissions from fossil-fueled power plants. Our paper and presentation will describe the development of this GIS-based economic screening model and demonstrate its use for carbon management analysis. 23-2

Carbon Management Options for Coal-Fired Utility Boiler Systems John Stringer, EPRI, Gillian M. Bond, Margaret M. Medina, New Mexico Tech,

USA

Coal-fired boilers in the United States are responsible for approximately one third of the anthropogenic CO2 emitted. They are however large and stationary sources, and offer perhaps the best option for attempting to reduce the net emissions. The utility industry is exploring approaches that can achieve significant reductions at acceptably low overall costs. In broad terms, there are a number of approaches which are described in EPRI’s Electricity Technology Roadmap: Powering Progress. These include continuing and accelerating the long-term improvements in efficiency of production and use of electricity, and the progressive decarbonization of the fuel. However, if coal is to continue to play a large role in the production of electricity, some method of removal of some fraction of the CO2 from the combustion gas, and its storage in a long-term secure repository (‘sequestration’) would seem to be necessary. There are a number of factors that will determine how much must be removed and sequestered, and the security required of the sequestration option chosen; the details of these will of course be largely determined by the eventual environmental control legislation. The possible associated environmental impacts will also need to be carefully studied. This paper will consider some of these issues for a number of the current options, and in particular will review some of the remaining issues related to the ‘biomimetic’ option that EPRI has been looking at.

23-3

Performance Analysis of Combined Cycles with Chemical Looping Combustion for CO2 Capture

Jens Wolf, Jinyue Yan, Royal Institute of Technology, Marie Anheden,

Vattenfall Utveckling AB, SWEDEN

Chemical Looping Combustion (CLC) is a novel technology for power generation. The main feature of this technology is an inherent separation of carbon dioxide during the combustion. This feature provides a new way of reducing carbon dioxide emission from power plants. An additional benefit is that no nitrogen oxides are expected to be formed during the combustion process. In CLC, instead of the conventional combustion of the fuel with oxygen in the air, the oxidation of fuel is carried out in a flameless two–step reaction in separate reactors. In the first step, the fuel is oxidized in a reduction reactor by an oxygen carrier, which is an oxygen-containing compound, for instance, metal oxide. The energy from the fuel is used to reduce the metal oxide, producing steam and CO2 from the oxidized fuel. After recovering energy from this stream for power generation purposes and condensing the water, the CO2 can be sequestrated with little compression energy. In the second step, the oxygen carrier is re-oxidized by air in an oxidation reactor. This reaction is exothermic and heat is produced for raising the temperature of a high-pressure stream of air or nitrogen to drive a gas turbine to generate electricity. This paper investigates system performance to identify the effects of process design and reactor conditions. Two configurations of the combined cycle with a three-pressure reheat steam cycle as bottoming cycle, have been studied. Both processes include a pressurized CLC with methane as the fuel and iron oxide as the oxygen carrier. In the first configuration, a CO2 turbine is used for recovering the energy from the exhaust from the reduction reactor. In the second configuration, a CO2 turbine is not included, instead the exhaust heat from the reduction reactor is recovered by a bottoming steam cycle. Thermal efficiencies of both processes have been calculated for different temperatures of the reduction reactor. A parameter analysis of the CLC-reactor system has also been carried out by using a new tool for selecting key parameters for the CLC, which is based on energy and mass balance for the CLC-reactor system. A chart is created for mapping reactor parameters, which can predict initial boundaries of the theoretical feasibility for a suitable reactor system. This reveals the relationship between reactor parameters and gas turbine inlet temperature. The reactor parameters include the reduction temperature, the conversion rate during the reduction, the flow rate of the circulating oxygen carrier, the flow rate of the combustion air, and the combustion air temperature. This new design tool is helpful to identify desirable reactor conditions, which are depended upon a selected power generation process. The results from simulations of the CLC power generation systems with and without CO2-turbine have shown that both processes achieve a thermal efficiency over 50%, including the power requirements needed to compress the CO2. This is better than the expected efficiencies of power plants using the more conventional concepts for CO2-separation. 23-4

Full Fuel Cycle Emissions of Greenhouse Gases from Coal Fired Power

Stations

S D Sharma, J A Lapszewicz, G J Duffy, J H Edwards, CSIRO Energy Technology, AUSTRALIA

Coal-fired power station produce around 35% of Australia’s total Greenhouse gas (GHG) emissions. These emissions arise from the various stages of mining, preparation, transportation, utilisation and waste disposal of the fuel. All these stages involve emissions relating to (1) the construction of infrastructure and facilities and (2) operation of the facilities. This paper looks at various scenarios for Australia’s future power generation systems and assesses their impact on GHG emissions. These scenarios include cogeneration and cofiring options, as well as integration with renewable energy systems based on solar, wind or biomass. 23-5

Integration of Coal-Fired Energy Systems with CO2 Sequestration

James Weifu Lee, Oak Ridge National Laboratory, USA, Rongfu Li, Jinhuashi

Chemical Fertilizer Factory, P. R. CHINA

Upon ratification, the recent climate treaty negotiated in Kyoto, Japan, would require the United States and other developed nations to reduce their emissions of greenhouse gases below 1990 levels by the year 2010. Because most

27

anthropogenic greenhouse gas emissions (particularly CO2) come from the use of fossil energy, this agreement has the potential to affect the entire fabric of society. Here, we present a practical and revolutionary method that can sequester greenhouse-gas emissions and at the same time benefit both agriculture and the economy. The proposed strategy utilizes an innovative application of chemical processes to convert CO2, NOx, and SOx emissions into valuable fertilizers [mainly, NH4HCO3 and (NH2)2CO] that can enhance sequestration of CO2 into soil and the earth subsurface, reduce NO3

– contamination of groundwater, and stimulate photosynthetic fixation of CO2 from the atmosphere. This invention integrate pollutant-removing fertilizer production reactions with coal–fired power plants and other energy operations, resulting in a clean energy system that is in harmony with the earth ecosystem. This technology could contribute importantly to global CO2 sequestration and clean air protection. When this technology is in worldwide use because of its high efficiency and carbon credit, in addition to the benefit of clean air protection and stimulation of photosynthetic fixation of CO2 from the atmosphere, maximally 283 million tons of CO2 per year [equivalent to about 5% of the CO2 emissions from coal–fired power plants in the world] from smokestacks can be placed into soil by the use of this technology.

SESSION 24 PYROLYSIS AND DIRECT COAL CONVERSION-I

24-1

Effect of Catalyst and Solvent On Coal Liquefaction

Haoquan Hu, Fei Liu, Jinfeng Bai, Dalian University of Technology, Guohua Chen, The Hong Kong University of Science & Technology, P. R. CHINA

Daliuta subbituminous coal (DL) and Zalainuoer lignite (ZL) were liquefied in a 50ml micro-autoclave apparatus at 350-440, initial hydrogen pressure 5.0MPa, soaking time 30 minutes and tetralin as solvent. The experiments were carried out to investigate the effect of catalyst, included Fe2S3 and ammonium tetrathiomolybdate (ATTM), and solvent, such as mixture of tetralin and cresol or cyclohexane on the conversion and oil yield of liquefaction. The results indicated that with Fe2S3 or ATTM as catalyst the conversion of liquefaction could be enhanced obviously. Without using catalyst, the conversion and oil yield of DL are 49.3 wt % and 43.2 wt %, respectively. At the same condition, with the additive of 1.0 wt % Fe2S3, the conversion, oil yield reach 67.2 wt% and 52.9 wt%, respectively. And with the additive of 1.0 wt % ATTM, the conversion, oil yield are 75.0 wt% and 64.9 wt%, respectively. The effect of solvents on liquefaction indicated that the solvents used could alter the structure of coal macromolecule and enhance the reactivity of liquefaction. Without using solvent, the conversion and oil yield of DL are 40.5% and 37.5%, when tetralin as solvent, the conversion and oil yield are 60.7% and 53.4% respectively; when the mixture of 50% tetralin and 50% cresol as solvent, the conversion and oil yield are 72.5% and 61.0%. 24-2

A Study on the Asphalt Produced By Co-Processing of Coal and Catalytic

Cracking Residue

Yongbing Xue, Zhiyu Wang, Jianli Yang, Zhenyu Liu, Chinese Academy of Sciences, P. R. CHINA

Coprocessing of coal with petroleum resid was considered to be the most economical coal liquefaction rout at the present time. Catalytic cracking resid (CCR), with an annual production of more than 200 million tones in China is difficult to be further processed. In this paper, coprocessing of Yanzhou bituminous coal and three CCRs were studied in a one-liter autoclave to produce paving asphalt. Significant synergetic effects between the coal and the resid were observed. Compared to individual processing, the asphalt yield was enhancing greatly. The rheology of asphalt produced is related to the properties of the resids. The aromticity of the resids was found to be the most influential factor for the synergism and rheology properties, asphalt produced with highly aromatic resid showed good rheology properties, and is possible to be used for highway construction. Composition of asphalt was reported by TLC-FID and NMR.

24-3

Development of Coal Liquefaction Technologies in Japan

Koji Komatsu, Clean Coal Technology Center of NEDO, Yukikazu Miyata, Taku Murakami, Hidemi Sato, Japan Energy Corporation, JAPAN

After the first oil crisis in 1973, Japan initiated research and development in coal liquefaction as a national project under the Sun Shine Program. The goal of this project was to create direct coal liquefaction technologies that would be commercially viable. NEDO has been promoting a series of coal liquefaction projects, from basic research to process demonstration at a pilot plant. The coal liquefaction project has also focused on the development of upgrading technologies on coal liquefied oil to raise the level of its quality. A process development unit (PDU) was constructed to demonstrate the upgrading process. The final products obtained from the PDU are provided for end-use evaluation tests such as engine combustion performance, the capability of blending with petroleum stocks, and storage stability. These tests are some of the most essential in introducing the new fuel into the existing petroleum market. Based on the tests, concepts of a demonstration plant for upgrading were established and a technology package was compiled. 24-4

Role of Water in Hydrogenation of Coal

Yoshiharu Yoneyama, Makoto Okamura, Kanako Morinaga, Noritatsu Tsubaki,

Toyama University, JAPAN

In the coal conversion under hydrogenation conditions with and without catalysts, addition of water increases the coal conversion and the CO2 formation, as well as increases the contents of phenolic compounds in the oils from liquefaction of coals. Thus these results strongly suggest that water itself reacts with coals, irrespective of the presence and the absence of catalysts. In order to clarify the role of water in noncatalytic hydrogenation of coals, several coals including Argonme premium coals were hydrogenated. For comparison we conducted the runs under nitrogen and with n-undecane (n-C11). Because n-C11 has similar critical temperature (366 oC) to water (374 oC) and is a nonpolar solvent, this solvent seems to be suitable as reference. The addition of water promoted the conversions of coals under noncatalytic hydrogenation conditions using both N2 and H2. For example the conversion of Illinois # 6 coal increased from 63.1 to 80.2 % with added water under hydrogenation conditions at 400 oC for 60 min. The conversion of coals using combination of N2 and water increased with increasing carbon contents of coals. However, the conversions of higher rank coals using combination of N2 and n-C11 were lower than those using only N2: retrogressive reactions of coals maybe occur. On the other hand under H2 there was no relationship between the carbon contents of original coals and the conversions of coals using water or n-C11. The conversions of both Illinois #6 and Pittsburgh #8 coals are irregularly large: the coals containing larger amount of pyrite gave higher conversions with added water. Pyrite in coals seems to act as catalysts in coal conversion under H2. In addition, synergistic effects between water and H2 on coal conversions were observed, and being larger for coals containing larger amount of pyrite. These results suggest that pyrite in coals has an important role for synergistic effect between water and H2 on coal conversion . 24-5 Hydrotreated Pyrolysis-Derived Coal Liquids as Candidates for Thermally

Stable Jet Fuels in the Autoxidative and Pyrolytic Regimes

John M. Andrésen, James J. Strohm, Terry L. Keyser, Chunshan Song, Harold H. Schobert, Suchada Butnark, The Pennsylvania State University, USA

Hydrotreating and hydrogenation of tars derived from coal gasification and refined chemical oil (RCO) fraction from coal carbonization can yield naphthenic (cycloalkane-rich) liquids that have jet fuel characteristics. Model compounds of these coal-derived naphthenic jet fuels, such as decalin, have shown superior thermal stability in the pyrolytic regime compared to petroleum derived fuels which are paraffinic based. Since the fuel functions as the main coolant for the different electronic and mechanical parts of the aircraft, thermal stability, especially depression of solid deposition, are key elements in the development of jet fuels for future high-performance aircraft. An additional problem with jet fuels is the presence of dissolved oxygen from air, which reacts with the fuel during the autoxidative regime (150-250°C) before the fuel and its oxygenated reaction products enter the pyrolytic regime (400-500°C). Hydrogenation of highly aromatic petroleum middle distillates has previously been probed as a potential route to avoid a high content of long-chain paraffins and further produced a fuel rich in naphthenes. That approach focused on a light

28

cycle oil (LCO) that was dearomatized by a three step hydrogenation. Although the naphthalene-rich LCO was a good feedstock for obtaining a decalin-rich jet fuel, a considerable amount of long-chain paraffins still remained in the hydrotreated liquid. Accordingly, less alkylated coal pyrolysis-derived liquids were studied to investigate their thermal stability in the autoxidative and pyrolytic regimes. A coal tar derived refined chemical oil (RCO) was hydro-treated under different conditions to generate liquids with varying contents of aromatic, hydroaromatic and naphthenic compounds. Tetralin was the major hydroaromatic compound in the hydrotreated liquids, where the tetralin content ranged from about 1 to 40 wt%. The aromatic compounds were decreasing together with the tetralin content generating an increase in the naphthenic portion. The thermal stability of petroleum-based jet fuels in the pyrolytic regime has been found previously to increase with the addition of hydrogen donors, such as tetralin. However, high aromatic content has been found to promote formation of solid deposits. Accordingly, the present study focuses on the thermally induced chemical reactions taking place in the RCO-derived jet fuels under oxidative and non-oxidative flow conditions and the effect of different compounds on the thermal stability of the jet fuel candidates.

SESSION 25 COAL PRODUCTION AND PREPARATION-I

25-1

Shear Resistant Aggregates for Hydrocyclone Thickening of Fine Coal

Tailings

George V. Franks, Peter Yates, Noel W. A. Lambert, Graeme J. Jameson, CRC for Coal in Sustainable Development, AUSTRALIA

Recent legislation and environmental pressure has made it increasingly important to handle coal tailings in a manner that is both cost effective and of minimal impact to the environment. The use of large tailings ponds to allow for the slow sedimentation of the fine clay particles from dilute suspensions is no longer considered best practice. It is more desirable to thicken (de-water) the tailings prior to disposal and return that water to the coal preparation plant and dispose of a much lower volume of a thickened tailings contains a greater fraction of solids. The use of a hydrocyclone in the thickening of coal tailings could result in several benefits as compared to de-watering in a conventional thickener. The advantages of the hydrocyclone system include lower capital expenditure, smaller footprint, and portability. The use of hydrocyclones for thickening of fine coal tailings has not been put into wide use due to the difficulty in producing clear overflow. The high shear environment within the hydrocyclone is responsible for the break-up of aggregates and the subsequent reporting of the fine particles to the overflow. A method of evaluating the shear resistance of aggregates utilising a shear cell has been developed. The size of the aggregates is measured after shearing at a rate comparable to that believed to be found within a typical hydrocyclone. Coal tailings from the Hunter Valley, NSW Australia with an average size of about 0.4 microns were investigated. The size of aggregates after shearing was measured for a range of different polymeric flocculants of varying molecular weight and charge density. Under certain conditions 90% of the aggregates have size greater than 45 microns after shear at 1200/sec. for 30 seconds. Calculations based on the results suggest that under these aggregation conditions less than 5% of the feed solids will report to the overflow. Currently experiments utilising a hydrocyclone are being conducted to confirm the predictions from the shear cell experiments. 25-2

Modelling Fragmentation from Pit to Plant Feed

J. S. Esterle,CSIRO Exploration & Mining, D. Thornton, Frank Shi, Alan

Cocker, Julius Kruttschnitt Minerals Research Centre, AUSTRALIA

The size distribution and composition of feed to any coal preparation or utilisation process will impact on the desired product. Techniques have been developed that integrate inherent textural and material properties of the coal into comminution models. The outcome is the capability to simulate the fragmentation chain from pit face, through mining, handling and processing to mill feed and product.

25-3

Compton Profile Analysis-A Novel Gamma-Ray Technique for the On-Belt Analysis of Coal

J. R. Tickner, G. Roach, CSIRO, AUSTRALIA

A novel gamma-ray method for the determination of ash in coal has been developed which demonstrates considerable advantages over conventional on-belt analysis techniques. The dual energy transmission (DUET) method is widely used in industry but has difficulty with variations in ash composition and typically requires re-calibrating for different coal seams. X-ray fluorescence (XRF) systems, whilst potentially insensitive to variations in ash composition, can only measure a thin surface layer and typically require sampling of the coal stream. The proposed new technique, termed Compton profile analysis (CPA), relies on measuring the energy spectrum of gamma-ray photons that have been inelastically or Compton scattered from the coal under study. The shape of this spectrum carries information about the distribution of the energies of atomic electrons in the sample, which in turn can be used to infer the ash content of the coal. The method offers good discrimination between light elements (H, C and O) and heavy elements (Al, Si, Ca and Fe), but is relatively insensitive to which of the heavy elements are present. For example, the method is a factor of 7.1 less sensitive to iron variations in the ash compared to the DUET technique. Consequently, the method is ideally suited to the measurement of ash in coal with varying ash composition. A series of 50 synthetic coal samples has been prepared with ash contents in the range 5-15% and widely varying ash compositions. The C, H and O ratios were also varied to simulate coals with different moisture levels and organic compositions. Scattered gamma-ray spectra were collected using a low energy 241Am source and a high-resolution detector. For these samples, the RMS error for ash determination was found to be 0.58 wt% for a 20-minute measurement time. Inclusion of information on coal moisture (for example, from an on-belt moisture analyser) and the use of faster detection electronics is expected to reduce this error to below 0.4 wt%. For comparison, the theoretical DUET error for these samples was calculated to be 1.4 wt%. It is anticipated that the recent commercial availability of low-cost, room temperature, high-resolution gamma-ray detectors should enable a CPA gauge to be produced at similar cost to a conventional DUET instrument. A new round of experimental measurements using real coal samples and an optimised analyser design is proposed. 25-4

Assessment of the Effectiveness of Inert Cover Layers to Control the Heating of Spoil-Piles in Open Cut Coal Mines

A. Saghafi, J N Carras, CSIRO Division of Energy Technology, C Roberts,

ACIRL Pty Ltd, AUSTRALIA There are a number of methods for the control of self-heating in spoil piles from open cut coal mines. A common approach is to use cover layers, which entail covering the contoured and compacted spoil with a layer of inert materials. As the purpose of the cover layer is to exclude oxygen from the spoil pile, the voidage, permeability and thickness of the cover layer will have significant impacts on the efficiency of this method. Liquid water, which can serve to occlude air voidage within the cover layer, can significantly reduce the diffusion coefficient of oxygen through the cover layer and hence flux of oxygen. Thus an understanding of the transport and fate of water is crucial in determining the effectiveness of the layer. In order to provide design guidelines for cover layers the numerical model of heat and mass transfer developed for coal spoil piles, SPLGOF, was applied to this issue. The model, which is based on the conservation equations for heat, oxygen and water, was validated against known analytical solutions of coupled heat and mass transfer in porous media. The liquid water distribution in the system was calculated by coupling SPLGOF to a standard water flow model developed for predicting water flow in soils. This paper presents and discusses a number of scenarios in the use of cover layers to control self heating.

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25-5

Biological-Chemical Methods in the Desulphurization Processes in the Energy Production Technologies from Fossil Fuels

Mária Kušnierová, Helena Vašková, Ústav geotechniky SAV, Peter Fečko,

Adriana Farkašová, VŠB-Technical University, Czech Republic

For the processes of biological-chemical sulphur extraction that is qualitative limiting constituent of energetic coal were applied bacterial cultures of Thiobacillus ferrooxidans, Thiobacillus thiooxidans and their mixture directly in the leaching media. Bacteria Thiobacillus ferroxidans were used for the preparation of bacterial film Bacfox for the indirect application in leaching process because of purpose biological regeneration of leaching reagent on the base of ferric sulfate ( generally used in sulphur extraction from coal). The obtained results confirmed highest extraction efficiency of sulphur (86%) in the biological-chemical leaching with mixed bacterial culture applied. Experiments of biological regeneration of chemical leaching reagent approved the same efficiency of chemical sulphur extraction from coal when more than once regenerated reagent (on the base ferric sulfate) was applied.

SESSION 26

GASIFICATION: FUNDAMENTALS-I

26-1

Full Scale Sasol-Lurgi Fixed Bed Test Gasifier Project: Impact Of Particle Size Distribution, Destoning And Gasifier Operating Conditions On

Sulphur Production

MJ Keyser, Sasol Technology, JC van Dyk, RLC Coetzer, NJ Wagner, Sasol Technology, SOUTH AFRICA

The experimental design and some of the results obtained during Sasol’s full scale Sasol/Lurgi fixed bed test gasifier project, were presented at the Seventeenth Annual International Pittsburgh Coal Conference held from 11-14 September 2000 in Pittsburgh, USA. The first phase of the test program was successfully completed during the period September 1998 to March 2000, and the process to interpret and fully understand the results obtained are still under way. Recently the effect of coal particle size distribution, destoning by dense medium separation, and gasifier operating conditions on sulphur production was statistically evaluated and quantified. The results are supported by laboratory coal washing experiments, as well as by petrographic analyses on coal samples. From the statistical evaluation conducted on the sulphur data from the test gasifier, it was established that the sulphur production is not a function of gasifier operating conditions (e.g. throughput), but only of the coal particle size distribution and the ash content. The sulphur concentration in the raw gas was found to be proportional to the square of the ash content, and not linearly. For the current particle size distribution, destoning at a relative density (RD) of 1,95 reduces the sulphur concentration in the raw gas by approximately 32%. The particle size distribution affects sulphur production, and the maximum reduction in sulphur production was obtained with the finest size distribution followed by destoning. The least reduction in sulphur production for destoned coal was obtained with the coarsest size distribution (average reduction of 22%). Without destoning, the sulphur production is increased by approximately 10% from current levels if the fine end of the size distribution (< 8mm) is removed, and destoning of these size distributions are required for a reduction in sulphur production from current levels. The inorganic material (i.e. sink fraction at RD = 1,95) was sampled during the test gasifier runs and characterised. Each composite sample was visually sorted by a geologist in the groups containing roof, floor, C-shale, pyrite, carbonates and siltstone material. Average mineral matter distribution (mass %) of the South African coal tested is: Carbonates (6%), C-shale (19%), Pyrite (12%), Roof (18%), Floor (46%) and Siltstone (22%). Each of these minerals were characterised by XRD. Based on a petrographic evaluation, most of the pyrite occurs in a finely dispersed sub-micron form bound within the organic matrix. Theoretical calculations based on petrographic images showed that the pyrite can be decreased by approximately 20% with washing, which is in fair agreement with the ±30% reduction in sulphur production discussed above. Petrographic analyses on coal samples indicated four dominant modes of pyrite, i.e. intrusive dendritic pyrite, large pyrite nodules bound with quartz and coal, framboidal / smaller nodular pyrite and finely distributed pyrite flecks.

26-2

Advanced High-Temperature, High-Pressure Transport Reactor Gasification

Michael L. Swanson, Douglas R. Hajicek, Ann K. Henderson, University of

North Dakota, USA

The U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Office of Power Systems Product Management has as its mission to foster the development and deployment of advanced, clean, and affordable fossil-based (coal) power systems. These advanced power systems include the development and demonstration of gasification-based advanced power systems which are an integral part of the Vision 21 program being developed by DOE for the coproduction of power and chemicals. DOE has also been developing advanced gasification systems that lower the capital and operating costs of producing syngas for electricity and chemicals production. A transport reactor has shown potential to be a low-cost syngas producer compared to other gasification systems since its high throughput reduces capital costs. This work directly supports the Power Systems Development Facility (PSDF) utilizing the Kellogg, Brown and Root (KBR) transport reactor located at the Southern Company Services (SCS) Wilsonville, Alabama site. Over 2000 hours of operation on nine different coals ranging from bituminous coal to lignite along with a petroleum coke have been completed to date in the pilot-scale transport reactor development unit (TRDU) at the Energy and Environmental Research Center (EERC). The EERC has established an extensive database on the operation of these various fuels in both air-blown and oxygen-blown modes utilizing a pilot-scale transport reactor gasifier. This database has been useful in determining the effectiveness of design changes on a transport reactor gasifier. It has been demonstrated that corrected fuel gas heating values ranging from 105 to 130 Btu/scf can be achieved in air-blown mode. Factors that affect the TRDU product gas quality appear to be circulation rate, coal type, temperature, and air:coal and steam:coal ratios. The TRDU has recently been modified by increasing the transport reactor mixing zone length and replacing the J-leg loop seal with an L-valve loop seal. These modifications were undertaken to increase solids circulation rates and solids density in the mixing zone to provide adequate carbon in the bottom of the mixing zone while in oxygen blown mode. These modifications also increase solid backmixing in the mixing zone, thereby increasing solids residence time and gasifier performance. The effects of different fuel types on both gasifier performance and the operation of the hot-gas filter system have been determined. Operating results from the enriched-air and oxygen-blown operation will be utilized to optimize future tests at the PSDF and to make commercial projections about the performance of an oxygen-blown transport reactor in a Vision 21 plant. 26-3

Gasification of Brown Coal for Power Generation

T R Johnson, E N Mouritz, HRL Limited, AUSTRALIA

Low rank coals (lignites and brown coals) form a substantial part of world coal resources with significant utilisation for power generation in many countries. Typically these younger coals have high moisture content, low calorific value and in many cases difficult ash characteristics. They are not readily transported so constitute an energy source that has good price stability set by the long run cost of open cut mining. However, the technology needed for their use has been more complex and costly than for black coals, and their carbon intensity of the power generation is also higher. Thus future use of low-rank coals is being questioned in some places. New technological solutions are needed to overcome these problems or their power generation role will come under threat. Gasification combined-cycle is one approach and low rank coals offer some advantages over black coals in using this technology. They are highly reactive which means that high gasification rates can be obtained at moderate temperatures. This allows the use of low temperature fluidised bed gasification using air as the gasifying agent, but this technology is limited to coals that produce ash with moderately high sintering temperature. A major requirement for low-rank coal use is cost-effective drying as the coal is to wet to be burned or gasified in its as-mined state. A number of drying technologies have been tried, but most of these are too costly and have made IGCC power generation from low-rank coals uncompetitive. Integrated drying overcomes the cost barrier to IGCC. The integrated drying gasification combined cycle process (IDGCC), developed specifically for the high moisture coals of the Latrobe Valley in Victoria, Australia, is highly competitive with alternative power generation options in that region. The

30

development program, started by the former State Electricity Commission of Victoria 10 years ago and continued by HRL Limited, has demonstrated the technology at the 10 MW-scale. The technology is ready for commercialisation at 125 MW-scale, the most prospective option being a “piggy-back” development on an existing power station site. 26-4

Gasification of New Zealand Coals

A. H. Clemens, D. Gong, T W Matheson, CRL Energy Limited, NEW

ZEALAND

Coal chars derived from New Zealand lignites are found to be extremely reactive under the low temperature conditions associated with fluidised bed gasification. They typically react around 1.5 times more rapidly than brown coals known to be of sufficient reactivity for use in fluidised bed gasification. A char sample derived from a commonly used sub-bituminous rank coal was of similar reactivity to the brown coals. Much of the high reactivity was found to be due to catalysis by naturally occurring calcium although only that bound to organic sites within the coal was catalytically active. Above a certain threshold level even these types brought about little change in consumption rate although, under certain conditions related to gasifier geometry, they were able to bring about a continuous change in product gas composition such that the products were almost wholly composed of hydrogen and carbon dioxide. The reasons for these findings were identified and are discussed. So too are the implications of the findings for utilisation of the coal. 26-5

Volatile Release and Reactivity Characteristics of 13 Australian Reference

Coals at Elevated Temperatures and Pressures

M. D. Kelly, D. J. Harris, D. G. Roberts, C. J. Mill, CSIRO Division of Energy Technology, AUSTRALIA

It is important to be able to effectively determine volatile yields (VY) and gasification reactivities for coals used in practical gasification. As pressure has a strong influence on the pyrolysis processes and on the rates of char gasification reactions, it is necessary to determine these factors at pressures relevant to the systems of interest. In this paper, two laboratory bench-scale techniques have been used to produce this data. Coal volatile yields were measured under high heating rate and high-pressure conditions in a wire-mesh reactor (WMR); and char reactivity parameters were measured at elevated pressures in a pressurised thermogravimetric analyser (TGA). This paper provides practical VY and intrinsic rate data on 13 Australian coals. The WMR results demonstrate that lower rank coals can produce significantly higher volatile yields than predicted by the standard proximate volatile matter analysis and, conversely, some high rank bituminous coals and semi-anthracites can produce VY’s significantly lower than that indicated predicted by standard analysis. Char structure was also shown to be profoundly affected by the pyrolysis pressure. Char reactivity measurements on the 13 chars produced in the WMR were performed using TGA analysis in three different gases: CO2, H2O and O2. These measurements provide apparent and intrinsic rate data as a function of conversion. The effects of reactant gas and coal type on the char gasification rate and the use of these techniques as a rapid, inexpensive coal gasification assessment tool will be discussed in the paper.

SESSION 27

FLUIDIZED COAL COMBUSTION-II 27-1

Ash Problems in Fluidised-Bed Combustors: Prevention and Control

H.B. Vuthaluru, D.K. Zhang, Curtin University of Technology, AUSTRALIA

One of the most promising energy conversion technologies for solid fuels is fluidised-bed systems for combsution (FBC) or gasification (FBG) which offer greater efficiency, fuel flexibility and environmental benefits. Due to the relatively low operating temperatures, sulphur emissions and extent of deposit formation can also be kept to a minimum when firing lignites, biomass, municipal solid waste and other low grade fuels. However, bed agglomeration could be a potential problem which can decrease both the heat transfer in the bed and fluidisation quality, resulting in poor conversion efficiencies and in extreme

case, leading to defluidisation of the bed. The paper reviews control methods investigated to date for mitigating particle agglomeration and bed defluidisation during fluidised-bed combustion of low-rank coals. The effectiveness of several control methods including, the use of alternative bed materials, mineral additives, pretreatment of coal and coal blending will be discussed. Mechanisms associated with several of these control methods to prevent ash-related problems in fluidised bed combustors will also be addressed. Discussions will also address relevance of the knowledge base obtained with lignites to wider applications including black coal fired fluidised-bed combustion systems. 27-2

Influences of Coal Macerals on Unburned Carbon Elutriation in

Pressurized Fluidized Bed Combustion

Alan L.T. Wang, John F. Stubington, CRC for Coal in Sustainable Development, AUSTRALIA

Unburned carbon elutriation predominantly determines the coal combustion efficiency in PFBC and may contribute to the problem of ‘sticky ash’ in the hot gas clean-up filters. The carbon elutriation behaviour from PFBC of a wide range of Australian black coals and international coals were measured under the industrial PFBC conditions (1.6MPa, 850oC, and 0.9m/s fluidizing gas velocity) in the novel designed bench-scale PFBC facility built at UNSW. In-bed char samples generated in the PFBC combustor were collected and characterized. The influences of coal petrography on coal char properties and unburned carbon elutriation in PFBC were studied. Carbon elutriation from PFBC varied significantly with coal type. The significant effects of macerals on PFBC char properties and the carbon elutriation from PFBC were identified. Telovitrinite, a sub-group of vitrinite, was the primary maceral component affecting coal and char properties and correlated with carbon elutriation from PFBC during coal burnout. Higher telovitrinite content gave the coal greater swelling behaviour and led to the formation of larger pores or higher porosity in the char particles during devolatilization in PFBC. The greater swelling provided more external particle surface area for attrition and the higher porosity and larger pores resulted in a higher specific attrition rate, and then led to higher unburned carbon elutriation from PFBC. 27-3

Influences of Fly Ash Characteristics on the Pressure Drop at Ceramic

Tube Filter in PFBC Operation

K. Iwamoto, F. Ishom, Y. Korai, I. Mochida, Kyushu University Kasuga, H. Sasatsu, N. Misawa, Electric Power Development CO., LTD, T. Harada,

Nishinippon Environmental Energy Co, LTD, JAPAN

Wakamatsu EPDC 71MW PFBC demonstration plant has been successfully operated using ceramic tube filter (CTF) for exhaust gas cleaning before gas turbine generation. Back wash of CTF at adequate interval succeeded to fain the pressure drop level acceptable for long term operation. Nevertheless the pressure drop level was subjective to the coal for combustion. A coal was found the pressure drop level of 30kPa at CTF while the coal increase to 38kPa. The latter coal left very fine fly ash within the pore of the filter, to induce which was recovered after the shot down. The ash was found to consist principally of fine quartz powders. Such very fine ash causes the high pressure drop by staying aroud the filter at back wash. The fly ash recovered from the surface of the filter consisted of mixtures of large and fine powders, many of fine ash adhering on the large ash powder.

Hence, the fine fly ash which is their molly stable appears very influential on the pressure drop at the ceramic tube filter. It is important to control such fine ash for the long term operations. 27-4

Hot Gas Desulfurization Sorbents for Fluidized-Bed Applications

Chong Kul Ryu, Joong Beom Lee, Dal Hong Ahn, Jong Jin Kim, Korea Electric

Power Research Institute, KOREA

In sorbent development of hot gas desulfurization applicable to the fluidized-bed and/or the transport reactor, sorbents must have a uniform morphology(sphere and dense), size and size distribution(100 and 40-250, respectively), and fast and high sorption capacity of H2S as well as low temperature light-off and smooth regeneration. Sorbent also withstands in the fast solid circulation process without much loss of attrition. Therefore the key issue in sorbent development is the sorbents' ability to retain their reactivity and physical integrity during repeated sulfidation and regeneration cycles in fast sorbent circulating processes

31

under harsh conditions(20-30 bar and 450-550 in reduced and oxidized atmosphere). The spray-dried, ZnO-based sorbent (e.g. ZAC-9N) developed at the early stage (1997-9) turned out to be rather soft, especially after 10 cycles and the sulfur sorption capacity dropped to 50 % of its original capacity after a few cycles with 1 fluidized-bed reactor. The modified ZAC-9N sorbent of 60 kg (AI = 60%), which was supplied to the Korea Institute of Energy Research (KIER) for the desulfurization process development, showed the improved reactivity (no sign of the sorption capacity drop) and attrition resistance during the tests in the 3 fluidized-bed reactor but still showed poor attrition resistance (AI = 80%) for used sorbent measured by a 3-hole air-jet attrition tester (ASTM D 5757, 10slpm). To further improve the performance of ZnO-based sorbents, the binder matrices were screened to multi-component systems. Some of the formulations showed high attrition resistance (AI = 8-30% at 10 slpm) which are comparable to or better than those of the commercial FCC. Such high attrition resistant sorbents also showed reasonable H2S sorption capacities (H2S > 10 wt%). 27-5

Development of a New Brown Coal Fired Combined-Cycle Power Plant

Using CPFBC, 2nd Generation

Hans J. Krautz, F. Schierack, Brandenburgische Technische Universität Cottbus (BTU), GERMANY

In addition to developing and building conventional brown coal power plants using optimized plant technology, the German energy utilities and universities are investigating and assessing combined-cycle power plant concepts which, over the long term, might compete with conventional steam facilities. In this context, the concept of a combined-cycle power plant with circulating pressurized fluidized-bed combustion was investigated at different sizes. The theoretical investigations were complemented by experiments on a variety of experimental systems at laboratory and bench scales. It was necessary to conduct experimental tests because no experience-based knowledge was available on pressurized fluidized-bed combustion of brown coal. The paper will describe the following results of the experimental tests: -feeding of brown coal with a high water content into pressurized chambers -emissions and combustion behavior of brown coal in pressurized fluidized-bed combustion systems -product gas quality during substoichiometric combustion. These results were used to define the design parameters of a potential demonstration plant which was discussed. Since mid-1998, a new experimental program has been in progress at Cottbus University to develop a power plant concept as a further step to a second-generation circulating pressurized fluidized bed. The research program focuses on experimental investigations using a laboratory-scale facility, aimed at defining the process engineering parameters for the development of a power plant concept. The goal is to allow brown coal-fired power plant technologies access to the efficiency range above 50 %.

SESSION 28

AIR TOXICS, MERCURY AND PM2.5-II

28-1

Membrane-Based Wet Electrostatic Precipitation

David J. Bayless, Hajrudin Pasic, M. Khairul Alam, Roger Radcliff, Ohio University, John Caine, Southern Environmental Corporation, USA

Emission of fine particulate matter, PM2.5, in both primary and secondary form, is difficult to capture in typical dry electrostatic precipitators. Sulfur or nitrogen acid gases (secondary PM2.5) are virtually impossible to collect in dry precipitators. Fine particulates (primary PM2.5), especially those in the sub-micron sizes, are difficult to collect in dry precipitators due to reasons varying from low corona power caused by ash layer resistivity to re-entrainment. Wet (or water-based) electrostatic precipitators are well suited for collection of acid aerosols and fine particulates due to greater corona power and virtually no re-entrainment. However, field disruptions due to spraying (misting) of water, formation of dry spots (channeling) due to the effects of water surface tension, and collector surface corrosion limit applicability of current wet precipitators in the control of secondary PM2.5. Researchers at Ohio University have patented novel membrane collection surfaces to address these problems. Water-based cleaning in membrane collectors made of corrosion resistant fibers is facilitated

by capillary action between the fibers, maintaining an even distribution of water. This paper presents collection efficiency results of lab-scale testing at Ohio University and pilot-scale testing at Southern Environmental Inc. for membrane-based wet electrostatic precipitators. The results indicate that novel woven membrane collecting surfaces collect particles at efficiencies greater than predicted by the Deutsch-Anderson equation, as well as maintain even wetting and high corona power. Capture efficiencies are shown to far surpass those of steel plates. 28-2

Vapor Phase Mercury Removal by Virgin and Sulfurized Activated

Carbons

Si Hyun Lee, Sun Young Cha, Sang Il Choi, Young Ok Park, Korea Institute of Energy Research, S. KOREA

Mercury has been identified as a health and environmental hazardous material. Activated carbon adsorption offers promising potential for the control of mercury emissions from sources(CFPPs and MWCs). In this research, vapor phase mercury adsorption by virgin and sulfur impregnated activated carbons were investigated. Factors affecting the adsorption capacity of virgin and sulfurized activated carbons such as pore characteristics, functional groups and sulfur impregnation conditions were investigated. Comparisons of adsorption characteristics with commercial virgin and sulfurized carbons were made. It was found that the sulfur allotropes play a critical role in adsorption of mercury vapor by sulfurized activated carbons. Effect of sulfur impregnation temperature on the mercury removal efficiency of sulfurized activated carbons was considered. Adsorbed states of sulfur molecules affecting on the mercury removal capacity were also discussed. 28-3

Capture Characteristics of Trace Metal Compounds by Sorbents in Various

Atmospheres

Hong Yao, Iddi S.N. Mkilaha, Ichiro Naruse, Toyohashi University of Technology, JAPAN

Fundamentals on emission control of trace metal compounds of lead, cadmium and chromium in combustion processes were experimentally studied, using a thermobalance, at relatively low temperature ranged from 1073 to 1273K and in various atmospheres such as air, simulated exhaust gas and reducing gas. Seven types of sorbent such as alumina, silica, kaolinite, limestone, wasted seashell, natural zeolite and apatite were tested as samples. The effect of HCl in the simulated exhaust gas on the capture efficiency was also tested. In the air and simulated exhaust gas natural aluminosilicates of kaolinite and zeolite were found to be effective sorbents to chemically capture the trace metal compounds. The calcium-based sorbents of limestone, wasted seashell and apatite could capture both trace metals and chlorine. Both alumina and silica have low activity to capture the trace metals. The pore structure inside the sorbent might affect the capture activity. However, most of chlorides were easily evaporated at relatively low temperature and in any atmospheres, even if the sorbent were added, since melting temperature of those chlorides is relatively low. In the reducing atmosphere, on the other hand, the capture activities for all of the sorbents decreased partly. This is because the by-products might be reduced. Especially, all of Cd compounds evaporated even in the existence of the sorbents. Besides, in the presence of HCl the capture efficiency decreased sharply since the trace metals react with Cl and the chlorides were produced. 28-4

Modeling Suppression of Dioxin Formation During Coal Combustion

B.K. Gullett, M.A. Telfer, U.S. Environmental Protection Agency, National

Risk Management, USA

Polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are trace, toxic combustion byproducts that are chemically stable in postcombustion environments. Consequently, it is more desirable to prevent their formation than to impose control or destruction technologies. Research over the last 15 years has refined the possible formation pathways of PCDDs/Fs to (i) low-temperature (250-350oC) reactions involving fly ash carbon and organic or inorganic chlorine in the fly ash (i.e., “de novo” synthesis), ii) heterogeneous, catalytic reactions with the fly ash surface and gas-phase precursors such as chlorinated phenols (ClPhs) and chlorinated benzenes (ClBzs), and iii) high-temperature (> 500oC), homogeneous, gas-phase reactions of precursor compounds. PCDDs/Fs are not emitted from the combustion of coal in modern boilers, despite sufficient fuel borne chlorine (Cl) and metal catalysts as well as the

32

potential for trace aromatic emissions. Similarly, cofiring of high sulfur (S) coal with municipal waste (MW) has demonstrated significant suppression of PCDD/F emissions from normal waste firing and allows insight into the understanding of the formation mechanisms. Investigations of this preventive effect have particularly focused on the role of increased S concentrations during coal cofiring and the interactions between S and one of the main PCDD/F constituents, Cl. A mechanistic understanding of whether S inhibits gas-phase Cl reactivity and the formation of chlorinated organic precursor compounds or inhibits the inorganic Cl reactivity in the fly ash will help to elucidate the predominant PCDD/F formation pathways and develop preventive measures. Sulfur has been postulated to deplete the concentration of reactive chlorine gas (Cl2) by the reaction: Cl2 + SO2 + H2O = 2HCl + SO3 (1) and suppress the Deacon reaction: 2HCl + 1/2O2 = H2O +Cl2 (2) through conversion of the catalyst to the less active copper sulfate (CuSO4). Determining whether S affects PCDD/F formation via a gas-phase route is confounded by the problem that there have not been many conclusive studies of the reactive form of the Cl, or its concentration effect on PCDD/F emissions. More recently, chemical kinetic modeling of C1-C2 chlorocombustion systems have revealed that reactive Cl radicals are persistent in postcombustion zones at temperatures as low as 700oC. Bench-scale combustion experiments have validated this and even demonstrated their potential to rapidly chlorinate aromatic compounds (benzene) at temperatures between 500 and 900oC. This suggests that these active Cl radicals (Cl•) may be responsible for aromatic chlorination and PCDD/F formation. Sulfur dioxide (SO2) is an active radical recombining agent (scavenger) and can easily react with Cl• to inhibit further chlorination reactions. Hence, detailed studies of Cl speciation coupled with aromatic formation/chlorination and interactions with S would help us understand the formation of PCDD/Fs and optimization of PCDD/F suppression via cofired combustion of MW and high-S coal. In this work, homogeneous gas-phase modeling of a simplified combustion system [Cl2 injected into a methane (CH4) flame) was developed to understand the gas-phase formation of PCDDs/Fs and possible suppression by SO2. Chemkin v3.6 was employed as a driver to run the model simulations incorporating a well-stirred reactor (Aurora) in series with a plug-flow reactor (Senkin). A validated C1-C2 chlorocombustion mechanism was extended with C2-C6 combustion reactions, C2+C4 benzene formation reactions and C3H3 and C3Clx coupling reactions to form benzene and chlorinated benzenes, respectively. A benzene combustion submechanism was tested against experimental data and also incorporated into the model along with chlorination reactions to predict the formation of ClPhs. Optimum temperature and time conditions for ClPh and ClBz formation in the postcombustion zone were investigated. Applicable SO2-Cl2 gas-phase combustion reactions were incorporated into the mechanism to study gas-phase S inhibition of PCDDs/Fs. 28-5

An Investigation of Mercury Emission from Fludized Bed Combustion

Systems, Fired Different Fuels

John Riley, Kenlei Liu, Wei-Ping Pan, Shawn Kellie, Western Kentucky University, USA

Mercury is widely used in industry because of its diverse properties, which make it an important part of many industrial processes and an important ingredient in many products. However, concern over health issues has led to a 75% decline in the industrial demand for mercury over the past 11 years. The objective of this study was the reduction of mercury emissions from coal-fired combustors by using HCl provided by the coals to help convert elemental mercury to oxidized mercury. By oxidizing elemental mercury inside a fluidized bed combustion (FBC) system, total mercury emissions can be reduced with high efficiency. However, there are a number of interactions and trade-offs between the emissions of mercury, SO2, CO, and HCl and the operating conditions of Flue Gas Desulfurization (FGD) systems. In this study four kinds of coal were burned in an 0.1 MWth FBC system at WKU to investigate the effect of combustion temperature, chlorine and sulfur contents in the coals, and addition of limestone on mercury emission. Further investigation was done to see if the HCl produced during combustion could help convert elemental mercury to oxidized mercury when cofiring coal with municipal solid waste. Five different concentrations of municipal solid waste and coal were burned in WKU=s 0.1 MWth FBC system. The results of the study indicate that using high-chlorine coal in an FBC system converted more than 99% of elemental mercury to an oxidized state, mainly HgCl2. This form of mercury is easily captured by fly ash and in electrostatic precipitators.

SESSION 29 GREENHOUSE GAS CONTROL & CO2 SEQUESTRATION-V

29-1

Technologies for Reducing Greenhouse Gas Emissions from Coal-Fired Power Generation

P. Freund, UK, R. A. Durie, CSIRO Energy Technology, P. McMullan,

Electricity Supply Association of Australia, AUSTRALIA

The emissions of greenhouse gases from coal-fired power generation arise mainly from the combustion of the fuel but significant amounts are also emitted at other points in the fuel supply chain. The IEA Greenhouse Gas R&D Programme has investigated many technological options for reducing these greenhouse gas emissions. These include methods of reducing CO2 emissions from new and existing power stations, as well as methods of reducing emissions of other greenhouse gases, for example methane emissions from coal mining. The IEA Greenhouse Gas R&D Programme is an international collaboration, supported by 16 countries, the European Commission and 7 industrial sponsors. Australia participates in the Programme through a consortium which involves electricity and natural resources companies, and fuel and energy research organisations. This paper will provide an overview of studies in 3 areas: • Methods for reducing emissions from existing coal-fired power plant • Capture of CO2 from coal-fired power plant with subsequent storage in underground reservoirs • Methods for reducing methane emissions associated with the mining of coal. The retrofitting of existing plant can achieve significant reductions in CO2 emissions (ranging from 2-50%) although the cost-effectiveness varies depending on the technology, the location of the plant and the depth of emission reduction. With new plant, the use of technologies for the capture of CO2 with subsequent storage could make deep reductions (e.g. 75%) in the emissions. Such technologies cost considerably more than simple retrofit measures but are competitive with other ways of achieving deep reductions in greenhouse gas emissions which typically involve the use of another energy source in place of coal. Some abatement of the methane emissions from underground coal mining can be achieved at very low net cost but deep reductions in these emissions would require action on the main source, ventilation air, which would be more expensive. Nevertheless, such measures are worth considering because of the high global warming potential of methane and because, unlike CO2, the energy content of the captured gas can be utilised. Carbon Management Options for Coal-Fired Utility Boiler Systems. 29-2

The Separation and Sequestration of CO2 from Coal-Fired Boiler Flue

Gases: a Biomimetic Approach

Gillian M. Bond, Margaret-Gail Medina, New Mexico Tech, John Stringer, EPRI, USA

A large part of the world’s electricity is generated using systems based on coal-fired boilers raising steam which is expanded through turbines driving a generator. Typically, this Rankine cycle operates at an overall efficiency of perhaps 35%, and for every 1 MW(e) capacity, 1 tonne (metric ton) of CO2 is produced per hour. Separation from the exhaust gas is possible using a number of methods, but safe sequestration presents a number of problems. Biomimesis is a method of approach to a variety of problems that can be summarized as follows: (1) We have a problem. (2) Is there an equivalent problem in natural systems? (3) If so, how is it dealt with? (4) Can we imitate those methods to solve our problem? In the distant past, the CO2 concentration was significantly higher than it is now. It decreased as a result of the formation of stable carbonate minerals, the majority of which are based on CaCO3 and MgCO3. A major method for the formation of limestone involved the formation of calcium carbonate by a variety of marine biota, including for example the growth and shedding of shells, which then accumulated on the sea floor, where it was then compacted. The resulting limestone formations have been stable over more than 200 million years. How do marine animals form carbonate shells? The rate-controlling process involves catalysis by an enzyme, carbonic anydrase, of a reaction forming a bicarbonate ion from dissolved carbon dioxide. The enzyme is capable of extremely high rates of reaction, and thus imitation of this natural process seemed an interesting possibility: forming an extremely stable

33

environmentally neutral product using an enzyme that is present in all living things. Of course, a number of significant problems have had to be addressed: (a) does the process work in an environment different from that in the shell gland of a marine mollusk? (b) Is the enzyme poisoned by impurities expected in a coal combustion exhaust gas? (c) Can we find a way to produce the enzyme in large quantities? (d) Can we immobilize the enzyme (to keep it from being washed away in the process stream)? (e) How sensitive is the reaction to temperature, and to pH? (f) Can methods be found to counter local changes in chemistry associated with the reaction itself(e.g., can the reaction be buffered)? (g) Given the bicarbonate product from the enzyme-catalyzed step, can we precipitate carbonate rapidly given a suitable cation (e.g. calcium)? (h) Where is the cation going to come from? (i) What are the required process mass flows for a typical power station, and are these reasonable? To date, acceptable answers have been found for most of these questions; but some significant problems still exist. This paper will describe the current status of the research, and what still needs to be done. 29-3

Enhanced Practical Photosynthetic CO2 Mitigation

David J. Bayless, Greg Kremer, Morgan Vis, Ben Stuart, Michael Prudich, Ohio University, K. Cooksey, Montana State University, J. Muhs, Oak Ridge National

Laboratory, USA

Biological carbon emission mitigation offers many advantages for small- and medium-sized fossil generating stations, including lower capital cost and lower heat rate penalty. Besides being the natural process to recycle carbon, photosynthesis produces a byproduct, biomass, which has numerous beneficial uses, including as a potential source of hydrogen gas. It also can be used to accelerate sequestration in terrestrial systems. Despite the large body of research in photosynthesis, virtually no work has been done to create a practical photosynthetic system for greenhouse gas control for use with both new and existing fossil units. For example, use of a raceway cultivator (or microbial pond) often ignores land availability limitations and numerous problems of flue gas sparging. The work presented in this paper, partially funded by the Department of Energy under grants DE-FG2699-FT40592 and DE-FG2600-NT40932, describes the design and development of an cost-effective engineered photosynthesis system for CO2 recycling that is estimated will require approximately 1/20th the surface of a microbial pond. The project, directed by Ohio University, incorporates thermophilic organism research at Montana State University and design work the Oak Ridge National Laboratory to better utilize full-spectrum solar energy. Research has focused on selection and study of viable thermophilic organisms, design of the growth surfaces within the bioreactor to reduce overall system size, photon collection and delivery via fiber optics to optimize growth and reduce system footprint, and sustainable harvesting schemes to facilitate maximum growth rates. Research has also been directed to the application of translating slug flow technology to enhance concentrations of soluble carbon species to increase organism growth rates and to reduce flue gas temperatures to sustainable levels. Results have indicated that thermophilic and mesophilic organisms can grow in a sustainable fashion within the bench scale bioreactor, reducing CO2 levels by approximately 20%. Future work will focus on scale-up, improving CO2 capture levels, and enhancing process sustainability. 29-4

Economic Analysis of Carbon Sequestration on Reclaimed Mined Lands

Ching-Hsun Huang, Gary D. Kronrad, Stephen F. Austin State University, USA

In 1997, the Kyoto Protocol was proposed as a means of curbing global warming. This treaty defines a general goal for Europe, Russia, Japan and North America to reduce their greenhouse gas emissions 5.2 percent below their 1990 level between 2008-2012. Carbon dioxide (CO2) emissions can be reduced through government regulations, carbon tax or carbon sequestration. Reducing CO2 emitted into the atmosphere would require a significant reduction on the use of fossil fuels. This could cause massive unemployment, higher prices for energy, inflation and the potential disruption of an economy. Imposing a tax on emissions will increase the price of goods and services resulting in negative economic effects. The new administration has decided that limiting the use of fossil fuels or imposing a tax are unacceptable. The only acceptable option is removing CO2 from the atmosphere and storing it as carbon. Enhancing carbon sequestration in trees on reclaimed mined lands is an economically and environmentally sound alternative. There are approximately 148,500 hectares (377,000 acres) of unreclaimed mined lands in the United States. Reclamation and reforestation of these lands has great potential to sequester carbon in terrestrial ecosystems. In addition, it is expected that large reforestation projects

will increase environmental benefits, create jobs and affect the local economy through the multiplier effect. These mined lands have not been reclaimed because the costs of reforestation and management may exceed timber revenue. Forest management would become profitable in most cases if mined lands owners could earn revenue from the sale of carbon credits. Each ton of carbon sequestered is called a carbon credit and can be used to offset emissions, traded by one company to another company, or sold on the open market. The major users of fossil fuels, like the utility companies, may be willing to pay landowners for each ton of carbon they sequester or to share management costs with landowners. This additional revenue will give landowners an incentive to plant and manage their forests. This carbon credit market will benefit both the utility companies and landowners. Before large-scale investments will be made, two basic questions must be answered: 1) How much carbon can be stored in a forest? and 2) How much does it cost to store a ton of carbon in a forest? Results from loblolly pine plantations in the southern U.S. indicate that the costs to sequester a metric tonne of carbon range from a high of $9.03, on poor quality land, to a low of $2.95, on good quality land. Over one rotation, approximately 108 tonnes may be sequestered on poor quality land and 196 tonnes on good quality land. Sequestering carbon in forests on reclaimed mined land is an inexpensive, efficient and environmental friendly method of slowing global warming while increasing forest yields and other desirable ecosystem goods and services. 29-5

Sequestration of CO2 in a Depleted Oil Reservoir: Numerical Simulations

Related to a Field Demonstration

Rajesh Pawar, Dongxiao Zhang, Los Alamos National Laboratory, Charles Byrer, U.S. DOE/Fuel Resources Division, Henry Westrich, Sandia National

Laboratories, USA

Permanent disposal of CO2 in geologic formations, especially in oil and gas reservoirs, is thought to be a safe and effective carbon sequestration strategy. Because interactions between CO2 and the geologic formations are very complex, additional R&D efforts are needed to fully understand geologic sequestration of CO2. DOE/NETL is funding this project to better understand, predict and monitor the migration and fate of injected CO2 in a depleted, sandstone oil reservoir. The West Pearl Queen field, located in SE New Mexico, is our field demonstration site for CO2 injection. Our project combines geologic, flow and reaction path modeling and simulations, injection of CO2 into an oil-producing reservoir, geophysical monitoring of the advancing CO2 plume and laboratory experiments to measure reservoir changes with CO2 flooding. The field demonstration provides a unique opportunity to test, refine and calibrate the computer model(s) that will simulate those subsurface interactions. This part of the project has three phases: I) baseline reservoir characterization, II) injection of over 2000-3000 tons of CO2, followed by soaking, and III) final reservoir characterization after wellhead venting and pumping. Advanced modeling and flow simulation techniques were used to develop a geologic model of the site and to verify the feasibility of CO2 injection into that reservoir. These simulations are being used to guide geophysical survey parameters and to bound test conditions for lab experiments. Preliminary flow simulations were run using this data (ECLIPSE code) to simulate the coupled processes that occur during injection and migration of CO2 in the depleted oil reservoir. Results suggest that at least 2000 tons of CO2 can be injected into the reservoir over a period of one month. Remote geophysical sensing techniques will be used prior to, during and after CO2 injection. Borehole geophysics, surface to borehole surveys, and surface reflection seismic surveys will identify and characterize formation changes due to saturation and injection effects. They will include limited microseismic surveys during injection, and multi-level, 3C crosswell seismic surveys, vertical seismic profiles and 4D, 9C seismic surveys that will be run before and after injection. Static and dynamic laboratory experiments, using actual core samples of the Queen sandstone under anticipated reservoir conditions, will explore the effects of fluid chemistry and flow on mineral dissolution and precipitation reactions as well as their effects on rock porosity and permeability. Reaction path calculations of produced brine compositions will be compared to analyses of experimental fluids and post-injection aqueous well samples to better understand the mechanisms and rates of CO2-mineral interactions in a depleted oil reservoir. Our planned suite of computer simulations, laboratory tests, field measurements and monitoring efforts will be used to calibrate, modify and validate the modeling and simulation tools for CO2 injection in an oil reservoir. Ultimately, the models and data will be used to predict storage capacity and physical and chemical changes in reservoir properties, such as fluid composition, porosity, permeability, and phase relations. Science or technology gaps related to engineering aspects of geologic sequestration of CO2 also will be identified during the course of this study.

34

SESSION 30 PYROLYSIS AND DIRECT COAL CONVERSION-II

30-1

Development of Upgrading Technologies for Coal-derived Oil

Katsumi Omori, Hidemi Sato, JAPAN

Coal liquefied oil as an automobile fuel requires upgrading in quality because it contains a large amount of impurities. The New Energy and Industrial Technology Development Organization (NEDO) has constructed a process development unit (PDU) to upgrade coal liquefied oil. The design capacity of the unit is 40 bpd to obtain engineering data which are used in the scaling up of the plant to commercial size. The construction of the PDU was completed in December 1999, and first-stage hydrotreatment started in March 2000. During the operation, operating conditions were varied to determine their influence on the properties of the products. A slight deactivation of the catalyst was observed in the eighth month of operation. Process stability is proved by the 4,000 hours of continuous operation. 30-2

Understanding the Volatilisation of Alkali and Alkaline Earth Metallic

Species during the Pyrolysis of Victorian Brown Coal

Chun-Zhu Li, Hongwei Wu, Dimple Quyn, Chirag Sathe, Monash University, AUSTRALIA

The volatilisation of alkali and alkaline earth metallic (AAEM) species (mainly Na, Mg and Ca) is one of the most important considerations in the process design for the utilisation of Victorian brown coal, particularly in the gasification/reforming-based power generation systems. The purpose of this study is to examine the main factors influencing the volatilisation of AAEM species during pyrolysis. Pyrolysis experiments were carried out in a number of novel reactors, including a wire-mesh reactor, a one-stage fluidised-bed/fixed-bed reactor and a two-stage fluidised-bed/fixed-bed reactor. From these experimental results, the main factors influencing the volatilisation of AAEM species are the valence, chemical and physical forms of AAEM species in the coal and the pyrolysis experimental conditions such as temperature, holding time and carrier gas velocity and the type/reactiveness of gas surrounding the particles. The interactions between the nascent volatiles and char also greatly affect the retention of AAEM species in the char during pyrolysis. Our experimental data indicate that the monovalent species (Na) was more easily volatilised than the divalent species (Mg and Ca) during pyrolysis. Na in the form of NaCl in the coal substrate was more easily volatilised than Na in the form of carboxylates. The interactions between the evolved volatiles (radicals) and the nascent char, which were influenced by the sweeping velocity of the carrier gas, played a very important role in the volatilisation of AAEM species. In the absence of extra-particle volatile-char interaction, temperature was the most important factor influencing the volatilisation of these metallic species during pyrolysis, with heating rate playing negligible roles at temperatures up to 900°C. The gas atmosphere surrounding the coal/char particles was another important factor controlling the volatilisation of these AAEM species. An oxidising environment (O2 or CO2) tends to favour the retention of the AAEM species. 30-3

Effects of Additives and Pretreatment on Pyrolytic Desulfurization and

Denitrogenation of Coal

Haoquan Hu, Qiang Zhou, Lifen Liu, Dalian University of Technology, Shengwei Zhua, Dalian University of Technology, Guohua Chen, Dalian University of The Hong Kong University of Science & Technology, P. R.

CHINA

Three coals, Datong (Vdaf 34.84%), Pingsu (Vdaf 42.02%) and Shenfu (Vdaf 43.86%), and their acid-washed samples were pyrolyzed in a fixed bed reactor at different atmosphere and pressure up to 2MPa. The experiments were carried out to investigate the effects of additive, such as Fe, Ca contained compounds and some H2S trapping materials, and pretreatment, such as steam, alkalis, on desulfurization and denitrogenation, changes in sulfur, nitrogen forms, and the influence of inorg. matter on sulfur transformations during pyrolysis of coals. The results indicated that the existence of Fe in nano-meter size is benefit to convert the N in coal to N2; Ca will increase the S retention in coal pyrolysis char; Alkali treated coal was effective for reduction of organic sulfur while steam pretreatment followed by pyrolysis is benefit to both inorganic and organic sulfur removal. According to the analysis of S, N forms and content in

original, pretreated coal samples and different products, the reaction mechanism and structure of sulfur were discussed. 30-4

Swelling Behaviour of Coal During Pyrolysis

Vladimir Strezov, John A. Lucas, University of Newcastle, Les Strezov, BHP

Minerals Technology, AUSTRALIA

Coals heated at a prescribed heating rate undergo significant changes when reaching their plastic stage. Rapid evolution of tars and volatiles are involved with pronounced swelling of the char. In the current work a study of the coal swelling during continuous heating is presented. The physical changes during heating of a single coal particle were observed and recorded using a long distance focal microscope attached to a CCD camera. The coal particle was recorded at a 100 times magnification during its heating. The samples with different plastic properties were selected for this study. Rapid bubble formation and swelling was observed during the heating of the plastic coals, while the coals with lower plastic properties showed little or no swelling, although the evolution of the tars and rate of weight loss were at their maximum. The weight loss and tar evolution of the samples were measured with a Thermogravimetric Fourier Transform Infrared Analyser (TG-FTIR). Pressure drop across the heated coal bed was also measured using an absolute pressure cell. The pressures were found to have a maximum during the plastic stage and coincided with the coal swelling behaviour. 30-5

Research on Coal Quality Changes by Rapid Preheating

Kenji Kato, Koji Saito, Makoto Matsuura, Nippon Steel Corporation, Ikuo Komaki, The University of Kitakyusyuu, JAPAN

Development of new cokemaking process, SCOPE21, has been conducted in Japan since 1994 by the Japan Iron and Steel Federation. A basic concept of the SCOPE21 process is a great improvement of the coke productivity. Here the coal preheating technology is very important, and the study of coal properties improvement under rapid preheating was undertaken by means of NMR, FT-IR, and the ultimate analysis, etc. The effect of the rapid preheating of coals on coke strength was investigated, it was ascertained that the preheating of coal made it possible to increase the ratio of non-or slightly coking coals in the coal blend, while still maintaining acceptable coke properties. As a result, it has been understood that coke strength is improved due to the rapid preheating processing, and the use ratio of non-or slightly coking coals in the coal blend can be raised. Here, it was observed that the formation of bridge reactions, which takes place under slow-heating, was suppressed under rapid preheating and at the same time, the mobility of molecules in coal was enhanced by the rapid preheating. Therefore, it is thought that the caking property of coal was improved by rapid preheating due to these factors. It was clarified to be able to improve the coal caking properties by applying the rapid heating technology at this time. Once the SCOPE21 process is developed, this findings will be examined in the case of an actual industrial process in the future.

SESSION 31 COAL PRODUCTION AND PREPARATION-II

31-1

On-Belt Analysis of Coal

C. S. Lim, D A Abernethy, S Rainey, J R Tickner, CSIRO, AUSTRALIA

A new neutron and gamma-ray analysis system has been developed for the direct on-conveyor belt analysis of ash in coal. This new analysis system incorporates a method for ash measurements which are independent of changes in segregation, belt loading and composition. As a result, the new system provides greater accuracy than on-belt Dual Energy gamma-ray Transmission (DUET) gauges (such as the Coalscan 2500 and 3500) but at a much lower cost than by-line Prompt Gamma-ray Neutron Activation Analysis (PGNAA) analysers such as the Coalscan 9500. The analyser simultaneously measures neutron inelastic scatter and thermal neutron capture gamma-rays from bulk coal samples. Laboratory tests of the technique have been performed on 24 bulk (about 70 kg) run-of-mine and product coal samples of thickness from 100 to 300 mm and ash from 8 to 31 wt.%. The standard deviation of the chemically measured ash values of these

35

samples has been estimated to be 0.5 wt.% using the Grubbs estimation method. Calibration and cross-validation r.m.s. errors of between 0.46 and 0.55 wt.% ash have been achieved for the laboratory measurements, indicating that the technique is capable of significant improvement in accuracy but is currently limited by the sampling and chemical laboratory error. A prototype based on this work has been designed and tested under industrial conditions in the laboratory using 50 bulk coal samples with ash ranging from 6% to 35%. The results of these tests will be presented. New features in the analyser design, such as improvements to detector temperature control and radiation shielding, will also be discussed. These changes make the analyser far more suited to long-term use in industrial conditions and relatively cheap to construct at a commercial level, without compromising technical performance. 31-2

Modelling of Coal Breakage in Sample Pretreatment

Andrew Swanson, Ian Fletcher, Quality Coal Consulting Pty Ltd, AUSTRALIA

The breakage of coal and the consequent size distributions are fundamental to the proper consideration of coal handling and preparation. Plant design depends upon knowledge of in plant sizings and only properly pretreated samples can provide meaningful washability data for planning and projection. There has been appreciable development of pretreatment techniques over the last ten years in Australia and the work has been well supported by government and industry funding.. This paper will describe the breakage patterns observed in a number of Australian mines that has led to the development of a conceptual model for breakage. The paper will describe this model and outline how it relates to the recommended pretreatment methods. The elements of a pretreatment procedure and its application are reviewed. 31-3

Design Optimization of Dense Medium Cyclones using Computational Fluid

Dynamics

D.J. Suasnabar, R&D, A.C. Partridge, UNSW, C.A.J. Fletcher, CANCES, AUSTRALIA

Dense medium cyclones (DMCs) provide a treatment process which cleans coal effectively but their design could be improved. Better DMC design would make it possible to reclaim more and/or cleaner product coal. Changes may only mean a small improvement in cyclone efficiency, but when each cyclone processes hundreds of tonnes of coal per hour, such minor improvements become of major significance. Due to the complexity of the flow and the high concentration of solids in the feed slurry, detailed experimental investigation of the flow and particle interaction inside dense medium cyclones is extremely difficult. With a lack of detailed information on what is going on inside cyclones, a comprehensive optimisation of the design is out of the question. Traditionally, design and efficiency improvements of DMCs have depended heavily on experimentation. Correlations of experimental data to produce empirical expressions for pressure drop, flow rates, coal particle separation efficiency, etc. as a function of geometrical parameters and operating conditions have been carried out. Unfortunately, however, these relationships can only be used within the operational boundaries in which they were obtained. Extrapolations are open to question, and their validity is usually uncertain. Therefore there is a need for a more general approach. Computational Fluid Dynamics (CFD) offers an alternative way to obtain insight into the physical processes and flow interactions of DMCs. A validated numerical CFD model can also be used to carry out design modification for optimisation of the particle separation beyond the standard design. However the complex nature of the flow and particle interactions in DMCs make the development of a computational model for these devices a challenge. Prior to our work there was no model that fully accounts for the three-dimensional features of the flow and uses a general turbulence model that can provide an overall model for optimisation purposes. The only computational model for DMCs (Zughbi et al., 1991) is an oversimplified approach in which an axisymmetric assumption and the Prandtl mixing-length turbulence model were used. Extensive models developed for hydrocyclones are available but are not readily applicable for DMCs due to the major operational differences between these devices. The research described in the proposed conference paper used CFD to build a comprehensive computational model for DMCs. The model has been employed to investigate fluid flow and particle interaction. It successfully predicts density

differentials within the media and, by tracking individual particles of different densities and sizes, generates partition curves with the shape and Ep and cutpoint values in agreement with those determined conventionally. The model has been used to carry out a systematic design modification of cyclone geometry aimed at a sharper separation of fine coal particles, resulting in a new design which corresponds closely with one independently determined empirically by others (Rong and Napier-Munn, 8th Australian Coal Preparation Conference, 2000). This result indicates that further development may be carried out efficiently and with confidence using the CFD model. 31-4

Pilot Plant Hydrosizing Trial of the Reflux Classifier

K.P. Galvin, E. Doroodchi, G. Nguyentranlam, A. Callen, N. Lambert, S.J.

Pratten, University of Newcastle, AUSTRALIA The Ludowici LMPE Reflux Classifier is a new device for separating particles on the basis of either size or density. Water flows up through a distributor plate at the base of the device, suspending particles within the vessel. A set of parallel inclined plates amplifies the segregation rates of the particles, causing slower settling particles to pass through the zone of inclined plates, while retaining the faster settling particles below. Additional separations are produced within the one vessel through the use of more than one set of parallel inclined plates, thus providing a middlings stream, or a recovery of the fluidization water, for example. The inclined plates, which effectively increase the sedimentation area of the vessel, permit remarkably high throughputs. In this paper the results of a pilot plant trial of the Reflux Classifier are presented. The focus of the paper is on the influence of the fluidization velocity on the separation size, and the effect of increasing the throughput on the partition curves. The inclined channels function as hydraulic screens, providing the opportunity to vary the separation size by simply changing the fluidization rate. The spacing between the plates is very much greater than the particle size. The inclined plates permit a broad range of possible suspension concentrations to evolve at a given fluidization rate. A theoretical model that accounts for this effect is presented. Thus, when subjected to a step change in the feed condition, the system evolves naturally to a new steady state concentration, with relatively little change occurring in the separation condition due to the change in the level of hindered settling. The system is therefore self-controlling. 31-5

On-Conveyor Measurement of Moisture in Coal Using Low Frequency

Microwaves

N.G. Cutmore, D.G.Miljak, T.G.Rowlands, D.Crnokrak, A.J.McEwan, CSIRO, AUSTRALIA

The measurement of the moisture content of materials is a key control parameter in a very wide range of industrial processes. This has been, and in many cases still is, carried out by manual or automatic sampling of product from the process, followed by conventional laboratory analysis by oven drying. However, although this procedure enables the moisture content to be routinely monitored it is frequently too slow for process control purposes. Consequently, there is a strong interest in on-line techniques for the accurate and rapid measurement of moisture in materials carried on conveyors, in chutes, in pipelines, etc. Microwave based techniques have emerged over the past 40 years as the dominant technology for on-line measurement of moisture in bulk materials. The phase shift of the microwave transmitted through the material under test generally demonstrates the best correlation with moisture content. The advantages of microwave transmission techniques for on-line measurement of moisture are that they are rapid, non-contacting, interrogate a large fraction of the material volume, and are insensitive to an inhomogeneous distribution of moisture as may occur in the layering of materials carried on a conveyor. Conventional measurement applications in the coal industry have involved on-conveyor measurement of feed and product coals in coal preparation plants and feed coals to power stations. These applications generally require the analysis of 50-250 mm thick beds of coal, typically at moisture contents in the range 10-20 wt.%, and microwave transmission based analysers have been used successfully for a number of years. However, there are a number of applications (e.g. coal loaders, lignite and ROM black coal), requiring the analysis of coal at large bed depths and/or high moisture contents, that are not amenable to on-conveyor moisture analysis with presently available microwave analysers due to an unacceptably high attenuation (>50 dB) of the transmitted microwave signal. This limitation is due to the leakage of the microwave signal around the material bed (on a conveyor) being sufficiently large, compared to that transmitted though it, that the signal/noise is unacceptable.

36

A low frequency microwave technique has now been developed that is suited to both the more conventional coal applications and those that were previously too difficult. This increased performance in measurement accuracy has been achieved through utilising microwave developments for mobile communication applications that typically span the 0.9-1.8 GHz frequency band. A commercial prototype low frequency moisture analyser has been under development for the past two years. The main criteria in the design of this analyser are: reduced hardware cost; increased accuracy and dynamic range of measurement; and an interactive user interface to simplify analyser calibration and use. The first two commercial prototype analysers were installed on the ship-loading conveyors at Dalrymple Bay Coal Terminal (Queensland, Australia) in early 2001, where they will monitor ~30 Mtonne/annum of shipped coal on conveyors carrying up to 10,000 tonne/hr. The performance and on-line calibration of these analysers are described. 31-6

Dewatering of Ultrafine Clean Coal slurries Using Modified Approaches

B.K. Parekh, D.Tao, University of Kentucky, Z.Chen, BetzDearborn, USA

Dewatering of fine coal slurry to less than 20 percent moisture using conventional equipment is generally not achieved. Coal industry is reluctant to use chemicals for dewatering as it increases the processing cost. This paper describes results obtained with two different novel approaches for dewatering of the fine coal slurry. The first approach utilized was a combination of vacuum and pressure in two stages. Using this approach, moisture reduction of more than ten absolute percentage points was obtained. The second approach involved applying periodic breaks in the vacuum during drying cycle, this approach reduced filter cake moisture by five absolute percentage points. The paper also describes the basic principles of the process.

SESSION 32 GASIFICATION: FUNDAMENTALS-1

32-1

High-Pressure Intrinsic Char Gasification Kinetics: The Application of a

Modified nth Order Rate Equation

D. G. Roberts, T. F. Wall, CRC for Coal in Sustainable Development, D. J. Harris, CSIRO Energy Technology, AUSTRALIA

Recent work to determine chemical rate data for the reactions of coal chars with CO2 and H2O have reported pressure effects on the reaction order, n. This indicates that in its standard form, the nth order approximation to the rate equation:

ng

ag P

RTE

A ⋅

−

= expρ

(where ρg is the reaction rate, A is the pre-exponential factor, Ea is the activation energy, R is the gas constant, T is the temperature and Pg is the partial pressure of reactant gas) is not suitable for extrapolation of low-pressure chemical rate data to the high pressures found in emerging combustion and gasification applications. The work presented in this paper extends the previous measurements made in this laboratory and analyses the fundamental processes occurring on the char surface as the pressure of reactant increases. This has led to the development of a model that predicts the decrease in reaction order n as the pressure increases, based on the saturation of the available char surface. It is shown how this model can predict the reaction rate as a function of pressure using the (modified) nth order equation. Further work is required to refine this model: the generation of such data being the subject of ongoing investigations in this laboratory. 32-2

The Slag Flow Characteristics of Australian Bituminous Coals in

Entrained-Flow Slagging Gasifiers

J.H Patterson, H.J.Hurst, A.Quintanar, CSIRO Energy Technology, R.K Boyd, H.Tran, Pacific Power International, AUSTRALIA

Interest in advanced power generation technologies based on integrated gasification- combined cycle (IGCC) remains strong, albeit using cheap waste materials rather than coal. Over the last six years the CSIRO and the Cooperative Research Centre for Black Coal Utilisation has been evaluating the slag flow characteristics and flux requirements of Australian bituminous coals. This paper will summarize the latest results of the work and update a series of papers presented at previous Pittsburgh Coal Conferences. The suitability of Australian bituminous coals from an ash and slagging viewpoint, has been

confirmed for use in entrained- flow slagging gasifiers which form the basis for more efficient power generation technologies based on IGCC. A number of coals appear suitable without flux addition and about half of the coals examined are shown to require a limestone flux addition of 3% by weight of coal at a tapping temperature of 1450 C. Such coals would appear suitable for use in blends with other coals. Blending of Australian high ash fusion coals with other low ash fusion coals can reduce or eliminate the need to add a limestone flux. The efficacy of coal blending will be demonstrated for reducing flux requirements and overcoming limitations which can arise from slag crystallization. A number of empirical viscosity models have been developed for Australian coal ash slags, to enable prediction of flux requirements for continuous slag tapping. Ways to reduce the temperature of critical viscosity will be demonstrated and a method of relative coal value modeling has been developed and applied for economic optimization of limestone flux addition and gasification temperature. 32-3

Applications of the Coal Ash Slag Viscosity Model for the Slagging

Gasification Technologies (Viscosity Model in the Al2O3-CaO-“FeO”-SiO2 System)

Alex Kondratiev, Evgueni Jak, CRC for Coal in Sustainable Development,

AUSTRALIA

Coal ash flow characteristics are predicted and applied to selection of blending and fluxing in coal slagging gasification processes. A new viscosity model has been developed for these purposes, which enables the viscosities of coal ash slags to be predicted as a function of temperature and composition in the Al2O3-CaO-“FeO”-SiO2 system under reducing conditions (in equilibrium with metallic iron). In addition to the viscosities of the completely liquid slag systems, the new model describes viscosities of the heterogeneous, partly crystallised slags at temperatures below liquidus. This new viscosity model incorporates the following major advances. i) The Urbain formalism has been significantly modified to describe the viscosities of the liquid slag phase over a wide range of temperatures and the complete range of compositions from the pure oxide, binary and ternary to the multi-component quaternary ash slag systems. ii) New set of the parameters for the liquid slag phase has been derived from the extensive experimental set including the most recent experimental data. iii) New thermodynamic database for this chemical system developed by the authors is used in conjunction with the computer package F*A*C*T to predict the proportion of solids and the composition of the remaining liquid phase for temperatures below liquidus. This information from F*A*C*T is essential for prediction of the partly crystallised coal ash slags and forms the basis of the viscosity model. iv) The description of the effect of presence of solid suspension (slurry effect) on the viscosity is derived from the extensive experimental data set for temperatures below liquidus, with application of the Roscoe equation. The model provides a good description of the experimental data in liquid ash slag phase, and liquid + solid mixtures, over the entire range of compositions and a wide range of temperatures. This model is now used for viscosity predictions in industrial slag systems. Coal fluxing: Applications of the new model to coal ash fluxing and blending for coal slagging gasification processes will be described in the paper. The effects of CaO and FeO flux additions on the proportions of solids formed and viscosities of the coal ash slag are complex and require careful investigation. The detailed comparison of the effects of the flux additions of calcium oxide, iron oxide and their mixtures at various proportions will be presented for the coal ash slags with a wide range of the SiO2 /Al2O3 ratios. Coal blending: Blending can effectively be used to control coal ash slag melting and flow behaviour in coal slagging gasification technologies. Selection of the most effective combination of the coals and their blending proportions is a difficult task. The application of the new viscosity model in conjunction with the F*A*C*T thermodynamic computer package enables systematic analysis of the melting and flow characteristics of the coal blends to be performed and coal blending strategy to be optimised to achieve the best results. Selection of the optimum two-coal and three-coal blends with regard to the melting behaviour and ash slag viscosity will be presented in the paper. The new viscosity coal ash slag model in combination with the thermodynamic computer package F*A*C*T is a powerful tool for the most effective use of the coal in slagging gasification technologies with regard to the melting and viscous flow characteristics of the coal ash slags.

37

32-4

Effects of Experimental Conditions on the Conversion of Coal-N during the Gasification of a Victorian Brown Coal

Chun-Zhu Li, Fujun Tian, Liping Chang, Zongli Xie, Jun-ichiro Hayashi,

Monash University, AUSTRALIA, Tadatoshi Chiba, Hokkaido University, JAPAN

Coal will continue to be the main energy source in many parts of the world in the foreseeable future. The use of coal as our energy source in the future will depend strongly on the minimisation of its environmental impacts particularly the emissions of greenhouse gases (eg. CO2 and N2O) and air pollutants (eg. NOx). There is little doubt that the development of gasification/reforming-based technologies (eg. APFBC and IGCC) will contribute to the reduction of CO2 emissions. However, the emissions of nitrogen oxides (N2O and NOx) must also be minimised for these new technologies to be viable in the future. The best strategy for the reduction of the nitrogen oxides emissions will ultimately rely on the understanding of the formation of NOx and NOx precursors (eg NH3 and HCN) during gasification. The purpose of this study is to investigate the mechanisms of the reactions that are responsible for the formation of NOx, N2O and NOx precursors (mainly HCN and NH3) from the nitrogen in coal during gasification. A Victorian brown coal is gasified in a set of novel reactor systems using CO2, steam and air as gasifying agents. The yields of NOx, N2O, N2 and NOx precursors are quantified as a function of gasifying agent type, reaction temperature and holding time at the reaction temperature. Based on our experimental data, the reaction pathways leading to the formation and destruction of NOx, N2O and NOx precursors will be discussed in this paper. 32-5

A Generalised Mathematical Model of Underground Coal Gasification

Andrew C. Beath, Cliff W. Mallett, Michael Wendt, CSIRO Exploration and

Mining, AUSTRALIA

Underground coal gasification (UCG) has had several different stages of development worldwide, most notably a series of commercial-scale sites in the former Soviet Union since the 1930s, extensive trials in the USA in the 1970s and trials during the last decade in Western Europe and China. At each stage of development there have been improvements in the techniques used and an increase in the coal resources that can be feasibly extracted using UCG. However, the economic viability of the process is influenced by the cost of other energy sources, mainly mined coal, natural gas and oil, and full commercialisation of UCG has been hindered by fluctuations in these costs. Recent increases in the prices of natural gas and oil, and foreseeable shortages in some regions, have led to renewed interest in UCG as a source of natural gas substitute or synthesis gas for the production of synthetic liquid fuels. This usage of the product gas requires that accurate control be maintained over the composition and flow rate from the UCG site and it is therefore important to develop a better understanding of the processes occurring in the gasifier. As an aid to development of an advanced model-based control system, a model of the underground gasification process has been developed. This model is intended to provide a representation of underground coal gasification that is both realistic and applicable to a wide range of different geological sites and gasification techniques. Some of the processes and characteristics that have been considered in the model include the ingress of water from surrounding geological strata, the changing volume and shape of the gasification chamber with reaction, the collapse of parts of the cavity roof into the cavity and the dual reaction sites of the cavity walls and combustible rubble components. In addition to these there are the ‘typical’ model components involving coal drying and reaction, gas flow, heat transfer and coal/char structures consisting of large wall and smaller rubble elements. The model is analysed with regard to the realism of assumptions made and the accuracy of predictions made when compared to published experimental results from UCG trials.

SESSION 33 SYNTHESIS GAS CLEANING-I

33-1

Experimental Studies In Support of the Ultra-Clean Gas Cleanup Process

Development1

Rachid B. Slimane, O. Mehmet Akpolat, and Francis S. Lau, Gas Technology Institute, Richard A. Newby, Tom E. Lippert, Siemens Westinghouse Power Corporation, Keyur Pandya Javad Abbasian, Illinois Institute of Technology,

Suresh C. Jain, U.S. Department of Energy, National Energy Technology Laboratory, USA

The Siemens Westinghouse Power Corporation (SWPC) and the Gas Technology Institute (GTI) are developing an innovative process for hot syngas cleanup, the “Ultra-Clean Gas Cleanup Process,” to meet the needs of advanced IGCC-based co-production of electric power and chemical or fuel products. This process has two cleanup stages integrated in series, that will reduce the concentrations of the primary contaminants (H2S, HCl, particulates) to about the 1 ppm level in the first stage, a moving-bed filter-reactor, and will further reduce the contaminant concentrations to the required ppb levels (i.e., H2S < 60 ppbv; HCl < 10 ppbv; particulates < 100 ppbw) in the second stage, a barrier filter-reactor. This paper reports on experimental work conducted at GTI to generate laboratory reaction conversion performance test data under operating conditions closely simulating process requirements. This investigation has systematically considered suitable Cu-, Fe-, Mn-, and Zn-containing fines and Na-containing fines as desulfurization and dechlorination materials, respectively, for both stages of the Ultra-Clean Gas Cleanup Process. The materials selected for both stages of the process, their chemical and physical characteristics, their desulfurization or dechlorination performance in a packed-bed reactor (screening and scoping tests), and the performance of physical mixtures of leading desulfurization and dechlorination materials are presented and discussed. Consistency of experimental data is demonstrated based on product gas analyses using gas and ion chromatographs (i.e., breakthrough curves), chemical analyses of spent samples from different locations in the sorbent bed, and X-ray diffraction analyses. Based on thermodynamic simulations and analyses, guidelines are developed to rationalize the experimental work and confirm or explain the results obtained. Gas sampling and measurement procedures, particularly ion chromatography techniques for the determination of HCl and H2S concentrations at the ppbv level, are described and their reliability and accuracy are demonstrated. On the basis of the encouraging laboratory-scale test results as well as technical and economic feasibility studies, SWPC/GTI will next undertake a bench-scale demonstration of the process performance, using an existing GTI gasifier, to provide evidence of commercial practicality. 33-2

Desulfurization Characteristics of Zinc Ferrite and Related Sorbents for

Hot Gas Cleanup Technology

Michihiro Ishimori, Masafumi Katsuta, Waseda University, JAPAN

In relation with the global environment issues, development of high performance coal thermal power plant is considered to be increasingly of importance. It has been noticed that Integrated Coal Gasification Combined Cycle (IGCC) and Integrated Coal Gasification Fuel Cell Combined Cycles (IGMCFC, IGSOFC) could be extremely high performance power plants, based on thermodynamic calculations. However, in order to realize these highly effective coal gasification power plants, development of highly efficient desulfurization technology for hot coal gas is required. We have studied zinc ferrite and related compounds as sorbents for hot reductive gas such as coal gas produced by an entrained-flow gasifier. The tests of capability of H2S absorption for the above sorbents were performed at 450 under atmospheric pressure at a fixed-bed type bench-scale reactor, using simple reductive gas containing 1000ppmv of H2S. Regeneration of the sorbent after sulfidation was carried out by oxidation with 2 % oxygen gas at 450. It was found that concentration of H2S involved in the reductive gas was decreased from 1000ppmv to 1ppmv by use of each above sorbent. Some sorbents such as ZnFe2O4-SiO2-ZrO2 system were found to be regenerable sorbents and tested over 4-6 cycles of H2S absorption and regeneration of the sulfided sorbents. The feature of H2S breakthrough curves is that all breakthrough profiles are almost identical, suggesting that deactivation of the sorbent during the absorption-regeneration cycles is negligible. The

38

characteristics of zinc ferrite and related systems will be discussed in terms of sorbents for hot-gas cleanup technology of IGCC system, in comparison with the hot-gas desulfurization (iron oxide) data obtained at Nakoso 200t/d IGCC pilot plant. 33-3

Multi-Cyclic Reactivity of Zinc-Based Sorbents for Hot Gas Cleanup

Si-Ok Ryu, No-Kuk Park, Tae-Jin Lee, Jae-Chang Kim, Yeungnam University,

Kyungpook National University, KOREA Integrated gasification combined cycle(IGCC) is considered as one of the most thermally efficient, economically attractive, and environmentally acceptable technologies for power generation from coal. The main components in an IGCC power plant are coal gasification unit, gas cleanup unit, and power generation unit. Hot gas desulfurization(HGD) is a very important process in the gas cleanup system and its main role is to remove harmful H2S and COS gases contained in the coal gas stream. Sulfur is a main precursor for acid rain and it causes severe damages in the systems. Since the higher concentration of H2S in coal gas can cause the corrosion of blades in gas turbine system as well as of electrodes in the molten carbonate fuel cell(MCFC), it is required to reduce the sulfur content in coal gas to the ranged from several thousand parts per million(ppm) to few ppm. Study on HGD for coal gas in IGCC has been concentrated on the development of metal oxide sorbents having the high sulfur removing capacity and the long-term durability in the ranged from high temperature to middle temperature. Of those ones, zinc titanate sorbents have been considered as one of the most favorable sorbents. The most important concerns for developing a highly efficient sorbent are sulfur capacity and durability. However, since the sorbents having high sulfur capacity requires high temperature for regeneration, it may cause deteriorations in the sorbents, such as spalling, cracking of pellets, progressive loss of reactivity over multiple sulfidation/regeneration cycles above 650. In this study the advanced zinc titanate sorbents(ZTG40) were developed for the highly effective desulfurization sorbents. The sorbents were prepared by the granulation method and the 100-cycle tests were carried out for durability and attrition resistance of the sorbents. Also, the changes of physical properties of the sorbents before/after reaction were investigated with the aid of XRD, SEM/EDX, Hg-porosimeter, BET. In the attrition tests for ZTG40 the results showed that the attrition resistance was 94.08% and that the sulfur capacity was 23.05g S/100g sorbent in the 100-cycle test. From the experimental results, ZTG40 has the desirable physical and chemical properties for desulfurization of coal gases and it will be suitable for fluidized-bed coal gas desulfurization systems. 33-4

Continuous Operation for 100 Hours in a Bench-Scale Fluidized Hot Gas

Desulfurization Process

Chang-Keun Yi, Sung-Ho Jo, Moon-Hee Han, Jae-Ek Son, Gyoung-Tae Jin, Korea Institute of Energy Research, KOREA

Most of researches of hot gas desulfurization sorbent development has been performed in batch cyclic test to see how much sorbents absorb sulfur of H2S and COS in reducing gas. However, It is not enough to see the real performance of the sorbent in batch cyclic test because the real hot gas desulfurization plant is operated at the continuous mode of sulfidation and regeneration in which the sulfur loading of the sorbent in the sulfider is maintained at low % level rather than at the level of maximum sulfur loading. Therefore, continuous operation should be needed to confirm the real performance of sorbent at last stage of the sorbent development. Continuous operation was done to see the long-term reactivity and the attrition resistance of the sorbent, the reliability of the process in a bench-scale KIER fluidized hot gas desulfurization process. A spray dried sorbent consisting of zinc-oxide was used. The pressure was maintained at 5 atm, the temperatures were 600 C and 700 C in the desulfurizer and the regenerator, respectively. Solids were circulated continuously and stably between two fluidized reactors at high pressure. Removal of H2S from the gas stream was consistently for 100 hours below 40 ppmv for a simulated coal gas containing 7700 ppmv H2S, that provided the basic data for the scale-up. The analysis of solid samples, such as sulfur concentration, SEM, XRD, size distribution, were contributed to uncover the characteristics of reaction and entrainment in two fluidized bed reactors.

SESSION 34 COAL COMBUSTION BYPRODUCTS UTILIZATION-I

34-1

Ash Utilisation – An Australian Perspective

Craig Heidrich, Ash Development Association of Australia Inc., AUSTRALIA

Australian producers and marketers of Power Station Ash formed the ADAA (Ash Development Association of Australia Inc.) in 1991. The primary objectives are to conduct research and technology transfer on behalf of members so as to exploit market opportunities in the use of Ash materials for all stakeholders. In achieving these objectives the ADAA have sort to increase user awareness of the benefits arising through the effective utilisation of this valuable industrial mineral by-product, which if realised, has benefits for industry, the environment and the community as a whole. For 1999 Ash produced approximated to 11,000,000 tonnes for Australasia. Of the total Ash produced some 5,500,000 tonnes can be said to have been effectively utilised. The main contributors are cementitious applications at approximately 1,165,000 tonnes, non cementitious applications at 347,000 tonnes, with the balance of 3,988,000 used in projects offering beneficial use (i.e. mine site remediation, local haul roads etc.) These applications and growth potentials will be discussed. The challenge for the membership ahead is identifying the next incremental step for the increased utilisation of domestic Ash production. The industry sectors participating in the use of Ash materials will be discussed, including new areas requiring greater research and investment. 34-2

Coal Combustion Products-Production and Uses: Coal Combustion

Products in 20th Century

Rustu S. Kalyoncu, U.S. Geological Survey, USA

Fossil fuel combustion products are inorganic impurities that are left behind upon burning of fossil fuels. Coal, among fossil fuels, contains the largest fraction of such inorganic impurities and accounts for the largest quantities of these materials generated. In the United States, electricity accounts for more than one third of the total energy consumption, and more than half the Nation=s electricity is generated by burning coal. More than 80% of coal mined in the United States is used in electric generation. During 1999, approximately 860 million metric tons (Mt) of coal were burned by the electric utilities and approximately 100 Mt of coal combustion products (CCP=s) were generated. Components of CCP=s are fly ash, bottom ash, and boiler slag. Flue Gas Desulfurization (FGD) material is also included in this category. Over 30% of the CCP=s produced was used in a number of applications. The largest application for a specific CCP was the use of 10.3 Mt of fly ash in cement and concrete. The leading uses of bottom ash include structural fill (1.3 Mt) and road base and sub-base materials (1.0 Mt). Approximately 90% of boiler slag was used in the blasting grit and roofing granule markets, while almost 3 Mt of FGD material was used in wallboard manufacture. The use of CCP=s has increased from 12% of what was generated in 1966, the first year that such statistics were gathered, to 31% in 1999. This translates into five-fold increase in the quantities used. We will have 2000 data available by the time of the conference. RSK 34-3

The United States’ Combustion Byproducts Recycling Consortium,

Paul F. Ziemkiewicz, Tamara Vandivort, West Virginia University, USA

The Combustion Byproducts Recycling Consortium (CBRC) was initiated in the fall of 1998 to provide national focus for development of beneficial uses for the products of coal combustion. CBRC promotes and supports the commercially viable and environmentally sound recycling of coal combustion byproducts for productive uses through scientific research, development, and field testing. The CBRC is funded by the U.S. Department of Energy-National Energy Technology Laboratory (DOE-NETL) and collaborating companies. Over the past two years, $2.6m in USDOE funds have been matched by $3.3m industry dollars in 31 projects.

39

Current projects include: mine filling, structural applications, agricultural soil amendments and construction products. CBRC is managed by the National Mine Land Reclamation Center (NMLRC) at West Virginia University with regional management by Southern Illinois University-Carbondale and the University of North Dakota. Within each region, teams of technical experts from industry and government have developed research priorities and, annually, rank proposals for funding. A national steering committee consisting of senior Federal, State and Industry representatives provides program direction and project selection. The primary goal of the CBRC is to develop and demonstrate technological solutions related to the utilization of byproducts associated with coal combustion processes. It is hoped that by the year 2005, these technologies will lead to a doubling of the current rate of flue gas desulfurization byproduct use, a 10% increase in the overall national rate of byproduct use, and a 25% increase in the number of uses permitted under state regulations. This paper describes how CBRC is organized and managed. It also summarizes our research priorities, projects and early results. 34-4

Coal Mining and Reclamation in the USA with Coal Combustion By-

Products: An Overview

Kimery Vories, USDI Office of Surface Mining, USA

The use and disposal of Coal Combustion By-Products at coal mines in the USA has become an area of intense interest, research, activity, and controversy over the last few years. The U.S. Department of Interior, Office of Surface Mining (OSM) was created in 1977 as part of the Surface Mining Control and Reclamation Act to provide minimum levels of protection concerning public health, safety, and the environment and balance this with the need for a viable U.S. coal supply. Beginning in May of 1994, OSM has taken an active role in encouraging and promoting technological advances, research, and technology transfer related to the use and disposal of those material residues remaining after the combustion of coal to produce electrical power. Currently, there is less than 2 percent of the CCBs that are produced in the U.S. that are placed back at the mine site where they originated. Most of the uses to date have been extensively researched and indicate that the material usually results in a beneficial impact to human health and the environment because it is used primarily to mitigate other existing potential mining hazards. Beneficial uses include: (1) use as a seal to contain acid forming materials and prevent the formation of acid mine drainage; (2) as an agricultural supplement to create productive artificial soils on abandoned mine lands where native soils are not available; (3) as a flowable fill that seals and stabilizes abandoned underground mines to prevent subsidence and the production of acid mine drainage; (4) as a construction material for dams or other earth like materials where such materials are needed as a compact and durable base; and (5) as a non toxic fill for final pits and within the spoil area. Although the recycling of these materials into useful products has attracted a great deal of interest as a raw material for basic construction products, there has also been a growing controversy from environmental groups that consider the use of these materials to place an unacceptable risk on public health and environmental quality. This paper will attempt to provide an overview of how the dynamics of the efforts to increase the recycling and use of these materials and counter efforts to place all of these materials in perpetually sealed and controlled landfills has played out on the microcosm of the coal mining and reclamation community. 34-5

CCB Use in Highway Construction in The United States

Kevin H. Gardner, T. Taylor Eighmy, David L. Gress, Jean C.M. Spear,

University of New Hampshire, Khaled Sobhan, New Mexico State University, Mohsen Kashi, GEI Consultants, USA

This paper will review a number of research projects focused on highway applications of Coal Combustion By-Products that are funded through the Recycled Materials Resource Center (RMRC) at the University of New Hampshire. The RMRC is a partnership with the Federal Highway Administration, and focuses on promoting the wise use of recycled materials in highway environments. This paper will present four projects that involve the use of CCBs in transportation applications. The first project presented consists of a laboratory investigation to evaluate the performance of a cement-stabilized pavement base course material consisting of recycled concrete aggregate, ASTM Class C fly ash, and waste plastic (high-

density poly ethylene) strips obtained from post-consumer water and milk containers. The primary focus of the study was to systematically characterize the new composite base course under both static and dynamic (fatigue) loading conditions to gain some insights into the long-term durability of the material. The study indicates that the new composite base course consisting primarily of waste products holds considerable promise as an alternative material for the construction and rehabilitation of highway pavements. Material and performance data will be presented. The second project presented investigates synthetic lightweight aggregates (SLA) developed from coal fly ash and recycled high-density polyethylene, HDPE. This project’s goals were to evaluate the process for production of SLA using waste plastics and fly ash of various characteristics, and to evaluate the physical, mechanical and chemical characteristics of the developed aggregates. Furthermore, the potential for use of SLA in concrete and geotechnical applications was evaluated. A third project focuses on assessment of the susceptibility of concrete containing Recycled Concrete Aggregate (RCA) to the reoccurrence of Alkali Silicate Reactivity (ASR). Several mitigation strategies using various quantities of fly ash, ground blast furnace slag, and lithium nitrate are being tested under laboratory conditions using RCA obtained from concrete removed from I-95 near Gardner, Maine. The purpose of the mitigation techniques is to prevent ASR from occurring in concrete containing RCA. The fourth project to be presented focuses on environmental characteristics of coal fly ash, particularly on how the leaching of heavy metals changes over time due to chemical weathering of the ash material in the environment. It has been shown that weathering reactions (dissolution, precipitation, crystallization) can have significant impacts on the availability of heavy metals in combustion byproduct materials. Results from accelerated weathering experiments will be presented, and implications for the long-term environmental characterization of fly ash use will be discussed.

SESSION 35

GREENHOUSE GAS CONTROL & CO2 SEQUESTRATION-VI

35-1

Research Status on the Sequestration of Carbon Dioxide by Direct Aqueous Mineral Carbonation

W.K. O’Connor, D.C. Dahlin, D.N Nilsen, S. Gerdemann, G.E. Rush, R.P.

Walters, P.C. Turner, Albany Research Center, USA

Direct mineral carbonation has been investigated as a process to convert gaseous CO2 into a geologically stable, solid final form. The process utilizes a solution of sodium bicarbonate (NaHCO3), sodium chloride (NaCl), and water, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, by diffusion through the surface and gas dispersion within the aqueous phase. The process includes dissolution of the mineral and precipitation of magnesium carbonate (MgCO3) in a single unit operation. Optimum results have been achieved using heat pretreated serpentine feed material, the bicarbonate-bearing solution, and high partial pressure of CO2 (PCO2). Specific conditions include: 155C; PCO2=185 atm; 15% solids. Under these conditions, 78% stoichiometric conversion of the silicate to the carbonate was achieved in 30 minutes. Studies suggest that the mineral dissolution rate is primarily surface controlled, while the carbonate precipitation rate is primarily dependent on the bicarbonate concentration of the slurry. More recent studies suggest that significant carbonation can also be achieved, using the bicarbonate solution, at a much reduced PCO2 of approximately 15 atm. Current and future activities include further examination of the reaction pathways, various pretreatment options, the development of a continuous flow reactor, and an evaluation of the economic feasibility of the process. 35-2

Green Coal thru Ocean Nourishment

Ian S F Jones, L. Amestistova, University of Sydney, AUSTRALIA

By combining a carbon dioxide sink credit with the sale of coal, a new climate friendly commodity can be produced. Ocean Nourishment is a technology that can sequester carbon without needing to capture the carbon dioxide at the site of combustion of the coal. Thus credits for such carbon sinks can be generated before the use of the coal. By providing additional nutrients to the desert regions of the ocean, ocean nourishment can sequester atmospheric carbon dioxide and increase the sustainable fish catch. The present level of photosynthetic activity of the upper

40

ocean is limited by the supply of macro or micro nutrients. The addition of such nutrients have been demonstrated to increase the primary production. These biological processes transport carbon out of the upper ocean into the deep ocean where it is no longer in contact with the atmosphere. Increasing these processes lowers the concentration of carbon dioxide in the surface ocean and this leads to a flux of carbon from the atmosphere to the ocean. When new nutrients are added the carbon storage can be nearly permanent. The costs of sequestering carbon by ocean nourishment are substantially lower than other reasonable sequestration alternatives. The costs are associated with the production of reactive nitrogen and its delivery by pipeline into regions of the ocean with prevailing currents. The present day cost of such sequestration is in the range of US$5-15 per tonne CO2 avoided. The term ‘avoided’ implies a measure equivalent to not emitting one unit of CO2. 35-3

Properties of Novel Carbonic Anhydrases with Application to the

Sequestration of Carbon Dioxide

James G. Ferry, Pennsylvania State University, USA

Carbonic anhydrase is an enzyme which catalyzes the hydration of carbon dioxide to yield the charged bicarbonate anion product. The enzyme has application in the sequestration of carbon dioxide from point sources. Previously, only the enzymes from plants or animals have been available for the development of processes for carbon dioxide sequestration. Our research has focused on the identification and characterization of novel carbonic anhydrases from microbes, particullarly strains from extreme environments that would likely have more robust properties. We recently discovered two novel carbonic anhydrases from thermophilic microbes. Methods for the large-scale production of these enzymes for industrial applications have been devised. The enzyme, Cam, from Methanosarcina thermophila represents a new class (the gamma class) with a novel protein fold and an active site unique from the previously characterized alpha-class carbonic anhydrases from animals and the beta-class from plants. Cam has a high rate of catalysis and a unique mechanism for removal of protons during catalysis. The crystal structure reveals a novel protein fold and amino acids adjacent to the active site zinc that are proposed to function in the catalytic mechanism. The carbonic anhydrase, Cab, from Methanobacterium thermoautotrophicum is thermostable up to 85 C and also has robust activity. The crystal structure of Cab shows a different strategy for ligation of the essential zinc active site and amino acids adjacent to the metal that are proposed to be involved in catalysis. Methods for replacing the active-site residues and other amino acids are in place with the goal of enhancing desired properties of catalysis and enzyme stability. 35-4

CO2 Mitigation Economics for Existing Coal-Fired Power Plants

Dale R. Simbeck, SFA Pacific, Inc., USA

Electric power generation represents one of the largest sources of CO2 emissions. Existing coal-based power plants have the highest CO2 emissions of any power systems yet are the lowest cost electric generators. Retrofit CO2 reduction or recovery of existing coal-based power plants has definite advantages—using the existing site infrastructure, having facilities that are mostly paid-off or amortized, and having high baseline CO2 emissions. However, retrofits also have disadvantages—significant capacity and efficiency losses that require replacement capacity addition, and increased fuel use depending on the choice of CO2 mitigation technology. TransAlta is a major coal-based electric power generator in Canada and the United States. As discussed at www.transalta.com in the Sustainable Development section under “Our Actions,” TransAlta has a goal of zero net greenhouse gas emission (including trading and offsets) for its Canadian operations by 2024. As part of this ambitious goal, TransAlta funded site-specific analysis by engineering vendors of two noteworthy PC retrofit CO2 capture options: flue gas CO2 scrubbing (amine) and oxygen combustion with flue gas recycle. SFA Pacific standardized and summarized these two analyses into single-page evaluation spreadsheets that include mass and energy balances, capital cost buildups, and economics. Additional options are developed in this simplified format for easy comparison on a consistent and transparent basis. This approach facilitates the objective identification of specific situations, innovative options, and R&D opportunities that could significantly improve CO2 reduction, capture, separation, and utilization.

35-5

Biocatalytic Degradation of Coal and Other Environmental Pollutants: Possible Genetic Engineering of a Microbial Super Strain

Nawin C. Mishra, University of South Carolina, USA

The USA has a great reservoir of coal enough to meet its energy requirements for the next 200 years. The use of coal as a major source of energy throughout the world is a primary source of pollution due to the release of NOx and SOx into the environment — particularly the latter, which contributes to the formation of acid rain. In our studies of the catalytic role of enzymes in coal degradation, we have isolated a 42 kdal multi functional protein from the fungus Neurospora crassa that can depolymerize coal and other polymeric substances (such as rubber) and also removes sulfur at source. The protein is being characterized by its various enzymatic activities and its success as a biocatalyst. We plan to clone the Neurospora gene via RT-PCR by obtaining mRNA and then making and amplifying cDNA using the polymerase chain reaction (PCR). A super strain of E. coli or yeast could prove cost effective for large-scale coal degradation carried out at ambient temperature and pressure more easily and less expensively than standard high temperature/high pressure cleaning processes, minimizing the release of NOx and SOx into the environment. Accomplishment of our research in yielding a cleaner and more ecofriendly energy source and possible cost-effective bioremediation of coal and other polymeric material (such as rubber) on site will be discussed. 35-6

Emissions of CO and NOx in a Spouting-Moving Bed Reactor for RDF

Pyrolysis and Combustion

Zhiqi Wang, Zengli Zhao, Haibin Li, Chuangzhi Wu, Yong Chen, Chinese Academy of Sciences, Baoqing Li, State Key Laboratory of Coal Conversion, P.

R. CHINA

The production and accumulation of Municipal solid waste (MSW) have become to important global environmental issues. Combustion, pyrolysis or gasification offers some benefits over conventional landfill: energy can be recovered and the quantity of waste can be reduced greatly. Studies indicated that emission of poisonous gas and heavy metals might be less by pyrolysis or gasification (gas combustion) environment than that of direct combustion. Refused derived fuel (RDF), made from combustible components of MSW, are suitable for pyrolysis or gasification for their some advantages of high heating value, identical density and similar size, easy transportation and removing sulfur and chlorine by adding additives. Spouted bed is a kind of high performance reactor for fluid- coarse solid particles (dp>1mm) reaction. This Technology has been applied to a wide variety of chemical processes such as gasification, combustion and pyrolysis. A spout-fluid bed is a hybrid fluid-solid contacting system in which spouting gas is introduced upwards through a orifice located in the central of the bottom, accompanied by auxiliary gas (fluidizing gas) from surrounding distributor (flat or conical base). Therefore, it has the characteristics of both spouted bed and fluidized bed, and is suitable for handling agglomerating or sticky solids. Study showed that the minimum operation fluid flowrate of spouted bed is less than that of spout-fluid bed. Considering that low oxygen level (less air volume) is expected for pyrolysis or gasification of RDF, a spouted bed is preferred to being selected as the reactor. Moreover, because of the bad flowability of RDF, horizontal auxiliary gas is introduced to improve the movements of RDF particles in the spouted bed, just like spout-fluid bed, but no fluidization in annulus. Thus, we call this kind of reactor "spouting-moving bed". A spouting-moving bed reactor, basing on partial combustion to heating reactor for pyrolysis and gas combustion was designed and developed. The reactor is constituted mainly of two sections. The lower section is spouting-moving bed pyrolyzer section; the upper section is gas combustor. A connector to cascade the upper combustor and the lower pyrolyzer is made up of a truncated 60o cone attached to another 60o inverse truncated cone, where the secondary air is introduced. A model RDF produced in our laboratory was used to evaluate the performance properties of the reactor. The effects of secondary air and temperature in combustor, as well as bed temperature in pyrolyzer on the emissions of CO and NOx in the flue gas were investigated in this paper. The results showed that not only the temperature in combustor and secondary air amounts has effect on the CO emissions but also the bed temperature in pyrolyzer. For lower nitrogen content of RDF, only the temperature of combustor and secondary air have effect on the NOx emissions. In generally, the emissions of CO and NOx in this reactor are relatively lower.

41

SESSION 36 PYROLYSIS AND DIRECT COAL CONVERSION-III

36-1

A Single Particle Reactor for Investigating the Thermoplastic Behaviour of

Australian Coal during Pyrolysis

Jiang-long Yu, Vladimir V Strezov, John A Lucas, Gui-Su Liu, Terry F Wall, University of Newcastle, AUSTRALIA

Char structure has been found to play a significant role in combustion and gasification kinetics and ash formation during conversion. Monitoring individual coal particle behaviours during devolatilisation process is a promising approach for investigating char formation and coal swelling mechanisms, especially under pressurized conditions, for which there is a severe lack of experimental data. In the present work, as a part of project on char formation, a pressurized single particle reactor has been built to investigate pulverized coal pyrolysis in a nitrogen atmosphere. The pressure chamber allows up to 100 bar of ambient pressure. Temperature history is calibrated with thermocouple, and a Platinum plate is used as electrical heating element. An optical video camera has been equipped to record coal particle morphology changes during the pyrolysis process and images are transferred to PC for further analysis. Through image analysis, the transient swelling ratio and surface texture changes are quantitatively determined. To investigate effects of maceral concentration on coal swelling properties, density fraction samples of three Australian coals have been chosen for the present experiments. Heating rate and pressure effects on coal particle behaviour were investigated. The obtained data on swelling behaviour and morphology changes will be used for validation of a transient char evolution model developed by the authors. 36-2

Interactions Between Coals in Binary Blends During Pyrolysis as Studied

by Thermal Rheology, PMRTA, TG-FTIR and Optical Microscopy

J.A. MacPhee, L. Giroux, J.-P. Charland, J.T. Price, CANMET Energy Technology Centre, CANADA, R. Sakurovs, CSIRO Energy Technology,

AUSTRALIA

The Liquid Phase Methanol (LPMEOH) process uses a slurry bubble column reactor to convert coal-derived synthesis (syngas) gas to methanol. The LPMEOH™ process provides the means to convert synthesis gas to methanol at higher per-pass conversion than conventional gas-phase technologies. Because of its superior heat management, the process can directly utilize the carbon monoxide (CO)-rich syngas characteristic of the gasification of coal, petroleum coke, residual oil, wastes, or other hydrocarbon feedstocks. When added to a high-efficiency integrated gasification combined cycle (IGCC) power plant, the LPMEOH process converts a portion of the CO-rich syngas produced by the gasifier to methanol, and the unconverted gas is used to fuel the gas turbine combined-cycle power plant. A 260-short tons per day (STPD) LPMEOH™ Process Demonstration Plant has been in operation at Eastman Chemical Company’s chemicals-from-coal complex in Kingsport, Tennessee since April of 1997 under a Cooperative Agreement with the U. S. Department of Energy (DOE). This demonstration project is part of the DOE’s Clean Coal Technology Program. Production rates of over 300 STPD of methanol have been achieved and the plant availability for the past three years has been 99%. This paper provides a description of the LPMEOH™ process and the application of the technology to IGCC power plants. Under a 15-month extension to the project, additional operating time will provide the opportunity to perform new tests of significant commercial interest (such as the activation of methanol synthesis catalyst in the LPMEOH™ Reactor). A review of the status of these tests and ongoing performance results will be presented. 36-3

Modeling of Coal Pyrolysis By-Products for the Development of Superior

Binder Pitches

John M. Andrésen, Harold H. Schobert, Frank J. Rusinko, Jr., The Pennsylvania State University, USA, Ruth A. Strøm, Norwegian University of Science and

Technology, NORWAY

The outlook for the use of traditional coal tar pitch as binder for carbon materials is indeed very bright based on the current technology. It is estimated that the coal tar pitch market will grow around 3% annually the next four years in US and Europe from 2.5 million tonnes in 2000 to 2.8 million tonnes in 2004. This increase is mainly due to the demand from the aluminum industry accounting for about 75% of the pitch market, although the use of binder pitch

in the carbon and graphite industry is also rising. However, the production of the precursor for coal tar pitches, i.e. coal tar, is rapidly decreasing in US as well as throughout the world, leading to an predicted shortage of binder pitch in 2008 of around 700,000 tons. Hence, the development of superior binders from alternative sources, such as various pyrolysis product streams from coals, can pave the way for a sustainable growth in the carbon artifact market. Accordingly, this study has modeled different coal pyrolysis by-products and compared them with traditional coal tar pitches to identify streams that can be used for the development of superior binder pitches. Modeling of traditional coal tar pitch structures were performed to determine the optimum structure to be achieved during the synthesis of superior binder materials for carbon products from aromatic feedstocks, such as coal derived liquid from pyrolysis. The synthesis of superior binders for carbon materials can be a solution to several shortcomings of binders used today, including the emission of poly-aromatic hydrocarbons (PAHs), dependence on foreign sources and the use of extreme process condition during baking due to high pyrolytic weight loss. Hence, the experiments performed during this reporting period address these aspects and related them to the modeling of traditional coal tar pitches and their fraction, particularly the toluene soluble (TS) and the b-resin fractions. Firstly, the evolution of different PAHs during the pyrolysis of the whole pitch was identified by pyrolysis gas chromatography and mass spectroscopy (py-GC/MS). Further, the low molecular species as well as the oligomeric networks in pitch fractions were identified by laser desorption mass spectroscopy (LD/MS). The information from these two complementary MS techniques were interlaced with findings from solid state 13C NMR, elemental analysis and X-ray diffraction. The structural data about the building blocks for traditional coal tar pitch fractions were used to generate overall structural models of the TS and the b-resin fractions using modeling software. The structures modeled will be used as a visualization tool for the synthesis of binders from untraditional coal pyrolysis by-products 36-4

Product Analysis of Catalytic Multi-Stage Hydropyrolysis of Lignite

Wen Li, Na Wang, Baoqing Li, State Key Laboratory of Coal Conversion, P. R.

CHINA

A lignite added with 0.2% MoS2 as catalyst was pyrolyzed under H2 using multi-stage heating method (MHyPy), i.e., holding a suitable time near the peak temperatures based on the TG behaviour. The product distribution and detailed analysis of products were performed. The results show that the tar yield increased to 63.9% during MHyPy compared with that of 51.8% in traditional hydropyrolysis (HyPy), while the gas yield decrease half. This suggests the effective utilization of hydrogen during MHyPy. The light aromatics in the tar from MHyPy remarkably increased 42%, 37.8% and 115.4% for BTX, PCX and naphthalenes respectively. Biphenyls were also observed in the tar from MHyPy, indicating that the effective hydrogenation occurs during catalytic MHyPy. The rich pore structure of the char from MHyPy hints its high reactivity in the subsequent conversion process such as gasification and combustion. 36-5

An Investigation into the Thermal Events During Pyrolysis of Coal/Biomass

Blends

H.B. Vuthaluru, J. Opje, D.K. Zhang, Curtin University of Technology, AUSTRALIA

An investigation into the thermal events occurring during pyrolysis of coal/biomass blends prepared at different ratios (0/100, 10/90, 20/80, 30/70, 50/50 and 100/0) have been performed using thermogravimetric analysis (TGA) apparatus. Coal sample selected was Collie from Western Australia, while the wood waste and wheat straw were used as biomass samples. Three thermal events were identified during the pyrolysis. The first two were dominated by the biomass pyrolysis, while the third was linked to the coal pyrolysis, which occurred at a higher temperature. Some interaction was seen between the biomass and coal during pyrolysis. The addition of wood waste to the coal led to a lowering of the thermal degradation temperature of the coal, while the addition of the coal to the wheat straw increased the thermal degradation temperature of the wheat straw. It was found that the optimum blend ratio for pyrolysis is 50% with a high reaction rate in all thermal events and a higher mass loss over the course of the pyrolysis than other wood waste/coal ratios examined. The reaction orders in these experiments were found to be in the range of 0.21-1.60, thus having a marked effect on the overall reaction rate. Besides the pyrolysis of pure coal, the 50/50 wood waste coal pyrolysis had the highest reaction rate, at 2.10E+09 s-1. When the order of reaction was assumed to be unity, ideal wood waste/coal ratio was found to be 20:80 for coal pyrolysis, which showed the lowest activation energy of 90.9 kJ.mol-1.s-1.

42

SESSION 37 COAL PRODUCTION AND PREPARATION-III

37-1

Factors Contributing to Sticky Coals During Wagon Unloading for Queensland COALS

Graham O’Brien, Mike O’Brien, Bruce Firth, D. Nemeth, CSIRO Energy Technology, J. Graham, Queensland Rail, Rollingstoc k Engineering, S.

Gnanananthaan, Queensland Rail Coal and Freight Services, AUSTRALIA

A large number of the coals exported from Queensland, Australia present a handling problem to Queensland Rail (QR) and the Ports. QR and the major ports have identified the problem of “sticky “ coals as a significant cause of loss of productivity. “Sticky” coals are those that do not flow freely from rail wagons during the unloading operation. Unloading delays vary from half-an-hour to six hours and with over 40 trains a day on the corridor, even short delays regularly cause consequential delays to following trains and reduce the capacity of both the ports and the rail system. A collaborative investigation to identify the factors that cause this “stickiness” was undertaken by CSIRO and QR. Fieldwork was conducted at central Queensland coal mines to quantify the consolidation forces imparted by different loading methods and during the rail journeys to the port. Testing was done at the ports to determine the amount and location of the consolidation in different wagon types and different mine products. Load cells were placed in test wagons to determine loading forces and an accelerometer was used to establish the frequency and amplitude of the travel forces. An ultrasonic device was used to position this consolidation with the wagons. Consolidation of material resulting in arching over the door openings. These arches can be stable up to about 500mm above the tie bar or centre sill running through the central bottom region of the wagons and coal cannot flow through that door set until the arch is broken. The amount of consolidation obtained was also influenced by the physical coal characteristics (moisture content, size distribution, amount of fine clay) and wagon geometry. When the problem occurs, jackhammers are employed to vibrate the side of the wagons to promote flow of the coal. The degree of effort can vary from a minimal amount of inducement with little increase in the time required to unload the train to a doubling of the time of unloading. The information obtained from these field trials was used to design a comprehensive series of laboratory and pilot scale experiments and field trials aimed at improving discharge of ‘sticky’ coal. These tests will investigate: ·Better methods for applying vibration, or other types of force. ·Incremental changes to the interior geometry of the wagons to minimise arch formation of the consolidated coal. ·Changing the loading method to reduce consolidation. Improvements in the unloading of trains will provide opportunities for both QR and the ports to reduce operating costs and defer capital investment both of which present opportunities to reduce costs and hence charges to the coal mines. Collaborative research provides the best chance for finding a practical solution that will benefit all the participants in the coal export chain. 37-2

Coarse Coal Flotation

Noel W A Lambert, Graeme J Jameson, University of Newcastle, AUSTRALIA

A new technique to process 0.5 to 2mm coal has been developed at the Centre for Multiphase Processes, University of Newcastle. Current equipment (spirals, TBS, lower sized end of dense medium cyclone feed) produces a higher than optimum product ash. This in turn lowers the potential plant yield due to the need to run other circuits at less than optimum output to maintain product specification. The new process involves splitting the feed at approximately 0.5mm, using the 0-0.5mm material to form a stable froth in a flotation cell and then adding the 0.5 to 2mm material with the wash-water directly into the froth. This system overcomes the size limitation of normal flotation, which is that particles generally larger than 0.5mm cannot be carried out of the slurry phase. In 0.25 tph pilot scale tests, a 7% product concentrate has been produced from 25% ash feed, producing a tailings ash of 86%, with a mass yield of 86% and a combustible yield of 96% for a 0 to 1.7mm feed. Yields were similar across all size ranges.

This can have the potential to increase total plant mass yield by 5 percentage points or more without changing the product specification. A 9tph demonstration plant (sponsored by the Australian coal industry through ACARP) is currently under construction. 37-3

A Study on the Beneficiation of Asphaltite

Güven Önal, S. Girgin, Istanbul Technical University, TURKEY

In Southeastern part of Anatolia, petroleum based asphaltic materials close to Sırnak Province are placed within an area of 17000 km2 . This study comprises the technological tests for the beneficiation of Sırnak asphaltites. Experimental tests were conducted on the asphaltite sample with ash, sulphur, volatile matter, and fixed carbon contents of %43.8, %13.3, %34.8, and %21.2, respectively. Also the calorific value of representetive sample was found to be 4938 kcal/kg. Qualitative XRF determinations showed that the major inorganic material forming elements are Fe, Ca, and Mo where pyrite, calcite, and molybdenum sulphide formations are expected. Technological tests covered physical and physico-chemical separation methods such as super panner separation, multi-gravity separation, and flotation. Gravity concentration tests gave no satisfactory results in terms of ash removal. Technological tests were detailed with flotation experiments at various flotation conditions. The most significant observation during flotation tests found to be the flotation ability of asphaltite without using any collector or frother. It is determined from the results that, decreasing the content of ash forming materials down to 15% level is related mainly with particle size and the number of cleaning stages of flotation circuit. Also the decreasing the bubble strength is of great importance in terms of preventing the ash forming materials to float. 37-4

Study on Production of HyperCoal (Ashless Coal) by Using Organic Solvent

Extraction: Characterization of HyperCoal and Mechanism of Thermal Extraction

Toshimasa Takanohashi, Takahiro Yoshida, Kinya Sakanishi, Ikuo Saito,

National Institute of Advanced Industrial Science and Technology, Masaharu Fujita, Kiyoshi Mashimo, Nihon University, JAPAN

HyperCoal (ashless coal) leads to innovative use for gas turbine combined power generation system with quite high efficiency and lower emission of CO2. Thermal extraction of coal using various organic solvents under mild conditions (below 400BC, low pressure inert gas atmosphere) is one of the most effective methods for the selective extraction of organic part in coal without any chemical reactions. We name such an ashless coal HyperCoal hereinafter. The effects of coal and solvent types, and extraction temperatures on the extraction yield (HyperCoal yield) and ash content in HyperCoal were investigated. When thermal extraction was carried out at 360$B!k(BC with DMN solvent, around 70 % of extraction yield was achieved for Upper Freeport and Illinois No.6 coals. In case of light cycle oil (LCO) as a solvent used, over 50 % of extraction yield was obtained for Illinois No.6 coal, showing that LCO can be a potential extraction solvent because of its low cost and availability in the HyperCoal production. Characteristics of HyperCoal are presented based on their structural analyses by FT-IR and solid-state NMR, and finally the mechanism of the thermal extraction is discussed. 37-5

The Study of Digital Froth Image Processing and its Recognition

Fan Wang, Maixi Lu, Yong Wang, Wenli Liu, CUMT, P. R. CHINA

Computerized digital froth image processing was becoming more and more attractive when computer vision was applied to flotation controlling field firstly. This paper gave a description of computerized digital froth image processing and its pattern recognition, which covered the fields of image equalization, edge detection, edge closing, thinning, textural feature extraction and discrete statistic pattern classification. The study also presented a set of software developed by Beijing Campus of China University of Mining and Technology. By means of it, a series of textural features as of spatial gray level co-occurrence matrix, neighboring gray level dependence matrix and gray level run length matrix were acquired, the distribution of bubbles in size and shape were also extracted.

43

In this paper, a set of artificial neural network was designed to classify all the froth image textural features imputed. Through self-organizing feature map, all froth images were classified into 4 classes.

SESSION 38

GASIFICATION OF COAL

38-1

Numerical Modelling of Underground Coal Gasification and its Application to Australian Coal Seam Conditions

G. Perkins, V. Sahajwalla, University of New South Wales, A. Saghafi, CSIRO

Division of Energy Technology, AUSTRALIA

In the last 5 years there has been an increasing interest in the Australian energy and mining industry for the development of new operating underground coal gasification (UCG) systems to generate synthetic gas from coal seams underground. A pilot burn in a shallow coal seam in southern Queensland has been operating since early 2000. In Australia the UCG gas will be initially used as a competitive fuel for power generation followed by use as a feedstock for the petro-chemical industry. In line with these renewed UCG activities, CSIRO Energy Technology and the University of NSW undertook to develop a numerical model of UCG process aimed at simulating the physico-chemical process of underground gasification together with full modelling of cavity formation and its growth due to collapse of the strata and pulverisation of overburden material under the effect of chemical conversion, heat and gravity. The numerical model is formulated using a two phase Eulerian approach. It includes coupled thermal, fluid flow and chemical reaction processes, which occur at the cavity boundary within the coal seam. The model is being validated against laboratory measurements of coal consumption under oxidizing conditions. The model outputs are also being compared to the actual data from two previous field trials in USA. So far the comparisons of the model results with actual coal consumption data at the laboratory show acceptable agreement. It is aimed to apply the model to simulate the cavity evolution and gas production from the UCG operation in Australian coal seam conditions. 38-2

Simulation Study for the Comparisons of the Performance and the NOx Emission Characteristics of Integrated Gasification Combined Cycle Power

Plants Using Coal or Heavy Residue Oil

Chan Lee, Je Young Seo, Suwon University, Seung Jong Lee, Yongseung Yun, Institute for Advanced Engineering, KOREA

Thermodynamic and chemical process simulation method is developed to analyze the performance and the NOx emission characteristics of the power block of IGCC(Integrated Gasification Combined Cycle) coupled with ASU(Air Separation Unit). Chemical processes, Shell-based coal/heavy residue oil gasification and cold gas clean-up, are modeled by using ASPEN Plus code, and the simulation results are favorably compared with actual test results. Based on the clean coal gas fuel conditions predicted from the chemical process simulation, the thermodynamic analysis of combined cycle of IGCC is carried out by the GateCycle code. The present combined cycle model contains thermodynamic computation scheme as well as the compressor performance map and the expander choking models which can be used to consider the off-design effects due to coal gas firing and ASU integration. In addition, the present simulation method employs a NOx emission prediction model with the use of semi-analytical approach. With two kinds of feedstocks such as Datong bituminous coal and visbreaker residue, the present study investigates and compares the overall performance and the NOx emission characteristics of IGCC plants at various ASU integration conditions in terms of air extraction ratio and nitrogen dilution. The reduction of air extraction ratio and the employment of nitrogen dilution result in the increase of plant power, and the power of IGCC plant with visbreker residue is somewhat less than that with datong coal . The efficiency of IGCC power block is optimal at 20% without nitrogen dilution while at 40-60% with nitrogen dilution. When the IGCC power block is designed with nitrogen dilution and at higher air extraction ratio, the present prediction shows narrower surge margin of IGCC gas turbine which can cause operation instability of power plant. Applying nitrogen dilution reduces the NOx emission level of IGCC down to the 60 percent of that without nitrogen dilution, but the air extraction ratio has minor effect in reducing NOx emission.

38-3 Coal Gasification and Ash Formation at High Pressures and Temperatures

Terry F. Wall, Gui-su Liu, Hongwei Wu, Kathy Benfell, John Lucas, Daniel

Roberts, David Harris, John A. Lucas, CRC for Coal in Sustainable Development, AUSTRALIA

Advanced clean coal technologies, i.e. integrated gasification combined cycle (IGCC) and pressurised fluidised bed combustor (PFBC), have gain increasing technological and scientific interests over the last a few decades. Pressures up to 40 atm have been applied to these technologies, which inherently result in an increase in coal throughput, a reduction in pollutant emission and an enhancement in the intensity of reaction. Therefore fundamental understanding of the effect of operating pressure on coal reactions is essential to the development of these technologies. In this paper, the pressure effect on a variety of aspects of coal reactions reported in open literature, as well as the significant advances achieved in Coopoerative Research Centre (CRC) for Black Coal Utilisation in Australia, has been reviewed. The pressure has been found to significantly influence the volatile yield and coal swelling during devolatilisation, hence the structure and morphology of the char generated. More char particles of high porosity are formed at higher pressures. Char structure appears to play a significant role in burnout of residual char and ash formation, with a significant effect of pressure. In general, at higher pressures, coal particles burn quicker and form finer ash particles. Increasing reactant pressure enhances char combustion and gasification reaction rate, which can be understood by an adsorption-desorption mechanism. These have been applied to the understanding of a practical high-pressure gasifier. 38-4

Heterogeneity of Slags From Entrained Flow Gasifiers

Gregory J. Browning, Daniel Roberts, John A.Lucas, Terry F. Wall, CRC for

Coal in Sustainable Development, AUSTRALIA, Masami Ashizawa, Yuso Oki, Yokosuka Research Laboratory, JAPAN

The accepted criterion for the adequate removal of slag from entrained flow coal fired gasifiers is the slag viscosity. Viscosity measurements of homogeneous (fully liquid) slags from coal ash prepared in the laboratory, are being used to establish the suitability of particular coals for the technology, and the necessity for adding flux during firing to lower viscosity. To assess the applicability of using viscosity data from these homogenous slags in a practical situation, slag samples from pilot scale gasifiers were examined under scanning electron microscope where a number of sources of heterogeneity were identified. The aim of this paper is to highlight some of the issues associated with the direct application of laboratory viscosity data and thermodynamic predictions to the estimation of slag viscosity in a practical situation. 38-5

Characterization of Cenosphere Formed in High-Pressure Pyrolysis

Akira Tomita, Hiroyuki Akiho, Koichi Matsuoka, Tohoku University, JAPAN

Cenosphere, balloon-type char with thin wall and large porosity, is often observed in the unburnt char after coal combustion. However, an interest so far has been limited to the morphological observation by optical microscope. The reaction conditions for its formation as well as its characteristics are not fully understood yet. In this paper, we examined the formation of cenosphere upon the high-pressure pyrolysis of six coals in He or H

2, the temperature range being from 600 to 850

°C. It was observed that higher pressure and inert atmosphere were favorable for cenosphere formation, while there was no clear dependence on coal rank and maceral content. The apparent density of cenosphere ranged from 0.04 to 0.07 g/cm3, which is around 1/3 – 1/6 of those of dense char obtained from the same parent coal under the same condition. The fraction of cenosphere char on the weight basis was less than 2 %, but due to the low density the fraction on the volume basis was rather large. The particle size of cenosphere was between 250 and 500 mm, while that of dense char was close to the size of original coal particles, that is 75 – 150 mm. The shape and elemental components were analyzed by SEM/EDAX. The component of the skin structure was mainly carbon with little mineral matter. It is noteworthy that inorganic components were still very little even after a char conversion of 90 %.

44

After separating cenosphere and dense char prepared from Shenmu coal by sieving, their gasification reactivity was compared. The gasification was carried out in a thermobalance at 900 °C under CO

2 of 0.1 MPa. The initial reactivity

was similar to each other, but in the later stage remarkable rate retardation was observed with cenosphere char. Network skeleton portion of cenosphere is likely less reactive than thin film portion. This is the first attempt, to our best knowledge, that determined the reactivity of isolated cenosphere particles.

SESSION 39

SYNTHESIS GAS CLEANING-II

39-1 Cryogenic Air Separation – A Safe and Reliable Supply for Large Oxygen

Capacities

Gerhard Beysel, Linde AG, Carl-von-Linde, Linde AG, GERMANY

The possibility to utilize coal also in the future as a feed for power plants and chemical applications has been extensively investigated during the last years by governmental and private institutions. A very big effort was necessary to develop and test new advanced technologies to make coal clean enough. However to make coal really fit enough for the future, the technologies used have to be reliable, safe and economic enough and can only be accepted on a long term basis if no government or private subsidation is required. “To be only environmental friendly is not enough to survive.“ The gasification of coal in an Integrated Gasification Combined Cycle (IGCC) or other gasification processes need large amounts of Oxygen to be produced in state of the art cryogenic Air Separation Units (ASU‘s). To increase their economic competitiveness, future IGCC’s will not only use advanced Gas Turbines but also require Oxygen Plants with larger capacities. Single train seizes will exceed 3500 metric tonnes per day (MTPD). Other new gasification processess (e.g. Gas to Liquid) will require even larger quantities of Oxygen and a total capacity of more than 14000 MTPD may not be unusual. Within an IGCC the ASU related cost are in the range of 10 % and the portion of internally consumed power can reach 90 %. A Modular design and prefabrication have to be considered to bring the construction and erection cost down. The right choice of process and machinery concepts have another big influence on cost but also on the specific energy consumption. To minimize operation risks during all conceivable operating modes, at all GT/extract air conditions i.e. especially at integrated units, destillation instabilities have to be avoided and the lowest possible complexity shall be selected. While surplus Oxygen can be made available for other process units (e.g. S-recovery) and its purity shall allow the extraction of pure Hydrogen as a by-product from the syngas if required, the Nitrogen will be used to delute the fuel gas and suppress NOx production. The selection of a proven ASU design may also bring down duration and cost of project development – still a too big portion of the total IGCC cost. 39-2

Advances in Oxygen Transport Membrane Technology for Integrated

Oxygen Production in IGCC

Ravi Prasad, Jack Chen, Bart van Hassel, John Sirman, James White, Praxair Inc., USA

The cost of electricity produced by IGCC cycles depends significantly on the cost of oxygen used for gasification. In partnership with the National Energy Technology Laboratory (NETL) of DOE, a team led by Praxair is developing advanced Oxygen Transport Membranes (OTM), which can be integrated with IGCC power generation cycles to produce a step change in the supply of oxygen for gasification. OTM technology is based on ceramic mixed conductor membranes that operate at high temperatures and can be operated in a pressure driven mode to separate oxygen with infinite selectivity and high flux. This paper will provide an overview of the OTM development program, and discuss the progress made in Phase1 to date. It will discuss preferred schemes for OTM integration with IGCC and illustrate the advantages of OTM over conventional oxygen production technologies. Advances in materials selection,

membrane fabrication, element performance, seal technology and reactor engineering will be reviewed. Results to date confirm the potential of OTM to lower capital cost, improve power cycle efficiency, and reduce emissions.

SESSION 40

COAL COMBUSTION BYPRODUCTS UTILIZATION-II

40-1

The Eraring Ash Utilisation Success Story

Peter Heeley, Pacific Power International, Ross Shirtley, Eraring Energy, AUSTRALIA

Eraring Power Station in NSW is one of the largest power stations in Australia (2640Mwe). It consumes over 5 million tonnes of low sulphur sub-bituminous coal per year, with an average ash content of 23%. The resultant 1.15 million tonnes of ash produced, requires a pro-active approach to byproduct utilisation. Eraring’s ash utilisation programme is the largest of any power station in Australia, resulting in the commercial use of approximately 500,000 tonnes of fly and furnace ash every year. In addition, some 2,500 tonnes of cenospheres are being sold per year. The principal use for the fly ash is as a cement replacement in pre-mixed concrete, while the furnace ash is used in a diverse range of applications notably as a substitute for natural fill materials. The development of Eraring’s ash utilisation programme is discussed, with reference to the applications, a range of landmark projects and research and development work. The growth in utilisation rates over the 15 years since commencement is discussed. The requirement for applications to provide a commercial benefit to the end user is discussed, as is the fact that there is no subsidy from the power station to encourage uneconomic uses. A description of the known uses of fly ash and furnace ash and cenospheres from Eraring reveals the diversity of applications. Potential future uses are also discussed. 40-2

Fly Ash Enhances Concrete Resistance to Sulphate Attack

Liana Bucea, Trinh Cao, CSIRO, AUSTRALIA

Many natural and industrial waters contain sulfate ions in concentration that can be deleterious to concrete on long term exposure. The prevention of sulfate attack on concrete consists of selection of appropriate materials and the control of concrete quality. The paper presents a brief review of the mechanism involved in sulfate attack and its importance for designing durable concrete exposed to sulfate soils and sulfate bearing water. The focus of the paper is on the behaviour of fly ash and the benefit of using fly ash concrete in sulfate environment. Some data obtained from the research work at the CSIRO on sulfate resistance of concrete are given. The findings indicate that that sulfate resistance of materials is dependent on the chemistry of the environment and the hardened compounds produced during curing process. The results show that fly ash blended cements has the highest probability of extending the durability of concrete in sulfate containing environment. There are important data that can be used in formulation of better specification and testing methods for material selection and for combating sulfate attack. 40-3

Research and Development for Fly Ash: Opportunity or Alchemy

Jason Nairn, Michael Wilson, Darryl Blackburn, QCL Group, AUSTRALIA

Fly Ash is produced as a by-product of the burning of fossil fuels for power generation. Pozzolanic Enterprises has been extracting, processing and marketing fly ash since the 1960’s. Pozzolanic Enterprises business is all forms of ash disposal, related power station services, and the provision of specialised powder transport services. Pozzolanic has ash removal contracts with four power stations in Queensland, namely: Swanbank; Tarong; Gladstone; and Callide B. The main market for fly ash in Queensland is the concrete industry where it is used to augment cement as a supplementary cementitious material (SCM). Over 90% of all concrete produced in Queensland contains fly ash supplied by Pozzolanic Enterprises. The total amount of fly ash produced by the four power stations is larger than can be consumed by the concrete market thus research and development is being undertaken by Pozzolanic Enterprises to increase the overall utilisation rate.

45

Research and Development will lead to the development of new ash products which will create extra revenue, increase the utilisation of ash and result in a competitive advantage for tendering of power station contracts by improving the service offered to the electrical power generation industry. Fly Ash can be regarded as a low cost natural resource or industrial mineral. It is mainly composed of four materials: alumino-silicate spheres; cenospheres; iron bearing particles; and unburned carbon. A number of materials with different characteristics (eg. particle size, chemical composition, density) can be extracted from the bulk Fly Ash. Fly Ash has the following natural advantages as a raw material: Pozzolanic Nature (cement replacement); Chemical Composition (SiO2, Al2O3, Fe2O3); Size Range (fillers); Consistency of composition from any given source; and Abundant reserves. Fly Ash can be used in a large number of industries and many of these uses take advantage of a combination of the natural properties of the Fly Ash resource. Fly Ash can be used to replace a currently available material (eg. mineral fillers) or as a raw material to produce a new product (eg. Fly Ash bricks). R&D projects can help in both established and new markets. In established markets R&D can improve the customer's knowledge of the value of ash in his/her application. In developing new markets R&D plays the major role in identifying and developing new applications, verifying them through lab work and pilot plant testing, and providing background knowledge for scale-up. The company is committed to R&D to increase its core business activity of "Fly Ash Utilisation". This commitment can be seen in the success of recently completed R&D projects and the establishment of an environment to support further work. Pozzolanic Enterprises has experienced great success with a number of R&D projects being completed and becoming commercial processes or products. This paper outlines some of the major projects (in a range of areas) that have been undertaken by the Pozzolanic R&D department and have reached a significant stage of development. 40-4

Changes in the Chemistry of Combustion Ash with Aging and its Relation

to Stored Ammonia

Aurora M. Rubel, John M. Stencel, Robert Rathbone, University of Kentucky, CAER, USA

The effect of aging, or the time between combustion ash generation and its characterization, on ammonia captured in two ashes was followed using chemical and physical characterization methods. The two ashes, one generated in a utility employing SCR and the other generated in a utility employing SNCR, had original ammonia concentrations of 80 ppm and 338 ppm, respectively. Upon shipment to our laboratory, each ash was sequestered into two fractions. One was placed in a container allowing continuous exposure to air. The other was placed in a hermetically sealed container. Aliquots of each ash were extracted and subjected to CHNS, LOI, ICP, IR and TG/MS analyses. The form of the ammonia contained on the two ashes and the effect of aging were distinct. They were also dependent on whether the ashes had been stored under atmospheric or sealed conditions. For example, the ammonia evolution temperature for the SCR ash started at 355oC and decreased with atmospheric exposure; oppositely, the ammonia evolution temperature for the SNCR ash started at 302oC but did not decrease with atmospheric exposure times. Sulfur dioxide was observed coincident with ammonia evolution. This co-production suggested that ammonia and sulfur compounds were associated with each other when the ashes were generated. In the SCR ash, increased exposure to atmospheric conditions changed the sulfur-ammonia compound association; however, such association did not change in the SNCR ash. Furthermore, the coincident evolution of carbon dioxide with ammonia from the SNCR suggested an association between unburned carbon and ammonia; this association was not observed for the SCR ash. The other characterization data also provided important complementary information to these TG/MS data. Importantly, an accurate depiction of the chemistry of ammonia on combustion ashes has to take into account ash aging effects. 40-5

Predicting Future Behavior of Recycled Materials Used in Highway Applications: Coal Fly Ash Use in Portland Cement Concrete Pavement

Slabs as a Basis for an Accelerated Aging Method

Kevin Gardner, T. Taylor Eighmy, Raymond A. Cook, David L.Gress, Anthony C. Coviello, Jean C.M. Spear, University of New Hampshire, Kenneth Hover,

Susannah Hobbs, Roberto Pinto, Cornell University, David S. Kosson, Florence Sanchez, Vanderbilt University, Charles Kohonen, U.S. Army Corps of

Engineers, Marcia Simon, Turner-Fairbank Highway Research Ctr, USA

Future behavior of recycled materials in highway applications is often difficult to predict. Accelerated aging is one means of exploring the long-term physical and environmental performance. Coal fly ash (CFA) as a cementitious replacement in portland cement concrete (PCC) pavement slabs was selected as a model system for which to develop an accelerated aging approach. Three types of accelerated aging were chosen and applied in an experimental design: Arrhenius aging (AA), cyclic loading (CL), and freeze-thaw exposure (FT). To conduct this study, a field verification site was needed to provide both a mix design to create laboratory prisms for accelerated aging and a distressed field-aged specimen with which to compare them. U.S. 20 in northwest Iowa was selected, this pavement, constructed in 1987, experienced early distress. Numerous early distress or failure mechanisms have been hypothesized, including low initial air contents, high alkali contents in the mixes, alkali silica reaction, freeze-thaw damage, and/or the appearance of ettringite (Ca6Al2(SO4)3(OH)1226H2O) in air voids. The laboratory prisms were made with the same components used in the U.S. 20 job mix in 1987 using the same job mix formulation. A variety of physical and environmental response variables were used to examine the U.S. 20 pavement slab and the aged laboratory prisms. For physical testing, these included compressive strength, microcracking, relative dynamic modulus, porosity, effective pore size, and effective surface area. For environmental testing, response variables included total elemental composition, mineralogy, acid neutralizing capacity, low liquid-to-solid ratio (LS) leaching, pH-dependent leaching, pH-stat leaching, geochemical modeling of controlling solids, availability leaching, and monolithic diffusional leaching. A high degree of potential interaction between the physical and environmental methods was expected. The aging protocol impacted both physical and chemical properties of the monoliths. Generally speaking, the main effects were more important than the interactive effects, which was unexpected. It took about 9 months of elapsed time to age specimens to an equivalent age of up to 4 years. The equivalent ages matched well with the time frame seen in the field for the onset of early distress and also matched well the chronological age of the field pavement. AA significantly reduced the compressive strength of the concrete, possibly indicating the onset of a deleterious reaction in the mix. CL affected the microcracking in the concrete. All aging variables affected the fine pore structure of the concrete. CL affected the Ca diffusional leaching from the monoliths. Logically, there appears to be a linkage between strength loss, microcracking, and leaching behavior of Ca. Most response variables for the aged laboratory prisms and the field samples were similar, suggesting that the aging method did a reasonable job of producing a pavement of similar age and distress. Certain field aging phenomena (more extensive microcracking from unknown sources, road salting, and carbonation) could not be recreated in the laboratory specimens. The AA treatment produced an unexpected loss of strength that suggests the accelerated aging promoted the onset of a deleterious reaction. The use of both physical and environmental response variables shows the linkage between such variables as compressive strength, microcracking, fine pore structure, Cl diffusive leaching (an efflux related to road salting that increases the concentration of Cl in the monolith) and Ca diffusive leaching (related to change in matrix structure and loss of Ca). The use of CFA as a model recycled material in a portland cement matrix was only partially useful in exploring the interaction of physical and environmental performance: The trace metal content and contaminants of concern were present in similar concentrations in the CFA, portland cement, and the aggregates. These constituents leached at very low levels. It was impossible to describe which source term contributed to the low signals that were measured.

SESSION 41

MATERIALS, INSTRUMENTATION AND CONTROLS FOR COAL

41-1

Coal and Carbon Nano-Materials: A Review

Jiang-long Yu, John A Lucas, Vladimir V Strezov, Terry F Wall, University of

Newcastle, AUSTRALIA

Apart from tetrahedra of diamond and stacked planes graphite structures, carbon may exist in the forms of fullerenes (C60 and its relatives) and nano-tubes, which have many unique properties and can be applied in a number of fields such as advanced materials, electronics, environmental clean-up, catalysis etc. Coal, because of its unique chemical structure, has been proven to be an effective and cheap source of bulk production of carbon nano-materials including those based on fullerenes and nano-tubes. In the present paper, production and characterisation of fullerenes and nano-tubes derived from coals have been reviewed.

46

Although it has been reported that fullerenes can be found under natural geological conditions, coal derived fullerenes and nano-tube are usually generated using either plasma arc or thermal activation, using different coals or coal tars. Fullerenes may also be formed under combustion conditions co-existing with soots. Production is characterised using a number of techniques, e.g. XRD, FTIR, GC, HRTEM, etc. Recent studies on new iron-making technologies have identified a potential approach of producing metal-carbon nano-materials through thermal activation performance. 41-2

Observation of Fouling in a Coal Fired Boiler

Peter Moser, Wolfgang Moll, RWE Power AG, Essen, GERMANY

The brown coal fired power plants at RWE are delivered from RWE owned opencast mining. The supplied coal has a varying composition with a trend of increasing heating values and higher amounts of alkali metals and iron. In consequence kind, behaviour and quantity of fouling has also changed. The boiler was equipped with online observation video systems and a steam generator diagnostic system. The diagnostic system depicts boilers by means of thermodynamic balances and determines the fouling of each heating surface online by means of recalculating the heat balances on the flue gas and the water/steam side. Heating surface valuation factors and digital pictures are essentially necessary to observe the status and rate of fouling in the boiler. In the first phase of the project the fouling during operation of different coal qualities was observed by analytically measures. In the second phase rate of fouling and the interference with operation parameters was analyzed by software tools on basis of neuronal networks. With this tool setpoints were developed, which grant an operation with less fouling and also maintain emission limits and increase efficiency. The recommended set points were put into operation during a test period on a 600 MW boiler. The results of this test will be presented. 41-3

Development of Pt-Membrane for Self-Humidification PEMFC

Han-Kyu Lee, Jae-Il Kim, Jin Uk Heo, Tae Hee Lee, Chang-Soo Kim, Yonsei

University, KOREA

In the PEMFC (Polymer Electrolyte Membrane Fuel Cell), water management in electrolytes is one of the complicated problems to be overcome. So far, water content in PEMs has been managed indirectly by humidifying reactant gas. External humidification of the reactant gas is a burden for the fuel cell system. It requires a gas humidification subsystem that adds to the weight. In state-of-the-art commercial stacks with stack integrated gas humidification systems (DeNora, Italy, 5 kW stack and Ballard Power Systems, Canada, 5kW stacks), the humidification section accounts for about 20% of the stack weight. Furthermore, the humidified reactant gas transports latent heat caused by water vaporization into the cell, which has to be removed by the cooling system. Therefore, this method makes the system complicate and lower the cell's energy efficiency because of the large latent heat. This also has difficulty responding to a quick start-up due to a large heat capacity of water reservoir. In this study, we examined characteristics of self-humidifying PEMFC with different methods of Pt-membrane. By recombining the crossover of H2 with O2, the water was generated on dispersed Pt particles in Nafion membrane. The generated water can fully hydrate the membrane, resulting in stable operation of PEFCs without any external humidification. We manufacture three different reformed Pt-membranes, first by cycling the membrane between the reduction agent and Pt solution, second by dipping it in reduction agent after Pt ions are equilibrium in it, and third by sol-gel method. We changed the reaction time both at cycling and dipping and the cell temperature for proper operating conditions (Fig. 1). Uniform dispersion of Pt particles inside membrane is a significant factor in the performance of self-humidification PEMFC. Well dispersed Pt-membrane has better performance because water is formed uniformly in the membrane. Fig. 2 shows Pt particles well dispersed in Nafion membrane 41-4

Development and Commercial Evaluation of LIBS Chemical Analysis

Technology in the Coal Power Generation Industry

Doug Body, Bruce L. Chadwick, The Cooperative Research Centre for Clean Power From Lignite, AUSTRALIA

An instrumentation variation on laser induced breakdown spectroscopy (LIBS) has been developed and applied in the operations of power generating companies utilising low-ash lignite as the fuel source. The instrument design

allows simultaneous determination of all detectable elements using a multiple spectrograph and synchronized, multiple CCD spectral acquisition system. The application of internal ratio analysis has enabled the development of a stable system that can be operated routinely for over a month without re-calibration. Detection limits vary depending on the element but are typically of the order of 0.01 % by weight for elements such as Na, K, Mg, Al, Ca, Si, and Fe in heterogeneous materials such as the moist lignite used in these power stations. Independent testing of the instrument has shown good correlation between the routine LIBS analysis and the analysis of the coal via acid extraction techniques for key ash-forming elements. Testing of over a one month period shows excellent correlation between the two methods for elements such as Al (R =0.96) and Na (R = 0.92). The principle limitation is not the accuracy of the LIBS method but rather the inherent errors in sampling heterogeneous materials such as lignite. Since the LIBS analysis takes less than 30 seconds it has clear advantages over traditional methods used in elemental analysis for these materials. 41-5

Development of an Automatic Ash Fusion Temperature Measurement

Glen Huber, CSIRO Energy Technology, Lindsay Juniper, Ultra-Systems

Technology Pty Ltd, AUSTRALIA

The current Ash Fusion Test (AFT) suffers from variations in results due to operator interpretation of when ash fusion event temperatures (initial deformation, sphere, hemisphere and flow) have occurred. This is particularly true with the initial deformation temperature. The standard AFT often has variations in results as high as 30-50°C for an operator on the same equipment, and 50°-150°C for a different operator in another laboratory. Another problem with the current AFT is that measurements are taken at 20°C intervals. This large interval often leads to operator interpolation when event temperatures occur between measurements or when events occur close together. This is another source of operator interpretation. It is recognised that the ash fusion test needs to be improved in the interpretation of the event temperatures. New methods have been developed to address this problem, including an improved AFT (iAFT), and thermal-mechanical analysis (TMA). The iAFT is based on measuring the height change verse temperature between two tiles separated by pillars of ash. TMA is based on plunger displacement into a crucible of ash that is heated. To date, these techniques have not been widely accepted by industry. This is probably attributable to coal contracts still requiring ash fusion temperatures as specified by the current Australian Standard, and these test are a major deviation from the standard AFT. A recent project funded by the Australian Coal Association Research Program (ACARP) has developed an automatic system, based on digital imaging, that provide a system of ash fusion temperature measurement that will overcome the problems of the current measurement and, as it will be essentially the same test, be fully acceptable to the coal industry and its customers. A normal ash fusion pyramid(s) are placed in a standard AFT furnace and a video image signal is fed to a digitising capture card on a PC at 1°C temperature intervals. Each image that is captured is processed to determine if the current image shows one of the four event temperatures. The steps involve background removal and testing for the shape of the pyramid to determine if a temperature event is evident. If it does, then the temperature is recorded and the test continues until all events have been determined. A commercial prototype has been developed and is now awaiting full commercial development of the system.

SESSION 42 BIOMASS CO-FIRING-I

42-1

Co-Firing of Biomass with Coal: Combustion Issues

Chatphol Meesri, Behdad Moghtaderi, Raj Gupta, Hamid Rezaei, Terry F. Wall,

CRC for Coal in Sustainable Development, AUSTRALIA

The threat of global warming caused by greenhouse gases, such as CO2 has prompted the use of biomass, especially wood and woody materials, as a substitute fuel for electricity production in coal-fired boilers mainly due to its carbon dioxide neutral properties. As a result, the co-firing technology has been used in a number of utility installations across the world including Australia where the Federal Government’s 2% mandated renewable measure for power generation also recognises co-firing as a form of renewable energy. Due to the scarceness of information on the fundamental issues regarding combustion behaviour (pyrolysis and char combustion characteristics) of the blends of coal and woody biomass, this paper is an attempt to address this

47

shortcoming to qualitatively and quantitatively indicates its effects on issues relevant to practical co-firing process. In this paper, studies of pyrolytic behaviours (productions and distributions of pyrolysis products) under both low and high heating rate conditions and burn out characteristics of coal, sawdust and the blends of coal and sawdust and their correlation have been presented. Investigation of char morphology of the coal, sawdust, and the blends of coal and sawdust during devolatilisation has also been included. The impact of pyrolysis and burnout and their implications on issues such as safety in the grinding system, stability of the burner flame and ignition of the pulverised coal particles including the burn out reactivity of the parent fuels and the blended fuels are addressed to provide proper understanding for the co-firing process. 42-2

Co-Firing of Biomass and Coal: A Means to Reducing Greenhouse Gas

Emissions

Kati Savolainen, Risto Sormunen, Fortum Engineering, FINLAND Co-firing tests with sawdust and coal have been carried out at FORTUM's Naantali-3 CHP power plant (315 MWfuel). Naantali-3 plant is a tangentially fired pulverised coal unit with Sulzer once-through boiler that produces 79 MW electricity 124 MW district heat and 70 MW steam. Naantali-3 is equipped with roller coal mills (Loesche), modern low-NOx-burners (IVO RI-JET), over fire air (OFA), electrostatic precipitator (ESP) and flue gas desulphurization plant (FGD). Coal and sawdust were blended in the coal yard, and the mixture was fed into the boiler through coal mills. Tests were carried out totally three months during the April 1999 and March-April 2000 with pine sawdust (50-65 % moisture as received). During the tests sawdust proportions 2.5-8 % (from the fuel input) were examined. The co-firing tests were successful in many ways, but the behavior of the coal mills caused some problems, and therefore the simultaneous feed will not be the solution in a long-term use. Fortum has developed a new concept for co-firing coal and biofuels in large Pulverised Coal fired boilers. The experiences gained from Naantali co-firing tests and good knowledge of low-NOx burning and combustion behavior of different fuels at Fortum, was used when the new co-firing concept was developed. This new concept consists of separate biofuel grinding system and bio- or bio-coal-burners. By using this system, it is possible to utilize many kinds of biofuels in PC-boilers as well as increase the share of biofuels, compared to the simultaneous feed of biofuel and coal. 42-3

Switchgrass Co-Firing with Coal for Power Generation

Doug Boylan, Steve Wilson, Southern Company, Vann Bush, Southern

Research Institute, Bill Zemo, Alabama Power Company, USA

Switchgrass is a hardy, highly productive native American prairie grass which can be grown on marginal cropland. Southern Company, Southern Research Institute, Agtec Development, EPRI, and the U.S. Department of Energy are engaged in a program to evaluate the economics and the environmental benefits of co-firing switchgrass with coal in existing coal fired boilers. As part of this program, a full-scale demonstration was conducted in a tangentially-fired power boiler in which switchgrass supplied up to 10% of the fuel energy input. The objective of the testing was to determine handling, operating, combustion, and emissions characteristics of the co-firing process. A system was designed to accept large round bales and shred the material to less than one-inch pieces. The chopped grass was then conveyed pneumatically into the furnace through dedicated burners located between the coal burner elevations. A series of 40 tests was conducted over a six-week period at Alabama Power Company’s 70 MW Gadsden Unit 2. Tests were performed at various operating conditions including injection of grass at two different levels. Data were taken to evaluate the effect of the switchgrass on boiler efficiency and on emissions such as sulfur and nitrogen oxides. This paper describes these tests and the results obtained, with some discussion of the costs and benefits of switchgrass co-firing.

SESSION 43 TRACE ELEMENTS IN COAL

43-1

The World Coal Quality Inventory (WoCQI): A Tool for Addressing

Global Energy, Technology, Economic, Environmental, and Human Health Issues

Robert B. Finkelman, USGS, USA

Policy makers around the world require accurate information on coal, including coal quality data, to make informed decisions regarding international import needs and export opportunities, foreign policy objectives, technology transfer policies, foreign investment prospects, environmental and health assessments, and byproduct use and disposal issues. Unfortunately, he comprehensive, accurate, current coal quality information needed is generally not available. The U.S. Geological Survey (USGS), in conjunction with partners from about 50 countries, is developing an integrated electronic database (World Coal Quality Inventory: WoCQI). WoCQI will contain coal quality information, including data on about 50 elements, for samples representing prominent coal beds in all of the major coal-producing countries, as well as coals from many of the smaller producers, and will emphasize information from coals currently being burned. The information that will be incorporated into the database includes, but is not limited to, proximate and ultimate analyses, sulfur-form data, major, minor, and trace elements, semi-quantitative analyses of minerals, modes of occurrence, washability, petrography, and other factors that affect technological behavior, economic byproduct recovery, and environmental impact. This information will be linked to Geographic Information Systems databases showing coal basins and sample locations along with geologic, industrial, and cultural information. WoCQI will be accessible on the USGS web page that will be updated on a regular basis. This multi-national cooperative effort in developing a reliable, comprehensive, global coal quality database that contains a broad array of technologic, economic, and environmental parameters should help to ensure the efficient and environmentally compatible use of our global coal resources in the 21st Century. 43-2

Partitioning of Potentially Hazardous Trace Elements in Coal Combustion

Lesley L. Sloss, Robert M Davidson, IEA Coal Research, UK

An international collaborative programme involving eight laboratories in five countries was coordinated by the IEA Clean Coal Science programme in order to evaluate the modes of occurrence of trace elements in coal. Four power plant bituminous coals were studied, one each from Australia, Canada, the UK and the USA. Trace element concentrations were determined for the whole coals but the coals were also fractionated using physical separations and sequential solvent extraction. The collaboration concentrated on 13 elements: Be, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Hg and Pb. The programme produced consistent agreement concerning the modes of occurrence of arsenic, selenium, and lead; reasonable agreement on chromium, manganese, copper, zinc, cadmium, and mercury; but little agreement on beryllium, cobalt, nickel, and antimony. Most trace elements, mercury and selenium excepted, are emitted on the particulate matter. Their properties and that of the coal mineral hosts can affect how they are partitioned among the various size fractions of the ash. The important factors which affect trace element partitioning in combustion products include concentration as a function of particle size, vaporization, speciation and affinities in fly ash, and chemical properties. Various correlations and prediction equations have been published to help understand this partitioning. Computer models can be used to predict emissions from coal properties. However, even when emissions can be accurately predicted, default values should only be used with extreme caution. Legislation on trace element emissions from coal combustion, especially mercury, may be imminent in countries such as the USA. As a result there is now a move towards establishing the best means of reducing trace element emissions. Existing pollution control equipment for emissions such as particulates, SO2 and, NOx is also effective in reducing emissions of most trace elements. However, the more volatile trace elements, such as mercury, are captured to a much lower extent in coal-fired power stations. The current confusion over the best approach to control the more volatile trace element emissions is a reflection of the lack of reliable data. 43-3

Strategies for the Removal of Selenium from Ash Dam Waters

K.W. Riley, O. P. Farrell, S. Wheeler, CSIRO Energy Technology,

AUSTRALIA Selenium is often found at high levels in the fly ash ponds of coal-fired power stations. The discharge of this water into the surrounding environment can have a detrimental effect on aquatic biota including fish. Hazardous levels can also be reached in water birds. Although selenium is an essential trace element, there is only a small margin between beneficial and potentially harmful levels. Coal-fired power plants are a major anthropogenic source of selenium to soil and water environments. Selenium is enriched in the fly ash and if this ash is stored in dams, then there is the possibility of contamination of natural water systems. Unfortunately “dry” repositories and reclaimed ash dams are also possible sources of contamination. There is a need for a cost effective and efficient

48

means of removing selenium from the dam water prior to discharge or alternatively to bind selenium to the fly ash to prevent its subsequent release. In this paper, processes to treat ash dam waters are compared. There is a number of alternative approaches that may provide a solution to a problem that occurs worldwide: a) use of anaerobic bacteria in large scale bioreactors b) coprecipitation with ferric oxyhydroxide c) direction addition of ferric compounds to fly ash d) addition of ferric or ferrous salts to the anoxic and sulfidic water column of ash dams e) formation of “green rusts” f) reduction with elemental iron Results of laboratory experiments are used together with results published by other researchers to recommend possible strategies to minimise the release of selenium from power station ash impoundments. 43-4

Trace Elements in Coal and Flyash by rf-Source Glow Discharge Mass

Spectrometry

LeRoy Jacobs, Charles Wilson, Stephen Ellis, Jane Thomas, Wyoming Analytical Laboratories, Inc., USA

The installation of an rf-source glow discharge mass spectrometer (rf-GDMS) was recently completed in our laboratory. Initial application of the instrument to trace and ultra trace elemental analysis in insulating samples, such as coal and flyash, has been accomplished without the usual solubility problems. A brief explanation of the high resolution, double focusing, magnetic, inorganic, solids mass spectrometer (VG 9000) will be given. Application of the GDMS to trace element analysis of conducting and semi-conducting materials has long been known and presented, but combining the multi-element determining characteristics of the GDMS with rf-source to nonconductors (insulating samples) can now be achieved using relatively simple non-contaminating solid sample preparation techniques. Several applications of the rf-source GDMS to insulating or non-conducting "analytically nasty" samples and several different coals and flyashes will be presented. 43-5

The Determination of Halogens in Coal

Les Dale, K.W. Riley, R.C.Rowland, R. Wood, B.P.Warden, CSIRO Energy

Technology, AUSTRALIA

The significance of chlorine, fluorine, iodine and bromine in coal relates to their role and fate in combustion processes. Chlorine is corrosive and its presence in coal is considered detrimental in coke-making and coal-fired boilers for electricity generation. Atmospheric emissions of chlorine are also of concern in coal combustion technologies. Fluorine is considered toxic and air emissions are of particular concern in horticultural regions. Iodine and bromine have low abundances in coal are of little concern. The specification of chlorine and fluorine in saleable coals has been the subject of much dispute and uncertainty. Standard methods for chlorine are based on bomb combustion (ASTM D2361 and D4208), tube furnace combustion (DS 1038.8.2) or combustion in the presence of Eschka Mixture (AS 1038.8.1). All procedures require a titration or ion selective electrode (ISE) to measure chloride in solution. These methods are insensitive with a lower limit of detection of approximately 0.01% with a repeatability also of 0.01%. There are a number of standard methods for the determination of fluorine. In Australia, AS 1038.10.4 is used. This method is a pyrohydrolyis/ISE or pyrohydrolyis/IC method, ASTM D5987 in the US. Three are difficulties in the application of pyrohydrolyis-based procedures as these require skilled operators. The alternative bomb combustion/ISE procedure ASTM D3761, according to reports in the literature, gives low recoveries for some coals. At CSIRO new analytical methods for halides in coal have been developed which substantially improve the accuracy and reliability of the determination. The methods are based on X-ray fluorescence spectrometry, inductively coupled plasma atomic emission spectrometry and proton accelerator irradiation. The new method for fluorine, based on a sinter and fusion, followed by ISE shows promise of providing good accuracy. These new methods will be described and their suitability for general laboratory use discussed.

SESSION 44 SYNTHESIS GAS UTILIZATION-I

44-1

The Application of Fischer-TROPSCH and SASOL: Current and Future

Christiaan Reinecke, B Jager, Sasol Technology (Pty) Ltd, SOUTH AFRICA

Sasol has over many years applied Fischer-Tropsch technology to convert coal derived syngas to fuels and chemicals. The more recent exploitation of natural gas as feedstock for syngas has given to a spur to the in development of Fischer-Tropsch related applications. This has lead to several exciting catalyst and process developments which can be applied to coal to liquids as well. In this paper an overview of the current status of Fischer-Tropsch technology within Sasol is given. An update on the latest developments in terms of Sasol’s involvement in gas-to-liquids projects will also be given. An overview will be given on the challenges that Fischer-Tropsch technologies are faced with and the research and development efforts that are currently being made at Sasol to address these. Some attention will be paid to the latest research focus on both iron and cobalt catalysis. Fischer-Tropsch was traditionally employed to produce fuel. The change in business focus of Sasol is moving its application more towards chemicals. An overview will be given on these developments and it will be linked to Sasol’s research activities. 44-2

Polygeneration in a Competitive Electricity Market

J. Sligar, Sligar and Associates, USA

Competitive electricity markets are designed to drive down the price of electricity towards the short run marginal cost so that the incentive for investment in new facilities becomes a matter of concern. Signals and drivers are built into the market structure to try and ensure new plant is installed to maintain an adequate reserve margin on the respective power system. With the move to make electricity a commodity other ways must be found to induce investment in new facilities. An elegant solution is to produce higher value products together with commodity electricity. In this way adequate profit can be assured while at the same time providing competitive power into the system or network. Coal is ideally suited as a resource for this role, especially where there is no gas pipeline nearby or gas is too expensive. Coal can be gasified and converted into many high value chemicals while using some output from the plant to generate electricity. This is termed Polygeneration, the production of electricity together with a number of valuable products. Typical products include ammonia, fertilizers, sulphuric acid and hydrogen depending on the properties of the coal used and local markets for these products. By using gasification techniques on coal rather than conventional ultra super critical generation, products such as carbon dioxide are in relatively high concentrations, facilitating sequestration at an economic cost. There are numerous examples of this combination of technologies that have developed because of local conditions. Eastman Chemicals has been operating a coal gasification plant for many years, using the product gas to manufacture chemicals and also generating power. Ube Ammonia has been converting Australian coal into ammonia and fertilizers using gasification technology for many years. It also provides power for the Japanese power grid. A further example lies in the possibility of producing hydrogen from coal for transport fuel. 44-3

Synthesis Gas from Gasification of Waste and Coal

Thomas Obermeier, Sekundärrohstoff-Verwertungszentrum Schwarze Pumpe

GmbH, GERMANY

From 1992 on the former lignite fired gasification plant in Schwarze Pumpe, Germany, was converted into a modern recycling centre for solid an fluid waste and residues. The heart of the recyling plant are three different types of gasifiers: 7 Fixed bed gasifiers, 2 Multi purpose gasifiers (MPG) and a new BGL-gasifier (British-Gas-Lurgi). In all cases oxygen is used as gasification agent. Over 200 Mio € were invested in the last years to modernize the gasification complex and the peripherie. In 2000 were over 250.000 tons solid and fluid waste gasified. Solid waste is gasified together with only 15-25% coal or lignite briquettes. It is possible to use

49

a wide range of waste, such as plastics, MSW, sewage sludge, car shredder residue, contaminated wood etc. Inputmaterial for the MPG are different oils, slurry products, tar oil etc. Syngas is converted in an methanol plant to 120.000 ton per year methanol grade AA and electrical energy in a 45 MW gas turbine. Three quarters of the methanol production are used for chemical products, in the future the using for fuel cell will increase. The attraction of the concept realized at SVZ is, that it allows the material recycling of a wide range of waste and residues into a „raw“-material for the chemical industry in an efficient and environmentally friendly way. In 2005 the gasification capacity of SVZ will increase to 1 Mio ton per year.

SESSION 45

ADVANCED GAS SEPARATIONS

45-1

Separation of Hydrogen and Carbon Dioxide in Advanced Fossil Energy Conversion Processes using a Membrane Reactor

Ashok S. Damle, Research Triangle Institute, USA

Advanced gasification-based energy conversion systems offer opportunities for high energy conversion efficiency, superior environmental performance, and flexibility in product portfolio. Hydrogen separation plays a vital part in the advanced energy conversion systems not only to convert fuel values to hydrogen for efficient power generation by fuel cells but also to adjust the CO:H2 ratio for liquid fuels production. Converting the synthesis gas to hydrogen by reforming reactions also allows CO2 capture prior to combustion increasing overall power generation efficiency and reducing the cost of CO2 capture and hydrogen generation. By conducting fuel reforming with simultaneous hydrogen separation in a catalytic membrane reactor unit, equilibrium-limited reforming reaction is driven to completion maximizing hydrogen generation. The fuel carbon content is recovered in a compressed, sequestration-ready CO2 form. A key enabling technology for this advanced energy systems concept is separation of hydrogen and carbon dioxide. Palladium is known to be completely selective for hydrogen, however, palladium metal alloy tubes are expensive for commercial applications and also exhibit very low hydrogen flux rates due to the thickness necessary for structural stability. This paper describes development of a membrane reactor process based on thin palladium-silver alloy films deposited on a porous substrate such as alumina or sintered metal. By utilizing a thin yet structurally stable composite membrane, hydrogen flux is increased while reducing costs. Electroless plating technique is used to prepare thin (2 to 3 micron) palladium-silver alloy films on commercially available tubular substrates. The observed hydrogen flux rates are of the order of 1 gmole/m2-sec at 500-600 oC temperature and 40 psi hydrogen partial pressure differential. Simultaneous separation of hydrogen during reforming reaction leads to substantially increased CO conversion limited only by the residual hydrogen in the feed gas exit. Potential target applications identified in the preliminary techno-economic analysis include: 1) reforming of fuel gas to produce hydrogen for stationary power generation using proton exchange membrane (PEM) fuel cells, 2) On-board fuel reforming for power generation in transportation application, and 3) hydrogen separation and adjustment of H2:CO ratio involved in production of liquid fuels/chemicals from synthesis gas. Several other applications are also possible for the palladium-based membranes both as a membrane reactor e.g. in dehydrogenation reactions and simply as a hydrogen separation and recovery process. This paper will present the results of experimental evaluation of the composite membrane performance both as a hydrogen separation unit and as a membrane reactor for fuel reforming. 45-2

Development of Dense Ceramic Membranes for Hydrogen Separation

U (Balu) Balachandran, T. H. Lee, S. Wang, S. E. Dorris, Argonne National

Laboratory, K. S. Rothenberger, U.S. DOE/NETL, USA

The Office of Fossil Energy in the U.S. Department of Energy is formulating a program called "Vision 21," which aims to develop highly efficient power and coproduction technologies that close the carbon cycle and discharge almost no pollutants. As part of this program, Argonne National Laboratory (ANL) and the National Energy Technology Laboratory (NETL) are developing dense ceramic membranes for separating hydrogen from coal gasification and other partial-oxidation-product streams. Hydrogen separation with these membranes is nongalvanic, i.e., does not use electrodes or external power supply to drive the separation, and the selectivity for hydrogen is nearly 100%, because the membranes contain no interconnected porosity.

Our efforts to develop hydrogen-separation membranes initially focused on BaCe0.8Y0.2O3-δ (BCY), a proton/electron conductor whose high total electrical conductivity suggested that it could support a substantial hydrogen flux. Early measurements showed, however, that the electronic conductivity of BCY was insufficient to provide a significant hydrogen flux, therefore we developed novel cermet (i.e., ceramic-metal composite) membranes by adding various metals to BCY. A nongalvanic hydrogen flux was measured with two such membranes (ANL-1 and -2), but ANL-2 gave a much higher flux because its metal has a larger hydrogen permeability. Based on these results, ANL-3 cermet membranes were developed in which the metal phase provides a path for hydrogen diffusion while the ceramic phase supplies mechanical support. Among the various cermet membranes, ANL-3 gave the highest hydrogen flux: 5.9 cm3(STP)/min-cm2 for a 0.1-mm-thick membrane at 900ºC using a feed gas of 100% hydrogen at ambient pressure. The effects of membrane thickness and hydrogen partial pressure on flux indicate that bulk diffusion of hydrogen is rate-limiting for ANL-2 and -3 membranes, which suggests that the flux can be increased by further reducing the membrane thickness. During ≈190 h of operation at several temperatures in simulated syngas, ANL-3 membranes showed no decrease in hydrogen flux, suggesting that the membranes are chemically stable and may be suitable for long-term operation. The present status of membrane development at ANL/NETL will be presented in this talk. 45-3

Catalytic Membrane Reactors for Environmentally Benign Coal Processing

Anthony F. Sammels, Eltron Research Inc., USA

Under support from the U.S. Department of Energy and the Federal Energy Technology Center Vision 21 initiative, Eltron Research Inc. is developing catalytic membrane reactors (CMRs) which address several key technical issues relating to coal utilization. In particular, a new generation of mixed oxygen anion and electron conducting membranes are under development derived from oxygen-deficient metal oxides possessing the general stoichiometry A2-xA´xB2-yB´yO5+z. CMRs based upon these materials have resulted in spontaneous coal gasification using oxygen separated, via the membrane, from the atmosphere and operate below the coal slagging temperature. CMRs with a demonstrated ability for rapid proton and electron conduction are also being developed as an efficient method for separating hydrogen from gas mixtures produced during industrial processes, such as coal gasification. This strategy seeks to economically eliminate environmental concerns associated with the use of fossil fuels. Once fully developed, this approach is expected to reduce hydrogen cost, a clean burning fuel under increasing demand, as supporting technologies are developed for hydrogen utilization and storage. The current status of these CMR technologies under development at Eltron Research Inc. for both coal utilization and related environmental control issues will be discussed.

SESSION 46

COAL COMBUSTION BYPRODUCTS UTILIZATION-III

46-1

Utilization of PCC Fly Ash and Dry Bottom Ash Portland Cement Composites in Deep Foundation

Nader Ghafoori, Tennessee Technological University, S. Kumar, V. Puri, S.C.

Ng, Southern Illinois University, USA

The research presented herein is intended to examine the extent to which Illinois Pulverized Coal Combustion (PCC) fly ash and dry bottom ash can be used, as a secondary cementitious material and a fine aggregate, respectively, in construction of drilled shafts. Four different Portland cement composites and a reference concrete were investigated. A constant water-to-cementitious materials ratio of 0.47 and a cement factor of 564 pcf were used throughout the investigation. The PCC fly ash was used to replace 10, 20, and 30% by mass of Portland cement. Laboratory studies included short-term (slump, bleeding, and setting times), intermediate-term (compressive, splitting-tensile, and flexural strengths; and elastic modulus and poission’s ratio) and long-term (resistance to external sulfate attack, sealed shrinkage, swelling, and resistance to freezing and thawing) characteristics. Test results reveal that Illinois PCC dry bottom ash and fly ash Portland cement concretes displayed excellent mixability, consolidability, and finishability similar to that of the reference mixture. Under the adopted uniform water-to-cementitious materials ratio, the trial materials produced higher slump, bleeding, and setting times when compared to those of the reference concrete. However, they all remained within the acceptable limits seen for conventional concrete.

50

Late-age strength and stiffness properties of the PCC Portland cement matrices were similar to those of the equivalent control concrete. Inclusion of the PCC dry bottom ash and fly ash had more influence on tensile resistance than on compressive strength. The sealed shrinkage and swelling of the trial PCC dry bottom ash and fly ash concretes were higher than those of the equivalent control mixture. The PCC dry bottom ash and fly ash concretes also produced higher mass losses due to freezing and thawing actions and slightly less resistance to external sulfate attack when compared to those of the reference mixture. On the whole, the trial PCC Portland cement matrices displayed short-, intermediate-, and long-term characteristics which were comparable to those of the equivalent control concrete. 46-2

Treatments for Lowering Foam Index in High-Carbon Fly Ashes for

Concrete Applications

Robert B. LaCount, Tiffany A. Leyda, Keith A. Giles, Patrice J. Pique, Waynesburg College, John P. Baltrus, J. Rodney Diehl, U.S. DOE/NETL,

Timothy L. Banfield, Allegheny Energy Supply, Douglas G. Kern, ViRoLac Industries, USA

Commercially, fly ash is often used as a replacement for some of the Portland cement in concrete products. Surfactants, used to entrain air in the concrete mixtures, improve the workability of the mixtures and the durability of the concrete products to freeze-thaw cycles. The use of low-NOx burners in coal-fired boilers has resulted in variable increases in the unburned carbon content of fly ash. When high-carbon fly ashes are used in concrete, often an increase in the amount of surfactant is required. The foam index (FI) test, which involves titration of a portion of the concrete mixture with an aqueous solution of surfactant until a stable foam results, is used to determine the amount of air entraining agent required in the concrete. This paper describes the results of various research efforts directed towards developing a practical and economical thermal treatment for high-carbon fly ash that would reduce its FI without having to remove the carbon. For the purposes of this study, thermal treatments were carried out using a controlled-atmosphere programmed-temperature oxidation (CAPTO) partial oxidation or pyrolysis treatment. Temperature ramp, gas flow, and pressure were all under software control. Analytical CAPTO profiles were completed on fly ash obtained from pulverized coal-fired utility boilers burning Pittsburgh seam bituminous coals under low-NOx conditions. The gases (CO2, H2O, and SO2) evolved during CAPTO analysis were monitored as a function of temperature. Progressive partial oxidation and pyrolysis of the fly ash samples were accomplished by a linear increase in temperature accompanied by plug flow under both an oxidative and inert gas atmosphere. The effects of variation in ramp rate and total thermal treatment time were explored. The FI values of the treated samples were significantly lower compared to those for the untreated fly ashes, and were found to vary depending on the treatment parameters. Selected untreated and treated samples were characterized using X-ray photoelectron spectroscopy, leachable-ion conductivity measurements and other methods in an attempt to correlate any changes in physical and chemical properties of the fly ashes with changes in FI brought about by the thermal treatments. Based on thermal treatment results, sufficient quantities of several fly ashes are being treated to lower their FI values and then evaluated for use in preparing concrete test samples. These results and the CAPTO profiles will be discussed. 46-3

Laboratory and Field Performance of Fly Ash Concrete in Marine

Environments

Radhe Khatri, Vute Sirivivatnanon, CSIRO, AUSTRALIA

The longevity of concrete in a marine environment is strongly related to its long-term performance. Due to time constraints, the long-term performance is impractical to measure in a laboratory. Thus a field study was carried out to supplement the findings of laboratory studies to evaluate the durability of fly ash concrete in a marine environment. In a laboratory study, the performance of fly ash (FA) concrete of three grades were compared to concrete prepared from a general purpose portland cement (GP). The performance of both types of concrete in a coastal and marine environment was evaluated. Since the range of curing on site is fairly large, concrete was subjected to four types of curing to evaluate the effect of curing. In field study, FA concrete exposed to aggressive marine environment for over thirty years was studied. The performance of FA concrete was compared to GP concrete exposed to similar environment. Both concrete were part of an Outfall Canal of a Power Station and this canal carried warm (40ºC) sea water.

In laboratory study, FA concrete were found to have significantly superior resistance to marine environment than similar 28-day strength GP concrete. The better performance of FA concrete was observed even for concrete subjected to limited curing. In the field study, both FA and GP concrete were found to have similar resistance to marine environment, in spite of, FA concrete having much lower strength. Thus similar strength FA concrete is expected to have significant superior resistance in a marine environment. 46-4

Potential Non-Fuel Uses of Unburned Carbon From Fly Ash for Value Added Carbon Products

M. Mercedes Maroto-Valer, Yinzhi Zhang, Zhe Lu, John M. Andrésen, Harold

H. Schobert, The Pennsylvania State University, USA

The implementation of increasingly stringent US Clean Air Act Regulations by the coal utility industry has resulted in an increase in the concentration of unburned carbon in coal combustion fly ash. In 1998, around 5-8 million tons of unburned carbon were disposed in US, due to the present lack of efficient routes for its utilization. However, the increasingly severe regulations on landfill and the limited access to new disposal sites with the subsequent rise in the cost of disposal, may demand the utility industry to begin offsetting coal combustion with natural gas, or require additional coal cleaning to remove the ash prior to combustion, or simply start utilizing the unburned carbon. The authors have previously conducted extensive studies on the characterization of unburned carbon and showed that its properties are similar to those of conventional precursors for the production of premium carbon materials. Accordingly, this study focuses on the potential for the generation of premium carbon products from unburned carbon present in fly ash. Fly ashes were collected from two coal-fired power plants that have units retrofitted with low-NOx burners. The samples from hoppers on the first row (hot-side) of the electrostatic precipitators present the lowest LOI values (~10%), while bins in the last row (cool-side) present the highest LOI values (40-50%). Therefore, these cool-side bins were suitable hoppers for the collection of high carbon content ashes as feedstocks for carbon materials precursors. Firstly, the ability of unburned carbon to generate activated carbons by steam activation was assessed. After 120 minutes activation time, the unburned carbon samples generated activated carbons with microporous structure and surface areas up to 1200 m2/g. Despite the low particle size of the unburned carbon samples, the solid yields are relatively high, since the unburned carbon has already gone through a devolatilization process in the combustor. For the second route regarding the use of unburned carbon as a precursor for carbon bodies, the unburned carbon samples were mixed and pelletized with calcined petroleum coke and coal tar binder pitch. The unburned carbon presents similar heat treatment (temperatures 1200-1400°C) and slightly higher H/C ratios than conventional petroleum coke, but it exhibits lower density than petroleum coke, probably due to its larger surface area. However, the density of the carbon pellets prepared with unburned carbon is comparable to that using only petroleum coke, due to a strong interaction between the unburned carbon and the coal tar binder pitch 5. Therefore, the unburned carbon acts as a good filler for the carbon pellets produced and further tests will be performed to assess whether unburned carbon can be used as a replacement for the fine fraction of petroleum coke in the manufacture of carbon artifacts. 46-5

Trace Element Partitioning in Fly Ash at a Kentucky Power Plant

Tanaporn Sakulpitakphon, James C. Hower, Alan S. Trimble, William H.

Schram, Gerald A. Thomas, University of Kentucky, CAER, USA

Coal and fly ash were collected from a 500 MW Kentucky power plant with the objective of studying the distribution of As, Hg, and other trace elements in fly ash. The coal feed at both collection times was high volatile A bituminous Central West Virginia coal. The plant produced a relatively low-carbon fly ash. In contrast to power plants with high-Hg feed coal, the fly ashes from the lower-Hg feed coal had low Hg values, generally not exceeding 0.01 ppm Hg. Hg-capture by fly ash is a function of both the amount, and type, of carbon and the collection temperature, Hg capture being more efficient at lower temperatures. Arsenic in the feed coal and in the flue gas is of concern to the utility due to the potential for catalyst poisoning in the SCR system (currently under construction). Arsenic is captured in the fly ash, increasing in concentration in the more distant (from the boiler) reaches of the ESP system. The unit does not currently operate a flue-gas desulfurization system, therefore trace elements not captured by the fly ash would pass through the SCR unit.

51

SESSION 47 MODELING ON COAL COMBUSTION UTILIZATION

47-1

A Predictive Model for Viscosity of Molten Coal Ash Slags

L. Zhang, S. Jahanshahi, S. Sun, G K Williams CRC for Extractive Metallurgy,

H. J. Hurst, J. H. Patterson, CSIRO-Division of Energy Technology, AUSTRALIA

Prediction of thermodynamic behaviour and viscosity of coal ash slags is important to the development of coal based integrated gasification combined cycle (IGCC) power generation technology. A thermodynamic model (MPE) that calculates multiphase equilibrium and viscosity of the slag phase has been developed at the G. K. Williams Cooperative Research Centre for Extractive Metallurgy (GKW CRC) in the past decade. The model is capable of predicting the solid, liquid and gaseous phases formed at equilibrium during coal gasification. It also calculates viscosity for both liquid slags and slag containing solid particles. The viscosity model developed at the GKW CRC uses the structural parameters obtained directly from the thermodynamic model of the slag phase. The unique feature of the viscosity model is that only parameters for binary silicate melts are required for prediction of ternary and multi-component systems. A new set of self-consistent viscosity data in the composition range, which covers Australian coal ash and fluxed coal ash slags, has been measured in a systematic manner in recent years. The comparison between the data and the predicted viscosity values using the viscosity model showed that good agreement was obtained. Examples of prediction of phase equilibrium and viscosity will be given to demonstrate the applicability of the MPE model for the coal ash and fluxed coal ash slags in the CaO-FeOx-Al2O3-SiO2 system. 47-2

Microstructure of Carbonaceous Materials: Experimental and Computer

Modelling Investigation

T. Petersen, D. McCulloch, I. Snook, I. Yarovsky, RMIT University, P. Zulli, BHP Steel Research Laboratories, AUSTRALIA

A fundamental understanding of physical and chemical interactions of carbonaceous materials (coal, coke, char) with molten iron is critically important to both the blast furnace (BF) ironmaking operations and the selection of raw materials for the process. For example, accumulation of fine powder (char, coke) in the lower zone of the BF contributes substantially to the deterioration of gas permeability within the BF and hence may represent a major obstacle for sustaining both stable furnace operation and optimal hot metal quality. These problems are of further concern with the current practice of injecting pulverised coal into the BF. The consumption of carbonaceous materials in the BF lower zone takes place via a number of mechanisms including the dissolution of carbon into molten iron. Studies have shown that one of the major factors influencing the dissolution rate of carbonaceous materials is the degree of “graphitisation”. Characterised by the width of the [002] peak observed in X-ray diffraction pattern, the Lc parameter may be used to estimate the average crystallite size of small graphitic regions within disordered carbonaceous materials1. Currently, very few systematic investigations of the carbon microstructure (beyond the Lc parameter) and its possible effects on the dissolution rate have been carried out. Due to the observed correlations between carbonaceous dissolution and Lc parameters, the current study seeks to elucidate the microstructure of various solids using a combination of experimental and theoretical techniques. Structural simulations are being performed using the increasingly popular “Reverse Monte Carlo” method2. Molecular dynamics simulations of various model structures will lso be explored, so as to aid in the structural characterisation process. Using generated statistical atomic models of the experimental samples, key structural features will be correlated with the dissolution performances in the final stages of the project. 47-3

Computer Modelling of Physical-Chemical Properties of Complex Coal Ash

Slag Systems in Multi-Dimensional Compositional Space

Igor Vladimirov, Shannon Christie, Evgueni Jak, CRC for Coal in Sustainable Development, AUSTRALIA

New advanced chemical thermodynamic database for the SiO2 -Al2O3-CaO-FeO-Fe2O3 system has been developed in conjunction with the thermodynamic computer package F*A*C*T. The model has been successfully applied to

characterise high temperature melting behaviour of the coal ash slag systems and assist in investigation of a number of industrial and research coal mineral matter related issues. To make the model prediction available to a wider research and engineering community, this model is now used as a basis for further development of the custom computer representation modules. These independent modules will enable to transfer important physical-chemical information on the complex multi-component coal ash slag systems in a simple-to-use way to a wider coal utilisation research and industrial community for a wide range of technological, research, education and training industrial applications. The paper will present development of a non-traditional mathematical scheme for spline-approximation of a specific piece-wise smooth function in several variables given on a grid with complex geometry which provides a F*A*C*T-independent representation of the phase equilibria, in particular, liquidus temperatures, in a multi-component composition space. The liquidus – temperatures at which first solid starts to precipitate on cooling of a chemical system - have special complicated geometry determined by thermodynamics. The liquidus is smooth within any constant phase assemblage zone. Over the whole composition space, the function is only piece-wise smooth, with the non-differentiable points at the boundaries where the phase fields meet each other. The mathematical scheme has substantially taken into account these features of the approximated functions. To achieve that, a non-traditional spline approximation scheme has been developed, based on multiple cubic spline interpolation combined with least squares method extrapolation of smooth components of the function beyond the phase fields. This was necessary to ensure its high-precision approximation not only inside the phase fields but also in the neighbourhood of the phase field boundaries. This multiple cubic spline approximation scheme has then been used for post-

calculation of applied properties, in particular, for prediction of the Ash Fusion Temperatures. The mathematical description of the coal ash slag liquidus and Ash Fusion Temperatures have been incorporated into a dedicated computer package – Coal Ash Fusion Temperature and Liquidus Calculator - which is easy-to-use, and at the same time is a powerful scientific, research and technological tool (see Figure). The Ash Calculator has already been successfully applied to assist in coal blending and mine planning. The work outlined in the paper has already been used by coal utilisation researchers and engineers, and received numerous positive comments. This new mathematical algorithm can now be applied to other practical issues. In particular, at present the new mathematical scheme is used as a basis for development of computer modules for 2D and 3D visualisation of phase equilibria (liquidus and other characteristics) and of other physical-chemical properties of the coal ash slag systems in the n-component composition space. The emphasis in the paper will be given to the current and future applications of the new mathematical algorithm to the coal utilisation technologies and research. The work outlined in the paper has been undertaken as part of the Collaborative Research Centre for Black Coal Utilisation with assistance from the BHP Coal Ltd. 47-4

Numerical Model of Ash Deposition Behavior in the Pilot Scale Entrained-

bed Gasifier

Byung-Pyo Lim, Byung-Chul Choi, Hyung-Taek Kim, Ajou University, Young-Don Yoo, Institute of Advanced Engineering KOREA

Mineral deposit in the heat exchanger surface of typical entrained-bed coal gasifier represents adverse effect on the operation and efficiency of gasifier. Based on the more than 5 years of operation experience for 10 different coals, deposition behavior should be related the composition of coal ash rather than operating conditions of gasifier. In this paper, ash deposition behavior of gasifier is compared with the findings in lab-scale DTF experiments and a numerical model will be developed to predict the high-temperature ash behavior in the surface of heat exchanger. To simulate ash deposition environment inside gasifier, cylinder-type DTF will be utilized in the experiment. Several samples of pulverized coal are introduced

52

at the top of DTF with the feed rate of 0.3g/min and the reacted ash samples are collected on the specially designed deposition probe. After the weight analysis, the samples are analyzed with SEM for the composition of ash of every layer of deposition. Ash deposit samples of pilot-scale gasifier are also investigated by the thin section method of SEM. Within various physical and chemical properties of coal, mineral component is generally considered as dominant parameter to determine ash deposition. In the development of numerical model, deposition rates of deposit-initiating mineral, such as Na or K compounds are calculated with various conditions. Also, the effect of major component of coal ash on the deposition is coupled with the deposition-initiating rate. Finally, developed numerical model of ash deposition will be refined with the ash deposition behavior of DTF experiment as well as actual pilot-scale experiment. . 47-5

Computational Modelling of NOx Emissions from A 350 MW P.C. Fired

Boiler

S. P. Visona, Sigma Process Solutions, A. Williams, University of Queensland, AUSTRALIA

Combustion modelling has been carried out on the furnace of a 350 MWe utility boiler fired on pulverised coal. Furnace exit NOx predictions are made using two approaches for the gas phase kinetics. The first approach uses De-Soete gas phase reaction kinetics as the basis for the simulation and the second approach uses simplified NOx gas phase equations obtained by reducing a full set of gas phase NOx equations. The reduced equations were constructed using simulations performed with Chemkin and the Grimech3 reaction mechanism. The simulations used mixtures of CH4/O2/N2 at various equivalence ratios, temperatures and with the fuel N species NH3, HCN and NO. Simplified equations were developed that fit the gas species profiles and a series of parameters calculated for the conditions studied. The mechanism developed predicts profiles at other conditions by interpolating the parameters and calculating a source term from the profile to be used in the 3D furnace model. Field measurements have also been carried out both in-flame and at the exit plane of the furnace. A 9 m long water cooled probe was used for the in-flame measurements and a 6 m water cooled suction pyrometer for the furnace exit measurements. Using FTIR analysis the in-flame measurements confirmed the location and the extent of the NOx precursors HCN and NH3. The furnace exit plane measurements confirmed that the gross flow structure within the furnace was being correctly modelled. Exit plane measurements included flue gas analysis as well as furnace exit gas temperature measurements. Detailed exit NOx measurements showed the presence of steep concentration gradients which are a result of flame to flame interaction within the furnace.

SESSION 48

BIOMASS CO-FIRING-II

48-1

Research and Development for Manufacturing and Combustion Technology of RPF( Refuse Paper and Plastic Fuel)

Masaharu Sasakura, Yasufumi Sakakida, Ken Yamaguchi, Hiroshi Fukuda,

Kawasaki Heavy Industries, LTD, Ryohei Miura, Shinji Ikeda, NEDO, JAPAN

Realization of a society based on recycling is essential to the preservation of the global environment and the earth’s natural resources, and the effective use of energy recovered from waste, a form of unused energy, is important for reducing the emission of carbon dioxide, a greenhouse-effect gas. With the active enforcement of the recycling law for containers and packaging in April 2000 in Japan, there are expected to be increases in the quantities of waste papers and plastics to be collected separately from other wastes. Accordingly, great promise is seen in the manufacture of solidified fuel from these combustible wastes (RPF: Refuse Paper & Plastic Fuel) and the effective use of this fuel as a substitute for coal. However, to make this possible, the chlorine contained in waste papers and plastics has to be reduced to levels low enough to preclude troubles with combustion. As another means to prevent global warming and promote the recycling, Kawasaki Heavy Industries, LTD entrusted from New Energy and Industrial Technology Development Organization(NEDO) has been aiming at the development of RPF manufacturing and combustion technologies. NEDO and Kawasaki presents up-to-date R&D of these technologies from basic studies to demonstrative operations .

48-2

Development of a Cycloid Combustion System for Lignite and Co-Combustion of Sewages Sludge and Biomass with High Efficiency and Low

Emission

Steffen Griebe, Energieressourcen-Institut e. V. Cottbus (ERI), Hans Joachim Krautz, Brandenburgische Technische Universität Cottbus (BTU), GERMANY

At present a research project is being carried out at the Energieressourcen-Institut e. V. / BTU Cottbus in co-operation with the companies Lausitzer Braunkohle AG (LAUBAG) and BBP Environment GmbH (formerly L. & C. Steinmüller GmbH), and is supported by the BMWi (German ministry of research and education). The cycloid combustion system, a furnace developed and introduced to industrial use for the thermal utilization of activated coke and of communal sludge, will be further improved for an efficient and clean lignite conversation. The aim of this project is the development of an efficient and ecologically friendly plant concept for a decentralised provision of heat using local lignite. For the technical realisation of the research and development project for cycloid combustion system, a power plant test facility has been constructed Energieressourcen-Institut e. V. / BTU Cottbus at a location in Jänschwalde. Main components of these test facility are a 0,6 MW smoke tube boiler and a 0,5 MW cycloid combustion chamber. In the first phase of this project the functionality of the cycloid combustion system using local lignite was investigated under permanent operating conditions. Beside the combustion chamber, the other preceding and following components of future plants for the decentralised provision of heat concerning the operating performance were included the investigation as well. The focus of the second phase was the combustion and emission behaviour in relevant operating conditions. The multi level air supply, combustion temperature, excess air, the rate of recirculated flue gas and the adding of desulphurisation additives were important influencing factors. Comprehensive results were ascertained for the flue gas components CO, NOx, N2O and SO2. Because of the combustion of the fuel particles in an upwards directed rotational current in the combustion chamber at temperatures from 800 to 950 °C, the cycloid combustion system is suitable for a wide range of fuels, especially low-quality fuels with low pollutant emission. In the following project phase, the additional combustion of moist sludge and raw material, e.g. woodchip from quick growing trees from recultivated areas of the LAUBAG the local mining company, depending on the calorific value will be investigated. These investigations will be supported by the development of a mathematical process model for the specification of the process technology of the cycloid combustion system. The aim is the theoretical investigation of different operational behaviours of the cycloid combustion chamber. Firstly the flow conditions were investigated at an isothermal model (test facility) of the cycloid combustor on a reduced scale of 1 : 2,4. Based on these results, numeric simulations are now carried out with the commercial CFD program FLUENT. The aim of these first theoretical tasks is the development of a predicted mathematical model for description of the single-phase flow. This should be the basis for statements to the optimisation of the geometry and the flow during a scale-up to different plant sizes and for process engineering description of the cycloid combustion system. 48-3

Numerical Modeling of Moist, Shrinking Biomass in a Deep, Fixed Bed

Combustor

Mathew J. Hagge, Kenneth M. Bryden, Iowa State University, USA

A computational model is used to predict the performance of a deep, fixed bed combustor/gasifier. The combustor/gasifier is the heat source for a proposed steam-driven electric power plant utilizing whole trees as the source of fuel. In the simulation model presented, hardwood logs 20 cm in diameter are burned in a 3.7 m deep fuel bed. Solid and gas velocity and CO, CO2, H2O, hydrocarbon, tar, and O2 profiles are calculated. This simulation couples the packed bed analysis to a high fidelity model for wood pyrolysis. This high fidelity model incorporates full coupling between the drying region, pyrolysis region, and char combustion, and accounts for drying and recondensation within the wood, as well as shrinkage of the solid matrix due to drying and pyrolysis. Wood pyrolysis kinetics, including tar decomposition, are modeled using three competing primary reactions and two secondary reactions. Seven gas phase species and three homogeneous reactions are included. The deep bed combustor obtains high energy release rates per unit area due to the high air inlet velocity and the extended reaction zone. An oxidation region is present in the lowest portion of the bed while the remainder of the bed serves as a gasification and drying region. The wood consumption rate of the computational model is

53

compared with test results obtained from full scale testing. The high fidelity model is used to investigate the performance of the combustor under a wide variety of load conditions, fuel sizes, fuel types, and moisture contents. Extension of this simulation to biomass co-firing is discussed.

SESSION 49

FLUE GAS CLEAN-UP AND SCR/SNCR

49-1

Cleaning of Exhaust Gas by Utilizing Waste Material and Coal

Kenji Kamei, Hideo Funasaka, Center for Coal Utilization, JAPAN

Recently activated carbon attracts much attention because of its capability to absorb mercury and dioxins, however, it is not so available because of its high price. By feeding sewerage sludge and coal, and by aiming at moderate quality and a disposable type, we are trying to manufacture low-priced activated carbon. We will report on the devices and adsorption characteristics of the manufactured activated carbon with respect to dioxin, mercury, and other chemicals through field tests and laboratory tests.Activated carbon powder is sprayed into stacks or pre-coated on bags of a baghouse. Incorporation of dioxin-decomposing function into activated carbon furnace will further promote clean utilization of combustible wastes. 1. Test results of activated carbon manufacturing from sewerage and coal 1) Properties of activated carbon made from mixture of coal and sewerage showed values of the middle when tested alone respectively. 2) Micro pore distribution of the activated carbon manufactured by outer heating screw type furnace is larger than that manufactured by cyclone type furnace or those on the market. 3) In spite of the small adsorption area of the manufactured activated carbon, the activated carbon showed rapid adsorption and this indicates that it suits for spray-removal of toxic gases. 4) The water necessary for the activation was supplied from the sewerage, the system does not require steam generators any more. 4) Coal particles with smaller size distribution showed faster activation speed, thus feed of a mixture of smaller size coal with sludge results in broader adsorption area. 2. Adsorption test results Adsorption tests on actual exhaust gas from an incinerator were carried out. The activated carbon powder was sprayed into the stream through the duct. 1) Dioxin and mercury were removed from the exhaust gas about 80% and 90% respectively. 2) Through make gas tests with pre-coated baghouse simulation, activated carbon from a mixture of fine coal particle and sewerage removed 90% SOx and 30% NOx when ammonia gas was injected at the upstream. 49-2

The Use of Fabric Filters on Low Sulphur Coals

Peter Heeley, Pacific Power International, AUSTRALIA

Australian sub-bituminous coals used for power generation generally have a low sulphur content. While advantageous from a SOx production perspective such coals present many technical difficulties for particulate collection technologies. Traditional approaches using electrostatic precipitation proved to be uneconomic as modern environmental standards were introduced which required reductions in particulate emissions during the 1970’s. The then new technology of fabric filtration was adopted from that time, to achieve best practice emission levels, and in fact “clear stacks.” The use and development of fabric filters for particulate emission control in coal fired power plants in Australia since the 1970’s is discussed. Operating history and performance of the technology, on over 10,000 MW of installed capacity is considered. The adoption of the technology by other countries using coals of similar characteristics is reviewed, and the future potential considered. Relative economics of the technology is considered, compared to other dust collection options. The evolution and usage of fibres and fabrics is described, and the development and history of the different cleaning technologies reported. The importance of bag life as a determinant of economics is reviewed, and current experience of bag life reported.

49-3

The Sulfur Retention Effects of Ca-Based Additives and their Influences on NO Remission During Coal Combustion

Rengui Guan, Wen Li, Baoqing Li, State Key Laboratory of Coal Conversion, P.

R. CHINA A demineralized coal with Ca-based additives was combusted in a quartz tube reactor. The emission of SO2 and NO was investigated under different conditions. The results indicated that the different kinds of Ca-based reagents and their adding methods showed remarkable influence on sulfur retention and gave different effects on retention of organic and inorganic sulfur. The Ca-based reagents also influenced the NO emission. The NO emission changed complicatedly with different Ca-based reagents. Commonly, the Ca-based regents had opposite action on NO formation. They could catalyze the NO reduction reaction to lower its concentration under reducing circumstances, while they could improve the NO formation under oxidizing atmospheres. The effect of Ca-based additive on NO emission was also influenced by the reaction conditions such as temperature and the SO2 concentration. 49-4

Numerical Simulation of SNCR Process for NO Reduction

Dong-Soon Jang, Shin Jang, Mi-Soo Hey-Suk, Kim Hey-Suk, Chungnam

National University, KOREA The purpose of this study is to predict the turbulent reaction with various SNCR processes. The computer program developed is applied to various cases of 2-D and 3-D geometries. In practical systems NOx reduction efficiency by SNCR are strongly dependent on three factors such as turbulence mixing, optimal temperature range and proper reaction time for chemical kinetics after turbulent mixing. For the development of computer program, a control-volume based finite-difference method is used with the Patankar’s SIMPLE algorithm. A two-equation k-ε and RNG k- ε turbulence model is incorporated for the Reynolds stresses and eddy breakup. Turbulence reactions are incorporated using modified conventional fast chemistry models for the NO reaction process with reducing agents, considering a simple overall chemical balance equation. The generation of NO species is described using empirical expression. The calculation of droplet trajectory of aqueous reducing agents is considered in a Lagrangian frame. A series of parametric investigation is performed with combustor type and geometries such as length and the existence of baffle, flow condition of injection velocity and location, the type and injection condition of reducing agents (NH3,,CO(NH2)2). The calculation results shows reasonable and consistent data for the major and minor species and temperature profiles for the 2-D axi-symmetric hypothetical combustor. Further it suggests that the residence time can be substantially increased by flow modification by the baffles mounted vertically on the wall in afterburning region. It was felt to provide enough time even for the NO destruction of the case small combustor. In the case of 3-D industrial boiler and incinerator, special emphasis is given on the investigation of the turbulent mixing of reducing agent injection, considering the amount of flue gas, injecting momentum of deflected reducing jet, together with droplet size distribution. Comparison is made successfully against experimental temperature profile with boiler load. Calculation results indicate that the initial mixing pattern of reducing agents is determined by characteristics of the deflected jet and droplet size distribution is critical to the overall performance of SNCR process. 49-5

On the Mechanism of NOx Reduction by Iron Promoter in Reburning,

Vitali V. Lissianski

Peter M. Maly, Vladimir M. Zamansky, GE Energy and Environmental Research Corporation (GE-EER), Noel L. Benedict, Wyman D. Clark, EER GC,

USA, Andrei Starikovskii, Moscow Institute of Physics and Technology, RUSSIA

Recent research has identified a new process of NOx reduction through the injection of iron particles into the main combustion zone or reburning zone of a boiler. Several additives (Fe metal, Fe2 O3 , Fe3 O4 , and iron oxide waste) demonstrated significant promotion of NOx control in reburning. The process provides high-level NOx control while retaining the cost-effectiveness of reburning and not generating any toxic byproducts. Iron compounds are nontoxic and nonhazardous, and are not expected to significantly affect ash disposal practices. There are several technical challenges that need to be addressed before commercialization of this technology. The mechanism of NOx

54

reduction in the presence of Fe-containing compounds is not well understood. Analysis of experimental data and modeling suggested that NOx reduction occurred via heterogeneous reactions on the surface of Fe-containing particles. However, rates of these reactions are not known. These rates and the mechanism of NOx reduction are the main factors that determine the optimum location of iron injection. Other process parameters to be optimized include the amount and the form of the iron agent and particle size. This paper describes experimental and modeling studies directed at a better understanding of the mechanism of NOx reduction by iron-promoted reburning, i.e., by injection of iron-containing compounds in the reburning zone of a boiler. Particularly, the work is focused on evaluation of the heterogeneous mechanism of NO reduction on the surface of Fe2 O3 particles via reactions 3NO + 2Fe(s) ® 1.5N2 + Fe2 O3 (s) and 3CO + Fe2 O3 (s) + ® 3CO2 + 2Fe(s). Kinetic modeling, as well as laboratory- and pilot-scale tests were conducted. Flow tube laboratory experiments provided information necessary to understand the mechanism of NOx reduction. Pilot-scale boiler tests provided further verification of the mechanism. This information was used to develop a model of the iron-promoted reburning process. Flow tube tests demonstrated up to 90% NO reduction over metallic iron surface without CO. In the presence of CO, it was oxidized to CO2 over Fe2 O3 surface. Comparison of NO concentration profiles measured in a 300 kW combustor in unpromoted and promoted reburning suggested that additional NOx reduction in the presence of Fe2 O3 occurred in the reburning zone while reactions in the burnout zone were not affected by the promoter. The promotional effect increased with an increase in the residence time in the reburning zone. Modeling of the effect of Fe2 O3 on NOx reduction was done under assumption that the rate of NO –Fe interaction is not limited by the diffusion rate of NO to the particles surface. Results of this study confirm that the heterogeneous mechanism of NO reduction on the surface of Fe/ Fe2 O3 particles can be used to describe promoted reburning.

SESSION 50

SYNTHESIS GAS UTILIZATION-II

50-1

Skeletal Iron Catalyst for Syngas Conversion to Ultra-Clean Liquid Fuels

Yijun Lu, Peizheng Zhou, Hydrocarbon Technologies, Inc., USA

An important synthesis gas conversion technology for making ultra-clean liquid fuels, Slurry-Phase Fischer-Tropsch (F-T) process, while using relatively inexpensive iron-based supported catalysts, has encountered problems related to catalyst breakdown to extremely fine particles. That resulted in difficulties in separating the catalyst fines, mostly sub-micron sized, from wax products. Skeletal catalysts have been used for low-temperature, usually liquid-phase, hydrogenation reactions. Hydrocarbon Technologies, Inc. (HTI) has been developing a skeletal iron catalyst for use in Slurry-Phase F-T process for the first time, with objectives of resolving catalyst/wax separation problems by improving catalyst mechanical strength substantially to alleviate breakdown under severe hydraulic conditions in slurry-phase F-T reactors and to facilitate catalyst/wax separation by simple gravity settling. HTI skeletal-iron catalyst (patent pending) is prepared using a specific procedure starting from an iron alloy followed by extraction of inert component, drying and activation under specified conditions. Screening tests and parametric studies on preparation steps and optimization of catalyst composition including major constituent iron and promoters such as Mn, Zn, Cu, K, etc. as well as methods for promoter incorporation have been conducted. Tests showed that catalyst breakdown of HTI skeletal iron is much less than supported iron catalysts, while separation of spent catalyst from wax products is dramatically facilitated and can be realized simply by gravity settling. Synthesis gas conversion activity and product selectivity of HTI skeletal iron catalysts prepared so far have been comparable to those of supported iron catalysts. A 500-hr continuous testing in a 1-L slurry reactor showed no significant activity loss by the end of run. 50-2

Formation of Carbon Nano-Capsules During Rapid Pyrolysis and

Subsequent Steam Gasification of Brown Coal

Kayoko Morishita, Jun-ichiro Hayashi, Kumiko Hatakeyama, Tadatoshi Chiba, Chirag Sathe, Hokkaido University, JAPAN, Chun-Zhu Li, Monash University,

AUSTRALIA

Characteristics of rapid pyrolysis and subsequent steam gasification of Victorian brown coals have been investigated using a novel drop-tube/fixed-bed reactor that consists of concentric double tubes. In each experimental run, a small amount of coal particles was blown onto the filter at the bottom of the inner

reactor tube and rapidly pyrolyzed thereon under a forced flow of nitrogen/steam (47/53 in vol.) through the filter. Volatiles formed by the pyrolysis were immediately swept away of the vicinity of char particles, which were exposed to steam for prescribed period at temperature from 1123 to 1223 K. The gasification of char commenced immediately after the devolatilization that completed within a few seconds, and proceeded very rapidly with specific rate of 0.01 - 0.04 1/s at 1173 K. Such rapid gasification resulted in ca. 80% of carbon conversion of char at reaction time of 100 - 300 s, at which its rate decreased drastically leaving residue with much less reactivity than the initial char and specific rate of 0.0001 - 0.0004 1/s. From the rate analysis based on a kinetic model, the fractional amount of such refractory material was estimated as 10 - 15% on a coal carbon basis. TEM observation of residues after gasification for 1200 - 3600 s identified the refractory material as a type of graphitic carbon, which consists of particles having morphology distinct from those of soot particles derived from volatiles. The particles were hollow spheres (termed carbon nano-capsules, CNC’s) with diameters of 10 - 20 nm and graphene layers’ thickness of 3 - 5 nm. The formation of CNC’s from volatiles is unlikely from minimized contact of volatiles with char surface within the reactor, and hence they may be formed from char. CNC’s were also found within char on the initial stage of gasification and even that formed by pyrolysis in the presence of steam. Inherent metallic species may not be involved in CNC formation, since no metallic species were detected within/on CNC’s, and in addition, CNC’s were formed in the gasification of char from acid-washed coal that contained undetectable amounts of organically-bound metallic species such as Ca, Mg, Na, and Fe. 50-3

Fischer-Tropsch Synthesis: Influence of Process Parameters on Activity

and Selectivity of a Potassium Promoted Iron Catalyst Introduction

Mingsheng Luo, Ari Geertsema and Burtron H. Davis, University of Kentucky, CAER, USA

The work at the CAER has focused on the development of a family of iron catalysts with different alpha values with the objective of providing the option of producing a broad slate of fuel and chemical products. To make a valid comparison of iron and cobalt catalysts with respect to activity and selectivity, the conversions have been carried out over wide ranges of operating conditions including pressure, temperature, H2/CO ratios, diluent gases (both inert and reactive) and conversion levels. As an approach to define the extent of secondary reactions in determining the products that are produced, a variety of isotopically labeled olefins, alcohols and carbon dioxide have been utilized. The extent of incorporation of theses compounds can be defined by determining the isotopic distribution in the products. Catalyst samples, withdrawn from the reactor during synthesis, have been characterized to define changes that occur during catalyst use. 50-4

Scale-Up for Fischer-Tropsch Synthesis over Iron-Manganese Catalyst

Yong Yang, Hongwei Xiang, Yuanyuan Xu, Yongwang Li, Bing Zhong,

Chinese Academy of Sciences, P. R. CHINA

An ultrafine iron-manganese catalyst for Fischer-Tropsch synthesis was prepared by the controlled degradation method. Its reaction performance was evaluated in various reaction conditions (T=553-593K, P=1.0-2.5MPa, GHSV=500-2000h-1, H2/CO=0.67-3.0) with a 5-mL fixed-bed reactor, which showed that the catalyst had high activity, and high selectivity to low molecular olefins. A new concept was proposed, i.e. the first-stage transformed syngas derived from coal and natural gas to low molecular olefins and liquid hydrocarbons over Fe-Mn catalyst via Fischer-Tropsch synthesis, and the second-stage converted low molecular olefins and liquid hydrocarbons to gasoline product over ZSM-5 zeolite via selective reforming and olefin oligomerization. A series of scale-up tests were carried out in the two-stage fixed bed reactors with tail-gas recycling to effectively restrain the formation of CO2 and improve the selectivity of hydrocarbons, including 100mL fixed bed reactor, 1L fixed bed reactor and 5L industrial single-tube tests. The industrial single-tube test for 3000h showed that CO conversion was about 95%, hydrocarbon selectivity was above 90%, and gasoline (C5-C11) yield exceeded 124g/NM3(CO+H2). The first-stage reaction was carried out at 553-593K, 2.5MPa, GHSV:400~550h-1 and H2/CO ratio:1.8~2.1. The second-stage reaction conditions were 553~623K, 2.5MPa. The tail-gas recirculation ratio of the process was 3~4. The octane rate of the produced gasoline was 90.1. The new process for synthesis of gasoline by F-T reaction showed promising for the commercial application of large-scale coal-based synfuel.

55

50-5

Ruthenium Modified Co/ZrO2-SiO2 Catalyst to Synthesize Long–Chain Hydrocarbons

Gao Haiyan, Yang Wenshu, Xiang Hongwei, Li Yongwang, Sun Yuhan,

Chinese Academy of Sciences, P. R. CHINA

In our previous work, a Co/ZrO2-SiO2 catalyst[1] for Fischer-Tropsch synthesis(FTS), which showed good catalytic properties, was developed. As a continuing part of the series efforts, this report is devoted to examine the effect of Ru as a promoter for Co/ZrO2-SiO2 catalyst. The Co(18wt%)-Ru/ZrO2-SiO2 systems with various contents of Ru ( from 0.0 to 10.0 wt%) as compared to Ru(10wt%)/ZrO2-SiO2 catalyst have been prepared. And a fixed bed reactor is employed to investigate their catalytic performance with the following conditions: T=463-493K, P=2.0MPa, GHSV=500h-1, H2/CO=2.0.The results show that addition of proper amount of Ru lowers the methane selectivity and raises C5+ selectivity, but excessive amount of Ru added leads to opposite results. With the increase of Ru loading, the olefin to paraffin ratio increases. Various characterization methods such as TPR, XRD, XAFS are also used to determine the physical and chemical properties of the catalysts. TPR results show that the Ru addition facilitates reduction of Co-Ru/ZrO2-SiO2, leading to catalysts with higher reducibility. XRD tests indicate that Ru addition results in smaller crystallite size. According to XAFS results, a large fraction of the Ru remains exposed, suggesting that Co-Ru particles prefer a configuration where most of the Ru in reduced samples lies near outer crystallite surfaces. 50-6

A Heterogeneous Reactor Model for Fixed-Bed Fischer-Tropsch Synthesis

Yi-Ning Wang, Yong-Wang Li, Xu Yuan-Yuan, Yu-Long Zhao, Bi-Jiang

Zhang, Chinese Academy of Sciences, P. R. CHINA

Fischer-Tropsch synthesis (FTS) converts syngas into a wide product spectrum consisting of a complex multi-component mixture of linear & branched hydrocarbons and oxygenated products. From the viewpoint of economic viability the selectivity considerations are extremely important in the development of a Fischer-Tropsch process. To achieve an optimum performance for the complete process, the catalyst and the reactor should be comprehensively optimized. Evidently, due to the highly complexity of FTS reaction system, the proper establishment of heterogeneous reactor model, which can reflect selectivity information as well as heat-transfer information, is of vital importance. To realize a more comprehensive description of fixed-bed Fischer-Tropsch reactor, several challenges should be faced. The first is how to establish a detailed mechanistic kinetics model accounting for FTS intrinsic polymerization kinetics performance. The second is how to treat properly the phenomena that the FTS catalyst pores are filled by waxy products in realistic gas-solid reaction process. In our previous efforts, the detailed kinetics model, the generalized gas-wax equilibrium correlation, and the diffusion-reaction model for wax-filled pellet, were systematically constructed. Based on these preliminary models, a heterogeneous reactor model for FTS is presented in this paper. By using this reactor model, the overall reaction behavior at reactor level and the detailed diffusion-reaction behavior at pellet level are further discussed.

SESSION 51

COAL COMBUSTION BYPRODUCTS UTILIZATION-IV

51-1

A Case Study on Use of Coal Fly Ash for Reclaiming a Surface Coal Mine Pit

Ishwar P. Murarka, Ish, Inc., USA

The United States of America mines coal by surface and underground mining methods. Over 600 million tons of coal are combusted in utility boilers to generate electricity. Over 105 million tons of coal combustion byproducts (CCBs) are generated annually by these power plants. Only a small amount of the CCBs are utilized in backfilling or reclaiming the coal mined areas. Deposition of CCBs in mined lands can serve two purposes offering large environmental and social benefits. The first purpose of CCB placement in mines is to reclaim mined land for productive land use in an economic and environmentally sound manner. The second purpose of using CCBs in mine filling is to eliminate the need for converting lands near power plants to landfills and impoundments. However, perceptions and lack of reliable scientific data continue to create large obstacles in increasing or even retaining the current use

of CCBs in active and inactive mines. Several million tons of CCBs can be beneficially used in mine-filling operations on an annual basis. In a regulatory determination on May 22, 2000, U.S. EPA decided that the Agency will establish national regulations under Subtitle D of RCRA and/or upgrade SMCRA controls for coal combustion wastes used to fill surface or underground mines to ensure protection of human health and the environment. EPA specifically noted that it has considerable concern about certain current practices, e.g., placement directly into groundwater. Ish Inc. is carrying out a research project funded by U.S. DOE, Cinergy, EPRI, and ACAA to conduct field and laboratory studies on the environmental processes and effects associated with the placement of coal fly ash in a surface mine pit in Indiana, U.S.A. Over 1.2 million tons of coal ash from a nearby power plant have been placed at the Universal site to nearly fill the open pit over a ten-year period beginning in 1989. The coal ash is placed dry and the final grade consists of a soil cover with grass. Monitoring of groundwater and surface water for approximately 34 parameters has been performed quarterly for the past 10 years at several locations at the site. Data have also been collected on the bulk chemical composition and laboratory generated leachates for the CCBs on a quarterly basis. The coal ash is alkaline and has a pH of about 9.0. Earlier this year as a part of this research project, additional groundwater monitoring wells have been installed at the site. Several cores have been collected to carry out laboratory experiments to study the environmental chemistry of a number of metals and to examine the neutralization chemistry at the site. Acid mine drainage (AMD) was present at the Universal ash site due to the exposure and oxidation of pyrite in coal. One of the monitoring locations at the Universal site is the water from mine seep located about 800 ft downgradient of the ash-fill area. The monitoring data show significant improvements in the water quality of the mine seep and include near elimination of acidity; neutralization of pH, and reduction in iron, manganese, and sulfate. However, these monitoring data also show an increase in boron concentrations in the mine seep water. Time series data plots and trends have been utilized to identify these changes in water quality. 51-2

Utilization of CCPs for AMD Abatement During Re-Mining of an

Abandoned Underground Mine

Mary W. Stoertz, Ben J. Stuart, Ohio University, Gary Novak, Ohio Department of Natural Resources, USA

Re-mining of abandoned room-and-pillar coal mines has the benefit of recovering an energy reserve not usually accessible because of the mines. The hidden dangers of abandoned underground mines during re-mining include mine gases, unstable roofs and highwalls, and volumes of acid water. Re-mining can help mitigate the acid mine drainage (AMD) problem by exposure of the AMD source and dewatering of the mine complex. Additionally, re-mining allows for placement of a continuous hydraulic mine seal effective for multiple openings and entries. Re-mining of coal reserves in abandoned mines may not be economically feasible for the mining company, however, due to the added AMD responsibilities incurred. This paper presents the planning and completion of re-mining and sealing of an abandoned underground mine complex last mined in 1910 in Coshocton County, Ohio. Re-mining and evaluation is a joint effort among ODNR-DMRM, R&F Coal, and American Electric Power. Part of the project includes a controlled evaluation of re-mining and sealing with CCPs as a tool for restoration of abandoned mine lands and AMD abatement. Fixated flue-gas desulfurization (FGD) by-product was selected as the material used for the mine seal for several reasons. First, FGD has a low hydraulic conductivity, which limits seepage of waters from the underground mine. The hydraulic conductivity decreases with time as the material cures. Second, FGD possesses a high alkalinity that can neutralize acidic seepage that occurs. Finally, the material is in abundant supply from a facility located near the mine. Beneficial use of the by-product diverts a fraction of the material that is otherwise placed in a landfill. Pre- and post-mining water quality indicates the effectiveness of the re-mining and sealing. Water levels monitored at 14 wells indicate mine inundation occurred within 12 months of the completion of the seal. Cyclical water level fluctuations occur with wet/dry seasons. Water quality has improved inside the mine and exhibits some of the cyclical seasonal changes in quality. Seepage quantities have been reduced by 50% and contaminant loads to the watershed have been reduced up to 97% for certain targeted water quality indicators. 51-3

Evaluation of Fly Ash as a Soil Amendment for Horticulture on Sandy Soils

S.M. Pathan, L. A. G. Aylmore, T. D. Colmer, The University of Western

Australia, AUSTRALIA

56

Fly ash is the fine residue captured from flue exhausts when coal is burnt in power stations. Fly ash incorporation into sandy soils may improve water and nutrient retention, with potential to increase plant productivity and also reduce the problem of nutrient leaching. A series of physical and chemical analyses were undertaken to characterise fly ash samples taken from power stations at Kwinana and Muja in Western Australia, and Tarong, Callide and Gladstone in eastern Australia. Three fly ash types from Kwinana were evaluated: 3 year old ash from a stock pile, 3 month old ash from a stockpile, undiluted ash from a hopper. All other samples of fly ash were taken undiluted from a hopper at the various power stations. The three different aged samples from Kwinana were taken in order to evaluate the effects of the slurry process and weathering in the stockpile on the properties. Soils from the Spearwood and Bassendean dune systems of the Swan Coastal Plain were also subjected to the same analyses. A large proportion of horticulture in Western Australia is located on these sandy soils, so these are potential targets for soil amendment technologies. The results of the physical and chemical characterisation show considerable differences between the soils and fly ashes, but also variation in several properties among the fly ashes. Soils were comprised primarily of coarse sand-sized particles and most of the fly ashes were comprised primarily of fine sand-, silt- and clay-sized particles. Fly ash from Tarong however, was coarser than the other fly ashes. Specific surface areas of fly ash from Western Australia were 10-25-fold higher than for those from eastern Australia. The hydraulic conductivities of fly ashes were 200-400 times slower than the two coarse sands. The water holding capacities of fly ashes at “field capacity” were 3 times higher than those of the two sandy soils. Water holding capacity increased progressively with larger additions of fly ash to the soil, with substantial improvements in plant available water in these substrates. In comparison with the sandy soils from the Swan Coastal Plain, the extractable P and PRI in the fly ashes were high except for samples from Tarong and Callide. There was considerable variation among the fly ashes for EC and pH, with samples from Muja the most acidic (pH=3.84; 1:5 in CaCl2 extract) and from Gladstone the most alkaline (pH=9.90). EC was high in the undiluted Kwinana fly ash, but much lower in samples from the stockpile. Possible release of heavy metals from all sources of fly ashes were evaluated using the toxicity characteristic leaching procedure; values obtained for all heavy metals tested were well below the regulatory guidelines as set by the US EPA. The influence of these properties on the potential to use the various sources of fly ash as soil amendments will be discussed. 51-4

Impact of Chemical Weathering on Leaching from Coal Fly Ash:

Identification of Natural Weathering Reactions

Kevin H. Gardner, Robert Carter, University of New Hampshire, USA

It has been observed that waste materials from high-temperature processes are thermodynamically unstable in the natural environment and weather in a similar fashion to volcanic ash, although many times at a faster rate. Experiments were conducted with a variety of waste materials to accelerate the individual mechanisms involved in the geochemical transformation process (dissolution, precipitation, carbonation and pH reduction), and pH-dependent leaching experiments were used to characterize changes in the availability of heavy metals in the weathered materials. Mechanisms investigated for decreased heavy metal availability include increases in exchange capacity and substitution of heavy metals in newly formed mineral phases. Analytical techniques employed in this study include transmission electron microscopy, neutron activation analysis and x-ray diffraction. Results from coal fly ash investigations will be presented. 51-5

Characterization of Dry Flue Gas Desulfurization By-Products for

Hydraulic Placement in Underground Mines

Nader Ghafoori, Tennessee Technological University, Bradley Paul, Southern Illinois University at Carbondale, USA

Underground mine subsidence effects over 600,000 acres of land in the U.S. Midwest, damaging houses, schools, roadways, and infrastructure. Conventional backfilling can cost on the order of $60/yd3 of material placed, making stabilization of underground excavations feasible for only the most crucial cases of potential damage. Over 20 million tons of flue gas desulfurization by-products are produced in the U.S. every year and only about 2% are ever used. A study was done under sponsorship from the U.S. Department of Energy to find ways to utilize surplus coal combustion byproducts to produce hydraulic mixes capable of filling underground voids at

much lower cost. Because many mines impacting communities are shallow, it is important that mixtures having adequate strength also have suitable leachate properties to be utilized in contact with productive groundwater resources. This paper familiarizes readers with the physico-chemical properties, fresh and hardened characteristics (workability, consistency, heat of reactions, unit weight, and compressive strength), and leachate concentrations and hydraulic conductivity of different composites made with Flue Gas Desulfurization (FGD) scrubber sludge and Pulverized Coal Combustion (PCC) fly ash. They were evaluated to ascertain their suitability for hydraulic placement in underground mines. Four different matrix proportions were prepared, under gravity placement at three distinct moisture conditions, and cured in a curing chamber designed to simulate mine conditions (temperature of 90± 10 oF and relative humidity of 90± 10%). Test results conclude that the heat of reaction was unaffected by the change in the matrix proportions and remained in the range seen for class “F” fly ash mixtures. The unit weight of the hardened specimens decreased with an increase in the scrubber sludge content of the mix. The pocket penetrometer index increased as the fly ash content of the matrix increased. Although strength properties improved with increases in fly ash content, the trial matrices displayed low strength values attributed to the lack of densification effect, delayed cementitious reactions of fly ash in the absence of a catalyst, and potential matrix retardation induced by scrubber sludge. ASTM column tests revealed few elements of concern with either the components or the matrices themselves. The most pronounced metals in the leachates were alkali metals such as calcium. Boron was also seen in the leachate but was less pronounced when larger concentrations of scrubber byproduct were used. Calcium leaching was persistent but boron leaching was not. Limited hydraulic conductivity relative to near surface aquifer units suggested that leachate production would be inadequate to create environmental problems due to dilution alone.

POSTER SESSION-1

COAL GEOSCIENCES & RESOURCES

P1-1

Utilisation of the Environmental Scanning Electron Microscope (ESEM) in the Study of Coke and Coking

Basim Faraj, Faraj Consultants Pty Ltd., Grant Quinn, International Coal

Consulting (ICC) Pty Ltd, R. Calcott, Tom Callcott,Callcott Consulting Pty Ltd, AUSTRALIA

The development of the Environmental Scanning Electron Microscope (ESEM) adds a new and important dimension to electron microscopy. Conventional SEM requires a vacuum while the (ESEM) allows direct examination of unprepared samples under atmospheric pressure and different gaseous environments and temperature regimes. This includes dynamic experiments such as wetting, drying, heating, cooling and melting which could not previously be performed under the scanning electron microscope. This paper reports for the first time the use of ESEM for experiments on coal and coke samples. In one experiment, samples of coke were subjected to similar conditions to the Nippon Steel Corporation’s coke reactivity test (CRI). Following on from that work, a research project was funded by the Australian Coal Association Research Program (ACARP) to investigate the behaviour of minerals in coke under blast furnace conditions simulated in the ESEM. The findings are encouraging and demonstrate the use of this new technology to investigate old problems. P1-2

New Aspects in Sequence Stratigraphy: Lowstand Cycles and Coal

Formation in Paralic Environment

Norbert Volkmann, Freiberg University of Mining and Technology, Gerda Standke, Saxonian State Agency for Environment and Geology, Jochen Rascher,

GEOmontan Entp. Freiberg, GERMANY

Most of the world coal resources were formed in a paralic paleoenvironmental setting. That means its origin is strongly related to sea level fluctuations. Previous studies about the formation of paralic bogs focused only on their high stand periods after transgressive sea-level event. In contrast to this view, the deposition of the 2nd Miocene Seam of the Lusatian Brown Coal District (East Germany) is interpreted to have taken place during a regressive sea-level cycle. This conclusion was mainly enabled by the increasing abundance of factual material, observations, samples and raw data from numerous outcrops. The outcrop density rapidly increased during the last 25 years due to exploration and production works (open cast pits and thousands of wells).

57

The 2nd Miocene seam was studied on area covering more than 10.000 sq. km (approx. 3.860 sq. mi). This is mostly determined by its paleogeographic position at the southern shelf margin of the North-West European Tertiary Basin. The interpretation of 6.000 - 7.000 of geophysical well-logs resulted in a detailed knowledge of very fine-scaled lithofacial changes within the layers and helped to construct an improved model of the sedimentation during the Lusatian Tertiary. Palynological investigations supported the identification of the sedimentary units and made it possible to correlate sequences of the Lusatian Miocene with the biozonation of the marine basinal centre. In addition, detailed macro- and micropetrographic studies of the coal seam combined with micropalaeontological analysis (dispersed cuticules) led to the recognition of the characteristic, rhythmic bogfacial successions and to the reconstruction of paleogeography during peat formation. All it shows, that during lowstands of sea-level preconditions for the repeatedly formation of large peat bogs were given. Accordingly, the formation of important seams was mainly controlled by small-scale sea-level fluctuations and the intensity of alluvial accretion in a coastal-deltaic environment not only during transgressive but in regressive periods also. P1-3

The Phasing Out of Mining Industry and Technical and Economical

Aspects of Large – Volume Wastes Deposition in Closed Mines

Jaroslav Dvorácek, Vladimír Slivka, VŠB – Technical University of Ostrava, Jiří Štěrba, Geoconsult Karlovy Vary, CZECH REPUBLIC

The production of the Czech Republic’s coal industry has decreased approximately to a half during last ten years. The closed underground mines represent now a serious threat to the environment and safety of persons and property due to surface depressions, gas escapes and the releasing of mineralised waters. In the town built-up area in the centre of the Czech Republic’s largest hard coal district, some cases of gas escape, necessary inhabitant evacuation and gas explosion connected with personal injuries have occurred. The contribution deals with solving the problem of large-volume industrial waste stowing in the underground spaces of abandoned mines. The fact that nowadays the large-volume industrial wastes form more than 80% of the total volume of wastes produced in the Czech Republic plays an important role. The idea rests upon the utilisation of wastes as secondary raw materials for the production of mine building and reclamation-remediation materials. The basic criterion for the selection of wastes suitable for use as secondary raw materials in the production of mine building materials is the assessment of their hazardous properties. The following items belong to them: ecotoxicity, subsequent hazardousness, late effect, causticity and radioactivity. Hydraulic stowing mixtures are evaluated from the point of view of environmental impacts, transport technology and underground deposition. The economical aspect of these activities is taken into account as well. P1-4

Lignite-Water Interactions

Tham Vu, Alan Chaffee, Monash University, Irene Yarovsky, RMIT University, AUSTRALIA

The high moisture content of Victorian lignite (60-70%) is a major disadvantage, limiting the efficient use of this fuel as a source for power

generation. Prior to combustion, the moisture is removed evaporatively, leading to direct loss of latent heat of evaporation. This work aims to provide an improved understanding of lignite-water interactions, with a view to assisting

the development of more efficient drying technologies. A thorough understanding of water adsorption, binding and desorption in the lignite matrix is sought, together with some knowledge of the lignite chemical structure. Formed from a vast array of altered plant remains, lignite has an exceptionally complex physical and chemical structure. This complexity renders lignite, as a bulk material, very difficult to study by conventional chemical methods. Fortunately, the structure of lignite incorporates many structural features of the dominant plant precursors thus if the focus is directed at the lignite constituents rather than the entire lignite, this complexity can be reduced. Lignin, a constituent of wood, is highly preserved at the lignitic stage. In this study, we focus on the interactions between lignin and water as an approach to understanding lignite-water interactions. FTIR-and 13C Solid-state NMR spectroscopy and cation exchange are used to investigate the chemical structure while helium pycnometry, mercury porosimetry and CO2 surface area are used to probe the physical structure of lignin. Lignin-water interactions are explored with sorption isotherms and molecular modeling. P1-5

Bituminous Coal Seams Burning Out – Mathematical Model

Zdeněk Klika, Tomáš Kozubek, Zdeněk Dostál, VŠB-Technical University Ostrava, Dalibor Dvořák, Ostrava University, CZECH REPUBLIC

Carboniferous variegated beds occur in Czech and Polish parts of the Upper Silesian Coal Basin (USCB). To the west, the boundary of the variegated beds region is mostly limited by the Orlová structure, to the south and to the north by Bludovice and Dětmatrovice wash-out channels, respectively. In these positions there are a lot of tectonic faults on which variegated beds are bonded. Coal seams that enter into variegated bodies in a distance of some meters are completely pinch out. It is supposed that intensive oxidation of coal seams on the paleosurface of Carboniferous mountain in Triassic and Jurassic led to the burning out of coal seams and at the same time to the formation of the weathered rocks mantle (variegated rocks). For the verification of the above theory one variegated body into which three coal seams (No.504,520 and 540) enter, was selected in Lazy Mine. Scheme of this locality is presented in figure.

The process of coal seams burning out was mathematically described using the following 2D heat equation with standard initial and boundary conditions.

( ) ( ) ( )T,t,q~t,T)(t

t,T)()(c xxxxxx =∆λ−

∂∂

ρ ,

Ω∈x , 0>t ,

where )(),(),( xxx λρc are material characteristics, T(x, t) is temperature

in the place x and time t and q~ is the heat source. The boundary of the variegated body was determined as the isotherm 350oC using laboratory experiments. A method of lines semidiscretization together with the finite elements method to descretize this problem was applied. The calculated results and their comparison with data from locality Lazy Mine show a good credibility of suggested model. It gives support to hypothesis of coal seams burning out and variegated body formation at the same time.

58

POSTER SESSION 2 GASIFICATION

P2-1

High-Temperature Interactions Between Coal Char and Mixtures of

Calcium Oxide, Quartz and Kaolinite

Jie Wang, Tohoku University, Kayoko Morishita, Takayuki Takarada, Hokkaido University, JAPAN

There is a scanty of knowledge about the thermal interactions between mineral matter in coal and coal char, although it is important in the understanding of some coal conversion processes. We recently highlighted the reactions between mineral matter and coal char.3 The carbothermal reactions of quartz and kaolinite started at 1200 °C under both Ar and N2 atmospheres, releasing CO. N2, that is generally used as an inert gas, actively participates in the reaction, forming nitrides. In this study, the interaction between coal char and mixtures of calcium oxide, quartz and meta-kaolinite were investigated by heating to 1600 °C under Ar. Calcium oxide was gradually reduced by coal char in the temperature ranging 950-1450 °C, releasing CO. CaO was carbided fast above 1450 °C. As CaO coexisted with meta-kaolinite, CaO reacted with meta-kaolinite below 1200 °C. The SiO2 component in the CaO-SiO2-Al2O3 compound was more readily carbided than the Al2O3 component. By heating to 1600 °C, the presence of a calcium aluminum oxide carbide was notable, indicating that both CaO and Al2O3 became hard to reduce while they were chemically combined. The SiO2 component in CaSiO3 started with carbothermal reduction at 1200 °C in preference of the CaO component, forming SiC and Ca2SiO4; at higher temperature, both components of SiO2 and CaO in Ca2SiO4 were carbided significantly. On the other hand, two demineralized coal chars were found to be graphitized appreciably in the presence of calcium species. Calcium oxide exerted a strong catalytic effect on the graphitization of coal char, mainly forming the graphitic carbon at 1600 °C. As CaO incorporated with meta-kaolinite or quartz, the action of CaO towards the graphitization of coal char weakened, primarily resulting in the turbostratic carbon at 1600 °C P2-2

Reaction Bonded Silicon Carbide Hot Gas Filter

Sang-Whan Park, KIST, Sung-Sik Hwang, Tae-Woo Kim, Kookmin University,

KOREA

The reaction bonded SiC (RBSC) and SiC fiber reinforced RBSC hot gas filter were developed using Si infiltration method for the use in integrated gasfication combined cycle(IGCC) system. It has been known that the low fracture strength and the brittle fracture behavior of ceramic hot gas filter restricted the long term use in hot gas filtration for IGCC system. It was found that mechanical properties of RBSC and SiC fiber reinforced RBSC porous filter were surpassed the performance of currently developed ceramic filter. The fabricated porous RBSC with porosity of 40 vol.% showed the improved fracture strength ( > 50 MPa). Furthermore, the delayed fracture behaviors were observed for SiC fiber reinforced porous RBSC at room temperature and 900oC, which could improved the reliabilities of ceramic hot gas filter significantly. The newly developed fabrication method using Si infiltration could make it possible to fabricate the large scale hot gas filter economically by applying the continuous reaction sintering process. The permeability and thermo-chemical stability of RBSC hot gas filter at elevated temperature under the simulated coal-fired atmosphere were also examined. The results of this study indicate that newly developed RBSC based porous filter could be applied to the hot gas filter in IGCC system due to it’s improved mechanical properties as well as the reduced fabrication cost. P2-3

Preparation and Performance of Activated Carbon Supported Zinc Ferrite

Absorbent for Hot Gas Cleaning

Toshimitsu Suzuki, Hiroaki Matsushima, Na-oki Ikenaga, Kansai University, JAPAN

Efficient and clean utilization of coal is one of the most important tasks for our future sustainable society. For this purpose integrated coal gasification combined cycle (IGCC) or coal gasification fuel cell (IGFC) are promising technologies. In such processes, complete removal of sulfur containing impurities such as hydrogen sulfide at a higher temperature is one of the key technologies.

Zinc ferrite is proposed to be an important absorbent for the hot gas cleaning. However, surface area of zinc ferrite prepared by dry process is not sufficiently high. Therefore absorption rate of H2S is not large. In addition, after surface of the absorbent was sulfided, decreases in the absorption rate of the absorbent was observed. To overcome this, we have developed new type of absorbents which were supported on a porous material. Preparation of ferrite by dry process requires a high temperature and prolonged period. Low temperature ferrite preparation method is also of importance. From these view points, we have tried to synthesize ferrite in the presence of activated carbon. Activated carbon loaded ferrites were made as follows: (i) an aqueous solution of iron and zinc nitrates was impregnated onto activated carbon. (ii) co-precipitation of Zn-Fe mixed solution with ammonia, (iii) with urea at 80 oC (homogeneous precipitation). Dried samples were calcined in an air at 400 to 500 oC, samples were characterized by XRD, BET. H2S absorption behavior was monitored by two methods; using (i) a thermal balance and (ii) a fixed bed flow reactor at 400 to 600 oC. Typical results of absorption of H2S observed by the fixed bed flow system were shown in Table 1.

Table 1 Absorbent prepared and performance of absorption behaviorb

Entry Method Absorbent Prep temp SA Oxide cotent Performance oC m2/g % %b H2S outc 1 ppt Fe2O3 500 40 100 76 20-30 2 Co-ppt ZnFeO4 500 41 100 45 1 3 impregnation ZnFeO4/AC 500 50 96.8 110 <1 4 Co-ppt ZnFeO4/AC 500 463 56.9 80 <1 5 Hom-ppt ZnFeO4/AC 500 317 66.2 105 <1 a)H2S 4000 ppm in Ar+H2+H2S b)Performance indicates % ZnFeO4 transformed into (ZnS + FeS) measured at 400 oC. c)H2S concentration at effluent in ppm As seen in Table 1, except co-precipitated ZnFeO4 (entry 2) ferrite prepared wet process showed high performances in the absorption of H2S. Ferrites prepared with activated carbon exhibited higher performance, as compared to Fe2O3 or bulk ferrite (entry 2). Bulk Fe2O3 afforded considerable absorption performance, but H2S concentration in the effluent was high. This value does not meet IGCC process. Ferrites prepared in the presence of activated carbon exhibited larger surface areas except impregnated one. Ferrite prepared by impregnation method showed a small surface area due to a smaller content of activated carbon. Bulk ZnFeO4 prepared by dry process, exhibited considerable absorption performance, however, rate of absorption is much smaller than those prepared wet processes, as observed by TG. Absorption and regeneration cycles were repeated for the activated carbon loaded ferrites. In the generation stage with air at 460 oC, most of carbon was burnt out. However, absorption of H2S was not affected in these cycles. A large portion of the ferrite was regenerated after oxidation in air, and only a small portion of the ferrite was degraded into Fe2O3 and ZnO. All these results showed that activated carbon loaded ferrites are excellent absorbents for hot gas cleaning. P2-4 Recovery of Hydrogen and Producing Alternate Fuels from Steel Mill Off-

Gas

Yen V. Nguyen, Kinectrics, CANADA

The overall objective of this project is to develop and test technologies that are not currently available to produce hydrogen and paraffinic fuel to replace conventional diesel from steel mill off-gases. There is a significant amount of off-gases being produced from various operations at the integrated steel mill such as from the coke oven, blast furnace and basic oxygen furnace. Most of the gases from the coke oven and blast furnace are being used at the plant for heating purposes, for example, to under-fire the coke oven, pre-heat the air for the blast furnace or generate steam and electricity for the site. A small amount of these gases is being flared due to process conditions. The basic oxygen furnace gas, on the other hand, is entirely flared as it is produced intermittently, difficult to collect and there is little use of the heating value of the gas at the site. These flares are a waste of energy resources, creating an emission issue and causing a significant impact on the environment. There is a need to capture these gases and turn them into more valuable energy resources. In addition, there may be more surplus coke oven gas available in the future from the steel plant as the steel industry continues to restructure and eliminate unprofitable operation which will cut down the need for heating with the coke oven gas in some operations. The surplus gas could be used for power generation, if technology is available, but it is uncertain whether it would be economically attractive in a deregulated electricity market.

59

Therefore, there is a need to develop a process to utilize this gas and turn it into a valuable product as well. This project is to develop processes to utilize the coke oven gas, basic oxygen gas and some blast furnace gas to produce hydrogen and paraffinic fuel to replace conventional diesel, and then conduct testing and demonstration of the technology. Available technologies were reviewed and two conceptual designs were developed to produce either hydrogen or paraffinic fuel from these gases. Heat and mass balances for the conceptual design options to produce the desired products were developed and capital and operating cost were estimated. Results of the analysis indicated that the preferred option to produce hydrogen from steel mill off-gas with less technology uncertainty and risk is by using the pressure swing adsorption technology with the coke oven gas. Hydrogen production cost was estimated to be lower than the market price. The preferred option to produce paraffinic fuel is by using a modified Fisher-Tropsch technology with the basic oxygen furnace gas. However, the capital cost for a plant to produce paraffinic fuel from the basic oxygen furnace gas could be high due to the cost of the gasholder which is needed to store this intermittently produced gas. Other conceptual design option using the blast furnace gas instead will be discussed. Interest from industries and governmental bodies for demonstration of the technologies will be highlighted.

POSTER SESSION 3

PULVERIZED COAL COMBUSTION

P3-1

Development of New Low-Nox Burners for Tangentially Fired Power Plants Using Lignite, Hard Coal And Biomass

Pauli Dernjatin, Fortum Power and Heat Oy, Kati Savolainen, Antti Heinolaine,

Fortum Engineering FINLAND

A new type of low-NOx burner has been developed for NOx reduction of tangentially fired boilers. The basic idea of the RI-JET (Rapid Ignition) low-NOx burner is to create a high-temperature reducing flame near the burner tip. In order to promote rapid ignition and to form a reducing zone near the burner, the RI-JET burner is equipped with a flame stabilizer in the coal nozzle, an axial swirler in the secondary air nozzle and a guide sleeve between the secondary and tertiary air nozzles. At first stage Fortum developed RI-JET 1 burner (NOx = 180 ppm) and at the next stage RI-JET 2 with extremely low NOx (NOx = 45 ppm). This new low-NOx combustion technology has been applied in 16 boilers; two in Finland (100 MWe and 125 MWe) and four in Czech Republic (4*200 MWe), six in Poland (6 * 135 MWe) and four in Romania (4 * 125 MWe). The NOx reductions achieved by RI-JET 1/2 burners and an over-fire air system has been varied between 50 and 80% and, at the same time, unburned carbon has been below 5%. The flame has been stable over the normal load range 50-100%, and the flame stability has been independent of the burner zone stoichiometric ratio. Low NOx and UBC values were therefore achieved also when operating the boiler at low load. According to Fortum’s experience it is now possible to apply circular type burner with high temperature and wide flame (= low NOx) not only to wall firing but also tangentially firing boilers. It is expected that in the near future NOx value 100 ppm (70 mg NO2/MJ) can be achieved with RI-JET 2 burners without catalyst. P3-2

Coal Characterisation: A Review

Atul Bhargava, Raj P. Gupta, Lianguang Tang, Terry F. Wall, CRC for Coal in

Sustainable Development, AUSTRALIA

Coal has been analysed and characterised for more than a century based on its bulk properties ie specific energy, fuel ratio and average vitrinite reflectivity. However, recent restrictions due to greenhouse gas emissions and subsequently a strong competition with other fossil fuels, there has increased pressure on improving the performance of the existing technologies and developing more efficient technologies. Development of mechanistic models for devolatilisation, combustion, gasification and ash formation needs to account for the variation of related properties from particle to particle due to the heterogeneous nature of coal. This review papers looks at different analytical techniques developed over the years including recent advances in characterising coal on a micro scale. These analytical techniques are reviewed in context of characterising coal for specific applications such as coking, combustion and gasification. The application of the data from these advanced techniques in development of advanced predictive models has also been reviewed.

POSTER SESSION 4 LOW-RANK COAL UTILIZATION

P4-1

Solid Residues of Lignite Hydrogenation: News from Petrograpy and NMR

Spectroscopy

Winfried Boehlmann, University of Leipzig, Norbert Volkmann, Freiberg University of Mining and Technology, GERMANY

Fluorescence microscopy as well as 13C-CP/MAS-NMR spectroscopy are applied to characterize hydrogenation residues of lignite lithotypes. The combination of the microscopic and spectroscopic techniques allows a detailed description of the coal decomposition during the liquefaction process under several conditions. Particularly, different decomposition steps in the coal network can be detected by means of the NMR method used. A quantitative component analysis of the hydrogenation residues is performed applying fluorescence microscopy. A new kind of residue component is detected indicating mild hydrogenation conditions for lignites. Furthermore, the conversion of the lignite macerals under different hydrogenation conditions is studied to obtain information on the formation of typical residue constituents. Although the techniques applied deviate strongly it is possible to demonstrate the influence of typical liquefaction conditions, such as hydrogen deficiency or reaction temperature, as well as in the petrographic and in the spectroscopic results. While the 13C CP/MAS NMR allows a quantitative analysis of the remaining organic matter of the coals the fluorescence microscopy confirms the formation of typical components showing dependence on hydrogenation conditions. P4-2

Fundamental Characteristics on Co-Combustion of Low-Rank Coal with Biomass

Ichiro Naruse, Asri Gani, Keiju Morishita, Toyohashi University of Technology,

JAPAN

In order to utilize low-rank coals efficiently and cleanly, co-combustion of the coal with biomass was proposed since the biomass had the function to enhance the overall reaction characteristics. In this study, the co-combustion was tested, using an electrically heated drop tube furnace, to elucidate effect of the biomass on the combustion characteristics and NOx (NO and N2O) emission from coal. Three types of coal with different content of volatile matter and sawdust were used as coal and biomass samples, respectively. The mixing ratio of coal to biomass was 1 to 1 as the mass basis. The total heat load and the combustion stoichiometry were kept almost constant in all the experiments. The combustion and NOx behaviors under the co-combustion condition were compared with those under the coal or biomass combustion condition. As a result, when the coal with low volatile content was burned alone, the ignition was delayed, and the combustion efficiency was quite low. Under the co-combustion condition of its coal with the biomass, however, the ignition took place at the upper stream of the furnace, and the combustion characteristics seemed to be better. This suggests that the biomass can enhance the ignition and combustion of the low-rank coal. When the coal with high volatile content was mixed with the biomass, the co-combustion characteristics were the almost same as the coal combustion characteristics. NO and N2O behaviors under the co-combustion condition were similar with those under the coal combustion condition even though the input of fuel nitrogen became half under the co-combustion condition. Its tendency also depended on the coal type. This is may be caused by the difference of volatile nitrogen species evolved during the combustion. P4-3

Verification of Most Brown Coal Briquetting

Vera Sedlackova, Bohumil Straka, MUS,A.S.Most, Peter Fecko, Mining

University Ostrava, CZECH REPUBLIC

The aim of the work was to verify utilization of naturally originated fine-grained fraction that becomes during some time unseleable. It relates to final types of Most brown coal: HRUBOPRACH 1, and coarser OŘECH 2. Other reason was verification of the production of this new products according to valid legislative laws. Character of the Most brown coal with minimum content of bituminous constituent (as essential coal property for briquetting without binder) predestinated choise of binder technology.

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Low-ash high-calorific types of coal mined at Československá Armáda Mine exhibit from 1.2 to 2.0% from original sulphur content. (Sr). The sulphur dioxide emission amount in flue gas 3500-500mg.m-3 by combustion of this fuel on non-ecological consumer. Selective coal mining with lower sulphur content is unacceptable because of large-size machine mining technique. One solution how to reduce gas emission of SO2 was selection of suitable additives during briquette production. These parameters of briquette mixtures were tested in the work: • Grain size composition of charge coal • Type and amount of binder • Water content in mixture • Temperatute interval of briquette mixtures • Additives of briquette mixtures The goal of experiments and laboratory testing verified on pilot plant of MUS, a.s –ÚUK was to define and determine of optimize composition nad condition for preparation of briquette mixtures, that are intended for brown coal binder additive briquette production (at low pressing presure 25-30 MPa). P4-4

Greenhouse and Environmental Management of Coal Life Cycle

Michelle F. Li, Branislav Grbovic, Alan Carmody, Alberfield Group of

Consultants, AUSTRALIA

Since the advent of the Industrial Age, coal, oil, and natural gas have fuelled the world’s economic growth. The burning of fossil fuels in human activities at an increasing rate over the past century has resulted in similar rises in emissions of carbon dioxide (CO2), the most prevalent of the greenhouse gases that naturally regulate the earth's temperature. It is widely held that the increase in CO2 emissions from human activities is contributing to the perceived global warming trend. This paper reviews current and proposed developments in greenhouse gas emissions and related environmental waste reduction options pertinent to each stage in the coal life cycle from source, such as capture of methane during mining, through coal preparation and storage and on to reduction of process and stack emissions. The paper examines and assesses the relative economic and environmental merits of the strategic approaches of "Clean Technology" versus "Clean-up-Technology" including a review of current and proposed technologies in these areas such as the Borovac coal cleaning process, coal gasification and co-firing with renewable and other waste materials. The paper concludes with a brief look at current carbon fixing options for the coal industry taking CO2 directly from the atmosphere and the use of carbon credits to offset emissions generated throughout the coal life cycle. The options open to coal miners and coal users in this area are assessed in terms of the potential costs and benefits to their overall operations and presented with some novel proposals to take advantage of this largely unexplored area. The following areas are examined in detail: Dealing with Methane - Uses explored range from direct piping and sale to nearby metropolitan areas to in situ storage and utilisation for power generation by the mine and local supporting infrastructure. Mine Waste - To help restore and reclaim abandoned coal lands, reduce acid mine drainage (AMD) and greenhouse gas emissions, a number of technologies are examined. The concept of paste backfilling using CCBs and coarse coal refuse, (gob) is one that has the potential to enhance mine economics through higher recovery and reduced environmental impacts such as mine subsidence. Coal Preparation - The importance of burning a prepared coal at a low cost has been at the centre of the industry's attention for many years. The following areas are considered; Development and deployment of innovative methods, technologies, and materials to improve efficiency; Deployment of a cost-effective, "clean-coal". Coal Combustion/Gasification - A review of current and proposed coal gasification technologies and their proper application in terms of economics and coal types is presented. Ecoprofit and Technology Transfer - The benefits to coal miners and coal users in this area are assessed in terms of the potential economic and environmental costs and benefits to their overall operations as against restricting technology transfer on current strictly economic grounds. P4-5

Mechanochemical Activation of Brown Coals: Effect on the Structure and

Hydrogenation Reactivity

Peter N. Kuznetsov, Ludmila I.Kuznetsova, Alexander N.Borisevich, Institute of Chemistry and Chemical Technology, RUSSIA, Burtron H. Davis, University of

Kentucky, CAER, USA

The major part of coal represents a self-assembled supramolecular network in which aromatic, hydroaromatic and heteroaromatic structural units are cross-linked by short covalent bonds and by different kind of non-covalent interactions as well. Hence, any use of coal as a chemical feedstock requires extensive depolymerization of its macromolecular matter. Much attention has been paid to the effect of mild depolymerizing pretreatments of coals to improve their reactivity for subsequent thermochemical conversion processes. Different chemical, physical and also mechanical pretreatments were applied to improve the reactivity for the hydrogenation, solubilization and pyrolysis reactions. Mechanochemical activation is considered to be a promising procedure because it requires no costly reagents. However, the data regarding the nature of the phenomena affecting coal behavior are still not completely understood. The objective of this paper was to study the effect of mechanochemical treatment of brown coals of different composition on the characteristics of supramolecular organization and the reactivity for thermochemical conversion into the low molecular products under the hydrogenation reaction with tetralin solvent. Mechanical activation was performed in a centrifugal planetary ball mill with two drums cooled with water while operating. Mechanically-induced rearrangements in the supramolecular structure of coal were studied by ethanol and tetrahydrofuran swelling measurements and by extraction with ethanol-benzene mixture. X-ray diffraction was used to characterize the ordered portion of coal. The hydrogenation reactivity of mechanically pretreated coals was tested in the reaction of hydrogenation with 12 MPa of hydrogen in the medium of tetralin solvent at 3800C. The mechanical treatment was shown to induce significant changes within the macromolecular matter of the parent brown coals. As the mechanical loading increased, physical structure became more disordered and flexible that were manifested by the enhanced extract yield, THF swelling rate and swelling ratio, by less developed X-ray diffraction patterns, and also by improved thermochemical conversion into the low molecular products. Contrary to this, little or no effects were indicated when the demineralized brown coal was subjected to the mechanical activation during 5-15 min. The data have demonstrated mechanochemical pretreatment to be the effective method to improve the reactivity of brown coals for the hydrogenation. The mechanism by which reactivity is increased by mechanical pretreatment relates to the depolymerized and flexible supramolecular structure, caused mainly by the disruption of strong ionic metal carboxylate cross-links.

POSTER SESSION 5 METALLURGICAL AND NON-FUEL USES OF COAL

P5-1

Pyrolysis of Coal and Additives as a Source of Lustrous Carbon in the

Foundry Mould

Jaroslav Buchtele, Václav Roubícek, Petr Jelínek, Jaroslav Fiala, VSB - Technical University of Ostrava, CZECH REPUBLIC

The surface quality of castings is a crucial criterion for their commercial applications. What decides the surface quality is the content of lustrous carbon formed by the pyrolysis of coal and carbonaceous additives at the interaction of grey cast and spheroidal graphite cast iron and the foundry mould. The process of pyrolysis was modelled on the laboratory pattern, where the separation of the following forms of pyrolyzed carbon occurred: lustrous carbon, amorphous carbon and so-called “fly” carbon. It was the highest density, the lowest oxyreactivity (TA) and the highest structural arrangement (Hat/Cat ratio, X-ray diffraction) that was characteristic of lustrous carbon. Lustrous carbon is formed by heterogeneous nucleation in the process of pyrolysis on the inactive surface of quartz grains of the foundry mould. The mould thus becomes metal-phobic and guarantees the required high smoothness of the casting. P5-2

Numerical Analysis of Coke Carbonization Behavior in Coke Dry

Quencher: Effect of Air Introduction at Pre-chamber on Coke Quality

Aoki Hideyuki, Matsushita Yohsuke, Yagi Tetsuya, Yayamamoto Tsuyoshi, Miura Takatoshi, Tohoku University, JAPAN

A coke carbonization behavior in Coke Dry Quencher (CDQ) was numerically analyzed in order to understand the effect of air introduction at pre-chamber in CDQ on coke quality. A partial combustion of partially carbonized coke in CDQ is proposed in SCOPE-21 (Super Coke Oven for Productivity and Environment enhancement toward the 21st century) national project in Japan. In this project, since the coking temperature in oven chamber is less than 973 or 1073 K, coke strength is not enough for use in the blast furnace. In order to

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improve the coke strength, it is proposed in SCOPE-21 that pre-chamber in CDQ is used as a re-heating reactor of coke by introducing air. It is necessary to understand the way to improve the coke strength effectively. We developed the numerical model for CDQ. Gas flow is described by Navier-Stokes equation and a momentum exchange between gas and moving bed of coke is considered. A solid phase is assumed to be a Newtonian fluid. Gas and solid phase temperature are calculated with considering heat exchange. Further coke devolatilization reaction is calculated by a parallel first order chemical reaction model. Gas phase and solid surface chemical reactions are also considered. Governing equations above-mentioned are simultaneously solved by control volume method. In the calculation condition, void fraction of coke moving bed is 0.55, coke feed rate is 190 t/hr, coke initial temperature is 1073 K, air flow rate is 150 Nm^3/t-coke and quenching gas flow rate is 1400 Nm^3/t-coke. The effect of air introduction from pre-chamber and the effect of released volatiles from coke on gas and solid temperatures were discussed. Numerical result shows that air introduction causes gas and solid phase temperature rise and coke is kept at 1400 K over an hour. This may result in improvement of coke strength. Volatile matter combustion released by re-heating also plays an important role in temperature rise in the pre-chamber. However radial temperature deviation was observed in CDQ pre-chamber. This is caused by an endothermic reaction of gas species and coke and the gas flow deviation in the moving bed of coke. It may be necessary to control the radial distribution of coke diameter in practical CDQ operation. P5-3

On Characterization of Ignition and Burning Out Behavior of Coke for Use

in Lime Kiln

Steffen Krzack, Bernd Meyer, Freiberg University of Mining and Technology, GERMANY

A usual way of calcination of limestone is the shaft kiln process, in which large grained coke is used as a fuel. The aim is the nearly complete conversion of limestone into reactive quick lime. For that, the uniform continuous heat transfer over the shaft kiln height is a basic requirement. It means that the coke has to burn out uniformly continuous without the creation of temperature peaks. Beside the process conditions, the ignition behaviour and reactivity of the coke must be taken into consideration. There are different methods for determination of ignition temperature and reactivity of grained coke. The most common standard methods use a quantity for the valuation of coke (mostly the CO concentration during the coke gasification under quasi-isothermal conditions). For the characterisation of the burning out behaviour of the coke in a lime kiln, the examination of the whole burning out process is better suited. The thermal analysis was chosen for that. In this process, a fixed bed of grained coke in a wire basket is coupled with a thermal balance and linear heated under CO2/air-atmosphere. In addition, a test method with a linear heated fixed bed reactor under air flow was used for the determination of the ignition temperature of the coke. The good reproducibility is the feature of both test methods. Different samples were investigated and compared: dry and wet quenched hard coal cokes from different regions, a high-temperature brown coal coke, a petrol coke and an anthracite. The courses of burning out were described by the ignition temperature (between 350 and 550 °C), the maximal conversion rate (2,9 to 4,3 %/min referring to start weight), the temperature of maximal conversion rate (560 to 760 °C) and the period of conversion (35 to 45 min). Even if the data depend on the test conditions, conclusions could be drawn for the expected behaviour of the different fuels in technical scale. This was also confirmed by the use of some cokes in a large-scale lime kiln. P5-4

Production and Use of Fuel Suspensions from Tar Wastes

Thomas Kuchling, Petra Kuchling, Freiberg University of Mining and

Technology, Berthold Gartner, Institute of Energy and Environment Leipzig, GERMANY

In Germany, brown coal was used as a fuel in power plants or home firing plants in large amounts. Besides this use, its thermal upgrading by gasification and carbonization plays a very important role over more than 80 years, especially in East Germany. Tars and oils, produced as by-product in such processes, have often no suitable use. Problematical tar products, like thick tar spoiled by dust and water, were frequently disposed without control. On the area of the former G.D.R., there are still three very large tar deposits, called tar lakes, which contain more than 600.000 tons of tar waste products. These tar lakes are extremely dangerous for

environment, as often no protection against emissions of light components (BTEX aromatics) and ground water pollution by hydrocarbons is available. These deposits are on the one hand characterized by high and strong fluctuating contents of solids and water in the range from 1 to 50 wt % and on the other hand by high calorific values (higher than 25 MJ/kg). Known thermal processes of coal upgrading like combustion, gasification and pyrolysis are suitable for the disposal of tar lake products. However, a preparation of the waste material is necessary before the thermal treatment. This paper reports the production of homogenous and stable fuel suspensions from such tar waste products by mixing some additives (water, oil). They are responsible for stabilizing the mixture and reducing its viscosity. A particular intensive mixture requires a special mixing apparatus. In the present case, the so called cavitation generator was used. Furthermore, the combustion experiments in a 100 kW combustion chamber will be introduced. For those, fuel suspensions with different compositions were burnt. Results show, that a stable combustion (ignition, burn off) is possible under all conditions, even at extreme high water contents in fuel (> 60 wt %). By a gradual optimization of the spraying conditions and the air addition, it is possible to keep the limits of NOx and CO in flue gas. Thereafter, a technical solution for production and combustion of fuel suspensions will be presented and economically assessed. P5-5

Investigation of Exfoliated Anthracite to Produce Nanoscale Carbon

Material

Erin K. Boland, John M. Andrésen, Caroline E. Burgess, Harold H. Schobert, The Pennsylvania State University, USA

Nanoscaled carbon materials, such as nanotubes, have received tremendous scientific attention due to their great potential uses. However, the development of nanoscaled materials is marred by high costs, which may inhibit their widespread use. Accordingly, the present study investigates exfoliated anthracite as a candidate for producing nanoscaled carbon materials. The exfoliated anthracite could be a precursor to final products that may have many industrial uses. These products may include graphite, activated carbons, separation materials or storage mediums for gases and molecular sieves. Anthracites that would lend themselves to the creation of well-exfoliated products were chosen based on their physical properties. Two pre-treatments, one using perchloric acid and the other using a mixture of perchloric and nitric acids, were used to intercalate the anthracite. A thermal shock on the order of 600°C was used to exfoliate the anthracites. Further, the exfoliated anthracites will be analyzed to determine the extent of the physical changes that have occurred. Analysis will include using microscopic and surface area techniques. These physical changes will be related to the performance of the exfoliated anthracites for purposes such as gas storage. P5-6

The Nature of Plasticity Phenomena of Coal

Masakatsu Nomura, Koh Kidena, Masataka Hiro, Mika Katsuyama, Satoru

Murata, Osaka University, Tsukasa Chikada, Sumitomo Metal Industry Company Ltd., JAPAN

The nature of the coal plasticity was discussed by referring to the results concerning chemical structure obtained by 13C-NMR spectra and Ruthenium ion catalyzed oxidation reaction. Three coals, Witbank coal, Goonyella coal and J-East coal were employed, the first one being a very weak coking coal, the second strongly coking coal and the last non-coking coal. The solid 13C NMR spectra can give an average ring size of coals, the size of first one and second one being 2-3 rings while the last one showing 4-5 ring size. Ruthenium ion catalyzed oxidation reaction can give valuable information about alkyl pendant groups on aromatic rings and bridge bonds connecting two aromatic clusters. Right now this oxidation reaction shows the slight difference about bridge bonds and pendant alkyl groups between Witbank coal and Goonyella coal. Heating three coals near the softening temperatures yields gas and tar along with char. These char were submitted to solvent extraction where the char from the first coal gave a lot of tar and the second one showed slight amount of tar. However, the third coal gave a tar on heating up to more than 450oC, so this indicating that this coal shows no plasticity. The oxidation reaction of this coal is expected to give very valuable information about bridge bonds and we are now carrying out this reaction. Probably the bridge bond distribution may be quite different from other two coals. At present time Witbank coal spends so much hydrogen to afford tar and gas and when the char reaches the softening temperature there are slight amount of transferable hydrogen. Therefore the plasticity needs the presence of high molecular weight tar and char can depolymerize gradually to use transferable hydrogen to stabilize the fragments from char. Goonyella coal

62

can do this while Witbank coal can not do that due to the lack of transferable hydrogen. These phenomena can be seen with the experimental of rapid heating of char and coal. The distribution of solvent soluble fraction from char at the softening point, max fluidity temperature and resolidification temperature showed similar tendency. Finally the nature of coal plasticity can be rationalized by referring to the chemistry of coal at the softening temperature, max fluidity temperature and resolidification temperature. P5-7

Study on Synergism of Coal-Based Acid on the Biological Activity of

Glyphosate, an Herbicide

Zhang Caifeng, Li Shanxiang, Li Baoqing, State key Laboratory of Coal Conversion, Li Wen, Na Wang, Chinese Academy of Sciences, Zhang Qi,

Shanxi Academy of Agricultural Science, P. R. CHINA

A water-soluble coal-based acids (W-WSCA) were prepared by twice HNO3 oxidation with catalyst from a low rank Wuchuan coal not containing fulvic acid. In addition, a water-soluble fulvic acid J-WSCA was extracted directly from a low rank Jincheng coal containing original fulvic acid. The effect of both W-WSCA and J-WSCA on the biological activity of glyphosate a herbicides, was investigated. The results showed that W-WSCA and J-WSCA enhanced the biological activity of glyphosate about 1.51 and 1.47 times in ED50 level respectively, while 2.33 and 2.24 times in ED90 level respectively. Synergistic coefficient increased with the intensification of the bonding between glyphosate and water-soluble coal-based acids. The synergism was verified by the field tests of glyphosate against weed in orchard. The synergism was different with weeds and about 8 folds remarkable effect was observed against Lafopsis syouba. P5-8

Synthesis and Properties of a Novel Polyarylate with 9,10-

Dihydrophenanthrene-2,7-Dicarbonylate Moiety

Y.Kubota, A.Takeno, M. Miwa, Gifu University, Y. Ishigure, Gifu Prefectural Government, T. Yamauchi, K.K. Nissei Kagaku Kogyosho, M. Niikawa, Tenryu

Industries Co. Ltd., JAPAN

A novel polyarylate synthesized by carbonylation-polycondensation with 2,7-dibromo-9,10-dihydrophenanthrene and 2,2-bis(p-ydroxyphenyl)propane is expected to be one of the candidates for matrix of recyclable FRP because of its high solubility in many solvents. In this study, thermal, solution and mechanical properties of the polyarylate resin were discussed to establish the processing method or to design new FRP. The results were as followings. (1) Thermal property: initial degradation temperatures of this resin were 332-420 deg. C in the air atmosphere and 420-483 deg. C under nitrogen gas flow. It had high heat stability. Activation energy of thermal degradation reaction in the air calculated by Ozawa method was 89 KJ/mol. (2) Solution property: intrinsic viscosity (eata)of this resin was 0.46 and their viscosities under the steady shear flow were 22, 250 and 7200 MPa.s at the concentration of 5,10 and 20g/dl in chloroform solutions respectively. (3) Mechanical property: the tensile strength and modulus were 44.5MPa and 1.23GPa. respectively, and they are roughly the same as those of conventional unsaturated polyester resin exhibited the dynamic viscoclastic behavior like typical amorphous polymer and the glass transition temperature of this polymer estimated by this measurement was about 270 deg. C.

POSTER SESSION 6

FLUIDIZED COAL COMBUSTION

P6-1

Processes in Large-Scale CFBC

T. Ochodek, F. Johnson, B. Leckner, E-U. Hartge, J. Werther, W. Nowak, R. Sekret, P. Noskievic, VSB-Technical University Ostrava, CZECH REPUBLIC

Four European universities and three industrial partners are involved in the project “CFB Combustors”: Chalmers University of Technology, Technical University Hamburg-Harburg, Technical University of Czenstochowa, Technical University of Ostrava, Vattenfall Generation Services AB, Foster Wheeler Energia Oy and Power Plant Turow. The purpose of this project is to increase the understanding of the processes in large-scale CFB combustors and to validate extrapolation models. There is a need to confirm available speculation and modelling related to the performance of a large-scale CFBC during both steady state operation and during transients in connection to load changes. New information will lead to a possibility to interpret and understand

the operation of large-scale boilers, their combustion and environmental performance. The project is divided into seven main tasks: • Analysis of measurement • Hydrodynamic measurement • Combustion and emission measurement • Dynamic behaviour • Analysis of results and discussion The proposed measurements are planned to be carried out in one of the largest CFB boiler in Europe. Measurement campaign will come true on May 2001 and actual experience and the first knowledge will be presented in the paper. P6-2

Roles of Coal Ash in the Fluidization Behaviors of Bed Material in PFBC

Boiler

K. Iwamoto, F. Ishom, Y. Korai, I. Mochida, Kyushu University, T. Harada, Nishinippon Environmental Energy CO., LTD, T. Aoyagi, Kyushu Electric

Power CO., LTD, JAPAN

PFBC has been commercialized for a time, however some coal combustion was found to suffer poor fluidization, resulting in sincere slugging problem at the bottom of boiler when full load coal charge was operated. The bed material before the slugging problem at full load operation was found to carry three types aggregates of ash and bed material. The aggregates were analyzed in terms of their morphology, compositions, and properties to estimate the mechanism of their formation. Minerals and ash of two coals, which suffered poor fluidization and is expected to be smoothey combusted under similar composition, respectively, were analyzed by SEM, EDAX. Two coals carried different minerals in their fine ash region, although large ashes were such the same. Some of fine fly ash minerals appear to prohibit the formation of aggregates, which favors the smooth fluidization by the gas-flow as designed. P6-3

Mathematical Modelling of Fluidised-Bed Gasifiers

Hong-ming Yan, Dong-ke Zhang, Curtin University of Technology,

AUSTRALIA

A mathematical model, incorporating the two-phase theory of fluidisation, has been used to simulate performance of fluidised-bed coal gasifiers of various scales. The model can generate a set of information that is necessary for evaluating gasifier performance, improving operation of existing plants and designing of new gasifiers. Simulations show that the predicted overall carbon conversion, operating bed temperature and concentrations of individual gas species compare well with experimental data from four pilot-scales and a full scale fluidised bed coal gasifiers published in the literature. In-bed axial gas concentration profiles for O2, CO, CO2, CH4, and C3H8 were also compared well with the experimental data from a laboratory-scale gasifier at operating bed temperatures of 850oC and 950oC, respectively. The model simulations have identified that the predicted axial temperature profile of gas phase experiences a rapid heat-up period in the lower part of the bed that matches the real situation occurred in the gasifiers. The fastest reaction rates of the gas combustion occurred near the distributor show that the importance of considering the competition of oxygen between carbon combustion and gas combustion in gasifier modelling, particularly for coals with high volatile contents. The more the combustible gas available, the less the oxygen consumed in the char combustion because of the competition. In addition, the higher the operating temperature, the more and the faster the oxygen consumed in the gas combustion, because of the gas combustion is temperature dependent but the char combustion is mass-transfer dependent.

POSTER SESSION 7 PYROLYSIS AND DIRECT COAL CONVERSION

P7-1

Model Prediction of Thermal-Plastic Property of Australian Coals at High

Heating Rates and Elevated Pressures

Jiang-long Yu, John A Lucas, Gui-Su Liu, Vladimir V Strezov, Terry F Wall, University of Newcastle, AUSTRALIA

63

Coal particles undergo complex physical changes during devolatilisation, resulting in residual chars with sophisticated structures that have been found to play significant roles in burnout and ash formation during combustion and gasification. Fundamental understandings of char formation during heating at high heating rates and pressures have not been well understood. In the current work, a mechanistic model has been presented for simulating coal particle swelling behaviours and char structure evolution based on bubble mechanism. In particular, the thermal plastic property, for instance, viscosity has been carefully examined by existing devolatilisation models, which, to a large extent, determines the formation of char structure. CPD model has been used to predict the viscosity of an Australian coal at heating rates of 102-104K/s, and over a pressure range of 1 to 50 atm. As a comparison, results predicted from FG-DVC model were also presented. Upon heating, the viscosity of coal melt basically decreases to a minimum value with increasing temperature, and increases thereafter. Softening point, i.e. the onset of plastic stage of coal particles, is determined by setting a critical viscosity value. Plastic stage occurs at higher temperature when coals were heated at higher heating rates. High heating rates also result in larger temperature interval for plastic stage. At higher ambient pressure, more metaplast exists in coal matrix and results in a slight decrease in viscosity. In the meantime, pressure shows much less impacts on viscosity compared to heating rates. The predicted viscosity at different heating rates and pressures have been used in the char structural formation model which is being developed for simulating coal particle swelling behaviours. P7-2

Effect of Gaseous Additive on Desulfurization

of Coal Pyrolysis

Long Xu, Yunmei Li, Jianli Yang, Zhenyu Liu, Chinese Academy of Sciences, P. R. CHINA

It has a great need for the development of clean coal technology, especially for sulfur removal. Detailed understanding on the sulfur evolution during conversion process is essential. In this paper four Chinese coals (Yanzhou, Datong, Pingshuo and Shenhua) were studied for sulfur evolution during processing. A novel on-line analysis method was introduced. The method can monitor the sulfur released from coal quantitatively and continuously during processing. The apparatus setup includes a controlled atmosphere temperature-programmed decomposition part (CA-TPD) and a flame photometric detector (FPD). Four coals with different sulfur distributions were decomposed with a slow heating rate (5oC/min) to 800oC under desired atmospheres. The effects of atmosphere (N2, H2, N2+H2O, N2+CH3OH) on sulfur removal during pyrolysis were investigated. A higher desulfurization was observed for the case of that N2+CH3OH atmosphere was introduced. A free radical mechanism was proposed. P7-3

Transformation of Na, K, Pb and Mn during Coal Pyrolysis

Ruixia Guo, Jianli Yang, Dongyan Liu, Zhenyu Liu, Chinese Academy of

Sciences, P. R. CHINA

Although the content of sodium and potassium generally account for less than 1% of the raw coal, their present causes severe fouling and corrosion of the turbine blades during power generation process. Sodium and potassium released from coal as vapor or fine particles during coal combustion. The detailed understanding on the chemical and thermal stability of sodium and potassium during coal processing is desirable in guiding for effort on their effective control. In this paper is reported the transformation of sodium and potassium in Shenhua coal during pyrolysis process. The pyrolysis experiment was carried out in a simulate-drop-tube apparatus with a heating rate of 1000 Ks-1. The experiment temperature ranges from 300oC to 800oC and pressure from atmosphere to 5MPa. The transformation behavior under N2, H2 and CO2 were studied. The effects of pyrolysis temperature, pressure, and holding time were also included. The pyrolysis temperature was found to be the most influential factor for Na and K evolution. P7-4

A Study on Sulfur and Boiling Point Distribution of Oils Derived from

Coprocessing of Coal and Petroleum Resid

Wensheng Linghu, Zhijie Wang, Yongbing Xue, Jianli Yang, Zhenyu Liu, Chinese Academy of Sciences, P. R. CHINA

The systematical recognition of the properties of coal derived oils is important for its upgrading and the process improvement. Both sulfur and boiling point distribution of oils produced by coprocessing of coal and petroleum resid were studied in this paper. The coal used was Yanzhou coal, a Chinese bituminous coal. The resid used was catalytic cracking bottom, from Shijiazhuang oil refinery of China. The derived oils were analyzed simultaneously by flame photormetric and flame ionization detectors coupled with a gas chromatography. The results show that the content of middle distillates goes through a maximum with increasing temperature at the range of 375~4500C. Compared with nitrogen atmosphere, hydrogen atmosphere results more middle distillates. Reaction pressure and the catalyst used have little effect on the boiling point distribution. The results also show that the distribution of sulfur of derived oils depends mainly on the type of coal used, the propeties of resids and the reaction temperature.

POSTER SESSION 8

COAL PRODUCTION & PREPARATION

P8-1

Altair Centrifugal Jig: An In-Plant Evaluation for Fine Coal Cleaning

M. K. Mohanty, A. Patwardhan, Southern Illinois University at Carbondale, R. Q. Honaker, University of Kentucky, USA

Coal preparation plants treat a majority of the run-of-mine coal using various gravity processes, which are known for their low cost and high process efficiency values. Due to the inefficiencies of the conventional gravity-based processes at treating fine coal particles, at times below 28 mesh (600 micron) particle size, more expensive froth flotation processes are traditionally used to treat this fine coal fraction. Several enhanced gravity separation technologies have been developed during the last two decades to expand the lower particle size limit of efficient gravity separation up to nearly 325 mesh (45 micron). Altair Centrifugal Jig is one such enhanced gravity technology, whose suitability for fine coal cleaning has been demonstrated through an in-plant study conducted in this investigation. A relatively low specific gravity cut-point of 1.49 with a probable error value of 0.10 over a wide particle size range of 1mm x 45 micron is indicative of the excellent separation performance achievable from the Altair Jig. For the experiments conducted without the use of ragging materials to enhance the throughput capacity of the Jig and to simplify the Jig operation with an autogenous ragging bed of coarse coal particles, significantly low mass yield and combustible recovery values were obtained. It is believed that the relatively low solid content of the plant fine coal feed of nearly 8% was able to provide only a thin autogenous ragging bed on the jig screen. Pulse water pressure, even at its lowest level of 3 psi, was able to excessively fluidize the bed and thus, caused the loss of a significant amount of clean coal particles to the tailings stream through the jig screen. P8-2

Contribution of Mechanic Activation of Coal to the Develpoment of Theory

and Practical Aspects of Advanced Coal Technologies

L. Turcániová, P. Baláz, The Institute of Geotechnics of the Slovak Academy of Sciences in Košice, SLOVAKIA, Robert La Count, Virolac Industries, USA, Mária Bežovská, Mária Mulová, Technical University of Ostrava, CZECH

REPUBLIC The paper presents the explantation of the effect of activation grinding in attrition mill in order to achieve favourable environmental and technological results. The effect of mill revolutions, grinding time, shot and concentration of leaching agent was studied in laboratory conditions during the mechanochemical grinding of brown coal from Nováky. In addition to surface-structural characteristics, the activation effect of grinding has been also evaluated on the basis of changes in the organic structure (CHO) of coal using CAPTO method. In order to improve the filtration parameters of fine-dispersed brown coal, the effect of concentration of alkaline agent was studied within the range of 5 – 0,1% weight. It was confirmed that favorauble environmental (detoxification, desulphurization, reduction of contents of ash matters, etc.) and treatment (increase in the extraction of treated coal) effects were achieved under conditions of stable structure of humic acids. The target regulation of mechanochemical changes represents a potential possibility of this progressive mechanochemical method for the preparation of rare organic diterpene-based substances. These substances can be used as pharmaceutical effectors in production of medicaments. In relation to information published by the scientific mechanochemical school of Russian scientists, it is possible to expect that this mechanochemical procedure will have a more complex use in environmental areas.

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P8-3

The Relationship Between Coal Flotation Froth Characteristics and Feature Measures

Wenli Liu, Fang Wan, Yong Wang, Maixi Lu, CUMT, P. R. CHINA

In this study, an experimental flotation column is designed and made, and also an experimental system is set up for acquiring froth image. By conducting a lot of batch cell flotation experiments, a series of froth images are acquired. Based on the analysis of the flotation froth visual characteristics and its relationship with the procedure variables, two kinds of effective algorithms are presented. And a series of feature measures are extracted from coal flotation images. The change tendency of each feature measure with the flotation time is analyzed, and the relationship between each feature measure and froth textural feature is pointed out qualitatively. P8-4

Dry Classification and Separation of 6~0mm Coal

Fan Maoming, Chen Qingru, Zhao Yuemin, Luo Zhenfu, Zhang Xinxi, Yang

Guohua, China University of Mining and Technology, P. R. CHINA

The quantities of coal being separated and the levels of separation required are increasing while the quality of raw coals is decreasing. Although coal is currently cleaned with the minimum of size reduction, fine particle processing, recovery, and tailings disposal are major problems. Furthermore, adequate water resources are not always available. For example, two thirds of China’s coal are located in arid areas. Hence, dry separation provides an alternative approach. Of the dry separation methods available, air dense-medium fluidized beds have been used to separate 50~6mm coal efficiently. In this study, the authors studied magnetically stabilized fluidized beds and vibrated fluidized beds for separating fine coal, triboelecttric beneficiation of ultrafine fine coal and the fine coal dry classification method. This paper discusses the principle of the above fine coal separation and classification methods, the experimental system, and the test results. Program supported by the National Science Fund for Distinguished Young Scholars (No.50025411) and the National Natural Science Foundation of China (No.59974030). P8-5

Research on the Deashing Agent During Selective Oil Agglomeration

YangQiaowen, Liu Liping, Shi Xiankui, China University of Mining &

Technology, P. R. CHINA

Pingdingshan tailing was chosen to be the feed coal whose ash content is 25%. The analysis of coal nature, FT infrared spectrogram and lithofacies were determinated. Eight deashing agents were tested in beneficiation by selective oil agglomeration. It included dispersant and agglomerant of mineral matters of coal whose function was very different. Several composite agents were prepared and tested and the effect of TH80 agent was obvious. The ash content of beneficiated coal was reduced to 12% after one time beneficiation. The Zeta potential interface of coal and water were determinated whose value were different when the different deashing agents were added. The Zeta potential of coal was minus and decreased when the amount of dispersant was increased. The Zeta potential of coal was plus and decreased when adding more agglomersant.

POSTER SESSION 9

COAL COMBUSTION BYPRODUCTS UTILIZATION

P9-1

Efficacy of Utilizing Bottom Ash and Composted Manure as a Beneficial Soil Amendment Material

S. Mukhtar, J. G. Mathis, A. L Kenimer, Texas A&M University, USA

In the United States, nearly 100 million tons of ash products are produced including bottom ash, an incombustible byproduct of burning coal to generate steam and electrical power. Typically, this ash is retained at the power plant sites, adding to the cost of managing wastes at the plants. Another residual product requiring significant management efforts and costs is manure from large animal feeding operations in the country. Repeated application of manure on small parcels of land can contribute to environmental problems such as impaired water quality due to nitrate (NO3) leaching into the groundwater and phosphorus

(P) runoff into surface water bodies. Any alternatives to land filling of BA, and exporting of animal manure from areas of heavily manured soils to areas with little or no manure applied soils, if economically and environmentally sound, will be looked upon favorably by industry, environmentalists, and regulators. Alternative uses of bottom ash (BA) and composted manure (CM) such as soil amendment for landscapes, stripped mine cover, or potting soil need to be explored. Before an alternative is adopted at a large scale, however, it must be evaluated for its effectiveness and environmental integrity. Previously, a study was conducted to evaluate the utilization of BA and composted dairy manure as a soil amendment material. Five blends of BA and CM (0:100%), (30:70%), (50:50%), (70:30%) and (100:0%) packed in acrylic columns, were subjected to a constant head water table management. Leaching of N, P, K, NO3-N, NH4-N, total and volatile solids, COD as well as trace metals from these blends was investigated. It was concluded that higher CM content in the blend resulted in significantly higher leachate concentrations of these constituents. Based on the findings, two column studies were conducted to evaluate three new blends of BA and CM namely; B1(95:5%), B2(90:10%), and B3(80:20%). The first study comprised of acidic BA, a rare batch and CM blends, while the second study consisted of alkaline BA, most common form and CM blends. Samples from standing water (top) and leachate (bottom) were collected at weekly intervals to evaluate the effects of different blend ratios and time on the chemical and physical properties. Results comparing chemical and physical characteristics of standing water table and leachate for these three new blends, as well as blends with acidic BA versus alkaline BA will be presented. A discussion on the future field studies for selected blends based upon these column studies and potential of these blends for use as soil amendment material will be presented. P9-2

Ozone Treatment of Unburned Carbon Surfaces in Fly Ash

Arun Mehta, Electric Power Research Institute, Robert Hurt, Xu Chen, Indrek

Kulaots, Yuming Gao, Eric Suuberg, Brown University, USA

Unburned carbon in fly ash is known to adsorb the chemical surfactants used in concrete mixtures, making them unavailable for the stabilization of the micro-void system that is desirable for freeze / thaw resistance. Contacting fly ash with dry ozone-containing gases at or near room temperature has previously been shown to dramatically reduce the undesired adsorptive behavior of unburned carbon residues without removing significant amounts of carbon mass. The present paper will discuss the kinetics and mechanism of this ozone/carbon reaction, the changes in oxide functionality and carbon surface properties, and the progress in the development, scale-up, and evaluation of a commercial-scale ash treatment processes based on this principle. The process offers special advantages for an important class of ash samples derived from low-rank coals with low carbon weight fraction but high carbon adsorptivity.P12-1 P9-3

Geotechnical Characterization of Dry Flue Gas Desulfurization By-Products

Tarunjit E. Butalia, William W. Wolfe, The Ohio State University, USA

Dry Flue Gas Desulfurization (FGD) by-products are being generated across the world in increasing amounts. The SO2 scrubbing process resulting in dry by-products, as compared to wet FGD by-product (scrubber sludge), has several advantages from a desirable by-product perspective. Dry FGD materials can be stored and used as and when necessary, and do not harden if protected from moisture. They offer cost effective transportation from the generating facility to the project site since the cost of hauling moisture (which can be up to 50% for wet FGD materials) is significantly reduced. Dry FGD materials have compacted dry densities that are much lower than typical soils and can be compacted over a large range of moisture contents. Most wet FGD materials have moisture contents much higher than the optimum moisture content, while dry FGD materials contain little or no moisture and water can be added at the project site to achieve optimum moisture content conditions for compaction. The objective of this paper is present an overview of the geotechnical engineering properties and potential uses of several different types of dry FGD materials that are currently being generated and proposed to be produced from scrubbing technologies under research and development. The dry by-products studied in this paper include scrubbing technologies involving Duct Injection (DI), Lime Injection Multistage Burners (LIMB), Fluidized Bed Combustion (FBC), and Spray Dryer (SD). A total of 10 types of dry FGD by-products were investigated over a period of 5 years. The FGD by-products were tested in the laboratory for grain size distribution, moisture-density relationship, modulus of elasticity and strength, permeability, consolidation, swell potential, and durability under freeze-thaw cycling. The SO2 scrubbing process and curing

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time for samples significantly affected the engineering properties of the FGD by-products generated. For all the samples investigated in the study, the optimum moisture contents ranged from 18% (FBC) to 68% (SD, LIMB), while the maximum dry densities varied from 0.7 gm/cm3 (SD, LIMB) – 1.9 gm/cm3 (FBC). The 28-day unconfined compressive strength ranged from very weak (30 psi for SD) to high strength (1530 psi for FBC). The permeability at 28 days of curing ranged from medium permeability (10-6 cm/sec for SD) to very low permeability (10-10 cm/sec for FBC). The swell potential of the samples were measured for up to three years duration. The FBC and SD samples exhibited very little swelling (0.8%), while the LIMB process samples swelled nearly 70%. On the basis of the engineering characteristics of the dry FGD by-products, recommendations are made for their use in geotechnical engineering applications such as large volume structural fills and highway embankments. P9-4

X-Ray Fluorescence Spectrometry, a Quantitative Tool for Fly Ash

Analysis

Charles Wilson, Leroy Jacobs, Jane Thomas, Wyoming Analytical Laboratories, Inc., USA

Wavelength dispersive X_ray fluorescence spectrometry (XRF) is a very useful analytical technique for elemental analysis of fly ash. X_rays generated from a target and directed onto a solid or liquid cause a quantum disturbance in the electron shells of the atoms. The re_fluoresced X_rays from the sample are diffracted by a crystal, much like a grating in optical emission spectroscopy. The X_rays, now qualified by wavelength, can be impinged upon detectors which will quantify the amount of re_fluoresced X_rays. Application of the ASTM D4326 XRF standard procedure for coal ash to fly ash analysis is now an accepted procedure through the ASTM C9 committee for quality control purposes. The use of an XRF spectrometer to speed up and enhance routine elemental analysis of fly ash by the use of specific analytical techniques will be discussed. P9-5

Full Utilization of Coal Combustion Products in Maryland

Paul Petzrick, Department of Natural Resources, USA

Maryland currently produces about 1.5 million tons of coal combustion products per year. Only one third of this production is being used in manufacturing, construction, highway, and mining applications. Maryland’s production of coal combustion products is expected to grow to 2 million tons per year over the next decade and include a favorable combination of fly ash and fluid bed combustion products. The Maryland Power Plant Research Program would prefer not to recommend any further licensing of disposal of coal combustion products. To achieve this end the Program is conducting a series of demonstration projects to evaluate replacing commonly use portland cement and concrete as the cementitious material in standard geotechnical engineering applications with carefully formulated mixtures of power plant combustion products. These applications will include soil cement, bulk filling, construction of cutoffs or seepage barriers, and grouting. Seepage barriers are expected to include diaphragm walls, slurry trenches, secant drilled shaft walls, and tremie seals. Grouting applications are expected to include intrusion grouting, compaction grouting, and jet grouting. The initial demonstration of bulk filling a small abandoned underground coal mine in 1996 has produced outstanding results in terms of reduced acid production, reduction of heavy metals in the mine effluent, and stability of the mixture of combustion products and mine water as a hydrated solid in an acid mine environment. The latter consideration continues to be monitored by extracting cores of the hydrated material each year for analysis recognizing that ettringite-forming materials were intentionally included in the grout formulation and the environment in which the grout has been placed and hydrated is outside of the reported pH range of stability of ettringite. No adverse environmental impact has been identified related to this application of power plant combustion products. Based on these initial findings and extensive review of relevant literature additional demonstration projects have been planned or are being investigated. A project to construct a seepage barrier around an abandoned mine shaft through an eighteen foot aquifer at a depth of 40 feet has been co-funded by the Office of Surface Mining and is in the final stages of engineering design. Capping the high sulfur content pavement in a segment of the Kempton Mine Complex has also been co-funded by the Combustion Byproducts Recycling Consortium and is also undergoing final design. A succession of projects to reduce the loss of water from the North Branch of the Potomac River over the Kempton Mine Complex are being developed for implementation under a Cooperative Research and Development Agreement with the U.S. Department of Energy. The potential of completing a massive 2.5 million cubic yard structural fill at competitive cost using railroad

transportation of combustion products from four power plants over three years is under investigation. This project will involve soil cement stabilized shoulders and berms enclosing a structural fill of coal combustion products for a runway extension, as part of a funded airport expansion. Other projects being developed to demonstrate massive use of coal combustion products include: Larger seepage barriers related to mines, restoration of ground water flow around a Fayol type mine failure, trail surfacing, sinkhole restoration, deep in-situ mixing of coal combustion products and soil to make soil cement, and agricultural applications of coal combustion products as a slurry or in soil cement. This paper provides primarily a geotechnical engineering discussion of the completed project, projects underway and those being investigated for future implementation. Most of these demonstration projects are of a geoenvironmental nature and will require public funding for replication. The Maryland Power Plant Research Program intends to demonstrate that such projects can be completed at reduced costs using coal combustion products making more such projects feasible. P9-6

The Use of Power Plant Combustion Products in Maryland

Paul A. Petzrick, Maryland Power Plant Research Program, USA Maryland power plants produce about 1.5 million tons of combustion products per year. Currently about half of this production is put to constructive use in highway, mine, and construction applications. Five years ago the Maryland Power Plant Research Program initiated a series of demonstration projects to develop beneficial use of all of Maryland’s projected annual production of 2 million tons of combustion products per year. The focus of Maryland’s program is to demonstrate that a mixture of combustion products or combustion products and high lime content waste products can replace concrete as the cementitious material in most standard geotechnical applications and by improving the economics of such projects make more environmentally beneficial projects feasible. A demonstration of bulk filling a mine has been completed and is providing valuable data on the environmental performance of a mixture of fluid bed combustion products, fly ash, and flue gas desulfurization material used as cementitious material in an acid mine environment. Demonstration projects in seepage grouting, intrusion grouting, and covering a high sulfur mine pavement are underway. Maryland‘s 450 abandoned coal mines, numerous disposal areas, brown-field sites, and karst topographic belt are being studied to identify opportunities to demonstrate the use of combustion products in paste applications, tremie seals, diaphragm walls, secant drilled shaft walls, slurry trenches, solidification and stabilization of dredge fill, compaction grouting, jet grouting, in-situ deep mixing, and in impermeable caps and other soil cement applications.

POSTER SESSION 10 TRACE ELEMENTS IN COAL

P10-1

New Zealand Coal Resources and Coal Quality

Robert B. Finkelman, Jason C. Willett, USGS, Tim A. Moore, CRL Energy Ltd,

Zhongshen Li, University of Canterbury, USA

New Zealand coals are noted for their unusually low ash yields, commonly less than two weight percent. One consequence of these low ash yields is an unusual inorganic chemical composition. Data have been obtained on major, minor, and trace elements for 59 samples from eight New Zealand coal basins. Forty-nine of the samples are plies from 5 cores from the Brunner coal bed in the Buller coalfield, South Island. The average ash yield for these samples was 1.4 weight percent, with a minimum of 0.20 weight percent. For “major” elements in the 41 Brunner samples having 10 wt. percent ash or less, Si and Al contents in the coal are commonly less than 1,000 ppm and Ca contents were less than 400 ppm. Mg contents in the coal are commonly less than 10 ppm in 37 of these samples and in several samples Mg and Ni concentrations are similar. On an ash basis the chemistry of the New Zealand coals is even more unusual. One sample has more than 6,500 ppm Ni in the ash. Although As, in general, is low (less than 5 ppm in the coal) several samples had more than 1,000 ppm in the ash and two samples had more than 10,000 ppm. Despite the unusual chemistry, several elements (Si, Al, Ti, Li, P, Cu, V, Pb) have strong statistical correlation with ash indicating a detrital source. Other elements (Mg, Mn, Sr, Ba, Zn) correlate strongly with Ca, indicating a carbonate association. There are some apparent regional variations in coal chemistry. Coals from the North Island Waikato Coal Region have substantially higher B and Sr contents (both about 300 ppm) than do the South Island coals (generally less than 50 ppm for B and less than 30 ppm for Sr, except for the Southland Coal Region which has about 200 ppm B).

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Waikato and Southland coals have 17 to 42 weight percent CaO in the ash whereas coals from the West Coast Coal Region have about 1 weight percent. Despite pyritic sulfur values of 0.01-0.02 weight percent, coals from the Greymouth coalfield in the West Coast Coal Region have the highest Pb, Sb, Ge, and Tl values. P10-2

Trace Elements in Some UK Coals: Quantitative Distribution within the

Coal

D.A. Spears, University of Sheffield, UK Trace elements released from coal during utilisation are of environmental concern. Coals are therefore routinely analysed for a range of trace elements. In addition to concentration levels information is also required on the distribution of trace elements within the coal in order to understand the origin of the elements in the coal, thus enabling predictions to be made about other coals. Improved characterisation of the coal in terms of trace elements is also of value in utilisation, particularly in coal cleaning, but probably increasingly in other areas, as in combustion where it is recognised that the original location and association in the coal does influence the combustion behaviour. The different approaches that have been used to determine element distributions within coal will be reviewed. These include direct micro-analytical methods and a number of indirect methods, including the statistical analysis of trace element data. It is the latter approach, based on analyses of density and size-fractionated coal from the Yorkshire- Nottinghamshire Coalfield, that has been used to determine associations and distributions in the coal and from the regression equations to calculate the trace element composition of important fractions, which in these coals are organic matter, pyrite and the clay minerals. One check on the calculation procedures is to sum the contributions of the fractions and demonstrate that this corresponds with the whole coal analysis. This also emphasises that the trace element concentration in the coal depends on the abundance of the fractions and their compositions. The concentrations obtained for the different fractions are coalfield specific, although there are grounds for believing that they may have more general application.

POSTER SESSION 11 FLUE GAS CLEAN-UP & SCR/SNCR

P11-1

Simultaneous Removal of SOx and NOx Using Slaked Lime at Low

Temperature

Masanori Sakai, Caili Su, Eiji Sasaoka, Okayama University, JAPAN

SOx and Nox are the most commonly encountered air pollutants causing acid rain. These pollutants are emitted into the atmosphere mainly through industrial flue gases. The available commercial technologies for removal of SOx, such as, wet processes of Belco Tech. and Exxon, catalytic wet process of Haldor Topsoe, are multistep and costly. Moreover, NOx is removed by a process of selective catalytic reduction (SCR) with NH3. This process, as such, claims consumption of toxic and expensive ammonia. Therefore, it is desirable to develop a single-step dry process to remove SOx and NOx from industrial flue gases simultaneously. Calcium hydroxide based absorbents as one kind of the candidates for SO2 and NOx removal have been studied, but the efficiency of calcium utilization was low. Furthermore, the mechanism of the interaction of SOx and NOx with Ca(OH)2 has not been investigated in detail. In this paper, Slaked lime prepared from CaO particles swelled with water vapor at 80oC was used as sorbent, the CaO particles prepared by calcinations of the limestone (Chubu area of Japan) was composed of 55.43%CaO, 0.11%SiO2, 0.05%Al2O3, 0.001%P, 0.53%MgO, 0.015%Fe and 43.86% ignition loss. The reaction mechanism was studied using IR analysis. The experiments of the simultaneous removal of SO2 and NO were carried out using a flow-type packed-bed tubular reactor system under atmospheric pressure. The reaction temperature examined was mainly 90°C. In the experiments, a mixture of SO2(0 to 800ppm), NO(0 to 800ppm), O2(5%), CO2(10%), H2O(10%) and N2(balanced) was fed into the reactor at 200 cm3STP/min. Inlet and outlet concentration of SO2 and NO were measured using a non-dispersive IR and a chemical luminescence detector respectively. NO2 was converted to NO using KI solution and then measured using the chemical luminescence detector. The characterization of fresh and spent sorbents were carried out using mercury / N2 porosimeter, XRD, and FTIR. Activity examination results showed that SOx and NOx from coal combustion flue gas could be absorbed simultaneously by slaked lime at 90oC. During the first stage (from the start to 30min), SO2 and NOx could be efficiently removed by the slaked lime. The activity decreased with time due to the cover of sulfate

salts on the outside surface of the particles. The effects of the reaction temperature were studied in the range of 70-300oC, the removal of SO2 was favored at higher temperature, but 90oC is the most suitable temperature for the removal of NO. It is interesting that the reactivity of SO2 with the slaked lime was accelerated by the presence of NO. Moreover, NO did not reacted with Ca(OH)2 in the absence of SO2, and after injection of SO2, NO was gradually adsorbed and reached maximum value after ca.5min with evolving. FT-TR studies showed that SO2 was absorbed by Ca(OH)2 as SO3

2- in the absence of NO, While SO2 was absorbed as SO4

2- in the presence of NO. Thus, the oxidation of SO3

2- to SO42- was enhanced by NO. NO was absorbed as NO3

- and the presence of SO2 was indispensable to the NOx removal too. A reaction mechanism for the simultaneous removal of SO2 and NO was proposed based on the transition reaction data and FT-TR analysis. P11-2

Research on Roadside Atmospheric Scavenging Using Activated Carbon Fiber

Takaaki Shimohara, Hisao Chikara, Matayoshi Nakamura, Fukuoka Institute of Health and Environmental Sciences, Takashi Enjoji, Noriaki Shirahama, Isao

Mochida, Kyushu University, JAPAN In the vicinity of intersections with heavy traffic near densely built-up areas, polluted air likely stagnates, producing very high concentration of nitrogen oxides. For this reason, establishment of a scavenging technology against stagnant polluted air has become an urgent task, in combination with measures to counter local pollution, such as the improvement of road structure and the decrease of traffic volume. In such circumstances, the removal of nitrogen oxides in environmental air using highly activated carbon fiber (ACF), or environmental scavenging by the combination of conventionally used titanium oxide catalyst and ACF are attracting attention. Even though ACF has been developed for the purpose of adsorbing and decomposing sulfur dioxide and nitrogen oxides in factory waste gases, and basic researches on ACF have been conducted, few cases are reported on its application to common environmental air. This research has examined the application of 2 types of agents to environmental scavenging: OG20A-H1100 which was prepared by calcining OG20A, a pitch type carbon fiber, in an inactive gas at 1100•, and FE300-H800 which was prepared by calcining FE300, a PAN type ACF, at 800•. As a result, the following phenomena have been clarified. 1) The activity of FE300-H800 against the adsorption and decomposition of NO2 was a little higher than that of OG20A-H1100, and the activity of FE300-H800 against NO was remarkably higher in laboratory standard gases. 2) FE300-H800 received the effect of atmospheric moisture, and its activity against NO and NO2 remarkably decreased before the moisture adsorption reached saturation. However, by the removal of moisture, its activity was restored remarkably. On the other hand, in OG20A-H1100, this agent is sufficiently endurable to outdoor use. 3) Both OG20A-H1100 and FE300-H800 were proven to be effective against SO2 and NOx in actual environmental air. In addition, OG20A-H1100 was able to catch toluene, xylenes, trimethylbenzene and higher aliphatic hydrocarbons in addition to nitrogen oxides, even under high suction velocity of 1 liter/min. This study was granted by the Pollution-Related Health Damage Compensation and Prevention Association of Japan. P11-3

A Research into the Factors to Affect the Sulfur Fixing Characteristic of

Ca-Compounds

Xu Dongyao, Yang Qiaowen, Yu Yan, Wang Zuna, China University of Mining and Technology Beijing, P. R. CHINA

There are all kinds of factors which affect the sulfur fixing characteristic of Ca-compounds, such as sulfur fixing temperature and time, which had been researched carefully, on the basis of it, in this paper the effect of oxygen and moisture in combustion environment in a pulverized coal boiler on the sulfur fixing characteristic were studied. Oxygen and moisture are main environmental factors. It is found that increasing oxygen content and moisture in combustion environment will raise the sulfur fixing effectiveness of Ca-compounds. The effect of coal ash on the sulfur fixing characteristics of Ca-compounds also was studied. To change ash component and ash content can obtain a different sulfur fixing efficiency of Ca-compounds.

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P11-4

Effect of Mineral Matter on the Emission of NOx During Coal Combustion

Zongbin Zhao, Wen Li, Baoqing Li, Chinese Academy of Sciences, P. R. CHINA

The effect of mineral matter either inherently present in coal or deliberately added on the release of NOx during coal combustion was investigated. Four coals, ranging from lignite to anthracite, were demineralized with HCl and HF. The original coals and the corresponding deashed coals were combusted in a quartz fixed bed reactor under a programmed-temperature condition. Some Ca and Na-containing additives were also added to the deashed coals in order to elucidate the effect of individual defined component on the emission of NOx in coal combustion. The results showed that mineral matter could affect the release of NOx, which depended on the kind and amount of mineral matter in the coal. Na remarkably decreased the emission of NOx, while Ca enhanced the NOx emission level. In comparison with our previous work, it is found that mineral matter in coal played more important role in the char-N conversion rather than in the volatile-N conversion. In addition, the effect of mineral matter on the release of NOx was very complex during coal combustion, including many factors such as its individual component and combustion condition. It was also observed that the same component of mineral matter could both decrease and increase the emission of NOx at different combustion conditions, which implied the importance of catalytic condition. The mechanism of effect of mineral matter on the formation and destruction of NOx was discussed in details. P11-5

Improving IGCC Economics through ITM Oxygen Integration

VanEric E. Stein, Air Products and Chemicals, Inc., USA Edhi Juwono, Texaco Power and Gasification, USA

Elia P. Demetri, Concepts NREC, USA In partnership with the U.S. Department of Energy, an Air Products-led team is developing a new air separation technology - Ion Transport Membrane Oxygen - based on ceramic membranes that selectively transport oxygen ions when operated at high temperature. Under the influence of an oxygen partial-pressure driving force, the ITM Oxygen process achieves a high-purity, high-flux separation of oxygen from air. By integrating the energy-rich, vitiated, non-permeate stream with a gas turbine system, the overall process co-produces high-purity oxygen, power, and steam if desired. As a result, the technology is ideally suited for advanced power generation processes that require oxygen as a feedstock for combustion or gasification, making IGCC an ideal application for ITM Oxygen co-production technology. A subset of the ITM Oxygen development team, including Texaco Power and Gasification, Concepts NREC, and Air Products, recently completed a study of IGCC economics comparing the use of ITM Oxygen against a state-of-the-art cryogenic air separation unit (ASU). Both single-train IGCC designs featured a Texaco high-pressure quench gasifier operating on U.S. domestic coal, a raw syngas expander, conventional fuel gas cleaning and sulfur recovery, and a Siemens Westinghouse W501G gas turbine providing 100% air-integration, as well as 100% nitrogen/non-permeate-integration, for the oxygen plants. Compared to a highly-integrated cryogenic ASU utilizing an elevated-pressure, partially pumped LOX design, the ITM Oxygen plant is projected to decrease the installed capital cost of air separation equipment by 35%. Such savings decrease the installed capital cost of the IGCC facility by 7% from $1,094/kW to $1,020/kW. These results are consistent with ITM Oxygen integration studies performed on other advanced power system designs, and they underscore the expected economic benefits of ITM Oxygen technology. P11-6

Liquid Phase Methanol (LPMEOH™) Process Development

Edward C. Heydorn, Barry W. Diamond, Air Products and Chemicals, Inc., Ron D. Lilly, Eastman Chemical Company, Robert M. Kornosky, U. S. DOE/NETL

The Liquid Phase Methanol (LPMEOH) process uses a slurry bubble column reactor to convert coal-derived synthesis (syngas) gas to methanol. The LPMEOH™ process provides the means to convert synthesis gas to methanol at higher per-pass conversion than conventional gas-phase technologies. Because of its superior heat management, the process can directly utilize the carbon monoxide (CO)-rich syngas characteristic of the gasification of coal, petroleum coke, residual oil, wastes, or other hydrocarbon feedstocks. When added to a high-efficiency integrated gasification combined cycle (IGCC) power plant, the LPMEOH process converts a portion of the CO-rich syngas produced by the

gasifier to methanol, and the unconverted gas is used to fuel the gas turbine combined-cycle power plant. A 260-short tons per day (STPD) LPMEOH™ Process Demonstration Plant has been in operation at Eastman Chemical Company’s chemicals-from-coal complex in Kingsport, Tennessee since April of 1997 under a Cooperative Agreement with the U. S. Department of Energy (DOE). This demonstration project is part of the DOE’s Clean Coal Technology Program. Production rates of over 300 STPD of methanol have been achieved and the plant availability for the past three years has been 99%. This paper provides a description of the LPMEOH™ process and the application of the technology to IGCC power plants. Under a 15-month extension to the project, additional operating time will provide the opportunity to perform new tests of significant commercial interest (such as the activation of methanol synthesis catalyst in the LPMEOH™ Reactor). A review of the status of these tests and ongoing performance results will be presented.