Future Guidelines for Environmental Benefits

Presented by

C A CHOPKAR

THERMAL POWER PLANT- COAL BASED Super Critical Power Generation Units

This advanced technology for power generation

is for achieving

bull Higher Efficiency bull Clean bull Safe Overall Environmentbull The development of coal fired supercritical power plant technology can be described as an evolutionary advancement towards greater power output per unit and higher efficiency

CO2 emissions can be lowered by improving the efficiency of coal fired power plants

bullIncreasing the temperature amp pressure in a steam turbine increases the efficiency of the Rankine steam cycle used in power generation

bullIt decreases the amount of fossil fuel consumed and the emissions generated

bullLarge amount of carbon-di-oxide (CO2) emissions produced by them which contribute in a large measure to greenhouse effect and global warming

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bull Energy in general and electricity in particular plays a vital role in improving the standard of life everywhere

bull World has abundant proven reserves of coal and thus coal-based thermal power plants dominate almost everywhere

bull Energy conversion efficiency of steam turbine cycle can be improved by increasing the main steam pressure amp temperature

Environmental IssuesPrimary sources of energy consisted of Petroleum 360 Coal 274 Natural gas 230 Amounting to an 864 share for fossil fuels in primary energy consumption in the world

World energy consumption was growing about 23 per year

The burning of fossil fuels produces around 213 billion tonnes (213 gigatonnes) of Carbon dioxide (CO2) per year

Environmental Issues

Source Coal Information 2006rsquo


bull Source Assessment of Generation Technology through Lifecycle CO2 Emissions by Power Systems Central Research Laboratory (2000) bull Source Assessment of Generation Technology through Lifecycle CO2 Emissions by Power Systems Central Research Laboratory (2000)

Environmental Advantages

At supercritical pressures (above 3200 psi221 MPa) steam turbine efficiency improves significantly

compared to the typical subcritical cycle This efficiency improvement leads to reductions infuel input emissions output

extra greenhouse

A simple word equation for this chemical reaction is


where stoichiometric coefficients x and y depend on the fuel type A simple example is the combustion of coal (taken here as consisting of pure carbon)C + O2 CO2In words carbon + oxygen carbon dioxide

A coal-fired thermal power station

1 Cooling tower 2 Cooling water pump 3 Transmission line (3-phase) 4 Unit transformer (3-phase) 5 Electric generator (3-phase) 6 Low pressure turbine 7 Condensate extraction pump 8 Condensor 9 Intermediate pressure turbine 10 Steam governor valve 11 High pressure turbine 12 Deaerator 13 Feed heater 14 Coal conveyor 15 Coal hopper 16 Pulverised fuel mill 17 Boiler drum 18 Ash hopper 19 Superheater 20 Forced draught fan 21 Reheater 22 Air intake 23 Economiser 24 Air preheater 25 Precipitator 26 Induced draught fan 27 Chimney Stack

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bull Supercritical power plants are highly efficient plants with best available pollution control technology

bull Reduces existing pollution levels by burning less coal per megawatt-hour produced capturing the vast majority of the pollutants

bull Increases the kWh produced per kg of coal burned with fewer emissions

bull Coal-fired Supercritical Power plants operate at very high temperature [580degC temp] amp with a pressure of 23 MPa)

megapascals (MPa = Nmm2) or gigapascals (GPa = kNmm2)

bull Resulting much higher heat efficiencies (46) as compare to Sub-Critical coal-fired plants

bull Sub-Critical coal-fired plant operates at 455degC temp and efficiency of within 40

Benefits of advanced supercritical power plants include

a) Reduced fuel costs due to improved plant efficiency

b) Significant improvement of environment by reduction in CO2 emissions

c) Plant costs comparable with sub-critical technology amp less than other clean coal technologies

d) Much reduced NOx SOx and particulate emissions

e) Can be fully integrated with appropriate CO2 capture technology

Supercritical technology and its advantages

bull Techno-economic benefits along with its environment-friendly cleaner technology more and new power plants are coming-up with this state-of-the-art technology

bull As environment legislations are becoming more stringent adopting this cleaner technology have benefited immensely in all respect

bull LHV (lower heating value) is improved (from 40 to more than 45)

bull One percent increase in efficiency reduces by two percent specific emissions such as CO2 NOx SOx and particulate matters

bull Supercritical is a thermodynamic expression describing the state of a substance where there is no clear distinction between the liquid and the gaseous phase (ie they are a homogenous fluid)

bull Water reaches this state at a pressure above 221 MPa

bull The greater the output of electrical energy for a given amount of energy input the higher the efficiency

bull If the energy input to the cycle is kept constant the output can be increased by selecting elevated pressures and temperatures for the water-steam cycle

bull Increased thermal efficiency observed when the temperature and pressure of the steam is increased

bull By raising the temperature from 580degC to760degC and the pressure out of the high pressure feed-water pump from 33 MPa to 42 MPa the thermal efficiency improves by about 4

(Ultra-supercritical steam condition)

Super Critical means no distinction between water amp steam

Critical point of water-steam 22115 MPa 37415

Definition of SC and USC Unitsbull Sub-critical units Main steam pressure lt 22115MPa

bull Super-critical units Main steam pressure gt 22115MPa

bull Ultral-supercritical unitsbull Commercial concept means higher steam pressure and temperature than supercritical units

bull 1048766 Japan Main steam pressure gt242MPa

bull or Steam temperature reaches 593

bull 1048766 Denmark Main steam pressure gt275MPa

bull 1048766 China Main steam pressure gt27MPa

Supercritical and USC Coal-fired Units

bull Over 600 super-critical coal-fired units (SC) have been under commercial operation worldwide of which over 60 units are

bull ultra-supercritical units (USC)bull Net plant efficiency achievedbull Sub-critical units(166MPa538538) 38~ 40

bull Supercritical units (24MPa566566) 40~42

bull Ultrasupercritical units (25~30MPa600600)43~46

bull To improve the steam parameters and develop large capacity units are the main measures for the improvement of overall plant efficiency

Effects of Supercritical Steam Parametersto Turbine Heat Rate

bull For every 1 MPa improvement of main steam pressure turbine heat rate could be reduced by 013~015

bull For every 10 improvement of main steam temperature turbine heat rate could be reduced by 025~030

bull For every 10 improvement of reheat steam temperature turbine heat rate could be reduced by 015~020

Supercritical coal-fired power plant

bull Advanced technology for power generation is for achieving higher efficiency clean and safe overall environment

bull Coal continues to be a major energy source for power producers worldwide

bull As carbon consciousness becomes more prominent technologies for gaining efficiency and reducing emissions from coal-fired plants become more important

bull That is one reason why supercritical and ultrasupercritical boiler technologies are reemerging as new materials and designs help drive higher efficiency levels and ease of operation

For your kind attention

THERMAL POWER PLANT- COAL BASED Super Critical Power Genera

This advanced technology for power generation is for achieving

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Definition of SC and USC Units


Effects of Supercritical Steam Parameters to Turbine Heat Rate


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This advanced technology for power generation

is for achieving

bull Higher Efficiency bull Clean bull Safe Overall Environmentbull The development of coal fired supercritical power plant technology can be described as an evolutionary advancement towards greater power output per unit and higher efficiency





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Future Guidelines for Environmental Benefits

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