1

CHAPTER 1

INTRODUCTION

1.1. Company Profile

FACT (Fertilizers And Chemicals Travancore limited) was setup in 1944 on the bank of river

Periyar at Udyogamandal, Ernakulum, with an initial investment of Rs 250 crore as the first large

scale nitrogenous fertilizer factory of India. Today it is the largest public sector institution of the

state.

In 1962, FACT came under the Govt. Of India. A second fertilizer production unit called

Cochin division at Ambalamugal and two engineers divisions, FEDO and few were established.

Products like factomfos, urea etc gained wide popularity. Next turning point in the history of FACT

came with the setting up of Petrochemical division in the 80’s.Caprolactum produced here is of

international standards and is mainly used in the production of nylon. FACT’s next endeavour was

the 900 TPD Ammonia plant, which was setup in Udyomandal with collaboration.

The present turnover of the FACT is about 9000 millions. The company also exports

fertilizers and chemicals for about 50 crore. About 8000 employees are working in various wings of

FACT. (The main plants in Cochin division are Ammonia, Urea, NDC, Sulphuric acid, Phosphoric

acid and Thermal plant).

The three production drives of FACT are Udyogamandal divisions, Cochin divisions and

Petrochemical divisions.

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1.2. Objective

Basically here after combustion of sulphur with air produces a gas mixture of sulphur

dioxide. Catalytic oxidation of sulphur dioxide to produce sulphur trioxide. The absorption of

sulphur trioxide with water to produce sulphuric acid.

The aim of this project is to upgrade the existing SO2 Acid plant LURO BURNER PLC

based interlock system into a newer PLC. According to the program burned into the PLC, it is

supposed to produce safety conditions for the burning of sulphur in the furnace with the help of

LURO BURNER. There are conditions like boiler drum water level, main air pressure, speed of

motor driven LURO BURNER, flow rate of primary air supply etc, which are the critical conditions

that must be satisfied before pumping sulphur into the LURO BURNER from the clean sulphur kit.

In order to assure safe and complete burning of sulphur, the furnace temperature must be

raised to the optimum levels. So as to gradually build up the optimum temperature level, kerosene

firing is employed. Kerosene firing also contains critical steps like timed opening of solenoid valve,

detection of pilot pump using PLC so as to ensure operation. PLC used here is OMRON SYSMAC

CPMIA.

3

CHAPTER 2

PROCESS AND PLANT DESCRIPTION

2.1. Process Features

The basic features involved in the manufacture of sulphuric acid by the contact process may

be summarized as:

The combustion of sulphur with air to produce a gas mixture of sulphur dioxide and oxygen

in the described ratio

S+O2

Catalytic oxidation of sulphur dioxide to sulphur trioxide

SO2+1/2 O2

The absorption of SO3 with water in 98.5% sulphuric acid to produce sulphuric acid.

To get SO2 for ASCL , gas after storage is cooled, scribed with 98.5 acid to remove traces of SO3

and sent to ASCL plant.

2.2. Plant Description

2.2.1. Sulphur Handling

Sulphur from the godown is fed to either of the two sulphur feed hoppers by means of a pay

loader. Sulphur from the both bins is taken to sulphur charging bin by conveyors. Sulphur from bin

is taken to melting pit by conveyors.

2.2.2. Sulphur Melting

Sulphur Melters

Sulphur melters are either above ground tanks or in ground pits with steam coils for

melting the sulphur. The tank or pit may be fitted with an agitator which will increase the melting

rate. Solid sulphur is generally delivered from a storage hopper to the melting tank or pit by a

conveyor system. At this time lime may be added to neutralize any acidity in the sulphur to

minimize corrosion of equipment. Each percent of water in the sulphur will increase the heatload by

approximately 20%.

4

Melting Tanks

Melting tanks are generally plain carbon steel lined with acid resistant brick. Tanks should

be equipped with an overflow to discharge any foam generated when the sulphur is melted. A drain

should be installed at the low point of the tank.

Melting Pits

A melting pit is generally rectangular and is made of reinforced concrete lined with acid

resistant brick. Unlined concrete pits are unsatisfactory. The concrete slowly disintegrates because

it is attacked by sulphuric acid, small amounts which will be present in bulk sulphur. As a minimum

requirement, the melting pit walls should be brick lined at the liquid-air interface.

Provision should be made to permit thermal expansion of the pit. Also, the interior surface

of the concrete will be hotter than the exterior surface which will cause cracking of the concrete.

Properly placed reinforcing steel will minimize cracking of the concrete but it is not unusal to find

cracking in concrete melting pits.

Heating/Melting Coils

Melting coils are usually fabricated of 1 1/2” or 2” schedule 80 steel pipe. They should be

located below the minimum sulphur level in order to reduce corrosion. The riser pipes for steam and

condensate should be protected in the region of variable liquid-air interface to prolong their life.

Coils may be fabricated in trombone, helical and other shapes. The use of finned tubes will increase

surface area and enhance heat transfer.

The sulphur combustion furnace consist of a horizontal steel cylinder shell lined inside with

bricks. Sulphur from the clean pit is sprayed by LURO BURNER into the furnace where it is burned

in the presence of dry air to form gas containing 12% SO2 by volume. A major quantity of heat

evolved is due to exothermic reaction is used for steam production in the heat exchanger. Gas enters

the super heater for cooling and there after split into two streams.

5

2.3. Sulphur Combustion

2.3.1. Conversion

2.3.1.1. First stage

One stream of the gas leaving the super heater is taken for the conversion for the acid

production. The gas contains 12% SO2 by volume and is about5000C. This part is diluted with dry

air to bring down the SO2 concentration to about 10% and temperature about 4300. Convertion of

SO2 to SO3 is an exothermic reaction. It is accomplished in the container with the aid of V2O5

catalyst loaded in 4 layers. Inorder to obtain maximum convertion. Certain temperatures at the inlet

of each catalyst bed must be maintained. It is done by cooling the gas between the beds. The gas exit

first layer having a temperature about 6000C is cooled in economiser III to about 4300C. The

reaction heat after second and third layer is removed by heating the gas going to fourth layer, in

intermediate heat exchanger and final heat exchanger respectively.

2.3.1.2. Second stage

To obtain a conversion efficiency of over 99.5% the SO2 content of the gas after the third

pass is removed in the intermediate absorption tower. The SO3 free gas from theintermediate

absorption tower enters the fourth bed catalyst after picking up the required heat from the final heat

exchanger. The final convertion takes place in the fourth layer catalyst raising the total percentage

of convertion to 99.5%. the gas exist the fourth layer catalyst is cooled in economiser II and led to

final absorption tower.

2.3.2. SO2 Production

As already mentioned the gas exit super heater is split into two streams, one going to acid

plant and the other going to SO2 plant. The stream is further cooled to about 1500C in the heat

exchanger and economiser respectively.after this gas moves to scrubbing tower. The scrubbed gas

pressure is boosted SO2 booster blower and is supplied to ASCL plant.

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2.4. Acid Production

The product (98.5% sulphuric acid) is blend of the IAT circulation system from the

discharge of acid circulation pumps. It is cooled in the product acid cooler and taken to the storage

tank.

2.5. Waste Heat Recovery

DM Water is used as boiler feed water in Waste Heat Recovery System and for dilution of

concentrated Sulphuric Acid in Process Acid Tank.

DM Water from DM Water Plant is first collected in DM Water Tank from where it is pumped by

Deaerator Feed Water Pumps to Boiler Feed Water Storage Tank through Deaerator. Dissolved

gases are removed in Deaerator using saturated steam at a pressure of 0.5 kg/cm² g from Pressure

Reducing Station.

Pressure of steam from Steam Drum is first reduced to 8 kg/cm² g through Pressure

Reducing Station after which part of the steam is sent to Sulphur Melting Pit and remaining

quantity of steam is sent to Pressure Reducing Station where after reducing its pressure to 0.5

Kg/cm² (g), steam is sent to Boiler Feed Water Storage Tank & to Steam Condenser. Steam

Condensate from Condensor is then taken into Condensate Tank from where it is pumped to the

DM Water Storage Tank with the help of Condensate Return Pumps for reusing as boiler feed

water.

2.6. Auxiliary Facilities

2.6.1. Fuel Oil Burning Systems

A separate furnace and heat exchange system is used to preheat the acid plant contact

system as well as preheating combustion air for the regeneration furnace during normal operation.

The preheat system consists of a furnace, heat exchanger; combustion air and tempering air fan

and stack. Natural gas or fuel oil is typically burned in the furnace and tempering air or recycle

gas is added to cool the combustion gases to a suitable temperature before entering the heat

exchanger. Heat is exchanged between the combustion gas and process gas before being

discharged from a local stack.

7

Preheat systems are used for startup and on-line applications. Startup preheaters provide

necessary heat to raise the catalyst bed to its ignition temperature and heat other equipment prior

to introduction of SO2 gas and as such do not operate continuously.

2.6.2. Cooling tower system

Industrial cooling towers can be used to remove heat from various sources such as

machinery or heated process material. The primary use of large, industrial cooling towers is to

remove the heat absorbed in the circulating cooling water systems used in power plants, petroleum

refineries, petrochemical plants, natural gas processing plants, food processing plants, semi-

conductor plants, and for other industrial facilities such as in condensers of distillation columns, for

cooling liquid in crystallization, etc. The circulation rate of cooling water in a typical 700MW coal-

fired power plant with a cooling tower amounts to about 71,600 cubic metres an hour (315,000 U.S.

gallons per minute) and the circulating water requires a supply water make-up rate of perhaps 5

percent (i.e., 3,600 cubic metres an hour).

A cooling tower serves to dissipate the heat into the atmosphere instead and wind and air

diffusion spreads the heat over a much larger area than hot water can distribute heat in a body of

water. Some coal-fired and nuclear power plants located in coastal areas do make use of once-

through ocean water. But even there, the offshore discharge water outlet requires very careful design

to avoid environmental problems.

Petroleum refineries also have very large cooling tower systems. A typical large refinery

processing 40,000 metric tonnes of crude oil per day (300,000 barrels (48,000 m3) per day)

circulates about 80,000 cubic metres of water per hour through its cooling tower system.

2.6.3. Demineralization unit

Demineralization is the Process of removing the mineral salts from water by ion-exchange.

Impurities that remains dissolved in water dissociate to form positive and negative charged particles

known as ions. These impurities or compounds are called electrolytes. Generally, all natural water

has electrolytes in varying concentrations. An ion-exchange vessel holds ion-exchange resin of the

required type through which water is allowed to pass. The selective ions in the water are exchanged

with ions or radicals loosely held by the resin. In this way, the water is passed through several

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vessels or a mixed bed vessel so that both positive and negative ions are removed and water is

demineralization.

2.6.4. Instrument air compressor

It is the name given to the compressor depending upon the application of air, compressed

air is used for actuating the solenoid valve, control valve, moving hydraulic cylinder, cleaning of

column, flushing of columns (distillation). Compressed air is generally passing through after cooler,

moisture trap, heater and alumina air dryer (adsorption type). There are two main types of

compressed air systems: oil-free and lubricated.

9

CHAPTER 3

PROCESS DIAGRAM

3.1. Process Block Diagram

Fig No.3.1.Process block diagram

10

3.2. P&I Diagram

851/1B

Luro burner 581

xas

ssl

zsb

M

LPG s

Burner control system

To motor of sulphur burner pump

To/from luro burner motor

From level steam drum

to/from main air blower

To/from primary air blower

F1

v-268

n

T

F

F1

v-205

104-AR-250 Process air

Instrument air

From clean sulphur pit

v-201

119-AR-15

118-AR-6

V-265

Kerosine oil

Fig No.3.2.P&I diagram

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3.3. Gas SO2 Section

Fig No.3.3.Gas SO2 section

12

CHAPTER 4

OPERATING INSTRUCTIONS FOR THE SULPHUR BURNER

Preparation of heat generator.

Prepare the heat generator (boiler, combustor, etc) for operation in accordance with the

indications of the manufacturer.

Preparation of burner.

Removing the blanking plate from the burner opening of the air register.

Pull of the protective hood of the rotator cup from the cup shroud of the burner. Dismount

the sulphur cup shroud and install the start-up cup shroud.

Move the burner into its operational position and lock it.

Starting the oil supply system.

Open all manually operated shut-off valves in the oil piping. If necessary, set the change-

over/ three-way plug valves of the pumps and strainer group of that fuel oil service pump

which will be in use.

Close the manual rapid shut-off valve and the shut-off valves upstream of the burner.

The fuel operating pressure should be approximately 1-25 bars upstream of the burner. Since

the fuel oil operating pressure has an essential influence on the control behaviour of the

plant, an exact determination of the fuel oil operating pressure is necessary when the plant is

initially adjusted.

Open the manual rapid shut-off valve and the manual shut-off valves upstream of the burner.

The plant is now ready to start.

Preparation of ignition and operation.

Switch ON the burner controller.

Bring the emergency switch to operating position.

Switch ON at least for combustion air fan, burner motor, primary air fan.

Actuate the oil pre-heating switch.

If the trouble signal lamp lights up, actuate the ‘reset’ push button.

Open the air damper in the combustion air duct manually.

Indication “open air damper for purge”.

When the indication end of purge appears, bring the damper in the compression air duct

manually in the minimum position (switch) ZSB-2004.

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Automatic ignition release for ignition transformer and electrical ignition valve (uv-u002)

ignition.

The ignition flame is provided.

The ignition flame is provided by the flame system XAS-X001 and uv-u003, local in caution

main valve open.

Burner is in heating up operation.

4.1. Start Up Operation

The information and procedures indicated below outline the preliminary work of preparing

the plant utilities for start up. Each operator should be familiar with the general instructions for

start up and operation of the plant and operation of individual equipments. For the operation and

maintenance of individual equipments mainly running machinery, reference is made to the

separate manuals provided by the suppliers of these equipments.

The gland of all pumps and valve should be checked for proper working.

All the valves and clampers should be tested to ensure that they can be readily opened and

closed.

All the equipments and pipelines should be free from scales, dust water and debris.

Lubrication of machinery must be thoroughly inspected.

Direction of rotation of motion should be checked.

Trial runs of individual machines should be made to ensure satisfactory performance.

Instruments should be tested for mechanical condition and they must be ready for

operation. Instrument airlines must be free from moisture and dust.

IAT, FAT, GST &ADT must be filled with sufficient concentrated sulphuric acid and

circulates should be carried out through the system and branch lines.

The waste heat boiler system should be filled with properly conditioned water.

Sulphur Melting & Filteration

Steam should be gradually admitted to all the steam heating coils of the sulphur pits and

the jackets. Steam is also to be admitted to the packets of the installed sulphur pumps in

the mixing and clean sulphur pits. All condensate should be drained out.

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Check that correct steam pressure are maintained viz.6kg/cm2g for melting pit and

3.5kg/cm2g for all others. Check all the steam coils for any leak again and ensure the

satisfactory performance of all steam traps.

Start charging solid sulphur gradually into the melting pit till the molten sulphur level in

the pit reaches the top of the agitator blades. Rotate the melting pit agitator by hand to see

if it is free and if free, start agitator, continue charging sulphur to the melting pit. Molten

sulphur overflows into the mixing pit after filling the melting pit.

Furnace Drying And Heating Up

For the initial start up, the brick inside the combustion furnace must be dried very slowly and

for this, it is advisable that a wood fix be lighted inside the furnace and this heat can be utilized to

dry out the furnace. Combustion gas may be vested off through the vent dummy at super heat

outlet till furnace temperature reaches about 3000 °C.

Valves at preheater (514) tube side inlet, shell side inlet and shell side outlet to be closed.

Converter inlet valve and dilution air valve closed.

After 2 or 3 days of wood firing, the LURO BURNER and its accessories should be

mounted. After wood firing and before kerosene firing furnace and boiler/S.H system

should be cleaned of fly ash, particulate matter.

The boiler system should be ready and filled in with deaerated water, prior to this, the DM

unit and deaerators should be lined up.

Start the main air blower and open and adjust its discharge valve to achieve the minimum

.required flow of air.

Light Luro Burner with kerosene oil as per manufacturer’s instructions.

Gradually raise the flow of air and oil to achieve the heating of the furnace as per the

heating up program.

If flame is extinguished, then the flame scanning device in Luro Burner system sends

signal from burner control system to stop oil flow, but operator should also immediately

check and ensure that the oil flow has actually stopped.

Total quantity of oil required during all the 18 days will be of the order of 34,000kg.

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Converter Heating Up

When the temperature inside the furnace reaches around 600 °C the starting vent dummy

at super heater outlet may be closed and preheater may be serviced. The oil firing will have to be

interrupted for this purpose. The position of dummies, slip plates and valves at this time should be

as follows:

Slip plates maintained in converter inlet duct, duct to SO2 plant and duct from 600 TPD

DCDA plant.

Converter inlet valve to be opened.

Dilution air valve to be closed.

Shell side inlet valve of preheater to be opened.

Undried air inlet to be opened and dry air inlet valve near combustion furnace is to be

closed.

Slip plate indirect heating line to fourth bed to be removed, slip ring to be introduced and

valve in the same line to be opened.

Vent dummy at FHE tube side inlet to be opened and slip plate at shell side outlet of IHE

to be inserted.

Vent dummy at economiser outlet duct to be opened.

It may be noted that only dry air is to be used to heat catalyst bed.However,when the

lowest temperature at any point in the converter is more than 100 °C undried air may be

used if there is difficulty in supplying dry air during the first start up of the plant.

The required flow of air through the system is achieved by adjusting the air valves at

combustion furnace inlet, blower discharges and 4th bed direct heating line.

Boiling out operation of the boiler is to be complicated during this period if not already

complete.

Charging Sulphur

When the required temperature is achieved in the combustion furnace and converter, the

plant is ready for charging sulphur. The change over to sulphur is carried out as quickly as

possible to avoid heat loss.

Shut off the oil supply. Purge the system for a few minutes with air and stop the air

blower.

Blank flanges, slip plates and valves are to be adjusted as follows:

16

All vent dummies are to be closed.

Preheater shell side inlet and outlet and tube side inlet valves to be closed.

Slip plates at converter inlet and duct to SO2 plant to be removed and slip rings to be

introduced.

Duct form 600 TPD DCDA plant to be kept slip plated.

Dilution air valves to be kept closed initially and to be adjusted as required.

Converter inlet valve and valve to SO2 plant to be opened and adjusted as required.

Slip plate to be introduced in 4th bed direct heating line and slip plate to be removed from

IHE shell side outlet.

Wet air valve to be closed.

Fuel oil valve to be closed and as additional safeguard oil line may be disconnected.

Dilution air valve to stack may be opened and adjusted suitably if there is excess air after

meeting process air requirements.

Clean the sight glass of the furnace if necessary.

Start the main blower and adjust discharge valve and combustion furnace inlet valve to get

a flow of about 60% of its rated capacity.

Start the sulphur burner pump and adjust the bypass valve to get required.

4.1.1. Sulphur Operation

Ready the oil firing and actuate the oil preheated switch.

The electromagnetic oil valves uv-u001 and uv-u003 close automatically.

Close the manual rapid shut-off oil valve.

Switch off two fans as well as the burner.

Close oil valves. Remove the burner from the furnace opening.

Switch the blanking plate into the furnace operation.

Dismount the pilot burner and the flame scanner and blank of the opening.

Dismount the start up cup, mount the sulphur cup.

Swing out the blanking plate, move the burner leads operation, position and lock manually

by doing so electrical interlock is effected at the same time.

Switch on the burner motor.

Release the main sulphur valve.

Sulphur burning.

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4.1.2. Sulphur Combustion Furnace Details

Table No.4.1.2.1. Sulphur combustion furnace details

Service To burn the sulphur kerosene during start

up, SO2 and to burn.

Type Horizontal, Cylindrical

Dimensions

Length:5419mm

Diameter at burner inlet:1120mm

ID(shell):2900mm

Net ID(after brick lining):1976mm

Front Cone Angle:45deg

Diameter of rare portion:1476mm

Normal operation temperature:1115 C

Lining

1st layer (next to shell) -asbestos: 2/5mm.

2nd layer-insulation brick: 125mm.

3rd layer-insulation refractory brick:

125mm.

4th layer-High duty fire clay refractory:

190mm.

Accessories type LURO Burner

Rotary burner

Kerosene oil 400 kg/hr, minimum

Burning capacity 2000kg/hr, maximum

Sulphur burning capacity 7.625T/hr, normal,9.917T/hr, maximum

and 2.375T/hr, minimum

Burner speed 5200rpm

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Primary air 3400Nm3/hr

Secondary air 44600Nm3/hr,at 12% SO2

4.2. Normal Operation

Some the guidelines for the operating personnel during normal operation of plant are given

below:

Temperature at various points

First bed inlet -430 C.

First bed outlet -597 C.

Second bed inlet -440 C.

Second bed outlet -526 C

Third bed inlet -450 C.

Third bed outlet -473 C.

Fourth bed inlet -420 C.

Gas inlet FHE -65 C.

Gas exit FHE -330 C.

Analytical control at various points:

SO2 % inlet converter-10.5%.

Acid to GST, IAT & FAT-98.5%.

Acid to ADT-96.0%.

The boiler must be watched for its water level & stream pressure should be maintained as

per the manufacturer’s instructions.

Measure & record regularly the pressure at various points provided & as certain the

pressure drop across system.

It is essential that frequent analytical tests are carried out for smooth operation of plant

which should include:

%SO2 at converter inlet and stack.

Boiler H2O analysis.

Dissolved O2 in feed water.

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Mist content in gas outlet IAT and FAT.

Acid concentration if ADT, FAT, IAT and GST.

The gas sampling point at the exit of IAT should be opened and checked for the presence

of SO3.Corrective action should be taken to set right acid concentration in IAT since

unabsorbed SO3 can condense on the tubes of FHE and cause damage to the tubes.

Lubricate machinery and instrument as per manufacturer’s advice.

The air filters of the air blowers should be cleaned by compressed air in the reverse

directions when found necessary.

4.3. Shut Down Operation

Emergency Shut Down

Stop the sulphur pump.

Stop SO2 blower first and then main air blower.

Stop dilution H2O.

Stop product bleeding.

Close the blow down valves of the boiler.

Inform strain users about the shutdown of the plant and close the export strain

valve.

If necessary stop acid circulation.

Proceed then with items as in planned shutdown.

Shut Down Due To Power Failure

If the air blower has tripped, immediately check whether the sulphur pump has

tripped if it cannot stop it.

If it is a voltage fluctuation, then the plant can be started immediately.

If it is a power failure, follow the instructions in emergency shutdown.

Ensure the level in the boiler is maintained.

Planned Shut Down For A Short Duration

Notify any stream users involved for the proper authority of the intention to shut

down.

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Raise the temperature through the gas system, so that healing will not be necessary

at the time of start up.

Shut off the dilution H2O to the absorbers and the inter transfer of acid.

Close the main valve in the sulphur pumping line and store the sulphur pump.

Absolute care is to be taken that the stream cooling of the sulphur burner is not

interrupted.

Close the boiler continous blow down valve, stream outlet valve and maintain

normal level in the boiler.

Allow the blower to run for a few minutes to ensure that all the sulphur is burnt and

the system is purged. Then stop the SO2 blower first and then the main blower.

Shut off water to the acid coolers.

Ensure that the levels in the pump tanks are correct and will allow the towers to

drain back without overflowing.

Close all gas and air valves to prevent air flow through the plant and to retain the

heat.

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CHAPTER 5

COMPONENTS USED

5.1. Solenoid Pilot Operated Valve

A solenoid valve is an electromechanical valve for use with liquid or gas. The valve is

controlled by an electric current through a solenoid: in the case of a two-port valve the flow is

switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet

ports. Multiple solenoid valves can be placed together on a manifold.

Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to

shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids

offer fast and safe switching, high reliability, long service life, good medium compatibility of the

materials used, low control power and compact design.

A solenoid valve has two main parts: the solenoid and the valve. The solenoid converts

electrical energy into mechanical energy which, in turn, opens or closes the valve mechanically. A

direct acting valve has only a small flow circuit, shown within section E of this diagram (this section

is mentioned below as a pilot valve). This diaphragm piloted valve multiplies this small flow by

using it to control the flow through a much larger orifice.

Solenoid valves may use metal seals or rubber seals, and may also have electrical interfaces

to allow for easy control. A spring may be used to hold the valve opened or closed while the valve is

not activated.

Fig No: 5.1. Solenoid pilot operated valve

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5.2. Annubar-Differential Pressure Flow Measurement

An annubar is similar to a pitot tube used to measure the flow of gas or liquid in a pipe. The

Pitot tube measures the difference between the static pressure and the flowing pressure of the media

in the pipe. The volumetric flow is calculated from that difference using Bernoulli's principle and

taking into account the pipe inside diameter.

The biggest difference between an annubar and a pitot tube is that an annubar takes multiple

samples across a section of a pipe or duct. In this way, the annubar averages the differential

pressures encountered accounting for variations in flow across the section. A pitot tube will give a

similar reading if the tip is located at a point in the pipe cross section where the flowing velocity is

close to the average velocity.

Annubar is a registered trade name with Emerson Process Management / Rosemount.

Fig No.5.2.Annubar differential pressure flow meter

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5.3. Flame Detector Photovoltaic Cell

This is an important class of photo detectors. They generate a voltage which is proportional

to EM (Electro Magnetic) radiation intensity. They are called photovoltaic cell because of their

voltage generating characteristics. They are passive transducers i.e; they do not need an external

source to power them.

The cell is giant diode, constructing a PN junction between appropriately doped

semiconductors. Protons striking the cell pass through the thin P-doped upper layer and are absorbed

by the electrons in the lower N layer, causing formation of conductin of electrons and holes. The

depletion zone potential of the PN junction then separates these conduction holes and electrons

causing a difference of potential to develop across the junction.

The open circuit voltage is given by,

E0=Ec logeEe: V

Where, Ec=Calibration voltage; V

Ee=Radiant incidence/m2

All photovoltaic cells have low but finite internal resistance. When connected to a circuit

having some load resistance, the cell voltage is reduced somewhat from the value given by the above

equation.

The photovoltaic cells can operate satisfactorily in the temperature of 100 to 1250C. The

temperature changes have little effect on short circuit current but affect the open circuit voltage

considerably. These changes may be of the order of a few mV/0C.

5.4. Pressure Switches

Pressure switches are used to energize and de-energize electrical switches as function of

relationship between the process pressure and the predetermined set point. They are available to

detect absolute compound gauge and differential pressure with accuracies up to ½% of a span. The

24

electrical switches assemblies are either snap acting mechanical micro switches or mercury switches.

Pressure range within which the the actuation point can be referred to as adjustable range.

The set point is the pressure that actuates the switch to open or close and the electric circuit

pressure switched. The electrical rating of the pressure switches at its operating level varies from

10amps on AC or DC circuits.

Fig No.5.4.Pressure switch

5.5. Float Switches

A float switch is a device used to sense the level of liquid in a tank. The switch may actuate

a pump, an indicator, an alarm or other device.

Float switches range from small to large and may be as simple as a mercury switch inside

the hinged float or as complex as a series of optical or conductance sensors producing discrete

output as the liquid reaches many different levels within the tank. Perhaps the most common type of

float switch is simply a float raising a rod that actuates a micro switch.

A very common application is in sump pumps and condense pumps where the switch

detects the rising level of liquid in the sump or tank and energizes an electrical pump which then

pumps liquid out until the level of the liquid has been substantially reduced at which point the pump

is switched off again. The float switches are often adjustable and can include substantial hysteresis.

i.e., the switch’s turn on point may be much higher than the shut off point. This minimises the on-off

cycling of the associated pump.

25

Some float switches contain a two stage switch as liquid level rises to the trigger point of

the first stage, the associated pump is activated. If the liquid continues to rise (perhaps because the

pump has failed or it’s discharged is blocked), this second stage will be triggered. This stage may

switch off the source of the liquid being pumped, trigger an alarm or both.

A very common application is in sump pumps and condensate pumps where the switch

detects the rising level of liquid in the sump or tank and energizes an electrical pump which then

pumps liquid out until the level of the liquid has been substantially reduced, at which point the

pump is switched off again. Float switches are often adjustable and can include substantial

hysteresis. That is, the switch's "turn on" point may be much higher than the "shut off" point. This

minimizes the on-off cycling of the associated pump.

Fig No.5.5.1.Float switch

26

Fig No.5.5.2.Float switch

5.6. Electronic Pressure Transmitter

The FCX-All series transmitter detects the differential pressure of various fluids, convert it

into a current signal of 4 to 20mA DC and transmit. All the adjustment functions are in corporate in

the transmission unit for making adjustment easily and exactly. Transmission setting(such as range

and damping time constant) can be changed from an HHC(handheld communicator).

Principle

The operating principle of the FCX-All series transmitter is shown in the block diagram.

The input pressure is changed into an electrostatic capacitance in the detecting unit. The proportional

to the pressure under goes conditioning and amplification in the transmission unit, and is then output

as a current of 4to 20mA DC.

27

Fig No.5.6.Electronic pressure transmitter

5.7. Inductive Type Proximity Speed Sensor

In automated processes sensors are used to provide signals on positions and limits, serve as

pulse pick-ups for counting task or for monitoring rotational speed. Inductive proximity sensors are

indispensible for these type of applications. As compared to mechanical devices, they offer ideal

features: on contact detection of all metals, high switching frequencies, accuracy, and durability in

the most aggressive environments. They are the intensive to vibrations, dust and moisture.

Inductive proximity sensors take advantage 0 changes in resonant circuit caused by the

eddy current losses in the conductive material. An inductive proximity sensor contains four essential

components: a coil wire wrapped in a ferrite core, an oscillator circuit, an evaluation circuit and an

output circuit. When a voltage is applied to sensor, an oscillating current flows through the coil and

radiates an electromagnetic field from the active face of the sensor. The field is directed and shaped

by the ferrite core.

When an electrical conductor or metal target enters the electromagnetic field, eddy current

are drawn from the oscillator and induced into the target. The eddy current draw energy from the

electromagnetic field. The losses in energy caused by the eddy current are due to the conductivity

and permeability of the target, the distance and position of the target, and the size and shape of the

target.

28

When the metal target is positioned at the precise distance from the active face of the

sensor, the energy loss caused by the eddy current becomes so large that the amplifier cannot output

sufficient energy to maintain oscillation and magnetic field collapses. The breakdown in oscillation

is detected by the evaluation circuit, which then changes the changes the states of the output circuit.

Fig No.5.7.Inductive type speed sensor

5.8. Relays

Relays may be said as electromagnetic switches. When a voltage is applied to coil a

magnetic field is generated. The magnetic field is sucks the contact of the relay in causing them to

make a connection. This contact can be considered as a switch. They allow current to flow between

two points thereby closing the circuit.

Working of a Relay

Relay consists of mainly 3 parts:

Coil Base Contacts

There are three types of contacts:

Normally Closed (NC) Normally Open (NO) Common

When the coil is energised it act as an electromagnet and it attracts the common contact thus

the condition will change that NC will change to NO and vice versa.

29

In this study circuit electrical relays are used of coil supplying 110V. A relay act as switch.

This relay has 3 NC, 3 NO, 3 common contacts, 2 coil contacts are there in this type of relay.

Pin Number 2&10 are used to energise the coil.

Pin Number 4, 5 & 8 are normally closed contacts.

Pin Number 1, 6 & 11 are common contacts.

Pin Number 3, 7 & 9 are Normally Open contacts.

When supply is given to the coil produces a magnetic field it attracts the common terminal

towards the coil. As result common terminal touches contacts 3, 7& 9 So the contact condition

reverse that is the NO at de-energized condition becomes NC and NC becomes NO. At energized

condition we use these NO & NC contacts according to our requirement when it acts as an inter

posing relay.

The relay base used has 11 terminals of which 2 & 10 coil supply, 4,5 & 8are contacts, 1,6

& 11 are common terminals,3,7 & 9 are normally open contacts. The relay is inserting to the base.

The appropriate contacts are taken from the relay base.

Fig No.5.8. Relay

30

5.9. Luro Burner

The Luro burner developed in co operation with Saacke is the first choice in sulphur

combustion technology because of its flexibility from turn down ratio to operation modes, the

superior atomization and its reliability.

The liquid sulphur combustion technology because of its flexibility from turn down ratio to

operation modes, the superior atomization and its reliability.The liquid sulphur is fed into the Luro

burner at virtually atmospheric pressure thereby avoiding the need for costly high pressure pumps

and piping. The spinning cup, rotating at high speed, ensures excellent atomization of sulphur. A

system of adjustable guide vanes imparts a tangential component to the combustion air. the resulting

spiral path of the gases through the furnace not only effectively keeps the flame central but

simultaneously prevents unvapourized sulphur droplets from impinging on the furnace wall.

Fig No.5.9.Luro burner

31

CHAPTER 6

PROGRAMMABLE LOGIC CONTROLLER

The only (or rather the best) way to control a production machine, or any other type of

machine for that matter, was to make up a circuit with something called relays.

All these relays had to be hard wired together in the right order in a control panel to make

the machine operate in the desired manor. This style of control panel gave rise to several problems,

as the relays were electromechanical they failed far too often. Coil failure and contact wear were

difficult to diagnose and replace, also if a circuit change was needed that called for an extensive

rewire of all the involved relays.

Fig No.6.1.1.Programmable logic controller

After the PLC took off, which didn't take very long given the advantages, Bedford

Associates changed their name after some time to Modicon PLC and eventually became the first

supplier of PLC’s.

32

Fig No.6.1.2.PLC Ladder program/relay schematic

This is why PLC history is so deeply rooted in this relay schematic layout, the Ladder

Logic (as it’s now called) schematic style of operation was copied into the PLC programming

software as a basis of programming.

Fig No.6.1.3.PLC Ladder programmer

Some PLC’s only have as little as 6 inputs and outputs (referred to as I/O) in total to

control, One single PLC processor is capable of controlling just one process or a whole

manufacturing empire, even internationally. One main processor would then control others that do

the local work and report back to the main controlling PLC processor.

A programmable logic controller(PLC), or programmable controller is a digital controller

used for automation of industrial processes, such as control of machinery on factory assembly lines.

33

Unlike general purpose computers, the PLC is designed for mutiple inputs and output arrangements,

extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact.

Programs to control machine operation are typically stored in battery-backed or non-volatile

memory. A PLC is an example of a real time system since output results must be produced in

response to input conditions within a bounded time, otherwise unintended operation will result.

6.1. Features

The main difference from other computers is that PLCs are armoured for severe conditions

(such as dust, moisture, heat, cold) and have the facility for extensive input/output (I/O)

arrangements. These connect the PLC to sensors and actuators. PLCs read limit switches, analog

process variables (such as temperature and pressure), and the positions of complex positioning

systems. Some use machine vision. On the actuator side, PLCs operate electric motors, pneumatic or

hydraulic cylinders, magnetic relays, solenoids, or analog outputs. The input/output arrangements

may be built into a simple PLC, or the PLC may have external I/O modules attached to a computer

network that plugs into the PLC.

Scan time

A PLC program is generally executed repeatedly as long as the controlled system is

running. The status of physical input points is copied to an area of memory accessible to the

processor, sometimes called the "I/O Image Table". The program is then run from its first instruction

rung down to the last rung. It takes some time for the processor of the PLC to evaluate all the rungs

and update the I/O image table with the status of outputs.

Special-purpose I/O modules, such as timer modules or counter modules, could be used

where the scan time of the processor was too long to reliably pick up, for example, counting pulses

from a shaft encoder. The relatively slow PLC could still interpret the counted values to control a

machine, but the accumulation of pulses was done by a dedicated module that was unaffected by the

speed of the program execution.

System scale

A small PLC will have a fixed number of connections built in for inputs and outputs.

Typically, expansions are available if the base model has insufficient I/O. Modular PLCs have a

34

chassis (also called a rack) into which are placed modules with different functions. The processor

and selection of I/O modules are customized for the particular application. Several racks can be

administered by a single processor, and may have thousands of inputs and outputs. A special high

speed serial I/O link is used so that racks can be distributed away from the processor, reducing the

wiring costs for large plants.

User interface

PLCs may need to interact with people for the purpose of configuration, alarm reporting or

everyday control. A human-machine interface (HMI) is employed for this purpose. HMIs are also

referred to as man-machine interfaces (MMIs) and graphical user interface (GUIs).

Communications

PLCs have built in communications ports, usually 9-pin RS-232, but optionally EIA-485 or

Ethernet. Modbus, BACnet or DF1 is usually included as one of the communications protocols.

Most modern PLCs can communicate over a network to some other system, such as a

computer running a SCADA (Supervisory Control And Data Acquisition) system or web browser.

Programming

PLC programs are typically written in a special application on a personal computer, then

downloaded by a direct-connection cable or over a network to the PLC. The program is stored in the

PLC either in battery-backed-up RAM or some other non-volatile flash memory. Often, a single

PLC can be programmed to replace thousands of relays.

Digital and analog signals

Digital or discrete signals behave as binary switches, yielding simply an On or Off signal (1

or 0, True or False, respectively). Push buttons, limit switches, and photoelectric sensors are

examples of devices providing a discrete signal. Discrete signals are sent using either voltage or

current, where a specific range is designated as On and another as Off. Initially, PLCs had only

discrete I/O.

35

Analog signals are like volume controls, with a range of values between zero and full-scale.

These are typically interpreted as integer values (counts) by the PLC, with various ranges of

accuracy depending on the device and the number of bits available to store the data. As PLCs

typically use 16-bit signed binary processors, the integer values are limited between -32,768 and

+32,767. For example, an analog 0 - 10 V input or 4-20 mA would be converted into an integer

value of 0 - 32767.Current inputs are less sensitive to electrical noise (i.e. from welders or electric

motor starts) than voltage inputs.

Example

As an example, say a facility needs to store water in a tank. The water is drawn from the

tank by another system, as needed, and our example system must manage the water level in the

tank.

Using only digital signals, the PLC has two digital inputs from float switches (Low Level

and High Level). When the water level is above the switch it closes a contact and passes a signal to

an input. The PLC uses a digital output to open and close the inlet valve into the tank.

When the water level drops enough so that the Low Level float switch is off (down), the

PLC will open the valve to let more water in. Once the water level rises enough so that the High

Level switch is on (up), the PLC will shut the inlet to stop the water from overflowing.

| Low Level High Level Fill Valve |

|------[/]------|------[/]----------------------(OUT)---------|

| | |

| | |

| | |

| Fill Valve | |

|------[ ]------| |

| |

| |

An analog system might use a water pressure sensor or a load cell, and an adjustable

(throttled) control (e.g. by a valve) of the fill of the tank. In this system, to avoid 'flutter' adjustments

that can wear out the valve, many PLCs incorporate "hysteresis" which essentially creates a

36

"deadband" of activity. A technician adjusts this dead band so the valve moves only for a significant

change in rate. This will in turn minimize the motion of the valve, and reduce its wear.

6.2. PLC compared with other control systems

PLCs are well-adapted to a range of automation tasks. These are typically industrial

processes in manufacturing where the cost of developing and maintaining the automation system is

high relative to the total cost of the automation, and where changes to the system would be expected

during its operational life. PLCs contain input and output devices compatible with industrial pilot

devices and controls; little electrical design is required, and the design problem centers on

expressing the desired sequence of operations.

Very complex process control, such as used in the chemical industry, may require

algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed

or precision controls may also require customized solutions; for example, aircraft flight controls.

PLCs may include logic for single-variable feedback analog control loop, a "proportional,

integral, derivative" or "PID controller". A PID loop could be used to control the temperature of a

manufacturing process, for example. Historically PLCs were usually configured with only a few

analog control loops; where processes required hundreds or thousands of loops, a distributed control

system (DCS) would instead be used. As PLCs have become more powerful, the boundary between

DCS and PLC applications has become less distinct.

6.3. Basic Components of PLC

Programmable controllers have grown throughout industrial control applications because of

the ease they bring to creating a controller: ease of programming, ease of wiring, ease of installation,

and ease of changing. PLCs span a wide range of sizes, but all contain six basic components:

processor or central processing unit (CPU);

rack or mounting;

input assembly;

output assembly;

power supply;

programming unit, device, or PC/software

37

Fig No.6.3.PLC Components

We will start with explaining the physical components you see when looking at a PLC

system - and then explore what goes on inside each part, and how the components relate to each

other.

6.3.1. Rack Assembly

Most medium to large PLC systems are assembled such that the individual components -

CPU, Input/output, Power Supply - are modules that are held together within a rack. In smaller PLC

systems - all of these components may be contained in a single housing or "brick" - these smaller

systems are sometimes referred to as "bricks" or "shoebox" PLCs.

6.3.2. Power Supply

The power supply provides power for the PLC system. The power supply provides internal

DC current to operate the processor logic circuitry and input/output assemblies. Common power

levels used are 24V DC or 120 VAC.

6.3.3. Processor (CPU)

The processor, central processing unit, or CPU is the "brain" of the PLC. The size and type

of CPU will determine things like: the programming functions available, size of the application logic

available, amount of memory available, and processing speed.

38

6.3.4. Input/output Assembly

Inputs carry signals from the process into the controller, they can be input switches,

pressure sensors, operator inputs, etc. These are like the senses and sensors of the PLC.

Outputs are the devices that the PLC uses to send changes out to the world. These are the

actuator the PLC can change to adjust or control the process motors, lights, relays, pumps, etc.

Many types of inputs and outputs can be connected to a PLC, and they can all be divided into two

large groups –

Analog

Digital

Digital inputs and outputs are those that operate due to a discrete or binary change - on/off,

yes/no. Analog inputs and outputs change continuously over a variable range - pressure,

temperature, and potentiometer.

6.3.5. Programming Device

The PLC is programmed using a specialty programmer or software on a computer that can

load and change the logic inside. Most modern PLCs are programmed using software on a PC or

laptop computer. Older systems used a custom programming device.

39

CHAPTER 7

BASIC OPERATION OF A PLC SYSTEM

The operation of the PLC system is simple and straightforward. The Process or CPU

completes three processes: (1) scans, or reads, from the input devices (2) executes or "solves" the

program logic, and (3) updates, or writes, to the output devices.

Fig No.7.1.Basic operation of PLC

7.1. PLC Program

For the PLC to be useful, it must first have a Program or Logic for the CPU to execute. This

logic can be written in Ladder Logic, Instruction List, Sequential Function Charts, or any of the IEC

languages.

The programmer will then download the program to the PLC. This is usually done by

temporarily connecting the programmer to the PLC. Once the program is installed or downloaded to

the CPU - it is usually not necessary for the PC to remain connected.

40

7.2. Basic Scan

Once the program is in the CPU - the PLC is then set to "run", and the PLC executes the

application program repeatedly. In addition to executing the program, the CPU regularly reads the

status of the input devices, and sends data to the output devices. The Input system senses the status

of the real world inputs (a switch, a level, etc.), translates them to values that can be used by the

CPU, and writes those values to the Input table.

This process of reading inputs, executing logic, and writing outputs is called the PLC Scan or

Sweep.

Fig No.7.2.Basic Scan

7.3. Memory

The control program or application program is stored in memory. As the PLC executes

logic, it may also read and store values to memory. The values may also be used and referenced by

the application program.

41

CHAPTER 8

INTRODUCTION TO OMRON SYSMAC CPM1A PLC

The CPM1A is a compact, high speed programmable controller (PC) designed for control

operations in systems requiring from 10-100 points per PC.

OMRON provides one of the robust control systems. The use of PLC improves productivity,

quality, and steamline logistics and gets the products to market faster. OMRON corporation’s

Industrial automation business (IAB)’s global network is recognized worldwide as the leading

supplier of high quality, high technology products. They offer reliable advanced factory

automation systems. Their control components system equipments and advanced networking

technology can be found in manufacturing sites throughout the world supporting the production of

cars, home electronics, food and various other products. OMRON has an enormous range of

innovative products capable of meeting every application requirement and services which can

translate the OMRON sensing and control technology into effective solutions.

42

8.1. General Specifications

Table No.8.1.General specifications

Input type DC input

CPU type 10 point I/O 20 point I/O 30 point I/O 40 point I/O

Power supply

voltage/frequency

AC power

supply 100 to 240VAC,50/60Hz

DC power

supply 24VDC

Operating voltage

range

AC power

supply 85 to 264VAC

DC power

supply 20.4 to 26.4VDC

Power

consumption

AC power

supply 30VA max. 60VA max.

DC power

supply 6 W max. 20 W max.

Inrush current 30A max. 60 A max.

External power

supply(AC only)

Power

supply

voltage

24 VDC

Power

supply

output

capacity

200 mA 300 mA

Insulation resistance 20 MΩ min.at 500 VDC between the AC terminals and the

protective earth terminal.

Dielectric strength

2,300 VAC at 50/60 Hz for one minute with a leakage of 10

mA max. between all the external AC terminals and the

protective earth terminal.

Vibration resistance

10 to 57 Hz with an amplitude of 0.075mm,and 57 to 150 Hz

with an acceleration of 1.5G in the X,Y and Z directions for 10

sweeps of minutes each.

43

Shock resistance 147m/s2 in the X, Y and Z directions 3 times each.

Ambient

temperature

Operating 0 C to 55C (32F to 131 F)

Storage -20 C to 75 C(-4 F to 167 F)

Ambient

humidity Operating 10% to 90% RH no condensation

Ambient

environment Operating With no corrosive gas

Terminal screw size M3

Power supply holding time 10 ms min.for AC models, and 2 ms for DC models

CPU weight AC models 400g max. 500g max. 600g max. 700g max.

DC models 300g max. 400g max. 500g max. 600g max.

Expansion weight

Units with 20 I/O points: 300g max.

Units with 8 output points: 250g max.

Units with 8 input points: 200g max.

MAD01 Analog I/O unit:150g max.

MAD11 Analog I/O unit:250g max.

Temperature sensor units:250g max.

Compo Bus/S I/O link unit:200g max.

Device Net I/O link unit:200g max.

Profibus-DP slave unit:125g

44

8.2. General Characteristics

Table No.8.2.General characteristics

Input type DC input

CPU type 10-point I/O 20-point I/O 30-point I/O 40-point I/O

Control method Stored program method

I/O control method Combination of the cyclic scan and immediate refresh processing methods

Programming language Ladder diagram Instruction word 1 step per instruction, 1 to 5 per instruction

Types of instructions

Basic instruction 14 types

Special instructions 79 types, 139 instructions

Instruction execution

time

Basic instructions 0.72 to 16.2µs

Special instructions MOV instruction =16.3µs

Program capacity 2,048words

Maximum I/O points

CPU only

10 points(6 input/ 4 output points)

20 points (12

input/8 output points)

30 points (18

input/12 output points)

40 points (24 input/16 output points)

With Expansion I/O Module

_ _

Up to 90 points

(54 input/36 output points)

Up to 100 points (60 input/40 output points)

Memory protection Maintains the contents of the HR, AR, Counter and Data Memory Areas.

Memory backup

Flash: User program, data memory (Read only)and PLC setup areas are backed up without a battery.

Super capacitor: Data memory(read/write), holding bits, auxiliary memory bits, counter values, error log area are backed

up by a capacitor for 20-days at an ambient temperature of 25oC.

Self-diagnostic function CPU error (watchdog timer), memory errors , I/O bus errors

Program check No END instruction programming errors (constantly checked during operation)

Pulse output 1 point: 2kHz

High-speed counter

1 point: Single phase at 5kHz or two-phase at 2.5kHz(linear counting method)

Incremental mode: 0 to 65535(16-bit) Decremental mode: -32767 to 32767(16-bit)

45

Quick-response inputs Together with the external interrupt input (minimum pulse width of 0.2ms)

Input time constant Together with the external interrupt input(minimum pulse width of 0.2ms)

Input time constant Can be set at 1ms, 2ms, 4ms, 8ms, 16ms, 32ms, 64ms, or 128ms.

Interrupt processing: External Interrupt

2 points (Response time of 0.3 ms max.)

4 points (Response time of 0.3 ms max.)

Analog settings 2 points:(0 to 200 BCD)

8.3. CPM1A Features

One Piece Construction

The CPM1A CPU units feature a one piece construction including 10, 20, 30 or 40 built in

I/O terminals. All CPU units are provided with relay outputs.

Extra I/O Capacity

Up to 3 I/O units can be connected to a CPM1A-40CDR-D CPU unit to add an extra 20I/O

points for each, for a maximum of up to 100 I/O ports.

Input Filter Function

The CPM1A is equipped with a filter function to prevent incorrect operation caused by

either chatter or noise in the input signal. The user can select an input time constant of 1ms or

128ms.

Low Maintenance Design

Flash memory provides memory backup without a battery.

Input Interrupts

The CPM1A-40CDR-D CPU units can handle 4 interrupt inputs. In addition to the normal

input interrupts, the CPM1A has a counter mode that counts high speed input signals and triggers

interrupts at fixed count multiples.

46

Quick Response Inputs

Quick response inputs can detect input signals with a pulse width as short as 0.2ms

regardless of their timing during the PC cycle. Quick response inputs and interrupt inputs use the

same input terminals.

Interval Timer

CPM1A PC’s have a high speed interval timer which can be set from 0.5ms to

319968ms.The timer can be set trigger a single interrupt(one shot mode)or repeat scheduled

interrupts(scheduled interrupt mode)

High Speed Counter

CPM1A PC’s have a high speed counter that can be used in incremental mode or up/down

mode. The high speed counter can be combined with input interrupts to perform target valve

control or zone comparison control that is not

affected by the PC’s cycle time.

Analog Setting Functions

The CPM1A PC’s have 2 analog volume controls that can be used to make manual and

analog settings.

Host Link Communications

The CPM1A PC’s are compatible with the host link which allows communications with

personal computers. The CPM1A using the host link can also communicate with programmable

terminal using host link commands. An RS232C adapter is used for 1to 1 communications and an

RS422 adapter is used for 1to n communications.

NT Link Communications

High speed operations can be achieved by providing a direct access by connecting the

CPM1A to the OMRON programmable terminal through the NT link interface. An RS232C

adapter is used for this connection.

47

Standard Peripheral Devices

The CPM1A uses the same programming consoles and SYSMAC support software(SSS)

as the C200/HS,C200HX/HE/HG,CPM1,SRM1,CQM1 PC’s.

Programming Is Possible Using PT

Programming operation is possible through the PT screen by using an OMRON PT that

has a built in programming console function.

48

8.4. Terminal And IR Bit Allocation

The following table shows which IR bit are allocated to the I/O terminals on the CPM1A’s

CPU units and expansion I/O unit.

Table No.8.4.Terminal & IR bit allocation

No of

I/O

terminals

on the

CPU unit

CPU Unit

terminals CPU 1A-20 EDR Expansion I/O Unit Terminals

Power

Supply

Model

Number

inputs outputs Inputs Outputs Inputs outputs inputs outputs

40

24

points

00000

to

000011

00100

to

00111

16

points

01000

to

01007

01100

to

01107

12

points

00200

to

00211

8

points

01200

to

01207

12

points

00300

to

00311

8

points

01300

to

00411

12

points

00400

to

00411

8

points

01000

to

01407

AC

CPM1A-

40CDR-

A

CPM1A-

40CDR-

D

49

8.5. CPM1A Flow Chart

Fig No.8.5.CPM1A flow chart

50

8.6. CPM1A Cycle Time

The processes involved in a single CPM1A cycle are shown in the following table, and their

respective processing times are explained.

Table No.8.6.CPM1A cycle time

Process Content Time requirements

Overseeing Setting cycle watchdog timer, I/O bus check, clock refreshing, refreshing bits allocated to new functions,etc.

0.6 ms

Program execution User program is executed. Total time for executing instructions. (Varies according to content of user’s program.)

Cycle time calculation Standby until set time, when minimum cycle time is set in DM 6619 of PC Setup. Calculation of cycle time.

Almost instantaneous, except for standby processing.

I/O refresh Input information is read to input bits. Output information (result of executing program) is written to output bits.

10-point CPU: 0.06 ms 20-point CPU: 0.06 ms 30-point CPU: 0.3 ms Expansion I/O Unit : 0.3 ms

Peripheral port servicing

Devices connected to peripheral port serviced.

0.26 ms min.,5% or less of cycle time up to 66 ms.

51

CHAPTER 9

PROGRAM

Table No.9.1.Program

NO ADDRESS OPERAND 1 0000 LD 0003 2 0001 OUT 20200 3 0002 LD 0004 4 0003 OUT 20201 5 0004 LD 0005 6 0005 OUT 20202 7 0006 LD 20200 8 0007 AND 20201 9 0008 AND 20202 10 0009 OUT 1102 11 0010 LD 0006 12 0011 OUT 1103 13 0012 LD 00105 14 0013 OR 00103 15 0014 OUT 20010 16 0015 LD NOT 20010 17 0016 LD 1002 18 0017 LD 0008 19 0018 OUT 1003 20 0019 LD 0009 21 0020 OUT 1004 22 0021 LD 1102 23 0022 AND 1103 24 0023 AND 1003 25 0024 AND 1004 26 0025 OUT 20300 27 0026 OUT 20301 28 0027 LD 00010 29 0028 OR 01005 30 0029 OUT 01001 31 0030 LD 00011 32 0031 OUT 01006 33 0032 LD 00100 34 0033 OUT 1007 35 0034 LD 1006 36 0035 AND 1007 37 0036 OR 01101 38 0037 AND 20010 39 0038 AND 1001 40 0039 OUT 1100 41 0040 LD 00101

52

NO ADDRESS OPERAND 42 0041 OUT 1101 43 0042 LD 0007 44 0043 0R 20500 45 004 AND NOT TIM 00 46 0045 AND 1001 47 0046 OUT 20500 48 0047 OUT TIM 00 #10 49 0048 LD 20500 50 0049 OUT 1000 51 0050 LD 0002 52 0051 OR 102 53 0052 AND 1001 54 0053 OUT 20501 55 0054 LD 20501 56 0055 OUT 1104 57 0056 LD 1000 58 0057 OR 20501 59 0058 AND NOT TIM 01 60 0059 OUT 1105 61 0060 LD 20501 62 0061 TIM 01 #20 63 0062 LD 1104 64 0063 TIM 02 #5 65 0064 LD TIM 02 66 0065 AND 1104 67 0066 OUT 1106

53

9.1. Assignment List Of Inputs

Table No.9.1.1.Assignment list of inputs

Name of system : OMRON CPM1A-40CDR Extension :20EDR1

IR000 IR001 IR002

00 Speed trip input from converter

00 Main air flow

00 Ignition push button

01 01 Primary and main air flow bypass

01 Trouble reset push button(NO)

02 Flame OK 02 Total bypass switch

02 Speed reset push button

03 Main Air Pressure 03 Speed on switch

04 LURO motor contact from MMC

04

05 Primary air motor status 05

06 Boiler level 06

07 07

08 Primary air pressure 08

09 Main air pressure 09

10 Sub inter lock bypass switch

10

11 Primary air flow 11

12 12

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9.2. Assignment List Of Outputs

Table No.9.2. Assignment list of outputs

Name of system :OMRON CPM1A-40CDR

IR 010 IR011

00 Ignition on 00 Sulphur pump interlock

01 Sub interlock ready for operation

01 Primary and main air flow bypass

02 Speed low 02 MMC contacts

03 Primary air pressure 03 Steam drum level

04 Main air pressure 04 Sub interlock + flame

05 Sub interlock bypass 05 Gas solenoid valve

06 Primary air flow 06 Kerosene solenoid valve

07 Main air flow 07 Trouble

08 08

55

CHAPTER 10

LADDER INSTRUCTIONS

This line is the line branching instructions. Throughout this instruction line consists a

combination of logic that states when and how the existing instruction.

Fig No.10.1.PLC Ladder Diagram Example

The logic combination of ladder diagram as following:

A. Instruction LOAD (LD) and LOAD NOT (LD NOT) : The first condition that starts any

logic block in the ladder diagram associated with LOAD instruction (LD) or LOAD NOT. (LD

NOT). Each of these instructions requires one line of mnemonics.

B.Instruction (AND) and AND NOT : If two or more conditions that are connected in series on

56

the same instruction line, then the first condition using LD or LD instruction and the remainder

NOT use the instructions AND or AND NOT. AND instruction can be imagined to produce ON if

both conditions are linked with this instruction in all ON conditions, if anyone in the OFF state, let

alone both OFF, the instruction will always result AND OFF too.

C. Instruction OR and OR NOT : If two or more conditions connected in parallel, meaning in a

different line of instructions and then joined again in the same instruction line, then the first

condition associated with LD or LD instruction and the rest is NOT related to the instructions OR

orA OR NOT. In this case imaginable OR instruction will always result in ON execution

condition when any one of two or more conditions connected with this instruction in the ON

condition.

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10.1. Ladder Diagram

58

59

60

Fig No: 10.1.1. Ladder diagram

61

CHAPTER 11

SCREEN SHOTS

Fig No.11.1.Screen shots

62

CHAPTER 12

ADVANTAGES AND DISADVANTAGES

12.1. Advantages

Accurate

We can know the status of inputs and outputs.

Takes up less floor space than a relay wired system

12.2. Disadvantages

Large complicated systems

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CHAPTER 13

APPLICATION

The burner management system focuses on service conditions and safety measures in the

industry.

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CHAPTER 14

CONCLUSION

The programmable logic control (PLC) which was designed in early 1970’s can be

classified as a state member of the computer family. It is a microprocessor based system which

was evolved from the need of control system that can be easily reprogrammed and can control a

large number of operations simultaneously with high grade of synchronism.

The introduction of PLC resulted in a reduction of large machineries devices and human

efforts. It can simply by design as a small modular programmable controller designed for both

relay replacement and complex mid size application. A unique modular bus structure is used as

the foundation for this convenient architecture.

At present the plant is working under the control of an old model PLC family (OMRON

SYSMAC CQM1). Our projects main aim was the up gradation of the existing PLC logic. For this

purpose we studied the old relay logic and the existing PLC logic and upgraded the PLC logic into

newer faster model of the OMRONPLC family (OMRON SYSMAC CPM1A).

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CHAPTER 15

REFERENCES

CPM1A Programmable Controllers – Operation & Programming Manual

Curtis D Johnson; Process Control Instrumentation Technology.

Garry Daning; Introduction to PLC (Second Edition)

www.omron.com

www.wikipedia.org