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THERMAL POWER
PLANT
INTRODUCTION : THERMAL POWER PLANTS CONVERT THE HEAT ENERGY OF COAL INTO ELECTRICAL ENERGY. COAL IS BURNT IN A BOILER WHICH CONVERTS WATER INTO STEAM. THE EXPANSION OF STEAM IN TURBINE PRODUCES MECHANICAL POWER WHICH DRIVES THE ALTERNATOR.TOACHIEVE EFFICIENT CONVERSION OF HEAT ENERGY INTO ELECTRIC ENERGY A VARIETY OF EQUIPMENT ARE NEEDED.
SELECTION OF SITE FOR STEAM POWER PLANTS : NEARNESS TO THE LOAD CENTRE
SUPPLY OF WATER
AVAILABILITY OF COAL
LAND REQUIREMENT
TYPE OF LAND
TRANSPORTION FACILITIES
LABOUR SUPPLIES
ASH DISPOSAL
DISTANCE FROM POPULATED AREA
THE MAIN AND AUXILIARY EQUIPMENT IN A THERMAL PLANT ARE : 1. COAL STORAGE 9. COOLING TOWER 2. COAL HANDLING PLANT 10. FEED WATER 3. PULVERISING PLANT 11. ECONOMISER 4. DRAFT FANS 12. SUPERHEATER 5. BOILER 13. AIR PREHEATER 6. ASH HANDLING PLANT 14. ALTERNATOR 7. TURBINE 15. EXCITER 8. CONDENSER 16. TRANSFORMER
1.COAL STORAGE : COAL CAN BE UNLOAD FROM TRAINS AND TRUCKS. AFTER UNLOADING WE SHOULD STORE THE COAL.
2. COAL HANDLING PLANT : THE FUNCTION OF COAL HANDLING PLANT IS AUTOMATIC FEEDING OF COAL TO BOILER FURNANCE. A GRATE AT THE BOTTOM OF THE FURNANCE HOLDS THE FUEL BED. COAL IS WEIGHED AND LED TO HOPPER THROUGH A CONVEYOR MECHANISM.
3. PULVERISING PLANT : PULVERISATION IS A MEANS OF EXPOSING A LARGE SURFACE AREA TO THE ACTION OF OXYGEN AND CONSEQUENTLY HELPING THE COMBUSTION.(RATE OF COMBUSTION).
4. DRAFT SYSTEM : THE COMBUSTION IN THE BOILER REQUIRES SUPPLY OF SUFFICIENT
QUANTITY OF AIR AND REMOVAL OF EXHAUST GASES.
THE CIRCULATION OF AIR IS CAUSED BY A DIFFERENCE IN PRESSURE , KNOWN AS DRAFT.
NATURAL DRAFT _ CHIMNEY .
MECHANICAL DRAFT _ FORCED OR INDUCE DRAFT.(REDUCING THE PRESSURE INSIDE THE BOILER TO LESS THAN ATMOSPHERIC).
5. BOILER : A BOILER IS A CLOSED VESSEL IN WHICH WATER, UNDER PRESSURE, IS CONVERTED INTO STEAM.THERE ARE TWO TYPES OF BOILER:-
(a) FIRE TUBE BOILER
(b) WATER TUBE BOILER
6. SUPERHEATER : REMOVE THE MOISTURE OF STEAM.
7. STEAM TURBINE : A STEAM TURBINE CONVERTS HEAT ENERY OF STEAM INTO MECHANICAL ENERGY AND DRIVES THE GENERATOR.
8. ASH HANDLING PLANT : COAL CONTAINS A CONSIDERABLE OF ASH. ( USE IN CEMENT FACTORY).
9. CONDENSER : THE CONDENSER DOES THE JOB OF CONDENSING THE STEAM EXHAUSTED FROM TURBINE. THE EXHAUST STEAM IS CONDENSED AND USED AS FEED WATER FOR BOILER.
10. COOLING TOWER : A CONDENSER NEEDS HUGE QUANTITY OF WATER TO CONDENSE STEAM. SUCH LARGE REQUIREMENTS OF COOLING WATER CAN BE MET IF THE PLANT IS SITUATED BY THE SIDE OF A BIG RIVER. WATER IS LED INTO THE PLANT BY MEANS OF CIRCULATING WATER PUMPS AND AFTER PASSING THROUGH CONDENSER , IS DISCHARGE BACK INTO RIVER.
11. FEED WATER HEATER : THE STEAM COMING OUT OF THE TURBINE IS CONDENSED AND CONDENSED IS FED BACK TO THE BOILER AS FEED WATER.
12. ECONOMISER : FLUE GASES COMING OUT OF THE BOILERS CARRY LOT OF HEAT. AN ECONOMISER EXTRACTS A PART OF THIS FROM THE FLUE GASES AND USES IT FOR HEATING FEED WATER.
13. AIR-PREHEATER : AFTER THE FLUE GASES LEAVE ECONOMISER, SOME FURTHER HEAT CAN BE EXTRACTED FROM THEM AND USED TO HEAT THE INCOMING AIR FOR COMBUSTION.
14. TRANSFORMER
MERITS : 1. FUEL USED IS CHEAPER.
2. LESS SPACE IS REQUIRED IN COMPARISON WITH THAT FOR HYDROELECTRIC PLANTS.
3. CHEAPER IN INITIAL COST.
4. SUCH PLANTS CAN BE INSTALLED AT ANY PLACE IRRESPECTIVE OF THE EXISTENCE OF FUELS.
5. SUCH PLANTS CAN BE LOCATED NEAR THE LOAD CENTERS.
6. ABLE TO RESPOND TO RAPIDLY CHANGIMG LOADS WITHOUT DIFFICULTY.
7. STEAM ENGINES AND TURBINES CAN WORK UNDER 25% OF OVERLOAD CONTINUOUSLY.
DEMERITS:
1. HIGH MAINTENANCE AND OPERATING COSTS.
2. POLLUTION OF ATMOSPHERE DUE TO FUMES AND RESIDUES FROM PULVERISED FUELS.
3. REQUIREMENT OF WATER IN HUGE QUANTITY.
4. HANDLING OF COAL AND DISPOSAL OF ASH IS QUITE DIFFICULT.
5. TROUBLES FROM SMOKE AND HEAT FROM THE PLANT.
6. REQUIRES LONG TIME FOR ERECTION AND PUT INTO ACTION.
7. EFFICIENCY FALLS RAPIDLY BELOW 75% OF FULL LOAD.
THANK YOU
