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Thermal power plant

thermal power or steam power plant

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Thermal power plant

  1. 1. Thermal Power Plant Prepared By: Vivek Pathak
  2. 2. INTRODUCTION Talking of a thermal power, a number of major parameters need to be considered. Firstly, selecting a suitable site for a thermal pant is of utmost importance.  The thermal plant consumes huge amount of fuel principally coal.  It is estimated that for every megawatt produced, a plant needs more than 10,000 tons of coal. 
  3. 3. Arrangement must exist to bring the coal from mines and store the coal.  Secondly, in the Thermal power plant layout, there must be provision to dispose of large quantities of ash generated.  It is estimated that for storage of coal, ash disposal building of the plant itself and residential space for workers etc you would need approximately 3 acres of land for every megawatt generated.  Lastly you need huge quantities of water to run the plant. A perennial water source like a river nearby is needed to run a thermal power plant. 
  4. 4. INTRODUCTORY OVERVIEW A thermal power station is a power plant in which the prime mover is steam driven.  Water is heated, turns into steam and spins a steam turbine which drives an electrical generator.  After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated. 
  5. 5.  The greatest variation in the design of thermal power stations is due to the different fuel sources.
  6. 6. Energy Conversion Process in Thermal Power Plants Fuel Chemical Energy Chemical Energy is Converted into Thermal Energy by Combustion In Boiler Thermal Energy Thermal Energy is Converted into Mechanical Energy In Turbine Mechanical Energy Electrical Energy Mechanical Energy is Converted into Electrical Energy In Generator
  7. 7. Energy Conversion . . .     Fuel, Air and water produce steam in the boiler by combustion Steam of high temperature and pressure is expended from high pressure to low pressure in the turbine Thermal energy is converted into kinetic energy and finally mechanical energy This mechanical energy derives the generator to produce electricity
  8. 8. Thermal Power Plant can work in two Manners 1. 2. Production of electricity Production of electricity with production of steam for the use in industry e.g. paper mills, textile mills, sugar mills, refineries
  9. 9. Processing of Power Plant Boiler Water Steam Grid Turbine Fuel Generator Exhaust Steam Waste Gases
  10. 10. Efficiency Efficiency = Heat Equivalent of Electrical output / Heat of Combustion Normally η = 29% Losses: 1. Boiler House Losses: a. To Dry Fuel Gases b. To moisture in gases c. To ash and unburnt carbon d. To radiation and leakage e. Unknown losses TOTAL  5% 5% 1% 2.5% 2.5% 16%
  11. 11. Efficiency . . . Turbine Losses: a. Heat rejection to Condenser 54% 3. Alternator or Generator Loss 1% TOTAL 55% Grand Total 71% So Efficiency = (100% - Losses) = 100% - 71% = 29% 2.
  12. 12. Merits of Thermal Power Plant       Fuel is cheaper* Less space is required The initial cost is less Plant can be located near the load centre Turbine can work at 25% overload continuously A portion of steam can be used in various industries
  13. 13. Demerits of Steam Power Plant       Maintenance and operating costs are high Pollution of atmosphere is one of the major problems Water is required in huge quantity Handling of coal and disposal of ash are difficult tasks It requires long time for installation Efficiency falls quickly below 75%
  14. 14. Site Selection        Availability of Coal (Fuel) Proper arrangement for ash disposal Nature of the land Location from load centre Availability of water Transport facilities Availability of labor
  15. 15. Main Circuits of Thermal Power Plant     Coal and Ash Circuit Air and Gas circuit Feed Water and Steam circuit Cooling Water circuit
  16. 16. Coal and Ash Circuit   Coal from the storage is fed to the boiler through coal handling equipment for the generation of steam. Ash produced due to combustion of coal is removed to ash storage through ashhandling system
  17. 17. Air and Gas Circuit      Air is supplied to the combustion chamber of the boiler either through forced draught or induced draught fan or by using both. The dust from the air is removed before supplying to the combustion chamber. The exhaust gases carrying sufficient quantity of heat and ash are passed through the air-heater. Here the exhaust heat of the gases is given to the air then it is passed through the dust collectors where most of the dust is removed before exhausting the gases to the atmosphere
  18. 18. Feed Water and Steam Circuit      The steam generated in the boiler is fed to the steam prime mover to develop the power The steam coming out of the prime mover is condensed in the condenser and then fed to the boiler with the help of pump The condensate is heated in the feed-heaters using the steam tapped from different points of the turbine The feed water supplied from external source is passed through the purifying plant to reduce to reduce dissolve salts to an acceptable level This purification is necessary to avoid the scaling of the boiler tubes
  19. 19. Cooling Water Circuit   The quantity of cooling water required to condense the steam is considerably high and it is taken from a lake, river or sea . The water is pumped in by means of pumps and the hot water after condensing the steam is cooled before sending back into the pond by means of cooling towers
  20. 20. Major Parts of Steam Power Plant 1. Boilers 3. Turbine 5. Economizer 7. Induced Draft Fan 9. Chimney 11. Ash Handling Plant 13. Alternator 15. Pumps 2. Superheater 4. Condenser 6. Air preheater 8. Forced Draft Fan 10. Coal Handling Plant 12. Cooling Tower 14. Evaporator
  21. 21. 1. Boiler Purpose: To produce steam under pressure Types: 1. Fire Tube Boiler: Hot gases of combustion are inside the tubes and the tubes are surrounded by water 2. Water Tube Boiler: Water is inside the tube and hot gases are outside the tube One of these are used according to the requirements
  22. 22. Fire Tube Boiler
  23. 23. Water Tube Boiler
  24. 24. Superheater Device used to remove the traces of moisture from saturated steam leaving boiler tubes.  It also increase the temperature above saturation temperature Classes: 1. Radiant Superheater: Located in the furnace between the furnace water walls and absorbs heat from the burning fuel through radiation 2. Convection Superheater: Located well back in boiler tube bank. It receives its heat from flue gases through convection. 
  25. 25. Economizer   It absorbs heat from outgoing flue gases and used for raising the temperature of feed water coming from condenser Economizer raises efficiency of boiler by 10 12 % thus 5 – 15 % of fuel consumption is saved
  26. 26. Air Preheater   Air preheater is used to recover heat from flue gases since entire heat can’t be extracted by economizer Boiler Efficiency is increased by 1% if the avg. air temp. is increased by 20 C
  27. 27. Steam Turbines  1. 2. There are two types of steam turbines Impulse type: Steam expands completely in the stationary nozzles, the pressure over the moving blades remains constant. Reaction Type: Steam is expanded both in fixed blades (nozzles) and moving blades.
  28. 28. Coal Handling 1.  2.  Coal shouldn’t be exposed to air It pollutes the air and releases poisonous gases like carbon monoxide The coal from the heaps is moved into the plant by means of long conveyors that are electrically operated There are many different types of conveyors and coal-handling devices like screwing conveyors, bucket elevators, grabbing bucket conveyors etc.
  29. 29. Coal Crusher   Before the coal is sent to the plant it has to be ensured that the coal is of uniform size so it is passed through the crushers Rotary crushers are very commonly used for this purpose as they can provide a continuous flow of coal to the pulverizer
  30. 30. Coal Crusher . . .
  31. 31. Pulverizer    Are used to smash materials into tiny granular. Most commonly used pulverizer is the Boul Mill The arrangement consists of 2 stationary rollers and a power driven baul in which pulverization takes place as the coal passes through the sides of the rollers and the baul
  33. 33. Installed Plant Capacity Of Thermal Power Plant In India
  34. 34. Installed Plant Capacity Of Thermal Power Plant In World
  35. 35. Rank Station Country Location Capacity (MW) Ref 1 Taichung Power Plant Taiwan 24°12′46″N 120°28′52″E 5,500 [23] 2 Tuoketuo Power Station China 40°11′49″N 111°21′52″E 5,400 [24][25][26] 3 Bełchatów Power Station Poland 51°15′59″N 19°19′50″E 5,354 [27][28][29] 4= Guodian Beilun Power Station China 29°56′37″N 121°48′57″E 5,000 [30] 4= Waigaoqiao Power Station China 31°21′21″N 121°35′54″E 5,000 [31][32] 4= Guohoa Taishan Power Station China 21°52′00″N 112°55′22″E 5,000 [33] 4= Jiaxing Power Station (zh) China 30°37′46″N 121°8′49″E 5,000 [34]