Introduction and some facts about large thermal power station for efficient operation.
Boiler is used for steam generation.
Ball Mill or Bowl mills are used for pulverisation of coal in powder form for efficient firing in boiler.
Raw Coal Feeders are used to supply coal to ball mills in controlled quantity.
PA Fan is used to transport and preheat pulverised coal to burners.
ID Fan is used to exhaust flue gases to chimney and create vacuum in Furnace.
Electrostatic Precipitators are used to separate ash particles from flue gases to control pollution. Here collecting electrode emitting electrode and rapping mechanism used.
FD Fan used to provide air to boiler for help in firing.
Steam produced in boiler is further superheated in Super heaters. There are lot super heaters such as platen, pendent, convection and final super heaters.
Boiler drum used for separation of steam from water and storage. Nowadays drum less once through boiler also used which operates at super critical temperature and Pressure.
Boiler circulation pump used for forced circulation of water in water wall because at high pressure natural circulation is not possible.
Soot Blowers used to remove soot from water wall, Super heater, Re heaters and Air Heaters by injecting steam into heating surfaces.
Ash slurry pumps are used to flush ash with water.
Boiler Feed Pump used to provide water to boiler Drum.
Deaerator used to separate dissolved air from Feed water.
In Turbine heat energy of steam is converted into mechanical energy.
ESV which is called emergency stop valve used to stop supply of steam to turbine when unit trips.
Re heaters used to reheat steam exhausted from HP turbine. After reheating up to 535 degree centigrade same steam is utilised in Intermediate Pressure Turbine.
Barring gear or shaft turning gear is used to rotate turbine rotor at 3.15 rpm when turbine is not running to check bending of rotor due to its own weight.
LP Heaters and HP Heaters are used to heat condensate and feed water supplied to boiler to increase efficiency by steam bled from turbine extraction.
Economiser is used to heat feed water by flue gages to increase efficiency. Heat of waste flue gas is utilised here.
Air Heaters uses heat of waste flue gases to preheat primary and secondary air. There are two types of air heaters tubular and rotary.
Condenser used to condense steam exhausted from turbine.
Condensate Pump are used to supply water to De aerator from condenser Hot well.
CW Pump used to cool steam exhausted from turbine into condensers.
Raw Water is circulated by cw pump into condenser tube hence leakage from condenser tubes must be checked to avoid mixing of raw water into Hot well.
Turbo generator converts mechanical energy into electrical energy.
H2 Gas used in generators used for cooling of generators.
Seal Oil system used to seal hydrogen gas from escape from generator.
Stator Water Cooling system provides demineralised water into hollow stator conductor of generator for its cooling.
Generating Transformer step up voltage for transmission.
Water Treatment Plant is used to produce demineralised water for steam generation. Cation anion and degasifier’s tower used to separate mineral and gases from water.PAC or alum used to separate mud and silica from water. Here minerals removed from water and ph value is maintained near 7 and silica value must less them 0.02 ppm
Coal Handling Plant supplies Coal to Boiler. Merry go round system or wagon tippler used to unload coal into hoppers. Coal is crushed in crusher to crush it in 25mm size. Magnetic separators used to separate metallic particles from coal.
ABCB, SF6, OCB, MOCB and VCB are circuit breakers used to make or break electricity contact at load.
Isolators are used to make or break contact at no loads.
ABT is availability based tariff system to maintain grid discipline.
Purging is done to clean furnace from combustible gases by running ID Fan and FD Fan at least 30% load for 5 minutes to avoid furnace explosion.
Furnace explosion may be checked by timely purging and adjusting firing properly using right quantity primary and secondary air and timely oil support and avoiding leakage of fuel oil in boiler. Furnace must be purged properly again if flame is not established during light up of boiler.
Flame scanners used to sense flame in boiler to detect flame failure to avoid boiler furnace explosion.
FSSS is furnace safeguards supervisory system to safeguard boiler.
Clinker formation which caused by more ash content having low fusion temperature and mineral in poor quality coal may be checked by proper poking and using more water for flushing and use of clinker grinder and regular soot blowing. Over firing which is also cause of clinker formation may be avoided by proper primary and secondary air ratio.
Acoustic Instruments used to detect early boiler tube leakage to avoid secondary damage to pressure parts, Refractory and structures of Boiler. Boiler must be immediately shut down in case of Boiler tube Leakage.
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