Introduction to Thermal Power Plant

INTRODUCTION TO THERMAL POWER PLANT:

The thermal power plant are coal based power plants. It uses coal as a fuel to generate steam from water in its boiler. There is a closed cycle to enable the working fluid (water) to be used again and again. The cycle used in steam power plant is “Rankine Reheat and Regenerative cycle (modified Rankine cycle). The figure shows this cycle and is self explanatory.

Simple power plant steam water cycle 

Rankine Reheat and Regenerative Cycle [2]

On large turbines, it becomes economical to increase the cycle efficiency by using reheat, by returning partially expanded steam, to a reheater, the average temperature at which heat is added, is increased and, by expanding this reheated steam to the remaining stages of the turbine, the exhaust wetness is considerably less than it would otherwise be conversely.

Regenerative heating of the boiler feed water is widely used in modern Power plants; the effect being to increase the average temperature at which heat is added to the cycle, thus improving the cycle efficiency. steam extracted at various stages of turbine and added to feed water according to their pressure stage. [1]


Various circuits used in thermal power plant

Fuel (Coal) Circuit :

Coal Handling Plant -> Conveyor -> Coal Bunker - > Coal feeder -> Pulverizer (Coal Mill) -> Coal pipe -> Furnace (Boiler)

Water Circuit :

Water Treatment Plant - > Condensate storage tank -> Condensser -> Gland cooler -> L.P.Heater  -> Dearretor -> Boiler feed pump (BFP) -> H.P. Heater -> Economiser (Boiler)

Steam Circuit :

Boiler -> H.P.Turbine -> Re-heater (Boiler) -> I.P.Turbine -> L.P.Turbine -> Condenser 

Air circuit:

Primary air (PA) fan ->Air pre heater -> Coal mill -> Boiler

Force drought (FD) fan -> Air Pre Heater -> Wind Box -> Boiler

Flue Gas Circuit :

Furnace -> Platen SH -> Reheate -> Final SH -> LTSH -> Economizer -> APH -> ESP -> ID Fan -> Chimney

For more details about thermal power plant boiler click on link below
Boiler parts and drawing
References :
[1] Power plant familiarization (Vol.-1), N.P.T.I. Document
[2] Thermodynamics by P.K.Nag