Schematic operation of the coal based power plant is shown in the figures. Various steps involved in a coal based power plant are given below.
- The pump pressurizes treated water from condenser pressure to the boiler operating pressure.
- In boiler, the water is first heated to its boiling temperature and then, converts to vapor at that temperature, and finally, it is superheated to the required temperature.
- The superheated steam expands from boiler pressure to the condenser pressure in stream turbine.
- The condenser condenses the low pressure steam and water mixture coming from turbine.
- Make up water is added to the condensate and then, the water is again pumped back to the boiler.
This entire cycle, starting from the pumping of the feed water to the condensation of steam and water mixture is called Rankine cycle.
Efficiency of the subcritical Rankine cycle is about 35 %. total energy extracted from this cycle is the area between the solid lines. Total energy supplied to the cycle is area enclosed by solid lines plus condenser duty i.e. area enclosed by two solid lines and two dashed lines.