Thermal Power Plant Questions and Answers

1. Draw the overall block diagram of a coal-based thermal power plant.

2. Explain the function of – (i) Economizer, (ii) Superheater and (iii) Reheater in a steam power plant.

(i) Economizer:
An economizer uses the heat of the flue gases to preheat the feed water before it enters the boiler. This reduces fuel consumption and increases boiler efficiency.

(ii) Superheater:
A superheater heats the saturated steam (wet steam) coming from the boiler to a higher temperature above its saturation temperature. It produces dry superheated steam, which improves turbine efficiency and reduces moisture in the turbine.

(iii) Reheater:
A reheater takes partially expanded steam from the turbine and heats it again before sending it to the next stage of the turbine. It increases the efficiency of the plant and reduces moisture content at the turbine exhaust.

3. Why is Pulverization of Coal Done in Thermal Power Plants?

Pulverization means crushing coal into a fine powder before burning it in the boiler.

It is done because:

1. Increases the surface area of coal, allowing it to burn more quickly and completely.
2. Improves combustion efficiency and reduces unburnt carbon.
3. Increases the rate of heat release, producing steam faster.
4. Reduces fuel consumption and improves the overall efficiency of the thermal power plant.