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2 ENGINEERING THERMODYNAMICS

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Econo-

miser

Flue

gases

Steam

turbine Generator

Cooling tower

Pump

Feed water

pump

Boiler

with

Superheater

Coal/Oil

Air from

boiler

Air preheater

Chimney

To atmosphere

Condenser

Fig. 1.1. Layout of a steam power plant.

A part of steam and water is lost while passing through different components and this is

compensated by supplying additional feed water. This feed water should be purified before hand, to

avoid the scaling of the tubes of the boiler.

Cooling Water Circuit. The cooling water supply to the condenser helps in maintaining

a low pressure in it. The water may be taken from a natural source such as river, lake or sea or the

same water may be cooled and circulated over again. In the latter case the cooling arrangement is

made through spray pond or cooling tower.

1.1.2. Components of a modern steam power plant

A modern steam power plant comprises of the following components :

1. Boiler
   (i) Superheater (ii) Reheater
   (iii) Economiser (iv) Air-heater.


2. Steam turbine 3. Generator


3. Condenser 5.Cooling towers


4. Circulating water pump 7. Boiler feed pump


5. Wagon tippler 9. Crusher house


6. Coal mill 11. Induced draught fans


7. Ash precipitators 13. Boiler chimney


8. Forced draught fans 15. Water treatment plant


9. Control room 17. Switch yard.
   Functions of some important parts of a steam power plant :


10. Boiler. Water is converted into wet steam.


11. Superheater. It converts wet steam into superheated steam.


12. Turbine. Steam at high pressure expands in the turbine and drives the generator.