Page 294 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

4 It requires less space as compared to the hydroelectric power station.
5 The cost of generation is lesser than that of the diesel power station.

Fig 1

Disadvantages
1 It pollutes the atmosphere due to the production of large amount of smoke and fumes.
2 It is costlier in running cost as compared to hydroelectric plant.

Thermal power plant
The schematic arrangement of a modern steam power station is shown in Figure. The whole arrangement can
be divided into the following stages for the sake of simplicity

1 Coal and ash handling arrangement
2 Steam generating plant
3 Steam turbine
4 Alternator

5 Feed water
6 Cooling arrangement
1 Coal and ash handling arrangement
The coal is transported to the power station by road or rail and is stored in the coal storage plant. From the coal
storage plant, coal is delivered to the coal handling plant where it is pulverized (i.e., crushed into small pieces) in
order to increase its surface exposure, thus promoting rapid combustion without using large quantity of excess
air. The pulverised coal is fed to the boiler by belt conveyors. The coal is burnt in the boiler and the ash produced
after the complete combustion of coal is removed to the ash handling plant and then delivered to the ash storage
plant for disposal. The removal of the ash from the boiler furnace is necessary for proper burning of coal.
2 Steam generating plant
The steam generating plant consists of a boiler for the production of steam and other auxiliary equipment for the
utilisation of flue gases.
i Boiler:The heat of combustion of coal in the boiler is utilised to convert water into steam at high temperature
and pressure. The flue gases from the boiler make their journey through super heater, economiser, air pre-
heater and are finally exhausted to atmosphere through the chimney.

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CITS : Power - Electrician & Wireman - Lesson 106-116