Thermal power plants

Steam/Thermal power plants

What is steam/thermal power plant?

The power plant which uses heat energy produced by burning of fuel and converts it into electrical energy called as steam or thermal power plant.

Classification of steam power plants

The steam power plants are classified as follows:

     1)    Central power station- The power produced by power plants for sale to various consumers. E.g. household purpose

     2)    Industrial power station- The power produced by power plants for their personal use. E.g. industry 

Site selection for thermal power plants

The following factors should be consider during selection of site for thermal power plant-

1)    Availability of raw material – Thermal power plants uses large amount of coal and oil as fuel so, it is necessary to locate power plant near to coal fields to reduce cost of transportation.

2)    Availability of water- Steam power plants uses large amount of water as working fluid so it is necessary to locate power plant near river, lake, or sea side.

3)    Availability of labour- Large men power is required during construction and working of power plant.

4)    Availability of transport facilities – The power plant should be located where transportation facilities are available for transportation of fuel and heavy machinery. Also for manpower.

5)    Location of load centre – To reduce transmission cost power plant should be located near power plant.

6)    Nature and cost of land – The selected site should not have mineral deposition also cost of land must be reasonable because power plant requires large area. It reduce capital cost of power plant.

7)    Ash disposal facilities – In thermal power plants large amount of ash is produced which is hazardous to human and nature too. Therefore there must be sufficient space for ash disposal.

8)    Future expansion – The selected site should allow expansion of plant in future.

9)    Pollution – Thermal power plants causes pollution therefore they should be located away from populated area.

10)  Away from air fields – The power plant should be located away from densely populated area.

Diagram-

fig.Simple layout of steam/thermal power plant

Essential components and systems of steam power 
plant-

    1)    Steam boiler

    2)    Steam turbine

    3)    Condenser

    4)    Cooling tower

    5)    Coal handling system

    6)    Ash and dust handling system

    7)    Water treatment system

Working of steam power plants-

Steam power plants works on Rankine cycle .Water is feeded to boiler and steam is generated in boiler at high pressure and temperature. 

That steam is supplied to steam turbine and steam turbine rotates and produces mechanical energy. Steam turbine is coupled with alternator which converts mechanical energy to electrical energy.

The exhaust steam of steam turbine is condense in condenser. The condense steam is again feed to boiler. This cycle continues and steam power plants produce electrical energy.

Advantages of steam power plant-

    1)    Space required is less compared to hydroelectric power plant.

    2)    Fuel used is cheaper.

    3)    They can be located near the load centres.

    4)    They can be overloaded upto 20% without difficulty.

Disadvantages of steam power plant-

    1)    Operational and maintenance cost is high.

    2)    Large quantity of water required.

    3)    It causes pollution.

    4)    Problem of ash disposal.