Monday, November 17, 2014

Coal Based Thermal Power Plant

A coal-fired power station produces electricity, usually for public consumption, by burning coal to boil water, producing steam which drives a steam turbine which turns an electrical generator.
Coal is a relatively cheap fuel with some of the largest deposits in politically stable regions (China, India and the US) thus generally offering a more stable supply than natural gas and oil, the largest deposits of which are located in the more politically volatile Persian Gulf.

Why a Coal-fired power plant?

Coal-fired power plants are a proven, reliable and efficient way to generate electricity, and are critical to meeting power-grid demand. The basic construction of single reheat large steam turbines for coal-fired power plants was established over 30 years ago. This construction, designed originally for operating at conventional steam conditions, has achieved very high standards of reliability and operability through continuing development and feedback of operating experience. The same basic design therefore provides a very sound reference base for high output applications at supercritical operating conditions taking advantage of advanced materials and design refinements. Advanced pulverized-coal-fired power plants are well suited for mid-range power supply and support the grid system to avoid blackouts. Coal's value as a power plant fuel is greatly enhanced by its ability to supply power during peak power demand -- as base power -- and off-peak power demand.

Diagram of a typical coal-fired thermal power station

1. Cooling tower
2. Cooling water pump
3. Transmission line (3-phase)
4. Unit transformer (3-phase)
5. Electric generator (3-phase)
6. Low pressure turbine
7. Boiler feed pump
8. Condenser
9. Intermediate pressure turbine
10. Steam governor valve
11. High pressure turbine
12. Deaerator
13. Feed heater
14. Coal conveyor
15. Coal hopper
16. Pulverized fuel mill
17. Boiler drum
18. Ash hopper
19. Superheater
20. Forced draught fan
21. Reheater
22. Air intake
23. Economizer
24. Air preheater
25. Precipitator
26. Induced draught fan
27. Chimney Stack
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