Overall Efficiency and Factors Governing Selection of Site Thermal Power Plant
Q. Explain why the overall efficiency of thermal power station is low. Suggest any four remedies for improvement.
|
Stages |
Heat
Losses |
|
To dry flue gases To moisture in gases To ash and unburnt carbon To radiation and leakage Unknown losses Heat rejected to the condenser Alternator losses |
5% 5% in boiler 1% 2.5% 2.5% 54% 1% |
|
|
Total 71% |
Remedies for improving overall efficiency :
- The steam turbine is operated at high temperature and high pressure.
- The condenser is operated at low pressure.
- The steam is reheated between turbine stages.
- Bleeding of turbine is done to improve the thermal efficiency.
The overall efficiency can be improved up to 40% with above methods.
Q. State any six factors governing selection of a site for thermal station and explain each in brief.
Following points should be considered at the time of deciding location of the thermal power station :
- The cost of land should not be high, it should be reasonable. [The cost of land will be high in city area as compared with rural area].
- The land selected be such that it should not be required to acquire private land, if at all required it should be minimum.
- A large quantity of water must be available. Because a thermal plant needs nearly 560 x 103kg of water per tonne of coal used in the boiler, for condensers etc. Hence, the site should be near a river, dam or canal. Otherwise cooling towers are required, increasing the cost of the plant and also some other source of water for make-up of water lost in evaporation.
- Fuel used in the plant should be cheap and available in nearby mines or there should be ample facilities available for the transportation of fuel to the site.
- The site should be such as to provide good and firm foundation to the building and the plant.
- The land should not be rocky, otherwise it will need blasting for foundation etc., at the same time it should not be marshy so as to be required for pile foundations.