Thermal power plants, construction and layout
Thermal power plants, also called steam power plant is based on fuel “coal”. In this the heat energy is converted into mechanical energy and then to electrical energy through turbine generator system. The heat energy is obtained by the combustion of coal, through which steam is produced. The discharged steam is exhausted by prime movers and then it is condensed by condenser to be fed into boiler.
The thermal power plant can be sub-divided into following several small units.
1. Fuel handling plant
2. Ash handling plant
3. Boiler unit
4. Feed water plant
5. Cooling water plant
6. Generator unit
7. Turbine unit.
The schematic diagram is shown in fig. below
Various components of thermal power plant layout
1. Super heater
It converts the wet steam from boiler into dried steam at super-heated temperature (steam temp is increased beyond boiling point of water). Thus process improves the overall effinency of thermal plant.
It uses the heat of flue gases coming from boiler to increase the temperature of feed water before it is supplied to boiler.
3. Air peachier
It uses the heat of flue gases to increase the temperature of air used for combustion of coal.
4. Steam turbine
It converts the thermal energy of steam of mechanical energy of turbine.
It condenses the exhaust steam by cold water circulation.
6. Cooling tower
It is used to convert hot water from condenser into cold water to be reused for coaling exhausted steam in condenser.
Function of super heated steam
Super heated steam contains more heat than the saturated steam at same pressure. The additional heat provides more energy to the turbine and so electrical output is more. Superheated steam causes lesser erosion to turbine blades.
The function of super heated is to remove the last traces of moisture from the saturated steam leaving the boiler tube and rises the steam temperature.
Function of pulverized coal
Pulverization means increasing the surface area of coal that helps in combustion.
The advantage of pulverized coal is
1, the rate of combustion can be controlled and changed quickly to meet varying load.
2. The banking losses are reduced.
3. The percentage of excess air required is low.
4. Automatic combustion control can be used
5. Preheated air can be used successfully.
6, a wide variety of even low grade coals can be used.
7. The boiler can be started from cold conditions very rapidly.
8. Even fine wet can be used provided the conveying equipment can carry into palavering mill.
Function of pre located Air:
After the flue gas leave economizer, some further heat can be extracted cooling of flue gasses by 20 degree raises plant efficiency 1%.
Efficiency of thermal power plant
The overall efficiency of the thermal power plant is low. The overall plant efficiency does not exceed 40% and generally it is 30%. The main reason for low efficiency of thermal plants is poor efficiency of the thermodynamic cycle. The efficiency of thermodynamic cycle is about 45%.
Hence these are thermal power plant construction and layout. if you find any incorrect above you must comment below in comment box.