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.
Layout of thermal power plant
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.
2. Economizer
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.
5. Condenser
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.