Steam Power station efficiency:
The overall efficiency of a steam power station is quite low (about 29%) due mainly to two reasons.Firstly, a huge amount of heat is lost in the condenser and secondly heat losses occur at various stages of the plant.The heat lost in the condenser cannot be avoided. It is because heat energy cannot be converted into mechanical energy without temperature difference. The greater the temperature difference, the greater is the heat energy converted into mechanical energy.This necessitates to keep the steam in the condenser at the lowest temperature.But we know that greater the temperature difference, greater is the amount of heat lost.This explains for the low efficiency of such plants.
(i) Thermal efficiency : The ratio of heat equivalent of mechanical energy transmitted to the turbine shaft to the heat of combustion of coal is known as thermal efficiency of steam power station.
The thermal efficiency of a modern steam power station is about 30%.It means that if 100 calories of heat is supplied by coal combustion, then mechanical energy equivalent of 30 calories will be available at the turbine shaft and rest is lost.It may be important to note that more than 50% of total heat of combustion is lost in the condenser.The other heat losses occur in flue gases, radiation, ash etc..
(ii) Overall efficiency : The ratio of heat equivalent of electrical output to the heat of combustion of coal is known as overall efficiency of steam power station
i.e.
The overall efficiency of a steam power station is about 29%.It may be seen that overall efficiency is less than the thermal efficiency.This is expected since some losses (about 1%) occur in the alternator.The following relation exists among the various efficiencies.
Overall efficiency = Thermal efficiency × Electrical efficiency
The overall efficiency of a steam power station is quite low (about 29%) due mainly to two reasons.Firstly, a huge amount of heat is lost in the condenser and secondly heat losses occur at various stages of the plant.The heat lost in the condenser cannot be avoided. It is because heat energy cannot be converted into mechanical energy without temperature difference. The greater the temperature difference, the greater is the heat energy converted into mechanical energy.This necessitates to keep the steam in the condenser at the lowest temperature.But we know that greater the temperature difference, greater is the amount of heat lost.This explains for the low efficiency of such plants.
(i) Thermal efficiency : The ratio of heat equivalent of mechanical energy transmitted to the turbine shaft to the heat of combustion of coal is known as thermal efficiency of steam power station.
The thermal efficiency of a modern steam power station is about 30%.It means that if 100 calories of heat is supplied by coal combustion, then mechanical energy equivalent of 30 calories will be available at the turbine shaft and rest is lost.It may be important to note that more than 50% of total heat of combustion is lost in the condenser.The other heat losses occur in flue gases, radiation, ash etc..
(ii) Overall efficiency : The ratio of heat equivalent of electrical output to the heat of combustion of coal is known as overall efficiency of steam power station
i.e.
The overall efficiency of a steam power station is about 29%.It may be seen that overall efficiency is less than the thermal efficiency.This is expected since some losses (about 1%) occur in the alternator.The following relation exists among the various efficiencies.
Overall efficiency = Thermal efficiency × Electrical efficiency
Efficiency of Steam power station
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