The economizer is a device employed in steam power plants to improve the efficiency of the steam cycle by preheating the feedwater entering the boiler. The economizer is essentially a heat exchanger that recovers the heat from the flue gases leaving the boiler and uses it to preheat the water before it enters the boiler.
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In a typical steam power plant, the feedwater is first heated by the steam extracted from the turbine, and then it enters the boiler where it is further heated to produce steam. By using an economizer, the feedwater is preheated before it enters the boiler, which reduces the amount of heat that needs to be supplied by the boiler to produce steam. This results in lower fuel consumption, lower emissions, and higher overall efficiency of the power plant.
In addition to improving the efficiency of the steam cycle, an economizer also helps to reduce the flue gas temperature and increase the overall thermal efficiency of the plant. It is an important component of modern steam power plants and is widely used in both fossil fuel and nuclear power plants.
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The basic construction of an economizer involves a large number of closely spaced parallel steel tubes connected by headers of drums. During its operation, the feed water flows through tubes and flue gases flow outside.
So that was all about the function of the economizer in steam power plants.
Also see: Efficiency of Steam Power Plant