Medium-temperature coal economizer system and method thereof for recovering smoke afterheat

Abstract

The invention provides a medium-temperature coal economizer system. The medium-temperature coal economizer system comprises at least one smoke-water heat exchange device, a first flue and a second flue, wherein a smoke inlet of the smoke-water heat exchange device and a flue in an inlet of an air preheater are connected through the first flue; a smoke outlet of the smoke-water heat exchange device and a flue in an outlet of the air preheater are connected through the second flue; and the medium-temperature coal economizer system further comprises a heat exchange device for heating inlet air of the air preheater. The medium-temperature coal economizer system, provided by the invention, shunts part smoke in the inlet of the air preheater, heats water in the smoke-water heat exchange device, heats the inlet air of the air preheater through an air-steam / water heat exchange device, can recover the smoke afterheat, can reduce the smoke temperature, can satisfy the requirement of lowering the smoke temperature in the inlet of a low-temperature dust remover, can improve the dust removing efficiency, and can prevent such problems as low-temperature corrosion and blockage at a cold end of the air preheater. The invention further provides a method for recovering the smoke afterheat by adopting the medium-temperature coal economizer system.

Description

technical field [0001] The invention belongs to the field of thermal coal-fired generating sets, and in particular relates to a medium-temperature economizer system applied to a thermal power plant and a method for recovering waste heat from flue gas. Background technique [0002] The flue of the traditional thermal power plant unit before the air preheater is equipped with a high-temperature economizer, which uses the heat of the flue gas of the boiler to heat the feed water, which can absorb the heat of the flue gas to improve the efficiency of the boiler and increase the temperature of the feed water in the water wall. , with the continuous improvement of environmental protection requirements such as energy saving and emission reduction, some thermal power plant units will also configure a 'flue-water' heat exchanger in the follow-up flue of the boiler air preheater, that is, use the flue gas after the boiler air preheater The heat is used to heat condensed water or hot n...

AI Technical Summary

Problems solved by technology

For boilers with normal exhaust gas temperature, if the exhaust gas temperature is further lowered, the average wall temperature of the heat exchange fins on the low temperature side of the air preheater will drop below the design value, which will inevitably lead to condensation of sulfuric acid, corrosion and blockage of the heat exchange surface. The risk has increased sharply, and the gain outweighs the gain, so this technology is no longer used in the newly built units in Germany

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