Feed water heater of boiler

Abstract

The invention provides a feed water heater of a boiler. The feed water heater allows the temperature of the metal wall of the final-stage coal economizer of the boiler to be higher than the dew point temperature of the flue gas, prevents low temperature corrosion and ensures that the flue gas can enter into the next stage flue gas evolution system. According to the technical scheme of the invention, the feed water heater comprises a boiler barrel and a final-stage coal economizer. The feed water heater of boiler is characterized in that a feed water heating pipe is positioned in the steam space of the boiler barrel; the outlet of the feed water heating pipe leads to the inlet collection box of the final-stage coal economizer; and the water inlet of the feed water heating pipe is externally connected with a main feed water pipe.

Description

technical field [0001] The invention relates to the mechanical structure field of waste heat boilers, in particular to a boiler feed water heater. Background technique [0002] Because the flue gas produced by the waste heat boiler incineration of domestic waste contains a lot of HCl, SO 2 , SO 3 , HF and other harmful substances, it is necessary to prevent low-temperature corrosion of the economizer. When low-temperature corrosion occurs, it is generally located in the last-stage economizer. At this time, the metal wall temperature of the final-stage economizer is lower than the flue gas dew point temperature. The metal wall temperature of the coal burner is related to the exhaust gas temperature and the internal medium temperature. [0003] Existing waste heat boilers have high exhaust gas temperature under rated operating conditions, so the metal wall temperature of the final economizer is still higher than the flue gas dew point temperature; however, when the boile...

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Problems solved by technology

[0003] Existing waste heat boilers have high exhaust gas temperature under rated operating conditions, so the metal wall temperature of the final economizer is still higher than the flue gas dew point temperature; however, when the boiler is started and the boiler is operating at low load, the boiler exhaust gas temperature is usually Lower, so that the metal wall temperature of the final economizer of the boiler is lower than the flue gas dew point temperature, which is more likely to cause low-temperature corrosion, so that the next-level flue gas purification system cannot play its due role

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