A system for increasing the flue gas temperature at the inlet of denitrification under low load

Abstract

The invention relates to a system for increasing the smoke temperature at a denitration inlet under the low load. The system comprises an economizer in a flue, an air preheater and a selective catalytic reduction (SCR) denitration device. According to the system, the flue before an inlet of the SCR denitration device is separated into an SCR inlet main flue and an SCR inlet bypass flue, motor-driven flue baffles are arranged at the front part of the SCR inlet main flue and the front part of the SCR inlet bypass flue, driving motors are connected with a control host, temperature transmitters connected with the control host are arranged before and behind the flue baffles, a heat storage device is arranged in the bypass flue, electric valves are mounted on a water inlet pipe and a water outlet pipe of the heat storage device, and the control host controls the working states of the flue baffles and the electric valves according to the temperature values collected by the temperature transmitters. With the system, the SCR inlet smoke temperature is kept in a catalyst adaptation temperature range while the overall efficiency of a boiler is unchanged, so that the denitration device can better adapt to the change of the load of the boiler.

Description

technical field [0001] The invention belongs to the technical field of denitrification of coal-fired units in power plants, in particular to a system for increasing the smoke temperature at a denitrification inlet under low load. Background technique [0002] With the country's increasing emphasis on environmental protection, coal-fired boilers need to be equipped with denitrification devices in accordance with relevant national laws and regulations. The optimal reaction temperature of catalyst in SCR denitrification device is 308-420℃, and the flue gas temperature at SCR inlet varies with the change of boiler load. When the inlet flue temperature of the SCR denitrification device is too high, the catalyst channels and micropores will be deformed, resulting in a reduction in the effective channels and area, thereby deactivating the catalyst. When the flue temperature is too low, a side reaction will occur on the catalyst, and the generated (NH4)2SO4 or NH4HSO4 will stick to...

AI Technical Summary

Problems solved by technology

When the flue temperature is too low, a side reaction will occur on the catalyst, and the generated (NH4)2SO4 or NH4HSO4 will stick to the denitrification catalyst and the air preheater, and absorb dust, resulting in a decrease in catalyst activity and blockage of the air preheater. The pressure difference between the reactor and the air preheater increases slowly, which affects the safe and stable operation of the unit

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