Wide-load denitration and stable combustion system and method for assisting coal-fired unit

Abstract

The invention discloses a wide-load denitration and stable combustion system and method for assisting a coal-fired unit. The system involves a hot water recirculation pipeline, a boiler water feedingvalve and an economizer water bypass pipeline, wherein the economizer water bypass pipeline is arranged in front of the boiler water feeding valve and on an economizer water outlet pipeline; the economizer water bypass pipeline is provided with a valve, and the economizer water bypass pipeline is additionally arranged on the position, in front of the boiler water feeding valve, of a water feedingpipeline. Hot water recirculation is achieved through a boiler water circulating pump, and the boiler water feeding valve is used for adjusting the boiler water feeding flow to increase the pressure difference, so that flow of the economizer water bypass is increased; the water inlet amount of an economizer is reduced through the economizer water bypass pipeline, and meanwhile, high-temperature boiler water is injected into the water feeding pipeline through the boiler water circulating pump, so that the inlet water temperature of the economizer is increased, the heat exchange amount of the economizer is reduced, and the SCR inlet flue gas temperature is increased; and the water amount of an economizer water feeding bypass is reasonably adjusted, so that it is guaranteed that economizer water feeding is achieved, boiling is avoided, and normal operation of denitration under the low load is guaranteed while safe operation is achieved.

Description

technical field [0001] The invention belongs to the field of technical transformation of coal-fired units, and in particular relates to a wide-load denitrification and stable combustion system and method for assisting coal-fired units. Background technique [0002] At present, the working temperature of the denitrification devices of most coal-fired power units is 300-420°C. When the unit is in deep peak regulation, as the boiler load decreases, the flue gas temperature at the inlet of the denitrification device will drop below 300°C. Long-term operation at low and operating temperatures will cause the denitrification catalyst to lose its activity, increase the amount of ammonia used, and even cause nitrogen oxidation The discharge of pollutants exceeds the standard, and the peak regulation of the unit is suspended. In the deep peak-shaving renovation project of the power plant, most of the focus is on improving the low-load stable combustion capability of the boiler, ignor...

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Problems solved by technology

When the unit is in deep peak regulation, as the boiler load decreases, the flue gas temperature at the inlet of the denitrification device will drop below 300°C. Long-term operation at low and operating temperatures will cause the denitrification catalyst to lose its activity, increase the amount of ammonia used, and even cause nitrogen oxidation The discharge of pollutants exceeds the standard, and the peak regulation of the unit is suspended

In the deep peak-shaving renovation project of the power plant, most of the focus is on improving the low-load stable combustion capability of the boiler, ignoring the low temperature of the flue gas at the denitrification inlet when the unit is low-load, resulting in increased pressure on the environmental protection of flue gas emissions, deterioration of the working environment of the denitrification device, and catalysts. Negative effects of impaired lifespan

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