Low NOx coal dust combustion method and device based on underfire air and overfire air

Abstract

The invention relates to a combustion improvement technology of an industrial fire coal boiler, aiming to provide a low NOx coal dust combustion method and device based on underfire air and overfire air. The method comprises: injecting parts of two-strand air required for combustion into a hearth from a boiler bottom ash hopper; strongly mixing with aslant downward injected fuel jet flow; fully utilizing the space of the bottom ash hopper to prolong smoke dwell time; burning fuel in a low-temperature oxidation zone; preventing volatile components from converting to nitric oxide; upwards and aslant injecting upper-layer fuel to form a reducing zone, so as to reduce generated nitric oxide into N2; and lowering nitric oxide emission amount. The invention also provides a boiler device for realizing the method. Under the condition that the original combustion condition is not influenced essentially, the invention effectively lowers the emission of nitric oxide and is easy to reform the existing boiler.

Description

technical field [0001] The invention relates to the combustion improvement technology of coal-fired industrial boilers, in particular to a low-NOx pulverized coal combustion method based on downfire wind and overfire air, and a device for realizing the method. Background technique [0002] Nitrogen oxide NO x (NO, NO 2 , N 2 O) is one of the main sources of air pollution. NO can destroy human hemoglobin and cause hypoxia, and also has carcinogenic effects. It reacts with ozone in the stratosphere to destroy the ozone layer, and can also be slowly oxidized by oxygen to NO 2 ; NO, NO 2 It is an acidic pollutant. In addition to causing acid rain and acid fog, it can also produce photochemical smog that is more harmful to humans and the environment with hydrocarbons in the near-earth atmosphere under the action of light. Combustion of fossil fuels is one of the important sources of nitrogen oxides. 70% of my country's energy structure is coal, and the combustion of coal wi...

AI Technical Summary

Problems solved by technology

Although SCR technology is mature and its denitrification efficiency can reach more than 90%, its disadvantages are that it occupies a large area, the system is complex, the initial investment is large, the operating cost is too high, and there is the problem of ammonia escape, which is not suitable for China's national conditions.

Although SNCR technology has low initial investment and simple process, its biggest defect is that the denitrification rate is only 30% to 50%, and it has the same problem as SCR technology that ammonia escapes and causes secondary pollution.

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