Study On Optimization Of Low Nitrogen Combustion And Ammonia Injection Uniformity For A 660 MW Coal-fired Unit

Nitrogen oxides(NOx)is currently one of the major sources of atmospheric pollution,is a by-product of coal combustion,and is also a major pollutant discharged into the atmosphere with combustion fumes in coal-fired power plants,which can cause significant harm to the environment.influences.This paper takes the #3 unit of a 660 MW coal-fired unit in Jiangxi Province as the research object.The main nitrogen oxide control technology of this unit is to use low-nitrogen combustion technology and selective catalytic reduction(SCR)flue gas denitrification technology to denitrify,but The effect is also easily affected by factors such as coal quality,flue gas temperature,smoke flow field,and uneven mixing of ammonia and nitrogen.In order to further reduce the NOx concentration,this paper analyzes the existing flue gas denitration technology of the unit to meet the lower emission requirements in the future.This paper first describes the formation mechanism and hazards of nitrogen oxides(NOx),introduces the principles and advantages and disadvantages of various nitrogen oxides control technologies at present,and the selection of domestic coal-fired units in the denitrification process.In the primary control of nitrogen oxides,this article focuses on low-NOx combustion technologies,while in secondary control technologies,the focus is on selective catalytic reduction(SCR)and non-selective catalytic reduction of flue gas denitration technologies(SNCR).)Make a detailed introduction.Second,taking the #3 unit of a 660 MW coal-fired unit of a company in Jiangxi Province as the research object,the combustion of the NOx source is optimized.According to the laboratory analysis results of the coal quality and the actual operating conditions of the power plant,a total of eight different coal blending schemes have been designed.This scheme basically covers the power plant when the coal quality changes.The main mode of operation.The test results show that when low-grade coal(represented by Fengcheng Tianyuan)and out-of-provincial coal(represented by Shanxi coal)are burned in the province,the level of NOx generatedby the boiler is the lowest.In terms of the economic benefits of the power plant,this kind of coal blending method is also most beneficial to the power plant.Thirdly,according to the NOx distribution status of the SCR inlet and outlet in the hot state of the unit,the ammonia injection amount in each area of the SCR inlet can be precisely controlled,and the NOx distribution at the outlet can be improved,and the escape of ammonia can be reduced.It is of great significance to guide the plant to optimize ammonia injection.From the optimized data,it can be seen that the NOx concentration distribution at the SCR outlets on the A and B sides has been significantly improved by optimizing the ammonia injection valve three times.The relative standard deviation of the NOx at the A side decreased from 23.1% before optimization to 11.5%.On the B side,it fell from 22.7% to 10.8%.From the adjusted results,it can be seen that the original uneven distribution has been fundamentally improved and the overall NOx distribution has been relatively uniform.At the same time,the A side has been measured through the ammonia slip of the SCR system before and after the optimization on the A and B sides.From the 3.6 ppm before optimization to the optimized 1.4 ppm,the B side was reduced from the pre-optimization of 4.2 ppm to the optimized 1.3 ppm,and after optimization was all below the level of 3 ppm for performance assurance.