Application Of Direct Injection Modification Of Denitrified Urea In Zhangjiakou Power Plant

At present,about half of the world's coal is from China,and about half of the coal is consumed by China every year.In 2016,the SO2 emissions in China were about 11 million tons,and the NOx emissions were close to 14 million tons.The emissions of all kinds of main pollutants rank the highest in the world.The problem of environmental destruction caused by the massive discharge of pollutants has deeply affected people's daily life.For decades,China's economy has developed rapidly.However,it has not paid enough attention to energy conservation and environmental protection,and there is a serious dependence on coal in China.Now 70% of China's electricity needs coal-fired power generation,and this situation will not change essentially in a short time.In the process of coal combustion,a large amount of NOx will be discharged,which will cause serious environmental pollution,causing acid rain,photochemical smog and other environmental problems,which pose a serious threat to the health,vegetation and building of industrial and agricultural production,human and animal.Therefore,all countries in the world set strict standards for the emission of NOx.Now the denitration method has low NOx combustion technology and flue gas denitrification technology.Low NOx combustion technology has some limitations and low efficiency.The technology of flue gas denitrification includes ozone oxidation absorption,activated carbon combined desulphurization and denitrification,electron beam joint desulfurization and denitrification,selective non catalytic reduction(SNCR)and selective catalytic reduction(SCR),among which SCR is the most mature and widely used.There are 8 320 MW coal-fired units in Zhangjiakou power plant.The original denitration system adopts urea pyrolysis SCR process.In order to meet the environmental requirements of ultra-low emission,the Zhangjiakou power plant in 2015 carried out a denitrification super low emission transformation project.The 1~7 furnace increased the direct injection technology in the furnace,and the original pyrolysis furnace system and the electric heater quit operation as the denitration standby system.Furnace No.8 is still using the original pyrolysis furnace system.In order to increase ammonia output of the original denitration system,the power of electric heater increased from 660 KW to 900 KW.By comparing the operation array of January ~2018 January 2017,it is found that the efficiency of denitrification of unit 1~7 is obviously higher than that of unit 8 without modification,and the emission of NOx is obviously lower than that of Unit No.8;in addition,the denitrification capacity of unit 8 is poor and the consumption of urea is large.It shows that the transformation project is effective for energy saving and emission reduction.