Study On Debugging Scheme Of SNCR+SCR Combined Denitration Technology Of 240t/h Pulverized Coal Furnace Flue Gas

With the gradual improvement of environmental protection standards for NO_x emissions,SNCR+SCR is a flue gas denitration process widely used in coal-fired power plants at present.The process has high denitration efficiency,stable operation,NO_x removal rate can reach more than 90%,and no secondary pollution.In this paper,the SNCR+SCR urea injection denitration process of a power plant in Zibo,Shandong Province was taken as the research objective.Through the process height,the optimal ammonia injection amount combination of SNCR under different loads was explored,and its emission effect was verified,and the conclusions were drawn as follows:1.Under low load(220t/h),the optimal ammonia injection volume of the three spray gun modules of SNCR denitration system is 88kg/h,84kg/h and 86kg/h,respectively;Under this condition,after SNCR treatment,the average NO_x emission concentration is 328.31mg/Nm~3,and the average denitration efficiency is 31.46%.After SCR denitration system,the average emission concentration is 84.68mg/Nm~3,the average denitration efficiency is 74.20%,and the average ammonia escape concentration is 0.07mg/m~3,which can reach the standard stably.2.Under the standard load(240t/h),the optimal ammonia injection volume of the three modules of SNCR denitration system is 88 kg/h,86 kg/h and 80 kg/h,respectively;Under this condition,after SNCR treatment,the average NO_x emission concentration is 319.23 mg/Nm~3,and the average denitration efficiency is 36.15%.After SCR denitration system,the average NO_x emission concentration is 83.54mg/Nm~3,the average denitration efficiency is 73.82%,and the average ammonia escape concentration is 0.07mg/m~3,which can reach the standard stably.3.Under overload(260 t/h),the optimal ammonia injection volume of three modules of SNCR denitration system is 76 kg/h,74 kg/h and 86 kg/h,respectively;After SNCR treatment,the average NO_x emission concentration is350.53mg/Nm~3denitration efficiency is 32.20%,after SCR denitration system,the average emission concentration is 88.31mg/Nm~3,the average ammonia escape concentration is 0.03mg/Nm~3,can reach the standard stably.4.Considering NO_x raising requirements,at low load(220 t/h),the denitrification efficiency is 84.77%when the average emission concentration before SCR denitrification system treatment is reduced from 328.31 mg/nm3 to 50 mg/nm3;Under standard load(220 t/h),the denitration efficiency is 84.34%when the average emission concentration before SCR denitration system is reduced from319.23 mg/Nm~3to 50 mg/Nm~3.Under overload(260 t/h),when the average emission concentration before SCR system treatment is reduced from 350.53 mg/Nm~3to 50mg/Nm~3,the denitration efficiency is 85.74%,both of which are lower than the maximum denitration capacity of 90%.The whole denitration system can also achieve ultra-low emission under different loads.