350MW循环流化床锅炉氨煤混燃的NOx排放特性数值模拟研究OA

[Objective]To promote the low-carbon transformation of coal-fired power units,ammonia-coal co-firing technology has become an important research direction for emission reduction in coal-fired power generation.[Methods]Based on computational fluid dynamics(CFD),this study performed numerical simulations of the ammonia-coal co-combustion process and pollutant emission characteristics in a 350 MW circulating fluidized bed(CFB)boiler.First,the ammonia injection position was optimized by comparing the combustion and NOx emission characteristics at three different injection points:the upper secondary air port,lower secondary air port,and coal feeding port.Then,the effects of ammonia blending ratios(0％,10％,15％,and 20％)on furnace combustion and NOx emissions were analyzed.Finally,the influence of the excess air ratio on ammonia-coal co-combustion characteristics was examined.[Results]The results show that:(1)The best ammonia injection position is the coal inlet,and the NOx emission concentration is 12.5％and 9.4％lower than that of the upper and lower secondary air outlets,respectively,and the minimum ammonia escape concentration is 4.5 mg/m3;(2)The optimal blending ratio of ammonia coal is 15％.At this time,the NOx emission is about 3％higher than that of pure coal combustion,the furnace temperature decreases by about 30 K,and the ammonia escape concentration remains at a low level.(3)The optimum excess air coefficient is 1.25,and the co-combustion state of ammonia and coal is the best.[Conclusion]Through numerical simulations of the ammonia-coal co-combustion process and pollutant emissions in a 350 MW supercritical CFB boiler,this study determined the optimal ammonia injection position,blending ratio,and excess air ratio,providing a theoretical reference for the low-carbon retrofit of circulating fluidized bed boilers.