Study on Co-firing characteristics of NH3 and coal in the main burning zone of the coal staged combustion

Abstract

The mathematical models including NH3 and pulverized coal were established, and the co-combustion characteristics of NH3/pulverized coal and NOx formation process in the main combustion zone (air consumption coefficient 0.9) of coal staged combustion are studied. The gas temperature distributions and NOx generation characteristics under different ammonia/pulverized coal ratios are investigated. The results show that the ammonia combustion and the NOx production is greatly enhanced by coal combustion when the ammonia and pulverized coal are mixed. For pure ammonia combustion, due to difficult ignition and lower burning rate in the lower gas temperature environment, the NO concentration formed in the furnace and at the outlet are very low; When the proportion of NH3 is 20%, the NOx concentration at the furnace outlet is the highest; when the ammonia gas ratio is 40%, NO at the outlet is lower than that of pure pulverized coal. In addition to a large amount of NO, there are also a large amount of NO2 and N2O in the high temperature region when ammonia and pulverized coal are mixed.