FORMATION OF N2O IN A CIRCULATING FLUIDIZED-BED COMBUSTOR

Formation of N2O was studied in a circulating fluidized bed boiler by means of injection of CH3CN, NH3, or NO to various locations in the co mbustion chamber. The resulting changes in the emissions of NO and N2O were registered and the formation of N2O was estimated by means of th e measured reduction (from similar experiments with injection of N2O t o the combustion chamber). This was done while burning fuels with high as well as low volatile content: wood chips, bituminous coal and meta llurgical coke. The results show that homogeneous gas-phase reactions are important for the formation of N2O despite the high particle loadi ng in the combustion chamber. Cyanides show a higher tendency to form N2O than ammonia. The concentration of NO and char are also important factors contributing to the formation of N2O.