Role of carbide slag addition on NO emission characteristics during coal combustion

Abstract

This work presents an experimental study on the NO emission characteristics of coal combustion with carbide slag addition. Combustion experiments were carried out in a fixed-bed reactor to investigate the effects of Ca/S molar ratio, oxygen concentration and reaction temperature on the transformation of fuel nitrogen to NO emission. Further, a pilot test was performed in a 30 kW CFB reactor to study the influence of carbide slag on the NO emission. Experimental results show that using carbide slag and a high Ca/S molar ratio promoted the fuel-N/NO conversion rate. The main contribution to the fuel-N/NO conversion rate increment was the catalytic role of carbide slag in the char-N/NO conversion process. The promotion effect of carbide slag on fuel-N/NO conversion was weakened at a higher temperature and lower O2 concentration. The pilot test results verified that using carbide slag promoted NO emission. Based on the test results, the fuel-N conversion route and the NO formation process during coal combustion with carbide slag addition were presented.