Effect of Volatile-Char Interaction on Nitrogen Oxide Emission during Combustion of Blended Coal

Abstract

Utilization of blended coal has been a great issue due to the increasing off-specification coals received in power plants, while the reduction of nitrogen oxide is also attracting extensive attention in China. This study deals with the effect of volatile-char interaction on nitrogen oxide emission during combustion of blended coal using a specially designed tubular multilayer reactor to achieve the separate combustion of volatile and char in a rapid succession. The volatile-char interaction can promote NO reduction at low temperature, while it could give rise to more N2O. The temperature shows a nonmonotonic influence on the conversion of fuel nitrogen. The conversion of volatile nitrogen to NO of blended coal has slight relevance to blending ratio and oxygen content, while the case for char N is significantly different. High oxygen content can promote the transformation from NO to N2O on char surfaces. The interaction between component coals mainly occurs on char during combustion of blended coals. The present study provides insight into the possible interactions on nitrogen oxide release and further NOx reduction in blended coal-fired power plants.