Study on the N 2O formation under low temperature condition in pulverized biomass combustion

Abstract

The purpose of this study is to clarify the fundamental and general features of N 2O formation during the combustion of pulverized biomass under low temperature. First, the effect of various important factors, i.e., combustion temperature, volatilization process (i.e., either slow or rapid dispersion), and nitrogen content in biomass on N 2O formation were investigated by theoretical analysis. The analysis of the effect of combustion temperature on the formation of nitrous oxide showed that N 2O emission level increases with the decrease in combustion temperature, and both N 2O and NO levels are strongly dependent on the combustion temperature. In other words, there is a trade-off relationship between the formation of NO and that of N 2O. The analysis of the effect of the slow/rapid volatilization process on the formation of nitrous oxide showed that the conversion ratio of biomass-N to N 2O increases with the decrease in the dispersion of volatile matter per unit time; it means that biomass-N is effectively converted to N 2O during slow volatilization. Further, the gasification reactions between CO 2, O 2, and C occur simultaneously on the surface of biomass particles during combustion. With respect to the effect of nitrogen content in biomass, the N 2O emission level increases with the increase in N-content of the biomass, while the NO emission level remains constant during low-temperature combustion. © 2012 by JSME.