Nitrous oxide formation and emission in selective non-catalytic reduction process

Abstract

Pulverized coal-fired boilers are not nitrous oxide sources because of high temperature combustion. But selective non-catalytic reduction may produce N2O by NO reduction reactions. Chemical kinetics calculation and experimental research were used to find out the mechanism between N2O and N-agent species, N-agent/NO nitrogen stoichiometric ratio (NSR), reaction temperature, reaction time, etc. The results show that N2O emission decreases with increasing reaction temperature and NSR decreases when reaction time is enough. N2O concentration first increases then decreases as SNCR reactions keep on occuring. Ammonia SNCR tests indicated that N2O emission was 0–7 μmol/mol. About 8.7% of NO was transformed to N2O, and N2O emission was 27.8 μmol/mol at urea-SNCR test. Urea-SNCR is likely to bring N2O emission problem.