Oxidation mechanism of ammonia-N/coal-N during ammonia-coal co-combustion

Abstract

Ammonia-coal co-combustion is a feasible approach to reduce CO2 emissions during thermal power generation, it is necessary to study NO formation mechanism in ammonia-coal co-firing to realize low-carbon and low-nitrogen combustion. The experimental results showed that temperature and ammonia ratio have a significant effect on the NO formation. Under the same ammonia blending amount, the NO production increased first and then decreased with temperature increasing. Theoretical calculations revealed that the formation of NH in NH3→NH→NO is one of the factors restricting ammonia combustion. NH oxidation on the char surface first occurred in the NH/coal/O2 combustion system, and realized the conversion of N to NO, HNO and NO2 through different reaction paths. Combined with the experimental and theoretical calculation results, it was concluded that the reduction of NO by ammonia/char is enhanced at high temperature (>1300 °C), which reduces the conversion of ammonia-N/coal-N to NO.