Parametric studies on N 2O formation and destruction mechanisms

Abstract

This paper reports investigations of the influence of some combustion parameters on the formation/destruction of N 2O from coal combustion. The gas phase formation of N 2O was theoretically analysed, and the results were compared with the experimental data obtained. Calculations were performed for adiabatic constant volume combustion on the basis of 108 elementary reactions involving 30 different chemical species. The comparisons with experimental data were made within a temperature range from 800–1100°C, taking into account the effect of various operating parameters, viz. temperature, devolatilisation process, concentration of CH 4, HCN/NH 3 ratio etc. The experimental results were satisfactorily explained by the theoretical modelling. The results show that N 2O formation/destruction is very sensitive to the combustion temperature, as well as to the devolatilisation scheme of the coal. Besides, the concentration of CH 4 and the presence of NH 3 and HCN also have significant roles in the N 2O formation and destruction mechanisms. The results show that the presence of NH 3 helps in the conversion of N 2O to NO, whereas HCN acts as the activating source of N 2O formation. This trend is very much temperature dependent.