Numerical Analysis of Diffusion Combustion of Coal-Gasified Fuel : Effect of Pressure on NO_x Formation

Abstract

Numerical computations are made of laminar jet diffusion flames taking into account detailed chemical kinetics and multicomponent diffusion and focusing on the effect of pressure and the amounts of hydrocarbon contained in the fuel on the NO_x formation processes and charcteristics. In order to clearly distinguish between thermal NO_x and fuel NO_x originating from N₂ in the air and fuel N, respectively, and to elucidate the effects of interaction between thermal No_x and fuel No_x together with N-containing species, N-containing species originating from N₂ in air and fuel N and their reactions are distinguished in the computations. It was shown that(1)higher pressure results in a decrease in the amount of fuel NO formed and a increase in the amount of thermal NO formed, (2)the tendency of the decrease of the conversion rate of ammonia to fuel NO for high-pressure flames becomes more apparent when the fuel contains greater amounts of methane, (3)the effect of the destruction of thermal NO by N-containing species becomes more apparent for high-pressure flames as thermal NO concentration becomes high.