The prediction of NO sub(x) emissions from spray combustion

The study of in-flame chemical processes involving nitrogenous species forms an important part of the understanding of the design parameters which lead to lower NO sub(x) emissions from combustion systems. This paper presents data from experimental and modelling studies on the nitrogenous emissions from an oil fired furnace using staged combustion for the control of NO sub(x) emissions. Measurements of the in-flame NO concentration profiles are compared for the same burner operating in the unstaged and staged mode. The exit gas NO concentration was reduced by 30% during staged combustion with 35% secondary air. A post-processing NO model linked to the output from a commercial computational code was used to predict the rates of formation and concentrations of thermal, fuel and prompt-NO from the experimental system. The predictions showed that NO emission is in good qualitative agreement with the experimentally observed values when the effects of superequilibrium radical formation and turbulence/chemistry interaction are considered.