Two major environmental problems limiting combustion processes in furnaces are the emissions of nitrogen oxides and fine particles. Mechanisms of nitrogen oxide pollutant formation and destrucion has been researched for many decades, since the nineteen sixities. The chemical kinetics are nwo well understo9od, and this understanding has led to pollutant abatement measures such as staged combustion and reburning. Not currently available is a quantitiative understanding of the coupling between flame aerodynamics/mixing and NO_x formation/destruction kinetics. This paepr presents recent reseach results from the Universtiy of Arozona and the US EPA on how poor, non ideal mixing, such as are obtained in diffusion flaes, can be exploited to allow NO_x reduction by reburning under overall fuel lean conditions, where premixed kinetic mechanisms suggest reburning to be ineffective.One especially interesting results was how the transition from laminar to turbulent diffusion flames affected the order of NO reduction with respect to NO.
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