Pollutant Formation in Furnaces: NOx and Fine Particulates

Two major environmental problems that limit combustion processes in furnaces are emission of nitrogen oxides and emission of fine particles. Mechanisms of nitrogen oxide pollutant formation and destruction have been researched for many decades. The chemical kinetics are now well understood, and this understanding has led to pollutant abatement measures such as staged combustion and reburning. Not currently available is a quantitative understanding of the coupling between flame aerodynamics/mixing and NOx formation/destruction kinetics. This paper presents research results describing how poor, non ideal mixing, such as are obtained in diffusion flames, can be exploited to allow NOx reduction by reburning under overall fuel lean conditions, where premixed kinetic mechanisms suggest reburning to be ineffective. One especially interesting result was that the transition from laminar to turbulent diffusion flames affected the apparent order of NO reduction with respect to NO. The other problem that is of environmental concern is that of fine particle emissions. This paper describes results on the partitioning of trace metals in fine particles during the combustion of coal. A relatively new result is that the particle size distribution from coa