Aerodynamic and diluent effects on the emission of nitrogen oxides from hydrocarbon diffusion flames

An experimental study of the quantities of oxides of nitrogen produced in hydrocarbon gas jet flames in concentric and cross‐flow air streams is presented. It is seen that the structure of flames has a strong influence on the quantities of NO and NO 2 generated in diffusion flames. Increases in jet velocity result in the increase of NO and NO 2 emitted from flames in concentric air streams. However, air stream velocity has opposite effects on the yields of NO and NO 2 from flames in cross‐flows. Additions of diluent to jet and air streams decrease NO and NO 2 in both concentric and cross‐flow air streams. The implications of scaling these results to fullsize flare stack flames have been discussed.