The Impact of Scaling Criteria on the Characteristics of Pulverised Coal Flames

Abstract

AbstractResults are presented of a series of experiments where a 12 MW, large‐scale swirl stabilised burner is compared with two 2.5 MW, geometrically similar burners designed around a constant‐velocity and constant‐residence‐time scaling criterion. High and low NOx flames were produced from all burners and selected flames were extensively probed to determine in‐flame thermo‐chemical structures. Results show that complex differences exist between flames. Results are also presented on the effect of scale on the ignition properties of axial turbulent jet flames. Experimental findings show an important effect of ignition distance on NOx that has important implications with respect to scaling effects on these flame types. The results detailed in the text are interpreted with reference to the effect of scale on turbulent mixing, two‐phase interactions and ignition properties. Results confirm that, regardless of the scaling criterion selected, similarity of the in‐flame thermochemical features is almost impossible to maintain as burner scale is changed irrespective of the scaling approach employed.