The Stability of Premixed Flame on Water-Cooled Copper Slot

Through experimental research on a new-style water-cooled copper burner, the critical width of natural gas for back-fire was determined between 1.5 and 2 mm, which was much smaller than the number given in general reference. The burner was applied on a condensing boiler upside down. The out-flame limits on copper slot, combusting normally and inversely, were determined. The out-flame limits combusting inversely are not quite different from the normal on and they are just little bigger. Within the range 0.6～5.0W/mm2 of thermal intensity of fire port, primary air ratios are in the extent of 1.6～1.4 at out-flame, which is suitable for small domestic gas burner.