Burner for gaseous fuels of differing calorific values using preheated combustion air

摘要

A multi-fuel gas burner using preheated forced draft air, comprising a cylindrical inner burner tube (12), supported by the wall of a furnace (34) and inserted into an opening in the wall, means (94, 95, 96 and 97) being provided to inject through the upstream end combustion air preheated to a selected temperature and compressed to a selected pressure. The downstream end of the inner burner tube is closed and a plurality of longitudinal slots (72) are circumferentially spaced in the wall of the tube at the closed end. Means (18) are provided to inject rich fuel gas up to 3,500 btu_/cu feet under selected pressure into the inner bumer tube along its axis. An outer burner tube (22) axially surrounds the inner burner tube and forms an annular passage (49) therebetween. Means (28) are also provided to pass low pressure, lean, combustible gas of as low as 50 btu/cu feet down the annular passage (49) and outwardly through a circumferential slot (56) at the end of the outer burner tube inside the furnace. The hot combustion air and rich gas flowing through the inner tube and radially outwardly and rearwardly through the plurality of slots, flow against the mix with the lean gas flowing outwardly through the circumferential slot, and burn against the surface (38) of a tile (36), having a central opening, through which the burner is inserted into the furnace.