Premix burner system for low BTU gas fuel

Claim 1

A premix burner system for alternate or simultaneous combustion of low BTU (100 BTU per cubic foot or less) higher BTU gaseous fuels in a furnace comprising; (a) an inner tube, and means to supply higher BTU gas under pressure to the upstream end of said inner tube; (b) a larger concentric outer tube surrounding said inner tube, forming an annular space therebetween, said annular space closed at the upstream end; and means to supply said low BTU gas under pressure to said annular space; (c) a downstream outlet for said inner and outer tubes terminating opposite and spaced from a burner tube whereby primary air is inducted and mixed with said gases for flow in said burner tube, means to control the flow of said primary air into said burner tube; (d) a burner head comprising a long narrow rectangular structure transversely connected to said burner tube, said head tapered inwardly in the downstream direction; (e) a furnace having a floor with a rectangular opening therein selectively larger than the dimensions of said burner heads; said opening tapering in the same direction as said burner head; (f) means to support said burner below said furnace floor with said burner head inserted into said opening; (g) a secondary air plenum surrounding said burner tube and leading to the annular space between said burner head and said opening in said furnace floor; and including means to control the flow of air into said secondary air plenum; (h) an enclosure means surrounding the primary and secondary air inlet portion of said burner system, forming a combustion air plenum; and (i) means for vertical adjustment of said burner head in said opening.