Frustoconical burner can assembly

DETAILED DESCRIPTION What is claimed is: 1.
In a gun type burner having a fuel injector for discharging a conical spray pattern centrally of a surrounding blast tube and means for supplying pressurized air to said tube, the improvement comprising; a perforated, frustoconical burner can surrounding, and concentric with, the downstream end of said injector spray pattern; said burner can comprising the downstream wall of a preheating plenum chamber surrounding said injector for defining, with said conical spray pattern, a rotationally static frustoconical fuel/air mixing zone; said plenum chamber including a plurality of upstream inlet passages for admitting substantially the entire air flow through said blast tube to said plenum chamber and whose aggregate cross-section exceeds that of the burner can perforations; means for directing substantially the entire flow of air in said blast tube through said upstream passages; said burner can perforations being symmetrically disposed about the burner can axis; and said frustoconical burner can exhibiting a perforated to non-perforated surface area ratio decreasing from a maximal adjacent the smaller upstream end thereof to a minimal adjacent the downstream end thereof and then increasing, at the extreme downstream end thereof, to a value intermediate said maximal and minimal ratios.
2.
The burner of claim 1 wherein the burner can perforations at said extreme downstream end thereof comprise flame shaping perforations arranged in a circular array whose diameter approaches the internal diameter of said blast tube to shape and project a generally cylindrical flame.
3.
The burner of claim 2 wherein said plenum inlet passages are arranged in a circular array whose diameter approximates that of the aforesaid flame shaping array; and the remainder of said burner can perforations, upstream of said flame shaping array, comprising mixing perforations arranged in a plurality of circular arrays having substantially smaller diameters than said inlet passage array whereby air traversing said plenum chamber to exit said mixing perforations follows a reentrant flow path