Air augmented duct burner

Claim 1

In a burner of the type adapted for placement in a gas stream having an insufficient oxygen content to enable continuous ignition of fuel injected into the gas stream, the gas stream flowing in a downstream direction, the burner including a plurality of rigid members spaced across the gas stream, each member having an air impervious surface facing the upstream direction, the members defining spaced apart openings therethrough that are distributed over an effective, flame sustaining length of the surface, each opening having an inlet end in the surface facing in the upstream direction and an outlet end facing in the downstream direction, means for directing at said inlet ends fuel jets that have a dimension transversely of the inlet ends greater than the inlet ends so that a minor portion of the fuel in the jets flows along the surface and the major portion of the fuel enters the openings, and means upstream of the fuel jet directing means for shielding the inlet openings from the gas stream, the improvement comprising: an air duct disposed upstream of each air impervious surface, and means forming a passageway for directing a substantially homogeneous air flow from each air duct towards the corresponding impervious surface over the effective length of the surface, the last mentioned means preventing admixture of the air flow and the gas stream upstream of the impervious surfaces.