Blowpipe type of burner

Claim 1

A blowpipe type of burner including a cylindrical housing, a nozzle body provided with a mixing chamber, an axial gas inlet port to said mixing chamber, a plurality of radial air inlet ports to said mixing chamber, and an axially extending burner tube connected to said mixing chamber, whereby mixed gas is substantially completely burned in said burner tube, the improvement, in combination with said burner, of a self-cooling shield, said shield comprising: (a) a disc-like, centrally apertured baffle secured at the extreme forward end of said cylindrical housing, and having said axially extending burner tube projecting through said central aperture; (b) an outer tubular member, secured concentrically to said cylindrical housing by a disc-like centrally apertured rear wall, said central aperture surrounding said cylindrical housing and being secured thereto, thereby to provide said outer tubular member as having a closed rear end and an annular open forward end; (c) an inner tubular member secured concentrically within said outer tubular shield and to said disc-like baffle by a plurality of bracing connections, thereby to provide said inner tubular member as having an annular open rear end and a circular open forward end; (d) said outer tubular member and said inner tubular member defining, therebetween, an annular chamber for back-flow of cooling air; (e) the rear wall of said outer tubular member and said disc-like baffle defining, therebetween, a rear cylindrical chamber; and (f) said cylindrical housing having aperture means communicating said rear cylindrical chamber with said radial air inlet ports of said mixing chamber whereby cooling air is drawn in laminar flow into said annular chamber from the annular open end of said outer tubular member to said rear cylindrical chamber, where said air is bifurcated into two flows, a first air flow to provide combustion-supporting air to said radial air inlets, and a second air flow to enter the annular open rear end of said inner tubular member and then to be expelled, along with hot gaseous products of combustion, through an annular zone within, and along the wall of, said inner tubular member.