Heater for asphalt concrete roadways and the like

Claim 2

Equipment according to claim 1, each burner having walls within which the expansion of the gases is guided and retarded.

Claim 3

Equipment according to claim 1 in which the burners are arranged in a checkerboard pattern in said chamber, the radially expanding lower portion of each flame being arrested by encountering lower portions of surrounding flames.

Claim 4

Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising chamber-forming walls including a roof wall adapted to overlie an area to be heated by combined radiation and direct contact heating, and said walls including downwardly extending peripheral side wall portions that leave only a small crack between their lower edges and said pavement; power air blower supply and heating means for producing a multiplicity of flames in said chamber below said roof; said flames being spaced closely enough to merge and substantially entirely fill said chamber with quiescent lambent flame; exhaust means having an exit flow path through said chamber-forming walls for removal of the products of combustion from within said chamber, each flame being associated with a burner, each burner having walls within which the expansion of gases is guided and retarded to issue into the chamber with a flow cross-section many times greater than where ignition takes place, with corresponding reduction in linear velocity, certain of said burners, identified for convenience as lower burners, defining small chambers shaped to direct and entering stream of gas into small vortexes with their vertical axes in continuation of the direction of entry, whereby the movement of gas in circles in radial planes containing the axis of a small vortex substantially reduces the linear distance flame propagation must travel to reach every point in the circling mass; the entire vortex changing into direct downward flow to contact the pavement.

Claim 5

Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising chamber-forming walls including a roof wall adapted to overlie an area to be heated by combined radiation and direct contact heating, and said walls including downwardly extending peripheral side wall portions that leave only a small crack between their lower edges and said pavement; power air blower supply and heating means for producing a multiplicity of flames in said chamber below said roof; said flames being spaced closely enough to merge and substantially entirely fill said chamber with quiescent lambent flames; and exhaust means having an exit flow path through said chamber-forming walls for removal of the product of combustion from within said chamber, certain of said flames originating in conical, downwardly opening cavities in the lower surface of said roof, with ignition over a small circle intermediate the ends of said cones propagating radially both inward and outward to build an approximately spherical bulb having tangential contact with its cone and with the pavement.

Claim 6

Equipment according to claim 6 in which an open-mesh screen lies in each flame, said screen being of material adapted to emit radiation of relatively short wavelengths efficient in heating light colored material.

Claim 7

Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising chamber-forming walls including a roof wall adapted to overlie an area to be heated by combined radiation and direct contact heating, and said walls including downwardly extending peripheral side walL portions that leave only a small crack between their lower edges and said pavement; power air blower supply and heating means for producing a multiplicity of flames in said chamber below said roof; exhaust means having an exit flow path through said chamber-forming walls for removal of the products of combustion from within said chamber, a mixing chamber to receive compressed air from said power blower; fuel supply conduit means for delivering fuel to said mixing chamber; and a multiplicity of mixture conduits, one for each flame, receiving combustible mixture from said mixing chamber and delivering to each flame its aliquot portion of mixture.

Claim 8

Equipment according to claim 8 in which said fuel supply conduit means has a portion having heat transfer contact with said blowtorch for preheating the fuel en route to said mixing chamber.

Claim 9

Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising chamber-forming walls including a roof wall adapted to overlie an area to be heated by combined radiation and direct contact heating, and said walls including downwardly extending peripheral side wall portions that leave only a small crack between their lower edges and said pavement; power air blower supply and heating means for producing a multiplicity of flames in said chamber below said roof; exhaust means having an exit flow path through said chamber-forming walls for removal of the products of combustion from within said chamber, and conduit seeding means provided for returning to the inlet of said power blower a minor fraction of the fresh exhaust gases from said chamber.

Claim 10

Equipment for heating the upper strata of asphalt concrete pavement or the like comprising chamber-forming means including a roof for overlying an area to receive the heat and downwardly extending wall portions that leave only a small crack between said wall portions and said area, means for producing a multiplicity of closely spaced flames substantially in said chamber such that the flames substantially entirely fill the chamber with lambent flame, and means defining an exit flow path through said chamber-forming means for the removal of the products of combustion within the chamber; the wall surface of said chamber being of a material that radiates a major portion of its radiant heat at red and infra-red wavelengths, and said chamber also containing a multiplicity of members associated with respective flame producing means for radiating a substantial amount of energy in the visible spectrum above red.