Patent ID: 8025501

Claim:
A combustion furnace comprising: a hollow interior which, during a normal operation of the furnace, is at a desired operating temperature; a floor at the bottom of the hollow interior; a source of pressured fuel gas; a source of combustion air; a gas burner adjacent the floor for combusting the fuel gas and combustion air, the gas burner including (a) a first passageway having a fuel gas outlet therein in fluid communication with the source of pressured fuel gas whereby the fuel gas required during normal operation of the furnace is injected from the fuel gas outlet and into the first passageway, an aperture disposed within the hollow interior and adjacent the floor and through which furnace gas from the hollow interior enters the first passageway and mixes with the injected fuel gas to form a mixture thereof, and a first outlet through which the mixture of furnace gas and fuel gas exits the first passageway, and (b) a second passageway separate from the first passageway having an inlet in fluid communication only with the source of combustion air during the normal operation so that only combustion air enters the second passageway during the normal operation, and a second outlet adjacent but separate from the first outlet, from which only combustion air exits the second passageway during the normal operation; and a combustion zone, located completely downstream of the gas burner and in the hollow interior, the combustion zone providing, during the normal operation and downstream of the gas burner, an initial mixing of the mixture of furnace gas and fuel gas exiting from the first outlet of the first passageway with only combustion air exiting from the second outlet of the second passageway so that a flame is produced by the combustion thereof only at a location downstream of the gas burner.