Abstract: A flashback resistant burner for lean fuel/air mixtures includes apparatus for mixing a primary fuel and combustion air to form a noncombustible fuel/air mixture. Means are provided for accelerating the noncombustible fuel/air mixture to a velocity higher than the flame speed of a combustible mixture of the primary fuel and air. Means are further provided for mixing a secondary fuel with the accelerated noncombustible fuel/air mixture to form a combustible fuel/air mixture that has an equivalence ratio less than 1. Means are then provided for burning the combustible fuel/air mixture.

Abstract: An improved method of burning a hydrocarbon fuel in a combustion system includes burning the fuel in a main burner under fuel-lean conditions to produce a main flame and burning a low heating value fuel in a pilot burner to stabilize the main flame and limit the amount of NO.sub.x produced in the pilot burner. The pilot fuel can inherently have a low heating value, can be a diluted high heating value fuel, or can be made by partially oxidizing a high heating value fuel. An improved combustion system for burning a hydrocarbon fuel with limited NO.sub.x emissions has a main burner, a pilot burner, and a partial oxidation stage capable of converting a high heating value fuel to a low heating value fuel in a partial oxidation reaction. The system also has means for burning the low heating value fuel in the pilot burner. The system can include means for removing heat from the partial oxidation stage or low heating value fuel to lower the temperature of the pilot flame.

Abstract: A method of combusting a hydrocarbon fuel includes mixing the fuel with a first air stream to form a fuel/air mixture having an equivalence ratio of greater than 1 and partially oxidizing the fuel by contacting it with an oxidation catalyst to generate a heat of reaction and a partial oxidation product stream. The partial oxidation product stream is mixed with a second air stream and completely combusted in a main combustor at a condition at which appreciable quantities of thermal NO.sub.x are not formed to generate an effluent gas stream, thereby generating an effluent gas stream containing decreased amounts of thermal and prompt NO.sub.x. A system for combusting a hydrocarbon fuel includes, in combination, means for mixing the fuel with a first air stream, a catalytic oxidation stage containing an oxidation catalyst, means for mixing the partial oxidation product stream with a second air stream, and a main combustor capable of completely combusting the partial oxidation product stream.