Patent ID: 8016590

Claim:
An assembly emitting low oxides of nitrogen following combustion while minimizing susceptibility to aero-acoustic coupling comprising: a combustion chamber having a base with a burner assembly extending thereinto from said base and including an exterior wall, a primary fuel stream, a primary oxidant stream, a secondary oxidant plenum, a secondary oxidant stream, a secondary fuel stream, and at least one secondary fuel injector; said secondary oxidant stream and said secondary fuel stream maintained separate from one another and unmixed with one another within said burner assembly; said combustion chamber having a primary combustion zone receiving a substantially stoichiometric amount of fuel and oxidant from said primary fuel stream and said primary oxidant stream, and a primary burner zone; said exterior wall extending from said base into said combustion chamber to adjacent to said primary combustion zone; said primary fuel stream and said oxidant stream being combusted in said primary combustion zone adjacent to said exterior wall and forming flue gases; said secondary oxidant plenum located adjacent to said exterior wall, said secondary oxidant plenum discharging said secondary oxidant stream into said combustion chamber at a discharge point near said base, said secondary oxidant stream entraining and mixing with said flue gases in said combustion chamber thus forming a secondary oxidant-flue gas mixture flowing towards said primary burner zone; said at least one secondary fuel injector injecting a secondary fuel stream at a discharge location downstream from said discharge point for said secondary oxidant stream and closer to said primary burner zone, said at least one secondary fuel injector located between said discharge point for said secondary oxidant stream and said primary burner zone; said secondary fuel stream mixing with said secondary oxidant-flue gas mixture forming a resultant oxidant-flue gas-fuel mixture flowing towards said primary burner zone of at least a velocity preventing ignition of said resultant oxidant-flue gas-fuel mixture while entraining and mixing with additional flue gases in said combustion chamber; and, said resultant oxidant-flue gas-fuel mixture being combusted adjacent to said primary combustion zone, said primary fuel stream and said primary oxidant stream merging with said resultant oxidant-flue gas-fuel mixture and flowing past said primary combustion zone into said combustion chamber.