HIGH PERFORMANCE LOW NOx BURNER AND SYSTEM

Abstract

According to embodiments, burner systems include a distal flame holder and distal pilot burner formed at least partially from shared structure.

1 - 55 . (canceled) 
     
     
         56 . A low NOx burner, comprising:
 a main fuel nozzle disposed at a proximal position in a furnace and configured to output a main fuel into a combustion air stream;   a pilot burner disposed at a distal position and configured to support a pilot flame to initiate combustion of the mixed main fuel and combustion air; and   a distal flame holder positioned to receive the mixed main fuel and combustion air, and configured to hold a combustion reaction of the mixed main fuel and combustion air wherein the distal flame holder consists essentially of metal parts.   
     
     
         57 . The low NOx burner of  claim 56 , wherein the pilot burner and the distal flame holder at least partially share the same structure. 
     
     
         58 . The low NOx burner of  claim 56 , wherein the distal flame holder includes one or more bodies defining one or more pilot fuel passages; and
 wherein the one or more bodies define one or more apertures operatively coupled to the one or more pilot fuel passages, the one or more apertures being configured to operate as pilot fuel nozzles for outputting pilot fuel to support the pilot flame as a diffusion pilot flame.   
     
     
         59 . The low NOx burner of  claim 56 , wherein the pilot burner is a premix pilot burner supporting the pilot flame by combustion of a premixed mixture of pilot fuel and combustion air. 
     
     
         60 . (canceled) 
     
     
         61 . The low NOx burner of  claim 56  wherein the metal parts comprise stainless steel. 
     
     
         62 . The low NOx burner of  claim 56 , wherein the distal flame holder comprises a swirler. 
     
     
         63 . The low Nox burner of  claim 56 , wherein the distal flame holder comprises a V-gutter. 
     
     
         64 . The low Nox burner of  claim 63 , wherein the V-gutter defines crenelated edges. 
     
     
         65 . The low Nox burner of  claim 56 , further comprising a combustion air source configured to provide the combustion air stream. 
     
     
         66 . The low Nox burner of  claim 65 , further comprising a mixing tube disposed to receive the main fuel and combustion air stream into a proximal end of the mixing tube and to output mixed main fuel and combustion air at a distal end of the mixing tube. 
     
     
         67 . The low Nox burner of  claim 65 , wherein the combustion air source is configured to cause the stream of combustion air to educe flue gas into the proximal end of the mixing tube; and
 wherein the mixed main fuel and combustion air output at the distal end of the mixing tube includes mixed main fuel, combustion air, and flue gas.   
     
     
         68 . The low NOx burner of  claim 67 , wherein the educing of the flue gas into the proximal end of the mixing tube comprises internal flue gas recirculation. 
     
     
         69 . The low NOx burner of  claim 56 , further comprising a natural draft combustion air source configured to provide the combustion air stream. 
     
     
         70 . The low NOx burner of  claim 56 , wherein the low NOx burner is configured as a flare. 
     
     
         71 . The low NOx burner of  claim 56 , further comprising a forced draft combustion air source configured to provide the combustion air stream. 
     
     
         72 . The low NOx burner of  claim 71 , wherein the forced draft combustion air source comprises a blower. 
     
     
         73 . The low NOx burner of  claim 56 , wherein the low NOx burner is configured as a boiler burner. 
     
     
         74 . The low NOx burner of  claim 73 , further comprising a flame tube boiler configured to output heat from flame tubes carrying combustion products from the furnace, the output heat being arranged to heat water in a shell surrounding the flame tubes. 
     
     
         75 . The low NOx burner of  claim 73 , further comprising a water tube boiler having water tubes configured to transfer heat from the furnace to water flowing through the water tubes. 
     
     
         76 . The low NOx burner of  claim 75 , further comprising a superheater configured as steam tubes carrying steam, the superheater being disposed in a flue disposed to receive hot combustion products from the combustion reaction. 
     
     
         77 . The low NOx burner of  claim 73 , further comprising:
 a mounting flange configured to mount the low NOx burner to the furnace.   
     
     
         78 . The low NOx burner of  claim 76 , further comprising
 a mixing tube disposed to receive the main fuel and combustion air stream into a proximal end of the mixing tube and to output mixed main fuel and combustion air at a distal end of the mixing tube; and   one or more legs configured to mechanically couple the mixing tube to the mounting flange.   
     
     
         79 . The low NOx burner of  claim 78 , wherein the mixing tube mechanically supports the distal flame holder. 
     
     
         80 . The low NOx burner of  claim 56 , wherein the pilot burner is configured to be a continuous pilot burner, the continuous pilot burner being configured to maintain combustion of the mixed main fuel and combustion air. 
     
     
         81 . A method for operating a low NOx burner, comprising:
 receiving main fuel and combustion air into a proximal end of a mixing tube;   outputting mixed main fuel and combustion air from a distal end of the mixing tube;   receiving the mixed main fuel and combustion air at a distal flame holder; and   causing ignition of the mixed main fuel and combustion air at a location coincident with the distal flame holder with a pilot flame supported by a continuous pilot burner,
 wherein each of the continuous pilot burner and the distal flame holder at least partially include shared structure. 
   
     
     
         82 . The method of  claim 81 , further comprising providing the distal flame holder including a body defining at least one pilot fuel gallery inside the body, the body including an external aerodynamic surface adapted to cause one or more low pressure zones in flowing mixed fuel and combustion air and combustion gases reacted therefrom; and
 providing the continuous pilot burner by providing the body including a plurality of apertures providing for pilot fuel flow from the at least one pilot fuel gallery to a combustion volume outside the aerodynamic surface,
 whereby the pilot flame supported by the pilot fuel ignites the mixed main fuel and combustion air in a region defined by the aerodynamic surface. 
   
     
     
         83 . The method of  claim 82 , wherein the combustion volume outside the aerodynamic surface includes a volume adjacent to the aerodynamic surface. 
     
     
         84 . The method of  claim 81 , wherein receiving main fuel and combustion air includes receiving flue gas; and
 wherein receiving mixed main fuel and combustion air at the distal flame holder includes receiving mixed main fuel, combustion air, and flue gas at the distal flame holder.   
     
     
         85 . The method of  claim 81 , further comprising providing the main fuel and combustion air by providing respective main fuel nozzle(s) and a combustion air source. 
     
     
         86 . The method of  claim 85 , further comprising;
 pressurizing combustion air using a blower, the blower form least a portion of the combustion air source.   
     
     
         87 . The method of  claim 85 , further comprising:
 admitting a metered rate of combustion air using a natural draft combustion air register, the natural draft combustion air register forming at least a portion of the combustion air source.