LOW NOx BURNER APPARATUS AND METHOD

Abstract

A burner apparatus for a fired-heater system and a method of burner operation wherein the burner fuel is ejected outside of the burner wall from a surrounding fuel discharge ring, or from a lateral elongate ejection bar in the case of a flat flame burner, to a combustion zone projecting from the forward end of burner wall. The burner apparatus and method reduce NO x production by a combination of enhanced internal flue gas recirculation and staged fuel operation.

What is claimed is: 
     
         1 - 10 . (canceled) 
     
     
         11 . A burner apparatus comprising:
 (a) a burner wall having a combustion zone projecting from or proximately from a forward end of said burner wall, wherein
 said burner wall surrounds a flow passageway for air or other oxygen-containing gas which extends longitudinally through said burner wall, 
 said flow passageway has a longitudinally forward discharge opening at said forward end of said burner wall, and 
 said flow passageway has at least one side at said forward discharge opening which is substantially flat and 
   (b) an elongate fuel discharge conduit which extends laterally outside of said one side of said flow passageway and is positioned longitudinally rearward of said forward end of said burner wall for discharging a burner fuel,
 wherein said elongate fuel discharge conduit includes either (i) a plurality of fuel discharge openings which extend along at least most of said elongate fuel discharge conduit and are oriented in a direct or angled forward direction to deliver said burner fuel outside of said burner wall to said combustion zone during operation or (ii) a single fuel discharge slot which extends along at least most of said elongate fuel discharge conduit and is oriented in a direct or angled forward direction to deliver said burner fuel outside of said burner wall to said combustion zone during operation. 
   
     
     
         12 . The burner apparatus of  claim 11  wherein said elongate fuel discharge conduit includes said plurality of fuel discharge openings and said plurality of fuel discharge openings are round holes spaced from about 0.5 to about 200 diameters apart. 
     
     
         13 . The burner apparatus of  claim 11  wherein:
 said forward end of said burner wall has a laterally extending outer edge on said one side of said flow passageway; 
 said elongate fuel discharge conduit includes said single fuel discharge slot; and 
 said single fuel discharge slot is oriented to eject said burner fuel toward said laterally extending outer edge of said forward end of said burner wall. 
 
     
     
         14 . The burner apparatus of  claim 13  wherein said burner wall further includes an outer fuel impact ledge which is positioned between said elongate fuel discharge conduit and said laterally extending outer edge of said forward end of said burner wall. 
     
     
         15 . The burner apparatus of  claim 11  wherein:
 said forward end of said burner wall has a laterally extending outer edge on said one side of said flow passageway; 
 said elongate fuel discharge conduit includes said plurality of fuel discharge openings; and 
 at least a portion of said plurality of fuel discharge openings are oriented to eject said burner fuel toward said laterally extending outer edge of said forward end of said burner wall. 
 
     
     
         16 . The burner apparatus of  claim 15  wherein said burner wall further includes an outer fuel impact ledge which is positioned between said elongate fuel discharge conduit and said laterally extending outer edge of said forward end of said burner wall. 
     
     
         17 . The burner apparatus of  claim 11  wherein said elongate fuel discharge conduit is positioned outside of said burner wall. 
     
     
         18 . A method of operating a burner comprising the steps of:
 (a) delivering an oxygen-containing gas through a flow passageway surrounded by a burner wall, said burner wall having a longitudinal axis which extends through said flow passageway, said flow passageway having a longitudinally forward discharge opening at a forward end of said burner wall, and said forward end of said burner wall having an outer lateral shape, wherein a combustion zone projects forwardly from or proximately from said forward end of said burner wall, and   (b) discharging a flow of burner fuel forwardly from a fuel discharge ring such that said flow of burner fuel is received in said combustion zone,
 wherein said fuel discharge ring is positioned outside of said flow passageway and longitudinally rearward of said forward end of said burner wall and 
 said flow of burner fuel, as it is discharged from said fuel discharge ring, has a lateral cross-sectional shape which substantially surrounds said flow passageway and corresponds to said outer lateral shape of said forward end of said burner wall. 
   
     
     
         19 . The method of  claim 18  wherein said fuel discharge ring includes a plurality of fuel discharge openings substantially surrounding said flow passageway from which said flow of burner fuel is discharged. 
     
     
         20 . The method of  claim 19  wherein said plurality of fuel discharge openings are round holes spaced from about 0.5 to about 5 diameters apart. 
     
     
         21 . The method of  claim 19  wherein:
 said forward end of said burner wall has an outer edge and 
 at least a portion of said plurality of fuel discharge openings eject said burner fuel toward said outer edge of said forward end of said burner wall. 
 
     
     
         22 . The method of  claim 18  wherein said fuel discharge ring is circular. 
     
     
         23 . A burner apparatus comprising:
 (a) a burner wall having a combustion zone projecting forwardly from or proximately from a forward end of said burner wall, wherein
 said burner wall surrounds a flow passageway for air or other oxygen-containing gas which extends longitudinally through said burner wall and 
 said flow passageway has a longitudinally forward discharge opening at said forward end of said burner wall and 
   (b) a fuel discharge structure which is positioned outside of said flow passageway for discharging a burner fuel, said fuel discharge structure substantially surrounding, laterally, said flow passageway,
 wherein said fuel discharge structure includes either (i) a plurality of fuel discharge openings which substantially surround said flow passageway and are oriented in a direct or angled forward direction to deliver said burner fuel outside of said burner wall to said combustion zone during operation or (ii) a single fuel discharge slot which substantially surrounds said flow passageway and is oriented in a direct or angled forward direction to deliver said burner fuel outside of said burner wall to said combustion zone during operation. 
   
     
     
         24 . The burner apparatus of claim  1  wherein said fuel discharge structure is a fuel discharge ring which substantially surrounds, laterally, said flow passageway. 
     
     
         25 . The burner apparatus of  claim 24  wherein said fuel discharge ring is longitudinally rearward of said forward end of said burner wall. 
     
     
         26 . The burner apparatus of  claim 25  wherein said fuel discharge ring includes said plurality of fuel discharge openings and said plurality of fuel discharge openings are round holes spaced from about 0.5 to about 5 diameters apart. 
     
     
         27 . The burner apparatus of  claim 25  wherein said burner wall has a circular cross-sectional shape and said fuel discharge ring is circular. 
     
     
         28 . The burner apparatus of  claim 25  wherein:
 said forward end of said burner wall has an outer edge; 
 said fuel discharge ring includes said plurality of fuel discharge openings; and 
 at least a portion of said plurality of fuel discharge openings are oriented to eject said burner fuel toward said outer edge of said forward end of said burner wall. 
 
     
     
         29 . The burner apparatus of  claim 28  wherein said burner wall further includes an outer fuel impact ledge which is positioned between said fuel discharge ring and said outer edge of said forward end of said burner wall and which surrounds said burner wall. 
     
     
         30 . The burner apparatus of  claim 23  wherein:
 said forward end of said burner wall has an outer edge; 
 said fuel discharge structure includes said single fuel discharge slot; and 
 said single fuel discharge slot is oriented to eject said burner fuel toward said outer edge of said forward end of said burner wall. 
 
     
     
         31 . The burner apparatus of  claim 30  wherein said fuel discharge structure is a fuel discharge ring which substantially surrounds, laterally, said flow passageway. 
     
     
         32 . The burner apparatus of  claim 31  wherein said fuel discharge ring is longitudinally rearward of said forward end of said burner wall. 
     
     
         33 . The burner apparatus of  claim 32  wherein said burner wall further includes an outer fuel impact ledge which is positioned between said fuel discharge ring and said outer edge of said forward end of said burner wall and which surrounds said burner wall. 
     
     
         34 . The burner apparatus of  claim 23  wherein said fuel discharge structure is a fuel discharge ring positioned outside of said burner wall. 
     
     
         35 . The burner apparatus of  claim 34  further comprising a plurality of delivery risers which deliver said burner fuel to said fuel discharge ring. 
     
     
         36 . The burner apparatus of  claim 35  further comprising an outer sleeve, different from said burner wall, which surrounds said delivery risers. 
     
     
         37 . The burner apparatus of  claim 23  wherein said burner fuel comprises a gas fuel. 
     
     
         38 . The burner apparatus of  claim 23  wherein said burner fuel comprises a liquid fuel.