Combustion burner assembly having low oxides of nitrogen emission

Abstract

A combustion burner assembly having low oxides of nitrogen emission includes a mixing section having an air inlet, a fuel inlet and a fuel mixture outlet. Air is tangentially supplied to the mixing section through the air inlet. A pocket portion in the mixing section receives fuel from a fuel inlet. A plurality of holes in the pocket portion transfer fuel to the mixing section to form a fuel mixture with the air in the mixing section. A diffuser is disposed within the mixing section adjacent the fuel mixture outlet. The diffuser has a plurality of overlapping vanes disposed around an aperture that form a plurality of passages between each of the plurality of overlapping vanes through which the fuel mixture exits the mixing section. A pilot assembly is substantially disposed within the mixing section and passes through the aperture in the diffuser. The pilot assembly is adapted to produce a pilot light downstream of the diffuser that ignites the exiting fuel mixture to produce a high swirling flame, thereby resulting in a combustion burner assembly having low oxides of nitrogen emission.

1 . A combustion burner assembly, comprising: 
 a mixing section having an air inlet, a fuel inlet and a fuel mixture outlet, said air inlet supplying air tangentially to said mixing section;    a pocket portion in said mixing section to receive fuel from said fuel inlet;    a plurality of holes in said pocket portion to transfer fuel to said mixing section to form a fuel mixture with said air in said mixing section;    a diffuser disposed within said mixing section adjacent said fuel mixture outlet, said diffuser having a plurality of overlapping vanes disposed around an aperture forming a plurality of passages between each of said plurality of overlapping vanes through which said fuel mixture exits said mixing section; and    a pilot assembly substantially disposed within said mixing section and passing through said aperture in said diffuser, said pilot assembly adapted to produce a pilot light downstream of said diffuser to ignite said fuel mixture.    
   
   
       2 . A combustion burner assembly according to  claim 1 , wherein 
 said mixing section having a first end and a second end, said first end being said air inlet, said second end being said fuel mixture outlet.    
   
   
       3 . A combustion burner assembly according to  claim 2 , wherein 
 said first end is opposite said second end.    
   
   
       4 . A combustion burner assembly according to  claim 3 , wherein 
 said fuel inlet is positioned between said first end and said second end of said mixing section.    
   
   
       5 . A combustion burner assembly according to  claim 1 , wherein 
 said pilot assembly has a first tube supplying air and a second tube supplying fuel to produce the pilot light.    
   
   
       6 . A combustion burner assembly according to  claim 1 , wherein 
 each of said plurality of vanes has a width, each of said plurality of vanes overlapping by approximately half of said width.    
   
   
       7 . A combustion burner assembly according to  claim 1 , wherein 
 a plurality of spacers are disposed on an outer surface of said diffuser to space said diffuser from an inner surface of said mixing section.    
   
   
       8 . A combustion burner assembly according to  claim 7 , wherein 
 said plurality of spacers are a plurality of rods.    
   
   
       9 . A combustion burner assembly according to  claim 7 , wherein 
 said plurality of spacers are a plurality of dimples.    
   
   
       10 . A combustion burner assembly according to  claim 1 , wherein 
 a disk is disposed on said pilot assembly to reduce pressure within said mixing chamber to increase the velocity of the fuel mixture.    
   
   
       11 . A combustion burner assembly according to  claim 10 , wherein 
 said disk is disposed on said pilot assembly proximal said plurality of holes in said pocket portion.    
   
   
       12 . A combustion burner assembly according to  claim 1 , wherein 
 an air band is disposed around an outer surface of said diffuser to prevent flashback into said mixing section.    
   
   
       13 . A combustion burner assembly according to  claim 1 , wherein 
 an air damper supplies air to said air inlet of said mixing section, said air damper being positioned above said mixing section.    
   
   
       14 . A combustion burner assembly according to  claim 1 , wherein 
 an air damper supplies air to said air inlet of said mixing section, said air damper being positioned below said mixing section.    
   
   
       15 . A combustion burner assembly according to  claim 1 , wherein 
 a flange is disposed on an outer surface of mixing section, said flange being adapted to be rigidly secured to a heat exchanger.    
   
   
       16 . A combustion burner assembly, comprising: 
 a mixing section having a first end and a second end;    an adapter assembly connected to said first end of said mixing section;    an air damper connected to said air adapter, air being tangentially supplied to said adapter assembly to create swirling air flow through said mixing section;    a pocket portion in said mixing section to receive fuel from a fuel inlet;    a plurality of holes in said pocket portion to transfer fuel to said mixing section to form a swirling, premixed fuel mixture with said air in said mixing section;    a diffuser disposed within said mixing section adjacent said second end of said mixing section, said diffuser having a plurality of overlapping vanes disposed around an aperture forming a plurality of passages between each of said plurality of overlapping vanes through which said fuel mixture exits said second end of said mixing section; and    a pilot assembly substantially disposed within said mixing section and passing through said aperture in said diffuser, said pilot assembly adapted to produce a pilot light downstream of said diffuser to ignite said exiting fuel mixture.    
   
   
       17 . A combustion burner assembly according to  claim 16 , wherein said first end is opposite said second end.  
   
   
       18 . A combustion burner assembly according to  claim 16 , wherein said fuel inlet is positioned between said first end and said second end of said mixing section.  
   
   
       19 . A combustion burner assembly according to  claim 16 , wherein said pilot assembly has a first tube supplying air and a second tube supplying fuel to produce the pilot light.  
   
   
       20 . A combustion burner assembly according to  claim 16 , wherein each of said plurality of vanes has a width, each of said plurality of vanes overlapping by approximately half of said width.  
   
   
       21 . A combustion burner assembly according to  claim 16 , wherein a plurality of spacers are disposed on an outer surface of said diffuser to space said diffuser from an inner surface of said mixing section.  
   
   
       22 . A combustion burner assembly according to  claim 21 , wherein said plurality of spacers are a plurality of rods.  
   
   
       23 . A combustion burner assembly according to  claim 21 , wherein said plurality of spacers are a plurality of dimples.  
   
   
       24 . A combustion burner assembly according to  claim 16 , wherein a disk is disposed on said pilot assembly to reduce pressure within said mixing chamber to increase the velocity of said fuel mixture.  
   
   
       25 . A combustion burner assembly according to  claim 24 , wherein said disk is disposed on said pilot assembly proximal said plurality of holes in said pocket portion.  
   
   
       26 . A combustion burner assembly according to  claim 16 , wherein an air band is disposed around an outer surface of said diffuser to prevent flashback into said mixing section.  
   
   
       27 . A combustion burner assembly according to  claim 16 , wherein said air damper is positioned above said mixing section.  
   
   
       28 . A combustion burner assembly according to  claim 16 , wherein said air damper is positioned below said mixing section.  
   
   
       29 . A combustion burner assembly according to  claim 16 , wherein a flange is disposed on an outer surface of mixing section, said flange being adapted to be rigidly secured to a heat exhanger.  
   
   
       30 . A method of producing a combustion flame having low oxides of nitrogen emission, comprising the steps of: 
 supplying air tangentially to a mixing section of the burner assembly to create swirling air flow within the mixing section;    supplying fuel to the swirling air in the mixing section to form a premixed, swirling fuel mixture;    igniting a pilot assembly to produce a pilot light downstream of an exit of the mixing section;    passing the premixed, swirling fuel mixture through a diffuser in the mixing section upstream of the pilot light to spread out the fuel mixture; and    forming a combustion flame low in oxides of nitrogen emission by discharging the fuel mixture proximal the pilot light.    
   
   
       31 . The method of producing a combustion flame having low oxides of nitrogen emission of  claim 30 , further comprising 
 increasing the velocity of the fuel mixture by decreasing the pressure within the mixing section by disposing a disk on the pilot assembly.