Fuel injector for low NOx and enhanced flame stabilization

Abstract

A fuel injector for use in a furnace is provided. The fuel injector is used to deliver pulverized fuel to a combustion chamber of a furnace. The structure of the fuel injector facilitates efficient combustion while stabilizing the combustion flame. As a result, a minimal amount of NO x and other undesirable byproducts are released into the atmosphere.

1 . A fuel injector for use in a furnace, said fuel injector comprising: 
 (a) an inner barrel having inlet and outlet ends, said inner barrel defining a passageway extending between said inlet and outlet ends through which a fuel stream including carrier gas and fuel particles are permitted to flow;    (b) an outer barrel surrounding at least a portion of said inner barrel and defining an outer passageway through which secondary air is permitted to flow;    (c) a plurality of stabilizer vanes arranged within said outer passageway near said outlet end of said inner barrel, the secondary air flowing through the outer passageway impacts said plurality of stabilizer vanes such that combustion of the fuel stream is maintained near said outlet end of said inner barrel;    (d) a plurality of axial vanes arranged within said outer passageway between said inner and outer barrels, each of said axial vanes being arranged between a corresponding pair of said stabilizer vanes, and functioning in concert with said stabilizer vanes to create a desired flow of the secondary air with respect to the fuel stream flowing from said outlet end; and    (e) a fixed vane swirler arranged within said outer passageway between said inner and outer barrels, said fixed vane swirler having a structure sufficient to create a rotational flow of the secondary air around said plurality of stabilizer and axial vanes.    
   
   
       2 . The fuel injector of  claim 1  further comprising an air control damper arranged within said outer passageway structured and arranged to control the quantity of the secondary air flowing through said fixed vane swirler.  
   
   
       3 . The fuel injector of  claim 1  wherein said plurality of stabilizer vanes are attached to said inner barrel.  
   
   
       4 . The fuel injector of  claim 1  wherein said plurality of axial vanes are attached to said inner barrel.  
   
   
       5 . The fuel injector of  claim 1  wherein said fixed vane swirler is attached to said outer barrel.  
   
   
       6 . The fuel injector of  claim 2  wherein said air control damper comprises a perforated plate and an axially movable sleeve.  
   
   
       7 . The fuel injector of  claim 1  wherein said outlet end of said inner barrel includes a plurality of elliptical sections adapted to create a plurality of concentrated fuel streams at said outlet end of said inner barrel.  
   
   
       8 . A furnace comprising: 
 (a) a housing;    (b) a combustion zone within said housing; and    (c) a fuel injector arranged to deliver at least one fuel stream to said combustion zone, said fuel injector including: (1) an inner barrel having inlet and outlet ends, said inner barrel defining a passageway extending between said inlet and outlet ends through which a fuel stream including carrier gas and fuel particles are permitted to flow, (2) an outer barrel surrounding at least a portion of said inner barrel and defining an outer passageway through which secondary air is permitted to flow, (3) a plurality of stabilizer vanes arranged within said outer passageway near said outlet end of said inner barrel, the secondary air flowing through the outer passageway impacts said plurality of stabilizer vanes such that combustion of the fuel stream is maintained near said outlet end of said inner barrel, (4) a plurality of axial vanes arranged within said outer passageway between said inner and outer barrels, each of said axial vanes being arranged between a corresponding pair of said stabilizer vanes, and functioning in concert with said stabilizer vanes to create a desired flow of the secondary air with respect to the fuel stream flowing from said outlet end, and (5) a fixed vane swirler arranged within said outer passageway between said inner and outer barrels, said fixed vane swirler having a structure sufficient to create a rotational flow of the secondary air around said plurality of stabilizer and axial vanes.    
   
   
       9 . The fuel injector of  claim 8  further comprising an air control damper arranged within said outer passageway structured and arranged to control the quantity of the secondary air flowing through said fixed vane swirler.  
   
   
       10 . The fuel injector of  claim 8  wherein said plurality of stabilizer vanes are attached to said inner barrel.  
   
   
       11 . The fuel injector of  claim 8  wherein said plurality of axial vanes are attached to said inner barrel.  
   
   
       12 . The fuel injector of  claim 8  wherein said fixed vane swirler is attached to said outer barrel.  
   
   
       13 . The fuel injector of  claim 9  wherein said air control damper comprises a perforated plate and an axially movable sleeve.  
   
   
       14 . The fuel injector of  claim 8  wherein said outlet end of said inner barrel includes a plurality of elliptical sections adapted to create a plurality of concentrated fuel streams at said outlet end of said inner barrel.  
   
   
       15 . The furnace of  claim 1  further comprising a plurality of fuel injectors.  
   
   
       16 . The fuel injector of  claim 15  further comprising an air control damper arranged within said outer passageway structured and arranged to control the quantity of the secondary air flowing through said fixed vane swirler.