Low NOx staged fuel injection burner for creating plug flow

Abstract

A burner for producing a plug-like flow and low NOx emissions. The burner has a central air jet and plural staged fuel jets surrounding the central jet. The ratio of the sum of the momentums of vector components of the staged jets along respective axes parallel to the central longitudinal axis of the central jet to the momentum of the central jet along that axis is within the range of 0.5 to 1.5 and most preferably 0.8.

1 . A staged fuel burner for establishing a plug-like flow in a furnace, said staged burner comprising: a central nozzle and plural staged nozzles, said central nozzle having an orifice for producing a jet comprising air directed along a central longitudinal axis, said staged nozzles surrounding said central nozzle, each of said staged nozzles having at least one orifice for producing a staged jet comprising fuel, each of said staged jets being directed along a respective longitudinal axis and having a vector component in a direction parallel to said central longitudinal axis, whereby the sum of the momentums of said vector components of said staged jets parallel to said central longitudinal axis is approximately 50% to 150% of the momentum of the central jet along said central longitudinal axis. 
   
   
       2 . The staged fuel burner of  claim 1  wherein said sum of the momentums of said vector components of said staged jets parallel to said central longitudinal axis is approximately 80% to 100% of the momentum of the central jet along said central longitudinal axis. 
   
   
       3 . The staged fuel burner of  claim 2  wherein said sum of the momentums of said vector components of said staged jets parallel to said central longitudinal axis is approximately 80% of the momentum of the central jet along said central longitudinal axis. 
   
   
       4 . The staged fuel burner of  claim 1  additionally comprising means for supplying fuel to said staged nozzles and means for supplying air to said central nozzle. 
   
   
       5 . The staged fuel burner of  claim 4  additionally comprising means for supplying air to said staged nozzles, whereupon said staged jets comprise fuel and air. 
   
   
       6 . The staged fuel burner of  claim 4  wherein said burner additionally comprises means for supplying fuel to said central nozzle. 
   
   
       7 . (canceled) 
   
   
       8 . The staged fuel burner of  claim 1  wherein each orifice includes a respective exit plane and wherein the ratio of the sum of the momentums of the vector components of said staged jets parallel to said central longitudinal axis to the momentum of the central jet along said central longitudinal axis is a ratio (MR) defined by the formula: 
     
       
         
           
             MR 
             = 
             
               
                 ∑ 
                 
                   
                     
                       m 
                       . 
                     
                     
                       s 
                       , 
                       i 
                     
                   
                    
                   
                     V 
                     i 
                   
                    
                   cos 
                    
                   
                       
                   
                    
                   
                     θ 
                     i 
                   
                 
               
               
                 
                   
                     m 
                     . 
                   
                   c 
                 
                  
                 
                   V 
                   c 
                 
               
             
           
         
       
     
     where {dot over (m)} is mass flow rate of the identified jet, V is velocity of the identified jet at the exit plane of the orifice from which the jet projects, θ is the included angle between the central longitudinal axis and the respective longitudinal axes of said staged nozzles, and the subscripts s, c, I represent staged, central and i-th number of staged nozzles. 
   
   
       9 . The staged fuel burner of  claim 1  wherein said respective longitudinal axes of said staged jets extend parallel to said central longitudinal axis. 
   
   
       10 . The staged fuel burner of  claim 1  wherein said longitudinal axis of at least one of said staged jets extends at an outward diverging angle to said central longitudinal axis. 
   
   
       11 . The staged fuel burner of  claim 10  wherein said longitudinal axes of all of said staged jets extends at an outward, diverging angle to said central longitudinal axis. 
   
   
       12 . The staged fuel burner of  claim 1  wherein said longitudinal axis of at least one of said staged jets extends San inward, converging angle to said central longitudinal axis. 
   
   
       13 . The staged fuel burner of  claim 10  wherein said longitudinal of all of said staged jets extends at an inward, converging angle to said central longitudinal axis. 
   
   
       14 . The staged fuel burner of  claim 1  wherein said orifices of said staged burners have a common exit plane. 
   
   
       15 . The staged fuel burner of  claim 14  wherein said orifice of said central nozzle has an exit plane that is located forward of said common exit plane of said staged burners. 
   
   
       16 . The staged fuel burner of  claim 14  wherein said orifice of said central nozzle has an exit plane that is located rearward of said common exit plane of said staged burners. 
   
   
       17 . The staged fuel burner of  claim 14  wherein said orifice of said central nozzle has an exit plane that is coplanar with said common exit plane of said staged burners. 
   
   
       18 . The staged fuel burner of  claim 1  wherein said orifices of said staging nozzles are the same size and shape. 
   
   
       19 . The staged fuel burner of  claim 1  wherein said orifices of said staging nozzles are different sizes and/or shapes. 
   
   
       20 . A method of establishing a plug like flow of burning fuel in a furnace comprising:
 (A) providing staged burner comprising a central nozzle and plural staged nozzles surrounding said central nozzle, said central nozzle having an orifice arranged for producing a jet comprising air directed along a central longitudinal axis, said staged nozzles surrounding said central nozzle, each of said staged nozzles having at least one orifice and arranged for producing a staged jet comprising fuel, each of said staged jets being directed along a respective longitudinal axis and having a vector component in a direction parallel to said central longitudinal axis,   (B) providing a fluid comprising air to said central nozzle, whereupon said central nozzle produces a jet comprising air directed along said central longitudinal axis, and   (C) providing a fluid comprising fuel to said staged nozzles, whereupon said staged nozzles produce respective staged jets comprising fuel along said respective longitudinal axes, whereby the sum of the momentums of said vector components of said staged jets parallel to said central longitudinal axis is approximately 50% to 150% of the momentum of the central jet along said central longitudinal axis.   
   
   
       21 . The method  claim 20  wherein said sum of the momentums of said vector components of said staged jets parallel to said central longitudinal axis is approximately 80% to 100% of the momentum of the central jet along said longitudinal axis. 
   
   
       22 . The method of  claim 21  wherein said sum of the momentums of said vector components of said staged jets parallel to said central longitudinal axis is approximately 80% of the momentum of the central jet along said longitudinal axis. 
   
   
       23 . The method of  claim 20  additionally comprising supplying air to said staged nozzles, whereupon said staged jets comprise fuel and air. 
   
   
       24 . The method of  claim 20  wherein additionally comprising supplying fuel to said central nozzle, whereupon said central jet comprises air and fuel. 
   
   
       25 . The method of  claim 20  additionally comprising providing combustion products to said central nozzle, whereupon said central jet comprises air and combustion products. 
   
   
       26 . The method of  claim 20  wherein each orifice includes a respective exit plane and wherein the ratio of the sum of the momentums of the vector components of said staged jets parallel to said central longitudinal axis to the momentum of said central jet along said central longitudinal axis is a ratio (MR) defined by the formula: 
     
       
         
           
             MR 
             = 
             
               
                 ∑ 
                 
                   
                     
                       m 
                       . 
                     
                     
                       s 
                       , 
                       i 
                     
                   
                    
                   
                     V 
                     i 
                   
                    
                   cos 
                    
                   
                       
                   
                    
                   
                     θ 
                     i 
                   
                 
               
               
                 
                   
                     m 
                     . 
                   
                   c 
                 
                  
                 
                   V 
                   c 
                 
               
             
           
         
       
     
     where {dot over (m)} is mass flow rate of the identified jet, V is velocity of the identified jet at the exit plane of the orifice from which the jet projects, θ is the included angle between the central longitudinal axis and the respective longitudinal axes of said staged nozzles, and the subscripts s, c, i represent staged, central and i-th number of staged nozzles.