Inshot burner flame retainer

Abstract

A flame retainer for an inshot burner has a plurality of secondary openings that take full advantage of the space available to limit their size in one dimension to prevent flashbacks but are sufficient in size to allow for the flow of sufficient primary air so as to prevent yellow tipping and soot formation. The slots are elongated in radially cross-sectional shape, and their widths are limited to a dimension of 0.13 inches. The width is also limited to dimensions equal to or greater than 0.09 inches so as to prevent the formation of soot.

1 . A burner insert for placement within an outlet end of an inshot burner nozzle, said burner insert having an axially elongated annular body with an axially extending inner flow passage and further comprising: 
 a plurality of axially extending secondary openings formed in said insert, said secondary openings being radially spaced from said inner flow passage and at least some of said secondary openings being formed as elongated slots in radial cross-sectional shape.    
   
   
       2 . A burner insert as set forth in  claim 1  wherein said elongated slots have a uniform width which is equal to or less than 0.13 inches.  
   
   
       3 . A burner insert as set forth in  claim 2  wherein said slot width is equal to or greater than 0.09 inches.  
   
   
       4 . A burner insert as set forth in  claim 1  wherein said secondary openings are generally V-shaped in radial cross-sectional shape.  
   
   
       5 . A burner insert as set forth in  claim 4  wherein said V-shaped openings having their apex extending towards said inner flow passage.  
   
   
       6 . A burner insert as set forth in  claim 4  wherein said secondary openings have a relationship as follows:  
       b  14   N≅ 126.56−0  wherein N=the number of V-shaped openings and θ=½ the included angle of the V-shaped opening.    
   
   
       7 . A burner insert as set forth in  claim 1  include a plurality of openings having a circular radial cross sectional shape.  
   
   
       8 . A burner insert as set forth in  claim 1  wherein the space between said secondary openings is no less than 0.045 inches.  
   
   
       9 . A method of preventing flashback in a flame retainer of an inshot burner nozzle for use with propane comprising the steps of: 
 providing an insert having an axially elongated annular body with an axially extending inner flow passage;    providing a plurality of axially extending openings in said insert, said secondary openings being radially spaced from said inner flow passage and at least some of said secondary passages being formed as elongated slots in radial cross sectional shape.    
   
   
       10 . A method as set forth in  claim 9  and including the further step of limiting the width of said secondary passages to be equal to or less than 0.13 inches.  
   
   
       11 . A method as set forth in  claim 10  and including the further step of forming the secondary passages such that the width of the slots is uniform and is equal to or greater than 0.09 inches.  
   
   
       12 . A method as set forth in  claim 9  wherein said at least some of said secondary openings are generally V-shaped in radial cross sectional shape.  
   
   
       13 . A method as set forth in  claim 9  wherein said plurality of secondary openings are formed such that the thickness of the walls therebetween is no less than 0.045 inches.