Low nox burner

Abstract

Disclosed is a burner tip to be used in a furnace for the combustion of fuel gas in the combustion zone of a furnace, that comprises a burner tube that has a longitudinal axis and has a dowstream end and an upstream end for receiving the fuel gas.

1 . Burner tip to be used in a furnace for the combustion of fuel gas in the combustion zone of said furnace, comprising a burner tube having a longitudinal axis and having a downstream end and an upstream end for receiving the fuel gas, wherein,
 the furnace comprises means to introduce an effective amount of air into the combustion zone to cause the combustion of the fuel gas,   the burner tube extends through an opening in the wall or floor into the combustion zone,   the burner tube comprises a plurality of primary ports to deliver the primary fuel gas in the combustion zone, said primary ports are located in the combustion zone in order to create the fuel-lean combustion zone,   a bluff body is attached to the tube, located close to the primary ports which deliver the primary fuel gas and between said ports and the upstream end of the burner tube,   the bluff body is designed to produce, in the vicinity of the ports which deliver the primary fuel gas, an air speed as low as possible, such as the said primary fuel gas is given sufficient residence time to ignite,   the burner tube comprises a plurality of secondary ports to deliver the secondary fuel gas in the combustion zone,   said secondary ports are located in the flue gas zone (or outside the combustion zone) in order to create a fuel-rich zone,   said secondary ports are located between the primary ports and the downstream end.   
     
     
         2 . Burner tip according to  claim 1  wherein the bluff body is a plurality of fins. 
     
     
         3 . Burner tip according to  claim 1  wherein the bluff body is a cone having a symetrical axis essentially in line with the longitudinal axis of the burner tube. 
     
     
         4 . Burner tip according to  claim 2  wherein the fins are made of a solid plate. 
     
     
         5 . Burner tip according to  claim 1  wherein the bluff body is designed to produce, in the vicinity of the ports which deliver the primary fuel gas, an air speed lower than the flame speed such as the said primary fuel gas is given sufficient residence time to ignite. 
     
     
         6 . Burner tip according to  claim 1  having primary ports and secondary ports wherein the diameter between the primary ports and secondary ports is reduced as compared with the section between the upstream end and the primary ports. 
     
     
         7 . Burner tip according to  claim 6  wherein the reduction in diameter is done gradually in order to prevent recirculations and dead zones. 
     
     
         8 . Burner tip according to  claim 2  wherein the fins are made of a perforated plate. 
     
     
         9 . Burner tip according to  claim 3  wherein the cone is made of a solid plate. 
     
     
         10 . Burner tip according to  claim 3  wherein the cone is made of a perforated plate. 
     
     
         11 . Burner tip according to  claim 1  wherein other ports are located after the secondary ports having regards to the fuel gas flow from the upstream end to the downstream end.