Burner with high flow area tip

Abstract

An improved burner and a method for combusting fuel in burners used in furnaces, such as those used in steam cracking, are disclosed. The burner includes a burner tube having an upstream end and a downstream end and means for drawing flue gas from the furnace or air from a source of air or mixtures thereof in response to an inspirating effect of uncombusted fuel flowing through the burner tube from its upstream end towards its downstream end. A burner tip is mounted on the downstream end of the burner tube adjacent a first opening in the furnace, the burner tip having a plurality of main ports in an external surface thereof so that combustion of the fuel takes place downstream of the burner tip, the number and dimensions of said main ports in said external surface being such that the ratio of the total area of the main ports in said external surface is at least 1 square inch per million (MM) Btu/hr burner capacity. The inspirating effect of the fuel flowing though the burner tube can optionally be further assisted by steam injection upstream of the burner tube.

What is claimed is:  
     
         1 . A burner for the combustion of fuel in a furnace, said burner comprising: 
 (a) a burner tube having a downstream end and an upstream end;    (b) a fuel orifice located adjacent the upstream end of said burner tube, for introducing fuel into said burner tube;    (c) a burner tip mounted on the downstream end of said burner tube and adjacent a first opening in the furnace, said burner tip having a plurality of main ports in an external surface thereof so that combustion of the fuel takes place at said external surface of said burner tip, the number and dimensions of said main ports in said external surface being such that the total area of the main ports in said external surface is at least 1 square inch per million (MM) Btu/hr burner capacity; and    (d) means for drawing flue gas from said furnace or air from a source of air or mixtures thereof in response to an inspirating effect of uncombusted fuel flowing through said burner tube from its upstream end towards its downstream end.    
     
     
         2 . The burner according to  claim 1 , wherein the burner is a pre-mix burner.  
     
     
         3 . The burner according to  claim 1 , wherein the burner is a flat-flame burner.  
     
     
         4 . The burner according to  claim 1 , wherein said means for drawing flue gas from said furnace is in fluid communication with an external FGR duct.  
     
     
         5 . The burner of  claim 1 , wherein the total area of the main ports in said external surface is at least 1.2 square inch per million (MM) Btu/hr burner capacity.  
     
     
         6 . The burner of  claim 1 , further comprising a venturi intermediate said upstream end and said downstream end of said burner tube.  
     
     
         7 . The burner of  claim 6 , wherein said venturi includes a throat portion having substantially constant internal cross-sectional dimensions such that the ratio of the length to maximum internal cross-sectional dimension of said throat portion is at least 3.  
     
     
         8 . The burner of  claim 6 , wherein the ratio of the length to maximum internal cross-sectional dimension of said throat portion is from about 4 to about 10.  
     
     
         9 . The burner of  claim 6 , wherein the ratio of the length to maximum internal cross-sectional dimension of said throat portion is from about 4.5 to about 8.  
     
     
         10 . The burner of  claim 6 , wherein the ratio of the length to maximum internal cross-sectional dimension of said throat portion is from about 6.5 to about 7.5.  
     
     
         11 . The burner according to  claim 7 , including one or more steam tubes terminating adjacent the upstream end of said burner tube for introducing steam into said burner tube.  
     
     
         12 . The burner according to  claim 1 , including one or more steam tubes terminating adjacent the upstream end of said burner tube for introducing steam into said burner tube.  
     
     
         13 . The burner according to  claim 11 , further comprising at least one air port for introducing staged secondary air.  
     
     
         14 . The burner according to  claim 1 , further comprising at least one air port for introducing staged secondary air.  
     
     
         15 . The burner according to  claim 14  wherein said fuel orifice is located within a gas spud.  
     
     
         16 . The burner according to  claim 1  wherein said fuel orifice is located within a gas spud.  
     
     
         17 . A method for combusting fuel in a burner of a furnace, comprising the steps of: 
 (a) combining fuel with air, flue gas or a mixture thereof at a predetermined location adjacent a fuel orifice;    (b) passing the fuel and air, flue gas or mixture thereof through a burner tube;    (c) discharging the fuel and air, flue gas or mixture thereof at a burner tip downstream of the predetermined location, the burner tip having a plurality of main ports in an external surface thereof and a plurality of further side ports in a peripheral surface thereof; and    (d) combusting the fuel downstream of said burner tip,    wherein the total area of the main ports in said external surface of the burner tip is at least 1 square inch per million (MM) Btu/hr burner capacity.    
     
     
         18 . The method according to  claim 17 , wherein the burner is a pre-mix burner.  
     
     
         19 . The method according to  claim 17 , wherein the burner is a flat-flame burner.  
     
     
         20 . The method according to  claim 17 , wherein the burner further comprises an external FGR duct.  
     
     
         21 . The method according to  claim 17 , further comprising the step of injecting steam into the burner tube to mix with the fuel and air, flue gas or mixtures thereof upstream of said zone of combustion.  
     
     
         22 . The method according to  claim 21  wherein the furnace is a steam-cracking furnace.  
     
     
         23 . The method according to  claim 17  wherein the furnace is a steam-cracking furnace.  
     
     
         24 . The method of  claim 17  wherein said fuel orifice is located within a gas spud.  
     
     
         25 . The method of  claim 17  wherein the total area of the main ports in said external surface is at least 1.2 square inch per million (MM) Btu/hr burner capacity.