Burner tube premixer and method for mixing air and gas in a gas turbine engine

Abstract

A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of slots formed in the burner tube and configured to introduce air flows tangentially into the burner tube and impart swirl to the air flows; a plurality of fuel passages extending axially along the burner tube; and a plurality of fuel injection holes provided to each fuel passage. At least one of the fuel injection holes of each fuel passage is configured to inject a fuel flow tangentially into the burner tube between air flows of adjacent slots to form a fuel and air co-flow. A method of mixing air and fuel in a burner of a gas turbine is provided. The burner includes a burner tube including a plurality of slots formed in the burner tube. The method includes introducing air flows tangentially into the burner tube through the slots and imparting swirl to the air flows; and injecting fuel between air flows of adjacent slots to form fuel and air co-flows. This eliminates jet cross flow, which tends to cause flame holding. The tangentially entered fuel and air co-flow layers then flow down axially with quick mixing and dump to a combustor for a stable premixed combustion.

1 . A burner for use in a gas turbine engine, comprising:
 a burner tube having an inlet end and an outlet end;   a plurality of slots formed in the burner tube and configured to introduce air flows tangentially into the burner tube and impart swirl to the air flows;   a plurality of fuel passages extending axially along the burner tube; and   a plurality of fuel injection holes provided to each fuel passage, wherein at least one of the fuel injection holes of each fuel passage is configured to inject a fuel flow tangentially into the burner tube between air flows of adjacent slots to form a fuel and air co-flow.   
   
   
       2 . A burner according to  claim 1 , further comprising a central body coaxially disposed in the burner tube between the inlet end and the outlet end. 
   
   
       3 . A burner according to  claim 2 , wherein the central body converges from the inlet end to the outlet end. 
   
   
       4 . A burner according to  claim 2 , wherein the central body comprises a central passage. 
   
   
       5 . A burner according to  1 , wherein each slot comprises a slot end that directs the air flow tangential to the axis of the burner tube. 
   
   
       6 . A burner according to  1 , wherein each slot comprises a slot end that directs the air flow radially. 
   
   
       7 . A burner according to  claim 1 , wherein each fuel passage is formed between an exterior wall and an interior wall of the burner tube. 
   
   
       8 . A burner according to  claim 7 , wherein each fuel flow of each co-flow is separated from the interior wall of the burner tube. 
   
   
       9 . A burner according to  claim 2 , wherein the co-flows are not separated from the central body. 
   
   
       10 . A burner according to  claim 1 , wherein the number of slots corresponds to the number of fuel passages. 
   
   
       11 . A burner according to  claim 1 , wherein the plurality of slots comprises four slots. 
   
   
       12 . A method of mixing air and fuel in a burner of a gas turbine, the burner including a burner tube comprising a plurality of slots formed in the burner tube, the method comprising
 introducing air flows tangentially into the burner tube through the slots and imparting swirl to the air flows; and   injecting fuel between air flows of adjacent slots to form fuel and air co-flows.   
   
   
       13 . A method according to  claim 12 , wherein each fuel flow is separated from an interior wall of the burner tube by an air flow. 
   
   
       14 . A method according to  claim 12 , wherein injecting the fuel comprises injecting the fuel tangentially into the burner tube. 
   
   
       15 . A method according to  claim 12 , further comprising injecting air flow tangentially to the burner tube axis at ends of the slots. 
   
   
       16 . A method according to  claim 12 , further comprising injecting air flow radially to the burner tube at ends of the slots. 
   
   
       17 . A method according to  claim 12 , further comprising accelerating the co-flows through the burner tube along a central body coaxially disposed in the burner tube. 
   
   
       18 . A method according to  claim 17 , wherein accelerating the co-flows comprises maintaining no flow separation at a surface of the central body. 
   
   
       19 . A method according to  claim 17 , further comprising providing purge air through a central passage of the central body.