Axially staged premixed combustion chamber

Abstract

A combustor for a gas turbine includes a plurality of radially outer nozzles arranged in an annular array, each of the radially outer nozzles having an outlet end located to supply fuel and/or air to a first combustion chamber. A center nozzle has an outlet end located axially upstream of the outlet ends of the radially outer nozzles, and is configured and arranged to supply fuel and air to a second combustion chamber axially upstream of the first combustion chamber. The second combustion chamber opens into the first combustion chamber and has a length sufficient to maintain a center nozzle flame confined to the second combustion chamber.

1 . A combustor for a gas turbine comprising:
 a plurality of radially outer nozzles arranged in a substantially annular array, each of said radially outer nozzles having an outlet end located to supply fuel and/or air to a first combustion chamber;   at least a center nozzle having an outlet end located axially upstream of said outlet ends of said radially outer nozzles, configured and arranged to supply fuel and air to a second combustion chamber axially upstream of said first combustion chamber, said second combustion chamber opening into said first combustion chamber and having a length sufficient to maintain a center nozzle flame confined to said second combustion chamber.   
     
     
         2 . The combustor of  claim 1  wherein said outlet ends of said radially outer nozzles are supported in an annular plate, and wherein a tubular member defining said second combustion chamber extends from said annular plate in an upstream direction. 
     
     
         3 . The combustor of  claim 1  wherein means are provided for supplying either air alone, or air and fuel to said plurality radially outer nozzles. 
     
     
         4 . The combustor of  claim 3  wherein means are provided for supplying fuel and air to said center nozzle. 
     
     
         5 . The combustor of  claim 1  wherein, in addition to said center nozzle, one or more of said plurality of radially outer nozzles have outlet ends upstream of remaining ones of said plurality of radially outer nozzles. 
     
     
         6 . The combustor of  claim 5  wherein said one or more of said plurality of radially outer nozzles are configured and arranged to supply fuel and air to said second combustion chamber. 
     
     
         7 . A combustor for a gas turbine comprising:
 a plurality of nozzles arranged in a substantially annular array, each of said nozzles having an outlet end located to supply fuel and/or air to a first combustion chamber;   a center nozzle and at least one of said plurality of nozzles having outlet ends located axially upstream of said outlet ends of remaining ones of said plurality of nozzles, configured and arranged to supply fuel and air to a second combustion chamber axially upstream of said first combustion chamber, said second combustion chamber opening into said first combustion chamber and having a length sufficient to maintain a center nozzle flame and a flame of said at least one of said plurality of nozzles confined to said second combustion chamber.   
     
     
         8 . The combustor of  claim 7  wherein said outlet ends of said radially outer nozzles except for said at least one of said plurality of nozzles are supported in an annular plate, and wherein a tubular member defining said second combustion chamber extends from said annular plate in an upstream direction. 
     
     
         9 . The combustor of  claim 7  wherein means are provided for supplying either air alone, or air and fuel, to said plurality of radially outer nozzles. 
     
     
         10 . The combustor of  claim 9  wherein means are provided for supplying fuel and air to said center nozzle. 
     
     
         11 . A method of operating a gas turbine having at least one combustor supplied with fuel and/or air through a plurality of nozzles including an outer array of nozzles surrounding a center nozzle, the method comprising:
 a. at no- or low-load conditions, supplying fuel and air to said center nozzle and air only to said outer array of nozzles while isolating a flame generated by said center nozzle from air flowing through said outer array of nozzles; and   b. at higher load conditions, supplying a fuel/air mixture through both said outer array of nozzles and said center nozzle such that flames generated by said outer array of nozzles are maintained in a first combustion chamber and a flame generated by said center nozzle is maintained in a second combustion chamber upstream of said first combustion chamber.   
     
     
         12 . The method of  claim 11  further comprising:
 c. extinguishing said flame generated by said center nozzle; and 
 d. reigniting a new flame generated by said center nozzle, with said new flame anchored in said first combustion chamber. 
 
     
     
         13 . The method of  claim 11  wherein said first combustion chamber has a length sufficient to burn off CO at low or no-load levels. 
     
     
         14 . The method of  claim 11  including cooling a tubular member defining said second combustion chamber. 
     
     
         15 . The method of  claim 14  wherein said cooling is carried out by anyone of impingement cooling, thermal barrier coating, turbulators or any combination thereof. 
     
     
         16 . The method of  claim 11  wherein step (a) is carried out with respect to at least one additional nozzle in said outer array of nozzles. 
     
     
         17 . The method of  claim 11  wherein step (a) is carried out at full speed/no load conditions. 
     
     
         18 . The method of  claim 11  wherein step (b) is carried out at full speed/no load conditions. 
     
     
         19 . The method of  claim 17  wherein the method of  claim 11  wherein step (b) is carried out at full speed/no load conditions.