Combustor for a gas turbine

Abstract

A combustor for a gas turbine includes a pre-combustion chamber, a swirler, a burner plenum, wherein the swirler and the burner plenum surround the pre-combustion chamber in a circumferential direction with respect to the centre axis of the combustor. The swirler has a plurality of slots through which an oxidant/fuel mixture is injectable into the pre-combustion chamber, the each slot with at least a fuel injector through which fuel is injectable into the slot. The peripheral wall of the pre-combustion chamber includes a plurality of mixing holes downstream of the swirler for letting a portion of the oxidant gas in burner plenum to flow from the burner plenum to the pre-combustion chamber.

1 . A combustor for a gas turbine, the combustor comprising:
 a pre-combustion chamber having a peripheral wall around a centre axis (Y) of the pre-combustion chamber,   a swirler which is mounted to the pre-combustion chamber,   a burner plenum inside which an oxidant flows,   wherein the swirler surrounds the pre-combustion chamber in a circumferential direction with respect to the centre axis (Y),   wherein the burner plenum surrounds the pre-combustion chamber in a circumferential direction with respect to the centre axis (Y),   wherein the swirler comprises a plurality of slots through which a part of the oxidant flows and into the pre-combustion chamber,   wherein at least one slot comprises at least one fuel injector through which fuel is injectable into the slot,   wherein the peripheral wall of the pre-combustion chamber comprises a plurality of mixing holes downstream of the swirler for letting a portion of the oxidant in burner plenum to flow from the burner plenum to the pre-combustion chamber.   
     
     
         2 . The combustor according to  claim 1 ,
 wherein in a longitudinal plane (YZ) including the centre axis (Y) the mixing holes are inclined of a first mixing angle (α) with respect to centre axis (Y), the value of the first mixing angle (α) being lower than 90°.   
     
     
         3 . The combustor according to  claim 2 ,
 wherein the value of first mixing angle (α) is comprised between 30° and 60°.   
     
     
         4 . The combustor according to  claim 2 ,
 wherein the mixing holes are inclined towards the swirler.   
     
     
         5 . The combustor according to  claim 2 , further comprising:
 a combustion chamber downstream of the pre-combustion chamber and wherein the mixing holes are inclined towards the combustion chamber.   
     
     
         6 . The combustor according to  claim 1 ,
 wherein in a transversal plane (XZ) orthogonal to the centre axis (Y) the mixing holes are inclined of a second mixing angle (β) with respect to a radial direction (X), the value of the second mixing angle (β) being lower than 90°.   
     
     
         7 . The combustor according to  claim 6 ,
 wherein the value of second mixing angle (β) is comprised between 30° and 60°.   
     
     
         8 . The combustor according to  claim 6 ,
 wherein the mixing holes are inclined in the transversal plane (XZ) towards the negative direction of a circumferential swirl (W) flowing inside the pre-combustion chamber.   
     
     
         9 . The combustor according to  claim 1 ,
 wherein the hole axis (Z 1 ) of each of the mixing holes lies on a plane which is inclined of a third mixing angle (θ) with respect to centre axis (Y) of the pre-combustion chamber, the value of the third mixing angle (θ) being lower than 90°.   
     
     
         10 . The combustor according to  claim 9 ,
 wherein the value of third mixing angle (θ) is comprised between 30° and 60°.   
     
     
         11 . The combustor according to  claim 1 , further comprising,
 at least a base fuel injector arranged to a bottom surface of the swirler, the base fuel injector being inclined of an angle comprised between 30° and 60° with respect to the centre axis (Y).   
     
     
         12 . The combustor according to  claim 1 , further comprising,
 at least a side fuel injector arranged to a peripheral surface of the swirler.   
     
     
         13 . The combustor according to  claim 1 , further comprising:
 a pilot burner upstream the pre-combustion chamber which comprises a pilot burner surface separating the pilot burner from the pre-combustion chamber,   wherein the pilot burner comprises a pilot fuel injector which is arranged to the pilot burner surface for injecting pilot fuel into the pre-combustion chamber.   
     
     
         14 . A method for operating a combustor comprising:
 a pre-combustion chamber having a peripheral wall around a centre axis (Y) of the pre-combustion chamber,   a swirler which is mounted to the pre-combustion chamber, a burner plenum inside which an oxidant flows,   wherein the swirler surrounds the pre-combustion chamber in a circumferential direction with respect to the centre axis (Y),   wherein the burner plenum surrounds the pre-combustion chamber in a circumferential direction with respect to the centre axis (Y),   wherein the swirler comprises a plurality of slots through which a part of the oxidant flows and into the pre-combustion chamber,   wherein the each slot comprises at least one fuel injector through which the fuel is injectable into the slot,   the method including comprising: the step of
 letting a portion of the oxidant in burner plenum to flow from the burner plenum to the pre-combustion chamber, downstream of the swirler. 
   
     
     
         15 . The method according to  claim 14 , further comprising:
 orienting the portion of the oxidant gas flowing from the burner plenum to the pre-combustion chamber towards the swirler and towards the negative direction of a circumferential swirl (W) flowing inside the pre-combustion chamber.  4