Low swirl injector and method for low-nox combustor

Abstract

A fuel injector and a combustor including a fuel injector that enables a combustor to burn a lean fuel/oxider gas mixture while providing low emissions of oxides of nitrogen (NO x ), and a method of combustion. The fuel injector includes three fuel/oxider flow path channels. The first channel includes a flow balancing insert and provides a relatively straight flow. The second channel includes at least one angled vane that imparts a swirl to the flow. The third channel is a central tube, the first channel annularly surrounding the third channel, the second channel annularly surrounding the first channel.

1 . A low swirl injector for use with a combustor, the low swirl injector comprising:
 at least one passage adapted to provide a fuel gas and an oxidant gas, at least one of said fuel gas and said oxidant gas establishing an axial gas flow through said injector,   a first channel adapted for passage of said gas flow, said first channel disposed to direct said gas flow to the combustor,   a flow balancing insert disposed within said gas flow through said first channel, said flow balancing insert introducing additional pressure drop beyond that occurring in the first channel without said flow balancing insert,   a second channel disposed annularly about said first channel and adapted for passage of said gas flow, said second channel including at least one vane oriented to impart angular momentum to the gas flow exiting said second channel, and   a third channel having an inlet disposed to receive a feed gas, and an outlet aligned to direct said feed gas to said combustor.   
   
   
       2 . The low swirl injector of  claim 1  wherein the first channel is disposed annularly about the third channel. 
   
   
       3 . The low swirl injector of  claim 1  wherein the feed gas includes at least one of the following: pure fuel or a premix of fuel and a second oxidant gas. 
   
   
       4 . The low swirl injector of  claim 1  wherein said feed gas and fuel gas include a same fuel. 
   
   
       5 . The low swirl injector of  claim 1  wherein said at least one passage including at least one passage adapted to provide said fuel gas and at least one passage adapted to provide said oxidant gas. 
   
   
       6 . The low swirl injector of  claim 5  said at least one passage adapted to provide said fuel gas includes a plurality of passages including a hollow interior and at least orifice opening from the hollow interior into at least one of said first or second channels. 
   
   
       7 . The low swirl injector of  claim 6  further including at least one valve adapted to control flow of fuel gas to said first channel and at least one valve adapted to control flow of fuel gas to said second channel. 
   
   
       8 . The low swirl injector of  claim 1  wherein said at least one passage adapted to provide the fuel gas and the oxidant gas provides a premix of fuel gas and oxidant gas. 
   
   
       9 . The low swirl injector of  claim 1  wherein the flow balancing insert comprises at least one of a porous material, a perforated screen, a wire mesh, a porous ceramic material, a porous polymeric material, a porous metallic material, or a plate comprising at least one opening therethrough. 
   
   
       10 . The low swirl injector of  claim 2  including a passage adapted to provide oxidant gas to the first and second channels, and a plurality of passages adapted to provide said fuel gas to the first and second channels, said plurality of passages including a hollow interior and at least one orifice opening from the hollow interior into at least one of said first or second channels, said plurality of passages being substantially radially disposed, and wherein the flow balancing insert comprises a plate having a plurality of openings therethrough. 
   
   
       11 . A combustor comprising:
 a combustion zone,   a mix zone opening to said combustion zone,   a low swirl injector including
 at least one passage adapted to provide a fuel gas and an oxidant gas, at least one of said fuel gas and said oxidant gas establishing an axial gas flow, 
 a first channel having an entrance disposed to accept said gas flow, and an exit aligned to direct said gas flow into the mix zone, 
 a flow balancing insert disposed within said gas flow through said first channel, said flow balancing insert introducing additional pressure drop beyond that occurring in the first channel without said flow balancing insert, 
 a second channel disposed annularly about said first channel to accept said gas flow and direct said gas flow to said mix zone, said second channel including at least one vane oriented to impart angular momentum to the gas flow exiting said second channel, 
 a third channel having an inlet disposed to receive a feed gas, and an outlet aligned to direct said feed gas into said mix zone, and 
   said gas flow from said first channel, said gas flow from said second channel, and said feed gas from said third channel interacting in said mix zone prior to the combustion zone.   
   
   
       12 . The combustor of  claim 11  wherein the first channel is disposed annularly about the third channel. 
   
   
       13 . The combustor of  claim 11  said at least one passage including at least one passage adapted to provide said oxidant gas to the first and second channels, and a plurality of passages adapted to provide fuel gas to the first and second channels, said plurality of passages including a hollow interior and at least one aperture opening from the hollow interior into at least one of said first or second channels. 
   
   
       14 . The combustor of  claim 13  further including at least one valve adapted to selectively provide fuel gas to said first channel and at least one valve adapted to selectively provide fuel gas to said second channel. 
   
   
       15 . The combustor of  claim 13  wherein the at least one passage adapted to provide oxidant gas comprises a restriction. 
   
   
       16 . The combustor of  claim 11  wherein the flow balancing insert comprises at least one of a porous material, a perforated screen, a wire mesh, a porous ceramic material, a porous polymeric material, a porous metallic material, or a plate comprising at least one opening therethrough. 
   
   
       17 . A method of combustion comprising the steps of:
 establishing an axial gas flow of a fuel gas and an oxidant gas through a first channel, through a flow balancing insert, and into a mix zone, said flow balancing insert introducing additional pressure drop beyond that occurring in the first channel without said flow balancing insert,   establishing an axial gas flow of said fuel gas and said oxidant gas through a second channel and into the mix zone, passing said axial gas flow through said second channel along at least one vane disposed within the second channel and oriented to impart an angular momentum to said gas flow through the second channel,   directing a feed gas into a third channel having an outlet aligned to direct said feed gas into said mix zone,   allowing said gas flow from said first channel, said gas flow from said second channel, and said feed gas from said third channel to interact in said mix zone, and   opening said mix zone into a combustion zone.   
   
   
       18 . The method of  claim 17  wherein the step of establishing an axial gas flow through said first channel includes steps of providing a flow of fuel gas to said first channel and providing a flow of oxidant gas to said first channel, and the step of establishing an axial gas flow through said second channel includes steps of providing a flow of fuel gas to said second channel and providing a flow of oxidant gas to said second channel. 
   
   
       19 . The method of  claim 18  wherein the steps of providing the flow of fuel gas to said first channel, providing the flow of oxidant gas to said first channel, providing the flow of fuel gas to said second channel and providing the flow of oxidant gas to said second channel, further comprise the step of establishing different fuel gas/oxidant gas ratios through the first and second channels. 
   
   
       20 . The method of  claim 16  wherein the step of establishing an axial flow through said flow balancing insert includes the step of establishing an axial flow through a plurality of openings in the flow balancing insert.