Method and gas turbine combustion system for safely mixing h2-rich fuels with air

Abstract

A method and apparatus are disclosed for mixing H2-rich fuels with air in a gas turbine combustion system, wherein a first stream of burner air and a second stream of a H2-rich fuel are provided. All of the fuel is premixed with a portion of the burner air to produce a pre-premixed fuel/air mixture. This pre-premixed fuel/air mixture is injected into the main burner air stream.

1 . A method for mixing H2-rich fuels with air in a gas turbine combustion system, comprising:
 providing a first stream of burner air and a second stream of a H2-rich fuel;   premixing the fuel with a portion of the burner air to produce a pre-premixed fuel/air mixture; and   injecting this pre-premixed fuel/air mixture into a main burner air stream.   
     
     
         2 . The method according to  claim 1 , wherein the premixing is done in a manner for preventing flame anchoring at undesired locations, including at least one of near an injection location and in a burner. 
     
     
         3 . The method according to  claim 1 , wherein an air excess factor of λ>1, is achieved in the premixing. 
     
     
         4 . The method according to  claim 1 , comprising:
 separating air into O2 and N2 with an air separation unit; and   adding a portion of the N2 from the air separation unit to at least one of the main burner air and the pre-premixed fuel/air mixture.   
     
     
         5 . The method according to  claim 1 , comprising:
 using a pre-premixer formed as a channel with straight or slightly swirling air flow to avoid at least one of recirculation and stagnation regions.   
     
     
         6 . The method according to  claim 1 , comprising:
 using a pre-premixer having narrow channels whose hydraulic diameter is less than a quenching distance.   
     
     
         7 . The method according to  claim 5 , comprising:
 energizing boundary layers of the air flow in the pre-premixer by using some film air, in order to increase velocities in the at least one recirculation and stagnation regions.   
     
     
         8 . The method according to  claim 7 , comprising:
 accelerating the air flow additionally via a jet-pump effect of injecting large volumes of H2/N2 fuel.   
     
     
         9 . The method according to  claim 1 , comprising:
 injecting water mist into the H2-rich fuel for cooling due to a subsequent evaporation of injected water.   
     
     
         10 . The method according to  claim 1 , comprising:
 utilizing a main swirler in a swirl-stabilized burner to further increase velocity in a pre-premixer by taking advantage that local static pressure in a central region of the burner is lower than a nominal burner pressure.   
     
     
         11 . The method according to  claim 1 , wherein an air excess factor of λ>1, is achieved in the premixing. 
     
     
         12 . The method according to  claim 1 , comprising:
 using a pre-premixer formed as a channel with straight or slightly swirling air flow to avoid recirculation and/or stagnation regions.   
     
     
         13 . A gas turbine combustion system, comprising:
 a combustion chamber and at least one burner opening into the combustion chamber for injecting a stream of burner air into the combustion chamber; and   at least one pre-premixer for providing a pre-premixed fuel/air mixture;   whereby the at least one burner and the at least one pre-premixer are arranged relative to each other, such that the pre-premixed fuel/air mixture will be injected into the stream of burner air during operation.   
     
     
         14 . A gas turbine combustion system according to  claim 11 , wherein the at least one pre-premixer is formed as a channel with straight or slightly swirling air flow. 
     
     
         15 . A gas turbine combustion system according to  claim 11 , wherein the at least one pre-premixer includes narrow channels whose hydraulic diameter is less than a quenching distance. 
     
     
         16 . A gas turbine combustion system according to  claim 11 , wherein the at least one burner is a swirl-stabilized burner. 
     
     
         17 . A gas turbine combustion system according to  claim 11 , wherein the at least one burner is an AEV burner. 
     
     
         18 . A gas turbine combustion system according to  claim 11 , wherein the at least one burner is an SEV burner. 
     
     
         19 . A gas turbine combustion system according to  claim 11 , wherein the at least one pre-premixer is formed as a channel with straight or slightly swirling air flow. 
     
     
         20 . A gas turbine combustion system according to  claim 11 , wherein the at least one burner is a swirl-stabilized burner.