Method for low NOx combustion of syngas/high hydrogen fuels

Abstract

The present invention provides a method for low NOx combustion of high hydrogen content fuels in gas turbines. In the method of the present invention, at least a portion of the fuel is combusted under fuel rich conditions and a portion of resulting reaction heat is transferred to combustion air prior to non-premixed combustion of the fuel.

1 . The method of achieving low NOx in operation of a gas turbine non-premixed combustion system comprising: 
 a) obtaining a supply of fuel;    b) obtaining a supply of air;    c) forming a fuel rich mixture of the fuel with a first percentage of the air;    d) reacting the fuel rich mixture to produce partial reaction products plus heat;    e) transferring a sufficient amount of heat to a second percentage of the air; and    f) combusting the partial reaction products on contact with the heated second percentage of the air.    
     
     
         2 . The method of  claim 1  wherein the fuel comprises syngas.  
     
     
         3 . The method of  claim 2  wherein the syngas comprises gasified coal.  
     
     
         4 . The method of  claim 1  wherein the fuel comprises hydrogen.  
     
     
         5 . The method of  claim 1  wherein the turbine is operated at the design turbine inlet temperature for natural gas fuels.  
     
     
         6 . The method of  claim 1  wherein the fuel comprises a carbon reduced syngas.  
     
     
         7 . The method of  claim 1  wherein the amount of heat transferred to the second percentage of air lowers the stoichiometric adiabatic flame temperature of the partial reaction products on contact with the heated air to a specified temperature.  
     
     
         8 . The method of  claim 6  wherein the specified temperature is at least 200 degrees Celsius lower than that of remaining unreacted fuel.  
     
     
         9 . The method of either  claim 2  or  claim 3  wherein the amount of air in the fuel rich mixture represents at least about ten percent of the total supply of air.  
     
     
         10 . The method of either  claim 2  or  claim 3  wherein the amount of air in the fuel rich mixture represents at least about twenty percent of the total supply of air.