System and method using low emissions gas turbine cycle with partial air separation

Abstract

A system and method of reducing gas turbine nitric oxide emissions includes a first combustion stage configured to burn air vitiated with diluents to generate first combustion stage products. A second combustion stage is configured to burn the first combustion stage products in combination with enriched oxygen to generate second combustion stage products having a lower level of nitric oxide emissions than that achievable through combustion with vitiated air alone or through combustion staging alone.

1 . A method of reducing gas turbine nitric oxide emissions, the method comprising:
 vitiating air with diluents;   introducing the vitiated air to a first combustion stage of a gas turbine and generating first combustion stage combustion products therefrom;   enriching the products of combustion from the first stage with oxygen in a second combustion stage; and   burning the products of combustion from the first stage in combination with enriched oxygen gas to generate second combustion stage products having a lower level of nitric oxide emissions than that achievable through combustion with vitiated air alone or through combustion staging alone.   
     
     
         2 . The method according to  claim 1 , wherein vitiating air with diluents comprises vitiating air with nitrogen. 
     
     
         3 . The method according to  claim 1 , further comprising partially separating air to generate the enriched oxygen gas. 
     
     
         4 . The method according to  claim 1 , further comprising partially separating air to generate the diluents. 
     
     
         5 . The method according to  claim 4 , wherein partially separating air to generate the diluents comprises partially separating air to generate enriched nitrogen gas. 
     
     
         6 . The method according to  claim 1 , further comprising burning a predetermined gas turbine fuel in combination with the vitiated air to generate the first combustion stage products. 
     
     
         7 . The method according to  claim 1 , wherein introducing the vitiated air to a first combustion stage of a gas turbine and generating first combustion stage combustion products therefrom comprises introducing the vitiated air to a first combustion stage of a dry low emissions combustor. 
     
     
         8 . The method according to  claim 1 , wherein introducing the vitiated air to a first combustion stage of a gas turbine and generating first combustion stage combustion products therefrom comprises introducing the vitiated air to a first combustion stage of a dry low nitric oxide combustor. 
     
     
         9 . The method according to  claim 1 , wherein burning the products of combustion from the second stage in combination with enriched oxygen gas to generate second combustion stage products having a lower level of nitric oxide emissions than that achievable through combustion with vitiated air alone or through combustion staging alone comprises burning the products of combustion from the second stage in combination with enriched oxygen gas to generate second combustion stage products having a nitric oxide level of less than 10 parts per million of the second combustion stage products. 
     
     
         10 . The method according to  claim 1 , further comprising burning the products of combustion from the second stage in combination with enriched oxygen gas to generate second combustion stage products having a lower level of nitric oxide emissions than that achievable through combustion with vitiated air alone or through combustion staging alone while maintaining combustion efficiency and carbon monoxide emissions at levels achievable through combustion with vitiated air alone or through combustion staging alone.