System and method for low emissions combustion

Abstract

A turbine system comprises a compressor for compressing air to generate a compressed flow, an air separation unit for receiving and separating at least a portion of the compressed flow into oxygen and a low-oxygen stream, a combustor for receiving and combusting at least a portion of the low-oxygen stream, a portion of the compressed flow and a fuel to generate a high temperature exhaust gas, and a turbine for receiving and expanding the high temperature exhaust gas to generate electricity and a reduced temperature low-NOx exhaust gas.

1 . A turbine system comprising:
 a compressor for compressing a first stream of air to generate a compressed flow;   an air separation unit for receiving and separating a second stream of air into oxygen and a low-oxygen stream;   a combustor for receiving and combusting at least a portion of said low-oxygen stream, a portion of said compressed flow and a fuel to generate a high temperature exhaust gas; and   a turbine for receiving and expanding said high temperature exhaust gas to generate electricity and a reduced temperature low-NOx exhaust gas.   
     
     
         2 . A turbine in accordance with  claim 1 , wherein said low-oxygen stream has less than about 20% by volume of oxygen. 
     
     
         3 . A turbine in accordance with  claim 1 , wherein said low-oxygen stream has less than about 15% by volume of oxygen. 
     
     
         4 . A turbine in accordance with  claim 1 , wherein said low-NOx exhaust gas has a NOx level of less than about 30 ppm. 
     
     
         5 . A turbine in accordance with  claim 1 , wherein said low-NOx exhaust gas has a NOx level of less than about 10 ppm. 
     
     
         6 . A turbine in accordance with  claim 1 , wherein said low-NOx exhaust gas is directed to a HRSG for the generation of steam and a reduced temperature exhaust gas. 
     
     
         7 . A turbine in accordance with  claim 6 , wherein said steam is directed to a bottoming cycle for the generation of additional electricity. 
     
     
         8 . A turbine in accordance with  claim 6 , wherein said reduced temperature exhaust gas is split into a first portion that is directed to a carbon dioxide capture system and a second portion that is directed to said compressor for compression along with said first stream of air. 
     
     
         9 . A turbine in accordance with  claim 6 , further comprising a heat exchanger, wherein said second portion and said low-oxygen stream are directed into said heat exchanger for heat exchange therebetween. 
     
     
         10 . A turbine system comprising:
 an air separation unit for separating air into oxygen and a low-oxygen stream;   a compressor for compressing air and at least a portion of said low-oxygen stream to generate a mixed compressed flow;   a combustor for receiving and combusting at least a portion of said mixed compressed flow and a fuel to generate a high temperature exhaust gas; and   a turbine for receiving and expanding said high temperature exhaust gas to generate electricity and a reduced temperature low-NOx exhaust gas.   
     
     
         11 . A turbine system in accordance with  claim 10 , wherein said compressor comprises at least a first-stage compressor section and a second-stage compressor section. 
     
     
         12 . A turbine system in accordance with  claim 11 , wherein said low-oxygen stream is directed into said second-stage compressor section for mixing with a compressed flow from said first-stage compressor section. 
     
     
         13 . A turbine system in accordance with  claim 11 , further comprising an intercooler, wherein said low-oxygen stream is directed into said intercooler for mixing with a compressed flow from said first-stage compressor section to produce a mixed flow that is directed to said second-stage compressor section. 
     
     
         14 . A turbine system in accordance with  claim 10 , wherein said low-NOx exhaust gas is directed to a HRSG for the generation of steam and a reduced temperature exhaust gas. 
     
     
         15 . A turbine system in accordance with  claim 14 , wherein said steam is directed to a bottoming cycle for the generation of additional electricity. 
     
     
         16 . A turbine system in accordance with  claim 14 , wherein said reduced temperature exhaust gas is split into a first portion that is directed to a carbon dioxide capture system and a second portion that is directed to said compressor for compression along with said air. 
     
     
         17 . A turbine system comprising:
 a compressor for compressing air to generate a compressed flow;   an air separation unit for receiving and separating at least a portion of said compressed flow into oxygen and a low-oxygen stream;   a combustor for receiving and combusting at least a portion of said low-oxygen stream, a portion of said compressed flow and a fuel to generate a high temperature exhaust gas; and   a turbine for receiving and expanding said high temperature exhaust gas to generate electricity and a reduced temperature low-NOx exhaust gas.   
     
     
         18 . A turbine system in accordance with  claim 17 , further comprising a mixer for receiving and mixing said compressed flow and said low-oxygen stream prior to introduction into said combustor. 
     
     
         19 . A gasification system comprising:
 an air separation unit for separating air into oxygen and a low-oxygen stream;   a gasifier for reacting said oxygen and a carbonaceous feedstock to produce a syngas;   a syngas processing system for converting said syngas to a purified combustible fuel; and   a gas turbine system comprising:
 a compressor for compressing air to generate a compressed flow; 
 a combustor for receiving and combusting at least a portion of said low-oxygen stream, at least a portion of said compressed flow and at least a portion of said purified combustible fuel to generate a high temperature exhaust gas; and 
 a turbine for receiving and expanding said high temperature exhaust gas to generate electricity and a reduced temperature low-NOx exhaust gas. 
   
     
     
         20 . A gasification system in accordance with  claim 19 , wherein said compressor comprises at least a first-stage compressor section and a second-stage compressor section. 
     
     
         21 . A gasification system in accordance with  claim 20 , wherein said low-oxygen stream is directed into said second-stage compressor section for mixing with a compressed flow from said first-stage compressor section. 
     
     
         22 . A gasification system in accordance with  claim 20 , further comprising an intercooler, wherein said low-oxygen stream is directed into said intercooler for mixing with a compressed flow from said first-stage compressor section to produce a mixed flow that is directed to said second-stage compressor section. 
     
     
         23 . A gasification system in accordance with  claim 19 , wherein said low-oxygen stream has less than about 20% by volume of oxygen. 
     
     
         24 . A gasification system in accordance with  claim 19 , wherein said low-oxygen stream has less than about 15% by volume of oxygen. 
     
     
         25 . A gasification system in accordance with  claim 19 , wherein said low-NOx exhaust gas has a NOx level of less than about 30 ppm. 
     
     
         26 . A gasification system in accordance with  claim 19 , wherein said low-NOx exhaust gas has a NOx level of less than about 10 ppm. 
     
     
         27 . A gasification system in accordance with  claim 19 , wherein said low-NOx exhaust gas is directed to a HRSG for the generation of steam and a reduced temperature exhaust gas. 
     
     
         28 . A gasification system in accordance with  claim 27 , wherein said steam is directed to a bottoming cycle for the generation of additional electricity. 
     
     
         29 . A gasification system in accordance with  claim 27 , wherein said reduced temperature exhaust gas is split into a first portion that is directed to a carbon dioxide capture system and a second portion that is directed to said compressor for compression along with said air. 
     
     
         30 . A gasification system comprising:
 an air separation unit for separating air into oxygen and a low-oxygen stream;   a gasifier for reacting said oxygen and a carbonaceous feedstock to produce a syngas;   a syngas processing system for converting said syngas to a purified combustible fuel; and   a gas turbine system comprising:
 a compressor for compressing air and at least a portion of said low-oxygen stream to generate a compressed flow; 
 a combustor for receiving and combusting said compressed flow and at least a portion of said purified combustible fuel to generate a high temperature exhaust gas; and 
 a turbine for receiving and expanding said high temperature exhaust gas to generate electricity and a reduced temperature low-NOx exhaust gas. 
   
     
     
         31 . A method of reducing emissions comprising the steps of:
 producing a low-oxygen stream;   producing a compressed air stream;   combusting at least a portion of said low-oxygen stream, a portion of said compressed air stream, and a fuel to produce a high temperature exhaust gas;   expanding said high temperature exhaust gas to generate electricity and a low-NOx exhaust gas.   
     
     
         32 . A method of reducing emissions in accordance with  claim 31 , further comprising the steps of:
 utilizing said low-NOx exhaust gas to generate steam and a reduced temperature exhaust gas.   
     
     
         33 . A method of reducing emissions in accordance with  claim 32 , further comprising the steps of:
 directing a first portion of said reduced temperature exhaust gas to a carbon dioxide removal system; and   compressing and mixing a second portion of said reduced temperature exhaust gas with said air stream to produce a low-oxygen compressed flow.