Reduction of co and o2 emissions in oxyfuel hydrocarbon combustion systems using oh radical formation with hydrogen fuel staging and diluent addition

Abstract

A method for reducing the amount of carbon monoxide and oxygen emissions in an oxyfuel hydrocarbon combustion system, comprising the steps of feeding defined amounts of hydrocarbon fuel and an oxidizer (e.g., air) to one or more combustors in the engine and igniting the mixture to form a first combustor exhaust stream; determining the amount of carbon monoxide present at the head end of a combustor in the initial combustor exhaust stream; identifying one or more target locations within the combustor at a point downstream from the first exhaust stream for injecting free hydrogen and a supplemental oxidizer; injecting hydrogen and the supplemental oxidizer into the combustor at specified downstream locations based on the amount of detected carbon monoxide; and injecting a diluent (e.g., CO 2 ) into the combustor at a point further downstream in the combustor exhaust to control the exhaust temperature.

1 . A method for reducing the amount of emissions in an oxyfuel hydrocarbon combustion system, comprising:
 (a) feeding hydrocarbon fuel and an oxidizer to one or more combustors in said combustion system;   (b) igniting the mixture of said hydrocarbon fuel and said oxidizer to form a first combustor exhaust stream;   (c) detecting the amount of carbon monoxide present at the head end of said combustor in said first combustor exhaust stream;   (d) identifying one or more target locations within said combustor at a point downstream from said first combustor exhaust stream for injecting hydrogen and a supplemental oxidizer; and   (e) injecting hydrogen and said supplemental oxidizer into said combustor at said downstream point based on said detected amount of carbon monoxide.   
     
     
         2 . A method according to  claim 1 , further comprising the step of injecting a diluent into said combustor at a point further downstream of said first combustor exhaust stream. 
     
     
         3 . A method according to  claim 2 , further comprising the step of controlling the temperature of the exhaust stream at the point of injection of said diluent. 
     
     
         4 . A method according to  claim 1 , wherein said emissions comprise carbon monoxide and oxygen. 
     
     
         5 . A method according to  claim 2 , wherein said diluent comprises carbon dioxide. 
     
     
         6 . A method according to  claim 1 , wherein said step of feeding defined amounts of said hydrocarbon fuel and said supplemental oxidizer to one or more combustors results in a Phi value greater than 1.0. 
     
     
         7 . A method according to  claim 1 , wherein the amount of said hydrogen injected into said combustor is about 1/10 the mass of the original hydrocarbon fuel feed. 
     
     
         8 . A method according to  claim 1 , wherein said oxyfuel hydrocarbon combustion system comprises multiple combustors. 
     
     
         9 . A method according to  claim 1 , wherein, said diluent is injected into said combustor in an amount sufficient to preclude the further formation of carbon monoxide following said hydrogen injection. 
     
     
         10 . A method according to  claim 1 , wherein said steps of injecting said hydrogen and said supplemental oxidizer result in an amount of OH radical being formed sufficient to reduce the amount of CO through a reaction with said supplemental oxidizer to form CO 2 . 
     
     
         11 . A method according to  claim 1 , wherein said oxidizer comprises air. 
     
     
         12 . A method according to  claim 1 , wherein said injections of hydrogen, supplemental oxidizer and diluent are made according to the following relative time periods: hydrogen 2X; supplemental oxidizer 5X; and diluent 6X, wherein X is the injection time period in milliseconds. 
     
     
         13 . A method according to  claim 1 , wherein the duration, amount and frequency of said injections of hydrogen, supplemental oxidizer and diluent control the OH radical formation immediately downstream of the combustor head. 
     
     
         14 . A gas turbine engine, comprising:
 a gas compressor;   a plurality of combustors;   a turbine driven by the expanded exhaust from said combustors;   a primary fuel circuit for said combustors, said fuel circuit including means for feeding hydrocarbon fuel and air to each combustor;   a supplemental fuel circuit for one or more of said combustors, said supplemental fuel circuit including a plurality of hydrogen injection nozzles for feeding additional hydrogen into said combustors;   one or more injection ports for feeding a supplemental oxidizer into one or more of said combustors; and   a feedback control loop for controlling the amount of additional hydrogen and supplemental oxidizer feeds necessary to reduce the amount of carbon monoxide and oxygen present in the gas turbine exhaust.   
     
     
         15 . A gas turbine engine according to  claim 14 , further comprising means for injecting diluent into the exhaust stream of said combustors to control the temperature of said exhaust stream. 
     
     
         16 . A gas turbine engine according to  claim 14 , wherein said feedback control loop comprises one or more carbon monoxide sensors disposed in the exhaust stream of said combustors. 
     
     
         17 . A gas turbine engine according to  claim 14 , wherein said feedback control loop comprises one or more OH radical detectors disposed in the exhaust stream of said combustors. 
     
     
         18 . A gas turbine engine according to  claim 14 , wherein said hydrogen injection nozzles feed an amount of hydrogen equal to about 1/10 the mass of said hydrocarbon fuel being fed to said combustors. 
     
     
         19 . A gas turbine engine according to  claim 14 , wherein said gas turbine engine further comprises means for injecting a diluent into said plurality of combustors. 
     
     
         20 . A gas turbine engine according to  claim 19  wherein said diluent comprises CO 2 .