Apparatus for reducing emissions and method of assembly

Abstract

A heat recovery steam generator (HRSG) is coupled to a gas turbine engine that is configured to combust a fuel in air to produce shaft power and a flow of exhaust gases including oxides of nitrogen (NO x ). The HRSG includes at least one duct burner for heating the exhaust gases and at least one NOx reduction element coupled downstream from the at least one duct burner and configured to facilitate reducing an amount of NOx in the exhaust gases that are channeled into the at least one NOx reduction element.

1 . A method of providing a heat recovery steam generator (HRSG) for use with a gas turbine engine, said method comprising:
 coupling at least one duct burner within the HRSG; and   coupling at least one oxides of nitrogen (NO x ) reduction element downstream from the at least one duct burner, wherein the at least one duct burner is configured to operate during gas turbine engine operations including startup, shutdown, and low-load operations with insufficient exhaust temperatures at the NO catalyst inlet for desired NO x  reduction to increase a temperature of exhaust gases routed through the at least one NO x  reduction element to enable the at least one NO x  reduction element to facilitate NO x  reduction reactions during the gas turbine engine operations.   
     
     
         2 . A method in accordance with  claim 1 , further comprising coupling an injection apparatus downstream from the at least one duct burner and upstream from the at least one NO x  reduction element, wherein the injection apparatus is configured to inject a reducing agent into the exhaust gases. 
     
     
         3 . A method in accordance with  claim 1 , further comprising coupling the at least one duct burner to a controller that is configured to selectively activate the at least one duct burner based on a temperature of the exhaust gases upstream from the at least one duct burner 
     
     
         4 . A method in accordance with  claim 3 , wherein coupling the at least one duct burner to a controller further comprises configuring the controller to activate the at least one duct burner to heat the exhaust gases during the gas turbine startup. 
     
     
         5 . A method in accordance with  claim 1 , wherein the at least one duct burner includes a plurality of fuel circuits, said method further comprising coupling the plurality of fuel circuits to at least one fuel source. 
     
     
         6 . A heat recovery steam generator (HRSG) coupled to a gas turbine engine that discharges a flow of exhaust gases including oxides of nitrogen (NO x ), said HRSG comprising:
 at least one duct burner for heating the exhaust gases; and   at least one NO x  reduction element coupled downstream from said at least one duct burner and configured to facilitate reducing an amount of NO x  in the exhaust gases that are channeled into said at least one NO x  reduction element.   
     
     
         7 . An HRSG in accordance with  claim 6 , wherein said at least one duct burner is configured to be selectively activated based on a temperature of the exhaust gases upstream from said at least one duct burner. 
     
     
         8 . An HRSG in accordance with  claim 6 , wherein said at least one duct burner is configured to heat the exhaust gases to a temperature above approximately 500 degrees Fahrenheit. 
     
     
         9 . An HRSG in accordance with  claim 6 , wherein said at least one duct burner is configured to heat the exhaust gases during any of a startup phase, a shut down phase, and a load condition with insufficient exhaust temperatures at the NO x  catalyst inlet for desired NO x  reduction. 
     
     
         10 . An HRSG in accordance with  claim 6 , wherein said duct burner comprises a plurality of fuel circuits. 
     
     
         11 . An HRSG in accordance with  claim 6 , further comprising an injection apparatus coupled downstream from said at least one duct burner and upstream from said at least one NO x  reduction element, wherein said injection apparatus is configured to inject a reducing agent into the exhaust gases to facilitate NO x  reduction reactions. 
     
     
         12 . An HRSG in accordance with  claim 6 , wherein the flow of exhaust gases also includes carbon monoxide (CO), said HRSG further comprising a CO oxidation catalyst element coupled downstream from said at least one duct burner and upstream from said injection apparatus. 
     
     
         13 . An HRSG in accordance with  claim 6 , further comprising:
 a first heat exchanger coupled upstream from said at least one duct burner; and   at least a second duct burner coupled upstream from said first heat exchanger.   
     
     
         14 . An HRSG in accordance with  claim 13 , further comprising a second heat exchanger coupled downstream from said at least one NO x  reduction element. 
     
     
         15 . A combined cycle power plant comprising:
 a gas turbine engine configured to combust a fuel in air to produce shaft power and a flow of exhaust gases including oxides of nitrogen (NO x ); and   a heat recovery steam generator (HRSG) coupled in flow communication with said gas turbine engine, said HRSG comprising:
 at least one duct burner for heating the exhaust gases; and 
 at least one NO x  reduction element coupled downstream from said at least one duct burner and configured to facilitate reducing an amount of NO x  in the exhaust gases channeled into said at least one NO x  reduction. 
   
     
     
         16 . A combined cycle power plant in accordance with  claim 15 , wherein said at least one duct burner is configured to be selectively activated based on a temperature of the exhaust gases upstream from said at least one duct burner. 
     
     
         17 . A combined cycle power plant in accordance with  claim 15 , wherein said at least one duct burner is configured to heat the exhaust gases to a temperature above approximately 500 degrees Fahrenheit or above a catalyst light off temperature. 
     
     
         18 . A combined cycle power plant in accordance with  claim 15 , wherein said at least one duct burner is configured to heat the exhaust gases during a transient operation phase of said combined cycle power plant. 
     
     
         19 . A combined cycle power plant in accordance with  claim 15 , wherein said at least one duct burner comprises a plurality of fuel circuits. 
     
     
         20 . A combined cycle power plant in accordance with  claim 15 , wherein said HRSG further comprises an injection apparatus coupled downstream from said at least one duct burner and upstream from said at least one NO x  reduction element, wherein said injection apparatus is configured to inject a reducing agent into the exhaust gases to facilitate NO x  reduction reactions.