System for cooling exhaust gas with absorption chiller

Abstract

A gas turbine system includes a gas turbine engine configured to combust a fuel and produce an exhaust gas. An exhaust duct assembly is coupled to the gas turbine engine and is configured to receive the exhaust gas. An absorption chiller is fluidly coupled to the exhaust duct assembly and is configured to receive a take-off stream of the exhaust gas. The absorption chiller is configured to use the take-off stream to drive at least a portion of an absorption cooling process to generate a cooled take-off stream of exhaust gas. The exhaust duct assembly is configured to receive the cooled take-off stream of exhaust gas from the absorption chiller and to mix the cooled take-off stream with exhaust gas present within the exhaust duct assembly to cool the exhaust gas.

The invention claimed is: 
     
       1. A gas turbine system, comprising: a gas turbine engine configured to combust a fuel and produce an exhaust gas; an exhaust duct assembly fluidly coupled to the gas turbine engine and configured to receive the exhaust gas from the gas turbine engine;
 an absorption chiller fluidly coupled to the exhaust duct assembly and configured to receive a take-off stream of exhaust gas from the exhaust duct assembly via an exhaust take-off path, wherein the absorption chiller is configured to use the take-off stream of exhaust gas to drive at least a portion of an absorption cooling process to generate a cooled take-off stream of exhaust gas; and 
 wherein the exhaust duct assembly is configured to receive the cooled take-off stream of exhaust gas from the absorption chiller via a cooled take-off path and to mix the cooled take-off stream of exhaust gas with exhaust gas present within the exhaust duct assembly to cool the exhaust gas, and 
 a heat exchanger disposed within a tempering air injection system fluidly coupled to the exhaust duct assembly, wherein the heat exchanger is configured to receive a chilled fluid from the absorption chiller via a chilled fluid path and to direct a return fluid generated from the chilled fluid to the absorption chiller via a return fluid path, wherein the chilled fluid path extends from a chilled fluid outlet of the absorption chiller to a chilled fluid inlet of the heat exchanger, and the return fluid path extends from a return fluid outlet of the heat exchanger to a return fluid inlet of the absorption chiller, and wherein the chilled fluid path and the return fluid path are fluidly coupled. 
 
     
     
       2. The gas turbine system of  claim 1 , wherein the exhaust duct assembly comprises an absorption cooling inlet and an absorption cooling outlet, wherein the exhaust take-off path extends from the absorption cooling inlet to the absorption chiller, and wherein the cooled take-off path extends from the absorption chiller to the absorption cooling outlet. 
     
     
       3. The gas turbine system of  claim 2 , wherein the absorption chiller comprises a generator section having a generator heat exchanger, wherein the generator heat exchanger is configured to place the take-off stream of exhaust gas in heat exchange with a dilute absorber solution to produce the cooled take-off stream of exhaust gas and a concentrated absorber solution. 
     
     
       4. The gas turbine system of  claim 1 , comprising a selective catalytic reduction (SCR) catalyst disposed within the exhaust duct assembly and configured to reduce NO x  present within the exhaust gas. 
     
     
       5. The gas turbine system of  claim 4 , comprising an ammonia skid having a source of ammonia and one or more flow paths configured to direct ammonia to an ammonia injection grid positioned within the exhaust duct assembly upstream of the SCR catalyst. 
     
     
       6. The gas turbine system of  claim 1 , wherein the tempering air injection system is configured to inject tempering air generated via heat exchange between the chilled fluid and air into an exhaust gas flow path of the exhaust duct assembly to cool the exhaust gas. 
     
     
       7. The gas turbine system of  claim 6 , wherein the tempering air injection system is configured to inject the tempering air via a tempering air injection grid positioned along the exhaust gas flow path. 
     
     
       8. The gas turbine system of  claim 7 , wherein the tempering air injection grid is positioned upstream of a selective catalytic reduction (SCR) catalyst configured to reduce NO x  present within the exhaust gas. 
     
     
       9. The gas turbine system of  claim 6 , comprising a control system communicatively coupled to one or more flow control devices of the tempering air injection system and to one or more sensors configured to enable the control system to monitor a parameter of the exhaust gas within the exhaust duct assembly, wherein the control system is configured to adjust an amount of the tempering air used to cool the exhaust gas in response to detecting a change in the monitored parameter of the exhaust gas. 
     
     
       10. The gas turbine system of  claim 6 , comprising a control system communicatively coupled to one or more flow control devices of the tempering air injection system, wherein the control system is configured to monitor loading of the gas turbine engine, and to adjust an amount of the tempering air used to cool the exhaust gas in response to detecting a change in the loading of the gas turbine engine or ambient air conditions. 
     
     
       11. The gas turbine system of  claim 2 , comprising a tempering air injection grid disposed within the exhaust duct assembly, wherein the absorption cooling inlet and the absorption cooling outlet are disposed upstream of the tempering air injection grid. 
     
     
       12. A system, comprising:
 an exhaust duct assembly configured to receive exhaust gas from a gas turbine engine; 
 an absorption chiller fluidly coupled to the exhaust duct assembly and configured to receive a take-off stream of exhaust gas from the exhaust duct assembly via an exhaust take-off path, wherein the absorption chiller is configured to use the take-off stream of exhaust gas to drive at least a portion of an absorption cooling process to generate a cooled take-off stream of exhaust gas; and 
 a tempering air injection system fluidly coupled to the exhaust duct assembly and configured to provide tempering air to the exhaust duct assembly, wherein the tempering air injection system comprises a heat exchanger fluidly coupled to the absorption chiller, wherein the absorption chiller is configured to flow a stream of chilled fluid to the heat exchanger via a chilled fluid path extending between a chilled fluid outlet of the heat exchanger and a chilled fluid inlet of the absorption chiller, and wherein the heat exchanger is configured to direct a return fluid flow generated from the chilled fluid to the absorption chiller via a return flow path extending between a return fluid outlet of the heat exchanger and a return fluid inlet of the absorption chiller, wherein the chilled fluid path and the return fluid path are fluidly coupled. 
 
     
     
       13. The system of  claim 12 , wherein the absorption chiller comprises a generator section having a generator heat exchanger, wherein the generator heat exchanger is fluidly coupled to the exhaust duct assembly by a take-off flow path such that the generator heat exchanger is configured to receive the take-off stream of exhaust gas and place the take-off stream of exhaust gas in heat exchange with a dilute absorber solution to produce the cooled take-off stream of exhaust gas and a concentrated absorber solution. 
     
     
       14. The system of  claim 12 , comprising a flow control system positioned along the chilled fluid path and configured to split the stream of chilled fluid between the heat exchanger and an exhaust gas heat exchanger positioned within the exhaust duct assembly. 
     
     
       15. The system of  claim 14 , comprising a control system communicatively coupled to at least a portion of the flow control system, wherein the control system is configured to control the split of the stream of chilled fluid to control an amount of the stream of chilled fluid provided to the heat exchanger versus an amount of the stream of chilled fluid provided to the exhaust gas heat exchanger. 
     
     
       16. The system of  claim 15 , wherein the control system is configured to control the split based on loading of the gas turbine engine, based on ambient air conditions, based on a sensed temperature of exhaust gas within the exhaust duct assembly, or any combination thereof. 
     
     
       17. The gas turbine system of  claim 12 , comprising a cooled take-off path extending between the absorption chiller and an absorption cooling outlet disposed along the exhaust duct assembly, wherein the cooled take-of path is fluidly coupled to the exhaust take-off path, wherein the exhaust take-off path extends between an absorption cooling inlet and the absorption chiller, and wherein the absorption cooling inlet and the absorption cooling outlet are disposed adjacent to an upstream end of the exhaust duct assembly. 
     
     
       18. A gas turbine system, comprising:
 a gas turbine engine configured to combust a fuel and produce an exhaust gas; 
 an exhaust duct assembly fluidly coupled to the gas turbine engine and configured to receive the exhaust gas from the gas turbine engine, wherein the exhaust duct assembly is configured to flow the exhaust gas along an exhaust gas path from an inlet to an outlet; 
 a selective catalytic reduction (SCR) system having an SCR catalyst positioned within the exhaust duct assembly and an ammonia injection grid positioned within the exhaust duct assembly upstream of the SCR catalyst, wherein the ammonia injection grid is configured to inject ammonia into the exhaust gas path and the SCR catalyst is configured to reduce an amount of NOx present within the exhaust gas; 
 an absorption chiller fluidly coupled to the exhaust duct assembly and configured to receive a take-off stream of exhaust gas from the exhaust duct assembly via an exhaust take-off path, wherein the absorption chiller is configured to use the take-off stream of exhaust gas to drive at least a portion of an absorption cooling process to generate a cooled take-off stream of exhaust gas, wherein the exhaust duct assembly is configured to receive the cooled take-off stream of exhaust gas from the absorption chiller via a cooled take-off path and to mix the cooled take-off stream of exhaust gas with exhaust gas along the exhaust gas path to cool the exhaust gas; 
 a tempering air injection system fluidly coupled to the exhaust duct assembly and the absorption chiller and comprising a heat exchanger configured to receive a chilled fluid from the absorption chiller and to cool a stream of air within the tempering air injection system via heat exchange with the chilled fluid to generate a tempering air and a return fluid; 
 a chilled fluid path extending from a chilled fluid outlet of the absorption chiller to a chilled fluid inlet of the heat exchanger, wherein the chilled fluid path is configured to direct the chilled fluid from the absorption chiller to the heat exchanger; 
 a return fluid path fluidly coupled to the chilled fluid path and extending from a return fluid outlet of the heat exchanger and a return fluid inlet of the absorption chiller, wherein the return fluid path is configured to direct the return fluid from the heat exchanger to the absorption chiller, and wherein the chilled fluid path and the return fluid path are fluidly coupled; and 
 a control system configured to control cooling of the exhaust gas along the exhaust gas path such that a temperature of the exhaust gas, upon encountering the SCR catalyst, is within a predetermined temperature range that is appropriate for the SCR catalyst to reduce the amount of NOx present within the exhaust gas. 
 
     
     
       19. The gas turbine system of  claim 18 , wherein the tempering air injection system is configured to provide the tempering air to the exhaust duct assembly, and wherein the control system is configured to control cooling of the exhaust gas by controlling at least a flow of the stream of chilled fluid to the heat exchanger and to control a flow of the take-off stream to the absorption chiller. 
     
     
       20. The gas turbine system of  claim 18 , wherein the exhaust take-off path extends from an absorption cooling inlet disposed along the exhaust duct assembly to the absorption chiller, and the cooled take-off path extends from the absorption chiller to an absorption cooling outlet disposed along the exhaust duct assembly, wherein the exhaust take-off path and the cooled take-off path are fluidly coupled, and wherein the absorption cooling inlet and the absorption cooling outlet are disposed between the tempering air injection system and the ammonia injection grid.