Retrofit for power generation system

Abstract

A method of retrofitting a power generation system includes modifying a pre-existing power generation system that includes a combustor and a steam-based cycle to include a super-critical carbon dioxide-based Brayton cycle that is directly coupled through the combustor. The steam-based cycle is converted into a steam-based Rankine cycle that is in thermal-receiving communication with the super-critical carbon dioxide-based Brayton cycle.

What is claimed is: 
     
         1 . A method of retrofitting a power generation system, the method comprising:
 in a pre-existing power generation system including a combustor and a steam-based cycle, modifying the pre-existing power generation system to include a super-critical carbon dioxide-based Brayton cycle that is directly coupled through the combustor; and   converting the steam-based cycle into a steam-based Rankine cycle that is in thermal-receiving communication with the super-critical carbon dioxide-based Brayton cycle.   
     
     
         2 . The method as recited in  claim 1 , wherein:
 the super-critical carbon dioxide-based Brayton cycle includes at least one turbine and the steam-based cycle includes at least one turbine, and   mounting the at least one turbine of the super-critical carbon dioxide-based Brayton cycle and the at least one turbine of the steam-based cycle on a common shaft to drive a generator.   
     
     
         3 . The method as recited in  claim 1 , wherein the modifying includes providing superalloy tubes that extend through the combustor. 
     
     
         4 . The method as recited in  claim 3 , including locating the superalloy tubes through a first portion of the combustor that is hotter than a second, different portion of the combustor through which tubes of the steam-based cycle extended prior to the modification. 
     
     
         5 . The method as recited in  claim 1 , wherein the converting includes removing tubes of the steam-based cycle from the combustor. 
     
     
         6 . The method as recited in  claim 1 , wherein the converting includes connecting a heat exchanger in communication with the super-critical carbon dioxide-based Brayton cycle and the steam-based Rankine cycle. 
     
     
         7 . The method as recited in  claim 1 , wherein the combustor is a fluidized-bed reactor. 
     
     
         8 . The method as recited in  claim 7 , including thermally coupling the super-critical carbon dioxide-based Brayton cycle directly through the fluidized-bed reactor. 
     
     
         9 . A method of retrofitting a power generation system, the method comprising:
 providing a pre-existing power generation system comprising a combustor and a steam-based cycle, the steam-based cycle including a first working fluid circuit extending through the combustor and at least one turbine in fluid communication with the first working fluid circuit, the at least one turbine being mounted on a shaft that is coupled to drive a generator, the first working fluid circuit and the at least one turbine defining a first maximum operating temperature;   replacing the first working fluid circuit with a second working fluid circuit extending through the combustor; and   adding at least one additional turbine mounted on the shaft, the at least one additional turbine being in fluid communication with the second working fluid circuit and the at least one turbine, the second working fluid circuit and the at least one additional turbine defining a second maximum operating temperature that is greater than the first maximum operating temperature.   
     
     
         10 . The method as recited in  claim 9 , wherein the adding of the at least one additional turbine includes arranging the at least one additional turbine upstream of the at least one turbine such that the at least one turbine is in flow-receiving communication with the at least one additional turbine. 
     
     
         11 . The method as recited in  claim 9 , wherein the first working fluid circuit includes steel tubes and the second working fluid circuit includes superalloy tubes. 
     
     
         12 . The method as recited in  claim 9 , wherein the at least one additional turbine includes superalloy blades. 
     
     
         13 . A retro-fitted power generation system comprising:
 a combustor;   a working fluid circuit extending through the combustor;   at least one pre-existing turbine having a first maximum operating temperature;   at least one retrofit turbine arranged in fluid communication with the working fluid circuit and the at least one pre-existing turbine, the at least one retrofit turbine having a second, greater maximum operating temperature.   
     
     
         14 . The system as recited in  claim 13 , wherein the combustor is selected from the group consisting of a coal-fired boiler and a fluidized bed reactor. 
     
     
         15 . The system as recited in  claim 13 , wherein the working fluid circuit includes superalloy tubes extending through the combustor. 
     
     
         16 . The system as recited in  claim 13 , wherein the at least one pre-existing turbine includes steel and the retrofit turbine includes a superalloy material. 
     
     
         17 . The system as recited in  claim 13 , wherein the at least one pre-existing turbine and the retrofit turbine are mounted on a common shaft. 
     
     
         18 . The system as recited in  claim 13 , wherein the at least one retrofit turbine is arranged upstream of the at least one pre-existing turbine such that the at least one pre-existing turbine is in flow-receiving communication with the at least one retrofit turbine.