Utilization of low grade heat in a refrigeration cycle

Abstract

A system for reducing the power required to cool a combustion gas for cleaning and a method for performing the same are disclosed. The system includes an expander for producing power. Energy in the form of heat is transferred from the combustion gas to a working fluid. The working fluid drives the expander to generate at least a portion of the power required for performing to drive a compressor in a refrigeration system. After the combustion gas transfers energy the combustion gas is cooled with the refrigeration system. In some embodiments the expander and the compressor are arranged along a common shaft.

1 . A system for generating power from a heat source, the system comprising:
 a heat source;   a first working fluid;   a heat exchanger arranged relative to the heat source for transferring energy between the heat source and the first working fluid;   an expander for generating power, the expander in fluid communication with the heat exchanger;   wherein the first working fluid flows from the heat exchanger to the expander after the first working fluid receives energy from the heat source;   wherein the first working fluid drives the expander to generate power for operating a compressor.   
     
     
         2 . The system of  claim 1 , wherein the compressor is part of a refrigeration system for cooling a combustion gas. 
     
     
         3 . The system of  claim 2 , wherein the expander generates a least a portion of the power required to perform the Chilled Ammonia Process. 
     
     
         4 . The system of  claim 2 , wherein the combustion gas is the heat source. 
     
     
         5 . The system of  claim 4 , wherein the combustion gas transfers energy to the first working fluid in the heat exchanger before the refrigeration system cools the combustion gas. 
     
     
         6 . The system of  claim 2 , wherein the expander and the compressor are arranged to form a coupled compressor-expander assembly. 
     
     
         7 . The system of  claim 6 , wherein the compressor-expander assembly is arranged along a common shaft. 
     
     
         8 . The system of  claim 7 , further comprising a second working fluid for driving the compressor. 
     
     
         9 . The system of  claim 8 , further comprising a condenser, the condenser being in fluid communication with the expander and the compressor,
 wherein the expander and condenser are arranged so that first working fluid flows into the condenser after exiting the expander;   wherein the compressor and the condenser are arranged so that the second working fluid flows into the condenser after existing the compressor.   
     
     
         10 . The system of  claim 9 , wherein the first working fluid and the second working fluid are the same. 
     
     
         11 . The system of  claim 1 , wherein the heat source is one or more of a combustion gas, CO 2  compressor intercooling, Wet Flue Gas Desulfurization (WFGD) hydrocyclone overflow, or heat from a Direct Contact Condenser. 
     
     
         12 . A method for generating power from a heat source, the method comprising the steps of:
 providing a heat source;   providing a first working fluid;   transferring energy from the heat source to the first working fluid using a heat exchanger;   providing an expander for generating power, the expander being in fluid communication with the heat exchanger;   driving the expander with the first working fluid to generate power;   operating a compressor with power generated by the expander.   
     
     
         13 . The method of  claim 12 , further including the step of:
 cooling the combustion gas with a refrigeration system;   wherein the compressor is a component of the refrigeration system.   
     
     
         14 . The method of  claim 13 , further comprising the step of:
 performing the Chilled Ammonia process on the combustion gas, wherein the expander generates a least a portion of the energy required to perform the Chilled Ammonia Process.   
     
     
         15 . The method of  claim 13 , wherein the heat source comprises the combustion gas. 
     
     
         16 . The method of  claim 15 , wherein the step of transferring energy from the combustion gas to the first working fluid occurs before the combustion gas is cooled with the refrigeration system. 
     
     
         17 . The method of  claim 13 , wherein the expander and the compressor are arranged to form a coupled compressor-expander assembly. 
     
     
         18 . The method of  claim 17 , wherein the compressor-expander assembly is arranged along a common shaft. 
     
     
         19 . The method of  claim 18 , further comprising the step of:
 providing a second working fluid for driving the compressor.   
     
     
         20 . The method of  claim 19 , further comprising the step of:
 providing a condenser, the condenser being in fluid communication with the expander and the compressor,   wherein the first working fluid flows into the condenser after exiting the expander;   wherein the second working fluid flows into the condenser after existing the compressor.   
     
     
         21 . The method of  claim 20 , wherein the first working fluid and the second working fluid are the same. 
     
     
         22 . The method of  claim 12 , wherein the heat source is one or more of a combustion gas, CO 2  compressor intercooling, Wet Flue Gas Desulfurization (WFGD) hydrocyclone overflow, or heat from a Direct Contact Condenser.