Process for throttling a compressed gas for evaporative cooling

Abstract

A system and method of cooling a compressed working fluid is disclosed. The method includes compressing the working fluid above its critical pressure point in a compression stage to generate a compressed working fluid at or about local ambient temperature. The compressed working fluid can be cooled to below ambient by throttling a portion of the compressed working fluid to its saturated liquid-vapor state to generate a recycle working fluid. The recycle working fluid may then be atomized using an atomizing nozzle whereby the recycle working fluid evaporates and cools working fluid entering a target compression stage.

1 . A system for cooling a compressed working fluid, comprising:
 a compressor having a series of compression stages for compressing a working fluid, the series of compression stages including an evaporative compression stage and a target compression stage, wherein the evaporative compression stage compresses the working fluid to at least a critical pressure;   a series of heat exchangers fluidly coupled to the series of compression stages such that at least one heat exchanger interposes adjacent compression stages, the series of heat exchangers being configured to decrease a temperature of the working fluid discharged from a preceding compression stage;   a valve fluidly coupled to a heat exchanger following the evaporative compression stage, the valve being configured to throttle a portion of the working fluid to at least its saturated liquid-vapor state; and   a fogging device fluidly coupled to the valve and the target compression stage, the fogging device being configured to evaporate the portion of the working fluid to evaporatively cool the working fluid entering the target compression stage.   
     
     
         2 . The system of  claim 1 , wherein the compressor is a centrifugal compressor. 
     
     
         3 . The system of  claim 1 , wherein the working fluid is carbon dioxide. 
     
     
         4 . The system of  claim 1 , wherein the series of heat exchangers are water-cooled or air-cooled heat exchangers. 
     
     
         5 . The system of  claim 1 , wherein the series of heat exchangers are configured to reduce the temperature of the working fluid to at or near ambient temperature. 
     
     
         6 . The system of  claim 1 , wherein the valve further throttles the portion of the working fluid to at or near a suction pressure of the target compression stage. 
     
     
         7 . The system of  claim 1 , wherein the fogging device has an atomizing nozzle that atomizes the portion of the working fluid in the presence of the working fluid. 
     
     
         8 . The system of  claim 7 , wherein the fogging device reduces the temperature of the working fluid to below ambient temperature. 
     
     
         9 . The system of  claim 1 , wherein the evaporative compression stage and the target compression stage are the same compression stage. 
     
     
         10 . A method of cooling a compressed working fluid, comprising:
 compressing a working fluid in a series of compression stages, the series of compression stages including an evaporative compression stage and a target compression stage;   cooling the working fluid in a series of heat exchangers fluidly coupled to the series of compression stages, wherein at least one heat exchanger is interposed between each compression stage and each heat exchanger is configured to decrease a temperature of the working fluid discharged from a preceding compression stage;   compressing the working fluid to at least a critical pressure in the evaporative compression stage;   throttling a portion of the working fluid discharged from the evaporative compression stage with a valve fluidly coupled to the evaporative compression stage, the portion of the working fluid being throttled to at least its saturated liquid-vapor state; and   atomizing the portion of the working fluid with a fogging device fluidly coupled to the valve and the target compression stage, whereby the portion of the working fluid evaporates and cools the working fluid entering the target compression stage.   
     
     
         11 . The method of  claim 10 , wherein cooling the working fluid in a series of heat exchangers further comprises cooling the working fluid discharged from a preceding compression stage to at or near ambient temperature. 
     
     
         12 . The method of  claim 10 , further comprising throttling the portion of the working fluid to at or near a suction pressure of the target compression stage. 
     
     
         13 . The method of  claim 10 , wherein the fogging device comprises an atomizing nozzle. 
     
     
         14 . The method of  claim 13 , further comprising atomizing the portion of the working fluid with the atomizing nozzle. 
     
     
         15 . The method of  claim 10 , further comprising evaporatively cooling the working fluid entering the target compression stage to below ambient temperature. 
     
     
         16 . A method of cooling a working fluid in a compressor, comprising:
 compressing the working fluid above a critical pressure in a first compression stage to generate a compressed working fluid;   throttling a portion of the compressed working fluid to its saturated liquid-vapor state to generate a recycle working fluid;   atomizing the recycle working fluid with an atomizing nozzle whereby the recycle working fluid evaporates and cools; and   injecting the recycle working fluid at a suction inlet of a target compression stage to cool the working fluid therein.   
     
     
         17 . The method of  claim 16 , wherein the working fluid is carbon dioxide. 
     
     
         18 . The method of  claim 16 , further comprising throttling the portion of the compressed working fluid to at or near a suction pressure of the second compression stage. 
     
     
         19 . The method of  claim 16 , wherein the target compression stage is the first compression stage. 
     
     
         20 . The method of  claim 16 , further comprising cooling the working fluid entering the second compression stage to below ambient temperature. 
     
     
         21 - 37 . (canceled)