Co2 separation & liquefaction system and method

Abstract

A CO2 separation and liquefaction system such as might be used in a carbon capture and sequestration system for a fossil fuel burning power plant is disclosed. The CO2 separation and liquefaction system includes a first cooling stage to cool flue gas with liquid CO2, a compression stage coupled to the first cooling stage to compress the cooled flue gas, a second cooling stage coupled to the compression stage and the first cooling stage to cool the compressed flue gas with a CO2 melt and provide the liquid CO2 to the first cooling stage, and an expansion stage coupled to the second cooling stage to extract solid CO2 from the flue gas that melts in the second cooling stage to provide the liquid CO2.

1 . A method of providing a multi-stage recuperative cooling CO 2  extraction system comprising:
 receiving a first gas stream, the first gas stream containing CO 2 ;   splitting the first gas stream into a second gas stream and a third gas stream;   within a first stage of recuperative cooling, cooling the second gas stream, in an arrangement of one or more N 2  coolers that use a fourth gas stream, to form a cooled second gas stream, the fourth gas stream comprising recuperated CO 2 -depleted gas;   within a second stage of recuperative cooling, cooling the third gas stream, in an arrangement of one or more CO 2  coolers that use a first stream of CO 2 , to form a cooled third gas stream;   combining the cooled second gas stream and the cooled third gas stream to form a cooled fifth gas stream, the cooled fifth gas stream containing CO 2 ;   within a third stage of recuperative cooling, further cooling the cooled fifth gas stream, using a second stream of CO 2  to form a further cooled sixth gas stream comprising CO 2  and CO 2  that is provided to the first stream of CO 2 ;   within a fourth stage of recuperative cooling, cooling the further-cooled sixth gas stream, using one or more CO 2  frosting cooling steps, to a temperature sufficient to desublimate at least a portion of the gaseous CO 2  as solid CO 2  frost within the CO 2  frosting devices and the fourth gas stream.   
     
     
         2 . The method of  claim 1 , further comprising converting the solid CO 2  frost to liquid CO 2  using liquid CO 2.    
     
     
         3 . The method of  claim 1 , wherein the first and second streams of CO 2  are provided by a liquid CO 2  reservoir comprising extracted CO 2 . 
     
     
         4 . The method of  claim 1 , wherein the step of cooling the fifth gas stream is performed in an arrangement of one or more cooling stages. 
     
     
         5 . The method of  claim 4 , wherein the one or more cooling stages comprises one or more cold compressors and/or heat exchangers. 
     
     
         6 . The method of  claim 5 , wherein the one or more cooling stages comprises at least two stages, each of the at least two stages comprising a compression stage and a heat exchange stage. 
     
     
         7 . The method of  claim 1 , wherein the one or more CO 2  frosting cooling stages comprises one or more heat exchangers and/or expanders. 
     
     
         8 . The method of  claim 7 , further comprising changing the temperature of the fourth gas stream recuperatively from the sixth gas stream using a frost heat exchanger in the one or more CO 2  frosting cooling stages. 
     
     
         9 . The method of  claim 1 , further comprising:
 prior to splitting the first gas stream into the second gas stream and the third gas stream, pre-cooling the first gas stream.   
     
     
         10 . The method of  claim 9 , wherein the pre-cooling the first gas stream is performed using one or more external coolers and/or heat exchangers. 
     
     
         11 . The method of  claim 1 , further comprising:
 prior to the step of cooling the further-cooled sixth gas stream, adjusting the temperature of the sixth gas stream to a temperature higher than a temperature at which CO 2  desublimates.   
     
     
         12 . The method of  claim 1 , wherein the first gas stream is received from a source of flue gas. 
     
     
         13 . The method of  claim 12 , wherein the flue gas is received from a power plant. 
     
     
         14 . The method of  claim 13 , wherein the power plant is a natural gas power plant or a coal-fired steam plant. 
     
     
         15 . A CO 2  separation and liquefaction system for processing a gas containing CO 2 , the system comprising:
 a splitter configured and arranged to receive a first gas stream, the first gas stream containing CO 2 , and to split the first gas stream into a second gas stream and a third gas stream;   an arrangement of one or more N 2  coolers disposed downstream from the splitter and configured to cool the second gas stream, using a fourth gas stream, to form a cooled second gas stream, the fourth gas stream comprising recuperated CO 2 -depleted gas;   an arrangement of one or more recuperative coolers, disposed downstream from the splitter and configured to cool the third gas stream, using a first stream of CO 2 , to form a cooled third gas stream, wherein the arrangement of one or more CO 2  coolers is arranged in parallel with the arrangement of one or more N 2  coolers;   a mixer disposed downstream from the arrangement of one or more N 2  coolers and the arrangement of one or more CO 2  coolers and configured to combine the cooled second gas stream and the cooled third gas stream to form a fifth gas stream, the fifth gas stream containing CO 2 ;   an arrangement of one or more cold compressor cooling stages disposed downstream from the mixer and configured to cool the fifth gas stream, using a second stream of CO 2  from a liquid CO 2  reservoir, to form a sixth gas stream and CO 2  that is provided to the first stream of CO 2 ; and   an arrangement of one or more CO 2  frosting cooling stages disposed downstream from the one or more cold compressor cooling stages and configured to cool the sixth gas stream to a temperature sufficient to produce solid CO 2  frost and the fourth gas stream.   
     
     
         16 . The system of  claim 15 , further comprising a liquid CO 2  reservoir comprising CO 2  extracted from the gas containing CO 2  and other CO 2 -containing gases, wherein the first and second streams of CO 2  are provided by the liquid CO 2  reservoir. 
     
     
         17 . The system of  claim 15 , wherein the arrangement of one or more cooling stages disposed downstream from the mixer and configured to cool the fifth gas stream comprises one or more cold compressors and/or heat exchangers. 
     
     
         18 . The system of  claim 17 , wherein the one or more cooling stages comprises at least two stages, each of the at least two stages comprising a compression stage and a heat exchange stage. 
     
     
         19 . The system of  claim 15 , wherein the one or more CO 2  frosting cooling stages comprises one or more heat exchangers and/or expanders. 
     
     
         20 . The system of  claim 15 , further comprising a pre-cooling stage disposed upstream from the splitter and configured to cool the first gas stream. 
     
     
         21 . The system of  claim 15 , wherein the arrangement of one or more CO 2  frosting cooling stages uses the fourth gas stream to cool the sixth gas stream to the temperature sufficient to produce solid CO 2  frost.