Carbon Dioxide Recovery

Abstract

The present techniques are directed to a system and method for recovering carbon dioxide (CO 2 ). The method includes recovering the CO 2 from a gas mixture including the CO 2 via a CO 2 separation system. The CO 2 separation system includes a rotating freezer/melter.

What is claimed is: 
     
         1 . A system for recovering carbon dioxide (CO 2 ), comprising a CO 2  separation system configured to recover the CO 2  from a gas mixture, wherein the CO 2  separation system comprises a rotating freezer/melter. 
     
     
         2 . The system of  claim 1 , wherein the rotating freezer/melter comprises a freezing zone, a melting zone, and a rotor. 
     
     
         3 . The system of  claim 2 , wherein solid CO 2  formed from the CO 2  within the gas mixture is captured on the rotor within the freezing zone, and wherein the gas mixture passes through the rotor within the freezing zone. 
     
     
         4 . The system of  claim 3 , wherein the solid CO 2  is formed from the CO 2  within the gas mixture via a heat exchanger and an expander upstream of the rotating freezer/melter. 
     
     
         5 . The system of  claim 3 , wherein the solid CO 2  melts and passes through the rotor as liquid CO 2  within the melting zone. 
     
     
         6 . The system of  claim 5 , wherein a portion of the liquid CO 2  is recycled to the melting zone of the rotating freezer/melter and used to melt the solid CO 2  within the melting zone. 
     
     
         7 . The system of  claim 3 , wherein the CO 2  separation system comprises a CO 2  separation device downstream of the freezing zone of the rotating freezer/melter, and wherein the CO 2  separation device recovers residual CO 2  from the gas mixture. 
     
     
         8 . The system of  claim 7 , wherein the CO 2  separation device recovers the residual CO 2  from the gas mixture via an amine separation process. 
     
     
         9 . The system of  claim 7 , wherein the CO 2  separation device recovers the residual CO 2  from the gas mixture via a potassium carbonate separation process. 
     
     
         10 . The system of  claim 7 , wherein the residual CO 2  recovered via the CO 2  separation device is pressurized via a compressor to produce a pressurized CO 2  vapor stream, and wherein the pressurized CO 2  vapor stream is used to melt the solid CO 2  within the melting zone of the rotating freezer/melter. 
     
     
         11 . The system of  claim 1 , comprising a power plant configured to generate power, wherein an exhaust gas from the power plant provides the gas mixture, and wherein the gas mixture comprises the CO 2 , H 2 O, and inert gas. 
     
     
         12 . The system of  claim 11 , comprising a dehydration system configured to remove the H 2 O from the gas mixture. 
     
     
         13 . The system of  claim 11 , wherein the power plant comprises:
 an expander turbine configured to provide mechanical energy by extracting energy from the gas mixture after combustion of the gas mixture in a combustor; and   a generator configured to generate electricity from the mechanical energy provided by the expander turbine.   
     
     
         14 . The system of  claim 11 , wherein the power plant comprises a combined cycle power plant. 
     
     
         15 . The system of  claim 14 , wherein the combined cycle power plant comprises:
 an expander turbine configured to provide mechanical energy by extracting energy from the gas mixture after combustion of the gas mixture in a combustor;   a heat recovery steam generator (HRSG) configured to generate steam by heating a boiler with an exhaust stream from the expander turbine;   a steam turbine configured to provide mechanical energy by extracting energy from the steam generated by the HRSG; and   a generator configured to generate electricity from the mechanical energy provided by the expander turbine and the steam turbine.   
     
     
         16 . The system of  claim 11 , wherein a portion of the gas mixture is recycled to the power plant. 
     
     
         17 . The system of  claim 1 , wherein the gas mixture comprises a natural gas stream comprising the CO 2 . 
     
     
         18 . A method for recovering carbon dioxide (CO 2 ), comprising recovering the CO 2  from a gas mixture comprising the CO 2  via a CO 2  separation system, wherein the CO 2  separation system comprises a rotating freezer/melter. 
     
     
         19 . The method of  claim 18 , wherein recovering the CO 2  from the gas mixture via a CO 2  separation system comprises:
 capturing solid CO 2  formed from the gas mixture on a rotor of the rotating freezer/melter while the rotor is in a freezing zone of the rotating freezer/melter;   flowing the gas mixture through the rotor while the rotor is in the freezing zone; melting the solid CO 2  that is captured on the rotor to form liquid CO 2  while the rotor is in a melting zone of the rotating freezer/melter; and   flowing the liquid CO 2  through the rotor while the rotor is in the melting zone.   
     
     
         20 . The method of  claim 19 , comprising forming the solid CO 2  from the CO 2  within the gas mixture using a heat exchanger and an expander upstream of the rotating freezer/melter. 
     
     
         21 . The method of  claim 19 , comprising:
 recycling a portion of the liquid CO 2  to the melting zone of the rotating freezer/melter; and   using the portion of the liquid CO 2  to melt the solid CO 2  within the melting zone.   
     
     
         22 . The method of  claim 19 , comprising:
 recovering residual CO 2  from the gas mixture via a CO 2  separation device downstream of the freezing zone of the rotating freezer/melter;   pressurizing the recovered residual CO 2  via a compressor to produce a pressurized CO 2  vapor stream; and   using the pressurized CO 2  vapor stream to melt the solid CO 2  within the melting zone of the rotating freezer/melter.   
     
     
         23 . The method of  claim 18 , comprising producing power via a power plant, wherein an exhaust gas from the power plant provides the gas mixture, and wherein the gas mixture comprises the CO 2 , H 2 O, and inert gas. 
     
     
         24 . The method of  claim 23 , comprising removing the H 2 O from the gas mixture via a dehydration system. 
     
     
         25 . The method of  claim 23 , wherein producing the power via the power plant comprises:
 providing mechanical energy via an expander turbine using energy extracted from the gas mixture after combustion of the gas mixture in a combustor; and   generating electricity via a generator using the mechanical energy provided by the expander turbine.   
     
     
         26 . The method of  claim 23 , wherein producing the power via the power plant comprises:
 providing mechanical energy via an expander turbine using energy extracted from the gas mixture after combustion of the gas mixture in a combustor;   generating steam via a heat recovery steam generator (HRSG) by heating a boiler with an exhaust stream from the expander turbine;   providing mechanical energy via a steam turbine using energy extracted from the steam generated by the HRSG; and   generating electricity via a generator using the mechanical energy provided by the expander turbine and the steam turbine.   
     
     
         27 . A rotating freezer/melter for recovering carbon dioxide (CO 2 ) from a gas mixture, comprising:
 a freezing zone;   a melting zone; and   a rotor configured to rotate through the freezing zone and the melting zone;   wherein solid CO 2  formed from a gas mixture is captured on the rotor while the rotor is rotating through the freezing zone, and wherein the solid CO 2  melts and flows through the rotor as liquid CO 2  while the rotor is rotating through the melting zone.   
     
     
         28 . The rotating freezer/melter of  claim 27 , wherein the rotor comprises porous ceramic. 
     
     
         29 . The rotating freezer/melter of  claim 27 , wherein the rotor comprises a plurality of layers of metal mesh screens. 
     
     
         30 . The rotating freezer/melter of  claim 27 , comprising a sealing device for individually sealing both the freezing zone and the melting zone of the rotating freezer/melter. 
     
     
         31 . The rotating freezer/melter of  claim 27 , wherein gaseous components within the gas mixture flow through the rotor while the rotor is rotating through the freezing zone.