Purification of carbon dioxide

  • US 10,254,042 B2
  • Filed: 10/25/2013
  • Issued: 04/09/2019
  • Est. Priority Date: 10/25/2013
  • Status: Active Grant
First Claim
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1. A process for purifying crude carbon dioxide fluid comprising at least one “

  • light”

    impurity and at least one “

    heavy”

    impurity, said process comprising;

    cooling said crude carbon dioxide fluid above the triple point pressure of carbon dioxide by indirect heat exchange to produce a cooled crude carbon dioxide fluid;

    feeding said cooled crude carbon dioxide fluid to a first column system for mass transfer separation to produce a “

    light”

    impurity-enriched overhead vapor and a “

    light”

    impurity-depleted carbon dioxide bottoms liquid comprising said “

    heavy”

    impurity;

    re-boiling said first column system by vaporizing a portion of said “

    light”

    impurity-depleted carbon dioxide bottoms liquid by indirect heat exchange to provide a vapor for said first column system;

    feeding a further portion of said “

    light”

    impurity-depleted carbon dioxide bottoms liquid from said first column system to a second column system for mass transfer separation to produce a carbon dioxide-enriched overhead vapor and a “

    heavy”

    impurity-enriched bottoms liquid;

    providing a carbon dioxide-enriched liquid as reflux for said second column system;

    re-boiling said second column system by indirect heat exchange to provide a vapor for said second column system;

    wherein said first and second column systems operate above the triple point pressure and below the critical pressure of carbon dioxide;

    wherein said process comprises at least one heat pump cycle using as working fluid a portion of said carbon dioxide-enriched overhead vapor from said second column system;

    wherein said second column system is re-boiled by at least partially vaporizing a portion of said “

    heavy”

    impurity-enriched liquid in or taken from said second column system by indirect heat exchange against said working fluid of said at least one heat pump cycle;

    wherein said overhead vapor from said first column system comprises carbon dioxide and at least a portion of said carbon dioxide is recovered from said overhead vapor from said first column system to produce a “

    light”

    impurity-rich residual gas and a recovered carbon dioxide; and

    wherein said recovered carbon dioxide is fed to said second column system for mass transfer separation.

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