Purification of carbon dioxide
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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Abstract
In a process for separating at least one “heavy” impurity such as hydrogen sulfide from crude carbon dioxide comprising significant quantities of at least one “light” impurity such as non-condensable gases, involving at least one heat pump cycle using carbon dioxide-containing fluid from the process as the working fluid, the “light” impurity is removed from the crude carbon dioxide and carbon dioxide is subsequently recovered from the removed “light” impurity, thereby improving overall carbon dioxide recovery and efficiency in terms of energy consumption.
14 Citations
34 Claims
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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; andwherein said recovered carbon dioxide is fed to said second column system for mass transfer separation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
- light”
Specification