Distillative separation of methane and carbon dioxide
First Claim
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1. A method of distillatively separating a feed stream containing methane and carbon dioxide into an overhead product enriched in methane and a bottoms product enriched in carbon dioxide, comprising:
- a. introducing said feed stream into a distillation column;
b. providing sufficient heat to the bottom of said distillation column to provide a bottoms product enriched in carbon dioxide;
c. withdrawing an overhead stream from the top of said column;
d. condensing at least a portion of said overhead stream for reflux in an overhead condenser at a temperature above the triple point of carbon dioxide and directing said condensed portion of overhead back to said column as reflux, said condensed portion being sufficient to provide a column overhead enriched in methane;
e. introducing a non-polar agent miscible with methane directly into the said overhead condenser of said distillation column in a quantity sufficient to maintain the temperature in the said condenser and at all locations within the distillation column above the triple point of carbon dioxide;
f. withdrawing that portion of the overhead stream not employed as reflux as overhead product enriched in methane; and
,g. withdrawing a bottoms product enriched in carbon dioxide.
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Abstract
An improvement in a Ryan/Holmes separation of methane from carbon dioxide is disclosed wherein the upper portion of a distillation column is operated, i.e., -70° F., while still effectuating a separation of methane from carbon dioxide. This is achieved by increasing the amount of nonpolar liquid agent added to the condenser of the column to an amount sufficient to maintain the condenser and all portions of the column above such temperatures.
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Citations
21 Claims
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1. A method of distillatively separating a feed stream containing methane and carbon dioxide into an overhead product enriched in methane and a bottoms product enriched in carbon dioxide, comprising:
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a. introducing said feed stream into a distillation column; b. providing sufficient heat to the bottom of said distillation column to provide a bottoms product enriched in carbon dioxide; c. withdrawing an overhead stream from the top of said column; d. condensing at least a portion of said overhead stream for reflux in an overhead condenser at a temperature above the triple point of carbon dioxide and directing said condensed portion of overhead back to said column as reflux, said condensed portion being sufficient to provide a column overhead enriched in methane; e. introducing a non-polar agent miscible with methane directly into the said overhead condenser of said distillation column in a quantity sufficient to maintain the temperature in the said condenser and at all locations within the distillation column above the triple point of carbon dioxide; f. withdrawing that portion of the overhead stream not employed as reflux as overhead product enriched in methane; and
,g. withdrawing a bottoms product enriched in carbon dioxide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. In a distillative separation wherein a feed stream containing methane and carbon dioxide is introduced into a distillation column and separated therein into an overhead product enriched in methane and a bottoms product enriched in carbon dioxide including withdrawing an overhead stream, condensing at least a portion thereof in a condenser, and directing said condensed portion back to the upper portion of said distillation column as reflux to the distillation column;
- the improvement wherein the temperature is maintained in said overhead condenser and at all points in said distillation column at a temperature above about -70°
F. by the introduction directly into the overhead condenser of said distillation column of a non-polar liquid agent miscible with the methane, the liquid non-polar agent introduced in an amount of from about 0.01 to 2.0 moles of non-polar agent per mole of methane in the feed stream and the overhead stream containing less than about 15 mole % of carbon dioxide. - View Dependent Claims (18, 19, 20, 21)
- the improvement wherein the temperature is maintained in said overhead condenser and at all points in said distillation column at a temperature above about -70°
Specification