US 2011/0296867 A1 · Hydrocarbon Gas Processing

Abstract

A process and an apparatus are disclosed for removing carbon dioxide from a hydrocarbon gas stream. The gas stream is cooled, expanded to intermediate pressure, and supplied to a fractionation tower at a top column feed position. The tower overhead vapor stream is compressed to higher pressure and cooled to partially condense it, forming a condensed stream. The condensed stream is expanded to intermediate pressure, used to subcool a portion of the tower bottom liquid product, then supplied to the tower at a mid-column feed position. The subcooled portion of the tower bottom liquid product is expanded to lower pressure and used to cool the compressed overhead vapor stream. The quantities and temperatures of the feeds to the fractionation tower are effective to maintain the overhead temperature of the fractionation tower at a temperature whereby the major portion of the carbon dioxide is recovered in the tower bottom liquid product.

Claims6

Dependent claims

A process for the separation of a gas stream containing at least methane and carbon dioxide into a volatile residue gas fraction containing a major portion of said methane and a relatively less volatile fraction containing a major portion of said carbon dioxide wherein

(1) said gas stream is cooled, thereby forming a cooled stream;
(2) said cooled stream is expanded to intermediate pressure whereby it is further cooled;
(3) said expanded cooled stream is supplied as a top feed to a distillation column and fractionated at said intermediate pressure into an overhead vapor stream and said relatively less volatile fraction;
(4) said overhead vapor stream is compressed to higher pressure;
(5) said compressed overhead vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a residual vapor stream and a condensed stream;
(6) said condensed stream is expanded to said intermediate pressure and heated, and thereafter supplied to said distillation column at a mid-column feed position;
(7) said relatively less volatile fraction is divided into at least first and second streams;
(8) said second stream is cooled, thereby to supply at least a portion of the heating of step (6);
(9) said cooled second stream is expanded to lower pressure whereby it is further cooled;
(10) said expanded cooled second stream is heated, thereby to supply at least a portion of the cooling of step (5);
(11) said residual vapor stream is heated, thereby to supply at least a portion of the cooling of steps (1) and (5), and thereafter discharging said heated residual vapor stream as said volatile residue gas fraction;
and
(12) the quantities and temperatures of said feed streams to said distillation column are effective to maintain the overhead temperature of said distillation column at a temperature whereby the major portion of said carbon dioxide is recovered in said relatively less volatile fraction.

10 more elements

(1) said gas stream is cooled sufficiently to partially condense it;
(2) said partially condensed gas stream is separated, thereby to provide a vapor stream and at least one liquid stream;
(3) said vapor stream is expanded to intermediate pressure;
(4) said expanded vapor stream is supplied as a top feed to a distillation column and fractionated at said intermediate pressure into an overhead vapor stream and said relatively less volatile fraction;
(5) said at least one liquid stream is expanded to said intermediate pressure, and thereafter supplied to said distillation column at an upper mid-column feed position;
(6) said overhead vapor stream is compressed to higher pressure;
(7) said compressed overhead vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a residual vapor stream and a condensed stream;
(8) said condensed stream is expanded to said intermediate pressure and heated, and thereafter supplied to said distillation column at a lower mid-column feed position below said upper mid-column feed position;
(9) said relatively less volatile fraction is divided into at least first and second streams;
(10) said second stream is cooled, thereby to supply at least a portion of the heating of step (8);
(11) said cooled second stream is expanded to lower pressure whereby it is further cooled;
(12) said expanded cooled second stream is heated, thereby to supply at least a portion of the cooling of step (7);
(13) said residual vapor stream is heated, thereby to supply at least a portion of the cooling of steps (1) and (7), and thereafter discharging said heated residual vapor stream as said volatile residue gas fraction;
and
(14) the quantities and temperatures of said feed streams to said distillation column are effective to maintain the overhead temperature of said distillation column at a temperature whereby the major portion of said carbon dioxide is recovered in said relatively less volatile fraction.

12 more elements

An apparatus for the separation of a gas stream containing at least methane and carbon dioxide into a volatile residue gas fraction containing a major portion of said methane and a relatively less volatile fraction containing a major portion of said carbon dioxide comprising

(1) first heat exchange means to cool said gas stream, thereby forming a cooled stream;
(2) first expansion means connected to said first heat exchange means to receive said cooled stream and expand it to intermediate pressure;
(3) distillation column connected to said first expansion means to receive said expanded cooled stream as a top feed thereto, said distillation column being adapted to fractionate said expanded cooled stream at said intermediate pressure into an overhead vapor stream and said relatively less volatile fraction;
(4) compressing means connected to said distillation column to receive said overhead vapor stream and compress it to higher pressure;
(5) second heat exchange means connected to said compressing means to receive said compressed overhead vapor stream and cool it sufficiently to condense at least a part of it;
(6) separating means connected to said second heat exchange means to receive said partially condensed compressed overhead vapor stream and separate it, thereby forming a residual vapor stream and a condensed stream;
(7) second expansion means connected to said separating means to receive said condensed stream and expand it to said intermediate pressure;
(8) third heat exchange means connected to said second expansion means to receive said expanded condensed stream and heat it, said third heat exchange means being further connected to said distillation column to supply said heated expanded condensed stream to said distillation column at a mid-column feed position;
(9) dividing means connected to said distillation column to receive said relatively less volatile fraction and divide it into at least first and second streams;
(10) said third heat exchange means being further connected to said dividing means to receive said second stream and cool it, thereby to supply at least a portion of the heating of step (8);
(11) third expansion means connected to said third heat exchange means to receive said cooled second stream and expand it to lower pressure;
(12) said second heat exchange means being further connected to said third expansion means to receive said expanded cooled second stream and heat it, thereby to supply at least a portion of the cooling of step (5);
(13) said second heat exchange means being further connected to said separating means to receive said residual vapor stream and heat it, thereby to supply at least a portion of the cooling of step (5);
(14) said first heat exchange means being further connected to said second heat exchange means to receive said heated residual vapor stream and further heat it, thereby to supply at least a portion of the cooling of step (1), and thereafter discharging said further heated residual vapor stream as said volatile residue gas fraction;
and
(15) control means adapted to regulate the quantities and temperatures of said feed streams to said distillation column to maintain the overhead temperature of said distillation column at a temperature whereby the major portion of said carbon dioxide is recovered in said relatively less volatile fraction.

13 more elements

(1) first heat exchange means to cool said gas stream sufficiently to partially condense it, thereby forming a partially condensed gas stream;
(2) first separating means connected to said first heat exchange means to receive said partially condensed gas stream and separate it into a vapor stream and at least one liquid stream;
(3) first expansion means connected to said first separating means to receive said vapor stream and expand it to intermediate pressure;
(4) distillation column connected to said first expansion means to receive said expanded vapor stream as a top feed thereto, said distillation column being adapted to fractionate said expanded vapor stream at said intermediate pressure into an overhead vapor stream and said relatively less volatile fraction;
(5) second expansion means connected to said first separating means to receive said at least one liquid stream and expand it to said intermediate pressure, said second expansion means being further connected to said distillation column to supply said expanded at least one liquid stream to said distillation column at an upper mid-column feed position;
(6) compressing means connected to said distillation column to receive said overhead vapor stream and compress it to higher pressure;
(7) second heat exchange means connected to said compressing means to receive said compressed overhead vapor stream and cool it sufficiently to condense at least a part of it;
(8) second separating means connected to said second heat exchange means to receive said partially condensed compressed overhead vapor stream and separate it, thereby forming a residual vapor stream and a condensed stream;
(9) third expansion means connected to said second separating means to receive said condensed stream and expand it to said intermediate pressure;
(10) third heat exchange means connected to said third expansion means to receive said expanded condensed stream and heat it, said third heat exchange means being further connected to said distillation column to supply said heated expanded condensed stream to said distillation column at a lower mid-column feed position below said upper mid-column feed position;
(11) dividing means connected to said distillation column to receive said relatively less volatile fraction and divide it into at least first and second streams;
(12) said third heat exchange means being further connected to said dividing means to receive said second stream and cool it, thereby to supply at least a portion of the heating of step (10);
(13) fourth expansion means connected to said third heat exchange means to receive said cooled second stream and expand it to lower pressure;
(14) said second heat exchange means being further connected to said fourth expansion means to receive said expanded cooled second stream and heat it, thereby to supply at least a portion of the cooling of step (7);
(15) said second heat exchange means being further connected to said second separating means to receive said residual vapor stream and heat it, thereby to supply at least a portion of the cooling of step (7);
(16) said first heat exchange means being further connected to said second heat exchange means to receive said heated residual vapor stream and further heat it, thereby to supply at least a portion of the cooling of step (1), and thereafter discharging said further heated residual vapor stream as said volatile residue gas fraction;
and
(17) control means adapted to regulate the quantities and temperatures of said feed streams to said distillation column to maintain the overhead temperature of said distillation column at a temperature whereby the major portion of said carbon dioxide is recovered in said relatively less volatile fraction.

15 more elements

Dependencies are inferred from the claim text.

Hydrocarbon Gas Processing

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Hydrocarbon Gas Processing

Life of this patent

Abstract

Claims6