Hydrocarbon gas processing

• US 8,590,340 B2
• Filed: 01/09/2008
• Issued: 11/26/2013
• Est. Priority Date: 02/09/2007
• Status: Active Grant

• Current Assignee: UOP Llc (Honeywell International Inc.)
• Original Assignee: Ortloff Enigneers, Ltd.
• Inventors: Pitman, Richard N., Wilkinson, John D., Lynch, Joe T., Hudson, Hank M., Martinez, Tony L.
• Primary Examiner(s): Huynh, Khoa
• Assistant Examiner(s): Trieu, Timothy K
• Application Number:
  US11/971,491
• Publication Number:
  US 20080190136A1
• Time in Patent Office: 2,148 Days
• Field of Search: 626/21, 626/11, 626/43, 951/84
• US Class Current: 62/621
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/30 using a side column in a single pressure column system
• CPC Class Codes: F25J 2200/76 Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
• CPC Class Codes: F25J 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2230/08 Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler
• CPC Class Codes: F25J 2230/60 the fluid being hydrocarbons or a mixture of hydrocarbons
• CPC Class Codes: F25J 2235/60 the fluid being (a mixture of) hydrocarbons
• CPC Class Codes: F25J 2240/02 Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2245/02 Recycle of a stream in general, e.g. a by-pass stream
• CPC Class Codes: F25J 2290/40 Vertical layout or arrangement of cold equipments within in the cold box, e.g. columns, condensers, heat exchangers etc.
• CPC Class Codes: F25J 3/0209 Natural gas or substitute natural gas
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0238 separation of CnHm with 2 carbon atoms or more
• CPC Class Codes: F25J 3/0242 separation of CnHm with 3 carbon atoms or more

Abstract

A process and apparatus for the recovery of ethane, ethylene, propane, propylene, and heavier hydrocarbon components from a hydrocarbon gas stream is disclosed. The stream is cooled and divided into first and second streams. The first stream is further cooled to condense substantially all of it and is thereafter expanded to the pressure of a fractionation tower and supplied to the fractionation tower at a first mid-column feed position. The second stream is expanded to the tower pressure and is then supplied to the column at a second mid-column feed position. A distillation vapor stream is withdrawn from the column below the feed point of the first stream and compressed to an intermediate pressure, and is then directed into heat exchange relation with the tower overhead vapor stream to cool the distillation stream and condense substantially all of it, forming a condensed stream. At least a portion of the condensed stream is directed to the fractionation tower at a third mid-column feed position located above the feed point of the first stream. A recycle stream is withdrawn from the tower overhead after it has been warmed and compressed. The compressed recycle stream is cooled sufficiently to substantially condense it, and is then expanded to the pressure of the fractionation tower and supplied to the tower at a top column feed position. 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 desired components is recovered.

Claims

1. In a process for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is cooled under pressure to provide a cooled stream;

(b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and

(c) said further cooled stream is directed into a distillation column and fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered;

the improvement wherein following cooling, said cooled stream is divided into first and second streams; and

(1) said first stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled;

(2) said expanded cooled first stream is thereafter supplied to said distillation column at a first mid-column feed position;

(3) said second stream is expanded to said lower pressure and is supplied to said distillation column at a second mid-column feed position;

(4) a distillation vapor stream is withdrawn from a region of said distillation column below said expanded cooled first stream and is compressed to an intermediate pressure;

(5) said compressed distillation vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a condensed stream;

(6) at least a portion of said condensed stream is expanded to said lower pressure and is thereafter supplied to said distillation column at a third mid-column feed position located above said expanded cooled first stream;

(7) an overhead vapor stream is withdrawn from an upper region of said distillation column and at least a portion of said overhead vapor stream is directed into heat exchange relation with said compressed distillation vapor stream and heated, thereby to supply at least a portion of the cooling of step (5);

(8) said heated overhead vapor stream is compressed to higher pressure and thereafter divided into said volatile residue gas fraction and a compressed recycle stream;

(9) said compressed recycle stream is cooled sufficiently to substantially condense it;

(10) said substantially condensed compressed recycle stream is expanded to said lower pressure and supplied to said distillation column at a top feed position; and

(11) 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 portions of the components in said relatively less volatile fraction are recovered.

4. The improvement according to claim 1, 2, or 3 wherein

(1) said overhead vapor stream is divided into at least a first vapor stream and a second vapor stream;

(2) said first vapor stream is combined with said distillation vapor stream to form a combined vapor stream, whereupon said combined vapor stream is compressed to said intermediate pressure;

(3) said compressed combined vapor stream is cooled sufficiently to condense at least a part of it, thereby forming said condensed stream;

(4) said second vapor stream is directed into heat exchange relation with said compressed combined stream and heated, thereby to supply at least a portion of the cooling of step (3); and

(5) said heated second vapor stream is compressed to said higher pressure and thereafter divided into said volatile residue gas fraction and said compressed recycle stream.

5. The improvement according to claim 4 wherein

(1) said condensed stream is divided into at least a first portion and a second portion;

(2) said first portion is expanded to said lower pressure and is thereafter supplied to said distillation column at said third mid-column feed position; and

(3) said second portion is expanded to said lower pressure and is thereafter supplied to said distillation column at a mid-column feed position below that of said expanded first portion.

6. The improvement according to claim 1, 2, or 3 wherein

(1) said condensed stream is divided into at least a first portion and a second portion;

(2) said first portion is expanded to said lower pressure and is thereafter supplied to said distillation column at said third mid-column feed position; and

(3) said second portion is expanded to said lower pressure and is thereafter supplied to said distillation column at a mid-column feed position below that of said expanded first portion.

7. The improvement according to claim 1, 2, or 3 wherein said at least a portion of said expanded condensed stream is combined with said expanded substantially condensed compressed recycle stream to form a combined condensed stream, whereupon said combined condensed stream is supplied to said distillation column at said top feed position.

2. In a process for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is cooled under pressure to provide a cooled stream;

(b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and

(c) said further cooled stream is directed into a distillation column and fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered;

the improvement wherein said gas stream is cooled sufficiently to partially condense it; and

(1) said partially condensed gas stream is separated thereby to provide a vapor stream and at least one liquid stream;

(2) said vapor stream is thereafter divided into first and second streams;

(3) said first stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled;

(4) said expanded cooled first stream is thereafter supplied to said distillation column at a first mid-column feed position;

(5) said second stream is expanded to said lower pressure and is supplied to said distillation column at a second mid-column feed position;

(6) a distillation vapor stream is withdrawn from a region of said distillation column below said expanded cooled first stream and is compressed to an intermediate pressure;

(7) said compressed distillation vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a condensed stream;

(8) at least a portion of said condensed stream is expanded to said lower pressure and is thereafter supplied to said distillation column at a third mid-column feed position located above said expanded cooled first stream;

(9) at least a portion of said at least one liquid stream is expanded to said lower pressure and is supplied to said distillation column at a fourth mid-column feed position;

(10) an overhead vapor stream is withdrawn from an upper region of said distillation column and at least a portion of said overhead vapor stream is directed into heat exchange relation with said compressed distillation vapor stream and heated, thereby to supply at least a portion of the cooling of step (7);

(11) said heated overhead vapor stream is compressed to higher pressure and thereafter divided into said volatile residue gas fraction and a compressed recycle stream;

(12) said compressed recycle stream is cooled sufficiently to substantially condense it;

(13) said substantially condensed compressed recycle stream is expanded to said lower pressure and supplied to said distillation column at a top feed position; 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 portions of the components in said relatively less volatile fraction are recovered.

3. In a process for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is cooled under pressure to provide a cooled stream;

(b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and

(c) said further cooled stream is directed into a distillation column and fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered;

the improvement wherein said gas stream is cooled sufficiently to partially condense it; and

(1) said partially condensed gas stream is separated thereby to provide a vapor stream and at least one liquid stream;

(2) said vapor stream is thereafter divided into first and second streams;

(3) said first stream is combined with at least a portion of said at least one liquid stream to form a combined stream, and said combined stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled;

(4) said expanded cooled combined stream is thereafter supplied to said distillation column at a first mid-column feed position;

(5) said second stream is expanded to said lower pressure and is supplied to said distillation column at a second mid-column feed position;

(6) a distillation vapor stream is withdrawn from a region of said distillation column below said expanded cooled combined stream and is compressed to an intermediate pressure;

(7) said compressed distillation vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a condensed stream;

(8) at least a portion of said condensed stream is expanded to said lower pressure and is thereafter supplied to said distillation column at a third mid-column feed position located above said expanded cooled combined stream;

(9) any remaining portion of said at least one liquid stream is expanded to said lower pressure and is supplied to said distillation column at a fourth mid-column feed position;

(10) an overhead vapor stream is withdrawn from an upper region of said distillation column and at least a portion of said overhead vapor stream is directed into heat exchange relation with said compressed distillation vapor stream and heated, thereby to supply at least a portion of the cooling of step (7);

(11) said heated overhead vapor stream is compressed to higher pressure and thereafter divided into said volatile residue gas fraction and a compressed recycle stream;

(12) said compressed recycle stream is cooled sufficiently to substantially condense it;

(13) said substantially condensed compressed recycle stream is expanded to said lower pressure and supplied to said distillation column at a top feed position; 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 portions of the components in said relatively less volatile fraction are recovered.

8. In a process for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is cooled under pressure to provide a cooled stream;

(b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and

(c) said further cooled stream is directed into a distillation column and fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered;

the improvement wherein following cooling, said cooled stream is divided into first and second streams; and

(1) said first stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled;

(2) said expanded cooled first stream is thereafter supplied at a first mid-column feed position to a contacting and separating device that produces a first overhead vapor stream and a bottom liquid stream, whereupon said bottom liquid stream is supplied to said distillation column;

(3) a second overhead vapor stream is withdrawn from an upper region of said distillation column and is directed to said contacting and separating device at a first lower feed position;

(4) said second stream is expanded to said lower pressure and is supplied to said contacting and separating device at a second lower feed position;

(5) a distillation vapor stream is withdrawn from a region of said contacting and separating device below said expanded cooled first stream and is compressed to an intermediate pressure;

(6) said compressed distillation vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a condensed stream;

(7) at least a portion of said condensed stream is expanded to said lower pressure and is thereafter supplied to said contacting and separating device at a second mid-column feed position located above said expanded cooled first stream;

(8) at least a portion of said first overhead vapor stream is directed into heat exchange relation with said compressed distillation vapor stream and heated, thereby to supply at least a portion of the cooling of step (6);

(9) said heated first overhead vapor stream is compressed to higher pressure and thereafter divided into said volatile residue gas fraction and a compressed recycle stream;

(10) said compressed recycle stream is cooled sufficiently to substantially condense it;

(11) said substantially condensed compressed recycle stream is expanded to said lower pressure and supplied to said contacting and separating device at a top feed position; and

(12) the quantities and temperatures of said feed streams to said contacting and separating device are effective to maintain the overhead temperature of said contacting and separating device at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered.

9. In a process for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is cooled under pressure to provide a cooled stream;

(b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and

(c) said further cooled stream is directed into a distillation column and fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered;

the improvement wherein said gas stream is cooled sufficiently to partially condense it; and

(1) said partially condensed gas stream is separated thereby to provide a vapor stream and at least one liquid stream;

(2) said vapor stream is thereafter divided into first and second streams;

(3) said first stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled;

(4) said expanded cooled first stream is thereafter supplied at a first mid-column feed position to a contacting and separating device that produces a first overhead vapor stream and a bottom liquid stream, whereupon said bottom liquid stream is supplied to said distillation column;

(5) a second overhead vapor stream is withdrawn from an upper region of said distillation column and is directed to said contacting and separating device at a first lower feed position;

(6) said second stream is expanded to said lower pressure and is supplied to said contacting and separating device at a second lower feed position;

(7) a distillation vapor stream is withdrawn from a region of said contacting and separating device below said expanded cooled first stream and is compressed to an intermediate pressure;

(8) said compressed distillation vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a condensed stream;

(9) at least a portion of said condensed stream is expanded to said lower pressure and is thereafter supplied to said contacting and separating device at a second mid-column feed position located above said expanded cooled first stream;

(10) at least a portion of said at least one liquid stream is expanded to said lower pressure and is supplied to said distillation column at a mid-column feed position;

(11) at least a portion of said first overhead vapor stream is directed into heat exchange relation with said compressed distillation vapor stream and heated, thereby to supply at least a portion of the cooling of step (8);

(12) said heated first overhead vapor stream is compressed to higher pressure and thereafter divided into said volatile residue gas fraction and a compressed recycle stream;

(13) said compressed recycle stream is cooled sufficiently to substantially condense it;

(14) said substantially condensed compressed recycle stream is expanded to said lower pressure and supplied to said contacting and separating device at a top feed position; and

(15) the quantities and temperatures of said feed streams to said contacting and separating device are effective to maintain the overhead temperature of said contacting and separating device at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered.

10. In a process for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is cooled under pressure to provide a cooled stream;

(b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and

(c) said further cooled stream is directed into a distillation column and fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered;

the improvement wherein said gas stream is cooled sufficiently to partially condense it; and

(1) said partially condensed gas stream is separated thereby to provide a vapor stream and at least one liquid stream;

(2) said vapor stream is thereafter divided into first and second streams;

(3) said first stream is combined with at least a portion of said at least one liquid stream to form a combined stream, and said combined stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled;

(4) said expanded cooled combined stream is thereafter supplied at a first mid-column feed position to a contacting and separating device that produces a first overhead vapor stream and a bottom liquid stream, whereupon said bottom liquid stream is supplied to said distillation column;

(5) a second overhead vapor stream is withdrawn from an upper region of said distillation column and is directed to said contacting and separating device at a first lower feed position;

(6) said second stream is expanded to said lower pressure and is supplied to said contacting and separating device at a second lower feed position;

(7) a distillation vapor stream is withdrawn from a region of said contacting and separating device below said expanded cooled combined stream and is compressed to an intermediate pressure;

(8) said compressed distillation vapor stream is cooled sufficiently to condense at least a part of it, thereby forming a condensed stream;

(9) at least a portion of said condensed stream is expanded to said lower pressure and is thereafter supplied to said contacting and separating device at a second mid-column feed position located above said expanded cooled combined stream;

(10) any remaining portion of said at least one liquid stream is expanded to said lower pressure and is supplied to said distillation column at a mid-column feed position;

(11) at least a portion of said first overhead vapor stream is directed into heat exchange relation with said compressed distillation vapor stream and heated, thereby to supply at least a portion of the cooling of step (8);

(12) said heated first overhead vapor stream is compressed to higher pressure and thereafter divided into said volatile residue gas fraction and a compressed recycle stream;

(13) said compressed recycle stream is cooled sufficiently to substantially condense it;

(14) said substantially condensed compressed recycle stream is expanded to said lower pressure and supplied to said contacting and separating device at a top feed position; and

(15) the quantities and temperatures of said feed streams to said contacting and separating device are effective to maintain the overhead temperature of said contacting and separating device at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered.

11. The improvement according to claim 8, 9, or 10 wherein

(1) said first overhead vapor stream is divided into at least a first vapor stream and a second vapor stream;

(2) said first vapor stream is combined with said distillation vapor stream to form a combined vapor stream, whereupon said combined vapor stream is compressed to said intermediate pressure;

(3) said compressed combined vapor stream is cooled sufficiently to condense at least a part of it, thereby forming said condensed stream;

(4) said second vapor stream is directed into heat exchange relation with said compressed combined stream and heated, thereby to supply at least a portion of the cooling of step (3); and

(5) said heated second vapor stream is compressed to said higher pressure and thereafter divided into said volatile residue gas fraction and said compressed recycle stream.

12. The improvement according to claim 11 wherein

(1) said condensed stream is divided into at least a first portion and a second portion;

(2) said first portion is expanded to said lower pressure and is thereafter supplied to said contacting and separating device at said second mid-column feed position; and

(3) said second portion is expanded to said lower pressure and is thereafter supplied to said contacting and separating device at a mid-column feed position below that of said expanded first portion.

13. The improvement according to claim 8, 9, or 10 wherein

(1) said condensed stream is divided into at least a first portion and a second portion;

(2) said first portion is expanded to said lower pressure and is thereafter supplied to said contacting and separating device at said second mid-column feed position; and

(3) said second portion is expanded to said lower pressure and is thereafter supplied to said contacting and separating device at a mid-column feed position below that of said expanded first portion.

14. The improvement according to claim 8, 9, or 10 wherein said at least a portion of said expanded condensed stream is combined with said expanded substantially condensed compressed recycle stream to form a combined condensed stream, whereupon said combined condensed stream is supplied to said contacting and separating device at said top feed position.

15. In an apparatus for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in said apparatus there being

(a) a first cooling means to cool said gas under pressure connected to provide a cooled stream under pressure;

(b) a first expansion means connected to receive at least a portion of said cooled stream under pressure and to expand it to a lower pressure, whereby said stream is further cooled; and

(c) a distillation column connected to receive said further cooled stream, said distillation column being adapted to separate said further cooled stream into an overhead vapor stream and said relatively less volatile fraction;

the improvement wherein said apparatus includes

(1) first dividing means connected to said first cooling means to receive said cooled stream and to divide it into first and second streams;

(2) second cooling means connected to said first dividing means to receive said first stream and to cool it sufficiently to substantially condense it;

(3) said first expansion means being connected to said second cooling means to receive said substantially condensed first stream and to expand it to said lower pressure, said first expansion means being further connected to said distillation column to supply said expanded cooled first stream to said distillation column at a first mid-column feed position;

(4) second expansion means connected to said first dividing means to receive said second stream and to expand it to said lower pressure, said second expansion means being further connected to said distillation column to supply said expanded second stream to said distillation column at a second mid-column feed position;

(5) vapor withdrawing means connected to said distillation column to receive a distillation vapor stream from a region of said distillation column below said expanded cooled first stream;

(6) first compressing means connected to said vapor withdrawing means to receive said distillation vapor stream and to compress it to an intermediate pressure;

(7) heat exchange means connected to said first compressing means to receive said compressed distillation vapor stream and to cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(8) third expansion means connected to said heat exchange means to receive at least a portion of said condensed stream and to expand it to said lower pressure, said third expansion means being further connected to said distillation column to supply said at least a portion of said expanded condensed stream to said distillation column at a third mid-column feed position located above said expanded cooled first stream;

(9) said distillation column being further connected to said heat exchange means to direct at least a portion of said overhead vapor stream separated therein into heat exchange relation with said compressed distillation vapor stream and to heat said overhead vapor stream, thereby to supply at least a portion of the cooling of step (7);

(10) second compressing means connected to said heat exchange means to receive said heated overhead vapor stream and compress it to higher pressure;

(11) second dividing means connected to said second compressing means to receive said compressed heated overhead vapor stream and divide it into said volatile residue gas fraction and a compressed recycle stream;

(12) third cooling means connected to said second dividing means to receive said compressed recycle stream and cool it sufficiently to substantially condense it;

(13) fourth expansion means connected to said third cooling means to receive said substantially condensed compressed recycle stream and expand it to said lower pressure, said fourth expansion means being further connected to said distillation column to supply said expanded condensed recycle stream to said distillation column at a top feed position; and

(14) 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 portions of the components in said relatively less volatile fraction are recovered.

16. The improvement according to claim 15 wherein

(1) a third dividing means is connected to said distillation column to receive said overhead vapor stream and divide it into at least a first vapor stream and a second vapor stream;

(2) a combining means is connected to said third dividing means and said vapor withdrawing means to receive said first vapor stream and said distillation vapor stream and form a combined vapor stream;

(3) said first compressing means is adapted to be connected to said combining means to receive said combined vapor stream and compress it to said intermediate pressure;

(4) said heat exchange means is adapted to receive said compressed combined vapor stream and cool it sufficiently to condense at least a part of it, thereby forming said condensed stream;

(5) said heat exchange means is further adapted to be connected to said third dividing means to receive said second vapor stream and direct it into heat exchange relation with said compressed combined vapor stream and to heat said second vapor stream, thereby to supply at least a portion of the cooling of step (4);

(6) said second compressing means is adapted to receive said heated second vapor stream and compress it to said higher pressure; and

(7) said second dividing means is adapted to receive said compressed heated second vapor stream and divide it into said volatile residue gas fraction and said compressed recycle stream.

17. The improvement according to claim 16 wherein

(1) a fourth dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said fourth dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said distillation column to supply said expanded first portion to said distillation column at said third mid-column feed position; and

(3) a fifth expansion means is connected to said fourth dividing means to receive said second portion and expand it to said lower pressure, said fifth expansion means being further connected to said distillation column to supply said expanded second portion to said distillation column at a mid-column feed position below that of said expanded first portion.

18. The improvement according to claim 15 wherein

(1) a third dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said third dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said distillation column to supply said expanded first portion to said distillation column at said third mid-column feed position; and

(3) a fifth expansion means is connected to said third dividing means to receive said second portion and expand it to said lower pressure, said fifth expansion means being further connected to said distillation column to supply said expanded second portion to said distillation column at a mid-column feed position below that of said expanded first portion.

19. In an apparatus for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in said apparatus there being

(a) a first cooling means to cool said gas under pressure connected to provide a cooled stream under pressure;

(b) a first expansion means connected to receive at least a portion of said cooled stream under pressure and to expand it to a lower pressure, whereby said stream is further cooled; and

(c) a distillation column connected to receive said further cooled stream, said distillation column being adapted to separate said further cooled stream into an overhead vapor stream and said relatively less volatile fraction;

the improvement wherein said apparatus includes

(1) said first cooling means being adapted to cool said feed gas under pressure sufficiently to partially condense it;

(2) separating means connected to said first cooling means to receive said partially condensed feed and to separate it into a vapor stream and at least one liquid stream;

(3) first dividing means connected to said separating means to receive said vapor stream and to divide it into first and second streams;

(4) second cooling means connected to said first dividing means to receive said first stream and to cool it sufficiently to substantially condense it;

(5) said first expansion means being connected to said second cooling means to receive said substantially condensed first stream and to expand it to said lower pressure, said first expansion means being further connected to said distillation column to supply said expanded cooled first stream to said distillation column at a first mid-column feed position;

(6) second expansion means connected to said first dividing means to receive said second stream and to expand it to said lower pressure, said second expansion means being further connected to said distillation column to supply said expanded second stream to said distillation column at a second mid-column feed position;

(7) vapor withdrawing means connected to said distillation column to receive a distillation vapor stream from a region of said distillation column below said expanded cooled first stream;

(8) first compressing means connected to said vapor withdrawing means to receive said distillation vapor stream and to compress it to an intermediate pressure;

(9) heat exchange means connected to said first compressing means to receive said compressed distillation vapor stream and to cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(10) third expansion means connected to said heat exchange means to receive at least a portion of said condensed stream and to expand it to said lower pressure, said third expansion means being further connected to said distillation column to supply said at least a portion of said expanded condensed stream to said distillation column at a third mid-column feed position located above said expanded cooled first stream;

(11) fourth expansion means connected to said separating means to receive at least a portion of said at least one liquid stream and to expand it to said lower pressure, said fourth expansion means being further connected to said distillation column to supply said expanded liquid stream to said distillation column at a fourth mid-column feed position;

(12) said distillation column being further connected to said heat exchange means to direct at least a portion of said overhead vapor stream separated therein into heat exchange relation with said compressed distillation vapor stream and to heat said overhead vapor stream, thereby to supply at least a portion of the cooling of step (9);

(13) second compressing means connected to said heat exchange means to receive said heated overhead vapor stream and compress it to higher pressure;

(14) second dividing means connected to said second compressing means to receive said compressed heated overhead vapor stream and divide it into said volatile residue gas fraction and a compressed recycle stream;

(15) third cooling means connected to said second dividing means to receive said compressed recycle stream and cool it sufficiently to substantially condense it;

(16) fifth expansion means connected to said third cooling means to receive said substantially condensed compressed recycle stream and expand it to said lower pressure, said fifth expansion means being further connected to said distillation column to supply said expanded condensed recycle stream to said distillation column at a top feed position; 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 portions of the components in said relatively less volatile fraction are recovered.

20. The improvement according to claim 19 wherein

(1) a third dividing means is connected to said distillation column to receive said overhead vapor stream and divide it into at least a first vapor stream and a second vapor stream;

(2) a combining means is connected to said third dividing means and said vapor withdrawing means to receive said first vapor stream and said distillation vapor stream and form a combined vapor stream;

(3) said first compressing means is adapted to be connected to said combining means to receive said combined vapor stream and compress it to said intermediate pressure;

(4) said heat exchange means is adapted to receive said compressed combined vapor stream and cool it sufficiently to condense at least a part of it, thereby forming said condensed stream;

(5) said heat exchange means is further adapted to be connected to said third dividing means to receive said second vapor stream and direct it into heat exchange relation with said compressed combined vapor stream and to heat said second vapor stream, thereby to supply at least a portion of the cooling of step (4);

(6) said second compressing means is adapted to receive said heated second vapor stream and compress it to said higher pressure; and

(7) said second dividing means is adapted to receive said compressed heated second vapor stream and divide it into said volatile residue gas fraction and said compressed recycle stream.

23. The improvement according to claim 20 or 22 wherein

(1) a fourth dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said fourth dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said distillation column to supply said expanded first portion to said distillation column at said third mid-column feed position; and

(3) a sixth expansion means is connected to said fourth dividing means to receive said second portion and expand it to said lower pressure, said sixth expansion means being further connected to said distillation column to supply said expanded second portion to said distillation column at a mid-column feed position below that of said expanded first portion.

24. The improvement according to claim 19 or 21 wherein

(1) a third dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said third dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said distillation column to supply said expanded first portion to said distillation column at said third mid-column feed position; and

(3) a sixth expansion means is connected to said third dividing means to receive said second portion and expand it to said lower pressure, said sixth expansion means being further connected to said distillation column to supply said expanded second portion to said distillation column at a mid-column feed position below that of said expanded first portion.

21. In an apparatus for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in said apparatus there being

(a) a first cooling means to cool said gas under pressure connected to provide a cooled stream under pressure;

(b) a first expansion means connected to receive at least a portion of said cooled stream under pressure and to expand it to a lower pressure, whereby said stream is further cooled; and

(c) a distillation column connected to receive said further cooled stream, said distillation column being adapted to separate said further cooled stream into an overhead vapor stream and said relatively less volatile fraction;

the improvement wherein said apparatus includes

(1) said first cooling means being adapted to cool said feed gas under pressure sufficiently to partially condense it;

(2) separating means connected to said first cooling means to receive said partially condensed feed and to separate it into a vapor stream and at least one liquid stream;

(3) first dividing means connected to said separating means to receive said vapor stream and to divide it into first and second streams;

(4) combining means connected to said first dividing means and said separating means to receive said first stream and at least a portion of said at least one liquid stream and form a combined stream;

(5) second cooling means connected to said combining means to receive said combined stream and to cool it sufficiently to substantially condense it;

(6) said first expansion means being connected to said second cooling means to receive said substantially condensed combined stream and to expand it to said lower pressure, said first expansion means being further connected to said distillation column to supply said expanded cooled combined stream to said distillation column at a first mid-column feed position;

(7) second expansion means connected to said first dividing means to receive said second stream and to expand it to said lower pressure, said second expansion means being further connected to said distillation column to supply said expanded second stream to said distillation column at a second mid-column feed position;

(8) vapor withdrawing means connected to said distillation column to receive a distillation vapor stream from a region of said distillation column below said expanded cooled combined stream;

(9) first compressing means connected to said vapor withdrawing means to receive said distillation vapor stream and to compress it to an intermediate pressure;

(10) heat exchange means connected to said first compressing means to receive said compressed distillation vapor stream and to cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(11) third expansion means connected to said heat exchange means to receive at least a portion of said condensed stream and to expand it to said lower pressure, said third expansion means being further connected to said distillation column to supply said at least a portion of said expanded condensed stream to said distillation column at a third mid-column feed position located above said expanded cooled combined stream;

(12) fourth expansion means connected to said separating means to receive any remaining portion of said at least one liquid stream and to expand it to said lower pressure, said fourth expansion means being further connected to said distillation column to supply said expanded liquid stream to said distillation column at a fourth mid-column feed position;

(13) said distillation column being further connected to said heat exchange means to direct at least a portion of said overhead vapor stream separated therein into heat exchange relation with said compressed distillation vapor stream and to heat said overhead vapor stream, thereby to supply at least a portion of the cooling of step (10);

(14) second compressing means connected to said heat exchange means to receive said heated overhead vapor stream and compress it to higher pressure;

(15) second dividing means connected to said second compressing means to receive said compressed heated overhead vapor stream and divide it into said volatile residue gas fraction and a compressed recycle stream;

(16) third cooling means connected to said second dividing means to receive said compressed recycle stream and cool it sufficiently to substantially condense it;

(17) fifth expansion means connected to said third cooling means to receive said substantially condensed compressed recycle stream and expand it to said lower pressure, said fifth expansion means being further connected to said distillation column to supply said expanded condensed recycle stream to said distillation column at a top feed position; and

(18) 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 portions of the components in said relatively less volatile fraction are recovered.

22. The improvement according to claim 21 wherein

(1) a third dividing means is connected to said distillation column to receive said overhead vapor stream and divide it into at least a first vapor stream and a second vapor stream;

(2) a second combining means is connected to said third dividing means and said vapor withdrawing means to receive said first vapor stream and said distillation vapor stream and form a combined vapor stream;

(3) said first compressing means is adapted to be connected to said second combining means to receive said combined vapor stream and compress it to said intermediate pressure;

(4) said heat exchange means is adapted to receive said compressed combined vapor stream and cool it sufficiently to condense at least a part of it, thereby forming said condensed stream;

(5) said heat exchange means is further adapted to be connected to said third dividing means to receive said second vapor stream and direct it into heat exchange relation with said compressed combined vapor stream and to heat said second vapor stream, thereby to supply at least a portion of the cooling of step (4);

(6) said second compressing means is adapted to receive said heated second vapor stream and compress it to said higher pressure; and

(7) said second dividing means is adapted to receive said compressed heated second vapor stream and divide it into said volatile residue gas fraction and said compressed recycle stream.

25. In an apparatus for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in said apparatus there being

(a) a first cooling means to cool said gas under pressure connected to provide a cooled stream under pressure;

(b) a first expansion means connected to receive at least a portion of said cooled stream under pressure and to expand it to a lower pressure, whereby said stream is further cooled; and

(c) a distillation column connected to receive said further cooled stream, said distillation column being adapted to separate said further cooled stream into a first overhead vapor stream and said relatively less volatile fraction;

the improvement wherein said apparatus includes

(1) first dividing means connected to said first cooling means to receive said cooled stream and to divide it into first and second streams;

(2) second cooling means connected to said first dividing means to receive said first stream and to cool it sufficiently to substantially condense it;

(3) said first expansion means being connected to said second cooling means to receive said substantially condensed first stream and to expand it to said lower pressure, said first expansion means being further connected to a contacting and separating means to supply said expanded cooled first stream to said contacting and separating means at a first mid-column feed position, said contacting and separating means being adapted to produce a second overhead vapor stream and a bottom liquid stream;

(4) said distillation column being connected to said contacting and separating means to receive at least a portion of said bottom liquid stream, said distillation column being further connected to said contacting and separating means to direct said first overhead vapor stream separated therein to said contacting and separating means at a first lower feed position;

(5) second expansion means connected to said first dividing means to receive said second stream and to expand it to said lower pressure, said second expansion means being further connected to said contacting and separating means to supply said expanded second stream to said contacting and separating means at a second lower feed position;

(6) vapor withdrawing means connected to said contacting and separating means to receive a distillation vapor stream from a region of said contacting and separating means below said expanded cooled first stream;

(7) first compressing means connected to said vapor withdrawing means to receive said distillation vapor stream and to compress it to an intermediate pressure;

(8) heat exchange means connected to said first compressing means to receive said compressed distillation vapor stream and to cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(9) third expansion means connected to said heat exchange means to receive at least a portion of said condensed stream and to expand it to said lower pressure, said third expansion means being further connected to said contacting and separating means to supply said at least a portion of said expanded condensed stream to said contacting and separating means at a second mid-column feed position located above said expanded cooled first stream;

(10) said contacting and separating means being further connected to said heat exchange means to direct at least a portion of said second overhead vapor stream separated therein into heat exchange relation with said compressed distillation vapor stream and to heat said second overhead vapor stream, thereby to supply at least a portion of the cooling of step (8);

(11) second compressing means connected to said heat exchange means to receive said heated second overhead vapor stream and compress it to higher pressure;

(12) second dividing means connected to said second compressing means to receive said compressed heated second overhead vapor stream and divide it into said volatile residue gas fraction and a compressed recycle stream;

(13) third cooling means connected to said second dividing means to receive said compressed recycle stream and cool it sufficiently to substantially condense it;

(14) fourth expansion means connected to said third cooling means to receive said substantially condensed compressed recycle stream and expand it to said lower pressure, said fourth expansion means being further connected to said contacting and separating means to supply said expanded condensed recycle stream to said contacting and separating means at a top feed position; and

(15) control means adapted to regulate the quantities and temperatures of said feed streams to said contacting and separating means to maintain the overhead temperature of said contacting and separating means at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered.

26. The improvement according to claim 25 wherein

(1) a third dividing means is connected to said contacting and separating means to receive said second overhead vapor stream and divide it into at least a first vapor stream and a second vapor stream;

(2) a combining means is connected to said third dividing means and said vapor withdrawing means to receive said first vapor stream and said distillation vapor stream and form a combined vapor stream;

(3) said first compressing means is adapted to be connected to said combining means to receive said combined vapor stream and compress it to said intermediate pressure;

(4) said heat exchange means is adapted to receive said compressed combined vapor stream and cool it sufficiently to condense at least a part of it, thereby forming said condensed stream;

(5) said heat exchange means is further adapted to be connected to said third dividing means to receive said second vapor stream and direct it into heat exchange relation with said compressed combined vapor stream and to heat said second vapor stream, thereby to supply at least a portion of the cooling of step (4);

(6) said second compressing means is adapted to receive said heated second vapor stream and compress it to said higher pressure; and

(7) said second dividing means is adapted to receive said compressed heated second vapor stream and divide it into said volatile residue gas fraction and said compressed recycle stream.

27. The improvement according to claim 26 wherein

(1) a fourth dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said fourth dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said contacting and separating means to supply said expanded first portion to said contacting and separating means at said second mid-column feed position; and

(3) a fifth expansion means is connected to said fourth dividing means to receive said second portion and expand it to said lower pressure, said fifth expansion means being further connected to said contacting and separating means to supply said expanded second portion to said contacting and separating means at a mid-column feed position below that of said expanded first portion.

28. The improvement according to claim 25 wherein

(1) a third dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said third dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said contacting and separating means to supply said expanded first portion to said contacting and separating means at said second mid-column feed position; and

(3) a fifth expansion means is connected to said third dividing means to receive said second portion and expand it to said lower pressure, said fifth expansion means being further connected to said contacting and separating means to supply said expanded second portion to said contacting and separating means at a mid-column feed position below that of said expanded first portion.

29. In an apparatus for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in said apparatus there being

(a) a first cooling means to cool said gas under pressure connected to provide a cooled stream under pressure;

(b) a first expansion means connected to receive at least a portion of said cooled stream under pressure and to expand it to a lower pressure, whereby said stream is further cooled; and

(c) a distillation column connected to receive said further cooled stream, said distillation column being adapted to separate said further cooled stream into a first overhead vapor stream and said relatively less volatile fraction;

the improvement wherein said apparatus includes

(1) said first cooling means being adapted to cool said feed gas under pressure sufficiently to partially condense it;

(2) separating means connected to said first cooling means to receive said partially condensed feed and to separate it into a vapor stream and at least one liquid stream;

(3) first dividing means connected to said separating means to receive said vapor stream and to divide it into first and second streams;

(4) second cooling means connected to said first dividing means to receive said first stream and to cool it sufficiently to substantially condense it;

(5) said first expansion means being connected to said second cooling means to receive said substantially condensed first stream and to expand it to said lower pressure, said first expansion means being further connected to a contacting and separating means to supply said expanded cooled first stream to said contacting and separating means at a first mid-column feed position, said contacting and separating means being adapted to produce a second overhead vapor stream and a bottom liquid stream;

(6) said distillation column being connected to said contacting and separating means to receive at least a portion of said bottom liquid stream, said distillation column being further connected to said contacting and separating means to direct said first overhead vapor stream separated therein to said contacting and separating means at a first lower feed position;

(7) second expansion means connected to said first dividing means to receive said second stream and to expand it to said lower pressure, said second expansion means being further connected to said contacting and separating means to supply said expanded second stream to said contacting and separating means at a second lower feed position;

(8) vapor withdrawing means connected to said contacting and separating means to receive a distillation vapor stream from a region of said contacting and separating means below said expanded cooled first stream;

(9) first compressing means connected to said vapor withdrawing means to receive said distillation vapor stream and to compress it to an intermediate pressure;

(10) heat exchange means connected to said first compressing means to receive said compressed distillation vapor stream and to cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(11) third expansion means connected to said heat exchange means to receive at least a portion of said condensed stream and to expand it to said lower pressure, said third expansion means being further connected to said contacting and separating means to supply said at least a portion of said expanded condensed stream to said contacting and separating means at a second mid-column feed position located above said expanded cooled first stream;

(12) fourth expansion means connected to said separating means to receive at least a portion of said at least one liquid stream and to expand it to said lower pressure, said fourth expansion means being further connected to said distillation column to supply said expanded liquid stream to said distillation column at a mid-column feed position;

(13) said contacting and separating means being further connected to said heat exchange means to direct at least a portion of said second overhead vapor stream separated therein into heat exchange relation with said compressed distillation vapor stream and to heat said second overhead vapor stream, thereby to supply at least a portion of the cooling of step (10);

(14) second compressing means connected to said heat exchange means to receive said heated second overhead vapor stream and compress it to higher pressure;

(15) second dividing means connected to said second compressing means to receive said compressed heated second overhead vapor stream and divide it into said volatile residue gas fraction and a compressed recycle stream;

(16) third cooling means connected to said second dividing means to receive said compressed recycle stream and cool it sufficiently to substantially condense it;

(17) fifth expansion means connected to said third cooling means to receive said substantially condensed compressed recycle stream and expand it to said lower pressure, said fifth expansion means being further connected to said contacting and separating means to supply said expanded condensed recycle stream to said contacting and separating means at a top feed position; and

(18) control means adapted to regulate the quantities and temperatures of said feed streams to said contacting and separating means to maintain the overhead temperature of said contacting and separating means at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered.

30. The improvement according to claim 29 wherein

(1) a third dividing means is connected to said contacting and separating means to receive said second overhead vapor stream and divide it into at least a first vapor stream and a second vapor stream;

(2) a combining means is connected to said third dividing means and said vapor withdrawing means to receive said first vapor stream and said distillation vapor stream and form a combined vapor stream;

(3) said first compressing means is adapted to be connected to said combining means to receive said combined vapor stream and compress it to said intermediate pressure;

(4) said heat exchange means is adapted to receive said compressed combined vapor stream and cool it sufficiently to condense at least a part of it, thereby forming said condensed stream;

(5) said heat exchange means is further adapted to be connected to said third dividing means to receive said second vapor stream and direct it into heat exchange relation with said compressed combined vapor stream and to heat said second vapor stream, thereby to supply at least a portion of the cooling of step (4);

(6) said second compressing means is adapted to receive said heated second vapor stream and compress it to said higher pressure; and

(7) said second dividing means is adapted to receive said compressed heated second vapor stream and divide it into said volatile residue gas fraction and said compressed recycle stream.

33. The improvement according to claim 30 or 32 wherein

(1) a fourth dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said fourth dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said contacting and separating means to supply said expanded first portion to said contacting and separating means at said second mid-column feed position; and

(3) a sixth expansion means is connected to said fourth dividing means to receive said second portion and expand it to said lower pressure, said sixth expansion means being further connected to said contacting and separating means to supply said expanded second portion to said contacting and separating means at a mid-column feed position below that of said expanded first portion.

34. The improvement according to claim 29 or 31 wherein

(1) a third dividing means is connected to said heat exchange means to receive said condensed stream and divide it into at least a first portion and a second portion;

(2) said third expansion means is adapted to be connected to said third dividing means to receive said first portion and expand it to said lower pressure, said third expansion means being further connected to said contacting and separating means to supply said expanded first portion to said contacting and separating means at said second mid-column feed position; and

(3) a sixth expansion means is connected to said third dividing means to receive said second portion and expand it to said lower pressure, said sixth expansion means being further connected to said contacting and separating means to supply said expanded second portion to said contacting and separating means at a mid-column feed position below that of said expanded first portion.

31. In an apparatus for the separation of a gas stream containing methane, C₂ components, C₃ components, and heavier hydrocarbon components into a volatile residue gas fraction and a relatively less volatile fraction containing a major portion of said C₂ components, C₃ components, and heavier hydrocarbon components or said C₃ components and heavier hydrocarbon components, in said apparatus there being

(a) a first cooling means to cool said gas under pressure connected to provide a cooled stream under pressure;

(b) a first expansion means connected to receive at least a portion of said cooled stream under pressure and to expand it to a lower pressure, whereby said stream is further cooled; and

(c) a distillation column connected to receive said further cooled stream, said distillation column being adapted to separate said further cooled stream into a first overhead vapor stream and said relatively less volatile fraction;

the improvement wherein said apparatus includes

(1) said first cooling means being adapted to cool said feed gas under pressure sufficiently to partially condense it;

(2) separating means connected to said first cooling means to receive said partially condensed feed and to separate it into a vapor stream and at least one liquid stream;

(3) first dividing means connected to said separating means to receive said vapor stream and to divide it into first and second streams;

(4) combining means connected to said first dividing means and said separating means to receive said first stream and at least a portion of said at least one liquid stream and form a combined stream;

(5) second cooling means connected to said combining means to receive said combined stream and to cool it sufficiently to substantially condense it;

(6) said first expansion means being connected to said second cooling means to receive said substantially condensed combined stream and to expand it to said lower pressure, said first expansion means being further connected to a contacting and separating means to supply said expanded cooled combined stream to said contacting and separating means at a first mid-column feed position, said contacting and separating means being adapted to produce a second overhead vapor stream and a bottom liquid stream;

(7) said distillation column being connected to said contacting and separating means to receive at least a portion of said bottom liquid stream, said distillation column being further connected to said contacting and separating means to direct said first overhead vapor stream separated therein to said contacting and separating means at a first lower feed position;

(8) second expansion means connected to said first dividing means to receive said second stream and to expand it to said lower pressure, said second expansion means being further connected to said contacting and separating means to supply said expanded second stream to said contacting and separating means at a second lower feed position;

(9) vapor withdrawing means connected to said contacting and separating means to receive a distillation vapor stream from a region of said contacting and separating means below said expanded cooled combined stream;

(10) first compressing means connected to said vapor withdrawing means to receive said distillation vapor stream and to compress it to an intermediate pressure;

(11) heat exchange means connected to said first compressing means to receive said compressed distillation vapor stream and to cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(12) third expansion means connected to said heat exchange means to receive at least a portion of said condensed stream and to expand it to said lower pressure, said third expansion means being further connected to said contacting and separating means to supply said at least a portion of said expanded condensed stream to said contacting and separating means at a second mid-column feed position located above said expanded cooled combined stream;

(13) fourth expansion means connected to said separating means to receive any remaining portion of said at least one liquid stream and to expand it to said lower pressure, said fourth expansion means being further connected to said distillation column to supply said expanded liquid stream to said distillation column at a mid-column feed position;

(14) said contacting and separating means being further connected to said heat exchange means to direct at least a portion of said second overhead vapor stream separated therein into heat exchange relation with said compressed distillation vapor stream and to heat said second overhead vapor stream, thereby to supply at least a portion of the cooling of step (11);

(15) second compressing means connected to said heat exchange means to receive said heated second overhead vapor stream and compress it to higher pressure;

(16) second dividing means connected to said second compressing means to receive said compressed heated second overhead vapor stream and divide it into said volatile residue gas fraction and a compressed recycle stream;

(17) third cooling means connected to said second dividing means to receive said compressed recycle stream and cool it sufficiently to substantially condense it;

(18) fifth expansion means connected to said third cooling means to receive said substantially condensed compressed recycle stream and expand it to said lower pressure, said fifth expansion means being further connected to said contacting and separating means to supply said expanded condensed recycle stream to said contacting and separating means at a top feed position; and

(19) control means adapted to regulate the quantities and temperatures of said feed streams to said contacting and separating means to maintain the overhead temperature of said contacting and separating means at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered.

32. The improvement according to claim 31 wherein

(1) a third dividing means is connected to said contacting and separating means to receive said second overhead vapor stream and divide it into at least a first vapor stream and a second vapor stream;

(2) a second combining means is connected to said third dividing means and said vapor withdrawing means to receive said first vapor stream and said distillation vapor stream and form a combined vapor stream;

(3) said first compressing means is adapted to be connected to said second combining means to receive said combined vapor stream and compress it to said intermediate pressure;

(4) said heat exchange means is adapted to receive said compressed combined vapor stream and cool it sufficiently to condense at least a part of it, thereby forming said condensed stream;

(5) said heat exchange means is further adapted to be connected to said third dividing means to receive said second vapor stream and direct it into heat exchange relation with said compressed combined vapor stream and to heat said second vapor stream, thereby to supply at least a portion of the cooling of step (4);

(6) said second compressing means is adapted to receive said heated second vapor stream and compress it to said higher pressure; and

(7) said second dividing means is adapted to receive said compressed heated second vapor stream and divide it into said volatile residue gas fraction and said compressed recycle stream.