Hydrocabon gas processing

• US 8,667,812 B2
• Filed: 05/27/2011
• Issued: 03/11/2014
• Est. Priority Date: 06/03/2010
• Status: Active Grant

• Current Assignee: UOP Llc (Honeywell International Inc.)
• Original Assignee: Ordoff Engineers Limited
• Inventors: Cuellar, Kyle T., Wilkinson, John D., Hudson, Hank M.
• Primary Examiner(s): Flanigan, Allen
• Assistant Examiner(s): YAVARI, JOHAN C
• Application Number:
  US13/117,242
• Publication Number:
  US 20110296867A1
• Time in Patent Office: 1,019 Days
• Field of Search: 62618-622, 626/25, 62630-632, 629/29
• US Class Current: 62/621
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/70 Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
• CPC Class Codes: F25J 2205/02 using simple phase separation in a vessel or drum
• CPC Class Codes: F25J 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2210/12 Refinery or petrochemical off-gas
• CPC Class Codes: F25J 2220/82 Separating low boiling, i.e. more volatile components, e.g. He, H2, CO, Air gases, CH4
• 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 2230/80 the fluid being carbon dioxide
• CPC Class Codes: F25J 2235/80 the fluid being carbon dioxide
• 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 2260/80 Integration in an installation using carbon dioxide, e.g. for EOR, sequestration, refrigeration etc.
• CPC Class Codes: F25J 2270/02 Internal refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 2270/12 External refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 3/0209 Natural gas or substitute natural gas
• CPC Class Codes: F25J 3/0219 Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• CPC Class Codes: F25J 3/0223 H2/CO mixtures, i.e. synthesis gas; Water gas or shifted synthesis gas production of carbon monoxide containing gas in general C01B32/40, C10J, C10K; production of hydrogen containing gas C01B3/00
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0252 separation of hydrogen production of hydrogen containing gas in general C01B3/00, e.g. separation of hydrogen or hydrogen containing gases form gaseous mixtures at low temperatures C01B3/506
• CPC Class Codes: F25J 3/0266 : separation of carbon dioxide production of carbon dioxide in general C01B32/00
• CPC Class Codes: Y02C 20/40 : of CO2

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.

Claims

1. 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.

2. 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 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.

3. 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 element (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 element (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 element (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 element (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.

5. The apparatus according to claim 3 wherein said first heat exchange means is further connected to said third heat exchange means to receive said heated expanded condensed stream and further heat it, thereby to supply at least a portion of the cooling of element (1), said first heat exchange means being further connected to said distillation column to supply said further heated expanded condensed stream to said distillation column at said mid-column feed position.

4. 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 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 element (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 element (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 element (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 element (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.

6. The apparatus according to claim 4 wherein said first heat exchange means is further connected to said third heat exchange means to receive said heated expanded condensed stream and further heat it, thereby to supply at least a portion of the cooling of element (1), said first heat exchange means being further connected to said distillation column to supply said further heated expanded condensed stream to said distillation column at said lower mid-column feed position.