Hydrocarbon gas processing

• US 5,771,712 A
• Filed: 08/13/1996
• Issued: 06/30/1998
• Est. Priority Date: 06/07/1995
• Status: Expired due to Term

• Current Assignee: UOP Llc (Honeywell International Inc.)
• Original Assignee: Elcor Corporation
• Inventors: Campbell, Roy E., Hudson, Hank M., Wilkinson, John D.
• Primary Examiner(s): Capossela, Ronald C.
• Application Number:
  US08/696,114
• Time in Patent Office: 686 Days
• Field of Search: 62/621, 62/625
• US Class Current: 62/621
• CPC Class Codes: C07C 7/005 Processes comprising at least two steps in series
• CPC Class Codes: C10G 70/041 by distillation
• CPC Class Codes: F25J 2200/04 in a dual 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 2200/74 Refluxing the column with at least a part of the partially condensed overhead gas
• CPC Class Codes: F25J 2200/78 Refluxing the column with a liquid stream originating from an upstream or downstream fractionator column
• 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 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 2270/04 Internal refrigeration with work-producing gas expansion 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 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0242 separation of CnHm with 3 carbon atoms or more

Abstract

A process for the recovery of propane, propylene and heavier hydrocarbon components from a hydrocarbon gas stream is disclosed. The stream is cooled and/or expanded to partially condense it, then separated to provide a first vapor stream. The first vapor stream is directed into a contacting device whereby a third vapor stream and a C₃ -containing liquid stream are formed. The C₃ -containing liquid stream is directed to a distillation column wherein a second vapor stream is separated to recover a product containing the major portion of the C₃ components and heavier hydrocarbon components. The second vapor stream is directed into heat exchange relation with the third vapor stream to cool the second vapor stream and condense at least a part of it, forming a condensed stream. At least a portion of the condensed stream is directed to the contacting device to intimately contact the first vapor stream; the remaining portion of the condensed stream is supplied to the distillation column as its top feed. The quantities and temperatures of the feeds to the contacting device and the distillation column are effective to maintain the overhead temperatures of the contacting device and the distillation column at temperatures 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 containing a major portion of said methane and C₂ components and a relatively less volatile fraction containing a major portion of said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is treated in one or more heat exchange and/or expansion steps to partially condense at least a portion thereof and provide thereby at least a first vapor stream and at least one first C₃ -containing liquid stream which also contains lighter hydrocarbons;

and

(b) at least one of said first C₃ -containing liquid streams is directed into a distillation column wherein said liquid is separated into a second vapor stream containing predominantly methane and C₂ components and said relatively less volatile fraction containing the major portion of said C₃ components and heavier hydrocarbon components;

the improvement wherein

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

(2) a portion of said condensed stream is supplied to said distillation column at a top feed position;

(3) at least a portion of said first vapor stream is intimately contacted with at least part of the remaining portion of said condensed stream in a contacting device having no more than one fractionation zone, thereby forming a third vapor stream and a second C₃ -containing liquid stream;

(4) said second C₃ -containing liquid stream is supplied to said distillation column as a second feed thereto;

(5) at least a portion of said third vapor stream is directed into heat exchange relation with said second vapor stream, thereby to supply the cooling of step (1) and thereafter discharging at least a portion of said third vapor stream as said volatile residue gas fraction;

(6) said first C₃ -containing liquid stream is heated and supplied to said distillation column as a third feed thereto; and

(7) the quantities and temperatures of said feed streams to said contacting device and said distillation column are effective to maintain the overhead temperatures of said contacting device and said distillation column at temperatures whereby the major portion of said C₃ components and heavier hydrocarbon components is recovered in said relatively less volatile fraction.

2. The improvement according to claim 1 wherein at least a portion of said second C₃ -containing liquid stream is heated prior to supplying said second C₃ -containing liquid stream to said distillation column.

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 containing a major portion of said methane and C₂ components and a relatively less volatile fraction containing a major portion of said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is treated in one or more heat exchange and/or expansion steps to partially condense at least a portion thereof and provide thereby at least a first vapor stream and at least one first C₃ -containing liquid stream which also contains lighter hydrocarbons;

and

(b) at least one of said first C₃ -containing liquid streams is directed into a distillation column wherein said liquid is separated into a second vapor stream containing predominantly methane and C₂ components and said relatively less volatile fraction containing the major portion of said C₃ components and heavier hydrocarbon components;

the improvement wherein

(1) said second vapor stream is cooled sufficiently to partially condense it, thereby forming a partially condensed stream;

(2) said partially condensed stream is separated, thereby to form a third vapor stream and a second C₃ -containing liquid stream;

(3) at least a portion of said second C₃ -containing liquid stream is supplied to said distillation column at a top feed position;

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

(5) at least a portion of said first vapor stream is intimately contacted with at least a portion of said condensed stream in a contacting device, having no more than one fractionation zone thereby forming a fourth vapor stream and a third C₃ -containing liquid stream;

(6) at least a portion of said third C₃ -containing liquid stream is directed into heat exchange relation with said second vapor stream leaving the upper region of said distillation column, thereby to supply the cooling of step (1) and partially condense said second vapor stream;

(7) said third C₃ -containing liquid stream is thereafter supplied to said distillation column as a second feed thereto;

(8) at least a portion of said fourth vapor stream is directed into heat exchange relation with said third vapor stream, thereby to supply the cooling of step (4) and thereafter discharging at least a portion of said fourth vapor stream as said volatile residue gas fraction;

(9) said first C₃ -containing liquid stream is heated and supplied to said distillation column as a third feed thereto; and

(10) the quantities and temperatures of said feed streams to said contacting device and said distillation column are effective to maintain the overhead temperatures of said contacting device and said distillation column at temperatures whereby the major portion of said C₃ components and heavier hydrocarbon components is recovered in said relatively less volatile fraction.

4. The improvement according to claim 3 wherein at least a portion of said third C₃ -containing liquid stream is heated prior to being directed into heat exchange relation with said second vapor stream.

5. 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 containing a major portion of said methane and C₂ components and a relatively less volatile fraction containing a major portion of said C₃ components and heavier hydrocarbon components, in which process

(a) said gas stream is treated in one or more heat exchange and/or expansion steps to partially condense at least a portion thereof and provide thereby at least a first vapor stream and at least one first C₃ -containing liquid stream which also contains lighter hydrocarbons;

and

(b) at least one of said first C₃ -containing liquid streams is directed into a distillation column wherein said liquid is separated into a second vapor stream containing predominantly methane and C₂ components and said relatively less volatile fraction containing the major portion of said C₃ components and heavier hydrocarbon components;

the improvement wherein

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

(2) at least a portion of said first vapor stream is intimately contacted with at least a portion of said condensed stream in a contacting device having no more than one fractionation zone, thereby forming a third vapor stream and a second C₃ -containing liquid stream;

(3) at least a portion of said second C₃ -containing liquid stream is heated and is thereafter supplied to said distillation column at a top feed position;

(4) at least a portion of said third vapor stream is directed into heat exchange relation with said second vapor stream, thereby to supply the cooling of step (1) and thereafter discharging at least a portion of said third vapor stream as said volatile residue gas fraction;

(5) said first C₃ -containing liquid stream is heated and supplied to said distillation column as a second feed thereto; and

(6) the quantities and temperatures of said feed streams to said contacting device and said distillation column are effective to maintain the overhead temperatures of said contacting device and said distillation column at temperatures whereby the major portion of said C₃ components and heavier hydrocarbon components is recovered in said relatively less volatile fraction.

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

(a) one or more first heat exchange means and/or expansion means cooperatively connected to provide at least one partially condensed gas stream,

(b) separation means connected to receive said partially condensed gas stream, thereby providing thereby at least a first vapor stream and at least one first C₃ -containing liquid which also contains lighter hydrocarbons;

and

(c) a distillation column connected to receive at least one of said first C₃ -containing liquid streams which is adapted to separate said stream into a second vapor stream containing predominantly methane and C₂ components and said relatively less volatile fraction containing the major portion of said C₃ components and heavier hydrocarbon components;

the improvement wherein said apparatus includes

(1) second heat exchange means connected to said distillation column to receive said second vapor stream and cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(2) dividing means connected to receive said condensed stream and to divide said condensed stream into first and second liquid streams, said dividing means being further connected to said distillation column to supply said first liquid stream to said distillation column at a top feed position;

(3) contacting and separating means connected to receive at least a portion of said second liquid stream and at least a portion of said first vapor stream wherein said liquid and vapor are commingled in a contacting device having no more than one fractionation zone, said contacting and separating means including separating means to separate the vapor and liquid after contact in said contacting device to form a third vapor stream and a second C₃ -containing liquid stream;

(4) said contacting and separating means being further connected to said distillation column to supply said second C₃ -containing liquid stream separated therein to said distillation column as a second feed thereto;

(5) said contacting and separating means being further connected to said second heat exchange means to direct at least a portion of said third vapor stream separated therein into heat exchange relation with said second vapor stream;

(6) first heat exchange means connected to said separation means to receive said first C₃ -containing liquid and heat it;

said first heat exchange means being further connected to said distillation column to provide said heated first C₃ -containing liquid as a third feed thereto; and

(7) control means adapted to regulate the quantities and temperatures of said feed streams to said contacting and separating means and said distillation column to maintain the overhead temperatures of said contacting and separating means and said distillation column at temperatures whereby the major portion of said C₃ components and heavier components is recovered in said relatively less volatile fraction.

7. The improvement according to claim 6 wherein said contacting and separating means is connected to said first heat exchange means whereby at least a portion of said second C₃ -containing liquid stream separated therein is heated, said first heat exchange means being further connected to said distillation column to supply said heated second C₃ -containing liquid stream to said distillation column as a second feed thereto.

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

(a) one or more first heat exchange means and/or expansion means cooperatively connected to provide at least one partially condensed gas stream,

(b) first separation means connected to receive said partially condensed gas stream, thereby providing thereby at least a first vapor stream and at least one first C₃ -containing liquid which also contains lighter hydrocarbons;

and

(c) a distillation column connected to receive at least one of said first C₃ -containing liquid streams which is adapted to separate said stream into a second vapor stream containing predominantly methane and C₂ components and said relatively less volatile fraction containing the major portion of said C₃ components and heavier hydrocarbon components;

the improvement wherein said apparatus includes

(1) second heat exchange means connected to said distillation column to receive said second vapor stream and cool it sufficiently to partially condense it, thereby forming a partially condensed stream;

(2) second separating means connected to said second heat exchange means to receive said partially condensed stream and separate it, thereby to form a third vapor stream and a second C₃ -containing liquid stream, said second separating means being further connected to said distillation column to supply at least a portion of said second C₃ -containing liquid stream to said distillation column at a top feed position;

(3) third heat exchange means connected to said second separating means to receive said third vapor stream and cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(4) contacting and separating means connected to receive at least a portion of said condensed stream and at least a portion of said first vapor stream wherein said liquid and vapor are commingled in a contacting device having no more than one fractionation zone, said contacting and separating means including separating means to separate the vapor and liquid after contact in said contacting device to form a fourth vapor stream and a third C₃ -containing liquid stream;

(5) said second heat exchange means being further connected to said contacting and separating means to receive at least a portion of said third C₃ -containing liquid stream separated therein and direct it into heat exchange relation with said second vapor stream leaving the upper region of said distillation column, thereby to cool and partially condense said second vapor stream;

(6) said second heat exchange means being further connected to said distillation column to supply said third C₃ -containing liquid stream to said distillation column as a second feed thereto;

(7) said contacting and separating means being further connected to said third heat exchange means to direct at least a portion of said fourth vapor stream separated therein into heat exchange relation with said third vapor stream;

(8) first heat exchange means connected to said separation means to receive said first C₃ -containing liquid and heat it;

said first heat exchange means being further connected to said distillation column to provide said heated first C₃ -containing liquid as a third feed thereto; and

(9) control means adapted to regulate the quantities and temperatures of said feed streams to said contacting and separating means and said distillation column to maintain the overhead temperatures of said contacting and separating means and said distillation column at temperatures whereby the major portion of said C₃ components and heavier components is recovered in said relatively less volatile fraction.

9. The improvement according to claim 8 wherein said contacting and separating means is connected to said first heat exchange means whereby at least a portion of said third C₃ -containing liquid stream separated therein is heated, said first heat exchange means being further connected to said second heat exchange means to direct said heated third C₃ -containing liquid stream into heat exchange relation with said second vapor stream leaving the upper region of said distillation column.

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

(a) one or more first heat exchange means and/or expansion means cooperatively connected to provide at least one partially condensed gas stream,

(b) separation means connected to receive said partially condensed gas stream thereby providing thereby at least a first vapor stream and at least one first C₃ -containing liquid which also contains lighter hydrocarbons;

and

(c) a distillation column connected to receive at least one of said first C₃ -containing liquid streams which is adapted to separate said stream into a second vapor stream containing predominantly methane and C₂ components and said relatively less volatile fraction containing the major portion of said C₃ components and heavier hydrocarbon components;

the improvement wherein said apparatus includes

(1) second heat exchange means connected to said distillation column to receive said second vapor stream and cool it sufficiently to condense at least a part of it, thereby forming a condensed stream;

(2) contacting and separating means connected to receive at least a portion of said condensed stream and at least a portion of said first vapor stream wherein said liquid and vapor are commingled in a contacting device having no more than one fractionation zone, said contacting and separating means including separating means to separate the vapor and liquid after contact in said contacting device to form a third vapor stream and a second C₃ -containing liquid stream;

(3) first heat exchange means connected to said contacting and separating means to receive at least a portion of said second C₃ -containing liquid stream separated therein and heat it, said first heat exchange means being further connected to said distillation column to supply said heated second C₃ -containing liquid stream to said distillation column at a top feed position;

(4) said contacting and separating means being further connected to said second heat exchange means to direct at least a portion of said third vapor stream separated therein into heat exchange relation with said second vapor stream;

(5) said first exchange means further connected to said separation means to receive said first C₃ -containing liquid and heat it;

said first heat exchange means being further connected to said distillation column to provide said heated first C₃ -containing liquid as a third feed thereto; and

(6) control means adapted to regulate the quantities and temperatures of said feed streams to said contacting and separating means and said distillation column to maintain the overhead temperatures of said contacting and separating means and said distillation column at temperatures whereby the major portion of said C₃ components and heavier components is recovered in said relatively less volatile fraction.