Helium Recovery From Natural Gas Integrated With NGL Recovery

• US 20110174017A1
• Filed: 07/28/2009
• Published: 07/21/2011
• Est. Priority Date: 10/07/2008
• Status: Abandoned Application

• Current Assignee: Donald Victory, Michael W. Miles, Russell H. Oelfke
• Original Assignee: Donald Victory, Michael W. Miles, Russell H. Oelfke
• Inventors: Oelfke, Russell H., Victory, Donald, Miles, Michael W.
• Application Number:
  US13/063,909
• Publication Number:
  US 20110174017A1
• Time in Patent Office: Days
• US Class Current: 62/620
• 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 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 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 2290/80 Retrofitting, revamping or debottlenecking of existing plant
• 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 3/029 of helium

Abstract

The invention relates to a process for producing a helium-enriched vapor stream, a methane-enriched vapor stream, and a liquid stream enriched in hydrocarbons heavier than methane from a pressurized, multicomponent, multiphase stream comprising methane (C₁), helium (He) and hydrocarbons heavier than methane (C₂₊). The process includes cooling the multiphase stream to produce at least one vapor stream enriched in helium and at least one liquid stream, withdrawing at least a portion of the at least one vapor stream as a helium-enriched product stream, passing at least a portion of the at least one liquid stream to a demethanizer, withdrawing from the demethanizer a vapor enriched in methane (C₁), and withdrawing from the demethanizer a liquid enriched in hydrocarbons heavier than methane (C₂₊).

Claims

1. A process for producing a helium-enriched vapor stream, a methane-enriched vapor stream, and a liquid stream enriched in hydrocarbons heavier than methane from a pressurized, multicomponent, multiphase stream comprising methane (C₁), helium (He) and hydrocarbons heavier than methane (C₂₊), the process comprising the steps of:

(a) cooling the multiphase stream to produce at least one vapor stream enriched in helium and at least one liquid stream;

(b) withdrawing at least a portion of the at least one vapor stream as a helium-enriched product stream;

(c) passing at least a portion of the at least one liquid stream to a demethanizer;

(d) withdrawing from the demethanizer a vapor enriched in methane (C₁); and

(e) withdrawing from the demethanizer a liquid enriched in hydrocarbons heavier than methane (C₂₊).

2. The process of claim 1 wherein the step of cooling the feed stream is carried out using one or more heat exchangers.

3. The process of claim 1 further comprising, after cooling the multiphase stream, passing the cooled multiphase stream to a phase separator which separates the cooled feed stream into the at least one vapor stream and the at least one liquid stream.

4. The method of claim 3 further comprising withdrawing the at least one liquid stream from the phase separator and passing the at least one liquid stream to a flow regulating device and thereafter passing at least a portion of the at least one liquid stream to the demethanizer.

5. A process for producing a helium-enriched vapor stream, a methane-enriched vapor stream, and a liquid stream enriched in hydrocarbons heavier than methane (C₂₊) from a pressurized, multicomponent, multiphase feed stream comprising methane (C₁), helium (He) and hydrocarbons heavier than methane (C₂₊), the process comprising the steps of:

(a) passing the feed stream into a first phase separator to produce a first vapor phase and a first liquid phase;

(b) withdrawing the first vapor phase from the first phase separator;

(c) separating the first vapor phase into a second vapor phase and a third vapor phase;

(d) cooling the second vapor phase by indirect heat exchange in a heat exchanger;

(e) expanding the cooled second vapor phase to produce a reduced-pressure vapor phase and reduced-pressure liquid phase, and passing the reduced-pressure vapor and liquid phases to a second phase separator;

(f) withdrawing from the second phase separator a helium-enriched vapor phase;

(g) withdrawing liquid from the second phase separator and passing the withdrawn liquid to a first flow regulating device;

(h) passing the liquid from the flow regulating device to a demethanizer;

(i) expanding the third vapor phase of step (c) to produce a reduced-pressure vapor phase and reduced-pressure pressure liquid phase, and passing the reduced-pressure vapor and liquid phases to the demethanizer;

(j) withdrawing liquid from the first phase separator and passing the withdrawn liquid to a second flow regulating device;

(k) passing the liquid from the second flow regulating device to the demethanizer;

(l) withdrawing from the demethanizer a vapor enriched in methane (C₁); and

(m) withdrawing from the demethanizer a liquid enriched in hydrocarbons heavier than methane (C₂₊).

6. The process of claim 5 wherein the first flow regulating device is an expansion device.

7. The process of claim 6 wherein the expansion device is a J-T valve.

8. The process of claim 6 wherein the expansion device is a turboexpander.

9. The process of claim 5 wherein at least one of the first flow regulating device or the second flow regulating devices is a flow regulating pump.

10. The process of claim 5 wherein the second flow regulating device is an expansion device.

11. The process of claim 10 wherein the expansion device is a J-T valve.

12. The process of claim 10 wherein the expansion device is a turboexpander.

13. The process of claim 10 wherein the second flow regulating device is liquid regulator.

14. A process for separating a feed stream comprising methane (C₁), and hydrocarbons heavier than methane, and helium into a gas fraction containing substantially all the methane, a liquid fraction containing a large portion of the hydrocarbons heavier than methane, and a helium-enriched fraction, the process comprising the steps of:

(a) providing the feed stream at a temperature sufficiently low for feed stream to be multiphase;

(b) passing the multiphase feed stream of step (a) to a phase separator produce a first vapor stream and a first liquid stream;

(c) passing the first liquid stream to a first flow regulating device;

(d) passing the liquid from the first flow regulating device to a demethanizer;

(e) passing a first fraction of the first vapor stream to an expander device to lower the pressure of the first fraction, thereby cooling the first fraction of the vapor stream to produce a second multiphase stream;

(f) passing the second multiphase stream to the demethanizer;

(g) passing a second fraction of the first vapor stream to a heat exchanger to cool the second fraction of the first vapor stream to a lower temperature, thereby producing a cooled stream and passing the cooled stream to an expander device thereby producing a third multiphase stream;

(h) passing the third multiphase stream of step (g) to a separator to produce a helium-enriched vapor stream and a second liquid stream;

(i) passing the second liquid to a second flow regulating device;

(j) passing the second liquid from the second flow regulating device to the demethanizer;

(k) withdrawing a vapor stream from the demethanizer enriched in methane; and

(l) withdrawing a liquid stream from the demethanizer enriched in hydrocarbons heavier than methane.

15. The process of claim 14 wherein the first flow regulating device is an expansion device.

16. The process of claim 15 wherein the expansion device is a J-T valve.

17. The process of claim 15 wherein the expansion device is a turboexpander.

18. The process of claim 14 wherein the first flow regulating device is a cryogenic pump.

19. The process of claim 14 wherein the second flow regulating device is an expansion device.

20. The process of claim 19 wherein the expansion device is a J-T valve.

21. The process of claim 19 wherein the expansion device is a turboexpander.

22. The process of claim 14 wherein the second flow regulating device is a cryogenic pump.

23. A process for separating a feed stream comprising methane, hydrocarbons heavier than methane, and helium into a gas fraction rich in methane, a liquid fraction rich in hydrocarbons heavier than methane, and vapor fraction rich in helium, the process comprising the steps of:

(a) providing the feed stream at a temperature sufficiently low for the feed stream to be multiphase;

(b) passing the multiphase stream of step (a) to a first separator produce a first vapor stream and a first liquid stream;

(c) passing the first liquid stream to a first flow regulating device;

(d) passing the liquid stream from the first flow regulating device to a second separator to produce a first helium-enriched vapor stream and a second liquid stream;

(e) passing the second liquid stream to a second flow regulating device;

(f) passing the second liquid stream from the second flow regulating device to a demethanizer;

(g) passing a first fraction of the first vapor stream to an expansion device, thereby cooling the first fraction to produce a cooled stream;

(h) passing the cooled stream of step (g) to a third separator to produce a vapor stream and a third liquid stream;

(i) passing the third liquid stream to a third flow regulating device;

(j) passing the third liquid stream from the third flow regulating device to the demethanizer;

(k) passing a second fraction of the first vapor stream to a heat exchanger to cool the second fraction a lower temperature, and thereafter passing the cooled second fraction to an expander device to further cool the second fraction;

(l) passing the cooled second fraction from the expander device of step (k) to a fourth separator to produce a helium-enriched vapor stream and a fourth liquid stream;

(m) passing the fourth liquid stream to a fourth flow regulating device;

(n) passing fourth liquid stream to the demethanizer;

(o) withdrawing a vapor stream from the demethanizer enriched in methane;

(p) withdrawing a liquid stream from the demethanizer enriched in hydrocarbons heavier than methane.

24. The process of claim 23 wherein at least one of the first, second, third and fourth flow regulating devices is an expansion device.

25. The process of claim 24 wherein the expansion device is selected from a J-T valve or turboexpander.

26. The process of claim 23 wherein at least one of the first, second, third, and fourth flow regulating devices is a cryogenic pump.

27. A process for separation of hydrocarbons to separate a feed stream containing at least methane, a hydrocarbon less volatile than methane, and helium, into a residue gas enriched with methane and lean in the hydrocarbon less volatile than methane, a heavier fraction lean in methane and enriched with the hydrocarbon less volatile than methane, and a fraction enriched in helium, the process comprising the steps of:

(a) providing a feed stream that is partly condensed;

(b) separating the feed stream into a vapor and a first liquid;

(c) passing the liquid separated in step (b) to a first flow regulating device;

(d) passing the liquid from the flow regulating device to a distillation column;

(e) dividing the vapor obtained in step (b) into a first portion and a second portion;

(f) expanding a first portion of the vapor separated in step (b), thereby producing a second reduced pressure stream, and passing the second reduced pressure stream to the distillation column;

(g) cooling the second portion of the vapor separated in step (b) in a heat exchanger and expanding the cooled second vapor portion, thereby partly condensing the cooled second vapor portion;

(h) separating partly condensed, cooled second vapor portion of step (g) into a helium-enriched stream and a second liquid;

(i) passing the second liquid separated in step (h) to a second flow regulating device;

(j) passing second liquid from the second flow regulating device to the distillation column; and

(k) recovering from the distillation column a vapor stream enriched in methane and a liquid enriched in hydrocarbons less volatile than methane.

28. A process for separating a natural gas stream comprising methane, hydrocarbons heavier than methane, and helium into a gas fraction rich in methane, a liquid fraction rich in hydrocarbons heavier than methane, and vapor fraction rich in helium, the process comprising the steps of:

(a) providing the natural gas stream at a temperature sufficiently low for the natural gas stream to be multiphase;

(b) passing the natural gas stream of step (a) to a first phase separator to produce a first vapor stream and a first liquid stream;

(c) passing the first liquid stream to a first flow regulating device;

(d) passing the liquid stream from the first flow regulating device to a demethanizer;

(e) passing the first vapor stream to an a first heat exchanger, thereby cooling the first vapor fraction to produce second multiphase stream;

(f) passing the second multiphase stream of step (e) to a second phase separator to produce a second vapor stream and second liquid stream;

(g) passing the second liquid stream to a second flow regulating device;

(h) passing the second liquid from the second flow regulating device to the demethanizer;

(i) passing the second vapor stream to a second heat exchanger, thereby cooling the second vapor fraction to produce third multiphase stream;

(j) passing the third multiphase stream of step (i) to a third phase separator to produce a third vapor stream that is enriched in helium and a third liquid stream;

(k) passing the third liquid stream to a third flow regulating device;

(l) passing the third liquid from the third flow regulating device to the demethanizer;

(m) withdrawing a vapor stream from the demethanizer enriched in methane; and

(n) withdrawing a liquid stream from the demethanizer enriched in hydrocarbons heavier than methane.