NGL Extraction From Natural Gas

• US 20090293537A1
• Filed: 05/27/2009
• Published: 12/03/2009
• Est. Priority Date: 05/27/2008
• Status: Abandoned Application

• Current Assignee: Greg E. Ameringer
• Original Assignee: Greg E. Ameringer
• Inventors: Ameringer, Greg E.
• Application Number:
  US12/455,124
• Publication Number:
  US 20090293537A1
• Time in Patent Office: Days
• US Class Current: 62/620
• 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 2210/06 Splitting of the feed stream, e.g. for treating or cooling in different ways
• CPC Class Codes: F25J 2230/60 the fluid being hydrocarbons or a mixture of hydrocarbons
• CPC Class Codes: F25J 2240/40 Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
• 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

Abstract

A process of extraction of natural gas liquids from a hydrocarbon stream is disclosed. The recovered natural gas liquids are flashed to a vapor to provide refrigeration to the process.

Claims

1. A process for the separation of C₂+ or C₃+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

providing a first stream of hydrocarbon gas;

cooling at least a portion of the first stream of hydrocarbon gas in a first heat exchanger to form a second stream;

introducing the second stream into a distillation column;

withdrawing a third stream of vapor hydrocarbon from an upper portion of said column having a reduced content of C₂+ or C₃+ hydrocarbons as compared to the first stream;

withdrawing a fourth stream of liquid natural gas liquid (NGL) hydrocarbon from as compared to the first stream;

reducing the pressure of the fourth stream to vaporize at least a portion of the fourth stream to form a fifth stream;

passing the fifth stream through the first heat exchanger to cool the first stream of hydrocarbon gas.

2. The process of claim 1, further comprising:

passing at least a portion of the third stream through the first heat exchanger to form a sixth stream.

3. The process of claim 1, further comprising:

diverting a portion of the first stream through a second heat exchanger to provide reboiler duty to the distillation column.

4. The process of claim 1, wherein the first heat exchanger provides heat duty to a side reboiler of the distillation column.

5. The process of claim 1, wherein the distillation column is operated with a bottom temperature of 0°

F. to 350°

F. and a top temperature of −

160°

F. to 0°

F.

6. The process of claim 1, wherein the distillation column is operated at a pressure of 150 psia to 700 psia.

7. The process of claim 1, wherein a portion of the sixth stream is diverted to an upper region of the distillation column as a reflux stream.

8. The process of claim 1, wherein the process does not include a turboexpander.

9. The process of claim 1, wherein the process includes a turboexpander that expands at least a portion of the first stream.

10. The process of claim 1, wherein the vaporization of at least a portion of the fourth stream provides at least 50% of the required cooling of the process.

11. The process of claim 1, wherein the vaporization of at least a portion of the fourth stream provides at least 75% of the required cooling of the process.

12. The process of claim 1, wherein the vaporization of at least a portion of the fourth stream provides 100% of the required cooling of the process.

13. The process of claim 1, wherein the process is capable of operating at a turndown of less than 60% of plant capacity, while at least 50% of the ethane in the first stream is recovered in the fourth stream.

14. The process of claim 1, wherein the process is capable of operating at a turndown of 10% of plant capacity, while at least 50% of the ethane in the first stream is recovered in the fourth stream.

15. The process of claim 1, wherein the process is capable of operating from 5% to 100% of plant capacity, while recovering at least 60% of the ethane and at least 90% of C₃+ from the first stream in the fourth stream.

16. The process of claim 1, wherein the process is capable of operating from 10% to 100% of plant capacity, while recovering at least 85% of the ethane and at least 95% of C₃+ from the first stream in the fourth stream.

17. The process of claim 1, wherein the process operates with a reduced compression of at least 10% as compared to a comparable turboexpander process.

18. A process for the separation of natural gas liquids from a hydrocarbon-containing gas feed comprising:

providing a first stream of hydrocarbon gas;

cooling at least a portion of the first stream of hydrocarbon gas in a first heat exchanger to form a second stream;

introducing the second stream into a distillation column;

diverting a portion of the first stream through a second heat exchanger to provide reboiler duty to the distillation column;

wherein the distillation column includes a middle reboiler stream and a lower reboiler stream that are warmed by heat exchange with the second heat exchanger to provide heat duty to the distillation column;

wherein the distillation column includes a side stream that is warmed by heat exchange with the first heat exchanger to provide heat duty to the distillation column;

withdrawing a third stream of vapor hydrocarbon from an upper portion of said column having a reduced content of C₂+ or C₃+ hydrocarbons as compared to the first stream;

passing at least a portion of the third stream through the first heat exchanger to form a sixth stream;

withdrawing a fourth stream of liquid natural gas liquid (NGL) hydrocarbon from a lower portion of said column having an increased content of C₂+ or C₃+ hydrocarbons as compared to the first stream;

reducing the pressure of the fourth stream to vaporize at least a portion of the fourth stream to form a fifth stream;

passing the fifth stream through the first heat exchanger to cool the first stream of hydrocarbon gas;

wherein the process does not include a turboexpander and the distillation column is operated with a bottom temperature of 0°

F. to 350°

F., a top temperature of −

160°

F. to 0°

F. and a pressure of 150 psia to 700 psia;

wherein the vaporization of at least a portion of the fourth stream provides at least 75% of the required cooling of the process; and

wherein the process is capable of operating from 5% to 100% of plant capacity, while recovering at least 85% of the ethane and at least 95% of C₃+ from the first stream in the fourth stream.

19. The process of claim 18, wherein a portion of the sixth stream is diverted to an upper region of the distillation column as a reflux stream.

20. The process of claim 18, wherein the process operates with a reduced compression of at least 10% as compared to a comparable turboexpander process.