APPARATUS FOR THE LIQUEFACTION OF GAS AND METHODS RELATING TO SAME

• US 20070107465A1
• Filed: 11/16/2006
• Published: 05/17/2007
• Est. Priority Date: 05/04/2001
• Status: Abandoned Application

• Current Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Original Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Inventors: Turner, Terry, Wilding, Bruce, McKellar, Michael, Bingham, Dennis, Hoffman, Lisa
• Application Number:
  US11/560,682
• Publication Number:
  US 20070107465A1
• Time in Patent Office: Days
• US Class Current: 62/613
• CPC Class Codes: F25J 1/0022 Hydrocarbons, e.g. natural gas
• CPC Class Codes: F25J 1/0037 of a return stream
• CPC Class Codes: F25J 1/004 by flash gas recovery F25J1/0267 takes precedence
• CPC Class Codes: F25J 1/0045 by vaporising a liquid return stream
• CPC Class Codes: F25J 1/0201 using only internal refrigeration means, i.e. without external refrigeration
• CPC Class Codes: F25J 1/0202 in a quasi-closed internal refrigeration loop F25J1/0208, F25J1/0219, F25J1/0224 take precedence
• CPC Class Codes: F25J 1/0204 as a single flow SCR cycle
• CPC Class Codes: F25J 1/0212 as a single flow MCR cycle
• CPC Class Codes: F25J 1/0232 integration within a pressure letdown station of a high pressure pipeline system
• CPC Class Codes: F25J 1/0247 start-up of the process
• CPC Class Codes: F25J 1/0251 Intermittent or alternating process, so-called batch process, e.g. "peak-shaving"
• CPC Class Codes: F25J 1/0275 adapted for special use of the liquefaction unit, e.g. portable or transportable devices
• CPC Class Codes: F25J 2205/20 using solidification of components
• CPC Class Codes: F25J 2205/60 using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
• CPC Class Codes: F25J 2205/84 using filter
• CPC Class Codes: F25J 2210/06 Splitting of the feed stream, e.g. for treating or cooling in different ways
• CPC Class Codes: F25J 2215/60 Methane
• CPC Class Codes: F25J 2220/62 Separating low boiling components, e.g. He, H2, N2, Air
• CPC Class Codes: F25J 2220/66 Separating acid gases, e.g. CO2, SO2, H2S or RSH
• CPC Class Codes: F25J 2220/68 Separating water or hydrates
• CPC Class Codes: F25J 2230/60 : the fluid being hydrocarbons or a mixture of hydrocarbons
• CPC Class Codes: F25J 2270/04 : Internal refrigeration with work-producing gas expansion loop
• CPC Class Codes: F25J 2280/02 : Control in general, load changes, different modes ("runs"), measurements
• CPC Class Codes: F25J 2290/62 : Details of storing a fluid in a tank
• CPC Class Codes: F25J 3/08 : Separating gaseous impurities from gases or gaseous mixtures or from liquefied gases or liquefied gaseous mixturescold traps B01D8/00

Abstract

An apparatus, a system and a method for producing liquefied gas are provided. A liquefaction plant may be coupled to a source of, for example, unpurified natural gas, such as a natural gas pipeline at a pressure letdown station. A portion of the gas is drawn off and split into a process stream and a cooling stream. The cooling stream may pass through an expansion device. The compressed process stream is cooled, such as by a heat exchange process utilizing the expanded cooling stream, by a heat exchanger utilizing a separate, independent refrigerant, or by both. The cooled, compressed process stream is expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. A portion of the liquid gas may be used for additional cooling or substantially all of the liquid gas may be collected as product.

Claims

1. A method of producing liquid natural gas, the method comprising:

providing a source of unpurified natural gas and flowing a portion of the natural gas from the source;

dividing the portion of natural gas into at least a process stream and a cooling stream;

flowing the process stream sequentially through a compressor and a first side of at least one heat exchanger,

flowing at least a portion of the process stream from the at least one heat exchanger through at least one expansion device and into a liquid-gas separator;

flowing the cooling stream sequentially through an expander and a second side of the at least one heat exchanger;

flowing a refrigerant in a heat exchange relationship with the process stream at a location of flow between the compressor and the liquid-gas separator; and

maintaining the refrigerant separate from the process stream and the cooling stream.

2. The method according to claim 1, wherein flowing at least a portion of the process stream from the at least one heat exchanger through an expansion device and into a liquid-gas separator further includes flowing the at least a portion of the process stream sequentially from the at least one heat exchanger through the first side of a second heat exchanger, through the at least one expansion device and into the liquid-gas separator.

3. The method according to claim 2, wherein flowing a refrigerant in a heat exchange relationship with the process stream at a location of flow between the compressor and the liquid-gas separator further includes flowing the refrigerant through the second side of the second heat exchanger.

4. The method according to claim 3, wherein flowing the at least a portion of the process stream through an expansion device includes flowing the at least a portion of the process stream through at least two expansion valves.

5. The method according to claim 4, further comprising arranging the at least two expansion valves in a parallel flow configuration.

6. The method according to claim 5, further comprising configuring a first expansion valve of the at least two expansion valves to exhibit a first flow capacity (Cv) and configuring a second valve of the at least two expansion valves to exhibit a second Cv, different from the first Cv.

7. The method according to claim 6, further comprising flowing approximately 80% of the at least a portion of the process stream through the first expansion valve of the at least two expansion valves.

8. The method according to claim 7, further comprising flowing the remainder of the at least a portion of the process stream through the second expansion valve of the at least two expansion valves.

9. The method according to claim 1, further comprising producing a slurry of liquid natural gas and solid carbon dioxide from the at least a portion of the process stream within the liquid-gas separator.

10. The method according to claim 9, further comprising agitating the slurry to keep the solid carbon dioxide substantially suspended within the liquid natural gas.

11. The method according to claim 10, wherein agitating the slurry further includes bubbling a gas through the slurry.

12. The method according to claim 11, further comprising transferring at least a portion of the slurry from the liquid-gas separator to at least one transfer tank.

13. The method according to claim 12, wherein transferring at least a portion of the slurry from the liquid-gas separator to at least one transfer tank further comprises selectively transferring at least a portion of the slurry from the liquid-gas separator to a plurality of transfer tanks.

14. The method according to claim 13, further comprising flowing the at least a portion of the slurry from at least one of the plurality of transfer tanks to at least one hydrocyclone.

15. The method according to claim 14, wherein flowing the at least a portion of the slurry from at least one of the plurality of transfer tanks to at least one hydrocyclone further comprises selectively flowing the at least a portion of slurry from at least one of the plurality of transfer tanks to a plurality of hydrocyclones.

16. The method according to claim 15, further comprising flowing a slush that is rich in solid carbon dioxide through an underflow of the at least one hydrocyclone to a sublimation tank.

17. The method according to claim 16, further comprising subliming the solid carbon dioxide to a gas.

18. The method according to claim 14, further comprising flowing liquid natural gas through an overflow of the hydrocyclone to a storage tank.

19. The method according to claim 18, further comprising flowing the liquid natural gas through at least one filter prior to flowing the liquid natural gas to the storage tank.

20. The method according to claim 19, further comprising flowing at least a portion of the cooling stream back into the source of unpurified natural gas.

21. The method according to claim 20, further comprising compressing the at least a portion of the cooling stream prior to flowing it into the source of unpurified natural gas.

22. The method according to claim 20, further comprising recirculating at least a portion of the cooling stream back into at least one of the cooling stream and the process stream.

23. The method according to claim 22, further comprising compressing the at least a portion of the cooling stream prior to recirculating it into at least one the cooling stream and the process stream.

24. The method according to claim 1, further comprising compressing the portion of the natural gas flowed from the source prior to dividing the portion of natural gas into at least a process stream and a cooling stream.

25. The method according to claim 1, wherein flowing at least a portion of the process stream sequentially from the at least one heat exchanger through the first side of a second heat exchanger, through an expansion device and into a liquid-gas separator includes flowing substantially all of the process stream sequentially from the at least one heat exchanger through the first side of a second heat exchanger, through the at least one expansion device and into the liquid-gas separator.

26. The method according to claim 25, further comprising producing a slurry of liquid natural gas and solid carbon dioxide from the at least a portion of the process stream within the liquid-gas separator.

27. The method according to claim 26, further comprising separating a vapor component from the slurry.

28. The method according to claim 27, further comprising substantially separating the liquid natural gas from the solid carbon dioxide.

29. The method according to claim 28, further comprising collecting and storing substantially all of the separated, liquid natural gas.

30. A liquefaction plant comprising:

a compressor;

a first expansion device;

a first heat exchanger;

at least a second expansion device;

a gas-liquid separator;

a first flow path defined and configured for sequential delivery of a first stream of gas through the compressor and a first side of the first heat exchanger;

a second flow path defined and configured for sequential delivery of a second stream of gas through the first expansion device and a second side of the first heat exchanger;

at least one additional flow path defined and configured for delivery of at least a portion of the first stream of gas from the first heat exchanger through the at least a second expansion device and into the gas-liquid separator; and

a refrigerant loop configured to flow a refrigerant stream in a heat exchange relationship with the first stream, wherein the refrigerant stream remains separate from the first stream and the second stream.

31. The liquefaction plant of claim 30, further comprising at least a second heat exchanger, and wherein the at least one additional flow path is defined and configured for sequential delivery of the at least a portion of the first stream of gas from the first heat exchanger through the first side of the second heat exchanger, through the at least a second expansion device and into the gas-liquid separator.

32. The liquefaction plant of claim 31, wherein the refrigerant loop is configured to flow the refrigerant stream through a second side of the second heat exchanger.

33. The liquefaction plant of claim 32, further comprising at least one transfer tank located and configured to receive a solid-liquid slurry from the gas-liquid separator.

34. The liquefaction plant of claim 33, wherein the at least one transfer tank includes at least two transfer tanks which are in selective communication with the gas-liquid separator.

35. The liquefaction plant of claim 33, further comprising at least one hydrocyclone in selective communication with the at least one transfer tank.

36. The liquefaction plant of claim 35, further comprising a storage tank in communication with an overflow of the at least one hydrocyclone.

37. The liquefaction plant of claim 36, wherein the at least one hydrocyclone includes at least two hydrocyclones and wherein the storage tank is in selective communication with each of the at least two hydrocyclones.

38. The liquefaction pant of claim 36, further comprising at least one filter disposed in a flow path between the at least one hydrocyclone and the storage tank.

39. The liquefaction plant of claim 38, further comprising a sublimation tank in communication with an underflow of the at least one hydrocyclone.

40. The liquefaction plant of claim 32, further comprising a recompression compressor configured to receive a flow of gas from the second side of the first heat exchanger.

41. The liquefaction plant of claim 40, further comprising a further flow path extending from the recompression compressor to an exit of the plant.