Vertical heat exchanger configuration for LNG facility

• US 20060086140A1
• Filed: 10/25/2004
• Published: 04/27/2006
• Est. Priority Date: 10/25/2004
• Status: Active Grant

• Current Assignee: Conocophillips Company (ConocoPhillips)
• Original Assignee: Conocophillips Company (ConocoPhillips)
• Inventors: Eaton, Anthony P., Martinez, Bobby D., Christian, Michael
• Granted Patent: US 7,266,976 B2
• Time in Patent Office: Days
• US Class Current: 62/612
• CPC Class Codes: F25J 1/0022 Hydrocarbons, e.g. natural gas
• CPC Class Codes: F25J 1/004 by flash gas recovery F25J1/0267 takes precedence
• CPC Class Codes: F25J 1/0052 by vaporising a liquid refrigerant stream
• CPC Class Codes: F25J 1/0085 Ethane; Ethylene
• CPC Class Codes: F25J 1/0087 Propane; Propylene
• CPC Class Codes: F25J 1/021 using a deep flash recycle loop
• CPC Class Codes: F25J 1/0258 vertical layout of the equipments within in the cold box
• CPC Class Codes: F25J 1/0259 Modularity and arrangement of parts of the liquefaction unit and in particular of the cold box, e.g. pre-fabrication, assembling and erection, dimensions, horizontal layout "plot"
• CPC Class Codes: F25J 1/0262 Details of the cold heat exchange system constructional details F25J5/00, construction of cold-exchangers in general F28
• CPC Class Codes: F25J 1/0264 Arrangement of heat exchanger cores in parallel with different functions, e.g. different cooling streams F25J1/0272 takes precedence
• CPC Class Codes: F25J 2210/06 Splitting of the feed stream, e.g. for treating or cooling in different ways
• CPC Class Codes: F25J 2220/64 Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general
• CPC Class Codes: F25J 2250/02 Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
• CPC Class Codes: F25J 2250/20 Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams
• CPC Class Codes: F25J 2290/40 Vertical layout or arrangement of cold equipments within in the cold box, e.g. columns, condensers, heat exchangers etc.
• CPC Class Codes: F25J 5/005 in a reboiler-condenser, e.g. within a column

Abstract

LNG facility employing one or more vertical core-in-kettle heat exchangers to cool natural gas via indirect heat exchange with a refrigerant. The vertical core-in-kettle heat exchangers save plot space and can be use to reduce the size of cold boxes employed in the LNG facility. In addition, vertical core-in-kettle heat exchangers can exhibit enhanced heat transfer efficiency due to improved refrigerant access to the core, improved refrigerant circulation around the core, and/or improved vapor/liquid disengagement above the core.

Claims

1. A method of transferring heat from a refrigerant to a cooled fluid, said method comprising:

(a) introducing the refrigerant into an internal volume defined within a shell, said internal volume having a height-to-width ratio greater than 1;

(b) introducing the cooled fluid into a plate-fin core disposed within the internal volume of the shell; and

(c) transferring heat from the cooled fluid in the core to the refrigerant in the shell via indirect heat exchange.

2. The method according to claim 1,

said height-to-width ratio being at least about 1.25.

3. The method according to claim 1,

step (c) including vaporizing at least a portion of said refrigerant.

4. The method according to claim 3,

said vaporizing of step (c) causing a thermosiphon effect in the core.

5. The method according to claim 1;

and

(d) maintaining the level of liquid-phase refrigerant in said shell at an elevation where at least 50% of the height of the core is submerged in the liquid-phase refrigerant.

6. The method according to claim 5,

step(d) including maintaining the level of liquid-phase refrigerant in the shell at an elevation where 75-95% of the height of the core is submerged in the liquid-phase refrigerant.

7. The method according to claim 6,

step (a) including introducing said refrigerant into the internal volume at a location above the level of liquid-phase refrigerant in the shell.

8. The method according to claim 1;

and

(e) removing a gas-phase refrigerant from an upper outlet of the shell; and

(f) removing a liquid-phase refrigerant from a lower outlet of the shell.

9. The method according to claim 1,

said shell including a substantially cylindrical sidewall extending along a central sidewall axis,

said sidewall axis being substantially upright.

10. The method according to claim 9,

said height-to-width ratio being at least about 1.25.

11. The method according to claim 9,

said core defining a plurality of core-side passageways for receiving the cooled fluid,

said core defining a plurality of shell-side passageways for receiving the refrigerant,

each of said shell-side passageways extending generally upwardly between a lower refrigerant inlet and an upper refrigerant outlet.

12. The method according to claim 11,

step (c) including vaporizing at least a portion of the refrigerant in the shell-side passageways.

13. The method according to claim 12,

said vaporizing causing natural upward convection of the refrigerant through the shell-side passageways.

14. The method according to claim 1,

said core being spaced from the top, bottom, and sides of the shell.

15. The method according to claim 1,

said internal volume having a maximum height (H),

said core being spaced from the bottom of the internal volume by at least 0.2 H,

said core being spaced from the top of the internal volume by at least 0.2 H.

16. The method according to claim 1,

said cooled fluid comprising predominantly methane,

said refrigerant comprising predominantly propane, propylene, ethane, ethylene, methane, or carbon dioxide.

17. The method according to claim 1,

said cooled fluid being a natural gas stream,

said refrigerant comprising predominantly propane or ethylene.

18. A process for liquefying a natural gas stream, said process comprising:

(a) cooling the natural gas stream via indirect heat exchange with a first refrigerant comprising predominantly propane or propylene; and

(b) further cooling the natural gas stream via indirect heat exchange with a second refrigerant comprising predominantly ethane or ethylene,

at least a portion of said cooling of steps (a) and/or (b) being carried out in at least one vertical core-in-kettle heat exchanger.

19. The process according to claim 18,

said core-in-kettle heat exchanger comprising a shell and a plate-fin core received in the shell,

said shell comprising a substantially cylindrical sidewall extending along a central sidewall axis,

said heat exchanger being positioned so that the sidewall axis has a substantially upright orientation.

20. The process according to claim 19,

said core defining a plurality of generally upwardly extending core-side passageways and a plurality of generally upwardly extending shell-side passageways,

said natural gas stream being received in the core-side passageways,

said first or second refrigerant being received in the shell-side passageways.

21. The process according to claim 20,

said core defining alternating core-side and shell-side passageways.

22. The process according to claim 20,

said cooling of steps (a) and/or (b) including causing at least a portion of the first refrigerant in the shell-side passageways to vaporize, thereby providing a thermosiphon effect.

23. The process according to claim 19,

said shell defining an internal volume having a maximum height (H),

said core being spaced from the top of the internal volume by at least 0.2 H,

said core being spaced from the bottom of the internal volume by at least 0.2 H.

24. The process according to claim 23,

said core being spaced from the sidewall of the shell.

25. The process according to claim 18;

and

(c) further cooling the natural gas stream via indirect heat exchange with a third refrigerant comprising predominantly methane.

26. The process according to claim 25;

and

(d) flashing at least a portion of the natural gas stream to thereby provide gas-phase natural gas,

step (c) including using at least a portion of the gas-phase natural gas as the third refrigerant.

27. The process according to claim 26,

said first refrigerant comprising predominantly propane,

said second refrigerant comprising predominantly ethylene.

28. The process according to claim 18;

and

(e) vaporizing liquified natural gas produced by the precess of steps (a) and (b).

29. A liquified natural gas product produced by the process of claim 18.

30. A computer simulation process comprising using a computer to simulate the process of claim 18.

31. A heat exchanger comprising:

a shell defining an internal volume; and

at least one core disposed in the internal volume,

said shell comprising a substantially cylindrical sidewall, a normally-upper end cap, and a normally-lower end cap, said upper and lower end caps being disposed on generally opposite ends of the sidewall,

said sidewall defining a fluid inlet for receiving a shell-side fluid into the internal volume,

said normally-upper end cap defining a vapor outlet for discharging gas-phase shell-side fluid from the internal volume,

said normally-lower end cap defining a liquid outlet for discharging liquid-phase shell-side fluid from the internal volume.

32. The heat exchanger according to claim 31,

said core being a plate-fin core.

33. The heat exchanger according to claim 31,

said internal volume having a maximum height (H) and a maximum width (W),

said internal volume having a H/W ratio greater than 1.

34. The heat exchanger according to claim 33,

said core being spaced from the top and bottom of said internal volume by at least 0.2 H.

35. The heat exchanger according to claim 33,

said fluid inlet being spaced from the top and bottom of said internal volume by at least 0.3 H.

36. The heat exchanger according to claim 33,

said core having a maximum height (h),

said core and shell having a h/H ratio of less than 0.75.

37. The heat exchanger according to claim 36,

said h/H ratio being 0.25-0.5.

38. The heat exchanger according to claim 33,

said core having a minimum width (w),

said core and shell having a w/W ratio less than 0.95.

39. The heat exchanger according to claim 31,

said sidewall extending along a central sidewall axis,

said core providing for counter-current heat exchange between two fluids flowing substantially parallel to the direction of extension of the central sidewall axis.

40. The heat exchanger according to claim 39,

said core defining a plurality of core-side passageways and a plurality of shell-side passageways,

said core-side and shell-side passageways being fluidly isolated from one another,

said shell-side passageways presenting a normally-lower inlet and a normally-upper outlet,

said shell-side passageways extending from the normally-lower inlet to the normally-upper outlet.

41. The heat exchanger according to claim 40,

said core-side and shell-side passageways extending substantially parallel to the direction of extension of the sidewall axis.

42. The heat exchanger according to claim 31,

said core being a brazed-aluminum, plate-fin core.

43. A heat exchanger comprising:

a shell defining an internal volume, said shell comprising a substantially cylindrical sidewall extending along a central sidewall axis; and

a core disposed in the shell,

said core defining a plurality of core-side passageways and a plurality of shell-side passageways, said core-side passageways being fluidly isolated from the internal volume of the shell,

said shell-side passageways presenting opposite open ends that provide fluid communication with the internal volume of the shell,

said shell-side passageways extending in a direction that is substantially parallel to the direction of extension of the sidewall axis so that a thermosiphon effect can be created in the shell-side passageways when the heat exchanger is positioned with the sidewall axis in a substantially upright orientation.

44. The heat exchanger according to claim 43,

said plurality of shell-side passageways being open only at the ends so that any fluid entering the shell-side passageways must enter through one of the ends.

45. The heat exchanger according to claim 43,

said core being a plate-fin core.

46. The heat exchanger according to claim 43,

said core being a brazed-aluminum, plate-fin core.

47. The heat exchanger according to claim 43,

said internal volume having a maximum height (H) measured along the sidewall axis and a maximum width (W) measured perpendicular to the sidewall axis,

said internal volume having a H/W ratio greater than 1.

48. The heat exchanger according to claim 47,

said shell including a normally-upper end cap and a normally-lower end cap,

said maximum height (H) being measured between the end caps,

said core presenting a normally-upper end that is spaced from the normally-upper end cap by a first maximum distance of at least 0.2 H,

said core presenting a normally-lower end that is spaced from the normally-lower end cap by a second maximum distance of at least 0.2 H,

said first and second maximum distances being measured substantially parallel to the direction of extension of the sidewall axis.

49. The heat exchanger according to claim 48,

said first and second maximum distances being at least 2 feet.

50. The heat exchanger according to claim 47,

said core having a maximum height (h) measured along the sidewall axis,

said core and shell having a h/H ratio less than 0.75.

51. The heat exchanger according to claim 43,

said shell including an inlet, a first outlet, and a second outlet, each communicating with the internal volume of the shell,

said first and second outlets being spaced from one another along the sidewall axis,

said first and second outlets being disposed on generally opposite ends of the shell.

52. The heat exchanger according to claim 51,

said inlet being formed in the sidewall.

53. A core-in-kettle heat exchanger system comprising:

a shell comprising a substantially cylindrical sidewall extending along a central sidewall axis;

a plate-fin core disposed in the shell; and

a support structure configured to support the shell in a vertical configuration where the sidewall axis is substantially upright.

54. The system according to claim 53,

said core being a brazed-aluminum, plate-fin core.

55. The system according to claim 53,

said shell defining an internal volume within which the core is disposed,

said internal volume having a maximum height (H) measured along the sidewall axis and a maximum width (W) measured perpendicular to the sidewall axis,

said internal volume having a H/W ratio greater than 1.

56. The system according to claim 55,

said shell including a normally-upper end cap and a normally-lower end cap,

said maximum height (H) being measured between the end caps,

said core presenting a normally-upper end that is spaced from the normally-upper end cap by a first maximum distance of at least 0.2 H,

said core presenting a normally-lower end that is spaced from the normally-lower end cap by a second maximum distance of at least 0.2 H,

said first and second maximum distances being measured substantially parallel to the direction of extension of the sidewall axis.

57. A system according to claim 56,

said first and second maximum distances being at least 2 feet.

58. A system according to claim 55,

said core having a maximum height (h) measured along the sidewall axis,

said core and shell having a h/H ratio less than 0.75.

59. A system according to claim 55,

said shell including an inlet, a first outlet, and a second outlet, each communicating with the internal volume of the shell,

said first and second outlets being spaced from one another along the sidewall axis,

said first and second outlets being disposed on generally opposite ends of the shell.

60. A system according to claim 59,

said inlet being formed in the sidewall.

61. An apparatus comprising:

a cold box defining an internal volume; and

a plurality of vertical core-in-kettle heat exchangers disposed in the internal volume.

62. The apparatus according to claim 61;

and

a substantially loose insulation material disposed in the internal volume of the cold box and substantially surrounding the core-in-kettle heat exchangers.

63. The apparatus according to claim 62;

and

said insulation material comprising perlite.

64. The apparatus according to claim 61,

said cold box defining a purge gas inlet and a purge gas outlet,

said cold box being substantially fluid-tight except for the purge gas inlet and outlet.

65. The apparatus according to claim 64;

and

a hydrocarbon monitor operable to detect the presence of hydrocarbons,

said hydrocarbon monitor being disposed in fluid communication with the purged gas outlet.

66. A liquefied natural gas facility for cooling a natural gas feed stream by indirect heat exchange with one or more refrigerants, said liquefied natural gas facility comprising:

a first refrigeration cycle for cooling the natural gas stream via indirect heat exchange with a first refrigerant,

said first refrigeration cycle comprising a first vertical core-in-kettle heat exchanger,

said first vertical core-in-kettle heat exchanger defining a kettle-side volume and a core-side volume fluidly isolated from one another,

said kettle-side volume being configured to receive the first refrigerant,

said core-side volume being configured to receive the natural gas stream.

67. The facility according to claim 66,

said first refrigerant comprising predominantly propane, propylene, ethane, ethylene, or carbon dioxide.

68. The facility according to claim 66,

said first refrigerant comprising predominantly ethylene.

69. The facility according to claim 66,

said first refrigeration cycle employing a plurality of vertical core-in-kettle heat exchangers to sequentially cool the natural gas stream via indirect heat exchange with the first refrigerant.

70. The facility according to claim 69,

said first refrigeration cycle comprising a cold box receiving said plurality of vertical core-in-kettle heat exchangers.

71. The facility according to claim 66;

and

a second refrigeration cycle for cooling the natural gas stream via indirect heat exchange with a second refrigerant of different composition than the first refrigerant.

72. The facility according to claim 71,

said second refrigerant comprising predominantly propane, propylene, ethane, ethylene, or carbon dioxide.

73. The facility according to claim 71,

said first refrigerant comprising predominantly ethylene,

said second refrigerant comprising predominantly propane.

74. The facility according to claim 73,

said second refrigeration cycle being located upstream of the first refrigeration cycle.

75. The facility according to claim 71,

said second refrigeration cycle comprising a second vertical core-in-kettle heat exchanger.

76. The facility according to claim 71, and

an open methane refrigeration cycle disposed downstream of the first and second refrigeration cycles.