Liquefaction method and system

• US 8,656,733 B2
• Filed: 02/27/2013
• Issued: 02/25/2014
• Est. Priority Date: 11/18/2008
• Status: Active Grant

• Current Assignee: HERCULES PROJECT COMPANY LLC
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Roberts, Mark Julian, Brostow, Adam Adrian
• Primary Examiner(s): Ciric, Ljiljana
• Assistant Examiner(s): COX, ALEXIS K
• Application Number:
  US13/778,772
• Publication Number:
  US 20130174603A1
• Time in Patent Office: 363 Days
• Field of Search: 626/11, 626/12, 626/06, 626/14, 626/23
• US Class Current: 62/611
• 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 1/005 by expansion of a gaseous refrigerant stream with extraction of work
• CPC Class Codes: F25J 1/0052 by vaporising a liquid refrigerant stream
• CPC Class Codes: F25J 1/0072 Nitrogen
• CPC Class Codes: F25J 1/0087 Propane; Propylene
• CPC Class Codes: F25J 1/009 Hydrocarbons with four or more carbon atoms
• CPC Class Codes: F25J 1/0095 Oxides of carbon, e.g. CO2
• CPC Class Codes: F25J 1/0097 Others, e.g. F-, Cl-, HF-, HClF-, HCl-hydrocarbons etc. or mixtures thereof
• CPC Class Codes: F25J 1/0204 as a single flow SCR cycle
• CPC Class Codes: F25J 1/0205 as a dual level SCR refrigeration cascade
• CPC Class Codes: F25J 1/0254 controlling particular process parameter, e.g. pressure, temperature
• CPC Class Codes: F25J 1/0263 using different types of heat exchangers
• CPC Class Codes: F25J 1/0265 comprising cores associated exclusively with the cooling of a refrigerant stream, e.g. for auto-refrigeration or economizer
• CPC Class Codes: F25J 1/0267 using flash gas as heat sink
• CPC Class Codes: F25J 1/0268 using a dedicated refrigeration means F25J1/0296 takes precedence
• CPC Class Codes: F25J 1/0283 Gas turbine as the prime mechanical driver
• CPC Class Codes: F25J 1/0284 Electrical motor as the prime mechanical driver
• CPC Class Codes: F25J 1/0288 using work extraction by mechanical coupling of compression and expansion of the refrigerant, so-called companders
• CPC Class Codes: F25J 1/0292 Refrigerant compression by cold or cryogenic suction of the refrigerant gas
• CPC Class Codes: F25J 1/0294 : Multiple compressor casings/strings in parallel, e.g. split arrangement
• CPC Class Codes: F25J 2220/62 : Separating low boiling components, e.g. He, H2, N2, Air
• CPC Class Codes: F25J 2230/08 : Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler
• CPC Class Codes: F25J 2230/32 : Compression of the product stream
• CPC Class Codes: F25J 2270/16 : with mutliple gas expansion loops of the same refrigerant
• CPC Class Codes: F25J 2290/62 : Details of storing a fluid in a tank

Abstract

Liquefaction using a closed loop refrigeration system, including compressing a gaseous refrigerant stream; cooling at least a portion of the compressed gaseous refrigerant stream in a first heat exchanger; expanding a first portion of the cooled, compressed gaseous refrigerant stream from the first heat exchanger to provide a first expanded gaseous refrigerant stream; cooling and substantially liquefying a feed gas stream to form a substantially liquefied feed gas stream in a second heat exchanger through indirect heat exchange against the first portion of the first expanded gaseous refrigerant stream; and further cooling a second portion of the cooled, compressed gaseous refrigerant stream from the first heat exchanger in a third heat exchanger by indirect heat exchange with a second portion of the first expanded gaseous refrigerant stream, wherein the first expanded gaseous refrigerant stream exiting the first expander is substantially vapor.

Claims

1. A method of liquefaction using a closed loop refrigeration system, the method comprising the steps of:

(a) compressing a gaseous refrigerant stream in at least one compressor;

(b) cooling at least a portion of the compressed gaseous refrigerant stream in a first heat exchanger;

(c) expanding a first portion of the cooled, compressed gaseous refrigerant stream from the first heat exchanger in a first expander to provide a first expanded gaseous refrigerant stream;

(d) cooling and substantially liquefying a feed gas stream to form a substantially liquefied feed gas stream in a second heat exchanger through indirect heat exchange against the first portion of the first expanded gaseous refrigerant stream from the first expander; and

(e) further cooling a second portion of the cooled, compressed gaseous refrigerant stream from the first heat exchanger in a third heat exchanger by indirect heat exchange with a second portion of the first expanded gaseous refrigerant stream from the first expander,

wherein the first expanded gaseous refrigerant stream exiting the first expander is substantially vapor.

2. The method of claim 1, further comprising subcooling the cooled and substantially liquefied feed gas stream through indirect heat exchange in a subcooler exchanger against a second expanded gaseous refrigerant stream exiting a second expander.

3. The method of claim 2, wherein the second portion of the cooled, compressed gaseous refrigerant stream, after being further cooled in the third heat exchanger, is fed to the second expander to provide the second expanded gaseous refrigerant stream.

4. The method of claim 3, wherein the second expanded gaseous refrigerant stream exiting the second expander is substantially vapor.

5. The method of claim 4, wherein the second expanded gaseous refrigerant stream exiting the subcooler exchanger is compressed in a low pressure compressor;

combined with the first portion of the first expanded gaseous refrigerant stream exiting the second heat exchanger and the second portion of the first expanded gaseous refrigerant stream exiting the third heat exchanger; and

the mixed stream further compressed in a high pressure compressor.

6. The method of claim 1, further comprising warming at least a portion of the first portion of the first expanded gaseous refrigerant stream exiting the second heat exchanger in the first heat exchanger.

7. The method of claim 1, further comprising warming the second portion of the first expanded gaseous refrigerant stream exiting the third heat exchanger in the first heat exchanger.

8. The method of claim 1, further comprising splitting the compressed gaseous refrigerant stream exiting the at least one compressor into a first portion and a second portion, cooling said first portion in a supplemental refrigeration system that comprises at least one stage of a vaporizing liquid refrigerant, cooling said second portion in the first heat exchanger in step (b) of claim 1, and combining the cooled first portion with a portion of the cooled second portion for expansion in the first expander in step (c) of claim 1.

9. The method of claim 1, further comprising splitting the compressed gaseous refrigerant stream exiting the at least one compressor into a first portion and a second portion, expanding said first portion in a third expander, warming the resultant expanded first portion in the first heat exchanger, and cooling said second portion in the first heat exchanger in step (b) of claim 1.

10. The method of claim 1, wherein the feed gas stream for liquefaction is a natural gas stream.

11. The method of claim 1, wherein the gaseous refrigerant stream is a nitrogen stream.

12. A closed loop system for liquefaction comprising:

a refrigeration circuit, the refrigeration circuit comprising;

a first compressor;

A first heat exchanger fluidly coupled to the first compressor and adapted to accept a gaseous refrigerant stream from the first compressor;

a first expander fluidly coupled to the first heat exchanger and adapted to accept a first stream of refrigerant from the first heat exchanger;

a second heat exchanger fluidly coupled to the first expander and adapted to accept a first expanded gaseous refrigerant stream from the first expander and a feed gas stream;

a third heat exchanger fluidly coupled to the first heat exchanger and to the first expander and adapted to accept a second stream of refrigerant from the first heat exchanger and a second expanded gaseous refrigerant stream from the first expander;

a second expander fluidly coupled to the third heat exchanger and adapted to accept a stream of refrigerant from the third heat exchanger; and

a subcooler exchanger fluidly coupled to the second heat exchanger and the second expander and adapted for acceptance of the feed gas stream from the second heat exchanger and an expanded gaseous refrigerant stream from the second expander,

wherein the first heat exchanger and the third heat exchanger may be combined into one heat exchanger, and

wherein the second heat exchanger and the subcooler exchanger may be combined into one heat exchanger.

13. A method of liquefaction using a closed loop refrigeration system, the method comprising the steps of:

(a) compressing a gaseous refrigerant stream in at least one compressor;

(b) cooling at least a portion of the compressed gaseous refrigerant stream in a first heat exchanger;

(c) removing from an intermediate section of the first heat exchanger a cooled, compressed gaseous refrigerant stream and expanding said portion of the cooled, compressed gaseous refrigerant stream from the first heat exchanger in a first expander to provide a first expanded gaseous refrigerant stream;

(d) cooling and substantially liquefying a feed gas stream to form a substantially liquefied feed gas stream in a second heat exchanger through indirect heat exchange against the first portion of the first expanded gaseous refrigerant stream from the first expander; and

(e) further cooling a second portion of the cooled, compressed gaseous refrigerant stream in the first heat exchanger by indirect heat exchange with a second portion of the first expanded gaseous refrigerant stream from the first expander,

wherein the first expanded gaseous refrigerant stream exiting the first expander is substantially vapor.

14. The method of claim 13, further comprising subcooling the cooled and substantially liquefied feed gas stream through indirect heat exchange in the second exchanger against a second expanded gaseous refrigerant stream exiting a second expander.

15. The method of claim 14, wherein the second portion of the cooled, compressed gaseous refrigerant stream, after being further cooled in the first heat exchanger, is fed to the second expander to provide the second expanded gaseous refrigerant stream.

16. The method of claim 15, wherein the second expanded gaseous refrigerant stream exiting the second expander is substantially vapor.

17. The method of claim 13, further comprising subcooling the cooled and substantially liquefied feed gas stream through indirect heat exchange in a subcooler exchanger against a second expanded gaseous refrigerant stream exiting a second expander.

18. The method of claim 13, wherein the feed gas stream for liquefaction is a natural gas stream.

19. The method of claim 13, wherein the gaseous refrigerant stream is a nitrogen stream.

20. A closed loop system for liquefaction, comprising:

a refrigeration circuit, the refrigeration circuit comprising;

a first compressor;

a first heat exchanger fluidly coupled to the first compressor and adapted to accept a compressed gaseous refrigerant stream from the first compressor;

a first expander fluidly coupled to the first heat exchanger and adapted to accept a first portion of the cooled, compressed gaseous refrigerant stream from an intermediate location of the first heat exchanger;

a second heat exchanger fluidly coupled to the first expander and adapted to accept a first expanded gaseous refrigerant stream from the first expander and a feed gas stream;

a second expander fluidly coupled to the first heat exchanger and adapted to accept a second portion of the cooled, compressed gaseous refrigerant stream from the first heat exchanger;

wherein the first heat exchanger is adapted to accept a second expanded gaseous refrigerant stream from the first expander, and wherein the second heat exchanger is adapted to receive an expanded gaseous refrigerant stream from the second expander.