METHODS OF NATURAL GAS LIQUEFACTION AND NATURAL GAS LIQUEFACTION PLANTS UTILIZING MULTIPLE AND VARYING GAS STREAMS

• US 20110094263A1
• Filed: 10/22/2009
• Published: 04/28/2011
• Est. Priority Date: 10/22/2009
• Status: Active Grant

• Current Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Original Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Inventors: Wilding, Bruce M., Turner, Terry D.
• Granted Patent: US 8,899,074 B2
• 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 1/0045 by vaporising a liquid return stream
• CPC Class Codes: F25J 1/005 by expansion of a gaseous refrigerant stream with extraction of work
• CPC Class Codes: F25J 1/0072 Nitrogen
• CPC Class Codes: F25J 1/0201 using only internal refrigeration means, i.e. without external refrigeration
• CPC Class Codes: F25J 1/0204 as a single flow SCR cycle
• CPC Class Codes: F25J 1/0232 integration within a pressure letdown station of a high pressure pipeline system
• CPC Class Codes: F25J 2205/10 using combined expansion and separation, e.g. in a vortex tube, "Ranque tube" or a "cyclonic fluid separator", i.e. combination of an isentropic nozzle and a cyclonic separator; Centrifugal separation
• CPC Class Codes: F25J 2205/20 using solidification of components
• CPC Class Codes: F25J 2205/84 using filter
• CPC Class Codes: F25J 2210/02 Multiple feed streams, e.g. originating from different sources
• CPC Class Codes: F25J 2210/06 Splitting of the feed stream, e.g. for treating or cooling in different ways
• CPC Class Codes: F25J 2220/66 Separating acid gases, e.g. CO2, SO2, H2S or RSH
• CPC Class Codes: F25J 2230/60 the fluid being hydrocarbons or a mixture of hydrocarbons
• CPC Class Codes: F25J 2235/60 the fluid being (a mixture of) hydrocarbons
• CPC Class Codes: F25J 2245/90 the recycled stream being boil-off gas from storage
• CPC Class Codes: F25J 2290/60 Details about pipelines, i.e. network, for feed or product distribution

Abstract

A method of natural gas liquefaction may include cooling a gaseous NG process stream to form a liquid NG process stream. The method may further include directing the first tail gas stream out of a plant at a first pressure and directing a second tail gas stream out of the plant at a second pressure. An additional method of natural gas liquefaction may include separating CO₂ from a liquid NG process stream and processing the CO₂ to provide a CO₂ product stream. Another method of natural gas liquefaction may include combining a marginal gaseous NG process stream with a secondary substantially pure NG stream to provide an improved gaseous NG process stream. Additionally, a NG liquefaction plant may include a first tail gas outlet, and at least a second tail gas outlet, the at least a second tail gas outlet separate from the first tail gas outlet.

Claims

1. A method of natural gas liquefaction, comprising:

directing a gaseous natural gas process stream and a cooling stream into a plant;

cooling the gaseous natural gas process stream by transferring heat from the gaseous natural gas process stream to the cooling stream;

expanding the cooled gaseous natural gas process stream to form a liquid natural gas process stream and a first tail gas stream comprising a gaseous natural gas;

directing the first tail gas stream out of the plant at a first pressure;

separating a secondary liquid natural gas stream from the liquid natural gas process stream and vaporizing the secondary liquid natural gas stream with a heat exchanger to form a second tail gas stream comprising gaseous natural gas; and

directing the second tail gas stream out of the plant at a second pressure, the second pressure different than the first pressure of the first tail gas stream.

2. The method of claim 1, further comprising maintaining separation of the cooling stream from the gaseous natural gas process stream within the plant.

3. The method of claim 2, wherein directing a cooling stream into a plant further comprises directing a gaseous cooling stream into the plant having a gas composition different than a gas composition of the gaseous natural gas process stream directed into the plant.

4. The method of claim 2, wherein directing a cooling stream into a plant further comprises directing a gaseous cooling stream having a pressure different than a pressure of the gaseous natural gas process stream directed into the plant.

5. The method of claim 2, wherein directing a cooling stream into the plant comprises directing a cooling stream comprising gaseous natural gas into the plant.

6. The method of claim 1, wherein directing a gaseous natural gas process stream into a plant further comprises directing a gaseous natural gas process stream comprising carbon dioxide into the plant.

7. The method of claim 6, wherein expanding the cooled gaseous natural gas process stream to form a liquid natural gas process stream and a first tail gas stream comprising a gaseous natural gas further comprises expanding the cooled gaseous natural gas process stream to produce a solid carbon dioxide portion suspended in the liquid natural gas process stream.

8. The method of claim 7, further comprising:

separating the solid carbon dioxide portion from at least a portion of the liquid natural gas process stream to provide a substantially pure liquid natural gas;

sublimating the solid carbon dioxide; and

directing the sublimated carbon dioxide out of the plant.

9. The method of claim 8, wherein directing the sublimated carbon dioxide out of the plant comprises directing the sublimated carbon dioxide out of the plant in the first tail gas stream.

10. The method of claim 8, further comprising:

directing the solid carbon dioxide portion suspended in the liquid natural gas process stream into a transfer tank;

directing a transfer motive gas into the transfer tank to direct the solid carbon dioxide portion suspended in the liquid natural gas process stream into a hydrocyclone;

directing gases from the transfer tank out of the plant.

11. The method of claim 10, wherein directing gases from the transfer tank out of the plant comprises directing gases from the transfer tank out of the plant in the first tail gas stream.

12. The method of claim 10, wherein separating the solid carbon dioxide portion from at least a portion of the liquid natural gas process stream to provide a substantially pure liquid natural gas comprises directing the solid carbon dioxide portion through an underflow of the hydrocyclone and directing the substantially pure liquid natural gas through an overflow of the hydrocyclone.

13. The method of claim 10, wherein directing a transfer motive gas into the transfer tank comprises directing a transfer motive gas from a natural gas source having a lower pressure than a natural gas source for the gaseous natural gas process stream.

14. The method of claim 8, further comprising:

directing the liquid natural gas process stream to a storage tank to provide a substantially pure liquid natural gas to the storage tank; and

wherein separating a secondary liquid natural gas stream from the liquid natural gas process stream comprises separating a secondary liquid natural gas stream consisting of substantially pure liquid natural gas from the liquid natural gas process stream.

15. The method of claim 14, wherein directing the second tail gas stream out of the plant further comprises combusting the second tail gas stream.

16. The method of claim 15, wherein combusting the second tail gas stream comprises combusting the second tail gas stream in a flare.

17. The method of claim 15, wherein combusting the second tail gas stream comprises combusting the second tail gas stream in a combustion engine.

18. The method of claim 1, further comprising directing a separate third tail gas stream out of the plant.

19. The method of claim 18, wherein directing a separate third tail gas stream out of the plant comprises directing the cooling stream out of the plant in the separate third tail gas stream.

20. The method of claim 1, wherein directing a cooling stream into the plant comprises providing a closed-loop cooling stream.

21. The method of claim 1, further comprising directing each of the gaseous natural gas process stream, the cooling stream, the first tail gas stream and the second tail gas stream through a respective channel of a multi-pass heat exchanger.

22. The method of claim 1, further comprising:

compressing the cooling stream with a compressor;

expanding the cooling stream with an expander; and

powering the compressor, at least in part, with power generated by the expander.

23. The method of claim 22, further comprising extracting heat from the cooling stream with a heat exchanger after compressing the cooling stream with the compressor and prior to expanding the cooling stream with the expander.

24. A method of natural gas liquefaction, the method comprising:

directing a gaseous natural gas process stream comprising gaseous carbon dioxide (CO₂) into a plant;

cooling the gaseous natural gas process stream within a heat exchanger;

expanding the cooled gaseous natural gas process stream to form a liquid natural gas process stream comprising solid CO₂;

directing a substantially pure liquid natural gas into a storage tank;

separating the CO₂ from the liquid natural gas process stream and processing the CO₂ to provide a CO₂ product stream.

25. A method of natural gas liquefaction, the method comprising:

directing a marginal gaseous natural gas process stream comprising at least one impurity into a plant;

combining the marginal gaseous natural gas process stream with a secondary substantially pure natural gas stream to provide an improved gaseous natural gas process stream;

cooling the improved gaseous natural gas process stream within a heat exchanger;

expanding the cooled improved gaseous natural gas process stream to form a liquid natural gas process stream;

separating the at least one impurity from the liquid natural gas process stream to provide a substantially pure liquid natural gas process stream; and

providing the secondary substantially pure natural gas stream from the substantially pure liquid natural gas process stream.

26. A natural gas liquefaction plant, comprising:

a gaseous natural gas process stream inlet;

a multi-pass heat exchanger comprising a first channel configured to receive and cool a gaseous natural gas process stream;

an expander valve configured to cool at least a portion of the gaseous natural gas process stream to a liquid state;

a liquid natural gas outlet;

a first tail gas outlet; and

at least a second tail gas outlet, the at least a second tail gas outlet separate from the first tail gas outlet.

27. The natural gas liquefaction plant of claim 26, further comprising:

a second channel of the multi-pass heat exchanger configured to receive and heat a first tail gas; and

a third channel of the multi-pass heat exchanger configured to receive and heat a second tail gas.

28. The natural gas liquefaction plant of claim 26, further comprising:

the gaseous natural gas process stream inlet coupled to a first natural gas pipeline having a first pressure;

the first tail gas outlet coupled to a second natural gas pipeline having a second pressure; and

the at least a second tail gas outlet coupled to a third natural gas pipeline having a third pressure different than the second pressure of the second gas pipeline.

29. The natural gas liquefaction plant of claim 28, wherein the second pressure of the second natural gas pipeline and the third pressure of the third natural gas pipeline are each less than the first pressure of the first natural gas pipeline.