IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0459500
(2006-07-24)
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등록번호 |
US-7591149
(2009-10-20)
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발명자
/ 주소 |
- Ransbarger, Weldon L.
- Martinez, Bobby D.
- Praderio, Attilio J.
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출원인 / 주소 |
|
인용정보 |
피인용 횟수 :
5 인용 특허 :
6 |
초록
Cascade-type natural gas liquefaction methods and apparatus are provided, having enhanced thermodynamic efficiencies, through the use of added refrigeration levels in one or both of the ethylene and methane refrigeration systems thereof.
대표청구항
▼
What is claimed is: 1. A process for liquefying a predominantly methane stream, said process comprising:(a) generating at least four distinct refrigerant streams from a common first refrigerant stream; and (b) cooling at least a portion of said predominantly methane stream via indirect heat exchang
What is claimed is: 1. A process for liquefying a predominantly methane stream, said process comprising:(a) generating at least four distinct refrigerant streams from a common first refrigerant stream; and (b) cooling at least a portion of said predominantly methane stream via indirect heat exchange with at least a portion of each of said four distinct refrigerant streams, wherein said four distinct refrigerant streams consist essentially of methane, ethane and/or ethylene. 2. The process of claim 1, wherein said cooling of step (b) is carried out in at least one heat exchanging economizer having a separate pass for each of said four distinct refrigerant streams and wherein said heat exchanging economizer comprises a plate-fin heat exchanger. 3. The process of claim 1, wherein each of said distinct refrigerant streams has an initial temperature measured immediately prior to being used for said cooling of step (b) and wherein the initial temperature of each of said four distinct refrigerant streams is different. 4. The process of claim 1, wherein each of said four distinct refrigerant streams has an initial pressure measured immediately prior to being used for said cooling of step (b) and wherein the initial pressure of each of said four distinct refrigerant streams is different. 5. The process of claim 1, wherein at least a portion of said four distinct refrigerant streams are generated via expansion of at least a portion of said predominantly methane stream after said cooling of step (b). 6. The process of claim 1, wherein all of said four distinct refrigerant streams are expanded prior to being used for said cooling of step (b). 7. The process of claim 1, wherein at least two of said four distinct refrigerant streams are generated at least in part via expansion in serially connected expansion devices. 8. The process of claim 1, further comprising introducing at least a portion of each of said four distinct refrigerant streams into a compressor after using said four distinct refrigerant streams for said cooling of step (b). 9. The process of claim 1, wherein at least one of said distinct refrigerant streams comprises a liquid fraction and wherein said cooling of step (b) causes boiling of said liquid fraction. 10. The process of claim 1, wherein said first refrigerant stream is not a mixed refrigerant. 11. The process of claim 1, wherein said first refrigerant stream comprises predominately methane, ethane, and/or ethylene. 12. The process of claim 1, wherein said first refrigerant stream comprises predominately ethylene. 13. The process of claim 12, further comprising cooling said predominately methane stream via indirect heat exchange with a predominately methane refrigerant subsequent to said cooling of step (b) and cooling said predominately methane stream via indirect heat exchange with a predominately propane refrigerant prior to said cooling of step (b). 14. The process of claim 1, wherein said first refrigerant stream comprises predominately methane. 15. The process of claim 14, further comprising cooling said predominately methane stream via indirect heat exchange with a predominately propane, propylene, ethane, and/or ethylene refrigerant prior to said cooling of step (b). 16. The process of claim 1, where said first refrigerant stream comprises a portion of said predominantly methane stream. 17. The process of claim 1, wherein said generating of step (a) includes splitting at least a portion of said predominately methane stream into first and second fractions after said cooling of step (b), using at least a portion of said first fraction as a first one of said four distinct refrigerant streams, and using at least a portion of said second fraction to generate at least one other of said four distinct refrigerant streams. 18. The process of claim 17, wherein said generating of step (a) includes expanding at least a portion of said second fraction, phase separating the resulting expanded stream to thereby produce a third predominately vapor fraction and a fourth predominately liquid fraction, wherein at least a portion of said third predominately vapor fraction is used as a second one of said four distinct refrigerant streams. 19. The process of claim 18, wherein said generating of step (a) includes splitting at least a portion of said fourth predominately liquid fraction into fifth and sixth fractions, using at least a portion of said fifth fraction as a third one of said four distinct refrigerant streams. 20. The process of claim 19, wherein said generating of step (a) includes expanding at least a portion of said sixth fraction, phase separating the resulting expanded stream to thereby produce a seventh predominately vapor fraction and an eighth predominately liquid fraction, wherein at least a portion of said seventh predominately vapor fraction is used as a fourth one of said four distinct refrigerant streams. 21. The process of claim 20, wherein said generating step (a) includes expanding at least a portion of said eighth predominately liquid fraction, phase separating the resulting expanded stream to thereby produce a ninth predominately vapor fraction and a tenth predominately liquid fraction, wherein at least a portion of said ninth predominately vapor fraction is used as a fifth one of said distinct refrigerant streams. 22. The process of claim 21, further comprising recovering LNG from said tenth predominately liquid fraction. 23. The process of claim 1, further comprising vaporizing LNG produced in accordance with the process of claim 1. 24. A process of liquefying a natural gas stream, said process comprising:(a) cooling at least a portion of said natural gas stream via indirect heat exchange with a refrigerant in a first heat exchanging chiller;(b) generating at least three distinct refrigerant streams from said refrigerant employed in said first heat exchanging chiller; and(c) cooling at least a portion of said natural gas via indirect heat exchange with at least a portion of each of said distinct refrigerant streams in a heat exchanging economizer different than said first heat exchanging chiller. 25. The process of claim 24, wherein said first heat exchanging chiller comprises a core-in-kettle heat exchanger and said heat exchanging economizer comprises a plate-fin heat exchanger. 26. The process of claim 24, wherein each of said distinct refrigerant streams enters said heat exchanging economizer at a different temperature and pressure. 27. The process of claim 24, further comprising cooling at least a portion of said natural gas stream via indirect heat exchange with at least a portion of said refrigerant in a second heat exchanging chiller different than said first heat exchanging chiller. 28. The process of claim 27, wherein at least a portion of at least one of said distinct refrigerant streams is derived from the refrigerant employed in said second heat exchanging chiller. 29. The process of claim 24, wherein said refrigerant is not a mixed refrigerant. 30. The process of claim 24, wherein said refrigerant comprises predominately ethane and/or ethylene. 31. The process of claim 24, further comprising cooling at least a portion of said natural gas via indirect heat exchange with a predominately propane and/or propylene refrigerant prior to said cooling of step (a) and cooling at least a portion of said natural gas stream via indirect heat exchange with a predominately methane refrigerant subsequent to said cooling of step (a). 32. The process of claim 24, further comprising vaporizing LNG produced in accordance with the process of claim 24. 33. An apparatus for liquefying a predominantly methane stream, said apparatus comprising: a first mechanical refrigeration cycle employing a first refrigerant to cool at least a portion of said predominantly methane stream; and a second mechanical refrigeration cycle employing a second refrigerant to cool at least a portion of said predominantly methane stream downstream of said first mechanical refrigeration cycle, wherein at least one of said first and second mechanical refrigeration cycles includes a heat exchanging economizer, wherein said heat exchanging economizer defines at least one cooling pass for receiving a flow of said predominately methane stream and at least four warming passes for receiving a flow of at least four distinct refrigerant streams, wherein said heat exchanging economizer facilitates indirect heat exchange between said predominately methane stream in said cooling pass and each of said four distinct refrigerant streams in said warming passes. 34. The apparatus of claim 33, wherein said heat exchanging economizer comprises a plate-fin heat exchanger. 35. The apparatus of claim 33, wherein said at least one mechanical refrigerant cycle includes a multiple stream generating system for separating the refrigerant associated with said at least one mechanical refrigeration cycle into said at least four distinct refrigerant streams. 36. The apparatus of claim 33, wherein said multiple stream generating system includes a plurality of serially connected expansion devices. 37. The apparatus of claim 36, wherein said multiple stream generating system includes at least one vapor/liquid phase separating drum located downstream of at least one of said expansion devices. 38. The apparatus of claim 33, further comprising a compressor operable to receive and compress at least a portion of each of said four distinct refrigeration streams after passage though said heat exchanging economizer. 39. The apparatus of claim 33, wherein said second mechanical refrigeration cycle employs said heat exchanging economizer, wherein said first refrigerant comprises predominately propane, propylene, ethane, and/or ethylene. 40. The apparatus of claim 39, wherein said second refrigerant comprises predominately ethane and/or ethylene. 41. The apparatus of claim 39, wherein said second refrigerant comprises predominately methane.
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