IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0381904
(2006-05-05)
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등록번호 |
US-7594414
(2009-10-12)
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발명자
/ 주소 |
- Wilding, Bruce M.
- McKellar, Michael G.
- Turner, Terry D.
- Carney, Francis H.
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출원인 / 주소 |
- Battelle Energy Alliance, LLC
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대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
12 인용 특허 :
90 |
초록
▼
An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of 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
An apparatus and method for producing liquefied natural gas. A liquefaction plant may be coupled to a source of 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 passes through an expander creating work output. A compressor may be driven by the work output and compresses the process stream. The compressed process stream is cooled, such as by the expanded cooling stream. The cooled, compressed process stream is divided into first and second portions with the first portion being expanded to liquefy the natural gas. A gas-liquid separator separates the vapor from the liquid natural gas. The second portion of the cooled, compressed process stream is also expanded and used to cool the compressed process stream.
대표청구항
▼
What is claimed is: 1. A liquefaction plant comprising: a first flow path defined and configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger; a second flow path defined and configur
What is claimed is: 1. A liquefaction plant comprising: a first flow path defined and configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger; a second flow path defined and configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger; and at least two paths including a cooling path having a first expansion valve therein and a liquid production path having a second expansion valve therein formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, wherein the cooling path selectively is defined and configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and wherein the liquid production path is defined and configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator. 2. The liquefaction plant of claim 1, further comprising at least one hydrocyclone located and configured to receive a solid-liquid slurry from the gas-liquid separator, wherein an underflow of the at least one hydrocyclone is in fluid communication with the second side of the second heat exchanger. 3. The liquefaction plant of claim 2, further comprising at least one filter in fluid communication with an overflow of the at least one hydrocyclone. 4. The liquefaction plant of claim 1, further comprising valving and piping located and configured to selectively discharge the second stream of natural gas at least two different locations within the second side of the second heat exchanger. 5. The liquefaction plant of claim 1, wherein the first heat exchanger is configured as a countercurrent flow heat exchanger wherein the first side of the second heat exchanger includes a first heat exchange flow path and the second side of the second heat exchanger includes a second heat exchange flow path running countercurrent to the first heat exchange flow path. 6. The liquefaction plant of claim 5, further comprising valving and piping located and configured to selectively direct at least a portion of the first stream of natural gas out of the first heat exchange flow path and to the first side of the second heat exchanger so as to short circuit at least a portion of the first heat exchange flow path. 7. The liquefaction plant of claim 1, wherein the second heat exchanger includes at least one coil disposed within a shell, and wherein the first side of the second heat exchanger includes a flow path through the at least one coil and wherein the second side of the second heat exchanger includes a flow path between the at least one coil and the shell. 8. The liquefaction plant of claim 1, wherein the expander and the compressor are mechanically coupled to each other and wherein work derived from the expander drives the compressor. 9. The liquefaction plant of claim 8, further comprising a third flow path including a third stream of natural gas directed to at least one gas bearing associated with the mechanically coupled compressor and expander. 10. The liquefaction plant of claim 1, further comprising a third heat exchanger disposed between the compressor and the first side of the first heat exchanger such that first stream of natural gas sequentially flows from the compressor through the third heat exchanger and through the first side of the first heat exchanger. 11. A liquefaction plant comprising: a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger; a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger; at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and wherein the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator; and a surge protection loop comprising valving and piping located and configured to selectively direct at least a portion of the first stream of natural gas from a location between the compressor and the first side of the first heat exchanger back to an inlet of the compressor. 12. A liquefaction plant comprising: a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger; a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger; at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and wherein the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator; and valving and piping configured to direct a portion of the first stream of natural gas to the gas-liquid separator such that the portion of the first stream of natural gas bubbles through any liquid contained therein. 13. The liquefaction plant of claim 12, further comprising a converging nozzle disposed in the gas-liquid separator and coupled with an outlet thereof. 14. A liquefaction plant comprising: a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger; a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger; at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator; and a source of methanol located and configured to introduce a volume of methanol into the first flow path at a location prior to an intended flow of natural gas through the compressor. 15. The liquefaction plant of claim 14, further comprising at least one separating device disposed in the first flow path located and configured to substantially remove the volume of methanol and any water associated therewith. 16. The liquefaction plant of claim 15, wherein the at least one separating device includes at least one coalescing filter. 17. A liquefaction plant comprising: a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger; a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger; at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator; a liquid storage tank and another flow path defined between the gas-liquid separator and the liquid storage tank, and a first vent line coupled with the gas-liquid separator and a valve disposed within the first vent line providing selective communication between the gas-liquid separator and the liquid storage tank such that, when the valve is in an open position, a pressure in the gas-liquid separator is substantially the same as a pressure in the liquid storage tank. 18. The liquefaction plant of claim 17, further comprising a second vent line extending from the gas-liquid separator and the second heat exchanger, and a back-pressure regulator coupled with the second vent line, wherein when the valve in the first vent line is closed, the back pressure regulator is configured to develop an increased pressure within the gas-liquid separator. 19. A method of producing liquid natural gas, the method comprising: providing a source of unpurified natural gas and flowing a portion of the unpurified natural gas from the source; dividing the portion of unpurified natural gas into at least a process stream and a cooling stream; flowing the process stream sequentially through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger; flowing the cooling stream sequentially through an expander, through a second side of the second heat exchanger and into the source; sensing a temperature of the process stream after it exits the first side of the second heat exchanger; flowing substantially all of the process stream from the first side of the second heat exchanger to the second side of the first heat exchanger if the sensed temperature is warmer than a specified temperature; and flowing a first portion of the process stream from the first side of the second heat exchanger to the second side of the second heat exchanger and flowing a second portion of the process stream from the first side of the second heat exchanger to a gas-liquid separator if the sensed temperature is colder than the specified temperature. 20. The method according to claim 19, wherein the specified temperature is between approximately-175° F. and-205° F. 21. The method according to claim 19, wherein flowing substantially all of the process stream from the first side of the second heat exchanger to the second side of the first heat exchanger further includes flowing at least a portion of the process stream through an expansion valve. 22. The method according to claim 19, wherein flowing a second portion of the process stream from the first side of the second heat exchanger to a gas-liquid separator further includes flowing the second portion of the process stream through an expansion valve. 23. The method according to claim 19, further comprising producing a slurry of liquid natural gas and solid carbon dioxide from the second portion of the process stream within the liquid-gas separator. 24. The method according to claim 23, further comprising agitating the slurry to keep the solid carbon dioxide substantially suspended within the liquid natural gas. 25. The method according to claim 24, wherein agitating the slurry further includes bubbling a gas through the slurry. 26. The method according to claim 25, wherein bubbling a gas through the slurry includes diverting another portion of the process stream to the liquid-gas separator. 27. The method according to claim 24, wherein agitating the slurry further includes effecting nucleate boiling within the liquid natural gas. 28. The method according to claim 24, further comprising flowing the slurry through a converging nozzle as it exits the liquid-gas separator. 29. The method according to claim 19, further comprising selectively flowing a slurry of liquid natural gas and solid carbon dioxide from the liquid-gas separator to a hydrocyclone. 30. The method according to claim 29, further comprising flowing a slush that is rich in solid carbon dioxide through an underflow of the hydrocyclone to the second side of the second heat exchanger. 31. The method according to claim 30, further comprising flowing liquid natural gas through an overflow of the hydrocyclone to a storage tank. 32. The method according to claim 30, further comprising maintaining a pressure within the gas-liquid separator and a pressure within the storage tank at a substantially common pressure while slurry is not flowing from the gas-liquid separator to the hydrocyclone. 33. The method according to claim 32, further comprising increasing the pressure within the gas-liquid separator to a pressure greater than the pressure in the storage tank when the slurry is flowing to the hydrocyclone. 34. The method according to claim 30, further comprising flowing the liquid natural gas through at least one filter prior to flowing the liquid natural gas to the storage tank. 35. The method according to claim 30, further comprising managing a composition of the slush by controlling a pressure differential between the underflow and the overflow of the hydrocyclone. 36. The method according to claim 29, further comprising subliming the solid carbon dioxide in the second side of the second heat exchanger. 37. The method according to claim 23, further comprising subcooling the solid carbon dioxide. 38. The method according to claim 19, further comprising flowing any vapor within the liquid-gas separator to the second side of the second heat exchanger. 39. The method according to claim 19, further comprising monitoring a flow rate of the process stream through the compressor and, if the monitored flow rate is less than a specified flow rate, diverting at least a portion of the process stream from a location between the compressor and the first side of the first heat exchanger to an inlet of the compressor. 40. The method according to claim 39, wherein the diverting further includes opening a valve disposed in piping that provides a flow path from the location between the compressor and the first side of the first heat exchanger and the inlet of the compressor. 41. The method according to claim 40, further comprising closing the valve when the monitored flow rate exceeds the specified flow rate. 42. The method according to claim 19, wherein flowing a first portion of the process stream from the first side of the second heat exchanger to the second side of the second heat exchanger and flowing a second portion of the process stream from the first side of the second heat exchanger to a gas-liquid separator if the sensed temperature is colder than the specified temperature includes controlling a flow rate of the first portion of the process stream and a flow rate of the second portion of the process stream based, at least in part, on the sensed temperature. 43. The method according to claim 42, wherein controlling a flow rate of the first portion of the process stream and a flow rate of the second portion of the process stream includes actuating at least one valve. 44. The method according to claim 43, wherein actuating at least one valve includes actuating at least a first valve associated with the flow of the first portion of the process stream and actuating at least a second valve associated with the flow of the second portion of the process stream. 45. The method according to claim 43, wherein controlling a flow rate of the first portion of the process stream and a flow rate of a second portion of the process stream and actuating at least one valve includes controlling the opening and closing of the at least one valve with a proportional, integral, derivative (PID) control loop. 46. The method according to claim 45, wherein controlling the opening and closing of the at least one valve with a proportional, integral, derivative (PID) control loop includes mapping a gain of a proportional control of the PID control loop against a temperature range. 47. The method according to claim 46, further comprising defining the temperature range based on a phase change of the unpurified natural gas between a liquid phase and a gas phase. 48. The method according to claim 47, further comprising defining the temperature range to be from approximately-205° F. to approximately-140° F.
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