Liquefied Natural Gas and Hydrocarbon Gas Processing

a technology of hydrocarbon gas and natural gas, applied in the direction of refrigeration and liquidation, lighting and heating apparatus, solidification, etc., can solve the problems of high recovery, low utility cost, and process simplicity, so as to achieve low capital investment and reduce utility costs

Inactive Publication Date: 2009-11-19
ORTLOFF ENGINEERS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007]Heretofore, assignee's U.S. Pat. No. 7,216,507 has been used to recover C2 components and heavier hydrocarbon components in plants processing LNG, while assignee's U.S. Pat. No. 5,568,737 has been used to recover C2 components and heavier hydrocarbon components in plants processing natural gas. Surprisingly, applicants have found that by integrating certain features of the assignee's U.S. Pat. No. 7,216,507 invention with certain features of the assignee's U.S. Pat. No. 5,568,737, extremely high C2 component recovery levels can be accomplished using less energy than that required by individual plants to process the LNG and natural gas separately.

Problems solved by technology

Although there are many processes which may be used to separate ethane and / or propane and heavier hydrocarbons from LNG, these processes often must compromise between high recovery, low utility costs, and process simplicity (and hence low capital investment).
However, lower utility costs may be possible if the lean LNG is instead produced as a liquid stream that can be pumped (rather than compressed) to the delivery pressure of the gas distribution network, with the lean LNG subsequently vaporized using a low level source of external heat or other means.

Method used

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  • Liquefied Natural Gas and Hydrocarbon Gas Processing

Examples

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example 1

[0040]FIG. 3 illustrates a flow diagram of a process in accordance with the present invention. The LNG stream and inlet gas stream compositions and conditions considered in the process presented in FIG. 3 are the same as those in the FIG. 1 and FIG. 2 processes. Accordingly, the FIG. 3 process can be compared with the FIG. 1 and FIG. 2 processes to illustrate the advantages of the present invention.

[0041]In the simulation of the FIG. 3 process, the LNG to be processed (stream 71) from LNG tank 50 enters pump 51 at −251° F. [−157° C.]. Pump 51 elevates the pressure of the LNG sufficiently so that it can flow through heat exchangers and thence to separator 54. Stream 71a exits the pump at −242° F. [−152° C.] and 1364 psia [9,401 kPa(a)] and is split into two portions, streams 72 and 73. The first portion, stream 72, becomes stream 75 and is expanded to the operating pressure (approximately 415 psia [2,859 kPa(a)]) of fractionation column 62 by expansion valve 58. The expanded stream 7...

example 2

[0058]An alternative method of processing natural gas is shown in another embodiment of the present invention as illustrated in FIG. 4. The LNG stream and inlet gas stream compositions and conditions considered in the process presented in FIG. 4 are the same as those in FIGS. 1 through 3. Accordingly, the FIG. 4 process can be compared with the FIGS. 1 and 2 processes to illustrate the advantages of the present invention, and can likewise be compared to the embodiment displayed in FIG. 3.

[0059]In the simulation of the FIG. 4 process, the LNG to be processed (stream 71) from LNG tank 50 enters pump 51 at −251° F. [−157° C.]. Pump 51 elevates the pressure of the LNG sufficiently so that it can flow through heat exchangers and thence to separator 54. Stream 71a exits the pump at −242° F. [−152° C.] and 1364 psia [9,401 kPa(a)] and is split into two portions, streams 72 and 73. The first portion, stream 72, becomes stream 75 and is expanded to the operating pressure (approximately 415 p...

example 3

[0070]Another alternative method of processing natural gas is shown in the embodiment of the present invention as illustrated in FIG. 5. The LNG stream and inlet gas stream compositions and conditions considered in the process presented in FIG. 5 are the same as those in FIGS. 1 through 4. Accordingly, the FIG. 5 process can be compared with the FIGS. 1 and 2 processes to illustrate the advantages of the present invention, and can likewise be compared to the embodiments displayed in FIGS. 3 and 4.

[0071]In the simulation of the FIG. 5 process, the LNG to be processed (stream 71) from LNG tank 50 enters pump 51 at −251° F. [−157° C.]. Pump 51 elevates the pressure of the LNG sufficiently so that it can flow through heat exchangers and thence to separator 54. Stream 71a exits the pump at −242° F. [−152° C.] and 1364 psia [9,401 kPa(a)] and is split into two portions, streams 72 and 73. The first portion, stream 72, becomes stream 75 and is expanded to the operating pressure (approximat...

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Abstract

A process for the recovery of ethane, ethylene, propane, propylene, and heavier hydrocarbons from a liquefied natural gas (LNG) stream and a hydrocarbon gas stream is disclosed. The LNG feed stream is divided into two portions. The first portion is supplied to a fractionation column at a first upper mid-column feed point. The second portion is directed in heat exchange relation with a first portion of a warmer distillation stream rising from the fractionation stages of the column, whereby the LNG feed stream is partially heated and the distillation stream is totally condensed. The condensed distillation stream is divided into a “lean” LNG stream and a reflux stream, whereupon the reflux stream is supplied to the column at a top column feed position. The second portion of the LNG feed stream is heated further to partially or totally vaporize it and thereafter supplied to the column at a first lower mid-column feed position. The gas stream is divided into two portions. The second portion is expanded to the operating pressure of the column, then both portions are directed in heat exchange relation with the lean LNG stream and the second portion of the warmer distillation stream, whereby both portions of the gas stream are cooled, the lean LNG stream is vaporized, and the second portion of the distillation stream is heated. The first portion of the gas stream, which has been cooled to substantial condensation, is supplied to the column at a second upper mid-column feed point, and the second portion is supplied to the column at a second lower mid-column feed point. The quantities and temperatures of the feeds to the column are effective to maintain the column overhead temperature at a temperature whereby the major portion of the desired components is recovered in the bottom liquid product from the column.

Description

[0001]This invention relates to a process for the separation of ethane and heavier hydrocarbons or propane and heavier hydrocarbons from liquefied natural gas (hereinafter referred to as LNG) combined with the separation of a gas containing hydrocarbons to provide a volatile methane-rich gas stream and a less volatile natural gas liquids (NGL) or liquefied petroleum gas (LPG) stream. The applicants claim the benefits under Title 35, United States Code, Section 119(e) of prior U.S. Provisional Application No. 61 / 053,814 which was filed on May 16, 2008.BACKGROUND OF THE INVENTION[0002]As an alternative to transportation in pipelines, natural gas at remote locations is sometimes liquefied and transported in special LNG tankers to appropriate LNG receiving and storage terminals. The LNG can then be re-vaporized and used as a gaseous fuel in the same fashion as natural gas. Although LNG usually has a major proportion of methane, i.e., methane comprises at least 50 mole percent of the LNG...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F25J3/00
CPCF25J3/0209F25J3/0214F25J3/0233F25J3/0238F25J2200/02F25J2200/38F25J2200/72F25J2200/76F25J2200/78F25J2205/04F25J2210/02F25J2210/06F25J2210/62F25J2230/08F25J2230/60F25J2235/60F25J2240/02F25J2270/904F25J2290/50
Inventor MARTINEZ, TONY L.WILKINSON, JOHN D.HUDSON, HANK M.CUELLAR, KYLE T.
Owner ORTLOFF ENGINEERS
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