US20090211297A1 - Helium production in lng plants - Google Patents
Helium production in lng plants Download PDFInfo
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- US20090211297A1 US20090211297A1 US11/817,359 US81735906A US2009211297A1 US 20090211297 A1 US20090211297 A1 US 20090211297A1 US 81735906 A US81735906 A US 81735906A US 2009211297 A1 US2009211297 A1 US 2009211297A1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
- F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
- F25J1/004—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas recovery
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
- F25J1/0022—Hydrocarbons, e.g. natural gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
- F25J3/0209—Natural gas or substitute natural gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
- F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
- F25J3/028—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of noble gases
- F25J3/029—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of noble gases of helium
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
- F25J3/0605—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the feed stream
- F25J3/061—Natural gas or substitute natural gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
- F25J3/063—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream
- F25J3/0685—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of noble gases
- F25J3/069—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of noble gases of helium
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2200/00—Processes or apparatus using separation by rectification
- F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2200/00—Processes or apparatus using separation by rectification
- F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2210/00—Processes characterised by the type or other details of the feed stream
- F25J2210/06—Splitting of the feed stream, e.g. for treating or cooling in different ways
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2215/00—Processes characterised by the type or other details of the product stream
- F25J2215/04—Recovery of liquid products
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2220/00—Processes or apparatus involving steps for the removal of impurities
- F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
- F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2280/00—Control of the process or apparatus
- F25J2280/02—Control in general, load changes, different modes ("runs"), measurements
Definitions
- the invention relates to a process for separating a helium-rich fraction from a liquefied natural gas stream.
- Helium is normally extracted in great quantities from natural gas or from natural gas fractions—such as accumulate, for example, in what are known as LNG baseload plants, from a gas mixture consisting essentially of methane, a high percentage of nitrogen and hydrocarbons.
- the liquefied natural gas present at high pressure whose temperature is almost determined because of the refrigerant(s) from the LNG baseload plant, is initially reduced to a median pressure between 3 and 10 bar, the helium-rich flash gas obtained thereby—which typically has a helium content of between 5% and 20%—is heated and taken to a helium extraction plant as a feedstock fraction.
- the helium-rich flash gas Prior to its being returned, the helium-rich flash gas is heated—for example, countercurrent to a purified, natural gas stream present under high pressure—which is drawn off before the actual liquefaction part of the liquefaction process and thus originates from what is known as the “warm area” of the liquefaction process—in order to be able to utilize the coldness of the helium-rich flash gas to cool and liquefy this additional natural gas flow.
- the volume of this additional natural gas flow must be selected such that there is no noticeable change in the liquefaction performance of the LNG baseload plant, which is the case in a broad range of volume flow.
- the object of the present invention is to specify a generic process for separating a helium-rich fraction from a liquefied natural gas stream which avoids the aforementioned disadvantages.
- the volume stream of the aforementioned natural gas stream to be cooled and liquefied is preferably adjusted such that no essential change results in the liquefaction performance of the LNG baseload plant.
- the process in accordance with the invention now makes it possible to cope with a wide variety in the helium and nitrogen contents in the natural gas stream to be liquefied and the liquefied natural gas stream.
- the helium-rich fraction and the natural gas stream to be cooled and liquefied which are brought together in the exchange of heat can now be heated or cooled, selectively temperature-controlled with respect to each other.
- the conditions for the expansion of the liquefied natural gas stream and the separation of the helium-rich fraction can be selectively regulated so that a maximum separation or yield of helium is possible for different compositions of liquefied natural gas streams through the expansion and separation of the helium-rich fraction.
- the volume flow of the helium-rich fraction taken to the heat exchange and/or the volume flow of the natural gas stream taken to the heat exchange to be cooled and liquefied is varied in such a way that the helium yield from the helium-rich fraction remains essentially constant and/or is maximized.
- the helium-depleted, liquefied natural gas stream is expanded and undergoes fuel-gas separation
- the fuel-gas fraction extracted in the fuel-gas separation is heated countercurrent to the natural gas stream to be cooled and liquefied
- At least one partial stream of the natural gas stream to be cooled and liquefied at least one partial stream of the helium-rich fraction to be heated and/or at least one partial stream of the fuel-gas fraction to be heated is taken past the heat exchange between the helium-rich fraction to be heated and the natural gas stream to be cooled and liquefied,
- the heat exchange between the helium-rich fraction to be heated and the natural gas stream to be cooled and liquefied takes place in at least one coil heat exchanger and/or at least one TEMA heat exchanger,
- the separation of the helium-rich fraction takes place in a separator or a wash column.
- FIG. 1 illustrates a first embodiment of the invention.
- FIG. 2 illustrates a second embodiment of the invention.
- a liquefied natural gas stream which was extracted in any kind of natural gas liquefaction process is brought in, expanded in valve a to a pressure between 3 and 10 bar and then taken to separator D via line 2 .
- a helium-rich gas fraction is withdrawn from the head of this separator D via line 3 .
- the helium-rich gas fraction is heated in heat exchanger E, which is preferably a coil heat exchanger or a TEMA heat exchanger, countercurrent to a natural gas stream to be cooled and liquefied, which will be discussed in greater detail in what follows, and then via line 4 taken for further use, such as a process in which a pure helium fraction is extracted.
- heat exchanger E which is preferably a coil heat exchanger or a TEMA heat exchanger
- a helium-depleted liquid fraction is drawn off via line 5 , expanded in valve b to a pressure between 1 and 5 bar and taken via line 6 to its further application—if necessary, following previous transfer by means of a pump and intermediate storage in a storage tank at atmospheric pressure.
- the natural gas stream mentioned which is to be cooled and liquefied is taken via line 9 to heat exchanger E.
- This gaseous natural gas stream is, for example, drawn off from the natural gas liquefaction process following the usually necessary separation of heavy hydrocarbons.
- the volume of this natural gas stream is preferably adjusted such that no noticeable change in the liquefaction performance of the LNG baseload plant results as a consequence of the helium separation D.
- the natural gas stream fed to the heat exchanger E via line 9 is now cooled and liquefied. It is then admixed via line 10 , in which an expansion valve c is provided, to the liquefied natural gas stream in line 2 before being taken to separator D.
- FIG. 1 two additional by-pass lines are shown in each of which a control valve d and e are located. Through these by-pass lines 7 and 11 the fractions taken in lines 3 and 9 can be passed completely or at least partially to heat exchanger E.
- the volume flow of the natural gas stream taken to heat exchanger E via line 9 by means of the expansion valve c and/or the by-pass line 11 can be varied.
- maximum helium yields or volumes can be adjusted or obtained even for different compositions of the liquefied natural gas stream in the helium-rich fraction 3 drawn off at the head of the separator D.
- the purpose of this procedure is to adjust the conditions in the separator D, meaning the entire enthalpy of the mixture, in such a way that even with different compositions of the natural gas streams 1 and 9 a maximum helium yield in the helium-rich flash gas 3 and 4 is achieved and at the same time the production of the LNG baseload process is not affected or affected only minimally. In this way an optimal starting fraction can be prepared for a downstream process for a pure helium extraction.
- heat exchanger E is preferably designed as a plate exchanger. In the event of greater temperature differences it is advantageous to implement heat exchanger E as a coil heat exchanger and/or TEMA heat exchanger.
- the process in accordance with the invention for separating a helium-rich fraction from a liquefied natural gas stream makes it possible to maximize the helium yields from the most highly varied liquefied natural gas streams.
- the required investment for controls can be kept within bounds so that implementing the process in accordance with the invention results in only insignificant additional costs.
Abstract
A process for separating a helium-rich fraction from a liquefied natural gas stream, is disclosed. In an embodiment, the process includes expansion of a liquefied natural gas stream and separation of the helium-rich fraction. The helium-rich fraction is heated countercurrent to a natural gas stream to be cooled and liquefied. The natural gas stream liquefied in a heat exchange countercurrent to the helium-rich fraction to be heated is fed prior to and/or in the separation of the helium-rich fraction. The total enthalpy of the mixture of the two aforementioned natural gas streams brought to the separation of the helium-rich fraction is variable.
Description
- This application claims the priority of International Application No. PCT/EP2006/001805, filed Feb. 28, 2006, and German Patent Document No. 10 2005 010 053.8, filed Mar. 4, 2005, the disclosures of which are expressly incorporated by reference herein.
- The invention relates to a process for separating a helium-rich fraction from a liquefied natural gas stream.
- Helium is normally extracted in great quantities from natural gas or from natural gas fractions—such as accumulate, for example, in what are known as LNG baseload plants, from a gas mixture consisting essentially of methane, a high percentage of nitrogen and hydrocarbons.
- Smaller amounts of helium can also be separated and thus extracted from the air in cryogenic air fractionating plants using what is known as low-temperature air fractionation. Helium occurs in known natural gas deposits in the amount of up to about 0.2% mole. For this reason, technical extraction makes sense only as part of the aforementioned LNG baseload plants since the inert helium is concentrated in them in the flash gas of the LNG storage tanks. When extracting helium at what is known as the “cold end” of LNG baseload plants, it is desirable to extract a constant volume of helium even with different compositions of natural gas although primarily the different concentrations of nitrogen of the natural gas result in different flash conditions for the helium-rich flash. Normally, the liquefied natural gas present at high pressure, whose temperature is almost determined because of the refrigerant(s) from the LNG baseload plant, is initially reduced to a median pressure between 3 and 10 bar, the helium-rich flash gas obtained thereby—which typically has a helium content of between 5% and 20%—is heated and taken to a helium extraction plant as a feedstock fraction.
- Prior to its being returned, the helium-rich flash gas is heated—for example, countercurrent to a purified, natural gas stream present under high pressure—which is drawn off before the actual liquefaction part of the liquefaction process and thus originates from what is known as the “warm area” of the liquefaction process—in order to be able to utilize the coldness of the helium-rich flash gas to cool and liquefy this additional natural gas flow. The volume of this additional natural gas flow must be selected such that there is no noticeable change in the liquefaction performance of the LNG baseload plant, which is the case in a broad range of volume flow.
- Using this process, however, different qualities of natural gas cannot be considered with respect to the content of helium and nitrogen which in turn result in great differences with respect to the helium and the nitrogen content in the flash gas separated from the liquefied natural gas. The object of the present invention is to specify a generic process for separating a helium-rich fraction from a liquefied natural gas stream which avoids the aforementioned disadvantages.
- To achieve this objective, a generic process is provided which comprises the following process steps:
- a) expanding the liquefied natural gas stream and separating a helium-rich fraction,
- b) heating the helium-rich fraction countercurrent to a natural gas stream to be cooled and liquefied, and
- c) feeding of the natural gas stream liquefied in the heat exchange countercurrent to the helium-rich fraction to be heated prior to and/or in the separation of the helium-rich fraction,
- d) where the total enthalpy of the mixture of the two aforementioned natural gas streams brought to the separation of the helium-rich fraction can be varied.
- The volume stream of the aforementioned natural gas stream to be cooled and liquefied is preferably adjusted such that no essential change results in the liquefaction performance of the LNG baseload plant.
- In principle, the total enthalpy of the mixture of the two aforementioned natural gas streams taken to the separation of the helium-rich fraction—this a two-phase stream—can happen by:
- varying the supercooling conditions of the liquefied natural gas at what is known as the “cold end” of the liquefaction process; however, this would require intervening in the operation of the LNG baseload plant, which is normally not desirable,
- heating the supercooled natural gas stream from the “cold end” of the LNG baseload plant countercurrent to one or more refrigerant streams; even this version would result in a normally undesirable intervention in the operation of the LNG baseload plant, or
- heating the supercooled natural gas stream from the “cold end” of the LNG baseload plant by admixing a hotter natural gas stream from the “hot end” of the LNG baseload plant; this alternative results in an increase in the throughput through the LNG baseload plant, for which reason this alternative is preferred.
- The process in accordance with the invention now makes it possible to cope with a wide variety in the helium and nitrogen contents in the natural gas stream to be liquefied and the liquefied natural gas stream. The helium-rich fraction and the natural gas stream to be cooled and liquefied which are brought together in the exchange of heat can now be heated or cooled, selectively temperature-controlled with respect to each other. Thus the conditions for the expansion of the liquefied natural gas stream and the separation of the helium-rich fraction can be selectively regulated so that a maximum separation or yield of helium is possible for different compositions of liquefied natural gas streams through the expansion and separation of the helium-rich fraction.
- Further developing the process in accordance with the invention, it is provided that—consistent with the composition of the natural gas streams—the volume flow of the helium-rich fraction taken to the heat exchange and/or the volume flow of the natural gas stream taken to the heat exchange to be cooled and liquefied is varied in such a way that the helium yield from the helium-rich fraction remains essentially constant and/or is maximized.
- Additional advantageous embodiments of the process in accordance with the invention are characterized in that:
- the helium-depleted, liquefied natural gas stream is expanded and undergoes fuel-gas separation,
- the fuel-gas fraction extracted in the fuel-gas separation is heated countercurrent to the natural gas stream to be cooled and liquefied,
- at least one partial stream of the natural gas stream to be cooled and liquefied, at least one partial stream of the helium-rich fraction to be heated and/or at least one partial stream of the fuel-gas fraction to be heated is taken past the heat exchange between the helium-rich fraction to be heated and the natural gas stream to be cooled and liquefied,
- the heat exchange between the helium-rich fraction to be heated and the natural gas stream to be cooled and liquefied takes place in at least one coil heat exchanger and/or at least one TEMA heat exchanger,
- the separation of the helium-rich fraction takes place in a separator or a wash column.
-
FIG. 1 illustrates a first embodiment of the invention. -
FIG. 2 illustrates a second embodiment of the invention. - Via
line 1—as shown in FIG. 1—a liquefied natural gas stream which was extracted in any kind of natural gas liquefaction process is brought in, expanded in valve a to a pressure between 3 and 10 bar and then taken to separator D vialine 2. A helium-rich gas fraction is withdrawn from the head of this separator D vialine 3. - The helium-rich gas fraction is heated in heat exchanger E, which is preferably a coil heat exchanger or a TEMA heat exchanger, countercurrent to a natural gas stream to be cooled and liquefied, which will be discussed in greater detail in what follows, and then via
line 4 taken for further use, such as a process in which a pure helium fraction is extracted. - From the sump of the separator D, a helium-depleted liquid fraction is drawn off via
line 5, expanded in valve b to a pressure between 1 and 5 bar and taken vialine 6 to its further application—if necessary, following previous transfer by means of a pump and intermediate storage in a storage tank at atmospheric pressure. - The natural gas stream mentioned which is to be cooled and liquefied is taken via
line 9 to heat exchanger E. This gaseous natural gas stream is, for example, drawn off from the natural gas liquefaction process following the usually necessary separation of heavy hydrocarbons. The volume of this natural gas stream is preferably adjusted such that no noticeable change in the liquefaction performance of the LNG baseload plant results as a consequence of the helium separation D. - By exploiting the cold from the helium-rich fraction supplied by
line 3 to the heat exchanger E, the natural gas stream fed to the heat exchanger E vialine 9 is now cooled and liquefied. It is then admixed vialine 10, in which an expansion valve c is provided, to the liquefied natural gas stream inline 2 before being taken to separator D. - Depending on the mixture temperature and pressure, different helium concentrations and volumes result in the helium-
rich gas fraction 3 drawn off at the head of the separator D. - In
FIG. 1 , two additional by-pass lines are shown in each of which a control valve d and e are located. Through these by-pass lines lines - In accordance with the invention, the volume flow of the natural gas stream taken to heat exchanger E via
line 9 by means of the expansion valve c and/or the by-pass line 11 can be varied. The same applies to the helium-rich fraction brought to heat exchanger E vialine 3 since its volume flow can be regulated by heat exchanger E by means of the by-pass line 7. - By means of the aforementioned control mechanisms, maximum helium yields or volumes can be adjusted or obtained even for different compositions of the liquefied natural gas stream in the helium-
rich fraction 3 drawn off at the head of the separator D. - In accordance with the volume, the composition, the degree of supercooling and the pre-pressure and thus the total enthalpy of the liquefied natural gas stream brought in over
line sections lines rich fraction 3. - The purpose of this procedure is to adjust the conditions in the separator D, meaning the entire enthalpy of the mixture, in such a way that even with different compositions of the
natural gas streams 1 and 9 a maximum helium yield in the helium-rich flash gas - If comparatively low temperature differences between 5 and 30 K occur in heat exchanger E, the heat exchanger is preferably designed as a plate exchanger. In the event of greater temperature differences it is advantageous to implement heat exchanger E as a coil heat exchanger and/or TEMA heat exchanger.
- In particular when the volumes of the streams brought in over
line sections line sections pass line 11 at the outlet of heat exchanger E. - Using the embodiment shown in
FIG. 1 of the process in accordance with the invention, however, a maximum of 97% of the helium contained in the natural gas stream can be extracted. - If—as is shown in FIG. 2—the separator D is replaced by a wash column (K), a helium yield of up to 99.9% can be realized.
- To do this, it is necessary to take the natural gas stream liquefied in heat exchanger E′—which is cooled countercurrent to the helium-
rich gas fraction 3′ which is to be heated—vialine 10′ to the wash column (K) as a strip stream while the liquefied natural gas stream expanded in valve a′, is given up vialine 2′ to the wash column (K) as reflux. - This increase in the helium yield certainly requires an increase in the costs for equipment and technology but appears acceptable in view of the value of helium.
- The process in accordance with the invention for separating a helium-rich fraction from a liquefied natural gas stream makes it possible to maximize the helium yields from the most highly varied liquefied natural gas streams. The required investment for controls can be kept within bounds so that implementing the process in accordance with the invention results in only insignificant additional costs.
Claims (11)
1-6. (canceled)
7. A process for separating a helium-rich fraction from a liquefied natural gas stream, comprising the steps of:
a) expansion of a liquefied natural gas stream and separation of the helium-rich fraction;
b) heating of the helium-rich fraction countercurrent to a natural gas stream to be cooled and liquefied; and
c) feeding of the natural gas stream liquefied in a heat exchange countercurrent to the helium-rich fraction to be heated prior to and/or in the separation of the helium-rich fraction;
d) wherein the total enthalpy of the mixture of the two aforementioned natural gas streams brought to the separation of the helium-rich fraction is variable.
8. The process according to claim 7 , wherein a temperature of the natural gas stream liquefied in the heat exchange countercurrent to the helium-rich fraction to be heated is variable.
9. The process according to claim 7 , wherein a volume flow of the helium-rich fraction taken to the heat exchange and/or a volume flow of the natural gas stream taken to the heat exchange to be cooled and liquefied, is varied such that a helium yield from the helium-rich fraction remains essentially constant and/or is maximized.
10. The process according to claim 7 , wherein at least one partial stream of the natural gas stream to be cooled and liquefied and/or at least one partial stream of the helium-rich fraction to be heated is taken past the heat exchange between the helium-fraction to be heated and the natural gas stream to be cooled and liquefied.
11. The process according to claim 7 , wherein the heat exchange between the helium-rich fraction to be heated and the natural gas stream to be cooled and liquefied takes place in at least one coil heat exchanger and/or at least one TEMA heat exchanger.
12. The process according to claim 7 , wherein the separation of the helium-rich fraction is implemented in a separator or a wash column.
13. A process for separating a helium-rich fraction from a liquefied natural gas stream, comprising the steps of:
expanding a liquefied natural gas stream;
cooling and liquefying a natural gas stream in a heat exchanger;
providing the liquefied natural gas stream and the cooled and liquefied natural gas stream as a mixture to a separator; and
separating a helium-rich fraction from the mixture in the separator;
wherein the helium-rich fraction is provided from the separator to the heat exchanger for cooling and liquefying the natural gas stream and wherein a total enthalpy of the mixture is variable.
14. The process according to claim 13 , further comprising the steps of controlling a volume of the natural gas stream cooled and liquefied in the heat exchanger and controlling a volume of the helium-rich fraction provided from the separator to the heat exchanger.
15. The process according to claim 13 , further comprising the step of controlling a yield of helium in the helium-rich fraction by adjusting a temperature of the cooled and liquefied natural gas stream.
16. The process according to claim 14 , wherein the step of controlling the volume of the natural gas stream cooled and liquefied in the heat exchanger and the step of controlling the volume of the helium-rich fraction provided from the separator to the heat exchanger include the step of bypassing a portion of the natural gas stream and the helium-rich fraction around the heat exchanger.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102005010053A DE102005010053A1 (en) | 2005-03-04 | 2005-03-04 | Helium recovery in LNG plants |
DE102005010053.8 | 2005-03-04 | ||
PCT/EP2006/001805 WO2006094676A1 (en) | 2005-03-04 | 2006-02-28 | Helium production in lng plants |
Publications (1)
Publication Number | Publication Date |
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US20090211297A1 true US20090211297A1 (en) | 2009-08-27 |
Family
ID=36423588
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/817,359 Abandoned US20090211297A1 (en) | 2005-03-04 | 2006-02-28 | Helium production in lng plants |
Country Status (5)
Country | Link |
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US (1) | US20090211297A1 (en) |
AU (1) | AU2006222326B2 (en) |
DE (1) | DE102005010053A1 (en) |
RU (1) | RU2007136599A (en) |
WO (1) | WO2006094676A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2011073476A1 (en) * | 2009-10-26 | 2011-06-23 | Consejo Superior De Investigaciones Científicas (Csic) | Helium-recovery plant |
US20150013349A1 (en) * | 2012-02-10 | 2015-01-15 | Csic Pride (Nanjing) Cryogenic Technology Co., Ltd. | Low-temperature device for separating and purifying gas based on small-sized low-temperature refrigerating machine |
CN107228526A (en) * | 2017-07-03 | 2017-10-03 | 成都深冷液化设备股份有限公司 | A kind of LNG flashed vapours carry helium, denitrogenation and reliquefaction installation |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102012000147A1 (en) * | 2012-01-05 | 2013-07-11 | Linde Aktiengesellschaft | Method for obtaining a helium pure fraction |
FR3088416B1 (en) * | 2018-11-08 | 2020-12-11 | Air Liquide | METHOD AND APPARATUS FOR LIQUEFACTION OF A GAS CURRENT CONTAINING CARBON DIOXIDE |
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Also Published As
Publication number | Publication date |
---|---|
RU2007136599A (en) | 2009-04-10 |
DE102005010053A1 (en) | 2006-09-07 |
AU2006222326B2 (en) | 2011-03-24 |
AU2006222326A1 (en) | 2006-09-14 |
WO2006094676A1 (en) | 2006-09-14 |
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