EP0687353B1 - Verfahren und vorrichtung zur verflüssigung von erdgas - Google Patents

Verfahren und vorrichtung zur verflüssigung von erdgas Download PDF

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Publication number
EP0687353B1
EP0687353B1 EP95905171A EP95905171A EP0687353B1 EP 0687353 B1 EP0687353 B1 EP 0687353B1 EP 95905171 A EP95905171 A EP 95905171A EP 95905171 A EP95905171 A EP 95905171A EP 0687353 B1 EP0687353 B1 EP 0687353B1
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EP
European Patent Office
Prior art keywords
natural gas
fraction
liquefying
liquid
gas
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Expired - Lifetime
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EP95905171A
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English (en)
French (fr)
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EP0687353A1 (de
Inventor
Isabelle Prevost
Alexandre Rojey
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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Priority claimed from FR9315924A external-priority patent/FR2714720B3/fr
Application filed by IFP Energies Nouvelles IFPEN filed Critical IFP Energies Nouvelles IFPEN
Publication of EP0687353A1 publication Critical patent/EP0687353A1/de
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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
    • F25J3/0257—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 nitrogen
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    • 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
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    • 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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    • 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"
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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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/30—Dynamic liquid or hydraulic expansion with extraction of work, e.g. single phase or two-phase turbine
    • 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
    • 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/04—Internal refrigeration with work-producing gas expansion loop
    • F25J2270/06—Internal refrigeration with work-producing gas expansion loop with multiple gas expansion loops
    • 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/12—External refrigeration with liquid vaporising loop
    • 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/88—Quasi-closed internal refrigeration or heat pump cycle, if not otherwise provided

Definitions

  • Natural gas liquefaction is an industrial operation important for transporting natural gas over long periods distances by LNG carrier, or to store them in liquid form.
  • an external refrigeration cycle using as refrigerant a mixture of fluids is used.
  • Such vaporizing mixture may refrigerate and liquefy gas under pressure. After vaporization, the mixture is compressed, condensed into exchanging heat with an ambient medium such as water or the air.
  • a first refrigeration step of refrigerate and liquefy natural gas directly by relaxing through a turbine from a "dense" phase denotes a phase obtainable from a gas phase initial by an isobaric evolution without phase transition and leading by isentropic expansion to a liquid phase without phase transition. At at least part of the liquefaction process takes place without transition from phase, i.e. the transition from the gas phase to the liquid phase takes place continuously, without transformation during which it two different phases would coexist. Natural gas is brought in "dense phase” before expansion, operating at a pressure at least higher than the critical methane pressure, and lowering the "natural gas" temperature.
  • the present invention relates to a process for liquefying a gas natural. It is characterized in that it comprises a step according to which at least partially liquefies said gas by expansion with supply of mechanical energy, this relaxation taking it from a state or phase dense to a liquid state or phase.
  • the first relaxed majority fraction is preferably greater than two thirds of the dense phase natural gas from the first stage.
  • a turbine is used as a device to relax the gas and move it from the dense phase state to the phase state liquid.
  • natural gas can be cooled by exchange thermal using a gaseous fraction from said natural gas, said gas fraction being expanded in a turbine, said fraction expanded gas being at least partly recompressed in a stage of compression and recycled.
  • At least one recycled gas fraction is compressed using at least two stages, the gas being cooled at the outlet of each of the stages of compression by an ambient medium of refrigeration available.
  • natural gas can also be cooled by vaporization of a mixture of refrigerants, the mixture thus obtained present in vapor or gas phase. It is then compressed, condensed by a heat exchange with the ambient medium of refrigeration available, relaxed and recycled.
  • the refrigerant mixture can be expanded and vaporized to at least two pressure levels.
  • Step a) is carried out at a pressure higher than the pressure critical of methane and preferably higher than the critical pressure of natural gas, to be liquefied.
  • step a) is carried out at a pressure value higher than the gas cricondenbar natural to liquefy.
  • Step a) is carried out at a pressure that is preferably understood to be between 7 and 20 MPa.
  • the temperature that natural gas has at the end of step a) is preferably between 165 and 230 K.
  • Natural gas during step a) is expanded to a pressure such that after expansion, a liquid fraction concentrated in hydrocarbons heavier than methane is produced, said fraction liquid then being separated.
  • Step b) is, for example, carried out by expansion in a turbine whose elements are thermally insulated from gas, at least one of the elements being made of a material little conductor of heat.
  • Step b) is, for example, carried out by expansion in a turbine having a rotor made of composite material, not very conductive of heat.
  • the heat exchanges during steps a) and d) can be carried out by passing the gas through exchangers operating against the current.
  • the heat exchange in step d) can be carried out by passing the gas in an exchanger with a temperature difference on the side cooler of the exchanger less than 5 K and a temperature difference on the side the hottest heat exchanger less than 10 K.
  • the relaxation can be achieved during step b) by means of minus two successive turbines, the liquid-vapor mixture coming from the first partial expansion being separated, into a gaseous fraction and a liquid fraction, said gaseous fraction being sent to carry out the step d) and said resulting liquid fraction being expanded in the second turbine, the liquid fraction at the end of this second expansion forming a part of the liquefied natural gas produced by the process.
  • At least part of the gaseous fraction from step b) is put, for example, in counter-current contact with the liquid fraction from step e), the resulting liquid fraction being sent to step f) and the resulting gas fraction being combined with the fraction gas from step e) to form at least in part a gas fraction rich in nitrogen which is evacuated.
  • the present invention also relates to an apparatus for liquefaction of a natural gas according to the method described above, comprising a natural gas inlet pipe and preferably a conduit for a recycled gas, said conduits being connected to a device allowing to cool natural gas, a conduit allowing the passage refrigeration fluid, inside the device, an outlet duct connected to the cooled natural gas device and in the form of dense phase, a compression and condensation circuit.
  • the duct is separated in two under conduits, said first under conduit being connected to a first expansion device, said second under conduit being directly connected to a refrigeration device, having a gas fraction outlet pipe natural refrigerated, said duct being connected to an expansion means, said duct being connected to a expansion device, said expansion devices being connected to a means for separation of the expanded natural gas fractions from devices by conduits respectively, said separation means being provided with at least one vapor phase evacuation pipe and minus a liquefied natural gas discharge pipe.
  • the means capable of relaxing natural gas in the form of a phase dense consists of at least one expansion turbine of which at least one elements is made of a material which is not very conductive of heat.
  • the present invention offers many advantages over to the methods usually used in the prior art. Indeed, the fact of work at an initial pressure value for the gas greater than values used by the processes mentioned in the prior art allows reduce the energy required for liquefying natural gas.
  • Figure 1 shows a block diagram of a process used according to the prior art for liquefying a natural gas, for example.
  • the liquefaction process involves a precooling cycle which allows the mixture used in the refrigeration cycle to be condensed main.
  • the pre-refrigeration cycle and the main refrigeration cycle use a mixture of fluids as refrigerant.
  • a mixture in vaporizing is likely to refrigerate and liquefy the gas under pressure.
  • the mixture is compressed, condensed into exchanging heat with the surrounding environment, such as water or air, available and recycled.
  • Natural gas comes under pressure through line 1. It then passes in the exchanger E1 in which it is liquefied and cooled. At the exit of exchanger E1, liquefied natural gas is expanded to a value of pressure close to atmospheric pressure by passing through a expansion valve V1 and then discharged through line 2.
  • Natural gas is cooled by a permanent gas circulating in the refrigeration cycle consisting of a turbine T 1 , a duct 4 connecting the turbine T 1 to the exchanger E1, and a duct 5 allowing passage permanent gas from the exchanger to a series of compressors and cooling means arranged in cascade K1, C1, K2, C2 for example.
  • the permanent gas circulating in the refrigeration cycle is compressed in the compression stage K1, cooled by passage through the cooling means C1 and then passes into the compression stage K2 in which it is compressed to be subsequently cooled by passage through the cooling stage C2.
  • the permanent gas, thus compressed and cooled is sent via line 3 to the turbine T 1 in which it undergoes expansion and from which it emerges cooled before being sent to the exchanger E1 via line 4.
  • the permanent gas thus refrigerated cools the natural gas when brought into contact in the exchanger E1. At the outlet of this exchanger and after having cooled the natural gas, the permanent gas is sent again and recycled in the compression and cooling stages via the conduit 5.
  • Such a cycle is used for small capacity units, in particular because of its simplicity. However, it is recognized that its performance is significantly lower than a cycle using a mixture of refrigerants. In addition, it involves the recirculation of a very large flow of refrigerant gas.
  • the principle implemented according to the invention described below consists, from a dense phase natural gas, to arrive at least in part at its liquefaction without phase transition, i.e. at least part of the liquefaction process takes place without phase transition during of which there would be coexistence between two phases of natures different. So, throughout the liquefaction process the passage of the dense phase to the liquid phase takes place continuously, a phase transition involving discontinuous passage.
  • the method relies on the implementation, essentially of at least two stages, the first consisting in bringing natural gas into phase dense and the second to produce a trigger with energy supply mechanical, for example a substantially isentropic expansion, making pass the natural gas in dense phase in liquid phase.
  • the gas arrives via the conduit 7 (FIG. 3A) in the gas phase, in a thermodynamic state represented by the point G1 (FIG. 3B), in an exchanger E2 in which it is precooled to a given temperature, in contact with a coolant from a refrigeration cycle R1.
  • Natural gas is present at the outlet of the exchanger E2, in dense phase, at point G2 (Fig.3B). It is then transmitted from the exchanger E2 to the turbine T 4 in which it is expanded by the conduit 15. After passing through the turbine T 4 , it is at least partly in the liquid phase at point G3.
  • the transformation from the dense phase to the liquid phase is carried out by expansion with supply of mechanical energy and without phase transition.
  • the liquid phase obtained at point G3 after expansion is, for example, a saturated liquid phase.
  • a gaseous fraction or steam which, after heat exchange, can be recycled or used otherwise. It is, for example, used as fuel on the site of the liquefaction facility.
  • the process is illustrated in a coordinate diagram pressure (P) and temperature (T) shown in Figure 3B.
  • P coordinate diagram pressure
  • T temperature
  • the gas phase domain is delimited by the vapor branch v (dew curve) of the two-phase domain and the isentrope s passing through the critical point C.
  • the domain of the dense phase is delimited on the one hand by the isentrope s and on the other hand by the isobaric p passing by the critical point C.
  • the domain of the liquid phase is delimited by a leaves by the isobar p and by the liquid branch I (bubble curve) of the domain two-phase.
  • the natural gas to be liquefied is initially in a gas phase state represented by a point G1 at a temperature T G1 and at a pressure P G1 . It is then cooled in a substantially isobaric manner so as to bring it into a dense phase state represented by the point G2, at a pressure and a temperature respectively P G2 and T G2 .
  • the transition from G1 to G2 takes place, for example, continuously, without phase transition, passing through the point F1 of the isentrope p delimiting the gas phase domain from the dense phase domain.
  • the natural gas in dense phase, point G2 is then expanded in a substantially isentropic manner to pass it into a liquid phase state, and preferably in a saturated liquid phase state represented by a point G3 located, for example, on the liquid branch I of the two-phase domain, corresponding to temperature and pressure values T G3 and P G3 .
  • the value of the pressure P G3 is preferably substantially equal to that of the atmospheric pressure.
  • the transition from the state represented by the point G2 to the state represented by the point G3 is effected by passing through the point F2 of the isobare p delimiting the dense phase domain from the liquid phase domain, continuously without phase transition, that is to say without coexistence between two different phases.
  • the trigger can be continued in the two-phase field by generating a vapor fraction or carbonated.
  • the temperature at the end of the refrigeration stage preceding the stage of trigger is between 165 and 230K.
  • FIG. 3C illustrates the application of the process to the liquefaction of a gas natural.
  • Natural gas arrives via a pipe 7 to an exchanger E2 under a pressure greater than at least the critical pressure value of methane, in which it is cooled to a temperature, for example between 165 K and 230 K.
  • This step of pre refrigeration of the gas is ensured, for example, by a fraction of the natural gas withdrawn before it enters an exchanger E2 via a pipe 8 which transfers this fraction withdrawn to an expansion turbine T 2 .
  • the withdrawn fraction is cooled during expansion, carried out and operated in the gas phase in the turbine T 2 , it is then sent to the exchanger E2 by a conduit 9.
  • the withdrawn and cooled gaseous fraction thus acts as an agent cooling and lowers the temperature of the natural gas entering the exchanger E2. Any external refrigerant with characteristics allowing to cool a gas can replace the fraction of natural gas withdrawn and cooled.
  • the natural gas thus leaves the exchanger E2 cooled in the "dense" phase by a conduit 10.
  • a fraction of this "dense" phase is sent directly by a conduit 11, for example, to an expansion turbine T 3 .
  • a mixture composed mainly of liquid phase is obtained.
  • the mixture is discharged through a line 12, at a pressure close to atmospheric pressure, from the turbine T 3 to a separator flask B1 in which the liquid and gaseous fractions are separated.
  • the gaseous fraction taken from the balloon B1 is sent through a line 13 into an exchanger E3.
  • the fraction of natural gas cooled in the "dense" phase from the exchanger E2 which has not been sent to the turbine T 3 passes through a pipe 14 in an exchanger E3 in which it is refrigerated by heat exchange with the gaseous fraction arriving via line 13.
  • the natural gas thus refrigerated leaves the exchanger E3 at a temperature lower than the temperature which it has at the inlet of this exchanger, for example at a temperature close to the temperature of the arriving gaseous fraction via line 13. It is then sent via line 15 to a turbine T 4 in which it is expanded. At the outlet of the turbine T 4 , the majority mixture is obtained in the liquid phase which is sent via a line 16 to the separator flask B1.
  • the two liquid phase fractions collected in the flask B1 form the liquefied natural gas discharged through a line 17.
  • the gaseous fraction coming from the separator flask B1 passes into the exchanger E3 by a conduit 13 and is sent to the exchanger E2 by a conduit 18 from which it emerges at a temperature close to the inlet temperature of the natural gas to be liquefied. It is then sent to a compression stage K3 via a conduit 19.
  • the gaseous fraction is cooled by heat exchange with the ambient medium, water or air, available in a heat exchanger C3, then it is mixed with a gaseous fraction coming from the expansion through the turbine T 2 of the gaseous part initially removed before the exchanger E2, said gaseous fraction coming from the exchanger E2 by a conduit 20 connected and opening into the conduit 19, for example between the exchanger C3 and a compression stage K4.
  • the gas mixture thus obtained is compressed in the compression stage K4 and then cooled by heat exchange with the ambient medium, water or air available.
  • the gas mixture thus compressed and cooled is recycled via line 21 and mixed with the natural gas to be liquefied arriving via line 7.
  • Each of the compression stages K3 and K4 can be advantageously replaced by a succession of compression stages, the gas mixture leaving a compression stage being cooled by heat exchange with the surrounding environment, water or air, available, before to be sent to the next floor so as to bring the compression closer operated by an isothermal compression carried out at a neighboring temperature the ambient temperature, water or air, available.
  • the critical pressure of the mixture forming the natural gas is higher than the critical methane pressure.
  • the pressure at which is carried out step a) is preferably greater than the pressure critical of said mixture.
  • the pressure at which step a) is carried out is also, from preferably greater than the defined cricondenbar for a mixture like being the pressure above which two phases cannot coexist.
  • the fraction of natural gas in the "dense" phase which is not expanded in the turbine T 3 is cooled in the exchanger E3 to a temperature close to the final temperature of the natural gas liquefied product.
  • the fraction of natural gas expanded in the expansion turbine T 3 represents a majority fraction of the natural gas present at the inlet, this fraction preferably being greater than two thirds of the natural gas present at the inlet of the exchanger E3 and arriving via line 10.
  • the expansion work used to relax the natural gas is, for example, recovered in the turbines T 3 and T 4 and used, for example, to drive the compression stages K3 and K4 and / or, in the case of the diagram in the figures 5 and 6, the compression stages K5 and K6.
  • the additional mechanical energy that may be required is supplied, for example, by a steam turbine or, preferably, by a gas turbine.
  • step a) By increasing the pressure level at which step a) is carried out, it is possible to reduce the additional mechanical energy required to liquefy natural gas.
  • the method according to the invention is all the more advantageous since the pressure at which step a) is carried out is high.
  • the pressure used must be at least equal to the critical pressure of methane (4.6 MPa) and, preferably greater than the cricondenbar of the mixture which constitutes the gas natural to liquefy. It is situated, advantageously in an interval for example between 7 and 20 MPa.
  • the quantity of gaseous phase recycled after the expansion carried out at during step c is preferably between 165 K and 230K.
  • hydrocarbons When natural gas contains heavier hydrocarbons than methane, these hydrocarbons are, for example, at least in part separated from natural gas before the liquefaction operation, in particular for avoid any risk of crystallization during liquefaction.
  • the Hydrocarbons heavier than methane cannot be condensed by refrigeration. It was discovered that, in this case, they are advantageously separated by an adsorption step on an adsorbent constituted for example by an alumina, a zeolite or an activated carbon.
  • the adsorbent is used, for example, in at least two beds fixed operating in parallel.
  • a bed operates, for example, in adsorption while another bed is operating in desorption.
  • Desorption is carried out, by for example, by decreasing the pressure and / or increasing the temperature. Hydrocarbons heavier than methane which must be separated, attach to the adsorbent during the adsorption step, then they are separated during the desorption step.
  • step a Another way to proceed when natural gas contains heavy hydrocarbons, consists, during step a) in cooling the gas natural at a temperature such that after a relaxation substantially isentropic having brought the gas to a pressure below the cricondenbar of the mixture, a liquid phase is formed by condensation retrograde.
  • the expanded mixture is then cooled to a pressure substantially constant.
  • the liquid phase comprising the hydrocarbons heavier than methane, to be separated, is then removed after the expansion operation and / or during the subsequent cooling of the mixture operated at a substantially constant pressure.
  • the gas can be compressed, at the by means of a compression step carried out under conditions also as close as possible to that of isothermal compression using compression stages alternating with cooling stages, the cooling being carried out using a cooling fluid, water or air available, for example at the liquefaction site.
  • such a compression step can become necessary when the gas pressure at the head of the well becomes too low, for example, after a period of exploitation of the gas field natural.
  • the natural gas to be liquefied contains nitrogen, and when this is necessary, it is possible to at least partially separate this nitrogen.
  • Natural gas is sent to the exchanger E2 via line 7. A the end of the cooling step in the exchanger E2, natural gas comes out as a "dense" phase. The fraction of this "dense" phase can be relaxed directly, by at least two relaxation steps described below.
  • a first fraction of the dense phase is sent via the conduit 11 from the outlet of the exchanger E2 to a turbine T 31 in which it is expanded.
  • the mixture obtained by expansion is evacuated via a pipe 30 from the turbine T 31 to a separator flask B2 in which the liquid and gaseous fractions of the mixture are separated.
  • the gaseous fraction is, for example, sent or recycled through a conduit 31 in the exchanger E3.
  • the liquid fraction separated in the separator flask B2 is depleted in nitrogen, then discharged through a conduit 32 to a turbine T 32 where it is expanded and from which it emerges in the form of a liquid-vapor mixture.
  • this liquid-vapor mixture obtained is sent to the base or lower part of a contactor S1 via a pipe 35.
  • the fraction of natural gas cooled in dense phase from the exchanger E2 and not diverted to the turbine T 31 is sent through a pipe 14 to the exchanger E3. It is refrigerated in this exchanger by heat exchange with the gaseous fraction coming from the duct 31. At the outlet of the exchanger E3, the fraction in dense phase is at a temperature below its initial temperature of entry into the exchanger E3, substantially close of the temperature of the gaseous fraction arriving via the pipe 31.
  • This dense phase fraction coming from the exchanger E3 is sent by a pipe 15, in a turbine T 4 , in which it is expanded.
  • the liquid-vapor mixture mainly composed of liquid phase obtained after expansion at the outlet of the turbine T 4 is sent to the head of the contactor S1, upper part of the contactor, through a conduit 36.
  • the liquid phase leaving the turbine T 4 is relatively concentrated in nitrogen.
  • it is contacted against the current with the gaseous fraction arriving at the base of the contactor S1 via the conduit 35 whose composition is close to equilibrium with a liquid phase relatively poor in nitrogen.
  • the liquid phase which descends becomes depleted in nitrogen and the gaseous phase which rises is enriched in nitrogen. It is thus possible to obtain, at the base of the contactor S1, a liquid fraction relatively poor in nitrogen and at the head of the contactor S1 a gaseous fraction relatively rich in nitrogen.
  • the liquid fraction collected at the base of the contactor S1 forms the liquefied natural gas discharged through a conduit 38.
  • the gaseous fraction collected at the head of the contactor S1 forms the gaseous fraction concentrated in nitrogen which is separated from the natural gas.
  • This gaseous fraction concentrated in nitrogen is removed by a conduit 34 and sent to an exchanger E4 from which it emerges through a conduit 37.
  • the gaseous fraction concentrated in nitrogen is heated by heat exchange with a fraction of natural gas derived from the natural gas introduced arriving via a conduit 33 connecting directly the conduit 7 for introducing natural gas to the exchanger E4.
  • This fraction of natural gas directly derived from the introduction conduit 7 is cooled in the exchanger E4, then expanded through an expansion valve V3 located on the conduit 36 connecting the exchanger E4 to the contactor S1.
  • the fraction of natural gas derived and expanded is then mixed with the liquid-vapor mixture coming from the turbine T 4 , and sent to the contactor S1, the mixing of the two liquid vapor fractions being carried out at the level of the conduit 36.
  • the contactor S1 is formed for example of a column element with packing or column trays.
  • the number of theoretical stages of the contactor S1 is for example 3 or 4.
  • a first fraction f1 of this natural gas is cooled by the exchangers E2 and E3 to a temperature of 122 K.
  • the natural gas is thus found at the outlet of the exchanger E3 in a "dense" phase state. It is then at least partially liquefied by expansion in the turbine T 4 , for example, at atmospheric pressure and is then introduced through the conduit 16 at the head of the contactor S1.
  • a second fraction f2 taken upstream of the exchanger E2 is cooled to 185 K by a substantially isentropic expansion in the turbine T 2 to the vicinity of its dew pressure.
  • This cooled and expanded fraction is then introduced via line 9 into the exchanger E2 where it heats up against the current with the first fraction f1.
  • the fraction f2 passes through a train of compressors refrigerated by the ambient medium K4, C4, in which it is compressed and cooled, then is mixed with the natural gas to be liquefied introduced by the conduit 7.
  • a third fraction f3 is taken and cooled, for example, to 117 K by a substantially isentropic expansion in a turbine T 31 .
  • the gaseous fraction is separated from the gas / liquid mixture obtained by expansion of the fraction f3 in the cylinder B2, and introduced by the conduit 31 in the exchanger E3, then by the conduit 18 in the exchanger E2 where it heats up against current with the first fraction f1.
  • the fraction f3 passes through a train of compressors K3, C3, refrigerated, for example, by the ambient medium and is then mixed with the second fraction f2 upstream of the train of compressors K4, C4 also refrigerated. , for example, by the surrounding environment.
  • the liquid fraction coming from the balloon B2 is expanded by passing through the turbine T 32 at atmospheric pressure and introduced into the lower part, for example, at the bottom of the contactor S1.
  • the vapor fraction or gaseous fraction is enriched in nitrogen.
  • the vapor fraction contains 66% by mass of nitrogen and liquefied natural gas 1.3% by mass of nitrogen. This vapor fraction is warmed up to room temperature with a fraction f4 of the natural gas to be treated, is introduced at the top of the contactor before being discharged.
  • fractions f1, f2, f3 and f4 are chosen so that the thermal approaches to the exchangers are minimal.
  • the methane losses in the purged gas are 3.5%.
  • step b) The relaxation carried out during step b) is accompanied by a significant variation in temperature which is, for example, greater than 50 ° C. In the case where the expansion is carried out in two or more successive turbines, this results in a relatively large difference between the inlet and outlet temperatures for each turbine.
  • the trigger is operated in the "dense" or liquid phase. Thermal exchanges between the fluid being expanded and the elements of the turbine can, under these conditions, reduce the effectiveness of the trigger.
  • These elements can be coated metallic components a thermally insulating layer. These elements, and in particular the rotor, can also be made of a composite material poor conductor of heat.
  • the heat exchanges carried out during steps a) and d) are carried out in heat exchangers operating against the current.
  • These heat exchangers are, for example, pass exchangers multiple and are preferably constituted by plate heat exchangers.
  • These plate exchangers can be, for example, heat exchangers brazed aluminum. It is also possible to use heat exchangers stainless steel with plates welded together.
  • the channels in which the fluids participating in the exchange circulate heat can be obtained by different means by arranging between the plates of the corrugated intermediate plates, forming the plates, for example by explosion, by grooving the plates, for example by chemical etching.
  • step e) The heat exchange carried out during step e) is then carried out with a temperature difference on the coldest side of the heat exchanger preferably less than 5K and a temperature difference on the hottest side of the exchanger preferably less than 10K.
  • stage a) of refrigeration by means of an external cycle operating with a mixture of refrigerants.
  • the operating principle of the process in this case is illustrated, for example in FIG. 5.
  • the first stage of refrigeration of natural gas is then carried out in the exchanger E2, such as a plate exchanger, not by an exchange thermal with a gaseous fraction refrigerated by expansion as it is described above, but. with a mixture of refrigerants which vaporizes in the exchanger E2.
  • the exchanger E2 such as a plate exchanger
  • the refrigerant mixture comes from cycle A comprising, by example, a set of pipes, compressors, exchangers and valves as described below.
  • the refrigerant mixture is vaporized at two pressure levels which can be successive to widen the temperature range for which performs the refrigeration.
  • This mixture is, for example, introduced into the exchanger E2 by a conduit 27 which separates into two conduits 27a and 27b.
  • a first part mixture of refrigerants in liquid phase is first evacuated by a conduit 23 extending conduit 27a from exchanger E2 to a first expansion valve V20, in which it is vaporized, for example, at a temperature between 238 and 303K, pass through the exchanger E2 and comes out in gaseous or vapor form to be sent to a compressor K6 through a pipe 24.
  • a second part of the mixture passes through the sub-conduit 27b, then is evacuated from the exchanger E2 to a valve V30 located on a conduit 25 extending the sub duct 27b.
  • the mixture is expanded by the valve V30 up to a pressure close to atmospheric pressure and vaporized, for example, at a temperature between 173 and 238K.
  • the vapor phase thus obtained is sent from the E2 exchanger to the inlet of a K5 compressor, then cools in a C5 exchanger located after the compressor K5 and mixed with the steam fraction arriving through the pipe 24.
  • the vapor phase mixture thus obtained is then compressed in the K6 compressor, cooled and condensed by passing through an exchanger C6 before being sent via line 27 into the exchanger E2, where it is sub-cooled before being relaxed and vaporized.
  • Natural gas arrives via line 7 and leaves the exchanger E2 cooled by a line 11, it has, at the outlet of exchanger E2, a temperature close to, for example, 178K in the form of a mixture. Most of this mixture passes through a turbine T 3 in which it is expanded and from which it emerges in the form of a liquid-vapor mixture which is then sent by a conduit 12 to the base of a contactor S1.
  • the other part of the natural gas having passed through the turbine T 3 passes directly from the exchanger E2 to a plate exchanger E3 by a conduit 14 in which it is cooled for example by exchange with the fraction in vapor phase coming from the contactor S1 by a conduit 13, up to a temperature close to the final temperature of the liquefied natural gas produced.
  • the gas fraction cooled in the exchanger E3 leaves this exchanger through a conduit 15 and expanded through an expansion valve V4.
  • the liquid fraction obtained by expansion is sent to the top of the contactor S1.
  • this liquid phase is depleted in nitrogen, while the vapor phase fraction introduced at the bottom of the contactor S1 goes back into the contactor, enriched with nitrogen. Fraction in the vapor phase which leaves the contactor S1 is thus charged with nitrogen, this which thus allows most of the nitrogen contained to be removed initially in natural gas.
  • the nitrogen-rich gas fraction passes through the exchanger E3, then via the conduit 18 in the exchanger E2 from which it emerges by a duct 19.
  • the contactor S1 can be constituted for example by a column with trays or a packed column.
  • the lining may advantageously be of the "structured" type.
  • V20, V30 and V4 expansion valves can be replaced by in whole or in part by drive expansion turbines.
  • the E2 and E3 exchangers can be made with materials and / or different assembly methods. It is also possible to carry out all of the heat exchanges in a heat exchanger single plate.
  • K5 and K6 compressors can each have a series of floors. Between two successive stages, it is possible to plan a stage intermediate cooling.
  • the low-pressure gas fraction discharged through line 19 can be at least partially recompressed and recycled. It is clear, however, that if the gaseous fraction thus obtained can be used at low pressure, without be recycled, it is possible to significantly reduce costs investment and the necessary operating costs.
  • the natural gas leaving the exchanger E2 via the conduit 11 undergoes a first expansion in the turbine T 31 .
  • a liquid fraction is collected by a balloon B3 then evacuated by the conduit 42 preferably located in the lower part of this balloon towards a turbine T 32 where it undergoes a second expansion.
  • a gaseous fraction relatively rich in nitrogen sent by a pipe 40 in a turbine T 4 where it is expanded before being sent into the contactor S1, preferably in its lower part.
  • the expanded mixture obtained is evacuated by a conduit 43 and separated in a flask 84 into a liquid fraction depleted in nitrogen which is evacuated by a conduit 45 located in the lower part of the flask B, preferably , and which constitutes part of the liquefied natural gas produced and a gaseous fraction taken from the upper part of the balloon relatively poor in nitrogen sent by a conduit 44 to the exchanger E3, then by the conduit 18 to the exchanger E2 from where it comes out through the conduit 19.
  • the conduit 19 is connected to a compressor K3 which recompresses, for example, said gaseous fraction relatively poor in nitrogen before passing through an exchanger C3 where it is cooled with the cooling fluid, which can be of the water or air.
  • the compressor K3 preferably comprises several compression stages between which are placed, for example, cooling stages.
  • Natural gas under pressure leaving the exchanger E3 via the pipe 15 is, for example, relaxed in an expansion valve V11 before being sent at the head of contactor S1.
  • the non-recycled fraction is evacuated via conduit 49.
  • Via conduit 47 arrives in the exchanger E4 a fraction of the pressurized natural gas that is cooled in the exchanger E4 and exits through the conduit 48 at a temperature close to the final temperature of the LNG produced. Said fraction is then relaxed to through valve V10 and sent to the head of contactor S1.
  • a liquid fraction is collected which is mixed with the liquid fraction arriving via line 45 to form the liquefied natural gas produced, which is discharged through line 50.

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Claims (24)

  1. Verfahren zur Verflüssigung eines Naturgases, insbesondere eines Erdgases, in Kombination die folgenden Stufen umfassend:
    a) man kühlt das Erdgas auf einen Druck, der wenigstens höher oder gleich dem kritischen Druck des Methans und bei einer Temperatur derart ist, daß dieses Erdgas sich in dichter Phase am Austritt aus dieser Kühlstufe darstellt und man dieses Gas alternativ mit einer recyclierten gasförmigen Fraktion vermischt,
    a') man trennt das gekühlte Erdgas in dichter Phase in zwei Fraktionen, eine erste Mehrheitsfraktion (11) und eine zweite Restfraktion (14),
    b) man entspannt und man verflüssigt die erste aus der Stufe a) kommende Mehrheitsfraktion über eine Vorrichtung (T3), die so ausgebildet ist, daß sie den Druck des Erdgases gemäß einer Entspannung unter Lieferung mechanischer Energie derart vermindert, daß am Austritt aus dieser Stufe b) eine flüssige und eine gasförmige Fraktion erhalten werden,
    c) man trennt (B1) die flüssige Fraktion und die gasförmige Fraktion (13), die während der Stufe b) erhalten wurden,
    d) die gasförmige aus der Stufe c) resultierende Fraktion (13) wird thermisch (E3) mit der zweiten nicht entspannten Restfraktion (14) des Erdgases ausgetauscht, wobei diese nicht entspannte und gekühlte Fraktion am Ende dieses Vorgangs durch eine Entspannungsvorrichtung (T4) entspannt wird, indem ein Flüssigkeits-Dampfgemisch gebildet wird, welches in eine flüssige Fraktion und eine gasförmige Fraktion getrennt wird (B1),
    e) man vereinigt die flüssigen aus den Stufen c) und d) stammenden Fraktionen zur Bildung des verflüssigten Erdgases und
    f) die gasförmigen aus den Stufen c) und d) stammenden Fraktionen bei Stufe a) werden wenigstens zum Teil rekomprimiert und recycliert und bilden so diese in die Stufe a) recyclierte Gasfraktion, und die nicht-recyclierten Fraktionen werden abgezogen.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die erste (11) entspannte Mehrheitsfraktion bevorzugt um zwei Drittel größer als das Erdgas in dichter Phase, das aus Stufe a) stammt, ist.
  3. Verfahren zur Verflüssigung eines Naturgases, insbesondere Erdgases nach Anspruch 2, dadurch gekennzeichnet, daß die Entspannung der flüssigen während der Stufe b) erhaltenen Phase fortgesetzt wird, bis eine gasförmige Fraktion auftritt, wobei man dann die folgenden Stufen vornimmt:
    man trennt die flüssige Fraktion und die gasförmige Fraktion während der Stufe c),
    die gasförmige aus der Stufe c) resultierende Fraktion wird thermisch mit einer nicht-entspannten Fraktion des Erdgases während der Stufe d) ausgetauscht, wobei diese nicht-entspannte Fraktion am Ende dieses Wärmeaustauschvorgangs während der Stufe e) entspannt wird, indem ein Flüssigkeits-Dampfgemisch gebildet wird, das in eine flüssige Fraktion und eine gasförmige Fraktion geteilt wird,
    man vereinigt die flüssigen aus den Stufen c) und e) stammenden Fraktionen zur Bildung des verflüssigten Erdgases und
    man rekomprimiert und man recycliert wenigstens zum Teil die gasförmigen aus den Stufen c) und e) stammenden Fraktionen zur Stufe a).
  4. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 3, dadurch gekennzeichnet, daß man eine Turbine als Mittel zur Entspannung des Erdgases aus dem Zustand in dichter Phase in den Zustand in flüssiger Phase verwendet.
  5. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 4, dadurch gekennzeichnet, daß während der Stufe a) man das Erdgas durch Wärmeaustausch kühlt, indem man eine gasförmige Fraktion verwendet, die aus diesem Erdgas stammt, wobei diese gasförmige Fraktion in einer Turbine (T2) entspannt wird, wobei diese gasförmige entspannte Fraktion wenigstens zum Teil in einer Kompressionsstufe rekomprimiert und recycliert wird.
  6. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 5, dadurch gekennzeichnet, daß man wenigstens eine recyclierte gasförmige Fraktion komprimiert, indem wenigstens zwei Stufen zum Einsatz kommen, daß das Gas am Austritt aus jeder der Kompressionsstufen durch ein verfügbares Medium aus der Umgebung gekühlt wird.
  7. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 6, dadurch gekennzeichnet, daß während der Stufe a) man das Erdgas durch Verdampfung eines Gemisches aus Kühlmitteln kühlt.
  8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß das Gemisch aus Kühlmitteln entspannt und auf wenigstens zwei unterschiedlichen Druckniveaus verdampft wird.
  9. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 8, dadurch gekennzeichnet, daß das Erdgas schwere Kohlenwasserstoffe umfaßt, man die schwersten in dem zu verflüssigenden Erdgas enthaltenen Kohlenwasserstoffe vermittels einer Adsorptionsstufe vor der Stufe a) trennt.
  10. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 9, dadurch gekennzeichnet, daß man die Stufe a) bei einem Druck höher als den kritischen Druck des zu verflüssigenden Erdgases realisiert.
  11. Verfahren zur Verflüssigung eines Erdgases nach Anspruch 10, dadurch gekennzeichnet, daß man die Stufe a) bei einem Druck höher als dem Cricondenbar des zu verflüssigenden Erdgases realisiert.
  12. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 10 und 11, dadurch gekennzeichnet, daß man die Stufe a) bei einem Druck zwischen 7 und 20 MPa durchführt.
  13. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10, dadurch gekennzeichnet, daß die Temperatur des Erdgases am Austritt aus der Stufe a) zwischen 165 K und 230 K liegt.
  14. Verfahren zur Verflüssigung eines Erdgases nach Anspruch 3, dadurch gekennzeichnet, daß die am Austritt aus der Stufe b) erhaltene gasförmige Fraktion größer oder gleich 20% ist.
  15. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10, dadurch gekennzeichnet, daß das Erdgas schwerere Kohlenwasserstoffe als Methan umfaßt, man diese Kohlenwasserstoffe wenigstens zum Teil während einer vorherigen Stufe trennt, die bei einem Druck niedriger als dem Druck der Stufe a) durchgeführt wurde.
  16. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10 und 13 bis 15, dadurch gekennzeichnet, daß man das Erdgas während der Stufe a) bis auf eine Temperatur derart kühlt, daß nach der Entspannung eine flüssige an Kohlenwasserstoffen schwerer als das Methan konzentrierte Fraktion erzeugt wird, wobei diese flüssige Fraktion dann abgetrennt wird.
  17. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10 und 13, dadurch gekennzeichnet, daß die Stufe b) durch Entspannung in einer Turbine durchgeführt wird, bei der wenigstens eines ihrer Elemente aus einem Material hergestellt ist, das Wärme gering leitet.
  18. Verfahren zur Verflüssigung eines Erdgases nach Anspruch 17, dadurch gekennzeichnet, daß der Rotor der Turbine aus einem Wärme wenig leitenden Verbundmaterial hergestellt ist.
  19. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10 und 13 und 17, dadurch gekennzeichnet, daß die Wärmeaustauschvorgänge während der Stufen a) und d) in im Gegenstrom arbeitenden Wärmeaustauschern realisiert werden.
  20. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10 und 13 und 17, dadurch gekennzeichnet, daß man den Wärmeaustausch der Stufe d) durchführt, indem man das Erdgas in einen Wärmeaustauscher leitet, der eine Temperaturabweichung auf der kältesten Seite des Wärmeaustauschers von weniger als 5K und eine Temperaturabweichung auf der heißesten Seite des Wärmeaustauschers von weniger als 10K zeigt.
  21. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10 und 13 und 17, dadurch gekennzeichnet, daß man die Entspannung während der Stufe b) vermittels wenigstens zwei aufeinanderfolgender Turbinen vornimmt, wobei das Flüssigkeits-Dampfgemisch aus der ersten Teilentspannung in eine gasförmige Fraktion und eine flüssige Fraktion getrennt wird, wobei diese gasförmige Fraktion zur Realisierung der Stufe d) geschickt wird und diese resultierende flüssige Fraktion in der zweiten Turbine entspannt wird, wobei die flüssige Fraktion am Austritt aus dieser zweiten Entspannung einen Teil des verflüssigten durch das Verfahren erzeugten Erdgases bildet.
  22. Verfahren zur Verflüssigung eines Erdgases nach einem der Ansprüche 2 bis 10 und 13 und 17, dadurch gekennzeichnet, daß wenigstens ein Teil der gasförmigen aus der Stufe b) stammenden Fraktion im Gegenstrom mit der flüssigen aus der Stufe e) stammenden Fraktion kontaktiert wird, wobei die flüssige resultierende Fraktion mit der flüssigen aus der Stufe b) stammenden Fraktion zur Bildung des verflüssigten Erdgases vereinigt wird und die gasförmige resultierende Fraktion mit der gasförmigen aus der Stufe e) stammenden Fraktion vereinigt wird, um wenigstens zum Teil eine an Stickstoff reiche Fraktion, die abgezogen wird, zu bilden.
  23. Vorrichtung zur Verflüssigung eines Erdgases nach dem die Merkmale eines der vorhergehenden Ansprüche umfassenden Verfahrens, eine Leitung (7) zur Zuführung des Erdgases und bevorzugt eine Leitung (21) eines recyclierten Gases umfassend, wobei diese Leitungen mit einer Vorrichtung (E2) verbunden sind, die es ermöglicht, das Erdgas zu kühlen; eine Leitung, die den Durchgang eines Kühlfluids (9) im Inneren der Vorrichtung (E2) ermöglicht, eine Austrittsleitung (10), die mit der Vorrichtung (E2) für das gekühlte Erdgas verbunden ist und welches in dichter Phase vorliegt; ein Kompressions- und Kondensationskreis (K3, C3, ...) dadurch gekennzeichnet, daß die Leitung (10) in zwei Nebenleitungen (11; 14) unterteilt ist, wobei die erste Nebenleitung (11) mit einer ersten Entspannungsvorrichtung (T3), die zweite Nebenleitung (14) direkt mit einer Kühlvorrichtung (E3) verbunden ist, die eine Austrittsleitung (15) für die Fraktion des gekühlten Erdgases umfaßt, diese Leitung (15) mit einer zweiten Entspannungsvorrichtung (T4) verbunden ist, diese Entspannungsvorrichtungen (T3, T4) mit einem Trennmittel (B1) der Fraktionen des entspannten Erdgases, die aus den Entspannungsvorrichtungen (T3, T4) stammen jeweils über Leitungen (12, 16) verbunden sind und wobei dieses Trennmittel (B1) mit wenigstens einer Leitung (13) zum Abzug der Dampfphase und wenigstens einer Leitung (17) zum Abzug des verflüssigten Erdgases versehen ist.
  24. Vorrichtung zur Verflüssigung eines Erdgases nach Anspruch 23, dadurch gekennzeichnet, daß diese Entspannungsvorrichtungen gebildet werden durch wenigstens eine Entspannungsturbine, bei der wenigstens eines ihrer Elemente aus einem Wärme gering leitenden Material hergestellt ist.
EP95905171A 1993-12-30 1994-12-26 Verfahren und vorrichtung zur verflüssigung von erdgas Expired - Lifetime EP0687353B1 (de)

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FR9315924A FR2714720B3 (fr) 1993-12-30 1993-12-30 Procédé et appareil de liquéfaction d'un gaz naturel.
FR9315924 1993-12-30
FR9402024A FR2714722B1 (fr) 1993-12-30 1994-02-21 Procédé et appareil de liquéfaction d'un gaz naturel.
FR9402024 1994-02-21
PCT/FR1994/001535 WO1995018345A1 (fr) 1993-12-30 1994-12-26 Procede et appareil de liquefaction d'un gaz naturel

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KR960701346A (ko) 1996-02-24
CA2156249A1 (fr) 1995-07-06
KR100356093B1 (ko) 2003-01-29
FR2714722A1 (fr) 1995-07-07
FR2714722B1 (fr) 1997-11-21
US5651269A (en) 1997-07-29
JP3602130B2 (ja) 2004-12-15
AU1388395A (en) 1995-07-17
NO303850B1 (no) 1998-09-07
EP0687353A1 (de) 1995-12-20
AU684885B2 (en) 1998-01-08
CA2156249C (fr) 2006-03-21
NO953377D0 (no) 1995-08-29
WO1995018345A1 (fr) 1995-07-06
JPH08507364A (ja) 1996-08-06
NO953377L (no) 1995-08-29
ES2126876T3 (es) 1999-04-01

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