EP0661505B1 - Process and installation for the liquefaction of a gas - Google Patents

Process and installation for the liquefaction of a gas Download PDF

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Publication number
EP0661505B1
EP0661505B1 EP94402787A EP94402787A EP0661505B1 EP 0661505 B1 EP0661505 B1 EP 0661505B1 EP 94402787 A EP94402787 A EP 94402787A EP 94402787 A EP94402787 A EP 94402787A EP 0661505 B1 EP0661505 B1 EP 0661505B1
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EP
European Patent Office
Prior art keywords
turbine
gas
cycle
compression
air
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EP94402787A
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German (de)
French (fr)
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EP0661505A1 (en
Inventor
Bernard Darredeau
Philippe Fraysse
Corinne Garot
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Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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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
    • F25J3/04—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 for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04278—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using external refrigeration units, e.g. closed mechanical or regenerative refrigeration units
    • 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
    • F25J3/04—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 for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04296—Claude expansion, i.e. expanded into the main or high pressure column
    • 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
    • F25J3/04—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 for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04339—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of air
    • F25J3/04345—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of air and comprising a gas work expansion 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
    • 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
    • F25J3/04—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 for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04351—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
    • F25J3/04357—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen and comprising a gas work expansion 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
    • 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
    • F25J3/04—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 for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
    • 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
    • F25J3/04—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 for air
    • F25J3/04406—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 for air using a dual pressure main column system
    • F25J3/04412—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 for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • 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
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S62/00—Refrigeration
    • Y10S62/939—Partial feed stream expansion, air

Definitions

  • the present invention relates to a process for liquefying a gas by means of a refrigeration cycle comprising a heat exchange line, a so-called expansion turbine “Hot” and a so-called “cold” expansion turbine supplied respectively at a first temperature and at a second temperature below the first temperature and at least two stages of gas compression cycle, in which the two turbines are supplied with two fractions of the gas cycle at the same inlet pressure and at least part of it is returned gas from each turbine at the suction of a compression stage, after having heated it to room temperature in the exchange line.
  • a so-called expansion turbine "Hot” and a so-called “cold” expansion turbine supplied respectively at a first temperature and at a second temperature below the first temperature and at least two stages of gas compression cycle, in which the two turbines are supplied with two fractions of the gas cycle at the same inlet pressure and at least part of it is returned gas from each turbine at the suction of a compression stage, after having heated it to room temperature in the exchange line.
  • DE-A-2 636 933 and DE-A-1 902 601 describe a process using a "hot” turbine and "cold” turbine, each coupled to a cycle compressor.
  • the outlet pressures of the two turbines are equal, as well as their inlet pressures.
  • the object of the invention is to provide a method of this type having a particularly high yield.
  • the invention relates to a process of the aforementioned type, characterized in that the cycle gas is expanded in the hot turbine up to a first exhaust pressure, and the cycle gas is relaxed in the cold turbine up to a second exhaust pressure lower than the first exhaust pressure.
  • the invention also relates to an installation for liquefying a gas intended for the implementation of the process defined above.
  • This installation of the type comprising a heat exchange line, a turbine so-called “hot” expansion, a so-called “cold” expansion turbine, means of cycle compression, comprising at least two compression stages of cycle in series, the admissions of the two turbines being connected to the discharge of the same cycle compression stage, the output of each turbine being connected to the suction of a compression stage, means for sending two fractions of a cycle gas respectively to the two turbines and means to heat at least part of the expanded gas in each turbine to room temperature before sending it to the suction of a means of compression is characterized in that the exhaust from the hot turbine is connected to the suction of a cycle compression stage, and the exhaust of the cold turbine is connected to the suction of a cycle compression stage inferior.
  • the installation comprises a main compressor 6 for atmospheric air, an apparatus 7 for purifying air in water and in anhydride carbonic adsorption, a cycle compressor 8 to two stages 9 and 10 in series, a hot turbine 11 braked by an alternator 12 and a cold turbine 13 braked by an alternator 14.
  • atmospheric air at to be treated is compressed in 6 to the medium pressure P1, which is the operating pressure of column 3 and which is typically between 5 and 6 bars absolute, then is purified in 7 and compressed again in 9 to one intermediate pressure P2 then in 10 to a high cycle pressure P3, typically of the order of 30 to 100 absolute bars.
  • a first fraction of the air at this high P3 cycle pressure is cooled down to a temperature intermediate T1 in the hot part of the line heat exchange 2, then exit therefrom and introduced into the hot turbine 11. It emerges from the latter at the inter-stage pressure P2 of the compressor 8, is warmed up to temperature ambient in the hot part of the exchange line thermal, and is returned to the second stage intake 10 of the same compressor 8.
  • the rest of the air at the high pressure of P3 cycle is cooled in 2 to a second temperature intermediate T2 lower than T1. At this temperature, part of the air has left the exchange line thermal and introduced into the cold turbine 13, whence it comes out at medium pressure P1 and at temperature the cold end of the heat exchange line. This air turbined is partly heated in 15 from the cold end to hot end of the heat exchange line and returned to the suction of the first stage 9 of the compressor 8, and for part sent to the tank in column 3.
  • the rest of the air high pressure cooled to temperature T2 continues to cool in 16 until the cold end of the heat exchange line 2, which causes its liquefaction, then is relaxed at medium pressure P1 in an expansion valve 17 and is sent to the tank of the column 3.
  • a refrigeration unit 18 to precool at least one of the two high air streams pressure from compressor 8.
  • the electrical energy produced by the two turbines in alternators 12 and 14 can be used for driving the cycle compressor 8.
  • the refrigeration cycle is used to liquefy withdrawn nitrogen at the head of the medium pressure column 3.
  • the compressor cycle 8 is a three-stage nitrogen compressor, whose first stages 9 and 10 correspond to the two stages 9 and 10 of Figure 1 and are followed by a stage additional 19 in series delivering the nitrogen to be liquefied under a high liquefaction pressure P4 greater than the highest pressure P3 in the cycle.
  • the hot turbine 11 and the cold turbine 13 are both powered by the gas from the second stage 10, and the gas from the turbine 11 is returned to the suction of this second stage 10.
  • all of the gas from of the cold turbine 13 is combined with the nitrogen withdrawn from the head of column 3 via a pipe 20, heated in 2 to room temperature and returned to the suction of the first stage 9.
  • the nitrogen from of stage 10 which is not sent to the turbines is compressed again in 19, then cooled from the hot end at the cold end of the heat exchange line, which causes its liquefaction. Then this liquid nitrogen high pressure is relaxed to medium pressure in a expansion valve 21 and introduced under reflux at the head of the column 3.

Description

La présente invention est relative à un procédé de liquéfaction d'un gaz au moyen d'un cycle frigorifique comprenant une ligne d'échange thermique, une turbine de détente dite « chaude » et une turbine de détente dite « froide » alimentées respectivement à une première température et à une seconde température inférieure à la première température et au moins deux étages de compression du gaz de cycle, dans lequel on alimente les deux turbines avec deux fractions du gaz de cycle à une même pression d'admission et on renvoie une partie au moins du gaz issu de chaque turbine à l'aspiration d'un étage de compression, après l'avoir réchauffée à la température ambiante dans la ligne d'échange.The present invention relates to a process for liquefying a gas by means of a refrigeration cycle comprising a heat exchange line, a so-called expansion turbine "Hot" and a so-called "cold" expansion turbine supplied respectively at a first temperature and at a second temperature below the first temperature and at least two stages of gas compression cycle, in which the two turbines are supplied with two fractions of the gas cycle at the same inlet pressure and at least part of it is returned gas from each turbine at the suction of a compression stage, after having heated it to room temperature in the exchange line.

Un procédé de ce type est connu de US-A-4 595 405. Dans la turbine « chaude », le gaz est détendu à une pression égale à la pression de sortie de la turbine « froide ».A process of this type is known from US-A-4,595,405. In the turbine "Hot", the gas is expanded to a pressure equal to the outlet pressure of the "cold" turbine.

DE-A-2 636 933 et DE-A-1 902 601 décrivent un procédé utilisant une turbine « chaude » et une turbine « froide », chacune couplée à un compresseur du cycle. Les pressions de sortie des deux turbines sont égales, ainsi que leurs pressions d'entrée.DE-A-2 636 933 and DE-A-1 902 601 describe a process using a "hot" turbine and "cold" turbine, each coupled to a cycle compressor. The outlet pressures of the two turbines are equal, as well as their inlet pressures.

L'invention a pour but de fournir un procédé de ce type ayant un rendement particulièrement élevé.The object of the invention is to provide a method of this type having a particularly high yield.

A cet effet, l'invention a pour objet un procédé du type précité, caractérisé en ce qu'on détend le gaz de cycle dans la turbine chaude jusqu'à une première pression d'échappement, et on détend le gaz de cycle dans la turbine froide jusqu'à une seconde pression d'échappement plus basse que la première pression d'échappement.To this end, the invention relates to a process of the aforementioned type, characterized in that the cycle gas is expanded in the hot turbine up to a first exhaust pressure, and the cycle gas is relaxed in the cold turbine up to a second exhaust pressure lower than the first exhaust pressure.

Ce procédé peut comporter un ou plusieurs des modes particuliers de réalisation de l'invention suivants :

  • une partie du gaz de cycle constitue le gaz à liquéfier et est liquéfié après avoir subi les deux étages de compression et éventuellement une compression supplémentaire;
  • le gaz à liquéfier est de l'air ou un gaz de l'air et est envoyé, après liquéfaction et détente, dans un appareil de distillation d'air;
  • la pression d'échappement de la turbine froide est une pression de fonctionnement de l'appareil de distillation, une partie au moins du gaz issu de cette turbine froide étant envoyée dans la partie correspondante de l'appareil de distillation.
This process can include one or more of the following particular embodiments of the invention:
  • part of the cycle gas constitutes the gas to be liquefied and is liquefied after having undergone the two compression stages and possibly additional compression;
  • the gas to be liquefied is air or an air gas and is sent, after liquefaction and expansion, in an air distillation apparatus;
  • the exhaust pressure of the cold turbine is an operating pressure of the distillation apparatus, at least part of the gas from this cold turbine being sent into the corresponding part of the distillation apparatus.

L'invention a également pour objet une installation de liquéfaction d'un gaz destinée à la mise en oeuvre du procédé défini ci-dessus. Cette installation, du type comprenant une ligne d'échange thermique, une turbine de détente dite « chaude », une turbine de détente dite « froide », des moyens de compression de cycle, comprenant au moins deux étages de compression de cycle en série, les admissions des deux turbines étant reliées au refoulement d'un même étage de compression de cycle, la sortie de chaque turbine étant reliée à l'aspiration d'un étage de compression, des moyens pour envoyer deux fractions d'un gaz de cycle respectivement aux deux turbines et des moyens pour réchauffer au moins une partie du gaz détendu dans chaque turbine à la température ambiante avant de l'envoyer à l'aspiration d'un moyen de compression est caractérisée en ce que l'échappement de la turbine chaude est relié à l'aspiration d'un étage de compression de cycle, et l'échappement de la turbine froide est relié à l'aspiration d'un étage de compression de cycle inférieur.The invention also relates to an installation for liquefying a gas intended for the implementation of the process defined above. This installation, of the type comprising a heat exchange line, a turbine so-called "hot" expansion, a so-called "cold" expansion turbine, means of cycle compression, comprising at least two compression stages of cycle in series, the admissions of the two turbines being connected to the discharge of the same cycle compression stage, the output of each turbine being connected to the suction of a compression stage, means for sending two fractions of a cycle gas respectively to the two turbines and means to heat at least part of the expanded gas in each turbine to room temperature before sending it to the suction of a means of compression is characterized in that the exhaust from the hot turbine is connected to the suction of a cycle compression stage, and the exhaust of the cold turbine is connected to the suction of a cycle compression stage inferior.

L'installation ainsi définie peut comporter un ou plusieurs modes particuliers de réalisation de l'invention suivants :

  • l'aspiration du premier étage de compression de cycle est également reliée au refoulement d'un compresseur principal d'air d'une installation de distillation d'air, et l'échappement de la turbine froide est relié également à une partie d'un appareil de distillation d'air de cette installation qui fonctionne sous la pression d'échappement de cette turbine froide;
  • l'aspiration du premier étage de compression de cycle est également reliée à une partie d'un appareil de distillation d'air qui fonctionne sous sa pression d'aspiration, et le refoulement du dernier étage de compression de cycle est relié éventuellement via des moyens de compression supplémentaires, à travers la ligne d'échange thermique et un organe de détente, à ladite partie de l'appareil de distillation d'air;
  • les moyens de compression de cycle sont constitués par un compresseur unique multi-étages, l'échappement de la turbine chaude au moins étant relié à une aspiration inter-étages de ce compresseur;
  • l'installation comprend en outre un groupe frigorifique de prérefroidissement d'au moins un courant de gaz à turbiner.
The installation thus defined may include one or more particular embodiments of the following invention:
  • the suction of the first cycle compression stage is also connected to the discharge of a main air compressor of an air distillation installation, and the exhaust of the cold turbine is also connected to part of a air distillation apparatus of this installation which operates under the exhaust pressure of this cold turbine;
  • the suction of the first cycle compression stage is also connected to a part of an air distillation apparatus which operates under its suction pressure, and the discharge of the last cycle compression stage is optionally connected via means additional compression, through the heat exchange line and an expansion member, to said part of the air distillation apparatus;
  • the cycle compression means are constituted by a single multi-stage compressor, the exhaust of the hot turbine at least being connected to an inter-stage suction of this compressor;
  • the installation further comprises a refrigeration unit for precooling at least one stream of gas to be turbined.

Des exemples de réalisation de l'invention vont maintenant être décrits en regard du dessin annexé, sur lequel :

  • la Figure 1 représente schématiquement une installation de liquéfaction d'air conforme à l'invention; et
  • la Figure 2 représente de façon analogue une installation de liquéfaction d'azote conforme à l'invention.
Examples of embodiments of the invention will now be described with reference to the appended drawing, in which:
  • Figure 1 schematically shows an air liquefaction installation according to the invention; and
  • Figure 2 similarly shows a nitrogen liquefaction installation according to the invention.

Dans chacune des Figures 1 et 2, on a illustré l'application de l'invention à une installation de distillation d'air comprenant une double colonne de distillation d'air 1 et une ligne d'échange thermique 2 du type à échange de chaleur indirect et à contre-courant. La double colonne 1 comprend elle-même une colonne moyenne pression 3 surmontée d'une colonne basse pression 4 et couplée à celle-ci par un vaporisateur-condenseur 5. Toutefois, on n'a représenté aux Figures 1 et 2 que les parties de l'installation de distillation d'air concernées par la présente invention, et en particulier le cycle de liquéfaction, mais on comprend que l'installation comporte également toutes les conduites et tous les équipements habituels nécessaires pour la production de gaz de l'air par distillation. Dans le cas de la Figure 1, le gaz liquéfié est de l'air à traiter, tandis que dans le cas de la Figure 2, le gaz liquéfié est de l'azote.In each of Figures 1 and 2, we have illustrated the application of the invention to an installation air distillation system comprising a double column of air distillation 1 and a heat exchange line 2 of the indirect heat exchange and counter-current type. The double column 1 itself includes a medium pressure column 3 surmounted by a low column pressure 4 and coupled to it by a vaporizer-condenser 5. However, we have only shown in Figures 1 and 2 as the parts of the distillation plant air concerned by the present invention, and especially the liquefaction cycle, but we understand that the installation also includes all the pipes and all the usual equipment necessary for the production of air gases by distillation. In the case of Figure 1, the liquefied gas is air at treat, while in the case of Figure 2, the gas liquefied is nitrogen.

Dans l'exemple de la Figure 1, l'installation comprend un compresseur principal 6 d'air atmosphérique, un appareil 7 d'épuration d'air en eau et en anhydride carbonique par adsorption, un compresseur de cycle 8 à deux étages 9 et 10 en série, une turbine chaude 11 freinée par un alternateur 12, et une turbine froide 13 freinée par un alternateur 14.In the example in Figure 1, the installation comprises a main compressor 6 for atmospheric air, an apparatus 7 for purifying air in water and in anhydride carbonic adsorption, a cycle compressor 8 to two stages 9 and 10 in series, a hot turbine 11 braked by an alternator 12 and a cold turbine 13 braked by an alternator 14.

En fonctionnement, l'air atmosphérique à traiter est comprimé en 6 jusqu'à la moyenne pression P1, qui est la pression de fonctionnement de la colonne 3 et qui est typiquement comprise entre 5 et 6 bars absolus, puis est épuré en 7 et comprimé de nouveau en 9 à une pression intermédiaire P2 puis en 10 jusqu'à une haute pression de cycle P3, typiquement de l'ordre de 30 à 100 bars absolus.In operation, atmospheric air at to be treated is compressed in 6 to the medium pressure P1, which is the operating pressure of column 3 and which is typically between 5 and 6 bars absolute, then is purified in 7 and compressed again in 9 to one intermediate pressure P2 then in 10 to a high cycle pressure P3, typically of the order of 30 to 100 absolute bars.

Une première fraction de l'air à cette haute pression de cycle P3 est refroidie jusqu'à une température intermédiaire T1 dans la partie chaude de la ligne d'échange thermique 2, puis sortie de celle-ci et introduite dans la turbine chaude 11. Elle ressort de cette dernière à la pression d'inter-étages P2 du compresseur 8, est réchauffée jusqu'à la température ambiante dans la partie chaude de la ligne d'échange thermique, et est renvoyée à l'admission du second étage 10 du même compresseur 8.A first fraction of the air at this high P3 cycle pressure is cooled down to a temperature intermediate T1 in the hot part of the line heat exchange 2, then exit therefrom and introduced into the hot turbine 11. It emerges from the latter at the inter-stage pressure P2 of the compressor 8, is warmed up to temperature ambient in the hot part of the exchange line thermal, and is returned to the second stage intake 10 of the same compressor 8.

Le reste de l'air à la haute pression de cycle P3 est refroidi en 2 jusqu'à une seconde température intermédiaire T2 inférieure à T1. A cette température, une partie de l'air est sortie de la ligne d'échange thermique et introduite dans la turbine froide 13, d'où elle ressort à la moyenne pression P1 et à la température du bout froid de la ligne d'échange thermique. Cet air turbiné est pour partie réchauffé en 15 du bout froid au bout chaud de la ligne d'échange thermique et renvoyé à l'aspiration du premier étage 9 du compresseur 8, et pour partie envoyé en cuve de la colonne 3. Le reste de l'air haute pression refroidi jusqu'à la température T2 poursuit son refroidissement en 16 jusqu'au bout froid de la ligne d'échange thermique 2, ce qui provoque sa liquéfaction, puis est détendu à la moyenne pression P1 dans une vanne de détente 17 et est envoyé en cuve de la colonne 3.The rest of the air at the high pressure of P3 cycle is cooled in 2 to a second temperature intermediate T2 lower than T1. At this temperature, part of the air has left the exchange line thermal and introduced into the cold turbine 13, whence it comes out at medium pressure P1 and at temperature the cold end of the heat exchange line. This air turbined is partly heated in 15 from the cold end to hot end of the heat exchange line and returned to the suction of the first stage 9 of the compressor 8, and for part sent to the tank in column 3. The rest of the air high pressure cooled to temperature T2 continues to cool in 16 until the cold end of the heat exchange line 2, which causes its liquefaction, then is relaxed at medium pressure P1 in an expansion valve 17 and is sent to the tank of the column 3.

Comme représenté en traits interrompus sur la Figure 1, on peut utiliser un groupe frigorifique 18 pour prérefroidir l'un au moins des deux courants d'air haute pression issus du compresseur 8.As shown in dashed lines on the Figure 1, we can use a refrigeration unit 18 to precool at least one of the two high air streams pressure from compressor 8.

L'énergie électrique produite par les deux turbines dans les alternateurs 12 et 14 peut être utilisée pour l'entraínement du compresseur de cycle 8.The electrical energy produced by the two turbines in alternators 12 and 14 can be used for driving the cycle compressor 8.

Dans le mode de réalisation de la Figure 2, le cycle frigorifique sert à liquéfier de l'azote soutiré en tête de la colonne moyenne pression 3. Le compresseur de cycle 8 est un compresseur d'azote à trois étages, dont les premiers étages 9 et 10 correspondent aux deux étages 9 et 10 de la Figure 1 et sont suivis d'un étage supplémentaire 19 en série délivrant l'azote à liquéfier sous une haute pression de liquéfaction P4 supérieure à la plus haute pression P3 du cycle.In the embodiment of Figure 2, the refrigeration cycle is used to liquefy withdrawn nitrogen at the head of the medium pressure column 3. The compressor cycle 8 is a three-stage nitrogen compressor, whose first stages 9 and 10 correspond to the two stages 9 and 10 of Figure 1 and are followed by a stage additional 19 in series delivering the nitrogen to be liquefied under a high liquefaction pressure P4 greater than the highest pressure P3 in the cycle.

Comme précédemment, la turbine chaude 11 et la turbine froide 13 sont toutes deux alimentées par le gaz issu du deuxième étage 10, et le gaz issu de la turbine 11 est renvoyé à l'aspiration de ce deuxième étage 10. Toutefois, dans ce cas, la totalité du gaz issu de la turbine froide 13 est réuni à l'azote soutiré de la tête de la colonne 3 via une conduite 20, réchauffé en 2 jusqu'à la température ambiante et renvoyé à l'aspiration du premier étage 9. De plus, l'azote issu de l'étage 10 qui n'est pas envoyé aux turbines est comprimé de nouveau en 19, puis refroidi du bout chaud au bout froid de la ligne d'échange thermique, ce qui provoque sa liquéfaction. Ensuite, cet azote liquide haute pression est détendu à la moyenne pression dans une vanne de détente 21 et introduit en reflux en tête de la colonne 3.As before, the hot turbine 11 and the cold turbine 13 are both powered by the gas from the second stage 10, and the gas from the turbine 11 is returned to the suction of this second stage 10. However, in this case, all of the gas from of the cold turbine 13 is combined with the nitrogen withdrawn from the head of column 3 via a pipe 20, heated in 2 to room temperature and returned to the suction of the first stage 9. In addition, the nitrogen from of stage 10 which is not sent to the turbines is compressed again in 19, then cooled from the hot end at the cold end of the heat exchange line, which causes its liquefaction. Then this liquid nitrogen high pressure is relaxed to medium pressure in a expansion valve 21 and introduced under reflux at the head of the column 3.

Dans chacun des modes de réalisation ci-dessus, l'alimentation des deux turbines à des températures décalées Tl et T2 mais à la même pression, et leur échappement à deux pressions différentes P1 et P2, dont une pression plus basse pour la turbine froide, conduisent à un rendement élevé du cycle de liquéfaction. De plus, l'utilisation d'un compresseur de cycle multi-étages 8 apporte une simplification de l'installation et un avantage substantiel du point de vue de l'investissement.In each of the above embodiments, supply of the two turbines at temperatures offset Tl and T2 but at the same pressure, and their exhaust at two different pressures P1 and P2, of which lower pressure for the cold turbine, drive high efficiency of the liquefaction cycle. Of plus, the use of a multi-stage cycle compressor 8 provides a simplification of the installation and a substantial advantage from an investment standpoint.

Claims (9)

  1. Process for liquefying a gas by means of a cooling cycle comprising a heat exchange line (2), a so-called "warm" expansion turbine (11) and a so-called "cold" expansion turbine (13) supplied respectively at a first temperature (T1) and at a second temperature (T2) lower than the first temperature, and at least two stages (9,10) for compressing the cycle gas, wherein the two turbines (11,13) are supplied with two cycle gas fractions at the same intake pressure (P3) and at least part of the gas emerging from each turbine (11,13) is conveyed to the induction inlet of a compression stage (10,9) after having been reheated to ambient temperature in the exchange line, characterized in that the cycle gas is expanded in the warm turbine (11) to a first exhaust pressure (P2) and the cycle gas is expanded in the cold turbine (13) to a second exhaust pressure (P1) lower than the first exhaust pressure (P2).
  2. Process according to claim 1, characterized in that part of the cycle gas constitutes the gas to be liquefied and is liquefied after having undergone the two compression stages and possibly a supplementary compression stage (in 19).
  3. Process according to claim 1 or claim 2, characterized in that the gas to be liquefied is air or a gas from the air and is conveyed, after liquefaction and expansion (in 17;21) to an air distillation unit (1).
  4. Process according to claims 2 and 3 together, characterized in that the exhaust pressure from the cold turbine (13) is an operating pressure of the distillation unit (1), at least part of the gas emerging from this cold turbine being conveyed to the corresponding part (3) of the distillation unit.
  5. Plant for liquefying a gas, of the type comprising a heat exchange line (2), a so-called "warm" expansion turbine (11), a so-called "cold" expansion turbine (12), means for cycle compression, comprising at least two compression stages (9,10) in series, the intakes of the two turbines (11,13) being connected to the delivery outlet from the same cycle compression stage (10), the outlet from each turbine being connected to the induction inlet of a compression stage, means for conveying two fractions of a cycle gas respectively to the two turbines and means (2) for reheating at least part of the gas expanded in each turbine to ambient temperature before conveying it to the induction inlet of a means of compression, characterized in that the exhaust from the warm turbine (11) is connected to the induction inlet of a cycle compression stage (10), and the exhaust from the cold turbine (13) is connected to the induction inlet of a lower cycle compression stage (9)
  6. Plant according to claim 5, characterized in that the induction inlet of the first cycle compression stage (9) is also connected to the delivery outlet from a main air compressor (6) of an air distillation plant, and the exhaust from the cold turbine (13) is also connected to a part (3) of an air distillation unit (1) of this plant which operates at the exhaust pressure of this cold turbine.
  7. Plant according to claim 5, characterized in that the induction inlet of the first cycle compression stage (9) is also connected to a part (3) of an air distillation unit (1) which operates at its induction pressure, and the delivery outlet from the last cycle compression stage (10) is connected, possibly via supplementary means of compression (19), through the heat exchange line (2) and an expansion device (21), to the said part (3) of the air distillation unit.
  8. Plant according to any one of claims 5 to 7, characterized in that the cycle compression means (9,10) consist of a single multi-stage compressor, the exhaust of at least the warm turbine (11) being connected to an interstage induction inlet of this compressor.
  9. Plant according to any one of claims 5 to 8, characterized in that it additionally includes a cooling unit (18) for precooling at least one gas flow to be turbined.
EP94402787A 1993-12-31 1994-12-05 Process and installation for the liquefaction of a gas Expired - Lifetime EP0661505B1 (en)

Applications Claiming Priority (2)

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FR9315959A FR2714721B1 (en) 1993-12-31 1993-12-31 Method and installation for liquefying a gas.
FR9315959 1993-12-31

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EP0661505B1 true EP0661505B1 (en) 1998-05-27

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EP (1) EP0661505B1 (en)
JP (1) JPH07324857A (en)
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US5758515A (en) * 1997-05-08 1998-06-02 Praxair Technology, Inc. Cryogenic air separation with warm turbine recycle
FR2765889B1 (en) * 1997-07-08 1999-08-13 Air Liquide METHOD AND INSTALLATION FOR SUPPLYING A BLAST FURNACE
US5983666A (en) * 1997-10-27 1999-11-16 The Boc Group, Inc. Air separation plant and method of fabrication
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DE19843629A1 (en) * 1998-09-23 2000-03-30 Linde Ag Process and liquefier for the production of liquid air
FR2787560B1 (en) * 1998-12-22 2001-02-09 Air Liquide PROCESS FOR CRYOGENIC SEPARATION OF AIR GASES
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JP5643491B2 (en) * 2009-07-24 2014-12-17 大陽日酸株式会社 Air liquefaction separation method and apparatus
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US5454226A (en) 1995-10-03
JPH07324857A (en) 1995-12-12
FR2714721A1 (en) 1995-07-07
FR2714721B1 (en) 1996-02-16
EP0661505A1 (en) 1995-07-05
ES2119115T3 (en) 1998-10-01
CA2139304A1 (en) 1995-07-01
CN1107571A (en) 1995-08-30
DE69410584D1 (en) 1998-07-02
DE69410584T2 (en) 1999-03-04

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