EP0694746A1 - Process for the production of a gas under pressure in variable quantities - Google Patents

Process for the production of a gas under pressure in variable quantities Download PDF

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Publication number
EP0694746A1
EP0694746A1 EP95401774A EP95401774A EP0694746A1 EP 0694746 A1 EP0694746 A1 EP 0694746A1 EP 95401774 A EP95401774 A EP 95401774A EP 95401774 A EP95401774 A EP 95401774A EP 0694746 A1 EP0694746 A1 EP 0694746A1
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EP
European Patent Office
Prior art keywords
air
liquid
pressure
heat exchange
container
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EP95401774A
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German (de)
French (fr)
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EP0694746B1 (en
Inventor
Maurice Grenier
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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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Classifications

    • 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
    • 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
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • 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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04163—Hot end purification of the feed air
    • F25J3/04169—Hot end purification of the feed air by adsorption of the impurities
    • F25J3/04175—Hot end purification of the feed air by adsorption of the impurities at a pressure of substantially more than the highest 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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/04236—Integration of different exchangers in a single core, so-called integrated cores
    • 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
    • F25J3/04406—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
    • 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
    • F25J3/04472—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages
    • F25J3/04496—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages for compensating variable air feed or variable product demand by alternating between periods of liquid storage and liquid assist
    • F25J3/04503—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages for compensating variable air feed or variable product demand by alternating between periods of liquid storage and liquid assist by exchanging "cold" between at least two different cryogenic liquids, e.g. independently from the main heat exchange line of the air fractionation and/or by using external alternating storage systems
    • F25J3/04509—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages for compensating variable air feed or variable product demand by alternating between periods of liquid storage and liquid assist by exchanging "cold" between at least two different cryogenic liquids, e.g. independently from the main heat exchange line of the air fractionation and/or by using external alternating storage systems within the cold part of the air fractionation, i.e. exchanging "cold" within the fractionation and/or main heat exchange line
    • 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
    • Y10S62/912—External refrigeration system
    • Y10S62/913—Liquified gas

Definitions

  • the pressures indicated are absolute pressures.
  • the expression “condensation” and “vaporization” means either a condensation or a vaporization proper, or a pseudo-condensation or a pseudo-vaporization, depending on whether the pressures are sub-critical or super-critical.
  • the object of the invention is to provide means making it possible to satisfy a variable demand for oxygen under pressure in a particularly simple manner and without appreciable degradation in performance, nor in thermal terms, that is to say the equilibrium of the heat exchange line, or on that of air distillation.
  • the subject of the invention is a method of the aforementioned type, characterized in that the liquid drawn off is stored under a pressure close to atmospheric pressure while the liquid air is stored under a storage pressure at least equal to, and preferably significantly higher than, the highest operating pressure of the distillation apparatus.
  • the invention also relates to an installation for producing a pressurized gas with variable flow rate, intended for the implementation of the process defined above.
  • This installation of the type comprising an air distillation apparatus, a heat exchange line for cooling the air by heat exchange with products coming from the distillation apparatus, compression means suitable for bringing at least a fraction of the air to be distilled to a high pressure, and sending it into air liquefaction passages of the heat exchange line, a liquid storage container connected to the distillation apparatus and provided with means for withdrawing liquid with adjustable flow rate, bringing it to the vaporization pressure and sending it into vaporization passages of the heat exchange line, and an air storage container liquid connected upstream to the air liquefaction passages of the heat exchange line and, downstream, and via expansion means with adjustable flow rate, to the distillation apparatus, is characterized in that the container of the withdrawn liquid is under a pressure close to atmospheric pressure, while the liquid air storage container is under a pressure significantly higher than the highest operating pressure of the distillation apparatus.
  • the air distillation installation shown in FIG. 1 essentially comprises: an air compressor 1, an apparatus 2 for purifying the compressed air in water and in CO2 by adsorption, this apparatus comprising two adsorption bottles 2A, 2B, one of which operates in adsorption while the other is in the process of regeneration, a blower turbine assembly 3 comprising an expansion turbine 4 and a blower or blower 5 whose shafts are coupled, the blower being optionally equipped with '' a refrigerant (not shown), a heat exchanger 6 constituting the heat exchange line of the installation, a double distillation column 7 comprising a medium column pressure 8 surmounted by a low pressure column 9, with a vaporizer-condenser 10 putting the overhead vapor (nitrogen) from column 8 in heat exchange relation with the tank liquid (oxygen) from column 9, and a liquid oxygen tank 11, the bottom of which is connected to a liquid oxygen pump 12 and a liquid air tank 13.
  • This installation is mainly intended to supply, via a pipe 15, gaseous oxygen under a predetermined high pressure, which can be between approximately 13 ⁇ 105 Pa and a few megaPascals.
  • liquid oxygen withdrawn from the tank of the column 9 via a pipe 16 equipped with a valve 17 for regulating the level of liquid in the tank of the column 9, is stored in the tank 11. From the liquid oxygen withdrawn from this tank is brought to the high vaporization pressure by the pump 12 in the liquid state, then vaporized and heated under this high pressure in passages 18 of the exchange line 6.
  • All of the air to be distilled is compressed by compressor 1 at a pressure higher than the medium pressure of column 8 but lower than the high pressure. Then the air, precooled near ambient temperature in 19 and cooled to a temperature between + 5 ° C and + 25 ° C in 20, is purified in one, 2A for example, adsorption bottles, and fully boosted at high pressure by the booster 5, which is driven by the turbine 4.
  • the air is then introduced at the hot end of the exchanger 6 and completely cooled to an intermediate temperature. At this temperature, a fraction of the air continues to cool and is liquefied in passages 21 of the exchanger, then leaves the exchange line and is sent to the reservoir 13 via a pipe 22.
  • Liquid air withdrawn from this reservoir 13 via a pipe 24 is sub-cooled in the cold part of the exchange line 6, then is expanded at low pressure in an expansion valve 25 with adjustable opening and introduced to a intermediate level in column 9.
  • part liquid air can be expanded at medium pressure and introduced into column 8.
  • the low-pressure nitrogen is heated in passages 32 of the exchanger 6 and then discharged via a line 33, while the waste gas W, after heating in passages 34 of the exchanger, is used to regenerate an adsorption bottle , the bottle 2B in the example considered, before being evacuated via a pipe 35.
  • FIG. 1 also shows a pipe 36 for discharging liquid oxygen from the installation stitched on the discharge pipe of the pump 12.
  • the high air pressure, at the discharge of the blower, is between approximately 25 x 105 Pa and the condensation pressure of the air by vaporization of oxygen under the high oxygen pressure.
  • the refrigeration balance of the installation is balanced, with a temperature difference at the hot end of the heat exchange line of the order of 3 ° C. , by withdrawing from the installation at least one product, here oxygen, in liquid form, via line 36.
  • the liquid level in the reservoir 13 is constant, as is that of the reservoir 11.
  • the opening of the valve 25 is increased in order to increase the quantity of liquid in the column 9.
  • the valve 17 opens, so an increased flow of liquid oxygen is sent to the tank 11.
  • the liquid air contained in the reservoir 13 being at high pressure, its latent heat of liquefaction is low, so that the additional flow of liquid air sent to the column 9 is substantially greater than the additional flow of oxygen than we draw from it.
  • the greater the pressure of the liquid air the greater it is.
  • the quantity of cold gases produced by the double column and sent into the heat exchange line increases, compensating all the more for the reduction in the quantity of cold sent to the latter due to the decrease in the demand for gaseous oxygen. and, consequently, of the flow of oxygen vaporized in the passages 18, this reduction being obtained by reducing the speed of the pump 12.
  • this air is taken at the outlet of the device 2 via a pipe 38, cooled and liquefied in additional passages 21A of the exchange line, and sent as previously to the container 13 via the pipe 22.
  • the liquefaction passages 21 of the air under high pressure are equipped, at the cold end of the exchange line, with an expansion valve 25A, and the sub-cooling passages of the liquid air withdrawn from the container 13 are equipped, at the same cold end, with the expansion valve 25.
  • valves 25 and 25A which ensures the operation of the air / oxygen rocker, similar moreover to what has been described above with reference to FIG. 1.
  • the optimum pressure range from the point of view of the thermal equilibrium of the exchange line 6 and that of the distillation conditions, is between approximately 30 ⁇ 105 Pa and approximately 35 ⁇ 105 Pa.
  • the invention also applies to the case where the liquid withdrawn is nitrogen, argon or another liquid.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

A process and installation are claimed for the production of a gas under pressure, at a variable flow rate, particularly for the distillation of air to produce oxygen and nitrogen streams. Air is distilled in a distillation column (7) after cooling by heat exchange (6) with distillation products. Liquid oxygen is withdrawn from the column (16 and 17) and stored (11) at near atmospheric pressure, then used at a variable rate (12). Liquified air is stored (13) at a pressure higher than that in the distillation column before use. It is fed to the column as needed via a pressure reducing valve (25). <IMAGE>

Description

La présente invention est relative d'un gaz sous pression à débit variable, du type l'air dans une installation de distillation d'air comprenant un appareil de distillation et une ligne d'échange thermique pour refroidir l'air par échange de chaleur avec des produits provenant de l'appareil de distillation ; on soutire un liquide de cet appareil, on l'amène à une pression de vaporisation, on le vaporise et on le réchauffe sous cette pression dans la ligne d'échange thermique pour former le gaz sous pression, cette vaporisation et ce réchauffement s'accompagnant d'une liquéfaction d'air dans ses passages de liquéfaction d'air de la ligne d'échange thermique ; et dans lequel :

  • lors d'une réduction de la demande du gaz sous pression par rapport au débit nominal, on soutire de l'appareil de distillation, sous forme liquide, l'excédent produit par cet appareil, on envoie ce liquide dans un récipient de stockage de liquide, et on introduit dans l'appareil de distillation une quantité additionnelle correspondante d'air liquide préalablement stocké ; et
  • lors d'une augmentation de la demande d'oxygène gazeux sous pression par rapport au débit nominal, on soutire l'excès demandé, sous forme liquide, du récipient de stockage de liquide, on l'amène à la pression de vaporisation, et on le vaporise sous cette pression dans la ligne d'échange thermique, et on stocke une quantité correspondante d'air liquéfié par ladite liquéfaction dans le récipient de stockage d'air liquide.
The present invention relates to a pressurized gas with variable flow rate, of the air type in an air distillation installation comprising a distillation apparatus and a heat exchange line for cooling the air by heat exchange with products from the distillation apparatus; a liquid is drawn from this device, it is brought to a vaporization pressure, it is vaporized and it is heated under this pressure in the heat exchange line to form the gas under pressure, this vaporization and this heating being accompanied air liquefaction in its air liquefaction passages of the heat exchange line; and in which:
  • when the demand for pressurized gas is reduced compared to the nominal flow rate, the excess produced by this apparatus is withdrawn from the distillation apparatus in liquid form, this liquid is sent to a liquid storage container , and a corresponding additional quantity of previously stored liquid air is introduced into the distillation apparatus; and
  • during an increase in the demand for gaseous oxygen under pressure relative to the nominal flow rate, the required excess is withdrawn, in liquid form, from the liquid storage container, it is brought to the vaporization pressure, and vaporizes it under this pressure in the heat exchange line, and stores a corresponding amount of air liquefied by said liquefaction in the liquid air storage container.

Dans le présent mémoire, les pressions indiquées sont des pressions absolues. De plus, on entend par "condensation" et "vaporisation" soit une condensation ou une vaporisation proprement dite, soit une pseudo-condensation ou une pseudo-vaporisation, selon que les pressions sont sub-critiques ou super-critiques.In this specification, the pressures indicated are absolute pressures. In addition, the expression "condensation" and "vaporization" means either a condensation or a vaporization proper, or a pseudo-condensation or a pseudo-vaporization, depending on whether the pressures are sub-critical or super-critical.

Les procédés de ce type (voir par exemple le brevet français FR-A-1.158.639) sont parfois appelés "procédés à pompe et à bascule air-oxygène ou air-azote". L'invention s'applique particulièrement aux procédés dits "à paliers décalés", dont les exemples sont décrits dans les demandes de brevet français FR-A-2.674.011 ; FR-A-2.688.052 et FR-A-2.692.664 et 93.04274. Ces procédés, dans lesquels la liquéfaction de l'air s'effectue à une température inférieure à la température de vaporisation de l'oxygène sous sa pression de vaporisation, présentent des avantages intéressants tant du point de vue de la consommation en énergie spécifique, c'est-à-dire de l'énergie nécessaire pour produire une quantité donnée d'oxygène gazeux sous pression.Processes of this type (see for example French patent FR-A-1,158,639) are sometimes called "pump and air-oxygen or air-nitrogen rocker processes". The invention applies particularly to so-called "offset bearing" methods, the examples of which are described in French patent applications FR-A-2,674,011; FR-A-2.688.052 and FR-A-2.692.664 and 93.04274. These processes, in which air liquefaction takes place a temperature below the vaporization temperature of the oxygen under its vaporization pressure, have advantageous advantages both from the point of view of the consumption of specific energy, that is to say of the energy necessary to produce a quantity given oxygen gas under pressure.

L'invention a pour but de fournir des moyens permettant de satisfaire à une demande variable en oxygène sous pression de façon particulièrement simple et sans dégradation sensible des performances, ni sur le plan thermique, c'est-à-dire de l'équilibre de la ligne d'échange thermique, ni sur celui de la distillation de l'air.The object of the invention is to provide means making it possible to satisfy a variable demand for oxygen under pressure in a particularly simple manner and without appreciable degradation in performance, nor in thermal terms, that is to say the equilibrium of the heat exchange line, or on that of air distillation.

A cet effet, l'invention a pour objet un procédé du type précité, caractérisé en ce que l'on stocke le liquide soutiré sous une pression voisine de la pression atmosphérique tandis que l'on stocke l'air liquide sous une pression de stockage au moins égale, et de préférence nettement supérieure, à la plus forte pression de fonctionnement de l'appareil de distillation.To this end, the subject of the invention is a method of the aforementioned type, characterized in that the liquid drawn off is stored under a pressure close to atmospheric pressure while the liquid air is stored under a storage pressure at least equal to, and preferably significantly higher than, the highest operating pressure of the distillation apparatus.

Ce procédé peut comporter une ou plusieurs des caractéristiques suivantes :

  • le palier de stockage d'air liquide est à une pression voisine de la pression à laquelle s'effectue ladite liquéfaction d'air ;
  • le récipient de stockage d'air liquide est à une pression comprise entre 30 x 10⁵ Pa et 35 x 10⁵ Pa environ ;
  • la totalité du liquide vaporisé est soutirée du récipient de stockage de liquide ;
  • on effectue ladite liquéfaction d'air à une température inférieure à la température de vaporisation du liquide sous ladite pression de vaporisation, et on évacue au moins un produit liquide de l'installation ; et
  • on comprime l'air destiné au récipient de stockage d'air liquide à ladite pression de stockage et le reste de l'air à une haute pression supérieure à cette pression de stockage.
This process can include one or more of the following characteristics:
  • the liquid air storage level is at a pressure close to the pressure at which said air liquefaction takes place;
  • the liquid air storage container is at a pressure between approximately 30 x 10⁵ Pa and 35 x 10⁵ Pa;
  • all of the vaporized liquid is withdrawn from the liquid storage container;
  • said air liquefaction is carried out at a temperature below the vaporization temperature of the liquid under said vaporization pressure, and at least one liquid product is removed from the installation; and
  • the air intended for the liquid air storage container is compressed to said storage pressure and the rest of the air to a high pressure greater than this storage pressure.

L'invention a également pour objet une installation de production d'un gaz sous pression à débit variable, destinée à la mise en oeuvre du procédé défini ci-dessus. Cette installation du type comprenant un appareil de distillation d'air, une ligne d'échange thermique pour refroidir l'air par échange de chaleur avec des produits provenant de l'appareil de distillation, des moyens de compression adaptés pour amener au moins une fraction de l'air à distiller à une haute pression, et l'envoyer dans des passages de liquéfaction d'air de la ligne d'échange thermique, un récipient de stockage de liquide relié à l'appareil de distillation et muni de moyens pour soutirer du liquide à débit réglable, l'amener à la pression de vaporisation et l'envoyer dans des passages de vaporisation de la ligne d'échange thermique, et un récipient de stockage d'air liquide relié en amont aux passages de liquéfaction d'air de la ligne d'échange thermique et, en aval, et via des moyens de détente à débit réglable, à l'appareil de distillation, est caractérisée en ce que le récipient du liquide soutiré se trouve sous une pression voisine de la pression atmosphérique, tandis que le récipient de stockage d'air liquide se trouve sous une pression nettement supérieure à la plus forte pression de fonctionnement de l'appareil de distillation.The invention also relates to an installation for producing a pressurized gas with variable flow rate, intended for the implementation of the process defined above. This installation of the type comprising an air distillation apparatus, a heat exchange line for cooling the air by heat exchange with products coming from the distillation apparatus, compression means suitable for bringing at least a fraction of the air to be distilled to a high pressure, and sending it into air liquefaction passages of the heat exchange line, a liquid storage container connected to the distillation apparatus and provided with means for withdrawing liquid with adjustable flow rate, bringing it to the vaporization pressure and sending it into vaporization passages of the heat exchange line, and an air storage container liquid connected upstream to the air liquefaction passages of the heat exchange line and, downstream, and via expansion means with adjustable flow rate, to the distillation apparatus, is characterized in that the container of the withdrawn liquid is under a pressure close to atmospheric pressure, while the liquid air storage container is under a pressure significantly higher than the highest operating pressure of the distillation apparatus.

Suivant d'autres caractéristiques de l'installation :

  • le récipient de stockage d'air liquide est relié auxdits passages de liquéfaction d'air par l'intermédiaire d'une vanne de détente ;
  • les moyens de compression comprennent un compresseur d'air principal suivi d'une soufflante adaptée pour surpresser une fraction de l'air non destinée au récipient de stockage d'air liquide.
According to other characteristics of the installation:
  • the liquid air storage container is connected to said air liquefaction passages by means of an expansion valve;
  • the compression means comprise a main air compressor followed by a blower adapted to overpress a fraction of the air not intended for the liquid air storage container.

Des exemples de mise en oeuvre de l'invention vont maintenant être décrits en regard des dessins annexés sur lesquels :

  • la figure 1 représente schématiquement une installation de production d'oxygène gazeux sous pression à débit variable conforme à l'invention ; et
  • la figure 2 est une vue analogue d'une variante.
Examples of implementation of the invention will now be described with reference to the accompanying drawings in which:
  • FIG. 1 schematically represents an installation for producing gaseous oxygen under pressure with variable flow rate according to the invention; and
  • Figure 2 is a similar view of a variant.

L'installation de distillation d'air représentée à la figure 1 comprend essentiellement : un compresseur d'air 1, un appareil 2 d'épuration de l'air comprimé en eau et en CO₂ par adsorption, cet appareil comprenant deux bouteilles d'adsorption 2A, 2B dont l'une fonctionne en adsorption pendant que l'autre est en cours de régénération, un ensemble turbine soufflante 3 comprenant une turbine de détente 4 et une soufflante ou surpresseur 5 dont les arbres sont couplés, la soufflante étant éventuellement équipée d'un réfrigérant (non représenté), un échangeur de chaleur 6 constituant la ligne d'échange thermique de l'installation, une double colonne de distillation 7 comprenant une colonne moyenne pression 8 surmontée d'une colonne basse pression 9, avec un vaporiseur-condenseur 10 mettant la vapeur de tête (azote) de la colonne 8 en relation d'échange thermique avec le liquide de cuve (oxygène) de la colonne 9, et un réservoir d'oxygène liquide 11 dont le fond est relié à une pompe d'oxygène liquide 12 et un réservoir d'air liquide 13.The air distillation installation shown in FIG. 1 essentially comprises: an air compressor 1, an apparatus 2 for purifying the compressed air in water and in CO₂ by adsorption, this apparatus comprising two adsorption bottles 2A, 2B, one of which operates in adsorption while the other is in the process of regeneration, a blower turbine assembly 3 comprising an expansion turbine 4 and a blower or blower 5 whose shafts are coupled, the blower being optionally equipped with '' a refrigerant (not shown), a heat exchanger 6 constituting the heat exchange line of the installation, a double distillation column 7 comprising a medium column pressure 8 surmounted by a low pressure column 9, with a vaporizer-condenser 10 putting the overhead vapor (nitrogen) from column 8 in heat exchange relation with the tank liquid (oxygen) from column 9, and a liquid oxygen tank 11, the bottom of which is connected to a liquid oxygen pump 12 and a liquid air tank 13.

Cette installation est principalement destinée à fournir, via une conduite 15, de l'oxygène gazeux sous une haute pression prédéterminée, qui peut être comprise entre environ 13 x 10⁵ Pa et quelques mégaPascal.This installation is mainly intended to supply, via a pipe 15, gaseous oxygen under a predetermined high pressure, which can be between approximately 13 × 10⁵ Pa and a few megaPascals.

Pour cela, de l'oxygène liquide, soutiré de la cuve de la colonne 9 via une conduite 16 équipée d'une vanne 17 de régulation du niveau de liquide dans la cuve de la colonne 9, est stocké dans le réservoir 11. De l'oxygène liquide soutiré de ce réservoir est amené à la haute pression de vaporisation par la pompe 12 à l'état liquide, puis vaporisé et réchauffé sous cette haute pression dans des passages 18 de la ligne d'échange 6.For this, liquid oxygen, withdrawn from the tank of the column 9 via a pipe 16 equipped with a valve 17 for regulating the level of liquid in the tank of the column 9, is stored in the tank 11. From the liquid oxygen withdrawn from this tank is brought to the high vaporization pressure by the pump 12 in the liquid state, then vaporized and heated under this high pressure in passages 18 of the exchange line 6.

La chaleur nécessaire à cette vaporisation et à ce réchauffage, ainsi qu'au réchauffage et éventuellement à la vaporisation d'autres fluides soutirés de la double colonne, est fournie par l'air à distiller, dans les conditions suivantes :The heat necessary for this vaporization and this reheating, as well as for the reheating and possibly for the vaporization of other fluids drawn from the double column, is supplied by the air to be distilled, under the following conditions:

La totalité de l'air à distiller est comprimée par le compresseur 1 à une pression supérieure à la moyenne pression de la colonne 8 mais inférieure à la haute pression. Puis l'air, prérefroidi au voisinage de la température ambiante en 19 et refroidi à une température comprise entre +5°C et +25°C en 20, est épuré dans l'une, 2A par exemple, des bouteilles d'adsorption, et surpressé en totalité à la haute pression par le surpresseur 5, lequel est entraîné par la turbine 4.All of the air to be distilled is compressed by compressor 1 at a pressure higher than the medium pressure of column 8 but lower than the high pressure. Then the air, precooled near ambient temperature in 19 and cooled to a temperature between + 5 ° C and + 25 ° C in 20, is purified in one, 2A for example, adsorption bottles, and fully boosted at high pressure by the booster 5, which is driven by the turbine 4.

L'air est alors introduit au bout chaud de l'échangeur 6 et refroidi en totalité jusqu'à une température intermédiaire. A cette température, une fraction de l'air poursuit son refroidissement et est liquéfiée dans des passages 21 de l'échangeur, puis est sortie de la ligne d'échange et envoyée dans le réservoir 13 via une conduite 22.The air is then introduced at the hot end of the exchanger 6 and completely cooled to an intermediate temperature. At this temperature, a fraction of the air continues to cool and is liquefied in passages 21 of the exchanger, then leaves the exchange line and is sent to the reservoir 13 via a pipe 22.

De l'air liquide soutiré de ce réservoir 13 via une conduite 24 est sous-refroidi dans la partie froide de la ligne d'échange 6, puis est détendu à la basse pression dans une vanne de détente 25 à ouverture réglable et introduit à un niveau intermédiaire dans la colonne 9. En variante, une partie de l'air liquide peut être détendue à la moyenne pression et introduite dans la colonne 8.Liquid air withdrawn from this reservoir 13 via a pipe 24 is sub-cooled in the cold part of the exchange line 6, then is expanded at low pressure in an expansion valve 25 with adjustable opening and introduced to a intermediate level in column 9. Alternatively, part liquid air can be expanded at medium pressure and introduced into column 8.

Le reste de l'air surpressé en 5 est détendu à la moyenne pression dans la turbine 4 puis envoyé directement, via une conduite 26, à la base de la colonne 8.The rest of the air supercharged at 5 is expanded to medium pressure in the turbine 4 and then sent directly, via a pipe 26, to the base of the column 8.

On reconnaît par ailleurs sur la figure 1 les conduites habituelles des installations à double colonne, celle représentée étant du type dit "à minaret", c'est-à-dire avec production d'azote sous la basse pression : les conduites 27 à 29 d'injection dans la colonne 9, à des niveaux croissants de "liquide riche" (air enrichi en oxygène) détendu, de "liquide pauvre inférieur" (azote impur) détendu et de "liquide pauvre supérieur" (azote pratiquement pur) détendu, respectivement, ces trois fluides étant respectivement soutirés à la base, en un point intermédiaire et au sommet de la colonne 8, et les conduites 30 de soutirage d'azote gazeux partant du sommet de la colonne 9 et 31 d'évacuation du gaz résiduaire (azote impur) partant du niveau d'injection du liquide pauvre inférieur. L'azote basse pression est réchauffé dans des passages 32 de l'échangeur 6 puis évacué via une conduite 33, tandis que le gaz résiduaire W, après réchauffement dans des passages 34 de l'échangeur, est utilisé pour régénérer une bouteille d'adsorption, la bouteille 2B dans l'exemple considéré, avant d'être évacué via une conduite 35.We also recognize in Figure 1 the usual lines of double column installations, that shown being of the type called "minaret", that is to say with nitrogen production under low pressure: lines 27 to 29 injection into column 9, at increasing levels of relaxed "rich liquid" (oxygen-enriched air), relaxed "lower lean liquid" (impure nitrogen) and expanded "lean higher liquid" (almost pure nitrogen), respectively, these three fluids being respectively drawn off at the base, at an intermediate point and at the top of the column 8, and the pipes 30 for drawing off nitrogen gas starting from the top of the column 9 and 31 for discharging the residual gas ( impure nitrogen) from the lower lean liquid injection level. The low-pressure nitrogen is heated in passages 32 of the exchanger 6 and then discharged via a line 33, while the waste gas W, after heating in passages 34 of the exchanger, is used to regenerate an adsorption bottle , the bottle 2B in the example considered, before being evacuated via a pipe 35.

On a encore représenté sur la figure 1 une conduite 36 d'évacuation d'oxygène liquide de l'installation piquée sur la conduite de refoulement de la pompe 12.FIG. 1 also shows a pipe 36 for discharging liquid oxygen from the installation stitched on the discharge pipe of the pump 12.

La haute pression d'air, au refoulement de la soufflante, est comprise entre 25 x 10⁵ Pa environ et la pression de condensation de l'air par vaporisation de l'oxygène sous la haute pression d'oxygène. Comme expliqué dans d'autres demandes de brevet qui décrivent des procédés "à pompe" et "à paliers décalés", c'est-à-dire dans lesquels, comme dans la présente invention, l'air qui apporte la chaleur de vaporisation de l'oxygène se condense au-dessous de la température de vaporisation de cet oxygène, le bilan frigorifique de l'installation est équilibré, avec un écart de température au bout chaud de la ligne d'échange thermique de l'ordre de 3°C, en soutirant de l'installation au moins un produit, ici de l'oxygène, sous forme liquide, via la conduite 36.The high air pressure, at the discharge of the blower, is between approximately 25 x 10⁵ Pa and the condensation pressure of the air by vaporization of oxygen under the high oxygen pressure. As explained in other patent applications which describe "pump" and "offset bearing" processes, that is to say in which, as in the present invention, the air which provides the heat of vaporization of the oxygen condenses below the vaporization temperature of this oxygen, the refrigeration balance of the installation is balanced, with a temperature difference at the hot end of the heat exchange line of the order of 3 ° C. , by withdrawing from the installation at least one product, here oxygen, in liquid form, via line 36.

En fonctionnement nominal, le niveau de liquide dans le réservoir 13 est constant, ainsi que celui du réservoir 11.In nominal operation, the liquid level in the reservoir 13 is constant, as is that of the reservoir 11.

Lorsque la demande en oxygène gazeux sous pression, sur la conduite de production 15, varie, on maintient constant le débit d'air comprimé par le compresseur 1, ainsi que la pression de refoulement de ce compresseur, et on procède de la manière suivante.When the demand for gaseous oxygen under pressure, on the production line 15, varies, the flow of air compressed by the compressor 1, as well as the discharge pressure of this compressor, is kept constant, and the procedure is carried out as follows.

Lorsque la demande en oxygène diminue, on augmente l'ouverture de la vanne 25 afin d'accroître la quantité de liquide dans la colonne 9. Pour maintenir le niveau de liquide en cuve de cette colonne, la vanne 17 s'ouvre, de sorte qu'un débit accru d'oxygène liquide est envoyé dans le réservoir 11.When the oxygen demand decreases, the opening of the valve 25 is increased in order to increase the quantity of liquid in the column 9. To maintain the level of liquid in the tank of this column, the valve 17 opens, so an increased flow of liquid oxygen is sent to the tank 11.

L'air liquide contenu dans le réservoir 13 étant à la haute pression, sa chaleur latente de liquéfaction est faible, de sorte que le débit supplémentaire d'air liquide envoyé dans la colonne 9 est sensiblement plus grand que le débit supplémentaire d'oxygène que l'on soutire de celle-ci. Il est d'autant plus grand que la pression de l'air liquide est plus élevée. Par suite, la quantité de gaz froids produite par la double colonne et envoyée dans la ligne d'échange thermique augmente, compensant d'autant la réduction de la quantité de froid envoyée dans cette dernière du fait de la baisse de la demande en oxygène gazeux et, par conséquent, du débit d'oxygène vaporisé dans les passages 18, cette baisse étant obtenue en réduisant la vitesse de la pompe 12.The liquid air contained in the reservoir 13 being at high pressure, its latent heat of liquefaction is low, so that the additional flow of liquid air sent to the column 9 is substantially greater than the additional flow of oxygen than we draw from it. The greater the pressure of the liquid air, the greater it is. As a result, the quantity of cold gases produced by the double column and sent into the heat exchange line increases, compensating all the more for the reduction in the quantity of cold sent to the latter due to the decrease in the demand for gaseous oxygen. and, consequently, of the flow of oxygen vaporized in the passages 18, this reduction being obtained by reducing the speed of the pump 12.

Par conséquent, le niveau de liquide monte dans le réservoir 11 et il baisse dans ce réservoir 13.Consequently, the level of liquid rises in the reservoir 11 and it drops in this reservoir 13.

Il est à noter que l'ajout d'air liquide supplémentaire nécessite une augmentation de la puissance de distillation dans la double colonne 7, ce qui est obtenu grâce au fait que la diminution du débit d'oxygène liquide vaporisé en 6 provoque une augmentation du débit gazeux introduit dans la colonne 8.It should be noted that the addition of additional liquid air requires an increase in the distillation power in the double column 7, which is obtained thanks to the fact that the reduction in the flow rate of liquid oxygen vaporized at 6 causes an increase in the gas flow rate introduced in column 8.

Inversement, lors d'une augmentation de la demande en oxygène gazeux, on réduit l'ouverture de la vanne 25, ce qui réduit le débit d'air liquide envoyé dans la colonne 9, la vanne 17 se ferme, et on augmente la vitesse de la pompe 12. Ainsi, le niveau de liquide baisse dans le réservoir11 et augmente dans le réservoir 13.Conversely, during an increase in the demand for gaseous oxygen, the opening of the valve 25 is reduced, which reduces the flow of liquid air sent to the column 9, the valve 17 closes, and the speed is increased. of the pump 12. Thus, the liquid level drops in the tank 11 and increases in the tank 13.

Pour des raisons analogues à ce qui a été expliqué plus haut, ceci a pour conséquence une baisse de la quantité de gaz froids envoyée dans la ligne d'échange thermique, cette baisse compensant dans une large mesure l'augmentation de la quantité de froid introduite dans cette dernière du fait du débit supplémentaire d'oxygène liquide à vaporiser.For reasons similar to what has been explained above, this results in a decrease in the quantity of cold gases sent into the heat exchange line, this decrease largely compensating for the increase in the quantity of cold introduced. in the latter due to the additional flow of liquid oxygen to be vaporized.

On comprend qu'il est avantageux de stocker l'air liquide en 13 à la pression la plus élevée possible, pour amplifier les phénomènes expliqués ci-dessus. Toutefois, pour des raisons technologiques ou parce que la haute pression d'air est super-critique, on peut, en variante, détendre l'air liquide dans une vanne de détente 37 prévue dans la conduite 22, avant de l'introduire dans le réservoir 13, jusqu'à une pression intermédiaire entre la haute pression d'air et la moyenne pression de la colonne 8.It is understood that it is advantageous to store the liquid air at 13 at the highest possible pressure, to amplify the phenomena explained above. However, for technological reasons or because the high air pressure is super-critical, it is possible, as a variant, to relax the liquid air in an expansion valve 37 provided in line 22, before introducing it into the reservoir 13, up to an intermediate pressure between the high air pressure and the medium pressure of column 8.

Dans le cas où l'air liquide est stocké à une pression intermédiaire, il est intéressant, du point de vue énergétique, de ne pas comprimer à la haute pression l'air destiné au récipient de stockage 13. Ainsi, dans la variante de la figure 2, cet air est prélevé à la sortie de l'appareil 2 via une conduite 38, refroidi et liquéfié dans des passages supplémentaires 21A de la ligne d'échange, et envoyé comme précédemment au récipient 13 via la conduite 22.In the case where the liquid air is stored at an intermediate pressure, it is advantageous, from the energy point of view, not to compress at high pressure the air intended for the storage container 13. Thus, in the variant of the FIG. 2, this air is taken at the outlet of the device 2 via a pipe 38, cooled and liquefied in additional passages 21A of the exchange line, and sent as previously to the container 13 via the pipe 22.

Les passages de liquéfaction 21 de l'air sous la haute pression sont équipés, au bout froid de la ligne d'échange, d'une vanne de détente 25A, et les passages de sous-refroidissement de l'air liquide soutiré du récipient 13 sont équipés, au même bout froid, de la vanne de détente 25.The liquefaction passages 21 of the air under high pressure are equipped, at the cold end of the exchange line, with an expansion valve 25A, and the sub-cooling passages of the liquid air withdrawn from the container 13 are equipped, at the same cold end, with the expansion valve 25.

Dans cette variante, c'est la commande des vannes 25 et 25A qui assure le fonctionnement de la bascule air/oxygène, analogue par ailleurs à ce qui a été décrit plus haut en regard de la figure 1.In this variant, it is the control of the valves 25 and 25A which ensures the operation of the air / oxygen rocker, similar moreover to what has been described above with reference to FIG. 1.

La gamme de pressions optimales, du point de vue de l'équilibre thermique de la ligne d'échange 6 et de celui des conditions de distillation, est comprise entre 30 x 10⁵ Pa et 35 x 10⁵ Pa environ.The optimum pressure range, from the point of view of the thermal equilibrium of the exchange line 6 and that of the distillation conditions, is between approximately 30 × 10⁵ Pa and approximately 35 × 10⁵ Pa.

L'invention s'applique également au cas où le liquide soutiré est de l'azote, de l'argon ou un autre liquide.The invention also applies to the case where the liquid withdrawn is nitrogen, argon or another liquid.

Claims (12)

Procédé de production d'un gaz sous pression à débit variable, du type dans lequel on distille de l'air dans une installation de distillation d'air comprenant un appareil de distillation (7) et une ligne d'échange thermique (6) pour refroidir l'air par échange de chaleur avec des produits provenant de l'appareil de distillation ; on soutire du liquide de cet appareil, on l'amène à une pression de vaporisation, on le vaporise et on le réchauffe sous cette pression dans la ligne d'échange thermique pour former le gaz sous pression, cette vaporisation et ce réchauffement s'accompagnant d'une liquéfaction d'air dans ses passages de liquéfaction d'air de la ligne d'échange thermique; et dans lequel : - lors d'une réduction de la demande du gaz sous pression par rapport au débit nominal, on soutire de l'appareil de distillation, sous forme liquide, I'excédent produit par cet appareil, on envoie ce liquide dans un récipient (11) de stockage de liquide, et on introduit dans l'appareil de distillation (7) une quantité additionnelle correspondante d'air liquide préalablement stocké (13) ; et - lors d'une augmentation de la demande d'oxygène gazeux sous pression par rapport au débit nominal, on soutire l'excès demandé, sous forme liquide, du récipient de stockage du liquide soutiré (11), on l'amène (en 12) à la pression de vaporisation, et on le vaporise sous cette pression (en 18) dans la ligne d'échange thermique (6), et on stocke une quantité correspondante d'air liquéfié par ladite liquéfaction dans le récipient de stockage d'air liquide (13),    caractérisé en ce que l'on stocke le liquide soutiré sous une pression voisine de la pression atmosphérique tandis que l'on stocke l'air liquide sous une pression de stockage au moins égale, et de préférence nettement supérieure, à la plus forte pression de fonctionnement de l'appareil de distillation.Method for producing a pressurized gas with variable flow rate, of the type in which air is distilled in an air distillation installation comprising a distillation apparatus (7) and a heat exchange line (6) for cooling the air by heat exchange with products from the distillation apparatus; liquid is drawn from this device, it is brought to a vaporization pressure, it is vaporized and it is heated under this pressure in the heat exchange line to form the gas under pressure, this vaporization and this heating being accompanied air liquefaction in its air liquefaction passages of the heat exchange line; and in which: - when the demand for pressurized gas is reduced compared to the nominal flow rate, the excess produced by this distillation apparatus is drawn off in liquid form, this liquid is sent to a container (11) liquid storage, and is introduced into the distillation apparatus (7) a corresponding additional amount of previously stored liquid air (13); and - when the demand for gaseous oxygen under pressure increases compared to the nominal flow rate, the requested excess is withdrawn, in liquid form, from the container for storing the withdrawn liquid (11), it is brought (at 12 ) at the vaporization pressure, and it is vaporized under this pressure (at 18) in the heat exchange line (6), and a corresponding quantity of air liquefied by said liquefaction is stored in the air storage container liquid (13), characterized in that the liquid withdrawn is stored under a pressure close to atmospheric pressure while the liquid air is stored under a storage pressure at least equal, and preferably significantly higher, at the higher pressure of operation of the distillation apparatus. Procédé selon la revendication 1, caractérisé en ce que le récipient de stockage d'air liquide (13) est à une pression voisine de la pression à laquelle s'effectue ladite liquéfaction d'air.Method according to claim 1, characterized in that the liquid air storage container (13) is at a pressure close to the pressure at which said air liquefaction takes place. Procédé selon la revendication 1 ou 2, caractérisé en ce que le récipient de stockage d'air liquide (13) est à une pression comprise entre 30 x 10⁵ Pa et 35 x 10⁵ Pa environ.Method according to claim 1 or 2, characterized in that the liquid air storage container (13) is at a pressure between approximately 30 x 10⁵ Pa and 35 x 10⁵ Pa. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que la totalité du liquide vaporisé est soutirée du récipient de stockage de liquide (11).Method according to any one of Claims 1 to 3, characterized in that all of the vaporized liquid is withdrawn from the liquid storage container (11). Procédé selon l'une quelconque des revendications 1 à 4, caractérisé en ce que l'on effectue ladite liquéfaction d'air à une température inférieure à la température de vaporisation du liquide soutiré sous ladite pression de vaporisation, et on évacue au moins un produit liquide de l'installation.Process according to any one of Claims 1 to 4, characterized in that said air liquefaction is carried out at a temperature below the vaporization temperature of the liquid drawn off under said vaporization pressure, and at least one product is discharged installation liquid. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce qu'on comprime (en 1) l'air destiné au récipient (13) de stockage d'air liquide à ladite pression de stockage et le reste de l'air à une haute pression supérieure à cette pression de stockage.Method according to any one of Claims 1 to 5, characterized in that the air intended for the container (13) for storing liquid air is compressed to said storage pressure and the rest of the air at a high pressure higher than this storage pressure. Installation de production d'un gaz sous pression à débit variable, du type comprenant un appareil de distillation d'air (7), une ligne d'échange thermique (6) pour refroidir l'air par échange de chaleur avec des produits provenant de l'appareil de distillation, des moyens (16, 17) pour soutirer du liquide de cet appareil ; des moyens (12) pour amener au moins une fraction de l'air à distiller à une haute pression, et l'envoyer dans des passages (21 ; 21, 21A) de liquéfaction d'air de la ligne d'échange thermique, un récipient (11) de stockage de liquide relié à l'appareil de distillation (7) et muni de moyens (12) pour soutirer du liquide à débit réglable, l'amener à la pression de vaporisation et l'envoyer dans des passages (18) de vaporisation de la ligne d'échange thermique, et un récipient (13) de stockage d'air liquide relié en amont aux passages (21 ; 21, 21A) de liquéfaction d'air de la ligne d'échange thermique et, en aval, et via des moyens de détente (25) à débit réglable, à l'appareil de distillation,
   caractérisée en ce que le récipient (11) du liquide soutiré se trouve sous une pression voisine de la pression atmosphérique, tandis que le récipient (13) de stockage d'air liquide se trouve sous une pression nettement supérieure à la plus forte pression de fonctionnement de l'appareil de distillation (7).Installation for producing a pressurized gas with variable flow rate, of the type comprising an air distillation apparatus (7), a heat exchange line (6) for cooling the air by heat exchange with products from the distillation apparatus, means (16, 17) for withdrawing liquid from this apparatus; means (12) for bringing at least a fraction of the air to be distilled to a high pressure, and sending it through passages (21; 21, 21A) for liquefying air from the heat exchange line, a liquid storage container (11) connected to the distillation apparatus (7) and provided with means (12) for withdrawing liquid with adjustable flow rate, bringing it to the vaporization pressure and sending it into passages (18 ) of vaporization of the heat exchange line, and a container (13) for storing liquid air connected upstream to the passages (21; 21, 21A) for air liquefaction of the heat exchange line and, in downstream, and via expansion means (25) with adjustable flow, to the distillation apparatus,
characterized in that the container (11) for the withdrawn liquid is under a pressure close to atmospheric pressure, while the container (13) for storing liquid air is at a pressure significantly higher than the highest operating pressure of the distillation apparatus (7). Installation selon la revendication 7, caractérisée en ce que le récipient de stockage d'air liquide (13) est à une pression voisine de la pression à laquelle s'effectue ladite liquéfaction d'air.Installation according to claim 7, characterized in that the liquid air storage container (13) is at a pressure close to the pressure at which said air liquefaction takes place. Installation selon la revendication 7 ou 8, caractérisée en ce que le récipient de stockage d'air liquide (13) est à une pression comprise entre 30 x 10⁵ Pa et 35 x 10⁵ Pa environ.Installation according to claim 7 or 8, characterized in that the liquid air storage container (13) is at a pressure between approximately 30 x 10⁵ Pa and 35 x 10⁵ Pa. Installation selon l'une quelconque des revendications 7 à 9, caractérisée en ce que le récipient (11) de stockage du liquide est interposé entre l'appareil de distillation d'air (7) et des moyens (12) pour amener à la pression de vaporisation la totalité du liquide à vaporiser.Installation according to any one of claims 7 to 9, characterized in that the container (11) for storing the liquid is interposed between the air distillation apparatus (7) and means (12) for bringing to the pressure all the liquid to be vaporized. Installation selon l'une quelconque des revendications 7 à 10, caractérisée en ce que le récipient de stockage d'air liquide (13) est relié auxdits passages de liquéfaction d'air (21 ; 21A) par l'intermédiaire d'une vanne de détente (37).Installation according to any one of claims 7 to 10, characterized in that the liquid air storage container (13) is connected to said air liquefaction passages (21; 21A) by means of a valve. trigger (37). Installation selon l'une quelconque des revendications 7 à 11, caractérisée en ce que les moyens de compression (1, 5) comprennent un compresseur d'air principal (1) suivi d'une soufflante (5) adaptée pour surpresser une fraction de l'air non destinée au récipient (13) de stockage d'air liquide.Installation according to any one of claims 7 to 11, characterized in that the compression means (1, 5) comprise a main air compressor (1) followed by a blower (5) adapted to overpress a fraction of l air not intended for the container (13) for storing liquid air.
EP95401774A 1994-07-29 1995-07-26 Process for the production of a gas under pressure in variable quantities Expired - Lifetime EP0694746B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9409481 1994-07-29
FR9409481A FR2723184B1 (en) 1994-07-29 1994-07-29 PROCESS AND PLANT FOR THE PRODUCTION OF GAS OXYGEN UNDER PRESSURE WITH VARIABLE FLOW RATE

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EP0694746A1 true EP0694746A1 (en) 1996-01-31
EP0694746B1 EP0694746B1 (en) 2000-04-19

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EP (1) EP0694746B1 (en)
JP (1) JPH08170875A (en)
KR (1) KR100394311B1 (en)
CN (1) CN1119607C (en)
CA (1) CA2154984A1 (en)
DE (1) DE69516339T2 (en)
ES (1) ES2145885T3 (en)
FR (1) FR2723184B1 (en)
ZA (1) ZA956332B (en)

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Also Published As

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ZA956332B (en) 1996-03-11
US5526647A (en) 1996-06-18
JPH08170875A (en) 1996-07-02
EP0694746B1 (en) 2000-04-19
FR2723184A1 (en) 1996-02-02
KR100394311B1 (en) 2003-10-22
CA2154984A1 (en) 1996-01-30
KR960003774A (en) 1996-02-23
DE69516339T2 (en) 2000-09-21
CN1119607C (en) 2003-08-27
ES2145885T3 (en) 2000-07-16
CN1154463A (en) 1997-07-16
DE69516339D1 (en) 2000-05-25
FR2723184B1 (en) 1996-09-06

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