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EP0914584B1 - Method and plant for producing an air gas with a variable flow rate - Google Patents

Method and plant for producing an air gas with a variable flow rate Download PDF

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Publication number
EP0914584B1
EP0914584B1 EP97935636A EP97935636A EP0914584B1 EP 0914584 B1 EP0914584 B1 EP 0914584B1 EP 97935636 A EP97935636 A EP 97935636A EP 97935636 A EP97935636 A EP 97935636A EP 0914584 B1 EP0914584 B1 EP 0914584B1
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EP
European Patent Office
Prior art keywords
flow
liquid
auxiliary
gas
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP97935636A
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German (de)
French (fr)
Other versions
EP0914584A1 (en
Inventor
Bernard Darredeau
Alain Guillard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by Air Liquide SA, LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude filed Critical Air Liquide SA
Publication of EP0914584A1 publication Critical patent/EP0914584A1/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02Processes 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
    • F25J3/04Processes 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02Processes 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
    • F25J3/04Processes 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
    • F25J3/04472Processes 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
    • F25J3/04496Processes 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
    • F25J3/04503Processes 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
    • F25J3/04509Processes 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
    • F25J3/04515Simultaneously changing air feed and products output
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02Processes 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
    • F25J3/04Processes 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
    • F25J3/04006Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078Providing 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
    • F25J3/0409Providing 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02Processes 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
    • F25J3/04Processes 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
    • F25J3/04248Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284Generation 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
    • F25J3/0429Generation 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
    • F25J3/04303Lachmann expansion, i.e. expanded into oxygen producing or low pressure column
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02Processes 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
    • F25J3/04Processes 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
    • F25J3/04406Processes 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
    • F25J3/04412Processes 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02Processes 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
    • F25J3/04Processes 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
    • F25J3/04763Start-up or control of the process; Details of the apparatus used
    • F25J3/04769Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04812Different modes, i.e. "runs" of operation
    • F25J3/04836Variable air feed, i.e. "load" or product demand during specified periods, e.g. during periods with high respectively low power costs
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00Processes or apparatus using other separation and/or other processing means
    • F25J2205/02Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/50Processes or apparatus involving steps for increasing the pressure of gaseous process streams the fluid being oxygen
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00Processes or apparatus involving steps for expanding of process streams
    • F25J2240/40Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • F25J2240/46Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval the fluid being oxygen
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00Processes or apparatus involving steps for recycling of process streams
    • F25J2245/50Processes or apparatus involving steps for recycling of process streams the recycled stream being oxygen
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25JLIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2290/00Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/62Details of storing a fluid in a tank

Definitions

  • the present invention relates to a method for producing an air gas, in particular oxygen, at variable flow by air distillation, of the type described in the preamble of claim 1.
  • the invention applies in particular to the production of oxygen under pressure with variable flow.
  • the pressures discussed here are absolute pressures, and flow rates are flow rates molars.
  • EP-A-0 422 974 in the name of the Applicant describes a process of this type, called a "rocking process", intended for the production of gaseous oxygen with variable flow.
  • the second fluid in question is air to be distilled, which is condensed at a variable rate.
  • the compressor, and possibly the booster are significantly oversized compared to the flow nominal oxygen to be produced.
  • they work for the majority of the time at high flows reduced compared to their capacities, and therefore with a degraded yield.
  • the invention aims to allow the production of air gas with variable flow in particularly effective and economical conditions.
  • This process can include one or more of Features of claims 2 to 11.
  • the subject of the invention is also a installation intended for the implementation of such process. This installation is described in the claim 12.
  • This installation may include one or more several of the features of claims 13 to 16.
  • the installation shown in Figure 1 basically includes a main air compressor 1 with variable flow, for example of the centrifugal type with blades mobile, an adsorption purification device 2, a heat exchange line 3, a turbine 4 for maintaining cold, an air distillation apparatus 5 consisting of a double column including itself a column medium pressure 6 surmounted by a low pressure column 7 and a vaporizer-condenser 8, a reservoir liquid oxygen 10, a liquefied air tank 11, two pumps 12 and 13, an air booster 14 and a capacity auxiliary or "buffer" 15.
  • This installation is intended to produce a variable flow of gaseous oxygen via a production line 16, at a pressure of around 15 bars.
  • a first flow is cooled in passages 19 of exchange line 3; some came out of this exchange line after partial cooling, expanded to around 1 bar in turbine 4 and blown into the low pressure column 7 near its point of dew via line 20; the rest continues cooling to the vicinity of its dew point under 6 bars, then is injected at the bottom of the middle column pressure 6 via line 21.
  • a second flow is boosted at 14 to a high condensing pressure defined below, then is cooled and liquefied in passages 22 of the line then stored in liquid form in the tank 11 after expansion to 6 bars in a valve trigger 23.
  • a constant flow of liquefied air is drawn off from the bottom of this tank and is divided into a first flow constant at 6 bars sent in the middle column pressure via line 24, and in a second flow constant relaxed towards 1 bar in an expansion valve 25 then injected into the low pressure column 7.
  • the vaporizer-condenser 8 vaporizes a flow liquid oxygen constant in bottom column tank pressure 7 by condensation of an approximately equal flow nitrogen at the top of the medium pressure column 6.
  • Du "rich liquid” (oxygen-enriched air) taken from tank of the medium pressure column and relaxed to 1 bar in an expansion valve 26 is injected at a level intermediate of the low pressure column, and of the “liquid poor "(almost pure nitrogen), taken at the head of the medium pressure column and relaxed to 1 bar in one expansion valve 27, is injected at the top of the column low pressure.
  • Capacity 15 is connected to the conduct of production 16 via a line 33 fitted with a valve trigger and flow control 34, and a constant flow equal to that of the aforementioned second stream is relaxed in this valve 34 and sent from capacity 15 to line 16.
  • the installation includes a single blower 14, so that the condensation of pressurized air is used, in passages 22 of the exchange line, to vaporize both the oxygen under 15 bars and oxygen under 30 bars.
  • the pressure of the supercharged air is chosen as being the pressure known as "concomitant" with the vaporization of oxygen under 15 bars.
  • This pressure is that for which the knee G of air liquefaction is close to the stage P of vaporization of oxygen under 15 bars, as shown in FIG. 2, on which the quantities of heat exchanged Q are plotted on the ordinate and temperatures t on the abscissa.
  • point A represents the inlet temperature of turbine 4, and this inlet temperature is chosen so as to obtain a minimum temperature difference, of the order of a few degrees, at the warm end of the exchange line.
  • oxygen is produced under 1 bar approximately, and the oxygen demand is still greater than a given minimum value.
  • a flow constant gaseous oxygen equal to this minimum value can then be drawn directly from the bottom of the column low pressure 7 via a pipe 35, as indicated in dashed line in Figure 1, then reheated in the line exchange.
  • This variant reduces the capacity tanks 10 and 11.
  • production constants of liquid oxygen and / or nitrogen gas and / or liquid nitrogen can be supplied simultaneously by the double column, via lines 36 and / or 37 and / or 38, also as shown in phantom in Figure 1.
  • the pump 13 is deleted.
  • the auxiliary oxygen flow is withdrawn in gaseous form from the tank of column 7, via a pipe 39, is heated at 30 below the low pressure and then is compressed at high pressure by a auxiliary compressor 40 before being introduced into the capacity 15.
  • the vaporizing fluid at least one of the two oxygen flow rates is nitrogen.
  • the main flow is sprayed using the vaporizer 8 of the double column. This main flow is then withdrawn in gaseous form from the column tank 7, via a pipe 41, and heated at 29.
  • the discharge pump 12 is then connected to the column tank, which feeds the tank 10 by gravity.
  • line 38 is connected to a nitrogen tank 42, and the bottom of this tank is connected to a pump 43 for returning a constant flow of nitrogen liquid at the top of column 6.
  • the rocker is, in this variant, a rocker oxygen / nitrogen, and the reservoir 11, at constant level, can be deleted.

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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)
  • Respiratory Apparatuses And Protective Means (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)

Abstract

A plant which, when used to produce pressurised oxygen gas, includes a switch, e.g. a liquid oxygen/liquid air switch, for meeting relatively long-term peak demand as well as short-term, high-amplitude peak demand, and a circuit (13, 30) for compressing oxygen to a pressure higher than the production pressure. Said circuit leads to a buffer (15) at least partially meeting short-term, high-amplitude peak demand.

Description

La présente invention est relative à un procédé de production d'un gaz de l'air, notamment d'oxygène, à débit variable par distillation d'air, du type décrit dans le préambule de la revendication 1.The present invention relates to a method for producing an air gas, in particular oxygen, at variable flow by air distillation, of the type described in the preamble of claim 1.

L'invention s'applique en particulier à la production d'oxygène sous pression à débit variable.The invention applies in particular to the production of oxygen under pressure with variable flow.

Les pressions dont il est question ici sont des pressions absolues, et les débits sont des débits molaires.The pressures discussed here are absolute pressures, and flow rates are flow rates molars.

Le EP-A-0 422 974 au nom de la Demanderesse décrit un procédé de ce type, dit "procédé à bascule", destiné à la production d'oxygène gazeux à débit variable. Le second fluide en question est de l'air à distiller, qui est condensé suivant un débit variable.EP-A-0 422 974 in the name of the Applicant describes a process of this type, called a "rocking process", intended for the production of gaseous oxygen with variable flow. The second fluid in question is air to be distilled, which is condensed at a variable rate.

Dans ce procédé connu, il est facile de montrer que pour maintenir constants les débits d'alimentation et de soutirage de l'appareil de distillation, il est nécessaire de faire varier le débit d'air entrant dans le même sens que les variations de la consommation d'oxygène. Dans le cas où l'oxygène est produit sous pression, l'air que l'on condense pour vaporiser l'oxygène liquide est surpressé par un surpresseur additionnel, et, lorsque la demande en oxygène varie, il faut faire varier de façon importante à la fois le débit surpressé et le débit comprimé par le compresseur principal.In this known process, it is easy to show that to keep the feed rates constant and of the distillation apparatus, it is necessary to vary the air flow entering the same direction as variations in oxygen consumption. In the case where oxygen is produced under pressure, the air that we condense to vaporize liquid oxygen is boosted by an additional booster, and, when the oxygen demand varies, you have to vary it important both the boosted flow and the flow compressed by the main compressor.

Par conséquent, dans ce procédé connu, le compresseur, et éventuellement le surpresseur, sont surdimensionnés de façon importante par rapport au débit nominal d'oxygène à produire. De plus, ils travaillent pendant la majorité du temps à des débits fortement réduits par rapport à leurs capacités, et donc avec un rendement dégradé.Therefore, in this known method, the compressor, and possibly the booster, are significantly oversized compared to the flow nominal oxygen to be produced. In addition, they work for the majority of the time at high flows reduced compared to their capacities, and therefore with a degraded yield.

Il a également été proposé de stocker du gaz à produire, sous forme gazeuse, dans une capacité auxiliaire ou "buffer", à une pression supérieure à la pression de production. Cependant, cette solution n'est pas satisfaisante, car elle nécessite la mise en place de buffers de très grande dimension pour faire face à des pointes de consommation de longue durée. De plus, la production de la totalité du gaz à la pression du buffer est coûteuse en énergie.It has also been proposed to store gas at produce, in gaseous form, in an auxiliary capacity or "buffer", at a pressure higher than the pressure of production. However, this solution is not satisfactory because it requires the installation of very large buffers to deal with long-term consumption peaks. In addition, the production of all gas at buffer pressure is costly in energy.

L'invention a pour but de permettre la production de gaz de l'air à débit variable dans des conditions particulièrement efficaces et économiques.The invention aims to allow the production of air gas with variable flow in particularly effective and economical conditions.

A cet effet, elle a pour objet un procédé du type précité, caractérisé par la partie caractérisante de la revendication 1.To this end, it relates to a process of aforementioned type, characterized by the characterizing part of claim 1.

Ce procédé peut comporter une ou plusieurs des caractéristiques des revendications 2 à 11.This process can include one or more of Features of claims 2 to 11.

L'invention a également pour objet une installation destinée à la mise en oeuvre d'un tel procédé. Cette installation est décrite dans la revendication 12.The subject of the invention is also a installation intended for the implementation of such process. This installation is described in the claim 12.

Cette installation peut comporter une ou plusieurs des caractéristiques des revendications 13 à 16.This installation may include one or more several of the features of claims 13 to 16.

Un exemple de mise en oeuvre de l'invention va maintenant être décrit en regard des dessins annexés, sur lesquels :

  • la Figure 1 représente schématiquement une installation de production d'oxygène sous pression à débit variable conforme à l'invention ;
  • la Figure 2 est un diagramme d'échange thermique illustrant la vaporisation de l'oxygène liquide sous la pression de production ; et
  • les Figures 3 et 4 représentent schématiquement deux variantes de l'installation.
An example of implementation of the invention will now be described with reference to the accompanying drawings, in which:
  • Figure 1 schematically shows an installation for producing oxygen under pressure with variable flow rate according to the invention;
  • Figure 2 is a heat exchange diagram illustrating the vaporization of liquid oxygen under production pressure; and
  • Figures 3 and 4 schematically represent two variants of the installation.

L'installation représentée à la Figure 1 comprend essentiellement un compresseur d'air principal 1 à débit variable, par exemple du type centrifuge à aubages mobiles, un appareil d'épuration par adsorption 2, une ligne d'échange thermique 3, une turbine 4 de maintien en froid, un appareil 5 de distillation d'air constitué par une double colonne comprenant elle-même une colonne moyenne pression 6 surmontée d'une colonne basse pression 7 ainsi qu'un vaporiseur-condenseur 8, un réservoir d'oxygène liquide 10, un réservoir d'air liquéfié 11, deux pompes 12 et 13, un surpresseur d'air 14 et une capacité auxiliaire ou "buffer" 15. Cette installation est destinée à produire un débit variable d'oxygène gazeux via une conduite de production 16, sous une pression d'environ 15 bars.The installation shown in Figure 1 basically includes a main air compressor 1 with variable flow, for example of the centrifugal type with blades mobile, an adsorption purification device 2, a heat exchange line 3, a turbine 4 for maintaining cold, an air distillation apparatus 5 consisting of a double column including itself a column medium pressure 6 surmounted by a low pressure column 7 and a vaporizer-condenser 8, a reservoir liquid oxygen 10, a liquefied air tank 11, two pumps 12 and 13, an air booster 14 and a capacity auxiliary or "buffer" 15. This installation is intended to produce a variable flow of gaseous oxygen via a production line 16, at a pressure of around 15 bars.

Pour décrire le fonctionnement de cette installation, on supposera tout d'abord que la demande d'oxygène gazeux dans la conduite 16 est constante et égale à la production nominale, soit environ 20 % du débit d'air nominal comprimé par le compresseur 1.To describe how this installation, we will first assume that the request of gaseous oxygen in line 16 is constant and equal to the nominal production, about 20% of the flow nominal air compressed by compressor 1.

Le débit nominal d'air à traiter, comprimé à 6 bars par le compresseur 1 et refroidi à la température ambiante par un réfrigérant 17 à air ou à eau, est épuré dans l'appareil 2, puis divisé en deux flux ayant chacun un débit constant.The nominal flow of air to be treated, compressed to 6 bars by compressor 1 and cooled to temperature room by air or water cooler 17, is purified in device 2, then divided into two streams each having a constant flow.

Un premier flux est refroidi dans des passages 19 de la ligne d'échange 3 ; une partie est sortie de cette ligne d'échange après un refroidissement partiel, détendue vers 1 bar dans la turbine 4 et insufflée dans la colonne basse pression 7 au voisinage de son point de rosée via une conduite 20 ; le reste poursuit son refroidissement jusqu'au voisinage de son point de rosée sous 6 bars, puis est injecté au bas de la colonne moyenne pression 6 via une conduite 21.A first flow is cooled in passages 19 of exchange line 3; some came out of this exchange line after partial cooling, expanded to around 1 bar in turbine 4 and blown into the low pressure column 7 near its point of dew via line 20; the rest continues cooling to the vicinity of its dew point under 6 bars, then is injected at the bottom of the middle column pressure 6 via line 21.

Un second flux est surpressé en 14 jusqu'à une haute pression de condensation définie plus loin, puis est refroidi et liquéfié dans des passages 22 de la ligne d'échange, puis stocké sous forme liquide dans le réservoir 11 après détente à 6 bars dans une vanne de détente 23. Un débit constant d'air liquéfié est soutiré du fond de ce réservoir et est divisé en un premier débit constant sous 6 bars envoyé dans la colonne moyenne pression via une conduite 24, et en un second débit constant détendu vers 1 bar dans une vanne de détente 25 puis injecté dans la colonne basse pression 7.A second flow is boosted at 14 to a high condensing pressure defined below, then is cooled and liquefied in passages 22 of the line then stored in liquid form in the tank 11 after expansion to 6 bars in a valve trigger 23. A constant flow of liquefied air is drawn off from the bottom of this tank and is divided into a first flow constant at 6 bars sent in the middle column pressure via line 24, and in a second flow constant relaxed towards 1 bar in an expansion valve 25 then injected into the low pressure column 7.

Le vaporisateur-condenseur 8 vaporise un débit constant d'oxygène liquide en cuve de la colonne basse pression 7 par condensation d'un débit à peu près égal d'azote de tête de la colonne moyenne pression 6. Du "liquide riche" (air enrichi en oxygène) prélevé en cuve de la colonne moyenne pression et détendu vers 1 bar dans une vanne de détente 26 est injecté à un niveau intermédiaire de la colonne basse pression, et du "liquide pauvre "(azote à peu près pur), prélevé en tête de la colonne moyenne pression et détendu vers 1 bar dans une vanne de détente 27, est injecté au sommet de la colonne basse pression.The vaporizer-condenser 8 vaporizes a flow liquid oxygen constant in bottom column tank pressure 7 by condensation of an approximately equal flow nitrogen at the top of the medium pressure column 6. Du "rich liquid" (oxygen-enriched air) taken from tank of the medium pressure column and relaxed to 1 bar in an expansion valve 26 is injected at a level intermediate of the low pressure column, and of the "liquid poor "(almost pure nitrogen), taken at the head of the medium pressure column and relaxed to 1 bar in one expansion valve 27, is injected at the top of the column low pressure.

Un débit constant d'oxygène liquide, correspondant à environ 20 % du débit d'air entrant, passe, via une conduite 28, dans le réservoir 10. Un débit constant identique d'oxygène liquide est soutiré du fond de ce réservoir et divisé en deux flux à débits constants:

  • Un premier flux majoritaire, représentant par exemple 80 % du débit total, est comprimé à 15 bars par la pompe 12, puis vaporisé dans des passages 29 de la ligne d'échange et fourni à la conduite 16 de production.
  • Un second flux est comprimé par la pompe 13 à une pression très supérieure, par exemple 30 bars, vaporisé dans des passages 30 de la ligne d'échange et fourni à la capacité 15.
A constant flow of liquid oxygen, corresponding to approximately 20% of the flow of incoming air, passes, via a line 28, into the tank 10. An identical constant flow of liquid oxygen is withdrawn from the bottom of this tank and divided into two flows at constant rates:
  • A first majority flow, representing for example 80% of the total flow, is compressed to 15 bars by the pump 12, then vaporized in passages 29 of the exchange line and supplied to the production line 16.
  • A second flow is compressed by the pump 13 to a much higher pressure, for example 30 bars, vaporized in passages 30 of the exchange line and supplied to the capacity 15.

La capacité 15 est reliée à la conduite de production 16 via une conduite 33 équipée d'une vanne de détente et de réglage de débit 34, et un débit constant égal à celui du second flux précité est détendu dans cette vanne 34 et envoyé de la capacité 15 à la conduite 16.Capacity 15 is connected to the conduct of production 16 via a line 33 fitted with a valve trigger and flow control 34, and a constant flow equal to that of the aforementioned second stream is relaxed in this valve 34 and sent from capacity 15 to line 16.

En outre, un débit constant d'azote impur, soutiré du sommet de la colonne basse pression, est réchauffé dans des passages 31 de la ligne d'échange et évacué en tant que résiduaire via une conduite 32.In addition, a constant flow of impure nitrogen, withdrawn from the top of the low pressure column, is heated in passages 31 of the exchange line and evacuated as waste via a pipe 32.

Comme on le voit, l'installation comporte un surpresseur unique 14, de sorte que la condensation de l'air surpressé est utilisée, dans les passages 22 de la ligne d'échange, pour vaporiser à la fois l'oxygène sous 15 bars et l'oxygène sous 30 bars.As we can see, the installation includes a single blower 14, so that the condensation of pressurized air is used, in passages 22 of the exchange line, to vaporize both the oxygen under 15 bars and oxygen under 30 bars.

Pour cela, on choisit la pression de l'air surpressé comme étant la pression dite "concomitante" à la vaporisation d'oxygène sous 15 bars. Cette pression est celle pour laquelle le genou G de liquéfaction de l'air est voisin du palier P de vaporisation de l'oxygène sous 15 bars, comme représenté sur la Figure 2, sur laquelle les quantités de chaleur échangées Q sont portées en ordonnées et les températures t en abscisses.For this, the pressure of the supercharged air is chosen as being the pressure known as "concomitant" with the vaporization of oxygen under 15 bars. This pressure is that for which the knee G of air liquefaction is close to the stage P of vaporization of oxygen under 15 bars, as shown in FIG. 2, on which the quantities of heat exchanged Q are plotted on the ordinate and temperatures t on the abscissa.

Sous cette pression, le genou G précité se trouve à une température inférieure au palier P' de vaporisation de l'oxygène sous 30 bars, comme illustré également sur le diagramme de la Figure 2, mais ceci est tout à fait possible à condition d'évacuer simultanément un produit liquide de l'installation (oxygène ou azote liquide dans cet exemple), suivant l'enseignement du FR-A-2 674 011.Under this pressure, the aforementioned knee G found at a temperature below the level P 'of vaporization of oxygen at 30 bar, as illustrated also on the diagram in Figure 2, but this is completely possible provided you evacuate simultaneously a liquid product from the installation (oxygen or nitrogen liquid in this example), following the teaching of FR-A-2 674,011.

Sur la Figure 2, le point A représente la température d'admission de la turbine 4, et cette température d'admission est choisie de manière à obtenir un écart de température minimal, de l'ordre de quelques degrés, au bout chaud de la ligne d'échange.In Figure 2, point A represents the inlet temperature of turbine 4, and this inlet temperature is chosen so as to obtain a minimum temperature difference, of the order of a few degrees, at the warm end of the exchange line.

A titre d'exemple numérique, on peut choisir une pression d'air surpressé d'environ 40 bars. As a numerical example, we can choose a compressed air pressure of around 40 bars.

Toutes les conduites qui aboutissent à la double colonne 5 et toutes celles qui en partent sont équipées de moyens (non représentés) assurant un débit constant. Ainsi, lorsque la demande d'oxygène gazeux varie, le réglage de cette double colonne n'est pas modifié. De plus, le débit d'oxygène vaporisé en 30 sous la haute pression reste constant.All the pipes that lead to double column 5 and all those leaving it are equipped with means (not shown) ensuring a constant flow. Thus, when the demand for gaseous oxygen varies, the setting of this double column is not modified. Of plus, the flow of oxygen vaporized in 30 below the high pressure remains constant.

Lorsque la demande en oxygène augmente, plusieurs cas sont à distinguer :

  • (1) Si la pointe de consommation est limitée en amplitude à une valeur prédéterminée, par exemple à une valeur égale à 120 % du débit nominal, on prélève un débit supplémentaire correspondant d'oxygène liquide du réservoir 10 au moyen de la pompe 12, en augmentant le débit de pompage de celle-ci, et on le vaporise en 29 sous la pression de production par condensation, en 22, d'air surpressé par le surpresseur 14. Ceci correspond au fonctionnement classique de la bascule oxygène liquide/air liquide : le niveau d'oxygène liquide baisse dans le réservoir 10, tandis que le niveau monte dans le réservoir 11.
  • (2) Si la pointe de consommation est supérieure en amplitude à ladite valeur prédéterminée, deux cas sont à distinguer :
  • (a) Si la durée de la pointe de consommation est brève, le débit d'oxygène complémentaire nécessaire, au-delà de la valeur précitée, est prélevé dans la capacité 15, par ouverture plus grande de la vanne 34, et envoyé après détente dans cette vanne dans la conduite de production 16. Par exemple, pour une pointe de consommation égale à 160 % du débit nominal, 20 % de débit supplémentaire sont fournis par la pompe 12, et les 40 % restants par la capacité 15.
  • (b) Cependant, on comprend que, lorsqu'on prélève un débit supplémentaire de la capacité 15, la pression de celle-ci chute. Par suite, si la pointe de consommation a une durée excessive, le débit d'oxygène supplémentaire, par rapport au débit nominal, doit nécessairement être fourni par des moyens extérieurs, par exemple par un stockage auxiliaire d'oxygène.
  • When the demand for oxygen increases, several cases should be distinguished:
  • (1) If the peak consumption is limited in amplitude to a predetermined value, for example to a value equal to 120% of the nominal flow, a corresponding additional flow of liquid oxygen from the tank 10 is taken by means of the pump 12, by increasing the pumping rate thereof, and it is vaporized at 29 under the production pressure by condensation, at 22, of air supercharged by the booster 14. This corresponds to the conventional operation of the liquid oxygen / liquid air rocker : the level of liquid oxygen drops in tank 10, while the level rises in tank 11.
  • (2) If the peak consumption is greater in amplitude than said predetermined value, two cases are to be distinguished:
  • (a) If the duration of the consumption peak is short, the necessary additional oxygen flow rate, beyond the aforementioned value, is taken from capacity 15, by larger opening of valve 34, and sent after expansion in this valve in the production line 16. For example, for a peak consumption equal to 160% of the nominal flow, 20% of additional flow is supplied by the pump 12, and the remaining 40% by the capacity 15.
  • (b) However, it is understood that, when an additional flow rate is taken from the capacity 15, the pressure of the latter drops. Consequently, if the consumption peak has an excessive duration, the additional oxygen flow, compared to the nominal flow, must necessarily be supplied by external means, for example by auxiliary oxygen storage.
  • Il est à noter que l'invention s'applique également au cas suivant : l'oxygène est produit sous 1 bar environ, et la demande d'oxygène est toujours supérieure à une valeur minimale donnée. Un débit d'oxygène gazeux constant égal à cette valeur minimale peut alors être soutiré directement du bas de la colonne basse pression 7 via une conduite 35, comme indiqué en trait mixte sur la Figure 1, puis réchauffé dans la ligne d'échange. Cette variante permet de réduire la capacité des réservoirs 10 et 11. De même, des productions constantes d'oxygène liquide et/ou d'azote gazeux et/ou d'azote liquide peuvent être assurées simultanément par la double colonne, via des conduites 36 et/ou 37 et/ou 38, également comme indiqué en trait mixte sur la Figure 1.It should be noted that the invention applies also in the following case: oxygen is produced under 1 bar approximately, and the oxygen demand is still greater than a given minimum value. A flow constant gaseous oxygen equal to this minimum value can then be drawn directly from the bottom of the column low pressure 7 via a pipe 35, as indicated in dashed line in Figure 1, then reheated in the line exchange. This variant reduces the capacity tanks 10 and 11. Likewise, production constants of liquid oxygen and / or nitrogen gas and / or liquid nitrogen can be supplied simultaneously by the double column, via lines 36 and / or 37 and / or 38, also as shown in phantom in Figure 1.

    D'autres variantes de l'invention peuvent être envisagées.Other variants of the invention may be considered.

    Ainsi, dans la variante de la Figure 3, la pompe 13 est supprimée. Le débit auxiliaire d'oxygène est soutiré sous forme gazeuse de la cuve de la colonne 7, via une conduite 39, est réchauffé en 30 sous la basse pression, puis est comprimé à la haute pression par un compresseur auxiliaire 40 avant d'être introduit dans la capacité 15.Thus, in the variant of Figure 3, the pump 13 is deleted. The auxiliary oxygen flow is withdrawn in gaseous form from the tank of column 7, via a pipe 39, is heated at 30 below the low pressure and then is compressed at high pressure by a auxiliary compressor 40 before being introduced into the capacity 15.

    En variante également, le fluide de vaporisation d'au moins l'un des deux débits d'oxygène est de l'azote. En particulier, dans la variante de la Figure 4, où la production d'oxygène est au voisinage de 1 bar, la vaporisation du débit principal s'effectue au moyen du vaporiseur 8 de la double colonne. Ce débit principal est alors soutiré sous forme gazeuse de la cuve de la colonne 7, via une conduite 41, et réchauffé en 29. Le refoulement de la pompe 12 est alors relié à la cuve de la colonne, laquelle alimente le réservoir 10 par gravité.Alternatively also, the vaporizing fluid at least one of the two oxygen flow rates is nitrogen. In particular, in the variant of Figure 4, where the oxygen production is around 1 bar, the main flow is sprayed using the vaporizer 8 of the double column. This main flow is then withdrawn in gaseous form from the column tank 7, via a pipe 41, and heated at 29. The discharge pump 12 is then connected to the column tank, which feeds the tank 10 by gravity.

    Dans ce cas, la vaporisation du débit variable d'oxygène produit un débit variable d'azote liquide dans la colonne 6. Pour cette raison, la conduite 38 est reliée à un réservoir 42 d'azote, et le fond de ce réservoir est relié à une pompe 43 de retour d'un débit constant d'azote liquide en tête de la colonne 6.In this case, spraying the variable flow of oxygen produces a variable flow of liquid nitrogen in column 6. For this reason, line 38 is connected to a nitrogen tank 42, and the bottom of this tank is connected to a pump 43 for returning a constant flow of nitrogen liquid at the top of column 6.

    La bascule est, dans cette variante, une bascule oxygène/azote, et le réservoir 11, à niveau constant, peut être supprimé.The rocker is, in this variant, a rocker oxygen / nitrogen, and the reservoir 11, at constant level, can be deleted.

    Si l'on combine les variantes des Figures 3 et 4, il n'y a plus d'oxygène à vaporiser dans la ligne d'échange 3. Par suite, les éléments 14, 22, 23, 11, 24 et 25 sont supprimés, et tout l'air entrant est comprimé à 6 bars en 1 et envoyé dans les passages 19.If we combine the variants of Figures 3 and 4, there is no more oxygen to vaporize in the line exchange 3. As a result, elements 14, 22, 23, 11, 24 and 25 are removed, and all incoming air is compressed to 6 bars in 1 and sent in passages 19.

    Claims (16)

    1. Process for producing a gas, in particular oxygen, from air at a variable flow rate by air distillation, of the type in which at least some of the gas to be produced is stored, in the form of a first liquid, in a first storage tank (10); a variable flow of the said first liquid is drawn off from this storage tank and conveyed (in 12, 29; 12, 8, 29) in gaseous form at the production pressure, this variable flow being vaporized (in 29; 8) by condensing a corresponding variable flow of a second fluid, in particular air to be distilled; this condensed second fluid is stored, in the form of a second liquid, in a second storage tank (11); and a controlled flow of this second liquid is sent to the distillation unit, characterized in that an auxiliary flow of the gas to be produced is conveyed in gaseous form at a high pressure greater than the production pressure and then stored in an auxiliary tank (15) under the said high pressure, and, during certain peaks in demand of the said gas, at least some of the excess gas is bled off from this auxiliary tank, after having expanded it (in 34) to the production pressure.
    2. Process according to Claim 1, characterized in that the said auxiliary flow, in liquid form, is compressed (in 13) to the said high pressure and the compressed auxiliary flow is vaporized at this high pressure before letting it into the auxiliary tank (15).
    3. Process according to Claim 2, characterized in that the said compressed auxiliary flow is vaporized by heat exchange with the said second fluid.
    4. Process according to Claim 3, characterized in that the said variable flow and the said auxiliary flow are vaporized by heat exchange with the said second fluid at a single condensation pressure.
    5. Process according to Claim 3 or 4, characterized in that the said single condensation pressure is such that the condensation temperature of the second fluid is less than the vaporization temperature of the said gas, at least at the said high pressure.
    6. Process according to Claim 5, characterized in that the condensation temperature of the said second fluid at the said condensation pressure is concomitant with the vaporization temperature of the said gas at the production pressure.
    7. Process according to any one of Claims 1 to 6, characterized in that a constant flow of the said first liquid is drawn off from the distillation unit (5) and in that a constant flow of the said second liquid is sent from the second storage tank (11) to the distillation unit.
    8. Process according to any one of Claims 1 to 7, characterized in that the auxiliary flow represents a minor fraction of the flow of the said first liquid, in particular approximately 25% of the latter, under nominal running conditions.
    9. Process according to any one of Claims 1 to 8, characterized in that the said auxiliary flow has a constant flow rate.
    10. Process according to any one of Claims 1 to 9, characterized in that the said peaks in demand are peaks having an amplitude greater than a predetermined value.
    11. Process according to any one of Claims 1 to 10, characterized in that, up to a predetermined excess flow rate of the said gas, this excess flow rate is achieved by increasing the said variable flow rate.
    12. Plant for producing a gas, in particular oxygen, from air at a variable flow rate, of the type comprising: an air distillation unit (5); a heat-exchanger (3) for cooling the air to be distilled by heat exchange with products coming from the distillation unit; a first storage tank (10) for storing the said gas in the form of a first liquid; first means (12, 29; 12, 8, 29) for drawing off a variable flow of the said first liquid from the first storage tank and conveying it in gaseous form at the production pressure, these first means comprising second means (29; 8) for vaporizing the said variable flow by condensing a corresponding variable flow of a second fluid, in particular air to be distilled, in the form of a second liquid; and a second storage tank (11) for storing the second liquid, characterized in that it comprises third means (13, 30) for conveying an auxiliary flow of the gas to be produced in gaseous form at a high pressure, greater than the production pressure, and then letting it into an auxiliary tank (15), and a line (33) provided with an expansion and flow-regulating valve (34) and connecting this auxiliary tank to the production line (16) of the plant.
    13. Plant according to Claim 12, characterized in that the said third means (13, 30) comprise a pump (13) for compressing the said auxiliary flow in liquid form and means (30) for vaporizing this compressed auxiliary flow.
    14. Plant according to Claim 13, characterized in that the said pump (13) is connected to the said first storage tank (10).
    15. Plant according to Claim 13 or 14, characterized in that it comprises a single booster (14) conveying the said second fluid at a single condensation pressure by heat exchange with the said variable flow and with the said auxiliary flow.
    16. Plant according to any one of Claims 12 to 15, characterized in that it comprises drawing-off means (28) designed to draw off a constant flow of the said first liquid from the distillation unit (5) and means for sending a constant flow of the said second liquid from the second storage tank (11) to the distillation unit.
    EP97935636A 1996-07-25 1997-07-25 Method and plant for producing an air gas with a variable flow rate Expired - Lifetime EP0914584B1 (en)

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    FR9609376A FR2751737B1 (en) 1996-07-25 1996-07-25 METHOD AND INSTALLATION FOR PRODUCING A VARIABLE FLOW AIR GAS
    PCT/FR1997/001401 WO1998004877A1 (en) 1996-07-25 1997-07-25 Method and plant for producing an air gas with a variable flow rate

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    US6182471B1 (en) * 1999-06-28 2001-02-06 Praxair Technology, Inc. Cryogenic rectification system for producing oxygen product at a non-constant rate
    US6354105B1 (en) * 1999-12-03 2002-03-12 Ipsi L.L.C. Split feed compression process for high recovery of ethane and heavier components
    EP1318368A1 (en) * 2001-12-10 2003-06-11 The Boc Group, Inc. Air separation method to produce gaseous product at a variable flow rate
    GB0219415D0 (en) * 2002-08-20 2002-09-25 Air Prod & Chem Process and apparatus for cryogenic separation process
    US7228715B2 (en) * 2003-12-23 2007-06-12 L'air Liquide, Societe Anonyme A Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation Des Procedes Georges Claude Cryogenic air separation process and apparatus
    US7272954B2 (en) * 2004-07-14 2007-09-25 L'air Liquide, Societe Anonyme A Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation Des Proceded Georges Claude Low temperature air separation process for producing pressurized gaseous product
    US7553419B2 (en) * 2006-05-03 2009-06-30 Organix, Inc. Method of material processing to produce a fiber product
    FR2949845B1 (en) * 2009-09-09 2011-12-02 Air Liquide METHOD FOR OPERATING AT LEAST ONE AIR SEPARATION APPARATUS AND A COMBUSTION UNIT OF CARBON FUELS
    WO2012004241A2 (en) * 2010-07-05 2012-01-12 L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Apparatus and process for the separation of air by cryogenic distillation
    CN103080678B (en) * 2010-09-09 2015-08-12 乔治洛德方法研究和开发液化空气有限公司 For the method and apparatus by separating air by cryogenic distillation
    US10359231B2 (en) * 2017-04-12 2019-07-23 Praxair Technology, Inc. Method for controlling production of high pressure gaseous oxygen in an air separation unit

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    FR2652887B1 (en) * 1989-10-09 1993-12-24 Air Liquide PROCESS AND PLANT FOR THE PRODUCTION OF VARIABLE FLOW GAS OXYGEN BY AIR DISTILLATION.
    FR2670278B1 (en) * 1990-12-06 1993-01-22 Air Liquide METHOD AND INSTALLATION FOR AIR DISTILLATION IN A VARIABLE REGIME FOR THE PRODUCTION OF GASEOUS OXYGEN.
    FR2723184B1 (en) * 1994-07-29 1996-09-06 Grenier Maurice PROCESS AND PLANT FOR THE PRODUCTION OF GAS OXYGEN UNDER PRESSURE WITH VARIABLE FLOW RATE
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