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EP0718576A1 - Process for separating a gaseous mixture by cryogenic distillation - Google Patents

Process for separating a gaseous mixture by cryogenic distillation Download PDF

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Publication number
EP0718576A1
EP0718576A1 EP95402924A EP95402924A EP0718576A1 EP 0718576 A1 EP0718576 A1 EP 0718576A1 EP 95402924 A EP95402924 A EP 95402924A EP 95402924 A EP95402924 A EP 95402924A EP 0718576 A1 EP0718576 A1 EP 0718576A1
Authority
EP
European Patent Office
Prior art keywords
refrigerant
gas mixture
flow
column
distillation column
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.)
Granted
Application number
EP95402924A
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German (de)
French (fr)
Other versions
EP0718576B1 (en
Inventor
Philippe Fraysse
Mike De L'isle
Daniel Rousseau
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.)
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Publication of EP0718576A1 publication Critical patent/EP0718576A1/en
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Publication of EP0718576B1 publication Critical patent/EP0718576B1/en
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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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04157—Afterstage cooling and so-called "pre-cooling" of the feed air upstream the air purification unit and main heat exchange line
    • 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
    • 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
    • F25J3/04254—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using the cold stored in external cryogenic fluids
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04339—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of air
    • F25J3/04345—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of air and comprising a gas work expansion loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04351—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
    • F25J3/04357—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen and comprising a gas work expansion loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/044—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 single pressure main column system only
    • 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
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04787—Heat exchange, e.g. main heat exchange line; Subcooler, external reboiler-condenser
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/72—Refluxing the column with at least a part of the totally condensed overhead gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/42—Nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/40—Processes or apparatus involving steps for recycling of process streams the recycled stream being 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen

Definitions

  • Climatic conditions are important in the design of air separation devices and, more generally, in cryogenic devices. More particularly, the cooling water of the refrigerants of the various stages of compression of the air compressor can vary according to the climate and even between day and night, significantly in certain countries, so that one can record in these countries have temperature fluctuations on the water of around 15 ° C.
  • the refrigeration unit has the disadvantage of being an expensive investment and of using at least one rotating machine, which is unreliable and consumes energy.
  • US-A-4,375,367 describes a system in which a flow of air to be distilled is cooled before being purified by recycling the air produced by the purification system.
  • a refrigeration unit is essential in this case.
  • EP-A-0.624.765A discloses a system which makes it possible to replace the refrigeration unit with a heat exchange system with a pressurized fluid flow coming from the air separation installation. The use of a cycle fluid to cool the air upstream of the purification system is not described.
  • J-A-54103777 describes the use of a nitrogen flow coming from a distillation column to cool the air to be purified.
  • EP-A-0.505.812 discloses that a flow of air to be purified can be cooled with a flow of purified air, before the expansion thereof.
  • the subject of the invention is a method as described above, characterized in that liquid is produced as final product and at least part of the refrigerant is expanded in an expansion machine before it heat exchange with the unpurified gas mixture.
  • the proposed solution applies to all devices for distilling a gaseous mixture containing oxygen and nitrogen and which, for this, use a refrigeration cycle, for example a gaseous or nitrogen mixture. It is well suited to liquid production devices.
  • the invention applies in particular to small liquid production devices by air distillation which use a nitrogen cycle capable of supplying the air with the necessary supplement of frigories for its refrigeration up to its purification temperature.
  • the invention may consist in installing at the outlet of the final refrigerant of the air compressor an auxiliary exchanger allowing, for example, the heat exchange between the compressed air with a fraction of cycle nitrogen taken at an intermediate level of a main exchanger.
  • the compressed air is thus cooled by the cycle nitrogen which is heated in this auxiliary exchanger, then re-mixed with the rest of the cycle nitrogen which has continued to heat in the main exchanger.
  • the subject of the invention is also an installation for separating a gaseous mixture containing nitrogen and oxygen by cryogenic distillation comprising a compressor, a purification system, a main exchanger, at least one distillation column, means constituting a refrigeration system and an auxiliary exchanger which puts the gas mixture compressed by the compressor in heat exchange relation with a refrigerant coming either from the column or from the supply downstream of the purification system, characterized in that it comprises means for drawing off a liquid product and a machine for expansion to relax at least part of the refrigerant upstream of the auxiliary exchanger.
  • an air flow is compressed to 6 X 10 5 Pa by a compressor 1 and cooled to 40 ° C in a water cooler 3. Then the flow enters the auxiliary exchanger 5 where it cools to 25 ° C by heat exchange with a nitrogen flow rate of 6 X 10 5 Pa.
  • Separator pots (not shown) at the outlet of the refrigerant 3 and of the exchanger 5 allow remove the condensed water from the treated air after cooling.
  • the air is cooled in the main exchanger 9 near its dew point, then sent to a double tank conventional column 11 in which the air is separated into liquid oxygen, residual nitrogen at the pressure of the low pressure column (1.3 ⁇ 10 5 Pa) and gaseous and liquid nitrogen substantially pure at the pressure of the medium pressure column (6 ⁇ 10 5 Pa).
  • the flow rate of substantially pure nitrogen gas is heated in the main exchanger 9 to a temperature of 22 ° C., from which the first flow rate 13A of pure nitrogen is withdrawn by the withdrawal valve 15 before passing into the auxiliary exchanger 5 where it cools the supply air to 25 ° C.
  • the nitrogen of cycle 13A is thus heated to 37 ° C.
  • a second flow of pure gaseous nitrogen 13B continues to heat up in the main exchanger 9 to 35 ° C. and joins the first flow 13A after it has passed through the auxiliary exchanger 5.
  • the combined flows are recompressed to 42 bar in the compressor 21 and cooled in the main exchanger 9.
  • a third flow 13C of pure recompressed nitrogen is expanded in the turbine 23 of 42X 10 5 Pa up to 6 X 10 5 Pa and recycled with the nitrogen gas withdrawn from the column at 6X 10 5 Pa.
  • the compressor 21 is coupled to the turbine 23.
  • the residual nitrogen heats up in the main exchanger 9, is further heated in the electric heater 8 and is used to regenerate one of the beds of adsorbent he 7.
  • the cycle flow withdrawn from the main line 9 can be regulated at an intermediate temperature by slaving the withdrawal valve 15 to the temperature of the air leaving the auxiliary exchanger 5.
  • the water temperature can reach 20-22 ° C. Under these conditions, the compressed air will leave the final refrigerant of the compressor 1 at a temperature in the region of 25 ° C and the valve 15 will be closed.
  • the water temperature can reach 30-32 ° C and the air leaving the final refrigerant of compressor 1 will be at a temperature close to 40 ° C.
  • the cycle nitrogen 13A will then be sent at a sufficient flow rate by sufficient opening of the valve 15 so that the temperature of the air leaving the auxiliary exchanger 5 is close to 25 ° C.
  • the system does not have any refrigeration unit, all the cooling power being supplied by the nitrogen cycle.
  • the system in Figure 2 differs from that in Figure 1 in that the nitrogen cycle is replaced by an air cycle (the gas mixture to be distilled).
  • the equipment remains essentially the same.
  • the air flow is compressed in the compressor 17 to 30 X 10 5 Pa, cooled in the exchanger 19 and recompressed by the compressor 21 to 42 X 10 5 Pa. Then, the air cools in the main exchanger 9.
  • An air flow 13C is drawn off after being partially cooled, the remaining part of the air being therefore liquefied and sent to column 11.
  • the flow rate 13C is expanded to 6 X 10 5 Pa in the turbine 23. A portion of this expanded air is sent to column 11 as a gas supply and the rest of the air is heated in the exchanger 9.
  • a flow 13A of this air is partially heated, withdrawn by the valve 15 and sent to the auxiliary exchanger 5 where it cools all the supply air to 25 ° C.
  • the flow 13A then joins the air to be compressed in the compressor 17.
  • the air flow 13B continues to heat up and joins the supply air downstream of the purification system 7.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

O and N are sepd. from air by cryogenic distn. in a double column (II), the incoming air from compressor (1) being precooled by heat exchange (3) with water and then by heat exchange (5) with cool gas before passing via CO2 absorbers (7) and main heat exchanger (9) to column (11). Valve (15) controls the flow of gas (13 A) to heat exchanger (5), which is used only when the temp. of water in heat exchanger (3) is too high to cool the air sufficiently on its own e.g. in summer. The gas (13 A) may be fairly pure N drawn from column (11), or recycled air. Claims are directed to process and appts.

Description

La présente invention est relative à un procédé de séparation d'un mélange gazeux contenant de l'oxygène et de l'azote par distillation dans un appareil cryogénique. En particulier, elle est relative aux procédés du type comprenant les étapes de :

  • comprimer le mélange gazeux ;
  • épurer le mélange gazeux comprimé en eau et en dioxyde de carbone ;
  • refroidir le mélange gazeux épuré au voisinage de sa température de rosée ;
  • distiller le mélange gazeux refroidi dans au moins une colonne de distillation ; et
  • fournir la puissance frigorifique de l'appareil par un système de réfrigération autre qu'un groupe frigorifique, dans lequel on refroidit au moins une partie du mélange gazeux entre les étapes de compression et d'épuration par échange de chaleur indirect avec un débit de fluide frigorigène qui est un produit de la colonne de distillation ou qui constitue une partie du mélange gazeux à distiller.
The present invention relates to a process for the separation of a gaseous mixture containing oxygen and nitrogen by distillation in a cryogenic apparatus. In particular, it relates to processes of the type comprising the steps of:
  • compress the gas mixture;
  • purifying the compressed gas mixture with water and carbon dioxide;
  • cooling the purified gas mixture in the vicinity of its dew point temperature;
  • distilling the cooled gas mixture in at least one distillation column; and
  • supply the refrigerating power of the appliance by a refrigeration system other than a refrigerating unit, in which at least part of the gas mixture is cooled between the compression and purification stages by indirect heat exchange with a flow of fluid refrigerant which is a product of the distillation column or which constitutes part of the gas mixture to be distilled.

Les conditions climatiques sont importantes dans la conception des appareils de séparation d'air et, plus généralement, dans les appareils cryogéniques. Plus particulièrement, l'eau de refroidissement des réfrigérants des différentes étapes de compression du compresseur d'air peut varier selon le climat et même entre le jour et la nuit, de manière importante dans certains pays, de sorte que l'on peut enregistrer dans ces pays des fluctuations de température sur l'eau de l'ordre de 15°C.Climatic conditions are important in the design of air separation devices and, more generally, in cryogenic devices. More particularly, the cooling water of the refrigerants of the various stages of compression of the air compressor can vary according to the climate and even between day and night, significantly in certain countries, so that one can record in these countries have temperature fluctuations on the water of around 15 ° C.

Ces variations sont résolues actuellement par l'installation en sortie du réfrigérant final, d'un groupe frigorifique fournissant l'appoint de frigories que l'eau n'a pas été capable de donner.These variations are currently resolved by the installation at the outlet of the final refrigerant, of a refrigeration unit supplying additional refrigerants that the water has not been able to give.

Le groupe frigorifique présente l'inconvénient d'être d'un investissement coûteux et d'utiliser au moins une machine tournante, qui est peu fiable et consommatrice d'énergie.The refrigeration unit has the disadvantage of being an expensive investment and of using at least one rotating machine, which is unreliable and consumes energy.

US-A-4.375.367 décrit un système dans lequel un débit d'air à distiller est refroidi avant d'être épuré par recyclage de l'air produit par le système d'épuration. Néanmoins, l'usage d'un groupe frigorifique est indispensable dans ce cas.US-A-4,375,367 describes a system in which a flow of air to be distilled is cooled before being purified by recycling the air produced by the purification system. However, the use of a refrigeration unit is essential in this case.

EP-A-0.624.765A divulgue un système qui permet de substituer le groupe frigorifique par un système d'échange de chaleur avec un débit de fluide sous pression provenant de l'installation de séparation d'air. L'usage d'un fluide de cycle pour refroidir l'air en amont du système d'épuration n'est pas décrit.EP-A-0.624.765A discloses a system which makes it possible to replace the refrigeration unit with a heat exchange system with a pressurized fluid flow coming from the air separation installation. The use of a cycle fluid to cool the air upstream of the purification system is not described.

Cette demande de brevet ne divulgue pas non plus une installation dans laquelle l'air est prérefroidi dans un échangeur auxiliaire avec un seul autre fluide.This patent application also does not disclose an installation in which the air is precooled in an auxiliary exchanger with only one other fluid.

J-A-54103777 décrit l'usage d'un débit d'azote provenant une colonne de distillation pour refroidir l'air à épurer.J-A-54103777 describes the use of a nitrogen flow coming from a distillation column to cool the air to be purified.

EP-A-0.505.812 divulgue qu'un débit d'air à épurer peut être refroidi avec un débit d'air épuré, avant la détente de celui-ci.EP-A-0.505.812 discloses that a flow of air to be purified can be cooled with a flow of purified air, before the expansion thereof.

Le but de l'invention est de fournir une solution capable de remédier à ces inconvénients, c'est-à-dire :

  • fournir un appoint de frigories moins coûteux en investissement et en énergie et de permettre une réfrigération de l'air à température constante (environ 25°C) avant son épuration par adsorption.
The object of the invention is to provide a solution capable of remedying these drawbacks, that is to say:
  • to provide additional refrigeration which is less costly in terms of investment and energy and to allow air cooling at constant temperature (around 25 ° C) before it is purified by adsorption.

A cet effet, l'invention a pour objet un procédé comme décrit ci-dessus, caractérisé en ce que l'on produit du liquide comme produit final et on détend au moins une partie du fluide frigorigène dans une machine de détente avant qu'il échange de la chaleur avec le mélange gazeux non épuré.To this end, the subject of the invention is a method as described above, characterized in that liquid is produced as final product and at least part of the refrigerant is expanded in an expansion machine before it heat exchange with the unpurified gas mixture.

La solution proposée s'applique à tous les appareils de distillation d'un mélange gazeux contenant de l'oxygène et de l'azote et qui, pour cela, utilisent un cycle frigorifique, par exemple un mélange gazeux ou d'azote. Elle est bien adaptée aux appareils de production de liquide.The proposed solution applies to all devices for distilling a gaseous mixture containing oxygen and nitrogen and which, for this, use a refrigeration cycle, for example a gaseous or nitrogen mixture. It is well suited to liquid production devices.

L'invention s'applique en particulier aux petits appareils de production de liquide par distillation d'air qui utilisent un cycle azote capable de fournir à l'air l'appoint nécessaire en frigories pour sa réfrigération jusqu'à sa température d'épuration.The invention applies in particular to small liquid production devices by air distillation which use a nitrogen cycle capable of supplying the air with the necessary supplement of frigories for its refrigeration up to its purification temperature.

L'invention peut consister à installer en sortie du réfrigérant final du compresseur d'air un échangeur auxiliaire permettant, par exemple, l'échange thermique entre l'air comprimé avec une fraction d'azote de cycle pris à un niveau intermédiaire d'un échangeur principal. L'air comprimé est ainsi refroidi par l'azote de cycle qui est réchauffé dans cet échangeur auxiliaire, puis remélangé au reste de l'azote de cycle ayant poursuivi son réchauffement dans l'échangeur principal.The invention may consist in installing at the outlet of the final refrigerant of the air compressor an auxiliary exchanger allowing, for example, the heat exchange between the compressed air with a fraction of cycle nitrogen taken at an intermediate level of a main exchanger. The compressed air is thus cooled by the cycle nitrogen which is heated in this auxiliary exchanger, then re-mixed with the rest of the cycle nitrogen which has continued to heat in the main exchanger.

Si l'on veut maintenir constant l'écart de température au bout chaud de l'échangeur principal et soutirer une fraction d'azote de cycle à un niveau intermédiaire de l'échangeur principal, il faut augmenter le débit du fluide de cycle dans cet échangeur.If you want to keep the temperature difference constant at the hot end of the main exchanger and extract a fraction of cycle nitrogen at an intermediate level of the main exchanger, you must increase the flow rate of the cycle fluid in this exchanger.

Globalement, cette solution apporte un gain en investissement de l'ordre de 1 %.Overall, this solution brings an investment gain of around 1%.

Le procédé peut comporter une ou plusieurs des caractéristiques suivantes :

  • le cycle frigorifique est un cycle d'azote ;
  • le fluide frigorigène avec lequel le mélange gazeux échange de la chaleur est le fluide de cycle ;
  • le débit de fluide frigorigène est réglé pour maintenir constante la température de la partie de mélange gazeux ;
  • on épure le mélange gazeux en eau et en dioxyde de carbone par un système de perméation et/ou d'adsorption ;
  • le débit de fluide est un débit d'azote produit par une colonne moyenne pression d'une double colonne de distillation ;
  • toute la puissance frigorifique de l'appareil est fournie par au moins un cycle frigorifique ;
  • après le refroidissement d'au moins une partie du mélange gazeux, le débit de fluide est liquéfié et injecté dans la colonne de distillation.
The process can include one or more of the following characteristics:
  • the refrigeration cycle is a nitrogen cycle;
  • the refrigerant with which the heat exchange gas mixture is the cycle fluid;
  • the refrigerant flow rate is adjusted to keep the temperature of the gas mixture part constant;
  • the gas mixture is purified of water and carbon dioxide by a permeation and / or adsorption system;
  • the fluid flow is a flow of nitrogen produced by a medium pressure column of a double distillation column;
  • all the cooling capacity of the appliance is supplied by at least one refrigerating cycle;
  • after at least part of the gas mixture has cooled, the fluid flow is liquefied and injected into the distillation column.

L'invention a également pour objet une installation de séparation d'un mélange gazeux contenant de l'azote et de l'oxygène par distillation cryogénique comprenant un compresseur, un système d'épuration, un échangeur principal, au moins une colonne de distillation, des moyens constituant un système de réfrigération et un échangeur auxiliaire qui met le mélange gazeux comprimé par le compresseur en relation d'échange thermique avec un fluide frigorigène provenant soit de la colonne, soit de l'alimentation en aval du système d'épuration, caractérisée en ce qu'elle comprend des moyens de soutirage d'un produit liquide et une machine de détente pour détendre au moins une partie du fluide frigorigène en amont de l'échangeur auxiliaire.The subject of the invention is also an installation for separating a gaseous mixture containing nitrogen and oxygen by cryogenic distillation comprising a compressor, a purification system, a main exchanger, at least one distillation column, means constituting a refrigeration system and an auxiliary exchanger which puts the gas mixture compressed by the compressor in heat exchange relation with a refrigerant coming either from the column or from the supply downstream of the purification system, characterized in that it comprises means for drawing off a liquid product and a machine for expansion to relax at least part of the refrigerant upstream of the auxiliary exchanger.

L'installation peut comporter une ou plusieurs des caractéristiques suivantes :

  • une vanne de réglage pour contrôler la quantité de fluide frigorigène envoyé à l'échangeur auxiliaire ;
  • le fluide frigorigène circule dans le cycle de réfrigération ;
  • le fluide frigorigène est de l'azote gazeux provenant d'une colonne moyenne pression d'une double colonne ;
  • le système d'épuration fonctionne par adsorption et/ou perméation ;
  • des moyens pour liquéfier au moins une partie du fluide frigorigène en aval de l'échangeur auxiliaire et d'envoyer au moins une partie du fluide liquéfié à la colonne de distillation ;
  • au moins un compresseur qui comprime le fluide frigorigène en aval de l'échangeur auxiliaire.
The installation may include one or more of the following characteristics:
  • an adjustment valve to control the amount of refrigerant sent to the auxiliary exchanger;
  • the refrigerant circulates in the refrigeration cycle;
  • the refrigerant is nitrogen gas from a medium pressure column of a double column;
  • the purification system works by adsorption and / or permeation;
  • means for liquefying at least part of the refrigerant downstream of the auxiliary exchanger and sending at least part of the liquefied fluid to the distillation column;
  • at least one compressor which compresses the refrigerant downstream of the auxiliary exchanger.

Un exemple de mise en oeuvre de l'invention va maintenant être décrit en regard des dessins annexés qui représentent schématiquement une installation de distillation d'air conforme à l'invention.An example of implementation of the invention will now be described with reference to the accompanying drawings which schematically represent an air distillation installation according to the invention.

Dans le système de la figure 1, un débit d'air est comprimé à 6 X 105 Pa par un compresseur 1 et refroidi jusqu'à 40°C dans un réfrigérant à l'eau 3. Ensuite, le débit rentre dans l'échangeur auxiliaire 5 où il refroidit jusqu'à 25°C par échange de chaleur avec un débit d'azote à 6 X 105 Pa. Des pots séparateurs (non représentés) en sortie du réfrigérant 3 et de l'échangeur 5 permettent d'évacuer l'eau condensée de l'air traité après refroidissement. Après épuration de l'eau restante et du dioxyde de carbone dans un appareil à plusieurs lits d'adsorbant 7, l'air est refroidi dans l'échangeur principal 9 au voisinage de son point de rosée, puis envoyé en cuve d'une double colonne classique 11 dans laquelle l'air est séparé en oxygène liquide, azote résiduaire à la pression de la colonne basse pression (1,3X 105 Pa) et azote gazeux et liquide sensiblement purs à la pression de la colonne moyenne pression (6X 105 Pa). Le débit d'azote gazeux sensiblement pur est réchauffé dans l'échangeur principal 9 jusqu'à une température de 22°C, d'où on soutire le premier débit 13A d'azote pur par la vanne de soutirage 15 avant de passer dans l'échangeur auxiliaire 5 où il refroidit l'air d'alimentation jusqu'à 25°C. L'azote du cycle 13A est ainsi réchauffé à 37°C. Un deuxième débit d'azote pur gazeux 13B poursuit son réchauffement dans l'échangeur principal 9 jusqu'à 35°C et rejoint le premier débit 13A après son passage dans l'échangeur auxiliaire 5. Après être comprimés à 30 X 105 Pa par le compresseur 17 et refroidis dans l'échangeur 19, les débits réunis sont recomprimés jusqu'à 42 bar dans le compresseur 21 et refroidis dans l'échangeur principal 9. Partiellement réchauffé, un troisième débit 13C d'azote pur recomprimé est détendu dans la turbine 23 de 42X 105 Pa jusqu'à 6 X 105 Pa et recyclé avec l'azote gazeux soutiré de la colonne à 6X 105 Pa. Le débit d'azote pur restant se liquéfie dans l'échangeur 9 et sert de reflux pour la colonne moyenne pression de la double colonne 11. Le compresseur 21 est couplé à la turbine 23. L'azote résiduaire se réchauffe dans l'échangeur principal 9, est encore réchauffé dans le réchauffeur électrique 8 et sert à régénérer un des lits d'adsorbant de l'appareil 7.In the system of Figure 1, an air flow is compressed to 6 X 10 5 Pa by a compressor 1 and cooled to 40 ° C in a water cooler 3. Then the flow enters the auxiliary exchanger 5 where it cools to 25 ° C by heat exchange with a nitrogen flow rate of 6 X 10 5 Pa. Separator pots (not shown) at the outlet of the refrigerant 3 and of the exchanger 5 allow remove the condensed water from the treated air after cooling. After purification of the remaining water and carbon dioxide in a device with several adsorbent beds 7, the air is cooled in the main exchanger 9 near its dew point, then sent to a double tank conventional column 11 in which the air is separated into liquid oxygen, residual nitrogen at the pressure of the low pressure column (1.3 × 10 5 Pa) and gaseous and liquid nitrogen substantially pure at the pressure of the medium pressure column (6 × 10 5 Pa). The flow rate of substantially pure nitrogen gas is heated in the main exchanger 9 to a temperature of 22 ° C., from which the first flow rate 13A of pure nitrogen is withdrawn by the withdrawal valve 15 before passing into the auxiliary exchanger 5 where it cools the supply air to 25 ° C. The nitrogen of cycle 13A is thus heated to 37 ° C. A second flow of pure gaseous nitrogen 13B continues to heat up in the main exchanger 9 to 35 ° C. and joins the first flow 13A after it has passed through the auxiliary exchanger 5. After being compressed to 30 × 10 5 Pa by the compressor 17 and cooled in the exchanger 19, the combined flows are recompressed to 42 bar in the compressor 21 and cooled in the main exchanger 9. Partially heated, a third flow 13C of pure recompressed nitrogen is expanded in the turbine 23 of 42X 10 5 Pa up to 6 X 10 5 Pa and recycled with the nitrogen gas withdrawn from the column at 6X 10 5 Pa. The flow of pure nitrogen remaining liquefies in the exchanger 9 and serves as reflux for the medium pressure column of the double column 11. The compressor 21 is coupled to the turbine 23. The residual nitrogen heats up in the main exchanger 9, is further heated in the electric heater 8 and is used to regenerate one of the beds of adsorbent he 7.

On peut réguler le débit de cycle soutiré de la ligne principale 9 à une température intermédiaire en asservissant la vanne de soutirage 15 à la température de l'air en sortie de l'échangeur auxiliaire 5.The cycle flow withdrawn from the main line 9 can be regulated at an intermediate temperature by slaving the withdrawal valve 15 to the temperature of the air leaving the auxiliary exchanger 5.

En période hivernale, la température de l'eau peut atteindre 20-22°C. Dans ces conditions, l'air comprimé sortira du réfrigérant final du compresseur 1 à une température voisine de 25°C et la vanne 15 sera fermée.In winter, the water temperature can reach 20-22 ° C. Under these conditions, the compressed air will leave the final refrigerant of the compressor 1 at a temperature in the region of 25 ° C and the valve 15 will be closed.

En période estivale, la température de l'eau peut atteindre 30-32°C et l'air en sortie du réfrigérant final du compresseur 1 sera à une température voisine de 40°C.In summer, the water temperature can reach 30-32 ° C and the air leaving the final refrigerant of compressor 1 will be at a temperature close to 40 ° C.

L'azote de cycle 13A sera alors envoyé à un débit suffisant par ouverture suffisante de la vanne 15 pour que la température de l'air en sortie de l'échangeur auxiliaire 5 soit voisine de 25°C.The cycle nitrogen 13A will then be sent at a sufficient flow rate by sufficient opening of the valve 15 so that the temperature of the air leaving the auxiliary exchanger 5 is close to 25 ° C.

Le système ne comporte aucun groupe frigorifique, toute la puissance frigorifique étant fournie par le cycle d'azote.The system does not have any refrigeration unit, all the cooling power being supplied by the nitrogen cycle.

Le système de la figure 2 diffère de celui de la figure 1 en ce que le cycle d'azote est remplacé par un cycle d'air (le mélange gazeux à distiller). L'équipement reste essentiellement le même.The system in Figure 2 differs from that in Figure 1 in that the nitrogen cycle is replaced by an air cycle (the gas mixture to be distilled). The equipment remains essentially the same.

Après épuration, le débit d'air est comprimé dans le compresseur 17 à 30 X 105 Pa, refroidi dans l'échangeur 19 et recomprimé par le compresseur 21 à 42 X 105 Pa. Ensuite, l'air se refroidit dans l'échangeur principal 9. Un débit d'air 13C est soutiré après être partiellement refroidi, la partie restante de l'air étant donc liquéfiée et envoyée à la colonne 11. Le débit 13C est détendu jusqu'à 6 X 105 Pa dans la turbine 23. Une partie de cet air détendu est envoyé à la colonne 11 comme alimentation gazeuse et le reste de l'air est réchauffé dans l'échangeur 9. Un débit 13A de cet air est partiellement réchauffé, soutiré par la vanne 15 et envoyé à l'échangeur auxiliaire 5 où il refroidit tout l'air d'alimentation jusqu'à 25°C. Le débit 13A rejoint ensuite l'air à comprimer dans le compresseur 17. Le débit 13B d'air poursuit son réchauffement et rejoint l'air d'alimentation en aval du système d'épuration 7.After purification, the air flow is compressed in the compressor 17 to 30 X 10 5 Pa, cooled in the exchanger 19 and recompressed by the compressor 21 to 42 X 10 5 Pa. Then, the air cools in the main exchanger 9. An air flow 13C is drawn off after being partially cooled, the remaining part of the air being therefore liquefied and sent to column 11. The flow rate 13C is expanded to 6 X 10 5 Pa in the turbine 23. A portion of this expanded air is sent to column 11 as a gas supply and the rest of the air is heated in the exchanger 9. A flow 13A of this air is partially heated, withdrawn by the valve 15 and sent to the auxiliary exchanger 5 where it cools all the supply air to 25 ° C. The flow 13A then joins the air to be compressed in the compressor 17. The air flow 13B continues to heat up and joins the supply air downstream of the purification system 7.

On note que dans les installations de la figure 2, le groupe frigorifique est remplacé par un autre système de réfrigération moins coûteux et plus facile à entretenir.It should be noted that in the installations in FIG. 2, the refrigeration unit is replaced by another less expensive and easier to maintain refrigeration system.

Claims (21)

Procédé de séparation d'un mélange gazeux contenant de l'azote et de l'oxygène par distillation dans un appareil cryogénique comprenant les étapes de : - comprimer le mélange gazeux ; - épurer le mélange gazeux comprimé en eau et en dioxyde de carbone ; - refroidir le mélange gazeux épuré au voisinage de sa température de rosée ; - distiller le mélange gazeux refroidi dans au moins une colonne de distillation (11) ; et - fournir la puissance frigorifique de l'appareil par un système de réfrigération autre qu'un groupe frigorifique, dans lequel on refroidit au moins une partie du mélange gazeux entre les étapes de compression et d'épuration par échange de chaleur indirect avec un débit (13B) de fluide frigorigène qui est un produit de la colonne de distillation ou qui constitue une partie du mélange gazeux à distiller, caractérisé en ce que l'on produit du liquide comme produit final et on détend au moins une partie du fluide frigorigène dans une machine de détente avant qu'il échange de la chaleur avec le mélange gazeux non épuré. Process for the separation of a gaseous mixture containing nitrogen and oxygen by distillation in a cryogenic apparatus comprising the steps of: - compress the gas mixture; - purify the compressed gas mixture with water and carbon dioxide; - cooling the purified gas mixture near its dew point temperature; - distilling the cooled gas mixture in at least one distillation column (11); and - supply the refrigerating power of the appliance by a refrigeration system other than a refrigerating unit, in which at least part of the gas mixture is cooled between the compression and purification stages by indirect heat exchange with a flow rate ( 13B) of refrigerant which is a product of the distillation column or which constitutes part of the gas mixture to be distilled, characterized in that liquid is produced as final product and at least part of the refrigerant is expanded in a expansion machine before it exchanges heat with the unpurified gas mixture. Procédé selon la revendication 1 dans lequel le système de réfrigération est un cycle frigorifique.The method of claim 1 wherein the refrigeration system is a refrigeration cycle. Procédé selon la revendication 2 dans lequel le fluide frigorigène avec lequel le mélange gazeux échange de la chaleur est le fluide de cycle frigorifique.The method of claim 2 wherein the refrigerant with which the heat exchange gas mixture is the refrigerant. Procédé selon la revendication 2 ou 3, dans lequel le système de réfrigération est un cycle d'air ou un cycle d'azote.The method of claim 2 or 3, wherein the refrigeration system is an air cycle or a nitrogen cycle. Procédé selon l'une des revendications précédentes dans lequel le débit (13B) de fluide frigorigène est réglé pour maintenir constante la température de la partie de mélange gazeux.Method according to one of the preceding claims, in which the flow rate (13B) of refrigerant is adjusted to keep the temperature of the part of the gas mixture constant. Procédé selon l'une des revendications précédentes dans lequel on épure le mélange gazeux en eau et en dioxyde de carbone par un système de perméation et/ou d'adsorption (7).Method according to one of the preceding claims, in which the gas mixture is purified of water and carbon dioxide by a permeation and / or adsorption system (7). Procédé selon l'une des revendications précédentes dans lequel le débit (13B) de fluide frigorigène est un débit d'azote produit par une colonne moyenne pression d'une double colonne de distillation (11).Method according to one of the preceding claims, in which the flow (13B) of refrigerant is a flow of nitrogen produced by a medium pressure column of a double distillation column (11). Procédé selon l'une des revendications précédentes dans lequel au moins une partie du mélange gazeux ou du débit de fluide frigorigène est liquéfié et injecté dans la colonne de distillation (11).Method according to one of the preceding claims, in which at least part of the gas mixture or of the flow of refrigerant is liquefied and injected into the distillation column (11). Procédé selon l'une des revendications précédentes dans lequel le système de réfrigération comprend l'injection d'un débit de liquide froid provenant d'une source extérieure dans la colonne de distillation (11).Method according to one of the preceding claims, in which the refrigeration system comprises injecting a flow of cold liquid from an external source into the distillation column (11). Procédé selon l'une des revendications précédentes, dans lequel au moins une partie du fluide frigorigène est surpressé avant d'être détendu.Method according to one of the preceding claims, in which at least part of the refrigerant is overpressed before being expanded. Procédé selon l'une des revendications précédentes, dans lequel le fluide frigorigène est partiellement réchauffé contre le mélange gazeux épuré après sa détente.Method according to one of the preceding claims, in which the refrigerant is partially reheated against the purified gas mixture after its expansion. Installation de séparation d'un mélange gazeux contenant de l'azote et de l'oxygène par distillation cryogénique comprenant un compresseur (1), un système d'épuration (7), un échangeur principal (9), au moins une colonne de distillation (11), des moyens (17, 21, 23) constituant un système de réfrigération et un échangeur auxiliaire (5) qui met le mélange gazeux comprimé par le compresseur (1) en relation d'échange thermique avec un fluide frigorigène provenant soit de la colonne (11), soit de l'alimentation en aval du système d'épuration (7), caractérisée en ce qu'elle comprend des moyens de soutirage d'un produit liquide et une machine de détente (23) pour détendre au moins une partie du fluide frigorigène en amont de l'échangeur auxiliaire.Installation for separating a gaseous mixture containing nitrogen and oxygen by cryogenic distillation comprising a compressor (1), a purification system (7), a main exchanger (9), at least one distillation column (11), means (17, 21, 23) constituting a refrigeration system and an auxiliary exchanger (5) which puts the gas mixture compressed by the compressor (1) in heat exchange relation with a refrigerant coming either from the column (11), either from the supply downstream of the purification system (7), characterized in that it comprises means for withdrawing a liquid product and an expansion machine (23) for at least relaxing part of the refrigerant upstream of the auxiliary exchanger. Installation selon la revendication 12, dans laquelle une vanne de réglage (15) contrôle la quantité de fluide frigorigène envoyé à l'échangeur auxiliaire (5).Installation according to claim 12, in which an adjustment valve (15) controls the quantity of refrigerant sent to the auxiliary exchanger (5). Installation selon la revendication 12 ou 13, dans laquelle le fluide frigorigène circule dans le cycle de réfrigération.Installation according to claim 12 or 13, in which the refrigerant circulates in the refrigeration cycle. Installation selon l'une des revendications 12 à 14, dans laquelle le fluide frigorigène est de l'azote gazeux provenant d'une colonne moyenne pression d'une double colonne (11) ou une partie du mélange gazeux.Installation according to one of claims 12 to 14, wherein the refrigerant is nitrogen gas from a medium pressure column of a double column (11) or part of the gas mixture. Installation selon l'une des revendications 12 à 15, dans laquelle le système d'épuration (7) fonctionne par adsorption et/ou perméation.Installation according to one of claims 12 to 15, in which the purification system (7) operates by adsorption and / or permeation. Installation selon l'une des revendications 12 à 16 comprenant des moyens (17, 19, 21) pour liquéfier le fluide frigorigène en aval de l'échangeur auxiliaire (5) et d'en envoyer au moins une partie à la colonne de distillation (11).Installation according to one of claims 12 to 16 comprising means (17, 19, 21) for liquefying the refrigerant downstream of the auxiliary exchanger (5) and sending at least part of it to the distillation column ( 11). Installation selon l'une des revendications 12 à 17 comprenant au moins un compresseur (17, 21) qui comprime le fluide frigorigène en aval de l'échangeur auxiliaire (5).Installation according to one of claims 12 to 17 comprising at least one compressor (17, 21) which compresses the refrigerant downstream of the auxiliary exchanger (5). Installation selon l'une des revendications 12 à 18 comprenant des moyens pour injecter un débit de liquide provenant d'une source extérieure dans la colonne de distillation (11).Installation according to one of claims 12 to 18 comprising means for injecting a flow of liquid from an external source into the distillation column (11). Installation selon l'une des revendications 12 à 19 dans laquelle l'échangeur auxiliaire (5) met le mélange gazeux en relation d'échange thermique avec un seul fluide frigorigène.Installation according to one of claims 12 to 19 wherein the auxiliary exchanger (5) puts the gas mixture in heat exchange relationship with a single refrigerant. Installation selon l'une des revendications 12 à 20 comprenant des moyens (17, 21) pour surpresser la partie du fluide frigorigène destiné à être détendu.Installation according to one of claims 12 to 20 comprising means (17, 21) for overpressing the part of the refrigerant intended to be expanded.
EP95402924A 1994-12-23 1995-12-22 Process for separating a gaseous mixture by cryogenic distillation Expired - Lifetime EP0718576B1 (en)

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EP0829691A1 (en) * 1996-09-13 1998-03-18 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process for compressing the feed gas of a separation unit for gas mixtures
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US5921106A (en) * 1996-09-13 1999-07-13 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process for compressing a gas associated with a unit for separating a gas mixture
EP1035391A1 (en) * 1999-03-12 2000-09-13 L'air Liquide Société Anonyme pour l'étude et l'exploitation des procédés Georges Claude Process and apparatus for purification and cryogenic separation of air without precooling
FR2790823A1 (en) * 1999-03-12 2000-09-15 Air Liquide METHOD AND APPARATUS FOR CRYOGENIC AIR PURIFICATION AND SEPARATION WITHOUT PRE-COOLING
CN103438665A (en) * 2013-09-01 2013-12-11 杭州哲达科技股份有限公司 Device and method for lowering comprehensive power unit consumption of air separation unit
CN103438665B (en) * 2013-09-01 2015-06-17 杭州哲达科技股份有限公司 Device and method for lowering comprehensive power unit consumption of air separation unit

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DE69511833T2 (en) 2000-05-18
US5651271A (en) 1997-07-29
DE69511833D1 (en) 1999-10-07
CA2165916A1 (en) 1996-06-24
JPH08254389A (en) 1996-10-01
EP0718576B1 (en) 1999-09-01
ES2138172T3 (en) 2000-01-01
CN1133964A (en) 1996-10-23
FR2728663B1 (en) 1997-01-24

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