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EP0677713B1 - Process and installation for the production of oxygen by distillation of air - Google Patents

Process and installation for the production of oxygen by distillation of air Download PDF

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Publication number
EP0677713B1
EP0677713B1 EP95400752A EP95400752A EP0677713B1 EP 0677713 B1 EP0677713 B1 EP 0677713B1 EP 95400752 A EP95400752 A EP 95400752A EP 95400752 A EP95400752 A EP 95400752A EP 0677713 B1 EP0677713 B1 EP 0677713B1
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EP
European Patent Office
Prior art keywords
column
pressure column
low
argon
air
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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
EP95400752A
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German (de)
French (fr)
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EP0677713A1 (en
Inventor
Yves Koeberle
Philippe Fraysse
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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 EP0677713A1 publication Critical patent/EP0677713A1/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
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04103—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression using solely hydrostatic liquid head
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/04193—Division of the main heat exchange line in consecutive sections having different functions
    • F25J3/04206—Division of the main heat exchange line in consecutive sections having different functions including a so-called "auxiliary vaporiser" for vaporising and producing a gaseous product
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04303—Lachmann expansion, i.e. expanded into oxygen producing or low pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
    • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04642—Recovering noble gases from air
    • F25J3/04648—Recovering noble gases from air argon
    • F25J3/04654—Producing crude argon in a crude argon column
    • F25J3/04666—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system
    • F25J3/04672—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser
    • F25J3/04678—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser cooled by oxygen enriched liquid from high pressure column bottoms
    • 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
    • F25J2200/90—Details relating to column internals, e.g. structured packing, gas or liquid distribution
    • F25J2200/92—Details relating to the feed point
    • 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/58—Argon
    • 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
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/30—External or auxiliary boiler-condenser in general, e.g. without a specified fluid or one fluid is not a primary air component or an intermediate fluid
    • F25J2250/40—One fluid 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
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/30—External or auxiliary boiler-condenser in general, e.g. without a specified fluid or one fluid is not a primary air component or an intermediate fluid
    • F25J2250/50—One fluid being oxygen

Definitions

  • the present invention relates to a method and an installation for oxygen and argon production by air distillation and more particularly to a process and an installation for the production of oxygen under pressure and argon.
  • EP-A-0422974 describes a process for producing oxygen under pressure by cryogenic air distillation in a double column.
  • Oxygen liquid is withdrawn from the tank of the low pressure column 7, as illustrated in Figure 1, and vaporizes in the auxiliary exchanger 9 by heat exchange with a fraction of the supply air.
  • the remaining part of the air feed is divided into two flow rates, one of which goes directly to the column medium pressure 6, via line 14, and the other of which is relaxed in a turbine 4 before being sent to the low pressure column 7.
  • EP-A-0580348 describes a process in which rich liquid is sent from a medium pressure column to a low pressure column in two fractions, one of which vaporizes at the head of an argon column before being injected into the low pressure column.
  • An object of this invention is to improve the argon yields if the installation also includes an argon column supplied by the low pressure column.
  • the subject of the invention is a process for the production of oxygen. gas and argon according to claim 1.
  • the rich medium pressure medium liquid first, second and a third fractions and we send the first and second fractions to different levels in the low pressure column after sub-cooling prior.
  • the third fraction is sent to the head condenser of the argon column. This notably makes it possible to significantly improve the extraction argon.
  • the first and second fractions can be sent to the low pressure column at different temperatures, in order to improve again the reflux in the low pressure column and the argon extraction in the case where the installation also includes an argon column.
  • part of the supply air is expanded before to be sent to the double column, the remaining part of the supply air being partially condensed in the auxiliary exchanger.
  • the temperature difference in the auxiliary exchanger can be reduced to an average value of 0.6 ° C.
  • the invention also relates to a production installation according to claim 6.
  • EP-A-422,974 send some of the condensed air to the medium pressure column, a few trays above the tank so that she can participate in the less weakly, on distillation in this column.
  • the installation represented in FIG. 1 essentially comprises a main air compressor 1 with variable flow, for example of the type centrifugal with movable blades, an air blower with movable blades 2, a heat exchange line 3, a turbine 4 for maintaining cold, a air distillation apparatus 5 consisting of a double column comprising itself a medium pressure column 6 surmounted by a low column pressure 7 and a minaret 7A, a vaporizer-condenser 8, a heat exchanger auxiliary heat 9 and a pump 10.
  • This installation is intended for produce a variable flow of gaseous oxygen via a line 12, under a pressure higher than atmospheric pressure.
  • the first overpressed fraction is cooled to the neighborhood from its dew point in passages of the exchange line then condensed in the auxiliary exchanger 9 and is divided into a first flow constant relaxed under 6 bar sent to the medium pressure column via a pipe 16, and a second constant relaxed flow towards 1 bar in a expansion valve 13 then injected into the low pressure column 7.
  • the vaporizer-condenser 8 vaporizes a constant flow of oxygen liquid in the low pressure column tank by condensation of a flow at about equal to nitrogen at the head of the medium pressure column.
  • Some cash rich "(oxygen-enriched air) taken from the bottom of the middle column pressure and expanded to around 1 bar in an expansion valve 18a is injected at an intermediate level of the low pressure column, and of the "lean liquid” (almost pure nitrogen) taken from the top of the medium pressure column and expanded to around 1 bar in an expansion valve 19 is injected at the top of the low pressure column.
  • Liquid nitrogen is injected at the top of the 7A minaret through the expansion valve 21. Pure nitrogen is withdrawn from the top of the minaret 7A and sent to exchange line 3 to be reheated there before exiting by the line 20. The impure nitrogen leaves via line 25 from the top of the column low pressure 7 and is sent outside via line 18.
  • Liquid oxygen withdrawn from the lower column tank pressure 7 is pumped to production pressure before being sprayed into the auxiliary exchanger 9 (constituted by a “film” type vaporizer) by heat exchange with partially condensed air. Oxygen vaporized comes out, after heating in the exchange line 3, by the driving 12.
  • argon a fraction rich in argon is drawn off from the lower part of the low pressure column 7 and is sent to the column of argon 16 for distillation.
  • This fraction includes mainly argon and oxygen.
  • the tank liquid resulting from the distillation in column 16 is returned to the bottom of the low pressure column 7.
  • the overhead condenser 29 of the argon column 16 is cooled by rich liquid from the medium column tank pressure 6, relieved by valve 23, vaporized and sent to the lower column pressure.
  • valve 18a The remaining part of the rich liquid from the column tank medium pressure 6 is relieved by the valve 18a at a pressure slightly above atmospheric pressure and sent to the bottom column pressure 7 by valve 18, substantially at the same level as the level injection of the air expanded by the turbine 4 (the blowing air).
  • the remaining part of rich liquid not vaporized in 29 is divided into two fractions: one first fraction is injected, as shown in Figure 1, after expansion by valve 18 in the low pressure column 7 at the air blast and the second fraction of rich liquid is sent to the low pressure column 7, after expansion to the pressure thereof by the valve 17, at an intermediate level between the injection level of the first fraction of rich liquid through valve 18a and the level of withdrawal of nitrogen through line 25.
  • the variant of Figure 3 has only one compressor air 1, all the compressed air being sent either to turbine 4 or to exchanger 9.
  • the partially condensed air in exchanger 9 passes entirely in the tank of the medium pressure column 6.
  • the difference in level between the level of liquid oxygen in the BP column tank and its inlet in the fixed vaporizer 9, in this case, the vaporization pressure of oxygen; the pump 10 in Figure 2 is therefore deleted.
  • the fractions of rich liquid can be sub-cooled so that the temperature of the fraction injected at the level of insufflation of air is lower than that of the fraction injected at the level intermediate.
  • This arrangement of the exchanger 9 allows a gain of approximately 6% on the compression of the air and therefore on the specific energy of oxygen product.

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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)
  • Oxygen, Ozone, And Oxides In General (AREA)

Description

La présente invention est relative à un procédé et une installation pour la production de l'oxygène et d'argon par distillation d'air et plus particulièrement à un procédé et une installation pour la production de l'oxygène sous pression et d'argon.The present invention relates to a method and an installation for oxygen and argon production by air distillation and more particularly to a process and an installation for the production of oxygen under pressure and argon.

EP-A-0422974 décrit un procédé de production d'oxygène sous pression par distillation cryogénique d'air dans une double colonne. L'oxygène liquide est soutiré de la cuve de la colonne basse pression 7, comme illustré à la figure 1, et se vaporise dans l'échangeur auxiliaire 9 par échange de chaleur avec une fraction de l'air d'alimentation. La partie restante de l'air d'alimentation est divisée en deux débits, dont l'un va directement à la colonne moyenne pression 6, via la conduite 14, et dont l'autre est détendu dans une turbine 4 avant d'être envoyé à la colonne basse pression 7.EP-A-0422974 describes a process for producing oxygen under pressure by cryogenic air distillation in a double column. Oxygen liquid is withdrawn from the tank of the low pressure column 7, as illustrated in Figure 1, and vaporizes in the auxiliary exchanger 9 by heat exchange with a fraction of the supply air. The remaining part of the air feed is divided into two flow rates, one of which goes directly to the column medium pressure 6, via line 14, and the other of which is relaxed in a turbine 4 before being sent to the low pressure column 7.

EP-A-0580348 décrit un procédé dans lequel du liquide riche est envoyé d'une colonne moyenne pression à une colonne basse pression en deux fractions dont une se vaporise en tête d'une colonne argon avant d'être injectée dans la colonne basse pression.EP-A-0580348 describes a process in which rich liquid is sent from a medium pressure column to a low pressure column in two fractions, one of which vaporizes at the head of an argon column before being injected into the low pressure column.

Un objet de cette invention est d'améliorer les rendements d'argon dans le cas où l'installation comprend également une colonne argon alimentée par la colonne basse pression.An object of this invention is to improve the argon yields if the installation also includes an argon column supplied by the low pressure column.

A cet effet, l'invention a pour objet un procédé de production d'oxygène gazeux et d'argon selon la revendication 1.To this end, the subject of the invention is a process for the production of oxygen. gas and argon according to claim 1.

Afin d'améliorer le reflux de la colonne basse pression, on divise le liquide riche de la colonne moyenne pression en une première, une deuxième et une troisième fractions et on envoie les première et deuxième fractions à des niveaux différents dans la colonne basse pression après sous-refroidissement préalable. La troisième fraction est envoyée au condenseur de tête de la colonne argon. Ceci permet notamment d'améliorer sensiblement l'extraction d'argon.In order to improve the reflux of the low pressure column, the rich medium pressure medium liquid first, second and a third fractions and we send the first and second fractions to different levels in the low pressure column after sub-cooling prior. The third fraction is sent to the head condenser of the argon column. This notably makes it possible to significantly improve the extraction argon.

Les première et deuxième fractions peuvent être envoyées dans la colonne basse pression à des températures différentes, ce afin d'améliorer encore les reflux dans la colonne basse pression et l'extraction d'argon dans le cas où l'installation comprend également une colonne argon.The first and second fractions can be sent to the low pressure column at different temperatures, in order to improve again the reflux in the low pressure column and the argon extraction in the case where the installation also includes an argon column.

De préférence, une partie de l'air d'alimentation est détendue avant d'être envoyée à la double colonne, la partie restante de l'air d'alimentation étant partiellement condensée dans l'échangeur auxiliaire.Preferably, part of the supply air is expanded before to be sent to the double column, the remaining part of the supply air being partially condensed in the auxiliary exchanger.

Quand l'air ne se condense que partiellement dans l'échangeur auxiliaire, l'échange de chaleur avec l'oxygène sous pression s'effectue à une température moyenne plus chaude que s'il se condensait totalement.When the air only partially condenses in the exchanger auxiliary, heat exchange with pressurized oxygen takes place at a average temperature warmer than if it condensed completely.

Pour un même écart de température dans l'échangeur auxiliaire, on peut donc réduire la pression de l'air. En utilisant un vaporiseur à film comme échangeur auxiliaire, tel que décrit en EP-A-0130122, I'écart de température peut être réduit à une valeur moyenne de 0,6 °C.For the same temperature difference in the auxiliary exchanger, we can therefore reduce air pressure. Using a film vaporizer as auxiliary exchanger, as described in EP-A-0130122, the temperature difference can be reduced to an average value of 0.6 ° C.

L'invention a également pour objet une installation de production selon la revendication 6.The invention also relates to a production installation according to claim 6.

L'inconvénient principal des Oxytonnes ® à pompe résulte de la surpression de l'air à sa pression de condensation. Si l'oxygène doit être pompé à des pressions conséquentes telles qu'il soit nécessaire de surpresser l'air à une pression supérieure à celle de la colonne moyenne pression, cette invention ne présente pas d'intérêt puisque l'on dépense globalement plus d'énergie de compression avec cette situation, étant donné que le débit d'air surpressé est approximativement trois fois supérieur à celui du système selon EP-A-0422974, si tout l'air non turbiné passe à l'échangeur auxiliaire.The main drawback of pump Oxytonnes ® results from the air overpressure at its condensing pressure. If oxygen is to be pumped at consequent pressures such that it is necessary to overpress air at a pressure higher than that of the medium pressure column, this invention is of no interest since we generally spend more compression energy with this situation, since the air flow overpressed is approximately three times that of the system according to EP-A-0422974, if all the non-turbinated air passes to the auxiliary exchanger.

Si le reflux de tête de la colonne basse pression est faible, lorsqu'on veut séparer l'argon selon une méthode classique de distillation dans une colonne en parallèle avec la colonne basse pression, ceci conduit à un mauvais rendement en argon. If the head reflux of the low pressure column is low, when wants to separate the argon according to a classic method of distillation in a column in parallel with the low pressure column, this leads to a poor argon yield.

Cette réduction du reflux de tête peut être due à plusieurs facteurs :This reduction in head reflux may be due to several factors:

Si de l'air est condensé dans un vaporiseur d'oxygène, il ne participe pas à la distillation dans la colonne moyenne pression et donc ne participe pas au chauffage dans le vaporiseur principal en cuve de la colonne basse pression. Ainsi, la quantité d'azote liquide pour le reflux de tête de la colonne basse pression est réduite.If air is condensed in an oxygen vaporizer, it will not does not participate in the distillation in the medium pressure column and therefore does not does not participate in heating in the main tank vaporizer of the low pressure column. So the amount of liquid nitrogen for the reflux of low pressure column head is reduced.

Il en est de même si l'air turbiné est envoyé uniquement dans la colonne basse pression, réduisant encore plus le reflux de tête de la colonne basse pression.The same applies if the turbined air is sent only to the low pressure column, further reducing head reflux from the low pressure column.

Pour pallier ces défauts, on proposait dans EP-A-422.974 d'envoyer une partie de l'air condensé dans la colonne moyenne pression, quelques plateaux au-dessus de la cuve pour qu'elle puisse participer, au moins faiblement, à la distillation dans cette colonne.To overcome these shortcomings, it was proposed in EP-A-422,974 send some of the condensed air to the medium pressure column, a few trays above the tank so that she can participate in the less weakly, on distillation in this column.

Or, dans la présente invention, pour compenser les pertes de reflux, due par exemple, au fait que la phase liquide de l'air condensé dans le vaporiseur extérieur se retrouve dans le liquide riche en cuve de la colonne moyenne pression, ce liquide riche est divisé en deux fractions :

  • une première fraction est envoyée dans la colonne basse pression à un premier niveau, habituellement au niveau de l'insufflation d'air dans le cas où il y a une turbine d'insufflation ;
  • une deuxième fraction est envoyée dans la colonne basse pression à un niveau intermédiaire entre le premier niveau et le niveau de soutirage d'azote impur.
However, in the present invention, to compensate for the reflux losses, due for example, to the fact that the liquid phase of the air condensed in the external vaporizer is found in the liquid rich in the bottom of the medium pressure column, this rich liquid is divided into two fractions:
  • a first fraction is sent to the low pressure column at a first level, usually at the level of air insufflation in the case where there is an insufflation turbine;
  • a second fraction is sent to the low pressure column at an intermediate level between the first level and the level of withdrawal of impure nitrogen.

Il est clair que cette disposition des niveaux d'injection peut présenter un intérêt pour des procédés de distillation cryogénique autres que celui décrit dans la présente demande.It is clear that this arrangement of the injection levels can be of interest for other cryogenic distillation processes than that described in this application.

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

  • la figure 1 représente schématiquement un mode de réalisation de l'installation selon l'art antérieur ; et
  • les figures 2 et 3 représentent schématiquement deux modes de réalisation de l'installation conforme à l'invention.
Examples of implementation of the invention and of the prior art will now be described with reference to the accompanying drawings, in which:
  • FIG. 1 schematically represents an embodiment of the installation according to the prior art; and
  • Figures 2 and 3 schematically represent two embodiments of the installation according to the invention.

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 surpresseur d'air à aubages mobiles 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 et un minaret 7A, un vaporiseur-condenseur 8, un échangeur de chaleur auxiliaire 9 et une pompe 10. Cette installation est destinée à produire un débit variable d'oxygène gazeux via une conduite 12, sous une pression supérieure à la pression atmosphérique.The installation represented in FIG. 1 essentially comprises a main air compressor 1 with variable flow, for example of the type centrifugal with movable blades, an air blower with movable blades 2, a heat exchange line 3, a turbine 4 for maintaining cold, a air distillation apparatus 5 consisting of a double column comprising itself a medium pressure column 6 surmounted by a low column pressure 7 and a minaret 7A, a vaporizer-condenser 8, a heat exchanger auxiliary heat 9 and a pump 10. This installation is intended for produce a variable flow of gaseous oxygen via a line 12, under a pressure higher than atmospheric pressure.

Le débit nominal d'air à traiter, comprimé à 6 bar par le compresseur 1, refroidi à la température ambiante et épuré, est divisé en deux fractions. La première fraction est surpressée par le surpresseur 2 et la deuxième fraction passe directement à la ligne d'échange 3 où elle est divisée en deux flux ayant chacun un débit constant :

  • un premier flux est refroidi dans des passages de la ligne d'échange; 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 ; un second flux poursuit son refroidissement jusqu'au voisinage de son point de rosée sous 6 bar, puis est injecté au bas de la colonne moyenne pression 6 via une conduite 14.
The nominal flow of air to be treated, compressed to 6 bar by compressor 1, cooled to room temperature and purified, is divided into two fractions. The first fraction is boosted by the booster 2 and the second fraction goes directly to the exchange line 3 where it is divided into two flows, each having a constant flow:
  • a first flow is cooled in passages of the exchange line; a portion has left this exchange line after partial cooling, expanded to 1 bar in the turbine 4 and blown into the low pressure column 7 near its dew point; a second flow continues to cool down to the vicinity of its dew point under 6 bar, then is injected at the bottom of the medium pressure column 6 via a pipe 14.

La première fraction surpressée est refroidie jusqu'au voisinage de son point de rosée dans des passages de la ligne d'échange puis condensée dans l'échangeur auxiliaire 9 et est divisée en un premier débit constant détendu sous 6 bar envoyé dans la colonne moyenne pression via une conduite 16, et un second débit constant détendu vers 1 bar dans une vanne de détente 13 puis injecté dans la colonne basse pression 7.The first overpressed fraction is cooled to the neighborhood from its dew point in passages of the exchange line then condensed in the auxiliary exchanger 9 and is divided into a first flow constant relaxed under 6 bar sent to the medium pressure column via a pipe 16, and a second constant relaxed flow towards 1 bar in a expansion valve 13 then injected into the low pressure column 7.

Le vaporiseur-condenseur 8 vaporise un débit constant d'oxygène liquide en cuve de la colonne basse pression par condensation d'un débit à peu près égal d'azote de tête de la colonne moyenne pression. 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 18a 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 19 est injecté au sommet de la colonne basse pression.The vaporizer-condenser 8 vaporizes a constant flow of oxygen liquid in the low pressure column tank by condensation of a flow at about equal to nitrogen at the head of the medium pressure column. Some cash rich "(oxygen-enriched air) taken from the bottom of the middle column pressure and expanded to around 1 bar in an expansion valve 18a is injected at an intermediate level of the low pressure column, and of the "lean liquid" (almost pure nitrogen) taken from the top of the medium pressure column and expanded to around 1 bar in an expansion valve 19 is injected at the top of the low pressure column.

De l'azote liquide est injecté au sommet du minaret 7A à travers la vanne de détente 21. De l'azote pur est soutiré du sommet du minaret 7A et envoyé à la ligne d'échange 3 pour y être réchauffé avant de ressortir par la conduite 20. L'azote impur sort par la conduite 25 du sommet de la colonne basse pression 7 et est envoyé à l'extérieur par la conduite 18.Liquid nitrogen is injected at the top of the 7A minaret through the expansion valve 21. Pure nitrogen is withdrawn from the top of the minaret 7A and sent to exchange line 3 to be reheated there before exiting by the line 20. The impure nitrogen leaves via line 25 from the top of the column low pressure 7 and is sent outside via line 18.

L'oxygène liquide soutiré de la cuve de la colonne basse pression 7 est pompé à la pression de production avant d'être vaporisé dans l'échangeur auxiliaire 9 (constitué par un vaporiseur du type "à film") par échange de chaleur avec l'air qui s'y condense partiellement. L'oxygène vaporisé sort, après réchauffement dans la ligne d'échange 3, par la conduite 12.Liquid oxygen withdrawn from the lower column tank pressure 7 is pumped to production pressure before being sprayed into the auxiliary exchanger 9 (constituted by a “film” type vaporizer) by heat exchange with partially condensed air. Oxygen vaporized comes out, after heating in the exchange line 3, by the driving 12.

Pour produire de l'argon, une fraction riche en argon est soutirée de la partie inférieure de la colonne basse pression 7 et est envoyée à la colonne d'argon 16 pour y être distillée. Cette fraction comprend essentiellement de l'argon et de l'oxygène. Le liquide de cuve résultant de la distillation dans la colonne 16 est renvoyée en partie inférieure de la colonne basse pression 7. Le condenseur de tête 29 de la colonne argon 16 est refroidi par du liquide riche provenant de la cuve de la colonne moyenne pression 6, détendu par la vanne 23, vaporisé et envoyé à la colonne basse pression.To produce argon, a fraction rich in argon is drawn off from the lower part of the low pressure column 7 and is sent to the column of argon 16 for distillation. This fraction includes mainly argon and oxygen. The tank liquid resulting from the distillation in column 16 is returned to the bottom of the low pressure column 7. The overhead condenser 29 of the argon column 16 is cooled by rich liquid from the medium column tank pressure 6, relieved by valve 23, vaporized and sent to the lower column pressure.

La partie restante du liquide riche de la cuve de la colonne moyenne pression 6 est détendu par la vanne 18a à une pression légèrement au-dessus de la pression atmosphérique et envoyée dans la colonne basse pression 7 par la vanne 18, sensiblement au même niveau que le niveau d'injection de l'air détendu par la turbine 4 (l'air d'insufflation).The remaining part of the rich liquid from the column tank medium pressure 6 is relieved by the valve 18a at a pressure slightly above atmospheric pressure and sent to the bottom column pressure 7 by valve 18, substantially at the same level as the level injection of the air expanded by the turbine 4 (the blowing air).

L'installation représentée à la figure 2 diffère de l'art antérieur selon la figure 1 par le fait que tout l'air qui n'est pas surpressé par le surpresseur 2 est envoyé à la turbine 4 pour être détendu et envoyé à la colonne basse pression 7. L'air surpressé et partiellement condensé dans l'échangeur 9 auxiliaire est entièrement injecté en cuve de la colonne moyenne pression 6.The installation shown in Figure 2 differs from the prior art according to Figure 1 by the fact that all the air which is not supercharged by booster 2 is sent to the turbine 4 to be expanded and sent to the low pressure column 7. The air overpressed and partially condensed in the auxiliary exchanger 9 is fully injected into the tank of the medium pressure column 6.

Pour améliorer le rendement en argon, la partie restante de liquide riche non vaporisée en 29 est divisée en deux fractions : une première fraction est injectée, comme représenté sur la figure 1, après détente par la vanne 18 dans la colonne basse pression 7 au niveau de l'insufflation d'air et la deuxième fraction de liquide riche est envoyée à la colonne basse pression 7, après détente à la pression de celle-ci par la vanne 17, à un niveau intermédiaire entre le niveau d'injection de la première fraction de liquide riche à travers la vanne 18a et le niveau de soutirage d'azote à travers la conduite 25.To improve the argon yield, the remaining part of rich liquid not vaporized in 29 is divided into two fractions: one first fraction is injected, as shown in Figure 1, after expansion by valve 18 in the low pressure column 7 at the air blast and the second fraction of rich liquid is sent to the low pressure column 7, after expansion to the pressure thereof by the valve 17, at an intermediate level between the injection level of the first fraction of rich liquid through valve 18a and the level of withdrawal of nitrogen through line 25.

Dans le cas où l'oxygène liquide est pressurisé à une pression dite concomitante à la pression de la colonne moyenne pression (c'est-à-dire à environ 2 bar), le système de la figure 2 peut être simplifié.In the case where liquid oxygen is pressurized to a pressure said to be concomitant with the pressure of the medium pressure column (i.e. at around 2 bar), the system in Figure 2 can be simplified.

La variante de la figure 3 ne comporte qu'un seul compresseur d'air 1, tout l'air comprimé étant envoyé soit à la turbine 4, soit à l'échangeur 9. L'air partiellement condensé dans l'échangeur 9 passe entièrement à la cuve de la colonne moyenne pression 6. La dénivellation entre le niveau d'oxygène liquide de la cuve de la colonne BP et son entrée dans le vaporiseur 9 fixe, dans ce cas, la pression de vaporisation de l'oxygène ; la pompe 10 de la figure 2 est donc supprimée.The variant of Figure 3 has only one compressor air 1, all the compressed air being sent either to turbine 4 or to exchanger 9. The partially condensed air in exchanger 9 passes entirely in the tank of the medium pressure column 6. The difference in level between the level of liquid oxygen in the BP column tank and its inlet in the fixed vaporizer 9, in this case, the vaporization pressure of oxygen; the pump 10 in Figure 2 is therefore deleted.

Si besoin est, on peut sous-refroidir les fractions de liquide riche pour que la température de la fraction injectée au niveau de l'insufflation d'air soit moins élevée que celle de la fraction injectée au niveau intermédiaire.If necessary, the fractions of rich liquid can be sub-cooled so that the temperature of the fraction injected at the level of insufflation of air is lower than that of the fraction injected at the level intermediate.

Cette disposition de l'échangeur 9 permet un gain d'environ 6 % sur la compression de l'air et donc sur l'énergie spécifique de l'oxygène produit.This arrangement of the exchanger 9 allows a gain of approximately 6% on the compression of the air and therefore on the specific energy of oxygen product.

Cette disposition des niveaux d'injection du liquide riche permet d'obtenir un gain de production d'argon d'environ 5 %, en comparaison avec celle de EP-A-422.974. Le rendement obtenu avec le procédé de la présente invention est d'environ 80 %.This arrangement of the injection levels of the rich liquid allows to obtain a gain in argon production of around 5%, in comparison with that of EP-A-422,974. The yield obtained with the process of the present invention is around 80%.

Claims (7)

  1. Process for the production of gaseous oxygen under pressure and of argon by cryogenic distillation of air in a double column (5) comprising a medium-pressure column (6) and a low-pressure column (7), in which process the rich liquid coming from the base of the medium-pressure column is divided into first and second liquid fractions that are sent to different levels in the low-pressure column (7), an argon-enriched fluid is withdrawn from the low-pressure column (7) and distilled in an argon column (16), argon is withdrawn from the head of the argon column, an oxygen-enriched liquid is withdrawn from a lower portion of the low-pressure column, pressurized and vaporized by heat exchange with the air intended for the double column (5) in order to form gaseous oxygen under pressure, and a third fraction of rich liquid is sent to the head condenser of the argon column where it vaporizes before being sent to a third level of the low-pressure column (7), the various levels being below a level from which impure nitrogen is withdrawn from the low-pressure column (7).
  2. Process according to Claim 1, in which the first and second fractions are cooled to different temperatures before being sent into the low-pressure column (7).
  3. Process according to either of Claims 1 and 2, in which a portion of the supply air is blown in at an intermediate level of the low-pressure column (7) and the levels at which the first and second fractions of rich liquid are injected are not below this intermediate level.
  4. Process according to Claim 3, in which a fraction of rich liquid is sent to the low-pressure column (7) at approximately the same level as the blown-in air.
  5. Plant for the production of gaseous oxygen under pressure and of argon by cryogenic distillation of air comprising a double column (5), consisting of at least one medium-pressure column (6) surmounted by a low-pressure column (7) and an argon distillation column, means (25) for withdrawing impure nitrogen from the low-pressure column, means (12) for withdrawing an oxygen-enriched liquid from the lower portion of the low-pressure column (7), in order to pressurize (10) and vaporize (9) the said oxygen-enriched liquid against the air intended for the double column so as to form gaseous oxygen under pressure and means for withdrawing argon from the head of the argon distillation column, means for withdrawing rich liquid from the base of the medium-pressure column (6) and sending it to three different levels of the low-pressure column (7), these levels lying below the level from which the impure nitrogen is withdrawn, and pipes for sending the rich liquid to two different levels without passing through the head condenser of the argon distillation column and for sending a third fraction of the rich liquid to the head condenser of the argon distillation column, in order to vaporize it and to send it to the third level of the low-pressure column.
  6. Plant according to Claim 5, comprising means for sending the rich liquid into the low-pressure column (7) at two different temperatures.
  7. Plant according to either of Claims 5 and 6, comprising means (4) for sending air to an intermediate level of the low-pressure column (7) and means for sending the two fractions of rich liquid to levels near or above the intermediate level.
EP95400752A 1994-04-12 1995-04-04 Process and installation for the production of oxygen by distillation of air Expired - Lifetime EP0677713B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9404298A FR2718518B1 (en) 1994-04-12 1994-04-12 Process and installation for the production of oxygen by air distillation.
FR9404298 1994-04-12

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EP0677713A1 EP0677713A1 (en) 1995-10-18
EP0677713B1 true EP0677713B1 (en) 1999-10-20

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GB9910701D0 (en) 1999-05-07 1999-07-07 Boc Group Plc Separation of air
GB9925097D0 (en) * 1999-10-22 1999-12-22 Boc Group Plc Air separation
US6253576B1 (en) * 1999-11-09 2001-07-03 Air Products And Chemicals, Inc. Process for the production of intermediate pressure oxygen
EP1338856A3 (en) * 2002-01-31 2003-09-10 L'AIR LIQUIDE, Société Anonyme à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des Process and apparatus for the separation of air by cryogenic distillation
FR2854232A1 (en) * 2003-04-23 2004-10-29 Air Liquide Air separation procedure to produce argon uses cryogenic distillation with additional liquid flow containing 18-30 mol percent oxygen fed to low pressure column
FR2864214B1 (en) * 2003-12-22 2017-04-21 Air Liquide AIR SEPARATION APPARATUS, INTEGRATED AIR SEPARATION AND METAL PRODUCTION APPARATUS AND METHOD FOR STARTING SUCH AIR SEPARATION APPARATUS
US20070095100A1 (en) * 2005-11-03 2007-05-03 Rankin Peter J Cryogenic air separation process with excess turbine refrigeration
US9279613B2 (en) * 2010-03-19 2016-03-08 Praxair Technology, Inc. Air separation method and apparatus
CN105115244B (en) * 2015-08-10 2017-06-27 开封空分集团有限公司 The device and method that a kind of low purity oxygen air is separate

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JPH0854181A (en) 1996-02-27
FR2718518B1 (en) 1996-05-03
EP0677713A1 (en) 1995-10-18
FR2718518A1 (en) 1995-10-13
DE69512821T2 (en) 2000-05-25
CN1121172A (en) 1996-04-24
CA2146831A1 (en) 1995-10-13
DE69512821D1 (en) 1999-11-25

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