EP0612967B1 - Process for the production of oxygen and/or nitrogen under pressure - Google Patents

Process for the production of oxygen and/or nitrogen under pressure Download PDF

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Publication number
EP0612967B1
EP0612967B1 EP94400372A EP94400372A EP0612967B1 EP 0612967 B1 EP0612967 B1 EP 0612967B1 EP 94400372 A EP94400372 A EP 94400372A EP 94400372 A EP94400372 A EP 94400372A EP 0612967 B1 EP0612967 B1 EP 0612967B1
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Prior art keywords
pressure
air
column
turbine
liquid
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German (de)
French (fr)
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EP0612967A1 (en
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Norbert Rieth
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Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—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
    • F25J3/04309—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 nitrogen
    • F25J3/04315—Lowest pressure or impure nitrogen, so-called waste nitrogen expansion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—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
    • F25J3/04248—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
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
    • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/20—Processes or apparatus using separation by rectification in an elevated pressure multiple column system wherein the lowest pressure column is at a pressure well above the minimum pressure needed to overcome pressure drop to reject the products to atmosphere
    • 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
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S62/00—Refrigeration
    • Y10S62/912—External refrigeration system
    • Y10S62/913—Liquified gas

Definitions

  • EP-A-0.420.725 describes a liquefier which uses a Claude turbine and a second low pressure air turbine.
  • the invention aims to improve the energy performance of known methods.
  • the installation shown in Figure 1 is intended to produce gaseous oxygen at a high pressure of approximately 3 to 100 bars, nitrogen gas at a low pressure of approximately 1.7 to 5 bars, oxygen liquid and liquid nitrogen.
  • This installation essentially comprises: a main air compressor 1; a pre-cooler 2; an adsorption purification device 3; a blower-turbine assembly comprising a blower 4 and a turbine 5, the wheels of which are fixed on the same shaft; an atmospheric or water cooler 6 for the fan; a heat exchange line 7; a second expansion turbine 8 braked by an alternator 9; a double distillation column 10 comprising a medium-pressure column 11 and a low-pressure column 12 coupled by a vaporizer-condenser 13 which places the head nitrogen of column 11 in heat exchange relationship with the liquid oxygen from the bottom column 12; a liquid oxygen pump 14; storage of liquid oxygen at atmospheric pressure; a storage 16 of liquid nitrogen at atmospheric pressure; a separator pot 17; and a sub-cooler 18.
  • the column 12 is under a pressure of approximately 1.7 to 5 bars, and the column 11 under the corresponding pressure of approximately 6.5 to 16 bars.
  • All the air to be distilled is compressed in 1, pre-cooled in 2 to + 5 to + 10 ° C, purified in water and CO2 in 3 and boosted in 4 at high pressure. After pre-cooling in 6 then partial cooling in 7 to an intermediate temperature T1, part of the air under high pressure continues to cool in the heat exchange line, is liquefied and then divided into two fractions. Each fraction is expanded in a respective expansion valve 19, 20, then introduced into the respective column 11, 12.
  • “rich liquid” (oxygen-enriched air) drawn off from the bottom of column 11 and “lean liquid” (almost pure nitrogen) drawn off at the top of this column are, after sub-cooling in 18 and expansion in respective expansion valves 21 and 22, introduced at an intermediate level and at the head, respectively, of the column 12.
  • Liquid oxygen is withdrawn from the tank of column 12. A fraction goes directly, after sub-cooling in 18 and expansion to atmospheric pressure in an expansion valve 23, in storage 15, while the rest is brought by the pump 14 at the desired high production pressure, then vaporized and warmed to room temperature in the heat exchange line before being recovered via a line 24.
  • liquid nitrogen under medium pressure drawn off at the top of column 11, is sub-cooled at 18, expanded at atmospheric pressure in an expansion valve 25, and introduced into the separator pot 17.
  • the phase liquid is sent to storage 16, while the vapor phase is reheated in 18 and then in 7 and recovered as a product (nitrogen low pressure gas) via a line 26.
  • the waste gas (impure nitrogen WN2) withdrawn at the head of column 12 is preheated in 18 and then partially reheated in 7, to an intermediate temperature T2. At this temperature, the waste gas is removed from the heat exchange line, expanded to atmospheric pressure in the turbine 8, which cools it, and reintroduced into the heat exchange line at the corresponding temperature, to then be reheated at room temperature and discharged via line 27.
  • the heat exchange diagram of Figure 2 was obtained by calculation with a low pressure of 2.2 bars, a medium pressure of 8.2 bars, a high air pressure of 32 bars and a high oxygen pressure 40 bars.
  • the inlet temperature T1 of the turbine 5 is slightly lower than the oxygen vaporization stage P, and the inlet temperature T2 of the turbine 8 is close to the knee G of air liquefaction.
  • the point R of the warming curve corresponds to the reintroduction into the exchange line of the turbinated residual gas, and the section of curve with increased slope, between this point R and the temperature T2, brings a tightening of the diagram in the corresponding cold part. thermodynamic improvement of the process.
  • the operation under pressure of column 12 results in a reduction in the purity of the oxygen produced.
  • the high pressure oxygen gas and the liquid oxygen stored at 15 typically have a purity of the order of 95%.
  • the invention also applies to the production of nitrogen gas under high pressure, brought by a pump (not shown) to the desired high pressure and then vaporized in the heat exchange line, and / or to the production of oxygen. and / or nitrogen under several pressures, using several high air pressures.
  • the vaporization of the liquid or liquids can be carried out in a manner not concomitant with the liquefaction of air, as in the example described above, or concomitantly with this liquefaction.

Description

La présente invention est relative à un procédé de production d'oxygène gazeux et/ou d'azote gazeux sous pression, du type dans lequel :

  • on distille de l'air dans une double colonne de distillation comprenant une colonne basse pression fonctionnant sous une pression dite basse pression, et une colonne moyenne pression fonctionnant sous une pression dite moyenne pression ;
  • on comprime la totalité de l'air à distiller jusqu'à au moins une haute pression d'air nettement supérieure à la moyenne pression ;
  • on refroidit l'air comprimé jusqu'à une température intermédiaire, et on en détend une partie dans une turbine jusqu'à la moyenne pression, avant de l'introduire dans la colonne moyenne pression ;
  • on liquéfie l'air non turbiné, puis on l'introduit, après détente dans la double colonne; et
  • on amène au moins un produit liquide soutiré de la double colonne à la pression de production, et on vaporise ce produit liquide par échange de chaleur avec l'air.
The present invention relates to a process for producing gaseous oxygen and / or nitrogen gas under pressure, of the type in which:
  • air is distilled in a double distillation column comprising a low pressure column operating under a pressure known as low pressure, and a medium pressure column operating under a pressure known as medium pressure;
  • all the air to be distilled is compressed to at least one high air pressure which is clearly higher than the medium pressure;
  • the compressed air is cooled to an intermediate temperature, and part of it is expanded in a turbine to medium pressure, before introducing it into the medium pressure column;
  • the non-turbinated air is liquefied, then introduced, after expansion in the double column; and
  • at least one liquid product withdrawn from the double column is brought to production pressure, and this liquid product is vaporized by heat exchange with air.

Les pressions dont il est question dans le présent mémoire sont des pressions absolues. De plus, l'expression "liquéfaction" doit être entendu au sens large, c'est-à-dire incluant la pseudo-liquéfaction dans le cas de pressions supercritiques.The pressures discussed in this brief are absolute pressures. In addition, the expression "liquefaction" must be understood in the broad sense, that is to say including pseudo-liquefaction in the case of supercritical pressures.

Un procédé de ce type est décrit dans FR-A-2.674.011.A process of this type is described in FR-A-2,674,011.

Il est également connu de DE-A-15.01.722 de fournir toutes les frigories nécessaires pour un procédé "à pompe" par une détente d'azote résiduaire, préchauffé contre l'air d'alimentation à une pression supercritique.It is also known from DE-A-15.01.722 to supply all the frigories necessary for a "pump" process by an expansion of residual nitrogen, preheated against the supply air at a supercritical pressure.

EP-A-0.420.725 décrit un liquéfacteur qui utilise une turbine Claude et une deuxième turbine d'air basse pression.EP-A-0.420.725 describes a liquefier which uses a Claude turbine and a second low pressure air turbine.

L'invention a pour but d'améliorer les performances énergétiques des procédés connus.The invention aims to improve the energy performance of known methods.

A cet effet, l'invention a pour objet un procédé du type précité, caractérisé en ce que :

  • on fait fonctionner la colonne basse pression sous pression ; et
  • on détend dans une seconde turbine le gaz résiduaire de tête de la colonne basse pression, après l'avoir partiellement réchauffé, et en ce que la température d'admission de la seconde turbine est voisine du genou de liquéfaction, ou du genou principal de liquéfaction, de l'air.
To this end, the subject of the invention is a method of the aforementioned type, characterized in that:
  • the low pressure column is operated under pressure; and
  • the residual gas at the head of the low pressure column is expanded in a second turbine, after having partially heated it, and in this that the intake temperature of the second turbine is close to the liquefaction knee, or the main liquefaction knee, of air.

Suivant des modes particuliers de réalisation de l'invention :

  • on fait fonctionner la colonne basse pression sous 1,7 à 5 bar environ, et la colonne moyenne pression sous une pression correspondante de 6,5 à 16 bar environ ;
  • la température d'entrée de la turbine d'air est plus élevée que la température d'entrée de la seconde turbine.
According to particular embodiments of the invention:
  • the low pressure column is operated at approximately 1.7 to 5 bar, and the medium pressure column at a corresponding pressure of approximately 6.5 to 16 bar;
  • the inlet temperature of the air turbine is higher than the inlet temperature of the second turbine.

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

  • la Figure 1 représente schématiquement une installation conforme à l'invention; et
  • la Figure 2 est un diagramme d'échange thermique correspondant à un mode de fonctionnement de cette installation, avec en abscisses les températures en degrés Celsius et en ordonnées les quantités de chaleur échangées entre l'air et les produits issus de la double colonne de distillation.
An example of implementation of the invention will be described with reference to the appended drawings, in which: which :
  • Figure 1 schematically shows an installation according to the invention; and
  • Figure 2 is a heat exchange diagram corresponding to a mode of operation of this installation, with abscissa temperatures in degrees Celsius and ordinates the amounts of heat exchanged between air and products from the double distillation column .

L'installation représentée à la Figure 1 est destinée à produire de l'oxygène gazeux sous une haute pression de 3 à 100 bars environ, de l'azote gazeux sous une basse pression de 1,7 à 5 bars environ, de l'oxygène liquide et de l'azote liquide.The installation shown in Figure 1 is intended to produce gaseous oxygen at a high pressure of approximately 3 to 100 bars, nitrogen gas at a low pressure of approximately 1.7 to 5 bars, oxygen liquid and liquid nitrogen.

Cette installation comprend essentiellement: un compresseur principal d'air 1; un pré-refroidisseur 2; un appareil 3 d'épuration par adsorption; un ensemble soufflante-turbine comprenant une soufflante 4 et une turbine 5 dont les roues sont calées sur le même arbre; un réfrigérant atmosphérique ou à eau 6 pour la soufflante; une ligne d'échange thermique 7; une seconde turbine de détente 8 freinée par un alternateur 9; une double colonne de distillation 10 comprenant une colonne moyenne pression 11 et une colonne basse pression 12 couplées par un vaporiseur- condenseur 13 qui met en relation d'échange thermique l'azote de tête de la colonne 11 et l'oxygène liquide de cuve de la colonne 12; une pompe d'oxygène liquide 14; un stockage 15 d'oxygène liquide à la pression atmosphérique; un stockage 16 d'azote liquide à la pression atmosphérique; un pot séparateur 17; et un sous-refroidisseur 18.This installation essentially comprises: a main air compressor 1; a pre-cooler 2; an adsorption purification device 3; a blower-turbine assembly comprising a blower 4 and a turbine 5, the wheels of which are fixed on the same shaft; an atmospheric or water cooler 6 for the fan; a heat exchange line 7; a second expansion turbine 8 braked by an alternator 9; a double distillation column 10 comprising a medium-pressure column 11 and a low-pressure column 12 coupled by a vaporizer-condenser 13 which places the head nitrogen of column 11 in heat exchange relationship with the liquid oxygen from the bottom column 12; a liquid oxygen pump 14; storage of liquid oxygen at atmospheric pressure; a storage 16 of liquid nitrogen at atmospheric pressure; a separator pot 17; and a sub-cooler 18.

En fonctionnement, la colonne 12 est sous une pression de 1,7 à 5 bars environ, et la colonne 11 sous la pression correspondante de 6,5 à 16 bars environ.In operation, the column 12 is under a pressure of approximately 1.7 to 5 bars, and the column 11 under the corresponding pressure of approximately 6.5 to 16 bars.

La totalité de l'air à distiller est comprimé en 1, pré-refroidi en 2 vers + 5 à + 10°C, épuré en eau et en CO2 en 3 et surpressé en 4 à la haute pression. Après pré-refroidissement en 6 puis refroidissement partiel en 7 jusqu'à une température intermédiaire T1, une partie de l'air sous la haute pression poursuit son refroidissement dans la ligne d'échange thermique, est liquéfié puis divisé en deux fractions. Chaque fraction est détendue dans une vanne de détente respective 19, 20, puis introduite dans la colonne 11, 12 respective.All the air to be distilled is compressed in 1, pre-cooled in 2 to + 5 to + 10 ° C, purified in water and CO2 in 3 and boosted in 4 at high pressure. After pre-cooling in 6 then partial cooling in 7 to an intermediate temperature T1, part of the air under high pressure continues to cool in the heat exchange line, is liquefied and then divided into two fractions. Each fraction is expanded in a respective expansion valve 19, 20, then introduced into the respective column 11, 12.

A la température T1, le reste de l'air sous la haute pression est sorti de la ligne d'échange thermique, turbiné en 5 à la moyenne pression et introduit en cuve de la colonne 11.At the temperature T1, the rest of the air under the high pressure is removed from the heat exchange line, turbinated at 5 at medium pressure and introduced into the tank of the column 11.

De façon habituelle, du "liquide riche" (air enrichi en oxygène) soutiré en cuve de la colonne 11 et du "liquide pauvre" (azote à peu près pur) soutiré en tête de cette colonne sont, après sous-refroidissement en 18 et détente dans des vannes de détente respectives 21 et 22, introduits à un niveau intermédiaire et en tête, respectivement, de la colonne 12.Usually, "rich liquid" (oxygen-enriched air) drawn off from the bottom of column 11 and "lean liquid" (almost pure nitrogen) drawn off at the top of this column are, after sub-cooling in 18 and expansion in respective expansion valves 21 and 22, introduced at an intermediate level and at the head, respectively, of the column 12.

De l'oxygène liquide est soutiré en cuve de la colonne 12. Une fraction va directement, après sous-refroidissement en 18 et détente à la pression atmosphérique dans une vanne de détente 23, dans le stockage 15, tandis que le reste est amené par la pompe 14 à la haute pression de production désirée, puis vaporisé et réchauffé à la température ambiante dans la ligne d'échange thermique avant d'être récupéré via une conduite 24.Liquid oxygen is withdrawn from the tank of column 12. A fraction goes directly, after sub-cooling in 18 and expansion to atmospheric pressure in an expansion valve 23, in storage 15, while the rest is brought by the pump 14 at the desired high production pressure, then vaporized and warmed to room temperature in the heat exchange line before being recovered via a line 24.

Par ailleurs, de l'azote liquide sous la moyenne pression, soutiré en tête de la colonne 11, est sous-refroidi en 18, détendu à la pression atmosphérique dans une vanne de détente 25, et introduit dans le pot séparateur 17. La phase liquide est envoyée dans le stockage 16, tandis que la phase vapeur est réchauffée en 18 puis en 7 et récupérée en tant que produit (azote gazeux basse pression) via une conduite 26.Furthermore, liquid nitrogen under medium pressure, drawn off at the top of column 11, is sub-cooled at 18, expanded at atmospheric pressure in an expansion valve 25, and introduced into the separator pot 17. The phase liquid is sent to storage 16, while the vapor phase is reheated in 18 and then in 7 and recovered as a product (nitrogen low pressure gas) via a line 26.

Le gaz résiduaire (azote impur WN2) soutiré en tête de la colonne 12 est pré-réchauffé en 18 puis partiellement réchauffé, en 7, jusqu'à une température intermédiaire T2. A cette température, le gaz résiduaire est sorti de la ligne d'échange thermique, détendu à la pression atmosphérique dans la turbine 8, ce qui le refroidit, et réintroduit dans la ligne d'échange thermique à la température correspondante, pour être ensuite réchauffé à la température ambiante et évacué via une conduite 27.The waste gas (impure nitrogen WN2) withdrawn at the head of column 12 is preheated in 18 and then partially reheated in 7, to an intermediate temperature T2. At this temperature, the waste gas is removed from the heat exchange line, expanded to atmospheric pressure in the turbine 8, which cools it, and reintroduced into the heat exchange line at the corresponding temperature, to then be reheated at room temperature and discharged via line 27.

Le diagramme d'échange thermique de la Figure 2 a été obtenu par calcul avec une basse pression de 2,2 bars, une moyenne pression de 8,2 bars, une haute pression d'air de 32 bars et une haute pression d'oxygène de 40 bars. La température T1 d'admission de la turbine 5 est légèrement inférieure au palier P de vaporisation de l'oxygène, et la température T2 d'admission de la turbine 8 est voisine du genou G de liquéfaction de l'air. Le point R de la courbe de réchauffement correspond à la réintroduction dans la ligne d'échange du gaz résiduaire turbiné, et le tronçon de courbe à pente accrue, entre ce point R et la température T2, apporte un resserrement du diagramme en partie froide correspondant à une amélioration thermodynamique du procédé.The heat exchange diagram of Figure 2 was obtained by calculation with a low pressure of 2.2 bars, a medium pressure of 8.2 bars, a high air pressure of 32 bars and a high oxygen pressure 40 bars. The inlet temperature T1 of the turbine 5 is slightly lower than the oxygen vaporization stage P, and the inlet temperature T2 of the turbine 8 is close to the knee G of air liquefaction. The point R of the warming curve corresponds to the reintroduction into the exchange line of the turbinated residual gas, and the section of curve with increased slope, between this point R and the temperature T2, brings a tightening of the diagram in the corresponding cold part. thermodynamic improvement of the process.

On peut ainsi produire une quantité de liquide accrue, avec une énergie spécifique de production de l'oxygène gazeux haute pression réduite.It is thus possible to produce an increased quantity of liquid, with a specific energy for the production of reduced high pressure oxygen gas.

Le fonctionnement sous pression de la colonne 12 a pour conséquence une baisse de pureté de l'oxygène produit. Ainsi, l'oxygène gazeux haute pression et l'oxygène liquide stocké en 15 ont typiquement une pureté de l'ordre de 95%. Cependant, il est possible de prévoir quelques plateaux de distillation entre les soutirages d'oxygène liquide destinés d'une part au stockage 15, d'autre part à la pompe 14, et de produire ainsi une fraction, par exemple 20% de l'oxygène, sous forme d'oxygène liquide à pureté élevée, typiquement à 99,5% de pureté.The operation under pressure of column 12 results in a reduction in the purity of the oxygen produced. Thus, the high pressure oxygen gas and the liquid oxygen stored at 15 typically have a purity of the order of 95%. However, it is possible to provide some distillation trays between the liquid oxygen withdrawals intended on the one hand for storage 15, on the other hand to the pump 14, and thus to produce a fraction, for example 20% of the oxygen, in the form of liquid oxygen with high purity, typically at 99.5% purity.

L'invention s'applique également à la production d'azote gazeux sous haute pression, porté par une pompe (non représentée) à la haute pression désirée puis vaporisé dans la ligne d'échange thermique, et/ou à la production d'oxygène et/ou d'azote sous plusieurs pressions, en utilisant plusieurs hautes pressions d'air. De plus, la vaporisation du ou des liquides peut s'effectuer de façon non concomitante à la liquéfaction d'air, comme dans l'exemple décrit plus haut, ou de façon concomitante à cette liquéfaction.The invention also applies to the production of nitrogen gas under high pressure, brought by a pump (not shown) to the desired high pressure and then vaporized in the heat exchange line, and / or to the production of oxygen. and / or nitrogen under several pressures, using several high air pressures. In addition, the vaporization of the liquid or liquids can be carried out in a manner not concomitant with the liquefaction of air, as in the example described above, or concomitantly with this liquefaction.

Claims (5)

  1. Process for producing gaseous oxygen and/or gaseous nitrogen under pressure, of the type in which :
    - air is distilled in a double distillation column (10) comprising a low pressure column (12) operating at a pressure known as the low pressure, and a medium pressure column (11) operating at a pressure known as the medium pressure;
    - all the air to be distilled is compressed (in 1, 4) to at least one high air pressure appreciably greater than the medium pressure;
    - the compressed air is cooled to an intermediate temperature and a part of this is expanded in a turbine (5) to the medium pressure before introducing it into the medium pressure column (11);
    - the non-turbined air is liquefied and then introduced, after expansion (in 19, 20), in the double column; and
    - at least one liquid product withdrawn from the double column is brought to the production pressure and this liquid product is vaporised by heat exchange with air,
    characterized in that :
    - the low pressure column (12) is operated under pressure; and
    - the residual gas from the top of the low pressure column is expanded in a second turbine (8), after having been partially reheated, and in that the inlet temperature (T2) of the second turbine (8) is close to the liquefaction step (G) or of the main liquefaction step of air.
  2. Process according to claim 1, characterized in that the low pressure column (12) is operated at approximately 1.7 to 5 bar and the medium pressure column (11) at a pressure corresponding to approximately 6.5 to 16 bar.
  3. Process according to claim 1 or 2, characterized in that the inlet temperature of the air turbine (5) is higher than the inlet temperature of the second turbine (8).
  4. Process according to one of the preceding claims wherein liquid oxygen is withdrawn which is intended to be vaporised by heat exchange with the air a few plates above the point where liquid oxygen is withdrawn for storage (15).
  5. Process according to one of claims 1 to 3 wherein the liquid product or one of the liquid products is liquid nitrogen.
EP94400372A 1993-02-25 1994-02-22 Process for the production of oxygen and/or nitrogen under pressure Expired - Lifetime EP0612967B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9302137 1993-02-25
FR9302137A FR2702040B1 (en) 1993-02-25 1993-02-25 Process and installation for the production of oxygen and / or nitrogen under pressure.

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EP0612967A1 EP0612967A1 (en) 1994-08-31
EP0612967B1 true EP0612967B1 (en) 1997-04-23

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EP (1) EP0612967B1 (en)
JP (1) JPH06249574A (en)
CN (1) CN1081780C (en)
AU (1) AU672859B2 (en)
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ES (1) ES2102780T3 (en)
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US5355682A (en) † 1993-09-15 1994-10-18 Air Products And Chemicals, Inc. Cryogenic air separation process producing elevated pressure nitrogen by pumped liquid nitrogen
FR2730172B1 (en) * 1995-02-07 1997-03-21 Air Liquide METHOD AND APPARATUS FOR MONITORING THE OPERATION OF AN AIR SEPARATION INSTALLATION
US5924307A (en) * 1997-05-19 1999-07-20 Praxair Technology, Inc. Turbine/motor (generator) driven booster compressor
US20070095100A1 (en) * 2005-11-03 2007-05-03 Rankin Peter J Cryogenic air separation process with excess turbine refrigeration
US7552599B2 (en) * 2006-04-05 2009-06-30 Air Products And Chemicals, Inc. Air separation process utilizing refrigeration extracted from LNG for production of liquid oxygen
US9714789B2 (en) * 2008-09-10 2017-07-25 Praxair Technology, Inc. Air separation refrigeration supply method
DE102011113262A1 (en) * 2011-09-13 2013-03-14 Linde Aktiengesellschaft Process and apparatus for recovering pressure oxygen by cryogenic separation of air
CN109737691B (en) * 2019-01-31 2020-05-19 东北大学 Air separation system of iron and steel enterprise

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FR1148546A (en) * 1956-09-27 1957-12-11 Air Liquide Process of separating air into its elements
GB943669A (en) * 1961-11-03 1963-12-04 Petrocarbon Dev Ltd Separation of oxygen from air
DE1501722A1 (en) * 1966-01-13 1969-06-26 Linde Ag Process for cryogenic air separation for the production of highly compressed gaseous and / or liquid oxygen
US3375673A (en) * 1966-06-22 1968-04-02 Hydrocarbon Research Inc Air separation process employing work expansion of high and low pressure nitrogen
US3589137A (en) * 1967-10-12 1971-06-29 Mc Donnell Douglas Corp Method and apparatus for separating nitrogen and hydrocarbons by fractionation using the fluids-in-process for condenser and reboiler duty
DE2535132C3 (en) * 1975-08-06 1981-08-20 Linde Ag, 6200 Wiesbaden Process and device for the production of pressurized oxygen by two-stage low-temperature rectification of air
BR7606681A (en) * 1975-10-28 1977-11-16 Linde Ag AIR FRACTIONATION PROCESS AND INSTALLATION
FR2461906A1 (en) * 1979-07-20 1981-02-06 Air Liquide CRYOGENIC AIR SEPARATION METHOD AND INSTALLATION WITH OXYGEN PRODUCTION AT HIGH PRESSURE
GB2129115B (en) * 1982-10-27 1986-03-12 Air Prod & Chem Producing gaseous nitrogen
FR2652409A1 (en) * 1989-09-25 1991-03-29 Air Liquide REFRIGERANT PRODUCTION PROCESS, CORRESPONDING REFRIGERANT CYCLE AND THEIR APPLICATION TO AIR DISTILLATION.
GB9015377D0 (en) * 1990-07-12 1990-08-29 Boc Group Plc Air separation
JP2909678B2 (en) * 1991-03-11 1999-06-23 レール・リキード・ソシエテ・アノニム・プール・レテュード・エ・レクスプロワタシオン・デ・プロセデ・ジョルジュ・クロード Method and apparatus for producing gaseous oxygen under pressure

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FR2702040A1 (en) 1994-09-02
ES2102780T3 (en) 1997-08-01
CN1081780C (en) 2002-03-27
CA2116297A1 (en) 1994-08-26
DE69402745T2 (en) 1997-11-13
AU5634794A (en) 1994-09-01
CN1093158A (en) 1994-10-05
FR2702040B1 (en) 1995-05-19
ZA941279B (en) 1994-09-30
AU672859B2 (en) 1996-10-17
EP0612967A1 (en) 1994-08-31
JPH06249574A (en) 1994-09-06
CA2116297C (en) 2004-12-07
DE69402745D1 (en) 1997-05-28
US5515688A (en) 1996-05-14

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