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EP0595673B1 - Process and installation for the production of nitrogen and oxygen - Google Patents

Process and installation for the production of nitrogen and oxygen Download PDF

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Publication number
EP0595673B1
EP0595673B1 EP93402421A EP93402421A EP0595673B1 EP 0595673 B1 EP0595673 B1 EP 0595673B1 EP 93402421 A EP93402421 A EP 93402421A EP 93402421 A EP93402421 A EP 93402421A EP 0595673 B1 EP0595673 B1 EP 0595673B1
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EP
European Patent Office
Prior art keywords
column
liquid
reboiler
condenser
nitrogen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93402421A
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German (de)
French (fr)
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EP0595673A1 (en
Inventor
Pascal Arriulou
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 EP0595673A1 publication Critical patent/EP0595673A1/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
    • F25J3/044—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
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04296—Claude expansion, i.e. expanded into the main or high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—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
    • 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
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04872—Vertical layout of cold equipments within in the cold box, e.g. columns, heat exchangers etc.
    • F25J3/04884—Arrangement of reboiler-condensers
    • 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
    • F25J2200/50—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the 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
    • F25J2200/72—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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/76—Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
    • 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
    • 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
    • F25J2250/20—Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams
    • 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
    • Y10S62/939—Partial feed stream expansion, air

Definitions

  • DE-A-30.35.844 describes a process for the production of nitrogen and impure oxygen.
  • the supply air is used to reboil the tank of the single column and a liquid is drawn off at an intermediate level of the column to be sent to the overhead condenser with the rich liquid.
  • the object of the invention is to improve this process so as to also allow a minority production of oxygen.
  • the installation represented in FIG. 1 essentially comprises an air compressor 1, an apparatus 2 for purifying the air of water and CO 2 by adsorption, a heat exchange line 3, a distillation column 4, an air expansion turbine 5, an auxiliary heat exchanger 6 and a nitrogen compressor 7.
  • Column 4 comprises an overhead condenser 8 and a tank reboiler 9. This column operates under a pressure known as medium pressure, typically of the order of 3 to 5 bars absolute.
  • the air to be treated compressed by the compressor 1 at a pressure markedly higher than the medium pressure and then purified in 2, is cooled to an intermediate temperature in the heat exchange line 3. A fraction of the air is then out of heat exchange line, expanded at medium pressure in turbine 5 and introduced at an intermediate level in column 4.
  • Production nitrogen gas is drawn off at the top of the column via a pipe 11, heated in 6 then in 3, and recovered as the first product (medium-pressure nitrogen gas) via a pipe 12.
  • An adjustable flow of medium pressure nitrogen is taken from line 12 and compressed to a high pressure by compressor 7. Part of the high pressure nitrogen can constitute a second product of the installation, recovered via line 13, and the rest is recycled via a pipe 14, cooled to the cold end of the exchange line 3 and sent to the reboiler 9, where it condenses.
  • the liquid nitrogen thus obtained, sub-cooled in 6, is expanded in an expansion valve 15 and injected under reflux at the top of the column 4, part of this liquid nitrogen being able to be recovered as a third product (liquid nitrogen under high pressure) via a 15A line.
  • a liquid, called “rich liquid” is withdrawn, via a line 16, at an intermediate level between the level of introduction of the turbined air and the reboiler, that is to say that there are a certain number of distillation plates 17 between line 16 and the introduction of the turbined air and a certain number of plates 18 below line 16.
  • This liquid is sub-cooled in 6, expanded at a low pressure slightly higher than the atmospheric pressure in an expansion valve 19 and introduced into the condenser 8, where it vaporizes.
  • the rich liquid vaporized, after heating in 6 and then in the heat exchange line 3, is discharged via a pipe 19 constituting the waste gas W of the installation.
  • the bottom liquid of the column which cools the reboiler 9, consists of oxygen at a desired content of impurities.
  • a relatively low flow rate of this liquid of the order of a few% of the incoming air flow rate, is vaporized by the reboiler 9 and withdrawn from the column in gaseous form immediately above it via a line 20, c that is to say that there is no distillation stage between the reboiler and this pipe 20.
  • this medium-pressure gaseous oxygen constitutes a fourth product of the installation, which is recovered via a line 21.
  • a pipe 22 for purging liquid oxygen from the bottom of the column is also shown in Figure 1, a pipe 22 for purging liquid oxygen from the bottom of the column.
  • the pipe 20 is deleted, and a pipe 23 is pitted on the pipe 22.
  • the liquid oxygen conveyed by this line 23 is sub-cooled at 6, expanded in an expansion valve 24 and introduced into an auxiliary condenser 25 mounted in the column 4 below the head condenser 8, to be vaporized there.
  • the expression "below” means that there are a number of distillation trays between the two condensers.
  • This variant makes it possible to increase the reflux in column 4, in return for the production of gaseous oxygen under low pressure.
  • the embodiment 3 differs from the previous one only in that the auxiliary condenser 25 is mounted in parallel with the head condenser 8 and therefore constitutes a second head condenser of the column.
  • the production of the column is thereby simplified, but, on the other hand, it is necessary to slightly increase the pressure of the rich liquid vaporized and therefore the pressure of the incoming air.

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

Description

La présente invention est relative à un procédé de production majoritaire d'azote et minoritaire d'oxygène par distillation d'un mélange gazeux, notamment d'air, du type dans lequel :

  • le mélange gazeux est refroidi dans une ligne d'échange puis introduit à un niveau intermédiaire d'une colonne de distillation fonctionnant à une moyenne pression et équipée d'un condenseur de tête et d'un rebouilleur de cuve ;
  • du liquide soutiré de la colonne au-dessous du point d'introduction du mélange gazeux est, après détente à une basse pression inférieure à la moyenne pression, vaporisé dans le condenseur de tête ;
  • de l'azote gazeux est soutiré en tête de colonne et réchauffé et, pour partie, comprimé à une haute pression supérieure à la moyenne pression, refroidi et introduit dans le rebouilleur pour y être condensé ; et
  • une partie au moins de l'azote liquide ainsi obtenu est détendue à la moyenne pression et, éventuellement après épuration, introduite en tête de la colonne.
The present invention relates to a process for the majority production of nitrogen and the majority of oxygen by distillation of a gaseous mixture, in particular of air, of the type in which:
  • the gas mixture is cooled in an exchange line then introduced at an intermediate level of a distillation column operating at medium pressure and equipped with a head condenser and a tank reboiler;
  • liquid withdrawn from the column below the point of introduction of the gaseous mixture is, after expansion at a low pressure below the medium pressure, vaporized in the overhead condenser;
  • nitrogen gas is withdrawn at the top of the column and heated and, in part, compressed to a high pressure higher than the medium pressure, cooled and introduced into the reboiler to be condensed there; and
  • at least part of the liquid nitrogen thus obtained is expanded at medium pressure and, optionally after purification, introduced at the top of the column.

Un tel procédé, décrit dans EP-A-413.631 en vue de produire uniquement de l'azote, présente l'avantage de pouvoir commander le taux de reflux dans la colonne, indépendamment du débit d'azote produit.Such a process, described in EP-A-413,631 with a view to producing nitrogen only, has the advantage of being able to control the rate of reflux in the column, independently of the flow of nitrogen produced.

DE-A-30.35.844 décrit un procédé de production d'azote et d'oxygène impur. L'air d'alimentation sert à rebouillir la cuve de la simple colonne et un liquide est soutiré à un niveau intermédiaire de la colonne pour être envoyé au condenseur de tête avec le liquide riche.DE-A-30.35.844 describes a process for the production of nitrogen and impure oxygen. The supply air is used to reboil the tank of the single column and a liquid is drawn off at an intermediate level of the column to be sent to the overhead condenser with the rich liquid.

L'invention a pour but de perfectionner ce procédé de manière à permettre en outre une production minoritaire d'oxygène.The object of the invention is to improve this process so as to also allow a minority production of oxygen.

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

  • ledit liquide est soutiré à un niveau intermédiaire entre le niveau d'injection d'air et le rebouilleur et réchauffé dans la ligne d'échange avant d'être évacué comme gaz résiduaire ; et
  • du liquide de cuve de la colonne est vaporisé et récupéré en tant que produit minoritaire constitué essentiellement d'oxygène.
To this end, the subject of the invention is a method of the aforementioned type, characterized in that:
  • said liquid is withdrawn at an intermediate level between the air injection level and the reboiler and heated in the exchange line before being discharged as waste gas; and
  • liquid from the bottom of the column is vaporized and recovered as a minority product consisting essentially of oxygen.

Suivant des modes particuliers de réalisation de l'invention :

  • le liquide de cuve destiné à constituer ledit produit minoritaire est vaporisé par le rebouilleur et soutiré sous forme gazeuse immédiatement au-dessus de celui-ci ;
  • le liquide de cuve destiné à constituer ledit produit minoritaire est détendu puis vaporisé dans un condenseur auxiliaire prévu dans la partie supérieure de la colonne ;
  • le condenseur auxiliaire est prévu au-dessous du condenseur de tête ;
  • le condenseur auxiliaire est prévu en parallèle avec le condenseur de tête, ledit liquide de cuve étant détendu à une pression inférieure à ladite basse pression.
According to particular embodiments of the invention:
  • the tank liquid intended to constitute said minority product is vaporized by the reboiler and drawn off in gaseous form immediately above the latter;
  • the tank liquid intended to constitute said minority product is expanded and then vaporized in an auxiliary condenser provided in the upper part of the column;
  • the auxiliary condenser is provided below the head condenser;
  • the auxiliary condenser is provided in parallel with the head condenser, said tank liquid being expanded to a pressure lower than said low pressure.

L'invention a également pour objet une installation destinée à la mise en oeuvre d'un tel procédé. Cette installation, du type comprenant :

  • une colonne de distillation fonctionnant sous une moyenne pression et équipée d'un condenseur de tête et d'un rebouilleur de cuve ;
  • des moyens pour comprimer, épurer et refroidir le mélange gazeux et l'introduire à un niveau intermédiaire de la colonne ;
  • des moyens pour soutirer un liquide à un niveau de la colonne inférieur au niveau d'introduction du mélange gazeux, des moyens pour détendre ce liquide à une basse pression et des moyens pour l'introduire en vue de sa vaporisation dans le condenseur de tête;
  • des moyens pour soutirer de l'azote en tête de colonne, et des moyens pour réchauffer, comprimer à une haute pression, refroidir et introduire dans le rebouilleur une partie de cet azote; et
  • des moyens pour détendre à la moyenne pression une partie au moins de l'azote liquide issu du rebouilleur et pour l'introduire en tête de la colonne, est caractérisée en ce que :
  • le niveau de soutirage dudit liquide est intermédiaire entre le niveau d'introduction du mélange gazeux et le rebouilleur ; et
  • il est prévu des moyens pour vaporiser du liquide de cuve de la colonne et pour récupérer le gaz résultant, constitué essentiellement d'oxygène, en tant que produit minoritaire de l'installation.
The invention also relates to an installation intended for the implementation of such a method. This installation, of the type comprising:
  • a distillation column operating under medium pressure and equipped with a head condenser and a tank reboiler;
  • means for compressing, purifying and cooling the gas mixture and introducing it at an intermediate level of the column;
  • means for withdrawing a liquid at a level of the column lower than the level of introduction of the gaseous mixture, means for expanding this liquid to a low pressure and means for introducing it with a view to its vaporization in the head condenser;
  • means for withdrawing nitrogen at the top of the column, and means for heating, compressing at high pressure, cool and introduce part of this nitrogen into the reboiler; and
  • means for relaxing at medium pressure at least part of the liquid nitrogen coming from the reboiler and for introducing it at the top of the column, is characterized in that:
  • the level of withdrawal of said liquid is intermediate between the level of introduction of the gas mixture and the reboiler; and
  • means are provided for vaporizing liquid from the bottom of the column and for recovering the resulting gas, essentially consisting of oxygen, as a minority product of the installation.

Des exemples de mise en oeuvre de l'invention vont maintenant être décrits en regard des dessins annexés, sur lesquels les Figures 1 à 3 représentent schématiquement trois modes de réalisation d'une installation de production d'azote et d'oxygène conforme à l'invention.Examples of implementation of the invention will now be described with reference to the accompanying drawings, in which Figures 1 to 3 schematically represent three embodiments of a nitrogen and oxygen production installation in accordance with invention.

L'installation représentée à la Figure 1 comprend essentiellement un compresseur d'air 1, un appareil 2 d'épuration de l'air en eau et en CO2 par adsorption, une ligne d'échange thermique 3, une colonne de distillation 4, une turbine 5 de détente d'air, un échangeur de chaleur auxiliaire 6 et un compresseur d'azote 7. La colonne 4 comporte un condenseur de tête 8 et un rebouilleur de cuve 9. Cette colonne fonctionne sous une pression dite moyenne pression, typiquement de l'ordre de 3 à 5 bars absolus.The installation represented in FIG. 1 essentially comprises an air compressor 1, an apparatus 2 for purifying the air of water and CO 2 by adsorption, a heat exchange line 3, a distillation column 4, an air expansion turbine 5, an auxiliary heat exchanger 6 and a nitrogen compressor 7. Column 4 comprises an overhead condenser 8 and a tank reboiler 9. This column operates under a pressure known as medium pressure, typically of the order of 3 to 5 bars absolute.

L'air à traiter, comprimé par le compresseur 1 à une pression nettement supérieure à la moyenne pression puis épuré en 2, est refroidi jusqu'à une température intermédiaire dans la ligne d'échange thermique 3. Une fraction de l'air est alors sorti de ligne d'échange thermique, détendu à la moyenne pression dans la turbine 5 et introduit à un niveau intermédiaire dans la colonne 4.The air to be treated, compressed by the compressor 1 at a pressure markedly higher than the medium pressure and then purified in 2, is cooled to an intermediate temperature in the heat exchange line 3. A fraction of the air is then out of heat exchange line, expanded at medium pressure in turbine 5 and introduced at an intermediate level in column 4.

Le reste de l'air poursuit son refroidissement jusqu'à liquéfaction et sous-refroidissement et, après détente dans une vanne de détente 10, est introduit dans la colonne 4 au-dessus du premier flux d'air précité.The rest of the air continues its cooling until liquefaction and sub-cooling and, after expansion in an expansion valve 10, is introduced into column 4 above the first aforementioned first air flow.

De l'azote gazeux de production est soutiré en tête de colonne via une conduite 11, réchauffé en 6 puis en 3, et récupéré en tant que premier produit (azote gazeux moyenne pression) via une conduite 12.Production nitrogen gas is drawn off at the top of the column via a pipe 11, heated in 6 then in 3, and recovered as the first product (medium-pressure nitrogen gas) via a pipe 12.

Un débit réglable d'azote moyenne pression est prélevé sur la conduite 12 et comprimé à une haute pression par le compresseur 7. Une partie de l'azote haute pression peut constituer un deuxième produit de l'installation, récupéré via une conduite 13, et le reste est recyclé via une conduite 14, refroidi jusqu'au bout froid de la ligne d'échange 3 et envoyé dans le rebouilleur 9, où il se condense.An adjustable flow of medium pressure nitrogen is taken from line 12 and compressed to a high pressure by compressor 7. Part of the high pressure nitrogen can constitute a second product of the installation, recovered via line 13, and the rest is recycled via a pipe 14, cooled to the cold end of the exchange line 3 and sent to the reboiler 9, where it condenses.

L'azote liquide ainsi obtenu, sous-refroidi en 6, est détendu dans une vanne de détente 15 et injecté en reflux en tête de la colonne 4, une partie de cet azote liquide pouvant être récupéré en tant que troisième produit (azote liquide sous la haute pression) via une conduite 15A.The liquid nitrogen thus obtained, sub-cooled in 6, is expanded in an expansion valve 15 and injected under reflux at the top of the column 4, part of this liquid nitrogen being able to be recovered as a third product (liquid nitrogen under high pressure) via a 15A line.

Un liquide, dit "liquide riche" est soutiré, via une conduite 16, à un niveau intermédiaire entre le niveau d'introduction de l'air turbiné et le rebouilleur, c'est-à-dire qu'il existe un certain nombre de plateaux de distillation 17 entre la conduite 16 et l'introduction de l'air turbiné et un certain nombre de plateaux 18 au-dessous de la conduite 16. Ce liquide est sous-refroidi en 6, détendu à une basse pression légèrement supérieure à la pression atmosphérique dans une vanne de détente 19 et introduit dans le condenseur 8, où il se vaporise. Le liquide riche vaporisé, après réchauffement en 6 puis dans la ligne d'échange thermique 3, est évacué via une conduite 19 en constituant le gaz résiduaire W de l'installation.A liquid, called "rich liquid" is withdrawn, via a line 16, at an intermediate level between the level of introduction of the turbined air and the reboiler, that is to say that there are a certain number of distillation plates 17 between line 16 and the introduction of the turbined air and a certain number of plates 18 below line 16. This liquid is sub-cooled in 6, expanded at a low pressure slightly higher than the atmospheric pressure in an expansion valve 19 and introduced into the condenser 8, where it vaporizes. The rich liquid vaporized, after heating in 6 and then in the heat exchange line 3, is discharged via a pipe 19 constituting the waste gas W of the installation.

Le liquide de cuve de la colonne, qui refroidit le rebouilleur 9, est constitué d'oxygène à une teneur désirée en impuretés. Un débit de ce liquide relativement faible, de l'ordre de quelques % du débit d'air entrant, est vaporisé par le rebouilleur 9 et soutiré de la colonne sous forme gazeuse immédiatement au-dessus de celui-ci via une conduite 20, c'est-à-dire qu'il n'existe aucun plateau de distillation entre le rebouilleur et cette conduite 20.The bottom liquid of the column, which cools the reboiler 9, consists of oxygen at a desired content of impurities. A relatively low flow rate of this liquid, of the order of a few% of the incoming air flow rate, is vaporized by the reboiler 9 and withdrawn from the column in gaseous form immediately above it via a line 20, c that is to say that there is no distillation stage between the reboiler and this pipe 20.

Après réchauffement dans la ligne d'échange thermique, cet oxygène gazeux moyenne pression constitue un quatrième produit de l'installation, qui est récupéré via une conduite 21.After heating in the heat exchange line, this medium-pressure gaseous oxygen constitutes a fourth product of the installation, which is recovered via a line 21.

On a également représenté sur la Figure 1, une conduite 22 de purge d'oxygène liquide partant de la cuve de la colonne.Also shown in Figure 1, a pipe 22 for purging liquid oxygen from the bottom of the column.

On peut ainsi, par le simple choix des nombres de plateaux 17 et 18, produire de l'oxygène sous la pureté désirée, en plus de l'azote, qui constitue le produit largement majoritaire de l'installation. De même que dans le procédé du EP-A-413 631 précité, le reflux de la colonne peut être commandé par le débit d'azote haute pression recyclé en 14, indépendamment de la production d'azote et d'oxygène.It is thus possible, by the simple choice of the number of plates 17 and 18, to produce oxygen under the desired purity, in addition to nitrogen, which constitutes the largely majority product of the installation. As in the process of the aforementioned EP-A-413 631, the reflux of the column can be controlled by the flow of high pressure nitrogen recycled at 14, independently of the production of nitrogen and oxygen.

Le mode de réalisation de la Figure 2 ne diffère de celui de la Figure 1 que par la manière dont est obtenu l'oxygène gazeux à partir du liquide de cuve de la colonne.The embodiment of Figure 2 differs from that of Figure 1 only in the manner in which the gaseous oxygen is obtained from the bottom liquid of the column.

En effet, dans ce cas, la conduite 20 est supprimée, et une conduite 23 est piquée sur la conduite 22. L'oxygène liquide véhiculé par cette conduite 23 est sous-refroidi en 6, détendu dans une vanne de détente 24 et introduit dans un condenseur auxiliaire 25 monté dans la colonne 4 au-dessous du condenseur de tête 8, pour y être vaporisé. Comme précédemment, l'expression "au-dessous" signifie qu'il existe un certain nombre de plateaux de distillation entre les deux condenseurs.Indeed, in this case, the pipe 20 is deleted, and a pipe 23 is pitted on the pipe 22. The liquid oxygen conveyed by this line 23 is sub-cooled at 6, expanded in an expansion valve 24 and introduced into an auxiliary condenser 25 mounted in the column 4 below the head condenser 8, to be vaporized there. . As before, the expression "below" means that there are a number of distillation trays between the two condensers.

On produit ainsi de l'oxygène gazeux basse pression, réchauffé dans la ligne d'échange thermique puis récupéré via une conduite 26.Low pressure gaseous oxygen is thus produced, heated in the heat exchange line and then recovered via a pipe 26.

Cette variante permet d'augmenter le reflux dans la colonne 4, en contrepartie de la production de l'oxygène gazeux sous basse pression.This variant makes it possible to increase the reflux in column 4, in return for the production of gaseous oxygen under low pressure.

Le mode de la réalisation 3 ne diffère du précédent que par le fait que le condenseur auxiliaire 25 est monté en parallèle avec le condenseur de tête 8 et constitue donc un second condenseur de tête de la colonne. La réalisation de la colonne s'en trouve simplifiée, mais, en revanche, il est nécessaire d'augmenter légèrement la pression du liquide riche vaporisé et donc la pression de l'air entrant.The embodiment 3 differs from the previous one only in that the auxiliary condenser 25 is mounted in parallel with the head condenser 8 and therefore constitutes a second head condenser of the column. The production of the column is thereby simplified, but, on the other hand, it is necessary to slightly increase the pressure of the rich liquid vaporized and therefore the pressure of the incoming air.

Claims (10)

  1. Process for producing a major proportion of nitrogen and a minor proportion of oxygen by distilling a gaseous mixture, in particular air, of the type in which :
    - the gaseous mixture is cooled in a heat exchange line (3) and then introduced at an intermediate level of a distillation column (4) operating at a medium pressure and provided with a head condenser (8) and a vessel reboiler (9);
    - liquid withdrawn from the column below the point of introduction of the gaseous mixture is, after expansion (in 19) to a low pressure lower than the medium pressure, vaporized in the head condenser (8);
    - gaseous nitrogen (11) is withdrawn at the column head and reheated and, compressed in part to a high pressure greater than the medium pressure, cooled and introduced into the reboiler (9) to be condensed there; and
    - at least part of the liquid nitrogen thus obtained is expanded (in 15) to the medium pressure and, possibly after purification, introduced at the head of the column,
    characterized in that :
    - the said liquid (16) is withdrawn at a level intermediate between the level at which air is injected and the reboiler and reheated in the exchange line (3) before being evacuated as a residual gas, and liquid from the vessel of the column is vaporized and recovered as a minor product consisting substantially of oxygen.
  2. Process according to claim 1, characterized in that liquid in the vessel intended to constitute the said minor product is vaporized by the reboiler (9) and withdrawn in gaseous form immediately above the latter.
  3. Process according to claim 1, characterized in that the liquid in the vessel intended to constitute the said minor product is expanded (in 24) and then vaporized in an auxiliary condenser (25) provided in the upper part of the column (4).
  4. Process according to claim 3, characterized in that the auxiliary condenser (25) is provided below the head condenser (8).
  5. Process according to claim 3, characterized in that the auxiliary condenser (25) is provided in parallel with the head condenser (8), the said liquid in the vessel being expanded (in 24) to a pressure lower than the said low pressure.
  6. Installation for producing a major proportion of nitrogen and a minor proportion of oxygen by distilling a gaseous mixture, in particular air, of the type comprising :
    - a distillation column (4) operating at a medium pressure and provided with a head condenser (8) and a vessel reboiler (9);
    - means (1, 2, 3, 5) for compressing, purifying and cooling the gaseous mixture and introducing it at an intermediate level of the column;
    - means (16) for withdrawing a liquid at a level of the column lower than the level at which the gaseous mixture is introduced, means (19) for expanding this liquid to a low pressure and means for introducing it with a view to its vaporization in the head condenser (8);
    - means (11) for withdrawing nitrogen at the head of the column, and means (6, 3, 7, 14) for reheating, compressing to a high pressure, cooling and introducing part of this nitrogen into the reboiler (9); and
    - means (15) for expanding to the medium pressure at least part of the liquid nitrogen coming from the reboiler and for introducing it at the head of the column;
    characterized in that :
    - the level at which the said liquid is withdrawn is intermediate between the level at which the gaseous mixture is introduced and the reboiler (9); and
    - means (9, 20, 21; 23 to 26) are provided for vaporizing liquid from the vessel of the column and for recovering the resulting gas, consisting substantially of oxygen, as the minor product of the installation.
  7. Installation according to claim 6, characterized in that the column (4) comprises a pipe (20) for withdrawing the said minor product immediately above the reboiler (9).
  8. Installation according to claim 6, characterized in that the column (4) comprises an auxiliary condenser (25) fed by the said liquid from the vessel via a pipe (23) provided with an expansion valve (24).
  9. Installation according to claim 8, characterized in that the auxiliary condenser (25) is mounted at a level lower than that of the head condenser (8).
  10. Installation according to claim 8, characterized in that the auxiliary condenser (25) is mounted in parallel with the head condenser (8).
EP93402421A 1992-10-27 1993-10-04 Process and installation for the production of nitrogen and oxygen Expired - Lifetime EP0595673B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9212759 1992-10-27
FR9212759A FR2697325B1 (en) 1992-10-27 1992-10-27 Process and installation for the production of nitrogen and oxygen.

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EP0595673A1 EP0595673A1 (en) 1994-05-04
EP0595673B1 true EP0595673B1 (en) 1996-12-04

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EP (1) EP0595673B1 (en)
JP (1) JP3436398B2 (en)
CA (1) CA2109148A1 (en)
DE (1) DE69306362T2 (en)
ES (1) ES2095019T3 (en)
FR (1) FR2697325B1 (en)

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DE10157544A1 (en) * 2001-11-23 2003-06-12 Messer Ags Gmbh Method and device for producing nitrogen from air

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US5706675A (en) * 1995-08-18 1998-01-13 G & A Associates High efficiency oxygen/air separation system
US5832748A (en) * 1996-03-19 1998-11-10 Praxair Technology, Inc. Single column cryogenic rectification system for lower purity oxygen production
US5761927A (en) * 1997-04-29 1998-06-09 Air Products And Chemicals, Inc. Process to produce nitrogen using a double column and three reboiler/condensers
FR2767317B1 (en) * 1997-08-14 1999-09-10 Air Liquide PROCESS FOR CONVERTING A FLOW CONTAINING HYDROCARBONS BY PARTIAL OXIDATION
US6000239A (en) * 1998-07-10 1999-12-14 Praxair Technology, Inc. Cryogenic air separation system with high ratio turboexpansion
FR2782544B1 (en) * 1998-08-19 2005-07-08 Air Liquide PUMP FOR A CRYOGENIC LIQUID AND PUMP GROUP AND DISTILLATION COLUMN EQUIPPED WITH SUCH A PUMP
CN113686099B (en) * 2021-08-09 2022-08-09 北京科技大学 Material recovery method based on internal compression air separation energy storage device

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BE680216A (en) * 1965-05-07 1966-10-28
FR2461906A1 (en) * 1979-07-20 1981-02-06 Air Liquide CRYOGENIC AIR SEPARATION METHOD AND INSTALLATION WITH OXYGEN PRODUCTION AT HIGH PRESSURE
DE3035844A1 (en) * 1980-09-23 1982-05-06 Linde Ag, 6200 Wiesbaden Medium-purity oxygen prodn. - uses part of nitrogen current to counter cooling losses and heats remainder
DE3738559A1 (en) * 1987-11-13 1989-05-24 Linde Ag METHOD FOR AIR DISASSEMBLY BY DEEP TEMPERATURE RECTIFICATION
FR2651035A1 (en) * 1989-08-18 1991-02-22 Air Liquide PROCESS FOR THE PRODUCTION OF NITROGEN BY DISTILLATION
US5049173A (en) * 1990-03-06 1991-09-17 Air Products And Chemicals, Inc. Production of ultra-high purity oxygen from cryogenic air separation plants

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DE10157544A1 (en) * 2001-11-23 2003-06-12 Messer Ags Gmbh Method and device for producing nitrogen from air

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US5404725A (en) 1995-04-11
DE69306362T2 (en) 1997-06-26
FR2697325B1 (en) 1994-12-23
ES2095019T3 (en) 1997-02-01
FR2697325A1 (en) 1994-04-29
CA2109148A1 (en) 1994-04-28
DE69306362D1 (en) 1997-01-16
JPH06207776A (en) 1994-07-26
JP3436398B2 (en) 2003-08-11
EP0595673A1 (en) 1994-05-04

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