EP0507649B1 - Method for the evaporation of a liquid, heat exchanger for carrying out the method, and use in an air distillation plant with a double column - Google Patents

Method for the evaporation of a liquid, heat exchanger for carrying out the method, and use in an air distillation plant with a double column Download PDF

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Publication number
EP0507649B1
EP0507649B1 EP92400773A EP92400773A EP0507649B1 EP 0507649 B1 EP0507649 B1 EP 0507649B1 EP 92400773 A EP92400773 A EP 92400773A EP 92400773 A EP92400773 A EP 92400773A EP 0507649 B1 EP0507649 B1 EP 0507649B1
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EP
European Patent Office
Prior art keywords
passages
liquid
exchanger
end part
column
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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.)
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EP92400773A
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German (de)
French (fr)
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EP0507649A1 (en
Inventor
Christine Muller
Frédéric Rousseau
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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
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D9/0062—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for one heat-exchange medium being formed by spaced plates with inserted elements
    • F28D9/0068—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for one heat-exchange medium being formed by spaced plates with inserted elements with means for changing flow direction of one heat exchange medium, e.g. using deflecting zones
    • 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
    • F25J5/00—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants
    • F25J5/002—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants for continuously recuperating cold, i.e. in a so-called recuperative heat exchanger
    • 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
    • F25J5/00—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants
    • F25J5/002—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants for continuously recuperating cold, i.e. in a so-called recuperative heat exchanger
    • F25J5/005—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants for continuously recuperating cold, i.e. in a so-called recuperative heat exchanger in a reboiler-condenser, e.g. within a 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
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/02—Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
    • 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
    • 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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/32—Details on header or distribution passages of heat exchangers, e.g. of reboiler-condenser or plate heat exchangers
    • 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
    • Y10S62/902—Apparatus
    • Y10S62/903—Heat exchange structure

Definitions

  • the present invention relates to a method of vaporizing a liquid in first passages, or vaporization passages, substantially vertical, open at the top and bottom, of a plate heat exchanger, by heat exchange with a fluid.
  • a process of this kind is known from FR-A-2,486,627.
  • cryogenic liquids in particular liquid oxygen in the tanks of low pressure columns of double column air distillation installations.
  • Plate heat exchangers widely used in air distillation installations, include an assembly of many vertical rectangular aluminum plates defining between them a large number of large flat passages. Waves, serving as spacers between the plates and thermal fins, are arranged between the plates. The edges of the passages are closed by spacer bars, and interruptions of these allow the introduction of fluids into the exchanger and their extraction, via semi-cylindrical inlet and outlet boxes fixed opposite these interruptions.
  • bath vaporizers have completely open vaporization passages at the top and bottom. They are commonly used, for example, to vaporize liquid oxygen by condensing medium pressure nitrogen in the tanks of the low pressure columns of the double air distillation columns.
  • Such a bath vaporizer is immersed in the bath of the fluid to be vaporized (oxygen in the case of a double column).
  • the circulation of this fluid is by thermosiphon effect.
  • the total flow rate circulating in the vaporization passages depends, for a given exchanger and heat flow, on the value of the submergence, which is the ratio of the immersion height of the exchanger in the liquid bath to the height of the percent exchanger. This flow decreases when the submergence decreases, and the recirculation (ratio of the liquid flow at the outlet to the vaporized flow) is canceled for too low submergence values, causing drying in the upper part of the vaporizer.
  • the invention aims to allow a reduction in submergence without drying out of the upper part of the spray passages.
  • At least one auxiliary fluid is circulated in the lower end part of the exchanger, in heat exchange relation with the lower end part of the first passages. hotter than the main circulating fluid in order to generate said additional gas.
  • the invention also relates to a heat exchanger of the plate type, comprising first passages, or vaporization passages, substantially vertical, open at the top and bottom and second passages for circulation of a main circulating fluid which comprises gas generation means in the lower end part of the first passages, characterized in that the generating means comprise or consist of at least one circulation compartment of at least one auxiliary fluid hotter than the main circulating fluid extending the lower end part of the second passages, opposite that of the first passages.
  • the invention also relates to an air distillation installation with double column which comprises a main evaporator-condenser constituted by a heat exchanger as defined above, arranged in the tank of the low pressure column of the double column , and means for circulating medium pressure nitrogen in said second passages.
  • FIG. 1 shows schematically a heat exchanger 1 of the brazed plate type, constituting the main evaporator-condenser of a double air distillation column and mounted in the tank 2 of the low pressure column 40 surmounting the column medium pressure 50 of this double column.
  • the exchanger 1 of generally parallelepiped shape, consists of a large number of vertical rectangular plates 3 of aluminum delimiting between them two series of passages, which are for example alternated: first passages 4, or oxygen vaporization passages liquid, and second passages 5, or nitrogen condensation passages.
  • Each passage 4 ( Figure 2) is open at the top and bottom and closed on each side, over its entire height, by spacer bars 4A. It contains a wave 6 with vertical generators, in particular perforated, which extends over its entire height and which serves both as a spacer and as a thermal fin.
  • Each passage 5 (FIG. 3) has, over most of its height, lateral spacer bars 5A for closing and a wave 7 with vertical generators similar to waves 6. It has a zone 8 for the entry of nitrogen gas at its end. upper and a liquid nitrogen outlet zone 9 at its lower end. Zone 8 is closed at the top and on one side 10 by spacer bars 8A and is open on the other side, by an entrance window 11. It contains a distribution wave comprising a first wave 12 with descending oblique generators , leading directly to the upper end of the wave 7, over the entire width (that is to say the horizontal dimension) of the passage 5.
  • the outlet zone is closed at the bottom and on one side 14 by spacer bars 9A and open on the other side on a exit window 15. It contains an oblique wave 16 onto which the wave 7 opens directly, over the entire width of the passage 5, and a horizontal wave 17 opening onto the window 15.
  • the plates, waves and spacer bars have smooth surfaces, free from roughness or cavities. All of the plates, waves and spacer bars are secured in a sealed manner by brazing in the oven, then semi-cylindrical boxes 18, 19 for nitrogen inlet and outlet are fixed laterally by welding on the exchanger , opposite windows 11 and 15. These boxes are connected respectively to the top of the medium pressure column (not shown) of the double column by pipes 20, 21.
  • Perforated ramps 22 connected to an oxygen source are arranged under the exchanger 1 in the column tank 2, and preferably just below each of the vaporization passages 4, with perforations distributed throughout the width of it.
  • the wave 6 can, in each passage 4, be stopped at a small distance from the bottom of the exchanger, and the ramp 22 be housed in the space thus released at the lower end of the passage.
  • the exchanger 1 is partially immersed in the liquid oxygen bath 23 formed in the column tank 2.
  • the nitrogen gas under medium pressure of approximately 6 ⁇ 10 5 absolute Pa circulates in the passages 5, via the box 18, the waves 12, 13, 7, 16 and 17, by condensing, and in a liquid spring via the box 19.
  • this nitrogen causes the vaporization of the liquid oxygen contained in the passages 4, and oxygen circulates by thermosyphon effect from bottom to top in these passages, containing an increasing proportion of gases.
  • Two-phase liquid oxygen / gaseous oxygen mixture exits from the top of the passages 4 and falls back into the bath 23, as shown diagrammatically by the arrows in FIG. 1, where the downward circulation of the 'nitrogen.
  • the upward flow of oxygen is permanently two-phase from the lower end of these passages, which improves the 'heat exchange between oxygen and nitrogen.
  • recirculation is increased and as a result, reduced submergence can be adopted without risk of drying out the area.
  • the performance of the vaporizer-condenser is significantly improved, and the temperature of the circulating nitrogen gas and therefore the operating pressure (that is to say the medium pressure) of the air distillation installation.
  • the flow of gaseous oxygen introduced via the ramps 22 is of the order of 2 to 4% of the flow of vaporized oxygen.
  • the additional gaseous oxygen (relative to that generated by heating with medium pressure nitrogen) is generated in situ at the lower end of the passages 4.
  • the ramps 22 are deleted, and the passages 5 of Figure 3 are slightly shortened down, that is to say they are closed down by a bar spacer 24 located at a small distance from the lower end of the exchanger.
  • a compartment 25 closed at the bottom by a spacer strip 26, open on both sides and containing over its entire length a wave 27 with horizontal generatrices.
  • compartment 25 can be replaced by several superimposed compartments, thus allowing the use of several auxiliary fluids.
  • the compartment 25 can be subdivided so as to constitute several superimposed passes, connected in series, to increase the speed of passage of the auxiliary fluid and, thus, improve its heat exchange coefficient.
  • FIGS. 4 and 5 can be used to also inject gaseous oxygen into the vaporization passages 4, as in FIGS. 1 to 3.
  • the gaseous oxygen is introduced into the compartments 25 via the box 28, the box 29 is replaced by closing bars, and the plates 3 are perforated along the compartments 25 to allow the passage of gaseous oxygen from these compartments in the vaporization passages 4. In this case, it is best to remove the waves 27.

Description

La présente invention est relative à un procédé de vaporisation d'un liquide dans des premiers passages, ou passages de vaporisation, sensiblement verticaux, ouverts en haut et en bas, d'un échangeur de chaleur à plaques, par échange de chaleur avec un fluide calorigène principal circulant de haut en bas dans des seconds passages de l'échangeur dans lequel on génère en continu du gaz additionnel dans la partie d'extrémité inférieure desdits premiers passages. Un procédé de ce genre est connu de FR-A-2.486.627.The present invention relates to a method of vaporizing a liquid in first passages, or vaporization passages, substantially vertical, open at the top and bottom, of a plate heat exchanger, by heat exchange with a fluid. main circulating circulating from top to bottom in second passages of the exchanger in which additional gas is continuously generated in the lower end part of said first passages. A process of this kind is known from FR-A-2,486,627.

Elle s'applique notamment à la vaporisation des liquides cryogéniques, en particulier de l'oxygène liquide en cuve des colonnes basse pression des installations de distillation d'air à double colonne.It applies in particular to the vaporization of cryogenic liquids, in particular liquid oxygen in the tanks of low pressure columns of double column air distillation installations.

Les échangeurs de chaleur à plaques, largement utilisés dans les installations de distillation d'air, comprennent un assemblage de nombreuses plaques rectangulaires verticales en aluminium définissant entre elles un grand nombre de passages plats de grandes dimensions. Des ondes, servant d'entretoises entre les plaques et d'ailettes thermiques, sont disposées entre les plaques. Les bords des passages sont fermés par des barrettes-entretoises, et des interruptions de celles-ci permettent l'introduction des fluides dans l'échangeur et leur extraction, via des boîtes d'entrée et de sortie semi-cylindriques fixées en regard de ces interruptions.Plate heat exchangers, widely used in air distillation installations, include an assembly of many vertical rectangular aluminum plates defining between them a large number of large flat passages. Waves, serving as spacers between the plates and thermal fins, are arranged between the plates. The edges of the passages are closed by spacer bars, and interruptions of these allow the introduction of fluids into the exchanger and their extraction, via semi-cylindrical inlet and outlet boxes fixed opposite these interruptions.

Parmi ces échangeurs, certains, dits "vaporiseurs à bain", comportent des passages de vaporisation complètement ouverts en haut et en bas. Ils sont couramment utilisés, par exemple, pour vaporiser l'oxygène liquide par condensation d'azote moyenne pression en cuve des colonnes basse pression des doubles colonnes de distillation d'air.Among these exchangers, some, called "bath vaporizers", have completely open vaporization passages at the top and bottom. They are commonly used, for example, to vaporize liquid oxygen by condensing medium pressure nitrogen in the tanks of the low pressure columns of the double air distillation columns.

Un tel vaporiseur à bain est immergé dans le bain du fluide à vaporiser (de l'oxygène pour le cas d'une double colonne). La circulation de ce fluide se fait par effet thermosiphon.Such a bath vaporizer is immersed in the bath of the fluid to be vaporized (oxygen in the case of a double column). The circulation of this fluid is by thermosiphon effect.

Le débit total circulant dans les passages de vaporisation dépend, pour un échangeur et un flux de chaleur donnés, de la valeur de la submergence, qui est le rapport de la hauteur d'immersion de l'échangeur dans le bain de liquide à la hauteur de l'échangeur en pourcents. Ce débit diminue lorsque la submergence diminue, et la recirculation (rapport du débit liquide en sortie au débit vaporisé) s'annule pour les valeurs de submergence trop faibles, entraînant un assèchement dans la partie haute du vaporiseur.The total flow rate circulating in the vaporization passages depends, for a given exchanger and heat flow, on the value of the submergence, which is the ratio of the immersion height of the exchanger in the liquid bath to the height of the percent exchanger. This flow decreases when the submergence decreases, and the recirculation (ratio of the liquid flow at the outlet to the vaporized flow) is canceled for too low submergence values, causing drying in the upper part of the vaporizer.

Dans certains cas, et notamment dans les vaporiseurs d'oxygène précités, un tel fonctionnement à sec n'est pas permis, pour des questions de sécurité. En effet, il existe un risque de dépôt et de concentration d'hydrocarbures qui peuvent réagir de façon explosive avec l'oxygène. On se voit donc contraint de travailler à des submergences relativement élevées, généralement de l'ordre de 70 à 80 %.In certain cases, and in particular in the abovementioned oxygen vaporizers, such dry operation is not permitted, for safety reasons. Indeed, there is a risk of deposition and concentration of hydrocarbons which can react explosively with oxygen. We are therefore forced to work at relatively high submergences, generally of the order of 70 to 80%.

Ceci est pénalisant du point de vue de la performance de l'échangeur, car la hauteur hydrostatique du bain de liquide entraîne un sous-refroidissement de ce liquide en bas de l'échangeur, ce sous-refroidissement atteignant par exemple 0,8°C pour une hauteur d'oxygène liquide de 1 mètre dans une colonne basse pression fonctionnant sous 1,3 bar absolu. La partie basse du vaporiseur est donc utilisée pour réchauffer ce liquide et l'amener à son point d'ébullition, et cette zone peut atteindre une fraction importante de la hauteur du vaporiseur (1/3 à 1/4 pour une submergence de 100 %).This is penalizing from the point of view of the performance of the exchanger, because the hydrostatic height of the liquid bath causes this liquid to be sub-cooled at the bottom of the exchanger, this sub-cooling reaching for example 0.8 ° C. for a height of liquid oxygen of 1 meter in a low pressure column operating at 1.3 bar absolute. The lower part of the vaporizer is therefore used to heat this liquid and bring it to its boiling point, and this area can reach a significant fraction of the height of the vaporizer (1/3 to 1/4 for 100% submergence ).

Dans ces conditions, il est difficile de faire fonctionner un vaporiseur d'oxygène à bain avec un faible écart de température inférieur à 1°C entre l'oxygène et l'azote moyenne pression, sauf à réduire la hauteur du vaporiseur et à installer en cuve de colonne des échangeurs placés dans des bains superposés. Cette solution a déjà été mise en oeuvre sur certains appareils, mais elle est coûteuse en investissement.Under these conditions, it is difficult to operate an oxygen vaporizer in a bath with a small temperature difference of less than 1 ° C between oxygen and medium pressure nitrogen, except to reduce the height of the vaporizer and to install in column tank of the exchangers placed in superimposed baths. This solution has already been implemented on certain devices, but it is costly in investment.

L'invention a pour but de permettre une réduction de la submergence sans assèchement de la partie supérieure des passages de vaporisation.The invention aims to allow a reduction in submergence without drying out of the upper part of the spray passages.

A cet effet, selon une caractéristique de l'invention, on fait circuler, dans la partie d'extrémité inférieure de l'échangeur, en relation d'échange thermique avec la partie d'extrémité inférieure des premiers passages, au moins un fluide auxiliaire plus chaud que le fluide calorigène principal afin de générer ledit gaz additionnel.To this end, according to a characteristic of the invention, at least one auxiliary fluid is circulated in the lower end part of the exchanger, in heat exchange relation with the lower end part of the first passages. hotter than the main circulating fluid in order to generate said additional gas.

Suivant des modes particuliers de réalisation de l'invention :

  • on injecte en continu un flux du gaz, provenant d'une source de gaz extérieure à l'échangeur, dans le liquide contenu dans ladite partie d'extrémité inférieure ;
  • pour la vaporisation d'un corps pur à l'état liquide, ledit gaz est constitué par le même corps pur à l'état gazeux ;
  • pour la vaporisation d'oxygène liquide dans le vaporiseur-condenseur principal d'une installation de distillation d'air à double colonne, le fluide auxiliaire chaud est du liquide riche provenant de la cuve de la colonne moyenne pression de la double colonne, de l'air moyenne pression ou de l'air basse pression issu d'une turbine de détente de l'installation.
According to particular embodiments of the invention:
  • a stream of gas, coming from a source of gas external to the exchanger, is continuously injected into the liquid contained in said lower end part;
  • for the vaporization of a pure body in the liquid state, said gas consists of the same pure body in the gaseous state;
  • for the vaporization of liquid oxygen in the main evaporator-condenser of a double column air distillation installation, the hot auxiliary fluid is rich liquid coming from the tank of the medium pressure column of the double column, from the medium pressure air or low pressure air from an expansion turbine in the installation.

L'invention a également pour objet un échangeur de chaleur du type à plaques, comprenant des premiers passages, ou passages de vaporisation, sensiblement verticaux, ouverts en haut et en bas et des seconds passages de circulation d'un fluide calorigène principal qui comporte des moyens de génération de gaz dans la partie d'extrémité inférieure des premiers passages, caractérisé en ce que les moyens générateurs comprennent ou sont constitués par au moins un compartiment de circulation d'au moins un fluide auxiliaire plus chaud que le fluide calorigène principal prolongeant la partie d'extrémité inférieure des seconds passages, en regard de celle des premiers passages.The invention also relates to a heat exchanger of the plate type, comprising first passages, or vaporization passages, substantially vertical, open at the top and bottom and second passages for circulation of a main circulating fluid which comprises gas generation means in the lower end part of the first passages, characterized in that the generating means comprise or consist of at least one circulation compartment of at least one auxiliary fluid hotter than the main circulating fluid extending the lower end part of the second passages, opposite that of the first passages.

L'invention a encore pour objet une installation de distillation d'air à double colonne qui comprend un vaporiseur-condenseur principal constitué par un échangeur de chaleur tel que défini ci-dessus, disposé dans la cuve de la colonne basse pression de la double colonne, et des moyens pour faire circuler de l'azote moyenne pression dans lesdits seconds passages.The invention also relates to an air distillation installation with double column which comprises a main evaporator-condenser constituted by a heat exchanger as defined above, arranged in the tank of the low pressure column of the double column , and means for circulating medium pressure nitrogen in said second passages.

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

  • la figure 1 est une vue schématique en élévation d'un échangeur de chaleur permettant la mise en oeuvre du procédé conforme à l'invention ; ---
  • la figure 2 est une vue de cet échangeur, prise en coupe verticale dans un passage de vaporisation ;
  • la figure 3 est une vue du même échangeur, prise en coupe verticale dans un passage de circulation de fluide calorigène ;
  • la figure 4 est une vue schématique en élévation d'un échangeur de chaleur conforme à l'invention ; et
  • la figure 5 est une vue analogue à la figure 3 de l'échangeur de la figure 4.
Examples of implementation of the invention will now be described with reference to the accompanying drawings, in which:
  • Figure 1 is a schematic elevational view of a heat exchanger for implementing the method according to the invention; ---
  • Figure 2 is a view of this exchanger, taken in vertical section in a spray passage;
  • Figure 3 is a view of the same exchanger, taken in vertical section in a circulating fluid circulation passage;
  • Figure 4 is a schematic elevational view of a heat exchanger according to the invention; and
  • FIG. 5 is a view similar to FIG. 3 of the exchanger of FIG. 4.

On a représenté schématiquement à la figure 1 un échangeur de chaleur 1 du type à plaques brasées, constituant le vaporiseur-condenseur principal d'une double colonne de distillation d'air et monté dans la cuve 2 de la colonne basse pression 40 surmontant la colonne moyenne pression 50 de cette double colonne.FIG. 1 shows schematically a heat exchanger 1 of the brazed plate type, constituting the main evaporator-condenser of a double air distillation column and mounted in the tank 2 of the low pressure column 40 surmounting the column medium pressure 50 of this double column.

L'échangeur 1, de forme générale parallélépipédique, est constitué d'un grand nombre de plaques rectangulaires verticales 3 en aluminium délimitant entre elles deux séries de passages, qui sont par exemple alternés : des premiers passages 4, ou passages de vaporisation d'oxygène liquide, et des seconds passages 5, ou passages de condensation d'azote.The exchanger 1, of generally parallelepiped shape, consists of a large number of vertical rectangular plates 3 of aluminum delimiting between them two series of passages, which are for example alternated: first passages 4, or oxygen vaporization passages liquid, and second passages 5, or nitrogen condensation passages.

Chaque passage 4 (figure 2) est ouvert en haut et en bas et fermé de chaque côté, sur toute sa hauteur, par des barrettes-entretoises 4A. Il contient une onde 6 à génératrices verticales, notamment perforée, qui s'étend sur toute sa hauteur et qui sert à la fois d'entretoise et d'ailette thermique.Each passage 4 (Figure 2) is open at the top and bottom and closed on each side, over its entire height, by spacer bars 4A. It contains a wave 6 with vertical generators, in particular perforated, which extends over its entire height and which serves both as a spacer and as a thermal fin.

Chaque passage 5 (figure 3) comporte sur l'essentiel de sa hauteur des barrettes-entretoises latérales 5A de fermeture et une onde 7 à génératrices verticales analogue aux ondes 6. Il présente une zone 8 d'entrée d'azote gazeux à son extrémité supérieure et une zone 9 de sortie d'azote liquide à son extrémité inférieure. La zone 8 est fermée en haut et sur un côté 10 par des barrettes-entretoises 8A et est ouvert sur l'autre côté, par une fenêtre d'entrée 11. Elle contient une onde de distribution comprenant une première onde 12 à génératrices obliques descendantes, débouchant directement sur l'extrémité supérieure de l'onde 7, sur toute la largeur (c'est-à-dire la dimension horizontale) du passage 5.Each passage 5 (FIG. 3) has, over most of its height, lateral spacer bars 5A for closing and a wave 7 with vertical generators similar to waves 6. It has a zone 8 for the entry of nitrogen gas at its end. upper and a liquid nitrogen outlet zone 9 at its lower end. Zone 8 is closed at the top and on one side 10 by spacer bars 8A and is open on the other side, by an entrance window 11. It contains a distribution wave comprising a first wave 12 with descending oblique generators , leading directly to the upper end of the wave 7, over the entire width (that is to say the horizontal dimension) of the passage 5.

De même, la zone de sortie est fermée en bas et sur un côté 14 par des barrettes-entretoises 9A et ouverte de l'autre côté sur une fenêtre de sortie 15. Elle contient une onde oblique 16 sur laquelle l'onde 7 débouche directement, sur toute la largeur du passage 5, et une onde horizontale 17 débouchant sur la fenêtre 15.Similarly, the outlet zone is closed at the bottom and on one side 14 by spacer bars 9A and open on the other side on a exit window 15. It contains an oblique wave 16 onto which the wave 7 opens directly, over the entire width of the passage 5, and a horizontal wave 17 opening onto the window 15.

Les plaques, ondes et barrettes-entretoises ont des surfaces lisses, exemptes d'aspérités ou de cavités. L'ensemble des plaques, des ondes et des barrettes-entretoises est solidarisé de façon étanche par brasage au four, puis des boîtes semi-cylindriques 18, 19 d'entrée et de sortie d'azote sont fixées latéralement par soudage sur l'échangeur, en regard des fenêtres 11 et 15. Ces boîtes sont reliées respectivement au sommet de la colonne moyenne pression (non représentée) de la double colonne par des conduites 20, 21.The plates, waves and spacer bars have smooth surfaces, free from roughness or cavities. All of the plates, waves and spacer bars are secured in a sealed manner by brazing in the oven, then semi-cylindrical boxes 18, 19 for nitrogen inlet and outlet are fixed laterally by welding on the exchanger , opposite windows 11 and 15. These boxes are connected respectively to the top of the medium pressure column (not shown) of the double column by pipes 20, 21.

Des rampes perforées 22 reliées à une source d'oxygène (non représentée) sont disposées sous l'échangeur 1 dans la cuve de colonne 2, et de préférence juste au-dessous de chacun des passages de vaporisation 4, avec des perforations réparties sur toute la largeur de celui-ci. En variante, comme indiqué en traits mixtes sur la figure 2, l'onde 6 peut, dans chaque passage 4, être arrêtée à une petite distance du bas de l'échangeur, et la rampe 22 être logée dans l'espace ainsi dégagé à l'extrémité inférieure du passage.Perforated ramps 22 connected to an oxygen source (not shown) are arranged under the exchanger 1 in the column tank 2, and preferably just below each of the vaporization passages 4, with perforations distributed throughout the width of it. As a variant, as indicated in dashed lines in FIG. 2, the wave 6 can, in each passage 4, be stopped at a small distance from the bottom of the exchanger, and the ramp 22 be housed in the space thus released at the lower end of the passage.

En fonctionnement, l'échangeur 1 est partiellement immergé dans le bain d'oxygène liquide 23 formé dans la cuve de colonne 2. L'azote gazeux sous la moyenne pression d'environ 6 x 105 Pa absolus circule dans les passages 5, via la boîte 18, les ondes 12, 13, 7, 16 et 17, en se condensant, et en ressort liquide via la boîte 19. En se condensant, cet azote provoque la vaporisation de l'oxygène liquide contenu dans les passages 4, et l'oxygène circule par effet de thermosiphon de bas en haut dans ces passages, en contenant une proportion croissante de gaz. Du mélange diphasique oxygène liquide/oxygène gazeux sort par le haut des passages 4 et retombe dans le bain 23, comme schématisé par les flèches de la figure 1, où l'on a également schématisé par une flèche en traits mixtes la circulation descendante de l'azote.In operation, the exchanger 1 is partially immersed in the liquid oxygen bath 23 formed in the column tank 2. The nitrogen gas under medium pressure of approximately 6 × 10 5 absolute Pa circulates in the passages 5, via the box 18, the waves 12, 13, 7, 16 and 17, by condensing, and in a liquid spring via the box 19. By condensing, this nitrogen causes the vaporization of the liquid oxygen contained in the passages 4, and oxygen circulates by thermosyphon effect from bottom to top in these passages, containing an increasing proportion of gases. Two-phase liquid oxygen / gaseous oxygen mixture exits from the top of the passages 4 and falls back into the bath 23, as shown diagrammatically by the arrows in FIG. 1, where the downward circulation of the 'nitrogen.

Grâce à l'injection en continu d'un flux d'oxygène gazeux au bas des passages 4 par les rampes 22, l'écoulement ascendant de l'oxygène est en permanence diphasique dès l'extrémité inférieure de ces passages, ce qui améliore l'échange thermique entre l'oxygène et l'azote. De plus, la recirculation est accrue et par suite, une submergence réduite peut être adoptée sans risque d'assécher la zone supérieure des passages 4, ce qui résulte finalement en un moindre sous-refroidissement de l'oxygène liquide contenu dans l'échangeur 1. Au total, les performances du vaporiseur-condenseur sont nettement améliorées, et l'on peut réduire la température de l'azote gazeux calorigène et donc la pression de marche (c'est-à-dire la moyenne pression) de l'installation de distillation d'air. Le débit d'oxygène gazeux introduit via les rampes 22 est de l'ordre de 2 à 4 % du débit d'oxygène vaporisé.Thanks to the continuous injection of a gaseous oxygen flow at the bottom of the passages 4 by the ramps 22, the upward flow of oxygen is permanently two-phase from the lower end of these passages, which improves the 'heat exchange between oxygen and nitrogen. In addition, recirculation is increased and as a result, reduced submergence can be adopted without risk of drying out the area. upper passages 4, which ultimately results in less subcooling of the liquid oxygen contained in the exchanger 1. In total, the performance of the vaporizer-condenser is significantly improved, and the temperature of the circulating nitrogen gas and therefore the operating pressure (that is to say the medium pressure) of the air distillation installation. The flow of gaseous oxygen introduced via the ramps 22 is of the order of 2 to 4% of the flow of vaporized oxygen.

Dans le mode de réalisation des figures 4 et 5, avantageux au plan énergétique, l'oxygène gazeux additionnel (par rapport à celui généré par le chauffage à l'azote moyenne pression) est généré in situ à l'extrémité inférieure des passages 4. Ces derniers sont identiques à ceux de la figure 2, les rampes 22 sont supprimées, et les passages 5 de la figure 3 sont légèrement raccourcis vers le bas, c'est-à-dire qu'ils sont fermés vers le bas par une barrette-entretoise 24 située à une petite distance de l'extrémité inférieure de l'échangeur. Au-dessous de cette barrette est délimité un compartiment 25 fermé en bas par une barrette-entretoise 26, ouvert des deux côtés et contenant sur toute sa longueur une onde 27 à génératrices horizontales.In the embodiment of FIGS. 4 and 5, which is advantageous from an energy point of view, the additional gaseous oxygen (relative to that generated by heating with medium pressure nitrogen) is generated in situ at the lower end of the passages 4. These are identical to those of Figure 2, the ramps 22 are deleted, and the passages 5 of Figure 3 are slightly shortened down, that is to say they are closed down by a bar spacer 24 located at a small distance from the lower end of the exchanger. Below this strip is delimited a compartment 25 closed at the bottom by a spacer strip 26, open on both sides and containing over its entire length a wave 27 with horizontal generatrices.

En fonctionnement, un fluide auxiliaire plus chaud que l'azote moyenne pression circule en continu à travers le compartiment 25, dans lequel il entre via une boîte d'entrée 28 et d'où il ressort via une boîte de sortie 29. La température et le débit de ce fluide sont choisis pour créer en permanence un début de vaporisation suffisant de l'oxygène dans cette région. On pourra notamment choisir comme fluide auxiliaire :

  • du "liquide riche" (air enrichi en oxygène) soutiré en cuve de la colonne moyenne pression, et qui sera sous-refroidi dans les compartiments 25 ;
  • de l'air moyenne pression, qui sera liquéfié dans ces compartiments ; ou
  • de l'air basse pression sortant d'une turbine de détente et destiné à être insufflé dans la colonne basse pression, lorsque la température de cet air à la sortie de la turbine est suffisante.
In operation, an auxiliary fluid hotter than medium pressure nitrogen circulates continuously through the compartment 25, into which it enters via an inlet box 28 and from which it exits via an outlet box 29. The temperature and the flow of this fluid are chosen to permanently create a sufficient start of vaporization of the oxygen in this region. We can notably choose as auxiliary fluid:
  • "rich liquid" (oxygen-enriched air) withdrawn from the bottom of the medium pressure column, and which will be sub-cooled in the compartments 25;
  • medium pressure air, which will be liquefied in these compartments; or
  • low pressure air leaving an expansion turbine and intended to be blown into the low pressure column, when the temperature of this air at the outlet of the turbine is sufficient.

En variante, le compartiment 25 peut être remplacé par plusieurs compartiments superposés, permettant ainsi d'utiliser plusieurs fluides auxiliaires.Alternatively, the compartment 25 can be replaced by several superimposed compartments, thus allowing the use of several auxiliary fluids.

En variante également, le compartiment 25 peut être subdivisé de façon à constituer plusieurs passes superposées, reliées en série, pour augmenter la vitesse de passage du fluide auxiliaire et, ainsi, améliorer son coefficient d'échange thermique.Also in a variant, the compartment 25 can be subdivided so as to constitute several superimposed passes, connected in series, to increase the speed of passage of the auxiliary fluid and, thus, improve its heat exchange coefficient.

En variante encore, la configuration des figures 4 et 5 peut être utilisée pour également injecter de l'oxygène gazeux dans les passages de vaporisation 4, comme aux figures 1 à 3. Pour cela, l'oxygène gazeux est introduit dans les compartiments 25 via la boîte 28, la boîte 29 est remplacée par des barrettes de fermeture, et les plaques 3 sont perforées le long des compartiments 25 pour permettre le passage de l'oxygène gazeux de ces compartiments dans les passages de vaporisation 4. Dans ce cas, il est préférable de supprimer les ondes 27.In another variant, the configuration of FIGS. 4 and 5 can be used to also inject gaseous oxygen into the vaporization passages 4, as in FIGS. 1 to 3. For this, the gaseous oxygen is introduced into the compartments 25 via the box 28, the box 29 is replaced by closing bars, and the plates 3 are perforated along the compartments 25 to allow the passage of gaseous oxygen from these compartments in the vaporization passages 4. In this case, it is best to remove the waves 27.

Claims (7)

  1. Process for vaporizing a liquid in the first passages (4), or vaporization passages, which are substantially vertical and open at the top and bottom, of a plate heat exchanger (1), by heat exchange with a main calorigenic fluid circulating downwards in the second passages (5) of the exchanger, wherein additional gas is continuously generated in the lower end part of the said first passages (4), characterized in that at least one auxiliary fluid which is warmer than the main calorigenic fluid is circulated in the lower end part of the exchanger (1), in a heat exchange relationship with the lower end part of the first passages (4), so as to generate the said additional gas.
  2. Process according to claim 1, characterized in that a stream of gas, derived from a gas source external to the exchanger (1), is injected into the liquid contained in the said lower end part.
  3. Process according to claim 1 or 2, for vaporizing a pure body in the liquid state, characterized in that the said additional gas consists of the same pure body in the gaseous state.
  4. Process according to one of claim 1 to 3, for the vaporization of liquid oxygen in the main vaporiser-condenser of a double column air distillation plant, characterized in that the said auxiliary fluid is rich liquid derived from the bottom of the medium pressure column of the double column, medium pressure air, or low pressure air, coming from an expansion turbine of the plant.
  5. Heat exchanger of the plate type, comprising first passages (4), or vaporization passages, which are substantially vertical and open at the top and bottom, and second passages (5) for circulating a main calorigenic fluid which comprises means (22; 25) for generating gas in the lower end part of the said first passages (4), characterized in that the generating means comprises or consists of a compartment (25), extending the lower end part of the second passages (5) opposite that of the first passages (4), for circulating at least one auxiliary fluid which is warmer than the main calorigenic fluid.
  6. Heat exchanger according to claim 5, wherein the compartment (25) is subdivided so as to constitute several superimposed passes, connected in series.
  7. Plant with a double column for distilling air, characterized in that it comprises a main vaporizer-condenser consisting of a heat exchanger (1) according to claim 5, situated in the bottom (2) of the low pressure column of the double column, and means (28; 29) for circulating rich liquid in the compartment (25) derived from the bottom of the medium pressure column of the double column, medium pressure air, or low pressure air coming from an expansion turbine of the plant.
EP92400773A 1991-04-03 1992-03-23 Method for the evaporation of a liquid, heat exchanger for carrying out the method, and use in an air distillation plant with a double column Expired - Lifetime EP0507649B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9104013A FR2674947B1 (en) 1991-04-03 1991-04-03 PROCESS FOR VAPORIZATION OF A LIQUID, HEAT EXCHANGER FOR ITS IMPLEMENTATION, AND APPLICATION TO A DOUBLE COLUMN AIR DISTILLATION SYSTEM.
FR9104013 1991-04-03

Publications (2)

Publication Number Publication Date
EP0507649A1 EP0507649A1 (en) 1992-10-07
EP0507649B1 true EP0507649B1 (en) 1997-04-23

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US (1) US5205351A (en)
EP (1) EP0507649B1 (en)
JP (1) JPH05187769A (en)
CA (1) CA2064530A1 (en)
DE (1) DE69219193D1 (en)
FR (1) FR2674947B1 (en)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI100209B (en) * 1994-09-27 1997-10-15 Hadwaco Tech Oy Heat
DE19605500C1 (en) * 1996-02-14 1997-04-17 Linde Ag Liquid oxygen generator process assembly
US5775129A (en) * 1997-03-13 1998-07-07 The Boc Group, Inc. Heat exchanger
CN1154831C (en) * 1998-01-30 2004-06-23 林德股份公司 Method and device for evaporating liquid exygen
US6874569B2 (en) 2000-12-29 2005-04-05 Visteon Global Technologies, Inc. Downflow condenser
DE10201832A1 (en) * 2002-01-18 2003-07-31 Linde Ag Plate heat exchanger
US7188492B2 (en) * 2002-01-18 2007-03-13 Linde Aktiengesellschaft Plate heat exchanger
US7266976B2 (en) * 2004-10-25 2007-09-11 Conocophillips Company Vertical heat exchanger configuration for LNG facility
CN102654375A (en) * 2012-04-20 2012-09-05 苏州制氧机有限责任公司 Plate-fin heat exchanger air pumping device in main heat exchanger
FR3069918B1 (en) 2017-08-04 2020-01-17 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude HEAT EXCHANGER COMPRISING A MULTI-CHANNEL DISTRIBUTION ELEMENT

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3590909A (en) * 1969-10-29 1971-07-06 Trane Co Oxygen boiler
NL7110313A (en) * 1971-07-27 1973-01-30
CH606961A5 (en) * 1976-04-13 1978-11-30 Schnyder Edy Ag
GB2084308B (en) * 1980-07-14 1983-11-30 Cryoplants Ltd Revapourising liquefied gas
US4715433A (en) * 1986-06-09 1987-12-29 Air Products And Chemicals, Inc. Reboiler-condenser with doubly-enhanced plates

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US5205351A (en) 1993-04-27
JPH05187769A (en) 1993-07-27
DE69219193D1 (en) 1997-05-28
CA2064530A1 (en) 1992-10-04
EP0507649A1 (en) 1992-10-07
FR2674947A1 (en) 1992-10-09
FR2674947B1 (en) 1998-06-05

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