EP0559117B1 - Process and apparatus for separating a gas mixture - Google Patents

Process and apparatus for separating a gas mixture Download PDF

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Publication number
EP0559117B1
EP0559117B1 EP93103226A EP93103226A EP0559117B1 EP 0559117 B1 EP0559117 B1 EP 0559117B1 EP 93103226 A EP93103226 A EP 93103226A EP 93103226 A EP93103226 A EP 93103226A EP 0559117 B1 EP0559117 B1 EP 0559117B1
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EP
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Prior art keywords
fraction
evaporator
condenser
line
boiling
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Expired - Lifetime
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EP93103226A
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German (de)
French (fr)
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EP0559117A1 (en
Inventor
Horst Dipl.-Ing. Corduan
Werner Dipl.-Ing. Skolaude
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Linde GmbH
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Linde GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/044—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
    • 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/40—Processes or apparatus involving steps for recycling of process streams the recycled stream being air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen
    • 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

Definitions

  • the invention relates to a process for the decomposition of a gas mixture, in particular air, in which a product enriched with lower-boiling components, in particular nitrogen, is obtained, a lower-boiling fraction from the upper region of a rectification column in a condenser-evaporator in indirect heat exchange with an evaporating one heavy-boiling fraction is at least partially condensed, and an apparatus for performing this method.
  • the invention has for its object to make the method of the type mentioned economically more economical, in particular by improving the heat exchange process on the condenser-evaporator.
  • the heavy-boiling fraction is fed a further fraction before the indirect heat exchange, the has a lower proportion of heavy- boiling components than the heavy-boiling fraction.
  • the throughput on the evaporation side of the condenser-evaporator can be increased as an alternative or in addition to an increased throughput of the heavy-boiling fraction by feeding in a lower-boiling fraction.
  • a particularly high throughput of heavy-boiling fraction means an additional load on the rectification column, since liquid condenses at the top of the column and flows back down through the column through the trays or other mass transfer elements (e.g. packing elements or ordered packings), before being removed as a heavy-boiling fraction to be able to.
  • the additional fraction used as additional refrigerant does not first have to be condensed at the top of the column and passed through practically the entire column. If, according to the invention, the mixing of the heavy-boiling fraction with the further fraction poorer in heavy- boiling components is accepted, this fraction can in principle be removed at any point in the process without loading the column.
  • the boiling fraction increases due to the increase in horrid Shares of the vapor pressure on the evaporation side of the condenser-evaporator (at constant evaporation temperature). Taking advantage of this effect, the pressure of the heavy-boiling fraction and subsequently the entire process pressure can be reduced, thus saving compression energy accordingly. Especially when there is an increased demand for cold, the addition of low-boiling components also counteracts the energetically unfavorable tendency to increase the temperature difference during heat transfer.
  • An additional advantage is the feeding of the further fraction in gaseous form according to a further development of the inventive idea.
  • the high proportion of gas bubbles on the evaporation side of the condenser-evaporator results in a strongly turbulent flow and thus an improved heat transfer.
  • the further fraction is formed by a partial stream of the lower-boiling fraction.
  • This usually represents the top fraction of the rectification column, so it has a maximum proportion of low-boiling components.
  • the above-described effect of lowering the vapor pressure on the evaporation side of the condenser-evaporator is therefore greatest. With this procedure, the achievable amount of liquid product can be increased compared to a process without feeding low-boiling components into the evaporation space, without further measures being necessary.
  • the further fraction is formed by a partial flow of the gas mixture to be broken down.
  • the amount of fluid fed into the evaporation chamber is therefore not passed through the rectification column.
  • a correspondingly reduced load on the column can be dimensioned more cost-effectively. Separation work already done to obtain low-boiling product is not lost.
  • the further fraction and the high-boiling fraction can first be mixed and then fed to the evaporation side of the condenser-evaporator.
  • the method according to the invention offers further advantages if the mixture of evaporated heavy-boiling and further fraction downstream of the condenser-evaporator in indirect heat exchange with the gas mixture to be separated warmed up and then relaxed while working.
  • the relaxation can take place, for example, in a relaxation machine, a so-called residual gas turbine.
  • the throughput at the turbine - and thus its cooling capacity - can be increased by feeding the further fraction in accordance with the invention without additionally stressing the rectification column.
  • the particularly high vapor pressure on the evaporation side of the condenser-evaporator can be used to increase the pressure ratio at the residual gas turbine and thus to further improve the refrigeration.
  • a modification of the invention also relates to a process for the separation of a gas mixture, in particular air, in which a product enriched with lower-boiling components, in particular nitrogen, is obtained, a lower-boiling fraction from the upper region of a rectification column in a condenser-evaporator in indirect heat exchange is at least partially condensed with an evaporating heavy-boiling fraction.
  • the evaporated, high-boiling fraction downstream of the condenser-evaporator is heated in indirect heat exchange with the gas mixture to be separated and is then expanded to perform work.
  • This modified form of the invention is also based on the object of making this method more economical, in particular when there is a high need for cooling.
  • This object is achieved in that the heavy-boiling fraction downstream of the condenser-evaporator is fed a further fraction which has a lower proportion of heavy- boiling components than the heavy-boiling fraction.
  • the further fraction can be fed to the heavy-boiling fraction at least partially between the condenser-evaporator and indirect heat exchange with the gas mixture to be broken down and / or at least partially between the indirect heat exchange with the gas mixture to be broken down and relaxation work performed.
  • the further fraction can consist of the lower-boiling fraction from the top of the rectification column or of a gas mixture to be separated (gaseous nitrogen or feed air in the case of use in air separation). Because of the particularly simple implementation, the use of the gas mixture to be broken down is particularly favorable as the further fraction.
  • the heavy-boiling fraction can also be introduced into the lower region of the evaporation side of the condenser / evaporator, as described in detail in DE-A-28 35 355.
  • the inventive method is particularly great advantages in all its variants, if at least a portion of the nitrogen in the condenser-evaporator condensed lower-boiling fraction as a liquid product, in the case of air separation so liquid is obtained.
  • the invention relates to a device according to claims 17 to 21.
  • Air drawn in via line 1 is compressed in compressor 1 to a pressure of 6 to 14, preferably 7 to 10 bar, and treated in a cleaning device 3, for example switchable molecular sieve absorbers.
  • the air freed of impurities flows via line 4 to a heat exchanger 5, in which it is cooled in countercurrent to product flows.
  • the cold air is fed via line 6 into a rectification column 7, the working pressure of which is 6 to 14, preferably 7 to 10 bar.
  • a bottoms fraction 8 enriched with heavy-boiling constituents (here oxygen) is withdrawn from the rectification column 7 in liquid form, subcooled in countercurrent 9, expanded to 5 to 2 bar, preferably 4 to 2 bar in a pressure relief valve 10 and finally introduced into a condenser-evaporator 11.
  • the condenser-evaporator 11 is shown in the drawings as an independent component. Deviating from this, it could also be integrated into the rectification column 7, for example.
  • the fraction evaporated in the condenser-evaporator 11 is drawn off via line 12 and heated in the heat exchangers 9 and 5.
  • the heated residual gas fraction can be used to regenerate the cleaning device 3, as indicated in the drawings by line 17.
  • the invention can also be implemented without this work-relieving relaxation.
  • the evaporation in the condenser-evaporator 11 can also be carried out under a lower pressure.
  • part of the gaseous nitrogen which is not required as a product, is removed via line 24 from the top of the rectification column 7, that is to say a further fraction which has a lower proportion of heavy- boiling components than the heavy-boiling fraction 8 from the bottom of the rectification column 7 , which is fed to the depressed fraction 8 in the expansion valve 10.
  • the mixture is introduced into the evaporation side of the condenser-evaporator 11 and there it enters into indirect heat exchange with another part 19 of the gaseous nitrogen from the rectification column 7.
  • the bottom fraction and the further fraction can be fed to the condenser-evaporator 11 at any point; however, preferably both fractions - together or separately - are fed in at the bottom of the condenser-evaporator 11. Details of such a method and the corresponding device are described in DE-A-28 35 355. This aspect of the method according to the invention brings about not only the enrichment of the evaporating fraction with lower boiling points Components noticeably improved heat transfer at the condenser-evaporator 11.
  • FIGS. 3 and 4 show another possibility of increasing the throughput at the expansion turbine 14 with a correspondingly high cooling requirement.
  • cold, purified air is fed to the vaporized bottom fraction 12 upstream of the turbine 14.
  • This can be implemented via one of the lines 25a or 25b upstream or downstream of the heat exchanger 5; A combined use of the two lines 25a, 25b is also possible.
  • the relaxed bottom fraction is fed into the evaporation space of the condenser-evaporator 11 in a conventional manner, while in the process of FIG. 4 a feed from below is again provided according to DE-A-28 35 355.

Abstract

This process serves for separating a gas mixture (4), in particular air, a product (21; 23), in particular nitrogen, enriched with lower-boiling components, being obtained. A lower-boiling fraction (18, 19) from the upper region of a rectifier column (7) is at least partially condensed in a condenser/evaporator (11) in indirect heat exchange with an evaporating higher-boiling fraction (8). The higher-boiling fraction (8) is, before the indirect heat exchange, supplied with a further fraction (24) which has a lower proportion of higher-boiling components than the higher-boiling fraction (8). <IMAGE>

Description

Die Erfindung betrifft ein Verfahren zur Zerlegung eines Gasgemisches, insbesondere von Luft, bei dem ein an leichtersiedenden Komponenten angereichertes Produkt, insbesondere Stickstoff, gewonnen wird, wobei eine leichtersiedende Fraktion aus dem oberen Bereich einer Rektifiziersäule in einem Kondensator-Verdampfer in indirektem Wärmeaustausch mit einer verdampfenden schwerersiedenden Fraktion mindestens teilweise kondensiert wird, sowie eine Vorrichtung zur Durchführung dieses Verfahrens.The invention relates to a process for the decomposition of a gas mixture, in particular air, in which a product enriched with lower-boiling components, in particular nitrogen, is obtained, a lower-boiling fraction from the upper region of a rectification column in a condenser-evaporator in indirect heat exchange with an evaporating one heavy-boiling fraction is at least partially condensed, and an apparatus for performing this method.

Ein derartiges Verfahren ist aus der EP-A-O 241 817 bekannt. Zur Gewinnung von Stickstoff wird hier kalte gereinigte Luft in einer Rektifiziersäule in eine sauerstoffangereicherte Sumpffraktion und in ein stickstoffreiches Kopfprodukt zerlegt. Die Sumpffraktion wird in einen Kondensator-Verdampfer geleitet und dort gegen kondensierenden Stickstoff verdampft.Such a method is known from EP-A-O 241 817. In order to obtain nitrogen, cold, purified air is broken down in a rectification column into an oxygen-enriched bottom fraction and a nitrogen-rich overhead product. The bottom fraction is passed into a condenser-evaporator and evaporated there against condensing nitrogen.

Der Erfindung liegt die Aufgabe zugrunde, das Verfahren der eingangs genannten Art wirtschaftlich günstiger zu gestalten, insbesondere durch Verbesserung des Wärmeaustauschvorgangs am Kondensator-Verdampfer.The invention has for its object to make the method of the type mentioned economically more economical, in particular by improving the heat exchange process on the condenser-evaporator.

Diese Aufgabe wird dadurch gelöst, daß der schwerersiedenden Fraktion vor dem indirekten Wärmeaustausch eine weitere Fraktion zugeführt wird, die einen geringeren Anteil an schwerersiedenden Komponenten aufweist als die schwerersiedende Fraktion.This object is achieved in that the heavy-boiling fraction is fed a further fraction before the indirect heat exchange, the has a lower proportion of heavy- boiling components than the heavy-boiling fraction.

Eine Vermischung von Fraktionen verschiedener Zusammensetzung bedeutet zunächst offensichtlich einen Nachteil, da dadurch bereits geleistete Trennarbeit wieder verlorengeht. Im Rahmen der Erfindung hat sich jedoch überraschenderweise herausgestellt, daß dieser Nachteil durch eine andere, vorteilhafte Wirkung des Zusatzes leichtersiedender Anteile in die schwerersiedende Fraktion überwogen wird, insbesondere bei besonders hohem Wärmeumsatz am Kondensator-Verdampfer.Mixing fractions of different compositions obviously means a disadvantage at first, since this already results in separation work being lost again. In the present invention, however, has surprisingly been found that this disadvantage is outweighed by another beneficial effect of the addition leichtersied forming units in the higher-boiling fraction, especially at particularly high heat conversion at the condenser-evaporator.

Einerseits kann der Durchsatz auf der Verdampfungsseite des Kondensator-Verdampfers alternativ oder ergänzend zu einem erhöhten Durchsatz der schwerersiedenden Fraktion durch die Zuspeisung einer leichter siedenden Fraktion erhöht werden. Ein besonders hoher Durchsatz an schwerersiedender Fraktion bedeutet nämlich eine zusätzliche Belastung der Rektifiziersäule, da Flüssigkeit am Kopf der Säule kondensiert und durch die Säule wieder über die Böden oder sonstigen Stoffaustauschelemente (z.B. Füllkörper oder geordnete Packungen) nach unten fließt, um anschließend als schwerersiedende Fraktion entnommen werden zu können. Die als zusätzliches Kältemittel eingesetzte weitere Fraktion muß im Gegensatz zu der schwerersiedenden Fraktion nicht zunächst am Kopf der Säule kondensiert und durch praktisch die gesamte Säule geführt werden. Nimmt man gemäß der Erfindung die Vermischung der schwerersiedenden Fraktion mit der weiteren, an schwerersiedenden Komponenten ärmeren Fraktion in Kauf, kann diese Fraktion grundsätzlich an jeder Stelle des Verfahrens entnommen werden, ohne die Säule zu belasten.On the one hand, the throughput on the evaporation side of the condenser-evaporator can be increased as an alternative or in addition to an increased throughput of the heavy-boiling fraction by feeding in a lower-boiling fraction. A particularly high throughput of heavy-boiling fraction means an additional load on the rectification column, since liquid condenses at the top of the column and flows back down through the column through the trays or other mass transfer elements (e.g. packing elements or ordered packings), before being removed as a heavy-boiling fraction to be able to. In contrast to the heavy-boiling fraction, the additional fraction used as additional refrigerant does not first have to be condensed at the top of the column and passed through practically the entire column. If, according to the invention, the mixing of the heavy-boiling fraction with the further fraction poorer in heavy- boiling components is accepted, this fraction can in principle be removed at any point in the process without loading the column.

Zum anderen steigt aufgrund der Erhöhung der leichtersiedenden Anteile der Dampfdruck der siedenden Fraktion auf der Verdampfungsseite des Kondensator-Verdampfers (bei gleichbleibender Verdampfungstemperatur). In Ausnützung dieses Effekts kann der Druck der schwerersiedenden Fraktion und in der Folge der gesamte Verfahrensdruck abgesenkt und damit entsprechend Verdichtungsenergie eingespart werden. Gerade bei erhöhtem Kältebedarf wirkt die Zuspeisung von leichtersiedenden Komponenten außerdem der energetisch ungünstigen Tendenz zur Erhöhung der Temperaturdifferenz beim Wärmeübergang entgegen.Secondly, the boiling fraction increases due to the increase in leichtersied Shares of the vapor pressure on the evaporation side of the condenser-evaporator (at constant evaporation temperature). Taking advantage of this effect, the pressure of the heavy-boiling fraction and subsequently the entire process pressure can be reduced, thus saving compression energy accordingly. Especially when there is an increased demand for cold, the addition of low-boiling components also counteracts the energetically unfavorable tendency to increase the temperature difference during heat transfer.

Einen zusätzlichen Vorteil bringt die Zuspeisung der weiteren Fraktion in Gasform gemäß einer Weiterbildung des erfinderischen Gedankens. Der hohe Anteil an Gasblasen auf der Verdampfungsseite des Kondensator-Verdampfers zieht eine stark turbulente Strömung und damit einen verbesserten Wärmeübergang nach sich.An additional advantage is the feeding of the further fraction in gaseous form according to a further development of the inventive idea. The high proportion of gas bubbles on the evaporation side of the condenser-evaporator results in a strongly turbulent flow and thus an improved heat transfer.

Als weitere Fraktion kann bespielsweise jedes Fluid dienen, das oberhalb der Entnahme der schwerersiedenden Fraktion aus der Rektifiziersäule entnommen wird. Als besonders günstig haben sich jedoch zwei spezielle Varianten erwiesen.Any fluid that is removed from the rectification column above the removal of the heavy-boiling fraction can serve as a further fraction. However, two special variants have proven to be particularly cheap.

In einer ersten bevorzugten Variante wird die weitere Fraktion durch einen Teilstrom der leichtersiedenden Fraktion gebildet. Diese stellt in der Regel die Kopffraktion der Rektifiziersäule dar, hat also einen maximalen Anteil an leichtersiedenden Komponenten. Der oben beschriebene Effekt der Dampfdruckerniedrigung auf der Verdampfungsseite des Kondensator-Verdampfers ist damit am höchsten. Mit dieser Verfahrensweise kann gegenüber einem Verfahren ohne Zuspeisung von leichtersiedenden Komponenten in den Verdampfungsraum die erreichbare Flüssigproduktmenge gesteigert werden, ohne daß weitere Maßnahmen erforderlich sind.In a first preferred variant, the further fraction is formed by a partial stream of the lower-boiling fraction. This usually represents the top fraction of the rectification column, so it has a maximum proportion of low-boiling components. The above-described effect of lowering the vapor pressure on the evaporation side of the condenser-evaporator is therefore greatest. With this procedure, the achievable amount of liquid product can be increased compared to a process without feeding low-boiling components into the evaporation space, without further measures being necessary.

Bei einer zweiten günstigen Variante des erfindungsgemäßen Verfahrens wird die weitere Fraktion durch einen Teilstrom des zu zerlegenden Gasgemisches gebildet. Die in den Verdampfungsraum eingespeiste Fluidmenge wird also nicht durch die Rektifiziersäule geführt. Durch eine entsprechend verringerte Belastung der Säule kann diese kostengünstiger dimensioniert werden. Bereits für die Gewinnung von leichtersiedendem Produkt geleistete Trennarbeit geht nicht verloren.In a second favorable variant of the method according to the invention, the further fraction is formed by a partial flow of the gas mixture to be broken down. The amount of fluid fed into the evaporation chamber is therefore not passed through the rectification column. A correspondingly reduced load on the column can be dimensioned more cost-effectively. Separation work already done to obtain low-boiling product is not lost.

Statt einer Vermischung von schwerersiedender und weiterer Fraktion stromaufwärts des Kondensator-Verdampfers kann es günstig sein, die weitere Fraktion der Verdampfungsseite des Kondensator-Verdampfers zuzuführen. Die Vermischung der beiden Fraktionen findet dann im Verdampfungsraum selbst statt. Gerade bei gasförmiger Zuspeisung der weiteren Fraktion kann die oben beschriebene Verbesserung des Wärmeübergangs besonders effizient ausgenutzt werden.Instead of mixing the high-boiling and further fractions upstream of the condenser-evaporator, it may be expedient to feed the further fraction to the evaporation side of the condenser-evaporator. The two fractions are then mixed in the evaporation chamber itself. The above-described improvement in the heat transfer can be used particularly efficiently, particularly when the further fraction is fed in gaseously.

Dabei hat es sich speziell als vorteilhaft herausgestellt, wenn die weitere Fraktion und/oder die schwerersiedende Fraktion in den unteren Bereich der Verdampfungsseite des Kondensator-Verdampfers eingeleitet werden. Eine entsprechende Vorrichtung und ihre Betriebsweise sind in der DE-A-28 35 355 beschrieben. Dadurch lassen sich ein besonders günstiger Dampfdruck und ein weiter verbesserter Wärmeübergang erreichen.It has been found to be particularly advantageous if the further fraction and / or the heavy-boiling fraction are introduced into the lower region of the evaporation side of the condenser-evaporator. A corresponding device and its mode of operation are described in DE-A-28 35 355. This enables a particularly favorable vapor pressure and a further improved heat transfer to be achieved.

Auf ähnliche Weise können die weitere Fraktion und die schwerersiedende Fraktion zunächst vermischt und anschließend der Verdampfungsseite des Kondensator-Verdampfers zugeführt werden.Similarly, the further fraction and the high-boiling fraction can first be mixed and then fed to the evaporation side of the condenser-evaporator.

Weitere Vorteile bietet das erfindungsgemäße Verfahren, wenn das Gemisch aus verdampfter schwerersiedender und weiterer Fraktion stromabwärts des Kondensator-Verdampfers in indirektem Wärmeaustausch mit zu zerlegendem Gasgemisch angewärmt und anschließend arbeitsleistend entspannt wird. Die Entspannung kann beispielsweise in einer Entspannungsmaschine, einer sogenannten Restgasturbine erfolgen. In diesem Fall kann durch die Zuspeisung der weiteren Fraktion gemäß der Erfindung der Durchsatz an der Turbine - und damit deren Kälteleistung - erhöht werden, ohne die Rektifiziersäule zusätzlich zu belasten. Außerdem kann der besonders hohe Dampfdruck auf der Verdampfungsseite des Kondensator-Verdampfers zur Erhöhung des Druckverhältnisses an der Restgasturbine und damit zur weiterer Verbesserung der Kälteerzeugung ausgenutzt werden.The method according to the invention offers further advantages if the mixture of evaporated heavy-boiling and further fraction downstream of the condenser-evaporator in indirect heat exchange with the gas mixture to be separated warmed up and then relaxed while working. The relaxation can take place, for example, in a relaxation machine, a so-called residual gas turbine. In this case, the throughput at the turbine - and thus its cooling capacity - can be increased by feeding the further fraction in accordance with the invention without additionally stressing the rectification column. In addition, the particularly high vapor pressure on the evaporation side of the condenser-evaporator can be used to increase the pressure ratio at the residual gas turbine and thus to further improve the refrigeration.

Eine Abwandlung der Erfindung betrifft ebenfalls ein Verfahren zur Zerlegung eines Gasgemisches, insbesondere von Luft, bei dem ein an leichtersiedenden Komponenten angereichertes Produkt, insbesondere Stickstoff, gewonnen wird, wobei eine leichtersiedende Fraktion aus dem oberen Bereich einer Rektifiziersäule in einem Kondensator-Verdampfer in indirektem Wärmeaustausch mit einer verdampfenden schwerersiedenden Fraktion mindestens teilweise kondensiert wird. Außerdem wird bei diesem Verfahren die verdampfte schwerersiedende Fraktion stromabwärts des Kondensator-Verdampfers in indirektem Wärmeaustausch mit zu zerlegendem Gasgemisch angewärmt und anschließend arbeitsleistend entspannt.A modification of the invention also relates to a process for the separation of a gas mixture, in particular air, in which a product enriched with lower-boiling components, in particular nitrogen, is obtained, a lower-boiling fraction from the upper region of a rectification column in a condenser-evaporator in indirect heat exchange is at least partially condensed with an evaporating heavy-boiling fraction. In addition, in this process, the evaporated, high-boiling fraction downstream of the condenser-evaporator is heated in indirect heat exchange with the gas mixture to be separated and is then expanded to perform work.

Auch dieser abgewandelten Form der Erfindung liegt die Aufgabe zugrunde, dieses Verfahren wirtschaftlich günstiger zu gestalten, insbesondere bei hohem Kältebedarf.This modified form of the invention is also based on the object of making this method more economical, in particular when there is a high need for cooling.

Diese Aufgabe wird dadurch gelöst, daß der schwerersiedenden Fraktion stromabwärts des Kondensator-Verdampfers eine weitere Fraktion zugeführt wird, die einen geringeren Anteil an schwerersiedenden Komponenten aufweist als die schwerersiedende Fraktion.This object is achieved in that the heavy-boiling fraction downstream of the condenser-evaporator is fed a further fraction which has a lower proportion of heavy- boiling components than the heavy-boiling fraction.

Ähnlich wie bei der erstgenannten Variante der Erfindung wird als der schwerersiedenden Fraktion eine weitere Fraktion anderer Zusammensetzung zugeführt, ohne daß diese durch die Säule geführt werden müßte. Hierdurch läßt sich der Durchsatz bei der arbeitsleistenden Entspannung erhöhen, ohne daß dadurch die Säule belastet würde. Auch hier kann der damit erreichte Vorteil den Nachteil des Verlustes von Trennarbeit bei der Vermischung aufwiegen.Similar to the first variant of the invention, a further fraction of a different composition is fed in as the heavy-boiling fraction without it having to be passed through the column. As a result, the throughput during work-relieving relaxation can be increased without the column being burdened thereby. Here, too, the advantage thus achieved can outweigh the disadvantage of the loss of separation work during mixing.

Die weitere Fraktion kann der schwerersiedenden Fraktion mindestens teilweise zwischen Kondensator-Verdampfer und indirektem Wärmeaustausch mit zu zerlegendem Gasgemisch und/oder mindestens teilweise zwischen indirektem Wärmeaustausch mit zu zerlegendem Gasgemisch und arbeitsleistender Entspannung zugeführt werden.The further fraction can be fed to the heavy-boiling fraction at least partially between the condenser-evaporator and indirect heat exchange with the gas mixture to be broken down and / or at least partially between the indirect heat exchange with the gas mixture to be broken down and relaxation work performed.

Wiederum kann die weitere Fraktion aus der leichtersiedenden Fraktion vom Kopf der Rektifiziersäule oder aus zu zerlegendem Gasgemisch (gasförmiger Stickstoff beziehungsweise Einsatzluft im Falle der Anwendung bei der Luftzerlegung) bestehen. Wegen der besonders einfachen Realisierung ist hier die Verwendung des zu zerlegenden Gasgemisches als die weitere Fraktion besonders günstig.Again, the further fraction can consist of the lower-boiling fraction from the top of the rectification column or of a gas mixture to be separated (gaseous nitrogen or feed air in the case of use in air separation). Because of the particularly simple implementation, the use of the gas mixture to be broken down is particularly favorable as the further fraction.

Analog zu den weiter oben erläuterten Varianten der Erfindung kann auch bei der Abwandlung des Verfahren die schwerersiedende Fraktion in den unteren Bereich der Verdampfungsseite des Kondensator/Verdampfers eingeleitet werden, wie es in der DE-A-28 35 355 im Detail beschrieben ist.Analogous to the variants of the invention explained further above, when the method is modified, the heavy-boiling fraction can also be introduced into the lower region of the evaporation side of the condenser / evaporator, as described in detail in DE-A-28 35 355.

Das erfindungsgemäße Verfahren zeigt in allen Varianten besonders große Vorteile, wenn mindestens ein Teil der im Kondensator-Verdampfer kondensierten leichtersiedenden Fraktion als Flüssigprodukt, im Falle der Luftzerlegung also flüssiger Stickstoff, gewonnen wird.The inventive method is particularly great advantages in all its variants, if at least a portion of the nitrogen in the condenser-evaporator condensed lower-boiling fraction as a liquid product, in the case of air separation so liquid is obtained.

Die Erfindung betrifft über das bisher beschriebene Verfahren hinaus eine Vorrichtung gemäß den Patentansprüchen 17 bis 21.In addition to the method described so far, the invention relates to a device according to claims 17 to 21.

Im folgenden werden die Erfindung sowie weitere Einzelheiten der Erfindung anhand von Ausführungsbeispielen näher erläutert, die in den Zeichnungen schematisch dargestellt sind. Die gezeigten Verfahren dienen zur Gewinnung von Stickstoff aus Luft; die Erfindung ist jedoch ohne weiteres auf die Zerlegung von anderen Zweistoffgemischen übertragbar.The invention and further details of the invention are explained in more detail below with reference to exemplary embodiments which are shown schematically in the drawings. The processes shown are used to extract nitrogen from air; however, the invention is readily transferable to the decomposition of other two-substance mixtures.

Es zeigen im einzelnen:

Figur 1:
ein Luftzerlegungsverfahren gemäß der Erfindung mit Zuspeisung von Stickstoff in die Verdampfungsseite des Kondensator-Verdampfers
Figur 2:
ein ähnliches Verfahren mit Zuspeisung von Luft
Figur 3:
ein stärker abgewandeltes Verfahren mit einer Restgasturbine und der Zuspeisung von Luft stromaufwärts der Turbine
Figur 4:
eine Abwandlung des Verfahrens von Figur 3 mit Einspeisung von unten in den Kondensator-Verdampfer
The individual shows:
Figure 1:
an air separation process according to the invention with feeding nitrogen into the evaporation side of the condenser-evaporator
Figure 2:
a similar process with the addition of air
Figure 3:
a more modified process with a residual gas turbine and the supply of air upstream of the turbine
Figure 4:
a modification of the method of Figure 3 with feeding from below into the condenser-evaporator

Zunächst werden die den Ausführungsbeispielen gemeinsamen Verfahrensmerkmale beschrieben. Über Leitung 1 angesaugte Luft wird in Verdichter 1 auf einen Druck von 6 bis 14, vorzugsweise 7 bis 10 bar verdichtet und in einer Reinigungsvorrichtung 3, beispielsweise umschaltbaren Molsiebadsorbern, behandelt. Die von Verunreinigungen befreite Luft strömt über Leitung 4 zu einem Wärmetauscher 5, in dem sie im Gegenstrom zu Produktströmen abgekühlt wird. Über Leitung 6 wird die kalte Luft in eine Rektifiziersäule 7 eingespeist, deren Arbeitsdruck bei 6 bis 14, vorzugsweise 7 bis 10 bar liegt.The method features common to the exemplary embodiments are first described. Air drawn in via line 1 is compressed in compressor 1 to a pressure of 6 to 14, preferably 7 to 10 bar, and treated in a cleaning device 3, for example switchable molecular sieve absorbers. The air freed of impurities flows via line 4 to a heat exchanger 5, in which it is cooled in countercurrent to product flows. The cold air is fed via line 6 into a rectification column 7, the working pressure of which is 6 to 14, preferably 7 to 10 bar.

Aus der Rektifiziersäule 7 wird eine an schwerersiedenden Bestandteilen (hier Sauerstoff) angereichterte Sumpffraktion 8 flüssig entnommen, in Gegenströmer 9 unterkühlt, in einem Entspannungsventil 10 auf 5 bis 2 bar, vorzugsweise 4 bis 2 bar entspannt und schließlich in einen Kondensator-Verdampfer 11 eingeleitet. Der Kondensator-Verdampfer 11 ist in den Zeichnungen als eigenständiges Bauelement dargestellt. Hiervon abweichend könnte er beispielsweise auch in die Rektifiziersäule 7 integriert sein.A bottoms fraction 8 enriched with heavy-boiling constituents (here oxygen) is withdrawn from the rectification column 7 in liquid form, subcooled in countercurrent 9, expanded to 5 to 2 bar, preferably 4 to 2 bar in a pressure relief valve 10 and finally introduced into a condenser-evaporator 11. The condenser-evaporator 11 is shown in the drawings as an independent component. Deviating from this, it could also be integrated into the rectification column 7, for example.

Die im Kondensator-Verdampfer 11 verdampfte Fraktion wird über Leitung 12 abgezogen, und in den Wärmetauschern 9 und 5 angewärmt. Die auf eine mittlere Temperatur von 140 bis 115, vorzugsweise 130 bis 115 K angewärmte Restgasfraktion 13 wird in einer Entspannungsturbine 14 auf einen Druck von 1,5 bis 1,1 , vorzugsweise 1,3 bis 1,2 bar arbeitsleistend entspannt, über Leitung 15 zum Wärmetauscher 5 geführt und verläßt diesen unter etwa Umgebungstemperatur über Leitung 16. Die angewärmte Restgasfraktion kann zur Regenerierung der Reinigungsvorrichtung 3 verwendet werden, wie in den Zeichnungen durch Leitung 17 angedeutet ist. Die Erfindung kann bei den Verfahren der Figuren 1 und 2 auch ohne diese arbeitsleistende Entspannung realisiert werden. In diesem Fall kann die Verdampfung im Kondensator-Verdampfer 11 auch unter einem niedrigeren Druck durchgeführt werden.The fraction evaporated in the condenser-evaporator 11 is drawn off via line 12 and heated in the heat exchangers 9 and 5. The residual gas fraction 13, which has been heated to an average temperature of 140 to 115, preferably 130 to 115 K, is expanded in a pressure-reducing turbine 14 to a pressure of 1.5 to 1.1, preferably 1.3 to 1.2 bar, via line 15 led to the heat exchanger 5 and leaves it at approximately ambient temperature via line 16. The heated residual gas fraction can be used to regenerate the cleaning device 3, as indicated in the drawings by line 17. In the methods of FIGS. 1 and 2, the invention can also be implemented without this work-relieving relaxation. In this case, the evaporation in the condenser-evaporator 11 can also be carried out under a lower pressure.

Am Kopf der Rektifiziersäule 7 wird Stickstoff 18 als leichtersiedende Fraktion gasförmig entnommen, über Leitung 19 zum Kondensator-Verdampfer 11 geführt und dort in indirektem Wärmeaustausch mit der verdampfenden Sumpffraktion mindestens teilweise, vorzugsweise vollständig kondensiert. Das Kondensat wird teilweise über Leitung 20 als Rücklauf auf die Rektifiziersäule 7 aufgegeben und teilweise als Flüssigprodukt (Leitung 21) entnommen.At the top of rectification column 7, nitrogen is removed in gaseous form as the low-boiling fraction 18, via line 19 to the condenser-evaporator 11 and guided there in indirect heat exchange with the vaporizing bottoms fraction is at least partially, preferably fully condensed. The condensate is partly fed via line 20 as a return to rectification column 7 and partly removed as a liquid product (line 21).

Ein anderer Teil des gasförmig aus der Rektifiziersäule 7 herausgeführten Stickstoffs 18 wird über Leitung 22 zum Wärmetauscher 5 geleitet, dort auf etwa Umgebungstemperatur angewärmt und als gasförmiges, an leichtersiedenden Komponenten angereichertes Produkt abgezogen (23).Another part of the gas conducted out of the rectification column 7 nitrogen 18 is passed via line 22 to the heat exchanger 5, there warmed to approximately ambient temperature and withdrawn as gaseous, enriched in lower-boiling component product (23).

Beim Verfahren der Figur 1 wird über Leitung 24 ein Teil des gasförmigen, nicht als Produkt benötigten Stickstoffs vom Kopf der Rektifiziersäule 7, also eine weitere Fraktion, die einen geringeren Anteil an schwerersiedenden Komponenten aufweist als die schwerersiedende Fraktion 8 aus dem Sumpf der Rektifiziersäule 7, der in Entspannungsventil 10 entspannten Sumpffraktion 8 zugespeist. Das Gemisch wird in die Verdampfungsseite des Kondensator-Verdampfers 11 eingeführt und tritt dort in indirekten Wärmeaustausch mit einem anderen Teil 19 des gasförmigen Stickstoffs aus der Rektifiziersäule 7. Statt einer Einführung des Gemischs in den Kondensator-Verdampfer 11 ist auch eine getrennte Einführung von entspannter Sumpffraktion und weiterer Fraktion 24 in den Verdampfungsraum des Kondensator-Verdampfers 11 möglich.In the method of FIG. 1, part of the gaseous nitrogen, which is not required as a product, is removed via line 24 from the top of the rectification column 7, that is to say a further fraction which has a lower proportion of heavy- boiling components than the heavy-boiling fraction 8 from the bottom of the rectification column 7 , which is fed to the depressed fraction 8 in the expansion valve 10. The mixture is introduced into the evaporation side of the condenser-evaporator 11 and there it enters into indirect heat exchange with another part 19 of the gaseous nitrogen from the rectification column 7. Instead of introducing the mixture into the condenser-evaporator 11, there is also a separate introduction of the relaxed bottom fraction and another fraction 24 in the evaporation space of the condenser-evaporator 11 possible.

Im Prinzip können die Sumpffraktion und die weitere Fraktion an jeder Stelle dem Kondensator-Verdampfer 11 zugeführt werden; bevorzugt werden jedoch beide Fraktionen - gemeinsam oder getrennt - an der Unterseite des Kondensator-Verdampfers 11 eingespeist. Einzelheiten eines derartigen Verfahrens und der entsprechenden Vorrichtung sind in der DE-A-28 35 355 beschrieben. Dieser Aspekt des erfindungsgemäßen Verfahrens bewirkt neben der Anreicherung der verdampfenden Fraktion an leichter siedenden Komponenten einen spürbar verbesserten Wärmeübergang am Kondensator-Verdampfer 11.In principle, the bottom fraction and the further fraction can be fed to the condenser-evaporator 11 at any point; however, preferably both fractions - together or separately - are fed in at the bottom of the condenser-evaporator 11. Details of such a method and the corresponding device are described in DE-A-28 35 355. This aspect of the method according to the invention brings about not only the enrichment of the evaporating fraction with lower boiling points Components noticeably improved heat transfer at the condenser-evaporator 11.

Im Unterschied zu dem soeben beschriebenen Verfahren wird in der Variante von Figur 2 nicht ein Teil des Kopfprodukts, sondern ein Teil der gereinigten kalten Luft, also des zu zerlegenden Gasgemisches, über eine Leitung 24' der entspannten Sumpffraktion vor dem Verdampfen im Kondensator-Verdampfer 11 zugespeist.In contrast to the method just described, in the variant of FIG. 2 not part of the top product, but part of the cleaned cold air, that is to say the gas mixture to be broken down, is passed via a line 24 ′ of the relaxed bottom fraction before evaporation in the condenser-evaporator 11 fed.

Die Figuren 3 und 4 zeigen eine andere Möglichkeit, den Durchsatz an der Entspannungsturbine 14 bei entsprechend hohem Kältebedarf zu erhöhen. Hier wird kalte gereinigte Luft der verdampften Sumpffraktion 12 stromaufwärts der Turbine 14 zugespeist. Dies kann über eine der Leitungen 25a oder 25b stromaufwärts oder stromabwärts des Wärmetauschers 5 realisiert werden; auch eine kombinierte Benutzung der beiden Leitungen 25a, 25b ist möglich.FIGS. 3 and 4 show another possibility of increasing the throughput at the expansion turbine 14 with a correspondingly high cooling requirement. Here, cold, purified air is fed to the vaporized bottom fraction 12 upstream of the turbine 14. This can be implemented via one of the lines 25a or 25b upstream or downstream of the heat exchanger 5; A combined use of the two lines 25a, 25b is also possible.

In Figur 3 wird dabei abweichend von den bisherien Ausführungsbeispielen die entspannte Sumpffraktion auf konventionelle Weise in den Verdampfungsraum des Kondensator-Verdampfers 11 eingespeist, während beim Verfahren von Figur 4 wiederum eine Zuspeisung von unten gemäß DE-A-28 35 355 vorgesehen ist.In FIG. 3, in a departure from the previous exemplary embodiments, the relaxed bottom fraction is fed into the evaporation space of the condenser-evaporator 11 in a conventional manner, while in the process of FIG. 4 a feed from below is again provided according to DE-A-28 35 355.

Claims (19)

  1. Process for separating a gas mixture (4), in particular air, in which a product (21; 23) enriched in lower-boiling components, in particular nitrogen, is recovered, a lower-boiling fraction (18, 19) from the upper region of a rectifying column (7) being condensed at least in part in a condenser-evaporator (11) in indirect heat exchange with an evaporating higher-boiling fraction (8), characterized in that, upstream of the indirect heat exchange, a further fraction (24; 24') is fed to the higher-boiling fraction (8), which further fraction has a lower content of higher-boiling components than the higher-boiling fraction (8).
  2. Process according to Claim 1, characterized in that the further fraction (24; 24') is fed to the higher-boiling fraction in the gaseous state.
  3. Process according to Claim 1 or 2, characterized in that the further fraction is formed by a partial stream (24) of the lower-boiling fraction (18).
  4. Process according to Claim 1 or 2, characterized in that the further fraction is formed by a partial stream (24') of the gas mixture to be separated.
  5. Process according to one of Claims 1 to 4, characterized in that the further fraction (24; 24') is fed to the evaporation side of the condenser-evaporator (11).
  6. Process according to one of Claims 1 to 4, characterized in that the further fraction (24; 24') and the higher-boiling fraction (8) are mixed and are then fed to the evaporation side of the condenser-evaporator 11).
  7. Process according to one of Claims 1 to 6, characterized in that the mixture (12) of evaporated higher-boiling fraction and further fraction is heated downstream of the condenser-evaporator (11) in indirect heat exchange (5) with the gas mixture (4) to be separated and is then expanded (14) in a manner performing work.
  8. Process for separating a gas mixture (4), in particular air, in which a product (21; 23), enriched in lower-boiling components, in particular nitrogen, is recovered, a lower-boiling fraction (18) from the upper region of a rectifying column (7) being condensed at least in part in a condenser-evaporator (11) in indirect heat exchange with an evaporating higher-boiling fraction (8) and the evaporated higher-boiling fraction.(12) being heated downstream of the condenser-evaporator (11) in indirect heat exchange (5) with gas mixture (4) to be separated and then expanded (14) in a manner performing work, characterized in that a further fraction (25a, 25b) is fed to the higher-boiling fraction (12) downstream of the condenser-evaporator, which further fraction (25a, 25b) has a lower content of higher-boiling components than the higher-boiling fraction.
  9. Process according to Claim 8, characterized in that the further fraction (25a) is fed to the higher-boiling fraction (12) at least in part between condenser-evaporator (11) and indirect heat exchange (5) with the gas mixture (4) to be separated.
  10. Process according to Claim 8 or 9, characterized in that the further fraction (25b) is fed to the higher-boiling fraction (12) at least in part between indirect heat exchange (5) with gas mixture (4) to be separated and work-performing expansion (14).
  11. Process according to one of Claims 8 to 10, characterized in that the further fraction is formed by a partial stream of the lower-boiling fraction.
  12. Process according to one of Claims 8 to 10, characterized in that the further fraction (25a, 25b) is formed by a partial stream of the gas mixture (4) to be separated.
  13. Process according to one of Claims 8 to 12, characterized in that the higher-boiling fraction (8) is introduced into the lower region of the evaporation side of the condenser-evaporator (11) .
  14. Process according to one of Claims 1 to 13, characterized in that at least some of the lower-boiling fraction condensed in the condenser-evaporator (11) is obtained as liquid product (21).
  15. Apparatus for carrying out the process according to one of Claims 1 to 3 having a feed line (6) for gas mixture to be separated, which feed line leads to a rectifying column (7); a bottom fraction line (8) which leads from the lower region of the rectifying column (7) to the evaporation side of a condenser-evaporator (11); a residual gas line (12) to remove gas from the evaporation side of the condenser-evaporator (11); a top gas line (19) which conducts gas from the upper region of the rectifying column (7) to the liquefaction side of the condenser-evaporator (11); and a product line (18, 22) which is connected to the upper region of the rectifying column (7), characterized by a further line (24) which is connected to the rectifying column (7) at a point above the bottom fraction line (8) connection and is connected to the evaporation side of the condenser-evaporator (11).
  16. Apparatus for carrying out the process according to Claim 4 having a feed line (6) for gas mixture to be separated, which feed line leads to a rectifying column (7); a bottom fraction line (8) which leads from the lower region of the rectifying column (7) to the evaporation side of a condenser-evaporator (11); a residual gas line (12) to remove gas from the evaporation side of the condenser-evaporator (11); a top gas line (19) which conducts gas from the upper region of the rectifying column (7) to the liquefaction side of the condenser-evaporator (11); and a product line (18, 22) which is connected to the upper region of the rectifying column (7), characterized by a further line (24') which leads from the feed line (6) to the evaporation side of the condenser-evaporator (11) .
  17. Apparatus according to Claim 15 or 16, characterized in that the residual gas line (12) leads to an expansion machine (14).
  18. Apparatus for carrying out the process according to one of Claims 8 to 13 having a feed line (6) for gas mixture to be separated, which feed line leads to a rectifying column (7); a bottom fraction line (8) which leads from the lower region of the rectifying column (7) to the evaporation side of a condenser-evaporator (11); a residual gas line (12) which is connected to the evaporation side of the condenser-evaporator (11) and to an expansion machine (14); a top gas line (19) which conducts gas from the upper region of the rectifying column (7) to the liquefaction side of the condenser-evaporator (11); and a product line (18, 22) which is connected to the upper region of the rectifying column (7), characterized by a further line (25a, 25b) which leads from the feed line (6) to the residual gas line (12).
  19. Apparatus according to one of Claims 15 to 18, characterized by a liquid product line (21) to remove liquid from the liquefaction side of the condenser-evaporator (11).
EP93103226A 1992-03-05 1993-03-01 Process and apparatus for separating a gas mixture Expired - Lifetime EP0559117B1 (en)

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DE4415861A1 (en) * 1994-05-05 1995-11-16 Hans Dr Ing Foerster Process for the separation of vaporous constituents from air loaded with high proportions of low-boiling components
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