EP0775881B1 - Process and apparatus for recovering oxygen and nitrogen at superatmospheric pressure - Google Patents

Process and apparatus for recovering oxygen and nitrogen at superatmospheric pressure Download PDF

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Publication number
EP0775881B1
EP0775881B1 EP96118281A EP96118281A EP0775881B1 EP 0775881 B1 EP0775881 B1 EP 0775881B1 EP 96118281 A EP96118281 A EP 96118281A EP 96118281 A EP96118281 A EP 96118281A EP 0775881 B1 EP0775881 B1 EP 0775881B1
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Prior art keywords
pressure column
low
pressure
column
vapour
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EP96118281A
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German (de)
French (fr)
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EP0775881A3 (en
EP0775881A2 (en
Inventor
Dietrich Dipl.-Ing. Rottmann
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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
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04896—Details of columns, e.g. internals, inlet/outlet devices
    • F25J3/04915—Combinations of different material exchange elements, e.g. within different columns
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04084—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04103—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression using solely hydrostatic liquid head
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/04193—Division of the main heat exchange line in consecutive sections having different functions
    • F25J3/04206—Division of the main heat exchange line in consecutive sections having different functions including a so-called "auxiliary vaporiser" for vaporising and producing a gaseous product
    • F25J3/04212—Division of the main heat exchange line in consecutive sections having different functions including a so-called "auxiliary vaporiser" for vaporising and producing a gaseous product and simultaneously condensing vapor from a column serving as reflux within the or another column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04321—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04363—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04406—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
    • F25J3/04424—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 without thermally coupled high and low pressure columns, i.e. a so-called split columns
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04642—Recovering noble gases from air
    • F25J3/04648—Recovering noble gases from air argon
    • F25J3/04654—Producing crude argon in a crude argon column
    • F25J3/04666—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system
    • F25J3/04672—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser
    • F25J3/04678—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser cooled by oxygen enriched liquid from high pressure column bottoms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04872—Vertical layout of cold equipments within in the cold box, e.g. columns, heat exchangers etc.
    • F25J3/04878—Side by side arrangement of multiple vessels in a main column system, wherein the vessels are normally mounted one upon the other or forming different sections of the same 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
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/50—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being oxygen

Definitions

  • the invention relates to a process for the production of oxygen and nitrogen superatmospheric pressure due to low temperature separation of air in one Rectification column system, which has a pressure column and a low pressure column, with steps (a) to (g) listed in claim 1.
  • the invention is therefore based on the object, a method and a specify appropriate device of the type mentioned, with which at the same time, oxygen and nitrogen are obtained under superatmospheric pressure can be and which work particularly economically, especially through a high yield of oxygen.
  • This object is achieved in that the pressure of the liquid from the lower Area of the low pressure column upstream of the indirect heat exchange with condensing steam from the top of the pressure column is increased and that part of the steam obtained in indirect heat exchange, which in the low pressure column is returned before being introduced into the low pressure column is relaxed.
  • the pressures of the pressure column and the low pressure column decoupled that is, the pressure column can operate under particularly high pressure be (for example 8 bar, 10 bar or higher), whereas the pressure in the Low pressure column only at just above atmospheric pressure, for example at 1.2 to 2.0 bar, preferably 1.5 to 1.6 bar.
  • the pressure column pressure can to the desired nitrogen product pressure - so that the nitrogen product compressor can either be made smaller or can be omitted -, and the low pressure column can still operate with an optimal separation effect become.
  • the pressure of the liquid from the lower area of the low pressure column can be raised by any of the known methods, for example by a pump and / or by a hydrostatic potential.
  • the final pressure must are sufficient so that the liquid in the indirect heat exchange with the Pressure column pressure condensing vapor evaporates from the pressure column.
  • Indirect heat exchange serves on the one hand to cool the head of the pressure column - es becomes liquid return for the pressure column and if necessary for the Low-pressure column - on the other hand - creates a detour through an oxygen cycle with pressure increase in the liquid and gaseous expansion - for generation of rising steam for the low pressure column.
  • the steam obtained in indirect heat exchange is preferred warmed against feed air. Usually only a part of the warmed gas relaxed in the low pressure column. The rest can then continue on Ambient temperature warmed and as a gaseous oxygen pressure product be dissipated.
  • the two liquids passed from the pressure column to the low pressure column usually consist of sump liquid from the pressure column (first Liquid fraction) or from liquid from the top of the pressure column or from an intermediate point, the 10 to 30, preferably 20 theoretical floors below of the head of the pressure column (second liquid fraction).
  • the relaxation of the indirect heat exchange through evaporation of the Liquid obtained from the lower part of the low pressure column is vapor preferably performed work, for example in a Expansion turbine. A lot of process cold can thus be obtained. It is favorable if a magnetic or gas-bearing turbine is used as the expansion turbine Turbine is used.
  • At least part of the relaxation of the indirect Heat generated steam can generate energy for compression a process stream can be used, for example for compressing a nitrogenous fraction from the low pressure column to regenerate one Molecular sieve necessary pressure.
  • the devices for relaxation or compression are preferably mechanically coupled, for example by a common wave.
  • the steam obtained in indirect heat exchange can be upstream of the Relaxation can be heated in the low pressure column. This warming takes place preferably in a main heat exchanger, which is also used to cool the Operating air serves.
  • the part of the steam to be relaxed is generally led out of the main heat exchanger at a temperature between the Temperatures at the cold and warm end of the main heat exchanger.
  • an argon-containing fraction can be transferred from the low pressure column into a Raw argon column can be introduced. Details of such argon production are for example in EP-B-377117, EP-A-628777 or EP-A-669509 described.
  • the invention also relates to a device for producing oxygen and Nitrogen under superatmospheric pressure due to the low temperature decomposition of air according to claims 7 to 11.
  • Compressed and cleaned from water and carbon dioxide feed air 1 is in one Main heat exchanger 2 cooled to about dew point and via line 3 under one Pressure of 10 bar fed into a pressure column 4.
  • vaporous nitrogen which still contains about 1 ppm of impurities
  • Line 10 removed and to a part 11 in a head capacitor trained condenser-evaporator 12 condenses; the rest will be on line 14 led to the main heat exchanger 2, warmed there to about ambient temperature and discharged at 15 as a gaseous pressure product. That in the condenser evaporator 12 obtained condensate 13 serves as a return for the pressure column 4; to the others, it can be partially discharged as a liquid product 16.
  • Oxygen-enriched bottom liquid 5 is the first liquid fraction from the Throttled pressure column in a low pressure column 7 (6).
  • a second liquid fraction 8 20 theoretical plates below the head of the pressure column are subtracted and above the first liquid fraction, preferably at the top, into the low pressure column relaxed 9. (Alternatively or additionally, the one drawn off via line 16 could also be used Liquid is applied to the low pressure column 7.)
  • the bottom liquid of the low pressure column 7 (third liquid fraction 17) is by a Pump 18 brought to a pressure of about 5 bar, subcooled in a countercurrent and introduced into the evaporation space of the condenser-evaporator 12. A part the pumped liquid can be withdrawn as product 21 if required.
  • the one in Condenser-evaporator 12 won steam 22 is in the main heat exchanger 2 introduced and in part at the warm end 23 as a gaseous Print product won.
  • the rest is at an intermediate point from the Main heat exchanger 2 led out (24), in a turbine 25 to work about low pressure column pressure relaxed and through the counterflow 19 in the Low pressure column 7 fed back.
  • Nitrogen-containing residual gas 28 is drawn off from the top of the low-pressure column 7, first warmed against the two liquid fractions from the pressure column (29) and finally continued to the main heat exchanger 2.
  • the heated residual gas 30 can be discarded, for example, or as a regeneration gas for a molecular sieve system be used for air purification.
  • the two exemplary embodiments can additionally have a crude argon column 34 be equipped; for the case of FIG. 1, this is detailed in FIG. 3.
  • An argon vapor fraction 35 is emitted from a location of relatively high argon content led in the low pressure column 7 to the crude argon column 34 and there into a - for example, via liquid line 36 - crude argon fraction and into one Residual fraction 37 disassembled.
  • the head cooling 39 of the raw argon column 34 is carried out by Evaporation of a portion 38 of the bottom liquid 5 from the pressure column causes.
  • the steam 40 thereby generated is fed into the low-pressure column 7.
  • the mass transfer elements in the pressure column formed by still bottoms, those in the low pressure column and optionally in the crude argon column by orderly packing. Basically, however, at Invention in all columns conventional still bottoms, packing (disordered Pack) and / or ordered pack. Combinations too Different types of elements are possible in one column. Because of the small Ordered packs, especially in the low pressure column, become pressure loss prefers.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Gewinnung von Sauerstoff und Stickstoff unter überatmosphärischem Druck durch Tieftemperaturzerlegung von Luft in einem Rektifiziersäulensystem, das eine Drucksäule und eine Niederdrucksäule aufweist, mit den im Patentanspruch 1 aufgeführten Schritten (a) bis (g).The invention relates to a process for the production of oxygen and nitrogen superatmospheric pressure due to low temperature separation of air in one Rectification column system, which has a pressure column and a low pressure column, with steps (a) to (g) listed in claim 1.

Ein Verfahren mit diesen Schritten ist aus der US-A-4224045 bekannt. Druck- und Niederdrucksäule sind durch einen im Sumpf der Niederdrucksäule angeordneten Kondensator-Verdampfer thermisch gekoppelt. Das Druckstickstoffprodukt wird am Kopf der Drucksäule abgezogen. Will man auch das Sauerstoffprodukt, das in der Niederdrucksäule anfällt, unter Druck gewinnen, kann man entweder die gesamte Doppelsäule oder wenigstens die Niederdrucksäule unter einem entsprechend erhöhten Druck betreiben oder das Sauerstoffprodukt flüssig auf Druck bringen und anschließend gegen Einsatzluft verdampfen (Innenverdichtung). Kälte könnte entweder durch die Entspannung von stickstoffreichem Restgas aus der Niederdrucksäule (nur im ersten Fall möglich) oder durch die Entspannung eines Teils der Einsatzluft in die Niederdrucksäule (wie in US-A-4224045 gezeigt) erzeugt werden. Sowohl die Direkteinspeisung von Luft als auch der Betrieb der Niederdrucksäule unter erhöhtem Druck verschlechtern jedoch die Rektifikation in der Niederdrucksäule und verringern damit Ausbeute und/oder Reinheit des Sauerstoffprodukts.A method with these steps is known from US-A-4224045. Printing and Low pressure columns are arranged in the sump of the low pressure column Condenser-evaporator thermally coupled. The pressure nitrogen product is on Head of the pressure column removed. Do you also want the oxygen product that is in the Low pressure column occurs, gain under pressure, you can either the entire Double column or at least the low pressure column under one accordingly operate at elevated pressure or pressurize the oxygen product liquid and then evaporate against feed air (internal compression). Cold could either by releasing nitrogen-rich residual gas from the Low pressure column (only possible in the first case) or by relaxing a part the feed air into the low pressure column (as shown in US-A-4224045) become. Both the direct supply of air and the operation of the Low pressure column under increased pressure, however, deteriorate the rectification in the Low pressure column and thus reduce the yield and / or purity of the Oxygen product.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren und eine entsprechende Vorrichtung der eingangs genannten Art anzugeben, mit denen gleichzeitig Sauerstoff und Stickstoff unter überatmosphärischem Druck gewonnen werden können und die besonders wirtschaftlich arbeiten, insbesondere durch eine hohe Ausbeute an Sauerstoff.The invention is therefore based on the object, a method and a specify appropriate device of the type mentioned, with which at the same time, oxygen and nitrogen are obtained under superatmospheric pressure can be and which work particularly economically, especially through a high yield of oxygen.

Diese Aufgabe wird dadurch gelöst, daß der Druck der Flüssigkeit aus dem unteren Bereich der Niederdrucksäule stromaufwärts des indirekten Wärmeaustauschs mit kondensierendem Dampf aus dem oberen Bereich der Drucksäule erhöht wird und derjenige Teil des bei dem indirekten Wärmeaustausch gewonnenen Dampfs, der in die Niederdrucksäule zurückgeführt wird, vor der Einleitung in die Niederdrucksäule entspannt wird. This object is achieved in that the pressure of the liquid from the lower Area of the low pressure column upstream of the indirect heat exchange with condensing steam from the top of the pressure column is increased and that part of the steam obtained in indirect heat exchange, which in the low pressure column is returned before being introduced into the low pressure column is relaxed.

Gemäß der Erfindung werden damit die Drücke von Drucksäule und Niederdrucksäule entkoppelt, das heißt die Drucksäule kann unter besonders hohem Druck betrieben werden (beispielsweise 8 bar, 10 bar oder höher), wogegen der Druck in der Niederdrucksäule nur bei knapp über Atmosphärendruck, beispielsweise bei 1,2 bis 2,0 bar, vorzugsweise 1,5 bis 1,6 bar liegt. Somit kann sich der Drucksäulendruck nach dem gewünschten Stickstoff-Produktdruck richten - so daß der Stickstoff-Produktverdichter entweder kleiner ausgeführt oder werden oder ganz entfallen kann -, und die Niederdrucksäule kann dennoch mit optimaler Trennwirkung gefahren werden. Der Druck der Flüssigkeit aus dem unteren Bereich der Niederdrucksäule kann durch jede der bekannten Methoden angehoben werden, beispielsweise durch eine Pumpe und/oder durch ein hydrostatisches Potential. Der Enddruck muß ausreichen, damit die Flüssigkeit bei dem indirekten Wärmeaustausch mit dem bei Drucksäulendruck kondensierenden Dampf aus der Drucksäule verdampft.According to the invention, the pressures of the pressure column and the low pressure column decoupled, that is, the pressure column can operate under particularly high pressure be (for example 8 bar, 10 bar or higher), whereas the pressure in the Low pressure column only at just above atmospheric pressure, for example at 1.2 to 2.0 bar, preferably 1.5 to 1.6 bar. Thus, the pressure column pressure can to the desired nitrogen product pressure - so that the nitrogen product compressor can either be made smaller or can be omitted -, and the low pressure column can still operate with an optimal separation effect become. The pressure of the liquid from the lower area of the low pressure column can be raised by any of the known methods, for example by a pump and / or by a hydrostatic potential. The final pressure must are sufficient so that the liquid in the indirect heat exchange with the Pressure column pressure condensing vapor evaporates from the pressure column.

Der indirekte Wärmeaustausch dient einerseits zur Kopfkühlung der Drucksäule - es wird flüssiger Rücklauf für die Drucksäule und gegebenenfalls für die Niederdrucksäule erzeugt - andererseits - über den Umweg eines Sauerstoffkreislaufs mit Druckerhöhung in der Flüssigkeit und gasförmiger Entspannung - zur Erzeugung von aufsteigendem Dampf für die Niederdrucksäule.Indirect heat exchange serves on the one hand to cool the head of the pressure column - es becomes liquid return for the pressure column and if necessary for the Low-pressure column - on the other hand - creates a detour through an oxygen cycle with pressure increase in the liquid and gaseous expansion - for generation of rising steam for the low pressure column.

Der bei dem indirekten Wärmeaustausch gewonnene Dampf wird vorzugsweise gegen Einsatzluft angewärmt. In der Regel wird nur ein Teil des angewärmten Gases in die Niederdrucksäule entspannt. Der Rest kann dann weiter auf Umgebungstemperatur erwärmt und als gasförmiges Sauerstoff-Druckprodukt abgeführt werden.The steam obtained in indirect heat exchange is preferred warmed against feed air. Usually only a part of the warmed gas relaxed in the low pressure column. The rest can then continue on Ambient temperature warmed and as a gaseous oxygen pressure product be dissipated.

Es ist günstig, wenn bei der Erfindung in der Niederdrucksäule wenigstens teilweise, vorzugsweise ausschließlich geordnete Packungen als Stoffaustauschelemente eingesetzt werden. Durch deren besonders geringen Druckverlust kann der Druck im unteren Bereich der Niederdrucksäule weiter erniedrigt werden.It is advantageous if, in the invention, at least partially in the low pressure column, preferably only ordered packs as mass transfer elements be used. Due to their particularly low pressure drop, the pressure in the lower area of the low pressure column can be further reduced.

Die beiden Flüssigkeiten, die von der Drucksäule in die Niederdrucksäule geleitet werden, bestehen in der Regel aus Sumpfflüssigkeit der Drucksäule (erste Flüssigfraktion) beziehungsweise aus Flüssigkeit vom Kopf der Drucksäule oder von einer Zwischenstelle, die 10 bis 30, vorzugsweise 20 theoretische Böden unterhalb des Kopfes der Drucksäule liegt (zweite Flüssigfraktion). The two liquids passed from the pressure column to the low pressure column usually consist of sump liquid from the pressure column (first Liquid fraction) or from liquid from the top of the pressure column or from an intermediate point, the 10 to 30, preferably 20 theoretical floors below of the head of the pressure column (second liquid fraction).

Die Entspannung des bei dem indirekten Wärmeaustausch durch Verdampfung der Flüssigkeit aus dem unteren Bereich der Niederdrucksäule gewonnenen Dampfs wird vorzugsweise arbeitsleistend durchgeführt, beispielsweise in einer Entspannungsturbine. Damit kann besonders viel Verfahrenskälte gewonnen werden. Es ist günstig, wenn als Entspannungsturbine eine magnet- oder gasgelagerte Turbine eingesetzt wird.The relaxation of the indirect heat exchange through evaporation of the Liquid obtained from the lower part of the low pressure column is vapor preferably performed work, for example in a Expansion turbine. A lot of process cold can thus be obtained. It is favorable if a magnetic or gas-bearing turbine is used as the expansion turbine Turbine is used.

Mindestens ein Teil der bei der Entspannung des bei dem indirekten Wärmeaustausch gewonnenen Dampfs erzeugten Energie kann zur Verdichtung eines Prozeßstroms verwendet werden, beispielsweise zur Kompression einer stickstoffhaltigen Fraktion aus der Niederdrucksäule auf den zur Regenerierung einer Molekularsiebanlage notwendigen Druck. Die Vorrichtungen zur Entspannung beziehungsweise Verdichtung sind vorzugsweise mechanisch gekoppelt, beispielsweise durch eine gemeinsame Welle.At least part of the relaxation of the indirect Heat generated steam can generate energy for compression a process stream can be used, for example for compressing a nitrogenous fraction from the low pressure column to regenerate one Molecular sieve necessary pressure. The devices for relaxation or compression are preferably mechanically coupled, for example by a common wave.

Der bei dem indirekten Wärmeaustausch gewonnene Dampf kann stromaufwärts der Entspannung in die Niederdrucksäule erwärmt werden. Diese Erwärmung findet vorzugsweise in einem Hauptwärmetauscher statt, der auch zur Abkühlung der Einsatzluft dient. Der zu entspannende Teil des Dampfes wird dabei im allgemeinen bei einer Temperatur aus dem Hauptwärmetauscher herausgeführt, die zwischen den Temperaturen am kalten und warmen Ende des Hauptwärmetauschers liegt.The steam obtained in indirect heat exchange can be upstream of the Relaxation can be heated in the low pressure column. This warming takes place preferably in a main heat exchanger, which is also used to cool the Operating air serves. The part of the steam to be relaxed is generally led out of the main heat exchanger at a temperature between the Temperatures at the cold and warm end of the main heat exchanger.

Ein Teil des bei dem indirekten Wärmeaustausch gewonnenen Dampfs - beispielsweise derjenige, der nicht der Entspannung zugeführt wird - wird vorzugsweise als Sauerstoffdruckprodukt gewonnen. Damit dient eine einzige Vorrichtung, in der Regel eine Sauerstoffpumpe - zur Erzeugung des erhöhten Drucks sowohl für die Produktmenge als auch für die zwecks Kälteerzeugung im Kreislauf geführte Menge.Part of the steam obtained from indirect heat exchange - for example, the one who is not brought to relaxation preferably obtained as an oxygen pressure product. So one serves Device, usually an oxygen pump - to generate the increased pressure both for the amount of product and for the purpose of cooling in the circuit guided crowd.

Wegen der günstigen Verhältnisse durch den niedrigen Druck in der Niederdrucksäule ist das erfindungsgemäße Verfahren auch zur Gewinnung von Argon geeignet. Zu diesem Zweck kann eine argonhaltige Fraktion aus der Niederdrucksäule in eine Rohargonsäule eingeleitet werden. Einzelheiten einer derartigen Argongewinnung sind beispielsweise in der EP-B-377117, der EP-A-628777 oder der EP-A-669509 beschrieben. Because of the favorable conditions due to the low pressure in the low pressure column the inventive method is also suitable for the production of argon. To For this purpose, an argon-containing fraction can be transferred from the low pressure column into a Raw argon column can be introduced. Details of such argon production are for example in EP-B-377117, EP-A-628777 or EP-A-669509 described.

Die Erfindung betrifft außerdem eine Vorrichtung zur Gewinnung von Sauerstoff und Stickstoff unter überatmosphärischem Druck durch Tieftemperaturzerlegung von Luft gemäß den Patentansprüchen 7 bis 11.The invention also relates to a device for producing oxygen and Nitrogen under superatmospheric pressure due to the low temperature decomposition of air according to claims 7 to 11.

Die Erfindung sowie weitere Einzelheiten der Erfindung werden im folgenden anhand von in den Zeichnungen dargestellten Ausführungsbeispielen näher erläutert. Hierbei zeigen:

Figur 1
ein erstes, besonders bevorzugtes Ausführungsbeispiel des Verfahrens und der Vorrichtung gemäß der Erfindung,
Figur 2
ein weiteres Ausführungsbeispiel mit Rückverdichtung des stickstoffreichen Restgases aus der Niederdrucksäule und
Figur 3
ein drittes Ausführungsbeispiel mit Argongewinnung.
The invention and further details of the invention are explained in more detail below with reference to exemplary embodiments shown in the drawings. Here show:
Figure 1
a first, particularly preferred embodiment of the method and the device according to the invention,
Figure 2
a further embodiment with recompression of the nitrogen-rich residual gas from the low pressure column and
Figure 3
a third embodiment with argon production.

Verdichtete und von Wasser und Kohlendioxid gereinigte Einsatzluft 1 wird in einem Hauptwärmetauscher 2 auf etwa Taupunkt abgekühlt und über Leitung 3 unter einem Druck von 10 bar in eine Drucksäule 4 eingespeist. Am Kopf der Drucksäule wird dampfförmiger Stickstoff, der noch etwa 1 ppm Verunreinigungen enthält, über Leitung 10 entnommen und zu einem Teil 11 in einem als Kopfkondensator ausgebildeten Kondensator-Verdampfer 12 kondensiert; der Rest wird über Leitung 14 zum Hauptwärmetauscher 2 geführt, dort auf etwa Umgebungstemperatur erwärmt und bei 15 als gasförmiges Druckprodukt abgeführt. Das im Kondensator-Verdampfer 12 gewonnene Kondensat 13 dient zum einen als Rücklauf für die Drucksäule 4; zum anderen kann es teilweise als Flüssigprodukt 16 abgeführt werden.Compressed and cleaned from water and carbon dioxide feed air 1 is in one Main heat exchanger 2 cooled to about dew point and via line 3 under one Pressure of 10 bar fed into a pressure column 4. At the head of the pressure column vaporous nitrogen, which still contains about 1 ppm of impurities Line 10 removed and to a part 11 in a head capacitor trained condenser-evaporator 12 condenses; the rest will be on line 14 led to the main heat exchanger 2, warmed there to about ambient temperature and discharged at 15 as a gaseous pressure product. That in the condenser evaporator 12 obtained condensate 13 serves as a return for the pressure column 4; to the others, it can be partially discharged as a liquid product 16.

Sauerstoffangereicherte Sumpfflüssigkeit 5 wird als erste Flüssigfraktion aus der Drucksäule in eine Niederdrucksäule 7 eingedrosselt (6). Eine zweite Flüssigfraktion 8 wird 20 theoretische Böden unterhalb des Kopfes der Drucksäule abgezogen und oberhalb der ersten Flüssigfraktion, vorzugsweise am Kopf, in die Niederdrucksäule entspannt 9. (Alternativ oder zusätzlich könnte auch die über Leitung 16 abgezogene Flüssigkeit auf die Niederdrucksäule 7 aufgegeben werden.)Oxygen-enriched bottom liquid 5 is the first liquid fraction from the Throttled pressure column in a low pressure column 7 (6). A second liquid fraction 8 20 theoretical plates below the head of the pressure column are subtracted and above the first liquid fraction, preferably at the top, into the low pressure column relaxed 9. (Alternatively or additionally, the one drawn off via line 16 could also be used Liquid is applied to the low pressure column 7.)

Die Sumpfflüssigkeit der Niederdrucksäule 7 (dritte Flüssigfraktion 17) wird durch eine Pumpe 18 auf einen Druck von ca. 5 bar gebracht, in einem Gegenströmer unterkühlt und in den Verdampfungsraum des Kondensator-Verdampfers 12 eingeführt. Ein Teil der gepumpten Flüssigkeit kann bei Bedarf als Produkt 21 abgezogen werden. Der im Kondensator-Verdampfer 12 gewonnene Dampf 22 wird in den Hauptwärmetauscher 2 eingeführt und zu einem Teil an dessen warmem Ende 23 als gasförmiges Druckprodukt gewonnen. Der Rest wird an einer Zwischenstelle aus dem Hauptwärmetauscher 2 herausgeführt (24), in einer Turbine 25 arbeitsleistend auf etwa Niederdrucksäulendruck entspannt und durch den Gegenströmer 19 in die Niederdrucksäule 7 zurückgespeist.The bottom liquid of the low pressure column 7 (third liquid fraction 17) is by a Pump 18 brought to a pressure of about 5 bar, subcooled in a countercurrent and introduced into the evaporation space of the condenser-evaporator 12. A part the pumped liquid can be withdrawn as product 21 if required. The one in Condenser-evaporator 12 won steam 22 is in the main heat exchanger 2 introduced and in part at the warm end 23 as a gaseous Print product won. The rest is at an intermediate point from the Main heat exchanger 2 led out (24), in a turbine 25 to work about low pressure column pressure relaxed and through the counterflow 19 in the Low pressure column 7 fed back.

Stickstoffhaltiges Restgas 28 wird vom Kopf der Niederdrucksäule 7 abgezogen, zunächst gegen die beiden Flüssigfraktionen aus der Drucksäule angewärmt (29) und schließlich weiter zum Hauptwärmetauscher 2 geführt. Das angewärmte Restgas 30 kann beispielsweise verworfen oder als Regeneriergas für eine Molekularsiebanlage zur Luftreinigung verwendet werden.Nitrogen-containing residual gas 28 is drawn off from the top of the low-pressure column 7, first warmed against the two liquid fractions from the pressure column (29) and finally continued to the main heat exchanger 2. The heated residual gas 30 can be discarded, for example, or as a regeneration gas for a molecular sieve system be used for air purification.

Im letzteren Fall ist es günstig, wenn derjenige Teil 31 des Restgases 30, der für die Regenerierung benötigt wird, in einem Verdichter 32 auf den Regenerierdruck gebracht wird, wie es in Figur 2 gezeigt ist. (Figur 2 stimmt bis auf dieses Detail mit Figur 1 überein.) Dieser kann - beispielsweise über eine gemeinsame Welle 33 - von der Turbine 25 angetrieben werden. Mit Hilfe dieser Maßnahme ist es möglich, den Druck in der Niederdrucksäule weiter abzusenken, beispielsweise auf ca. 1,1 bar. Dies ermöglicht wiederum eine Verringerung des Turbinenaustrittsdrucks und damit eine Erhöhung des Kälteleistungspotentials.In the latter case, it is advantageous if that part 31 of the residual gas 30 that for the Regeneration is required in a compressor 32 to the regeneration pressure is brought, as shown in Figure 2. (Figure 2 agrees except for this detail 1.) This can - for example via a common shaft 33 - from the turbine 25 are driven. With the help of this measure it is possible to Lower the pressure in the low pressure column further, for example to approx. 1.1 bar. This in turn enables a reduction in the turbine outlet pressure and thus an increase in the cooling capacity potential.

Die beiden Ausführungsbeispiele können zusätzlich mit einer Rohargonsäule 34 ausgestattet werden; für den Fall der Figur 1 ist dies in Figur 3 im Detail ausgeführt. Eine argonhaltige Dampffraktion 35 wird von einer Stelle relativ hohen Argongehalts in der Niederdrucksäule 7 zur Rohargonsäule 34 geführt und dort in eine - beispielsweise über Leitung 36 flüssig abgeführte - Rohargonfraktion und in eine Restfraktion 37 zerlegt. Die Kopfkühlung 39 der Rohargonsäule 34 wird durch Verdampfung eines Teils 38 der Sumpfflüssigkeit 5 aus der Drucksäule bewirkt. Der dabei entstandene Dampf 40 wird in die Niederdrucksäule 7 eingespeist.The two exemplary embodiments can additionally have a crude argon column 34 be equipped; for the case of FIG. 1, this is detailed in FIG. 3. An argon vapor fraction 35 is emitted from a location of relatively high argon content led in the low pressure column 7 to the crude argon column 34 and there into a - for example, via liquid line 36 - crude argon fraction and into one Residual fraction 37 disassembled. The head cooling 39 of the raw argon column 34 is carried out by Evaporation of a portion 38 of the bottom liquid 5 from the pressure column causes. The steam 40 thereby generated is fed into the low-pressure column 7.

In den Ausführungsbeispielen werden die Stoffaustauschelemente in der Drucksäule durch Destillierböden gebildet, diejenigen in der Niederdrucksäule und gegebenenfalls in der Rohargonsäule durch geordnete Packung. Grundsätzlich können jedoch bei der Erfindung in allen Säulen konventionelle Destillierböden, Füllkörper (ungeordnete Packung) und/oder geordnete Packung eingesetzt werden. Auch Kombinationen verschiedenartiger Elemente in einer Säule sind möglich. Wegen des geringen Druckverlusts werden geordnete Packungen insbesondere in der Niederdrucksäule bevorzugt.In the exemplary embodiments, the mass transfer elements in the pressure column formed by still bottoms, those in the low pressure column and optionally in the crude argon column by orderly packing. Basically, however, at Invention in all columns conventional still bottoms, packing (disordered Pack) and / or ordered pack. Combinations too Different types of elements are possible in one column. Because of the small Ordered packs, especially in the low pressure column, become pressure loss prefers.

Claims (11)

  1. Process for producing oxygen and nitrogen at superatmospheric pressure by low-temperature fractionation of air in a rectification column system which has a pressure column (4) and a low-pressure column (7) and has the following steps:
    (a) introduction of compressed and purified feed air (1,3) into the pressure column (4),
    (b) introduction (6) of at least a part of a first liquid fraction (5) from the lower region of the pressure column (4) into the low-pressure column (7),
    (c) introduction (9) of a second liquid fraction (8) from the upper or central region of the pressure column (4) into the low-pressure column (7),
    (d) vaporization of a third liquid fraction (17) from the lower region of the low-pressure column (7) in indirect heat exchange (12) with condensing vapour (11) from the upper region of the pressure column (4),
    (e) introduction of at least a part of the vapour (22, 24, 26, 27) produced in the indirect heat exchange into the low-pressure column (7),
    (f) introduction of at least a part of the condensate (13) produced in the indirect heat exchange into the pressure column (4),
    (g) take-off of a pressurized nitrogen fraction (10, 14, 15) as product from the upper region of the pressure column (4),
    characterized in that
    (h) the pressure of the third liquid fraction (17) from the lower region of the low-pressure column (7) is increased upstream of the indirect heat exchange (12) with condensing vapour (11) from the upper region of the pressure column (4) and
    (i) that part (24) of the vapour produced in the indirect heat exchange which is recycled into the low-pressure column (7) is expanded (25) upstream of the introduction (27) into the low-pressure column (7).
  2. Process according to Claim 1, characterized in that the vapour produced in the indirect heat exchange is work-expanded (25) in accordance with step (i).
  3. Process according to Claim 2, characterized in that at least a part of the energy generated in the expansion (25) of the vapour produced in the indirect heat exchange is used for the compression (32) of a process stream (31).
  4. Process according to one of Claims 1 to 3, characterized in that the vapour (22) produced in the indirect heat exchange is heated (2) upstream of the expansion (25) in accordance with step (i).
  5. Process according to one of Claims 1 to 4, characterized in that a part (23) of the vapour (22) produced in the indirect heat exchange (12) is produced as pressurized oxygen product.
  6. Process according to one of Claims 1 to 5, characterized in that an argon-containing fraction (35) from the low-pressure column (7) is introduced into a crude-argon column (34).
  7. Apparatus for producing oxygen and nitrogen at superatmospheric pressure by low-temperature fractionation of air in a rectification column system which has a pressure column (4) and a low-pressure column (7) and has
    (a) a feed airline (1, 3) for the introduction of compressed and purified feed air into the pressure column (4),
    (b) a first liquid fraction line (5) which connects the lower region of the pressure column (4) to the low-pressure column (7),
    (c) a second liquid fraction line (8) which connects the upper or central region of the pressure column (4) to the low-pressure column (7),
    (d) a condenser/evaporator (12) whose vaporization space is connected via a third liquid fraction line (17) to the lower region of the low-pressure column (7) and the condensation space of which is connected (via 10, 11) to the upper region of the pressure column (4),
    (e) a vapour line (22, 24, 26, 27) between the vaporization space of the condenser/evaporator (12) and the low-pressure column (7),
    (f) a fourth liquid fraction line (13) between the condensation space of the condenser/evaporator (12) and the pressure column (4) and having
    (g) a pressurized nitrogen product line (10, 14, 15) which is connected to the upper region of the pressure column (4),
    characterized by
    (h) means (18) for increasing the pressure in the third liquid fraction line (17) and
    (i) means (25) for decreasing the pressure in the vapour line (22, 24, 26, 27) between condenser/evaporator (12) and low-pressure column (7).
  8. Apparatus according to Claim 7, characterized in that the means for reducing the pressure have an expansion machine (25).
  9. Apparatus according to Claim 7 or 8, characterized by an oxygen product line (23), which is connected to the vapour line (22).
  10. Apparatus according to one of Claims 7 to 9, characterized by means (33) for transmitting mechanical energy from the expansion machine (25) to a compressor (32) for compressing a process stream (31).
  11. Apparatus according to one of Claims 7 to 10, characterized by a crude-argon column (34) which is connected (35, 37) to the low-pressure column.
EP96118281A 1995-11-25 1996-11-14 Process and apparatus for recovering oxygen and nitrogen at superatmospheric pressure Expired - Lifetime EP0775881B1 (en)

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EP0775881A3 (en) 1997-08-20
US5749246A (en) 1998-05-12
TW332856B (en) 1998-06-01
KR970028406A (en) 1997-06-24
DE19543953C1 (en) 1996-12-19
JPH09170874A (en) 1997-06-30
DE59605238D1 (en) 2000-06-21
EP0775881A2 (en) 1997-05-28
MX9605785A (en) 1998-05-31
CA2191161A1 (en) 1997-05-26
ZA969797B (en) 1997-06-10
BR9605678A (en) 1998-08-18

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