EP1300640A1 - Process and device for producing ultra-high purity Nitrogen by cryogenic separation of air - Google Patents

Process and device for producing ultra-high purity Nitrogen by cryogenic separation of air Download PDF

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Publication number
EP1300640A1
EP1300640A1 EP02022022A EP02022022A EP1300640A1 EP 1300640 A1 EP1300640 A1 EP 1300640A1 EP 02022022 A EP02022022 A EP 02022022A EP 02022022 A EP02022022 A EP 02022022A EP 1300640 A1 EP1300640 A1 EP 1300640A1
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EP
European Patent Office
Prior art keywords
pressure column
low
nitrogen
refrigerant
low pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02022022A
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German (de)
French (fr)
Inventor
Stefan Lochner
Ralph Spöri
Michael Lauter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Linde GmbH
Original Assignee
Linde GmbH
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Filing date
Publication date
Priority claimed from DE2001148820 external-priority patent/DE10148820A1/en
Priority claimed from DE10148818A external-priority patent/DE10148818A1/en
Application filed by Linde GmbH filed Critical Linde GmbH
Publication of EP1300640A1 publication Critical patent/EP1300640A1/en
Withdrawn legal-status Critical Current

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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
    • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
    • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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
    • F25J3/04254—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using the cold stored in external cryogenic fluids
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04309—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
    • 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
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04854—Safety aspects of operation
    • F25J3/0486—Safety aspects of operation of vaporisers for oxygen enriched liquids, e.g. purging of liquids
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/50—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column
    • F25J2200/54—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column in the low pressure column of a double pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/90—Details relating to column internals, e.g. structured packing, gas or liquid distribution
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/42—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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/42—Nitrogen or special cases, e.g. multiple or low purity N2
    • F25J2215/44—Ultra high purity nitrogen, i.e. generally less than 1 ppb impurities
    • 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
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/42—Separating low boiling, i.e. more volatile components from nitrogen, e.g. He, H2, Ne
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S62/00—Refrigeration
    • Y10S62/912—External refrigeration system

Definitions

  • the invention relates to a method for the production of nitrogen by Cryogenic decomposition of air in a rectification system containing a pressure column and having a low pressure column, wherein in the process feed air into the pressure column introduced, an oxygen-containing liquid fraction removed from the pressure column and is fed into the low-pressure column, gaseous nitrogen above a Mass transfer section, the at least one theoretical or has practical floor, deducted from the low pressure column and in one Top condenser by indirect heat exchange with a refrigerant at least is partially condensed and high purity nitrogen below the Removed mass transfer section from the low pressure column and as Nitrogen product is recovered.
  • the invention is based on the object, a method of the type mentioned and to provide a corresponding device that economically particularly favorable are.
  • the method is a refrigeration feed system in which a refrigerant fluid flows and at least a portion of the refrigerant fluid from the Refrigeration supply system above the mass transfer section in the low pressure column is initiated.
  • a refrigerant fluid flows and at least a portion of the refrigerant fluid from the Refrigeration supply system above the mass transfer section in the low pressure column is initiated.
  • an introduction is within the scope of the invention the refrigerant fluid from the refrigeration supply system in the upper region of the pressure column possible.
  • the refrigerant fluid can be formed in the invention by a readily available medium be introduced into the low pressure column and thus the mass transfer involved in the low-pressure column without affecting the purity of the highly pure Nitrogen product is affected and without the operating pressure of the Low pressure column can be tailored to the needs of the refrigeration system got to.
  • a suitable cryogenic fluid is nitrogen, which is still Contains volatile contaminants.
  • a residual fraction for example from Evaporation space of the top condenser, deducted, working to about Atmospheric pressure is released and removed from the process. This is the minimum operating pressure the top condenser and thus that of the low pressure column alone through the cold supply system. This disadvantage is in the invention avoided without reducing product purity.
  • the refrigerant fluid is in the invention preferably at the top of the low pressure column fed.
  • the refrigerant fluid from the pressure column removed, in the refrigeration supply system work performing relaxed and in the Low pressure column initiated.
  • the Refrigerant fluid is preferably upstream of its work-performing expansion in Indirect heat exchange against cooled process streams warmed up.
  • the mass transfer section is separated by one or more rectification plates (see above) mentioned floors) - this is the indication in "practical" number of shelves - or by a short packing section ("theoretical" number of plates).
  • the number of For example, barrier floors or theoretical floors amounts to 1 to 10, preferably 2 to 3.
  • the refrigerant fluid is usually lighter than nitrogen volatile components. Thanks to the Infeed above the described mass transfer section get this but not in the further withdrawn nitrogen product.
  • cooling fluid from the upper region of the pressure column is removed. It is characterized by a nitrogen-rich gas fraction from the Pressure column formed, in particular by the head gas.
  • the cooling fluid is passed through a deep-cold Liquid formed outside the rectification system.
  • the cryogenic liquid can be, for example, by liquid nitrogen formed from another air separation plant; Altematively can any other mixture of air components can be used.
  • the external one Liquid can either be introduced via a pipeline or from a Storage tanks are removed. The feed takes place at the point that the composition of the external fluid corresponds. This can be the top one Be the area of the pressure or low pressure column.
  • the cryogenic liquid may partially or completely enter the low pressure column are introduced, preferably at the head.
  • the deep cold liquid at least partially in the upper part of the pressure column be introduced.
  • refrigerant for the top condenser from the bottom of the Low pressure column removed, and the entire oxygenated product of Pressure column is fed into the low pressure column.
  • oxygenated here every fraction is understood, whose oxygen content is greater than that of the air is.
  • the nitrogen product can be withdrawn in gaseous form from the low pressure column. Alternatively, it is taken from the low-pressure column in liquid and in indirect Heat exchange with work-performing expanded refrigerant fluid evaporates. Also one Combination of these two process steps is possible.
  • the invention also relates to a device according to claims 10 to 12th
  • Compressed and purified air 1 is cooled in the embodiment of Figure 1 in a main heat exchanger 2 and a pressure column 4 under a pressure of 9 to 13 bar supplied (3).
  • the rectification system also has a low-pressure column 5 which is operated at a pressure of 2 to 5 bar and is in heat-exchanging communication with the pressure column via a common condenser-evaporator (main condenser) 6.
  • Part 8 of the nitrogen withdrawn at the top of the pressure column is liquefied in the main condenser 6 and partly fed via lines 9 and 10 as reflux to the pressure column.
  • Another stream 14 of the liquid 9 from the main condenser 6 is subcooled (15) and fed to a first part 20 as reflux of the low pressure column 5 at the top.
  • To a second part 21 of the supercooled nitrogen is withdrawn as a liquid product PLIN.
  • Bottom liquid 11 of the pressure column is throttled after supercooling 15 as an oxygen-containing liquid fraction in the low-pressure column 5 (12).
  • the bottom liquid 13 of the low-pressure column 5 is also undercooled (15) and relaxed (16) and then into the evaporation space of the top condenser 17th introduced the low pressure column 5. Condensed in the liquefaction space gaseous nitrogen 18 from the top of the low-pressure column 5; the condensate 19 is in the low pressure column returned and used there as an additional return. Out the lower portion of the evaporation space of the top condenser 17 is over Line 22 continuously or intermittently a flushing fluid (PURGE) deducted.
  • PURGE flushing fluid
  • the generated in the top condenser 17 steam 23 is in the heat exchanger 15 and the second warmed to about ambient temperature and discarded via line 24 and / or as a regeneration gas for a cleaning device, not shown (for example Molecular sieve station) used. Via a line 35 is not condensed gas, which in particular contains more volatile components, deducted. It will blown off (36) and / or admixed with the steam 23 (37).
  • a mass transfer section 25 which in the example is formed by three practical floors (barrier floors).
  • gaseous nitrogen via line 26 as a highly pure product taken and in the heat exchanger 15 and 2 to about ambient temperature warmed up.
  • the warm nitrogen product 27 can be used immediately as a final product (PGAN) be used or it is - as shown in the drawing - first in one Nitrogen compressor 28 with aftercooler 29 further compressed and finally over Deducted line 30.
  • cryogenic liquid from outside the rectification system into one of the columns of the Rectification is initiated
  • Liquid Assist a cryogenic liquid from outside the rectification system into one of the columns of the Rectification is initiated
  • the cryogenic Liquid may not necessarily have been generated outside the rectification system; rather, liquid can also be used for emergency operation (for example, liquid nitrogen) used during normal operation of the plant and in one Storage tank is stored.
  • the embodiment of Figure 1 can be modified so that in the Low pressure column, a gaseous and / or liquid oxygen product is generated.
  • a gaseous and / or liquid oxygen product is generated.
  • the feed 16 of bottoms of the Low pressure column in this evaporation space is omitted in whole or in part. From the Sump area of the low-pressure column 5, the oxygen product is gaseous and / or withdrawn liquid.
  • Compressed and cleaned air 1 is cooled in the embodiment of Figure 2 in a main heat exchanger 2 and a pressure column 4 under a pressure of 9 to 10 bar supplied (3).
  • the rectification system also has a low-pressure column 5 which is operated at a pressure of 2 to 3 bar and is in heat-exchanging communication with the pressure column via a common condenser-evaporator (main condenser) 6.
  • the withdrawn at the top of the pressure column nitrogen 8 is liquefied in the main condenser 6 and partially abandoned via lines 9 and 10 as reflux to the pressure column.
  • Another part 14 of the liquid 9 from the main condenser 6 is subcooled (15) and fed to a first part 20 as reflux of the low pressure column 5 at the top.
  • To a second part 21 of the supercooled nitrogen is withdrawn as a liquid product PLIN.
  • Bottom liquid 11 of the pressure column is throttled after supercooling 15 as an oxygen-containing liquid fraction in the low-pressure column 5 (12).
  • the bottom liquid 13 of the low-pressure column 5 is also undercooled (15) and relaxed (16) and then into the evaporation space of the top condenser 17th introduced the low pressure column 5. Condensed in the liquefaction space gaseous nitrogen 18 from the top of the low-pressure column 5; the condensate 19 is in the low pressure column returned and used there as an additional return. Out the lower portion of the evaporation space of the top condenser 17 is over Line 22 continuously or intermittently a flushing fluid (PURGE) deducted.
  • PURGE flushing fluid
  • the generated in the top condenser 17 steam 23 is in the heat exchanger 15 and the second warmed to about ambient temperature and discarded via line 24 and / or as a regeneration gas for a cleaning device, not shown (for example Molecular sieve station) used. Via a line 35 is not condensed gas, which in particular contains more volatile components, deducted. It will blown off (36) and / or admixed with the steam 23 (37).
  • a mass transfer section 25 which in the example is formed by three practical floors (barrier floors).
  • gaseous nitrogen via line 26 as a highly pure product taken and in the heat exchanger 15 and 2 to about ambient temperature warmed up.
  • the warm nitrogen product 27 can be used immediately as a final product (PGAN) be used or it is - as shown in the drawing - first in one Nitrogen compressor 28 with aftercooler 29 further compressed and finally over Deducted line 30.
  • liquid nitrogen from the storage tank 39 as a refrigerant fluid in the Pressure column are fed (not in the drawing ) Shown.
  • the embodiment of Figure 2 can be modified so that in the Low pressure column, a gaseous and / or liquid oxygen product is generated.
  • a gaseous and / or liquid oxygen product is generated.
  • the feed 16 of bottoms of the Low pressure column in this evaporation space is omitted in whole or in part. From the Sump area of the low-pressure column 5, the oxygen product is gaseous and / or withdrawn liquid.

Abstract

Recovery of pure nitrogen (I) by low temperature rectification of air, by feeding air into pressure column (A), feeding liquid fraction containing oxygen into low pressure column (B), discharging nitrogen gas above substance exchange section (B1), with (partial) condensation, and taking (I) below (B1). (Part of) cold fluid is passed from a flowing supply system into (B) above (B1) or into upper zone of (A). <??>Recovery of highly pure nitrogen (I) by low temperature separation of air in a rectifier system involves feeding air (1, 3) into a pressure column (4); taking a liquid fraction (11) containing oxygen and feeding this into a low pressure column (5); discharging gaseous nitrogen (18) above a substance exchange section (25) with at least one theoretical or practical plate; (partly) condensing this in a head condenser (17) by indirect heat exchange with a refrigerant (13); and taking (I) (26, 27, 30) from the low pressure column (5) below the substance exchange section (25). The novelty is that the process uses a refrigerant supply system with flowing cold fluid (II) (31, 32, 34; 38) and at least part of (II) is passed from the supply system into the low pressure column (5) above the substance exchange system (25) or into the upper zone of the pressure column (4). <??>An Independent claim is also included for the apparatus used.

Description

Die Erfindung betrifft ein Verfahren zur Gewinnung von Stickstoff durch Tieftemperaturzerlegung von Luft in einem Rektifiziersystem, das eine Drucksäule und eine Niederdrucksäule aufweist, wobei bei dem Verfahren Einsatzluft in die Drucksäule eingeleitet, eine sauerstoffhaltige flüssige Fraktion aus der Drucksäule entnommen und in die Niederdrucksäule eingespeist wird, gasförmiger Stickstoff oberhalb eines Stoffaustauschabschnitts, der mindestens einen theoretischen beziehungsweise praktischen Boden aufweist, aus der Niederdrucksäule abgezogen und in einem Kopfkondensator durch indirekten Wärmeaustausch mit einem Kältemittel mindestens teilweise kondensiert wird und hoch reiner Stickstoff unterhalb des Stoffaustauschabschnitts aus der Niederdrucksäule entnommen und als Stickstoffprodukt gewonnen wird.The invention relates to a method for the production of nitrogen by Cryogenic decomposition of air in a rectification system containing a pressure column and having a low pressure column, wherein in the process feed air into the pressure column introduced, an oxygen-containing liquid fraction removed from the pressure column and is fed into the low-pressure column, gaseous nitrogen above a Mass transfer section, the at least one theoretical or has practical floor, deducted from the low pressure column and in one Top condenser by indirect heat exchange with a refrigerant at least is partially condensed and high purity nitrogen below the Removed mass transfer section from the low pressure column and as Nitrogen product is recovered.

Derartige Verfahren und entsprechende Vorrichtungen sind aus EP 948730 B1 und EP 955509 A1 bekannt. Hier kann in der Niederdrucksäule Stickstoff unter erhöhtem Druck gewonnen werden. Baut man Sperrböden ("Stoffaustauschabschnitt, der mindestens einen theoretischen beziehungsweise praktischen Boden aufweist," in den oberen Bereich der Niederdrucksäule ein, kann das Stickstoffprodukt besonders hohe Reinheit aufweisen, insbesondere einen sehr geringen Gehalt an leichtflüchtigen Verunreinigungen.Such methods and corresponding devices are known from EP 948730 B1 and EP 955509 A1. Here, in the low-pressure column, nitrogen can be used under elevated pressure Pressure to be gained. Build Floors ("Mass transfer section, the has at least one theoretical or practical ground, "in the the upper region of the low pressure column, the nitrogen product can be particularly high Have purity, in particular a very low content of volatile Impurities.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art und eine entsprechende Vorrichtung anzugeben, die wirtschaftlich besonders günstig sind.The invention is based on the object, a method of the type mentioned and to provide a corresponding device that economically particularly favorable are.

Diese Aufgabe wird dadurch gelöst, dass das Verfahren ein Kältezuführungssystem aufweist, in dem ein Kältefluid strömt und mindestens ein Teil des Kältefluids aus dem Kältezuführungssystem oberhalb des Stoffaustauschabschnitts in die Niederdrucksäule eingeleitet wird. Alternativ oder zusätzlich ist im Rahmen der Erfindung eine Einführung des Kältefluids aus dem Kältezuführungssystem in den oberen Bereich der Drucksäule möglich. This object is achieved in that the method is a refrigeration feed system in which a refrigerant fluid flows and at least a portion of the refrigerant fluid from the Refrigeration supply system above the mass transfer section in the low pressure column is initiated. Alternatively or additionally, an introduction is within the scope of the invention the refrigerant fluid from the refrigeration supply system in the upper region of the pressure column possible.

Das Kältefluid kann bei der Erfindung durch ein leicht erhältliches Medium gebildet werden, das in die Niederdrucksäule eingeleitet wird und damit an dem Stoffaustausch in der Niederdrucksäule beteiligt ist, ohne dass die Reinheit des hoch reinen Stickstoffprodukts beeinträchtigt wird und ohne dass der Betriebsdruck der Niederdrucksäule auf die Bedürfnisse des Kältezuführungssystem abgestimmt werden muss. (Ein geeignetes Kältefluid stellt zum Beispiel Stickstoff dar, der noch leichtflüchtige Verunreinigungen enthält.) Im Gegensatz dazu wird bei dem Kältezuführungssystem der bekannten Verfahren eine Restfraktion, zum Beispiel vom Verdampfungsraum des Kopfkondensators, abgezogen, arbeitsleistend auf etwa Atmosphärendruck entspannt und aus dem Verfahren entfernt. Dabei liegt der Mindest-Betriebsdruck des Kopfkondensators und damit derjenige der Niederdrucksäule allein durch das Kältezuführungssystem fest. Dieser Nachteil wird bei der Erfindung vermieden, ohne dabei die Produktreinheit zu verringern.The refrigerant fluid can be formed in the invention by a readily available medium be introduced into the low pressure column and thus the mass transfer involved in the low-pressure column without affecting the purity of the highly pure Nitrogen product is affected and without the operating pressure of the Low pressure column can be tailored to the needs of the refrigeration system got to. (For example, a suitable cryogenic fluid is nitrogen, which is still Contains volatile contaminants.) In contrast, in the Refrigeration supply system of the known method a residual fraction, for example from Evaporation space of the top condenser, deducted, working to about Atmospheric pressure is released and removed from the process. This is the minimum operating pressure the top condenser and thus that of the low pressure column alone through the cold supply system. This disadvantage is in the invention avoided without reducing product purity.

Das Kältefluid wird bei der Erfindung vorzugsweise am Kopf der Niederdrucksäule eingespeist.The refrigerant fluid is in the invention preferably at the top of the low pressure column fed.

In einer ersten Variante der Erfindung wird das Kältefluid aus der Drucksäule entnommen, in dem Kältezuführungssystem arbeitsleistend entspannt und in die Niederdrucksäule eingeleitet.In a first variant of the invention, the refrigerant fluid from the pressure column removed, in the refrigeration supply system work performing relaxed and in the Low pressure column initiated.

Durch die arbeitsleistende Entspannung eines Fluids, insbesondere eines Gases, von Drucksäulen- auf Niederdrucksäulendruck kann auf besonders günstige Weise Verfahrenskälte erzeugt werden. Damit können die Isolations- und Austauschverluste kompensiert und gegebenenfalls kleine Mengen an Produkten verflüssigt werden. Das Kältefluid wird vorzugsweise stromaufwärts seiner arbeitsleistenden Entspannung in indirektem Wärmeaustausch gegen abzukühlende Prozess-Ströme angewärmt.Due to the work-performing expansion of a fluid, in particular a gas from Pressure column on low pressure column pressure can be particularly favorable Process refrigeration are generated. This allows the insulation and replacement losses be compensated and possibly liquefied small amounts of products. The Refrigerant fluid is preferably upstream of its work-performing expansion in Indirect heat exchange against cooled process streams warmed up.

Der Stoffaustauschabschnitt wird durch einen oder mehrere Rektifizierböden (so genannte Sperrböden) gebildet - hierfür gilt die Angabe in "praktischer" Bodenzahl - oder durch einen kurzen Packungsabschnitt ("theoretische" Bodenzahl). Die Zahl der Sperrböden beziehungsweise theoretischen Böden beträgt beispielsweise 1 bis 10, vorzugsweise 2 bis 3. Durch den Abzug der Stickstoffprodukts unterhalb dieser Sperrböden weist das Stickstoffprodukt einen sehr geringen Gehalt an leichtflüchtigen Verunreinigungen auf, die im Kopf der Niederdrucksäule zurückbleiben und von dort mit einem weniger reinen Stickstoffstrom abgezogen werden.The mass transfer section is separated by one or more rectification plates (see above) mentioned floors) - this is the indication in "practical" number of shelves - or by a short packing section ("theoretical" number of plates). The number of For example, barrier floors or theoretical floors amounts to 1 to 10, preferably 2 to 3. By withdrawing the nitrogen product below this Floors, the nitrogen product has a very low content of volatile Contaminants that remain in the head of the low pressure column and from there are withdrawn with a less pure nitrogen stream.

Das Kältefluid enthält regelmäßig leichter als Stickstoff flüchtige Bestandteile. Dank der Einspeisung oberhalb des beschriebenen Stoffaustauschabschnitts gelangen diese jedoch nicht in das weiter unten abgezogenen Stickstoffprodukt.The refrigerant fluid is usually lighter than nitrogen volatile components. thanks to the Infeed above the described mass transfer section get this but not in the further withdrawn nitrogen product.

Es ist günstig, wenn das Kältefluid aus dem oberen Bereich der Drucksäule entnommen wird. Es wird zum Beispiel durch eine stickstoffreiche Gasfraktion aus der Drucksäule gebildet, insbesondere durch deren Kopfgas.It is favorable if the cooling fluid from the upper region of the pressure column is removed. It is characterized by a nitrogen-rich gas fraction from the Pressure column formed, in particular by the head gas.

Gemäß einer zweiten Variante der Erfindung wird das Kältefluid durch eine tiefkalte Flüssigkeit gebildet, die außerhalb des Rektifiziersystems erzeugt wurde.According to a second variant of the invention, the cooling fluid is passed through a deep-cold Liquid formed outside the rectification system.

Durch die Einspeisung externer Flüssigkeit als Kältequelle (Liquid Assist) weist das Verfahren eine besonders hohe Flexibilität auf. Es kann beispielsweise ganz oder teilweise auf Maschinen zur Kälteerzeugung, wie zum Beispiel Entspannungsturbinen, verzichtet werden. Die tiefkalte Flüssigkeit kann beispielsweise durch Flüssigstickstoff gebildet werden, der aus einer anderen Luftzerlegungsanlage stammt; altemativ kann jedes andere Gemisch von Luftkomponenten eingesetzt werden. Die externe Flüssigkeit kann entweder über eine Rohrleitung herangeführt oder aus einem Speicherbehälter entnommen werden. Die Einspeisung erfolgt an derjenigen Stelle, die der Zusammensetzung der externen Flüssigkeit entspricht. Dies kann der obere Bereich der Druck- oder Niederdrucksäule sein.Due to the supply of external liquid as a source of cold (Liquid Assist) has the Process a particularly high flexibility. It can, for example, whole or partly on machines for refrigeration, such as expansion turbines, be waived. The cryogenic liquid can be, for example, by liquid nitrogen formed from another air separation plant; Altematively can any other mixture of air components can be used. The external one Liquid can either be introduced via a pipeline or from a Storage tanks are removed. The feed takes place at the point that the composition of the external fluid corresponds. This can be the top one Be the area of the pressure or low pressure column.

Die tiefkalte Flüssigkeit kann teilweise oder vollständig in die Niederdrucksäule eingeleitet werden, vorzugsweise an deren Kopf. Alternativ oder zusätzlich kann die tiefkalte Flüssigkeit mindestens zum Teil in den oberen Bereich der Drucksäule eingeführt werden.The cryogenic liquid may partially or completely enter the low pressure column are introduced, preferably at the head. Alternatively or additionally, the deep cold liquid at least partially in the upper part of the pressure column be introduced.

Vorzugsweise wird Kältemittel für den Kopfkondensator aus dem unteren Bereich der Niederdrucksäule entnommen, und das gesamte sauerstoffangereicherte Produkt der Drucksäule wird in die Niederdrucksäule eingespeist. Unter "sauerstoffangereichert" wird hier jede Fraktion verstanden, deren Sauerstoffgehalt größer als derjenige der Luft ist. Preferably, refrigerant for the top condenser from the bottom of the Low pressure column removed, and the entire oxygenated product of Pressure column is fed into the low pressure column. Under "oxygenated" here every fraction is understood, whose oxygen content is greater than that of the air is.

Das Stickstoffprodukt kann gasförmig aus der Niederdrucksäule abgezogen werden. Alternativ wird es flüssig aus der Niederdrucksäule entnommen und in indirektem Wärmeaustausch mit arbeitsleistend entspanntem Kältefluid verdampft. Auch eine Kombination dieser beiden Verfahrensschritte ist möglich.The nitrogen product can be withdrawn in gaseous form from the low pressure column. Alternatively, it is taken from the low-pressure column in liquid and in indirect Heat exchange with work-performing expanded refrigerant fluid evaporates. Also one Combination of these two process steps is possible.

Die Erfindung betrifft außerdem eine Vorrichtung gemäß den Patentansprüchen 10 bis 12.The invention also relates to a device according to claims 10 to 12th

Die Erfindung sowie weitere Einzelheiten der Erfindung werden im Folgenden anhand zweier in der Zeichnung dargestellten Ausführungsbeispiele - je eines für jede der beiden Varianten der Erfindung - näher erläutert.The invention and further details of the invention are described below two embodiments shown in the drawing - one for each of the two variants of the invention - explained in more detail.

Verdichtete und gereinigte Luft 1 wird bei dem Ausführungsbeispiel von Figur 1 in einem Hauptwärmetauscher 2 abgekühlt und einer Drucksäule 4 unter einem Druck von 9 bis 13 bar zugeleitet (3). Das Rektifiziersystem weist außerdem eine Niederdrucksäule 5 auf, die mit einem Druck von 2 bis 5 bar betrieben wird und mit der Drucksäule über einen gemeinsamen Kondensator-Verdampfer (Hauptkondensator) 6 in wärmetauschender Verbindung steht. Ein Teil 8 des am Kopf der Drucksäule entnommenen Stickstoffs wird im Hauptkondensator 6 verflüssigt und über die Leitungen 9 und 10 teilweise als Rücklauf auf die Drucksäule aufgegeben. Ein anderer Strom 14 der Flüssigkeit 9 aus dem Hauptkondensator 6 wird unterkühlt (15) und zu einem ersten Teil 20 als Rücklauf der Niederdrucksäule 5 am Kopf zugeführt. Zu einem zweiten Teil 21 wird der unterkühlte Stickstoff als Flüssigprodukt PLIN abgezogen. Sumpfflüssigkeit 11 der Drucksäule wird nach Unterkühlung 15 als sauerstoffhaltige flüssige Fraktion in die Niederdrucksäule 5 eingedrosselt (12).Compressed and purified air 1 is cooled in the embodiment of Figure 1 in a main heat exchanger 2 and a pressure column 4 under a pressure of 9 to 13 bar supplied (3). The rectification system also has a low-pressure column 5 which is operated at a pressure of 2 to 5 bar and is in heat-exchanging communication with the pressure column via a common condenser-evaporator (main condenser) 6. Part 8 of the nitrogen withdrawn at the top of the pressure column is liquefied in the main condenser 6 and partly fed via lines 9 and 10 as reflux to the pressure column. Another stream 14 of the liquid 9 from the main condenser 6 is subcooled (15) and fed to a first part 20 as reflux of the low pressure column 5 at the top. To a second part 21 of the supercooled nitrogen is withdrawn as a liquid product PLIN. Bottom liquid 11 of the pressure column is throttled after supercooling 15 as an oxygen-containing liquid fraction in the low-pressure column 5 (12).

Die Sumpfflüssigkeit 13 der Niederdrucksäule 5 wird ebenfalls unterkühlt (15) und entspannt (16) und anschließend in den Verdampfungsraum des Kopfkondensators 17 der Niederdrucksäule 5 eingeführt. In dessen Verflüssigungsraum kondensiert gasförmiger Stickstoff 18 vom Kopf der Niederdrucksäule 5; das Kondensat 19 wird in die Niederdrucksäule zurückgeleitet und dort als zusätzlicher Rücklauf verwendet. Aus dem unteren Bereich des Verdampfungsraums des Kopfkondensators 17 wird über Leitung 22 kontinuierlich oder intermittierend eine Spülflüssigkeit (PURGE) abgezogen. Der im Kopfkondensator 17 erzeugte Dampf 23 wird in den Wärmetauschem 15 und 2 auf etwa Umgebungstemperatur angewärmt und über Leitung 24 verworfen und/oder als Regeneriergas für eine nicht dargestellte Reinigungsvorrichtung (zum Beispiel Molekularsieb-Station) eingesetzt. Über eine Leitung 35 wird nicht kondensiertes Gas, das insbesondere leichterflüchtige Komponenten enthält, abgezogen. Es wird abgeblasen (36) und/oder dem Dampf 23 zugemischt (37).The bottom liquid 13 of the low-pressure column 5 is also undercooled (15) and relaxed (16) and then into the evaporation space of the top condenser 17th introduced the low pressure column 5. Condensed in the liquefaction space gaseous nitrogen 18 from the top of the low-pressure column 5; the condensate 19 is in the low pressure column returned and used there as an additional return. Out the lower portion of the evaporation space of the top condenser 17 is over Line 22 continuously or intermittently a flushing fluid (PURGE) deducted. The generated in the top condenser 17 steam 23 is in the heat exchanger 15 and the second warmed to about ambient temperature and discarded via line 24 and / or as a regeneration gas for a cleaning device, not shown (for example Molecular sieve station) used. Via a line 35 is not condensed gas, which in particular contains more volatile components, deducted. It will blown off (36) and / or admixed with the steam 23 (37).

Unterhalb des Kopfs der Niederdrucksäule 5 befindet sich ein Stoffaustauschabschnitt 25, der in dem Beispiel durch drei praktische Böden (Sperrböden) gebildet wird. Darunter wird über Leitung 26 gasförmiger Stickstoff als hochreines Produkt entnommen und in den Wärmetauschem 15 und 2 auf etwa Umgebungstemperatur angewärmt. Das warme Stickstoffprodukt 27 kann unmittelbar als Endprodukt (PGAN) verwendet werden, oder es wird - wie in der Zeichnung dargestellt - zunächst in einem Stickstoffverdichter 28 mit Nachkühler 29 weiter komprimiert und schließlich über Leitung 30 abgezogen.Below the head of the low pressure column 5 is a mass transfer section 25, which in the example is formed by three practical floors (barrier floors). Below this is gaseous nitrogen via line 26 as a highly pure product taken and in the heat exchanger 15 and 2 to about ambient temperature warmed up. The warm nitrogen product 27 can be used immediately as a final product (PGAN) be used or it is - as shown in the drawing - first in one Nitrogen compressor 28 with aftercooler 29 further compressed and finally over Deducted line 30.

Über Leitung 31 wird ein Teil des gasförmigen Kopfstickstoffs aus der Drucksäule 4 als Kältefluid abgezogen, im Hauptwärmetauscher 2 auf eine Zwischentemperatur angewärmt und über Leitung 32 einer Entspannungsmaschine 33 zugeführt, die beispielsweise als Generatorturbine ausgebildet ist. Das arbeitsleistend auf etwa Niederdrucksäulendruck entspannte Kältefluid 34 wird dem Kopf der Niederdrucksäule zugeführt, also oberhalb der Sperrböden 25 eingespeist. Diese Verfahrensschritte beziehungsweise die dazu verwendeten Vorrichtungsteile bilden ein "Kältezuführungssystem" gemäß der ersten Variante der Erfindung.Via line 31, a portion of the gaseous nitrogen head from the pressure column 4 as Refrigerant withdrawn, in the main heat exchanger 2 to an intermediate temperature warmed and fed via line 32 to a relaxation machine 33, the is designed for example as a generator turbine. Doing work on about Low-pressure column pressure relaxed refrigerant fluid 34 is the head of the low-pressure column supplied, ie fed above the barrier floors 25. These process steps or the device parts used for this purpose form a "Refrigerant supply system" according to the first variant of the invention.

Alternativ oder zusätzlich kann in dem "Kältezuführungssystem" gemäß der ersten Variante der Erfindung Stickstoff als Kältefluid auf über Drucksäulen-Druck verdichtet, arbeitsleistend entspannt und in die Drucksäule (vorzugsweise am Kopf) eingespeist werden (in der Zeichnung nicht dargestellt).Alternatively or additionally, in the "refrigeration supply system" according to the first Variant of the invention Nitrogen as refrigerant fluid compressed to over pressure column pressure, Work-relaxed and fed into the pressure column (preferably on the head) are (not shown in the drawing).

Bei Ausfall der Turbine 33 kann die Anlage im Notbetrieb gefahren werden, indem eine tiefkalte Flüssigkeit (38) von außerhalb des Rektifiziersystems in eine der Säulen des Rektifiziersystems eingeleitet wird ("Liquid Assist"), wie es in Figur 2 im Detail erläutert ist. Im Unterschied zu der letztgenannten Patentanmeldung muss die tiefkalte Flüssigkeit nicht unbedingt außerhalb des Rektifiziersystems erzeugt worden sein; vielmehr kann für den Notbetrieb auch Flüssigkeit (zum Beispiel flüssiger Stickstoff) verwendet werden, der während des Normalbetriebs der Anlage erzeugt und in einem Speichertank gelagert wird.In case of failure of the turbine 33, the system can be run in emergency mode by a cryogenic liquid (38) from outside the rectification system into one of the columns of the Rectification is initiated ("Liquid Assist"), as explained in Figure 2 in detail is. In contrast to the last-mentioned patent application must the cryogenic Liquid may not necessarily have been generated outside the rectification system; rather, liquid can also be used for emergency operation (for example, liquid nitrogen) used during normal operation of the plant and in one Storage tank is stored.

Das Ausführungsbeispiel von Figur 1 kann so abgewandelt werden, dass in der Niederdrucksäule ein gasförmiges und/oder flüssiges Sauerstoffprodukt erzeugt wird. Dazu wird nur ein Teil der Sumpfflüssigkeit 11 der Drucksäule nach Unterkühlung 15 als sauerstoffhaltige flüssige Fraktion in die Niederdrucksäule 5 eingedrosselt; ein anderer Teil wird vor dem Ventil 12 abgezweigt und in den Verdampfungsraum des Kopfkondensators 17 geleitet. Die Einspeisung 16 von Sumpfflüssigkeit der Niederdrucksäule in diesen Verdampfungsraum entfällt ganz oder teilweise. Aus dem Sumpfbereich der Niederdrucksäule 5 wird das Sauerstoffprodukt gasförmig und/oder flüssig abgezogen.The embodiment of Figure 1 can be modified so that in the Low pressure column, a gaseous and / or liquid oxygen product is generated. For this purpose, only a part of the bottom liquid 11 of the pressure column after supercooling 15th as oxygen-containing liquid fraction throttled into the low-pressure column 5; on another part is branched off before the valve 12 and into the evaporation space of the Head condenser 17 passed. The feed 16 of bottoms of the Low pressure column in this evaporation space is omitted in whole or in part. From the Sump area of the low-pressure column 5, the oxygen product is gaseous and / or withdrawn liquid.

Verdichtete und gereinigte Luft 1 wird bei dem Ausführungsbeispiel von Figur 2 in einem Hauptwärmetauscher 2 abgekühlt und einer Drucksäule 4 unter einem Druck von 9 bis 10 bar zugeleitet (3). Das Rektifiziersystem weist außerdem eine Niederdrucksäule 5 auf, die mit einem Druck von 2 bis 3 bar betrieben wird und mit der Drucksäule über einen gemeinsamen Kondensator-Verdampfer (Hauptkondensator) 6 in wärmetauschender Verbindung steht. Der am Kopf der Drucksäule entnommene Stickstoff 8 wird im Hauptkondensator 6 verflüssigt und über die Leitungen 9 und 10 teilweise als Rücklauf auf die Drucksäule aufgegeben. Ein anderer Teil 14 der Flüssigkeit 9 aus dem Hauptkondensator 6 wird unterkühlt (15) und zu einem ersten Teil 20 als Rücklauf der Niederdrucksäule 5 am Kopf zugeführt. Zu einem zweiten Teil 21 wird der unterkühlte Stickstoff als Flüssigprodukt PLIN abgezogen. Sumpfflüssigkeit 11 der Drucksäule wird nach Unterkühlung 15 als sauerstoffhaltige flüssige Fraktion in die Niederdrucksäule 5 eingedrosselt (12).Compressed and cleaned air 1 is cooled in the embodiment of Figure 2 in a main heat exchanger 2 and a pressure column 4 under a pressure of 9 to 10 bar supplied (3). The rectification system also has a low-pressure column 5 which is operated at a pressure of 2 to 3 bar and is in heat-exchanging communication with the pressure column via a common condenser-evaporator (main condenser) 6. The withdrawn at the top of the pressure column nitrogen 8 is liquefied in the main condenser 6 and partially abandoned via lines 9 and 10 as reflux to the pressure column. Another part 14 of the liquid 9 from the main condenser 6 is subcooled (15) and fed to a first part 20 as reflux of the low pressure column 5 at the top. To a second part 21 of the supercooled nitrogen is withdrawn as a liquid product PLIN. Bottom liquid 11 of the pressure column is throttled after supercooling 15 as an oxygen-containing liquid fraction in the low-pressure column 5 (12).

Die Sumpfflüssigkeit 13 der Niederdrucksäule 5 wird ebenfalls unterkühlt (15) und entspannt (16) und anschließend in den Verdampfungsraum des Kopfkondensators 17 der Niederdrucksäule 5 eingeführt. In dessen Verflüssigungsraum kondensiert gasförmiger Stickstoff 18 vom Kopf der Niederdrucksäule 5; das Kondensat 19 wird in die Niederdrucksäule zurückgeleitet und dort als zusätzlicher Rücklauf verwendet. Aus dem unteren Bereich des Verdampfungsraums des Kopfkondensators 17 wird über Leitung 22 kontinuierlich oder intermittierend eine Spülflüssigkeit (PURGE) abgezogen. Der im Kopfkondensator 17 erzeugte Dampf 23 wird in den Wärmetauschem 15 und 2 auf etwa Umgebungstemperatur angewärmt und über Leitung 24 verworfen und/oder als Regeneriergas für eine nicht dargestellte Reinigungsvorrichtung (zum Beispiel Molekularsieb-Station) eingesetzt. Über eine Leitung 35 wird nicht kondensiertes Gas, das insbesondere leichterflüchtige Komponenten enthält, abgezogen. Es wird abgeblasen (36) und/oder dem Dampf 23 zugemischt (37).The bottom liquid 13 of the low-pressure column 5 is also undercooled (15) and relaxed (16) and then into the evaporation space of the top condenser 17th introduced the low pressure column 5. Condensed in the liquefaction space gaseous nitrogen 18 from the top of the low-pressure column 5; the condensate 19 is in the low pressure column returned and used there as an additional return. Out the lower portion of the evaporation space of the top condenser 17 is over Line 22 continuously or intermittently a flushing fluid (PURGE) deducted. The generated in the top condenser 17 steam 23 is in the heat exchanger 15 and the second warmed to about ambient temperature and discarded via line 24 and / or as a regeneration gas for a cleaning device, not shown (for example Molecular sieve station) used. Via a line 35 is not condensed gas, which in particular contains more volatile components, deducted. It will blown off (36) and / or admixed with the steam 23 (37).

Unterhalb des Kopfs der Niederdrucksäule 5 befindet sich ein Stoffaustauschabschnitt 25, der in dem Beispiel durch drei praktische Böden (Sperrböden) gebildet wird. Darunter wird über Leitung 26 gasförmiger Stickstoff als hochreines Produkt entnommen und in den Wärmetauschem 15 und 2 auf etwa Umgebungstemperatur angewärmt. Das warme Stickstoffprodukt 27 kann unmittelbar als Endprodukt (PGAN) verwendet werden, oder es wird - wie in der Zeichnung dargestellt - zunächst in einem Stickstoffverdichter 28 mit Nachkühler 29 weiter komprimiert und schließlich über Leitung 30 abgezogen.Below the head of the low pressure column 5 is a mass transfer section 25, which in the example is formed by three practical floors (barrier floors). Below this is gaseous nitrogen via line 26 as a highly pure product taken and in the heat exchanger 15 and 2 to about ambient temperature warmed up. The warm nitrogen product 27 can be used immediately as a final product (PGAN) be used or it is - as shown in the drawing - first in one Nitrogen compressor 28 with aftercooler 29 further compressed and finally over Deducted line 30.

Über Leitung 38 wird flüssiger Stickstoff, der nicht in einer der Säulen 4, 5 des Rektifiziersystems hergestellt wurde, dem Kopf der Niederdrucksäule - also oberhalb der Sperrböden 25 - zugeführt. Diese tiefkalte Flüssigkeit wird in dem Beispiel einem Speichertank 39 entnommen, der aus einer externen Quelle befüllt wird, beispielsweise mittels Tankwagen. Diese Verfahrensschritte beziehungsweise die dazu verwendeten Vorrichtungsteile bilden ein "Kältezuführungssystem" gemäß der zweiten Variante der Erfindung.Via line 38 is liquid nitrogen, not in one of the columns 4, 5 of the Rectification was made, the head of the low-pressure column - ie above the barrier floors 25 - supplied. This cryogenic liquid becomes one in the example Storage tank 39 removed, which is filled from an external source, for example by tanker. These process steps or the used for it Device parts form a "refrigeration supply system" according to the second variant of Invention.

Alternativ oder zusätzlich kann in dem "Kältezuführungssystem" gemäß der zweiten Variante der Erfindung flüssiger Stickstoff aus dem Speichertank 39 als Kältefluid in die Drucksäule (vorzugsweise am Kopf) eingespeist werden (in der Zeichnung nicht dargestellt).Alternatively or additionally, in the "cold supply system" according to the second Variant of the invention liquid nitrogen from the storage tank 39 as a refrigerant fluid in the Pressure column (preferably on the head) are fed (not in the drawing ) Shown.

Das Ausführungsbeispiel von Figur 2 kann so abgewandelt werden, dass in der Niederdrucksäule ein gasförmiges und/oder flüssiges Sauerstoffprodukt erzeugt wird. Dazu wird nur ein Teil der Sumpfflüssigkeit 11 der Drucksäule nach Unterkühlung 15 als sauerstoffhaltige flüssige Fraktion in die Niederdrucksäule 5 eingedrosselt; ein anderer Teil wird vor dem Ventil 12 abgezweigt und in den Verdampfungsraum des Kopfkondensators 17 geleitet. Die Einspeisung 16 von Sumpfflüssigkeit der Niederdrucksäule in diesen Verdampfungsraum entfällt ganz oder teilweise. Aus dem Sumpfbereich der Niederdrucksäule 5 wird das Sauerstoffprodukt gasförmig und/oder flüssig abgezogen.The embodiment of Figure 2 can be modified so that in the Low pressure column, a gaseous and / or liquid oxygen product is generated. For this purpose, only a part of the bottom liquid 11 of the pressure column after supercooling 15th as oxygen-containing liquid fraction throttled into the low-pressure column 5; on another part is branched off before the valve 12 and into the evaporation space of the Head condenser 17 passed. The feed 16 of bottoms of the Low pressure column in this evaporation space is omitted in whole or in part. From the Sump area of the low-pressure column 5, the oxygen product is gaseous and / or withdrawn liquid.

Claims (12)

Verfahren zur Gewinnung von hoch reinem Stickstoff durch Tieftemperaturzerlegung von Luft in einem Rektifiziersystem, das eine Drucksäule (4) und eine Niederdrucksäule (5) aufweist, wobei bei dem Verfahren Einsatzluft (1, 3) in die Drucksäule (4) eingeleitet, eine sauerstoffhaltige flüssige Fraktion (11) aus der Drucksäule (4) entnommen und in die Niederdrucksäule (5) eingespeist wird, gasförmiger Stickstoff (18) oberhalb eines Stoffaustauschabschnitts (25), der mindestens einen theoretischen beziehungsweise praktischen Boden aufweist, aus der Niederdrucksäule (5) abgezogen und in einem Kopfkondensator (17) durch indirekten Wärmeaustausch mit einem Kältemittel (13) mindestens teilweise kondensiert wird und hoch reiner Stickstoff (26, 27, 30) unterhalb des Stoffaustauschabschnitts (25) aus der Niederdrucksäule (5) entnommen wird, dadurch gekennzeichnet, dass das Verfahren ein Kältezuführungssystem aufweist, in dem ein Kältefluid (31, 32, 34; 38) strömt und mindestens ein Teil des Kältefluids aus dem Kältezuführungssystem oberhalb des Stoffaustauschabschnitts (25) in die Niederdrucksäule (5) oder in den oberen Bereich der Drucksäule (4) eingeleitet (34; 38) wird.A process for the recovery of high purity nitrogen by cryogenic separation of air in a rectification system comprising a pressure column (4) and a low pressure column (5), wherein in the process feed air (1, 3) is introduced into the pressure column (4), an oxygenated liquid Fraction (11) is taken from the pressure column (4) and fed into the low-pressure column (5), gaseous nitrogen (18) above a mass transfer section (25) having at least one theoretical or practical bottom, deducted from the low pressure column (5) and in a top condenser (17) by indirect heat exchange with a refrigerant (13) is at least partially condensed and high purity nitrogen (26, 27, 30) is removed below the mass transfer section (25) from the low pressure column (5), characterized in that the Method has a cold supply system in which a cooling fluid (31, 32, 34, 38) flows and at least one Part of the refrigerant from the cold supply system above the mass transfer section (25) in the low-pressure column (5) or in the upper region of the pressure column (4) initiated (34; 38). Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass das Kältefluid aus der Drucksäule (4) entnommen, in dem Kältezuführungssystem arbeitsleistend entspannt (33) und in die Niederdrucksäule (5) eingeleitet (34) wirdA method according to claim 1, characterized in that the refrigerant fluid from the pressure column (4) taken in the cold supply system work expanded (33) and in the low pressure column (5) introduced (34) Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass das Kältefluid (31) aus dem oberen Bereich der Drucksäule (4) entnommen wird.A method according to claim 2, characterized in that the refrigerant fluid (31) from the upper region of the pressure column (4) is removed. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das Kältefluid durch eine tiefkalte Flüssigkeit (38) gebildet wird, die außerhalb des Rektifiziersystems erzeugt wurde.Method according to one of claims 1 to 3, characterized in that the refrigerant fluid is formed by a cryogenic liquid (38) which has been generated outside of the rectification system. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass die tiefkalte Flüssigkeit teilweise oder vollständig in die Niederdrucksäule (5) eingeleitet wird. A method according to claim 4, characterized in that the cryogenic liquid is partially or completely introduced into the low-pressure column (5). Verfahren nach der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass Kältemittel (13) für den Kopfkondensator (17) aus dem unteren Bereich der Niederdrucksäule (5) entnommen wird.Method according to claims 1 to 5, characterized in that refrigerant (13) for the top condenser (17) is taken from the lower region of the low-pressure column (5). Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass das gesamte sauerstoffangereicherte Produkt (11) der Drucksäule (4) in die Niederdrucksäule (5) eingespeist (12) wird.Method according to one of claims 1 to 6, characterized in that the entire oxygen-enriched product (11) of the pressure column (4) in the low-pressure column (5) is fed (12). Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass das Stickstoffprodukt (26) mindestens teilweise gasförmig aus der Niederdrucksäule (5) abgezogen wird.Method according to one of claims 1 to 7, characterized in that the nitrogen product (26) is at least partially withdrawn in gaseous form from the low-pressure column (5). Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass das Stickstoffprodukt mindestens teilweise flüssig aus der Niederdrucksäule abgezogen und in indirektem Wärmeaustausch mit arbeitsleistend entspanntem Kältefluid verdampft wird.Method according to one of claims 1 to 8, characterized in that the nitrogen product is at least partially withdrawn liquid from the low pressure column and evaporated in indirect heat exchange with work-performing expanded refrigerant fluid. Vorrichtung zur Gewinnung von Stickstoff durch Tieftemperaturzerlegung von Luft in einem Rektifiziersystem, das eine Drucksäule (4) und eine Niederdrucksäule (5) aufweist, mit einer Einsatzluftleitung (1, 3), die in die Drucksäule (4) führt, mit einer Leitung (11) für eine sauerstoffhaltige flüssige Fraktion, die von der Drucksäule (4) in die Niederdrucksäule (5) führt, mit einem Kopfkondensator (17), dessen Verflüssigungsseite mit einem Bereich der Niederdrucksäule (5) oberhalb eines Stoffaustauschabschnitts (25), der mindestens einen theoretischen beziehungsweise praktischen Boden aufweist, verbunden (18) ist, und mit einer Stickstoffproduktleitung (26, 27, 30) zur Entnahme hoch reinen Stickstoffs, die unterhalb des Stoffaustauschabschnitts (25) mit der Niederdrucksäule (5) verbunden ist, gekennzeichnet durch ein Kältezuführungssystem, das eine Kältefluidleitung (31, 32, 34; 38) aufweist, die oberhalb des Stoffaustauschabschnitts (25) mit der Niederdrucksäule (5) verbunden ist.Apparatus for recovering nitrogen by cryogenic separation of air in a rectification system comprising a pressure column (4) and a low pressure column (5), with a feed air line (1, 3) leading into the pressure column (4) with a conduit (11 ) for an oxygen-containing liquid fraction, which leads from the pressure column (4) in the low-pressure column (5), with a top condenser (17) whose liquefaction side with a region of the low-pressure column (5) above a mass transfer section (25), the at least one theoretical (18) and with a nitrogen product line (26, 27, 30) for removing high-purity nitrogen, which is connected below the mass transfer section (25) to the low-pressure column (5), characterized by a refrigeration feed system a refrigeration fluid line (31, 32, 34; 38) which above the mass transfer section (25) with the low pressure column (5) verb is unden. Vorrichtung nach Anspruch 10, dadurch gekennzeichnet, dass das Kältezuführungssystem eine Entspannungsmaschine (33) aufweist, deren Eintritt mit der Drucksäule (4) verbunden (11, 32) ist und deren Austritt mit der Kältefluidleitung (31, 32, 34; 38) verbunden (34) ist. Apparatus according to claim 10, characterized in that the cold supply system comprises a relaxation machine (33), the inlet of which is connected to the pressure column (4) (11, 32) and whose outlet is connected to the refrigerant fluid line (31, 32, 34; 34). Vorrichtung nach Anspruch 10 oder 11, dadurch gekennzeichnet, dass die Kältefluidleitung als Flüssigkeitsleitung (38) zur Einspeisung einer tiefkalten Flüssigkeit, die außerhalb des Rektifiziersystems erzeugt wurde, ausgebildet ist.Apparatus according to claim 10 or 11, characterized in that the refrigerant fluid line as a liquid line (38) for feeding a cryogenic liquid which has been generated outside the rectification system, is formed.
EP02022022A 2001-10-04 2002-10-01 Process and device for producing ultra-high purity Nitrogen by cryogenic separation of air Withdrawn EP1300640A1 (en)

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DE10148820 2001-10-04
DE2001148820 DE10148820A1 (en) 2001-10-04 2001-10-04 Nitrogen recovery by low temperature rectification of air uses cold fluid from flowing supply system for condensing nitrogen gas taken above substance exchange section of low pressure column
DE10148818A DE10148818A1 (en) 2001-10-04 2001-10-04 Nitrogen recovery by low temperature rectification of air uses cold fluid from flowing supply system for condensing nitrogen gas taken above substance exchange section of low pressure column
DE10148818 2001-10-04

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