EP0709632B1 - Lufttrennungsverfahren und Vorrichtung zur Herstellung von Stickstoff - Google Patents

Lufttrennungsverfahren und Vorrichtung zur Herstellung von Stickstoff Download PDF

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Publication number
EP0709632B1
EP0709632B1 EP95307528A EP95307528A EP0709632B1 EP 0709632 B1 EP0709632 B1 EP 0709632B1 EP 95307528 A EP95307528 A EP 95307528A EP 95307528 A EP95307528 A EP 95307528A EP 0709632 B1 EP0709632 B1 EP 0709632B1
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Prior art keywords
stream
vapour
distillation column
air
oxygen
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EP95307528A
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English (en)
French (fr)
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EP0709632A3 (de
EP0709632A2 (de
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Robert A. Mostello
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BOC Group Ltd
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BOC Group Ltd
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Priority claimed from US08/459,946 external-priority patent/US5507148A/en
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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
    • F25J3/04151—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
    • F25J3/0423—Subcooling of liquid process streams
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/044—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a single pressure main column system only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/50—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/72—Refluxing the column with at least a part of the totally condensed overhead gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • F25J2240/48—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval the fluid being oxygen enriched compared to air, e.g. "crude 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/02—Internal refrigeration with liquid vaporising loop

Definitions

  • the present invention relates to a method and apparatus for separating air by low temperature rectification employing a distillation column so as to produce a nitrogen product.
  • Nitrogen is produced by low temperature rectification of air in an air separation plant. Often such plants employ a single distillation column and are known in the art as nitrogen generators. After air has been filtered, compressed and purified, the air is cooled to a temperature suitable for its rectification. This temperature is normally at or near the dew point of the air. Thereafter, the air is introduced into a distillation column having liquid-vapour contacting elements which may comprise trays and/or packings, either structured or random. In the distillation column an ascending vapour phase is contacted by a descending liquid phase. The result of such contact is that the liquid becomes evermore concentrated in oxygen to produce an oxygen enriched bottom liquid fraction and the vapour becomes evermore concentrated in nitrogen to produce a nitrogen rich head vapour fraction.
  • a head condenser In order to provide reflux the column, a head condenser is provided in which the nitrogen vapour fraction is partially condensed.
  • the condensate is returned to the distillation column as reflux.
  • a stream of the oxygen-rich liquid is removed, is expanded to a low temperature, and is then used as the coolant for the head condenser.
  • the nitrogen product is removed from the top region of the column as vapour.
  • the present invention relates to an air separation method and apparatus in which refrigeration is generated in a manner that reduces the energy expenditure in producing a nitrogen product.
  • a method of separating air to produce a nitrogen product comprising the features of claim 1.
  • an apparatus for separating air to produce a nitrogen product comprising the features of claim 5.
  • an apparatus for separating air to produce a nitrogen product comprising the features of claim 6.
  • the present invention functions in all its aspects by taking advantage of the larger-than-necessary driving forces that are employed in the distillation of air to create the nitrogen product.
  • the oxygen enriched liquid acts as a coolant for condensing reflux to the column and serves to supply at least part of the refrigeration needs of the plant, independent of aforementioned typical refrigeration processes.
  • the present invention encompasses a method in which the oxygen enriched liquid stream or a part thereof is partially or wholly vaporised by indirectly exchanging heat with part of the air to be separated and, preferably, with another vapour stream withdrawn from the column of lesser oxygen content than air, thereby causing the part of the air to be separated and if present, the other vapour stream to liquefy.
  • the part of the air to be separated and, preferably, the other liquefied vapour stream withdrawn from the column are then introduced into the distillation column as intermediate reflux streams to maintain production of the product stream at a level that would have been obtained had the entire oxygen rich liquid stream been utilised to condense the at least part of the nitrogen rich vapour tower overhead.
  • the oxygen enriched liquid is preferably expanded to produce a temperature difference for the indirect heat exchange with the part of the air and preferably, if present, the vapour stream withdrawn from the column.
  • the present functions in all its aspects by taking advantage of the larger-than-necessary driving forces that are employed in the distillation of air.
  • a single column nitrogen generator 10 is illustrated.
  • An incoming air stream 12 is filtered by a filter 14 to remove dust particles and the like.
  • Air stream 12 after having been filtered, is compressed by a compressor 16 and thereafter, the heat of compression is removed by a conventional after-cooler 18.
  • Water, carbon dioxide and heavy trace components of the air such as hydrocarbons are removed by a conventional pre-purification unit 20 connected to or otherwise communicating with aftercooler 18.
  • Pre-purification unit 20 can comprise several beds of adsorbent operating out of phase for regeneration purposes.
  • Air stream 12 having thus been filtered, compressed and purified is then introduced into a main heat exchanger 22 and is fully cooled by passage therethrough to a temperature suitable for its rectification.
  • the term “fully cooled” as used herein means cooled to a temperature at which the rectification is conducted.
  • the term “fully warmed” as used herein means warmed to a warm end temperature of main heat exchanger 22.
  • the term “partially warmed” means warmed in the heat exchanger 22 to a temperature above the rectification temperature but below the temperature of the warm end of main heat exchanger 22.
  • First subsidiary stream 24 constitutes a major portion of the air to be separated and is introduced into a single distillation column 30 which is provided by liquid-vapour contacting elements 32, 34 and 36 which can be trays and/or structured packing, and/or random packing.
  • Distillation column 30 rectifies the incoming air into an oxygen rich liquid fraction that collects within bottom region 38 of distillation column 30 and a nitrogen rich head vapour fraction which collects in a top region 40 of distillation column 30.
  • a head condenser 42 is connected to or otherwise communicates with distillation column 30 to condense at least part of the nitrogen rich vapour fraction.
  • a nitrogen vapour stream 44 flows out of the top region 40 of distillation column 30 and is introduced into head condenser 42.
  • Nitrogen vapour stream 44 is in part condensed by a coolant stream 46, which in turn vaporises to produce a vaporised coolant stream 47. After condensation, nitrogen vapour stream 44 is returned as a reflux stream 48 to top region 40 of distillation column 30.
  • An oxygen enriched liquid stream 50 flows from bottom region 38 of distillation column 30.
  • Oxygen enriched liquid stream 50 can then be preferably subcooled within a subcooler unit 52 to minimise vapour formation upon subsequent valve expansion.
  • oxygen enriched liquid stream 50 is partially vaporised within a vaporiser 54 after having passed through a pressure reduction valve 55 and then introduced into a phase separator 56 to separate oxygen enriched liquid stream 50 into liquid and vapour phases.
  • a liquid phase stream 58 flows from phase separator 56 through a pressure reduction valve 60.
  • liquid phase stream 58 after passage through pressure reduction valve 60 forms the aforementioned coolant stream 46.
  • Phase separator 56 is also connected to or otherwise communicates with the main heat exchanger 22 so that a vapour phase stream 62 partially warms within main heat exchanger 22.
  • Vapour phase stream 62 after having been partially warmed is expanded in a turboexpander 64 or other expansion machine connected to or otherwise communicating with main heat exchanger 22.
  • the expansion of vapour phase stream 62 produces refrigeration in the form of a refrigerant stream 66.
  • the refrigerant stream 66 is warmed within subcooler unit 52, as is vaporised coolant stream 47 and a product stream 68, by countercurrent indirect heat exchange with the oxygen enriched liquid stream 50 which is thereby sub-cooled.
  • the vaporised coolant stream 47 after subcooler unit 52, fully warms within main heat exchanger 22 to form a waste stream labelled WN 1 in Figure 1. Part of warm vaporised coolant stream 47 can be fed to pre-purification unit 20 for bed regeneration purposes.
  • Main heat exchanger 22 is in communication with turboexpander 64 so that refrigerant stream 66 eventually fully warms within main heat exchanger 22 and is discharged as a waste stream, designated as WN 2 in Figure 1.
  • a product stream 68 is taken from the nitrogen vapour head fraction collected in top region 40 of distillation column 30. After being warmed in subcooling unit 52, product stream 68 flows through main heat exchanger 22 and is discharged as a fully warmed product stream, labelled PN.
  • oxygen enriched liquid stream 50 is partially vaporised in vaporiser 54 and thus only part of oxygen enriched liquid stream 50 is used as coolant for head condenser 42.
  • a nitrogen generator of the present invention would have a lower production rate and/or produce nitrogen at a lower purity than a prior art generator but with a substantial power saving.
  • compensation for such reduced reflux is effected by the provision of an intermediate reflux stream or streams introduced into lower portions of distillation column 30 where additional liquid reflux is particularly needed.
  • the intermediate reflux allows single column nitrogen generator 10 to achieve the same production rate and product purity as could be expected from a comparable prior art plant design.
  • second subsidiary air stream 26 is liquefied within vaporiser 54.
  • pressure reduction valve 55 is provided to reduce the pressure and thereby the temperature of oxygen enriched liquid stream 50. This reduction in pressure of oxygen enriched liquid stream 50 is below the pressure of distillation column 30 and yet results in a sufficient pressure for oxygen enriched liquid stream 50 that vapour stream 62, derived therefrom, can serve in a refrigeration role.
  • additional reflux to distillation column 30 is produced by liquefaction of a vapour stream 72 extracted from distillation column 30 at about the same point as second stream 26, after liquefaction, is introduced into distillation column 30.
  • Vapour stream 72 is then liquefied within vaporiser 54 and introduced as additional reflux above the point of introduction of the liquefied second subsidiary stream 26.
  • pressure reduction valve 55 also serves to provide a temperature difference between oxygen enriched liquid stream 50 and vapour stream 72.
  • a possible variation to apparatus 10 involves operation of distillation column 30 at high pressure.
  • an expansion machine might also be employed to expand to coolant stream 46. This would increase total plant refrigeration and therefore the amount of liquid produced.
  • turboexpander could also be used to drive a recycle compressor to recycle part of the oxygen enriched liquid contained within coolant stream 46 back into distillation column 30 to increase production.
  • partial vaporisation of oxygen enriched liquid stream 50 may be effected in other ways than through liquefaction of a portion of the incoming air. For instance, in a low pressure column application, a stream from the column, not having the exact composition of liquid air, could be used in place of liquefied air.
  • oxygen rich stream 50 after being subcooled within sub-cooler unit 52 is divided into first and second partial streams 50a and 50b.
  • First partial stream 50a is expanded in first pressure reduction valve 60 to form coolant stream 46.
  • Second partial stream 50b after having been expanded by pressure reduction valve 55 is then fully vaporised within vaporiser 54.
  • the fully vaporised stream designated by reference number 63, is then partially warmed within main heat exchanger 22 and expanded within turboexpander 64.
  • Second partial stream 26 after having been liquefied is added to the distillation column at about six theoretical stages from the bottom.
  • Stream 72 is withdrawn from the distillation column at a point of about six theoretical stages from the bottom and returned after condensing to a point about sixteen theoretical stages from the bottom of distillation column 30.
  • stream 12 In a comparable prior art design making a gaseous nitrogen product, identical in quantity, fractional recovery from air, purity and pressure, where a turboexpander makes refrigeration by expanding air into the distillation column, stream 12 would normally be compressed to about 3.94 bar(a). In Example 1, the air is compressed to about 3.45 bar(a). Accordingly, the method and apparatus according to respectively the first and third aspects of the invention make possible a substantial power saving.
  • Second partial stream 26 after having been liquefied is added to the distillation column at about six theoretical stages from the bottom.
  • Stream 72 is withdrawn from the distillation column at a point of about six theoretical stages from the bottom and returned after condensing to a point about sixteen theoretical stages from the bottom of distillation column 30.
  • Example 2 the pressure of the stream 24 is 3.10 bar and is therefore even less than in Example 1.

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

Claims (6)

  1. Verfahren zum Trennen von Luft zur Erzeugung eines Stickstoffprodukts, das umfaßt:
    Trennen eines ersten Teils der Luft durch Niedertemperatur-Rektifizierung in einer Destillationssäule zum Erzeugen einer sauerstoffreichen Flüssigkeitsfraktion am Boden und einer stickstoffreichen Dampffraktion im Kopf und Kondensieren eines Teils der stickstoffreichen Fraktion in einem Kopfkondensator zum Erzeugen eines Rückflusses für die Destillationssäule,
    teilweises Verdampfen eines Stroms der Sauerstoff-angereicherten Flüssigkeitsfraktion durch indirekten Wärmeaustausch mit einem zweiten Teil der Luft, wodurch der zweite Teil der Luft verflüssigt wird,
    Trennen des Sauerstoff-angereicherten Flüssigkeitsstroms in eine Flüssigkeitsphase und eine Dampfphase,
    Expandieren eines Stroms der Flüssigkeitsphase zum Erzeugen einer Temperaturdifferenz zwischen dem Flüssigkeitsphasenstrom und der stickstoffreichen Dampffraktion, und Einleiten des Flüssigkeitsphasenstroms als Kühlmittelstrom in den Kopfkondensator, so daß Wärme von diesem Teil des stickstoffreichen Dampfes auf den Kühlmittelstrom übertragen und dadurch die Kondensation dieses Teils des stickstoffreichen Dampfes bewirkt wird,
    Expandieren eines Stroms der Dampfphase unter Arbeitsleistung 0zum Erzeugen von Kühlleistung für das Verfahren,
    Ausziehen eines Produktstroms aus einem verbleibenden Teil der stickstoffreichen Dampffraktion zur Bildung des Stickstoffprodukts,
    Einleiten des so verflüssigten zweiten Teils der Luft in die Destillationssäule als Zwischenrückfluß,
    Expandieren des Sauerstoff-angereicherten Flüssigkeitsstroms stromauf der teilweisen Verdampfung des Sauerstoff-angereicherten Flüssigkeitsstroms zum Erzeugen einer Temperaturdifferenz für den indirekten Wärmeaustausch zwischen dem zweiten Teil der Luft und der Sauerstoff-angereicherten Flüssigkeit,
    Abziehen eines Dampfstroms aus einem Zwischenbereich der Destillationssäule, wobei der Dampfstrom einen geringeren Sauerstoffgehalt als Luft hat,
    Kondensieren des Dampfstroms durch indirekten Wärmeaustausch zwischen dem Dampfstrom und dem zweiten Teilstrom, und
    Einleiten des kondensierten Dampfstroms zurück in die Destillationssäule oberhalb des Zwischenrückflusses als zusätzlichen Rückfluß.
  2. Verfahren nach Anspruch 1, wobei der Strom der Sauerstoff-angereicherten Flüssigkeitsfraktion stromauf seiner teilweisen Verdampfung in einer Unterkühleinheit unterkühlt wird.
  3. Verfahren zum Trennen von Luft zum Erzeugen eines Stickstoffprodukts, welches umfaßt:
    Trennen eines ersten Teils der Luft durch Niedertemperatur-Rektifizierung in einer Destillationssäule zum Erzeugen einer sauerstoffreichen Flüssigkeitsfraktion am Boden und einer stickstoffreichen Dampffraktion im Kopf und Kondensieren eines Teils der stickstoffreichen Dampffraktion im Kopf in einem Kopfkondensator zum Erzeugen eines Rückflusses für die Destillationssäule,
    Aufteilen des Stroms der sauerstoffreichen Flüssigkeit in einen ersten und einen zweiten Teilstrom,
    Expandieren des ersten Teilstroms zum Erzeugen einer Temperaturdifferenz zwischen dem ersten Teilstrom und der stickstoffreichen Dampffraktion und Einleiten des expandierten ersten Teilstroms als Kühlmittelstrom in den Kopfkondensator, so daß Wärme von diesem Teil des stickstoffreichen Dampfes im Kopf auf den Kühlmittelstrom übertragen und dadurch die Kondensation dieses Teils des stickstoffreichen Dampfes bewirkt wird,
    Verdampfen des zweiten Teilstroms durch indirekten Wärmeaustausch mit einem zweiten Teil der Luft, wodurch der zweite Teil der Luft verlüssigt wird,
    Expandieren des verdampfen zweiten Teilstroms unter Arbeitsleistung zum Erzeugen von Kühlleistung für das Verfahren,
    Ausziehen eines Produktstroms aus einem verbleibenden Teil des stickstoffreichen Dampfes zum Bilden des Stickstoffprodukts,
    Einleiten des verflüssigten zweiten Teils der Luft in die Destillationssäule als Zwischenrückfluß,
    Expandieren des zweiten Teilstroms stromauf der Verdampfung des zweiten Teilstroms zum Erzeugen einer Temperaturdifferenz für den indirekten Wärmeaustausch zwischen den zweiten Teil der Luft und dem zweiten Teilstrom,
    Abziehen eines Dampfstroms aus einem Zwischenbereich der Destillationssäule, wobei der Dampfstrom einen geringeren Sauerstoffgehalt als Luft hat,
    Kondensieren des Dampfstroms durch indirekten Wärmeaustausch zwischen dem Dampfstrom und dem zweiten Teilstrom, und
    Einleiten des kondensierten Dampfstroms zurück in die Destillationssäule oberhalb des Zwischenrückflusses als zusätzlichen Rückfluß.
  4. Verfahren nach Anspruch 3, wobei
    der Strom der Sauerstoff-angereicherten Flüssigkeit stromauf der Aufteilung in den ersten Teilstrom und den zweiten Teilstrom in einer Unterkühleinheit unterkühlt wird.
  5. Einrichtung zum Trennen von Luft zum Erzeugen eines Stickstoffprodukts, die umfaßt:
    Hauptwärmetauschmittel (32) zum Kühlen der Luft auf eine für ihre Rektifizierung geeignete Temperatur,
    eine Destillationssäule (30), die zum Rektifizieren eines ersten Teils der gekühlten Luft in eine sauerstoffreiche Flüssigkeitsfraktion am Boden und eine stickstoffreiche Dampffraktion im Kopf ausgebildet ist,
    einen Kopfkondensator (42), der mit der Destillationssäule (30) in Verbindung steht, um einen Teil der stickstoffreichen Dampffraktion zum Erzeugen eines Rückflusses für die Destillationssäule (30) zu kondensieren,
    Verdampfungsmittel (54) zum teilweisen Verdampfen eines Stroms der Sauerstoff-angereicherten Flüssigkeitsfraktion, wobei die Verdampfungsmittel (54) so angeordnet sind, daß ein zweiter Teil der gekühlten Luft kondensiert wird, und wobei die Verdampfungsmittel (54) einen Auslaß für kondensierte Luft in Verbindung mit einem Zwischenbereich der Destillationssäule (30) aufweist,
    einen Phasentrenner (56), der mit den Verdampfungsmitteln (54) in Verbindung steht, zum Trennen des teilweise verdampften Sauerstoff-angereicherten Flüssigkeitsstroms in eine Flüssigkeitsphase und eine Dampfphase,
    wobei der Phasentrenner (56) einen Auslaß für Flüssigkeit in Verbindung mit dem Kopfkondensator (42) über ein ersten Druckminderventil (60) aufweist,
    ein zweites Expansionsventil (55) stromauf der Verdampfungsmittel (54) zum Expandieren des Stroms der Sauerstoff-angereicherten Flüssigkeit, die teilweise zu verdampfen ist,
    Expansionsmittel (64) zum Expandieren eines Stroms der Dampfphase unter Arbeitsleistung, wobei die Expansionsmittel mit einem Auslaß für Dampf vom Phasentrenner (56) in Verbindung stehen, und
    einen Auslaß der Destillationssäule (30) für einen Produktstrom eines verbleibenden Teils der genannten stickstoffreichen Kopfdampffraktion,
    wobei die Verdampfungsmittel (54) außerdem Kanäle zum Kondensieren eines Stroms aus Dampf mit geringerem Sauerstoffgehalt als Luft aus einem gewählten Zwischenbereich der Destillationssäule (30) aufweisen, die mit ihren Auslaßenden mit einem weiteren Zwischenbereich der Destillationssäule (30) oberhalb des gewählten Zwischenbereichs in Verbindung stehen.
  6. Einrichtung zum Trennen von Luft zum Erzeugen eines Stickstoffprodukts, die umfaßt:
    Hauptwärmetauschmittel (32) zum Kühlen der Luft auf eine für ihre Rektifizierung geeignete Temperatur,
    eine Destillationssäule (30), die für das Rektifizieren eines ersten Teils der gekühlten Luft in eine sauerstoffreiche Flüssigkeitsfraktion am Boden und eine stickstoffreiche Dampffraktion im Kopf ausgebildet ist,
    einen Kopfkondensator (42), der mit der Destillationssäule (30) in Verbindung steht, zum Kondensieren eines Teils des stickstoffreichen Dampfs im Kopf zum Erzeugen eines Rückflusses für die Destillationssäule,
    einen Auslaß der Destillationssäule (30) für einen Strom der sauerstoffreichen Flüssigkeitsfraktion am Boden,
    ein Druckminderventil (60), das mit dem Auslaß der Destillationssäule (30) in Verbindung steht, um einen ersten Teil des Stroms der sauerstoffreichen Bodenflüssigkeitsfraktion zu expandieren, wobei das Druckminderventil (60) einen mit dem Kopfkondensator in Verbindung stehenden Auslaß aufweist,
    Verdampfungsmittel (54) zum Verdampfen eines zweiten Teils des Stroms der sauerstoffreichen Bodenflüssigkeit, wobei die Verdampfungsmittel (54) für das Kondensieren eines zweiten Teils der gekühlten Luft ausgelegt sind und einen Auslaß für kondensierte Luft in Verbindung mit einem Zwischenbereich der Destillationssäule (30) haben,
    ein Expansionsventil (55) stromauf der Verdampfungsmittel (54) zum Expandieren des zweiten Teils des Stroms der sauerstoffreichen Bodenflüssigkeit,
    Expansionsmittel (64) zum Expandieren des verdampften zweiten Teils der sauerstoffreichen Bodenflüssigkeitsfraktions und der Arbeitsleistung zum Erzeugen von Kühlleistung, und
    einen Auslaß der Destillationssäule (30) für einen Produktstrom eines verbleibenden Teils der stickstoffreichen Kopfdampffraktion,
    wobei die Verdampfungsmittel (54) außerdem Kanäle zum Kondensieren eines Stroms aufdampft mit geringerem Sauerstoffgehalt als Luft aus einem gewählten Zwischenbereich der Destillationssäule (30) aufweisen, wobei die Kanäle mit ihren Auslaßenden mit einem weiteren Zwischenbereich der Destillationssäule (30) oberhalb des gewählten Zwischenbereichs in Verbindung stehen.
EP95307528A 1994-10-25 1995-10-24 Lufttrennungsverfahren und Vorrichtung zur Herstellung von Stickstoff Expired - Lifetime EP0709632B1 (de)

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US459946 1983-01-21
US32903594A 1994-10-25 1994-10-25
US329035 1994-10-25
US37406095A 1995-01-19 1995-01-19
US08/459,946 US5507148A (en) 1994-10-25 1995-05-31 Air separation method and apparatus to produce nitrogen
US374060 1999-08-13

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EP0709632A3 EP0709632A3 (de) 1996-09-11
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GB974639A (en) * 1962-05-29 1964-11-11 British Oxygen Co Ltd Separation of air
US5170630A (en) * 1991-06-24 1992-12-15 The Boc Group, Inc. Process and apparatus for producing nitrogen of ultra-high purity
US5163296A (en) * 1991-10-10 1992-11-17 Praxair Technology, Inc. Cryogenic rectification system with improved oxygen recovery
JPH05187767A (ja) * 1992-01-14 1993-07-27 Teisan Kk 超高純度窒素製造方法及びその装置
US5396772A (en) * 1994-03-11 1995-03-14 The Boc Group, Inc. Atmospheric gas separation method

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CA2159308A1 (en) 1996-04-26
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TR199501297A2 (tr) 1996-06-21
DE69520922T2 (de) 2001-12-06
IL115348A (en) 1999-11-30
KR0168707B1 (ko) 1999-01-15
IL115348A0 (en) 1995-12-31
AU700591B2 (en) 1999-01-07
EP0709632A2 (de) 1996-05-01
AU3433995A (en) 1996-05-09
DE69520922D1 (de) 2001-06-21
KR960013416A (ko) 1996-05-22

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