EP1482266B1 - Process and device for the recovery of Krypton and/or Xenon by cryogenic separation of air - Google Patents

Process and device for the recovery of Krypton and/or Xenon by cryogenic separation of air Download PDF

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Publication number
EP1482266B1
EP1482266B1 EP20040011942 EP04011942A EP1482266B1 EP 1482266 B1 EP1482266 B1 EP 1482266B1 EP 20040011942 EP20040011942 EP 20040011942 EP 04011942 A EP04011942 A EP 04011942A EP 1482266 B1 EP1482266 B1 EP 1482266B1
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EP
European Patent Office
Prior art keywords
krypton
xenon
column
crude argon
liquid
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.)
Not-in-force
Application number
EP20040011942
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German (de)
French (fr)
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EP1482266A1 (en
Inventor
Christian Kunz
Dietrich Rottmann
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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Publication date
Priority to DE2003134560 priority Critical patent/DE10334560A1/en
Application filed by Linde GmbH filed Critical Linde GmbH
Priority to EP20040011942 priority patent/EP1482266B1/en
Publication of EP1482266A1 publication Critical patent/EP1482266A1/en
Application granted granted Critical
Publication of EP1482266B1 publication Critical patent/EP1482266B1/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
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04872—Vertical layout of cold equipments within in the cold box, e.g. columns, heat exchangers etc.
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04084—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
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    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
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    • F25J3/0429—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 feed air, e.g. used as waste or product air or expanded into an auxiliary column
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    • 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
    • F25J3/04642—Recovering noble gases from 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
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    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04642—Recovering noble gases from air
    • F25J3/04648—Recovering noble gases from air argon
    • F25J3/04654—Producing crude argon in a crude argon column
    • F25J3/04666—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system
    • F25J3/04672—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser
    • F25J3/04678—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser cooled by oxygen enriched liquid from high pressure column bottoms
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    • 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
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    • F25J3/0469—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser and an intermediate re-boiler/condenser
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    • 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
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    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04642—Recovering noble gases from air
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    • F25J3/04654—Producing crude argon in a crude argon column
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    • F25J3/04703—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser being arranged in more than one vessel
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    • 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
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    • F25J3/04721—Producing pure argon, e.g. recovered from a crude argon column
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    • F25J3/04642—Recovering noble gases from air
    • F25J3/04745—Krypton and/or Xenon
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    • F25J2235/58—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being argon or crude argon
    • 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
    • F25J2240/46—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
    • 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
    • F25J2245/50—Processes or apparatus involving steps for recycling of process streams the recycled stream being 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/58—Processes or apparatus involving steps for recycling of process streams the recycled stream being argon or crude argon
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/02—Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/04—Down-flowing type boiler-condenser, i.e. with evaporation of a falling liquid film
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/10—Boiler-condenser with superposed stages
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/20—Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams

Definitions

  • the invention relates to a method for obtaining krypton and / or xenon by cryogenic separation of air according to the preamble of patent claim 1.
  • the high pressure column is operated at a higher pressure than the low pressure column; the two columns are preferably in heat exchange relationship with one another, for example via a main condenser, in which head gas of the high-pressure column is liquefied against vaporizing bottom liquid of the low-pressure column.
  • the rectification system of the invention may be designed as a classical double column system, but also as a three-column or multi-column system.
  • other devices may be present to recover other air components, particularly noble gases, such as argon recovery.
  • a process for the recovery of krypton and / or xenon by cryogenic separation of air and a corresponding device are out DE 10000017 A1 known.
  • a krypton- and xenon-containing fraction namely the bottom liquid, out of the high-pressure column of the double column for nitrogen-oxygen separation without concentration-changing measures in another column, which is used for krypton-xenon recovery.
  • the invention has for its object to further improve the krypton and xenon recovery and in particular to perform particularly economical manner.
  • This object is achieved in that the second feed air stream is introduced downstream of its work-relaxation in the krypton-xenon enrichment column.
  • the krypton and xenon contained in the work-performing relaxed air can be channeled into the krypton-xenon concentrate. It results in a particularly high yield of krypton and / or xenon.
  • the investment requirement is relatively low, because no additional column for the washing out of krypton and xenon from the work-performing relaxed air is needed, as in EP 1308680 A1 (local FIG. 4 ) is the case, but this air is introduced directly into the already existing krypton-xenon enrichment column, which preferably has a bottom evaporator.
  • the feed point of the air is preferably in the lower part of the krypton-xenon enrichment column, for example immediately above the sump or one to five. preferably one to three floors above.
  • the krypton-xenon enrichment column also serves to wash out krypton and xenon from the feed air, which has been work-relaxed.
  • ascending vapor for the krypton-xenon column can be most conveniently formed by operating the bottom vaporizer of the krypton-xenon enrichment column with an argon-enriched vapor from an intermediate zone of crude argon rectification ,
  • the conversion in the argon-rich part of the crude argon rectification is reduced without the argon yield being significantly reduced.
  • the crude argon column can be made correspondingly slimmer and therefore cheaper in this area.
  • the crude argon rectification is divided into two or more crude argon columns.
  • the argon-enriched vapor may be formed by a portion of the top vapor of the first to (n-1) th crude argon column.
  • part of the top vapor of the first crude argon column connected to the low-pressure column is conducted into the evaporation space of the bottom evaporator of the krypton-xenon enrichment column where it is at least partially condensed.
  • the condensate flows back into the first crude argon column and does not need to be introduced into the second crude argon column from which the crude argon product is taken in this case. Accordingly, the conversion in the second crude argon column decreases. This can be carried out correspondingly cheaper.
  • At least part of the top vapor of the crude argon rectification or the top vapor of the n-th crude argon column is introduced into the liquefaction space of a crude argon top condenser and at least partially liquefied there by indirect heat exchange with a fraction evaporating in the evaporation space of the crude argon top condenser.
  • a purge solution can be withdrawn from the evaporation space of the crude argon overhead condenser and fed as a krypton and xenon-containing fraction to the krypton-xenon enrichment column.
  • At least a portion of the vapor formed in the evaporation space of the crude argon overhead condenser may be introduced into the krypton-xenon enrichment column.
  • the invention also relates to a device for obtaining krypton and / or xenon by cryogenic separation of air according to claims 7 and 8.
  • AIR compressed air
  • the main heat exchanger has three parallel blocks 105a, 105b, 105c in the exemplary embodiment.
  • the first air stream 102 is cooled in all three blocks 105a, 105b, 105c of the main heat exchanger to about dew point and introduced without further pressure-changing measures via line 1 in gaseous form in the high pressure column 2 of a rectification system for nitrogen-oxygen separation.
  • the rectification system for nitrogen-oxygen separation also has a low-pressure column 3 and a main condenser 4, which in the example is designed as a combined falling-film and bath evaporator.
  • Gaseous nitrogen 6 from the head of the high-pressure column is fed to the condensation space of the main condenser 4.
  • the condensate 7 formed there is introduced into the high-pressure column and used there as reflux.
  • Some theoretical plates deeper liquid nitrogen 106 is removed from the high pressure column 2 and branched at 107.
  • a first branch stream of liquid nitrogen is recovered via line 114 as a liquid nitrogen product (LIN).
  • Another branch stream 111 of the liquid nitrogen from the high-pressure column 2 is brought to a desired product pressure in a liquid state pump 112, vaporized in the main heat exchanger block 105a (pseudo-vaporized in the case of supercritical pressure) and warmed to about ambient temperature and via line 113 discharged as gaseous pressure product (PGAN).
  • the third air stream 104 which has been brought to a correspondingly high pressure in a secondary compressor 115 with aftercooler 116, serves to vaporize the nitrogen which has been brought to liquid pressure.
  • the liquefied or supercritical cold high-pressure air 117 which is liquefied or supercritical within the scope of internal compression, is throttled into the high-pressure column 2 at least partly in liquid form, namely at a first intermediate point some theoretical plates above the high-pressure column sump. From a second intermediate point, which in turn is arranged a few theoretical plates above this first intermediate point, an oxygen-containing liquid 45 is withdrawn from the high-pressure column, which hardly has any more volatile components such as in particular krypton and xenon. The cooled in the subcooling countercurrent 10 liquid is fed via line 46 and throttle valve 47 in the low pressure column 3.
  • the oxygen-enriched bottoms liquid 13 of the high-pressure column 2 is likewise cooled in the subcooling countercurrent 10.
  • the supercooled oxygen-enriched liquid 14-15 is further cooled in a pure argon evaporator 63 and is finally introduced in part via lines 16 and 16a into the evaporation space of a crude argon top condenser 17 of crude argon rectification 18/19.
  • Another part 16b of the supercooled oxygen-containing liquid 16 is fed into the evaporation space of a top condenser 21 of a pure argon column 22.
  • the crude argon top condenser 17 is designed as a circulation evaporator, that is, the evaporation space contains a liquid bath, in which a heat exchanger block is at least partially, preferably completely immersed (not shown). Liquid is sucked in by the thermosiphon effect at the bottom of the evaporation passages. At its upper end, a mixture of vapor and undiluted liquid emerges, the latter flowing back into the liquid bath.
  • the oxygen-enriched Fraction 16a partially evaporated; For example, 0.5 to 10 mol%, preferably 1 to 5 mol% of the introduced liquid 16a are withdrawn liquid as rinsing liquid 26 from the evaporation space of the crude argon top condenser 17.
  • This partial evaporation increases the concentration of less volatile components, in particular krypton and xenon, in the liquid and reduces it in the vapor (in each case in comparison to the composition of fraction 16a).
  • the vapor generated in the partial evaporation is withdrawn as a gaseous stream 25 from the evaporation space of the crude argon top condenser 17. Remaining liquid is removed as "rinse liquid" 26 from the liquid bath and fed to the krypton-xenon enrichment column 24 immediately above the sump.
  • impure nitrogen 33 in gas form and oxygen 34 in liquid form are at least partially withdrawn as products or residual gas.
  • the gaseous impurity nitrogen 33 is heated in the supercooling countercurrent 10 and in the main heat exchanger 105a / 105c.
  • the liquid oxygen 34 is divided into two parts. A first part 35 is withdrawn as a liquid product (LOX), optionally after partial supercooling in the subcooling countercurrent 10 (not shown).
  • the second part 41 of the liquid oxygen 34 from the bottom of the low pressure column 3 is - similar to the liquid nitrogen 111 from the high pressure column - subjected to an internal compression (internal compression), brought in a pump 42 to the desired product pressure and via line 43 the main heat exchanger ( Block 105a) flows in, where it evaporates (or - at supercritical product pressure - pseudo-evaporated) and is warmed to about ambient temperature. Finally, it is recovered via line 120 as a gaseous oxygen pressure product. Evaporation and heating are carried out in indirect heat exchange with the high pressure air stream 104-117.
  • Another oxygen stream 93 is withdrawn directly in gaseous form from the low-pressure column 3, heated in the heat exchanger blocks 105a, 105b and finally withdrawn via line 94 as a non-pressurized gas product (GOX).
  • GOX non-pressurized gas product
  • an argon-containing fraction from the low-pressure column 3 is passed into a crude argon rectification, which in the example in two serially connected Rohargonkla 18 and 19 is performed (so-called split Rohargonklale).
  • the argon-containing fraction 48 is fed to the first crude argon column 18 directly above the bottom in gaseous form.
  • the rising vapor accumulates in argon.
  • the head gas 81 of the first crude argon column 18 flows to a first part via line 49 on to the bottom of the second crude argon column 19.
  • Another part 82 of the top gas 81 serves as heating means for the bottom evaporator 27 of the krypton-xenon Enrichment column 24 is introduced into the liquefaction space and condensed there.
  • the liquid 83 produced in the process is applied to the first crude argon column 18 as reflux liquid.
  • gaseous crude argon 50 is withdrawn, introduced into the liquefaction space of the crude argon top condenser 17 and condensed there to a large extent.
  • the liquid 51 produced in the process is applied to the second crude argon column 19 as reflux liquid.
  • Gaseous remaining crude argon 58 from the liquefaction space of the condenser-evaporator 17 is further decomposed in the pure argon column 22, in particular freed of more volatile components such as nitrogen.
  • Pure argon product (LAR) is withdrawn via lines 59 and 60 in liquid form.
  • Another portion 61 of the bottom liquid of the pure argon column 22 is vaporized in the above-mentioned pure argon evaporator 63 with attached separator 62 and returned via line 64 as ascending steam in the pure argon column 22.
  • the top condenser 21 of the pure argon column is cooled as already described by a supercooled liquid 16b. From the evaporation space of the top condenser 21, vapor 66 and remaining liquid 65 are withdrawn. The vapor 66 is fed into the low-pressure column 3 at a suitable intermediate point. The virtually krypton and xenon-free liquid 65 is applied to the krypton-xenon enrichment column 24. In the liquefaction space of the top condenser 21, top gas 67 of the pure argon column 22 condenses partially. there generated reflux liquid 68 is applied to the pure argon column. Residual vapor 69 is blown off into the atmosphere.
  • the second air stream 103 is further compressed in a turbine-driven after-compressor 85 with aftercooler 86, cooled in the main heat exchanger block 105 a to an intermediate temperature and expanded in an air turbine 87 to perform work.
  • the expanded air 88 is injected via line 88 into the krypton-xenon enrichment column 24.
  • At least a portion of the oxygen-containing - but substantially krypton- and xenon-free - liquid 45/46 from the high pressure column 2 could be used as reflux liquid in the krypton-xenon enrichment column 24 - not shown in the drawing.
  • these components are washed into the sump, while methane can be partially discharged with the head gas 84.
  • the latter is fed in the embodiment of the low-pressure column 3 at a suitable intermediate point.
  • a krypton-xenon concentrate 30 is withdrawn in liquid form (crude Kr / Xe) containing, for example, a krypton content of about 2400 ppm and a xenon content of about 200 ppm:
  • the concentrate 30 mainly consists of oxygen and, for example, still contains about 10 to 40 mol% of nitrogen and hydrocarbons.
  • the concentrate 30 may be stored in a liquid tank or directly fed to further processing to obtain pure krypton and / or xenon.
  • Balancing streams 96, 97 are provided between blocks 105a, 105b, 105c of the main heat exchanger system.
  • FIG. 1 also shows an additional column 89 for obtaining a helium-neon concentrate 90, 91 (crude HeNe) from uncondensed nitrogen vapor 92 withdrawn from the main condenser 4.
  • This helium-neon recovery is fundamentally independent of the krypton-xenon recovery according to the invention.
  • AIR compressed air
  • the main heat exchanger has two parallel blocks 105a, 105b in the exemplary embodiment.
  • the first air stream 102 is cooled in both blocks 105a and 105b of the main heat exchanger to about dew point and introduced without further pressure-changing measures via line 1 in gaseous form in the high pressure column 2 of a rectification system for nitrogen-oxygen separation.
  • the rectification system for nitrogen-oxygen separation also has a low pressure column 3 and a main condenser 4, which is formed in the example as a falling film evaporator.
  • Gaseous nitrogen 6 from the head of the high-pressure column is fed to the condensation space of the main condenser 4.
  • the condensate 7 formed there is introduced into the high-pressure column and used there as part of the return.
  • Another part 106 is removed liquid from the high-pressure column 2 and branches again at 107.
  • a first branch stream of liquid nitrogen is subcooled in a subcooler countercurrent 10, introduced via line 108 into a separator (phase separator) 109, and finally recovered via line 114 as a liquid nitrogen product (LIN).
  • Another branch stream 111 of the liquid nitrogen from the top of the high-pressure column 2 (or main condenser 4) is brought to a desired product pressure in a liquid state pump 112, vaporized in the main heat exchanger block 105a (or pseudo-vaporized in the case of supercritical pressure) and warmed to about ambient temperature and discharged via line 113 as gaseous pressure product (PGAN).
  • the third air stream 104 which has been brought to a correspondingly high pressure in a secondary compressor 115 with aftercooler 116, serves to vaporize the nitrogen which has been brought to liquid pressure.
  • impure liquid nitrogen is taken from some theoretical plates below the top of the high pressure column 2, in the subcooling countercurrent 10 subcooled and fed via line 11 and throttle valve 12 of the low pressure column 3 at the top.
  • the cold high-pressure air 117 liquefied or supercritical within the scope of internal compression is at least partly throttled into the high-pressure column 2 via valve 118 and line 44, namely at a "first intermediate point” some theoretical plates above the high-pressure column sump.
  • a "second intermediate point” which in turn is arranged some theoretical plates above this first intermediate point, an oxygen-containing liquid 45 is withdrawn from the high-pressure column, which hardly has any more volatile components such as in particular krypton and xenon.
  • the cooled in the subcooling countercurrent 10 liquid 119 is partially fed via line 46 and throttle valve 47 in the low pressure column 3.
  • Another part 20 of the supercooled oxygen-containing liquid 119 is fed into the evaporation space of a top condenser 21 of a pure argon column 22.
  • the oxygen-enriched bottoms liquid 13 of the high-pressure column 2 is likewise cooled in the subcooling countercurrent 10.
  • the supercooled oxygen-enriched liquid 14-15 is further cooled in a pure argon evaporator 63 and is finally introduced via line 16 into the vaporization space of a crude argon top condenser 17, which is the top condenser of crude argon rectification 18/19.
  • the crude argon top condenser 17 is designed as a circulation evaporator, that is, the evaporation chamber contains a liquid bath, in which a heat exchanger block is at least partially, preferably completely immersed (in deviation from the schematic representation in the drawing). Liquid is sucked in by the thermosiphon effect at the bottom of the evaporation passages. At its upper end, a mixture of vapor and undiluted liquid emerges, the latter flowing back into the liquid bath.
  • the oxygen-enriched fraction 16 is partially evaporated; For example, 0.5 to 10 mol%, preferably 1 to 5 mol% of the introduced liquid 16 are withdrawn liquid as rinsing liquid 26 from the evaporation space of the crude argon top condenser 17. Due to this partial evaporation, the concentration of less volatile components, in particular of krypton and xenon, in the Increased liquid and reduced in the vapor (in each case compared to the composition of the oxygen-enriched fraction 16). The vapor generated in the partial evaporation is withdrawn as a gaseous stream 25 from the evaporation space of the crude argon top condenser 17. Remaining liquid is removed as "rinse liquid" 26 from the liquid bath and fed to the krypton-xenon enrichment column 24 immediately above the sump.
  • impure nitrogen 33 in gas form and oxygen 34 in liquid form are at least partially withdrawn as products or residual gas.
  • the gaseous impure nitrogen 33 is heated together with flash gas 110 from the separator 109 in the subcooling countercurrent 10 and in the main heat exchanger 105a / 105b.
  • the liquid oxygen 34 is divided into a total of three parts. A first and a second part are initially conveyed together via line 35 and pump 36. The first part 37 flows to the evaporation space of the main capacitor 4 and is partially evaporated there. The resulting vapor-liquid mixture 38 flows back to the bottom of the low-pressure column 3. Via the lines 39 and 40, the second part is withdrawn as a liquid product (LOX), after partial supercooling in the subcooling countercurrent 10th
  • the third part 41 of the liquid oxygen 34 from the bottom of the low pressure column 3 is - similar to the liquid nitrogen 111 from the high pressure column - subjected to an internal compression (internal compression), brought in a pump 42 to the desired product pressure and via line 43 the main heat exchanger ( Block 105a) flows in, where it evaporates (or - at supercritical product pressure - pseudo-evaporated) and is warmed to about ambient temperature. Finally, it is recovered via line 120 as a gaseous oxygen pressure product. Evaporation and heating are carried out in indirect heat exchange with the high pressure air stream 104-117.
  • an argon-containing fraction from the low-pressure column 3 is passed into a crude argon rectification, which in the example is carried out in two serially connected crude argon columns 18 and 19 (so-called split crude argon column).
  • the argon-containing fraction 48 is fed to the first crude argon column 18 directly above the bottom in gaseous form.
  • the rising steam enriches to argon.
  • the top gas of the first crude argon column 18 continues to flow via line 49 to the bottom of the second crude argon column 19.
  • Gaseous remaining crude argon 58 from the liquefaction of the crude argon top condenser 17 is further decomposed in the pure argon column 22, in particular freed of more volatile constituents such as nitrogen.
  • Pure argon product (LAR) is withdrawn via lines 59 and 60 in liquid form.
  • Another portion 61 of the bottom liquid of the pure argon column 22 is vaporized in the above-mentioned pure argon evaporator 63 with attached separator 62 and returned via line 64 as ascending steam in the pure argon column 22.
  • the top condenser 21 of the pure argon column is cooled by a supercooled liquid 20 as already described. From the evaporation space of the top condenser 21, vapor 66 and remaining liquid 65 are withdrawn. The vapor 66 is fed into the low-pressure column 3 at a suitable intermediate point. The virtually krypton and xenon-free liquid 65 is applied to the krypton-xenon enrichment column 24. In the liquefaction space of the top condenser 21, top gas 67 of the pure argon column 22 condenses partially. This generated return fluid 68 is applied to the pure argon column. Residual vapor 69 is blown off into the atmosphere.
  • the second air stream 103 is further compressed in a turbine-driven booster 85 with aftercooler 86, cooled in the main heat exchanger block 105 a to an intermediate temperature and expanded in an air turbine 87 to perform work.
  • the expanded air 88 is injected via line 88 into the krypton-xenon enrichment column 24.
  • a krypton-xenon concentrate 30 in liquid form is withdrawn (crude KrXe) containing, for example, a krypton content of about 2400 ppm and a xenon content of about 200 ppm:
  • the concentrate 30 consists mainly of oxygen and still contains about 10 mol% of nitrogen and hydrocarbons.
  • the concentrate 30 may be stored in a liquid tank or directly fed to further processing to obtain pure krypton and / or xenon.
  • FIG. 3 does not differ with respect to the sequence of process steps FIG. 2 , However, the arrangement of the krypton-xenon enrichment column 24 is different. While in FIG. 2 is mounted as a separate container above the first Rohargoncicle 18, it is located in FIG. 3 Krypton-xenon enrichment column 24 and second crude argon column 19 thus form, so to speak, a double column with the second condenser-evaporator as a "main condenser" between the crude argon head condenser 17 and the mass transfer region of the second crude argon column. Since the krypton-xenon enrichment column and the Rohargonkla 18, 19 have a similar diameter, such an arrangement can be particularly favorable apparatus.
  • the krypton-xenon enrichment column 24, the second crude argon column 19 and the pure argon column 22 and their condensers 27, 17, 21 are arranged such that the liquids 26, 51, 65, 68 and 123 flow towards their destination solely on the basis of the geodetic gradient.
  • this arrangement is not always optimal for space reasons.
  • the pure argon column 22 is arranged lower than in FIG. 2 so that the liquid 65 must flow upwards.
  • the evaporation space of the top condenser 21 of the pure argon column 22 is under slightly higher pressure than in FIG. 2 operated, so that the rinsing liquid 65 is pressed due to the corresponding pressure gradient in the krypton-xenon enrichment column. A corresponding pressure difference is maintained in the gas line 66 through the control flap 294.
  • the pure argon column of FIG. 5 is also lower than in FIG. 2 , However, no increased pressure in the evaporation space of the top condenser 21 is required here since the flushing liquid 465 is introduced from the top condenser 21 of the pure argon column 22 directly into the low pressure column 3 at an intermediate point 492 which is lower than the condenser 21.
  • the feed liquid 493 for the krypton-xenon enrichment column is branched off here already upstream of the top condenser 21 from the liquid 20, which was withdrawn via the lines 45 and 119 from the second intermediate point of the high-pressure column 2. Another part of this liquid 20 flows into the evaporation space of the top condenser 21 of the pure argon column 22.
  • the fluid to be evaporated flows from top to bottom through the evaporation space and is partially evaporated.
  • a “circulation evaporator” also called liquid bath evaporator
  • the heat exchanger block is in a liquid bath of the fluid to be evaporated. This flows by means of the thermosiphon effect from bottom to top through the evaporation passages and exits the top again as a two-phase mixture. The remaining liquid flows outside the heat exchanger block back into the liquid bath.
  • the evaporation space may include both the evaporation passages and the outside space around the heat exchanger block.

Description

Die Erfindung betrifft ein Verfahren zur Gewinnung von Krypton und/oder Xenon durch Tieftemperaturzerlegung von Luft gemäß dem Oberbegriff des Patentanspruchs 1.The invention relates to a method for obtaining krypton and / or xenon by cryogenic separation of air according to the preamble of patent claim 1.

Ein solches Verfahren ist aus der Druckschrift EP 1308680 A1 bekanntSuch a method is known from the document EP 1308680 A1 known

Die Grundlagen der Tieftemperaturzerlegung von Luft im Allgemeinen sowie der Aufbau von Rektifiziersystemen zur Stickstoff-Sauerstoff-Trennung im Speziellen sind in der Monografie "Tieftemperaturtechnik" von Hausen/Linde (2. Auflage, 1985) und in einem Aufsatz von Latimer in Chemical Engineering Progress (Vol. 63, No.2, 1967, Seite 35 ) beschrieben. Bei Zwei-Säulen-Systemen wird die Hochdrucksäule unter einem höheren Druck als die Niederdrucksäule betrieben; die beiden Säulen stehen vorzugsweise in Wärmeaustauschbeziehung zueinander, beispielsweise über einen Hauptkondensator, in dem Kopfgas der Hochdrucksäule gegen verdampfende Sumpfflüssigkeit der Niederdrucksäule verflüssigt wird. Das Rektifiziersystem der Erfindung kann als klassisches Doppelsäulensystem ausgebildet sein, aber auch als Drei- oder Mehrsäulensystem. Zusätzlich zu den Kolonnen zur Stickstoff-Sauerstoff-Trennung können weitere Vorrichtungen zur Gewinnung anderer Luftkomponenten, insbesondere von Edelgasen vorhanden sein, beispielsweise eine Argongewinnung.The basics of low-temperature decomposition of air in general and the construction of rectification systems for nitrogen-oxygen separation in particular are described in the monograph "cryogenic technology" by Hausen / Linde (2nd edition, 1985) and in an article by Latimer in Chemical Engineering Progress (Vol. 63, No.2, 1967, page 35 ). In two-column systems, the high pressure column is operated at a higher pressure than the low pressure column; the two columns are preferably in heat exchange relationship with one another, for example via a main condenser, in which head gas of the high-pressure column is liquefied against vaporizing bottom liquid of the low-pressure column. The rectification system of the invention may be designed as a classical double column system, but also as a three-column or multi-column system. In addition to the nitrogen-oxygen separation columns, other devices may be present to recover other air components, particularly noble gases, such as argon recovery.

Ein Verfahren zur Gewinnung von Krypton und/oder Xenon durch Tieftemperaturzerlegung von Luft und eine entsprechende Vorrichtung sind aus DE 10000017 A1 bekannt. Hier wird eine krypton- und xenonhaltige Fraktion, nämlich die Sumpfflüssigkeit, aus der Hochdrucksäule der Doppelsäule zur Stickstoff-Sauerstoff-Trennung ohne konzentrationsverändernde Maßnahmen in eine weitere Säule geführt, die zur Krypton-Xenon-Gewinnung dient. Weitere einschlägige Verfahren sind in DE 2055099 (= US 3751934 ), H. Springmann, Linde-Berichte aus Technik und Wissenschaft, 39/1976, S. 48-54 , oder DE 2605305 A offenbart.A process for the recovery of krypton and / or xenon by cryogenic separation of air and a corresponding device are out DE 10000017 A1 known. Here, a krypton- and xenon-containing fraction, namely the bottom liquid, out of the high-pressure column of the double column for nitrogen-oxygen separation without concentration-changing measures in another column, which is used for krypton-xenon recovery. Further relevant procedures are in DE 2055099 (= US 3751934 ) H. Springmann, Linde reports from technology and science, 39/1976, P. 48-54 , or DE 2605305 A disclosed.

Prozesse der eingangs genannten Art sind in EP 96610 A und Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A17, 1991, Seite 507 beschrieben. Kälte für den Augleich von Austauschverlusten und gegebenenfalls für die Produktverflüssigung wird hier durch arbeitsleistende Entspannung eines Einsatzluftstroms erzeugt. Die arbeitsleistend entspannte Luft wird in die Niederdrucksäule eingeleitet, ebenso wie bei dem in EP 1376037 A1 beschriebenen Verfahren.Processes of the type mentioned are in EP 96610 A and Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A17, 1991, page 507. Cold for the same exchange losses and, where appropriate, for the product liquefaction Here produced by work-performing relaxation of a feed air flow. The work-relaxing air is introduced into the low-pressure column, as well as in the EP 1376037 A1 described method.

Der Erfindung liegt die Aufgabe zugrunde, die Krypton- und Xenon-Gewinnung weiter zu verbessern und insbesondere auf besonders wirtschaftliche Weise durchzuführen.The invention has for its object to further improve the krypton and xenon recovery and in particular to perform particularly economical manner.

Diese Aufgabe wird dadurch gelöst, dass der zweite Einsatzluftstrom stromabwärts seiner arbeitsleistenden Entspannung in die Krypton-Xenon-Anreicherungssäule eingeleitet wird.This object is achieved in that the second feed air stream is introduced downstream of its work-relaxation in the krypton-xenon enrichment column.

Auf diese Weise kann auch das in der arbeitsleistend entspannten Luft enthaltene Krypton und Xenon in das Krypton-Xenon-Konzentrat geschleust werden. Er ergibt sich eine besonders hohe Ausbeute an Krypton und/oder Xenon. Dabei ist der Investitionsbedarf relativ gering, weil keine zusätzliche Säule für das Auswaschen von Krypton und Xenon aus der arbeitsleistend entspannten Luft benötigt wird, wie es bei EP 1308680 A1 (dortige Figur 4) der Fall ist, sondern diese Luft direkt in die ohnehin vorhandene Krypton-Xenon-Anreicherungssäule eingeleitet wird, die vorzugsweise einen Sumpfverdampfer aufweist. Die Einspeisestelle der Luft liegt vorzugsweise im unteren Bereich der Krypton-Xenon-Anreicherungssäule, zum Beispiel unmittelbar oberhalb des Sumpfs oder ein bis fünf. vorzugsweise ein bis drei Böden darüber. Neben ihrer üblichen Funktion dient die Krypton-Xenon-Anreicherungssäule zusätzlich zum Auswaschen von Krypton und Xenon aus der Einsatzluft, die arbeitsleistend entspannt wurde.In this way, the krypton and xenon contained in the work-performing relaxed air can be channeled into the krypton-xenon concentrate. It results in a particularly high yield of krypton and / or xenon. The investment requirement is relatively low, because no additional column for the washing out of krypton and xenon from the work-performing relaxed air is needed, as in EP 1308680 A1 (local FIG. 4 ) is the case, but this air is introduced directly into the already existing krypton-xenon enrichment column, which preferably has a bottom evaporator. The feed point of the air is preferably in the lower part of the krypton-xenon enrichment column, for example immediately above the sump or one to five. preferably one to three floors above. In addition to its usual function, the krypton-xenon enrichment column also serves to wash out krypton and xenon from the feed air, which has been work-relaxed.

Wenn bei dem erfindungsgemäßen Verfahren außerdem eine Rohargonrektifikation zur Argongewinnung vorgesehen ist, kann auf besonders günstige Weise aufsteigender Dampf für die Krypton-Xenon-Säule gebildet werden, indem der Sumpfverdampfer der Krypton-Xenon-Anreicherungssäule mit einem argonangereicherten Dampf aus einem Zwischenbereich der Rohargonrektifikation betrieben wird. Dabei wird außerdem der Umsatz im argonreicheren Teil der Rohargonrektifikation vermindert, ohne dass die Argonausbeute nennenswert verringert würde. Die Rohargonsäule kann in diesem Bereich entsprechend schlanker und damit kostengünstiger ausgeführt werden.In addition, in the process of the present invention, when a crude argon argon recovery argon recovery is employed, ascending vapor for the krypton-xenon column can be most conveniently formed by operating the bottom vaporizer of the krypton-xenon enrichment column with an argon-enriched vapor from an intermediate zone of crude argon rectification , In addition, the conversion in the argon-rich part of the crude argon rectification is reduced without the argon yield being significantly reduced. The crude argon column can be made correspondingly slimmer and therefore cheaper in this area.

Dieser Vorteil kann besonders effizient ausgenutzt werden, falls die Rohargonrektifikation in zwei oder mehr Rohargonsäulen unterteilt ist. Wenn also die Rohargonrektifikation in einer Mehrzahl n (n ≥ 2) seriell verbundenen Rohargonsäulen durchgeführt wird, kann der argonangereicherte Dampf durch einen Teil des Kopfdampfs der ersten bis (n-1)-ten Rohargonsäule gebildet werden. Bei einer zweiteiligen Rohargonrektifikation wird also zum Beispiel ein Teil des Kopfdampfs der ersten, mit der Niederdrucksäule verbundenen Rohargonsäule in den Verdampfungsraum des Sumpfverdampfers der Krypton-Xenon-Anreicherungssäule geleitet und dort mindestens teilweise kondensiert. Das Kondensat strömt zurück in die erste Rohargonsäule und braucht nicht in die zweite Rohargonsäule, aus der in diesem Fall das Rohargonprodukt entnommen wird, eingeleitet zu werden. Entsprechend verringert sich der Umsatz in der zweiten Rohargonsäule. Diese kann entsprechend kostengünstiger ausgeführt werden.This advantage can be exploited particularly efficiently if the crude argon rectification is divided into two or more crude argon columns. Thus, when the crude argon rectification is performed in a plurality of n (n ≥ 2) serially connected crude argon columns, the argon-enriched vapor may be formed by a portion of the top vapor of the first to (n-1) th crude argon column. In a two-part crude argon rectification, for example, part of the top vapor of the first crude argon column connected to the low-pressure column is conducted into the evaporation space of the bottom evaporator of the krypton-xenon enrichment column where it is at least partially condensed. The condensate flows back into the first crude argon column and does not need to be introduced into the second crude argon column from which the crude argon product is taken in this case. Accordingly, the conversion in the second crude argon column decreases. This can be carried out correspondingly cheaper.

Zur Erzeugung von Rücklauf für die Rohargonrektifikation wird mindestens ein Teil des Kopfdampfs der Rohargonrektifikation beziehungsweise der Kopfdampf der n-ten Rohargonsäule in den Verflüssigungsraum eines Rohargon-Kopfkondensators eingeleitet und dort durch indirekten Wärmeaustausch mit einer im Verdampfungsraum des Rohargon-Kopfkondensators verdampfenden Fraktion mindestens teilweise verflüssigt.To generate reflux for the crude argon rectification, at least part of the top vapor of the crude argon rectification or the top vapor of the n-th crude argon column is introduced into the liquefaction space of a crude argon top condenser and at least partially liquefied there by indirect heat exchange with a fraction evaporating in the evaporation space of the crude argon top condenser.

Analog zu EP 1308680 A1 kann eine Spülflüssigkeit aus dem Verdampfungsraum des Rohargon-Kopfkondensators abgezogen und als krypton- und xenonhaltige Fraktion der Krypton-Xenon-Anreicherungssäule zugeleitet werden.Analogous to EP 1308680 A1 For example, a purge solution can be withdrawn from the evaporation space of the crude argon overhead condenser and fed as a krypton and xenon-containing fraction to the krypton-xenon enrichment column.

Außerdem kann mindestens ein Teil des in dem Verdampfungsraum des Rohargon-Kopfkondensators gebildeten Dampfes in die Krypton-Xenon-Anreicherungssäule eingeleitet werden.In addition, at least a portion of the vapor formed in the evaporation space of the crude argon overhead condenser may be introduced into the krypton-xenon enrichment column.

Die Erfindung betrifft außerdem eine Vorrichtung zur Gewinnung von Krypton und/oder Xenon durch Tieftemperaturzerlegung von Luft gemäß den Patentansprüchen 7 und 8.The invention also relates to a device for obtaining krypton and / or xenon by cryogenic separation of air according to claims 7 and 8.

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

Figur 1
ein erstes Ausführungsbeispiel der Erfindung mit Ausheizung der Krypton-Xenon-Anreicherungssäule mit einer Zwischenfraktion der Rohargonrektifikation,
Figur 2
ein weiteres Ausführungsbeispiel der Erfindung mit Ausheizung der Krypton-Xenon-Anreicherungssäule mit Kopfgas der Rohargonrektifikation,
Figur 3
ein Ausführungsbeispiel mit Integration von Krypton-Xenon-Anreicherungssäule und Rohargonsäule und
Figuren 4 und 5
weitere Anlagen mit abweichender Anordnung der Reinargonsäule.
The invention and further details of the invention are explained below with reference to embodiments schematically illustrated in the drawings. Hereby show:
FIG. 1
a first embodiment of the invention with heating of the krypton-xenon enrichment column with an intermediate fraction of crude argon rectification,
FIG. 2
a further embodiment of the invention with heating of the krypton-xenon enrichment column with overhead gas of the crude argon rectification,
FIG. 3
an embodiment with integration of krypton-xenon enrichment column and crude argon column and
FIGS. 4 and 5
other systems with a different arrangement of the pure argon column.

Über Leitung 101 von Figur 1 strömt komprimierte Luft (AIR) ein. Sie wird in einen ersten Luftstrom (Direktluft) 102, einen zweiten Luftstrom (Turbinenluft) 103 und einen dritten Luftstrom (Innenverdichtungsluft) 104 aufgeteilt. Der Hauptwärmetauscher weist in dem Ausführungsbeispiel drei parallele Blöcke 105a, 105b, 105c auf. Der erste Luftstrom 102 wird in allen drei Blöcken 105a, 105b, 105c des Hauptwärmetauschers auf etwa Taupunkt abgekühlt und ohne weitere druckverändernde Maßnahmen über Leitung 1 gasförmig in die Hochdrucksäule 2 eines Rektifiziersystems zur Stickstoff-Sauerstoff-Trennung eingeleitet. Das Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung weist außerdem eine Niederdrucksäule 3 und einen Hauptkondensator 4 auf, der in dem Beispiel als kombinierter Fallfilm- und Badverdampfer ausgebildet ist. Gasförmiger Stickstoff 6 vom Kopf der Hochdrucksäule wird dem Kondensationsraum des Hauptkondensators 4 zugeleitet. Das dort gebildete Kondensat 7 wird in die Hochdrucksäule eingeleitet und dort als Rücklauf verwendet. Einige theoretische Böden tiefer wird flüssiger Stickstoff 106 aus der Hochdrucksäule 2 entnommen und bei 107 verzweigt. Ein erster Zweigstrom flüssigen Stickstoffs wird über Leitung 114 als flüssiges Stickstoffprodukt (LIN) gewonnen. Ein anderer Zweigstrom 111 des flüssigen Stickstoffs aus der Hochdrucksäule 2 wird in einer Pumpe 112 in flüssigem Zustand auf einen gewünschten Produktdruck gebracht, im Hauptwärmetauscher-Block 105a verdampft (beziehungsweise im Falle eines überkritischen Drucks pseudo-verdampft) und auf etwa Umgebungstemperatur angewärmt und über Leitung 113 als gasförmiges Druckprodukt (PGAN) abgeführt. Zur Verdampfung des flüssig auf Druck gebrachten Stickstoffs dient der dritte Luftstrom 104, der in einem Nachverdichter 115 mit Nachkühler 116 auf einen entsprechend hohen Druck gebracht wurde.Via line 101 of FIG. 1 enters compressed air (AIR). It is divided into a first air flow (direct air) 102, a second air flow (turbine air) 103 and a third air flow (internal compression air) 104. The main heat exchanger has three parallel blocks 105a, 105b, 105c in the exemplary embodiment. The first air stream 102 is cooled in all three blocks 105a, 105b, 105c of the main heat exchanger to about dew point and introduced without further pressure-changing measures via line 1 in gaseous form in the high pressure column 2 of a rectification system for nitrogen-oxygen separation. The rectification system for nitrogen-oxygen separation also has a low-pressure column 3 and a main condenser 4, which in the example is designed as a combined falling-film and bath evaporator. Gaseous nitrogen 6 from the head of the high-pressure column is fed to the condensation space of the main condenser 4. The condensate 7 formed there is introduced into the high-pressure column and used there as reflux. Some theoretical plates deeper liquid nitrogen 106 is removed from the high pressure column 2 and branched at 107. A first branch stream of liquid nitrogen is recovered via line 114 as a liquid nitrogen product (LIN). Another branch stream 111 of the liquid nitrogen from the high-pressure column 2 is brought to a desired product pressure in a liquid state pump 112, vaporized in the main heat exchanger block 105a (pseudo-vaporized in the case of supercritical pressure) and warmed to about ambient temperature and via line 113 discharged as gaseous pressure product (PGAN). The third air stream 104, which has been brought to a correspondingly high pressure in a secondary compressor 115 with aftercooler 116, serves to vaporize the nitrogen which has been brought to liquid pressure.

Anstelle dieser Stickstoff-Innenverdichtung kann auch über Leitung 95 ein Druckstickstoff-Produkt direkt aus der Hochdrucksäule 2 entnommen werden.Instead of this nitrogen internal compression can be taken directly from the high-pressure column 2 via line 95, a pressure nitrogen product.

Über Leitung 9 wird unreiner flüssiger Stickstoff einige theoretische Böden unterhalb des Kopfs aus der Hochdrucksäule 2 entnommen, im Unterkühlungs-Gegenströmer 10 unterkühlt und über Leitung 11 und Drosselventil 12 der Niederdrucksäule 3 am Kopf zugeführt.Via line 9 impure liquid nitrogen is removed some theoretical plates below the head from the high pressure column 2, supercooled in the subcooling countercurrent 10 and fed via line 11 and throttle valve 12 of the low pressure column 3 at the top.

Die im Rahmen der Innenverdichtung verflüssigte oder überkritische kalte Hochdruckluft 117 wird über Ventil 118 und Leitung 44 mindestens zum Teil in flüssiger Form in die Hochdrucksäule 2 eingedrosselt, und zwar an einer ersten Zwischenstelle einige theoretischen Böden oberhalb des Hochdrucksäulen-Sumpfs. Von einer zweiten Zwischenstelle, die wiederum einige theoretische Böden oberhalb dieser ersten Zwischenstelle angeordnet ist, wird eine sauerstoffhaltige Flüssigkeit 45 aus der Hochdrucksäule abgezogen, die kaum noch schwererflüchtige Komponenten wie insbesondere Krypton und Xenon aufweist. Die im Unterkühlungs-Gegenströmer 10 abgekühlte Flüssigkeit wird über Leitung 46 und Drosselventil 47 in die Niederdrucksäule 3 eingespeist.The liquefied or supercritical cold high-pressure air 117, which is liquefied or supercritical within the scope of internal compression, is throttled into the high-pressure column 2 at least partly in liquid form, namely at a first intermediate point some theoretical plates above the high-pressure column sump. From a second intermediate point, which in turn is arranged a few theoretical plates above this first intermediate point, an oxygen-containing liquid 45 is withdrawn from the high-pressure column, which hardly has any more volatile components such as in particular krypton and xenon. The cooled in the subcooling countercurrent 10 liquid is fed via line 46 and throttle valve 47 in the low pressure column 3.

Die sauerstoffangereicherte Sumpfflüssigkeit 13 der Hochdrucksäule 2 wird ebenfalls im Unterkühlungs-Gegenströmer 10 abgekühlt. Die unterkühlte sauerstoffangereicherte Flüssigkeit 14 - 15 wird in einem Reinargon-Verdampfer 63 weiter abgekühlt und wird schließlich zu einem Teil über Leitung 16 und 16a in den Verdampfungsraum eines Rohargon-Kopfkondensators 17 einer Rohargonrektifikation 18/19 eingeleitet. Ein anderer Teil 16b der unterkühlten sauerstoffhaltigen Flüssigkeit 16 wird in den Verdampfungsraum eines Kopfkondensators 21 einer Reinargonsäule 22 eingespeist.The oxygen-enriched bottoms liquid 13 of the high-pressure column 2 is likewise cooled in the subcooling countercurrent 10. The supercooled oxygen-enriched liquid 14-15 is further cooled in a pure argon evaporator 63 and is finally introduced in part via lines 16 and 16a into the evaporation space of a crude argon top condenser 17 of crude argon rectification 18/19. Another part 16b of the supercooled oxygen-containing liquid 16 is fed into the evaporation space of a top condenser 21 of a pure argon column 22.

Der Rohargon-Kopfkondensator 17 ist als Umlaufverdampfer ausgebildet, das heißt der Verdampfungsraum enthält ein Flüssigkeitsbad, in das ein Wärmetauscherblock mindestens teilweise, vorzugsweise vollständig eingetaucht ist (nicht dargestellt). Flüssigkeit wird durch den Thermosiphon-Effekt am unteren Ende der Verdampfungspassagen angesaugt. An deren oberem Ende tritt ein Gemisch aus Dampf und unverdampfter Flüssigkeit aus, wobei letztere in das Flüssigkeitsbad zurückströmt. Im Rohargon-Kopfkondensator 17 wird die sauerstoffangereicherte Fraktion 16a partiell verdampft; beispielsweise 0,5 bis 10 mol-%, vorzugsweise 1 bis 5 mol-% der eingeführten Flüssigkeit 16a werden flüssig als Spülflüssigkeit 26 aus dem Verdampfungsraum des Rohargon-Kopfkondensators 17 abgezogen. Durch diese partielle Verdampfung wird die Konzentration von schwererflüchtigen Komponenten, insbesondere von Krypton und Xenon, in der Flüssigkeit erhöht und im Dampf vermindert (jeweils im Vergleich zur Zusammensetzung der Fraktion 16a). Der bei der partiellen Verdampfung erzeugte Dampf wird als gasförmiger Strom 25 aus dem Verdampfungsraum des Rohargon-Kopfkondensators 17 abgezogen. Verbleibende Flüssigkeit wird als "Spülflüssigkeit" 26 aus dem Flüssigkeitsbad abgeführt und der Krypton-Xenon-Anreicherungssäule 24 unmittelbar oberhalb des Sumpfs zugeleitet.The crude argon top condenser 17 is designed as a circulation evaporator, that is, the evaporation space contains a liquid bath, in which a heat exchanger block is at least partially, preferably completely immersed (not shown). Liquid is sucked in by the thermosiphon effect at the bottom of the evaporation passages. At its upper end, a mixture of vapor and undiluted liquid emerges, the latter flowing back into the liquid bath. In the crude argon top condenser 17, the oxygen-enriched Fraction 16a partially evaporated; For example, 0.5 to 10 mol%, preferably 1 to 5 mol% of the introduced liquid 16a are withdrawn liquid as rinsing liquid 26 from the evaporation space of the crude argon top condenser 17. This partial evaporation increases the concentration of less volatile components, in particular krypton and xenon, in the liquid and reduces it in the vapor (in each case in comparison to the composition of fraction 16a). The vapor generated in the partial evaporation is withdrawn as a gaseous stream 25 from the evaporation space of the crude argon top condenser 17. Remaining liquid is removed as "rinse liquid" 26 from the liquid bath and fed to the krypton-xenon enrichment column 24 immediately above the sump.

Von der Niederdrucksäule 3 werden Unreinstickstoff 33 in Gasform sowie Sauerstoff 34 in flüssiger Form mindestens teilweise als Produkte beziehungsweise Restgas abgezogen. Der gasförmige Unreinstickstoff 33 wird im Unterkühlungs-Gegenströmer 10 und im Hauptwärmetauscher 105a/105c angewärmt. Der flüssige Sauerstoff 34 wird in zwei Teile aufgeteilt. Ein erster Teil 35 wird als Flüssigprodukt (LOX) abgezogen, gegebenenfalls nach teilweiser Unterkühlung im Unterkühlungs-Gegenströmer 10 (nicht dargestellt).From the low-pressure column 3, impure nitrogen 33 in gas form and oxygen 34 in liquid form are at least partially withdrawn as products or residual gas. The gaseous impurity nitrogen 33 is heated in the supercooling countercurrent 10 and in the main heat exchanger 105a / 105c. The liquid oxygen 34 is divided into two parts. A first part 35 is withdrawn as a liquid product (LOX), optionally after partial supercooling in the subcooling countercurrent 10 (not shown).

Der zweite Teil 41 des flüssigen Sauerstoffs 34 vom Sumpf der Niederdrucksäule 3 wird - ähnlich dem flüssigen Stickstoff 111 aus der Hochdrucksäule - einer Innenverdichtung (internal compression) unterzogen, indem er in einer Pumpe 42 auf den gewünschten Produktdruck gebracht und über Leitung 43 dem Hauptwärmetauscher (Block 105a) zuströmt, wo er verdampft (beziehungsweise - bei überkritischem Produktdruck - pseudo-verdampft) und auf etwa Umgebungstemperatur angewärmt wird. Schließlich wird er über Leitung 120 als gasförmiges Sauerstoff-Druckprodukt gewonnen. Verdampfung und Anwärmung werden in indirektem Wärmeaustausch mit dem Hochdruckluftstrom 104 - 117 durchgeführt.The second part 41 of the liquid oxygen 34 from the bottom of the low pressure column 3 is - similar to the liquid nitrogen 111 from the high pressure column - subjected to an internal compression (internal compression), brought in a pump 42 to the desired product pressure and via line 43 the main heat exchanger ( Block 105a) flows in, where it evaporates (or - at supercritical product pressure - pseudo-evaporated) and is warmed to about ambient temperature. Finally, it is recovered via line 120 as a gaseous oxygen pressure product. Evaporation and heating are carried out in indirect heat exchange with the high pressure air stream 104-117.

Ein weiterer Sauerstoffstrom 93 wird direkt gasförmig aus der Niederdrucksäule 3 abgezogen, in den Wärmetauscher-Blöcken 105a, 105b angewärmt und schließlich über Leitung 94 als druckloses Gasprodukt (GOX) abgezogen.Another oxygen stream 93 is withdrawn directly in gaseous form from the low-pressure column 3, heated in the heat exchanger blocks 105a, 105b and finally withdrawn via line 94 as a non-pressurized gas product (GOX).

Über eine Argonübergangs-Leitung 48 wird eine argonhaltige Fraktion aus der Niederdrucksäule 3 in eine Rohargonrektifikation geleitet, die in dem Beispiel in zwei seriell verbundenen Rohargonsäulen 18 und 19 durchgeführt wird (so genannte geteilte Rohargonsäule). Die argonhaltige Fraktion 48 wird der ersten Rohargonsäule 18 unmittelbar über dem Sumpf gasförmig zugeleitet. Der aufsteigende Dampf reichert sich an Argon an. Das Kopfgas 81 der ersten Rohargonsäule 18 strömt zu einem ersten Teil über Leitung 49 weiter zum Sumpf der zweiten Rohargonsäule 19. Ein anderer Teil 82 des Kopfgases 81, etwa zwischen 5 und 10 %, dient als Heizmittel für den Sumpfverdampfer 27 der Krypton-Xenon-Anreicherungssäule 24, wird in dessen Verflüssigungsraum eingeleitet und dort kondensiert. Die dabei erzeugte Flüssigkeit 83 wird als Rücklaufflüssigkeit auf die erste Rohargonsäule 18 aufgegeben.Via an argon transfer line 48 an argon-containing fraction from the low-pressure column 3 is passed into a crude argon rectification, which in the example in two serially connected Rohargonsäulen 18 and 19 is performed (so-called split Rohargonsäule). The argon-containing fraction 48 is fed to the first crude argon column 18 directly above the bottom in gaseous form. The rising vapor accumulates in argon. The head gas 81 of the first crude argon column 18 flows to a first part via line 49 on to the bottom of the second crude argon column 19. Another part 82 of the top gas 81, approximately between 5 and 10%, serves as heating means for the bottom evaporator 27 of the krypton-xenon Enrichment column 24 is introduced into the liquefaction space and condensed there. The liquid 83 produced in the process is applied to the first crude argon column 18 as reflux liquid.

Am Kopf der zweiten Rohargonsäule 19 wird gasförmiges Rohargon 50 abgezogen, in den Verflüssigungsraum des Rohargon-Kopfkondensators 17 eingeleitet und dort zum großen Teil kondensiert. Die dabei erzeugte Flüssigkeit 51 wird als Rücklaufflüssigkeit auf die zweite Rohargonsäule 19 aufgegeben.At the top of the second crude argon column 19 gaseous crude argon 50 is withdrawn, introduced into the liquefaction space of the crude argon top condenser 17 and condensed there to a large extent. The liquid 51 produced in the process is applied to the second crude argon column 19 as reflux liquid.

Die im Sumpf der zweiten Rohargonsäule 19 anfallende Flüssigkeit 52 wird mittels einer Pumpe 53 über Leitung 54 zum Kopf der ersten Rohargonsäule 18 gefördert. Sumpfflüssigkeit 55 der ersten Rohargonsäule 18 strömt über eine weitere Pumpe 56 und Leitung 57 in die Niederdrucksäule 3 zurück.The resulting in the bottom of the second Rohargonsäule 19 liquid 52 is conveyed by a pump 53 via line 54 to the head of the first crude argon column 18. Bottom liquid 55 of the first crude argon column 18 flows back into the low-pressure column 3 via a further pump 56 and line 57.

Gasförmig verbliebenes Rohargon 58 aus dem Verflüssigungsraum des Kondensator-Verdampfers 17 wird in der Reinargonsäule 22 weiter zerlegt, insbesondere von leichterflüchtigen Bestandteilen wie Stickstoff befreit. Reinargonprodukt (LAR) wird über die Leitungen 59 und 60 in flüssiger Form abgezogen. Ein anderer Teil 61 der Sumpfflüssigkeit der Reinargonsäule 22 wird in dem oben erwähnten Reinargon-Verdampfer 63 mit angeschlossenem Abscheider 62 verdampft und über Leitung 64 als aufsteigender Dampf in die Reinargonsäule 22 zurückgeleitet.Gaseous remaining crude argon 58 from the liquefaction space of the condenser-evaporator 17 is further decomposed in the pure argon column 22, in particular freed of more volatile components such as nitrogen. Pure argon product (LAR) is withdrawn via lines 59 and 60 in liquid form. Another portion 61 of the bottom liquid of the pure argon column 22 is vaporized in the above-mentioned pure argon evaporator 63 with attached separator 62 and returned via line 64 as ascending steam in the pure argon column 22.

Der Kopfkondensator 21 der Reinargonsäule wird wie bereits beschrieben durch eine unterkühlte Flüssigkeit 16b gekühlt. Aus dem Verdampfungsraum des Kopfkondensators 21 werden Dampf 66 und verbliebene Flüssigkeit 65 abgezogen. Der Dampf 66 wird an geeigneter Zwischenstelle in die Niederdrucksäule 3 eingespeist. Die - praktisch Krypton- und Xenon-freie - Flüssigkeit 65 wird auf die Krypton-Xenon-Anreicherungssäule 24 aufgegeben. Im Verflüssigungsraum des Kopfkondensators 21 kondensiert Kopfgas 67 der Reinargonsäule 22 partiell. Dabei erzeugte Rücklaufflüssigkeit 68 wird auf die Reinargonsäule aufgegeben. Restdampf 69 wird in die Atmosphäre abgeblasen.The top condenser 21 of the pure argon column is cooled as already described by a supercooled liquid 16b. From the evaporation space of the top condenser 21, vapor 66 and remaining liquid 65 are withdrawn. The vapor 66 is fed into the low-pressure column 3 at a suitable intermediate point. The virtually krypton and xenon-free liquid 65 is applied to the krypton-xenon enrichment column 24. In the liquefaction space of the top condenser 21, top gas 67 of the pure argon column 22 condenses partially. there generated reflux liquid 68 is applied to the pure argon column. Residual vapor 69 is blown off into the atmosphere.

Der zweite Luftstrom 103 wird in einem Turbinen-getriebenen Nachverdichter 85 mit Nachkühler 86 weiter verdichtet, im Hauptwärmetauscher-Block 105 a auf eine Zwischentemperatur abgekühlt und in einer Luftturbine 87 arbeitsleistend entspannt. Die entspannte Luft 88 wird über Leitung 88 in die Krypton-Xenon-Anreicherungssäule 24 eingeblasen.The second air stream 103 is further compressed in a turbine-driven after-compressor 85 with aftercooler 86, cooled in the main heat exchanger block 105 a to an intermediate temperature and expanded in an air turbine 87 to perform work. The expanded air 88 is injected via line 88 into the krypton-xenon enrichment column 24.

In dem oben beschriebenen Sumpfverdampfer 27 wird Dampf erzeugt, der zusätzlich zu den Gasen 25 und 88 in der Krypton-Xenon-Anreicherungssäule 24 aufsteigt. Als Rücklaufflüssigkeit wird wie ebenfalls bereits erwähnt die Spülflüssigkeit 65 aus dem Verdampfer des Kopfkondensators 21 der Reinargonsäule 22 auf den Kopf der Krypton-Xenon-Anreicherungssäule 24 aufgegeben. (Alternativ oder zusätzlich könnte mindestens ein Teil der sauerstoffhaltigen - aber weitgehend Krypton- und Xenonfreien - Flüssigkeit 45/46 aus der Hochdrucksäule 2 als Rücklaufflüssigkeit in der Krypton-Xenon-Anreicherungssäule 24 eingesetzt werden - in der Zeichnung nicht dargestellt.) Der aus dem Sumpfverdampfer 27 aufsteigende Dampf und das über Leitung 25 eingeführte Gas sowie die Einblase-Turbinenluft 88 treten in der Krypton-Xenon-Anreicherungssäule in Gegenstrom-Stoffaustausch mit der Flüssigkeit 65, die ärmer an Krypton und Xenon ist. Dadurch werden diese Komponenten in den Sumpf gewaschen, wogegen Methan teilweise mit dem Kopfgas 84 ausgeschleust werden kann. Letzteres wird in dem Ausführungsbeispiel der Niederdrucksäule 3 an einer geeigneten Zwischenstelle zugespeist. Vom Sumpf der Krypton-Xenon-Anreicherungssäule 24 wird ein Krypton-Xenon-Konzentrat 30 in flüssiger Form entnommen (Roh-Kr/Xe), das beispielsweise einen Krypton-Gehalt von etwa 2400 ppm und einen Xenon-Gehalt von etwa 200 ppm enthält: Im Übrigen besteht das Konzentrat 30 hauptsächlich aus Sauerstoff und enthält beispielsweise noch etwa 10 bis 40 mol-% Stickstoff sowie Kohlenwasserstoffe. Das Konzentrat 30 kann in einem Flüssigtank gespeichert oder direkt einer Weiterverarbeitung zur Gewinnung von reinem Krypton und/oder Xenon zugeführt werden.In the bottom evaporator 27 described above, steam is generated which rises in addition to the gases 25 and 88 in the krypton-xenon enrichment column 24. As reflux liquid, as already mentioned, the rinsing liquid 65 from the evaporator of the top condenser 21 of the pure argon column 22 is charged to the top of the krypton-xenon enrichment column 24. (Alternatively or additionally, at least a portion of the oxygen-containing - but substantially krypton- and xenon-free - liquid 45/46 from the high pressure column 2 could be used as reflux liquid in the krypton-xenon enrichment column 24 - not shown in the drawing.) The from the bottom evaporator Rising vapor 27 and gas introduced via line 25, as well as single-jet turbine air 88, countercurrent mass transfer in the krypton-xenon enrichment column to liquid 65, which is poorer in krypton and xenon. As a result, these components are washed into the sump, while methane can be partially discharged with the head gas 84. The latter is fed in the embodiment of the low-pressure column 3 at a suitable intermediate point. From the bottom of the krypton-xenon enrichment column 24, a krypton-xenon concentrate 30 is withdrawn in liquid form (crude Kr / Xe) containing, for example, a krypton content of about 2400 ppm and a xenon content of about 200 ppm: Incidentally, the concentrate 30 mainly consists of oxygen and, for example, still contains about 10 to 40 mol% of nitrogen and hydrocarbons. The concentrate 30 may be stored in a liquid tank or directly fed to further processing to obtain pure krypton and / or xenon.

Zwischen den Blöcken 105a, 105b, 105c des Hauptwärmetauscher-Systems sind Ausgleichsströme 96, 97 vorgesehen.Balancing streams 96, 97 are provided between blocks 105a, 105b, 105c of the main heat exchanger system.

Das Ausführungsbeispiel der Figur 1 zeigt außerdem eine zusätzliche Säule 89 zur Gewinnung eines Helium-Neon-Konzentrats 90, 91 (Roh-HeNe) aus nicht kondensiertem Stickstoff-Dampf 92, der vom Hauptkondensator 4 abgezogen wird. Diese Helium-Neon-Gewinnung ist grundsätzlich unabhängig von der erfindungsgemäßen Krypton-Xenon-Gewinnung.The embodiment of FIG. 1 also shows an additional column 89 for obtaining a helium-neon concentrate 90, 91 (crude HeNe) from uncondensed nitrogen vapor 92 withdrawn from the main condenser 4. This helium-neon recovery is fundamentally independent of the krypton-xenon recovery according to the invention.

Über Leitung 101 von Figur 2 strömt komprimierte Luft (AIR) ein. Sie wird in einen ersten Luftstrom (Direktluft) 102, einen zweiten Luftstrom (Turbinenluft) 103 und einen dritten Luftstrom (Innenverdichtungsluft) 104 aufgeteilt. Der Hauptwärmetauscher weist in dem Ausführungsbeispiel zwei parallele Blöcke 105a, 105b auf. Der erste Luftstrom 102 wird in beiden Blöcken 105a und 105b des Hauptwärmetauschers auf etwa Taupunkt abgekühlt und ohne weitere druckverändernde Maßnahmen über Leitung 1 gasförmig in die Hochdrucksäule 2 eines Rektifiziersystems zur Stickstoff-Sauerstoff-Trennung eingeleitet. Das Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung weist außerdem eine Niederdrucksäule 3 und einen Hauptkondensator 4 auf, der in dem Beispiel als Fallfilmverdampfer ausgebildet ist. Gasförmiger Stickstoff 6 vom Kopf der Hochdrucksäule wird dem Kondensationsraum des Hauptkondensators 4 zugeleitet. Das dort gebildete Kondensat 7 wird in die Hochdrucksäule eingeleitet und zum Teil dort als Rücklauf verwendet. Ein anderer Teil 106 wird flüssig aus der Hochdrucksäule 2 entnommen und verzweigt bei 107 nochmals. Ein erster Zweigstrom flüssigen Stickstoffs wird in einem Unterkühlungs-Gegenströmer 10 unterkühlt, über Leitung 108 in einen Abscheider (Phasentrenner) 109 eingeleitet und schließlich über Leitung 114 als flüssiges Stickstoffprodukt (LIN) gewonnen. Ein anderer Zweigstrom 111 des flüssigen Stickstoffs vom Kopf der Hochdrucksäule 2 (beziehungsweise vom Hauptkondensator 4) wird in einer Pumpe 112 in flüssigem Zustand auf einen gewünschten Produktdruck gebracht, im Hauptwärmetauscher-Block 105a verdampft (beziehungsweise im Falle eines überkritischen Drucks pseudo-verdampft) und auf etwa Umgebungstemperatur angewärmt und über Leitung 113 als gasförmiges Druckprodukt (PGAN) abgeführt. Zur Verdampfung des flüssig auf Druck gebrachten Stickstoffs dient der dritte Luftstrom 104, der in einem Nachverdichter 115 mit Nachkühler 116 auf einen entsprechend hohen Druck gebracht wurde.Via line 101 of FIG. 2 enters compressed air (AIR). It is divided into a first air flow (direct air) 102, a second air flow (turbine air) 103 and a third air flow (internal compression air) 104. The main heat exchanger has two parallel blocks 105a, 105b in the exemplary embodiment. The first air stream 102 is cooled in both blocks 105a and 105b of the main heat exchanger to about dew point and introduced without further pressure-changing measures via line 1 in gaseous form in the high pressure column 2 of a rectification system for nitrogen-oxygen separation. The rectification system for nitrogen-oxygen separation also has a low pressure column 3 and a main condenser 4, which is formed in the example as a falling film evaporator. Gaseous nitrogen 6 from the head of the high-pressure column is fed to the condensation space of the main condenser 4. The condensate 7 formed there is introduced into the high-pressure column and used there as part of the return. Another part 106 is removed liquid from the high-pressure column 2 and branches again at 107. A first branch stream of liquid nitrogen is subcooled in a subcooler countercurrent 10, introduced via line 108 into a separator (phase separator) 109, and finally recovered via line 114 as a liquid nitrogen product (LIN). Another branch stream 111 of the liquid nitrogen from the top of the high-pressure column 2 (or main condenser 4) is brought to a desired product pressure in a liquid state pump 112, vaporized in the main heat exchanger block 105a (or pseudo-vaporized in the case of supercritical pressure) and warmed to about ambient temperature and discharged via line 113 as gaseous pressure product (PGAN). The third air stream 104, which has been brought to a correspondingly high pressure in a secondary compressor 115 with aftercooler 116, serves to vaporize the nitrogen which has been brought to liquid pressure.

Über Leitung 9 wird unreiner flüssiger Stickstoff einige theoretische Böden unterhalb des Kopfs aus der Hochdrucksäule 2 entnommen, im Unterkühlungs-Gegenströmer 10 unterkühlt und über Leitung 11 und Drosselventil 12 der Niederdrucksäule 3 am Kopf zugeführt.Via line 9, impure liquid nitrogen is taken from some theoretical plates below the top of the high pressure column 2, in the subcooling countercurrent 10 subcooled and fed via line 11 and throttle valve 12 of the low pressure column 3 at the top.

Die im Rahmen der Innenverdichtung verflüssigte oder überkritische kalte Hochdruckluft 117 wird über Ventil 118 und Leitung 44 mindestens zum Teil in flüssiger Form in die Hochdrucksäule 2 eingedrosselt, und zwar an einer "ersten Zwischenstelle" einige theoretische Böden oberhalb des Hochdrucksäulen-Sumpfs. Von einer "zweiten Zwischenstelle", die wiederum einige theoretische Böden oberhalb dieser ersten Zwischenstelle angeordnet ist, wird eine sauerstoffhaltige Flüssigkeit 45 aus der Hochdrucksäule abgezogen, die kaum noch schwererflüchtige Komponenten wie insbesondere Krypton und Xenon aufweist. Die im Unterkühlungs-Gegenströmer 10 abgekühlte Flüssigkeit 119 wird zum Teil über Leitung 46 und Drosselventil 47 in die Niederdrucksäule 3 eingespeist. Ein anderer Teil 20 der unterkühlten sauerstoffhaltigen Flüssigkeit 119 wird in den Verdampfungsraum eines Kopfkondensators 21 einer Reinargonsäule 22 eingespeist.The cold high-pressure air 117 liquefied or supercritical within the scope of internal compression is at least partly throttled into the high-pressure column 2 via valve 118 and line 44, namely at a "first intermediate point" some theoretical plates above the high-pressure column sump. From a "second intermediate point", which in turn is arranged some theoretical plates above this first intermediate point, an oxygen-containing liquid 45 is withdrawn from the high-pressure column, which hardly has any more volatile components such as in particular krypton and xenon. The cooled in the subcooling countercurrent 10 liquid 119 is partially fed via line 46 and throttle valve 47 in the low pressure column 3. Another part 20 of the supercooled oxygen-containing liquid 119 is fed into the evaporation space of a top condenser 21 of a pure argon column 22.

Die sauerstoffangereicherte Sumpfflüssigkeit 13 der Hochdrucksäule 2 wird ebenfalls im Unterkühlungs-Gegenströmer 10 abgekühlt. Die unterkühlte sauerstoffangereicherte Flüssigkeit 14 - 15 wird in einem Reinargon-Verdampfer 63 weiter abgekühlt und wird schließlich über Leitung 16 in den Verdampfungsraum eines Rohargon-Kopfkondensators 17 eingeleitet, der den Kopfkondensator einer Rohargonrektifikation 18/19 darstellt.The oxygen-enriched bottoms liquid 13 of the high-pressure column 2 is likewise cooled in the subcooling countercurrent 10. The supercooled oxygen-enriched liquid 14-15 is further cooled in a pure argon evaporator 63 and is finally introduced via line 16 into the vaporization space of a crude argon top condenser 17, which is the top condenser of crude argon rectification 18/19.

Der Rohargon-Kopfkondensator 17 ist als Umlaufverdampfer ausgebildet, das heißt der Verdampfungsraum enthält ein Flüssigkeitsbad, in das ein Wärmetauscherblock mindestens teilweise, vorzugsweise (in Abweichung von der schematischen Darstellung in der Zeichnung) vollständig eingetaucht ist. Flüssigkeit wird durch den Thermosiphon-Effekt am unteren Ende der Verdampfungspassagen angesaugt. An deren oberem Ende tritt ein Gemisch aus Dampf und unverdampfter Flüssigkeit aus, wobei letztere in das Flüssigkeitsbad zurückströmt. Im Rohargon-Kopfkondensator 17 wird die sauerstoffangereicherte Fraktion 16 partiell verdampft; beispielsweise 0,5 bis 10 mol-%, vorzugsweise 1 bis 5 mol-% der eingeführten Flüssigkeit 16 werden flüssig als Spülflüssigkeit 26 aus dem Verdampfungsraum des Rohargon-Kopfkondensators 17 abgezogen. Durch diese partielle Verdampfung wird die Konzentration von schwererflüchtigen Komponenten, insbesondere von Krypton und Xenon, in der Flüssigkeit erhöht und im Dampf vermindert (jeweils im Vergleich zur Zusammensetzung der sauerstoffangereicherten Fraktion 16). Der bei der partiellen Verdampfung erzeugte Dampf wird als gasförmiger Strom 25 aus dem Verdampfungsraum des Rohargon-Kopfkondensators 17 abgezogen. Verbleibende Flüssigkeit wird als "Spülflüssigkeit" 26 aus dem Flüssigkeitsbad abgeführt und der Krypton-Xenon-Anreicherungssäule 24 unmittelbar oberhalb des Sumpfs zugeleitet.The crude argon top condenser 17 is designed as a circulation evaporator, that is, the evaporation chamber contains a liquid bath, in which a heat exchanger block is at least partially, preferably completely immersed (in deviation from the schematic representation in the drawing). Liquid is sucked in by the thermosiphon effect at the bottom of the evaporation passages. At its upper end, a mixture of vapor and undiluted liquid emerges, the latter flowing back into the liquid bath. In the crude argon top condenser 17, the oxygen-enriched fraction 16 is partially evaporated; For example, 0.5 to 10 mol%, preferably 1 to 5 mol% of the introduced liquid 16 are withdrawn liquid as rinsing liquid 26 from the evaporation space of the crude argon top condenser 17. Due to this partial evaporation, the concentration of less volatile components, in particular of krypton and xenon, in the Increased liquid and reduced in the vapor (in each case compared to the composition of the oxygen-enriched fraction 16). The vapor generated in the partial evaporation is withdrawn as a gaseous stream 25 from the evaporation space of the crude argon top condenser 17. Remaining liquid is removed as "rinse liquid" 26 from the liquid bath and fed to the krypton-xenon enrichment column 24 immediately above the sump.

Von der Niederdrucksäule 3 werden Unreinstickstoff 33 in Gasform sowie Sauerstoff 34 in flüssiger Form mindestens teilweise als Produkte beziehungsweise Restgas abgezogen. Der gasförmige Unreinstickstoff 33 wird gemeinsam mit Flashgas 110 aus dem Abscheider 109 im Unterkühlungs-Gegenströmer 10 und im Hauptwärmetauscher 105a/105b angewärmt. Der flüssige Sauerstoff 34 wird in insgesamt drei Teile aufgeteilt. Ein erster und ein zweiter Teil werden zunächst gemeinsam über Leitung 35 und Pumpe 36 gefördert. Der erste Teil 37 strömt zum Verdampfungsraum des Hauptkondensators 4 und wird dort teilweise verdampft. Das dabei gebildete Dampf-Flüssigkeitsgemisch 38 fließt zum Sumpf der Niederdrucksäule 3 zurück. Über die Leitungen 39 und 40 wird der zweite Teil als Flüssigprodukt (LOX) abgezogen, nach teilweiser Unterkühlung im Unterkühlungs-Gegenströmer 10.From the low-pressure column 3, impure nitrogen 33 in gas form and oxygen 34 in liquid form are at least partially withdrawn as products or residual gas. The gaseous impure nitrogen 33 is heated together with flash gas 110 from the separator 109 in the subcooling countercurrent 10 and in the main heat exchanger 105a / 105b. The liquid oxygen 34 is divided into a total of three parts. A first and a second part are initially conveyed together via line 35 and pump 36. The first part 37 flows to the evaporation space of the main capacitor 4 and is partially evaporated there. The resulting vapor-liquid mixture 38 flows back to the bottom of the low-pressure column 3. Via the lines 39 and 40, the second part is withdrawn as a liquid product (LOX), after partial supercooling in the subcooling countercurrent 10th

Der dritte Teil 41 des flüssigen Sauerstoffs 34 vom Sumpf der Niederdrucksäule 3 wird - ähnlich dem flüssigen Stickstoff 111 aus der Hochdrucksäule - einer Innenverdichtung (internal compression) unterzogen, indem er in einer Pumpe 42 auf den gewünschten Produktdruck gebracht und über Leitung 43 dem Hauptwärmetauscher (Block 105a) zuströmt, wo er verdampft (beziehungsweise - bei überkritischem Produktdruck - pseudo-verdampft) und auf etwa Umgebungstemperatur angewärmt wird. Schließlich wird er über Leitung 120 als gasförmiges Sauerstoff-Druckprodukt gewonnen. Verdampfung und Anwärmung werden in indirektem Wärmeaustausch mit dem Hochdruckluftstrom 104 - 117 durchgeführt.The third part 41 of the liquid oxygen 34 from the bottom of the low pressure column 3 is - similar to the liquid nitrogen 111 from the high pressure column - subjected to an internal compression (internal compression), brought in a pump 42 to the desired product pressure and via line 43 the main heat exchanger ( Block 105a) flows in, where it evaporates (or - at supercritical product pressure - pseudo-evaporated) and is warmed to about ambient temperature. Finally, it is recovered via line 120 as a gaseous oxygen pressure product. Evaporation and heating are carried out in indirect heat exchange with the high pressure air stream 104-117.

Über eine Argonübergangs-Leitung 48 wird eine argonhaltige Fraktion aus der Niederdrucksäule 3 in eine Rohargonrektifikation geleitet, die in dem Beispiel in zwei seriell verbundenen Rohargonsäulen 18 und 19 durchgeführt wird (so genannte geteilte Rohargonsäule). Die argonhaltige Fraktion 48 wird der ersten Rohargonsäule 18 unmittelbar über dem Sumpf gasförmig zugeleitet. Der aufsteigende Dampf reichert sich an Argon an. Das Kopfgas der ersten Rohargonsäule 18 strömt über Leitung 49 weiter zum Sumpf der zweiten Rohargonsäule 19.Via an argon transfer line 48, an argon-containing fraction from the low-pressure column 3 is passed into a crude argon rectification, which in the example is carried out in two serially connected crude argon columns 18 and 19 (so-called split crude argon column). The argon-containing fraction 48 is fed to the first crude argon column 18 directly above the bottom in gaseous form. The rising steam enriches to argon. The top gas of the first crude argon column 18 continues to flow via line 49 to the bottom of the second crude argon column 19.

Am Kopf der zweiten Rohargonsäule 19 wird gasförmiges Rohargon 121 abgezogen. Ein erster Teil 50 davon, etwa 90 %, wird in den Verflüssigungsraum des Rohargon-Kopfkondensators 17 eingeleitet und dort zum großen Teil kondensiert. Die dabei erzeugte Flüssigkeit 51 wird als Rücklaufflüssigkeit auf die zweite Rohargonsäule 19 aufgegeben. Ein anderer Teil 122, etwa 10 %, des Rohargons 121, dient als Heizmittel für den Sumpfverdampfer 27 der Krypton-Xenon-Anreicherungssäule 24. Im Sumpfverdampfer 27 gebildete Flüssigkeit strömt über Leitung 123 zurück zum Kopf der zweiten Rohargonsäule 19.At the top of the second Rohargonsäule 19 gaseous crude argon 121 is withdrawn. A first part 50 thereof, about 90%, is introduced into the liquefaction space of the crude argon top condenser 17 and condensed there to a large extent. The liquid 51 produced in the process is applied to the second crude argon column 19 as reflux liquid. Another part 122, about 10%, of the crude argon 121 serves as heating means for the bottom evaporator 27 of the krypton-xenon enrichment column 24. Liquid formed in the bottom evaporator 27 flows via line 123 back to the top of the second crude argon column 19.

Die im Sumpf der zweiten Rohargonsäule 19 anfallende Flüssigkeit 52 wird mittels einer Pumpe 53 über Leitung 54 zum Kopf der ersten Rohargonsäule 18 gefördert. Sumpfflüssigkeit 55 der ersten Rohargonsäule 18 strömt über eine weitere Pumpe 56 und Leitung 57 in die Niederdrucksäule 3 zurück.The resulting in the bottom of the second Rohargonsäule 19 liquid 52 is conveyed by a pump 53 via line 54 to the head of the first crude argon column 18. Bottom liquid 55 of the first crude argon column 18 flows back into the low-pressure column 3 via a further pump 56 and line 57.

Gasförmig verbliebenes Rohargon 58 aus dem Verflüssigungsraum des Rohargon-Kopfkondensators 17 wird in der Reinargonsäule 22 weiter zerlegt, insbesondere von leichterflüchtigen Bestandteilen wie Stickstoff befreit. Reinargonprodukt (LAR) wird über die Leitungen 59 und 60 in flüssiger Form abgezogen. Ein anderer Teil 61 der Sumpfflüssigkeit der Reinargonsäule 22 wird in dem oben erwähnten Reinargon-Verdampfer 63 mit angeschlossenem Abscheider 62 verdampft und über Leitung 64 als aufsteigender Dampf in die Reinargonsäule 22 zurückgeleitet.Gaseous remaining crude argon 58 from the liquefaction of the crude argon top condenser 17 is further decomposed in the pure argon column 22, in particular freed of more volatile constituents such as nitrogen. Pure argon product (LAR) is withdrawn via lines 59 and 60 in liquid form. Another portion 61 of the bottom liquid of the pure argon column 22 is vaporized in the above-mentioned pure argon evaporator 63 with attached separator 62 and returned via line 64 as ascending steam in the pure argon column 22.

Der Kopfkondensator 21 der Reinargonsäule wird wie bereits beschrieben durch eine unterkühlte Flüssigkeit 20 gekühlt. Aus dem Verdampfungsraum des Kopfkondensators 21 werden Dampf 66 und verbliebene Flüssigkeit 65 abgezogen. Der Dampf 66 wird an geeigneter Zwischenstelle in die Niederdrucksäule 3 eingespeist. Die - praktisch Krypton- und Xenon-freie - Flüssigkeit 65 wird auf die Krypton-Xenon-Anreicherungssäule 24 aufgegeben. Im Verflüssigungsraum des Kopfkondensators 21 kondensiert Kopfgas 67 der Reinargonsäule 22 partiell. Dabei erzeugte Rücklaufflüssigkeit 68 wird auf die Reinargonsäule aufgegeben. Restdampf 69 wird in die Atmosphäre abgeblasen.The top condenser 21 of the pure argon column is cooled by a supercooled liquid 20 as already described. From the evaporation space of the top condenser 21, vapor 66 and remaining liquid 65 are withdrawn. The vapor 66 is fed into the low-pressure column 3 at a suitable intermediate point. The virtually krypton and xenon-free liquid 65 is applied to the krypton-xenon enrichment column 24. In the liquefaction space of the top condenser 21, top gas 67 of the pure argon column 22 condenses partially. This generated return fluid 68 is applied to the pure argon column. Residual vapor 69 is blown off into the atmosphere.

Der zweite Luftstrom 103 wird in einem turbinen-getriebenen Nachverdichter 85 mit Nachkühler 86 weiter verdichtet, im Hauptwärmetauscher-Block 105 a auf eine Zwischentemperatur abgekühlt und in einer Luftturbine 87 arbeitsleistend entspannt. Die entspannte Luft 88 wird über Leitung 88 in die Krypton-Xenon-Anreicherungssäule 24 eingeblasen.The second air stream 103 is further compressed in a turbine-driven booster 85 with aftercooler 86, cooled in the main heat exchanger block 105 a to an intermediate temperature and expanded in an air turbine 87 to perform work. The expanded air 88 is injected via line 88 into the krypton-xenon enrichment column 24.

In dem oben beschriebenen Rohargon-beheizten Sumpfverdampfer 27 wird Dampf erzeugt, der zusätzlich zu dem Gas 25 und der Einblase-Turbinenluft 88 in der Krypton-Xenon-Anreicherungssäule 24 aufsteigt. Als Rücklaufflüssigkeit wird wie ebenfalls bereits erwähnt die Spülflüssigkeit 65 aus dem Verdampfer des Kopfkondensators 21 der Reinargonsäule 22 auf den Kopf der Krypton-Xenon-Anreicherungssäule 24 aufgegeben. Der aus dem Sumpfverdampfer 27 aufsteigende Dampf und das über Leitung 25 eingeführte Gas treten in der Krypton-Xenon-Anreicherungssäule in Gegenstrom-Stoffaustausch mit der Flüssigkeit 65, die ärmer an Krypton und Xenon ist. Dadurch werden diese Komponenten in den Sumpf gewaschen, wogegen Methan teilweise mit dem Kopfgas 84 ausgeschleust werden kann. Letzteres wird in dem Ausführungsbeispiel der Niederdrucksäule 3 an einer geeigneten Zwischenstelle zugespeist. Vom Sumpf der Krypton-Xenon-Anreicherungssäule 24 wird ein Krypton-Xenon-Konzentrat 30 in flüssiger Form entnommen (Roh-KrXe), das beispielsweise einen Krypton-Gehalt von etwa 2400 ppm und einen Xenon-Gehalt von etwa 200 ppm enthält: Im Übrigen besteht das Konzentrat 30 hauptsächlich aus Sauerstoff und enthält noch etwa 10 mol-% Stickstoff sowie Kohlenwasserstoffe. Das Konzentrat 30 kann in einem Flüssigtank gespeichert oder direkt einer Weiterverarbeitung zur Gewinnung von reinem Krypton und/oder Xenon zugeführt werden.In the crude argon-heated bottom evaporator 27 described above, steam is generated which rises in addition to the gas 25 and the single-bladed turbine air 88 in the krypton-xenon enrichment column 24. As reflux liquid, as already mentioned, the rinsing liquid 65 from the evaporator of the top condenser 21 of the pure argon column 22 is charged to the top of the krypton-xenon enrichment column 24. The vapor rising from the bottom evaporator 27 and the gas introduced via line 25 countercurrently exchange with the fluid 65 in the krypton-xenon enrichment column, which is poorer in krypton and xenon. As a result, these components are washed into the sump, while methane can be partially discharged with the head gas 84. The latter is fed in the embodiment of the low-pressure column 3 at a suitable intermediate point. From the bottom of the krypton-xenon enrichment column 24, a krypton-xenon concentrate 30 in liquid form is withdrawn (crude KrXe) containing, for example, a krypton content of about 2400 ppm and a xenon content of about 200 ppm: Incidentally the concentrate 30 consists mainly of oxygen and still contains about 10 mol% of nitrogen and hydrocarbons. The concentrate 30 may be stored in a liquid tank or directly fed to further processing to obtain pure krypton and / or xenon.

Figur 3 unterscheidet sich hinsichtlich der Abfolge der Verfahrensschritte nicht von Figur 2. Allerdings ist die Anordnung der Krypton-Xenon-Anreicherungssäule 24 verschieden. Während sie in Figur 2 als separater Behälter oberhalb der ersten Rohargonsäule 18 angebracht ist, befindet sie sich in Figur 3 zwischen dem Rohargon-Kopfkondensator 17 und dem Stoffaustauschbereich der zweiten Rohargonsäule 19. Krypton-Xenon-Anreicherungssäule 24 und zweite Rohargonsäule 19 bilden damit gewissermaßen eine Doppelsäule mit dem zweiten Kondensator-Verdampfer als "Hauptkondensator". Da die Krypton-Xenon-Anreicherungssäule und die Rohargonsäulen 18, 19 einen ähnlichen Durchmesser aufweisen, kann eine derartige Anordnung apparativ besonders günstig sein. FIG. 3 does not differ with respect to the sequence of process steps FIG. 2 , However, the arrangement of the krypton-xenon enrichment column 24 is different. While in FIG. 2 is mounted as a separate container above the first Rohargonsäule 18, it is located in FIG. 3 Krypton-xenon enrichment column 24 and second crude argon column 19 thus form, so to speak, a double column with the second condenser-evaporator as a "main condenser" between the crude argon head condenser 17 and the mass transfer region of the second crude argon column. Since the krypton-xenon enrichment column and the Rohargonsäulen 18, 19 have a similar diameter, such an arrangement can be particularly favorable apparatus.

In den Ausführungsbeispielen der Figuren 2 und 3 sind die Krypton-Xenon-Anreicherungssäule 24, die zweite Rohargonsäule 19 und die Reinargonsäule 22 sowie deren Kondensatoren 27, 17, 21 so angeordnet, dass die Flüssigkeiten 26, 51, 65, 68 und 123 allein aufgrund des geodätischen Gefälles ihrem Ziel zuströmen. Diese Anordnung ist jedoch aus räumlichen Gründen nicht immer optimal.In the embodiments of the Figures 2 and 3 For example, the krypton-xenon enrichment column 24, the second crude argon column 19 and the pure argon column 22 and their condensers 27, 17, 21 are arranged such that the liquids 26, 51, 65, 68 and 123 flow towards their destination solely on the basis of the geodetic gradient. However, this arrangement is not always optimal for space reasons.

Bei Figur 4 ist die Reinargonsäule 22 niedriger angeordnet als in Figur 2, sodass die Flüssigkeit 65 nach oben fließen muss. Dazu wird der Verdampfungsraum des Kopfkondensators 21 der Reinargonsäule 22 unter etwas höherem Druck als in Figur 2 betrieben, sodass die Spülflüssigkeit 65 aufgrund des entsprechenden Druckgefälles in die Krypton-Xenon-Anreicherungssäule gedrückt wird. Eine entsprechende Druckdifferenz wird in der Gasleitung 66 durch die Regelklappe 294 aufrecht erhalten.at FIG. 4 the pure argon column 22 is arranged lower than in FIG. 2 so that the liquid 65 must flow upwards. For this purpose, the evaporation space of the top condenser 21 of the pure argon column 22 is under slightly higher pressure than in FIG. 2 operated, so that the rinsing liquid 65 is pressed due to the corresponding pressure gradient in the krypton-xenon enrichment column. A corresponding pressure difference is maintained in the gas line 66 through the control flap 294.

Die Reinargonsäule der Figur 5 steht ebenfalls niedriger als in Figur 2. Allerdings wird hier kein erhöhter Druck im Verdampfungsraum des Kopfkondensators 21 benötigt, da die Spülflüssigkeit 465 aus dem Kopfkondensator 21 der Reinargonsäule 22 direkt bei einer Zwischenstelle 492 in die Niederdrucksäule 3 eingeleitet wird, die tiefer als der Kondensator 21 liegt. Die Einsatzflüssigkeit 493 für die Krypton-Xenon-Anreicherungssäule wird hier bereits stromaufwärts des Kopfkondensators 21 aus der Flüssigkeit 20 abgezweigt, die über die Leitungen 45 und 119 von der zweiten Zwischenstelle der Hochdrucksäule 2 abgezogen wurde. Ein anderer Teil dieser Flüssigkeit 20 strömt in den Verdampfungsraum des Kopfkondensators 21 der Reinargonsäule 22.The pure argon column of FIG. 5 is also lower than in FIG. 2 , However, no increased pressure in the evaporation space of the top condenser 21 is required here since the flushing liquid 465 is introduced from the top condenser 21 of the pure argon column 22 directly into the low pressure column 3 at an intermediate point 492 which is lower than the condenser 21. The feed liquid 493 for the krypton-xenon enrichment column is branched off here already upstream of the top condenser 21 from the liquid 20, which was withdrawn via the lines 45 and 119 from the second intermediate point of the high-pressure column 2. Another part of this liquid 20 flows into the evaporation space of the top condenser 21 of the pure argon column 22.

Auch die Ausführungsbeispiele der nicht vorveröffentlichten deutschen Patentanmeldung 10153252 und der dazu korrespondierenden Anmeldungen in weiteren Ländern (zum Beispiel der europäischen Patentanmeldung Nr. 02001356 ) werden hier einbezogen. Sie stellen - modifiziert durch die Verwendung eines Teils des Rohargons vom Kopf der Rohargonrektifikation als Heizmittel für den Sumpfverdampfer der Krypton-Xenon-Anreicherungssäule - Ausführungsformen der Erfindung dar.Also, the embodiments of the not previously published German patent application 10153252 and the corresponding applications in other countries (for example the European Patent Application No. 02001356 ) are included here. They represent embodiments of the invention modified by the use of a portion of the crude argon from the top of the crude argon rectification as heating means for the bottom evaporator of the krypton-xenon enrichment column.

Bei allen Ausführungsformen der Erfindung kann als Hauptkondensator statt des in den Zeichnungen dargestellten Fallfilmverdampfers 4 eine Kombination aus Fallfilmverdampfer und Umlaufverdampfer eingesetzt werden, die verdampfungsseitig seriell verbunden sind. In diesem Fall kann die Erfindung einen weiteren Vorteil bewirken: Dadurch dass nur eine äußerst geringe Menge an schwererflüchtigen Bestandteilen der Luft in die Niederdrucksäule gelangt, kann die Umwälzpumpe 36 für den Fallfilmverdampfer eingespart werden.In all embodiments of the invention may be used as a main capacitor instead of the falling film evaporator 4 shown in the drawings, a combination of falling film evaporator and circulation evaporator, which are connected in series on the evaporation side. In this case, the invention can bring about a further advantage: The fact that only an extremely small amount of less volatile components of the air passes into the low pressure column, the circulation pump 36 can be saved for the falling film evaporator.

Bei einem "Fallfilmverdampfer" strömt das zu verdampfende Fluid von oben nach unten durch den Verdampfungsraum und wird dabei teilweise verdampft. Bei einem "Umlaufverdampfer" (auch Flüssigkeitsbadverdampfer) genannt steht der Wärmetauscherblock in einem Flüssigkeitsbad des zu verdampfenden Fluids. Dieses strömt mittels des Thermosiphon-Effekts von unten nach oben durch die Verdampfungspassagen und tritt oben als Zwei-Phasen-Gemisch wieder aus. Die verbleibende Flüssigkeit strömt außerhalb des Wärmetauscherblocks in das Flüssigkeitsbad zurück. (Bei einem Umlaufverdampfer kann der Verdampfungsraum sowohl die Verdampfungspassagen als auch den Außenraum um den Wärmetauscherblock umfassen.)In a "falling-film evaporator", the fluid to be evaporated flows from top to bottom through the evaporation space and is partially evaporated. In a "circulation evaporator" (also called liquid bath evaporator), the heat exchanger block is in a liquid bath of the fluid to be evaporated. This flows by means of the thermosiphon effect from bottom to top through the evaporation passages and exits the top again as a two-phase mixture. The remaining liquid flows outside the heat exchanger block back into the liquid bath. (In a circulation evaporator, the evaporation space may include both the evaporation passages and the outside space around the heat exchanger block.)

Claims (8)

  1. Process for obtaining krypton and/or xenon by cryogenic fractionation of air, in which
    • a first compressed and cleaned feed air stream (1) is introduced into a rectifying system for nitrogen-oxygen separation, which has at least one high-pressure column (2) and one low-pressure column (3), by
    • feeding a krypton- and xenon-containing fraction (26) which has a higher molar krypton and/or xenon concentration than the feed air stream to the lower or middle region of a krypton-xenon enrichment column (24),
    • withdrawing a krypton-xenon concentrate (30) from the krypton-xenon enrichment column (24) and
    • decompressing a second compressed and cleaned feed air stream (103) so as to perform work,
    characterized in that the second feed air stream (88) is introduced into the krypton-xenon enrichment column (24) downstream of the decompression (87) thereof to perform work.
  2. Process according to Claim 1, characterized in that
    • an argon-containing fraction (48) from the low-pressure column (2) is introduced into a crude argon rectification (18, 19),
    • a liquid from the lower region of the krypton-xenon enrichment column (24) is introduced into a reboiler (27) and at least partly evaporated there and
    • an argon-enriched vapour (81, 82) from an intermediate region of the crude argon rectification (18, 19), in the reboiler (27), indirectly exchanges heat with the liquid from the lower region of the krypton-xenon enrichment column (24).
  3. Process according to Claim 2, characterized in that the crude argon rectification is performed in a multitude n (n ≥ 2) of crude argon columns (18, 19) connected in series, the argon-enriched vapour being formed by a portion (82) of the top vapour (81) of the first to (n-1)th crude argon column (18).
  4. Process according to either of Claims 2 and 3, characterized in that at least a portion of the top vapour of the crude argon rectification or the top vapour (50) of the nth crude argon column (19) is introduced into the liquefaction space of a crude argon top condenser (17) and is liquefied there at least partly by indirect heat exchange with a fraction (16a) which evaporates in the evaporation space of the crude argon top condenser.
  5. Process according to Claim 4, characterized in that a purge liquid (26) is drawn off the evaporation space of the crude argon top condenser (17) and fed as a krypton- and xenon-containing fraction to the krypton-xenon enrichment column (24).
  6. Process according to Claim 5, characterized in that at least a portion of the vapour (25) formed in the evaporation space of the crude argon top condenser (17) is introduced into the krypton-xenon enrichment column (24).
  7. Apparatus for obtaining krypton and/or xenon by cryogenic fractionation of air
    • with a first feed air line (1) for introduction of compressed and pre-cleaned feed air into a rectifying system for nitrogen-oxygen separation, which has at least one high-pressure column (2) and a low-pressure column (3),
    • with a feed line (26) for introduction of a krypton- and xenon-containing fraction which has a higher molar krypton and/or xenon concentration than the feed air stream into the lower or middle region of a krypton-xenon enrichment column (24),
    • said krypton-xenon enrichment column (24) having a product line (30) for a krypton-xenon concentrate,
    • with a second feed air line (103, 88) which leads through means (87) for decompression to perform work,
    characterized in that the second feed air line (103, 88) opens into the krypton-xenon enrichment column (24) downstream of the means (87) for decompression to perform work.
  8. Apparatus according to Claim 7, characterized by
    • a crude argon rectification (18, 19) with flow connection to the low-pressure column (2),
    • a reboiler (27) which has an evaporation space and a liquefaction space, the evaporation space of the reboiler being in flow connection to the lower region of the krypton-xenon enrichment column (24) and
    • means of introducing an argon-enriched vapour (81, 82) from an intermediate region of the crude argon rectification (18, 19) into the liquefaction space of the reboiler (27).
EP20040011942 2003-05-28 2004-05-19 Process and device for the recovery of Krypton and/or Xenon by cryogenic separation of air Not-in-force EP1482266B1 (en)

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DE2003134560 DE10334560A1 (en) 2003-05-28 2003-07-29 Method for recovering krypton and xenon from air, comprises separating nitrogen and oxygen and feeding krypton- and xenon-containing fraction into enrichment column, stream of pure air being decompressed and fed into column
EP20040011942 EP1482266B1 (en) 2003-05-28 2004-05-19 Process and device for the recovery of Krypton and/or Xenon by cryogenic separation of air

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DE10324542 2003-05-28
DE10324542 2003-05-28
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DE2003134560 DE10334560A1 (en) 2003-05-28 2003-07-29 Method for recovering krypton and xenon from air, comprises separating nitrogen and oxygen and feeding krypton- and xenon-containing fraction into enrichment column, stream of pure air being decompressed and fed into column
EP03022546 2003-10-02
EP03022546 2003-10-02
EP20040011942 EP1482266B1 (en) 2003-05-28 2004-05-19 Process and device for the recovery of Krypton and/or Xenon by cryogenic separation of air

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DE102010052545A1 (en) 2010-11-25 2012-05-31 Linde Aktiengesellschaft Method and apparatus for recovering a gaseous product by cryogenic separation of air
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CN102788476B (en) * 2012-05-23 2014-08-06 苏州制氧机有限责任公司 Air separation technology for mainly producing high-purity nitrogen and accessorily producing liquid oxygen by using cryogenic air separation device
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EP2963367A1 (en) 2014-07-05 2016-01-06 Linde Aktiengesellschaft Method and device for cryogenic air separation with variable power consumption
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KR20170070172A (en) * 2014-10-16 2017-06-21 린데 악티엔게젤샤프트 Method and device for variably obtaining argon by means of low-temperature separation
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