EP1189001B1 - Process and apparatus for the production of high purity nitrogen through cryogenic air separation - Google Patents

Process and apparatus for the production of high purity nitrogen through cryogenic air separation Download PDF

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Publication number
EP1189001B1
EP1189001B1 EP00124031A EP00124031A EP1189001B1 EP 1189001 B1 EP1189001 B1 EP 1189001B1 EP 00124031 A EP00124031 A EP 00124031A EP 00124031 A EP00124031 A EP 00124031A EP 1189001 B1 EP1189001 B1 EP 1189001B1
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Prior art keywords
nitrogen
column
cycle
purity nitrogen
purity
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EP00124031A
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German (de)
French (fr)
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EP1189001A1 (en
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Ralph Dipl.-Ing. Spöri
Stefan Dipl.-Ing. Lochner
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Linde GmbH
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Linde GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/04218—Parallel arrangement of the main heat exchange line in cores having different functions, e.g. in low pressure and high pressure cores
    • F25J3/04224—Cores associated with a liquefaction or refrigeration cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04351—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
    • F25J3/04357—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen and comprising a gas work expansion loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04387—Details relating to the work expansion, e.g. process parameter etc. using liquid or hydraulic turbine expansion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
    • 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
    • F25J3/04436—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 at least a triple pressure main column system
    • F25J3/04454—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 at least a triple pressure main column system a main column system not otherwise provided, e.g. serially coupling of columns or more than three pressure levels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/32—Processes or apparatus using separation by rectification using a side column fed by a stream from the 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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/34—Processes or apparatus using separation by rectification using a side column fed by a stream from the low 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/42—Nitrogen or special cases, e.g. multiple or low purity N2
    • F25J2215/44—Ultra high purity nitrogen, i.e. generally less than 1 ppb impurities
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/42—Separating low boiling, i.e. more volatile components from nitrogen, e.g. He, H2, Ne
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/44—Separating high boiling, i.e. less volatile components from nitrogen, e.g. CO, Ar, O2, hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/42—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/12—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/04—Down-flowing type boiler-condenser, i.e. with evaporation of a falling liquid film

Definitions

  • the invention relates to a method for producing high-purity nitrogen by Cryogenic air separation according to the preamble of claim 1.
  • the invention also relates to a device according to the preamble of Claim 13.
  • Such a method and such a device are known from US-A-5596886. It points next to one Rectification system for nitrogen-oxygen separation on a high-purity nitrogen column, in the nitrogen fraction used in the rectification system for nitrogen-oxygen separation was obtained, the highly pure product is produced by the CO content is reduced by rectification.
  • the rectification system for nitrogen-oxygen separation can be a one, two or Be designed multi-column system.
  • a classic Linde double-column process is preferred for use.
  • the basics of cryogenic decomposition of air in general and the construction of double-column systems in particular are from the monograph "Low Temperature Technology” by Hausen / Linde (2nd edition, 1985) or from an article by Latimer in Chemical Engineering Progress (Vol. 63, No.2, 1967, page 35).
  • the rectification system for nitrogen-oxygen separation can in the method according to the invention further devices for Extraction of other air components, in particular of highly pure oxygen or of noble gases such as argon.
  • a process for the rectification of high purity nitrogen with reduced CO content is known from European patent EP 299364 B1.
  • the CO removal and possibly the argon removal takes place in the upper one Area of the high pressure part of the double column for nitrogen-oxygen separation instead.
  • the disadvantage of this method is that only a small part of the total Nitrogen product can be obtained in highly pure form; the majority must be Nitrogen of ordinary purity, especially without reducing the CO content (and possibly the argon content).
  • the invention has for its object a method and a device specify where a particularly high proportion of the nitrogen product in highly pure Form can be obtained, especially with a reduced CO concentration.
  • the inventive method practically any turnover in the High purity nitrogen column can be achieved by following the nitrogen cycle accordingly is designed or driven.
  • This enables flexible adaptation the process to specific customer needs. For example, it is possible that to produce entire usable nitrogen product in highly pure form without Nitrogen of ordinary purity is a by-product. This is particularly the case with the - frequently occurring - introduction of the products of the process into liquid tanks inexpensive because instead of the two nitrogen tanks required for the prior art different purities now a tank for the high purity nitrogen can suffice.
  • the generated one Amount of high purity nitrogen can be varied during operation.
  • At least a first partial stream of the liquefied cycle nitrogen is preferred in the rectification system for nitrogen-oxygen separation, especially in the first rectification column, returned: this allows the generated in the circuit Cold for the extraction of liquid products directly from the rectification system Nitrogen-oxygen separation can be used. Here, for example, it becomes more fluid Generic nitrogen and / or liquid oxygen.
  • the integration between the circulatory system and the high-purity nitrogen column can continue be reinforced by the gaseous insert for the high-purity nitrogen column is at least partially removed from the nitrogen cycle.
  • a the second part of the compressed cycle nitrogen expanded and into one High-purity nitrogen column initiated.
  • the relaxation of the second part of the compressed cycle nitrogen is preferably carried out while performing work.
  • a particularly low concentration is more volatile Impurities such as hydrogen, neon and / or helium in the high purity nitrogen product he wishes.
  • the cycle nitrogen is at least a theoretical or practical floor below the head of the first rectification column is removed and / or the high purity nitrogen at least a theoretical or practical floor below the head of the High purity nitrogen column is removed.
  • the Operating pressure at the top of the high-purity nitrogen column is, for example, the same Pressure at the head of the first rectification column.
  • the second partial stream of the liquefied cycle nitrogen can be directly from the Circuit to the evaporation chamber of the top condenser of the high-purity nitrogen column be performed. However, it is preferably first placed in the high-purity nitrogen column initiated, withdrawn from the lower area of the high-purity nitrogen column and then the evaporation in the top condenser of the high-purity nitrogen column fed.
  • the first partial stream of the liquefied cycle nitrogen can also flow into the High purity nitrogen column can be initiated - for example, together with the second partial flow. He will then also be from the bottom of the High-purity nitrogen column pulled off and then into the rectification system Nitrogen-oxygen separation returned.
  • the liquefied cycle nitrogen (first part of the compressed cycle nitrogen) must be upstream of its division into the first and second substreams or its introduction into the first rectification column can be relaxed.
  • This expansion step can be carried out using a throttle valve.
  • the corresponding partial flow of the cycle nitrogen for example in a supercritical state in a turbine and is without it Phase transition relaxes to a subcritical pressure, making it complete liquid or essentially completely liquid (gas content, for example, up to about 5%) emerges from the turbine.
  • the turbine can also be charged already liquid circulating nitrogen possible under subcritical pressure.
  • the first and the second partial stream of the first part of the Cycle nitrogen relaxed together to perform work, then together in the high-purity nitrogen column initiated; downstream of the high purity nitrogen column the division into the first and second partial stream then takes place.
  • a two-turbine circuit is preferably used, in which a third part of the compressed cycle nitrogen relieved work and at least partially is returned to the circuit compressor, the inlet temperature of the work-relieving relaxation of the third part of the compressed cycle nitrogen higher than the inlet temperature of the work relaxation of the second part of the compressed cycle nitrogen.
  • the fraction in the high-purity nitrogen column is worked up further, flows through the cold turbine.
  • the third sub-stream is preferably after the work-related relaxation at the entry of the Recycle compressor returned, for example, together with the cycle nitrogen from the first rectification column.
  • outlet pressure of the work-related relaxation of the third part of the compressed cycle nitrogen lower than the outlet pressure of the work-relieving relaxation of the second part of the compressed cycle nitrogen is.
  • this mode of operation enables particularly efficient operation of the two turbines in which gaseous nitrogen is expanded; on the other hand becomes the higher pressure of the second part to operate the high-purity nitrogen column exploited.
  • the invention also relates to a device for producing high-purity nitrogen by low-temperature air separation according to claim 10.
  • a high-pressure column 4 Compressed to a pressure of 6.5 bar and by water vapor and carbon dioxide cleaned air 1 is cooled in a main heat exchanger 2 to about dew point and fed via a line 3 to a high-pressure column 4, which in the example is the represents "first rectification column".
  • the high pressure column 4 is part of the rectification system for nitrogen-oxygen separation, which is also a low-pressure column 5 includes.
  • the two columns 4 and 5 are here under a pressure of 6.2 bar or 1.3 bar (each at the head) operated. You are above one Main condenser 6 in heat-exchanging connection. There is 7 nitrogen High pressure column 4 against evaporating sump liquid of the low pressure column 5 condensed; the condensate 8 thus formed is the high pressure column 4 as a return given up.
  • Liquid nitrogen is discharged from the high-pressure column 4 via line 18, specifically two bottoms 76 below the head. (These plywood floors are used to hold back more volatile impurities that are present as a non-condensable gas Drain not shown on the main condenser can be deducted.)
  • the liquid nitrogen 18 is subcooled in a subcooling countercurrent 10, by means of a throttle valve 19 relaxed to just above low pressure column pressure and in a separator 20 initiated. Flash gas 21 from the separator is the Head nitrogen 14 mixed. Liquid is removed from the separator 20 via line 22 fed to the low pressure column as a return. If desired, you can also here A liquid product (LIN) is drawn off via line 23.
  • LIN liquid product
  • the oxygen-enriched bottom liquid 9 is in the supercooling counterflow 10 supercooled and introduced into the low-pressure column 5 via a throttle valve 11.
  • liquid oxygen 12 is drawn off and if necessary after subcooling in the subcooling countercurrent 10 via line 13 deducted as a liquid product (LOX).
  • LOX liquid product
  • it can be gaseous Oxygen can be removed from the lower region of the low-pressure column 5.
  • Purity taken from that in the example 150 ppm of less volatile Contains components, especially argon and CO.
  • the high pressure column 4 is connected to a nitrogen cycle.
  • the removal takes place in the Example at the same intermediate point at which the liquid nitrogen 18 for the Low pressure column is removed, namely below the blocking floors 76.
  • On the Barrier floors 76 can also be dispensed with; in this case the Circulating nitrogen from the first rectification column at the top.
  • At least a part 25 of the gaseous cycle nitrogen is in the main heat exchanger 2 to about Ambient temperature warmed and via the lines 26, 27, 28, 29 the entrance a circuit compressor 30 supplied, where it is compressed to about 30 bar.
  • a first circuit heat exchanger 34a which together with a second, partially connected circuit heat exchanger 34b, a circuit heat exchanger system forms.
  • the cooled first part 35 of the compressed cycle nitrogen enters supercritical state in a liquid turbine 36 and is there to perform work 6.5 bar relaxed.
  • the liquid turbine 36 is equipped with a mechanical braking device 37 connected, for example with a generator or an oil brake.
  • the relaxed first part 38 of the cycle nitrogen is now in the liquid State and is fed into a high purity nitrogen column 39, one or several soils above their swamps (or just above the swamp of the High purity nitrogen column). It is immediately removed again via line 40.
  • a first one Partial stream 42 is fed back into the high-pressure column 4, whereby the Nitrogen cycle closes. If necessary, a pump 41 to promote the liquefied first part 40 of the cycle nitrogen are used.
  • a second part of the cycle nitrogen compressed in the cycle compressor 30 is via lines 43 and 48 together with the first part through the booster 44 and 46 and is then in two branch flows (through lines 33 - 50a or 49 - 50b) in the circuit heat exchanger system 34a, 34b to about Cooled down to 170 K.
  • the second part of the cycle nitrogen via the lines 50a and 50b to a cold turbine 51 and there to work at about 6.5 bar relaxed.
  • the relaxed second part 52 of the cycle nitrogen serves as gaseous use for the high-purity nitrogen column 39 and is immediately above fed into the swamp. It forms the ascending in the high-purity nitrogen column 39 Steam.
  • the countercurrent within the high-purity nitrogen column 39 makes it heavier volatile components such as CO and / or argon from the gaseous Washed out nitrogen.
  • the top gas 53 of the high-purity nitrogen column 39 is in a top condenser 54 is practically completely condensed (except for one shown discharge for more volatile components).
  • the condensate 55 flows as Return back to the high-purity nitrogen column 39.
  • the top condenser 54 is through cooled a partial flow 67 of the liquefied first part 40 of the cycle nitrogen.
  • the steam 68 formed in the process is heated in the first circuit heat exchanger 34 and via lines 69, 28 and 29 to the inlet of the circuit compressor 30 recycled.
  • the two circuit heat exchangers 34a, 34b can also be used as one shared block (not shown).
  • Highly pure nitrogen is withdrawn in liquid form via line 56. To withhold more volatile components serve two to three blocking floors 57 above the Product withdrawal.
  • the liquid, highly pure nitrogen 56 continues to flow via line 57 to the supercooling counterflow 10.
  • the supercooled high-purity nitrogen 58 is in a throttle valve 59 relaxed to 1.4 bar and introduced into a separator 60. Flash gas 61 from the separator 60 becomes the top nitrogen 14 of the low pressure column 5 added.
  • the liquid from the separator 60 is high via line 62 pure nitrogen product (HLIN) deducted.
  • the nitrogen cycle is also from the top nitrogen 14 of the low pressure column 5th fed, which after heating in the supercooling counterflow 10 and in Main heat exchanger 2 is fed via line 63 to a feed gas compressor 64. After compression to about the inlet pressure of the circuit compressor 30 and Aftercooling 65 it flows via lines 66 and 29 to the circuit compressor.
  • a third part 70 of the cycle nitrogen compressed in the cycle compressor 30 becomes in two branches 71a-72a and 71b - 72b in the cycle heat exchanger system 34a, 34b cooled to about 260 K. At this temperature it passes over Line 72 into a warm turbine 73 and is working there to about 6 bar relaxed. The relaxed third part of the cycle nitrogen is via the lines 74a and 74b again to the circuit heat exchanger system 34a, 34b and flows back to the circuit compressor 30 after it has warmed up.
  • the mechanical energy generated in the two gaseous turbines 51, 73 is generated, is used to drive the post-compressor 44, 46.
  • These are preferably Turbines and post-compressors are directly mechanically coupled.
  • the Turbines 51, 73 are braked by generators; in this case the whole Recycle nitrogen is only compressed in the recycle compressor 30 (not ) Shown.
  • Equalizing currents 76, 77 serve to optimize the heat transfer in the three Heat exchanger blocks 34a, 34b.
  • the method according to the invention can be compared to the exemplary embodiment in can be varied in many ways.
  • this liquid can also be at least partially directly in the Evaporation space of the top condenser 54 of the high-purity nitrogen column or in the High pressure column 4 are initiated. In the latter case, the refrigerant for the Top condenser 54 can be removed from the high pressure column 4.

Abstract

Production of highly pure nitrogen in a low temperature air decomposition rectification system comprises passing gaseous circulating nitrogen to the upper region of a first rectification column; compressing in a compressor; liquefying a first part of the compressed nitrogen; feeding a nitrogen fraction from the rectification system for nitrogen-oxygen separation to a highly pure nitrogen column. Production of highly pure nitrogen in a low temperature air decomposition rectification system comprises passing gaseous circulating nitrogen (24) to the upper region of a first rectification column (4); compressing in a compressor (30); liquefying a first part (35) of the compressed nitrogen; feeding a nitrogen fraction (52) from the rectification system for nitrogen-oxygen separation to a highly pure nitrogen column (39) containing a head condenser; removing highly pure nitrogen (56) from the upper region of the highly pure nitrogen column; and covering the cold requirement of the head condenser partially by the liquefied circulating nitrogen (38). An Independent claim is also included for a system for producing highly pure nitrogen by a low temperature air decomposition. Preferred Features: At least one first partial stream (42) of the liquefied circulating nitrogen is fed back to the rectification system, especially to the first rectification column. A second part of the compressed circulating nitrogen is released and fed to the highly pure nitrogen column. The circulating nitrogen is withdrawn a theoretical and/or practical plate below the head of the first rectification column.

Description

Die Erfindung betrifft ein Verfahren zur Erzeugung hoch reinen Stickstoffs durch Tieftemperatur-Luftzerlegung gemäß dem Oberbegriff des Patentanspruchs 1. Die Erfindung betrifft auch eine Vorrichtung gemäß dem Oberbegriff des Anspruchs 13. Ein derartiges Verfahren und eine derartige Vorrichtung sind aus der US-A-5596886 bekannt. Es weist neben einem Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung eine Hochreinstickstoff-Säule auf, in der aus einer Stickstofffraktion, die in dem Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung gewonnen wurde, das hoch reine Produkt erzeugt wird, indem der CO-Gehalt mittels Rektifikation reduziert wird.The invention relates to a method for producing high-purity nitrogen by Cryogenic air separation according to the preamble of claim 1. The invention also relates to a device according to the preamble of Claim 13. Such a method and such a device are known from US-A-5596886. It points next to one Rectification system for nitrogen-oxygen separation on a high-purity nitrogen column, in the nitrogen fraction used in the rectification system for nitrogen-oxygen separation was obtained, the highly pure product is produced by the CO content is reduced by rectification.

Das Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung kann als Ein-, Zwei- oder Mehr-Säulen-System ausgebildet sein. Vorzugsweise kommt ein klassisches Linde-Doppelsäulen-Verfahren zum Einsatz. Die Grundlagen der Tieftemperaturzerlegung von Luft im Allgemeinen sowie der Aufbau von Doppelsäulenanlagen im Speziellen sind aus der Monografie "Tieftemperaturtechnik" von Hausen/Linde (2. Auflage, 1985) oder aus einem Aufsatz von Latimer in Chemical Engineering Progress (Vol. 63, No.2, 1967, Seite 35) bekannt. Zusätzlich zu dem Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung können bei dem erfindungsgemäßen Verfahren weitere Vorrichtungen zur Gewinnung anderer Luftkomponenten, insbesondere von hoch reinem Sauerstoff oder von Edelgasen wie beispielsweise Argon eingesetzt werden.The rectification system for nitrogen-oxygen separation can be a one, two or Be designed multi-column system. A classic Linde double-column process is preferred for use. The basics of cryogenic decomposition of air in general and the construction of double-column systems in particular are from the monograph "Low Temperature Technology" by Hausen / Linde (2nd edition, 1985) or from an article by Latimer in Chemical Engineering Progress (Vol. 63, No.2, 1967, page 35). In addition to the rectification system for nitrogen-oxygen separation can in the method according to the invention further devices for Extraction of other air components, in particular of highly pure oxygen or of noble gases such as argon.

Ein Verfahren zur rektifikatorischen Gewinnung von hoch reinem Stickstoff mit verringertem CO-Gehalt ist aus dem europäischen Patent EP 299364 B1 bekannt. Die CO-Entfernung und gegebenenfalls die Argon-Entfernung findet dabei im oberen Bereich des Hochdruckteils der Doppelsäule zur Stickstoff-Sauerstoff-Trennung statt. Nachteil dieses Verfahrens ist, dass lediglich ein geringer Teil des gesamten Stickstoffprodukts in hoch reiner Form gewonnen werden kann; der Großteil muss als Stickstoff gewöhnlicher Reinheit, insbesondere ohne Reduzierung des CO-Gehalts (und gegebenenfalls des Argon-Gehalts), abgezogen werden.A process for the rectification of high purity nitrogen with reduced CO content is known from European patent EP 299364 B1. The CO removal and possibly the argon removal takes place in the upper one Area of the high pressure part of the double column for nitrogen-oxygen separation instead. The disadvantage of this method is that only a small part of the total Nitrogen product can be obtained in highly pure form; the majority must be Nitrogen of ordinary purity, especially without reducing the CO content (and possibly the argon content).

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren und eine Vorrichtung anzugeben, bei denen ein besonders hoher Anteil des Stickstoffprodukts in hoch reiner Form gewonnen werden kann, insbesondere mit verminderter CO-Konzentration. The invention has for its object a method and a device specify where a particularly high proportion of the nitrogen product in highly pure Form can be obtained, especially with a reduced CO concentration.

Diese Aufgabe wird durch die Merkmale des Patentanspruchs 1 gelöst. Hierbei wird eine Hochreinstickstoff-Säule eingesetzt, deren Kältebedarf aus dem flüssigen Stickstoff gedeckt wird, der in einem Stickstoff-Kreislauf erzeugt wird. Ein solcher Kreislauf dient zur Erzeugung großer Mengen an Flüssigprodukt und ist an sich bekannt. Wesentlicher Gedanke der Erfindung ist die vorteilhafte Verbindung dieses Verflüssigungskreislaufs mit der Hochreinstickstoff-Säule.This object is achieved by the features of patent claim 1. Here will a high-purity nitrogen column is used, whose cooling requirement comes from the liquid Nitrogen is generated, which is generated in a nitrogen cycle. Such a The cycle is used to produce large quantities of liquid product and is in itself known. The essential idea of the invention is the advantageous connection of this Liquefaction cycle with the high-purity nitrogen column.

Für die Übertragung der Kälte aus dem verflüssigten Kreislauf-Stickstoff auf die Kopffraktion der Hochreinstickstoff-Säule sind folgende Varianten möglich, die grundsätzlich auch in jeder Kombination verwirklicht werden können:

  • i) Unmittelbare Einleitung des verflüssigten Kreislauf-Stickstoffs in den Verdampfungsraum des Kopfkondensators der Hochreinstickstoff-Säule
  • ii) Einleitung des verflüssigten Kreislauf-Stickstoffs in die Hochreinstickstoff-Säule (am Sumpf oder einige Böden darüber), Entnahme einer Flüssigkeit aus der Hochreinstickstoff-Säule (beispielsweise am Sumpf) und Einleitung dieser Flüssigkeit (deren Zusammensetzung derjenigen des verflüssigten Kreislauf-Stickstoffs sehr ähnlich oder gleich ist) in den Verdampfungsraum des Kopfkondensators der Hochreinstickstoff-Säule
  • iii) Einleitung des verflüssigten Kreislauf-Stickstoffs in ein anderes Gefäß (beispielsweise die erste Rektifiziersäule), Entnahme einer Flüssigkeit gleicher oder ähnlicher Zusammensetzung aus diesem Gefäß und Einleitung dieser Flüssigkeit (deren Zusammensetzung derjenigen des verflüssigten Kreislauf-Stickstoffs sehr ähnlich oder gleich ist) in den Verdampfungsraum des Kopfkondensators der Hochreinstickstoff-Säule
    • die mit einer ersten Rektifiziersäule des Rektifiziersystems zur Stickstoff-Sauerstoff-Trennung nicht direkt, sondern über einen Stickstoff-Kreislauf in Verbindung steht. Hierzu wird die Hochreinstickstoff-Säule aus der oder einer der Entspannungsturbinen des Stickstoff-Kreislaufs mit gasförmigem Kreislauf-Stickstoff gespeist, der vorzugsweise in den unteren Bereich der Hochreinstickstoff-Säule eingeführt wird. Innerhalb der Hochreinstickstoff-Säule wird der aufsteigende Dampf durch Gegenstrom-Rektifikation an schwerer flüchtigen Bestandteilen, insbesondere CO und/oder Argon, abgereichert. Dem oberen Bereich der Hochreinstickstoff-Säule wird das entsprechend hoch reine Stickstoffprodukt entnommen. Aufgrund des vorhandenen Kreislaufs kann ein Teil oder vorzugsweise das gesamte hoch reine Stickstoffprodukt in flüssiger Form entnommen und beispielsweise in einen Tank eingeführt werden.The following variants are possible for transferring the cold from the liquefied cycle nitrogen to the top fraction of the high-purity nitrogen column, which can in principle also be implemented in any combination:
  • i) Immediate introduction of the liquefied cycle nitrogen into the evaporation space of the top condenser of the high-purity nitrogen column
  • ii) Introducing the liquefied nitrogen into the high-purity nitrogen column (at the bottom or some floors above it), withdrawing a liquid from the high-purity nitrogen column (e.g. at the bottom) and introducing this liquid (the composition of which is very similar to that of the liquefied nitrogen) or is the same) in the evaporation space of the top condenser of the high-purity nitrogen column
  • iii) introducing the liquefied nitrogen into another vessel (for example the first rectification column), withdrawing a liquid of the same or a similar composition from this vessel and introducing this liquid (the composition of which is very similar or identical to that of the liquefied nitrogen) into the Evaporation chamber of the top condenser of the high-purity nitrogen column
    • which is not directly connected to a first rectification column of the rectification system for nitrogen-oxygen separation, but via a nitrogen cycle. For this purpose, the high-purity nitrogen column is fed from the or one of the expansion turbines of the nitrogen circuit with gaseous circulating nitrogen, which is preferably introduced into the lower region of the high-purity nitrogen column. Within the high-purity nitrogen column, the rising steam is depleted by countercurrent rectification of less volatile components, especially CO and / or argon. The correspondingly high-purity nitrogen product is taken from the upper area of the high-purity nitrogen column. Due to the existing circuit, some or preferably all of the highly pure nitrogen product can be removed in liquid form and introduced, for example, into a tank.

    Durch die Integration des Kreislaufs und der Hochreinstickstoff-Säule kann bei dem erfindungsgemäßen Verfahren praktisch jeder beliebige Umsatz in der Hochreinstickstoff-Säule erreicht werden, indem der Stickstoff-Kreislauf entsprechend ausgelegt beziehungsweise gefahren wird. Dies ermöglicht eine flexible Anpassung des Prozesses an spezifische Kundenbedürfnisse. Beispielsweise ist es möglich, das gesamte verwertbare Stickstoffprodukt in hoch reiner Form zu erzeugen, ohne dass Stickstoff gewöhnlicher Reinheit als Nebenprodukt anfällt. Dies ist insbesondere bei der - häufig vorkommenden - Einführung der Produkte des Prozesses in Flüssigtanks günstig, da statt der beim Stand der Technik notwendigen zwei Stickstofftanks für die unterschiedlichen Reinheiten nunmehr ein Tank für den hoch reinen Stickstoff ausreichen kann. Außerdem kann mit dem erfindungsgemäßen Verfahren die erzeugte Menge an hoch reinem Stickstoff während des Betriebs variiert werden.By integrating the circuit and the high-purity nitrogen column, the inventive method practically any turnover in the High purity nitrogen column can be achieved by following the nitrogen cycle accordingly is designed or driven. This enables flexible adaptation the process to specific customer needs. For example, it is possible that to produce entire usable nitrogen product in highly pure form without Nitrogen of ordinary purity is a by-product. This is particularly the case with the - frequently occurring - introduction of the products of the process into liquid tanks inexpensive because instead of the two nitrogen tanks required for the prior art different purities now a tank for the high purity nitrogen can suffice. In addition, with the method according to the invention, the generated one Amount of high purity nitrogen can be varied during operation.

    Vorzugsweise wird mindestens ein erster Teilstrom des verflüssigten Kreislauf-Stickstoffs in das Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung, insbesondere in die erste Rektifiziersäule, zurückgeleitet: Hierdurch kann die im Kreislauf erzeugte Kälte zur Gewinnung von Flüssigprodukten unmittelbar aus dem Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung genutzt werden. Hierbei wird beispielsweise flüssiger Stickstoff gewöhnlicher Reinheit und/oder flüssiger Sauerstoff erzeugt.At least a first partial stream of the liquefied cycle nitrogen is preferred in the rectification system for nitrogen-oxygen separation, especially in the first rectification column, returned: this allows the generated in the circuit Cold for the extraction of liquid products directly from the rectification system Nitrogen-oxygen separation can be used. Here, for example, it becomes more fluid Generic nitrogen and / or liquid oxygen.

    Die Integration zwischen Kreislaufsystem und Hochreinstickstoff-Säule kann weiter verstärkt werden, indem der gasförmige Einsatz für die Hochreinstickstoff-Säule mindestens teilweise aus dem Stickstoff-Kreislauf entnommen wird. Dazu wird ein zweiter Teil des verdichteten Kreislauf-Stickstoffs entspannt und in eine Hochreinstickstoff-Säule eingeleitet. Die Entspannung des zweiten Teils des verdichteten Kreislauf-Stickstoffs wird vorzugsweise arbeitsleistend durchgeführt.The integration between the circulatory system and the high-purity nitrogen column can continue be reinforced by the gaseous insert for the high-purity nitrogen column is at least partially removed from the nitrogen cycle. For this, a the second part of the compressed cycle nitrogen expanded and into one High-purity nitrogen column initiated. The relaxation of the second part of the compressed cycle nitrogen is preferably carried out while performing work.

    In vielen Fällen ist auch eine besonders niedrige Konzentration von leichter flüchtigen Verunreinigungen wie Wasserstoff, Neon und/oder Helium im hoch reinen StickstoffProdukt erwünscht. Hierzu ist es vorteilhaft, wenn der Kreislauf-Stickstoff mindestens einen theoretischen beziehungsweise praktischen Boden unterhalb des Kopfs der ersten Rektifiziersäule entnommen wird und/oder der hoch reine Stickstoff mindestens einen theoretischen beziehungsweise praktischen Boden unterhalb des Kopfs der Hochreinstickstoff-Säule entnommen wird. Vorzugsweise befinden sich am Kopf der ersten Rektifiziersäule beziehungsweise der Hochreinstickstoff-Säule jeweils ein bis fünf, vorzugsweise zwei bis drei so genannte Sperrböden. Die beiden Maßnahmen bewirken jede für sich eine Verminderung des Gehalts an leichter flüchtigen Komponenten im hoch reinen Stickstoff; sie können einzeln oder in Kombination angewendet werden.In many cases, a particularly low concentration is more volatile Impurities such as hydrogen, neon and / or helium in the high purity nitrogen product he wishes. For this purpose, it is advantageous if the cycle nitrogen is at least a theoretical or practical floor below the head of the first rectification column is removed and / or the high purity nitrogen at least a theoretical or practical floor below the head of the High purity nitrogen column is removed. Preferably located on the head first rectification column or the high-purity nitrogen column one to five, preferably two to three so-called barrier floors. The two measures each cause a reduction in the more volatile content Components in high purity nitrogen; they can be used individually or in combination be applied.

    Es ist ferner günstig, wenn Rücklauf für die Hochreinstickstoff-Säule in einem Kopfkondensator erzeugt wird, indem ein zweiter Teilstrom des verflüssigten Kreislauf-Stickstoffs in einem Kopfkondensator der Hochreinstickstoff-Säule gegen kondensierendes Kopfgas der Hochreinstickstoff-Säule verdampft wird. Der im Kopfkondensator der Hochreinstickstoff-Säule verdampfte Kreislauf-Stickstoff wird vorzugsweise zum Kreislaufverdichter zurückgeführt, beispielsweise indem er mit dem von der ersten Rektifiziersäule kommenden Kreislauf-Stickstoff vermischt wird. Mit einer derartigen Verfahrensführung wird auch die zum Betrieb der Hochreinstickstoff-Säule erforderliche Verfahrenskälte von dem Stickstoff-Kreislauf geliefert. Im Verdampfungsraum des Kopfkondensators muss dazu ein geringfügig geringerer Druck herrschen als im Kopf der Hochreinstickstoff-Säule, damit die entsprechende Temperaturdifferenz den Wärmeübergang am Kopfkondensator antreiben kann. Der Betriebsdruck am Kopf der Hochreinstickstoff-Säule ist beispielsweise gleich dem Druck am Kopf der ersten Rektifiziersäule.It is also beneficial if return for the high-purity nitrogen column in one Top condenser is generated by a second substream of the liquefied cycle nitrogen against the high-purity nitrogen column in a top condenser condensing head gas of the high-purity nitrogen column is evaporated. The one in Head condenser of the high-purity nitrogen column is evaporated cycle nitrogen preferably returned to the circuit compressor, for example by using the circulating nitrogen coming from the first rectification column is mixed. With Such a procedure is also used to operate the high-purity nitrogen column required process cold supplied by the nitrogen cycle. in the Evaporation space of the top condenser has to be slightly smaller There is pressure than in the head of the high-purity nitrogen column, so the corresponding Temperature difference can drive the heat transfer at the top condenser. The Operating pressure at the top of the high-purity nitrogen column is, for example, the same Pressure at the head of the first rectification column.

    Der zweite Teilstrom des verflüssigten Kreislauf-Stickstoffs kann dazu direkt aus dem Kreislauf zum Verdampfungsraum des Kopfkondensators der Hochreinstickstoff-Säule geführt werden. Vorzugsweise wird er jedoch zunächst in die Hochreinstickstoff-Säule eingeleitet, aus dem unteren Bereich der Hochreinstickstoff-Säule abgezogen und anschließend der Verdampfung im Kopfkondensator der Hochreinstickstoff-Säule zugeleitet.The second partial stream of the liquefied cycle nitrogen can be directly from the Circuit to the evaporation chamber of the top condenser of the high-purity nitrogen column be performed. However, it is preferably first placed in the high-purity nitrogen column initiated, withdrawn from the lower area of the high-purity nitrogen column and then the evaporation in the top condenser of the high-purity nitrogen column fed.

    Auch der erste Teilstrom des verflüssigten Kreislauf-Stickstoffs kann in die Hochreinstickstoff-Säule eingeleitet werden - beispielsweise gemeinsam mit dem zweiten Teilstrom. Er wird dann ebenso aus dem unteren Bereich der Hochreinstickstoff-Säule abgezogen und anschließend in das Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung zurückgeleitet.The first partial stream of the liquefied cycle nitrogen can also flow into the High purity nitrogen column can be initiated - for example, together with the second partial flow. He will then also be from the bottom of the High-purity nitrogen column pulled off and then into the rectification system Nitrogen-oxygen separation returned.

    Der verflüssigte Kreislauf-Stickstoff (erster Teil des verdichteten Kreislauf-Stickstoffs) muss stromaufwärts seiner Aufteilung in den ersten und zweiten Teilstrom beziehungsweise seiner Einleitung in die erste Rektifiziersäule entspannt werden. Dieser Entspannungsschritt kann mittels eines Drosselventils vorgenommen werden. Bei dem erfindungsgemäßen Verfahren ist es günstig, wenn er arbeitsleistend durchgeführt wird. Dazu tritt der entsprechende Teilstrom des Kreislauf-Stickstoffs beispielsweise in überkritischem Zustand in eine Turbine ein und wird darin ohne Phasenübergang auf einen unterkritischen Druck entspannt, so dass er vollständig flüssig oder in Wesentlichen vollständig flüssig (Gasanteil beispielsweise bis zu etwa 5 %) aus der Turbine austritt. Alternativ ist auch eine Beschickung der Turbine mit bereits flüssigem Kreislauf-Stickstoff unter unterkritischem Druck möglich. Vorzugsweise werden der erste und der zweite Teilstrom des ersten Teils des Kreislauf-Stickstoffs gemeinsam arbeitsleistend entspannt, anschließend gemeinsam in die Hochreinstickstoff-Säule eingeleitet; stromabwärts der Hochreinstickstoff-Säule findet dann die Aufteilung in den ersten und zweiten Teilstrom statt.The liquefied cycle nitrogen (first part of the compressed cycle nitrogen) must be upstream of its division into the first and second substreams or its introduction into the first rectification column can be relaxed. This expansion step can be carried out using a throttle valve. In the method according to the invention, it is advantageous if it does work is carried out. In addition there is the corresponding partial flow of the cycle nitrogen for example in a supercritical state in a turbine and is without it Phase transition relaxes to a subcritical pressure, making it complete liquid or essentially completely liquid (gas content, for example, up to about 5%) emerges from the turbine. Alternatively, the turbine can also be charged already liquid circulating nitrogen possible under subcritical pressure. Preferably, the first and the second partial stream of the first part of the Cycle nitrogen relaxed together to perform work, then together in the high-purity nitrogen column initiated; downstream of the high purity nitrogen column the division into the first and second partial stream then takes place.

    Vorzugsweise wird ein Zwei-Turbinen-Kreislauf eingesetzt, bei dem ein dritter Teil des verdichteten Kreislauf-Stickstoffs arbeitsleistend entspannt und mindestens teilweise zum Kreislaufverdichter zurückgeführt wird, wobei die Eintrittstemperatur der arbeitsleistenden Entspannung des dritten Teils des verdichteten Kreislauf-Stickstoffs höher als Eintrittstemperatur der arbeitsleistenden Entspannung des zweiten Teils des verdichteten Kreislauf-Stickstoffs ist. Diejenige Fraktion, die in der Hochreinstickstoff-Säule weiter aufgearbeitet wird, durchströmt also die kalte Turbine. Der dritte Teilstrom wird nach der arbeitsleistenden Entspannung vorzugsweise zum Eintritt des Kreislaufverdichters zurückgeführt, beispielsweise gemeinsam mit dem Kreislauf-Stickstoff aus der ersten Rektifiziersäule.A two-turbine circuit is preferably used, in which a third part of the compressed cycle nitrogen relieved work and at least partially is returned to the circuit compressor, the inlet temperature of the work-relieving relaxation of the third part of the compressed cycle nitrogen higher than the inlet temperature of the work relaxation of the second part of the compressed cycle nitrogen. The fraction in the high-purity nitrogen column is worked up further, flows through the cold turbine. The third sub-stream is preferably after the work-related relaxation at the entry of the Recycle compressor returned, for example, together with the cycle nitrogen from the first rectification column.

    Grundsätzlich ist es auch möglich, den Stickstoff aus der warmen Turbine oder aus beiden Turbinen in die Hochreinstickstoff-Säule einzuleiten.Basically, it is also possible to get the nitrogen out of the warm turbine or out two turbines into the high-purity nitrogen column.

    Dabei ist es günstig, wenn der Austrittsdruck der arbeitsleistenden Entspannung des dritten Teils des verdichteten Kreislauf-Stickstoffs niedriger als der Austrittsdruck der arbeitsleistenden Entspannung des zweiten Teils des verdichteten Kreislauf-Stickstoffs ist. Diese Betriebsweise ermöglicht einerseits einen besonders effizienten Betrieb der beiden Turbinen, in denen gasförmiger Kreislauf-Stickstoff entspannt wird; andererseits wird der höhere Druck des zweiten Teils zum Betrieb der Hochreinstickstoff-Säule ausgenützt.It is advantageous if the outlet pressure of the work-related relaxation of the third part of the compressed cycle nitrogen lower than the outlet pressure of the work-relieving relaxation of the second part of the compressed cycle nitrogen is. On the one hand, this mode of operation enables particularly efficient operation of the two turbines in which gaseous nitrogen is expanded; on the other hand becomes the higher pressure of the second part to operate the high-purity nitrogen column exploited.

    Bei der Erfindung herrschen in den verschiedenen Verfahrensschritten beispielsweise folgende Drücke und Temperaturen:

  • Betriebsdruck der ersten Rektifiziersäule (z. B. Hochdruckteil einer Doppelsäule) am Kopf:
  • beispielsweise 5 bis 12 bar, vorzugsweise 6 bis 8 bar
    Austrittsdruck des Kreislaufverdichters:
  • beispielsweise 22 bis 63 bar, vorzugsweise 28 bis 37 bar
    Eintrittsdruck der kalten Turbine (zweiter Teil des verdichteten Kreislauf-Stickstoffs):
  • beispielsweise 50 bis 70 bar, vorzugsweise 58 bis 63 bar
    Austrittsdruck der kalten Turbine:
  • beispielsweise 4 bis 11 bar, vorzugsweise 6,5 bis 8,5 bar
    Eintrittstemperatur der kalten Turbine:
  • beispielsweise 150 bis 175 K, vorzugsweise 155 bis 170 K
    Eintrittsdruck der warmen Turbine (dritter Teil des verdichteten Kreislauf-Stickstoffs):
  • beispielsweise 22 bis 63 bar, vorzugsweise 28 bis 37 bar
    Austrittsdruck der warmen Turbine:
  • beispielsweise 5 bis 12 bar, vorzugsweise 6 bis 8 bar
    Eintrittstemperatur der warmen Turbine:
  • beispielsweise 250 bis 270 K
    Druck des zu verflüssigenden Kreislauf-Stickstoffs:
  • beispielsweise 50 bis 70 bar, vorzugsweise 35 bis 68 bar
    Betriebsdruck der Hochreinstickstoff-Säule am Kopf:
  • beispielsweise 5 bis 12 bar, vorzugsweise 6,5 bis 8,5 bar
    Druck im Verdampfungsraum des Kopfkondensators der Hochreinstickstoff-Säule:
  • beispielsweise 4,5 bis 11,5 bar, vorzugsweise 6 bis 8 bar
    • In the invention, the following pressures and temperatures prevail in the various process steps:
  • Operating pressure of the first rectification column (e.g. high pressure part of a double column) at the head:
  • for example 5 to 12 bar, preferably 6 to 8 bar
    Outlet pressure of the circuit compressor:
  • for example 22 to 63 bar, preferably 28 to 37 bar
    Inlet pressure of the cold turbine (second part of the compressed cycle nitrogen):
  • for example 50 to 70 bar, preferably 58 to 63 bar
    Cold turbine outlet pressure:
  • for example 4 to 11 bar, preferably 6.5 to 8.5 bar
    Cold turbine inlet temperature:
  • for example 150 to 175 K, preferably 155 to 170 K.
    Inlet pressure of the warm turbine (third part of the compressed cycle nitrogen):
  • for example 22 to 63 bar, preferably 28 to 37 bar
    Outlet pressure of the warm turbine:
  • for example 5 to 12 bar, preferably 6 to 8 bar
    Inlet temperature of the warm turbine:
  • for example 250 to 270 K.
    Circulating nitrogen pressure to be liquefied:
  • for example 50 to 70 bar, preferably 35 to 68 bar
    Operating pressure of the high-purity nitrogen column at the head:
  • for example 5 to 12 bar, preferably 6.5 to 8.5 bar
    Pressure in the evaporation chamber of the top condenser of the high-purity nitrogen column:
  • for example 4.5 to 11.5 bar, preferably 6 to 8 bar

    • Die Erfindung betrifft außerdem eine Vorrichtung zur Erzeugung hoch reinen Stickstoffs durch Tieftemperatur-Luftzerlegung gemäß Patentanspruch 10. The invention also relates to a device for producing high-purity nitrogen by low-temperature air separation according to claim 10.

    Die Erfindung sowie weitere Einzelheiten der Erfindung werden im folgenden anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert.The invention and further details of the invention are described below of an embodiment shown in the drawing.

    Auf einen Druck von 6,5 bar verdichtete und von Wasserdampf und Kohlendioxid gereinigte Luft 1 wird in einem Hauptwärmetauscher 2 auf etwa Taupunkt abgekühlt und über eine Leitung 3 einer Hochdrucksäule 4 zugeleitet, die in dem Beispiel die "erste Rektifiziersäule" darstellt. Die Hochdrucksäule 4 ist Teil des Rektifiziersystems zur Stickstoff-Sauerstoff-Trennung, das hier außerdem eine Niederdrucksäule 5 umfasst. Die beiden Säulen 4 und 5 werden hier unter einem Druck von 6,2 bar beziehungsweise 1,3 bar (jeweils am Kopf) betrieben. Sie stehen über einen Hauptkondensator 6 in wärmetauschender Verbindung. Dort wird Kopfstickstoff 7 der Hochdrucksäule 4 gegen verdampfende Sumpfflüssigkeit der Niederdrucksäule 5 kondensiert; das dabei gebildete Kondensat 8 wird der Hochdrucksäule 4 als Rücklauf aufgegeben.Compressed to a pressure of 6.5 bar and by water vapor and carbon dioxide cleaned air 1 is cooled in a main heat exchanger 2 to about dew point and fed via a line 3 to a high-pressure column 4, which in the example is the represents "first rectification column". The high pressure column 4 is part of the rectification system for nitrogen-oxygen separation, which is also a low-pressure column 5 includes. The two columns 4 and 5 are here under a pressure of 6.2 bar or 1.3 bar (each at the head) operated. You are above one Main condenser 6 in heat-exchanging connection. There is 7 nitrogen High pressure column 4 against evaporating sump liquid of the low pressure column 5 condensed; the condensate 8 thus formed is the high pressure column 4 as a return given up.

    Über Leitung 18 wird flüssiger Stickstoff aus der Hochdrucksäule 4 abgeführt, und zwar zwei Böden 76 unterhalb des Kopfs. (Diese Sperrböden dienen zur Zurückhaltung von leichter flüchtigen Verunreinigungen, die als nicht kondensierbares Gas über einen nicht dargestellten Ablass am Hauptkondensator abgezogen werden können.) Der flüssige Stickstoff 18 wird in einem Unterkühlungs-Gegenströmer 10 unterkühlt, mittels eines Drosselventils 19 auf knapp über Niederdrucksäulendruck entspannt und in einen Abscheider 20 eingeleitet. Flashgas 21 aus dem Abscheider wird dem Kopfstickstoff 14 zugemischt. Über Leitung 22 wird Flüssigkeit aus dem Abscheider 20 der Niederdrucksäule als Rücklauf zugeführt. Falls gewünscht, kann hier außerdem über Leitung 23 ein Flüssigprodukt (LIN) abgezogen werden.Liquid nitrogen is discharged from the high-pressure column 4 via line 18, specifically two bottoms 76 below the head. (These plywood floors are used to hold back more volatile impurities that are present as a non-condensable gas Drain not shown on the main condenser can be deducted.) The liquid nitrogen 18 is subcooled in a subcooling countercurrent 10, by means of a throttle valve 19 relaxed to just above low pressure column pressure and in a separator 20 initiated. Flash gas 21 from the separator is the Head nitrogen 14 mixed. Liquid is removed from the separator 20 via line 22 fed to the low pressure column as a return. If desired, you can also here A liquid product (LIN) is drawn off via line 23.

    Die Sauerstoff-angereicherte Sumpfflüssigkeit 9 wird im Unterkühlungs-Gegenströmer 10 unterkühlt und über ein Drosselventil 11 in die Niederdrucksäule 5 eingeführt. Vom Sumpf der Niederdrucksäule 5 wird flüssiger Sauerstoff 12 abgezogen und - gegebenenfalls nach Unterkühlung im Unterkühlungs-Gegenströmer 10 über Leitung 13 als Flüssigprodukt (LOX) abgezogen. (Alternativ oder zusätzlich kann gasförmiger Sauerstoff aus dem unteren Bereich der Niederdrucksäule 5 abgeführt werden.) Als Kopfprodukt der Niederdrucksäule 5 wird gasförmiger Stickstoff 14 gewöhnlicher Reinheit entnommen, der in dem Beispiel noch 150 ppm an schwerer flüchtigen Komponenten, insbesondere Argon und CO enthält. Über die Leitungen 15, 16, 17 wird Unrein-Stickstoff aus der Niederdrucksäule 5 im Unterkühlungs-Gegenströmer 10 und im Hauptwärmetauscher 2 angewärmt und gegebenenfalls als Regeneriergas für eine nicht dargestellte Vorrichtung zur Luftreinigung eingesetzt.The oxygen-enriched bottom liquid 9 is in the supercooling counterflow 10 supercooled and introduced into the low-pressure column 5 via a throttle valve 11. from Bottom of the low pressure column 5, liquid oxygen 12 is drawn off and if necessary after subcooling in the subcooling countercurrent 10 via line 13 deducted as a liquid product (LOX). (Alternatively or additionally, it can be gaseous Oxygen can be removed from the lower region of the low-pressure column 5.) As Top product of the low pressure column 5 becomes more gaseous nitrogen 14 Purity taken from that in the example 150 ppm of less volatile Contains components, especially argon and CO. Via lines 15, 16, 17 Impure nitrogen from the low pressure column 5 in the supercooling counterflow 10 and warmed in the main heat exchanger 2 and optionally as a regeneration gas for one Not shown device used for air purification.

    Die Hochdrucksäule 4 ist mit einem Stickstoff-Kreislauf verbunden. Hierzu wird Kreislauf-Stickstoff 24 gasförmig dem oberen Bereich der ersten Rektifiziersäule (Hochdrucksäule) 4 entnommen. (Seine Zusammensetzung ist praktisch gleich derjenigen des Kopfstickstoffs 14 der Niederdrucksäule.) Die Entnahme erfolgt in dem Beispiel an derselben Zwischenstelle, an der auch der flüssige Stickstoff 18 für die Niederdrucksäule entnommen wird, nämlich unterhalb der Sperrböden 76. (Auf die Sperrböden 76 kann auch verzichtet werden; in diesem Fall erfolgt die Entnahme des Kreislauf-Stickstoffs aus der ersten Rektifiziersäule an deren Kopf.) Mindestens ein Teil 25 des gasförmigen Kreislauf-Stickstoffs wird im Hauptwärmetauscher 2 auf etwa Umgebungstemperatur angewärmt und über die Leitungen 26, 27, 28, 29 dem Eintritt eines Kreislaufverdichters 30 zugeführt, wo er auf etwa 30 bar komprimiert wird.The high pressure column 4 is connected to a nitrogen cycle. To do this Circulating nitrogen 24 in gaseous form in the upper region of the first rectification column (High pressure column) 4 removed. (Its composition is practically the same that of the top nitrogen 14 of the low pressure column.) The removal takes place in the Example at the same intermediate point at which the liquid nitrogen 18 for the Low pressure column is removed, namely below the blocking floors 76. (On the Barrier floors 76 can also be dispensed with; in this case the Circulating nitrogen from the first rectification column at the top.) At least a part 25 of the gaseous cycle nitrogen is in the main heat exchanger 2 to about Ambient temperature warmed and via the lines 26, 27, 28, 29 the entrance a circuit compressor 30 supplied, where it is compressed to about 30 bar.

    Nach Entfernung der Verdichtungswärme in einem Nachkühler 31 wird ein erster Teil des im Kreislaufverdichter 30 verdichteten Kreislauf-Stickstoffs über Leitung 43 nacheinander durch die Nachverdichter 44, 46 (jeweils gefolgt von einem Nachkühler 45, 47) geführt, dort auf einen Druck von 60 bar gebracht und über die Leitung 33 in einen ersten Kreislauf-Wärmetauscher 34a eingeführt, der zusammen mit einem zweiten, teilweise parallel geschalteten Kreislauf-Wärmetauscher 34b ein Kreislauf-Wärmetauscher-System bildet. Vom kalten Ende des ersten Kreislauf-Wärmetauschers 34a aus tritt der abgekühlte erste Teil 35 des verdichteten Kreislauf-Stickstoffs in überkritischem Zustand in eine Flüssigturbine 36 ein und wird dort arbeitsleistend auf 6,5 bar entspannt. Die Flüssigturbine 36 ist mit einer mechanischen Bremsvorrichtung 37 verbunden, beispielsweise mit einem Generator oder einer Ölbremse.After removal of the heat of compression in an aftercooler 31, a first part of the cycle nitrogen compressed in the cycle compressor 30 via line 43 successively through the post-compressors 44, 46 (each followed by an after-cooler 45, 47), brought there to a pressure of 60 bar and via line 33 in introduced a first circuit heat exchanger 34a, which together with a second, partially connected circuit heat exchanger 34b, a circuit heat exchanger system forms. From the cold end of the first cycle heat exchanger 34a, the cooled first part 35 of the compressed cycle nitrogen enters supercritical state in a liquid turbine 36 and is there to perform work 6.5 bar relaxed. The liquid turbine 36 is equipped with a mechanical braking device 37 connected, for example with a generator or an oil brake.

    Der entspannte erste Teil 38 des Kreislauf-Stickstoffs befindet sich nun im flüssigen Zustand und wird in eine Hochreinstickstoff-Säule 39 eingespeist, und zwar einen oder mehrere Böden oberhalb deren Sumpfs (oder auch unmittelbar über dem Sumpf der Hochreinstickstoff-Säule). Er wird über Leitung 40 sofort wieder entnommen. Ein erster Teilstrom 42 wird wieder in die Hochdrucksäule 4 zurückgespeist, womit sich der Stickstoff-Kreislauf schließt. Falls notwendig, kann eine Pumpe 41 zur Förderung des verflüssigten ersten Teils 40 des Kreislauf-Stickstoffs eingesetzt werden.The relaxed first part 38 of the cycle nitrogen is now in the liquid State and is fed into a high purity nitrogen column 39, one or several soils above their swamps (or just above the swamp of the High purity nitrogen column). It is immediately removed again via line 40. A first one Partial stream 42 is fed back into the high-pressure column 4, whereby the Nitrogen cycle closes. If necessary, a pump 41 to promote the liquefied first part 40 of the cycle nitrogen are used.

    Ein zweiter Teil des im Kreislaufverdichter 30 verdichteten Kreislauf-Stickstoffs wird über die Leitungen 43 und 48 gemeinsam mit dem ersten Teil durch die Nachverdichter 44 und 46 geführt und wird dann in zwei Zweigströmen (durch Leitungen 33 - 50a beziehungsweise 49 - 50b) im Kreislauf-Wärmetauscher-System 34a, 34b auf etwa 170 K abgekühlt. Bei dieser Zwischentemperatur, die höher als die Temperatur des kalten Endes liegt, wird der zweite Teil des Kreislauf-Stickstoffs über die Leitungen 50a und 50b zu einer kalten Turbine 51 geleitet und dort arbeitsleistend auf etwa 6,5 bar entspannt. Der entspannte zweite Teil 52 des Kreislauf-Stickstoffs dient als gasförmiger Einsatz für die Hochreinstickstoff-Säule 39 und wird unmittelbar oberhalb des Sumpfs eingespeist. Er bildet den in der Hochreinstickstoff-Säule 39 aufsteigenden Dampf.A second part of the cycle nitrogen compressed in the cycle compressor 30 is via lines 43 and 48 together with the first part through the booster 44 and 46 and is then in two branch flows (through lines 33 - 50a or 49 - 50b) in the circuit heat exchanger system 34a, 34b to about Cooled down to 170 K. At this intermediate temperature, which is higher than the temperature of the cold end, the second part of the cycle nitrogen via the lines 50a and 50b to a cold turbine 51 and there to work at about 6.5 bar relaxed. The relaxed second part 52 of the cycle nitrogen serves as gaseous use for the high-purity nitrogen column 39 and is immediately above fed into the swamp. It forms the ascending in the high-purity nitrogen column 39 Steam.

    Durch den Gegenstrom innerhalb der Hochreinstickstoff-Säule 39 werden schwerer flüchtige Bestandteile wie zum Beispiel CO und/oder Argon aus dem gasförmigen Stickstoff ausgewaschen. Das Kopfgas 53 der Hochreinstickstoff-Säule 39 wird in einem Kopfkondensator 54 praktisch vollständig kondensiert (bis auf einen nicht dargestellten Ablass für leichter flüchtige Bestandteile). Das Kondensat 55 fließt als Rücklauf zurück in die Hochreinstickstoff-Säule 39. Der Kopfkondensator 54 wird durch einen Teilstrom 67 des verflüssigten ersten Teils 40 des Kreislauf-Stickstoffs gekühlt. Der dabei gebildete Dampf 68 wird im ersten Kreislauf-Wärmetauscher 34 angewärmt und über die Leitungen 69, 28 und 29 zum Eintritt des Kreislaufverdichters 30 zurückgeführt. Die beiden Kreislauf-Wärmetauscher 34a, 34b könne auch als ein gemeinsamer Block ausgeführt sein (nicht dargestellt).The countercurrent within the high-purity nitrogen column 39 makes it heavier volatile components such as CO and / or argon from the gaseous Washed out nitrogen. The top gas 53 of the high-purity nitrogen column 39 is in a top condenser 54 is practically completely condensed (except for one shown discharge for more volatile components). The condensate 55 flows as Return back to the high-purity nitrogen column 39. The top condenser 54 is through cooled a partial flow 67 of the liquefied first part 40 of the cycle nitrogen. The steam 68 formed in the process is heated in the first circuit heat exchanger 34 and via lines 69, 28 and 29 to the inlet of the circuit compressor 30 recycled. The two circuit heat exchangers 34a, 34b can also be used as one shared block (not shown).

    Über Leitung 56 wird hoch reiner Stickstoff flüssig abgezogen. Zur Rückhaltung von leichter flüchtigen Komponenten dienen zwei bis drei Sperrböden 57 oberhalb der Produktentnahme. Der flüssige hoch reine Stickstoff 56 strömt weiter über Leitung 57 zum Unterkühlungs-Gegenströmer 10. Der unterkühlte hoch reine Stickstoff 58 wird in einem Drosselventil 59 auf 1,4 bar entspannt und in einen Abscheider 60 eingeleitet. Flashgas 61 aus dem Abscheider 60 wird dem Kopfstickstoff 14 der Niederdrucksäule 5 zugemischt. Über Leitung 62 wird die Flüssigkeit aus dem Abscheider 60 als hoch reines Stickstoffprodukt (HLIN) abgezogen. Highly pure nitrogen is withdrawn in liquid form via line 56. To withhold more volatile components serve two to three blocking floors 57 above the Product withdrawal. The liquid, highly pure nitrogen 56 continues to flow via line 57 to the supercooling counterflow 10. The supercooled high-purity nitrogen 58 is in a throttle valve 59 relaxed to 1.4 bar and introduced into a separator 60. Flash gas 61 from the separator 60 becomes the top nitrogen 14 of the low pressure column 5 added. The liquid from the separator 60 is high via line 62 pure nitrogen product (HLIN) deducted.

    Der Stickstoff-Kreislauf wird außerdem vom Kopfstickstoff 14 der Niederdrucksäule 5 gespeist, der nach Anwärmung im Unterkühlungs-Gegenströmer 10 und im Hauptwärmetauscher 2 über Leitung 63 einem Feedgas-Verdichter 64 zugeleitet wird. Nach Verdichtung auf etwa den Eintrittsdruck des Kreislaufverdichters 30 und Nachkühlung 65 strömt er über die Leitungen 66 und 29 zum Kreislaufverdichter.The nitrogen cycle is also from the top nitrogen 14 of the low pressure column 5th fed, which after heating in the supercooling counterflow 10 and in Main heat exchanger 2 is fed via line 63 to a feed gas compressor 64. After compression to about the inlet pressure of the circuit compressor 30 and Aftercooling 65 it flows via lines 66 and 29 to the circuit compressor.

    Ein dritter Teil 70 des im Kreislauf-Verdichter 30 verdichteten Kreislauf-Stickstoffs wird in zwei Zweigen 71a-72a beziehungsweise 71b - 72b im Kreislauf-Wärmetauscher-System 34a, 34b auf etwa 260 K abgekühlt. Unter dieser Temperatur tritt er über Leitung 72 in eine warme Turbine 73 ein und wird darin arbeitsleistend auf etwa 6 bar entspannt. Der entspannte dritte Teil des Kreislauf-Stickstoffs wird über die Leitungen 74a und 74b wieder zum Kreislauf-Wärmetauscher-System 34a, 34b geführt und strömt nach seiner Anwärmung zurück zum Kreislaufverdichter 30.A third part 70 of the cycle nitrogen compressed in the cycle compressor 30 becomes in two branches 71a-72a and 71b - 72b in the cycle heat exchanger system 34a, 34b cooled to about 260 K. At this temperature it passes over Line 72 into a warm turbine 73 and is working there to about 6 bar relaxed. The relaxed third part of the cycle nitrogen is via the lines 74a and 74b again to the circuit heat exchanger system 34a, 34b and flows back to the circuit compressor 30 after it has warmed up.

    Die mechanische Energie, die in den beiden gasförmig beaufschlagten Turbinen 51, 73 erzeugt wird, dient zum Antrieb der Nachverdichter 44, 46. Vorzugsweise sind die Turbinen und Nachverdichter unmittelbar mechanisch gekoppelt. Alternativ können die Turbinen 51, 73 durch Generatoren gebremst werden; in diesem Fall wird der gesamte Kreislauf-Stickstoff ausschließlich im Kreislaufverdichter 30 komprimiert (nicht dargestellt).The mechanical energy generated in the two gaseous turbines 51, 73 is generated, is used to drive the post-compressor 44, 46. These are preferably Turbines and post-compressors are directly mechanically coupled. Alternatively, the Turbines 51, 73 are braked by generators; in this case the whole Recycle nitrogen is only compressed in the recycle compressor 30 (not ) Shown.

    Ausgleichsströme 76, 77 dient zur Optimierung des Wärmeübergangs in den drei Wärmetauscher-Blöcken 34a, 34b.Equalizing currents 76, 77 serve to optimize the heat transfer in the three Heat exchanger blocks 34a, 34b.

    Das erfindungsgemäße Verfahren kann gegenüber dem Ausführungsbeispiel in vielfältiger Weise variiert werden.The method according to the invention can be compared to the exemplary embodiment in can be varied in many ways.

    So ist es möglich, den gasförmigen Einsatz für die Hochreinstickstoff-Säule (Leitung 52 in der Zeichnung) stromaufwärts des Kreislaufverdichters abzunehmen, beispielsweise am Austritt des Nachkühlers 65 des Feedgas-Verdichters 64.It is thus possible to use the gaseous insert for the high-purity nitrogen column (line 52 decrease in the drawing) upstream of the circuit compressor, for example at the outlet of the aftercooler 65 of the feed gas compressor 64.

    An Stelle der Einleitung der Flüssigkeit 38 aus dem Kreislauf in die Hochreinstickstoff-Säule 39 kann diese Flüssigkeit auch mindestens teilweise direkt in den Verdampfungsraum des Kopfkondensators 54 der Hochreinstickstoff-Säule oder in die Hochdrucksäule 4 eingeleitet werden. Im letzteren Fall müsste das Kältemittel für den Kopfkondensator 54 von der Hochdrucksäule 4 abgenommen werden.Instead of introducing the liquid 38 from the circuit into the high-purity nitrogen column 39, this liquid can also be at least partially directly in the Evaporation space of the top condenser 54 of the high-purity nitrogen column or in the High pressure column 4 are initiated. In the latter case, the refrigerant for the Top condenser 54 can be removed from the high pressure column 4.

    Insbesondere bei Anlagen, in denen kein flüssiger Sauerstoff gewonnen werden soll, kann auf die Zuführung von Niederdrucksäulen-Stickstoff 63 zum Kreislauf und damit auf den Feedgas-Verdichter 64 verzichtet werden. Es kann in solchen Fällen sinnvoll sein, die Doppelsäule 4/5 unter erhöhtem Druck zu betrieben und die Niederdrucksäule 5 mit einem Kopfkondensator auszustatten, wie es beispielsweise in DE 3528374 A1 gezeigt ist.Especially in plants in which no liquid oxygen is to be obtained, can on the supply of low pressure column nitrogen 63 to the circuit and thus the feed gas compressor 64 can be dispensed with. It can be useful in such cases be to operate the double column 4/5 under increased pressure and the low pressure column 5 to be equipped with a top capacitor, as is the case, for example, in DE 3528374 A1 is shown.

    Claims (13)

    1. Process for generating high-purity nitrogen by low-temperature fractionation of air in a rectification system for nitrogen/oxygen separation, which has at least a first rectifier column (4), in which process
      a. cycle nitrogen (24) in gas form is removed from the upper region of the first rectifier column (4), and
      b. is compressed in a cycle compressor (30),
      c. a first part (35) of the compressed cycle nitrogen is liquefied,
      d. a nitrogen fraction (52) from the rectifier system for nitrogen/oxygen separation is introduced (52) into a high-purity nitrogen column (39) which has a top condenser (54), and
      e. high-purity nitrogen (56) is removed from the upper region of the high-purity nitrogen column (39), characterized in that
      f. the refrigeration demand of the top condenser (54) of the high-purity nitrogen column (39) is at least partially covered by liquefied cycle nitrogen (38).
    2. Process according to Claim 1, characterized in that at least a first part-stream (42) of the liquefied cycle nitrogen (38, 40) is fed back into the rectification system for nitrogen/oxygen separation, in particular into the first rectifier column (4).
    3. Process according to Claim 1 or 2, characterized in that a second part of the compressed cycle nitrogen is expanded (51) and introduced (52) into the high-purity nitrogen (39).
    4. Process according to Claim 3, characterized in that the expansion (51) of the second part of the compressed cycle nitrogen is carried out in a work-performing manner.
    5. Process according to one of Claims 1 to 4, in which
      the cycle nitrogen (24) is removed at least one theoretical practical plate (76) below the top of the first rectifier column,
      and/or
      the high-purity nitrogen (56) is removed at least one theoretical or practical plate (78) below the top of the high-purity nitrogen column (39).
    6. Process according to one of Claims 1 to 5, in which a second part-stream (67) of the liquefied cycle nitrogen (38, 40) is evaporated against condensing top gas (53) from the high-purity nitrogen column (39) in a top condenser (54) of the high-purity nitrogen column (39).
    7. Process according to Claim 6, in which the cycle nitrogen (68) which is evaporated in the top condenser (54) of the high-purity nitrogen column (39) is returned to the cycle compressor (30).
    8. Process according to one of Claims 6 or 7, in which the second part-stream of the liquefied cycle nitrogen is introduced (38) into the high-purity nitrogen column (39), is tapped off (40) from the lower region of the high-purity nitrogen column, and is then fed (67) for evaporation in the top condenser (54) of the high-purity nitrogen column.
    9. Process according to one of Claims 2 to 8, in which the first part-stream of the liquefied cycle nitrogen is introduced (38) into the high-purity nitrogen column (39), is tapped off (40) from the lower region of the high-purity nitrogen column, and is then fed back (42) into the rectification system for nitrogen/oxygen separation.
    10. Process according to one of Claims 3, 4, 5 (in so far as it refers back to Claim 3 or 4) or 6 to 9, in which the first part (35) of the cycle nitrogen is expanded (36) in a work-performing manner upstream of the point where it is divided into the first and second part-streams.
    11. Process according to one of Claims 4, 5 (in so far as it refers back to Claim 4) or 6 to 10, in which a third part of the compressed cycle nitrogen (72a, 72b) is expanded (73) in a work-performing manner and is at least partially returned to the cycle compressor (30), the entry temperature of the work-performing expansion (73) of the third part of the compressed cycle nitrogen being higher than the entry temperature of the work-performing expansion (51) of the second part of the compressed cycle nitrogen.
    12. Process according to Claim 11, in which the exit pressure of the work-performing expansion (72) of the third part of the compressed cycle nitrogen is lower than the exit pressure of the work-performing expansion (51) of the second part of the compressed cycle nitrogen.
    13. Apparatus for generating high-purity nitrogen by low-temperature fractionation of air, having a rectification system for nitrogen/oxygen separation which has at least a first rectifier column (4),
      having a cycle line (24, 25, 26, 27, 28, 29) for feeding gaseous cycle nitrogen out of the upper region of the first rectifier column (4) to a cycle compressor (30),
      having means (34a, 36) for liquefying a first part (35) of the compressed cycle nitrogen,
      having means (52) for introducing a nitrogen fraction into a high-purity nitrogen column (39), the high-purity nitrogen column having a top condenser (54), and
      having a product line for removing high-purity nitrogen (56) from the upper region of the high-purity nitrogen column (39),
      characterized by
      means for directly or indirectly introducing at least a part-stream of the liquefied cycle nitrogen into the evaporation space of the top condenser (54) of the high-purity nitrogen column.
    EP00124031A 2000-09-13 2000-11-04 Process and apparatus for the production of high purity nitrogen through cryogenic air separation Expired - Lifetime EP1189001B1 (en)

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    RU2522132C2 (en) * 2012-07-10 2014-07-10 Ооо "Зиф" Air separation method
    US20150168057A1 (en) * 2013-12-17 2015-06-18 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process for producing liquid nitrogen
    CN106247757B (en) * 2016-08-26 2019-09-24 陈正洪 A kind of gas conversion process and system
    JP6900230B2 (en) * 2017-04-19 2021-07-07 レール・リキード−ソシエテ・アノニム・プール・レテュード・エ・レクスプロワタシオン・デ・プロセデ・ジョルジュ・クロード Nitrogen production system for producing nitrogen with different purity and its nitrogen production method

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    US5402647A (en) * 1994-03-25 1995-04-04 Praxair Technology, Inc. Cryogenic rectification system for producing elevated pressure nitrogen
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