EP1102954A1 - Method and device for cryogenic air separation - Google Patents

Method and device for cryogenic air separation

Info

Publication number
EP1102954A1
EP1102954A1 EP99939452A EP99939452A EP1102954A1 EP 1102954 A1 EP1102954 A1 EP 1102954A1 EP 99939452 A EP99939452 A EP 99939452A EP 99939452 A EP99939452 A EP 99939452A EP 1102954 A1 EP1102954 A1 EP 1102954A1
Authority
EP
European Patent Office
Prior art keywords
pressure column
fraction
liquid
column
oxygen
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.)
Granted
Application number
EP99939452A
Other languages
German (de)
French (fr)
Other versions
EP1102954B1 (en
Inventor
Jürgen Voit
Gerhard Pompl
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
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Linde GmbH filed Critical Linde GmbH
Priority to EP99939452A priority Critical patent/EP1102954B1/en
Publication of EP1102954A1 publication Critical patent/EP1102954A1/en
Application granted granted Critical
Publication of EP1102954B1 publication Critical patent/EP1102954B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04854—Safety aspects of operation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
    • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04642—Recovering noble gases from air
    • F25J3/04745—Krypton and/or Xenon
    • 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
    • F25J3/04969—Retrofitting or revamping of an existing air fractionation unit
    • 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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/90—Details relating to column internals, e.g. structured packing, gas or liquid distribution
    • F25J2200/94—Details relating to the withdrawal point
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
    • 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
    • F25J2215/50—Oxygen or special cases, e.g. isotope-mixtures or low purity O2
    • F25J2215/52—Oxygen production with multiple purity O2
    • 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
    • F25J2235/52—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being oxygen enriched compared to air ("crude oxygen")
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S62/00—Refrigeration
    • Y10S62/923—Inert gas
    • Y10S62/925—Xenon or krypton

Definitions

  • the invention relates to a method for low-temperature air, in which compressed and pre-cleaned feed air is introduced into a rectification system for nitrogen-oxygen separation, which has a pressure column, at least part of the compressed and pre-cleaned feed air being fed to the pressure column and an oxygen-enriched one Fraction of the pressure column is removed and fed to another Anlagensch ⁇ tt within the rectification system
  • the rectification system for nitrogen-oxygen separation can be a single column system with a single column, the pressure suction in the sense of Invention to deal with a two-column system with a pressure column and a low-pressure column or a multi-column system with further separation columns for nitrogen-oxygen separation
  • Several examples of single column systems are shown in Hausen / Linde (page 282, picture 4 1 and 4 2, page 287, picture 4 4, pages 329/330, picture 4 30, 4 31 and 4 32), the invention is particularly applicable to a single column with head cooling by means of an oxygen-enriched liquid from the pressure column (Hausen / Linde, page 330, picture 4 31)
  • two-column systems can be found in Hausen / Linde (page 284, picture 4 3 and various examples in sections 4 5 1 and 4 5 2) For the generation of ascending D Ampf for the low-pressure column
  • the rectification system for nitrogen-oxygen separation in the sense of the invention also comprises heat exchangers such as condenser evaporators which are required for the operation of the separation column (s) for nitrogen-oxygen separation (In particular the main capacitor of a double column or the top capacitor of a single column)
  • the method and the corresponding device according to the invention can, if necessary, have additional separation columns for the extraction of further air components, for example noble gases such as argon helium neon krypton or xenon, outside the rectification system for nitrogen-oxygen separation (see Hausen / Linde, Chapter 4 5 4)
  • the oxygen-enriched fraction is usually removed from the sump area of the pressure column before it is fed to a further work step within the rectification system.
  • This further work step can be formed, for example, by further separation in the low-pressure column of a double-column system or by evaporation, for example in the top condenser of a single-column system All heavier impurities in the feed air, which were not removed in the pre-cleaning upstream of the introduction into the rectification system, are further transported with the oxygen-enriched fraction in the subsequent work steps ("heavily contaminated contaminants" are components of the feed air whose boiling point is higher than that of oxygen )
  • such less volatile impurities can accumulate further.
  • Some of these less volatile substances, in particular N 2 O, can precipitate out as solids and must be removed from time to time so that the heat exchanger passage in the corresponding evaporators (for example in the main condenser of a double column system) is not blocked
  • the entire plant must be switched off. In a large air separation plant, this can mean a shutdown of, for example, two to five days.
  • the entire oxygen-enriched fraction (in the case of a double column, the bottom liquid of the pressure column) is passed in liquid form via an adsorber to remove N 2 0 (liquid adsorbers used to be used at the same point for acetylene removal) This procedure triggers the operational engineering
  • the coil fraction drawn off in the bottom of the pressure column from the method in which it is discarded, possibly after recovery of part of its cold.
  • the coil fraction can, for example, be in a liquid state can be discarded immediately after being discharged from the pressure column, for example into the atmosphere via an ejector Alternatively, it can be evaporated and / or warmed by indirect heat exchange with a heating medium and then discarded in the gaseous state.This recovers part of the energy contained in the coil fraction in the form of cold. The evaporation should take place at such a high temperature that a failure of more volatile
  • Contamination is avoided, for example by introducing the liquid coil fraction into a residual gas fraction at medium temperature.
  • Another possibility is to recover the cold in a heat exchanger with switchable passages (Revex) .All these methods can be useful in certain systems, but have the disadvantage that the Separation work performed on the winding fraction is lost and there is thus a high level of operational expenditure in the form of additional energy requirements
  • the invention is therefore based on the object of designing a method of the type mentioned at the beginning and a corresponding device in such a way that the outlay in terms of operating technology can be kept particularly low in the entire process
  • the winding fraction which is formed by at least part, preferably all, of the bottom liquid of the pressure column, is fed to a device for removing N 2 O without prior evaporation
  • the purified coil fraction downstream of this device can be fed to further workstations inside or outside the rectification system for nitrogen-oxygen separation without there being any risk of N 2 0 accumulation in the course of this workstep.
  • the further workstep can, for example, be a column for nitrogen-oxygen separation or have a condenser-evaporator for generating reflux for such a column, such as the low-pressure column of a two-column system for nitrogen-oxygen separation or the top condenser of the pressure column
  • the mass transfer section between the point at which the feed air is supplied (usually at the bottom of the pressure column) and the removal of the oxygen-enriched fraction enables a largely complete washing out of the less volatile Contamination, in particular of N 2 0, from the feed air into the sump of the pressure column. It is formed either by at least one practical base or by a packing section with a separation effect from at least one theoretical base.
  • the pressure column can be implemented as a single container. Alternatively, different sections can be enclosed by separate containers
  • Mass transfer section which serves to wash out N 2 0, be constructed separately from the rest of the pressure column (see device according to claim 11)
  • the oxygen-enriched fraction contains, for example, less than 1 ppb N 2 O (molar concentration less than 10 "9 ), preferably the molar N 2 O concentrate at 10 "12 or below
  • the less volatile impurities such as N 2 0 are removed with the liquid coil fraction from the bottom of the pressure column.
  • the coil fraction can be removed continuously or discontinuously.
  • the amount of coil fraction withdrawn is determined by the desired or permitted concentration of less volatile components in the coil fraction. As a rule, it is determined set so that no solids failure occurs in the sump of the pressure column, but under certain circumstances a higher enrichment with solids failure is also possible mol% to 5 mol% of the input air volume (the Information about the amount of reel fraction should be understood as a temporal average of the amount of reel fraction - especially in the case of discontinuous removal.)
  • N 2 0 is removed from the liquid rinsing fraction in the cleaning stage by physical adsorption.
  • the cleaning stage is therefore formed by a liquid adsorber.
  • This liquid adsorber can be made much more compact than the liquid adsorber previously used for acetylene removal, through which the entire oxygen-enriched fraction was passed.
  • the N 2 0 can be precipitated in a specially provided heat exchanger by evaporating the liquid rinsing fraction in the cleaning stage by indirect heat exchange, with N 2 O being precipitated as a solid and / or liquid during evaporation. They can be deposited in the heat exchanger in which the evaporation is carried out. In this case, the evaporation must be carried out discontinuously or in a switchable pair of recuperative or regenerative heat exchangers, so that the deposited solids are removed at certain time intervals. However, it is also possible to continuously withdraw any liquid or solids and the cleaned rinsing fraction.
  • Another possibility is to remove N 2 0 in the purification stage by countercurrent mass transfer from the rinsing fraction.
  • the rinsing fraction in the liquid state is introduced into an additional separation column, for example at an intermediate point or on the head.
  • the bottom fraction of the separation column is discarded, for example, while the top fraction is processed further, for example in the pressure column.
  • Heat must be supplied to the bottom of the separation column, for example by indirect heat exchange with a hot current (transfer of sensible heat) or with a condensing gas stream of suitable composition by means of an electrically operated heater.
  • head cooling is necessary, for example by indirect heat exchange with an evaporating process stream of suitable composition and suitable pressure
  • the cleaning stage has both at least one adsorption bed and at least one switchable pair of heat exchangers
  • the purified winding fraction can at least partially be fed to a working step outside of this rectification system.
  • a system for the rectification of a noble gas for example krypton and / or Xenon
  • a noble gas for example krypton and / or Xenon
  • Examples of such systems can be found in the older German patent application 19823526 7 and in the corresponding applications by the same applicant, as well as in EP 96610 A, EP 222026 A, DE 1667639 A, DE 1122088 B or in Streich et al, extraction of noble gases in Air and ammonia systems, Linde reports from technology and science, 37/1975, 10-14
  • the cleaned coil fraction is preferably at least partially introduced in a liquid state into an exchange column which is used to convert krypton and xenon into an inert gas (nitrogen or argon ) to embed this exchange pillar can also be used with the usual krypto ⁇ - and xenon-containing use, namely
  • the total air that is to say the entire feed air which is broken down in the rectification system
  • the entire feed air is preferably fed into the pressure column at least one theoretical or practical base below the point at which the oxygen-enriched fraction is drawn off It is thus avoided that a direct feed of air into further working sections within the rectification system (for example via an air turbine which leads into the low pressure column of a two column system) undesirable less volatile impurities get into an aerodynamic downstream of the pressure column
  • process cold is generated by work-relieving relaxation of an intermediate fraction which is removed from the pressure column above the air feed.
  • the removal point can be, for example, at the intermediate point at which the oxygen-enriched fraction is removed, at the top of the pressure column, or at each point arranged between these two points.
  • the intermediate fraction is practically N 2 O-free and can therefore be fed to the low-pressure column after the work-relieving expansion
  • a portion of the compressed and pre-cleaned air can be branched off upstream of the pressure column and expanded to perform the work, but the relaxed air must then not be fed to the pressure column above the air supply or to a working section of the rectification system downstream of the pressure column, but is, for example, added to a residual stream and removed from the process
  • kite can be increased by increasing the pressure in the intermediate fraction.
  • the intermediate fraction can be removed from the pressure column in gaseous form, heated and compressed in the gaseous state before the work-related relaxation, for example. It is advantageous to use at least part of the mechanical energy for this compression of work-relieving relaxation is obtained.
  • the pressure after compression is, for example, 7 to 15 bar, preferably 8 to 12 bar. The amount of the pressure difference depends here, as in the following paragraph, on the cooling requirement of a specific system
  • the intermediate fraction upstream of the work-relieving expansion is drawn off in the liquid state from the pressure column, subjected to a pressure increase in the liquid state, evaporated and heated by indirect heat exchange.
  • the liquid pressure increase leads to a pressure of, for example, 7 to 15 bar, preferably 8 to 12 bar
  • the method according to the invention is operated in connection with an internal compression process in which a product stream is brought to pressure in a liquid state (for example 7 to 50 bar, preferably 9 up to 30 bar) and then evaporated against a heating fluid under high pressure (e.g. 7 to 50 bar, preferably 9 to 30 bar), it is advisable to deviate from the usual procedure (the pressures depend in individual cases on the required product pressure) instead of one
  • a heating fluid for example 7 to 50 bar, preferably 9 up to 30 bar
  • a heating fluid under high pressure e.g. 7 to 50 bar, preferably 9 to 30 bar
  • part of the bottom liquid of the pressure column can be evaporated and the gas formed in this way can be returned to the pressure column.
  • This optional bottom heating of the pressure column is preferably effected by a condenser-evaporator, which is acted on with a suitable process gas as heating medium Turnover increased in the section of the pressure column that is below the removal of the oxygen-enriched fraction.Therefore, further substances, in particular krypton and / or methane, are washed into the sump of the pressure column. This effect is further enhanced if the pressure column in this case has a further mass transfer section which is arranged below the point at which the compressed and pre-cleaned feed air is introduced into the pressure column and has the scope of some theoretical ground
  • the invention also relates to a device for the low-temperature decomposition of air according to claim 11 or 12
  • the pressure column in the sense of the invention is then formed by the combination of this guard column with a main column.
  • the feed air is led into the guard column.
  • the rinsing fraction is drawn off in liquid form from the sump of the guard column.
  • At the head of the guard column at least one theoretical or practical base above the air supply gas is drawn off and introduced into the lower area of the main column.
  • the oxygenated fraction is then withdrawn from the bottom of the main column.
  • the main column is part of the existing rectification system.
  • the top gas from the guard column is introduced into the main column via the previous feed air line, and the oxygen-enriched fraction can be drawn off via the existing bottom liquid line.
  • the retrofitting can therefore be accomplished by providing a guard column to retain contaminants such as N 2 O that are difficult to escape. This method can also be useful when building an air separation plant, for example if a particularly low construction height is desired.
  • Figure 2 shows an embodiment of the invention with the extraction of krypton and / or xenon
  • Figure 3 shows a variant with a different method for the extraction of
  • Process cold and Figure 4 shows a process with the extraction of pressurized oxygen by means of internal compression.
  • FIG. 1 shows a double column system for nitrogen-oxygen separation.
  • Compressed feed air 1 is fed to pre-cleaning 2 and is preferably subjected to adsorption there. Water vapor and CO 2 are practically completely removed from the compressed feed air. In contrast, about 20 to 50% of N 2 0 is let through by a conventional molecular sieve.
  • the pre-cleaned feed air 3 is in a main heat exchanger 4 in indirect heat exchange cooled against decomposition products and completely fed via line 5 to the pressure column 6 of the rectification system.
  • the rectification system for nitrogen-oxygen separation also has a low-pressure column 7, which via a condenser-evaporator is the main condenser 8, with the pressure column 6 in heat exchange relationship at the head of the pressure column 6, pressure nitrogen 9 is generated, which is partially or completely fed to the main condenser 8 and is condensed there at least partially, preferably completely or essentially completely.
  • a part 11 of the nitrogen 10 liquefied in the main condenser 8 is fed in as a return to the pressure column 6.
  • At least part 12 of the remaining condensate is led to the upper area of a low-pressure column 7.
  • Evaporating bottom liquid of the low-pressure column evaporates on the evaporation side of the main condenser 8.
  • the steam generated rises in the low-pressure column in counterflow to the return flow liquid (the main con de ⁇ sator 8 is in the exemplary embodiment of the drawing directly in the sump of the low pressure column, alternatively it can be arranged outside the double column)
  • An oxygen-enriched fraction 13 is taken in liquid form from the pressure column 6 and fed to the low-pressure column 7 at an intermediate point as a further use fraction (14)
  • the oxygen-enriched fraction 13 is not drawn from the bottom of the pressure column, but from an intermediate point above a mass transfer section 15 is arranged, which corresponds to three theoretical plates in the example. It is therefore free of more volatile impurities such as xenon, C 2 H 4 , N 2 0 and C 3 H 8. Thus, no N 2 0 can get into and into the low-pressure column 7
  • Malfunctions in the Hauptko ⁇ densator 8 lead
  • the less volatile constituents are drawn off from the sump of the pressure column 6 with a liquid winding fraction 16 and fed in the liquid state to a cleaning stage 17 in which N 2 0 is removed.
  • N 2 0 removal is effected by means of adsorption.
  • the cleaned liquid winding fraction 18 is Together with the oxygen-enriched fraction 13, the low-pressure column 7 is fed in as an alternative. A separate feed is also possible a few floors below.
  • the entire feed air is fed into the pressure column 6 via the line 5, in particular, no feed air enters the low-pressure column 7 without pre-disassembly (for example via a Turbine)
  • the mass transfer section 15 below the removal of the oxygen-enriched fraction 13 can be formed by any known mass transfer element, for example by packing or any type of mass transfer tray, preferably sieve tray or bell and / or chimney tray with a very small amount of coil fraction
  • the oxygen product is withdrawn in gaseous form from the low-pressure column 7 via line 21, warmed in the main heat exchanger 4 and discharged as a product via line 22.
  • the withdrawal is arranged some theoretical or practical bottom above the sump of the low-pressure column in order to avoid more volatile components such as krypton and / or To keep xenon away from the oxygen product These more volatile components are withdrawn from the bottom liquid of the low-pressure column using a liquid product or winding stream 24.
  • oxygen can be supplied as a krypton- and xenon-free liquid product via line 23 and / or as a gaseous product which still contains krypton and Xenon contains, can be removed via line 25 (the heating of the product to be drawn off via line 25 and the supercooling of the oxygen-enriched fraction 13 are not shown in the drawing)
  • a nitrogen-containing fraction 19 is drawn off as a gaseous nitrogen product or residual gas above the head of the low-pressure column 7 and heated in the main heat exchanger 4.
  • the heated nitrogen-containing fraction 20 can be used in part as a regeneration gas for the pre-cleaning 2
  • the cold process is obtained in the exemplary embodiment by means of work-relieving expansion of an intermediate fraction 30, which is withdrawn from the pressure column 6 in the amount of the deduction of the oxygen-enriched fraction 13 or higher in gaseous form Compressed 5 bar to 7 bar and fed to the main heat exchanger 4 after cooling 33 (line 34).
  • the compressed air is removed from the main heat exchanger at an intermediate temperature (line 35 and a relaxation machine 36 are fed in). Downstream of the work-relieving relaxation 36 to 1 2 bar it is via line 37 of the low pressure column 7 fed at an intermediate point.
  • both the removal from the pressure column 6 and the feed into the low-pressure column 7 are located at those intermediate points at which the oxygen-rich fraction 13, 14 is also drawn off or introduced.
  • At least a part of the energy required for the compression of the heated gas fraction 31 is formed by the mechanical energy generated during the relaxation 36;
  • the expansion machine 36 and the compressor 32 are preferably coupled mechanically.
  • the compression 32 can be omitted; then it is sufficient to warm the gas fraction 30 only up to a medium temperature and then to supply it directly via line 35 to the work relaxation 36.
  • FIG. 2 shows a variant of the method according to FIG. 1, in which krypton and xenon are obtained in addition to oxygen and nitrogen.
  • further process steps and devices for krypton / xenon extraction are provided, which are located outside the rectification system for nitrogen-oxygen separation.
  • Oxygen fraction 24 which is drawn off from the bottom of the low-pressure column, serves as a common use for system 202 for krypton / xenon extraction.
  • the cleaned rinsing fraction downstream of the cleaning stage 17 is partly or completely fed via line 201 to the system 202 for krypton / xenon extraction, preferably in the liquid state. It can in particular be fed at a suitable point into an exchange column which is used to produce a krypton- and xenone-containing but oxygen-free mixture, or into another column for the pre-enrichment of krypton and / or xenon. The feed point is below the head of the corresponding column.
  • an intermediate fraction 340 in the amount of the withdrawal of the oxygen-enriched fraction 13 or higher in liquid form is removed from the pressure column 6. It is brought to an increased pressure of, for example, 7 bar in liquid form by a pump 341 and then via line 342 to the Main heat exchanger 4 supplied. There it is evaporated under the increased pressure and warmed to an intermediate temperature.
  • the warmed intermediate fraction will Via line 335 fed to a relaxation machine 336 Downstream of the work-relieving relaxation 336, it is fed via line 337 to the low-pressure column 7 at an intermediate point or discharged as a product
  • Intermediate fraction 342 is a heating medium, which is taken out in gaseous form via line 330 from an intermediate point (alternatively from the head) of the pressure column 6 and heated in the main heat exchanger 4.
  • the heated heating medium 331 is compressed in a compressor 332, for example, to 8 bar and, after cooling 333, is returned to the main heat exchanger 4 fed (line 334) There it is cooled and finally at least partially condensed.
  • the condensed heating medium 343 is expanded back into the pressure column, preferably at the point of its removal via line 330 or somewhat higher
  • At least a part of the energy required for the compression of the heated heating means 331 is generated by the mechanical energy generated during the work-relieving expansion 336, preferably the expansion machine 336 and the compressor 332 are mechanically coupled for this purpose
  • the tapping points of the intermediate fraction to be relaxed for work and the heating medium are at the same level, namely at that of the deduction of the oxygen-enriched fraction 13. They could also be at different levels, for example it is possible for both to be at different points above the Removal of the oxygen-enriched fraction 13 to be arranged. This also shifts the feed point in the low-pressure column and the pressure column
  • the process shown schematically in FIG. 4 serves to obtain gaseous oxygen under increased pressure by internal compression.
  • liquid oxygen 423 from the low-pressure column 7 is brought to an increased pressure of, for example, 9 bar in a pump 452.
  • the liquid 453 is brought to the main heat exchanger under the high pressure 4 fed and evaporated and heated there via line 422, the gaseous printed product is withdrawn
  • An intermediate fraction serves as heating fluid for the evaporation of the liquid oxygen 453, which is taken out in gaseous form via line 430 from an intermediate point (alternatively from the head) of the pressure column 6 and is heated in the main heat exchanger 4 20 bar compressed and after
  • After-cooling 433 is again fed to the main heat exchanger 4 (line 454), where it is cooled and at least partially condensed.
  • the condensed heating fluid 455 is throttled back into the pressure column, preferably at the point of its removal via line 430 or somewhat higher part 434 of those compressed in the compressor 432 Intermediate fraction 430/431 from the pressure column can be used for the
  • Cold production can be used by removing it from the main heat exchanger at an intermediate temperature (line 35) and feeding it to a decompression machine 36.
  • the fraction that is relaxed for work is fed via line 37 downstream of the work-related expansion 36 to the low-pressure column 7 at an intermediate point.
  • it can be pricked Line 451 shown are returned to the pressure column 6
  • FIGS. 3 and 4 can be combined with the crypto / xenon extraction according to FIG. 2

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Abstract

Removal of nitrous oxides in an air separation plant involves treatment of liquid, from the high-pressure column, in which it is concentrated. It is important to remove nitrous oxide, which has a comparatively high melting point, from the circuit before solid particles block the heat exchangers. This is done by occasionally purging the sump of high pressure column (6) at (16) and passing the liquid, which will contain all of the nitrous oxide, into a cleaning vessel (17) in which the nitrous oxide is removed by physical adsorption. Alternatively the purge liquid is warmed in a heat exchanger to a point where the nitrous oxide can be separated as a solid or liquid fraction. A counterflow material exchange method could also be used. The cleaned fluid then rejoins the process via line (18). The main flow of the oxygen enriched portion is removed at (13), at least one theoretical, or practical, floor (material exchange section (15)) above the air inlet (5), to continue the process in a conventional manner in the low-pressure column (7). Krypton and Xenon, also present in the sump liquid, can be concentrated and separated from the nitrous-oxide-free liquid leaving vessel (17). Methods for recovering cooling energy, involving further compression and conventional expansion through a turbine, are described.

Description

Beschreibung description
Verfahren und Vorrichtung zur Tieftemperaturzerlequnq von LuftMethod and device for the low-temperature decomposition of air
Die Erfindung betrifft ein Verfahren zur Tieftemperaturzeiieguπg von Luft, bei dem verdichtete und vorgereinigte Einsatzluft in ein Rektifiziersystem zur Stickstoff- Sauerstoff-Trennung eingeleitet wird, das eine Drucksaule aufweist, wobei mindestens ein Teil der verdichteten und vorgereiπigten Einsatzluft der Drucksaule zugespeist wird und wobei eine sauerstoffangereicherte Fraktion der Drucksaule entnommen und einem weiteren Arbeitsschπtt innerhalb des Rektifiziersystems zugeleitet wirdThe invention relates to a method for low-temperature air, in which compressed and pre-cleaned feed air is introduced into a rectification system for nitrogen-oxygen separation, which has a pressure column, at least part of the compressed and pre-cleaned feed air being fed to the pressure column and an oxygen-enriched one Fraction of the pressure column is removed and fed to another Arbeitsschπtt within the rectification system
Derartige Prozesse sind zum Beispiel aus Hausen/Linde, Tieftemperaturtechnik, 2 Auflage 1985, Kapitel 4 (Seiten 281 bis 337) bekannt Bei dem Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung kann es sich um ein Einsaulensystem mit einer einzigen Säule, der Drucksauie im Sinne der Erfindung, um ein Zweisaulensystem mit einer Drucksaule und einer Niederdrucksaule oder um ein Mehrsaulensystem mit weiteren Trennsaulen zur Stickstoff-Sauerstoff-Trennung handeln In Hausen/Linde sind mehrere Beispiele für Einsaulensysteme gezeigt (Seite 282, Bild 4 1 und 4 2 , Seite 287, Bild 4 4, Seiten 329/330, Bild 4 30 , 4 31 und 4 32 ), die Erfindung ist insbesondere auf eine Einzelsaule mit Kopfkuhlung durch eine sauerstoffangereicherte Flüssigkeit aus der Drucksaule anwendbar (Hausen/Linde, Seite 330, Bild 4 31 ) Auch Beispiele für Zweisaulensysteme sind in Hausen/Linde zu finden (Seite 284, Bild 4 3 und verschiedene Beispiele in den Abschnitten 4 5 1 und 4 5 2) Zur Erzeugung von aufsteigendem Dampf für die Niederdrucksaule wird ein Teil der Sumpfflussigkeit in einem Kondensator-Verdampfer (meist als Hauptkondensator bezeichnet) verdampft, der beispielsweise mit einer Gasfraktion aus der Drucksaule oder mit Luft als Heizmittel betπeben wird Der Kondensator- Verdampfer kann durch einen oder mehrere Warmetauscherblocke realisiert werden die beispielsweise als Umlauf- und/oder Failfilmverdampfer betrieben werdenSuch processes are known, for example, from Hausen / Linde, Low Temperature Technology, 2 Edition 1985, Chapter 4 (pages 281 to 337). The rectification system for nitrogen-oxygen separation can be a single column system with a single column, the pressure suction in the sense of Invention to deal with a two-column system with a pressure column and a low-pressure column or a multi-column system with further separation columns for nitrogen-oxygen separation Several examples of single column systems are shown in Hausen / Linde (page 282, picture 4 1 and 4 2, page 287, picture 4 4, pages 329/330, picture 4 30, 4 31 and 4 32), the invention is particularly applicable to a single column with head cooling by means of an oxygen-enriched liquid from the pressure column (Hausen / Linde, page 330, picture 4 31) Also examples for two-column systems can be found in Hausen / Linde (page 284, picture 4 3 and various examples in sections 4 5 1 and 4 5 2) For the generation of ascending D Ampf for the low-pressure column, part of the bottom liquid is evaporated in a condenser-evaporator (usually referred to as the main condenser), which is used, for example, with a gas fraction from the pressure column or with air as a heating medium.The condenser-evaporator can be implemented by one or more heat exchanger blocks for example, operated as a circulation and / or fail film evaporator
Das Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung im Sinne der Erfindung umfaßt außerdem Wärmetauscher wie etwa Kondensator-Verdampfer die zum BetπβD der Trennsaule(n) zur Stickstoff-Sauerstoff-Trennung benotigt werden (insbesondere den Hauptkondensator einer Doppelsaule oder den Kopfkondensator einer Eiπzelsaule) Das er indungsgemaße Verfahren und die entsprechende Vorrichtung können bei Bedarf außerhalb des Rektifiziersystems zur Stickstoff- Sauerstoff-Trennung zusätzliche Trennsaulen zur Gewinnung von weiteren Luftbestandteilen aufweisen etwa von Edelgasen wie Argon Helium Neon Krypton oder Xenon (siehe Hausen/Linde, Kapitel 4 5 4)The rectification system for nitrogen-oxygen separation in the sense of the invention also comprises heat exchangers such as condenser evaporators which are required for the operation of the separation column (s) for nitrogen-oxygen separation (In particular the main capacitor of a double column or the top capacitor of a single column) The method and the corresponding device according to the invention can, if necessary, have additional separation columns for the extraction of further air components, for example noble gases such as argon helium neon krypton or xenon, outside the rectification system for nitrogen-oxygen separation (see Hausen / Linde, Chapter 4 5 4)
Üblicherweise wird die sauerstoffangereicherte Fraktion aus dem Sumpfbereich der Drucksaule entnommen, bevor sie einem weiteren Arbeitsschπtt innerhalb des Rektifiziersystems zugeleitet wird Dieser weitere Arbeitsschπtt kann beispielsweise durch die weitere Auftrennung in der Niederdrucksaule eines Doppelsaulensystems oder durch eine Verdampfung, beispielsweise im Kopfkondensator eines Einsaulensystems gebildet werden Damit werden sämtliche schwererfiuchtigeπ Verunreinigungen der Einsatzluft, die in der Vorreinigung stromaufwärts der Einleitung in das Rektifiziersystem nicht entfernt wurden, mit der sauerstoffangereicherten Fraktion in den nachfolgenden Arbeitsschπtt weitertransportiert (Unter "schwererfluchtigen Verunreinigungen" werden hier Komponenten der Einsatzluft verstanden, deren Siedepunkt hoher als derjenige von Sauerstoff ist )The oxygen-enriched fraction is usually removed from the sump area of the pressure column before it is fed to a further work step within the rectification system. This further work step can be formed, for example, by further separation in the low-pressure column of a double-column system or by evaporation, for example in the top condenser of a single-column system All heavier impurities in the feed air, which were not removed in the pre-cleaning upstream of the introduction into the rectification system, are further transported with the oxygen-enriched fraction in the subsequent work steps ("heavily contaminated contaminants" are components of the feed air whose boiling point is higher than that of oxygen )
Insbesondere bei nachfolgenden Verdampfungsprozesseπ können sich solche schwererfluchtigen Verunreinigungen weiter anreichern Manche dieser schwererfluchtigen Stoffe insbesondere N20, können als Feststoffe ausfallen und müssen von Zeit zu Zeit entfernt werden, damit eine Verstopfung von Warmetauscherpassageπ in den entsprechenden Verdampfern (beispielsweise im Hauptkondensator eines Doppelsaulensystems) vermieden wird Um die ausgeschiedenen Feststoffe zu beseitigen, muß die gesamte Anlage abgeschaltet werden Dies kann bei einer großen Luftzerlegungsanlage einen Betπebsstillstand von beispielsweise zwei bis fünf Tagen bedeuten Diese Problematik wird in Wenning, Lachgas in Luftzerlegungsanlagen, Lmde-Beπchte aus Technik und Wissenschaft 77/1998, 32-36 geschildert Hier und in US 5629208 wird als Losung vorgeschlagen N20 aus mit Hilfe einer stärkeren Spulung der im Hauptkondensator anstehenden Flüssigkeit auszuschleusen Es hat sich jedoch herausgestellt daß diese Maßnahme nicht in allen Fallen ausreicht um die betriebstechnisch höchst unerwünschte Abschaltung der Luftzerlegungsanlage zu vermeiden Als Losung für dieses Problem bieten sich verschiedene für den Fachmann verfugbare Methoden anParticularly in subsequent evaporation processes, such less volatile impurities can accumulate further. Some of these less volatile substances, in particular N 2 O, can precipitate out as solids and must be removed from time to time so that the heat exchanger passage in the corresponding evaporators (for example in the main condenser of a double column system) is not blocked To remove the separated solids, the entire plant must be switched off. In a large air separation plant, this can mean a shutdown of, for example, two to five days. This problem will be solved in Wenning, nitrous oxide in air separation plants, lmde reports from technology and science 77/1998, 32-36 described here and in US 5629208, the proposed solution is to discharge N 2 0 with the aid of stronger rinsing of the liquid present in the main condenser. However, it has been found that this measure not sufficient in all cases to avoid the highly undesirable shutdown of the air separation plant Various methods available to the person skilled in the art offer a solution to this problem
Zum einen konnte eine Reinigungseinrichtung eingesetzt werden, die die unerwünschten Stoffe aus der sauerstoffangereicherten Fraktion entfernt Dabei wird beispielsweise die gesamte sauerstoffangereicherte Fraktion (bei einer Doppelsaule die Sumpfflussigkeit der Drucksaule) in flussiger Form über einen Adsorber zur Entfernung von N20 gefuhrt (Flussigadsorber wurden früher an derselben Stelle zur Acetylenentfernung eingesetzt ) Dieses Vorgehen lost die betπebstechnischenOn the one hand, it was possible to use a cleaning device which removes the undesirable substances from the oxygen-enriched fraction.For example, the entire oxygen-enriched fraction (in the case of a double column, the bottom liquid of the pressure column) is passed in liquid form via an adsorber to remove N 2 0 (liquid adsorbers used to be used at the same point for acetylene removal) This procedure triggers the operational engineering
Probleme in dem Verdampfer bedeutet aber einen relativ hohen Investitionsaufwand Außerdem muß der Adsorber von Zeit zu Zeit regeneriert werden, was selbst bei einer umschaltbaren Einrichtung zu weiterem betπebstechnischen Aufwand fuhrtProblems in the evaporator, however, mean a relatively high investment outlay. In addition, the adsorber has to be regenerated from time to time, which leads to additional operational outlay even with a switchable device
Zum anderen ist aus US 5471842 bekannt, schwererfluchtige Komponenten bereits in der Drucksaule auszuschleusen, indem an deren Sumpf eine Spulfraktion flussig abgezogen und die in der Niederdrucksaule weiterzuverarbeitende sauerstoffangereicherte Fraktion oberhalb der Luftzuspeisung entnommen wird Die Spulfraktioπ wird dabei flussig auf sehr hohen Druck gebracht, im Hauptwarmetauscher gegen hochverdichtete Einsatzluft verdampft, stromaufwärts der Vorreinigung der Luft der Einsatzluft zugemischt und mit dieser in die Drucksaule zuruckgeleitet Diese Methode funktioniert zwar, wie in US 5471842 angegeben, für die Ausschleusung von C02, das im Molekularsieb der Vorreinigung wirkungsvoll zurückgehalten wird Die N20-Problematιk wird in US 5471842 jedoch nicht erwähnt Das dortige Verfahren ist zur sicheren Ausschleusung von N20 nicht geeignet (siehe Artikel von Wenning, Abschnitt 6), es kann unter Umstanden eine Verstopfung der Passagen des Hauptwarmetauschers durch ausfallendes N20 vorkommen was eine Aπwarmung dieses Apparats notwendig machteOn the other hand, it is known from US 5471842 to discharge volatile components already in the pressure column, in that a coil fraction is drawn off at the bottom of the column in liquid form and the oxygen-enriched fraction to be processed further in the low-pressure column is removed above the air supply upstream of the pre-cleaning the air of the feed air evaporates against highly compressed feed air, mixed and with this in the Drucksaule zuruckgeleitet this method works, although, as stated in US 5471842, for the discharge of C0 2, which is retained effectively in the molecular sieve pre-cleaning, the N 2 0 -Problematιk is not mentioned in US 5471842. The method there is not suitable for the safe removal of N 2 0 (see article by Wenning, section 6), it may be clogged the passages of the main heat exchanger due to the failure of N 2 0 occur which made it necessary to warm this apparatus
In Abänderung des in US 5471842 vorgeschlagenen Verfahrens zur C02- Ausschleusung wäre es möglich die im Sumpf der Drucksaule abgezogene Spulfraktion völlig aus dem Verfahren zu entfernen in dem man sie - gegebenenfalls nach Ruckgewinnung eines Teils ihrer Kalte - verwirft Die Spulfraκtιon kann beispielsweise in flussigem Zustanα unmittelbar verworfen werden indem sie nach dem Abfuhren aus der Drucksaule zum Beispiel über einen Ejektor in die Atmosphäre abgegeben wird Alternativ dazu kann sie durch indirekten Wärmeaustausch mit einem Heizmtttel verdampft und/oder angewärmt und anschließend in gasformigem Zustand verworfen werden Dadurch wird ein Teil der Energie zurückgewonnen, die in Form von Kalte in der Spulfraktion enthalten ist Die Verdampfung sollte bei so hoher Temperatur erfolgen, daß ein Ausfallen von schwererfluchtigenIn a modification of the method proposed in US 5471842 for the removal of CO 2 , it would be possible to completely remove the coil fraction drawn off in the bottom of the pressure column from the method in which it is discarded, possibly after recovery of part of its cold. The coil fraction can, for example, be in a liquid state can be discarded immediately after being discharged from the pressure column, for example into the atmosphere via an ejector Alternatively, it can be evaporated and / or warmed by indirect heat exchange with a heating medium and then discarded in the gaseous state.This recovers part of the energy contained in the coil fraction in the form of cold.The evaporation should take place at such a high temperature that a failure of more volatile
Verunreinigungen vermieden wird, beispielsweise durch Einleiten der flussigen Spulfraktion in eine Restgasfraktion bei mittlerer Temperatur Eine andere Möglichkeit ist die Rückgewinnung der Kalte in einem Wärmeaustauscher mit umschaltbaren Passagen (Revex) Alle diese Methoden können in bestimmten Anlagen sinnvoll sein, haben jedoch den Nachteil, daß die an der Spulfraktion verrichtete Trennarbeit verlorengeht und damit ein hoher betriebstechnischer Aufwand in Form von zusätzlichem Energiebedarf bestehtContamination is avoided, for example by introducing the liquid coil fraction into a residual gas fraction at medium temperature.Another possibility is to recover the cold in a heat exchanger with switchable passages (Revex) .All these methods can be useful in certain systems, but have the disadvantage that the Separation work performed on the winding fraction is lost and there is thus a high level of operational expenditure in the form of additional energy requirements
Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art und eine entsprechende Vorπchtung so auszugestalten, daß der betπebstechnische Aufwand im gesamten Prozeß besonders niedπg gehalten werden kannThe invention is therefore based on the object of designing a method of the type mentioned at the beginning and a corresponding device in such a way that the outlay in terms of operating technology can be kept particularly low in the entire process
Diese Aufgabe wird durch die Merkmale des Patentanspruchs 1 gelost Bei dem erfindungsgemaßen Prozeß wird die Spulfraktion, die durch mindestens einen Teil, vorzugsweise die Gesamtheit der Sumpfflussigkeit der Drucksaule gebildet wird, ohne vorherige Verdampfung einer Einrichtung zur Entfernung von N20 zugeführtThis object is achieved by the features of claim 1. In the process according to the invention, the winding fraction, which is formed by at least part, preferably all, of the bottom liquid of the pressure column, is fed to a device for removing N 2 O without prior evaporation
Dadurch kann die gereinigte Spulfraktion stromabwärts dieser Einπchtung weiteren Arbeitsschπtten innerhalb oder außerhalb des Rektifiziersystems zur Stickstoff- Sauerstoff-Trennung zugeführt werden, ohne daß im Rahmen dieser Arbeitsschπtte die Anreicherung von N20 droht Der weitere Arbeitsschπtt kann beispielsweise eine Säule zur Stickstoff-Sauerstoff-Trennung oder einen Kondensator-Verdampfer zur Erzeugung von Rucklauf für eine derartige Säule aufweisen, etwa die Niederdrucksaule eines Zweisaulensystems zur Stickstoff-Sauerstoff-Trennung oder den Kopfkondensator der DrucksauleAs a result, the purified coil fraction downstream of this device can be fed to further workstations inside or outside the rectification system for nitrogen-oxygen separation without there being any risk of N 2 0 accumulation in the course of this workstep. The further workstep can, for example, be a column for nitrogen-oxygen separation or have a condenser-evaporator for generating reflux for such a column, such as the low-pressure column of a two-column system for nitrogen-oxygen separation or the top condenser of the pressure column
Der Stoffaustauschabschnitt zwischen der Stelle der Einsatzluftzufuhr (in der Regel am Sumpf der Drucksaule) und αer Entnahme der sauerstoffangereicnerten Fraktion ermöglicht ein weitgehend vollständiges Auswaschen der schwererfluchtigen Verunreinigungen insbesondere von N20 aus der Einsatzluft in den Sumpf der Drucksaule Er wird entweder durch mindestens einen praktischen Boden oder durch einen Packungsabschnitt mit einer Trenπwirkung von mindestens einem theoretischen Boden gebildet Vorzugsweise befinden sich 1 bis 10, höchst vorzugsweise 3 bis 5 theoretische oder praktische Boden zwischen Luftzuspeisung beziehungsweise Drucksaulensumpf einerseits und Entnahmestelle der sauerstoffangereicherten Flüssigkeit andererseits (Für den Fall, daß in diesem Abschnitt ausschließlich praktische Boden als Stoffaustauschelemente verwendet werden, gelten die Angaben in praktischen Bodenzahlen, falls Packung, Fullkorper oder Kombinationen verschiedener Typen von Stoffaustauschelementen eingesetzt werden, sind die Angaben in theoretischen Bodenzahlen anzuwenden )The mass transfer section between the point at which the feed air is supplied (usually at the bottom of the pressure column) and the removal of the oxygen-enriched fraction enables a largely complete washing out of the less volatile Contamination, in particular of N 2 0, from the feed air into the sump of the pressure column. It is formed either by at least one practical base or by a packing section with a separation effect from at least one theoretical base. There are preferably 1 to 10, most preferably 3 to 5 theoretical or practical Soil between the air supply or pressure column sump on the one hand and the point of withdrawal of the oxygen-enriched liquid on the other hand (In the event that only practical soils are used as material exchange elements in this section, the information in practical plate numbers applies if packaging, full bodies or combinations of different types of material exchange elements are used) apply the information in theoretical soil numbers)
Im Rahmen des erfindungsgemaßen Verfahrens kann die Drucksaule als ein einziger Behalter realisiert sein Alternativ dazu können unterschiedliche Abschnitte durch getrennte Behalter umschlossen sein Beispielsweise kann derIn the context of the method according to the invention, the pressure column can be implemented as a single container. Alternatively, different sections can be enclosed by separate containers
Stoffaustauschabschnitt, der zum Auswaschen von N20 dient, separat vom Rest der Drucksaule aufgebaut sein (siehe Vorπchtung gemäß Patentanspruch 11)Mass transfer section, which serves to wash out N 2 0, be constructed separately from the rest of the pressure column (see device according to claim 11)
Mit einem derartigen Stoffaustauschabschnitt zwischen Luftzuspeisung und Entnahme der sauerstoffangereicherten Fraktion können die wichtigsten schwererfluchtigen Verunreinigungen praktisch vollständig aus nachfolgenden Arbeitsschπtten zurückgehalten werden Die sauerstoffangereicherte Fraktion enthalt beispielsweise weniger als 1 ppb N20 (molare Konzentration kleiner als 10"9), vorzugsweise liegt die molare N2O-Konzentratιon bei 10"12 oder darunterWith such a mass transfer section between the air supply and the removal of the oxygen-enriched fraction, the most important less volatile impurities can be retained practically completely from subsequent work steps. The oxygen-enriched fraction contains, for example, less than 1 ppb N 2 O (molar concentration less than 10 "9 ), preferably the molar N 2 O concentrate at 10 "12 or below
Die schwererfluchtigen Verunreinigungen wie N20 werden mit der flussigen Spulfraktion aus dem Sumpf der Drucksaule abgeführt Die Entnahme der Spulfraktion kann kontinuierlich oder diskontinuierlich erfolgen Die Menge an abgezogener Spulfraktion wird von der erwünschten beziehungsweise erlaubten Konzentration schwererfluchtiger Komponenten in der Spulfraktion bestimmt In der Regel wird sie so eingestellt, daß kein Feststoffausfall im Sumpf der Drucksaule auftritt unter Umstanden ist aber auch eine höhere Anreicherung mit Feststoffausfall möglich Die Spulfraktionsmenge betragt beispielsweise mindestens 0 1 mol% der in die Drucksaule eingespeisten Einsatzluftmenge vorzugsweise 0 15 mol% bis 10 mol% höchst vorzugsweise 0 3 mol% bis 5 mol% der Einsatzluftmenge (Die Angaben über die Spulfraktionsmenge sind - insbesondere bei diskontinuierlicher Entnahme - als zeitliches Mittel der Spulfraktionsmenge zu verstehen.)The less volatile impurities such as N 2 0 are removed with the liquid coil fraction from the bottom of the pressure column. The coil fraction can be removed continuously or discontinuously. The amount of coil fraction withdrawn is determined by the desired or permitted concentration of less volatile components in the coil fraction. As a rule, it is determined set so that no solids failure occurs in the sump of the pressure column, but under certain circumstances a higher enrichment with solids failure is also possible mol% to 5 mol% of the input air volume (the Information about the amount of reel fraction should be understood as a temporal average of the amount of reel fraction - especially in the case of discontinuous removal.)
Als Nebeneffekt der erfindungsgemäßen Maßnahmen stellt sich eine Verbesserung der Produktqualität des Sauerstoffprodukts ein, das gegebenenfalls aus der sauerstoffangereicherteπ Fraktion erzeugt wird.As a side effect of the measures according to the invention, there is an improvement in the product quality of the oxygen product, which is optionally produced from the oxygen-enriched fraction.
Vorzugsweise wird N20 in der Reinigungsstufe durch physikalische Adsorption aus der flüssigen Spülfraktion entfernt. Die Reinigungsstufe wird also durch einen Flüssigadsorber gebildet. Dieser Flüssigadsorber kann wesentlich kompakter ausgeführt werden als die früher zur Acetylenentfernung verwendeten Flüssigadsorber, über die die gesamte sauerstoffaπgereicherte Fraktion geleitet wurde.Preferably, N 2 0 is removed from the liquid rinsing fraction in the cleaning stage by physical adsorption. The cleaning stage is therefore formed by a liquid adsorber. This liquid adsorber can be made much more compact than the liquid adsorber previously used for acetylene removal, through which the entire oxygen-enriched fraction was passed.
Alternativ dazu kann das N20 in einem eigens dafür vorgesehenen Wärmetauscher niedergeschlagen werden, indem die flüssige Spülfraktion in der Reinigungsstufe durch indirekten Wärmeaustausch verdampft wird, wobei bei der Verdampfung N2O als Feststoff und/oder Flüssigkeit ausfällt. Sie können sich in dem Wärmeaustauscher ablagern, in dem die Verdampfung durchgeführt wird. Die Verdampfung muß in diesem Fall diskontinuierlich beziehungsweise in einem umschaltbaren Paar von rekuperativen oder regenerativen Wärmeaustauschern durchgeführt werden, so daß die abgelagerten Feststoffe in gewissen Zeitabständen entfernt werden. Es ist aber auch möglich, anfallende Flüssigkeit oder Feststoffe und die gereinigte Spülfraktion kontinuierlich abzuziehen.Alternatively, the N 2 0 can be precipitated in a specially provided heat exchanger by evaporating the liquid rinsing fraction in the cleaning stage by indirect heat exchange, with N 2 O being precipitated as a solid and / or liquid during evaporation. They can be deposited in the heat exchanger in which the evaporation is carried out. In this case, the evaporation must be carried out discontinuously or in a switchable pair of recuperative or regenerative heat exchangers, so that the deposited solids are removed at certain time intervals. However, it is also possible to continuously withdraw any liquid or solids and the cleaned rinsing fraction.
Eine weitere Möglichkeit besteht darin, N20 in der Reinigungsstufe durch Gegenstrom-Stoffaustausch aus der Spülfraktion zu entfernen. Dabei wird die Spülfraktion in flüssigem Zustand in eine zusätzliche Trennsäule eingeleitet, beispielsweise an einer Zwischenstelle oder am Kopf. Die Sumpffraktion der Trennsäule wird beispielsweise verworfen, während die Kopffraktion weiterverarbeitet wird, beispielsweise in der Drucksäule. Dem Sumpf der Trennsäule muß Wärme zugeführt werden, beispielsweise durch indirekten Wärmeaustausch mit einem Warmstrom (Übertragung fühlbarer Wärme) oder mit einem kondensierenden Gasstrom geeigneter Zusammensetzung mittels einer elektrisch betriebenen Heizung. Für den Fall, daß die Spülfraktion nicht unmittelbar am Kopf aufgegeben wird, ist außerdem eine Kopfkuhlung notwendig, beispielsweise durch indirekten Wärmeaustausch mit einem verdampfenden Prozeßstrom geeigneter Zusammensetzung und geeigneten DrucksAnother possibility is to remove N 2 0 in the purification stage by countercurrent mass transfer from the rinsing fraction. The rinsing fraction in the liquid state is introduced into an additional separation column, for example at an intermediate point or on the head. The bottom fraction of the separation column is discarded, for example, while the top fraction is processed further, for example in the pressure column. Heat must be supplied to the bottom of the separation column, for example by indirect heat exchange with a hot current (transfer of sensible heat) or with a condensing gas stream of suitable composition by means of an electrically operated heater. In the event that the rinsing fraction is not applied directly to the head in addition, head cooling is necessary, for example by indirect heat exchange with an evaporating process stream of suitable composition and suitable pressure
In der Regel wird eine der drei Methoden zur N20-Entfemung angewandtUsually one of the three methods for N 2 0 removal is used
Grundsätzlich ist auch eine Kombination zweier oder dreier Vaπanten möglich, in einem Beispieifall weist die Reinigungsstufe sowohl mindestens ein Adsorptioπsbett als auch mindestens ein umschaltbares Paar von Wärmetauschern aufIn principle, a combination of two or three variants is also possible; in one example, the cleaning stage has both at least one adsorption bed and at least one switchable pair of heat exchangers
Alternativ oder ergänzend zu der oben erwähnten Einleitung in das Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung kann die gereinigte Spulfraktion mindestens teilweise einem Arbeitsschritt außerhalb dieses Rektifiziersystems zugeführt werden Bevorzugt wird hierbei die Einspeisung in ein System zur rektifikatoπschen Gewinnung eines Edelgases, beispielsweise von Krypton und/oder Xenon Beispiele für derartige Systeme finden sich in der alteren deutschen Patentanmeldung 19823526 7 und in den hierzu korrespondierenden Anmeldungen desselben Anmelders, sowie in EP 96610 A, EP 222026 A, DE 1667639 A, DE 1122088 B oder in Streich et al , Gewinnung von Edelgasen in Luft- und Ammoniakanlagen, Linde- Beπchte aus Technik und Wissenschaft, 37/1975, 10-14 Die gereinigte Spulfraktion wird dabei vorzugsweise in flussigem Zustand mindestens teilweise in eine Austauschsaule eingeleitet, die dazu dient, Krypton und Xenon in ein Inertgas (Stickstoff oder Argon) einzubetten Diese Austauschsaule kann zusätzlich mit dem üblichen kryptoπ- und xenonhaltigen Einsatz beaufschlagt werden, nämlich der flussigen Sumpffraktion aus der Niederdrucksaule eines ZweisaulensystemsAs an alternative or in addition to the introduction into the rectification system for nitrogen-oxygen separation mentioned above, the purified winding fraction can at least partially be fed to a working step outside of this rectification system. In this case, feeding into a system for the rectification of a noble gas, for example krypton and / or Xenon Examples of such systems can be found in the older German patent application 19823526 7 and in the corresponding applications by the same applicant, as well as in EP 96610 A, EP 222026 A, DE 1667639 A, DE 1122088 B or in Streich et al, extraction of noble gases in Air and ammonia systems, Linde reports from technology and science, 37/1975, 10-14 The cleaned coil fraction is preferably at least partially introduced in a liquid state into an exchange column which is used to convert krypton and xenon into an inert gas (nitrogen or argon ) to embed this exchange pillar can also be used with the usual kryptoπ- and xenon-containing use, namely the liquid bottom fraction from the low pressure column of a two-column system
Vorzugsweise wird bei dem erfindungsgemaßen Verfahren die Gesamtluft, das heißt die gesamte Einsatzluft, die in dem Rektifiziersystem zerlegt wird, in die Drucksaule eingeleitet Die gesamte Einsatzluft wird vorzugsweise mindestens einen theoretischen oder praktischen Boden unterhalb der Stelle in die Drucksaule eingespeist an der die sauerstoffangereicherte Fraktion abgezogen wird Damit wird vermieden daß über eine Direkteinspeisung von Luft in weitere Arbeitsschπtte innerhalb des Rektifiziersystems (zum Beispiel über eine Luftturbine die in die Niederdrucksaule eines Zweisaulensystems fuhrt) unerwünschte schwererfluchtige Verunreinigungen in einen Aroeitsscnπtt stromabwärts der Drucksaule gelangen Im Rahmen der Erfindung ist es gunstig, wenn Verfahrenskalte durch arbeitsleistende Entspannung einer Zwischeπfraktion erzeugt wird, die der Drucksaule oberhalb der Luftzuspeisung entnommen wird Die Entnahmestelle kann beispielsweise an der Zwischenstelle liegen, an der die sauerstoffangereicherte Fraktion entnommen wird, am Kopf der Drucksaule, oder an jeder zwischen diesen beiden Punkten angeordneten Stelle Die Zwischenfraktion ist praktisch N20-freι und kann daher nach der arbeitsleistenden Entspannung der Niederdrucksaule zugeführt werdenIn the process according to the invention, the total air, that is to say the entire feed air which is broken down in the rectification system, is preferably introduced into the pressure column. The entire feed air is preferably fed into the pressure column at least one theoretical or practical base below the point at which the oxygen-enriched fraction is drawn off It is thus avoided that a direct feed of air into further working sections within the rectification system (for example via an air turbine which leads into the low pressure column of a two column system) undesirable less volatile impurities get into an aerodynamic downstream of the pressure column In the context of the invention, it is expedient if process cold is generated by work-relieving relaxation of an intermediate fraction which is removed from the pressure column above the air feed. The removal point can be, for example, at the intermediate point at which the oxygen-enriched fraction is removed, at the top of the pressure column, or at each point arranged between these two points. The intermediate fraction is practically N 2 O-free and can therefore be fed to the low-pressure column after the work-relieving expansion
Alternativ oder zusätzlich kann ein Teil der verdichteten und vorgereinigten Luft stromaufwärts der Drucksaule abgezweigt und arbeitsleistend entspannt werden, die entspannte Luft darf dann aber nicht der Drucksaule oberhalb der Luftzuspeisung oder einem Arbeitsschπtt des Rektifiziersystems stromabwärts der Drucksaule zugeführt werden, sondern wird beispielsweise einem Reststrom zugemischt und aus dem Verfahren entferntAlternatively or additionally, a portion of the compressed and pre-cleaned air can be branched off upstream of the pressure column and expanded to perform the work, but the relaxed air must then not be fed to the pressure column above the air supply or to a working section of the rectification system downstream of the pressure column, but is, for example, added to a residual stream and removed from the process
Die Kaiteerzeugung kann durch eine Druckerhohung in der Zwischenfraktion vergrößert werden Dazu kann die Zwischenfraktion vor der arbeitsleistenden Entspannung beispielsweise gasformig aus der Drucksaule entnommen, angewärmt und in gasformigem Zustand verdichtet werden Es ist gunstig, zu dieser Verdichtung mindestens einen Teil der mechanischen Energie einzusetzen, die bei der arbeitsleistenden Entspannung gewonnen wird Der Druck nach dem Verdichten betragt beispielsweise 7 bis 15 bar, vorzugsweise 8 bis 12 bar Die Hohe der Druckdifferenz hangt hier wie im folgenden Absatz vom Kältebedarf einer spezifischen Anlage abThe generation of kite can be increased by increasing the pressure in the intermediate fraction. For this purpose, the intermediate fraction can be removed from the pressure column in gaseous form, heated and compressed in the gaseous state before the work-related relaxation, for example. It is advantageous to use at least part of the mechanical energy for this compression of work-relieving relaxation is obtained. The pressure after compression is, for example, 7 to 15 bar, preferably 8 to 12 bar. The amount of the pressure difference depends here, as in the following paragraph, on the cooling requirement of a specific system
Alternativ dazu wird die Zwischeπfraktion stromaufwärts der arbeitsleistenden Entspannung in flüssigem Zustand aus der Drucksaule abgezogen, im flussigen Zustand einer Druckerhohung unterworfen, durch indirekten Wärmeaustausch verdampft und angewärmt Die flussige Druckerhohung fuhrt auf einen Druck von beispielsweise 7 bis 15 bar vorzugsweise 8 bis 12 barAlternatively, the intermediate fraction upstream of the work-relieving expansion is drawn off in the liquid state from the pressure column, subjected to a pressure increase in the liquid state, evaporated and heated by indirect heat exchange. The liquid pressure increase leads to a pressure of, for example, 7 to 15 bar, preferably 8 to 12 bar
Auch für den Fall daß das erfindungsgemaße Verfahren im Zusammenhang mit einem Innenverdichtungsprozeß betrieben wird bei dem ein Produktstrom in flussigem Zustand auf Druck gebracht (beispielsweise 7 bis 50 bar vorzugsweise 9 bis 30 bar) und anschließend gegen ein unter hohem Druck (beispielsweise 7 bis 50 bar, vorzugsweise 9 bis 30 bar) stehendes Heizfluid verdampft wird ist eine Abweichung von der üblichen Vorgehensweise sinnvoll (Die Drucke richten sich im Einzelfall nach dem geforderten Produktdruck ) Anstelle eines Teils der verdichteten und vorgereinigten Einsatzluft wird gemäß einer weiteren Vaπante der Erfindung eine praktisch N20-freιe Gasfraktion aus der Drucksaule als Heizfluid verwendet Diese wird mindestens einen theoretischen oder praktischen Boden oberhalb der Stelle entnommen, an der verdichtete und vorgereinigte Einsatzluft zugespeist wird, vorzugsweise an der Zwischenstelle, an der die sauerstoffangereicherte Fraktion entnommen wird, am Kopf der Drucksaule, oder an einer zwischen diesen beiden Punkten angeordneten Stelle Das Heizfluid wird angewärmt, verdichtet und schließlich gegen den flussig auf Druck gebrachten Produktstrom kondensiert Das Kondensat wird an geeigneter Stelle weiterverarbeitet, beispielsweise in der DrucksauleAlso in the event that the method according to the invention is operated in connection with an internal compression process in which a product stream is brought to pressure in a liquid state (for example 7 to 50 bar, preferably 9 up to 30 bar) and then evaporated against a heating fluid under high pressure (e.g. 7 to 50 bar, preferably 9 to 30 bar), it is advisable to deviate from the usual procedure (the pressures depend in individual cases on the required product pressure) instead of one According to a further variant of the invention, part of the compressed and pre-cleaned feed air is used as a heating fluid, a practically N 2 O-free gas fraction from the pressure column. This is taken from at least one theoretical or practical base above the point at which compressed and pre-cleaned feed air is fed in, preferably At the intermediate point at which the oxygen-enriched fraction is removed, at the top of the pressure column, or at a point located between these two points. The heating fluid is warmed up, compressed and finally condensed against the product stream, which is pressurized liquid. The condensate is at a suitable point processed, for example in the printing column
Bei dem erfindungsgemaßen Verfahren kann ein Teil der Sumpfflussigkeit der Drucksaule verdampft und das dabei entstandene Gas in die Drucksaule zuruckgeleitet werden Diese fakultative Sumpfheizung der Drucksaule wird vorzugsweise durch einen Kondensator-Verdampfer bewirkt, der mit einem geeigneten Prozeßgas als Heizmittel beaufschlagt wird Auf diese Weise wird der Umsatz in dem Abschnitt der Drucksaule erhöht, der unterhalb der Entnahme der sauerstoffangereicherten Fraktion liegt Damit werden weitere Stoffe insbesondere Krypton und/oder Methan in den Sumpf der Drucksaule gewaschen Dieser Effekt wird weiter verstärkt, wenn die Drucksauie in diesem Fall einen weiteren Stoffaustauschabschnitt aufweist, der unterhalb der Stelle angeordnet ist, an der die verdichtete und vorgereiπigte Einsatzluft in die Drucksaule eingeleitet wird und den Umfang einiger theoretischer Boden aufweistIn the method according to the invention, part of the bottom liquid of the pressure column can be evaporated and the gas formed in this way can be returned to the pressure column. This optional bottom heating of the pressure column is preferably effected by a condenser-evaporator, which is acted on with a suitable process gas as heating medium Turnover increased in the section of the pressure column that is below the removal of the oxygen-enriched fraction.Therefore, further substances, in particular krypton and / or methane, are washed into the sump of the pressure column.This effect is further enhanced if the pressure column in this case has a further mass transfer section which is arranged below the point at which the compressed and pre-cleaned feed air is introduced into the pressure column and has the scope of some theoretical ground
Die Erfindung betrifft außerdem eine Vorπchtung zur Tieftemperaturzerlegung von Luft gemäß Patentanspruch 11 oder 12The invention also relates to a device for the low-temperature decomposition of air according to claim 11 or 12
Insbesondere bei der Nachrüstung von bestehenden Anlagen mit dem erfindungsgemaßen Verfahren kann es gunstig sein die Saule(n) eines bestehenden Rektifiziersystems nicht umzubauen sondern eine zusätzliche Vorsaule zu verwenden die den Stoffaustauschabschnitt zwischen Luftzuspeisung und Entnahme der sauerstoffangereicherten Fraktion enthalt. Die Drucksaule im Sinne der Erfindung wird dann durch die Kombination dieser Vorsaule mit einer Hauptsaule gebildet. Die Einsatzluft wird in diesem Fall in die Vorsaule geleitet. Vom Sumpf der Vorsaule wird die Spülfraktion flüssig abgezogen. Am Kopf der Vorsaule wird mindestens einen theoretischen oder praktischen Boden oberhalb der Luftzuspeisung Gas abgezogen und in den unteren Bereich der Hauptsäule eingeleitet. Die sauerstoffangereicherte Fraktion wird dann vom Sumpf der Hauptsaule abgezogen. Im Falle des Umbaus einer konventionellen Anlage ist die Hauptsäuie Teil des bestehenden Rektifiziersystems. Über die frühere Einsatzluftleitung wird das Kopfgas der Vorsaule in die Hauptsäule eingeleitet und die sauerstoffangereicherte Fraktion kann über die bereits vorhandene frühere Sumpfflüssigkeitsleitung abgezogen werden. Das Nachrüsten kann also durch Beistellen einer Vorsäule zum Zurückhalten schwererfluchtiger Verunreinigungen wie N20 bewerkstelligt werden. Diese Methode kann auch beim Neubau einer Luftzerleguπgsanlage sinnvoll sein, beispielsweise wenn eine besonders niedπge Bauhöhe gewünscht ist.In particular when retrofitting existing systems with the method according to the invention, it can be advantageous not to convert the column (s) of an existing rectification system but to use an additional pre-column which separates the mass transfer section between air supply and extraction the oxygenated fraction. The pressure column in the sense of the invention is then formed by the combination of this guard column with a main column. In this case, the feed air is led into the guard column. The rinsing fraction is drawn off in liquid form from the sump of the guard column. At the head of the guard column, at least one theoretical or practical base above the air supply gas is drawn off and introduced into the lower area of the main column. The oxygenated fraction is then withdrawn from the bottom of the main column. If a conventional system is converted, the main column is part of the existing rectification system. The top gas from the guard column is introduced into the main column via the previous feed air line, and the oxygen-enriched fraction can be drawn off via the existing bottom liquid line. The retrofitting can therefore be accomplished by providing a guard column to retain contaminants such as N 2 O that are difficult to escape. This method can also be useful when building an air separation plant, for example if a particularly low construction height is desired.
Die Erfindung sowie weitere Einzelheiten der Erfindung werden im folgenden anhand von in den Zeichnungen schematisch dargestellten Ausführungsbeispielen näher erläutert. Hierbei zeigenThe invention and further details of the invention are explained in more detail below with reference to exemplary embodiments schematically illustrated in the drawings. Show here
Figur 1 eine Ausführuπgsfoπm mit einer Realisierung der Erfindung bei einem1 shows an embodiment with an implementation of the invention in a
Zweisauleπapparat, Figur 2 eine Ausführungsform der Erfindung mit der Gewinnung von Krypton und/oder Xenon, Figur 3 eine Variante mit abweichender Methode zur Gewinnung vonTwo-column apparatus, Figure 2 shows an embodiment of the invention with the extraction of krypton and / or xenon, Figure 3 shows a variant with a different method for the extraction of
Verfahrenskälte und Figur 4 ein Verfahren mit Gewinnung von Drucksauerstoff mittels Innenverdichtung.Process cold and Figure 4 shows a process with the extraction of pressurized oxygen by means of internal compression.
Die Zeichnung von Figur 1 zeigt ein Doppelsaulensystem zur Stickstoff-Sauerstoff- Trennung Verdichtete Einsatzluft 1 wird einer Vorreinigung 2 zugeleitet und dort vorzugsweise einer Adsorption unterworfen Dabei werden Wasserdampf und C02 praktisch vollständig aus der verdichteten Einsatzluft entfernt. N20 wird dagegen von einem üblichen Molekularsieb zu etwa 20 bis 50 % durchgelassen Die vorgereinigte Einsatzluft 3 wird in einem Hauptwarmetauscher 4 in indirektem Wärmeaustausch gegen Zerlegungsprodukte abgekühlt und über Leitung 5 vollständig der Drucksaule 6 des Rektifiziersystems zugeführt Das Rektifiziersystem zur Stickstoff-Sauerstoff- Trenπung weist außerdem eine Niederdrucksaule 7 auf, die über einen Kondensator- Verdampfer den Hauptkondensator 8, mit der Drucksaule 6 in Warmeaustauschbeziehung steht Am Kopf der Drucksaule 6 wird Druckstickstoff 9 erzeugt, der teilweise oder vollständig dem Hauptkondensator 8 zugeführt und dort mindestens teilweise, vorzugsweise vollständig oder im wesentlichen vollständig kondensiert wird Ein Teil 11 des im Hauptkondensator 8 verflüssigten Stickstoffs 10 wird als Rucklauf auf die Drucksaule 6 aufgegeben Mindestens ein Teil 12 des restlichen Kondensats wird zum oberen Bereich einer Niederdrucksaule 7 gefuhrt Auf der Verdampfungsseite des Hauptkondensators 8 verdampft Sumpfflussigkeit der Niederdrucksaule Der erzeugte Dampf steigt in der Niederdrucksaule im Gegenstrom zur Rucklaufflussigkeit auf (Der Hauptkondeπsator 8 befindet sich bei dem Ausfuhrungsbeispiel der Zeichnung unmittelbar im Sumpf der Niederdrucksaule, alternativ dazu kann er außerhalb der Doppelsaule angeordnet sein )The drawing in FIG. 1 shows a double column system for nitrogen-oxygen separation. Compressed feed air 1 is fed to pre-cleaning 2 and is preferably subjected to adsorption there. Water vapor and CO 2 are practically completely removed from the compressed feed air. In contrast, about 20 to 50% of N 2 0 is let through by a conventional molecular sieve. The pre-cleaned feed air 3 is in a main heat exchanger 4 in indirect heat exchange cooled against decomposition products and completely fed via line 5 to the pressure column 6 of the rectification system. The rectification system for nitrogen-oxygen separation also has a low-pressure column 7, which via a condenser-evaporator is the main condenser 8, with the pressure column 6 in heat exchange relationship at the head of the pressure column 6, pressure nitrogen 9 is generated, which is partially or completely fed to the main condenser 8 and is condensed there at least partially, preferably completely or essentially completely. A part 11 of the nitrogen 10 liquefied in the main condenser 8 is fed in as a return to the pressure column 6. At least part 12 of the remaining condensate is led to the upper area of a low-pressure column 7. Evaporating bottom liquid of the low-pressure column evaporates on the evaporation side of the main condenser 8. The steam generated rises in the low-pressure column in counterflow to the return flow liquid (the main con deπsator 8 is in the exemplary embodiment of the drawing directly in the sump of the low pressure column, alternatively it can be arranged outside the double column)
Der Drucksaule 6 wird eine sauerstoffangereicherte Fraktion 13 in flussiger Form entnommen und als weitere Einsatzfraktion der Niederdrucksaule 7 an einer Zwischenstelle zugeführt (14) Die sauerstoffangereicherte Fraktion 13 wird im Gegensatz zum Stand der Technik nicht vom Sumpf der Drucksaule abgezogen, sondern von einer Zwischenstelle die oberhalb eines Stoffaustauschabschπitts 15 angeordnet ist, der in dem Beispiel drei theoretischen Boden entspπcht Sie ist dadurch frei von schwererfluchtigen Verunreinigungen wie Xenon, C2H4, N20 und C3H8 Damit kann kein N20 in die Niederdrucksaule 7 gelangen und zu Betriebsstörungen im Hauptkoπdensator 8 fuhrenAn oxygen-enriched fraction 13 is taken in liquid form from the pressure column 6 and fed to the low-pressure column 7 at an intermediate point as a further use fraction (14) In contrast to the prior art, the oxygen-enriched fraction 13 is not drawn from the bottom of the pressure column, but from an intermediate point above a mass transfer section 15 is arranged, which corresponds to three theoretical plates in the example. It is therefore free of more volatile impurities such as xenon, C 2 H 4 , N 2 0 and C 3 H 8. Thus, no N 2 0 can get into and into the low-pressure column 7 Malfunctions in the Hauptkoπdensator 8 lead
Die schwererfluchtigen Bestandteile werden mit einer flüssigen Spulfraktion 16 vom Sumpf der Drucksaule 6 abgezogen und in flussigem Zustand einer Reinigungsstufe 17 zugeführt, in der N20 entfernt wird Die N20-Entfernung wird in dem Ausfuhrungsbeispiel mittels Adsorption bewirkt Die gereinigte flussige Spulfraktion 18 wird gemeinsam mit der sauerstoffangereicherten Fraktion 13 der Niederdrucksaule 7 zugespeist Alternativ ist auch eine getrennte Einspeisung einige Boden tiefer möglich Bei dem Ausfuhrungsbeispiel wird die gesamte Einsatzluft über die Leitung 5 in die Drucksaule 6 eingespeist insbesondere gelangt keine Einsatzluft ohne Vorzerlegung in die Niederorucksaule 7 (beispielsweise über eine Turbine) Der Stoffaustauschabschπitt 15 unterhalb der Entnahme der sauerstoffangereicherten Fraktion 13 kann durch jedes bekannte Stoffaustauschelement gebildet werden, beispielsweise durch Packung oder jede Art von Stoffaustauschboden vorzugsweise werden Siebboden oder bei einer sehr kleinen Menge an Spulfraktion Glocken- und/oder Kaminboden eingesetztThe less volatile constituents are drawn off from the sump of the pressure column 6 with a liquid winding fraction 16 and fed in the liquid state to a cleaning stage 17 in which N 2 0 is removed. In the exemplary embodiment, N 2 0 removal is effected by means of adsorption. The cleaned liquid winding fraction 18 is Together with the oxygen-enriched fraction 13, the low-pressure column 7 is fed in as an alternative. A separate feed is also possible a few floors below. In the exemplary embodiment, the entire feed air is fed into the pressure column 6 via the line 5, in particular, no feed air enters the low-pressure column 7 without pre-disassembly (for example via a Turbine) The mass transfer section 15 below the removal of the oxygen-enriched fraction 13 can be formed by any known mass transfer element, for example by packing or any type of mass transfer tray, preferably sieve tray or bell and / or chimney tray with a very small amount of coil fraction
In dem Beispiel wird das Sauerstoffprodukt über Leitung 21 gasformig aus der Niederdrucksaule 7 abgezogen, im Hauptwarmetauscher 4 angewärmt und über Leitung 22 als Produkt abgeführt Der Abzug ist einige theoretische beziehungsweise praktische Boden oberhalb des Sumpfs der Niederdrucksaule angeordnet, um schwererfluchtige Komponenten wie Krypton und/oder Xenon aus dem Sauerstoffprodukt fernzuhalten Diese schwererfluchtigen Komponenten werden mit einem Flussigprodukt- oder Spulstrom 24 aus der Sumpfflussigkeit der Niederdrucksaule abgezogen Alternativ oder zusätzlich zu dieser Methode kann Sauerstoff als krypton- und xenonfreies Flussigprodukt über Leitung 23 und/oder als gasformiges Produkt, das noch Krypton und Xenon enthalt, über Leitung 25 entnommen werden (Die Anwarmung des über Leitung 25 abzuziehenden Produkts und die Unterkühlung der sauerstoffangereicherten Fraktion 13 sind in der Zeichnung nicht dargestellt )In the example, the oxygen product is withdrawn in gaseous form from the low-pressure column 7 via line 21, warmed in the main heat exchanger 4 and discharged as a product via line 22. The withdrawal is arranged some theoretical or practical bottom above the sump of the low-pressure column in order to avoid more volatile components such as krypton and / or To keep xenon away from the oxygen product These more volatile components are withdrawn from the bottom liquid of the low-pressure column using a liquid product or winding stream 24. Alternatively or in addition to this method, oxygen can be supplied as a krypton- and xenon-free liquid product via line 23 and / or as a gaseous product which still contains krypton and Xenon contains, can be removed via line 25 (the heating of the product to be drawn off via line 25 and the supercooling of the oxygen-enriched fraction 13 are not shown in the drawing)
Über dem Kopf der Niederdrucksaule 7 wird eine stickstoffhaltige Fraktion 19 als gasformiges Stickstoffprodukt oder Restgas abgezogen und im Hauptwarmetauscher 4 angewärmt Die angewärmte stickstoffhaltige Fraktion 20 kann zum Teil als Regeneriergas für die Vorreinigung 2 genutzt werdenA nitrogen-containing fraction 19 is drawn off as a gaseous nitrogen product or residual gas above the head of the low-pressure column 7 and heated in the main heat exchanger 4. The heated nitrogen-containing fraction 20 can be used in part as a regeneration gas for the pre-cleaning 2
Verfahrens kalte wird in dem Ausfuhrungsbeispiel mittels arbeitsleistender Entspannung einer Zwischenfraktion 30 gewonnen, die in Hohe des Abzugs der sauerstoffaπgereicherten Fraktion 13 oder hoher in Gasform aus der Drucksaule 6 entnommen wird Sie wird im Gegenstrom zu Einsatzluft 3 im Hauptwarmetauscher 4 angewärmt in einem Verdichter 32 beispielsweise von 5 bar auf 7 bar komprimiert und nach Nachκuhlung 33 wieder dem Hauptwarmetauscher 4 zugeführt (Leitung 34) Die verdichtete Luft wird bei einer Zwischentemperatur dem Hauptwarmetauscher entnommen (Leitung 35 und einer Entspaπnungsmaschine 36 zugeleitet Stromabwarts der arbeitsleistenden Entspannung 36 auf 1 2 bar wird sie über Leitung 37 der Niederdrucksaule 7 an einer Zwischenstelle zugeführt. In dem konkreten Beispiel liegen sowohl die Entnahme aus der Drucksaule 6 als auch die Einspeisung in die Niederdrucksaule 7 an denjenigen Zwischenstelleπ, an denen auch die sauerstoffreiche Fraktion 13, 14 abgezogen beziehungsweise eingeleitet wird. Mindestens ein Teil der für die Verdichtung der angewärmten Gasfraktion 31 benötigten Energie wird durch die bei der arbeitsleistenden Entspannung 36 erzeugte mechanische Energie gebildet; vorzugsweise werden dazu die Entspannungsmaschine 36 und der Verdichter 32 mechanisch gekoppelt. In bestimmten Fällen kann die Verdichtung 32 entfallen; dann reicht es aus, die Gasfraktioπ 30 nur bis auf eine mittlere Temperatur anzuwärmen und dann direkt über Leitung 35 der arbeitsleistenden Entspannung 36 zuzuführen.The cold process is obtained in the exemplary embodiment by means of work-relieving expansion of an intermediate fraction 30, which is withdrawn from the pressure column 6 in the amount of the deduction of the oxygen-enriched fraction 13 or higher in gaseous form Compressed 5 bar to 7 bar and fed to the main heat exchanger 4 after cooling 33 (line 34). The compressed air is removed from the main heat exchanger at an intermediate temperature (line 35 and a relaxation machine 36 are fed in). Downstream of the work-relieving relaxation 36 to 1 2 bar it is via line 37 of the low pressure column 7 fed at an intermediate point. In the specific example, both the removal from the pressure column 6 and the feed into the low-pressure column 7 are located at those intermediate points at which the oxygen-rich fraction 13, 14 is also drawn off or introduced. At least a part of the energy required for the compression of the heated gas fraction 31 is formed by the mechanical energy generated during the relaxation 36; For this purpose, the expansion machine 36 and the compressor 32 are preferably coupled mechanically. In certain cases, the compression 32 can be omitted; then it is sufficient to warm the gas fraction 30 only up to a medium temperature and then to supply it directly via line 35 to the work relaxation 36.
In Figur 2 ist eine Variante des Verfahrens nach Figur 1 dargestellt, bei der außer Sauerstoff und Stickstoff auch Krypton und Xenon gewonnen werden. Dazu sind weitere Verfahrensschritte und Einrichtungen zur Krypton-/Xeπongewinnung vorgesehen, die sich außerhalb des Rektifiziersystems zur Stickstoff-Sauerstoff- Trennung befinden. Diese können sich jeder der bekannten Methoden zur Krypton- /Xenongewinnung aus einer an diesen Komponenten angereicherten Sauerstofffraktioπ bedienen, insbesondere der oben erwähnten. Als üblicher Einsatz für das System 202 zur Krypton-/Xenongewinnung dient die Sauerstofffraktion 24, die aus dem Sumpf der Niederdrucksäule abgezogen wird. Zusätzlich wird bei dem erfindungsgemäßen Verfahren die gereinigte Spülfraktion stromabwärts der Reinigungsstufe 17 teilweise oder vollständig über Leitung 201 dem System 202 zur Krypton-/Xenongewιnnung zugeführt, und zwar vorzugsweise im flüssigen Zustand. Sie kann insbesondere an geeigneter Stelle in eine Austauschsäule eingespeist werden, die zur Erzeugung eines krypton- und xenonhaltigen, aber sauerstofffreien Gemischs dient, oder in eine andere Säule zur Voranreicherung von Krypton und/oder Xenon. Die Einspeisestelle liegt unterhalb des Kopfs der entsprechenden Säule.FIG. 2 shows a variant of the method according to FIG. 1, in which krypton and xenon are obtained in addition to oxygen and nitrogen. For this purpose, further process steps and devices for krypton / xenon extraction are provided, which are located outside the rectification system for nitrogen-oxygen separation. These can use any of the known methods for obtaining krypton / xenon from an oxygen fraction enriched in these components, in particular the one mentioned above. Oxygen fraction 24, which is drawn off from the bottom of the low-pressure column, serves as a common use for system 202 for krypton / xenon extraction. In addition, in the method according to the invention, the cleaned rinsing fraction downstream of the cleaning stage 17 is partly or completely fed via line 201 to the system 202 for krypton / xenon extraction, preferably in the liquid state. It can in particular be fed at a suitable point into an exchange column which is used to produce a krypton- and xenone-containing but oxygen-free mixture, or into another column for the pre-enrichment of krypton and / or xenon. The feed point is below the head of the corresponding column.
Bei dem Ausfuhrungsbeispiel von Figur 3 wird eine Zwischenfraktion 340 in Höhe des Abzugs der sauerstoffaπgereicherten Fraktion 13 oder höher in flüssiger Form aus der Drucksaule 6 entnommen Sie wird durch eine Pumpe 341 flüssig auf einen erhöhten Druck von beispielsweise 7 bar gebracht und anschließend über Leitung 342 dem Hauptwarmetauscher 4 zugeführt. Dort wird sie unter dem erhöhten Druck verdampft und auf eine Zwischentemperatur angewärmt. Die angewärmte Zwischenfraktion wird über Leitung 335 einer Entspannungsmaschine 336 zugeleitet Stromabwarts der arbeitsleistenden Entspannung 336 wird sie über Leitung 337 der Niederdrucksaule 7 an einer Zwischeπstelle zugeführt oder als Produkt abgeführtIn the exemplary embodiment of FIG. 3, an intermediate fraction 340 in the amount of the withdrawal of the oxygen-enriched fraction 13 or higher in liquid form is removed from the pressure column 6. It is brought to an increased pressure of, for example, 7 bar in liquid form by a pump 341 and then via line 342 to the Main heat exchanger 4 supplied. There it is evaporated under the increased pressure and warmed to an intermediate temperature. The warmed intermediate fraction will Via line 335 fed to a relaxation machine 336 Downstream of the work-relieving relaxation 336, it is fed via line 337 to the low-pressure column 7 at an intermediate point or discharged as a product
Als Wärmequelle für die Verdampfung der arbeitsleistend zu entspannendenAs a heat source for the evaporation of work to be relaxed
Zwischenfraktion 342 dient ein Heizmittel, das über Leitung 330 gasformig von einer Zwischenstelle (alternativ vom Kopf) der Drucksaule 6 entnommen und im Hauptwarmetauscher 4 angewärmt wird Das angewärmte Heizmittel 331 wird in einem Verdichter 332 beispielsweise auf 8 bar kompπmiert und nach Nachkuhlung 333 wieder dem Hauptwarmetauscher 4 zugeführt (Leitung 334) Dort wird es abgekühlt und schließlich mindestens teilweise kondensiert Das kondensierte Heizmittel 343 wird wieder in die Drucksaule entspannt vorzugsweise an der Stelle seiner Entnahme über Leitung 330 oder etwas hoherIntermediate fraction 342 is a heating medium, which is taken out in gaseous form via line 330 from an intermediate point (alternatively from the head) of the pressure column 6 and heated in the main heat exchanger 4. The heated heating medium 331 is compressed in a compressor 332, for example, to 8 bar and, after cooling 333, is returned to the main heat exchanger 4 fed (line 334) There it is cooled and finally at least partially condensed. The condensed heating medium 343 is expanded back into the pressure column, preferably at the point of its removal via line 330 or somewhat higher
Mindestens ein Teil der für die Verdichtung des angewärmten Heizmittels 331 benotigten Energie wird durch die bei der arbeitsleistenden Entspannung 336 erzeugte mechanische Energie gebildet, vorzugsweise werden dazu die Entspannungsmaschine 336 und der Verdichter 332 mechanisch gekoppeltAt least a part of the energy required for the compression of the heated heating means 331 is generated by the mechanical energy generated during the work-relieving expansion 336, preferably the expansion machine 336 and the compressor 332 are mechanically coupled for this purpose
In dem in der Zeichnung dargestellten Beispiel liegen die Entnahmestellen der arbeitsleistend zu entspannenden Zwischenfraktion und des Heizmittels auf derselben Hohe, und zwar auf derjenigen des Abzugs der sauerstoffangereicherten Fraktion 13 Sie konnten ebenso auf verschiedenen Hohen liegen, beispielsweise ist es möglich beide an verschiedenen Stellen oberhalb der Entnahme der sauerstoffangereicherten Fraktion 13 anzuordnen Dadurch verschieben sich auch die Einspeisestelleπ in Niederdrucksaule und DrucksauleIn the example shown in the drawing, the tapping points of the intermediate fraction to be relaxed for work and the heating medium are at the same level, namely at that of the deduction of the oxygen-enriched fraction 13. They could also be at different levels, for example it is possible for both to be at different points above the Removal of the oxygen-enriched fraction 13 to be arranged. This also shifts the feed point in the low-pressure column and the pressure column
Das in Figur 4 schematisch dargestellte Verfahren dient zur Gewinnung von gasformigem Sauerstoff unter erhöhtem Druck durch Innenverdichtung Dazu wird flussiger Sauerstoff 423 aus der Niederdrucksaule 7 in einer Pumpe 452 auf einen erhöhten Druck von beispielsweise 9 bar gebracht Die Flüssigkeit 453 wird unter dem hohen Druck dem Hauptwarmetauscher 4 zugeführt und dort verdampft und angewärmt Über Leitung 422 wird das gasformige Druckprodukt abgezogen Als Heizfluid für die Verdampfung des flüssigen Sauerstoffs 453 dient eine Zwischenfraktion die über Leitung 430 gasformig von einer Zwischenstelle (alternativ vom Kopf) der Drucksaule 6 entnommen und im Hauptwarmetauscher 4 angewärmt wird Das angewärmte Heizfluid 431 wird in einem mittels externer Energie angetπebenen Verdichter 432 auf beispielsweise 20 bar kompπmiert und nachThe process shown schematically in FIG. 4 serves to obtain gaseous oxygen under increased pressure by internal compression. For this purpose, liquid oxygen 423 from the low-pressure column 7 is brought to an increased pressure of, for example, 9 bar in a pump 452. The liquid 453 is brought to the main heat exchanger under the high pressure 4 fed and evaporated and heated there via line 422, the gaseous printed product is withdrawn An intermediate fraction serves as heating fluid for the evaporation of the liquid oxygen 453, which is taken out in gaseous form via line 430 from an intermediate point (alternatively from the head) of the pressure column 6 and is heated in the main heat exchanger 4 20 bar compressed and after
Nachkuhlung 433 wieder dem Hauptwarmetauscher 4 zugeführt (Leitung 454) Dort wird es abgekühlt und mindestens teilweise kondensiert Das kondensierte Heizfluid 455 wird wieder in die Drucksaule eingedrosselt, vorzugsweise an der Stelle seiner Entnahme über Leitung 430 oder etwas hoher Ein Teil 434 der im Verdichter 432 kompπmierten Zwischenfraktion 430/431 aus der Drucksaule kann für dieAfter-cooling 433 is again fed to the main heat exchanger 4 (line 454), where it is cooled and at least partially condensed. The condensed heating fluid 455 is throttled back into the pressure column, preferably at the point of its removal via line 430 or somewhat higher part 434 of those compressed in the compressor 432 Intermediate fraction 430/431 from the pressure column can be used for the
Kaltegewinnung eingesetzt werden, indem er bei einer Zwischentemperatur aus dem Hauptwarmetauscher entnommen (Leitung 35) und einer Entspanπungsmaschine 36 zugeführt wird Die arbeitsleistend entspannte Fraktion wird über Leitung 37 stromabwärts der arbeitsleistenden Entspannung 36 der Niederdrucksaule 7 an einer Zwischenstelle zugeführt Alternativ dazu kann sie über die gestπchelt dargestellte Leitung 451 in die Drucksaule 6 zuruckgeleitet werdenCold production can be used by removing it from the main heat exchanger at an intermediate temperature (line 35) and feeding it to a decompression machine 36. The fraction that is relaxed for work is fed via line 37 downstream of the work-related expansion 36 to the low-pressure column 7 at an intermediate point. Alternatively, it can be pricked Line 451 shown are returned to the pressure column 6
Die Varianten der Figuren 3 und 4 können mit der Kryptoπ-/Xenon-Gewιnnung nach Figur 2 kombiniert werden The variants of FIGS. 3 and 4 can be combined with the crypto / xenon extraction according to FIG. 2

Claims

Patentansprücheclaims
Verfahren zur Tieftemperaturzeriegung von Luft, bei dem verdichtete und vorgereinigte Einsatziuft (3, 5) in ein Rektifiziersystem zur Stickstoff-Sauerstoff- Trennung eingeleitet wird, das eine Drucksaule (6) aufweist, wobei mindestens ein Teil der verdichteten und vorgereinigten Einsatzluft der Drucksaule (6) zugespeist (5) wird, eine sauerstoffangereicherte Fraktion (13) der Drucksaule (6) entnommen und einem weiteren Arbeitsschπtt (7) innerhalb des Rektifiziersystems zugeleitet (14) wird, die sauerstoffangereicherte Fraktion (13) mindestens einen theoretischen oder praktischen Boden (15) oberhalb der Stelle entnommen wird, an der verdichtete und vorgereinigte Einsatzluft (5) derMethod for low-temperature air extraction, in which compressed and pre-cleaned feed air (3, 5) is introduced into a rectification system for nitrogen-oxygen separation, which has a pressure column (6), at least part of the compressed and pre-cleaned feed air of the pressure column (6 ) is fed (5), an oxygen-enriched fraction (13) is removed from the pressure column (6) and is fed (14) to a further work step (7) within the rectification system, the oxygen-enriched fraction (13) has at least one theoretical or practical base (15) is removed above the point at which the compressed and pre-cleaned feed air (5)
Drucksauie zugespeist wird, und wobei vom Sumpf der Drucksaule (6) eine Spulfraktion (16) flussig abgeführt, in flussigem Zustand einer ReinigungsstufeDrucksauie is fed, and wherein from the bottom of the pressure column (6) a coil fraction (16) is removed in liquid form, in the liquid state of a cleaning stage
(17) zugeführt, in der N20 entfernt wird, und als gereinigte Spulfraktion (18) der Reinigungsstufe (17) entnommen wird(17) supplied, in which N 2 0 is removed, and is removed from the cleaning stage (17) as the purified winding fraction (18)
Verfahren nach Anspruch 1 , bei dem N2O in der Reinigungsstufe (17) durch physikalische Adsorption aus der Spulfraktion (16) entfernt wirdA method according to claim 1, in which N 2 O is removed from the winding fraction (16) by physical adsorption in the cleaning stage (17)
Verfahren nach Anspruch 1 oder 2, bei dem die Spulfraktion in der Reinigungsstufe durch indirekten Wärmeaustausch verdampft wird, wobei bei derThe method of claim 1 or 2, wherein the winding fraction is evaporated in the cleaning stage by indirect heat exchange, wherein in the
Verdampfung N20 als Feststoff und/oder Flüssigkeit ausfalltEvaporation N 2 0 fails as a solid and / or liquid
Verfahren nach einem der Ansprüche 1 bis 3, bei dem N20 in der Reinigungsstufe durch Gegenstrom-Stoffaustausch aus der Spulfraktion entferntMethod according to one of Claims 1 to 3, in which N 2 0 is removed from the winding fraction in the cleaning stage by countercurrent mass transfer
Verfahren nach einem der Ansprüche 1 bis 4, bei dem die gereinigte SpulfraktionMethod according to one of claims 1 to 4, wherein the purified winding fraction
(18) mindestens teilweise einem System (202) zur Gewinnung von Krypton und/oder Xenon zugeführt wird(18) is at least partially fed to a system (202) for obtaining krypton and / or xenon
Verfahren nach einem der Ansprüche 1 bis 5 bei dem die gesamte Einsatzluft (1 3 5), die in dem Rektifiziersystem zerlegt wird in die Drucksaule (6) eingeleitet Verfahren nach einem der Ansprüche 1 bis 6 bei dem der Drucksaule (6) eine Zwischeπfraktion (30 340, 430) mindestens einen theoretischen oder praktischen Boden oberhalb der Stelle entnommen wird, an der verdichtete und vorgereinigte Einsatziuft zugespeist (5) wird, und diese Zwischeπfraktion (30, 31 , 34, 35, 340,Method according to one of Claims 1 to 5, in which the entire feed air (1 3 5) which is broken down in the rectification system is introduced into the pressure column (6) Method according to one of Claims 1 to 6, in which an intermediate fraction (30 340, 430) is removed from the pressure column (6) at least one theoretical or practical base above the point at which compressed and pre-cleaned feed air is fed (5), and this intermediate fraction (30, 31, 34, 35, 340,
342, 335 430, 431 , 434, 35) arbeitsleistend entspannt (36, 336) wird342, 335 430, 431, 434, 35) work-relaxed (36, 336)
Verfahren nach Anspruch 7, bei dem die Zwischenfraktion stromaufwärts der arbeitsleistenden Entspannung (336) in flussigem Zustand aus der Drucksaule (6) abgezogen (340), im flussigen Zustand einer Druckerhohung (341) unterworfen, durch indirekten Wärmeaustausch (4) verdampft und angewärmt wirdMethod according to Claim 7, in which the intermediate fraction upstream of the work-relieving expansion (336) is withdrawn (340) in a liquid state from the pressure column (6), is subjected to a pressure increase (341) in the liquid state, is evaporated and heated by indirect heat exchange (4)
Verfahren nach einem der Ansprüche 1 bis 8, bei dem ein Produktstrom (423) flussigem Zustand auf Druck gebracht (452), gegen ein unter hohem Druck stehendes Heizfluid (454) verdampft und als Druckprodukt (422) abgeführt wird, wobei als Heizfluid eine Gasfraktion (430, 431 , 454) eingesetzt wird, die der Drucksaule (6) mindestens einen theoretischen oder praktischen Boden oberhalb der Stelle entnommen (430) wird, an der verdichtete und vorgereinigte Einsatziuft zugespeist (5) wirdMethod according to one of Claims 1 to 8, in which a product stream (423) in a liquid state is pressurized (452), evaporated against a high-pressure heating fluid (454) and discharged as a printed product (422), a gas fraction being used as the heating fluid (430, 431, 454) is used, which is taken from the pressure column (6) at least one theoretical or practical base above the point (430), at which compressed and pre-cleaned application air is fed (5)
Verfahren nach einem der Ansprüche 1 bis 9, bei dem ein Teil der Sumpfflussigkeit der Drucksaule verdampft und das dabei entstandene Gas in die Drucksaule zuruckgeleitet wirdMethod according to one of claims 1 to 9, in which a part of the bottom liquid of the pressure column evaporates and the gas formed in the process is returned to the pressure column
Vomchtung zur Tieftemperaturzeriegung von Luft mit einem Rektifiziersystem zur Stickstoff-Sauerstoff-Trennung, das mindestens eine Drucksaule (6) aufweist, mit einer Einsatzleitung (1 3, 5) zur Einleitung von verdichteter und vorgereinigter Einsatziuft in die Drucksauie (6), mit einer Rohsauerstoffleitung (13, 14) für eine sauerstoffangereicherte Fraktion die einerseits mit der Drucksaule (6) und andererseits mit einer weiteren Vomchtung (7) innerhalb des demDevice for the low-temperature extraction of air with a rectification system for nitrogen-oxygen separation, which has at least one pressure column (6), with an insert line (1 3, 5) for introducing compressed and pre-cleaned inlet air into the pressure line (6), with a raw oxygen line (13, 14) for an oxygen-enriched fraction which on the one hand with the pressure column (6) and on the other hand with another device (7) within the
Rektifiziersystems zur Stickstoff-Sauerstoff-Trennung verbunden ist mit einer Spulflussigkeitsleitung (16) die mit dem Sumpf der Drucksaule (6) und mit einer Reinigungseinrichtung (17) zur Entfernung von N20 verbunden !st und mit einem Stoffaustauscnabschnitt (15) im Umfang mindestens eines theoretischen oder praktischen Bodens, der in der Drucksaule (6) zwischen der Rohsauerstoffleitung (13) und dem Sumpf angeordnet istRectification system for nitrogen-oxygen separation is connected to a coil liquid line (16) which is connected to the sump of the pressure column (6) and to a cleaning device (17) for removing N 2 0 ! st and with a substance exchange section (15) to the extent of at least one theoretical or practical soil, which is arranged in the pressure column (6) between the raw oxygen line (13) and the sump
Vomchtung nach Anspruch 11 , bei der die Drucksaule durch zwei voneinander getrennte Abschnitte realisiert ist, der erste Abschnitt (Vorsaule) mit derThe device according to claim 11, wherein the pressure column is realized by two separate sections, the first section (guard column) with the
Einsatzluftleitung und der Spulflussigkeitsleitung verbunden ist und mindestens einen Teil des Stoffaustauschabschnitts zwischen Rohsauerstoffleitung und Sumpf der Drucksaule enthalt, wobei eine Gasleitung den Kopf des ersten Abschnitts mit dem unteren Bereich des zweiten Abschnitts (Hauptsaule) verbindet und der zweite Abschnitt mit der Rohsauerstoffleitung verbunden ist Feed air line and the purge liquid line is connected and contains at least a part of the mass transfer section between the raw oxygen line and the sump of the pressure column, wherein a gas line connects the head of the first section to the lower region of the second section (main column) and the second section is connected to the raw oxygen line
EP99939452A 1998-08-06 1999-08-05 Method and device for cryogenic air separation Expired - Lifetime EP1102954B1 (en)

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DE19835474 1998-08-06
DE19835474 1998-08-06
DE19852020A DE19852020A1 (en) 1998-08-06 1998-11-11 Method and device for the low-temperature separation of air
DE19852020 1998-11-11
EP98123463 1998-12-11
EP98123463A EP0978699A1 (en) 1998-08-06 1998-12-11 Process and apparatus for the cryogenic separation of air
PCT/EP1999/005678 WO2000008399A1 (en) 1998-08-06 1999-08-05 Method and device for cryogenic air separation
EP99939452A EP1102954B1 (en) 1998-08-06 1999-08-05 Method and device for cryogenic air separation

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EP0978699A1 (en) 2000-02-09
DE19852020A1 (en) 2000-02-10
ES2188211T3 (en) 2003-06-16
ATE228637T1 (en) 2002-12-15
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AU5373799A (en) 2000-02-28
CN1171065C (en) 2004-10-13

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