JP4577977B2 - Air liquefaction separation method and apparatus - Google Patents

Air liquefaction separation method and apparatus Download PDF

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Publication number
JP4577977B2
JP4577977B2 JP2000346409A JP2000346409A JP4577977B2 JP 4577977 B2 JP4577977 B2 JP 4577977B2 JP 2000346409 A JP2000346409 A JP 2000346409A JP 2000346409 A JP2000346409 A JP 2000346409A JP 4577977 B2 JP4577977 B2 JP 4577977B2
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distillation
passage
argon
liquefied
gas
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JP2002147949A (en
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信明 江越
博志 橘
浩 川上
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Taiyo Nippon Sanso Corp
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Taiyo Nippon Sanso Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04642—Recovering noble gases from air
    • F25J3/04648—Recovering noble gases from air argon
    • F25J3/04654—Producing crude argon in a crude argon column
    • F25J3/0466—Producing crude argon in a crude argon column as a parallel working rectification column or auxiliary column system in a single pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04048—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams
    • F25J3/04054—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams of air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—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
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    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04296—Claude expansion, i.e. expanded into the main or high pressure column
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
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    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04309—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04351—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04624—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 integrated mass and heat exchange, so-called non-adiabatic rectification, e.g. dephlegmator, reflux exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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
    • F25J3/04951—Arrangements of multiple air fractionation units or multiple equipments fulfilling the same process step, e.g. multiple trains in a network
    • F25J3/04963—Arrangements of multiple air fractionation units or multiple equipments fulfilling the same process step, e.g. multiple trains in a network and inter-connecting equipment within or downstream of the fractionation unit(s)
    • 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
    • F25J5/00—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants
    • F25J5/002—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants for continuously recuperating cold, i.e. in a so-called recuperative heat exchanger
    • F25J5/007—Arrangements of cold exchangers or cold accumulators in separation or liquefaction plants for continuously recuperating cold, i.e. in a so-called recuperative heat exchanger combined with mass exchange, i.e. in a so-called dephlegmator
    • 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
    • F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/24—Multiple compressors or compressor stages in parallel
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    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/40—Processes or apparatus involving steps for increasing the pressure of gaseous process streams the fluid being air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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")

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

Description

【０００１】
【発明の属する技術分野】
本発明は、空気液化分離方法及び装置に関し、詳しくは、熱交換型蒸留器を利用して空気を低温液化蒸留することにより、空気から窒素、アルゴン、酸素等を製品として採取する空気液化分離方法及び装置に関する。
【０００２】
【従来の技術】
現在、空気を低温蒸留することによって窒素、アルゴン、酸素等を生産するには，一般に、高圧塔と低圧塔とからなる複式蒸留塔と、低圧塔にサイドカラムとして接続されるアルゴン塔との計３つの蒸留塔からなる空気液化分離装置が使用されている．しかし近年は、時代の要求により、動力消費量の低減とともに、装置の小型化がますます強く要求されており、その目的のために熱交換型蒸留器を利用した方法、装置が提案されている。
【０００３】
例えば、特許第２８３３５９４号公報には、中純度酸素（８５〜９９％）の製造方法が開示されている。ここでは、二組の通路を有するプレートフィン熱交換器を熱交換型蒸留器として使用し、その一組の通路において原料空気ガスを蒸留し、該通路の上部に窒素に富む生成物を、下部に酸素に富む生成物を分離するとともに、他の一組の通路において、酸素に富んだ液を原料としてストリッピングを行い、上部に窒素に富む生成物を、下部に酸素をそれぞれ分離し、下部から製品として酸素を得るようにしている。
【０００４】
また、特開平１１−１５３３８３号公報には、熱交換型蒸留器を用いて動力消費量を最大限制限しつつ、小型化を図りながら高純度窒素ガスを製造する方法及び装置が開示されている。ここでは、三通路式の熱交換型蒸留器が用いられ，蒸留通路の下部では空気還流液がリボイルされ、上部では窒素に富むガスの分縮が行われ、これにより小型化が可能であることが示されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、このような蒸留塔と熱交換型蒸留器との組合わせにおいて、その消費動力の低減及び装置の小型化は、未だ不十分であり、さらに、これまで熱交換型蒸留器を用いて製造される製品は、窒素と酸素とに限られており、窒素、酸素及びアルゴンを採取することが求められている。
【０００６】
そこで本発明は、蒸留塔で分離した窒素ガスを熱交換型蒸留器の熱媒体として利用することにより、消費動力の削減及び装置の小型化を図りながら、製品として窒素や酸素だけでなくアルゴンも採取することができ、また、前記窒素ガスを循環使用することによって消費動力の更なる削減を図ることができる空気液化分離方法及び装置を提供することを目的としている。
【０００７】
【課題を解決するための手段】
上記目的を達成するため、本発明の空気液化分離方法は、圧縮、精製、冷却した原料空気を蒸留塔に導入し、該蒸留塔で低温蒸留することによって塔上部の窒素ガスと塔下部の窒素を含む粗液化酸素とに分離した後、蒸留塔から導出した前記粗液化酸素を熱交換型蒸留器の蒸留通路に下降液として導入するとともに、前記蒸留塔から導出した窒素ガスを昇温し、その一部を昇圧した後、再度冷却してから前記熱交換型蒸留器の凝縮通路に下降ガスとして導入し、前記蒸留通路内の流体との熱交換により凝縮させて液化窒素とし、該液化窒素を減圧してから前記蒸留塔の還流液とし、該窒素ガスと前記粗液化酸素とを熱交換させることにより前記液化酸素の一部を気化させて上昇ガスとし、該蒸留通路内で上昇ガスと下降液とを気液接触させることによって該蒸留通路の上部に酸素を含む窒素ガスを、該蒸留通路の下部に液化酸素をそれぞれ分離し、該液化酸素を製品酸素として採取することを特徴としている。
【０００８】
さらに、本発明の空気液化分離方法は、圧縮、精製、冷却した原料空気を蒸留塔に導入し、該蒸留塔で低温蒸留することによって塔上部の窒素ガスと塔下部の窒素を含む粗液化酸素とに分離した後、蒸留塔から導出した前記粗液化酸素を熱交換型蒸留器の蒸留通路に下降液として導入するとともに、前記蒸留塔から導出した前記窒素ガスを前記熱交換型蒸留器の凝縮通路に下降ガスとして導入し、該窒素ガスと前記粗液化酸素とを熱交換させることにより前記液化酸素の一部を気化させて上昇ガスとし、該蒸留通路内で上昇ガスと下降液とを気液接触させることによって該蒸留通路の上部に酸素を含む窒素ガスを、該蒸留通路の下部に液化酸素をそれぞれ分離し、該液化酸素を製品酸素として採取し、蒸留塔から液状の粗液化アルゴンとして導出し、前記熱交換型蒸留器の蒸留通路に下降液として導入し、前記凝縮通路の窒素ガスとの熱交換により粗液化アルゴンの一部を気化させて上昇ガスとし、該蒸留通路内で上昇ガスと下降液とを気液接触させることによって該蒸留通路の上部にアルゴンを含む窒素ガスを、該蒸留通路の下部に液化アルゴンをそれぞれ分離し、該液化アルゴンを製品アルゴンとして採取するとともに、上部のアルゴンを含む窒素ガスを前記蒸留塔に再導入することを特徴としている。
【０００９】
また、本発明方法においては、前記熱交換型蒸留器の凝縮通路に、前記窒素ガスに代えて冷却後の原料空気の一部を下降ガスとして導入することもできる。
【００１０】
さらに、前記蒸留通路から導出した液化酸素を昇圧してから気化させることにより、高圧の製品酸素ガスを得ることができる。運転に必要な寒冷は、原料空気、分離ガスの少なくともいずれか一部を断熱膨張させることによって得ることができ、この断熱膨張で発生する膨張仕事を利用して前記原料空気を二次圧縮することもできる。
【００１１】
加えて、前記蒸留塔から粗液化アルゴンを導出するのに代えてガス状の粗アルゴンガスとして導出し、該導出した粗アルゴンガスをアルゴン蒸留塔に導入して更に低温蒸留することにより窒素ガスと粗液化アルゴンとに分離し、分離した粗液化アルゴンを前記熱交換型蒸留器の蒸留通路に下降液として導入することもできる。
【００１２】
また、本発明の空気液化分離装置は、原料空気を圧縮する原料空気圧縮機と、圧縮された原料空気中に含まれる水分や二酸化炭素等の低温で固化する不純物を除去する精製器と、精製された原料空気を冷却する主熱交換器と、冷却された原料空気を低温蒸留して窒素ガスと粗液化酸素とに分離する蒸留塔と、蒸留通路及び凝縮通路を有する熱交換型蒸留器とを備え、該熱交換型蒸留器は、前記蒸留塔で分離した前記粗液化酸素を前記蒸留通路に下降液として導入する経路と、該蒸留通路で前記凝縮通路を流れる流体との熱交換により気化して該蒸留通路の上部に上昇した酸素を含む窒素ガスを導出する経路と、該蒸留通路の下部に下降した液化酸素を製品酸素として導出する経路と、前記蒸留塔の上部から導出した窒素ガスの一部を前記主熱交換器に導入する経路と、該主熱交換器で加温された窒素ガスを導出して循環窒素圧縮機に導入する経路と、該循環窒素圧縮機で圧縮した圧縮窒素ガスを前記主熱交換器に導入する経路と、該主熱交換器で冷却された圧縮窒素ガスを導出して前記熱交換器型蒸留器の凝縮通路に下降ガスとして導入する経路と、該凝縮通路で前記蒸留通路を流れる酸素との熱交換により液化して該凝縮通路の下部に下降した液化窒素を導出して減圧後に前記蒸留塔の上部に還流液として導入する経路とを備えていることを特徴としている。
【００１３】
さらに、本発明の空気液化分離装置は、前記蒸留塔で原料空気を低温蒸留する際に塔中部に生成する窒素を含む粗アルゴンを該蒸留塔から液状の粗液化アルゴンとして導出し、前記熱交換型蒸留器の蒸留通路の一部に下降液として導入する経路と、該蒸留通路で前記凝縮通路を流れる流体との熱交換により気化して該蒸留通路の上部に上昇したアルゴンを含む窒素ガスを導出する経路と、該蒸留通路の下部に下降した液化アルゴンを製品アルゴンとして採取する経路とを設けたことを特徴としている。
【００１４】
また、粗液化アルゴンを前記蒸留通路に導入する手段として、粗アルゴンガスを低温蒸留して窒素ガスと粗液化アルゴンとに分離するアルゴン蒸留塔を設け、該アルゴン蒸留塔に、前記蒸留塔の塔中部に生成した粗アルゴンをガス状の粗アルゴンガスとして導出し、該アルゴン蒸留塔に導入する経路と、該アルゴン蒸留塔で分離した窒素ガスを導出する経路と、分離した粗液化アルゴンを前記蒸留通路に下降液として導入する経路とを採用することができる。
【００１５】
さらに、前記蒸留通路の下部に気液分離器を設けたこと、前記蒸留塔から導出した粗液化酸素を前記熱交換型蒸留器の蒸留通路に供給する液化酸素供給ポンプを備えていること、前記熱交換型蒸留器の蒸留通路から導出した液化酸素を昇圧する液化酸素昇圧ポンプを備えていることを特徴としている。
【００１６】
また、前記凝縮通路に、窒素に代えて、冷却後の原料空気の一部を前記凝縮通路に下降ガスとして導入する経路と、該凝縮通路で前記蒸留通路を流れる流体との熱交換により液化して該凝縮通路の下部に下降した液化空気を導出する経路とを設けることができる。
【００１８】
また、前記主熱交換器の途中から前記昇圧窒素ガスの一部を分岐して膨張タービンに導入する経路と、該膨張タービンで断熱膨張して寒冷を発生した低温窒素ガスを前記主熱交換器に導入する経路とを備えていることを特徴とし、前記主熱交換器の途中から原料空気を導出する経路と、該経路に導出した原料空気を低温圧縮する二次空気圧縮機を設けるとともに、該二次空気圧縮機を、前記膨張タービンでの断熱膨張で発生する膨張仕事、あるいは、該二次空気圧縮機で低温圧縮された高圧原料空気を断熱膨張させる空気膨張タービンでの断熱膨張で発生する膨張仕事を利用して駆動することを特徴としている。
【００１９】
【発明の実施の形態】
図１は本発明の空気液化分離装置の第１形態例を示す系統図、図２は本発明で使用する熱交換型蒸留器の一形態例を示す一部断面斜視図である。
【００２０】
この空気液化分離装置は、原料空気を圧縮する原料空気圧縮機１と、圧縮空気の圧縮熱を取り除く空気予冷器２と、圧縮された原料空気中に含まれる水分や二酸化炭素等の低温で固化する不純物を除去する精製器３と、精製された原料空気を低温蒸留で得られた流体との熱交換により冷却する主熱交換器４と、冷却された原料空気を低温蒸留する蒸留塔５と、酸素用の蒸留通路（酸素蒸留通路）６１、アルゴン用の蒸留通路（アルゴン蒸留通路）６２及び窒素用の凝縮通路（窒素凝縮通路）６３を有する熱交換型蒸留器６と、窒素循環経路を形成する循環窒素圧縮機７と、寒冷を発生する膨張タービン８とを主要な構成機器としており、低温仕様の機器は、保冷槽９内に収納されている。
【００２１】
前記熱交換型蒸留器６における酸素蒸留通路６１及びアルゴン蒸留通路６２は、窒素凝縮通路６３に対してそれぞれ熱交換関係にあり、酸素蒸留通路６１及びアルゴン蒸留通路６２が被加温側、窒素凝縮通路６３が被冷却側となっている。なお、図１においては、図の簡略化のために各通路６１，６２，６３を１本の線で示しているが、実際の熱交換型蒸留器６は、図２に示すような形態となっている。
【００２２】
図２に示す熱交換型蒸留器６は、プレートフィン式熱交換器１０を熱交換型蒸留器６として使用したものであって、鉛直方向に設置した多数の仕切板１１によって蒸留通路１２と凝縮通路１３とを交互に積層し、熱交換器上部には、蒸留通路１２に粗液化酸素又は粗液化アルゴンを導入する蒸留通路液導入ヘッダー１４及び蒸留通路１２内で気化したガスを導出する蒸留通路ガス導出ヘッダー１５を、熱交換器下部には、蒸留通路１２内を下降した液（液化酸素、液化アルゴン）を導出する蒸留通路液導出ヘッダー１６を、それぞれ蒸留通路１２に連通するようにして設けるとともに、熱交換器側面上部には、凝縮通路１３に窒素ガスを導入する凝縮通路ガス導入ヘッダー１７を、下部には凝縮通路１３で液化した液化窒素を導出する凝縮通路液導出ヘッダー１８を、それぞれ凝縮通路１３に連通するようにして設けている。また、蒸留通路１２の上部には、各蒸留通路１２内へ液を均等に流下させるための液ディストリビューター１９が設けられ、酸素側とアルゴン側とは仕切板１１と直交する壁板１１ａによって区切られている。さらに、これらの各ヘッダーには、後述の各経路を構成する配管がそれぞれ接続されている。
【００２３】
以下、空気を深冷液化分離して窒素、酸素、アルゴンを得る手順を図１に基づいて説明する。まず、原料空気は、原料空気圧縮機１で所定の圧力に圧縮され、空気予冷器２で常温まで冷却された後、精製器３で原料空気中の水分や二酸化炭素等の不純物を吸着除去される。精製された原料空気は、経路２１から保冷槽９内に流入し、主熱交換器４で後述の製品ガスや排ガスからなる低温流体と熱交換して所定温度に冷却される。さらに、原料空気は、経路２２から過冷器２３を通り、経路２４を経て蒸留塔５の中下部に導入される。
【００２４】
蒸留塔５に導入された原料空気は、塔内を下降する還流液との気液接触により低沸点成分である窒素分を富化しながら上昇し、塔上部に窒素ガスが分離する。この窒素ガスは、蒸留塔５の上部から経路２５に導出され、過冷器２３、経路２６を経て主熱交換器４に導入され、昇温した後に経路２７から窒素ガスＧＮとして採取される。
【００２５】
一方、蒸留塔５内を流下する還流液は、塔内を上昇する上昇ガスとの気液接触により高沸点成分である酸素分を富化しながら流下し、塔下部に窒素分を含む粗液化酸素が分離する。この粗液化酸素は、蒸留塔５の下部から経路３１に導出され、液化酸素供給ポンプ３２で所定圧力に昇圧された後、経路３３を経て熱交換型蒸留器６の酸素蒸留通路６１に下降液として導入される。
【００２６】
酸素蒸留通路６１内を流下する粗液化酸素は、隣接する窒素凝縮通路６３を流れる流体、即ち窒素ガスと熱交換を行って加温され、粗液化酸素の一部が気化して酸素蒸留通路６１内を上昇する。このとき、粗液化酸素中の低沸点成分である窒素がより多く気化するので、酸素蒸留通路６１内を上昇する過程で下降液と気液接触を行い、窒素分を富化しながら酸素蒸留通路６１内を上昇して経路３４から導出される。この酸素を少量含む窒素ガスは、蒸留塔５の下部に戻されて上昇ガスとなる。
【００２７】
また、酸素蒸留通路６１内で気化せずに下降する流下液は、高沸点成分である酸素を富化しながら流下し、酸素蒸留通路６１の下部で液化酸素となる。この液化酸素は、経路３５に抜出されて気液分離器３６に導入され、気液分離された液化酸素が、経路３７から主熱交換器４を通って気化、昇温した後、経路３８から酸素ガスＧＯとして採取される。このとき、図１に破線で示すように、経路３８に液化酸素昇圧ポンプ３９を設け、該液化酸素昇圧ポンプ３９で昇圧してから主熱交換器４で気化させることにより、経路３８から高圧の製品酸素ガスを得ることができる。
【００２８】
また、熱交換型蒸留器６の窒素凝縮通路６３に導入される窒素ガスは、前記蒸留塔５の上部から経路２５に抜出した窒素ガスの一部を経路４１に分岐し、この窒素ガスを循環使用するようにしている。すなわち、経路４１に分岐した窒素ガスは、主熱交換器４で加温されて常温になり、経路４２を通って保冷槽９から導出され、前記循環窒素圧縮機７で所定圧力に圧縮される。この圧縮窒素ガスは、窒素予冷器４３で圧縮熱を除去された後、経路４４から再び保冷槽９内に導入され、主熱交換器４で再び所定温度に冷却される。冷却された圧縮窒素ガスは、経路４５を通って熱交換型蒸留器６の窒素凝縮通路６３に下降ガスとして導入され、隣接する酸素蒸留通路６１及びアルゴン蒸留通路６２を流れる流体と熱交換を行う。
【００２９】
このとき、窒素凝縮通路６３を流下する圧縮窒素ガスは、圧力を高くすることによって温度を高く設定し、窒素凝縮通路６３に隣接する酸素蒸留通路６１及びアルゴン蒸留通路６２を流れる粗液化酸素及び粗液化アルゴンよりも温度を高くしているので、粗液化酸素及び粗液化アルゴンを気化させるリボイルガス源として作用する。したがって、圧縮窒素ガスは、窒素凝縮通路６３を流下しながら、酸素蒸留通路６１及びアルゴン蒸留通路６２をそれぞれ流れる粗液化酸素及び粗液化アルゴンに熱を与えて気化させることにより、自身は冷却されて凝縮し、液化窒素となって窒素凝縮通路６３の下部から経路４６に流出する。経路４６の液化窒素は、過冷器２３を通って経路４７に導出し、減圧弁４８で蒸留塔５の操作圧力近くまで減圧した後、経路４９から蒸留塔５の上部に還流液として戻される。
【００３０】
また、前記経路４４から主熱交換器４に導入された圧縮窒素ガスの一部は、主熱交換器４の途中から経路５１に分岐して膨張タービン８に導入され、該膨張タービン８で断熱膨張することにより、装置の運転に必要な寒冷を発生する。寒冷を得た低温窒素ガスは、膨張タービン８から経路５２に導出し、前記経路２６の窒素ガスと合流して主熱交換器４に流入し、昇温した後に経路２７から導出される。
【００３１】
さらに、本形態例では、アルゴンを採取するため、蒸留塔５の中上部から経路７１に、略窒素とアルゴンとからなる粗液化アルゴンを導出し、熱交換型蒸留器６のアルゴン蒸留通路６２に下降液として導入している。この粗液化アルゴンは、前記粗液化酸素と同様に、隣接する窒素凝縮通路６３を流れる窒素ガスと熱交換を行い、一部が気化してアルゴン蒸留通路６２内を窒素分を富化しながら上昇し、アルゴンを少量含む窒素ガスとなって経路７２に導出され、蒸留塔５の中上部に戻されて上昇ガスとなる。
【００３２】
また、アルゴン蒸留通路６２内の流下液は、高沸点成分であるアルゴンを富化しながら流下し、液化アルゴンとなってアルゴン蒸留通路６２の下部から経路７３に抜出され、気液分離器７４を経て経路７５から製品液化アルゴンＬＡｒとして採取される。
【００３３】
図３は本発明の空気液化分離装置の第２形態例を示す系統図である。なお、以下の説明において、前記第１形態例の構成要素と同一の構成要素には同一の符号を付して詳細な説明は省略する。
【００３４】
本形態例では、蒸留塔５の中上部から略窒素とアルゴンとからなる粗アルゴンガスを経路８１に導出し、アルゴン蒸留塔８２に導入して窒素ガスと粗液化アルゴンとに分離し、塔下部に分離した粗液化アルゴンを経路８３から前記熱交換型蒸留器６のアルゴン蒸留通路６２に下降液として導入するとともに、該アルゴン蒸留通路６２を上昇したアルゴンを少量含む窒素ガスを経路８４からアルゴン蒸留塔８２の下部に上昇ガスとして戻すようにしている。また、アルゴン蒸留塔８２の上部には、前記経路４９から経路８５に分岐した液化窒素が還流液として導入され、塔上部に分離した窒素ガスは、経路８６に導出されて前記経路２５に合流する。
【００３５】
すなわち、アルゴン蒸留塔８２では、塔下部に上昇ガスとして導入された粗アルゴンガスと、塔上部に還流液として導入された液化窒素とによる低温蒸留が行われ、上昇ガスと還流液との気液接触により、上昇ガスは、低沸点成分である窒素が富化しながら塔内を上昇し、還流液は、高沸点成分であるアルゴンが富化しながら塔内を下降する。その結果、塔上部に窒素ガスが分離し、塔下部に粗液化アルゴンが分離することになる。
【００３６】
アルゴン蒸留塔８２からアルゴン蒸留通路６２に下降液として導入された粗液化アルゴンは、前記同様に、窒素凝縮通路６３を流れる窒素ガスにより加温されることにより、粗液化アルゴン中の低沸点成分である窒素がより多く気化し、気化したガスは、窒素分を富化しながらアルゴン蒸留通路６２を上昇してアルゴン蒸留塔８２に戻される。一方、気化しないでアルゴン蒸留通路６２を下降する液は、高沸点成分であるアルゴンを富化しながらアルゴン蒸留通路６２の下部に至り、経路７３、気液分離器７４、経路７５を経て製品液化アルゴンＬＡｒとして採取される。
【００３７】
図４は、本発明の空気液化分離装置の第３形態例を示す系統図である。本形態例において、精製器３で精製され、経路２１から主熱交換器４に導入された原料空気は、該主熱交換器４の途中から経路９１に導出された後、２個の二次空気圧縮機９２に導入されてそれぞれ所定圧力に低温圧縮される。低温圧縮された高圧原料空気は、経路９３を通って再び主熱交換器４に導入されて冷却された後、経路９４と経路９５とに分岐する。経路９４の高圧原料空気は、減圧弁９６で自由膨張して低温空気となった後、経路９７から過冷器２３を通り、経路２４を経て蒸留塔５に導入される。また、経路９５に分岐した高圧原料空気は、空気膨張タービン９８に導入され、断熱膨張して低温空気となり、経路９９に導出された後、前記経路９７の低温空気と合流して蒸留塔５に導入される。
【００３８】
さらに、前記循環窒素圧縮機７で圧縮された圧縮窒素ガスの一部が、経路４４から経路５３に分岐して膨張タービン８に導入され、断熱膨張して低温窒素ガスとなり、経路５４に導出される。この低温窒素ガスは、前記経路２６から主熱交換器４に導入された窒素ガスと主熱交換器４の途中で合流し、寒冷を回収されて経路２７から導出される。
【００３９】
そして、前記膨張タービン８及び空気膨張タービン９８での断熱膨張で発生する膨張仕事利用して前記二次空気圧縮機９２をそれぞれ駆動することにより、寒冷を有効に発生させることができるとともに、動力消費量を低減することができる。
【００４０】
ここで、前記熱交換型蒸留器６の酸素蒸留通路６１では、窒素凝縮通路６３を流れる窒素ガスから熱の供給を受けることにより、酸素蒸留通路６１に供給された粗液化酸素の一部が気化して上昇ガスを生成する。ここで生成した上昇ガスの量に対し、粗液化酸素の気化熱量と、窒素凝縮通路６３を流れる窒素ガスの液化熱量とが見合うようすることにより、窒素凝縮通路６３を流れる窒素ガスの流量が決まる。
【００４１】
このとき、窒素凝縮通路６３の窒素ガス流量は、上述のように窒素ガスを循環させることによって任意に設定することができるので、粗液化酸素の量も任意に設定することが可能となる。この粗液化酸素は、熱交換型蒸留器６の上部に下降液として供給されるので，酸素蒸留通路６１においては還流液に相当する。したがって、還流液量を任意に設定できることになり、還流比を大きくすることができ、酸素蒸留通路６１の内部還流比を増大することができる。さらに，従来の空気液化分離装置では、アルゴンを回収するため、アルゴン−酸素系の混合ガスを低圧塔からサイドカットしていたのに対し、本発明では、相対揮発度が大きい窒素・アルゴン系の混合流体を蒸留塔５からサイドカットできるので、アルゴン蒸留通路６２やアルゴン蒸留塔８２における蒸留を飛躍的に促進させることができる。これにより、装置の高さを低くして小型化した装置構成で窒素ガスと液化アルゴン及び酸素ガスを製品として効率的に回収することができる。
【００４２】
なお、各形態例では、蒸留塔５の下部から導出した粗液化酸素を液化酸素供給ポンプ３２で酸素蒸留通路６１に供給しているが、蒸留塔５と熱交換型蒸留器６との位置関係によっては、この液化酸素供給ポンプ３２を省略することができる。また、蒸留塔５への原料空気の導入位置も任意であり、塔下部に導入するようにしてもよい。さらに、熱交換型蒸留器６の凝縮通路６３には、窒素ガスに代えて原料空気の一部をリボイルガス源として導入することが可能であり、液化した空気は、蒸留塔５の適当な位置に下降液として導入することができる。
【００４３】
【実施例】
図１に示す構成の第１形態例装置を使用して窒素、酸素、アルゴンを採取する運転を行った。まず、原料空気圧縮機１で１７０ｋＰａまで圧縮した原料空気を、空気予冷器２で常温まで冷却し、精製器３で不純物を吸着除去した後、主熱交換器４で約−１９０℃の気液二相状態まで冷却してから蒸留塔５に導入した。蒸留塔５での低温蒸留の結果、塔上部からは、窒素濃度９９．９９％以上で、酸素含有量１ｐｐｂ以下窒素ガスが得られた。
【００４４】
そして、塔下部の粗液化酸素を、熱交換型蒸留器６の酸素蒸留通路６１の上部に下降液（還流液）として導入し、窒素凝縮通路６３を流れる循環窒素ガスと熱交換させて蒸留操作を行った。その結果、酸素蒸留通路６１の下部から、酸素純度９９．５％以上の液化酸素を得ることができた。このとき、窒素凝縮通路６３には、循環窒素圧縮機７で４９０ｋＰａに圧縮し、主熱交換器４で−１７９．６℃に冷却した循環窒素ガスを下降ガスとして導入した。
【００４５】
また、蒸留塔５の中上部から、アルゴン含有量２０％以上で、残部が略窒素である粗液化アルゴンをサイドカットし、熱交換型蒸留器６のアルゴン蒸留通路６２に下降液として導入し、窒素凝縮通路６３の窒素ガスと熱交換させた。その結果、アルゴン蒸留通路６２の下部から、純度９８％以上の液化アルゴンを回収することができた。
【００４６】
さらに、図３に示す第２形態例装置を使用した場合は、蒸留塔５の中上部から略窒素とアルゴン（含有量１０％以上）との粗アルゴンガスをサイドカットし、アルゴン蒸留塔８２の下部に導入して蒸留を行った。このアルゴン蒸留塔８２の上部からは、窒素濃度９９．９９％以上、酸素含有量１ｐｐｂ以下の窒素ガスが得られた。また、塔下部の粗液化アルゴンを熱交換型蒸留器６のアルゴン蒸留通路６２に下降液として導入した結果、アルゴン蒸留通路６２の下部から、純度９８％以上の液化アルゴンが得られた。
【００４７】
【発明の効果】
以上説明したように、本発明によれば、熱交換型蒸留器を使用した空気深冷液化分離法及び装置において、窒素、アルゴン及び酸素を製品として同時に採取することができる。また、同じ品質（純度，量，圧力）の製品を採取するための従来の規則充填蒸留塔を用いた空気分離装置における保冷槽の高さに比べて、本発明では、保冷槽の高さを約６５％にまで低減することができ、装置コストを大幅に削減することができる。
【図面の簡単な説明】
【図１】本発明の空気液化分離装置の第１形態例を示す系統図である。
【図２】本発明で使用する熱交換型蒸留器の一形態例を示す一部断面斜視図である。
【図３】本発明の空気液化分離装置の第２形態例を示す系統図である。
【図４】本発明の空気液化分離装置の第３形態例を示す系統図である。
【符号の説明】
１…原料空気圧縮機、２…空気予冷器、３…精製器、４…主熱交換器、５…蒸留塔、６…熱交換型蒸留器、７…循環窒素圧縮機、８…膨張タービン、９…保冷槽、１４…蒸留通路液導入ヘッダー、１５…蒸留通路ガス導出ヘッダー、１６…蒸留通路液導出ヘッダー、１７…凝縮通路ガス導入ヘッダー、１８…凝縮通路液導出ヘッダー、２３…過冷器、３２…液化酸素供給ポンプ、３６…気液分離器、３９…液化酸素昇圧ポンプ、６１…酸素蒸留通路、６２…アルゴン蒸留通路、６３…窒素凝縮通路、８２…アルゴン蒸留塔、９２…二次空気圧縮機、９６…減圧弁、９８…空気膨張タービン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air liquefaction separation method and apparatus, and more specifically, an air liquefaction separation method for collecting nitrogen, argon, oxygen, etc. from air as a product by low-temperature liquefaction distillation of air using a heat exchange distiller. And an apparatus.
[0002]
[Prior art]
Currently, in order to produce nitrogen, argon, oxygen, etc. by low-temperature distillation of air, generally, a double distillation column composed of a high-pressure column and a low-pressure column and an argon column connected as a side column to the low-pressure column are combined. An air liquefaction separation apparatus consisting of three distillation columns is used. However, in recent years, due to the demands of the times, there has been a strong demand for reduction in power consumption and downsizing of equipment, and a method and equipment using a heat exchange-type distiller have been proposed for that purpose. .
[0003]
For example, Japanese Patent No. 2833594 discloses a method for producing medium purity oxygen (85 to 99%). Here, a plate fin heat exchanger having two sets of passages is used as a heat exchange type distiller, the raw air gas is distilled in the one set of passages, and a nitrogen-rich product is placed in the upper portion of the passages. In the other set of passages, stripping is performed using an oxygen-rich liquid as a raw material to separate the nitrogen-rich product in the upper part and the oxygen in the lower part. I try to get oxygen as a product.
[0004]
Japanese Patent Application Laid-Open No. 11-153383 discloses a method and apparatus for producing high-purity nitrogen gas while minimizing the power consumption while limiting the power consumption to the maximum using a heat exchange type distiller. . Here, a three-pass heat exchange distiller is used, the air reflux is reboiled in the lower part of the distillation passage, and the nitrogen-rich gas is shrunk in the upper part, thereby enabling miniaturization. It is shown.
[0005]
[Problems to be solved by the invention]
However, in the combination of such a distillation column and a heat exchange type distiller, the reduction of the power consumption and the downsizing of the apparatus are still insufficient, and it has been produced using a heat exchange type distiller. Products to be produced are limited to nitrogen and oxygen, and it is required to collect nitrogen, oxygen and argon.
[0006]
Therefore, the present invention uses not only nitrogen and oxygen but also argon as a product while reducing power consumption and downsizing the apparatus by using the nitrogen gas separated in the distillation tower as a heat medium of the heat exchange type distillation apparatus. An object of the present invention is to provide an air liquefaction separation method and apparatus that can be collected and that can further reduce power consumption by circulating and using the nitrogen gas.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the air liquefaction separation method according to the present invention introduces compressed, purified, and cooled raw material air into a distillation column, and performs low-temperature distillation in the distillation column, whereby nitrogen gas at the top of the column and nitrogen at the bottom of the column are separated. And the crude liquefied oxygen led out from the distillation column is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, The temperature of the nitrogen gas derived from the distillation column is raised, and a part of the nitrogen gas is pressurized, and then cooled again, and then introduced as a descending gas into the condensation passage of the heat exchange distillation apparatus, and the fluid in the distillation passage It is condensed by heat exchange to form liquefied nitrogen, and the liquefied nitrogen is decompressed before being used as the reflux liquid of the distillation column. The nitrogen gas and the crude liquefied oxygen are heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the falling liquid are brought into gas-liquid contact in the distillation passage. Nitrogen gas containing oxygen is separated in the upper part of the passage, and liquefied oxygen is separated in the lower part of the distillation passage, and the liquefied oxygen is collected as product oxygen.
[0008]
Furthermore, the air liquefaction separation method of the present invention comprises: The compressed, purified, and cooled raw material air is introduced into the distillation column, and is separated into crude liquefied oxygen containing nitrogen gas at the top of the column and nitrogen at the bottom of the column by low-temperature distillation in the distillation column, and then derived from the distillation column. The crude liquefied oxygen is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and the nitrogen gas derived from the distillation column is introduced into the condensing passage of the heat exchange type distiller as a descending gas. The crude liquefied oxygen is heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the descending liquid are brought into gas-liquid contact in the distillation passage so as to be in the upper part of the distillation passage. Nitrogen gas containing oxygen is separated into liquefied oxygen at the lower part of the distillation passage, and the liquefied oxygen is collected as product oxygen; Derived as liquid coarse liquefied argon from the distillation tower, introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and raised by vaporizing a part of the coarse liquefied argon by heat exchange with nitrogen gas in the condensation passage Gas, and ascending gas and falling liquid are brought into gas-liquid contact in the distillation passage to separate nitrogen gas containing argon in the upper portion of the distillation passage and liquefied argon in the lower portion of the distillation passage, respectively. Is collected as product argon, and nitrogen gas containing argon at the top is reintroduced into the distillation column.
[0009]
Further, in the method of the present invention, instead of the nitrogen gas, a part of the cooled raw air can be introduced as a descending gas into the condensation passage of the heat exchange type distiller. wear .
[0010]
Furthermore, high-pressure product oxygen gas can be obtained by increasing the pressure of the liquefied oxygen derived from the distillation passage and then evaporating it. The cold necessary for operation can be obtained by adiabatically expanding at least one part of the source air and the separation gas, and the source air is secondarily compressed using the expansion work generated by the adiabatic expansion. You can also.
[0011]
In addition, instead of deriving the crude liquefied argon from the distillation column, it is derived as a gaseous crude argon gas, and the derived crude argon gas is introduced into the argon distillation column and further subjected to low-temperature distillation to form nitrogen gas. The liquefied argon can be separated into the liquefied argon, and the separated liquefied argon can be introduced into the distillation passage of the heat exchange type distiller as a descending liquid.
[0012]
The air liquefaction separation apparatus of the present invention includes a raw material air compressor that compresses raw material air, a purifier that removes impurities that solidify at a low temperature, such as moisture and carbon dioxide, contained in the compressed raw material air, A main heat exchanger for cooling the raw material air, a distillation tower for separating the cooled raw air into nitrogen gas and crude liquefied oxygen by low-temperature distillation, and a heat-exchange distiller having a distillation passage and a condensation passage The heat exchange-type distiller is configured to perform gas exchange by heat exchange between a path for introducing the crude liquefied oxygen separated by the distillation column as a descending liquid into the distillation passage and a fluid flowing through the condensation passage in the distillation passage. A route for deriving nitrogen gas containing oxygen that has been converted to an upper portion of the distillation passage and a route for deriving liquefied oxygen lowered to the lower portion of the distillation passage as product oxygen, A path for introducing a part of the nitrogen gas derived from the upper part of the distillation column into the main heat exchanger, and a path for deriving the nitrogen gas heated in the main heat exchanger and introducing it into the circulating nitrogen compressor; A path for introducing compressed nitrogen gas compressed by the circulating nitrogen compressor into the main heat exchanger, and a condensed passage of the heat exchanger type distiller by extracting compressed nitrogen gas cooled by the main heat exchanger In Liquefied nitrogen that has been liquefied by heat exchange between the path to be introduced as the descending gas and oxygen flowing through the distillation path in the condensing passage and descended to the lower part of the condensing passage And then introduced as reflux into the top of the distillation column after decompression It is characterized by having a route to perform.
[0013]
Further, the air liquefaction separation apparatus of the present invention derives crude argon containing nitrogen generated in the middle of the tower when the raw air is subjected to low-temperature distillation in the distillation tower from the distillation tower as liquid crude liquefied argon, and the heat exchange A nitrogen gas containing argon that has been vaporized by heat exchange between a passage for introducing a descending liquid into a part of a distillation passage of the mold distiller and a fluid flowing through the condensation passage in the distillation passage and has risen to the upper portion of the distillation passage. It is characterized in that there are provided a route for leading out and a route for collecting the liquefied argon descending at the lower part of the distillation passage as product argon.
[0014]
Further, as means for introducing the crude liquefied argon into the distillation passage, an argon distillation tower for separating the crude argon gas into nitrogen gas and crude liquefied argon by low-temperature distillation is provided, and the argon distillation tower is provided with a tower of the distillation tower. The crude argon produced in the middle is led out as gaseous crude argon gas, the path for introducing it into the argon distillation column, the path for leading out the nitrogen gas separated in the argon distillation tower, and the separated crude liquefied argon in the distillation It is possible to employ a route for introducing the liquid into the passage as a descending liquid.
[0015]
Furthermore, a gas-liquid separator is provided in the lower part of the distillation passage, and a liquefied oxygen supply pump for supplying the crude liquefied oxygen derived from the distillation column to the distillation passage of the heat exchange type distillation device is provided. It is characterized by having a liquefied oxygen pressurizing pump that pressurizes liquefied oxygen derived from the distillation passage of the heat exchange type still.
[0016]
In addition, instead of nitrogen, the condenser passage is liquefied by heat exchange between a path for introducing a part of the cooled raw material air as a descending gas to the condensation passage and a fluid flowing through the distillation passage in the condensation passage. And a path for leading the liquefied air descending to the lower part of the condensing passage.
[0018]
A path through which a part of the pressurized nitrogen gas is branched from the middle of the main heat exchanger and introduced into the expansion turbine; and the low-temperature nitrogen gas that is adiabatically expanded by the expansion turbine to generate cold is supplied to the main heat exchanger. A path for introducing the raw air from the middle of the main heat exchanger, and a secondary air compressor for low-temperature compression of the raw air led to the path, The secondary air compressor is generated by expansion work generated by adiabatic expansion in the expansion turbine, or by adiabatic expansion in an air expansion turbine that adiabatically expands high-pressure raw material air compressed at low temperature by the secondary air compressor. It is characterized by being driven by using the expanding work.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system diagram showing a first embodiment of the air liquefaction separation apparatus of the present invention, and FIG. 2 is a partial sectional perspective view showing one embodiment of a heat exchange type distiller used in the present invention.
[0020]
This air liquefaction separation apparatus is solidified at a low temperature such as moisture and carbon dioxide contained in the compressed raw material air, a raw air compressor 1 that compresses the raw material air, an air precooler 2 that removes the compression heat of the compressed air, and A purifier 3 for removing impurities, a main heat exchanger 4 for cooling the purified raw material air by heat exchange with a fluid obtained by low-temperature distillation, and a distillation column 5 for low-temperature distillation of the cooled raw material air A heat exchange type distiller 6 having an oxygen distillation passage (oxygen distillation passage) 61, an argon distillation passage (argon distillation passage) 62, and a nitrogen condensation passage (nitrogen condensation passage) 63; and a nitrogen circulation passage. The circulating nitrogen compressor 7 to be formed and the expansion turbine 8 that generates cold are the main constituent devices, and the low-temperature specification devices are housed in the cold storage tank 9.
[0021]
The oxygen distillation passage 61 and the argon distillation passage 62 in the heat exchange-type distiller 6 are in a heat exchange relationship with the nitrogen condensation passage 63, respectively, and the oxygen distillation passage 61 and the argon distillation passage 62 are heated and nitrogen condensed. The passage 63 is the cooled side. In FIG. 1, each passage 61, 62, 63 is shown by a single line for simplification of the drawing, but an actual heat exchange type distiller 6 has a configuration as shown in FIG. 2. It has become.
[0022]
The heat exchange type distiller 6 shown in FIG. 2 uses a plate fin type heat exchanger 10 as the heat exchange type distiller 6, and is condensed with the distillation passage 12 by a large number of partition plates 11 installed in the vertical direction. The passages 13 are alternately stacked, and a distillation passage for leading the gas vaporized in the distillation passage 12 and a distillation passage liquid introduction header 14 for introducing crude liquefied oxygen or coarse liquefied argon into the distillation passage 12 at the upper part of the heat exchanger. The gas outlet header 15 is provided at the lower part of the heat exchanger so that the distillation passage liquid outlet header 16 for leading the liquid (liquefied oxygen, liquefied argon) descending in the distillation passage 12 communicates with the distillation passage 12. In addition, a condensation passage gas introduction header 17 for introducing nitrogen gas into the condensation passage 13 is provided at the upper side of the heat exchanger side, and a condensation passage for deriving liquefied nitrogen liquefied in the condensation passage 13 is provided at the lower portion. The liquid outlet header 18 is provided so as each to communicate with the condensate passage 13. In addition, a liquid distributor 19 is provided at the upper part of the distillation passage 12 to allow the liquid to flow uniformly into each distillation passage 12, and the oxygen side and the argon side are separated by a wall plate 11 a orthogonal to the partition plate 11. It has been. Furthermore, piping which constitutes each route described later is connected to each of these headers.
[0023]
Hereinafter, a procedure for obtaining nitrogen, oxygen and argon by cryogenic liquefaction separation of air will be described with reference to FIG. First, the raw material air is compressed to a predetermined pressure by the raw material air compressor 1 and cooled to room temperature by the air precooler 2, and then impurities such as moisture and carbon dioxide in the raw material air are adsorbed and removed by the purifier 3. The The purified raw material air flows into the cold insulation tank 9 from the path 21 and is cooled to a predetermined temperature by exchanging heat with a low-temperature fluid composed of a product gas and exhaust gas described later in the main heat exchanger 4. Further, the raw air passes through the supercooler 23 from the path 22 and is introduced into the middle lower part of the distillation column 5 via the path 24.
[0024]
The raw material air introduced into the distillation column 5 rises while enriching the nitrogen component, which is a low-boiling component, by gas-liquid contact with the reflux liquid descending in the column, and nitrogen gas is separated at the top of the column. This nitrogen gas is led out to the path 25 from the upper part of the distillation column 5, is introduced into the main heat exchanger 4 through the supercooler 23 and the path 26, and after being heated, is collected as nitrogen gas GN from the path 27.
[0025]
On the other hand, the reflux liquid flowing down the distillation column 5 flows down while enriching the oxygen component which is a high-boiling component by gas-liquid contact with the rising gas rising in the column, and the crude liquefied oxygen containing nitrogen content at the bottom of the column Is separated. The crude liquefied oxygen is led out to the path 31 from the lower part of the distillation column 5, and after the pressure is increased to a predetermined pressure by the liquefied oxygen supply pump 32, the liquefied oxygen descends into the oxygen distillation passage 61 of the heat exchange distiller 6 via the path 33. As introduced.
[0026]
The crude liquefied oxygen flowing down in the oxygen distillation passage 61 is heated by exchanging heat with the fluid flowing through the adjacent nitrogen condensation passage 63, that is, nitrogen gas, and a part of the crude liquefied oxygen is vaporized, and the oxygen distillation passage 61 is heated. Rise inside. At this time, since nitrogen, which is a low-boiling component, in the crude liquefied oxygen is vaporized more, the descending liquid is brought into gas-liquid contact in the process of rising in the oxygen distillation passage 61, and the oxygen distillation passage 61 is enriched while enriching the nitrogen content. It is led out from the path 34. The nitrogen gas containing a small amount of oxygen is returned to the lower part of the distillation column 5 and becomes a rising gas.
[0027]
In addition, the falling liquid that descends without being vaporized in the oxygen distillation passage 61 flows down while enriching oxygen, which is a high-boiling component, and becomes liquefied oxygen in the lower part of the oxygen distillation passage 61. The liquefied oxygen is extracted into the path 35 and introduced into the gas-liquid separator 36. The liquefied oxygen separated from the gas and liquid is vaporized through the main heat exchanger 4 from the path 37 and heated up, and then the path 38. Is collected as oxygen gas GO. At this time, as shown by a broken line in FIG. 1, a liquefied oxygen boost pump 39 is provided in the path 38, and the pressure is increased by the liquefied oxygen boost pump 39 and then vaporized by the main heat exchanger 4. Product oxygen gas can be obtained.
[0028]
Further, the nitrogen gas introduced into the nitrogen condensing passage 63 of the heat exchange type distiller 6 branches a part of the nitrogen gas extracted from the upper part of the distillation column 5 into the path 25 to the path 41 and circulates this nitrogen gas. I am trying to use it. That is, the nitrogen gas branched into the path 41 is heated by the main heat exchanger 4 to normal temperature, led out from the cold storage tank 9 through the path 42, and compressed to a predetermined pressure by the circulating nitrogen compressor 7. . After the compression heat is removed by the nitrogen precooler 43, the compressed nitrogen gas is again introduced into the cold insulation tank 9 through the path 44 and is cooled again to a predetermined temperature by the main heat exchanger 4. The cooled compressed nitrogen gas is introduced as a descending gas into the nitrogen condensing passage 63 of the heat exchange-type distiller 6 through the passage 45 and exchanges heat with the fluid flowing through the adjacent oxygen distillation passage 61 and the argon distillation passage 62. .
[0029]
At this time, the compressed nitrogen gas flowing down the nitrogen condensing passage 63 is set to a high temperature by increasing the pressure, and the crude liquefied oxygen and the rough flowing through the oxygen distillation passage 61 and the argon distillation passage 62 adjacent to the nitrogen condensing passage 63 are set. Since the temperature is higher than that of liquefied argon, it acts as a reboyl gas source for vaporizing the liquefied oxygen and the liquefied argon. Therefore, the compressed nitrogen gas is cooled by applying heat to the crude liquefied oxygen and the crude liquefied argon flowing through the oxygen distillation passage 61 and the argon distillation passage 62 respectively while flowing down the nitrogen condensing passage 63. It condenses and becomes liquefied nitrogen and flows out from the lower part of the nitrogen condensing passage 63 to the path 46. The liquefied nitrogen in the path 46 is led out to the path 47 through the supercooler 23, and after being depressurized to near the operating pressure of the distillation column 5 by the pressure reducing valve 48, is returned as a reflux liquid from the path 49 to the upper portion of the distillation column 5. .
[0030]
Further, a part of the compressed nitrogen gas introduced into the main heat exchanger 4 from the path 44 is branched into the path 51 from the middle of the main heat exchanger 4 and introduced into the expansion turbine 8, and is insulated by the expansion turbine 8. The expansion generates the cold necessary for the operation of the device. The low-temperature nitrogen gas having obtained the cold is led out from the expansion turbine 8 to the path 52, merges with the nitrogen gas in the path 26, flows into the main heat exchanger 4, and is led out from the path 27 after being heated.
[0031]
Furthermore, in the present embodiment, in order to collect argon, crude liquefied argon composed of substantially nitrogen and argon is led out from the middle upper part of the distillation column 5 to the path 71, and is fed to the argon distillation passage 62 of the heat exchange type distiller 6. It is introduced as a descending liquid. The crude liquefied argon, like the crude liquefied oxygen, exchanges heat with the nitrogen gas flowing through the adjacent nitrogen condensation passage 63, and partly vaporizes and rises while enriching the nitrogen content in the argon distillation passage 62. The nitrogen gas containing a small amount of argon is led out to the path 72 and returned to the upper part of the distillation column 5 to become the rising gas.
[0032]
Further, the falling liquid in the argon distillation passage 62 flows down while enriching argon, which is a high-boiling component, and becomes liquefied argon, which is extracted from the lower portion of the argon distillation passage 62 to the passage 73, and the gas-liquid separator 74 is connected to the argon distillation passage 62. Then, it is collected from the path 75 as product liquefied argon LAr.
[0033]
FIG. 3 is a system diagram showing a second embodiment of the air liquefaction separation apparatus of the present invention. In the following description, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof is omitted.
[0034]
In the present embodiment, a crude argon gas composed of substantially nitrogen and argon is led out from the middle upper part of the distillation column 5 to the path 81 and introduced into the argon distillation tower 82 to be separated into nitrogen gas and crude liquefied argon. The crude liquefied argon separated into (3) is introduced as a descending liquid into the argon distillation passage 62 of the heat-exchange distiller 6 from the path 83, and nitrogen gas containing a small amount of argon that has risen through the argon distillation path 62 is argon distilled from the path 84 The rising gas is returned to the lower part of the tower 82. Further, liquefied nitrogen branched from the path 49 to the path 85 is introduced as a reflux liquid in the upper part of the argon distillation column 82, and the nitrogen gas separated in the upper part of the tower is led out to the path 86 and joined to the path 25. .
[0035]
That is, in the argon distillation column 82, low-temperature distillation is performed with the crude argon gas introduced as the rising gas at the lower part of the tower and the liquefied nitrogen introduced as the reflux liquid at the upper part of the tower. As a result of the contact, the rising gas rises in the tower while enriching nitrogen, which is a low-boiling component, and the reflux liquid descends in the tower, while enriching argon, which is a high-boiling component. As a result, nitrogen gas is separated at the upper part of the tower and crude liquefied argon is separated at the lower part of the tower.
[0036]
The crude liquefied argon introduced as a descending liquid from the argon distillation column 82 to the argon distillation passage 62 is heated by nitrogen gas flowing through the nitrogen condensation passage 63 in the same manner as described above. A certain amount of nitrogen is vaporized, and the vaporized gas rises in the argon distillation passage 62 while being enriched with nitrogen, and is returned to the argon distillation column 82. On the other hand, the liquid that descends the argon distillation passage 62 without being vaporized reaches the lower portion of the argon distillation passage 62 while enriching argon, which is a high boiling point component, and passes through the path 73, the gas-liquid separator 74, and the path 75 to liquefy the product liquefied argon. Collected as LAr.
[0037]
FIG. 4 is a system diagram showing a third embodiment of the air liquefaction separation apparatus of the present invention. In the present embodiment, the raw material air purified by the purifier 3 and introduced into the main heat exchanger 4 from the path 21 is led to the path 91 from the middle of the main heat exchanger 4 and then the two secondary airs. The air is introduced into the air compressor 92 and compressed at a low temperature to a predetermined pressure. The low-pressure compressed high-pressure raw material air is again introduced into the main heat exchanger 4 through the path 93 and cooled, and then branched into a path 94 and a path 95. The high-pressure raw material air in the path 94 is freely expanded by the pressure reducing valve 96 to become low-temperature air, and then is introduced from the path 97 through the supercooler 23 and into the distillation column 5 through the path 24. Further, the high-pressure raw material air branched into the path 95 is introduced into the air expansion turbine 98 and adiabatically expanded to become low-temperature air. After being led out to the path 99, it joins with the low-temperature air in the path 97 and enters the distillation column 5. be introduced.
[0038]
Further, a part of the compressed nitrogen gas compressed by the circulating nitrogen compressor 7 branches from the path 44 to the path 53 and is introduced into the expansion turbine 8 and adiabatically expands to become low-temperature nitrogen gas, which is led to the path 54. The This low-temperature nitrogen gas merges with the nitrogen gas introduced into the main heat exchanger 4 from the path 26 in the middle of the main heat exchanger 4, and the cold is recovered and led out from the path 27.
[0039]
The secondary air compressor 92 is driven by using expansion work generated by adiabatic expansion in the expansion turbine 8 and the air expansion turbine 98, so that cold can be generated effectively and power consumption is increased. The amount can be reduced.
[0040]
Here, in the oxygen distillation passage 61 of the heat exchange-type distiller 6, a part of the crude liquefied oxygen supplied to the oxygen distillation passage 61 is gasified by receiving heat supply from the nitrogen gas flowing through the nitrogen condensation passage 63. To generate rising gas. The flow rate of the nitrogen gas flowing through the nitrogen condensing passage 63 is determined by making the amount of heat of vaporization of the crude liquefied oxygen and the amount of heat of liquefaction of the nitrogen gas flowing through the nitrogen condensing passage 63 commensurate with the amount of the rising gas generated here. .
[0041]
At this time, the flow rate of nitrogen gas in the nitrogen condensing passage 63 can be arbitrarily set by circulating the nitrogen gas as described above, so that the amount of coarsely liquefied oxygen can also be arbitrarily set. Since this crude liquefied oxygen is supplied as a descending liquid to the upper part of the heat exchange type distiller 6, it corresponds to a reflux liquid in the oxygen distillation passage 61. Therefore, the amount of reflux liquid can be set arbitrarily, the reflux ratio can be increased, and the internal reflux ratio of the oxygen distillation passage 61 can be increased. Further, in the conventional air liquefaction separation apparatus, the argon-oxygen mixed gas is side-cut from the low-pressure column in order to recover argon, whereas in the present invention, the nitrogen / argon-based mixed gas having a large relative volatility is used. Since the mixed fluid can be side-cut from the distillation column 5, distillation in the argon distillation passage 62 and the argon distillation column 82 can be dramatically accelerated. Thereby, nitrogen gas, liquefied argon, and oxygen gas can be efficiently recovered as a product with the apparatus configuration reduced in size by reducing the height of the apparatus.
[0042]
In each embodiment, the crude liquefied oxygen derived from the lower part of the distillation column 5 is supplied to the oxygen distillation passage 61 by the liquefied oxygen supply pump 32. However, the positional relationship between the distillation column 5 and the heat exchange type distiller 6 is used. Depending on the case, the liquefied oxygen supply pump 32 can be omitted. Moreover, the introduction position of the raw material air to the distillation column 5 is arbitrary, and may be introduced to the lower portion of the column. Furthermore, it is possible to introduce a part of the raw air instead of nitrogen gas into the condensing passage 63 of the heat exchange type distiller 6 as a reboil gas source, and the liquefied air is placed at an appropriate position in the distillation column 5. It can be introduced as a descending liquid.
[0043]
【Example】
An operation of collecting nitrogen, oxygen, and argon was performed using the first embodiment apparatus having the configuration shown in FIG. First, after the raw material air compressed to 170 kPa by the raw material air compressor 1 is cooled to room temperature by the air precooler 2, the impurities are adsorbed and removed by the purifier 3, and then the gas-liquid at about −190 ° C. by the main heat exchanger 4. After cooling to a two-phase state, it was introduced into the distillation column 5. As a result of the low temperature distillation in the distillation column 5, nitrogen gas having a nitrogen concentration of 99.99% or more and an oxygen content of 1 ppb or less was obtained from the top of the column.
[0044]
The crude liquefied oxygen in the lower part of the tower is introduced as a descending liquid (reflux) into the upper part of the oxygen distillation passage 61 of the heat exchange-type distiller 6, and is subjected to heat exchange with the circulating nitrogen gas flowing through the nitrogen condensing passage 63. Went. As a result, liquefied oxygen having an oxygen purity of 99.5% or more could be obtained from the lower part of the oxygen distillation passage 61. At this time, circulating nitrogen gas compressed to 490 kPa by the circulating nitrogen compressor 7 and cooled to −179.6 ° C. by the main heat exchanger 4 was introduced into the nitrogen condensing passage 63 as a descending gas.
[0045]
Further, from the upper part of the distillation column 5, the liquefied argon having an argon content of 20% or more and the balance being substantially nitrogen is side-cut and introduced as a descending liquid into the argon distillation passage 62 of the heat exchange type distillation apparatus 6, Heat exchange was performed with nitrogen gas in the nitrogen condensing passage 63. As a result, liquefied argon having a purity of 98% or more was recovered from the lower part of the argon distillation passage 62.
[0046]
Further, when the second embodiment apparatus shown in FIG. 3 is used, the crude argon gas of substantially nitrogen and argon (content of 10% or more) is side-cut from the upper part of the distillation column 5, and the argon distillation column 82 Distillation was performed at the bottom. From the upper part of the argon distillation column 82, nitrogen gas having a nitrogen concentration of 99.99% or more and an oxygen content of 1 ppb or less was obtained. Moreover, as a result of introducing the crude liquefied argon at the bottom of the tower as a descending liquid into the argon distillation passage 62 of the heat exchange type distillation apparatus 6, liquefied argon having a purity of 98% or more was obtained from the lower portion of the argon distillation passage 62.
[0047]
【The invention's effect】
As described above, according to the present invention, in the air deep liquefaction separation method and apparatus using a heat exchange type distiller, nitrogen, argon and oxygen can be collected simultaneously as products. In addition, in the present invention, the height of the cold storage tank is compared with the height of the cold storage tank in an air separation apparatus using a conventional regular packed distillation column for collecting products of the same quality (purity, quantity, pressure). It can be reduced to about 65%, and the apparatus cost can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a first embodiment of an air liquefaction separation apparatus according to the present invention.
FIG. 2 is a partial cross-sectional perspective view showing one embodiment of a heat exchange type distiller used in the present invention.
FIG. 3 is a system diagram showing a second embodiment of the air liquefaction separation apparatus of the present invention.
FIG. 4 is a system diagram showing a third embodiment of the air liquefaction separation apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Raw material air compressor, 2 ... Air precooler, 3 ... Purifier, 4 ... Main heat exchanger, 5 ... Distillation tower, 6 ... Heat exchange type distiller, 7 ... Circulating nitrogen compressor, 8 ... Expansion turbine, DESCRIPTION OF SYMBOLS 9 ... Cold storage tank, 14 ... Distillation passage liquid introduction header, 15 ... Distillation passage gas extraction header, 16 ... Distillation passage liquid introduction header, 17 ... Condensation passage gas introduction header, 18 ... Condensation passage liquid extraction header, 23 ... Supercooler 32 ... liquefied oxygen supply pump, 36 ... gas-liquid separator, 39 ... liquefied oxygen boost pump, 61 ... oxygen distillation passage, 62 ... argon distillation passage, 63 ... nitrogen condensation passage, 82 ... argon distillation tower, 92 ... secondary Air compressor 96 ... Pressure reducing valve 98 ... Air expansion turbine

Claims (16)

圧縮、精製、冷却した原料空気を蒸留塔に導入し、該蒸留塔で低温蒸留することによって塔上部の窒素ガスと塔下部の窒素を含む粗液化酸素とに分離した後、蒸留塔から導出した前記粗液化酸素を熱交換型蒸留器の蒸留通路に下降液として導入するとともに、前記蒸留塔から導出した窒素ガスを昇温し、その一部を昇圧した後、再度冷却してから前記熱交換型蒸留器の凝縮通路に下降ガスとして導入し、前記蒸留通路内の流体との熱交換により凝縮させて液化窒素とし、該液化窒素を減圧してから前記蒸留塔の還流液とし、該窒素ガスと前記粗液化酸素とを熱交換させることにより前記液化酸素の一部を気化させて上昇ガスとし、該蒸留通路内で上昇ガスと下降液とを気液接触させることによって該蒸留通路の上部に酸素を含む窒素ガスを、該蒸留通路の下部に液化酸素をそれぞれ分離し、該液化酸素を製品酸素として採取することを特徴とする空気液化分離方法。The compressed, purified, and cooled raw material air is introduced into the distillation column, and is separated into crude liquefied oxygen containing nitrogen gas at the top of the column and nitrogen at the bottom of the column by low-temperature distillation in the distillation column, and then derived from the distillation column. The crude liquefied oxygen is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and the nitrogen gas derived from the distillation tower is heated, and after a part of the pressure is increased, the heat is cooled again and the heat exchange is performed. The gas is introduced as a descending gas into the condensing passage of the type distiller, condensed by heat exchange with the fluid in the distillation passage to form liquefied nitrogen, the liquefied nitrogen is decompressed and then used as the reflux liquid of the distillation column, and the nitrogen gas The crude liquefied oxygen is heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the descending liquid are brought into gas-liquid contact in the distillation passage so as to be in the upper part of the distillation passage. Nitrogen gas containing oxygen, Cryogenic air separation method characterized by the bottom of the distillation path liquid oxygen are separated respectively, collecting the liquefied oxygen as product oxygen. 前記蒸留通路から導出した液化酸素を昇圧してから気化させることにより、高圧の製品酸素ガスを得ることを特徴とする請求項１記載の空気液化分離方法。 2. The air liquefaction separation method according to claim 1, wherein high-pressure product oxygen gas is obtained by increasing the pressure of the liquefied oxygen derived from the distillation passage and then evaporating it. 運転に必要な寒冷を、原料空気、分離ガスの少なくともいずれか一部を断熱膨張させることによって得ることを特徴とする請求項１記載の空気液化分離方法。 2. The air liquefaction separation method according to claim 1, wherein the cooling required for operation is obtained by adiabatic expansion of at least one of raw material air and separation gas. 前記断熱膨張で発生する膨張仕事を利用して前記原料空気を二次圧縮することを特徴とする請求項３記載の空気液化分離方法。The air liquefaction separation method according to claim 3, wherein the raw material air is secondarily compressed using expansion work generated by the adiabatic expansion. 前記熱交換型蒸留器の凝縮通路に、前記窒素ガスに代えて冷却後の原料空気の一部を下降ガスとして導入することを特徴とする請求項１乃至４記載の空気液化分離方法。It claims 1 to 4 the method of cryogenic air separation wherein introducing the condensing passage of the heat exchanging type distillation apparatus, a portion of the feed air after cooling the descending gas instead of the nitrogen gas. 圧縮、精製、冷却した原料空気を蒸留塔に導入し、該蒸留塔で低温蒸留することによって塔上部の窒素ガスと塔下部の窒素を含む粗液化酸素とに分離した後、蒸留塔から導出した前記粗液化酸素を熱交換型蒸留器の蒸留通路に下降液として導入するとともに、前記蒸留塔から導出した前記窒素ガスを前記熱交換型蒸留器の凝縮通路に下降ガスとして導入し、該窒素ガスと前記粗液化酸素とを熱交換させることにより前記液化酸素の一部を気化させて上昇ガスとし、該蒸留通路内で上昇ガスと下降液とを気液接触させることによって該蒸留通路の上部に酸素を含む窒素ガスを、該蒸留通路の下部に液化酸素をそれぞれ分離し、該液化酸素を製品酸素として採取し、前記蒸留塔での低温蒸留によって原料空気を窒素ガスと粗液化酸素とに分離する際に塔中部に生成する窒素を含む粗アルゴンを該蒸留塔から液状の粗液化アルゴンとして導出し、前記熱交換型蒸留器の蒸留通路に下降液として導入し、前記凝縮通路の窒素ガスとの熱交換により粗液化アルゴンの一部を気化させて上昇ガスとし、該蒸留通路内で上昇ガスと下降液とを気液接触させることによって該蒸留通路の上部にアルゴンを含む窒素ガスを、該蒸留通路の下部に液化アルゴンをそれぞれ分離し、該液化アルゴンを製品アルゴンとして採取するとともに、上部のアルゴンを含む窒素ガスを前記蒸留塔に再導入することを特徴とする空気液化分離方法。 The compressed, purified, and cooled raw material air is introduced into the distillation column, and is separated into crude liquefied oxygen containing nitrogen gas at the top of the column and nitrogen at the bottom of the column by low-temperature distillation in the distillation column, and then derived from the distillation column. The crude liquefied oxygen is introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and the nitrogen gas derived from the distillation column is introduced into the condensing passage of the heat exchange type distiller as a descending gas. The crude liquefied oxygen is heat-exchanged to vaporize a part of the liquefied oxygen to form a rising gas, and the rising gas and the descending liquid are brought into gas-liquid contact in the distillation passage so as to be in the upper part of the distillation passage. Nitrogen gas containing oxygen is separated into liquefied oxygen at the lower part of the distillation passage, the liquefied oxygen is collected as product oxygen, and the raw air is separated into nitrogen gas and crude liquefied oxygen by low-temperature distillation in the distillation tower. Do The crude argon containing nitrogen generated in the middle of the column is led out from the distillation column as liquid crude liquefied argon, introduced as a descending liquid into the distillation passage of the heat exchange type distiller, and heated with the nitrogen gas in the condensation passage A part of the crude liquefied argon is vaporized by exchange to form an ascending gas, and the ascending gas and the descending liquid are brought into gas-liquid contact in the distillation passage to thereby convert nitrogen gas containing argon into the upper portion of the distillation passage. A liquid liquefaction separation method characterized by separating liquefied argon in the lower part of each, collecting the liquefied argon as product argon, and reintroducing nitrogen gas containing argon in the upper part into the distillation column. 前記蒸留塔から粗液化アルゴンを導出するのに代えてガス状の粗アルゴンガスとして導出し、該導出した粗アルゴンガスをアルゴン蒸留塔に導入して更に低温蒸留することにより窒素ガスと粗液化アルゴンとに分離し、分離した粗液化アルゴンを前記熱交換型蒸留器の蒸留通路に下降液として導入することを特徴とする請求項６記載の空気液化分離方法。Instead of deriving crude liquefied argon from the distillation column, it is derived as gaseous crude argon gas, and the derived crude argon gas is introduced into the argon distillation column and further subjected to low-temperature distillation to thereby generate nitrogen gas and crude liquefied argon. 7. The air liquefaction separation method according to claim 6 , wherein the crude liquefied argon is introduced into the distillation passage of the heat exchange distiller as a descending liquid. 原料空気を圧縮する原料空気圧縮機と、圧縮された原料空気中に含まれる水分や二酸化炭素等の低温で固化する不純物を除去する精製器と、精製された原料空気を冷却する主熱交換器と、冷却された原料空気を低温蒸留して窒素ガスと粗液化酸素とに分離する蒸留塔と、蒸留通路及び凝縮通路を有する熱交換型蒸留器とを備え、該熱交換型蒸留器は、前記蒸留塔で分離した前記粗液化酸素を前記蒸留通路に下降液として導入する経路と、該蒸留通路で前記凝縮通路を流れる流体との熱交換により気化して該蒸留通路の上部に上昇した酸素を含む窒素ガスを導出する経路と、該蒸留通路の下部に下降した液化酸素を製品酸素として導出する経路と、前記蒸留塔の上部から導出した窒素ガスの一部を前記主熱交換器に導入する経路と、該主熱交換器で加温された窒素ガスを導出して循環窒素圧縮機に導入する経路と、該循環窒素圧縮機で圧縮した圧縮窒素ガスを前記主熱交換器に導入する経路と、該主熱交換器で冷却された圧縮窒素ガスを導出して前記熱交換器型蒸留器の凝縮通路に下降ガスとして導入する経路と、該凝縮通路で前記蒸留通路を流れる酸素との熱交換により液化して該凝縮通路の下部に下降した液化窒素を導出して減圧後に前記蒸留塔の上部に還流液として導入する経路とを備えていることを特徴とする空気液化分離装置。A raw material air compressor that compresses raw material air, a purifier that removes impurities such as moisture and carbon dioxide contained in the compressed raw material air, and a main heat exchanger that cools the purified raw material air And a distillation column for separating the cooled raw material air at a low temperature into nitrogen gas and crude liquefied oxygen, and a heat exchange distiller having a distillation passage and a condensation passage, Oxygen that is vaporized by heat exchange between a path for introducing the crude liquefied oxygen separated in the distillation column as a descending liquid into the distillation passage and a fluid flowing in the condensation passage in the distillation passage and rises above the distillation passage. A path for deriving nitrogen gas containing oxygen, a path for deriving liquefied oxygen descending to the lower part of the distillation passage as product oxygen , and introducing part of the nitrogen gas derived from the upper part of the distillation column into the main heat exchanger And the main heat exchange A path for deriving the nitrogen gas heated in step and introducing it into the circulating nitrogen compressor, a path for introducing the compressed nitrogen gas compressed by the circulating nitrogen compressor into the main heat exchanger, and the main heat exchanger A path through which cooled compressed nitrogen gas is led out and introduced as a descending gas into the condensation passage of the heat exchanger-type distiller , and the condensation passage is liquefied by heat exchange with oxygen flowing through the distillation passage in the condensation passage. A liquefied nitrogen that descends to the lower part of the liquefied nitrogen, and a passage for introducing the liquefied nitrogen as a reflux into the upper part of the distillation column after decompression . 前記蒸留塔で原料空気を低温蒸留する際に塔中部に生成する窒素を含む粗アルゴンを該蒸留塔から液状の粗液化アルゴンとして導出し、前記熱交換型蒸留器の蒸留通路の一部に下降液として導入する経路と、該蒸留通路で前記凝縮通路を流れる流体との熱交換により気化して該蒸留通路の上部に上昇したアルゴンを含む窒素ガスを導出する経路と、該蒸留通路の下部に下降した液化アルゴンを製品アルゴンとして採取する経路とを設けたことを特徴とする請求項８記載の空気液化分離装置。When the raw air is distilled at a low temperature in the distillation column, crude argon containing nitrogen generated in the middle of the column is led out from the distillation column as liquid crude liquefied argon, and descends to a part of the distillation passage of the heat exchange type distiller. A path for introducing as a liquid, a path for deriving nitrogen gas containing argon which has been vaporized by heat exchange with the fluid flowing through the condensation path in the distillation path and has risen to the upper part of the distillation path, and a lower part of the distillation path The air liquefaction separation apparatus according to claim 8, further comprising a path for collecting the lowered liquefied argon as product argon. 前記蒸留塔から導出した粗液化アルゴンを前記蒸留通路に下降液として導入する経路に代えて、粗アルゴンガスを低温蒸留して窒素ガスと粗液化アルゴンとに分離するアルゴン蒸留塔を設け、該アルゴン蒸留塔に、前記蒸留塔の塔中部に生成した粗アルゴンをガス状の粗アルゴンガスとして導出し、該アルゴン蒸留塔に導入する経路と、該アルゴン蒸留塔で分離した窒素ガスを導出する経路と、分離した粗液化アルゴンを前記蒸留通路に下降液として導入する経路とを設けたことを特徴とする請求項８記載の空気液化分離装置。Instead of the path for introducing the crude liquefied argon derived from the distillation column into the distillation passage as a descending liquid, an argon distillation tower for separating the crude argon gas into nitrogen gas and crude liquefied argon by low-temperature distillation is provided. A path for deriving crude argon generated in the middle of the distillation column as a gaseous crude argon gas into the distillation column and introducing it into the argon distillation tower; and a path for deriving nitrogen gas separated by the argon distillation tower; 9. An air liquefaction separation apparatus according to claim 8 , further comprising a path for introducing the separated crude liquefied argon into the distillation passage as a descending liquid. 前記蒸留通路の下部に気液分離器を設けたことを特徴とする請求項８記載の空気液化分離装置。9. The air liquefaction separation apparatus according to claim 8, wherein a gas-liquid separator is provided in a lower part of the distillation passage. 前記蒸留塔から導出した粗液化酸素を前記熱交換型蒸留器の蒸留通路に供給する液化酸素供給ポンプを備えていることを特徴とする請求項８記載の空気液化分離装置。The air liquefaction separation apparatus according to claim 8 , further comprising a liquefied oxygen supply pump for supplying crude liquefied oxygen derived from the distillation column to a distillation passage of the heat exchange type distiller. 前記熱交換型蒸留器の蒸留通路から導出した液化酸素を昇圧する液化酸素昇圧ポンプを備えていることを特徴とする請求項８記載の空気液化分離装置。9. The air liquefaction separation apparatus according to claim 8, further comprising a liquefied oxygen pressurizing pump that pressurizes liquefied oxygen derived from a distillation passage of the heat exchange type distiller. 前記凝縮通路に、前記窒素の各経路に代えて、冷却後の原料空気の一部を前記凝縮通路に下降ガスとして導入する経路と、該凝縮通路で前記蒸留通路を流れる流体との熱交換により液化して該凝縮通路の下部に下降した液化空気を導出する経路とを設けたことを特徴とする請求項８記載の空気液化分離装置。In place of each of the nitrogen paths in the condensing passage, heat exchange between a path for introducing a part of the cooled raw material air into the condensing path as a descending gas and a fluid flowing through the distillation passage in the condensing path. 9. An air liquefaction separation apparatus according to claim 8, further comprising a path for deriving the liquefied air that has been liquefied and descended below the condensing passage. 前記主熱交換器の途中から前記昇圧窒素ガスの一部を分岐して膨張タービンに導入する経路と、該膨張タービンで断熱膨張して寒冷を発生した低温窒素ガスを前記主熱交換器に導入する経路とを備えていることを特徴とする請求項８記載の空気液化分離装置。A path through which a part of the pressurized nitrogen gas is branched from the middle of the main heat exchanger and introduced into the expansion turbine, and a low-temperature nitrogen gas that is adiabatically expanded by the expansion turbine to generate cold is introduced into the main heat exchanger. The air liquefaction separation apparatus according to claim 8, further comprising: 前記主熱交換器の途中から原料空気を導出する経路と、該経路に導出した原料空気を低温圧縮する二次空気圧縮機を設けるとともに、該二次空気圧縮機を、前記膨張タービンでの断熱膨張で発生する膨張仕事、あるいは、該二次空気圧縮機で低温圧縮された高圧原料空気を断熱膨張させる空気膨張タービンでの断熱膨張で発生する膨張仕事を利用して駆動することを特徴とする請求項１５記載の空気液化分離装置。A path for deriving raw material air from the middle of the main heat exchanger and a secondary air compressor for low-temperature compressing the raw material air led to the path are provided, and the secondary air compressor is insulated by the expansion turbine. It is driven by using expansion work generated by expansion or expansion work generated by adiabatic expansion in an air expansion turbine that adiabatically expands high-pressure raw material air compressed at low temperature by the secondary air compressor. cryogenic air separation unit according to claim 1 5, wherein.
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