JP3884240B2 - Air separation device and control operation method thereof - Google Patents

Air separation device and control operation method thereof Download PDF

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JP3884240B2
JP3884240B2 JP2001145547A JP2001145547A JP3884240B2 JP 3884240 B2 JP3884240 B2 JP 3884240B2 JP 2001145547 A JP2001145547 A JP 2001145547A JP 2001145547 A JP2001145547 A JP 2001145547A JP 3884240 B2 JP3884240 B2 JP 3884240B2
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oxygen
liquid
amount
air
pressure column
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JP2002340478A (en
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正幸 田中
隆司 大山
保 橋本
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Kobe Steel Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04793—Rectification, e.g. columns; Reboiler-condenser
    • 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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/04218—Parallel arrangement of the main heat exchange line in cores having different functions, e.g. in low pressure and high pressure cores
    • 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
    • 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
    • F25J3/04303—Lachmann expansion, i.e. expanded into oxygen producing or 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
    • 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
    • F25J3/04472—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages
    • F25J3/04496—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages for compensating variable air feed or variable product demand by alternating between periods of liquid storage and liquid assist
    • F25J3/04503—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages for compensating variable air feed or variable product demand by alternating between periods of liquid storage and liquid assist by exchanging "cold" between at least two different cryogenic liquids, e.g. independently from the main heat exchange line of the air fractionation and/or by using external alternating storage systems
    • F25J3/04509—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 the cold from cryogenic liquids produced within the air fractionation unit and stored in internal or intermediate storages for compensating variable air feed or variable product demand by alternating between periods of liquid storage and liquid assist by exchanging "cold" between at least two different cryogenic liquids, e.g. independently from the main heat exchange line of the air fractionation and/or by using external alternating storage systems within the cold part of the air fractionation, i.e. exchanging "cold" within the fractionation and/or main heat exchange line
    • F25J3/04515—Simultaneously changing air feed and products output
    • 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
    • F25J3/04521—Coupling of the air fractionation unit to an air gas-consuming unit, so-called integrated processes
    • F25J3/04527—Integration with an oxygen consuming unit, e.g. glass facility, waste incineration or oxygen based processes in general
    • F25J3/04539—Integration with an oxygen consuming unit, e.g. glass facility, waste incineration or oxygen based processes in general for the H2/CO synthesis by partial oxidation or oxygen consuming reforming processes of fuels
    • F25J3/04545—Integration with an oxygen consuming unit, e.g. glass facility, waste incineration or oxygen based processes in general for the H2/CO synthesis by partial oxidation or oxygen consuming reforming processes of fuels for the gasification of solid or heavy liquid fuels, e.g. integrated gasification combined cycle [IGCC]
    • 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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/62—Details of storing a fluid in a tank

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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)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、原料空気から酸素や窒素を分離するための空気分離装置とその制御運転方法に関し、より詳細には、酸素や窒素の需要量の変動に応じて、その変動量を吸収し、当該装置の運転状態を安定に制御し得る様に改善された空気分離装置とその制御運転方法に関するものである。
【０００２】
【従来の技術】
発電設備や製鉄所の如く大量の酸素が消費される工場には、場内に酸素自給のための酸素製造設備を併設することが多く、該酸素製造設備として最も汎用されているのは、空気を原料として酸素を得ることができ、しかも副産物として大量の窒素を得ることのできる空気分離装置である。この空気分離装置は、その規模や付帯設備の性能などによって酸素生産能力は異なるが、該設備の生産能力が最も高められるのは、当該設備に固有の一定（最適）の条件で定常運転したときであり、そのときに最大の生産効率が得られる。
【０００３】
一方、発電設備を考えた場合、電力需要は昼間と夜間とでは大きく変動するため、ガス化発電（IGCC：Integrated Gasification Combined Cycle)に使用される酸素ガス量も昼間と夜間で大きく変動する。そこで通常は、酸素ガス使用量の変動を吸収できるよう貯蔵設備を設けておき、空気分離装置は極力一定の条件で定常運転させる方法が採用されている。
【０００４】
例えば、空気分離装置から送出される製品酸素や製品窒素を圧縮機で圧縮してガスホルダーに一時貯留しておき、製品酸素や製品窒素の需要量に応じてガスホルダーから必要量を送出する方法である。この方法によれば、製品酸素や製品窒素の需要量の変動にかかわらず、空気分離装置を一定の条件で定常運転することができ、当該設備に固有の生産能を最大限に活かすことができる。
【０００５】
しかし、上記ガス化発電プラントの燃料として酸素を供給する場合、製鉄所の例えば転炉に酸素を供給する場合に比べると酸素需要量の変動周期が長いため、一時貯留するガスホルダーの容積を大きくしなければならず、建設費や設備面積の増大による経済的負担が軽視できなくなる。
【０００６】
そこでこの様な問題を解決するため、酸素や窒素を液体で貯留し、需要に応じて該液体酸素や液体窒素を加熱気化させて送出する方法も提案されている。しかしこの様な方法では、酸素需要量の変動には比較的容易に対応できるものの、空気分離設備を構成する精留塔の運転条件や、膨張タービンや主熱交換器でのガス流量が変動する、といった様々な問題が生じ、結果的に当該空気分離装置の効率を低下させる大きな原因になる。
【０００７】
よって、ガスホルダーの如き付帯設備の大型化を伴うことなく、需要量の変動周期が長い設備に酸素ガスを供給するには、製品酸素ガスの需要量に応じて最適量の酸素ガス送出量を確保できる様に空気分離装置を制御運転するのが理想的である。
【０００８】
しかしこれまでの制御運転方法では、空気分離装置を一定の条件で定常運転することを前提としているため、定常運転時における酸素濃度の維持制御はできるものの、製品酸素の要求量の変化に対応して運転条件を自動的に変化させることまでは考えられておらず、運転条件を変える時には、先ず作業員が手動操作によって運転条件を変更し、運転状態が安定したところで自動制御に切り替える方法が採用されている。
【０００９】
このため、製品酸素の要求量に応じて運転条件を変化させるには、作業員に過度の負担を強いることになり、実操業にそぐわない。また空気分離装置では、運転条件を変えた時でも、その変化に対する応答が現われるのが非常に遅いため、これまで提案されている様に、状態変化が生じてから調節器を調節するフィードバック制御では十分に対応できない。
【００１０】
【発明が解決しようとする課題】
本発明は上記の様な事情に鑑みてなされたものであり、その目的は、ガスホルダーなどの付帯設備を大型化することなく、需要量の変動周期が長い設備に適用する場合でも、酸素濃度や窒素濃度を低下させることなく、需要量に応じて製品酸素や製品窒素を安定して供給することのできる空気分離装置とその制御運転方法を提供することにある。
【００１１】
【課題を解決するための手段】
上記課題を解決することのできた本発明に係る空気分離装置とは、原料空気を液体酸素と気体窒素に分離する高圧塔と低圧塔と、分離された液体酸素を貯溜する液体酸素貯槽、および、圧縮された原料空気を熱源とし液体酸素を気化させて製品酸素ガスとする酸素蒸発器を備えた空気分離装置において、
製品酸素ガス送出要求量の変動を指示する制御部と、該制御部からの指示により前記酸素蒸発器から送り出される製品酸素流量を制御する酸素流量制御器と、原料空気の供給路から分岐され前記酸素蒸発器における熱交換によって液化された液体空気を貯溜するとともに、その貯溜したその液体空気を、分岐された他方の原料空気に合流させて前記高圧塔に供給するための液体空気貯槽とを有し、
さらに、前記制御部から指示される製品酸素流量に対応して、
酸素蒸発器へ供給される必要な圧縮空気量を演算し、前記酸素蒸発器に導入する圧縮空気量を制御する圧縮空気量演算・制御部と、高圧塔から低圧塔へ送られる必要な窒素リッチ液量を演算し制御する窒素リッチ液量演算・制御部と、高圧塔から低圧塔へ送られる必要な酸素リッチ液量を演算し制御する酸素リッチ液量演算・制御部と、低圧塔底部から液体酸素貯槽へ送られる必要な液体酸素量を演算し制御する液体酸素量演算・制御部と、を備えているところに要旨を有している。
【００１２】
本発明の上記空気分離槽値においては、他の構成要素として、前記低圧塔の塔底部に液体酸素濃度測定器を設けると共に、該低圧塔と液体酸素貯槽を結ぶラインに液体酸素抜出量調節弁を設け、低圧塔底部の液体酸素濃度に応じて液体酸素抜出量を調節可能にし、あるいは更に、前記低圧塔の塔頂部に酸素濃度測定器を設けると共に、該高圧塔と低圧塔を結ぶ窒素リッチ液管路に流量調節弁を設け、低圧塔頂部の酸素濃度に応じて、高圧塔から低圧塔への窒素リッチ液量を調節できる様にしたものは、製品酸素濃度を一層安定に維持可能にしたものとして推奨される。
【００１３】
また本発明にかかる制御運転方法とは、原料空気を液体酸素と気体窒素に分離する高圧塔および低圧塔と、分離された液体酸素を貯溜する液体酸素貯槽と、圧縮された原料空気を熱源とし液体酸素を気化させて製品酸素ガスとする酸素蒸発器と、原料空気の供給路から分岐され前記酸素蒸発器における熱交換によって液化された液体空気を貯留するとともに、貯留したその液体空気を、分岐された他方の原料空気に合流させて前記高圧塔に供給するための液体空気貯槽とを備えた空気分離装置を操業するに当たり、
該製品酸素ガスの送出要求量に対応して、前記酸素蒸発器へ送られる必要な原料空気量と、前記高圧塔から低圧塔へ送られる必要な窒素リッチ液および酸素リッチ液の量、および、低圧塔底部から液体酸素貯槽へ送られる必要な液体酸素の量を、前記製品酸素ガスの濃度が所定値となる様に夫々演算し、該演算値に基づいて制御運転を行ない、
製品酸素ガスの送出要求量が増加した場合に、前記液体酸素貯槽に貯溜されている液体酸素量を減らす一方で、液体酸素の気化に供せられて増加した液体空気を前記液体空気貯 槽に貯蔵し、また、製品酸素ガスの送出要求量が減少した場合には、前記液体酸素貯槽に貯溜されている液体酸素量を増やす一方で、液体酸素の気化に供せられ前記液体空気貯槽に貯溜される液体空気量を減少させるところに要旨が存在する。
【００１４】
上記本発明の制御運転方法を実施するに当たっては、前記低圧塔の塔底部の液体酸素濃度を測定しておき、該酸素濃度が所定値でない時は、該液体酸素濃度が所定値となる様に、低圧塔と液体酸素貯槽を結ぶ液体酸素抜出管路に設けた流量調節弁を制御できる様にすれば、製品酸素濃度を一層安定時維持することができるし、また、前記高圧塔底部における液体酸素の液面と液体酸素貯槽の液面および製品酸素送出量の予測値から、前記低圧塔で必要とされる寒冷のための液体空気量を算出し、圧縮／膨張器への原料空気の供給量を制御する様にすれば、制御運転をより安定に行なうことができるので好ましい。
【００１５】
そして上記制御運転方法によれば、基本的に製品酸素の送出要求量を入力するだけで、それに応じて予め設定されている演算式によって、前記原料空気量や、窒素リッチ液量、酸素リッチ液量、液体酸素量などを適切に予測制御することができ、あるいは更に、低圧塔の液体酸素濃度を実測し該濃度に応じて、液体酸素量調節器や原料空気量調節器、窒素リッチ液量調節器などを微調整することにより、送出される製品酸素ガスの酸素濃度を下げることなく、要求量に応じた製品酸素を安定して送出することができる。
【００１６】
【発明の実施の形態】
以下、実施例図面を参照しつつ本発明を具体的に説明するが、本発明はもとより図示例に制限されるわけではなく、前・後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。
【００１７】
図１は、本発明に係る空気分離装置を例示する概略説明図であり、原料空気は図面左上の原料空気圧縮機１によって例えば約６００ｋＰａ程度にまで圧縮され、続く冷却器２で常温付近にまで冷却され、次いで吸着精製装置３を通過することにより水分や炭酸ガスが除去された後、３つの方向に分岐して主熱交換器４、酸素蒸発器７および圧縮／膨張器１１方向へ送られる。
【００１８】
主熱交換器４へ送られた圧縮空気は、低圧塔９２の塔頂から送出される製品窒素により液化温度付近（約−１７０℃程度）まで冷却された後、高圧塔９１の底部へ供給される。
【００１９】
他方、酸素蒸発器７へ導かれる圧縮空気は、途中で圧縮機５により更に高圧に圧縮され、冷却器６を経て酸素蒸発器７へ供給され、ここで、液体酸素貯槽１０から送られてくる液体酸素を蒸発させて製品酸素（気体）とする一方、圧縮空気は液体空気となって液体空気貯槽８に貯留される。該液体空気貯槽８内の液体空気は、前記主熱交換器４を経て供給される空気（気体）と一定の比率で高圧塔９１の底部へ供給される。
【００２０】
また、圧縮／膨張器１１へ導かれた圧縮空気は、まず圧縮機１１ａ側に入って昇圧された後、後方冷却器３６で常温付近にまで冷却され、主熱交換器４で更に冷却されて主熱交換器４の中間部から抜き出された後、今度は膨張器１１ｂ側に入り、断熱膨張により減圧されると共に更に冷却されてから低圧塔９２の中間部へ供給される。
【００２１】
主熱交換器４と液体空気貯槽８とから特定比率で高圧塔９１の底部へ供給される空気（液体＋気体）のうち気体空気は、高圧塔９１内を上昇していく過程で冷却され、高沸点成分である酸素は凝縮し還流液となって流下し、残りの気体は窒素濃度が高められつつ塔頂へと上昇する。他方、塔内を流下する液体空気中に含まれる低沸点成分の窒素は気体となって高圧塔９１内を上昇するので、高圧塔９１の底部には酸素濃度の高められた液体空気が貯留することになる。
【００２２】
図２を参照してより詳細に説明すると、高圧塔９１に供給された空気（気体＋液体）のうち気体空気Ｖ１は、塔内を上昇する際に塔頂部からの還流液Ｌ１と接して冷却され、高沸点成分である酸素は液化し還流液Ｌ１と一緒に流下する一方、低沸点成分である窒素は気体空気Ｖ１と共に上昇する。こうして高圧塔９１の上部には窒素濃度の高い窒素リッチガスが滞留する。この窒素リッチガスは、管路９４ａにより低圧塔９２の底部に配置された主凝縮器９４へ導かれ、低圧塔９２の底部に溜まっている液体酸素により冷却されて液化し、管路９４ｂを降下して高圧塔９１の上部９３へ戻る。
【００２３】
そして、上記窒素リッチ液の一部は窒素リッチ液供給路９５により低圧塔９２の上部へ導かれ、残りは還流液Ｌ１として流下する。一方、高圧塔９１の底部に溜まった酸素リッチ液は、酸素リッチ液供給路（管路）９６を通して低圧塔９２の中間部へ供給される。ここで高圧塔９１の上部の窒素濃度を一定に維持するには、塔内を上昇する気体Ｖ１量と降下する液体Ｌ１量の比率を略一定に維持する必要がある。
【００２４】
次に低圧塔９２では、上部から供給される窒素リッチ液が塔内を流下していく過程で、低沸点成分の窒素は気化して塔頂部方向へ上昇し、高沸点成分の酸素は液状のままで流下する。一方、低圧塔９２の中間部に供給される酸素リッチ液も同様にして成分分離が行なわれ、窒素は塔頂部方向へ、酸素は塔底部方向へ移動する。
【００２５】
かくして、低圧塔９２の塔頂部には高濃度の気体窒素が溜り、塔底部には高濃度の液体酸素が溜まる。この際、塔底部の液体酸素濃度を一定に保つには、塔内を上昇する気体Ｖ２量と降下する液体Ｌ２量の比率、および上昇する気体Ｖ３量と降下する液体Ｌ３量の比率をほぼ一定に保たなければならない。
【００２６】
再び図１に基づいて説明すると、低圧塔９２底部に溜まった液体酸素は、液体酸素供給路（管路）９７を通して液体酸素貯槽１０へ導かれ、ここから酸素需要量に応じて管路９８から送出ポンプ１３で昇圧された後、酸素蒸発器７で圧縮空気との熱交換によって加熱されて気体となり、製品酸素供給路（管路）１００から製品酸素ガスとして送出される。他方、低圧塔９２塔頂部の気体窒素は、気体窒素供給路（管路）９９を通して主熱交換器４へ導かれ、圧縮空気との熱交換により加熱されてから製品窒素ガスとして送出される。
【００２７】
こうした空気分離装置の操業過程で、製品酸素ガスの需要量が変化したときの操作条件の変化について、需要量増大の要求があった場合を例にとって説明する。
【００２８】
図１において、製品酸素ガスの需要量が増加すると、その増加量に応じて酸素蒸発器７での加熱蒸発量を増大させるため、該酸素蒸発器７へ供給される圧縮空気量を増加しなければならない。このとき、圧縮／膨張器１１方向への圧縮空気量を変化させる必要はないので、主熱交換器４方向へ流れる圧縮空気量は減少する。しかし、酸素蒸発器７を経て送られてくる圧縮空気は、液体空気貯槽８で一旦貯溜された後、主熱交換器４を経て送られてくる圧縮空気と高圧塔９１の入口側で合流して供給されるので、該高圧塔９１への供給空気層量は一定に維持される。但し圧縮空気の一部は液化しているので、高圧塔９１へ流入する原料空気中の液体酸素の比率は増加する。
【００２９】
高圧塔９１に入った原料空気のうち、ガス状の空気は塔内を上昇するが、液体酸素の比率が増加した分だけその量は減少する。高圧塔９１内を上昇する空気は、前述した如く塔頂部で低圧塔９２底部の液体酸素と熱交換して凝縮し、その一部は液体窒素として抜出されて窒素リッチ液供給路（管路）９５から低圧塔９２の上部へ送られ、残部は高圧塔９１の還流液として流下する。このとき、高圧塔９１塔頂の窒素純度を維持するには、図２でも説明した如く、上昇する気体Ｖ１量と降下する液体Ｌ１量の比率を一定に保つ必要があるので、該比率が一定となる様に調節弁９５ａを調節する。それに伴って、低圧塔９２内の液体量（還流窒素量）Ｌ２は減少する。
【００３０】
低圧塔９２底部で蒸発した気体（酸素蒸気）Ｖ３量は、これを気化させるための気体Ｖ１量が減っているので減少するが、低圧塔９２底部の酸素純度を維持するには、ここでも上昇する気体Ｖ３量と降下する液体Ｌ３量の比率を一定に保つ必要があるので、結果的に降下する液体Ｌ３量も減少する。Ｌ３は、Ｌ２と高圧塔９１から管路９６を通して供給される液体空気ＬＡが合流したものであるが、Ｖ３とＬ３の比率を一定に保つための流量の制約から、ＬＡも減少させねばならない。一方、高圧塔９１底部に供給される原料空気中の液体酸素量は前述の如く増加しているので、高圧塔９１の底部には液体空気が溜まってくる。
【００３１】
同じ理由で、低圧塔９２の底部から抜出される液体空気量も減少させる必要がある。そしてこれら流量の変化量は、理論的にかなりの精度で前もって計算することができる。
【００３２】
この様な空気分離装置において、製品酸素の送出要求量が変化した場合に実施される具体的な制御運転は、次の様にして行なわれる。
【００３３】
即ち図１に示す如く、製品酸素ガス送出要求量の変動を指示する制御部Ｓから製品酸素送出要求量信号Ｓ１が酸素流量制御器１６に送信されると、その信号は制御器１６から送出ポンプ１３のバイパス弁１４ａへ送られ、該バイパス弁１４aの開度調整が行われ、この信号Ｓ１は同時に演算器１２（Ｃ１、Ｃ２、Ｃ３、Ｃ４）にも送られる。
【００３４】
演算器Ｃ１では、設定された製品酸素送出量に対応する酸素蒸発器７での圧縮空気の使用量を、例えば下記演算式(1)によって算出し、その値を圧縮空気量調節器１５へ指示して圧縮機５の動力を制御する。従って本例では、これら演算器Ｃ１と圧縮空気量調節器１５が、前記1)の圧縮空気量演算・制御部となる。
ＡHP＝β1Ｖ0……演算式(1)
式中、ＡHPは圧縮空気流量、Ｖ0は製品酸素送出流量、βは酸素圧力と空気圧力によって定まる定数（通常は１．３〜１．７の値）、をそれぞれ意味する。
【００３５】
演算器Ｃ２では、製品酸素送出量の変化に対応して高圧塔９１から低圧塔９２へ送る必要な窒素リッチ液量を、下記演算式(2)によって算出し、これを窒素リッチ液量調節器９５ｂに指示して調節弁９５ａの開度調整を行なうことにより、高圧塔９１から低圧塔９２へ送られる窒素リッチ液量を制御する。従って本例では、これら演算部Ｃ２、酸素リッチ液量調節器９５ｂ、調節弁９５ａなどが、前記2)の窒素リッチ液量演算・制御部となる。
ＬＮ＝｛Ａγ1−ＡTγ1−ＡHP（γ1−γ2）｝（1−α1）……演算式(2)
式中、ＬＮは窒素リッチ液量、Ａは原料空気流量、ＡTはタービン流量、γ1は主熱交換器を出る原料空気中の蒸気比（通常１〜０．９６）、γ2は高圧塔９１へ入る圧縮空気ＡHP中の蒸気比、α1は高圧塔９１における気液比（Ｌ1／Ｖ1）を意味する。
【００３６】
次に演算器Ｃ３では、製品酸素送出量の変化に対応して、高圧塔９１から低圧塔９２へ送る必要な酸素リッチ液量を下記演算式(3)によって算出し、この値を酸素リッチ液量調節器９６ｂに指示して調節弁９６ａの開度調整を行なう。従って本例では、これら演算器Ｃ３や酸素リッチ液量調節器９６ｂ、調節弁９６ａなどが、前記3)の酸素リッチ液量演算・制御部となる。
ＬＡ＝−[α3Ａ／ｎ＋ＬＮ(1−α3)(1−γ3)]／[(1−α3)(１−γ4)] ……演算式(3)
式中、ＬＡは酸素リッチ液量、α3は低圧塔９２の底部気液比、γ3は窒素リッチ液中の蒸気比、γ4は酸素リッチ液中の蒸気比、Ａは原料空気流量、ｎは原料空気量／平均酸素製造量（比）を意味する。
【００３７】
また演算器Ｃ４では、製品酸素送出量の変化に対応して低圧塔９２底部から液体酸素貯槽１０へ送られる液体酸素量を下記演算式(4)によって算出し、この値を液体酸素量調節器９７ｂに指示して調節弁９７ａの開度調整を行なう。従って本例では、これら演算器Ｃ４、液体酸素量調節器９７ｂ、調節弁９７ａなどが、前記4)の液体酸素量演算・制御部となる。
Ｏ＝Ａ／ｎ……演算式(4)
式中、Ｏは低圧塔９２から抜出される液体酸素流量、Ａは原料空気流量、ｎは原料空気量／平均酸素製造量（比）を意味する。
【００３８】
そして、例えば製品酸素要求量が増加した場合は、前述の如く圧縮空気量調節器１５の指示によって圧縮機５の動力を調整し、酸素蒸発器７へ送られる圧縮空気量を増大すると共に、窒素リッチ液量調節器９５ｂ、酸素リッチ液量調節器９６ｂおよび液体酸素量調節器９７ｂによって、調節弁９５ａ、９６ａ、９７ａを閉まる方向に制御すると、液体酸素貯槽１０では、供給されるよりも送出される液体酸素量の方が多くなるので、液体酸素貯槽１０の酸素貯留量は減少する。
【００３９】
一方、酸素蒸発器７方向へ供給される原料空気量は、主熱交換器４へ供給される原料空気量よりも多くなるが、高圧塔９１へ供給される主熱交換器４からの原料空気量と酸素蒸発器７から液体空気貯槽８を経由して供給される空気量との供給比は一定であるため、液体空気貯槽８における液体空気貯留量は増加する。
【００４０】
逆に製品酸素要求量が減少した場合には、上記制御および現象と反対の制御を行なうことにより、上記液体空気貯槽８と液体酸素貯槽１０が緩衝帯となって、製品酸素需要量の変動にもかかわらず、原則として必要以上に液体酸素貯槽１０を大きくすることなく、且つ製品酸素の濃度低下を招くことなく、空気分離装置全体としては常に効率の高い状態を維持しつつ制御運転を行なうことが可能となる。
【００４１】
このとき、製品酸素の品質管理をより向上させるため、上記予測制御によって製造された製品酸素の濃度を測定し、その測定結果に基づいて特定の調節器を用いて制御運転を行なういわゆるフィードバック制御を行なうことも極めて有効である。
【００４２】
例えば図３を参照して説明すると、低圧塔９２底部の液体酸素濃度を測定器９７ｃで測定しておき、該酸素濃度が所定の濃度となる様に調節弁９７ａの開度調整を行なったり、また、酸素蒸発器７により気化されて送出される製品酸素の温度を測定器５ｃで測定し、この温度が所定温度となる様に原料空気圧縮機５の動力を制御したり、あるいは更に、低圧塔９２頂部の気体窒素中の酸素濃度を測定器９５ｃで測定し、この酸素濃度が所定値となる様に調節弁９５ａの開度調整を行なう、などが好ましい実施形態として例示される。
【００４３】
本発明の制御運転方法を実施する際にこれらのフィードバック制御を併用すれば、製品酸素濃度の濃度変化をより少なくできるので好ましい。なお、これらのフィードバック制御と前記予測制御を同時に行なうときは、前記フィードバック制御を前記予測制御に優先して行なうことが望ましい。
【００４４】
また圧縮／膨張器１１へ供給する原料空気量を、低圧塔９２底部の液体酸素の液面、液体酸素貯槽１０の液面および製品酸素送出量の予測値から、低圧塔９２で必要な寒冷のための液体空気量を算出して制御することもできる。これにより、従来は運転員の手に委ねられていた原料空気供給量の調整を、円滑且つ迅速に制御することが可能となる。
【００４５】
図４は本発明の他の実施例を示すもので、基本的には前記図１に示した例と同じであるが、空気分離装置の構成が若干異なる。すなわち前述した空気分離装置では、酸素蒸発器７で液化した空気を液体空気貯槽８で貯溜することによって、製品酸素の需要量変動を吸収する構成を採用しているのに対し、本例の空気分離装置では、高圧塔９１底部に溜まる酸素リッチ液を酸素リッチ液貯槽部１７に貯溜させる構成を採用することで、製品酸素の需要量変動を吸収できる様にしている。
【００４６】
以下、図４に基づいて、先に挙げた空気分離装置とは異なる部分について説明する。なお、前記図１と同じ機器・設備には図１と同じ番号を付している。
【００４７】
この例では、主熱交換器４と酸素蒸発器７とから導かれた原料空気は、混合比率を調整されることなく高圧塔９１の底部へ供給される。高圧塔９１では、図２で説明した如く酸素リッチ液と窒素リッチガスとの蒸留分離が行われ、高圧塔９１の底部に酸素リッチ液が溜まる。この酸素リッチ液は管路１７ａを通して酸素リッチ液貯槽１７へ導かれ、ここから、ポンプ１８を経て調節弁９６ａにより流量調整されてから、低圧塔９２の中間部へ供給される。
【００４８】
この様な空気分離装置において、製品酸素の送出要求量が変化した場合、例えば送出要求量が増加した場合には、酸素リッチ液量調節器９６ｂによって調節弁９６ａを閉じる方向に調整されるが、高圧塔９１で生成される酸素リッチ液量は一定であるため、酸素リッチ液が余剰となる。そこで、該余剰の酸素リッチ液を酸素リッチ液貯槽１７に滞留させて吸収することにより、製品酸素需要量の変動に対応する。反対に製品酸素の送出要求量が減少した場合には、酸素リッチ液貯槽１７に蓄えた酸素リッチ液を供給することにより対応すればよい。
【００４９】
この制御例で対象とする空気分離装置の他の実施態様を図５に示す。この装置では、製品酸素の送出要求量変動により高圧塔９１で定量生成する酸素リッチ液量の過不足を、前記図４の例で別途設けた酸素リッチ液貯槽１７に代えて高圧塔９１の底部容積を大きくすることにより対応する。
【００５０】
即ち図５の装置では、精留塔９の高圧塔９１部分の底部を通常より長くし、酸素リッチ液が通常より多く貯溜できる様にしている。もちろん高圧塔９１の底部容積を大きくする形状であれば、その形状は一切制限されない。この様な構成とすることで、貯槽を新たに設けることなく酸素リッチ液量の過不足を吸収することができる。
【００５１】
また前述した様な本発明の基本思想を活かせば、この種の空気分離装置を用いて少量の高圧窒素を製品として得たい場合は、前述した様な液体酸素貯槽に代えて、高圧塔から低圧塔への還流窒素ラインの途中に液体窒素貯槽を設け、該貯槽から高圧窒素を製品として抜出す際に同様の制御法として活用することもできるし、更には、前述した様な液体酸素貯槽と上記の様な液体窒素貯槽を併設し、高圧酸素と高圧窒素を製品として同時並行的に製造する際の制御法として活かすことも可能となる。
【００５２】
【発明の効果】
本発明は以上の様に構成されており、ガスホルダーなどの設備を大型化することなく、需要量の変動周期が長い設備に対しても、酸素濃度や窒素濃度を低下させることなく製品酸素や製品窒素を安定して供給できる空気分離装置とその制御運転方法を提供し得ることになった。
【図面の簡単な説明】
【図１】 本発明の１実施例を示す説明図である。
【図２】 本発明に係る空気分離装置の精留塔における蒸留分離の説明図である。
【図３】 本発明に係る空気分離装置を用いたフィードバック制御法を例示する説明図である。
【図４】 本発明に係る他の空気分離装置と制御運転方法を例示する説明図である。
【図５】 本発明に係る更に他の空気分離装置と制御運転方法を例示する説明図である。
【符号の説明】
１ 原料空気圧縮機
４ 主熱交換器
５ 原料空気圧縮機
７ 酸素蒸発器
８ 液体空気貯槽
１０ 液体酸素貯槽
１１ 圧縮／膨張器
１１ｃ 寒冷供給路
１５ 原料空気量調節器
１７ 酸素リッチ液貯槽
９１ 高圧塔
９２ 低圧塔
９５ 窒素リッチ液供給路（管路）
９５ｂ 窒素リッチ液量調節器
９６ 酸素リッチ液供給路（管路）
９６ｂ 酸素リッチ液量調節器
９７ 液体酸素供給路（管路）
９７ｂ 液体酸素量調節器
９９ 気体窒素供給路（管路）
１００ 製品酸素供給路（管路）[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an air separation device for separating oxygen and nitrogen from raw material air and a control operation method thereof, and more specifically, in accordance with fluctuations in demand for oxygen and nitrogen, the fluctuation amount is absorbed, and The present invention relates to an air separation apparatus improved so that the operating state of the apparatus can be stably controlled, and a control operation method thereof.
[0002]
[Prior art]
  Factories that consume a large amount of oxygen, such as power generation facilities and steelworks, often have an oxygen production facility for oxygen self-sufficiency on site, and the most widely used oxygen production facility is air. This is an air separation apparatus that can obtain oxygen as a raw material and can obtain a large amount of nitrogen as a by-product. The oxygen separator has different oxygen production capacities depending on its scale and the performance of the incidental equipment, but the production capacity of the equipment is most enhanced when it is operated in a steady (optimum) condition specific to the equipment. At that time, the maximum production efficiency can be obtained.
[0003]
  On the other hand, when considering power generation facilities, the power demand varies greatly between daytime and nighttime, so the amount of oxygen gas used for IGCC (Integrated Gasification Combined Cycle) also varies greatly between daytime and nighttime. Therefore, usually, a storage facility is provided so as to absorb fluctuations in the amount of oxygen gas used, and a method is employed in which the air separation device is steadily operated under constant conditions as much as possible.
[0004]
  For example, a method of compressing product oxygen or product nitrogen sent from an air separation device with a compressor and temporarily storing it in a gas holder, and sending the required amount from the gas holder according to the demand amount of product oxygen or product nitrogen It is. According to this method, the air separation device can be steadily operated under certain conditions regardless of fluctuations in the demand amount of product oxygen and product nitrogen, and the production capacity inherent to the equipment can be utilized to the maximum. .
[0005]
  However, when oxygen is supplied as fuel for the gasification power plant, the oxygen demand fluctuation cycle is longer than when oxygen is supplied to, for example, a converter in a steel mill. The economic burden due to the increase in construction costs and equipment area cannot be neglected.
[0006]
  In order to solve such a problem, a method has been proposed in which oxygen and nitrogen are stored in a liquid, and the liquid oxygen and liquid nitrogen are heated and vaporized according to demand. However, in such a method, although it is possible to cope with fluctuations in oxygen demand relatively easily, the operating conditions of the rectification tower constituting the air separation facility and the gas flow rate in the expansion turbine and the main heat exchanger fluctuate. As a result, various problems such as “” are caused, which is a major cause of reducing the efficiency of the air separation device.
[0007]
  Therefore, in order to supply oxygen gas to equipment with a long fluctuation cycle of demand without an increase in the size of ancillary equipment such as a gas holder, the optimal amount of oxygen gas delivered according to the demand of product oxygen gas Ideally, the air separation device should be controlled and operated so that it can be secured.
[0008]
  However, the conventional control operation method is based on the premise that the air separation device is in steady operation under certain conditions, so that it can maintain and control the oxygen concentration during steady operation, but it responds to changes in the required amount of product oxygen. It is not considered to automatically change the operating conditions, and when changing the operating conditions, the operator first changes the operating conditions by manual operation and switches to automatic control when the operating state is stable Has been.
[0009]
  For this reason, in order to change an operating condition according to the required amount of product oxygen, an excessive burden is imposed on the worker, and it is not suitable for actual operation. In the air separation device, even when the operating conditions are changed, the response to the change appears very slowly. Therefore, as proposed so far, the feedback control that adjusts the regulator after the state change occurs. I can't respond enough.
[0010]
[Problems to be solved by the invention]
  The present invention has been made in view of the circumstances as described above, and its purpose is to increase the oxygen concentration even when applied to a facility with a long fluctuation cycle of demand without increasing the size of ancillary facilities such as a gas holder. Another object of the present invention is to provide an air separation device and a control operation method thereof that can stably supply product oxygen and product nitrogen according to the demand without reducing the nitrogen concentration.
[0011]
[Means for Solving the Problems]
  The air separation apparatus according to the present invention that has solved the above problems includes a high-pressure column and a low-pressure column that separate raw air into liquid oxygen and gaseous nitrogen, a liquid oxygen storage tank that stores the separated liquid oxygen, and In an air separation device equipped with an oxygen evaporator that uses compressed raw material air as a heat source and vaporizes liquid oxygen to produce product oxygen gas.
  A control unit for instructing a change in the required amount of product oxygen gas delivery, and an instruction from the control unitAn oxygen flow rate controller for controlling the flow rate of product oxygen delivered from the oxygen evaporator, and liquid air branched from the supply path of the raw material air and liquefied by heat exchange in the oxygen evaporator, and the stored liquid A liquid air storage tank for joining the air to the other branched raw material air and supplying it to the high-pressure tower,
  further,In response to the product oxygen flow rate instructed by the control unit,
  Calculate the required amount of compressed air supplied to the oxygen evaporator, The amount of compressed air introduced into the oxygen evaporatorCompressed air amount calculation / control unit to control, nitrogen rich liquid amount calculation / control unit to calculate and control the necessary nitrogen rich liquid amount sent from the high pressure column to the low pressure column, and necessary to be sent from the high pressure column to the low pressure column An oxygen-rich liquid amount calculation / control unit that calculates and controls the amount of oxygen-rich liquid, and a liquid oxygen amount calculation / control unit that calculates and controls the amount of liquid oxygen that is sent from the bottom of the low-pressure tower to the liquid oxygen storage tank. It has a gist.
[0012]
  In the air separation tank value of the present invention, as another component, a liquid oxygen concentration measuring device is provided at the bottom of the low pressure column, and the liquid oxygen extraction amount is adjusted in a line connecting the low pressure column and the liquid oxygen storage tank. A valve is provided so that the amount of liquid oxygen extraction can be adjusted according to the liquid oxygen concentration at the bottom of the low-pressure column, or an oxygen concentration measuring device is provided at the top of the low-pressure column and the high-pressure column and the low-pressure column are connected. A flow control valve is installed in the nitrogen-rich liquid pipe so that the amount of nitrogen-rich liquid from the high-pressure column to the low-pressure column can be adjusted according to the oxygen concentration at the top of the low-pressure column. Recommended as possible.
[0013]
  The control operation method according to the present invention includes a high-pressure column and a low-pressure column that separate raw air into liquid oxygen and gaseous nitrogen, and a liquid oxygen storage that stores the separated liquid oxygen.Tank and pressureAn oxygen evaporator that uses the compressed raw material air as a heat source and vaporizes liquid oxygen to produce product oxygen gas;The liquid air branched from the raw material air supply path and liquefied by heat exchange in the oxygen evaporator is stored, and the stored liquid air is merged with the other branched raw material air and supplied to the high pressure column. Liquid air storage tank forIn operating the air separation equipment provided,
  The product oxygen gasThe required raw material air amount to be sent to the oxygen evaporator, the required amount of nitrogen-rich liquid and oxygen-rich liquid sent from the high-pressure column to the low-pressure column, and the bottom of the low-pressure column The necessary amount of liquid oxygen sent to the liquid oxygen storage tank is calculated so that the concentration of the product oxygen gas becomes a predetermined value, and the control operation is performed based on the calculated value.Yes,
  When the required amount of product oxygen gas is increased, the amount of liquid oxygen stored in the liquid oxygen storage tank is reduced while the amount of liquid air increased due to vaporization of liquid oxygen is stored in the liquid air storage. When the required amount of product oxygen gas is reduced, the amount of liquid oxygen stored in the liquid oxygen storage tank is increased while the liquid air storage tank is used for vaporization of liquid oxygen. Reduce the amount of liquid air stored inThere is a gist there.
[0014]
  In carrying out the control operation method of the present invention, the liquid oxygen concentration at the bottom of the low pressure column is measured, and when the oxygen concentration is not a predetermined value, the liquid oxygen concentration is set to a predetermined value. If the flow rate control valve provided in the liquid oxygen extraction line connecting the low pressure column and the liquid oxygen storage tank can be controlled, the product oxygen concentration can be maintained at a more stable time, and at the bottom of the high pressure column, The amount of liquid air for cooling required in the low-pressure tower is calculated from the liquid oxygen liquid level, the liquid oxygen storage tank liquid level and the predicted value of the product oxygen delivery amount, and the raw material air to the compressor / expander is calculated. It is preferable to control the supply amount because the control operation can be performed more stably.
[0015]
  According to the above control operation method, basically, the required amount of product oxygen is input, and the raw material air amount, the nitrogen-rich liquid amount, the oxygen-rich liquid is calculated according to an arithmetic expression set in advance accordingly. The amount of liquid, the amount of liquid oxygen, etc. can be appropriately predicted and controlled, or the liquid oxygen concentration in the low-pressure column is measured and the liquid oxygen amount controller, raw material air amount controller, nitrogen-rich liquid amount is selected according to the concentration. By finely adjusting the regulator or the like, the product oxygen corresponding to the required amount can be stably delivered without lowering the oxygen concentration of the delivered product oxygen gas.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be specifically described with reference to the drawings of the embodiments. However, the present invention is not limited to the illustrated examples, and appropriate modifications are made within a range that can be adapted to the purpose described above and below. It is also possible to carry out and they are all included in the technical scope of the present invention.
[0017]
  FIG. 1 is a schematic explanatory view illustrating an air separation device according to the present invention. The raw material air is compressed to about 600 kPa, for example, by the raw material air compressor 1 at the upper left of the drawing, and is then brought to near room temperature by the subsequent cooler 2. After being cooled and then passed through the adsorption purification apparatus 3, moisture and carbon dioxide gas are removed and then branched in three directions and sent to the main heat exchanger 4, oxygen evaporator 7 and compressor / expander 11 direction. .
[0018]
  The compressed air sent to the main heat exchanger 4 is cooled to near the liquefaction temperature (about −170 ° C.) by the product nitrogen sent from the top of the low pressure column 92 and then supplied to the bottom of the high pressure column 91. The
[0019]
  On the other hand, the compressed air led to the oxygen evaporator 7 is compressed to a higher pressure by the compressor 5 on the way, supplied to the oxygen evaporator 7 through the cooler 6, and sent from the liquid oxygen storage tank 10 here. While liquid oxygen is evaporated to produce product oxygen (gas), the compressed air becomes liquid air and is stored in the liquid air storage tank 8. The liquid air in the liquid air storage tank 8 is supplied to the bottom of the high-pressure tower 91 at a constant ratio with the air (gas) supplied through the main heat exchanger 4.
[0020]
  Further, the compressed air introduced to the compressor / expander 11 first enters the compressor 11a side and is pressurized, then cooled to near normal temperature by the rear cooler 36, and further cooled by the main heat exchanger 4. After being extracted from the intermediate part of the main heat exchanger 4, this time it enters the expander 11 b side, is depressurized by adiabatic expansion and is further cooled before being supplied to the intermediate part of the low-pressure column 92.
[0021]
  Of the air (liquid + gas) supplied from the main heat exchanger 4 and the liquid air storage tank 8 to the bottom of the high pressure tower 91 at a specific ratio, the gaseous air is cooled in the process of rising in the high pressure tower 91, Oxygen, which is a high-boiling component, condenses and flows down as a reflux liquid, and the remaining gas rises to the top of the column while increasing the nitrogen concentration. On the other hand, the low-boiling component nitrogen contained in the liquid air flowing down in the tower becomes a gas and rises in the high-pressure tower 91, so that liquid air with an increased oxygen concentration is stored at the bottom of the high-pressure tower 91. It will be.
[0022]
  Describing in more detail with reference to FIG. 2, the gas air V1 out of the air (gas + liquid) supplied to the high-pressure tower 91 is cooled in contact with the reflux liquid L1 from the top of the tower as it rises in the tower. Then, oxygen as a high boiling point component liquefies and flows down together with the reflux liquid L1, while nitrogen as a low boiling point component rises with the gaseous air V1. Thus, a nitrogen rich gas with a high nitrogen concentration stays in the upper part of the high pressure column 91. This nitrogen-rich gas is led to the main condenser 94 disposed at the bottom of the low-pressure column 92 through the pipe 94a, cooled and liquefied by the liquid oxygen accumulated at the bottom of the low-pressure tower 92, and descends the pipe 94b. Return to the upper part 93 of the high-pressure tower 91.
[0023]
  A part of the nitrogen-rich liquid is guided to the upper part of the low-pressure column 92 through the nitrogen-rich liquid supply path 95, and the rest flows down as the reflux liquid L1. On the other hand, the oxygen-rich liquid accumulated at the bottom of the high-pressure column 91 is supplied to an intermediate portion of the low-pressure column 92 through an oxygen-rich liquid supply path (pipe) 96. Here, in order to keep the nitrogen concentration in the upper portion of the high-pressure column 91 constant, it is necessary to maintain the ratio of the amount of the gas V1 rising in the column and the amount of the liquid L1 falling substantially constant.
[0024]
  Next, in the low-pressure column 92, in the process in which the nitrogen-rich liquid supplied from the top flows down in the column, the low-boiling component nitrogen is vaporized and rises toward the top of the column, and the high-boiling component oxygen is liquid. It flows down as it is. On the other hand, the oxygen-rich liquid supplied to the intermediate portion of the low-pressure column 92 is similarly subjected to component separation, with nitrogen moving toward the column top and oxygen moving toward the column bottom.
[0025]
  Thus, high concentration gaseous nitrogen accumulates at the top of the low pressure column 92 and high concentration liquid oxygen accumulates at the bottom of the tower. At this time, in order to keep the liquid oxygen concentration at the bottom of the column constant, the ratio of the amount of gas V2 rising and the amount of liquid L2 falling and the ratio of the amount of gas V3 rising and the amount of liquid L3 falling are almost constant. Must be kept.
[0026]
  Referring again to FIG. 1, the liquid oxygen accumulated at the bottom of the low-pressure column 92 is led to the liquid oxygen storage tank 10 through the liquid oxygen supply path (pipe) 97, and from here, the pipe 98 is passed according to the oxygen demand. After the pressure is raised by the delivery pump 13, the oxygen evaporator 7 is heated by heat exchange with the compressed air to become a gas, and is sent out from the product oxygen supply path (pipe) 100 as product oxygen gas. On the other hand, the gaseous nitrogen at the top of the low-pressure column 92 is led to the main heat exchanger 4 through the gaseous nitrogen supply path (pipe line) 99, heated by heat exchange with the compressed air, and then sent out as product nitrogen gas.
[0027]
  In the operation process of such an air separation device, the change in the operating condition when the demand amount of the product oxygen gas changes will be described by taking as an example a case where there is a demand for an increase in the demand amount.
[0028]
  In FIG. 1, when the demand amount of product oxygen gas increases, the amount of compressed air supplied to the oxygen evaporator 7 must be increased in order to increase the heat evaporation amount in the oxygen evaporator 7 according to the increase amount. I must. At this time, since it is not necessary to change the amount of compressed air in the direction of the compressor / expander 11, the amount of compressed air flowing in the direction of the main heat exchanger 4 is reduced. However, the compressed air sent through the oxygen evaporator 7 is temporarily stored in the liquid air storage tank 8 and then merged with the compressed air sent through the main heat exchanger 4 at the inlet side of the high-pressure tower 91. Therefore, the amount of the air layer supplied to the high pressure column 91 is kept constant. However, since a part of the compressed air is liquefied, the ratio of liquid oxygen in the raw air flowing into the high-pressure column 91 increases.
[0029]
  Of the raw material air that has entered the high-pressure tower 91, gaseous air rises in the tower, but the amount decreases as the liquid oxygen ratio increases. The air rising in the high-pressure column 91 is condensed by exchanging heat with the liquid oxygen at the bottom of the low-pressure column 92 at the top of the column as described above, and a part thereof is extracted as liquid nitrogen and is supplied with a nitrogen-rich liquid supply channel (pipe). ) 95 to the upper part of the low-pressure column 92, and the remainder flows down as the reflux liquid of the high-pressure column 91. At this time, in order to maintain the nitrogen purity at the top of the high pressure column 91, it is necessary to keep the ratio of the rising gas V1 amount and the descending liquid L1 amount constant as described in FIG. The control valve 95a is adjusted so that Along with this, the liquid amount (reflux nitrogen amount) L2 in the low-pressure column 92 decreases.
[0030]
  The amount of gas (oxygen vapor) V3 evaporated at the bottom of the low-pressure column 92 decreases because the amount of gas V1 for vaporizing it decreases, but it increases again to maintain the oxygen purity at the bottom of the low-pressure column 92. Since it is necessary to keep the ratio of the amount of gas V3 to be lowered and the amount of liquid L3 to be lowered constant, the amount of liquid L3 to be lowered is also reduced as a result. L3 is a combination of L2 and the liquid air LA supplied from the high-pressure tower 91 through the pipe 96, but LA must also be reduced due to flow restriction to keep the ratio of V3 and L3 constant. On the other hand, since the amount of liquid oxygen in the raw air supplied to the bottom of the high-pressure column 91 has increased as described above, liquid air accumulates at the bottom of the high-pressure column 91.
[0031]
  For the same reason, it is necessary to reduce the amount of liquid air extracted from the bottom of the low pressure column 92. These changes in flow rate can then be calculated in advance with theoretically considerable accuracy.
[0032]
  In such an air separation device, the specific control operation performed when the required amount of product oxygen is changed is performed as follows.
[0033]
  That is, as shown in FIG. 1, when a product oxygen delivery request signal S1 is transmitted from the controller S instructing the fluctuation of the product oxygen gas delivery request to the oxygen flow controller 16, the signal is sent from the controller 16 to the delivery pump. 13, the opening degree of the bypass valve 14a is adjusted, and this signal S1 is simultaneously sent to the calculator 12 (C1, C2, C3, C4).
[0034]
  In the calculator C1, the amount of compressed air used in the oxygen evaporator 7 corresponding to the set product oxygen delivery amount is calculated by, for example, the following equation (1), and the value is instructed to the compressed air amount adjuster 15. Thus, the power of the compressor 5 is controlled. Accordingly, in this example, the calculator C1 and the compressed air amount adjuster 15 serve as the compressed air amount calculation / control unit of 1).
AHP= Β1V0...... Calculation formula (1)
Where AHPIs the compressed air flow, V0Is a product oxygen delivery flow rate, and β is a constant determined by the oxygen pressure and air pressure (usually a value of 1.3 to 1.7).
[0035]
  The computing unit C2 calculates the amount of nitrogen-rich liquid required to be sent from the high-pressure column 91 to the low-pressure column 92 in accordance with the change in the product oxygen delivery amount by the following equation (2). The amount of nitrogen-rich liquid sent from the high-pressure column 91 to the low-pressure column 92 is controlled by instructing to 95b and adjusting the opening of the control valve 95a. Therefore, in this example, the calculation unit C2, the oxygen rich liquid amount regulator 95b, the control valve 95a, and the like serve as the nitrogen rich liquid amount calculation / control unit of 2).
LN = {Aγ1-ATγ1-AHP(Γ1−γ2)} (1-α1) …… Expression (2)
In the formula, LN is a nitrogen-rich liquid amount, A is a raw material air flow rate, ATIs the turbine flow rate, γ1Is the steam ratio in the feed air leaving the main heat exchanger (usually 1 to 0.96), γ2Is compressed air A entering the high pressure column 91HPVapor ratio inside, α1Is the gas-liquid ratio (L1/ V1).
[0036]
  Next, the computing unit C3 calculates the amount of oxygen-rich liquid required to be sent from the high-pressure column 91 to the low-pressure column 92 in accordance with the change in the product oxygen delivery amount by the following equation (3). The amount adjuster 96b is instructed to adjust the opening of the control valve 96a. Therefore, in this example, the arithmetic unit C3, the oxygen rich liquid amount controller 96b, the control valve 96a, and the like serve as the oxygen rich liquid amount calculation / control unit of the above 3).
LA = − [αThreeA / n + LN (1−αThree) (1-γThree)] / [(1-αThree) (1-γFour)] …… Formula (3)
Where LA is the oxygen-rich liquid amount, αThreeIs the gas-liquid ratio at the bottom of the low pressure column 92, γThreeIs the vapor ratio in the nitrogen-rich liquid, γFourIs the vapor ratio in the oxygen-rich liquid, A is the raw material air flow rate, and n is the raw material air amount / average oxygen production amount (ratio).
[0037]
  The computing unit C4 calculates the amount of liquid oxygen sent from the bottom of the low pressure column 92 to the liquid oxygen storage tank 10 in accordance with the change in the product oxygen delivery amount by the following equation (4). 97b is instructed to adjust the opening of the control valve 97a. Accordingly, in this example, the calculator C4, the liquid oxygen amount adjuster 97b, the control valve 97a, and the like serve as the liquid oxygen amount calculation / control section of the above 4).
O = A / n ... Formula (4)
In the formula, O represents the flow rate of liquid oxygen withdrawn from the low-pressure column 92, A represents the feed air flow rate, and n represents the feed air amount / average oxygen production amount (ratio).
[0038]
  For example, when the required amount of product oxygen increases, the power of the compressor 5 is adjusted according to the instruction of the compressed air amount adjuster 15 as described above, the amount of compressed air sent to the oxygen evaporator 7 is increased, and nitrogen When the control valves 95a, 96a, and 97a are controlled to be closed by the rich liquid amount adjuster 95b, the oxygen rich liquid amount adjuster 96b, and the liquid oxygen amount adjuster 97b, the liquid oxygen storage tank 10 is sent out rather than being supplied. Therefore, the amount of oxygen stored in the liquid oxygen storage tank 10 decreases.
[0039]
  On the other hand, the amount of raw material air supplied in the direction of the oxygen evaporator 7 is larger than the amount of raw material air supplied to the main heat exchanger 4, but the raw material air from the main heat exchanger 4 supplied to the high-pressure tower 91. Since the supply ratio between the amount and the amount of air supplied from the oxygen evaporator 7 via the liquid air storage tank 8 is constant, the liquid air storage amount in the liquid air storage tank 8 increases.
[0040]
  Conversely, when the product oxygen demand is reduced, the liquid air storage tank 8 and the liquid oxygen storage tank 10 serve as a buffer zone by performing the control opposite to the above control and phenomenon, so that the product oxygen demand varies. Nevertheless, as a general rule, the air separation device as a whole should be controlled while maintaining a highly efficient state without increasing the liquid oxygen storage tank 10 more than necessary and without causing a decrease in the concentration of product oxygen. Is possible.
[0041]
  At this time, in order to further improve the quality control of product oxygen, so-called feedback control is performed in which the concentration of product oxygen produced by the predictive control is measured, and a control operation is performed using a specific regulator based on the measurement result. It is also very effective to do.
[0042]
  For example, referring to FIG. 3, the liquid oxygen concentration at the bottom of the low pressure column 92 is measured by the measuring device 97c, and the opening degree of the control valve 97a is adjusted so that the oxygen concentration becomes a predetermined concentration. Further, the temperature of the product oxygen vaporized and delivered by the oxygen evaporator 7 is measured by the measuring device 5c, and the power of the raw air compressor 5 is controlled so that this temperature becomes a predetermined temperature, or further, the low pressure A preferred embodiment includes measuring the oxygen concentration in the gaseous nitrogen at the top of the column 92 with a measuring device 95c and adjusting the opening of the control valve 95a so that the oxygen concentration becomes a predetermined value.
[0043]
  It is preferable to use these feedback controls together when carrying out the control operation method of the present invention because the change in the product oxygen concentration can be reduced. In addition, when performing these feedback control and the said prediction control simultaneously, it is desirable to perform the said feedback control prior to the said prediction control.
[0044]
  In addition, the amount of raw material air supplied to the compressor / expander 11 is calculated based on the liquid oxygen liquid level at the bottom of the low pressure column 92, the liquid level of the liquid oxygen storage tank 10, and the predicted value of the product oxygen delivery amount. Therefore, the amount of liquid air can be calculated and controlled. As a result, it is possible to smoothly and quickly control the adjustment of the supply amount of the raw material air, which has conventionally been entrusted to the operator.
[0045]
  FIG. 4 shows another embodiment of the present invention, which is basically the same as the example shown in FIG. 1, but the configuration of the air separation device is slightly different. That is, in the air separation device described above, the air liquefied by the oxygen evaporator 7 is stored in the liquid air storage tank 8 so as to absorb the fluctuation in the demand amount of product oxygen, whereas the air of this example is used. The separation device adopts a configuration in which the oxygen-rich liquid stored at the bottom of the high-pressure tower 91 is stored in the oxygen-rich liquid storage tank section 17 so that fluctuations in the demand amount of product oxygen can be absorbed.
[0046]
  Hereinafter, a different part from the air separation apparatus mentioned above is demonstrated based on FIG. The same equipment and facilities as in FIG. 1 are assigned the same numbers as in FIG.
[0047]
  In this example, the raw air introduced from the main heat exchanger 4 and the oxygen evaporator 7 is supplied to the bottom of the high-pressure column 91 without adjusting the mixing ratio. In the high pressure column 91, as described with reference to FIG. 2, the oxygen rich liquid and the nitrogen rich gas are distilled and separated, and the oxygen rich liquid is accumulated at the bottom of the high pressure column 91. This oxygen-rich liquid is guided to the oxygen-rich liquid storage tank 17 through the pipe line 17 a, and from there, the flow rate is adjusted by the control valve 96 a through the pump 18, and then supplied to the intermediate portion of the low-pressure column 92.
[0048]
  In such an air separation device, when the requested amount of product oxygen changes, for example, when the requested amount increases, the oxygen rich liquid amount regulator 96b adjusts the regulating valve 96a in the closing direction. Since the amount of oxygen-rich liquid produced in the high-pressure column 91 is constant, the oxygen-rich liquid becomes redundant. Therefore, the excess oxygen-rich liquid is retained in the oxygen-rich liquid storage tank 17 and absorbed to cope with fluctuations in the product oxygen demand. On the other hand, when the required amount of product oxygen is reduced, the oxygen-rich liquid stored in the oxygen-rich liquid storage tank 17 may be supplied.
[0049]
  FIG. 5 shows another embodiment of the air separation device targeted in this control example. In this apparatus, the excess or deficiency of the amount of oxygen-rich liquid that is quantitatively generated in the high-pressure column 91 due to fluctuations in the required amount of product oxygen is replaced with the oxygen-rich liquid storage tank 17 separately provided in the example of FIG. This can be done by increasing the volume.
[0050]
  That is, in the apparatus of FIG. 5, the bottom of the high-pressure column 91 portion of the rectifying column 9 is made longer than usual so that more oxygen-rich liquid can be stored than usual. Of course, as long as the bottom volume of the high-pressure tower 91 is increased, the shape is not limited. By setting it as such a structure, the excess and deficiency of oxygen rich liquid quantity can be absorbed, without providing a storage tank newly.
[0051]
  In addition, if the basic idea of the present invention as described above is utilized, if a small amount of high-pressure nitrogen is to be obtained as a product using this type of air separation device, a low-pressure column is used instead of the liquid oxygen storage tank as described above. A liquid nitrogen storage tank is provided in the middle of the reflux nitrogen line to the tower, and can be used as a similar control method when extracting high-pressure nitrogen from the storage tank as a product. The liquid nitrogen storage tank as described above is also provided, and it can be utilized as a control method when high-pressure oxygen and high-pressure nitrogen are simultaneously manufactured as products.
[0052]
【The invention's effect】
  The present invention is configured as described above, and without increasing the size of equipment such as a gas holder, even for equipment with a long fluctuation cycle of demand, without reducing the oxygen concentration or nitrogen concentration, It was possible to provide an air separation device capable of stably supplying product nitrogen and a control operation method thereof.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing one embodiment of the present invention.
FIG. 2 is an explanatory diagram of distillation separation in a rectification column of an air separation device according to the present invention.
FIG. 3 is an explanatory diagram illustrating a feedback control method using an air separation device according to the present invention.
FIG. 4 is an explanatory diagram illustrating another air separation device and a control operation method according to the present invention.
FIG. 5 is an explanatory view illustrating still another air separation device and control operation method according to the present invention.
[Explanation of symbols]
1 Raw material air compressor
4 Main heat exchanger
5 Raw material air compressor
7 Oxygen evaporator
8 Liquid air storage tank
10 Liquid oxygen storage tank
11 Compressor / Expander
11c Cold supply path
15 Raw material air volume controller
17 Oxygen rich liquid storage tank
91 High pressure tower
92 Low pressure tower
95 Nitrogen-rich liquid supply path (pipe)
95b Nitrogen rich liquid volume regulator
96 Oxygen rich liquid supply path (pipe)
96b Oxygen rich liquid volume regulator
97 Liquid oxygen supply channel (pipe)
97b Liquid oxygen regulator
99 Gaseous nitrogen supply (pipe)
100 Product oxygen supply channel (pipe)

Claims (6)

原料空気を液体酸素と気体窒素に分離する高圧塔と低圧塔と、分離された液体酸素を貯溜する液体酸素貯槽、および、圧縮された原料空気を熱源とし液体酸素を気化させて製品酸素ガスとする酸素蒸発器を備えた空気分離装置において、
製品酸素ガス送出要求量の変動を指示する制御部と、
該制御部からの指示により前記酸素蒸発器から送り出される製品酸素流量を制御する酸素流量制御器と、
原料空気の供給路から分岐され前記酸素蒸発器における熱交換によって液化された液体空気を貯溜するとともに、その貯溜したその液体空気を、分岐された他方の原料空気に合流させて前記高圧塔に供給するための液体空気貯槽とを有し、
さらに、前記制御部から指示される製品酸素流量に対応して、
酸素蒸発器へ供給される必要な圧縮空気量を演算し、前記酸素蒸発器に導入する圧縮空気量を制御する圧縮空気量演算・制御部と、
高圧塔から低圧塔へ送られる必要な窒素リッチ液量を演算し制御する窒素リッチ液量演算・制御部と、
高圧塔から低圧塔へ送られる必要な酸素リッチ液量を演算し制御する酸素リッチ液量演算・制御部と、
低圧塔底部から液体酸素貯槽へ送られる必要な液体酸素量を演算し制御する液体酸素量演算・制御部と、
を備えていることを特徴とする空気分離装置。A high-pressure column and a low-pressure column for separating raw material air into liquid oxygen and gaseous nitrogen, a liquid oxygen storage tank for storing the separated liquid oxygen, and product oxygen gas by vaporizing liquid oxygen using the compressed raw material air as a heat source In an air separation device equipped with an oxygen evaporator
A control unit for instructing a change in the required amount of product oxygen gas delivery;
And oxygen flow rate controller for controlling the product flow rate of oxygen fed from the oxygen evaporator by an instruction from the control unit,
The liquid air branched from the raw material air supply path and liquefied by heat exchange in the oxygen evaporator is stored, and the stored liquid air is merged with the other branched raw material air and supplied to the high-pressure tower. A liquid air storage tank for
Furthermore, in response to the product oxygen flow rate instructed from the control unit,
A required amount of compressed air supplied to the oxygen evaporator, and a compressed air amount calculation / control unit for controlling the amount of compressed air introduced into the oxygen evaporator ;
A nitrogen rich liquid amount calculation / control unit for calculating and controlling the amount of nitrogen rich liquid required to be sent from the high pressure column to the low pressure column;
An oxygen rich liquid amount calculation / control unit for calculating and controlling the amount of oxygen rich liquid required to be sent from the high pressure column to the low pressure column;
A liquid oxygen amount calculation / control unit for calculating and controlling the required amount of liquid oxygen sent from the bottom of the low-pressure tower to the liquid oxygen storage tank;
An air separation device comprising: 前記低圧塔の塔底部に液体酸素濃度測定器が設けられると共に、低圧塔と液体酸素貯槽を結ぶラインに液体酸素抜出量調節弁が設けられ、低圧塔底部の液体酸素濃度に応じて液体酸素抜出量を調節可能にした請求項１に記載の空気分離装置。  A liquid oxygen concentration measuring device is provided at the bottom of the low-pressure column, and a liquid oxygen extraction amount adjusting valve is provided at a line connecting the low-pressure column and the liquid oxygen storage tank. The air separation device according to claim 1, wherein the extraction amount is adjustable. 前記低圧塔の塔頂部に酸素濃度測定器が設けられると共に、高圧塔と低圧塔を結ぶ窒素リッチ液管路に流量調節弁が設けられ、低圧塔頂部の酸素濃度に応じて、高圧塔から低圧塔への窒素リッチ液量を調節可能にした請求項１または２に記載の空気分離装置。  An oxygen concentration measuring device is provided at the top of the low-pressure column, and a flow rate control valve is provided in a nitrogen-rich liquid pipe connecting the high-pressure column and the low-pressure column. The air separation device according to claim 1 or 2, wherein the amount of nitrogen-rich liquid to the tower is adjustable. 原料空気を液体酸素と気体窒素に分離する高圧塔および低圧塔と、分離された液体酸素を貯溜する液体酸素貯槽と、圧縮された原料空気を熱源とし液体酸素を気化させて製品酸素ガスとする酸素蒸発器と、原料空気の供給路から分岐され前記酸素蒸発器における熱交換によって液化された液体空気を貯留するとともに、貯留したその液体空気を、分岐された他方の原料空気に合流させて前記高圧塔に供給するための液体空気貯槽とを備えた空気分離装置を操業するに当たり、
該製品酸素ガスの送出要求量に対応して、前記酸素蒸発器へ送られる必要な原料空気量と、前記高圧塔から低圧塔へ送られる必要な窒素リッチ液および酸素リッチ液の量、および、低圧塔底部から液体酸素貯槽へ送られる必要な液体酸素の量を、前記製品酸素ガスの濃度が所定値となる様に夫々演算し、該演算値に基づいて制御運転を行ない、
製品酸素ガスの送出要求量が増加した場合に、前記液体酸素貯槽に貯溜されている液体酸素量を減らす一方で、液体酸素の気化に供せられて増加した液体空気を前記液体空気貯槽に貯蔵し、また、製品酸素ガスの送出要求量が減少した場合には、前記液体酸素貯槽に貯溜されている液体酸素量を増やす一方で、液体酸素の気化に供せられ前記液体空気貯槽に貯溜される液体空気量を減少させることを特徴とする空気分離装置の制御運転方法。A high pressure column and low pressure column for separating feed air into liquid oxygen and gaseous nitrogen, liquid oxygen savings tank for reserving the separated liquid oxygen, oxygen product gas feed air which is compressed by vaporizing liquid oxygen as a heat source An oxygen evaporator, and liquid air branched from the supply path of the raw material air and liquefied by heat exchange in the oxygen evaporator, and the stored liquid air is merged with the other branched raw material air In operating an air separation device having a liquid air storage tank for supplying to the high pressure tower ,
Corresponding to the required amount of product oxygen gas delivered, the necessary amount of raw material air sent to the oxygen evaporator, the amount of necessary nitrogen-rich liquid and oxygen-rich liquid sent from the high pressure column to the low pressure column, and the amount of liquid oxygen required to be sent from the low pressure column bottom to the liquid oxygen storage tank, said product concentration of oxygen gas is respectively computed as a predetermined value, the control operation line stomach based on the calculated value,
When the required amount of product oxygen gas is increased, the amount of liquid oxygen stored in the liquid oxygen storage tank is reduced, while the liquid air increased due to vaporization of liquid oxygen is stored in the liquid air storage tank. In addition, when the required amount of product oxygen gas is reduced, the amount of liquid oxygen stored in the liquid oxygen storage tank is increased while the liquid oxygen is vaporized and stored in the liquid air storage tank. A control operation method for an air separation device, characterized in that the amount of liquid air is reduced . 前記低圧塔の塔底部の液体酸素濃度を測定しておき、該酸素濃度が所定値でない時は、該液体酸素濃度が所定値となる様に、低圧塔と液体酸素貯槽を結ぶ液体酸素抜出管路に設けた流量調節弁を制御する請求項４に記載の制御運転方法。  The liquid oxygen concentration at the bottom of the low-pressure column is measured, and when the oxygen concentration is not a predetermined value, liquid oxygen is extracted from the low-pressure column and the liquid oxygen storage tank so that the liquid oxygen concentration becomes a predetermined value. The control operation method according to claim 4, wherein a flow control valve provided in the pipe is controlled. 前記高圧塔底部における液体酸素の液面と液体酸素貯槽の液面および製品酸素送出量の予測値から、前記低圧塔で必要とされる寒冷のための液体空気量を算出し、圧縮／膨張器への原料空気の供給量を制御する請求項４または５に記載の制御運転方法。  The amount of liquid air for cooling required in the low-pressure column is calculated from the liquid oxygen level at the bottom of the high-pressure column, the liquid level of the liquid oxygen storage tank, and the predicted value of product oxygen delivery, and the compressor / expander The control operation method according to claim 4 or 5, wherein the supply amount of the raw material air is controlled.
JP2001145547A 2001-05-15 2001-05-15 Air separation device and control operation method thereof Expired - Fee Related JP3884240B2 (en)

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