JP4104726B2 - Operation method of air liquefaction separator - Google Patents

Operation method of air liquefaction separator Download PDF

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Publication number
JP4104726B2
JP4104726B2 JP7269298A JP7269298A JP4104726B2 JP 4104726 B2 JP4104726 B2 JP 4104726B2 JP 7269298 A JP7269298 A JP 7269298A JP 7269298 A JP7269298 A JP 7269298A JP 4104726 B2 JP4104726 B2 JP 4104726B2
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reflux
flow rate
reflux liquid
column
crude argon
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JPH11270965A (en
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義行 桝井
茂 湯沢
孝一 岡本
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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
    • F25J3/04666—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system
    • F25J3/04672—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser
    • F25J3/04678—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser cooled by oxygen enriched liquid from high pressure column bottoms
    • 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
    • F25J3/04478—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 controlling purposes, e.g. start-up or back-up procedures
    • F25J3/04484—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 controlling purposes, e.g. start-up or back-up procedures for purity control during steady state operation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—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
    • F25J3/048—Argon recovery
    • 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)
  • Separation By Low-Temperature Treatments (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、空気液化分離装置の運転方法に関し、詳しくは、低温で空気を液化精留することにより、少なくともアルゴン（粗アルゴンを含む）を製品として採取する空気液化分離装置であって、製品需要の大幅な変動に迅速に対応することができる空気液化分離装置の運転方法に関する。
【０００２】
【従来の技術】
酸素，窒素，アルゴンといった工業ガスの多消費ユーザーである製鉄所や化学工場等においては、ガスの大幅な需要変動が頻繁に繰り返されることが多い。これに対応するため、これらの工業ガスの製造設備である空気液化分離装置には、製品量の大幅な増減に迅速に対応できる能力が求められている。
【０００３】
例えば、空気液化分離装置にガスホルダーや液化ガス貯槽のようなバックアップ設備を付設して製品ガスを貯留し、需要増大時には、前記バックアップ設備から製品ガスを補給し、需要減少時には、余剰の製品ガスをバックアップ設備に貯留するようにしている。しかし、製品ガスの大幅需要変動に対応するためには、大型のバックアップ設備を必要とし、需要減少時にバックアップ設備の貯留能力を超えた場合には、装置のターンダウンや製品ガスの放風を行わなければならなかった。
【０００４】
また、前記ガスホルダー方式においては、需要増の際にも製品ガスの供給圧力を確保するため、製品圧縮機の吐出圧力を製品の送ガスに必要な圧力よりも遥かに高い圧力に設定して運転するため、動力の無駄が大きいという問題点がある。一方、製品ガスを液化して貯留する方式では、製品ガスを液化する際に多大な動力を要するという問題がある。さらに、製品ガスの放風は、過剰な生産を意味し、明らかに無駄な動力を消費していることになる。
【０００５】
【発明が解決しようとする課題】
したがって、空気液化分離装置自身の能力として、需要の増減量に合わせて製品ガスの生産量を迅速に増減量できることが要求されるが、製品ガスの生産量を急激に増減量すると、製品純度が変動する不都合がある。
【０００６】
すなわち、蒸留塔の増減量操作を行う場合、上昇ガスの流量変化は、遅れが殆ど無いのに対し、還流液の流量は、時間的な遅れを伴って変化するため、蒸留塔の負荷を変更する場合には、還流液量を上昇ガス量より早く変化させるように制御系を設定するなどしてこのアンバランスを緩和し、製品純度の変動を抑えるようにしている。
【０００７】
しかし、製品ガスとしてアルゴンを生産する装置に設けられた粗アルゴン塔においては、上昇ガスの流量と還流液の流量とが、塔頂部に設けた粗アルゴン凝縮器で一意的に制御されているため、液量の変更とガス量の変更とに時間差を設けることができず、例えば、原料空気量比で毎分３％といった迅速な操業変更を行うと、製品アルゴンの純度が損なわれたり、純度が大きく変動したりするため、粗アルゴン塔の操業変更を迅速に行うことはできなかった。特に、規則充填物を使用した粗アルゴン塔は、棚段式のものに比べてより顕著に純度変動等を生じるため、増減量操作の迅速化にとって大きな制限となっている。
【０００８】
そこで本発明は、増減量操作時の粗アルゴン塔内で生じる還流比のアンバランスを緩和することにより、製品アルゴンをはじめとする各種製品ガスの純度変動を最小に抑えながら迅速に増減量操作を行うことができる空気液化分離装置の運転方法を提供することを目的としている。
【０００９】
【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装置の第１の運転方法は、下部塔，上部塔及び主凝縮蒸発器を有する複精留塔と、液化空気を液化寒冷源とするアルゴン凝縮器を塔頂部に有する粗アルゴン塔とを備え、該粗アルゴン塔に、粗アルゴン塔の還流液を貯溜する液溜を付設し、該液溜に前記粗アルゴン塔の還流液を導く還流液導入径路と、該液溜に貯溜された還流液を前記粗アルゴン塔に供給する還流液供給径路と、前記還流液導入径路及び還流液供給径路の少なくともいずれか一方に、該径路を流れる還流液の流量を調節する流量調節手段とを設け、圧縮，精製，冷却した原料空気を液化精留することにより、製品として少なくともアルゴンを採取する空気液化分離装置の運転方法において、前記粗アルゴン塔の還流液の少なくとも一部を前記液溜に貯溜し、該貯溜された還流液を、装置の運転状態に応じた流量で前記粗アルゴン塔に供給するとともに、前記空気液化分離装置が増量運転又は減量運転に移行する際における前記還流液の流量の増減速度を、前記アルゴン凝縮器の寒冷源となる液化空気の流量の増減速度よりも高くすることを特徴としている。
【００１０】
さらに、本発明の空気液化分離装置の第２の運転方法は、下部塔，上部塔及び主凝縮蒸発器を有する複精留塔と、液化空気を液化寒冷源とするアルゴン凝縮器を塔頂部に有する粗アルゴン塔とを備え、該粗アルゴン塔に、粗アルゴン塔の還流液を貯溜する液溜を付設し、該液溜に前記粗アルゴン塔の還流液を導く還流液導入径路と、該液溜に貯溜された還流液を前記粗アルゴン塔に供給する還流液供給径路と、前記還流液導入径路及び還流液供給径路の少なくともいずれか一方に、該径路を流れる還流液の流量を調節する流量調節手段とを設け、圧縮，精製，冷却した原料空気を液化精留することにより、製品として少なくともアルゴンを採取する空気液化分離装置の運転方法において、前記粗アルゴン塔の還流液の少なくとも一部を前記液溜に貯溜し、該貯溜された還流液を、装置の運転状態に応じた流量で前記粗アルゴン塔に供給するとともに、前記空気液化分離装置が増量運転又は減量運転に移行する際における前記還流液の流量の増減を、前記アルゴン塔の上昇ガス流の増減よりも先行させることを特徴としている。
【００１１】
また、第１及び第２の運転方法において、前記空気液化分離装置が減量運転に移行する際には、前記粗アルゴン塔に供給される還流液の流量を前記アルゴン凝縮器で生成される還流液の流量よりも減少させること、さらに、前記空気液化分離装置が増量運転に移行する際には、前記粗アルゴン塔に供給される還流液の流量を前記アルゴン凝縮器で生成される還流液の流量よりも増加させることを特徴としている。
【００１２】
【発明の実施の形態】
図１は、本発明の運転方法を実施する空気液化分離装置の一形態例を示す系統図である。この空気液化分離装置は、製品として粗アルゴンガス（ＲＡｒ），酸素ガス（ＧＯ２），窒素ガス（ＧＮ２）を生産するものであって、下部塔１，上部塔２及び主凝縮蒸発器３を有する複精留塔４と、アルゴン凝縮器５及び液溜６を有する粗アルゴン塔７と、各種ガスや液を熱交換させるための主熱交換器８及び過冷器９と、装置を所定の運転状態に制御するための各種制御手段とにより形成されている。
【００１３】
図示しない圧縮機で所定圧力に圧縮され、精製設備で精製された原料空気（ＡＩＲ）は、流量指示調節計（ＦＩＣ）１１により制御される調節弁１１Ｖを通って主熱交換器８に流入し、複精留塔４等から導出された各種低温ガスと熱交換を行って所定温度に冷却された後、経路５１を通って前記下部塔１の下部に導入される。
【００１４】
下部塔１に導入された原料空気は、塔内での精留操作によって塔頂部の窒素ガスと塔底部の酸素富化液化空気とに分離する。塔頂部の窒素ガスは、経路５２を経て前記主凝縮蒸発器３に導入され、上部塔底部の液化酸素と熱交換を行って液化し、その一部が経路５３に分岐する他は、経路５４を経て下部塔１の頂部に戻され、下部塔１の還流液となる。一方、前記経路５３に分岐した液化窒素は、過冷器９で冷却された後、流量調節計（ＦＣ）１２で調節される調節弁１２Ｖを通り、経路５５から上部塔２の頂部に導入されて上部塔２の還流液となる。
【００１５】
また、下部塔底部の酸素富化液化空気は、経路５６に抜出されて過冷器９で冷却され、下部塔底部の酸素富化液化空気量（液面高さ）を検出する液面調節計（ＬＣ）１３により制御される調節弁１３Ｖを通り、経路５７を通って上部塔２の中段に導入される。さらに、下部塔１の下段からは、塔内を流下する還流液の一部である液化空気が経路５８に抜出され、過冷器９で冷却された後、流量指示調節計（ＦＩＣ）１４により制御される調節弁１４Ｖを通り、前記アルゴン凝縮器５に寒冷源として導入される。アルゴン凝縮器５でアルゴンを凝縮させることにより気化した液化空気（空気）は、経路５９を経て上部塔２の中段部に導入される。
【００１６】
上部塔２に導入された前記経路５５からの液化窒素、前記経路５７からの酸素富化液化空気及び経路５９からの空気（気化した液化空気）は、上部塔２での精留操作により、塔頂部の窒素ガスと、塔底部の液化酸素とに分離する。
【００１７】
塔頂部の窒素ガスは、経路６０に抜出され、過冷器９の寒冷源となった後、主熱交換器８で原料空気を冷却することにより昇温し、流量調節計（ＦＣ）１５により制御される調節弁１５Ｖを通って経路６１から製品窒素ガス（ＧＮ２）として採取される。
【００１８】
また、塔底部の液化酸素は、主凝縮蒸発器３で前記窒素ガスと熱交換を行うことにより蒸発して酸素ガスとなり、一部が経路６２に抜出され、残部は上部塔２の上昇ガスとなる。経路６２に抜出された酸素ガスは、主熱交換器８で昇温した後、流量指示調節計（ＦＩＣ）１６により制御される調節弁１６Ｖを通って経路６３から製品酸素ガス（ＧＯ２）として採取される。塔底部の液化酸素の一部は、経路６４に抜出され、過冷器９を経た後、上部塔底部の液化酸素量（液面高さ）を検出する液面調節計（ＬＣ）１７により制御される調節弁１７Ｖを通り、経路６５から製品液化酸素（ＬＯ２）あるいは液化酸素中への炭化水素の濃縮を防止するための保安液化酸素として抜出される。
【００１９】
さらに、上部塔２の中段上部からは、不純窒素ガスが経路６６に抜出され、過冷器９及び主熱交換器８を経た後、上部塔２の塔頂部の圧力を検出する圧力調節計（ＰＣ）１８により制御される調節弁１８Ｖを通って経路６７から廃窒素ガス（ＲＮ２）として導出される。
【００２０】
そして、上部塔１の中段部からは、アルゴンを採取するための原料ガスとなるフィードアルゴンが経路６８に抜出され、流量計（ＦＩ）１９で流量を検出されながら粗アルゴン塔７の下部に導入され、粗アルゴン塔７の上昇ガスとなる。粗アルゴン塔７での精留によって塔頂部に発生した粗アルゴンガスは、経路６９を経てアルゴン凝縮器５に導入され、前記液化空気との熱交換によって大部分が液化し、該アルゴン凝縮器５と粗アルゴン塔７の頂部とを連結する液化アルゴン径路７０を形成する還流液導入径路７１，前記液溜６，還流液供給径路７２，調節弁２１Ｖを経て粗アルゴン塔７の塔頂部に導入され、粗アルゴン塔７の還流液となる。この還流液量を調節する流量調節手段である調節弁２１Ｖは、液溜６内の液面高さを検出する液面検出手段である液面調節計（ＬＣ）２０及び還流液供給径路７２を流れる還流液の流量を検出する流量検出手段である流量指示調節計（ＦＩＣ）２１によって制御される。また、粗アルゴン塔７の底部に流下した還流液（酸素富化液）は、経路７３によって上部塔２に戻される。採取される粗アルゴンガス（ＲＡｒ）は、液溜６の上部から経路７４に抜出され、主熱交換器８で昇温した後、流量指示調節計（ＦＩＣ）２２により制御される調節弁２２Ｖを通って経路７５から取出される。
【００２１】
このように、液化アルゴン径路７０の途中に液溜６を設けるとともに、該液溜６から粗アルゴン塔７に供給する還流液量を制御する流量指示調節計２１及び調節弁２１Ｖを設けたことにより、粗アルゴン塔７の還流液量を、装置の運転状態に応じて任意に設定することができる。すなわち、装置の増減量操作における還流液の変化量を上昇ガスの変化量に先行させて変化させることが可能となるので、塔内での精留操作を適正な状態に保つことができ、粗アルゴンの純度変動を低減できる。さらに、粗アルゴン塔７の運転状態によって影響を受ける上部塔２等も適正な運転状態に保つことができるので、製品酸素ガス等の純度変動も低減でき、各製品ガスの純度が、設定された純度以下に低下することがなくなる。
【００２２】
このように形成した空気液化分離装置において、製品ガスの生産量を増減する場合は、あらかじめ設定されたプログラムに応じて各調節計が各調節弁の開度を制御し、各経路を流れる気液の流量を増減することにより行われる。
【００２３】
例えば、１００％負荷の運転状態から７０％負荷の状態に減量する際には、原料空気供給ラインの流量指示調節計１１によって調節弁１１Ｖが絞られ、原料空気供給量が所定の減速度で７０％に減らされるとともに、所定のタイミングで各調節計及び調節弁が作動し、各部の気液の流量を、最終的に７０％負荷の状態に応じた流量に変更する。なお、７０％負荷のときの各部の流量は、単純に７０％になるわけではなく、各製品ガスの純度が所定純度を保てるように適当な流量に調節される。
【００２４】
表１は、１００％負荷における原料空気量が１０００００Ｎｍ３／ｈで、純度保証値９９．６ｖｏｌ％以上の製品酸素ガスの採取量が２１０００Ｎｍ３／ｈ、純度９７ｖｏｌ％以上の粗アルゴンガスの採取量が８７０Ｎｍ３／ｈであって、７０％負荷における原料空気量が７００００Ｎｍ３／ｈで、製品酸素ガスの採取量が１４６８０Ｎｍ３／ｈ、粗アルゴンガスの採取量が５２０Ｎｍ３／ｈに、それぞれ設定した装置において、各負荷で安定した状態で運転しているときの主要部の流量［Ｎｍ３／ｈ］と純度（ガス組成）［ｖｏｌ％］とを示すものである。
【表１】

Figure 0004104726
【００２５】
このような設定における装置において、液溜６や調節弁２１Ｖ等を設けた場合（本実施例）と、液溜等を設けない場合（従来例）とを比較した。なお、本実施例における増量運転時及び減量運転時の各気液の流量変化量は、液溜６から粗アルゴン塔７に供給する還流液の変化量のみを毎分２％に設定し、これ以外は全て毎分１％で変化させた（廃窒素ガスは圧力が一定になるように制御）。一方、液溜や調節弁が無い従来例における粗アルゴン塔７の還流液量は、アルゴン凝縮器５に導入される液化空気量に依存しており、還流液量の直接的な制御は行っていない（他は全て毎分１％）。
【００２６】
まず、７０％負荷から１００％負荷に増量運転を行う場合、上部塔１から経路６８を経て粗アルゴン塔７に供給されるフィードアルゴン中のアルゴン濃度は、本実施例では、増量開始後約４０分で極小値約６ｖｏｌ％になり、以後漸増して所定の９．４３ｖｏｌ％に到達したのに対し、従来例では、約４０分後に極小値約５ｖｏｌ％になった。
【００２７】
経路７５から採取される粗アルゴン中の酸素濃度は、本実施例では、増量開始後約６時間で極大値約２．２ｖｏｌ％になり、以後非常にゆっくりと減少していったのに対し、従来例では、約４時間後に極大値約５ｖｏｌ％になった。また、粗アルゴン中の窒素濃度は、本実施例では、増量開始後約３０分で極大値約０．６ｖｏｌ％になり、すぐに元に戻ったが、従来例では、増量開始後約２時間からゆっくりと変化した。
【００２８】
経路６３から採取される製品酸素ガスの純度は、本実施例では、増量開始後約２時間で極大値約９９．８３ｖｏｌ％になり、従来例では、約２時間後に極大値約９９．８５ｖｏｌ％になり、両者共、以後漸減していった。
【００２９】
次に、１００％負荷から７０％負荷に減量運転を行う場合、前記フィードアルゴン中のアルゴン濃度は、本実施例では、減量開始後約３０分で極小値約６ｖｏｌ％になり、全体としてみるとほとんど変動しなかったのに対し、従来例では、約４０分後に極大値約２０ｖｏｌ％になり、以後２時間程度で所定値に戻った。
【００３０】
前記粗アルゴン中の酸素濃度は、本実施例ではほとんど変動しなかったのに対し、従来例では、約８０分後に極小値約０．７ｖｏｌ％になり、以後漸増していった。
【００３１】
前記製品酸素ガスの純度は、本実施例では、減量開始後約６０分で極大値約９９．８ｖｏｌ％になるが、全体としてみるとほとんど変動しなかったのに対し、従来例では、約１００分後に、保証値を下回る極小値約９９ｖｏｌ％になり、以後漸増していった。
【００３２】
上述の増量運転及び減量運転の状況をみると、従来例は、増量時に粗アルゴン中の酸素濃度が大きく上昇し、減量時に製品酸素ガスの純度が大きく低下している。これらの数値は、いずれも許容値や保証値を満足できるものではなく、流量の変動速度を毎分１％よりもかなり低く設定しなければならないことがわかる。一方、本実施例では、これらの濃度変動が抑制されており、許容値や保証値を十分に満足する数値となっている。
【００３３】
また、粗アルゴン塔７の還流液の変化速度を、他の変化速度より高く、特に、アルゴン凝縮器５に寒冷源として導入される液化空気の変化速度より高く設定することにより、還流液量の変化を上昇ガス量の変化に対応させることができるので、上述の濃度変動抑制効果が得られるだけでなく、従来に比べて全体の流量増減速度を高く設定することが可能となるので、増減量操作を迅速に行うことができる。
【００３４】
なお、定常運転時における粗アルゴン塔７の還流液量は、流量指示調節計２１によって還流液供給径路７２の流量を一定に保つようにしてしてもよく、液面調節計２０によって液溜６内の液面を一定に保つようにしてもよい。
【００３５】
また、図１に想像線で示すように、還流液導入径路７１と還流液供給径路７２とを接続し、液溜６をバイパスする経路７６及び弁７６Ｖを設け、この経路７６に一定量の還流液を流し、残部を流量調節用として液溜６を通すようにしても同様の効果が得られる。この場合は、液溜６等を小型化することができる。
【００３６】
図２は、本発明の運転方法を実施する空気液化分離装置の他の形態例を示す系統図である。この空気液化分離装置は、粗アルゴン塔３０を上下２層構造とし、上層の精留段３１の下方に、塔内を流下する還流液の少なくとも一部を抜取って液溜３２に導く還流液導入経路３３を接続し、下層の精留段３４の上方に、液溜３２内の還流液を塔内に供給する還流液供給経路３５を接続するとともに、該還流液供給経路３５に、液溜３３内の液面高さを検出する液面調節計（ＬＣ）３６及び還流液供給径路３５を流れる還流液の流量を検出する流量指示調節計（ＦＩＣ）３７によって制御される調節弁３７Ｖを設けたものである。
【００３７】
本形態例は、粗アルゴン塔３０を流下する還流液の一部又は全部を、還流液導入経路３３により塔外に抜出して液溜３２に貯留し、所定量の還流液を、還流液供給径路３５により液溜３２から粗アルゴン塔３０に供給するようにしたものであって、下層の精留段３４における還流液量を任意に設定できるように形成したものである。
【００３８】
したがって、本形態例においても、粗アルゴン塔全体の還流液量の調節はできないものの、下層の精留段３４を流下する還流液量を、装置の運転状態に応じて適切に調節することができるので、前記形態例と略同様の濃度変動抑制や増減量運転操作の迅速化を図ることができる。
【００３９】
また、本形態例では、還流液導入経路３３の抜取り量を一定とし、還流液供給径路３５に調節弁３７Ｖを設けて粗アルゴン塔３０への還流液供給量を調節するように形成したが、還流液供給径路３５に調節弁を設けず、還流液導入経路３３に調節弁を設け、粗アルゴン塔３０の中間から抜取る還流液量を調節するように形成しても、下層の精留段３４における還流液の量を任意に調節することができる。
【００４０】
なお、本形態例は、粗アルゴン塔３０及びその周辺の構成、粗アルゴンを採取する前記経路７４が、粗アルゴン塔３０の頂部とアルゴン凝縮器５とを接続するガス経路３８から分岐する点を除いては、図１に示した前記形態例と同一に形成しているので、前記形態例における構成要素と同一の構成要素には同一符号を付して詳細な説明は省略する。
【００４１】
また、規則充填物を使用した充填塔を粗アルゴン塔３０に使用する際には、上下の充填物の間に設けられている液体捕集分配装置における液体捕集部を液溜として利用し、液体捕集部と液体分配部と間や、液体分配部に適宜な流量制御手段を設けるようにしてもよく、あるいは、液体捕集部で捕集した還流液を外部の液溜に抜出し、外部の液溜から液体分配部に還流液を供給するように形成するとともに、抜出し部や供給部の適当な位置で流量制御を行うようにしてもよい。さらに、図１の構成と図２の構成とを併用してもよい。
【００４２】
【発明の効果】
以上説明したように、本発明は、原料ガス（フィードアルゴン）が下部から供給され、上部に還流液を生成する凝縮器を備えた粗アルゴン塔に液溜等を付設して還流液の流量を調節できるようにしたので、粗アルゴン塔内の上昇ガス量と還流液量とを別々に独立して操作することができ、装置の運転状態に応じて最適な還流液量に設定することができる。例えば、減量操作時には粗アルゴン塔へ供給する還流液を減量し、逆に増量操作時には粗アルゴン塔に供給する還流液の流量を迅速に増量させることができるため、粗アルゴン塔内の上昇ガスと還流液との増減速度のアンバランスを緩和させることができ、製品純度の変動幅を小さく抑えることができるとともに、増減量操作を迅速に行うことができる。
【図面の簡単な説明】
【図１】 本発明の運転方法を実施する空気液化分離装置の一形態例を示す系統図である。
【図２】 同じく他の形態例を示す系統図である。
【符号の説明】
１…下部塔、２…上部塔、３…主凝縮蒸発器、４…複精留塔、５…アルゴン凝縮器、６…液溜、７…粗アルゴン塔、８…主熱交換器、９…過冷器、１１Ｖ〜２２Ｖ…調節弁、７０…液化アルゴン径路、７１…還流液導入径路、７２…還流液供給径路、ＦＩＣ…流量指示調節計、ＬＣ…液面計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of operating a cryogenic air separation equipment, particularly, by liquefying rectification of air at low temperature, a cryogenic air separation unit for collecting at least argon (containing the crude argon) as a product, the product to a method for operating a cryogenic air separation equipment that can quickly respond to large fluctuations in demand.
[0002]
[Prior art]
In steelworks and chemical factories, etc., which are users of many industrial gases such as oxygen, nitrogen, and argon, large fluctuations in gas demand are often repeated. In order to cope with this, an air liquefaction separation apparatus, which is a production facility for these industrial gases, is required to have a capability of quickly responding to a large increase or decrease in product quantity.
[0003]
For example, a backup facility such as a gas holder or a liquefied gas storage tank is attached to the air liquefaction separator to store product gas. When the demand increases, the product gas is replenished from the backup facility, and when the demand decreases, surplus product gas Are stored in backup equipment. However, large-scale backup equipment is required to cope with significant fluctuations in the demand for product gas. If the storage capacity of the backup equipment is exceeded when demand decreases, the equipment is turned down and product gas is vented. I had to.
[0004]
In addition, in the gas holder system, the discharge pressure of the product compressor is set to a pressure much higher than the pressure required for product gas supply in order to ensure the supply pressure of the product gas even when demand increases. There is a problem that the waste of power is large because of driving. On the other hand, the method of liquefying and storing the product gas has a problem that a great amount of power is required when the product gas is liquefied. Furthermore, the release of product gas means excessive production, which clearly consumes wasted power.
[0005]
[Problems to be solved by the invention]
Therefore, as the capacity of the air liquefaction separation device itself, it is required that the production amount of product gas can be increased or decreased quickly according to the increase or decrease amount of demand. However, if the production amount of product gas is increased or decreased rapidly, the product purity is reduced. There are inconveniences that fluctuate.
[0006]
In other words, when increasing / decreasing the distillation column, the flow rate of the rising gas has almost no delay, while the flow rate of the reflux liquid changes with a time delay, so the load on the distillation column is changed. In this case, the control system is set so that the amount of the recirculated liquid is changed faster than the amount of the rising gas, so that this unbalance is alleviated and the fluctuation of the product purity is suppressed.
[0007]
However, in the crude argon tower provided in the apparatus for producing argon as the product gas, the flow rate of the rising gas and the flow rate of the reflux liquid are uniquely controlled by the crude argon condenser provided at the top of the tower. However, there is no time difference between the change in the liquid amount and the change in the gas amount. For example, if a rapid operation change of 3% per minute in the raw material air volume ratio is performed, the purity of the product argon may be impaired, As a result, the operation of the crude argon column could not be changed quickly. In particular, a crude argon column using a regular packing produces a significant fluctuation in purity and the like as compared with a shelf type, and is thus a great limitation for speeding up the increase / decrease operation.
[0008]
Therefore, the present invention reduces the unbalance of the reflux ratio that occurs in the crude argon column during the increase / decrease operation, thereby allowing the increase / decrease operation to be performed quickly while minimizing fluctuations in the purity of various product gases including product argon. and its object is to provide a method of operating a cryogenic air separation equipment which can be carried out.
[0009]
[Means for Solving the Problems]
To achieve the above object, a first method of operation of the cryogenic air separation equipment of the present invention is a Fukusei column having a lower tower, upper column and a main condenser evaporator, the liquefied air and liquefied cooling source argon e Bei the crude argon column having a condenser at the top portion, reflux to the crude argon column, the reflux liquid of the crude argon column by attaching a liquid reservoir for reserving, leads to reflux of the crude argon column to the liquid reservoir flowing a liquid introduction path, a reflux liquid supply path for supplying the reflux liquid into the crude argon column which is reserved in the liquid reservoir, on at least one of the reflux liquid introduced path and a reflux solution supply path, the diameter passage setting the flow rate adjusting means for adjusting the flow rate of the reflux liquid only, compression, purification by a cooled feed air to liquefy rectification method of operating a least an air separation plant for collecting argon as product, wherein the crude Less reflux in the argon tower Is also stored in the liquid reservoir, and the stored reflux liquid is supplied to the crude argon tower at a flow rate corresponding to the operation state of the apparatus, and the air liquefaction separation apparatus shifts to an increase operation or a decrease operation. In this case, the rate of increase / decrease in the flow rate of the reflux liquid is set to be higher than the rate of increase / decrease in the flow rate of the liquefied air that serves as a cooling source for the argon condenser .
[0010]
Further, a second method of operation of the cryogenic air separation equipment of the present invention, the top part and Fukusei column, the argon condenser for liquefied air and the liquefied cooling source having a lower tower, upper column and a main condenser evaporator A crude argon tower, and a liquid reservoir for storing the reflux liquid of the crude argon tower is attached to the crude argon tower, and a reflux liquid introduction path for introducing the reflux liquid of the crude argon tower to the liquid reservoir, At least one of the reflux liquid supply path for supplying the reflux liquid stored in the liquid reservoir to the crude argon tower, and the reflux liquid introduction path and the reflux liquid supply path, the flow rate of the reflux liquid flowing through the path is adjusted. In the operating method of the air liquefaction separation apparatus for collecting at least argon as a product by liquefying and rectifying raw material air that has been compressed, purified and cooled by providing a flow rate control means, at least a part of the reflux liquid of the crude argon tower The liquid And the stored reflux liquid is supplied to the crude argon tower at a flow rate corresponding to the operation state of the apparatus, and the reflux liquid is transferred when the air liquefaction separation apparatus shifts to an increase operation or a decrease operation. The flow rate is increased or decreased before the increase in the rising gas flow in the argon column .
[0011]
Further, in the first and second operation methods , when the air liquefaction separation apparatus shifts to the weight reduction operation, the flow rate of the reflux liquid supplied to the crude argon tower is set to the reflux liquid generated by the argon condenser. When the air liquefaction / separation apparatus shifts to an increase operation, the flow rate of the reflux liquid supplied to the crude argon tower is changed to the flow rate of the reflux liquid generated by the argon condenser. It is characterized by increased than.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system diagram showing an embodiment of an air liquefaction separation apparatus that implements the operation method of the present invention. This air liquefaction separation apparatus produces crude argon gas (RAr), oxygen gas (GO 2 ), and nitrogen gas (GN 2 ) as products, and includes a lower column 1, an upper column 2, and a main condensing evaporator 3. A double rectifying column 4 having a flow rate, a crude argon column 7 having an argon condenser 5 and a liquid reservoir 6, a main heat exchanger 8 and a supercooler 9 for exchanging various gases and liquids, and a predetermined apparatus. It is formed by various control means for controlling to the operating state.
[0013]
The raw material air (AIR) compressed to a predetermined pressure by a compressor (not shown) and purified by a purification facility flows into the main heat exchanger 8 through a control valve 11V controlled by a flow rate indicating controller (FIC) 11. Then, heat exchange is performed with various low temperature gases derived from the double rectifying column 4 and the like, and after cooling to a predetermined temperature, the gas is introduced into the lower portion of the lower column 1 through the path 51.
[0014]
The raw air introduced into the lower column 1 is separated into nitrogen gas at the top of the column and oxygen-enriched liquefied air at the bottom of the column by a rectification operation in the column. The nitrogen gas at the top of the column is introduced into the main condensing evaporator 3 via a path 52 and is liquefied by exchanging heat with liquefied oxygen at the bottom of the upper tower, and a part of the nitrogen gas branches into a path 53. Is returned to the top of the lower column 1 and becomes the reflux liquid of the lower column 1. On the other hand, the liquefied nitrogen branched into the path 53 is cooled by the supercooler 9, then passes through the control valve 12V adjusted by the flow rate controller (FC) 12, and is introduced from the path 55 to the top of the upper tower 2. Thus, the reflux liquid of the upper column 2 is obtained.
[0015]
Further, the oxygen-enriched liquefied air at the bottom of the lower column is extracted to the path 56 and cooled by the supercooler 9, and the liquid level adjustment for detecting the oxygen-enriched liquefied air amount (liquid level height) at the bottom of the lower column. It passes through the control valve 13 </ b> V controlled by the meter (LC) 13, passes through the path 57, and is introduced into the middle stage of the upper tower 2. Further, from the lower stage of the lower tower 1, liquefied air that is a part of the reflux liquid flowing down in the tower is extracted to the path 58 and cooled by the supercooler 9, and then the flow rate indicating controller (FIC) 14. It passes through the control valve 14V controlled by, and is introduced into the argon condenser 5 as a cold source. The liquefied air (air) vaporized by condensing argon with the argon condenser 5 is introduced into the middle stage of the upper tower 2 via the path 59.
[0016]
The liquefied nitrogen from the path 55 introduced into the upper column 2, the oxygen-enriched liquefied air from the path 57, and the air from the path 59 (vaporized liquefied air) are subjected to a rectification operation in the upper column 2 to It separates into nitrogen gas at the top and liquefied oxygen at the bottom of the column.
[0017]
The nitrogen gas at the top of the column is extracted to the path 60 and becomes a cooling source for the supercooler 9, and then the temperature is raised by cooling the raw air in the main heat exchanger 8, and the flow rate controller (FC) 15 Is taken as product nitrogen gas (GN 2 ) from the path 61 through the control valve 15V controlled by the above.
[0018]
The liquefied oxygen at the bottom of the column is evaporated by exchanging heat with the nitrogen gas in the main condensing evaporator 3 to become oxygen gas, a part of which is withdrawn into the path 62, and the remainder is the rising gas of the upper column 2. It becomes. The oxygen gas extracted into the path 62 is heated by the main heat exchanger 8, and then passes through a control valve 16V controlled by a flow rate indicating controller (FIC) 16, and then the product oxygen gas (GO 2 ) from the path 63. Collected as. A part of the liquefied oxygen at the bottom of the column is withdrawn to the path 64, and after passing through the supercooler 9, a liquid level controller (LC) 17 for detecting the liquefied oxygen amount (liquid level height) at the bottom of the upper column. It passes through the control valve 17V to be controlled, and is extracted from the path 65 as product liquefied oxygen (LO 2 ) or safety liquefied oxygen for preventing the concentration of hydrocarbons in the liquefied oxygen.
[0019]
Further, from the upper middle part of the upper column 2, impure nitrogen gas is extracted into the path 66, passes through the supercooler 9 and the main heat exchanger 8, and then detects the pressure at the top of the upper column 2. It is led out as a waste nitrogen gas (RN 2 ) from the path 67 through the control valve 18V controlled by the (PC) 18.
[0020]
Then, from the middle stage of the upper column 1, feed argon serving as a raw material gas for extracting argon is extracted into a path 68, and the flow rate is detected by a flow meter (FI) 19, and is placed below the crude argon column 7. It is introduced and becomes the rising gas of the crude argon column 7. The crude argon gas generated at the top of the column by rectification in the crude argon column 7 is introduced into the argon condenser 5 via the path 69, and most of the crude argon gas is liquefied by heat exchange with the liquefied air. Is introduced into the top of the crude argon column 7 via the reflux liquid introduction path 71 that forms a liquefied argon path 70 that connects the top of the crude argon tower 7, the liquid reservoir 6, the reflux liquid supply path 72, and the control valve 21 </ b> V. The reflux liquid of the crude argon tower 7 is obtained. The control valve 21V, which is a flow rate adjusting means for adjusting the amount of the recirculated liquid, has a liquid level controller (LC) 20 and a recirculating liquid supply path 72, which are liquid level detecting means for detecting the liquid level in the liquid reservoir 6. It is controlled by a flow rate indicating controller (FIC) 21 which is a flow rate detecting means for detecting the flow rate of the flowing reflux liquid. In addition, the reflux liquid (oxygen-enriched liquid) that has flowed down to the bottom of the crude argon column 7 is returned to the upper column 2 through the path 73. The collected crude argon gas (RAr) is withdrawn from the upper part of the liquid reservoir 6 to the path 74, heated by the main heat exchanger 8, and then controlled by a flow rate indicating controller (FIC) 22 to be controlled valve 22V. Through path 75.
[0021]
As described above, the liquid reservoir 6 is provided in the middle of the liquefied argon path 70, and the flow rate indicating controller 21 and the control valve 21V for controlling the amount of the reflux liquid supplied from the liquid reservoir 6 to the crude argon tower 7 are provided. The amount of reflux liquid in the crude argon tower 7 can be arbitrarily set according to the operating state of the apparatus. That is, since it is possible to change the amount of change in the reflux liquid in the increase / decrease operation of the apparatus in advance of the change amount of the rising gas, the rectification operation in the column can be maintained in an appropriate state, Variations in argon purity can be reduced. Furthermore, since the upper column 2 etc. affected by the operating state of the crude argon column 7 can also be maintained in an appropriate operating state, the purity fluctuation of the product oxygen gas and the like can be reduced, and the purity of each product gas is set. It will not drop below purity.
[0022]
In the air liquefaction separation apparatus formed in this way, when increasing or decreasing the production amount of product gas, each controller controls the opening of each control valve according to a preset program, and the gas-liquid flowing through each path This is done by increasing or decreasing the flow rate.
[0023]
For example, when reducing from a 100% load operation state to a 70% load state, the control valve 11V is throttled by the flow rate indicating controller 11 of the raw material air supply line, and the raw material air supply amount is 70 at a predetermined deceleration. In addition, the controller and the control valve are operated at a predetermined timing, and finally the gas-liquid flow rate of each part is changed to a flow rate corresponding to the state of 70% load. Note that the flow rate of each part at 70% load is not simply 70%, but is adjusted to an appropriate flow rate so that the purity of each product gas can be maintained at a predetermined level.
[0024]
Table 1 is a 100% raw material air amount load 100000 3 / h, amount of collected purity guaranteed amount of collected 99.6Vol% or more oxygen product gas 21000Nm 3 / h, purity 97 vol% or more of crude argon gas Is 870 Nm 3 / h, the raw material air amount at 70% load is 70000 Nm 3 / h, the product oxygen gas sampling rate is 14680 Nm 3 / h, and the crude argon gas sampling rate is set to 520 Nm 3 / h, respectively. The flow rate [Nm 3 / h] and the purity (gas composition) [vol%] of the main part when the apparatus is operated in a stable state with each load are shown.
[Table 1]
Figure 0004104726
[0025]
In the apparatus in such a setting, the case where the liquid reservoir 6 and the control valve 21V were provided (this example) was compared with the case where the liquid reservoir was not provided (conventional example). Note that the amount of change in the flow rate of each gas and liquid during the increase operation and the decrease operation in this embodiment is set to 2% per minute for only the change amount of the reflux liquid supplied from the liquid reservoir 6 to the crude argon tower 7. Except for the above, all were changed at 1% per minute (waste nitrogen gas was controlled so that the pressure was constant). On the other hand, the amount of the reflux liquid in the crude argon tower 7 in the conventional example without a liquid reservoir or a control valve depends on the amount of liquefied air introduced into the argon condenser 5, and direct control of the amount of reflux liquid is performed. None (all others are 1% per minute).
[0026]
First, when increasing operation from 70% load to 100% load, the argon concentration in the feed argon supplied from the upper column 1 via the path 68 to the crude argon column 7 is about 40 after the start of increasing in this embodiment. The minimum value was about 6 vol% in minutes, and then gradually increased to reach a predetermined 9.43 vol%, whereas in the conventional example, the minimum value was about 5 vol% after about 40 minutes.
[0027]
In the present example, the oxygen concentration in the crude argon collected from the path 75 reached a maximum value of about 2.2 vol% after about 6 hours from the start of the increase, and thereafter decreased very slowly. In the conventional example, the maximum value was about 5 vol% after about 4 hours. Further, in this example, the nitrogen concentration in the crude argon reached a maximum value of about 0.6 vol% in about 30 minutes after the start of the increase, and immediately returned to the original value, but in the conventional example, about 2 hours after the start of the increase. It changed slowly.
[0028]
In this example, the purity of the product oxygen gas collected from the path 63 reaches a maximum value of about 99.83 vol% after about 2 hours from the start of the increase, and in the conventional example, the maximum value of about 99.85 vol% after about 2 hours. Both of them gradually decreased thereafter.
[0029]
Next, when performing a weight reduction operation from a 100% load to a 70% load, the argon concentration in the feed argon becomes a minimum value of about 6 vol% in about 30 minutes after the start of the weight reduction in this example. In contrast, in the conventional example, the maximum value was about 20 vol% after about 40 minutes, and then returned to the predetermined value in about 2 hours.
[0030]
The oxygen concentration in the crude argon hardly changed in the present example, whereas in the conventional example, the minimum value was about 0.7 vol% after about 80 minutes and gradually increased thereafter.
[0031]
In the present example, the purity of the product oxygen gas reaches a maximum value of about 99.8 vol% after about 60 minutes from the start of weight reduction. After a minute, it reached a minimum value of about 99 vol% below the guaranteed value, and then gradually increased.
[0032]
Looking at the state of the above-described increase operation and decrease operation, in the conventional example, the oxygen concentration in the crude argon greatly increases when the amount is increased, and the purity of the product oxygen gas greatly decreases when the amount is decreased. None of these numerical values satisfy the allowable value or the guaranteed value, and it is understood that the flow rate fluctuation rate must be set considerably lower than 1% per minute. On the other hand, in this embodiment, these density fluctuations are suppressed, and the numerical values sufficiently satisfy the allowable value and the guaranteed value.
[0033]
Further, the change rate of the reflux liquid of the crude argon column 7, higher than the other rate of change, in particular, by setting higher than the change rate of the liquefied air to be introduced as a cooling source in the argon condenser 5, the reflux liquid volume Since the change can be made to correspond to the change in the rising gas amount, not only the above-described concentration fluctuation suppression effect can be obtained, but also the overall flow rate increase / decrease speed can be set higher than in the prior art. The operation can be performed quickly.
[0034]
The flow rate of the reflux liquid in the crude argon column 7 during steady operation may be maintained at a constant flow rate in the reflux liquid supply path 72 by the flow rate indicating controller 21, and the liquid level 6 may be maintained in the liquid reservoir 6. The liquid level inside may be kept constant.
[0035]
Further, as indicated by an imaginary line in FIG. 1, the reflux liquid introduction path 71 and the reflux liquid supply path 72 are connected, and a path 76 and a valve 76V that bypass the liquid reservoir 6 are provided. The same effect can be obtained by flowing the liquid and letting the remainder pass through the liquid reservoir 6 for adjusting the flow rate. In this case, the liquid reservoir 6 and the like can be reduced in size.
[0036]
FIG. 2 is a system diagram showing another embodiment of the air liquefaction separation apparatus for carrying out the operation method of the present invention. In this air liquefaction separation apparatus, the crude argon tower 30 has an upper and lower two-layer structure, and a reflux liquid that draws at least a part of the reflux liquid flowing down in the tower below the upper rectifying stage 31 and leads it to the liquid reservoir 32. An inlet path 33 is connected, and a reflux liquid supply path 35 for supplying the reflux liquid in the liquid reservoir 32 into the tower is connected above the lower rectifying stage 34, and a liquid reservoir is connected to the reflux liquid supply path 35. A liquid level controller (LC) 36 that detects the liquid level in the liquid 33 and a flow rate indicating controller (FIC) 37 that detects the flow rate of the reflux liquid flowing through the reflux liquid supply path 35 are provided. It is a thing.
[0037]
In this embodiment, a part or all of the reflux liquid flowing down the crude argon tower 30 is extracted outside the tower through the reflux liquid introduction path 33 and stored in the liquid reservoir 32, and a predetermined amount of reflux liquid is supplied to the reflux liquid supply path. 35 is supplied from the liquid reservoir 32 to the crude argon tower 30, and is formed so that the amount of the reflux liquid in the lower rectifying stage 34 can be arbitrarily set.
[0038]
Therefore, in this embodiment as well, although the amount of reflux liquid in the entire crude argon column cannot be adjusted, the amount of reflux liquid flowing down the lower rectification stage 34 can be appropriately adjusted according to the operating state of the apparatus. Therefore, concentration fluctuation suppression and increase / decrease operation can be speeded up in substantially the same manner as in the embodiment.
[0039]
Further, in this embodiment, the reflux liquid introduction path 33 is made constant, and the reflux liquid supply path 35 is provided with a control valve 37V to adjust the reflux liquid supply quantity to the crude argon tower 30. Even if a control valve is not provided in the reflux liquid supply path 35 but a control valve is provided in the reflux liquid introduction path 33 so that the amount of the reflux liquid extracted from the middle of the crude argon column 30 is adjusted, the lower rectification stage The amount of reflux in 34 can be adjusted arbitrarily.
[0040]
In this embodiment, the crude argon tower 30 and the surrounding configuration, the path 74 for collecting the crude argon branch from the gas path 38 connecting the top of the crude argon tower 30 and the argon condenser 5. Except for this, since it is formed in the same manner as the embodiment shown in FIG. 1, the same components as those in the embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0041]
In addition, when using a packed column using regular packing for the crude argon column 30, use the liquid collection unit in the liquid collection and distribution device provided between the upper and lower packings as a liquid reservoir, An appropriate flow rate control means may be provided between the liquid collection unit and the liquid distribution unit or in the liquid distribution unit. Alternatively, the reflux liquid collected by the liquid collection unit is extracted into an external liquid reservoir, The liquid recirculation liquid may be supplied from the liquid reservoir to the liquid distribution part, and the flow rate may be controlled at an appropriate position of the extraction part or the supply part. Furthermore, the configuration of FIG. 1 and the configuration of FIG. 2 may be used in combination.
[0042]
【The invention's effect】
As described above, in the present invention, the raw material gas (feed argon) is supplied from the lower part, and a liquid reservoir or the like is attached to the crude argon tower provided with the condenser for generating the reflux liquid at the upper part to control the flow rate of the reflux liquid. Since it can be adjusted, the amount of ascending gas and the amount of the reflux liquid in the crude argon column can be operated separately and independently, and the optimum amount of the reflux liquid can be set according to the operating state of the apparatus. . For example, since the reflux liquid supplied to the crude argon tower can be reduced during the reduction operation, and conversely, the flow rate of the reflux liquid supplied to the crude argon tower can be increased rapidly during the increase operation. The unbalance of the increase / decrease speed with the reflux liquid can be alleviated, the fluctuation range of the product purity can be suppressed, and the increase / decrease operation can be performed quickly.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of an air liquefaction separation apparatus that implements an operation method of the present invention.
FIG. 2 is a system diagram showing another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Lower column, 2 ... Upper column, 3 ... Main condensation evaporator, 4 ... Double rectification column, 5 ... Argon condenser, 6 ... Liquid reservoir, 7 ... Coarse argon column, 8 ... Main heat exchanger, 9 ... Supercooler, 11V to 22V ... control valve, 70 ... liquefied argon path, 71 ... reflux liquid introduction path, 72 ... reflux liquid supply path, FIC ... flow rate indicating controller, LC ... liquid level gauge

Claims (4)

下部塔，上部塔及び主凝縮蒸発器を有する複精留塔と、液化空気を液化寒冷源とするアルゴン凝縮器を塔頂部に有する粗アルゴン塔とを備え、該粗アルゴン塔に、粗アルゴン塔の還流液を貯溜する液溜を付設し、該液溜に前記粗アルゴン塔の還流液を導く還流液導入径路と、該液溜に貯溜された還流液を前記粗アルゴン塔に供給する還流液供給径路と、前記還流液導入径路及び還流液供給径路の少なくともいずれか一方に、該径路を流れる還流液の流量を調節する流量調節手段とを設け、圧縮，精製，冷却した原料空気を液化精留することにより、製品として少なくともアルゴンを採取する空気液化分離装置の運転方法において、前記粗アルゴン塔の還流液の少なくとも一部を前記液溜に貯溜し、該貯溜された還流液を、装置の運転状態に応じた流量で前記粗アルゴン塔に供給するとともに、前記空気液化分離装置が増量運転又は減量運転に移行する際における前記還流液の流量の増減速度を、前記アルゴン凝縮器の寒冷源となる液化空気の流量の増減速度よりも高くすることを特徴とする空気液化分離装置の運転方法。Lower tower includes a Fukusei tower having an upper column and a main condenser evaporator and a crude argon column having a top portion with argon condenser for liquefied air and the liquefied cooling source, into the crude argon column, the crude argon column A reflux reservoir for storing the reflux solution of the crude argon tower, a reflux fluid introduction path for leading the reflux solution of the crude argon tower to the reservoir, and a reflux solution for supplying the reflux liquid stored in the reservoir to the crude argon tower a supply path, to at least one of the reflux liquid introduced path and a reflux liquid supplied paths, only set a flow rate adjustment means for adjusting a flow rate of the reflux liquid flowing through the diameter passage, compression, purified, cooled feed air In the operation method of the air liquefaction separation apparatus for collecting at least argon as a product by liquefying and rectifying, at least a part of the reflux liquid of the crude argon tower is stored in the liquid reservoir, and the stored reflux liquid is Depending on the operating condition of the device The flow rate of the reflux liquid when the air liquefaction separation device shifts to the increase operation or the decrease operation is changed to the flow rate of the liquefied air that serves as a cold source for the argon condenser. An operating method of an air liquefaction separation apparatus , characterized by being higher than a flow rate increase / decrease speed . 下部塔，上部塔及び主凝縮蒸発器を有する複精留塔と、液化空気を液化寒冷源とするアルゴン凝縮器を塔頂部に有する粗アルゴン塔とを備え、該粗アルゴン塔に、粗アルゴン塔の還流液を貯溜する液溜を付設し、該液溜に前記粗アルゴン塔の還流液を導く還流液導入径路と、該液溜に貯溜された還流液を前記粗アルゴン塔に供給する還流液供給径路と、前記還流液導入径路及び還流液供給径路の少なくともいずれか一方に、該径路を流れる還流液の流量を調節する流量調節手段とを設け、圧縮，精製，冷却した原料空気を液化精留することにより、製品として少なくともアルゴンを採取する空気液化分離装置の運転方法において、前記粗アルゴン塔の還流液の少なくとも一部を前記液溜に貯溜し、該貯溜された還流液を、装置の運転状態に応じた流量で前記粗アルゴン塔に供給するとともに、前記空気液化分離装置が増量運転又は減量運転に移行する際における前記還流液の流量の増減を、前記アルゴン塔の上昇ガス流の増減よりも先行させることを特徴とする空気液化分離装置の運転方法。 A double rectification column having a lower column, an upper column and a main condensing evaporator, and a crude argon column having an argon condenser having liquefied air as a liquefied cold source at the top of the column; A reflux reservoir for storing the reflux solution of the crude argon tower, a reflux fluid introduction path for leading the reflux solution of the crude argon tower to the reservoir, and a reflux solution for supplying the reflux liquid stored in the reservoir to the crude argon tower At least one of the supply path and the reflux liquid introduction path and the reflux liquid supply path is provided with a flow rate adjusting means for adjusting the flow rate of the reflux liquid flowing through the path, so that the compressed, purified, and cooled raw material air is liquefied. In the operation method of the air liquefaction separation apparatus that collects at least argon as a product by distillation, at least a part of the reflux liquid of the crude argon tower is stored in the liquid reservoir, and the stored reflux liquid is stored in the apparatus. Depending on operating conditions And supplies to the crude argon column at a flow rate, the flow rate decrease of the reflux liquid at the time of the air separation plant is shifted to increase operation or turndown, prior to causing than decrease the rising gas stream of the argon column how the operation of the air separation plant you wherein a. 前記空気液化分離装置が減量運転に移行する際には、前記粗アルゴン塔に供給される還流液の流量を前記アルゴン凝縮器で生成される還流液の流量よりも減少させることを特徴とする請求項１又は２記載の空気液化分離装置の運転方法。 The flow rate of the reflux liquid supplied to the crude argon tower is made smaller than the flow rate of the reflux liquid generated by the argon condenser when the air liquefaction separation apparatus shifts to a weight reduction operation. how the operation of the air separation plant of claim 1 or 2, wherein. 前記空気液化分離装置が増量運転に移行する際には、前記粗アルゴン塔に供給される還流液の流量を前記アルゴン凝縮器で生成される還流液の流量よりも増加させることを特徴とする請求項１又は２記載の空気液化分離装置の運転方法。 The flow rate of the reflux liquid supplied to the crude argon tower is increased more than the flow rate of the reflux liquid generated in the argon condenser when the air liquefaction separation apparatus shifts to the increase operation. Item 3. A method for operating an air liquefaction separation apparatus according to Item 1 or 2 .
JP7269298A 1998-03-20 1998-03-20 Operation method of air liquefaction separator Expired - Fee Related JP4104726B2 (en)

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