JP2004019987A - Cryogenic air separation apparatus - Google Patents

Cryogenic air separation apparatus Download PDF

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JP2004019987A
JP2004019987A JP2002172856A JP2002172856A JP2004019987A JP 2004019987 A JP2004019987 A JP 2004019987A JP 2002172856 A JP2002172856 A JP 2002172856A JP 2002172856 A JP2002172856 A JP 2002172856A JP 2004019987 A JP2004019987 A JP 2004019987A
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oxygen
air
storage tank
amount
cold storage
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Jun Yoshida
吉田　純
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Hitachi Ltd
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Hitachi 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
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F25J3/04818—Start-up of the process
    • 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
    • F25J3/04157—Afterstage cooling and so-called "pre-cooling" of the feed air upstream the air purification unit and main heat exchange line
    • 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
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/30—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes
    • F25J2205/32—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes as direct contact cooling tower to produce a cooled gas stream, e.g. direct contact after cooler [DCAC]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/30—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes
    • F25J2205/34—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes as evaporative cooling tower to produce chilled water, e.g. evaporative water chiller [EWC]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • F25J2240/42—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval the fluid being air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/40—Processes or apparatus involving steps for recycling of process streams the recycled stream being air

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cryogenic air separation apparatus allowing automatic reduction of a start-up time even if frequently repeating start-up. <P>SOLUTION: In a start-up process, a total amount of an oxygen amount entering a cold insulation tank 5 and a total amount of an oxygen amount leaving the cold insulation tank 5 are automatically calculated inside a control computer 40, and a supply amount of material air is brought into an optimum state for the cold insulation tank start-up on the basis of automatic increase control, automatic closure of a material air start-up bypass valve, and automatic reduction control of a product oxygen extraction amount. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、酸素プラントや窒素発生装置等の深冷空気分離装置において、起動時の「液蓄積」、「純度整定」工程の起動時間短縮制御方法に関する。
【０００２】
【従来の技術】
吸着塔等で処理した原料空気を原料とし、深冷分離にて酸素や窒素等の製品ガスまたは液体を連続生産するプラントにおいては、プラント停止から再起動を行う場合に、比較的深冷部分が運転温度近くまで冷えた場合からの起動である「寒冷起動」と、常温近くから起動する「常温起動」に大別される。
【０００３】
いずれの場合も、停止状態から、保冷槽内部に原料空気を新たに吹き込むことにより、「冷却」、「蓄液」、「純度整定」、「目標製品量へ整定」の起動工程となるが、これらのうち、「冷却」と「蓄液」工程は、保冷槽の全系を所定の運転温度まで冷却し、液化空気や液化酸素、液化窒素を所定量蓄積する工程であり、これらは主に発生寒冷量に支配される。そのため、「冷却」と「蓄液」工程の時間短縮には、より多くの寒冷を供給することが一番の早道であり、これら工程の間には通常は１台で運転する膨張タービンを複数台起動する等の方策が取られる。
【０００４】
【発明が解決しようとする課題】
しかしながら、液体／ガス酸素を主に生産する深冷分離酸素プラントでは、上記の「冷却」と「蓄液」工程に続く、「純度整定」、「目標製品量へ整定」工程には必ず所定の製品純度になるまでの待ち時間が存在し、これら工程は寒冷支配から、原料と抜き出し量のマスバランス支配となる。このため、前段の「冷却」と「蓄液」工程を急ぐあまり、相対的に液体窒素を多く精留塔に供給過多になる傾向にあり、従って、逆に「純度整定」、「目標製品量へ整定」工程で余計に時間を要する結果になることが多い。
【０００５】
昨今の深冷空気分離プラントでは、夜間停止し、昼間のみ営業運転する様な頻繁に起動を繰り返す事例が多く、このため、毎回の起動時間を如何に迅速に、且つ、自動的に行う要求が高まっている。
【０００６】
前記の如き、深冷空気分離プラントの再起動、特に、一時的なプラント停止後の「寒冷起動」では「冷却」と「蓄液」工程が比較的短くて済むため、「純度整定」、「目標製品量へ整定」工程をいかに短時間で完了させるかが、全体の起動時間短縮につながる。
【０００７】
従来の自動起動の制御では、「冷却」、「蓄液」工程はそのプラントの持てる寒冷発生能力を最大限に供給する制御を組んでいるが、それに続く、「純度整定」や「目標製品量へ整定」工程の制御は、「冷却」、「蓄液」工程の延長であり、最適な時間短縮制御とはなっていないのが現実である。
【０００８】
従って、「冷却」、「蓄液」工程を急ぐあまり、窒素リッチになってしまった精留塔の「純度整定」や「目標製品量へ整定」は時間が経過するのを待つことになる。
【０００９】
定常運転においては、最適な原料空気量を自動的に制御するマスバランス制御が行われるが、「純度整定」や「目標製品量へ整定」工程では、時間短縮を目的としたマスバランス制御は行われていない。
【００１０】
本発明の目的は、上記課題を解決すべく、頻繁に起動を繰返したとしても、自動的にマスバランス制御を行って、起動時間短縮を可能にした深冷空気分離装置を提供することにある。
【００１１】
【課題を解決するための手段】
上記目的を解決するために、本発明は、原料空気量または酸素放出量を制御する制御回路と、プラントの起動過程において、保冷槽内の精留塔への酸素蓄積状態を自動計算し、該計算された酸素蓄積状態を最適に保つように前記制御回路による最適な原料空気量または最適な酸素放出量を自動で制御する機能を有する制御計算機とを備えた深冷空気分離装置である。
【００１２】
また、上記制御計算機において、制御指令結果から、目標とする純度整定までの到達時間も予測・表示可能な機能を持たせる。
【００１３】
【発明の実施の形態】
本発明に係る深冷空気分離装置の起動制御方法の実施の形態について図面を用いて説明する。
【００１４】
深冷空気分離プラントでは、例えば、夜間停止し、昼間のみ営業運転する様な頻繁に起動を繰り返すことが要求されるようになってきている。
【００１５】
本発明に係る最も簡単な実施の形態として、原料空気から酸素ガスと窒素ガスを分離する深冷空気分離装置について図１を用いて説明する。大気中の空気を吸入し、所定の圧力まで、原料空気圧縮機１で昇圧する。空気の分離は低温状態に保たれた保冷槽５の内部で行われるが、操作温度が−１７０℃〜−１８０℃となり、常温からこの温度に至る間に凝縮・固化する水分やＣＯ２成分等を除去する目的で、吸着塔６が設けられている。
【００１６】
一般に、原料空気圧縮機１で圧縮された空気は、約９０〜１００℃の温度で最終段吐出から出てくるが、吸着塔６での運転温度まで冷却するために、チラー水２２と冷却水２１と直接接触し熱交換を行う水洗冷却塔２で冷却され、原料空気は約１５℃以下に降下する。
【００１７】
水洗冷却塔２には、寒冷源として、クリーニングタワー等で冷却された「冷却水」２１と、蒸発冷却塔４で更に温度降下した「チラー水」２２が供給される。通常、水洗冷却塔２の頂部へ「チラー水」２２が、中間部へ「冷却水」２１が供給される。蒸発冷却塔４では、頂部へは冷却水２１が供給され、底部から乾燥した窒素ガスや廃窒素ガスを蒸発冷却塔用ガスライン２３を介して供給することにより、底部へ流下した冷却水の温度は低下し、「チラー水」２２として、上記水洗冷却塔２の頂部へ供給される。但し、プラントの起動過程においては、保冷槽５からの戻りガス（窒素ガスや廃窒素ガス）が蒸発冷却塔用ガスライン２３を介して十分に確保されないため、蒸発冷却塔起動用のガスとして、水洗冷却塔２の出口の原料空気をバイパス弁３を介してバイパスさせて一時的に使用する。これを「蒸発冷却塔起動バイパス」２４と称している。
【００１８】
そして、吸着塔６にて、原料空気中の水分やＣＯ２等の後段の深冷分離プロセスにとって障害となる成分を吸着除去する。一般に、吸着塔６は複数塔の切替式になっており、一定周期毎に吸着と再生のサイクルを繰り返して運転される。吸着塔６の再生には、乾燥した、保冷槽５からの戻り窒素ガスや廃窒素ガスを窒素・廃窒素ガスライン２８を介して再生ガスヒータ１３等の外部熱源にて加熱したものが導入される。但し、プラントの起動過程においては、保冷槽５からの戻りガス（窒素ガスや廃窒素ガス）が窒素・廃窒素ガスライン２８を介して十分に確保されないため、吸着塔６の再生ガス２５として、吸着塔６の出口の原料空気をバイパス弁７を介して窒素・廃窒素ガスライン２８にバイパスさせ、該ガスライン２８から再生ガスライン２５に供給して一時的に使用する。これを「吸着塔起動バイパス」２６として称している。なお、蒸発冷却塔４への原料空気の供給と、再生ガスライン２５への原料空気の供給は、蒸発冷却塔用ガスライン２３に設けた弁３１によって、それぞれのラインの圧力が適正になるように調整される。
【００１９】
吸着塔６を出た原料空気は、保冷槽（コールドボックス）５の空気熱交換器９を経て、精留塔１０へ送られるが、一部は寒冷発生用の膨張タービン８への空気として抽気される。空気熱交換器９では、原料空気が製品酸素ガスライン２７や窒素・廃窒素ガスライン２８における低温部からの戻り酸素ガスや窒素ガスまたは廃窒素ガス等と熱交換し、液化温度近くまで冷却される。
【００２０】
精留塔１０は、採取する製品の種類（酸素、窒素、アルゴン、希ガス）、圧力、純度や性状（液体状態かガス状態か）でその構成が異なるが、図１は最も簡単な酸素ガスと窒素ガスを採取する図としている。本発明では、保冷槽５の内部を規定するものでないので、説明を省略する。
【００２１】
図１に示す実施の形態では、プラントの起動過程においては、保冷槽５を運転温度の低温状態（−１８０℃程度）まで冷却する「冷却」工程に加えて、精留塔１０に具備される凝縮器１１部分に大量の液化酸素（または液化空気）を所定の液として確保する「蓄液」工程が必要である。
【００２２】
「冷却」工程の速さは、「冷却」工程における寒冷発生の能力（例えば、膨張タービン８の寒冷発生能力、外部からの液体窒素供給能力）と、許容できる各部の温度降下速度の兼ね合いで決まる。一方、「冷却」後の「蓄積」や「純度設定」工程の速さは、保冷槽５に対する、供給量と放出量のマスバランスで決まり、より多くの原料空気を保冷槽５へ供給することが重要となってくる。
【００２３】
ところが、主凝縮器１１の「蓄積」工程では、保冷槽５からの戻りガス（窒素ガスや廃窒素ガス）の量が十分に確保されないため、上記吸着塔６や蒸発冷却塔４のための乾燥ガスが不足となり、そのため、吸着塔起動バイパス弁７や蒸発冷却塔起動バイパス弁３を開けて、原料空気の一部を吸着塔再生用の再生ガスライン２５や、蒸発冷却塔用ガスライン２３に供給して消費することになり、この状況下におけるマスバランスは、次に示す（１）式〜（３）式の如き関係がある。
【００２４】
ＣｉｎＭｏ２＝Ｙｆｏ・（Ｆｍｃ−Ｆｅｖｂ−Ｆａｄｂ）　　　　　　　　　　　　（１）
Ｆｗｇ＝（Ｆｍｃ−Ｆｅｖｂ−Ｆａｄｂ）−　Ｆｅｏ２　　　　　　　　　　　　（２）
ＣｏｕｔＭｏ２＝Ｙｅｏ・（Ｆｅｏ２）＋　Ｙｅｗｇ・（Ｆｗｇ）　　　　　　　　　　（３）
Ｆｍｃは、計測されて制御計算機４０に入力される原料空気圧縮機１での、原料空気圧縮量（Ｎｍ３／ｈ）である。すなわち、Ｆｍｃは、原料空気圧縮機１から供給される圧縮された原料空気量（Ｎｍ３／ｈ）でもある。このように圧縮された原料空気量（Ｆｍｃ）は、制御計算機４０からの制御指令に基づいて容量制御弁３２を自動制御することによって調整することが可能である。
Ｆｅｖｂは、計測されて制御計算機４０に入力される蒸発冷却塔起動バイパス２４の空気量（Ｎｍ３／ｈ）である。
Ｆａｄｂは、計測されて制御計算機４０に入力される吸着塔起動バイパス２６の空気量（Ｎｍ３／ｈ）である。
Ｙｆｏは、計測されて制御計算機４０に入力される原料空気中の酸素組成（％Ｏ２）（通常約２１％）である。
ＣｉｎＭｏ２は、保冷槽５へ供給される酸素量（Ｎｍ３／ｈ）である。
Ｆｅｏ２は、計測されて制御計算機４０に入力される保冷槽５から抽気される製品酸素ライン２７からの放出量（Ｎｍ３／ｈ）である。この製品酸素の放出量（Ｆｅｏ２）は、制御計算機４０からの制御指令に基づいて製品放出弁２９を自動制御することによって調整することが可能である。
Ｙｅｏは、計測されて制御計算機４０に入力される同上ガス中の酸素組成（％Ｏ２）（通常、低純度の場合約８０％で、高純度の場合約９９．８％である。）　（起動時初期値から定格組成まで変化）
Ｆｗｇは、計測されて制御計算機４０に入力される保冷槽５から排出される窒素ガス（廃窒素）量（Ｎｍ３／ｈ）である。この窒素ガス（廃窒素）の放出量（Ｆｗｇ）は、制御計算機４０からの制御指令に基づいて窒素放出弁３０を自動制御することによって調整することが可能である。
Ｙｅｗｇは、計測されて制御計算機４０に入力される同上ガス中の酸素組成（％Ｏ２）である。（通常、１０％〜２０％程度である。）　（起動時初期値から定格組成まで変化）
ＣｏｕｔＭｏ２は、保冷槽５から排出される酸素量（Ｎｍ３／ｈ）である。
Ｃｇａｉｎは、保冷槽５の内部に蓄積される酸素量（Ｎｍ３／ｈ）である。
【００２５】
なお、Ｆｍｃ、Ｆｅｖｂ、Ｆａｄｂ、Ｆｅｏ２及びＦｗｇは、各バルブ回路から得られるデータを基に制御計算機４０が算出してもよい。
【００２６】
従って、このときの保冷槽５の内部に蓄積される酸素の総量は次に示す（４）式となる。
【００２７】
Ｃｇａｉｎ＝ＣｉｎＭｏ２　−　ＣｏｕｔＭｏ２　　　　　　　　　　　　　　　　（４）
「蓄積」工程の時間を短縮するには、如何に短時間に、保冷槽５の内部に酸素成分を取り込むかという方策、すなわちＣｇａｉｎを如何に大きくとるかに帰結する。しかしながら、プラントが「冷却」から「蓄液」への起動段階においては、上記の如く、吸着塔起動バイパス空気量（Ｆａｄｂ）および蒸発冷却塔起動バイパス空気量（Ｆｅｖｂ）として保冷槽５へ入る原料空気量が最も減少する段階であり、ＣｉｎＭｏ２の値が低くなる。一方、「蓄液」に連なる「純度整定」の工程では、所定の酸素純度に持っていくため、予め製品酸素ガスライン２７から一定量抽気し、なるべく定格に近い送出を確保しようとする傾向がある。このため、場合によっては、Ｃｇａｉｎの値が負となり（蓄積酸素量が逆転し）、起動時間を短縮するどころか、逆に主凝縮器１１の液体酸素量と濃度が悪化方向に陥り、起動が不可能な状態に至ることもある。
【００２８】
このような問題を回避し、起動時間を少しでも自動的に短縮する目的で、ＤＣＳ（分配制御システム：Ｄｉｓｔｒｉｂｕｔｅｄ　Ｃｏｎｔｒｏｌ　Ｓｙｓｔｅｍ）等の制御計算機４０は、上記（１）式に基く保冷槽５への供給空気の流量（供給酸素量（ＣｉｎＭｏ２））の自動計測、および、その時の保冷槽５からの放出製品酸素の量（Ｆｅｏ２）と純度（Ｙｅｏ）を計測し、自動的に、上記（２）式に基いて廃ガス量（Ｙｅｗｇ・（Ｆｗｇ））を計算すると同時に、上記（３）式に基いて保冷槽５から持ち去られる酸素量（ＣｏｕｔＭｏ２）を内部計算し、上記（４）式に基いて保冷槽５の内部への酸素蓄積量（Ｃｇａｉｎ）を計算させる。制御計算機４０は、この求められた酸素蓄積量（Ｃｇａｉｎ）により、以下の制御動作を自動で行う。
（１）制御計算機４０は、逐一計算された保冷槽５への酸素蓄積量（Ｃｇａｉｎ）が所定の値以上の場合には、計測される現状の主凝縮器１１の液面値と計測される製品酸素の純度（Ｙｅｏ）から、「蓄液」「純度整定」の完了予測時間を計算し、表示装置４１の画面上に表示する。もし、完了予測時間が悪い場合には、制御計算機４０は、上記（１）式に基いて、原料空気圧縮機１から供給される原料空気圧縮量（Ｆｍｃ）を増やすように容量制御弁３２を含む制御回路を制御するか、または上記（３）式に基く保冷槽５から排出される酸素量（ＣｏｕｔＭｏ２）の主たる要素となる保冷槽５から抽気される製品酸素の放出量（Ｆｅｏ２）を減ずるように製品放出弁２９を含む制御回路を制御する。また、吸着塔再生ガス圧力が許す限りで、下流側の条件を満足していれば（保冷槽５から排出される窒素ガス（廃窒素）量が必要な流量確保できれば）、上記（１）式に基いて「起動バイパス回路」２６または２４において起動バイパス弁７または３を閉止方向へ制御して吸着塔起動バイパスの空気量（Ｆａｄｂ）または蒸発冷却塔起動バイパスの空気量（Ｆｅｖｂ）を減少させることも可能である。
（２）制御計算機４０は、逐一計算された保冷槽５への酸素蓄積量（Ｃｇａｉｎ）が所定の値以下の場合には、酸素蓄積量（Ｃｇａｉｎ）が所定の値に回復するまで、上記（１）式に基いて、原料空気圧縮機１から供給される原料空気圧縮量（Ｆｍｃ）を増やすように容量制御弁３２を含む制御回路を制御するか、または上記（３）式に基く保冷槽５から排出される酸素量（ＣｏｕｔＭｏ２）の主たる要素となる保冷槽５から抽気される製品酸素の放出量（Ｆｅｏ２）を減ずるように製品放出弁２９を含む制御回路を制御する。
【００２９】
また、吸着塔再生ガス圧力が許す限りで、下流側の条件を満足していれば（保冷槽５から排出される窒素ガス（廃窒素）量が必要な流量確保できれば）、「吸着塔起動バイパス回路」２６において起動バイパス弁７を閉止方向へ制御し、「蒸発冷却塔起動バイパス回路」２４において同様に、起動バイパス弁３を閉止方向へ制御して吸着塔起動バイパスの空気量（Ｆａｄｂ）または蒸発冷却塔起動バイパスの空気量（Ｆｅｖｂ）を減少させることも可能である。
【００３０】
なお、上記制御回路およびバイパス回路は、流量制御回路によって構成される。
（３）制御計算機４０は、逐一計算された保冷槽５への酸素蓄積量（Ｃｇａｉｎ）の値から判断して、起動が困難な状況（酸素蓄積量（Ｃｇａｉｎ）が０以下（負）で）の場合には警報発令と同時に、上記（２）の制御動作を実行し、一定時間経過しても、酸素蓄積量（Ｃｇａｉｎ）が０以上に回復しない場合（一定時間内に是正できない場合）には、プラント停止を促すメッセージ（起動中止要請のメッセージ）を制御計算機上において表示装置４１等の出力手段を用いて出力する。
【００３１】
以上説明したように、本発明の実施の形態によれば、起動過程における、保冷槽への酸素蓄積状況を逐次、自動的にモニタ、計算し、起動の状況が適切であるかを判断すると共に、プラント各部の状況が許す限り、酸素が蓄積しやすい状況を自動的に制御していく機能を持たせることにより、（１）プラント蓄液不能状態の即時検知・自動是正、（２）「蓄液」「純度整定」工程の所要時間の自動短縮制御、（３）良好な場合でも、計算した酸素蓄積状態から、完了時間の表示が可能となる。
【００３２】
【発明の効果】
本発明によれば、頻繁に起動を繰返したとしても、自動的にマスバランス制御を行って、起動時間短縮を可能にした深冷空気分離装置を実現することができる効果を奏する。
【図面の簡単な説明】
【図１】本発明に係る深冷空気分離装置の一実施の形態を示す構成図である。
【符号の説明】
１…原料空気圧縮機、２…水洗冷却塔、３…蒸発冷却塔起動バイパス弁、４…蒸発冷却塔、５…コールドボックス（保冷槽）、６…吸着塔、７…吸着塔起動バイパス弁、８…膨張タービン、９…空気熱交換器、１０…精留塔、１１…主凝縮器、１２…過冷却器、１３…再生ガスヒータ、１４…タービンライン、１５…保冷槽入口ライン、２１…冷却水、２２…チラー水、２３…蒸発冷却塔用ガスライン、２４…蒸発冷却塔起動バイパス回路、２５…再生ガスライン、２６…吸着塔起動バイパス回路、２７…製品酸素ガスライン、２８…窒素・廃窒素ガスライン、２９…製品放出弁、３０…窒素放出弁、３１…弁、３２…容量制御弁、４０…制御計算機、４１…表示装置。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control method for shortening the start-up time of “liquid accumulation” and “purity settling” processes at start-up in a cryogenic air separation apparatus such as an oxygen plant or a nitrogen generator.
[0002]
[Prior art]
In a plant that continuously produces product gas or liquid such as oxygen and nitrogen by deep cold separation using raw material air treated in an adsorption tower, etc. It is roughly divided into “cold start”, which is a start after cooling to near the operating temperature, and “normal start”, which starts from near room temperature.
[0003]
In either case, from the stopped state, the raw air is newly blown into the inside of the cold storage tank, which is the start-up process of `` cooling '', `` storage solution '', `` purity settling '', `` setting to the target product amount '' Of these, the “cooling” and “liquid storage” processes are processes that cool the entire system of the cold storage tank to a predetermined operating temperature and accumulate a predetermined amount of liquefied air, liquefied oxygen, and liquefied nitrogen. It is governed by the amount of cold generated. For this reason, the fastest way to reduce the time for the “cooling” and “storage” processes is to supply more cold air. During these processes, a plurality of expansion turbines that are usually operated by one unit are used. Measures such as starting the stand are taken.
[0004]
[Problems to be solved by the invention]
However, in a cryogenic separation oxygen plant that mainly produces liquid / gas oxygen, the “purity settling” and “set to target product” steps following the above “cooling” and “storage” steps must There is a waiting time until product purity is reached, and these processes are controlled by the mass balance between the raw material and the extraction amount from the control of the cold. For this reason, there is a tendency to excessively supply liquid nitrogen to the rectification column excessively, so that the “cooling” and “storage” processes in the previous stage are rushed. Therefore, conversely, “purity settling” and “target product quantity” In many cases, the “settling” process takes more time.
[0005]
In recent cryogenic air separation plants, there are many cases of frequent start-ups such as stopping at night and operating in the daytime, so there is a demand for how quickly and automatically start each time. It is growing.
[0006]
As described above, in the restart of the cryogenic air separation plant, in particular, in the “cold start” after the temporary stop of the plant, the “cooling” and “storage” processes are relatively short, so “purity settling”, “ How quickly the “set to target product quantity” process is completed leads to a reduction in overall startup time.
[0007]
In the conventional automatic start-up control, the “cooling” and “storage” processes are designed to supply the maximum cold generation capacity of the plant, followed by “purity settling” and “target product quantity”. The control of the “settling” process is an extension of the “cooling” and “liquid storage” processes, and is not actually an optimal time reduction control.
[0008]
Accordingly, the “purity settling” and “settling to the target product amount” of the rectification column that has become rich in nitrogen due to the rapid progress of the “cooling” and “storage” processes wait for the time to elapse.
[0009]
In steady operation, mass balance control is performed to automatically control the optimal amount of raw material air. However, mass balance control is performed to reduce time in the “purity settling” and “set to target product volume” processes. I have not been told.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide a cryogenic air separation device that automatically performs mass balance control and can shorten the start-up time even if the start-up is repeated frequently in order to solve the above problems. .
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned object, the present invention automatically calculates the oxygen accumulation state in the rectifying column in the cold storage tank during the start-up process of the plant and the control circuit that controls the amount of raw material air or the amount of released oxygen. A cryogenic air separation apparatus comprising a control computer having a function of automatically controlling an optimum raw material air amount or an optimum oxygen release amount by the control circuit so as to keep the calculated oxygen accumulation state optimum.
[0012]
The control computer has a function capable of predicting and displaying the arrival time from the control command result to the target purity settling.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a startup control method for a cryogenic air separation device according to the present invention will be described with reference to the drawings.
[0014]
In the cryogenic air separation plant, for example, it has been required to repeatedly start up, such as stopping at night and operating in the daytime.
[0015]
As a simplest embodiment according to the present invention, a cryogenic air separation device for separating oxygen gas and nitrogen gas from raw air will be described with reference to FIG. Air in the atmosphere is sucked and the pressure is increased by the raw material air compressor 1 to a predetermined pressure. Air separation is performed inside the cold storage tank 5 kept at a low temperature, but the operating temperature is -170 ° C to -180 ° C, and moisture, CO 2 components, etc. that condense and solidify from room temperature to this temperature. An adsorption tower 6 is provided for the purpose of removing water.
[0016]
In general, the air compressed by the raw material air compressor 1 comes out from the final stage discharge at a temperature of about 90 to 100 ° C. In order to cool to the operating temperature in the adsorption tower 6, chiller water 22 and cooling water are used. The raw air is lowered to about 15 ° C. or less as it is cooled by the water-washing cooling tower 2 that is in direct contact with the heat exchanger 21 for heat exchange.
[0017]
The water-washing cooling tower 2 is supplied with “cooling water” 21 cooled by a cleaning tower or the like and “chiller water” 22 having a further temperature drop in the evaporative cooling tower 4 as cold sources. Usually, “chiller water” 22 is supplied to the top of the flush cooling tower 2, and “cooling water” 21 is supplied to the middle part. In the evaporative cooling tower 4, the cooling water 21 is supplied to the top, and the temperature of the cooling water flowing down to the bottom is supplied by supplying dried nitrogen gas and waste nitrogen gas from the bottom through the evaporative cooling tower gas line 23. Is reduced and supplied as “chiller water” 22 to the top of the washing and cooling tower 2. However, in the start-up process of the plant, the return gas (nitrogen gas and waste nitrogen gas) from the cold storage tank 5 is not sufficiently secured through the evaporative cooling tower gas line 23. The raw material air at the outlet of the water-washing cooling tower 2 is bypassed via the bypass valve 3 and temporarily used. This is referred to as “evaporative cooling tower activation bypass” 24.
[0018]
Then, the adsorption tower 6 adsorbs and removes components that hinder the subsequent deep-cooling separation process such as moisture in the raw air and CO 2 . Generally, the adsorption tower 6 is a switching type of a plurality of towers, and is operated by repeating the adsorption and regeneration cycles at regular intervals. In the regeneration of the adsorption tower 6, dried dry nitrogen gas and waste nitrogen gas heated by an external heat source such as a regeneration gas heater 13 through a nitrogen / waste nitrogen gas line 28 are introduced. . However, in the start-up process of the plant, the return gas (nitrogen gas and waste nitrogen gas) from the cold storage tank 5 is not sufficiently secured through the nitrogen / waste nitrogen gas line 28, so that as the regeneration gas 25 of the adsorption tower 6, The raw material air at the outlet of the adsorption tower 6 is bypassed to the nitrogen / waste nitrogen gas line 28 via the bypass valve 7 and supplied from the gas line 28 to the regeneration gas line 25 to be temporarily used. This is referred to as “adsorption tower activation bypass” 26. It should be noted that the supply of the raw air to the evaporative cooling tower 4 and the supply of the raw air to the regeneration gas line 25 are performed so that the pressure of each line becomes appropriate by the valve 31 provided in the evaporative cooling tower gas line 23. Adjusted to
[0019]
The raw air leaving the adsorption tower 6 is sent to the rectification tower 10 through the air heat exchanger 9 in the cold storage tank (cold box) 5, but a part is extracted as air to the expansion turbine 8 for generating cold. Is done. In the air heat exchanger 9, the raw material air exchanges heat with the return oxygen gas, nitrogen gas or waste nitrogen gas from the low temperature part in the product oxygen gas line 27 or nitrogen / waste nitrogen gas line 28, and is cooled to near the liquefaction temperature. The
[0020]
The rectifying column 10 has a different configuration depending on the type of product to be collected (oxygen, nitrogen, argon, rare gas), pressure, purity, and properties (liquid state or gas state). FIG. 1 shows the simplest oxygen gas. And nitrogen gas sampling. In this invention, since the inside of the cold storage tank 5 is not prescribed | regulated, description is abbreviate | omitted.
[0021]
In the embodiment shown in FIG. 1, in the start-up process of the plant, in addition to the “cooling” step of cooling the cold storage tank 5 to the low operating temperature state (about −180 ° C.), the rectifying column 10 is provided. A “liquid storage” process is required to secure a large amount of liquefied oxygen (or liquefied air) as a predetermined liquid in the condenser 11 portion.
[0022]
The speed of the “cooling” process is determined by the balance between the cold generation capacity in the “cooling” process (for example, the cold generation capacity of the expansion turbine 8 and the liquid nitrogen supply capacity from the outside) and the allowable temperature drop rate of each part. . On the other hand, the speed of the “accumulation” and “purity setting” process after “cooling” is determined by the mass balance between the supply amount and the discharge amount with respect to the cold storage tank 5, and more raw material air is supplied to the cold storage tank 5. Becomes important.
[0023]
However, in the “accumulation” step of the main condenser 11, the amount of return gas (nitrogen gas or waste nitrogen gas) from the cold storage tank 5 is not sufficiently secured, so that drying for the adsorption tower 6 and evaporative cooling tower 4 is performed. Therefore, the adsorbing tower starting bypass valve 7 and the evaporative cooling tower starting bypass valve 3 are opened, and a part of the raw material air is supplied to the regeneration gas line 25 for regenerating the adsorption tower and the evaporative cooling tower gas line 23. The mass balance in this situation has the following relationships (1) to (3).
[0024]
CinMo2 = Yfo. (Fmc-Fevb-Fadb) (1)
Fwg = (Fmc-Fevb-Fadb) -Feo2 (2)
CoutMo2 = Yeo · (Feo2) + Yewg · (Fwg) (3)
Fmc is a raw material air compression amount (Nm3 / h) in the raw material air compressor 1 that is measured and input to the control computer 40. That is, Fmc is also the amount of compressed raw material air (Nm3 / h) supplied from the raw material air compressor 1. The compressed raw material air amount (Fmc) can be adjusted by automatically controlling the capacity control valve 32 based on a control command from the control computer 40.
Fevb is the air amount (Nm3 / h) of the evaporative cooling tower activation bypass 24 that is measured and input to the control computer 40.
Fadb is the air amount (Nm3 / h) of the adsorption tower activation bypass 26 that is measured and input to the control computer 40.
Yfo is an oxygen composition (% O 2 ) (usually about 21%) in the raw material air that is measured and input to the control computer 40.
CinMo2 is the amount of oxygen (Nm3 / h) supplied to the cold storage tank 5.
Feo2 is the amount of release (Nm3 / h) from the product oxygen line 27 that is measured and extracted from the cold storage tank 5 that is input to the control computer 40. The product oxygen release amount (Feo2) can be adjusted by automatically controlling the product release valve 29 based on a control command from the control computer 40.
Yeo is the oxygen composition (% O 2 ) in the same gas that is measured and input to the control computer 40 (usually about 80% for low purity and about 99.8% for high purity). Changes from initial value at startup to rated composition)
Fwg is the amount (Nm3 / h) of nitrogen gas (waste nitrogen) discharged from the cold storage tank 5 that is measured and input to the control computer 40. The release amount (Fwg) of this nitrogen gas (waste nitrogen) can be adjusted by automatically controlling the nitrogen release valve 30 based on a control command from the control computer 40.
Yewg is the oxygen composition (% O 2 ) in the same gas as measured and input to the control computer 40. (Normally about 10% to 20%.) (Change from initial value at startup to rated composition)
CoutMo2 is the amount of oxygen (Nm3 / h) discharged from the cold storage tank 5.
Cgain is the amount of oxygen (Nm3 / h) accumulated in the inside of the cold storage tank 5.
[0025]
Note that Fmc, Fevb, Fadb, Feo2, and Fwg may be calculated by the control computer 40 based on data obtained from each valve circuit.
[0026]
Therefore, the total amount of oxygen accumulated in the cold storage tank 5 at this time is expressed by the following equation (4).
[0027]
Cgain = CinMo2-CoutMo2 (4)
In order to shorten the time of the “accumulation” step, the result is how to take the oxygen component into the cold storage tank 5 in a short time, that is, how large Cgain is taken. However, in the start-up stage of the plant from “cooling” to “storage solution”, as described above, the raw material entering the cold storage tank 5 as the adsorption tower start bypass air amount (Fadb) and the evaporative cooling tower start bypass air amount (Fevb). This is the stage where the amount of air is reduced most, and the value of CinMo2 becomes low. On the other hand, in the “purity settling” step connected to “storage liquid”, a predetermined amount of oxygen purity is obtained, so that there is a tendency to extract a predetermined amount from the product oxygen gas line 27 in advance and to assure delivery as close to the rating as possible. is there. For this reason, in some cases, the value of Cgain becomes negative (the amount of accumulated oxygen is reversed), and instead of shortening the start-up time, the liquid oxygen amount and concentration of the main condenser 11 fall in a worsening direction, and the start-up is not successful. Sometimes possible.
[0028]
For the purpose of avoiding such problems and automatically shortening the startup time as much as possible, a control computer 40 such as a DCS (Distributed Control System) is provided to the cold storage tank 5 based on the above equation (1). Automatic measurement of the flow rate of the supply air (supply oxygen amount (CinMo2)), and the amount (Feo2) and purity (Yeo) of product oxygen released from the cold storage tank 5 at that time are automatically measured, and the above (2) The amount of waste gas (Yewg · (Fwg)) is calculated based on the equation, and at the same time, the amount of oxygen (CoutMo2) removed from the cold storage tank 5 is calculated internally based on the equation (3). Then, the oxygen accumulation amount (Cgain) in the inside of the cold storage tank 5 is calculated. The control computer 40 automatically performs the following control operation based on the obtained oxygen accumulation amount (Cgain).
(1) The control computer 40 measures the current liquid level value of the main condenser 11 to be measured when the oxygen accumulation amount (Cgain) in the cold storage tank 5 calculated one by one is greater than or equal to a predetermined value. From the purity (Yeo) of the product oxygen, a predicted completion time of “storage solution” and “purity settling” is calculated and displayed on the screen of the display device 41. If the completion prediction time is bad, the control computer 40 sets the capacity control valve 32 so as to increase the raw material air compression amount (Fmc) supplied from the raw material air compressor 1 based on the above equation (1). Control the control circuit including the above, or reduce the release amount (Feo2) of product oxygen extracted from the cold insulation tank 5 which is the main element of the oxygen amount (CoutMo2) discharged from the cold insulation tank 5 based on the above formula (3) Thus, the control circuit including the product discharge valve 29 is controlled. In addition, as long as the adsorption tower regeneration gas pressure permits, if the downstream conditions are satisfied (if the amount of nitrogen gas (waste nitrogen) discharged from the cold storage tank 5 can secure a necessary flow rate), the above equation (1) Based on the above, the "start bypass circuit" 26 or 24 controls the start bypass valve 7 or 3 in the closing direction to reduce the adsorption tower start bypass air amount (Fadb) or the evaporative cooling tower start bypass air amount (Fevb). It is also possible.
(2) When the oxygen accumulation amount (Cgain) in the cold storage tank 5 calculated one by one is equal to or less than a predetermined value, the control computer 40 is configured to perform the above operation until the oxygen accumulation amount (Cgain) recovers to the predetermined value ( The control circuit including the capacity control valve 32 is controlled so as to increase the raw material air compression amount (Fmc) supplied from the raw material air compressor 1 based on the formula 1), or the cold storage tank based on the formula (3) The control circuit including the product release valve 29 is controlled so as to reduce the release amount (Feo2) of the product oxygen extracted from the cold insulation tank 5 which is the main element of the oxygen amount (CoutMo2) discharged from 5.
[0029]
In addition, if the adsorption tower regeneration gas pressure permits and the downstream conditions are satisfied (if the necessary amount of nitrogen gas (waste nitrogen) discharged from the cold storage tank 5 can be secured), then “adsorption tower activation bypass” In the "circuit" 26, the starting bypass valve 7 is controlled in the closing direction, and in the "evaporative cooling tower starting bypass circuit" 24, similarly, the starting bypass valve 3 is controlled in the closing direction to adjust the adsorbing tower starting bypass air amount (Fadb) or It is also possible to reduce the amount of air (Fevb) in the evaporative cooling tower startup bypass.
[0030]
The control circuit and the bypass circuit are constituted by a flow rate control circuit.
(3) The control computer 40 judges from the value of the oxygen accumulation amount (Cgain) in the cold storage tank 5 calculated one by one, and is difficult to start up (the oxygen accumulation amount (Cgain) is 0 or less (negative)) In the case of the above, when the alarm operation is issued and the control operation (2) is executed, and the oxygen accumulation amount (Cgain) does not recover to 0 or more even after a certain time has elapsed (when correction cannot be made within a certain time). Outputs a message for urging the plant to stop (start-up request message) on the control computer using output means such as the display device 41.
[0031]
As described above, according to the embodiment of the present invention, the oxygen accumulation status in the cold storage tank in the startup process is sequentially and automatically monitored and calculated to determine whether the startup status is appropriate. As long as the situation of each part of the plant permits, by providing a function to automatically control the situation where oxygen is likely to accumulate, (1) Immediate detection / automatic correction of the inability to store liquid in the plant, (2) “Storage” Automatic control for shortening the time required for the “liquid” and “purity settling” process, (3) Even when the process is good, the completion time can be displayed from the calculated oxygen accumulation state.
[0032]
【The invention's effect】
According to the present invention, even if the activation is repeated frequently, there is an effect that it is possible to realize a chilled air separation device that automatically performs mass balance control and can shorten the activation time.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a cryogenic air separation device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Raw material air compressor, 2 ... Washing cooling tower, 3 ... Evaporative cooling tower starting bypass valve, 4 ... Evaporative cooling tower, 5 ... Cold box (cold storage tank), 6 ... Adsorption tower, 7 ... Adsorption tower starting bypass valve, DESCRIPTION OF SYMBOLS 8 ... Expansion turbine, 9 ... Air heat exchanger, 10 ... Rectification tower, 11 ... Main condenser, 12 ... Subcooler, 13 ... Regeneration gas heater, 14 ... Turbine line, 15 ... Cooling tank inlet line, 21 ... Cooling Water, 22 ... chiller water, 23 ... Gas line for evaporative cooling tower, 24 ... Evaporative cooling tower start bypass circuit, 25 ... Regeneration gas line, 26 ... Adsorption tower start bypass circuit, 27 ... Product oxygen gas line, 28 ... Nitrogen Waste nitrogen gas line, 29 ... product release valve, 30 ... nitrogen release valve, 31 ... valve, 32 ... capacity control valve, 40 ... control computer, 41 ... display device.

Claims (4)

原料空気圧縮機にて大気から圧縮され、吸着塔等にて前処理された空気を原料とし、深冷分離法にて原料の空気から窒素や酸素等を分離連続生産する保冷槽を有する深冷空気分離装置において、
前記原料空気圧縮機から供給される原料空気量または前記保冷槽から抽気される酸素量を制御する制御弁を含む制御回路と、
起動過程において、前記保冷槽の内部に酸素が蓄積される酸素蓄積状態を算出し、該算出された酸素蓄積状態を最適に保つように前記制御回路を制御する制御計算機とを備えたことを特徴とする深冷空気分離装置。Deep cooling with a cold storage tank that continuously produces nitrogen, oxygen, etc. separated from the raw material air by deep cooling using raw air compressed by the raw air compressor and pretreated by an adsorption tower In the air separation device,
A control circuit including a control valve for controlling the amount of raw material air supplied from the raw material air compressor or the amount of oxygen extracted from the cold storage tank;
A control computer for calculating an oxygen accumulation state in which oxygen is accumulated in the cold storage tank in a start-up process and controlling the control circuit so as to keep the calculated oxygen accumulation state optimal; Cryogenic air separation device. 原料空気圧縮機にて大気から圧縮され、吸着塔等にて前処理された空気を原料とし、深冷分離法にて原料の空気から窒素や酸素等を分離連続生産する保冷槽を有する深冷空気分離装置において、
前記吸着塔から前記保冷槽に供給される原料空気量を制御できるように前記吸着塔に入る原料空気または出る原料空気をバイパスさせるバイパス弁を含むバイパス回路と、
起動過程において、前記保冷槽の内部に酸素が蓄積される酸素蓄積状態を算出し、制御対象が許す限りにおいて、前記算出された酸素蓄積状態を最適に保つように前記バイパス回路のバイパス弁を閉じる方向に制御する制御計算機とを備えたことを特徴とする深冷空気分離装置。Deep cooling with a cold storage tank that continuously produces nitrogen, oxygen, etc. separated from the raw material air by deep cooling using raw air compressed by the raw air compressor and pretreated by an adsorption tower In the air separation device,
A bypass circuit including a bypass valve that bypasses the raw air that enters or exits the adsorption tower so that the amount of raw material air supplied from the adsorption tower to the cold storage tank can be controlled;
In the start-up process, an oxygen accumulation state in which oxygen is accumulated in the cold storage tank is calculated, and the bypass valve of the bypass circuit is closed so as to keep the calculated oxygen accumulation state optimal as long as the control object permits. A cryogenic air separation device comprising a control computer for controlling the direction. 請求項１または２記載の深冷空気分離装置において、前記制御計算機は、起動過程において算出された保冷槽への酸素蓄積状態から起動完了までの予想時間を算出し、該算出された起動完了までの予想時間を表示することを特徴とする深冷空気分離装置。3. The chilled air separation apparatus according to claim 1, wherein the control computer calculates an expected time from the oxygen accumulation state in the cold storage tank calculated in the startup process to the completion of startup until the calculated startup completion. A cryogenic air separator characterized by displaying the expected time of the air. 請求項１または２記載の深冷空気分離装置において、前記制御計算機は、起動過程において算出された保冷槽への酸素蓄積状態から判断して、起動が困難な状態で、しかも所望の時間内に是正できない場合には、起動中止要請のメッセージを出力することを特徴とする深冷空気分離装置。3. The chilled air separation device according to claim 1, wherein the control computer judges from the oxygen accumulation state in the cold storage tank calculated in the starting process and is difficult to start and within a desired time. When the correction cannot be made, the cryogenic air separation device outputs a message for requesting to stop the start-up.
JP2002172856A 2002-06-13 2002-06-13 Cryogenic air separation apparatus Pending JP2004019987A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101225380B1 (en) * 2005-12-23 2013-01-24 재단법인 포항산업과학연구원 A monitoring device for intercooler of a compressor and a control method thereof
WO2017112545A1 (en) * 2015-12-22 2017-06-29 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Systems and methods for automated startup of an air separation plant
CN110044134A (en) * 2019-03-29 2019-07-23 安徽加力气体有限公司 Full-automatic one key start stop control method of nitrogen making machine system
WO2020011396A1 (en) * 2018-07-13 2020-01-16 Linde Aktiengesellschaft Method for operating a heat exchanger, arrangement comprising a heat exchanger, and air processing system comprising a corresponding arrangement

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101225380B1 (en) * 2005-12-23 2013-01-24 재단법인 포항산업과학연구원 A monitoring device for intercooler of a compressor and a control method thereof
WO2017112545A1 (en) * 2015-12-22 2017-06-29 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude Systems and methods for automated startup of an air separation plant
WO2020011396A1 (en) * 2018-07-13 2020-01-16 Linde Aktiengesellschaft Method for operating a heat exchanger, arrangement comprising a heat exchanger, and air processing system comprising a corresponding arrangement
CN110044134A (en) * 2019-03-29 2019-07-23 安徽加力气体有限公司 Full-automatic one key start stop control method of nitrogen making machine system

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