JP4230168B2 - Nitrogen production method and apparatus - Google Patents

Nitrogen production method and apparatus Download PDF

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JP4230168B2
JP4230168B2 JP2002134502A JP2002134502A JP4230168B2 JP 4230168 B2 JP4230168 B2 JP 4230168B2 JP 2002134502 A JP2002134502 A JP 2002134502A JP 2002134502 A JP2002134502 A JP 2002134502A JP 4230168 B2 JP4230168 B2 JP 4230168B2
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air
nitrogen gas
liquefied
pressure rectification
nitrogen
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JP2003329364A (en
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真 入澤
俊幸 野島
高司 辰巳
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Taiyo Nippon Sanso Corp
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    • 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
    • F25J3/04254—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using the cold stored in external cryogenic fluids
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    • 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
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    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
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    • F25J3/04436—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 at least a triple pressure main column system
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    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
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    • F25J3/04763—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
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
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    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/0489—Modularity and arrangement of parts of the air fractionation unit, in particular of the cold box, e.g. pre-fabrication, assembling and erection, dimensions, horizontal layout "plot"
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    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04969—Retrofitting or revamping of an existing air fractionation unit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/34—Processes or apparatus using separation by rectification using a side column fed by a stream from the low pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/52—Processes or apparatus involving steps for increasing the pressure of gaseous process streams the fluid being oxygen enriched compared to air, e.g. "crude oxygen"
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    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream

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  • Mechanical Engineering (AREA)
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Description

【０００１】
【発明の属する技術分野】
本発明は、窒素製造方法及び装置に関し、特に、製品窒素ガス消費量の広範囲な増減に対応でき、さらに、異なる純度や圧力の製品窒素ガスの供給にも対応可能な窒素製造方法及び装置に関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
図４は、需要変動に対応するために考案された従来の循環型窒素製造装置の一例を示す系統図である。また、表１及び表２は、この窒素製造装置のプロセス計算の一例を示すもので、表１は定格運転時のプロセス値を、表２は最大減量運転時のプロセス値をそれぞれ示している。なお、表１、表２中のＡ〜Ｊは、図４におけるＡ点〜Ｊ点を表している。
【０００３】
以下、本装置における気液の流れに沿って従来の循環型窒素製造プロセスを簡単に説明する。まず、大気から取入れられて空気圧縮機１で圧縮された圧縮空気は、精製設備２で精製された後、排ガス圧縮機３で圧縮された排ガスと合流して原料空気となり、主熱交換器４で戻りガス（製品ガス、排ガス）と熱交換して冷却される。
【０００４】
冷却後の原料空気は、中圧精留塔５に導入され、塔頂部の窒素ガスと塔底部の液化空気とに液化精留分離される。液化空気は、塔底部から管路６に抜き出され、減圧弁７で減圧された後、低圧精留塔８の上部に導入され、大気の酸素濃度に近い塔頂部の擬似空気と、液化空気よりも酸素濃度の高い塔底部の酸素富化空気とに分離される。
【０００５】
擬似空気は、排ガスとして塔頂部から管路９に抜き出され、主熱交換器４で加温された後、前記排ガス圧縮機３で圧縮されて圧縮空気と合流する。また、塔下部のガス状の酸素富化空気は、管路１０に抜き出され、その一部が管路１１を通って主熱交換器４で中間温度まで加温された後、膨張タービン１２に導入されて断熱膨張し、装置の運転に必要な寒冷を発生させる。寒冷を発生した酸素富化空気は、再び主熱交換器４に導入されて原料空気と熱交換を行い、加温されて系外に排出される。
【０００６】
このような循環型プロセスは、二つの特徴を有している。その一つは、余剰の排ガスを原料空気として再利用することで製品収率を高くしている点である。もう一つは、再利用する排ガスの酸素濃度を大気組成に近い濃度まで低下させることにより、排ガス圧縮機３を高価な酸素圧縮機仕様とする必要をなくし、設備費を低減している点である。
【０００７】
次に、このプロセスにおける減量運転を考える。一般に精留塔は、ある処理量の範囲内で効率を低下させることなく運転できる。そこで、ここでの検討においては、一般的な精留塔の設計を考え、中圧精留塔５の運転範囲は、導入される原料空気の量で１００〜６０％の範囲で同一の効率を備えるとする。また、定格運転時の各部のプロセス値を表１に示す通りとする。
【０００８】
従来の循環型プロセスで減量運転を行う場合は、まず、排ガス圧縮機３を停止させる。これにより、原料空気中の排ガス量が０になるので、圧縮空気量を定格運転の１００のままとしても、原料空気量は１３８から１００に減少して７２％の減量となる。そして、表２に示すように圧縮空気量を８３に減量すると、原料空気量は定格運転時の１３８から８３に減少し、６０％の減量となる。したがって、圧縮空気量が８３のとき、中圧精留塔５は運転範囲の下限になる。このとき、管路１３から採取する製品窒素ガス量は、定格運転に比べて５９％の減量となる。
【０００９】
【表１】

Figure 0004230168
【００１０】
【表２】
Figure 0004230168
【００１１】
このように、循環型プロセスは、減量運転において圧縮空気の減少量以上に精留塔に導入する原料空気量が減少する。したがって、圧縮空気の減量幅（空気圧縮機の減量幅）に余裕があっても、精留塔の減量下限界が先に到達し、その結果、製品の減量幅が制限される場合があった。すなわち、従来の方法では、精留塔における負荷変動幅が大きくなり、精留塔の操作限界によって減量幅が制限されるという問題があった。
【００１２】
また、窒素ガスを様々な用途に使用する半導体製造工場等では、純度や圧力等の仕様が異なる窒素ガスの供給を要望されることがある。この場合、異なる純度の窒素ガスを製造するための複数の窒素製造装置を設置してそれぞれ供給することも可能であるが、装置コストが多大なものとなるため、例えば、高純度窒素ガスを製造する装置のみを設置し、比較的低純度の窒素ガスで十分な用途にも高価な高純度窒素ガスを使用したり、別途液化窒素貯槽を設置してここから所望純度の窒素ガスを供給するようにしており、ガスコストや設備コストに問題があった。
【００１３】
そこで本発明は、従来と同程度の動力原単位でより広範囲な製品窒素ガス使用量の増減に対応でき、必要に応じて純度や圧力の異なる製品を供給することも可能な窒素製造方法及び装置を提供することを目的としている。
【００１４】
【課題を解決するための手段】
上記目的を達成するため、本発明の窒素製造方法は、第１の構成として、圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造方法において、圧縮、精製、冷却した原料空気を第一窒素ガスと第一液化空気とに分離して第一窒素ガスの一部を加温してから第一製品窒素ガスとして採取する第一中圧精留工程と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留工程と、低圧精留工程で得た液状の酸素富化空気と第一窒素ガスとを熱交換させて第一窒素ガスを液化すると同時に酸素富化空気を気化し、液化した第一窒素ガスを第一中圧精留工程の還流液とする第一窒素ガス液化工程と、低圧精留工程で得た擬似空気を加温してから圧縮する擬似空気圧縮工程と、擬似空気圧縮工程で圧縮後に冷却した擬似空気を第二窒素ガスと第二液化空気とに分離して第二窒素ガスの一部を加温してから第二製品窒素ガスとして採取する第二中圧精留工程と、第二中圧精留工程で得た第二窒素ガスと第二液化空気とを熱交換させて第二窒素ガスを液化すると同時に第二液化空気を気化し、液化した第二窒素ガスを第二中圧精留工程の還流液とし、気化した第二液化空気を加温してから排出する第二窒素ガス液化工程と、低圧精留工程で得た液状の酸素富化空気の一部を第二液化空気に注入する液注入工程とを含むことを特徴としている。
【００１５】
本発明方法の第２の構成は、圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造方法において、圧縮、精製、冷却した原料空気を第一窒素ガスと第一液化空気とに分離して第一窒素ガスの一部を原料空気で加温してから第一製品窒素ガスとして採取する第一中圧精留工程と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留工程と、低圧精留工程で得た液状の酸素富化空気と第一窒素ガスとを熱交換させて第一窒素ガスを液化すると同時に酸素富化空気を気化し、液化した第一窒素ガスを第一中圧精留工程の還流液とする第一窒素ガス液化工程と、低圧精留工程で得た擬似空気を原料空気で加温してから圧縮する擬似空気圧縮工程と、擬似空気圧縮工程で圧縮後に冷却した擬似空気を第二窒素ガスと第二液化空気とに分離して第二窒素ガスの一部を圧縮後の擬似空気で加温してから第二製品窒素ガスとして採取する第二中圧精留工程と、第二中圧精留工程で得た第二窒素ガスと第二液化空気とを熱交換させて第二窒素ガスを液化すると同時に第二液化空気を気化し、液化した第二窒素ガスを第二中圧精留工程の還流液とし、気化した第二液化空気を圧縮後の擬似空気で加温してから排出する第二窒素ガス液化工程と、低圧精留工程で得た液状の酸素富化空気の一部を第二液化空気に注入する液注入工程とを含むことを特徴としている。
【００１６】
さらに、本発明の窒素製造方法は、該窒素製造方法を実施する運転に必要な寒冷を、断熱膨張により得る工程又は前記運転に必要な寒冷を外部からの低温液化ガスのプロセス流体への注入により得る工程を含むことを特徴としている。また、前記第一製品窒素ガスの純度と前記第二製品窒素ガスの純度とが異なるようにすることもでき、前記第一製品窒素ガスの圧力と前記第二製品窒素ガスの圧力とが異なるようにすることもできる。
【００１７】
本発明の窒素製造装置は、第１の構成として、圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造装置において、原料空気を圧縮する圧縮機と、圧縮された原料空気を精製する精製設備と、精製された原料空気を冷却する主熱交換器と、冷却された原料空気を第一窒素ガスと第一液化空気とに分離する第一中圧精留塔と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留塔と、第一中圧精留塔の精留に必要な精留塔還流液及び低圧精留塔の精留に必要な精留塔上昇ガスを生成するために第一窒素ガスと液状の酸素富化空気とを熱交換させて第一窒素ガスを液化すると同時に液状の酸素富化空気をガス化する第一凝縮器と、擬似空気を常温で圧縮する擬似空気圧縮機と、圧縮後に主熱交換器で冷却した擬似空気を第二窒素ガスと第二液化空気とに分離する第二中圧精留塔と、第二中圧精留塔の精留に必要な精留塔還流液を生成するために第二窒素ガスと第二液化空気とを間接熱交換させて第二窒素ガスを液化すると同時に第二液化空気をガス化する第二凝縮器と、低圧精留塔の下部から酸素富化空気の一部をガス状で導出して主熱交換器で加温してから導出する管路と、第一中圧精留塔の上部から導出した第一窒素ガスを主熱交換器で加温してから第一製品窒素ガスとして採取する管路と、第一中圧精留塔の下部から導出した第一液化空気を減圧後に低圧精留塔の上部に導入する管路と、低圧精留塔の上部から導出した擬似空気を主熱交換器で加温してから擬似空気圧縮機に導入する管路と、圧縮後の擬似空気を主熱交換器で冷却してから第二中圧精留塔に導入する管路と、第二中圧精留塔の上部から導出した第二窒素ガスを主熱交換器で加温してから第二製品窒素ガスとして採取する管路と、低圧精留塔の下部から液状で導出した酸素富化空気と第二中圧精留塔の下部から導出した第二液化空気とを合流させて第二凝縮器に導入する管路と、第二凝縮器でガス化した第二液化空気を主熱交換器で加温してから導出する管路とを備えていることを特徴としている。
【００１８】
また、本発明の窒素製造装置における第２の構成は、圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造装置において、原料空気を圧縮する圧縮機と、圧縮された原料空気を精製する精製設備と、精製された原料空気を冷却する主熱交換器と、冷却された原料空気を第一窒素ガスと第一液化空気とに分離する第一中圧精留塔と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留塔と、第一中圧精留塔の精留に必要な精留塔還流液及び低圧精留塔の精留に必要な精留塔上昇ガスを生成するために第一窒素ガスと液状の酸素富化空気とを熱交換させて第一窒素ガスを液化すると同時に液状の酸素富化空気をガス化する第一凝縮器と、擬似空気を常温で圧縮する擬似空気圧縮機と、圧縮後の擬似空気を冷却する第二主熱交換器と、第二主熱交換器で冷却された擬似空気を第二窒素ガスと第二液化空気とに分離する第二中圧精留塔と、第二中圧精留塔の精留に必要な精留塔還流液を生成するために第二窒素ガスと第二液化空気とを熱交換させて第二窒素ガスを液化すると同時に第二液化空気をガス化する第二凝縮器と、第一凝縮器でガス化した酸素富化空気の一部を低圧精留塔の下部からガス状で導出して主熱交換器で加温してから導出する管路と、第一中圧精留塔の上部から導出した第一窒素ガスを主熱交換器で加温してから第一製品窒素ガスとして採取する管路と、第一中圧精留塔の下部から導出した第一液化空気を減圧後に低圧精留塔の上部に導入する管路と、低圧精留塔の上部から導出した擬似空気を主熱交換器で加温してから擬似空気圧縮機に導入する管路と、圧縮後の擬似空気を第二主熱交換器で冷却してから第二中圧精留塔に導入する管路と、第二中圧精留塔の上部から導出した第二窒素ガスを第二主熱交換器で加温してから第二製品窒素ガスとして採取する管路と、低圧精留塔の下部から液状で導出した酸素富化空気と第二中圧精留塔の下部から導出した第二液化空気とを合流させて第二凝縮器に導入する管路と、第二凝縮器でガス化した第二液化空気を第二主熱交換器で加温してから導出する管路とを備えていることを特徴としている。
【００１９】
さらに、本発明の窒素製造装置は、前記窒素製造装置の運転に必要な寒冷を発生させる膨張タービン又は前記窒素製造装置の運転に必要な寒冷を供給するための低温液化ガスをプロセス流体へ注入する管路を備えていることを特徴としている。また、前記液化した第一窒素ガス又は第二窒素ガスを製品液化窒素として導出する管路を備えていること、前記第一中圧精留塔と第二中圧精留塔とが一つの保冷外槽に格納されていること、あるいは、前記第一中圧精留塔と第二中圧精留塔とが異なる保冷外槽に格納されていることを特徴としている。
【００２０】
なお、製品窒素ガスを供給する場合、両製品窒素ガスの純度や圧力が同じならば、各導出管路を一つの製品ガス導出管路に合流させればよい。このとき、合流前の両製品窒素ガスの圧力が異なる場合は、圧力が高い方の製品窒素ガス導出管路に減圧弁を設ければよい。また、純度が異なる製品窒素ガスを採取するには、前記第一中圧精留塔と第二中圧精留塔の理論段数を異なるものとしたり、原料空気や擬似空気に対する窒素ガス採取量を異なるものとしたりすることによって行うことができる。
【００２１】
【発明の実施の形態】
図１は、本発明の窒素製造方法を適用した窒素製造装置の第１形態例を示す系統図である。この窒素製造装置は、主要な機器として、原料空気を冷却する主熱交換器２１と、冷却された原料空気を第一窒素ガスと第一液化空気とに分離する第一中圧精留塔２２と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留塔２３と、擬似空気を常温で圧縮する擬似空気圧縮機２４と、圧縮後に冷却した擬似空気を第二窒素ガスと第二液化空気とに分離する第二中圧精留塔２５とを備えている。なお、各機器は、従来から用いられているこの種の機器をそのまま使用することが可能である。
【００２２】
まず、圧縮機３１であらかじめ設定された圧力、例えば０．９ＭＰａに圧縮された原料空気は、精製設備３２において、例えばＭＳ吸着器で水、二酸化炭素等の高沸点不純物を除去された後、例えば０．８６ＭＰａとなって主熱交換器２１に導入され、低温の各種戻りガスと間接熱交換を行ってあらかじめ設定された温度、例えば−１６７℃に冷却される。
【００２３】
冷却後の原料空気は、管路５１を通って第一中圧精留塔２２の下部に導入され、該第一中圧精留塔２２での第一中圧精留工程により、塔頂部の第一窒素ガスと塔底部の第一液化空気とに分離する。塔頂部の第一窒素ガスは、管路５２に抜き出され、その一部が管路５３に分岐して主熱交換器２１に導入され、原料空気等と間接熱交換することによって常温に加温された後、管路５４から０．８２ＭＰａで第一製品窒素ガスＮ１として採取される。
【００２４】
塔底部の第一液化空気は、管路５５に抜き出され、減圧弁３３であらかじめ設定された圧力、例えば０．３０ＭＰａに減圧された後、低圧精留塔２３の上部に導入され、該低圧精留塔２３での低圧精留工程により、大気に近い酸素濃度の塔頂部の擬似空気と、第一液化空気よりも酸素濃度の高い塔底部の液状の酸素富化空気とに分離する。
【００２５】
低圧精留塔２３の底部には、第一窒素ガス液化工程を行う第一凝縮器３４が設けられており、この第一凝縮器３４において、前記管路５２から管路５６に分岐した第一窒素ガスと塔底部の液状の酸素富化空気とが間接熱交換を行い、第一窒素ガスが液化すると同時に酸素富化空気が気化する。液化した第一窒素ガス（第一液化窒素）は、管路５７を通って第一中圧精留塔２２の頂部に導入されて還流液となり、気化した酸素富化空気は、低圧精留塔２３の上昇ガスとなる。
【００２６】
また、低圧精留塔２３内を上昇するガス状の酸素富化空気の一部は、管路５８に抜き出され、その一部が管路５９を経て主熱交換器２１に導入される。主熱交換器２１で中間温度まで加温された酸素富化空気は、膨張タービン３５に導入され、例えば０．１３ＭＰａまで断熱膨張し、装置の運転に必要な寒冷を発生させる。この寒冷発生工程を終えた酸素富化空気は、管路５８から弁３６を介して分岐した酸素富化空気と管路６０で合流し、主熱交換器２１を通って原料空気等の冷却源となって常温まで加温された後、管路６１から排ガスＷとして排出される。なお、この排ガスの一部は、精製設備３２の再生ガスとして使用される。
【００２７】
低圧精留塔２３の頂部から管路６２に抜き出された擬似空気は、主熱交換器２１で常温に加温された後、定格運転時にはその全量が擬似空気圧縮機２４での擬似空気圧縮工程により、あらかじめ設定された圧力、例えば０．８６ＭＰａに圧縮される。圧縮後の擬似空気は、管路６３から再び主熱交換器２１に導入されて−１６７℃に冷却され、管路６４を通って第二中圧精留塔２５の下部に導入される。
【００２８】
第二中圧精留塔２５での第二中圧精留工程により、擬似空気は、塔頂部の第二窒素ガスと塔底部の第二液化空気とに分離する。塔頂部の第二窒素ガスは、管路６５に抜き出され、その一部が管路６６に分岐して主熱交換器２１に導入され、原料空気等と間接熱交換することによって常温に加温された後、管路６７から０．８２ＭＰａの第二製品窒素ガスＮ２として採取される。
【００２９】
塔底部の第二液化空気は、管路６８に抜き出され、減圧弁３７であらかじめ設定された圧力、例えば０．１３ＭＰａに減圧された後、第二窒素ガス液化工程を行う第二凝縮器３８に導入される。また、第二液化空気には、液注入工程により、低圧精留塔２３の底部から管路６９に抜き出された液状の酸素富化空気が、減圧弁３９で第二液化空気と同じ圧力に減圧された後に注入されている。
【００３０】
この第二凝縮器３８には、管路６５から管路７０に分岐した第二窒素ガスが導入されており、この第二窒素ガスと第二液化空気とが間接熱交換を行い、第二窒素ガスが液化すると同時に第二液化空気が気化する。液化した第二窒素ガス（第二液化窒素）は、管路７１を通って第二中圧精留塔２５の頂部に導入されて還流液となり、気化した第二液化空気は、管路７２を通り、膨張タービン３５を出た酸素富化空気に合流して排出される。
【００３１】
このように形成した窒素製造装置で大幅な減量運転を行う際には、擬似空気圧縮機２４を停止させて第二中圧精留塔２５の運転を停止して擬似空気を弁４０から排出するとともに、管路６９からの液状の酸素富化空気の注入も停止し、第一中圧精留塔２２のみによって製品窒素ガスを製造する運転を行う。これにより、製品窒素ガスの採取量は第二中圧精留塔２５からの第二製品窒素ガスＮ２に相当する分が減量される。さらに、第一中圧精留塔２２の運転範囲が従来と同様の１００〜６０％だとすれば、第一中圧精留塔２２から採取する第一製品窒素ガスの採取量を定格運転時の６０％まで減量できることになる。したがって、擬似空気圧縮機２４の停止と、第一中圧精留塔２２の減量運転とにより、製品窒素ガスの採取量を、定格運転時の４３％にまで減量することが可能となる。
【００３２】
この窒素製造装置で定格運転時の原料空気量を１００としたときのプロセス値の一例を表３に示す。さらに、最大減量運転時のプロセス値の一例を表４に示す。なお、表３、表４中のＡ〜Ｏは、図１におけるＡ点〜Ｏ点を表している。また、従来の循環型窒素製造プロセスと、本形態例に示す窒素製造プロセスとにおける減量幅と圧縮機理論動力とを比較した結果を表５に示す。なお、表５において、ガス圧縮機は、従来例における排ガス圧縮機３及び本形態例における擬似空気圧縮機２４を示している。
【００３３】
【表３】
Figure 0004230168
【００３４】
【表４】
Figure 0004230168
【００３５】
【表５】
Figure 0004230168
【００３６】
さらに、製品窒素ガスの採取、供給を第一中圧精留塔２２及び第二中圧精留塔２５の二塔で行い、第二中圧精留塔２５は、擬似空気圧縮機２４で圧縮後の擬似空気を使用しているので、原料空気のみを使用した第一中圧精留塔２２の運転とは関係なく、二塔それぞれの運転を独立して行うことができる。
【００３７】
したがって、同一純度及び同一圧力の製品窒素ガスをそれぞれ採取することによって前述のような大幅な需要変動に対応することが可能となるが、一方で、両塔における運転条件や、両塔における理論段数の設定によっては、各塔から純度や圧力の異なる製品窒素ガスをそれぞれ採取することができる。すなわち、一方の中圧精留塔から高純度の製品窒素ガスを採取し、他方の中圧精留塔から汎用純度の製品窒素ガスを採取するような設定も可能である。
【００３８】
また、両製品窒素ガスの採取圧力を同じにすることよって第一、第二製品窒素ガスの合流を容易に行うことができ、一つの製品ガス導出管路に合流させて供給することができるが、擬似空気圧縮機２４での圧縮圧力を適宜に設定することにより、第二製品窒素ガスの圧力を第一製品窒素ガスの圧力と異なる圧力に設定することができる。なお、採取圧力が異なる両製品窒素ガスを合流させる場合は、圧力の高い製品窒素ガスの管路に減圧弁を設けて同じ圧力にすればよい。
【００３９】
さらに、発生寒冷量や運転条件の設定により、各凝縮器で液化して各中圧精留塔に還流液としてそれぞれ導入される第一、第二液化窒素の一部を、精留塔導入前又は導入後に必要に応じて抜き取り、製品液化窒素として採取することもできる。
【００４０】
図２は、本発明の第２形態例を示す系統図である。なお、以下の説明において、前記第１形態例に示した窒素製造装置と同一の構成要素には同一の符号を付して詳細な説明は省略する。
【００４１】
本形態例に示す窒素製造装置は、主熱交換器として、第一中圧精留塔２２及び低圧精留塔２３に関連する第一主熱交換器２１と、第二中圧精留塔２５に関連する第二主熱交換器２６とを設けている。すなわち、第二中圧精留塔２５に導入される擬似空気圧縮機２４で圧縮後の擬似空気の管路６３、第二中圧精留塔２５で分離した第二窒素ガスを第二製品窒素ガスＮ２として採取する管路６７、第二凝縮器３８で気化して排出される気化した第二液化空気の管路７２を第二主熱交換器２６に設けるようにしている。
【００４２】
さらに、前記第１形態例では、全ての低温機器を一つの保冷外槽８１に収納しているが、本形態例では、第一中圧精留塔２２や低圧精留塔２３、第一主熱交換器２１に関連する低温機器と、第二中圧精留塔２５や第二主熱交換器２６に関連する低温機器とを異なる保冷外槽８２，８３にそれぞれ収納し、両保冷外槽間にまたがる管路６９を断熱配管で形成して接続するようにしている。
【００４３】
このように保冷外槽を別に形成することにより、例えば、工場建設の初期で供給先の製品窒素ガスの需要量が比較的少ない場合には、第二中圧精留塔２５側の機器や保冷外槽８３を設置せずに、第一中圧精留塔２２側の設備のみを設置してここから製品窒素ガスを採取するように形成し、製品窒素ガスの需要量が増大したときに、第二中圧精留塔２５に関連する設備及び保冷外槽８３を追加して両中圧精留塔から製品窒素ガスを採取するように形成することにより、初期投資額の削減が可能となる。
【００４４】
図３は、本発明の第３形態例を示す系統図である。本形態例に示す窒素製造装置は、装置の運転に必要な寒冷を、前記両形態例に示した膨張タービンでの断熱膨張で得るのに代えて、外部からの低温液化ガスの注入により得るようにした例を示している。
【００４５】
すなわち、前記低圧精留塔２３から管路５８に抜き出したガス状の酸素富化空気は、その全量を弁３６から管路６０を通して主熱交換器２１に導入するように形成するとともに、外部から低温液化ガスを装置内に注入するための管路１００を設け、該管路１００から、低温液化ガスの種類や組成、圧力に応じて装置内の適当な箇所に低温液化ガスを注入することにより、寒冷を供給するようにしている。
【００４６】
例えば、外部から注入する低温液化ガスとして、製品窒素ガスの純度に相当する純度を有し、第一中圧精留塔２２の運転圧力に相当する圧力を有する液化窒素の場合は、前記管路１００から管路１０１を介して第一中圧精留塔２２に注入することができる。同様に、第二中圧精留塔２５に注入することも可能であり、さらに、精留塔に直接ではなく、管路５７を流れる第一液化窒素や、管路７１を流れる第二液化窒素に合流させることもできる。このようにして第一、第二中圧精留塔に注入された液化窒素は、寒冷供給用として利用された後、製品窒素ガスの一部として採取することができる。
【００４７】
また、低純度の液化窒素や液化空気の場合、あるいは、ある程度の純度を有していても圧力が低い液化窒素の場合は、前記管路１００から弁１０２、管路１０３を介して管路５５を流れる減圧後の第一液化空気に合流させたり、該管路１００から管路１０４、弁１０５を介して管路６８の第二液化空気に合流させたりすることができる、さらに、これらの注入箇所を適当に組み合わせることもできる。また、低温液化ガス注入用の管路は、膨張タービンを設置した装置に併設することもでき、例えば、膨張タービンのメンテナンス中に使用したり、両者の寒冷を併用するようにしてもよい。
【００４８】
加えて、前記第２形態例に示したように、保冷外槽を分割した場合は、第一中圧精留塔２２側の運転に必要な寒冷を前記膨張タービン３５で発生させるようにし、第二中圧精留塔２５側の運転に必要な寒冷を外部からの低温液化ガスの注入によって得るように設定することもできる。この場合、寒冷補給用としての管路６９を省略できるので、両保冷外槽にまたがる低温配管を設ける必要がなくなり、熱損失の低減や設備コストの削減を図れる。
【００４９】
【発明の効果】
以上説明したように、本発明によれば、従来から用いられている機器をそのまま使用しながら、原単位を悪化させることなく製品窒素ガスの採取量を大幅に変動させることができる。また、必要に応じて異なる圧力、異なる純度の製品窒素ガスを採取することも可能である。
【図面の簡単な説明】
【図１】 本発明の窒素製造方法を適用した窒素製造装置の第１形態例を示す系統図である。
【図２】 本発明の窒素製造装置の第２形態例を示す系統図である。
【図３】 本発明の窒素製造装置の第３形態例を示す系統図である。
【図４】 従来の循環型窒素製造装置の一例を示す系統図である。
【符号の説明】
２１…主熱交換器、２２…第一中圧精留塔、２３…低圧精留塔、２４…擬似空気圧縮機、２５…第二中圧精留塔、２６…第二主熱交換器、３１…圧縮機、３２…精製設備、３４…第一凝縮器、３５…膨張タービン、３８…第二凝縮器、８１，８２，８３…保冷外槽、１００，１０１，１０３，１０４…低温液化ガス注入用の管路、Ｎ１…第一製品窒素ガス、Ｎ２…第二製品窒素ガス、Ｗ…排ガス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nitrogen production method and apparatus, and more particularly, to a nitrogen production method and apparatus that can cope with a wide range of increase and decrease in product nitrogen gas consumption and can also supply product nitrogen gas of different purity and pressure.
[0002]
[Prior art and problems to be solved by the invention]
FIG. 4 is a system diagram showing an example of a conventional circulating nitrogen production apparatus devised to cope with demand fluctuations. Tables 1 and 2 show an example of the process calculation of the nitrogen production apparatus. Table 1 shows the process value at the rated operation, and Table 2 shows the process value at the maximum weight reduction operation. A to J in Tables 1 and 2 represent points A to J in FIG.
[0003]
Hereinafter, a conventional circulating nitrogen production process will be briefly described along the flow of gas and liquid in this apparatus. First, the compressed air taken in from the atmosphere and compressed by the air compressor 1 is purified by the refining equipment 2 and then merged with the exhaust gas compressed by the exhaust gas compressor 3 to become raw air, and the main heat exchanger 4 The product is cooled by exchanging heat with the return gas (product gas, exhaust gas).
[0004]
The raw material air after cooling is introduced into the intermediate pressure rectification column 5 and liquefied and rectified and separated into nitrogen gas at the top of the column and liquefied air at the bottom of the column. The liquefied air is extracted from the bottom of the tower to the pipe line 6 and decompressed by the pressure reducing valve 7 and then introduced into the upper part of the low pressure rectifying tower 8, and the pseudo air at the top of the tower close to the atmospheric oxygen concentration and the liquefied air Is separated into oxygen-enriched air at the bottom of the column having a higher oxygen concentration.
[0005]
The simulated air is extracted as exhaust gas from the top of the tower to the pipe 9, heated by the main heat exchanger 4, compressed by the exhaust gas compressor 3, and merged with the compressed air. Further, the gaseous oxygen-enriched air at the bottom of the tower is extracted to the pipe 10, and a part thereof is heated to the intermediate temperature by the main heat exchanger 4 through the pipe 11, and then the expansion turbine 12. It is introduced into the adiabatic and expands adiabatically, generating the cold necessary for the operation of the apparatus. The oxygen-enriched air that has generated cold is again introduced into the main heat exchanger 4 to exchange heat with the raw material air, and is heated and discharged out of the system.
[0006]
Such a cyclic process has two characteristics. One of them is that the product yield is increased by reusing excess exhaust gas as raw material air. The other is that by reducing the oxygen concentration of the exhaust gas to be reused to a concentration close to the atmospheric composition, it is not necessary to make the exhaust gas compressor 3 an expensive oxygen compressor specification, thereby reducing the equipment cost. is there.
[0007]
Next, consider the weight loss operation in this process. Generally, the rectification column can be operated within a certain throughput without reducing the efficiency. Therefore, in the examination here, considering the design of a general rectification column, the operation range of the intermediate pressure rectification column 5 has the same efficiency in the range of 100 to 60% in terms of the amount of raw material air introduced. Let's prepare. Table 1 shows the process value of each part during rated operation.
[0008]
When performing a weight reduction operation in a conventional circulation type process, first, the exhaust gas compressor 3 is stopped. Thereby, since the amount of exhaust gas in the raw material air becomes 0, even if the amount of compressed air remains at 100 of the rated operation, the amount of raw material air decreases from 138 to 100, which is a 72% reduction. As shown in Table 2, when the amount of compressed air is reduced to 83, the amount of raw material air is reduced from 138 during rated operation to 83, which is a reduction of 60%. Therefore, when the amount of compressed air is 83, the intermediate pressure rectification column 5 becomes the lower limit of the operating range. At this time, the amount of product nitrogen gas collected from the pipeline 13 is reduced by 59% compared to the rated operation.
[0009]
[Table 1]
Figure 0004230168
[0010]
[Table 2]
Figure 0004230168
[0011]
Thus, in the circulation type process, the amount of raw material air introduced into the rectification column is reduced more than the amount of reduction in compressed air in the reduction operation. Therefore, even if there is a margin for the amount of compressed air reduction (the amount of air compressor reduction), the lower limit of rectifying column weight loss reached first, and as a result, the product weight reduction range was sometimes limited. . In other words, the conventional method has a problem that the load fluctuation range in the rectification column becomes large, and the amount of weight reduction is limited by the operation limit of the rectification column.
[0012]
In addition, in semiconductor manufacturing factories or the like that use nitrogen gas for various purposes, it may be desired to supply nitrogen gas having different specifications such as purity and pressure. In this case, it is possible to install and supply a plurality of nitrogen production apparatuses for producing nitrogen gases of different purity. However, since the apparatus cost becomes enormous, for example, high purity nitrogen gas is produced. Only high-pure nitrogen gas can be used for applications where relatively low-purity nitrogen gas is sufficient, or a separate liquefied nitrogen storage tank is installed to supply nitrogen gas of the desired purity from there. There was a problem in gas cost and equipment cost.
[0013]
Accordingly, the present invention provides a method and apparatus for producing nitrogen capable of responding to a wide range of product nitrogen gas consumption fluctuations with a power unit comparable to that of the prior art and capable of supplying products of different purity and pressure as required. The purpose is to provide.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the nitrogen production method of the present invention has, as a first configuration, a nitrogen production method in which nitrogen is separated by low-temperature liquefaction rectification of compressed, purified, and cooled raw material air. A first intermediate pressure rectification step in which the cooled raw material air is separated into first nitrogen gas and first liquefied air, and a part of the first nitrogen gas is heated and then collected as the first product nitrogen gas; Low-pressure rectification process that separates liquefied air into simulated air with oxygen concentration close to the atmosphere and oxygen-enriched air with higher oxygen concentration than the first liquefied air, and liquid oxygen-enriched air obtained in the low-pressure rectification process The first nitrogen gas is liquefied by simultaneously exchanging heat with the first nitrogen gas, and at the same time, oxygen-enriched air is vaporized, and the liquefied first nitrogen gas is used as a reflux liquid in the first intermediate pressure rectification step. The simulated air obtained in the liquefaction process and the low-pressure rectification process is heated and then compressed. The second product nitrogen gas after the pseudo air compression process and the pseudo air cooled after the compression in the pseudo air compression process are separated into the second nitrogen gas and the second liquefied air, and a part of the second nitrogen gas is heated. The second intermediate pressure rectification step collected as the second intermediate pressure rectification step and the second nitrogen gas obtained in the second intermediate pressure rectification step are heat exchanged with the second liquefied air to liquefy the second nitrogen gas and at the same time the second liquefied air Vaporized and liquefied second nitrogen gas is used as the reflux liquid in the second intermediate pressure rectification process, and the second liquefied air that has been vaporized is heated and then discharged, and obtained in the low pressure rectification process. And a liquid injection step of injecting a part of the liquid oxygen-enriched air into the second liquefied air.
[0015]
A second configuration of the method of the present invention is a method for producing nitrogen in which nitrogen is separated by low-temperature liquefaction rectification of compressed, refined, and cooled raw material air. A first intermediate pressure rectification process in which a part of the first nitrogen gas is heated to the raw material air after being separated into one liquefied air and then collected as the first product nitrogen gas, and the first liquefied air is oxygen close to the atmosphere. The low-pressure rectification process that separates the concentration of pseudo air and the oxygen-enriched air having a higher oxygen concentration than the first liquefied air, and the liquid oxygen-enriched air and the first nitrogen gas obtained in the low-pressure rectification process are heated. The first nitrogen gas liquefaction step and the low-pressure rectification step, wherein the first nitrogen gas is liquefied and the oxygen-enriched air is vaporized and the liquefied first nitrogen gas is used as the reflux liquid of the first intermediate pressure rectification step. A simulated air compression process in which the simulated air obtained in step 1 is heated with raw material air and then compressed. The pseudo air cooled after compression in the pseudo air compression step is separated into second nitrogen gas and second liquefied air, and a portion of the second nitrogen gas is heated with the pseudo air after compression, and then the second product nitrogen gas The second intermediate pressure rectification step collected as the second intermediate pressure rectification step and the second nitrogen gas obtained in the second intermediate pressure rectification step are heat exchanged with the second liquefied air to liquefy the second nitrogen gas and at the same time the second liquefied air The second nitrogen gas liquefaction step, in which the vaporized and liquefied second nitrogen gas is used as a reflux liquid in the second intermediate pressure rectification step, and the vaporized second liquefied air is heated after being compressed with pseudo air after compression, and And a liquid injection step of injecting a part of the liquid oxygen-enriched air obtained in the low-pressure rectification step into the second liquefied air.
[0016]
Furthermore, in the nitrogen production method of the present invention, the step of obtaining the cold necessary for the operation for carrying out the nitrogen production method by adiabatic expansion or the cold necessary for the operation is performed. From outside Low temperature liquefied gas To process fluids Injection In It is characterized by including a process of obtaining more. Further, the purity of the first product nitrogen gas and the purity of the second product nitrogen gas can be made different so that the pressure of the first product nitrogen gas and the pressure of the second product nitrogen gas are different. It can also be.
[0017]
A nitrogen production apparatus according to the present invention has, as a first configuration, a nitrogen production apparatus that separates nitrogen by subjecting compressed, refined, and cooled raw material air to low-temperature liquefaction rectification, and a compressor that compresses the raw material air. Purification equipment for purifying the raw material air, a main heat exchanger for cooling the purified raw material air, and a first intermediate pressure rectification column for separating the cooled raw material air into first nitrogen gas and first liquefied air A low-pressure rectification column that separates the first liquefied air into simulated air having an oxygen concentration close to the atmosphere and oxygen-enriched air having a higher oxygen concentration than the first liquefied air, and a rectification of the first intermediate-pressure rectification column The first nitrogen gas and the liquid oxygen-enriched air are subjected to heat exchange in order to generate the rectifying column reflux liquid necessary for the rectification and the rectifying column rising gas necessary for the rectification of the low pressure rectifying column. A first condenser that gasifies liquid oxygen-enriched air at the same time, and pseudo air A pseudo air compressor that compresses at a temperature; a second medium pressure rectification tower that separates the pseudo air cooled by the main heat exchanger after compression into second nitrogen gas and second liquefied air; and a second medium pressure rectification The second nitrogen gas is liquefied by indirect heat exchange between the second nitrogen gas and the second liquefied air in order to produce a rectifying column reflux liquid necessary for rectification of the tower, and at the same time the second liquefied air is gasified. A two-condenser, a pipe for extracting a part of oxygen-enriched air in the form of gas from the lower part of the low-pressure rectification column and heating it with the main heat exchanger, and a first medium-pressure rectification column After depressurizing the first liquefied air derived from the pipe that collects the first nitrogen gas derived from the top as the first product nitrogen gas after heating in the main heat exchanger, and the first intermediate pressure rectification column The pipe to be introduced to the upper part of the low-pressure rectification column and the pseudo air derived from the upper part of the low-pressure rectification column are heated by the main heat exchanger and then turned to the pseudo air compressor. A pipe to be introduced, a pipe to be introduced into the second intermediate pressure rectification tower after cooling the compressed pseudo air by the main heat exchanger, and a second nitrogen derived from the upper part of the second intermediate pressure rectification tower From the pipe where the gas is heated in the main heat exchanger and then collected as second product nitrogen gas, from the lower part of the low-pressure rectification column and from the lower part of the low-pressure rectification column A conduit that joins the derived second liquefied air and introduces it into the second condenser; and a conduit that is heated after the second liquefied air gasified by the second condenser is heated by the main heat exchanger; It is characterized by having.
[0018]
Further, the second configuration of the nitrogen production apparatus of the present invention includes a compressor for compressing raw material air and a compression in a nitrogen production apparatus for separating nitrogen by subjecting the compressed, purified, and cooled raw material air to low-temperature liquefaction rectification. Purification equipment for purifying the purified raw material air, a main heat exchanger for cooling the purified raw material air, and first medium pressure rectification for separating the cooled raw material air into first nitrogen gas and first liquefied air A column, a low-pressure rectification column that separates the first liquefied air into simulated air having an oxygen concentration close to the atmosphere and oxygen-enriched air having a higher oxygen concentration than the first liquefied air, In order to produce the rectifying column reflux liquid necessary for the distillation and the rectifying column rising gas necessary for the rectification of the low-pressure rectifying column, the first nitrogen gas and the liquid oxygen-enriched air are subjected to heat exchange to form the first nitrogen. A first condenser that liquefies gas and gasifies liquid oxygen-enriched air at the same time; A pseudo air compressor that compresses the air at room temperature, a second main heat exchanger that cools the compressed pseudo air, and a second nitrogen gas and second liquefied air that is cooled by the second main heat exchanger. And the second nitrogen gas and the second liquefied air are subjected to heat exchange in order to produce a second intermediate pressure rectification column that is separated into a rectification column and a rectification column reflux liquid necessary for the rectification of the second intermediate pressure rectification column. The second condenser that liquefies the second nitrogen gas at the same time and the second liquefied air at the same time, and a part of the oxygen-enriched air gasified by the first condenser are derived from the lower part of the low-pressure rectification column in the gaseous state. The first product nitrogen gas is heated after the main heat exchanger heats the first nitrogen gas led out from the upper part of the first intermediate pressure rectification column and the conduit that is heated after heating in the main heat exchanger A pipe for collecting the first liquefied air derived from the lower part of the first intermediate pressure rectification column and introducing the first liquefied air to the upper part of the low pressure rectification column after depressurization; Heat the simulated air derived from the main section with the main heat exchanger and introduce it into the simulated air compressor. After cooling the compressed pseudo air with the second main heat exchanger, A pipe for introducing into the distillation column, a pipe for collecting the second nitrogen gas derived from the upper part of the second intermediate pressure rectification column with the second main heat exchanger and then collecting it as the second product nitrogen gas, A conduit that joins oxygen-enriched air derived from the lower part of the low-pressure rectification column in a liquid state and second liquefied air derived from the lower part of the second intermediate-pressure rectification column and introduces them into the second condenser; The second liquefied air gasified by the condenser is heated by the second main heat exchanger, and then the conduit is led out.
[0019]
Furthermore, the nitrogen production apparatus of the present invention is an expansion turbine that generates cold necessary for operation of the nitrogen production apparatus or a low-temperature liquefied gas for supplying cold necessary for operation of the nitrogen production apparatus. To process fluid It is characterized by having a conduit for injection. Further, a pipe for leading the liquefied first nitrogen gas or second nitrogen gas as product liquefied nitrogen is provided, and the first intermediate pressure rectification column and the second intermediate pressure rectification column are one cold storage. It is characterized in that it is stored in an outer tank or that the first intermediate pressure rectification tower and the second intermediate pressure rectification tower are stored in different cold storage outer tanks.
[0020]
In addition, when supplying product nitrogen gas, if the purity and pressure of both product nitrogen gas are the same, what is necessary is just to join each outlet line to one product gas outlet line. At this time, when the pressures of the two product nitrogen gases before the merging are different, a pressure reducing valve may be provided in the product nitrogen gas outlet pipe having the higher pressure. In addition, in order to collect product nitrogen gas with different purity, the number of theoretical plates of the first intermediate pressure rectification column and the second intermediate pressure rectification column may be different, or the amount of nitrogen gas collected with respect to raw air or simulated air may be set differently. It can be done by making it different.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system diagram showing a first embodiment of a nitrogen production apparatus to which the nitrogen production method of the present invention is applied. The nitrogen production apparatus includes, as main equipment, a main heat exchanger 21 that cools raw material air, and a first intermediate pressure rectification tower 22 that separates the cooled raw material air into first nitrogen gas and first liquefied air. A low-pressure rectification column 23 that separates the first liquefied air into pseudo air having an oxygen concentration close to the atmosphere and oxygen-enriched air having a higher oxygen concentration than the first liquefied air, and pseudo air that compresses the pseudo air at room temperature. A compressor 24 and a second intermediate pressure rectification tower 25 that separates the pseudo air cooled after compression into second nitrogen gas and second liquefied air are provided. Each device can use this type of device used conventionally.
[0022]
First, the raw air compressed to a pressure set in advance by the compressor 31, for example, 0.9 MPa, is removed from the high-boiling impurities such as water and carbon dioxide by the MS adsorber in the purification equipment 32, for example, It becomes 0.86 MPa and is introduced into the main heat exchanger 21 and is cooled to a preset temperature, for example, −167 ° C., through indirect heat exchange with various low-temperature return gases.
[0023]
The cooled raw material air is introduced into the lower part of the first intermediate pressure rectification column 22 through the pipe line 51, and the first intermediate pressure rectification step in the first intermediate pressure rectification column 22 is used to The first nitrogen gas and the first liquefied air at the bottom of the column are separated. The first nitrogen gas at the top of the tower is extracted into a pipe 52, a part of which is branched into a pipe 53 and introduced into the main heat exchanger 21, and is heated to room temperature by indirect heat exchange with raw material air or the like. After being heated, the first product nitrogen gas N1 is collected from the pipe line 54 at 0.82 MPa.
[0024]
The first liquefied air at the bottom of the column is extracted to the pipe 55, and after being reduced to a pressure set in advance by the pressure reducing valve 33, for example, 0.30 MPa, is introduced into the upper portion of the low pressure rectification column 23, and the low pressure By the low-pressure rectification step in the rectifying column 23, the air is separated into pseudo air at the top of the column having an oxygen concentration close to the atmosphere and liquid oxygen-enriched air at the bottom of the column having a higher oxygen concentration than the first liquefied air.
[0025]
A first condenser 34 for performing a first nitrogen gas liquefaction step is provided at the bottom of the low-pressure rectification column 23, and the first condenser 34 branches from the pipe 52 to the pipe 56. Nitrogen gas and liquid oxygen-enriched air at the bottom of the column undergo indirect heat exchange, and the first nitrogen gas is liquefied and simultaneously oxygen-enriched air is vaporized. The liquefied first nitrogen gas (first liquefied nitrogen) is introduced into the top of the first intermediate pressure rectification tower 22 through the pipe line 57 to become a reflux liquid, and the vaporized oxygen-enriched air is supplied to the low pressure rectification tower. 23 ascending gas.
[0026]
A part of the gaseous oxygen-enriched air rising in the low-pressure rectification column 23 is extracted into the pipe 58 and a part thereof is introduced into the main heat exchanger 21 through the pipe 59. The oxygen-enriched air heated to the intermediate temperature in the main heat exchanger 21 is introduced into the expansion turbine 35 and adiabatically expanded to, for example, 0.13 MPa to generate cold necessary for the operation of the apparatus. The oxygen-enriched air that has undergone this cold generation process merges with the oxygen-enriched air branched from the line 58 via the valve 36 via the line 60, passes through the main heat exchanger 21, and is a cooling source such as raw air. After being heated to room temperature, the exhaust gas W is discharged from the pipe 61. A part of the exhaust gas is used as a regeneration gas for the purification equipment 32.
[0027]
The pseudo air extracted from the top of the low pressure rectification tower 23 to the pipe line 62 is heated to room temperature by the main heat exchanger 21, and then the entire amount is simulated air compressed by the pseudo air compressor 24 during rated operation. According to the process, the pressure is compressed to a preset pressure, for example, 0.86 MPa. The compressed pseudo air is again introduced into the main heat exchanger 21 from the pipe line 63, cooled to −167 ° C., and introduced into the lower part of the second intermediate pressure rectification tower 25 through the pipe line 64.
[0028]
By the second intermediate pressure rectification step in the second intermediate pressure rectification tower 25, the pseudo air is separated into second nitrogen gas at the top of the tower and second liquefied air at the bottom of the tower. The second nitrogen gas at the top of the tower is extracted into a pipe 65, a part of which is branched into a pipe 66 and introduced into the main heat exchanger 21, and is heated to room temperature by indirect heat exchange with raw material air or the like. After being heated, it is collected from the pipe line 67 as a second product nitrogen gas N2 of 0.82 MPa.
[0029]
The second liquefied air at the bottom of the column is extracted to the pipe 68, and after the pressure is reduced to a preset pressure, for example, 0.13 MPa, by the pressure reducing valve 37, the second condenser 38 that performs the second nitrogen gas liquefaction step. To be introduced. The second liquefied air is supplied with the liquid oxygen-enriched air extracted from the bottom of the low-pressure rectification column 23 to the pipe 69 by the liquid injection step so as to have the same pressure as the second liquefied air by the pressure reducing valve 39. It is injected after being decompressed.
[0030]
A second nitrogen gas branched from the pipe 65 to the pipe 70 is introduced into the second condenser 38, and the second nitrogen gas and the second liquefied air perform indirect heat exchange, so that the second nitrogen At the same time as the gas is liquefied, the second liquefied air is vaporized. The liquefied second nitrogen gas (second liquefied nitrogen) is introduced into the top of the second intermediate pressure rectification tower 25 through the pipe line 71 to become a reflux liquid, and the vaporized second liquefied air passes through the pipe line 72. As a result, the oxygen-enriched air exiting the expansion turbine 35 joins and is discharged.
[0031]
When performing a significant weight reduction operation in the nitrogen production apparatus thus formed, the simulated air compressor 24 is stopped, the operation of the second intermediate pressure rectification tower 25 is stopped, and the simulated air is discharged from the valve 40. At the same time, the injection of liquid oxygen-enriched air from the pipe 69 is stopped, and the operation for producing the product nitrogen gas is performed only by the first intermediate pressure rectification column 22. As a result, the amount of product nitrogen gas collected is reduced by the amount corresponding to the second product nitrogen gas N2 from the second intermediate pressure rectification column 25. Furthermore, if the operation range of the first intermediate pressure rectification column 22 is 100% to 60% as in the prior art, the amount of the first product nitrogen gas collected from the first intermediate pressure rectification column 22 is set at the rated operation. Can be reduced to 60%. Therefore, the amount of product nitrogen gas collected can be reduced to 43% of the rated operation by stopping the pseudo air compressor 24 and reducing the first intermediate pressure rectification column 22.
[0032]
Table 3 shows an example of process values when the raw material air amount during rated operation is 100 in this nitrogen production apparatus. Further, Table 4 shows an example of the process value at the time of the maximum weight reduction operation. In Tables 3 and 4, A to O represent points A to O in FIG. Table 5 shows the result of comparing the weight loss width and the compressor theoretical power in the conventional circulating nitrogen production process and the nitrogen production process shown in the present embodiment. In Table 5, the gas compressor indicates the exhaust gas compressor 3 in the conventional example and the pseudo air compressor 24 in the present embodiment.
[0033]
[Table 3]
Figure 0004230168
[0034]
[Table 4]
Figure 0004230168
[0035]
[Table 5]
Figure 0004230168
[0036]
Further, the collection and supply of product nitrogen gas is performed in two towers, a first intermediate pressure rectification tower 22 and a second intermediate pressure rectification tower 25, and the second intermediate pressure rectification tower 25 is compressed by a pseudo air compressor 24. Since the latter pseudo air is used, the operation of each of the two towers can be performed independently irrespective of the operation of the first intermediate pressure rectification tower 22 using only the raw air.
[0037]
Therefore, by collecting each product nitrogen gas of the same purity and the same pressure, it becomes possible to cope with the large demand fluctuation as described above. On the other hand, the operating conditions in both towers and the number of theoretical plates in both towers Depending on the setting, product nitrogen gas of different purity and pressure can be collected from each column. That is, it is possible to set so that high-purity product nitrogen gas is collected from one medium-pressure rectification column and general-purpose purity product nitrogen gas is collected from the other medium-pressure rectification column.
[0038]
Further, by making the sampling pressures of both product nitrogen gases the same, the first and second product nitrogen gases can be easily merged, and can be fed together into one product gas outlet line. The pressure of the second product nitrogen gas can be set to a pressure different from the pressure of the first product nitrogen gas by appropriately setting the compression pressure in the pseudo air compressor 24. In addition, what is necessary is just to provide a pressure-reduction valve in the pipe line of high-pressure product nitrogen gas, and to make it the same pressure, when both product nitrogen gas from which collection pressures differ is merged.
[0039]
Furthermore, depending on the setting of the amount of cold generated and the operating conditions, a part of the first and second liquefied nitrogen liquefied in each condenser and introduced into each intermediate pressure rectification column as a reflux liquid is introduced before the rectification column is introduced. Alternatively, it can be extracted after introduction and collected as product liquefied nitrogen after introduction.
[0040]
FIG. 2 is a system diagram showing a second embodiment of the present invention. In the following description, the same components as those in the nitrogen production apparatus shown in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0041]
The nitrogen production apparatus shown in the present embodiment includes, as main heat exchangers, a first main heat exchanger 21 related to the first intermediate pressure rectification column 22 and the low pressure rectification column 23, and a second intermediate pressure rectification column 25. And a second main heat exchanger 26 related to the above. That is, the pseudo-air compressor 24 introduced into the second intermediate pressure rectification tower 25 is compressed with the pseudo air compressor 63, and the second nitrogen gas separated by the second intermediate pressure rectification tower 25 is converted into the second product nitrogen. The second main heat exchanger 26 is provided with a pipeline 67 for collecting the gas N2 and a pipeline 72 for the second liquefied air that is vaporized and discharged by the second condenser 38.
[0042]
Furthermore, in the first embodiment, all the low-temperature equipment is housed in one cold outer tank 81. In this embodiment, the first intermediate pressure rectification tower 22, the low pressure rectification tower 23, the first main The low-temperature equipment related to the heat exchanger 21 and the low-temperature equipment related to the second intermediate pressure rectification tower 25 and the second main heat exchanger 26 are respectively stored in different cold insulation outer tanks 82 and 83, and both cold insulation outer tanks. A pipe line 69 extending between them is formed by a heat insulating pipe and connected.
[0043]
By separately forming the cold insulation outer tank in this way, for example, when the demand for the product nitrogen gas at the supply destination is relatively small at the initial stage of factory construction, the equipment on the second intermediate pressure rectification tower 25 side or the cold insulation is used. Without installing the outer tank 83, only the equipment on the first intermediate pressure rectification tower 22 side is installed and formed so as to collect the product nitrogen gas from here, and when the demand for the product nitrogen gas increases, By adding equipment related to the second intermediate pressure rectification column 25 and the cold insulation outer tank 83 so as to collect product nitrogen gas from both intermediate pressure rectification columns, the initial investment can be reduced. .
[0044]
FIG. 3 is a system diagram showing a third embodiment of the present invention. In the nitrogen production apparatus shown in this embodiment, the cooling required for the operation of the apparatus is obtained by injecting a low-temperature liquefied gas from the outside instead of obtaining the adiabatic expansion in the expansion turbine shown in both of the above embodiments. An example is shown.
[0045]
That is, the gaseous oxygen-enriched air extracted from the low-pressure rectification column 23 to the pipe 58 is formed so that the entire amount thereof is introduced from the valve 36 to the main heat exchanger 21 through the pipe 60 and from the outside. By providing a pipe line 100 for injecting the low-temperature liquefied gas into the apparatus, and injecting the low-temperature liquefied gas from the pipe line 100 to an appropriate location in the apparatus according to the type, composition, and pressure of the low-temperature liquefied gas. To supply cold.
[0046]
For example, in the case of liquefied nitrogen having a purity corresponding to the purity of the product nitrogen gas as the low-temperature liquefied gas injected from the outside and having a pressure corresponding to the operating pressure of the first intermediate pressure rectification column 22, the pipe line 100 can be injected into the first intermediate pressure rectification tower 22 via the pipe line 101. Similarly, it is also possible to inject into the second intermediate pressure rectification column 25, and further, the first liquefied nitrogen flowing through the pipe line 57 and the second liquefied nitrogen flowing through the pipe line 71, not directly to the rectification column. Can also be joined. The liquefied nitrogen injected into the first and second intermediate pressure rectification towers in this way can be collected as part of product nitrogen gas after being used for cold supply.
[0047]
Further, in the case of low purity liquefied nitrogen or liquefied air, or in the case of liquefied nitrogen having a certain level of purity but low pressure, the pipe 55 is connected to the pipe 55 via the valve 102 and the pipe 103. Can be combined with the first liquefied air after depressurization flowing through the pipe 100, or can be combined with the second liquefied air in the pipe line 68 from the pipe line 100 through the pipe line 104 and the valve 105. The locations can be combined appropriately. Further, the pipe for injecting the low-temperature liquefied gas can be provided in the apparatus in which the expansion turbine is installed. For example, it may be used during maintenance of the expansion turbine, or both of them may be used together.
[0048]
In addition, as shown in the second embodiment, when the cold outer tank is divided, the expansion turbine 35 generates cold necessary for operation on the first intermediate pressure rectification tower 22 side, It is also possible to set so that the cooling required for the operation on the second intermediate pressure rectification column 25 side can be obtained by injection of a low-temperature liquefied gas from the outside. In this case, since the pipe 69 for cold replenishment can be omitted, it is not necessary to provide a low-temperature pipe extending over both cold insulation outer tanks, and heat loss and equipment cost can be reduced.
[0049]
【The invention's effect】
As described above, according to the present invention, the amount of product nitrogen gas collected can be greatly varied without deteriorating the basic unit, while using the conventionally used equipment as it is. Further, it is possible to collect product nitrogen gas having different pressure and different purity as required.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a first embodiment of a nitrogen production apparatus to which a nitrogen production method of the present invention is applied.
FIG. 2 is a system diagram showing a second embodiment of the nitrogen production apparatus of the present invention.
FIG. 3 is a system diagram showing a third embodiment of the nitrogen production apparatus of the present invention.
FIG. 4 is a system diagram showing an example of a conventional circulating nitrogen production apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 21 ... Main heat exchanger, 22 ... First intermediate pressure rectification tower, 23 ... Low pressure rectification tower, 24 ... Pseudo air compressor, 25 ... Second intermediate pressure rectification tower, 26 ... Second main heat exchanger, DESCRIPTION OF SYMBOLS 31 ... Compressor, 32 ... Purification equipment, 34 ... First condenser, 35 ... Expansion turbine, 38 ... Second condenser, 81, 82, 83 ... Cold storage outer tank, 100, 101, 103, 104 ... Low temperature liquefied gas Pipe for injection, N1 ... first product nitrogen gas, N2 ... second product nitrogen gas, W ... exhaust gas

Claims (13)

圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造方法において、圧縮、精製、冷却した原料空気を第一窒素ガスと第一液化空気とに分離して第一窒素ガスの一部を加温してから第一製品窒素ガスとして採取する第一中圧精留工程と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留工程と、低圧精留工程で得た液状の酸素富化空気と第一窒素ガスとを熱交換させて第一窒素ガスを液化すると同時に酸素富化空気を気化し、液化した第一窒素ガスを第一中圧精留工程の還流液とする第一窒素ガス液化工程と、低圧精留工程で得た擬似空気を加温してから圧縮する擬似空気圧縮工程と、擬似空気圧縮工程で圧縮後に冷却した擬似空気を第二窒素ガスと第二液化空気とに分離して第二窒素ガスの一部を加温してから第二製品窒素ガスとして採取する第二中圧精留工程と、第二中圧精留工程で得た第二窒素ガスと第二液化空気とを熱交換させて第二窒素ガスを液化すると同時に第二液化空気を気化し、液化した第二窒素ガスを第二中圧精留工程の還流液とし、気化した第二液化空気を加温してから排出する第二窒素ガス液化工程と、低圧精留工程で得た液状の酸素富化空気の一部を第二液化空気に注入する液注入工程とを含むことを特徴とする窒素製造方法。In a nitrogen production method for separating nitrogen by subjecting compressed, refined, and cooled raw material air to low-temperature liquefaction rectification, the compressed, purified, and cooled raw material air is separated into a first nitrogen gas and a first liquefied air. The first intermediate pressure rectification process, in which a part of the nitrogen gas is heated and then collected as the first product nitrogen gas, and the oxygen concentration of the first liquefied air is nearer to the atmosphere than the simulated air and the first liquefied air The first nitrogen gas is liquefied by heat exchange between the low-pressure rectification process separated into high oxygen-enriched air and the liquid oxygen-enriched air obtained in the low-pressure rectification process and the first nitrogen gas. The first nitrogen gas liquefaction process using vaporized liquefied air and the liquefied first nitrogen gas as the reflux liquid in the first intermediate pressure rectification process and the pseudo air obtained in the low pressure rectification process are heated and then compressed. The simulated air compression process and the simulated air cooled after compression in the simulated air compression process A second intermediate pressure rectification step, in which a portion of the second nitrogen gas is heated after being separated into dinitrogen gas and second liquefied air, and then collected as a second product nitrogen gas, and a second intermediate pressure rectification step The second nitrogen gas obtained in step 2 and the second liquefied air are heat-exchanged to liquefy the second nitrogen gas, and at the same time the second liquefied air is vaporized, and the liquefied second nitrogen gas is returned to the second intermediate pressure rectification step. A second nitrogen gas liquefaction step for heating and discharging the vaporized second liquefied air, and a liquid for injecting a part of the liquid oxygen-enriched air obtained in the low-pressure rectification step into the second liquefied air A nitrogen production method including an implantation step. 圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造方法において、圧縮、精製、冷却した原料空気を第一窒素ガスと第一液化空気とに分離して第一窒素ガスの一部を原料空気で加温してから第一製品窒素ガスとして採取する第一中圧精留工程と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留工程と、低圧精留工程で得た液状の酸素富化空気と第一窒素ガスとを熱交換させて第一窒素ガスを液化すると同時に酸素富化空気を気化し、液化した第一窒素ガスを第一中圧精留工程の還流液とする第一窒素ガス液化工程と、低圧精留工程で得た擬似空気を原料空気で加温してから圧縮する擬似空気圧縮工程と、擬似空気圧縮工程で圧縮後に冷却した擬似空気を第二窒素ガスと第二液化空気とに分離して第二窒素ガスの一部を圧縮後の擬似空気で加温してから第二製品窒素ガスとして採取する第二中圧精留工程と、第二中圧精留工程で得た第二窒素ガスと第二液化空気とを熱交換させて第二窒素ガスを液化すると同時に第二液化空気を気化し、液化した第二窒素ガスを第二中圧精留工程の還流液とし、気化した第二液化空気を圧縮後の擬似空気で加温してから排出する第二窒素ガス液化工程と、低圧精留工程で得た液状の酸素富化空気の一部を第二液化空気に注入する液注入工程とを含むことを特徴とする窒素製造方法。In a nitrogen production method for separating nitrogen by subjecting compressed, refined, and cooled raw material air to low-temperature liquefaction rectification, the compressed, purified, and cooled raw material air is separated into a first nitrogen gas and a first liquefied air. A first intermediate pressure rectification process in which a part of nitrogen gas is heated with raw material air and then collected as the first product nitrogen gas, and the first liquefied air is made up of simulated air having an oxygen concentration close to the atmosphere and the first liquefied air. When the first nitrogen gas is liquefied by heat exchange between the low-pressure rectification process that separates the oxygen-enriched air having a high oxygen concentration and the liquid oxygen-enriched air obtained in the low-pressure rectification process and the first nitrogen gas. At the same time, oxygen-enriched air is vaporized, and the first nitrogen gas liquefaction step using the liquefied first nitrogen gas as the reflux liquid in the first intermediate pressure rectification step and the simulated air obtained in the low-pressure rectification step are added with the raw air. After compressed in the pseudo air compression process that compresses after warming and the pseudo air compression process Second intermediate pressure in which the cooled pseudo air is separated into second nitrogen gas and second liquefied air, and a portion of the second nitrogen gas is heated with compressed pseudo air and then collected as second product nitrogen gas The second nitrogen gas and the second liquefied air obtained in the rectification step and the second intermediate pressure rectification step are heat-exchanged to liquefy the second nitrogen gas, and at the same time, the second liquefied air is vaporized and liquefied. Nitrogen gas was used as the reflux liquid in the second intermediate pressure rectification process, and the vaporized second liquefied air was heated in the compressed pseudo air and then discharged and obtained in the low pressure rectification process. And a liquid injection step of injecting a part of the liquid oxygen-enriched air into the second liquefied air. 前記窒素製造方法を実施する装置の運転に必要な寒冷を断熱膨張により得る工程を含むことを特徴とする請求項１又は２記載の窒素製造方法。 The method for producing nitrogen according to claim 1 or 2, further comprising a step of obtaining cold necessary for operation of an apparatus for carrying out the method for producing nitrogen by adiabatic expansion. 前記窒素製造方法を実施する装置の運転に必要な寒冷を外部からの低温液化ガスのプロセス流体への注入により得る工程を含むことを特徴とする請求項１又は２記載の窒素製造方法。Claim 1 or 2 nitrogen method according to, characterized in that it comprises a further step of obtaining the cold necessary for the operation of an apparatus for carrying out the nitrogen producing method for injection into the process fluid of the low-temperature liquefied gas from the outside. 前記第一製品窒素ガスの純度と前記第二製品窒素ガスの純度とが異なることを特徴とする請求項１又は２記載の窒素製造方法。The nitrogen production method according to claim 1 or 2, wherein the purity of the first product nitrogen gas is different from the purity of the second product nitrogen gas. 前記第一製品窒素ガスの圧力と前記第二製品窒素ガスの圧力とが異なることを特徴とする請求項１又は２記載の窒素製造方法。The nitrogen production method according to claim 1 or 2, wherein the pressure of the first product nitrogen gas is different from the pressure of the second product nitrogen gas. 圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造装置において、原料空気を圧縮する圧縮機と、圧縮された原料空気を精製する精製設備と、精製された原料空気を冷却する主熱交換器と、冷却された原料空気を第一窒素ガスと第一液化空気とに分離する第一中圧精留塔と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留塔と、第一中圧精留塔の精留に必要な精留塔還流液及び低圧精留塔の精留に必要な精留塔上昇ガスを生成するために第一窒素ガスと液状の酸素富化空気とを熱交換させて第一窒素ガスを液化すると同時に液状の酸素富化空気をガス化する第一凝縮器と、擬似空気を常温で圧縮する擬似空気圧縮機と、圧縮後に主熱交換器で冷却した擬似空気を第二窒素ガスと第二液化空気とに分離する第二中圧精留塔と、第二中圧精留塔の精留に必要な精留塔還流液を生成するために第二窒素ガスと第二液化空気とを間接熱交換させて第二窒素ガスを液化すると同時に第二液化空気をガス化する第二凝縮器と、低圧精留塔の下部から酸素富化空気の一部をガス状で導出して主熱交換器で加温してから導出する管路と、第一中圧精留塔の上部から導出した第一窒素ガスを主熱交換器で加温してから第一製品窒素ガスとして採取する管路と、第一中圧精留塔の下部から導出した第一液化空気を減圧後に低圧精留塔の上部に導入する管路と、低圧精留塔の上部から導出した擬似空気を主熱交換器で加温してから擬似空気圧縮機に導入する管路と、圧縮後の擬似空気を主熱交換器で冷却してから第二中圧精留塔に導入する管路と、第二中圧精留塔の上部から導出した第二窒素ガスを主熱交換器で加温してから第二製品窒素ガスとして採取する管路と、低圧精留塔の下部から液状で導出した酸素富化空気と第二中圧精留塔の下部から導出した第二液化空気とを合流させて第二凝縮器に導入する管路と、第二凝縮器でガス化した第二液化空気を主熱交換器で加温してから導出する管路とを備えていることを特徴とする窒素製造装置。In a nitrogen production device that separates nitrogen by low-temperature liquefaction rectification of compressed, refined, and cooled raw material air, a compressor that compresses the raw material air, a purification facility that purifies the compressed raw material air, and a purified raw material A main heat exchanger that cools the air, a first intermediate pressure rectification tower that separates the cooled raw air into first nitrogen gas and first liquefied air, and a simulated oxygen concentration near the atmosphere of the first liquefied air A low-pressure rectification column that separates into air and oxygen-enriched air having a higher oxygen concentration than the first liquefied air, and a rectification column reflux liquid and a low-pressure rectification column that are necessary for the rectification of the first intermediate-pressure rectification column. In order to generate the rectifying tower rising gas necessary for rectification, the first nitrogen gas and the liquid oxygen-enriched air are heat-exchanged to liquefy the first nitrogen gas and at the same time, the liquid oxygen-enriched air is gasified. The first condenser, the pseudo air compressor that compresses the pseudo air at room temperature, and the main Generates second intermediate pressure rectification column that separates pseudo air cooled by exchanger into second nitrogen gas and second liquefied air, and rectification column reflux liquid required for rectification of second intermediate pressure rectification column In order to achieve this, the second nitrogen gas and the second liquefied air are indirectly heat-exchanged to liquefy the second nitrogen gas, and at the same time the second liquefied air is gasified. A part of the liquefied air is derived in the form of gas and heated after being heated by the main heat exchanger, and the first nitrogen gas derived from the upper part of the first intermediate pressure rectification column is removed by the main heat exchanger. A pipe for collecting the first product nitrogen gas after heating, a pipe for introducing the first liquefied air derived from the lower part of the first intermediate pressure rectification column into the upper part of the low pressure rectification column after depressurization, and a low pressure Heating the simulated air derived from the upper part of the rectification tower in the main heat exchanger and then introducing it into the simulated air compressor and the compressed air after the compression The second product nitrogen after heating in the main heat exchanger the second nitrogen gas led out from the upper part of the second medium pressure rectification column and the pipe line to be cooled to the second intermediate pressure rectification column A pipe to be collected as a gas, oxygen-enriched air led out from the lower part of the low-pressure rectification column, and second liquefied air led out from the lower part of the second intermediate-pressure rectification column are merged into the second condenser An apparatus for producing nitrogen, comprising: a pipe line to be introduced; and a pipe line to which the second liquefied air gasified by the second condenser is heated after being heated by the main heat exchanger. 圧縮、精製、冷却した原料空気を低温液化精留することによって窒素を分離する窒素製造装置において、原料空気を圧縮する圧縮機と、圧縮された原料空気を精製する精製設備と、精製された原料空気を冷却する主熱交換器と、冷却された原料空気を第一窒素ガスと第一液化空気とに分離する第一中圧精留塔と、第一液化空気を大気に近い酸素濃度の擬似空気と第一液化空気よりも酸素濃度の高い酸素富化空気とに分離する低圧精留塔と、第一中圧精留塔の精留に必要な精留塔還流液及び低圧精留塔の精留に必要な精留塔上昇ガスを生成するために第一窒素ガスと液状の酸素富化空気とを熱交換させて第一窒素ガスを液化すると同時に液状の酸素富化空気をガス化する第一凝縮器と、擬似空気を常温で圧縮する擬似空気圧縮機と、圧縮後の擬似空気を冷却する第二主熱交換器と、第二主熱交換器で冷却された擬似空気を第二窒素ガスと第二液化空気とに分離する第二中圧精留塔と、第二中圧精留塔の精留に必要な精留塔還流液を生成するために第二窒素ガスと第二液化空気とを熱交換させて第二窒素ガスを液化すると同時に第二液化空気をガス化する第二凝縮器と、第一凝縮器でガス化した酸素富化空気の一部を低圧精留塔の下部からガス状で導出して主熱交換器で加温してから導出する管路と、第一中圧精留塔の上部から導出した第一窒素ガスを主熱交換器で加温してから第一製品窒素ガスとして採取する管路と、第一中圧精留塔の下部から導出した第一液化空気を減圧後に低圧精留塔の上部に導入する管路と、低圧精留塔の上部から導出した擬似空気を主熱交換器で加温してから擬似空気圧縮機に導入する管路と、圧縮後の擬似空気を第二主熱交換器で冷却してから第二中圧精留塔に導入する管路と、第二中圧精留塔の上部から導出した第二窒素ガスを第二主熱交換器で加温してから第二製品窒素ガスとして採取する管路と、低圧精留塔の下部から液状で導出した酸素富化空気と第二中圧精留塔の下部から導出した第二液化空気とを合流させて第二凝縮器に導入する管路と、第二凝縮器でガス化した第二液化空気を第二主熱交換器で加温してから導出する管路とを備えていることを特徴とする窒素製造装置。In a nitrogen production device that separates nitrogen by low-temperature liquefaction rectification of compressed, refined, and cooled raw material air, a compressor that compresses the raw material air, a purification facility that purifies the compressed raw material air, and a purified raw material A main heat exchanger that cools the air, a first intermediate pressure rectification column that separates the cooled raw material air into first nitrogen gas and first liquefied air, and a simulated oxygen concentration near the atmosphere of the first liquefied air A low-pressure rectification column that separates into air and oxygen-enriched air having a higher oxygen concentration than the first liquefied air, and a rectification column reflux liquid and a low-pressure rectification column that are necessary for the rectification of the first intermediate-pressure rectification column. In order to generate the rectifying tower rising gas necessary for rectification, the first nitrogen gas and the liquid oxygen-enriched air are heat-exchanged to liquefy the first nitrogen gas and at the same time, the liquid oxygen-enriched air is gasified. A first condenser, a pseudo air compressor that compresses pseudo air at room temperature, and a pseudo air compressor after compression. A second main heat exchanger that cools the air, a second medium-pressure rectification tower that separates the pseudo air cooled by the second main heat exchanger into second nitrogen gas and second liquefied air, The second nitrogen gas and the second liquefied air are heat-exchanged to generate the rectifying column reflux liquid necessary for the rectification of the pressure rectification column, and the second nitrogen gas is liquefied at the same time as the second liquefied air is gasified. The second condenser to be used, and a pipe for extracting a part of the oxygen-enriched air gasified by the first condenser from the lower part of the low-pressure rectification column in a gaseous state and heating it by the main heat exchanger And a pipe for collecting the first nitrogen gas derived from the upper part of the first intermediate pressure rectification column as the first product nitrogen gas after heating in the main heat exchanger, and the lower part of the first intermediate pressure rectification column The first liquefied air derived from the pipe is introduced into the upper part of the low-pressure rectification column after decompression, and the simulated air derived from the upper part of the low-pressure rectification column is heated by the main heat exchanger. A pipeline for introducing the simulated air compressor, a pipeline for cooling the compressed simulated air with the second main heat exchanger and then introducing it to the second intermediate pressure rectification column, and a second intermediate pressure rectification column The second nitrogen gas derived from the upper part is heated by the second main heat exchanger and then collected as the second product nitrogen gas, and the oxygen-enriched air derived from the lower part of the low-pressure rectification column and the second The second liquefied air derived from the lower part of the second intermediate pressure rectification column is joined to introduce the second liquefied air into the second condenser, and the second liquefied air gasified by the second condenser is converted into the second main heat exchanger. A nitrogen production apparatus comprising: a conduit that is heated after being heated. 前記窒素製造装置の運転に必要な寒冷を発生させる膨張タービンを備えていることを特徴とする請求項７又は８記載の窒素製造装置。 The nitrogen production apparatus according to claim 7 or 8, further comprising an expansion turbine that generates cold necessary for operation of the nitrogen production apparatus. 前記窒素製造装置の運転に必要な寒冷を供給するための低温液化ガスをプロセス流体へ注入する管路を備えていることを特徴とする請求項７又は８記載の窒素製造装置。The nitrogen production apparatus according to claim 7 or 8, further comprising a pipe line for injecting a low-temperature liquefied gas for supplying cold necessary for operation of the nitrogen production apparatus into the process fluid . 前記液化した第一窒素ガス又は第二窒素ガスを製品液化窒素として導出する管路を備えていることを特徴とする請求項７又は８記載の窒素製造装置。The nitrogen production apparatus according to claim 7 or 8, further comprising a conduit for deriving the liquefied first nitrogen gas or second nitrogen gas as product liquefied nitrogen. 前記第一中圧精留塔と第二中圧精留塔とが一つの保冷外槽に格納されていることを特徴とする請求項７又は８記載の窒素製造装置。The nitrogen production apparatus according to claim 7 or 8, wherein the first intermediate pressure rectification column and the second intermediate pressure rectification column are stored in a single cold outer tank. 前記第一中圧精留塔と第二中圧精留塔とが異なる保冷外槽に格納されていることを特徴とする請求項７又は８記載の窒素製造装置。The nitrogen production apparatus according to claim 7 or 8, wherein the first intermediate pressure rectification column and the second intermediate pressure rectification column are stored in different cold storage outer tanks.
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