JP3667889B2 - Nitrogen production method and apparatus - Google Patents

Nitrogen production method and apparatus Download PDF

Info

Publication number
JP3667889B2
JP3667889B2 JP21621196A JP21621196A JP3667889B2 JP 3667889 B2 JP3667889 B2 JP 3667889B2 JP 21621196 A JP21621196 A JP 21621196A JP 21621196 A JP21621196 A JP 21621196A JP 3667889 B2 JP3667889 B2 JP 3667889B2
Authority
JP
Japan
Prior art keywords
pressure
nitrogen
path
column
raw material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP21621196A
Other languages
Japanese (ja)
Other versions
JPH1062062A (en
Inventor
雅洋 田村
高司 辰巳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Taiyo Nippon Sanso Corp
Original Assignee
Taiyo Nippon Sanso Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Taiyo Nippon Sanso Corp filed Critical Taiyo Nippon Sanso Corp
Priority to JP21621196A priority Critical patent/JP3667889B2/en
Publication of JPH1062062A publication Critical patent/JPH1062062A/en
Application granted granted Critical
Publication of JP3667889B2 publication Critical patent/JP3667889B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • 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
    • F25J3/04424—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 without thermally coupled high and low pressure columns, i.e. a so-called split columns
    • 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
    • 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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/20—Processes or apparatus using separation by rectification in an elevated pressure multiple column system wherein the lowest pressure column is at a pressure well above the minimum pressure needed to overcome pressure drop to reject the products to atmosphere
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/42—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/02—Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger

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、詳しくは、圧縮，精製，冷却した原料空気を深冷液化精留分離して超高純度窒素を製造する方法及び装置に関する。
【０００２】
【従来の技術】
近年、半導体工場における超高純度窒素の需要が高まっている。この超高純度窒素を製造するための装置として、図３に示すような窒素製造装置が用いられている。この窒素製造装置は、精留塔で空気を深冷液化精留分離することにより超高純度窒素ガスを得るものであって、空気圧縮機１で製品窒素ガスの圧力よりも高い圧力まで昇圧された原料空気は、アフタークーラー２を経て吸着器３に導入され、含有する水分や炭酸ガス等の不純物が除去されて精製された後、主熱交換器４で製品窒素等との熱交換により液化点付近まで冷却されて経路５から精留塔６の下部に導入される。
【０００３】
精留塔６に導入された原料空気は、周知の深冷液化精留分離操作により、塔上部の窒素ガスと、塔底部の酸素富化液化空気とに分離する。塔上部の窒素ガスは、経路７に導出された後に分岐し、経路８に分岐した窒素ガスは、前記主熱交換器４で原料空気を冷却することにより常温に昇温した後、経路９から製品窒素ガスとして採取される。また、経路７から経路１０に分岐した窒素ガスは、凝縮器１１に導入されて凝縮液化し、経路１２を経て精留塔６の頂部に戻されて精留塔６の還流液となる。
【０００４】
前記塔底部の酸素富化液化空気は、経路１３に導出されて減圧弁１４で中間圧力に減圧された後、経路１５と経路１６とに分岐し、経路１５に分岐した酸素富化液化空気が前記凝縮器１１に導入され、前記窒素ガスを液化するための冷却源となり、自身は蒸発気化して酸素富化空気になる。凝縮器１１を導出した酸素富化空気は、経路１６と合流した後、経路１７を経て経路１８と経路１９とに分岐する。経路１８から前記主熱交換器４に導入された酸素富化空気は、中間温度まで昇温して主熱交換器４の中間部から経路２０に導出され、膨張タービン２１で常圧付近まで断熱膨張して寒冷を発生する。
【０００５】
寒冷を発生した酸素富化空気は、経路１９に分岐して減圧弁２２で略常圧に減圧された酸素富化空気と合流した後、経路２３を経て主熱交換器４に導入され、原料空気を冷却することにより常温に昇温して経路２４から導出される。
【０００６】
【発明が解決しようとする課題】
しかし、上述のような窒素製造装置では、製品窒素ガスの圧力が、原料空気の圧力に依存するため、比較的高圧の窒素ガスを得るためには、原料空気の全量を必要な圧力まで圧縮しなければならず、さらに、精留塔において高い圧力で精留分離するために製品収率が低く、原単位も低くなっていた。
【０００７】
また、精留塔を低い圧力で運転して得た窒素ガスを窒素圧縮機で必要な圧力まで昇圧することも行われているが、窒素圧縮機で圧縮する際に製品窒素ガスが汚染されるおそれがあるため、超高純度の窒素ガスを製造するための装置には適用が困難であった。
【０００８】
そこで本発明は、製品収率や原単位の向上を図りながら、超高純度の窒素ガスを高い圧力で採取することができる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。
【０００９】
【課題を解決するための手段】
上記目的を達成するため、本発明の窒素製造方法は、圧縮，精製，冷却した原料空気を精留塔に導入して深冷液化精留分離を行い、原料空気中の窒素を製品として採取する方法において、原料空気の一部を低圧状態で低圧塔に導入して精留し、その塔頂部に分離した窒素ガスを、前記低圧塔底部及び高圧塔底部にそれぞれ分離した酸素富化液化空気を冷却源として凝縮器で液化し、得られた液化窒素を昇圧して高圧塔の頂部に還流液として導入するとともに、該高圧塔の底部に高圧状態の原料空気を導入し、該高圧塔での精留により得られた塔頂部の窒素ガスを製品として採取することを特徴としている。
【００１０】
また、本発明方法は、前記高圧状態の原料空気が、低圧状態に昇圧した原料空気の一部を分岐して所定の高圧状態に昇圧したものであること、あるいは、前記低圧状態の原料空気は、高圧状態に昇圧した原料空気の一部を分岐して膨張タービンで所定の低圧状態まで膨張降圧したものであることを特徴としている。
【００１１】
さらに、本発明の窒素製造装置は、圧縮，精製，冷却した原料空気が導入される低圧塔及び高圧塔を備え、前記低圧塔は、低圧原料空気を塔下部に導入する経路と、塔上部に精留分離した窒素ガスと前記低圧塔底部及び高圧塔底部にそれぞれ精留分離した酸素富化液化空気とを熱交換させて窒素ガスを液化する凝縮器と、凝縮器で液化した液化窒素の一部を還流液として低圧塔頂部に戻す経路と、該液化窒素の残部を液化窒素ポンプで昇圧して前記高圧塔の頂部に還流液として導入する経路とを備え、前記高圧塔は、前記凝縮器からの液化窒素を還流液として塔頂部に導入する前記経路と、高圧原料空気を塔下部に導入する経路と、塔頂部に精留分離した窒素ガスを製品として導出する経路とを備えていることを特徴としている。
【００１２】
【発明の実施の形態】
以下、本発明を、図面を参照してさらに詳細に説明する。まず、図１は、本発明を適用した窒素製造装置の第１形態例を示している。この窒素製造装置は、精留塔として低圧塔３１及び高圧塔３２を有するもので、原料空気の一部を製品収率の良い低圧塔３１に導入して精留分離し、超高純度液化窒素を採取するとともに、この超高純度液化窒素を液化窒素ポンプ３３により昇圧して、残った原料空気が導入される高圧塔３２の還流液として利用することにより、高圧塔３２から高圧の超高純度窒素ガスを得るようにしたものである。
【００１３】
まず、空気圧縮機４１で低圧塔３１の運転圧力に応じた低圧状態に昇圧された原料空気は、アフタークーラー４２を経て吸着器４３に導入され、含有する水分や炭酸ガス等の不純物が除去されて精製された後、経路４４に分岐して主熱交換器４５に導入され、製品窒素等との熱交換により液化点付近まで冷却されて低圧状態のまま経路４６から低圧塔３１の下部に導入される。
【００１４】
低圧塔３１に導入された低圧状態の原料空気は、深冷液化精留分離操作により塔上部の窒素ガスと、塔底部の酸素富化液化空気とに分離する。この低圧塔３１における精留分離においては、従来装置に比べて圧力が低い分だけ比揮発度が改善された状態で運転され、酸素と窒素との分離が良好に行われて窒素の収率が向上する。
【００１５】
低圧塔３１の上部に分離した窒素ガスは、経路４７から凝縮器４８に導入されて凝縮液化し、液化窒素となって経路４９に導出された後に経路５０と経路５１とに分岐し、経路５０の液化窒素は、低圧塔３１の頂部に戻されて低圧塔３１の還流液となる。また、経路５１に分岐した液化窒素は、前記液化窒素ポンプ３３で高圧塔３２の運転圧力、即ち製品窒素ガスの導出圧力に応じた高圧状態に昇圧された後、経路５２から高圧塔３２の頂部に導入され、該高圧塔３２の還流液となる。
【００１６】
前記低圧塔３１の底部の酸素富化液化空気は、経路５３に導出されて減圧弁５４で中間圧力に減圧された後、経路５５と経路５６とに分岐し、経路５５に分岐した酸素富化液化空気が前記凝縮器４８に導入され、前記窒素ガスを液化するための冷却源となり、自身は蒸発気化して酸素富化空気になる。凝縮器４８を導出した酸素富化空気は、経路５６と合流した後、経路５７を経て経路５８と経路５９とに分岐する。経路５８から前記主熱交換器４５に導入された酸素富化空気は、中間温度まで昇温して主熱交換器４５の中間部から経路６０に導出され、膨張タービン６１で常圧付近まで断熱膨張して寒冷を発生する。
【００１７】
寒冷を発生した酸素富化空気は、経路５９に分岐して減圧弁６２で略常圧に減圧された酸素富化空気と合流した後、経路６３を経て主熱交換器４５に導入され、原料空気を冷却することにより常温に昇温して経路６４から導出される。
【００１８】
一方、前記吸着器４３を導出して経路６４に分岐した低圧状態の原料空気は、二次圧縮機６５により製品窒素ガスの導出圧力に対応した高圧状態に昇圧された後、主熱交換器４５で冷却されて経路６６から高圧塔３２の下部に導入される。この高圧塔３２では、下部に導入された高圧状態の原料空気と、前記経路５２から導入された高圧状態の液化窒素とによる精留が行われ、塔上部に超高純度窒素ガスが分離し、塔底部に酸素富化液化空気が分離する。
【００１９】
塔底部から経路６７に導出された酸素富化液化空気は、減圧弁６８で減圧された後に、前記低圧塔３１から経路５３に導出した酸素富化液化空気と合流し、凝縮器４８，膨張タービン６１，主熱交換器４５等を経て経路６４から導出される。
【００２０】
そして、高圧塔３２の上部から経路６９に導出された超高純度窒素ガスは、主熱交換器４５で温度回復した後、製品窒素ガスとして経路７０から採取される。
【００２１】
このように、低圧で製品収率に優れた低圧塔３１で分離した窒素ガスを液化して還流液を得ることにより、従来に比べて還流液量を多くすることができるので、原料空気量を減らすことが可能となり、製品収率の向上が図れる。さらに、原料空気の全量を製品窒素ガスの圧力以上の高圧状態に昇圧しないため、空気圧縮機の所要動力の低減が図れ、特に、製品窒素ガスの圧力が高い場合には、製品収率の向上との相乗効果により、原単位を大幅に低減することができる。
【００２２】
なお、図１の形態例において、原料空気系統は、吸着器４３までを一系統として説明したが、原料空気系統を空気圧縮機４１の段階から、又はその吐出後の段階から二系統とし、二次圧縮機６５の後流に吸着器４３とは別個に吸着器を設けるようにしてもよい。
【００２３】
図２は、本発明を適用した窒素製造装置の第２形態例を示すものである。なお、上記図１に示した形態例における構成要素と同一の構成要素には同一符号を付して、その詳細な説明は省略する。
【００２４】
まず、原料空気は、その全量が、空気圧縮機４１で高圧塔３２の運転圧力に応じた高圧状態に圧縮された後、アフタークーラー４２，吸着器４３を経て主熱交換器４５に導入される。高圧状態の原料空気の一部は、主熱交換器４５の途中で経路７１に分岐し、膨張タービン７２で低圧塔３１の運転圧力に応じた低圧状態の圧力まで膨張するとともに寒冷を発生し、経路７３に導出される。また、主熱交換器４５から経路７４に導出した高圧状態の原料空気の一部は、経路７５に分岐して減圧弁７６で低圧状態に減圧された後、前記経路７３の低圧状態の原料空気と合流し、共に経路７７を経て低圧塔３１の下部に導入される。一方、主熱交換器４５から経路７４に導出し、経路７８に分岐した高圧状態の原料空気は、高圧状態のまま高圧塔３２の下部に導入される。
【００２５】
そして、前記同様に、低圧塔３１の上部に分離した窒素ガスを凝縮器４８で液化し、その一部を低圧塔の３１の還流液として、残部を液化窒素ポンプ３３で高圧状態に昇圧して高圧塔３２の還流液として、それぞれ用いて精留を行うことにより、高圧塔３２の上部から所定圧力の超高純度窒素ガスが得られる。
【００２６】
本形態例においても、低圧塔３１で分離した窒素ガスを液化し、得られた液化窒素を両塔の還流液として使用するので、前記同様に、製品収率の向上が図れ、原料空気量の低減による原単位の低減も図れる。
【００２７】
【実施例】
次に、図１に示す第１形態例装置，図２に示す第２形態例装置及び図３に示す従来例装置の各構成の窒素製造装置を用いて、同純度、同量の高純度窒素ガスを製造したときの製品収率や原単位を比較した結果を説明する。製品窒素ガスの採取条件は、採取量１０３０Ｎｍ3 ／ｈ、圧力７．０ｋｇ／ｃｍ2 Ｇ、酸素含有量１ｐｐｍ以下とした。
【００２８】
上記条件で製品窒素ガスを製造する際の原料空気量及びその圧力、製品収率，原単位等を計算した結果を表１に示す。
【００２９】
【表１】

Figure 0003667889
【００３０】
【発明の効果】
以上説明したように、本発明の窒素製造方法及び装置によれば、製品収率の向上や原単位の改善を図ることができ、超高純度窒素ガスを高圧で製造する際のコストを大幅に低減することができる。
【図面の簡単な説明】
【図１】 本発明を適用した窒素製造装置の一例を示す系統図である。
【図２】 窒素製造装置の他の形態例を示す系統図である。
【図３】 従来の窒素製造装置の一例を示す系統図である。
【符号の説明】
３１…低圧塔、３２…高圧塔、３３…液化窒素ポンプ、４１…空気圧縮機、４２…アフタークーラー、４３…吸着器、４５…主熱交換器、４８…凝縮器、５４…減圧弁、６１…膨張タービン、６２…減圧弁、６５…二次圧縮機、６８…減圧弁、７２…膨張タービン、７６…減圧弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nitrogen production method and apparatus, and more particularly to a method and apparatus for producing ultra-high purity nitrogen by subjecting compressed, purified, and cooled raw material air to cryogenic liquefaction rectification separation.
[0002]
[Prior art]
In recent years, demand for ultra-high purity nitrogen in semiconductor factories has increased. As an apparatus for producing this ultra-high purity nitrogen, a nitrogen producing apparatus as shown in FIG. 3 is used. This nitrogen production apparatus obtains ultra-high purity nitrogen gas by subjecting air to cryogenic liquefaction rectification separation in a rectification column, and is pressurized to a pressure higher than the pressure of product nitrogen gas by an air compressor 1. The raw material air is introduced into the adsorber 3 through the aftercooler 2 and purified by removing impurities such as moisture and carbon dioxide, and then liquefied by heat exchange with product nitrogen in the main heat exchanger 4. It is cooled to the vicinity of the point and introduced from the path 5 to the lower part of the rectifying column 6.
[0003]
The raw material air introduced into the rectification column 6 is separated into nitrogen gas at the top of the column and oxygen-enriched liquefied air at the bottom of the column by a well-known cryogenic liquefaction separation operation. The nitrogen gas at the top of the tower branches after being led out to the path 7, and the nitrogen gas branched into the path 8 is heated from the main heat exchanger 4 to the normal temperature by cooling the raw air, and then from the path 9. Collected as product nitrogen gas. Further, the nitrogen gas branched from the path 7 to the path 10 is introduced into the condenser 11 to be condensed and liquefied, and is returned to the top of the rectifying column 6 via the path 12 to become the reflux liquid of the rectifying column 6.
[0004]
The oxygen-enriched liquefied air at the bottom of the column is led out to the path 13 and depressurized to an intermediate pressure by the pressure reducing valve 14, and then branched into a path 15 and a path 16. It is introduced into the condenser 11 and becomes a cooling source for liquefying the nitrogen gas, and it evaporates and becomes oxygen-enriched air. The oxygen-enriched air led out of the condenser 11 merges with the path 16 and then branches into the path 18 and the path 19 via the path 17. The oxygen-enriched air introduced into the main heat exchanger 4 from the path 18 is heated up to an intermediate temperature and led out to the path 20 from the intermediate portion of the main heat exchanger 4 and insulated by the expansion turbine 21 to near normal pressure. It expands and generates cold.
[0005]
The oxygen-enriched air that has generated cold is branched into the path 19 and joined with the oxygen-enriched air that has been depressurized to a substantially normal pressure by the pressure reducing valve 22, and then introduced into the main heat exchanger 4 via the path 23. By cooling the air, the temperature is raised to room temperature and led out from the path 24.
[0006]
[Problems to be solved by the invention]
However, in the nitrogen production apparatus as described above, since the pressure of the product nitrogen gas depends on the pressure of the raw material air, in order to obtain a relatively high pressure nitrogen gas, the entire amount of the raw material air is compressed to a necessary pressure. Furthermore, the product yield was low and the basic unit was low because rectification separation was carried out at a high pressure in the rectification column.
[0007]
In addition, the nitrogen gas obtained by operating the rectification column at a low pressure is increased to the required pressure with a nitrogen compressor, but the product nitrogen gas is contaminated when compressed with the nitrogen compressor. Since there is a possibility, it was difficult to apply to an apparatus for producing ultra-high purity nitrogen gas.
[0008]
Accordingly, an object of the present invention is to provide a nitrogen production method and apparatus that can collect ultra-high purity nitrogen gas at a high pressure while improving product yield and unit consumption.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the nitrogen production method of the present invention introduces compressed, refined, and cooled raw material air into a rectification column, performs cryogenic liquefaction separation, and collects nitrogen in the raw material air as a product. In the method, a part of the raw material air is introduced into a low pressure column in a low pressure state and rectified, and the nitrogen gas separated at the top of the column is separated into oxygen-enriched liquefied air separated into the low pressure column bottom and the high pressure column bottom, respectively. Liquefied by a condenser as a cooling source, and the obtained liquefied nitrogen is pressurized and introduced as a reflux liquid at the top of the high-pressure column, and high-pressure raw material air is introduced at the bottom of the high-pressure column. Nitrogen gas at the top of the column obtained by rectification is collected as a product.
[0010]
In the method of the present invention, the raw material air in the high pressure state is obtained by branching a part of the raw material air whose pressure is increased to a low pressure state and increasing the pressure to a predetermined high pressure state. Further, a part of the raw material air whose pressure has been increased to a high pressure state is branched and expanded and depressurized to a predetermined low pressure state by an expansion turbine.
[0011]
Furthermore, the nitrogen production apparatus of the present invention includes a low-pressure column and a high-pressure column into which compressed, purified, and cooled raw material air is introduced, the low-pressure column includes a path for introducing the low-pressure raw material air to the lower portion of the tower, and an upper portion of the tower. A condenser for liquefying nitrogen gas by heat exchange between the rectified nitrogen gas and the oxygen-enriched liquefied air rectified and separated at the bottom of the low pressure column and the high pressure column , respectively , and one of the liquefied nitrogen liquefied by the condenser And a path for returning the remainder of the liquefied nitrogen to the top of the low pressure column as a reflux liquid and a path for increasing the pressure of the remainder of the liquefied nitrogen with a liquefied nitrogen pump as a reflux liquid to the top of the high pressure column, The above-mentioned path for introducing liquefied nitrogen from the column to the top of the tower as a reflux liquid, the path for introducing high-pressure raw material air to the bottom of the tower, and the path for deriving the rectified and separated nitrogen gas as a product at the top of the tower It is characterized by.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings. First, FIG. 1 shows a first embodiment of a nitrogen production apparatus to which the present invention is applied. This nitrogen production apparatus has a low-pressure column 31 and a high-pressure column 32 as a rectification column, and a part of the raw air is introduced into the low-pressure column 31 with a good product yield for rectification separation, and ultra-high purity liquefied nitrogen And the pressure of the ultra high purity liquefied nitrogen is increased by the liquefied nitrogen pump 33 and used as the reflux liquid of the high pressure column 32 into which the remaining raw material air is introduced. Nitrogen gas is obtained.
[0013]
First, the raw material air pressurized to a low pressure state according to the operating pressure of the low pressure tower 31 by the air compressor 41 is introduced into the adsorber 43 through the after cooler 42, and impurities such as moisture and carbon dioxide gas contained therein are removed. After being purified in this way, it is branched into the path 44 and introduced into the main heat exchanger 45, cooled to the vicinity of the liquefaction point by heat exchange with product nitrogen and the like, and introduced into the lower part of the low pressure column 31 from the path 46 in the low pressure state. Is done.
[0014]
The low-pressure raw material air introduced into the low-pressure column 31 is separated into nitrogen gas at the top of the column and oxygen-enriched liquefied air at the bottom of the column by a cryogenic liquefaction rectification separation operation. In the rectification separation in the low-pressure column 31, it is operated in a state where the relative volatility is improved by a pressure lower than that in the conventional apparatus, and the separation of oxygen and nitrogen is performed well, and the yield of nitrogen is increased. improves.
[0015]
The nitrogen gas separated to the upper part of the low-pressure column 31 is introduced into the condenser 48 from the path 47 to be condensed and liquefied, led to liquefied nitrogen and led to the path 49, and then branched into the path 50 and the path 51. The liquefied nitrogen is returned to the top of the low pressure column 31 and becomes a reflux liquid of the low pressure column 31. The liquefied nitrogen branched into the path 51 is boosted by the liquefied nitrogen pump 33 to a high pressure state corresponding to the operating pressure of the high-pressure column 32, that is, the pressure of the product nitrogen gas, and then the top of the high-pressure column 32 from the path 52. To be a reflux liquid of the high-pressure column 32.
[0016]
The oxygen-enriched liquefied air at the bottom of the low-pressure column 31 is led out to the path 53 and depressurized to an intermediate pressure by the pressure reducing valve 54, and then branched into a path 55 and a path 56 and branched into the path 55. Liquefied air is introduced into the condenser 48 and serves as a cooling source for liquefying the nitrogen gas, and it evaporates and becomes oxygen-enriched air. The oxygen-enriched air led out of the condenser 48 merges with the path 56 and then branches into a path 58 and a path 59 via the path 57. The oxygen-enriched air introduced into the main heat exchanger 45 from the path 58 is heated to an intermediate temperature and led out to the path 60 from the intermediate portion of the main heat exchanger 45, and is insulated by the expansion turbine 61 to near normal pressure. It expands and generates cold.
[0017]
The oxygen-enriched air that has generated cold is branched into the path 59 and joined with the oxygen-enriched air that has been decompressed to a substantially normal pressure by the pressure reducing valve 62, and is then introduced into the main heat exchanger 45 via the path 63. The temperature is raised to room temperature by cooling the air, and the air is led out from the path 64.
[0018]
On the other hand, after the adsorber 43 is led out and branched into the path 64, the low-pressure raw material air is boosted to a high-pressure state corresponding to the pressure of the product nitrogen gas by the secondary compressor 65 and then the main heat exchanger 45. And is introduced into the lower part of the high-pressure tower 32 through the path 66. In the high-pressure column 32, rectification is performed by the high-pressure raw material air introduced in the lower portion and the high-pressure liquefied nitrogen introduced from the passage 52, and ultra-high purity nitrogen gas is separated in the upper portion of the column. Oxygen-enriched liquefied air is separated at the bottom of the column.
[0019]
The oxygen-enriched liquefied air led out from the bottom of the column to the path 67 is decompressed by the pressure reducing valve 68, and then merges with the oxygen-enriched liquefied air led out from the low-pressure column 31 to the path 53, and the condenser 48, the expansion turbine 61, it is derived | led-out from the path | route 64 through the main heat exchanger 45 grade | etc.,.
[0020]
The ultra-high purity nitrogen gas led out from the upper part of the high-pressure tower 32 to the path 69 is recovered from the path 70 as product nitrogen gas after the temperature is recovered by the main heat exchanger 45.
[0021]
Thus, by liquefying the nitrogen gas separated in the low-pressure tower 31 having a low pressure and excellent product yield to obtain a reflux liquid, the amount of the reflux liquid can be increased as compared with the conventional method. This makes it possible to reduce the product yield. Furthermore, since the total amount of raw material air is not increased to a high-pressure state higher than the pressure of product nitrogen gas, the required power of the air compressor can be reduced, especially when the product nitrogen gas pressure is high, the product yield is improved. By the synergistic effect, the basic unit can be greatly reduced.
[0022]
In the embodiment shown in FIG. 1, the raw material air system has been described as one system up to the adsorber 43, but the raw material air system is divided into two systems from the stage of the air compressor 41 or from the stage after the discharge. An adsorber may be provided in the downstream of the next compressor 65 separately from the adsorber 43.
[0023]
FIG. 2 shows a second embodiment of the nitrogen production apparatus to which the present invention is applied. In addition, the same code | symbol is attached | subjected to the component same as the component in the form example shown in the said FIG. 1, and the detailed description is abbreviate | omitted.
[0024]
First, the entire amount of the raw air is compressed by the air compressor 41 to a high pressure state corresponding to the operating pressure of the high pressure tower 32, and then introduced into the main heat exchanger 45 through the after cooler 42 and the adsorber 43. . A portion of the high-pressure raw material air branches into the path 71 in the middle of the main heat exchanger 45, expands to a low-pressure pressure corresponding to the operating pressure of the low-pressure tower 31 in the expansion turbine 72, and generates cold. The route 73 is derived. Further, part of the high-pressure raw material air led out from the main heat exchanger 45 to the path 74 is branched into the path 75 and decompressed to a low pressure state by the pressure reducing valve 76, and then the low-pressure raw material air in the path 73. And are introduced into the lower part of the low-pressure column 31 via the path 77. On the other hand, the high-pressure raw material air led out from the main heat exchanger 45 to the path 74 and branched to the path 78 is introduced into the lower portion of the high-pressure tower 32 while maintaining the high-pressure state.
[0025]
Similarly to the above, the nitrogen gas separated in the upper part of the low-pressure column 31 is liquefied by the condenser 48, a part thereof is used as the reflux liquid of the low-pressure column 31, and the remainder is increased to a high-pressure state by the liquefied nitrogen pump 33. By performing rectification using each as the reflux liquid of the high-pressure column 32, ultra-high purity nitrogen gas having a predetermined pressure can be obtained from the upper part of the high-pressure column 32.
[0026]
Also in this embodiment, since the nitrogen gas separated in the low pressure column 31 is liquefied and the obtained liquefied nitrogen is used as the reflux liquid of both columns, the product yield can be improved and the amount of raw material air can be increased as described above. The basic unit can be reduced by the reduction.
[0027]
【Example】
Next, using the first embodiment apparatus shown in FIG. 1, the second embodiment apparatus shown in FIG. 2, and the conventional apparatus shown in FIG. The result of comparing the product yield and the basic unit when producing gas will be described. The sampling conditions for the product nitrogen gas were a sampling amount of 1030 Nm 3 / h, a pressure of 7.0 kg / cm 2 G, and an oxygen content of 1 ppm or less.
[0028]
Table 1 shows the results of calculating the amount of raw material air and its pressure, product yield, basic unit, etc. when producing product nitrogen gas under the above conditions.
[0029]
[Table 1]
Figure 0003667889
[0030]
【The invention's effect】
As described above, according to the nitrogen production method and apparatus of the present invention, it is possible to improve the product yield and the basic unit, greatly increasing the cost when producing ultra-high purity nitrogen gas at high pressure. Can be reduced.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an example of a nitrogen production apparatus to which the present invention is applied.
FIG. 2 is a system diagram showing another example of a nitrogen production apparatus.
FIG. 3 is a system diagram showing an example of a conventional nitrogen production apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 31 ... Low pressure column, 32 ... High pressure column, 33 ... Liquid nitrogen pump, 41 ... Air compressor, 42 ... After cooler, 43 ... Adsorber, 45 ... Main heat exchanger, 48 ... Condenser, 54 ... Pressure reducing valve, 61 ... expansion turbine, 62 ... pressure reducing valve, 65 ... secondary compressor, 68 ... pressure reducing valve, 72 ... expansion turbine, 76 ... pressure reducing valve

Claims (4)

圧縮，精製，冷却した原料空気を精留塔に導入して深冷液化精留分離を行い、原料空気中の窒素を製品として採取する方法において、原料空気の一部を低圧状態で低圧塔に導入して精留し、その塔頂部に分離した窒素ガスを、前記低圧塔底部及び高圧塔底部にそれぞれ分離した酸素富化液化空気を冷却源として凝縮器で液化し、得られた液化窒素を昇圧して高圧塔の頂部に還流液として導入するとともに、該高圧塔の底部に高圧状態の原料空気を導入し、該高圧塔での精留により得られた塔頂部の窒素ガスを製品として採取することを特徴とする窒素製造方法。In a method in which compressed, refined, and cooled raw material air is introduced into a rectifying column to perform cryogenic liquefaction separation, and nitrogen in the raw material air is collected as a product. Introduced and rectified, the nitrogen gas separated at the top of the tower was liquefied with a condenser using the oxygen-enriched liquefied air separated at the bottom of the low pressure tower and the bottom of the high pressure tower as a cooling source , and the obtained liquefied nitrogen was The pressure is increased and introduced into the top of the high-pressure column as a reflux liquid, and high-pressure raw material air is introduced into the bottom of the high-pressure column, and nitrogen gas at the top of the column obtained by rectification in the high-pressure column is collected as a product. A method for producing nitrogen, comprising: 前記高圧状態の原料空気は、低圧状態に昇圧した原料空気の一部を分岐して昇圧したものであることを特徴とする請求項１記載の窒素製造方法。  2. The method for producing nitrogen according to claim 1, wherein the high-pressure source air is obtained by branching and increasing a part of the source air whose pressure has been increased to a low-pressure state. 前記低圧状態の原料空気は、高圧状態に昇圧した原料空気の一部を分岐して膨張タービンで膨張降圧したものであることを特徴とする請求項１記載の窒素製造方法。  2. The method for producing nitrogen according to claim 1, wherein the raw material air in a low pressure state is obtained by branching a part of the raw material air whose pressure has been increased to a high pressure state and expanding and depressurizing it with an expansion turbine. 圧縮，精製，冷却した原料空気が導入される低圧塔及び高圧塔を備え、前記低圧塔は、低圧原料空気を塔下部に導入する経路と、塔上部に精留分離した窒素ガスと前記低圧塔底部及び高圧塔底部にそれぞれ精留分離した酸素富化液化空気とを熱交換させて窒素ガスを液化する凝縮器と、凝縮器で液化した液化窒素の一部を還流液として低圧塔頂部に戻す経路と、該液化窒素の残部を液化窒素ポンプで昇圧して前記高圧塔の頂部に還流液として導入する経路とを備え、前記高圧塔は、前記凝縮器からの液化窒素を還流液として塔頂部に導入する前記経路と、高圧原料空気を塔下部に導入する経路と、塔頂部に精留分離した窒素ガスを製品として導出する経路とを備えていることを特徴とする窒素製造装置。A low-pressure column and a high-pressure column into which compressed, refined, and cooled raw material air is introduced. The low-pressure column includes a path for introducing the low-pressure raw material air into the lower portion of the tower, rectified and separated nitrogen gas at the upper portion of the tower, and the low-pressure column. a condenser and oxygen-enriched liquefied air in the bottom and the high pressure column bottom was rectified separated respectively by heat exchange to liquefy nitrogen gas is returned to the low pressure column top part of the liquid nitrogen which is liquefied in the condenser as reflux A path and a path for boosting the remainder of the liquefied nitrogen with a liquefied nitrogen pump and introducing it into the top of the high-pressure column as a reflux liquid, the high-pressure tower using the liquefied nitrogen from the condenser as the reflux liquid A nitrogen production apparatus, comprising: a path for introducing the high-pressure raw material air into the lower part of the tower; a path for introducing rectified and separated nitrogen gas as a product at the top of the tower;
JP21621196A 1996-08-16 1996-08-16 Nitrogen production method and apparatus Expired - Fee Related JP3667889B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP21621196A JP3667889B2 (en) 1996-08-16 1996-08-16 Nitrogen production method and apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP21621196A JP3667889B2 (en) 1996-08-16 1996-08-16 Nitrogen production method and apparatus

Publications (2)

Publication Number Publication Date
JPH1062062A JPH1062062A (en) 1998-03-06
JP3667889B2 true JP3667889B2 (en) 2005-07-06

Family

ID=16685024

Family Applications (1)

Application Number Title Priority Date Filing Date
JP21621196A Expired - Fee Related JP3667889B2 (en) 1996-08-16 1996-08-16 Nitrogen production method and apparatus

Country Status (1)

Country Link
JP (1) JP3667889B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6397631B1 (en) 2001-06-12 2002-06-04 Air Products And Chemicals, Inc. Air separation process

Also Published As

Publication number Publication date
JPH1062062A (en) 1998-03-06

Similar Documents

Publication Publication Date Title
JP2865274B2 (en) Cryogenic distillation of air for the simultaneous production of oxygen and nitrogen as gaseous and / or liquid products
TWI525298B (en) Air liquefaction separation method and device
JPH07270066A (en) Cryogenic rectifying system for manufacturing pressure-elevated nitrogen
EP2963368B1 (en) Air separation method and air separation apparatus
US4192662A (en) Process for liquefying and rectifying air
EP0425738A1 (en) Process for the production of high pressure nitrogen with split reboil-condensing duty
JPH06207775A (en) Low-temperature air separating method for manufacturing nitrogen having no carbon monoxide
CN106595221A (en) Oxygen production system and oxygen production method
MXPA97008225A (en) A cryogenic cycle of three columns for the production of impure oxygen and nitrogen p
JP3190016B2 (en) Low-temperature distillation method for feed air producing high-pressure nitrogen
JP2007147113A (en) Nitrogen manufacturing method and device
JP4401999B2 (en) Air separation method and air separation device
JPH07151458A (en) Method and equipment for preparing gaseous oxygen and/or nitrogen under pressure
EP0754923A2 (en) Ultra-high purity nitrogen generating method and unit
JP5032407B2 (en) Nitrogen production method and apparatus
JP3667889B2 (en) Nitrogen production method and apparatus
JPH06249574A (en) Method and equipment for manufacturing oxygen and/or nitrogen under pressure
JPH07151459A (en) Method and equipment for preparing at least one gas from airunder pressure
JP4447501B2 (en) Air liquefaction separation method and apparatus
JP3738213B2 (en) Nitrogen production method and apparatus
JP3748677B2 (en) Method and apparatus for producing low purity oxygen
JP4177507B2 (en) Method and apparatus for producing low purity oxygen
JP2920392B2 (en) Supercooling method of liquefied nitrogen in air liquefaction separator
JP3737612B2 (en) Method and apparatus for producing low purity oxygen
JP2001336876A (en) Method and system for producing nitrogen

Legal Events

Date Code Title Description
A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20041021

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20041102

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20041221

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20050315

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20050407

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20080415

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20090415

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20090415

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100415

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100415

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100415

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110415

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110415

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120415

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130415

Year of fee payment: 8

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130415

Year of fee payment: 8

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140415

Year of fee payment: 9

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

LAPS Cancellation because of no payment of annual fees