JP2773858B2 - Method and apparatus for separating air - Google Patents

Method and apparatus for separating air

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Publication number
JP2773858B2
JP2773858B2 JP61233122A JP23312286A JP2773858B2 JP 2773858 B2 JP2773858 B2 JP 2773858B2 JP 61233122 A JP61233122 A JP 61233122A JP 23312286 A JP23312286 A JP 23312286A JP 2773858 B2 JP2773858 B2 JP 2773858B2
Authority
JP
Japan
Prior art keywords
nitrogen
carbon dioxide
stream
air
water vapor
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 - Lifetime
Application number
JP61233122A
Other languages
Japanese (ja)
Other versions
JPS62142985A (en
Inventor
マイケル・アーネスト・ガーレット
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.)
BOC Group Ltd
Original Assignee
BOC Group Ltd
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Filing date
Publication date
Application filed by BOC Group Ltd filed Critical BOC Group Ltd
Publication of JPS62142985A publication Critical patent/JPS62142985A/en
Application granted granted Critical
Publication of JP2773858B2 publication Critical patent/JP2773858B2/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
    • 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
    • F25J3/04636—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 hybrid air separation unit, e.g. combined process by cryogenic separation and non-cryogenic separation techniques
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—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
    • 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
    • F25J2205/24—Processes or apparatus using other separation and/or other processing means using regenerators, cold accumulators or reversible heat exchangers
    • 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
    • F25J2205/80—Processes or apparatus using other separation and/or other processing means using membrane, i.e. including a permeation step
    • 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
    • F25J2230/42—Processes or apparatus involving steps for increasing the pressure of gaseous 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/12—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being nitrogen

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Description

【発明の詳細な説明】 産業上の利用分野 本発明は空気分離に係るものである。特に、本発明は
少くとも１つの逆流熱交換器を使用して低温で空気を分
離する方法と装置とに係るものである。 従来の技術 低温分離装置は製品として窒素、酸素およびアルゴン
の１種またはそれ以上を生成する産業で良く知られ広く
使用されている。極低温空気分離装置の１例が英国特許
第1,258,568号に記載されている。そのような装置で
は、空気を清浄にするかまたは選択した極低温に冷却す
る。次いで、ほぼ純粋の窒素か酸素、この英国特許の装
置の例ではアルゴンを生成するため空気を分別する。二
酸化炭素と水蒸気とを除去するため空気を清浄にするに
は主に３種類の方法がある。１つの方法では、空気清浄
化の一部を少くとも１つの逆流熱交換器か熱交換器で行
う。逆流熱交換器か熱交換器では、空気を漸次に冷却し
水蒸気の如き不純物が冷却中の空気に接触する熱交換器
の表面に凍結粒子として析出する。 逆流熱交換器または熱交換器には窒素流（ある程度酸
素不純物を含んでいる）用の通路が設けられており、こ
の窒素流は空気流と向流して流れ凍結不純物を蒸発させ
るため使用する。空気が通過する熱交換器の通路内にお
ける不純物のレベルがある選択したレベルに達すると、
空気通路を窒素流通路に切換えてこの不純物を取り除
く。逆流熱交換器または熱交換器を通過した後、窒素流
を大気に排出する。現在使用してない別の方法では複数
の再生器を使用する。冷却される空気を１つの再生器を
通し窒素の廃流を別の再生器をある時間通し、その後両
方の流れを切換え、空気は戻り製品流により予め冷却さ
れた再生器を通して流れる。再生器には「冷たく」貯蔵
できるようにする適当なパッキングが設けてある。二酸
化炭素と水蒸気とを冷却されている空気から固体として
析出させ次いで窒素流で再昇華させる。 第３の方法では、温度変動式ふるい洗浄ユニットを使
用する。二酸化炭素と水蒸気とをこのふるいの吸収剤の
少くとも１つの床における液状水滴から遊離した圧縮空
気から吸収し、他方残りの床は再生される。選択した時
間の経過後、床を切り換える。例は典型的な窒素流の少
くとも一部分を加熱しそれを分子ふるい吸収剤を通過さ
せて行いそれにより水蒸気、二酸化炭素およびその他の
吸収された不純物とを吸収する。 従って、これらの方法のいずれにおいても、典型的に
は容量にして１％程度の酸素を含み空気清浄ユニットか
らの流れにより取り除かれる不純物を担持した窒素廃流
が生成される。典型的には、窒素廃流は空気分離器内で
製品として生成された窒素を容量にして35％程度含んで
いる。数年来窒素の需要が増大し、従って、そのような
空気分離器からの窒素の吸率を増す必要がある。 従って、本発明の法と装置とはその最も広範な面にお
いて不純物担持流を清浄にする。 従って、本発明は水蒸気と二酸化炭素とを抽出手段で
除去する段階と、空気を低温に冷却しそれを分別して酸
素製品および窒素製品ならびに酸素の濃度が窒素製品の
O2濃度より高い窒素流を生成する段階と、窒素流の少く
とも一部分を使用して水蒸気と二酸化炭素とを抽出手段
からパージする段階と、その結果による不純物担持窒素
の少くとも一部分を清浄にする段階とを含む空気分離方
法を提供する。 本発明はまた空気から水蒸気と二酸化炭素とを抽出す
る手段と、空気を極低温に冷却する手段と、酸素および
窒素ならびに酸素の濃度が窒素製品のO2濃度より高い窒
素流を生成する少くとも１つの分別カラムと、窒素流の
少くとも一部分を抽出手段を通過させこの流れから水蒸
気と二酸化炭素とを排出する手段と、その結果による不
純物担持窒素流を清浄にする手段とを含む空気分離装置
を提供する。 抽出手段は少くとも１つの逆流熱交換器で構成するこ
とが好ましく、この熱交換器では空気の少くとも一部分
を冷却し、従って、水蒸気と二酸化炭素とを固体として
沈澱させ、次いで窒素流により昇華させる。 不純物担持窒素流は膜分離により清浄にすることが好
ましい。酸素、水蒸気および二酸化炭素を窒素から分離
できる膜は既知で市販されている。清浄にされた廃流に
所望の酸素濃度如何により１つまたはそれ以上の数の膜
分離段を使用できる。一般には洗浄化以前に窒素流は容
量にして１％かそれ以下の酸素を含んでいることが好ま
しい。 あるいはまた圧力振動吸収を利用して窒素流を清浄に
することもできる。 不純物担持窒素流は膜分離に先立ち望ましいのは10な
いし30気圧に圧縮することが好ましい。コンプレッサま
たはそれに関係した後段冷却器においてこのように凝縮
した水は窒素流に入る以前に膜分離手段により流出でき
る。清浄にされた窒素流が不透過流であるので、この流
れは膜分離器では比較的に僅かしか圧力が降下しない。
従って、コンプレッサ（または別のコンプレッサ）を駆
動するため典型的に使用される膨張タービン内で圧縮手
段が行った圧縮の一部分を元に戻すことができる。もし
所望ならば、清浄にされた窒素流の加工膨張による冷凍
作用を空気分離機の熱交換系統に関係した液化装置に利
用できる。 もし所望ならば、不純物担持窒素流を清浄にする手段
は既存の空気分離器に再び装備できる。 不純物担持窒素内の水と二酸化炭素の濃度はそのよう
な逆転熱交換器の回生にわたり一定でない。水と二酸化
炭素との濃度が平均以下である場合運転中膜分離器の透
過流に窒素が入る速度を押さえるため、窒素を膜分離器
に供給する圧力を変えることができる。あるいはまた、
不純物担持窒素流を膜分離器に供給する速度は典型的に
は逆流熱交換器または熱交換器の出口の下手順にそのよ
うな流れの一部分を放出することにより変えることがで
きる。それに代えてかまたはそれに加えて、不純物担持
窒素流は清浄化手段の上手側で緩衝容器に流れることが
できる。 以下に本発明を空気分離装置の一部を形成する逆流熱
交換器に流れ連通関係にした清浄化ユニットを線図で示
す添付図面を参照して例示的に説明する。 実施例 図面を参照すると、分離される空気流は、典型的には
容量で１％の酸素不純物を含む窒素流および比較的に純
粋な窒素製品流のそれぞれ用の通路4,6,8を有する逆転
熱交換器２が示してある。逆転熱交換器２は通路4,6を
切換える手段（図示せず）を有している。そのような手
段は全く従来技術のものであり、従って、詳細には説明
しない。不純物担持チッ素通路は濃縮水用のドレン14を
装備した後段冷却器を有するコンプレッサ10の入口に連
通している。コンプレッサの出口側は後段冷却器12を介
して膜分離器18に連通し、この分離器は非不透過ガス用
の出口20と透過ガス用の出口22とを有している。出口22
は典型的にはコンプレッサ10を駆動するため使用する膨
張タービン24の入口に連通している。 運転すると、逆流熱交換器２を通過する不純のチッ素
流が空気流により先に沈澱した固体不純物を蒸発させ
る。固体不純物は固体の二酸化炭素と水とから成る。そ
の結果による不純物担持チッ素流はコンプレッサ10内で
10ないし30絶対大気圧に圧縮され後段冷却器12でその結
果凝縮した水をドレン14を通り排出して膜分離器18に入
る。分離器18に入る不純物担持窒素中の酸素不純物の少
なくとも90％、窒素中のほぼ全部の水蒸気と二酸化炭素
不純物及び１部の窒素を含む透過流が生成され出口22を
通り装置を出る。ほぼ純粋の窒素から成る残りのガスが
出口20を通り分離器を出て膨張タービン24内で低い圧力
に膨張する。ガスは次いでパイプライン（図示せず）を
経て膨張タービン24の出口からそれを使用する装置（た
とえば非反応雰囲気を生じる）に生成物として送られ
る。もし窒素が高圧であることが必要であれば、たとえ
ば、窒素が液化されるシリンダを満たす必要のある場合
には、膨張タービン24は第１図の装置から省略できる。 装置は更にまた吸収器すなわち膜分離器18の上手側か
ら下手側で窒素流からこん跡量の炭化水素を取り除く吸
収器を含むことができる。 本発明の１つの例では、逆流熱交換器２は英国特許第
1,258,568号に記載しまた図面に示した如き逆流熱交換
器の如くにして使用することもできる。従って、膜分離
器とそれに関係したコンプレッサと膨張タービンとは、
もし所望ならば、前記英国特許の図面に示した如く空気
分離装置に再び装備できる。前記英国特許にはアルゴン
を分離するため側柱付きの単一の精留柱を使用する空気
分離装置が記載してあるが、本発明の方法と装置とは２
重の精留柱（アルゴン側柱付きかそれのない）空気分離
装置かまたは酸素および窒素製品のみを生成する単一柱
を使用する空気分離装置と併用できることは理解する必
要がある。Description: FIELD OF THE INVENTION The present invention relates to air separation. In particular, the present invention relates to a method and apparatus for separating air at low temperatures using at least one countercurrent heat exchanger. BACKGROUND OF THE INVENTION Cryogenic separation equipment is well known and widely used in the industry for producing one or more of nitrogen, oxygen and argon as products. One example of a cryogenic air separation unit is described in GB 1,258,568. In such devices, the air is cleaned or cooled to a selected cryogenic temperature. The air is then fractionated to produce nearly pure nitrogen or oxygen, in the example of the device of this patent, argon. There are mainly three types of methods for purifying air to remove carbon dioxide and water vapor. In one method, part of the air cleaning is performed in at least one backflow heat exchanger or heat exchanger. In a backflow heat exchanger or heat exchanger, the air is gradually cooled and impurities, such as water vapor, precipitate as frozen particles on the surface of the heat exchanger in contact with the cooling air. The backflow heat exchanger or heat exchanger is provided with a passageway for a nitrogen stream (containing some oxygen impurities) which is used to evaporate the frozen impurities which flows countercurrently to the air stream. When the level of impurities in the passage of the heat exchanger through which air passes reaches a certain selected level,
The air passage is switched to a nitrogen flow passage to remove this impurity. After passing through a backflow heat exchanger or heat exchanger, the nitrogen stream is vented to the atmosphere. Another method not currently used uses multiple regenerators. The air to be cooled is passed through one regenerator and the waste stream of nitrogen is passed through another regenerator for a period of time, after which both streams are switched, and the air flows back through the precooled regenerator by the product stream. The regenerator is provided with suitable packing to allow "cold" storage. Carbon dioxide and water vapor are precipitated as solids from the cooled air and then resublimated with a stream of nitrogen. In the third method, a temperature fluctuation type sieve cleaning unit is used. Carbon dioxide and water vapor are absorbed from the compressed air liberated from the liquid droplets in at least one bed of the absorbent of the sieve, while the remaining bed is regenerated. After the selected time has elapsed, the floor is switched. The example heats at least a portion of a typical nitrogen stream and passes it through a molecular sieve absorbent, thereby absorbing water vapor, carbon dioxide and other absorbed impurities. Thus, in either of these methods, a nitrogen waste stream is generated which typically contains on the order of 1% oxygen and carries impurities which are removed by the stream from the air cleaning unit. Typically, the nitrogen waste stream contains as much as 35% by volume of nitrogen produced as product in the air separator. Over the years, the demand for nitrogen has increased, and there is therefore a need to increase the absorption of nitrogen from such air separators. Thus, the method and apparatus of the present invention cleans the impurity carrying stream in its broadest aspects. Therefore, the present invention provides a step of removing water vapor and carbon dioxide by an extraction means, and a step of cooling the air to a low temperature and separating the same so that the oxygen product and the nitrogen product and the oxygen concentration of the nitrogen product are reduced.
Generating a O 2 is higher than the concentration of nitrogen stream, at least a nitrogen stream using a portion a step of purging the extraction means and a water vapor and carbon dioxide, to clean at least a portion of the impurity-bearing nitrogen by a result Air separation method. The present invention also comprises means for extracting the water vapor and carbon dioxide from the air, and means for cooling the air to a cryogenic temperature, at a minimum concentration of oxygen and nitrogen as well as oxygen to produce a high nitrogen flow than the O 2 concentration of the nitrogen product An air separation device comprising: a fractionation column; means for passing at least a portion of the nitrogen stream through extraction means to remove water vapor and carbon dioxide from the stream; and means for purifying the resulting nitrogen stream carrying impurities. I will provide a. The extraction means preferably comprises at least one countercurrent heat exchanger, which cools at least a part of the air, thus precipitating water vapor and carbon dioxide as solids and then sublimating with a stream of nitrogen. Let it. Preferably, the nitrogen stream carrying the impurities is cleaned by membrane separation. Membranes that can separate oxygen, water vapor and carbon dioxide from nitrogen are known and commercially available. One or more membrane separation stages can be used in the cleaned waste stream, depending on the desired oxygen concentration. Generally, prior to scrubbing, the nitrogen stream preferably contains 1% or less oxygen by volume. Alternatively, the nitrogen flow can be cleaned using pressure vibration absorption. Prior to membrane separation, the impurity-bearing nitrogen stream is preferably compressed to 10 to 30 atmospheres. The water thus condensed in the compressor or associated post-cooler can be discharged by means of the membrane separation before entering the nitrogen stream. Since the nitrogen stream that has been cleaned is an impermeable stream, this stream will have relatively little pressure drop in the membrane separator.
Thus, a portion of the compression performed by the compression means in the expansion turbine typically used to drive the compressor (or another compressor) can be undone. If desired, the refrigeration effect of the working expansion of the cleaned nitrogen stream can be utilized in a liquefier associated with the heat exchange system of the air separator. If desired, the means for cleaning the impurity-bearing nitrogen stream can be re-equipped with existing air separators. The concentrations of water and carbon dioxide in the impurity-carrying nitrogen are not constant over the regeneration of such a reversing heat exchanger. When the concentration of water and carbon dioxide is below average, the pressure at which nitrogen is supplied to the membrane separator during operation can be varied to reduce the rate at which nitrogen enters the permeate stream of the membrane separator. Alternatively,
The rate at which the impurity-carrying nitrogen stream is fed to the membrane separator can be varied, typically by discharging a portion of such a stream to a backflow heat exchanger or a procedure below the outlet of the heat exchanger. Alternatively or additionally, the nitrogen stream carrying the impurities can flow to the buffer vessel upstream of the cleaning means. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying drawing, which shows diagrammatically a cleaning unit in flow communication with a backflow heat exchanger forming part of an air separation unit. EXAMPLES Referring to the drawings, the air stream to be separated has passages 4, 6, 8 for a nitrogen stream, typically containing 1% by volume of oxygen impurities, and a relatively pure nitrogen product stream, respectively. A reversing heat exchanger 2 is shown. The reversing heat exchanger 2 has means (not shown) for switching the passages 4 and 6. Such means are entirely prior art and therefore will not be described in detail. The impurity-carrying nitrogen passage communicates with the inlet of a compressor 10 having a post-stage cooler equipped with a drain 14 for concentrated water. The outlet side of the compressor communicates with a membrane separator 18 via a post-cooler 12, which has an outlet 20 for non-impervious gas and an outlet 22 for permeate gas. Exit 22
Is typically in communication with the inlet of an expansion turbine 24 used to drive the compressor 10. In operation, the impure nitrogen stream passing through the backflow heat exchanger 2 evaporates the solid impurities previously precipitated by the air stream. Solid impurities consist of solid carbon dioxide and water. The resulting impurity-carrying nitrogen flow in the compressor 10
Water that has been compressed to 10-30 absolute atmospheric pressure and condensed as a result in post-cooler 12 passes through drain 14 and enters membrane separator 18. A permeate stream containing at least 90% of the oxygen impurities in the nitrogen bearing impurities entering the separator 18 and substantially all of the water vapor and carbon dioxide impurities in the nitrogen and a portion of the nitrogen is generated and exits the apparatus through outlet 22. The remaining gas, consisting essentially of nitrogen, exits the separator through outlet 20 and expands to a lower pressure in expansion turbine 24. The gas is then sent as a product from the outlet of expansion turbine 24 via a pipeline (not shown) to the equipment using it (eg, to create a non-reactive atmosphere). If the nitrogen needs to be at a high pressure, for example if it is necessary to fill a cylinder in which the nitrogen is liquefied, the expansion turbine 24 can be omitted from the apparatus of FIG. The apparatus may further include an absorber or absorber that removes traces of hydrocarbons from the nitrogen stream from the upper side to the lower side of the membrane separator 18. In one example of the invention, the backflow heat exchanger 2 is a British patent.
It can also be used as a countercurrent heat exchanger as described in US Pat. No. 1,258,568 and shown in the drawings. Therefore, the membrane separator and its associated compressor and expansion turbine are:
If desired, the air separation unit can be re-equipped as shown in the drawing of the aforementioned British patent. Although the British patent describes an air separation apparatus that uses a single rectification column with side columns to separate argon, the method and apparatus of the present invention are two separate.
It should be understood that it can be used with a heavy rectification column (with or without an argon side column) air separation unit or an air separation unit using a single column that produces only oxygen and nitrogen products.

【図面の簡単な説明】 添付図面は本発明に係る空気分離装置の線図である。 ２……抽出手段、８……通過手段 10……コンプレッサ、12……冷却手段 18……分離器、24……タービン[Brief description of the drawings] The accompanying drawings are diagrams of an air separation device according to the present invention. 2 ... extracting means, 8 ... passing means 10 ... Compressor, 12 ... Cooling means 18… Separator, 24… Turbine

Claims (1)

(57)【特許請求の範囲】 １．抽出手段で空気から水蒸気と二酸化炭素とを抽出
し、その空気を極低温まで冷却し、空気を分別して酸素
製品および窒索製品ならびに酸素濃度が窒素製品の酸素
濃度より高い窒素流を生成し、その窒素流の少なくとも
一部分を使用して抽出手段からの水蒸気と二酸化炭素と
をパージし、得られた二酸化炭素及び水蒸気不純物を持
った窒素流の少なくとも一部分を精製して、そこから水
蒸気および二酸化炭素不純物を除去し、そしてその精製
した窒素から追加の窒素生成物を取出すことを特徴とす
る空気を分離する方法。 ２．抽出手段が少なくとも１個の逆流熱交換器で構成さ
れておりその熱交換器で空気冷却の少なくとも一部分が
行われ、そのため水蒸気と二酸化炭素とが固体として析
出され、そしてその後窒素流により昇華せしめられる特
許請求の範囲第１項の方法。 ３．二酸化炭素および水蒸気不純物を持った窒素流を膜
分離により精製される特許請求の範囲第１項または第２
頃の方法。 ４．二酸化炭素および水蒸気不純物を持った窒素流を膜
分離部の上流側で圧縮する特許請求の範囲第３項の方
法。 ５．二酸化炭素および水蒸気不純物を持った窒素流を10
〜30気圧の範囲の圧力に圧縮する特許請求の範囲第４項
の方法。 ６．精製した空気流を膜分離の下手側で加工膨張する特
許請求の範囲第４頃または第５頃の方法。 ７．二酸化炭素および水蒸気不純物を持った窒素流を圧
力振動吸収により精製する特許請求の範囲第１頃または
第２頃の方法。 ８．二酸化炭素および水蒸気不純物を持った窒素流が１
容量％又はそれ以下の酸素を含んでいる前記各項のいず
れか１つの方法。 ９．空気から水蒸気と二酸化炭素とを抽出する手段と、
空気を極低温に冷却する手段と、酸素および窒素製品な
らびに酸素濃度が窒素製品の酸素濃度より高い窒素流を
生成する少なくとも１つの分別カラムと、その窒素流の
少なくとも一部分を抽出手段を通過させて抽出手段から
水蒸気と二酸化炭素とをパージする手段と、その得られ
た二酸化炭素および水蒸気不純物を持った窒素流の少な
くとも一部分を精製してそこから水蒸気及び二酸化炭素
不純物を除去する手段とその精製した窒素から追加の窒
素精製物を取り出す手段を含んでいることを特徴とする
空気を分離する装置。 １０．抽出手段が内部で空気冷却の少なくとも一部分を
行う少なくとも１つの逆流交換器により構成してある特
許請求の範囲第９頃の装置。 １１．精製手段が膜分離器を備えている特許請求の範囲
第10項の装置。 １２．更にまた膜分離器の上流側において不純物担持窒
素流用のコンプレッサを含んでいる特許請求の範囲第11
頃の装置。 １３．更にまた精製した窒素流を加工膨張する膨張ター
ビンを含んでいる特許請求の範囲第12頃の装置。 １４．精製手段が圧縮振動吸収により作用する特許請求
の範囲第10項の装置。(57) [Claims] Extracting water vapor and carbon dioxide from the air by the extraction means, cooling the air to cryogenic temperatures, separating the air to produce a nitrogen stream in which the oxygen and nitrogen products and the oxygen concentration are higher than the oxygen concentration of the nitrogen product, At least a portion of the nitrogen stream is used to purge steam and carbon dioxide from the extraction means, and the resulting carbon dioxide and at least a portion of the nitrogen stream with steam impurities is purified, from which steam and carbon dioxide are removed. A method for separating air, comprising removing impurities and removing additional nitrogen products from the purified nitrogen. 2. The extraction means consist of at least one backflow heat exchanger in which at least part of the air cooling takes place, so that water vapor and carbon dioxide are deposited as solids and are subsequently sublimated by a stream of nitrogen. The method of claim 1. 3. 3. The method according to claim 1, wherein the nitrogen stream having carbon dioxide and water vapor impurities is purified by membrane separation.
Around the time. 4. 4. The method of claim 3 wherein the nitrogen stream with carbon dioxide and water vapor impurities is compressed upstream of the membrane separation. 5. 10 streams of nitrogen with carbon dioxide and water vapor impurities
5. The method of claim 4 wherein the compression is to a pressure in the range of ~ 30 atmospheres. 6. The method according to claims 4 or 5, wherein the purified air stream is processed and expanded on the lower side of the membrane separation. 7. A method according to claim 1 or claim 2 wherein the nitrogen stream with carbon dioxide and water vapor impurities is purified by pressure vibration absorption. 8. One nitrogen stream with carbon dioxide and water vapor impurities
The method of any one of the preceding clauses wherein the method comprises% by volume or less oxygen. 9. Means for extracting water vapor and carbon dioxide from air;
Means for cooling the air to cryogenic temperature, at least one fractionation column for producing a stream of oxygen and nitrogen and a nitrogen stream wherein the oxygen concentration is higher than the oxygen concentration of the nitrogen product, and passing at least a portion of the stream of nitrogen through the extraction means Means for purging water vapor and carbon dioxide from the extraction means, means for purifying at least a portion of the resulting nitrogen stream having carbon dioxide and water vapor impurities and removing water vapor and carbon dioxide impurities therefrom, and the purified An apparatus for separating air, comprising means for removing additional nitrogen product from nitrogen. 10. Apparatus according to claim 9 wherein the extraction means comprises at least one backflow exchanger within which at least part of the air cooling is performed. 11. 11. The apparatus according to claim 10, wherein the purification means comprises a membrane separator. 12. Claim 11 further comprising a compressor for the nitrogen stream carrying the impurities upstream of the membrane separator.
Around the time. 13. 13. The apparatus of claim 12, further comprising an expansion turbine for processing and expanding the purified nitrogen stream. 14． 11. The apparatus according to claim 10, wherein the refining means operates by compressive vibration absorption.
JP61233122A 1985-09-30 1986-09-30 Method and apparatus for separating air Expired - Lifetime JP2773858B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8524080 1985-09-30
GB8524080A GB2181528B (en) 1985-09-30 1985-09-30 Air separation

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Publication Number Publication Date
JPS62142985A JPS62142985A (en) 1987-06-26
JP2773858B2 true JP2773858B2 (en) 1998-07-09

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ZA (1) ZA867376B (en)

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US4934148A (en) * 1989-05-12 1990-06-19 Union Carbide Corporation Dry, high purity nitrogen production process and system
US5352272A (en) * 1991-01-30 1994-10-04 The Dow Chemical Company Gas separations utilizing glassy polymer membranes at sub-ambient temperatures
US5837032A (en) * 1991-01-30 1998-11-17 The Cynara Company Gas separations utilizing glassy polymer membranes at sub-ambient temperatures
US6406518B1 (en) * 2000-08-21 2002-06-18 Praxair Technology, Inc. Gas separation process using ceramic membrane and regenerators

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US2464891A (en) * 1943-08-28 1949-03-22 Linder Air Products Company Process of and apparatus for producing compressed oxygen
GB1258568A (en) * 1968-08-21 1971-12-30
WO1984003554A1 (en) * 1983-03-08 1984-09-13 Daido Oxygen Apparatus for producing high-purity nitrogen gas

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JPS62142985A (en) 1987-06-26
GB2181528B (en) 1989-09-06
GB8524080D0 (en) 1985-11-06
ZA867376B (en) 1987-05-27
GB2181528A (en) 1987-04-23

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