JP2006043599A - Method and system for parallel separation of oxygen gas and nitrogen gas - Google Patents

Method and system for parallel separation of oxygen gas and nitrogen gas Download PDF

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JP2006043599A
JP2006043599A JP2004228966A JP2004228966A JP2006043599A JP 2006043599 A JP2006043599 A JP 2006043599A JP 2004228966 A JP2004228966 A JP 2004228966A JP 2004228966 A JP2004228966 A JP 2004228966A JP 2006043599 A JP2006043599 A JP 2006043599A
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JP4538275B2 (en
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Kazuo Haruna
一生 春名
Hiroaki Sasano
廣昭 笹野
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Sumitomo Seika Chemicals Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for separating to acquire a high-purity oxygen gas from air or the like with a PSA gas separation apparatus and capable of separating to acquire a high-purity nitrogen gas continuously and efficiently from a desorption gas supplied continuously from the PSA gas separation apparatus, and a system. <P>SOLUTION: A PSA gas separation process in the PSA gas separation apparatus 1 and a membrane type gas separation process in a membrane type gas separator 2 are included. In the PSA gas separation process, an oxygen enriched gas, and the desorption gas containing mainly nitrogen and also oxygen are removed from oxygen- and nitrogen-containing gas such as air by a pressure fluctuation adsorption type gas separation method to be performed using an adsorption column filled with an adsorbent adsorbing nitrogen on a priority base. In the membrane type gas separation process, the desorption gas is separated into gas passing through a gas separation membrane 2A and gas not passing therethrough (nitrogen enrichment gas) by the gas separation membrane 2A while the pressure of the passing side of the gas separation membrane 2A through which oxygen is passed on a priority base is reduced at less than an atmospheric pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、酸素および窒素を含む混合ガス（例えば空気）から酸素ガスおよび窒素ガスを併行して分離するための方法およびシステムに関する。   The present invention relates to a method and system for concurrently separating oxygen gas and nitrogen gas from a mixed gas containing oxygen and nitrogen (eg, air).

空気から分離して得られる酸素ガスおよび窒素ガスは、多様な用途に利用されている。酸素ガスは、例えば、ゴミ溶融炉や、灰溶融炉、ガラス溶融炉の高温化、製鋼用電気炉の燃焼効率向上、化学プラントでの酸化反応、廃水処理装置における酸素曝気などに、利用されている。一方、窒素ガスは、例えば、ゴミ溶融炉や化学プラントにおけるガスシールやパージング、熱処理炉の雰囲気ガス調整、食品の包装用ガスシールなどに、利用されている。   Oxygen gas and nitrogen gas obtained by separating from air are used in various applications. Oxygen gas is used for, for example, raising the temperature of refuse melting furnaces, ash melting furnaces, glass melting furnaces, improving the combustion efficiency of steelmaking electric furnaces, oxidation reactions in chemical plants, oxygen aeration in wastewater treatment equipment, etc. Yes. On the other hand, nitrogen gas is used, for example, for gas sealing and purging in refuse melting furnaces and chemical plants, adjustment of atmospheric gas in heat treatment furnaces, gas sealing for food packaging, and the like.

空気から酸素ガスや窒素ガスを分離するのに実用的な手法の一つとして、圧力変動吸着法（ＰＳＡ法）が知られている。ＰＳＡ法によるガス分離では、所定成分を優先的に吸着するための吸着剤が充填された吸着塔を具備するＰＳＡガス分離装置が用いられ、吸着塔において、少なくとも吸着工程および脱着工程が実行される。吸着工程では、吸着塔に混合ガスを導入して当該混合ガス中の易吸着成分を高圧条件下で吸着剤に吸着させ、難吸着成分からなるガスを塔から導出する。脱着工程では、塔内圧力を降下させて易吸着成分を吸着剤から脱着させ、当該易吸着成分を主に含むガスを吸着塔から導出する。例えば、酸素よりも窒素を優先的に吸着することのできる吸着剤を使用し且つ混合ガスとして空気を吸着塔に導入する場合、酸素は、吸着工程にて難吸着成分として塔外に導出され、窒素は、易吸着成分として、吸着工程にて吸着剤に吸着され且つ脱着工程にて塔外に導出される。   As one of practical methods for separating oxygen gas and nitrogen gas from air, a pressure fluctuation adsorption method (PSA method) is known. In gas separation by the PSA method, a PSA gas separation apparatus including an adsorption tower filled with an adsorbent for preferentially adsorbing a predetermined component is used, and at least an adsorption process and a desorption process are performed in the adsorption tower. . In the adsorption step, the mixed gas is introduced into the adsorption tower, the easily adsorbed component in the mixed gas is adsorbed on the adsorbent under high pressure conditions, and the gas composed of the hardly adsorbed component is led out from the tower. In the desorption step, the pressure in the tower is lowered to desorb the easily adsorbed component from the adsorbent, and the gas mainly containing the easily adsorbed component is led out from the adsorbing tower. For example, when using an adsorbent capable of preferentially adsorbing nitrogen over oxygen and introducing air as a mixed gas into the adsorption tower, oxygen is led out of the tower as a difficult adsorption component in the adsorption process, Nitrogen is adsorbed by the adsorbent as an easily adsorbing component in the adsorption step and led out of the tower in the desorption step.

ＰＳＡ法においては、脱着工程にて減圧脱着されて塔外に導出される易吸着成分ガスよりも、吸着工程にて吸着塔を通過する難吸着成分ガスの方が、ガス濃度やガス量について安定している。そのため、ＰＳＡ法では、取得目的のガスを易吸着成分ガスとするよりも難吸着成分ガスとする方が、当該目的ガスを効率よく取得しやすい。したがって、ＰＳＡ法により空気から酸素を分離取得する際には、一般に、使用されるＰＳＡガス分離装置の吸着塔に窒素吸着性の吸着剤が充填され、吸着工程にて当該吸着塔から導出される酸素富化ガスが製品ガスとして回収される。また、ＰＳＡ法により空気から窒素を分離取得する際には、一般に、酸素吸着性の吸着剤が吸着塔に充填され、吸着工程にて当該吸着塔から導出される窒素富化ガスが製品ガスとして回収される。   In the PSA method, the difficultly adsorbed component gas that passes through the adsorption tower in the adsorption step is more stable in terms of gas concentration and gas amount than the easily adsorbed component gas that is desorbed in the desorption step and led out of the tower. is doing. For this reason, in the PSA method, it is easier to acquire the target gas more efficiently when the acquisition target gas is the hardly adsorbed component gas than when the acquisition target gas is the easily adsorbed component gas. Therefore, when oxygen is separated from air by the PSA method, the adsorption tower of the PSA gas separator to be used is generally filled with a nitrogen-adsorbing adsorbent and is extracted from the adsorption tower in the adsorption step. Oxygen-enriched gas is recovered as product gas. In addition, when nitrogen is separated from air by the PSA method, generally, an oxygen-adsorbing adsorbent is filled in an adsorption tower, and a nitrogen-enriched gas derived from the adsorption tower in the adsorption step is used as a product gas. Collected.

しかしながら、空気中の酸素を分離取得して利用するとともに空気中の窒素を分離取得して利用する必要が生ずる場合があり、この場合には、空気中に含まれる酸素および窒素を単一のシステムにより併行して分離取得することが可能な技術が望まれる。   However, in some cases, it may be necessary to separate and use oxygen in the air and to use nitrogen in the air separately. In this case, oxygen and nitrogen contained in the air may be used as a single system. Therefore, it is desirable to have a technique that can be separately acquired in parallel.

図６は、空気中の酸素および窒素を併行して分離するための従来システムの一例である酸素・窒素併行分離システムＸ３を表す。酸素・窒素併行分離システムＸ３は、ＰＳＡガス分離装置６１と、膜式ガス分離器６２と、貯蔵タンク６３と、圧縮機６４，６５と、真空ポンプ６６とを備え、これらは、配管を介して連結されている。配管における所定の箇所には複数の自動弁（図示略）が設けられており、システム稼動時には、各自動弁の開閉状態が適宜選択されることにより、システム内のガスの流れ状態が切り替えられる。ＰＳＡガス分離装置６１は、酸素よりも窒素を優先的に吸着する吸着剤が充填された吸着塔（図示略）を備える。また、膜式ガス分離器６２は、酸素を優先的に透過させるためのガス分離膜６２ａを有する。このような酸素・窒素併行分離システムは、例えば下記の特許文献１に記載されている。   FIG. 6 shows an oxygen / nitrogen combined separation system X3 which is an example of a conventional system for separating oxygen and nitrogen in air in parallel. The oxygen / nitrogen parallel separation system X3 includes a PSA gas separation device 61, a membrane gas separator 62, a storage tank 63, compressors 64 and 65, and a vacuum pump 66, which are connected via a pipe. It is connected. A plurality of automatic valves (not shown) are provided at predetermined locations in the piping, and when the system is in operation, the flow state of the gas in the system is switched by appropriately selecting the open / close state of each automatic valve. The PSA gas separation device 61 includes an adsorption tower (not shown) filled with an adsorbent that preferentially adsorbs nitrogen over oxygen. The membrane gas separator 62 includes a gas separation membrane 62a for preferentially permeating oxygen. Such an oxygen / nitrogen combined separation system is described in Patent Document 1 below, for example.

特開平５−２５３４３８号公報JP-A-5-253438

酸素・窒素併行分離システムＸ３の稼動時には、ＰＳＡガス分離装置６１の吸着塔において、吸着工程および脱着工程を含む１サイクルが繰り返され、空気から酸素富化ガスが分離取得される。吸着工程では、圧縮機６４が作動してＰＳＡガス分離装置６１の吸着塔に空気が供給され、塔内が所定の圧力にまで上昇した状態において、当該空気中の易吸着成分（主に窒素を含む）を吸着剤に吸着させ、当該吸着塔ないしＰＳＡガス分離装置６１から酸素富化ガスが導出される。この酸素富化ガスは、例えば、所定の用途に連続的に使用される。脱着工程では、真空ポンプ６６の作動により塔内が所定の圧力にまで降下された状態において、当該吸着塔内の吸着剤から易吸着成分（主に窒素を含む）が脱着され、塔内に残存する酸素とともに当該易吸着成分は脱着ガスとして塔外ないしＰＳＡガス分離装置６１外に排出される。脱着ガス中の酸素濃度は、脱着工程初期においては比較的に高く、時間の経過とともに次第に低下する傾向にある。   During the operation of the oxygen / nitrogen combined separation system X3, one cycle including the adsorption step and the desorption step is repeated in the adsorption tower of the PSA gas separation device 61, and the oxygen-enriched gas is separated and acquired from the air. In the adsorption process, when the compressor 64 is operated and air is supplied to the adsorption tower of the PSA gas separation device 61 and the inside of the tower rises to a predetermined pressure, the easily adsorbed component (mainly nitrogen is removed) from the air. The oxygen-enriched gas is led out from the adsorption tower or the PSA gas separation device 61. This oxygen-enriched gas is continuously used for a predetermined application, for example. In the desorption step, the easily adsorbed components (mainly containing nitrogen) are desorbed from the adsorbent in the adsorption tower in a state where the inside of the tower is lowered to a predetermined pressure by the operation of the vacuum pump 66 and remains in the tower. The easily adsorbed component together with the oxygen to be discharged is discharged out of the tower or outside the PSA gas separation device 61 as a desorption gas. The oxygen concentration in the desorption gas is relatively high at the initial stage of the desorption process, and tends to gradually decrease with time.

ＰＳＡガス分離装置６１からの脱着ガスの酸素濃度は酸素モニタにより常時的に検知され、脱着工程初期の比較的に酸素濃度の高い脱着ガスは、矢印Ｇ’で示すように、システム外に廃棄される。そして、脱着ガスの酸素濃度が所定の値にまで低下した時点で、当該廃棄は停止され、貯蔵タンク６３への脱着ガスの回収に切り替えられ、脱着ガスの回収が開始される。このような脱着ガスの廃棄およびその後の回収は、ＰＳＡガス分離装置６１から脱着ガスが排出されるごとに実行される。   The oxygen concentration of the desorbed gas from the PSA gas separation device 61 is constantly detected by an oxygen monitor, and the desorbed gas having a relatively high oxygen concentration at the beginning of the desorption process is discarded outside the system as indicated by an arrow G ′. The Then, when the oxygen concentration of the desorption gas is reduced to a predetermined value, the discarding is stopped, the desorption gas is switched to the recovery of the storage tank 63, and the recovery of the desorption gas is started. Such discarding of the desorbed gas and the subsequent recovery are performed each time the desorbed gas is discharged from the PSA gas separation device 61.

貯蔵タンク６３に回収された脱着ガスは、圧縮機６５の作動により所定の圧力で膜式ガス分離器６２に供給され、膜式ガス分離器６２のガス分離膜６２ａを透過する透過ガスと透過しない非透過ガスとに分離される。脱着ガス中の酸素はガス分離膜６２ａを優先的に透過し、これにより、酸素濃度が低下して窒素純度が高められた窒素富化ガスが非透過ガスとして膜式ガス分離器６２から排出される。この非透過ガスは、例えば、所定の用途に連続的に使用される。酸素・窒素併行分離システムＸ３によると、以上のようにして、空気から酸素富化ガスおよび窒素富化ガスが分離取得される。   The desorption gas collected in the storage tank 63 is supplied to the membrane gas separator 62 at a predetermined pressure by the operation of the compressor 65, and does not pass through the permeated gas that permeates the gas separation membrane 62a of the membrane gas separator 62. Separated into non-permeating gas. Oxygen in the desorption gas preferentially permeates through the gas separation membrane 62a, whereby a nitrogen-enriched gas whose oxygen concentration is reduced and nitrogen purity is increased is discharged from the membrane gas separator 62 as a non-permeate gas. The This non-permeating gas is continuously used for a predetermined application, for example. According to the oxygen / nitrogen combined separation system X3, the oxygen-enriched gas and the nitrogen-enriched gas are separated and acquired from the air as described above.

酸素・窒素併行分離システムＸ３においては、仮に、ＰＳＡガス分離装置６１からの脱着ガスの全てが、貯蔵タンク６３に一旦回収されずに連続的に圧縮機６５を経て膜式ガス分離器６２に供給され続けると、膜式ガス分離器６２から非透過ガスとして排出される窒素富化ガスの量は、経時的に比較的大きく変動してしまう。膜式ガス分離器６２に供給される脱着ガスの酸素分圧ないし酸素濃度が比較的大きく変動し、これにより、ガス分離膜６２ａにおける酸素透過のドライビングフォースが比較的大きく変動するからである。当該ドライビングフォースの変動は、ガス分離膜６２ａに対する酸素の透過量ないし酸素の非透過量の変動を来し、従って、膜式ガス分離器６２から排出される非透過ガス（窒素富化ガス）の量の変動を来す。そのため、酸素・窒素併行分離システムＸ３において、ＰＳＡガス分離装置６１からの脱着ガスの全てが貯蔵タンク６３に一旦回収されずに連続的に膜式ガス分離器６２に供給され続けると、非透過ガスとして取得される窒素富化ガスを、その供給量が不安定であるために不活性ガスとして適切に利用できない場合が生ずる。   In the oxygen / nitrogen parallel separation system X3, all of the desorbed gas from the PSA gas separation device 61 is supplied to the membrane gas separator 62 continuously through the compressor 65 without being once recovered in the storage tank 63. If this is continued, the amount of nitrogen-enriched gas discharged from the membrane gas separator 62 as non-permeate gas will fluctuate relatively with time. This is because the oxygen partial pressure or oxygen concentration of the desorption gas supplied to the membrane gas separator 62 fluctuates relatively greatly, and as a result, the driving force for oxygen permeation in the gas separation membrane 62a varies relatively. The fluctuation of the driving force results in fluctuation of the oxygen permeation amount or the oxygen non-permeation amount with respect to the gas separation membrane 62a. Therefore, the non-permeation gas (nitrogen-enriched gas) discharged from the membrane gas separator 62 is changed. The amount varies. Therefore, in the oxygen / nitrogen combined separation system X3, if all of the desorbed gas from the PSA gas separation device 61 is not recovered to the storage tank 63 and continuously supplied to the membrane gas separator 62, the non-permeating gas In some cases, the nitrogen-enriched gas obtained as (1) cannot be appropriately used as an inert gas because the supply amount thereof is unstable.

これに対し、上述したような本来の態様で稼動する酸素・窒素併行分離システムＸ３におては、ＰＳＡガス分離装置６１からの脱着ガスの廃棄および回収が所定のタイミングで切り替えられることにより、所定の酸素濃度領域（即ち窒素濃度領域）の脱着ガスが貯蔵タンク６３に一旦回収され、略一定の酸素濃度（即ち略一定の窒素純度）の脱着ガスが貯蔵タンク６３から膜式ガス分離器６２に供給される。そして、膜式ガス分離器６２に供給される脱着ガスの酸素分圧（ないし酸素濃度）の変動が小さいため、ガス分離膜６２ａに対する酸素の透過量の変動は少なく、膜式ガス分離器６２からは、略一定の流量で非透過ガス（窒素富化ガス）が排出されることとなる。   On the other hand, in the oxygen / nitrogen parallel separation system X3 operating in the original mode as described above, the disposal and recovery of the desorbed gas from the PSA gas separation device 61 are switched at a predetermined timing. The desorption gas in the oxygen concentration region (that is, the nitrogen concentration region) is once recovered in the storage tank 63, and the desorption gas having a substantially constant oxygen concentration (that is, substantially constant nitrogen purity) is transferred from the storage tank 63 to the membrane gas separator 62. Supplied. And since the fluctuation of the oxygen partial pressure (or oxygen concentration) of the desorption gas supplied to the membrane gas separator 62 is small, the fluctuation of the oxygen permeation amount with respect to the gas separation membrane 62a is small. The non-permeating gas (nitrogen-enriched gas) is discharged at a substantially constant flow rate.

しかしながら、ＰＳＡガス分離装置６１から膜式ガス分離器６２への脱着ガスの流れを分断する切替え用ライン構成および貯蔵タンク６３は、窒素富化ガスの分離取得操作を不連続化してシステムの複雑化を招来するので、好ましくない。加えて、このような切替え用ライン構成および貯蔵タンク６３は、システムの大型化を招来するので好ましくない。また、ＰＳＡガス分離装置６１から膜式ガス分離器６２への脱着ガスの流れを分断する期間が長いほど、貯蔵タンク６３はより大きな容量を必要として大型化する。例えば、ＰＳＡガス分離装置６１の吸着塔での３０秒間の脱着工程の間において、脱着工程開始から２０秒間の脱着初期・中期に排出される脱着ガス（酸素濃度は比較的高くて窒素純度は比較的に低い）を矢印Ｇ’で示すようにシステム外に廃棄し、脱着工程開始から２０〜３０秒間の脱着末期に排出される脱着ガス（酸素濃度は比較的低くて窒素純度は比較的に高い）を貯蔵タンク６３に貯蔵する場合、脱着初期・中期の２０秒間は貯蔵タンク６３に脱着ガスが貯蔵されないので、この間に貯蔵タンク６３から膜式ガス分離器６２にガスを供給するためには、貯蔵タンク６３には、予め、それまでの脱着工程において排出される脱着ガスを膜式ガス分離器６２に送出せずに余分に貯蔵しておく必要がある。このとき、真空ポンプ６６の作動により相応の圧力で脱着ガスを貯蔵タンク６３に導入する必要があるが、真空ポンプ６６の吐出圧力には一定の限界があるので、貯蔵タンク６３に対して脱着ガスを適切に導入するためには、貯蔵タンク６３には充分な容量が必要となる。上述の分断時間が長いほど、貯蔵タンク６３に予め余分に貯蔵しておくべき脱着ガスの量は増大し、従って、貯蔵タンク６３に要求される容量も増大して貯蔵タンク６３が大型化するのである。   However, the switching line configuration and the storage tank 63 for cutting off the flow of the desorbed gas from the PSA gas separator 61 to the membrane gas separator 62 make the system complicated by making the operation of separating and obtaining the nitrogen-enriched gas discontinuous. Is not preferable. In addition, such a switching line configuration and the storage tank 63 are not preferable because the system is enlarged. Further, the longer the period during which the flow of desorption gas from the PSA gas separation device 61 to the membrane gas separator 62 is divided, the larger the storage tank 63 is required to have a larger capacity. For example, during the 30-second desorption process in the adsorption tower of the PSA gas separation device 61, the desorption gas discharged in the initial and middle periods of 20 seconds from the start of the desorption process (the oxygen concentration is relatively high and the nitrogen purity is compared) As shown by arrow G ′, and desorbed gas (oxygen concentration is relatively low and nitrogen purity is relatively high) discharged at the end of desorption for 20 to 30 seconds from the start of the desorption process. ) Is stored in the storage tank 63, since the desorption gas is not stored in the storage tank 63 for 20 seconds in the initial and intermediate periods of the desorption, in order to supply gas from the storage tank 63 to the membrane gas separator 62 during this period, In the storage tank 63, it is necessary to store in advance the desorption gas discharged in the previous desorption process without sending it to the membrane gas separator 62. At this time, it is necessary to introduce the desorption gas into the storage tank 63 at an appropriate pressure by the operation of the vacuum pump 66. However, since the discharge pressure of the vacuum pump 66 has a certain limit, the desorption gas is discharged from the storage tank 63. In order to properly introduce the storage tank 63, the storage tank 63 needs to have a sufficient capacity. Since the amount of desorption gas that should be stored in advance in the storage tank 63 increases as the above-described division time is longer, the capacity required for the storage tank 63 also increases and the storage tank 63 becomes larger. is there.

本発明は、このような事情の下で考え出されたものであって、ＰＳＡガス分離装置により酸素・窒素混合ガスから高純度酸素ガスを分離取得するとともに、当該ＰＳＡガス分離装置から連続的に供給される脱着ガスから高純度窒素ガスを連続的に効率よく分離取得することのできる、方法およびシステムを提供することを、目的とする。   The present invention has been conceived under such circumstances. A high-purity oxygen gas is separated and acquired from an oxygen / nitrogen mixed gas by a PSA gas separation device, and continuously from the PSA gas separation device. It is an object of the present invention to provide a method and system capable of continuously and efficiently separating and obtaining high-purity nitrogen gas from supplied desorption gas.

本発明の第１の側面によると、酸素および窒素を含む混合ガスから酸素ガスおよび窒素ガスを併行分離するための方法が提供される。この併行分離方法は、圧力変動吸着式ガス分離工程および膜式ガス分離工程を含む。圧力変動吸着式ガス分離工程では、窒素を優先的に吸着するための吸着剤が充填された吸着塔を用いて行う圧力変動吸着式ガス分離法により、吸着塔内が相対的に高圧である状態において、吸着塔に混合ガスを導入して当該混合ガス中の窒素を吸着剤に吸着させ、当該吸着塔から酸素富化ガスを導出し、且つ、吸着塔内が相対的に低圧である状態において、吸着剤から窒素を脱着させ、吸着塔内に残存する酸素と当該窒素とを含む酸素含有脱着ガスを当該吸着塔から導出する。膜式ガス分離工程では、酸素を優先的に透過させるためのガス分離膜の透過側を大気圧未満の圧力に減圧しつつ、当該ガス分離膜により、酸素含有脱着ガスを、ガス分離膜を透過する透過ガスおよび透過しない非透過窒素富化ガスに分離する。   According to a first aspect of the present invention, there is provided a method for parallel separation of oxygen gas and nitrogen gas from a mixed gas containing oxygen and nitrogen. This parallel separation method includes a pressure fluctuation adsorption gas separation step and a membrane gas separation step. In the pressure fluctuation adsorption gas separation process, the pressure tower is at a relatively high pressure by the pressure fluctuation adsorption gas separation method using an adsorption tower filled with an adsorbent for preferentially adsorbing nitrogen. In the state where the mixed gas is introduced into the adsorption tower, the nitrogen in the mixed gas is adsorbed by the adsorbent, the oxygen-enriched gas is led out from the adsorption tower, and the inside of the adsorption tower is at a relatively low pressure Then, nitrogen is desorbed from the adsorbent, and oxygen-containing desorption gas containing oxygen remaining in the adsorption tower and the nitrogen is led out from the adsorption tower. In the membrane gas separation process, the permeation side of the gas separation membrane for preferentially permeating oxygen is reduced to a pressure lower than atmospheric pressure, and the gas separation membrane allows oxygen-containing desorption gas to pass through the gas separation membrane. Separating into a permeate gas that permeates and a non-permeate nitrogen-enriched gas that does not permeate.

本併行分離方法においては、ガス分離膜の透過側を大気圧未満の所望の圧力に減圧することにより、圧力変動吸着式ガス分離工程における吸着塔から排出されて膜式ガス分離工程に付される酸素含有脱着ガスの酸素分圧（ないし、体積あたりの物質量で表される酸素濃度）と、当該酸素含有脱着ガスとはガス分離膜により隔てられている透過ガスの酸素分圧（ないし、体積あたりの物質量で表される酸素濃度）とについて、充分な差を設けることができる。酸素含有脱着ガスの酸素分圧（ないし酸素濃度）が変動する場合であっても、当該両酸素分圧について充分な差を設けることにより、ガス分離膜における酸素透過のための充分なドライビングフォースを確保することができるとともに当該ドライビングフォースの変動比率を抑制することができ、従って、ガス分離膜に対する酸素の充分な透過量を達成できるとともに当該透過量の変動比率を抑制することができる。ガス分離膜における酸素透過量が多いほど、当該膜における窒素透過量は少なく、従って、膜式ガス分離工程における非透過窒素富化ガスの発生量は多い。一方、ガス分離膜における酸素透過量の変動比率が小さいほど、膜式ガス分離工程における非透過窒素富化ガスの発生量の変動比率は小さい。このように、本併行分離方法によると、多量の非透過窒素富化ガスを安定した流量で供給することができる。したがって、本併行分離方法によると、ＰＳＡガス分離装置により酸素・窒素混合ガスから高純度酸素ガスを分離取得するとともに、ＰＳＡガス分離装置から連続的に供給される酸素含有脱着ガスから高純度窒素ガスを連続的に効率よく分離取得することが、可能なのである。そのため、本併行分離方法によると、ＰＳＡガス分離装置からの脱着ガスを一旦貯留するためのタンク等を用いる必要はない。   In this parallel separation method, by reducing the permeation side of the gas separation membrane to a desired pressure lower than atmospheric pressure, the gas separation membrane is discharged from the adsorption tower in the pressure fluctuation adsorption type gas separation step and subjected to the membrane type gas separation step. The oxygen partial pressure of the oxygen-containing desorption gas (or oxygen concentration expressed by the amount of substance per volume) and the oxygen partial pressure (or volume of the permeated gas separated from the oxygen-containing desorption gas by a gas separation membrane) A sufficient difference can be provided with respect to the oxygen concentration expressed by the amount of the per substance. Even when the oxygen partial pressure (or oxygen concentration) of the oxygen-containing desorption gas varies, a sufficient driving force for oxygen permeation through the gas separation membrane can be obtained by providing a sufficient difference between the two oxygen partial pressures. It can be ensured and the fluctuation ratio of the driving force can be suppressed, so that a sufficient amount of oxygen permeation through the gas separation membrane can be achieved and the fluctuation ratio of the permeation amount can be suppressed. The greater the amount of oxygen permeated through the gas separation membrane, the smaller the amount of nitrogen permeated through the membrane, and the greater the amount of non-permeated nitrogen-enriched gas generated in the membrane gas separation process. On the other hand, the smaller the fluctuation ratio of the oxygen permeation amount in the gas separation membrane, the smaller the fluctuation ratio of the non-permeated nitrogen-enriched gas generation amount in the membrane gas separation process. Thus, according to this parallel separation method, a large amount of non-permeated nitrogen-enriched gas can be supplied at a stable flow rate. Therefore, according to this parallel separation method, the high-purity oxygen gas is separated and obtained from the oxygen / nitrogen mixed gas by the PSA gas separation device, and the high-purity nitrogen gas from the oxygen-containing desorption gas continuously supplied from the PSA gas separation device. Can be obtained continuously and efficiently. Therefore, according to this parallel separation method, there is no need to use a tank or the like for temporarily storing desorption gas from the PSA gas separation device.

好ましくは、本併行分離方法は、酸素含有脱着ガスが膜式ガス分離工程に付される前に当該酸素含有脱着ガスを圧縮するための圧縮工程を更に含む。この場合、圧縮工程では、酸素含有脱着ガスを０.６ＭＰａ以上の圧力に圧縮するのが好ましい。このような構成は、吸着塔からの酸素含有脱着ガスの酸素分圧と、当該酸素含有脱着ガスとはガス分離膜により隔てられている透過ガスの酸素分圧とについて、充分な差を設けるうえで、好適である。   Preferably, the parallel separation method further includes a compression step for compressing the oxygen-containing desorption gas before the oxygen-containing desorption gas is subjected to the membrane gas separation step. In this case, in the compression step, the oxygen-containing desorption gas is preferably compressed to a pressure of 0.6 MPa or more. Such a configuration provides a sufficient difference between the oxygen partial pressure of the oxygen-containing desorption gas from the adsorption tower and the oxygen partial pressure of the permeated gas separated from the oxygen-containing desorption gas by a gas separation membrane. It is preferable.

好ましくは、圧力変動吸着式ガス分離工程における吸着塔から酸素含有脱着ガスを導出するときの当該吸着塔内の減圧と、膜式ガス分離工程における透過側の減圧とは、単一の減圧手段により実現される。このような構成は、本併行分離方法を効率よく実施するうえで好適である。   Preferably, the pressure reduction in the adsorption tower when the oxygen-containing desorption gas is led out from the adsorption tower in the pressure fluctuation adsorption gas separation step and the pressure reduction on the permeate side in the membrane gas separation step are performed by a single pressure reduction means. Realized. Such a configuration is suitable for efficiently carrying out the parallel separation method.

本発明の第２の側面によると、酸素および窒素を含む混合ガスから酸素ガスおよび窒素ガスを併行分離するためのシステムが提供される。この併行分離システムは、圧力変動吸着式ガス分離装置、膜式ガス分離器、および減圧手段を備える。圧力変動吸着式ガス分離装置は、窒素を優先的に吸着するための吸着剤が充填された吸着塔を有し、当該吸着塔を用いて行う圧力変動吸着式ガス分離法により、吸着塔内が相対的に高圧である状態において、吸着塔に混合ガスを導入して当該混合ガス中の窒素を吸着剤に吸着させ、当該吸着塔から酸素富化ガスを導出し、且つ、吸着塔内が相対的に低圧である状態において、吸着剤から窒素を脱着させ、吸着塔内に残存する酸素と当該窒素とを含む酸素含有脱着ガスを当該吸着塔から導出するためのものである。膜式ガス分離器は、酸素を優先的に透過させるためのガス分離膜を有し、酸素含有脱着ガスを、ガス分離膜を透過する透過ガスおよび透過しない非透過窒素富化ガスに分離して導出するためのものである。減圧手段は、膜式ガス分離器のガス分離膜における透過側を大気圧未満の圧力に減圧するためのものである。本併行分離システムによると、本発明の第１の側面の方法を適切に行うことができる。したがって、本併行分離システムによると、その酸素・窒素併行分離過程において、第１の側面に関して上述したのと同様の効果が奏される。   According to a second aspect of the present invention, a system for parallel separation of oxygen gas and nitrogen gas from a mixed gas containing oxygen and nitrogen is provided. This parallel separation system includes a pressure fluctuation adsorption gas separation device, a membrane gas separator, and a decompression means. The pressure fluctuation adsorption gas separation apparatus has an adsorption tower filled with an adsorbent for preferentially adsorbing nitrogen, and the inside of the adsorption tower is obtained by a pressure fluctuation adsorption gas separation method performed using the adsorption tower. In a state where the pressure is relatively high, the mixed gas is introduced into the adsorption tower, the nitrogen in the mixed gas is adsorbed by the adsorbent, the oxygen-enriched gas is led out from the adsorption tower, and the inside of the adsorption tower is relatively In this state, nitrogen is desorbed from the adsorbent at a low pressure, and oxygen-containing desorbed gas containing oxygen remaining in the adsorption tower and the nitrogen is led out from the adsorption tower. The membrane gas separator has a gas separation membrane for preferentially permeating oxygen, and separates the oxygen-containing desorption gas into a permeated gas that permeates the gas separation membrane and a non-permeated non-permeated nitrogen-enriched gas. It is for deriving. The decompression means is for decompressing the permeation side of the gas separation membrane of the membrane gas separator to a pressure lower than atmospheric pressure. According to the parallel separation system, the method of the first aspect of the present invention can be appropriately performed. Therefore, according to the present parallel separation system, the same effect as described above with respect to the first aspect can be achieved in the oxygen / nitrogen parallel separation process.

好ましくは、本併行分離システムは、酸素含有脱着ガスが膜式ガス分離器に供給される前に当該酸素含有脱着ガスを圧縮するための圧縮手段を更に備える。このような構成によると、第１の側面において上述した圧縮工程を行うことができる。   Preferably, the parallel separation system further comprises compression means for compressing the oxygen-containing desorption gas before the oxygen-containing desorption gas is supplied to the membrane gas separator. According to such a structure, the compression process mentioned above in the 1st side surface can be performed.

好ましくは、減圧手段は、圧力変動吸着式ガス分離装置の吸着塔から酸素含有脱着ガスを導出するときに当該吸着塔内を減圧するための手段としても併せて機能する。このような構成は、本併行分離システムをコンパクトに構築するうえで好適である。   Preferably, the depressurization means also functions as a means for depressurizing the inside of the adsorption tower when the oxygen-containing desorption gas is derived from the adsorption tower of the pressure fluctuation adsorption gas separation apparatus. Such a configuration is suitable for constructing the parallel separation system compactly.

図１は、本発明の第１の実施形態に係る酸素・窒素併行分離システムＸ１を表す。酸素・窒素併行分離システムＸ１は、圧力変動吸着式（ＰＳＡ）ガス分離装置１と、膜式ガス分離器２と、原料ガス供給装置３と、ポンプ４，５と、サイレンサ６と、圧縮機７と、気液分離器８と、酸素濃度制御機構９と、これらを連結する配管とを備え、空気（酸素・窒素含有原料ガス）から酸素富化ガスおよび窒素富化ガスを併行して分離すべく、圧力変動吸着式ガス分離工程、圧縮工程、および膜式ガス分離工程を含む酸素・窒素併行分離方法を実施するように構成されている。   FIG. 1 shows an oxygen / nitrogen parallel separation system X1 according to the first embodiment of the present invention. The oxygen / nitrogen parallel separation system X1 includes a pressure fluctuation adsorption (PSA) gas separation device 1, a membrane gas separator 2, a raw material gas supply device 3, pumps 4 and 5, a silencer 6, and a compressor 7. A gas-liquid separator 8, an oxygen concentration control mechanism 9, and a pipe connecting them, and separates the oxygen-enriched gas and the nitrogen-enriched gas from the air (oxygen / nitrogen-containing source gas) in parallel. Accordingly, the oxygen / nitrogen parallel separation method including the pressure fluctuation adsorption gas separation step, the compression step, and the membrane gas separation step is implemented.

ＰＳＡガス分離装置１は、主に窒素を優先的に吸着するための吸着剤が充填された少なくとも一つの吸着塔（図示略）を備え、当該吸着塔を用いて行う圧力変動吸着式ガス分離法により酸素・窒素含有原料ガス（本実施形態では空気）から酸素富化ガスを取り出すことのできるものである。吸着塔に充填される吸着剤としては、Ｌｉ−Ｘ型ゼオライトモレキュラーシーブ、Ｃａ−Ｘ型ゼオライトモレキュラーシーブ、およびＣａ−Ａ型ゼオライトモレキュラーシーブなどを採用することができる。単一の吸着塔には、一種類の吸着剤を充填してもよいし、複数種類の吸着剤を充填してもよい。   The PSA gas separation apparatus 1 includes at least one adsorption tower (not shown) filled with an adsorbent for mainly preferentially adsorbing nitrogen, and a pressure fluctuation adsorption type gas separation method performed using the adsorption tower. Thus, the oxygen-enriched gas can be taken out from the oxygen / nitrogen-containing source gas (air in the present embodiment). As the adsorbent filled in the adsorption tower, it is possible to employ Li-X type zeolite molecular sieve, Ca-X type zeolite molecular sieve, Ca-A type zeolite molecular sieve, and the like. A single adsorption tower may be filled with one kind of adsorbent, or may be filled with plural kinds of adsorbents.

ＰＳＡガス分離装置１にて実行される圧力変動吸着式ガス分離法では、単一の吸着塔について、吸着工程、脱着工程、および再生工程を含む１サイクルが繰り返される。吸着工程は、塔内が所定の高圧状態にある吸着塔に空気を導入して当該原料ガス中の窒素およびその他の成分（二酸化炭素，湿分など）を吸着剤に吸着させ、当該吸着塔から酸素富化ガスを導出するための工程である。脱着工程は、吸着塔内を減圧して吸着剤から窒素を脱着させ、当該窒素を塔外に排出するための工程である。再生工程は、再度の吸着工程に吸着塔を備えさせるべく、例えば洗浄ガスを塔内に通流させることにより、窒素に対する吸着剤の吸着性能を回復させるための工程である。このようなＰＳＡガス分離装置１としては、公知のＰＳＡ酸素分離装置を用いることができる。   In the pressure fluctuation adsorption type gas separation method executed in the PSA gas separation apparatus 1, one cycle including an adsorption step, a desorption step, and a regeneration step is repeated for a single adsorption tower. In the adsorption step, air is introduced into an adsorption tower having a predetermined high pressure in the tower to adsorb nitrogen and other components (carbon dioxide, moisture, etc.) in the raw material gas to the adsorbent, and from the adsorption tower It is a process for deriving oxygen-enriched gas. The desorption step is a step for depressurizing the inside of the adsorption tower to desorb nitrogen from the adsorbent and discharging the nitrogen out of the tower. The regeneration step is a step for recovering the adsorption performance of the adsorbent for nitrogen, for example, by passing a cleaning gas through the tower in order to provide the adsorption column in the second adsorption step. As such a PSA gas separation apparatus 1, a known PSA oxygen separation apparatus can be used.

膜式ガス分離器２は、導入口２ａおよび導出口２ｂ，２ｃを有し、酸素を優先的に透過させるガス分離膜２Ａを備える。膜式ガス分離器２の内部には所定のガス流路（具体的には図示せず）が設けられ、導入口２ａと導出口２ｂはガス流路の一部を介して連通している。また、導入口２ａから導出口２ｃまでのガス流路の所定箇所に、ガス分離膜２Ａは配設されている。ガス分離膜２Ａは、例えば、ポリイミドやポリスルホンなどよりなる多孔質樹脂膜である。そのような多孔質樹脂膜としては、ユーピレックスＰＴ（宇部興産（株）製）を用いることができる。   The membrane gas separator 2 has an inlet 2a and outlets 2b and 2c, and includes a gas separation membrane 2A that preferentially permeates oxygen. A predetermined gas flow path (specifically not shown) is provided inside the membrane gas separator 2, and the inlet 2a and outlet 2b communicate with each other through part of the gas flow path. In addition, a gas separation membrane 2A is disposed at a predetermined location in the gas flow path from the inlet 2a to the outlet 2c. The gas separation membrane 2A is a porous resin membrane made of, for example, polyimide or polysulfone. As such a porous resin film, Upilex PT (manufactured by Ube Industries, Ltd.) can be used.

原料ガス供給装置３は、酸素・窒素含有原料ガスである空気をＰＳＡガス分離装置１の吸着塔に供給するためのものであり、例えば空気ブロアである。ポンプ４は、ＰＳＡガス分離装置１の吸着塔内を吸引減圧するためのものであり、例えば真空ポンプである。また、ポンプ５は、膜式ガス分離器２におけるガス分離膜２Ａの透過側（ガス分離膜２Ａから導出口２ｃまでのガス流路）を吸引減圧するためのものであり、例えば真空ポンプである。   The raw material gas supply device 3 is for supplying air, which is an oxygen / nitrogen-containing raw material gas, to the adsorption tower of the PSA gas separation device 1, and is, for example, an air blower. The pump 4 is for sucking and depressurizing the inside of the adsorption tower of the PSA gas separation apparatus 1, and is, for example, a vacuum pump. The pump 5 is for sucking and reducing the permeation side (gas flow path from the gas separation membrane 2A to the outlet 2c) of the gas separation membrane 2A in the membrane gas separator 2, and is a vacuum pump, for example. .

サイレンサ６は、ポンプ４からのガスの一部を圧縮機７に導きつつ、ポンプ４からのガスの残部をシステム外に排出するためのものであり、ポンプ４からのガスを圧縮機７に導くためのガス流路と、ポンプ４からのガスを消音しつつシステム外に排出するためのガス流路とを有する。   The silencer 6 is for exhausting the remaining gas from the pump 4 to the outside of the system while guiding a part of the gas from the pump 4 to the compressor 7, and guides the gas from the pump 4 to the compressor 7. A gas flow path for discharging the gas from the pump 4 to the outside of the system while silencing the gas.

圧縮機７は、サイレンサ６を経たガスを圧縮して気液分離器８に供給するためのものである。また、気液分離器８は、排出口８ａを有しており、圧縮機７から送出されるガスに含まれる水分を当該ガスから分離するためのものである。排出口８ａは、気液分離器８内に回収された水分を気液分離器８外に排出するためのものである。   The compressor 7 is for compressing the gas that has passed through the silencer 6 and supplying the compressed gas to the gas-liquid separator 8. The gas-liquid separator 8 has a discharge port 8a, and is used to separate moisture contained in the gas sent from the compressor 7 from the gas. The discharge port 8 a is for discharging the water collected in the gas-liquid separator 8 to the outside of the gas-liquid separator 8.

酸素濃度制御機構９は、膜式ガス分離器２の導出口２ｂに継合された配管Ｌ１に設けられた酸素センサ９ａおよび自動弁９ｂからなり、配管Ｌ１内を通流するガスの酸素濃度に応じて、当該ガスの通流量（即ち、膜式ガス分離器２のガス分離膜２Ａを透過しないガスの量）を調節することにより、当該ガスの酸素濃度を所望の値に調整するためのものである。酸素センサ９ａは、配管Ｌ１内を通流するガスの酸素濃度を常時的に検知するためのものである。酸素濃度制御機構９においては、酸素センサ９ａの検知結果に応じて自動弁９ｂの開口度が所望に調節されるように構成されている。   The oxygen concentration control mechanism 9 includes an oxygen sensor 9a and an automatic valve 9b provided in the pipe L1 connected to the outlet 2b of the membrane gas separator 2, and adjusts the oxygen concentration of the gas flowing through the pipe L1. Accordingly, by adjusting the flow rate of the gas (that is, the amount of gas that does not permeate the gas separation membrane 2A of the membrane gas separator 2), the oxygen concentration of the gas is adjusted to a desired value. It is. The oxygen sensor 9a is for constantly detecting the oxygen concentration of the gas flowing through the pipe L1. The oxygen concentration control mechanism 9 is configured such that the opening degree of the automatic valve 9b is adjusted as desired according to the detection result of the oxygen sensor 9a.

以上の構成を有する酸素・窒素併行分離システムＸ１の稼動時には、原料ガス供給装置３の作動により、原料ガス供給装置３からＰＳＡガス分離装置１へと空気が供給される。   When the oxygen / nitrogen parallel separation system X1 having the above configuration is in operation, air is supplied from the source gas supply device 3 to the PSA gas separation device 1 by the operation of the source gas supply device 3.

ＰＳＡガス分離装置１においては、空気は圧力変動吸着式ガス分離工程に付される。具体的には、ＰＳＡガス分離装置１では、圧力変動吸着式ガス分離法により、吸着塔ごとに、吸着工程、脱着工程、および再生工程を含む１サイクルが繰り返される。   In the PSA gas separation apparatus 1, air is subjected to a pressure fluctuation adsorption gas separation process. Specifically, in the PSA gas separation apparatus 1, one cycle including an adsorption process, a desorption process, and a regeneration process is repeated for each adsorption tower by the pressure fluctuation adsorption gas separation method.

吸着工程では、塔内が所定の高圧状態にある吸着塔に、空気が導入される。当該吸着塔では、空気に含まれる窒素およびその他の成分（二酸化炭素，湿分など）が吸着剤により吸着除去され、高純度酸素ガス（酸素富化ガス）が塔外へ導出される。この高純度酸素ガスは、所定の配管を介して酸素・窒素併行分離システムＸ１外に取り出される。   In the adsorption step, air is introduced into the adsorption tower in which the inside of the tower is in a predetermined high pressure state. In the adsorption tower, nitrogen and other components (carbon dioxide, moisture, etc.) contained in the air are adsorbed and removed by the adsorbent, and high-purity oxygen gas (oxygen-enriched gas) is led out of the tower. This high purity oxygen gas is taken out of the oxygen / nitrogen parallel separation system X1 through a predetermined pipe.

脱着工程では、ポンプ４の作動により、吸着塔が減圧されて吸着剤から窒素およびその他の成分が脱着され、塔内に残存する酸素と当該脱着成分とを含む酸素含有脱着ガスが塔外ないしＰＳＡガス分離装置１外に排出される。脱着工程にある吸着塔から排出される酸素含有脱着ガスにおける圧力の時間変化の一例を表すグラフを、図２に示す。図２のグラフにおいて、横軸は、吸着塔における脱着時間（脱着工程開始からの経過時間）を表し、縦軸は、脱着圧力（酸素含有脱着ガスの圧力）を表す。本圧力変化例では、脱着工程開始時の圧力は大気圧であり、１０秒経過時の圧力は０.０６１１ＭＰａであり、３０秒経過時の圧力は０.０３３２ＭＰａである。また、図２には、脱着工程開始時、１０秒経過時、および３０秒経過時における、酸素含有脱着ガスの酸素濃度（酸素の体積割合）も併せて示した。   In the desorption step, the adsorption tower is depressurized by the operation of the pump 4 and nitrogen and other components are desorbed from the adsorbent, and oxygen-containing desorption gas containing oxygen remaining in the tower and the desorption component is outside the tower or PSA. It is discharged out of the gas separator 1. The graph showing an example of the time change of the pressure in the oxygen-containing desorption gas discharged | emitted from the adsorption tower in a desorption process is shown in FIG. In the graph of FIG. 2, the horizontal axis represents the desorption time (elapsed time from the start of the desorption process) in the adsorption tower, and the vertical axis represents the desorption pressure (pressure of the oxygen-containing desorption gas). In this pressure change example, the pressure at the start of the desorption process is atmospheric pressure, the pressure after 10 seconds has passed is 0.0611 MPa, and the pressure after 30 seconds has passed is 0.0332 MPa. FIG. 2 also shows the oxygen concentration (volume ratio of oxygen) of the oxygen-containing desorption gas at the start of the desorption process, at the time of 10 seconds, and at the time of 30 seconds.

再生工程では、例えば洗浄ガスが塔内に通流されることにより、主に窒素に対する吸着剤の吸着性能が回復される。再生工程を終えた吸着塔では上述の吸着が再び行われる。   In the regeneration step, for example, the cleaning gas is passed through the tower, so that the adsorption performance of the adsorbent mainly on nitrogen is recovered. The adsorption described above is performed again in the adsorption tower after the regeneration step.

ＰＳＡガス分離装置１においては、以上のような圧力変動吸着式ガス分離工程が行われることにより、高純度酸素ガスが取り出されるとともに、酸素含有脱着ガスが取り出されるのである。高純度酸素ガスは、例えば、所定の用途に連続的に使用されるか、或は、所定のタンクに貯留される。一方、脱着工程にある吸着塔からＰＳＡガス分離装置１外に排出された酸素含有脱着ガスは、所定の配管およびポンプ４を通ってサイレンサ６へと送られる。そして、酸素含有脱着ガスの一部は、サイレンサ６を通過して圧縮機７に至る。酸素含有脱着ガスの残部は、サイレンサ６にてシステム外に排出される。   In the PSA gas separation apparatus 1, by performing the pressure fluctuation adsorption gas separation step as described above, high-purity oxygen gas is taken out and oxygen-containing desorption gas is taken out. The high-purity oxygen gas is used continuously for a predetermined application, for example, or stored in a predetermined tank. On the other hand, the oxygen-containing desorption gas discharged from the adsorption tower in the desorption process to the outside of the PSA gas separation device 1 is sent to the silencer 6 through a predetermined pipe and the pump 4. A part of the oxygen-containing desorption gas passes through the silencer 6 and reaches the compressor 7. The remainder of the oxygen-containing desorption gas is discharged out of the system by the silencer 6.

サイレンサ６を通過した酸素含有脱着ガスは、圧縮機７にて圧縮され（圧縮工程）、気液分離器８を経て、膜式ガス分離器２に供給される。好ましくは、酸素含有脱着ガスは圧縮機７により０.６ＭＰａ以上の圧力まで圧縮される。また、気液分離器８では、酸素含有脱着ガスから水分が分離される。この水分は、排出口８ａを介して気液分離器８から外部に排出される。   The oxygen-containing desorbed gas that has passed through the silencer 6 is compressed by the compressor 7 (compression process) and supplied to the membrane gas separator 2 through the gas-liquid separator 8. Preferably, the oxygen-containing desorption gas is compressed by the compressor 7 to a pressure of 0.6 MPa or more. In the gas-liquid separator 8, moisture is separated from the oxygen-containing desorption gas. This moisture is discharged from the gas-liquid separator 8 to the outside through the discharge port 8a.

膜式ガス分離器２においては、酸素含有脱着ガスは膜式ガス分離工程に付される。具体的には、導入口２ａから膜式ガス分離器２内に導入される酸素含有脱着ガスＧ１は、膜式ガス分離器２のガス流路内に配設されているガス分離膜２Ａにより、ガス分離膜２Ａを透過する透過ガスＧ２と、透過しない非透過ガスＧ３とに、分離される。透過ガスＧ２は、ガス分離膜２Ａの透過特性に基づいて酸素濃度が高められた酸素富化ガスであり、非透過ガスＧ３は、ガス分離膜２Ａの透過特性に基づいて窒素濃度が高められた高純度窒素ガス（窒素富化ガス）である。   In the membrane gas separator 2, the oxygen-containing desorption gas is subjected to a membrane gas separation step. Specifically, the oxygen-containing desorption gas G1 introduced into the membrane gas separator 2 from the inlet 2a is caused by the gas separation membrane 2A disposed in the gas flow path of the membrane gas separator 2. The gas is separated into a permeate gas G2 that permeates the gas separation membrane 2A and a non-permeate gas G3 that does not permeate. The permeating gas G2 is an oxygen-enriched gas having an increased oxygen concentration based on the permeation characteristics of the gas separation membrane 2A, and the non-permeating gas G3 has an increased nitrogen concentration based on the permeation characteristics of the gas separation membrane 2A. High purity nitrogen gas (nitrogen-enriched gas).

膜式ガス分離工程では、ポンプ５の作動により、ガス分離膜２Ａの透過側は大気圧未満の圧力に減圧される。ポンプ５による減圧圧力は例えば０．０２〜０．０５ＭＰａである。透過ガスＧ２は、導出口２ｃから膜式ガス分離器２外に導出され、この後、ポンプ５を通ってシステム外に排出される。   In the membrane gas separation step, the permeation side of the gas separation membrane 2A is depressurized to a pressure lower than the atmospheric pressure by the operation of the pump 5. The reduced pressure by the pump 5 is, for example, 0.02 to 0.05 MPa. The permeating gas G2 is led out of the membrane gas separator 2 from the outlet 2c, and then is discharged out of the system through the pump 5.

これとともに、膜式ガス分離工程では、酸素濃度制御機構９の作動により、直接的には非透過ガス量が調節されて、非透過ガスＧ３の酸素濃度が一定に維持される。酸素濃度制御機構９の酸素センサ９ａは、導出口２ｂから膜式ガス分離器２外に導出されて配管Ｌ１内を通る非透過ガスＧ３について酸素濃度を常時的に検知する。検知濃度が所望値を上回る場合には、自動弁９ｂの開口度が小さくされ、配管Ｌ１内を通る非透過ガスＧ３の流量、ひいては膜式ガス分離器２での膜式ガス分離工程にて生ずる非透過ガスＧ３の量（単位時間あたりの発生量）は、低減される。一方、検知濃度が所望値を下回る場合には、自動弁９ｂの開口度が大きくされ、配管Ｌ１内を通る非透過ガスＧ３の流量、ひいては膜式ガス分離器２での膜式ガス分離工程にて生ずる非透過ガスＧ３の量は、増加される。膜式ガス分離工程での非透過ガスＧ３の純度および酸素濃度は、当該非透過ガスＧ３の発生量に依存して変化し得るので、このような非透過ガスＧ３の流量調節により当該非透過ガスＧ３の酸素濃度を制御することができるのである。   At the same time, in the membrane gas separation step, the amount of non-permeate gas is directly adjusted by the operation of the oxygen concentration control mechanism 9, and the oxygen concentration of the non-permeate gas G3 is maintained constant. The oxygen sensor 9a of the oxygen concentration control mechanism 9 constantly detects the oxygen concentration of the non-permeated gas G3 that is led out of the membrane gas separator 2 from the outlet 2b and passes through the pipe L1. When the detected concentration exceeds the desired value, the opening degree of the automatic valve 9b is reduced, and the flow rate of the non-permeate gas G3 passing through the pipe L1, and thus the membrane gas separation process in the membrane gas separator 2 occurs. The amount of the non-permeating gas G3 (the amount generated per unit time) is reduced. On the other hand, when the detected concentration is lower than the desired value, the opening degree of the automatic valve 9b is increased, and the flow rate of the non-permeate gas G3 passing through the pipe L1 and thus the membrane gas separation process in the membrane gas separator 2 are increased. The amount of non-permeate gas G3 produced is increased. Since the purity and oxygen concentration of the non-permeate gas G3 in the membrane gas separation step can vary depending on the amount of the non-permeate gas G3 generated, the non-permeate gas can be adjusted by adjusting the flow rate of the non-permeate gas G3. The oxygen concentration of G3 can be controlled.

膜式ガス分離器２においては、以上のような膜式ガス分離工程が行われることにより、酸素濃度制御が施されつつ高純度窒素ガスが取り出されるのである。この高純度窒素ガスは、例えば、所定の用途に連続的に使用されるか、或は、所定のタンクに貯留される。   In the membrane gas separator 2, the above-described membrane gas separation step is performed, whereby high-purity nitrogen gas is taken out while oxygen concentration control is performed. This high-purity nitrogen gas is continuously used for a predetermined application, for example, or stored in a predetermined tank.

酸素・窒素併行分離システムＸ１によると、以上のようにして、空気から高純度酸素ガスおよび高純度窒素ガスを併行して分離することができる。   According to the oxygen / nitrogen combined separation system X1, as described above, high-purity oxygen gas and high-purity nitrogen gas can be separated from air in parallel.

酸素・窒素併行分離システムＸ１による酸素・窒素併行分離方法おいては、圧力変動吸着式ガス分離工程が行われるＰＳＡガス分離装置１の吸着塔から排出されて膜式ガス分離器２での膜式ガス分離工程に付される酸素含有脱着ガスＧ１の酸素分圧（ないし、体積あたりの物質量で表される酸素濃度）と、当該酸素含有脱着ガスＧ１とはガス分離膜２Ａにより隔てられている透過ガスＧ２の酸素分圧（ないし、体積あたりの物質量で表される酸素濃度）とについて、ガス分離膜２Ａの透過側を大気圧未満の所望の圧力に減圧することにより、充分な差を設けることができる。また、圧縮機７での圧縮工程も、吸着塔からの酸素含有脱着ガスＧ１の酸素分圧と、ガス分離膜２Ａにより隔てられている透過ガスＧ２の酸素分圧とについて、充分な差を設けるのに寄与している。酸素含有脱着ガスＧ１の酸素分圧（ないし酸素濃度）が変動する場合であっても、当該両酸素分圧について充分な差を設けることにより、ガス分離膜２Ａにおける酸素透過のための充分なドライビングフォースを確保することができるとともに当該ドライビングフォースの変動比率を抑制することができ、従って、ガス分離膜２Ａに対する酸素の充分な透過量を得ることができるとともに当該透過量の変動を抑制することができる。ガス分離膜２Ａにおける酸素透過量が多いほど、ガス分離膜２Ａにおける窒素透過量は少ない傾向にあり、従って、膜式ガス分離器２での膜式ガス分離工程における非透過ガス（高純度窒素ガス）Ｇ３の発生量は多い傾向にある。一方、ガス分離膜２Ａにおける酸素透過量の変動比率が小さいほど、膜式ガス分離工程における非透過ガス（高純度窒素ガス）Ｇ３の発生量の変動比率は小さい傾向にある。   In the oxygen / nitrogen parallel separation method by the oxygen / nitrogen parallel separation system X1, the membrane type gas separator 2 discharges from the adsorption tower of the PSA gas separation apparatus 1 where the pressure fluctuation adsorption type gas separation step is performed. The oxygen partial pressure of the oxygen-containing desorption gas G1 subjected to the gas separation step (or the oxygen concentration represented by the amount of substance per volume) and the oxygen-containing desorption gas G1 are separated by the gas separation membrane 2A. By reducing the permeation side of the gas separation membrane 2A to a desired pressure less than atmospheric pressure, the oxygen partial pressure of the permeate gas G2 (or the oxygen concentration expressed by the amount of substance per volume) is sufficiently different. Can be provided. Further, the compression process in the compressor 7 also provides a sufficient difference between the oxygen partial pressure of the oxygen-containing desorption gas G1 from the adsorption tower and the oxygen partial pressure of the permeate gas G2 separated by the gas separation membrane 2A. Contributing to Even when the oxygen partial pressure (or oxygen concentration) of the oxygen-containing desorption gas G1 fluctuates, sufficient driving for oxygen permeation through the gas separation membrane 2A is achieved by providing a sufficient difference between the two oxygen partial pressures. The force can be secured and the fluctuation ratio of the driving force can be suppressed. Therefore, a sufficient amount of oxygen permeated to the gas separation membrane 2A can be obtained and the variation in the amount of permeation can be suppressed. it can. As the oxygen permeation amount in the gas separation membrane 2A increases, the nitrogen permeation amount in the gas separation membrane 2A tends to decrease. ) The amount of G3 generated tends to be large. On the other hand, the smaller the fluctuation ratio of the oxygen permeation amount in the gas separation membrane 2A, the smaller the fluctuation ratio of the generation amount of the non-permeating gas (high purity nitrogen gas) G3 in the membrane gas separation process.

このように、本発明に係る酸素・窒素併行分離システムＸ１による酸素・窒素併行分離方法によると、多量の非透過窒素富化ガスを安定した流量で供給することができる。したがって、本併行分離方法によると、ＰＳＡガス分離装置１により空気から高純度酸素ガスを分離取得するとともに、ＰＳＡガス分離装置１から連続的に供給される酸素含有脱着ガスから高純度窒素ガスを連続的に効率よく分離取得することが、可能なのである。そのため、本併行分離方法によると、ＰＳＡガス分離装置１からの酸素含有脱着ガスを一旦貯留するためのタンク等を用いる必要はない。   Thus, according to the oxygen / nitrogen parallel separation method by the oxygen / nitrogen parallel separation system X1 according to the present invention, a large amount of non-permeated nitrogen-enriched gas can be supplied at a stable flow rate. Therefore, according to this parallel separation method, the high-purity oxygen gas is separated from the air by the PSA gas separation device 1 and the high-purity nitrogen gas is continuously supplied from the oxygen-containing desorption gas continuously supplied from the PSA gas separation device 1. It is possible to separate and acquire efficiently. Therefore, according to this parallel separation method, it is not necessary to use a tank or the like for temporarily storing the oxygen-containing desorption gas from the PSA gas separation device 1.

本発明においては、膜式ガス分離器２に導入される酸素含有脱着ガスＧ１について、圧力をＰ1（ＭＰａ）、酸素濃度（酸素の体積割合）をＸ1、ガス量をＱ1（Ｎｍ3/hour）とし、膜式ガス分離器２から導出される透過ガスＧ２について、圧力（即ち、ガス分離膜２Ａの透過側の圧力）をＰ2（ＭＰａ）、酸素濃度をＸ2、ガス量をＱ2（Ｎｍ3/hour）とし、膜式ガス分離器２から導出される非透過ガス（高純度窒素ガス）Ｇ３について、酸素濃度をＸ3、ガス量をＱ3（Ｎｍ3/hour）とし、ガス分離膜２Ａの面積および厚さをＳ（ｍ2）およびＬ（ｍ）とし、ガス分離膜２Ａの酸素の透過係数をＫ（Ｎｍ2/hour・ＭＰａ）とすると、ガス分離膜２Ａによるガス分離について、理論上は下記の式（１）〜（３）が成立する。式（１）はガス量バランスを表し、式（２）は酸素量バランスを表し、式（３）はガス分離膜２Ａの酸素透過特性を表す。 In the present invention, for the oxygen-containing desorption gas G1 introduced into the membrane gas separator 2, the pressure is P 1 (MPa), the oxygen concentration (volume ratio of oxygen) is X 1 , and the gas amount is Q 1 (Nm 3 for the permeate gas G2 derived from the membrane gas separator 2, the pressure (that is, the pressure on the permeate side of the gas separation membrane 2A) is P 2 (MPa), the oxygen concentration is X 2 , and the gas amount is Q 2 (Nm 3 / hour), and for the non-permeate gas (high purity nitrogen gas) G3 derived from the membrane gas separator 2, the oxygen concentration is X 3 and the gas amount is Q 3 (Nm 3 / hour). When the area and thickness of the gas separation membrane 2A are S (m 2 ) and L (m) and the oxygen permeability coefficient of the gas separation membrane 2A is K (Nm 2 / hour · MPa), the gas separation membrane 2A The following formulas (1) to (3) are theoretically established for gas separation. Equation (1) represents the gas amount balance, Equation (2) represents the oxygen amount balance, and Equation (3) represents the oxygen permeation characteristic of the gas separation membrane 2A.

Figure 2006043599
Figure 2006043599

例えば、ガス分離膜２Ａとしてポリイミド多孔質膜であるユーピレックスＰＴ（宇部興産（株）製）を採用して式（３）のＫ（Ｓ／Ｌ）の値を１８６に設定し、ＰＳＡガス分離装置１から図２に示すように排出されていくこととなる、脱着工程開始時（脱着初期）において酸素濃度（Ｘ1）が２０.６％の酸素含有脱着ガスを、圧縮機７により０.７９ＭＰａ（Ｐ1）に圧縮して膜式ガス分離器２に１２５Ｎｍ3/hour（Ｑ1）の供給量で導入し、ガス分離膜２Ａの透過側の圧力を０.０３３２ＭＰａ（Ｐ2）に減圧し、残存酸素濃度（Ｘ3）が１％の非透過ガス（高純度窒素ガス）が得られるように酸素濃度制御機構９により非透過ガス流量を調整する場合には、３つの未知数Ｘ2，Ｑ2，Ｑ3を、上記式（１）〜（３）からなる連立方程式の解として求めることができ、脱着初期には、酸素濃度（Ｘ2）が８８.９％の透過ガスが２７.９Ｎｍ3/hour（Ｑ2）発生し、非透過ガス量（Ｑ3）は９７.１Ｎｍ3/hourとなることが判る。脱着初期におけるこれらの値は、図３の表に掲げる。 For example, as a gas separation membrane 2A, a polyimide porous membrane, Upilex PT (manufactured by Ube Industries, Ltd.) is adopted, the value of K (S / L) in formula (3) is set to 186, and a PSA gas separation device As shown in FIG. 2, oxygen-containing desorption gas having an oxygen concentration (X 1 ) of 20.6% at the start of the desorption process (initial desorption) is discharged by the compressor 7 to 0.79 MPa. (P 1 ) and introduced into the membrane gas separator 2 at a supply rate of 125 Nm 3 / hour (Q 1 ), and the pressure on the permeate side of the gas separation membrane 2 A is reduced to 0.0332 MPa (P 2 ). When the non-permeate gas flow rate is adjusted by the oxygen concentration control mechanism 9 so that a non-permeate gas (high purity nitrogen gas) having a residual oxygen concentration (X 3 ) of 1% is obtained, three unknowns X 2 , Q 2 and Q 3 are the solutions of the simultaneous equations consisting of the above equations (1) to (3). In the initial stage of desorption, 27.9 Nm 3 / hour (Q 2 ) of permeate gas having an oxygen concentration (X 2 ) of 88.9% is generated, and the amount of non-permeate gas (Q 3 ) is 97 It can be seen that it is 0.1 Nm 3 / hour. These values in the initial stage of desorption are listed in the table of FIG.

Ｋ（Ｓ／Ｌ），Ｐ1，Ｑ1，Ｐ2，Ｘ3の値を一定に保ちつつ、脱着工程開始から１０秒経過時（脱着中期）において酸素含有脱着ガスの酸素濃度（Ｘ1）が図２に示すように１０.０％に至ったときには、上記式（１）〜（３）からなる連立方程式の解としてＸ2，Ｑ2，Ｑ3を求めることにより、当該脱着中期には、酸素濃度（Ｘ2）が５２.２％の透過ガスが２２.０Ｎｍ3/hour（Ｑ2）で発生し、非透過ガス量（Ｑ3）は１０３.２Ｎｍ3/hourとなることが判る。脱着中期におけるこれらの値も、図３の表に掲げる。 While maintaining the values of K (S / L), P 1 , Q 1 , P 2 , and X 3 constant, the oxygen concentration (X 1 ) of the oxygen-containing desorption gas at the time when 10 seconds have elapsed from the start of the desorption process (desorption middle period) 2 reaches 10.0% as shown in FIG. 2, by obtaining X 2 , Q 2 , Q 3 as solutions of the simultaneous equations consisting of the above formulas (1) to (3), It can be seen that a permeate gas having an oxygen concentration (X 2 ) of 52.2% is generated at 22.0 Nm 3 / hour (Q 2 ), and the amount of non-permeate gas (Q 3 ) is 103.2 Nm 3 / hour. . These values in the middle of desorption are also listed in the table of FIG.

Ｋ（Ｓ／Ｌ），Ｐ1，Ｑ1，Ｐ2，Ｘ3の値を一定に保ちつつ、脱着工程開始から３０秒経過時（脱着末期）において酸素含有脱着ガスの酸素濃度（Ｘ1）が図２に示すように５.０％に至ったときには、上記式（１）〜（３）からなる連立方程式の解としてＸ2，Ｑ2，Ｑ3を求めることにより、当該脱着末期には、酸素濃度（Ｘ2）が３５.７％の透過ガスが１４.４Ｎｍ3/hourの量（Ｑ2）で発生し、非透過ガス量（Ｑ3）は１１０.６Ｎｍ3/hourとなることが判る。脱着末期におけるこれらの値も、図３の表に掲げる。 While maintaining the values of K (S / L), P 1 , Q 1 , P 2 , and X 3 constant, the oxygen concentration (X 1 ) of the oxygen-containing desorption gas after 30 seconds from the start of the desorption process (desorption end stage) 2 reaches 5.0% as shown in FIG. 2, by obtaining X 2 , Q 2 , and Q 3 as solutions of the simultaneous equations consisting of the above formulas (1) to (3), , the oxygen concentration (X 2) is 35.7% of the permeate gas generated in an amount of 14.4Nm 3 / hour (Q 2) , non-permeate gas quantity (Q 3) is to become 110.6Nm 3 / hour I understand. These values at the end of desorption are also listed in the table of FIG.

一方、ガス分離膜２Ａの透過側を減圧せずに大気圧（０.１０１ＭＰａ）とする以外は、上述の条件と同様にして、ＰＳＡガス分離装置１から図２に示すように酸素含有脱着ガスが排出される場合の脱着初期、脱着中期、および脱着末期のＸ2，Ｑ2，Ｑ3を式（１）〜（３）に基づいて求めると、その結果は、図４の表に示すとおりである。 On the other hand, the oxygen-containing desorption gas from the PSA gas separation device 1 as shown in FIG. When X 2 , Q 2 , and Q 3 at the initial stage of desorption, middle stage of desorption, and last stage of desorption are calculated based on the formulas (1) to (3), the results are as shown in the table of FIG. It is.

図３の表および図４の表の比較から理解できるように、膜式ガス分離工程においてガス分離膜２Ａの透過側を減圧しない場合には（図４参照）、透過ガス量（Ｑ2）は脱着初期から脱着末期にわたって比較的に多く、従って、非透過ガス量（Ｑ3）は脱着初期から脱着末期にわたって比較的に少ない。また、酸素含有脱着ガスの酸素濃度（Ｘ1）の低下に伴う透過ガス量（Ｑ2）の変化量（ないし変動比率）は大きく、従って、非透過ガス量（Ｑ3）の変化量（ないし変動比率）も大きい。これに対し、膜式ガス分離工程においてガス分離膜２Ａの透過側を大気圧未満に減圧する場合には（図３参照）、透過ガス量（Ｑ2）は脱着初期から脱着末期にわたって比較的に少なく、従って、非透過ガス量（Ｑ3）は脱着初期から脱着末期にわたって比較的に多い。また、酸素含有脱着ガスの酸素濃度（Ｘ1）の低下に伴う透過ガス量（Ｑ2）の変化量（ないし変動比率）は小さく、従って、非透過ガス量（Ｑ3）の変化量（ないし変動比率）も小さい。以上のことから、酸素・窒素併行分離システムＸ１における膜式ガス分離工程によると、多量の高純度窒素ガスを安定した流量で供給することができることが、理解できよう。 As can be understood from the comparison between the table of FIG. 3 and the table of FIG. 4, when the permeation side of the gas separation membrane 2A is not depressurized in the membrane gas separation process (see FIG. 4), the amount of permeated gas (Q 2 ) is Therefore, the amount of non-permeated gas (Q 3 ) is relatively small from the initial stage of desorption to the end stage of desorption. Further, the change amount (or fluctuation ratio) of the permeate gas amount (Q 2 ) accompanying the decrease in the oxygen concentration (X 1 ) of the oxygen-containing desorption gas is large, and accordingly, the change amount (or the non-permeate gas amount (Q 3 )) (or The fluctuation ratio is also large. On the other hand, when the permeation side of the gas separation membrane 2A is reduced to less than atmospheric pressure in the membrane gas separation step (see FIG. 3), the amount of permeated gas (Q 2 ) is relatively long from the initial stage of desorption to the last stage of desorption. Therefore, the amount of non-permeate gas (Q 3 ) is relatively large from the initial stage of desorption to the end of desorption. Further, the change amount (or fluctuation ratio) of the permeate gas amount (Q 2 ) accompanying the decrease in the oxygen concentration (X 1 ) of the oxygen-containing desorption gas is small, and accordingly, the change amount (or change amount) of the non-permeate gas amount (Q 3 ). The fluctuation ratio is also small. From the above, it can be understood that a large amount of high-purity nitrogen gas can be supplied at a stable flow rate according to the membrane gas separation process in the oxygen / nitrogen parallel separation system X1.

図５は、本発明の第２の実施形態に係る酸素・窒素併行分離システムＸ２を表す。酸素・窒素併行分離システムＸ２は、ポンプ５を備えない点、および、膜式ガス分離器２の導出口２ｃとポンプ４の吸引側とを継合する配管Ｌ２を備える点において、酸素・窒素併行分離システムＸ１と異なる。   FIG. 5 shows an oxygen / nitrogen parallel separation system X2 according to the second embodiment of the present invention. The oxygen / nitrogen combined separation system X2 is provided with a combination of oxygen and nitrogen in that it does not include the pump 5 and includes a pipe L2 that connects the outlet 2c of the membrane gas separator 2 and the suction side of the pump 4. Different from the separation system X1.

酸素・窒素併行分離システムＸ２におけるポンプ４は、ＰＳＡガス分離装置１の吸着塔内を減圧するための減圧手段として機能するとともに、膜式ガス分離器２におけるガス分離膜２Ａの透過側を減圧するための減圧手段としても機能する。このような構成は、システムをコンパクトに構築するうえで好適である。   The pump 4 in the oxygen / nitrogen parallel separation system X2 functions as a decompression means for decompressing the inside of the adsorption tower of the PSA gas separation apparatus 1, and decompresses the permeation side of the gas separation membrane 2A in the membrane gas separator 2. It also functions as a decompression means. Such a configuration is suitable for constructing the system compactly.

酸素・窒素併行分離システムＸ２の稼動時には、ＰＳＡガス分離装置１において、酸素・窒素併行分離システムＸ１に関して上述したのと同様に圧力変動吸着式ガス分離工程が行われることにより、高純度酸素ガスおよび酸素含有脱着ガスが取り出される。また、膜式ガス分離器２において、ガス分離膜２Ａの透過側の減圧手法以外は酸素・窒素併行分離システムＸ１に関して上述したのと同様に、膜式ガス分離工程が行われることにより、高純度窒素ガスが取り出される。本実施形態における膜式ガス分離工程では、ポンプ４の作動により、ガス分離膜２Ａの透過側は大気圧未満の圧力に減圧される。例えば、ポンプ４の作動により、吸着工程にある吸着塔内が吸引減圧されるのと同時に、ガス分離膜２Ａの透過側も減圧される。   When the oxygen / nitrogen combined separation system X2 is in operation, the PSA gas separation device 1 performs a pressure fluctuation adsorption gas separation step in the same manner as described above with respect to the oxygen / nitrogen combined separation system X1, thereby allowing high-purity oxygen gas and An oxygen-containing desorption gas is removed. Further, in the membrane gas separator 2, except for the pressure reduction method on the permeate side of the gas separation membrane 2A, the membrane gas separation process is performed in the same manner as described above with respect to the oxygen / nitrogen combined separation system X1, thereby achieving high purity. Nitrogen gas is removed. In the membrane gas separation process in the present embodiment, the permeation side of the gas separation membrane 2A is depressurized to a pressure lower than the atmospheric pressure by the operation of the pump 4. For example, by operating the pump 4, the inside of the adsorption tower in the adsorption process is sucked and depressurized, and at the same time, the permeate side of the gas separation membrane 2A is depressurized.

したがって、酸素・窒素併行分離システムＸ２による酸素・窒素併行分離方法によると、酸素・窒素併行分離システムＸ１によるのと略同様に、高純度酸素ガスを供給することができるのに加え、多量の高純度窒素ガスを安定した流量で供給することができるのである。   Therefore, according to the oxygen / nitrogen parallel separation method using the oxygen / nitrogen parallel separation system X2, in addition to being able to supply high-purity oxygen gas, as with the oxygen / nitrogen parallel separation system X1, a large amount of high Purity nitrogen gas can be supplied at a stable flow rate.

本発明の第１の実施形態に係る酸素・窒素併行分離システムの概略構成を表す。1 shows a schematic configuration of a parallel oxygen / nitrogen separation system according to a first embodiment of the present invention. 図１に示す圧力変動吸着式ガス分離装置から排出される酸素含有脱着ガスについて、圧力の時間変化の一例を表す。An example of the time change of a pressure is represented about the oxygen-containing desorption gas discharged | emitted from the pressure fluctuation | variation adsorption type gas separation apparatus shown in FIG. 図１に示す酸素・窒素併行分離システムを使用して実行される本発明の酸素・窒素併行分離方法における膜式ガス分離工程に関し、図２に示すようにＰＳＡガス分離装置から酸素含有脱着ガスが排出される場合の、脱着初期（脱着工程開始時）、脱着中期（１０秒経過時）、および脱着末期（３０秒経過時）にわたる各物理量の変化の一例をまとめた表である。FIG. 2 shows a membrane gas separation process in the oxygen / nitrogen parallel separation method of the present invention performed using the oxygen / nitrogen parallel separation system shown in FIG. It is the table | surface which put together an example of the change of each physical quantity over the desorption initial stage (at the time of desorption process start), the desorption middle period (at the time of 10 second passage), and the desorption end stage (at the time of 30 second passage) at the time of discharge | emission. 図１に示す酸素・窒素併行分離システムの膜式ガス分離器におけるガス分離膜の透過側を減圧せずに実行される膜式ガス分離工程に関し、図２に示すようにＰＳＡガス分離装置から酸素含有脱着ガスが排出される場合の、脱着初期（脱着工程開始時）、脱着中期（１０秒経過時）、および脱着末期（３０秒経過時）にわたる各物理量の変化の一例をまとめた表である。FIG. 2 shows a membrane gas separation process performed without depressurizing the permeation side of the gas separation membrane in the membrane gas separator of the oxygen / nitrogen separation system shown in FIG. It is the table | surface which put together an example of the change of each physical quantity over the desorption initial stage (at the time of desorption process start), the desorption middle period (at the time of 10 second passage), and the desorption end stage (at the time of 30 second passage) when the content desorption gas is discharged | emitted. . 本発明の第２の実施形態に係る酸素・窒素併行分離システムの概略構成を表す。The schematic structure of the oxygen and nitrogen parallel separation system which concerns on the 2nd Embodiment of this invention is represented. 従来の酸素・窒素併行分離システムの概略構成を表す。1 shows a schematic configuration of a conventional oxygen / nitrogen combined separation system.

符号の説明Explanation of symbols

Ｘ１，Ｘ２，Ｘ３ 酸素・窒素併行分離システム
１ ＰＳＡガス分離装置
２ 膜式ガス分離器
２Ａ ガス分離膜
３ 原料ガス供給装置
４，５ ポンプ
６ サイレンサ
７ 圧縮機
８ 気液分離器
９ 酸素濃度制御機構 X1, X2, X3 Oxygen / nitrogen parallel separation system 1 PSA gas separation device 2 Membrane gas separator 2A Gas separation membrane 3 Raw material gas supply device 4,5 Pump 6 Silencer 7 Compressor 8 Gas-liquid separator 9 Oxygen concentration control mechanism

Claims (7)

酸素および窒素を含む混合ガスから酸素ガスおよび窒素ガスを併行分離するための方法であって、
窒素を優先的に吸着するための吸着剤が充填された吸着塔を用いて行う圧力変動吸着式ガス分離法により、前記吸着塔内が相対的に高圧である状態において、前記吸着塔に前記混合ガスを導入して当該混合ガス中の窒素を前記吸着剤に吸着させ、当該吸着塔から酸素富化ガスを導出し、且つ、前記吸着塔内が相対的に低圧である状態において、前記吸着剤から前記窒素を脱着させ、前記吸着塔内に残存する酸素と当該窒素とを含む酸素含有脱着ガスを当該吸着塔から導出するための、圧力変動吸着式ガス分離工程と、
酸素を優先的に透過させるためのガス分離膜の透過側を大気圧未満の圧力に減圧しつつ、当該ガス分離膜により、前記酸素含有脱着ガスを、前記ガス分離膜を透過する透過ガスおよび透過しない非透過窒素富化ガスに分離するための、膜式ガス分離工程と、を含む、酸素ガスおよび窒素ガスの併行分離方法。 A method for concurrently separating oxygen gas and nitrogen gas from a mixed gas containing oxygen and nitrogen,
In the state where the inside of the adsorption tower is at a relatively high pressure, by the pressure fluctuation adsorption gas separation method using an adsorption tower filled with an adsorbent for preferentially adsorbing nitrogen, the mixing is performed in the adsorption tower. In the state where the gas is introduced to adsorb nitrogen in the mixed gas to the adsorbent, the oxygen-enriched gas is led out from the adsorption tower, and the inside of the adsorption tower is at a relatively low pressure. The pressure fluctuation adsorption gas separation step for desorbing the nitrogen from and deriving the oxygen-containing desorption gas containing oxygen remaining in the adsorption tower and the nitrogen from the adsorption tower;
While reducing the permeation side of the gas separation membrane for preferentially permeating oxygen to a pressure lower than atmospheric pressure, the gas separation membrane allows the oxygen-containing desorption gas to pass through the gas separation membrane and the permeated gas. And a membrane gas separation step for separating into a non-permeating nitrogen-enriched gas. 前記酸素含有脱着ガスが前記膜式ガス分離工程に付される前に当該酸素含有脱着ガスを圧縮するための圧縮工程を更に含む、請求項１に記載の併行分離方法。   The parallel separation method according to claim 1, further comprising a compression step for compressing the oxygen-containing desorption gas before the oxygen-containing desorption gas is subjected to the membrane gas separation step. 前記圧縮工程では、前記酸素含有脱着ガスを０.６ＭＰａ以上の圧力に圧縮する、請求項２に記載の併行分離方法。   The parallel separation method according to claim 2, wherein in the compression step, the oxygen-containing desorption gas is compressed to a pressure of 0.6 MPa or more. 前記圧力変動吸着式ガス分離工程における前記吸着塔から前記酸素含有脱着ガスを導出するときの当該吸着塔内の減圧と、前記膜式ガス分離工程における前記透過側の前記減圧とは、単一の減圧手段により実現される、請求項１から３のいずれか一つに記載の併行分離方法。   The pressure reduction in the adsorption tower when the oxygen-containing desorption gas is derived from the adsorption tower in the pressure fluctuation adsorption gas separation step and the pressure reduction on the permeate side in the membrane gas separation step are a single The parallel separation method according to claim 1, which is realized by a decompression unit. 酸素および窒素を含む混合ガスから酸素ガスおよび窒素ガスを併行分離するためのシステムであって、
窒素を優先的に吸着するための吸着剤が充填された吸着塔を用いて行う圧力変動吸着式ガス分離法により、前記吸着塔内が相対的に高圧である状態において、前記吸着塔に前記混合ガスを導入して当該混合ガス中の窒素を前記吸着剤に吸着させ、当該吸着塔から酸素富化ガスを導出し、且つ、前記吸着塔内が相対的に低圧である状態において、前記吸着剤から前記窒素を脱着させ、前記吸着塔内に残存する酸素と当該窒素とを含む酸素含有脱着ガスを当該吸着塔から導出するための、圧力変動吸着式ガス分離装置と、
酸素を優先的に透過させるためのガス分離膜を有し、前記酸素含有脱着ガスを、前記ガス分離膜を透過する透過ガスおよび透過しない非透過窒素富化ガスに分離して導出するための、膜式ガス分離器と、
前記膜式ガス分離器の前記ガス分離膜における透過側を大気圧未満の圧力に減圧するための減圧手段と、を備える、酸素ガスおよび窒素ガスの併行分離システム。 A system for concurrently separating oxygen gas and nitrogen gas from a mixed gas containing oxygen and nitrogen,
In the state where the inside of the adsorption tower is at a relatively high pressure, by the pressure fluctuation adsorption gas separation method using an adsorption tower filled with an adsorbent for preferentially adsorbing nitrogen, the mixing is performed in the adsorption tower. In the state where the gas is introduced to adsorb nitrogen in the mixed gas to the adsorbent, the oxygen-enriched gas is led out from the adsorption tower, and the inside of the adsorption tower is at a relatively low pressure. A pressure fluctuation adsorption type gas separation device for desorbing the nitrogen from and deriving an oxygen-containing desorption gas containing oxygen remaining in the adsorption tower and the nitrogen from the adsorption tower;
A gas separation membrane for preferentially permeating oxygen; for separating and deriving the oxygen-containing desorption gas into a permeate gas that permeates the gas separation membrane and a non-permeate nitrogen-enriched gas that does not permeate; A membrane gas separator;
And a decompression means for decompressing a permeation side of the gas separation membrane of the membrane gas separator to a pressure lower than atmospheric pressure. 前記酸素含有脱着ガスが前記膜式ガス分離器に供給される前に当該酸素含有脱着ガスを圧縮するための圧縮手段を更に備える、請求項５に記載の併行分離システム。   The parallel separation system according to claim 5, further comprising compression means for compressing the oxygen-containing desorption gas before the oxygen-containing desorption gas is supplied to the membrane gas separator. 前記減圧手段は、前記圧力変動吸着式ガス分離装置の前記吸着塔から前記酸素含有脱着ガスを導出するときに当該吸着塔内を減圧するための手段としても併せて機能する、請求項５または６に記載の併行分離システム。   The pressure reducing means also functions as a means for decompressing the inside of the adsorption tower when the oxygen-containing desorption gas is led out from the adsorption tower of the pressure fluctuation adsorption gas separation device. The parallel separation system described in 1.
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