JP2003019415A - Method for separating gaseous mixture - Google Patents
Method for separating gaseous mixtureInfo
- Publication number
- JP2003019415A JP2003019415A JP2001206323A JP2001206323A JP2003019415A JP 2003019415 A JP2003019415 A JP 2003019415A JP 2001206323 A JP2001206323 A JP 2001206323A JP 2001206323 A JP2001206323 A JP 2001206323A JP 2003019415 A JP2003019415 A JP 2003019415A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- adsorption tower
- mixed gas
- adsorption
- gaseous mixture
- 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.)
- Pending
Links
Landscapes
- Separation Of Gases By Adsorption (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は混合ガスの分離方法
に関する。さらに詳しくは、吸着剤を充填した２基以上
の吸着塔の一方に混合ガスを加圧下で供給し、それぞれ
の吸着塔で高圧吸着と低圧再生を交互に繰り返して混合
ガスを構成成分ガスに分離する混合ガスの分離方法にお
いて、吸着塔の出口における少なくとも１種類のガスの
濃度をガス濃度検出器により検出し、該ガス濃度検出器
をシーケンサーに連結し、シーケンサーにより吸着塔の
切り替え周期を自動的に変化させて行う混合ガスの分離
方法に関する。TECHNICAL FIELD The present invention relates to a method for separating a mixed gas. More specifically, the mixed gas is supplied under pressure to one of two or more adsorption towers filled with an adsorbent, and high pressure adsorption and low pressure regeneration are alternately repeated in each adsorption tower to separate the mixed gas into constituent gas. In the method for separating mixed gas, the concentration of at least one gas at the outlet of the adsorption tower is detected by a gas concentration detector, the gas concentration detector is connected to a sequencer, and the sequencer automatically switches the adsorption tower switching cycle. The present invention relates to a method for separating a mixed gas by changing the above.
【０００２】[0002]
【従来の技術】近年、半導体製造プロセスなどへ窒素ガ
スの需要が増大しており、かかる窒素ガスを製造する方
法として、分子ふるい炭素などの炭素多孔体を使用して
加圧空気から窒素を分離する圧力スイング吸着法（ＰＳ
Ａ法）が多く実施されている。ＰＳＡ法とは、例えば混
合ガスを空気とした場合、通常２基以上の吸着塔を使用
し、一方の吸着塔に加圧空気を供給して酸素の吸着を行
い、窒素を製品ガスとして取り出すとともに、その間他
方の吸着塔を脱着に付し、複数の吸着塔間で酸素の吸着
と脱着とを交互に繰り返し、分子ふるい炭素による酸素
と窒素の吸着速度の差を利用して連続的に窒素を得る方
法であり、ここに述べた空気からの窒素製造の他、メタ
ノール分解ガスからの水素精製などで実施されている。2. Description of the Related Art In recent years, the demand for nitrogen gas has increased in semiconductor manufacturing processes and the like. As a method for manufacturing such nitrogen gas, nitrogen is separated from pressurized air by using a carbon porous material such as molecular sieving carbon. Pressure swing adsorption method (PS
Method A) is often implemented. In the PSA method, for example, when the mixed gas is air, usually two or more adsorption towers are used, and pressurized air is supplied to one of the adsorption towers to adsorb oxygen, and nitrogen is taken out as a product gas. During that time, the other adsorption tower is subjected to desorption, and the adsorption and desorption of oxygen are alternately repeated among the plurality of adsorption towers, and nitrogen is continuously removed by utilizing the difference in the adsorption rate of oxygen and nitrogen by the molecular sieving carbon. In addition to the production of nitrogen from the air described here, hydrogen purification from methanol decomposition gas is carried out.
【０００３】吸着塔を２基使用して窒素を主成分とする
空気などの混合ガスからＰＳＡ法により酸素を除去し、
製品ガスとして窒素を得る真空再生による従来の方式を
図４により説明する。まず、吸着塔４の吸着工程では、
空気などの原料ガスを原料ガス供給ライン１から導入
し、圧縮機２で圧縮し、冷却器３を通じて吸着塔４へ導
入する。各吸着塔には吸着剤である分子ふるい炭素が充
填されており、原料ガス中の酸素が優先的に吸着剤へ吸
着、除去され、残りの窒素が製品貯槽６へ送られ、製品
ガスライン１７より取り出される。一方の吸着塔が吸着
に付されているとき、他方の吸着塔は脱着工程にあり、
真空ポンプ１９により脱着（再生）に付されている。す
なわち、吸着塔４により吸着が行われているとき、弁
７、１０及び１２は開の状態、弁８、９、１１、１３及
び１４は閉の状態にある。弁１５及び１６については、
脱着工程において脱着に付される吸着塔の圧力が、脱着
工程の初期で大気圧以上の場合、弁１６を閉、弁１５を
開の状態とし、排気ガスライン１８からガスを抜き、脱
着に付される吸着塔の圧力が大気圧付近に下がった時点
で弁１５を閉、弁１６を開の状態とし真空ポンプ１９で
減圧脱着を行い廃棄ガスライン２０より脱着ガスが廃棄
される。By using two adsorption towers, oxygen is removed from a mixed gas containing nitrogen as a main component such as air by the PSA method,
A conventional method by vacuum regeneration for obtaining nitrogen as a product gas will be described with reference to FIG. First, in the adsorption process of the adsorption tower 4,
A raw material gas such as air is introduced from the raw material gas supply line 1, compressed by the compressor 2, and introduced into the adsorption tower 4 through the cooler 3. Each adsorption tower is filled with molecular sieving carbon as an adsorbent, oxygen in the raw material gas is preferentially adsorbed and removed by the adsorbent, and the remaining nitrogen is sent to the product storage tank 6 and the product gas line 17 Taken out. When one adsorption tower is subjected to adsorption, the other adsorption tower is in the desorption process,
It is attached (regenerated) by a vacuum pump 19. That is, when adsorption is performed by the adsorption tower 4, the valves 7, 10 and 12 are open, and the valves 8, 9, 11, 13 and 14 are closed. For valves 15 and 16,
When the pressure of the adsorption tower subjected to desorption in the desorption process is equal to or higher than the atmospheric pressure in the initial stage of the desorption process, the valve 16 is closed and the valve 15 is opened, and the gas is discharged from the exhaust gas line 18 for desorption. When the pressure of the adsorption tower is lowered to around atmospheric pressure, the valve 15 is closed and the valve 16 is opened to perform decompression / desorption with the vacuum pump 19, and the desorbed gas is discarded from the waste gas line 20.
【０００４】所定の時間が経過した後、弁７、１０及び
１２が閉の状態となる。続いての均圧工程では、弁１１
及び１４を開の状態とし、吸着を終えた吸着塔４の残圧
を吸着塔５へ回収する。その後、弁８、９及び１３が開
の状態、弁７、１０、１１、１２及び１４が閉の状態と
なり、吸着塔５が吸着に付され、吸着塔４が脱着に付さ
れる。脱着工程では、吸着塔５の脱着工程と同様に、均
圧工程後の吸着塔４の圧力が大気圧付近までは、弁１６
を閉、弁１５を開の状態とし、排気ガスライン１８から
ガスを抜き、吸着塔４の圧力が大気圧付近に下がった時
点で弁１５を閉、弁１６を開の状態とし真空ポンプ１９
で減圧脱着を行う。吸着塔５の吸着が終わると弁８、９
及び１３を閉とし、弁１１及び１４を開の状態として均
圧工程を行い、吸着塔５の残圧を吸着塔４へ回収する。
上記の操作が定期的に繰り返されて製品窒素が製造され
る。After a predetermined time has elapsed, the valves 7, 10 and 12 are closed. In the subsequent pressure equalizing step, the valve 11
And 14 are opened, and the residual pressure of the adsorption tower 4 after adsorption is recovered to the adsorption tower 5. Thereafter, the valves 8, 9 and 13 are opened, the valves 7, 10, 11, 12 and 14 are closed, the adsorption tower 5 is subjected to adsorption, and the adsorption tower 4 is subjected to desorption. In the desorption process, as in the desorption process of the adsorption tower 5, the valve 16 is used until the pressure of the adsorption tower 4 after the pressure equalization process is close to the atmospheric pressure.
Is closed, the valve 15 is opened, the gas is discharged from the exhaust gas line 18, and when the pressure of the adsorption tower 4 drops to near atmospheric pressure, the valve 15 is closed and the valve 16 is opened.
Depressurize desorption with. When the adsorption of the adsorption tower 5 is completed, the valves 8 and 9
And 13 are closed and the valves 11 and 14 are opened to perform a pressure equalizing step, and the residual pressure of the adsorption tower 5 is recovered in the adsorption tower 4.
The above operation is periodically repeated to produce product nitrogen.
【０００５】これらの弁は、タイマーにより設定された
時間に従って逐次自動的に切り換わるようになってお
り、製品窒素は製品貯槽６に貯蔵され、製品ガス取り出
しライン１７から取り出され、消費される。分子ふるい
炭素に吸着されたガス（酸素）の脱着は、減圧により行
われ、弁９又は１０が開の状態のときに分子ふるい炭素
に吸着されたガスが脱着され、脱着ガスは排気ライン１
８又は廃棄ライン２０から排気される。以上述べたよう
に、従来のＰＳＡ法は、吸着塔の切り替え周期を一定と
して行われるのが通常であるが、これは空気を原料ガス
として使用する場合、ガス組成が一定であり、しかも一
定量で供給することができるからである。These valves are designed so that they are automatically and sequentially switched according to the time set by the timer, and product nitrogen is stored in the product storage tank 6 and taken out from the product gas take-out line 17 and consumed. Desorption of the gas (oxygen) adsorbed on the molecular sieving carbon is performed by depressurization, and the gas adsorbed on the molecular sieving carbon is desorbed when the valve 9 or 10 is open, and the desorbed gas is the exhaust line 1
8 or the waste line 20 is exhausted. As described above, the conventional PSA method is usually carried out with a constant switching period of the adsorption tower. However, when air is used as a raw material gas, the gas composition is constant and a constant amount is used. It can be supplied at.
【０００６】一方、吸着塔の切り替え周期を一定としな
いＰＳＡ法も知られている。例えば、特開昭５４−１６
３７５号公報及び特開昭６０−１９３５２０号公報に、
生成物ガスが一定量に達したとき、次の操作に進むよう
に設定された方法が開示されている。これらの方法は吸
着塔の切り替えを効率的に制御しながらガス分離を行う
ＰＳＡ法であり、エネルギー的に有効なＰＳＡ法である
といえる。しかしながら、これらの方法は、いずれも吸
着剤としてゼオライト系などを使用し、気相における平
衡吸着を利用して分離する場合にのみ実施可能であり、
分子ふるい炭素を使用し、速度分離を利用してＰＳＡ法
を実施する場合は、吸着量、分離能力が経時的に変化
し、適用できない。On the other hand, a PSA method is also known in which the switching cycle of the adsorption tower is not constant. For example, JP-A-54-16
In Japanese Patent Laid-Open No. 375 and Japanese Patent Laid-Open No. 60-193520,
A method is disclosed which is set to proceed to the next operation when the product gas reaches a certain amount. These methods are PSA methods that perform gas separation while efficiently controlling the switching of adsorption towers, and can be said to be energy-effective PSA methods. However, any of these methods can be carried out only when using a zeolite system as an adsorbent and separating using equilibrium adsorption in the gas phase,
When the PSA method is carried out using molecular sieving carbon and utilizing velocity separation, the amount of adsorption and the separation ability change with time and cannot be applied.
【０００７】また、製品ガスの取り出し量が減少したと
きに最適の所要動力で経済的に有利にＰＳＡ方式を制御
する、すなわち、製品ガスの取り出し量に応じて吸着塔
の切り替え周期を変動させるターンダウン制御も知られ
ている。分子ふるい炭素を使用して行うこのような例と
して、例えば、特公平４−６９０８５号公報に、製品窒
素タンクの酸素濃度を検出して吸着塔の切り換え周期
（半サイクル時間）を決定する方法が開示されている。
しかしながら、この方法では吸着塔から出た窒素ガスを
一旦製品窒素タンクに貯蔵するため、急激な流量変動に
よる酸素濃度の変化に対応することができない。Further, when the amount of product gas taken out is reduced, the PSA system is economically controlled with an optimum required power, that is, a turn in which the switching cycle of the adsorption tower is changed according to the amount of product gas taken out. Down control is also known. As such an example using molecular sieving carbon, for example, in Japanese Patent Publication No. 4-69085, there is a method of detecting the oxygen concentration in a product nitrogen tank to determine the switching cycle (half cycle time) of the adsorption tower. It is disclosed.
However, in this method, the nitrogen gas discharged from the adsorption tower is temporarily stored in the product nitrogen tank, and therefore it is not possible to cope with a change in the oxygen concentration due to a sudden change in the flow rate.
【０００８】前述したように、従来のＰＳＡ法は、吸着
塔の切り替え周期を一定にして行われるのが通常である
が、空気を原料ガスとして使用する場合でも原料ガスの
供給量を一定にすることができない場合、また消化ガス
のように、菌や処理物の状態により発生する原料ガスの
組成や供給量を一定にすることができない場合には、吸
着塔の切り替え周期をこれらの変動に追従させて変動さ
せる必要があるが、かかることは現実的ではない。消化
ガスを例にとると、原料ガス中の目的とするガスの濃度
が高い場合は、得られる製品ガス純度も高くなるが、吸
着剤を有効に利用することができない。一方、原料ガス
中の目的とするガスの濃度が低い場合は、得られる製品
ガス純度が低くなる。したがって、原料ガスの組成や供
給量を一定にすることができない場合は、得られた製品
ガスを必要に応じてさらに精製して使用しているのが現
状である。As described above, in the conventional PSA method, the adsorption tower is normally switched at a constant cycle, but the feed amount of the raw material gas is kept constant even when air is used as the raw material gas. If it is not possible, or if it is not possible to make the composition and supply amount of the raw material gas generated depending on the condition of the bacteria and processed materials such as digestion gas, follow the fluctuations in the adsorption tower switching cycle. However, it is not realistic. Taking digestive gas as an example, when the concentration of the target gas in the raw material gas is high, the purity of the product gas obtained is high, but the adsorbent cannot be effectively used. On the other hand, when the concentration of the target gas in the raw material gas is low, the purity of the product gas obtained is low. Therefore, when the composition and supply amount of the raw material gas cannot be made constant, the obtained product gas is further purified and used as needed under the present circumstances.
【０００９】しかしながら、製品ガスをさらに精製する
ことは、設備費及び製造コストの大幅な増加につなが
り、また、操作の面でも煩雑である。また、変動時の製
品ガスの不足分を他のガス源に依存する方法もプロセス
の複雑化、ガス源の補給等から設備費が増加する上、無
人運転で安価なガスを供給できるＰＳＡ法のメリットも
薄れてくる。However, further refining the product gas leads to a large increase in equipment cost and manufacturing cost, and is also complicated in terms of operation. In addition, the method of relying on other gas sources for the shortage of the product gas at the time of fluctuation increases the equipment cost due to the complexity of the process, replenishment of gas sources, etc. The merit will also fade.
【００１０】[0010]
【発明が解決しようとする課題】ＰＳＡ法を効率よく実
施するには、吸着剤の性能向上を図ることが重要である
ことは勿論であるが、如何に低エネルギーで実施するこ
とができるかが、ＰＳＡ法の工業的使命を制するといっ
ても過言ではない。したがって、本発明の目的は、原料
ガスの組成や流量が変動しても容易に追従することがで
き、一定品質の製品ガスを連続的に得ることのできるＰ
ＳＡ法を提供することにある。Needless to say, it is important to improve the performance of the adsorbent in order to efficiently carry out the PSA method, but how low the energy can be carried out is. It is no exaggeration to say that it controls the industrial mission of the PSA Law. Therefore, an object of the present invention is to easily follow up even if the composition and flow rate of the raw material gas fluctuate, and to obtain a product gas of constant quality continuously.
To provide the SA method.
【００１１】[0011]
【課題を解決するための手段】本発明者は、吸着剤を用
いたＰＳＡ法による混合ガスの分離方法において、吸着
塔の出口ガスの濃度に着目して鋭意検討を重ねた結果、
かかるガス濃度を検出して吸着塔の切り替え周期を変化
させることにより、極めて簡単に上記目的を達成するこ
とができることを見出し、本発明に至った。Means for Solving the Problems In the method of separating a mixed gas by the PSA method using an adsorbent, the present inventor has conducted intensive studies by paying attention to the concentration of an outlet gas of an adsorption tower.
The present invention has been found out that the above object can be achieved extremely easily by detecting such a gas concentration and changing the switching cycle of the adsorption tower.
【００１２】すなわち、本発明は、吸着剤を充填した２
基以上の吸着塔の一方に混合ガスを加圧下で供給し、そ
れぞれの吸着塔で高圧吸着と低圧再生を交互に繰り返し
て混合ガスを構成成分ガスに分離する混合ガスの分離方
法において、吸着塔の出口における少なくとも１種類の
ガスの濃度をガス濃度検出器により検出し、該ガス濃度
検出器をシーケンサーに連結し、シーケンサーにより吸
着塔の切り替え周期を自動的に変化させることを特徴と
する混合ガスの分離方法である。That is, according to the present invention, 2 filled with an adsorbent is used.
In the method for separating a mixed gas, the mixed gas is supplied under pressure to one of the above adsorption towers, and high pressure adsorption and low pressure regeneration are alternately repeated in each adsorption tower to separate the mixed gas into constituent gases. Gas concentration of at least one kind of gas at the outlet of the gas is detected by a gas concentration detector, the gas concentration detector is connected to a sequencer, and the sequence of adsorption column switching is automatically changed by the sequencer. Is the method of separation.
【００１３】[0013]
【発明の実施の形態】本発明において、吸着塔には活性
炭、分子ふるい炭素、ゼオライト等の吸着剤が充填され
る。活性炭は木炭、石炭、コークス、やし殻、樹脂、ピ
ッチなどを原料として高温で水蒸気等のガスと反応さ
せ、細孔を発達させた炭素質吸着剤である。分子ふるい
炭素は、３〜５Åの超ミクロ孔が存在し、細孔径が揃っ
た木炭、石炭、コークス、やし殻、樹脂、ピッチなどを
原料として高温で炭化して製造された木質系、石炭系、
樹脂系、ピッチ系などの炭素質材料を細孔調整したもの
からなる吸着剤である。ゼオライトは三次元的な結晶構
造を持つ鉱物系の吸着剤である。かかる吸着剤を目的に
応じ使用し、ＰＳＡ法を実施することにより、混合ガス
から特定のガスを分離することができる。また、本発明
で使用する混合ガスとしてはとくに制限されず、例え
ば、メタンを主成分とした嫌気性発酵の消化ガスなどあ
げることができる。この場合、分子ふるい炭素が好適に
使用可能である。BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an adsorption tower is filled with an adsorbent such as activated carbon, molecular sieving carbon or zeolite. Activated carbon is a carbonaceous adsorbent that has charcoal, coal, coke, coconut shell, resin, pitch, etc. as raw materials and is reacted with a gas such as steam at a high temperature to develop pores. Molecular sieving carbon has charcoal, coal, coke, coconut shell, resin, pitch, etc. with ultra-micro pores of 3 to 5Å and uniform pore size, and is a wood-based coal produced by carbonization at high temperature from raw materials, coal. system,
It is an adsorbent made of resin-based or pitch-based carbonaceous material with fine pores adjusted. Zeolite is a mineral-based adsorbent having a three-dimensional crystal structure. By using such an adsorbent according to the purpose and carrying out the PSA method, a specific gas can be separated from the mixed gas. The mixed gas used in the present invention is not particularly limited, and examples thereof include digestive gas of anaerobic fermentation containing methane as a main component. In this case, molecular sieving carbon can be preferably used.
【００１４】本発明のＰＳＡ法は、とくに原料ガスの組
成や流量が変動しやすい混合ガスから組成が一定の製品
ガスを連続的に製造する場合に好適であり、このような
混合ガスの例として、各種排水、屎尿処理場、下水処理
場、醸造工場、家畜の飼育場などの処理場において生物
学的処理により発生するガス、メタン発酵ガスなどの消
化ガスをあげることができる。以下、原料ガスとしてメ
タンと炭酸ガスを主成分とする混合ガスを使用してメタ
ンを分離する場合について、図により本発明をさらに具
体的に説明する。The PSA method of the present invention is particularly suitable for continuously producing a product gas having a constant composition from a mixed gas in which the composition or flow rate of the raw material gas is likely to change. As an example of such a mixed gas , Various wastewater, human waste treatment plants, sewage treatment plants, breweries, livestock breeding plants, and other treatment plants, and gas generated by biological treatment, digestive gases such as methane fermentation gas. Hereinafter, the present invention will be described in more detail with reference to the drawings in the case where methane is separated using a mixed gas containing methane and carbon dioxide as main components as a raw material gas.
【００１５】図１は、先に図４で説明した従来のＰＳＡ
方式に、炭酸ガス濃度を検出するための炭酸ガス濃度計
と該炭酸ガス濃度計とシーケンサーを連結し、シーケン
サーにより吸着塔の切り替え周期を自動的に変化させて
行うＰＳＡ法の一例を示すフローである。原料ガスであ
る発酵ガスは原料ガス供給ライン１から導入され、圧縮
機２により加圧され、冷却器３によって常温近傍まで冷
却された後、弁７を通って吸着塔４に入り、充填されて
いる分子ふるい炭素によって、吸着されやすい炭酸ガス
等と吸着されにくいメタン等に分離され、分離されたメ
タン等は弁１２を経由し、製品貯槽６に一旦貯蔵された
後、消費される。吸着塔出口における炭酸ガスの濃度は
炭酸ガス濃度検出器２２により瞬時値を絶えず検知す
る。圧縮機として、直流電流を交流電流に変換する、い
わゆるインバータ式の圧縮機を使用してもよい。FIG. 1 shows the conventional PSA described with reference to FIG.
In the flow chart showing an example of the PSA method, a carbon dioxide gas concentration meter for detecting carbon dioxide gas concentration, a carbon dioxide gas concentration meter and a sequencer are connected to the system, and the switching cycle of the adsorption tower is automatically changed by the sequencer. is there. Fermentation gas, which is the raw material gas, is introduced from the raw material gas supply line 1, pressurized by the compressor 2 and cooled to near room temperature by the cooler 3, and then enters the adsorption tower 4 through the valve 7 and is charged. The molecular sieving carbon is separated into carbon dioxide gas which is easily adsorbed and methane which is hard to be adsorbed. The separated methane or the like is stored in the product storage tank 6 through the valve 12 and then consumed. The carbon dioxide concentration at the outlet of the adsorption tower is constantly detected by the carbon dioxide concentration detector 22 as an instantaneous value. As the compressor, a so-called inverter type compressor that converts a direct current into an alternating current may be used.
【００１６】吸着塔の出口において、製品ガス中の炭酸
ガスの濃度が、予め設定された炭酸ガス濃度に達する
と、その信号がシーケンサー２３に伝えられ、吸着工程
が終了する。すなわち、弁７及び１２は閉の状態とな
り、弁１１及び１４を開とする均圧工程を経て、弁１０
及び１３が開の状態となって、脱着操作を終えた吸着塔
５が吸着操作に付される。すなわち、吸着塔の出口ガス
中の炭酸ガスの濃度により、吸着塔の切り替えが行われ
る。一方、吸着を終えた吸着塔４は、弁８及び１５を開
くことにより排気ガスライン１８より大気圧近傍まで減
圧される。必要ならば、この排気ガスは原料ガス側に戻
し、回収を行ってもよい。その後、弁１５を閉じ、弁１
６を開とし分子ふるい炭素に吸着された炭酸ガス等のガ
スを脱着させる脱着操作を行う。以上の発酵ガスを原料
ガスとした場合のＰＳＡ法においては、吸着塔の出口ガ
ス中の炭酸ガスを検出したが、制御しやすいガスを検出
すればよい。When the concentration of carbon dioxide gas in the product gas reaches a preset carbon dioxide concentration at the outlet of the adsorption tower, the signal is transmitted to the sequencer 23, and the adsorption process ends. That is, the valves 7 and 12 are in a closed state, and the valve 10 is subjected to a pressure equalizing process in which the valves 11 and 14 are opened.
The adsorption tower 5 that has completed the desorption operation is subjected to the adsorption operation by opening the and 13 openings. That is, the adsorption tower is switched depending on the concentration of carbon dioxide gas in the outlet gas of the adsorption tower. On the other hand, the adsorption tower 4 that has completed the adsorption is depressurized from the exhaust gas line 18 to near the atmospheric pressure by opening the valves 8 and 15. If necessary, this exhaust gas may be returned to the raw material gas side for recovery. After that, the valve 15 is closed and the valve 1
When 6 is opened, a desorption operation for desorbing a gas such as carbon dioxide gas adsorbed on the molecular sieving carbon is performed. In the PSA method using the above fermentation gas as the raw material gas, carbon dioxide gas was detected in the outlet gas of the adsorption tower, but a gas that is easy to control may be detected.
【００１７】原料ガスの組成や供給量が短時間で急激に
変動する場合、吸着塔の切り替えが頻繁に行われること
になり、製品ガスの回収率が低下する。さらに、エネル
ギー的にも不利である。また、吸着塔を切り替えた直後
は、均圧ガスの影響等で吸着塔出口ガスの濃度が短時間
で変動する場合があり、不用意に切り替えが行われるこ
とになる。したがって、本発明においては、吸着塔の最
低切り替え時間を設定しておくのが好ましい。最低切り
替え時間をあまり短くすると、脱着のための時間が不十
分になるため３０秒以上に設定する必要があり、適用す
るガスやＰＳＡによるが、好ましくは６０秒以上がよ
い。以下、実施例により本発明をさらに具体的に説明す
るが、本発明はこれらに限定されるものではない。When the composition and the supply amount of the raw material gas fluctuate rapidly in a short time, the adsorption towers are frequently switched, and the product gas recovery rate is lowered. Furthermore, it is disadvantageous in terms of energy. Immediately after switching the adsorption tower, the concentration of the gas at the outlet of the adsorption tower may fluctuate in a short time due to the influence of the pressure-equalized gas, etc., and the switching will be performed carelessly. Therefore, in the present invention, it is preferable to set the minimum switching time of the adsorption tower. If the minimum switching time is too short, the time for desorption becomes insufficient, so it is necessary to set it to 30 seconds or longer, and it is preferably 60 seconds or longer, although it depends on the gas and PSA to be applied. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
【００１８】[0018]
【実施例】比較例１
クラレケミカル株式会社製の分子ふるい炭２ＧＮ、１０
Ｌ（リットル）を吸着塔２基に各々充填し、原料ガスと
してメタンと炭酸ガスからなる混合ガスを、供給圧力
０．５ＭＰａ、供給量３．６Ｎｍ３／ｈｒ、脱着工程の
真空度１００Ｔｏｒｒ、吸着塔の切り替え時間１８０
秒、均圧時間５秒の条件で、図４に示すフローに従って
メタンの分離を行った。原料ガスの炭酸ガス濃度を３０
％〜５０％まで変化させ、出口ガス濃度を測定した。結
果を図２に示す。EXAMPLES Comparative Example 1 Molecular sieving coal 2GN, 10 manufactured by Kuraray Chemical Co., Ltd.
L (liter) was filled in each of two adsorption towers, and a mixed gas of methane and carbon dioxide gas was used as a raw material gas, a supply pressure was 0.5 MPa, a supply amount was 3.6 Nm 3 / hr, a vacuum degree in the desorption process was 100 Torr, and adsorption was performed. Tower switching time 180
Second, methane was separated according to the flow shown in FIG. The carbon dioxide concentration of the source gas is 30
% To 50%, and the outlet gas concentration was measured. The results are shown in Figure 2.
【００１９】比較例２
原料ガスの組成をメタン／炭酸ガス＝６０／４０（容量
比）とし、供給量を３Ｎｍ３／ｈｒ〜４Ｎｍ３／ｈｒに
変化させる以外は比較例１と同じ条件でメタンの分離を
行った。結果を図３に示す。Comparative Example 2 Methane was used under the same conditions as Comparative Example 1 except that the composition of the raw material gas was methane / carbon dioxide = 60/40 (volume ratio) and the supply amount was changed from 3 Nm 3 / hr to 4 Nm 3 / hr. Was separated. The results are shown in Fig. 3.
【００２０】実施例１
クラレケミカル株式会社製の分子ふるい炭２ＧＮ、１０
Ｌを吸着塔２基に各々充填し、原料ガスとしてメタンと
炭酸ガスからなる混合ガスを、供給圧力０．５ＭＰａ、
脱着工程の真空度１００Ｔｏｒｒ、均圧時間５秒、吸着
塔の最低切り替え時間３０秒の条件で図１に示すフロー
に従ってメタンの分離を行った。吸着塔出口の炭酸ガス
濃度が１％になった時点で吸着塔が切り換わるように設
定し、原料ガスの炭酸ガス濃度を３０％〜５０％まで変
化させた。結果を図２に示す。Example 1 Molecular sieving coal 2GN, 10 manufactured by Kuraray Chemical Co., Ltd.
L was charged into each of the two adsorption towers, and a mixed gas of methane and carbon dioxide was supplied as a raw material gas at a supply pressure of 0.5 MPa,
Methane was separated according to the flow shown in FIG. 1 under the conditions of a vacuum degree of 100 Torr in the desorption process, a pressure equalization time of 5 seconds, and a minimum adsorption tower switching time of 30 seconds. The adsorption tower was set to be switched when the carbon dioxide concentration at the outlet of the adsorption tower reached 1%, and the carbon dioxide concentration of the raw material gas was changed from 30% to 50%. The results are shown in Figure 2.
【００２１】実施例２
原料ガスの組成をメタン／炭酸ガス＝６０／４０（容量
比）とし、供給量を３Ｎｍ３／ｈｒ〜４Ｎｍ３／ｈｒに
変化させる以外は実施例１と同じ条件でメタンの分離を
行った。結果を図３に示す。Example 2 Methane was produced under the same conditions as in Example 1 except that the composition of the raw material gas was methane / carbon dioxide = 60/40 (volume ratio) and the supply amount was changed from 3 Nm 3 / hr to 4 Nm 3 / hr. Was separated. The results are shown in Fig. 3.
【００２２】以上の結果から、吸着塔の切り替え時間を
固定してＰＳＡ法によりメタンの分離を行うと、原料ガ
ス中の炭酸ガスの濃度が高くなると製品ガス中の炭酸ガ
ス濃度も上昇し、また、原料ガスの供給量が減少すると
メタンの回収率が低下するが、本発明の方法によれば、
製品ガス中の炭酸ガス濃度を低く維持することができ、
メタンの回収率も高いことが明らかである。From the above results, when methane is separated by the PSA method with the adsorption tower switching time fixed, the carbon dioxide concentration in the product gas also rises when the carbon dioxide concentration in the raw material gas increases, and However, when the supply amount of the raw material gas is reduced, the recovery rate of methane decreases, but according to the method of the present invention,
The carbon dioxide concentration in the product gas can be kept low,
It is clear that the recovery rate of methane is also high.
【００２３】[0023]
【発明の効果】本発明により、原料ガスの組成や流量が
変動しても容易に追従することができ、一定品質の製品
ガスを連続的に得ることのできる混合ガスの分離方法を
提供することができる。本発明の方法によれば、消化ガ
スなどのように、菌や処理物の状況によって発生ガスの
組成や流量が変動する場合でも、それに応じて経済的に
有利にＰＳＡ法を実施することができ、産業上の有用性
が大きい。According to the present invention, there is provided a method for separating a mixed gas which can easily follow a composition and flow rate of a raw material gas and continuously obtain a product gas of a constant quality. You can According to the method of the present invention, even when the composition or flow rate of the generated gas varies depending on the conditions of the bacteria or the treated material such as digestion gas, the PSA method can be economically advantageously performed accordingly. , Has great industrial utility.
【図１】本発明の混合ガスの分離方法の一例を示すフロ
ーである。FIG. 1 is a flow showing an example of a mixed gas separation method of the present invention.
【図２】実施例１と比較例１における原料ガス中の炭酸
ガス濃度と製品ガス中の炭酸ガス濃度の関係を示すグラ
フである。FIG. 2 is a graph showing the relationship between the carbon dioxide gas concentration in the raw material gas and the carbon dioxide gas concentration in the product gas in Example 1 and Comparative Example 1.
【図３】実施例２と比較例２における原料ガス供給量と
メタン回収率の関係を示すグラフである。FIG. 3 is a graph showing a relationship between a raw material gas supply amount and a methane recovery rate in Example 2 and Comparative Example 2.
【図４】従来のＰＳＡ方式を示すフローである。FIG. 4 is a flow chart showing a conventional PSA method.
１ … 原料ガス供給ライン ２ … 圧縮機 ３ … 冷却器 ４ … 吸着塔 ５ … 吸着塔 ６ … 製品貯槽 ７〜１６ … 弁 １７ … 製品ガス取り出しライン １８ … 排気ガスライン １９ … 真空ポンプ ２０ … 廃棄ガスライン ２１ … 逆止弁 ２２ … 炭酸ガス濃度計 ２３ … シーケンサー 1 ... Raw material gas supply line 2 ... Compressor 3 ... Cooler 4 ... Adsorption tower 5 ... Adsorption tower 6… Product storage tank 7-16 ... Valve 17… Product gas extraction line 18 ... Exhaust gas line 19 ... Vacuum pump 20 ... Waste gas line 21 ... Check valve 22 ... Carbon dioxide concentration meter 23 ... Sequencer
Claims (4)
方に混合ガスを加圧下で供給し、それぞれの吸着塔で高
圧吸着と低圧再生を交互に繰り返して混合ガスを構成成
分ガスに分離する混合ガスの分離方法において、吸着塔
の出口における少なくとも１種類のガスの濃度をガス濃
度検出器により検出し、該ガス濃度検出器をシーケンサ
ーに連結し、シーケンサーにより吸着塔の切り替え周期
を自動的に変化させることを特徴とする混合ガスの分離
方法。1. A mixed gas is supplied under pressure to one of two or more adsorption towers filled with an adsorbent, and high pressure adsorption and low pressure regeneration are alternately repeated in each adsorption tower to convert the mixed gas into constituent gases. In the method for separating mixed gas to be separated, the concentration of at least one gas at the outlet of the adsorption tower is detected by a gas concentration detector, the gas concentration detector is connected to a sequencer, and the sequencer automatically switches the adsorption tower switching cycle. A method for separating a mixed gas, which comprises changing the gas flow ratio.
ある請求項１記載の混合ガスの分離方法。2. The method for separating a mixed gas according to claim 1, wherein a switching cycle of the adsorption tower is 30 seconds or more.
とする混合ガスである請求項１又は２記載の混合ガスの
分離方法。3. The method for separating a mixed gas according to claim 1, wherein the mixed gas is a mixed gas containing methane and carbon dioxide as main components.
ずれかに記載の混合ガスの分離方法。4. The method for separating a mixed gas according to claim 1, wherein the mixed gas is digestion.
Priority Applications (1)
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|---|---|---|---|
| JP2001206323A JP2003019415A (en) | 2001-07-06 | 2001-07-06 | Method for separating gaseous mixture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001206323A JP2003019415A (en) | 2001-07-06 | 2001-07-06 | Method for separating gaseous mixture |
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| Publication Number | Publication Date |
|---|---|
| JP2003019415A true JP2003019415A (en) | 2003-01-21 |
Family
ID=19042481
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001206323A Pending JP2003019415A (en) | 2001-07-06 | 2001-07-06 | Method for separating gaseous mixture |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006212524A (en) * | 2005-02-02 | 2006-08-17 | Mitsubishi Heavy Ind Ltd | Composite incineration system and method for waste |
| JP2010209036A (en) * | 2009-03-12 | 2010-09-24 | Taiyo Nippon Sanso Corp | Methane concentration method |
| JP2012025729A (en) * | 2010-06-21 | 2012-02-09 | Sumitomo Seika Chem Co Ltd | Method and apparatus for purifying propane |
| JP2014073461A (en) * | 2012-10-04 | 2014-04-24 | Metawater Co Ltd | Method for refining mixed gas and refining equipment |
| US9732297B2 (en) | 2013-03-19 | 2017-08-15 | Osaka Gas Co., Ltd. | Gas purification method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2006212524A (en) * | 2005-02-02 | 2006-08-17 | Mitsubishi Heavy Ind Ltd | Composite incineration system and method for waste |
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| JP2012025729A (en) * | 2010-06-21 | 2012-02-09 | Sumitomo Seika Chem Co Ltd | Method and apparatus for purifying propane |
| JP2014073461A (en) * | 2012-10-04 | 2014-04-24 | Metawater Co Ltd | Method for refining mixed gas and refining equipment |
| US9732297B2 (en) | 2013-03-19 | 2017-08-15 | Osaka Gas Co., Ltd. | Gas purification method |
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