JP3874185B2

JP3874185B2 - Organic solvent processing equipment

Info

Publication number: JP3874185B2
Application number: JP2002268906A
Authority: JP
Inventors: 友明池野
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2002-09-13
Filing date: 2002-09-13
Publication date: 2007-01-31
Anticipated expiration: 2022-09-13
Also published as: JP2004105806A

Description

【０００１】
【発明が属する技術分野】
本発明は、大気への有機溶剤の飛散を最小限として、有機溶剤を最大限に回収することを可能とした有機溶剤処理装置に関するものである。
【０００２】
【従来の技術】
近年、有害大気汚染物質に対する排出濃度規制が強化されてきており、有機溶剤処理装置からの排ガス中の有機溶剤濃度を最大限に低減することが望まれている。
【０００３】
従来、上記処理装置には吸着材として活性炭素繊維や粒状活性炭が充填されている吸着槽が２基以上設けられている他に、各吸着槽に対する有機溶剤が含有した被処理ガスを供給する手段と水蒸気を噴出する脱着手段とを設け、前記吸着槽にて被処理ガスを吸着処理する吸着工程と脱着手段にて脱着を行う脱着工程とを交互に切り替える手段が設けて構成してあった。
【０００４】
吸着に関与する細孔が粒状活性炭ではマクロポアであるのに対し活性炭素繊維ではミクロポアであることなどから、有機溶剤の吸着・脱着速度が活性炭素繊維の方が速く、また脱着時間が短時間で終了するため回収溶剤の品質が良いことが挙げられる。また、吸着材を水蒸気にて脱着を行うと、一旦吸着材が湿ることにより、吸着性能を長期間の運転において維持するには吸着材を次の脱着までに乾燥させる必要がある。この乾燥が不十分であると運転が進むに連れ吸着材の湿る部分が広がり、吸着性能を大幅に低下させる。活性炭素繊維は粒状活性炭に比べ乾燥が極めて速く行われることから、吸着工程が乾燥を兼ねるケースが一般的であった。
【０００５】
しかしながら、被処理ガスの有機溶剤濃度が増すに連れ、処理風量当たりの吸着材が多くなることから、乾燥を吸着工程で兼ねることは困難となっていき、下記の様々な対策が取られてきた。
（１）単独にて乾燥工程を設ける：乾燥用の吸着槽をもう１槽追加する必要があることから、装置が大型化となる上、処理系統が複雑になる問題がある。
（２）被処理ガスの吸着前温度を上げる（特許文献１参照）：吸着温度を上げるに従い、吸着効率が低下する問題がある。
（３）被処理ガスの吸着前相対湿度を下げる：水分除去の付属装置が必要である。
（４）被処理ガスを希釈して風量を増加させる（特許文献１参照）：吸着する有機溶剤濃度が下がるため、吸着効率も下がる。
【０００６】
これらの対策を行っても、吸着工程特に吸着初期においては乾燥が十分でなく、吸着材が湿っており高温であることから吸着能力が完全に回復していないため処理済ガス中に有機溶剤が漏れだすことがあった。また、吸着材の取付部の隙間や充填による隙間が極微量ではあるが発生するため、これらの隙間から被処理ガスが漏れ出すなどにより、１段のみの吸着工程での除去性能は９８〜９９％が限界となり、さらに除去性能を高めるには直列接続の多段吸着処理を行う必要があった。
【０００７】
【特許文献１】
特開昭６１−３５８２２
【０００８】
【発明が解決しようとする課題】
近年の環境認識の向上に伴い、排出ガス中の有機溶剤含有量の規制が強化されたことから、有機溶剤含有量の低減化が活発となって来ている。被処理ガスの有機溶剤濃度が高濃度の場合においては、除去性能が９９％以上を求められるため、直列多段処理を行うケースが増して来ている。直列多段処理の順序としては、被処理ガスを最初に吸着処理する１段目の工程を第１吸着工程とし、その後に処理効率の要求レベルが上がるに従い処理経路に直列に接続された吸着処理工程を２段目（第２吸着工程）、３段目（第３吸着工程）と増していくことになる。尚、脱着効率を落とさないために、脱着は吸着処理の１段目である第１吸着工程が終了した後に行うことが最良であり、直列２段吸着処理の例に取ると、特定の吸着槽での処理サイクルは脱着→第２吸着工程→第１吸着工程→脱着となる。
【０００９】
しかし、直列２段以上の処理の場合、第１吸着工程では高濃度有機溶剤の吸着熱により、吸着材に吸着していた水分が蒸発し、この水分が次工程の第２吸着工程に移り、第２吸着工程での乾燥を阻害させてしまう。さらに、この水分が第１吸着工程と第２吸着工程との間で循環し、最終的には吸着材の乾燥不良となり、吸着材が湿りだし最終的には濡れることにより吸着効率が大幅に低下する。
【００１０】
この吸着熱は有機溶剤濃度に比例することから、濃度が高ければ高い程吸着熱の発生量が増し、吸着材の温度上昇、処理済ガスの温度上昇、及び水分の蒸発などが発生するため、第１吸着工程の吸着材の吸着効率を低下させるだけでなく、後工程である第２吸着工程へ悪影響を及ぼすことを考慮して細心の注意を払って装置設計に取り組む必要があった。また、被処理ガスが高濃度で低風量の場合に顕著となる。吸着熱の発生を抑制する方法としては、被処理ガスの有機溶剤濃度を希釈などにより下げる方法があるが、吸着濃度が下がることにより吸着効率も低下することから吸着材量を多くしなければならず、装置が大型化となり、コスト及び設置場所などにおいて問題となっていた。
【００１１】
最近、第１吸着工程と第２吸着工程との間に第１吸着工程から飛散した水分を冷却・加熱機構により除去する方法（特開２００１−１７９０４１）が実施されているが、水分を凝縮させるには露点まで冷却に必要なエネルギー及び加熱に必要なエネルギーは処理済ガスの風量に比例していくことから、ランニングコストの面で問題であった。
【００１２】
本発明は高濃度処理において、第１吸着工程での吸着熱による水分蒸発に対する次工程の第２吸着工程への影響を阻止し、高処理性能を維持することが出来る有機溶剤処理装置を提供するものである。
【００１３】
【課題を解決するための手段】
即ち、本発明は高濃度処理での多段直列処理方式において、第１吸着工程から高濃度有機溶剤の被処理ガスの吸着処理での吸着熱にて蒸発した水分により後工程の第２吸着工程で乾燥不足とならないように、第２吸着工程前において第２吸着工程に入る処理済ガスを外気により希釈し風量を増すことにより、吸着材の湿りを防ぐことである。
【００１４】
高濃度有機溶剤の被処理ガスを直列多段吸着にて処理を行う場合、まず最初に１段目の第１吸着工程に高濃度有機溶剤の被処理ガスを通すと、高濃度の有機溶剤を吸着させることにより、吸着熱が発生する。吸着熱の発生により吸着材に吸着していた水分が蒸発を行うと共に吸着材だけでなく出口の処理済ガスの温度をも上昇させる。第２吸着工程に入る第１吸着工程の処理済ガスを外気にて希釈することにより風量を増加せしめるとともに相対湿度が下げることにより第２吸着工程での希釈後の処理済ガスによる乾燥を強化させる。
【００１５】
さらに、外気の温度が低い冬場又は外気の相対湿度が高い雨天時や夏場において外気を加熱することにより、年間を通して第２吸着工程の乾燥条件を安定させることが出来る。
【００１６】
第１吸着工程の処理済ガスと外気との混合割合は吸着材の量、ガス成分の種類、処理済ガスの風量、温湿度等によって適宜決定される。例えば、吸着材の量に対して処理済ガスの風量が少ない場合や処理済ガスの温湿度が高い場合には外気の混合割合を増やしていき、第２吸着工程終了迄に吸着材を乾燥させる。
【００１７】
この結果、本発明のシステムは連続的に高濃度有機溶剤含有ガスを高効率に除去することが可能となり非常に操作性に優れるとともに、長期間にわたっての高性能を維持することが可能となった。
【００１８】
【発明の実施の形態】
本発明の一実施形態を図１にて説明する。有機溶剤含有ガスＡは送風機１にて自動ダンパー１１の開閉により第１吸着工程となっている吸着槽２に送られ、有機溶剤は吸着槽２内の吸着材を通過中に吸着されて被処理ガスとなって排出される。しかしこの被処理ガス中には第１吸着工程で漏れだした有機溶剤が含まれていることから、さらに吸着処理を行うため、第２吸着工程へ送風機５にて送られ、第２吸着工程にて処理後清浄ガスとなって系外へ排出される。第２吸着工程後、第１吸着工程が終了した吸着槽は脱着工程に切り替わり自動ダンパー１１で封鎖され、吸着槽２内に水蒸気を噴出して、すでに吸着材に吸着された有機溶剤を脱着する。脱着された有機溶剤と水蒸気はコンデンサー６に送られて凝縮し、凝縮した有機溶剤は回収溶剤として得られる。
【００１９】
有機溶剤含有ガスＡ（被処理ガス）が高濃度である場合、第１吸着工程において高濃度の有機溶剤の吸着により多量の吸着熱が発生し、吸着材に吸着していた水分が蒸発を行うと共に吸着材だけでなく出口の処理済ガスの温度をも上昇させる。第１吸着工程の出口の処理済ガスを外気により希釈を行うことにより、第２吸着工程に流れる被処理ガスの風量を増し、第２吸着工程での希釈後の処理済ガスによる乾燥を強化させる。
【００２０】
さらに乾燥を強化させるには、外気を加熱手段４により昇温し、第２吸着工程の吸着材の乾燥を大幅に促進させる。加熱温度上昇幅としては、＋５〜＋１５℃内が望ましい。
【００２１】
第１吸着工程と第２吸着工程間で処理済ガスを外気によて希釈を行うことにより、第１吸着工程からの水分蒸発による吸着材の湿りを防止したものである。この結果、長期間の連続運転においても、常時系外に排出されるガス濃度は低濃度でかつ一定化することが可能となった。
【００２２】
【実施例】
図１に示す有機溶剤処理装置を基本フローとして、以下に活性炭素繊維を吸着材として使用した有機溶剤処理装置での実施例を示す。［実施例１］塩化メチレンを１００００ｐｐｍ含む４０℃の溶剤混合ガスを、風量７０Ｎｍ³／分で送風機１、吸着槽２、外気導入、送風機５、吸着槽２の順に流し被処理ガスの吸着処理を行った。吸着時間８分間及び脱着時間６分間にて切替を行い、脱着された塩化メチレンと水蒸気はコンデンサー６へ送られ、コンデンサー７にて凝縮し、塩化メチレンを回収した。
【００２３】
外気を３０Ｎｍ³／分導入により第２吸着工程入口の処理ガスの風量が１００Ｎｍ³／分、温度が３７℃、露点２０℃となり、第１吸着工程出口中の塩化メチレン出口濃度は平均１８０ppm（除去率９８．２％）、第２吸着工程出口中の塩化メチレン出口濃度は平均１２ppm（除去率９0.5％）となった。
【００２４】
［実施例２］塩化メチレンを１００００ｐｐｍ含む４０℃の溶剤混合ガスを、風量７０Ｎｍ³／分で送風機１、吸着槽２、外気導入と加熱手段４、送風機５、吸着槽２の順に流し被処理ガスの吸着処理を行った。吸着時間８分間及び脱着時間６分間にて切替を行い、脱着された塩化メチレンと水蒸気はコンデンサー６へ送られ、コンデンサー７にて凝縮し、塩化メチレンを回収した。
【００２５】
外気を３０Ｎｍ³／分導入すると共に、加熱手段により２５℃から３５℃に昇温することにより、第２吸着工程入口の処理ガスは風量が１００Ｎｍ³／分、温度が４０℃、露点２０℃となり、第１吸着工程出口中の塩化メチレン出口濃度は平均１４０ppm（除去率９８．６％）、第２吸着工程出口中の塩化メチレン出口濃度は平均５ppm（除去率９４．９％）となった。
【００２６】
［比較例］塩化メチレンを１００００ｐｐｍ含む４０℃の溶剤混合ガスを、風量７０Ｎｍ³／分で送風機１、吸着槽２、送風機５、吸着槽２の順に流し被処理ガスの吸着処理を行った。吸着時間８分間及び脱着時間６分間にて切替を行い、脱着された塩化メチレンと水蒸気はコンデンサー６へ送られ、コンデンサー６にて凝縮し、塩化メチレンを回収した。
【００２７】
加熱手段及び冷却手段が無く第１吸着工程出口の処理済ガスを４１℃と上昇し、第１吸着工程出口中の塩化メチレン出口濃度は平均８００ｐｐｍ（除去率９２．０％）、第２吸着工程出口中の塩化メチレン出口濃度は平均９０ｐｐｍ（除去率８８．８％）となった。
【００２８】
実施例１、実施例２、比較例の処理結果を下記の表１に示す。
【表１】

【００２９】
【発明の効果】
以上の様に本発明の有機溶剤処理装置によれば、高濃度による直列多段吸着処理において、第１吸着工程と第２吸着工程との間に処理ガスを外気にて希釈を行うことにより、第１吸着工程での高濃度吸着による吸着熱にて飛散する水分に対して、第２吸着工程に流れる希釈後の処理ガスの風量を増し、相対湿度を下げて、吸着材の乾燥を十分に行うことにより、連続的に安定な高除去の処理が行える。
【図面の簡単な説明】
【図１】有機溶剤処理装置の実施例の基本処理フロー図
【図２】有機溶剤処理装置の比較例の基本処理フロー図
【符号の説明】
１：送風機
２：吸着槽
３：外気導入フィルター
４：加熱手段
５：送風機
６：コンデンサー
１１：自動ダンパー
１２：水蒸気弁
１３：脱着ガス弁
Ａ：有機溶剤被処理ガス
Ｂ：第１吸着工程出口ガス
Ｃ：第２吸着工程入口ガス
Ｄ：清浄ガス
Ｅ：外気[0001]
[Technical field to which the invention belongs]
The present invention relates to an organic solvent processing apparatus capable of maximally recovering an organic solvent while minimizing the scattering of the organic solvent to the atmosphere.
[0002]
[Prior art]
In recent years, emission concentration regulations for harmful air pollutants have been strengthened, and it is desired to reduce the organic solvent concentration in the exhaust gas from the organic solvent treatment apparatus to the maximum.
[0003]
Conventionally, the treatment apparatus is provided with two or more adsorption tanks filled with activated carbon fibers or granular activated carbon as an adsorbent, and means for supplying a gas to be treated containing an organic solvent for each adsorption tank And a desorption means for ejecting water vapor, and a means for alternately switching between an adsorption process for adsorbing the gas to be treated in the adsorption tank and a desorption process for desorption by the desorption means.
[0004]
The pores involved in adsorption are macropores in granular activated carbon, but micropores in activated carbon fiber. Therefore, the adsorption and desorption rate of organic solvents is faster with activated carbon fiber, and the desorption time is shorter. Since the process is completed, the quality of the recovered solvent is good. Further, when the adsorbent is desorbed with water vapor, the adsorbent is once moistened, so that it is necessary to dry the adsorbent before the next desorption in order to maintain the adsorption performance in a long-term operation. If this drying is insufficient, as the operation proceeds, the portion of the adsorbent that gets wet spreads and the adsorption performance is greatly reduced. Since activated carbon fibers are dried much faster than granular activated carbon, the case where the adsorption process also serves as a drying is common.
[0005]
However, As the increasing organic solvent concentration of the gas to be treated, since it becomes large adsorbent per treatment air volume, it also serves as a drying adsorption step will become difficult, various measures below have been taken .
(1) Providing a drying step alone: Since it is necessary to add another drying adsorption tank, there is a problem that the apparatus becomes large and the processing system becomes complicated.
(2) Raising the pre-adsorption temperature of the gas to be treated (see Patent Document 1): There is a problem that the adsorption efficiency decreases as the adsorption temperature is raised.
(3) Lowering the relative humidity before adsorption of the gas to be treated: A water removal accessory is required.
(4) Increasing the air volume by diluting the gas to be treated (see Patent Document 1): Since the concentration of the adsorbed organic solvent is lowered, the adsorption efficiency is also lowered.
[0006]
Even if these measures are taken, drying is not sufficient in the adsorption process, particularly in the early stage of adsorption, and the adsorption capacity is not completely recovered because the adsorbent is moist and high temperature. There was a leak. Further, since the gap between the adsorbent attachment portions and the gap due to filling is generated in a very small amount, the removal performance in only one stage of the adsorption process is 98 to 99 due to leakage of the gas to be treated from these gaps. % Was the limit, and in order to further improve the removal performance, it was necessary to perform a multi-stage adsorption treatment connected in series.
[0007]
[Patent Document 1]
JP 61-35822 A
[0008]
[Problems to be solved by the invention]
With the recent improvement in environmental awareness, regulations on the content of organic solvents in exhaust gas have been strengthened, so that the reduction of organic solvent content has become active. When the concentration of the organic solvent in the gas to be treated is high, the removal performance is required to be 99% or more, and therefore, the number of cases where serial multistage treatment is performed is increasing. As the order of the serial multi-stage treatment, the first stage process for first subjecting the gas to be treated to adsorption is the first adsorption process, and then the adsorption treatment process connected in series to the treatment path as the required level of treatment efficiency increases. Are increased to the second stage (second adsorption process) and the third stage (third adsorption process). In order not to reduce the desorption efficiency, it is best to perform desorption after the completion of the first adsorption process, which is the first stage of the adsorption process. In the example of the series two-stage adsorption process, a specific adsorption tank is used. The treatment cycle is as follows: desorption → second adsorption step → first adsorption step → desorption.
[0009]
However, in the case of the treatment of two or more stages in series, the moisture adsorbed on the adsorbent is evaporated by the adsorption heat of the high concentration organic solvent in the first adsorption step, and this moisture moves to the second adsorption step of the next step, The drying in the second adsorption process is hindered. Furthermore, this moisture circulates between the first adsorption step and the second adsorption step, eventually resulting in poor drying of the adsorbent, and the adsorbent begins to get wet and eventually gets wet, greatly reducing the adsorption efficiency. To do.
[0010]
Since this adsorption heat is proportional to the concentration of the organic solvent, the higher the concentration, the greater the amount of heat generated, causing the temperature of the adsorbent to rise, the temperature of the treated gas to rise, and the evaporation of moisture. In addition to lowering the adsorption efficiency of the adsorbent in the first adsorption process, it was necessary to pay close attention to the device design in consideration of adverse effects on the second adsorption process, which is a subsequent process. Moreover, it becomes remarkable when the gas to be treated has a high concentration and a low air volume. As a method of suppressing the generation of heat of adsorption, there is a method of lowering the organic solvent concentration of the gas to be treated by dilution or the like. However, since the adsorption efficiency is lowered by lowering the adsorption concentration, the amount of adsorbent must be increased. However, the size of the apparatus has increased, which has been a problem in terms of cost and installation location.
[0011]
Recently, a method (Japanese Patent Laid-Open No. 2001-179041) for removing moisture scattered from the first adsorption step by the cooling / heating mechanism between the first adsorption step and the second adsorption step has been implemented. However, the energy required for cooling to the dew point and the energy required for heating are proportional to the air volume of the treated gas, which is a problem in terms of running cost.
[0012]
The present invention provides an organic solvent treatment apparatus capable of preventing the influence of the next adsorption step on the water evaporation due to the heat of adsorption in the first adsorption step in the high concentration treatment and maintaining high treatment performance. Is.
[0013]
[Means for Solving the Problems]
That is, according to the present invention, in the multi-stage serial processing system in the high concentration treatment, the water evaporated from the adsorption heat in the adsorption treatment of the gas to be treated of the high concentration organic solvent from the first adsorption step is used in the second adsorption step in the subsequent step. In order to prevent drying shortage, the treated gas entering the second adsorption step is diluted with outside air before the second adsorption step to increase the air volume, thereby preventing the adsorbent from getting wet.
[0014]
When processing high concentration organic solvent gas by serial multistage adsorption, first pass the high concentration organic solvent gas to the first adsorption process of the first stage, and the high concentration organic solvent is adsorbed. By doing so, heat of adsorption is generated. Moisture adsorbed on the adsorbent due to the generation of heat of adsorption evaporates and raises the temperature of the treated gas at the outlet as well as the adsorbent. By diluting the treated gas of the first adsorption step entering the second adsorption step with outside air, the air volume is increased and the relative humidity is lowered to enhance the drying by the treated gas after dilution in the second adsorption step. .
[0015]
Furthermore, the drying conditions of the second adsorption step can be stabilized throughout the year by heating the outside air in the winter when the temperature of the outside air is low or in the rainy weather or summer when the relative humidity of the outside air is high.
[0016]
The mixing ratio of the treated gas and the outside air in the first adsorption step is appropriately determined depending on the amount of the adsorbent, the type of gas component, the volume of the treated gas, the temperature and humidity, and the like. For example, when the air volume of the treated gas is small relative to the amount of the adsorbent or when the temperature and humidity of the treated gas are high, the mixing ratio of the outside air is increased and the adsorbent is dried before the end of the second adsorption process. .
[0017]
As a result, the system of the present invention can continuously remove a high-concentration organic solvent-containing gas with high efficiency, and is extremely excellent in operability and can maintain high performance over a long period of time. .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. The organic solvent-containing gas A is sent to the adsorption tank 2 which is the first adsorption process by opening and closing the automatic damper 11 by the blower 1, and the organic solvent is adsorbed while passing through the adsorbent in the adsorption tank 2 to be processed. It is discharged as gas. However, since the organic solvent leaked in the first adsorption process is contained in the gas to be treated, the blower 5 sends the second adsorption process to the second adsorption process for further adsorption treatment. After the treatment, it becomes clean gas and is discharged outside the system. After the second adsorption process, the adsorption tank in which the first adsorption process is completed is switched to the desorption process, blocked by the automatic damper 11, and water vapor is ejected into the adsorption tank 2 to desorb the organic solvent already adsorbed by the adsorbent. . The desorbed organic solvent and water vapor are sent to the condenser 6 and condensed, and the condensed organic solvent is obtained as a recovery solvent.
[0019]
When the organic solvent-containing gas A (treated gas) has a high concentration, a large amount of heat of adsorption is generated by the adsorption of the high concentration organic solvent in the first adsorption step, and the water adsorbed on the adsorbent is evaporated. At the same time, the temperature of the treated gas at the outlet as well as the adsorbent is increased. By diluting the treated gas at the outlet of the first adsorption process with outside air, the air volume of the gas to be treated flowing into the second adsorption process is increased, and the drying by the treated gas after dilution in the second adsorption process is enhanced. .
[0020]
In order to further enhance the drying, the temperature of the outside air is raised by the heating means 4 to greatly accelerate the drying of the adsorbent in the second adsorption step. The heating temperature rise is preferably within the range of +5 to + 15 ° C.
[0021]
The treated gas is diluted with the outside air between the first adsorption step and the second adsorption step, thereby preventing the adsorbent from getting wet due to moisture evaporation from the first adsorption step. As a result, even during long-term continuous operation, the concentration of gas discharged out of the system at all times can be kept low and constant.
[0022]
【Example】
The organic solvent processing apparatus shown in FIG. 1 is used as a basic flow, and an example of an organic solvent processing apparatus using activated carbon fibers as an adsorbent will be described below. [Example 1] A 40 ° C solvent mixed gas containing 10000 ppm of methylene chloride was flowed in the order of blower 1, adsorption tank 2, outside air introduction, blower 5 and adsorption tank 2 in this order at an air volume of 70 Nm ³ / min. went. Switching was performed at an adsorption time of 8 minutes and a desorption time of 6 minutes, and the desorbed methylene chloride and water vapor were sent to the condenser 6, condensed in the condenser 7, and methylene chloride was recovered.
[0023]
Outside air 30 Nm ³ / min introduced by airflow in the second adsorption step the inlet of process gas 100 Nm ³ / min, temperature of 37 ° C., a dew point of 20 ° C., and the methylene outlet chloride concentration of the first in the adsorption step outlet average 180 ppm (removal The rate at which the methylene chloride exited the second adsorption step was 12 ppm on average (removal rate 90.5%).
[0024]
[Example 2] A solvent mixed gas containing 10000 ppm of methylene chloride was passed through the blower 1, the adsorption tank 2, the outside air introduction and heating means 4, the blower 5, and the adsorption tank 2 in this order at a flow rate of 70 Nm ³ / min. The adsorption process was performed. Switching was performed at an adsorption time of 8 minutes and a desorption time of 6 minutes, and the desorbed methylene chloride and water vapor were sent to the condenser 6, condensed in the condenser 7, and methylene chloride was recovered.
[0025]
By introducing outside air at 30 Nm ³ / min and heating from 25 ° C. to 35 ° C. by the heating means, the processing gas at the second adsorption step inlet has an air volume of 100 Nm ³ / min, a temperature of 40 ° C., and a dew point of 20 ° C. The methylene chloride outlet concentration in the first adsorption step outlet averaged 140 ppm (removal rate 98.6%), and the methylene chloride outlet concentration in the second adsorption step outlet averaged 5 ppm (removal rate 94.9%).
[0026]
[Comparative Example] A solvent mixed gas containing 10000 ppm of methylene chloride was passed through the blower 1, the adsorption tank 2, the blower 5, and the adsorption tank 2 in this order at an air volume of 70 Nm ³ / min to carry out the adsorption treatment of the gas to be treated. Switching was performed at an adsorption time of 8 minutes and a desorption time of 6 minutes, and the desorbed methylene chloride and water vapor were sent to the condenser 6 and condensed in the condenser 6 to recover methylene chloride.
[0027]
Without the heating means and the cooling means, the treated gas at the outlet of the first adsorption process is raised to 41 ° C., the concentration of methylene chloride at the outlet of the first adsorption process is 800 ppm on average (removal rate 92.0%), the second adsorption process The outlet concentration of methylene chloride in the outlet averaged 90 ppm (removal rate 88.8%).
[0028]
The processing results of Example 1, Example 2, and Comparative Example are shown in Table 1 below.
[Table 1]

[0029]
【The invention's effect】
As described above, according to the organic solvent treatment apparatus of the present invention, in the serial multistage adsorption treatment with high concentration, the treatment gas is diluted with the outside air between the first adsorption step and the second adsorption step, For the moisture scattered by the heat of adsorption due to the high concentration adsorption in the first adsorption process, the air volume of the diluted process gas flowing in the second adsorption process is increased, the relative humidity is lowered, and the adsorbent is sufficiently dried. As a result, a continuous and stable high removal process can be performed.
[Brief description of the drawings]
FIG. 1 is a basic process flow diagram of an embodiment of an organic solvent treatment apparatus. FIG. 2 is a basic process flow chart of a comparative example of an organic solvent treatment apparatus.
1: Blower 2: Adsorption tank 3: Outside air introduction filter 4: Heating means 5: Blower 6: Condenser 11: Automatic damper 12: Water vapor valve 13: Desorption gas valve A: Organic solvent treated gas B: First adsorption process outlet gas C: Second adsorption process inlet gas D: Clean gas E: Outside air

Claims

Using an organic solvent processing apparatus having an adsorption tank that adsorbs a gas to be treated with an adsorbent, the organic solvent contained in the organic solvent-containing gas is a first-stage adsorption tank in a series two-stage or more series multi-stage adsorption system. In-line multistage adsorption type organic solvent treatment, characterized in that means for increasing the air volume by diluting the first stage treated gas with outside air before the second stage treatment is provided between the first stage and the second stage adsorption tank apparatus.

2. The organic solvent treatment apparatus according to claim 1, further comprising a heating mechanism for controlling the relative humidity of the outside air to be used for dilution by a heating means.

The organic solvent treatment apparatus according to claim 1 or 2, wherein the adsorbent is activated carbon fiber or granular activated carbon.