JP3922449B2

JP3922449B2 - Organic solvent recovery system

Info

Publication number: JP3922449B2
Application number: JP2002286631A
Authority: JP
Inventors: 学浅野
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2002-09-30
Filing date: 2002-09-30
Publication date: 2007-05-30
Anticipated expiration: 2022-09-30
Also published as: JP2004121921A

Description

【０００１】
【発明の属する技術分野】
本発明は、有機溶剤含有ガスを処理する方法に関し、殊に排気ガスの有機溶剤濃度を低減するための処理システム及び方法に関する。
【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、有機溶剤含有ガス処理装置からの排ガス濃度を低減することが望まれている。
【０００３】
従来、上記のガス処理装置としては例えば活性炭素繊維材で有機溶剤含有ガス（被処理ガス）中の有機溶剤を吸着する一対の吸着槽と、各吸着槽に対する被処理ガス供給手段と脱着用ガス供給手段を設け、前記吸着吸着槽に被処理ガスを供給する吸着処理状態と、脱着用ガスを供給する脱着処理状態とに切り換える切り換え手段を設けて構成してあったが、さらに吸着後の排ガス濃度を低減し、しかも有機溶剤の回収効率を向上させるために、特許文献１では３個以上の吸着槽を設け、前記３個以上の吸着槽の内の複数の吸着槽が直列接続されて吸着処理状態になり、前記３個以上の吸着槽の内の少なくとも１個の吸着槽が脱着処理状態になるよう構成構成するとともに、前記脱着処理状態にある少なくとも１個の吸着槽は脱着処理状態に切り換えられる前において、前記複数の直列吸着状態の内の上手側に位置する吸着槽であるよう構成してある装置が提案されている。即ち、脱着処理後の有機溶剤成分の少ない吸着槽を複数の直列吸着槽の下手側に配し、バックアップとすることにより排気ガス中の有機溶剤濃度を安定的に低く抑えるものである。
【０００４】
しかしながら、前記装置で有機溶剤を回収する場合の脱着処理は通常、スチームによって行うのでバックアップとなる下手側の吸着槽の吸着材は吸着処理工程に切り換わり後には、高温でしかも湿潤状態にあり、吸着初期には吸着材中の有機溶剤の微少な残存成分が吸着ガスによって押し出されたり、吸着材の湿りによって吸着効率が低下したり吸着ガスが素抜けたりし易い。
【０００５】
特に、直列吸着によるバックアップ処理を行う場合は通常、被処理ガス濃度が数千〜数万ｐｐｍの高濃度であることと、直列の２回吸着であることから、脱着処理前の吸着材中の吸着量は低濃度、一段吸着処理の場合に比べて多く、前記押し出しによる排気濃度上昇が顕著になる。
【０００６】
また、沸点が低く活性炭素材への吸着性が低い溶剤や水溶性の溶剤の場合は、吸着材の湿りによる吸着効率の低下や素抜けの程度が大きく、下手側のバックアップ槽にて処理後の排ガスであっても、脱着処理から切り換わり直後の吸着初期に、排気濃度が高くなる程度が大きく、排出濃度基準が非常に厳しい場合は要求を満足できなくなる。
【０００７】
さらに、特許文献２では、環境への有機溶剤の拡散をできるだけ低減する目的で、被処理ガスの吸着とスチームによる脱着をバッチ処理で行う溶剤回収装置において、前記有機溶剤回収装置から排出される処理済ガスを、吸着材を担持したハニカム構造の管状孔を有機溶剤含有ガスの通路とした回転ドラム型有機溶剤処理装置に導入し、前記有機溶剤回収装置から排出される微少な有機溶剤をバックアップ処理すると共に、前記回転ドラム型有機溶剤処理装置の脱着処理ガスを前記有機溶剤回収装置に戻すよう構成されるシステムが提案されている。
【０００８】
しかしながら、前記システムは以下に示すような不具合がある。
（１）前段の有機溶剤回収装置がスチーム脱着であるため、脱着スチームの凝縮水が吸着材（活性炭素繊維又は粒状活性炭）残留するため、脱着処理から切り換わり後の吸着処理においてスチーム凝縮水のミストが飛散しバックアップ装置の吸着性能を低下させる。また、ミストによる性能低下を防ぐためには、有機溶剤回収装置とバックアップ処理装置との間に水蒸気を冷却・除去できる冷却機構（例えばコンデンサー）を設ける必要があり、余分な設備コスト、ランニングコストかかる。
【０００９】
（２）前段の有機溶剤回収装置がスチーム脱着であるため、有機溶剤回収装置から多量のスチームドレン水が回収されるので回収溶剤を再利用する場合の分離コストが非常に大きい。また、回収液を産業廃棄物として処理する場合でも処理コストが嵩む。
【００１０】
（３）前段の有機溶剤回収装置がバッチ処理のため、吸着と脱着が切り替わる際に圧力変動が生じ、一次側（被処理ガス側）の圧力変動が許容されない工程の処理には適用できない。また、バックアップ処理装置の吸着工程に圧力変動が生じるのでバックアップ処理装置が吸着材を担持したハニカム構造の管状孔を有機溶剤含有ガスの通路とした回転ドラム型有機溶剤処理装置の場合には吸着と脱着の圧力バランス変動が前記バックアップ処理装置の性能低下を引き起こす原因となる。
【００１１】
【特許文献１】
特開２００１−１７９０４１
【特許文献２】
特開平９−３０８８１４
【００１２】
【発明が解決しようとする課題】
有機溶剤回収装置で処理した処理ガス中からリークした有機溶剤をバックアップ処理装置によって環境に対して安全に対処する有機溶剤回収システム及び有機溶剤回収方法において、有機溶剤回収装置がスチーム脱着であってバッチ式の場合は、有機溶剤回収装置の排ガス中の有機溶剤濃度が不安定になり易い。本発明は、このような事情に鑑みてなされたものであって、環境への有機溶剤の拡散を安定的に低減することができる、有機溶剤含有ガスから有機溶剤を回収する効率の良い有機溶剤回収システム及びその方法を提供することを目的とする。
【００１３】
【課題を解決するための手段】
即ち本発明は、下記Ａ及びＢを有する事を特徴とする有機溶剤回収システムである。
Ａ：固体吸着剤粒子を有機溶剤含有ガス吸着部に連続的に供給し、該部で溶剤成分を吸着した吸着剤粒子を該装置の吸着剤再生部に送り、これを再生し、再生された吸着剤粒子を再び有機溶剤含有ガス吸着部に供給して連続的にガスを浄化すると共に、吸着剤の再生部で脱着した有機溶剤を液化回収するための凝縮部を備えた有機溶剤回収装置。
Ｂ：前記有機溶剤回収装置で吸着処理された処理済ガス中にリークした有機溶剤を連続又はバッチで吸着・脱着処理を行うことができ、該脱着処理された有機溶剤含有ガスが前記有機溶剤回収装置の吸着部に戻されるように構成されるバックアップ処理装置。
また本発明は、有機溶剤回収装置が多段流動層吸着装置であることを特徴とする有機溶剤回収システムである。また本発明は、バックアップ処理装置が、円柱状又は円筒状に形成されたハニカム状吸着体が吸着領域、再生領域を巡回し連続的に有機溶剤の吸・脱着処理を行うよう構成されている連続式吸・脱着装置であることを特徴とする有機溶剤回収システムである。また本発明は、バックアップ処理装置が、吸着とスチームによる脱着をバッチ処理で交互に行う２槽以上の吸着槽と脱着された有機溶剤を液化回収するための凝縮器）を備える有機溶剤回収装置であることを特徴とする有機溶剤回収システムである。また本発明は、吸着とスチームによる脱着を交互に切り換えて行うバッチ式バックアップ処理装置のコンデンサーの出口ガスラインを前記有機溶剤回収装置の有機溶剤含有ガスラインに合流させ、前記バックアップ処理装置のコンデンサーからの未凝縮ガスを前記有機溶剤回収装置にて吸着処理する有機溶剤回収システムである。またさらに本発明は、前記有機溶剤回収装置とバックアップ処理装置との間に、ガスクーラーを設け該有機溶剤回収装置からの処理済みガスの冷却を行うことを特徴とする有機溶剤回収システムである。
つまり、上記目的を達成し得た本発明の処理システム及び処理方法とは、固体吸着剤粒子を有機溶剤含有ガス吸着部に連続的に供給し、該部で溶剤成分を吸着した吸着剤粒子を該装置の吸着剤再生部に送り、これを再生し、再生された吸着剤粒子を再び有機溶剤含有ガス吸着部に供給して連続的にガスを浄化すると共に、吸着剤の再生部で脱着した有機溶剤を液化回収するための凝縮部を備えた有機溶剤回収装置と、前記有機溶剤回収装置で吸着処理された処理済ガス中にリークした有機溶剤を連続又はバッチで吸着・脱着処理を行うことができ、該脱着処理された有機溶剤含有ガスが前記有機溶剤回収装置の吸着部に戻されるように構成されるバックアップ処理装置とを有する点に要旨を有するものである。
【００１４】
【発明の実施の形態】
図１及び図２は本発明の好ましい実施の一形態の例を示す有機溶剤回収システムフロー図である。本発明の有機溶剤回収システムは、大きく分けて有機溶剤含有ガスを導入することができ、有機溶剤を吸着処理し、脱着・回収処理することができる有機溶剤回収装置と、該有機溶剤回収装置から排出される吸着処理済ガスを受け入れ、該処理済ガス中にリークしている有機溶剤の吸着処理及び脱着処理ができ、且つ前記有機溶剤回収装置へ搬送することができるバックアップ処理装置とから構成される。
【００１５】
図１において、工場、作業場からの排出ガス等の有機溶剤含有ガスは、送風機１により被処理ガス導入ライン２を搬送されて吸着塔３へ導入される。吸着塔３の上部に接続された吸着剤導入ライン４から吸着剤搬送ブロワ５の気流によって固体吸着剤粒子（例えば球形活性炭粒子）６が吸着塔３に導入される。
【００１６】
吸着塔３の内部は複数の多孔板７からなる皿形段によって仕切られており、前記固体吸着剤粒子は多孔板７の持つ勾配に沿って流動層を形成しながら重力移動を行う。固体吸着材粒子の移動が上下向かい合う段で左右反対向きになるように段の勾配も上下の段で逆向きになっている。
【００１７】
被処理ガス導入ライン２から導入された有機溶剤含有ガスは吸着塔３内を鉛直上向する気流となり、多孔板７からなる皿形段に沿って流動降下する固体吸着剤粒子６と向流接触することによって有機物が吸着除去される。
【００１８】
有機溶剤含有ガスと接触し有機溶剤を吸着した固体吸着剤粒子６は、吸着塔３の下部に接続された吸着剤排出ライン８を通って、前記吸着剤搬送ブロワ５の気流によって吸着剤搬送ライン９、脱着部導入ライン１０を経て脱着部１１に導入される。
【００１９】
脱着部１１は電気ヒーター１２によって外部から加熱され、脱着部を固体吸着剤粒子が重力降下する間に吸着した有機溶剤を脱着できる温度まで加熱される。尚、前記ヒーターは固体吸着剤を効率よく加熱するのが目的であり、加熱方法は電気に限らず、オイルやスチームを熱媒とするヒーターであってもよい。
【００２０】
前記脱着部の下方には脱着用ガス導入ライン１３が接続されており、例えば窒素ガスを該脱着用ガス導入ライン１３に導入し、脱着部で有機溶剤が脱着可能な温度まで加熱された固体吸着剤粒子６と接触し、固体吸着剤から有機溶剤を脱離する。前記脱着操作によって、有機溶剤を含む窒素ガスは脱着ガス排出ライン１４を経てコンデンサー１５に導入される。コンデンサーで冷却され凝縮した有機溶剤は有機溶剤回収タンク１６で溜められ、溜まった溶剤はオーバーフローにて排出される。一方、未凝縮の有機溶剤を含む窒素ガスは未凝縮ガス排出ライン１７を経て脱着部１１の固体吸着剤導入部に導入され、ここで未凝縮の溶剤分が吸着される。尚、吸着処理する溶剤が不燃性である場合には脱着用ガスは空気でも良い。
【００２１】
脱着部で脱着処理された固体吸着剤は、脱着部の底部から前記吸着材搬送ブロワ５によって吸着塔３の上部に接続された吸着材導入ライン４を経て吸着塔に導入され、再び有機溶剤を吸着する。以上説明したように固体吸着剤は、吸着部と脱着部を重力降下及び搬送ガスによって循環している。
【００２２】
前記有機溶剤回収装置から排出される処理済ガスは、処理済ガス導入ライン１８を通じて、円柱状又は円筒状に形成されたハニカム状吸着体が吸着領域、再生領域を巡回し連続的に有機溶剤の吸・脱着処理を行うことのできるバックアップ処理装置１９に導入され、該処理済ガス中にリークしている有機溶剤は吸着され、同時に該バックアップ処理装置１９で処理されたガスは清浄ガスとして排出される。
【００２３】
さらに、バックアップ処理装置１９は、濃縮された有機溶剤含有脱着ガスを溶剤回収装置の吸着塔３に戻す機能を有する（図１のア）。このシステムによって装置からの有機排出濃度を低減できるばかりでなく、有機溶剤回収装置、バックアップ処理装置とも脱着にスチームを用いないので、回収溶剤中の水分を最小限に抑えることができ、回収有機溶剤と共に回収される廃水処理費が非常に少なく、コストパフォーマンスの高いシステムである。
【００２４】
前記有機溶剤回収システムはバックアップ処理のコストパフォーマンスを考えると被処理ガスの風量が中〜大風量（数百〜数千ｍ³／ｍｉｎ）の場合に好適であるが、一方、被処理ガスの風量が小風量（数十ｍ³／ｍｉｎ程度）で高濃度（数万ｐｐｍ以上）の場合にはバックアップ処理装置はバッチ式の溶剤回収装置の方が有利となる場合が多い。また、バックアップ処理装置で発生する脱着スチームのドレン水の量も小風量の場合は装置が小型になるので少なくて済む。
【００２５】
図２に、バックアップ処理装置として、吸着材２２を充填した吸着槽２３を備え処理ガス導入ダンパー２４、２５及び処理ガス排出ダンパー２６、２７の交互切り換えによって吸着とスチームによる脱着をバッチ処理で行い、脱着された有機溶剤を液化回収するための凝縮器（コンデンサー）を備える有機溶剤回収装置を用いた場合のシステムフロー図を示す。
【００２６】
前記バッチ式バックアップ処理装置は、該バックアップ処理装置が脱着処理工程に切り換わる度毎に脱着スチームによって吸着槽内のデッドボリューム分の空気が押し出され、その空気がコンデンサーを経由することによって発生する、コンデンサー内の飽和溶剤分を含む高濃度の溶剤ガスを、前記有機溶剤回収装置の吸着塔３に戻す機能を有する（図２のイ）。
【００２７】
図１、図２において、有機溶剤回収装置とバックアップ処理装置との間に有機溶剤回収装置から排出される処理済ガスを冷却するためのガスクーラーを設けても良い。前記有機溶剤回収装置は脱着にスチームを用いないので、処理済ガスと同伴するミスト分は無く、また、有機溶剤回収装置によって被処理ガス中の水分が吸着されているので、処理済ガス中の絶対湿度は非常に低く、ガスクーラーで冷却してもドレン水は生じず、ドレンの排出は不要である。
【００２８】
有機溶剤回収装置に用いられる固体吸着剤粒子は球形のものが好ましく、素材は有機溶剤を吸着できるものであって、活性炭、ゼオライト、シリカゲル等が好ましい。また、バックアップ処理装置に用いられる吸着剤は、連続回転式のハニカム状吸着体であれば活性炭、ゼオライト、シリカゲルが好ましく、バッチ式であれば活性炭素繊維、粒状活性炭が好ましい。
【００２９】
［実施例１］
図１に示される有機溶剤回収システムにおいて、以下に示す条件で被処理ガスを清浄化処理し、有機溶剤を回収した。
【００３０】
除去成分として、メチルエチルケトン（ＭＥＫ）１０００ｐｐｍを含む温度２５℃、相対湿度５０％、被処理ガス風量５０Ｎｍ³／ｍｉｎで有機溶剤回収装置の吸着塔に供給した。また、吸着塔の塔径は１１００ｍｍφとし、吸着部は１２段の多段トレイを有する多段流動床式の構成とした。これらの吸着部に、吸着剤として石油ピッチ系球状活性炭を流動させた。球状活性炭の循環流量は４００ｋｇ／ｈとした。
【００３１】
また、脱着部の塔径を８００ｍｍφとし、熱交換部には熱媒としてスチームを供給し間接加熱を行った。この時の脱着温度は１４０℃であり、キャリアガスとして窒素ガスを８６ｍ³／ｈの体積流量で循環させた。さらに、凝縮部には冷媒として７℃のチラー水を流し、脱着された被除去成分を冷却して液化させた。その結果、吸着塔の出口における処理済ガスのＭＥＫ濃度は５０ｐｐｍであった。
【００３２】
この処理済ガスを継続的にバックアップ処理装置に導入した。バックアップ処理装置は、粒状活性炭を担持した直径７７０ｍｍ、厚み４５０ｍｍのディスク型有機溶剤吸着濃縮装置を使用し、脱着処理は濃縮倍率が３倍となるように加熱空気量をコントロールした。バックアップ処理装置において脱着したＭＥＫ含有ガスを吸着塔に戻した。本実施例１のシステムにより清浄化されたガス（バックアップ処理装置での処理後のガス）中のＭＥＫ濃度は、１．８〜２．２ｐｐｍ（平均２．０ｐｐｍ）までに低減された。
【００３３】
［実施例２］
図２に示される有機溶剤回収システムにおいて、以下に示す条件で被処理ガスを清浄化処理し、有機溶剤を回収した。
【００３４】
除去成分として塩化ビニルモノマー（ＶＣＭ）１００００ｐｐｍを含む温度２５℃、相対湿度５０％、被処理ガス風量５０Ｎｍ³／ｍｉｎで有機溶剤回収装置の吸着塔に供給した。また、吸着塔の塔径は１１００ｍｍφとし、吸着部は１６段の多段トレイを有する多段流動床式の構成とした。これらの吸着部に、吸着剤として石油ピッチ系球状活性炭を流動させた。球状活性炭の循環流量は５４０ｋｇ／ｈとした。
【００３５】
また、脱着部の塔径を８００ｍｍφとし、熱交換部には熱媒としてスチームを供給し間接加熱を行った。この時の脱着温度は１４０℃であり、キャリアガスとして窒素ガスを６０ｍ³／ｈの体積流量で循環させた。さらに、凝縮部には冷媒として７℃のチラー水を流し、脱着された水分を凝縮除去して、高濃度のＶＣＭガスを得た。高濃度のＶＣＭガスは工程に戻して再利用した。吸着塔の出口における処理済ガスのＶＣＭ濃度は４８０ｐｐｍであった。
【００３６】
この処理済ガスを継続的にバックアップ処理装置に導入した。バックアップ処理装置は、一塔につき２０ｋｇの活性炭素繊維を充填した吸着塔を２塔使用し、吸着時間８分間、スチームによる脱着時間６分間の交互切り換え方式で、ＶＣＭの吸着と脱着を行った。脱着により得られたＶＣＭとスチームの混合ガスはコンデンサーに導入し、スチームを凝縮させ、未凝縮のＶＣＭガスは多段流動層吸着装置の吸着塔に戻した。本実施例２のシステムにより清浄化されたガス（バックアップ処理装置での処理後のガス）中のＶＣＭ濃度は、平均９．６ｐｐｍまでに低減された。
【００３７】
【発明の効果】
以上説明したように、本発明の有機溶剤回収システム及び有機溶剤回収方法は、環境への有機溶剤の拡散を安定的に低減することができ、有機溶剤含有ガスから有機溶剤を効率良く回収し、回収液の処理コストも安くできる。
【図面の簡単な説明】
【図１】本発明の好ましい実施の一形態の例である、バックアップ処理装置としてディスク型有機溶剤吸着濃縮装置を用いた場合の有機溶剤回収システムフロー図である。
【図２】本発明の好ましい実施の一形態の例である、バックアップ処理装置としてスチーム脱着のバッチ切り換え式の有機溶剤回収装置を用いた場合の有機溶剤処理システムフロー図である。
【符号の説明】
１送風機
２被処理ガス導入ライン
３吸着塔
４吸着剤導入ライン
５吸着材搬送ブロワ
６固体吸着材
７多孔板
８吸着剤排出ライン
９吸着剤搬送ライン
１０脱着部導入ライン
１１脱着部
１２電気ヒーター
１３脱着用ガス導入ライン
１４脱着ガス排出ライン
１５コンデンサー
１６有機溶剤回収タンク
１７未凝縮ガス排出ライン
１８処理済ガス導入ライン
１９バックアップ処理装置
２０ハニカム状吸着体
２１ヒーター
２２吸着材
２３吸着槽
２４、２５処理ガス導入ダンパー
２６、２７処理ガス排出ダンパー
２８スチーム導入ライン
２９回収ガスライン
３０コンデンサー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating an organic solvent-containing gas, and more particularly, to a treatment system and method for reducing the concentration of an organic solvent in exhaust gas.
[0002]
[Prior art]
In recent years, emission concentration regulations for harmful air pollutants have been strengthened, and it is desired to reduce the concentration of exhaust gas from organic solvent-containing gas treatment devices.
[0003]
Conventionally, as the above gas treatment apparatus, for example, a pair of adsorption tanks that adsorb an organic solvent in an organic solvent-containing gas (treated gas) with activated carbon fiber material, treated gas supply means and desorption gas for each adsorption tank There is provided a supply means, and switching means for switching between an adsorption treatment state in which the gas to be treated is supplied to the adsorption adsorption tank and a desorption treatment state in which the desorption gas is supplied. In order to reduce the concentration and improve the recovery efficiency of the organic solvent, in Patent Document 1, three or more adsorption tanks are provided, and a plurality of adsorption tanks among the three or more adsorption tanks are connected in series and adsorbed. It is configured so that at least one adsorption tank of the three or more adsorption tanks is in a desorption process state, and at least one adsorption tank in the desorption process state is in a desorption process state. Cut off Before it is replaced, configured and Equipments has been proposed as a suction tank located on the upstream side of the plurality of series adsorption state. That is, an adsorption tank having a small amount of organic solvent components after the desorption treatment is disposed on the lower side of a plurality of serial adsorption tanks, and is used as a backup so that the concentration of the organic solvent in the exhaust gas is stably kept low.
[0004]
However, since the desorption process in the case of recovering the organic solvent in the apparatus is usually performed by steam, the adsorbent in the lower side adsorption tank as a backup is in a high temperature and wet state after switching to the adsorption process step, At the initial stage of adsorption, a minute residual component of the organic solvent in the adsorbent is pushed out by the adsorbed gas, or the adsorption efficiency is easily lowered or the adsorbed gas is easily removed due to the wetness of the adsorbent.
[0005]
In particular, when performing a backup process by serial adsorption, the concentration of the gas to be treated is usually a high concentration of several thousand to several tens of thousands ppm, and since it is two-time adsorption in series, The amount of adsorption is large compared to the case of low concentration, one-stage adsorption treatment, and the exhaust concentration rise due to the extrusion becomes remarkable.
[0006]
In addition, in the case of a solvent with a low boiling point and a low adsorptivity to the activated carbon material or a water-soluble solvent, the degree of adsorption efficiency is greatly reduced due to the wetness of the adsorbent, and the degree of omission is large. Even in the case of exhaust gas, the degree to which the exhaust concentration becomes high at the initial stage of adsorption immediately after switching from the desorption process is large, and the requirement cannot be satisfied if the exhaust concentration standard is very strict.
[0007]
Furthermore, in Patent Document 2, in a solvent recovery apparatus that performs adsorption of gas to be processed and desorption by steam in a batch process for the purpose of reducing the diffusion of the organic solvent to the environment as much as possible, the process discharged from the organic solvent recovery apparatus The spent gas is introduced into a rotating drum type organic solvent processing device using a tubular hole in the honeycomb structure carrying an adsorbent as a passage for the organic solvent-containing gas, and a small amount of organic solvent discharged from the organic solvent recovery device is backed up. In addition, there has been proposed a system configured to return the desorption processing gas of the rotating drum type organic solvent processing apparatus to the organic solvent recovery apparatus.
[0008]
However, the system has the following problems.
(1) Since the organic solvent recovery device in the previous stage is steam desorption, the condensed water of the desorbed steam remains in the adsorbent (activated carbon fiber or granular activated carbon), so that the steam condensed water in the adsorption process after switching from the desorption process Mist is scattered and the adsorption performance of the backup device is reduced. In addition, in order to prevent performance degradation due to mist, it is necessary to provide a cooling mechanism (for example, a condenser) that can cool and remove water vapor between the organic solvent recovery device and the backup processing device, which requires extra equipment cost and running cost.
[0009]
(2) Since the upstream organic solvent recovery device is steam desorption, a large amount of steam drain water is recovered from the organic solvent recovery device, so that the separation cost for reusing the recovered solvent is very high. Further, even when the recovered liquid is processed as industrial waste, the processing cost increases.
[0010]
(3) Since the organic solvent recovery apparatus in the previous stage is a batch process, pressure fluctuation occurs when the adsorption and desorption are switched, and the process cannot be applied to a process in which the pressure fluctuation on the primary side (the gas to be treated) is not allowed. In addition, since pressure fluctuation occurs in the adsorption process of the backup processing apparatus, the backup processing apparatus uses adsorption in the case of a rotating drum type organic solvent processing apparatus in which a tubular hole of a honeycomb structure carrying an adsorbent is used as a path for organic solvent-containing gas. Variations in the pressure balance of desorption cause a decrease in the performance of the backup processing apparatus.
[0011]
[Patent Document 1]
JP2001-179041A
[Patent Document 2]
JP-A-9-308814
[0012]
[Problems to be solved by the invention]
In an organic solvent recovery system and an organic solvent recovery method in which an organic solvent leaked from a processing gas processed by an organic solvent recovery device is safely handled with respect to the environment by a backup processing device. In the case of the formula, the concentration of the organic solvent in the exhaust gas of the organic solvent recovery device tends to be unstable. The present invention has been made in view of such circumstances, and can efficiently reduce the diffusion of the organic solvent to the environment, and is an efficient organic solvent for recovering the organic solvent from the organic solvent-containing gas. It is an object of the present invention to provide a recovery system and method.
[0013]
[Means for Solving the Problems]
That is, the present invention is an organic solvent recovery system having the following A and B.
A: The solid adsorbent particles were continuously supplied to the organic solvent-containing gas adsorbing section, and adsorbent particles having adsorbed the solvent component in the section were sent to the adsorbent regeneration section of the apparatus, which was regenerated and regenerated. An organic solvent recovery device comprising a condensing unit for liquefying and recovering the organic solvent desorbed by the adsorbent regeneration unit while continuously purifying the gas by supplying the adsorbent particles again to the organic solvent-containing gas adsorption unit.
B: The organic solvent leaked in the treated gas adsorbed by the organic solvent recovery device can be adsorbed / desorbed continuously or batchwise, and the desorbed organic solvent-containing gas is recovered by the organic solvent. A backup processing device configured to be returned to the suction unit of the device.
The present invention is also the organic solvent recovery system, wherein the organic solvent recovery device is a multistage fluidized bed adsorption device. Further, in the present invention, the backup processing apparatus is configured such that a honeycomb-shaped adsorbent formed in a columnar shape or a cylindrical shape circulates the adsorption region and the regeneration region and continuously performs the organic solvent absorption / desorption processing. It is an organic solvent recovery system characterized by being a type adsorption / desorption device. Further, the present invention is an organic solvent recovery apparatus in which the backup processing apparatus includes two or more adsorption tanks that alternately perform adsorption and desorption by steam and a condenser for liquefying and recovering the desorbed organic solvent. It is an organic solvent recovery system characterized by being. The present invention also combines the outlet gas line of the condenser of the batch type backup processing apparatus that alternately switches between adsorption and desorption by steam to the organic solvent-containing gas line of the organic solvent recovery apparatus, from the condenser of the backup processing apparatus. It is an organic solvent collection | recovery system which carries out the adsorption process of the non-condensable gas of the said organic solvent collection | recovery apparatus. Furthermore, the present invention is an organic solvent recovery system in which a gas cooler is provided between the organic solvent recovery device and the backup processing device to cool the processed gas from the organic solvent recovery device.
In other words, the processing system and the processing method of the present invention that can achieve the above-mentioned object are that the solid adsorbent particles are continuously supplied to the organic solvent-containing gas adsorbing portion, and the adsorbent particles having adsorbed the solvent component in the portion are provided. It is sent to the adsorbent regeneration section of the apparatus, regenerated, and the regenerated adsorbent particles are again supplied to the organic solvent-containing gas adsorption section to continuously purify the gas and desorbed at the adsorbent regeneration section. An organic solvent recovery device having a condensing unit for liquefying and recovering the organic solvent, and an organic solvent leaking into the treated gas adsorbed by the organic solvent recovery device is subjected to adsorption / desorption processing continuously or batchwise. And a backup processing device configured to return the desorbed organic solvent-containing gas to the adsorption portion of the organic solvent recovery device.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 are organic solvent recovery system flow charts showing an example of a preferred embodiment of the present invention. The organic solvent recovery system of the present invention can be broadly divided into an organic solvent-containing gas, an organic solvent recovery device capable of adsorbing, desorbing and recovering an organic solvent, and the organic solvent recovery device. It is composed of a backup processing device that accepts the exhausted gas that has been discharged, can adsorb and desorb the organic solvent leaking into the processed gas, and can be transported to the organic solvent recovery device. The
[0015]
In FIG. 1, an organic solvent-containing gas such as exhaust gas from a factory or work place is conveyed by a blower 1 through a gas introduction line 2 to be introduced into an adsorption tower 3. Solid adsorbent particles (for example, spherical activated carbon particles) 6 are introduced into the adsorption tower 3 from the adsorbent introduction line 4 connected to the upper part of the adsorption tower 3 by the air current of the adsorbent transport blower 5.
[0016]
The inside of the adsorption tower 3 is partitioned by a plate-shaped step composed of a plurality of perforated plates 7, and the solid adsorbent particles move by gravity while forming a fluidized bed along the gradient of the perforated plate 7. The gradient of the steps is also reversed in the upper and lower steps so that the movement of the solid adsorbent particles is in the opposite direction in the steps facing each other.
[0017]
The organic solvent-containing gas introduced from the gas to be treated introduction line 2 becomes an air flow vertically upward in the adsorption tower 3, and is in countercurrent contact with the solid adsorbent particles 6 that flow down along the dish-shaped stage composed of the perforated plate 7. By doing so, the organic matter is adsorbed and removed.
[0018]
The solid adsorbent particles 6 that have come into contact with the organic solvent-containing gas and adsorbed the organic solvent pass through the adsorbent discharge line 8 connected to the lower part of the adsorption tower 3, and the adsorbent transport line is generated by the air flow of the adsorbent transport blower 5. 9, it is introduced into the desorption part 11 through the desorption part introduction line 10.
[0019]
The desorption unit 11 is heated from the outside by an electric heater 12, and the desorption unit is heated to a temperature at which the adsorbed organic solvent can be desorbed while the solid adsorbent particles are gravity lowered. The heater is intended to efficiently heat the solid adsorbent, and the heating method is not limited to electricity, and may be a heater using oil or steam as a heat medium.
[0020]
A desorption gas introduction line 13 is connected to the lower part of the desorption part. For example, nitrogen gas is introduced into the desorption gas introduction line 13 and heated to a temperature at which the organic solvent can be desorbed in the desorption part. The organic solvent is desorbed from the solid adsorbent by contacting with the agent particles 6. By the desorption operation, nitrogen gas containing an organic solvent is introduced into the condenser 15 through the desorption gas discharge line 14. The organic solvent cooled and condensed by the condenser is stored in the organic solvent recovery tank 16, and the stored solvent is discharged by overflow. On the other hand, the nitrogen gas containing the non-condensed organic solvent is introduced into the solid adsorbent introduction part of the desorption part 11 through the non-condensable gas discharge line 17, where the non-condensed solvent is adsorbed. When the solvent to be adsorbed is nonflammable, the desorption gas may be air.
[0021]
The solid adsorbent desorbed in the desorption part is introduced into the adsorption tower from the bottom of the desorption part through the adsorbent introduction line 4 connected to the upper part of the adsorption tower 3 by the adsorbent transport blower 5, and again the organic solvent is removed. Adsorb. As described above, the solid adsorbent circulates between the adsorbing part and the desorbing part by gravity drop and carrier gas.
[0022]
The treated gas discharged from the organic solvent recovery device passes through the treated gas introduction line 18 and the honeycomb-shaped adsorbent formed in a columnar shape or a cylindrical shape circulates in the adsorption region and the regeneration region, and continuously contains the organic solvent. The organic solvent leaking into the treated gas introduced into the backup processing device 19 capable of performing the adsorption / desorption treatment is adsorbed, and at the same time, the gas treated by the backup processing device 19 is discharged as a clean gas. The
[0023]
Further, the backup processing device 19 has a function of returning the concentrated organic solvent-containing desorption gas to the adsorption tower 3 of the solvent recovery device (a in FIG. 1). This system not only reduces the organic emission concentration from the equipment, but also does not use steam for desorption in both the organic solvent recovery equipment and the backup processing equipment, so that the water content in the recovered solvent can be kept to a minimum. The cost of wastewater treatment collected with the system is very low and the system has high cost performance.
[0024]
The organic solvent recovery system is suitable when the gas flow rate of the gas to be treated is medium to large (a few hundred to several thousand m ³ / min) in consideration of the cost performance of the backup process. Is a small amount of air (about several tens of m ³ / min) and a high concentration (tens of thousands of ppm or more), the batch processing solvent recovery device is often more advantageous for the backup processing device. In addition, when the amount of drain water of the desorption steam generated in the backup processing device is small, the device is small, and therefore the amount can be reduced.
[0025]
In FIG. 2, as a backup processing apparatus, an adsorption tank 23 filled with an adsorbent 22 is provided, and adsorption and desorption by steam are performed in a batch process by alternately switching process gas introduction dampers 24 and 25 and process gas discharge dampers 26 and 27. The system flow figure at the time of using the organic-solvent collection | recovery apparatus provided with the condenser (condenser) for liquefying and collect | recovering the desorbed organic solvents is shown.
[0026]
The batch-type backup processing device is generated when the air for the dead volume in the adsorption tank is pushed out by the desorption steam every time the backup processing device is switched to the desorption processing step, and the air passes through the condenser. It has a function of returning a high-concentration solvent gas containing a saturated solvent content in the condenser to the adsorption tower 3 of the organic solvent recovery device (a in FIG. 2).
[0027]
1 and 2, a gas cooler for cooling the processed gas discharged from the organic solvent recovery device may be provided between the organic solvent recovery device and the backup processing device. Since the organic solvent recovery device does not use steam for desorption, there is no mist accompanying the processed gas, and moisture in the gas to be processed is adsorbed by the organic solvent recovery device. The absolute humidity is very low, and even when cooled by a gas cooler, no drain water is produced and drainage is not required.
[0028]
The solid adsorbent particles used in the organic solvent recovery device are preferably spherical, and the material can adsorb the organic solvent, and activated carbon, zeolite, silica gel and the like are preferable. Further, the adsorbent used in the backup processing apparatus is preferably activated carbon, zeolite, or silica gel if it is a continuously rotating honeycomb adsorbent, and activated carbon fiber or granular activated carbon is preferable if it is a batch type.
[0029]
[Example 1]
In the organic solvent recovery system shown in FIG. 1, the gas to be processed was cleaned under the following conditions to recover the organic solvent.
[0030]
As a removal component, it was supplied to the adsorption tower of the organic solvent recovery apparatus at a temperature of 25 ° C. containing 1000 ppm of methyl ethyl ketone (MEK), a relative humidity of 50%, and a gas flow to be treated of 50 Nm ³ / min. Moreover, the tower diameter of the adsorption tower was 1100 mmφ, and the adsorption part had a multistage fluidized bed configuration having 12 multistage trays. In these adsorbing portions, petroleum pitch-based spherical activated carbon was flowed as an adsorbent. The circulation flow rate of the spherical activated carbon was 400 kg / h.
[0031]
Moreover, the tower diameter of the desorption part was set to 800 mmφ, and steam was supplied to the heat exchange part as a heat medium for indirect heating. The desorption temperature at this time was 140 ° C., and nitrogen gas was circulated as a carrier gas at a volume flow rate of 86 m ³ / h. Further, chiller water at 7 ° C. was passed as a refrigerant in the condensing part, and the desorbed component to be removed was cooled and liquefied. As a result, the MEK concentration of the treated gas at the outlet of the adsorption tower was 50 ppm.
[0032]
This treated gas was continuously introduced into the backup processing apparatus. As the backup processing apparatus, a disk type organic solvent adsorption concentrating apparatus having a diameter of 770 mm and a thickness of 450 mm carrying granular activated carbon was used. In the desorption process, the amount of heated air was controlled so that the concentration ratio was 3 times. The MEK-containing gas desorbed in the backup processing apparatus was returned to the adsorption tower. The MEK concentration in the gas cleaned by the system of Example 1 (the gas after the treatment in the backup processing apparatus) was reduced to 1.8 to 2.2 ppm (average 2.0 ppm).
[0033]
[Example 2]
In the organic solvent recovery system shown in FIG. 2, the gas to be processed was cleaned under the following conditions to recover the organic solvent.
[0034]
It was supplied to the adsorption tower of the organic solvent recovery apparatus at a temperature of 25 ° C. containing 10000 ppm of vinyl chloride monomer (VCM) as a removal component, a relative humidity of 50%, and a gas flow to be treated of 50 Nm ³ / min. The tower diameter of the adsorption tower was 1100 mmφ, and the adsorption section was of a multistage fluidized bed type having 16 multistage trays. In these adsorbing portions, petroleum pitch-based spherical activated carbon was flowed as an adsorbent. The circulation flow rate of the spherical activated carbon was 540 kg / h.
[0035]
Moreover, the tower diameter of the desorption part was set to 800 mmφ, and steam was supplied to the heat exchange part as a heat medium for indirect heating. The desorption temperature at this time was 140 ° C., and nitrogen gas was circulated as a carrier gas at a volume flow rate of 60 m ³ / h. Further, chiller water at 7 ° C. was flowed as a refrigerant through the condensing part, and the desorbed water was condensed and removed to obtain a high concentration VCM gas. The high concentration VCM gas was recycled to the process. The VCM concentration of the treated gas at the outlet of the adsorption tower was 480 ppm.
[0036]
This treated gas was continuously introduced into the backup processing apparatus. The backup treatment apparatus used two adsorption towers filled with 20 kg of activated carbon fibers per tower, and adsorbed and desorbed VCM by an alternating switching system with an adsorption time of 8 minutes and a steam desorption time of 6 minutes. The mixed gas of VCM and steam obtained by desorption was introduced into a condenser to condense the steam, and the uncondensed VCM gas was returned to the adsorption tower of the multistage fluidized bed adsorption apparatus. The VCM concentration in the gas cleaned by the system of Example 2 (the gas after the treatment in the backup processing apparatus) was reduced to an average of 9.6 ppm.
[0037]
【The invention's effect】
As described above, the organic solvent recovery system and the organic solvent recovery method of the present invention can stably reduce the diffusion of the organic solvent to the environment, efficiently recover the organic solvent from the organic solvent-containing gas, The processing cost of the recovered liquid can also be reduced.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a flow chart of an organic solvent recovery system when a disk type organic solvent adsorption concentrator is used as a backup processing apparatus as an example of a preferred embodiment of the present invention.
FIG. 2 is a flow chart of an organic solvent processing system in the case of using a batch switching type organic solvent recovery device for steam desorption as an example of a preferred embodiment of the present invention as a backup processing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Blower 2 Processed gas introduction line 3 Adsorption tower 4 Adsorbent introduction line 5 Adsorbent conveyance blower 6 Solid adsorbent 7 Porous plate 8 Adsorbent discharge line 9 Adsorbent conveyance line 10 Desorption part introduction line 11 Desorption part 12 Electric heater 13 Desorption gas introduction line 14 Desorption gas discharge line 15 Condenser 16 Organic solvent recovery tank 17 Uncondensed gas discharge line 18 Treated gas introduction line 19 Backup processing device 20 Honeycomb-shaped adsorbent 21 Heater 22 Adsorbent 23 Adsorption tanks 24 and 25 Gas introduction dampers 26, 27 Process gas discharge damper 28 Steam introduction line 29 Recovery gas line 30 Condenser

Claims

下記Ａ及びＢを有する事を特徴とする有機溶剤回収システム。
Ａ：固体吸着剤粒子を有機溶剤含有ガス吸着部に連続的に供給し、該部で溶剤成分を吸着した吸着剤粒子を該装置の吸着剤再生部に送り、これを外部から間接的に加熱される脱着部にて再生し、再生された吸着剤粒子を再び有機溶剤含有ガス吸着部に供給して連続的にガスを浄化すると共に、吸着剤の再生部で脱着した有機溶剤を液化回収するための凝縮部を備えた有機溶剤回収装置。
Ｂ：前記有機溶剤回収装置で吸着処理された処理済ガス中にリークした有機溶剤を連続で吸着・脱着処理を行うことができ、該脱着処理された有機溶剤含有ガスが前記有機溶剤回収装置の吸着部に戻されるように構成されるバックアップ処理装置であって、円柱状又は円筒状に形成されたハニカム状吸着体が吸着領域、再生領域を巡回し連続的に有機溶剤の吸・脱着処理を行うよう構成されている連続式吸・脱着装置であるバックアップ処理装置。An organic solvent recovery system characterized by having the following A and B.
A: Solid adsorbent particles are continuously supplied to the organic solvent-containing gas adsorbing section, adsorbent particles having adsorbed solvent components in the section are sent to the adsorbent regeneration section of the apparatus, and this is indirectly heated from the outside. The desorbed part is regenerated, and the regenerated adsorbent particles are supplied again to the organic solvent-containing gas adsorbing part to continuously purify the gas, and the organic solvent desorbed in the adsorbent regenerating part is liquefied and recovered. Organic solvent recovery device equipped with a condensing part.
B: The organic solvent leaked in the treated gas adsorbed by the organic solvent recovery device can be continuously adsorbed and desorbed, and the desorbed organic solvent-containing gas is contained in the organic solvent recovery device. A back-up processing device configured to be returned to the adsorption unit, in which a honeycomb-like adsorbent formed in a columnar shape or a cylindrical shape circulates the adsorption region and the regeneration region and continuously performs the adsorption / desorption treatment of the organic solvent. A backup processing device which is a continuous suction and desorption device configured to perform.

下記Ａ及びＢを有する事を特徴とする有機溶剤回収システム。
Ａ：固体吸着剤粒子を有機溶剤含有ガス吸着部に連続的に供給し、該部で溶剤成分を吸着した吸着剤粒子を該装置の吸着剤再生部に送り、これを外部から間接的に加熱される脱着部にて再生し、再生された吸着剤粒子を再び有機溶剤含有ガス吸着部に供給して連続的にガスを浄化すると共に、吸着剤の再生部で脱着した有機溶剤を液化回収するための凝縮部を備えた有機溶剤回収装置。
Ｂ：前記有機溶剤回収装置で吸着処理された処理済ガス中にリークした有機溶剤をバッチで吸着・脱着処理を行うことができ、該脱着処理された有機溶剤含有ガスが前記有機溶剤回収装置の吸着部に戻されるように構成されるバックアップ処理装置であって、吸着とスチームによる脱着をバッチ処理で交互に行う２槽以上の吸着槽と脱着された有機溶剤を液化回収するための凝縮器を備えるバックアップ処理装置。An organic solvent recovery system characterized by having the following A and B.
A: Solid adsorbent particles are continuously supplied to the organic solvent-containing gas adsorbing section, adsorbent particles having adsorbed solvent components in the section are sent to the adsorbent regeneration section of the apparatus, and this is indirectly heated from the outside. The desorbed part is regenerated, and the regenerated adsorbent particles are supplied again to the organic solvent-containing gas adsorbing part to continuously purify the gas, and the organic solvent desorbed in the adsorbent regenerating part is liquefied and recovered. Organic solvent recovery device equipped with a condensing part.
B: The organic solvent leaked in the treated gas adsorbed by the organic solvent recovery device can be adsorbed and desorbed in batches, and the desorbed organic solvent-containing gas is contained in the organic solvent recovery device. A backup processing apparatus configured to be returned to the adsorption unit, comprising two or more adsorption tanks alternately performing adsorption and desorption by steam and a condenser for liquefying and recovering the desorbed organic solvent A backup processing apparatus.

有機溶剤回収装置が多段流動層吸着装置であることを特徴とする請求項１又は２に記載の有機溶剤回収システム。 The organic solvent recovery system according to claim 1 or 2, wherein the organic solvent recovery device is a multistage fluidized bed adsorption device.

吸着とスチームによる脱着を交互に切り換えて行うバッチ式バックアップ処理装置のコンデンサーの出口ガスラインを前記有機溶剤回収装置の有機溶剤含有ガスラインに合流させ、前記バックアップ処理装置のコンデンサーからの未凝縮ガスを前記有機溶剤回収装置にて吸着処理する請求項２又は３に記載の有機溶剤回収システム。 The outlet gas line of the condenser of the batch type backup processing apparatus that alternately performs adsorption and desorption by steam is joined to the organic solvent-containing gas line of the organic solvent recovery apparatus, and uncondensed gas from the condenser of the backup processing apparatus is removed. The organic solvent recovery system according to claim 2 or 3, wherein the organic solvent recovery device performs an adsorption treatment.

前記有機溶剤回収装置とバックアップ処理装置との間に、ガスクーラーを設け該有機溶剤回収装置からの処理済みガスの冷却を行うことを特徴とする請求項１乃至４のいずれかに記載の有機溶剤回収システム。Wherein between the organic solvent recovery apparatus and the backup processor, an organic solvent according to any one of claims 1 to 4, characterized in that for cooling the treated gas from the organic solvent recovery apparatus provided with a gas cooler Collection system.