JP2004008987A

JP2004008987A - Treatment device for inflammable volatile organic compound gas, treatment system for the same, and method of treating the same

Info

Publication number: JP2004008987A
Application number: JP2002168453A
Authority: JP
Inventors: Yoichi Nagasaki; 長崎　洋一; Toshiki Suzuki; 鈴木　俊貴; Kunimasa Muroi; 室井　國昌
Original assignee: Yamaha Corp
Current assignee: Yamaha Corp
Priority date: 2002-06-10
Filing date: 2002-06-10
Publication date: 2004-01-15

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment device for inflammable VOC gas to efficiently remove inflammable VOC gas contained in exhaust gas and decompose it, and also to provide a treatment system for the same, and further provide a treatment method for the same. <P>SOLUTION: This device is provided with a gas introducing part 1, an adsorption part 2 to adsorb the inflammable VOC gas, a substitution gas supply part 6 to supply the substitution gas, a heating part 5, and a detection part 11 to detect concentration and temperature of oxygen gas. This treatment method comprises an adsorption process for adsorbing and removing the inflammable VOC gas in the adsorption part 2, a predesorption process for maintaining the concentration of the oxygen gas of < 8% in atmosphere in the adsorption part 2 in which the inflammable VOC gas is adsorbed, a desorption process for desorbing the inflammable VOC gas through heating of the adsorption part 2, a combustion process for burning the desorbed inflammable VOC gas, and a cooling process for cooling the adsorption part 2 after combustion of the inflammable VOC gas. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、排ガス中に含まれる可燃性の揮発性有機化合物ガスを効率的に除去、分解する可燃性の揮発性有機化合物ガス処理装置、可燃性の揮発性有機化合物ガス処理システム、可燃性の揮発性有機化合物ガス処理方法に関する。
【０００２】
【従来の技術】
従来、印刷・塗装工場、化学プラント、食品加工業などでは、ベンゼン、トルエンなどの可燃性の揮発性有機化合物（Ｖｏｌａｔｉｌｅ　Ｏｒｇａｎｉｃ　Ｃｏｍｐｏｕｎｄｓ、以下、「ＶＯＣ」と略すこともある。）が広く用いられてきた。
近年、大気汚染防止法において、ＶＯＣの一部が有害大気汚染物質として、優先取得物質、自主管理物質に指定されて以来、工場などから排出される排ガス中に含まれるＶＯＣガスの排出量を排出基準以下に抑えるために、種々のＶＯＣガスの処理方法が考案されている。
【０００３】
ＶＯＣガスの処理方法としては、排出されたＶＯＣガスを燃焼炉内で直接、燃焼分解する直接燃焼法（特開平１１−８２８７９）、排出されたＶＯＣガスを触媒燃焼炉内で燃焼分解する触媒燃焼法（特開平１０−２６７９２８、特開２００１−９０９３１）、排出されたＶＯＣガスを圧縮し、凝縮液化法で回収する凝縮回収法、排出されたＶＯＣガスを活性炭に吸着させて浄化する吸着除去法（特開平７−２８９８４３）などが挙げられる。
【０００４】
【発明が解決しようとする課題】
しかし、直接燃焼法では、排ガス中のＶＯＣガスの濃度が８００ｐｐｍ未満の場合、ＶＯＣガスの燃焼における燃費が非常に悪く、実用的ではない。また、ＶＯＣガスの濃度が爆発下限より高い場合は、防爆対策が必要である。
触媒燃焼法では、排ガス中のＶＯＣガスの濃度が２００ｐｐｍ未満の場合、ＶＯＣガスの自己燃焼のみにより触媒燃焼温度を適正な温度範囲に維持することが困難である。また、燃焼温度が５００℃を超えると、触媒が劣化することがある。
【０００５】
凝縮回収法では、ＶＯＣガスの濃度が５０００ｐｐｍより高くないと、実用的な処理効率が得られない。
吸着除去法では、活性炭に吸着限度があるため、長期間の使用では大量の活性炭を必要とし、活性炭の吸着限度の管理が困難である。
【０００６】
本発明は、前記事情に鑑みてなされたもので、排ガス中に含まれる可燃性の揮発性有機化合物ガスを効率的に除去、分解する可燃性の揮発性有機化合物ガス処理装置、可燃性の揮発性有機化合物ガス処理システム、可燃性の揮発性有機化合物ガス処理方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
前記課題は、排ガスおよび冷却ガスを吸着部内に導入するガス導入部と、排ガス中の可燃性の揮発性有機化合物ガスを吸着する吸着部と、該吸着部内に酸素ガスを置換する置換ガスを供給する置換ガス供給部と、前記吸着部を加熱するとともに、前記吸着部から脱着された可燃性の揮発性有機化合物ガスを燃焼する加熱部と、前記吸着部内の可燃性の揮発性有機化合物ガス濃度、酸素ガス濃度および温度を検知する検知部とを備えた可燃性の揮発性有機化合物ガス処理装置によって解決できる。
前記加熱部は、前記吸着部を加熱する熱交換部と、前記吸着部から脱着された可燃性の揮発性有機化合物ガスを燃焼する燃焼部からなり、かつ、前記吸着部と一体化されていることが好ましい。
前記課題は、上記可燃性の揮発性有機化合物ガス処理装置を少なくとも２つ用いた可燃性の揮発性有機化合物ガス処理システムによって解決できる。
前記課題は、上記可燃性の揮発性有機化合物ガス処理装置を用いた可燃性の揮発性有機化合物ガス処理方法であって、ガス導入部から導入された排ガス中の可燃性の揮発性有機化合物ガスを前記吸着部で吸着除去する吸着過程と、可燃性の揮発性有機化合物ガスを吸着した吸着部内の雰囲気を酸素ガス濃度が８％未満の酸素欠乏雰囲気とする脱着準備過程と、酸素欠乏雰囲気下において、吸着部を加熱して可燃性の揮発性有機化合物ガスを脱着する脱着過程と、脱着された可燃性の揮発性有機化合物ガスを酸素ガス濃度８％以上の有酸素雰囲気中で燃焼させる燃焼過程と、可燃性の揮発性有機化合物ガスの燃焼終了後に吸着部を冷却する冷却過程とを有する可燃性の揮発性有機化合物ガス処理方法によって解決できる。
前記脱着準備過程において、窒素ガス、炭酸ガスおよび酸素を除去した空気のうち少なくとも１種類を前記吸着部内に送入し、酸素ガスを置換することが好ましい。
前記脱着過程において、前記吸着部を加熱する温度を１００〜８００℃とすることが好ましい。
前記燃焼過程において、前記吸着部から脱着された可燃性の揮発性有機化合物ガスを、前記吸着部から前記燃焼部へ送入し、燃焼分解することが好ましい。
前記燃焼過程において、可燃性の揮発性有機化合物が吸着部から脱着して気化する際の体積膨張、および加熱による可燃性の揮発性有機化合物ガスの体積熱膨張を推力として、前記吸着部から脱着された可燃性の揮発性有機化合物ガスの前記吸着部から前記燃焼部へ送入を行うことが好ましい。
前記燃焼過程において、前記吸着部から脱着された可燃性の揮発性有機化合物ガスの前記吸着部から前記燃焼部への送入を、前記置換ガス供給部から窒素ガス、炭酸ガスおよび酸素を除去した空気のうち少なくとも１種類を、可燃性の揮発性有機化合物ガスの燃焼中に断続的に前記吸着部内に送入するか、もしくは連続的にかつ送入量を減少あるいは増加させつつ送入するか、または、可燃性の揮発性有機化合物ガスの燃焼終了直前に前記吸着部内に送入することによって行うことが好ましい。
上記可燃性の揮発性有機化合物ガス処理方法において、前記吸着部内の可燃性の揮発性有機化合物ガス濃度を検知して、前記吸着過程から前記脱着準備過程への移行を制御し、前記燃焼過程から前記冷却過程への移行を制御し、前記燃焼過程における前記置換ガスの供給を制御することが好ましい。
上記可燃性の揮発性有機化合物ガス処理方法において、前記吸着部内の酸素ガス濃度を検知して、前記脱着準備過程から前記脱着過程への移行を制御することが好ましい。
上記可燃性の揮発性有機化合物ガス処理方法において、前記吸着部の温度を検知して、前記吸着部から可燃性の揮発性有機化合物ガスを脱着する際の前記吸着部の温度を制御することが好ましい。
【０００８】
【発明の実施の形態】
以下、本発明を詳しく説明する。
図１は、本発明の可燃性の揮発性有機化合物ガス処理装置の一例を模式的に示す概略構成図である。
図１において、符号１は、排ガスおよび冷却ガスを、後述の吸着部２内に導入するガス導入部を示し、矢印は液体および気体の流通方向を示す。このガス導入部１は逆止弁または開閉が制御可能な例えば電磁開閉弁などからなり、直接、吸着部２に接続されている。また、吸着部２には、収納部材（図示略）内に排ガス中の可燃性ＶＯＣガスを吸着する顆粒状の吸着材２０が充填されており、吸着部２を加熱する熱交換部３と、吸着部２から脱着された可燃性ＶＯＣガスを燃焼する燃焼器４ａとを備えた燃焼部４とからなる加熱部５と一体に形成されている。また、吸着部２には、この吸着部２内に酸素ガスを置換する置換ガスを供給する置換ガス供給部６が、ガス供給管路７および開閉弁８を介して接続されている。さらに、吸着部２には、燃焼部４の近傍に、吸着部２内の吸着材２０から脱着された可燃性ＶＯＣガスを燃焼部４へ放出する逆止弁などからなる脱着ガス放出部９が設けられている。そして、吸着部２には、吸着部２で可燃性ＶＯＣガスが吸着除去された排ガスを大気中に放出する逆止弁などからなる排ガス放出部１０が、この可燃性の揮発性有機化合物ガス処理装置の上部に設けられている。
また、吸着部２には、吸着部２内の可燃性ＶＯＣガス濃度、酸素ガス濃度および吸着部２の温度をモニタする検知部１１が設けられている。
また、加熱部５の燃焼部４には、燃焼部４で燃焼した可燃性ＶＯＣガスを排出する燃焼ガス排出部１２が連通するように、設けられている。さらに、燃焼ガス排出部１２には、可燃性ＶＯＣガスの燃焼ガス中に含まれる硫黄、塩素などの有害物質を中和除去する後処理部１３が接続されている。また、加熱部５の燃焼部４には、燃焼部４へ可燃性ＶＯＣガスを燃焼させるための燃料を供給する燃料供給部１４が、燃料供給管路１５を介して接続されている。
そして、この例の可燃性の揮発性有機化合物ガス処理装置には、上記の各部の動作をモニタし、その動作を制御するシーケンサを有する制御部１６が設けられている。
【０００９】
また、吸着部２と加熱部５は一体に形成されたチャンバ１７からなり、チャンバ１７の外形形状は、例えば、図１および図２（ａ）、（ｂ）に示すように円柱状となっている。この例のチャンバ１７では、中央に燃焼ガス排出部１２が配置され、これと中心軸を同じくする吸着部２および熱交換部３が設けられている。熱交換部３は、図２に示すように、吸着部２の間に設けられ、チャンバ１７の長手方向に、吸着部２とほぼ同じ長さで形成されている。熱交換部３の長手方向の長さを、吸着部２の長手方向の長さとほぼ同じとすることにより、熱交換部３による吸着部２の加熱を効率良く行うことができる。さらに、熱交換部３は、図２（ａ）に示すように円環状に形成されていても、図２（ｂ）に示すように複数の円管から構成されていてもよく、熱交換部３の数、大きさなどは、吸着部２の大きさ、熱効率などを考慮して、適宜設定される。また、熱交換部３は、熱伝導性の金属部品や抵抗型電熱器、誘導コイル型電熱器などで形成されている。
そして、燃焼部４は、チャンバ１７の下部に設けられており、吸着部２の下部に設けられた脱着ガス放出部９から放出される可燃性ＶＯＣガスを、効率良く燃焼できるようになっている。また、燃焼部４内に備えられた燃焼器４ａとしては、燃焼式バーナ、抵抗型電熱器、誘導コイル型電熱器、あるいはこれらを組み合せたものなどが用いられるが、この例では、燃焼式バーナを例示する。
【００１０】
また、燃焼ガス排出部１２は、チャンバ１７の中心部に、その上端部１２ａがチャンバ１７の上面１７ａから突出するように設けられた円筒形状のものである。このようにすれば、可燃性ＶＯＣガスの燃焼ガスの装置外への排出を効率良く行うことができる。さらに、燃焼ガス排出部１２は、燃焼部４と連通されており、燃焼部４で燃焼した可燃性ＶＯＣガスの排出を効率良く行うことができるようになっている。
なお、ここでは、各部の長手方向と垂直な断面形状が円形のチャンバ１７、および長手方向と垂直な断面形状が円形の燃焼ガス排出部１２を例示したが、本発明の可燃性の揮発性有機化合物ガス処理装置にあっては、チャンバ１７または燃焼ガス排出部１２の長手方向と垂直な断面形状は、四角形状、矩形状などであってもよい。
【００１１】
吸着部２の収納部材内に充填される顆粒状の吸着材２０としては、排ガス中の可燃性ＶＯＣガスを選択的に吸着することができる活性炭、ゼオライト、あるいは、撥水性および／または親油性セラミックの焼結体などの多孔質材が挙げられる。吸着材２０は、球形、円柱形、樽形、棒状となっているのが望ましいが、不定形のものでもよい。
吸着材２０は、その自重に応じた量の可燃性ＶＯＣを吸着することが可能である。したがって、想定される可燃性ＶＯＣガスの一回分の処理量に応じて、適宜、吸着材２０の使用量を決定すればよい。
【００１２】
なお、吸着部２は、上記のように顆粒状の吸着材２０が収納部材内に充填されたものに限らず、上記の多孔質体を膜状、板状、格子状などに形成したものであってもよい。
このような膜状、板状、格子状の吸着部２の大きさは、想定される可燃性ＶＯＣガスの一回分の処理量に応じて適宜決定される。
【００１３】
以下、本発明の可燃性の揮発性有機化合物ガス処理装置の動作を説明しながら、本発明の可燃性の揮発性有機化合物ガス処理方法について説明する。
まず、印刷・塗装工場、化学プラント、食品加工工場などから排出された、可燃性ＶＯＣガスを含む排ガスを、ガス導入管路１９およびガス導入部１を介して、吸着部２内に送入する。このとき、吸着部２内に送入する前に、あらかじめ、可燃性ＶＯＣガスを含む排ガスを、常温（４０℃以下）程度に冷却しておくことが好ましい。ガス導入部１は、排ガスを吸着部２内に導入するときには開放し、排ガスを導入しないときには閉じている。
次いで、吸着部２内に送入された排ガスが吸着部２内の吸着材２０に接触すると、排ガス中の可燃性ＶＯＣガスが、吸着材２０に選択的に吸着されて、除去される（吸着過程）。この吸着過程において、可燃性ＶＯＣガスが吸着除去された排ガスは、排ガス放出部１０から大気中に放出される。排ガス放出部１０は、排ガスを大気中に放出するときに開放し、排ガスを放出しないときには閉じている。この吸着過程において、可燃性ＶＯＣガスを含む排ガスの吸着部内への送入と、可燃性ＶＯＣガスが吸着除去された排ガスの放出を繰り返して、吸着部２の吸着材２０に、可燃性ＶＯＣガスを吸着限界まで吸着させる。
さらに、吸着過程では、吸着部２内の可燃性ＶＯＣガスの濃度を検知部１１によってモニタし、吸着材２０が可燃性ＶＯＣガスを吸着限界まで吸着したか判定する。
【００１４】
次いで、吸着部２の吸着材２０が可燃性ＶＯＣガスを吸着限界まで吸着した後、置換ガス供給部６から、ガス供給管路７および開閉弁８を介して、吸着部２内に、吸着部２内の酸素ガスを置換する置換ガスを供給して、吸着部２内の雰囲気を酸素ガス濃度が低くされた酸素欠乏雰囲気とする（脱着準備過程）。このとき、吸着部２内の雰囲気中の酸素ガス濃度を８体積％未満とし、好ましくは５体積％未満とする。吸着部２内の雰囲気中の酸素ガス濃度が８体積％以上では、吸着部２内の可燃性ＶＯＣガスが爆発下限を超えた場合、静電気などで可燃性ＶＯＣガスが爆発するおそれがある。このように、吸着部２内の雰囲気中の酸素ガス濃度を８体積％未満とすれば、爆発の危険を回避できるため、後段の脱着過程において、高温、高濃度の状態で可燃性ＶＯＣガスを脱着することができる。
また、置換ガス供給部６から吸着部２内に供給される置換ガスとしては、窒素ガス、炭酸ガスおよび酸素を除去した空気などの不活性なガスのうち少なくとも１種類を用いることが好ましい。これらの置換ガスを、酸素ガスと置換することにより、吸着部２内の可燃性ＶＯＣガスが爆発することを防止することができる。さらに、置換ガスの温度、流量および流速は、吸着材２０に吸着された可燃性ＶＯＣガスが揮発しない程度に、適宜設定される。
【００１５】
次いで、上述の酸素欠乏雰囲気下において、吸着部２内の吸着材２０を熱交換部３で直接加熱して、吸着材２０に吸着されている可燃性ＶＯＣガスを脱着する（脱着過程）。この脱着過程において、吸着部２の温度を検知部１１で検知して、吸着部２から可燃性ＶＯＣガスを脱着する際の吸着部２の温度を、制御部１６で制御する。このように、吸着部２の温度を検知部１１で直接測定することにより、後述のように、吸着部２の温度が低過ぎるか、あるいは高過ぎることによって生じる不具合を防止することができる。また、この脱着過程において、吸着部２内の吸着材２０を加熱する温度を好ましくは１００〜８００℃とし、特に好ましくは３００〜６００℃とする。吸着材２０を加熱する温度を上記範囲とすれば、吸着材２０から可燃性ＶＯＣガスを高濃度で、短時間に脱着することができる。
吸着材２０を加熱する温度が１００℃未満では、可燃性ＶＯＣガスを脱着するのに要する時間が長くなり、吸着材２０に吸着された可燃性ＶＯＣガスを完全に脱着できなくなるなど、脱着の効率が十分ではなくなる場合がある。吸着材２０を加熱する温度が８００℃を超えると、吸着材２０が熱劣化するおそれと、加温エネルギーの負荷が大きくなり不利である。
【００１６】
次いで、吸着部２から脱着された可燃性ＶＯＣガスを、吸着部２から脱着ガス放出部９を介して燃焼部４へ送入し、燃焼部４内の雰囲気を、酸素ガス濃度が８体積％以上、好ましくは１５体積％以上の有酸素雰囲気とし、この可燃性ＶＯＣガスを燃焼部４に備えられている燃焼式バーナからなる燃焼器４ａで燃焼し、分解する（燃焼過程）。このとき、燃焼器４ａには、燃料供給部１４から燃料供給管路１５を介して、可燃性ＶＯＣガスを燃焼するための燃料が供給される。
この燃焼過程において、燃焼部４内の雰囲気中の酸素ガス濃度が８体積％未満では、可燃性ＶＯＣガス濃度の燃焼効率が悪くなり、不完全燃焼となる。
【００１７】
また、この燃焼過程において、可燃性ＶＯＣが吸着部２から脱着されて気化する際の体積膨張、および加熱による可燃性ＶＯＣガスの体積熱膨張を推力として、吸着部２から脱着された可燃性ＶＯＣガスの吸着部２から燃焼部４へ送入を行う。
このように可燃性ＶＯＣの体積熱膨張を推力とすれば、逆止弁などからなる脱着ガス放出部９を開放するだけで、可燃性ＶＯＣガスが吸着部２から燃焼部４へと自動的に送入される。
【００１８】
さらに、この燃焼過程において、吸着部２から脱着された可燃性ＶＯＣガスの吸着部２から燃焼部４へ送入を、置換ガス供給部６から窒素ガス、炭酸ガス、酸素を除去した空気のうち少なくとも１種類を、可燃性ＶＯＣガスの燃焼中に断続的に吸着部２内に送入するか、または、可燃性ＶＯＣガスの燃焼終了直前に吸着部２内に送入することによって行ってもよい。このとき、置換ガスの流量および流速は、可燃性ＶＯＣガスの量、燃焼部４における燃焼効率などを考慮して、適宜設定される。
この方法によれば、置換ガスの送入により、強制的に可燃性ＶＯＣガスが吸着部２から燃焼部４へと送入されるから、可燃性ＶＯＣの体積熱膨張のみを推力とした場合よりも、効率良く送入される。さらに、吸着材２０から脱着された可燃性ＶＯＣガスを吸着部２内に残留することなく、燃焼部４に送入することができる。
【００１９】
次いで、可燃性ＶＯＣガスの燃焼ガスを、燃焼ガス排出部１２を経由して、後処理部１３内に送入し、この燃焼ガス中に含まれている硫黄、塩素などの有害物質を、吸収、吸着または中和して除去する（後処理過程）。次いで、後処理部１３で、硫黄、塩素などの有害物質が除去されて無害化された燃焼ガスは、後処理部１３から、大気中へと放出される。
この後処理過程において、硫黄、塩素などの有害物質を、吸収、吸着または中和する処理剤としては、例えば、亜硫酸カルシウム、ケイ酸カルシウム、炭酸ナトリウム、重炭酸ナトリウム、チオ硫酸ナトリウム、炭酸カルシウム、石灰、アンモニア、苛性ソーダ、アルカリイオン水、水などの中から選択される１種または２種以上を含むアルカリ性イオン水などが用いられる。
【００２０】
また、可燃性ＶＯＣガスの燃焼終了後に、ガス導入部１から吸着部２内に冷却ガスを送入し、吸着部２内の吸着材２０を冷却する（冷却過程）。冷却ガスとしては、窒素ガス、炭酸ガス、空気などが用いられる。吸着材２０を冷却する温度は、４０℃以下となるようにすることが好ましい。
可燃性ＶＯＣガスは低温であるほど、吸着され易くなる。そこで、吸着部２から脱着された可燃性ＶＯＣガスの燃焼が終了する毎に、吸着部２内の吸着材２０を冷却することにより、吸着材２０が可燃性ＶＯＣガスを吸着する量を多することができる。
【００２１】
本発明の可燃性の揮発性有機化合物ガス処理方法では、吸着部２内の可燃性ＶＯＣガス濃度を検知部１１で検知して、吸着過程から脱着準備過程への移行、燃焼過程から冷却過程への移行、燃焼過程における置換ガスの供給を制御する。さらに、吸着部２内の酸素ガス濃度を検知部１１で検知して、脱着準備過程から脱着過程への移行を制御する。
本発明の可燃性の揮発性有機化合物ガス処理方法にあっては、吸着部２内の可燃性ＶＯＣガス濃度または酸素ガス濃度の検知結果に基づいて、制御部１６によって各部の制御を行うことができるから、上記の前段の処理過程から、後段の処理過程への移行を自動で行うことができる。また、吸着部２内の可燃性ＶＯＣガス濃度または酸素ガス濃度の検知によって、処理過程が移行するから、各処理過程において処理の完了したことを容易に確認することができる。
【００２２】
また、本発明の可燃性の揮発性有機化合物ガス処理システムは、本発明の可燃性の揮発性有機化合物ガス処理装置と同様の構造を有するガス処理装置を少なくとも２つ組み合わされてなるものである。
図３は、本発明の可燃性の揮発性有機化合物ガス処理システムの一例を模式的に示す図である。
この例では、可燃性の揮発性有機化合物ガス処理システムが、本発明の可燃性の揮発性有機化合物ガス処理装置と同様の構造を有するがガス処理装置が２つ組み合わされたものとする。
【００２３】
この例の可燃性の揮発性有機化合物ガス処理システムは、可燃性ＶＯＣガスを吸着および脱着する第１の吸脱着塔２１、第２の吸脱着塔２２と、これらのそれぞれに一体に設けられた加熱部２３、２４と、加熱部２３、２４に燃料を供給する燃料供給部２５と、第１の吸脱着塔２１内および第２の吸脱着塔２２内に酸素ガスと置換する不活性ガスを供給する不活性ガス供給部２６と、これら各部の動作をモニタし、その動作を制御する制御部２７とから概略構成されている。
【００２４】
次に、この例の可燃性の揮発性有機化合物ガス処理システムの動作例を説明する。
この例では、第１の吸脱着塔２１が排ガス中の可燃性ＶＯＣガスを吸着する処理を行う状態（吸着モード）であり、第２の吸脱着塔２２が、この吸脱着塔内に備えられた吸着部に吸着された可燃性ＶＯＣガスを脱着、燃焼する処理を行う状態（脱着、燃焼モード）である。
【００２５】
（吸着モード）
まず、吸着モードの第１の吸脱着塔２１において、バルブ２８を開放し、可燃性ＶＯＣガスを含む排ガスを、第１の吸脱着塔２１内の吸着部へ送入する。このとき、第１の吸脱着塔２１と不活性ガス供給部２６と連結する配管に設けられたバルブ２９は閉じておく。
次いで、可燃性ＶＯＣガスが吸着除去された排ガスは、第１の吸脱着塔２１から、連絡管３０を介して、加熱部２３に送入され、ここから大気中に放出される。このとき、燃料供給バルブ３１は閉じており、燃料供給２５から加熱部２３への燃料の供給は行われずに、加熱部２３内に備えられた燃焼式バーナは休止している。
【００２６】
（脱着、燃焼モード）
まず、第２の吸脱着塔２２内の吸着部に備えられた吸着材が、吸着限界まで可燃性ＶＯＣガスを吸着したら、バルブ３２を閉じて、可燃性ＶＯＣガスを含む排ガスの第２の吸脱着塔２２内への送入を停止する。
次いで、第２の吸脱着塔２２と不活性ガス供給部２６と連結する配管に設けられたバルブ３３を開放し、第２の吸脱着塔２２の吸着部内の雰囲気中の酸素ガス濃度が８体積％未満となるまで、不活性ガス供給部２６から第２の吸脱着塔２２の吸着部内に不活性ガスを送入する。
次いで、燃料供給バルブ３５を開放して、加熱部２３内に備えられた燃焼式バーナを点火し、第２の吸脱着塔２２を加熱する。
次いで、加熱された第２の吸脱着塔２２の吸着部内に備えられた吸着材から可燃性ＶＯＣガスが脱着して、連絡管３４を介して加熱部２４に送入され、加熱部２３内に備えられた燃焼式バーナで燃焼される。
次いで、燃焼処理された可燃性ＶＯＣガスの排ガスは、後処理過程によって、硫黄、塩素などの有害物質が除去された後、大気中に放出される
この脱着、燃焼モードにおいては、あらかじめプログラムされた順序にしたがって、バルブ３３が制御部２７によって自動的に開放され、不活性ガス供給部２６から第２の吸脱着塔２２内へ不活性ガスが送入される。
次いで、第２の吸脱着塔２２の吸着部内の可燃性ＶＯＣガス濃度が所定濃度以下になると、燃料供給バルブ３５を閉じて、加熱部２３内に備えられた燃焼式バーナを停止する。
次いで、バーナ停止後、自然放置もしくは大気送入により冷却し、第２の吸脱着塔２２内の温度が４０℃未満になったら、吸着モードへ移行する。
【００２７】
この例の可燃性の揮発性有機化合物ガス処理システムを用いた可燃性の揮発性有機化合物ガス処理方法では、第１の吸脱着塔２１の吸着部内および第２の吸脱着塔２２の吸着部内の可燃性ＶＯＣガス濃度、酸素ガス濃度および温度を検知部３６、３７で検知し、その結果を制御部２７でモニタして、各バルブの開閉の制御を行う。これにより、各処理過程における後段の処理過程への移行を自動的に行うことができる上に、上記「吸着モード」から「脱着、燃焼モード」への移行も自動的に行うことができる。さらに、各処理過程において処理の完了したことを容易に確認することができる。
また、上記「吸着モード」と「脱着、燃焼モード」を、第１の吸脱着塔２１と第２の吸脱着塔２２で交互に実施することで、常時、排ガスに含まれる可燃性ＶＯＣガスの処理が可能となり、効率良く可燃性ＶＯＣガスの処理することができる。
【００２８】
なお、本発明の可燃性の揮発性有機化合物ガス処理システムにあっては、本発明の可燃性の揮発性有機化合物ガス処理装置と同様の構造を有するがガス処理装置（この例では、第１の吸脱着塔２１、第２の吸脱着塔２２。）を、さらに多く（３つ以上）組み合わせて用いれば、より効率良く、排ガスに含まれる可燃性ＶＯＣガスの処理を行うことができる。
【００２９】
【発明の効果】
以上説明したように、本発明の可燃性の揮発性有機化合物ガス処理装置によれば、吸着部を直近から燃焼部で加熱するため、エネルギー効率を大幅に改善できる。
本発明の可燃性の揮発性有機化合物ガス処理システムによれば、常時、可燃性ＶＯＣガスの処理が可能となる。
本発明の可燃性の揮発性有機化合物ガス処理方法によれば、可燃性ＶＯＣガスを高温、高濃度の状態で脱着を可能とし、脱着時間を短縮できる。その結果、可燃性ＶＯＣガスの脱着に要する加熱エネルギーを最小化できる。また、可燃性ＶＯＣガスの脱着するための置換ガスの送入量を大幅に削減することができる。さらに、可燃性ＶＯＣガスの脱着温度を高温にすることが可能であるから、吸着材に吸着された難揮発性の可燃性ＶＯＣまで気化することができるため、その結果として、可燃性ＶＯＣガスの吸着量および脱着量を大きく持続できるため、吸着材の使用量を最小化できる。そして、吸着部内のガス濃度を検知することで、一連の処理過程を自動化できる。
【図面の簡単な説明】
【図１】本発明の可燃性の揮発性有機化合物ガス処理装置の一例を模式的に示す概略構成図である。
【図２】本発明の可燃性の揮発性有機化合物ガス処理装置を構成するチャンバの構造を示す概略図である。
【図３】本発明の可燃性の揮発性有機化合物ガス処理システムの一例を模式的に示す図である。
【符号の説明】
１・・・ガス導入部、２・・・吸着部、３・・・熱交換部、４・・・燃焼部、４ａ・・・燃焼器、５・・・加熱部、６・・・置換ガス供給部、７・・・ガス供給管路、８・・・開閉弁、９・・・脱着ガス放出部、１０・・・排ガス放出部、１１・・・検知部、１２・・・燃焼ガス排出部、１３・・・後処理部、１４・・・燃料供給部、１５・・・燃料供給管路、１６・・・制御部、１７・・・チャンバ、１９・・・ガス導入管路、２０・・・吸着材、２１・・・第１の吸脱着塔、２２・・・第２の吸脱着塔、２３，２４・・・加熱部、２５・・・燃料供給部、２６・・・不活性ガス供給部、２７・・・制御部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a flammable volatile organic compound gas treatment device that efficiently removes and decomposes flammable volatile organic compound gas contained in exhaust gas, a flammable volatile organic compound gas treatment system, The present invention relates to a method for treating volatile organic compound gas.
[0002]
[Prior art]
2. Description of the Related Art In the past, flammable volatile organic compounds (Volatile Organic Compounds, hereinafter sometimes abbreviated as “VOC”) such as benzene and toluene have been widely used in printing / painting plants, chemical plants, food processing industries, and the like. Was.
In recent years, since the Air Pollution Control Law has designated a part of VOCs as harmful air pollutants as priority acquisition substances and self-managed substances, the amount of VOC gas contained in exhaust gas discharged from factories etc. has been released. Various methods of treating VOC gas have been devised in order to keep the level below the standard.
[0003]
As a method of treating the VOC gas, a direct combustion method in which the discharged VOC gas is directly burned and decomposed in a combustion furnace (Japanese Patent Laid-Open No. 11-82879), a catalytic combustion in which the discharged VOC gas is burned and decomposed in a catalytic combustion furnace (JP-A-10-267928, JP-A-2001-90931), a condensed recovery method in which discharged VOC gas is compressed and recovered by a condensed liquefaction method, and an adsorption removal method in which discharged VOC gas is adsorbed on activated carbon and purified. (Japanese Unexamined Patent Publication No. Hei 7-289843).
[0004]
[Problems to be solved by the invention]
However, in the direct combustion method, when the concentration of the VOC gas in the exhaust gas is less than 800 ppm, the fuel efficiency in the combustion of the VOC gas is extremely poor and is not practical. If the concentration of the VOC gas is higher than the lower explosion limit, explosion-proof measures are required.
In the catalytic combustion method, when the concentration of the VOC gas in the exhaust gas is less than 200 ppm, it is difficult to maintain the catalytic combustion temperature in an appropriate temperature range only by the self-combustion of the VOC gas. If the combustion temperature exceeds 500 ° C., the catalyst may deteriorate.
[0005]
In the condensation recovery method, unless the concentration of the VOC gas is higher than 5000 ppm, practical treatment efficiency cannot be obtained.
In the adsorption removal method, since activated carbon has an adsorption limit, a long-term use requires a large amount of activated carbon, and it is difficult to control the adsorption limit of activated carbon.
[0006]
The present invention has been made in view of the above circumstances, and has a flammable volatile organic compound gas processing device that efficiently removes and decomposes flammable volatile organic compound gas contained in exhaust gas. An object of the present invention is to provide a system for treating a volatile organic compound gas and a method for treating a flammable volatile organic compound gas.
[0007]
[Means for Solving the Problems]
The object is to provide a gas introduction unit for introducing exhaust gas and cooling gas into an adsorption unit, an adsorption unit for adsorbing flammable volatile organic compound gas in exhaust gas, and a replacement gas for replacing oxygen gas in the adsorption unit. A replacement gas supply unit, a heating unit that heats the adsorption unit and burns the combustible volatile organic compound gas desorbed from the adsorption unit, and a concentration of the combustible volatile organic compound gas in the adsorption unit. A flammable volatile organic compound gas processing apparatus provided with a detector for detecting the concentration and temperature of oxygen gas and temperature.
The heating unit includes a heat exchange unit that heats the adsorption unit and a combustion unit that burns the combustible volatile organic compound gas desorbed from the adsorption unit, and is integrated with the adsorption unit. Is preferred.
The object can be achieved by a flammable volatile organic compound gas processing system using at least two flammable volatile organic compound gas processing apparatuses.
The object is a method for treating a flammable volatile organic compound gas using the apparatus for treating a flammable volatile organic compound gas, wherein the flammable volatile organic compound gas in an exhaust gas introduced from a gas introduction unit is provided. An adsorption step of adsorbing and removing odors in the adsorption section, a desorption preparation step in which the atmosphere in the adsorption section adsorbing the flammable volatile organic compound gas is an oxygen-deficient atmosphere having an oxygen gas concentration of less than 8%, A desorption process of heating the adsorption section to desorb the flammable volatile organic compound gas, and burning the desorbed flammable volatile organic compound gas in an oxygen-containing atmosphere having an oxygen gas concentration of 8% or more. The problem can be solved by a method for treating a flammable volatile organic compound gas having a process and a cooling process of cooling the adsorbing section after completion of burning of the flammable volatile organic compound gas.
In the desorption preparation step, it is preferable that at least one of nitrogen gas, carbon dioxide gas and air from which oxygen has been removed is sent into the adsorption section to replace the oxygen gas.
In the desorption process, it is preferable that a temperature at which the adsorption section is heated is 100 to 800 ° C.
In the combustion process, it is preferable that the combustible volatile organic compound gas desorbed from the adsorbing section is sent from the adsorbing section to the combustion section, and is decomposed by combustion.
In the combustion process, the flammable volatile organic compound is desorbed from the adsorbing section by using the volume expansion when the flammable volatile organic compound is desorbed and vaporized from the adsorbing section and the volumetric thermal expansion of the flammable volatile organic compound gas by heating as a thrust It is preferable that the combustible volatile organic compound gas is sent from the adsorption section to the combustion section.
In the combustion process, the supply of the flammable volatile organic compound gas desorbed from the adsorption section to the combustion section from the adsorption section and the nitrogen gas, carbon dioxide gas, and oxygen were removed from the replacement gas supply section. Whether at least one of the air is intermittently fed into the adsorbing section during the combustion of the flammable volatile organic compound gas, or whether it is fed continuously and with a reduced or increased amount of air Alternatively, it is preferable that the gas is sent into the adsorption section immediately before the end of the combustion of the combustible volatile organic compound gas.
In the method for treating a flammable volatile organic compound gas, the concentration of the flammable volatile organic compound gas in the adsorption section is detected, and a transition from the adsorption step to the desorption preparation step is controlled. It is preferable to control the transition to the cooling process and control the supply of the replacement gas in the combustion process.
In the method for treating a flammable volatile organic compound gas, it is preferable that a transition from the desorption preparation process to the desorption process is controlled by detecting an oxygen gas concentration in the adsorption section.
In the method for treating a flammable volatile organic compound gas, it is possible to detect a temperature of the adsorption section and control a temperature of the adsorption section when desorbing the flammable volatile organic compound gas from the adsorption section. preferable.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
FIG. 1 is a schematic configuration diagram schematically showing an example of the flammable volatile organic compound gas treatment apparatus of the present invention.
In FIG. 1, reference numeral 1 denotes a gas introduction unit that introduces exhaust gas and cooling gas into an adsorption unit 2 described later, and arrows indicate flow directions of a liquid and a gas. The gas introduction unit 1 is composed of a check valve or an open / close controllable solenoid valve, for example, and is directly connected to the adsorption unit 2. Further, the adsorbing section 2 is filled with a granular adsorbent 20 for adsorbing combustible VOC gas in exhaust gas in a storage member (not shown), and a heat exchange section 3 for heating the adsorbing section 2; It is formed integrally with a heating section 5 comprising a combustion section 4 having a combustor 4a for burning the combustible VOC gas desorbed from the adsorption section 2. Further, a replacement gas supply unit 6 for supplying a replacement gas for replacing oxygen gas into the adsorption unit 2 is connected to the adsorption unit 2 via a gas supply pipe 7 and an on-off valve 8. Further, in the adsorbing section 2, a desorbing gas releasing section 9 including a check valve for releasing the combustible VOC gas desorbed from the adsorbing material 20 in the adsorbing section 2 to the burning section 4 is provided near the combustion section 4. Is provided. The adsorbing section 2 is provided with an exhaust gas discharging section 10 including a check valve for releasing the exhaust gas from which the combustible VOC gas has been adsorbed and removed by the adsorbing section 2 into the atmosphere. It is provided at the top of the device.
Further, the adsorption unit 2 is provided with a detection unit 11 that monitors the flammable VOC gas concentration, the oxygen gas concentration and the temperature of the adsorption unit 2 in the adsorption unit 2.
Further, the combustion part 4 of the heating part 5 is provided so as to communicate with a combustion gas discharge part 12 for discharging the combustible VOC gas burned in the combustion part 4. Further, a post-processing unit 13 for neutralizing and removing harmful substances such as sulfur and chlorine contained in the combustion gas of the combustible VOC gas is connected to the combustion gas discharge unit 12. Further, a fuel supply unit 14 that supplies fuel for burning combustible VOC gas to the combustion unit 4 is connected to the combustion unit 4 of the heating unit 5 via a fuel supply pipe 15.
Further, the combustible volatile organic compound gas processing apparatus of this example is provided with a control unit 16 having a sequencer for monitoring the operation of each unit described above and controlling the operation.
[0009]
The adsorbing section 2 and the heating section 5 are integrally formed with a chamber 17, and the outer shape of the chamber 17 is, for example, cylindrical as shown in FIGS. 1 and 2A and 2B. I have. In the chamber 17 of this example, the combustion gas discharge unit 12 is disposed at the center, and the adsorption unit 2 and the heat exchange unit 3 having the same central axis as the combustion gas discharge unit 12 are provided. As shown in FIG. 2, the heat exchange section 3 is provided between the adsorption sections 2, and is formed in the longitudinal direction of the chamber 17 with substantially the same length as the adsorption section 2. By setting the length of the heat exchange unit 3 in the longitudinal direction to be substantially the same as the length of the adsorption unit 2 in the longitudinal direction, the heat exchange unit 3 can efficiently heat the adsorption unit 2. Further, the heat exchange section 3 may be formed in an annular shape as shown in FIG. 2 (a) or may be composed of a plurality of circular tubes as shown in FIG. 2 (b). The number, size, and the like of 3 are appropriately set in consideration of the size, thermal efficiency, and the like of the suction unit 2. Further, the heat exchange section 3 is formed of a heat conductive metal part, a resistance type electric heater, an induction coil type electric heater, or the like.
The combustion section 4 is provided below the chamber 17 so that the combustible VOC gas released from the desorption gas release section 9 provided below the adsorption section 2 can be efficiently burned. . As the combustor 4a provided in the combustion section 4, a combustion type burner, a resistance type electric heater, an induction coil type electric heater, or a combination thereof is used. In this example, a combustion type burner is used. Is exemplified.
[0010]
Further, the combustion gas discharge section 12 has a cylindrical shape provided at the center of the chamber 17 so that the upper end 12 a protrudes from the upper surface 17 a of the chamber 17. This makes it possible to efficiently discharge the combustible VOC gas out of the apparatus. Further, the combustion gas discharge section 12 is connected to the combustion section 4 so that the combustible VOC gas burned in the combustion section 4 can be efficiently discharged.
Here, the chamber 17 having a circular cross section perpendicular to the longitudinal direction of each section and the combustion gas discharge section 12 having a circular cross section perpendicular to the longitudinal direction are illustrated as examples. In the compound gas processing apparatus, the cross-sectional shape perpendicular to the longitudinal direction of the chamber 17 or the combustion gas discharge unit 12 may be a square shape, a rectangular shape, or the like.
[0011]
As the granular adsorbent 20 filled in the storage member of the adsorbing section 2, activated carbon, zeolite, or water-repellent and / or lipophilic ceramic capable of selectively adsorbing combustible VOC gas in exhaust gas is used. And a porous material such as a sintered body. The adsorbent 20 is preferably spherical, cylindrical, barrel, or rod-shaped, but may be irregular.
The adsorbent 20 can adsorb a combustible VOC in an amount corresponding to its own weight. Therefore, the usage amount of the adsorbent 20 may be appropriately determined according to the assumed processing amount of the combustible VOC gas for one time.
[0012]
The adsorbing section 2 is not limited to the one in which the granular adsorbent 20 is filled in the storage member as described above, and the above-described porous body is formed in a film shape, a plate shape, a lattice shape, or the like. There may be.
The size of the film-shaped, plate-shaped, or lattice-shaped adsorption portion 2 is appropriately determined in accordance with an assumed processing amount of the combustible VOC gas in one batch.
[0013]
Hereinafter, the method for treating a flammable volatile organic compound gas of the present invention will be described while describing the operation of the flammable volatile organic compound gas treating apparatus of the present invention.
First, exhaust gas containing flammable VOC gas discharged from a printing / painting factory, a chemical plant, a food processing factory, or the like is sent into the adsorption unit 2 via the gas introduction pipe 19 and the gas introduction unit 1. . At this time, it is preferable that the exhaust gas containing the flammable VOC gas is cooled to about room temperature (40 ° C. or less) in advance before being sent into the adsorption section 2. The gas introduction unit 1 is open when exhaust gas is introduced into the adsorption unit 2, and is closed when exhaust gas is not introduced.
Next, when the exhaust gas sent into the adsorption section 2 comes into contact with the adsorbent 20 in the adsorption section 2, the combustible VOC gas in the exhaust gas is selectively adsorbed by the adsorbent 20 and removed (adsorption). process). In this adsorption process, the exhaust gas from which the combustible VOC gas has been adsorbed and removed is discharged from the exhaust gas discharge unit 10 into the atmosphere. The exhaust gas discharging unit 10 is open when discharging the exhaust gas into the atmosphere, and is closed when not discharging the exhaust gas. In this adsorption process, the feeding of the exhaust gas containing the flammable VOC gas into the adsorption section and the release of the exhaust gas from which the flammable VOC gas has been adsorbed and removed are repeated, and the flammable VOC gas is supplied to the adsorbent 20 of the adsorption section 2. To the adsorption limit.
Further, in the adsorption process, the concentration of the flammable VOC gas in the adsorption unit 2 is monitored by the detection unit 11 to determine whether the adsorbent 20 has adsorbed the flammable VOC gas to the adsorption limit.
[0014]
Next, after the adsorbent 20 of the adsorbing section 2 adsorbs the combustible VOC gas to the adsorbing limit, the adsorbing section 2 supplies the adsorbing section 2 with the adsorbing section 2 through the gas supply pipe 7 and the on-off valve 8. A replacement gas for replacing the oxygen gas in the gas supply unit 2 is supplied, and the atmosphere in the adsorption unit 2 is changed to an oxygen-deficient atmosphere having a low oxygen gas concentration (desorption preparation process). At this time, the oxygen gas concentration in the atmosphere in the adsorbing section 2 is set to less than 8% by volume, preferably less than 5% by volume. When the concentration of oxygen gas in the atmosphere in the adsorbing section 2 is 8% by volume or more, if the combustible VOC gas in the adsorbing section 2 exceeds the lower limit of explosion, the combustible VOC gas may explode due to static electricity or the like. As described above, if the oxygen gas concentration in the atmosphere in the adsorption section 2 is less than 8% by volume, the danger of explosion can be avoided, so that the flammable VOC gas is removed at a high temperature and high concentration in the subsequent desorption process. Can be detached.
As the replacement gas supplied from the replacement gas supply unit 6 into the adsorption unit 2, it is preferable to use at least one of inert gases such as nitrogen gas, carbon dioxide gas, and air from which oxygen has been removed. By replacing these replacement gases with oxygen gas, it is possible to prevent the combustible VOC gas in the adsorption section 2 from exploding. Further, the temperature, flow rate, and flow rate of the replacement gas are appropriately set to such an extent that the combustible VOC gas adsorbed on the adsorbent 20 does not volatilize.
[0015]
Next, the adsorbent 20 in the adsorber 2 is directly heated by the heat exchange unit 3 in the above-described oxygen-deficient atmosphere to desorb the combustible VOC gas adsorbed by the adsorbent 20 (desorption process). In this desorption process, the temperature of the adsorption unit 2 is detected by the detection unit 11, and the temperature of the adsorption unit 2 when the combustible VOC gas is desorbed from the adsorption unit 2 is controlled by the control unit 16. As described above, by directly measuring the temperature of the suction unit 2 by the detection unit 11, it is possible to prevent a problem caused by the temperature of the suction unit 2 being too low or too high, as described later. In this desorption process, the temperature at which the adsorbent 20 in the adsorbing section 2 is heated is preferably 100 to 800 ° C, particularly preferably 300 to 600 ° C. When the temperature at which the adsorbent 20 is heated is within the above range, the combustible VOC gas can be desorbed from the adsorbent 20 at a high concentration in a short time.
If the temperature at which the adsorbent 20 is heated is lower than 100 ° C., the time required for desorbing the combustible VOC gas becomes long, and the decombustion VOC gas adsorbed on the adsorbent 20 cannot be completely desorbed. May not be enough. If the temperature at which the adsorbent 20 is heated exceeds 800 ° C., the adsorbent 20 may be thermally degraded, and the load of heating energy is increased, which is disadvantageous.
[0016]
Next, the combustible VOC gas desorbed from the adsorption unit 2 is sent from the adsorption unit 2 to the combustion unit 4 via the desorption gas discharge unit 9, and the atmosphere in the combustion unit 4 is set to an oxygen gas concentration of 8% by volume. As described above, the flammable VOC gas is burned in a combustor 4a composed of a combustion type burner provided in the combustion unit 4 and is decomposed (preferably a combustion process). At this time, the fuel for burning the combustible VOC gas is supplied to the combustor 4 a from the fuel supply unit 14 via the fuel supply pipe 15.
In this combustion process, if the oxygen gas concentration in the atmosphere in the combustion section 4 is less than 8% by volume, the combustion efficiency of the flammable VOC gas concentration deteriorates, resulting in incomplete combustion.
[0017]
In this combustion process, the flammable VOC desorbed from the adsorbing section 2 is used as a thrust by the volume expansion when the flammable VOC is desorbed and vaporized from the adsorbing section 2 and the volume thermal expansion of the flammable VOC gas by heating. The gas is sent from the adsorption section 2 to the combustion section 4.
If the volumetric thermal expansion of the flammable VOC is used as the thrust as described above, the flammable VOC gas is automatically transferred from the adsorption unit 2 to the combustion unit 4 simply by opening the desorption gas discharge unit 9 such as a check valve. Will be sent.
[0018]
Further, in this combustion process, the combustible VOC gas desorbed from the adsorbing section 2 is sent from the adsorbing section 2 to the combustion section 4, and the combustible VOC gas is removed from the air from which the nitrogen gas, carbon dioxide gas, and oxygen have been removed from the replacement gas supply section 6. At least one type may be intermittently fed into the adsorption section 2 during the combustion of the combustible VOC gas, or may be sent into the adsorption section 2 immediately before the end of the combustion of the combustible VOC gas. Good. At this time, the flow rate and the flow rate of the replacement gas are appropriately set in consideration of the amount of the combustible VOC gas, the combustion efficiency in the combustion section 4, and the like.
According to this method, the flammable VOC gas is forcibly fed from the adsorption unit 2 to the combustion unit 4 by the introduction of the replacement gas, so that only the volumetric thermal expansion of the flammable VOC is used as the thrust. Are also sent efficiently. Further, the combustible VOC gas desorbed from the adsorbent 20 can be sent to the combustion unit 4 without remaining in the adsorption unit 2.
[0019]
Next, the combustion gas of the combustible VOC gas is sent into the post-processing unit 13 via the combustion gas discharge unit 12 to absorb harmful substances such as sulfur and chlorine contained in the combustion gas. , Adsorption or neutralization to remove (post-treatment process). Next, the combustion gas detoxified by removing harmful substances such as sulfur and chlorine in the post-processing unit 13 is discharged from the post-processing unit 13 into the atmosphere.
In this post-treatment process, as a treating agent for absorbing, adsorbing or neutralizing harmful substances such as sulfur and chlorine, for example, calcium sulfite, calcium silicate, sodium carbonate, sodium bicarbonate, sodium thiosulfate, calcium carbonate, Alkaline ionized water containing one or more selected from lime, ammonia, caustic soda, alkaline ionized water, water and the like is used.
[0020]
Further, after the combustible VOC gas has been burned, a cooling gas is sent from the gas introduction unit 1 into the adsorption unit 2 to cool the adsorbent 20 in the adsorption unit 2 (cooling process). As the cooling gas, nitrogen gas, carbon dioxide gas, air or the like is used. It is preferable that the temperature at which the adsorbent 20 is cooled be 40 ° C. or lower.
The lower the temperature of the combustible VOC gas, the easier it is to be adsorbed. Therefore, every time the combustion of the combustible VOC gas desorbed from the adsorbing section 2 ends, the adsorbent 20 in the adsorbing section 2 is cooled to increase the amount of the adsorbent 20 adsorbing the combustible VOC gas. be able to.
[0021]
In the method for treating a flammable volatile organic compound gas of the present invention, the concentration of the flammable VOC gas in the adsorption section 2 is detected by the detection section 11, and the transition from the adsorption step to the desorption preparation step, and the combustion step to the cooling step. And the supply of replacement gas in the combustion process. Further, the detection unit 11 detects the oxygen gas concentration in the adsorption unit 2, and controls the transition from the desorption preparation process to the desorption process.
In the method for treating a flammable volatile organic compound gas of the present invention, the control unit 16 may control each unit based on the detection result of the flammable VOC gas concentration or the oxygen gas concentration in the adsorption unit 2. Therefore, it is possible to automatically perform the transition from the above-mentioned first-stage processing to the second-stage processing. Further, by detecting the concentration of the flammable VOC gas or the concentration of oxygen gas in the adsorption section 2, the processing steps are shifted, so that it is possible to easily confirm that the processing is completed in each processing step.
[0022]
Further, the flammable volatile organic compound gas processing system of the present invention is obtained by combining at least two gas processing apparatuses having the same structure as the flammable volatile organic compound gas processing apparatus of the present invention. .
FIG. 3 is a diagram schematically showing an example of the flammable volatile organic compound gas treatment system of the present invention.
In this example, it is assumed that the combustible volatile organic compound gas treatment system has the same structure as the combustible volatile organic compound gas treatment apparatus of the present invention, but two gas treatment apparatuses are combined.
[0023]
The flammable volatile organic compound gas treatment system of this example is provided integrally with a first adsorption / desorption tower 21 and a second adsorption / desorption tower 22 for adsorbing and desorbing a flammable VOC gas, respectively. Heating units 23 and 24, a fuel supply unit 25 that supplies fuel to the heating units 23 and 24, and an inert gas that replaces oxygen gas in the first adsorption / desorption tower 21 and the second adsorption / desorption tower 22. It is roughly composed of an inert gas supply unit 26 for supplying, and a control unit 27 for monitoring the operation of each unit and controlling the operation.
[0024]
Next, an operation example of the flammable volatile organic compound gas processing system of this example will be described.
In this example, the first adsorption / desorption tower 21 is in a state of performing a process of adsorbing the combustible VOC gas in the exhaust gas (adsorption mode), and the second adsorption / desorption tower 22 is provided in the adsorption / desorption tower. This is a state in which a process of desorbing and burning the combustible VOC gas adsorbed by the adsorbing section (desorption, combustion mode).
[0025]
(Suction mode)
First, in the first adsorption / desorption tower 21 in the adsorption mode, the valve 28 is opened, and the exhaust gas containing the combustible VOC gas is sent to the adsorption section in the first adsorption / desorption tower 21. At this time, the valve 29 provided on the pipe connecting the first adsorption / desorption tower 21 and the inert gas supply unit 26 is closed.
Next, the exhaust gas from which the combustible VOC gas has been adsorbed and removed is sent from the first adsorption / desorption tower 21 to the heating section 23 via the communication pipe 30, and is discharged therefrom to the atmosphere. At this time, the fuel supply valve 31 is closed, the fuel supply from the fuel supply 25 to the heating unit 23 is not performed, and the combustion type burner provided in the heating unit 23 is stopped.
[0026]
(Desorption, combustion mode)
First, when the adsorbent provided in the adsorbing section in the second adsorption / desorption tower 22 adsorbs the flammable VOC gas to the adsorption limit, the valve 32 is closed to perform the second adsorption of the exhaust gas containing the flammable VOC gas. The feeding into the desorption tower 22 is stopped.
Next, the valve 33 provided in the pipe connecting the second adsorption / desorption tower 22 and the inert gas supply unit 26 is opened, and the oxygen gas concentration in the atmosphere in the adsorption unit of the second adsorption / desorption tower 22 becomes 8 volume. %, The inert gas is fed from the inert gas supply unit 26 into the adsorption unit of the second adsorption / desorption tower 22 until the concentration becomes less than 10%.
Next, the fuel supply valve 35 is opened, the combustion type burner provided in the heating unit 23 is ignited, and the second adsorption / desorption tower 22 is heated.
Next, the combustible VOC gas is desorbed from the adsorbent provided in the heated adsorption / desorption tower of the second adsorption / desorption tower 22, is sent to the heating unit 24 through the communication pipe 34, and enters the heating unit 23. It is burned by the provided combustion type burner.
Next, the combustible combustible VOC gas exhaust gas is released into the atmosphere after harmful substances such as sulfur and chlorine are removed by a post-treatment process.
In the desorption / combustion mode, the valve 33 is automatically opened by the control unit 27 in accordance with a previously programmed sequence, and the inert gas is sent from the inert gas supply unit 26 into the second adsorption / desorption tower 22. Is entered.
Next, when the combustible VOC gas concentration in the adsorption section of the second adsorption / desorption tower 22 becomes equal to or lower than a predetermined concentration, the fuel supply valve 35 is closed, and the combustion type burner provided in the heating section 23 is stopped.
Next, after the burner is stopped, it is cooled by leaving it naturally or by sending it to the atmosphere. When the temperature in the second adsorption / desorption tower 22 becomes lower than 40 ° C., the mode is shifted to the adsorption mode.
[0027]
In the flammable volatile organic compound gas treatment method using the flammable volatile organic compound gas treatment system of this example, in the adsorption section of the first adsorption / desorption tower 21 and the adsorption section of the second adsorption / desorption tower 22. The flammable VOC gas concentration, the oxygen gas concentration and the temperature are detected by the detection units 36 and 37, and the results are monitored by the control unit 27 to control the opening and closing of each valve. This makes it possible to automatically shift to the subsequent processing steps in each processing step, and also to automatically shift from the “adsorption mode” to the “desorption / combustion mode”. Further, it is possible to easily confirm that the processing is completed in each processing step.
Further, by alternately performing the “adsorption mode” and the “desorption / combustion mode” in the first adsorption / desorption tower 21 and the second adsorption / desorption tower 22, the flammable VOC gas contained in the exhaust gas is constantly changed. Processing becomes possible, and combustible VOC gas can be efficiently processed.
[0028]
The flammable volatile organic compound gas processing system of the present invention has the same structure as the flammable volatile organic compound gas processing apparatus of the present invention. When more (three or more) adsorption / desorption towers 21 and second adsorption / desorption towers 22 are used in combination, the combustible VOC gas contained in the exhaust gas can be more efficiently processed.
[0029]
【The invention's effect】
As described above, according to the flammable volatile organic compound gas treatment apparatus of the present invention, since the adsorption section is heated by the combustion section from the most recent position, the energy efficiency can be greatly improved.
According to the flammable volatile organic compound gas processing system of the present invention, flammable VOC gas can always be processed.
According to the method for treating a flammable volatile organic compound gas of the present invention, the flammable VOC gas can be desorbed at a high temperature and a high concentration, and the desorption time can be reduced. As a result, the heating energy required for desorbing the combustible VOC gas can be minimized. In addition, the amount of replacement gas supplied for desorbing the combustible VOC gas can be greatly reduced. Furthermore, since the desorption temperature of the flammable VOC gas can be increased, it is possible to vaporize even the hardly volatile flammable VOC adsorbed on the adsorbent. As a result, the flammable VOC gas Since the amount of adsorption and the amount of desorption can be largely maintained, the amount of adsorbent used can be minimized. Then, by detecting the gas concentration in the adsorption section, a series of processing steps can be automated.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram schematically showing one example of a combustible volatile organic compound gas treatment apparatus of the present invention.
FIG. 2 is a schematic view showing a structure of a chamber constituting a combustible volatile organic compound gas treating apparatus of the present invention.
FIG. 3 is a diagram schematically illustrating an example of a combustible volatile organic compound gas treatment system according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gas introduction part, 2 ... Adsorption part, 3 ... Heat exchange part, 4 ... Combustion part, 4a ... Combustor, 5 ... Heating part, 6 ... Replacement gas Supply unit, 7: gas supply line, 8: on-off valve, 9: desorbed gas discharge unit, 10: exhaust gas discharge unit, 11: detection unit, 12: combustion gas discharge Unit, 13 post-processing unit, 14 fuel supply unit, 15 fuel supply line, 16 control unit, 17 chamber, 19 gas introduction line, 20 ... adsorbent, 21 ... first adsorption / desorption tower, 22 ... second adsorption / desorption tower, 23, 24 ... heating unit, 25 ... fuel supply unit, 26 ... Active gas supply unit, 27 ... control unit

Claims

A gas introduction unit for introducing the exhaust gas and the cooling gas into the adsorption unit, an adsorption unit for adsorbing the flammable volatile organic compound gas in the exhaust gas, and a replacement gas supply for supplying a replacement gas for replacing the oxygen gas in the adsorption unit And a heating unit for heating the adsorption unit and burning the combustible volatile organic compound gas desorbed from the adsorption unit; and a combustible volatile organic compound gas concentration and an oxygen gas concentration in the adsorption unit. A flammable volatile organic compound gas processing apparatus, comprising:

The heating unit includes a heat exchange unit that heats the adsorption unit and a combustion unit that burns the combustible volatile organic compound gas desorbed from the adsorption unit, and is integrated with the adsorption unit. The flammable volatile organic compound gas treatment apparatus according to claim 1, wherein:

A flammable volatile organic compound gas processing system comprising at least two flammable volatile organic compound gas processing apparatuses according to claim 1.

A method for treating a flammable volatile organic compound gas using the apparatus for treating a flammable volatile organic compound gas according to claim 1 or 2,
The adsorption process in which the combustible volatile organic compound gas in the exhaust gas introduced from the gas introduction unit is adsorbed and removed by the adsorption unit, and the atmosphere in the adsorption unit in which the combustible volatile organic compound gas is adsorbed have an oxygen gas concentration of A desorption preparation process in which the oxygen-deficient atmosphere is less than 8%, a desorption process in which the adsorbing section is heated in the oxygen-deficient atmosphere to desorb the flammable volatile organic compound gas, and a desorbed flammable volatile organic compound. A flammable fuel characterized by having a combustion process in which a compound gas is burned in an oxygen atmosphere having an oxygen gas concentration of 8% or more, and a cooling process in which an adsorbing section is cooled after the burning of the flammable volatile organic compound gas. Method for treating volatile organic compound gas.

5. The flammable volatilization method according to claim 4, wherein in the desorption preparation step, at least one of nitrogen gas, carbon dioxide gas and air from which oxygen has been removed is sent into the adsorption section to replace oxygen gas. Organic compound gas treatment method.

The method for treating a flammable volatile organic compound gas according to claim 4, wherein a temperature at which the adsorption section is heated is set to 100 to 800 ° C. in the desorption process.

7. The combustion process according to claim 4, wherein the flammable volatile organic compound gas desorbed from the adsorbing section is sent from the adsorbing section to the burning section and decomposed. 3. The method for treating a flammable volatile organic compound gas according to item 1.

In the combustion process, the flammable volatile organic compound is desorbed from the adsorbing section by using the volume expansion when the flammable volatile organic compound is desorbed and vaporized from the adsorbing section and the volumetric thermal expansion of the flammable volatile organic compound gas by heating as a thrust. The method for treating a flammable volatile organic compound gas according to claim 4, wherein the flammable volatile organic compound gas is sent from the adsorption section to the combustion section.

In the combustion process, the supply of the flammable volatile organic compound gas desorbed from the adsorption section to the combustion section from the adsorption section and the nitrogen gas, carbon dioxide gas, and oxygen were removed from the replacement gas supply section. Whether at least one of the air is intermittently fed into the adsorbing section during the combustion of the flammable volatile organic compound gas, or whether it is fed continuously and with a reduced or increased amount of air 9. The flammable volatile organic compound gas according to claim 4, wherein the flammable volatile organic compound gas is sent into the adsorption section immediately before the end of combustion of the flammable volatile organic compound gas. Processing method.

The method for treating a flammable volatile organic compound gas according to any one of claims 4 to 9,
Detecting the concentration of the flammable volatile organic compound gas in the adsorption section, controlling the transition from the adsorption step to the desorption preparation step, controlling the transition from the combustion step to the cooling step, Controlling the supply of the replacement gas in the step (a).

The method for treating a flammable volatile organic compound gas according to any one of claims 4 to 9,
A method for treating a flammable volatile organic compound gas, comprising detecting a concentration of oxygen gas in the adsorption section and controlling a transition from the desorption preparation step to the desorption step.

The method for treating a flammable volatile organic compound gas according to any one of claims 4 to 9,
Detecting a temperature of the adsorbing section and controlling a temperature of the adsorbing section when desorbing the combustible volatile organic compound gas from the adsorbing section. .