JP4095820B2 - Exhaust gas purification method and operation method of hardly decomposable halogen compound decomposition treatment facility - Google Patents

Description

【００１７】
【数８】

【００１８】
【数９】

【００１９】
〔式中、ＣＬＷ１は難分解性ハロゲン化合物の溶剤中の液中重量濃度（ｋｇ／ｋｇ）を表し、Ｍｗ１は難分解性ハロゲン化合物の分子量を表し、ＣＬＷ２は溶剤の液中重量濃度（ｋｇ／ｋｇ）を表し、Ｍｗ２は溶剤の分子量を表し、ＣＧＭ１は難分解性ハロゲン化合物の気中モル分圧（Ｐａ）を表し、ＶＰ１は所定温度における難分解性ハロゲン化合物の飽和蒸気圧（Ｐａ）を表し、ＣＬＭ１は難分解性ハロゲン化合物の液中モル濃度（ｍｏｌ／ｍｏｌ）を表し、ＣＧＷ１は排気ガス中に含まれる難分解性ハロゲン化合物の気中重量濃度（ｇ／ｍ^３Ｎ）を表す。〕から計算して求め、得られた計算結果から前記接触処理する条件を設定し、該設定条件下で前記排気ガスから難分解性ハロゲン化合物の除去を行なうことを特徴とする排気ガス浄化方法が提供される。
【００２０】
本発明の排気ガス浄化方法においては、前記得られた計算結果から、吸収液の使用量、接触温度又は吸収液の交換時期を設定し、該設定条件下で前記排気ガスから難分解性ハロゲン化合物の除去を行なうのが好ましく、前記吸収液として絶縁油を用いるのが好ましい。
【００２１】
また、本発明の排気ガス浄化方法は、前記接触処理を、吸収液と前記排気ガスとの接触処理を行なう気液向流型の吸収装置を使用して行なうものであるのが好ましく、前記排気ガスが、溶剤中で難分解性ハロゲン化合物の脱ハロゲン化反応を行なう反応設備から発生する難分解性ハロゲン化合物を含有する排気ガスの浄化方法であるのが好ましい。
【００２２】
本発明の第２によれば、難分解性ハロゲン化合物又は難分解性ハロゲン化合物の含有物の前処理を行なう前処理設備と、溶剤中で難分解性ハロゲン化合物の脱ハロゲン化反応を行なう分解反応設備と、前記脱ハロゲン化反応により生成した反応生成物の後処理を行なう後処理設備と、及び前記各設備から発生する排気ガスを浄化する排気ガス浄化設備とを有する難分解性ハロゲン化合物の分解処理施設の運転方法であって、前記排気ガス浄化設備が、吸収液と前記排気ガスとの接触処理を行なう吸収装置を有し、前記各設備から発生する難分解性ハロゲン化合物を含む排気ガスに含まれる難分解性ハロゲン化合物の気中重量濃度（ＣＧＷ１）を、下記式（１）〜（３）
【００２３】
【数１０】

【００２４】
【数１１】

【００２５】
【数１２】

【００２６】
〔式中、ＣＬＷ１は難分解性ハロゲン化合物の溶剤中の液中重量濃度（ｋｇ／ｋｇ）を表し、Ｍｗ１は難分解性ハロゲン化合物の分子量を表し、ＣＬＷ２は溶剤の液中重量濃度（ｋｇ／ｋｇ）を表し、Ｍｗ２は溶剤の分子量を表し、ＣＧＭ１は難分解性ハロゲン化合物の気中モル分圧（Ｐａ）を表し、ＶＰ１は所定温度における難分解性ハロゲン化合物の飽和蒸気圧（Ｐａ）を表し、ＣＬＭ１は難分解性ハロゲン化合物の液中モル濃度（ｍｏｌ／ｍｏｌ）を表し、ＣＧＷ１は排気ガス中に含まれる難分解性ハロゲン化合物の気中重量濃度（ｇ／ｍ^３Ｎ）を表す。〕から計算して求め、得られた計算結果から前記気液向流型の吸収装置の最適運転条件を選択して、該条件下で前吸収装置の運転を行なうものであることを特徴とする難ハロゲン化合物の分解処理施設の運転方法が提供される。
【００２７】
本発明の運転方法においては、前記計算結果から、前記吸収装置への前記排気ガスの供給量、供給圧力及び吸収液の交換時期を設定し、該設定条件下で前記吸収装置の運転するのが好ましい。
【００２８】
また、本発明の運転方法は、前記吸収装置として気液向流型の吸収装置を用いるのが好ましく、深冷コンデンサー及び活性炭充填塔をさらに有する排気ガス浄化設備を用いる運転方法であるのがより好ましい。
【００２９】
【発明の実施の形態】
以下、本発明の排気ガスの浄化方法及び難分解性ハロゲン化合物の分解処理施設の運転方法を詳細に説明する。
【００３０】
１）排気ガスの浄化方法方法
本発明の排気ガスの浄化方法は、難分解性ハロゲン化合物を含有する排気ガス、好ましくは溶剤中で難分解性ハロゲン化合物を脱ハロゲン化反応を行なう反応設備から発生する排気ガスを、吸収液と接触することにより難分解性ハロゲン化合物の除去を行なうものである。
【００３１】
本発明の対象とする難分解性ハロゲン化合物は、一般的に化学的に安定であり、自然環境中で容易に分解されないハロゲン化合物である。難分解性ハロゲン化合物としては、例えば、ＰＣＢ、ダイオキシン類、ポリ塩素化ベンゾフラン類、ポリ塩素化ベンゼン、ＤＤＴ等の芳香族ハロゲン化合物；ＢＨＣ等の脂環族ハロゲン化合物；等が挙げられる。
【００３２】
脱ハロゲン化反応に用いる溶剤としては、難分解性ハロゲン化合物の脱ハロゲン化反応に不活性なものであれば特に制限されない。例えば、ｎ−ヘキサン、ｎ−ヘプアン、ｎ−オクタン、ｎ−デカン、ケロシン、デカリン、流動パラフィン、電気絶縁油（例えば、ＪＩＳ Ｃ２３２０−１９９３に記載の電気絶縁油）、重油（例えば、ＪＩＳ Ｋ２２０５に記載の重油）等の炭化水素系溶剤；トルエン、キシレン等の芳香族炭化水素系溶剤；１，３−ジメチルイミダゾリン、スルホラン、ポリエチレングリコールジアルキルエーテル等の非プロトン性極性溶剤；等を用いることができる。これらの中でも、炭化水素類や芳香族炭化水素等の非極性有機溶剤の使用が好ましく、電気絶縁油（例えば、ＪＩＳ Ｃ２３２０−１９９３に記載の電気絶縁油）の使用が特に好ましい。
【００３３】
溶剤中で難分解性ハロゲン化合物を脱ハロゲン化反応を行なう方法としては特に制限はなく、種々の難分解性ハロゲン化合物の分解反応方法が使用できる。具体的には、▲１▼溶剤中、アルカリ金属分散体を用いて難分解性ハロゲン化合物の脱ハロゲン化反応を行なう方法、▲２▼溶剤中、難分解性ハロゲン化合物に水素供与体、添加剤及びアルカリを添加した後、窒素雰囲気下、常圧で加熱するアルカリ触媒分解法（ＢＣＤ法）、▲３▼難分解性ハロゲン化合物を、１，３−ジメチル−２−イミダゾリジノン、スルホラン、ポリエチレングリコールジアルキルエーテル等の非プロトン性極性溶媒中、水酸化ナトリウム、水酸化カリウム等のアルカリと反応させる化学抽出分解法、▲４▼難分解性ハロゲン化合物に、カリウム ターシャリーブトキシド等の有機アルカリ金属を添加し、加熱することより、脱ハロゲン化反応を行なう有機アルカリ金属法、▲５▼溶剤中、難分解性ハロゲン化合物をパラジウム／カーボン等の水素化触媒の存在下、水素ガス中、常圧で加熱する触媒水素化脱塩素化法（Ｐｄ／Ｃ法）等が例示される。
【００３４】
これらの中でも、難分解性ハロゲン化合物に由来する化合物の物質収支が明確であり、有害物質を副生せず、分解後の後処理が容易であること等の理由から、前記▲１▼のアルカリ金属分散体を使用する方法が好ましく、アルカリ金属分散体として金属ナトリウムを溶剤に分散させてなる金属ナトリウム分散体を用いる方法がより好ましい。
【００３５】
接触処理に用いる吸収液としては、難分解性ハロゲン化合物等に対して溶解力に優れるものが好ましい。その具体例としては、ｎ−ヘキサン、ｎ−ヘプアン、ｎ−オクタン、ｎ−デカン、ケロシン、デカリン、流動パラフィン、電気絶縁油（例えば、ＪＩＳ Ｃ２３２０−１９９３に記載の電気絶縁油）、重油（例えば、ＪＩＳ Ｋ２２０５に記載の重油）等の炭化水素類；トルエン、キシレン等の芳香族炭化水素；１，３−ジメチルイミダゾリン、スルホラン、ポリエチレングリコールジアルキルエーテル等の非プロトン性極性溶剤；等が挙げられる。
【００３６】
これらの中でも、難分解性ハロゲン化合物を吸収した吸収剤をそのまま脱ハロゲン化反応の溶剤として使用して、吸収した難分解性ハロゲン化合物を再度脱ハロゲン化反応に供することができることから、難分解性ハロゲン化合物の脱ハロゲン化反応を行なう際に用いられる溶剤がさらに好ましい。
【００３７】
前記接触処理は、排気ガスを吸収液と接触処理することができる吸収装置、例えば、図１に示す吸収装置を使用して行なうことができる。図１に示す吸収装置は、排気ガス２を吸収塔１の下部から送り込み、吸収液２を吸収塔１から送り込む気液向流型の吸収装置である。
【００３８】
吸収塔１の大きさは特に制限されず、浄化する排気ガスの流量等によって適宜所定の大きさのものを使用することができる。図１に示す吸収塔１では、内径が８０ｍｍ、高さが２２０ｍｍ程度であるが、塔の直径はガスの流量により種々の大きさのものを使用できる。
【００３９】
また、吸収塔１の中段部には充填物４が充填された充填部５が設けられており、該充填物の細かな隙間を吸収液３がゆっくりと流れる間に排気ガス２が吸収液３と十分に接触するようになっている。
【００４０】
充填物４としては、排気ガス２と吸収液３との接触が十分できるものであれば充填物４の種類に制限はない。例えば、スルーザーパッキング、スルーザーラボパッキングのような金網を組み上げることにより作成された規則性充填物や、ラシヒリング、ペルルサドルのような不規則性充填物等を用いることができる。
【００４１】
また、吸収液３の流れはダイアフラムポンプ６によって作り出され、その流量は流量計７によって制御されている。吸収液３の流れ良さを確保するためにヒーター（図示を省略）によって、吸収液３を２５〜３０℃に加熱して用いるのが好ましい。
【００４２】
本発明の浄化方法は、分解反応槽から発生する排気ガスに含まれる難分解性ハロゲン化合物の気中重量濃度（ＣＧＷ１）を、式（１）〜（３）から計算して求め、得られた計算結果から前記接触処理の条件を設定し、該設定条件下で前記排気ガスから難分解性ハロゲン化合物の除去を行なうことを特徴とする。
【００４３】
難分解性ハロゲン化合物の気中重量濃度（ＣＧＷ１、単位：ｇ／ｍ^３Ｎ）は、次のようにして求めることができる。以下の計算においては、溶剤及び難分解性ハロゲン化合物は供に非極性成分であり、難分解性ハロゲン化合物の濃度が希薄であるため、ラウールの法則に従う理想液体及び理想気体状態で取扱うことができる。すなわち、活量係数は１として取扱うことができる。
【００４４】
（ｉ）先ず、難分解性ハロゲン化合物の溶剤中の液中モル濃度（ＣＬＭ１、単位：ｍｏｌ／ｍｏｌ）を、
【００４５】
【数１３】

【００４６】
から求める。ここで、ＣＬＷ１は難分解性ハロゲン化合物の溶剤中の液中重量濃度（単位：ｋｇ／ｋｇ）を表し、Ｍｗ１は難分解性ハロゲン化合物の分子量を表し、ＣＬＷ２は溶剤の液中重量濃度（単位：ｋｇ／ｋｇ）を表し、Ｍｗ２は溶剤の分子量を表す。
(ii)次に、難分解性ハロゲン化合物の気中モル分圧（ＣＧＭ１、単位：Ｐａ）を、
【００４７】
【数１４】

【００４８】
から求める。ここで、ＶＰ１は所定温度（測定温度）における難分解性ハロゲン化合物の飽和蒸気圧（単位：Ｐａ）を表し、ＣＬＭ１は難分解性ハロゲン化合物の液中モル濃度（単位：ｍｏｌ／ｍｏｌ）を表す。飽和蒸気圧ＶＰ（単位：Ｐａ）と絶対温度Ｔ（単位：°Ｋ）との間には、下記関係式（４）が成り立つ。
【００４９】
【数１５】

【００５０】
ここで、ａ及びｂは、種々の絶対温度Ｔにおける蒸気圧を測定し、測定結果をプロットし、得られる検量線から求めることができる定数である。
【００５１】
(iii)次いで、難分解性ハロゲン化合物の気中重量濃度（ＣＧＷ１、単位：ｇ／ｍ^３／Ｎ）を、
【００５２】
【数１６】

【００５３】
から求める。ここで、１０１．３２５は、圧力の単位Ｐａ（パスカル）をａｔｍ（気圧）に換算する値である。
【００５４】
本発明においては、このようにして求められる難分解性ハロゲン化合物の気中重量濃度（ＣＧＷ１）が、理論的に予測される分解反応槽から発生する排気ガス、又は接触後の排気ガス中に含まれる難分解性ハロゲン化合物の理論的に予測される濃度とする（以下、「理論濃度」という。）。
【００５５】
そして、理論濃度の１〜１００倍、好ましくは５〜５０倍、より好ましくは５〜２０倍の濃度の難分解性ハロゲン化合物が排気ガス中に含まれていても、外部に放出される排気ガス中に含まれる難分解性ハロゲン化合物の濃度が規制値以下となるように、排気ガスと吸収液との接触処理の条件を設定する。
【００５６】
ここで、「接触処理の条件」には、吸収液の使用量、排気ガスを吸収液と接触させるときの排気ガスの単位時間あたりの供給量、吸収液を新しいものと交換する時期等の設定条件等が含まれる。
【００５７】
具体的には、前記理論濃度に基づいて吸収塔１の吸収液３の充填量及びその流量を定めることができる。例えば、吸収剤としてトランス油を使用する場合には、トランス油の使用量は全体で５〜１０リットルであり、その流速は通常５リットル／ｍｉｎ〜３０リットル／分と設定することができる。
【００５８】
また、前記理論濃度から定められる吸収液の交換時期（理論濃度から設定された難分解性ハロゲン化合物等の吸収量が飽和濃度に達したと考えられる時期）には、新しい吸収液と交換することとする。
【００５９】
図１に示す吸収装置では、吸収液３を閉鎖系で循環使用するものであるため、分解反応設備の運転を停止させた後、吸収液の交換を行なう。例えば、図１に示す吸収液３の循環流路のいずれかの場所にジョイントを結合して、そのジョイントを介して新しい吸収液を送り込みながら、一方の側から使用済の吸収液を抜き出すことにより、吸収液の交換を行なうことができる。この方法によれば、分解反応設備の運転を継続しながら、吸収液の交換が可能である。
【００６０】
なお、使用済の吸収液は、直接分解処理設備に移送して難分解性ハロゲン化合物の脱ハロゲン化反応に供してもよく、受入れ槽に移送して貯蔵し、一定量ずつをまとめて脱ハロゲン化反応に供することもできる。また、使用済の吸収液を貯蔵する槽を別個設置して、その槽に使用済の吸収剤を移送して貯蔵し、一定量ずつを脱ハロゲン化反応に供することもできる。
【００６１】
２）難分解性ハロゲン化合物の分解処理施設の運転方法
本発明の第２は、難分解性ハロゲン化合物又は難分解性ハロゲン化合物の含有物の前処理を行なう前処理設備と、溶剤中で難分解性ハロゲン化合物の脱ハロゲン化反応を行なう分解反応設備と、前記脱ハロゲン化反応により生成した反応生成物の後処理を行なう後処理設備と、及び前記分解反応設備から発生する排気ガスを浄化する排気ガス浄化設備とを有する難分解性ハロゲン化合物の分解処理施設の運転方法である。
【００６２】
本発明に用いる難分解性ハロゲン化合物の分解処理施設の概要を図２に示す。図２に示す難分解性ハロゲン化合物の分解処理施設は、難分解性ハロゲン化合物又は難分解性ハロゲン化合物含有物の前処理設備、難分解性ハロゲン化合物の脱ハロゲン化反応設備、後処理設備からなり、各設備には、各設備から発生する排気ガスを浄化する排気ガス浄化設備がさらに設置されている。
【００６３】
（１）前処理設備
前処理設備は、難分解性ハロゲン化合物又は難分解性ハロゲン化合物の含有物を受入れし、その種類に応じて分別を行なう設備である。
難分解性ハロゲン化合物の含有物は、その種類により難分解性ハロゲン化合物の濃度や部材の性状が異なる。例えば、変圧器等の電気機器の場合、メーカー、型番号等により構造や材質が異なり、それらに応じて以後の工程設計を行なう必要がある。
【００６４】
前処理設備に受入れられる難分解性ハロゲン化合物の含有物としては、難分解性ハロゲン化合物を含有する廃棄物が挙げられる。その具体例としては、難分解性ハロゲン化合物含有熱媒体、難分解性ハロゲン化合物含有電気絶縁体、難分解性ハロゲン化合物使用製品製造用の難分解性ハロゲン化合物、難分解性ハロゲン化合物混入汚染油、難分解性ハロゲン化合物使用機器洗浄剤廃液等の廃難分解性ハロゲン化合物及び難分解性ハロゲン化合物を含む廃油類；廃感圧紙、電気機器内の絶縁紙、清掃時のワイプ紙、電気機器内のスペーサー、漏電場所の建材、コンデンサ素子用ＰＰフィルム、シーラント材、使用済み保護具類、電線の被覆材、絶縁テープ類、難燃樹脂、電気機器内の絶縁物質、トランス・コンデンサ等の電気機器、電気機器容器、発熱交換器、コンデンサ素子用アルミ、電気機器内の各種留め金具、トランス巻線用銅線等の難分解性ハロゲン化合物含有の紙、木材、合成樹脂又は金属類；難分解性ハロゲン化合物を含有する難分解性ハロゲン化合物処理物；難分解性ハロゲン化合物入りコンデンサ；難分解性ハロゲン化合物入りトランス；等が挙げられる。
【００６５】
これらの中でも、難分解性ハロゲン化合物を多く含むものとして、難分解性ハロゲン化合物を含むケロシン、デカリン、電気絶縁油（ＪＩＳ Ｃ２３２０−１９９３に記載の電気絶縁油）、重油（ＪＩＳ Ｋ２２０５に記載の重油）、潤滑油及びこれらの混合物等が挙げられる。具体的には、難分解性ハロゲン化合物含有のトランス又はコンデンサー等である。
【００６６】
受入れした難分解性ハロゲン化合物の含有物の解体、切断、破断、分別等を行ない、これらの解体、切断、破断し、分別した物から難分解性ハロゲン化合物を回収するための洗浄が行なわれる。
【００６７】
洗浄方法としては、浸漬法、液循環法、超音波法、バブリング法などが挙げられる。用いられる洗浄剤としては、洗浄力が優れ、火災、爆発の危険性が少なく、毒性が低く、洗浄後の乾燥が容易であること等が必要である。洗浄により回収された難分解性ハロゲン化合物は、洗浄剤とともに保管容器に保管され、必要に応じて洗浄剤との分離を行なって、次の脱ハロゲン化反応工程に送られる。
【００６８】
また、難分解性ハロゲン化合物を含有するトランス又はコンデンサーの場合には、難分解性ハロゲン化合物の含有物は密閉容器に封入されている。そのため、上記した洗浄等による回収法は作業効率上好ましくない。そこで、この場合には、トランス又はコンデンサーから難分解性ハロゲン化合物を抜き出す作業を行なうのが好ましい。
【００６９】
例えば、ＰＣＢ含有のトランス（又はコンデンサー）の場合には、トランス（又はコンデンサー）を固定し、該トランス（又はコンデンサー）の所定の位置にドリル等で穴を明け、該穴を真空ラインに連結し、トランス（又はコンデンサー）内を加圧しながらから該穴から難分解性ハロゲン化合物を吸引することにより、難分解性ハロゲン化合物を取り出すことができる。
【００７０】
また、上記のようにして難分解性ハロゲン化合物を取り出したトランス又はコンデンサ内部には、繊維等に染み込んだ難分解性ハロゲン化合物が残存している場合がある。この場合には、例えば、内部を洗浄剤により洗浄したり、難分解性ハロゲン化合物又は難分解性ハロゲン化合物を含有する部材を真空加熱炉に入れ、該真空加熱炉内を０．０１〜５０ｍｂａｒに減圧にし、減圧を継続しながら前記部材を２５０〜６５０℃に加熱して、前記部材を炭化させるとともに難分解性ハロゲン化合物又は難分解性ハロゲン化合物を含有する絶縁油を蒸発させ、前記真空加熱炉からの排気系上で凝縮することにより、難分解性ハロゲン化合物又は難分解性ハロゲン化合物を含有する絶縁油を回収することができる。
【００７１】
また、以上の前処理工程は、難分解性ハロゲン化合物の再汚染を防止するために、密閉された空間内において行ない、該空間から発生する排気ガスは、排気ガス浄化設備により浄化した後に屋外に排出するようにするのが好ましい。浄化方法としては、例えば、活性炭を吸着した活性炭充填塔内を用いる方法や、前記図２に示した排気ガス浄化設備を用いる方法等が挙げられる。排気ガス浄化設備で回収された難分解性ハロゲン化合物は、次の脱ハロゲン化工程へ送られる。
【００７２】
（２）分解反応設備
分解反応設備は、一般的には、難分解性ハロゲン化合物及び薬剤（アルカリ）を、所望により活性剤及び溶媒等とともに反応槽に入れ、所定温度で、所定時間、撹拌装置を用いて反応槽内を撹拌することにより、難分解性ハロゲン化合物の脱ハロゲン化反応を行う設備である。
【００７３】
分解反応設備としては特に制限はなく、種々の難分解性ハロゲン化合物の分解反応方法に適用できるものが挙げられる。具体的には、上述の排気ガスの浄化方法の項で例示した脱ハロゲン化反応を行なうことができる設備が挙げられる。これらの中でも、難分解性ハロゲン化合物に由来する化合物の物質収支が明確であり、有害物質を副生せず、分解後の後処理が容易であること等の理由から、アルカリ金属分散体法を使用する分解反応設備が好ましく、アルカリ金属分散体として金属ナトリウム分散体を用いる分解処理設備が特に好ましい。
【００７４】
分解処理設備は、通常、撹拌装置付きの反応槽、反応温度制御装置等からなる。撹拌装置は、少なくとも撹拌翼と撹拌モータからなり、撹拌翼の回転速度を自由に調節でき、難分解性ハロゲン化合物と必要な薬剤、触媒、溶剤等を十分に撹拌でき、所定の分解反応を安定的かつ均一に行わせる撹拌装置を用いるのが好ましい。温度制御装置は、反応槽内の温度（分解反応の温度）を所定温度に調節する装置であり、難分解性ハロゲン化合物の濃度に応じて定められた分解反応設備の運転管理基準に従って、反応前から反応終了までを通じて、温度、圧力等が基準の範囲内で適切かつ安全な運転が確保されるように制御する機能を有するのが好ましい。
【００７５】
また、上記したいずれの脱ハロゲン化反応方法による場合にも、脱ハロゲン化反応を安全に行なうために、脱ハロゲン化反応は窒素ガスやアルゴンガス等の不活性ガス雰囲気下で行うのが好ましい。
前記分解反応設備において脱ハロゲン化反応を行なって得られる反応生成物は後処理設備に送られる。
【００７６】
（３）後処理設備
後処理設備は、反応生成物中に含まれる難分解性ハロゲン化合物の分解物、未反応の薬剤、活性化剤、溶剤等を分離し、回収を行なって、最終的に廃棄又は再利用可能な状態にする設備である。
【００７７】
後処理設備としては、具体的には、遠心分離機、ろ過装置、中和洗浄装置、分液装置、蒸留装置等が挙げられる。そして、これらの装置を用いて、反応生成物から固形分の分離及び回収、過剰のアルカリ分の分解、溶媒の回収、生成塩の分離、触媒の分離等の作業が行なわれる。
【００７８】
例えば、高濃度の難分解性ハロゲン化合物含有物をアルカリ金属分散体を用いて脱ハロゲン化反応した反応生成物には、絶縁油等の溶媒及び固形物（ポリフェニレン型重合体、絶縁油、水酸化ナトリウム、食塩、水分等を含む。）が含まれる。後処理設備では、固液分離する遠心分離機、洗浄装置、分液装置等からなり、これらの装置を使用して、油分と固形物を分離する作業が行なわれる。
【００７９】
また、低濃度の難分解性ハロゲン化合物の含有物を脱ハロゲン化反応させた場合には、反応生成物に水を加えることにより、ビフェニル類、食塩水及び絶縁油の混合物が得られる。次いで、前記混合物を洗浄し静置した後、油分、タール分及び排水に分液装置を用いて分液し、排水を蒸発装置により水分を蒸発させ、得られた固形分を回収し、蒸発した水分を水分回収装置によりプロセス水として回収する作業が行なわれる。
【００８０】
この場合、水洗に用いられたアルカリ性洗浄液から水分及びアルカリ成分を回収し、このものを、再度を前記難分解性ハロゲン化合物の分解物の洗浄液として再利用することができる。また、低濃度の難分解性ハロゲン化合物含有物をアルカリ金属分散体を用いて分解処理する場合にはアルカリ金属分散体及び溶媒のほかに活性化剤を添加するが、この活性剤として、前記難分解性ハロゲン化合物の分解物の洗浄に使用した水溶液を用いることもできる。
【００８１】
このようにすることで、大規模な排水設備を用いることなく短工程で分解後の後処理を行なうことができ、反応生成物に用いられる高極性成分を洗浄除去することができ、かつ、アルカリ性洗浄液を濃縮濃度を調整することで、アルカリ成分を裁量することができる。
【００８２】
また、本発明の難分解性ハロゲン化合物の分解処理施設においては、図示を省略しているが、難分解性ハロゲン化合物の分解反応が完了し、難分解性ハロゲン化合物の含有量が一定の基準値以下に達したのを確認するための測定設備がさらに設置されるのが好ましい。
【００８３】
かかる測定設備としては、例えば、ＥＣＤ−ＧＣ（エレクトロンキャプチャー検出器付きガスクロマトグラフィー）、ＧＣ−ＭＳ（ガスクロマト−マススペクトル測定装置）等の難分解性ハロゲン化合物の含有量を測定する装置や、反応開始から所定時間経過した時点で、反応混合物の一部を抜き取り（サンプリング）、このものを精製して、上記測定装置により測定可能状態にするためのシリカゲルカラム等の分離・精製装置が挙げられる。
【００８４】
（４）排気ガスの浄化設備
排気ガス浄化設備は、分解反応設備、前処理設備及び／又は後処理設備から排出される排気ガスを浄化の対象とする設備であるが、分解反応設備から排出される排気ガスを浄化の対象とするのが特に好ましい。
【００８５】
本発明に好適な排気ガス浄化設備としては、例えば、図３に示す排気ガス浄化設備が挙げられる。図３に示す排気ガス浄化設備は、吸収液が充填された気液向流型の吸収装置１１、深冷コンデンサー１２、ミストセパレーター１３、活性炭が充填された活性炭充填塔１４及び逆火防止器１５とからなる。なお、排気ガスに含まれる難分解性ハロゲン化合物の含有量が低い場合には、吸収装置１１の設置を省略することができる。
【００８６】
本発明においては、前記反応設備から発生する排気ガスに含まれる難分解性ハロゲン化合物の気中重量濃度（ＣＧＷ１）を、前記式（１）〜（３）から計算して求め、得られた計算結果から前記気液向流型の吸収装置１１の最適運転条件を選択して行なう。
【００８７】
ここで、前記気液向流型の吸収装置１１の最適運転条件とは、排気ガスに含まれる難分解性ハロゲン化合物が、最も効率よく（即ち、製造コスト及び運転コスト面から見て最も有利に）、かつ、外部に放出される浄化処理済の排気ガスに含まれる難分解性ハロゲン化合物が規制値以下になるような運転条件で、気液向流型の吸収装置を有する排気ガス浄化設備の運転を行なうという意味である。具体的には、前記計算結果から、前記吸収装置への前記排気ガスの供給量、供給圧力及び吸収液の交換時期等を設定し、該設定条件下で運転を行なう。
【００８８】
図３に示す排気ガス浄化装置においては、具体的には次のようにして排気ガスの浄化を行なうことができる。
（ａ）分解反応槽８から発生した排気ガスは、先ず、ベントコンデンサー９により冷却され、溶媒蒸気が液化（凝縮）して、反応槽８に戻される。
（ｂ）次いで、シールトラップ１０を通過して、吸収装置１１へ送られる。シールトラップ１０は、排気ガスの逆流を防止するために設置される。
（ｃ）吸収装置１１に送り込まれた排気ガスは吸収液と接触して、排気ガスに含まれる難分解性ハロゲン化合物等が吸収除去される。このときの接触の条件の選択は、前述の排気ガスの浄化方法の項で説明した方法と同様にして行なうことができる。
【００８９】
（ｄ）吸収工程を経た排気ガスは冷却工程に送られる。冷却工程では、排気ガスを深冷コンデンサー１２により０℃以下、好ましくは−１０℃以下に急冷して、排気ガスに含まれる気体成分を液化（凝縮）させる。吸収剤と接触させた排気ガスを深冷コンデンサー１２を使用して冷却することにより、微量の難分解性ハロゲン化合物等を凝縮・除去することができる。深冷コンデンサー１２としては特に制限されず、公知のものを使用することができる。
【００９０】
即ち、吸収工程を経た排気ガスの温度は、通常２０〜３０℃に温められているが、深冷コンデンサー１２を通過させることによって、０℃以下、好ましくは−１０℃以下に冷却されて、排気ガス中の殆どのガス成分が液化し、凝縮する。凝縮した液体は凝縮器（図示を省略）により捕集される。凝縮器に捕集された難分解性ハロゲン化合物等は分解反応設備へ送られ、脱ハロゲン化反応に供せられる。
【００９１】
（ｅ）次に、深冷コンデンサー１２を通過した排気ガスはミストセパレーター１３に送られる。ミストセパレーター１３は、ミスト状物（液滴状物）を気体から除去するための分離装置である。深冷コンデンサー１２により冷却された排気ガスをミストセパレーター１３を通過させることにより、深冷コンデンサー１２の凝縮器に回収されなかった微粒子状のミスト状物（溶剤及び難分解性ハロゲン化合物成分）を気体成分から完全に分離することができる。ミストセパレーター１３の設置は省略することができるが、難分解性ハロゲン化合物等を完全に除去する観点から設置するのが好ましい。
【００９２】
（ｆ）次いで、ミストセパレーター１３を通過した排気ガスを活性炭が充填された活性炭充填塔１４内を通過させることにより、活性炭による吸着処理を行なう。排気ガスを活性炭と接触さする温度は、通常０℃〜３０℃である。また、活性炭の使用量は特に制限されず、排気ガスの流量等に応じて適宜設定することができる。活性炭充填塔１４に充填する活性炭としては特に制限はなく、ヤシ殻系、木質系、石炭系のいずれも用いることができるし、粒状炭や破砕炭を粉砕して使用することもできる。
【００９３】
（ｇ）最後に、以上のようにして浄化された排気ガスは、逆火防止器１５を経て外部に放出される。逆火防止器１５は、外部からの火気の進入を防止するために設置される。本発明の浄化方法は、特に難分解性ハロゲン化合物の脱ハロゲン化反応を行なう分解反応槽から発生する排気ガスを浄化の対象とする。従って、水素ガス等の可燃性ガスも排気ガスに含まれる為、逆火防止器を安全のために設置するのが好ましい。
以上のようにして難分解性ハロゲン化合物等を含有する排気ガスを安全に浄化することができる。
【００９４】
【実施例】
実施例１
前記図３に示す難分解性ハロゲン化合物の分解処理施設を使用してＰＣＢ含有のトランス油の無害化処理を行なった。
先ず、前処理設備にて、廃棄されたトランスから抜油してＫＣ−３００（ＰＣＢの１種、分子量：３３４）４８ｍｇ／ｋｇ、ＴＣＢ（トリクロロベンゼン）１１ｍｇ／ｋｇ、水５４ｍｇ／ｋｇ含有のトランス油（分子量：２６０）を４４００ｋｇを得た。
【００９５】
次に、排気ガス処理系を設計するために、絶対温度Ｔ（単位：°Ｋ）におけるトランス油及びＰＣＢ（ＫＣ−３００、分子量：２６４）の飽和蒸気圧（ＶＰ、単位：Ｐａ）を測定した。そして、得られたデータを横軸に１／Ｔ（°Ｋ）、縦軸にＬｏｇ（ＶＰ）として、検量線を作成し、次式（５）及び（６）を得た。以下の式において、ＶＰ２はＫＣ−３００の飽和蒸気圧を表し、ＶＰ３はトランス油の飽和蒸気圧を表し、Ｔ１及びＴ２は絶対温度（°Ｋ）を表す。
【００９６】
【数１７】

【００９７】
【数１８】

【００９８】
式（５）から得られる反応温度（Ｔ’）におけるＶＰ２を求め，これを、式（７）、（８）及び（９）
【００９９】
【数１９】

【０１００】
【数２０】

【０１０１】
【数２１】

【０１０２】
（式中、ＣＬＭ２はＫＣ−３００の液中モル濃度を表し、ＣＬＷ２はＫＣ−３００の液中重量濃度を表し、ＣＬＷ３はトランス油の液中重量濃度を表し、ＣＧＭ２はＫＣ−３００の気中モル分圧（Ｐａ）を表す。）から、ＫＣ−３００の気中重量濃度（ＣＧＷ２、単位：ｇ／ｍ^３Ｎ）を得た。計算結果は、２６６，６６７〜３８６，６６７ｎｇ／ｍ^３であった。
【０１０３】
これを理論濃度として、これの１５倍の濃度のＫＣ−３００が排気ガスに含まれるとして（４，０００，０００〜５，８００，０００ｎｇ／ｍ^３）、排気ガスの吸収液による接触処理を行なうこととした。
【０１０４】
次に、吸収装置の運転条件を設定するために、排気ガスの空塔質量速度（Ｇ）及び吸収液の空塔質量速度（Ｌ）とホールディングとの関係を調べた。実験結果を図４に示す。図４からわかるように、吸収液（トランス油）の空塔質量速度（Ｌ）が１，３００〜４５００ｋｇ／ｍ^２・ｈｒの範囲内で一定であれば、Ｇの値が３０〜３００ｋｇ／ｍ^２・ｈｒの範囲において、ホールドアップは起こさないことがわかった。
【０１０５】
そこで、液の空塔質量速度（Ｌ）を２，４００ｋｇ／ｍ^２・ｈｒ、ガスの空塔質量速度（Ｇ）を２５０ｋｇ／ｍ^２・ｈｒと設定し、実際に接触処理試験を行い、吸収液中のＫＣ−３００の濃度と出口濃度／理論濃度（比率）との関係を調べた。接触の温度は３４．２〜３５．６℃である。結果を図５に示す。図５中、横軸は吸収液中のＫＣ−３００の濃度（ｍｇ／ｋｇ）を、縦軸は、吸収装置の出口でのＫＣ−３００の実際の測定濃度（出口濃度）／吸収装置から発生するＫＣ−３００の理論濃度（理論濃度）を表す。
【０１０６】
図５からわかるように、実測された吸収装置出口の排気ガス中のＫＣ−３００の濃度は、５００〜１，３００ｎｇ／ｍ^３Ｎであり、吸収液（トランス油）中のＫＣ−３００の濃度約２〜６ｍｇ／ｋｇの範囲において、理論濃度の１５分の１以下であり、吸収率は９９．９％以上であった。
また、以上のことから、吸収装置出口のＫＣ−３００の濃度が１，３００ｎｇ／ｍ^３Ｎを超える場合には、吸収液を新しいものと交換する必要があると判断することとした。
【０１０７】
次いで、上記で得られたＰＣＢ含有のトランス油４４００ｋｇを分解反応槽に入れ、内部を窒素置換した後、内温が６０℃になるまで加熱した。そこへ、金属ナトリウム分散体（金属ナトリウム１１ｋｇを含む。）６５ｋｇを入れ、水を４．３１ｋｇ添加して、６０〜７０℃で２時間撹拌して脱ハロゲン化反応を行なった。
【０１０８】
同時に、分解反応槽から発生した排気ガスを、図３に示す反応排気ガス浄化設備に送り込み、上記で設定した運転条件で排気ガスの浄化を行なった。
【０１０９】
下記Ａ〜Ｅポイントにおける排気ガスの分析結果を第１表に示す。
Ａポイント：シールトラップ１０
Ｂポイント：吸収装置１１の出口
Ｃポイント：深冷コンデンサー１２の出口
Ｄポイント：ミストセパレータ１３の出口
Ｅポイント：活性炭充填塔１４の出口
【０１１０】
排気ガスの分析は、図６に示す排気ガスサンプリング装置にて測定用サンプルを得た後、高分解能ガスクロマトグラフ質量分析計（ＧＣ−ＭＳ）を使用して行なった。即ち、前記Ａ〜Ｅの各サンプリング口から排気ガスを第１表に示す量（採取量）を採集し、蒸留水２５０ｍｌ（内容積５００ｍｌのガス吸収瓶に入れたもの）中を氷冷下に通過させ、さらにＸＡＤ−２−樹脂（スチレン系樹脂吸着剤）チューブ及びジエチレングリコール（２５０ｍｌ）中を氷冷下に通して難分解性ハロゲン化合物以外の不純物を除去して測定用サンプルを得、このものを高分解能ＧＣ−ＭＳを使用して分析した。
【０１１１】
また、第１表中、略号は次の意味で用いている。
Ｍｏｎｏ−ＣＢｓ：モノクロロビフェニール
Ｄｉ−ＣＢｓ：ジクロロビフェニール
Ｔｒｉ−ＣＢｓ：トリクロロビフェニール
Ｔｅｔｒａ−ＣＢｓ：テトラクロロビフェニール
Ｐｅｎｔａ−ＣＢｓ：ペンタクロロビフェニール
Ｈｅｘａ−ＣＢｓ：ヘキサクロロビフェニール
Ｈｅｐｔａ−ＣＢｓ：ヘプタクロロビフェニール
Ｏｃｔａ−ＣＢｓ：オクタクロロビフェニール
Ｎｏｎａ−ＣＢｓ：ノナクロロビフェニール
Ｄｅｃａ−ＣＢｓ：デカクロロビフェニール
Ｔｏｔａｌ−ＰＣＢｓ：上記Ｍｏｎｏ−ＣＢｓ〜Ｄｅｃａ−ＣＢｓの合計量
【０１１２】
【表１】

【０１１３】
第１表から、活性炭充填塔出口から排出される排気ガスからはほとんど難分解性ハロゲン化合物が検出されず、排気ガスの浄化がほぼ完全に行なわれたことを示している。
【０１１４】
次いで、得られた反応液を後処理設備に設置された加熱可能な分液装置に移送した。反応液を攪拌しながら、水を１０．９３ｋｇを６０〜７０℃で１時間かけて滴下した。水の滴下終了後、さらに同温度で３０分攪拌して過剰の金属ナトリウム分散体を完全に分解させた。その後、反応槽の温度を８０℃まで昇温させながら、アルカリ水４７９．９ｋｇ（水酸化ナトリウム０．３ｋｇ含有）を添加し、３０分間撹拌した。８０℃前後で１４．５時間静置して、処理油層と水層とに分液し、水層を分取した。分取した水層は蒸発回収した。回収量は、４７４．４ｋｇであった。
【０１１５】
水層を除いた処理油層に水２５．６ｋｇ及び前記蒸発回収した水４７４．４ｋｇを添加して、８０℃で１時間攪拌し、８０℃で５時間静置して、処理油層と水層とに分液し、水層を分取し、処理油層を得た。この水層は、これに水酸化ナトリウムを添加して所定のアルカリ濃度になるように濃度調整を行なうことにより、反応液の洗浄用のアルカリ水として再利用することができる。
【０１１６】
以上のようにして得られた処理油層は全体で４４６５．１７ｋｇであり、トランス油４４４０ｋｇ、水２５．０２ｋｇ、水酸化ナトリウム０．０２ｋｇ、ビフェニル０．１ｋｇ及びベンゼン０．０２ｋｇがそれぞれ含まれていた。
また、この排気ガス浄化設備の活性炭充填塔出口から排出される排気ガスは、ほとんどポリ塩化ビフェニル類は検出されなかった。
【０１１７】
【発明の効果】
本発明によれば、難分解性ハロゲン化合物を含有する排気ガスを完全、かつ効率よく浄化する排気ガス浄化方法、及び難分解性ハロゲン化合物の分解処理施設の運転方法が提供される。
【図面の簡単な説明】
【図１】 図１は、本発明の排気ガス浄化方法を実施するための気液向流型の吸収装置の概念図である。
【図２】 図２は、本発明の難分解性ハロゲン化合物の分解処理施設の運転方法に好適な難分解性ハロゲン化合物の分解処理施設の概念図である。
【図３】 図３は、図２に示す難分解性ハロゲン化合物の分解処理施設の排気ガス浄化設備の概要図である。
【図４】 図４は、排気ガスを図１に示す吸収装置に供給する場合における排気ガスの空塔質量速度（Ｇ）とホールドアップ（ｈ）との関係を表す図である。
【図５】 図５は、吸収液中のＰＣＢ（ＫＣ−３００）の濃度と吸収装置の出口におけるＰＣＢ（ＫＣ−３００）の実測濃度（出口濃度）／理論濃度との関係を表す図である。
【図６】 図６は、排気ガスを分析するための測定サンプルを得るための装置を表す図である。
【符号の説明】
１…吸収塔、２…排気ガス、３…吸収液、４…充填物、５…充填部、６…ダイアフラムポンプ、７…流量計、８…分解反応槽、９…ベントコンデンサー、１０…シールトラップ、１１…吸収装置、１２…深冷コンデンサー、１３…ミストセパレーター、１４…活性炭充填塔、１５…逆火防止器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for efficiently purifying exhaust gas containing a hardly decomposable halide such as polychlorinated biphenyl (PCB), and a method for operating a decomposition treatment facility for a hardly decomposable halogen compound.
[0002]
[Prior art]
A hardly decomposable halogen compound such as PCB is generally chemically stable and is not easily decomposed in a natural environment (this halogen compound is referred to as a “hardly decomposable halogen compound”). In addition, they are taken into animals and plants, accumulate and concentrate, and have an adverse effect. Therefore, promotion of the detoxification treatment of these hardly decomposable halogen compounds is an important issue.
[0003]
The detoxification treatment of a non-degradable halogen compound or the like is usually performed by pre-treatment equipment for pre-treatment of a hardly-decomposable halogen compound or a substance containing the hardly-decomposable halogen compound, and a decomposition reaction facility for dehalogenating the hardly-degradable halogen compound And a decomposition treatment facility for a hardly decomposable halogen compound having a post-treatment facility for performing a post-treatment of the reaction mixture.
[0004]
In addition, from the decomposing equipment that performs dehalogenation reaction of hardly decomposable halogen compounds, environmental pollutants such as reaction product gas or evaporated hardly decomposed halogen compounds (hereinafter referred to as “hardly decomposable halogen compounds”). Exhaust gas is generated. When exhaust gas containing environmental pollutants is discharged to the outside as it is, the natural environment will be recontaminated, so it is necessary to remove hardly decomposable halogen compounds, etc. from this exhaust gas. "). In particular, a hardly decomposable halogen compound is a regulated substance, and it is necessary to completely purify the exhaust gas so as not to leak to the outside even in a trace amount.
[0005]
Conventionally, as a method of purifying the exhaust gas, an activated carbon packed tower packed with activated carbon is connected to a decomposition reaction facility and installed, and the exhaust gas is passed through the activated carbon packed tower, thereby causing a hardly decomposable halogen compound or the like. Is known (see above, “PCB Processing Technology Guidebook”, etc.).
[0006]
[Problems to be solved by the invention]
However, in this method of adsorption removal using activated carbon, it has been complicated and difficult to efficiently and completely remove the hardly decomposable halogen compound generated from the decomposition reaction facility.
[0007]
Therefore, the present inventors have adopted a method of treating exhaust gas containing a hardly decomposable halogen compound with an absorbing solution having excellent solubility of the hardly decomposable halogen compound as a method for purifying the exhaust gas. This method uses an absorption device having a circulation path for circulating the absorption liquid and a packing installed in the circulation path. The absorption liquid is allowed to flow down from the top of the packing, and at the same time, exhaust gas is discharged from the packing. It is sent from the lower part and discharged from the upper part, and the hardly decomposable halogen compound contained in the exhaust gas is absorbed by the absorption liquid (this type of absorption device is called “gas-liquid countercurrent type absorption device”). ).
[0008]
However, this method has the following problems to be solved.
In a gas-liquid countercurrent type absorption device, a certain amount of absorption liquid exists in the device according to the flow rate of the absorption liquid to be circulated (this is referred to as “hold-up”). When the liquid flow rate is kept constant and the exhaust gas supply rate is increased, the hold-up is substantially constant, and the gas passage pressure loss increases in proportion to the power of the gas flow rate.
[0009]
However, when the gas flow rate exceeds a certain value determined by the apparatus conditions, the hold-up increases and the gas pressure loss increases rapidly. Further, when the gas flow rate is increased, the absorption liquid cannot flow down and flows backward toward the top of the column (this is called “loading”). Therefore, it is necessary to operate the absorption device under conditions that do not cause loading and can make contact with the hardly decomposable halogen compound as efficiently as possible.
[0010]
In addition, when the amount of the hard-to-decompose halogen compound absorbed in the absorbing solution is saturated, it is necessary to replace the absorbing solution with a new one. Conventionally, in order to know the replacement time, the absorbing solution is sampled at regular intervals. For example, the content of the hardly decomposable halogen compound is measured. However, every time sampling is performed, the operation of the decomposition reaction tank must be stopped, and the analysis operation is complicated.
[0011]
Therefore, in the case where purification treatment of exhaust gas containing a hardly decomposable halogen compound is actually performed using the above-mentioned absorption device, the conditions under which it is possible to completely remove the hardly decomposable halogen compound completely and efficiently. The problem was whether to operate the absorber.
[0012]
The present invention has been made in view of such a situation, and an exhaust gas purification method for efficiently and completely purifying exhaust gas containing a hardly decomposable halogen compound, and a decomposition treatment facility for the hardly decomposed halogen compound. It is an object to provide a driving method.
[0013]
[Means for Solving the Problems]
The present inventors diligently studied a method for efficiently removing a hardly decomposable halogen compound contained in exhaust gas by using a gas-liquid countercurrent type absorption device.
As a result, based on the theoretical formula for calculating the component concentration in the gas in the presence of gas and liquid, the content of the solvent or absorption liquid used in the dehalogenation reaction and the hardly decomposable halogen compound in the liquid state, and the solvent From the value of the vapor pressure of the hardly decomposable halogen compound, a calculation formula for calculating the weight concentration of the hardly decomposable halogen compound contained in the exhaust gas was derived.
[0014]
And content of the hardly decomposable halogen compound (gaseous state) contained in exhaust gas was computed using the obtained formula. Furthermore, from the calculation results obtained, by setting the optimum conditions for bringing the exhaust gas into contact with the absorbent, it is possible to completely and extremely efficiently remove the hardly decomposable halogen compound contained in the exhaust gas. The present inventors have found that the present invention can be accomplished and have completed the present invention.
[0015]
Thus, according to the first aspect of the present invention, there is provided an exhaust gas purification method for removing a hardly decomposable halogen compound from the exhaust gas by subjecting the exhaust gas containing the hardly decomposable halogen compound to contact with an absorbing solution. ,
The air weight concentration (CGW1) of the hardly decomposable halogen compound contained in the exhaust gas is expressed by the formulas (1) to (3).
[0016]
[Expression 7]

[0017]
[Equation 8]

[0018]
[Equation 9]

[0019]
[Wherein, CLW1 represents the weight concentration (kg / kg) of the hardly decomposable halogen compound in the solvent, Mw1 represents the molecular weight of the hardly decomposable halogen compound, and CLW2 represents the weight concentration of the solvent in the solution (kg / kg). kg), Mw2 represents the molecular weight of the solvent, CGM1 represents the atmospheric partial pressure (Pa) of the hardly decomposable halogen compound, and VP1 represents the hardly decomposable halogen compound at a predetermined temperature.Saturated vapor pressure(Pa), CLM1 represents the molar concentration (mol / mol) of the hardly decomposable halogen compound in the liquid, and CGW1 represents the weight concentration in air (g / m) of the hardly decomposable halogen compound contained in the exhaust gas.³N). The exhaust gas purification method is characterized in that the contact treatment condition is set from the obtained calculation result, and the hardly decomposable halogen compound is removed from the exhaust gas under the set condition. Provided.
[0020]
In the exhaust gas purification method of the present invention, based on the obtained calculation results, the use amount of the absorbing liquid, the contact temperature or the replacement timing of the absorbing liquid is set, and the hardly decomposed halogen compound from the exhaust gas under the set conditions Is preferably removed, and insulating oil is preferably used as the absorbing liquid.
[0021]
In the exhaust gas purification method of the present invention, the contact treatment is preferably performed using a gas-liquid countercurrent type absorption device that performs contact treatment between an absorbing liquid and the exhaust gas. Preferably, the gas is a method for purifying exhaust gas containing a hardly decomposable halogen compound generated from a reaction facility that performs a dehalogenation reaction of the hardly decomposable halogen compound in a solvent.
[0022]
According to the second aspect of the present invention, a pretreatment facility for pretreating a hardly decomposable halogen compound or a material containing a hardly decomposable halogen compound, and a decomposition reaction for dehalogenating the hardly decomposable halogen compound in a solvent Decomposition of a hardly decomposable halogen compound having equipment, post-treatment equipment for post-treatment of the reaction product generated by the dehalogenation reaction, and exhaust gas purification equipment for purifying exhaust gas generated from each equipment An operation method of a treatment facility, wherein the exhaust gas purification equipment includes an absorption device that performs contact treatment between an absorbing liquid and the exhaust gas, and the exhaust gas containing the hardly decomposable halogen compound generated from each equipment The air weight concentration (CGW1) of the hardly decomposable halogen compound contained is expressed by the following formulas (1) to (3).
[0023]
[Expression 10]

[0024]
## EQU11 ##

[0025]
[Expression 12]

[0026]
[Wherein, CLW1 represents the weight concentration (kg / kg) of the hardly decomposable halogen compound in the solvent, Mw1 represents the molecular weight of the hardly decomposable halogen compound, and CLW2 represents the weight concentration of the solvent in the solution (kg / kg). kg), Mw2 represents the molecular weight of the solvent, CGM1 represents the atmospheric partial pressure (Pa) of the hardly decomposable halogen compound, and VP1 represents the hardly decomposable halogen compound at a predetermined temperature.Saturated vapor pressure(Pa), CLM1 represents the molar concentration (mol / mol) of the hardly decomposable halogen compound in the liquid, and CGW1 represents the weight concentration in air (g / m) of the hardly decomposable halogen compound contained in the exhaust gas.³N). The optimum operating conditions of the gas-liquid countercurrent type absorber are selected from the obtained calculation results, and the preabsorber is operated under the conditions. A method of operating a facility for decomposing a halogenated compound is provided.
[0027]
In the operation method of the present invention, from the calculation result, the supply amount of the exhaust gas to the absorption device, the supply pressure, and the replacement timing of the absorption liquid are set, and the absorption device is operated under the set conditions. preferable.
[0028]
Further, in the operation method of the present invention, it is preferable to use a gas-liquid countercurrent type absorption device as the absorption device, more preferably an operation method using an exhaust gas purification equipment further having a chilled condenser and an activated carbon packed tower. preferable.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the exhaust gas purifying method and the operation method of the decomposition facility of the hardly decomposable halogen compound according to the present invention will be described in detail.
[0030]
1) Exhaust gas purification method
The exhaust gas purification method of the present invention comprises an exhaust gas containing a hardly decomposable halogen compound, preferably an exhaust gas generated from a reaction facility for dehalogenating a hardly decomposable halogen compound in a solvent, and an absorbing liquid. The hard-to-decompose halogen compound is removed by contact.
[0031]
The hardly decomposable halogen compounds to be used in the present invention are generally halogen compounds that are chemically stable and are not easily decomposed in a natural environment. Examples of the hardly decomposable halogen compounds include PCB, dioxins, polychlorinated benzofurans, polychlorinated benzene, DDT and other aromatic halogen compounds; BHC and other alicyclic halogen compounds; and the like.
[0032]
The solvent used in the dehalogenation reaction is not particularly limited as long as it is inert to the dehalogenation reaction of a hardly decomposable halogen compound. For example, n-hexane, n-heptane, n-octane, n-decane, kerosene, decalin, liquid paraffin, electric insulating oil (for example, electric insulating oil described in JIS C2320-1993), heavy oil (for example, in JIS K2205) A hydrocarbon solvent such as heavy oil as described above; an aromatic hydrocarbon solvent such as toluene and xylene; an aprotic polar solvent such as 1,3-dimethylimidazoline, sulfolane, and polyethylene glycol dialkyl ether; . Among these, the use of nonpolar organic solvents such as hydrocarbons and aromatic hydrocarbons is preferred, and the use of electrical insulating oil (for example, electrical insulating oil described in JIS C2320-1993) is particularly preferred.
[0033]
The method for dehalogenating a hardly decomposable halogen compound in a solvent is not particularly limited, and various decomposition methods for the hardly decomposable halogen compound can be used. Specifically, (1) a method for dehalogenating a hardly decomposable halogen compound using an alkali metal dispersion in a solvent, and (2) a hydrogen donor and an additive for the hardly decomposable halogen compound in a solvent. And alkali-catalyzed decomposition method (BCD method) heated at normal pressure in a nitrogen atmosphere, and (3) a hardly decomposable halogen compound, 1,3-dimethyl-2-imidazolidinone, sulfolane, polyethylene Chemical extraction decomposition method of reacting with an alkali such as sodium hydroxide or potassium hydroxide in an aprotic polar solvent such as glycol dialkyl ether, and (4) an organic alkali metal such as potassium tertiary butoxide to a hardly decomposable halogen compound. Organic alkali metal method for dehalogenation reaction by adding and heating, (5) In a solvent, a hardly decomposable halogen compound. The presence of a hydrogenation catalyst such as radium / carbon, in a hydrogen gas at normal catalytic hydrogenation dechlorination method of heating with pressure (Pd / C method) and the like.
[0034]
Among these, the alkali balance of the above (1) is preferable because the material balance of the compound derived from the hardly-decomposable halogen compound is clear, no harmful substances are produced as a by-product, and post-treatment after decomposition is easy. A method using a metal dispersion is preferable, and a method using a metal sodium dispersion obtained by dispersing metal sodium in a solvent as an alkali metal dispersion is more preferable.
[0035]
As the absorbing solution used for the contact treatment, those having excellent dissolving power with respect to a hardly decomposable halogen compound or the like are preferable. Specific examples thereof include n-hexane, n-heptane, n-octane, n-decane, kerosene, decalin, liquid paraffin, electric insulating oil (for example, electric insulating oil described in JIS C2320-1993), heavy oil (for example, , JIS K2205, etc.); aromatic hydrocarbons such as toluene and xylene; aprotic polar solvents such as 1,3-dimethylimidazoline, sulfolane, and polyethylene glycol dialkyl ether;
[0036]
Among these, the absorbent that has absorbed the hardly decomposable halogen compound can be used as it is as a solvent for the dehalogenation reaction, and the absorbed hardly decomposable halogen compound can be used again for the dehalogenation reaction. A solvent used when dehalogenating the halogen compound is more preferable.
[0037]
The contact treatment can be performed using an absorption device capable of bringing the exhaust gas into contact with the absorption liquid, for example, the absorption device shown in FIG. The absorption device shown in FIG. 1 is a gas-liquid countercurrent type absorption device that sends exhaust gas 2 from the lower part of the absorption tower 1 and sends absorption liquid 2 from the absorption tower 1.
[0038]
The size of the absorption tower 1 is not particularly limited, and a column having a predetermined size can be used depending on the flow rate of exhaust gas to be purified. In the absorption tower 1 shown in FIG. 1, the inner diameter is about 80 mm and the height is about 220 mm, but the diameter of the tower can be of various sizes depending on the gas flow rate.
[0039]
The middle part of the absorption tower 1 is provided with a packed part 5 filled with a packing 4, and the exhaust gas 2 is absorbed into the absorbing liquid 3 while the absorbing liquid 3 flows slowly through the fine gaps of the packing. It comes to come in full contact with.
[0040]
As the filler 4, the kind of the filler 4 is not limited as long as the exhaust gas 2 and the absorbing liquid 3 can be sufficiently contacted. For example, a regular packing created by assembling a wire mesh such as a sulzer packing or a sulzer lab packing, or an irregular packing such as Raschig ring or Perl saddle can be used.
[0041]
The flow of the absorbing liquid 3 is created by a diaphragm pump 6, and the flow rate is controlled by a flow meter 7. In order to ensure good flow of the absorbent 3, it is preferable to use the absorbent 3 heated to 25 to 30 ° C. with a heater (not shown).
[0042]
The purification method of the present invention was obtained by calculating the air weight concentration (CGW1) of the hardly decomposable halogen compound contained in the exhaust gas generated from the decomposition reaction tank from the formulas (1) to (3). The contact treatment condition is set from the calculation result, and the hardly decomposable halogen compound is removed from the exhaust gas under the set condition.
[0043]
Airborne concentration of persistent halogen compounds (CGW1, unit: g / m³N) can be determined as follows. In the following calculation, the solvent and the hardly-decomposable halogen compound are both non-polar components, and the concentration of the hardly-decomposable halogen compound is dilute, so it can be handled in an ideal liquid and ideal gas state according to Raoul's law. . That is, the activity coefficient can be handled as 1.
[0044]
(I) First, the liquid molar concentration (CLM1, unit: mol / mol) in the solvent of the hardly decomposable halogen compound is determined.
[0045]
[Formula 13]

[0046]
Ask from. Here, CLW1 represents the weight concentration (unit: kg / kg) of the hardly decomposable halogen compound in the solvent, Mw1 represents the molecular weight of the hardly decomposable halogen compound, and CLW2 represents the weight concentration (unit) of the solvent in the solution. : Kg / kg), and Mw2 represents the molecular weight of the solvent.
(ii) Next, the atmospheric partial pressure (CGM1, unit: Pa) of the hardly decomposable halogen compound is determined.
[0047]
[Expression 14]

[0048]
Ask from. Here, VP1 is a non-degradable halogen compound at a predetermined temperature (measurement temperature).Saturated vapor pressure(Unit: Pa), and CLM1 represents the molar concentration (unit: mol / mol) of the hardly decomposable halogen compound in the liquid.Saturated vapor pressureThe following relational expression (4) holds between VP (unit: Pa) and absolute temperature T (unit: ° K).
[0049]
[Expression 15]

[0050]
Here, a and b are constants that can be obtained from calibration curves obtained by measuring vapor pressures at various absolute temperatures T and plotting the measurement results.
[0051]
(iii) Next, the airborne concentration of the hardly decomposable halogen compound (CGW1, unit: g / m)³/ N)
[0052]
[Expression 16]

[0053]
Ask from. Here, 101.325 is a value for converting the unit of pressure Pa (pascal) into atm (atmospheric pressure).
[0054]
In the present invention, the air weight concentration (CGW1) of the hardly decomposable halogen compound thus obtained is contained in the exhaust gas generated from the theoretically predicted decomposition reaction tank or the exhaust gas after contact. The theoretically predicted concentration of the hard-to-decompose halogenated compound (hereinafter referred to as “theoretical concentration”).
[0055]
Further, even if a hardly decomposable halogen compound having a concentration of 1 to 100 times, preferably 5 to 50 times, more preferably 5 to 20 times the theoretical concentration is contained in the exhaust gas, the exhaust gas discharged to the outside Conditions for the contact treatment between the exhaust gas and the absorbing liquid are set so that the concentration of the hardly decomposable halogen compound contained therein is not more than the regulation value.
[0056]
Here, the "contact treatment conditions" include settings such as the amount of absorption liquid used, the amount of exhaust gas supplied per unit time when the exhaust gas is brought into contact with the absorption liquid, and the timing for replacing the absorption liquid with a new one. Conditions are included.
[0057]
Specifically, the filling amount and flow rate of the absorbent 3 in the absorption tower 1 can be determined based on the theoretical concentration. For example, when trans oil is used as the absorbent, the total amount of trans oil used is 5 to 10 liters, and the flow rate thereof can be usually set to 5 liters / min to 30 liters / minute.
[0058]
In addition, at the time of replacement of the absorbing solution determined from the theoretical concentration (the time when the absorption amount of the hardly decomposable halogen compound etc. set from the theoretical concentration is considered to have reached the saturated concentration), it should be replaced with a new absorbing solution. And
[0059]
In the absorption device shown in FIG. 1, since the absorption liquid 3 is circulated and used in a closed system, the absorption liquid is replaced after the operation of the decomposition reaction facility is stopped. For example, by connecting a joint to any place of the circulation flow path of the absorbent 3 shown in FIG. 1 and feeding the used absorbent from one side while feeding a new absorbent through the joint. The absorption liquid can be exchanged. According to this method, it is possible to replace the absorbing solution while continuing the operation of the decomposition reaction facility.
[0060]
The used absorbent may be transferred directly to the decomposition treatment facility for the dehalogenation reaction of the hardly decomposable halogen compound, transferred to a receiving tank and stored, and a certain amount of the solution is dehalogenated together. It can also be subjected to a chemical reaction. Alternatively, a tank for storing the used absorbent can be installed separately, and the used absorbent can be transferred and stored in the tank, and a certain amount can be used for the dehalogenation reaction.
[0061]
2) Operation method of the decomposition treatment facility of the hardly decomposable halogen compound
A second aspect of the present invention is a pretreatment facility for pretreating a hardly decomposable halogen compound or a material containing a hardly decomposable halogen compound, and a decomposition reaction facility for dehalogenating a hardly decomposable halogen compound in a solvent. A decomposition treatment of a hardly decomposable halogen compound, comprising a post-treatment facility for performing a post-treatment of the reaction product generated by the dehalogenation reaction, and an exhaust gas purification facility for purifying exhaust gas generated from the decomposition reaction facility This is how the facility operates.
[0062]
The outline of the decomposition treatment facility for the hardly decomposable halogen compound used in the present invention is shown in FIG. The decomposition treatment facility for the hardly decomposable halogen compound shown in FIG. 2 is composed of a pretreatment facility for the hardly decomposable halogen compound or the material containing the hardly decomposable halogen compound, a dehalogenation reaction facility for the hardly decomposable halogen compound, and a post-treatment facility. Each facility is further provided with an exhaust gas purification facility for purifying exhaust gas generated from each facility.
[0063]
(1) Pretreatment equipment
The pretreatment facility is a facility that receives a hardly decomposable halogen compound or a material containing a hardly decomposable halogen compound, and performs separation according to the type of the halogenated compound.
The content of the hardly decomposable halogen compound is different in the concentration of the hardly decomposable halogen compound and the property of the member depending on the type. For example, in the case of electrical equipment such as a transformer, the structure and material differ depending on the manufacturer, model number, etc., and subsequent process design needs to be performed accordingly.
[0064]
Examples of the inclusion of the hardly decomposable halogen compound that can be received in the pretreatment facility include waste containing the hardly decomposable halogen compound. Specific examples thereof include a hardly decomposable halogen compound-containing heat medium, a hardly decomposable halogen compound-containing electrical insulator, a hardly decomposable halogen compound for manufacturing a product using the hardly decomposable halogen compound, a contaminated oil containing a hardly decomposable halogen compound, Waste oils containing refractory halogen compounds and refractory halogen compounds, such as waste liquids of equipment cleaners that use refractory halogen compounds; waste pressure sensitive paper, insulating paper in electrical equipment, wipe paper for cleaning, Spacers, building materials for leakage locations, PP films for capacitor elements, sealant materials, used protective equipment, wire coating materials, insulating tapes, flame retardant resins, insulating materials in electrical equipment, electrical equipment such as transformers and capacitors, Contains hard-to-decompose halogen compounds such as electrical equipment containers, heat exchangers, aluminum for capacitor elements, various fasteners in electrical equipment, copper wires for transformer windings, etc. , Wood, synthetic resin or metals; hardly decomposable halogen compound treated containing hardly decomposable halogen compound; hardly decomposable halogen compound containing capacitors; hardly decomposable halogen compound containing trans; and the like.
[0065]
Among these, kerosene, decalin, electric insulating oil (electric insulating oil described in JIS C2320-1993), heavy oil (heavy oil described in JIS K2205) containing a hard-decomposing halogen compound as containing many hard-decomposing halogen compounds. ), Lubricating oils and mixtures thereof. Specifically, it is a transformer or a capacitor containing a hardly decomposable halogen compound.
[0066]
The received contents of the hardly decomposable halogen compound are disassembled, cut, broken, separated, etc., and the disassembled, cut, broken, and washed to recover the hardly decomposed halogen compound from the separated article.
[0067]
Examples of the cleaning method include an immersion method, a liquid circulation method, an ultrasonic method, and a bubbling method. The cleaning agent to be used must have excellent detergency, low risk of fire and explosion, low toxicity, and easy drying after cleaning. The hardly decomposable halogen compound recovered by washing is stored in a storage container together with the cleaning agent, separated from the cleaning agent as necessary, and sent to the next dehalogenation reaction step.
[0068]
In the case of a transformer or a capacitor containing a hardly decomposable halogen compound, the contents of the hardly decomposable halogen compound are enclosed in a sealed container. For this reason, the above-described recovery method such as cleaning is not preferable in terms of work efficiency. Therefore, in this case, it is preferable to perform an operation of extracting the hardly decomposable halogen compound from the transformer or the condenser.
[0069]
For example, in the case of a transformer (or condenser) containing PCB, the transformer (or condenser) is fixed, a hole is drilled at a predetermined position of the transformer (or condenser), and the hole is connected to a vacuum line. The hardly decomposable halogen compound can be taken out by sucking the hardly decomposable halogen compound from the hole while pressurizing the inside of the transformer (or condenser).
[0070]
In addition, in the transformer or the capacitor from which the hardly decomposable halogen compound is taken out as described above, the hardly decomposable halogen compound soaked into the fiber or the like may remain. In this case, for example, the inside is cleaned with a cleaning agent, or a hardly decomposable halogen compound or a member containing a hardly decomposable halogen compound is placed in a vacuum heating furnace, and the inside of the vacuum heating furnace is set to 0.01 to 50 mbar. The vacuum heating furnace is configured to reduce the pressure and heat the member to 250 to 650 ° C. while continuing the reduced pressure to carbonize the member and evaporate the hardly decomposable halogen compound or the insulating oil containing the hardly decomposable halogen compound. By condensing on the exhaust system from, it is possible to recover the hardly decomposable halogen compound or the insulating oil containing the hardly decomposable halogen compound.
[0071]
Further, the above pretreatment process is performed in a sealed space in order to prevent recontamination of the hardly decomposable halogen compound, and exhaust gas generated from the space is removed outdoors after being purified by an exhaust gas purification facility. It is preferable to discharge. Examples of the purification method include a method using an activated carbon packed tower in which activated carbon is adsorbed, a method using the exhaust gas purification equipment shown in FIG. The hardly decomposable halogen compound recovered by the exhaust gas purification equipment is sent to the next dehalogenation step.
[0072]
(2) Decomposition reaction equipment
In general, the decomposition reaction equipment contains a hardly decomposable halogen compound and a chemical (alkali) in a reaction tank together with an activator, a solvent, and the like, if desired, and at a predetermined temperature for a predetermined time using a stirrer. Is a facility for carrying out a dehalogenation reaction of a hardly decomposable halogen compound by stirring.
[0073]
There are no particular limitations on the decomposition reaction equipment, and examples include those that can be applied to various decomposition methods for hardly decomposed halogen compounds. Specifically, the equipment which can perform the dehalogenation reaction illustrated by the term of the purification | cleaning method of the exhaust gas mentioned above is mentioned. Among these, the alkali metal dispersion method is used because the material balance of the compound derived from the hardly-decomposable halogen compound is clear, no harmful substances are by-produced, and post-decomposition is easy. The decomposition reaction facility to be used is preferable, and the decomposition treatment facility using a metal sodium dispersion as the alkali metal dispersion is particularly preferable.
[0074]
The decomposition treatment facility usually comprises a reaction tank with a stirring device, a reaction temperature control device, and the like. The stirrer consists of at least a stirrer blade and a stirrer motor, and can freely adjust the rotation speed of the stirrer blade, sufficiently stir the hardly decomposable halogen compound and necessary chemicals, catalysts, solvents, etc., and stabilize the predetermined decomposition reaction It is preferable to use a stirrer that performs the target uniformly and uniformly. The temperature control device is a device that adjusts the temperature in the reaction tank (the temperature of the decomposition reaction) to a predetermined temperature, and before the reaction according to the operation management standard of the decomposition reaction facility determined according to the concentration of the hardly decomposable halogen compound. From the time until the end of the reaction, it is preferable to have a function of controlling the temperature, pressure, etc. within the standard range so as to ensure proper and safe operation.
[0075]
In any of the above-described dehalogenation reaction methods, the dehalogenation reaction is preferably performed in an inert gas atmosphere such as nitrogen gas or argon gas in order to perform the dehalogenation reaction safely.
The reaction product obtained by performing the dehalogenation reaction in the decomposition reaction facility is sent to the post-treatment facility.
[0076]
(3) Post-processing equipment
The post-treatment facility can separate and recover the decomposition products of the hardly decomposable halogen compounds, unreacted chemicals, activators, solvents, etc. contained in the reaction products, and finally discard or reuse them. It is equipment to be in a state.
[0077]
Specific examples of the post-treatment equipment include a centrifuge, a filtration device, a neutralization washing device, a liquid separation device, and a distillation device. Then, using these devices, operations such as separation and recovery of solids from the reaction product, decomposition of excess alkali, recovery of solvent, separation of produced salts, separation of catalysts, and the like are performed.
[0078]
For example, a reaction product obtained by dehalogenating a high-concentration hardly-decomposable halogen compound-containing material using an alkali metal dispersion includes a solvent such as insulating oil and a solid (polyphenylene type polymer, insulating oil, hydroxylation). Sodium, salt, water, etc.). The post-processing equipment includes a centrifuge for separating solid and liquid, a washing device, a liquid separation device, and the like, and an operation for separating oil and solids is performed using these devices.
[0079]
Moreover, when the content of a low-concentration hardly decomposable halogen compound is subjected to a dehalogenation reaction, a mixture of biphenyls, saline and insulating oil can be obtained by adding water to the reaction product. Next, the mixture was washed and allowed to stand, and then separated into oil, tar, and wastewater using a separator, the wastewater was evaporated using an evaporator, and the resulting solid was recovered and evaporated. An operation of recovering moisture as process water by a moisture recovery device is performed.
[0080]
In this case, water and alkali components can be recovered from the alkaline cleaning liquid used for the water washing, and this can be reused as a cleaning liquid for the decomposition product of the hardly decomposable halogen compound. In addition, in the case where a low-concentration halogen compound-containing material is decomposed with an alkali metal dispersion, an activator is added in addition to the alkali metal dispersion and the solvent. An aqueous solution used for washing the decomposition product of the decomposable halogen compound can also be used.
[0081]
In this way, post-decomposition can be performed in a short process without using a large-scale drainage facility, and high-polar components used in the reaction product can be removed by washing, and alkaline By adjusting the concentration of the cleaning liquid, the alkali component can be determined.
[0082]
In the decomposition treatment facility for a hardly decomposable halogen compound of the present invention, although not shown, the decomposition reaction of the hardly decomposable halogen compound is completed, and the content of the hardly decomposable halogen compound is constant. It is preferable to further install a measuring facility for confirming that the following has been reached.
[0083]
Examples of such measuring equipment include an apparatus for measuring the content of a hardly decomposable halogen compound such as ECD-GC (gas chromatography with an electron capture detector), GC-MS (gas chromatography-mass spectrum measuring apparatus), Examples include a separation / purification apparatus such as a silica gel column for extracting a part of the reaction mixture (sampling) after a predetermined time has elapsed from the start of the reaction, purifying the mixture, and making it measurable by the measuring apparatus. .
[0084]
(4) Exhaust gas purification equipment
The exhaust gas purification equipment is equipment for purifying exhaust gas discharged from the decomposition reaction equipment, pretreatment equipment and / or post-treatment equipment, but the exhaust gas discharged from the decomposition reaction equipment is targeted for purification. It is particularly preferable to do this.
[0085]
Examples of the exhaust gas purification equipment suitable for the present invention include the exhaust gas purification equipment shown in FIG. The exhaust gas purification equipment shown in FIG. 3 includes a gas-liquid countercurrent type absorption device 11 filled with an absorption liquid, a chill condenser 12, a mist separator 13, an activated carbon packed tower 14 filled with activated carbon, and a backfire preventer 15. It consists of. In addition, when content of the hardly decomposable halogen compound contained in exhaust gas is low, installation of the absorber 11 can be omitted.
[0086]
In the present invention, the in-air weight concentration (CGW1) of the hardly decomposable halogen compound contained in the exhaust gas generated from the reaction facility is calculated from the above formulas (1) to (3), and the obtained calculation is obtained. From the result, the optimum operating condition of the gas-liquid countercurrent type absorption device 11 is selected and performed.
[0087]
Here, the optimum operating condition of the gas-liquid countercurrent type absorption device 11 is that the hardly decomposable halogen compound contained in the exhaust gas is most efficient (that is, most advantageous from the viewpoint of manufacturing cost and operating cost). ) And an exhaust gas purification facility having a gas-liquid countercurrent type absorption device under operating conditions such that a hardly decomposable halogen compound contained in the exhaust gas subjected to the purification treatment discharged to the outside is less than a regulation value. It means to drive. Specifically, from the calculation result, the supply amount of exhaust gas to the absorption device, the supply pressure, the replacement timing of the absorption liquid, and the like are set, and the operation is performed under the set conditions.
[0088]
In the exhaust gas purification apparatus shown in FIG. 3, specifically, exhaust gas can be purified as follows.
(A) The exhaust gas generated from the decomposition reaction tank 8 is first cooled by the vent condenser 9, and the solvent vapor is liquefied (condensed) and returned to the reaction tank 8.
(B) Next, it passes through the seal trap 10 and is sent to the absorption device 11. The seal trap 10 is installed to prevent the backflow of exhaust gas.
(C) The exhaust gas sent to the absorption device 11 comes into contact with the absorbing solution, and the hardly decomposable halogen compound and the like contained in the exhaust gas are absorbed and removed. Selection of the contact condition at this time can be performed in the same manner as the method described in the section of the exhaust gas purification method described above.
[0089]
(D) The exhaust gas that has passed through the absorption process is sent to the cooling process. In the cooling step, the exhaust gas is rapidly cooled to 0 ° C. or less, preferably −10 ° C. or less by the deep-cooled condenser 12 to liquefy (condense) the gas component contained in the exhaust gas. By cooling the exhaust gas brought into contact with the absorbent by using the cryogenic condenser 12, it is possible to condense and remove a trace amount of hardly decomposable halogen compounds and the like. The deep-cooled condenser 12 is not particularly limited, and a known one can be used.
[0090]
That is, the temperature of the exhaust gas that has passed through the absorption process is normally warmed to 20 to 30 ° C., but is cooled to 0 ° C. or less, preferably −10 ° C. or less by passing through the chilled condenser 12, and the exhaust gas is exhausted. Most gas components in the gas are liquefied and condensed. The condensed liquid is collected by a condenser (not shown). The hardly decomposable halogen compounds and the like collected in the condenser are sent to a decomposition reaction facility and used for a dehalogenation reaction.
[0091]
(E) Next, the exhaust gas that has passed through the cryogenic condenser 12 is sent to the mist separator 13. The mist separator 13 is a separation device for removing a mist-like material (droplet-like material) from a gas. By passing the exhaust gas cooled by the deep-cooled condenser 12 through the mist separator 13, fine mist-like substances (solvent and hardly decomposable halogen compound components) that have not been collected in the condenser of the deep-cooled condenser 12 are gasified. It can be completely separated from the components. Although the installation of the mist separator 13 can be omitted, it is preferably installed from the viewpoint of completely removing the hardly decomposable halogen compound and the like.
[0092]
(F) Next, the exhaust gas that has passed through the mist separator 13 is allowed to pass through the activated carbon packed tower 14 filled with activated carbon, thereby performing adsorption treatment with activated carbon. The temperature at which the exhaust gas is brought into contact with the activated carbon is usually 0 ° C to 30 ° C. Moreover, the usage-amount of activated carbon is not restrict | limited in particular, It can set suitably according to the flow volume etc. of exhaust gas. There is no restriction | limiting in particular as activated carbon with which the activated carbon packed tower 14 is filled, Any of a coconut shell type | system | group, a wood type | system | group, and a coal type | system | group can be used, and granular coal and crushed coal can also be grind | pulverized and used.
[0093]
(G) Finally, the exhaust gas purified as described above is discharged to the outside through the backfire preventer 15. The backfire preventer 15 is installed to prevent the entry of fire from the outside. In the purification method of the present invention, exhaust gas generated from a decomposition reaction tank that performs a dehalogenation reaction of a hardly decomposable halogen compound is particularly targeted for purification. Therefore, since a combustible gas such as hydrogen gas is also included in the exhaust gas, it is preferable to install a backfire preventer for safety.
As described above, exhaust gas containing a hardly decomposable halogen compound or the like can be safely purified.
[0094]
【Example】
Example 1
PCB-containing transformer oil was detoxified using the hardly decomposable halogen compound decomposition treatment facility shown in FIG.
First, oil is removed from a discarded transformer in a pretreatment facility, and KC-300 (1 type of PCB, molecular weight: 334) 48 mg / kg, TCB (trichlorobenzene) 11 mg / kg, water containing 54 mg / kg 4400 kg (molecular weight: 260) was obtained.
[0095]
  Next, in order to design an exhaust gas treatment system, transformer oil and PCB (KC-300, molecular weight: 264) at an absolute temperature T (unit: ° K)Saturated vapor pressure(VP, unit: Pa) was measured. Then, a calibration curve was created with the obtained data as 1 / T (° K) on the horizontal axis and Log (VP) on the vertical axis, and the following equations (5) and (6) were obtained. In the following equation, VP2 is KC-300Saturated vapor pressureVP3 is the transformer oilSaturated vapor pressureAnd T1 and T2 represent absolute temperatures (° K).
[0096]
[Expression 17]

[0097]
[Formula 18]

[0098]
The VP2 at the reaction temperature (T ′) obtained from the equation (5) is obtained, and this is expressed by the equations (7), (8) and (9)
[0099]
[Equation 19]

[0100]
[Expression 20]

[0101]
[Expression 21]

[0102]
(Wherein, CLM2 represents the molar concentration of KC-300 in liquid, CLW2 represents the weight concentration of KC-300 in liquid, CLW3 represents the weight concentration of trans oil in liquid, and CGM2 represents the atmospheric concentration of KC-300. The atmospheric weight concentration of KC-300 (CGW2, unit: g / m).³N) was obtained. The calculation results are 266,667 to 386,667 ng / m.³Met.
[0103]
Assuming that this is a theoretical concentration, it is assumed that KC-300 having a concentration 15 times higher than this is contained in the exhaust gas (4,000,000 to 5,800,000 ng / m³), Contact treatment with an exhaust gas absorbing solution was performed.
[0104]
Next, in order to set the operating conditions of the absorber, the relationship between the superficial mass velocity (G) of the exhaust gas and the superficial mass velocity (L) of the absorbing liquid and the holding was examined. The experimental results are shown in FIG. As can be seen from FIG. 4, the superficial mass velocity (L) of the absorbing liquid (trans oil) is 1,300 to 4500 kg / m.²-If it is constant within the range of hr, the value of G is 30 to 300 kg / m²・ It was found that no hold-up occurred in the range of hr.
[0105]
Therefore, the superficial mass velocity (L) of the liquid is 2,400 kg / m²・ Hr, gas superficial mass velocity (G) is 250 kg / m²-It set as hr, the contact processing test was actually performed, and the relationship between the density | concentration of KC-300 in an absorption liquid and an exit | outlet density | concentration density | concentration (ratio) was investigated. The temperature of contact is 34.2-35.6 ° C. The results are shown in FIG. In FIG. 5, the horizontal axis represents the concentration (mg / kg) of KC-300 in the absorbing solution, and the vertical axis represents the actual measured concentration (outlet concentration) of KC-300 at the outlet of the absorber / absorber. Represents the theoretical concentration (theoretical concentration) of KC-300.
[0106]
As can be seen from FIG. 5, the measured concentration of KC-300 in the exhaust gas at the absorber outlet is 500 to 1,300 ng / m.³N, in the range of about 2 to 6 mg / kg of KC-300 in the absorbent (trans oil), it was 1/15 or less of the theoretical concentration, and the absorption rate was 99.9% or more.
From the above, the concentration of KC-300 at the absorber outlet is 1,300 ng / m.³When N exceeded, it was decided that it was necessary to replace the absorbent with a new one.
[0107]
Next, 4400 kg of the PCB-containing transformer oil obtained above was put in a decomposition reaction tank, and the inside was purged with nitrogen, followed by heating until the internal temperature reached 60 ° C. Thereto, 65 kg of metal sodium dispersion (including 11 kg of metal sodium) was added, 4.31 kg of water was added, and the mixture was stirred at 60 to 70 ° C. for 2 hours for dehalogenation reaction.
[0108]
At the same time, the exhaust gas generated from the decomposition reaction tank was sent to the reaction exhaust gas purification equipment shown in FIG. 3, and the exhaust gas was purified under the operating conditions set above.
[0109]
The exhaust gas analysis results at the following points A to E are shown in Table 1.
Point A: Seal trap 10
Point B: Exit of absorber 11
Point C: Exit of chilled condenser 12
D point: Exit of mist separator 13
E point: Exit of activated carbon packed tower 14
[0110]
The analysis of the exhaust gas was performed using a high-resolution gas chromatograph mass spectrometer (GC-MS) after obtaining a measurement sample with the exhaust gas sampling device shown in FIG. That is, the amount of exhaust gas (collected amount) shown in Table 1 is collected from each sampling port A to E, and 250 ml of distilled water (packed in a gas absorption bottle having an internal volume of 500 ml) is cooled with ice. Pass through and pass through XAD-2-resin (styrene resin adsorbent) tube and diethylene glycol (250 ml) under ice-cooling to remove impurities other than the hard-to-decompose halogenated compounds to obtain a sample for measurement. Were analyzed using high resolution GC-MS.
[0111]
In Table 1, the abbreviations have the following meanings.
Mono-CBs: Monochrome Robiphenyl
Di-CBs: Dichlorobiphenyl
Tri-CBs: Trichlorobiphenyl
Tetra-CBs: Tetrachlorobiphenyl
Penta-CBs: Pentachlorobiphenyl
Hexa-CBs: Hexachlorobiphenyl
Hepta-CBs: heptachlorobiphenyl
Octa-CBs: Octachlorobiphenyl
Nona-CBs: Nonachlorobiphenyl
Deca-CBs: Decachlorobiphenyl
Total-PCBs: Total amount of the above Mono-CBs to Deca-CBs
[0112]
[Table 1]

[0113]
Table 1 shows that hardly any decomposable halogen compound was detected from the exhaust gas discharged from the outlet of the activated carbon packed tower, and the exhaust gas was purified almost completely.
[0114]
Subsequently, the obtained reaction liquid was transferred to a heatable liquid separation apparatus installed in the post-treatment facility. While stirring the reaction solution, 10.93 kg of water was added dropwise at 60 to 70 ° C. over 1 hour. After completion of the dropwise addition of water, the mixture was further stirred at the same temperature for 30 minutes to completely decompose the excess metal sodium dispersion. Then, while raising the temperature of the reaction vessel to 80 ° C., 479.9 kg of alkaline water (containing 0.3 kg of sodium hydroxide) was added and stirred for 30 minutes. It left still at about 80 degreeC for 14.5 hours, and it liquid-separated into the process oil layer and the water layer, and fractionated the water layer. The separated aqueous layer was recovered by evaporation. The recovered amount was 474.4 kg.
[0115]
Add 25.6 kg of water and 474.4 kg of the water recovered by evaporation to the treated oil layer excluding the aqueous layer, stir at 80 ° C. for 1 hour, and let stand at 80 ° C. for 5 hours. The aqueous layer was separated to obtain a treated oil layer. This aqueous layer can be reused as alkaline water for washing the reaction solution by adding sodium hydroxide thereto and adjusting the concentration so as to obtain a predetermined alkali concentration.
[0116]
The total amount of the treated oil layer obtained as described above was 4465.17 kg, and contained 4440 kg of transformer oil, 25.02 kg of water, 0.02 kg of sodium hydroxide, 0.1 kg of biphenyl, and 0.02 kg of benzene, respectively. .
Further, almost no polychlorinated biphenyls were detected in the exhaust gas discharged from the outlet of the activated carbon packed tower of the exhaust gas purification equipment.
[0117]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the exhaust-gas purification | cleaning method which purifies exhaust gas containing a hardly decomposable halogen compound completely and efficiently, and the operating method of the decomposition processing facility of a hardly decomposable halogen compound are provided.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a gas-liquid countercurrent type absorber for carrying out an exhaust gas purification method of the present invention.
FIG. 2 is a conceptual diagram of a hardly decomposable halogen compound decomposition treatment facility suitable for the operation method of the hardly decomposed halogen compound decomposition treatment facility of the present invention.
FIG. 3 is a schematic diagram of an exhaust gas purification facility in the decomposition processing facility for the hardly decomposable halogen compound shown in FIG. 2;
4 is a diagram showing the relationship between the superficial mass velocity (G) of exhaust gas and hold-up (h) when exhaust gas is supplied to the absorber shown in FIG. 1. FIG.
FIG. 5 is a diagram showing the relationship between the concentration of PCB (KC-300) in the absorbing solution and the actual measured concentration (outlet concentration) / theoretical concentration of PCB (KC-300) at the outlet of the absorber. .
FIG. 6 is a diagram showing an apparatus for obtaining a measurement sample for analyzing exhaust gas.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Absorption tower, 2 ... Exhaust gas, 3 ... Absorption liquid, 4 ... Packing, 5 ... Packing part, 6 ... Diaphragm pump, 7 ... Flow meter, 8 ... Decomposition reaction tank, 9 ... Vent condenser, 10 ... Seal trap , 11 ... Absorber, 12 ... Cryogenic condenser, 13 ... Mist separator, 14 ... Activated carbon packed tower, 15 ... Backfire prevention device

Claims (9)

An exhaust gas purification method for removing a hardly decomposable halogen compound from an exhaust gas, wherein an air weight concentration (CGW1) of the hardly decomposable halogen compound contained in the exhaust gas is expressed by the formulas (1) to (3):

[In the formula, CLM1 represents the molar concentration (mol / mol) of the hardly decomposable halogen compound in the liquid, CLW1 represents the weight concentration (kg / kg) in the solution of the hardly decomposable halogen compound in the solvent, and Mw1 is difficult. This represents the molecular weight of the decomposable halogen compound, CLW2 represents the weight concentration of the solvent in the liquid (kg / kg), Mw2 represents the molecular weight of the solvent, and CGM1 represents the atmospheric partial pressure (Pa) of the hardly decomposable halogen compound. VP1 represents the saturated vapor pressure (Pa) of the hardly decomposable halogen compound at a predetermined temperature, and CGW1 represents the air weight concentration (g / m ³ N) of the hardly decomposable halogen compound contained in the exhaust gas. The exhaust gas purifying method is characterized in that the contact treatment condition is set from the calculation result obtained from the above calculation results, and the hardly decomposable halogen compound is removed from the exhaust gas under the set condition. The use amount of the absorbing liquid, the contact temperature or the replacement time of the absorbing liquid is set from the obtained calculation result, and the hardly decomposable halogen compound is removed from the exhaust gas under the set conditions. Item 2. The exhaust gas purification method according to Item 1. The exhaust gas purification method according to claim 1 or 2, wherein an insulating oil is used as the absorbing liquid. The exhaust gas purification method according to any one of claims 1 to 3, wherein the contact treatment is performed using a gas-liquid counter-current type absorber that performs a contact treatment between the absorbing liquid and the exhaust gas. The exhaust gas according to any one of claims 1 to 4, wherein the exhaust gas is an exhaust gas containing a hardly decomposable halogen compound generated from a reaction facility for performing a dehalogenation reaction of the hardly decomposable halogen compound in a solvent. Purification method. A pretreatment facility for pretreating a hardly decomposable halogen compound or a material containing a hardly decomposable halogen compound, a decomposition reaction facility for dehalogenating a hardly decomposable halogen compound in a solvent, and the dehalogenation reaction. A method for operating a decomposition treatment facility for a hardly decomposable halogen compound, comprising a post-treatment facility for performing a post-treatment of the generated reaction product, and an exhaust gas purification facility for purifying exhaust gas generated from each facility, The exhaust gas purification facility has an absorption device that performs a contact treatment between an absorbing solution and the exhaust gas, and the gas of the hardly decomposable halogen compound contained in the exhaust gas containing the hardly decomposable halogen compound generated from each facility. The medium weight concentration (CGW1) is expressed by the following formulas (1) to (3).

[In the formula, CLM1 represents the molar concentration (mol / mol) of the hardly decomposable halogen compound in the liquid, CLW1 represents the weight concentration (kg / kg) in the solution of the hardly decomposable halogen compound in the solvent, and Mw1 is difficult. This represents the molecular weight of the decomposable halogen compound, CLW2 represents the weight concentration of the solvent in the liquid (kg / kg), Mw2 represents the molecular weight of the solvent, and CGM1 represents the atmospheric partial pressure (Pa) of the hardly decomposable halogen compound. VP1 represents the saturated vapor pressure (Pa) of the hardly decomposable halogen compound at a predetermined temperature, and CGW1 represents the air weight concentration (g / m ³ N) of the hardly decomposable halogen compound contained in the exhaust gas. The optimum operating conditions of the gas-liquid countercurrent type absorber are selected from the obtained calculation results, and the preabsorber is operated under the conditions. How to operate a facility that decomposes halogenated compounds 7. The exhaust gas supply amount, supply pressure, and absorption liquid replacement timing to the absorption device are set from the calculation result, and the absorption device is operated under the set conditions. Of operation of a decomposition treatment facility for non-degradable halogen compounds. The operation method of the decomposition processing facility of the hardly decomposable halogen compound according to claim 6 or 7, wherein a gas-liquid countercurrent type absorption device is used as the absorption device. The operation method of the decomposition treatment facility for a hardly halogenated compound according to any one of claims 6 to 8, wherein an exhaust gas purification facility further comprising a chilled condenser and an activated carbon packed tower is used.

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