JP4922500B2 - Supercritical water reactor - Google Patents

Description

【００２０】
次いで、温度３００℃から６５０℃まで、５５０℃を除いて５０℃刻みに実験温度を設定し、同様の腐食実験を行ったところ、表１及び図１０に示す腐食実験結果を得た。図１０は表１の数字をグラフ化したものである。
実験に供した材料は、耐食性が高いと評価されている白金族元素のうちの白金（Ｐｔ）、イリジウム（Ｉｒ）、ルテニウム（Ｒｕ）、及びロジウム（Ｒｈ）と、白金族に次いで耐食性が高いと評価されているチタン｛Ｔｉ（ＡＳＴＭグレード１２）｝、タンタル（Ｔａ）、及び酸化アルミナ（Ａｌ₂ Ｏ₃ ）の７種類である。
【００２１】
尚、ロジウム（Ｒｈ）は、塩酸濃度２０質量％の塩酸水溶液に溶解し易く、反応器を作製して実物による腐食実験を行うことができないことが判ったので、他の材料の腐食条件と同じ条件でテストピースを塩酸水溶液に浸漬して、耐食性を評価した。ロジウムの腐食実験の結果は、表１で、３００℃で２７ｍｍ／ｙの腐食速度と表されているが、ロジウムが３００℃では塩酸水溶液に溶解してしまうので、その溶解速度を腐食速度として表示したものである。
【００２２】
ところで、実際の超臨界水処理では、反応器の容器壁の腐食速度が１ｍｍ／年未満であれば、腐食性が低く、反応器の材料として最も好ましい耐食性材料であると評価できる。また、腐食速度が１ｍｍ／年以上５ｍｍ／年未満のときには、その腐食速度は許容できる範囲内の腐食性であって、反応器の材料として採用可能な耐食性材料であると評価できる。
しかし、腐食速度が５ｍｍ／年を越えるときには、その腐食速度は許容できる範囲を超えており、反応器の材料として採用できる耐食性材料とは評価できない。
【００２３】
上述した腐食性（耐食性）の判定基準に従い、腐食試験で得た容器壁の腐食速度に基づいて、腐食試験に供した各材料が反応器に使えるかどうかについて、以下のように評価した。
イリジウム以外の材料、即ちチタン、タンタル（Ｔａ）、白金（Ｐｔ）、ルテニウム（Ｒｕ）、ロジウム（Ｒｈ）、及び酸化アルミナ（Ａｌ₂ Ｏ₃ ）の腐食性は、特定の温度範囲では、腐食速度が１ｍｍ／年以上５ｍｍ／年未満であって、許容できる範囲内に収まるものの、その温度範囲外では腐食速度が高く、そのままでは採用できない。
例えば、チタン、ルテニウム、ロジウムは、高温領域では、腐食速度が低いものの、４００℃以下の温度、特に３００℃では、腐食速度が極めて高い。逆に、タンタルは、４００℃以下の温度領域では、腐食速度が低いものの、４００℃以上の高温領域では、腐食速度が極めて高い。
また、酸化アルミナは、高温領域で、腐食速度は低いものの、割れが発生するので、反応器の耐食材料として使うことはできない。
【００２４】
更に言えば、耐食性の高いと評価されている白金族元素であっても、イリジウム以外の白金、ルテニウム（Ｒｕ）、及びロジウム（Ｒｈ）は特定の温度範囲を除いて耐食性に乏しく、イリジウムのみが常温から６５０℃までの温度範囲にわたり良好な耐食性を有する。
【００２５】
反応器内は、全域にわたって５５０〜６５０℃の温度範囲にあることが望まれるが、実際の運転においては、ノズル噴霧が悪化した場合に、反応器の一部、特に下部が４００℃以下の温度となることが考えられ、この範囲で、腐食速度が許容範囲以内であることが必要である。
例えば、チタンを使った反応器であれば、チタンの耐食性を機能させるためには、反応器を常に高温域に維持することが必要であって、特別の温度維持装置が必要になる。これでは、設備コストが嵩み、しかも運転が複雑になるという問題がある。
【００２６】
以上の実験結果から、本発明者は、４００℃以上の温度域で耐食性の良好なチタンと、４００℃以下の温度域で耐食性の良好なタンタルとを組み合わせることを考えた。
ところで、チタン、タンタルは、耐食性が良好な温度範囲が極めて臨界的に限定され、反応容器の温度が何らかの理由で耐食性を示す温度範囲から逸脱すると、腐食が著しく進行するという難点がある。一方、イリジウムは、常温から６５０℃までの温度範囲にわたり良好な耐食性を示すものの、機械的加工が難しいという問題があった。
【００２７】
そこで、本発明者は、ライニング等の機械的加工によってイリジウム層を形成する代わりに、化学的気相成長法（Chemical Vapor Deposition Process 、以下、ＣＶＤ法と言う）によって、酸化イリジウム層（ＩｒＯ₂ ）をチタン層又はタンタル層上に成長させることを着想した。酸化イリジウム層の耐食性を前述と同様な実験で調べたところ、イリジウム層と同じ耐食性を有することを実験で確認することができた。
本発明者は、実験を重ねて、チタン層上に、又はタンタル層上に、ＣＶＤ法によって酸化イリジウム層を成長させることにより、チタン層と酸化イリジウム層との複合耐食層、タンタル層と酸化イリジウム層との複合耐食層、又はタンタル層、チタン層、及び酸化イリジウム層の３層の複合耐食層を形成することができることを確認した。
【００２８】
そして、チタン層上に膜厚２５００〜３０００ｎｍの酸化イリジウム層をＣＶＤ法によって積層したＴｉ／ＩｒＯ₂ 複合耐食層で反応器の内壁面を被覆し、前述と同じ腐食実験を行った。
腐食実験の結果、腐食速度は、常温から６５０℃の範囲にわたってイリジウムと同様であって、例えば３００℃でプラス２ｍｍ／年以下であった。つまり、Ｔｉ／ＩｒＯ₂ 複合耐食層は、チタン層の耐食性が低い４００℃以下でも十分な耐食性を示し、また、常温から６５０℃の範囲で、ほぼイリジウムと同じ程度の耐食性を有する。
【００２９】
また、本発明者は、耐食層を形成する場合、単一の耐食性材料、例えばイリジウム層で耐食層を形成するより、寧ろ、多少異なる耐食性を有す複数の耐食材料、例えばチタン層と酸化イリジウム層との複合耐食層を形成する方が不測の条件下でもより一層確実な耐食性を示すと考えた。例えば、孔食状の腐食の場合、仮に酸化イリジウム層に孔食が生じたとしても、下層のチタン層にまで孔食が進行することは少ないからである。また、反応器内で不測の急激な温度低下が生じても、チタン層のみであれば、腐食の発生、進行が懸念されるが、酸化イリジウム層を表層に有するので、腐食が発生しない。
そこで、本発明者は、腐食され易い反応容器壁を上述の複合耐食層で被覆することにより、常温から６５０℃までの温度範囲にわたり、腐食速度の許容できる限度内で、即ち長期間にわたり安全に、有機塩素系化合物の超臨界水処理を行うことができるという、本発明を発明するに至った。
【００３０】
上記目的を達成するために、上述の知見に基づいて、本発明に係る超臨界水反応装置（以下、第１の発明と言う）は、超臨界水を収容する反応器を備え、有機塩素化合物を含有する被処理液を反応器内に導入して酸化剤により酸化分解する超臨界水反応装置において、
反応器内の温度を５５０℃以上６５０℃以下の範囲に制御する温度制御装置を備え、
反応器の被処理液と接する反応器壁面が、壁面上に設けられたタンタル又はタンタル合金からなるタンタル層と、タンタル層上に設けられたチタン又はチタン合金からなるチタン層と、チタン層上に積層された酸化イリジウム層との３層の複合耐食層で被覆されていることを特徴としている。
【００３１】
本発明では、被処理液の送入流量、超臨界水の送入流量、超臨界水生成のために反応器に送入する補給水の送入流量、及び補給水の温度の少なくともいずれかを調整して、反応温度を５５０℃以上６５０℃以下の範囲の温度に設定することにより、有機塩素化合物がＰＣＢ又はＰＣＢ類似化合物である場合、被処理液の酸化分解により生成した処理液中のＰＣＢ濃度を３ｐｐｂ以下にすることができる。
本発明で、ＰＣＢ類似化合物とは、ＰＣＢとほぼ同じような化学構造を有する化合物であって、例えばダイオキシン類、クロロベンゼン系化合物、クロロフェノール類等である。
また、本発明では、特定した複合耐食層で反応器の壁面を被覆しているので、上述の温度でも、生成塩酸による腐食雰囲気に抗して長期間にわたり安定し、ＰＣＢ等の有機塩素化合物を含む被処理液を処理することができる。
酸化イリジウム層の膜厚は、処理する有機塩素化合物、反応器内の塩酸濃度によって異なるが、実用的には、１５００ｎｍ以上とする。
【００３２】
本発明では、反応器の被処理液と接する反応器壁面が、壁面上に設けられたタンタル又はタンタル合金からなるタンタル層と、タンタル層上に設けられたチタン又はチタン合金からなるチタン層と、チタン層上に積層された酸化イリジウム層との３層の複合耐食層で被覆されている。
これにより、酸化イリジウム層が腐食し、更に、不測の事情により反応器の温度が４００℃より低下してチタン層が腐食した時にも、内側のタンタル層で耐腐食性を維持することができる。つまり、ＰＣＢ等の極めて有害な物質を取り扱う際に必要なフェイルセーフの考えに基づいている。
また、反応器内の温度分布に基づいて算出した温度が４００℃未満の領域の反応器壁面が、壁面上に設けられたタンタル又はタンタル合金からなるタンタル層と、タンタル層上に積層された酸化イリジウム層との複合耐食層で被覆されている。これにより、反応器の耐食性を更に高めることができる。
【００３３】
本発明で、複合耐食層で被覆するには、先ず、ニッケル合金等で形成された反応器壁上に既知のライニング法によってチタン層、タンタル層を被覆し、次いでチタン層又はタンタル層上にＣＶＤ法によって酸化イリジウム層を成長させる。
また、ニッケル合金層上にチタン層、タンタル層を被覆した被覆金属材を加工して、反応器を形成し、次いで反応器壁のチタン層又はタンタル層上にＣＶＤ法によって酸化イリジウム層を成長させる。
尚、本発明で「壁面を複合耐食層で被覆する」という表現は、反応器自体がチタン又はタンタルで形成され、その内壁面上に酸化イリジウム層を積層した態様も含む。
【００３４】
本発明で使用するチタン及びチタン合金は、ＪＩＳ規格又はＡＳＴＭ規格で規定されるものであって、例えばＪＩＳ規格では、純チタンはＪＩＳ１種から３種で規定されるチタン金属、チタン合金はチタンパラジウム合金として規定されるＪＩＳ１１種から１３種のチタン合金、及び他のチタン合金としてＴｉ−６Ａｌ−４Ｖ合金及びＴｉ−６Ａｌ−４ＶＥＬＩ合金がある。
また、ＡＳＴＭ規格では、純チタンはＡＳＴＭ Ｇｒａｄｅ１からＧｒａｄｅ４で規定されるチタン金属、チタン合金はチタンパラジウム合金として規定されるＡＳＴＭ Ｇｒａｄｅ７とＧｒａｄｅ１１のチタン合金である。また、ＡＳＴＭ規格でＧｒａｄｅ１２なども適用できる。
【００３５】
本発明で使用するタンタル及びタンタル合金は、ＪＩＳ規格又はＡＳＴＭ規格で規定されるものであって、純タンタルの他にも、タンタル−タングステン合金なども適用できる。
第１の発明で、チタン層又はチタン合金層、及びタンタル層又はタンタル合金層は、反応器の容器壁にライニングしても良く、また溶接法により肉盛りしても良い。また、ＨＩＰ処理によって反応器の容器壁に接合することもできる。
【００３６】
反応器が圧力バランス型反応器である場合には、本発明に係る超臨界水反応装置（以下、第２の発明という）は、超臨界水を収容する反応器を備え、有機塩素化合物を含有する被処理液を反応器内に導入して酸化剤により酸化分解する超臨界水反応装置において、
反応器内の温度を５５０℃以上６５０℃以下の範囲に制御する温度制御装置を備え、
反応器が、圧力容器と、圧力容器と相互に連通する反応カートリッジとの２重筒体であって、被処理液と、酸化剤とを反応カートリッジ内に供給し、かつ、圧力容器と反応カートリッジとの間に圧力バランス用ガスを供給して、反応カートリッジ内で被処理液を酸化分解する圧力バランス型反応器として構成され、
すくなくとも反応カートリッジの内壁面が、タンタル又はタンタル合金からなるタンタル層と、タンタル層上に設けられたチタン又はチタン合金からなるチタン層と、チタン層上に積層された酸化イリジウム層とからなる複合耐食材で形成されていることを特徴としている。
【００３７】
第２の発明では、温度制御装置が、被処理液の送入流量、超臨界水の送入流量、超臨界水生成のために反応器に送入する補給水の送入流量、及び補給水の温度の少なくともいずれかを調整することにより、反応器内の温度を５５０℃以上６５０℃以下の範囲に制御することができる。
【００３８】
また、別法として、反応カートリッジを、タンタル又はタンタル合金からなるタンタル層と、タンタル層の両面に設けられたチタン又はチタン合金からなるチタン層と、チタン層の両面に積層された酸化イリジウム層とからなる複合耐食材で形成しても良い。
これにより、酸化イリジウム層が腐食し、更に、不測の事情により反応器の温度が４００℃より低下してチタン層が腐食した時にも、内側のタンタル層で耐腐食性を維持することができる。
【００３９】
本発明の第３の発明は、超臨界水を収容する反応器を備え、有機塩素化合物を含有する被処理液を反応器内に導入して酸化剤により酸化分解する超臨界水反応装置において、
反応器内の温度を５５０℃以上６５０℃以下の範囲に制御する温度制御装置を備え、
反応器が、圧力容器と、圧力容器と相互に連通する反応カートリッジとの２重筒体であって、被処理液と酸化剤とを反応カートリッジ内に供給し、かつ、圧力容器と反応カートリッジとの間に圧力バランス用ガスを供給して、反応カートリッジ内で被処理液を酸化分解する圧力バランス型反応器として構成され、
処理流体が流れる処理流体流路と、処理流体流路に合流してアルカリ水溶液を処理液中に注入するアルカリ水溶液流路とを備え、アルカリ水溶液によって処理流体を４５０℃以下に中和急冷するようにした中和急冷部を反応器外に備え、
処理流体流路及びアルカリ水溶液流路の流路壁面が、壁面上に設けられたタンタル又はタンタル合金からなるタンタル層と、タンタル層上に積層された酸化イリジウム層との複合耐食層で被覆されている。
また、処理流体流路及びアルカリ水溶液流路の流路壁面を、壁面上に設けられたチタン又はチタン合金からなるチタン層と、チタン層上に設けられたタンタル又はタンタル合金からなるタンタル層と、タンタル層上に積層された酸化イリジウム層との複合耐食層で被覆するようにしても良い。
また、本発明の中和急冷部は、前記第１の発明または第２の発明と併用して用いるとよい。
【００４０】
圧力バランス型反応器では、中和急冷部を反応器の圧力容器と反応カートリッジとの間の環状部に備えて良い。
尚、第１及び第２の発明の超臨界水装置では、反応器は反応器内全域にわたり超臨界水域のみを形成し、亜臨界水域を形成しないようになっている。
【００４１】
【発明の実施の形態】
以下に、添付図面を参照し、実施形態例を挙げて本発明の実施の形態を具体的かつ詳細に説明する。
実施形態例１
本実施形態例は、第１の発明に係る超臨界水反応装置の実施形態の一例であって、図１は本実施形態例の超臨界水反応装置の構成を示すフローシート、及び図２は反応器の詳細を示す断面図である。
本実施形態例の超臨界水反応装置は、超臨界水の存在下で超臨界水反応により主としてＰＣＢを含む被処理液を処理する装置であって、図１に示すように、超臨界水反応を行う反応器として、縦型の耐圧密閉型反応器１２を備え、反応器１２から処理流体を流出させる処理流体管１４に、順次、処理流体を冷却する冷却器１６、反応器１２内の圧力を制御する圧力制御弁１８、及び、処理流体をガスと液体とに気液分離する気液分離器２０を備えている。
【００４２】
超臨界水反応装置１０は、超臨界水反応に供する被処理液を反応器１２に供給する供給系統として、インバータ制御又はストローク制御によって吐出量の調節が可能な被処理液ポンプ２４と、空気圧縮機２８とを備えて、被処理液管２２を介してＰＣＢを含む被処理液を反応器１２に送入し、かつ、空気送入管２６及び被処理液管２２を介して酸化剤として空気を被処理液と共に反応器１２に送入する。
図示しないが、必要に応じて超臨界水又は超臨界水生成用の補給水を反応器１２に補充するようにしてもよく、また、補給水を所望の温度に加熱する加熱器を設けることもできる。
更に、超臨界水反応装置１０は、反応器１２から出た直後の処理流体管１４に中和急冷部３０を備え、注入管３１から処理流体にアルカリ水溶液を注入して処理流体を温度４５０℃以下、好ましくは３５０℃以下に中和急冷するようになっている。
【００４３】
また、超臨界水反応装置１０は、被処理液の送入流量を調整することにより、反応器１２内の反応温度を例えば５５０℃に制御する温度制御装置３２を備えている。温度制御装置３２は、反応器１２内の温度を計測する温度計３４を有し、温度計３４の温度に基づいて被処理液ポンプ２４の吐出量を調節して被処理液の出口温度を調整することにより、反応温度を５５０℃以上６５０℃以下の範囲の設定温度に制御する。
温度制御装置３２の構成は、これに限らず、例えば超臨界水の送入流量を調整することにより、或いは超臨界水生成用の補給水の送入流量を調整することにより、更には補給水の送入温度を調整することにより、反応器１２内の反応温度を５５０℃以上６５０℃以下の範囲に制御することができる。
【００４４】
反応器１２は、図２に示すように、超臨界水処理時の圧力、例えば２３ＭＰａに抗する機械的強度を有する縦型筒状容器１２ａとして形成されている。容器１２ａの内壁は、内壁にライニングされたチタン層１２ｂ及びチタン層１２ｂ上にＣＶＤ法によって成長させた酸化イリジウム層１２ｃの複合耐食層で被覆されている。
【００４５】
ＣＶＤ法による酸化イリジウム層１２ｃの成長プロセスは、例えば、次のようにして行う。
すなわち、予めアセトンによりチタン層の脱脂処理を行った後、７００℃の水蒸気気流中にて酸化処理を行ってチタン層表面をチタン酸化物とする。
一方、塩化イリジウム（ＩｒＣ１₃ ）をアミルアルコールに溶解し、還流器を具備する加熱蒸留装置に入れ、温度９０℃で１０時間還流を継続することにより得た塩化イリジウムの塩化物の３／４をアミルアルコールと置換したイリジウム塗布液を生成する。
このイリジウム塗布液をチタン酸化物の表面に塗布し、室温にて自然乾燥した後、１１０℃で強制乾燥する。
次いで７００℃の水蒸気含有雰囲気下で１０分間熱分解反応処理を行う。この塗布→乾燥→熱分解反応処理を１０回繰り返して見掛け膜厚３０００ｎｍの酸化イリジウムの被覆層を形成した。
【００４６】
反応器１２は、被処理液管２２と接続し、被処理液及び空気を反応器１２内に流入させる流入口３６を上部に、処理流体管１４に接続し、処理流体を流出させる流出口３８を側壁に備えている。チタン層１２ｂは、チタン又はチタン合金からなるチタン層と、チタン層と容器壁との間に設けられた、タンタル又はタンタル合金からなるタンタル層との積層膜である。
【００４７】
中和急冷部３０は、図３に示すように、処理流体が流れる処理流体流路４０と、注入管３１を処理流体流路４０に合流させてアルカリ水溶液を処理流体中に注入するアルカリ水溶液流路４２とから構成されている。本実施形態例では、処理流体流路４０とアルカリ水溶液流路４２とは、Ｙ字状に合流しているが、直角に合流しても良い。
処理流体流路４０及びアルカリ水溶液流路４２の流路壁は、それぞれ、タンタル合金で形成されたタンタル管壁４４と、チタン又はチタン合金で形成され、タンタル壁の内周に設けられたチタン管壁４６と、チタン管壁４６上にＣＶＤ法によって成長させた酸化イリジウム層４７との３層構造で形成されている。尚、タンタル管壁４４の外周にニッケル合金鋼製管体を挿入し、ニッケル合金鋼製管体を圧力構造体としても良い。
【００４８】
中和急冷部３０を形成するには、先ず、タンタル合金の円柱体を形成し、次いで円柱体をドリリングして、貫通路を有するタンタル管壁４４を形成する。そして、タンタル管壁４４の貫通路内にチタン合金の溶融液を流し込み、放冷して固化させた後、ＨＩＰ処理を施して、タンタル合金相とチタン合金相との接合を確実にする。
次いで、チタン合金相をドリリングして、チタン管壁４６と、チタン管壁４６の外側に設けられたタンタル管壁４４とを形成する。続いて、チタン管壁４６上にＣＶＤ法によって酸化イリジウム層４７を成長させることにより、処理流体流路４０及びアルカリ水溶液流路４２を形成することができる。
また、別の作製方法として、タンタル合金の円柱体を形成し、次いで円柱体をドリリングして、貫通路を有するタンタル管壁４４を形成し、チタン管壁４４上にチタン合金を溶接法等により肉盛りしてチタン壁４６を設け、続いてチタン管壁４６上にＣＶＤ法によって酸化イリジウム層４７を成長させる。
【００４９】
別法として、中和急冷部３０の処理流体流路４０及びアルカリ水溶液流路４２の流路壁を、それぞれ、純タンタル又はタンタル合金からなるタンタル管壁と、タンタル管壁上にＣＶＤ法によって成長させた酸化イリジウム層とから構成しても良い。
別法の中和急冷部３０を作製するには、例えば、先ず、タンタル合金の円柱体を形成し、次いで円柱体をドリリングして、貫通路を有するタンタル管壁を形成する。次いで、ＣＶＤ法によって酸化イリジウム層をタンタル管壁面に成長させる。
【００５０】
本実施形態例では、温度制御装置３２によって反応器１２内の温度を６００℃に制御することにより、ＰＣＢを含む被処理液を超臨界水処理により完全に分解して処理液のＰＣＢの残留量を３ｐｐｂ以下に抑えることができる。
また、チタン合金層１２ｂと酸化イリジウム層１２ｃとの複合耐食層が、反応器１２の耐食層として確実に機能する。また、仮に、反応器１２内の温度が４００℃以下に低下しても、酸化イリジウム層１２ｃが表層にあるので、腐食が進行するようなことは生じない。
中和急冷部３０は、酸化イリジウム層４７で被覆されているので、腐食が進行するようなことは生じない。万一、酸化イリジウム層４７が腐食しても、温度が高い通常の状態では、チタン管壁４６が耐食性を維持し、逆に、温度が予期せずに例えば４００℃以下に低下した状態では、チタン管壁４６は腐食されるものの、その外側のタンタル管壁４４が耐食性を維持する。
【００５１】
実施形態例２
本実施形態例は、第２の発明に係る超臨界水反応装置の実施形態の一例であって、図４は本実施形態例の超臨界水反応装置の構成を示すフローシート、図５（ａ）は反応器の詳細を示す断面図、及び図５（ｂ）は反応カートリッジを形成する複合耐食材の構成を示す図５（ａ）の線Ｉ−Ｉの断面図である。図４及び図５中、図１から図３に示す部位、部品と同じものには同じ符号を付し、その説明を省略する。
本実施形態例の超臨界水反応装置５０は、圧力容器と、反応容器と相互に連通する反応カートリッジとからなる圧力バランス型反応器を反応器として備えた超臨界水反応装置であって、図４及び図５に示すように、反応器５２の構成、中和急冷部が反応器５２内に内蔵されていること、及び反応器５２に圧力バランス用の空気が送入されていることを除いて、実施形態例１と同じ構成を有する。
【００５２】
圧力バランス型反応器５２は、図５（ａ）に示すように、外筒として設けられた圧力容器５４と、圧力容器５４内に内筒として設けられた反応カートリッジ５６との２重筒体として形成され、反応カートリッジ５６の内部５８は、超臨界水反応の反応域として構成されている。
圧力容器５４は、反応圧力に対抗するために、厚肉の高強度鋼製耐圧円筒型容器として形成されていて、圧力容器５４と反応カートリッジ５６との間の環状部６２は、後述するように圧力バランス用のガスとしての空気層であって、腐食性雰囲気ではない。
一方、反応カートリッジ５６は、図５（ｂ）に示すように、チタン又はチタン合金で形成された薄肉の有蓋有底円筒体５６ａとして形成され、更に、有蓋有底円筒体の内表面（内部５８側）にＣＶＤ法によって成長させた酸化イリジウム層５６ｂが積層されている。反応カートリッジ５６の底部と圧力容器５４の底部との間に多少の間隙を有するように圧力容器５４内に配置されている。
【００５３】
圧力容器５４と反応カートリッジ５６との間に、連通孔６０を介して反応カートリッジ５６の内部と連通する環状部６２が形成されており、ノズル６４を経て反応カートリッジ５６に流入した空気と同じ圧力の空気が環状部６２に導入されているので、反応カートリッジ５６の内外では圧力差が殆ど無く、環状部６２と反応カートリッジ５６内とは、圧力がバランスしている。
換言すれば、圧力容器５４は、超臨界水処理時の圧力、例えば２３ＭＰａに抗する強度を備え、反応カートリッジ５６は、反応器５２の内圧力を受けないようにして反応域を区画する耐腐食性の隔壁として機能している。
尚、環状部６２に空気を導入するのは、空気が非腐食性流体であるからである。
【００５４】
反応器５２は、圧力容器５４と反応カートリッジ５６とを貫通して反応カートリッジ５６の内部に突出したノズル６４と、反応カートリッジ５６から環状部６２を通って反応器５２外に処理流体を流出させる処理流体導管６６と、環状部６２内の処理流体導管６６に設けられた中和急冷部６８と、環状部６２に圧力バランス用ガスとして空気を送入する空気送入ノズル７０とを備えている。
中和急冷部６８は、実施形態例１の中和急冷部３０と同じ構造（図３参照）であって、注入管３１が接続され、処理流体にアルカリ水溶液を注入し、４５０℃以下に中和急冷するようになっている。
ノズル６４は被処理液管２２（図４参照）に、処理流体導管６６は処理流体管１４に、それぞれ、接続されている。また、空気送入ノズル７０は、空気送入管２６から分岐した空気送入枝管７２（図４参照）に接続され、空気を環状部６２に導入し、次いで連通孔６０を介して反応カートリッジ５６内部に流入させ、酸化剤の一部とする。
【００５５】
本実施形態例では、実施形態例１と同様に、温度制御装置３２によって反応器５２、正確には反応カートリッジ５６内の温度を例えば６００℃に制御することにより、ＰＣＢを含む被処理液を超臨界水処理により完全に分解して処理液のＰＣＢの残留量を３ｐｐｂ以下に抑えることができる。
また、反応器１２内の温度が６００℃に制御されているので、チタン合金で形成され、更に酸化イリジウム層で被膜された反応カートリッジ５６は、反応域を確保する耐食壁として確実に機能する。中和急冷部６８も、実施形態例１と同様に機能し、同様の効果を有する。
【００５６】
実施形態例３
本実施形態例は、第２の発明に係る超臨界水反応装置の実施形態の一例であって、図６（ａ）は実施形態例３の反応器の詳細を示す断面図、図６（ｂ）は反応カートリッジの外筒を形成する複合耐食材の構成を示す、図６（ａ）の線Ｉ−Ｉの断面図、及び図６（ｃ）は反応カートリッジの内筒を形成する複合耐食材の構成を示す、図６（ａ）の線II−IIの断面図である。図６中、図５と同じ部位、部品には同じ符号を付し、その説明を省略している。
本実施形態例の超臨界水反応装置は、反応器７６の構成が、反応器５２と異なり、反応カートリッジ内に内筒を有することを除いて、実施形態例２と同じ構成を有する。
【００５７】
反応器７６は、図６（ａ）に示すように、圧力容器５４と、圧力容器５４と相互に連通する反応カートリッジ８０とからなる圧力バランス型反応器であり、反応カートリッジ８０は、外筒８２と、外筒８２内に収容され、超臨界水反応の反応域を内部に有する内筒８４とから構成されている。
外筒８２は、実施形態例２の反応カートリッジ５６と同じように、図６（ｂ）に示すように、チタン又はチタン合金製の有底有蓋円筒体８２ａとして形成され、更に円筒体８２ａの内面がＣＶＤ法によって成長させた酸化イリジウム層８２ｂで被覆されている。
内筒８４は、上端が開口し、底部が逆円錐状のチタン又はチタン合金製の有底円筒体８４ａとして形成され、更に、図６（ｃ）に示すように、円筒体８４ａの内外面が、ＣＶＤ法によって成長させた酸化イリジウム層８４ｂで被覆されている。
尚、内筒８４はこの形状に限るものではなく、傘を上下逆にしたような形状のものなど、ノズルから噴出し下方に向かう流体の流れを反転させて上方に向かわせるようにできる限り、その形状に制約はない。
【００５８】
ノズル６４から流入した被処理液は、内筒８４の内部で超臨界水処理され、処理流体となって上端の開口から外筒８２と内筒８４との間の環状部８６に流入し、環状部８６を流下して外筒８２の底部に入り、外筒８２の底部に接続された処理液導管８８を介して処理流体管１４に流出する。
圧力容器５４内の処理流体導管８８には、実施形態例１の中和急冷部３０と同じ構造（図３参照）の中和急冷部９０が設けてあって、注入管３１が接続され、処理液にアルカリ水溶液を注入し、４５０℃以下に中和急冷するようになっている。
空気送入ノズル７０は、空気を環状部６２に導入し、次いで連通孔６０を介して反応カートリッジ８０の上端開口から反応カートリッジ８０内部に流入させ、酸化剤の一部とする。
以上の構成により、本実施形態例の超臨界水反応装置も、実施形態例２と同じ効果を有する。
【００５９】
実施形態例４
本実施形態例は、第２の発明に係る超臨界水反応装置の実施形態の一例であって、図７は反応器の詳細を示す断面図である。図７中、図６と同じ部位、部品には同じ符号を付し、その説明を省略する。
本実施形態例の超臨界水反応装置は、中和急冷部９２が反応器外に設けられていること、及びそれに関連して反応器９４の構成が異なることを除いて、実施形態例３と同じ構成を有する。
反応器９４は、図７に示すように、中和急冷部９２が反応器の外部に設けてあることを除いて、実施形態例３の反応器７６と同じ構成を備え、反応カートリッジの外筒８２は圧力容器５４の底部に接し、処理流体管１４が直接圧力容器５４の底部を貫通して外筒８２の内部に連通している。
中和急冷部９２は圧力容器５４の底部に接するようにして処理流体管１４に設けてある。
本実施形態例の反応器９４では、実施形態例３の反応器７６に比べて中和急冷部９２の取り付けが容易である。
尚、実施形態例２の超臨界水反応装置の反応器５２で、反応カートリッジ５６の底部を圧力容器５４の底部上に配置し、環状部６２に設けた中和急冷部６８に代えて、図７に示すように中和急冷部９２を圧力容器５４の底部に接するように設けることもできる。
【００６０】
【発明の効果】
本発明によれば、反応温度を５５０℃以上６５０℃以下の範囲に制御することにより、有機塩素化合物を含有する被処理液を超臨界水処理して無害化することができ、例えばＰＣＢ又はＰＣＢ類似化合物等の場合、処理流体中のＰＣＢ濃度を３ｐｐｂ以下にすることができる。
また、本発明によれば、反応器壁又は反応カートリッジを特定する複合耐食層で被覆し、又は特定する複合耐食材で形成することにより、反応器の腐食の進行を抑制して、有機塩素化合物、例えばＰＣＢ又はＰＣＢ類似化合物を含有する被処理液を超臨界水処理して処理流体中のＰＣＢ濃度を３ｐｐｂ以下にする処理を長期間にわたり安定して可能とする超臨界水反応装置を実現している。
【図面の簡単な説明】
【図１】実施形態例１の超臨界水反応装置の構成を示すフローシートである。
【図２】実施形態例１の反応器の詳細を示す断面図である。
【図３】中和急冷部の断面図である。
【図４】実施形態例２の超臨界水反応装置の構成を示すフローシートである。
【図５】図５（ａ）は実施形態例２の反応器の詳細を示す断面図、及び図５（ｂ）は反応カートリッジを形成する複合耐食材の構成を示す図５（ａ）の線Ｉ−Ｉの断面図である。
【図６】図６（ａ）は実施形態例３の反応器の詳細を示す断面図、図６（ｂ）は反応カートリッジの外筒を形成する複合耐食材の構成を示す、図６（ａ）の線Ｉ−Ｉの断面図、及び図６（ｃ）は反応カートリッジの内筒を形成する複合耐食材の構成を示す、図６（ａ）の線II−IIの断面図である。
【図７】実施形態例４の反応器の詳細を示す断面図である。
【図８】従来の超臨界水反応装置の構成を示すフローシートである。
【図９】従来の圧力バランス型反応器の構成を示す断面図である。
【図１０】腐食実験の結果を示すグラフである。
【符号の説明】
１０ 実施形態例１の超臨界水反応装置
１２ 反応器
１２ａ 縦型筒状容器
１２ｂ チタン合金層
１２ｃ 酸化イリジウム層
１４ 処理流体管
１６ 冷却器
１８ 圧力制御弁
２０ 気液分離器
２２ 被処理液管
２４ 被処理液ポンプ
２６ 空気送入管
２８ 空気圧縮機
３０ 中和急冷部
３１ 注入管
３２ 温度制御装置
３４ 温度計
３６ 流入口
３８ 流出口
４０ 処理流体流路
４２ アルカリ水溶液流路
４４ タンタル管壁
４６ チタン管壁
４７ 酸化イリジウム層
５０ 実施形態例２の超臨界水反応装置
５２ 反応器
５４ 圧力容器
５６ 反応カートリッジ
５６ａ チタン又はチタン合金で形成された薄肉の有蓋有底円筒体
５６ｂ 酸化イリジウム層
５８ 反応カートリッジの内部
６０ 連通孔
６２ 環状部
６４ ノズル
６６ 処理流体導管
６８ 中和急冷部
７０ 空気送入ノズル
７２ 空気送入枝管
７６ 実施形態例３の反応器
８０ 反応カートリッジ
８２ 外筒
８２ａ チタン又はチタン合金製の有底有蓋円筒体
８２ｂ 酸化イリジウム層
８４ 内筒
８４ａ チタン又はチタン合金製の有底円筒体
８４ｂ 酸化イリジウム層
８６ 環状部
８８ 処理流体導管
９０ 中和急冷部
９２ 実施形態例４の中和急冷部
９４ 実施形態例４の反応器
１００ 従来の超臨界水反応装置
１０２ 反応器
１０４ 超臨界水領域
１０６ 仮想的界面
１０８ 亜臨界水領域
１１０ 流入管
１１２ 被処理液ライン
１１４ 空気ライン
１１５ 超臨界水ライン
１１６ 中和剤ライン
１１８ 処理流体ライン
１２０ 亜臨界水ライン
１２２ 亜臨界排水ライン
１３０ 圧力バランス型反応器
１３１ 外円筒体
１３２ 反応カートリッジ
１３３ 入口ノズル
１３４ 反応域
１３５ 圧力バランス用ガス送入口
１３６ 環状部
１３７ 上部間隙
１３８ 反応器流出管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a supercritical water reactor for supercritical water treatment of a liquid to be treated, particularly a liquid to be treated containing an organic chlorine-based compound such as PCB, and more particularly, a supercritical water reactor that completely decomposes PCB and renders it harmless. The present invention relates to a supercritical water reactor optimal for critical water treatment.
[0002]
[Prior art]
Along with the growing awareness of environmental problems, the decomposition and detoxification of environmental pollutants has attracted attention as one of the fields of application of supercritical water reactors.
That is, due to the supercritical water reaction utilizing the reaction medium properties of supercritical water, harmful and hardly decomposable organic substances that have been difficult to decompose by the prior art, such as PCB (polychlorinated biphenyl), dioxin, organic chlorine It is an attempt to decompose a system solvent or the like and convert it into harmless products such as carbon dioxide, water and inorganic salts.
[0003]
Supercritical water refers to water that is in a supercritical state, that is, water that exceeds the critical point of water, and more specifically, a critical temperature, that is, a temperature above 374.1 ° C., and a critical pressure of water. That is, the water in a state under a pressure of 22.04 MPa or more.
Supercritical water has a high ability to dissolve organic substances, and can completely dissolve non-polar substances that are abundant in organic compounds. Conversely, the ability to dissolve inorganic substances such as metals and salts is extremely low. Supercritical water can be mixed with a gas such as oxygen or nitrogen at an arbitrary ratio to form a single phase.
[0004]
Here, with reference to FIG. 8, the basic structure of the conventional supercritical water reaction apparatus which supercritical water-processes the to-be-processed liquid containing an organic chlorine type compound is demonstrated. FIG. 8 is a flow sheet showing the configuration of a conventional supercritical water reactor.
The supercritical water reactor 100 is a so-called “moder process type” device that is conventionally said to be the most suitable for the oxidative decomposition of organic chlorine-based hardly decomposable organic substances in which salts are deposited during supercritical water treatment. In addition, a pressure-resistant sealed vertical reactor 102 having a subcritical water region at the bottom is provided, and a salt precipitated as a solid in supercritical water is settled and separated in the subcritical water region at the bottom of the reaction vessel. .
[0005]
As shown in FIG. 8, a supercritical water region 104 in which supercritical water is retained is formed in the upper part of the reactor 102, and the condition above the critical point of water, that is, the supercritical condition is maintained. On the other hand, in the lower part of the reactor 102, a subcritical water region 108 is formed via a virtual interface 106 with the supercritical water region 104, and subcritical water lower than the critical temperature of water is retained.
Connected to the upper part of the reactor 102 is an inflow pipe 110 through which a liquid to be treated for supercritical water treatment and an oxidizing agent flow into the supercritical water region 104.
The inflow pipe 110 is joined with a liquid line 112 to be processed for supplying a liquid to be processed having an organic chlorine compound to be processed by a supercritical water reaction, and an air line 114 for supplying air as an oxidizing agent for oxidizing organic substances. is doing.
If necessary, a supercritical water line 115 for supplying supercritical water or makeup water for generating supercritical water to the supercritical water region may be connected to the inflow pipe 110.
[0006]
Further, a neutralizer line 116 for supplying an alkali neutralizer to neutralize hydrochloric acid generated by the organic chlorine compound in the liquid to be treated is connected to the liquid line 112 to be treated.
In this example, normally, the liquid to be treated and the neutralizing agent are supplied to the reactor 102 through the inflow pipe 110 and are atomized downward by air as an oxidant, so that the supercriticality in the reactor 102 is obtained. Sprayed into the water area 104. The organochlorine compound in the sprayed liquid to be treated is instantly oxidized and decomposed in the supercritical water region 104. As a result of the supercritical water reaction, the chlorine of the organochlorine compound contained in the liquid to be treated is neutralized with an alkali neutralizer to form a salt, and moves from the supercritical water area to the subcritical water area.
Further, a processing fluid line 118 is connected to the upper part of the reactor 102, and organic substances in the liquid to be processed are mainly converted into water and carbon dioxide by the supercritical water reaction, and are processed from the supercritical water region 104 together with the processing fluid. It flows out through line 118.
[0007]
On the other hand, a subcritical water line 120 and a subcritical drainage line 122 are connected to the lower part of the reactor 102, and the subcritical water line 120 supplies subcritical water to the subcritical water area 108. The subcritical water in which the salt generated by the supercritical water reaction and the neutralization reaction is dissolved is discharged from the subcritical water area 108 as waste water.
Although not shown, the processing fluid line 118 and the subcritical drainage line 122 include a pressure control device that maintains the pressure in the reactor 104 at a predetermined pressure, a cooler that lowers the processing fluid and the subcritical drainage to a predetermined temperature, A decompression device for reducing the pressure to a predetermined pressure, a gas-liquid separator, and the like are provided.
[0008]
[Problems to be solved by the invention]
However, when the above-described conventional supercritical water treatment apparatus tries to supercritical water treat a liquid to be treated containing a high concentration of PCB, the following problems have occurred.
First, the PCB content of the treatment liquid is allowed by the discharge standard at a reaction temperature slightly exceeding the critical temperature of water (374.1 ° C.), that is, in the range of 450 ° C. to 500 ° C. It was extremely difficult to make it below 3 ppb. Conversely, it is expected that higher reaction temperatures will be required.
[0009]
Second, there are two problems caused by the two-zone method in which a supercritical water area and a subcritical water area are formed in the reactor.
One of the problems was that the corrosion of the reactor wall, particularly the corrosion near the boundary between the two regions, was significant. Usually, since the neutralization reaction proceeds simultaneously with the supercritical water reaction, the corrosion problem does not occur. However, if the neutralization is incomplete in some cases, the corrosion becomes a problem. In the conventional method, since there are a high-temperature supercritical water region and a low-temperature subcritical water region in the reactor, there is always a severely corrosive region, which is an obstacle to the practical application of PCB supercritical water treatment. It was.
Second, if the sprayed state of the liquid to be treated is not good in the conventional method, the PCB or the like may enter the subcritical water area without being completely decomposed. In this case, since the temperature of the subcritical water area is low, the undecomposed matter mixed in the subcritical water area remains as it is without being decomposed, and is discharged as waste water from the subcritical water area. There was a problem that the content exceeded the emission standard.
[0010]
Third, when the concentration of organic chlorine in the liquid to be treated is high as in the case of treating PCB, there are many unclear points in the mechanism of neutralization reaction and salt formation and separation. The process of completely neutralizing hydrochloric acid generated from organic chlorine in the reactor as in the prior art is actually difficult and has a problem of low certainty.
[0011]
Therefore, as an improvement plan for the neutralization treatment, a neutralization and quenching section for quenching and neutralizing by injecting an alkaline aqueous solution into the processing fluid is provided at the outlet or downstream of the reactor, and the aqueous alkali solution is injected outside the reactor to inject the processing fluid into Attempts have been made to cool quickly.
However, in this method, since the treatment fluid flows out of the reactor and enters the neutralization quenching section for neutralization, a large amount of hydrochloric acid generated by the supercritical water reaction exists in the reactor. For this reason, nickel alloys such as Inconel 625, which have been used as an anticorrosion layer on the inner wall of the reactor, have a problem that corrosion due to hydrochloric acid is remarkably difficult to use.
Also, in the quenching neutralization part, the corrosion of the pipe up to the point where the neutralization reaction between the alkaline aqueous solution and the processing fluid ends is significant, and even if nickel alloy is used for the pipe, there is a problem that long-term use is difficult. .
[0012]
Furthermore, an attempt has been made to employ a pressure balance type reactor in combination with a neutralization quenching section.
As shown in FIG. 9, the pressure balance type reactor 130 is provided as an outer cylindrical body 131 formed as a pressure vessel, and an inner cylindrical body communicating with the outer cylindrical body 131, and contains supercritical water. It is formed as a double cylinder with the reaction cartridge 132 forming the reaction zone.
From an inlet nozzle 133 connected to the inflow pipe 110 (see FIG. 8), a liquid to be treated and an oxygen-containing gas such as air as an oxidant are introduced into the reaction zone 134 in the reaction cartridge 132 and used for pressure balancing. For example, air is supplied as a pressure balancing gas from the gas inlet 135 to the annular portion 136 between the outer cylindrical body 131 and the reaction cartridge 132.
The pressure balancing gas flows into the reaction zone 134 from the annular portion 136 via the upper gap 137 between the pressure vessel 131 and the reaction cartridge 132 and is consumed as part of the oxidant.
[0013]
The liquid to be treated that has flowed into the reaction zone 134 in the reaction cartridge 132 is oxidized and decomposed by oxygen in supercritical water, and flows out from the reactor outflow pipe 138. The neutralization / quenching section is provided inside or outside the pressure vessel 132 downstream of the reaction cartridge 132.
In the conventional pressure balance type reactor, since there is almost no pressure difference between inside and outside, the reaction cartridge 132 can be formed with a thin wall thickness using a non-pressure vessel, so the reaction cartridge 132 is made of an expensive corrosion-resistant metal, for example, a nickel alloy such as Inconel 625. Even if it forms in, there exists an advantage that cost does not increase. Further, since the annular portion 136 is not a corrosive atmosphere, the outer cylindrical body 131 is not necessarily formed of the same material as the reaction cartridge 132, and is usually formed of heat-resistant / pressure-resistant carbon steel or stainless steel. .
However, even a reaction cartridge formed of an expensive nickel alloy has a problem that corrosion due to hydrochloric acid is remarkable and it must be replaced in a short period of time.
[0014]
Accordingly, an object of the present invention is to treat a liquid to be treated, particularly a liquid to be treated containing PCB or the like at a high concentration, by supercritical water treatment, and to obtain a PCB concentration of 3 ppb or less which is permitted by the discharge standard. An apparatus for reducing the concentration, which is to provide a supercritical water treatment apparatus that can be stably operated over a long period of time.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor (1) establishes a reaction temperature capable of supercritical water treatment of a liquid to be treated having a high organic chlorine concentration such as PCB to a PCB concentration of 3 ppb which is permitted by the discharge standard. (2) It was considered necessary to establish a reactor material that can be used under the temperature conditions and in a high-concentration hydrochloric acid atmosphere.
[0016]
Therefore, first, the relationship between the decomposition rate of PCB and the reaction temperature of the supercritical water reaction was investigated in order to make the PCB content in the processing fluid produced by the supercritical water treatment of PCB be 3 ppb or less.
As a result, under the reaction pressure of 23 MPa and the reaction time of 2 minutes or more and 4 minutes or less, when the reaction temperature is 500 ° C., the PCB concentration is 3 ppb or more, and the discharge standard of 3 ppb cannot be satisfied. It was also found that the PCB concentration can be reduced to 3 ppb or less by setting the reaction temperature to 550 ° C. and 650 ° C. It was also found that when the reaction temperature was 500 ° C., the PCB concentration could not be reduced to 3 ppb or less even if the reaction time was 4 minutes or longer.
[0017]
That is, by setting the reaction temperature to a temperature in the range of 550 ° C. or more and 650 ° C. or less, the object to be treated contains an organic chlorine-based compound composed of PCB or a PCB-like compound so that the PCB concentration in the treatment fluid is 3 ppb or less. The liquid can be oxidatively decomposed by supercritical water reaction.
The PCB-like compound is a compound having a chemical structure almost similar to that of PCB, for example, dioxins, chlorobenzene compounds, chlorophenols, and the like.
[0018]
Next, in order to select a material that has corrosion resistance to high-concentration hydrochloric acid at a temperature of 550 ° C. or higher, a reactor is made of various materials, and the corrosion resistance of the material is evaluated by actually treating the PCB with supercritical water. A corrosion test was conducted.
By the way, for example, when PCBs having a purity of 100% from trichlorinated substances to pentachlorinated substances are treated with supercritical water, the concentration of hydrochloric acid produced is about 10% by mass to 15% by mass. Therefore, in the corrosion test, the hydrochloric acid concentration of the hydrochloric acid aqueous solution was 20% by mass, and the corrosion rates of various materials were measured as follows.
[0019]
First, autoclave-type reactors were prepared using the materials listed below, and an aqueous hydrochloric acid solution having a hydrochloric acid concentration of 20% by mass was accommodated in each reactor. The aqueous hydrochloric acid solution in the reactor was raised to an experimental temperature of 200 ° C. at a pressure of 22 MPa. Warmed and maintained at that temperature for 500 to 600 hours to measure the corrosion rate of the vessel walls of each reactor.
The results are as shown in Table 1. In Table 1, “-” indicates that the weight per unit area of the reactor increased due to the formation of chloride. Therefore, the corrosion rate indicated by minus means that the corrosion is in progress.
[Table 1]

[0020]
Next, when the experiment temperature was set in increments of 50 ° C. from 300 ° C. to 650 ° C. except for 550 ° C., the same corrosion experiment was performed, and the results of the corrosion experiments shown in Table 1 and FIG. 10 were obtained. FIG. 10 is a graph of the numbers in Table 1.
The materials used for the experiment have platinum (Pt), iridium (Ir), ruthenium (Ru), and rhodium (Rh) among the platinum group elements that are evaluated to have high corrosion resistance. Titanium {Ti (ASTM Grade 12)}, Tantalum (Ta), and Alumina oxide (Al₂O_Three).
[0021]
Since rhodium (Rh) is easily dissolved in an aqueous hydrochloric acid solution having a hydrochloric acid concentration of 20% by mass, it has been found that a reactor cannot be prepared and a corrosive experiment with the actual product cannot be performed. The test piece was immersed in an aqueous hydrochloric acid solution under the conditions to evaluate the corrosion resistance. The results of the rhodium corrosion experiment are shown in Table 1 as a corrosion rate of 27 mm / y at 300 ° C. Since rhodium dissolves in aqueous hydrochloric acid at 300 ° C, the dissolution rate is displayed as the corrosion rate. It is a thing.
[0022]
By the way, in the actual supercritical water treatment, if the corrosion rate of the reactor vessel wall is less than 1 mm / year, the corrosiveness is low, and it can be evaluated that it is the most preferable corrosion resistant material as the material of the reactor. Further, when the corrosion rate is 1 mm / year or more and less than 5 mm / year, the corrosion rate is corrosive within an acceptable range and can be evaluated as a corrosion-resistant material that can be used as a material for the reactor.
However, when the corrosion rate exceeds 5 mm / year, the corrosion rate exceeds an acceptable range, and cannot be evaluated as a corrosion-resistant material that can be adopted as a material for the reactor.
[0023]
According to the above-mentioned criteria for corrosion (corrosion resistance), whether or not each material subjected to the corrosion test can be used in the reactor was evaluated based on the corrosion rate of the vessel wall obtained in the corrosion test.
Materials other than iridium, namely titanium, tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), and alumina (Al₂O_ThreeThe corrosion rate of 1) is 1 mm / year or more and less than 5 mm / year in a specific temperature range and falls within an acceptable range, but the corrosion rate is high outside the temperature range and cannot be used as it is.
For example, titanium, ruthenium, and rhodium have a low corrosion rate in a high temperature region, but have a very high corrosion rate at a temperature of 400 ° C. or lower, particularly 300 ° C. Conversely, tantalum has a low corrosion rate in the temperature region of 400 ° C. or lower, but has a very high corrosion rate in the high temperature region of 400 ° C. or higher.
In addition, alumina oxide cannot be used as a corrosion-resistant material for a reactor because cracking occurs in a high temperature region, although the corrosion rate is low.
[0024]
Furthermore, even if it is a platinum group element evaluated as having high corrosion resistance, platinum, ruthenium (Ru), and rhodium (Rh) other than iridium have poor corrosion resistance except for a specific temperature range, and only iridium is present. Good corrosion resistance over a temperature range from room temperature to 650 ° C.
[0025]
The inside of the reactor is desired to be in a temperature range of 550 to 650 ° C. over the entire region, but in actual operation, when nozzle spraying deteriorates, a part of the reactor, particularly the lower part, has a temperature of 400 ° C. or less. In this range, the corrosion rate needs to be within an allowable range.
For example, in the case of a reactor using titanium, in order to make the corrosion resistance of titanium function, it is necessary to always maintain the reactor in a high temperature range, and a special temperature maintaining device is required. This increases the equipment cost and complicates the operation.
[0026]
From the above experimental results, the inventor considered combining titanium having good corrosion resistance in a temperature range of 400 ° C. or higher and tantalum having good corrosion resistance in a temperature range of 400 ° C. or lower.
By the way, titanium and tantalum have a problem that the temperature range in which the corrosion resistance is good is extremely critically limited, and if the temperature of the reaction vessel deviates from the temperature range showing the corrosion resistance for some reason, the corrosion progresses remarkably. On the other hand, iridium has good corrosion resistance over a temperature range from room temperature to 650 ° C., but has a problem that mechanical processing is difficult.
[0027]
Therefore, the present inventor, instead of forming an iridium layer by mechanical processing such as lining, uses an iridium oxide layer (IrO) by a chemical vapor deposition process (hereinafter referred to as a CVD method).₂) On the titanium or tantalum layer. When the corrosion resistance of the iridium oxide layer was examined in the same experiment as described above, it was confirmed by the experiment that it had the same corrosion resistance as the iridium layer.
The present inventor conducted experiments to grow an iridium oxide layer by a CVD method on a titanium layer or a tantalum layer, thereby combining a titanium layer and an iridium oxide layer, a tantalum layer and an iridium oxide layer. It was confirmed that a composite corrosion-resistant layer with three layers, or a composite corrosion-resistant layer of three layers of a tantalum layer, a titanium layer, and an iridium oxide layer can be formed.
[0028]
And Ti / IrO which laminated | stacked the iridium oxide layer with a film thickness of 2500-3000 nm on the titanium layer by CVD method₂The inner wall surface of the reactor was covered with a composite corrosion-resistant layer, and the same corrosion experiment as described above was performed.
As a result of the corrosion experiment, the corrosion rate was the same as that of iridium over the range from room temperature to 650 ° C., and was, for example, 300 ° C. plus 2 mm / year or less. That is, Ti / IrO₂The composite corrosion-resistant layer exhibits sufficient corrosion resistance even at a temperature of 400 ° C. or lower where the corrosion resistance of the titanium layer is low, and has almost the same corrosion resistance as iridium in the range from room temperature to 650 ° C.
[0029]
In addition, when forming the corrosion-resistant layer, the present inventor, rather than forming the corrosion-resistant layer with a single corrosion-resistant material, for example, an iridium layer, rather, a plurality of corrosion-resistant materials having slightly different corrosion resistance, for example, a titanium layer and iridium oxide. It was thought that the formation of a composite corrosion-resistant layer with the layer showed more reliable corrosion resistance even under unexpected conditions. For example, in the case of pitting corrosion, even if pitting corrosion occurs in the iridium oxide layer, pitting corrosion hardly progresses to the lower titanium layer. Further, even if an unexpected sudden temperature drop occurs in the reactor, if only the titanium layer is used, there is a concern about the occurrence and progression of corrosion, but since the iridium oxide layer is provided on the surface layer, corrosion does not occur.
Therefore, the present inventor coated the reaction vessel wall, which is easily corroded, with the above-mentioned composite corrosion-resistant layer, so that it can be safely performed within the allowable range of the corrosion rate, that is, over a long period of time, from normal temperature to 650 ° C. The present invention has been invented to enable supercritical water treatment of organochlorine compounds.
[0030]
  In order to achieve the above object, based on the above-mentioned knowledge, a supercritical water reactor according to the present invention (hereinafter referred to as the first invention) includes a reactor containing supercritical water, and includes an organic chlorine compound. In a supercritical water reactor in which a liquid to be treated containing is introduced into a reactor and oxidatively decomposed with an oxidizing agent,
  A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
  The reactor wall surface in contact with the liquid to be treated of the reactor was provided on the wall surface.A tantalum layer made of tantalum or a tantalum alloy, and provided on the tantalum layerA titanium layer made of titanium or a titanium alloy, and an iridium oxide layer laminated on the titanium layerThree layersIt is characterized by being coated with a composite corrosion-resistant layer.
[0031]
In the present invention, at least one of the flow rate of the liquid to be treated, the flow rate of the supercritical water, the flow rate of the makeup water to be fed to the reactor for generating supercritical water, and the temperature of the makeup water is selected. By adjusting and setting the reaction temperature to a temperature in the range of 550 ° C. or higher and 650 ° C. or lower, when the organochlorine compound is PCB or a PCB-like compound, PCB in the treatment liquid generated by oxidative decomposition of the liquid to be treated The concentration can be 3 ppb or less.
In the present invention, the PCB-like compound is a compound having a chemical structure almost the same as that of PCB, such as dioxins, chlorobenzene compounds, chlorophenols, and the like.
In the present invention, the wall surface of the reactor is coated with the specified composite corrosion-resistant layer, so even at the above-mentioned temperature, it is stable over a long period of time against the corrosive atmosphere caused by the generated hydrochloric acid, and an organic chlorine compound such as PCB can be used. The to-be-processed liquid containing can be processed.
The film thickness of the iridium oxide layer varies depending on the organochlorine compound to be treated and the hydrochloric acid concentration in the reactor, but is practically 1500 nm or more.
[0032]
  Main departureIn the lightThe reactor wall surface in contact with the liquid to be treated of the reactor has a tantalum layer made of tantalum or a tantalum alloy provided on the wall surface, a titanium layer made of titanium or a titanium alloy provided on the tantalum layer, and a titanium layer. It is covered with a three-layer composite anticorrosion layer with an iridium oxide layer laminated thereon.
  As a result, the iridium oxide layer corrodes, and even when the temperature of the reactor falls below 400 ° C. due to unforeseen circumstances and the titanium layer corrodes, corrosion resistance can be maintained in the inner tantalum layer. That is, it is based on the concept of fail-safe that is necessary when handling extremely harmful substances such as PCB.
  Further, a reactor wall surface in a region where the temperature calculated based on the temperature distribution in the reactor is less than 400 ° C., a tantalum layer made of tantalum or a tantalum alloy provided on the wall surface, and an oxidation layered on the tantalum layer. It is covered with a composite corrosion resistant layer with an iridium layer. Thereby, the corrosion resistance of the reactor can be further improved.
[0033]
  In the present invention, to coat with a composite corrosion resistant layer, first, a titanium layer is formed on a reactor wall formed of a nickel alloy or the like by a known lining method.,A tantalum layer is coated, and then an iridium oxide layer is grown on the titanium layer or the tantalum layer by a CVD method.
  Also, a titanium layer on the nickel alloy layer,The coated metal material coated with the tantalum layer is processed to form a reactor, and then an iridium oxide layer is grown on the titanium or tantalum layer on the reactor wall by a CVD method.
  In the present invention, the expression “coating the wall surface with a composite corrosion-resistant layer” includes a mode in which the reactor itself is formed of titanium or tantalum and an iridium oxide layer is laminated on the inner wall surface.
[0034]
Titanium and titanium alloy used in the present invention are defined by JIS standard or ASTM standard. For example, in JIS standard, pure titanium is a titanium metal defined by JIS type 1 to 3, and titanium alloy is titanium palladium. There are JIS 11 to 13 kinds of titanium alloys specified as alloys, and Ti-6Al-4V alloy and Ti-6Al-4VELI alloy as other titanium alloys.
In the ASTM standard, pure titanium is a titanium metal specified by ASTM Grade 1 to Grade 4, and the titanium alloy is a titanium alloy of ASTM Grade 7 and Grade 11 specified as a titanium palladium alloy. Also, Grade 12 or the like can be applied according to the ASTM standard.
[0035]
The tantalum and tantalum alloy used in the present invention are defined by JIS standard or ASTM standard, and besides tantalum, tantalum-tungsten alloy can be applied.
In the first invention, the titanium layer or titanium alloy layer and the tantalum layer or tantalum alloy layer may be lined on the vessel wall of the reactor or may be built up by a welding method. Moreover, it can also join to the container wall of a reactor by HIP process.
[0036]
  When the reactor is a pressure balance type reactor, the supercritical water reactor according to the present invention (hereinafter referred to as the second invention) includes a reactor containing supercritical water and contains an organic chlorine compound. In a supercritical water reactor in which a liquid to be treated is introduced into a reactor and oxidatively decomposed with an oxidizing agent,
  A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
  The reactor is a double cylinder of a pressure vessel and a reaction cartridge that communicates with the pressure vessel, and supplies a liquid to be treated and an oxidizing agent into the reaction cartridge, and the pressure vessel and the reaction cartridge Is configured as a pressure balance type reactor that supplies a pressure balance gas between the gas and the reaction cartridge to oxidatively decompose the liquid to be treated.
  At least the inner wall surface of the reaction cartridge has a tantalum layer made of tantalum or a tantalum alloy, a titanium layer made of titanium or a titanium alloy provided on the tantalum layer, and the titanium layer.It is characterized by being formed of a composite corrosion-resistant material comprising an iridium oxide layer laminated on the substrate.
[0037]
In the second invention, the temperature control device includes a feed flow rate of the liquid to be treated, a feed flow rate of supercritical water, a feed flow rate of makeup water to be fed to the reactor for generating supercritical water, and makeup water. By adjusting at least one of these temperatures, the temperature in the reactor can be controlled in the range of 550 ° C. or higher and 650 ° C. or lower.
[0038]
As another method, the reaction cartridge includes a tantalum layer made of tantalum or a tantalum alloy, a titanium layer made of titanium or a titanium alloy provided on both sides of the tantalum layer, and an iridium oxide layer laminated on both sides of the titanium layer. You may form with the composite corrosion-resistant material which consists of.
As a result, the iridium oxide layer corrodes, and even when the temperature of the reactor falls below 400 ° C. due to unforeseen circumstances and the titanium layer corrodes, corrosion resistance can be maintained in the inner tantalum layer.
[0039]
According to a third aspect of the present invention, there is provided a supercritical water reaction apparatus comprising a reactor containing supercritical water, wherein a liquid to be treated containing an organic chlorine compound is introduced into the reactor and oxidatively decomposed with an oxidizing agent.
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
The reactor is a double cylinder of a pressure vessel and a reaction cartridge that communicates with the pressure vessel, supplying the liquid to be treated and the oxidizing agent into the reaction cartridge, and the pressure vessel and the reaction cartridge It is configured as a pressure balance type reactor that supplies a gas for pressure balance between and oxidatively decomposes the liquid to be treated in the reaction cartridge,
A processing fluid flow path through which the processing fluid flows and an alkaline aqueous solution flow path that joins the processing fluid flow path and injects an alkaline aqueous solution into the processing liquid are provided to neutralize and rapidly cool the processing fluid to 450 ° C. or less with the aqueous alkaline solution. Equipped with a neutralization quenching section made outside the reactor,
The flow passage walls of the treatment fluid flow path and the alkaline aqueous solution flow path are covered with a composite corrosion-resistant layer of a tantalum layer made of tantalum or a tantalum alloy provided on the wall surface and an iridium oxide layer laminated on the tantalum layer. Yes.
In addition, the flow channel walls of the treatment fluid flow channel and the alkaline aqueous solution flow channel, a titanium layer made of titanium or a titanium alloy provided on the wall surface, a tantalum layer made of tantalum or a tantalum alloy provided on the titanium layer, You may make it coat | cover with a composite corrosion-resistant layer with the iridium oxide layer laminated | stacked on the tantalum layer.
The neutralization / quenching portion of the present invention is preferably used in combination with the first invention or the second invention.
[0040]
In the pressure balance type reactor, a neutralization quenching portion may be provided in an annular portion between the reactor pressure vessel and the reaction cartridge.
In the supercritical water apparatus according to the first and second inventions, the reactor forms only a supercritical water region over the entire region of the reactor, and does not form a subcritical water region.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below specifically and in detail with reference to the accompanying drawings.
Embodiment 1
This embodiment is an example of an embodiment of a supercritical water reactor according to the first invention. FIG. 1 is a flow sheet showing the configuration of the supercritical water reactor of this embodiment, and FIG. It is sectional drawing which shows the detail of a reactor.
The supercritical water reaction apparatus of the present embodiment is an apparatus for treating a liquid to be treated mainly containing PCB by supercritical water reaction in the presence of supercritical water, as shown in FIG. A vertical pressure-resistant sealed reactor 12 is provided as a reactor for performing the above-described processes. A cooler 16 for sequentially cooling the processing fluid is supplied to a processing fluid pipe 14 through which the processing fluid flows out of the reactor 12, and the pressure in the reactor 12. And a gas-liquid separator 20 for separating the processing fluid into gas and liquid.
[0042]
The supercritical water reactor 10 is a supply system for supplying a liquid to be processed for supercritical water reaction to a reactor 12. As a supply system, a liquid pump 24 to be processed whose discharge amount can be adjusted by inverter control or stroke control, and air compression. A treatment liquid containing PCB through the liquid pipe 22 to be treated, and air as an oxidant through the air feed pipe 26 and the liquid pipe 22 to be treated. To the reactor 12 together with the liquid to be treated.
Although not shown, supercritical water or makeup water for generating supercritical water may be supplemented to the reactor 12 as necessary, and a heater for heating the makeup water to a desired temperature may be provided. it can.
Further, the supercritical water reactor 10 includes a neutralization quenching section 30 in the processing fluid pipe 14 immediately after exiting the reactor 12, and an alkaline aqueous solution is injected into the processing fluid from the injection pipe 31 to bring the processing fluid to a temperature of 450 ° C. In the following, neutralization and quenching are preferably performed at 350 ° C. or lower.
[0043]
Further, the supercritical water reactor 10 includes a temperature control device 32 that controls the reaction temperature in the reactor 12 to, for example, 550 ° C. by adjusting the flow rate of the liquid to be treated. The temperature control device 32 has a thermometer 34 for measuring the temperature in the reactor 12, and adjusts the discharge amount of the liquid pump 24 to be processed based on the temperature of the thermometer 34 to adjust the outlet temperature of the liquid to be processed. Thus, the reaction temperature is controlled to a set temperature in the range of 550 ° C. or more and 650 ° C. or less.
The configuration of the temperature control device 32 is not limited to this. For example, by adjusting the flow rate of supercritical water, or by adjusting the flow rate of makeup water for generating supercritical water, the makeup water is further supplied. By adjusting the feed temperature, the reaction temperature in the reactor 12 can be controlled in the range of 550 ° C. or more and 650 ° C. or less.
[0044]
As shown in FIG. 2, the reactor 12 is formed as a vertical cylindrical container 12a having a mechanical strength that resists pressure during supercritical water treatment, for example, 23 MPa. The inner wall of the container 12a is covered with a composite corrosion resistant layer of a titanium layer 12b lined on the inner wall and an iridium oxide layer 12c grown on the titanium layer 12b by a CVD method.
[0045]
The growth process of the iridium oxide layer 12c by the CVD method is performed as follows, for example.
That is, the titanium layer is degreased with acetone in advance, and then oxidized in a steam stream at 700 ° C. to make the titanium layer surface into titanium oxide.
On the other hand, iridium chloride (IrC1_Three) Is dissolved in amyl alcohol, placed in a heating distillation apparatus equipped with a reflux condenser, and refluxing is continued at 90 ° C. for 10 hours, and iridium coating in which 3/4 of the iridium chloride chloride obtained is replaced with amyl alcohol. A liquid is produced.
This iridium coating solution is applied to the surface of the titanium oxide, naturally dried at room temperature, and then forcedly dried at 110 ° C.
Next, a thermal decomposition reaction treatment is performed for 10 minutes in a steam-containing atmosphere at 700 ° C. This coating → drying → pyrolysis reaction treatment was repeated 10 times to form an iridium oxide coating layer having an apparent film thickness of 3000 nm.
[0046]
  The reactor 12 is connected to the liquid pipe 22 to be processed, and has an inlet 36 through which the liquid to be processed and air flow into the reactor 12, and an outlet 38 through which the processing fluid flows out by connecting to the processing fluid pipe 14. Is provided on the side wall. The titanium layer 12bTheA laminated film of a titanium layer made of tantalum or a titanium alloy and a tantalum layer made of tantalum or a tantalum alloy provided between the titanium layer and the container wall.Ru.
[0047]
As shown in FIG. 3, the neutralization and quenching section 30 includes a processing fluid flow path 40 through which a processing fluid flows, and an alkaline aqueous solution flow in which an injection pipe 31 is joined to the processing fluid flow path 40 to inject an alkaline aqueous solution into the processing fluid. And a path 42. In the present embodiment, the processing fluid channel 40 and the alkaline aqueous solution channel 42 merge in a Y shape, but may merge at a right angle.
The processing fluid flow path 40 and the alkaline aqueous solution flow path 42 are each made of a tantalum tube wall 44 made of a tantalum alloy and a titanium tube made of titanium or a titanium alloy and provided on the inner periphery of the tantalum wall. It is formed with a three-layer structure of a wall 46 and an iridium oxide layer 47 grown on the titanium tube wall 46 by a CVD method. A nickel alloy steel pipe may be inserted into the outer periphery of the tantalum pipe wall 44, and the nickel alloy steel pipe may be used as the pressure structure.
[0048]
In order to form the neutralization and quenching portion 30, first, a tantalum alloy cylinder is formed, and then the cylinder is drilled to form a tantalum tube wall 44 having a through passage. Then, after a titanium alloy melt is poured into the through-passage of the tantalum tube wall 44 and allowed to cool and solidify, HIP treatment is performed to ensure the joining of the tantalum alloy phase and the titanium alloy phase.
Next, the titanium alloy phase is drilled to form a titanium tube wall 46 and a tantalum tube wall 44 provided outside the titanium tube wall 46. Subsequently, the treatment fluid channel 40 and the alkaline aqueous solution channel 42 can be formed by growing the iridium oxide layer 47 on the titanium tube wall 46 by the CVD method.
As another manufacturing method, a cylindrical body of tantalum alloy is formed, and then the cylindrical body is drilled to form a tantalum tube wall 44 having a through-passage, and the titanium alloy is welded onto the titanium tube wall 44 by a welding method or the like. The titanium wall 46 is provided by overlaying, and then an iridium oxide layer 47 is grown on the titanium tube wall 46 by a CVD method.
[0049]
As another method, the processing fluid channel 40 and the alkaline aqueous solution channel 42 of the neutralization quenching section 30 are grown on the tantalum tube wall made of pure tantalum or tantalum alloy and the tantalum tube wall by the CVD method, respectively. You may comprise from the made iridium oxide layer made.
In order to produce the neutralization quenching portion 30 of another method, for example, first, a tantalum alloy cylindrical body is formed, and then the cylindrical body is drilled to form a tantalum tube wall having a through passage. Next, an iridium oxide layer is grown on the tantalum tube wall surface by a CVD method.
[0050]
  In this embodiment, the temperature in the reactor 12 is controlled to 600 ° C. by the temperature control device 32, so that the liquid to be treated containing PCB is completely decomposed by supercritical water treatment, and the amount of PCB remaining in the treatment liquid Can be suppressed to 3 ppb or less.
  Further, the composite corrosion resistant layer of the titanium alloy layer 12b and the iridium oxide layer 12c functions reliably as the corrosion resistant layer of the reactor 12. Further, even if the temperature in the reactor 12 is lowered to 400 ° C. or lower, since the iridium oxide layer 12c is on the surface layer, corrosion does not proceed.
  The neutralization quenching section 30 is an iridium oxide layer47Therefore, corrosion does not occur. In the unlikely event, the iridium oxide layer47In the normal state where the temperature is high even if corrosion occurs, the titanium tube wall46Maintains the corrosion resistance, and conversely, in the state where the temperature is unexpectedly lowered to, for example, 400 ° C. or lower, the titanium tube wall46Is corroded, but the outer tantalum tube wall44Maintains corrosion resistance.
[0051]
Embodiment 2
This embodiment is an example of an embodiment of the supercritical water reactor according to the second invention, and FIG. 4 is a flow sheet showing the configuration of the supercritical water reactor of the present embodiment, FIG. ) Is a cross-sectional view showing details of the reactor, and FIG. 5 (b) is a cross-sectional view taken along line II in FIG. 5 (a) showing the structure of the composite corrosion-resistant material forming the reaction cartridge. 4 and 5, the same parts as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.
A supercritical water reactor 50 according to this embodiment is a supercritical water reactor equipped with a pressure balance type reactor composed of a pressure vessel and a reaction cartridge communicating with the reaction vessel as a reactor. 4 and FIG. 5, except that the configuration of the reactor 52, the neutralization quenching section is built in the reactor 52, and the pressure balance air is fed into the reactor 52. The configuration is the same as that of the first embodiment.
[0052]
As shown in FIG. 5A, the pressure balance type reactor 52 is a double cylinder body composed of a pressure vessel 54 provided as an outer cylinder and a reaction cartridge 56 provided as an inner cylinder in the pressure vessel 54. The interior 58 of the reaction cartridge 56 is formed as a reaction zone for supercritical water reaction.
The pressure vessel 54 is formed as a thick high-pressure steel pressure-resistant cylindrical vessel in order to counter the reaction pressure, and an annular portion 62 between the pressure vessel 54 and the reaction cartridge 56 is described later. It is an air layer as a gas for pressure balance and not a corrosive atmosphere.
On the other hand, as shown in FIG. 5 (b), the reaction cartridge 56 is formed as a thin, covered bottomed cylindrical body 56a formed of titanium or a titanium alloy, and further, the inner surface (inner 58) of the covered bottomed cylindrical body. The iridium oxide layer 56b grown by the CVD method is laminated on the side). It arrange | positions in the pressure vessel 54 so that it may have some clearance gap between the bottom part of the reaction cartridge 56, and the bottom part of the pressure vessel 54. FIG.
[0053]
An annular portion 62 that communicates with the inside of the reaction cartridge 56 through the communication hole 60 is formed between the pressure vessel 54 and the reaction cartridge 56, and has the same pressure as the air that flows into the reaction cartridge 56 through the nozzle 64. Since air is introduced into the annular portion 62, there is almost no pressure difference between the inside and outside of the reaction cartridge 56, and the pressure is balanced between the annular portion 62 and the inside of the reaction cartridge 56.
In other words, the pressure vessel 54 has a strength that resists the pressure at the time of supercritical water treatment, for example, 23 MPa, and the reaction cartridge 56 does not receive the internal pressure of the reactor 52 to divide the reaction zone. It functions as a sex barrier.
The reason why air is introduced into the annular portion 62 is that air is a non-corrosive fluid.
[0054]
The reactor 52 passes through the pressure vessel 54 and the reaction cartridge 56, and protrudes from the reaction cartridge 56 to the inside of the reaction cartridge 56. A fluid conduit 66, a neutralization quenching portion 68 provided in the processing fluid conduit 66 in the annular portion 62, and an air inlet nozzle 70 that sends air to the annular portion 62 as a pressure balance gas are provided.
The neutralization and quenching section 68 has the same structure as that of the neutralization and quenching section 30 of Embodiment 1 (see FIG. 3). The injection pipe 31 is connected, and an alkaline aqueous solution is injected into the processing fluid. It is designed to cool quickly.
The nozzle 64 is connected to the liquid pipe 22 (see FIG. 4), and the processing fluid conduit 66 is connected to the processing fluid pipe 14. The air feed nozzle 70 is connected to an air feed branch pipe 72 (see FIG. 4) branched from the air feed pipe 26, introduces air into the annular portion 62, and then passes through the communication hole 60 to react cartridge. 56 is allowed to flow into the interior of the oxidizer.
[0055]
In the present embodiment example, similarly to the first embodiment example, the temperature control device 32 controls the temperature in the reactor 52, more precisely, the reaction cartridge 56 to, for example, 600 ° C. By completely decomposing by the critical water treatment, the amount of PCB remaining in the treatment liquid can be suppressed to 3 ppb or less.
Further, since the temperature in the reactor 12 is controlled at 600 ° C., the reaction cartridge 56 formed of a titanium alloy and further coated with an iridium oxide layer functions reliably as a corrosion-resistant wall that secures a reaction zone. The neutralization quenching portion 68 also functions in the same manner as the first embodiment and has the same effect.
[0056]
Embodiment 3
This embodiment is an example of an embodiment of a supercritical water reactor according to the second invention, and FIG. 6A is a cross-sectional view showing details of the reactor of Embodiment 3, FIG. FIG. 6A is a cross-sectional view taken along line II in FIG. 6A, and FIG. 6C is a composite corrosion-resistant material forming the inner cylinder of the reaction cartridge. FIG. 7 is a cross-sectional view taken along line II-II in FIG. In FIG. 6, the same parts and components as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted.
The supercritical water reactor according to the present embodiment has the same configuration as that of Embodiment 2 except that the reactor 76 is different from the reactor 52 and has an inner cylinder in the reaction cartridge.
[0057]
As shown in FIG. 6A, the reactor 76 is a pressure balance type reactor including a pressure vessel 54 and a reaction cartridge 80 communicating with the pressure vessel 54. The reaction cartridge 80 includes an outer cylinder 82. And an inner cylinder 84 housed in the outer cylinder 82 and having a reaction zone for supercritical water reaction inside.
The outer cylinder 82 is formed as a bottomed covered cylindrical body 82a made of titanium or a titanium alloy as shown in FIG. 6B, as in the reaction cartridge 56 of the second embodiment, and further, the inner surface of the cylindrical body 82a. Is covered with an iridium oxide layer 82b grown by the CVD method.
The inner cylinder 84 is formed as a bottomed cylindrical body 84a made of titanium or titanium alloy having an open upper end and an inverted conical bottom, and the inner and outer surfaces of the cylindrical body 84a are formed as shown in FIG. The iridium oxide layer 84b is grown by the CVD method.
In addition, the inner cylinder 84 is not limited to this shape, such as a shape of an umbrella upside down, as long as it can be directed upward by reversing the flow of fluid ejected from the nozzle and directed downward, There is no restriction on its shape.
[0058]
The liquid to be treated that flows in from the nozzle 64 is supercritical water treated inside the inner cylinder 84 and flows into the annular portion 86 between the outer cylinder 82 and the inner cylinder 84 from the upper end opening as a processing fluid. The portion 86 flows down, enters the bottom of the outer cylinder 82, and flows out to the processing fluid pipe 14 through the processing liquid conduit 88 connected to the bottom of the outer cylinder 82.
The processing fluid conduit 88 in the pressure vessel 54 is provided with a neutralization and quenching unit 90 having the same structure as that of the neutralization and quenching unit 30 of the first embodiment (see FIG. 3). An alkaline aqueous solution is poured into the liquid and neutralized and rapidly cooled to 450 ° C. or lower.
The air feeding nozzle 70 introduces air into the annular portion 62, and then flows into the reaction cartridge 80 from the upper end opening of the reaction cartridge 80 through the communication hole 60 to form a part of the oxidizing agent.
With the above configuration, the supercritical water reactor according to the present embodiment also has the same effect as the second embodiment.
[0059]
Embodiment 4
This embodiment is an example of an embodiment of a supercritical water reactor according to the second invention, and FIG. 7 is a sectional view showing details of the reactor. In FIG. 7, the same parts and components as those in FIG.
The supercritical water reactor according to the present embodiment is different from that according to the third embodiment except that the neutralization quenching section 92 is provided outside the reactor and the configuration of the reactor 94 is different in relation thereto. Have the same configuration.
As shown in FIG. 7, the reactor 94 has the same configuration as that of the reactor 76 in the third embodiment except that a neutralization quenching section 92 is provided outside the reactor, and the outer cylinder of the reaction cartridge. 82 is in contact with the bottom of the pressure vessel 54, and the processing fluid pipe 14 passes through the bottom of the pressure vessel 54 and communicates with the inside of the outer cylinder 82.
The neutralization quenching section 92 is provided in the processing fluid pipe 14 so as to be in contact with the bottom of the pressure vessel 54.
In the reactor 94 of the present embodiment example, the neutralization quenching section 92 can be easily attached as compared with the reactor 76 of the third embodiment example.
In the reactor 52 of the supercritical water reactor according to the second embodiment, the bottom of the reaction cartridge 56 is disposed on the bottom of the pressure vessel 54, and instead of the neutralization quenching section 68 provided in the annular section 62, FIG. 7, the neutralization quenching section 92 can be provided so as to be in contact with the bottom of the pressure vessel 54.
[0060]
【The invention's effect】
According to the present invention, by controlling the reaction temperature in the range of 550 ° C. or more and 650 ° C. or less, the liquid to be treated containing the organic chlorine compound can be rendered detoxified by supercritical water treatment, for example, PCB or PCB In the case of a similar compound or the like, the PCB concentration in the processing fluid can be 3 ppb or less.
Further, according to the present invention, the progress of corrosion of the reactor is suppressed by coating the reactor wall or the reaction cartridge with the composite corrosion-resistant layer that specifies or the composite corrosion-resistant material that specifies the organic chlorine compound. For example, to realize a supercritical water reactor that stably treats a liquid to be treated containing PCB or a PCB-like compound with a supercritical water treatment to reduce the PCB concentration in the treatment fluid to 3 ppb or less over a long period of time. ing.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing a configuration of a supercritical water reactor according to Embodiment 1;
FIG. 2 is a cross-sectional view showing details of a reactor according to Embodiment 1;
FIG. 3 is a cross-sectional view of a neutralization quenching portion.
4 is a flow sheet showing a configuration of a supercritical water reactor according to Embodiment 2. FIG.
5A is a cross-sectional view showing details of the reactor of Embodiment 2, and FIG. 5B is a line of FIG. 5A showing the structure of the composite corrosion-resistant material forming the reaction cartridge. It is sectional drawing of II.
6A is a cross-sectional view showing details of the reactor according to Embodiment 3, and FIG. 6B shows the structure of a composite corrosion-resistant material that forms the outer cylinder of the reaction cartridge. ) Of FIG. 6A is a cross-sectional view taken along line II of FIG. 6A, and FIG. 6C is a cross-sectional view taken along line II-II of FIG.
FIG. 7 is a cross-sectional view showing details of a reactor according to Embodiment 4;
FIG. 8 is a flow sheet showing the configuration of a conventional supercritical water reactor.
FIG. 9 is a cross-sectional view showing a configuration of a conventional pressure balanced reactor.
FIG. 10 is a graph showing the results of a corrosion experiment.
[Explanation of symbols]
10 Supercritical water reactor according to Embodiment 1
12 Reactor
12a Vertical cylindrical container
12b Titanium alloy layer
12c Iridium oxide layer
14 Processing fluid pipe
16 Cooler
18 Pressure control valve
20 Gas-liquid separator
22 Liquid tube to be treated
24 Liquid pump to be treated
26 Air inlet pipe
28 Air compressor
30 Neutralization and quenching section
31 Injection tube
32 Temperature controller
34 Thermometer
36 Inlet
38 outlet
40 Processing fluid flow path
42 Alkaline aqueous solution flow path
44 Tantalum tube wall
46 Titanium tube wall
47 Iridium oxide layer
50 Supercritical water reactor according to Embodiment 2
52 reactor
54 Pressure vessel
56 reaction cartridges
56a Thin, covered, bottomed cylindrical body formed of titanium or a titanium alloy
56b Iridium oxide layer
58 Inside the reaction cartridge
60 communication hole
62 Annular part
64 nozzles
66 Processing Fluid Conduit
68 Neutralization and quenching section
70 Air feed nozzle
72 Air supply branch pipe
76 Reactor of Embodiment 3
80 reaction cartridge
82 outer cylinder
82a Bottomed and covered cylinder made of titanium or titanium alloy
82b Iridium oxide layer
84 Inner cylinder
84a Bottomed cylindrical body made of titanium or titanium alloy
84b Iridium oxide layer
86 Annular part
88 Processing fluid conduit
90 Neutralization and quenching section
92 Neutralization quenching part of Embodiment 4
94 Reactor of Embodiment 4
100 Conventional supercritical water reactor
102 reactor
104 Supercritical water region
106 Virtual interface
108 Subcritical water region
110 Inflow pipe
112 Liquid line to be treated
114 air line
115 Supercritical water line
116 Neutralizer line
118 Processing fluid line
120 Subcritical water line
122 Subcritical drainage line
130 Pressure balance reactor
131 Outer cylinder
132 reaction cartridge
133 Inlet nozzle
134 reaction zone
135 Gas inlet for pressure balance
136 Annular part
137 Upper gap
138 Reactor outlet tube

Claims (7)

In a supercritical water reactor equipped with a reactor containing supercritical water, introducing a liquid to be treated containing an organic chlorine compound into the reactor and oxidatively decomposing with an oxidant,
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
The reactor wall surface in contact with the liquid to be treated of the reactor is formed on a tantalum layer made of tantalum or a tantalum alloy provided on the wall surface, a titanium layer made of titanium or a titanium alloy provided on the tantalum layer, and the titanium layer. A supercritical water reactor characterized in that it is covered with a three-layer composite anticorrosion layer with a laminated iridium oxide layer. In a supercritical water reactor equipped with a reactor containing supercritical water, introducing a liquid to be treated containing an organic chlorine compound into the reactor and oxidatively decomposing with an oxidant,
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
A reactor wall surface in a region where the temperature calculated based on the temperature distribution in the reactor is less than 400 ° C., a tantalum layer made of tantalum or a tantalum alloy provided on the wall surface, and an iridium oxide layer laminated on the tantalum layer supercritical water reactor you characterized in that it is coated with a composite corrosion resistant layer with. In a supercritical water reactor equipped with a reactor containing supercritical water, introducing a liquid to be treated containing an organic chlorine compound into the reactor and oxidatively decomposing with an oxidant,
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
The reactor is a double cylinder of a pressure vessel and a reaction cartridge that communicates with the pressure vessel, and supplies a liquid to be treated and an oxidizing agent into the reaction cartridge, and the pressure vessel and the reaction cartridge Is configured as a pressure balance type reactor that supplies a pressure balance gas between the gas and the reaction cartridge to oxidatively decompose the liquid to be treated.
At least the inner wall surface of the reaction cartridge is composed of a tantalum layer made of tantalum or a tantalum alloy , a titanium layer made of titanium or a titanium alloy provided on the tantalum layer, and an iridium oxide layer laminated on the titanium layer. A supercritical water reactor characterized by being made of food. In a supercritical water reactor equipped with a reactor containing supercritical water, introducing a liquid to be treated containing an organic chlorine compound into the reactor and oxidatively decomposing with an oxidant,
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
A processing fluid flow path through which the processing fluid flows and an alkaline aqueous solution flow path that joins the processing fluid flow path and injects the alkaline aqueous solution into the processing fluid are provided, and the processing liquid is neutralized and rapidly cooled to 450 ° C. or less by the alkaline aqueous solution. Equipped with a neutralization quenching section made outside the reactor,
The flow passage walls of the treatment fluid flow path and the alkaline aqueous solution flow path are covered with a composite corrosion-resistant layer of a tantalum layer made of tantalum or a tantalum alloy provided on the wall surface and an iridium oxide layer laminated on the tantalum layer. A supercritical water reaction apparatus characterized by comprising: In a supercritical water reactor equipped with a reactor containing supercritical water, introducing a liquid to be treated containing an organic chlorine compound into the reactor and oxidatively decomposing with an oxidant,
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
A processing fluid flow path through which the processing fluid flows and an alkaline aqueous solution flow path that joins the processing fluid flow path and injects the alkaline aqueous solution into the processing fluid are provided, and the processing liquid is neutralized and rapidly cooled to 450 ° C. or less by the alkaline aqueous solution. Equipped with a neutralization quenching section made outside the reactor,
Titanium layer made of titanium or a titanium alloy provided on the wall surface, and a tantalum layer made of tantalum or a tantalum alloy provided on the titanium layer, and a tantalum layer. A supercritical water reactor characterized in that it is coated with a composite corrosion-resistant layer with an iridium oxide layer laminated thereon. In a supercritical water reactor equipped with a reactor containing supercritical water, introducing a liquid to be treated containing an organic chlorine compound into the reactor and oxidatively decomposing with an oxidant,
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
The reactor is a double cylinder of a pressure vessel and a reaction cartridge that communicates with the pressure vessel, supplying the liquid to be treated and the oxidizing agent into the reaction cartridge, and the pressure vessel and the reaction cartridge It is configured as a pressure balance type reactor that supplies a gas for pressure balance between and oxidatively decomposes the liquid to be treated in the reaction cartridge,
A processing fluid channel through which the processing fluid flows and an alkaline aqueous solution channel that joins the processing fluid channel and injects an alkaline aqueous solution into the processing fluid are provided, and the processing solution is neutralized and rapidly cooled to 450 ° C. or less by the alkaline aqueous solution. The neutralization quenching section is provided in the annular section between the pressure vessel of the reactor and the reaction cartridge,
The flow passage walls of the treatment fluid flow path and the alkaline aqueous solution flow path are covered with a composite corrosion-resistant layer of a tantalum layer made of tantalum or a tantalum alloy provided on the wall surface and an iridium oxide layer laminated on the tantalum layer. A supercritical water reaction apparatus characterized by comprising: In a supercritical water reactor equipped with a reactor containing supercritical water, introducing a liquid to be treated containing an organic chlorine compound into the reactor and oxidatively decomposing with an oxidant,
A temperature control device for controlling the temperature in the reactor in a range of 550 ° C. or higher and 650 ° C. or lower;
The reactor is a double cylinder of a pressure vessel and a reaction cartridge that communicates with the pressure vessel, supplying the liquid to be treated and the oxidizing agent into the reaction cartridge, and the pressure vessel and the reaction cartridge It is configured as a pressure balance type reactor that supplies a gas for pressure balance between and oxidatively decomposes the liquid to be treated in the reaction cartridge,
A processing fluid channel through which the processing fluid flows and an alkaline aqueous solution channel that joins the processing fluid channel and injects an alkaline aqueous solution into the processing fluid are provided, and the processing solution is neutralized and rapidly cooled to 450 ° C. or less by the alkaline aqueous solution. The neutralization quenching section is provided in the annular section between the pressure vessel of the reactor and the reaction cartridge,
Titanium layer made of titanium or a titanium alloy provided on the wall surface, and a tantalum layer made of tantalum or a tantalum alloy provided on the titanium layer, and a tantalum layer. A supercritical water reactor characterized in that it is coated with a composite corrosion-resistant layer with an iridium oxide layer laminated thereon.

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