JP3822093B2

JP3822093B2 - Apparatus and method for purifying polluted air by photolysis

Info

Publication number: JP3822093B2
Application number: JP2001339572A
Authority: JP
Inventors: 幸道東; 知人東; 由起子秋山
Original assignee: 株式会社東エンジニアリング
Priority date: 2001-11-05
Filing date: 2001-11-05
Publication date: 2006-09-13
Anticipated expiration: 2021-11-05
Also published as: JP2003135576A

Description

【０００１】
【発明の属する技術分野】
本発明は空気中に含まれる汚染物質を光分解する空気の浄化装置及びその方法に関する。より詳細には、本発明は、空気中に含まれるアンモニア、アミン、メルカプタン、有機塩素化合物等の汚染物質を光触媒と紫外線照射との作用により、酸化分解する汚染空気の浄化装置及びその方法に関する。
【０００２】
【従来の技術】
生ゴミ処理場や産業廃棄物処理場から発生するアンモニア、アミン、メルカプタン等の悪臭成分は、処理場周囲の住民に不快感を懐かさせ、長年にわたって公害問題となっている。また、従来からトリクロロエチレン、テトラクロロエチレン等の有機塩素化合物がドライクリーニング工場、金属の脱脂処理、基板の洗浄工程等に大量に使用されてきたが、その一部が地下に染み込み、更に地下水に混入している事実が報告され、健康上不安視されている。地下水に含まれる揮発性有機塩素化合物の除去方法として、本出願人は、適宜の手段により有機塩素化合物を気化させた後、これを分解処理する方法を提案している（特願２００１−２３８７８５号）。
空気中に含まれる有機塩素化合物の一般的な除去方法としては、例えば活性炭等の吸着剤に吸着させる方法、加熱下に触媒と接触させて分解する方法、プラズマ放電による方法等が知られている。しかしながら、吸着方法では吸着剤の後処理が必要であり、接触分解方法では触媒を加熱するためにかなりのエネルギーが必要であり、また、プラズマ放電法では多大の電力を必要とするという問題があった。
【０００３】
近年、光触媒と紫外線照射とを組み合わせて有機物質を酸化分解する光分解技術が開発され、これを有機塩素化合物の除去方法に利用した提案が数多くなされている。そのうちの２，３の例を挙げてみると、次のようなものがある。
例えば、排ガスとの接触面となる管壁等に光触媒膜を固定し、この光触媒膜に紫外線を照射して有機塩素化合物を分解する方法が提案されている。しかし、この方法は、光触媒膜の表面積が小さく、分解効率がよくないという問題がある。排ガスとの接触面積を増大させるために、光触媒をハニカム構造とすることも考えられるが、その場合には光触媒膜の奥部まで紫外線を照射させることが困難であり、やはり分解効率の向上が望めないと考えられる。
【０００４】
また、排ガス中に光触媒粉末を吹き込んで有機塩素化合物を吸着させて、集塵部においてバグフィルターにより仕切られた空間に設置された紫外線ランプにより、光触媒に紫外線を照射して有機塩素化合物を分解する方法が提案されている（特開平１０−３２８５３号公報）。しかし、この方法は、光分解装置内部に紫外線ランプ（紫外線照射源）を設置する必要があるために、照射源の汚れ等によって紫外線の照射強度が低下して、分解効率の悪化が避けられないという問題がある。
更に、粒状の光触媒担体を用い、被処理排ガスの送風及び被処理水の送水による攪拌で、光触媒担体を流動させながら有機塩素化合物を分解する方法が提案されている（特開２００１−７９３５１号公報、特開２００１−１９１０６７号公報）。しかし、この方法は、光触媒担体の流動性がさほど良好でないので、極く微量の薄膜濃度の有機塩素化合物が光触媒担体に吸着されず、ショートパスして未処理のまま反応装置の系外に放出される可能性がある。
【０００５】
【発明が解決しようとする課題】
このように、光触媒と紫外線照射との組み合わせによる有機物質の分解除去方法においては、紫外線照射源からの照射強度が次第に低下して汚染物質の分解効率が悪化し、また、極く低濃度の汚染物質（有機塩素化合物）を分解除去する場合には汚染物質が光触媒に充分に吸着されないという問題があった。
そこで、本発明の目的は、上述の従来技術の問題点を解消することにあり、紫外線照射源から紫外線を光触媒に充分に照射することができ、空気中の汚染物質の濃度がたとえ数百ｐｐｂ程度の極く低濃度であっても、汚染物質が未処理のまま装置の系外に放出されることを防止することが可能で、汚染物質の分解効率に優れた光分解による汚染空気の浄化装置及びその方法を提供することにある。
【０００６】
【課題を解決するための手段】
本発明者らは、上述の従来技術の問題点を解決すべく、鋭意検討を重ねてきたところ、複数段の光酸化反応室及び活性炭充填層を形成した空気浄化装置において、光透過性の垂直透明板と傾斜透明板とから構成される三角形状の紫外線照射室を各光酸化反応室内に形成することにより、光酸化反応室に充填された光触媒が良好な循環状態に保たれ、この流動状態にある光触媒に紫外線を充分に照射できる結果、汚染物質を効率よく分解することを見い出して、本発明をなすに至った。
【０００７】
即ち、本発明の光分解による汚染空気の浄化装置は、装置本体の下方及び上方にそれぞれ空気流入口及び空気排出口が設けられ、装置本体内の下部に複数段の光酸化反応室が形成され、その上部に活性炭充填層が形成され、各光酸化反応室のそれぞれの上部と底部及び活性炭充填層が多数の通気孔を有する仕切板で仕切られた光分解による汚染空気の浄化装置において、各光酸化反応室の内部には、光透過性の垂直透明板と傾斜透明板と前記光酸化反応室底部の仕切板とから構成される縦断面形状が実質的に三角形の紫外線照射室を形成すると共に、紫外線照射室の内部には紫外線照射源が配置され、紫外線照射室を除く光酸化反応室の内部には部分的に粒状の光触媒が充填され、また、上記活性炭充填層内には粒状の活性炭が充填されていることを特徴とする。
【０００８】
また、本発明の光分解による汚染空気の浄化方法は、多数の通気孔を有する装置本体底部の仕切板を介して汚染物質を含む空気を最下段の光酸化反応室に導入し、複数段の光酸化反応室内で光触媒と紫外線照射との作用により汚染物質を酸化分解しつつ、最上段の光酸化反応室を経た空気に含まれる未分解の汚染物質を活性炭充填層内に充填された粒状の活性炭に吸着させた後、浄化された空気を装置本体から放出する光分解による汚染空気の浄化方法において、各光酸化反応室の内部には、光透過性の垂直透明板と傾斜透明板と前記光酸化反応室底部の仕切板とから構成される縦断面形状が実質的に三角形の紫外線照射室が形成され、紫外線照射室を除く光酸化反応室の空間に部分的に充填された粒状の光触媒を下方から上昇する空気流により流動化させながら、紫外線照射室に配置された紫外線照射源から汚染物質が吸着された光触媒に紫外線を照射して、空気中の汚染物質を酸化分解することを特徴とする。
【０００９】
【作用】
本発明の光分解による汚染空気の浄化装置は、上記した通り、多数の通気孔を有する仕切板でそれぞれ仕切られた複数の光酸化反応室及び活性炭充填層からなり、光透過性の垂直透明板と傾斜透明板とから構成される三角形状の紫外線照射室を各光酸化反応室内に形成したものである。
また、本発明の汚染空気の浄化方法は、複数の光酸化反応室内で光触媒と紫外線照射との作用により汚染物質を酸化分解しながら、未分解の汚染物質を活性炭に吸着させる方法からなり、上昇空気流により流動化される光触媒に上記紫外線照射室から紫外線を照射するものである。
【００１０】
そのため、光酸化反応室の底部堆積部で汚染物質がまず粒状の光触媒に確実に吸着される。しかも、垂直透明板及び傾斜透明板に沿って上昇する空気流によって、光触媒が吹き上げられかつ上方で拡散され、飛散状態の光触媒部分に紫外線が効率よく照射されるので、光触媒に吸着された汚染物質を効率よく酸化分解することができる。更に、傾斜透明板に沿って光触媒が落下して底部仕切板に光触媒が堆積するように、底部仕切板と傾斜透明板とから流動床が構成されるので、光触媒は光酸化反応室内で良好な循環状態が保たれる。
また、本発明の汚染空気の浄化装置及び方法は、上述の構造からなる複数段の光酸化反応室とその上方に活性炭充填層が配置されている。そのため、光酸化反応室において汚染物質のショートパスが回避され、最上段の光酸化反応室を経た空気に含まれる分解されなかった汚染物質は活性炭充填層内に充填された粒状の活性炭に吸着されるので、汚染物質が未処理のまま浄化装置の系外に放出されるのを防止することができる。
【００１１】
【発明の実施の形態】
次に、本発明を詳細に説明する。
本発明により処理される汚染物質としては、極く低濃度でも健康上有害なあるいは悪臭を放つ揮発性の物質であれば特に限定されるものではないが、例えば、トリクロロエチレン、テトラクロロエチレン、トリクロロエタン等の有機塩素系溶剤の他に、アンモニア、トリメチルアミン等のアミン、硫化水素、硫化メチル等のメルカプタン、ホルムアルデヒドなどの臭気物質が挙げられる。
本発明の光分解による汚染空気の浄化装置及びその方法は、前述の通り、装置本体内の下部に複数段の光酸化反応室が形成され、その上部に活性炭充填層が形成されている。各光酸化反応室及び活性炭充填層は、装置本体下方から導入される汚染物質を含む空気が通気でき、浄化された空気が装置本体上方から放出されるよう、多数の通気孔を有する底部及び上部仕切板で仕切られている。仕切板としては、金網や、円形、楕円形、角形、星形等の細孔が穿設されたパンチングメタルが好ましく用いられる。網目または細孔の大きさは、粒状の光触媒または活性炭が仕切板から抜け落ちない程度のものであればよい。
【００１２】
光酸化反応室は、空気中に含まれる汚染物質の濃度、単位時間当たりの風量、光触媒の充填量、汚染物質の分解効率等を予め考慮に入れて、汚染物質がショートパスしないように適宜段数を増加することができる。
各光酸化反応室内には、上記底部仕切板と共に光透過性の垂直透明板と傾斜透明板とから構成される紫外線照射室が形成されている。紫外線照射室を形成する仕切板部分は、稼働中に発生する微粉状の光触媒が紫外線照射室に混入しないよう、網目または細孔を塞ぐか予め細孔を穿設していない板状部材とすることが好ましい。また、光酸化反応室の装置本体側壁と傾斜透明板とを組み合わせて、紫外線照射室を更に形成してもよい。このようにして、１つの光酸化反応室内には通常複数の紫外線照射室が形成され、各紫外線照射室の内部には１つまたは複数の紫外線照射源が配設される。
【００１３】
紫外線照射室はその縦断面形状が実質的に三角形をなしており、底部仕切板に対する紫外線照射室側に傾斜する傾斜透明板の傾斜角度が５０〜７０°の範囲にあることが好ましい。
上記傾斜角度は、５５〜６５°の範囲がより好ましく、５７〜６３°の範囲にあることが特に好ましい。傾斜角度が５０°未満であると、下方から空気を流入する仕切板の全開口面積が小さく、光触媒の流動性が低下する。一方、上記角度が７０°より大きくなると、流入する空気が光酸化反応室の上部でさほど拡散されず、光触媒の流動化による汚染物質の酸化分解効率が低下する。のみならず、紫外線照射室のスペースが小さく、その内部に配置される紫外線照射源の保守点検作業が困難となる。
【００１４】
前記底部仕切板と上部仕切板との間に垂直透明板及び傾斜透明板を配置して、両透明板が当接する紫外線照射室の上端部と上部仕切板との間に間隙を設けないことが好ましい。これにより、光酸化反応室の１つの空間に充填された光触媒が他方の空間に移動することがないので、長期間にわたって汚染物質を安定して酸化分解することができる。
垂直透明板及び傾斜透明板は、ガラスやポリメタクリル酸メチル等の光透過性、即ち紫外線透過性に優れた材質のものが用いられる。紫外線照射源としては、波長３９０ｎｍ以下の紫外線を照射する紫外線ランプが通常使用される。また、光酸化反応室特に紫外線照射室を構成する装置本体内壁の表面、更には底部仕切板表面に、反射性薄膜を蒸着するかあるいは反射板を張設して、これらの表面を反射面（以下、反射板で代表する）とすることもできる。その場合、紫外線照射源から照射される紫外線は、例えば粗面加工された反射板等で乱反射されることが好ましく、光酸化分解作用が更に増強される。
【００１５】
紫外線照射室を除く光酸化反応室の内部には、粒状形態の光触媒が部分的に充填される。光触媒としては、酸化チタン、酸化亜鉛、酸化タングステン等が挙げられる。これらの光触媒は、ゼオライト、シリカゲル、アルミナ、多孔質ガラス等の粒状多孔質担体の表面及び内部に担持されるている。光触媒担体の粒径は、１．５〜１０mmの範囲にあり、２〜４mmの範囲にあることが好ましい。また、紫外線照射室を除く光酸化反応室に対する光触媒の見掛け充填率は、２０〜７０容量％の範囲にあることが好ましい。
光触媒の粒径が１．５mm未満であると、底部及び上部仕切板の網目または細孔を光触媒担体の粒径より小さくする必要があり、仕切板の単位面積当たりの開口面積が小さいため、例えば送風機により下方から送気される空気に対する仕切板の抵抗が大きくなる。一方、粒径が１０mmより大きいと、光触媒の流動性が低下する。上記充填率が２０容量％未満であると、紫外線照射室を除く光酸化反応室の単位体積当たりの汚染物質の酸化分解効率を充分に確保することができない。一方、充填率が７０容量％より大きいと、光触媒の流動性が低下し、光触媒が光酸化反応室内で充分に循環しない。
【００１６】
上記活性炭充填層内には、炭素質を賦活して成形された粒状の活性炭が充填される。活性炭充填層は複数層に適宜分割することもできる。また、活性炭を必ずしも充填層内全体に充填する必要はない。
活性炭充填層内には、汚染空気に含まれる汚染物質の性状に応じて、塩基性ガス用、中性ガス用及び酸性ガス用の活性炭を単独または混合して充填することが好ましい。例えば、処理対象汚染物質が有機塩素化合物である場合、空気が光触媒を通過する際に、ＨＣｌとＣＯ₂とＨ₂Ｏに分解され、処理空気が酸性ガスを含有する傾向にある。その場合には、酸性ガス吸着用に塩基性に改質された粒状活性炭を充填することが好ましい。
活性炭の粒径は２〜６mmの範囲にある。活性炭の粒径が２mm未満であると、活性炭充填層を通過する空気の抵抗が大きくなる。一方、粒径が６mmより大きいと、単位体積当たりの活性炭の表面積が小さくなり、汚染物質の吸着効率が低下するので好ましくない。
【００１７】
更に、最下段の光酸化反応室の下方に空気溜りを形成して、光触媒が充填された光酸化反応室に流入する空気の流速を均一化することが好ましい。同様に、下方に位置する光酸化反応室の上部仕切板とその上方に位置する光酸化反応室の底部仕切板との間、及び最上段の光酸化反応室の上部仕切板と活性炭充填層の底部仕切板との間に、それぞれ空気溜りを形成することが好ましい。
これらの空気溜りの少なくとも１つを形成しておくと、光触媒及び／又は活性炭への汚染物質の吸着ムラが少なくなる。例えば、異なる光酸化反応室の仕切板間に空気溜りを形成した場合、光触媒がほぼ均一に流動・循環するようになり、汚染物質の酸化分解効率が向上する。
【００１８】
【実施例】
以下、図面を参照しながら本発明を更に具体的に説明する。
図１において、１は外形が概略正四角形の塔から形成された空気浄化装置本体であり、装置本体１の底部にはこれを支持する４本の脚２が取り付けられている。また、装置本体１の下部は上方に拡径する下部空気溜り３が形成され、その下方中央に下部空気溜り３に連通する空気流入口４が形成されると共に、その後方に送風機（図示せず）が配置されている。
装置本体１内には、１０メッシュの金網からなる第一底部仕切板５ａと、これと所定の間隔を介して、仕切板５ａと同様の金網からなる第一上部仕切板５ｂとで仕切られた光酸化反応室６及びその上方の中間空気溜り７が、複数段形成されている。図１では、光酸化反応室６及び中間空気溜り７が２段形成された例を示している。
【００１９】
光酸化反応室６の第一仕切板５ａ，５ｂ間には、光透過性のガラスからなる複数枚の垂直透明板８及び傾斜透明板９が配置され、透明板８，９及び底部仕切板５ａで区画された空間を紫外線照射室１０としている。なお、紫外線照射室１０を構成する仕切板５ａ部分は反射板１１で閉塞されている。透明板８，９は上端部が傾斜角３０°で当接している（従って、底部仕切板５ａに対する傾斜透明板９の傾斜角度は６０°となる）。また、紫外線照射室１０の内部には、近紫外線を照射する紫外線ランプ１２が配設されている。
図１では、３枚の傾斜透明板９と反射板１１と２枚の垂直透明板８及び装置本体１内壁面の反射板とによって３つの紫外線照射室１０が形成され、各紫外線照射室１０の内部には２本の紫外線ランプ１２が配設されている。また、異なる段に位置する各垂直透明板８は、互いに同一の垂直面上に配置されている。
【００２０】
紫外線照射室１０を除く光酸化反応室６内は、粒径３mmの粒状担体に担持された酸化チタンからなる光触媒１３が充填された光触媒充填室１４となっている。粒状の光触媒１３は、その充填部が充填室１４の４０容量％を占め、下方から吹き上げてくる空気流によって流動化される。従って、底部仕切板５ａだけでなく、傾斜透明板８も流動床として機能する。
最上段の中間空気溜り７の上方には、所定の間隔を介して、１０メッシュの金網からなる第二仕切板１５ａ，１５ｂが装置本体１に固定されており、第二仕切板１５間の空間内は粒径３mmの粒状の活性炭１６が充填された活性炭充填層１７となっている。また、充填層１７の装置本体１側壁には、汚染物質の吸着能が低下した活性炭１６を取り出す活性炭取出口１８が設けられている。第二上部仕切板１５ｂの上方には、上方に向かって縮径する上部空気溜り１９が形成され、その上方中央に空気溜り１９に連通する空気排出口２０が形成されている。
【００２１】
次に、実施例に示す空気浄化装置の作用を説明する。
まず、送風機を回転駆動すると、汚染物質を含む空気が空気浄化装置本体１底部の流入口４から流入し、装置内部をほぼ一定の流速で上昇するように形成された下部空気溜り３で汚染空気は整流される。空気溜り３を通過した汚染空気は、第一仕切板５ａの網目から最下段の光触媒充填室１４に流入する。
充填室１４には光触媒１３が密に堆積しており、空気中の汚染物質が光触媒１３と接触することにより吸着される。また、粒状の光触媒１３は、下方から吹き上げられる空気によって上向きに舞い上がり、透明板８，９の水平方向間隔が上方に向かって広がっている充填室１４の上部でバラバラに拡散される。光触媒１３の流動化は、その自重と送風機による空気の上昇流によりバランスする。
【００２２】
一方、紫外線照射室１０は光透過性の透明板８，９及び反射板１１で３方向から囲繞されており、その内部に配設された紫外線ランプ１２から紫外線が光触媒充填室１４に照射される。そのため、光触媒１３粒子に吸着された汚染物質は、紫外線と光触媒の強力な酸化作用により分解される。例えば、臭気物質のアンモニアは水と窒素ガスに分解され、ホルムアルデヒドは水と炭酸ガスに分解されて無臭物質に変化する。
１段目の光触媒充填室１４で分解されなかった汚染物質を含む空気は、その上方の中間空気溜り７で整流され、２段目の光触媒充填室１４において同様に光酸化分解作用を受ける。このようにして、汚染物質は上段の光触媒充填室１４に上昇するに従って次第に分解される。
【００２３】
更に、汚染空気は、最上段の中間空気溜り７を経由して、第二底部仕切板１５ａの網目から活性炭充填層１７に流入し、分解されなかった汚染物質が粒状の活性炭１６にほぼ完全に吸着される。
以上のようにして浄化された空気は、上部空気溜り１９を経由して、装置本体１頂部の空気排出口２０から大気中へ放出される。
【００２４】
【発明の効果】
本発明によれば、前述した通り、光触媒の飛散状態と循環状態が良好であり、しかも光触媒に紫外線が充分に照射されるので、光触媒に吸着された汚染物質が効率よく分解される。また、本発明によれば、光酸化反応室において汚染物質のショートパスが回避され、汚染物質が未処理のまま浄化装置の系外に放出されることが防止される。
【図面の簡単な説明】
【図１】本発明の光分解による汚染空気の浄化装置の断面図である。
【符号の説明】
１・・・空気浄化装置本体、４・・・空気流入口、５ａ，５ｂ・・・第一仕切板、６・・・光酸化反応室、８・・・垂直透明板、９・・・傾斜透明板、１０・・・紫外線照射室、１２・・・紫外線ランプ、１３・・・光触媒、１５ａ，１５ｂ・・・第二仕切板、１６・・・活性炭、１７・・・活性炭充填層、２０・・・空気排出口。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air purification apparatus and method for photolyzing pollutants contained in air. More specifically, the present invention relates to a polluted air purification apparatus and method for oxidizing and decomposing pollutants such as ammonia, amines, mercaptans, and organic chlorine compounds contained in air by the action of a photocatalyst and ultraviolet irradiation.
[0002]
[Prior art]
Odorous components such as ammonia, amines, mercaptans, etc. generated from garbage disposal plants and industrial waste disposal plants have been a problem of pollution for many years, leaving discomfort to the residents around the treatment plants. In addition, organic chlorine compounds such as trichlorethylene and tetrachlorethylene have been used in large quantities in dry cleaning factories, metal degreasing processes, substrate cleaning processes, etc., but some of them penetrated underground and further mixed into groundwater. It is reported that there are health concerns. As a method for removing volatile organic chlorine compounds contained in groundwater, the present applicant has proposed a method in which an organic chlorine compound is vaporized by an appropriate means and then decomposed (Japanese Patent Application No. 2001-238785). ).
As a general method for removing organochlorine compounds contained in the air, for example, a method of adsorbing to an adsorbent such as activated carbon, a method of decomposing by contacting with a catalyst under heating, a method by plasma discharge, etc. are known. . However, the adsorption method requires post-treatment of the adsorbent, the catalytic cracking method requires considerable energy to heat the catalyst, and the plasma discharge method requires a large amount of power. It was.
[0003]
In recent years, a photodegradation technique for oxidatively decomposing an organic substance by combining a photocatalyst and ultraviolet irradiation has been developed, and many proposals have been made using this for a method for removing an organic chlorine compound. A few examples are as follows.
For example, a method has been proposed in which a photocatalyst film is fixed to a tube wall or the like that is a contact surface with exhaust gas, and the organic catalyst is decomposed by irradiating the photocatalyst film with ultraviolet rays. However, this method has a problem that the surface area of the photocatalyst film is small and the decomposition efficiency is not good. In order to increase the contact area with the exhaust gas, it is conceivable that the photocatalyst has a honeycomb structure, but in that case, it is difficult to irradiate ultraviolet rays to the back of the photocatalyst film, and the improvement of the decomposition efficiency can also be expected. It is not considered.
[0004]
In addition, the photocatalyst powder is blown into the exhaust gas to adsorb the organochlorine compound, and the photocatalyst is irradiated with ultraviolet rays by an ultraviolet lamp installed in a space partitioned by a bag filter in the dust collecting part to decompose the organochlorine compound. A method has been proposed (Japanese Patent Laid-Open No. 10-32853). However, in this method, since it is necessary to install an ultraviolet lamp (ultraviolet irradiation source) inside the photodecomposition apparatus, the irradiation intensity of the ultraviolet rays decreases due to contamination of the irradiation source, and degradation efficiency is unavoidable. There is a problem.
Furthermore, a method has been proposed in which a granular photocatalyst carrier is used to decompose an organochlorine compound while flowing the photocatalyst carrier by blowing air to be treated and stirring by feeding water to be treated (Japanese Patent Laid-Open No. 2001-79351). JP, 2001-191067, A). However, in this method, the fluidity of the photocatalyst carrier is not so good, so a very small amount of the organic chlorine compound in the thin film concentration is not adsorbed on the photocatalyst carrier, and is released from the reactor system in a short pass without being treated. There is a possibility that.
[0005]
[Problems to be solved by the invention]
As described above, in the method for decomposing and removing organic substances by the combination of photocatalyst and ultraviolet irradiation, the irradiation intensity from the ultraviolet irradiation source gradually decreases to deteriorate the decomposition efficiency of pollutants, and the contamination of extremely low concentration is also reduced. In the case of decomposing and removing the substance (organochlorine compound), there is a problem that the contaminant is not sufficiently adsorbed by the photocatalyst.
Accordingly, an object of the present invention is to eliminate the above-mentioned problems of the prior art, and it is possible to sufficiently irradiate the photocatalyst with ultraviolet rays from an ultraviolet irradiation source, and the concentration of pollutants in the air is several hundred ppb. Even at extremely low concentrations, it is possible to prevent pollutants from being discharged outside the system without being treated, and to purify polluted air by photolysis with excellent pollutant decomposition efficiency. It is to provide an apparatus and a method thereof.
[0006]
[Means for Solving the Problems]
The inventors of the present invention have made extensive studies in order to solve the above-described problems of the prior art. In an air purification apparatus in which a plurality of photo-oxidation reaction chambers and activated carbon packed layers are formed, a light transmissive vertical By forming a triangular ultraviolet irradiation chamber composed of a transparent plate and an inclined transparent plate in each photooxidation reaction chamber, the photocatalyst filled in the photooxidation reaction chamber is maintained in a good circulation state, and this flow state As a result of sufficiently irradiating the photocatalyst with ultraviolet rays, it was found that the pollutants were efficiently decomposed, and the present invention was made.
[0007]
That is, the polluted air purification apparatus by photolysis of the present invention is provided with an air inlet and an air outlet respectively below and above the apparatus main body, and a plurality of photooxidation reaction chambers are formed at the lower part inside the apparatus main body. In the purification apparatus for polluted air by photolysis, an activated carbon packed layer is formed on the top, and each upper and bottom of each photooxidation reaction chamber and the activated carbon packed layer are partitioned by a partition plate having a large number of ventilation holes. Inside the photo-oxidation reaction chamber, an ultraviolet irradiation chamber having a substantially triangular cross-sectional shape composed of a light-transmitting vertical transparent plate, an inclined transparent plate, and a partition plate at the bottom of the photo-oxidation reaction chamber is formed. At the same time, an ultraviolet irradiation source is disposed inside the ultraviolet irradiation chamber, the photooxidation reaction chamber excluding the ultraviolet irradiation chamber is partially filled with a granular photocatalyst, and the activated carbon packed bed has a granular shape. Filled with activated carbon It is characterized in.
[0008]
Further, in the method for purifying polluted air by photolysis according to the present invention, air containing pollutants is introduced into the lowermost photooxidation reaction chamber through a partition plate at the bottom of the apparatus main body having a large number of ventilation holes, and a plurality of stages are provided. While the oxidative decomposition of the pollutant is caused by the action of the photocatalyst and ultraviolet irradiation in the photooxidation reaction chamber, the activated carbon packed bed is filled with undegraded pollutants contained in the air that has passed through the uppermost photooxidation reaction chamber. after adsorption on activated carbon, in the above method for purifying polluted air by photolysis to release the purified air from the apparatus body, in the interior of the photooxidation chamber, a light-permeable vertical transparent plate and inclined transparent plate A granular photocatalyst in which an ultraviolet irradiation chamber having a substantially vertical cross-sectional shape composed of a partition plate at the bottom of the photooxidation reaction chamber is formed and partially filled in the space of the photooxidation reaction chamber excluding the ultraviolet irradiation chamber Air flow rising from below Ri while fluidizing, contaminants from placed ultraviolet radiation source ultraviolet irradiation chamber is irradiated with ultraviolet light catalyst adsorbed, characterized by oxidative decomposition of pollutants in the air.
[0009]
[Action]
As described above, the device for purifying contaminated air by photolysis of the present invention comprises a plurality of photooxidation reaction chambers and activated carbon packed layers each partitioned by a partition plate having a large number of ventilation holes, and is a light-transmitting vertical transparent plate Are formed in each photooxidation reaction chamber.
The method for purifying polluted air according to the present invention comprises a method of adsorbing undegraded pollutants to activated carbon while oxidizing and decomposing pollutants by the action of a photocatalyst and ultraviolet irradiation in a plurality of photooxidation reaction chambers. The photocatalyst fluidized by the air flow is irradiated with ultraviolet rays from the ultraviolet irradiation chamber.
[0010]
Therefore, the pollutant is first surely adsorbed on the granular photocatalyst at the bottom deposition portion of the photooxidation reaction chamber. Moreover, the photocatalyst is blown up and diffused upward by the air flow rising along the vertical transparent plate and the inclined transparent plate, and the scattered photocatalyst portion is efficiently irradiated with ultraviolet rays, so that the pollutant adsorbed on the photocatalyst is absorbed. Can be efficiently oxidized and decomposed. Furthermore, since the fluidized bed is composed of the bottom partition plate and the inclined transparent plate so that the photocatalyst falls along the inclined transparent plate and deposits on the bottom partition plate, the photocatalyst is good in the photooxidation reaction chamber. Circulation is maintained.
Further, in the polluted air purifying apparatus and method of the present invention, a plurality of photooxidation reaction chambers having the above-described structure and an activated carbon packed bed are disposed above them. Therefore, a short path of pollutants is avoided in the photooxidation reaction chamber, and the undecomposed pollutants contained in the air passing through the uppermost photooxidation reaction chamber are adsorbed by the granular activated carbon packed in the activated carbon packed bed. Therefore, it is possible to prevent the pollutant from being released out of the purification apparatus without being treated.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail.
The pollutant to be treated according to the present invention is not particularly limited as long as it is a volatile substance that is harmful to health or emits a bad odor even at a very low concentration. For example, organic substances such as trichloroethylene, tetrachloroethylene, and trichloroethane can be used. In addition to chlorine-based solvents, amines such as ammonia and trimethylamine, mercaptans such as hydrogen sulfide and methyl sulfide, and odorous substances such as formaldehyde can be used.
As described above, the apparatus and method for purifying contaminated air by photolysis according to the present invention has a plurality of photooxidation reaction chambers formed in the lower part of the apparatus body, and an activated carbon packed bed formed in the upper part. Each photo-oxidation reaction chamber and activated carbon packed bed has a bottom portion and an upper portion having a large number of ventilation holes so that air containing contaminants introduced from the lower part of the apparatus main body can be vented and purified air is discharged from the upper part of the apparatus main body. It is partitioned by a partition plate. As the partition plate, a metal mesh or a punching metal in which pores such as a circle, an ellipse, a square, and a star are formed is preferably used. The size of the mesh or pores may be such that the granular photocatalyst or activated carbon does not fall out of the partition plate.
[0012]
The photo-oxidation reaction chamber takes into account the concentration of pollutants contained in the air, the volume of air per unit time, the amount of photocatalyst, the decomposition efficiency of pollutants, etc. Can be increased.
In each photo-oxidation reaction chamber, an ultraviolet irradiation chamber composed of a light-transmitting vertical transparent plate and an inclined transparent plate is formed together with the bottom partition plate. The partition plate portion that forms the ultraviolet irradiation chamber is a plate-like member that closes the mesh or pores or does not previously have pores so that the fine photocatalyst generated during operation does not enter the ultraviolet irradiation chamber. It is preferable. Further, the ultraviolet irradiation chamber may be further formed by combining the side wall of the apparatus main body of the photooxidation reaction chamber and the inclined transparent plate. Thus, a plurality of ultraviolet irradiation chambers are usually formed in one photooxidation reaction chamber, and one or a plurality of ultraviolet irradiation sources are arranged inside each ultraviolet irradiation chamber.
[0013]
It is preferable that the ultraviolet irradiation chamber has a substantially triangular cross-sectional shape, and the inclined angle of the inclined transparent plate inclined toward the ultraviolet irradiation chamber with respect to the bottom partition plate is in the range of 50 to 70 °.
The inclination angle is more preferably in the range of 55 to 65 °, and particularly preferably in the range of 57 to 63 °. When the inclination angle is less than 50 °, the total opening area of the partition plate through which air flows from below is small, and the fluidity of the photocatalyst decreases. On the other hand, when the angle is larger than 70 °, the inflowing air is not diffused so much in the upper part of the photooxidation reaction chamber, and the oxidative decomposition efficiency of pollutants due to the fluidization of the photocatalyst decreases. In addition, the space of the ultraviolet irradiation chamber is small, and the maintenance and inspection work of the ultraviolet irradiation source disposed inside the chamber becomes difficult.
[0014]
A vertical transparent plate and an inclined transparent plate are disposed between the bottom partition plate and the upper partition plate, and no gap is provided between the upper end portion of the ultraviolet irradiation chamber where both transparent plates abut and the upper partition plate. preferable. Thereby, since the photocatalyst filled in one space of the photo-oxidation reaction chamber does not move to the other space, the contaminant can be stably oxidatively decomposed for a long period of time.
The vertical transparent plate and the inclined transparent plate are made of a material excellent in light transmittance, that is, ultraviolet light transmittance, such as glass or polymethyl methacrylate. As the ultraviolet irradiation source, an ultraviolet lamp that irradiates ultraviolet rays having a wavelength of 390 nm or less is usually used. In addition, a reflective thin film is deposited or a reflecting plate is stretched on the surface of the inner wall of the apparatus main body constituting the photooxidation reaction chamber, particularly the ultraviolet irradiation chamber, and further on the surface of the bottom partition plate. Hereinafter, it can also be represented by a reflector. In that case, it is preferable that the ultraviolet rays irradiated from the ultraviolet irradiation source are irregularly reflected by, for example, a roughened reflector or the like, and the photooxidative decomposition action is further enhanced.
[0015]
The inside of the photooxidation reaction chamber excluding the ultraviolet irradiation chamber is partially filled with a particulate photocatalyst. Examples of the photocatalyst include titanium oxide, zinc oxide, and tungsten oxide. These photocatalysts are carried on the surface and inside of a granular porous carrier such as zeolite, silica gel, alumina, and porous glass. The particle size of the photocatalyst carrier is in the range of 1.5 to 10 mm, and preferably in the range of 2 to 4 mm. Moreover, it is preferable that the apparent filling rate of the photocatalyst with respect to the photo-oxidation reaction chamber except an ultraviolet irradiation chamber exists in the range of 20-70 volume%.
When the particle size of the photocatalyst is less than 1.5 mm, it is necessary to make the meshes or pores of the bottom and the upper partition plate smaller than the particle size of the photocatalyst support, and the opening area per unit area of the partition plate is small. The resistance of the partition plate with respect to the air supplied from below by the blower increases. On the other hand, when the particle size is larger than 10 mm, the fluidity of the photocatalyst decreases. When the filling rate is less than 20% by volume, the oxidative decomposition efficiency of the pollutant per unit volume of the photooxidation reaction chamber excluding the ultraviolet irradiation chamber cannot be ensured sufficiently. On the other hand, when the filling rate is larger than 70% by volume, the fluidity of the photocatalyst is lowered and the photocatalyst is not sufficiently circulated in the photooxidation reaction chamber.
[0016]
The activated carbon packed bed is filled with granular activated carbon formed by activating carbonaceous material. The activated carbon packed bed can be divided into a plurality of layers as appropriate. Moreover, it is not always necessary to fill the entire inside of the packed bed with activated carbon.
The activated carbon packed bed is preferably filled with activated carbon for basic gas, neutral gas, and acidic gas alone or in combination depending on the nature of the pollutant contained in the contaminated air. For example, when the pollutant to be treated is an organic chlorine compound, when the air passes through the photocatalyst, it is decomposed into HCl, CO ₂ and H ₂ O, and the treated air tends to contain an acidic gas. In that case, it is preferable to fill the granular activated carbon modified to be basic for acid gas adsorption.
The particle size of the activated carbon is in the range of 2-6 mm. When the particle size of the activated carbon is less than 2 mm, the resistance of air passing through the activated carbon packed bed is increased. On the other hand, if the particle size is larger than 6 mm, the surface area of the activated carbon per unit volume becomes small, and the adsorption efficiency of the pollutant decreases, which is not preferable.
[0017]
Furthermore, it is preferable to form an air reservoir below the lowermost photooxidation reaction chamber so that the flow rate of air flowing into the photooxidation reaction chamber filled with the photocatalyst is made uniform. Similarly, between the upper partition plate of the photooxidation reaction chamber located below and the bottom partition plate of the photooxidation reaction chamber located above, and the upper partition plate of the uppermost photooxidation reaction chamber and the activated carbon packed bed It is preferable to form an air reservoir between each of the bottom partition plates.
If at least one of these air pockets is formed, uneven adsorption of contaminants on the photocatalyst and / or activated carbon is reduced. For example, when an air pool is formed between the partition plates of different photo-oxidation reaction chambers, the photocatalyst flows and circulates almost uniformly, and the oxidative decomposition efficiency of pollutants is improved.
[0018]
【Example】
Hereinafter, the present invention will be described more specifically with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an air purification device main body formed from a tower having a substantially square shape. Four legs 2 are attached to the bottom of the device main body 1 to support it. In addition, a lower air reservoir 3 that expands upward is formed in the lower part of the apparatus body 1, an air inlet 4 that communicates with the lower air reservoir 3 is formed in the lower center, and a blower (not shown) is located behind the air inlet 4. ) Is arranged.
The apparatus main body 1 is partitioned by a first bottom partition plate 5a made of a 10-mesh wire mesh and a first upper partition plate 5b made of the same wire mesh as the partition plate 5a with a predetermined interval therebetween. The photo-oxidation reaction chamber 6 and the intermediate air reservoir 7 thereabove are formed in a plurality of stages. FIG. 1 shows an example in which the photooxidation reaction chamber 6 and the intermediate air reservoir 7 are formed in two stages.
[0019]
Between the first partition plates 5a and 5b of the photooxidation reaction chamber 6, a plurality of vertical transparent plates 8 and inclined transparent plates 9 made of light-transmitting glass are arranged, and the transparent plates 8 and 9 and the bottom partition plate 5a. The space partitioned by is an ultraviolet irradiation chamber 10. The partition plate 5a constituting the ultraviolet irradiation chamber 10 is closed with a reflecting plate 11. The upper ends of the transparent plates 8 and 9 are in contact with each other at an inclination angle of 30 ° (thus, the inclination angle of the inclined transparent plate 9 with respect to the bottom partition plate 5a is 60 °). An ultraviolet lamp 12 that irradiates near ultraviolet rays is disposed inside the ultraviolet irradiation chamber 10.
In FIG. 1, three ultraviolet irradiation chambers 10 are formed by three inclined transparent plates 9, a reflection plate 11, two vertical transparent plates 8, and a reflection plate on the inner wall surface of the apparatus body 1. Two ultraviolet lamps 12 are disposed inside. In addition, the vertical transparent plates 8 located on different stages are arranged on the same vertical plane.
[0020]
The photo-oxidation reaction chamber 6 excluding the ultraviolet irradiation chamber 10 is a photocatalyst filling chamber 14 filled with a photocatalyst 13 made of titanium oxide supported on a granular carrier having a particle diameter of 3 mm. The granular photocatalyst 13 occupies 40% by volume of the filling chamber 14 and is fluidized by the air flow blown from below. Therefore, not only the bottom partition plate 5a but also the inclined transparent plate 8 functions as a fluidized bed.
Above the uppermost intermediate air reservoir 7, second partition plates 15 a and 15 b made of a 10-mesh wire mesh are fixed to the apparatus main body 1 through a predetermined interval. The inside is an activated carbon packed layer 17 filled with granular activated carbon 16 having a particle diameter of 3 mm. Further, an activated carbon outlet 18 for taking out the activated carbon 16 having a reduced ability to adsorb contaminants is provided on the side wall of the main body 1 of the packed bed 17. Above the second upper partition plate 15b, an upper air reservoir 19 that is reduced in diameter upward is formed, and an air discharge port 20 that communicates with the air reservoir 19 is formed at the upper center thereof.
[0021]
Next, the operation of the air purification device shown in the embodiment will be described.
First, when the blower is driven to rotate, air containing pollutants flows from the inlet 4 at the bottom of the air purification device main body 1 and contaminated air in the lower air reservoir 3 formed so as to rise inside the device at a substantially constant flow rate. Is rectified. The contaminated air that has passed through the air reservoir 3 flows into the lowermost photocatalyst filling chamber 14 from the mesh of the first partition plate 5a.
The photocatalyst 13 is densely deposited in the filling chamber 14, and contaminants in the air are adsorbed by coming into contact with the photocatalyst 13. Further, the granular photocatalyst 13 rises upward by the air blown from below, and is diffused apart at the upper part of the filling chamber 14 where the horizontal interval between the transparent plates 8 and 9 spreads upward. The fluidization of the photocatalyst 13 is balanced by its own weight and the upward flow of air by the blower.
[0022]
On the other hand, the ultraviolet irradiation chamber 10 is surrounded by light transmissive transparent plates 8 and 9 and a reflecting plate 11 from three directions, and the photocatalyst filling chamber 14 is irradiated with ultraviolet rays from an ultraviolet lamp 12 disposed therein. . Therefore, the contaminant adsorbed on the photocatalyst 13 particles is decomposed by the strong oxidizing action of ultraviolet rays and the photocatalyst. For example, the odorous ammonia is decomposed into water and nitrogen gas, and formaldehyde is decomposed into water and carbon dioxide gas to change to odorless materials.
The air containing the pollutant that has not been decomposed in the first-stage photocatalyst filling chamber 14 is rectified in the intermediate air reservoir 7 thereabove and is similarly subjected to the photooxidative decomposition action in the second-stage photocatalyst filling chamber 14. In this way, the contaminants are gradually decomposed as they rise into the upper photocatalyst filling chamber 14.
[0023]
Furthermore, the contaminated air flows into the activated carbon packed bed 17 from the mesh of the second bottom partition plate 15 a via the uppermost intermediate air reservoir 7, and the undecomposed contaminants almost completely enter the granular activated carbon 16. Adsorbed.
The air purified as described above is discharged into the atmosphere from the air outlet 20 at the top of the apparatus main body 1 via the upper air reservoir 19.
[0024]
【The invention's effect】
According to the present invention, as described above, the scattered state and the circulating state of the photocatalyst are good, and the photocatalyst is sufficiently irradiated with ultraviolet rays, so that the contaminant adsorbed on the photocatalyst is efficiently decomposed. In addition, according to the present invention, a short path of contaminants is avoided in the photooxidation reaction chamber, and the contaminants are prevented from being discharged out of the purification apparatus without being treated.
[Brief description of the drawings]
FIG. 1 is a sectional view of an apparatus for purifying contaminated air by photolysis according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Air purification apparatus main body, 4 ... Air inflow port, 5a, 5b ... 1st partition plate, 6 ... Photo-oxidation reaction chamber, 8 ... Vertical transparent plate, 9 ... Inclination Transparent plate, 10 ... UV irradiation chamber, 12 ... UV lamp, 13 ... Photocatalyst, 15a, 15b ... Second partition plate, 16 ... Activated carbon, 17 ... Activated carbon packed bed, 20 ... Air outlet.

Claims

An air inlet and an air outlet are provided below and above the main body of the apparatus, a multi-stage photo-oxidation reaction chamber is formed in the lower part of the main body of the apparatus, and an activated carbon packed bed is formed on the upper part of each chamber. In each of the photo-oxidation reaction chambers, a light-transmitting vertical transparent material is provided in the purification device for contaminated air by photolysis in which the upper and bottom portions of the chamber and the activated carbon packed bed are partitioned by a partition plate having a number of ventilation holes. An ultraviolet irradiation source is disposed inside the ultraviolet irradiation chamber, while the vertical cross-sectional shape composed of the plate, the inclined transparent plate, and the partition plate at the bottom of the photooxidation reaction chamber forms a substantially triangular ultraviolet irradiation chamber. In addition, the photooxidation reaction chamber except for the ultraviolet irradiation chamber is partially filled with granular photocatalyst, and the activated carbon packed bed is filled with granular activated carbon. Air purification equipment

2. The polluted air purifier according to claim 1, wherein the inclined transparent plate inclined toward the ultraviolet irradiation chamber side with respect to the bottom partition plate of the photo-oxidation reaction chamber is in the range of 50 to 70 degrees.

The polluted air purifier according to claim 1, wherein the ultraviolet irradiation chamber is further formed of an inclined transparent plate, an inner wall of the device main body, and a partition plate.

The apparatus for purifying contaminated air according to claim 3, wherein the surface of the inner wall of the apparatus main body is configured as a reflecting surface.

Air containing pollutants is introduced into the lowermost photooxidation reaction chamber through a partition plate at the bottom of the main body of the apparatus having a large number of ventilation holes, and pollutants are generated by the action of the photocatalyst and ultraviolet irradiation in the multiple photooxidation reaction chambers. Oxidative decomposition, and adsorbing undecomposed pollutants contained in the air that has passed through the uppermost photo-oxidation reaction chamber to the granular activated carbon packed in the activated carbon packed bed, and then purifying the air from the device body. In the method for purifying polluted air by photodecomposition to be released, each photooxidation reaction chamber has a longitudinal cross section formed by a light transmissive vertical transparent plate, an inclined transparent plate, and a partition plate at the bottom of the photooxidation reaction chamber. An ultraviolet irradiation chamber having a substantially triangular shape is formed, and ultraviolet irradiation is performed while the granular photocatalyst partially filled in the space of the photooxidation reaction chamber excluding the ultraviolet irradiation chamber is fluidized by an air flow rising from below. Purple placed in the room And contaminants from the line radiation source and irradiated with ultraviolet rays photocatalyst adsorbed, method for purifying polluted air by photolysis characterized by oxidative decomposition of pollutants in the air.