JP3651780B2 - Ozone generator - Google Patents

Description

ここで、kはボルツマン定数［1.38×10^-16erg/K］、Tはガス温度［K］、mは気体分子1個の質量[g]を表わす。
【００５９】
オゾンの質量は、１mol当たり48 [g]なので、１分子当たりの質量m_O3は
【数２】

例えば、ガス温度T=300[K]では、オゾン分子の速度は
【数３】

引き続き、図６に示すような単位体積の空間を考えて、壁面との衝突を考える。
【００６０】
壁面1cm²当たりの分子の衝突頻度f_wall［cm^-2s^-1］は、他のガス分子との衝突を無視すると
【数４】

となる。
【００６１】
係数1 / 4の理由は、分子のうち壁面の方にむかうものと反対方向に向かうものがあるのでn / 2となり、壁面に垂直方向成分の平均が 1/2となるためである。
【００６２】
例えば、大気圧においてオゾン濃度が15%では、オゾンの数密度n_O3は
【数５】

なので、衝突頻度f_O3-wallは
【数６】

壁面に衝突するオゾン分子のうち、z_wallの確率で分解が生じるものとする。
【００６３】
分解しないオゾンは、壁面で跳ね返されることになる。この反射率Rは、以下のような式で定義される。
【００６４】
【数７】

単位体積当たりのオゾン数密度[03]が壁面で分解するレートは、毎秒当たり
【数８】

で表わされる。
【００６５】
h_chが0.06 [cm] (=0.6mm)で、z_wallが1.0×10^-6という大変小さな値でも、オゾン数密度の減少レートは、毎秒当たり
【数９】

である。
【００６６】
オゾン生成量は、酸素分子の電子衝突による解離効率は、オゾン発生装置内部の典型的な電界強度100〜200[Td]において
【数１０】

である。
【００６７】
解離した酸素原子は、100％がオゾンになるとすると、酸素分子１つからオゾンが2つ発生する。
【００６８】
電子へのエネルギー分岐be=0.38とし、電力を6.6[W/cm³]とすると
【数１１】

従って、上記(１５)式と(１７)式とを比較すると、壁面での分解は発生の20％に及ぶことがわかる。
【００６９】
以上により、誘電体層４の表面材料を変えることで、誘電体層４におけるオゾン分子衝突面である壁面との衝突によるオゾンの分解確率z_wallは変化することになる。
【００７０】
本実施の形態では、従来知られていなかったこのような反応についてさまざまな物質を試した結果、超高濃度オゾン発生に適した誘電体層４の材料を、オゾン発生装置を構成するオゾン発生電極プレートに適用するものである。
【００７１】
ところで、誘電体層４は、一般に、ガラスからなる基板１と密着接合している必要がある。
【００７２】
なぜなら、基板１と密着接合していないと、誘電体層４と基板１との間に空隙が存在することになるため、電極２，３の間にこの空隙を介して絶縁破壊を生じ、オゾンを発生できなくなる。
【００７３】
これらを密着接合するためには、誘電体層４の線膨張係数は、ガラスからなる基板１の線膨張係数とほぼ合致している必要がある。
【００７４】
基板１は、工業的にはソーダガラスが、物量、コスト面でもっとも入手し易い。ソーダガラスは、線膨張係数が７０〜１００×１０^-7で、ガラスの中では大きな値を示している。そのため、通常、誘電体層４として、酸化鉛を４０ｗｔ％（重量パーセント）以上含むいわゆる鉛ガラスが用いられている。
【００７５】
この鉛ガラスを誘電体層４として、オゾン原料ガス１０を、９９．９％以上酸素を含む純酸素ガスとして、本実施の形態の沿面放電方式のオゾン発生装置に導入する。
【００７６】
そして、このような状態（基板１をソーダガラスとし、誘電体層４を鉛ガラスとした状態）下で、電極２，３に交流電源９から高い交流電圧を印加して、誘電体層４表面に沿面放電１１を発生させ、この沿面放電１１によってオゾン原料ガス１０からオゾン１２を生成する。
【００７７】
図７は、誘電体層４として、ビスマスガラス、酸化鉛を用いた場合のオゾン発生特性を示す特性図であり、この図中の酸化鉛がいわゆる鉛ガラスである。
【００７８】
図７において、横軸はオゾン濃度、すなわち標準状態（摂氏０度、１気圧）における単位立法メ−トル体積当たりのオゾングラム数を表わし、縦軸はオゾン収率、すなわち単位電力量であるキロワット時当たり発生できるオゾン量であるグラム数を表わす。
【００７９】
オゾン濃度は最大１０ｇ／Ｎｍ³以下であり、オゾン収率は最大１０ｇ／ｋＷｈ以下である。これは、従来から産業用に用いられてきた体積放電方式のオゾン発生装置で生成される最大オゾン濃度２００ｇ／Ｎｍ³、最大オゾン収率１４０ｇ／ｋＷｈと比較して、非常に小さく実用的ではない。
【００８０】
そこで、誘電体層４の材料として、酸化鉛含有量を４０ｗｔ％以下に抑制し、かつ基板１の材料であるソーダガラスと合致する線膨張係数を有する、いわゆるビスマスガラスを用いると、極めて高いオゾン発生特性を得ることができる。
【００８１】
図７に示すように、誘電体層４としてビスマスガラスを用いた場合の方が、酸化鉛を用いた場合に比べて、オゾン濃度、オゾン収率ともに、極めて高い値を得ることができ、有利である。
【００８２】
この理由は、上記（５）式、（６）式に示したような反応が、ビスマスガラス表面では生じないためである。
【００８３】
このビスマスガラスの組成としては、酸化鉛含有量を０〜４０重量パーセント（ｗｔ％）に抑え、残りの物質として、酸化ビスマスを１０〜９０重量パーセント（ｗｔ％）、酸化亜鉛を１０〜９０重量パーセント（ｗｔ％）含有することにより、基板１であるソーダガラスとほぼ合致する線膨張係数を得ることができる。
【００８４】
特に、酸化亜鉛を３０〜４０重量パーセント（ｗｔ％）、酸化ビスマスを２０〜３０重量パーセント（ｗｔ％）、酸化ホウ素を１５〜２５重量パーセント（ｗｔ％）、酸化珪素を０〜１０重量パーセント（ｗｔ％）含有する組成とすることにより、基板１であるソーダガラスとの線膨張係数は完全に合致する。
【００８５】
その結果、誘電体層４は基板１と密着接合して、電極２，３の間に空隙を生じず、高い絶縁性を得ることができ、安定した高濃度オゾンを生成させることができる。
【００８６】
一方、電力密度が高くなって、同じ電力でより高いオゾン収率を確保できるため、交流電圧印加用の電源８を小形化して、装置全体をコンパクトにすることができる。
【００８７】
また、高濃度オゾンを生成するのに、オゾン原料ガス１０へ添加ガスを添加する必要がなくなるため、添加ガス添加用の装置（窒素ボンベ３６から、減圧弁３７、および窒素流量計３８）が不要となり、装置全体を簡素化して、安価でかつ信頼性の高い装置を得ることができる。
【００８８】
さらに、オゾン応用分野の一つとして半導体プロセスがあり、オゾンアッシングや酸化膜堆積等の化学反応プロセスで窒素ガス混入を嫌う場合があるが、本オゾン発生装置では窒素ガスを添加ガスとして混入しないでもよいため、上記用途に最適に用いることができる。
【００８９】
また、交流電圧印加用の電源８からの印加電圧の大きさを低くできるため、配線７の取出部分等における異常放電の恐れがなくなり、結果として信頼性を高めることができる。
【００９０】
さらに、基板１と誘電体層４の線膨脹係数をほぼ同じにできるため、基板１と冷却板６とを密着させて冷却効率を高めることができる。
【００９１】
上述したように、本実施の形態の沿面放電方式のオゾン発生装置では、基板１の上に設けられた対をなす電極２，３を被覆する誘電体層４の材料として、酸化ビスマスを１０〜９０重量パーセント（ｗｔ％）、酸化亜鉛を１０〜９０重量パーセント（ｗｔ％）含有し、かつ酸化鉛含有量が０〜４０重量パーセント（ｗｔ％）の組成を有するものを用いるようにしているので、誘電体層４表面でのオゾン分解反応を抑制して、極めて安定した高濃度オゾンを生成させることが可能となる。
【００９２】
また、誘電体層４として、化学的に安定な少なくとも酸化珪素、酸化亜鉛を用いるようにしているので、上記効果をより一層効果的に顕著に奏することが可能となる。
【００９３】
これらの特性は、オゾンの表面における分解確率z_wallが材料によって異なるために生ずることを、我々は初めて見出した。
【００９４】
図８は、酸化亜鉛、ビスマスガラスの特性に対するオゾン分解確率z_wallの値を換算して示す特性図である。
【００９５】
図８において、縦軸はオゾン濃度Ｃであり、横軸は特性エネルギーＷ／Ｑである。
【００９６】
酸化亜鉛に対して15×10^-7、ビスマスに対して30×10^-7である。これらの値であれば、オゾン発生装置として十分な特性である。
【００９７】
図９は、横軸にオゾン分解確率z_wall 、縦軸に飽和オゾン濃度Csをとって示した特性図である。
【００９８】
図９に示すように、誘電体層４としては、誘電体層４におけるオゾン分子の衝突面の材料が、誘電体層４とオゾン分子との衝突によるオゾンの分解確率z_wallが7×10^-6以下となるようにすることによって、高いオゾン発生特性を得ることが可能となる。
【００９９】
すなわち、この場合、図９に示すように、オゾンの分解確率z_wallが7×10^-6以下となるようにすることで、取りあえず所期の目的を達成する、すなわち従来よりも安定した高濃度オゾンを生成することが可能であるが、例えばビスマスガラスを用いた場合には、図９に示すように、飽和オゾン濃度Ｃｓとして少なくとも２５０ｇ／Ｎｍ^-3以上を確保できればよいが、図８に示すように、オゾン濃度Ｃｓとして３００ｇ／Ｎｍ^-3以上を確保する方が、より安定した高濃度オゾンを生成させることが可能であることを考慮すると、オゾンの分解確率z_wallが7×10^-6 からより小さい値とすることがより好ましい。
【０１００】
さらに、電力密度が高くなって、同じ電力でより高いオゾン収率を確保できるため、交流電圧印加用の電源８を小形化して、装置全体をコンパクトにすることが可能となる。
【０１０１】
さらにまた、高濃度オゾンを生成するのに、オゾン原料ガス１０へ添加ガスを添加する必要がなくなるため、従来では必須であった添加ガス添加用の装置が不要となり、装置全体を簡素化して、安価でかつ信頼性の高い装置を得ることが可能となる。
【０１０２】
一方、オゾン応用分野の一つとして半導体プロセスがあり、オゾンアッシングや酸化膜堆積等の化学反応プロセスで窒素ガス混入を嫌う場合があるが、本実施の形態のオゾン発生装置では、窒素ガスを添加ガスとして混入しないでもよいため、上記用途に最適に用いることが可能となる。
【０１０３】
また、交流電圧印加用の電源８からの印加電圧の大きさを低くできるため、配線７の取出部分等における異常放電の恐れがなくなり、結果として信頼性を高めることが可能となる。
【０１０４】
さらに、基板１と誘電体層４の線膨脹係数をほぼ同じにできるため、基板１と冷却板６とを密着させて冷却効率を高めることが可能となる。
【０１０５】
（第２の実施の形態）
図１０は、本実施の形態による沿面放電方式のオゾン発生装置におけるオゾン発生電極プレートの構成例を示す概要図であり、図１と同一部分には同一符号を付してその説明を省略し、ここでは異なる部分についてのみ述べる。
【０１０６】
すなわち、本実施の形態のオゾン発生電極プレートは、図１０に示すように、前記誘電体層４の上に、パウダー層１３を設けた構成としている。
【０１０７】
ここで、パウダー層１３は、パウダーの粒径を、１０マイクロメートル（μｍ）以下としている。
【０１０８】
また、パウダー層１３は、パウダーとして、酸化珪素、酸化亜鉛を含むものを用いている。
【０１０９】
以上のように構成した本実施の形態の沿面放電方式のオゾン発生装置においては、誘電体層４の上にパウダー層１３を設け、このパウダー層１３のパウダーの粒径を１０マイクロメートル（μｍ）以下としていることにより、均質なパウダー層１３を得ることができ、誘電体層４は、沿面放電１１に直接曝されないため、鉛ガラスを用いてもオゾン発生特性に影響を与えず、オゾン発生特性はパウダー層１３の組成によって大きな影響を受ける。
【０１１０】
図１１は、酸化珪素、ビスマスガラス、酸化亜鉛、アルミナ、チタニア、酸化鉛をパウダー層１３として用い、オゾン原料ガス１０を９９．９％以上酸素を含ひ純酸素ガスとし、電極２，３に交流電源９から高い交流電圧を印加して、誘電体層４表面に沿面放電１１を生じさせ、この沿面放電１１によってオゾン原料ガス１０からオゾン１２を生成した時のオゾン発生特性を示すグラフである。
【０１１１】
図１１に示すように、酸化珪素、ビスマスガラス、酸化亜鉛をパウダー層１３とすると、オゾン濃度、オゾン収率ともに非常に高い値を示す。
【０１１２】
これに比べて、酸化鉛をパウダー層１３とすると、オゾン濃度はゼロであり、オゾン発生装置としての性能が得られない。
【０１１３】
また、アルミナ、チタニアをパウダー層１３とすると、オゾン濃度２０〜１００ｇ／Ｎｍ³で変動が激しく、安定した動作を得ることができない。
【０１１４】
このことは、オゾンの表面における分解反応が触媒作用と関連することを示唆している。
【０１１５】
チタニアは、それ自体、結晶性が変化し易い特性を有するため、触媒として用いられていることは周知の事実である。
【０１１６】
また、アルミナは、それ自体を触媒として用いる例はないが、プラチナ等をアルミナ表面に担持させると触媒作用があることも周知の事実である。
【０１１７】
なお、ここには示していないが、ジルコニア等についても同様である。
【０１１８】
このように、表面反応を抑制するには、触媒として用いられない物質をパウダー層１３として用いると、高いオゾン発生特性を得ることができる。
【０１１９】
図１２は、オゾン原料ガス１０として、酸素ガス９９％に窒素ガス１％を添加した場合のオゾン発生特性を示す特性図である。他は、前述した条件と同様である。
図１２に示すように、酸化鉛以外の物質では、オゾン発生特性は全て良好である。少量の窒素ガスを含むオゾン原料ガス１０が沿面放電１１に曝されると、放電中の電子ｅと窒素分子Ｎ₂ との衝突によって、窒素原子Ｎが発生する。
【０１２０】
ｅ＋Ｎ₂ → ｅ＋Ｎ＋Ｎ ……（１８）
さらに、
Ｎ＋Ｏ₂ → ＮＯ＋Ｏ ……（１９）
ＮＯ＋Ｏ₃ → ＮＯ₂ ＋Ｏ₂ ……（２０）
ＮＯ₂ ＋Ｏ₃ → ＮＯ₃ ＋Ｏ₂ ……（２１）
ＮＯ₂ ＋ＮＯ₃ → Ｎ₂ Ｏ₅ ……（２２）
によって、窒素酸化物（ＮＯ、ＮＯ₂ 、ＮＯ₃ 、Ｎ₂ Ｏ₅ ）が生成する。
【０１２１】
このような窒素酸化物は、物質への吸着性が強く、パウダー層１３表面に付き易い。
【０１２２】
オゾン分解確率z_wallは、表面の様様な分子結合のうち、オゾン分解に寄与するサイトにオゾンが衝突する確率である。窒素酸化物が、このような分解サイトに付着することで、オゾン分解確率z_wallはより小さくなる。
【０１２３】
その結果、オゾンを分解する反応を起こしたチタニアやアルミナといった触媒作用を起こす表面に窒素酸化物が付き、触媒作用が阻害されて高いオゾン発生特性が得られるようになる。
【０１２４】
チタニアやアルミナは、このように微量の窒素ガスのような添加ガスを必要とするもので、添加ガス量に極めて敏感な特性を示す。
【０１２５】
したがって、安定な動作を示す酸化珪素、酸化亜鉛を、パウダー層１３として用いることにより、良好なオゾン発生特性を得ることができる。
【０１２６】
上述したように、本実施の形態の沿面放電方式のオゾン発生装置では、基板１の上に設けられた対をなす電極２，３を被覆する誘電体層４の上に、粒径が１０マイクロメートル（μｍ）以下のパウダーのパウダー層１３を設けるようにしているので、誘電体層４表面でのオゾン分解反応を抑制して、極めて安定した高濃度オゾンを生成させることが可能となる。
【０１２７】
さらに、パウダー層１３のパウダーとして、化学的に安定な酸化珪素、酸化亜鉛を用いるようにしているので、上記効果をより一層効果的に顕著に奏することが可能となる。
【０１２８】
（第３の実施の形態）
図１３は、本実施の形態による沿面放電方式のオゾン発生装置におけるオゾン発生電極プレートの構成例を示す概要図であり、図１と同一部分には同一符号を付してその説明を省略し、ここでは異なる部分についてのみ述べる。
【０１２９】
すなわち、本実施の形態のオゾン発生電極プレートは、図１３に示すように、前記誘電体層４の上に、１マイクロメートル（μｍ）程度の薄膜層１４を設けた構成としている。
【０１３０】
ここで、薄膜層１４は、例えばレジネート法により形成しているものであり、酸化珪素、または酸化亜鉛を含むものを用いている。
【０１３１】
以上のように構成した本実施の形態の沿面放電方式のオゾン発生装置においては、誘電体層４の上にレジネート法により形成された薄膜層１４を設けていることにより、誘電体層４は沿面放電１１に直接曝されないことになる。この影響度は、薄膜層１４の組成による。
【０１３２】
この組成に関しては、前述したパウダー層１３において良好な特性の得られた酸化珪素、酸化亜鉛を、薄膜層１４として用いることにより、良好なオゾン発生特性を得ることが可能である。
さらに、この薄膜層１４は、極めて薄いため、線膨張係数が、基板１、誘電体層４と異なるものであっても剥離せず、安定な特性を得ることができる。
【０１３３】
上述したように、本実施の形態の沿面放電方式のオゾン発生装置では、基板１の上に設けられた対をなす電極２，３を被覆する誘電体層４の上に、レジネート法により形成された薄膜層１４を設けるようにしているので、誘電体層４表面でのオゾン分解反応を抑制して、極めて安定した高濃度オゾンを生成させることが可能となる。
【０１３４】
さらに、薄膜層１４として、化学的に安定な酸化珪素、酸化亜鉛を用いるようにしているので、上記効果をより一層効果的に顕著に奏することが可能となる。
【０１３５】
（その他の実施の形態）
（ａ）前述した第１の実施の形態における誘電体層４の上に、前述した第２の実施の形態のパウダー層１３を設ける構成としてもよい。
【０１３６】
この場合には、第１の実施の形態および第２の実施の形態と同様の作用効果を、同時に得ることが可能となる。
【０１３７】
（ｂ）前述した第１の実施の形態における誘電体層４の上に、前述した第３の実施の形態の薄膜層１４を形成する構成としてもよい。
【０１３８】
この場合には、第１の実施の形態および第３の実施の形態と同様の作用効果を、同時に得ることが可能となる。
【０１３９】
（ｃ）前述した各実施の形態では、沿面放電を用いてオゾンを生成する沿面放電方式のオゾン発生装置に本発明を適用した場合について説明したが、これに限らず、例えば対をなす電極２，３間で無声放電、すなわち体積放電を用いてオゾンを生成する体積放電方式のオゾン発生装置についても、前述の場合と同様に本発明を適用することができるものである。
【０１４０】
図１４は、本実施の形態による体積放電方式のオゾン発生装置の典型例である同軸円筒型オゾナイザの構成例を示す概要図であり、図１と同一要素には同一符号を付している。
【０１４１】
図１４において、ステンレス管４２の内側には、ガラス管４３を挿入している。また、ガラス管４３の内面には金属層４４を設けており、当該金属層４４に高電圧を印加することで、ステンレス管４２とガラス管４３との間の空間に体積放電45が発生する。
【０１４２】
この放電により発生した熱は、冷却水４６によって冷却する。
【０１４３】
原料ガス４７である酸素ガスは、体積放電によってオゾン４８となり、外部に排出するようにしている。
【０１４４】
図１５は、同軸円筒型オゾナイザのオゾン発生特性を示す特性図である。
【０１４５】
図１５において、縦軸はオゾン濃度Ｃ、横軸は特性エネルギーＷ／Ｑである。ガスは、99.9％酸素である。
【０１４６】
この場合にも、壁面のオゾン分解確率z_wallを、1.2×10^-6からより小さい値にすることで、オゾン発生特性の向上を図ることが可能となる。
【０１４７】
特に、7×10-6程度では高い特性が得られず、これ以上の値とすることで、前述したような本発明の内容を適用することができる。
【０１４８】
上述したように、本実施の形態のオゾン発生装置でも、前述した第１乃至第３の実施の形態のオゾン発生装置の場合と、同様の作用効果を得ることが可能となる。
【０１４９】
【発明の効果】
以上説明したように本発明によれば、オゾン原料ガスへの添加ガス成分によって、生成するオゾン濃度が変動しないようにすることが可能なコンパクトでかつ安価でしかも信頼性および安定性の高いオゾン発生装置が提供できる。
【図面の簡単な説明】
【図１】本発明による沿面放電方式のオゾン発生装置の第１の実施の形態を示す概要図。
【図２】同第１の実施の形態のオゾン発生装置におけるオゾン発生電極プレートの構成例を示す概要図。
【図３】同第１の実施の形態のオゾン発生装置の具体的な実装構成例を示す平面図および側断面図。
【図４】同第１の実施の形態のオゾン発生装置の具体的な全体実装構成例を示す概要図。
【図５】同第１の実施の形態のオゾン発生装置における作用効果を説明するための概念図。
【図６】同第１の実施の形態のオゾン発生装置における作用効果を説明するための概念図。
【図７】同第１の実施の形態のオゾン発生装置におけるオゾン発生電極プレートの作用効果を説明するための特性図。
【図８】同第１の実施の形態のオゾン発生装置における作用効果を説明するための特性図。
【図９】同第１の実施の形態のオゾン発生装置における作用効果を説明するための特性図。
【図１０】本発明の第２の実施の形態のオゾン発生装置におけるオゾン発生電極プレートの構成例を示す概要図。
【図１１】同第２の実施の形態のオゾン発生装置におけるオゾン発生電極プレートの作用効果を説明するための特性図。
【図１２】同第２の実施の形態のオゾン発生装置におけるオゾン発生電極プレートの作用効果を説明するための特性図。
【図１３】本発明の第３の実施の形態のオゾン発生装置におけるオゾン発生電極プレートの構成例を示す概要図。
【図１４】本発明による沿面放電方式のオゾン発生装置のその他の実施の形態を示す概要図。
【図１５】同その他の実施の形態のオゾン発生装置における作用効果を説明するための特性図。
【符号の説明】
１…基板
２，３…電極
４…誘電体層
５…冷却水
６…冷却板
７…配線
８…交流電源
９…ガスガイド
１０…オゾン原料ガス（酸素ガス）
１１…沿面放電
１２…オゾン
１３…パウダー層
１４…薄膜層
２１…スペーサ
２２…ケース
２３…電源供給用の端子
３１…オゾン発生装置本体
３３…酸素ボンベ
３４…減圧弁
３５…酸素流量計
３６…窒素ボンベ
３７…減圧弁
３８…窒素流量計
３９…オゾン流量計
４０…減圧弁
４１…オゾン取り出し部
４２…ステンレス管
４３…ガラス管
４４…金属層
４５…体積放電
４６…冷却水
４７…原料ガス
４８…オゾン。[0001]
BACKGROUND OF THE INVENTION
In the present invention, an alternating voltage is applied between a pair of electrodes coated with a dielectric layer to generate a discharge on the surface of the dielectric layer, and ozone is generated from an ozone source gas that fills the space between the pair of electrodes. The present invention relates to an ozone generator, and more particularly to a compact, inexpensive and highly reliable and stable ozone generator in which the concentration of generated ozone is not changed by an additive gas component to ozone raw material gas.
[0002]
[Prior art]
Conventionally, ozone has been widely used for the purpose of sterilizing / deodorizing / decoloring water and sewage, deodorizing / decoloring industrial wastewater treatment, pulp decoloring, and sterilizing medical equipment.
[0003]
As an ozone generator for generating ozone, a device that includes a plurality of electrodes facing each other and generates a silent discharge, that is, a volume discharge between the plurality of electrodes to generate ozone from an ozone source gas is known. .
[0004]
Of these types of ozone generators, those that generate ozone from oxygen gas, which is an ozone raw material gas, can easily generate high-concentration ozone by adding a small amount of nitrogen gas or carbon dioxide gas.
[0005]
In particular, this is remarkable in short gap discharge, and it has been generally performed to add about 2 to 4 percent (%) of nitrogen gas as oxygen source gas to oxygen gas and supply it to an ozone generator.
[0006]
For this reason, no clear cause has been elucidated so far, and it is difficult to eliminate the additive gas.
[0007]
[Problems to be solved by the invention]
By the way, recently, by using a coplanar structure creeping discharge, 300 (g / Nm^Three) It has become possible to generate ozone with an extremely high concentration as described above.
[0008]
However, as in the case of the conventional example described above, the concentration of the generated ozone greatly fluctuates due to a very small amount of nitrogen gas component or carbon dioxide component contained in the oxygen gas that is the ozone source gas.
[0009]
An object of the present invention is to provide a compact, inexpensive, highly reliable and stable ozone generator capable of preventing the generated ozone concentration from fluctuating due to an additive gas component to the ozone source gas. It is in.
[0010]
[Means for Solving the Problems]
  To achieve the above object, the invention corresponding to claim 1 includes a dielectric layer covering the pair of electrodes, and an AC voltage is applied between the pair of electrodes to discharge the surface of the dielectric layer. In an ozone generator that generates ozone from ozone source gas that fills the space between the paired electrodes,The dielectric layer material contains 10 to 90 weight percent (wt%) of bismuth oxide, 10 to 90 weight percent (wt%) of zinc oxide, and 0 to 40 weight percent (wt%) of lead oxide. Use the one having the composition.
[0014]
  Meanwhile, claims2In the invention corresponding to the above, a pair of electrodes provided on the substrate and a dielectric layer that covers the pair of electrodes are provided, and an AC voltage is applied between the pair of electrodes to apply to the surface of the dielectric layer. In an ozone generator that generates ozone from ozone source gas that fills the space between electrodes that form a discharge, 10 to 90 weight percent (wt%) of bismuth oxide and zinc oxide are used as the dielectric layer material. A material containing 10 to 90 percent by weight (wt%) and a lead oxide content of 0 to 40 percent by weight (wt%) is used.
[0015]
  Therefore, the claims1, 2In the ozone generator according to the invention, the dielectric layer material contains 10 to 90 weight percent (wt%) of bismuth oxide, 10 to 90 weight percent (wt%) of zinc oxide, and contains lead oxide. By using a material having an amount of 0 to 40 weight percent (wt%), it is possible to suppress the ozonolysis reaction on the surface of the dielectric layer and to generate extremely stable high-concentration ozone.
  Further, since the power density is increased and a higher ozone yield can be secured with the same power, the power supply for applying the AC voltage can be reduced in size, and the entire apparatus can be made compact.
  Furthermore, since it is not necessary to add an additive gas to the ozone source gas in order to generate high-concentration ozone, a device for adding the additive gas is not required, the entire device is simplified, and the device is inexpensive and highly reliable. Can be obtained.
  On the other hand, there is a semiconductor process as one of the ozone application fields, and there is a case where nitrogen gas mixing is disliked in chemical reaction processes such as ozone ashing and oxide film deposition. Therefore, it can be optimally used for the above-mentioned use.
  In addition, since the magnitude of the applied voltage from the AC voltage application power source can be reduced, abnormal discharge at the wiring extraction part etc.FearAs a result, reliability can be improved.
  Furthermore, since the linear expansion coefficients of the substrate and the dielectric layer can be made substantially the same, the cooling efficiency can be increased by bringing the substrate and the cooling plate into close contact with each other.
[0016]
  Claims3In the invention corresponding to the above-mentioned claim,2In the ozone generator according to the invention, the substrate is made of soda glass or a material having a linear expansion coefficient substantially equal to that of the soda glass, and the dielectric layer is made of bismuth oxide at 20 to 30 weight percent ( wt%), 30 to 40 weight percent (wt%) of zinc oxide, 15 to 25 weight percent (wt%) of boron oxide, and 0 to 10 weight percent (wt%) of silicon oxide.
[0017]
  Therefore, the claims3In the ozone generator of the invention corresponding to the above, the substrate is made of soda glass or a material having a linear expansion coefficient substantially equal to that of soda glass, and bismuth oxide is 20 to 30 weight percent ( wt%), 30 to 40 weight percent (wt%) of zinc oxide, 15 to 25 weight percent (wt%) of boron oxide, and 0 to 10 weight percent (wt%) of silicon oxide. The above-mentioned claim2The effect similar to that of the invention corresponding to the above can be remarkably exhibited more effectively.
[0020]
  Claims4In the invention corresponding to the above-mentioned claim,1 orClaim2In the ozone generating device according to the invention, a powder layer of powder containing silicon oxide or zinc oxide is provided on the dielectric layer.
[0021]
  Therefore, the claims4In the ozone generator of the invention corresponding to the above, by providing a powder layer on the dielectric layer, extremely stable high-concentration ozone can be generated.OrClaim2The same operation as that of the invention corresponding to each of the above can be performed simultaneously. Further, by using a powder containing silicon oxide or zinc oxide as the powder of the powder layer, the above action can be more effectively and remarkably exhibited.
[0022]
  And claims5In the invention corresponding to the above-mentioned claim,4In the ozone generator of the invention corresponding to the above, the particle size of the powder in the powder layer is 10 micrometers (μm) or less.
[0023]
  Therefore, the claims5In the ozone generator of the invention corresponding to the above, the particle size of the powder of the powder layer is 10 micrometers (μm) or less to form a homogeneous layer,4The effect similar to that of the invention corresponding to the above can be remarkably exhibited more effectively.
[0028]
  Claims6In the invention corresponding to the above,OrClaim2In the ozone generator of the invention corresponding to the above, formed on the dielectric layer by the resinate methodContains silicon oxide or zinc oxideA thin film layer is provided.
[0029]
  Therefore, the claims6In the ozone generator of the invention corresponding to the above, it is formed on the dielectric layer by the resinate method.Contains silicon oxide or zinc oxideBy providing the thin film layer, the ozone decomposition reaction on the surface of the dielectric layer can be suppressed, and extremely stable high concentration ozone can be generated.OrClaim2The same operation as that of the invention corresponding to each of the above can be performed simultaneously.
[0030]
  And claims7In the invention corresponding to the above-mentioned claim,6In the ozone generator of the invention corresponding to the above, a thin film layer containing silicon oxide or zinc oxide is used.
[0031]
  Therefore, the claims7In the ozone generator of the invention corresponding to the above-mentioned claim, the thin film layer contains silicon oxide or zinc oxide.6The effect similar to that of the invention corresponding to the above can be remarkably exhibited more effectively.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, an ozone raw material is provided that has a dielectric layer covering the pair of electrodes, applies an AC voltage between the pair of electrodes to generate a discharge on the surface of the dielectric layer, and fills the space between the pair of electrodes. In a creeping discharge or volume discharge type ozone generator that generates ozone from gas, the material of the collision surface of ozone molecules in the dielectric layer has an ozone decomposition probability of 7 × 10 due to collision between the dielectric layer and ozone molecules.^-6By making the following conditions, the decomposition reaction that ozone returns to oxygen due to collision between the dielectric layer and ozone molecules, that is, the ozone decomposition reaction on the surface of the dielectric layer is suppressed, and extremely stable high-concentration ozone is generated. The basic gist is to make it possible.
Hereinafter, embodiments of the present invention based on the above-described concept will be described in detail with reference to the drawings.
[0033]
(First embodiment)
FIG. 1 is a schematic diagram showing a configuration example of a creeping discharge type ozone generator according to the present embodiment, and FIG. 2 is a schematic diagram showing a configuration example of an ozone generating electrode plate in the ozone generator.
[0034]
1 and 2, a substrate 1 made of glass (for example, soda glass) and a plurality of pairs provided by printing a conductive material such as silver paste on the surface of the substrate 1 by, for example, screen printing or the like. An ozone generating electrode plate is composed of the electrodes 2 and 3 and the dielectric layer 4 covering the plurality of pairs of electrodes 2 and 3.
[0035]
Here, the dielectric layer 4 of the ozone generating electrode plate contains 10 to 90 percent by weight (wt%) of bismuth oxide, 10 to 90 percent by weight (wt%) of zinc oxide, and contains lead oxide. Those having a composition of 0 to 40 weight percent (wt%) are used.
[0036]
Particularly preferably, bismuth oxide is 20-30 weight percent (wt%), zinc oxide is 30-40 weight percent (wt%), boron oxide is 15-25 weight percent (wt%), and silicon oxide is 0-10. A composition containing a weight percent (wt%) is preferred.
[0037]
On the other hand, on the back side of the substrate 1, a cooling plate 6 made of metal cooled by the cooling water 5 is provided in close contact with the substrate 1.
[0038]
Further, an external AC power supply 8 for applying a high AC voltage is connected to the plurality of pairs of electrodes 2 and 3 through wiring 7.
[0039]
Further, a gas guide 9 is provided on the surface of the substrate 1 on the electrodes 2 and 3 side, and an ozone source gas (for example, oxygen gas) 10 is supplied from the outside into a space between the plurality of pairs of electrodes 2 and 3. It is introduced to fill the space.
[0040]
Then, a high AC voltage is applied from the AC power supply 8 between the plurality of pairs of electrodes 2 and 3 to generate a creeping discharge 11 on the surface of the dielectric layer 4. Ozone 12 is generated.
[0041]
FIGS. 3A and 3B are a plan view and a side sectional view showing a specific mounting configuration example of the creeping discharge type ozone generator according to the present embodiment, and are the same as those in FIGS. Are denoted by the same reference numerals.
[0042]
As shown in FIG. 3, the ozone generator includes a plurality of pairs of electrodes 2 and 3, a cooling plate 6 made of metal cooled by cooling water 5, and an ozone source gas (for example, oxygen gas) 10. A gas guide 9 introduced into a space between a plurality of pairs of electrodes 2, 3, a spacer 21, a case 22 for storing them, and a pair of power supply terminals 23 attached to the case 22. doing.
[0043]
FIG. 4 is a schematic diagram showing a specific example of the overall mounting configuration of the creeping discharge type ozone generator according to the present embodiment, and the same elements as those in FIGS. 1 to 3 are denoted by the same reference numerals. .
[0044]
In FIG. 4, the ozone generator main body 31 having the configuration shown in FIGS. 1 to 3 is connected to a pair of power supply terminals 23 with a power supply 8 for applying an AC voltage via a wiring 7. ing.
[0045]
The ozone generator body 31 is supplied with oxygen gas, which is the ozone raw material gas 10, from an oxygen cylinder 33 through a pressure reducing valve 34 and an oxygen flow meter 35.
[0046]
Further, the ozone generator main body 31 is supplied with nitrogen gas as an additive gas to the ozone raw material gas 10 from the nitrogen cylinder 36 through the pressure reducing valve 37 and the nitrogen flow meter 38 as necessary. (In the figure, it is shown for convenience of explanation).
[0047]
Furthermore, the ozone 12 generated by the ozone generator main body 31 is taken out from the ozone take-out part 41 through the ozone flow meter 39 and the pressure reducing valve 40.
[0048]
Next, the operation of the creeping discharge type ozone generator of the present embodiment configured as described above will be described.
[0049]
In the ozone generating apparatus to which the ozone generating electrode plate of the present embodiment is applied, a plurality of pairs of electrodes 2 and 3 are covered with the dielectric layer 4, so that the surfaces of the electrodes 2 and 3 are exposed to the creeping discharge 11. It is not exposed directly, and there is no spatter deterioration and a long life is obtained.
[0050]
In the creeping discharge 11, electrons e generated by the discharge are oxygen molecules O.₂Is dissociated to generate oxygen atoms O. Further, this oxygen atom O is another oxygen molecule O.₂Combined with ozone O_ThreeWill occur.
[0051]
e + O₂    → e + O + O (1)
O + O₂+ O₂    → O_Three+ O₂    (2)
In creeping discharge 11, ozone O_ThreeTo oxygen molecule O₂The reverse reaction to
[0052]
e + O_Three    → e + O + O₂        ...... (3)
O + O_Three    → O₂+ O₂          ...... (4)
The reaction formula in the creeping discharge 11 is represented by the formula (4), and this is the same as the volume discharge which is a barrier discharge adopted in the conventional ozone generator.
[0053]
However, the ozone generator of the present embodiment generates a discharge in a very small space near the surface of the dielectric layer 4, that is, the creeping discharge 11, and the electrons and oxygen during the discharge to the surface of the dielectric layer 4. Radical collisions with atoms occur violently. for that reason,
O + O_Three+ Wall → O₂Ten O₂+ Wall ...... (5)
e + O_Three+ Wall → e + O + O₂+ Wall ...... (6)
Such a reaction occurs more remarkably than the conventional ozone generator.
[0054]
This reaction is a kind of catalytic reaction on the surface of the dielectric layer 4 (wall: wall surface)._ThreeDecomposition will occur violently.
[0055]
Such a reaction rate varies greatly depending on the surface material of the dielectric layer 4 because it is a catalytic reaction.
[0056]
In this case, the decomposition of ozone due to the collision with the surface of the dielectric layer 4, that is, the collision surface (wall surface) of ozone molecules can be considered as follows.
[0057]
That is, first, as shown in FIG. 5, a space sandwiched between upper and lower walls of a unit area is considered. One of the walls is an electrode and the other is a gas guide or another electrode.
[0058]
The average velocity of gas molecules in thermal motion follows the Maxell distribution,
[Expression 1]

Where k is the Boltzmann constant [1.38 × 10^-16erg / K], T represents the gas temperature [K], and m represents the mass [g] of one gas molecule.
[0059]
The mass of ozone is 48 [g] per mol, so the mass per molecule m_O3Is
[Expression 2]

For example, at the gas temperature T = 300 [K], the velocity of ozone molecules is
[Equation 3]

Next, considering a unit volume space as shown in FIG.
[0060]
1cm wall²Collision frequency f_wall[cm^-2s^-1] Ignores collisions with other gas molecules
[Expression 4]

It becomes.
[0061]
The reason for the factor 1/4 is that some molecules are directed in the opposite direction to those facing the wall surface, so n / 2, and the average of the vertical component on the wall surface is 1/2.
[0062]
For example, if the ozone concentration is 15% at atmospheric pressure, the ozone number density n_O3Is
[Equation 5]

So collision frequency f_O3-wallIs
[Formula 6]

Of the ozone molecules that collide with the wall, z_wallIt is assumed that decomposition occurs with the probability of
[0063]
Ozone that does not decompose will bounce off the wall. This reflectance R is defined by the following equation.
[0064]
[Expression 7]

  The rate at which the ozone number density per unit volume [03] decomposes on the wall surface is per second.
[Equation 8]

It is represented by
[0065]
h_chIs 0.06 [cm] (= 0.6mm), z_wallIs 1.0 × 10^-6Even with such a small value, the decrease rate of ozone number density is per second.
[Equation 9]

It is.
[0066]
The amount of ozone generated is the dissociation efficiency due to electron collision of oxygen molecules. The typical electric field strength within the ozone generator is 100 to 200 [Td].
[Expression 10]

It is.
[0067]
If 100% of dissociated oxygen atoms become ozone, two ozone atoms are generated from one oxygen molecule.
[0068]
Energy branch to electrons be = 0.38, power 6.6 [W / cm^Three]
## EQU11 ##

Therefore, comparing the above equations (15) and (17), it can be seen that the decomposition at the wall surface reaches 20% of the occurrence.
[0069]
As described above, by changing the surface material of the dielectric layer 4, the ozone decomposition probability z due to the collision with the wall surface that is the ozone molecule collision surface in the dielectric layer 4._wallWill change.
[0070]
In the present embodiment, as a result of trying various substances for such a reaction that has not been known in the past, the material of the dielectric layer 4 suitable for generating ultra-high-concentration ozone is used as the ozone generating electrode constituting the ozone generating device. Applies to plates.
[0071]
Incidentally, the dielectric layer 4 generally needs to be tightly bonded to the substrate 1 made of glass.
[0072]
This is because if there is no tight bonding with the substrate 1, there will be a gap between the dielectric layer 4 and the substrate 1, and dielectric breakdown will occur between the electrodes 2 and 3 via this gap. Cannot be generated.
[0073]
In order to tightly bond them, the linear expansion coefficient of the dielectric layer 4 needs to substantially match the linear expansion coefficient of the substrate 1 made of glass.
[0074]
As the substrate 1, soda glass is industrially most easily available in terms of quantity and cost. Soda glass has a linear expansion coefficient of 70 to 100 × 10.^-7And it shows a large value in glass. Therefore, so-called lead glass containing 40 wt% (weight percent) or more of lead oxide is usually used as the dielectric layer 4.
[0075]
The lead glass is used as the dielectric layer 4 and the ozone source gas 10 is introduced into the creeping discharge type ozone generator of this embodiment as pure oxygen gas containing oxygen of 99.9% or more.
[0076]
Then, under such a state (a state in which the substrate 1 is made of soda glass and the dielectric layer 4 is lead glass), a high alternating voltage is applied from the alternating current power source 9 to the electrodes 2 and 3, and the surface of the dielectric layer 4 A creeping discharge 11 is generated, and ozone 12 is generated from the ozone source gas 10 by the creeping discharge 11.
[0077]
FIG. 7 is a characteristic diagram showing ozone generation characteristics when bismuth glass and lead oxide are used as the dielectric layer 4, and the lead oxide in this figure is so-called lead glass.
[0078]
In FIG. 7, the horizontal axis represents the ozone concentration, that is, the number of ozone grams per unit cubic meter volume in the standard state (0 degree Celsius, 1 atm), and the vertical axis represents the ozone yield, that is, the unit electric energy in kilowatt hours. It represents the number of grams that is the amount of ozone that can be generated per hit.
[0079]
The maximum ozone concentration is 10 g / Nm^ThreeThe ozone yield is 10 g / kWh or less at maximum. This is a maximum ozone concentration of 200 g / Nm produced by a volume discharge type ozone generator conventionally used for industrial use.^ThreeCompared with the maximum ozone yield of 140 g / kWh, it is very small and impractical.
[0080]
Therefore, when the so-called bismuth glass having a linear expansion coefficient that matches the soda glass that is the material of the substrate 1 is used as the material of the dielectric layer 4 and the lead oxide content is suppressed to 40 wt% or less, extremely high ozone Generation characteristics can be obtained.
[0081]
As shown in FIG. 7, when the bismuth glass is used as the dielectric layer 4, both the ozone concentration and the ozone yield can be extremely high compared with the case where lead oxide is used. It is.
[0082]
This is because the reaction shown in the above formulas (5) and (6) does not occur on the bismuth glass surface.
[0083]
As the composition of this bismuth glass, the lead oxide content is suppressed to 0 to 40 weight percent (wt%), and the remaining materials are 10 to 90 weight percent (wt%) of bismuth oxide and 10 to 90 weight of zinc oxide. By containing a percentage (wt%), it is possible to obtain a linear expansion coefficient that substantially matches the soda glass that is the substrate 1.
[0084]
Specifically, zinc oxide is 30 to 40 weight percent (wt%), bismuth oxide is 20 to 30 weight percent (wt%), boron oxide is 15 to 25 weight percent (wt%), and silicon oxide is 0 to 10 weight percent ( wt%), the linear expansion coefficient with the soda glass as the substrate 1 is completely matched.
[0085]
As a result, the dielectric layer 4 is in close contact with the substrate 1 so that no gap is formed between the electrodes 2 and 3, high insulation can be obtained, and stable high-concentration ozone can be generated.
[0086]
On the other hand, since the power density is increased and a higher ozone yield can be secured with the same power, the AC voltage application power source 8 can be miniaturized and the entire apparatus can be made compact.
[0087]
Further, since it is not necessary to add an additive gas to the ozone source gas 10 in order to generate high-concentration ozone, an additive gas addition device (from the nitrogen cylinder 36, the pressure reducing valve 37, and the nitrogen flow meter 38) is unnecessary. Thus, the entire apparatus can be simplified, and an inexpensive and highly reliable apparatus can be obtained.
[0088]
Furthermore, there is a semiconductor process as one of the ozone application fields, and there is a case where it is hated to mix nitrogen gas in a chemical reaction process such as ozone ashing or oxide film deposition, but this ozone generator does not mix nitrogen gas as an additive gas. Therefore, it can be optimally used for the above-mentioned use.
[0089]
Further, since the magnitude of the applied voltage from the power supply 8 for applying AC voltage can be reduced, there is no fear of abnormal discharge at the extraction portion of the wiring 7 and the reliability can be improved as a result.
[0090]
Furthermore, since the linear expansion coefficients of the substrate 1 and the dielectric layer 4 can be made substantially the same, the substrate 1 and the cooling plate 6 can be brought into close contact with each other to increase the cooling efficiency.
[0091]
As described above, in the creeping discharge type ozone generator of the present embodiment, bismuth oxide is used as the material of the dielectric layer 4 covering the paired electrodes 2 and 3 provided on the substrate 1. Since 90% by weight (wt%), 10 to 90% by weight (wt%) of zinc oxide and a lead oxide content of 0 to 40% by weight (wt%) are used. In addition, it is possible to suppress the ozone decomposition reaction on the surface of the dielectric layer 4 and to generate extremely stable high-concentration ozone.
[0092]
In addition, since at least silicon oxide and zinc oxide that are chemically stable are used as the dielectric layer 4, the above effects can be more effectively and remarkably exhibited.
[0093]
These characteristics indicate the decomposition probability z at the surface of ozone._wallWe have found for the first time that this is due to different materials.
[0094]
FIG. 8 shows the ozone decomposition probability z with respect to the characteristics of zinc oxide and bismuth glass._wallIt is a characteristic view which converts and shows the value of.
[0095]
In FIG. 8, the vertical axis represents the ozone concentration C, and the horizontal axis represents the characteristic energy W / Q.
[0096]
15 × 10 against zinc oxide^-7, 30 × 10 against bismuth^-7It is. These values are sufficient characteristics as an ozone generator.
[0097]
Figure 9 shows the ozone decomposition probability z on the horizontal axis._wall FIG. 5 is a characteristic diagram showing the saturated ozone concentration Cs on the vertical axis.
[0098]
As shown in FIG. 9, as the dielectric layer 4, the material of the collision surface of the ozone molecule in the dielectric layer 4 is an ozone decomposition probability z due to the collision between the dielectric layer 4 and the ozone molecule._wallIs 7 × 10^-6By making the following, it becomes possible to obtain high ozone generation characteristics.
[0099]
That is, in this case, as shown in FIG._wallIs 7 × 10^-6By achieving the following, it is possible to achieve the intended purpose for the time being, that is, it is possible to generate high-concentration ozone that is more stable than in the past. For example, when bismuth glass is used, FIG. As shown, the saturated ozone concentration Cs is at least 250 g / Nm^-3As long as the above can be secured, as shown in FIG. 8, the ozone concentration Cs is 300 g / Nm.^-3Considering that it is possible to generate more stable high-concentration ozone by ensuring the above, the ozone decomposition probability z_wallIs 7 × 10^-6 It is more preferable to set a smaller value from 1.
[0100]
Furthermore, since the power density is increased and a higher ozone yield can be secured with the same power, the AC voltage application power source 8 can be miniaturized and the entire apparatus can be made compact.
[0101]
Furthermore, since it is not necessary to add an additive gas to the ozone source gas 10 in order to generate high-concentration ozone, a device for additive gas addition, which has been essential in the past, is unnecessary, simplifying the entire device, An inexpensive and highly reliable device can be obtained.
[0102]
On the other hand, there is a semiconductor process as one of the ozone application fields, and there is a case in which nitrogen gas mixing is disliked in a chemical reaction process such as ozone ashing or oxide film deposition. In the ozone generator of this embodiment, nitrogen gas is added. Since it does not need to be mixed as a gas, it can be optimally used for the above-mentioned use.
[0103]
Further, since the magnitude of the applied voltage from the power supply 8 for applying the alternating voltage can be reduced, there is no fear of abnormal discharge at the extraction portion of the wiring 7 and the reliability can be improved as a result.
[0104]
Furthermore, since the linear expansion coefficients of the substrate 1 and the dielectric layer 4 can be made substantially the same, the substrate 1 and the cooling plate 6 can be brought into close contact with each other to increase the cooling efficiency.
[0105]
(Second Embodiment)
FIG. 10 is a schematic diagram showing a configuration example of the ozone generating electrode plate in the creeping discharge type ozone generator according to the present embodiment. The same parts as those in FIG. Only the different parts are described here.
[0106]
That is, the ozone generating electrode plate of the present embodiment has a configuration in which a powder layer 13 is provided on the dielectric layer 4 as shown in FIG.
[0107]
Here, the powder layer 13 has a powder particle size of 10 micrometers (μm) or less.
[0108]
The powder layer 13 uses silicon oxide and zinc oxide as powder.
[0109]
In the creeping discharge type ozone generator of the present embodiment configured as described above, the powder layer 13 is provided on the dielectric layer 4, and the particle size of the powder of the powder layer 13 is 10 micrometers (μm). By making the following, a homogeneous powder layer 13 can be obtained, and the dielectric layer 4 is not directly exposed to the creeping discharge 11. Therefore, even if lead glass is used, the ozone generation characteristics are not affected. Is greatly influenced by the composition of the powder layer 13.
[0110]
In FIG. 11, silicon oxide, bismuth glass, zinc oxide, alumina, titania, and lead oxide are used as the powder layer 13, the ozone source gas 10 is pure oxygen gas containing 99.9% or more of oxygen, 6 is a graph showing ozone generation characteristics when a high AC voltage is applied from an AC power source 9 to generate a creeping discharge 11 on the surface of the dielectric layer 4 and ozone 12 is generated from the ozone source gas 10 by the creeping discharge 11. .
[0111]
As shown in FIG. 11, when silicon oxide, bismuth glass, and zinc oxide are used as the powder layer 13, both the ozone concentration and the ozone yield are very high.
[0112]
In contrast, when lead oxide is used as the powder layer 13, the ozone concentration is zero, and the performance as an ozone generator cannot be obtained.
[0113]
When alumina and titania are used as the powder layer 13, the ozone concentration is 20 to 100 g / Nm.^ThreeThe fluctuation is so severe that stable operation cannot be obtained.
[0114]
This suggests that the decomposition reaction at the surface of ozone is associated with catalysis.
[0115]
It is a well-known fact that titania itself is used as a catalyst because it has a characteristic that its crystallinity is easily changed.
[0116]
Alumina has no example of using itself as a catalyst, but it is also a well-known fact that platinum or the like has a catalytic action when supported on the alumina surface.
[0117]
Although not shown here, the same applies to zirconia and the like.
[0118]
Thus, in order to suppress the surface reaction, when a substance that is not used as a catalyst is used as the powder layer 13, high ozone generation characteristics can be obtained.
[0119]
FIG. 12 is a characteristic diagram showing the ozone generation characteristics when 1% nitrogen gas is added to 99% oxygen gas as the ozone source gas 10. The other conditions are the same as described above.
As shown in FIG. 12, ozone generation characteristics are all good for substances other than lead oxide. When ozone source gas 10 containing a small amount of nitrogen gas is exposed to creeping discharge 11, electrons e and nitrogen molecules N in the discharge are discharged.₂Nitrogen atom N is generated by the collision.
[0120]
e + N₂    → e + N + N (18)
further,
N + O₂    → NO + O (19)
NO + O_Three    → NO₂+ O₂      ...... (20)
NO₂+ O_Three    → NO_Three+ O₂    (21)
NO₂+ NO_Three    → N₂O_Five      ...... (22)
Nitrogen oxides (NO, NO₂, NO_Three, N₂O_Five) Is generated.
[0121]
Such a nitrogen oxide has a strong adsorptivity to a substance and is easily attached to the surface of the powder layer 13.
[0122]
Ozone decomposition probability z_wallIs the probability of ozone colliding with a site that contributes to ozonolysis among molecular bonds like the surface. Oxygen decomposition probability z due to nitrogen oxides adhering to such decomposition sites_wallBecomes smaller.
[0123]
As a result, nitrogen oxide is attached to the surface that causes catalytic action such as titania or alumina that has caused a reaction to decompose ozone, and the catalytic action is hindered so that high ozone generation characteristics can be obtained.
[0124]
Titania and alumina require an additive gas such as a small amount of nitrogen gas as described above, and exhibit extremely sensitive characteristics to the amount of additive gas.
[0125]
Therefore, by using silicon oxide and zinc oxide exhibiting stable operation as the powder layer 13, good ozone generation characteristics can be obtained.
[0126]
As described above, in the creeping discharge type ozone generator of the present embodiment, the particle size is 10 μm on the dielectric layer 4 covering the paired electrodes 2 and 3 provided on the substrate 1. Since the powder layer 13 of powder of a meter (μm) or less is provided, it is possible to suppress the ozonolysis reaction on the surface of the dielectric layer 4 and to generate extremely stable high-concentration ozone.
[0127]
Furthermore, since the chemically stable silicon oxide and zinc oxide are used as the powder of the powder layer 13, the above effect can be more effectively and remarkably exhibited.
[0128]
(Third embodiment)
FIG. 13 is a schematic diagram showing a configuration example of an ozone generating electrode plate in the creeping discharge type ozone generator according to the present embodiment, where the same parts as those in FIG. Only the different parts are described here.
[0129]
That is, the ozone generating electrode plate of the present embodiment has a configuration in which a thin film layer 14 of about 1 micrometer (μm) is provided on the dielectric layer 4 as shown in FIG.
[0130]
Here, the thin film layer 14 is formed by, for example, a resinate method, and one containing silicon oxide or zinc oxide is used.
[0131]
In the creeping discharge type ozone generator of the present embodiment configured as described above, the dielectric layer 4 has a creeping surface by providing the thin film layer 14 formed by the resinate method on the dielectric layer 4. It will not be directly exposed to the discharge 11. The degree of influence depends on the composition of the thin film layer 14.
[0132]
With regard to this composition, it is possible to obtain good ozone generation characteristics by using, as the thin film layer 14, silicon oxide and zinc oxide, which have good characteristics in the powder layer 13 described above.
Furthermore, since the thin film layer 14 is extremely thin, even if the linear expansion coefficient is different from that of the substrate 1 and the dielectric layer 4, the thin film layer 14 is not peeled off and stable characteristics can be obtained.
[0133]
As described above, the creeping discharge type ozone generator of the present embodiment is formed by the resinate method on the dielectric layer 4 covering the paired electrodes 2 and 3 provided on the substrate 1. Since the thin film layer 14 is provided, the ozone decomposition reaction on the surface of the dielectric layer 4 can be suppressed and extremely stable high-concentration ozone can be generated.
[0134]
Furthermore, since the chemically stable silicon oxide and zinc oxide are used as the thin film layer 14, the above effect can be more effectively and remarkably exhibited.
[0135]
(Other embodiments)
(A) It is good also as a structure which provides the powder layer 13 of 2nd Embodiment mentioned above on the dielectric material layer 4 in 1st Embodiment mentioned above.
[0136]
In this case, it is possible to obtain the same operational effects as the first embodiment and the second embodiment at the same time.
[0137]
(B) The thin film layer 14 of the third embodiment described above may be formed on the dielectric layer 4 of the first embodiment described above.
[0138]
In this case, it is possible to obtain the same operational effects as the first embodiment and the third embodiment at the same time.
[0139]
(C) In each of the above-described embodiments, the case where the present invention is applied to a creeping discharge type ozone generator that generates ozone using creeping discharge has been described. However, the present invention is not limited thereto, and for example, a pair of electrodes 2 , 3, the present invention can be applied to a volume discharge type ozone generator that generates ozone by using silent discharge, that is, volume discharge.
[0140]
FIG. 14 is a schematic diagram showing a configuration example of a coaxial cylindrical ozonizer which is a typical example of a volume discharge type ozone generator according to the present embodiment, and the same elements as those in FIG.
[0141]
In FIG. 14, a glass tube 43 is inserted inside the stainless tube 42. In addition, a metal layer 44 is provided on the inner surface of the glass tube 43, and by applying a high voltage to the metal layer 44, a volume discharge 45 is generated in the space between the stainless steel tube 42 and the glass tube 43.
[0142]
The heat generated by this discharge is cooled by the cooling water 46.
[0143]
Oxygen gas, which is the source gas 47, becomes ozone 48 by volume discharge and is discharged outside.
[0144]
FIG. 15 is a characteristic diagram showing the ozone generation characteristics of the coaxial cylindrical ozonizer.
[0145]
In FIG. 15, the vertical axis represents the ozone concentration C, and the horizontal axis represents the characteristic energy W / Q. The gas is 99.9% oxygen.
[0146]
Also in this case, the ozone decomposition probability z of the wall_wall1.2 × 10^-6By making it a smaller value from the above, it is possible to improve the ozone generation characteristics.
[0147]
In particular, high characteristics cannot be obtained at about 7 × 10 −6, and the contents of the present invention as described above can be applied by setting values higher than this.
[0148]
As described above, even with the ozone generator of the present embodiment, it is possible to obtain the same operational effects as those of the ozone generators of the first to third embodiments described above.
[0149]
【The invention's effect】
As described above, according to the present invention, ozone generation that is compact, inexpensive, and highly reliable and stable can prevent the generated ozone concentration from fluctuating due to the additive gas component to the ozone source gas. A device can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a first embodiment of a creeping discharge type ozone generator according to the present invention.
FIG. 2 is a schematic diagram showing a configuration example of an ozone generation electrode plate in the ozone generation apparatus according to the first embodiment.
FIGS. 3A and 3B are a plan view and a side sectional view showing a specific mounting configuration example of the ozone generator according to the first embodiment. FIGS.
FIG. 4 is a schematic diagram showing a specific example of the entire mounting configuration of the ozone generator according to the first embodiment.
FIG. 5 is a conceptual diagram for explaining operational effects of the ozone generator according to the first embodiment.
FIG. 6 is a conceptual diagram for explaining operational effects of the ozone generator according to the first embodiment.
FIG. 7 is a characteristic diagram for explaining the function and effect of the ozone generation electrode plate in the ozone generation apparatus according to the first embodiment;
FIG. 8 is a characteristic diagram for explaining operational effects in the ozone generator according to the first embodiment;
FIG. 9 is a characteristic diagram for explaining operational effects in the ozone generator according to the first embodiment;
FIG. 10 is a schematic diagram showing a configuration example of an ozone generation electrode plate in an ozone generation apparatus according to a second embodiment of the present invention.
FIG. 11 is a characteristic diagram for explaining the function and effect of the ozone generation electrode plate in the ozone generation apparatus according to the second embodiment.
FIG. 12 is a characteristic diagram for explaining the function and effect of the ozone generating electrode plate in the ozone generating apparatus according to the second embodiment.
FIG. 13 is a schematic diagram showing a configuration example of an ozone generation electrode plate in an ozone generation apparatus according to a third embodiment of the present invention.
FIG. 14 is a schematic view showing another embodiment of a creeping discharge type ozone generator according to the present invention.
FIG. 15 is a characteristic diagram for explaining operational effects of the ozone generator according to the other embodiment.
[Explanation of symbols]
1 ... Board
2, 3 ... Electrodes
4 ... Dielectric layer
5 ... Cooling water
6 ... Cooling plate
7 ... Wiring
8 ... AC power supply
9. Gas guide
10 ... Ozone raw material gas (oxygen gas)
11 ... Creepage discharge
12 ... Ozone
13 ... powder layer
14 ... Thin film layer
21 ... Spacer
22 ... Case
23 ... Terminal for power supply
31 ... Ozone generator body
33 ... oxygen cylinder
34 ... Pressure reducing valve
35 ... Oxygen flow meter
36 ... Nitrogen cylinder
37 ... Pressure reducing valve
38 ... Nitrogen flow meter
39 ... Ozone flow meter
40 ... Pressure reducing valve
41 ... Ozone extraction part
42 ... Stainless steel pipe
43 ... Glass tube
44 ... Metal layer
45 ... Volume discharge
46 ... Cooling water
47 ... Raw gas
48 ... Ozone.

Claims (7)

Ozone source gas comprising a dielectric layer covering the paired electrodes, applying an AC voltage between the paired electrodes to generate a discharge on the surface of the dielectric layer, and filling a space between the paired electrodes In the ozone generator that generates ozone from
As the material of the dielectric layer, 10 to 90 weight percent (wt%) of bismuth oxide, 10 to 90 weight percent (wt%) of zinc oxide, and 0 to 40 weight percent (wt%) of lead oxide. The ozone generator characterized by using the composition having the following composition . A pair of electrodes provided on a substrate and a dielectric layer covering the pair of electrodes are provided, and an AC voltage is applied between the pair of electrodes to generate a discharge on the surface of the dielectric layer. In the ozone generator for generating ozone from the ozone source gas that fills the space between the pair of electrodes,
As the material of the dielectric layer, 10 to 90 weight percent (wt%) of bismuth oxide, 10 to 90 weight percent (wt%) of zinc oxide, and 0 to 40 weight percent (wt%) of lead oxide. The ozone generator characterized by using the composition having the following composition . In the ozone generator according to claim 2 ,
As the substrate, composed of soda glass, or a material having a linear expansion coefficient substantially equivalent to the soda glass,
As the material of the dielectric layer, bismuth oxide is 20 to 30 weight percent (wt%), zinc oxide is 30 to 40 weight percent (wt%), boron oxide is 15 to 25 weight percent (wt%), and silicon oxide is used. An ozone generator characterized by having a composition containing 0 to 10 weight percent (wt%) . In the ozone generator of Claim 1 or Claim 2 ,
An ozone generator characterized in that a powder layer of powder containing silicon oxide or zinc oxide is provided on the dielectric layer . In the ozone generator of Claim 4 ,
An ozone generator, wherein the powder layer has a powder particle size of 10 micrometers (μm) or less . In the ozone generator of Claim 1 or Claim 2 ,
An ozone generator characterized in that a thin film layer containing silicon oxide or zinc oxide formed by a resinate method is provided on the dielectric layer . The ozone generator according to claim 6, wherein
An ozone generator using silicon oxide or zinc oxide as the thin film layer .

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