JP2004190892A - Fluid purifying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid purifying device enabling stable supply of highly purified fluid over a long period by maximizing the adsorbing capability of an adsorbent filter to be used in the fluid purifying device. <P>SOLUTION: The fluid purifying device comprises a photocatalytic unit 2 for decomposing contaminants in the fluid to be treated and an adsorbent filter unit 3 for adsorbing the contaminants in the fluid. The photocatalytic unit 2 is arranged on the upstream side of the adsorbent filter unit 3 in the flowing direction of the fluid. A dust removing filter unit 9 is arranged on the downstream side of the adsorbent filter unit. Change-over means 11, 12, 13, 14 selectively introduce the fluid to be treated into the photocatalytic unit or the adsorbent unit for further improved effects. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００２８】
【表２】

【００２９】
表１は、吸着開始時の吸着剤フィルタの吸着性能を示している。この表に示した各汚染物質分子は、いずれも吸着剤フィルタにより吸着保持される。表２は、吸着が進行し、飽和に近くなったときの吸着性を示している。表の一番左側の欄の化合物は吸着剤フィルタに捕捉されず、通過し始める。これらは比較的分子量の小さい化合物である。表の左から２番目と３番目の欄の化合物は、吸着されるが後に脱離して吸着剤フィルタから漏出してくることがある。表の一番右の欄の化合物は、脱着することなしに吸着剤に吸着保持されたままとなる。これらは比較的分子量の大きい化合物である。（表１，２において、Ｄ２〜Ｄ６は基本構成単位−Ｓｉ（ＣＨ_３）_２Ｏ−がそれぞれ２〜６個のシリコーン化合物、ＭＥＫはメチルエチルケトン、ＩＰＡはイソプロピルアルコール、ＰＧＭＥＡはプロピレングリコールモノメチルエーテルアセテート、ＰＧＭＥはプロピレングリコールモノメチルエーテル、ＮＭＰはＮ−メチルピロリドン、ＤＢＰはフタル酸ジブチル、ＤＯＰはフタル酸ジオクチル、ＴＢＰはリン酸トリブチルを表している。）
【００３０】
これらの表から明らかなとおり、比較的分子量の小さい汚染物質、すなわち低沸点の汚染物質は、吸着剤フィルタが飽和に近づくと吸着されずに通過するか、あるいは吸着、脱離を繰り返し、それにより吸着剤フィルタの吸着能力が失われやすい。これに対し、比較的分子量の大きい有機物、すなわち高沸点の汚染物質は、比較的長期間吸着を継続することができ、飽和後も脱離することが少ない。
【００３１】
例えばクリーンルーム環境を保持するための環境制御装置として用いられる流体浄化装置が取り扱う被処理流体（汚染物質を含む空気）に含まれる汚染物質は、その種類と量が経時的に変動する。被処理流体が、飽和近くなると吸着剤フィルタに捕捉されにくい比較的低分子量の汚染物質と、飽和近くなっても吸着剤フィルタに捕捉される比較的高分子量の汚染物質の両方を含む場合、被処理流体を本発明に従って光触媒ユニット、吸着剤フィルタユニットの順に流すと、被処理流体中の低分子量汚染物質は光触媒により分解除去され、そのため吸着剤フィルタユニットは高分子量汚染物質を含む被処理流体を処理することができる。これにより、光触媒ユニットがなければ吸着剤フィルタユニットにやって来る、吸着剤フィルタでの吸着除去にとって必ずしも適していない低分子量汚染物質が吸着剤フィルタユニットに至ることがなくなるので、吸着剤の吸着部位の実質的に全てを、そこでの吸着除去に適した高分子量汚染物質用に当てることが可能になる。これはまた、吸着剤フィルタの有効寿命を延ばすことにも通じる。
【００３２】
被処理流体が専ら低分子量の汚染物質を含む場合には、汚染物質は光触媒ユニットで分解除去され、吸着剤フィルタユニットは実質的に無負荷の運転となる。このような場合、被処理流体は光触媒ユニットでの処理後に、吸着剤フィルタユニットをバイパスさせることが可能である。
【００３３】
被処理流体が専ら高分子量汚染物質を含む場合には、汚染物質は実質的に処理されることなく光触媒ユニットを通過して吸着フィルタユニットに至り、そこで吸着除去される。このような場合には、被処理流体は光触媒ユニットをバイパスさせることが可能である。このバイパスは、光触媒ユニットがそこで分解除去できない汚染物質で汚染される可能性を排除する点で、有利である。
【００３４】
吸着フィルタユニットの下流には、除塵フィルタユニットを配置することができる。このユニットは、環境制御装置に導入される被処理流体中に最初から含まれていた微粒子状の汚染物質はもちろん、環境制御装置での処理中に生じる微粒子状の異物（例えば、吸着剤フィルタから処理中に微粒子状のゴミが発生することがある）も捕捉することにより、あらゆる種類の汚染物質を含まない清浄な流体の供給を可能にする。除塵フィルタとしては、クリーンルーム用の空気の浄化で広く使用されているＨＥＰＡフィルタ、あるいはＵＬＰＡフィルタ等を用いることができる。
【００３５】
本発明の流体浄化装置は、被処理流体の移送を可能にする流体移送手段を含むことができる。被処理流体が気体の場合、この手段として、ファンを使用することができる。好ましくは、このファンはユニット化して、光触媒ユニット、吸着剤フィルタユニット、そして除塵フィルタを含む場合除塵フィルタユニットと一体にされる。装置の設置条件などから、ファンはその他のユニットと分離して設置しても差し支えない。被処理流体が液の場合は、流体移送手段としてはポンプが一般に使用される。ポンプもユニット化し、そして他のユニットと一体にすることができ、あるいはそれらと分離して設置することができる。
【００３６】
本発明の流体浄化装置においてユニット化（あるいはモジュール化）した構成機器（光触媒、吸着剤フィルタ、除塵フィルタ、流体移送手段）を用いることには、その製造、組み立てや、保守・点検が容易になるという利点がある。例えば、吸着剤フィルタユニットや除塵フィルタユニットを、フィルタエレメントを引き出し式に着脱可能なように作製することにより、フィルタエレメントの交換を容易にすることができる。
【００３７】
本発明の流体浄化装置は、装置に導入する被処理流体及び装置で浄化された流体の一方又は両方の汚染物質を分析する分析器（測定モニタ）を含むこともできる。流体浄化装置への入口側に設けた分析器による分析データを使用して、先に述べた被処理流体の光触媒ユニット又は吸着剤フィルタユニットへの選択的導入のための切り換えを行うことができる。更に、流体浄化装置の出口側に設けた分析器を使用すれば、処理済みの流体中になおも汚染物質が検出された場合に流体を上流側へ戻して再処理することも可能になる。分析器としては、流体浄化装置で処理する流体に含まれることが想定される汚染物質の検出に有効な既知の分析機器を使用することができる。
【００３８】
一例として、ガスクロマトグラフィーを利用した分析を説明する。アセトン、ＭＥＫなどの低沸点の汚染物質と、ＤＢＰ、ＤＯＰなどの高沸点の汚染物質を含む気体の被処理流体を、流体浄化装置の上流側、すなわち被処理流体の入口側の試料を使ってガスクロマトグラフで分析すれば、図１（ａ）に示したような、低沸点成分のピークと高沸点成分のピークの両方を含むガスクロマトグラムが得られ、このとき被処理流体は光触媒ユニットと吸着剤フィルタユニットの両方を通して浄化される。
【００３９】
図１（ｂ）に示したように、流体浄化装置の上流側の試料中に低沸点成分が検出された場合は、被処理流体を光触媒ユニットで処理するようにし、そして光触媒ユニットから出てきた流体は、場合により吸着剤フィルタユニットを通さずにバイパスさせてもよい。一方、図１（ｃ）に示したように、流体浄化装置の上流側の試料中に高沸点成分が検出された場合には、被処理流体を光触媒ユニットをバイパスさせて直接吸着剤フィルタユニットに導入することが可能である。図１（ｄ）は、流体浄化装置の出口側で得られるガスクロマトグラムを示しており、バックグラウンドの応答のみが記録され、汚染物質に対応するピークは見られない。このガスクロマトグラムに、浄化装置からの流体に汚染物質の一部が含まれることを示すピークが観測された場合には、その流体を浄化装置の上流側へ戻すこともできる。
【００４０】
被処理流体あるいは処理済み流体の行き先の変更は、手動で行ってもよく、自動で行ってもよい。自動の場合には、分析器からの信号を処理して変更を自動的に行う信号を発生する制御ユニットを使用することができる。
【００４１】
次に、本発明の流体浄化装置を図面を参照して更に説明するが、本発明はそれらに限定されるものではない。
【００４２】
図２は、本発明の流体浄化装置で使用する光触媒ユニット２と吸着剤フィルタユニット３の組み合わせを示す概略図である。被処理流体としては、例えば、クリーンルーム内の空気に代表される気体を用いることができ、あるいは半導体デバイス生産設備で使用した純水を用いてもよい。被処理流体は、光触媒ユニット２、吸着剤フィルタ３の順番でこの組み合わせを通過する。
【００４３】
光触媒ユニット２には、１５０〜４５０ｎｍの波長帯の紫外線ランプ、又は放電に伴う発光体４と、ガラス材料等の支持体表面上に担持したＴｉＯ_２などの光触媒５が含まれており、このユニットは、例えば特開２００１−６２２５３号明細書に示されたような構造を持つものとして製作することができる。
【００４４】
吸着剤フィルタユニット３は、例えば活性炭、活性炭に添着した中和反応体、あるいはイオン交換繊維等のイオン交換基のような、被処理流体中の汚染物質の吸着除去に適した吸着フィルタを使って製作される。
【００４５】
この組み合わせを使って、無機系もしくは有機系ガス、オゾンガス等の汚染物質を除去することができる。
【００４６】
吸着剤フィルタは、通常は活性炭をベースにしており、吸着量の増大に伴い、例えばアセトン、メタノール、エタノールのような比較的分子量の小さい有機物、すなわち低沸点の有機物から捕捉能力を失っていく傾向にある。例えば中和反応体を添着したような吸着剤フィルタは、吸着量の増大に伴い、吸着剤フィルタが飽和される前に、アセトン、メタノール、エタノールのような分子量の小さい有機物を吸着することができなくなり、これらの物質は吸着剤フィルタユニットを通過してしまうようになる。それらよりやや分子量の大きい、酢酸、蟻酸、イソプロピルアルコール（ＩＰＡ）のような有機物は、吸着した後に脱離する可能性がある。そのため、これらの比較的分子量の小さい有機物は吸着剤フィルタで完全に除去するのにそれほど適しているとは言えない。
【００４７】
一方で光触媒ユニット２は、光触媒作用によって汚染物質を分解するものであり、例えばアセトン、メタノール、エタノールのような分子量の小さい有機物、すなわち低沸点の有機物の分解に優れているが、例えばキシレン、エチルベンゼン、のような比較的分子量の大きい有機物、すなわち高沸点の有機物の分解には、分解効率の面で問題がある。
【００４８】
そこで、被処理流体中の例えばアセトン、メタノール、エタノールのような分子量の小さい有機物、及びこれらよりもやや分子量の大きい酢酸、蟻酸、イソプロピルアルコールのような有機物を、まず光触媒ユニット２で分解、除去し、次に吸着剤フィルタユニット３で、光触媒ユニット２で分解、除去できなかった例えばキシレン、エチルベンゼン、シクロヘキサノンのような比較的分子量の大きい有機物を吸着、除去することにより、様々な汚染物質を含む被処理流体を効率よく処理して浄化することができる。また、吸着剤フィルタユニット３を比較的分子量の大きい汚染物質の吸着除去に専念させることができることから、吸着剤フィルタの吸着能力を長く維持することができる。
【００４９】
光触媒ユニット２と吸着剤フィルタユニット３を効果的に働かせる運転条件は、それらで用いる光触媒と吸着剤フィルタのタイプに依存して決定することができる。
【００５０】
図３に、図２に示した光触媒ユニット２と吸着剤フィルタユニット３の組み合わせを取り入れた本発明の流体浄化装置の一態様を示す。
この態様の装置１は、光触媒ユニット２、吸着剤フィルタユニット３、流体移送手段のユニット８、及び除塵フィルタユニット９をこの順に配列し一体化して構成されており、被処理流体が光触媒ユニット２側から装置１に入り、浄化された流体が除塵フィルタユニット９から出てゆく。このような装置１は、例えば、クリーンルームの壁面又は天井面等、あるいは半導体デバイスなどの生産設備の壁面又は天井面等に設けられ、被処理流体としてのクリーンルーム内の空気を清浄にするのに使用することができる。設置場所の制約により各ユニットを一体化するのが困難な場合などには、それらを隣接せずに離して設置することも可能である。
【００５１】
図３に示した装置１において、ユニット８の流体移送手段としては、被処理流体が気体の場合はファンを、被処理流体が液体の場合はポンプを使用することができる。流体移送手段がファンの場合のユニット８は、図に示した吸着剤フィルタ３と除塵フィルタ９の間に限らず、例えば光触媒ユニット２の上流側に配置してもよく、ユニット８以外のユニット２、３、９の組み合わせと切り離した位置に配置することも可能である。この場合も、流体移送手段のユニット８は、例えば、光触媒ユニット２の上流側に接続するように、あるいは吸い込み側が吸着剤フィルタユニット３の出口側に接続し、そして吐出側が除塵フィルタの入口側に接続するようにすることが可能である。流体移送手段がポンプの場合のユニット８も、任意の位置に配置することができるが、好ましくは光触媒ユニット２の上流側に配置される。被処理流体が気体の場合も液体の場合も、流体移送手段が潜在的汚染源となるので、ユニット８は除塵フィルタユニット９の上流側に設置するのが好ましい。
【００５２】
図４（ａ）〜４（ｃ）に、本発明の流体浄化装置１を環境制御装置として使用する場合の、浄化装置１と制御しようとする環境との位置関係の代表的なものを例示する。図４（ａ）は、浄化装置１を閉鎖系製造装置又は作業ブース１１の天井部に設置した例であり、浄化装置１で浄化した空気を送り込むことにより製造装置又は作業ブース１１内の作業環境を清浄な状態に保つことができる。図４（ｂ）は、浄化装置１を閉鎖系製造装置又は作業ブース１１に隣接して設置した例であり、やはり製造装置又は作業ブース１１内の作業環境を清浄な状態に保つのに使用することができる。この例は、製造装置又は作業ブース１１の天井部に浄化装置１を設置するスペースがない場合に採用することができ、場合によっては浄化装置１を製造装置又は作業ブース１１の壁に直結して設置することも可能である。図４（ａ）と４（ｂ）の例において、製造装置又は作業ブース１１をクリーンルームに替えれば、クリーンルームの作業環境の制御が可能になる。図４（ｃ）は、クリーンルーム内の製造装置又は作業ブース１１からの排気系に浄化装置１を取り入れた例であり、製造装置又は作業ブース１１からの排気中に含まれる汚染物質を除去することでクリーンルームの二次汚染を防止するのに使用することができる。この場合には、クリーンルーム内の作業環境を清浄に制御することになり、そしてその結果として、製造装置又は作業ブース１１自体への清浄空気の供給のために図４（ａ）又は４（ｂ）に示したように設置される別の浄化装置（図示せず）の効率の向上、あるいは特に吸着剤フィルタユニットの長寿命化に寄与することができる。
【００５３】
本発明の浄化装置を、ウエハなどの搬送のために局所クリーン保管部が必要な搬送台車に設置し、そしてこの台車を、これまでボックス搬送手段が一般的であったウエハ等の搬送手段の代わりに使用することも可能である。
【００５４】
図５は、先の例で説明した光触媒ユニット２、吸着剤フィルタユニット３、ファンから構成される流体移送用のユニット８、除塵フィルタ９に加えて、被処理ガスの汚染物質濃度測定モニタ１５、被処理ガスの流動経路を切り換えるためのバルブ１１、１２、１３、１４、そして汚染物質濃度に応じてバルブを切り換えるための制御部１６で構成されている、クリーンルームの環境制御に使用することが可能な本発明の流体浄化装置１０を示している。この場合の非処理ガスは、汚染物質を含有している可能性のある空気である。
【００５５】
例えば、汚染物質濃度測定モニタ１５、１７として、クリーンルーム内での有機物による汚染の原因と考えられている、やや分子量の小さい有機物のＩＰＡと、比較的分子量の大きい有機物のシクロヘキサノンの量を測定するモニタを使用する。
【００５６】
クリーンルームに導入される被処理ガスの空気中にＩＰＡの含まれることが汚染物質濃度測定モニタ１５で検出される場合は、制御部１６からの信号によりバルブ１１が開き、バルブ１２が閉じて、光触媒ユニット２でＩＰＡを分解、除去する。光触媒ユニット２でＩＰＡを除去したガスは、やはり制御部１６からの信号によりバルブ１３を閉じ、バルブ１４を開いて吸着剤フィルタユニット３をバイパスすることができる。ＩＰＡを除去したガスは、次いで流体移送用のユニット８により除塵フィルタ９を通してクリーンルーム内へ供給される。
【００５７】
被処理ガスの空気中にＩＰＡが検出されず、シクロヘキサノンが検出される場合は、制御部１６からの信号によりバルブ１１を閉じ、バルブ１２を開いてガスを光触媒ユニット２をバイパスさせて吸着剤フィルタユニット３へ直接送り、吸着剤フィルタによりシクロヘキサノンを吸着、除去する。
【００５８】
被処理ガスの吸気中にＩＰＡとシクロヘキサノンの両方が検出される場合は、バルブ１１、１３が開き、バルブ１２、１４が閉じて、ＩＰＡを光触媒ユニット２で分解、除去した後、シクロヘキサノンを吸着剤フィルタユニット３で吸着、除去する。
【００５９】
光触媒ユニット２は、光触媒での分解、除去に適した分子量の小さい有機物が被処理ガス中に含まれている場合に、バルブ１１を開いて被処理ガスを受け取り、そうでない場合はバルブ１１を閉じて被処理ガスをバイパスさせることができるため、励起光源の紫外線ランプ又は放電に伴う発光体の長寿命化に寄与するとともに、その定期的な洗浄又は交換回数を減らすことができる。同様に、支持体に担持した光触媒の定期的な洗浄又は交換回数を減らすこともできる。
【００６０】
吸着剤フィルタユニット３は、常に分子量の小さい有機物のないガスを受け取り、またこのユニットで処理すべき分子量の大きい有機物がないガスをバイパスさせることもできるため、やはり吸着剤フィルタ３の長寿命化及び吸着剤フィルタの交換回数の減少を実現することができる。
【００６１】
汚染物質濃度測定モニタ１５の測定結果によるバルブ１１、１２、１３、１４の開閉制御は、制御部１６を使用せずに、手動で行ってもよい。
【００６２】
更に、浄化装置１の出口側に汚染物質濃度測定モニタ１７を追加して設置することも可能である。出口側の測定モニタ１７は、光触媒ユニット２又は吸着剤フィルタユニット３の寿命を確認する手段として有効であり、有機物が多く検出される場合は、検出される有機物の種類に応じて、光触媒ユニット２又は吸着剤フィルタユニット３が劣化したと判断することができる。このモニタ１７の測定結果を、バルブ１１、１２、１３、１４の制御によるガス流動経路の変更に反映することも可能である。あるいは、浄化装置１の入口側の汚染物質濃度測定モニタ１５を省き、出口側の測定モニタ１７のみを設けることも可能である。
【００６３】
オゾンガスの測定が可能な汚染物質濃度測定モニタ１７を用いることにより、浄化装置１０をオゾンを含むガスの浄化に利用することもできる。オゾンは半導体ウエハ表面を酸化してしまうため、効率よく除去する必要がある。オゾンは、吸着剤フィルタ３により酸素に還元して除去される。しかし、光触媒はどちらかと言えば酸化剤として機能するため、オゾンの発生に加担することはあっても、その除去に寄与することはできない。そこで、汚染物質濃度測定モニタ１５、１７でオゾンガスが検出された場合は、バルブ１１、１３、１４を閉じて、バルブ１２を開ける。オゾンを含むガスは光触媒ユニット２をバイパスして吸着剤フィルタユニット３に流れるため、効率よくオゾンを除去することができる。
【００６４】
汚染物質濃度測定モニタ１５、１７として、有機物の総量を測定するモニタを使用し、その測定結果に基づいてガスの流動経路を変更するようにしてもよい。これは、例えば、通常の被処理ガス中の汚染物質の種類と量が決まっていて、それ以外の汚染物質として光触媒での処理が有効な物質が被処理ガス中に時折含まれることがあるような場合に、特に有効である。
【００６５】
汚染物質濃度測定モニタ１５、１７は、被処理ガス中の汚染物質の種類と量の変動が予測されるときのような、必要時に設置するようにしてもよい。また、汚染物質濃度測定モニタ１５、１７をガスの流動経路中に設けずに他の場所に設置し、ガス流動経路から採取したサンプルを他の場所に設置した測定モニタで測定してもよい。
【００６６】
更に、バルブ１１、１２、１３、１４の代わりに、ダンパーやスリット式の開閉シャッターを用いることも可能である。また、バルブ１３、１４はなくてもよく、バルブ１１、１２の切り換えのみでも同様な効果は期待できる。
【００６７】
流体浄化装置１０を多段に設置することで、更に効率的な浄化を行うことも可能である。また、流体浄化装置１０自体を、例えばステンレスの箱に入れると、より効率的な浄化が可能になる。
【００６８】
図６は、図５を参照して説明した流体浄化装置１０に、除塵フィルタユニット９の出口側から流体浄化装置の上流側への循環経路と、この循環経路への切り換え用のバルブ１８、１９とを追加した態様の流体浄化装置１０’を示している。この浄化装置１０’を使用して種々の汚染物質を含むガスを浄化する例を、以下で説明する。
【００６９】
最初の例は、半導体デバイスの製造においてシリコンウエハの酸化の原因になる酢酸、蟻酸などの汚染物質を含む空気を被処理ガスとして使用し、汚染物質の総量（ＴＯＣ）を測定する水晶振動子型膜厚モニタを汚染物質濃度測定モニタ１５、１７として使用する。各バルブ１１、１２、１３、１４、１８、１９の切り換えは、ＴＯＣの測定結果に基づき、制御部１６からの信号により自動で行う。
【００７０】
水晶振動子型膜厚モニタ１５で被処理ガスの汚染物濃度を測定する。汚染物濃度が低いときは、バルブ１１、１４を開き、バルブ１２、１３を閉じて、光触媒ユニット２でガスを浄化する。通常、浄化装置１０’の出口側のバルブ１８は開き、循環経路のバルブ１９は閉じておく。汚染物濃度が中レベルの時は、バルブ１１を閉じ、バルブ１２を開いて、吸着剤フィルタユニット３でガスを浄化する。汚染物濃度が高いときは、バルブ１１、１３を開き、バルブ１２、１４を閉じて、光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化する。
【００７１】
水晶振動子型膜厚モニタ１７で浄化ガスの汚染物濃度を監視する。光触媒ユニット２のみでガスを浄化していてモニタ１７で汚染物質が検出されたときは、バルブ１３を開き、バルブ１４を閉じて、光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化するように浄化装置１０’の運転を切り換える。吸着剤フィルタユニット３のみでガスを浄化していて汚染物が検出されたときは、バルブ１１、１３を開き、バルブ１２、１４を閉じて、やはり光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化するように運転を切り換える。光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化していて汚染物質が検出されたときは、バルブ１８を閉じ、バルブ１９を開いてガスを循環させ、再度浄化を行う。
【００７２】
２番目の例は、被処理ガス中の汚染物質としてのＮＯ_ｘ、ＳＯ_ｘ、オゾンを除去する。測定モニタ１５、１７に、除去しようとするＮＯ_ｘ、ＳＯ_ｘ又はオゾンを測定するためのモニタを使用する。除去対象の汚染物質が２以上の場合は、各汚染物質用の測定モニタを用意する。
【００７３】
測定モニタ１５で被処理ガスの汚染物濃度を測定する。汚染物濃度が高いときは、バルブ１１を閉じ、バルブ１２を開いて、吸着剤フィルタユニット３でガスを浄化する。汚染物濃度が低いときは、バルブ１１、１４を開き、バルブ１２、１３を閉じて、光触媒ユニット２でガスを浄化する。通常、浄化装置１０’の出口側のバルブ１８は開き、バルブ１９は閉じておく。
【００７４】
測定モニタ１７で浄化ガスの汚染物濃度を監視する。光触媒ユニット２のみでガスを浄化していて測定モニタ１７で汚染物が検出されたときは、バルブ１３を開き、バルブ１４を閉じて、光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化するよう、浄化装置１０’の運転を切り換える。吸着剤フィルタユニット３のみでガスを浄化していて汚染物が検出されたときは、バルブ１１、１３を開き、バルブ１２、１４を閉じて、やはり光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化するように運転を切り換える。光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化していて汚染物が検出されたときは、バルブ１８を閉じ、バルブ１９を開いてガスを循環させ、再度浄化処理する。
【００７５】
３番目の例は、アンモニアの除去によりガスを浄化する。測定モニタ１５、１７に、アンモニア測定モニタを使用する。
【００７６】
測定モニタ１５で被処理ガスのアンモニア濃度を測定する。アンモニア濃度が高いときは、バルブ１１、１３を開き、バルブ１２、１４を閉じて、光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化する。アンモニア濃度が低いときは、バルブ１１、１４を開き、バルブ１２、１３を閉じて光触媒ユニット２でガスを浄化するか、あるいはバルブ１１、１４を閉じ、バルブ１２を開いて吸着剤フィルタユニット３で浄化する。通常、浄化装置１０’の出口側のバルブ１８は開き、バルブ１９は閉じておく。
【００７７】
測定モニタ１７で浄化ガスのアンモニア濃度を監視する。アンモニアが検出されたときは、バルブ１８を閉じ、バルブ１９を開いてガスを循環させ、ガスを再度浄化処理する。光触媒ユニット２か吸着剤フィルタユニット３のどちらかのみで浄化を行っていた場合は、ガスを循環させてもよく、あるいは運転を停止していた方のユニットも稼働するようにバルブを切り換えてもよく、あるいはガスを循環させ且つ停止していた方のユニットを稼働するようにしてもよい。
【００７８】
図７は、図６を参照して説明した流体浄化装置１０’の各バルブ１１、１２、１３、１４、１８、１９の切り換えを手動で行う例を示している。この図の流体浄化装置１０”では、測定モニタ１５、１７に、ガスの吸着管であるＴＥＮＡＸ管を使用する。吸着した有機物ガスをＴＥＮＡＸ管から脱着してガスクロマトグラフにより定性、定量分析し、その結果に基づき、各バルブを手動操作する。
【００７９】
分析の結果、分子量の小さい有機物ガスが多いときは、バルブ１１、１４を開き、バルブ１２、１３を閉じて、光触媒ユニット２のみでガスを浄化する。分子量の大きい有機物ガスが多いときは、バルブ１１を閉じ、バルブ１２を開いて、吸着剤フィルタユニット３のみでガスを浄化する。通常、浄化装置１０”の出口側のバルブ１８は開き、循環経路のバルブ１９は閉じておく。
【００８０】
測定モニタ１７で浄化ガスの有機物ガス濃度を監視する。有機物ガスが検出されたときは、バルブ１１、１３を開き、バルブ１２、１４を閉じて、光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化する。光触媒ユニット２と吸着剤フィルタユニット３の両方でガスを浄化していて、測定モニタ１７で分子量の小さい有機物ガスが検出されるときは、光触媒が寿命に達し、分子量の大きい有機物ガスが検出されるときは、吸着剤フィルタが寿命に達していると見なされ、寿命に達したものを交換する。この交換時には、バルブ１８を閉じ、バルブ１９を開き、正常である（交換しない）方の光触媒ユニット２又は吸着剤フィルタ３を通してガスを循環させるよう、バルブ１１〜１４を切り換える。
【００８１】
被処理ガスの流動経路を切り換えて運転する図５〜７の流体浄化装置１０、１０’、１０”において、除塵フィルタユニット９は吸着フィルタユニット３の下流側に配置されているが、これは必ずしも吸着剤フィルタユニット３の下流側に位置する必要はない。例えば、被処理ガスの流動経路切り換え用にバルブ１１、１２で分岐する前の被処理ガス流路に同様の機能の除塵フィルタが設けられている場合には、この除塵フィルタを図５〜７における除塵フィルタ９の代わりに利用してもよい。同様に、図５〜７の流体浄化装置１０、１０’、１０”では流体移送用のユニット８は吸着フィルタユニット３と除塵フィルタ９との間に配置されているが、このユニット８の位置はこれに限定されず、例えば、被処理ガスの流動経路切り換え用にバルブ１１、１２で分岐する前の被処理ガス流路に配置することも可能である。
【００８２】
既に述べたように、本発明の流体浄化装置では、分子量の小さい、低沸点の有機物の分解除去に優れた光触媒ユニットを第１段に配置し、分子量の大きい、高沸点の有機物の吸着除去に優れた吸着剤フィルタを第２段に配置している。図５〜７を参照して説明したように、本発明の流体浄化装置では被処理流体中の汚染物質の種類に応じてどちらかのユニット又は両方のユニットを使って流体の浄化を行うことができるが、被処理流体中の汚染物質の種類にかかわらず、最初は、低分子量、低沸点の有機物の吸着除去もできる吸着剤フィルタユニットにもっぱら被処理ガスを導入するようにしてもよい。浄化が進行し、吸着剤フィルタが飽和に近づくと、低分子量の有機物は吸着剤フィルタを通過し始め、浄化装置の出口側に設けられた測定モニタで検出され始める。この時点で、被処理流体の流動経路を変更して光触媒ユニットから導入するようにし、そこで低分子量の有機物を分解除去したガスを吸着剤フィルタユニットに供給することができる。こうして吸着剤フィルタユニットには分子量の大きい有機物が供給されるため、飽和に近づいた吸着剤フィルタでのガスの浄化を更に継続することが可能になる。
【００８３】
あるいはまた、被処理流体の流動経路の変更を行わず、被処理流体を常に光触媒ユニット、吸着剤フィルタユニットの順に浄化処理することも可能である。この場合にも、光触媒ユニットで低分子量の有機物が分解除去されたガスが吸着剤フィルタユニットに供給されるため、吸着剤フィルタの最大限の能力を有効利用することができる。
【００８４】
本発明の流体浄化装置には、図８に示したように、チラー等を利用した恒温・恒湿ユニット２２を付加することも可能である。この図に示した流体浄化装置２１は、恒温・恒湿ユニット２２を光触媒ユニット２の手前に含むことを除き、図５〜７を参照して説明した流体浄化装置１０、１０’、１０”と同様に構成することができ、図８に示した参照符号で図５〜７で用いたのと同じものはそれらに示したのと同じユニットを示している。図８の装置は、もちろんながら、図５〜７に示されていてこの図に示されていない機器（バルブ、測定モニタ、制御部）を含むこともできる。ユニットを分離して配置可能なこと、流体移送手段８の位置の変更が可能なことも、先に説明した浄化装置１０、１０’、１０”の場合と同様である。
【００８５】
恒温・恒湿ユニット２２を用いることにより、それに続く光触媒ユニット２、吸着剤フィルタユニット３でのガスの浄化に最適な条件のガスを供給することができる。
【００８６】
また、図８に示した恒温・恒湿ユニット２２を備えた流体浄化装置も、ウエハなどの搬送のために局所クリーン保管部が必要な搬送台車に設置し、この台車をこれまでボックス搬送手段が一般的であったウエハ等の搬送手段の代わりに使用することができる。
【００８７】
図９に、本発明の流体浄化装置３１をクリーンブース３０内の環境制御のために用いた例を示す。この流体浄化装置３１も、図５〜７を参照して説明した流体浄化装置１０、１０’、１０”と同様に構成することができ、図９に示した参照符号で図５〜７で用いたのと同じものはそれらに示したのと同じ構成要素を示している。図８の装置も、図５〜７に示されていてこの図に示されていない構成要素（バルブ、制御部）を含むことができる。ユニットを分離して配置可能なこと、流体移送手段８の位置の変更が可能なことも、先の浄化装置１０、１０’、１０”の場合と同様である。
【００８８】
外気を導入して浄化装置３１で処理した浄化空気をクリーンブース３０へ供給する。クリーンブース３０内の空気の浄化効率を高めるため、浄化装置３１で処理するガス量のうちの、例えば９０％を、循環流路３３によりクリーンブース３０から取り出し、浄化装置３１へ導入する外気と一緒にしてもよい。この循環により、浄化装置３１の浄化効率を上げることができる（浄化装置３１からクリーンブース３０へ供給される清浄空気と同じ空気が循環するとし、その循環量を浄化装置３１の処理ガス量の９０％とすれば、浄化装置３１の浄化効率は１０倍向上することになる）。
【００８９】
更に、浄化装置３１の手前に、図８を参照して説明したような恒温・恒湿ユニットを設けることも可能である。
【００９０】
図１０に、本発明の流体浄化装置４１をＳＭＩＦ−ボックス４２の開口部４０の環境制御のために用いた例を示す。この流体浄化装置４１も、図５〜７を参照して説明した流体浄化装置１０、１０’、１０”と同様に構成することができ、図１０に示した参照符号で図５〜７で用いたのと同じものはそれらに示したのと同じ構成要素を示している。図１０の装置も、図５〜７に示されていてこの図に示されていない構成要素（バルブ、制御部）を含むことができる。ユニットを分離して配置可能なこと、流体移送手段８の位置の変更が可能なことも、先の浄化装置１０、１０’、１０”の場合と同様である。
【００９１】
ＳＭＩＦ−ボックス４２の開口部４０は、デバイス製造過程のウエハ４８などをＳＭＩＦ−ボックス４２より自動で出し入れする部分であり、その環境浄化は、ＳＭＩＦ−ボックス４２の開閉時にのみ必要とされる。この必要時に、浄化装置４１からの浄化空気をＳＭＩＦ−ボックス開口部４０へ供給し、供給不要時には、循環流路４３により全量を浄化装置４１へ戻し、循環させる。この切り換えは、図示しないバルブで行うことができる。
【００９２】
本発明は、以上説明したとおりであるが、その特徴を種々の態様とともに付記すれば、次のとおりである。
（付記１）被処理流体から汚染物質を除去してそれを浄化する装置であって、被処理流体中の汚染物質を分解可能な光触媒及びこの光触媒を励起するための励起光源を有する光触媒ユニットと、被処理流体中の汚染物質を吸着し得る吸着剤フィルタユニットとを含み、被処理流体の流動方向に対し光触媒ユニットを吸着剤フィルタユニットの上流側に配置し、且つ更に、吸着剤フィルタユニットの下流側に配置した除塵フィルタユニットを含むことを特徴とする流体浄化装置。
（付記２）前記被処理流体を前記光触媒ユニット又は前記吸着剤ユニットへ選択的に導入する切り換え手段を更に含む、付記１記載の流体浄化装置。
（付記３）被処理流体から汚染物質を除去してそれを浄化する装置であって、被処理流体中の汚染物質を分解可能な光触媒及びこの光触媒を励起するための励起光源を有する光触媒ユニットと、被処理流体中の汚染物質を吸着し得る吸着剤フィルタユニットとを含み、被処理流体の流動方向に対し光触媒ユニットを吸着剤フィルタユニットの上流側に配置し、且つ更に、被処理流体を光触媒ユニット又は吸着剤ユニットへ選択的に導入する切り換え手段を含むことを特徴とする流体浄化装置。
（付記４）前記被処理流体が前記光触媒ユニットでの光触媒作用による除去に適した汚染物質を含むとき、当該被処理流体を前記光触媒ユニットに導入し、前記被処理流体が前記吸着剤ユニットでの吸着による除去に適した汚染物質を含むとき、当該被処理流体を吸着剤フィルタユニットに導入する、付記２又は３記載の流体浄化装置。
（付記５）前記被処理流体が前記光触媒ユニットでの光触媒作用による除去に適した汚染物質を含むとき、前記光触媒ユニットで処理したガスに前記吸着剤ユニットをバイパスさせる、付記４記載の流体浄化装置。
（付記６）前記被処理流体中の汚染物質の濃度が低いときはそれを選択的に前記光触媒ユニットで浄化し、前記被処理流体中の汚染物質の濃度が中レベルのときはそれを選択的に前記吸着剤フィルタユニットで浄化し、前記被処理流体中の汚染物質の濃度が高いときは前記光触媒ユニットと前記吸着剤フィルタユニットの両方でそれを浄化する、付記２又は３記載の流体浄化装置。
（付記７）浄化した流体中に前記汚染物質が検出された場合において、前記被処理流体を選択的に前記光触媒ユニットで浄化していたときは前記吸着剤フィルタユニットでも当該被処理流体を浄化するよう当該流体浄化装置の運転を切り換え、前記被処理流体を選択的に前記吸着剤フィルタユニットで浄化していたときは前記光触媒ユニットでも当該被処理ガスを浄化するよう当該流体浄化装置の運転を切り換え、前記光触媒ユニットと前記吸着剤フィルタユニットの両方で前記被処理流体を浄化していたときは当該流体を循環させて当該流体浄化装置において再度浄化処理する、付記６記載の流体浄化装置。
（付記８）当該流体浄化装置で除去しようとする汚染物質が１種類であり、前記被処理流体中の当該汚染物質の濃度が高いときは前記光触媒ユニットと前記吸着剤フィルタユニットの両方で当該被処理流体を浄化し、当該汚染物質の濃度が低いときは前記光触媒ユニットと前記吸着剤フィルタユニットのどちらか一方で当該被処理流体を浄化する、付記２又は３記載の流体浄化装置。
（付記９）前記光触媒ユニットと前記吸着剤フィルタユニットの両方で浄化を行っていた場合において、前記浄化を受けた被処理流体中に前記汚染物質が検出されたとき、当該被処理流体を循環させる、付記８記載の流体浄化装置。
（付記１０）前記光触媒ユニットと前記吸着剤フィルタユニットのどちらか一方で浄化を行っていた場合において、当該浄化を受けた被処理流体中に前記汚染物質が検出されたとき、当該被処理流体を循環させるか、浄化を行っていなかった方のユニットも浄化に使用するか、あるいは当該被処理流体を循環させて且つ浄化を行っていなかった方のユニットも浄化に使用する、付記８記載の流体浄化装置。
（付記１１）前記切り換え手段が自動式の手段である、付記２又は３記載の流体浄化装置。
（付記１２）前記切り換え手段が手動式の手段である、付記２又は３記載の流体浄化装置。
（付記１３）前記被処理流体を移送するための流体移送手段を更に含む、付記２記載の流体浄化手段。
（付記１４）前記流体移送手段が前記吸着剤フィルタユニットと前記除塵フィルタユニットとの間に位置する、付記１３記載の流体浄化装置。
（付記１５）前記被処理流体を移送するための流体移送手段を更に含む、付記３記載の流体浄化手段。
（付記１６）前記吸着剤フィルタユニットの下流側に配置した除塵フィルタユニットを更に含み、且つ、前記流体移送手段が前記吸着剤フィルタユニットと当該除塵フィルタユニットとの間に位置している、付記１５記載の流体浄化装置。
【００９３】
【発明の効果】
以上説明したように、本発明によれば、光触媒の効率的な使用により、吸着剤フィルタを長寿命化し、且つ汚染物除去効率を高めた流体除去装置の利用が可能になり、クリーンルームをはじめとする環境制御の不可欠な空間の環境制御を容易にすることができる。
【図面の簡単な説明】
【図１】種々のガスについて得られるガスクロマトグラムを模式的に説明する図である。
【図２】本発明の流体浄化装置で使用する光触媒ユニットと吸着剤フィルタユニットの組み合わせを模式的に示す図である。
【図３】本発明の流体浄化装置の一態様を説明する図である。
【図４】本発明の流体浄化装置の使用形態の例を示す図である。
【図５】本発明の流体浄化装置のもう一つの態様を説明する図である。
【図６】本発明の流体浄化装置の別の態様を説明する図である。
【図７】本発明の流体浄化装置の更に別の態様を説明する図である。
【図８】本発明の流体浄化装置のなおもう一つの態様を説明する図である。
【図９】本発明の流体浄化装置をクリーンブース内の環境制御のために用いた例を示す図である。
【図１０】本発明の流体浄化装置をＳＭＩＦ−ボックスの開口部の環境制御のために用いた例を示す図である。
【符号の説明】
１、１０、１０’、１０”、２１、３１、４１…流体浄化装置
２…光触媒ユニット
３…吸着剤フィルタユニット
８…流体移送手段のユニット
９…除塵フィルタユニット
１１、１２、１３、１４、１８、１９…バルブ
１５、１７…汚染物質濃度測定モニタ
１６…制御部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention uses a photocatalyst and an adsorbent filter to remove contaminants in a gas or a liquid by decomposing and adsorbing them with high efficiency, and to supply a clean fluid for a long period of time. The present invention relates to a fluid purification device that can be suitably used as a device.
[0002]
[Prior art]
In recent years, the integration and quality of semiconductor devices have been increasing, and fine contaminants that cannot be removed by high-performance dust filters (generally known as HEPA filters or ULPA filters), for example, in the case of gas, organic contaminants. Contaminants at the molecular level, such as gas, inorganic gas, and ozone gas, have become problems as a cause of device manufacturing defects.
[0003]
It is known to remove contaminants such as organic gas, inorganic gas, and ozone gas with an adsorbent. As the adsorbent, an adsorbent filter (commonly called a chemical filter) composed of activated carbon, activated carbon to which a neutralizing reactant is attached, or an ion exchange group such as ion exchange fiber is provided.
[0004]
In the removal of contaminants by the adsorbent filter, for example, organic gas or ozone gas is removed by physical adsorption or decomposition by granular or fibrous activated carbon or the like. The acidic gas is removed by chemically adsorbing with granular or fibrous activated carbon to which potassium carbonate is impregnated, or by performing ion exchange with an ion exchange group such as ion exchange fiber. The alkaline gas is chemically adsorbed by, for example, granular or fibrous activated carbon to which phosphoric acid is impregnated, or removed by ion exchange with an ion exchange group such as ion exchange fiber. These adsorbent filters are composed of layered elements, and are generally used as a unit including one or a combination of two or more layers.
[0005]
The adsorption efficiency of the adsorbent filter decreases as the amount of contaminant adsorbed approaches saturation, and when the adsorbent filter is completely saturated, it is necessary to replace the adsorbent filter. In an adsorbent filter composed of activated carbon, a neutralizing reactant impregnated on activated carbon, or an ion exchange group such as an ion exchange fiber, an organic substance having a relatively small molecular weight, that is, an organic substance having a low boiling point, is saturated with the adsorbent filter. When approaching, there is a problem that the substance passes without adsorbing or that adsorbing and desorbing are repeated and the adsorbing ability is lost. On the other hand, it is excellent in adsorbing organic substances having a relatively large molecular weight, that is, organic substances having a high boiling point, and can continue adsorption for a relatively long time without desorbing even after saturation.
[0006]
The replacement cycle of the adsorbent filter varies depending on the contaminated environment. However, in a general semiconductor device factory, it is about 0.5 to 2 years, and an adsorbent filter unit having a longer life is demanded.
[0007]
It has also been proposed to apply a photocatalyst to the removal of contaminants at the molecular level (for example, JP-A-2001-62253). When a photocatalyst is used, contaminants are removed by oxidative decomposition by photocatalysis. The photocatalyst is excellent in decomposing organic substances having a relatively small molecular weight, that is, organic substances having a low boiling point. The photocatalyst unit that removes contaminants by photocatalysis includes a photocatalyst (for example, titanium oxide or the like) supported on the surface of a support, and an excitation light source that emits ultraviolet light that excites the photocatalyst.
[0008]
Since the photocatalytic unit has its own life or deterioration such as the lamp of the excitation light source, it needs to be periodically cleaned or replaced. In addition, a support such as a glass material that is exposed to contaminants gradually needs to be cleaned or replaced because dirt gradually adheres thereto.
[0009]
JP-A-11-123316 discloses that a particle filtration layer, a photocatalyst holding layer, an ion-exchange fiber packed layer (or an activated carbon-based fiber packed layer, or a mixed packed layer of ion-exchange fibers and activated carbon-based fibers) are used in this order. An ultra-clean air production device that purifies through process air is described. In this apparatus, it is described that the particle filtration layer is in front (upstream side) of the photocatalyst holding layer and the ion exchange fiber packed layer, and that the air to be treated is selectively introduced into the photocatalyst holding layer or the ion exchange fiber packed layer. It has not been.
[0010]
Japanese Patent Application Laid-Open No. 11-300150 describes an air purifying filter for use in a vehicle, which is excellent in deodorizing function, using a chemical adsorbent, a physical adsorbent, and a photocatalyst. The chemical adsorbent, the physical adsorbent and the photocatalyst are not individually unitized but are substantially integrated. The air to be treated cannot be selectively supplied to the adsorbent and the photocatalyst.
[0011]
Japanese Patent Application Laid-Open No. 11-47256 describes a deodorizing apparatus in which a gas adsorbing filter and a photocatalyst are arranged in this order. If a dust filter is used, it is located further in front of the gas-adsorbing filter. There is no mention of selectively supplying air to the adsorbent and the photocatalyst.
[0012]
JP-A-2001-232154 describes a deodorizer in which two types of activated carbon (adsorbent) and a photocatalyst are supported on a filter as a supporting means. The adsorbent of activated carbon and the photocatalyst are supported on the same filter, and the air to be treated cannot be selectively introduced into each.
[0013]
[Patent Document 1]
JP 2001-62253 A
[Patent Document 2]
JP-A-11-123316
[Patent Document 3]
JP-A-11-300150
[Patent Document 4]
JP-A-11-47256
[Patent Document 5]
JP 2001-232154 A
[0014]
[Problems to be solved by the invention]
As described above, there is a need for a fluid purification device that can stably supply a purified fluid even after the adsorbent filter approaches a saturated state. In particular, there is a need for a technology for maintaining an environment, such as a clean room, which requires a high degree of cleanliness, which is indispensable for the manufacture of electronic devices, at a stable level of cleanliness.
[0015]
An object of the present invention is to provide a fluid purifying apparatus that makes it possible to stably supply a highly clean fluid for a long period of time by making the most of the adsorption capacity of an adsorbent filter used in such a fluid purifying apparatus. It is to be.
[0016]
[Means for Solving the Problems]
In one aspect, the fluid purification device of the present invention is a device that removes contaminants from a treatment target fluid that is a fluid flowing into an enclosed environment such as a clean room, and mainly removes contaminants in the treatment target fluid. A photocatalyst unit having a decomposable photocatalyst and an excitation light source for exciting this photocatalyst, and an adsorbent filter unit capable of adsorbing contaminants in the fluid to be treated, wherein the photocatalyst unit is arranged in the flow direction of the fluid to be treated. It is characterized by including a dust removal filter unit disposed upstream of the adsorbent filter unit and further disposed downstream of the adsorbent filter unit.
[0017]
In another aspect, the fluid purification apparatus of the present invention is an apparatus for removing contaminants from a processing fluid, comprising a photocatalyst capable of decomposing contaminants in the processing fluid and an excitation light source for exciting the photocatalyst. Including a photocatalyst unit having an adsorbent filter unit capable of adsorbing contaminants in the fluid to be treated, the photocatalyst unit is arranged on the upstream side of the adsorbent filter unit with respect to the flow direction of the fluid to be treated, and further, It is characterized by including switching means for selectively introducing the fluid to be treated into the photocatalytic unit or the adsorbent unit.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
In the fluid purification device of the present invention, a combination of a photocatalyst unit and an adsorbent filter unit is used. Both of these enable the removal of fine, molecular-level contaminants that cannot be removed by high-performance dust filters such as HEPA and ULPA filters.
[0019]
The photocatalyst contained in the photocatalytic unit is particularly excellent for decomposing organic substances having a relatively small molecular weight, that is, organic substances having a low boiling point. By first treating the fluid containing contaminants with the photocatalyst unit, it is possible to selectively decompose and remove low-boiling organic matter having a relatively small molecular weight. The high-boiling organic matter having a relatively large molecular weight that is not easily decomposed by the photocatalyst passes through (or bypasses) the photocatalyst unit, reaches the adsorbent filter unit, and is removed by being adsorbed by the adsorbent filter.
[0020]
An important point of the fluid purification apparatus of the present invention is that a fluid to be treated is treated in the order of a photocatalyst unit and an adsorbent filter unit to remove contaminants. By observing this order, contaminants having a high molecular weight selectively flow into the adsorbent filter unit, and the adsorbent filter can maintain its adsorption ability for a long time. If this order is reversed and the fluid to be treated is supplied to the adsorbent filter unit first, the adsorbent filter will adsorb the contaminant regardless of the molecular weight, and the adsorbent filter will be saturated with the contaminant having a small molecular weight. The adsorption capacity of contaminants having a high molecular weight is reduced by that amount.
[0021]
The photocatalyst unit used in the present invention includes a photocatalyst and an excitation light source for exciting the photocatalyst. As an example, the photocatalyst is used by being supported on a transparent support such as a glass material. A typical photocatalyst is titanium oxide (TiO 2). ₂ ), Which are excited by ultraviolet irradiation to oxidatively decompose low molecular weight contaminants such as acetone, methanol, ethanol, and methyl ethyl ketone.
[0022]
As the excitation light source, an ultraviolet lamp that emits light effective for exciting the photocatalyst or a light emitting body by electric discharge can be used. The excitation light source may be provided in the same atmosphere as the photocatalyst, or may be provided separately from the atmosphere in which the photocatalyst is located. In the former case, the excitation light source is exposed to the flow of the fluid to be treated together with the photocatalyst, and is located relatively adjacent to the photocatalyst. In the latter case, the excitation light source is separated from the photocatalyst by a light-transmissive partition wall such as quartz glass, and does not come into direct contact with the fluid to be treated containing the contaminants.
[0023]
The photocatalyst is selected according to the type of contaminant to be treated, and the light source for exciting it is selected according to the selected photocatalyst type. In the case of titanium oxide, which is a typical photocatalyst, a lamp that emits ultraviolet light in a wavelength band of 150 to 450 nm or a light-emitting body by discharge can be suitably used.
[0024]
Although the photocatalyst unit is widely known and need not be described further here, as an example, a thin film of titanium oxide was formed on the inner surface or inner and outer surface of a glass tube disclosed in JP-A-2001-62253. The thing using a photocatalyst can be mentioned.
[0025]
The adsorbent filter unit is constituted by a layered element containing activated carbon, a neutralizing reactant impregnated on activated carbon, an ion exchange group such as ion exchange fiber, or a combination thereof. As the adsorbent filter, for example, a filter supplied under the name of a chemical filter can be used. For example, granular or fibrous activated carbon is suitable for removing organic gas or decomposing ozone gas by physical adsorption, and granular or fibrous activated carbon impregnated with potassium carbonate or the like is suitable for removing acidic gas by chemical adsorption. Are suitable. The acidic gas may be removed by ion exchange with an adsorbent filter using ion exchange groups such as ion exchange fibers. The alkaline gas can be removed by chemical adsorption with granular or fibrous activated carbon to which phosphoric acid is impregnated, or by ion exchange with ion exchange groups such as ion exchange fibers.
[0026]
Although adsorbent filters can remove contaminants at the molecular level that cannot be removed by high-performance dust filters such as HEPA filters or ULPA filters, when the adsorption of contaminants approaches saturation, the size of contaminant molecules increases. This causes a difference in adsorption performance. Tables 1 and 2 show the adsorption performance of various contaminant molecules.
[0027]
[Table 1]

[0028]
[Table 2]

[0029]
Table 1 shows the adsorption performance of the adsorbent filter at the start of adsorption. Each contaminant molecule shown in this table is adsorbed and held by the adsorbent filter. Table 2 shows the adsorptivity when the adsorption progresses and approaches the saturation. The compounds in the leftmost column of the table are not trapped by the sorbent filter and begin to pass. These are compounds having relatively small molecular weights. The compounds in the second and third columns from the left of the table are adsorbed but may desorb later and leak out of the adsorbent filter. The compounds in the rightmost column of the table remain adsorbed and retained on the adsorbent without being desorbed. These are relatively high molecular weight compounds. (In Tables 1 and 2, D2 to D6 represent a basic structural unit -Si (CH ₃ ) ₂ O- is a silicone compound of 2 to 6 each, MEK is methyl ethyl ketone, IPA is isopropyl alcohol, PGMEA is propylene glycol monomethyl ether acetate, PGME is propylene glycol monomethyl ether, NMP is N-methylpyrrolidone, DBP is dibutyl phthalate, DOP Represents dioctyl phthalate, and TBP represents tributyl phosphate. )
[0030]
As is evident from these tables, relatively low molecular weight contaminants, i.e., low boiling contaminants, either pass through without being adsorbed when the adsorbent filter approaches saturation, or repeatedly adsorb and desorb, Adsorption capacity of the adsorbent filter is easily lost. On the other hand, an organic substance having a relatively large molecular weight, that is, a contaminant having a high boiling point, can continue to be adsorbed for a relatively long time, and is hardly desorbed even after saturation.
[0031]
For example, the type and amount of contaminants contained in a fluid to be treated (air containing contaminants) handled by a fluid purification device used as an environment control device for maintaining a clean room environment fluctuate over time. If the fluid to be treated contains both relatively low molecular weight contaminants that are less likely to be trapped by the adsorbent filter when near saturation and relatively high molecular weight contaminants that are trapped by the adsorbent filter even when near saturation. When the treatment fluid flows in the order of the photocatalyst unit and the adsorbent filter unit according to the present invention, the low molecular weight contaminants in the treatment fluid are decomposed and removed by the photocatalyst, so that the adsorbent filter unit removes the treatment fluid containing the high molecular weight contaminants. Can be processed. As a result, low-molecular-weight contaminants that are not necessarily suitable for adsorption removal by the adsorbent filter that do not come to the adsorbent filter unit without the photocatalyst unit do not reach the adsorbent filter unit. All in all, it can be devoted to high molecular weight contaminants suitable for adsorption removal there. This also leads to extending the useful life of the sorbent filter.
[0032]
If the fluid to be treated exclusively contains low molecular weight contaminants, the contaminants are decomposed and removed by the photocatalytic unit, and the adsorbent filter unit operates substantially without load. In such a case, the fluid to be treated can bypass the adsorbent filter unit after the treatment in the photocatalytic unit.
[0033]
If the fluid to be treated exclusively contains high molecular weight contaminants, the contaminants pass through the photocatalytic unit without substantial treatment to the adsorption filter unit where they are adsorbed and removed. In such a case, the fluid to be treated can bypass the photocatalytic unit. This bypass is advantageous in that it eliminates the possibility that the photocatalytic unit will be contaminated with contaminants that cannot be decomposed there.
[0034]
A dust filter unit can be arranged downstream of the adsorption filter unit. This unit not only contains particulate contaminants originally contained in the fluid to be treated introduced into the environmental control device, but also particulate foreign substances generated during processing in the environmental control device (for example, from the adsorbent filter). (Which may generate particulate debris during processing) also allows for the supply of clean fluids free of all types of contaminants. As the dust filter, an HEPA filter or an ULPA filter widely used for purifying air for a clean room can be used.
[0035]
The fluid purifying apparatus of the present invention can include a fluid transfer unit that enables the transfer of the fluid to be processed. When the fluid to be treated is a gas, a fan can be used as this means. Preferably, the fan is unitized and integrated with the photocatalyst unit, the adsorbent filter unit, and when including the dust filter, the dust filter unit. Due to the installation conditions of the device, the fan may be installed separately from other units. When the fluid to be treated is a liquid, a pump is generally used as the fluid transfer means. The pump can also be unitized and integrated with other units, or installed separately from them.
[0036]
The use of unitized (or modularized) components (a photocatalyst, an adsorbent filter, a dust filter, and a fluid transfer means) in the fluid purification apparatus of the present invention facilitates manufacture, assembly, maintenance, and inspection. There is an advantage. For example, by making the adsorbent filter unit and the dust filter unit so that the filter element can be attached and detached in a pull-out manner, replacement of the filter element can be facilitated.
[0037]
The fluid purification apparatus of the present invention can also include an analyzer (measurement monitor) for analyzing one or both of contaminants of the fluid to be treated and the fluid purified by the apparatus. Using the analysis data from the analyzer provided on the inlet side to the fluid purification device, the above-described switching for the selective introduction of the fluid to be treated into the photocatalyst unit or the adsorbent filter unit can be performed. Furthermore, the use of an analyzer provided on the outlet side of the fluid purifying device makes it possible to return the fluid to the upstream side for reprocessing if contaminants are still detected in the treated fluid. As the analyzer, a known analyzer effective for detecting a contaminant which is assumed to be contained in the fluid to be processed by the fluid purification device can be used.
[0038]
As an example, analysis using gas chromatography will be described. A gaseous treatment fluid containing low-boiling contaminants such as acetone and MEK and a high-boiling contaminant such as DBP and DOP is processed using a sample on the upstream side of the fluid purification apparatus, that is, on the inlet side of the treatment fluid. When analyzed by gas chromatography, a gas chromatogram containing both a peak of a low boiling component and a peak of a high boiling component as shown in FIG. 1 (a) is obtained. Purified through both filter units.
[0039]
As shown in FIG. 1 (b), when a low boiling point component is detected in the sample on the upstream side of the fluid purification device, the fluid to be treated is processed by the photocatalyst unit, and comes out of the photocatalyst unit. The fluid may optionally be bypassed without passing through the adsorbent filter unit. On the other hand, as shown in FIG. 1 (c), when a high boiling component is detected in the sample on the upstream side of the fluid purification device, the fluid to be treated is bypassed to the photocatalyst unit and directly to the adsorbent filter unit. It is possible to introduce. FIG. 1 (d) shows a gas chromatogram obtained at the outlet side of the fluid purification apparatus, in which only the background response is recorded, and no peak corresponding to the contaminant is seen. When a peak indicating that a part of the contaminant is contained in the fluid from the purification device is observed in the gas chromatogram, the fluid can be returned to the upstream side of the purification device.
[0040]
Changing the destination of the fluid to be processed or the processed fluid may be performed manually or automatically. In the automatic case, a control unit can be used that processes the signal from the analyzer and generates a signal that makes the change automatically.
[0041]
Next, the fluid purification device of the present invention will be further described with reference to the drawings, but the present invention is not limited thereto.
[0042]
FIG. 2 is a schematic diagram showing a combination of the photocatalyst unit 2 and the adsorbent filter unit 3 used in the fluid purification device of the present invention. As the fluid to be treated, for example, a gas typified by air in a clean room can be used, or pure water used in semiconductor device production equipment may be used. The fluid to be processed passes through this combination in the order of the photocatalyst unit 2 and the adsorbent filter 3.
[0043]
The photocatalyst unit 2 includes an ultraviolet lamp in a wavelength band of 150 to 450 nm, or a luminous body 4 associated with discharge, and TiO 2 supported on a support body surface such as a glass material. ₂ The photocatalyst 5 is included, and this unit can be manufactured to have a structure as shown in, for example, JP-A-2001-62253.
[0044]
The adsorbent filter unit 3 uses an adsorption filter suitable for adsorbing and removing contaminants in the fluid to be treated, such as activated carbon, a neutralizing reactant impregnated on activated carbon, or an ion exchange group such as ion exchange fiber. Be produced.
[0045]
Using this combination, contaminants such as an inorganic or organic gas and ozone gas can be removed.
[0046]
Adsorbent filters are usually based on activated carbon and tend to lose their ability to capture relatively low molecular weight organics such as acetone, methanol and ethanol, i.e. low boiling organics, as the amount of adsorption increases. It is in. For example, an adsorbent filter impregnated with a neutralizing reactant can adsorb small-molecular-weight organic substances such as acetone, methanol, and ethanol before the adsorbent filter is saturated as the amount of adsorption increases. And these substances will pass through the adsorbent filter unit. Organic substances, such as acetic acid, formic acid, and isopropyl alcohol (IPA), which have slightly higher molecular weights, may desorb after being adsorbed. Thus, these relatively low molecular weight organics are not very suitable for complete removal with adsorbent filters.
[0047]
On the other hand, the photocatalyst unit 2 decomposes pollutants by photocatalysis, and is excellent in decomposing organic substances having a small molecular weight such as acetone, methanol and ethanol, that is, organic substances having a low boiling point. Decomposition of organic substances having a relatively large molecular weight, such as organic substances having a high boiling point, has a problem in terms of decomposition efficiency.
[0048]
Therefore, first, the photocatalytic unit 2 decomposes and removes organic substances having a low molecular weight such as acetone, methanol, and ethanol, and organic substances having a slightly higher molecular weight such as acetic acid, formic acid, and isopropyl alcohol in the fluid to be treated. Then, the adsorbent filter unit 3 adsorbs and removes organic substances having a relatively high molecular weight, such as xylene, ethylbenzene, and cyclohexanone, which could not be decomposed and removed by the photocatalyst unit 2. The processing fluid can be efficiently processed and purified. Further, since the adsorbent filter unit 3 can be dedicated to the adsorption and removal of the contaminant having a relatively high molecular weight, the adsorption capacity of the adsorbent filter can be maintained for a long time.
[0049]
The operating conditions under which the photocatalyst unit 2 and the adsorbent filter unit 3 work effectively can be determined depending on the type of photocatalyst and adsorbent filter used in them.
[0050]
FIG. 3 shows an embodiment of the fluid purification apparatus of the present invention incorporating the combination of the photocatalyst unit 2 and the adsorbent filter unit 3 shown in FIG.
The apparatus 1 of this embodiment is configured by arranging and integrating the photocatalyst unit 2, the adsorbent filter unit 3, the unit 8 of the fluid transfer means, and the dust filter unit 9 in this order. From the dust removal filter unit 9. Such an apparatus 1 is provided, for example, on a wall surface or a ceiling surface of a clean room, or a wall surface or a ceiling surface of a production facility such as a semiconductor device, and is used for purifying air in a clean room as a fluid to be processed. can do. In the case where it is difficult to integrate the units due to the restriction of the installation place, it is also possible to install them separately instead of adjoining.
[0051]
In the apparatus 1 shown in FIG. 3, as the fluid transfer means of the unit 8, a fan can be used when the fluid to be treated is a gas, and a pump can be used when the fluid to be treated is a liquid. The unit 8 in the case where the fluid transfer means is a fan is not limited to the unit between the adsorbent filter 3 and the dust filter 9 shown in the drawing, and may be arranged, for example, on the upstream side of the photocatalyst unit 2. It is also possible to arrange at a position separated from the combination of 3, 9. Also in this case, the unit 8 of the fluid transfer means is connected, for example, to the upstream side of the photocatalyst unit 2 or the suction side is connected to the outlet side of the adsorbent filter unit 3, and the discharge side is connected to the inlet side of the dust filter. It is possible to connect. The unit 8 in the case where the fluid transfer means is a pump can also be arranged at any position, but is preferably arranged upstream of the photocatalyst unit 2. In both cases where the fluid to be treated is a gas or a liquid, the unit 8 is preferably installed upstream of the dust filter unit 9 because the fluid transfer means is a potential source of contamination.
[0052]
4 (a) to 4 (c) exemplify a typical positional relationship between the purification device 1 and the environment to be controlled when the fluid purification device 1 of the present invention is used as an environment control device. . FIG. 4A shows an example in which the purification device 1 is installed on a ceiling of a closed system manufacturing device or the work booth 11, and the working environment in the manufacturing device or the work booth 11 is sent by sending air purified by the purification device 1. Can be kept clean. FIG. 4B is an example in which the purification device 1 is installed adjacent to a closed system manufacturing device or the work booth 11, and is also used to keep the working environment in the manufacturing device or the work booth 11 in a clean state. be able to. This example can be adopted when there is no space for installing the purification apparatus 1 on the ceiling of the manufacturing apparatus or the work booth 11, and in some cases, the purification apparatus 1 is directly connected to the wall of the production apparatus or the work booth 11. Installation is also possible. 4A and 4B, if the manufacturing apparatus or the work booth 11 is replaced with a clean room, the work environment of the clean room can be controlled. FIG. 4C shows an example in which the purifying apparatus 1 is incorporated in an exhaust system from the manufacturing apparatus or the work booth 11 in the clean room, and the contaminant contained in the exhaust gas from the manufacturing apparatus or the work booth 11 is removed. And can be used to prevent cross-contamination of clean rooms. In this case, the working environment in the clean room is controlled cleanly, and as a result, the supply of the clean air to the manufacturing apparatus or the work booth 11 itself is performed as shown in FIG. Can improve the efficiency of another purifying device (not shown) installed as shown in the above, or particularly can contribute to prolonging the life of the adsorbent filter unit.
[0053]
The purifying apparatus of the present invention is installed on a transport trolley that requires a local clean storage unit for transporting wafers and the like, and this trolley is used in place of the transport means for wafers and the like, which has heretofore been a box transport means in general. It is also possible to use it.
[0054]
FIG. 5 shows a photocatalyst unit 2, an adsorbent filter unit 3, a fluid transfer unit 8 composed of a fan, a dust filter 9, and a contaminant concentration measurement monitor 15 for a gas to be treated, which has been described in the previous example. It can be used for environmental control of a clean room, which is composed of valves 11, 12, 13, 14 for switching the flow path of the gas to be treated, and a control unit 16 for switching the valves according to the concentration of pollutants. 1 shows a fluid purification device 10 of the present invention. The non-process gas in this case is air that may contain contaminants.
[0055]
For example, as the contaminant concentration measurement monitors 15 and 17, monitors for measuring the amounts of organic substances having a relatively small molecular weight, IPA, and organic substances having a relatively large molecular weight, cyclohexanone, which are considered to be a cause of contamination by organic substances in a clean room. Use
[0056]
When the contaminant concentration measuring monitor 15 detects that IPA is contained in the air of the gas to be treated introduced into the clean room, the valve 11 is opened and the valve 12 is closed by the signal from the control unit 16, and the photocatalyst is opened. Unit 2 decomposes and removes IPA. The gas from which the IPA has been removed by the photocatalyst unit 2 can also bypass the adsorbent filter unit 3 by closing the valve 13 and opening the valve 14 in response to a signal from the control unit 16. The gas from which the IPA has been removed is then supplied into the clean room by a fluid transfer unit 8 through a dust filter 9.
[0057]
When IPA is not detected in the air of the gas to be processed and cyclohexanone is detected, the valve 11 is closed and the valve 12 is opened by the signal from the control unit 16 to allow the gas to bypass the photocatalytic unit 2 and to adsorb the adsorbent. It is sent directly to the unit 3 and adsorbs and removes cyclohexanone with an adsorbent filter.
[0058]
When both IPA and cyclohexanone are detected during the intake of the gas to be treated, the valves 11 and 13 are opened, the valves 12 and 14 are closed, and the IPA is decomposed and removed by the photocatalytic unit 2, and then the cyclohexanone is adsorbed. Adsorption and removal are performed by the filter unit 3.
[0059]
The photocatalyst unit 2 receives the gas to be treated by opening the valve 11 when an organic substance having a small molecular weight suitable for decomposition and removal by the photocatalyst is contained in the gas to be treated, and closes the valve 11 otherwise. Thus, the gas to be treated can be bypassed, thereby contributing to prolonging the life of the ultraviolet lamp of the excitation light source or the illuminant accompanying the discharge, and reducing the number of times of regular cleaning or replacement. Similarly, it is possible to reduce the number of regular cleaning or replacement of the photocatalyst supported on the support.
[0060]
The adsorbent filter unit 3 always receives a gas having no organic matter having a small molecular weight and can bypass a gas having no organic matter having a large molecular weight to be treated by this unit. A reduction in the number of replacements of the adsorbent filter can be realized.
[0061]
The opening and closing control of the valves 11, 12, 13, and 14 based on the measurement result of the pollutant concentration measurement monitor 15 may be manually performed without using the control unit 16.
[0062]
Further, it is possible to additionally install a pollutant concentration measurement monitor 17 on the outlet side of the purification device 1. The measurement monitor 17 on the outlet side is effective as a means for confirming the life of the photocatalyst unit 2 or the adsorbent filter unit 3. When a large amount of organic matter is detected, the photocatalyst unit 2 is used in accordance with the type of the detected organic matter. Alternatively, it can be determined that the adsorbent filter unit 3 has deteriorated. The measurement result of the monitor 17 can be reflected in the change of the gas flow path by controlling the valves 11, 12, 13, and 14. Alternatively, it is possible to omit the pollutant concentration measurement monitor 15 on the inlet side of the purification device 1 and provide only the measurement monitor 17 on the outlet side.
[0063]
By using the pollutant concentration measurement monitor 17 capable of measuring ozone gas, the purifying apparatus 10 can be used for purifying gas containing ozone. Ozone oxidizes the surface of the semiconductor wafer and needs to be efficiently removed. Ozone is reduced to oxygen by the adsorbent filter 3 and removed. However, since the photocatalyst functions rather as an oxidizing agent, it can contribute to the generation of ozone but cannot contribute to its removal. Then, when the ozone gas is detected by the pollutant concentration measurement monitors 15 and 17, the valves 11, 13, and 14 are closed and the valve 12 is opened. Since the gas containing ozone flows to the adsorbent filter unit 3 by bypassing the photocatalyst unit 2, the ozone can be efficiently removed.
[0064]
Monitors that measure the total amount of organic substances may be used as the pollutant concentration measurement monitors 15 and 17, and the flow path of the gas may be changed based on the measurement results. This is because, for example, the type and amount of contaminants in the normal gas to be treated are determined, and as the other contaminants, a substance effective for treatment with the photocatalyst may be occasionally included in the gas to be treated. It is particularly effective in such cases.
[0065]
The contaminant concentration measurement monitors 15 and 17 may be installed when necessary, such as when fluctuations in the type and amount of contaminants in the gas to be processed are predicted. Alternatively, the contaminant concentration measurement monitors 15 and 17 may be installed in another place without being provided in the gas flow path, and a sample collected from the gas flow path may be measured by a measurement monitor installed in another place.
[0066]
Further, instead of the valves 11, 12, 13, and 14, it is also possible to use a damper or a slit-type opening / closing shutter. Further, the valves 13 and 14 need not be provided, and the same effect can be expected only by switching the valves 11 and 12.
[0067]
By installing the fluid purification device 10 in multiple stages, it is possible to perform more efficient purification. Further, if the fluid purification device 10 itself is placed in, for example, a stainless steel box, more efficient purification becomes possible.
[0068]
FIG. 6 shows the fluid purification apparatus 10 described with reference to FIG. 5 in which a circulation path from the outlet side of the dust filter unit 9 to the upstream side of the fluid purification apparatus and valves 18 and 19 for switching to the circulation path are provided. And a fluid purifying apparatus 10 'having an additional aspect. An example of purifying gas containing various contaminants using the purifying device 10 'will be described below.
[0069]
The first example is a quartz oscillator type in which air containing contaminants such as acetic acid and formic acid, which cause oxidation of a silicon wafer in the manufacture of semiconductor devices, is used as a gas to be treated and the total amount of contaminants (TOC) is measured. The film thickness monitor is used as the contaminant concentration measurement monitors 15 and 17. Switching between the valves 11, 12, 13, 14, 18, and 19 is automatically performed by a signal from the control unit 16 based on the TOC measurement result.
[0070]
The contaminant concentration of the gas to be processed is measured by the crystal oscillator type film thickness monitor 15. When the contaminant concentration is low, the valves 11 and 14 are opened, the valves 12 and 13 are closed, and the gas is purified by the photocatalyst unit 2. Normally, the valve 18 on the outlet side of the purification device 10 'is opened, and the valve 19 in the circulation path is closed. When the contaminant concentration is at the middle level, the valve 11 is closed, the valve 12 is opened, and the gas is purified by the adsorbent filter unit 3. When the contaminant concentration is high, the valves 11 and 13 are opened, the valves 12 and 14 are closed, and the gas is purified by both the photocatalyst unit 2 and the adsorbent filter unit 3.
[0071]
The contaminant concentration of the purified gas is monitored by the quartz crystal film thickness monitor 17. When the gas is purified only by the photocatalyst unit 2 and a contaminant is detected by the monitor 17, the valve 13 is opened and the valve 14 is closed to purify the gas by both the photocatalyst unit 2 and the adsorbent filter unit 3. The operation of the purification device 10 'is switched as described above. When the gas is purified only by the adsorbent filter unit 3 and contaminants are detected, the valves 11 and 13 are opened, the valves 12 and 14 are closed, and both the photocatalyst unit 2 and the adsorbent filter unit 3 are used. Switch operation to purify gas. When the gas is purified by both the photocatalyst unit 2 and the adsorbent filter unit 3 and a pollutant is detected, the valve 18 is closed, the valve 19 is opened to circulate the gas, and the purification is performed again.
[0072]
The second example is that NO as a pollutant in the gas to be treated _x , SO _x , Removes ozone. NO to be removed is displayed on the measurement monitors 15 and 17. _x , SO _x Or use a monitor to measure ozone. If there are two or more contaminants to be removed, prepare a measurement monitor for each contaminant.
[0073]
The measurement monitor 15 measures the contaminant concentration of the gas to be treated. When the contaminant concentration is high, the valve 11 is closed, the valve 12 is opened, and the gas is purified by the adsorbent filter unit 3. When the contaminant concentration is low, the valves 11 and 14 are opened, the valves 12 and 13 are closed, and the gas is purified by the photocatalyst unit 2. Normally, the valve 18 on the outlet side of the purification device 10 'is opened and the valve 19 is closed.
[0074]
The measurement monitor 17 monitors the contaminant concentration of the purified gas. When the gas is purified only by the photocatalyst unit 2 and contaminants are detected by the measurement monitor 17, the valve 13 is opened and the valve 14 is closed to purify the gas by both the photocatalyst unit 2 and the adsorbent filter unit 3. The operation of the purification device 10 'is switched to perform the operation. When the gas is purified only by the adsorbent filter unit 3 and contaminants are detected, the valves 11 and 13 are opened, the valves 12 and 14 are closed, and both the photocatalyst unit 2 and the adsorbent filter unit 3 are used. Switch operation to purify gas. When gas is purified by both the photocatalyst unit 2 and the adsorbent filter unit 3 and contaminants are detected, the valve 18 is closed, the valve 19 is opened to circulate the gas, and the purification process is performed again.
[0075]
A third example purifies the gas by removing ammonia. An ammonia measurement monitor is used for the measurement monitors 15 and 17.
[0076]
The measurement monitor 15 measures the ammonia concentration of the gas to be treated. When the ammonia concentration is high, the valves 11 and 13 are opened, the valves 12 and 14 are closed, and the gas is purified by both the photocatalyst unit 2 and the adsorbent filter unit 3. When the ammonia concentration is low, the valves 11 and 14 are opened and the valves 12 and 13 are closed to purify the gas with the photocatalyst unit 2, or the valves 11 and 14 are closed and the valve 12 is opened and the adsorbent filter unit 3 is used. Purify. Normally, the valve 18 on the outlet side of the purification device 10 'is opened and the valve 19 is closed.
[0077]
The measurement monitor 17 monitors the ammonia concentration of the purified gas. When ammonia is detected, the valve 18 is closed, the valve 19 is opened and the gas is circulated, and the gas is purified again. When the purification is performed by only the photocatalyst unit 2 or the adsorbent filter unit 3, the gas may be circulated, or the valve may be switched so that the unit whose operation has been stopped also operates. Alternatively, the gas may be circulated and the stopped unit may be operated.
[0078]
FIG. 7 shows an example in which switching of each of the valves 11, 12, 13, 14, 18, and 19 of the fluid purifying device 10 ′ described with reference to FIG. 6 is performed manually. In the fluid purification apparatus 10 "of this figure, a TENAX tube as a gas adsorption tube is used for the measurement monitors 15 and 17. The adsorbed organic gas is desorbed from the TENAX tube, and qualitatively and quantitatively analyzed by a gas chromatograph. Manually operate each valve based on the results.
[0079]
As a result of the analysis, when there is a large amount of organic gas having a small molecular weight, the valves 11 and 14 are opened, the valves 12 and 13 are closed, and the gas is purified only by the photocatalytic unit 2. When there is a large amount of organic gas having a large molecular weight, the valve 11 is closed and the valve 12 is opened, and the gas is purified only by the adsorbent filter unit 3. Normally, the valve 18 on the outlet side of the purification device 10 ″ is opened, and the valve 19 in the circulation path is closed.
[0080]
The measurement monitor 17 monitors the organic gas concentration of the purified gas. When an organic gas is detected, the valves 11 and 13 are opened, the valves 12 and 14 are closed, and the gas is purified by both the photocatalyst unit 2 and the adsorbent filter unit 3. When both the photocatalyst unit 2 and the adsorbent filter unit 3 purify the gas and the measurement monitor 17 detects an organic gas having a small molecular weight, the photocatalyst reaches its life and an organic gas having a large molecular weight is detected. At times, the adsorbent filter is deemed to have reached the end of its life, and the end of life is replaced. At the time of this replacement, the valves 18 to 14 are switched so that the gas is circulated through the normal (non-replacement) photocatalyst unit 2 or the adsorbent filter 3 by closing the valve 18 and opening the valve 19.
[0081]
In the fluid purifiers 10, 10 ′, and 10 ″ shown in FIGS. 5 to 7 that operate by switching the flow path of the gas to be treated, the dust filter unit 9 is disposed downstream of the adsorption filter unit 3, but this is not necessarily the case. It is not necessary to be located on the downstream side of the adsorbent filter unit 3. For example, a dust filter having the same function is provided in the gas flow path before branching by the valves 11 and 12 for switching the flow path of the gas to be processed. In this case, the dust filter may be used in place of the dust filter 9 in FIGS.5 to 7. Similarly, in the fluid purification devices 10, 10 ', 10 "of FIGS. The unit 8 is disposed between the adsorption filter unit 3 and the dust filter 9, but the position of the unit 8 is not limited to this. For example, the unit 8 is used for switching the flow path of the gas to be treated. It is also possible to place the treated gas flow path before branching in Bed 11,12.
[0082]
As described above, in the fluid purification apparatus of the present invention, a photocatalytic unit having a small molecular weight and excellent in decomposing and removing low-boiling organic substances is disposed in the first stage, and is used for adsorbing and removing high-molecular-weight and high-boiling organic substances. An excellent adsorbent filter is located in the second stage. As described with reference to FIGS. 5 to 7, the fluid purifying apparatus of the present invention can purify the fluid using one or both units according to the type of the contaminant in the fluid to be treated. Although it is possible, regardless of the type of contaminants in the fluid to be treated, the gas to be treated may be initially introduced exclusively into the adsorbent filter unit capable of adsorbing and removing low molecular weight, low boiling point organic substances. As purification proceeds and the adsorbent filter approaches saturation, low molecular weight organics begin to pass through the adsorbent filter and begin to be detected by the measurement monitor provided at the outlet side of the purifier. At this point, the flow path of the fluid to be treated is changed so as to be introduced from the photocatalyst unit, and the gas obtained by decomposing and removing low-molecular-weight organic substances can be supplied to the adsorbent filter unit. In this way, since the organic substance having a large molecular weight is supplied to the adsorbent filter unit, it becomes possible to further continue the purification of the gas by the adsorbent filter which is approaching saturation.
[0083]
Alternatively, it is also possible to always purify the fluid to be treated in the order of the photocatalyst unit and the adsorbent filter unit without changing the flow path of the fluid to be treated. Also in this case, the gas from which the low molecular weight organic matter has been decomposed and removed by the photocatalyst unit is supplied to the adsorbent filter unit, so that the maximum capacity of the adsorbent filter can be effectively used.
[0084]
As shown in FIG. 8, a constant temperature / humidity unit 22 using a chiller or the like can be added to the fluid purification device of the present invention. The fluid purifying device 21 shown in this figure is the same as the fluid purifying devices 10, 10 ′, and 10 ″ described with reference to FIGS. 5 to 7 except that the constant temperature / humidity unit 22 is included before the photocatalytic unit 2. The same reference numerals shown in Fig. 8 and used in Figs.5-7 denote the same units as those shown in Fig. 8. The apparatus of Fig. 8, of course, It can also include equipment (valves, measurement monitors, controls) shown in Figures 5 to 7 and not shown in this figure, the units can be arranged separately, the position of the fluid transfer means 8 can be changed. Is also the same as in the case of the purifying devices 10, 10 ′, 10 ″ described above.
[0085]
By using the constant temperature / humidity unit 22, it is possible to supply gas under conditions optimal for purifying the gas in the subsequent photocatalyst unit 2 and adsorbent filter unit 3.
[0086]
Further, the fluid purifying apparatus including the constant temperature / humidity unit 22 shown in FIG. 8 is also installed on a transport trolley that requires a local clean storage unit for transporting wafers and the like, and this trolley has been used as a box transport means. It can be used in place of a general means of transporting a wafer or the like.
[0087]
FIG. 9 shows an example in which the fluid purification device 31 of the present invention is used for controlling the environment inside the clean booth 30. This fluid purifying device 31 can also be configured in the same manner as the fluid purifying devices 10, 10 ′, 10 ″ described with reference to FIGS. 5 to 7, and the reference numerals shown in FIG. The same components as those shown therein indicate the same components as those shown in Fig. 8. The device shown in Fig. 8 also includes components (valves, control units) shown in Figs. The fact that the units can be arranged separately and the position of the fluid transfer means 8 can be changed are also the same as in the case of the purification devices 10, 10 ', 10 ".
[0088]
The purified air treated by the purification device 31 by introducing outside air is supplied to the clean booth 30. In order to increase the purification efficiency of the air in the clean booth 30, for example, 90% of the gas amount processed in the purification device 31 is taken out of the clean booth 30 through the circulation channel 33 together with the outside air introduced into the purification device 31. It may be. By this circulation, the purification efficiency of the purification device 31 can be increased (assuming that the same air as the clean air supplied from the purification device 31 to the clean booth 30 circulates, the amount of the circulation is 90 times the processing gas amount of the purification device 31). %, The purification efficiency of the purification device 31 is improved by a factor of 10).
[0089]
Further, a constant temperature / humidity unit as described with reference to FIG. 8 can be provided in front of the purification device 31.
[0090]
FIG. 10 shows an example in which the fluid purification device 41 of the present invention is used for controlling the environment of the opening 40 of the SMIF-box 42. This fluid purifying device 41 can also be configured in the same manner as the fluid purifying devices 10, 10 ′, 10 ″ described with reference to FIGS. 5 to 7, and the reference numerals shown in FIG. The same components as those shown are the same components as those shown in the figure.The device shown in Fig. 10 is also the components (valves, control units) shown in Figs. The fact that the units can be arranged separately and the position of the fluid transfer means 8 can be changed are also the same as in the case of the purification devices 10, 10 ', 10 ".
[0091]
The opening 40 of the SMIF-box 42 is a part for automatically taking in and out the wafer 48 and the like during the device manufacturing process from the SMIF-box 42, and the environmental purification is required only when the SMIF-box 42 is opened and closed. When necessary, the purified air from the purifying device 41 is supplied to the SMIF-box opening 40. When the supply is unnecessary, the entire amount is returned to the purifying device 41 by the circulation flow path 43 and circulated. This switching can be performed by a valve (not shown).
[0092]
Although the present invention has been described above, the features of the present invention will be described below with various aspects thereof.
(Supplementary Note 1) An apparatus for removing contaminants from a fluid to be treated and purifying the same, comprising: a photocatalyst capable of decomposing contaminants in a fluid to be treated; and a photocatalyst unit having an excitation light source for exciting the photocatalyst. An adsorbent filter unit capable of adsorbing contaminants in the fluid to be treated, the photocatalyst unit being disposed upstream of the adsorbent filter unit with respect to the flow direction of the fluid to be treated, and A fluid purification device comprising a dust removal filter unit arranged on the downstream side.
(Supplementary Note 2) The fluid purifying apparatus according to Supplementary Note 1, further comprising a switching unit that selectively introduces the target fluid into the photocatalyst unit or the adsorbent unit.
(Supplementary Note 3) An apparatus for removing contaminants from a fluid to be treated and purifying the same, comprising a photocatalyst capable of decomposing contaminants in the fluid to be treated, and a photocatalytic unit having an excitation light source for exciting the photocatalyst; An adsorbent filter unit capable of adsorbing contaminants in the fluid to be treated, a photocatalyst unit disposed upstream of the adsorbent filter unit with respect to a flow direction of the fluid to be treated, and A fluid purifying device comprising a switching means for selectively introducing a fluid into a unit or an adsorbent unit.
(Supplementary Note 4) When the fluid to be treated contains a contaminant suitable for removal by photocatalysis in the photocatalytic unit, the fluid to be treated is introduced into the photocatalytic unit, and the fluid to be treated is removed by the adsorbent unit. 4. The fluid purifying apparatus according to claim 2 or 3, wherein, when a contaminant suitable for removal by adsorption is contained, the fluid to be treated is introduced into the adsorbent filter unit.
(Supplementary note 5) The fluid purification apparatus according to supplementary note 4, wherein when the fluid to be treated contains a contaminant suitable for removal by photocatalysis in the photocatalytic unit, the gas treated by the photocatalytic unit bypasses the adsorbent unit. .
(Supplementary Note 6) When the concentration of the contaminant in the fluid to be treated is low, it is selectively purified by the photocatalytic unit, and when the concentration of the contaminant in the fluid to be treated is medium, it is selectively purified. The fluid purifying apparatus according to claim 2 or 3, wherein the fluid is purified by the adsorbent filter unit, and when the concentration of the contaminant in the fluid to be treated is high, it is purified by both the photocatalytic unit and the adsorbent filter unit. .
(Supplementary Note 7) When the contaminant is detected in the purified fluid, if the fluid to be treated is selectively purified by the photocatalytic unit, the adsorbent filter unit also purifies the fluid to be treated. As described above, when the operation of the fluid purifying device is switched, and when the fluid to be treated is selectively purified by the adsorbent filter unit, the operation of the fluid purifying device is switched so that the photocatalytic unit also purifies the gas to be treated. 7. The fluid purifying apparatus according to claim 6, wherein when both the photocatalytic unit and the adsorbent filter unit purify the fluid to be treated, the fluid is circulated and the fluid purifying apparatus again performs the purification process.
(Supplementary Note 8) When one type of contaminant is to be removed by the fluid purifying device and the concentration of the contaminant in the fluid to be treated is high, the contaminant is removed by both the photocatalyst unit and the adsorbent filter unit. 4. The fluid purifying apparatus according to claim 2, wherein the processing fluid is purified, and when the concentration of the pollutant is low, the fluid to be processed is purified by one of the photocatalyst unit and the adsorbent filter unit.
(Supplementary Note 9) In the case where purification is performed by both the photocatalyst unit and the adsorbent filter unit, when the contaminant is detected in the purified fluid to be treated, the fluid to be treated is circulated. 8. The fluid purifying apparatus according to claim 8, wherein
(Supplementary Note 10) If the contaminant is detected in the treated fluid that has been purified in one of the photocatalyst unit and the adsorbent filter unit, the fluid to be treated is removed. The fluid according to claim 8, wherein the fluid is circulated, the unit that has not been purified is also used for purification, or the unit that circulates the fluid to be treated and the unit that has not been purified is also used for purification. Purification device.
(Supplementary note 11) The fluid purifying apparatus according to Supplementary note 2 or 3, wherein the switching unit is an automatic unit.
(Supplementary note 12) The fluid purifying apparatus according to supplementary note 2 or 3, wherein the switching means is a manual type means.
(Supplementary note 13) The fluid purifying means according to supplementary note 2, further comprising a fluid transfer unit for transferring the fluid to be processed.
(Supplementary note 14) The fluid purifying apparatus according to supplementary note 13, wherein the fluid transfer means is located between the adsorbent filter unit and the dust filter unit.
(Supplementary note 15) The fluid purifying means according to supplementary note 3, further comprising a fluid transfer unit for transferring the fluid to be processed.
(Supplementary note 16) Supplementary note 15, further comprising a dust filter unit disposed downstream of the adsorbent filter unit, wherein the fluid transfer unit is located between the adsorbent filter unit and the dust filter unit. A fluid purifying device according to claim 1.
[0093]
【The invention's effect】
As described above, according to the present invention, the efficient use of the photocatalyst makes it possible to extend the life of the adsorbent filter and to use a fluid removing device with an increased efficiency of removing contaminants, and it is possible to use a fluid removing device such as a clean room. It is possible to easily control the environment of the space where the environment control is indispensable.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating gas chromatograms obtained for various gases.
FIG. 2 is a diagram schematically showing a combination of a photocatalyst unit and an adsorbent filter unit used in the fluid purification device of the present invention.
FIG. 3 is a diagram illustrating one embodiment of the fluid purification device of the present invention.
FIG. 4 is a diagram showing an example of a usage form of the fluid purification device of the present invention.
FIG. 5 is a diagram illustrating another embodiment of the fluid purification device of the present invention.
FIG. 6 is a diagram illustrating another embodiment of the fluid purification device of the present invention.
FIG. 7 is a diagram illustrating still another embodiment of the fluid purification device of the present invention.
FIG. 8 is a diagram illustrating still another embodiment of the fluid purification device of the present invention.
FIG. 9 is a diagram showing an example in which the fluid purification device of the present invention is used for controlling the environment in a clean booth.
FIG. 10 is a diagram showing an example in which the fluid purification device of the present invention is used for environmental control of an opening of a SMIF-box.
[Explanation of symbols]
1, 10, 10 ', 10 ", 21, 31, 41 ... fluid purifying device
2. Photocatalytic unit
3. Adsorbent filter unit
8 Unit of fluid transfer means
9 Dust removal filter unit
11, 12, 13, 14, 18, 19 ... valves
15, 17… Pollutant concentration measurement monitor
16 ... Control unit

Claims (10)

An apparatus for removing contaminants from a fluid to be treated and purifying the same, comprising: a photocatalyst capable of decomposing contaminants in the fluid to be treated; a photocatalyst unit having an excitation light source for exciting the photocatalyst; An adsorbent filter unit capable of adsorbing contaminants therein, wherein the photocatalyst unit is disposed upstream of the adsorbent filter unit with respect to the flow direction of the fluid to be treated, and further disposed downstream of the adsorbent filter unit. A fluid purification device comprising a dust filter unit formed as described above. The fluid purifying apparatus according to claim 1, further comprising a switching unit that selectively introduces the fluid to be processed into the photocatalytic unit or the adsorbent unit. An apparatus for removing contaminants from a fluid to be treated and purifying the same, comprising: a photocatalyst capable of decomposing contaminants in the fluid to be treated; a photocatalyst unit having an excitation light source for exciting the photocatalyst; An adsorbent filter unit capable of adsorbing contaminants therein, the photocatalyst unit being disposed upstream of the adsorbent filter unit with respect to the flow direction of the fluid to be treated, and further comprising a photocatalyst unit or adsorbent for the fluid to be treated. A fluid purifying device comprising switching means for selectively introducing the fluid into a unit. When the target fluid contains a contaminant suitable for removal by photocatalysis in the photocatalytic unit, the target fluid is introduced into the photocatalytic unit, and the target fluid is removed by adsorption in the adsorbent unit. The fluid purifying apparatus according to claim 2, wherein the fluid to be treated is introduced into the adsorbent filter unit when a suitable contaminant is contained. The fluid purifying apparatus according to claim 4, wherein when the fluid to be treated contains a contaminant suitable for removal by photocatalysis in the photocatalytic unit, the gas treated by the photocatalytic unit bypasses the adsorbent unit. When the concentration of the contaminant in the fluid to be treated is low, it is selectively purified by the photocatalytic unit, and when the concentration of the contaminant in the fluid to be treated is at a medium level, it is selectively purified by the adsorbent. 4. The fluid purifying apparatus according to claim 2, wherein the purifying is performed by a filter unit, and when the concentration of the contaminant in the fluid to be treated is high, the contaminant is purified by both the photocatalytic unit and the adsorbent filter unit. In the case where the contaminant is detected in the purified fluid, if the fluid to be treated is selectively purified by the photocatalytic unit, the fluid purification is performed so that the adsorbent filter unit also purifies the fluid to be treated. When the operation of the apparatus is switched, and when the fluid to be treated is selectively purified by the adsorbent filter unit, the operation of the fluid purification device is switched so that the photocatalyst unit also purifies the gas to be treated, 7. The fluid purifying apparatus according to claim 6, wherein when both the fluid and the adsorbent filter unit purify the fluid to be treated, the fluid is circulated and the fluid purifying apparatus again performs the purification process. When the type of contaminant to be removed by the fluid purifying device is one and the concentration of the contaminant in the target fluid is high, the target fluid is purified by both the photocatalytic unit and the adsorbent filter unit. 4. The fluid purifying apparatus according to claim 2, wherein when the concentration of the contaminant is low, the fluid to be treated is purified by one of the photocatalytic unit and the adsorbent filter unit. 5. 9. When the contaminant is detected in the purified fluid to be processed, when both the photocatalyst unit and the adsorbent filter unit perform purification, the fluid to be processed is circulated. A fluid purifying device according to claim 1. In the case where the purification is performed in one of the photocatalyst unit and the adsorbent filter unit, when the contaminant is detected in the purified fluid to be treated, the fluid to be treated is circulated, 9. The fluid purification apparatus according to claim 8, wherein the unit that has not been purified is also used for purification, or the unit that has not been purified by circulating the fluid to be treated is also used for purification.

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