JP4439674B2 - Deionized water production equipment - Google Patents

Description

【０００１】
【発明の属する技術分野】
本発明は、半導体製造分野、医製薬製造分野、原子力や火力等の発電分野、食品工業などの各種の産業又は研究所施設において使用され、高純度の水質をより安定して供給できる省電力型電気式脱イオン水製造装置を有する脱イオン水製造装置に関するものである。
【０００２】
【従来の技術】
脱イオン水を製造する方法として、従来からイオン交換樹脂に被処理水を通して脱イオンを行う方法が知られているが、この方法ではイオン交換樹脂がイオンで飽和されたときに薬剤によって再生を行う必要があり、このような処理操作上の不利な点を解消するため、近年、薬剤による再生が全く不要な電気式脱イオン法による脱イオン水製造方法が確立され、実用化に至っている。
【０００３】
図８はその従来の典型的な電気式脱イオン水製造装置の模式断面図を示す。図８に示すように、カチオン交換膜１０１及びアニオン交換膜１０２を離間して交互に配置し、カチオン交換膜１０１とアニオン交換膜１０２で形成される空間内に一つおきにイオン交換体１０３を充填して脱塩室とする。脱塩室の被処理水流入側（前段）にはアニオン交換樹脂１０３ａが充填され、脱塩室の被処理水流出側（後段）にはカチオン交換樹脂とアニオン交換樹脂の混合イオン交換樹脂１０３ｂが充填されている。また、脱塩室１０４のそれぞれ隣に位置するアニオン交換膜１０２とカチオン交換膜１０１で形成されるイオン交換体１０３を充填していない部分は濃縮水を流すための濃縮室１０５とする。
【０００４】
また、脱塩室の一側に陰極１０９を配設すると共に、他端側に陽極１１０を配設する。なお、前述したスペーサーを挟んだ位置が濃縮室１０５であり、また両端の濃縮室１０５の両外側に必要に応じカチオン交換膜１０１、アニオン交換膜１０２、あるいはイオン交換性のない単なる隔膜等の仕切り膜を配設し、仕切り膜で仕切られた両電極１０９、１１０が接触する部分をそれぞれ陰極室１１２及び陽極室１１３とする。このように、従来の電気式脱イオン水製造装置においては、濃縮室の数は脱塩室の数より１つ多い形態のものであるか、あるいは両端に濃縮室を仕切り膜無しで電極室とした場合、１つ少ないものであった。
【０００５】
このような電気式脱イオン水製造装置によって脱イオン水を製造する場合を図８を参照して説明する。すなわち、陰極１０９と陽極１１０間に直流電流を通じ、また、被処理水流入ライン１１１から被処理水が流入すると共に、濃縮水流入ライン１１５から濃縮水が流入し、且つ電極水流入ライン１１７、１１７からそれぞれ電極水が流入する。被処理水流入ライン１１１から流入した被処理水は脱塩室１０４を流下し、先ず、前段のアニオン交換樹脂１０３ａを通過する際、塩酸イオンや硫酸イオンなどのアニオン成分が除去され、次に、後段のカチオン交換樹脂及びアニオン交換樹脂の混合イオン交換樹脂１０３ｂを通過する際、マグネシウムやカルシウムなどのカチオン成分が除去される。濃縮水流入ライン１１５から流入した濃縮水は各濃縮室１０５を上昇し、カチオン交換膜１０１及びアニオン交換膜１０２を介して移動してくる不純物イオンを受取り、不純物イオンを濃縮した濃縮水として濃縮水流出ライン１１６から流出され、さらに電極水流入ライン１１７、１１７から流入した電極水は電極水流出ライン１１８、１１８から流出される。従って、脱イオン水流出ライン１１４から脱塩水が得られる。
【０００６】
このような電気式脱イオン水製造装置を使用して被処理水中の不純物イオンを省電力で除去するために、電気式脱イオン水製造装置の電気抵抗を低減する種々の試みがなされている。この場合、脱塩室においては、脱塩室に使用されるイオン交換体の充填方法や充填量が要求される処理水の水質によって決定されるため、脱塩室の電気抵抗を低減させるには限界がある。そこで、濃縮室の電気抵抗を低減するための対策が採られることが多い。例えば、特開平９−２４３７４号公報には、濃縮室に電解質を添加供給して濃縮室における電気抵抗を低減する方法が開示されている。また、濃縮水の循環によって導電率の上昇を促進し、濃縮室の電気抵抗を低減する方法も多数報告されている。
【０００７】
【発明が解決しようとする課題】
しかしながら、濃縮室に電解質を添加供給して濃縮室の電気抵抗を低減する方法は、電解質を濃縮室へ供給するためのポンプ、薬剤貯留タンク及び供給配管などを設置しなければならず、設置面積の増加、設置コストの上昇などを招く、また、定期的に薬剤の補給や管理を行わなければならず、連続再生型装置であるにもかかわらず人手がかかるという問題がある。また、濃縮水の循環によって導電率の上昇を促進し、濃縮室の電気抵抗を低減する方法は、濃縮水中に含まれるカルシウムやマグネシウムなどの硬度成分も濃厚となりスケールの発生を促進して、結果的に電気抵抗の上昇を招来するという問題がある。
【０００８】
一方、電気式脱イオン水製造装置の被処理水としては、工業用水、水道水、脱イオン水を用いた生産工程からの回収水等が単独あるいは混合して使用されている。工業用水や水道水は季節や天候に起因する水質変動がある。特に、渇水や雨量が水質変動の要因となる。また、生産工程からの回収水は活性炭、イオン交換、逆浸透膜装置などの処理を経た後、被処理水として利用されるが、使用薬品の混入、微量不純物の混入など生産工程の変動に起因する水質変動がある。この場合、電気式脱イオン水製造装置の前段に活性炭、イオン交換、逆浸透膜装置などの前処理を強化して対処することも考えられるが、単に、同一位置（前処理）での補強だけでは上記のような水質変動に対応できず、電気式脱イオン水製造装置の処理水の水質低下を安定して抑制することはできない。また、運転開始当初は、処理水の使用量が急速に増大し、大流量の被処理水が脱塩室に流入する場合があるが、このような場合にも処理水の水質を低下させることなく、高純度の水質を有する処理水を安定して供給する必要がある。
【０００９】
従って、本発明の目的は、濃縮水へ薬剤を添加することなく、電気式脱イオン水製造装置の構造面からの抜本的な改善により電気抵抗を低減すると共に、被処理水の供給量増大や被処理水の水質悪化に対応でき、高純度の水質をより安定して供給できる省電力型電気式脱イオン水製造装置を利用した脱イオン水製造装置を提供することにある。
【００１０】
【課題を解決するための手段】
かかる実情において、本発明者らは鋭意検討を行った結果、（１）枠体の一側にカチオン交換膜が封着され、他側にアニオン交換膜が封着された従来の脱塩室構造において、このカチオン交換膜とアニオン交換膜の間にさらに、脱塩室を２分割する中間イオン交換膜を配設して、２つの小脱塩室を隣合わせに有する脱塩室とし、前記カチオン交換膜、アニオン交換膜を介して脱塩室の両側に濃縮室を設け、これらの脱塩室及び濃縮室を陽極と陰極の間に配置し、電圧を印加しながら被処理水を一方の小脱塩室に流入させ、該小脱塩室の流出水を他方の小脱塩室に流入させると共に、濃縮室に濃縮水を流入して被処理水中の不純物イオンを除去し、脱イオン水を製造するようにすれば、イオン交換体が充填された脱塩室１つ当たりの濃縮室の数を従来の約半分にすることができ、電気式脱イオン水製造装置の電気抵抗を著しく低減できること、（２）このような電気式脱イオン水製造装置の２つの小脱塩室を接続する配管途中に加圧ポンプを設置し、下流側の小脱塩室への流入水の圧力を高めて供給すれば、下流側の小脱塩室内圧力は上流側の小脱塩室内圧力より常に高めることができ、被処理水の供給量増大に伴い上流側の小脱塩室内圧力が上昇しても上流側小脱塩室から下流側小脱塩室へのイオンの移動や液の漏洩などが防止できること、（３）また、このような電気式脱イオン水製造装置の２つの小脱塩室を接続する配管途中に逆浸透膜装置、紫外線酸化装置などを設置すれば、被処理水からの除去が困難とされるホウ素や有機物（ＴＯＣ）が極めて効率よく除去できること、などを見出し、本発明を完成するに至った。
【００１１】
すなわち、請求項１の発明（１）は、一側のカチオン交換膜、他側のアニオン交換膜及び当該カチオン交換膜と当該アニオン交換膜の間に位置する中間イオン交換膜で区画される２つの小脱塩室にイオン交換体を充填して脱塩室を構成し、前記カチオン交換膜、アニオン交換膜を介して脱塩室の両側に濃縮室を設け、これらの脱塩室及び濃縮室を陽極と陰極の間に配置して形成され、前記一方の小脱塩室の流出管は他方の小脱塩室の流入管に接続され、該２つの小脱塩室を接続する配管途中にポンプを設置してなる電気式脱イオン水製造装置を有することを特徴とする脱イオン水製造装置を提供するものである。かかる構成を採ることにより、電気式脱イオン水製造装置ではイオン交換体が充填された脱塩室１つ当たりの濃縮室の数を従来の約半分にすることができ、電気抵抗を著しく低減できる。また、２つの小脱塩室のうち、少なくとも１つの脱塩室に充填されるイオン交換体を例えばアニオン交換体のみ、又はカチオン交換体のみ等の単一イオン交換体もしくはアニオン交換体とカチオン交換体の混合イオン交換体とすることができ、イオン交換体が充填された脱塩室の厚さを電気抵抗を低減し、且つ高い電流効率を得る最適な厚さに設定することができる。また、運転当初、処理水の使用量が増大して被処理水の供給量の増加や閉塞などにより上流側の小脱塩室内の圧力が上昇しても下流側の小脱塩室内圧力を上流側の小脱塩室内圧力より常に高めることができ、上流側小脱塩室から下流側小脱塩室へのイオンの移動や液の漏洩などが防止でき、高純度の水質をより安定して供給できる。さらに、上流側の小脱塩室より下流側の小脱塩室の流量を多くすることができる。例えば、使用点（ユースポイント）で使用後の水が十分な水質で簡単な処理で回収できる場合や、ユースポイントで使用されることなく循環回収される場合にはこれらの回収水を上流側の小脱塩室を経ずに直接下流側の小脱塩室に供給することができる。
【００１２】
請求項２の発明（２）は、一側のカチオン交換膜、他側のアニオン交換膜及び当該カチオン交換膜と当該アニオン交換膜の間に位置する中間イオン交換膜で区画される２つの小脱塩室にイオン交換体を充填して脱塩室を構成し、前記カチオン交換膜、アニオン交換膜を介して脱塩室の両側に濃縮室を設け、これらの脱塩室及び濃縮室を陽極と陰極の間に配置して形成され、前記一方の小脱塩室の流出管は他方の小脱塩室の流入管に接続され、該２つの小脱塩室を接続する配管途中に逆浸透膜装置、紫外線酸化装置及び脱気膜装置から選ばれる１種以上を設置してなる電気式脱イオン水製造装置を有することを特徴とする脱イオン水製造装置を提供するものである。かかる構成を採ることにより、前記中間イオン交換膜と前記他側のアニオン交換膜で区画される一方の小脱塩室に充填されるイオン交換体を、アニオン交換体とし、前記一側のカチオン交換膜と前記中間イオン交換膜で区画される他方の小脱塩室に充填されるイオン交換体を、カチオン交換体とアニオン交換体の混合体とした場合、上流側（一方）の小脱塩室でアニオン成分が除去され、この小脱塩室の流出水はアルカリ側となる。このため、ホウ素に関しては、被処理水中のホウ素の解離が進むか、あるいは何らかの電気的処理を受けたことによりホウ素の存在形態が変化し、次いで流入する逆浸透膜装置でホウ素の除去効率が一層高まる。また、有機物に関しても同様に被処理水中の有機物の解離が進むか、あるいは何らかの電気的処理を受けたことにより有機物の存在形態が変化し、次いで流入するＵＶoxで酸化し易くなる。また、電気式脱イオン水製造装置の第２小脱塩室で有機物の一部が除去されるため、次いで流入するＵＶoxでは残存の有機物を酸化すればよく、除去効率が向上する。従って、渇水などの自然現象や工場の生産工程からの不純物混入など被処理水の水質が悪化しても対応可能となる。
【００１３】
請求項３の発明（３）は、前記電気式脱イオン水製造装置の後段に、限外濾過膜装置又は精密濾過膜装置を設置し、前記電気式脱イオン水製造装置の処理水中の微粒子を更に除去することを特徴とする前記（１）又は（２）記載の脱イオン水製造装置を提供するものである。かかる構成を採ることにより、前記発明と同様の効果を奏する他、逆浸透膜装置や電気式脱イオン水製造装置で除去することができない被処理水中の微粒子を除去することができる。
【００１４】
請求項４の発明（４）は、前記中間イオン交換膜と前記他側のアニオン交換膜で区画される一方の小脱塩室に充填されるイオン交換体は、アニオン交換体であり、前記一側のカチオン交換膜と前記中間イオン交換膜で区画される他方の小脱塩室に充填されるイオン交換体は、カチオン交換体とアニオン交換体の混合体であることを特徴とする前記（１）又は（２）の脱イオン水製造装置を提供するものである。かかる構成を採ることにより、アニオン成分を多く含む被処理水、特にシリカ、炭酸等の弱酸性成分を多く含む被処理水を十分に処理することが可能となると共に、２つの小脱塩室を接続する配管途中に逆浸透膜装置や紫外線酸化装置を設置すれば、被処理水中のホウ素や有機酸を効率的に除去できる。
【００１５】
【発明の実施の形態】
本発明で使用する電気式脱イオン水製造装置の１例を図１を参照して説明する。図１はその電気式脱イオン水製造装置の模式図である。図１に示すように、カチオン交換膜３、中間イオン交換膜５及びアニオン交換膜４を離間して交互に配置し、カチオン交換膜３と中間イオン交換膜５で形成される空間内にイオン交換体８を充填して第１小脱塩室ｄ₁ 、ｄ₃ 、ｄ₅ 、ｄ₇ を形成し、中間イオン交換膜５とアニオン交換膜４で形成される空間内にイオン交換体８を充填して第２小脱塩室ｄ₂ 、ｄ₄ 、ｄ₆ 、ｄ₈ を形成し、第１小脱塩室ｄ₁ と第２小脱塩室ｄ₂ で脱塩室Ｄ₁ 、第１小脱塩室ｄ₃ と第２小脱塩室ｄ₄ で脱塩室Ｄ₂ 、第１小脱塩室ｄ₅ と第２小脱塩室ｄ₆ で脱塩室Ｄ₃ 、第１小脱塩室ｄ₇ と第２小脱塩室ｄ₈ で脱塩室Ｄ₄ とする。また、脱塩室Ｄ₂ 、Ｄ₃ のそれぞれ隣に位置するアニオン交換膜４とカチオン交換膜３で形成されるイオン交換体８を充填していない部分は濃縮水を流すための濃縮室１とする。これを順次に併設して図中、左より脱塩室Ｄ₁ 、濃縮室１、脱塩室Ｄ₂ 、濃縮室１、脱塩室Ｄ₃ 、濃縮室１、脱塩室Ｄ₄ を形成する。また、中間膜を介して隣合う２つの小脱塩室において、第２小脱塩室の処理水流出ライン１２は集合配管１２ａ通じて貯槽２１に接続され、貯槽２７から延出されるポンプ２５を有する流出配管２３はバルブ２１を有する配管１３ａを通じて第１小脱塩室の被処理水流入ライン１３に連接されている。また、貯槽２７には流出配管２３のバルブ２２を有する戻り配管２４と、窒素ガス配管２６が接続されている。記号Ｐ１は第２小脱塩室（上流側小脱塩室）の入口圧力を測定する圧力計を、Ｐ２は第２小脱塩室の出口圧力を測定する圧力計を、Ｐ３は第１小脱塩室（下流側小脱塩室）の入口圧力を測定する圧力計を、Ｐ４は第１小脱塩室の出口圧力を測定する圧力計をそれぞれ示す。
【００１６】
上記のような脱塩室は２つの内部がくり抜かれた枠体と３つのイオン交換膜によって形成される脱イオンモジュールからなる。すなわち、図では省略するが、第１枠体の一側にカチオン交換膜を封着し、第１枠体のくり抜かれた部分にイオン交換体を充填し、次いで、第１枠体の他方の部分に中間イオン交換膜を封着して第１小脱塩室を形成する。次に中間イオン交換膜を挟み込むように第２枠体を封着し、第２枠体のくり抜かれた部分にイオン交換体を充填し、次いで、第２枠体の他方の部分にアニオン交換膜を封着して第２小脱塩室を形成する。なお、イオン交換膜は比較的柔らかいものであり、第１枠体、第２枠体内部にイオン交換体を充填してその両面をイオン交換膜で封着した時、イオン交換膜が湾曲してイオン交換体の充填層が不均一となるのを防止するため、第１枠体、第２枠体の空間部に複数のリブを縦設する。また、図では省略するが、第１枠体、第２枠体の上方部に被処理水の流入口又は処理水の流出口が、また枠体の下方部に被処理水の流出口又は処理水の流入口が付設されている。このような脱イオンモジュールの複数個をその間に図では省略するスペーサーを挟んで、並設した状態が図１に示されたものであり、並設した脱イオンモジュールの一側に陰極６を配設すると共に、他端側に陽極７を配設する。なお、前述したスペーサーを挟んだ位置が濃縮室１であり、また両端の脱塩室Ｄの両外側に必要に応じカチオン交換膜、アニオン交換膜、あるいはイオン交換性のない単なる隔膜等の仕切り膜を配設し、仕切り膜で仕切られた両電極６、７が接触する部分をそれぞれ電極室２、２としてもよい。
【００１７】
このような電気式脱イオン水製造装置によって脱イオン水を製造する場合、以下のように操作される。すなわち、陰極６と陽極７間に直流電流を通じ、また被処理水流入ライン１１から被処理水が流入すると共に、濃縮水流入ライン１５から濃縮水が流入し、かつ電極水流入ライン１７、１７からそれぞれ電極水が流入する。被処理水流入ライン１１から流入した被処理水は第２小脱塩室ｄ₂ 、ｄ₄ 、ｄ₆ 、ｄ₈ を流下し、例えばアニオン交換体８１の充填層を通過する際に不純物イオンが除去される。更に、第２小脱塩室の処理水流出ライン１２を通った流出水は貯槽２７に流入する。そして、窒素シールにより外部ガス、特に空気中の炭酸ガスの混入を遮断した状態で貯留される。ここでタンクのシールに利用する窒素源は、ガスボンベの窒素、液体窒素、ガス分離膜又は圧力スイング吸着法により空気から炭酸ガスを除去した改質空気又はさらに酸素を除去した窒素ガスを利用できる。貯留された流出水はポンプ２５で昇圧された後、第１小脱塩室の被処理水流入ライン１３を通って第１小脱塩室ｄ₁ 、ｄ₃ 、ｄ₅ 、ｄ₇ を流下し、ここでも例えば、カチオン交換体とアニオン交換体の混合イオン交換体８２の充填層を通過する際に不純物イオンが除去され、脱イオン水が脱イオン水流出ライン１４から得られる。また、濃縮水流入ライン１５から流入した濃縮水は各濃縮室１を上昇し、カチオン交換膜３及びアニオン交換膜４を介して移動してくる不純物イオンを受取り、不純物イオンを濃縮した濃縮水として濃縮水流出ライン１６から流出され、さらに電極水流入ライン１７、１７から流入した電極水は電極水流出ライン１８、１８から流出される。この場合、Ｐ３の圧力≧Ｐ１の圧力、Ｐ４の圧力≧Ｐ２の圧力の双方を満足するように、ポンプ２５の供給圧力及びバルブ２１、２２の開度が決定される。上述の操作によって、被処理水中の不純物イオンは電気的に除去されると共に、処理水の使用量変動、特に大流量の被処理水を供給するに伴い第２小脱塩室内圧力（Ｐ１）が上昇しても、第１小脱塩室内圧力は第２小脱塩室内圧力より常に高めることができ、第２小脱塩室から第１小脱塩室へのイオンの移動や液の漏洩などが防止できる。Ｐ３とＰ１の圧力差及びＰ４とＰ２の圧力差は０．１５MPa(１．５kg/cm²） (ゲージ圧) 以下とすることが好ましい。この圧力差が大きすぎると逆に第１小脱塩室から第２小脱塩室への液の漏洩が起こり易く、またイオン交換膜の変形が大きくなる。
【００１８】
図１において、例えば貯槽２７やポンプ２５を省略し、配管１２ａと配管１３ａを直接接続し、第２小脱塩室の流出水をそのまま第１小脱塩室の流入水とすると、被処理水の流量が増大し第２小脱塩室の圧力が増大した場合、第２小脱塩室と第１小脱塩室が隣接し、しかも第２小脱塩室の流出水が第１小脱塩室へ直接供給される構造から、圧力は第２小脱塩室の方が第１小脱塩室より必ず大となり、第２小脱塩室から第１小脱塩室へイオンや液の漏洩が起こることがある。また、このような漏洩が起こると小脱塩室中の不純物濃度は第２小脱塩室の方が第１小脱塩室より必ず大であるため第１小脱塩室の流出水（脱イオン水）の水質は低下してしまう、という問題がある。しかし、図１に示すように、２つの小脱塩室を接続する配管途中に昇圧ポンプを設置し、Ｐ１〜Ｐ４の圧力を上記の関係を満たすように運転してやれば、被処理水の供給量増大に伴う上記の問題を解決することができる。また、図１において、貯槽２７には図では省略する別系統からの流入配管を接続してもよい。これにより、例えば、ユースポイントで使用後の水が十分な水質で簡単な処理で回収できる場合や、ユースポイントで使用されることなく循環回収される場合にはこれらの回収水を上流側の小脱塩室を経ずに直接下流側の小脱塩室に供給することができる。
【００１９】
本実施の形態例において、中間のイオン交換膜としては、カチオン交換膜又はアニオン交換膜の単一膜、あるいはアニオン交換膜、カチオン交換膜の両方を配置したとした複式膜のいずれであってもよい。装置上部又は装置下部にアニオン交換膜又はカチオン交換膜とした複式膜とする場合、アニオン交換膜及びカチオン膜のそれぞれの高さ（面積）は被処理水の水質又は処理目的などによって適宜決定される。また、単一膜を使用する場合、被処理水中から除去したいイオン種に応じてイオン交換膜が決定される。
【００２０】
第１小脱塩室又は第２小脱塩室の厚さは特に制限されず、第１小脱塩室又は第２小脱塩室に充填されるイオン交換体の種類と充填方法によって、最適な厚さを決定すればよい。従って、第１小脱塩室の厚さを３mm、第２小脱塩室の厚さを６mmとして、全体の厚さ、すなわち脱塩室の厚さを９mmとしてもよい。このように、複数の脱塩室と濃縮室を交互に配置し、脱塩室の両側に配されるカチオン交換膜とアニオン交換膜で区画される脱塩室の厚みは、従来のものよりも厚くでき、１．５〜１８mm範囲、好適には、６．５〜１５mm、更に好適には９〜１３mmの範囲で適宜決定される。
【００２１】
また、脱塩室に充填されるイオン交換体としては、特に制限されず、アニオン交換体（以下、「Ａ」とも言う）単床、カチオン交換体（以下、「Ｋ」とも言う）単床及びアニオン交換体とカチオン交換体の混床（以下、「Ｋ／Ａ」とも言う）又はこれらの組合せのものが挙げられる。また、イオン交換体としては、イオン交換樹脂、イオン交換繊維などイオン交換機能を有する物質であればいずれでもよく、また、それらを組合せたものであってもよい。
【００２２】
また、被処理水の第１小脱塩室及び第２小脱塩室での流れ方向は、特に制限されず、上記実施の形態例の他、第１小脱塩室と第２小脱塩室での流れ方向が異なっていてもよい。また、被処理水が流入する小脱塩室は、上記実施の形態例の他、先ず、被処理水を第１脱塩室に流入させ、流下した後、第１脱塩室の流出水を第２脱塩室に流入させてもよい。また、濃縮水の流れ方向も適宜決定される。
【００２３】
次に、本発明の他の実施の形態における脱イオン水製造装置について説明する。すなわち、本実施の形態例は、図１で示される電気式脱イオン水製造装置（以下、「ＥＤＩ−１」とも言う）を有し、該電気式脱イオン水製造装置の２つの小脱塩室を接続する配管途中に逆浸透膜装置（以下、「ＲＯ」とも言う）及び紫外線酸化装置（以下、「ＵＶox」とも言う）のいずれか一方、又は両方共に設置するか、あるいは更に該電気式脱イオン水製造装置の後段に限外濾過膜装置（以下、「ＵＦ」とも言う）又は精密濾過膜装置（以下、「ＭＦ」とも言う）を設置するものである。本実施の形態における電気式脱イオン水製造装置は図１中、貯槽２７及びポンプ２５などを省略して配管１２ａと配管１３ａを直接接続した電気式脱イオン水製造装置（以下、「ＥＤＩ- ２」とも言う）であってもよい。次に、具体的な脱イオン水製造装置例と被処理水の流れを次に示す。
【００２４】
（脱イオン水製造装置Ｉ）
脱イオン水製造装置Ｉは第１ＲＯ及びＥＤＩ- １をこの順序で直列に接続し、ＥＤＩ- １の上流側の小脱塩室と下流側の小脱塩室を連接する配管途中でポンプ２５の下流側に第２ＲＯを設置したものである。第１ＲＯは後段のＥＤＩ- １の負荷を低減するために設置され、第２ＲＯは上流側小脱塩室の処理水中のホウ素や有機物などの不純物イオンを除去するために設置されるもので、双方とも公知の逆浸透膜装置（逆浸透膜モジュール）が使用できる。第１及び第２ＲＯに使用される逆浸透膜としては、特に制限されず、酢酸セルロース系非対称性膜、ポリアミド系複合合成膜などが例示される。また、ＲＯの形態としては、スパイラルモジュール、中空糸モジュール、平膜モジュールなどが例示される。
【００２５】
脱イオン水製造装置Ｉにおいて、第１ＲＯ透過水は先ずＥＤＩ- １の第２小脱塩室（Ａ）に流入する。次いで、この第２小脱塩室の流出水は第２ＲＯに供給され、次いで第２ＲＯ透過水はＥＤＩ- １の第１小脱塩室（Ｋ／Ａ）に流入する。この方法によれば、ＥＤＩ- １の第２小脱塩室（Ａ）でアニオン成分が除去され、この小脱塩室の流出水はアルカリ側となる。このため、被処理水中からの除去が困難とされるホウ素の解離が進むか、あるいは何らかの電気的処理を受けたことによりホウ素の存在形態が変化し、次いで流入する第２ＲＯやＥＤＩ- １の第１小脱塩室（Ｋ／Ａ）で、ホウ素の除去効率が一層高まる。
【００２６】
（脱イオン水製造装置II）
脱イオン水製造装置IIは第１ＲＯ及びＥＤＩ- ２をこの順序で直列に接続し、ＥＤＩ- ２の上流側の小脱塩室と下流側の小脱塩室を連接する配管途中にＵＶoxを設置したものである。すなわち、脱イオン水製造装置Ｉと異なる点は貯槽とポンプを省略し、第２ＲＯに代えてＵＶoxを使用した点にある。ＵＶoxとしては、被処理水に少なくとも１８５nm付近の波長を照射可能な紫外線ランプを備え、被処理水中の有機物を分解可能なものであればよい。ＵＶoxは、通常１８５nm付近の波長の紫外線に加えて、それより有機物分解能力が低い２５４nm付近の波長の紫外線も照射可能な装置である。
【００２７】
脱イオン水製造装置IIにおいて、第１ＲＯの透過水は後段のＥＤＩ- ２の第２小脱塩室（Ａ）に流入する。次いで、この第２小脱塩室の流出水はＵＶoxに供給され、次いでＵＶoxの処理水はＥＤＩ- ２の第１小脱塩室（Ｋ／Ａ）に流入する。この方法によれば、脱イオン水製造装置I の場合と同様、ＥＤＩ- ２の第２小脱塩室（Ａ）でアニオン成分が除去され、該小脱塩室の流出水はアルカリ側となる。このため、被処理水中の有機物の解離が進むか、あるいは何らかの電気的処理を受けたことにより有機物の存在形態が変化し、次いで流入するＵＶoxで酸化し易くなる。また、ＥＤＩ- ２の第２小脱塩室（Ａ）で有機物の一部が除去される。次いで流入するＵＶoxは残存する有機物を酸化するだけでよく酸化効率が向上する。
【００２８】
（脱イオン水製造装置III ）
脱イオン水製造装置III は第１ＲＯ及びＥＤＩ- １をこの順序で直列に接続し、ＥＤＩ- １の上流側の小脱塩室と下流側の小脱塩室を連接する配管途中に第２ＲＯ及びＵＶoxを上流側よりこの順序で直列に設置したものである。すなわち、脱イオン水製造装置Ｉと異なる点は第２ＲＯの後段側でＥＤＩ- １の第１小脱塩室の手前に更にＵＶoxを設置した点にある。
【００２９】
脱イオン水製造装置III において、第１ＲＯ透過水は先ずＥＤＩ- １の第２小脱塩室（Ａ）に流入する。次いで、この第２小脱塩室の流出水は第２ＲＯに供給され、第２ＲＯ透過水はＵＶoxに供給され、次いでＵＶox処理水はＥＤＩ- １の第１小脱塩室（Ｋ／Ａ）に流入する。この方法によれば、前記脱イオン水製造装置I と同様の効果を奏する他、ＵＶoxへの供給水はＲＯの透過水であるため、第２ＲＯで有機物の他の一部が更に除去され、ＵＶoxは残存する有機物の酸化を行うだけでよく更に効率的である。また、ＵＶoxの酸化分解で生じる炭酸ガスも少なくなり後段のＥＤＩ- １の第１小脱塩室（Ｋ／Ａ）での負荷も低減される。
【００３０】
この脱イオン水製造装置III の変形例として、第２ＲＯとＵＶoxの設置順序を入れ換えることもできる。すなわち、ＥＤＩ- １の第２小脱塩室の流出水はＵＶoxに供給され、ＵＶox処理水は第２ＲＯに供給され、次いで第２ＲＯ透過水はＥＤＩ- １の第１小脱塩室（Ｋ／Ａ）に流入する。しかし、前段のＵＶoxで有機物は分解されるものの、分解物の炭酸ガスは第２ＲＯで除去できず、ＥＤＩ- １の第１小脱塩室（Ｋ／Ａ）の負荷となることや、ＵＶoxでは酸が生成し、その処理水はアルカリ側にならないため、第２ＲＯでホウ素などが有効に除去できないなどの理由から、脱イオン水製造装置III の方が好適である。
【００３１】
また、上記脱イオン水製造装置Ｉ〜III の後段に、限外濾過膜装置又は精密濾過膜装置を設置することもできる。すなわち、ＥＤＩ- １やＥＤＩ- ２の第１小脱塩室の流出水を更に限外濾過膜装置又は精密濾過膜装置により処理すれば、脱イオン水中の微粒子を格段に減少させることができる。限外濾過膜装置や精密濾過膜装置は公知のものが使用できる。
【００３２】
（脱イオン水製造装置IV）
脱イオン水製造装置IVは図２に示すように被処理水から脱イオン水を得ると共に、回収系も含めた総合システム５０である。脱イオン水製造装置IV（記号５０）は大きくは、ＥＤＩ- １前段処理部分４２、ＥＤＩ- １処理部分４３、ＥＤＩ- １後段処理部分４４に分かれる。ＥＤＩ- １前段処理部分４２は上流側より、脱炭酸塔３１、ポンプ３２、第１逆浸透膜装置３３を直列に接続してなる。第１逆浸透膜装置３３の濃縮水ラインは更に、貯槽３９、ポンプ４０及び回収逆浸透膜装置４１の順で接続されている。なお、回収逆浸透膜装置４１は独立したタンク３９、ポンプ４０は必ずしも必要ではなく、ポンプ３２により直接運転することもできる。また、回収逆浸透膜装置４１への給水には必要に応じて、酸注入などによるｐＨ調整、スケール発生防止剤又はスケール分散剤などの注入をすることも可能である。この部分４２では被処理水から不純物イオンを粗取りし、後段のＥＤＩ- １の負荷を低減すると共に、第１逆浸透膜装置３３の濃縮水を回収逆浸透膜装置４１で回収して、被処理水に戻している。なお、脱炭酸塔３１は原水中の炭酸などの溶存ガス成分、特に炭酸を除去するために設置されるもので、公知の脱炭酸塔、真空脱気塔が使用できる。
【００３３】
ＥＤＩ- １処理部分４３は、ＥＤＩ- １の上流側小脱塩室（第２小脱塩室）ｄ₂ 、ｄ₄ 、ｄ₆ 、ｄ₈ 、貯槽２７、ポンプ２５、第２逆浸透膜装置３４、紫外線酸化装置３５、膜脱炭酸装置３６、ＥＤＩ- １の下流側小脱塩室（第１小脱塩室）ｄ₁ 、ｄ₃ 、ｄ₅ 、ｄ₇ の順で接続されている。図中、ＥＤＩ- １の上流側小脱塩室（第２小脱塩室）と下流側小脱塩室（第１小脱塩室）は離れて記載されているが、これは作図及び説明の便宜上の簡略表示であり、実際は図１での説明通りである。また、図に示すこれらの小脱塩室から出ている濃縮水はＥＤＩ- １の濃縮室から流出する濃縮水であり同一のものである。これらの濃縮水は第２逆浸透膜装置３４の濃縮水と共に回収され、被処理水に戻される。
【００３４】
このＥＤＩ- １処理部分４３での不純物イオンの除去作用などは前述の通りであるが、ここでは更に紫外線酸化装置３５の後段に膜脱炭酸装置３６を設置し、紫外線酸化で生じた被処理水中の炭酸ガスを除去している。なお、膜脱炭酸装置３６は、公知の膜脱炭酸装置が使用できる。また、膜脱炭酸装置３６で使用される脱気膜は疎水性の材質からなる多孔膜又は非多孔膜であり、気体は透過するが液体は透過しない特性を有するものである。脱気膜の材質としては、ポリプロピレン、ポリエチレン、ポリメチルペンテン、シリコン樹脂、フッ素樹脂などからなる多孔膜又は非多孔膜が挙げられる。なお、この場合、膜脱炭酸装置の代わりに脱炭酸塔を使用することもできるが、処理水の水質を維持するためには膜脱炭酸装置が好ましい。すなわち、膜脱炭酸装置は被処理水を通水する膜の反対側を減圧して脱気するので、装置内で被処理水は汚染されにくく、逆浸透膜の透過水の脱気に好都合である。一方、脱炭酸塔は空気を被処理水に吹き込むので、空気中の汚染物質が被処理水に移行する可能性があり、逆浸透膜の透過水に利用するのは得策ではない。
【００３５】
ＥＤＩ- １後段処理部分４４は、限外濾過装置３８及び脱イオン水が使用点（ユースポイント）で使用された使用水を回収する回収システム３８からなる。限外濾過装置３７ではＥＤＩの処理水から微粒子を除去する一方、濃縮水を被処理水に戻し、水の回収率を向上させている。また、回収システム３８で回収された回収水も被処理水に戻している。
【００３６】
【実施例】
次に、実施例を挙げて本発明を更に具体的に説明するが、これは単に例示であって、本発明を制限するものではない。
実験例１
図１に示す電気式脱イオン水製造装置の第１小脱塩室の圧力及び第２小脱塩室の圧力が処理水の水質に与える影響を検討した。すなわち、下記装置仕様及び運転条件下において、図１に示すのと同様の構成で３個の脱イオンモジュール（６個の小脱塩室）を並設して構成される電気式脱イオン水製造装置の脱塩室及び濃縮室にそれぞれ通水し、運転開始１０分後の定常運転後、第２小脱塩室（上流側）の入口圧力Ｐ１及び出口圧力Ｐ２、第１小脱塩室（下流側）の入口圧力Ｐ３及び出口圧力Ｐ４をポンプ２５及びバルブ２１、２２で操作しながら表１に示すように変化させ、その後、処理水を採取してその水質を調べた。結果を表１に示す。なお、No.（実験番号）１〜８までは被処理水の供給圧力（Ｐ１）を０．１５MPa （ゲージ圧）とし、No.（実験番号）９〜１１までは被処理水の供給圧力（Ｐ１）を０．２５MPa （ゲージ圧）とした。水質の単位はＭΩ-cm であり、圧力単位は１０^-1MPa(ゲージ圧) である。
【００３７】
・被処理水及び濃縮水；工業用水を逆浸透膜装置で処理して得た透過水
・被処理水の抵抗率；０．３１ＭΩ- ｃｍ
・第１小脱塩室；幅３００mm、高さ６００mm、厚さ３mm
・第１小脱塩室充填イオン交換樹脂；アニオン交換樹脂（Ａ）とカチオン交換樹脂（Ｋ）との混合イオン交換樹脂（混合比は体積比でＡ：Ｋ＝１：１）
・第２小脱塩室；幅３００mm、高さ６００mm、厚さ８mm
・第２小脱塩室充填イオン交換樹脂；アニオン交換樹脂
・装置全体の流量；１ｍ³ ／ｈ．
【００３８】
【表１】

【００３９】
表１から明らかなように、実験番号４〜７及び１０、１１のＰ３≧Ｐ１及びＰ４≧Ｐ２となる関係の時に、処理水の水質低下が認められない。すなわち、第１小脱塩室（下流側）の全体圧力が第２小脱塩室（上流側）の全体圧力より高い場合に安定した水質が得られている。このことは、第２小脱塩室と第１小脱塩室が隣接し、しかも第２小脱塩室の流出水が第１小脱塩室へ供給される構造から、実験番号１や８のように第２小脱塩室の圧力が第１小脱塩室の圧力より大きい時、第２小脱塩室から第１小脱塩室へイオンや液の漏洩が起こり、この漏洩が水質の低下をもたらしたものと推定される。
【００４０】
実験例２
実験例１における実験番号５で運転を継続し、１２０日間の処理水中の有機物含有量（μg-ｃ/L) 、ホウ素含有量( μg/L)及び微粒子数の変動を調べた。結果を図３に示す。なお、１２０日間後の処理水の水質は１７．５ＭΩ-cm を維持していた。微粒子数は１ｍｌ当たりの粒子径０．０７μm 以上の粒子数（×１０⁴ ）で示す。
【００４１】
図３より、処理水の水質の低下は認められないものの、有機物含有量、ホウ素含有量及び微粒子数は変動しており、除去は不十分であった。
【００４２】
実験例３
実験例１における実験番号５の運転を継続し、４０日間の処理水中のホウ素含有量( μg/L)の変動を調べた。結果を図４に示す。なお、図１中、実験番号５の条件に更に、第２小脱塩室の流出ラインと第１小脱塩室の流入ラインを接続する配管１３ａ途中に逆浸透膜装置を設置したもの（実験番号１２）及び実験番号５の条件に被処理流入ライン１１に逆浸透膜装置を設置したもの（実験番号１３）も同様の実験を行った。実験番号１２は前述の「脱イオン水製造装置Ｉ」に相当し、実験番号１３は従来のいわゆる前処理用逆浸透膜装置の複数段（２段）設置に相当する。結果を図４に示す。
【００４３】
図４より、電気式脱イオン水製造装置の前段に逆浸透膜装置を設置した場合は、ホウ素の除去効果はほとんどなかったのに対して、本実施の形態例である実験番号１２はホウ素の除去が格段に優れるものであった。
【００４４】
実験例４
実験例１における実験番号５で運転を継続し、４０日間の処理水中の有機物含有量( μg/L)の変動を調べた。結果を図５に示す。なお、図１中、実験番号５の条件に更に、第２小脱塩室の流出ラインと第１小脱塩室の流入ラインを接続する配管１３ａ途中に紫外線酸化装置を設置したもの（実験番号１４）及び実験番号５の条件に被処理流入ライン１１に紫外線酸化装置を設置したもの（実験番号１５）も同様の実験を行った。実験番号１４は前述の「脱イオン水製造装置II」に相当する。結果を図５に示す。
【００４５】
図５より、電気式脱イオン水製造装置の前段に紫外線酸化装置を設置した場合（実験番号１５）は、有機物の除去効果はあったものの、本実施の形態例である実験番号１４に比較すると劣るものであった。
【００４６】
実験例５
実験例３における実験番号１２において、逆浸透膜装置の下流側で第１小脱塩室の手前に紫外線酸化装置を設置して運転を行い、４０日間の処理水中の有機物含有量( μg-c/L)、ホウ素含有量（μg/L)及び微粒子数（個）の変動を調べた（実験番号１６）。また、この逆浸透膜装置と紫外線酸化装置の位置を入れ換えた場合も同様の実験を行った（実験番号１７）。なお、実験番号１６は前述の「脱イオン水製造装置III 」に、実験番号１７は前述の「脱イオン水製造装置III の変形例」にそれぞれ相当する。結果を図６に示す。また、微粒子数（個）の変動は実験番号１６についてのみ行い、この結果は図７に示す。
【００４７】
図６より、実験番号１６では紫外線酸化装置への供給水は逆浸透膜装置の透過水であるため、逆浸透膜装置で有機物の一部が除去され、紫外線酸化装置は残存する有機物の酸化を行うだけでよく有機物の除去効果は極めて高い。また、逆浸透膜装置の被処理水はアルカリであるため、ホウ素が解離し易く、逆浸透膜装置で十分に除去されている。一方、実験番号１７では紫外線酸化装置で酸が生じ、逆浸透膜装置の被処理水はアルカリではないため、ホウ素成分は逆浸透膜装置で十分には除去されていない。
【００４８】
実験例６
実験例５における実験番号１６の電気式脱イオン水製造装置の後段に限外濾過膜装置を設置して運転を行い、４０日間の処理水中の微粒子数の変動を調べた（実験番号１８）。結果を図７に示す。微粒子数は１ｍｌ中の粒子径０．０７μm 以上の微粒子の粒子数で示す。
【００４９】
図７より、電気式脱イオン水製造装置の後段に限外濾過膜装置を設置することにより、脱イオン水中の微粒子数は格段に減少する。
【００５０】
【発明の効果】
本発明（１）によれば、電気式脱イオン水製造装置ではイオン交換体が充填された脱塩室１つ当たりの濃縮室の数を従来の約半分にすることができ、電気抵抗を著しく低減できる。また、２つの小脱塩室のうち、少なくとも１つの脱塩室に充填されるイオン交換体を例えばアニオン交換体のみ、又はカチオン交換体のみ等の単一イオン交換体もしくはアニオン交換体とカチオン交換体の混合イオン交換体とすることができ、イオン交換体が充填された脱塩室の厚さを電気抵抗を低減し、且つ高い電流効率を得る最適な厚さに設定することができる。また、運転当初、処理水の使用量が増大して被処理水の供給量が増え上流側の小脱塩室内の圧力が上昇しても下流側の小脱塩室内圧力を上流側の小脱塩室内圧力より常に高めることができ、上流側小脱塩室から下流側小脱塩室へのイオンの移動や液の漏洩などが防止でき、高純度の水質をより安定して得ることができる。
【００５１】
本発明（２）によれば、一方の小脱塩室に充填されるイオン交換体を、アニオン交換体とし、他方の小脱塩室に充填されるイオン交換体を、カチオン交換体とアニオン交換体の混合体とした場合、一方（上流側）の小脱塩室でアニオン成分が除去され、この小脱塩室の流出水はアルカリ側となる。このため、被処理水中のホウ素や有機物の解離が進むか、あるいは何らかの電気的処理を受けたことによりホウ素や有機物の存在形態が変化し、次いで流入する逆浸透膜装置でホウ素の除去効率が一層高まるか、あるいはＵＶoxで有機物が酸化され易くなる。また、電気式脱イオン水製造装置の第２小脱塩室で有機物の一部が除去され、次いで流入するＵＶoxでは残存する有機物を酸化すればよいから除去効率が向上する。従って、渇水などの自然現象や工場の生産工程からの不純物混入など被処理水の水質が悪化しても対応可能となる。
【００５２】
本発明（３）によれば、逆浸透膜装置や電気式脱イオン水製造装置で除去することができない被処理水中の微粒子を除去することができる。
本発明（４）によれば、アニオン成分を多く含む被処理水、特にシリカ、炭酸等の弱酸性成分を多く含む被処理水を十分に処理することが可能となると共に、２つの小脱塩室を接続する配管途中に逆浸透膜装置や紫外線酸化装置を設置すれば、被処理水中のホウ素や有機酸を効率的に除去できる。
【図面の簡単な説明】
【図１】本発明で使用する電気式脱イオン水製造装置の１例を示す模式図である。
【図２】本発明の実施の形態における脱イオン水製造装置を示すブロック図である。
【図３】実験番号５における運転日数と有機物含有量などの関係を示す図である。
【図４】実験例３で得られる運転日数とホウ素含有量の関係を示す図である。
【図５】実験例４で得られる運転日数と有機物含有量の関係を示す図である。
【図６】実験例５で得られる運転日数と有機物含有量等の関係を示す図である。
【図７】実験例５及び実験例６で得られる運転日数と微粒子数の関係を示す図である。
【図８】従来の電気式脱イオン水製造装置の模式図である。
【符号の説明】
Ｄ、Ｄ₁ 〜Ｄ₄ 、１０４ 脱塩室
ｄ₁ 、ｄ₃ 、ｄ₅ 、ｄ₇ 、 第１小脱塩室
ｄ₂ 、ｄ₄ 、ｄ₆ 、ｄ₈ 、 第２小脱塩室
１、１０５ 濃縮室
２、１１２、１１３ 電極室
３、１０１ カチオン膜
４、１０２ アニオン膜
５ 中間イオン交換膜
６、１０９ 陰極
７、１１０ 陽極
８、１０３ イオン交換体
１０、１００ 電気式脱イオン水製造装置
１１、１１１ 被処理水流入ライン
１２ 第２小脱塩室の処理水流出ライン
１３ 第１小脱塩室の被処理水流入ライン
１４、１１４ 脱イオン水流出ライン
１５、１１５ 濃縮水流入ライン
１６、１１６ 濃縮水流出ライン
１７、１１７ 電極水流入ライン
１８、１１８ 電極水流出ライン
２１、２２ バルブ
２３、２４、２６ 配管
２５、３２、４０ ポンプ
２７、３９ 貯槽
３１ 脱炭酸塔
３３ 第１逆浸透膜装置
３４ 第２逆浸透膜装置
３５ 紫外線酸化装置
３６ 膜脱炭酸装置
３７ 限外濾過膜装置
３８ 回収システム
４１ 回収逆浸透膜装置[0001]
BACKGROUND OF THE INVENTION
The present invention is used in various industries or laboratory facilities such as semiconductor manufacturing field, medical and pharmaceutical manufacturing field, power generation field such as nuclear power and thermal power, food industry, etc., and is a power saving type capable of supplying high-purity water quality more stably. The present invention relates to a deionized water production apparatus having an electric deionized water production apparatus.
[0002]
[Prior art]
As a method for producing deionized water, there is conventionally known a method in which deionized water is passed through an ion exchange resin to be treated. In this method, regeneration is performed with a drug when the ion exchange resin is saturated with ions. In order to eliminate such disadvantages in processing operations, recently, a method for producing deionized water by an electric deionization method which does not require any regeneration by a chemical agent has been established and has been put into practical use.
[0003]
FIG. 8 shows a schematic sectional view of the conventional typical electric deionized water production apparatus. As shown in FIG. 8, the cation exchange membrane 101 and the anion exchange membrane 102 are alternately arranged apart from each other, and every other ion exchanger 103 is placed in the space formed by the cation exchange membrane 101 and the anion exchange membrane 102. Fill with desalination chamber. The treated water inflow side (front stage) of the desalting chamber is filled with anion exchange resin 103a, and the treated water outflow side (rear stage) of the desalting chamber is filled with a mixed ion exchange resin 103b of a cation exchange resin and an anion exchange resin. Filled. Further, a portion not filled with the ion exchanger 103 formed by the anion exchange membrane 102 and the cation exchange membrane 101 located adjacent to each of the desalting chambers 104 is a concentration chamber 105 for flowing concentrated water.
[0004]
In addition, a cathode 109 is disposed on one side of the desalination chamber, and an anode 110 is disposed on the other end side. In addition, the position where the above-mentioned spacer is sandwiched is the concentrating chamber 105, and on both outer sides of the concentrating chamber 105 at both ends, if necessary, a partition such as a cation exchange membrane 101, an anion exchange membrane 102, or a simple membrane having no ion exchange properties. The portions where the membranes are arranged and the electrodes 109 and 110 that are partitioned by the partition membrane are in contact with each other are referred to as a cathode chamber 112 and an anode chamber 113, respectively. Thus, in the conventional electric deionized water production apparatus, the number of concentrating chambers is one more than the number of demineralizing chambers, or the concentrating chambers are provided at both ends without partition membranes and the electrode chambers. In that case, it was one less.
[0005]
The case where deionized water is manufactured by such an electric deionized water manufacturing apparatus will be described with reference to FIG. That is, a direct current is passed between the cathode 109 and the anode 110, water to be treated flows from the water to be treated inflow line 111, concentrated water from the concentrated water inflow line 115, and electrode water inflow lines 117 and 117. Electrode water flows from each. To-be-treated water flowing from the to-be-treated water inflow line 111 flows down the desalting chamber 104, and first, when passing through the anion exchange resin 103a in the previous stage, anion components such as hydrochloric acid ions and sulfate ions are removed, When passing through the mixed ion exchange resin 103b of the latter cation exchange resin and anion exchange resin, cation components such as magnesium and calcium are removed. Concentrated water flowing in from the concentrated water inflow line 115 rises in each concentration chamber 105, receives impurity ions moving through the cation exchange membrane 101 and the anion exchange membrane 102, and concentrates as concentrated water in which impurity ions are concentrated. The electrode water flowing out from the outflow line 116 and further flowing in from the electrode water inflow lines 117 and 117 flows out from the electrode water outflow lines 118 and 118. Accordingly, demineralized water is obtained from the deionized water outflow line 114.
[0006]
Various attempts have been made to reduce the electrical resistance of the electrical deionized water production apparatus in order to remove the impurity ions in the water to be treated with power saving using such an electrical deionized water production apparatus. In this case, in the desalting chamber, since the filling method of the ion exchanger used in the desalting chamber and the quality of the treated water required are determined, the electric resistance of the desalting chamber can be reduced. There is a limit. Therefore, measures are often taken to reduce the electrical resistance of the concentrating chamber. For example, Japanese Patent Laid-Open No. 9-24374 discloses a method of reducing the electrical resistance in the concentration chamber by adding and supplying an electrolyte to the concentration chamber. A number of methods have also been reported for promoting the increase in conductivity by circulating concentrated water and reducing the electrical resistance of the concentration chamber.
[0007]
[Problems to be solved by the invention]
However, the method of reducing the electrical resistance of the concentrating chamber by adding and supplying the electrolyte to the concentrating chamber requires installation of a pump, a drug storage tank, a supply pipe, and the like for supplying the electrolyte to the concentrating chamber. Increase in installation cost and installation cost, and it is necessary to regularly replenish and manage medicines. In addition, the method of accelerating the increase in conductivity by circulating the concentrated water and reducing the electrical resistance of the concentrating chamber also increases the hardness components such as calcium and magnesium contained in the concentrated water and promotes the generation of scale. In particular, there is a problem of increasing the electrical resistance.
[0008]
On the other hand, industrial water, tap water, recovered water from a production process using deionized water or the like is used alone or in combination as water to be treated in an electrical deionized water production apparatus. Industrial water and tap water have water quality fluctuations due to the season and weather. In particular, drought and rainfall will cause water quality fluctuations. The recovered water from the production process is treated as activated water, ion exchange, reverse osmosis membrane equipment, etc., and then used as water to be treated. There are fluctuations in water quality. In this case, it may be possible to strengthen the pretreatment of activated carbon, ion exchange, reverse osmosis membrane device, etc. in the front stage of the electric deionized water production device, but only reinforcement at the same position (pretreatment) Then, it cannot respond to the above water quality fluctuation | variations, and cannot suppress stably the water quality fall of the treated water of an electrical deionized water manufacturing apparatus. In addition, at the beginning of operation, the amount of treated water increases rapidly, and a large amount of treated water may flow into the desalination chamber. Even in such a case, the quality of the treated water should be reduced. However, it is necessary to stably supply treated water having high-purity water quality.
[0009]
Therefore, the object of the present invention is to reduce electrical resistance by drastic improvement from the structural aspect of the electric deionized water production apparatus without adding chemicals to the concentrated water, and to increase the supply amount of water to be treated. An object of the present invention is to provide a deionized water production apparatus using a power-saving electric deionized water production apparatus that can cope with the deterioration of the quality of water to be treated and can supply high-purity water quality more stably.
[0010]
[Means for Solving the Problems]
In this situation, as a result of intensive studies, the present inventors have (1) a conventional desalination chamber structure in which a cation exchange membrane is sealed on one side of a frame and an anion exchange membrane is sealed on the other side. The cation exchange membrane further comprises an intermediate ion exchange membrane that divides the desalting chamber into two parts between the cation exchange membrane and the anion exchange membrane, thereby providing a desalting chamber having two small desalting chambers adjacent to each other. Concentration chambers are provided on both sides of the desalting chamber via a membrane and an anion exchange membrane, and these desalting chambers and concentrating chambers are arranged between the anode and the cathode, and the water to be treated is drained on one side while applying voltage. The deionized water is produced by flowing into the salt chamber and allowing the effluent from the small demineralization chamber to flow into the other small desalination chamber and removing the impurity ions in the water to be treated by flowing the concentrated water into the concentration chamber. If so, the number of concentration chambers per desalting chamber filled with ion exchangers The electrical resistance of the electric deionized water production apparatus can be reduced to about half that of the conventional one, and (2) in the middle of piping connecting two small demineralization chambers of such an electric deionized water production apparatus If a pressure pump is installed in the pump and the pressure of the inflow water to the downstream small desalination chamber is increased, the downstream small desalination chamber pressure can always be higher than the upstream small desalination chamber pressure. It is possible to prevent ions from moving from the upstream small desalination chamber to the downstream small desalination chamber or leakage of liquid even if the pressure in the upstream small desalination chamber rises with an increase in the amount of water to be treated (3) Moreover, if a reverse osmosis membrane device, an ultraviolet oxidizer, etc. are installed in the middle of the piping connecting the two small demineralization chambers of such an electric deionized water production device, removal from the water to be treated is possible. Boron and organic matter (TOC), which are considered difficult, can be removed very efficiently. Found etc., it has led to the completion of the present invention.
[0011]
That is, the invention (1) of claim 1 is divided into two cation exchange membranes, one anion exchange membrane on the other side, and two intermediate ion exchange membranes located between the cation exchange membrane and the anion exchange membrane. A small desalting chamber is filled with an ion exchanger to form a desalting chamber, and concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane. It is formed between an anode and a cathode, and the outflow pipe of the one small desalination chamber is connected to the inflow pipe of the other small desalination chamber, and a pump is provided in the middle of the pipe connecting the two small desalination chambers. The present invention provides a deionized water production apparatus characterized by having an electrical deionized water production apparatus in which is installed. By adopting such a configuration, in the electric deionized water production apparatus, the number of concentration chambers per demineralization chamber filled with an ion exchanger can be reduced to about half of the conventional one, and the electrical resistance can be significantly reduced. . In addition, the ion exchanger filled in at least one of the two small desalting chambers is a cation exchange with a single ion exchanger or an anion exchanger such as only an anion exchanger or only a cation exchanger. The thickness of the desalting chamber filled with the ion exchanger can be set to an optimum thickness for reducing electric resistance and obtaining high current efficiency. In addition, even if the amount of treated water increases at the beginning of operation and the pressure in the upstream small desalination chamber rises due to an increase in the supply amount or blockage of treated water, the pressure in the downstream small desalination chamber increases. The pressure can always be higher than the pressure in the small desalination chamber on the side, and ion migration from the upstream small desalination chamber to the downstream small desalination chamber, leakage of liquid, etc. can be prevented, resulting in more stable high-purity water quality. Can supply. Furthermore, the flow rate of the downstream small desalting chamber can be made larger than that of the upstream small desalting chamber. For example, when the water after use at the point of use (use point) can be recovered with sufficient quality and simple processing, or when it is circulated and recovered without being used at the point of use, these recovered water can be Without passing through the small desalting chamber, it can be supplied directly to the downstream small desalting chamber.
[0012]
The invention (2) of claim 2 is characterized in that the cation exchange membrane on one side, the anion exchange membrane on the other side, and two small detachments partitioned by the intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane. A salt chamber is filled with an ion exchanger to form a desalting chamber, and concentration chambers are provided on both sides of the desalting chamber via the cation exchange membrane and anion exchange membrane, and these desalting chamber and concentration chamber are used as an anode. A reverse osmosis membrane formed between the cathodes, the outflow pipe of the one small desalination chamber being connected to the inflow pipe of the other small desalination chamber, and in the middle of the pipe connecting the two small desalination chambers The present invention provides a deionized water production apparatus having an electrical deionized water production apparatus in which at least one selected from an apparatus, an ultraviolet oxidation apparatus, and a degassing membrane apparatus is installed. By adopting such a configuration, an ion exchanger filled in one small desalting chamber partitioned by the intermediate ion exchange membrane and the other side anion exchange membrane is an anion exchanger, and the one side cation exchange is performed. When the ion exchanger filled in the other small desalting chamber partitioned by the membrane and the intermediate ion exchange membrane is a mixture of a cation exchanger and an anion exchanger, the upstream (one) small desalting chamber Thus, the anion component is removed, and the outflow water of the small desalting chamber is on the alkali side. For this reason, with regard to boron, boron dissociation proceeds in the water to be treated, or the presence form of boron changes due to some electrical treatment, and the reverse osmosis membrane device that flows in further improves the boron removal efficiency. Rise. Similarly, regarding the organic matter, dissociation of the organic matter in the water to be treated proceeds, or the presence of the organic matter changes due to some electrical treatment, and then it becomes easy to be oxidized by the incoming UVox. In addition, since a part of the organic matter is removed in the second small desalting chamber of the electric deionized water production apparatus, the remaining organic matter may be oxidized in the next incoming UVox, and the removal efficiency is improved. Therefore, it is possible to cope with the deterioration of the quality of the water to be treated, such as natural phenomena such as drought, and impurities from the production process of the factory.
[0013]
The invention (3) of claim 3 is that an ultrafiltration membrane device or a microfiltration membrane device is installed at a subsequent stage of the electric deionized water production device, and fine particles in treated water of the electric deionized water production device are collected. Further, the present invention provides the deionized water production apparatus according to (1) or (2) above, which is further removed. By adopting such a configuration, it is possible to remove the fine particles in the water to be treated that cannot be removed by the reverse osmosis membrane device or the electric deionized water production device, in addition to the same effects as the above invention.
[0014]
In the invention (4) of claim 4, the ion exchanger filled in one small desalting chamber partitioned by the intermediate ion exchange membrane and the other side anion exchange membrane is an anion exchanger, The ion exchanger filled in the other small desalting chamber partitioned by the cation exchange membrane on the side and the intermediate ion exchange membrane is a mixture of a cation exchanger and an anion exchanger (1) ) Or (2) deionized water production apparatus. By adopting such a configuration, it becomes possible to sufficiently treat water to be treated containing a large amount of anionic components, particularly water to be treated containing a large amount of weakly acidic components such as silica and carbonic acid, and two small desalting chambers. If a reverse osmosis membrane device or an ultraviolet oxidation device is installed in the connecting pipe, boron and organic acid in the water to be treated can be efficiently removed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
One example of the electrical deionized water production apparatus used in the present invention will be described with reference to FIG. FIG. 1 is a schematic view of the electric deionized water production apparatus. As shown in FIG. 1, the cation exchange membrane 3, the intermediate ion exchange membrane 5 and the anion exchange membrane 4 are alternately arranged apart from each other, and ion exchange is performed in the space formed by the cation exchange membrane 3 and the intermediate ion exchange membrane 5. The first small desalination chamber d filled with the body 8 ₁ , D _Three , D _Five , D ₇ And a space formed by the intermediate ion exchange membrane 5 and the anion exchange membrane 4 is filled with an ion exchanger 8 to form a second small desalting chamber d. ₂ , D _Four , D ₆ , D ₈ Forming a first small desalting chamber d ₁ And the second small desalination chamber d ₂ Desalination chamber D ₁ , First small desalination chamber d _Three And the second small desalination chamber d _Four Desalination chamber D ₂ , First small desalination chamber d _Five And the second small desalination chamber d ₆ Desalination chamber D _Three , First small desalination chamber d ₇ And the second small desalination chamber d ₈ Desalination chamber D _Four And Desalination chamber D ₂ , D _Three A portion not filled with the ion exchanger 8 formed by the anion exchange membrane 4 and the cation exchange membrane 3 located next to each other is defined as a concentration chamber 1 for flowing concentrated water. Desalination chamber D from the left side of the figure ₁ , Concentration chamber 1, Desalination chamber D ₂ , Concentration chamber 1, Desalination chamber D _Three , Concentration chamber 1, Desalination chamber D _Four Form. Further, in the two small desalination chambers adjacent via the intermediate membrane, the treated water outflow line 12 of the second small desalination chamber is connected to the storage tank 21 through the collecting pipe 12a, and the pump 25 extended from the storage tank 27 is connected. The outflow pipe 23 having the valve 21 is connected to the treated water inflow line 13 of the first small desalination chamber through the pipe 13a. In addition, a return pipe 24 having a valve 22 of an outflow pipe 23 and a nitrogen gas pipe 26 are connected to the storage tank 27. Symbol P1 is a pressure gauge for measuring the inlet pressure of the second small desalting chamber (upstream side small desalting chamber), P2 is a pressure gauge for measuring the outlet pressure of the second small desalting chamber, and P3 is the first small desalting chamber. P4 indicates a pressure gauge for measuring the inlet pressure of the desalting chamber (downstream small desalting chamber), and P4 indicates a pressure gauge for measuring the outlet pressure of the first small desalting chamber.
[0016]
The demineralization chamber as described above is composed of a deionization module formed by two inner frames and three ion exchange membranes. That is, although not shown in the figure, a cation exchange membrane is sealed on one side of the first frame, an ion exchanger is filled in the hollowed portion of the first frame, and then the other of the first frame is filled. An intermediate ion exchange membrane is sealed to the part to form a first small desalting chamber. Next, the second frame is sealed so as to sandwich the intermediate ion exchange membrane, and the hollowed portion of the second frame is filled with the ion exchanger, and then the other portion of the second frame is filled with the anion exchange membrane. To form a second small desalting chamber. The ion exchange membrane is relatively soft, and when the first frame and the second frame are filled with the ion exchanger and sealed on both sides with the ion exchange membrane, the ion exchange membrane is curved. In order to prevent the packed bed of the ion exchanger from becoming uneven, a plurality of ribs are provided vertically in the space portion of the first frame body and the second frame body. Although not shown in the figure, the inlet of the treated water or the outlet of the treated water is provided at the upper part of the first frame and the second frame, and the outlet or the treated water is provided at the lower part of the frame. A water inlet is attached. FIG. 1 shows a state in which a plurality of such deionization modules are arranged in parallel with a spacer not shown in the figure interposed therebetween, and a cathode 6 is arranged on one side of the deionization modules arranged side by side. And an anode 7 is disposed on the other end side. In addition, the position where the above-mentioned spacer is sandwiched is the concentration chamber 1, and a partition membrane such as a cation exchange membrane, an anion exchange membrane, or a simple membrane having no ion exchange properties on both outer sides of the desalting chamber D at both ends as necessary. The portions where the electrodes 6 and 7 that are partitioned by the partition film are in contact with each other may be electrode chambers 2 and 2, respectively.
[0017]
When producing deionized water by such an electric deionized water production apparatus, the following operation is performed. That is, the DC water is passed between the cathode 6 and the anode 7, the water to be treated flows from the water to be treated inflow line 11, the concentrated water flows from the concentrated water inflow line 15, and from the electrode water inflow lines 17 and 17. Electrode water flows in each. The treated water flowing from the treated water inflow line 11 is the second small desalination chamber d. ₂ , D _Four , D ₆ , D ₈ For example, impurity ions are removed when passing through the packed bed of the anion exchanger 81. Furthermore, the effluent water that has passed through the treated water effluent line 12 of the second small desalination chamber flows into the storage tank 27. And it stores in the state which blocked | interrupted mixing of external gas, especially the carbon dioxide gas in air by a nitrogen seal. Here, the nitrogen source used for sealing the tank can be nitrogen in a gas cylinder, liquid nitrogen, a gas separation membrane, reformed air from which carbon dioxide gas has been removed from the air by a pressure swing adsorption method, or nitrogen gas from which oxygen has been removed. The stored outflow water is boosted by the pump 25, and then passes through the treated water inflow line 13 of the first small desalination chamber to the first small desalination chamber d. ₁ , D _Three , D _Five , D ₇ Here, for example, impurity ions are removed when passing through a packed bed of a mixed ion exchanger 82 of a cation exchanger and an anion exchanger, and deionized water is obtained from the deionized water outflow line 14. Concentrated water flowing in from the concentrated water inflow line 15 rises in each concentration chamber 1, receives impurity ions moving through the cation exchange membrane 3 and the anion exchange membrane 4, and concentrates the impurity ions as concentrated water. The electrode water flowing out from the concentrated water outflow line 16 and further flowing in from the electrode water inflow lines 17, 17 flows out from the electrode water outflow lines 18, 18. In this case, the supply pressure of the pump 25 and the opening degrees of the valves 21 and 22 are determined so as to satisfy both the pressure of P3 ≧ P1 and the pressure of P4 ≧ P2. By the above operation, the impurity ions in the water to be treated are electrically removed, and the use amount of the treated water, in particular, the second small desalting chamber pressure (P1) is increased as the large amount of water to be treated is supplied. Even if it rises, the pressure in the first small desalination chamber can always be higher than the pressure in the second small desalination chamber, so that ions move from the second small desalination chamber to the first small desalination chamber, liquid leaks, etc. Can be prevented. The pressure difference between P3 and P1 and the pressure difference between P4 and P2 is 0.15 MPa (1.5 kg / cm ² (Gauge pressure) It is preferable to set it below. On the contrary, if this pressure difference is too large, liquid leakage from the first small desalting chamber to the second small desalting chamber tends to occur, and the deformation of the ion exchange membrane increases.
[0018]
In FIG. 1, for example, when the storage tank 27 and the pump 25 are omitted, the pipe 12a and the pipe 13a are directly connected, and the outflow water of the second small desalination chamber is directly used as the inflow water of the first small desalination chamber. When the flow rate of the second small desalting chamber increases and the pressure of the second small desalting chamber increases, the second small desalting chamber and the first small desalting chamber are adjacent to each other, and the effluent of the second small desalting chamber is the first small desalting chamber. Due to the structure of supplying directly to the salt chamber, the pressure in the second small desalination chamber is always greater than that in the first small desalination chamber, and ions and liquids are transferred from the second small desalination chamber to the first small desalination chamber. Leakage may occur. In addition, when such a leak occurs, the impurity concentration in the small desalting chamber is always higher in the second small desalting chamber than in the first small desalting chamber, so that the effluent (dewatering) There is a problem that the water quality of (ion water) is deteriorated. However, as shown in FIG. 1, if a booster pump is installed in the middle of a pipe connecting two small desalination chambers and the pressures of P1 to P4 are operated so as to satisfy the above relationship, the amount of water to be treated is supplied. The above problems associated with the increase can be solved. Further, in FIG. 1, the storage tank 27 may be connected to an inflow pipe from another system not shown in the figure. As a result, for example, when the water after use at the point of use can be recovered with a simple process with sufficient water quality, or when it is circulated and recovered without being used at the point of use, the recovered water can be collected from the upstream side. Without passing through the desalting chamber, it can be directly supplied to the small desalting chamber on the downstream side.
[0019]
In this embodiment, the intermediate ion exchange membrane may be either a single membrane of a cation exchange membrane or an anion exchange membrane, or a dual membrane in which both an anion exchange membrane and a cation exchange membrane are arranged. Good. In the case of a dual membrane comprising an anion exchange membrane or a cation exchange membrane in the upper part or lower part of the device, the height (area) of each of the anion exchange membrane and the cation membrane is appropriately determined depending on the quality of the water to be treated or the purpose of treatment. . Moreover, when using a single membrane, an ion exchange membrane is determined according to the ion species to be removed from the water to be treated.
[0020]
The thickness of the first small desalting chamber or the second small desalting chamber is not particularly limited, and is optimal depending on the type and filling method of the ion exchanger filled in the first small desalting chamber or the second small desalting chamber. The thickness should be determined. Therefore, the thickness of the first small desalting chamber may be 3 mm, the thickness of the second small desalting chamber may be 6 mm, and the total thickness, that is, the thickness of the desalting chamber may be 9 mm. In this way, a plurality of desalting chambers and concentration chambers are alternately arranged, and the thickness of the desalting chamber partitioned by the cation exchange membrane and the anion exchange membrane disposed on both sides of the desalting chamber is larger than the conventional one. The thickness can be increased, and is appropriately determined within a range of 1.5 to 18 mm, preferably 6.5 to 15 mm, and more preferably 9 to 13 mm.
[0021]
Further, the ion exchanger filled in the desalting chamber is not particularly limited, and an anion exchanger (hereinafter also referred to as “A”) single bed, a cation exchanger (hereinafter also referred to as “K”) single bed, and Examples include a mixed bed of anion exchanger and cation exchanger (hereinafter also referred to as “K / A”) or a combination thereof. The ion exchanger may be any substance having an ion exchange function, such as an ion exchange resin or an ion exchange fiber, or may be a combination thereof.
[0022]
Moreover, the flow direction in the 1st small desalination chamber and 2nd small desalination chamber of to-be-processed water is not restrict | limited in particular, 1st small desalination chamber and 2nd small desalination other than the said embodiment. The flow direction in the chamber may be different. In addition to the above embodiment, the small desalination chamber into which the water to be treated flows first flows the water to be treated into the first desalting chamber and flows down, and then the effluent from the first desalting chamber is discharged. You may make it flow into a 2nd desalination chamber. Further, the flow direction of the concentrated water is also appropriately determined.
[0023]
Next, a deionized water production apparatus according to another embodiment of the present invention will be described. That is, this embodiment has the electric deionized water production apparatus (hereinafter also referred to as “EDI-1”) shown in FIG. 1, and two small demineralizations of the electric deionized water production apparatus. Either or both of a reverse osmosis membrane device (hereinafter also referred to as “RO”) and an ultraviolet oxidation device (hereinafter also referred to as “UVox”) or both of them are installed in the middle of piping connecting the chambers. An ultrafiltration membrane device (hereinafter also referred to as “UF”) or a microfiltration membrane device (hereinafter also referred to as “MF”) is installed at the subsequent stage of the deionized water production apparatus. The electric deionized water production apparatus in the present embodiment is an electric deionized water production apparatus (hereinafter referred to as “EDI-2”) in which the storage tank 27 and the pump 25 are omitted in FIG. 1 and the pipe 12a and the pipe 13a are directly connected. May also be referred to). Next, a specific example of deionized water production apparatus and the flow of treated water are shown below.
[0024]
(Deionized water production equipment I)
In the deionized water production apparatus I, the first RO and EDI-1 are connected in series in this order, and the pump 25 is connected in the middle of the piping connecting the upstream small desalination chamber and the downstream small desalination chamber of EDI-1. A second RO is installed on the downstream side. The first RO is installed to reduce the load of EDI-1 in the latter stage, and the second RO is installed to remove impurity ions such as boron and organic matter in the treated water in the upstream small desalination chamber. In both cases, a known reverse osmosis membrane device (reverse osmosis membrane module) can be used. The reverse osmosis membrane used for the first and second ROs is not particularly limited, and examples thereof include a cellulose acetate asymmetric membrane and a polyamide composite composite membrane. Moreover, as a form of RO, a spiral module, a hollow fiber module, a flat membrane module, etc. are illustrated.
[0025]
In the deionized water production apparatus I, the first RO permeated water first flows into the second small desalting chamber (A) of EDI-1. Next, the effluent of this second small desalting chamber is supplied to the second RO, and then the second RO permeate flows into the first small desalting chamber (K / A) of EDI-1. According to this method, the anion component is removed in the second small desalting chamber (A) of EDI-1, and the effluent water in this small desalting chamber is on the alkali side. For this reason, the dissociation of boron, which is difficult to remove from the water to be treated, progresses, or the presence form of boron changes due to some electrical treatment, and then the second RO and EDI-1 that flow in In one small desalting chamber (K / A), the boron removal efficiency is further increased.
[0026]
(Deionized water production equipment II)
In the deionized water production system II, the first RO and EDI-2 are connected in series in this order, and UVox is installed in the middle of the pipe connecting the upstream small desalination chamber and downstream small desalination chamber. It is a thing. That is, the difference from the deionized water production apparatus I is that the storage tank and the pump are omitted, and UVox is used instead of the second RO. As UVox, any UV lamp capable of irradiating the water to be treated with a wavelength of at least about 185 nm and capable of decomposing organic substances in the water to be treated may be used. UVox is an apparatus that can irradiate ultraviolet rays having a wavelength of around 254 nm, which has a lower ability to decompose organic substances, in addition to ultraviolet rays having a wavelength of usually around 185 nm.
[0027]
In the deionized water production apparatus II, the permeated water of the first RO flows into the second small desalting chamber (A) of EDI-2 at the subsequent stage. Next, the effluent of this second small desalting chamber is supplied to UVox, and then the treated water of UVox flows into the first small desalting chamber (K / A) of EDI-2. According to this method, as in the case of the deionized water production apparatus I, the anion component is removed in the second small demineralization chamber (A) of EDI-2, and the effluent water in the small demineralization chamber is on the alkali side. . For this reason, the dissociation of the organic matter in the water to be treated proceeds, or the presence of the organic matter changes due to some electrical treatment, and then it becomes easy to oxidize with the incoming UVox. Moreover, a part of organic substance is removed in the 2nd small desalination chamber (A) of EDI-2. Subsequently, the inflowing UVox only needs to oxidize the remaining organic matter, and the oxidation efficiency is improved.
[0028]
(Deionized water production equipment III)
In the deionized water production apparatus III, the first RO and the EDI-1 are connected in series in this order, and the second RO and the EDI-1 are connected in the middle of the piping connecting the upstream small desalination chamber and the downstream small desalination chamber. The UVox is installed in series in this order from the upstream side. That is, the difference from the deionized water production apparatus I is that UVox is further installed in front of the first small desalination chamber of EDI-1 on the rear stage side of the second RO.
[0029]
In the deionized water production apparatus III, the first RO permeate first flows into the second small desalting chamber (A) of EDI-1. Next, the effluent of this second small desalination chamber is supplied to the second RO, the second RO permeate is supplied to UVox, and then the UVox treated water is supplied to the first small desalination chamber (K / A) of EDI-1. Inflow. According to this method, in addition to the same effect as the deionized water production apparatus I, the supply water to the UVox is the RO permeate, so that another part of the organic matter is further removed in the second RO, and the UVox Is more efficient by simply oxidizing the remaining organic matter. Further, carbon dioxide gas generated by UVox oxidative decomposition is reduced, and the load on the first small desalting chamber (K / A) of EDI-1 in the subsequent stage is reduced.
[0030]
As a modification of the deionized water production apparatus III, the installation order of the second RO and UVox can be exchanged. That is, the effluent of the second small desalination chamber of EDI-1 is supplied to UVox, the treated water of UVox is supplied to the second RO, and then the second RO permeated water is supplied to the first small desalination chamber (K / Flows into A). However, although organic matter is decomposed by UVox in the previous stage, the carbon dioxide gas of the decomposed product cannot be removed by the second RO, and it becomes a load on the first small desalination chamber (K / A) of EDI-1, Since the acid is generated and the treated water does not become the alkali side, the deionized water production apparatus III is preferable because the boron cannot be effectively removed by the second RO.
[0031]
In addition, an ultrafiltration membrane device or a microfiltration membrane device can be installed in the subsequent stage of the deionized water production apparatuses I to III. That is, if the effluent from the first small desalination chamber of EDI-1 or EDI-2 is further processed by an ultrafiltration membrane device or a microfiltration membrane device, the fine particles in the deionized water can be significantly reduced. Known ultrafiltration membrane devices and microfiltration membrane devices can be used.
[0032]
(Deionized water production equipment IV)
As shown in FIG. 2, the deionized water production apparatus IV is a comprehensive system 50 that obtains deionized water from the water to be treated and includes a recovery system. The deionized water production apparatus IV (symbol 50) is roughly divided into an EDI-1 pre-treatment part 42, an EDI-1 treatment part 43, and an EDI-1 post-treatment part 44. The EDI-1 pre-treatment part 42 is formed by connecting a decarboxylation tower 31, a pump 32, and a first reverse osmosis membrane device 33 in series from the upstream side. The concentrated water line of the first reverse osmosis membrane device 33 is further connected in the order of the storage tank 39, the pump 40 and the recovered reverse osmosis membrane device 41. The recovery reverse osmosis membrane device 41 does not necessarily need the independent tank 39 and the pump 40, and can be directly operated by the pump 32. Moreover, pH adjustment by acid injection etc., scale generation | occurrence | production prevention agent, or a scale dispersing agent etc. can also be inject | poured into the water supply to the collection | recovery reverse osmosis membrane apparatus 41 as needed. In this portion 42, impurity ions are roughly removed from the water to be treated, the load of EDI-1 in the subsequent stage is reduced, and the concentrated water of the first reverse osmosis membrane device 33 is recovered by the recovery reverse osmosis membrane device 41 to be treated. Return to treated water. The decarbonation tower 31 is installed to remove dissolved gas components such as carbonic acid in the raw water, particularly carbonic acid, and a known decarbonation tower or vacuum degassing tower can be used.
[0033]
The EDI-1 treatment part 43 is a small desalination chamber upstream of EDI-1 (second small desalination chamber) d. ₂ , D _Four , D ₆ , D ₈ , Storage tank 27, pump 25, second reverse osmosis membrane device 34, ultraviolet oxidation device 35, membrane decarboxylation device 36, downstream small desalination chamber (first small desalination chamber) d of EDI-1 ₁ , D _Three , D _Five , D ₇ Are connected in order. In the figure, the upstream small desalination chamber (second small desalination chamber) and the downstream small desalination chamber (first small desalination chamber) of EDI-1 are shown separated from each other. This is a simplified display for the sake of convenience, and is actually as described in FIG. Further, the concentrated water flowing out from these small desalting chambers shown in the figure is the same as the concentrated water flowing out from the EDI-1 concentration chamber. These concentrated waters are collected together with the concentrated water of the second reverse osmosis membrane device 34 and returned to the water to be treated.
[0034]
The removal action of the impurity ions in the EDI-1 treatment portion 43 is as described above. Here, a membrane decarboxylation device 36 is further installed at the subsequent stage of the ultraviolet oxidation device 35, and the treated water generated by the ultraviolet oxidation is treated. The carbon dioxide gas is removed. As the membrane decarboxylation device 36, a known membrane decarboxylation device can be used. The deaeration membrane used in the membrane decarboxylation device 36 is a porous membrane or a non-porous membrane made of a hydrophobic material, and has a characteristic of allowing gas to permeate but not liquid to permeate. Examples of the material of the deaeration film include a porous film or a non-porous film made of polypropylene, polyethylene, polymethylpentene, silicon resin, fluorine resin, or the like. In this case, a decarboxylation tower can be used instead of the membrane decarboxylation device, but a membrane decarboxylation device is preferable in order to maintain the quality of the treated water. In other words, since the membrane decarboxylation device depressurizes and deaerates the opposite side of the membrane through which the treated water flows, the treated water is not easily contaminated in the device, which is convenient for degassing the permeated water of the reverse osmosis membrane. is there. On the other hand, since the decarbonation tower blows air into the water to be treated, there is a possibility that contaminants in the air may be transferred to the water to be treated, and it is not a good idea to use it for the permeated water of the reverse osmosis membrane.
[0035]
The EDI-1 post-stage processing portion 44 includes an ultrafiltration device 38 and a recovery system 38 that recovers the used water used at the point of use (use point) by the deionized water. The ultrafiltration device 37 removes fine particles from the EDI treated water, while returning the concentrated water to the treated water to improve the water recovery rate. The recovered water recovered by the recovery system 38 is also returned to the water to be treated.
[0036]
【Example】
EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.
Experimental example 1
The influence of the pressure in the first small desalting chamber and the pressure in the second small desalting chamber of the electric deionized water production apparatus shown in FIG. 1 on the quality of the treated water was examined. That is, under the following apparatus specifications and operating conditions, electric deionized water production comprising three deionization modules (six small demineralization chambers) arranged in parallel with the same configuration as shown in FIG. Water was passed through the desalting chamber and the concentration chamber of the apparatus, and after steady operation 10 minutes after the start of operation, the inlet pressure P1 and outlet pressure P2 of the second small desalting chamber (upstream side), the first small desalting chamber ( The inlet pressure P3 and the outlet pressure P4 on the downstream side were changed as shown in Table 1 while operating with the pump 25 and the valves 21 and 22, and then the treated water was collected and the water quality was examined. The results are shown in Table 1. In addition, the supply pressure (P1) of to-be-treated water is set to 0.15 MPa (gauge pressure) for No. (experiment number) 1 to 8, and the supply pressure of to-be-treated water (No. 9 to 11) P1) was 0.25 MPa (gauge pressure). The unit of water quality is MΩ-cm and the unit of pressure is 10 ^-1 MPa (gauge pressure).
[0037]
-Treated water and concentrated water; Permeated water obtained by treating industrial water with a reverse osmosis membrane device
・ Resistivity of water to be treated: 0.31 MΩ-cm
・ First small desalination chamber: width 300mm, height 600mm, thickness 3mm
First ion exchange resin filled with small desalting chamber; mixed ion exchange resin of anion exchange resin (A) and cation exchange resin (K) (mixing ratio is A: K = 1: 1 by volume)
・ Second small desalination chamber; width 300mm, height 600mm, thickness 8mm
・ Second small desalination chamber filled ion exchange resin; anion exchange resin
・ Flow rate of the entire device: 1m ^Three / H.
[0038]
[Table 1]

[0039]
As is clear from Table 1, when the test numbers 4 to 7, 10 and 11 are in the relationship of P3 ≧ P1 and P4 ≧ P2, the water quality of the treated water is not deteriorated. That is, stable water quality is obtained when the total pressure in the first small desalting chamber (downstream side) is higher than the total pressure in the second small desalting chamber (upstream side). This is because the second small desalting chamber and the first small desalting chamber are adjacent to each other, and the effluent water from the second small desalting chamber is supplied to the first small desalting chamber. When the pressure in the second small desalting chamber is higher than the pressure in the first small desalting chamber as in the case of the above, leakage of ions and liquids from the second small desalting chamber to the first small desalting chamber occurs. It is estimated that this has led to a decline in
[0040]
Experimental example 2
The operation was continued in Experiment No. 5 in Experimental Example 1, and the changes in the organic matter content (μg-c / L), boron content (μg / L), and the number of fine particles in the treated water for 120 days were examined. The results are shown in FIG. The treated water quality after 120 days was maintained at 17.5 MΩ-cm 2. The number of fine particles is the number of particles having a particle diameter of 0.07 μm or more per ml (× 10 ^Four ).
[0041]
From FIG. 3, although the deterioration of the quality of treated water was not recognized, the organic matter content, the boron content, and the number of fine particles were fluctuating, and the removal was insufficient.
[0042]
Experimental example 3
The operation of Experiment No. 5 in Experimental Example 1 was continued, and the variation of the boron content (μg / L) in the treated water for 40 days was examined. The results are shown in FIG. In FIG. 1, a reverse osmosis membrane device is installed in the middle of the pipe 13a connecting the outflow line of the second small desalination chamber and the inflow line of the first small desalination chamber in addition to the condition of experiment number 5 (experiment The same experiment was performed on the condition where the reverse osmosis membrane device was installed in the treated inflow line 11 under the conditions of No. 12) and Experiment No. 5 (Experiment No. 13). The experiment number 12 corresponds to the above-mentioned “deionized water production apparatus I”, and the experiment number 13 corresponds to a multi-stage (two-stage) installation of a conventional so-called pretreatment reverse osmosis membrane apparatus. The results are shown in FIG.
[0043]
From FIG. 4, when the reverse osmosis membrane device was installed in the front stage of the electric deionized water production device, there was almost no effect of removing boron, whereas the experiment number 12 which is the present embodiment is Removal was much better.
[0044]
Experimental Example 4
The operation was continued in Experiment No. 5 in Experimental Example 1, and the variation of the organic matter content (μg / L) in the treated water for 40 days was examined. The results are shown in FIG. In FIG. 1, an ultraviolet oxidation apparatus is installed in the middle of the pipe 13a connecting the outflow line of the second small desalination chamber and the inflow line of the first small desalination chamber in addition to the condition of experiment number 5 (experiment number). The same experiment was carried out on the inflow line 11 to be treated under the conditions of 14) and Experiment No. 5 (Experiment No. 15). Experiment number 14 corresponds to the above-mentioned “deionized water production apparatus II”. The results are shown in FIG.
[0045]
From FIG. 5, when an ultraviolet oxidation apparatus was installed in the front stage of the electric deionized water production apparatus (experiment number 15), although there was an effect of removing organic substances, it was compared with experiment number 14 which is the present embodiment example. It was inferior.
[0046]
Experimental Example 5
In Experiment No. 12 in Experimental Example 3, the ultraviolet oxidizer was installed in the downstream of the reverse osmosis membrane device and in front of the first small desalination chamber, and the organic matter content in the treated water for 40 days (μg-c / L), variation in boron content (μg / L) and the number of fine particles (pieces) were examined (Experiment No. 16). A similar experiment was conducted when the positions of the reverse osmosis membrane device and the ultraviolet oxidation device were interchanged (experiment number 17). The experiment number 16 corresponds to the above-mentioned “deionized water production apparatus III”, and the experiment number 17 corresponds to the “modified example of the deionized water production apparatus III”. The results are shown in FIG. Further, the variation of the number of fine particles (pieces) was performed only for the experiment number 16, and the result is shown in FIG.
[0047]
From FIG. 6, in Experiment No. 16, the water supplied to the ultraviolet oxidizer is the permeated water of the reverse osmosis membrane device, so a part of the organic matter is removed by the reverse osmosis membrane device, and the ultraviolet oxidizer oxidizes the remaining organic matter. The removal effect of organic matter is extremely high. Moreover, since the water to be treated in the reverse osmosis membrane device is alkali, boron is easily dissociated and is sufficiently removed by the reverse osmosis membrane device. On the other hand, in Experiment No. 17, acid is generated in the ultraviolet oxidizer, and the water to be treated in the reverse osmosis membrane device is not alkali, so the boron component is not sufficiently removed by the reverse osmosis membrane device.
[0048]
Experimental Example 6
An ultrafiltration membrane device was installed after the electric deionized water production apparatus of Experiment No. 16 in Experimental Example 5 and operated, and the fluctuation of the number of fine particles in the treated water for 40 days was examined (Experiment No. 18). The results are shown in FIG. The number of fine particles is indicated by the number of fine particles having a particle diameter of 0.07 μm or more in 1 ml.
[0049]
From FIG. 7, the number of fine particles in the deionized water is remarkably reduced by installing the ultrafiltration membrane device at the subsequent stage of the electric deionized water production apparatus.
[0050]
【The invention's effect】
According to the present invention (1), in the electric deionized water production apparatus, the number of concentration chambers per demineralization chamber filled with an ion exchanger can be reduced to about half of the conventional one, and the electric resistance is remarkably increased. Can be reduced. In addition, the ion exchanger filled in at least one of the two small desalting chambers is a cation exchange with a single ion exchanger or an anion exchanger such as only an anion exchanger or only a cation exchanger. The thickness of the desalting chamber filled with the ion exchanger can be set to an optimum thickness for reducing electric resistance and obtaining high current efficiency. In addition, even if the amount of treated water increases at the beginning of operation and the amount of treated water increases and the pressure in the upstream small desalination chamber rises, the downstream small desalination chamber pressure is reduced to the upstream small desalination chamber. The pressure in the salt chamber can always be increased, and ion migration from the upstream small desalination chamber to the downstream small desalination chamber, leakage of liquid, etc. can be prevented, and high-purity water quality can be obtained more stably. .
[0051]
According to the present invention (2), the ion exchanger filled in one small desalting chamber is an anion exchanger, and the ion exchanger filled in the other small desalting chamber is replaced with a cation exchanger and an anion exchange. In the case of a body mixture, an anionic component is removed in one (upstream side) small desalting chamber, and the outflow water of this small desalting chamber is on the alkali side. For this reason, the dissociation of boron and organic matter in the water to be treated proceeds, or the presence form of boron and organic matter changes due to some electrical treatment, and the reverse osmosis membrane device that flows in further improves the boron removal efficiency. The organic matter is easily oxidized by UVox. Further, a part of the organic substance is removed in the second small desalting chamber of the electric deionized water production apparatus, and the removal efficiency is improved because the remaining organic substance may be oxidized in the next flowing UVox. Therefore, it is possible to cope with the deterioration of the quality of the water to be treated, such as natural phenomena such as drought, and impurities from the production process of the factory.
[0052]
According to this invention (3), the microparticles | fine-particles in to-be-processed water which cannot be removed with a reverse osmosis membrane apparatus and an electrical deionized water manufacturing apparatus can be removed.
According to the present invention (4), it is possible to sufficiently treat water to be treated containing a large amount of anion components, particularly water to be treated containing a large amount of weakly acidic components such as silica and carbonic acid, and two small desaltings. If a reverse osmosis membrane device or an ultraviolet oxidation device is installed in the middle of the piping connecting the chambers, boron and organic acids in the water to be treated can be efficiently removed.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an electrical deionized water production apparatus used in the present invention.
FIG. 2 is a block diagram showing a deionized water production apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram showing the relationship between the number of operating days and the organic matter content in Experiment No. 5.
4 is a graph showing the relationship between the number of operating days and boron content obtained in Experimental Example 3. FIG.
5 is a graph showing the relationship between the number of operating days and the organic matter content obtained in Experimental Example 4. FIG.
6 is a graph showing the relationship between the number of operating days and the organic matter content obtained in Experimental Example 5. FIG.
7 is a diagram showing the relationship between the number of operating days and the number of fine particles obtained in Experimental Example 5 and Experimental Example 6. FIG.
FIG. 8 is a schematic view of a conventional electric deionized water production apparatus.
[Explanation of symbols]
D, D ₁ ~ D _Four 104 Desalination chamber
d ₁ , D _Three , D _Five , D ₇ The first small desalination chamber
d ₂ , D _Four , D ₆ , D ₈ Second small desalination chamber
1,105 Concentration chamber
2, 112, 113 Electrode chamber
3, 101 Cationic membrane
4,102 Anion membrane
5 Intermediate ion exchange membrane
6, 109 cathode
7, 110 Anode
8, 103 Ion exchanger
10, 100 Electric deionized water production equipment
11, 111 Untreated water inflow line
12 Process water outflow line of the second small desalination chamber
13 Processed water inflow line of the first small desalination chamber
14,114 Deionized water outflow line
15, 115 Concentrated water inflow line
16, 116 Concentrated water outflow line
17, 117 Electrode water inflow line
18, 118 Electrode water outflow line
21, 22 Valve
23, 24, 26 Piping
25, 32, 40 pump
27, 39 Storage tank
31 Decarboxylation tower
33 First reverse osmosis membrane device
34 Second reverse osmosis membrane device
35 UV oxidation equipment
36 Membrane decarboxylation device
37 Ultrafiltration membrane device
38 Collection system
41 Recovery reverse osmosis membrane device

Claims (4)

一側のカチオン交換膜、他側のアニオン交換膜及び当該カチオン交換膜と当該アニオン交換膜の間に位置する中間イオン交換膜で区画される２つの小脱塩室にイオン交換体を充填して脱塩室を構成し、前記カチオン交換膜、アニオン交換膜を介して脱塩室の両側に濃縮室を設け、これらの脱塩室及び濃縮室を陽極と陰極の間に配置して形成され、前記一方の小脱塩室の流出管は他方の小脱塩室の流入管に接続され、該２つの小脱塩室を接続する配管途中にポンプを設置してなる電気式脱イオン水製造装置を有することを特徴とする脱イオン水製造装置。An ion exchanger is filled in two small desalting chambers partitioned by a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane. Constructing a desalination chamber, providing a concentrating chamber on both sides of the desalting chamber via the cation exchange membrane and the anion exchange membrane, these desalting chambers and concentrating chambers are arranged between the anode and the cathode, An electric deionized water production apparatus in which the outflow pipe of the one small desalination chamber is connected to the inflow pipe of the other small desalination chamber, and a pump is installed in the middle of the pipe connecting the two small desalination chambers An apparatus for producing deionized water, comprising: 一側のカチオン交換膜、他側のアニオン交換膜及び当該カチオン交換膜と当該アニオン交換膜の間に位置する中間イオン交換膜で区画される２つの小脱塩室にイオン交換体を充填して脱塩室を構成し、前記カチオン交換膜、アニオン交換膜を介して脱塩室の両側に濃縮室を設け、これらの脱塩室及び濃縮室を陽極と陰極の間に配置して形成され、前記一方の小脱塩室の流出管は他方の小脱塩室の流入管に接続され、該２つの小脱塩室を接続する配管途中に逆浸透膜装置、紫外線酸化装置及び脱気膜装置から選ばれる１種以上を設置してなる電気式脱イオン水製造装置を有することを特徴とする脱イオン水製造装置。An ion exchanger is filled in two small desalting chambers partitioned by a cation exchange membrane on one side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane. Constructing a desalination chamber, providing a concentrating chamber on both sides of the desalting chamber via the cation exchange membrane and the anion exchange membrane, these desalting chambers and concentrating chambers are arranged between the anode and the cathode, The outflow pipe of the one small desalination chamber is connected to the inflow pipe of the other small desalination chamber, and a reverse osmosis membrane device, an ultraviolet oxidation device, and a degassing membrane device are installed in the middle of the pipe connecting the two small desalination chambers. A deionized water production apparatus comprising an electric deionized water production apparatus in which at least one selected from the above is installed. 前記電気式脱イオン水製造装置の後段に、限外濾過膜装置又は精密濾過膜装置を設置し、前記電気式脱イオン水製造装置の処理水中の微粒子を更に除去することを特徴とする請求項１又は２記載の脱イオン水製造装置。The ultrafiltration membrane device or the microfiltration membrane device is installed at the subsequent stage of the electric deionized water production device, and further the fine particles in the treated water of the electric deionized water production device are further removed. The deionized water production apparatus according to 1 or 2. 前記中間イオン交換膜と前記他側のアニオン交換膜で区画される一方の小脱塩室に充填されるイオン交換体は、アニオン交換体であり、前記一側のカチオン交換膜と前記中間イオン交換膜で区画される他方の小脱塩室に充填されるイオン交換体は、カチオン交換体とアニオン交換体の混合体であることを特徴とする請求項１又は２記載の脱イオン水製造装置。The ion exchanger filled in one small desalting chamber partitioned by the intermediate ion exchange membrane and the other side anion exchange membrane is an anion exchanger, and the one side cation exchange membrane and the intermediate ion exchange 3. The deionized water production apparatus according to claim 1 or 2, wherein the ion exchanger filled in the other small demineralization chamber partitioned by a membrane is a mixture of a cation exchanger and an anion exchanger.

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