JP4183161B2

JP4183161B2 - Hollow fiber membrane module and hollow fiber membrane module unit

Info

Publication number: JP4183161B2
Application number: JP2002031415A
Authority: JP
Inventors: 禎仁中原; 好恵中原; 哲也取違; 規孝柴田; 康雄小田
Original assignee: Mitsubishi Chemical Corp; Mitsubishi Rayon Co Ltd
Current assignee: Mitsubishi Chemical Corp
Priority date: 2002-02-07
Filing date: 2002-02-07
Publication date: 2008-11-19
Anticipated expiration: 2022-02-07
Also published as: JP2003230819A

Description

【０００１】
【発明の属する技術分野】
本発明は、液体の濾過等に好適に利用し得る中空糸膜モジュールに関する。
【０００２】
【従来の技術】
中空糸膜モジュールは、無菌水、飲料水、高純度水等の製造、或いは空気の浄化等の広範囲の分野で使用されており、近年ではこれらの精密濾過用途に加えて下水処理場における二次処理、三次処理や、浄化槽における固液分離、産業廃水中のＳＳ成分（懸濁物質）の固液分離等のように、高汚濁性水の処理用途への適用もなされつつある。
【０００３】
高汚濁性水濾過の用途に適した中空糸膜モジュールとしては、特開平４−３３４５２９号公報や特開平５−２３５５０号公報、特開平１１−１７９１６２号公報、特開２０００−２２９２２５号公報等には、ハウジング内部にシート状の中空糸膜束の端部を収容し、固定用樹脂を用いて固定してなる中空糸膜モジュールが開示されている。
これらの中空糸膜モジュールの膜面に対し、被処理液の流れや気泡を当てて洗浄を行いつつ濾過を行うと、膜面が閉塞することを防ぎつつ、長期間濾過を行うことができる。
【０００４】
これら中空糸膜モジュールにおいて、中空糸膜固定用の樹脂と中空糸膜との境となる中空糸膜縁部で破断が発生しやすい。これらの破断は、高汚濁性水濾過時に、中空糸膜の揺動や弛緩することによる中空糸膜の折れ曲がりから起こる事が多い。中空糸膜の破断や折損を防止する手段として、例えば特開平４−３３４５２９号公報、特開平５−２３５５０号公報には、保護弾性樹脂層へ中空糸膜を包埋させ、さらに中空糸膜の外周部に広がりを抑制する保護ネット材を配置させる方法が記載されている。
【０００５】
また、特開平１１−１７９１６２号公報には、中空糸膜束の端部を接着剤により固定し、中空糸膜束の端部の周囲を弾性体及び熱収縮チューブにより取り囲んだ後、加熱し収縮させて弾性体を中空糸膜束の外周部に接触させ、中空糸膜が潰れない程度に中空糸膜を押圧して、支持する方法が記載されている。
【０００６】
特開２０００−２２９２２５号公報には、中空糸膜束の、ポッティング剤により固定される表面の、ポッティング剤により固定される部分の縁部を少なくとも含む箇所に、弾性を有する応力緩和部材が設けられている。
【０００７】
【発明が解決しようとする課題】
しかしながら、特開平４−３３４５２９号公報、特開平５−２３５５０号公報に記載の方法は、保護ネット材が柔らかい場合は、中空糸膜の折損が保護弾性樹脂層の界面で発生することがあり、また、保護ネット材が堅い場合は、保護ネット材の先端部に、中空糸膜が接触することで摩擦による亀裂が生ずることがあった。
また、単に折れ曲がりの発生を防ぐために中空糸膜の広がりを抑制しようとすると、締め付けにより中空糸膜同士の間に適度な隙間を保てず、洗浄効果が低下し、非濾過水中の繊維状夾雑物や固形物が中空糸膜に絡み付き、洗浄が困難となる場合があった。
【０００８】
特開平１１−１７９１６２号公報、特開２０００−２２９２２５号公報に記載の方法は、弾性体により囲まれた中空糸膜が、曝気処理等により揺動される力が更に加わることで、中空糸膜の潰れが発生する場合や、また特に、例えば汚泥のような、中空糸膜が流動抵抗を大きく受けるような流体を濾過する場合には、弾性体の界面にて、中空糸膜の折損が発生する場合があった。
【０００９】
本発明者らは、上記課題を解決すべく検討した結果、種々の使用条件下においても中空糸膜の折損が発生しにくい中空糸膜モジュールを見出し、本発明を完成させた。
【００１０】
【課題を解決するための手段】
すなわち本発明の要旨は、複数の中空糸膜の両端部が、２つの相対するハウジングに、固定部材同士の間隔が該中空糸膜の長さよりも短い間隔で固定され、該固定部材の近傍に、曲率半径５ｍｍ以上の曲面を有する部材が設けられてなる中空糸膜モジュールであって、前記曲面を有する部材と、前記曲面を有する部材に最も近い中空糸膜との間隔が３〜５０ｍｍであり、前記曲面を有する部材の前記中空糸膜に接触し得る部位の中で中空糸膜に最も遠い部位と、該最も遠い部位に最も近い中空糸膜の根元部分との距離が１００ｍｍ以下であるとともに、該最も遠い部位と該最も近い中空糸膜の根元部分とを結ぶ直線と、該最も近い中空糸膜の繊維軸に垂直な面とがなす角度が６０度以上である中空糸膜モジュールである。
【００１１】
また、前記曲面を有する部材が弾性体であると、中空糸膜と接触した際の応力をより緩和できるため好ましい。
また、前記複数の中空糸膜をシート状とすると、本発明による中空糸膜の破損防止効果が顕著に発揮される。
また、前記曲面を有する部材が、前記ハウジングと一体化されていると、設置が容易であるため好ましい。
【００１２】
また、前記曲面を有する部材が前記中空糸膜の根元部分を完全に囲うように配されると、中空糸膜の根元部分に夾雑物が絡み付き難くなるため好ましい。
また、前記中空糸膜がポリフッ化ビニリデン、ポリスルホン、ポリアクリロニトリルのいずれかの素材からなると、本発明による中空糸膜の破損防止効果が特に顕著に発揮される。
【００１３】
本発明の第二の要旨は、本発明の中空糸膜モジュールを、横方向及び／又は縦方向に複数個並べて配置してなる中空糸膜モジュールユニット、である。
ここで、前記中空糸膜の長手方向が鉛直方向に配置されてなると、本発明による中空糸膜の破損防止効果が顕著となる。また、前記曲面を有する部材が、前記相対するハウジングのうち、上方に位置するハウジングの前記固定部材近傍にのみ設けられていると、より少ない構成部材で確実に中空糸膜の破損を防止することができる。
【００１４】
【発明の実施の形態】
以下、本発明を詳しく説明する。図１は、本発明の中空糸膜モジュールの一例を表す概略図である。
本発明の中空糸膜モジュール１は、複数の中空糸膜３の両端部が、２つの相対するハウジング２に、固定部材４同士の間隔が中空糸膜３の長さよりも短い間隔で固定されてなるものであり、中空糸膜３が若干の弛緩を持つように配置されるため、洗浄性が良好となる。弛緩間隔としては、固定部材４間距離の５％以下とすることが好ましく、３％以下とすることがより好ましい。
ハウジング２の少なくとも一端には、図示しないがハウジング２に内包される処理液通過のための内部路に連通し、外部に開口した配管が設けられている。
【００１５】
ここで、固定部材４の近傍に、曲率半径５ｍｍ以上の曲面を有する部材６を設けることにより、中空糸膜が揺動しても、曲面に沿って曲線を描く状態となるため、中空糸膜の過度の折れ曲がりを防止し、中空糸膜が破損することを防止することができる。
【００１６】
曲面を有する部材６は、外周面全部、あるいは中空糸膜と接触し得る部位に、中空糸膜に向かって凸となるような曲面を有する部材である。形状としてはパイプ状物、パイプ状物と板状体の接合体、板状体の一部を曲面としたもの等を例として挙げることができる。図２〜図５は、本発明に使用する曲面を有する部材６の例を示す断面図である。
【００１７】
なお、曲率半径とは、中空糸膜と接触し得る部位の曲面の断面外周が形成する円弧の半径をいう。なお、円弧が楕円形状の場合は短径をいう。この曲率半径が５ｍｍ以下の場合、中空糸膜が曲面を有する部材に接触した際に応力を緩和しきれず、折損を防止することが困難となる。
【００１８】
ここで、曲面を有する部材と、複数の中空糸膜のうち最外周部に位置し、曲面を有する部材に最も近い中空糸膜との間隔を、３〜５０ｍｍとすることが好ましい。
この間隔が３mm未満の場合、中空糸膜３と曲面を有する部材６との間に隙間がほとんど無くなるため、繊維状夾雑物等が絡みつきやすくなる。一方、５０ｍｍを超える場合、中空糸膜の折れ曲がりを十分に緩和することができなくなる。
この間隔は、５〜３０ｍｍとするとより好ましい。
【００１９】
なお、この間隔とは、曲面を有する部材の中空糸膜に接触し得る部位の中で中空糸膜に最も近い部位と、最外周に位置する中空糸膜の根元の固定部分同士を結んだ線を含み、中空糸膜の長手方向に概略平行となる面との間の間隔をいうものであり、図６の矢印で示すＡの間隔に相当する。すなわち、弛緩して配置された中空糸膜の揺動によって可変する距離をいうものではない。
【００２０】
また、前記曲面を有する部材の前記中空糸膜に接触し得る部位の中で中空糸膜に最も遠い部位と、該最も遠い部位に最も近い中空糸膜の根元部分との距離は、図７の矢印で示すＢの距離に相当するが、あまり長すぎると中空糸膜根元部の保護効果が不十分となることから、１００ｍｍ以下とすることが好ましく、７５ｍｍ以下とすることがより好ましい。
一方、短すぎても長すぎると中空糸膜根元部の保護効果が不十分となることから、１０ｍｍ以上とすることが好ましく、２０ｍｍ以上とすることがより好ましい。
【００２１】
また、曲面を有する部材の中空糸膜に接触し得る部位の中で中空糸膜に最も遠い部位と、最も近い中空糸膜の根元部分とを結ぶ直線と、中空糸膜の繊維軸方向に対して垂直な面とがなす角度、すなわち図７の角度θが６０度以上であると、中空糸膜が曲面を有する部材に接触した際、大きく変形することがなく保護効果が高くなるため好ましく、７０度以上であるとより好ましい。
【００２２】
なお、前述の中空糸膜の繊維軸方向に対して垂直な面とは、複数の中空糸膜が実質的に同一方向を向くように配置されて固定された固定部分において、平均的な繊維軸方向に垂直な面をいうものである。すなわち、たまさかに異なる方向を向いた特定の中空糸膜の繊維軸方向や、弛緩して配置された中空糸膜の中途部分の、可変する繊維軸方向に垂直な面を対象とするものではない。
【００２３】
曲面を有する部材の材質としては、中空糸膜と接触した際の応力を少しでも緩和するため、弾性体を用いることが好ましい。この際、部材全体を弾性体で構成しても構わないし、少なくとも中空糸膜と接触する可能性のある部分の表面を弾性体で覆うようにしても構わない。その例としては、ゴムやシリコン樹脂、ウレタン樹脂等の可撓性樹脂を単独で用いるか、塩化ビニルやアクリロニトリルブタジエンスチレン等の樹脂製支持体の表面に、軟質ウレタンや、ゴム成分を含有した改質樹脂組成物を被覆する等が挙げられる。
【００２４】
本発明の中空糸膜モジュールの形状としては、円筒形状であってもよいが、図１の例のように、複数の中空糸膜によるシート状とするのが、曲面を有する部材と中空糸膜との距離が、中空糸膜束の内と外でさほど差が無くなり、より多くの中空糸膜に応力緩和の効果を及ぼすことができるため好ましい。
曲面を有する部材は、シート状中空糸膜の片面に配置するだけでも本発明の効果は得られるものの、シート状中空糸膜を挟んで両面に配置することが好ましい。
【００２５】
曲面を有する部材は、中空糸膜モジュールのハウジングと別体に設けても構わないが、ハウジングと一体となるように配置すると、曲面を有する部材と中空糸膜モジュールの位置関係を特別に調整することなく配置できるため好ましい。
曲面を有する部材は、固定部材で固定するときに、固定部材に包埋して固定させても良いし、また、モジュール製造の一連の操作が終了した後に、固定部材やハウジングに接着したり、紐やインシュロック等で縛って固定したり、ネジ固定しても良い。また、ハウジングと一体的に成型することも可能である。
【００２６】
また、図８に示すように、曲面を有する部材が中空糸膜の根元部分の周囲を完全に囲うように配すると、中空糸膜の根元部分に向かって非処理液が直接流れ込まなくなり、非処理液中の繊維くず等の夾雑物が絡み難くなるため、より好ましい。
この際、曲面を有する部材により囲まれた部分に空気が溜まることを防止するため、曲面を有する部材に小さな穴やメッシュを設けてもよい。
【００２７】
本発明に用いられる中空糸膜としては、中空糸膜を単にひき揃えたものでもよいが、中空糸膜モジュールの加工性の面から好適な形態としては、中空糸膜束が枷枠体に多条に巻き取られた巻き状物や、中空糸膜を緯糸として用いて編み地としたもの、またはこの編み地を数枚積層するか、編み地を切断せずに適当な長さに折り畳み重ねて積層体としたようなものが挙げられる。積層体とする場合の編み地の積層（折り畳み）枚数は、編み地の厚さ、すなわち中空糸膜の太さや編み地を編成する際の中空糸膜の合糸本数によっても変化するが、通常は１０枚程度までが好ましい。
中空糸膜の長さは２００ｍｍから２０００ｍｍの範囲が、取り扱い性の上で好ましく、３５０mmから１２００mmの範囲がより好ましい。
【００２８】
本発明で用いられる中空糸膜の材質は必ずしも限定はされず、ポリスルホン系樹脂、ポリアクリロニトリル、セルロース誘導体、ポリエチレンやポリプロピレンなどのポリオレフィン、ポリフッ化ビニリデンやポリテトラフルオロエチレンなどのフッ素系樹脂、ポリアミド、ポリエステル、ポリメタクリレート、ポリアクリレートなどを用いることができる。また、これらの樹脂の共重合体や一部に置換基を導入したものであっても良い。さらに、２種以上の樹脂を混合したものであっても良い。
【００２９】
これらの素材のなかで、ポリフッ化ビニリデン、ポリスルホン、ポリアクリロニトリルは、比較的強度が弱いため、本発明の曲面を有する部材の効果がより顕著に発揮される。
【００３０】
なお、濾過膜として使用可能な中空糸膜であれば、その孔径、空孔率、膜厚、外径等は特に限定されるものではないが、外径は２０〜２０００μｍ、孔径は０．００１〜５μｍ、空孔率は２０〜９０％、膜厚は５〜３００μｍの範囲が好適に用いられる。
【００３１】
本発明の中空糸膜モジュールに用いられるハウジング材質としては、機械的強度および耐久性を有するものであればよく、例えばポリカーボネート、ポリスルホン、ポリオレフィン、ＰＶＣ（ポリ塩化ビニル）、アクリル樹脂、ＡＢＳ樹脂、変成ＰＰＥ（ポリフェニレンエーテル）等を用いることができる。使用後に焼却処理が必要な場合には、燃焼により有毒ガスを出さずに、完全燃焼させることのできるポリオレフィン等の炭化水素系の樹脂を材質とするのが好ましい。
【００３２】
前述した本発明の中空糸膜モジュールを横方向及び／又は縦方向に複数個並べて配置した中空糸膜モジュールユニットは、濾過量を大きくできると共に、取り扱い性に優れている。
また、中空糸膜の配置方向を、繊維軸が鉛直方向を向くように配置すると、被処理液の流れや気泡を中空糸膜に当てて洗浄を行う際に、流れの方向が下から上に向かい、それによって中空糸膜は、水平方向に主として揺動する。従って、シート状中空糸膜を挟むように曲面を有する部材を配置することにより、より多くの中空糸膜に応力緩和の効果を及ぼすことができることから、本発明の効果がより顕著に発揮される。
【００３３】
以下、本発明について実施例をあげて説明する。
＜実施例１＞
ポリフッ化ビニリデン中空糸膜（外径１２００μｍ）２８８０本を、固定部材として２液硬化型ウレタン樹脂Ｃ４４０３／Ｎ４２２４（日本ポリウレタン社製）を使用し、ハウジングに固定して図１に示す平型の中空糸膜モジュールを製造した。なお、膜モジュールの固定部材間の距離は３５０ｍｍ、中空糸膜の平均有効長は３６０ｍｍとした。
【００３４】
そして曲面を有する部材として、直径約２０ｍｍの塩ビ製パイプを、中空糸膜の繊維軸方向に直交し、中空糸膜モジュール外周部全周を取り囲むように、ブラケット部材を介してハウジング部に取り付けた。
【００３５】
このとき、曲面を有する部材と、最も近い中空糸膜との間隔（以降、これを間隔Ａと称する）は１３ｍｍ、曲面を有する部材が中空糸膜に接触し得る部位の中で中空糸膜に最も遠い部位と、最も近い中空糸膜の根元部分との距離（以降、これを距離Ｂと称する）は５０ｍｍ、曲面を有する部材が中空糸膜に接触し得る部位の中で中空糸膜に最も遠い部位と、中空糸膜のうち最外周部に位置する中空糸膜の根元部分とを結ぶ直線と、中空糸膜の繊維軸方向に対して垂直な面とがなす角度（以降、これを角度θと称する）は７５度であった。
【００３６】
この中空糸膜モジュールを、固形分濃度ＳＳが１００００ｍｇ／Ｌの活性汚泥中に配設すると共に、中空糸膜モジュールの下方に配置した散気装置から１００ｍ^３／ｍ^２・ｈｒの強度で散気を行いながら、１週間濾過を行った。
【００３７】
その後、中空糸膜モジュールを汚泥中から引き上げ、中空糸膜を目視にて確認したところ、中空糸膜の端部に少量の夾雑物が付着していたが、水洗により容易に除去することができた。また、折れ曲がり箇所は３カ所存在したが、亀裂や破断は認められなかった。
この中空糸膜モジュールの中空糸膜内部に空気を通気可能なようにハウジングにホースを取り付けた後、水中に浸漬し、空気圧が０．０５ＭＰａとなるように調整したところ、中空糸膜からの気泡のリークは認められなかった。
【００３８】
＜実施例２＞
中空糸膜の材質をポリスルホンとし、距離Ａを２１ｍｍ、角度θを６５度とした以外は、実施例１と同様の中空糸膜モジュールを作成し、同様の濾過試験を行った。
その後、中空糸膜モジュールを引き上げ、折れ曲がり状態を目視で観察したところ、中空糸膜の端部に少量の夾雑物が付着していたが、水洗により容易に除去することができた。また、折れ曲がり箇所は３カ所存在したが、亀裂や破断は認められなかった。さらに、実施例１と同様の空気加圧によるリークテストを行った結果、空気のリークも認められなかった。
【００４０】
＜実施例３＞
膜モジュールの固定部材間距離を１１５０ｍｍ、中空糸膜の平均有効長を１１７０ｍｍとし、曲面を有する部材として、図８に示す構造で、幅５ｍｍ、高さ２０ｍｍで、中空糸膜に面する側の先端部が曲率半径５ｍｍである部材をハウジングと一体となるように、中空糸膜外周部全周を取り囲むように配置した以外は、実施例１と同様に中空糸膜モジュールを作成し、同様の濾過試験を行った。
なお、このときの間隔Ａは４ｍｍ、距離Ｂは２２ｍｍ、角度θは６６度であった。
【００４１】
その後、中空糸膜モジュールを引き上げ、折れ曲がり状態を目視で観察したところ、中空糸膜の端部に少量の夾雑物が付着していたが、水洗により容易に除去することができた。また、折れ曲がり箇所は存在せず、亀裂や破断は認められなかった。さらに、実施例１と同様の空気加圧によるリークテストを行った結果、空気のリークも認められなかった。
【００４２】
＜比較例１＞
曲面を有する部材を設けない以外は、実施例１と同様の中空糸膜モジュールを作成し、同様の濾過試験を行った。
その後、中空糸膜モジュールを引き上げ、折れ曲がり状態を目視で観察したところ、中空糸膜の端部に少量の夾雑物が付着していたが、水洗により容易に除去することができた。一方、折れ曲がり箇所が８０カ所存在し、さらに亀裂が入った個所が７箇所、破断した個所が８箇所存在した。
【００４３】
＜比較例２＞
曲面を有する部材を中空糸膜に接触させて配置した以外は実施例１と同様にして中空糸膜モジュールを作成し、同様の濾過試験を行った。
その後、中空糸膜モジュールを引き上げ、折れ曲がり状態を目視で観察したところ、中空糸膜の端部に多量の夾雑物が付着しており、水洗により除去することがでなかった。なお、折れ曲がり箇所は存在せず、亀裂や破断は認められなかった。さらに、実施例１と同様の空気加圧によるリークテストを行った結果、空気のリークも認められなかった。
【００４４】
【発明の効果】
本発明の中空糸膜モジュールによれば、複数の中空糸膜の両端部が、２つの相対するハウジングに、固定部材同士の間隔が中空糸膜の長さよりも短い間隔で固定され、固定部材の近傍に、曲率半径５ｍｍ以上の曲面を有する部材が設けられているので、中空糸膜が適度に揺動して良好に洗浄できると共に、中空糸膜が折れ曲がることにより損傷を受けることがない。
また、曲面を有する部材と中空糸膜との間隔、中空糸膜根元部分までの距離や角度が適切な範囲に設定されているので、中空糸膜の折れ曲がりを効果的に防止し、かつ中空糸膜に繊維くず等の夾雑物が絡み付いて成長することを防止することができる。
また、曲面を有する部材とハウジングを一体とすることにより、部材の設置を容易に行うことができる。
また、曲面を有する部材が中空糸膜の根元部分を完全に囲むようにすると、夾雑物が絡み付くことを防止する効果をより顕著にすることができる。
【図面の簡単な説明】
【図１】本発明の中空糸膜モジュールの一例を示す斜視図である。
【図２】本発明の曲面を有する部材の一例を示す断面図である。
【図３】本発明の曲面を有する部材の別の一例を示す断面図である。
【図４】本発明の曲面を有する部材の別の一例を示す断面図である。
【図５】本発明の曲面を有する部材の別の一例を示す断面図である。
【図６】本発明の曲面を有する部材の設置位置の例を示す断面図である。
【図７】本発明の曲面を有する部材の設置位置の例を示す断面図である。
【図８】本発明の曲面を有する部材の形態の例を示す断面図である。
【符号の説明】
１中空糸膜モジュール
２ハウジング
３中空糸膜
４固定部材
６曲面を有する部材
７最外周に位置する中空糸膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hollow fiber membrane module that can be suitably used for liquid filtration and the like.
[0002]
[Prior art]
Hollow fiber membrane modules are used in a wide range of fields such as the production of aseptic water, drinking water, high-purity water, etc., or purification of air. In recent years, in addition to these microfiltration applications, secondary fibers in sewage treatment plants are used. Application to the treatment of highly polluted water is also being made, such as treatment, tertiary treatment, solid-liquid separation in septic tanks, solid-liquid separation of SS components (suspended substances) in industrial wastewater.
[0003]
As hollow fiber membrane modules suitable for high-contamination water filtration, JP-A-4-334529, JP-A-5-23550, JP-A-11-179162, JP-A-2000-229225, etc. Discloses a hollow fiber membrane module in which an end portion of a sheet-like hollow fiber membrane bundle is accommodated in a housing and fixed using a fixing resin.
When the membrane surface of these hollow fiber membrane modules is filtered while applying a flow of the liquid to be treated or bubbles to perform filtration, the membrane surface can be filtered for a long time while preventing the membrane surface from being blocked.
[0004]
In these hollow fiber membrane modules, breakage tends to occur at the edge of the hollow fiber membrane which is the boundary between the hollow fiber membrane fixing resin and the hollow fiber membrane. These breaks often occur due to bending of the hollow fiber membrane caused by swinging or relaxation of the hollow fiber membrane during high-contamination water filtration. As a means for preventing breakage or breakage of the hollow fiber membrane, for example, in JP-A-4-334529 and JP-A-5-23550, the hollow fiber membrane is embedded in a protective elastic resin layer, A method of disposing a protective net material that suppresses the spread on the outer periphery is described.
[0005]
In JP-A-11-179162, the end of the hollow fiber membrane bundle is fixed with an adhesive, the periphery of the end of the hollow fiber membrane bundle is surrounded by an elastic body and a heat shrinkable tube, and then heated to shrink. The elastic body is brought into contact with the outer peripheral portion of the hollow fiber membrane bundle, and the hollow fiber membrane is pressed and supported to such an extent that the hollow fiber membrane is not crushed.
[0006]
In Japanese Patent Laid-Open No. 2000-229225, an elastic stress relaxation member is provided at a location including at least the edge of the portion fixed by the potting agent on the surface of the hollow fiber membrane bundle fixed by the potting agent. ing.
[0007]
[Problems to be solved by the invention]
However, in the methods described in JP-A-4-334529 and JP-A-5-23550, when the protective net material is soft, breakage of the hollow fiber membrane may occur at the interface of the protective elastic resin layer. Further, when the protective net material is hard, a crack due to friction may occur due to the hollow fiber membrane coming into contact with the tip of the protective net material.
In addition, if an attempt is made to suppress the spread of the hollow fiber membrane in order to prevent the occurrence of bending, an appropriate gap cannot be maintained between the hollow fiber membranes by tightening, the cleaning effect is reduced, and fibrous contamination in the non-filtered water is reduced. In some cases, the product or solid matter entangled with the hollow fiber membrane, making it difficult to clean.
[0008]
In the methods described in JP-A-11-179162 and JP-A-2000-229225, the hollow fiber membrane surrounded by the elastic body is further subjected to a force that is swung by an aeration process or the like. When the crushing of the hollow fiber membrane occurs, or particularly when filtering a fluid such as sludge where the hollow fiber membrane is subjected to a large flow resistance, the hollow fiber membrane is broken at the interface of the elastic body. There was a case.
[0009]
As a result of investigations to solve the above-mentioned problems, the present inventors have found a hollow fiber membrane module in which the hollow fiber membrane is hardly broken even under various use conditions, and completed the present invention.
[0010]
[Means for Solving the Problems]
That is, the gist of the present invention is that both ends of a plurality of hollow fiber membranes are fixed to two opposing housings at intervals shorter than the lengths of the hollow fiber membranes, and in the vicinity of the fixing members. A hollow fiber membrane module provided with a member having a curved surface with a radius of curvature of 5 mm or more , wherein the distance between the member having the curved surface and the hollow fiber membrane closest to the member having the curved surface is 3 to 50 mm The distance between the part farthest from the hollow fiber membrane and the root part of the hollow fiber membrane closest to the farthest part of the part having a curved surface that can contact the hollow fiber membrane is 100 mm or less. A hollow fiber membrane module in which an angle formed by a straight line connecting the farthest part and the root portion of the nearest hollow fiber membrane and a plane perpendicular to the fiber axis of the nearest hollow fiber membrane is 60 degrees or more .
[0011]
In addition, it is preferable that the member having the curved surface is an elastic body because stress at the time of contact with the hollow fiber membrane can be more relaxed.
Moreover, when the plurality of hollow fiber membranes are formed into a sheet shape, the effect of preventing the hollow fiber membranes from being damaged according to the present invention is remarkably exhibited.
In addition, it is preferable that the member having the curved surface is integrated with the housing because installation is easy.
[0012]
Also, the member having a curved surface is disposed so as to surround the complete root portion of the hollow fiber membrane is preferable because impurities hardly entangled at the base portion of the hollow fiber membranes.
Further, when the hollow fiber membrane is made of any material of polyvinylidene fluoride, polysulfone, and polyacrylonitrile, the effect of preventing the hollow fiber membrane from being damaged according to the present invention is particularly remarkably exhibited.
[0013]
The second gist of the present invention is a hollow fiber membrane module unit in which a plurality of the hollow fiber membrane modules of the present invention are arranged in the horizontal direction and / or the vertical direction.
Here, when the longitudinal direction of the hollow fiber membrane is arranged in the vertical direction, the effect of preventing breakage of the hollow fiber membrane according to the present invention becomes remarkable. Further, when the member having the curved surface is provided only in the vicinity of the fixing member of the housing located above among the housings facing each other, it is possible to reliably prevent the hollow fiber membrane from being damaged with fewer constituent members. Can do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below. FIG. 1 is a schematic view showing an example of the hollow fiber membrane module of the present invention.
In the hollow fiber membrane module 1 of the present invention, both ends of a plurality of hollow fiber membranes 3 are fixed to two opposing housings 2 at intervals shorter than the length of the hollow fiber membrane 3 between the fixing members 4. Since the hollow fiber membrane 3 is arranged so as to have a slight relaxation, the detergency becomes good. The relaxation interval is preferably 5% or less of the distance between the fixing members 4, and more preferably 3% or less.
At least one end of the housing 2 is provided with a pipe (not shown) that communicates with an internal path for passing the processing liquid contained in the housing 2 and opens to the outside.
[0015]
Here, by providing a member 6 having a curved surface with a radius of curvature of 5 mm or more in the vicinity of the fixing member 4, even if the hollow fiber membrane oscillates, a curved state is drawn along the curved surface. It is possible to prevent excessive bending of the hollow fiber membrane and breakage of the hollow fiber membrane.
[0016]
The member 6 having a curved surface is a member having a curved surface that is convex toward the hollow fiber membrane at the entire outer peripheral surface or a portion that can come into contact with the hollow fiber membrane. Examples of the shape include a pipe-like object, a joined body of the pipe-like object and the plate-like body, and a part of the plate-like body having a curved surface. 2-5 is sectional drawing which shows the example of the member 6 which has a curved surface used for this invention.
[0017]
In addition, a curvature radius means the radius of the circular arc which the cross-sectional outer periphery of the curved surface of the site | part which can contact with a hollow fiber membrane forms. In addition, when an arc is elliptical shape, it means a minor axis. When the curvature radius is 5 mm or less, the stress cannot be relieved when the hollow fiber membrane comes into contact with a member having a curved surface, and it is difficult to prevent breakage.
[0018]
Here, it is preferable that the space | interval of the member which has a curved surface and the hollow fiber membrane which is located in the outermost periphery part among several hollow fiber membranes and is the nearest to the member which has a curved surface shall be 3-50 mm.
When this distance is less than 3 mm, there is almost no gap between the hollow fiber membrane 3 and the member 6 having a curved surface, so that fibrous impurities and the like are easily entangled. On the other hand, when it exceeds 50 mm, the bending of the hollow fiber membrane cannot be sufficiently relaxed.
This interval is more preferably 5 to 30 mm.
[0019]
In addition, this space | interval is the line | wire which connected the site | part nearest to the hollow fiber membrane in the site | parts which can contact the hollow fiber membrane of the member which has a curved surface, and the fixed part of the root of the hollow fiber membrane located in the outermost periphery. And a space between the surface of the hollow fiber membrane that is substantially parallel to the longitudinal direction of the hollow fiber membrane, and corresponds to a space A indicated by an arrow in FIG. That is, it does not mean a distance that is variable by swinging a hollow fiber membrane that is placed relaxed.
[0020]
Further, the distance between the part of the member having a curved surface that is farthest from the hollow fiber membrane among the parts that can contact the hollow fiber membrane and the root part of the hollow fiber membrane that is closest to the farthest part is as shown in FIG. Although it corresponds to the distance B indicated by the arrow, if it is too long, the protective effect of the hollow fiber membrane root portion becomes insufficient, so it is preferably 100 mm or less, and more preferably 75 mm or less.
On the other hand, if it is too short or too long, the protective effect of the root portion of the hollow fiber membrane becomes insufficient, so that it is preferably 10 mm or more, and more preferably 20 mm or more.
[0021]
Further, among the parts of the curved member that can contact the hollow fiber membrane, the straight line connecting the part farthest to the hollow fiber membrane and the root part of the closest hollow fiber membrane, and the fiber axis direction of the hollow fiber membrane When the hollow fiber membrane comes into contact with a member having a curved surface, the protective effect is high and the protective effect is high when the angle between the vertical surface and the angle θ in FIG. More preferably, it is 70 degrees or more.
[0022]
The plane perpendicular to the fiber axis direction of the hollow fiber membrane described above means an average fiber axis in a fixed portion in which a plurality of hollow fiber membranes are arranged and fixed so as to face substantially the same direction. A surface perpendicular to the direction. In other words, in the case where the fiber axis direction of a specific hollow fiber membrane facing in a slightly different direction or the surface perpendicular to the variable fiber axis direction of the hollow fiber membrane arranged loosely is targeted Absent.
[0023]
As a material of the member having a curved surface, it is preferable to use an elastic body in order to relieve the stress at the time of contact with the hollow fiber membrane as much as possible. At this time, the entire member may be made of an elastic body, or at least the surface of a portion that may come into contact with the hollow fiber membrane may be covered with the elastic body. For example, a flexible resin such as rubber, silicon resin, or urethane resin is used alone, or a modified support containing soft urethane or a rubber component on the surface of a resin support such as vinyl chloride or acrylonitrile butadiene styrene. For example, coating a porous resin composition.
[0024]
The shape of the hollow fiber membrane module of the present invention may be a cylindrical shape, but as shown in the example of FIG. 1, a sheet shape made up of a plurality of hollow fiber membranes is a member having a curved surface and a hollow fiber membrane. And the distance between the hollow fiber membrane bundles is not so much different and the stress relaxation effect can be exerted on more hollow fiber membranes.
The member having a curved surface is preferably disposed on both sides of the sheet-like hollow fiber membrane, although the effect of the present invention can be obtained only by arranging it on one side of the sheet-like hollow fiber membrane.
[0025]
The member having the curved surface may be provided separately from the housing of the hollow fiber membrane module. However, if the member is arranged so as to be integrated with the housing, the positional relationship between the member having the curved surface and the hollow fiber membrane module is specially adjusted. It is preferable because it can be arranged without any problem.
A member having a curved surface may be embedded and fixed in a fixing member when fixed by a fixing member, or after being subjected to a series of operations for module manufacture, adhered to a fixing member or a housing, It may be fixed by tying with a string or an insulation lock, or may be fixed with a screw. It is also possible to mold integrally with the housing.
[0026]
Further, as shown in FIG. 8, when the member having a curved surface is arranged so as to completely surround the base part of the hollow fiber membrane, the non-treatment liquid does not flow directly toward the base part of the hollow fiber membrane, It is more preferable because impurities such as fiber waste in the liquid are less likely to get entangled.
At this time, a small hole or a mesh may be provided in the member having a curved surface in order to prevent air from collecting in a portion surrounded by the member having a curved surface.
[0027]
The hollow fiber membrane used in the present invention may be a simple arrangement of hollow fiber membranes. However, from the viewpoint of processability of the hollow fiber membrane module, a hollow fiber membrane bundle is often provided on the frame body. Rolls wound on strips, knitted fabrics using hollow fiber membranes as wefts, or several layers of these knitted fabrics, or folded to an appropriate length without cutting the knitted fabric And a laminate. The number of layers (folding) of the knitted fabric in the case of a laminated body varies depending on the thickness of the knitted fabric, that is, the thickness of the hollow fiber membrane and the number of combined yarns of the hollow fiber membrane when the knitted fabric is knitted. Is preferably about 10 sheets.
The length of the hollow fiber membrane is preferably in the range of 200 mm to 2000 mm in view of handleability, and more preferably in the range of 350 mm to 1200 mm.
[0028]
The material of the hollow fiber membrane used in the present invention is not necessarily limited. Polysulfone resin, polyacrylonitrile, cellulose derivative, polyolefin such as polyethylene and polypropylene, fluorine resin such as polyvinylidene fluoride and polytetrafluoroethylene, polyamide, Polyester, polymethacrylate, polyacrylate and the like can be used. In addition, copolymers of these resins or those having a substituent introduced into a part thereof may be used. Furthermore, what mixed 2 or more types of resin may be used.
[0029]
Among these materials, polyvinylidene fluoride, polysulfone, and polyacrylonitrile are relatively weak in strength, so that the effect of the member having a curved surface of the present invention is more remarkably exhibited.
[0030]
In addition, as long as it is a hollow fiber membrane that can be used as a filtration membrane, its pore diameter, porosity, film thickness, outer diameter and the like are not particularly limited, but the outer diameter is 20 to 2000 μm, and the pore diameter is 0.001. ˜5 μm, porosity is 20 to 90%, and film thickness is preferably in the range of 5 to 300 μm.
[0031]
The housing material used in the hollow fiber membrane module of the present invention may be any material having mechanical strength and durability. For example, polycarbonate, polysulfone, polyolefin, PVC (polyvinyl chloride), acrylic resin, ABS resin, modified PPE (polyphenylene ether) or the like can be used. When an incineration treatment is required after use, it is preferable to use a hydrocarbon-based resin such as polyolefin that can be completely burned without emitting a toxic gas by combustion.
[0032]
The hollow fiber membrane module unit in which a plurality of the hollow fiber membrane modules of the present invention described above are arranged side by side and / or in the vertical direction can increase the amount of filtration and is excellent in handleability.
In addition, when the arrangement direction of the hollow fiber membrane is arranged so that the fiber axis is oriented in the vertical direction, the flow direction is from bottom to top when washing is performed by applying the flow of the liquid to be treated or air bubbles to the hollow fiber membrane. Oppositely, the hollow fiber membrane mainly oscillates in the horizontal direction. Therefore, by arranging a member having a curved surface so as to sandwich the sheet-like hollow fiber membrane, the effect of the present invention can be exhibited more remarkably because more hollow fiber membranes can have a stress relaxation effect. .
[0033]
Hereinafter, the present invention will be described with reference to examples.
<Example 1>
A flat-type hollow shown in FIG. 1 is obtained by fixing 2880 polyvinylidene fluoride hollow fiber membranes (outer diameter 1200 μm) with a two-component curable urethane resin C4403 / N4224 (manufactured by Nippon Polyurethane) as a fixing member. A yarn membrane module was manufactured. The distance between the fixing members of the membrane module was 350 mm, and the average effective length of the hollow fiber membrane was 360 mm.
[0034]
As a member having a curved surface, a PVC pipe having a diameter of about 20 mm was attached to the housing portion via a bracket member so as to be orthogonal to the fiber axis direction of the hollow fiber membrane and surround the entire outer periphery of the hollow fiber membrane module. .
[0035]
At this time, the distance between the member having the curved surface and the nearest hollow fiber membrane (hereinafter referred to as the interval A) is 13 mm, and the hollow fiber membrane is located in the portion where the member having the curved surface can contact the hollow fiber membrane. The distance between the farthest part and the root part of the nearest hollow fiber membrane (hereinafter referred to as the distance B) is 50 mm, and the distance between the member having a curved surface and the hollow fiber membrane is the most in the hollow fiber membrane. An angle formed by a straight line connecting a distant portion and the root portion of the hollow fiber membrane located at the outermost peripheral portion of the hollow fiber membrane and a plane perpendicular to the fiber axis direction of the hollow fiber membrane (hereinafter referred to as an angle) (referred to as θ) was 75 degrees.
[0036]
The hollow fiber membrane module is disposed in activated sludge having a solid content concentration of 10000 mg / L, and diffused with an intensity of 100 m ³ / m ² · hr from an air diffuser disposed below the hollow fiber membrane module. Filtration was performed for 1 week.
[0037]
Thereafter, the hollow fiber membrane module was lifted from the sludge, and the hollow fiber membrane was visually confirmed. A small amount of contaminants adhered to the end of the hollow fiber membrane, but it could be easily removed by washing with water. It was. Further, although there were three bent portions, no cracks or breaks were observed.
After attaching a hose to the housing so that air can be ventilated inside the hollow fiber membrane of this hollow fiber membrane module, it was immersed in water and adjusted so that the air pressure was 0.05 MPa. No leak was observed.
[0038]
<Example 2>
A hollow fiber membrane module similar to that of Example 1 was prepared and the same filtration test was performed except that the material of the hollow fiber membrane was polysulfone, the distance A was 21 mm, and the angle θ was 65 degrees.
Then, when the hollow fiber membrane module was pulled up and the bent state was visually observed, a small amount of impurities adhered to the end of the hollow fiber membrane, but it could be easily removed by washing with water. Further, although there were three bent portions, no cracks or breaks were observed. Furthermore, as a result of performing a leak test by air pressurization as in Example 1, no air leak was observed.
[0040]
<Example 3 >
The distance between the fixing members of the membrane module is 1150 mm, the average effective length of the hollow fiber membrane is 1170 mm, and the member having a curved surface has a structure shown in FIG. 8 and a width of 5 mm, a height of 20 mm, and the side facing the hollow fiber membrane. A hollow fiber membrane module is prepared in the same manner as in Example 1 except that a member having a radius of curvature of 5 mm is disposed so as to surround the entire outer periphery of the hollow fiber membrane so as to be integrated with the housing. A filtration test was performed.
At this time, the interval A was 4 mm, the distance B was 22 mm, and the angle θ was 66 degrees.
[0041]
Then, when the hollow fiber membrane module was pulled up and the bent state was visually observed, a small amount of impurities adhered to the end of the hollow fiber membrane, but it could be easily removed by washing with water. In addition, there were no bent portions, and no cracks or breaks were observed. Furthermore, as a result of performing a leak test by air pressurization as in Example 1, no air leak was observed.
[0042]
<Comparative Example 1>
Except for not providing a member having a curved surface, a hollow fiber membrane module similar to that in Example 1 was prepared, and a similar filtration test was performed.
Then, when the hollow fiber membrane module was pulled up and the bent state was visually observed, a small amount of impurities adhered to the end of the hollow fiber membrane, but it could be easily removed by washing with water. On the other hand, there were 80 bent points, seven cracked points, and eight broken points.
[0043]
<Comparative example 2>
A hollow fiber membrane module was prepared in the same manner as in Example 1 except that a member having a curved surface was placed in contact with the hollow fiber membrane, and the same filtration test was performed.
Thereafter, the hollow fiber membrane module was pulled up and the bent state was visually observed. As a result, a large amount of contaminants adhered to the end of the hollow fiber membrane and could not be removed by washing with water. In addition, the bending location did not exist and a crack and a fracture | rupture were not recognized. Furthermore, as a result of performing a leak test by air pressurization as in Example 1, no air leak was observed.
[0044]
【The invention's effect】
According to the hollow fiber membrane module of the present invention, both end portions of a plurality of hollow fiber membranes are fixed to two opposing housings at intervals shorter than the length of the hollow fiber membranes. Since a member having a curved surface with a curvature radius of 5 mm or more is provided in the vicinity, the hollow fiber membrane can be swung properly and washed well, and the hollow fiber membrane is not damaged by bending.
The distance between the member and the middle hollow fiber membrane having a curved surface, since the distance and angle to the hollow fiber membrane root portion is set in the proper range, effectively prevent bending of the hollow fiber membrane, and a hollow It is possible to prevent the yarn film from growing by being entangled with impurities such as fiber scraps.
In addition, the member can be easily installed by integrating the member having a curved surface and the housing.
In addition, when the member having a curved surface completely surrounds the base portion of the hollow fiber membrane, the effect of preventing the entanglement of impurities can be made more remarkable.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a hollow fiber membrane module of the present invention.
FIG. 2 is a cross-sectional view showing an example of a member having a curved surface according to the present invention.
FIG. 3 is a cross-sectional view showing another example of a member having a curved surface according to the present invention.
FIG. 4 is a cross-sectional view showing another example of a member having a curved surface according to the present invention.
FIG. 5 is a cross-sectional view showing another example of a member having a curved surface according to the present invention.
FIG. 6 is a cross-sectional view showing an example of an installation position of a member having a curved surface according to the present invention.
FIG. 7 is a cross-sectional view showing an example of an installation position of a member having a curved surface according to the present invention.
FIG. 8 is a cross-sectional view showing an example of the shape of a member having a curved surface according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hollow fiber membrane module 2 Housing 3 Hollow fiber membrane 4 Fixing member 6 Curved member 7 Hollow fiber membrane located in the outermost periphery

Claims

Both ends of the plurality of hollow fiber membranes are fixed to two opposing housings at intervals between the fixing members shorter than the length of the hollow fiber membranes, and curved surfaces having a curvature radius of 5 mm or more in the vicinity of the fixing members. A hollow fiber membrane module in which a member having the curved surface and a hollow fiber membrane nearest to the member having the curved surface are 3 to 50 mm, and the member having the curved surface The distance between the portion farthest from the hollow fiber membrane among the portions that can contact the hollow fiber membrane and the root portion of the hollow fiber membrane closest to the farthest portion is 100 mm or less, and the farthest portion and the A hollow fiber membrane module in which an angle formed by a straight line connecting the root portion of the nearest hollow fiber membrane and a plane perpendicular to the fiber axis of the nearest hollow fiber membrane is 60 degrees or more.

Wherein the plurality of hollow fiber membrane module of claim 1 Symbol mounting the hollow fiber membrane is a sheet-like.

The hollow fiber membrane module according to claim 1 or 2 , wherein a plurality of the hollow fiber membrane modules are arranged side by side in the lateral direction and / or longitudinal direction, the longitudinal direction of the hollow fiber membrane is arranged in the vertical direction, and the member having the curved surface However, the hollow fiber membrane module unit is provided only in the vicinity of the fixing member of the upper housing among the opposing housings.