JP4205984B2

JP4205984B2 - Membrane filtration device and operation method thereof

Info

Publication number: JP4205984B2
Application number: JP2003108178A
Authority: JP
Inventors: 俊文椋橋; 一栄柴田
Original assignee: Sanki Engineering Co Ltd
Current assignee: Sanki Engineering Co Ltd
Priority date: 2003-04-11
Filing date: 2003-04-11
Publication date: 2009-01-07
Anticipated expiration: 2023-04-11
Also published as: JP2004313854A

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば、水道水の製造や産業用水の製造に使用する膜ろ過装置およびその運転方法に関する。
【０００２】
【従来の技術】
従来、この種の膜ろ過装置としては、膜破断を検知する装置を設けることが知られている（例えば、特許文献１〜４参照）。
その一例を図５に示す。
先ず、膜ろ過装置１の構成を説明する。
原水をろ過する中空糸膜モジュール２には、弁５〜１０が設けてある。ろ過時に弁５，６が開放し、洗浄時に弁７，８が開放し、ドレン時に弁８，９が開放するように構成されている。
【０００３】
中空糸膜モジュール２の一次側には、弁５を備えた原水管１１、弁８を備えた排気管１４、弁９を備えた排水管１５、弁１０を備えた膜破断検知管１６をそれぞれ取り付けている。
膜破断検知管１６には、光源１７と受光素子１８とを備えた膜破断検知装置３を取り付けている。膜破断検知装置３は、膜破断検知管１６を通る空気を光源１７と受光素子１８で測定する構成となっている。
【０００４】
中空糸膜モジュール２の二次側には、弁６を備えた膜ろ過水管１２、弁７を備えた空気管１３を取り付けている。
空気管１３には、コンプレッサ４が連絡している。
次に、このように構成された従来の膜ろ過装置１について説明する。
従来の膜ろ過装置１の運転は、ろ過工程、洗浄工程、ドレン工程、満水工程、破断検知工程を繰り返し行っている。
【０００５】
それぞれの水または空気の流れるラインは、下記の通りである。
先ず、ろ過工程では、原水管１１→弁５→中空糸膜モジュール２→弁６→膜ろ過水管１２の経路を経て、原水のろ過処理が為される。
次に、洗浄工程では、コンプレッサ４→空気管１３→弁７→中空糸膜モジュール２→弁８→排気管１４の経路を経て、中空糸膜モジュール２の洗浄処理が為される。
【０００６】
次に、ドレン工程では、弁８→中空糸膜モジュール２→弁９→排水管１５の経路を経て、洗浄工程で使用された洗浄水のドレン処理が為される。なお、ここでは、弁８は、ドレン排水時に空気を入れるために開とする。
次に、満水工程では、原水管１１→弁５→中空糸膜モジュール２の経路を経て、中空糸膜モジュール２内を満水にする処理が為される。なお、ここでは、弁８は、中空糸膜モジュール２内部の空気を大気へ解放するため開とする。
【０００７】
次に、破断検知工程では、空気管１３→弁７→中空糸膜モジュール２→弁１０→膜破断検知管１６→膜破断検知装置３の経路を経て、中空糸膜モジュール２の破断検知処理が為される。
【特許文献１】
特開平１１−３１１５９６号公報
【特許文献２】
特開２０００−１２６５６３号公報
【特許文献３】
特開２０００−３４２９３７号公報
【特許文献４】
特開２００１−２６９５５１号公報
【０００８】
【発明が解決しようとする課題】
しかし、図５に示す従来の膜ろ過装置１においては、膜破断検知装置３が、中空糸膜モジュール２の１つに対して１つ設置されているため、膜ろ過装置１が煩雑となっていた。
また、コンプレッサ４によって圧縮空気を中空糸膜モジュール２に送り、膜破断検知管１６を通る空気を膜破断検出装置３内部の光源１７と受光素子１８で測定しているため、長期間の使用によって膜破断検出装置３の内部が汚れ、誤作動を起こすおそれがあった。
【０００９】
この誤作動を防ぐためには、頻繁に膜破断検出装置３の内部を清掃する必要があった。
なお、特許文献１〜４においても、図５に示す従来の膜ろ過装置１と同様に、膜破断検知装置を中空糸膜モジュールの１つに対して１つ設置する必要があり、膜ろ過装置が煩雑となるという不具合があった。
【００１０】
本発明は、斯かる従来の問題点を解決するため為されたもので、その目的は、膜破断検知を簡便に行うことが可能な膜ろ過装置およびその運転方法を提供することにある。
【００１１】
【課題を解決するための手段】
請求項１に係る発明は、原水をろ過する複数の中空糸膜モジュールと、前記複数の中空糸膜モジュールの一次側に、弁を介して取り付ける原水管と、前記複数の中空糸膜モジュールの一次側に、弁を介して取り付ける排気管と、前記複数の中空糸膜モジュールの一次側に、弁を介して取り付ける排水管と、前記複数の中空糸膜モジュールの一次側に、弁を介して取り付ける膜破断検知管と、水位の上昇速度を測定する水位計と、上昇度合が遅い場合あるいは上昇しない場合には、警報を発し膜破断を報知する手段とを備え、前記膜破断検知管に連絡する膜破断検知水槽と、前記複数の中空糸膜モジュールの二次側に、弁を介して取り付ける膜ろ過水管と、前記複数の中空糸膜モジュールの二次側に、弁を介して取り付ける空気管と、前記空気管に連絡するコンプレッサとを備え、前記複数の中空糸膜モジュールによるろ過時には、前記原水管と前記膜ろ過水管とに設けた弁だけを開放し、前記複数の中空糸膜モジュールの洗浄時には、前記空気管と前記排気管とに設けた弁だけを開放するとともに、前記コンプレッサから前記空気管を介して前記複数の中空糸膜モジュールの二次側に圧縮空気を供給し、前記複数の中空糸膜モジュールの洗浄後の排水時には、前記排気管と前記排水管とに設けた弁だけを開放し、前記複数の中空糸膜モジュールの満水時には、前記原水管と排気管とに設けた弁だけを開放し、前記複数の中空糸膜モジュールの膜破断検出時には、前記空気管と前記膜破断検出管とに設けた弁だけを開放するとともに、前記コンプレッサから前記空気管を介して前記複数の中空糸膜モジュールの二次側に圧縮空気を供給し、前記膜破断検出管を介して流出する水を前記膜破断検知水槽に貯留し、前記膜破断検知水槽の水位の上昇速度を測定し、前記上昇度合いが遅いまたは上昇しない場合に、前記複数の中空糸膜モジュールの膜破断有りと判断するように構成したことを特徴とする。
【００１２】
請求項２に係る発明は、請求項１記載の膜ろ過装置において、前記中空糸膜モジュールの膜破断検出時に供給される前記圧縮空気の圧力は、バブルポイントより低い圧力であることを特徴とする。
請求項３に係る発明は、請求項１記載の膜ろ過装置において、前記膜破断検知水槽は、排水弁を備えた開放型の水槽であり、前記複数の中空糸膜モジュールの膜破断検出時だけ前記排水弁を閉じることを特徴とする。
【００１３】
請求項４に係る発明は、請求項１記載の膜ろ過装置において、前記膜破断検知水槽は、排水弁を備えた密閉型の水槽であり、水位に伴って変動する前記水槽内部の圧力と、前記複数の中空糸膜モジュールの一次側の圧力とが平衡状態になろうとするときの水位を前記水位計で測定することを特徴とする。
請求項５に係る発明は、原水のろ過工程、前記複数の中空糸膜モジュールの洗浄工程、前記複数の中空糸膜モジュールのドレン工程、前記複数の中空糸膜モジュールの満水工程および前記複数の中空糸膜モジュールの膜破断検出工程を順に行う請求項１記載の膜ろ過装置の運転方法であって、前記原水のろ過工程では、前記原水管と前記膜ろ過水管とに設けた弁だけを開放し、原水供給源と前記複数の中空糸膜モジュールとの水位差により前記原水を前記中空糸膜モジュールに加圧送水してろ過水し、前記ろ過水を前記膜ろ過水管を介して導出し、前記複数の中空糸膜モジュールの洗浄工程では、前記空気管と前記排気管とに設けた弁だけを開放するとともに、前記コンプレッサから前記空気管を介して前記複数の中空糸膜モジュールの二次側に圧縮空気を供給し、前記複数の中空糸膜モジュールのドレン工程では、前記排気管と前記排水管とに設けた弁だけを開放し、前記複数の中空糸膜モジュールの一次側の水を排出し、前記複数の中空糸膜モジュールの満水工程では、前記原水管と排気管とに設けた弁だけを開放し、前記複数の中空糸膜モジュールの膜破断検出工程では、前記空気管と前記膜破断検出管とに設けた弁だけを開放するとともに、前記コンプレッサから前記空気管を介して前記複数の中空糸膜モジュールの二次側に圧縮空気を供給し、前記膜破断検出管を介して流出する水を前記膜破断検知水槽に貯留し、前記膜破断検知水槽の水位の上昇速度を測定し、前記上昇度合いが遅いまたは上昇しない場合に、前記複数の中空糸膜モジュールの膜破断有りと判断することを特徴とする。
【００１４】
請求項６に係る発明は、請求項５記載の膜ろ過装置の運転方法において、前記中空糸膜モジュールの膜破断検出工程に供給される前記圧縮空気の圧力は、バブルポイントより低い圧力であることを特徴とする。
【００１５】
【発明の実施の形態】
以下、本発明を図面に示す実施形態に基づいて説明する。
図１は、本発明の第一実施形態に係る膜ろ過装置５０を示す（請求項１〜請求項３に対応する）。
本実施形態に係る膜ろ過装置５０は、膜破断検知管５８に膜破断検知水槽６４を設けた点で、図５に示す従来の膜ろ過装置１とは相違する。
本実施形態に係る膜ろ過装置５０は、原水をろ過する複数の中空糸膜モジュール５１を備えている。中空糸膜モジュール５１は、例えば、孔径が２μｍ程度の外圧中空糸膜を収納した低圧中空糸膜モジュールである。
【００１６】
各中空糸膜モジュール５１の一次側５１ａには、弁５３を備えた原水管５２と、弁５５を備えた排気管５４と、弁５７を備えた排水管５６と、弁５９を備えた膜破断検知管５８とを取り付けている。
各中空糸膜モジュール５１の二次側５１ｂには、弁６１を備えた膜ろ過水管６０と、弁６３を備えた空気管６２とを取り付けている。
【００１７】
膜破断検知管５８は、水位計６５および弁６６を備えた開放型の膜破断検知水槽６４に連絡している。
空気管６２は、圧縮空気を供給するコンプレッサ６７に連絡している。
次に、斯くして構成された本実施形態に係る膜ろ過装置５０を用いて、原水のろ過工程、複数の中空糸膜モジュール５１の洗浄工程、複数の中空糸膜モジュール５１のドレン工程、複数の中空糸膜モジュール５１の満水工程および複数の中空糸膜モジュール５１の膜破断検出工程を順に行う運転方法について説明する（請求項５〜請求項６に対応する）。
【００１８】
先ず、原水のろ過工程では、原水管５２と膜ろ過水管６０とに設けた弁５３，６１だけを開放し、その他の弁５５，５７，５９，６３を閉じる。
原水は、原水供給源と複数の中空糸膜モジュール５１との水位差により中空糸膜モジュール５１の一次側５１ａに加圧送水され、中空糸膜モジュール５１の膜表面に空いた細孔によりろ過され、中空糸膜モジュール５１の二次側５１ｂにろ過水として流出し、膜ろ過水管６０を介して任意の水槽などに貯水される。
【００１９】
次に、原水管５２に設けた弁５３と膜ろ過水管６０に設けた弁６１を閉じた後、複数の中空糸膜モジュール５１の洗浄工程に移行する。
ここでは、空気管６２と排気管５４とに設けた弁６３，５５だけを開放し、コンプレッサ６７から空気管６２を介して中空糸膜モジュール５１の二次側５１ｂに圧縮空気を供給し、中空糸膜モジュール５１の二次側５１ｂから一次側５１ａに圧縮空気を通して膜の逆洗を行う。
【００２０】
上述したように、中空糸膜モジュール５１による膜ろ過では、膜表面に空いた細孔により原水をろ過してろ過水を得ることができる。この細孔を水などの液体で湿潤させ、中空糸膜モジュール５１の二次側５１ｂに、空気で圧力をかけると、ある圧力で細孔内の水が空気により押し出され、中空糸膜モジュール５１の一次側５１ａに、空気が通過する。この圧力をバブルポイントという。バブルポイントは、低圧膜の場合３０ｋＰａ程度である。
【００２１】
したがって、中空糸膜モジュール５１の二次側５１ｂに、バブルポイントより低い圧力をかけた場合、中空糸膜モジュール５１の一次側５１ａに、空気は通過しない。
しかし、膜に破断箇所がある場合、バブルポイントより低い圧力でも破断箇所から中空糸膜モジュール５１の一次側５１ａに、空気が漏れる。
【００２２】
また、洗浄時間は、例えば１５秒程度である。
このような機能を利用して、複数の中空糸膜モジュール５１の洗浄を行う。
次に、弁６３を閉じた後、弁５７を開放して複数の中空糸膜モジュール５１の排水工程に移行する。
ここでは、弁５７を開放することにより、排気管５４を介して空気が複数の中空糸膜モジュール５１の一次側５１ａ内に導入され、複数の中空糸膜モジュール５１の一次側５１ａ内の水が排出される。
【００２３】
次に、弁５７を閉じた後、弁５３を開放して複数の中空糸膜モジュール５１の満水工程に移行する。
ここでは、原水管５２を介して原水が複数の中空糸膜モジュール５１内に流入し、複数の中空糸膜モジュール５１内を原水で満たすことができる。
次に、弁５３，５５を閉じた後、弁５９，６３を開放し、コンプレッサ６７から圧縮空気を複数の中空糸膜モジュール５１の二次側５１ｂに供給することにより、複数の中空糸膜モジュール５１の膜破断検出工程に移行する。
【００２４】
上述したように、中空糸膜モジュール５１の二次側５１ｂに、バブルポイントより低い圧力をかけた場合、中空糸膜モジュール５１の一次側５１ａに、空気は通過しないので、膜破断検知管５８には水のみが通過する。
しかし、膜に破断箇所がある場合、バブルポイントより低い圧力でも破断箇所から中空糸膜モジュール５１の一次側５１ａに、空気が漏れるため、膜破断検知管５８には空気と水の両方が流れる。
【００２５】
このため、膜破断検知管５８を流れる水量が異なり、膜を透過した水を膜破断検知水槽６４に貯留したとき、水位上昇速度が異なる。この水位の上昇速度を水位計６５で測定することにより、膜破断を検出する。
そして、膜破断検知水槽６４の水位の上昇速度を水位計６５により測定する。その結果を、図２に示す。上昇度合が遅い場合あるいは上昇しない場合には、警報を発し膜破断を確認できるようになされている。
【００２６】
なお、膜破断検知水槽６４に設けた弁６６は、複数の中空糸膜モジュール５１の膜破断検出工程の時だけ閉じておく。
以上のように、本実施形態によれば、複数の中空糸膜モジュール５１に対して１つの膜破断検知水槽６４を設置するだけでよいので、従来の膜ろ過装置に比して簡便となる。
【００２７】
また、複数の中空糸膜モジュール５１の二次側５１ｂに、洗浄用のコンプレッサ６７を利用して空気を送ることで、破断時には、膜破断検知水槽６４の水位の上昇が通常に比べて遅い、または上昇せずとして現れるので、破断のチェックが可能となり、モジュール数が多い場合でも対応が可能である。
また、破断の検出に受光素子を用いないため、清掃不良などによる誤作動も起こらない。
【００２８】
また、洗浄は一定サイクルで周期的に行われるために、定期的に破断のチェックができる。
図３は、本発明の第二実施形態に係る膜ろ過装置７０を示す（請求項１〜請求項２、請求項４に対応する）。
本実施形態に係る膜ろ過装置７０は、膜破断検知水槽６４を密閉型にした点で、第一実施形態に係る膜ろ過装置５０とは相違する。
【００２９】
本実施形態に係る膜ろ過装置７０では、第一実施形態に係る膜ろ過装置５０と同様に、複数の中空糸膜モジュール５１の二次側５１ｂに、バブルポイントより低い圧力をかけた場合、複数の中空糸膜モジュール５１の一次側５１ａに、空気は通過しないので、膜破断検知管５８には水のみが通過する。
この際、水位の上昇に伴って膜破断検知水槽６４の内部の圧力は上昇して、供給した空気の圧力と平衡状態となり、水の通過は停止する。
【００３０】
複数の中空糸膜モジュール５１の膜に破断箇所がある場合は、バブルポイントより低い圧力でも破断箇所から複数の中空糸膜モジュール５１の一次側５１ａに、空気が漏れるため、膜破断検知管５８には空気と水の両方が流れる。
このため、膜破断検知水槽６４の内部の圧力が上昇して、空気管６２から送った空気の圧力と平衡状態となったときの水位は、図４に示すように、膜に破断箇所のない場合と比べて低くなる。
【００３１】
このときの水位を水位計６５で測定することにより、膜破断を検出する。または、水位の上昇速度を水位計６５で測定する。もしくは、水位と水位の上昇速度の両方を測定する。
本実施形態においても、第一実施形態に係る膜ろ過装置５０と同様の作用効果を奏することが可能となる。
【００３２】
【発明の効果】
本発明によれば、複数の中空糸膜モジュールに対して１つの膜破断検知水槽を設置するだけで、複数の中空糸膜モジュールの膜破断を検出することができる。
【図面の簡単な説明】
【図１】本発明の第一実施形態に係る膜ろ過装置を示す説明図である。
【図２】本発明の第一実施形態に係る膜ろ過装置における膜破断検出を示すグラフである。
【図３】本発明の第二実施形態に係る膜ろ過装置を示す説明図である。
【図４】本発明の第二実施形態に係る膜ろ過装置における膜破断検出を示すグラフである。
【図５】従来の膜ろ過装置を示す説明図である。
【符号の説明】
５０、７０膜ろ過装置
５１中空糸膜モジュール
５１ａ中空糸膜モジュール５１の一次側
５１ｂ中空糸膜モジュール５１の二次側
５２原水管
５３、５５、５７、５９、６１、６３、６６弁
５４排気管
５６排水管
５８膜破断検知管
６０膜ろ過水管
６２空気管
６４膜破断検知水槽
６５水位計
６７コンプレッサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a membrane filtration device used for the production of tap water and industrial water, for example, and an operation method thereof.
[0002]
[Prior art]
Conventionally, as this type of membrane filtration device, it is known to provide a device for detecting membrane breakage (see, for example, Patent Documents 1 to 4).
An example is shown in FIG.
First, the configuration of the membrane filtration device 1 will be described.
Valves 5 to 10 are provided in the hollow fiber membrane module 2 for filtering raw water. The valves 5 and 6 are opened during filtration, the valves 7 and 8 are opened during cleaning, and the valves 8 and 9 are opened during drainage.
[0003]
On the primary side of the hollow fiber membrane module 2, a raw water pipe 11 provided with a valve 5, an exhaust pipe 14 provided with a valve 8, a drain pipe 15 provided with a valve 9, and a membrane breakage detection pipe 16 provided with a valve 10 , respectively. It is attached.
The membrane rupture detector tube 16, is attached to film breakage detection device 3 having a light source 17 and the light receiving element 18. The film breakage detection device 3 is configured to measure the air passing through the film breakage detection tube 16 with the light source 17 and the light receiving element 18.
[0004]
On the secondary side of the hollow fiber membrane module 2, a membrane filtration water pipe 12 provided with a valve 6 and an air pipe 13 provided with a valve 7 are attached.
The compressor 4 communicates with the air pipe 13.
Next, the conventional membrane filtration apparatus 1 configured as described above will be described.
The operation | movement of the conventional membrane filtration apparatus 1 has performed repeatedly the filtration process, the washing | cleaning process, the drain process, the full water process, and the fracture | rupture detection process.
[0005]
The lines through which each water or air flows are as follows.
First, in the filtration process, the raw water is filtered through the path of the raw water pipe 11 → the valve 5 → the hollow fiber membrane module 2 → the valve 6 → the membrane filtered water pipe 12.
Next, in the cleaning process, the cleaning process of the hollow fiber membrane module 2 is performed through the path of the compressor 4 → the air pipe 13 → the valve 7 → the hollow fiber membrane module 2 → the valve 8 → the exhaust pipe 14.
[0006]
Next, in the drain process, the cleaning water used in the cleaning process is drained through the path of the valve 8 → the hollow fiber membrane module 2 → the valve 9 → the drain pipe 15. Here, the valve 8 is opened to allow air to enter during drain drainage.
Next, in a full water process, the process which makes the inside of the hollow fiber membrane module 2 full through the path | route of the raw | natural water pipe | tube 11-> valve 5-> hollow fiber membrane module 2 is performed. Here, the valve 8 is opened to release the air inside the hollow fiber membrane module 2 to the atmosphere.
[0007]
Next, in the break detection step, the break detection process of the hollow fiber membrane module 2 is performed via the path of the air tube 13 → the valve 7 → the hollow fiber membrane module 2 → the valve 10 → the membrane break detection tube 16 → the membrane break detection device 3. Is done.
[Patent Document 1]
JP 11-311596 A [Patent Document 2]
JP 2000-126563 A [Patent Document 3]
JP 2000-342937 A [Patent Document 4]
Japanese Patent Laid-Open No. 2001-269551
[Problems to be solved by the invention]
However, in the conventional membrane filtration device 1 shown in FIG. 5, one membrane breakage detection device 3 is installed for one of the hollow fiber membrane modules 2, so the membrane filtration device 1 is not complicated. It was.
Further, since compressed air is sent to the hollow fiber membrane module 2 by the compressor 4 and the air passing through the membrane breakage detection tube 16 is measured by the light source 17 and the light receiving element 18 inside the membrane breakage detection device 3, There was a risk that the inside of the film breakage detection device 3 would become dirty and malfunction.
[0009]
In order to prevent this malfunction, it was necessary to frequently clean the inside of the film breakage detection device 3.
In Patent Documents 1 to 4, as with the conventional membrane filtration device 1 shown in FIG. 5, it is necessary to install one membrane breakage detection device for one of the hollow fiber membrane modules. There was a problem that became complicated.
[0010]
The present invention has been made to solve such conventional problems, and an object of the present invention is to provide a membrane filtration apparatus capable of easily detecting membrane breakage and an operation method thereof.
[0011]
[Means for Solving the Problems]
The invention according to claim 1 includes a plurality of hollow fiber membrane modules for filtering raw water, a raw water pipe attached to a primary side of the plurality of hollow fiber membrane modules via a valve, and a primary of the plurality of hollow fiber membrane modules. An exhaust pipe attached to the side through a valve, a drain pipe attached to the primary side of the plurality of hollow fiber membrane modules via a valve, and attached to a primary side of the plurality of hollow fiber membrane modules via a valve A membrane breakage detection tube, a water level meter for measuring the rising speed of the water level, and a means for issuing a warning and notifying the membrane breakage when the rising rate is slow or not rising, and contacting the membrane breakage detection tube A membrane rupture detection water tank, a membrane filtration water pipe attached to a secondary side of the plurality of hollow fiber membrane modules via a valve, and an air pipe attached to a secondary side of the plurality of hollow fiber membrane modules via a valve; The air A compressor that communicates with the plurality of hollow fiber membrane modules, only the valves provided in the raw water pipe and the membrane filtration water pipe are opened at the time of filtration by the plurality of hollow fiber membrane modules, and the air at the time of washing the plurality of hollow fiber membrane modules Only the valves provided in the pipe and the exhaust pipe are opened, and compressed air is supplied from the compressor to the secondary side of the plurality of hollow fiber membrane modules through the air pipe, and the plurality of hollow fiber membrane modules When draining after washing, only the valves provided in the exhaust pipe and the drain pipe are opened, and when the plurality of hollow fiber membrane modules are full, only the valves provided in the raw water pipe and the exhaust pipe are opened. When the membrane breakage of the plurality of hollow fiber membrane modules is detected, only the valves provided in the air pipe and the membrane breakage detection pipe are opened, and the multiple pipes from the compressor through the air pipe are opened. The compressed air is supplied to the secondary side of the hollow fiber membrane module, and storing water flowing through the membrane rupture detection tube to the membrane rupture detection water tank, to measure the rate of rise of the water level of said membrane rupture detection aquarium When the degree of increase is slow or does not increase, the plurality of hollow fiber membrane modules are determined to have a membrane breakage .
[0012]
The invention according to claim 2 is the membrane filtration apparatus according to claim 1, wherein the pressure of the compressed air supplied at the time of detecting the membrane breakage of the hollow fiber membrane module is lower than the bubble point. .
The invention according to claim 3 is the membrane filtration device according to claim 1, wherein the membrane breakage detection water tank is an open water tank provided with a drain valve, and only when membrane breakage of the plurality of hollow fiber membrane modules is detected. The drain valve is closed .
[0013]
The invention according to claim 4 is the membrane filtration device according to claim 1, wherein the membrane breakage detection water tank is a sealed water tank provided with a drain valve, and the pressure inside the water tank that varies with the water level; The water level when the pressure on the primary side of the plurality of hollow fiber membrane modules is about to reach an equilibrium state is measured with the water level meter .
The invention according to claim 5 includes a raw water filtration step, a washing step for the plurality of hollow fiber membrane modules, a drain step for the plurality of hollow fiber membrane modules, a water filling step for the plurality of hollow fiber membrane modules, and the plurality of hollows. The membrane filtration device operating method according to claim 1, wherein the membrane breakage detection step of the yarn membrane module is sequentially performed, and in the raw water filtration step, only the valves provided in the raw water tube and the membrane filtration water tube are opened. The raw water is pressurized and fed to the hollow fiber membrane module due to a water level difference between the raw water supply source and the plurality of hollow fiber membrane modules, filtered, and the filtered water is led out through the membrane filtered water pipe, In the cleaning step of the plurality of hollow fiber membrane modules, only the valves provided in the air pipe and the exhaust pipe are opened, and the secondary of the plurality of hollow fiber membrane modules is passed from the compressor through the air pipe. In the drain process of the plurality of hollow fiber membrane modules, only the valves provided in the exhaust pipe and the drain pipe are opened, and the water on the primary side of the plurality of hollow fiber membrane modules is discharged. In the filling process of the plurality of hollow fiber membrane modules, only the valves provided in the raw water pipe and the exhaust pipe are opened, and in the membrane breakage detection process of the plurality of hollow fiber membrane modules, the air pipe and the membrane Only the valve provided on the breakage detection tube is opened, and compressed air is supplied from the compressor to the secondary side of the plurality of hollow fiber membrane modules via the air tube, and flows out via the membrane breakage detection tube. Water is stored in the membrane rupture detection water tank, the rate of rise of the water level of the membrane rupture detection water tank is measured, and when the degree of increase is slow or does not rise, it is determined that there is a membrane rupture of the plurality of hollow fiber membrane modules this is The features.
[0014]
The invention according to claim 6 is the operation method of the membrane filtration device according to claim 5, wherein the pressure of the compressed air supplied to the membrane breakage detecting step of the hollow fiber membrane module is lower than the bubble point. It is characterized by .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 shows a membrane filtration device 50 according to a first embodiment of the present invention (corresponding to claims 1 to 3 ).
The membrane filtration device 50 according to the present embodiment is different from the conventional membrane filtration device 1 shown in FIG. 5 in that a membrane rupture detection water tank 64 is provided in the membrane rupture detection tube 58 .
The membrane filtration device 50 according to the present embodiment includes a plurality of hollow fiber membrane modules 51 that filter raw water. The hollow fiber membrane module 51 is, for example, a low-pressure hollow fiber membrane module containing an external pressure hollow fiber membrane having a pore diameter of about 2 μm.
[0016]
On the primary side 51 a of each hollow fiber membrane module 51, a raw water pipe 52 provided with a valve 53, an exhaust pipe 54 provided with a valve 55, a drain pipe 56 provided with a valve 57, and a membrane break provided with a valve 59. A detection tube 58 is attached.
A membrane filtration water pipe 60 having a valve 61 and an air pipe 62 having a valve 63 are attached to the secondary side 51 b of each hollow fiber membrane module 51.
[0017]
The membrane breakage detection pipe 58 communicates with an open type membrane breakage detection water tank 64 having a water level meter 65 and a valve 66.
The air pipe 62 communicates with a compressor 67 that supplies compressed air.
Next, using the membrane filtration device 50 according to this embodiment thus configured, a raw water filtration step, a plurality of hollow fiber membrane module 51 washing steps, a plurality of hollow fiber membrane module 51 drain steps, a plurality of An operation method for sequentially performing the water filling step of the hollow fiber membrane module 51 and the membrane breakage detection step of the plurality of hollow fiber membrane modules 51 will be described (corresponding to claims 5 to 6 ).
[0018]
First, in the raw water filtration step, only the valves 53 and 61 provided in the raw water pipe 52 and the membrane filtration water pipe 60 are opened, and the other valves 55, 57, 59, and 63 are closed.
The raw water is pressurized and supplied to the primary side 51 a of the hollow fiber membrane module 51 due to the difference in water level between the raw water supply source and the plurality of hollow fiber membrane modules 51, and is filtered through pores vacated on the membrane surface of the hollow fiber membrane module 51. Then, it flows out as filtered water to the secondary side 51 b of the hollow fiber membrane module 51 and is stored in an arbitrary water tank or the like via the membrane filtered water pipe 60.
[0019]
Next, after closing the valve 53 provided in the raw | natural water pipe | tube 52 and the valve 61 provided in the membrane filtration water pipe | tube 60, it transfers to the washing | cleaning process of the some hollow fiber membrane module 51. FIG.
Here, only the valves 63 and 55 provided in the air pipe 62 and the exhaust pipe 54 are opened, compressed air is supplied from the compressor 67 to the secondary side 51b of the hollow fiber membrane module 51 through the air pipe 62, The membrane is backwashed by passing compressed air from the secondary side 51b of the yarn membrane module 51 to the primary side 51a.
[0020]
As described above, in the membrane filtration by the hollow fiber membrane module 51, the filtrate can be obtained by filtering the raw water through the pores vacant on the membrane surface. When the pores are wetted with a liquid such as water and a pressure is applied to the secondary side 51b of the hollow fiber membrane module 51 with air, the water in the pores is pushed out by the air at a certain pressure, and the hollow fiber membrane module 51 Passes through the primary side 51a. This pressure is called a bubble point. The bubble point is about 30 kPa in the case of a low-pressure membrane.
[0021]
Therefore, when a pressure lower than the bubble point is applied to the secondary side 51 b of the hollow fiber membrane module 51, air does not pass through the primary side 51 a of the hollow fiber membrane module 51.
However, when the membrane has a broken portion, air leaks from the broken portion to the primary side 51a of the hollow fiber membrane module 51 even at a pressure lower than the bubble point.
[0022]
The cleaning time is, for example, about 15 seconds.
Using such a function, the plurality of hollow fiber membrane modules 51 are cleaned.
Next, after closing the valve 63, the valve 57 is opened and the process proceeds to the draining process of the plurality of hollow fiber membrane modules 51.
Here, by opening the valve 57, air is introduced into the primary sides 51a of the plurality of hollow fiber membrane modules 51 through the exhaust pipe 54, and the water in the primary sides 51a of the plurality of hollow fiber membrane modules 51 is allowed to flow. Discharged.
[0023]
Next, after closing the valve 57, the valve 53 is opened, and the process proceeds to a water filling process for the plurality of hollow fiber membrane modules 51.
Here, the raw water flows into the plurality of hollow fiber membrane modules 51 through the raw water pipe 52, and the plurality of hollow fiber membrane modules 51 can be filled with the raw water.
Next, after closing the valves 53 and 55, the valves 59 and 63 are opened, and the compressed air is supplied from the compressor 67 to the secondary sides 51 b of the plurality of hollow fiber membrane modules 51. The process proceeds to the film breakage detection step 51.
[0024]
As described above, when a pressure lower than the bubble point is applied to the secondary side 51b of the hollow fiber membrane module 51, air does not pass through the primary side 51a of the hollow fiber membrane module 51. Only water passes through.
However, when there is a breakage point in the membrane, air leaks from the breakage point to the primary side 51a of the hollow fiber membrane module 51 even at a pressure lower than the bubble point, so that both air and water flow through the membrane breakage detection tube 58.
[0025]
For this reason, when the amount of water flowing through the membrane rupture detection tube 58 is different and the water that has permeated the membrane is stored in the membrane rupture detection water tank 64, the water level rising speed is different. Film breakage is detected by measuring the rising speed of the water level with a water level meter 65.
Then, the rising speed of the water level in the membrane rupture detection water tank 64 is measured by the water level meter 65. The result is shown in FIG. When the rate of increase is slow or does not increase, an alarm is issued so that film breakage can be confirmed.
[0026]
The valve 66 provided in the membrane rupture detection water tank 64 is closed only during the membrane rupture detection step of the plurality of hollow fiber membrane modules 51.
As described above, according to the present embodiment, it is only necessary to install one membrane breakage detection water tank 64 for a plurality of hollow fiber membrane modules 51, which is simpler than conventional membrane filtration devices.
[0027]
Further, by sending air to the secondary side 51b of the plurality of hollow fiber membrane modules 51 using the cleaning compressor 67, at the time of breakage, the rise in the water level of the membrane breakage detection water tank 64 is slower than usual. Or, since it does not rise, it is possible to check for breakage, and it is possible to cope with a large number of modules.
Further, since no light receiving element is used for detecting breakage, malfunction due to poor cleaning or the like does not occur.
[0028]
The cleaning is to be done periodically at a constant cycle, it is checked regularly broken.
FIG. 3 shows a membrane filtration device 70 according to a second embodiment of the present invention (corresponding to claims 1 to 2 and claim 4 ).
The membrane filtration device 70 according to this embodiment is different from the membrane filtration device 50 according to the first embodiment in that the membrane rupture detection water tank 64 is a sealed type.
[0029]
In the membrane filtration device 70 according to the present embodiment, as with the membrane filtration device 50 according to the first embodiment, when a pressure lower than the bubble point is applied to the secondary side 51b of the plurality of hollow fiber membrane modules 51, a plurality of Since no air passes through the primary side 51 a of the hollow fiber membrane module 51, only water passes through the membrane breakage detection tube 58.
At this time, as the water level rises, the pressure inside the membrane rupture detection water tank 64 rises, reaches an equilibrium state with the pressure of the supplied air, and the passage of water stops.
[0030]
If there are breaks in the membranes of the plurality of hollow fiber membrane modules 51, air leaks from the breaks to the primary side 51a of the plurality of hollow fiber membrane modules 51 even at a pressure lower than the bubble point. Both air and water flow.
For this reason, the water level when the internal pressure of the membrane rupture detection water tank 64 rises and is in equilibrium with the pressure of the air sent from the air pipe 62 is as shown in FIG. Lower than the case.
[0031]
A film break is detected by measuring the water level at this time with a water level meter 65. Alternatively, the rising speed of the water level is measured with a water level meter 65. Alternatively, measure both the water level and the rising speed of the water level.
Also in the present embodiment, it is possible to achieve the same effects as the membrane filtration device 50 according to the first embodiment.
[0032]
【The invention's effect】
According to the present invention, it is possible to detect membrane breakage of a plurality of hollow fiber membrane modules only by installing one membrane breakage detection water tank for the plurality of hollow fiber membrane modules.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a membrane filtration device according to a first embodiment of the present invention.
FIG. 2 is a graph showing membrane breakage detection in the membrane filtration device according to the first embodiment of the present invention.
FIG. 3 is an explanatory view showing a membrane filtration device according to a second embodiment of the present invention.
FIG. 4 is a graph showing membrane breakage detection in the membrane filtration device according to the second embodiment of the present invention.
FIG. 5 is an explanatory view showing a conventional membrane filtration device.
[Explanation of symbols]
50, 70 Membrane filtration device 51 Hollow fiber membrane module 51a Primary side 51b of hollow fiber membrane module 51 Secondary side 52 of hollow fiber membrane module 51 Raw water pipe 53, 55, 57, 59, 61, 63, 66 Valve 54 Exhaust pipe 56 Drainage pipe 58 Membrane breakage detection pipe 60 Membrane filtration water pipe 62 Air pipe 64 Membrane breakage detection water tank 65 Water level gauge 67 Compressor

Claims

A plurality of hollow fiber membrane modules for filtering raw water;
A raw water pipe attached to a primary side of the plurality of hollow fiber membrane modules via a valve;
An exhaust pipe attached to a primary side of the plurality of hollow fiber membrane modules via a valve;
A drain pipe attached to a primary side of the plurality of hollow fiber membrane modules via a valve;
A membrane breakage detector tube attached to a primary side of the plurality of hollow fiber membrane modules via a valve;
A water level meter that measures the rate of rise of the water level, and when the rate of rise is slow or does not rise, it comprises means for issuing a warning and notifying membrane breakage, and a membrane breakage detection water tank that communicates with the membrane breakage detector tube,
A membrane filtration water pipe attached to the secondary side of the plurality of hollow fiber membrane modules via a valve;
An air pipe attached to the secondary side of the plurality of hollow fiber membrane modules via a valve;
A compressor communicating with the air pipe,
During filtration by the plurality of hollow fiber membrane modules, only the valves provided in the raw water pipe and the membrane filtration water pipe are opened,
When cleaning the plurality of hollow fiber membrane modules, only the valves provided in the air pipe and the exhaust pipe are opened, and from the compressor to the secondary side of the plurality of hollow fiber membrane modules through the air pipe Supply compressed air,
During drainage after washing the plurality of hollow fiber membrane modules, only the valves provided in the exhaust pipe and the drain pipe are opened,
When the plurality of hollow fiber membrane modules are full of water, only the valves provided in the raw water pipe and the exhaust pipe are opened,
At the time of detecting membrane breakage of the plurality of hollow fiber membrane modules, only the valves provided in the air pipe and the membrane breakage detection pipe are opened, and from the compressor via the air pipe, the plurality of hollow fiber membrane modules. Compressed air is supplied to the secondary side, the water flowing out through the membrane rupture detection tube is stored in the membrane rupture detection water tank, the rising speed of the water level in the membrane rupture detection water tank is measured, and the degree of increase is slow Alternatively , the membrane filtration device is configured to determine that the plurality of hollow fiber membrane modules have a membrane rupture when they do not rise .

The membrane filtration device according to claim 1,
The membrane filtration device according to claim 1, wherein the pressure of the compressed air supplied at the time of detecting the membrane breakage of the hollow fiber membrane module is lower than a bubble point .

The membrane filtration device according to claim 1,
The membrane filtration detecting water tank is an open-type water tank equipped with a drain valve, and the drain valve is closed only when a membrane break of the plurality of hollow fiber membrane modules is detected .

The membrane filtration device according to claim 1,
The membrane rupture detection water tank is a sealed water tank equipped with a drain valve, and the pressure inside the water tank, which fluctuates with the water level, and the pressure on the primary side of the plurality of hollow fiber membrane modules are in an equilibrium state. A membrane filtration device characterized by measuring a water level when attempting to be measured with the water level gauge .

Raw water filtration step, washing step of the plurality of hollow fiber membrane modules, draining step of the plurality of hollow fiber membrane modules, filling step of the plurality of hollow fiber membrane modules, and membrane breakage detection step of the plurality of hollow fiber membrane modules The operation method of the membrane filtration device according to claim 1, wherein
In the raw water filtration step, only the valves provided in the raw water pipe and the membrane filtration water pipe are opened, and the raw water is supplied to the hollow fiber membrane module by the difference in water level between the raw water supply source and the plurality of hollow fiber membrane modules. Pressurized water and filtered water, and the filtered water is led out through the membrane filtered water pipe,
In the washing step of the plurality of hollow fiber membrane modules, only the valves provided in the air pipe and the exhaust pipe are opened, and the secondary side of the plurality of hollow fiber membrane modules is passed from the compressor through the air pipe. Supply compressed air to
In the drain process of the plurality of hollow fiber membrane modules, only the valves provided in the exhaust pipe and the drain pipe are opened, and the water on the primary side of the plurality of hollow fiber membrane modules is discharged,
In the filling process of the plurality of hollow fiber membrane modules, only the valves provided in the raw water pipe and the exhaust pipe are opened,
In the membrane breakage detecting step of the plurality of hollow fiber membrane modules, only the valves provided in the air pipe and the membrane breakage detection pipe are opened, and the plurality of hollow fiber membrane modules are passed from the compressor via the air pipe. Compressed air is supplied to the secondary side of the gas, the water flowing out through the membrane breakage detection tube is stored in the membrane breakage detection water tank, the rising speed of the water level of the film breakage detection water tank is measured, and the degree of increase is A method of operating a membrane filtration device , characterized in that, when slow or not rising, it is determined that there is a membrane breakage of the plurality of hollow fiber membrane modules .

In the operation method of the membrane filtration device according to claim 5,
The method for operating a membrane filtration device, wherein the pressure of the compressed air supplied to the membrane breakage detecting step of the hollow fiber membrane module is lower than a bubble point .