JP2008207165A - Air diffusion plate, air diffusion device, and clogging removing method of air diffusion plate - Google Patents

Air diffusion plate, air diffusion device, and clogging removing method of air diffusion plate Download PDF

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JP2008207165A
JP2008207165A JP2007133127A JP2007133127A JP2008207165A JP 2008207165 A JP2008207165 A JP 2008207165A JP 2007133127 A JP2007133127 A JP 2007133127A JP 2007133127 A JP2007133127 A JP 2007133127A JP 2008207165 A JP2008207165 A JP 2008207165A
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diffuser plate
diffuser
casing
air
pressure loss
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JP4743162B2 (en
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Akira Kunugi
亮 功刀
Takeshi Tsuji
猛志 辻
Satoru Udagawa
悟 宇田川
Keisuke Nakahara
啓介 中原
Yukihiko Okamoto
幸彦 岡本
Takashi Miura
崇 三浦
Kazusato Oohashi
一聡 大橋
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JFE Engineering Corp
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JFE Engineering Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

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Abstract

<P>PROBLEM TO BE SOLVED: To provide an air diffusion plate forming uniform and fine bubbles, suppressing coalescence of bubbles, and providing high oxygen movement efficiency. <P>SOLUTION: The air diffusion plate comprises a thin plate having multiple apertures and diffuses bubbles into liquid through the apertures. The aperture has a rectangular shape with short sides and long sides facing each other. Among spaces in the short side directions, the length of the widest part is 0.03-0.15 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、散気板、散気装置、および散気板の目詰まり除去方法に関する。   The present invention relates to a diffuser plate, an air diffuser, and a method for removing clogging of the diffuser plate.

気液接触により気相から液相へ物質を移動する技術、特に、好気性生物反応を利用した水処理槽へ酸素を移動するにあたって、散気板が用いられている。酸素移動の効率を高めるために、種々の散気板および散気装置が提案されている。   A diffuser plate is used in transferring oxygen from a gas phase to a liquid phase by gas-liquid contact, particularly in transferring oxygen to a water treatment tank using an aerobic biological reaction. Various diffusers and diffusers have been proposed to increase the efficiency of oxygen transfer.

例えば、圧縮空気が供給されるホルダーに多数の小孔を備えた合成樹脂または合成ゴム製のメンブレンを装着したメンブレン散気装置の改良が提案されている（例えば、特許文献１参照）。かかるメンブレン散気装置においては、給気によりメンブレンを膨らませて、閉じている小孔を押し広げることによって発泡させる。したがって、圧力損失が大きいという問題があった。   For example, an improvement of a membrane air diffuser in which a synthetic resin or synthetic rubber membrane having a large number of small holes is attached to a holder to which compressed air is supplied has been proposed (see, for example, Patent Document 1). In such a membrane diffuser, the membrane is inflated by supplying air, and foamed by expanding the closed small holes. Therefore, there is a problem that the pressure loss is large.

また、微細なスリット状の孔を有する金属製の板から発泡させる散気装置が提案されている（例えば、特許文献２参照）。これにおいては、圧力損失が小さく、微細な気泡を発生させることができることから、高い酸素移動効率が得られる。   In addition, an air diffuser that foams from a metal plate having fine slit-like holes has been proposed (see, for example, Patent Document 2). In this, since the pressure loss is small and fine bubbles can be generated, high oxygen transfer efficiency can be obtained.

しかしながら、散気装置に供給される空気の流量によっては、発泡が断続的になる等の現象が発生することがある。この場合には、生成する気泡の大きさや間隔が著しく不均一となって気泡同士が合一しやすくなり、結果として酸素移動効率の低下につながる。また、複数の散気装置を一本の配管に接続した場合には、スリット状の孔の圧力損失が小さいことに起因して次のような現象が生じる。具体的には、わずかでも圧力損失の小さい散気装置に空気流量が集中して、必ずしも全ての散気装置を有効に利用することができず、散気面積が減少してしまう。さらに、気泡の大きさが不均一になって合一しやすく、酸素移動効率が下がることがある。   However, depending on the flow rate of the air supplied to the air diffuser, a phenomenon such as intermittent foaming may occur. In this case, the size and interval of the bubbles to be generated are extremely non-uniform and the bubbles are likely to be united, resulting in a decrease in oxygen transfer efficiency. Further, when a plurality of air diffusers are connected to one pipe, the following phenomenon occurs due to the small pressure loss of the slit-shaped hole. Specifically, the air flow rate is concentrated on an air diffuser with a small pressure loss, and not all the air diffusers can be used effectively, and the air diffused area is reduced. Furthermore, the size of the bubbles becomes non-uniform and can easily be united, which can reduce the oxygen transfer efficiency.

また、散気板が下水や工業排水の好気性生物反応槽に浸漬して用いられる場合には、被処理水に含まれる微生物が孔の周辺に徐々に付着することによって、孔の目詰まりが生じる。その結果、発泡が不均一となって酸素移動効率が低下したり、圧力損失が上昇して散気板に必要な量の送風ができなくなるなどの問題があった。
特開２００３−３２０３８８号公報 特開２００６−６１８１７号公報 In addition, when the diffuser plate is immersed in an aerobic biological reaction tank for sewage or industrial wastewater, microorganisms contained in the water to be treated gradually adhere to the periphery of the hole, thereby clogging the hole. Arise. As a result, there are problems such that foaming becomes non-uniform and oxygen transfer efficiency is reduced, or pressure loss is increased and the amount of air necessary for the diffuser plate cannot be blown.
JP 2003-320388 A JP 2006-61817 A

本発明は、上記の問題点を解決し、均一で微細な気泡を生成でき、しかも気泡同士の合一を抑制して、高い酸素移動効率の得られる散気板を提供することを目的とする。また本発明は、複数の散気装置を一本の配管に接続した場合でも、各散気装置の空気流量を等分化できるとともに、ケーシングへ内部の水の逆流を防止する散気装置を提供することを目的とする。さらに本発明は、散気板の目詰まりを除去する方法を提供することを目的とする。   SUMMARY OF THE INVENTION An object of the present invention is to provide a diffuser plate that solves the above-described problems, can generate uniform and fine bubbles, and suppresses coalescence of the bubbles, thereby obtaining high oxygen transfer efficiency. . The present invention also provides an air diffuser capable of equally dividing the air flow rate of each air diffuser even when a plurality of air diffusers are connected to a single pipe and preventing the backflow of water inside the casing. For the purpose. A further object of the present invention is to provide a method for removing clogging of the diffuser plate.

本発明にかかる散気板は、複数の開孔を有する薄板からなり、前記開孔を通して液体中に気泡を分散させる散気板であって、前記開孔は、向かい合う短辺と長辺とにより構成された四角形形状を有し、前記短辺方向の間隙のうち、最も広い部分の長さは０．０３ｍｍ〜０．１５ｍｍであることを特徴とする。   The diffuser plate according to the present invention is a diffuser plate that is made of a thin plate having a plurality of apertures, and disperses bubbles in the liquid through the apertures, and the aperture is formed by a short side and a long side facing each other. It has a configured rectangular shape, and the length of the widest portion of the gap in the short side direction is 0.03 mm to 0.15 mm.

本発明にかかる散気装置は、ケーシングと、散気板固定枠により前記ケーシングに固定された散気板と、前記ケーシングに連通した送気管と具備し、前記送気管と前記ケーシングとの間、または前記ケーシングの内部に、逆止弁が装着されていることを特徴とする。   An air diffuser according to the present invention comprises a casing, an air diffuser plate fixed to the casing by an air diffuser plate fixing frame, an air supply pipe communicating with the casing, and between the air supply pipe and the casing, Alternatively, a check valve is mounted inside the casing.

本発明にかかる散気板の目詰まり除去方法は、ケーシングと、散気板固定枠により前記ケーシングに固定された散気板と、前記ケーシングに連通した送気管とを具備する散気装置における散気板の目詰まりを除去する方法であって、前記送気管内に薬剤を噴霧することを特徴とする。   A method for removing clogging of a diffuser plate according to the present invention includes a diffuser in a diffuser comprising a casing, a diffuser plate fixed to the casing by a diffuser plate fixing frame, and an air supply pipe communicating with the casing. A method for removing clogging of an air plate, wherein the medicine is sprayed into the air supply tube.

本発明によれば、均一で微細な気泡を生成でき、しかも気泡同士の合一を抑制して、高い酸素移動効率の得られる散気板が提供される。また本発明によれば、複数の散気装置を一本の配管に接続した場合でも、各散気装置の空気流量を等分化できるとともに、ケーシングへ内部の水の逆流を防止する散気装置が提供される。さらに本発明によれば、散気板の目詰まりを除去する方法が提供される。   ADVANTAGE OF THE INVENTION According to this invention, the diffuser plate which can produce | generate uniform and fine bubble, and also suppresses coalescence of bubbles and obtains high oxygen transfer efficiency is provided. Further, according to the present invention, there is provided an air diffuser capable of equalizing the air flow rate of each air diffuser even when a plurality of air diffusers are connected to a single pipe and preventing the backflow of water inside the casing. Provided. Furthermore, according to this invention, the method of removing the clogging of a diffuser plate is provided.

以下、図面を参照して本発明を詳細に説明する。   Hereinafter, the present invention will be described in detail with reference to the drawings.

図１は、本発明の一実施例にかかる散気装置の断面図である。図示するように、散気装置１０においては、散気板１が散気板固定枠２によってケーシング４の上部に装着されており、このケーシング４は、送気管３と連通している。ケーシング４と送気管３との間には、逆止弁１１が設けられている。なお、図１中、参照符号１３は散気板１とケーシング４との間の間隙を示す。   FIG. 1 is a cross-sectional view of an air diffuser according to an embodiment of the present invention. As shown in the figure, in the diffuser 10, the diffuser plate 1 is mounted on the upper portion of the casing 4 by the diffuser plate fixing frame 2, and the casing 4 communicates with the air supply pipe 3. A check valve 11 is provided between the casing 4 and the air supply pipe 3. In FIG. 1, reference numeral 13 indicates a gap between the diffuser plate 1 and the casing 4.

図２には、かかる散気装置１０の平面図を示す。図示するように、散気板１は、複数の開孔（スリット）を有する薄板から構成される。薄板の材質は、通常、ステンレス、チタン、アルミ、銅またはそれらを主成分とする合金である。特に、表面に均質な酸化皮膜を形成しやすく、均一な発泡状態を得やすいことから、ステンレスまたはチタンが好ましく用いられる。散気板１の形状は特に限定されず、任意に決定することができる。曝気槽の断面積を有効に利用できることから、長方形または正方形が好ましい。   FIG. 2 shows a plan view of such an air diffuser 10. As shown in the figure, the diffuser plate 1 is composed of a thin plate having a plurality of openings (slits). The material of the thin plate is usually stainless steel, titanium, aluminum, copper or an alloy containing them as a main component. In particular, stainless steel or titanium is preferably used because it is easy to form a uniform oxide film on the surface and easily obtain a uniform foamed state. The shape of the diffuser plate 1 is not particularly limited and can be arbitrarily determined. Since the cross-sectional area of the aeration tank can be used effectively, a rectangle or a square is preferable.

下水や工業排水などのように微生物を多く含んだ被処理水に適用される場合、散気板１の開孔５内部には、微生物が繁殖して目詰まりが起こりやすくなる。微生物の繁殖を抑制する物質を含む材料を用いて薄板を作製することによって、こうした問題を低減することができる。   When applied to treated water containing a large amount of microorganisms, such as sewage and industrial wastewater, microorganisms propagate in the openings 5 of the diffuser plate 1 and clogging is likely to occur. Such a problem can be reduced by producing a thin plate using a material containing a substance that suppresses the growth of microorganisms.

薄板の微生物の繁殖を抑制する物質を含む材料としては、微量で微生物の繁殖を抑制する効果が高く、効果の持続性が高い銀を含んだ材料が好ましく用いられる。   As a material containing a substance that suppresses the growth of microorganisms in a thin plate, a material containing silver that has a high effect of suppressing the growth of microorganisms in a small amount and has a long-lasting effect is preferably used.

図２に示した散気板１における領域ｃの拡大図を、図３に示す。散気板１には、図示するように、複数の開孔５が設けられている。開孔５の形状は、向かい合う短辺６と長辺７とから構成される四角形形状である。図示される開孔５は矩形状であるが、必ずしも辺同士が平行で正確な矩形状に限定されるわけではない。また、開孔５は、短辺方向のピッチ８および長辺方向のピッチ９で配置されている。短辺方向のピッチ８および長辺方向のピッチ９は、通常、２〜４ｍｍ程度である。この範囲のピッチで開孔５が設けられていれば、生成する気泡間の距離を確保することができるので気泡合一が起こりにくく、高い酸素移動効率が得られる。   FIG. 3 shows an enlarged view of the region c in the diffuser plate 1 shown in FIG. As shown in the figure, the diffuser plate 1 is provided with a plurality of apertures 5. The shape of the opening 5 is a quadrangular shape composed of a short side 6 and a long side 7 facing each other. The illustrated opening 5 is rectangular, but is not necessarily limited to an exact rectangular shape with parallel sides. The openings 5 are arranged with a pitch 8 in the short side direction and a pitch 9 in the long side direction. The pitch 8 in the short side direction and the pitch 9 in the long side direction are usually about 2 to 4 mm. If the apertures 5 are provided at a pitch in this range, the distance between the generated bubbles can be secured, so that bubble coalescence hardly occurs and high oxygen transfer efficiency is obtained.

開孔５の短辺６が小さいほど生成する気泡は微細化する傾向にあるものの、圧力損失も増大する。一方、開孔５の短辺６が大きくなると圧力損失は小さくなるが、生成する気泡は粗大化する。本発明者らは、開孔５の短辺６の長さを所定の範囲内に規定することによって、圧力損失と気泡の平均径との両方を適正な範囲に維持することが可能となることを見出した。   As the short side 6 of the opening 5 is smaller, the generated bubbles tend to become finer, but the pressure loss also increases. On the other hand, when the short side 6 of the opening 5 becomes large, the pressure loss becomes small, but the generated bubbles become coarse. By specifying the length of the short side 6 of the opening 5 within a predetermined range, the present inventors can maintain both the pressure loss and the average diameter of the bubbles in an appropriate range. I found.

図４に、散気板面積当たり送気量２０Ｎｍ3/ｈ／ｍ2での平均気泡径および散気板の圧力損失の測定例を示す。平均気泡径は、生成直後の気泡を写真撮影し、画像処理することにより求めた。また、散気板の圧力損失は、ケーシング４内部に取り付けた圧力センサーにより測定して求めた。 FIG. 4 shows a measurement example of the average bubble diameter and the pressure loss of the diffuser plate at an air supply rate of 20 Nm 3 / h / m 2 per diffuser plate area. The average bubble diameter was determined by taking a picture of the bubble immediately after generation and processing the image. Further, the pressure loss of the diffuser plate was determined by measuring with a pressure sensor attached inside the casing 4.

図４のグラフに示されるように、開孔５の短辺６の長さが大きくなると、気泡の平均径は増大し、散気板の圧力損失は減少する。具体的には、開孔５の短辺６が０．１５ｍｍを越えると、生成気泡が急激に粗大化する。気泡径が１．０ｍｍを越えると、気泡が真球から楕円状になりやすく、上昇中に軌道が蛇行して接触や合一が生じやすくなる。こうした不都合を避けるため、気泡の平均径は１．０ｍｍ以下であることが好ましく、０．７ｍｍ以下であることがより好ましい。   As shown in the graph of FIG. 4, when the length of the short side 6 of the opening 5 increases, the average diameter of the bubbles increases and the pressure loss of the diffuser plate decreases. Specifically, when the short side 6 of the opening 5 exceeds 0.15 mm, the generated bubbles are rapidly coarsened. When the bubble diameter exceeds 1.0 mm, the bubble tends to become an ellipse from a true sphere, and the trajectory meanders during the rise, and contact and coalescence are likely to occur. In order to avoid such inconvenience, the average diameter of the bubbles is preferably 1.0 mm or less, and more preferably 0.7 mm or less.

一方、開孔５の短辺６が０．０３ｍｍ未満になると、圧力損失が５００ｍｍＡｑ以上となる。送気ブロワの能力に依るが、散気装置を設置する水深を浅くする必要が生じる。酸素移動効率が低下するという不都合を避けるために、圧力損失は、５００ｍｍＡｑ未満であることが望まれる。圧力損失は、４００ｍｍＡｑ未満であることがより好ましい。   On the other hand, when the short side 6 of the opening 5 is less than 0.03 mm, the pressure loss is 500 mmAq or more. Depending on the capacity of the air blower, it is necessary to reduce the depth of water in which the air diffuser is installed. In order to avoid the disadvantage that the oxygen transfer efficiency is reduced, the pressure loss is desirably less than 500 mmAq. More preferably, the pressure loss is less than 400 mmAq.

気泡の平均径と散気板の圧力損失との両方を適正な範囲に維持するためには、開孔５の短辺６は０．０３ｍｍ以上０．１ｍｍ以下が好ましい。特に、０．０４ｍｍ以上０．０６ｍｍ以下の範囲がより好ましい。   In order to maintain both the average diameter of the bubbles and the pressure loss of the diffuser plate in an appropriate range, the short side 6 of the opening 5 is preferably 0.03 mm or more and 0.1 mm or less. In particular, the range of 0.04 mm or more and 0.06 mm or less is more preferable.

さらに本発明者らは、散気板１における開孔５の総面積の割合、すなわち開孔面積率にも、最適な範囲が存在することを見出した。開孔面積率が小さすぎる場合には、一つの開孔当たりの空気流量が大きくなるため、開孔を通過する気泡の流れはジェット状となる。その結果、微細な気泡は生成しにくくなって、酸素移動効率が低下する。一方、開孔面積率が大きすぎる場合には、気泡の発泡量に対して送気管３からの空気の供給が追いつかないために、発泡が間欠的となる。その結果、発生する気泡の大きさに加えて、気泡間の距離が不均一になり、さらには、気泡が合一して粗大化しやすくなる。   Furthermore, the present inventors have found that there is an optimum range for the ratio of the total area of the apertures 5 in the diffuser plate 1, that is, the aperture area ratio. When the aperture area ratio is too small, the air flow rate per aperture is increased, and the flow of bubbles passing through the aperture becomes a jet. As a result, fine bubbles are not easily generated, and the oxygen transfer efficiency is lowered. On the other hand, when the opening area ratio is too large, the supply of air from the air supply pipe 3 cannot catch up with the amount of foamed bubbles, and foaming is intermittent. As a result, in addition to the size of the generated bubbles, the distance between the bubbles becomes non-uniform, and the bubbles tend to coalesce and become coarse.

図５に、散気板面積当たり送気量２０Ｎｍ3／ｈ／ｍ2での酸素移動効率の測定例を示す。ここで酸素移動効率は、水温２０℃、散気水深４ｍの換算値であり、（社）日本下水道協会発行の「下水試験法」等に記載の方法により測定した。３２％以上の酸素移動効率が得られれば、メンブレン型等の高性能散気装置と比較して、送風のためのエネルギーを２割以上削減することができる。０．０５％〜１．０％の範囲に開孔面積率を規定することによって、これを達成することができることが、図５からわかる。 FIG. 5 shows a measurement example of the oxygen transfer efficiency at an air supply rate of 20 Nm 3 / h / m 2 per diffuser plate area. Here, the oxygen transfer efficiency is a converted value of a water temperature of 20 ° C. and a diffused water depth of 4 m, and was measured by the method described in “Sewage Test Method” published by Japan Sewerage Association. If an oxygen transfer efficiency of 32% or more is obtained, the energy for blowing air can be reduced by 20% or more compared to a high performance air diffuser such as a membrane type. It can be seen from FIG. 5 that this can be achieved by defining the open area ratio in the range of 0.05% to 1.0%.

なお、図１に示した散気装置１０は、通常、複数個を接続して用いられる。一般的に水処理装置においては、散気装置と比較して処理槽のスケールが大きいためであり、こうした散気装置の例を図６に示す。図示するように、複数の散気装置１０は、送気管３が元管１２に接続されることによって連通している。このため、それぞれの散気装置１０における圧力損失にわずかでも差があると、圧力損失の小さい散気装置に空気の流量が偏ってしまう。この場合には、必ずしも全ての散気装置を有効に利用することができず、散気面積が減少してしまう。さらに、気泡の大きさが不均一になって合一しやすく、酸素移動効率が低下するという問題も生じる。   In addition, the diffuser 10 shown in FIG. 1 is normally used by connecting a plurality. This is because the scale of the treatment tank is generally larger in the water treatment apparatus than in the aeration apparatus, and an example of such an aeration apparatus is shown in FIG. As shown in the drawing, the plurality of air diffusers 10 communicate with each other by connecting the air supply pipe 3 to the main pipe 12. For this reason, if there is even a slight difference in pressure loss in each air diffuser 10, the air flow rate is biased toward the air diffuser having a small pressure loss. In this case, not all the diffusers can be used effectively, and the diffused area is reduced. Furthermore, the size of the bubbles becomes non-uniform so that they can be easily united and the oxygen transfer efficiency is lowered.

本発明者らは、１ｋＰａ〜２ｋＰａ程度の圧力損失を、各散気装置１０の送気管３とケーシング４との間に設置することによって、こうした空気の流量の偏りを防止できることを見出した。図示するように、本実施例においては、逆止弁１１に圧力損失をもたせ、かつケーシング４になるべく近い位置に逆止弁１１を設置する。これによって、各散気装置１０の圧力バランスを均等化して流量の偏りを抑制することが可能となる。さらに、散気停止時の逆流を防止する効果が得られる。   The present inventors have found that such a deviation in the air flow rate can be prevented by installing a pressure loss of about 1 kPa to 2 kPa between the air supply pipe 3 and the casing 4 of each air diffuser 10. As shown in the figure, in this embodiment, the check valve 11 is given pressure loss, and the check valve 11 is installed at a position as close as possible to the casing 4. This makes it possible to equalize the pressure balance of each air diffuser 10 and suppress the flow rate deviation. Furthermore, the effect of preventing the backflow when the aeration is stopped is obtained.

なお、図示する例においては、逆止弁１１は、送気管３とケーシング４との間に設けられているが、逆止弁１１の配置場所はこれに限定されるものではない。逆止弁１１は、ケーシング４の内部の流入口付近に取り付けてもよく、この場合も、同様の効果を得ることができる。   In the illustrated example, the check valve 11 is provided between the air supply pipe 3 and the casing 4, but the location of the check valve 11 is not limited to this. The check valve 11 may be attached in the vicinity of the inflow port inside the casing 4, and in this case, the same effect can be obtained.

上述したとおり、開孔の短辺の長さを所定の範囲内に規定することによって、圧力損失と気泡の平均径との両方を適正な範囲に維持することを可能とした。本発明者らは、開孔５の長辺７の長さに関しても、次のような知見を得た。すなわち、開孔５の長辺７は、長いほど加工が容易であるものの、開孔５内に被処理水が浸入しやすいので目詰まりを起こしやすくなる。一方、開孔５の長辺７が小さくなると、短辺の加工精度を維持することが困難となって不均一な発泡が生じやすくなる。   As described above, by defining the length of the short side of the aperture within a predetermined range, it is possible to maintain both the pressure loss and the average diameter of the bubbles in an appropriate range. The present inventors have also obtained the following knowledge regarding the length of the long side 7 of the opening 5. That is, the longer the long side 7 of the opening 5 is, the easier it is to process. However, since the water to be treated enters the opening 5 easily, clogging is likely to occur. On the other hand, when the long side 7 of the opening 5 is small, it is difficult to maintain the processing accuracy of the short side, and non-uniform foaming is likely to occur.

長辺の長さの適正範囲を得るために、開孔５の長辺７を０．１ｍｍから２．５ｍｍの間で種々変更して、６種類の散気板を作製した。いずれの散気板も、開孔５の短辺６は０．０４ｍｍとし、散気板の厚さは０．３ｍｍとした。   In order to obtain an appropriate range of the long side length, the long side 7 of the opening 5 was variously changed between 0.1 mm and 2.5 mm, and six types of diffuser plates were produced. In each diffuser plate, the short side 6 of the opening 5 was 0.04 mm, and the thickness of the diffuser plate was 0.3 mm.

各散気板を下水処理槽中に設置し、散気板面積当たりの散気量３０Ｎｍ3／ｈ／ｍ2で散気して圧力損失を調べた。散気板の圧力損失を算出するに当たっては、まず、送気管３に取り付けたマノメータによる送風圧力の測定値を求めた。この測定値から、散気板設置位置の静水圧と、別途測定した逆止弁の圧力損失とを差し引いて、圧力損失とした。 Each diffuser plate was installed in a sewage treatment tank and diffused at an diffuser amount of 30 Nm 3 / h / m 2 per diffuser plate area, and the pressure loss was examined. In calculating the pressure loss of the diffuser plate, first, the measured value of the blowing pressure by a manometer attached to the air supply pipe 3 was obtained. From this measurement value, the hydrostatic pressure at the diffuser plate installation position and the pressure loss of the check valve separately measured were subtracted to obtain the pressure loss.

設置当日を起点とした圧力損失上昇値を、図７のグラフに示す。なお、長辺が０．１ｍｍ未満の開孔の場合には、短辺を均一な大きさに加工することが困難となって、各開孔の短辺６にばらつきが生じた。これに起因して、散気板１から安定した発泡を得ることができなかった。   The graph of FIG. 7 shows the pressure loss increase value starting from the installation day. In addition, in the case of an opening having a long side of less than 0.1 mm, it became difficult to process the short side into a uniform size, and the short side 6 of each opening varied. Due to this, stable foaming could not be obtained from the diffuser plate 1.

図７のグラフに示されるように、長辺７が１．５ｍｍ以下の場合には、６０日経過後でも、圧力損失の上昇は１００〜２００ｍｍＡｑ程度に抑えられている。これに対して、開孔５の長辺７が１．５ｍｍを越えると、短期間で圧力損失が著しく上昇してしまう。具体的には、長辺７が２ｍｍの場合には、２８日後には、圧力損失の上昇値は２４０ｍｍＡｑを越え、２．５ｍｍの場合には、わずか２１日で圧力損失の上昇値は５６０ｍｍＡｑにも達している。   As shown in the graph of FIG. 7, when the long side 7 is 1.5 mm or less, the increase in pressure loss is suppressed to about 100 to 200 mmAq even after 60 days. On the other hand, when the long side 7 of the opening 5 exceeds 1.5 mm, the pressure loss is remarkably increased in a short period. Specifically, when the long side 7 is 2 mm, the increase in pressure loss exceeds 240 mmAq after 28 days, and in the case of 2.5 mm, the increase in pressure loss reaches 560 mmAq in just 21 days. Has also reached.

したがって、圧力損失の上昇を１００〜２００ｍｍＡｑ程度に抑制するためには、開孔５の長辺７は、０．１〜１．５ｍｍの範囲内とすることが望まれる。   Therefore, in order to suppress the increase in pressure loss to about 100 to 200 mmAq, it is desirable that the long side 7 of the opening 5 be in the range of 0.1 to 1.5 mm.

さらに本発明者らは散気板の厚さにも着目し、この厚さを０．１ｍｍから１ｍｍの間で種々変更して６種類の散気板を作製した。いずれの散気板も、散気板の開孔５の短辺６は０．０４ｍｍ、長辺７は１．０ｍｍとした。   Furthermore, the present inventors paid attention also to the thickness of the diffuser plate, and produced six types of diffuser plates by variously changing the thickness between 0.1 mm and 1 mm. In any of the diffuser plates, the short side 6 of the aperture 5 of the diffuser plate was 0.04 mm, and the long side 7 was 1.0 mm.

各散気板を下水処理槽中に設置して、前述と同様の条件で圧力損失の増加量を測定した。その結果を図８に示す。なお、散気板１の厚さが０．１ｍｍ未満の場合には、開孔５の短辺６を均一な大きさに加工することが困難となって、各孔の短辺６にばらつきが生じ、散気板１から均一な発泡を得ることができなかった。   Each diffuser plate was installed in a sewage treatment tank, and the amount of increase in pressure loss was measured under the same conditions as described above. The result is shown in FIG. In addition, when the thickness of the diffuser plate 1 is less than 0.1 mm, it becomes difficult to process the short side 6 of the opening 5 into a uniform size, and the short side 6 of each hole varies. As a result, uniform foaming could not be obtained from the diffuser plate 1.

図８のグラフに示されるように、散気板の厚さが０．５ｍｍ以下の場合には、６０日経過後でも圧力損失の上昇は１００〜２００ｍｍＡｑ程度に抑えられている。これに対して、散気板の厚さが０．５ｍｍを越えると、短期間で圧力損失が著しく上昇してしまう。具体的には、散気板の厚さが０．８ｍｍの場合には、２８日後には、圧力損失の上昇値は２５０ｍｍＡｑを越え、１ｍｍの場合には、わずか２１日で圧力損失の上昇値は３８０ｍｍＡｑにも達している。   As shown in the graph of FIG. 8, when the thickness of the diffuser plate is 0.5 mm or less, the increase in pressure loss is suppressed to about 100 to 200 mmAq even after 60 days. On the other hand, when the thickness of the diffuser plate exceeds 0.5 mm, the pressure loss significantly increases in a short period. Specifically, when the thickness of the diffuser plate is 0.8 mm, after 28 days, the increase value of pressure loss exceeds 250 mmAq, and when 1 mm, the increase value of pressure loss is only 21 days. Has reached 380 mmAq.

この原因は、散気板１の厚さが薄いと、開孔５への被処理水の入り込み量が少なくなり、また入り込んだ被処理水が滞留しにくく外部と入れ替わりやすいため、付着した微生物の発達による目詰まりが起こりにくくなるためと考えられる。このように、散気板の厚さを適切な範囲とすることによって、目詰まりによる圧力損失を抑制できることが本発明者らによって見出された。   This is because, if the thickness of the diffuser plate 1 is thin, the amount of water to be treated entering the opening 5 is small, and the water to be treated does not stay easily and is easily exchanged with the outside. It is thought that clogging due to development is less likely to occur. Thus, the present inventors have found that the pressure loss due to clogging can be suppressed by setting the thickness of the diffuser plate to an appropriate range.

したがって、圧力損失の上昇を１００〜２００ｍｍＡｑ程度に抑制するためには、散気板の厚さは０．１〜０．５ｍｍの範囲内とすることが望まれる。   Therefore, in order to suppress the increase in pressure loss to about 100 to 200 mmAq, it is desirable that the thickness of the diffuser plate be in the range of 0.1 to 0.5 mm.

圧力損失の上昇は、散気板の目詰まりを除去することによって抑制することができる。具体的には、定期的に薬剤を送気管に噴霧して目詰まりを除去することにより、散気板の圧力損失上昇を、長期にわたって抑制することができる。   An increase in pressure loss can be suppressed by removing clogging of the diffuser plate. Specifically, by periodically spraying the medicine on the air supply pipe to remove clogging, an increase in the pressure loss of the diffuser plate can be suppressed over a long period of time.

薬剤噴霧の効果を調べるため、短辺０．０４ｍｍ、長辺１．０ｍｍの開孔が設けられた厚さ０．３ｍｍの散気板を用意した。この散気板を下水処理槽中に設置して、前述と同様の条件で圧力損失の増加量を測定した。薬剤としては８５％の蟻酸を用い、１回当たり約５０ｇの薬液を１０分間で送気管へ噴霧した。薬剤の注入は、約６０日間間隔で行なった。前述と同様にして圧力損失の上昇値を測定し、その結果を図９のグラフに示す。   In order to investigate the effect of drug spraying, a 0.3 mm thick diffuser plate provided with openings having a short side of 0.04 mm and a long side of 1.0 mm was prepared. This diffuser plate was installed in a sewage treatment tank, and the amount of increase in pressure loss was measured under the same conditions as described above. As a drug, 85% formic acid was used, and about 50 g of chemical solution was sprayed onto the air supply tube in 10 minutes. The drug injection was performed at intervals of about 60 days. The rise value of the pressure loss was measured in the same manner as described above, and the result is shown in the graph of FIG.

圧力損失は、時間の経過とともに上昇して最大で２００ｍｍＡｑ程度に達するものの、薬剤の噴霧することによって５０ｍｍＡｑ程度まで低減される。このように、薬液の噴霧によって圧力損失を抑制できることが、図９のグラフからわかる。   Although the pressure loss rises with time and reaches a maximum of about 200 mmAq, it is reduced to about 50 mmAq by spraying the medicine. Thus, it can be seen from the graph of FIG. 9 that the pressure loss can be suppressed by spraying the chemical liquid.

薬剤の注入は、散気板の開孔が完全に目詰まらないうちに行なうことが望まれる。圧力損失の上昇を長期にわたって抑制するためには、被処理水内へ散気板を設置してから、圧力損失が２００ｍｍＡｑ程度上昇するまでに行なうことが望ましい。   It is desirable to inject the medicine before the opening of the diffuser plate is completely clogged. In order to suppress the increase in pressure loss over a long period of time, it is desirable that the pressure loss be increased by about 200 mmAq after the diffuser plate is installed in the water to be treated.

あるいは、目詰まりの発生自体を抑制することによって、目詰まりに伴なう散気板の圧力損失の上昇を低減することもできる。微生物の繁殖を抑制する成分を含有する材質で作製された散気板は、目詰まりの発生を抑制することができる。微生物の繁殖を抑制する成分としては、銀が挙げられる。   Alternatively, by suppressing the occurrence of clogging itself, an increase in the pressure loss of the diffuser plate due to clogging can be reduced. A diffuser plate made of a material containing a component that suppresses the growth of microorganisms can suppress the occurrence of clogging. Silver is mentioned as a component which suppresses reproduction of microorganisms.

銀を０．０４％含有する厚さ０．３ｍｍのステンレス製の薄板に、短辺０．０４ｍｍ、長辺１．０ｍｍの開孔を設けて散気板を作製した。この散気板を下水処理槽中に設置して、前述と同様の条件で圧力損失の増加量を測定した。前述と同様にして圧力損失の上昇値を測定し、その結果を図１０のグラフに示す。   A diffuser plate was prepared by providing an aperture with a short side of 0.04 mm and a long side of 1.0 mm on a 0.3 mm thick stainless steel plate containing 0.04% of silver. This diffuser plate was installed in a sewage treatment tank, and the amount of increase in pressure loss was measured under the same conditions as described above. The increase in pressure loss was measured in the same manner as described above, and the result is shown in the graph of FIG.

図１０のグラフに示されるように、６０日経過後の圧力損失は、銀を含有しない散気板の場合には２００ｍｍＡｑ程度に達しているのに対し、銀を含有する散気板での圧力損失は、その二分の一以下である。   As shown in the graph of FIG. 10, the pressure loss after 60 days has reached about 200 mmAq in the case of the diffuser plate not containing silver, whereas the pressure loss in the diffuser plate containing silver is about 200 mmAq. Is less than half of that.

散気板１の材料に微生物の繁殖を抑制する成分を含有させることによって、薬剤注入の間隔が長められるので、薬剤コストの削減にもつながる。   By including a component that suppresses the growth of microorganisms in the material of the diffuser plate 1, the interval between drug injections can be extended, leading to a reduction in drug cost.

本発明の一実施例にかかる散気装置の断面図。Sectional drawing of the air diffusion apparatus concerning one Example of this invention. 本発明の一実施例にかかる散気装置の平面図。The top view of the diffuser concerning one example of the present invention. 本発明の一実施例にかかる散気板の表面の拡大図。The enlarged view of the surface of the diffuser plate concerning one Example of this invention. スリット短辺長さと圧力損失および生成気泡径との関係を示すグラフ図。The graph which shows the relationship between a slit short side length, a pressure loss, and a production | generation bubble diameter. 開孔面積率と酸素移動効率との関係を示すグラフ図。The graph which shows the relationship between a hole area ratio and oxygen transfer efficiency. 本発明の他の実施例にかかる散気装置を示す断面図。Sectional drawing which shows the air diffusion apparatus concerning the other Example of this invention. スリット長辺長さの違いによる圧力損失上昇の経時変化を示すグラフ図。The graph which shows the time-dependent change of the pressure loss raise by the difference in the slit long side length. 散気板厚さの違いによる圧力損失上昇の経時変化を示すグラフ図。The graph which shows the time-dependent change of the pressure loss rise by the difference in a diffuser board thickness. 圧力損失上昇の経時変化における薬剤注入の効果を示すグラフ図。The graph which shows the effect of the chemical | medical agent injection | pouring in the time-dependent change of a pressure loss rise. 圧力損失上昇の経時変化における散気板の材質の効果を示すグラフ図。The graph which shows the effect of the material of a diffuser board in the time-dependent change of a pressure loss rise.

符号の説明Explanation of symbols

１…散気板； ２…散気板固定枠； ３…送気管； ４…ケーシング； ５…開孔
６…開孔の短辺； ７…開孔の長辺； ８…短辺方向のピッチ
９…長辺方向のピッチ； １０…散気装置； １１…逆止弁； １２…元管
１３…間隙。 DESCRIPTION OF SYMBOLS 1 ... Diffusing plate; 2 ... Diffusing plate fixed frame; 3 ... Air supply pipe; 4 ... Casing; 5 ... Opening 6 ... Short side of opening; 7 ... Long side of opening; 9 ... Pitch in the long side direction; 10 ... Air diffuser; 11 ... Check valve; 12 ... Main pipe 13 ... Gap.

Claims (9)

複数の開孔を有する薄板からなり、前記開孔を通して液体中に気泡を分散させる散気板であって、
前記開孔は、向かい合う短辺と長辺とにより構成された四角形形状を有し、
前記短辺方向の間隙のうち、最も広い部分の長さは０．０３ｍｍ〜０．１５ｍｍであることを特徴とする散気板。 A diffuser plate comprising a thin plate having a plurality of apertures, wherein air bubbles are dispersed in the liquid through the apertures,
The opening has a quadrangular shape composed of a short side and a long side facing each other,
The diffuser plate according to claim 1, wherein the length of the widest portion of the gap in the short side direction is 0.03 mm to 0.15 mm. 前記開孔の総面積は、前記散気板の面積の０．０５〜１．０％を占めることを特徴とする請求項１に記載の散気板。   The diffuser plate according to claim 1, wherein a total area of the openings occupies 0.05 to 1.0% of an area of the diffuser plate. 前記開孔の長辺方向の長さは、０．１〜１．５ｍｍであることを特徴とする請求項１または２に記載の散気板。   The diffuser plate according to claim 1 or 2, wherein a length of the opening in a long side direction is 0.1 to 1.5 mm. 前記薄膜の厚さは、０．１〜０．５ｍｍであることを特徴とする請求項３に記載の散気板。   The diffuser plate according to claim 3, wherein the thin film has a thickness of 0.1 to 0.5 mm. 前記薄膜は、微生物の繁殖を抑制する材料を含むことを特徴とする請求項３または４に記載の散気板。   The diffuser plate according to claim 3 or 4, wherein the thin film includes a material that suppresses the growth of microorganisms. 前記微生物の繁殖を抑制する材料は、銀であることを特徴とする請求項５に記載の散気板。   The diffuser plate according to claim 5, wherein the material that suppresses the growth of microorganisms is silver. ケーシングと、
散気板固定枠により前記ケーシングに固定された請求項１または２に記載の散気板と、
前記ケーシングに連通した送気管とを具備し、
前記送気管と前記ケーシングとの間、または前記ケーシングの内部に、逆止弁が装着されていることを特徴とする散気装置。 A casing,
The diffuser plate according to claim 1 or 2, which is fixed to the casing by a diffuser plate fixing frame,
An air pipe communicating with the casing;
An air diffuser, wherein a check valve is mounted between the air supply pipe and the casing or inside the casing. ケーシングと、散気板固定枠により前記ケーシングに固定された散気板と、前記ケーシングに連通した送気管とを具備する散気装置における散気板の目詰まりを除去する方法であって、
前記送気管内に薬剤を噴霧することを特徴とする除去方法。 A method of removing clogging of a diffuser plate in a diffuser comprising a casing, a diffuser plate fixed to the casing by a diffuser plate fixing frame, and an air supply pipe communicating with the casing,
A removal method comprising spraying a drug into the air supply tube. 前記薬剤として蟻酸を用いることを特徴とする請求項８に記載の散気板の目詰まり除去方法。   The method for removing clogging of a diffuser plate according to claim 8, wherein formic acid is used as the drug.
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