CN110621392A

CN110621392A - Filter device

Info

Publication number: CN110621392A
Application number: CN201980002413.4A
Authority: CN
Inventors: 池田启一; 松本岳; 佐藤长久; 森田徹
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2018-04-19
Filing date: 2019-02-06
Publication date: 2019-12-27
Anticipated expiration: 2039-02-06
Also published as: CN110621392B; TW201943451A; JP2019188275A; WO2019202822A1

Abstract

A filter device according to one aspect of the present disclosure is provided with: a plurality of filtration modules, each filtration module including a plurality of hollow fiber membranes arranged in a vertical direction and a pair of holding members having holding regions for fixing top and bottom ends of the plurality of hollow fiber membranes; a support holding a plurality of filter modules in a row such that the plurality of filter modules are parallel to each other and arranged at equal intervals; one or more gas supply modules that supply bubbles from below the plurality of filtration modules, wherein the plurality of hollow fiber membranes are mainly composed ofIs divided into polytetrafluoroethylene, and (C)²‑A²)^0.5The value of/2B is 10 to 20, where a is an average interval between the pair of holding members in the plurality of filtration modules, B is an average interval between holding regions of the plurality of hollow fiber membranes of the filtration modules adjacent to each other, and C is an average effective length upon wetting of the plurality of hollow fiber membranes exposed between the pair of holding members.

Description

Filter device

Technical Field

The present disclosure relates to a filtering apparatus.

The present application is based on and claims priority from japanese patent application 2018-80410 filed on 19.4.2018, the entire contents of which are incorporated herein by reference.

Background

For example, in drainage treatment or the like, a liquid may be filtered using a filtration membrane. In order to achieve such filtration, an immersion type filtration module is used in which a plurality of hollow fiber membranes are arranged in one direction, both ends of the plurality of hollow fiber membranes are held by a pair of holding members, and one or both of the holding members are provided with a flow path communicating with the lumens of the plurality of hollow fiber membranes. Such a filtration module is immersed in an untreated liquid stored in a container at the time of use, and is used for constructing a filtration system in which a filtered liquid that has permeated the hollow fiber membranes and has flowed into the lumens of the hollow fiber membranes is sucked through the flow path of the holding member and extracted to the outside.

Japanese patent application publication 2013-56364 discloses a filtration module using a hollow fiber membrane formed of Polytetrafluoroethylene (PTFE). In the above-mentioned application publication, it is described that the effect of peeling off and removing suspended matter attached on the outer peripheral surfaces of a plurality of hollow fiber membranes can be achieved by supplying air bubbles from below toward the hollow fiber membranes extending in the up-down direction and shaking the hollow fiber membranes.

Documents of the prior art

Patent document

Patent document 1: japanese patent application publication 2013-56364

Disclosure of Invention

According to one aspect of the present disclosure, a filtering apparatus includes: a plurality of filtration modules, each of which includes a plurality of hollow fiber membranes arranged in an up-down direction and a pair of holding members having holding regions for fixing top and bottom ends of the plurality of hollow fiber membranes; a support for holding the plurality of filter modules such that the plurality of filter modules are arranged in parallel at equal intervals; one or more gas supply modules for supplying gas bubbles from below the plurality of filtration modules, wherein the plurality of hollow fiber membranes contain polytetrafluoroethylene as a main component, an average interval in the up-down direction between the pair of holding members of the plurality of filtration modules is denoted by a, an average interval between holding regions of the plurality of hollow fiber membranes of adjacent filtration modules is denoted by B, and an average effective length in wetting of the plurality of hollow fiber membranes exposed between the pair of holding members is denoted by C, (C) a²-A²)^0.5The value of/2B is greater than or equal to 10 and less than or equal to 20.

Drawings

FIG. 1 is a schematic diagram illustrating a filtration system having a filtration apparatus according to an embodiment of the present disclosure;

fig. 2 is a schematic perspective view showing a filter module and a cleaning module in a state of being held by the filter apparatus of fig. 1;

FIG. 3 is a schematic horizontal cross-sectional view of the filtration module of FIG. 2;

fig. 4 is a schematic view showing a relationship between hollow fiber membranes and a holding member of a filtration module in the filtration apparatus of fig. 1; and

fig. 5 is a schematic vertical cross-sectional view of the filtration module of fig. 2.

Detailed Description

[ problem to be solved by the present disclosure ]

As disclosed in the above publication, in order to vigorously shake the hollow fiber membranes by the bubbles, the hollow fiber membranes must have a certain extra length, i.e., the hollow fiber membranes have slack. However, if the hollow fiber membranes are excessively relaxed, the hollow fiber membranes may be entangled with each other, thereby further promoting clogging due to suspended matter or the like.

In view of the above problems, it is an object of the present disclosure to provide a filtering apparatus capable of efficiently removing suspended matter attached to hollow fiber membranes by air bubbles.

[ Effect of the present disclosure ]

According to the filtration apparatus of the aspect of the present disclosure, suspended matter attached to the hollow fiber membranes can be efficiently removed by the air bubbles.

[ description of embodiments of the present disclosure ]

According to one aspect of the present disclosure, a filtering apparatus includes: a plurality of filtration modules, each of which includes a plurality of hollow fiber membranes arranged in an up-down direction and a pair of holding members having holding regions for fixing top and bottom ends of the plurality of hollow fiber membranes; a support for holding the plurality of filter modules such that the plurality of filter modules are arranged in parallel at equal intervals; and one or more gas supply modules for supplying bubbles from below the plurality of filtration modules, wherein the plurality of hollow fiber membranes contain polytetrafluoroethylene as a main component, an average interval in the up-down direction between the pair of holding members of the plurality of filtration modules is represented by a, an average interval between holding regions of the plurality of hollow fiber membranes of adjacent filtration modules is represented by B, and an average effective length in wetting of the plurality of hollow fiber membranes exposed between the pair of holding members is represented by C, (C) is²-A²)^0.5The value of/2B is greater than or equal to 10 and less than or equal to 20.

In the filter device, (C)²-A²)^0.5The value of/2B is within the above range, so the hollow fiber membranes can be shaken by the bubbles supplied from the gas supply module, and the hollow fiber membranes hardly tangle with each other. As a result, the filtering apparatus can effectively remove suspended matters attached to the hollow fiber membranes by the air bubbles.

In the filtration apparatus, the average effective length of the hollow fiber membranes exposed between the pair of holding members at the time of drying is preferably larger than the average interval a in the up-down direction between the pair of holding members. In this way, since the average effective length of the hollow fiber membranes exposed between the pair of holding members at the time of drying is larger than the average interval between the pair of holding members, when the filter module is not used, the hollow fiber membranes can be prevented from being damaged by unnecessary tension.

In the filter apparatus, the average interval a in the up-down direction between the pair of holding members is preferably greater than or equal to 2.0m and less than or equal to 4.0 m. In this way, when the average interval a in the up-down direction between the pair of holding members is within the above range, the advantage of applying the present disclosure becomes remarkable as compared with the conventional filtration apparatus in which entanglement of hollow fiber membranes easily occurs.

In the filter device, the average interval B between the holding areas is preferably greater than or equal to 15mm and less than or equal to 50 mm. In this way, since the average interval B between the holding regions is within the above range, it is possible to improve the filtration capacity by increasing the number per unit volume of the hollow fiber membranes while more reliably preventing entanglement of the hollow fiber membranes. Here, the "holding region" refers to a smallest rectangular region surrounding the fixed hollow fiber membranes in the holding member.

In the filtration apparatus, the average outer diameter of the hollow fiber membranes is preferably greater than or equal to 1.5mm and less than or equal to 4.0 mm. In this way, since the average outer diameter of the hollow fiber membranes is within the above range, the filtration capacity can be further improved by further increasing the number per unit volume of the hollow fiber membranes.

Here, "wet" refers to a state in which the hollow fiber membranes are immersed in a liquid for 2 weeks or longer, and "dry" refers to a state in which the hollow fiber membranes are left in the air for 2 weeks or longer. Further, in the present specification, the "average" value refers to an arithmetic average of values measured for a plurality of filter modules provided in the filter apparatus. For example, the "average interval between the holding members" is an arithmetic average of intervals between the holding members in the plurality of filter modules provided in the filter apparatus.

[ details of embodiments of the present disclosure ]

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

The filtration system of fig. 1 comprises a filtration vessel W storing untreated liquid to be filtered, and a filtration apparatus 1 according to an embodiment of the present disclosure disposed in the filtration vessel W. Hereinafter, in fig. 1, the up-down direction is described as a Z direction, the left-right direction is described as an X direction, and the depth direction of the paper surface is described as a Y direction.

[ filtration Container ]

The filtration vessel W stores untreated liquid so that the filtration apparatus 1 is immersed in the untreated liquid.

As the material of the filter vessel W, for example, resin, metal, concrete, or the like can be used.

[ filtration apparatus ]

The filtering apparatus includes: a plurality of filter modules 2; a support 3 for holding the plurality of filter modules 2 such that the plurality of filter modules 2 are arranged in parallel at equal intervals; a gas supply module 4 for supplying bubbles G from below the filter module 2; and a discharge mechanism 5 for discharging the treated liquid from the filtration module 2. The treated liquid is obtained by filtering untreated liquid by the plurality of filter modules 2.

[ filtration Module ]

As shown in fig. 1 and 2, each filter module 2 includes: a plurality of hollow fiber membranes 6, the plurality of hollow fiber membranes 6 being arranged along the up-down direction (Z direction); an upper holding member 7 for fixing the tips of the plurality of hollow fiber membranes 6; and a lower holding member 8 for fixing the bottom ends of the plurality of hollow fiber membranes 6. The upper holding member 7 and the lower holding member 8 constitute a pair of holding members.

In each of the plurality of filtration modules 2 of the filtration apparatus 1, the upper holding member 7 and the lower holding member 8 are formed in an elongated rod shape along the Y direction, and the plurality of hollow fiber membranes 6 are arranged side by side in a curtain shape along the longitudinal direction (Y direction) of the upper holding member 7 and the lower holding member 8. That is, as shown in fig. 3, the upper holding member 7 and the lower holding member 8 hold the plurality of hollow fiber membranes 6 such that the plurality of hollow fiber membranes 6 are arranged in the elongated rectangular holding region R. Since the hollow fiber membranes 6 are arranged in the curtain shape in this way, the gas bubbles G can reach the central portion of the hollow fiber membranes 6 relatively easily in the thickness direction (X direction) of the curtain-shaped portion of the hollow fiber membranes 6, and hence the effect of removing suspended matter by the gas supply module 4 described below can be promoted.

As shown in fig. 4, when the average interval in the up-down direction between the pair of holding members 7 and 8 of the filter module 2 is denoted by a, the average interval between the holding regions R of the hollow fiber membranes 6 of the adjacent filter modules is denoted by B, and the average effective length when wet of the hollow fiber membranes 6 exposed between the pair of holding members 7 and 8 is denoted by C, (C)²-A²)^0.5The lower limit value of the value of/2B is 10, preferably 12. (C)²-A²)^0.5The upper limit value of the value of/2B is 20, preferably 18. When (C)²-A²)^0.5When the value of/2B is less than the above-described lower limit value, the shaking of the hollow fiber membranes 6 may be insufficient, and thus the effect of removing suspended matter by air bubbles may not be sufficiently promoted. On the contrary, when (C)²-A²)^0.5When the value of/2B is larger than the above upper limit value, the hollow fiber membranes 6 may easily tangle with each other, and thus the removal of suspended matter by air bubbles may be suppressed. Here, the "average effective length" refers to an average of lengths (lengths along respective axial directions of the hollow fiber membranes) of effective portions of the hollow fiber membranes, which are exposed between the pair of holding membersAnd (4) partial.

In the filtration module 2, in order to prevent damage of the hollow fiber membranes 6 caused by unnecessary tension acting on the hollow fiber membranes 6 when the filtration module 2 is not used, the average effective length at the time of drying of the hollow fiber membranes 6 exposed between the pair of holding members 7 and 8 is preferably larger than the average interval a in the up-down direction between the pair of holding members 7 and 8.

In the filter module 2, the lower limit value of the average interval a in the up-down direction (Z direction) between the holding members 7 and 8 is preferably 2.0m, and more preferably 2.5 m. The upper limit value of the average interval a in the up-down direction between the holding members 7 and 8 is preferably 4.0m, and more preferably 3.5 m. When the average interval a in the up-down direction between the holding members 7 and 8 is smaller than the above-described lower limit value, the advantage of applying the present disclosure may not be significant as compared with a conventional filtration apparatus in which entanglement of hollow fiber membranes is liable to occur. In contrast, when the average interval a in the up-down direction between the holding members 7 and 8 is larger than the above-described upper limit value, since the effective length of the hollow fiber membranes 6 is increased, the hollow fiber membranes 6 are easily stretched due to their own weight or the like, and thus entanglement of the hollow fiber membranes 6 may not be sufficiently suppressed even by the present disclosure.

The lower limit value of the average interval B between the holding regions R of the adjacent filter modules 2 in the X direction shown in fig. 3 is preferably 15mm, and more preferably 20 mm. The upper limit value of the average interval B between the holding regions R is preferably 50mm, and more preferably 40 mm. When the average interval B between the holding regions R is kept smaller than the above-described lower limit value, it may be difficult to prevent entanglement of the hollow fiber membranes 6 between the filtration modules 2, and the effect of removing suspended matter by air bubbles may not be sufficiently promoted. In contrast, when the average interval B between the holding regions R is larger than the above-described upper limit value, since the membrane area per unit volume of the filter device 1 is reduced, the processing capacity of the filter device 1 may become insufficient.

< hollow fiber Membrane >

The hollow fiber membrane 6 is prepared by forming a porous membrane, which allows penetration of a liquid but does not allow penetration of particles contained in an untreated liquid, into a tubular shape.

The main component of the hollow fiber membrane 6 is PTFE (polytetrafluoroethylene). In this way, since the main component is PTFE, hollow fiber membrane 6 has excellent chemical resistance, heat resistance, weather resistance, flame retardancy, and the like. Note that other polymers and additives (such as a lubricant and the like) other than PTFE may be appropriately added to the hollow fiber membranes 6.

The hollow fiber membrane 6 is preferably made porous PTFE by stretching. The stretching of PTFE may be uniaxial stretching or biaxial stretching.

The lower limit value of the tensile strength of the hollow fiber membrane 6 is preferably 50MPa, and more preferably 60 MPa. When the tensile strength of the hollow fiber membrane 6 is less than the above lower limit value, the durability of the surface subjected to cleaning with air bubbles may be reduced. The upper limit of the tensile strength of the hollow fiber membrane 6 is usually 150N. The tensile strength refers to the maximum tensile stress observed in a tensile test conducted in accordance with JIS-K7161(1994) at a gauge length of 100mm and a test speed of 100 mm/min.

The lower limit value of the average outer diameter of the hollow fiber membranes 6 is preferably 1.5mm, and more preferably 2.0 mm. The upper limit value of the average outer diameter of the hollow fiber membranes 6 is preferably 4.0mm, and more preferably 3.0 mm. When the average outer diameter of the hollow fiber membranes 6 is smaller than the above-described lower limit value, the mechanical strength of the hollow fiber membranes 6 may become insufficient, and the cross-sectional area of the inner cavities of the hollow fiber membranes 6 may decrease, and thus the filtration capacity may become insufficient. In contrast, when the average outer diameter of the hollow fiber membranes 6 is larger than the above upper limit value, the total area of the hollow fiber membranes 6 may be reduced, and thus the filtration capacity may become insufficient.

The lower limit value of the average inner diameter of the hollow fiber membranes 6 is preferably 0.3mm, and more preferably 0.5 mm. The upper limit value of the average inner diameter of the hollow fiber membranes 6 is preferably 3.0mm, and more preferably 2.0 mm. When the average inner diameter of the hollow fiber membranes 6 is less than the above-described lower limit value, the pressure drop during the process of discharging the filtered liquid inside the hollow fiber membranes 6 may increase. In contrast, when the average inner diameter of the hollow fiber membranes 6 is larger than the above upper limit value, the mechanical strength of the hollow fiber membranes 6 and the ability to prevent penetration of solid substances may become insufficient.

The lower limit value of the porosity of the hollow fiber membrane 6 is preferably 70%, and more preferably 75%. The upper limit value of the porosity of the hollow fiber membrane 6 is preferably 90%, and more preferably 85%. When the porosity of the hollow fiber membrane 6 is less than the above-described lower limit value, the permeability may be insufficient. In contrast, when the porosity of the hollow fiber membranes 6 is larger than the above upper limit value, the mechanical strength and abrasion resistance of the hollow fiber membranes 6 may become insufficient. Porosity refers to the ratio of the total volume of pores to the volume of hollow fiber membranes 6, and can be determined by measuring the density of hollow fiber membranes 6 according to ASTM-D-792.

The hollow fiber membrane 6 may be configured to have a porous tubular substrate layer and a porous filtration layer stacked on the outer circumferential surface of the substrate layer. In this way, since the hollow fiber membranes 6 have such a multilayer structure, permeability and mechanical strength can be achieved, and thus suspended matter can be more effectively removed by air bubbles.

(base layer)

The main component of the substrate layer is PTFE. In this way, since the main component is PTFE, hollow fiber membrane 6 has excellent chemical resistance, heat resistance, weather resistance, flame retardancy, and the like. Note that other polymers and additives (such as a lubricant and the like) other than PTFE may be appropriately added to the base layer.

The substrate layer is preferably made porous PTFE by stretching. The stretching of PTFE may be uniaxial stretching or biaxial stretching.

The lower limit value of the number average molecular weight of the PTFE of the substrate layer is preferably 500000, and more preferably 2000000. The upper limit value of the number average molecular weight of the PTFE of the substrate layer is preferably 20000000. When the number average molecular weight of the PTFE of the substrate layer is less than the above-described lower limit value, the surface of the hollow fiber membrane 6 may be easily damaged, and the mechanical strength of the hollow fiber membrane 6 may be reduced. In contrast, when the number average molecular weight of the PTFE of the substrate layer is larger than the above upper limit value, it may be difficult to form pores in the hollow fiber membrane 6.

The substrate layer may be a tube made, for example, by extrusion of PTFE. In this way, since such an extrusion-molded tube is used as the base layer, the base layer can exhibit mechanical strength and can easily form a hole.

(Filter layer)

The filter layer may be formed by spirally winding a strip on the substrate layer such that two edges of the strip overlap.

The lower limit value of the overlapping area ratio of the strips in the filter layer is preferably 20%, and more preferably 25%. The upper limit value of the overlapping area ratio of the strips in the filter layer is preferably 40%, and more preferably 35%. When the overlapping area ratio of the strips in the filter layer is less than the above-described lower limit value, it may be difficult to wind the strips so that no gap is formed between the edges of the strips, and the production efficiency of the hollow fiber membrane 6 may become insufficient. In contrast, when the overlapping area ratio of the strips in the filter layer is larger than the above-described upper limit value, the filtration capacity (flow rate) of the hollow fiber membranes 6 may be unnecessarily reduced.

The material of the filter layer may be the same as the material of the substrate layer. The filtration layer is preferably made porous PTFE by stretching, and more preferably is multi-axially stretched to form uniform pores.

The lower limit value of the average thickness of the filter layer is preferably 1 μm, and more preferably 2 μm. The upper limit value of the average thickness of the filter layer is preferably 100 μm, and more preferably 80 μm. When the average thickness of the filtration layer is less than the above-described lower limit value, the ability of the hollow fiber membranes 6 to prevent penetration of solid matter may become insufficient. In contrast, when the average thickness of the filtration layer is larger than the above upper limit value, the flow rate of the liquid permeating the hollow fiber membranes 6 may become insufficient.

The lower limit value of the average diameter of the pores of the hollow fiber membranes 6 is preferably 0.01 μm. The upper limit value of the average diameter of the pores of the hollow fiber membranes 6 is preferably 0.45 μm, and more preferably 0.1 μm. When the average diameter of the pores of the hollow fiber membrane 6 is smaller than the above-described lower limit value, the permeability may be decreased. In contrast, when the average diameter of the pores of the hollow fiber membranes 6 is larger than the above upper limit value, it may be impossible to prevent impurities contained in the untreated liquid from penetrating into the interior of the hollow fiber membranes 6. Note that the average diameter of the pores refers to the average diameter of the pores in the outer peripheral surface (the surface of the filter layer) of the hollow fiber membrane 6, and may be measured using a pore size distribution measuring apparatus (for example, a "porous material automatic pore size distribution measuring system" commercially available from porous material limited).

As described above, both ends of the hollow fiber membranes 6 are arranged in a matrix shape along the long-side direction and the short-side direction in the rectangular holding regions R of the upper holding member 7 and the lower holding member 8.

The lower limit value of the ratio (La/Lb) of the average length La in the long side direction to the average length Lb in the short side direction of the holding region R is preferably 10, and more preferably 20. The upper limit value of the ratio of the average length La in the long side direction to the average length Lb in the short side direction of the holding region R is preferably 50, and more preferably 40. When the ratio of the average length La in the long side direction to the average length Lb in the short side direction is smaller than the above-described lower limit value, the length in the short side direction may be excessively large, and therefore air bubbles may not be supplied to the central portion of the bundle of hollow fiber membranes 6, and the area of the holding region R may become too small to obtain a sufficient filtration area. In contrast, when the ratio of the average length La in the long side direction to the average length Lb in the short side direction of the holding region R is larger than the above-described upper limit value, the filter module 2 may excessively extend in the long side direction, and thus the operation of the filter module 2 may become difficult.

The lower limit value of the ratio of the average pitch of the hollow fiber membranes 6 in the long side direction (the distance between the centers of the hollow fiber membranes 6) to the average pitch in the short side direction in the holding region R is preferably 1.2, and more preferably 1.5. The upper limit value of the ratio of the average pitch in the long side direction to the average pitch in the short side direction of the hollow fiber membranes 6 in the holding region R is preferably 2.5, and more preferably 2.0. When the ratio of the average pitch of the hollow fiber membranes 6 in the long side direction to the average pitch in the short side direction in the holding region R is smaller than the above-described lower limit value, sufficient air bubbles may not be introduced into the gap between the hollow fiber membranes 6 in the short side direction of the holding region R. In contrast, when the ratio of the average pitch of the hollow fiber membranes 6 in the long side direction to the average pitch in the short side direction is larger than the above-described upper limit value, the density of the hollow fiber membranes 6 in the long side direction may decrease, and the filtration capacity may become insufficient.

The lower limit value of the cross-sectional occupancy of the hollow fiber membranes 6 (area occupancy including the lumen area of the hollow fiber membranes 6) in the holding region R is preferably 30%, and more preferably 32%. The upper limit value of the cross-sectional occupancy of the hollow fiber membranes 6 in the holding region R is preferably 40%, and more preferably 38%. When the cross-sectional occupancy of the hollow fiber membranes 6 is less than the above-described lower limit value, the number per unit area of the hollow fiber membranes 6 may decrease, and sufficient filtration efficiency may not be obtained. In contrast, when the cross-sectional occupancy of the hollow fiber membranes 6 is greater than the above-described upper limit value, the gaps between the hollow fiber membranes 6 may become excessively small, and air bubbles may not be supplied to the hollow fiber membranes 6 inside the holding region R, and thus it may be impossible to suppress the adhesion of suspended matter to the hollow fiber membranes 6. Here, the cross-sectional occupancy refers to a ratio of the total cross-sectional area of the hollow fiber membranes 6 to the area of the holding region R.

The lower limit value of the number of hollow fiber membranes 6 arranged in the short side direction in the holding region R (the arrangement number) is preferably 8, and more preferably 12. The upper limit value of the hollow fiber membranes 6 arranged in the short side direction is preferably 50, and more preferably 40. When the number of hollow fiber membranes 6 arranged in the short side direction is less than the above-described lower limit value, the filtration area per arrangement region may not be sufficiently obtained. In contrast, when the number of hollow fiber membranes 6 arranged in the short-side direction is larger than the above-described upper limit value, it may become difficult to supply air bubbles to the central portion of the bundle of hollow fiber membranes 6 in the short-side direction, and a sufficient cleaning effect may not be achieved.

The lower limit value of the ratio of the average pitch in the short side direction (the distance between the centers of the hollow fiber membranes 6) to the average outer diameter of the hollow fiber membranes 6 in the holding region R is preferably 1.0. The upper limit value of the ratio of the average pitch in the short-side direction to the average outer diameter of the hollow fiber membranes 6 is preferably 1.5, and more preferably 1.4. When the ratio of the average pitch in the short-side direction to the average outer diameter of the hollow fiber membranes 6 is smaller than the above-described lower limit value, the hollow fiber membranes 6 are arranged in a flattened state in the radial direction, and therefore manufacturing may become difficult. In contrast, when the ratio of the average pitch in the short-side direction to the average outer diameter of the hollow fiber membranes 6 is larger than the above-described upper limit value, the density of the hollow fiber membranes 6 in the long-side direction decreases, and therefore the filtration capacity may become insufficient.

The plurality of hollow fiber membranes 6 may be configured to be divided into a plurality of bundles along the longitudinal direction (Y direction) of the upper holding member 7 and the lower holding member 8. That is, the upper holding member 7 and the lower holding member 8 may have a plurality of regions in which the plurality of hollow fiber membranes 6 are densely arranged at intervals in the longitudinal direction. In this way, since the plurality of hollow fiber membranes 6 are divided into the plurality of bundles and gaps are provided between the bundles, the bundles of hollow fiber membranes 6 can be vibrated in the longitudinal direction of the upper holder member 7 and the lower holder 8, and therefore suspended matter attached on the surfaces of the hollow fiber membranes 6 can be efficiently shaken off by the vibration. Further, since there is a gap between the bundles of hollow fiber membranes 6, the gas bubbles G can reach the inside of the hollow fiber membranes 6 relatively easily in the longitudinal direction of the upper holding member 7 and the lower holding member 8, and therefore the effect of removing suspended matter by the gas bubbles supplied from the gas supply module 4 described later can be further promoted.

< Upper holding Member >

The upper holding member 7 is a member for holding the tip portions of the plurality of hollow fiber membranes 6, and has an internal flow path that communicates with the inner cavities of the plurality of hollow fiber membranes 6 and collects the filtered liquid. The pipe of the discharge mechanism 5 is connected to the internal flow path, and the filtered liquid that has permeated the inside of the plurality of hollow fiber membranes 6 is discharged.

The upper holding member 7 has a shape elongated in the horizontal direction (the direction perpendicular to the direction in which the hollow fiber membranes 6 are aligned) and has a substantially constant width. The sectional shape of the upper holding member 7 is not particularly limited, and may be, for example, a polygon, a circle, or the like. Here, the upper holding member 7 is adapted to take a rectangular shape that facilitates formation and fixation of the plurality of hollow fiber membranes 6. Further, the upper holding member 7 may have an engagement structure for facilitating support by the support 3.

As a specific example, as shown in fig. 5, the upper holding member 7 may be configured to include a hollow housing 7a having a bottom opening into which top end portions of the plurality of hollow fiber membranes 6 are inserted from below.

In this example, the upper holding member 7 includes a resin composition 7b filled between the inner side wall surface of the hollow shell 7a and the outer peripheral surface of the hollow fiber membrane 6 so as to leave an internal space, which forms the discharge portion. Specifically, a bundle of hollow fiber membranes 6 having a tip portion bonded with resin composition 7b in advance is inserted into hollow housing 7a, and resin composition 7b is further supplied to fill the gap in resin composition 7b and the gap between resin composition 7b and the inner wall of hollow housing 7 a. As a result, hollow fiber membranes 6 are fixed with respect to hollow shell 7 a.

The hollow housing 7a is provided with a discharge nozzle 7c which communicates with the inner space and is connected to a discharge mechanism.

The material for the hollow shell 7a includes, for example, a resin composition containing PTFE, vinyl chloride, polyethylene, ABS resin, or the like as a main component.

The resin composition 7b may be any resin composition having high adhesion to the hollow fiber membranes 6 and the hollow shell 7a and capable of being cured inside the hollow shell 7 a. In particular, when the hollow fiber membranes 6 composed of PTFE are used, the main component of the resin composition 7b is preferably an epoxy resin or a polyurethane resin that can reliably prevent the detachment of the hollow fiber membranes 6 and has high adhesion to PTFE. Since the hollow shell 7a is filled with the resin composition 7b, the space between the hollow fiber membranes 6 and the side wall of the hollow shell 7a can be hermetically sealed. As a result, the discharge portion inside the upper holding member 7 and the outside of the hollow fiber membranes 6 can be reliably separated, and therefore the filtered liquid can be prevented from being contaminated by the unfiltered liquid.

< lower holding Member >

The lower holding member 8 is a member for holding the bottom end portions of the plurality of hollow fiber membranes 6. The lower holding member 8 may have a similar structure to the upper holding member 7, or may not have a discharge portion for sealing the bottom end portions of the hollow fiber membranes 6. The structure, average width, average length, material, etc. of the lower holding member 8 may be the same as those of the upper holding member 7.

Further, the lower holding member 8 may have a structure in which: wherein one hollow fiber membrane 6 is bent and folded back into a U-shape. In this case, the upper holding member 7 holds both ends of the hollow fiber membranes 6.

[ Supports ]

As described above, the support 3 holds the upper holding member 7 and the lower holding member 8 of the plurality of filtration modules 2 so that the plurality of filtration modules 2 are set in an immersed state immersed in the untreated liquid stored in the filtration vessel W.

The support 3 is preferably configured to enable the filter module 2 to be removed from the filter vessel W while holding the filter module 2. Further, the support 3 is preferably configured to hold a gas supply module 4 described later below the filter module 2.

[ gas supply Module ]

The gas supply module 4 is disposed between the filter modules 2 in a plan view, and has a plurality of gas supply conduits 9 that supply gas for forming the bubbles G. The plurality of gas supply conduits 9 have a plurality of bubble discharge ports 9a for discharging bubbles G. The diameter of the bubble discharge port 9a of the gas supply conduit 9 may be, for example, 1mm or more and 10mm or less. The gas supply module 4 supplies gas bubbles G from the gap of the lower holding member 8 to the hollow fiber membranes 6, and removes suspended matter attached to the hollow fiber membranes 6 by shaking the hollow fiber membranes 6.

Note that the gas for forming the bubbles G supplied from the gas supply module 4 may be any inert gas, and is not particularly limited, and is preferably air from the viewpoint of operation cost.

[ discharge mechanism ]

The discharge mechanism 5 is connected to the discharge nozzles 7c of the plurality of filtration modules 2, and includes a collection pipe 10 for collecting the treated liquid that has been filtered by the hollow fiber membranes 6, and a suction pump 11 for sucking the treated liquid from the collection pipe 10.

[ advantages ]

In the filter device 1, (C)²-A²)^0.5The value of/2B is within the above range, and therefore the hollow fiber membranes 6 can be shaken by the bubbles supplied from the gas supply module 4, and the hollow fiber membranes 6 hardly tangle with each other. As a result, the filtration apparatus 1 can efficiently remove suspended matters attached to the hollow fiber membranes 6 by the air bubbles.

[ other examples ]

The embodiments disclosed herein are merely exemplary in all respects and should not be considered as limiting. The scope of the present invention is not limited to the structures of the above-described embodiments but is defined by the claims, and is intended to include all modifications and equivalents within the meaning and scope of the claims.

In the filtering apparatus, the configuration of the gas supply module is not limited, and may be, for example, a means for flowing gas out of a porous plate, a means for injecting gas from a diffuser, a distributor, or the like, a means for intermittently injecting bubbles, a bubble jet nozzle for mixing and injecting bubbles in a water flow, or the like.

The filter device may not have a drainage mechanism. As an example, the filtering apparatus may be an apparatus that sucks filtered liquid by an external suction device, or an apparatus configured to be able to raise the pressure inside the container and cause the liquid to permeate the hollow fiber membranes and flow out to the outside of the apparatus by the external pressure.

Example

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not to be construed restrictively based on the description of the examples.

< sample 1 for trial production >

A plurality of pilot samples 1 of the filtration module were prepared by the following procedure. A plurality of hollow fiber membranes made of PTFE having an outer diameter of 2.3mm, an inner diameter of 1.1mm, a membrane thickness of 0.6mm, and a porosity of 80% were prepared, both ends of the hollow fiber membranes were fixed by a pair of holding members so that the average effective length (C) of the hollow fiber membranes when wet was 3100mm, and the pair of holding members were connected by a supporting member so that the average interval (a) between the pair of holding members was 3060 mm.

< sample 2 for trial production >

A plurality of trial samples 2 of the filtration module were prepared similarly to trial sample 1 except that the average effective length (C) of the plurality of hollow fiber membranes when wet was 3140 mm.

< sample 3 for trial production >

A plurality of trial samples 3 of the filtration module were prepared similarly to trial sample 1, except that the average effective length (C) of the plurality of hollow fiber membranes when wet was 3200 mm.

< trial sample 4>

A plurality of trial samples 4 of the filtration module were prepared similarly to trial sample 1, except that the average effective length (C) of the plurality of hollow fiber membranes when wet was 3230 mm.

< sample 5 for trial production >

A plurality of trial samples 5 of the filtration module were prepared similarly to trial sample 1, except that the average effective length (C) of the plurality of hollow fiber membranes when wet was 3260 mm.

< sample 6 for trial production >

A plurality of trial samples 6 of the filtration module were prepared similarly to trial sample 1 except that the average effective length (C) of the plurality of hollow fiber membranes when wet was 2140mm and the average interval (a) between the pair of holding members was 2040 mm.

< trial sample 7>

A plurality of trial samples 7 of the filtration module were prepared similarly to trial sample 6 except that the average effective length (C) of the plurality of hollow fiber membranes when wet was 2220 mm.

< trial sample 8>

A plurality of trial samples 8 of the filtration module were prepared similarly to trial sample 6, except that the average effective length (C) of the plurality of hollow fiber membranes when wet was 2300 mm.

< test >

The filtration modules of trial samples 1 to 8 were held by the support so that the average interval (B) between the holding regions of the respective hollow fiber membranes was 25mm, and then the filtration modules were incorporated into the respective filtration apparatuses. Next, the following test procedures were performed: the hollow fiber membrane was immersed in a container storing liquid and the liquid was continuously filtered for 4 weeks while supplying bubbles from below. Then, it was confirmed whether entanglement occurred between the hollow fiber membranes. As a result, entanglement between the hollow fiber membranes occurred in trial samples 4, 5, and 8.

The filtration module was further dried in the air for 4 weeks after the test operation, and then the condition of the hollow fiber membrane was confirmed. As a result, it was confirmed that breakage of the hollow fiber membrane occurred only in the trial sample 1.

Table 1 below shows the pilot conditions for pilot samples 1 to 8 of the filtration module and (C)²-A²)^0.5The value of/2B.

[ Table 1]

As a result, it was confirmed that entanglement of the hollow fiber membrane can be prevented and removal of suspended matter by air bubbles can be promoted, and (C) can be optimized²-A²)^0.5The value of/2B prevents damage to the hollow fiber membrane during drying.

Description of the reference numerals

1 filtration device

2 Filter module

3 support piece

4 gas supply module

5 discharge mechanism

6 hollow fiber membrane

7 Upper holding Member

7a hollow shell

7b resin composition

7c discharge nozzle

8 lower holding member

9 gas supply conduit

9a bubble discharge port

10 collecting pipe

11 suction pump

Average interval between A holding members in vertical direction

Average interval between B holding areas

Average effective length of hollow fiber membrane when wet

G bubbles

Average length in long side direction of La holding region

Average length in short side direction of Lb holding region

R holding region

W filtering container

Claims

1. A filtration apparatus comprising:

a plurality of filtration modules, each of which includes a plurality of hollow fiber membranes arranged in an up-down direction and a pair of holding members having holding regions for fixing top ends and bottom ends of the plurality of hollow fiber membranes;

a support for holding the plurality of filter modules such that the plurality of filter modules are arranged in parallel at equal intervals; and

one or more gas supply modules for supplying gas bubbles from below the plurality of filtration modules,

wherein the plurality of hollow fiber membranes contain polytetrafluoroethylene as a main component,

an average interval in the up-down direction between the pair of holding members of the plurality of filtration modules is represented by a, an average interval between the holding regions of the plurality of hollow fiber membranes of adjacent filtration modules is represented by B, and an average effective length when wetted of the plurality of hollow fiber membranes exposed between the pair of holding members is represented by C, then

(C²-A²)^0.5The value of/2B is greater than or equal to 10 and less than or equal to 20.

2. The filtration apparatus according to claim 1, wherein an average effective length of the plurality of hollow fiber membranes exposed between the pair of holding members at the time of drying is larger than an average interval a in an up-down direction between the pair of holding members.

3. The filter apparatus according to claim 1 or 2, wherein an average interval a in the up-down direction between the pair of holding members is greater than or equal to 2.0m and less than or equal to 4.0 m.

4. A filter device according to any one of claims 1 to 3, wherein the average spacing B between the holding areas is greater than or equal to 15mm and less than or equal to 50 mm.

5. The filtration apparatus of any one of claims 1 to 4, wherein an average outer diameter of the plurality of hollow fiber membranes is greater than or equal to 1.5mm and less than or equal to 4.0 mm.