JP2022184640A - Hollow fiber membrane module - Google Patents

Abstract

To provide a hollow fiber membrane module capable of suppressing tangling, damage and the like of a hollow fiber membrane while effectively removing a floating pollutant stuck on the surface of the hollow fiber membrane in a bubbling step.SOLUTION: A hollow fiber membrane module 10 comprises: a housing 13 where a fixing member 3 is fixed inside and an internal space S1 is formed; a plurality of hollow fiber membrane bundles 15 which has a plurality of hollow fiber membranes 14 respectively and which is arranged in the internal space S1 in a state that the upper edge 14B of the hollow fiber membrane 14 is fixed to the fixing member 3; a gas supply part 2 supplying a gas to clean the hollow fiber membrane bundle 15 into the internal space S1; and a suppression member 100 individually arranged at the respective plurality of hollow fiber membrane bundles 15. The suppression member 100 suppresses the splashing of the lower edges 14A of the plurality of hollow fiber membranes 14 while allowing the oscillation of the plurality of hollow fiber membranes 14 by the gas supplied into the internal space S1 from the gas supply part 2 in the corresponding hollow fiber membrane bundle 15.SELECTED DRAWING: Figure 7

Description

The present invention relates to a hollow fiber membrane module having a plurality of hollow fiber membranes.

2. Description of the Related Art Conventionally, in water treatment for removing impurities in water, a hollow fiber membrane module having a plurality of bundled hollow fiber membranes has been used. In the filtration process of water treatment, raw water (water before filtration) is supplied into the module through the raw water inlet provided in the hollow fiber membrane module, and filtered water that has passed through the membrane is sent out of the module through the filtered water outlet provided in the module. discharged to

In a hollow fiber membrane module, when a filtration process for water treatment is performed, substances removed from water (suspended solids (SS)) are deposited on the membrane surface. Thus, efficient removal of suspended contaminants deposited on the membrane surface is one of the important issues.

Generally, removal of suspended contaminants is performed by so-called backwashing (back pressure washing). In the backwash process, a fluid flow is formed in the module in the opposite direction to the filtration process in order to float suspended contaminants adhering to the membrane surface from the membrane. That is, a fluid such as gas or liquid is supplied into the module through the filtered water outlet, and the fluid that has passed through the membrane from the inside to the outside is discharged out of the module through the raw water inlet.

In this way, the suspended contaminants that have partially floated from the membrane surface due to the backwashing process are then peeled off from the membrane surface by the bubbling process. In this bubbling process, the cleaning gas is supplied while the module is filled with water, and the membrane is shaken by the bubbles of the supplied cleaning gas, causing the suspended contaminants on the surface of the membrane to peel off.

In the bubbling step, it is necessary to strongly agitate the hollow fiber membrane in order to more effectively remove suspended contaminants deposited on the membrane surface. On the other hand, if excessive rocking occurs, scratching due to contact between hollow fiber membranes, breakage of hollow fiber membranes in the vicinity of fixed portions, entanglement of hollow fiber membranes, and the like occur, making stable operation difficult. Patent Literature 1 listed below discloses a hollow fiber membrane module having a configuration for appropriately rocking the hollow fiber membranes in the bubbling process.

In the hollow fiber membrane module of Patent Document 1 below, a net-like object is provided so as to cover the entire bundle of hollow fiber membranes, in which a plurality of hollow fiber membranes are fixed in a bundle shape at the upper end.

JP-A-9-262441

In Patent Document 1, all the hollow fiber membranes that make up the hollow fiber membrane module are bundled as one hollow fiber membrane bundle, and this one hollow fiber membrane bundle is entirely covered with a net-like material. In this case, since the oscillation of all the hollow fiber membranes is regulated by the same net-like substance in the bubbling process, the suspended contaminants adhering to the membrane surface cannot be effectively removed. Further, in a structure in which the entire bundle of hollow fiber membranes is covered with a net-like material, there is a possibility that the lower ends of the hollow fiber membranes may enter the mesh of the net-like material due to rocking during the bubbling process. In this case, the hollow fiber membranes become entangled with the net-like material, resulting in problems such as damage to the hollow fiber membranes.

The present invention has been made in view of the above problems, and its purpose is to effectively remove suspended contaminants attached to the membrane surface of the hollow fiber membrane in the bubbling process, while preventing entanglement and damage of the hollow fiber membrane. It is an object of the present invention to provide a hollow fiber membrane module capable of suppressing the

A hollow fiber membrane module according to one aspect of the present invention includes a housing in which a fixing member is fixed and which forms an internal space, and a plurality of hollow fiber membranes, respectively, the upper ends of the plurality of hollow fiber membranes a plurality of hollow fiber membrane bundles arranged in the internal space while being fixed to a fixing member; a gas supply section for supplying gas for cleaning the plurality of hollow fiber membrane bundles into the internal space; and a suppressing member provided individually for each of the hollow fiber membrane bundles. Each of the suppressing members allows the plurality of hollow fiber membranes in the corresponding hollow fiber membrane bundle to oscillate by the gas supplied from the gas supply unit into the internal space, while allowing the plurality of hollow fiber membranes to oscillate. It is configured to prevent the lower end of the hollow fiber membrane from rising.

According to this hollow fiber membrane module, the hollow fiber membranes constituting the hollow fiber membrane module are divided into a plurality of hollow fiber membrane bundles with their upper ends fixed to a fixing member. A suppressing member is provided for each individually. Thereby, each hollow fiber membrane bundle becomes independent from each other by the suppressing member. Therefore, in the bubbling process according to the supply of the cleaning gas from the gas supply unit, the plurality of hollow fiber membranes oscillate within the bundle of hollow fiber membranes that are independent of each other. As a result, suspended contaminants adhering to the membrane surface are peeled off, but at this time, each hollow fiber membrane bundle is in a state of being independent from each other by the suppressing member, so that a plurality of hollow fibers in each hollow fiber membrane bundle Suspended contaminants peeled off from the membrane surface of the membrane can be discharged through the hollow fiber membrane bundles. This makes it possible to effectively remove suspended contaminants adhering to the surface of the hollow fiber membranes in each hollow fiber membrane bundle. Moreover, the suppression member allows the hollow fiber membrane bundles to become independent from each other, thereby suppressing interference between the hollow fiber membranes belonging to different hollow fiber membrane bundles. As a result, it is possible to suppress the entanglement of the hollow fiber membranes between the bundles of the hollow fiber membranes, and to suppress the accompanying damage to the hollow fiber membranes.

In addition, the suppressing member that separates each hollow fiber membrane bundle prevents the lower ends of the plurality of hollow fiber membranes from rising while allowing the plurality of hollow fiber membranes to oscillate in the hollow fiber membrane bundle. configured to suppress. In this way, the suppressing member suppresses the lower ends of the plurality of hollow fiber membranes from rising in the hollow fiber membrane bundle, thereby restricting excessive movement of the plurality of hollow fiber membranes in the hollow fiber membrane bundle. Therefore, excessive interference between hollow fiber membranes, such as entanglement of hollow fiber membranes belonging to the same hollow fiber membrane bundle, can be suppressed, and accompanying damage to the hollow fiber membranes can be suppressed.

In the above hollow fiber membrane module, each of the suppressing members may have a plurality of meshes and may be configured by a mesh body extending vertically so as to cover the side surface of the corresponding hollow fiber membrane bundle. In this case, each of the lower ends of the suppressing member can suppress the lower ends of the plurality of hollow fiber membranes swinging in the corresponding hollow fiber membrane bundle from rising, and the lower ends of the plurality of hollow fiber membranes can be prevented from rising up. It is located at a position where it can be suppressed from entering the mesh.

In this aspect, the lower end of the suppressing member configured by the net-like body covering the side surface of the hollow fiber membrane bundle can suppress the lower ends of the plurality of hollow fiber membranes swinging in the hollow fiber membrane bundle from rising, The lower ends of the plurality of hollow fiber membranes are located at positions that can prevent them from entering the mesh. The suppressing member suppresses the lower ends of the plurality of hollow fiber membranes from rising in the hollow fiber membrane bundle, thereby suppressing the entanglement of the hollow fiber membranes in the hollow fiber membrane bundle. Furthermore, by setting the position of the lower end of the suppressing member so as to prevent the lower end of the hollow fiber membrane from entering the mesh of the suppressing member, it is possible to restrict the entanglement of the hollow fiber membrane with the suppressing member. As a result, damage to the hollow fiber membrane can be suppressed.

In the hollow fiber membrane module described above, the upper ends of the suppressing members are fixed to the fixing member, and the vertical lengths of the suppressing members are set to satisfy the following formula (1). may be
0.7≦L1/L2≦1.0 (1)

In the above formula (1), "L1" indicates the vertical length of the suppressing member, and "L2" indicates the effective length of the hollow fiber membrane.

In this aspect, the length in the vertical direction of the suppressing member constituted by the net-like body covering the side surface of the hollow fiber membrane bundle is set so as to satisfy the above formula (1). By setting the length of the suppressing member so as to satisfy "0.7 ≤ L1/L2" on the left side of the above formula (1), the lower ends of the suppressing member are prevented from rising up. can be placed wherever possible. On the other hand, the length of the suppressing member is set so as to satisfy "L1/L2≤1.0" on the right side of the above equation (1), so that the lower end of the suppressing member is the lower end of the plurality of hollow fiber membranes. can be located at a position where it can be suppressed from entering the mesh of the

In the above hollow fiber membrane module, each of the suppressing members may have a function of partitioning the hollow fiber membrane bundles so that a gap is formed between the plurality of hollow fiber membrane bundles.

In this aspect, since a gap is formed between the hollow fiber membrane bundles by the suppressing member, the suspended contaminants peeled off in accordance with the oscillation of the plurality of hollow fiber membranes in each hollow fiber membrane bundle in the bubbling step. can be discharged through the gaps between each hollow fiber membrane bundle. As a result, the effect of removing suspended contaminants adhering to the membrane surface of the hollow fiber membrane can be further enhanced.

In the above-described hollow fiber membrane module, the gas supply section is arranged at a position below the hollow fiber membrane bundle, has a shape that expands in the radial direction of the hollow fiber membrane bundle, and is spaced apart in the radial direction. A configuration including an air diffusion member in which a plurality of air diffusion vent holes are formed at intervals may be employed. In this case, the air diffusion member has a shape that expands in the radial direction of the hollow fiber membrane bundle, and has a plate-like body portion in which a plurality of air diffusion holes are formed at intervals in the radial direction. , which has a cylindrical shape with one end connected to the lower surface of the main body and a gas inlet formed on the other end side, for guiding the gas accommodated in the cylinder to the air diffusion vent hole. a gas receiving portion having a dispersion hole formed therein.

In the hollow fiber membrane module described above, the gas receiving portion may have a shape in which the inner diameter increases from the one end toward the other end.

In the hollow fiber membrane module described above, the air diffusion holes are arranged on a plurality of circles spaced apart in the radial direction in the main body, and the air diffusion holes are arranged on each circumference. The number of pores may be a multiple of the number of hollow fiber membrane bundles.

As described above, according to the present invention, a hollow fiber membrane capable of suppressing entanglement and damage of the hollow fiber membrane while effectively removing suspended contaminants attached to the membrane surface of the hollow fiber membrane in the bubbling process. Modules can be provided.

It is a mimetic diagram showing the composition of the filtering device concerning the embodiment of the present invention. 1 is a diagram showing the configuration of a hollow fiber membrane module according to a first embodiment of the present invention; FIG. FIG. 3 is a diagram showing a planar structure of an air diffusion member provided in a hollow fiber membrane module; FIG. 4 is a diagram showing a cross-sectional structure of the diffusion member along line IV-IV in FIG. 3; FIG. 3 is a diagram showing a cross-sectional structure of a water conduit along line segment VV in FIG. 2; 3 is an enlarged view of the water conduit in area VI in FIG. 2; FIG. FIG. 3 is a perspective view showing a state in which a suppressing member is provided for each hollow fiber membrane bundle in the hollow fiber membrane module. FIG. 3 is a top view of a state in which a suppressing member is provided for each hollow fiber membrane bundle in a hollow fiber membrane module. It is a figure which shows the basic operation program of a filtration apparatus. FIG. 8 is a perspective view showing a state in which a suppressing member is provided for each hollow fiber membrane bundle in the hollow fiber membrane module according to the second embodiment of the present invention; FIG. 11 is a perspective view showing a state in which a suppressing member is provided for each hollow fiber membrane bundle in a hollow fiber membrane module according to a third embodiment of the present invention; FIG. 11 is a perspective view showing a state in which a suppressing member is provided for each hollow fiber membrane bundle in a hollow fiber membrane module according to a fourth embodiment of the present invention; FIG. 11 is a perspective view showing a state in which a suppressing member is provided for each hollow fiber membrane bundle in a hollow fiber membrane module according to a fifth embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

(First embodiment)
[Filtration device, hollow fiber membrane module]
First, the configuration of a filtration device 1 having a hollow fiber membrane module 10 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a schematic diagram showing the configuration of a filtering device 1. As shown in FIG. FIG. 2 is a schematic diagram showing the configuration of the hollow fiber membrane module 10. As shown in FIG.

The filtration device 1 includes an external pressure filtration type hollow fiber membrane module 10, a liquid transfer pump 20, an air compressor 30, a pipe connecting these components, an open/close valve provided in the pipe, and a control device 40. . The hollow fiber membrane module 10 is an external pressure filtration module that supplies a stock solution to the outer surface side of the hollow fiber membrane and extracts the filtrate from the inner surface side.

As shown in FIG. 2, the hollow fiber membrane module 10 includes a housing 13 in which a fixing member 3 is fixed and which forms an internal space S1, and a plurality of hollow fiber membrane bundles 15 arranged in the internal space S1. , a water conduit (pipe member) 5 for introducing raw water into the internal space S1, and a gas supply unit for supplying gas (cleaning gas) for cleaning the plurality of hollow fiber membrane bundles 15 into the internal space S1. 2 and suppressing members 100 provided individually for each of the plurality of hollow fiber membrane bundles 15 .

Each of the plurality of hollow fiber membrane bundles 15 has a plurality of hollow fiber membranes 14, is fixed to the fixing member 3 in a state in which the upper ends 14B of the plurality of hollow fiber membranes 14 are open, and the lower ends of the plurality of hollow fiber membranes 14 are 14A is a one-end free type in which each wire is sealed without being fixed. The fixing member 3 converges and fixes the upper ends 14B of the plurality of hollow fiber membranes 14 for each hollow fiber membrane bundle 15 . The fixing member 3 liquid-tightly partitions the space in the housing 13 into an internal space S1 on the raw water side and a space S2 on the filtrate side in order to allow the hollow fiber membrane 14 to function as a filtration membrane. A thermosetting resin such as an epoxy resin, an unsaturated polyester resin, or a polyurethane resin is used for the fixing member 3 . Methods for adhering each hollow fiber membrane bundle 15 and the fixing member 3 include a centrifugal adhesion method and a stationary adhesion method.

Various materials can be used as the material of the hollow fiber membrane 14, and the material is not particularly limited. For example, polyethylene, polypropylene, polyacrylonitrile, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, polytetrafluoroethylene, polyvinyl fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoro It preferably contains at least one selected from the group consisting of alkyl vinyl ether copolymers, chlorotrifluoroethylene-ethylene copolymers, polyvinylidene fluoride, polysulfone, cellulose acetate, polyvinyl alcohol and polyethersulfone. Polyvinylidene fluoride (PVDF) is more preferable from the viewpoint of chemical resistance.

The hollow fiber membrane module 10 is of an external pressure filtration type, and may be of an external pressure dead end filtration type or an external pressure circulation filtration type depending on the conditions of the membrane separation treatment and required performance. From the standpoint of membrane life, the external pressure circulation filtration system is preferred because the surface of the filtration membrane can be washed at the same time, and the external pressure dead end filtration system is preferred from the standpoints of facility simplicity, installation costs, and operating costs.

In the hollow fiber membrane module 10, as the total number of the hollow fiber membranes 14 constituting each hollow fiber membrane bundle 15 increases, the membrane area per module increases, so that it can be operated at a high filtration flow rate. However, on the other hand, the discharge efficiency of suspended contaminants during washing decreases. Therefore, the membrane filling rate 100πndi ² /4S (%) calculated from the outer diameter di (m) of the hollow fiber membranes 14, the total number n (number) of the hollow fiber membranes 14, and the cross-sectional area S (m ² ) of the housing 13 is preferably 10 to 60%, more preferably 20 to 50%.

The housing 13 has a cylindrical shape with an upper surface 13A, a lower surface 13C, and a side surface 13B connecting them. The housing 13 has an internal space S1 in which a plurality of hollow fiber membrane bundles 15 are accommodated. , and a lower space S12 in which the portion below the center in the longitudinal direction of the hollow fiber membrane 14 is located.

A filtrate pipe 51 for extracting filtrate is connected to the upper surface 13A of the housing 13, and the filtrate pipe 51 is provided with a filtrate outlet 52 and a filtrate-side gas inlet 53. As shown in FIG. Directly below the fixing member 3 on the side surface 13B is provided a gas vent 11 for discharging the gas in the internal space S1 to the outside of the system. The gas vent 11 is an opening of the upper space S11. A drain port 12 for discharging the liquid in the internal space S1 to the outside of the system is provided on the side surface 13B directly above the lower surface 13C. A diffuser gas inlet 7 for supplying gas into the internal space S1 is provided near the center of the lower surface 13C.

As shown in FIG. 1, a gas vent pipe 61 is connected to the gas vent port 11, through which the gas in the housing 13 is discharged to the outside of the system. A gas discharge pipe 61 is provided with a gas discharge port valve 62, and gas is discharged from the housing 13 by opening the valve. A drain pipe 41 is connected to the drain port 12, through which the liquid in the housing 13 is discharged to the outside of the system. The drain pipe 41 is provided with an undiluted liquid outlet valve 42, and the liquid is discharged from the housing 13 by opening the valve.

As a material for the housing 13, SUS, modified PPE, polyvinyl chloride, polysulfone, polycarbonate, polyolefin, ABS resin, or the like is used. A so-called integrated module may be configured by adhesively fixing the fixing member 3 to the inner surface of the housing 13 . Further, an O-ring, a packing, or the like may be attached to the outer peripheral portion of the fixing member 3, and the fixing member 3 may be attached to the housing 13 in a detachable and liquid-tight manner. In this case, the housing 13 can be used repeatedly by removing the fixing member 3 and replacing each hollow fiber membrane bundle 15 .

As shown in FIG. 2 , the water conduit 5 is arranged in a posture extending through the center of the lower surface 13</b>C of the housing 13 and toward the upper surface 13</b>A, and the upper end is connected to the fixing member 3 . The water conduit 5 is provided with an undiluted solution inlet 9 on the lower end side and a water conduit gas inlet 8 on the side surface. According to the water conduit 5, only the unfiltered raw water introduced from the raw liquid inlet 9 can be supplied into the housing 13, and only the gas introduced from the water conduit gas inlet 8 can be supplied into the housing 13. and both raw water and gas can be fed into the housing 13 . The water conduit 5 constitutes a part of the gas supply section 2 .

The gas supply unit 2 has the water conduit 5 and the air diffusion member 4 described above. The air diffusion member 4 is a member for dispersing the gas supplied into the housing 13 from the air diffusion gas inlet 7 provided on the lower surface 13C of the housing 13 so as to spread in the radial direction of each hollow fiber membrane bundle 15. is. The air diffusion member 4 is arranged below the plurality of hollow fiber membrane bundles 15, and the water conduit 5 penetrates through the central portion thereof. Detailed structures of the water conduit 5 and the air diffusion member 4 will be described later.

The suppression member 100 is individually provided for each of the plurality of hollow fiber membrane bundles 15 . Each of the suppression members 100 is a member that controls the movement of the plurality of hollow fiber membranes 14 within the corresponding hollow fiber membrane bundle 15 in a state in which gas is supplied to the internal space S1 of the housing 13 by the gas supply unit 2. be. A detailed structure of the suppression member 100 will be described later.

As shown in FIG. 1 , the liquid feed pump 20 is connected to the raw liquid inlet 9 of the water conduit 5 via a raw liquid introduction pipe 21 . The undiluted solution introduction pipe 21 is provided with an undiluted solution introduction valve 22 for switching between flow and blockage of the raw water in the pipe. The liquid feed pump 20 supplies raw water into the water conduit 5 via the raw liquid introduction pipe 21 .

The air compressor 30 is connected to the filtrate-side gas inlet 53 through the first gas introduction pipe 31, to the diffusion gas inlet 7 through the second gas introduction pipe 32, and to the third gas introduction pipe 33. is connected to the conduit gas inlet 8 . The first gas introduction pipe 31 is provided with a first gas introduction valve 34 for switching between the flow and cutoff of the gas in the pipe, and the second and third gas introduction pipes 32 and 33 are similarly provided with the second and third gas introduction pipes. Valves 35, 36 are provided. Thus, in this embodiment, the third gas introduction pipe 33 and the third gas introduction valve 36 as gas supply means for the water conduit 5, the second gas introduction pipe 32 as gas supply means for the diffuser member 4 and A second gas introduction valve 35 is provided separately.

The control device 40 controls driving of the liquid-sending pump 20 and the air compressor 30, and controls opening/closing operations of each valve. The control device 40 is configured by, for example, a personal computer. The control device 40 includes a storage unit that stores sequence information for each step (water filling, filtration, backwashing, bubbling, drainage, etc.) that is sequentially executed in the filtration process, and a drive and valve operation for each device according to the sequence information. and a control unit for controlling opening and closing.

[Air diffusion member, water pipe]
Next, detailed structures of the diffuser member 4 and the water conduit 5 will be described with reference to FIGS. 2 to 5. FIG. FIG. 3 shows the planar structure of the diffuser member 4 . FIG. 4 shows a cross-sectional structure of the diffuser member 4 along line IV-IV in FIG. FIG. 5 shows the cross-sectional structure of the water conduit 5 along the line segment VV in FIG. In the hollow fiber membrane module 10, the gas supply unit 2 that supplies while dispersing the gas (for example, air) for cleaning the hollow fiber membranes 14 into the internal space S1 of the housing 13 has an air diffusion member 4 and a water conduit 5. is doing.

The diffuser member 4 is arranged below the lower ends 14A of the hollow fiber membranes 14 constituting each hollow fiber membrane bundle 15 . The diffuser member 4 has a shape expanding in the radial direction of each hollow fiber membrane bundle 15 . A plurality of air diffusion holes 43 for dispersing gas in the housing 13 are formed in the air diffusion member 4 at intervals in the radial direction.

The diffuser member 4 includes a disk-shaped main body portion 44 in which a plurality of air diffusion holes 43 are formed, a peripheral wall portion 47 connected to the peripheral edge portion of the main body portion 44, and a lower surface of the main body portion 44. and a cylindrical gas receiving portion 45, which are integrally formed.

The air diffuser 43 is formed so as to pass through the main body 44 in the thickness direction. The air diffusion holes 43 are formed at intervals in the radial direction and the circumferential direction of the main body 44 , and some of them are located radially outside the respective hollow fiber membrane bundles 15 . Thereby, the gas can be dispersed in a wide range in the radial direction with respect to each hollow fiber membrane bundle 15 . In addition, as shown in FIG. 3 , the air diffusion holes 43 are arranged on a plurality of circles spaced apart in the radial direction in the body portion 44 . In this case, the number of air diffusion holes 43 on each circumference is set to be a multiple of the number of hollow fiber membrane bundles 15 . Specifically, the number of air diffusion holes 43 on each circumference is set so that the number of air diffusion holes 43 corresponding to each hollow fiber membrane bundle 15 is the same. It is set to satisfy that it is a multiple of the number. A through hole 44A through which the water conduit 5 penetrates is formed in the center of the body portion 44 . Note that the main body portion 44 is not limited to the disc-shaped one shown in FIG. 3, and may be of various shapes.

The gas receiving portion 45 is a portion for temporarily accommodating the gas supplied into the housing 13 from the diffusion gas inlet 7 . The gas receiving portion 45 has a cylindrical shape, an upper end (one end) of which is connected to the lower surface of the main body portion 44, and a gas receiving port 45A formed on a lower end (the other end) side. In this embodiment, the gas receiving portion 45 is configured such that the inner diameter is substantially constant from the upper end to the lower end. In addition, the gas receiving portion 45 may be configured to have a shape in which the inner diameter increases from the upper end to the lower end. The gas receiving portion 45 has an inner diameter larger than the outer diameter of the water conduit 5 and accommodates the gas in the gap between it and the outer peripheral surface of the water conduit 5 .

The gas receiving portion 45 is positioned radially outward of the diffusion gas inlet 7, so that the gas supplied from the diffusion gas inlet 7 into the housing 13 can be accommodated in the cylinder. Further, as shown in FIG. 2, a gap is formed between the lower end of the gas receiving portion 45 and the lower wall of the housing 13, and the liquid in the housing 13 can flow through the gap. As a result, it is possible to prevent liquid pooling in the lower portion of the housing 13 .

A plurality of dispersion holes 46 are formed at intervals in the circumferential direction in the upper end portion of the gas receiving portion 45 . The dispersion hole 46 is formed so as to penetrate the gas receiving portion 45 . The dispersion holes 46 allow the gas contained in the gas receiving portion 45 to escape radially outward from the gas receiving portion 45 and be guided to the air diffusion vent hole 43 . The distribution holes 46 may be formed at equal intervals in the circumferential direction, or may be formed at different intervals.

The peripheral wall portion 47 has a tubular shape extending downward from the peripheral portion of the main body portion 44 . The peripheral wall portion 47 can prevent the gas released from the dispersion hole 46 to the outside of the gas receiving portion 45 from spreading outside the main body portion 44 . As a result, the gas can be retained on the lower surface of the main body portion 44 before the gas is dispersed from the air diffusion holes 43 .

According to the air diffusion member 4, in the bubbling process, the gas supplied from the air diffusion gas inlet 7 into the housing 13 is temporarily accommodated in the gas receiving portion 45, released to the outside through the dispersion holes 46, and then diffused. It can be distributed to the lower space S12 from the ventilation hole 43 for ventilation. That is, in the present embodiment, the air diffusion vent 43 functions as a lower gas supply portion that disperses the gas in the housing 13 at a position below the lower space S12.

The water conduit 5 is arranged to extend vertically through the center of the housing 13 . The water conduit 5 has a cylindrical shape, but is not particularly limited. As shown in FIG. 2, the water conduit 5 passes through the air diffusion member 4 (main body portion 44), and its lower end is fixed to the undiluted solution introduction pipe 21 (FIG. 1) via an arbitrary sealing member (not shown). there is In addition, the method of fixing the water conduit 5 is not limited to this, and a separate pipe that protrudes upward from the upper surface of the main body 44 is provided, and the water conduit 5 is attached to the main body so that the projecting portion is located inside the water conduit 5. It may be placed on top of 44 .

A plurality of pipe ventilation holes 54 are formed at intervals over the entire longitudinal direction (vertical direction) in a portion of the water conduit 5 that protrudes upward from the upper surface of the main body portion 44 . More specifically, a plurality of pipe vent holes 54 are formed at intervals in the portion located in the upper space S11 of the water conduit 5, and a plurality of pipe vent holes 54 are formed in a portion located in the lower space S12. formed with a gap. Through these pipe vent holes 54 , bubbling gas (cleaning gas) can be supplied into the housing 13 , and raw water filtered by the hollow fiber membranes 14 can be supplied into the housing 13 . The pipe vent holes 54 may be formed at equal intervals in the longitudinal direction, or may be formed at different intervals. Further, the pipe ventilation hole 54 is circular, but is not particularly limited.

The plurality of pipe ventilation holes 54 are formed with the same size in the longitudinal direction of the water conduit 5 . The inner diameter of the pipe vent hole 54 is preferably designed to be 30 mm or less in order to enhance the bubbling effect. In addition, the inner diameter of the pipe ventilation hole 54 is preferably designed so that the total discharge flow rate of the raw water from each hole is 4 m/s or less, and 3 m/s or less, in order to reduce the pressure loss during water flow. More preferably, it is designed to be

As shown in FIG. 2, the pipe vent hole 54A formed at the top of the water conduit 5 is located above the lower surface 11A of the gas vent 11, and the second pipe vent hole 54B from the top is located above the lower surface 11A. It is located below 11A. In other words, the pipe vent holes 54A and 54B are formed in the water conduit 5 at positions sandwiching the lower surface 11A of the gas vent 11 in the vertical direction.

As shown in FIG. 5 , four pipe ventilation holes 54 are formed at equal intervals in the circumferential direction of the water conduit 5 . In this embodiment, four pipe ventilation holes 54 are formed at intervals of 90° in both the portion located in the upper space S11 and the portion located in the lower space S12. Not limited. Further, the number of pipe ventilation holes 54 and the intervals in the circumferential direction may be different between the portion located in the upper space S11 and the portion located in the lower space S12.

FIG. 6 is an enlarged view of the water conduit 5 in area VI in FIG. The porosity of the pipe ventilation holes 54 in the water conduit 5 can be defined as follows. As shown in the shaded area in FIG. 6, S1 is the area of the outer peripheral surface of the water conduit 5 in the range from the intermediate height position of the uppermost pipe ventilation hole 54A to the intermediate height position of the lower pipe ventilation hole 54B. , the opening ratio of the pipe vent holes can be defined as S2/S1×100, where S2 is the total hole area of all the pipe vent holes 54A and 54B formed on the outer peripheral surface of the range. In the present embodiment, the porosity is preferably designed to be 1% or more and 20% or less.

According to the water conduit 5, the raw water can be supplied into the housing 13 from the pipe ventilation hole 54, and the gas introduced from the water conduit gas inlet 8 is raised by buoyancy, and the pipe ventilation holes 54A and 54B located in the upper space S11. can be dispersed within the housing 13 from. That is, in the present embodiment, the pipe vents 54A and 54B function as upper gas supply portions that disperse the gas within the housing 13 at the position of the upper space S11.

The length of the water conduit 5 inserted into the housing 13 is preferably 1 to 2 times the length of the hollow fiber membranes 14 so as not to make the hollow fiber membrane module 10 bulky. More preferably 0.5 times.

The inner diameter of the water conduit 5 is preferably designed so that the flux during water flow is 4 m/s or less, more preferably 3 m/s or less, in order to reduce pressure loss during water flow. is more preferable.

[Suppression member]
Next, the detailed structure of the suppressing member 100 will be described with reference to FIGS. 7 and 8 in addition to FIG. In the hollow fiber membrane module 10 according to this embodiment, the hollow fiber membranes 14 constituting the hollow fiber membrane module 10 are divided into a plurality of hollow fiber membrane bundles 15 with the upper ends 14B fixed to the fixing member 3 . The plurality of hollow fiber membrane bundles 15 are arranged in the inner space S1 of the housing 13 at equal intervals in the circumferential direction so as to surround the water conduit 5 . In the example shown in FIG. 8, six hollow fiber membrane bundles 15 are arranged so as to surround the water conduit 5, but the number of hollow fiber membrane bundles 15 arranged is not particularly limited as long as it is two or more.

The suppression member 100 is individually provided for each of the plurality of hollow fiber membrane bundles 15 . Thereby, each hollow fiber membrane bundle 15 becomes independent from each other by the suppressing member 100 . Therefore, in the bubbling step in which the cleaning gas is supplied to the internal space S1 of the housing 13 by the gas supply unit 2, the plurality of hollow fiber membranes 14 are oscillated within the hollow fiber membrane bundle 15 in a mutually independent state. .

A plurality of hollow fiber membranes 14 oscillate within each hollow fiber membrane bundle 15, thereby peeling off suspended contaminants adhering to the membrane surface. Because of this state, the suspended contaminants peeled off from the membrane surfaces of the plurality of hollow fiber membranes 14 in each hollow fiber membrane bundle 15 can be discharged through the hollow fiber membrane bundles 15 . As a result, suspended contaminants adhering to the surface of the hollow fiber membranes 14 in each hollow fiber membrane bundle 15 can be effectively removed. Moreover, the suppression member 100 allows the hollow fiber membrane bundles 15 to become independent from each other, thereby suppressing interference between the hollow fiber membranes 14 belonging to different hollow fiber membrane bundles 15 . As a result, it is possible to prevent the hollow fiber membranes 14 from entangling between the hollow fiber membrane bundles 15 and to prevent the hollow fiber membranes 14 from being damaged.

In addition, the suppression member 100 that makes each hollow fiber membrane bundle 15 independent allows the plurality of hollow fiber membranes 14 to oscillate in the hollow fiber membrane bundle 15, while allowing the plurality of hollow fiber membranes 14 It is configured to prevent the lower end 14A from rising. That is, bending of the hollow fiber membranes 14 to the extent that the lower ends 14A of the hollow fiber membranes 14 are located above the lower ends 100A of the suppressing members 100 is suppressed. The suppressing member 100 suppresses the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 from rising, thereby restricting excessive movement of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 . Therefore, excessive interference between the hollow fiber membranes 14, such as entanglement of the hollow fiber membranes 14 belonging to the same hollow fiber membrane bundle 15, can be suppressed, and accompanying damage to the hollow fiber membranes 14 can be suppressed. can.

In addition, each of the suppressing members 100 has a function of partitioning the hollow fiber membrane bundles 15 so that a gap is formed between the plurality of hollow fiber membrane bundles 15 . Since the gaps are formed between the hollow fiber membrane bundles 15 by the suppressing member 100 in this manner, the plurality of hollow fiber membranes 14 are peeled off in response to the oscillation of the plurality of hollow fiber membranes 14 within the hollow fiber membrane bundles 15 in the bubbling process. Suspended contaminants can be discharged through the gaps between the hollow fiber membrane bundles 15 . As a result, the effect of removing suspended contaminants adhering to the membrane surface of the hollow fiber membrane 14 can be further enhanced.

As shown in FIG. 7 , each of the suppressing members 100 has a plurality of meshes 101 and is composed of a mesh body extending vertically so as to cover the side surface of the corresponding hollow fiber membrane bundle 15 . In this case, various materials can be used as the material of the suppressing member 100, and the material is not particularly limited. Examples include polyethylene and polypropylene. The suppressing member 100 formed of a mesh has elasticity corresponding to deformation of the shape of the mesh 101 . When the plurality of hollow fiber membranes 14 oscillate within the hollow fiber membrane bundle 15 in the bubbling process, the suppressing member 100 deforms the shape of the mesh 101 and expands and contracts, so that the plurality of hollow fiber membranes 14 are appropriately swayed. oscillate.

Each of the lower ends 100A of the suppressing member 100 constituted by a mesh-like body can suppress the rising of the lower ends 14A of the plurality of hollow fiber membranes 14 swinging within the corresponding hollow fiber membrane bundle 15, and the plurality of hollow fiber membranes. The lower end 14A of the mesh 14 is positioned within the lower end proper range that can prevent the mesh 101 from entering. The appropriate lower end range is a range in which the lower end 100A of the suppressing member 100 is spaced downward from the upper end 14B of the hollow fiber membrane 14 within a range of 0.7 to 1.0 times the effective length L2 of the hollow fiber membrane 14. be. The effective length L2 of the hollow fiber membrane 14 is the vertical length of the portion of the hollow fiber membrane 14 exposed to the internal space S1 of the housing 13 .

By suppressing the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 to which the suppressing member 100 corresponds, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 can be suppressed from being entangled with each other. can. Furthermore, by setting the position of the lower end 100A of the suppressing member 100 so that the lower end 14A of the hollow fiber membrane 14 can be suppressed from entering the mesh 101 of the suppressing member 100, the hollow fiber membrane 14 can be entangled with the suppressing member 100. can be regulated. As a result, damage to the hollow fiber membrane 14 can be suppressed.

In the present embodiment, the upper ends 100B of the suppressing members 100 formed of a mesh-like body are respectively fixed to the upper ends 14B of the plurality of hollow fiber membranes 14 in the corresponding hollow fiber membrane bundle 15 and fixed to the fixing member 3. there is Specifically, the upper end 100B of the suppressing member 100 and the upper ends 14B of the plurality of hollow fiber membranes 14 are fixed to the fixing member 3 so that their height positions in the vertical direction match. By fixing the upper end 100B of the suppressing member 100 to the fixing member 3, the side surface of the hollow fiber membrane bundle 15 can be stably covered.

It is preferable that the length L1 in the vertical direction of the suppressing member 100 formed by the net-like body be set so as to satisfy the following formula (1). In the following formula (1), “L1” indicates the vertical length of the suppressing member 100 and “L2” indicates the effective length of the hollow fiber membrane 14 .
0.7≦L1/L2≦1.0 (1)

By setting the length L1 of the suppression member 100 in the vertical direction so as to satisfy the left side "0.7≦L1/L2" of the above formula (1), the lower end 100A of the suppression member 100 can be formed by a plurality of hollow fiber membranes. The lower end 14A of 14 can be located at a position within the above-mentioned lower end proper range that can prevent the lower end 14A from rising. On the other hand, the length L1 of the suppressing member 100 in the vertical direction is set so as to satisfy “L1/L2≦1.0” on the right side of the above equation (1), so that the lower end 100A of the suppressing member 100 is formed into a plurality of hollow portions. The lower end 14A of the thread membrane 14 can be positioned within the proper range of the lower end to prevent the mesh 101 of the suppressing member 100 from entering.

[Washing method for hollow fiber membrane module]
Next, a filtration operation by the filtration device 1 and a method for cleaning the hollow fiber membrane module 10 during the operation will be described with reference to FIG. FIG. 9 shows the relationship between each step and the opening/closing state of the valves in the basic operating method of the filtering device 1 shown in FIG. A circle in FIG. 9 means that the corresponding valve is open.

First, a water filling step (before filtration) is performed. In this step, the control device 40 opens the undiluted solution introduction valve 22 and the gas outlet valve 62 from the state in which all the valves of the filtering device 1 are closed, and the liquid feed pump 20 is operated. As a result, raw water is introduced into the water conduit 5 from the liquid feed pump 20 through the raw liquid introduction pipe 21 and supplied into the housing 13 through the pipe ventilation hole 54 . As a result, the internal space S1 of the housing 13 is filled with water.

A filtration step is then performed. In this step, after the raw water overflows from the gas vent 11, the control device 40 opens the filtrate outlet valve 71 and closes the gas outlet valve 62. FIG. The raw water filled in the internal space S1 permeates from the outer surface side of the hollow fiber membrane 14 through the wall surface to the inner surface side, and is taken out as a filtrate from the space S2 on the filtrate side.

As the filtration time elapses, suspended contaminants in the raw water adhere to the outer surface of the hollow fiber membrane 14, thereby lowering the filtration capacity. Therefore, after filtration is performed for a certain period of time, the membrane surfaces of the hollow fiber membranes 14 are cleaned by carrying out the method for cleaning the hollow fiber membrane module 10 described below.

First, a backwash process is performed. In this step, the controller 40 opens the undiluted solution outlet valve 42 and the first gas introduction valve 34 to operate the air compressor 30 . As a result, gas (for example, air) is introduced from the filtrate-side gas inlet 53 into the filtrate-side space S2 of the housing 13, and the filtrate is pressurized by the gas. The filtrate is pushed out from the inner surface side of the hollow fiber membrane 14 to the outer surface side, and as a result, part of the liquid in the internal space S1 is discharged from the drain port 12 to the outside of the system. In this manner, backwashing of the hollow fiber membranes 14 is performed. Thereafter, by opening the filtrate-side depressurization valve 81, the pressure in the filtrate-side space S2 is reduced.

Next, a water filling process (before lower bubbling) is performed. In this step, the control device 40 opens the gas outlet valve 62 and the undiluted liquid introduction valve 22 to operate the liquid feed pump 20 in order to raise the liquid level in the internal space S1 that has decreased during the backwashing process. As a result, the liquid is introduced into the internal space S1 and the liquid level rises. After that, the liquid feed pump 20 is stopped, the undiluted liquid introduction valve 22 is closed, and the liquid supply is stopped.

Next, a lower bubbling step is performed. In this step, the second gas introduction valve 35 is opened by the control device 40 and the air compressor 30 is operated while the internal space S1 is filled with water. As a result, the gas is supplied from the diffuser gas inlet 7 into the housing 13 through the second gas introduction pipe 32 . After the gas is accommodated in the gas receiving portion 45, the gas is dispersed from the air diffusion vent 43 to the lower space S12. Then, the gas rising from the lower space S12 to the upper space S11 causes the plurality of hollow fiber membranes 14 to oscillate within the respective hollow fiber membrane bundles 15 that are independent of each other by the suppressing member 100, and adhere to the membrane surface by this action. Suspended contaminants are peeled off. As described above, in the lower bubbling step, the gas is dispersed in the housing 13 at a position below the plurality of hollow fiber membrane bundles 15, and the gas is raised to the upper space S11, thereby creating the lower space S12 and the upper space S12. The hollow fiber membrane 14 located in the lower portion of the space S11 is washed.

Suspended contaminants peeled off from the membrane surfaces of the plurality of hollow fiber membranes 14 in each hollow fiber membrane bundle 15 are discharged through the gaps between the hollow fiber membrane bundles 15 . As a result, suspended contaminants adhering to the surface of the hollow fiber membranes 14 in each hollow fiber membrane bundle 15 can be effectively removed. Moreover, the suppression member 100 allows the hollow fiber membrane bundles 15 to become independent from each other, thereby suppressing interference between the hollow fiber membranes 14 belonging to different hollow fiber membrane bundles 15 . As a result, it is possible to prevent the hollow fiber membranes 14 from entangling between the hollow fiber membrane bundles 15 and to prevent the hollow fiber membranes 14 from being damaged.

In addition, since the suppressing member 100 suppresses the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 from rising, excessive movement of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 is restricted. be. Therefore, excessive interference between the hollow fiber membranes 14, such as entanglement of the hollow fiber membranes 14 belonging to the same hollow fiber membrane bundle 15, can be suppressed, and accompanying damage to the hollow fiber membranes 14 can be suppressed. can. Furthermore, by setting the position of the lower end 100A of the suppressing member 100 so that the lower end 14A of the hollow fiber membrane 14 can be suppressed from entering the mesh 101 of the suppressing member 100, the hollow fiber membrane 14 can be entangled with the suppressing member 100. can be regulated. As a result, damage to the hollow fiber membrane 14 can be suppressed.

Next, a drainage process is performed. In this step, the controller 40 closes the second gas introduction valve 35 and opens the undiluted solution outlet valve 42 . As a result, the liquid containing suspended contaminants separated from the membrane surface in the lower bubbling step is discharged out of the system through the drain port 12 .

Next, a water filling process (before upper bubbling) is performed. In this step, the gas outlet valve 62 and the undiluted solution introduction valve 22 are opened, and the liquid transfer pump 20 is operated to fill the internal space S1 with the liquid again.

Next, an upper bubbling process is performed. This step is performed for the purpose of more reliably removing suspended contaminants adhering to the membrane surface at the upper ends 14B of the hollow fiber membranes 14 that were insufficiently cleaned in the lower bubbling step.

First, the controller 40 closes the undiluted solution introduction valve 22 and opens the third gas introduction valve 36 . As a result, the gas is introduced into the water pipe 5 from the water pipe gas inlet 8 via the third gas introduction pipe 33 . The gas rises in the pipe due to buoyancy and is dispersed in the housing 13 through the pipe ventilation holes 54A and 54B located in the upper space S11. As a result, the vicinity of the upper end 14B of the hollow fiber membrane 14 can be subjected to bubbling cleaning, and suspended contaminants adhering to the membrane surface around the upper end 14B, which cannot be sufficiently removed in the lower bubbling step, are more reliably removed. be able to. Thus, in the upper bubbling step, the hollow fiber membrane 14 is washed by dispersing the gas in the housing 13 at the position of the upper space S11.

Further, in the upper bubbling step, since the entire internal space S1 is filled with water immediately after the bubbling is started, bubbling cleaning can be performed by the gas discharged from the uppermost pipe ventilation hole 54A and the lower pipe ventilation hole 54B. . Then, when a certain period of time has passed since the start of bubbling, the liquid containing the gas is discharged from the gas vent 11, and the liquid level in the internal space S1 drops to the lower surface 11A. Even in this state, the buoyancy of the gas supplied to the water conduit 5 causes the water in the water conduit 5 to be jetted out together with the gas from the pipe ventilation hole 54A above the lower surface 11A of the gas vent 11, thereby removing the water in the housing 13. It can be made to flow into the water guide pipe 5 from the pipe ventilation hole 54B below the lower surface 11A of the gas vent 11 . As a result, the mixed fluid of liquid and gas can be continuously ejected and bubbled from the pipe ventilation hole 54A above the lower surface 11A of the gas vent 11, so that the upper end 14B of the hollow fiber membrane 14 can be effectively bubbled. can be washed.

Next, a drainage process is performed. In this step, the third gas introduction valve 36 is closed and the undiluted solution outlet valve 42 is opened. As a result, the liquid containing suspended contaminants separated from the membrane surface in the upper bubbling step is discharged from the drain port 12 to the outside of the system. After the hollow fiber membrane module 10 is washed as described above, the filtration operation is restarted.

In both the upper and lower bubbling steps, the gas supply flow rate is preferably 12000 NL/h or less, preferably within the range of 1500 to 12000 NL/h. In the lower bubbling step, if the flow rate of gas supply becomes excessive, the hollow fiber membranes 14 may become entangled with each other and the membrane surface may be damaged. In contrast, in the present embodiment, in the lower bubbling step, the suppressing member 100 suppresses excessive swinging of the hollow fiber membranes 14 for each hollow fiber membrane bundle 15, so that the upper limit gas supply flow rate in the lower bubbling step is set to can be increased. In general, such a problem is less likely to occur in the upper bubbling process. Also in the bubbling process, it becomes possible to supply the gas at the same flow rate as in the upper bubbling process.

(Second embodiment)
Next, the structure of the hollow fiber membrane module 10 according to the second embodiment of the invention will be described with reference to FIG. The hollow fiber membrane module 10 according to the second embodiment basically has the same configuration as that of the first embodiment, and has the same effect. is different from that of the first embodiment.

In the hollow fiber membrane module 10 according to the second embodiment, each suppressing member 100 has a plurality of meshes 101, as in the case of the first embodiment, so as to cover the side surface of the corresponding hollow fiber membrane bundle 15. It is composed of a net-like body extending in the vertical direction. Although the upper end 100B of the suppressing member 100 is fixed to the fixing member 3 in the first embodiment, the upper end 100B of the suppressing member 100 is positioned below the upper end 14B of the hollow fiber membrane 14 in the second embodiment. ing. In other words, the upper end 100B of the suppressing member 100 is separated from the fixing member 3 . In this case, the suppression member 100 is adhesively fixed to the side surface 13B of the housing 13, for example.

As in the case of the first embodiment, the lower end 100A of the suppressing member 100 can suppress the lower ends 14A of the plurality of hollow fiber membranes 14 swinging in the corresponding hollow fiber membrane bundle 15 from whirling up. The lower ends 14A of the hollow fiber membranes 14 are located within the proper range of the lower ends that can prevent the mesh 101 from entering.

By suppressing the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 to which the suppressing member 100 corresponds, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 can be suppressed from being entangled with each other. can. Furthermore, by setting the position of the lower end 100A of the suppressing member 100 so that the lower end 14A of the hollow fiber membrane 14 can be suppressed from entering the mesh 101 of the suppressing member 100, the hollow fiber membrane 14 can be entangled with the suppressing member 100. can be regulated. As a result, damage to the hollow fiber membrane 14 can be suppressed.

(Third embodiment)
Next, the structure of the hollow fiber membrane module 10 according to the third embodiment of the invention will be described with reference to FIG. The hollow fiber membrane module 10 according to the third embodiment has basically the same configuration as that of the first embodiment, and has the same effect. is different from that of the first embodiment.

As shown in FIG. 11, each restraining member 100 of the third embodiment is formed with a plurality of through-holes 103 and is composed of a cylindrical body 102 extending vertically so as to cover the side surface of the corresponding hollow fiber membrane bundle 15. ing. The suppressing member 100 of the first embodiment is composed of a mesh body and has elasticity according to the deformation of the shape of the mesh 101. However, in the suppressing member 100 of the third embodiment, the shape of the through holes 103 It is rigid enough not to deform. As a result, each of the suppressing members 100 can make each hollow fiber membrane bundle 15 more reliably separate from each other. Therefore, in the bubbling step, interference between the hollow fiber membranes 14 belonging to different hollow fiber membrane bundles 15 is more reliably suppressed.

The upper end 100B of the suppressing member 100 of the third embodiment is fixed to the upper ends 14B of the plurality of hollow fiber membranes 14 in the corresponding hollow fiber membrane bundle 15 and fixed to the fixing member 3 . Further, the lower end 100A of the suppressing member 100 can suppress the lower ends 14A of the plurality of hollow fiber membranes 14 swinging within the corresponding hollow fiber membrane bundle 15 from rising up, as in the case of the first embodiment. In addition, the lower ends 14</b>A of the plurality of hollow fiber membranes 14 are located within the proper range of the lower ends that can prevent the penetration of the through holes 103 .

By suppressing the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 to which the suppressing member 100 corresponds, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 can be suppressed from being entangled with each other. can. Furthermore, by setting the position of the lower end 100A of the suppressing member 100 so that the lower end 14A of the hollow fiber membrane 14 can be suppressed from entering the through hole 103 of the suppressing member 100, the hollow fiber membrane 14 is entangled with the suppressing member 100. can be regulated. As a result, damage to the hollow fiber membrane 14 can be suppressed.

(Fourth embodiment)
Next, the structure of the hollow fiber membrane module 10 according to the fourth embodiment of the invention will be described with reference to FIG. The hollow fiber membrane module 10 according to the fourth embodiment basically has the same configuration as that of the first embodiment, and has the same effect. is different from that of the first embodiment.

As shown in FIG. 12 , each suppressing member 100 of the fourth embodiment is composed of a helical string-like body wound around the side surface of the corresponding hollow fiber membrane bundle 15 . The suppressing member 100, which is a spiral string-like body, is wound around the side surface of the hollow fiber membrane bundles 15 to make the hollow fiber membrane bundles 15 independent from each other. Thereby, in the bubbling step, interference between the hollow fiber membranes 14 belonging to the hollow fiber membrane bundles 15 different from each other is suppressed.

The upper end 100B of the suppressing member 100 of the fourth embodiment is fixed to the upper ends 14B of the plurality of hollow fiber membranes 14 in the corresponding hollow fiber membrane bundle 15 and fixed to the fixing member 3 . Further, the lower end 100A of the suppressing member 100 can suppress the lower ends 14A of the plurality of hollow fiber membranes 14 swinging within the corresponding hollow fiber membrane bundle 15 from rising up, as in the case of the first embodiment. In addition, the lower ends 14</b>A of the plurality of hollow fiber membranes 14 are positioned within the proper range of lower ends that can suppress catching on the suppressing member 100 .

By suppressing the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 to which the suppressing member 100 corresponds, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 can be suppressed from being entangled with each other. can. Further, by setting the position of the lower end 100A of the suppressing member 100 so as to suppress the lower end 14A of the hollow fiber membrane 14 from being caught by the suppressing member 100, the entanglement of the hollow fiber membrane 14 with the suppressing member 100 is restricted. be able to. As a result, damage to the hollow fiber membrane 14 can be suppressed.

(Fifth embodiment)
Next, the structure of the hollow fiber membrane module 10 according to the fifth embodiment of the invention will be described with reference to FIG. The hollow fiber membrane module 10 according to the fifth embodiment basically has the same configuration as that of the first embodiment, and has the same effect. is different from that of the first embodiment.

As shown in FIG. 13 , each suppressing member 100 of the fifth embodiment is composed of a plurality of band-shaped bodies 104 wound around the side surface of the corresponding hollow fiber membrane bundle 15 . The plurality of band-shaped bodies 104 are arranged at predetermined intervals in the vertical direction of the hollow fiber membrane bundle 15, and are adhesively fixed to the side surface 13B of the housing 13, for example. The suppressing member 100 composed of a plurality of band-shaped bodies 104 separates the hollow fiber membrane bundles 15 from each other with the band-shaped bodies 104 wound around the side surfaces of the hollow fiber membrane bundles 15 . Thereby, in the bubbling step, interference between the hollow fiber membranes 14 belonging to the hollow fiber membrane bundles 15 different from each other is suppressed.

The lowermost band 104 among the plurality of band-shaped members 104 has the lower end appropriate range capable of suppressing the lower ends 14A of the plurality of hollow fiber membranes 14 swinging in the corresponding hollow fiber membrane bundle 15 from rising. Located inside. By suppressing the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 to which the suppressing member 100 corresponds, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 can be suppressed from being entangled with each other. can.

[Example of the present invention]
Next, an example showing the present invention more concretely will be described.

(Example 1)
As the hollow fiber membrane bundle 15, one end free type having a membrane area of 40 m ² was used. The hollow fiber membrane 14 was made of a polyvinylidene fluoride resin hydrophilized with polyvinyl alcohol, had an average pore diameter of 0.02 microns, and had a vertical length (effective length) L2 of 1035 mm. .

As the suppressing member 100, a net-like body made of polypropylene was used. The upper end of the mesh was fixed to the upper ends 14B of the plurality of hollow fiber membranes 14 in the corresponding hollow fiber membrane bundle 15 and fixed to the fixing member 3, and the length L1 of the mesh in the vertical direction was 725 mm. In this case, the lower end of the net-like body is positioned within an appropriate lower end range that can prevent the lower ends 14A of the hollow fiber membranes 14 from rising and prevent the lower ends 14A of the hollow fiber membranes 14 from entering the mesh. . Also, the ratio (L1/L2) of the length L1 of the mesh to the effective length L2 of the hollow fiber membrane 14 is "0.7".

As the water conduit 5, a cylindrical one having a length of 1090.5 mm and an inner diameter of 48.6 mm was used. The water conduit 5 was arranged in the center of the housing 13 and fixed together with the hollow fiber membrane bundle 15 by the fixing member 3 . In this case, a plurality of hollow fiber membrane bundles 15 are arranged so as to surround the water conduit 5 . In the water conduit 5, a plurality of pipe vent holes 54 (total of 36) were formed at an interval of 100 mm from a position 70 mm away from the fixing member 3 downward. The pipe ventilation holes 54 were formed at intervals of 90° in the circumferential direction and had a hole diameter of 10 mm.

The diffuser member 4 was attached at a position 1060.5 mm below the fixed member 3 . The diffuser member 4 is composed of a disc-shaped body portion 44 in which a plurality of diffuser ventilation holes 43 are formed, a gas receiving portion 45 , and a peripheral wall portion 47 . A water guide pipe gas inlet 8 was provided as a gas supply port to the water guide pipe 5 , and an aeration gas inlet 7 was provided as a gas supply port to the gas receiving portion 45 of the air diffusion member 4 .

Using the hollow fiber membrane module 10 configured as described above, clean water was used as raw water, and constant flow rate filtration was performed for 30 seconds at a flow rate of 4000 L/h by an external pressure total filtration method. After the filtration operation, back pressure washing was performed with compressed air of 0.2 MPa from the filtrate side of the hollow fiber membrane module 10, and then bubbling washing was performed. This operation was repeated 300 times. The flow rate of bubbling air (cleaning gas) on the diffuser member 4 side was varied in the range of 1500 to 12000 NL/h. The flow rate of the bubbling air (cleaning gas) on the water conduit 5 side was kept constant at 10000 NL/h.

(Example 2)
It was the same as Example 1 except that the length L1 in the vertical direction was 932 mm. In this case, the lower end of the net-like body is positioned within the appropriate lower end range. Also, the ratio (L1/L2) of the length L1 of the mesh to the effective length L2 of the hollow fiber membrane 14 is "0.9".

(Example 3)
It was the same as Example 1 except that the length L1 in the vertical direction was 1035 mm. In this case, the lower end of the net-like body is positioned within the appropriate lower end range. Also, the ratio (L1/L2) of the length L1 of the mesh to the effective length L2 of the hollow fiber membrane 14 is "1.0".

(Comparative example 1)
The procedure was the same as in Example 1 except that the installation of the mesh-like body on the hollow fiber membrane bundle 15 was omitted.

(Comparative example 2)
It was the same as Example 1, except that a net-like body with a vertical length L1 of 518 mm was used. In this case, the lower end of the net-like body is located above the appropriate lower end range. Also, the ratio (L1/L2) of the length L1 of the mesh to the effective length L2 of the hollow fiber membrane 14 is "0.5".

(Comparative Example 3)
The same procedure as in Example 1 was carried out, except that a net-like body having a length L1 in the vertical direction of 1242 mm was used. In this case, the lower end of the net-like body is positioned below the appropriate lower end range. Also, the ratio (L1/L2) of the length L1 of the mesh to the effective length L2 of the hollow fiber membrane 14 is "1.2".

Regarding Examples 1 to 3 and Comparative Examples 1 to 3 described above, entanglement and damage between the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 were visually evaluated. Table 1 shows the evaluation results. "O" in Table 1 indicates that the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 were hardly entangled or damaged, and stable operation was possible. On the other hand, "x" in Table 1 indicates that the occurrence of entanglement or damage between the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 was remarkably confirmed, making it difficult to continue stable operation. show.

As is clear from the results in Table 1, in Examples 1 to 3, when the flow rate of the cleaning gas on the diffuser member 4 side was in the range of 1500 to 12000 NL/h, the hollow fiber membranes in the hollow fiber membrane bundle 15 The occurrence of entanglement and damage between the members 14 is suppressed. This is because the mesh-like body restrains the lower ends 14A of the plurality of hollow fiber membranes 14 from rising in the hollow fiber membrane bundle 15, thereby restricting excessive movement of the hollow fiber membranes 14. FIG.

Further, in Examples 1 to 3, the lower end of the mesh body can suppress the lower end 14A of the hollow fiber membrane 14 from rising and the lower end appropriate range capable of suppressing the lower end 14A of the hollow fiber membrane 14 from entering the mesh. Located inside. It is believed that this restricts the entanglement of the hollow fiber membranes 14 with the mesh structure, and suppresses the occurrence of damage to the hollow fiber membranes 14 .

On the other hand, in Comparative Example 1, under the condition that the flow rate of the cleaning gas on the diffuser member 4 side is 7000 NL/h or more, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 are significantly entangled or damaged. was confirmed by This is because, in Comparative Example 1, since the installation of the mesh-like body is omitted, the excessive movement of the plurality of hollow fiber membranes 14 within the hollow fiber membrane bundle 15 is not restricted, and the lower ends 14A of the plurality of hollow fiber membranes 14 are not restricted. This is because a surge occurred in

Further, in Comparative Example 2, under the condition that the flow rate of the cleaning gas on the diffuser member 4 side is 10000 NL/h or more, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 are significantly entangled or damaged. was confirmed by This is because, in Comparative Example 2, the lower end of the net-like body is located above the appropriate lower end range in which the lower ends 14A of the plurality of hollow fiber membranes 14 can be suppressed from rising within the hollow fiber membrane bundle 15. be. Therefore, in Comparative Example 2, under the condition that the flow rate of the cleaning gas on the diffuser member 4 side is 10000 NL/h or more, the lower ends 14A of the plurality of hollow fiber membranes 14 in the hollow fiber membrane bundle 15 are swirled up. It is thought that the hollow fiber membranes 14 were entangled or damaged along with this.

Further, in Comparative Example 3, when the flow rate of the cleaning gas on the diffuser member 4 side was in the range of 1500 to 12000 NL/h, the hollow fiber membranes 14 in the hollow fiber membrane bundle 15 were significantly entangled or damaged. was confirmed by This is because, in Comparative Example 3, the lower end of the mesh-like body is positioned below the appropriate lower end range in which entry of the lower ends 14A of the hollow fiber membranes 14 into the mesh 101 can be suppressed, and is in contact with the diffuser member 4. It is because Therefore, in Comparative Example 3, the hollow fiber membrane 14 was entangled with the suppressing member 100, and the hollow fiber membrane 14 was damaged.

From the above results, in Examples 1 to 3, compared to Comparative Examples 1 to 3, excessive movement of the hollow fiber membranes 14 in the bubbling process was restricted, and suspended contaminants adhering to the membrane surface of the hollow fiber membranes 14 It has been found that entanglement and damage between the hollow fiber membranes 14 can be suppressed while ensuring the removal effect of .

It should be understood that the embodiments and examples disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

2 gas supply part 4 air diffusion member 43 air diffusion hole 44 body part 45 gas receiving part 45A socket 46 dispersion hole 10 hollow fiber membrane module 13 housing 14 hollow fiber membrane 15 hollow fiber membrane bundle 100 suppressing member S1 internal space

Claims (7)

a housing in which the fixing member is fixed and which defines an internal space;
a plurality of hollow fiber membrane bundles each having a plurality of hollow fiber membranes and arranged in the internal space with the upper ends of the plurality of hollow fiber membranes fixed to the fixing member;
a gas supply unit that supplies a gas for cleaning the plurality of hollow fiber membrane bundles into the internal space;
a suppressing member provided individually for each of the plurality of hollow fiber membrane bundles,
Each of the suppressing members allows the plurality of hollow fiber membranes in the corresponding hollow fiber membrane bundle to oscillate by the gas supplied from the gas supply unit into the internal space, while allowing the plurality of hollow fiber membranes to oscillate. A hollow fiber membrane module configured to prevent the lower end of the hollow fiber membrane from rising. Each of the suppressing members has a plurality of meshes and is composed of a mesh-like body extending vertically so as to cover the side surface of the corresponding hollow fiber membrane bundle,
The lower ends of the suppressing members are capable of suppressing the lower ends of the plurality of hollow fiber membranes swinging in the corresponding hollow fiber membrane bundle from rising, and the lower ends of the plurality of hollow fiber membranes entering the mesh. 2. The hollow fiber membrane module according to claim 1, which is located at a position capable of suppressing this. The upper ends of the suppressing members are respectively fixed to the fixing member,
3. The hollow fiber membrane module according to claim 2, wherein the vertical length of each of the suppressing members is set to satisfy the following formula (1).
0.7≦L1/L2≦1.0 (1)
[In formula (1), "L1" indicates the vertical length of the suppressing member, and "L2" indicates the effective length of the hollow fiber membrane. ] The hollow structure according to any one of claims 1 to 3, wherein each of the suppressing members has a function of partitioning the hollow fiber membrane bundles so that a gap is formed between the plurality of hollow fiber membrane bundles. thread membrane module. The gas supply unit is arranged at a position below the hollow fiber membrane bundle, has a shape that expands in the radial direction of the hollow fiber membrane bundle, and has a plurality of air diffusion passages that are spaced apart in the radial direction. including an air diffusion member having pores formed therein;
The diffuser member
a plate-shaped main body having a shape that spreads in the radial direction of the hollow fiber membrane bundle, and in which a plurality of the air diffusion holes are formed at intervals in the radial direction;
It has a cylindrical shape with one end connected to the lower surface of the main body and a gas receiving port formed on the other end side, and the dispersion for guiding the gas accommodated in the cylinder to the air diffusion vent. 5. The hollow fiber membrane module according to any one of claims 1 to 4, comprising a gas receiving portion in which holes are formed. 6. The hollow fiber membrane module according to claim 5, wherein the gas receiving portion has a shape whose inner diameter increases from the one end toward the other end. The air diffusion holes are arranged on a plurality of circles spaced apart in the radial direction in the main body,
7. The hollow fiber membrane module according to claim 5, wherein the number of air diffusion holes on each circumference is a multiple of the number of hollow fiber membrane bundles.

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