External pressure type hollow fiber membrane module and its manufacturing method

Abstract

To provide an external pressure type hollow fiber membrane module excellent in durability and superior in uniformity of pressure and speed distributions of a fluid passing through inside.SOLUTION: An external pressure type hollow fiber membrane module comprises: a hollow fiber membrane bundle 3 prepared by bundling a plurality of hollow fiber membranes 2 in which one end part is closed and the other end part is opened; a housing 4 having a nozzle on a side face and accommodating the hollow fiber membrane bundle so that an end part heads for a longitudinal direction; first and second commutation cylinders 11a and 11b mounted between both end parts of the hollow fiber membrane bundle 3 and the housing; a first adhesion stationary portion 5a of the opening end side of the hollow fiber membrane; a second adhesion stationary portion 5b having at least one through-hole 6 parallel to the longitudinal direction of the housing in the circumference of the hollow fiber membrane bundle 3 at a closed end side; and a protective member 7 covering the outer peripheral surface of the hollow fiber membrane bundle. The through-hole 6 is disposed so as to adjoin the outer peripheral surface of the hollow fiber membrane bundle, and the cross-sectional shape of the through-hole 6 in a direction orthogonal to the longitudinal direction of the housing is like a partial circular arc having a width. The protective member 7 is provided so as to contact the hollow fiber membrane bundle 3 and the through-hole 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an external pressure type hollow fiber membrane module and a method for producing the same. [Background technology]

[0002] In lines that produce ultrapure water used in the manufacture of electronic and electrical components such as semiconductors and display elements, ultrapure water produced using microfiltration membranes, ion exchange resins, reverse osmosis filtration membranes, etc. is finally filtered using microfiltration membranes or ultrafiltration membranes just before being supplied to the point of use. For this final filtration, an external pressure type hollow fiber membrane module is mainly used, in which a hollow fiber membrane bundle made of multiple hollow fiber membranes bundled together is housed in a housing, and the water to be treated is supplied to the outside of the hollow fiber membranes and filtered inside the hollow fiber membranes (hollow parts).

[0003] For example, the external pressure type hollow fiber membrane module described in Patent Document 1 is erected so that its longitudinal direction is vertical, and an upper nozzle for discharging filtrate and a lower nozzle for supplying water to be treated are arranged at the vertically upper and lower sides, respectively, so as to protrude in a direction perpendicular to the longitudinal direction of the housing. Both ends of the hollow part of the hollow fiber membrane are open, and both ends of the hollow fiber membrane bundle are adhesively fixed to the housing by an adhesive fixing layer. The water to be treated supplied from the lower nozzle is filtered from the outside to the inside (hollow part) of the hollow fiber membrane within the housing, and filtrate is discharged from both the top and bottom ends of the housing, and waste water is discharged from the upper nozzle.

[0004] Moreover, the external pressure type hollow fiber membrane module described in Patent Document 2 is erected so that its longitudinal direction is vertical, and a nozzle for discharging wastewater is disposed vertically upward so as to protrude in a direction perpendicular to the longitudinal direction of the housing. The hollow fiber membrane is disposed in the housing so that one end of the hollow part is sealed and the other end of the hollow part is open, with the sealed end being vertically downward and the open end being vertically upward. Moreover, only the open end side of the hollow fiber membrane bundle is adhesively fixed to the housing. The water to be treated supplied from the lower end of the housing is supplied to the outside of the hollow fiber membrane through a gap between the inner wall of the housing and a sealing part that seals one end of the hollow fiber membrane, and is filtered into the inside (hollow part) of the hollow fiber membrane, and the filtrate is discharged from the upper end of the housing and the wastewater is discharged from the nozzle.

[0005] In the external pressure type hollow fiber membrane module described in Patent Document 3, similarly to Patent Document 2, when the water to be treated is supplied from the lower end of the housing, it is filtered from the outside to the inside (hollow portion) of the hollow fiber membrane, and the filtrate is discharged from the upper end of the housing and the waste water is discharged from the nozzle, but both ends (sealed end and open end) of the hollow fiber membrane bundle are adhesively fixed to the housing by adhesive fixing parts. Also, the water to be treated supplied from the lower end of the housing is supplied to the outside of the hollow fiber membrane through the through holes provided in the adhesive fixing part. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-45453 A [Patent Document 2] JP 2015-182056 A [Patent Document 3] JP 2017-100105 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the external pressure type hollow fiber membrane module described in Patent Document 1, the water to be treated is supplied from the lower nozzle in a direction perpendicular to the hollow fiber membrane, and the wastewater is discharged from the upper nozzle in a direction perpendicular to the hollow fiber membrane. This results in a problem in that vertical water pressure is applied to the hollow fiber membrane, causing stress to concentrate on the fixing portions at both ends of the hollow fiber membrane bundle, making the ends (bases) of the hollow fiber membranes prone to breakage.

[0008] In the external pressure type hollow fiber membrane module described in Patent Document 2, the water to be treated is supplied parallel to the hollow fiber membranes, so the above-mentioned concentration of stress caused by the supply of the water to be treated is alleviated. However, the concentration of stress caused by the discharge of the effluent water still remains, so the maximum amount of deflection near the discharge nozzle of the effluent water increases, and there is still a problem that the end (base) of the hollow fiber membrane is likely to break. In addition, since the sealed end side of the hollow fiber membrane is not adhesively fixed to the housing, the hollow fiber membrane bundle is pushed up by the inflow of the water to be treated, which may cause the hollow fiber membrane to buckle.

[0009] In the external pressure type hollow fiber membrane module described in Patent Document 3, the water to be treated is supplied parallel to the hollow fiber membranes, and both ends of the hollow fiber membrane bundle are adhesively fixed to the housing, so that the concentration of stress caused by the supply of the water to be treated as described above is alleviated and the maximum amount of deflection is also small. However, in order to increase both the number of hollow fiber membranes per unit volume and the amount of water to be treated supplied to the hollow fiber membrane bundle, reduce pressure loss, and perform efficient filtration, there is room for improvement in the shape and opening area of ​​the through holes. In addition, the external pressure type hollow fiber membrane module described in Patent Document 3 is suitable for use in a filtration device or the like that removes endotoxins from raw water clarified in a pure water production system. Therefore, in order to use it for the final filtration of ultrapure water, further improvements are required for the hollow fiber membranes used.

[0010] Therefore, an object of the present invention is to provide an external pressure type hollow fiber membrane module which is highly durable and has excellent uniformity in the pressure distribution and velocity distribution of the fluid passing through it. [Means for solving the problem]

[0011] As a result of extensive research into solving the above-mentioned problems, the inventors discovered that the above-mentioned problems could be solved by making the opening shape of the through holes through which the treated water is supplied to the hollow fiber membrane bundle a predetermined shape, and thus completed the present invention.

[0012] That is, the present invention is as follows. [1] A hollow fiber membrane bundle including a plurality of hollow fiber membranes, each of which has one end closed and the other end open; a housing that is a cylindrical body having at least one nozzle on a side surface and that accommodates the hollow fiber membrane bundle such that the closed end of the hollow fiber membrane and the open end of the hollow fiber membrane face both ends of the cylindrical body in the longitudinal direction; a first straightening tube mounted between the open end of the hollow fiber membrane bundle and the end of the housing; a second straightening tube installed between the closed end of the hollow fiber membrane bundle and the end of the housing; a first adhesive fixing portion that adhesively fixes the hollow fiber membranes to each other and the hollow fiber membrane bundle to the inner wall of the housing at the open end side of the hollow fiber membranes; a second adhesive fixing portion that adhesively fixes the hollow fiber membranes to each other and the hollow fiber membrane bundle to the inner wall of the housing at the closed end side of the hollow fiber membranes, and has at least one through hole parallel to the longitudinal direction of the housing on the outer periphery of the hollow fiber membrane bundle; a protective member that covers the entire outer circumferential surface of the hollow fiber membrane bundle in a state of being in close contact with the outer circumferential surface of the hollow fiber membrane bundle in at least one of an end region of at least a predetermined length from the first adhesive fixing part toward the second adhesive fixing part and an end region of at least a predetermined length from the second adhesive fixing part toward the first adhesive fixing part; a cap having an opening and attached to both ends of the housing in the longitudinal direction; the through hole is disposed adjacent to an outer peripheral surface of the hollow fiber membrane bundle, and a cross-sectional shape of the through hole in a direction perpendicular to the longitudinal direction of the housing is a partial arc shape having a width, a ratio (A / S) of a sum A of opening areas of the through holes to an area S obtained by subtracting an area defined by an outer peripheral surface of the protective member from an area defined by an inner wall of the housing in a cross section perpendicular to the longitudinal direction of the housing is 0.4 to 0.6; The total opening area of ​​the through holes is A, the total opening area of ​​the hollow parts of the hollow fiber membrane is B, and the opening area of ​​the opening of the cap is C, and the relationship between A, B, and C is within 0.9. The protective member is provided between the hollow fiber membrane bundle and the through hole so as to be in contact with the hollow fiber membrane bundle and the through hole. An external pressure type hollow fiber membrane module. [2 ] ] The protective member is disposed across the first adhesive fixing portion and the second adhesive fixing portion, or [2] The external pressure type hollow fiber membrane module described above. [ 3 ] The protective member is a net-like member formed into a cylindrical shape. [1] [Figure 1] 2. An external pressure type hollow fiber membrane module according to claim 1 . [ 4 ] The net-like member has a wire diameter of 0.2 to 1.5 mm and an opening ratio of 40 to 90%. 3 ] An external pressure type hollow fiber membrane module according to the present invention. [ 5 ] At least one of the openings of the caps has a structure in which the opening is sealed and fixed with a packing having the same inner diameter as the opening, [1] to [ 4 13. An external pressure type hollow fiber membrane module according to any one of claims 1 to 12. [ 6 ] [1]~[ 5

[0023] A method for producing an external pressure type hollow fiber membrane module according to any one of the following: a first straightening tube and a second straightening tube are attached to the housing; a hollow fiber membrane bundle covered with the protective member is inserted into the housing; a casting jig having at least one convex portion on a substantially disc-shaped surface, the cross-sectional shape of which is a partial arc having a width in a cross section parallel to the substantially disc-shaped surface, is attached between the protective member and the housing so that the convex portion is positioned; a gap between the protective member and the housing is filled with a potting material, which is solidified, and then the casting jig is removed, thereby bringing the outer peripheral surface of the hollow fiber membrane bundle and the protective member into a tightly adhered state; and at least one through hole, the cross-sectional shape of which is a partial arc having a width in a cross-sectional direction perpendicular to the longitudinal direction of the housing, is opened on the outside of the protective member. Effect of the Invention

[0013] According to the present invention, it is possible to provide an external pressure type hollow fiber membrane module which is highly durable and has excellent uniformity in the pressure distribution and velocity distribution of a fluid passing through the inside. [Brief description of the drawings]

[0014] [Diagram 2] FIG. 1 is a vertical end view showing a schematic structure of one embodiment of an external pressure type hollow fiber membrane module according to the present invention. [Diagram 3] 2 is a cross-sectional view of the external pressure type hollow fiber membrane module shown in FIG. 1 taken along the line AA. [Figure 4] FIG. 1(a) is a perspective view showing an example of a casting jig used for making through-holes when producing the external pressure-type hollow fiber membrane module shown in Fig. 1. FIG. 1(b) is a perspective view showing a cup for centrifugal casting attached to an end of a first cylindrical member for making a first adhesive fixing part when producing the external pressure-type hollow fiber membrane module shown in Fig. 1. [Diagram 5] 1 is a schematic diagram showing evaluation devices used in filtration evaluation in Examples and Comparative Examples, where (a) shows the evaluation device used in Examples 1 and 2 and Comparative Example 2-1, and (b) shows the evaluation device used in Comparative Example 1. [Figure 6]1 is a schematic diagram showing a simulation model used in Example 3. (a) shows the whole model, and (b) shows the structure near the inlet. [Figure 7] 13 is a diagram showing the results of a simulation of flow analysis in Example 3. (a) shows the water pressure distribution, and (b) shows the water velocity distribution. [Figure 8] 13 is a diagram showing the results of a simulation of flow analysis in Example 4. (a) shows the water pressure distribution, and (b) shows the water velocity distribution. [Figure 9] 1 is a schematic diagram showing a simulation model used in Comparative Example 2-2, where (a) shows the whole model and (b) shows the structure near the inlet. [Figure 10] 1A and 1B are diagrams showing water velocity distribution as a simulation result of flow analysis of Comparative Example 2-2, where (a) is a distribution diagram seen from the longitudinal direction of the simulation model, and (b) is a distribution diagram seen from the direction perpendicular to the longitudinal direction of the simulation model. [Figure 11] 1 is a schematic diagram showing a simulation model used in Comparative Example 3. (a) shows the whole model, and (b) shows the structure near the inlet. [Figure 12] 13 is a diagram showing the simulation results of the flow analysis of Comparative Example 3, where (a) shows the water pressure distribution and (b) shows the water velocity distribution. [Figure 13] 1 is a schematic diagram showing a simulation model used in Comparative Example 4, where (a) shows the whole model and (b) shows the structure near the inlet. ​ 13 is a diagram showing the simulation results of flow analysis of Comparative Example 4, where (a) shows the water pressure distribution and (b) shows the water velocity distribution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Below, we will explain in detail the form for implementing the present invention (hereinafter referred to as the "present embodiment"). However, the present invention is not limited to the following description and can be implemented in various modifications within the scope of its gist.

[0016] [External pressure type hollow fiber membrane module] The external pressure type hollow fiber membrane module of this embodiment is particularly suitable for use as a final filtration membrane module for ultrapure water used for cleaning during the manufacture of silicon wafers, LSIs, liquid crystals, and the like. The configuration of one example of an external pressure type hollow fiber membrane module (hereinafter, simply referred to as a "hollow fiber membrane module") according to this embodiment will be described with reference to the drawings.

[0017] Fig. 1 is a vertical end view showing a schematic structure of an example of an external pressure type hollow fiber membrane module according to the present embodiment. In Fig. 1, the up-down direction is indicated by an arrow. In the following description, the up-down direction shown in Fig. 1 is the up-down direction of the hollow fiber membrane module 1.

[0018] As shown in FIG. 1, the hollow fiber membrane module 1 of this embodiment includes a hollow fiber membrane bundle 3 in which a plurality of hollow fiber membranes 2 are bundled together, a cylindrical housing 4 that accommodates the hollow fiber membrane bundle 3, and caps 8a and 8b.

[0019] A reverse osmosis membrane, a nanofiltration membrane, an ultrafiltration membrane, or a microfiltration membrane can be used as the hollow fiber membrane 2. The material of the hollow fiber membrane is not particularly limited, and examples thereof include polysulfone, polyethersulfone, polyacrylonitrile, polyimide, polyetherimide, polyamide, polyetherketone, polyetheretherketone, polyethylene, polypropylene, poly(4-methylpentene), ethylene-vinyl alcohol copolymer, cellulose, cellulose acetate, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, and polytetrafluoroethylene, and composite materials thereof can also be used.

[0020] The hollow fiber membrane preferably has an inner diameter of 100 to 3,000 μm and an outer diameter of 200 to 4,000 μm, more preferably an inner diameter of 200 to 2,000 μm and an outer diameter of 300 to 3,000 μm, and even more preferably an inner diameter of 400 to 1,000 μm and an outer diameter of 500 to 2,000 μm. When the inner and outer diameters are within the above ranges, the membrane has both a good permeation flux and durability, and can be suitably used for the final filtration of ultrapure water.

[0021] The molecular weight cutoff of the hollow fiber membrane is preferably 6000 or more, more preferably more than 6000. When the molecular weight cutoff of the hollow fiber membrane is within the above range, it can be suitably used as a final filtration membrane module for ultrapure water used for cleaning during the manufacture of silicon wafers, LSIs, liquid crystals, etc. In general, ultrapure water is desired to have a small number of mixed fine particles, and even if mixed, it is desired to suppress only small fine particles. However, as the purpose of ultrapure water used for cleaning during the manufacture of silicon wafers, LSIs, liquid crystals, etc., is to wash away surface impurities of silicon wafers, etc., the viewpoint of securing a large amount of water is prioritized, and a highly water-permeable hollow fiber membrane having a molecular weight cutoff in the above range is preferably used. In addition, in filtration for the purpose of removing endotoxins, the purpose is to obtain filtrate equivalent to distilled water used for the washing of injection solutions (dilution water) and pharmaceutical containers, etc., so that the water quality aspect of reducing the amount of endotoxins to below the detection limit (negative) is prioritized over the amount of permeation, and a hollow fiber membrane with a molecular weight cutoff smaller than the above range is often used. On the other hand, in filtering ultrapure water for washing in the production of silicon wafers, LSIs, liquid crystals, and the like, the size of the objects to be removed is relatively larger than endotoxins, and from the viewpoint of securing a large amount of water as described above, a highly water-permeable hollow fiber membrane having a molecular weight cutoff in the above range is preferably used. The number of hollow fiber membranes depends on the dimensions of the hollow fiber membranes and the internal cross-sectional area of ​​the housing that contains the hollow fiber membranes, but from the viewpoint of collecting a larger amount of filtered water, it is preferably 5,000 to 20,000, more preferably 7,000 to 15,000, and even more preferably 9,000 to 13,000.

[0022] Caps 8a, 8b having a funnel-shaped cross section for connecting piping are provided at both end openings of housing 4, and have openings (pipes) for connecting piping. Caps 8a, 8b are fixedly attached to housing 4 by nuts 13. An annular groove is formed in the end faces of the caps 8a, 8b on the housing 4 side and the end faces of the housing 4 on the caps 8a, 8b side, and an O-ring 14 is sandwiched by this groove. The O-ring 14 provides a liquid-tight seal between both ends of the housing 4 and the caps 8a, 8b. Specifically, the seal structure using the O-ring 14 may be the structure described in JP 2017-39122 A, for example. In addition, the openings of the caps 8a, 8b and the piping connected thereto are preferably sealed and fixed with packing having the same inner diameter as the openings of the caps 8a, 8b. When the inner diameter of the openings of the caps 8a, 8b and the inner diameter of the packing are the same, the retention of liquid in the corresponding parts of the fluid flowing inside and the generation of dust due to turbulence of the fluid are suppressed.

[0023] The housing 4 is configured by joining together a first cylindrical member 9a integrally molded with the nozzle 12a, a second cylindrical member 9b integrally molded with the nozzle 12b, and a straight third cylindrical member 10 disposed between the first cylindrical member 9a and the second cylindrical member 9b. The nozzles 12a and 12b are provided on the sides of the ends of the housing 4, respectively, and protrude in a direction perpendicular to the longitudinal direction of the housing 4. The nozzle 12a is a nozzle from which the effluent water is discharged during the external pressure filtration process. The nozzle 12b is not particularly used in the hollow fiber membrane module 1 of this embodiment, and therefore its opening is sealed.

[0024] The hollow fiber membrane module 1 of this embodiment is erected so that its longitudinal direction is vertical, with the nozzle 12a disposed on the vertical upper side and the nozzle 12b disposed on the vertical lower side.

[0025] As shown in FIG. 1, a first flow straightening cylinder 11a and a second flow straightening cylinder 11b are attached between both ends of the hollow fiber membrane bundle 3 and the first cylindrical member 9a and the second cylindrical member 9b, respectively. The first straightening tube 11a and the second straightening tube 11b are formed in a cylindrical shape, and the first straightening tube 11a is provided between the opening on the inner surface side of the housing 4 of the upper nozzle 12a and the hollow fiber membrane bundle 3, and the second straightening tube 11b is provided between the opening on the inner surface side of the housing 4 of the lower nozzle 12b and the hollow fiber membrane bundle 3, and each is provided so as to surround the outer periphery of the hollow fiber membrane bundle 3. The first straightening cylinder 11a and the second straightening cylinder 11b are provided to maintain the distance between the hollow fiber membrane bundle 3 and the inner wall of the housing 4 in the vicinity of the nozzle 12a and the nozzle 12b. The upper end of the first straightening tube 11a may be adhesively fixed within the first adhesive fixing portion 5a described later, and the lower end of the second straightening tube 11b may be adhesively fixed within the second adhesive fixing portion 5b described later. By attaching the first straightening cylinder 11a and the second straightening cylinder 11b to both ends of the housing 4, when manufacturing the hollow fiber membrane module 1, the hollow fiber membrane bundle 3 wrapped in the protective member 7 is adhered and fixed inside the housing 4 by centrifugal bonding as described below, and the hollow fiber membrane bundle 3 can be prevented from falling off downward during centrifugation.

[0026] At both ends of the hollow fiber membrane bundle 3, a first adhesive fixing portion 5a and a second adhesive fixing portion 5b are formed for adhesively fixing each hollow fiber membrane 2 to each other and between the hollow fiber membrane bundle 3 and the inner wall of the housing 4 using a potting material. By adhesively fixing both ends of the hollow fiber membrane bundle 3 in this manner, the maximum deflection of the hollow fiber membrane bundle 3 is smaller and stress concentration is alleviated compared to when only one end is adhesively fixed, thereby preventing breakage of the hollow fiber membranes 2 and resulting in a highly durable hollow fiber membrane module.

[0027] The potting material is preferably a polymeric material such as an epoxy resin, a vinyl ester resin, a urethane resin, an unsaturated polyester resin, an olefin polymer, a silicone resin, a fluorine-containing resin, etc. These polymeric materials may be used alone or in combination of two or more kinds. In addition, the first adhesive fixing part 5a and the second adhesive fixing part 5b made of these potting materials must have pressure resistance capable of withstanding the pressure difference between the primary side and the secondary side caused by pressurization during filtration, and therefore it is desirable for them to have a suitable hardness. On the other hand, in order to reliably prevent the hollow fiber membrane 2 from being broken due to the flow of fluid during physical cleaning for a long period of time, it is desirable to use a potting material with a suitable softness. Therefore, in order to provide a necessary and sufficient pressure resistance for use and to reliably prevent membrane breakage, it is preferable to use a potting material with a hardness of 80D to 50A in the operating temperature range. The hardness referred to here is the value indicated 10 seconds after pressing a type D or type A durometer against a sample surface having a substantially smooth surface in accordance with JIS K6253. If this value exceeds 80D, the above-mentioned film may break, and if it is less than 50A, pressure resistance may be insufficient.

[0028] An area into which the treated liquid flows (hereinafter referred to as the "outer area") is formed on the outside of the hollow fiber membrane bundle 3 between the first adhesive fixing portion 5a and the second adhesive fixing portion 5b formed at both ends of the hollow fiber membrane bundle 3.

[0029] Furthermore, as shown in Fig. 1, at least one through-hole 6 is formed in the second adhesive fixing part 5b located on the lower side when the hollow fiber membrane module 1 is set upright in the vertical direction. Here, Fig. 2 is a cross-sectional view of the hollow fiber membrane module 1 shown in Fig. 1 cut along the line AA.

[0030] The through-hole 6 is formed parallel to the longitudinal direction of the housing 4, and is a hole that communicates the above-mentioned outer region with the inside of the cap 8b. In this embodiment, the through-hole 6 is provided in a second adhesive fixing part 5b between a protective member 7 (to be described later) and the inner wall of the housing 4, and is disposed adjacent to the outer circumferential surface of the hollow fiber membrane bundle 3, as shown in FIG. Through hole 6 has a cross-sectional shape (opening shape) in a direction perpendicular to the longitudinal direction of housing 4 that is a partial arc shape having a certain width. In this disclosure, a partial arc shape having width does not only refer to a partial arc of a concentric circle centered on the center of the hollow portion of the housing 4 (the area defined by the inner wall of the housing) as shown in Fig. 2, but may be any shape extending along the circumferential direction of the housing, and may be, for example, one in which the contour line constituting the shape is wavy or jagged. In addition, the shape of the end of the partial arc is not particularly limited, and may be, for example, rounded as shown in Fig. 2. When the opening shape of the through hole 6 is a partial arc shape having a width, it is possible to accommodate a large number of hollow fiber membranes 2 per unit volume while having a large opening area of ​​the through hole 6, compared to when the opening shape is circular, elliptical, polygonal, etc., and the number of hollow fiber membranes 2 per unit volume and the amount of water to be treated supplied to the hollow fiber membrane bundle 3 become large and in a balanced manner, allowing for efficient filtration.

[0031] Regarding the opening shape of the through hole 6, the central angle of the partial arc centered on the center of the hollow portion of the housing 4 is preferably 45 to 85°, more preferably 60 to 80°, and even more preferably 70 to 80°, when, for example, four through holes 6 are provided. Furthermore, the width of the partial arc (the radial width of the hollow part of the housing) is preferably 0.05r to 0.25r, more preferably 0.07r to 0.20r, and further preferably 0.09r to 0.12r, where r is the radius of the hollow part of the housing.

[0032] The number of through holes 6 is not particularly limited, but from the viewpoint of making the total opening area A described later as large as possible, it is preferable that there be more than one, more preferably 2 to 8, and even more preferably 3 to 6. When a plurality of through holes 6 are present, it is preferable that the areas of the openings (partial arc-shaped cross sections having a width) are approximately the same (within a range of ±5%). Furthermore, when there are multiple through holes 6, the through holes 6 are preferably provided at equal intervals on the circumference of a circle formed by the opening (a partial arc having a width). Furthermore, when there are an even number of through holes 6, it is preferable that each of the through holes 6 is point-symmetric with respect to the center of the hollow portion of the housing 4.

[0033] In a cross section perpendicular to the longitudinal direction of the housing 4, the ratio (A / S) of the sum A of the opening areas of the through holes 6 to the area S obtained by subtracting the area of ​​the area defined by the outer peripheral surface of the protective member 7 described below (hereinafter also referred to as the "occupied area of ​​the protective member 7") from the area of ​​the area (hollow portion) defined by the inner wall of the housing 4 (hereinafter also referred to as the "internal cross-sectional area of ​​the housing 4") is preferably 0.2 to 0.7, more preferably 0.3 to 0.6, and even more preferably 0.4 to 0.5. When A / S is in the above range, the amount of water to be treated supplied to the hollow fiber membrane bundle 3 through the through holes 6 increases, allowing efficient filtration.

[0034] Further, the hollow portion of each hollow fiber membrane 2 on the side where the through-hole 6 is formed is closed by the second adhesive fixing portion 5b, and the hollow portion of each hollow fiber membrane 2 on the opposite side to the side where the through-hole 6 is formed is opened. When filtration is performed, the water to be treated flows in from the opening of the cap 8b, passes through the through-hole 6 and is supplied to the outer region. The water to be treated supplied to the outer region then seeps into the outer surface of each hollow fiber membrane 2, and the filtrate that has passed through the hollow portion of each hollow fiber membrane 2 is discharged from the opening of the cap 8a, and the discharged water is discharged from the nozzle 12a.

[0035] The hollow fiber membrane module 1 also includes a protective member 7 provided so as to cover the entire outer periphery of the hollow fiber membrane bundle 3 while being in close contact with the outer periphery of the hollow fiber membrane bundle 3. The protective member 7 may be provided in at least one of an end region of at least a predetermined length from the first adhesive fixing part 5a toward the second adhesive fixing part 5b and an end region of at least a predetermined length from the second adhesive fixing part 5b toward the first adhesive fixing part 5a, and may be disposed so as to cover the entire length of the hollow fiber membrane bundle 3 from the first adhesive fixing part 5a to the second adhesive fixing part 5b as shown in FIG. The protective member 7 preferably has flexibility, and examples of the material include polyolefins such as PE (polyethylene) and PP (polypropylene), fluororesins such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer (4.6 fluorinated)), ETFE (tetrafluoroethylene-ethylene copolymer), super engineering plastics such as polysulfone, polyethersulfone, and polyphenylene sulfone.

[0036] Further, it is particularly preferable that the protective member 7 is formed by shaping a net-like member into a cylindrical shape. When a sheet-like member instead of a net-like member is used as the protective member 7 and formed into a cylindrical shape, it is desirable to provide it not on substantially the entire outer peripheral surface of the hollow fiber membrane bundle 3 but only at both end portions of the hollow fiber membrane bundle 3 or only at one end portion of the hollow fiber membrane bundle 3 so as not to cause a decrease in filtration efficiency.

[0037] When the protective member 7 is a net-like member, the wire diameter of the net is preferably 0.2 to 1.5 mm, more preferably 0.4 to 1.2 mm, and even more preferably 0.5 to 1.0 mm. When the wire diameter is within the above range, it can follow deformations such as swelling and bending of the hollow fiber membrane bundle 3 due to water flow, and the net itself is less likely to be damaged. The opening shape of the net-like protective member 7 is not particularly limited, and examples include triangles, quadrilaterals (such as rhombuses, squares, rectangles, parallelograms, etc.), hexagons, and the like. The cross-section of the net wire constituting the net is not particularly limited and may be any of polygons such as circles, triangles, and quadrilaterals, ellipses, and the like. Further, the aperture ratio of the net-like protective member 7 is preferably 40 to 90%, more preferably 50 to 80%, and even more preferably 60 to 70% in order to efficiently supply a large amount of water to be treated to the hollow fiber membrane bundle 3. Note that the aperture ratio refers to the ratio obtained from the area of the portion where the net wire does not exist in a plan view projection. Both ends of the protective member 7 are located within the first adhesive fixing portion 5a and the second adhesive fixing portion 5b, respectively, and are fixed by the first adhesive fixing portion 5a and the second adhesive fixing portion 5b.

[0038] The protective member 7 is provided in a state of being in close contact with the outer peripheral surface of the hollow fiber membrane bundle 3 at least at one end of the hollow fiber membrane bundle 3. Specifically, the end is a first end region R1 including a boundary between the second adhesive fixing part 5b and the outer region and a region extending from the boundary toward the outer region by a predetermined length L1, and a second end region R2 including a boundary between the first adhesive fixing part 5a and the outer region and a region extending from the boundary toward the outer region by a predetermined length L2. The length L1 from the boundary in the first end region R1 is preferably 5 cm or more. In the hollow fiber membrane module 1 of this embodiment, the discharge water is discharged from the nozzle 12a as described above. When the discharge water is discharged from the nozzle 12a, a suction force acts on the hollow fiber membrane 2 near the nozzle 12a, increasing the tendency for the hollow fiber membrane 2 to break, and the hollow fiber membrane 2 may easily break. Therefore, the length L2 from the boundary in the second end region R2 is preferably set to a length such that the lower end of the second end region R2 is located lower than the lower end of the opening of the nozzle 12a on the inner surface side of the housing 4. This makes it possible to suppress deformation of the hollow fiber membrane 2 near the nozzle 12a caused by the suction force generated when the discharge water is discharged from the nozzle 12a, and to further suppress breakage of the hollow fiber membrane 2. Here, the "state in which the protective member 7 is in close contact with the outer circumferential surface of the hollow fiber membrane bundle 3" is defined as a state in which md / L is an adhesion ratio of 0.90 or more, where L is the inner circumferential length of the protective member 7, m is the number of hollow fiber membranes 2 in contact with the protective member 7, and d is the outer diameter of the hollow fiber membranes 2 packed in the protective member 7. The higher the adhesion ratio, the more preferable, and md / L is more preferably 0.95 or more. In addition, when the inner diameter of the protective member 7 is sufficiently large compared to the outer diameter of the hollow fiber membranes 2, theoretically, when the maximum number of hollow fiber membranes 2 at the outermost periphery that can be in contact with the protective member 7 is M, L≒Md holds, and therefore the approximation md / L≒md / Md=m / M holds. In addition, the protective member 7 and the hollow fiber membrane 2 being in contact with each other means that the hollow fiber membrane 2 arranged at the outermost peripheral portion of the hollow fiber membrane bundle 3 and the protective member 7 are in contact with each other at at least one point in the thickness direction (longitudinal direction of the hollow fiber membrane 2) of the first adhesive fixing portion 5a and the second adhesive fixing portion 5b.

[0039] In the hollow fiber membrane module 1 of this embodiment, when the total opening area of ​​the through holes 6 is A, the total opening area of ​​the hollow parts of the hollow fiber membranes 2 is B, and the opening area of ​​the openings of the caps 8a and 8b is C, the relationship between A, B, and C is 0.5 or less. A / B is preferably 0.8

[0040] The hollow fiber membrane module of this embodiment has a filtered water volume (permeate volume) of 10 m 3 / h or more, and more preferably 12 m 3 / h or more, more preferably 16m 3 When the amount of filtered water per module is within the above range, the module can be suitably used as a final filtration membrane module for ultrapure water used for cleaning during the manufacture of silicon wafers, LSIs, liquid crystals, and the like.

[0041] [Manufacturing method for external pressure type hollow fiber membrane module] ​​The manufacturing method of the external pressure type hollow fiber membrane module of this embodiment is characterized in that a first straightening cylinder 11a and a second straightening cylinder 11b are attached to a housing 4, a hollow fiber membrane bundle 3 covered with a protective member 7 is inserted into the housing 4, a casting jig having at least one convex portion on its approximately disc-shaped surface which has an arc-shaped cross-sectional shape parallel to the approximately disc-shaped surface is attached so that the convex portion is positioned between the protective member 7 and the housing 4, the gap between the protective member 7 and the housing 4 is filled with a potting material and solidified, and then the casting jig is removed, thereby bringing the outer peripheral surface of the hollow fiber membrane bundle 3 into close contact with the protective member 7, and at least one through hole 6 having an arc-shaped cross-sectional shape in a direction perpendicular to the longitudinal direction of the housing 4 is opened on the outside of the protective member 7.

[0042] In the manufacturing method of the external pressure type hollow fiber membrane module of this embodiment, first, a predetermined number of hollow fiber membranes 2 are arranged into a bundle to produce a hollow fiber membrane bundle 3. Next, the opening at one end of each hollow fiber membrane 2 of the hollow fiber membrane bundle 3 is sealed with a sealant. Next, the first cylindrical member 9a and the second cylindrical member 9b are joined to both ends of the third cylindrical member 10 to form the housing 4, and the first flow straightening cylinder 11a and the second flow straightening cylinder 11b are attached to form the module case main body. Then, the outer circumferential surface of the hollow fiber membrane bundle 3 is wrapped with the protective member 7, and the hollow fiber membrane bundle 3 wrapped with the protective member 7 is inserted into the housing 4 so that the sealed end face side faces the second cylindrical member 9b side.

[0043] Thereafter, a cup-shaped adhesive jig (e.g., FIG. 3b) is attached to the first cylindrical member 9a, and a casting jig (e.g., FIG. 3a) having at least one convex part with an arc-shaped cross section parallel to the substantially disc-shaped surface on the substantially disc-shaped surface is attached to the second cylindrical member 9b so that the convex part of the casting jig is inserted between the outer circumferential surface of the hollow fiber membrane bundle 3 wrapped in the protective member 7 and the second cylindrical member 9b, and the first and second cylindrical members and the respective adhesive jigs are liquid-tightly constrained by a known method. At this time, the arc-shaped part of the jig having the convex part (e.g., FIG. 3a) is inserted, so that the outer circumferential surface of the hollow fiber membrane bundle 3 and the protective member 7 are in close contact with each other. The convex part of the casting jig is also a part that becomes a mold for the through-hole 6, and as described later, the casting jig is removed after the potting material has solidified to form the through-hole 6. If necessary, a cross plate (two plates joined or integrally formed so that the cross section perpendicular to the height direction is cross-shaped) may be installed as a bias control member in the hollow fiber membrane bundle 3 so that the height direction of the cross plate coincides with the longitudinal direction of the hollow fiber membrane bundle 3. The cross plate preferably has the same composition as the potting material. Next, the first adhesive fixing portion 5a and the second adhesive fixing portion 5b are formed by injecting a potting material into both ends of the housing 4. At this time, the opening of the hollow portion of the hollow fiber membrane bundle 3 on the second cylindrical member 9b side is blocked by the potting material. Thereafter, the through hole 6 is formed by removing the casting jig.

[0044] The hollow fiber membrane bundle 3 and the housing 4 can be bonded and fixed by centrifugal bonding, in which the housing 4 containing the hollow fiber membrane bundle 3 is bonded while rotating horizontally with the nozzles 12a and 12b facing vertically upward, or by static bonding, in which the housing 4 is arranged with its longitudinal direction vertical and the potting material is poured from the lower end of the housing 4. Centrifugal bonding can bond both ends of the hollow fiber membrane bundle 3 simultaneously, and the coating layer on the outer surface of the hollow fiber membrane bundle 3 can be made uniform, making it less likely to break the membrane, but it requires a large amount of capital investment and electricity to rotate at high speed. On the other hand, static bonding requires bonding one side at a time, so the time required for bonding increases, but does not require large capital investment and can be performed with a simple jig. After the potting material has hardened, it may be heated in an oven or the like as necessary to promote hardening.

[0045] Next, after confirming that the potting material in the housing 4 has hardened, the adhesive fixing portion forming container and the sealing material are removed from the first cylindrical member 9a (for example, by cutting the end of the first adhesive fixing portion 5a) to open the hollow portion of the hollow fiber membrane bundle 3. The adhesive fixing portion forming container and the casting jig are removed from the second cylindrical member 9b, to form the through hole 6 having an opening shape in an arc shape.

[0046] Finally, caps 8a, 8b are attached via O-rings 14 to both ends of the housing 4 to which the hollow fiber membrane bundle 3 is adhesively fixed, and then the caps are fastened with nuts 13. After that, a leak test, a trial run, etc. are carried out to confirm that the module has been manufactured according to the regulations, and the hollow fiber membrane module 1 is completed. EXAMPLES

[0047] Hereinafter, the present embodiment will be described with reference to specific examples and comparative examples, but the present embodiment is not limited to these.

[0048] The measurement and test methods used in the examples and comparative examples will be described below.

[0049] (1)Leak inspection The external pressure type hollow fiber membrane modules of the Examples and Comparative Examples were subjected to a leak inspection as follows. That is, after removing the caps on the side where the filtrate was collected (two in Comparative Example 1, one in the others), the module was immersed in a water tank and the inside of the hollow fiber membrane module was filled with water. Next, the cap on the side where the feed water was supplied (nozzle in Comparative Example 1) was sealed, and an air pressure of 0.3 MPa was applied from the nozzle for the discharge water. The end surface of the hollow fiber membrane on the side where the filtrate was collected (both end surfaces in Comparative Example 1, one end surface in the others) was observed, and the occurrence of leakage was investigated based on the presence or absence of continuous air bubbles generated from the hollow part.

[0050] (2) Flow Analysis For the examples and comparative examples, flow analysis was performed using the thermal fluid analysis software "PHOENICS" manufactured by CHAM (Concentoration Heat and Momentum Limited.) as simulation software and the Chen-Kim KE equation as calculation formula. The fluid was water at 20°C. As the simulation model of the embodiment, as shown in FIG. 5(a), a 3D model (1 / 2 model) was used in which a rectangular parallelepiped (1.284 m in the x direction × 0.088 m in the y direction × 0.223 m in the z direction) was drilled with a semi-cylindrical space having a radius equal to the inner diameter of the housing, with an inlet at one end and an outlet at the other end, and the rectangular parallelepiped was divided into 1 / 2 by a plane parallel to the XZ plane in FIG. 5(a). The simulation model was divided into 300 sections in the x direction (length direction), 30 sections in the y direction (depth direction), and 70 sections in the z direction (height direction), resulting in a total of 630,000 mesh cells. The number of SWEEPs (number of calculation repetitions) was set to 4,000, and the amount of water flowing in from the end (inlet) of the cylinder was set to 2.64 × 10 -3 m 3 The water pressure and velocity of the 1 / 2 model were simulated when the flow rate was 1 / s (1 / 2 model). The resistance values ​​of the water-containing porous body equivalent to the hollow fiber membrane bundle in the x, y, and z directions were set to 0.4, and the porosity was set to 0.7. In addition, in order to simulate the final filtration of ultrapure water, which is assumed to be an application of the external pressure type hollow fiber membrane module of this embodiment, total filtration (no discharged water volume) was performed. In the final filtration of ultrapure water, since the water to be treated itself is already very clear water, the flow rate of the discharged water is about several percent of the water to be treated, which can be said to be within the margin of error in the simulation. The simulation results of pressure and velocity are shown in Figures 6 and 7, where the pressure and velocity distributions are represented by shading, the direction of water flow is represented by arrows, and the magnitude of pressure and velocity is represented by the length of the arrows. In other words, the longer the arrows are, the greater the pressure and velocity.

[0051] [Production Example 1] The external pressure type hollow fiber membrane module (see FIG. 1) used in Examples 1 and 2 was produced as follows. A hollow fiber membrane bundle was formed by bundling 11,600 hollow fiber membranes made of polysulfone (manufactured by Asahi Kasei Corporation), and inserted into a polyethylene net (wire diameter 0.45 mm, aperture ratio 55%, equivalent to a protective member) formed into a cylindrical shape with an inner diameter of 138 mm. The hollow fiber membrane bundle inserted into the net was inserted into a housing having a first and second cylindrical member (inner diameter 168 mm) and a third cylindrical member (inner diameter 154 mm) with first and second straightening tubes (inner diameter 140 mm) attached to the inside, respectively. The first cylindrical member had a nozzle for discharge water with an inner diameter of 40 mm, and the second cylindrical member had a sealed nozzle. The hollow fiber membrane used had a molecular weight cutoff of 6000, an inner diameter of 0.6 mm, and an outer diameter of 1.00 mm. The hollow fiber membrane end on the first cylindrical member side was sealed with a sealant, and a cross plate (two plates 63 mm high x 136 mm wide x 5 mm thick joined together so that the cross section perpendicular to the height direction forms a cross shape) of the same composition as the potting material described below was placed in the hollow fiber membrane bundle as a bias control member, with the height direction of the cross plate aligned with the longitudinal direction of the hollow fiber membrane bundle. Furthermore, a cup for centrifugal casting, shaped as shown in Figure 3(b), was attached to the end of the first cylindrical member. A casting jig made of high-density polyethylene having the shape shown in FIG. 3(a) is attached to the end of the second cylindrical member, so that a partially arcuate opening having a width (opening area 800 mm) is formed after the potting material described later is cast. 2 , central angle: 80°, width: 8 mm) were formed in four places. Thereafter, a cup for centrifugal casting was attached in the same manner as the end of the first cylindrical member. Next, a tube for introducing the potting material was attached to each of the cups attached to the first and second cylindrical members. With the nozzle facing vertically upward, the housing was fixed horizontally to the centrifuge frame, and the housing was rotated horizontally to inject the potting material into the first and second cylindrical members of the housing. A two-component curing epoxy resin was used as the potting material. The rotation of the centrifuge was stopped when the curing reaction of the potting material progressed and fluidization stopped. The housing was removed from the centrifuge frame and heated to 90°C in an oven to completely cure. On the first cylindrical member side, the cup was removed, and the outer end of the hardened potting material was cut to open the hollow part of the hollow fiber membrane. On the second cylindrical member side, the cup and the casting jig were removed to open a partially arcuate opening with a width (opening area 800 mm 2 Four through holes having a diameter of 1 mm were formed. Next, caps with an opening diameter of 66 mm and the shape shown in FIG. 1 were fixed to both sides of the housing via O-rings and nuts to ensure liquid-tightness, thereby obtaining an external pressure type hollow fiber membrane module. The total opening area A of the through holes of this external pressure type hollow fiber membrane module is 3,200 mm 2 The total opening area B of the hollow fiber membrane is 3,280 mm 2 , the opening area C of the cap opening is 3,421 mm 2 The area S obtained by subtracting the area occupied by the net (protective member) from the internal cross-sectional area of ​​the housing (second cylindrical member) is 7,210 mm 2 Therefore, A / B was 0.98, C / B was 1.04, and A / S was 0.44.

[0052] [Production Example 2] An external pressure type hollow fiber membrane module (see FIG. 1) used in Example 5 was produced in the same manner as in Production Example 1, except that a hollow fiber membrane having a molecular weight cutoff of 10,000, an inner diameter of 0.6 mm, and an outer diameter of 1.00 mm was used.

[0053] [Example 1] The external pressure type hollow fiber membrane module of Production Example 1 was attached to the evaluation device shown in Fig. 4(a) so that the first cylindrical member side was on the vertical upper side and the second cylindrical member side was on the vertical lower side (water tank, pump, etc. are omitted in Fig. 4(a)). 3 Supply water at a flow rate of 0.4 m from the nozzle. 3 The wastewater was discharged at a flow rate of 12 m 3 The flow rate of the filtered water was 1.07 m / s at the through-hole, 1.02 m / s at the hollow fiber membrane, 1.00 m / s at the cap opening on the feed water side, and 0.97 m / s at the cap opening on the filtered water side. The system was operated continuously under the above operating conditions, and a leak test was conducted once a day for about 5 minutes. Even after one year, no leaks due to breakage of the hollow fiber membrane occurred.

[0054] [Example 2] A continuous operation was carried out in the same manner as in Example 1 except that the operating conditions shown in Table 1 were used, and a leak test was carried out once a day for about 5 minutes. Since no leaks due to breakage of the hollow fiber membrane had occurred 30 days after the start of operation, the amount of water supplied was increased by 30% from the 31st day and operation was continued (water supply amount 20.6 m 3 / h, discharge water amount 0.6m 3 / h, permeated water amount 20m 3 / h), and on the 91st day, a leak was confirmed due to the breakage of one hollow fiber membrane. After that, the broken hollow fiber membrane was repaired and operation was continued, but no leaks occurred until the 150th day, so operation was terminated.

[0055] [Example 3] A calculation model shown in Fig. 5(a) was constructed and a flow analysis was performed as a simulation model following the specifications of the external pressure type hollow fiber membrane module of Production Example 1. Fig. 5(b) is a diagram showing the structure near the inlet. As in Manufacturing Example 1, the opening area of ​​the through hole (see FIG. 5(b)) having a partially arcuate cross section with a width was 800 mm 2 The opening inner diameter of inlet 22 and outlet 21 was set to 66 mm, and 11,600 hollow fiber membranes with an inner diameter of 0.6 mm and an outer diameter of 1.00 mm were used, and the calculation was made assuming total filtration (no discharged water volume). The area S obtained by subtracting the internal occupied area of ​​the net (protective member) from the internal cross-sectional area of ​​the housing (second cylindrical member) was calculated as 7,210 mm by subtracting the internal cross-sectional area of ​​the net with an inner diameter of 138 mm filled with the hollow fiber membranes from the exclusive cross-sectional area calculated from the diameter of 168 mm, which corresponds to the internal diameter of the second cylindrical member. 2 It was calculated that: The linear speeds at each point, A / B, C / B, and A / S, are shown in Table 1. The results of the pressure distribution and velocity distribution are shown in Figures 6(a) and 6(b), respectively. It can be seen that the slope of both the pressure distribution and the velocity distribution is gentle, and the pressure loss is small.

[0056] [Example 4] The opening area of ​​a through hole with a circular cross section is 750 mm 2 A flow analysis was carried out in the same manner as in Example 3, except that the inner opening diameter of the inlet 22 and the outlet 21 was 52.5 mm (central angle: 75°, width: 8 mm). The linear speeds at each point, A / B, C / B, and A / S, are shown in Table 1. The results of the pressure distribution and velocity distribution are shown in Figures 7(a) and 7(b), respectively. Although the gradient of the distribution was larger than that of Example 3, the distribution was still practical.

[0057] [Example 5] A continuous operation was carried out in the same manner as in Example 1 except that the operating conditions shown in Table 1 were used, and a leak test was carried out once a day for about 5 minutes. No leaks due to hollow fiber membrane ruptures occurred for the first three days after the start of operation, but on the fourth day, leaks were confirmed due to the rupture of four hollow fiber membranes. After that, the ruptured hollow fiber membranes were repaired and operation was continued, but on the 12th day, leaks were confirmed due to the rupture of three new hollow fiber membranes separate from the one that had ruptured on the fourth day, and operation was terminated.

[0058] [Comparative Example 1] The hollow fiber membrane module disclosed in Example 1 of Patent Document 1 was manufactured and attached to the evaluation device shown in Fig. 4(b) so that the pipe 10a was on the vertical upper side and the pipe 11a was on the vertical lower side, similarly to Example 1 of Patent Document 1 (water tank, pump, etc. are omitted in Fig. 4(b)). In this hollow fiber membrane module, the gap portion between the outer wall of the straightening cylinder 28 and the inner wall of the body 13, which has a concentric cross-sectional shape in a direction perpendicular to the longitudinal direction of the housing, was regarded as the portion corresponding to the through-hole in the external pressure type hollow fiber membrane module of the Example. The dimensions of each part were calculated by proportional calculation from the values ​​disclosed in Patent Document 1 and Figures 1 and 3 of Patent Document 1. As a result, the outer and inner diameters of the concentric circular opening of the above-mentioned gap part were 154 mm and 149.6 mm, respectively, and the area equivalent to the total opening area A of the through holes was 1,049 mm. 2 Similarly, since the diameter of the hollow fiber membrane is 0.6 mm and the number of fibers is 11,600, the total opening area B of the hollow fiber membrane is 3,280 mm 2 In addition, the opening diameter of the cap 10, which corresponds to the drainage discharge side cap in the present invention, is 20 mm by proportional calculation, so the opening area C on the drainage side is 314 mm 2 In the present invention, the diameter of the opening 21a of the lower nozzle 21, which corresponds to the cap on the water supply side, is 58 mm, so that the opening area C on the water supply side is 2,642 mm 2 The area S obtained by subtracting the area occupied by the protective member (net-shaped drift suppression portion 29) from the internal cross-sectional area of ​​the housing (header portion 15) was calculated as 4,053 mm, which was calculated from the inner diameter of the header portion 15, 162 mm, and the outer diameter of the drift suppression portion 29, 145.2 mm, calculated by proportional calculation. 2 It became. The linear speeds at each point, A / B, C / B, and A / S, are shown in Table 1. This membrane module was continuously operated under the same operating conditions as in Example 2, and a leak test was carried out once a day for about 5 minutes. Since no leaks due to breakage of the hollow fiber membrane had occurred 30 days after the start of operation, the amount of water supplied was increased by 30% from the 31st day and operation was continued (water supply amount 20.6 m 3 / h, discharge water amount 0.6m 3 / h, permeated water amount 20m 3 / h), and on the 49th day, a leak was confirmed due to the breakage of one hollow fiber membrane. After that, the broken hollow fiber membrane was repaired and operation was continued, but on the 77th day, another leak was confirmed due to the breakage of one hollow fiber membrane, and operation was terminated.

[0059] [Comparative Example 2-1] The external pressure type hollow fiber membrane module disclosed in Example 1 of Patent Document 3 was manufactured by the manufacturing method described in the same patent document, and was attached to the evaluation device shown in Figure 4(a) so that the pipe 10a was on the vertical upper side and the pipe 11a was on the vertical lower side, similarly to Example 1 of Patent Document 3 (water tank, pump, etc. are omitted in Figure 4(a)). However, the hollow fiber membranes used had an outer diameter of 1.0 mm and an inner diameter of 0.6 mm, the same as in the above Manufacturing Example 1, and the number of hollow fiber membranes was 5,400, following the exclusive area (outer diameter basis) of the hollow fiber membranes in a cross section perpendicular to the longitudinal direction in the membrane module of Example 1 of Patent Document 3. The dimensions of each part were calculated by proportional calculation from the values ​​disclosed in Patent Document 3 and Figure 1 of Patent Document 3. Since there are five through holes with a circular opening shape of 11 mm in diameter, the total opening area A of the through holes is 475 mm 2 The inner diameter of the hollow fiber membrane was 0.6 mm, and the number of fibers was 5,400. As a result, the total opening area B of the hollow fiber membrane was 1,527 mm 2 The diameter of the cap opening is 31.6 mm, so the area of ​​the cap opening C is 784 mm 2In addition, since the inner diameter of the housing (first cylindrical member 51) is 96.8 mm by proportional calculation, the area S obtained by subtracting the inner occupied area of ​​the protective member (net-shaped protective member 8, inner diameter 80 mm) from the inner cross-sectional area of ​​the housing (first cylindrical member 51) is 2,333 mm 2 It was calculated that: In the same manner as in Example 1 of Patent Document 3, 3 Supply water at a flow rate of 0.4 m from the nozzle. 3 The wastewater was discharged at a flow rate of 3.1 m 3 The system was operated to obtain a filtered water flow rate of 1000 / h. The linear speeds at each point, A / B, C / B, and A / S, are shown in Table 1. The above operating conditions were maintained while the system was operated continuously, and a leak test was performed once a day for about 5 minutes each time. After 6 months, a leak was confirmed due to the breakage of one hollow fiber membrane. After that, the broken hollow fiber membrane was repaired and operation was continued, and after 7 months, a leak was confirmed due to the breakage of another hollow fiber membrane other than the one broken after 6 months. After that, the broken hollow fiber membrane was repaired and operation was continued, and after 9 months, a leak was confirmed due to the breakage of two hollow fiber membranes other than the hollow fiber membrane broken after 6 months and 7 months, and operation was terminated. The hollow fiber membrane module was disassembled to check the location of the leak, and all of the breakages of the four hollow fiber membranes occurred within a range of 20 to 50 mm in the longitudinal direction from the inner end of the adhesive fixing part (potting part) near the through hole.

[0060] [Comparative Example 2-2] Since the external pressure type hollow fiber membrane module of Comparative Example 2-1 had a leak in a shorter time than the external pressure type hollow fiber membrane module of Example 1 of Patent Document 3, a calculation model shown in Fig. 8(a) was constructed as a simulation model following the specifications of the external pressure type hollow fiber membrane module of Comparative Example 2-1, and a flow analysis was performed. Fig. 8(b) is a diagram showing the structure near the inlet. As shown in FIG. 8(a), a rectangular parallelepiped (1.375 m in the x direction × 0.052 m in the y direction × 0.152 m in the z direction) was drilled with a semi-cylindrical space having a radius equal to the inner diameter of the housing, with an inlet 32 ​​at one end and an outlet 31 at the other end. A 3D model (1 / 2 model) was used, which was divided into 1 / 2 by a plane parallel to the XZ plane in FIG. 8(a). As in Comparative Example 2-1, the inner diameter of the housing (first cylindrical member 51) is 96.8 mm by proportional calculation, so the area S obtained by subtracting the inner occupied area of ​​the protective member (net-shaped protective member 8, inner diameter 80 mm) from the inner cross-sectional area of ​​the housing (first cylindrical member 51) is 2,333 mm 2 It was calculated that: The simulation model was divided into 340 sections in the x direction (length direction), 20 sections in the y direction (depth direction), and 55 sections in the z direction (height direction), resulting in a total of 374,000 mesh cells. The number of SWEEPs was 2,000, and the amount of water flowing in from the end of the cylinder (inlet 32) was 4.86 × 10 -4 m 3 / s (1 / 2 model, 3.5m, same as Comparative Example 2-1) 3 The water pressure and velocity of the 1 / 2 model were simulated when the flow rate was 1 / 2 sq.m. / h. The resistance values ​​of the water-containing porous body equivalent to the hollow fiber membrane bundle in the x, y, and z directions were set to 0.4, and the porosity was set to 0.7. The results of the velocity distribution are shown in Figures 9(a) and 9(b). Figure 9(a) is a distribution diagram viewed from the longitudinal direction of the simulation model, and Figure 9(b) is a distribution diagram viewed from the direction perpendicular to the longitudinal direction of the simulation model. Figures 9(a) and 9(b) show that the water supplied from the through-hole was in a jet state. The cause of this jet state is thought to be a lack of the through-hole (opening area). In addition, in Example 1 of Patent Document 3, no leaks occurred even after one year of continuous operation, whereas in Comparative Example 2-1, the cause of the leaks was thought to be the difference in durability per membrane filament against the jet. That is, the hollow fiber membrane used in Example 1 of Patent Document 3 had an outer diameter / inner diameter of 1.35 mm / 0.75 mm (cross-sectional area of ​​the thick part = 0.99 mm 2), whereas in Comparative Example 2-1, the thickness was 1.00 mm / 0.60 mm (cross-sectional area of ​​thick part = 0.5 mm 2 ), which is roughly half the cross-sectional area of ​​the thick portion of the hollow fiber membrane of Comparative Example 2-1. It is believed that the hollow fiber membrane of Comparative Example 2-1 lacked durability against the vibrations caused by the above-mentioned jet flow.

[0061] [Comparative Example 3] A calculation model shown in Fig. 10(a) was constructed and a flow analysis was performed as a simulation model following the specifications of the external pressure type hollow fiber membrane module disclosed in Example 1 of Patent Document 2. Fig. 10(b) is a diagram showing the structure near the inlet. As shown in FIG. 10(a), a semi-cylindrical space with a radius equal to the inner diameter of the housing was drilled into a rectangular parallelepiped (1.284 m in the x direction × 0.088 m in the y direction × 0.223 m in the z direction), with an inlet 42 at one end and an outlet 41 at the other end. A 3D model (1 / 2 model) was used, which was divided into 1 / 2 by a plane parallel to the XZ plane in FIG. 10(a). The simulation model was divided into 300 sections in the x direction (length direction), 30 sections in the y direction (depth direction), and 70 sections in the z direction (height direction), resulting in a total of 630,000 mesh cells. The dimensions of each part were calculated by proportional calculation from the values ​​disclosed in Patent Document 2 and Figure 1 of Patent Document 2. A circular opening with an outer diameter of 160 mm and an inner diameter of 151.4 mm was considered to correspond to the through hole. Since the outer diameter of the hollow fiber membrane is disclosed as 1.2 mm, the inner diameter was considered to be 0.72 mm by applying the inner / outer diameter ratio of the hollow fiber membrane used in the above example, and 10,800 pieces were used as disclosed. The inner diameter of the opening of inlet 42 and outlet 41 was 39 mm. In addition, the area S obtained by subtracting the internal occupied area of ​​the protective member (outer layer net tube 3) from the internal cross-sectional area of ​​the housing was calculated to be 3,135 mm by subtracting the occupied cross-sectional area corresponding to the outer diameter of the outer layer net tube 3 (calculated to be 147 mm by proportional calculation) from the occupied cross-sectional area corresponding to the head inner diameter of 160 mm. The number of SWEEPs was 4,000, and the amount of water flowing in from the end (inlet) of the cylinder was 2.64×10 -3 m3 The water pressure and velocity of the 1 / 2 model were simulated when the flow rate was 1 / s (1 / 2 model). The resistance values ​​of the water-containing porous body equivalent to the hollow fiber membrane bundle in the x, y, and z directions were set to 0.4, and the porosity was set to 0.7. The linear speeds at each point, A, B, C, A / B, C / B, and A / S, are shown in Table 1. The results of the pressure distribution and velocity distribution are shown in Figures 11(a) and 11(b), respectively. Compared to Examples 3 and 4, the pressure inside the supply section (corresponding to the inside of the sealing section 4 of the cap section 15 in Patent Document 2) and inside the filtrate collection section (corresponding to the vicinity of the permeate outlet 14 of the cap section 16 in Patent Document 2) was high, and a large pressure loss was observed when the water to be treated was supplied to the hollow fiber membrane bundle and after the filtrate was discharged from the hollow fiber membrane bundle. Furthermore, the distribution of maximum pressure values ​​was observed inside the supply section, suggesting that a force was acting on the hollow fiber membrane bundle to push it upward (to the left in Figure 11(a)). In other words, a force was generated that pushed the entire hollow fiber membrane bundle upward (to the left in Figure 11(a)), which raises concerns about buckling of the fiber bundle.

[0062] [Comparative Example 4] In the calculation model of Comparative Example 3, since the concern of buckling was predicted as described above, a calculation model was constructed in which baffle plate 53 was further provided in the calculation model of Comparative Example 3 as shown in Fig. 12(a) and 12(b), and flow analysis was performed under the same conditions as in Comparative Example 3. Baffle plate 53 was modeled with 16 holes of 25 mm diameter opened along the periphery (8 holes in the calculation model because it was a 1 / 2 calculation model) as equivalent to the through holes in the embodiment. As in Comparative Example 3, the area S obtained by subtracting the internal occupied area of ​​the protective member (outer layer net tube 3) from the internal cross-sectional area of ​​the housing was calculated to be 3,135 mm by subtracting the occupied cross-sectional area corresponding to the outer diameter of the outer layer net tube 3 (calculated to be 147 mm by proportional calculation) from the occupied cross-sectional area corresponding to the head inner diameter of 160 mm. The linear speeds at each point, A, B, C, A / B, A / B, and A / S, are shown in Table 1. The results of the pressure distribution and velocity distribution are shown in Figures 13(a) and 13(b), respectively. The distribution of the maximum pressure values ​​where buckling is a concern moved from the surface corresponding to the end face of the sealing section 4 inside the supply section to the baffle plate, but the pressure inside the supply section and the filtrate sampling section was high as in Comparative Example 3, and the tendency for large pressure loss to occur was similar.

[0063] [Comparative Example 5] An external pressure type hollow fiber membrane module was manufactured which differed from Comparative Example 1 only in the hollow fiber membrane (the hollow fiber membrane was the same as that used in Manufacturing Example 2). Continuous operation was carried out in the same manner as in Example 5, and a leak test was carried out once a day for approximately 5 minutes. On the first day after the start of operation, seven hollow fiber membranes broke, and on the second day a total of 13 hollow fiber membranes broke, causing leaks, and operation was terminated.

[0064] [Table 1] [Industrial Applicability]

[0065] The external pressure type hollow fiber membrane module of the present invention is highly durable, has excellent uniformity in the pressure distribution and velocity distribution of the fluid passing through it, and has little pressure loss, and therefore can be suitably used particularly as a final filtration membrane module for ultrapure water used for cleaning during the production of silicon wafers, LSIs, liquid crystals, etc. [Explanation of symbols]

[0066] 1. External pressure type hollow fiber membrane module 2. Hollow fiber membrane 3 Hollow fiber membrane bundle 4. Housing 5a First adhesive fixing part 5b Second adhesive fixing part 6, 23, 33 Through holes 7 Protective materials 8 Cap 9a First cylindrical member 9b Second tubular member 10 Third tubular member 11a First straightening cylinder 11b Second straightening cylinder 12 Nozzles 13 Nut 14 O-ring 21, 31, 41, 51 outlets 22, 32, 42, 52 intlets 53 Baffle Plate

Claims

1. A hollow fiber membrane bundle including a plurality of hollow fiber membranes, each of which has one end closed and the other end open; a housing that is a cylindrical body having at least one nozzle on a side surface and that accommodates the hollow fiber membrane bundle such that the closed end of the hollow fiber membrane and the open end of the hollow fiber membrane face both ends of the cylindrical body in the longitudinal direction; a first straightening tube mounted between the open end of the hollow fiber membrane bundle and an end of the housing; a second straightening tube mounted between the closed end of the hollow fiber membrane bundle and the end of the housing; a first adhesive fixing portion that adhesively fixes the hollow fiber membranes to each other and the hollow fiber membrane bundle to the inner wall of the housing at the open end side of the hollow fiber membranes; a second adhesive fixing portion that adhesively fixes the hollow fiber membranes to each other and the hollow fiber membrane bundle to the inner wall of the housing at the closed end side of the hollow fiber membranes, and has at least one through hole parallel to the longitudinal direction of the housing on the outer periphery of the hollow fiber membrane bundle; a protective member that covers the entire outer circumferential surface of the hollow fiber membrane bundle in a state of being in close contact with the outer circumferential surface of the hollow fiber membrane bundle in at least one of an end region of at least a predetermined length from the first adhesive fixing part toward the second adhesive fixing part and an end region of at least a predetermined length from the second adhesive fixing part toward the first adhesive fixing part; a cap having an opening and attached to both ends of the housing in the longitudinal direction; the through hole is disposed adjacent to an outer peripheral surface of the hollow fiber membrane bundle, and a cross-sectional shape of the through hole in a direction perpendicular to the longitudinal direction of the housing is a partial arc shape having a width, a ratio (A / S) of a sum A of opening areas of the through holes to an area S obtained by subtracting an area defined by an outer peripheral surface of the protective member from an area defined by an inner wall of the housing in a cross section perpendicular to the longitudinal direction of the housing is 0.4 to 0.6; the sum of the opening areas of the through holes is A, the sum of the opening areas of the hollow parts of the hollow fiber membrane is B, and the opening area of ​​the opening of the cap is C, the relationship between A, B, and C is 0.9<A / B<1.1 and 0.5<C / B<1.5, The protective member is provided between the hollow fiber membrane bundle and the through hole so as to be in contact with the hollow fiber membrane bundle and the through hole. An external pressure type hollow fiber membrane module.

2. 2. The external pressure type hollow fiber membrane module according to claim 1, wherein the protective member is disposed across the first adhesive fixing portion and the second adhesive fixing portion.

3. 3. The external pressure type hollow fiber membrane module according to claim 1, wherein the protective member is a net-like member formed into a cylindrical shape.

4. 4. The external pressure type hollow fiber membrane module according to claim 3, wherein the net-like member has a wire diameter of 0.2 to 1.5 mm and an opening rate of 40 to 90%.

5. 5. The external pressure type hollow fiber membrane module according to claim 1, wherein the opening of at least one of the caps is structured to be sealed and fixed with a packing having the same inner diameter as the opening.

6. A method for producing an external pressure type hollow fiber membrane module according to any one of claims 1 to 5, comprising the steps of: a first straightening tube and a second straightening tube are attached to the housing; a hollow fiber membrane bundle covered with the protective member is inserted into the housing; a casting jig having at least one convex portion on a substantially disc-shaped surface, the cross-sectional shape of which is a partial arc having a width in a cross section parallel to the substantially disc-shaped surface, is attached between the protective member and the housing so that the convex portion is positioned; a gap between the protective member and the housing is filled with a potting material and solidified, and then the casting jig is removed, thereby bringing the outer peripheral surface of the hollow fiber membrane bundle and the protective member into a tightly adhered state; and at least one through hole, the cross-sectional shape of which is a partial arc having a width in a cross-sectional shape in a direction perpendicular to the longitudinal direction of the housing, is opened on the outside of the protective member.

Images