Method for manufacturing hollow fiber membrane element, hollow fiber membrane element, and hollow fiber membrane module

Abstract

This method for manufacturing a hollow fiber membrane element comprises: a membrane bundle formation step for forming a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled in a cylindrical shape; a first fixing step for fixing a first membrane bundle end, which is one end of the hollow fiber membrane bundle, with a resin; and a second fixing step for fixing a second membrane bundle end, which is the other end of the hollow fiber membrane bundle, with a resin. In the first fixing step, the resin for fixing the first membrane bundle end is cured under cooling. This hollow fiber membrane element comprises: a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled in a cylindrical shape; a first fixing part that is made of a resin and fixes a first membrane bundle end, which is one end of the hollow fiber membrane bundle; and a second fixing part that is made of a resin and fixes a second membrane bundle end, which is the other end of the hollow fiber membrane bundle. The coefficient of variation of the outer diameters of the plurality of hollow fiber membranes is 3.5 or less.

Description

Method for manufacturing hollow fiber membrane element, hollow fiber membrane element, and hollow fiber membrane module

[0001] The present disclosure relates to a method for manufacturing a hollow fiber membrane element, a hollow fiber membrane element, and a hollow fiber membrane module.

[0002] Conventionally, a hollow fiber membrane module including a hollow fiber membrane element in which both ends of a bundle of a plurality of hollow fiber membranes bundled in a cylindrical shape are fixed, and a housing that houses this hollow fiber membrane element is known (for example, see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2003-038904

[0004] When the present disclosure inventors measured the pressure loss of a liquid in such a hollow fiber membrane module, the pressure loss of the liquid was considerably larger than the ideal value.

[0005] Therefore, an object of the present disclosure is to provide a method for manufacturing a hollow fiber membrane element, a hollow fiber membrane element, and a hollow fiber membrane module that can reduce the pressure loss of a liquid.

[0006] The present disclosure inventors further conducted research to solve the above problems and obtained the following findings. When measuring the outer diameters of a plurality of hollow fiber membranes in a hollow fiber membrane element, the coefficient of variation in the outer diameters of the plurality of hollow fiber membranes in the hollow fiber membrane element was larger than the coefficient of variation in the outer diameters of the plurality of spun hollow fiber membranes. This is considered to be due to the following factors. The manufacturing of a hollow fiber membrane element is performed by inserting the ends of a hollow fiber membrane bundle into a cylindrical container, injecting a resin for fixing the hollow fiber membrane bundle (hereinafter sometimes referred to as a fixing resin) into the cylindrical container, and curing the fixing resin. However, since the resin becomes high temperature due to heating during curing or the resin generates heat, the hollow fiber membrane bundle thermally contracts due to the influence of the heat of the resin. At this time, due to the state of each hollow fiber membrane, the interval between the hollow fiber membranes, the position of the hollow fiber membranes in the cylindrical container, etc., variations occur in the degree of thermal contraction among the plurality of hollow fiber membranes. As a result, it is considered that the variation in the outer diameters becomes large among the plurality of hollow fiber membranes, and the coefficient of variation in the outer diameters of the plurality of hollow fiber membranes in the hollow fiber membrane element becomes large.

[0007] If the coefficient of variation of the outer diameter of multiple hollow fiber membranes in a hollow fiber membrane element is large, a large flow deviation occurs in the liquid flowing between the multiple hollow fiber membranes, resulting in a large pressure loss of the liquid as it passes through the multiple hollow fiber membranes, and thus a large liquid pressure loss for the entire hollow fiber membrane module. Therefore, it has been found that by reducing the coefficient of variation of the outer diameter of multiple hollow fiber membranes in a hollow fiber membrane element, the flow deviation of the liquid flowing between the multiple hollow fiber membranes can be mitigated, and the liquid pressure loss can be reduced. This disclosure is based on this finding.

[0008] [1] A method for manufacturing a hollow fiber membrane element according to the present disclosure comprises a membrane bundle forming step of forming a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled together in a cylindrical shape, a first fixing step of fixing a first membrane bundle end, which is one end of the hollow fiber membrane bundle, with a resin, and a second fixing step of fixing a second membrane bundle end, which is the other end of the hollow fiber membrane bundle, with a resin, wherein in the first fixing step the resin used to fix the first membrane bundle end is cured while being cooled.

[0009] In this method for manufacturing hollow fiber membrane elements, in the first fixing step, the resin used to fix the end of the first membrane bundle is cured while being cooled, thereby fixing the end of the first membrane bundle with the resin. As a result, the total amount of heat generated when the resin hardens is reduced, which reduces the degree of thermal contraction of the hollow fiber membrane bundle due to the heat of the resin, reducing the variation in the degree of thermal contraction among multiple hollow fiber membranes and thus reducing the variation in outer diameter among multiple hollow fiber membranes. Therefore, the coefficient of variation in the outer diameter of multiple hollow fiber membranes in the manufactured hollow fiber membrane element is reduced. As a result, when a liquid is flowed between multiple hollow fiber membranes, the uneven flow of the liquid flowing between the multiple hollow fiber membranes is mitigated, thereby reducing the pressure loss of the liquid as it passes between the multiple hollow fiber membranes.

[0010] [2] In the method for manufacturing a hollow fiber membrane element described in [1], in the first fixing step, the end of the first membrane bundle may be inserted into a cylindrical container, resin may be injected into the cylindrical container, and the resin may be cured while the cylindrical container is cooled. In this method for manufacturing a hollow fiber membrane element, in the first fixing step, the end of the first membrane bundle is inserted into a cylindrical container, resin may be injected into the cylindrical container, and the resin may be cured while the cylindrical container is cooled. This makes it possible to cure the resin while cooling it when fixing the end of the first membrane bundle with the resin.

[0011] [3] In the method for manufacturing a hollow fiber membrane element described in [1], in the first fixing step, the end of the first membrane bundle may be inserted into the first cylindrical container, and while rotating the first cylindrical container and the hollow fiber membrane bundle with the central part in the longitudinal direction of the hollow fiber membrane bundle as the axis, resin may be supplied between the end of the first membrane bundle and the central part of the hollow fiber membrane bundle, and the resin may be cured while cooling the first cylindrical container. In this method for manufacturing a hollow fiber membrane element, in the first fixing step, the end of the first membrane bundle may be inserted into the first cylindrical container, and while rotating the first cylindrical container and the hollow fiber membrane bundle with the central part in the longitudinal direction of the hollow fiber membrane bundle as the axis, resin may be supplied between the end of the first membrane bundle and the central part of the hollow fiber membrane bundle, and the resin may be cured while cooling the first cylindrical container. This makes it possible to cure the resin while cooling it when fixing the end of the first membrane bundle with the resin.

[0012] [4] In the method for manufacturing a hollow fiber membrane element described in [2] or [3], the cylindrical container may be cooled by air cooling by blowing air onto it in the first fixing step. In this method for manufacturing a hollow fiber membrane element, the cylindrical container is cooled by air cooling by blowing air onto it. Therefore, the cylindrical container can be cooled by simple means.

[0013] [5] In the method for manufacturing a hollow fiber membrane element described in [2] or [3], the cylindrical container may be cooled by water cooling by supplying a cooling liquid to the cylindrical container in the first fixing step. In this method for manufacturing a hollow fiber membrane element, the cylindrical container is cooled by water cooling by supplying a cooling liquid to the cylindrical container, so the cylindrical container can be cooled efficiently.

[0014] [6] In the method for manufacturing a hollow fiber membrane element described in [1], in the membrane bundle formation step, a hollow fiber membrane bundle may be formed by winding a hollow fiber membrane sheet into a cylindrical shape while applying resin to the surface of a hollow fiber membrane sheet in which a plurality of hollow fiber membranes are connected in a curtain-like manner by a plurality of connecting threads. In this method for manufacturing a hollow fiber membrane element, in the membrane bundle formation step, a hollow fiber membrane bundle is formed by winding a hollow fiber membrane sheet into a cylindrical shape while applying resin to the surface of a hollow fiber membrane sheet in which a plurality of hollow fiber membranes are connected in a curtain-like manner by a plurality of connecting threads. This makes it possible to easily form a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled into a cylindrical shape.

[0015] [7] In the method for manufacturing a hollow fiber membrane element described in [6], in the first fixing step, the end of the first membrane bundle may be cooled by air cooling by blowing air onto the end of the first membrane bundle. In this method for manufacturing a hollow fiber membrane element, in the first fixing step, the end of the first membrane bundle is cooled by air cooling by blowing air onto the end of the first membrane bundle. This allows the resin that fixes the end of the first membrane bundle to be cooled and cured, thereby fixing the end of the first membrane bundle with the resin.

[0016] [8] In the method for manufacturing a hollow fiber membrane element described in any of [1] to [7], the material of the plurality of hollow fiber membranes is a polyolefin resin, and the resin used to fix the end of the first membrane bundle may be any one of epoxy resin, urethane resin, and olefin resin. In this method for manufacturing a hollow fiber membrane element, since the material of the plurality of hollow fiber membranes is a polyolefin resin and the resin used to fix the end of the first membrane bundle is any one of epoxy resin, urethane resin, and olefin resin, the end of the first membrane bundle can be properly fixed.

[0017] [9] In the method for manufacturing a hollow fiber membrane element described in any of [2] to [5], the resin used to fix the end of the first membrane bundle is a thermosetting resin, and in the first fixing step, a curing agent that promotes the hardening of the resin may be injected into the cylindrical container along with the resin. In this method for manufacturing a hollow fiber membrane element, the resin used to fix the end of the first membrane bundle is a thermosetting resin, and in the first fixing step, a curing agent that promotes the hardening of the resin is injected into the cylindrical container along with the resin. As a result, the end of the first membrane bundle hardens earlier, further reducing the total amount of heat generated when the resin hardens. This further reduces the coefficient of variation of the outer diameter of the multiple hollow fiber membranes in the manufactured hollow fiber membrane element.

[0018]

[10] In the method for manufacturing a hollow fiber membrane element described in any of [1] to [9], in the first fixing step, the resin used to fix the ends of the first membrane bundle may be cured while cooling the resin so that the coefficient of variation of the outer diameter of the multiple hollow fiber membranes is 3.5 or less. In this method for manufacturing a hollow fiber membrane element, in the first fixing step, the resin used to fix the ends of the first membrane bundle is cured while cooling the resin so that the coefficient of variation of the outer diameter of the multiple hollow fiber membranes is 3.5 or less. As a result, the liquid pressure loss in the manufactured hollow fiber membrane element can be reduced and the performance can be stabilized.

[0019]

[11] In the method for manufacturing a hollow fiber membrane element described in any of [1] to

[10] , in the second fixing step, the resin used to fix the end of the second membrane bundle may be cured while being cooled. In this method for manufacturing a hollow fiber membrane element, in the second fixing step, the resin used to fix the end of the second membrane bundle is cured while being cooled, thereby fixing the end of the second membrane bundle with the resin. As a result, the total amount of heat generated when the resin hardens is reduced, which reduces the degree of thermal contraction of the hollow fiber membrane bundle due to the heat of the resin, reduces the variation in the degree of thermal contraction among multiple hollow fiber membranes, and further reduces the variation in outer diameter among multiple hollow fiber membranes. Therefore, the coefficient of variation of the outer diameter of multiple hollow fiber membranes in the manufactured hollow fiber membrane element becomes even smaller. As a result, when a liquid is flowed between multiple hollow fiber membranes, the uneven flow of the liquid flowing between the multiple hollow fiber membranes is further reduced, and the pressure loss of the liquid as it passes between the multiple hollow fiber membranes can be further reduced.

[0020] In the method for manufacturing a hollow fiber membrane element described in

[12] [2], in the second fixing step, the end of the second membrane bundle may be inserted into a cylindrical container, resin may be injected into the cylindrical container, and the resin may be cured while the cylindrical container is cooled. In this method for manufacturing a hollow fiber membrane element, in the second fixing step, the end of the second membrane bundle is inserted into a cylindrical container, resin may be injected into the cylindrical container, and the resin may be cured while the cylindrical container is cooled. This makes it possible to cure the resin while cooling it when fixing the end of the second membrane bundle with the resin.

[0021] In the method for manufacturing a hollow fiber membrane element described in

[13] [3], in the second fixing step, the end of the second membrane bundle may be inserted into the second cylindrical container, and while rotating the second cylindrical container and the hollow fiber membrane bundle with the central part in the longitudinal direction of the hollow fiber membrane bundle as the axis, resin may be supplied between the end of the second membrane bundle and the central part of the hollow fiber membrane bundle, and the resin may be cured while cooling the second cylindrical container. In this method for manufacturing a hollow fiber membrane element, in the second fixing step, the end of the second membrane bundle is inserted into the second cylindrical container, and while rotating the second cylindrical container and the hollow fiber membrane bundle with the central part in the longitudinal direction of the hollow fiber membrane bundle as the axis, resin may be supplied between the end of the second membrane bundle and the central part of the hollow fiber membrane bundle, and the resin may be cured while cooling the second cylindrical container. This makes it possible to cure the resin while cooling it when fixing the end of the second membrane bundle with the resin.

[0022]

[14] In the method for manufacturing a hollow fiber membrane element described in any of [1] to

[13] , a cutting step may be further provided after the first fixing step and the second fixing step, in which the ends of the first membrane bundle end and the ends of the second membrane bundle end are cut. In this method for manufacturing a hollow fiber membrane element, the ends of the first membrane bundle end and the ends of the second membrane bundle end are cut after the first fixing step and the second fixing step. Therefore, even if a small amount of resin enters the hollow parts of the multiple hollow fiber membranes in the first fixing step and the second fixing step, the hollow parts of the multiple hollow fiber membranes can be opened.

[0023]

[15] The hollow fiber membrane element according to the present disclosure comprises a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled in a cylindrical shape, a first fixing part made of resin for fixing a first membrane bundle end which is one end of the hollow fiber membrane bundle, and a second fixing part made of resin for fixing a second membrane bundle end which is the other end of the hollow fiber membrane bundle, wherein the coefficient of variation of the outer diameter of the plurality of hollow fiber membranes is 3.5 or less.

[0024] In this hollow fiber membrane element, the coefficient of variation of the outer diameter of multiple hollow fiber membranes is 3.5 or less, which reduces liquid pressure loss and stabilizes performance.

[0025]

[16] The hollow fiber membrane module according to the present disclosure comprises a hollow fiber membrane element as described in

[15] and a housing for housing the hollow fiber membrane element, wherein the space within the housing is divided by a plurality of hollow fiber membranes into an internal space including the hollow portion of each of the plurality of hollow fiber membranes and an external space not including the hollow portion of each of the plurality of hollow fiber membranes, and the housing has a gas port communicating with the internal space and a liquid supply port and a liquid discharge port communicating with the external space.

[0026] This hollow fiber membrane module, by incorporating the hollow fiber membrane elements described above, can reduce liquid pressure loss and stabilize performance.

[0027] According to this disclosure, the pressure loss of the liquid can be reduced.

[0028] This is a schematic cross-sectional view of a hollow fiber membrane element according to this embodiment. This is a schematic cross-sectional view along line II-II shown in Figure 1. This is a schematic cross-sectional view showing a part of the hollow fiber membrane element shown in Figure 1. This is a schematic cross-sectional view showing a part of the hollow fiber membrane element shown in Figure 1. This is a perspective view for illustrating an example of the configuration of a hollow fiber membrane bundle. This is a schematic cross-sectional view of a hollow fiber membrane module according to this embodiment. This is a schematic cross-sectional view for illustrating a method for manufacturing a hollow fiber membrane element according to the first second embodiment. This is a schematic cross-sectional view for illustrating a method for manufacturing a hollow fiber membrane element according to the second embodiment. This is a schematic cross-sectional view for illustrating a method for manufacturing a hollow fiber membrane element according to the third embodiment. This is a schematic cross-sectional view of a modified hollow fiber membrane element. This is a schematic cross-sectional view of a modified hollow fiber membrane module equipped with the hollow fiber membrane element shown in Figure 18.

[0029] The manufacturing method of the hollow fiber membrane element, the hollow fiber membrane element, and the hollow fiber membrane module of the embodiment will be described below with reference to the drawings. In all the figures, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0030] [Hollow Fiber Membrane Element] Figure 1 is a schematic cross-sectional view of the hollow fiber membrane element according to this embodiment. Figure 2 is a schematic cross-sectional view taken along line II-II shown in Figure 1. Figure 3 is a schematic cross-sectional view showing a part of the hollow fiber membrane element shown in Figure 1. Figure 4 is a schematic cross-sectional view showing a part of the hollow fiber membrane element shown in Figure 1. As shown in Figures 1 to 4, the hollow fiber membrane element 2 according to this embodiment is for degassing a liquid or adding gas to a liquid, and is used, for example, by being incorporated into a hollow fiber membrane module described later. The liquid is not particularly limited, but examples include water such as seawater, drinking water, pure water, and ultrapure water, aqueous solutions in which ammonium sulfate, surfactants, etc. are dissolved, organic solvents such as alcohol and hydrocarbons, and ionic liquids. The gas to be added to the liquid is not particularly limited, but examples include carbon dioxide (CO2). ２ ), nitrogen (N ２ ) etc. The hollow fiber membrane element 2 comprises a liquid flow pipe 21, a hollow fiber membrane bundle 23, a first fixing part 24, and a second fixing part 25.

[0031] The liquid flow pipe 21 is a cylindrical member that extends in the extension direction D to support the hollow fiber membrane bundle 23. Of the two directions of the extension direction D, one direction is called the first extension direction D1, and the other direction is called the second extension direction D2. In Figure 1, the upper part is the first extension direction D1, and the lower part is the second extension direction D2. The end of the hollow fiber membrane element 2 on the first extension direction D1 side is called the first element end 2a, and the end of the hollow fiber membrane element 2 on the second extension direction D2 side is called the second element end 2b. The liquid flow pipe 21 has sufficient rigidity to support the hollow fiber membrane bundle 23.

[0032] The hollow portion 21a of the liquid flow pipe 21 is a flow path (pipe internal flow path) through which liquid can flow, and is formed by the inner circumferential surface of the liquid flow pipe 21. The liquid flow pipe 21 extends over the entire area in the extending direction D of the hollow fiber membrane element 2. That is, the liquid flow pipe 21 extends from the end of the hollow fiber membrane element 2 in the first extending direction D1 to the end of the hollow fiber membrane element 2 in the second extending direction D2. The hollow portion 21a of the liquid flow pipe 21 is open in the first extending direction D1 and the second extending direction D2. The opening of the hollow portion 21a of the liquid flow pipe 21 at the first element end 2a, that is, the opening of the hollow portion 21a of the liquid flow pipe 21 on the first extending direction D1 side, is called the first end liquid flow pipe opening 21b. The opening of the hollow portion 21a of the liquid flow pipe 21 at the end 2b of the second element, that is, the opening of the hollow portion 21a of the liquid flow pipe 21 on the second extending direction D2 side, is called the second end liquid flow pipe opening 21c.

[0033] The liquid flow pipe 21 has a plurality of openings 21d. These multiple openings 21d are holes for allowing liquid to flow between the hollow portion 21a and the outside of the liquid flow pipe 21, separate from the first end liquid flow pipe opening 21b and the second end liquid flow pipe opening 21c. In other words, the multiple openings 21d are holes for the liquid to pass through the liquid flow pipe 21 in the radial direction. The multiple openings 21d are formed in the peripheral wall of the liquid flow pipe 21, opening the hollow portion 21a to the outside of the liquid flow pipe 21.

[0034] The hollow fiber membrane bundle 23 is formed by bundling multiple hollow fiber membranes 22 in a cylindrical shape. The multiple hollow fiber membranes 22 extend along the liquid flow pipe 21 and are arranged around the liquid flow pipe 21 so as to cover multiple openings 21d. The statement that the multiple hollow fiber membranes 22 extend along the liquid flow pipe 21 means that in the initial state (unused state) of the hollow fiber membrane element 2, the multiple hollow fiber membranes 22 extend along the extension direction D. The multiple hollow fiber membranes 22 are bundled in a cylindrical shape by being arranged around the liquid flow pipe 21. Therefore, the hollow fiber membrane bundle 23 is formed by the multiple hollow fiber membranes 22 into a cylindrical shape that extends along the extension direction D. One end of the hollow fiber membrane bundle 23 is called the first membrane bundle end 23a. The other end of the hollow fiber membrane bundle 23 is called the second membrane bundle end 23b.

[0035] Figure 5 is a perspective view illustrating an example of the configuration of a hollow fiber membrane bundle. As shown in Figure 5, the hollow fiber membrane bundle 23 may be a hollow fiber membrane sheet 26 in which a plurality of hollow fiber membranes 22 are connected in a curtain-like manner by a plurality of connecting threads 27, and which is wound into a cylindrical shape. The hollow fiber membrane sheet 26 is also called a hollow fiber membrane curtain. The curtain-like manner is also called a grid-like manner, etc. The plurality of hollow fiber membranes 22 function as the weft threads of the hollow fiber membrane sheet 26, and the plurality of connecting threads 27 function as the warp threads of the hollow fiber membrane sheet 26. For example, polyethylene terephthalate (PET) or polypropylene (PP) can be used as the connecting threads 27. The plurality of hollow fiber membranes 22 and the plurality of connecting threads 27 can be connected by, for example, knitting, weaving, bonding, welding, etc. The hollow fiber membrane sheet 26 is wound around a liquid flow pipe 21 such that the plurality of hollow fiber membranes 22 extend in the extending direction D and cover a plurality of openings 21d. The hollow fiber membrane sheet 26 is wrapped around the liquid flow pipe 21 by, for example, gripping the liquid flow pipe 21 with a chuck and rotating the liquid flow pipe 21 together with the chuck.

[0036] As shown in Figures 1 to 4, the hollow portion 22a of the hollow fiber membrane 22 is a gas flow path (internal membrane flow path) and is formed by the inner circumferential surface of the hollow fiber membrane 22. The multiple hollow fiber membranes 22 extend over the entire area in the extension direction D of the hollow fiber membrane element 2. That is, the multiple hollow fiber membranes 22 extend from the end of the hollow fiber membrane element 2 in the first extension direction D1 to the end of the hollow fiber membrane element 2 in the second extension direction D2. The hollow portions 22a of the multiple hollow fiber membranes 22 are open in the first extension direction D1 and the second extension direction D2. Note that the hollow portion 22a of the multiple hollow fiber membranes 22 refers to the hollow portion 22a of each of the multiple hollow fiber membranes 22. The opening of the hollow portion 22a of the multiple hollow fiber membranes 22 at the end 2a of the first element, that is, the opening on the first extension direction D1 side of the hollow portion 22a of the multiple hollow fiber membranes 22, is called the first end hollow fiber membrane opening 22b. The opening of the hollow portion 22a of the multiple hollow fiber membranes 22 at the end 2b of the second element, that is, the opening on the second extension direction D2 side of the hollow portion 22a of the multiple hollow fiber membranes 22, is called the second end hollow fiber membrane opening 22c.

[0037] The hollow fiber membrane 22 is a hollow fiber membrane that allows gas to permeate but not liquid. The material, membrane shape, and membrane morphology of the hollow fiber membrane 22 are not particularly limited. Examples of materials for the hollow fiber membrane 22 include polyolefin resins such as polypropylene, polyethylene, and polymethylpentene; silicone resins such as polydimethylsiloxane and its copolymers; and fluorine resins such as PTFE and vinylidene fluoride. Examples of membrane shapes (sidewall shapes) of the hollow fiber membrane 22 include porous membranes, microporous membranes, and homogeneous membranes (non-porous membranes) that do not have porosity. Examples of membrane morphologies of the hollow fiber membrane 22 include symmetrical membranes (homogeneous membranes) in which the chemical or physical structure of the entire membrane is homogeneous, and asymmetrical membranes (heterogeneous membranes) in which the chemical or physical structure of the membrane differs depending on the part of the membrane. An asymmetrical membrane (heterogeneous membrane) is a membrane that has a non-porous dense layer and a porous layer. In this case, the dense layer may be formed anywhere in the membrane, such as on the surface or inside the porous membrane. Heterogeneous membranes also include composite membranes with different chemical structures and multilayer membranes such as three-layer structures. Heterogeneous membranes using poly-4-methylpentene-1 resin are particularly preferred because they have a dense layer that blocks liquids.

[0038] The outer diameter of the hollow fiber membrane 22 is not particularly limited. From the viewpoint of increasing the membrane area, the outer diameter of the hollow fiber membrane 22 can be, for example, 500 μm or less, preferably 350 μm or less, and more preferably 250 μm or less. On the other hand, from the viewpoint of suppressing breakage, the outer diameter of the hollow fiber membrane 22 can be, for example, 50 μm or more, preferably 150 μm or more, and more preferably 200 μm or more.

[0039] As shown in Figures 1 to 3, the first fixing part 24 is made of resin and fixes the first membrane bundle end 23a of the hollow fiber membrane bundle 23. The first fixing part 24 is located at the first element end 2a. The first fixing part 24 fixes the multiple hollow fiber membranes 22 to each other at the first membrane bundle end 23a. The first fixing part 24 also fixes the first membrane bundle end 23a to the liquid flow pipe 21. The first fixing part 24 seals the space between the liquid flow pipe 21 and the hollow fiber membrane bundle 23, and between the multiple hollow fiber membranes 22 in the hollow fiber membrane bundle 23. Furthermore, since the first fixing part 24 is not provided in the hollow portion 21a of the liquid flow pipe 21 and the hollow portion 22a of the multiple hollow fiber membranes 22, the hollow portion 21a of the liquid flow pipe 21 and the hollow portion 22a of the multiple hollow fiber membranes 22 are open. In other words, the first fixing part 24 seals the space between the liquid flow pipe 21 and the hollow fiber membrane bundle 23, and the spaces between the multiple hollow fiber membranes 22 in the hollow fiber membrane bundle 23, while fixing the multiple hollow fiber membranes 22 to the liquid flow pipe 21 at the end of the first membrane bundle 23a so as to open the hollow portion 21a of the liquid flow pipe 21 and the hollow portions 22a of the multiple hollow fiber membranes 22. Examples of the resin material for the first fixing part 24 include thermosetting resins or thermoplastic resins, and may be any one of epoxy resins, urethane resins, and olefin resins.

[0040] More specifically, thermosetting resins can include, for example, epoxy resins, unsaturated polyester resins, polyurethane resins, and silicone resins. Of these, epoxy resins, polyurethane resins, and silicone resins are preferred from the viewpoint of balancing moldability, curing time, adhesion, and hardness, with epoxy resins and polyurethane resins being more preferred, and epoxy resins being even more preferred due to their high heat resistance and chemical resistance. As thermosetting resins, for example, two-component curable resins with the above-mentioned resin as the main component are suitably used, and known curing agents such as aliphatic amines, polyetheramines, aromatic amines, acid anhydrides, and isocyanate compounds can be appropriately selected and contained. Examples of thermoplastic resins include polyethylene, polyolefins such as polypropylene, polyethersulfone, polystyrene, polyphenylene sulfide, polyarylate, polyester, liquid crystal polyester, polyamide, and polymethyl methacrylate. Of these, resins with a melting point of 170°C or lower are preferred from the viewpoint of balancing moldability, curing time, adhesion, and hardness, with polyethylene resins and polypropylene resins being more preferred. In this disclosure, "curing" of a resin means that a thermosetting resin or its initial condensate becomes insoluble and infusible due to crosslinking by heat, a catalyst, etc., and that a thermoplastic resin solidifies upon cooling after being in a state of softening and flowing due to heating.

[0041] The second fixing part 25 is made of resin and fixes the second membrane bundle end portion 23b of the hollow fiber membrane bundle 23. The second fixing part 25 is located at the second element end portion 2b. And at the second membrane bundle end portion 23b, the second fixing part 25 fixes a plurality of hollow fiber membranes 22 to each other. Also, the second fixing part 25 fixes the second membrane bundle end portion 23b to the liquid flow pipe 21. The second fixing part 25 seals between the liquid flow pipe 21 and the hollow fiber membrane bundle 23 and between the plurality of hollow fiber membranes 22 in the hollow fiber membrane bundle 23. Also, the second fixing part 25 is not provided in the hollow portion 21a of the liquid flow pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22, thereby opening the hollow portion 21a of the liquid flow pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22. That is, the second fixing part 25 fixes the plurality of hollow fiber membranes 22 to the liquid flow pipe 21 at the second membrane bundle end portion 23b so as to seal between the liquid flow pipe 21 and the hollow fiber membrane bundle 23 and between the plurality of hollow fiber membranes 22 in the hollow fiber membrane bundle 23 and to open the hollow portion 21a of the liquid flow pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22. The resin used for the second fixing part 25 can be, for example, the same as the resin used for the first fixing part 24.

[0042] Note that the plurality of hollow fiber membranes 22 are not covered by members such as a housing and are exposed outside the hollow fiber membrane element 2 between the first fixing part 24 and the second fixing part 25.

[0043] Here, the outer diameter variation coefficient of the plurality of hollow fiber membranes 22 is referred to as the outer diameter variation coefficient CV. The outer diameter variation coefficient CV is a statistical index indicating the variation in the outer diameters of the plurality of hollow fiber membranes 22. Note that the larger the outer diameter variation coefficient CV, the larger the variation in the outer diameters between the plurality of hollow fiber membranes 22, and the smaller the outer diameter variation coefficient CV, the smaller the variation in the outer diameters between the plurality of hollow fiber membranes 22.

[0044] The outer diameter variation coefficient CV is determined as follows. First, the outer diameter of each of the plurality of hollow fiber membranes 22 is measured. When the outer diameter of the hollow fiber membrane 22 is not constant in the extending direction of the hollow fiber membrane 22, for example, an arbitrary 10-cm portion of the hollow fiber membrane 22 is selected, and the average value of the outer diameter of this selected portion is taken as the outer diameter of the hollow fiber membrane 22. Next, based on the outer diameter of each of the plurality of measured hollow fiber membranes 22, the standard deviation σ of the outer diameters of the plurality of hollow fiber membranes 22 and the average value μ of the outer diameters of the plurality of hollow fiber membranes 22 are calculated. Then, the standard deviation σ of the outer diameters of the plurality of hollow fiber membranes 22 is divided by the average value μ of the outer diameters of the plurality of hollow fiber membranes 22, and the result expressed as a percentage is taken as the outer diameter variation coefficient CV. That is, the outer diameter variation coefficient CV is σ / μ×100.

[0045] In the hollow fiber membrane element 2, the outer diameter variation coefficient CV of the plurality of hollow fiber membranes 22 is 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less.

[0046] [Hollow Fiber Membrane Module] Next, referring to FIG. 6, the hollow fiber membrane module according to the present embodiment will be described. FIG. 6 is a schematic cross-sectional view of the hollow fiber membrane module according to the present embodiment. The hollow fiber membrane module 1 shown in FIG. 6 is a module for degassing a liquid or adding a gas to a liquid. As shown in FIG. 6, the hollow fiber membrane module 1 according to the present embodiment includes the above-described hollow fiber membrane element 2, a housing 3, and a closing portion 4.

[0047] The housing 3 houses the hollow fiber membrane element 2 such that a space is formed between the housing 3 and the plurality of hollow fiber membranes 22. This space is a space through which a liquid can flow between the hollow fiber membrane element 2 and the housing 3.

[0048] The housing 3 comprises a cylindrical portion 31 in which the hollow fiber membrane element 2 is housed, a first lid portion 32 attached to one end of the cylindrical portion 31, and a second lid portion 33 attached to the end of the cylindrical portion 31 opposite to the first lid portion 32. The hollow fiber membrane element 2 is housed in the cylindrical portion 31 such that the extending direction D of the hollow fiber membrane element 2 is the extending direction of the cylindrical portion 31, that is, the opposing direction of the first lid portion 32 and the second lid portion 33. As a result, the extending direction D of the hollow fiber membrane element 2 and the extending direction of the cylindrical portion 31 are in the same direction, and therefore the extending direction of the cylindrical portion 31 is also called the extending direction D.

[0049] The cylindrical portion 31 is airtightly fitted with a first fixing portion 24 and a second fixing portion 25. In other words, the space between the cylindrical portion 31 and the first fixing portion 24 and the space between the cylindrical portion 31 and the second fixing portion 25 are kept airtight. The space inside the housing 3 is divided by the plurality of hollow fiber membranes 22 as boundaries into an internal space S1 which includes the hollow portions 22a of each of the plurality of hollow fiber membranes 22, and an external space S2 which does not include the hollow portions 22a of each of the plurality of hollow fiber membranes 22. The external space S2 includes the hollow portions 21a of the liquid flow pipe 21, the space between the hollow fiber membrane bundle 23 and the liquid flow pipe 21, the space between the plurality of hollow fiber membranes 22 in the hollow fiber membrane bundle 23, and the space between the hollow fiber membrane bundle 23 and the housing 3. The external space S2 is the liquid phase region to which the liquid is supplied. The internal space S1 is the gas phase region through which the gas degassed from the liquid flows. Furthermore, the multiple hollow fiber membranes 22 prevent the permeation of liquid from the external space S2 to the internal space S1, while allowing the permeation of gas from the external space S2 to the internal space S1.

[0050] The first fixing portion 24 and the second fixing portion 25 may be attached to the cylindrical portion 31 in such a way that they can be detachably attached to the cylindrical portion 31. In this case, the first fixing portion 24 and the second fixing portion 25 can be attached to the cylindrical portion 31 by, for example, screwing, fitting, or the like.

[0051] The first lid portion 32 is attached to the end of the cylindrical portion 31 on the first extending direction D1 side so as to cover the opening on the first extending direction D1 side of the cylindrical portion 31. The first lid portion 32 forms a first communication space S3 between itself and the hollow fiber membrane element 2 that communicates with the hollow portions 22a of the multiple hollow fiber membranes 22. The first lid portion 32 may be attached to the cylindrical portion 31 so as to be detachable from the cylindrical portion 31. In this case, the first lid portion 32 can be attached to the cylindrical portion 31 by, for example, screwing, fitting, etc.

[0052] The second cover portion 33 is attached to the end of the cylindrical portion 31 on the second extending direction D2 side so as to cover the opening on the second extending direction D2 side of the cylindrical portion 31. The second cover portion 33 forms a second communication space S4 between itself and the hollow fiber membrane element 2, which communicates with the hollow portions 22a of the multiple hollow fiber membranes 22. The second cover portion 33 may be attached to the cylindrical portion 31 so as to be detachable from the cylindrical portion 31. In this case, the second cover portion 33 can be attached to the cylindrical portion 31 by means of screwing, fitting, etc.

[0053] The housing 3 has a liquid supply port 35 and a liquid discharge port 36 that communicate with the external space S2, and a first gas port 38 and a second gas port 39 that communicate with the internal space S1.

[0054] The liquid supply port 35 is a port for supplying liquid to the hollow portion 21a of the liquid flow pipe 21. The liquid supply port 35 is provided on the second lid portion 33 and connects the inside and outside of the housing 3. The liquid supply port 35 may be integrally formed with the second lid portion 33, or it may be a separate component from the second lid portion 33. The liquid supply port 35 extends in a pipe-like manner from the second lid portion 33 into the inside of the housing 3 and is connected to the end portion 21e of the liquid flow pipe 21 on the second extending direction D2 side. The liquid supply port 35 is in communication with the hollow portion 21a of the liquid flow pipe 21.

[0055] The liquid discharge port 36 is a port for discharging liquid that has come out of the hollow portion 21a of the liquid flow pipe 21. The liquid discharge port 36 is provided on the cylindrical portion 31 and connects the inside and outside of the housing 3. The liquid discharge port 36 may be integrally formed with the cylindrical portion 31, or it may be a separate component from the cylindrical portion 31. For example, the liquid discharge port 36 is provided near the end of the cylindrical portion 31 on the first extending direction D1 side. The liquid discharge port 36 is adjacent to the external space S2 and communicates with the external space S2.

[0056] The first gas port 38 is a port for passing gas degassed from a liquid or gas added to a liquid. The first gas port 38 is provided on the first lid 32 and connects the inside and outside of the housing 3. The first gas port 38 may be integrally formed with the first lid 32, or it may be a separate component from the first lid 32. The first gas port 38 is adjacent to the first communication space S3 and communicates with the first communication space S3.

[0057] The second gas port 39 is a port for passing gas degassed from the liquid or gas added to the liquid. The second gas port 39 is provided on the second lid 33 and connects the inside and outside of the housing 3. The second gas port 39 may be integrally formed with the second lid 33, or it may be a separate component from the second lid 33. The second gas port 39 is adjacent to the second communication space S4 and communicates with the second communication space S4.

[0058] The closure portion 4 blocks the end 21f of the hollow portion 21a of the liquid flow pipe 21 on the first extending direction D1 side. In other words, the closure portion 4 blocks the hollow portion 21a at the end 21f of the liquid flow pipe 21 on the first extending direction D1 side. The closure portion 4 is fitted onto the end 21f of the hollow portion 21a of the liquid flow pipe 21 on the first extending direction D1 side. The closure portion 4 is also called a plug or the like. The closure portion 4 may be formed integrally with the first lid portion 32. The closure portion 4 prevents the liquid supplied to the hollow portion 21a of the liquid flow pipe 21 from being discharged from the liquid flow pipe 21 in the first extending direction D1. Therefore, the liquid is not discharged from the liquid flow pipe 21 in the first extending direction D1, but is discharged radially outward from the liquid flow pipe 21 through a plurality of openings 21d formed in the liquid flow pipe 21.

[0059] Furthermore, the hollow portion 21a of the liquid flow pipe 21 is not provided with any member other than the blocking portion 4 to prevent the liquid from moving in the direction of extension D.

[0060] When degassing a liquid using the hollow fiber membrane module 1, the first gas port 38 and the second gas port 39 are sucked, or sweep gas is supplied to the first gas port 38 or the second gas port 39, while liquid is supplied to the liquid supply port 35. The liquid supplied to the liquid supply port 35 is supplied to the hollow portion 21a of the liquid flow pipe 21 from the second end liquid flow pipe opening 21c (see Figure 1), discharged to the outside of the liquid flow pipe 21 through multiple openings 21d of the liquid flow pipe 21, and comes into contact with the multiple hollow fiber membranes 22. At this time, the hollow portions 22a of the multiple hollow fiber membranes 22 are under reduced pressure due to the sucking of the first gas port 38 and the second gas port 39. Alternatively, sweep gas is supplied to the first gas port 38 or the second gas port 39, causing the sweep gas to flow into the hollow portions 22a of the multiple hollow fiber membranes 22. Therefore, gases such as dissolved gases in the liquid and bubbles contained in the liquid permeate through the multiple hollow fiber membranes 22, and the liquid is degassed. The degassed liquid is discharged from the liquid discharge port 36. The gas that has permeated through the multiple hollow fiber membranes 22 passes through the hollow portions 22a of the multiple hollow fiber membranes 22, the first communication space S3, and the second communication space S4, and is discharged from the first gas port 38 and the second gas port 39, or from the second gas port 39.

[0061] When adding gas to a liquid using the hollow fiber membrane module 1, gas is supplied to the hollow portions 22a of the multiple hollow fiber membranes 22 from the first gas port 38 and the second gas port 39, and liquid is supplied to the liquid supply port 35. The liquid supplied to the liquid supply port 35 is supplied to the hollow portions 21a of the liquid flow pipe 21 from the second end liquid flow pipe opening 21c (see Figure 1), and is discharged to the outside of the liquid flow pipe 21 from the multiple openings 21d of the liquid flow pipe 21, coming into contact with the multiple hollow fiber membranes 22. At this time, the supply of gas to the first gas port 38 and the second gas port 39 pressurizes the hollow portions 22a of the multiple hollow fiber membranes 22. Therefore, the gas supplied to the hollow portions 22a of the multiple hollow fiber membranes 22 from the first gas port 38 and the second gas port 39 permeates the multiple hollow fiber membranes 22, and gas is added to the liquid. The liquid with added gas is discharged from the liquid discharge port 36.

[0062] [Method for Manufacturing a Hollow Fiber Membrane Element According to the First Embodiment] Next, a method for manufacturing a hollow fiber membrane element according to the first embodiment will be described with reference to Figures 7 to 14. Figures 7 to 14 are schematic cross-sectional views illustrating the method for manufacturing a hollow fiber membrane element according to the first embodiment. The method for manufacturing a hollow fiber membrane element according to the first embodiment is a method for manufacturing the above-described hollow fiber membrane element 2, and comprises a membrane bundle formation step, a first fixing step, a second fixing step, and a cutting step.

[0063] In the membrane bundle formation process, as shown in Figure 7, a hollow fiber membrane bundle 123 is formed by bundling multiple hollow fiber membranes 122 in a cylindrical shape so as to cover the periphery of the liquid flow pipe 121. The liquid flow pipe 121 is longer in the extension direction D than the liquid flow pipe 21 of the hollow fiber membrane element 2. The hollow fiber membranes 122 are longer in the extension direction D than the hollow fiber membranes 22 of the hollow fiber membrane element 2. The hollow fiber membrane bundle 123 is longer in the extension direction D than the hollow fiber membrane bundle 23 of the hollow fiber membrane element 2. In the membrane bundle formation process, for example, the hollow fiber membrane bundle 123 may be formed by winding a hollow fiber membrane sheet, in which multiple hollow fiber membranes 122 are connected in a curtain-like manner by multiple connecting threads, around the liquid flow pipe 121.

[0064] The first and second fixing steps are performed after the membrane bundle formation step. In the first fixing step, one end of the hollow fiber membrane bundle 123, the first membrane bundle end 123a, is fixed with resin. In the first fixing step, the resin used to fix the first membrane bundle end 123a is cured while being cooled. In the second fixing step, the other end of the hollow fiber membrane bundle 123, the second membrane bundle end 123b, is fixed with resin. In the second fixing step, the resin used to fix the second membrane bundle end 123b is cured while being cooled. The first and second fixing steps may be performed in any order. In this embodiment, the first fixing step is performed first, followed by the second fixing step.

[0065] In the first fixing step, a cylindrical container 101 is prepared, as shown in Figure 8. The cylindrical container 101 is an open-topped container. The cylindrical container 101 has a cylindrical boss 102 that extends upward from the bottom surface of the cylindrical container 101. The boss 102 is inserted into the liquid flow pipe 121 to seal the hollow portion 121a of the liquid flow pipe 121. Then, in the first fixing step, the first membrane bundle end 123a is inserted into the cylindrical container 101, and the boss 102 is inserted into the liquid flow pipe 121. As a result, the hollow portion 121a of the liquid flow pipe 121 is sealed by the boss 102.

[0066] In the first fixing step, as shown in Figure 9, a resin for fixing the first membrane bundle end 123a is injected into the cylindrical container 101. If the resin injected into the cylindrical container 101 is a thermoplastic resin, it is the molten resin that forms the first fixing portion 24 of the hollow fiber membrane element 2. On the other hand, if the resin injected into the cylindrical container 101 is a thermosetting resin, it is in a fluid state before the formation of an initial condensate, and in the first fixing step, it can be injected, for example, alone or in the presence of a curing agent, or the main component can be injected into the cylindrical container 101 first, and then the curing agent can be injected into the cylindrical container 101.

[0067] In the first fixing step, the resin is cured while the cylindrical container 101 is cooled (forced cooling), as shown in Figure 10. Here, the resin is at a high temperature due to the heating during curing, or it hardens while generating heat, so the heat from this resin causes multiple hollow fiber membranes 122 to shrink around the first membrane bundle end 123a of the hollow fiber membrane bundle 123. If the resin is allowed to cool naturally, there will be variations in the degree of thermal shrinkage among the multiple hollow fiber membranes 122. If the variation in thermal shrinkage among the multiple hollow fiber membranes 122 becomes large, the variation in outer diameter among the multiple hollow fiber membranes 122 will also increase, and the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 122 will increase. Therefore, in the first fixing step, instead of allowing the resin to cool naturally, it is forcibly cooled to reduce the variation in the degree of thermal shrinkage among the multiple hollow fiber membranes 122, thereby reducing the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 122. Then, in the first fixing step, the resin is cured while the cylindrical container 101 is cooled (forced cooling) so that, for example, the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 22 is 3.5 or less, preferably 3.0 or less, and more preferably 2.5.

[0068] Cooling (forced cooling) of the cylindrical container 101 can be performed, for example, by air cooling, which involves blowing air onto the cylindrical container 101, or by water cooling, which involves supplying a cooling liquid such as cooling water to the cylindrical container 101. In the case of air cooling or water cooling, a channel may be formed in the cylindrical container 101 through which a gas such as air or a cooling liquid flows.

[0069] As the resin hardens, it forms a first fixing portion 124 that secures the first membrane bundle end 123a. The first fixing portion 124 is longer in the extending direction than the first fixing portion 24 of the hollow fiber membrane element 2. As a result, the first membrane bundle end 123a is fixed by the first fixing portion 124, which is made of resin. After that, the first membrane bundle end 123a is pulled out of the cylindrical container 101.

[0070] In the second fixing step, first, as shown in Figure 11, the second membrane bundle end 123b is inserted into the cylindrical container 101, and the boss 102 is inserted into the liquid flow pipe 121. As a result, the hollow portion 121a of the liquid flow pipe 121 is sealed by the boss 102.

[0071] In the second fixing step, as shown in Figure 12, a resin for fixing the second membrane bundle end 123b is injected into the cylindrical container 101. If the resin injected into the cylindrical container 101 is a thermoplastic resin, it is the molten resin that forms the second fixing portion 25 of the hollow fiber membrane element 2. On the other hand, if the resin injected into the cylindrical container 101 is a thermosetting resin, it is in a fluid state before the formation of an initial condensate, and in the second fixing step, it can be injected, for example, alone or in the presence of a curing agent, or the main component can be injected into the cylindrical container 101 first, and then the curing agent can be injected into the cylindrical container 101.

[0072] In the second fixing step, the resin is cured while the cylindrical container 101 is cooled (forced cooling), as shown in Figure 13. In the second fixing step, similar to the first fixing step, the resin is forcibly cooled instead of being allowed to cool naturally, thereby reducing the variation in the degree of thermal shrinkage among the multiple hollow fiber membranes 122 and reducing the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 122. Then, in the second fixing step, the resin is cured while the cylindrical container 101 is cooled (forced cooling) so that, for example, the coefficient of variation of the outer diameter of the multiple hollow fiber membranes is 3.5 or less, preferably 3.0 or less, and more preferably 2.5.

[0073] The cooling of the cylindrical container 101 can be carried out in the same manner as in the first fixing step. As the resin hardens, it becomes a second fixing part 125 that fixes the second membrane bundle end 123b. The second fixing part 125 is longer in the extending direction than the second fixing part 25 of the hollow fiber membrane element 2. As a result, the second membrane bundle end 123b is fixed by the second fixing part 125, which is made of resin. After that, the second membrane bundle end 123b is withdrawn from the cylindrical container 101.

[0074] In the cutting process, as shown in Figures 14 and 1, the ends of the first membrane bundle end 123a and the second membrane bundle end 123b are cut. In the first and second fixing processes, the hollow portion 121a of the liquid flow pipe 121 is sealed by the boss 102, so even if resin is injected into the cylindrical container 101, the resin does not enter the hollow portion 121a of the liquid flow pipe 121. However, since both ends of the multiple hollow fiber membranes 122 are open, when resin is injected into the cylindrical container 101, a small amount of resin enters the hollow portions 122a of the multiple hollow fiber membranes 122. Therefore, in the cutting process, the ends of the first membrane bundle end 123a and the second membrane bundle end 123b are cut to remove the portions of the hollow portions 122a of the multiple hollow fiber membranes 122 into which the resin has entered. This produces the hollow fiber membrane element 2 shown in Figure 1.

[0075] [Method for Manufacturing a Hollow Fiber Membrane Element According to the Second Embodiment] Next, a method for manufacturing a hollow fiber membrane element according to the second embodiment will be described with reference to Figures 15 and 16. Figures 15 and 16 are schematic cross-sectional views illustrating the method for manufacturing a hollow fiber membrane element according to the second embodiment. The method for manufacturing a hollow fiber membrane element according to the second embodiment is a method for manufacturing the above-mentioned hollow fiber membrane element 2, similar to the method for manufacturing a hollow fiber membrane element according to the first embodiment, and comprises a membrane bundle formation step, a first fixing step, a second fixing step, and a cutting step.

[0076] In the membrane bundle formation step, a hollow fiber membrane bundle 123 is formed in which a plurality of hollow fiber membranes 122 are bundled together in a cylindrical shape so as to cover the periphery of the liquid flow pipe 121, similar to the method for manufacturing the hollow fiber membrane element according to the first embodiment (see Figure 7).

[0077] The first and second fixing steps are performed after the membrane bundle formation step. In the first fixing step, one end of the hollow fiber membrane bundle 123, the first membrane bundle end 123a, is fixed with resin. In the first fixing step, the resin used to fix the first membrane bundle end 123a is cured while being cooled. In the second fixing step, the other end of the hollow fiber membrane bundle 123, the second membrane bundle end 123b, is fixed with resin. In the second fixing step, the resin used to fix the second membrane bundle end 123b is cured while being cooled. The first and second fixing steps may be performed simultaneously, or one may be performed first. In this embodiment, the first and second fixing steps are performed simultaneously.

[0078] In the first and second fixing steps, first, a first cylindrical container 201 and a second cylindrical container 202 are prepared, as shown in Figure 15. The first cylindrical container 201 and the second cylindrical container 202 are containers with one end open. The first cylindrical container 201 and the second cylindrical container 202 may be configured to be detachable from each other. The first cylindrical container 201 has a cylindrical boss 203 that extends upward from the bottom surface of the first cylindrical container 201. The second cylindrical container 202 has a cylindrical boss 204 that extends upward from the bottom surface of the second cylindrical container 202. The bosses 203 and 204 are inserted into the liquid flow pipe 121 to seal the hollow portion 121a of the liquid flow pipe 121. Then, the first membrane bundle end 123a is inserted into the first cylindrical container 201 and the boss 203 is inserted into the liquid flow pipe 121. Furthermore, the second membrane bundle end 123b is inserted into the second cylindrical container 202, and the boss 204 is inserted into the liquid flow pipe 121. As a result, the hollow portion 121a of the liquid flow pipe 121 is sealed by the boss 203 and the boss 204.

[0079] In the first and second fixing steps, the first cylindrical container 201, the second cylindrical container 202, and the hollow fiber membrane bundle 123 are rotated with the central portion 123c in the longitudinal direction of the hollow fiber membrane bundle 123 as axis A, while resin is supplied between the first membrane bundle end 123a and the central portion 123c of the hollow fiber membrane bundle 123, and between the second membrane bundle end 123b and the central portion 123c of the hollow fiber membrane bundle 123. The resin may be supplied near the first membrane bundle end 123a within the space between the first membrane bundle end 123a and the central portion 123c. Alternatively, the resin may be supplied near the second membrane bundle end 123b within the space between the second membrane bundle end 123b and the central portion 123c. The resin supplied to the hollow fiber membrane bundle 123 can be the same as the resin injected into the cylindrical container 101 in the method for manufacturing the hollow fiber membrane element according to the first embodiment.

[0080] The supply of resin between the first membrane bundle end 123a and the central portion 123c, and between the second membrane bundle end 123b and the central portion 123c, can be carried out, for example, by a resin supply device 208 comprising a storage section 205 for storing resin, a first flow path 206 from the storage section 205 to the space between the first membrane bundle end 123a and the central portion 123c of the hollow fiber membrane bundle 123, and a second flow path 207 from the storage section 205 to the space between the second membrane bundle end 123b and the central portion 123c of the hollow fiber membrane bundle 123. That is, the resin supply device 208 is positioned above the hollow fiber membrane bundle 123, and resin is injected into the storage section 205. As a result, the resin stored in the storage section 205 flows down through the first channel 206 and the second channel 207, and is supplied between the first membrane bundle end 123a and the central part 123c of the hollow fiber membrane bundle 123, and between the second membrane bundle end 123b and the central part 123c of the hollow fiber membrane bundle 123.

[0081] The resin supplied between the first membrane bundle end 123a and the central part 123c of the hollow fiber membrane bundle 123 moves to the first membrane bundle end 123a due to the centrifugal force of the rotating hollow fiber membrane bundle 123. Then, the resin remains at the first membrane bundle end 123a because its centrifugal movement is restricted by the first cylindrical container 201. Similarly, the resin supplied between the second membrane bundle end 123b and the central part 123c of the hollow fiber membrane bundle 123 moves to the second membrane bundle end 123b due to the centrifugal force of the rotating hollow fiber membrane bundle 123. Then, the resin remains at the second membrane bundle end 123b because its centrifugal movement is restricted by the second cylindrical container 202.

[0082] In the first fixing step, the resin is cured while the first cylindrical container 201 and the second cylindrical container 202 are cooled (forced cooling), as shown in Figure 16. At this time, the rotation of the first cylindrical container 201, the second cylindrical container 202, and the hollow fiber membrane bundle 123 is continued with the central part 123c in the longitudinal direction of the hollow fiber membrane bundle 123 as axis A, until the resin has hardened to a certain extent. Then, in the first and second fixing steps, the resin is cured while the first cylindrical container 201 and the second cylindrical container 202 are cooled (forced cooling) so that, for example, the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 22 is 3.5 or less, preferably 3.0 or less, and more preferably 2.5.

[0083] Cooling (forced cooling) of the first cylindrical container 201 and the second cylindrical container 202 can be performed, for example, by air cooling, which involves blowing air onto the first cylindrical container 201 and the second cylindrical container 202, or by water cooling, which involves supplying a cooling liquid such as cooling water to the first cylindrical container 201 and the second cylindrical container 202. Air cooling can be performed, for example, by supplying cold air into the case 209 that houses the first cylindrical container 201, the second cylindrical container 202, and the hollow fiber membrane bundle 123, or by blowing air onto the first cylindrical container 201 and the second cylindrical container 202. Furthermore, if the first cylindrical container 201, the second cylindrical container 202, and the hollow fiber membrane bundle 123 are rotated with the central part 123c in the longitudinal direction of the hollow fiber membrane bundle 123 as axis A, air will blow onto the first cylindrical container 201 and the second cylindrical container 202. Therefore, air cooling may be performed by blowing air onto the first cylindrical container 201 and the second cylindrical container 202 by rotating the first cylindrical container 201, the second cylindrical container 202, and the hollow fiber membrane bundle 123.

[0084] As the resin hardens, it becomes a first fixing part 124 that fixes the first membrane bundle end 123a and a second fixing part 125 that fixes the second membrane bundle end 123b. As a result, the first membrane bundle end 123a is fixed by the first fixing part 124, which is made of resin, and the second membrane bundle end 123b is fixed by the second fixing part 125, which is made of resin. After that, the first membrane bundle end 123a is pulled out of the first cylindrical container 201 and the second membrane bundle end 123b is pulled out of the second cylindrical container 202.

[0085] In the cutting process, the ends of the first membrane bundle end 123a and the second membrane bundle end 123b are cut, similar to the method for manufacturing the hollow fiber membrane element according to the first embodiment (see Figure 14). This produces the hollow fiber membrane element 2 shown in Figure 1.

[0086] [Method for Manufacturing a Hollow Fiber Membrane Element According to the Third Embodiment] Next, a method for manufacturing a hollow fiber membrane element according to the third embodiment will be described with reference to Figure 17. Figure 17 is a schematic cross-sectional view illustrating the method for manufacturing a hollow fiber membrane element according to the third embodiment. The method for manufacturing a hollow fiber membrane element according to the third embodiment is a method for manufacturing the above-mentioned hollow fiber membrane element 2, similar to the method for manufacturing a hollow fiber membrane element according to the first embodiment, and comprises a membrane bundle formation step, a first fixing step, a second fixing step, and a cutting step. In the method for manufacturing a hollow fiber membrane element according to the third embodiment, the membrane bundle formation step, the first fixing step, and the second fixing step are performed simultaneously.

[0087] In the membrane bundle formation process, the first fixing process, and the second fixing process, as shown in Figure 17, a hollow fiber membrane sheet 126 is prepared in which multiple hollow fiber membranes 22 are connected in a curtain-like manner by multiple connecting threads 27. Then, a hollow fiber membrane bundle 123 is formed by winding the hollow fiber membrane sheet 126 into a cylindrical shape while applying resin to the surface 126a of the hollow fiber membrane sheet 126. The hollow fiber membrane sheet 126 is longer in the width direction (the direction in which the hollow fiber membranes 22 extend) than the hollow fiber membrane sheet 26 of the hollow fiber membrane element 2. Specifically, resin is applied to the surface 126a of the hollow fiber membrane sheet 126 at a position corresponding to the first membrane bundle end 123a, which is one end of the hollow fiber membrane bundle 123, and at a position corresponding to the second membrane bundle end 123b, which is the other end of the hollow fiber membrane bundle 123. The resin applied to the hollow fiber membrane sheet 126 can be the same as the resin injected into the cylindrical container 101 in the manufacturing method of the hollow fiber membrane element according to the first embodiment. Then, the hollow fiber membrane sheet 126 coated with these resins is wound around the liquid flow pipe 121. This forms a hollow fiber membrane bundle 123 with resin attached to the first membrane bundle end 123a and the second membrane bundle end 123b.

[0088] Next, the resin is cured while cooling (forced cooling) the first membrane bundle end 123a and the second membrane bundle end 123b. At this time, for example, the resin is cured while cooling (forced cooling) the first membrane bundle end 123a and the second membrane bundle end 123b so that the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 22 is 3.5 or less, preferably 3.0 or less, and more preferably 2.5.

[0089] Cooling (forced cooling) of the first membrane bundle end 123a and the second membrane bundle end 123b can be performed, for example, by air cooling, which involves blowing air onto the first membrane bundle end 123a and the second membrane bundle end 123b. Air cooling can be performed, for example, by blowing air onto the first membrane bundle end 123a and the second membrane bundle end 123b, or by moving the hollow fiber membrane bundle 123 to blow air onto the first membrane bundle end 123a and the second membrane bundle end 123b.

[0090] In the cutting process, the ends of the first membrane bundle end 123a and the second membrane bundle end 123b are cut, similar to the method for manufacturing the hollow fiber membrane element according to the first embodiment (see Figure 14). This produces the hollow fiber membrane element 2 shown in Figure 1.

[0091] As described above, in the manufacturing method of the hollow fiber membrane element according to each embodiment, in the first fixing step, the resin that fixes the first membrane bundle end 123a is hardened while cooling the resin, thereby fixing the first membrane bundle end 123a with the resin. As a result, the total amount of heat generated when the resin hardens is reduced, so the degree of thermal contraction of the hollow fiber membrane bundle 123 due to the heat of the resin is reduced, the variation in the degree of thermal contraction among the multiple hollow fiber membranes 122 is reduced, and the variation in outer diameter among the multiple hollow fiber membranes 122 is reduced. Therefore, the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 22 in the manufactured hollow fiber membrane element 2 is reduced. As a result, when liquid is flowed between the multiple hollow fiber membranes 22, the uneven flow of the liquid flowing between the multiple hollow fiber membranes 22 is mitigated, and the pressure loss of the liquid as it passes between the multiple hollow fiber membranes 22 can be reduced.

[0092] Furthermore, in the method for manufacturing the hollow fiber membrane element according to the first embodiment, in the first fixing step, the first membrane bundle end 123a is inserted into the cylindrical container 101, resin is injected into the cylindrical container 101, and the resin is cured while the cylindrical container 101 is cooled. This makes it possible to fix the first membrane bundle end 123a with the resin while the resin is being cured and cooled.

[0093] Furthermore, in the method for manufacturing a hollow fiber membrane element according to the second embodiment, in the first fixing step, the first membrane bundle end 123a is inserted into the first cylindrical container 201, and the first cylindrical container 201 and the hollow fiber membrane bundle 123 are rotated with the central portion 123c in the longitudinal direction of the hollow fiber membrane bundle 123 as axis A, while resin is supplied between the first membrane bundle end 123a and the central portion 123c of the hollow fiber membrane bundle 123, and the resin is cured while the first cylindrical container 201 is cooled. This makes it possible to cure the resin while cooling it when fixing the first membrane bundle end 123a with the resin.

[0094] Furthermore, in the manufacturing methods for hollow fiber membrane elements according to the first and second embodiments, the cylindrical container 101 or the first cylindrical container 201 can be cooled by air cooling, which involves blowing air onto the cylindrical container 101 or the first cylindrical container 201. Therefore, the cylindrical container 101 or the first cylindrical container 201 can be cooled by simple means.

[0095] Furthermore, in the manufacturing method of the hollow fiber membrane element according to the first and second embodiments, the cylindrical container 101 or the first cylindrical container 201 can be cooled by water cooling, which involves supplying a cooling liquid to the cylindrical container 101 or the first cylindrical container 201. Therefore, the cylindrical container 101 or the first cylindrical container 201 can be cooled efficiently.

[0096] Furthermore, in the manufacturing method of the hollow fiber membrane element according to the third embodiment, in the membrane bundle formation step, a hollow fiber membrane bundle 123 is formed by applying resin to the surface 126a of the hollow fiber membrane sheet 126, in which a plurality of hollow fiber membranes 22 are connected in a curtain-like manner by a plurality of connecting threads 27, while winding the hollow fiber membrane sheet 126 into a cylindrical shape. This makes it possible to easily form a hollow fiber membrane bundle 123 in which a plurality of hollow fiber membranes 22 are bundled into a cylindrical shape.

[0097] Furthermore, in the manufacturing method of the hollow fiber membrane element according to the third embodiment, in the first fixing step, the first membrane bundle end 123a is cooled by air cooling by blowing air onto the first membrane bundle end 123a. This allows the resin that fixes the first membrane bundle end 123a to be cooled and cured, thereby fixing the first membrane bundle end 123a with the resin.

[0098] Furthermore, in the manufacturing method of the hollow fiber membrane element according to each embodiment, the material of the plurality of hollow fiber membranes 122 is polyolefin resin, and the resin used to fix the first membrane bundle end 123a and the second membrane bundle end 123b is one of epoxy resin, urethane resin, and olefin resin, so that the first membrane bundle end 123a and the second membrane bundle end 123b can be properly fixed.

[0099] Furthermore, in the manufacturing method of the hollow fiber membrane element according to each embodiment, if the resin used to fix the first membrane bundle end is a thermosetting resin, a curing agent that accelerates the curing of the resin can be injected into the cylindrical container 101 along with the resin in the first and second fixing steps. As a result, the first membrane bundle end 123a and the second membrane bundle end 123b harden more quickly, further reducing the total amount of heat generated when the resin hardens. This further reduces the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 22 in the manufactured hollow fiber membrane element 2.

[0100] Furthermore, in the manufacturing method of the hollow fiber membrane element according to each embodiment, in the first fixing step, the resin that fixes the ends of the first membrane bundle is cured while being cooled so that the coefficient of variation of the outer diameter of the plurality of hollow fiber membranes 122 is 3.5 or less, preferably 3.0 or less, and more preferably 2.5 or less. As a result, the liquid pressure loss in the manufactured hollow fiber membrane element 2 can be reduced and the performance can be stabilized.

[0101] Furthermore, in the manufacturing method of the hollow fiber membrane element according to the first embodiment, in the second fixing step, the resin that fixes the second membrane bundle end 123b is fixed with the resin by curing the resin while cooling it. As a result, the total amount of heat generated when the resin hardens is reduced, which reduces the degree of thermal contraction of the hollow fiber membrane bundle 123 due to the heat of the resin, reduces the variation in the degree of thermal contraction among the multiple hollow fiber membranes 122, and further reduces the variation in outer diameter among the multiple hollow fiber membranes 122. Therefore, the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 22 in the manufactured hollow fiber membrane element 2 becomes even smaller. As a result, when liquid is flowed between the multiple hollow fiber membranes 22, the uneven flow of the liquid flowing between the multiple hollow fiber membranes 22 is further reduced, and the pressure loss of the liquid as it passes between the multiple hollow fiber membranes 22 can be further reduced.

[0102] Furthermore, in the method for manufacturing the hollow fiber membrane element according to the first embodiment, in the second fixing step, the second membrane bundle end 123b is inserted into the cylindrical container 101, resin is injected into the cylindrical container 101, and the resin is cured while the cylindrical container 101 is cooled. This makes it possible to fix the second membrane bundle end 123b with the resin while the resin is being cured and cooled.

[0103] Furthermore, in the method for manufacturing a hollow fiber membrane element according to the second embodiment, in the second fixing step, the second membrane bundle end 123b is inserted into the second cylindrical container 202, and resin is supplied between the second membrane bundle end 123b and the central part 123c of the hollow fiber membrane bundle 123 and the central part 123c while rotating the second cylindrical container 202 and the hollow fiber membrane bundle 123 with the central part 123c in the longitudinal direction of the hollow fiber membrane bundle 123 as axis A, and the resin is cured while the second cylindrical container 202 is cooled. This makes it possible to cure the resin while cooling it when fixing the second membrane bundle end 123b with the resin.

[0104] Furthermore, in the manufacturing method of the hollow fiber membrane element according to each embodiment, the ends of the first membrane bundle end 123a and the ends of the second membrane bundle end 123b are cut after the first and second fixing steps. Therefore, even if a small amount of resin enters the hollow portion 122a of the multiple hollow fiber membranes 122 during the first and second fixing steps, the hollow portion 122a of the multiple hollow fiber membranes 122 can be opened.

[0105] In the hollow fiber membrane element 2 according to this embodiment, the coefficient of variation of the outer diameter of the multiple hollow fiber membranes 22 is 3.5 or less, preferably 3.0 or less, and more preferably 2.5 or less. Therefore, the pressure loss of the liquid can be reduced and the performance can be stabilized.

[0106] In the hollow fiber membrane module 1 according to this embodiment, since it is equipped with the hollow fiber membrane element 2 described above, the pressure loss of the liquid can be reduced and the performance can be stabilized.

[0107] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above.

[0108] For example, the hollow fiber membrane element may have a baffle between the first fixed portion and the second fixed portion in the extending direction that closes the hollow portion 21a of the liquid flow pipe 21, and further, an intermembrane baffle may be provided that closes the space between the multiple hollow fiber membranes.

[0109] Figure 18 is a schematic cross-sectional view of a modified hollow fiber membrane element. The modified hollow fiber membrane element 2A shown in Figure 18 is basically the same as the hollow fiber membrane element 2 of the above embodiment, but differs from the hollow fiber membrane element 2 of the above embodiment in that it is equipped with a baffle 28 and an intermembrane baffle 29.

[0110] As shown in Figure 18, the baffle 28 prevents the flow of liquid in the direction of extension D in the hollow portion 21a of the liquid flow pipe 21. The baffle 28 blocks the hollow portion 21a of the liquid flow pipe 21 between the first fixed portion 24 and the second fixed portion 25 in the direction of extension D.

[0111] The intermembrane baffle 29 prevents the flow of liquid in the extension direction D in the space between the multiple hollow fiber membranes 22. The intermembrane baffle 29 blocks the space between the multiple hollow fiber membranes 22 at a position corresponding to the baffle 28 between the first fixing part 24 and the second fixing part 25 in the extension direction D. The intermembrane baffle 29 may block all of the space between the multiple hollow fiber membranes 22, or it may block only a portion of the space between the multiple hollow fiber membranes 22.

[0112] Figure 19 is a schematic cross-sectional view of a modified hollow fiber membrane module equipped with the hollow fiber membrane element shown in Figure 18. The modified hollow fiber membrane module 1A shown in Figure 19 is basically the same as the hollow fiber membrane module 1 of the above embodiment, but differs from the hollow fiber membrane module 1 of the above embodiment in that it is equipped with a modified hollow fiber membrane element 2A instead of the hollow fiber membrane element 2.

[0113] As shown in Figure 19, the modified hollow fiber membrane module 1A comprises a modified hollow fiber membrane element 2A and a housing 3A.

[0114] The housing 3A includes a cylindrical portion 31A in which the hollow fiber membrane element 2A is housed, a first lid portion 32A attached to one end of the cylindrical portion 31A, and a second lid portion 33 attached to the end of the cylindrical portion 31A opposite to the first lid portion 32A.

[0115] The cylindrical portion 31A is basically the same as the cylindrical portion 31 of the hollow fiber membrane module 1, but differs from the cylindrical portion 31 of the hollow fiber membrane module 1 in that it does not have a liquid discharge port 36.

[0116] The first lid portion 32A is basically the same as the first lid portion 32 of the hollow fiber membrane module 1, but differs from the first lid portion 32 of the hollow fiber membrane module 1 in that it is provided with a liquid discharge port 36.

[0117] The liquid discharge port 36 is provided in the first lid portion 32A and is a port that connects the inside and outside of the housing 3A. The liquid discharge port 36 extends in a pipe-like manner from the first lid portion 32A to the inside of the housing 3A and is connected to the end portion 21f of the liquid flow pipe 21 on the first extending direction D1 side. The liquid discharge port 36 is in communication with the hollow portion 21a of the liquid flow pipe 21.

[0118] When degassing a liquid using the modified hollow fiber membrane module 1A, the first gas port 38 and the second gas port 39 are sucked, or sweep gas is supplied to the first gas port 38 or the second gas port 39, and liquid is supplied to the liquid supply port 35. The liquid supplied to the liquid supply port 35 exits the liquid flow pipe 21 from multiple openings 21d on the upstream side of the baffle 28 (second end liquid flow pipe opening 21c side), passes through the multiple hollow fiber membranes 22 while in contact with them, passes through the gap between the intermembrane baffle 29 and the cylindrical portion 31A, passes through the multiple hollow fiber membranes 22 again while in contact with them, and returns to the hollow portion 21a of the liquid flow pipe 21 from multiple openings 21d on the downstream side of the baffle 28 (first end liquid flow pipe opening 21b side). At this time, the hollow portion 22a of the multiple hollow fiber membranes 22 is under reduced pressure due to the sucking of the first gas port 38 and the second gas port 39. Alternatively, sweep gas is supplied to the first gas port 38 or the second gas port 39, causing the sweep gas to flow through the hollow portions 22a of the multiple hollow fiber membranes 22. As a result, gases such as dissolved gases in the liquid and bubbles contained in the liquid permeate through the multiple hollow fiber membranes 22, and the liquid is degassed. The degassed liquid is discharged from the liquid discharge port 36. The gas that has permeated through the multiple hollow fiber membranes 22 passes through the hollow portions 22a of the multiple hollow fiber membranes 22, the first communication space S3, and the second communication space S4, and is discharged from the first gas port 38 and the second gas port 39.

[0119] When gas is added to a liquid using the modified hollow fiber membrane module 1A, gas is supplied to the hollow portions 22a of the multiple hollow fiber membranes 22 from the first gas port 38 and the second gas port 39, and liquid is supplied to the liquid supply port 35. The liquid supplied to the liquid supply port 35 exits the liquid flow pipe 21 from the multiple openings 21d on the upstream side of the baffle 28 (second end liquid flow pipe opening 21c side), passes through the multiple hollow fiber membranes 22 while contacting them, passes through the gap between the intermembrane baffle 29 and the cylindrical portion 31A, passes through the multiple hollow fiber membranes 22 again while contacting them, and returns to the hollow portions 21a of the liquid flow pipe 21 from the multiple openings 21d on the downstream side of the baffle 28 (first end liquid flow pipe opening 21b side). At this time, the hollow portions 22a of the multiple hollow fiber membranes 22 are pressurized due to the supply of gas to the first gas port 38 and the second gas port 39. Therefore, the gas supplied to the hollow portions 22a of the multiple hollow fiber membranes 22 from the first gas port 38 and the second gas port 39 permeates through the multiple hollow fiber membranes 22, and the gas is added to the liquid. The liquid to which the gas has been added is discharged from the liquid discharge port 36.

[0120] 1...Hollow fiber membrane module, 1A...Hollow fiber membrane module, 2...Hollow fiber membrane element, 2A...Hollow fiber membrane element, 2a...First element end, 2b...Second element end, 3...Housing, 3A...Housing, 4...Closed section, 21...Liquid flow pipe, 21a...Hollow section, 21b...First end liquid flow pipe opening, 21c...Second end liquid flow pipe opening, 21d...Opening, 21e...End, 21 f...end, 22...hollow fiber membrane, 22a...hollow section, 22b...first end hollow fiber membrane opening, 22c...second end hollow fiber membrane opening, 23...hollow fiber membrane bundle, 23a...first membrane bundle end, 23b...second membrane bundle end, 24...first fixing section, 25...second fixing section, 26...hollow fiber membrane sheet, 27...connecting thread, 28...baffle, 29...intermembrane baffle, 31...cylindrical section, 31A...cylindrical section, 32...first lid section, 32A...first lid section, 33 ...Second lid, 35...Liquid supply port, 36...Liquid discharge port, 38...First gas port, 39...Second gas port, 101...Cylindrical container, 102...Boss, 121...Liquid flow pipe, 121a...Hollow section, 122...Hollow fiber membrane, 122a...Hollow section, 123...Hollow fiber membrane bundle, 123a...First membrane bundle end, 123b...Second membrane bundle end, 123c...Central section, 124...First fixing section, 125...Second fixing section, 126...Hollow fiber membrane sheet, 126a...Surface, 201...First cylindrical container, 202...Second cylindrical container, 203...Boss, 204...Boss, 205...Storage part, 206...First flow path, 207...Second flow path, 20 8... Resin supply device, 209... Case, A... Axis, D... Extending direction, D1... First extending direction, D2... Second extending direction, S1... Internal space, S2... External space, S3... First communicating space, S4... Second communicating space.

Claims

1. A method for manufacturing a hollow fiber membrane element, comprising: a membrane bundle forming step of forming a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled together in a cylindrical shape; a first fixing step of fixing one end of the hollow fiber membrane bundle, which is a first membrane bundle end, with resin; and a second fixing step of fixing the other end of the hollow fiber membrane bundle, which is a second membrane bundle end, with resin, wherein in the first fixing step, the resin used to fix the first membrane bundle end is cured while being cooled.

2. The method for manufacturing a hollow fiber membrane element according to claim 1, wherein in the first fixing step, the end of the first membrane bundle is inserted into a cylindrical container, resin is injected into the cylindrical container, and the resin is cured while the cylindrical container is cooled.

3. The method for manufacturing a hollow fiber membrane element according to claim 1, wherein in the first fixing step, the end of the first membrane bundle is inserted into a first cylindrical container, the first cylindrical container and the hollow fiber membrane bundle are rotated with the central part of the hollow fiber membrane bundle in the longitudinal direction as the axis, the resin is supplied between the end of the first membrane bundle and the central part of the hollow fiber membrane bundle, and the resin is cured while the first cylindrical container is cooled.

4. The method for manufacturing a hollow fiber membrane element according to claim 2 or 3, wherein in the first fixing step, the cylindrical container is cooled by air cooling by blowing air onto the cylindrical container.

5. The method for manufacturing a hollow fiber membrane element according to claim 2 or 3, wherein in the first fixing step, the cylindrical container is cooled by water cooling by supplying a cooling liquid to the cylindrical container.

6. The method for manufacturing a hollow fiber membrane element according to claim 1, wherein in the membrane bundle formation step, the hollow fiber membrane bundle is formed by applying the resin to the surface of a hollow fiber membrane sheet in which the plurality of hollow fiber membranes are connected in a curtain-like manner by a plurality of connecting threads, and winding the hollow fiber membrane sheet into a cylindrical shape.

7. The method for manufacturing a hollow fiber membrane element according to claim 6, wherein in the first fixing step, the end of the first membrane bundle is cooled by air cooling by blowing air onto the end of the first membrane bundle.

8. The method for manufacturing a hollow fiber membrane element according to claim 1, wherein the material of the plurality of hollow fiber membranes is a polyolefin resin, and the resin used to fix the end of the first membrane bundle is one of epoxy resin, urethane resin, and olefin resin.

9. The method for manufacturing a hollow fiber membrane element according to claim 2 or 3, wherein the resin used to fix the end of the first membrane bundle is a thermosetting resin, and in the first fixing step, a curing agent that promotes the curing of the resin is injected into the cylindrical container together with the resin.

10. The method for manufacturing a hollow fiber membrane element according to claim 1, wherein in the first fixing step, the resin used to fix the ends of the first membrane bundle is cured while being cooled so that the coefficient of variation of the outer diameter of the plurality of hollow fiber membranes is 3.5 or less.

11. The method for manufacturing a hollow fiber membrane element according to claim 1, wherein in the second fixing step, the resin used to fix the end of the second membrane bundle is cooled while the resin is cured.

12. The method for manufacturing a hollow fiber membrane element according to claim 2, wherein in the second fixing step, the end of the second membrane bundle is inserted into the cylindrical container, the resin is injected into the cylindrical container, and the resin is cured while the cylindrical container is cooled.

13. The method for manufacturing a hollow fiber membrane element according to claim 3, wherein in the second fixing step, the end of the second membrane bundle is inserted into a second cylindrical container, the second cylindrical container and the hollow fiber membrane bundle are rotated with the central part of the hollow fiber membrane bundle in the longitudinal direction as the axis, the resin is supplied between the end of the second membrane bundle and the central part of the hollow fiber membrane bundle, and the resin is cured while the second cylindrical container is cooled.

14. A method for manufacturing a hollow fiber membrane element according to claim 1, further comprising a cutting step of cutting the ends of the first membrane bundle end and the ends of the second membrane bundle end after the first fixing step and the second fixing step.

15. A hollow fiber membrane element comprising: a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled together in a cylindrical shape; a first fixing part made of resin for fixing a first membrane bundle end, which is one end of the hollow fiber membrane bundle; and a second fixing part made of resin for fixing a second membrane bundle end, which is the other end of the hollow fiber membrane bundle, wherein the coefficient of variation of the outer diameter of the plurality of hollow fiber membranes is 3.5 or less.

16. A hollow fiber membrane module comprising: a hollow fiber membrane element according to claim 15; and a housing for housing the hollow fiber membrane element, wherein the space within the housing is divided by the plurality of hollow fiber membranes into an internal space including the hollow portion of each of the plurality of hollow fiber membranes and an external space not including the hollow portion of each of the plurality of hollow fiber membranes, and the housing has a gas port communicating with the internal space and a liquid supply port and a liquid discharge port communicating with the external space.

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