Hollow fiber membrane element, hollow fiber membrane module, degassing method, and gas addition method

Abstract

This hollow fiber membrane element comprises: a liquid flow pipe in which a plurality of openings are formed; a plurality of hollow fiber membranes disposed around the liquid flow pipe so as to cover the plurality of openings; a first fixing part and a second fixing part that fix the plurality of hollow fiber membranes to the liquid flow pipe; a baffle that obstructs a hollow portion of the liquid flow pipe in an element-intermediate portion; and a space formation member that is disposed between the liquid flow pipe and the plurality of hollow fiber membranes, and in which a plurality of through holes are formed. Between the liquid flow pipe and the space formation member, the space formation member forms linking space for linking the plurality of through holes and at least one opening, among the plurality of openings, positioned between the baffle and the first fixing part in the extending direction.

Description

Hollow fiber membrane element, hollow fiber membrane module, degassing method, and gas addition method

[0001] The present disclosure relates to a hollow fiber membrane element, a hollow fiber membrane module, a degassing method, and a gas addition method.

[0002] Patent Document 1 describes a hollow fiber membrane module with a baffle flow structure for degassing a liquid. This hollow fiber membrane module includes a central tube in which a first perforated tube section and a second perforated tube section are connected via a solid tube connector, a membrane mat (hollow fibers) wound around the central tube, and a casing that houses these. In this hollow fiber membrane module, liquid supplied to the first perforated tube section exits through the holes in the first perforated tube section, passes through the membrane mat wound around the first perforated tube section, the gap between the membrane mat and the casing, and the membrane mat wound around the second perforated tube section, and enters the holes in the second perforated tube section. The liquid is then discharged from the hollow fiber membrane module.

[0003] Patent No. 6002719

[0004] In the hollow fiber membrane module described in Patent Document 1, when the liquid enters the holes of the second perforated tube section, it tries to push the membrane mat wrapped around the second perforated tube section into the holes of the second perforated tube section, causing part of the membrane mat to enter the holes of the second perforated tube section, increasing the pressure loss of the liquid when passing through the holes of the second perforated tube section.

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

[0006] [1] A hollow fiber membrane element according to the present disclosure comprises a liquid distribution pipe having a plurality of openings formed therein, a plurality of hollow fiber membranes extending along the liquid distribution pipe and arranged around the liquid distribution pipe so as to cover the plurality of openings, a first fixing part located at one end of the liquid distribution pipe in the extending direction, which fixes the plurality of hollow fiber membranes to the liquid distribution pipe so as to seal the gap between the liquid distribution pipe and the plurality of hollow fiber membranes and leave hollow portions of the liquid distribution pipe and the plurality of hollow fiber membranes open, and a second fixing part located at the other end of the liquid distribution pipe in the extending direction, which seals the gap between the liquid distribution pipe and the plurality of hollow fiber membranes and leaves hollow portions of the liquid distribution pipe and the plurality of hollow fiber membranes open. a second fixing portion that fixes the plurality of hollow fiber membranes to the liquid flow pipe so as to open the hollow portion of the liquid flow pipe and the hollow portions of the plurality of hollow fiber membranes; a baffle that blocks the hollow portion of the liquid flow pipe in an intermediate portion of the element between the first fixing portion and the second fixing portion in the extension direction; and a space forming member that is disposed between the liquid flow pipe and the plurality of hollow fiber membranes and has a plurality of through holes formed therein, and the space forming member forms a communication space between the liquid flow pipe and at least one opening of the plurality of openings that is located between the baffle and the first fixing portion in the extension direction and the plurality of through holes.

[0007] In this hollow fiber membrane element, the hollow portion of the liquid distribution pipe is blocked by a baffle at an intermediate portion of the element between the first and second fixing portions in the extension direction. Therefore, in a hollow fiber membrane module in which this hollow fiber membrane element is housed in a housing, when liquid is supplied to the hollow portion of the liquid distribution pipe from one side of the liquid distribution pipe, the liquid exits the liquid distribution pipe through an opening on the upstream side of the baffle, comes into contact with the multiple hollow fiber membranes, returns to the hollow portion of the liquid distribution pipe through an opening on the downstream side of the baffle, and is discharged from the other side of the liquid distribution pipe.

[0008] Here, when the liquid returns from the openings to the hollow portion of the liquid flow pipe downstream of the baffle, it tries to push the hollow fiber membranes into the openings. However, a space-forming member having a plurality of through holes formed therein is disposed between the liquid flow pipe and the plurality of hollow fiber membranes, and the space-forming member forms a communication space between the liquid flow pipe and at least one of the plurality of openings located between the baffle and the first fixing portion in the extension direction. Therefore, even if a hollow fiber membrane is pushed into a through hole located above an opening, i.e., even if a hollow fiber membrane is clogged in a through hole located overlapping the opening, the liquid is guided through the communication space to the opening from a through hole located away from the opening. This reduces pressure loss of the liquid.

[0009] [2] In the hollow fiber membrane element described in [1], the liquid distribution pipe may have a first pipe section located between the first fixing section and the baffle in the extension direction and a second pipe section located between the second fixing section and the baffle in the extension direction, the space-forming member may cover at least the first pipe section, and the communicating space may connect the openings of the multiple openings covered by the space-forming member to the multiple through-holes. In this hollow fiber membrane element, the space-forming member covers at least the first pipe section, and the communicating space connects the openings of the multiple openings covered by the space-forming member to the multiple through-holes. This can further reduce liquid pressure loss.

[0010] [3] In the hollow fiber membrane element according to [1] or [2], the space-forming member may extend from the first fixing portion to the second fixing portion, and the first fixing portion and the second fixing portion may fix the space-forming member to the liquid distribution pipe. In this hollow fiber membrane element, the space-forming member extends from the first fixing portion to the second fixing portion, and the first fixing portion and the second fixing portion fix the space-forming member to the liquid distribution pipe, so that the space-forming member can be easily attached and the pressure loss of the liquid can be further reduced.

[0011] [4] In the hollow fiber membrane element according to any one of [1] to [3], the surface of the space-forming member facing the liquid circulation pipe may be formed unevenly. In this hollow fiber membrane element, the surface of the space-forming member facing the liquid circulation pipe is formed unevenly, and this unevenness allows the formation of a communicating space.

[0012] [5] In the hollow fiber membrane element according to any one of [1] to [4], the opening area of ​​each of the plurality of through holes may be smaller than the opening area of ​​each of the plurality of openings. In this hollow fiber membrane element, the opening area of ​​each of the plurality of through holes is smaller than the opening area of ​​each of the plurality of openings. This makes it more difficult for the hollow fiber membrane to be pushed into the through holes than when a space-forming member is not provided and the hollow fiber membrane is pushed into the opening, or when the opening areas of the through holes and the openings are the same. This further reduces the pressure loss of the liquid.

[0013] [6] In the hollow fiber membrane element according to any one of [1] to [5], the number of the through holes may be greater than the number of the openings. In this hollow fiber membrane element, since the number of the through holes is greater than the number of the openings, many of the through holes can be arranged at positions farther away from the openings. This can further reduce the pressure loss of the liquid.

[0014] [7] In the hollow fiber membrane element according to any one of [1] to [6], the space-forming member may be formed in a mesh shape. In this hollow fiber membrane element, the space-forming member is formed in a mesh shape, so that the through holes can be arranged regularly. This allows liquid to be guided from a plurality of through holes to the opening over a wide area, further reducing the pressure loss of the liquid.

[0015] [8] In the hollow fiber membrane element described in any one of [1] to [7], the space-forming member may have a plurality of first linear portions extending in a first direction and a plurality of second linear portions extending in a second direction intersecting the first direction and connected to the plurality of first linear portions, and the plurality of through-holes may be formed between the plurality of first linear portions and the plurality of second linear portions. In this hollow fiber membrane element, the space-forming member has a plurality of first linear portions extending in the first direction and a plurality of second linear portions extending in the second direction and connected to the plurality of first linear portions, and the plurality of through-holes are formed between the plurality of first linear portions and the plurality of second linear portions. This allows the through-holes to be regularly arranged. This allows liquid to be guided from the plurality of through-holes to the opening over a wide area, further reducing pressure loss of the liquid.

[0016] [9] In the hollow fiber membrane element described in [8], the space-forming member may be configured such that the connection portions between the plurality of first linear portions and the plurality of second linear portions are thicker than the linear portions between the plurality of connection portions. In this hollow fiber membrane element, the space-forming member is configured such that the connection portions between the plurality of first linear portions and the plurality of second linear portions are thicker than the linear portions between the plurality of connection portions, so that the surface of the space-forming member facing the liquid distribution pipe can be easily formed unevenly.

[0017]

[10] The hollow fiber membrane element according to any one of [1] to [9] may further comprise an inter-membrane baffle that closes the space between the hollow fiber membranes in an intermediate portion of the element between the first and second fixing portions in the extension direction. This hollow fiber membrane element includes an inter-membrane baffle that closes the space between the hollow fiber membranes in the intermediate portion of the element. Because this hollow fiber membrane element includes an inter-membrane baffle that closes the space between the hollow fiber membranes in the intermediate portion of the element, the liquid that has flowed out of the liquid distribution pipe through an opening on the upstream side of the baffle can pass through the hollow fiber membranes, then pass through the hollow fiber membranes again, and return to the hollow portion of the liquid distribution pipe through an opening on the downstream side of the baffle. This allows the liquid to be in contact with the hollow fiber membranes for a longer period of time.

[0018]

[11] A hollow fiber membrane module according to the present disclosure comprises the hollow fiber membrane element according to any one of [1] to

[10] , a housing for accommodating the hollow fiber membrane element, a liquid supply port for supplying liquid from one side of the liquid circulation pipe to a hollow portion of the liquid circulation pipe, a liquid discharge port for discharging the liquid in the hollow portion of the liquid circulation pipe from the other side of the liquid circulation pipe, and a gas port communicating with the hollow portions of the plurality of hollow fiber membranes, and the region within the housing is partitioned by the plurality of hollow fiber membranes into an internal region including the hollow portions of the plurality of hollow fiber membranes and an external region including the hollow portion of the liquid circulation pipe.

[0019] In this hollow fiber membrane module, the hollow portion of the liquid circulation pipe is blocked by a baffle at an intermediate portion of the element between the first and second fixed portions in the extension direction. Therefore, when liquid is supplied from the liquid supply port, the liquid is supplied into the hollow portion of the liquid circulation pipe from one side, exits the liquid circulation pipe through an opening on the upstream side of the baffle, comes into contact with the plurality of hollow fiber membranes, returns to the hollow portion of the liquid circulation pipe through an opening on the downstream side of the baffle, and is discharged from the other side of the liquid circulation pipe to the liquid discharge port.

[0020] Here, when the liquid returns from the openings to the hollow portion of the liquid flow pipe downstream of the baffle, it tries to push the hollow fiber membranes into the openings. However, a space-forming member having a plurality of through holes formed therein is disposed between the liquid flow pipe and the plurality of hollow fiber membranes, and the space-forming member forms a communication space between the liquid flow pipe and at least one of the plurality of openings located between the baffle and the first fixing portion in the extension direction. Therefore, even if a hollow fiber membrane is pushed into a through hole located above an opening, i.e., even if a hollow fiber membrane is clogged in a through hole located overlapping the opening, the liquid is guided through the communication space to the opening from a through hole located away from the opening. This reduces pressure loss of the liquid.

[0021]

[12] A degassing method according to the present disclosure is a degassing method for degassing a liquid using the hollow fiber membrane module described in

[11] , in which a gas port of the hollow fiber membrane module is suctioned and a liquid is supplied to a liquid supply port of the hollow fiber membrane module. This degassing method uses a hollow fiber membrane module in which the above-mentioned hollow fiber membrane element is accommodated in a housing, and degasses the liquid by suctioning the gas port and supplying the liquid to the liquid supply port, thereby reducing pressure loss of the liquid.

[0022]

[13] A degassing method according to the present disclosure is a degassing method for degassing a liquid using the hollow fiber membrane module described in

[11] , in which a sweep gas is supplied to the gas port of the hollow fiber membrane module and a liquid is supplied to the liquid supply port of the hollow fiber membrane module. This degassing method uses a hollow fiber membrane module in which the above-mentioned hollow fiber membrane element is accommodated in a housing, and degasses the liquid by supplying a sweep gas to the gas port and a liquid to the liquid supply port, thereby reducing pressure loss of the liquid.

[0023]

[14] A gas addition method according to the present disclosure is a gas addition method for adding a gas to a liquid using the hollow fiber membrane module described in

[11] , in which a gas is supplied to a gas port of the hollow fiber membrane module to pressurize the hollow portions of the plurality of hollow fiber membranes, and a liquid is supplied to a liquid supply port of the hollow fiber membrane module. This gas addition method uses a hollow fiber membrane module in which the above-mentioned hollow fiber membrane elements are accommodated in a housing, and adds a gas to the liquid by supplying a gas to the gas port to pressurize the hollow portions of the plurality of hollow fiber membranes and supplying a liquid to the liquid supply port, thereby reducing pressure loss of the liquid.

[0024] According to the present disclosure, the pressure loss of the liquid can be reduced.

[0025] 1. A schematic cross-sectional view of a hollow fiber membrane element according to the present embodiment. A schematic cross-sectional view taken along line II-II in FIG. 1. A schematic cross-sectional view showing a portion of the hollow fiber membrane element shown in FIG. 1. A schematic cross-sectional view showing a portion of the hollow fiber membrane element shown in FIG. 1. A perspective view showing an example of a space-forming member. A perspective view showing an example of a space-forming member. A schematic enlarged view of a portion of an example of a space-forming member. A cross-sectional view taken along line VIII-VIII in FIG. 7. A cross-sectional view taken along line IX-IX in FIG. 7. A cross-sectional view taken along line XX in FIG. 7. A cross-sectional view taken along line XI-XI in FIG. 7. A schematic cross-sectional view of a hollow fiber membrane module according to the present embodiment. A schematic cross-sectional view showing the flow of liquid in the hollow fiber membrane module shown in FIG. 12. A schematic cross-sectional view of a modified hollow fiber membrane module.

[0026] Hereinafter, the hollow fiber membrane element, hollow fiber membrane module, degassing method, and gas addition method according to the embodiments will be described with reference to the drawings. In all the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0027] [Hollow fiber membrane element] Fig. 1 is a schematic cross-sectional view of a hollow fiber membrane element according to this embodiment. Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a schematic cross-sectional view showing a portion of the hollow fiber membrane element shown in Fig. 1. Fig. 4 is a schematic cross-sectional view showing a portion of the hollow fiber membrane element shown in Fig. 1. As shown in Figs. 1 to 4, the hollow fiber membrane element 2 according to this embodiment is used to degas a liquid L or to add a gas to the liquid L, and is incorporated into a hollow fiber membrane module, which will be described later, for example. The liquid L is not particularly limited, and examples thereof include seawater, drinking water, pure water, ultrapure water, and other water; aqueous solutions in which ammonium sulfate, surfactants, and the like are dissolved; organic solvents such as alcohols and hydrocarbons; and ionic liquids. The gas added to the liquid L is not particularly limited, and examples thereof include carbon dioxide (CO ２ ), nitrogen (N ２ The hollow fiber membrane element 2 includes a liquid distribution pipe 21, a plurality of hollow fiber membranes 22, a space forming member 23, a first fixing part 24, and a second fixing part 25.

[0028] The liquid circulation pipe 21 is a cylindrical member extending in the extension direction D to support a plurality of hollow fiber membranes 22. Of the two extension directions D, one direction is referred to as a first extension direction D1, and the other direction is referred to as a second extension direction D2. In FIG. 1 , the upper side is the first extension direction D1, and the lower side is the second extension direction D2. The end of the hollow fiber membrane element 2 on the first extension direction D1 side is referred to as a first element end 2a, and the end of the hollow fiber membrane element 2 on the second extension direction D2 side is referred to as a second element end 2b. The liquid circulation pipe 21 has enough rigidity to support a plurality of hollow fiber membranes 22.

[0029] The hollow portion 21a of the liquid circulation pipe 21 is a flow path (intra-pipe flow path) through which the liquid L can flow, and is formed by the inner circumferential surface of the liquid circulation pipe 21. The liquid circulation pipe 21 extends over the entire area in the extension direction D of the hollow fiber membrane element 2. That is, the liquid circulation pipe 21 extends 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 portion 21a of the liquid circulation pipe 21 is open in the first extension direction D1 and the second extension direction D2. The opening of the hollow portion 21a of the liquid circulation pipe 21 at the first element end 2a, i.e., the opening on the first extension direction D1 side of the hollow portion 21a of the liquid circulation pipe 21, is referred to as the first end liquid circulation pipe opening 21b. The opening of the hollow portion 21 a of the liquid flow pipe 21 at the second element end 2 b, i.e., the opening of the hollow portion 21 a of the liquid flow pipe 21 on the second extension direction D2 side, is referred to as a second-end liquid flow pipe opening 21 c. A baffle 26 is provided in the hollow portion 21 a of the liquid flow pipe 21. Details of the baffle 26 will be described later.

[0030] A plurality of openings 21d are formed in the liquid circulation pipe 21. The plurality of openings 21d are holes for allowing the liquid L to circulate between the hollow portion 21a and the outside of the liquid circulation pipe 21, separate from the first end liquid circulation pipe opening 21b and the second end liquid circulation pipe opening 21c. In other words, the plurality of openings 21d are holes for allowing the liquid L to pass through the liquid circulation pipe 21 in the radial direction of the liquid circulation pipe 21. The plurality of openings 21d are formed in the peripheral wall of the liquid circulation pipe 21, and open the hollow portion 21a to the outside of the liquid circulation pipe 21.

[0031] The plurality of hollow fiber membranes 22 extend along the liquid circulation pipe 21 and are arranged around the liquid circulation pipe 21 so as to cover the plurality of openings 21d. The plurality of hollow fiber membranes 22 extending along the liquid circulation pipe 21 means that in the initial state (unused state) of the hollow fiber membrane element 2, the plurality of hollow fiber membranes 22 extend along the extension direction D. The plurality of hollow fiber membranes 22 form a membrane bundle having a substantially cylindrical shape as a whole.

[0032] The plurality of hollow fiber membranes 22 are formed, for example, by a hollow fiber membrane fabric (not shown) woven in the shape of a bamboo blind. The hollow fiber membrane fabric is a fabric in which a plurality of hollow fiber membranes 22 serving as weft threads are woven with warp threads (not shown). In the hollow fiber membrane fabric, the plurality of hollow fiber membranes 22 are arranged in the shape of a bamboo blind. The hollow fiber membrane fabric is then wound around the liquid distribution pipe 21 so that the plurality of hollow fiber membranes 22 extend in the extension direction D and cover the plurality of openings 21 d. The hollow fiber membrane fabric is wound around the liquid distribution pipe 21 by, for example, gripping the liquid distribution pipe 21 with a chuck and rotating the liquid distribution pipe 21 together with the chuck.

[0033] The hollow portions 22a of the hollow fiber membranes 22 are flow paths (intra-membrane flow paths) through which gas can flow, and are formed by the inner circumferential surfaces of the hollow fiber membranes 22. The plurality of hollow fiber membranes 22 extend across the entire extension direction D of the hollow fiber membrane element 2. That is, the plurality of 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 plurality of hollow fiber membranes 22 are open in the first extension direction D1 and the second extension direction D2. Note that the hollow portions 22a of the plurality of hollow fiber membranes 22 refer to the respective hollow portions 22a of the plurality of hollow fiber membranes 22. The openings of the hollow portions 22a of the plurality of hollow fiber membranes 22 at the first element end portion 2a, i.e., the openings of the hollow portions 22a of the plurality of hollow fiber membranes 22 on the first extension direction D1 side, are referred to as first end hollow fiber membrane openings 22b. The openings of the hollow portions 22a of the plurality of hollow fiber membranes 22 at the second element end 2b, i.e., the openings of the hollow portions 22a of the plurality of hollow fiber membranes 22 on the second extending direction D2 side, are referred to as second end hollow fiber membrane openings 22c.

[0034] The hollow fiber membrane 22 is a hollow fiber-shaped membrane that allows gas to pass through but not liquid L. The material, shape, and form of the hollow fiber membrane 22 are not particularly limited. Examples of materials for the hollow fiber membrane 22 include polyolefin-based resins such as polypropylene, polyethylene, and polymethylpentene; silicone-based resins such as polydimethylsiloxane and its copolymers; and fluorine-based resins such as PTFE and vinylidene fluoride. Examples of the membrane shape (sidewall shape) of the hollow fiber membrane 22 include porous membranes, microporous membranes, and homogeneous membranes (non-porous membranes) that do not have porosity. Examples of the membrane form of the hollow fiber membrane 22 include symmetric membranes (homogeneous membranes) in which the entire membrane has a homogeneous chemical or physical structure, and asymmetric membranes (heterogeneous membranes) in which the chemical or physical structure of the membrane varies depending on the membrane. An asymmetric 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 of the membrane or inside the porous membrane. Heterogeneous membranes also include composite membranes with different chemical structures and multilayer membranes such as three-layer structures. In particular, heterogeneous membranes using poly(4-methylpentene-1) resin are particularly preferred because they have a dense layer that blocks liquid L.

[0035] 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.

[0036] The first fixing portion 24 is located at the first element end portion 2a and fixes the plurality of hollow fiber membranes 22 to the liquid circulation pipe 21 so as to seal the gap between the liquid circulation pipe 21 and the plurality of hollow fiber membranes 22 and leave the hollow portion 21a of the liquid circulation pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. In other words, the first fixing portion 24 fixes the end of the plurality of hollow fiber membranes 22 on the first extension direction D1 side to the liquid circulation pipe 21. The first fixing portion 24 also seals the gap between the liquid circulation pipe 21 and the plurality of hollow fiber membranes 22. Furthermore, the first fixing portion 24 is not provided in the hollow portion 21a of the liquid circulation pipe 21 or the hollow portions 22a of the plurality of hollow fiber membranes 22, leaving the hollow portion 21a of the liquid circulation pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. The first fixing portion 24 is formed of, for example, resin.

[0037] The second fixing portion 25 is located at the second element end portion 2b and fixes the plurality of hollow fiber membranes 22 to the liquid circulation pipe 21 so as to seal the gap between the liquid circulation pipe 21 and the plurality of hollow fiber membranes 22 and leave the hollow portion 21a of the liquid circulation pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. In other words, the second fixing portion 25 fixes the ends of the plurality of hollow fiber membranes 22 on the second extension direction D2 side to the liquid circulation pipe 21. The second fixing portion 25 seals the gap between the liquid circulation pipe 21 and the plurality of hollow fiber membranes 22. Furthermore, the second fixing portion 25 is not provided in the hollow portion 21a of the liquid circulation pipe 21 or the hollow portions 22a of the plurality of hollow fiber membranes 22, leaving the hollow portion 21a of the liquid circulation pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. The second fixing portion 25 is formed of, for example, resin.

[0038] The baffle 26 blocks the flow of the liquid L in the hollow portion 21a of the liquid circulation pipe 21 in the extension direction D. The baffle 26 closes the hollow portion 21a of the liquid circulation pipe 21 at an element intermediate portion 2c between the first fixed portion 24 and the second fixed portion 25 in the extension direction D. The element intermediate portion 2c is located at any position between the first fixed portion 24 and the second fixed portion 25 in the extension direction D, but may be, for example, the center portion between the first fixed portion 24 and the second fixed portion 25 in the extension direction D. Here, the portion of the liquid circulation pipe 21 located between the first fixed portion 24 and the baffle 26 in the extension direction D is referred to as a first pipe portion 211. Furthermore, the portion of the liquid circulation pipe 21 located between the second fixed portion 25 and the baffle 26 in the extension direction D is referred to as a second pipe portion 212.

[0039] The space forming member 23 has a plurality of through holes 23a formed therein and is disposed between the liquid flow pipe 21 and the plurality of hollow fiber membranes 22. The space forming member 23 is formed in a cylindrical shape extending in the extension direction D. The space forming member 23 may be formed of a pipe-shaped member, or may be wound around the liquid flow pipe 21.

[0040] The plurality of through holes 23a are holes for allowing the liquid L to circulate between the liquid circulation pipe 21 and the plurality of hollow fiber membranes 22. In other words, the plurality of through holes 23a are holes for allowing the liquid L to pass through the space forming member 23 in the radial direction of the space forming member 23. The plurality of through holes 23a are formed in the peripheral wall of the space forming member 23.

[0041] The opening area of ​​each of the plurality of through holes 23a is smaller than the opening area of ​​each of the plurality of openings 21d. The opening area of ​​each of the plurality of through holes 23a is not particularly limited, but may be, for example, 0.1 mm ２ More than 50 mm ２ The number of the through holes 23a is, for example, greater than the number of the openings 21d. The number of the through holes 23a per unit area is not particularly limited, but may be, for example, 1 / cm. ２ More than 200 pieces / cm ２ It can be as follows:

[0042] The space forming member 23 covers at least a portion of the liquid flow pipe 21 between the baffle 26 and the first fixing portion 24 in the extension direction D so as to cover at least one of the multiple openings 21d located between the baffle 26 and the first fixing portion 24 in the extension direction D. In this embodiment, the space forming member 23 covers at least the first pipe portion 211 so as to cover at least all of the openings 21d formed in the first pipe portion 211. The space forming member 23 also extends from the first fixing portion 24 to the second fixing portion 25 so as to cover all of the openings 21d formed in the liquid flow pipe 21. The space forming member 23 also extends 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, covering the entire liquid flow pipe 21. The space forming member 23, together with the multiple hollow fiber membranes 22, is fixed to the liquid flow pipe 21 by the first fixing portion 24 and the second fixing portion 25.

[0043] 5 and 6 are perspective views showing examples of the space forming member. The space forming member 23 shown in Fig. 5 and Fig. 6 has a plurality of first linear portions 231a extending in a first direction d1 (see Fig. 7) and a plurality of second linear portions 231b extending in a second direction d2 (see Fig. 7) intersecting the first direction d1 and connected to the plurality of first linear portions 231a. The plurality of first linear portions 231a and the plurality of second linear portions 231b form a plurality of meshes, and these plurality of meshes serve as a plurality of through holes 23a.

[0044] In the space forming member 23 shown in FIG. 5 , the direction parallel to the central axis of the space forming member 23 is the first direction d1, and the circumferential direction around the central axis of the space forming member 23 is the second direction d2. The space forming member 23 shown in FIG. 5 includes a plurality of first linear portions 231a extending in a direction parallel to the central axis of the space forming member 23, and a plurality of second linear portions 231b extending in a circular shape centered on the central axis of the space forming member 23 and connected to the plurality of first linear portions 231a. The plurality of first linear portions 231a are arranged in a circular shape around the central axis of the space forming member 23. The plurality of second linear portions 231b are arranged in a direction parallel to the central axis of the space forming member 23. In other words, in the space forming member 23 shown in FIG. 5 , the plurality of first linear portions 231a and the plurality of second linear portions 231b are connected in a lattice pattern. The mesh formed between the plurality of first linear portions 231 a and the plurality of second linear portions 231 b constitutes the plurality of through holes 23 a. The shape of the through holes 23 a of the space forming member 23 shown in FIG. 5 is square.

[0045] In the space forming member 23 shown in FIG. 6 , a direction inclined at a predetermined angle with respect to a direction parallel to the central axis of the space forming member 23 is the first direction d1, and a direction inclined at a predetermined angle in the opposite direction from the first direction d1 with respect to a direction parallel to the central axis of the space forming member 23 is the second direction d2. The space forming member 23 shown in FIG. 6 is configured with a plurality of first linear portions 231a extending in a direction inclined at a predetermined angle with respect to a direction parallel to the central axis of the space forming member 23, and a plurality of second linear portions 231b extending in a direction inclined at a predetermined angle with respect to a direction parallel to the central axis of the space forming member 23 in the opposite direction from the first linear portions 231a and connected to the plurality of first linear portions 231a. The plurality of first linear portions 231a are arranged in a direction parallel to the central axis of the space forming member 23. The plurality of second linear portions 231b are also arranged in a direction parallel to the central axis of the space forming member 23. 6, the plurality of first linear portions 231a and the plurality of second linear portions 231b are connected in a diagonal lattice pattern. The mesh formed between the plurality of first linear portions 231a and the plurality of second linear portions 231b constitutes the plurality of through holes 23a. The shape of the through holes 23a of the space forming member 23 shown in FIG. 6 is a rhombuses.

[0046] From the viewpoint of ease of manufacture, the space forming member 23 is preferably made of resin. Examples of resins used for the space forming member 23 include polypropylene and polyethylene, and preferably ultra-high molecular weight polyethylene and high density polyethylene.

[0047] As shown in FIGS. 2 to 4 , the space forming member 23 forms a communication space 23b between the liquid circulation pipe 21 and at least one of the plurality of openings 21d that is located between the baffle 26 and the first fixing portion 24 in the extension direction D, and the plurality of through holes 23a. In this embodiment, the space forming member 23 forms the communication space 23b that communicates at least all of the openings 21d formed in the first pipe portion 211 with the plurality of through holes 23a. The space forming member 23 also forms the communication space 23b that communicates all of the openings 21d formed in the liquid circulation pipe 21 with the plurality of through holes 23a. The communication space 23b is a space formed between the liquid circulation pipe 21 and the space forming member 23. The communication space 23b also functions as a communication passage that communicates at least one of the openings 21d with the plurality of through holes 23a.

[0048] The communication space 23b may communicate all of the through holes 23a formed in the space forming member 23 with all of the openings 21d formed in the liquid flow pipe 21. The communication space 23b may also communicate all of the through holes 23a formed in the space forming member 23 with a plurality of openings 21d formed in a portion of the liquid flow pipe 21. The communication space 23b may also communicate the plurality of through holes 23a formed in a portion of the space forming member 23 with all of the openings 21d formed in the liquid flow pipe 21. The communication space 23b may also communicate the plurality of through holes 23a formed in a portion of the space forming member 23 with a plurality of openings 21d formed in a portion of the liquid flow pipe 21.

[0049] The number of communication spaces 23b formed by the space forming member 23 may be one or more. When the space forming member 23 forms multiple communication spaces 23b, some of the multiple through holes 23a out of all the through holes 23a formed in the space forming member 23 communicate with each communication space 23b.

[0050] FIG. 7 is a schematic diagram showing an enlarged portion of an example of a space forming member. FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 7. FIG. 10 is a cross-sectional view taken along line X-X in FIG. 7. FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 7. FIGS. 8 to 11 also show the liquid circulation pipe 21. The space forming member 23 shown in FIGS. 7 to 11 has a plurality of first linear portions 231a extending in a first direction d1 and a plurality of second linear portions 231b extending in a second direction d2 intersecting the first direction d1 and connected to the plurality of first linear portions 231a. The plurality of meshes formed by the plurality of first linear portions 231a and the plurality of second linear portions 231b constitute a plurality of through-holes 23a.

[0051] 7 to 11, the surface 23c on the liquid flow pipe 21 side is formed unevenly, and the surface 23d on the hollow fiber membrane 22 side is formed as a flat curved surface (a shape corresponding to the outer peripheral surface of a cylinder). The connection portions 23e between the first linear portions 231a and the second linear portions 231b are thicker than the linear portions 23f between the connection portions 23e. The linear portions 23f are, for example, portions located in the center between adjacent connection portions 23e.

[0052] The thickness of the space forming member 23 can be appropriately set to a degree that allows the formation of the communicating space 23b, and can be, for example, 0.3 mm to 5 mm, preferably 0.35 mm to 4 mm, and more preferably 0.4 mm to 3 mm. The thickness of the space forming member 23 is the maximum thickness of the space forming member 23.

[0053] The plurality of hollow fiber membranes 22 are not covered by a member such as a housing, and are exposed to the outside of the hollow fiber membrane element 2 between the first fixing part 24 and the second fixing part 25 .

[0054] [Hollow fiber membrane module] Next, the hollow fiber membrane module according to this embodiment will be described. The hollow fiber membrane module according to this embodiment is a module for degassing the liquid L or adding a gas to the liquid L. Fig. 12 is a schematic cross-sectional view of the hollow fiber membrane module according to this embodiment. As shown in Fig. 12, the hollow fiber membrane module 1 comprises the hollow fiber membrane element 2 according to the embodiment described above and a housing 3.

[0055] The housing 3 accommodates the hollow fiber membrane element 2 so that a space is formed between the hollow fiber membrane elements 2 and the plurality of hollow fiber membranes 22. This space is a space between the hollow fiber membrane element 2 and the housing 3 through which the liquid L can flow.

[0056] The housing 3 includes 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 the first lid portion 32. The hollow fiber membrane element 2 is housed in the cylindrical portion 31 so that the extending direction D of the hollow fiber membrane element 2 is the extending direction of the cylindrical portion 31, i.e., 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 the same direction, and therefore the extending direction of the cylindrical portion 31 is also referred to as the extending direction D.

[0057] The first fixing portion 24 and the second fixing portion 25 are airtightly attached to the cylindrical portion 31. That is, 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 maintained airtight. Therefore, the area inside the housing 3 is divided into an inner region R1 and an outer region R2 by the plurality of hollow fiber membranes 22 as a boundary. The outer region R2 is an area including the hollow portions 21a of the liquid distribution pipe 21 and is a liquid phase area to which the liquid L is supplied. The inner region R1 is an area including the hollow portions 22a of the plurality of hollow fiber membranes 22 and is a gas phase area through which gas degassed from the liquid L flows. Therefore, the hollow fiber membranes 22 form a boundary between the inner region R1, which is a gas phase area, and the outer region R2, which is a liquid phase area. That is, the inside of the hollow fiber membranes 22 (hollow portions 22a) is the inner region R1, and the outside of the hollow fiber membranes 22 is the outer region R2. The hollow fiber membranes 22 prevent the liquid L from permeating from the outer region R2 to the inner region R1, and allow the gas to permeate from the outer region R2 to the inner region R1.

[0058] The first fixing portion 24 and the second fixing portion 25 may be attached to the cylindrical portion 31 so as to be detachable from 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.

[0059] The first lid portion 32 is attached to the end portion 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 32a between itself and the hollow fiber membrane element 2, which is in communication with the hollow portions 22a of the plurality of 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, or the like.

[0060] The second lid portion 33 is attached to the end portion 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 lid portion 33 forms a second communication space 33a between itself and the hollow fiber membrane element 2, which is in communication with the hollow portions 22a of the plurality of hollow fiber membranes 22. The second lid 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 lid portion 33 can be attached to the cylindrical portion 31 by, for example, screwing, fitting, or the like.

[0061] The housing 3 has a liquid supply port 3a for supplying the liquid L to the hollow portion 21a of the liquid circulation pipe 21, a liquid discharge port 3b for discharging the liquid L that has come out of the hollow portion 21a of the liquid circulation pipe 21, and a first gas port 3c and a second gas port 3d that communicate with the hollow portions 22a of the plurality of hollow fiber membranes 22. The liquid supply port 3a, the liquid discharge port 3b, the first gas port 3c, and the second gas port 3d may be configured integrally with the housing 3 or may be separate members from the housing 3.

[0062] The liquid supply port 3a is provided in the second lid portion 33 and is a port that communicates between the inside and outside of the housing 3. The liquid supply port 3a extends in a pipe shape from the second lid portion 33 to the inside of the housing 3 and is connected to the end 21e of the liquid circulation pipe 21 on the side of the second extension direction D2. The liquid supply port 3a is in communication with the hollow portion 21a of the liquid circulation pipe 21.

[0063] The liquid discharge port 3b is a port that is provided in the first cover portion 32 and that communicates between the inside and outside of the housing 3. The liquid discharge port 3b extends in a pipe shape from the first cover portion 32 to the inside of the housing 3, and is connected to the end portion 21f of the liquid circulation pipe 21 on the side in the first extension direction D1. The liquid discharge port 3b is in communication with the hollow portion 21a of the liquid circulation pipe 21.

[0064] The first gas port 3c is a port that is provided in the first cover portion 32 and that communicates between the inside and the outside of the housing 3. The first gas port 3c is adjacent to the first communication space 32a and is in communication with the first communication space 32a.

[0065] The second gas port 3d is a port that is provided in the second cover portion 33 and that communicates between the inside and the outside of the housing 3. The second gas port 3d is adjacent to the second communication space 33a and is in communication with the second communication space 33a.

[0066] [First Degassing Method: Vacuum Mode] Next, the first degassing method according to this embodiment will be described. The first degassing method according to this embodiment is a method of degassing the liquid L using the hollow fiber membrane module 1 in vacuum mode.

[0067] 12 , in this first degassing method, the first gas port 3c and the second gas port 3d of the hollow fiber membrane module 1 are suctioned, and liquid L is supplied to the liquid supply port 3a of the hollow fiber membrane module 1. Suction of the first gas port 3c and the second gas port 3d can be performed, for example, by connecting a suction device (not shown) such as a vacuum pump to the first gas port 3c and the second gas port 3d via piping or the like and operating this suction device. Supply of liquid L to the liquid supply port 3a can be performed, for example, by connecting a liquid supply device (not shown) such as a liquid feed pump that delivers liquid L via piping or the like to the liquid supply port 3a and operating this liquid supply device.

[0068] When the first gas port 3 c and the second gas port 3 d are suctioned, the internal region R1 connected to the first gas port 3 c and the second gas port 3 d is suctioned, and the internal region R1 is decompressed. When the liquid L is supplied to the liquid supply port 3 a, the liquid L is supplied to the external region R2 connected to the liquid supply port 3 a.

[0069] FIG. 13 is a schematic cross-sectional view showing the flow of liquid in the hollow fiber membrane module shown in FIG. 12 . As shown in FIGS. 12 and 13 , liquid L supplied to the liquid supply port 3 a is supplied to the hollow portion 21 a of the liquid flow pipe 21 from the second end liquid flow pipe opening 21 c side. Thereafter, because the baffle 26 blocks the flow of liquid L in the extension direction D, the liquid L exits the liquid flow pipe 21 through the multiple openings 21 d on the upstream side of the baffle 26 (the second end liquid flow pipe opening 21 c side). The liquid L then passes through the space-forming member 23 at the multiple through-holes 23 a and comes into contact with the multiple hollow fiber membranes 22. At this time, because the hollow portions 22 a of the multiple hollow fiber membranes 22 are in a depressurized state, gases such as dissolved gas in the liquid L and gas bubbles contained in the liquid L permeate the multiple hollow fiber membranes 22 and are discharged from the first gas port 3 c and the second gas port 3 d. This degassing the liquid L. Thereafter, the liquid L passes through the space forming member 23 at the plurality of through holes 23a on the downstream side of the baffle 26 (the first end liquid circulation pipe opening 21b side) and returns to the hollow portion 21a of the liquid circulation pipe 21 through the plurality of openings 21d. Thereafter, the liquid L is discharged from the liquid discharge port 3b.

[0070] [Second Degassing Method: Sweep Mode] Next, the second degassing method according to this embodiment will be described. The second degassing method according to this embodiment is a method of degassing the liquid L using the hollow fiber membrane module 1 in sweep mode.

[0071] As shown in Figure 12, in this second degassing method, a sweep gas is supplied to the first gas port 3c of the hollow fiber membrane module 1, and liquid L is supplied to the liquid supply port 3a of the hollow fiber membrane module 1. Examples of the sweep gas include air (dry air), nitrogen gas, argon gas, and other inert gases. The sweep gas may be supplied to the second gas port 3d instead of the first gas port 3c. The supply of the sweep gas to the first gas port 3c can be achieved, for example, by connecting a gas supply device (not shown) such as a gas cylinder and regulator to the first gas port 3c via piping or the like and operating this gas supply device. The supply of liquid L to the liquid supply port 3a can be achieved, for example, by connecting a liquid supply device (not shown) such as a liquid pump that delivers liquid L via piping or the like to the liquid supply port 3a and operating this liquid supply device.

[0072] When a sweep gas is supplied to the first gas port 3c, the sweep gas flows from the first gas port 3c to the second gas port 3d through the hollow portions 22a of the hollow fiber membranes 22 and is discharged from the second gas port 3d. When a liquid L is supplied to the liquid supply port 3a, the liquid L is supplied to the external region R2 that is connected to the liquid supply port 3a.

[0073] As shown in Figures 12 and 13, the liquid L supplied to the liquid supply port 3a is supplied from the second-end liquid circulation pipe opening 21c side to the hollow portion 21a of the liquid circulation pipe 21. Thereafter, because the baffle 26 prevents the liquid L from flowing in the extension direction D, the liquid L exits the liquid circulation pipe 21 through the multiple openings 21d on the upstream side of the baffle 26 (the second-end liquid circulation pipe opening 21c side). The liquid L then passes through the space-forming member 23 at the multiple through-holes 23a 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 swept by the sweep gas, causing dissolved gas in the liquid L and gases such as bubbles contained in the liquid L to permeate the multiple hollow fiber membranes 22 and be discharged from the second gas port 3d together with the sweep gas. This degassing the liquid L. Thereafter, the liquid L passes through the space forming member 23 at the plurality of through holes 23a on the downstream side of the baffle 26 (the first end liquid circulation pipe opening 21b side) and returns to the hollow portion 21a of the liquid circulation pipe 21 through the plurality of openings 21d. Thereafter, the liquid L is discharged from the liquid discharge port 3b.

[0074] [Third Degassing Method: Combo Mode] Next, a third degassing method according to this embodiment will be described. The third degassing method according to this embodiment is a method of degassing the liquid L using the hollow fiber membrane module 1 in a combo mode that combines a sweep mode and a vacuum mode.

[0075] As shown in Figure 12, in this third degassing method, a sweep gas is supplied to the first gas port 3c of the hollow fiber membrane module 1, and the second gas port 3d of the hollow fiber membrane module 1 is suctioned, while the liquid L is supplied to the liquid supply port 3a of the hollow fiber membrane module 1. Alternatively, a sweep gas may be supplied to the second gas port 3d and the first gas port 3c is suctioned. The supply of the sweep gas to the first gas port 3c can be performed, for example, by connecting a gas supply device (not shown) such as a gas cylinder and regulator to the first gas port 3c via piping or the like and operating this gas supply device. The suction of the second gas port 3d can be performed, for example, by connecting a suction device (not shown) such as a vacuum pump to the second gas port 3d via piping or the like and operating this suction device. The supply of the liquid L to the liquid supply port 3a can be performed, for example, by connecting a liquid supply device (not shown) such as a liquid feed pump that delivers the liquid L via piping or the like to the liquid supply port 3a and operating this liquid supply device.

[0076] When a sweep gas is supplied to the first gas port 3c, the sweep gas flows from the first gas port 3c to the second gas port 3d through the hollow portions 22a of the hollow fiber membranes 22. When the second gas port 3d is suctioned, the inner region R1 connected to the second gas port 3d is suctioned, and the sweep gas supplied to the hollow portions 22a of the hollow fiber membranes 22 is discharged from the second gas port 3d. When a liquid L is supplied to the liquid supply port 3a, the liquid L is supplied to the outer region R2 connected to the liquid supply port 3a.

[0077] As shown in Figures 12 and 13, the liquid L supplied to the liquid supply port 3a is supplied from the second-end liquid flow pipe opening 21c side to the hollow portion 21a of the liquid flow pipe 21. Thereafter, because the baffle 26 prevents the liquid L from flowing in the extension direction D, the liquid L exits the liquid flow pipe 21 through the multiple openings 21d on the upstream side of the baffle 26 (the second-end liquid flow pipe opening 21c side). The liquid L then passes through the space-forming member 23 at the multiple through-holes 23a 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 swept by the sweep gas, and the liquid L is sucked through the second gas port 3d. This causes dissolved gas in the liquid L, gas bubbles contained in the liquid L, and other gases to permeate the multiple hollow fiber membranes 22 and be discharged from the second gas port 3d together with the sweep gas. This degassing the liquid L. Thereafter, the liquid L passes through the space forming member 23 at the plurality of through holes 23a on the downstream side of the baffle 26 (the first end liquid circulation pipe opening 21b side) and returns to the hollow portion 21a of the liquid circulation pipe 21 through the plurality of openings 21d. Thereafter, the liquid L is discharged from the liquid discharge port 3b.

[0078] [Gas Addition Method] Next, the gas addition method according to this embodiment will be described. The gas addition method according to this embodiment is a method of adding a gas to the liquid L using the hollow fiber membrane module 1.

[0079] 12 , in this gas addition method, gas is supplied to the first gas port 3 c and the second gas port 3 d of the hollow fiber membrane module 1, and liquid L is supplied to the liquid supply port 3 a of the hollow fiber membrane module 1. The supply of gas to the first gas port 3 c and the second gas port 3 d can be performed, for example, by connecting a gas supply device (not shown) such as a compressor to the first gas port 3 c and the second gas port 3 d via piping or the like and operating this gas supply device. The supply of liquid L to the liquid supply port 3 a can be performed, for example, by connecting a liquid supply device (not shown) such as a liquid supply pump that delivers liquid L via piping or the like to the liquid supply port 3 a and operating this liquid supply device.

[0080] When gas is supplied to the first gas port 3c and the second gas port 3d, the gas is supplied to the hollow portions 22a of the plurality of hollow fiber membranes 22 connected to the first gas port 3c and the second gas port 3d, and the hollow portions 22a of the plurality of hollow fiber membranes 22 are pressurized. In other words, the gas is supplied to the first gas port 3c and the second gas port 3d so that the gas supplied to the first gas port 3c and the second gas port 3d pressurizes the hollow portions 22a of the plurality of hollow fiber membranes 22. Furthermore, when liquid L is supplied to the liquid supply port 3a, the liquid L is supplied to the external region R2 connected to the liquid supply port 3a.

[0081] 12 and 13 , the liquid L supplied to the liquid supply port 3a is supplied from the second-end liquid flow pipe opening 21c side to the hollow portion 21a of the liquid flow pipe 21. Thereafter, because the baffle 26 prevents the liquid L from flowing in the extension direction D, the liquid L exits the liquid flow pipe 21 through the multiple openings 21d on the upstream side of the baffle 26 (the second-end liquid flow pipe opening 21c side). The liquid L then passes through the space-forming member 23 at the multiple through-holes 23a 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 pressurized by the gas supplied from the first gas port 3c and the second gas port 3d, so the gas permeates the multiple hollow fiber membranes 22 and comes into contact with the liquid L. This causes the gas to be added to the liquid L. Thereafter, the liquid L passes through the space forming member 23 at the plurality of through holes 23a on the downstream side of the baffle 26 (the first end liquid circulation pipe opening 21b side) and returns to the hollow portion 21a of the liquid circulation pipe 21 through the plurality of openings 21d. Thereafter, the liquid L is discharged from the liquid discharge port 3b.

[0082] As described above, in the hollow fiber membrane element 2 according to this embodiment, the hollow portion 21 a of the liquid circulation pipe 21 is blocked by the baffle 26 in the element intermediate portion 2 c between the first fixing portion 24 and the second fixing portion 25 in the extension direction D. Therefore, in the hollow fiber membrane module 1 in which this hollow fiber membrane element 2 is accommodated in the housing 3, when the liquid L is supplied from one side of the liquid circulation pipe 21 (the second end liquid circulation pipe opening 21 c side) to the hollow portion 21 a of the liquid circulation pipe 21, the liquid L exits the liquid circulation pipe 21 from the opening 21 d on the upstream side of the baffle 26 (the second end liquid circulation pipe opening 21 c side) and comes into contact with the plurality of hollow fiber membranes 22, returns to the hollow portion 21 a of the liquid circulation pipe 21 from the opening 21 d on the downstream side of the baffle 26 (the first end liquid circulation pipe opening 21 b side), and is discharged from the other side of the liquid circulation pipe 21 (the first end liquid circulation pipe opening 21 b side).

[0083] Here, when the liquid L returns from the opening 21d to the hollow portion 21a of the liquid flow pipe 21 downstream of the baffle 26, it tries to push the hollow fiber membranes 22 into the opening 21d. However, the space-forming member 23, having a plurality of through holes 23a formed therein, is disposed between the liquid flow pipe 21 and the plurality of hollow fiber membranes 22, and the space-forming member 23 forms a communication space 23b between the liquid flow pipe 21 and at least one of the plurality of openings 21d that is located between the baffle 26 and the first fixing portion 24 in the extension direction D and the plurality of through holes 23a. Therefore, even if the hollow fiber membrane 22 is pushed into the through hole 23a located above the opening 21d, i.e., even if the hollow fiber membrane 22 is clogged in the through hole 23a located in a position overlapping the opening 21d, the liquid L is guided through the communication space 23b from the through hole 23a located away from the opening 21d to the opening 21d. This reduces the pressure loss of the liquid L.

[0084] Furthermore, in this hollow fiber membrane element 2, the space-forming member 23 covers at least the first pipe portion 211, and the communication space 23b connects the openings 21d that are covered by the space-forming member 23 with the plurality of through-holes 23a, among the plurality of openings 21d. Therefore, the pressure loss of the liquid L can be further reduced.

[0085] Furthermore, in this hollow fiber membrane element 2, the space-forming member 23 extends from the first fixing part 24 to the second fixing part 25, and the first fixing part 24 and the second fixing part 25 fix the space-forming member 23 to the liquid circulation pipe 21. This makes it possible to easily attach the space-forming member 23 and further reduce the pressure loss of the liquid L.

[0086] In addition, in this hollow fiber membrane element 2, the surface 23c of the space forming member 23 on the liquid circulation pipe 21 side is formed unevenly, and this unevenness can form the communicating space 23b.

[0087] Furthermore, in this hollow fiber membrane element 2, the surface 23d of the space-forming member 23 facing the multiple hollow fiber membranes 22 is formed into a flat curved surface, which prevents the multiple hollow fiber membranes 22 arranged on the space-forming member 23 from bending.

[0088] Furthermore, in this hollow fiber membrane element 2, the opening area of ​​each of the plurality of through holes 23a is smaller than the opening area of ​​each of the plurality of openings 21d, so the hollow fiber membranes 22 are less likely to be pushed into the through holes 23a than when the hollow fiber membranes 22 are pushed into the openings 21d without the space-forming member 23 or when the opening areas of the through holes 23a and the openings 21d are the same. This makes it possible to further reduce the pressure loss of the liquid L.

[0089] Furthermore, in this hollow fiber membrane element 2, the opening area of ​​each of the plurality of through holes 23a is smaller than the opening area of ​​each of the plurality of openings 21d. Therefore, the mechanical strength of the space-forming member 23 is improved compared to when the opening area ratio of the through holes 23a to the openings 21d is the same. This makes it possible to suppress, for example, deformation of the space-forming member 23 in a direction away from the liquid circulation pipe 21 due to the liquid L leaking from the openings 21d of the liquid circulation pipe 21. Therefore, for example, in a hollow fiber membrane module 1 in which this hollow fiber membrane element 2 is housed in a housing 3, it is possible to suppress the hollow fiber membranes 22 from being pressed against the housing 3 by the space-forming member 23.

[0090] Furthermore, in this hollow fiber membrane element 2, the opening area of ​​each of the plurality of through holes 23a is smaller than the opening area of ​​each of the plurality of openings 21d. Therefore, the contact area between the space forming member 23 and the plurality of hollow fiber membranes 22 can be increased compared to when the opening area ratio between the through holes 23a and the openings 21d is the same. This makes it possible to distribute, for example, the pressing force of the plurality of hollow fiber membranes 22 against the space forming member 23 caused by the liquid L flowing toward the openings 21d of the liquid circulation pipe 21. Therefore, damage to the plurality of hollow fiber membranes 22 due to being pressed against the space forming member 23 can be suppressed.

[0091] Furthermore, in this hollow fiber membrane element 2, the opening area of ​​each of the plurality of through holes 23a is smaller than the opening area of ​​each of the plurality of openings 21d. Therefore, the number of through holes 23a can be increased compared to when the opening area ratio of the through holes 23a to the openings 21d is the same. This allows, for example, the flow rate of the liquid L entering each through hole 23a to be reduced, making it even more difficult for the hollow fiber membranes 22 to be pushed into the through holes 23a.

[0092] Furthermore, in this hollow fiber membrane element 2, the opening area of ​​each of the plurality of through holes 23a is smaller than the opening area of ​​each of the plurality of openings 21d. Therefore, when the plurality of hollow fiber membranes 22 are formed from a hollow fiber membrane fabric in which the plurality of hollow fiber membranes 22 serving as weft threads are woven with warp threads, the warp threads are less likely to be pushed into the through holes 23a than when the opening area ratio between the through holes 23a and the openings 21d is the same. As a result, the hollow fiber membranes are less likely to be pushed into the through holes 23a due to the support of the warp threads.

[0093] Furthermore, in this hollow fiber membrane element 2, the opening area of ​​each of the plurality of through holes 23a is smaller than the opening area of ​​each of the plurality of openings 21d. Therefore, the through holes 23a can be made smaller than when the opening area ratio between the through holes 23a and the openings 21d is the same. This allows for a larger area of ​​the warp yarns in contact with the space-forming member 23 when the plurality of hollow fiber membranes 22 are formed from a hollow fiber membrane fabric in which the plurality of hollow fiber membranes 22 serving as weft yarns are woven with the warp yarns. This means that more warp yarns can be disposed between the plurality of hollow fiber membranes 22 and the space-forming member 23. This also creates a larger space between the plurality of hollow fiber membranes 22 and the space-forming member 23, thereby increasing the space through which the liquid L flows between the plurality of hollow fiber membranes 22 and the liquid distribution pipe 21.

[0094] Furthermore, in this hollow fiber membrane element 2, the number of the through holes 23a is greater than the number of the openings 21d, so that many of the through holes 23a can be disposed at positions farther away from the openings 21d, thereby further reducing the pressure loss of the liquid L.

[0095] Furthermore, in this hollow fiber membrane element 2, the space-forming member 23 is formed in a mesh shape, so that the through-holes 23a can be arranged regularly, which allows the liquid L to be guided from the plurality of through-holes 23a to the openings 21d over a wide area, thereby further reducing the pressure loss of the liquid L.

[0096] Furthermore, in this hollow fiber membrane element 2, the space-forming member 23 has a plurality of first linear portions 231a extending in the first direction d1 and a plurality of second linear portions 231b extending in the second direction d2 and connected to the plurality of first linear portions 231a, and a plurality of through holes 23a are formed between the plurality of first linear portions 231a and the plurality of second linear portions 231b. Therefore, the through holes 23a can be arranged regularly. This allows the liquid L to be guided from the plurality of through holes 23a to the openings 21d over a wide area, further reducing the pressure loss of the liquid L.

[0097] Furthermore, in this hollow fiber membrane element 2, the space-forming member 23 is configured such that the multiple connection portions 23e between the multiple first linear portions 231a and the multiple second linear portions 231b are thicker than the linear portions 23f between the multiple connection portions 23e, so that the surface 23c of the space-forming member 23 facing the liquid circulation pipe 21 can easily be formed into an uneven shape.

[0098] In the hollow fiber membrane module 1 according to this embodiment, the hollow portion 21 a of the liquid circulation pipe 21 is blocked by the baffle 26 in the element intermediate portion 2 c between the first fixing portion 24 and the second fixing portion 25 in the extending direction D. Therefore, when the liquid L is supplied from the liquid supply port 3 a, the liquid L is supplied from one side of the liquid circulation pipe 21 (the second end liquid circulation pipe opening 21 c side) to the hollow portion 21 a of the liquid circulation pipe 21, exits the liquid circulation pipe 21 from the opening 21 d on the upstream side of the baffle 26 (the second end liquid circulation pipe opening 21 c side) and comes into contact with the plurality of hollow fiber membranes 22, returns to the hollow portion 21 a of the liquid circulation pipe 21 from the opening 21 d on the downstream side of the baffle (the first end liquid circulation pipe opening 21 b side), and is discharged from the other side of the liquid circulation pipe 21 (the first end liquid circulation pipe opening 21 b side) to the liquid discharge port 3 b.

[0099] Here, when the liquid L returns from the opening 21d to the hollow portion 21a of the liquid distribution pipe 21 downstream of the baffle (the side of the first end liquid distribution pipe opening 21b), it tries to push the plurality of hollow fiber membranes 22 into the opening 21d. However, a space forming member 23 having a plurality of through holes 23a formed therein is disposed between the liquid distribution pipe 21 and the plurality of hollow fiber membranes 22, and the space forming member 23 forms a communication space 23b between the liquid distribution pipe 21 and at least one of the plurality of openings 21d that is located between the baffle 26 and the first fixing portion 24 in the extension direction D and the plurality of through holes 23a. Therefore, even if a hollow fiber membrane 22 is pushed into the through hole 23a located above the opening 21d, i.e., even if the hollow fiber membrane 22 is clogged in the through hole 23a located at a position overlapping the opening 21d, the liquid L is guided through the communication space 23b from the through hole 23a located away from the opening 21d to the opening 21d. This allows the pressure loss of the liquid L to be reduced.

[0100] In the first degassing method according to the present embodiment, the hollow fiber membrane module 1 in which the hollow fiber membrane elements 2 described above are accommodated in the housing 3 is used, and the liquid L is degassed by suctioning the first gas port 3c and the second gas port 3d and supplying the liquid L to the liquid supply port 3a, thereby reducing the pressure loss of the liquid L.

[0101] In the second degassing method according to the present embodiment, a hollow fiber membrane module 1 in which the above-described hollow fiber membrane elements 2 are accommodated in a housing 3 is used, and the liquid L is degassed by supplying a sweep gas to the first gas port 3c and supplying the liquid L to the liquid supply port 3a, thereby reducing the pressure loss of the liquid L.

[0102] In the gas addition method according to the present embodiment, a hollow fiber membrane module 1 in which the above-described hollow fiber membrane elements 2 are accommodated in a housing 3 is used, and gas is supplied to the first gas port 3 c and the second gas port 3 d to pressurize the hollow portions 22 a of the plurality of hollow fiber membranes 22, and liquid L is supplied to the liquid supply port 3 a, thereby adding gas to the liquid L, and therefore the pressure loss of the liquid L can be reduced.

[0103] By degassing seawater as the liquid L, the carbon dioxide concentration in the seawater can be reduced, and thus the carbon dioxide concentration in the atmosphere can be reduced.

[0104] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments.

[0105] For example, an inter-membrane baffle that closes the space between the plurality of hollow fiber membranes may be provided in the middle part of the element between the first fixing part and the second fixing part in the extension direction.

[0106] Fig. 14 is a schematic cross-sectional view of a hollow fiber membrane module of a modified example. The hollow fiber membrane module 1A shown in Fig. 14 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 a hollow fiber membrane element 2A corresponding to the hollow fiber membrane element 2 of the above embodiment is provided with an inter-membrane baffle 27 that closes the space between the plurality of hollow fiber membranes 22 in the element intermediate portion 2c between the first fixing portion 24 and the second fixing portion 25 in the extension direction D.

[0107] In the hollow fiber membrane module 1A, when liquid L is supplied from the liquid supply port 3 a, the liquid L is supplied from one side of the liquid circulation pipe 21 (the side of the second end liquid circulation pipe opening 21 c) to the hollow portion 21 a of the liquid circulation pipe 21, exits the liquid circulation pipe from opening 21 d on the upstream side of the baffle 26 (the side of the second end liquid circulation pipe opening 21 c), comes into contact with the plurality of hollow fiber membranes, passes through the gaps between the plurality of hollow fiber membranes 22 and the cylindrical portion 31, comes into contact with the plurality of hollow fiber membranes 22, returns to the hollow portion 21 a of the liquid circulation pipe 21 from opening 21 d on the downstream side of the baffle 26 (the side of the first end liquid circulation pipe opening 21 b), and is discharged from the other side of the liquid circulation pipe 21 (the side of the first end liquid circulation pipe opening 21 b) to the liquid discharge port 3 b.

[0108] In this way, the hollow fiber membrane module 1A (hollow fiber membrane element 2A) is provided with an inter-membrane baffle 27 that closes the space between the plurality of hollow fiber membranes 22 in the element intermediate section 2c, so that the liquid L that has flowed out of the liquid circulation pipe 21 from the opening 21d on the upstream side of the baffle 26 (the second end liquid circulation pipe opening 21c side) can pass through the plurality of hollow fiber membranes 22, and then pass through the plurality of hollow fiber membranes 22 again to be returned to the hollow section 21a of the liquid circulation pipe 21 from the opening 21d on the downstream side of the baffle 26 (the first end liquid circulation pipe opening 21b side). This makes it possible to lengthen the contact time between the liquid L and the plurality of hollow fiber membranes 22.

[0109] Furthermore, in the above embodiment, the housing is described as having two gas ports, a first gas port and a second gas port. However, the housing may have only one gas port as long as it can degas or add gas to the liquid. For example, in the first degassing method of the above embodiment, the housing may have one gas port, and the liquid can be degassed by suctioning the gas port. Furthermore, in the gas addition method of the above embodiment, the housing may have one gas port, and the gas can be added to the liquid by supplying gas to the gas port.

[0110] DESCRIPTION OF SYMBOLS 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, 2c...element middle portion, 3...housing, 3a...liquid supply port, 3b...liquid discharge port, 3c...first gas port, 3d...second gas port, 21...liquid circulation pipe, 21a...hollow portion, 21b...first end liquid circulation pipe opening, 21c...second end liquid circulation pipe opening, 21d...opening, 21e...end, 21f...end, 211...first pipe portion, 212...second pipe portion, 22...hollow fiber membrane, 22a...hollow portion, 22b... First end hollow fiber membrane opening, 22c... Second end hollow fiber membrane opening, 23... Space forming member, 23a... Through hole, 23b... Communication space, 23c... Surface, 23d... Surface, 23e... Connection portion, 23f... Linear portion, 24... First fixing part, 25... Second fixing part, 26... Baffle, 27... Intermembrane baffle, 31... Cylindrical 32...first lid part, 32a...first communication space, 33...second lid part, 33a...second communication space, 231a...first linear part, 231b...second linear part, D...extension direction, D1...first extension direction, D2...second extension direction, d1...first direction, d2...second direction, L...liquid, R1...internal region, R2...external region.

Claims

a first fixing part located at one end of the liquid circulation pipe in the extending direction and fixing the plurality of hollow fiber membranes to the liquid circulation pipe so as to seal the gap between the liquid circulation pipe and the plurality of hollow fiber membranes and leave the hollow portion of the liquid circulation pipe and the hollow portions of the plurality of hollow fiber membranes open; a second fixing part located at the other end of the liquid circulation pipe in the extending direction and fixing the plurality of hollow fiber membranes to the liquid circulation pipe so as to seal the gap between the liquid circulation pipe and the plurality of hollow fiber membranes and leave the hollow portion of the liquid circulation pipe and the hollow portions of the plurality of hollow fiber membranes open; a baffle located at an intermediate part of the element between the first fixing part and the second fixing part in the extending direction and fixing the hollow portion of the liquid circulation pipe; and a space forming member located between the liquid circulation pipe and the plurality of hollow fiber membranes and having a plurality of through holes formed therein. the space forming member forms a communication space between the space forming member and the liquid circulation pipe, which communicates the plurality of through holes with at least one opening of the plurality of openings that is located between the baffle and the first fixing part in the extension direction.

2. A hollow fiber membrane element as described in claim 1, wherein the liquid circulation pipe has a first pipe section located between the first fixed section and the baffle in the extension direction, and a second pipe section located between the second fixed section and the baffle in the extension direction, the space-forming member covers at least the first pipe section, and the communicating space connects the openings of the plurality of openings that are covered by the space-forming member with the plurality of through-holes.

3. The hollow fiber membrane element according to claim 1, wherein the space-forming member extends from the first fixing portion to the second fixing portion, and the first fixing portion and the second fixing portion fix the space-forming member to the liquid distribution pipe.

4. The hollow fiber membrane element according to claim 1, wherein the surface of the space-forming member facing the liquid distribution pipe is formed unevenly.

5. The hollow fiber membrane element according to claim 1, wherein the opening area of ​​each of the plurality of through holes is smaller than the opening area of ​​each of the plurality of openings.

6. The hollow fiber membrane element according to claim 1, wherein the number of said plurality of through holes is greater than the number of said plurality of openings.

7. The hollow fiber membrane element according to claim 1, wherein the space-forming member is formed in a mesh shape.

8. A hollow fiber membrane element as described in claim 1, wherein the space-forming member has a plurality of first linear portions extending in a first direction and a plurality of second linear portions extending in a second direction intersecting the first direction and connected to the plurality of first linear portions, and the plurality of through-holes are formed between the plurality of first linear portions and the plurality of second linear portions.

9. The hollow fiber membrane element according to claim 8, wherein the space-forming member is configured such that the multiple connection portions between the multiple first linear portions and the multiple second linear portions are thicker than the linear portions between the multiple connection portions.

10. The hollow fiber membrane element according to claim 1, further comprising an inter-membrane baffle that closes the space between the plurality of hollow fiber membranes in an intermediate portion of the element between the first fixing portion and the second fixing portion in the extension direction.

11. A hollow fiber membrane module comprising: a hollow fiber membrane element according to any one of claims 1 to 10; a housing accommodating the hollow fiber membrane element; a liquid supply port for supplying liquid from one side of the liquid circulation pipe to the hollow portion of the liquid circulation pipe; a liquid discharge port for discharging liquid in the hollow portion of the liquid circulation pipe from the other side of the liquid circulation pipe; and a gas port communicating with the hollow portions of the plurality of hollow fiber membranes, wherein the region within the housing is partitioned by the plurality of hollow fiber membranes into an internal region including the hollow portions of the plurality of hollow fiber membranes and an external region including the hollow portion of the liquid circulation pipe.

12. A degassing method for degassing a liquid using the hollow fiber membrane module according to claim 11, comprising suctioning the gas port of the hollow fiber membrane module and supplying a liquid to the liquid supply port of the hollow fiber membrane module.

13. A degassing method for degassing a liquid using the hollow fiber membrane module according to claim 11, comprising supplying a sweep gas to the gas port of the hollow fiber membrane module and supplying a liquid to the liquid supply port of the hollow fiber membrane module.

14. A gas addition method for adding a gas to a liquid using the hollow fiber membrane module according to claim 11, comprising supplying a gas to the gas port of the hollow fiber membrane module to pressurize the hollow portions of the plurality of hollow fiber membranes, and supplying a liquid to the liquid supply port of the hollow fiber membrane module.

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