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

Abstract

The hollow fiber membrane element comprises a liquid distribution pipe, a plurality of hollow fiber membranes, a first fixing part located at an end in a first extension direction and fixing the plurality of hollow fiber membranes to the liquid distribution pipe, and a second fixing part located at an end in a second extension direction (the other of the extension directions) and fixing the plurality of hollow fiber membranes to the liquid distribution pipe, and an O-ring groove for fitting an O-ring is formed on the outer peripheral surface of each of the first fixing part and the second fixing part. The hollow fiber membrane module comprises a hollow fiber membrane element, a housing that accommodates the hollow fiber membrane element, a first O-ring fitted into the O-ring groove formed in the first fixing part and pressed against the first fixing part and the housing, and a second O-ring fitted into the O-ring groove formed in the second fixing part and pressed against the second fixing part and the housing.

Description

[Technical Field]

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

[0002] Patent Document 1 describes a hollow fiber membrane module that degasses a liquid using hollow fiber membranes. This hollow fiber membrane module is configured by housing one or more hollow fiber membrane elements (cartridges) housed in a housing (container). The hollow fiber membrane element includes a cylindrical housing, a liquid distribution pipe (central tube) housed in the housing, a plurality of hollow fiber membranes (membrane mats) arranged around the liquid distribution pipe, and fixing portions (potting) filled between the housing and the liquid distribution pipe at both ends of the plurality of hollow fiber membranes. The outer peripheral surface of the housing of the hollow fiber membrane element is formed with a groove into which an O-ring is fitted to seal the gap with the housing of the hollow fiber membrane module. In the hollow fiber membrane module, the gap between the housing of the hollow fiber membrane module and the hollow fiber membrane element is sealed by an O-ring fitted in a groove formed in the outer peripheral surface of the housing of the hollow fiber membrane element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6002719 Summary of the Invention [Problem to be solved by the invention]

[0004] In the hollow fiber membrane module described in Patent Document 1, the housing of the hollow fiber membrane element is disposed on the inner periphery of the housing of the hollow fiber membrane module, making it difficult to increase the area for arranging multiple hollow fiber membranes, and therefore also difficult to increase the membrane area in the hollow fiber membrane module.

[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 increase the membrane area. [Means for solving the problem]

[0006] [1] A hollow fiber membrane element according to the present disclosure comprises: a liquid distribution pipe having a plurality of openings; a plurality of hollow fiber membranes arranged around the liquid distribution pipe so as to extend along the liquid distribution pipe and cover the plurality of openings; a first fixing part located at an end of the liquid distribution pipe in a first extension direction, which is one of the directions in which the liquid distribution pipe extends, and fixing 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 to leave the hollow portion of the liquid distribution pipe and the hollow portions of the plurality of hollow fiber membranes open; and a second fixing part located at an end of the liquid distribution pipe in a second extension direction, which is the other direction in the extension direction, and fixing 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 to leave the hollow portion of the liquid distribution pipe and the hollow portions of the plurality of hollow fiber membranes open, and O-ring grooves for fitting O-rings are formed on the outer peripheral surfaces of each of the first fixing part and the second fixing part.

[0007] In this hollow fiber membrane element, the plurality of hollow fiber membranes are arranged around the liquid distribution pipe so as to cover the plurality of openings. The first and second fixing parts secure the plurality of hollow fiber membranes to the liquid distribution pipe at the ends in the first and second extension directions, sealing the gap between the liquid distribution pipe and the plurality of hollow fiber membranes and leaving the hollow portions of the liquid distribution pipe and the plurality of hollow fiber membranes open. Therefore, the liquid can be degassed by reducing the pressure in the hollow portions of the plurality of hollow fiber membranes and supplying liquid to the outside of the plurality of hollow fiber membranes.

[0008] An O-ring groove for fitting an O-ring is formed on the outer peripheral surface of each of the first and second fixing parts. Therefore, in a hollow fiber membrane module in which this hollow fiber membrane element is housed in a housing, the O-rings fitted into the O-ring grooves formed on the outer peripheral surfaces of each of the first and second fixing parts can seal the gap between the housing of the hollow fiber membrane module and the hollow fiber membrane element. Therefore, compared to the hollow fiber membrane module described in Patent Document 1, in which the housing of the hollow fiber membrane element is arranged on the inner peripheral side of the housing of the hollow fiber membrane module, the area in which multiple hollow fiber membranes can be arranged can be increased. This allows for an increased membrane area.

[0009] [2] In the hollow fiber membrane element described in [1], each of the first and second fixing parts may have a fixing part that fixes the plurality of hollow fiber membranes to the liquid distribution pipe and a groove forming part with an O-ring groove formed on its outer circumferential surface. In this hollow fiber membrane element, each of the first and second fixing parts can be manufactured separately into a fixing part that fixes the plurality of hollow fiber membranes to the liquid distribution pipe and a groove forming part with an O-ring groove formed on its outer circumferential surface. This makes it possible to easily manufacture each of the first and second fixing parts.

[0010] [3] In the hollow fiber membrane element described in [1] or [2], the hollow portion of the liquid distribution pipe may be continuous from its tip in the first extension direction to its tip in the second extension direction. In this hollow fiber membrane element, the hollow portion of the liquid distribution pipe is continuous from its tip in the first extension direction to its tip in the second extension direction, allowing liquid to flow from one end of the hollow portion of the liquid distribution pipe to the other end. Therefore, for example, in a hollow fiber membrane module in which hollow fiber membrane elements are housed in a housing, by closing the hollow portion of the liquid distribution pipe at one end and supplying liquid to the hollow portion of the liquid distribution pipe from the other end, the liquid can be discharged from the openings to the outside of the liquid distribution pipe over the entire extension direction of the liquid distribution pipe, brought into contact with multiple hollow fiber membranes, and then discharged from the hollow fiber membrane module.

[0011] [4] The hollow fiber membrane element according to [1] or [2] may further comprise a baffle that blocks the hollow portion of the liquid distribution pipe at an intermediate portion of the element between the first and second fixing portions in the extension direction. In this hollow fiber membrane element, the hollow portion of the liquid distribution pipe is blocked by the baffle at the intermediate portion of the element. This prevents liquid from passing through the hollow portion of the liquid distribution pipe at the intermediate portion of the element. Therefore, for example, in a hollow fiber membrane module in which hollow fiber membrane elements are housed in a housing, by supplying liquid to the hollow portion of the liquid distribution pipe from one end, the liquid can be discharged from the opening on the upstream side of the baffle to the outside of the liquid distribution pipe and brought into contact with the multiple hollow fiber membranes, and then returned to the hollow portion of the liquid distribution pipe from the opening on the downstream side of the baffle and discharged from the hollow fiber membrane module.

[0012] [5] The hollow fiber membrane element described in [4] may further include an inter-membrane baffle that closes the space between the hollow fiber membranes in the middle of the element. This hollow fiber membrane element includes an inter-membrane baffle that closes the space between the hollow fiber membranes in the middle 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 middle 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 contact the hollow fiber membranes for a longer period of time.

[0013] [6] A hollow fiber membrane module according to the present disclosure comprises: a hollow fiber membrane element according to any one of [1] to [5]; a housing for accommodating the hollow fiber membrane element; a liquid supply port for supplying liquid to a hollow portion of the liquid circulation pipe; a liquid discharge port for discharging liquid discharged from the liquid circulation pipe; a gas port communicating with the hollow portions of a plurality of hollow fiber membranes; a first O-ring fitted into an O-ring groove formed in the first fixing part and pressed against the first fixing part and the housing; and a second O-ring fitted into an O-ring groove formed in the second fixing part and pressed against the second fixing part and the housing.

[0014] In this hollow fiber membrane module, a first O-ring and a second O-ring are fitted into O-ring grooves formed on the outer peripheral surfaces of the first and second fixing parts, respectively, and these first O-rings and second O-rings are pressed against the first and second fixing parts and the housing, so that these first O-rings and second O-rings can seal the gap between the housing of the hollow fiber membrane module and the hollow fiber membrane element. Therefore, compared to the hollow fiber membrane module described in Patent Document 1, where the housing of the hollow fiber membrane element is arranged on the inner periphery of the housing of the hollow fiber membrane module, the area in which multiple hollow fiber membranes can be arranged can be increased. This allows for an increased membrane area.

[0015] [7] In the hollow fiber membrane module described in [6], the housing may have a cylindrical portion formed in a cylindrical shape and accommodating the hollow fiber membrane element, the first O-ring being pressed against the first fixing portion and the cylindrical portion, and the second O-ring being pressed against the second fixing portion and the cylindrical portion. In this hollow fiber membrane module, the hollow fiber membrane element is accommodated in the cylindrical portion formed in a cylindrical shape, and the first O-ring and the second O-ring are pressed against the first fixing portion and the second fixing portion and the cylindrical portion, so sealing by the first O-ring and the second O-ring can be easily performed. Moreover, sealing between the cylindrical portion and the hollow fiber membrane element is achieved by the elastic force of the first O-ring and the second O-ring, so the hollow fiber membrane element can be easily attached and detached from the cylindrical portion. This makes it easy to replace the hollow fiber membrane element.

[0016] [8] The hollow fiber membrane module described in [7] may further comprise: a first end member having a first extension portion accommodated in the cylindrical portion and extending in the extension direction, and a first flange portion extending from the first extension portion toward the cylindrical portion and having an O-ring groove formed on its outer peripheral surface for fitting an O-ring, with at least a portion thereof being located on the side of the hollow fiber membrane element in the first extension direction; a second end member having a second extension portion accommodated in the cylindrical portion and extending in the extension direction, and a second flange portion extending from the second extension portion toward the cylindrical portion and having an O-ring groove formed on its outer peripheral surface for fitting an O-ring, with at least a portion thereof being located on the side of the hollow fiber membrane element in the second extension direction; a third O-ring fitted in the O-ring groove formed in the first end member and pressed against the first end member and the cylindrical portion; and a fourth O-ring fitted in an O-ring groove formed in the second end member and pressed against the second end member and the cylindrical portion.

[0017] This hollow fiber membrane module includes a first end member at least partially disposed in the first extension direction relative to the hollow fiber membrane elements, and a third O-ring is fitted into an O-ring groove formed on the outer peripheral surface of the first flange portion of the first end member, and the third O-ring is pressed against the first end member and the cylindrical portion. Therefore, the third O-ring can seal the gap between the first end member and the cylindrical portion, and a space communicating with the hollow portions of the hollow fiber membranes can be formed between the hollow fiber membrane element and the first flange portion. The module also includes a second end member at least partially disposed in the second extension direction relative to the hollow fiber membrane elements, and a fourth O-ring is fitted into an O-ring groove formed on the outer peripheral surface of the second flange portion of the second end member, and the fourth O-ring is pressed against the second end member and the cylindrical portion. Therefore, the fourth O-ring can seal the gap between the second end member and the cylindrical portion, and a space communicating with the hollow portions of the hollow fiber membranes can be formed between the hollow fiber membrane element and the second flange portion. As a result, for example, by suctioning these spaces, the hollow portions of the hollow fiber membranes can be suctioned, and the liquid supplied from the liquid supply port can be degassed. Furthermore, by supplying a sweep gas to one of these spaces, the sweep gas can be supplied to the hollow portions of the hollow fiber membranes, and the liquid supplied from the liquid supply port can be degassed. Furthermore, by supplying a gas to these spaces, the gas can be supplied to the hollow portions of the hollow fiber membranes, and the gas can be added to the liquid supplied from the liquid supply port.

[0018] [9] The hollow fiber membrane module described in [8] may further include a first snap ring that engages the first flange portion from the first extension direction side and a second snap ring that engages the second flange portion from the second extension direction side, and the inner circumferential surface of the cylindrical portion may be formed with a first snap ring groove into which the first snap ring is fitted and a second snap ring groove into which the second snap ring is fitted. In this hollow fiber membrane module, the hollow fiber membrane element can be detached from the cylindrical portion by removing the first snap ring or the second snap ring from the first snap ring groove or the second snap ring groove and extracting the hollow fiber membrane element from the cylindrical portion. Meanwhile, the hollow fiber membrane element can be attached to the cylindrical portion by inserting the hollow fiber membrane element into the cylindrical portion and fitting the first snap ring or the second snap ring into the first snap ring groove or the second snap ring groove. This facilitates attachment and detachment of the hollow fiber membrane element to and from the cylindrical portion. This facilitates replacement of the hollow fiber membrane element.

[0019]

[10] In the hollow fiber membrane module described in [8] or [9], the hollow portion of the liquid circulation pipe is connected from its tip in the first extension direction to its tip in the second extension direction and is closed at its end in the first extension direction by a first end member, a communication space connected to the hollow portions of the plurality of hollow fiber membranes is formed between at least one of the first flange portion and the second flange portion and the hollow fiber membrane element, a liquid supply port is formed in the second extension portion and communicates with the end in the second extension direction of the hollow portion of the liquid circulation pipe, a liquid discharge port is formed in the cylindrical portion at a position between the first fixing portion and the second fixing portion in the extension direction, and a gas port may be formed in the cylindrical portion at a position adjacent to the communication space.

[0020] In this hollow fiber membrane module, the hollow portion of the liquid distribution pipe is connected from its tip in the first extension direction to its tip in the second extension direction and is closed at its end in the first extension direction by the first extension portion. A liquid supply port is formed in the second extension portion and is connected to the end of the hollow portion of the liquid distribution pipe in the second extension direction. A liquid discharge port is formed in the cylindrical portion at a position between the first and second fixed portions in the extension direction. Therefore, by supplying liquid to the liquid supply port, the liquid can be discharged from the opening to the outside of the liquid distribution pipe throughout the entire extension direction of the liquid distribution pipe, contacted with the plurality of hollow fiber membranes, and then discharged from the liquid discharge port. A communication space communicating with the hollow portions of the plurality of hollow fiber membranes is formed between at least one of the first flange portion and the second flange portion and the hollow fiber membrane element. A gas port is formed in the cylindrical portion adjacent to the communication space. Therefore, for example, by suctioning the gas port, the liquid supplied from the liquid supply port can be degassed. Furthermore, by supplying a sweep gas to the gas port, the liquid supplied from the liquid supply port can be degassed, and by supplying a gas to the gas port, gas can be added to the liquid supplied from the liquid supply port.

[0021]

[11] In the hollow fiber membrane module described in [8] or [9], the hollow portion of the liquid circulation pipe is blocked by a baffle in the element intermediate portion between the first fixing portion and the second fixing portion in the extension direction, and a communication space communicating with the hollow portions of the plurality of hollow fiber membranes is formed between at least one of the first flange portion and the second flange portion and the hollow fiber membrane element, the liquid supply port is formed in the second extension portion and communicates with the end of the hollow portion of the liquid circulation pipe in the second extension direction, the liquid discharge port is formed in the first extension portion and communicates with the end of the hollow portion of the liquid circulation pipe in the first extension direction, and the gas port may be formed in the cylindrical portion at a position adjacent to the communication space.

[0022] In this hollow fiber membrane module, a liquid supply port is formed in the second extension portion and is connected to an end of the hollow portion of the liquid distribution pipe in the second extension direction, and a liquid discharge port is formed in the first extension portion and is connected to an end of the hollow portion of the liquid distribution pipe in the first extension direction. Therefore, by supplying liquid to the liquid supply port, the liquid can be discharged from the opening on the upstream side of the baffle to the outside of the liquid distribution pipe and contacted with the plurality of hollow fiber membranes, and then returned to the hollow portion of the liquid distribution pipe through the opening on the downstream side of the baffle and discharged from the liquid discharge port. A communication space communicating with the hollow portions of the plurality of hollow fiber membranes is formed between at least one of the first flange portion and the second flange portion and the hollow fiber membrane element, and a gas port is formed in the cylindrical portion adjacent to the communication space. Therefore, for example, by suctioning the gas port, the liquid supplied through the liquid supply port can be degassed. Furthermore, by supplying a sweep gas to the gas port, the liquid supplied through the liquid supply port can be degassed. Furthermore, by supplying gas to the gas port, the gas can be added to the liquid supplied from the liquid supply port.

[0023]

[12] A degassing method according to the present disclosure is a method for degassing a liquid using the hollow fiber membrane module described in any one of [6] to

[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. In this degassing method, a hollow fiber membrane module having the above-mentioned hollow fiber membrane element housed in a housing is used, and the liquid is degassed by suctioning the gas port and supplying a liquid to the liquid supply port, thereby increasing the membrane area and improving degassing performance.

[0024]

[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 any one of [6] to

[11] , which includes supplying a sweep gas to a gas port of the hollow fiber membrane module and supplying a liquid 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 housed in a housing, and degasses the liquid by supplying a sweep gas to the gas port and supplying a liquid to the liquid supply port, thereby increasing the membrane area and improving degassing performance.

[0025]

[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 any one of [6] to

[11] , which includes supplying a gas to a 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 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 housed in a housing, and adds a gas to a 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 increasing the membrane area and improving gas addition performance. [Effects of the Invention]

[0026] According to the present disclosure, the membrane area can be increased. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic cross-sectional view of a hollow fiber membrane element according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II shown in FIG. [Figure 3] FIG. 2 is a schematic cross-sectional view showing a part of the hollow fiber membrane element shown in FIG. [Figure 4] FIG. 2 is a schematic cross-sectional view showing a part of the hollow fiber membrane element shown in FIG. [Figure 5] 1 is a schematic cross-sectional view of a hollow fiber membrane module according to a first embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a part of the hollow fiber membrane module shown in FIG. [Figure 7] FIG. 6 is a schematic cross-sectional view showing a part of the hollow fiber membrane module shown in FIG. [Figure 8] FIG. 4 is a schematic cross-sectional view of a hollow fiber membrane element according to a second embodiment. [Figure 9] FIG. 4 is a schematic cross-sectional view of a hollow fiber membrane module according to a second embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view showing a part of the hollow fiber membrane module shown in FIG. [Figure 11] FIG. 10 is a schematic cross-sectional view of a hollow fiber membrane module according to a third embodiment. [Figure 12] FIG. 10 is a schematic cross-sectional view of a hollow fiber membrane module according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0028] 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.

[0029] [Hollow fiber membrane element according to the first embodiment] FIG. 1 is a schematic cross-sectional view of a hollow fiber membrane element according to a first 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 the first embodiment is used to degas a liquid L or add a gas to the liquid L, and is incorporated into a hollow fiber membrane module, which will be described later. The liquid L is not particularly limited, but examples thereof include seawater, drinking water, pure water, ultrapure water, and other water; aqueous solutions containing ammonium sulfate, surfactants, and the like; organic solvents such as alcohols and hydrocarbons; and ionic liquids. The gas added to the liquid L is not particularly limited, but examples thereof include carbon dioxide (CO2), nitrogen (N2), and the like. The hollow fiber membrane element 2 comprises a liquid distribution pipe 21, a plurality of hollow fiber membranes 22, a first fixing part 24, and a second fixing part 25.

[0030] The liquid distribution pipe 21 is a cylindrical member extending in the extension direction D to support a plurality of hollow fiber membranes 22. Of the two directions of the extension direction 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 side of the first extension direction D1 is referred to as a first element end 2a, and the end of the hollow fiber membrane element 2 on the side of the second extension direction D2 is referred to as a second element end 2b. The liquid distribution pipe 21 has enough rigidity to support a plurality of hollow fiber membranes 22.

[0031] The hollow portion 21a of the liquid circulation pipe 21 is a flow path (internal 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 21a of the liquid circulation pipe 21 at the second element end 2b, i.e., the opening on the second extension direction D2 side of the hollow portion 21a of the liquid circulation pipe 21, is referred to as the second end liquid circulation pipe opening 21c. The hollow portion 21a of the liquid circulation pipe 21 is continuous from its end in the first extension direction D1 to its end in the second extension direction D2. In other words, no member such as a baffle that prevents the movement of the liquid L in the extension direction D is provided in the hollow portion 21a of the liquid circulation pipe 21.

[0032] A plurality of openings 21d are formed in the liquid circulation pipe 21. The plurality of openings 21d are holes for circulating the liquid L 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.

[0033] The plurality of hollow fiber membranes 22 extend along the liquid distribution pipe 21 and are arranged around the liquid distribution pipe 21 so as to cover the plurality of openings 21d. The plurality of hollow fiber membranes 22 extending along the liquid distribution 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.

[0034] 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 21d. 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.

[0035] 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 over the entire area in the extending 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 extending direction D1 to the end of the hollow fiber membrane element 2 in the second extending direction D2. The hollow portions 22a of the plurality of hollow fiber membranes 22 are open in the first extending direction D1 and the second extending direction D2. 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 extending direction D1 side, are referred to as first end hollow fiber membrane openings 22b. The openings of the hollow portions 22a of the hollow fiber membranes 22 at the second element end 2b, that is, the openings of the hollow portions 22a of the hollow fiber membranes 22 on the second extending direction D2 side, are referred to as second end hollow fiber membrane openings 22c.

[0036] The hollow fiber membrane 22 is a hollow fiber 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 resins such as polypropylene, polyethylene, and polymethylpentene; silicone resins such as polydimethylsiloxane and its copolymers; and fluorine-based resins such as PTFE and vinylidene fluoride. Examples of the shape (sidewall shape) of the hollow fiber membrane 22 include a porous membrane, a microporous membrane, and a homogeneous membrane (non-porous membrane) that does not have porosity. Examples of the form of the hollow fiber membrane 22 include a symmetric membrane (homogeneous membrane) in which the entire membrane has a homogeneous chemical or physical structure, and an asymmetric membrane (heterogeneous membrane) 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.

[0037] There are no particular limitations on the outer diameter of the hollow fiber membrane 22. 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.

[0038] As shown in FIGS. 1 to 3 , 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 distribution pipe 21 so as to seal the gap between the liquid distribution pipe 21 and the plurality of hollow fiber membranes 22 and leave the hollow portion 21a of the liquid distribution pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. That is, the first fixing portion 24 fixes the end of the plurality of hollow fiber membranes 22 on the side of the first extending direction D1 to the liquid distribution pipe 21. The first fixing portion 24 also seals the gap between the liquid distribution 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 distribution pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22, leaving the hollow portion 21a of the liquid distribution pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. The first fixing portion 24 is formed, for example, from a resin.

[0039] The first fixed portion 24 is formed in a substantially cylindrical shape. A first O-ring groove 24b for fitting an O-ring is formed in the outer peripheral surface 24a of the first fixed portion 24. The first O-ring groove 24b is formed in a ring shape and extends over the entire circumferential direction of the first fixed portion 24. The number of first O-ring grooves 24b is not particularly limited, but may be, for example, one. In this embodiment, the number of first O-ring grooves 24b is one.

[0040] As shown in FIG. 3, the first fixing portion 24 may be composed of a fixing portion 24c that fixes the plurality of hollow fiber membranes 22 to the liquid distribution pipe 21, and a groove forming portion 24d in which the first O-ring groove 24b is formed.

[0041] The fixing portion 24c is a portion that fixes the plurality of hollow fiber membranes 22 to the liquid distribution pipe 21 so as to seal the gap between the liquid distribution pipe 21 and the plurality of hollow fiber membranes 22 and to leave the hollow portion 21a of the liquid distribution pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. The fixing portion 24c is formed in a substantially cylindrical shape, and a recess 24e into which the groove-forming portion 24d is fitted is formed on its outer circumferential surface. The recess 24e extends over the entire circumferential area of ​​the first fixing portion 24. The fixing portion 24c can be formed of, for example, a material that easily seals the gap between the liquid distribution pipe 21 and the plurality of hollow fiber membranes 22. Examples of materials for the fixing portion 24c include epoxy resin, urethane resin, polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP).

[0042] The groove-forming portion 24d is a portion that forms the outer peripheral surface 24a of the first fixed portion 24 and the first O-ring groove 24b. The groove-forming portion 24d is formed in a substantially cylindrical shape and is fitted into the recess 24e of the fixed portion 24c. The length of the groove-forming portion 24d in the extension direction D is substantially the same as the length of the recess 24e in the extension direction D, and the groove-forming portion 24d is fitted into the recess 24e without any gaps. The groove-forming portion 24d can be formed, for example, from a material that easily forms the first O-ring groove 24b. Examples of materials for the groove-forming portion 24d include epoxy resin, urethane resin, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polyvinyl chloride, and metal.

[0043] 1, 2, and 4, 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 distribution pipe 21 so as to seal the gap between the liquid distribution pipe 21 and the plurality of hollow fiber membranes 22 and leave the hollow portion 21a of the liquid distribution pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. That is, the second fixing portion 25 fixes the end of the plurality of hollow fiber membranes 22 on the second extending direction D2 side to the liquid distribution pipe 21. The second fixing portion 25 seals the gap between the liquid distribution 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 distribution pipe 21 or the hollow portions 22a of the plurality of hollow fiber membranes 22, leaving the hollow portion 21a of the liquid distribution 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.

[0044] The second fixed portion 25 is formed in a substantially cylindrical shape. A second O-ring groove 25b for fitting an O-ring is formed in the outer peripheral surface 25a of the second fixed portion 25. The second O-ring groove 25b is formed in a ring shape and extends over the entire circumferential area of ​​the second fixed portion 25. The number of second O-ring grooves 25b is not particularly limited, but may be, for example, one. In this embodiment, the number of second O-ring grooves 25b is one.

[0045] As shown in FIG. 4, the second fixing portion 25 may be composed of a fixing portion 25c that fixes the plurality of hollow fiber membranes 22 to the liquid distribution pipe 21, and a groove forming portion 25d in which the second O-ring groove 25b is formed.

[0046] The fixing portion 25c is a portion that fixes the plurality of hollow fiber membranes 22 to the liquid distribution pipe 21 so as to seal the gap between the liquid distribution pipe 21 and the plurality of hollow fiber membranes 22 and to leave the hollow portion 21a of the liquid distribution pipe 21 and the hollow portions 22a of the plurality of hollow fiber membranes 22 open. The fixing portion 25c is formed in a substantially cylindrical shape, and a recess 25e into which the groove-forming portion 25d is fitted is formed on its outer circumferential surface. The recess 25e extends over the entire circumferential area of ​​the second fixing portion 25. The fixing portion 25c can be formed of, for example, a material that easily seals the gap between the liquid distribution pipe 21 and the plurality of hollow fiber membranes 22. Examples of materials for the fixing portion 25c include epoxy resin, urethane resin, polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP).

[0047] The groove-forming portion 25d is a portion that forms the outer circumferential surface 25a of the second fixed portion 25 and the second O-ring groove 25b. The groove-forming portion 25d is formed in a substantially cylindrical shape and is fitted into the recess 25e of the fixed portion 25c. The length of the groove-forming portion 25d in the extension direction D is substantially the same as the length of the recess 25e in the extension direction D, and the groove-forming portion 25d is fitted into the recess 25e without any gaps. The groove-forming portion 25d can be made of, for example, a material that can easily form the second O-ring groove 25b. Examples of materials for the groove-forming portion 25d include epoxy resin, urethane resin, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polyvinyl chloride, and metal.

[0048] [Hollow fiber membrane module according to the first embodiment] Fig. 5 is a schematic cross-sectional view of a hollow fiber membrane module according to the first embodiment. Fig. 6 is a schematic cross-sectional view showing a portion of the hollow fiber membrane module shown in Fig. 5. Fig. 7 is a schematic cross-sectional view showing a portion of the hollow fiber membrane module shown in Fig. 5. As shown in Figs. 5 to 7, the hollow fiber membrane module 1 according to the first embodiment is a module for degassing a liquid L or adding a gas to the liquid L. The hollow fiber membrane module 1 comprises the hollow fiber membrane element 2 according to the first embodiment described above, a housing 3, a first O-ring 4, a second O-ring 5, a first end member 6, a third O-ring 7, a second end member 8, a fourth O-ring 9, a first snap ring 10, and a second snap ring 11.

[0049] The housing 3 accommodates the hollow fiber membrane element 2 so that a space is formed between the hollow fiber membrane element 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.

[0050] The housing 3 is formed in a cylindrical shape and includes a cylindrical portion 31 that houses the hollow fiber membrane element 2. 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 coincides with the extending direction of the cylindrical portion 31. 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, and therefore the extending direction of the cylindrical portion 31 is also referred to as the extending direction D. Both ends of the cylindrical portion 31 in the extending direction D are open and not closed. The cylindrical portion 31 is formed to be longer than the hollow fiber membrane element 2 in the first extending direction D1, and is formed to be longer than the hollow fiber membrane element 2 in the second extending direction D2.

[0051] The first O-ring 4 is fitted into a first O-ring groove 24b formed in the first fixing portion 24 of the hollow fiber membrane element 2. When a plurality of first O-ring grooves 24b are formed in the first fixing portion 24, a first O-ring 4 is fitted into each of the plurality of first O-ring grooves 24b. The first O-ring 4 is pressed against the first fixing portion 24 and the cylindrical portion 31 (housing 3), thereby sealing the gap between the first fixing portion 24 and the cylindrical portion 31.

[0052] The second O-ring 5 is fitted into a second O-ring groove 25b formed in the second fixing portion 25 of the hollow fiber membrane element 2. When a plurality of second O-ring grooves 25b are formed in the second fixing portion 25, a second O-ring 5 is fitted into each of the plurality of second O-ring grooves 25b. The second O-ring 5 is pressed against the second fixing portion 25 and the cylindrical portion 31 (housing 3), thereby sealing the gap between the second fixing portion 25 and the cylindrical portion 31.

[0053] Therefore, the area inside the housing 3 is divided into an inner area R1 and an outer area R2 by the plurality of hollow fiber membranes 22 as a boundary. The outer area 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 area 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 area R1, which is a gas phase area, and the outer area R2, which is a liquid phase area. In other words, the inside (hollow portions 22a) of the hollow fiber membranes 22 forms the inner area R1, and the outside of the hollow fiber membranes 22 forms the outer area R2. The plurality of hollow fiber membranes 22 prevent the liquid L from permeating from the outer area R2 to the inner area R1 and allow the gas to permeate from the outer area R2 to the inner area R1.

[0054] 5 and 6, the first end member 6 is a member at least partially disposed on the first extending direction D1 side of the hollow fiber membrane element 2. The first end member 6 has a first extending portion 61 housed in the cylindrical portion 31 and extending in the extending direction D, and a first flange portion 62 extending from the first extending portion 61 toward the cylindrical portion 31.

[0055] The first extension portion 61 is inserted into the end portion 21e of the liquid circulation pipe 21 on the first extension direction D1 side. The first extension portion 61 extends from the end portion 21e of the liquid circulation pipe 21 in the first extension direction D1. The first extension portion 61 is formed in a solid shape and closes the hollow portion 21a at the end portion 21e of the liquid circulation pipe 21. That is, the hollow portion 21a of the liquid circulation pipe 21 is closed by the first extension portion 61 of the first end member 6 at the end portion on the first extension direction D1 side. Therefore, the liquid L supplied to the hollow portion 21a of the liquid circulation pipe 21 is discharged radially outward from the plurality of openings 21d formed in the liquid circulation pipe 21 without being discharged in the first extension direction D1 from the first end liquid circulation pipe opening 21b. An O-ring for closing the hollow portion 21a may be disposed between the first extension portion 61 and the liquid circulation pipe 21. This O-ring may be fitted into an O-ring groove formed on the outer circumferential surface of the first extending portion 61, for example.

[0056] The first flange portion 62 extends from the first extending portion 61 toward the cylindrical portion 31 at a position away from the hollow fiber membrane element 2 in the first extending direction D1. A first communicating space R11, through which the hollow portions 22a of the plurality of hollow fiber membranes 22 communicate with each other, is formed between the hollow fiber membrane element 2 and the first flange portion 62. The first communicating space R11 is a space adjacent to the first end hollow fiber membrane openings 22b of the plurality of hollow fiber membranes 22, and is part of the internal region R1.

[0057] The first flange portion 62 is formed in a substantially circular plate shape. A third O-ring groove 62b for fitting the third O-ring 7 is formed in an outer peripheral surface 62a of the first flange portion 62. The third O-ring groove 62b is formed in a ring shape and extends over the entire circumferential area of ​​the first flange portion 62. The number of third O-ring grooves 62b is not particularly limited, but may be, for example, one. In this embodiment, the number of third O-ring grooves 62b is one.

[0058] The third O-ring 7 is fitted into a third O-ring groove 62b formed in the first flange portion 62. If multiple third O-ring grooves 62b are formed in the first flange portion 62, a third O-ring 7 is fitted into each of the multiple third O-ring grooves 62b. The third O-ring 7 is pressed against the first flange portion 62 and the cylindrical portion 31 of the first end member 6, sealing the gap between the first flange portion 62 and the cylindrical portion 31. Therefore, the first extension direction D1 side of the first communication space R11 is closed by the first flange portion 62 and the third O-ring 7.

[0059] 5 and 7, the second end member 8 is a member at least partially disposed on the second extending direction D2 side of the hollow fiber membrane element 2. The second end member 8 has a second extending portion 81 housed in the cylindrical portion 31 and extending in the extending direction D, and a second flange portion 82 extending from the second extending portion 81 toward the cylindrical portion 31.

[0060] The second extension portion 81 is inserted into the end portion 21f of the liquid circulation pipe 21 on the second extension direction D2 side. The second extension portion 81 extends from the end portion 21f of the liquid circulation pipe 21 in the second extension direction D2. The second extension portion 81 is formed in a pipe shape, and a liquid supply port A is formed in its hollow portion. The liquid supply port A is a port for supplying the liquid L from the second end liquid circulation pipe opening 21c to the hollow portion 21a of the liquid circulation pipe 21, and is in communication with the hollow portion 21a of the liquid circulation pipe 21.

[0061] The second flange portion 82 extends from the second extending portion 81 toward the cylindrical portion 31 at a position away from the hollow fiber membrane element 2 in the second extending direction D2. A second communicating space R12, through which the hollow portions 22a of the plurality of hollow fiber membranes 22 communicate with each other, is formed between the hollow fiber membrane element 2 and the second flange portion 82. The second communicating space R12 is a space adjacent to the second end hollow fiber membrane openings 22c of the plurality of hollow fiber membranes 22, and is part of the internal region R1.

[0062] The second flange portion 82 is formed in a substantially circular plate shape. A fourth O-ring groove 82b for fitting the fourth O-ring 9 is formed in the outer peripheral surface 82a of the second flange portion 82. The fourth O-ring groove 82b is formed in a ring shape and extends over the entire circumferential area of ​​the second flange portion 82. The number of fourth O-ring grooves 82b is not particularly limited, but may be, for example, one. In this embodiment, the number of fourth O-ring grooves 82b is one.

[0063] The fourth O-ring 9 is fitted into a fourth O-ring groove 82b formed in the second flange portion 82. If multiple fourth O-ring grooves 82b are formed in the second flange portion 82, a fourth O-ring 9 is fitted into each of the multiple fourth O-ring grooves 82b. The fourth O-ring 9 is pressed against the second flange portion 82 and the cylindrical portion 31 of the second end member 8, sealing the gap between the second flange portion 82 and the cylindrical portion 31. Therefore, the second extension direction D2 side of the second communication space R12 is closed by the second flange portion 82 and the fourth O-ring 9.

[0064] 5 and 6, the first snap ring 10 is a member for retaining the first flange portion 62 from the first extending direction D1 side. A snap ring is also called a retaining ring, a C-ring, or the like. The first snap ring 10 is fitted into a first snap ring groove 35 formed on the inner circumferential surface of the cylindrical portion 31. By fitting the first snap ring 10 into the first snap ring groove 35, the hollow fiber membrane element 2, the first end member 6, and the second end member 8 are positioned in the first extending direction D1. In other words, the first snap ring groove 35 is formed at a position where the first snap ring 10 can position the hollow fiber membrane element 2, the first end member 6, and the second end member 8 in the first extending direction D1.

[0065] 5 and 7, the second snap ring 11 is a member for latching the second flange portion 82 from the second extending direction D2 side. The second snap ring 11 is fitted into a second snap ring groove 36 formed on the inner circumferential surface of the cylindrical portion 31. By fitting the second snap ring 11 into the second snap ring groove 36, the hollow fiber membrane element 2, the first end member 6, and the second end member 8 are positioned in the second extending direction D2. In other words, the second snap ring groove 36 is formed at a position where the hollow fiber membrane element 2, the first end member 6, and the second end member 8 can be positioned in the second extending direction D2 by the second snap ring 11.

[0066] 5 to 7, the housing 3 has a liquid discharge section 32 that forms the liquid discharge port B, a first suction section 33a that forms the first gas port C1, and a second suction section 33b that forms the second gas port C2. The liquid discharge port B is a port for discharging the liquid L from the hollow section 21a of the liquid circulation pipe 21. The first gas port C1 and the second gas port C2 are ports that communicate with the hollow sections 22a of the plurality of hollow fiber membranes 22.

[0067] The liquid discharge port B is a port that penetrates the housing 3. The liquid discharge port B is formed in the cylindrical portion 31 at a position between the first fixed portion 24 and the second fixed portion 25 in the extension direction D, and is in communication with the external region R2 adjacent to the cylindrical portion 31.

[0068] The first gas port C1 is a port that penetrates the housing 3. The first gas port C1 is formed in the cylindrical portion 31 at a position adjacent to the first communication space R11 and is in communication with the first communication space R11. The second gas port C2 is a port that penetrates the housing 3. The second gas port C2 is formed in the cylindrical portion 31 at a position adjacent to the second communication space R12 and is in communication with the second communication space R12.

[0069] [First degassing method according to the first embodiment: vacuum mode] Next, a description will be given of the first degassing method according to the first embodiment. The first degassing method according to the first embodiment is a method for degassing the liquid L using the hollow fiber membrane module 1 in a vacuum mode.

[0070] In this first degassing method, the first gas port C1 and the second gas port C2 of the hollow fiber membrane module 1 are suctioned, and liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1. Suction of the first gas port C1 and the second gas port C2 can be performed, for example, by connecting a suction device (not shown) such as a vacuum pump to the first suction section 33a and the second suction section 33b via piping or the like and operating this suction device. Supply of liquid L to the liquid supply port A can be performed, for example, by connecting a liquid supply device (not shown) such as a liquid feed pump that sends out liquid L via piping or the like to the second extension section 81 of the second end member 8 and operating this liquid supply device.

[0071] When the first gas port C1 and the second gas port C2 are suctioned, the internal region R1 connected to the first gas port C1 and the second gas port C2 is suctioned, and the hollow portions 22a of the hollow fiber membranes 22 are depressurized. When the liquid L is supplied to the liquid supply port A, the liquid L is supplied from the second-end liquid circulation pipe opening 21c to the hollow portion 21a of the liquid circulation pipe 21, discharged from the openings 21d of the liquid circulation pipe 21 into the space outside the liquid circulation pipe 21, and contacts the hollow fiber membranes 22. Because the hollow portions 22a of the hollow fiber membranes 22 are depressurized, dissolved gas in the liquid L and gases such as bubbles contained in the liquid L permeate the hollow fiber membranes 22, pass through the hollow portions 22a of the hollow fiber membranes 22, the first communicating space R11, and the second communicating space R12, and are discharged from the first gas port C1 and the second gas port C2. This degassing the liquid L. The degassed liquid L passes through the space between the hollow fiber membrane element 2 and the cylindrical portion 31 and is discharged from a liquid discharge port B formed in the liquid discharge portion 32 .

[0072] [Second degassing method according to the first embodiment: sweep mode] Next, a description will be given of the second degassing method according to the first embodiment. The second degassing method according to the first embodiment is a method for degassing the liquid L using the hollow fiber membrane module 1 in a sweep mode.

[0073] In this second degassing method, a sweep gas is supplied to the first gas port C1 of the hollow fiber membrane module 1, and liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1. Examples of the sweep gas include air (dry air), nitrogen gas, and argon gas. The sweep gas may be supplied to the second gas port C2 instead of the first gas port C1. The supply of the sweep gas to the first gas port C1 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 C1 via piping or the like and operating this gas supply device. The supply of liquid L to the liquid supply port A 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 second extension portion 81 of the second end member 8 and operating this liquid supply device.

[0074] When a sweep gas is supplied to the first gas port C1, the sweep gas passes through the first communication space R11, the hollow portions 22a of the plurality of hollow fiber membranes 22, and the second communication space R12, flows from the first gas port C1 to the second gas port C2, and is discharged from the second gas port C2. When a liquid L is supplied to the liquid supply port A, the liquid L is supplied from the second-end liquid circulation pipe opening 21c to the hollow portion 21a of the liquid circulation pipe 21, and is discharged from the plurality of openings 21d of the liquid circulation pipe 21 to the space outside the liquid circulation pipe 21, where it comes into contact with the plurality of hollow fiber membranes 22. At this time, the hollow portions 22a of the plurality of hollow fiber membranes 22 are swept by the sweep gas, so that gases such as dissolved gas in the liquid L and gas bubbles contained in the liquid L permeate the plurality of hollow fiber membranes 22, pass through the hollow portions 22a of the plurality of hollow fiber membranes 22 and the second communication space R12, and are discharged from the second gas port C2 together with the sweep gas. This degasses the liquid L. The degassed liquid L passes through the space between the hollow fiber membrane element 2 and the cylindrical portion 31 and is discharged from the liquid discharge port B formed in the liquid discharge section 32.

[0075] [Third degassing method according to the first embodiment: combo mode] Next, a description will be given of the third degassing method according to the first embodiment. The third degassing method according to the first embodiment is a method of degassing the liquid L using the hollow fiber membrane module 1 in a combo mode that combines the sweep mode and the vacuum mode.

[0076] In this third degassing method, a sweep gas is supplied to the first gas port C1 of the hollow fiber membrane module 1, and the second gas port C2 of the hollow fiber membrane module 1 is suctioned, while the liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1. Alternatively, a sweep gas may be supplied to the second gas port C2 and the first gas port C1 is suctioned. The supply of the sweep gas to the first gas port C1 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 C1 via piping or the like and operating this gas supply device. The suction of the second gas port C2 can be performed, for example, by connecting a suction device (not shown) such as a vacuum pump to the second gas port C2 via piping or the like and operating this suction device. The supply of the liquid L to the liquid supply port A 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 second extension portion 81 of the second end member 8 and operating this liquid supply device.

[0077] When a sweep gas is supplied to the first gas port C1, the sweep gas flows from the first gas port C1 to the second gas port C2 through the first communication space R11, the hollow portions 22a of the hollow fiber membranes 22, and the second communication space R12. When suction is applied to the second gas port C2, the sweep gas supplied from the first gas port C1 is sucked toward the second gas port C2 and discharged from the second gas port C2. Furthermore, when liquid L is supplied to the liquid supply port A, the liquid L is supplied from the second-end liquid circulation pipe opening 21c to the hollow portion 21a of the liquid circulation pipe 21, and is discharged from the multiple openings 21d of the liquid circulation pipe 21 to the space outside the liquid circulation pipe 21, where it comes into contact with the multiple hollow fiber membranes 22. At this time, the hollow portions 22a of the hollow fiber membranes 22 are swept by the sweep gas, and the sweep gas is drawn toward the second gas port C2, causing dissolved gas in the liquid L and gases such as bubbles contained in the liquid L to permeate the hollow fiber membranes 22, pass through the hollow portions 22a of the hollow fiber membranes 22 and the second communication space R12, and be discharged from the second gas port C2 together with the sweep gas. This degasses the liquid L. The degassed liquid L passes through the space between the hollow fiber membrane element 2 and the cylindrical portion 31 and is discharged from the liquid discharge port B formed in the liquid discharge section 32.

[0078] [Gas Addition Method According to First Embodiment] Next, a description will be given of the gas addition method according to the first embodiment. The gas addition method according to the first embodiment is a method of adding a gas to a liquid L using a hollow fiber membrane module 1.

[0079] In this gas addition method, gas is supplied to the first gas port C1 and the second gas port C2 of the hollow fiber membrane module 1, and liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1. The supply of gas to the first gas port C1 and the second gas port C2 can be achieved, for example, by connecting a gas supply device (not shown) such as a compressor to the first gas port C1 and the second gas port C2 via piping or the like and operating this gas supply device. The supply of liquid L to the liquid supply port A can be achieved, 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 A and operating this liquid supply device.

[0080] When gas is supplied to the first gas port C1 and the second gas port C2, the gas is supplied to the hollow portions 22a of the plurality of hollow fiber membranes 22 connected to the first gas port C1 and the second gas port C2, 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 C1 and the second gas port C2 so that the gas supplied to the first gas port C1 and the second gas port C2 pressurizes the hollow portions 22a of the plurality of hollow fiber membranes 22. Furthermore, when liquid L is supplied to the liquid supply port A, the liquid L is supplied from the second-end liquid circulation pipe opening 21c to the hollow portion 21a of the liquid circulation pipe 21, and is discharged from the plurality of openings 21d of the liquid circulation pipe 21 to the space outside the liquid circulation pipe 21 and comes into contact with the plurality of hollow fiber membranes 22. At this time, the hollow portions 22a of the plurality of hollow fiber membranes 22 are pressurized by the gas supplied from the first gas port C1 and the second gas port C2, and this gas permeates the plurality of hollow fiber membranes 22 and comes into contact with the liquid L. This causes the gas to be added to the liquid L. The liquid L to which the gas has been added passes through the space between the hollow fiber membrane element 2 and the cylindrical portion 31 and is discharged from the liquid discharge port B formed in the liquid discharge portion 32.

[0081] As described above, in the hollow fiber membrane element 2 according to the first embodiment, the plurality of hollow fiber membranes 22 are arranged around the liquid circulation pipe 21 so as to cover the plurality of openings 21d. Furthermore, the first fixing part 24 and the second fixing part 25 fix the plurality of hollow fiber membranes 22 to the liquid circulation pipe 21 at the ends in the first extension direction D1 and the second extension direction D2 so as to seal the gap between the liquid circulation pipe 21 and the plurality of hollow fiber membranes 22 and to leave the hollow part 21a of the liquid circulation pipe 21 and the hollow parts 22a of the plurality of hollow fiber membranes 22 open. Therefore, by reducing the pressure in the hollow parts 22a of the plurality of hollow fiber membranes 22 and supplying the liquid L to the outside of the plurality of hollow fiber membranes 22, the liquid L can be degassed.

[0082] A first O-ring groove 24b for fitting an O-ring is formed on the outer peripheral surface 24a of the first fixing part 24, and a second O-ring groove 25b for fitting an O-ring is formed on the outer peripheral surface 25a of the second fixing part 25. Therefore, in a hollow fiber membrane module 1 in which this hollow fiber membrane element 2 is housed in a housing 3, the gap between the housing 3 of the hollow fiber membrane module 1 and the hollow fiber membrane element 2 can be sealed by the first O-ring 4 fitted in the first O-ring groove 24b and the second O-ring 5 fitted in the second O-ring groove 25b. Therefore, compared to the hollow fiber membrane module described in Patent Document 1, in which the housing of the hollow fiber membrane element is arranged on the inner peripheral side of the housing of the hollow fiber membrane module, the area in which multiple hollow fiber membranes 22 can be arranged can be increased. This allows for an increased membrane area.

[0083] Furthermore, in this hollow fiber membrane element 2, the first fixing part 24 can be manufactured separately into a fixing part 24c that fixes the plurality of hollow fiber membranes 22 to the liquid distribution pipe 21, and a groove forming part 24d in which a first O-ring groove 24b is formed in the outer peripheral surface 24a. Furthermore, the second fixing part 25 can be manufactured separately into a fixing part 25c that fixes the plurality of hollow fiber membranes 22 to the liquid distribution pipe 21, and a groove forming part 25d in which a second O-ring groove 25b is formed in the outer peripheral surface 25a. Therefore, each of the first fixing part 24 and the second fixing part 25 can be manufactured easily.

[0084] Furthermore, in this hollow fiber membrane element 2, the hollow portion 21a of the liquid circulation pipe 21 is connected from its tip in the first extending direction D1 to its tip in the second extending direction D2, so that the liquid L can be circulated from one end to the other end of the hollow portion 21a of the liquid circulation pipe 21. Therefore, for example, in a hollow fiber membrane module 1 in which the hollow fiber membrane element 2 is housed in a housing 3, by closing the hollow portion 21a of the liquid circulation pipe 21 at one end and supplying the liquid L to the hollow portion 21a of the liquid circulation pipe 21 from the other end, the liquid L can be discharged from the openings 21d to the outside of the liquid circulation pipe 21 over the entire area in the extending direction D of the liquid circulation pipe 21, brought into contact with the plurality of hollow fiber membranes 22, and then discharged from the hollow fiber membrane module 1.

[0085] In the hollow fiber membrane module 1 according to the first embodiment, a first O-ring 4 is fitted into a first O-ring groove 24b formed in the outer peripheral surface 24a of the first fixing portion 24, and a second O-ring 5 is fitted into a second O-ring groove 25b formed in the outer peripheral surface 25a of the second fixing portion 25. The first O-ring 4 and the second O-ring 5 are pressed against the first fixing portion 24 and the second fixing portion 25 and the housing 3. This allows the first O-ring 4 and the second O-ring 5 to seal the gap between the housing 3 of the hollow fiber membrane module 1 and the hollow fiber membrane element 2. This allows for a larger area for arranging multiple hollow fiber membranes 22 than in the hollow fiber membrane module described in Patent Document 1, where the housing of the hollow fiber membrane element is arranged on the inner periphery of the housing of the hollow fiber membrane module. This allows for an increased membrane area.

[0086] Furthermore, in this hollow fiber membrane module 1, the hollow fiber membrane element 2 is housed in a cylindrical portion 31 formed in a cylindrical shape, and the first O-ring 4 and the second O-ring 5 are pressed against the first fixing portion 24 and the second fixing portion 25 and the cylindrical portion 31, so that sealing by the first O-ring 4 and the second O-ring 5 can be easily performed. Moreover, since sealing between the cylindrical portion 31 and the hollow fiber membrane element 2 is performed by the elastic force of the first O-ring 4 and the second O-ring 5, the hollow fiber membrane element 2 can be easily attached to and detached from the cylindrical portion 31. This makes it easy to replace the hollow fiber membrane element 2.

[0087] The hollow fiber membrane module 1 also includes a first end member 6, at least a portion of which is disposed closer to the hollow fiber membrane elements 2 in the first extending direction D1, and a third O-ring 7 is fitted into a third O-ring groove 62b formed on the outer circumferential surface 62a of the first flange portion 62 of the first end member 6, and the third O-ring 7 is pressed against the first end member 6 and the cylindrical portion 31. Therefore, the third O-ring 7 can seal the gap between the first end member 6 and the cylindrical portion 31, and can form a first communication space R11 between the hollow fiber membrane elements 2 and the first flange portion 62, which communicates with the hollow portions 22a of the plurality of hollow fiber membranes 22. The hollow fiber membrane module 1 also includes a second end member 8, at least a portion of which is disposed closer to the hollow fiber membrane elements 2 in the second extending direction D2, and a fourth O-ring 9 is fitted into a fourth O-ring groove 82b formed on the outer circumferential surface 82a of the second flange portion 82 of the second end member 8, and the fourth O-ring 9 is pressed against the second end member 8 and the cylindrical portion 31. Therefore, the fourth O-ring 9 can seal the gap between the second end member 8 and the cylindrical portion 31, and can also form a second communication space R12 between the hollow fiber membrane element 2 and the second flange portion, which is in communication with the hollow portions 22a of the plurality of hollow fiber membranes 22. As a result, for example, by suctioning the first communication space R11 and the second communication space R12, the hollow portions 22a of the plurality of hollow fiber membranes 22 can be suctioned, and the liquid L supplied from the liquid supply port A can be degassed. Furthermore, by supplying a sweep gas to the first communication space R11 or the second communication space R12, the sweep gas can be supplied to the hollow portions 22a of the plurality of hollow fiber membranes 22, and the liquid L supplied from the liquid supply port A can be degassed. Furthermore, by supplying a gas to the first communication space R11 and the second communication space R12, the gas can be supplied to the hollow portions 22a of the plurality of hollow fiber membranes 22, and the gas can be added to the liquid L supplied from the liquid supply port A.

[0088] Furthermore, in this hollow fiber membrane module 1, the hollow fiber membrane element 2 can be detached from the cylindrical portion 31 by removing the first snap ring 10 or the second snap ring 11 from the first snap ring groove 35 or the second snap ring groove 36 and extracting the hollow fiber membrane element 2 from the cylindrical portion 31. On the other hand, the hollow fiber membrane element 2 can be attached to the cylindrical portion 31 by inserting the hollow fiber membrane element 2 into the cylindrical portion 31 and fitting the first snap ring 10 or the second snap ring 11 into the first snap ring groove 35 or the second snap ring groove 36. This makes it easy to attach and detach the hollow fiber membrane element 2 to and from the cylindrical portion 31. This allows for easy replacement of the hollow fiber membrane element 2.

[0089] Furthermore, in this hollow fiber membrane module 1, the hollow portion 21a of the liquid circulation pipe 21 is in communication from its tip in the first extension direction D1 to its tip in the second extension direction D2, and is closed at its end in the first extension direction D1 by the first extension portion 61, the liquid supply port A is formed in the second extension portion 81 and is in communication with the end of the hollow portion 21a of the liquid circulation pipe 21 in the second extension direction D2, and the liquid discharge port B is formed in the cylindrical portion 31 at a position between the first fixed portion 24 and the second fixed portion 25 in the extension direction D. Therefore, by supplying liquid L to the liquid supply port A, the liquid L can be discharged from the openings 21d to the outside of the liquid circulation pipe 21 over the entire area of ​​the liquid circulation pipe 21 in the extension direction D, brought into contact with the plurality of hollow fiber membranes 22, and then discharged from the liquid discharge port B. A first communication space R11 communicating with the hollow portions 22a of the plurality of hollow fiber membranes 22 is formed between the first flange portion 62 and the hollow fiber membrane element 2, and a second communication space R12 communicating with the hollow portions 22a of the plurality of hollow fiber membranes 22 is formed between the second flange portion 82 and the hollow fiber membrane element 2. A first gas port C1 is formed in the cylindrical portion 31 at a position adjacent to the first communication space R11, and a second gas port C2 is formed in the cylindrical portion 31 at a position adjacent to the second communication space R12. Therefore, for example, by suctioning the first gas port C1 and the second gas port C2, the liquid L supplied from the liquid supply port A can be degassed. Furthermore, by supplying a sweep gas to the first gas port C1 or the second gas port C2, the liquid L supplied from the liquid supply port A can be degassed. Furthermore, by supplying a gas to the first gas port C1 and the second gas port C2, gas can be added to the liquid L supplied from the liquid supply port A.

[0090] In the first degassing method according to the first embodiment, a hollow fiber membrane module 1 in which the above-mentioned hollow fiber membrane element 2 is accommodated in a housing 3 is used to degas the liquid L by suctioning the first gas port C1 and the second gas port C2 and supplying the liquid L to the liquid supply port A, and therefore the degassing performance can be improved by increasing the membrane area.

[0091] In the second degassing method according to the first embodiment, a hollow fiber membrane module 1 in which the above-described hollow fiber membrane element 2 is accommodated in a housing 3 is used, and a sweep gas is supplied to the first gas port C1 and liquid L is supplied to the liquid supply port A to degas the liquid L, thereby increasing the membrane area and improving the degassing performance.

[0092] In the gas addition method according to the first 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 C1 and the second gas port C2 to pressurize the hollow portions 22a of the plurality of hollow fiber membranes 22, and liquid L is supplied to the liquid supply port A to add gas to the liquid L, thereby increasing the membrane area and improving gas addition performance.

[0093] By degassing seawater as the liquid L, the carbon dioxide concentration in the seawater can be reduced, and this can reduce the carbon dioxide concentration in the atmosphere.

[0094] [Hollow fiber membrane element according to the second embodiment] Next, a hollow fiber membrane element according to a second embodiment will be described. The hollow fiber membrane element according to the second embodiment is basically the same as the hollow fiber membrane element 2 according to the first embodiment, but differs from the hollow fiber membrane element 2 according to the first embodiment in that baffles are provided in the liquid distribution pipes. Therefore, in the following description, only the differences from the hollow fiber membrane element 2 according to the first embodiment will be described, and descriptions similar to those of the hollow fiber membrane element 2 according to the first embodiment will be omitted.

[0095] Fig. 8 is a schematic cross-sectional view of a hollow fiber membrane element according to the second embodiment. As shown in Fig. 8, the hollow fiber membrane element 2A according to the second embodiment includes a liquid distribution pipe 21, a plurality of hollow fiber membranes 22, a first fixing part 24, a second fixing part 25, a baffle 26, and an inter-membrane baffle 27.

[0096] 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 is provided in the hollow portion 21a of the liquid circulation pipe 21 in the element intermediate portion 2c between the first fixed portion 24 and the second fixed portion 25 in the extension direction D. The baffle 26 blocks the hollow portion 21a of the liquid circulation pipe 21 in the element intermediate portion 2c. 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 the 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 the second pipe portion 212.

[0097] The inter-membrane baffle 27 prevents the liquid L from flowing in the extending direction D through the spaces between the plurality of hollow fiber membranes 22. The inter-membrane baffle 27 is provided in the element intermediate section 2c between the first fixing part 24 and the second fixing part 25 in the extending direction D, in the spaces between the plurality of hollow fiber membranes 22. The inter-membrane baffle 27 blocks the spaces between the plurality of hollow fiber membranes 22 in the element intermediate section 2c. The inter-membrane baffle 27 may block all of the spaces between the plurality of hollow fiber membranes 22 in the element intermediate section 2c, or may block only some of the spaces between the plurality of hollow fiber membranes 22.

[0098] [Hollow fiber membrane module according to the second embodiment] Next, a hollow fiber membrane module according to a second embodiment will be described. The hollow fiber membrane module according to the second embodiment is basically the same as the hollow fiber membrane module 1 according to the first embodiment, but differs from the hollow fiber membrane module 1 according to the first embodiment in that a hollow fiber membrane element 2A according to the second embodiment is used instead of the hollow fiber membrane element 2 according to the first embodiment. Therefore, in the following description, only the differences from the hollow fiber membrane module 1 according to the first embodiment will be described, and descriptions similar to those of the hollow fiber membrane module 1 according to the first embodiment will be omitted.

[0099] Fig. 9 is a schematic cross-sectional view of a hollow fiber membrane module according to a second embodiment. Fig. 10 is a schematic cross-sectional view showing a portion of the hollow fiber membrane module shown in Fig. 9. As shown in Figs. 9 and 10, a hollow fiber membrane module 1A according to the second embodiment includes a hollow fiber membrane element 2A according to the second embodiment described above, a housing 3A, a first O-ring 4, a second O-ring 5, a first end member 6A, a third O-ring 7A, a second end member 8, a fourth O-ring 9, a first snap ring 10, and a second snap ring 11.

[0100] The housing 3A has a cylindrical portion 31A formed in a cylindrical shape. The cylindrical portion 31A is basically the same as the housing 3 of the hollow fiber membrane module 1 according to the first embodiment, but differs from the housing 3 of the hollow fiber membrane module 1 according to the first embodiment in that it does not have a liquid discharge portion that forms the liquid discharge port B.

[0101] The first end member 6A has a configuration similar to that of the second end member 8. At least a portion of the first end member 6A is disposed on the first extending direction D1 side of the hollow fiber membrane element 2A. The first end member 6A has a first extending portion 61A housed in the cylindrical portion 31A and extending in the extending direction D, and a first flange portion 62A extending from the first extending portion 61A toward the cylindrical portion 31A.

[0102] The first extension portion 61A is inserted into the end portion 21e of the liquid circulation pipe 21 on the first extension direction D1 side. The first extension portion 61A extends from the end portion 21e of the liquid circulation pipe 21 in the first extension direction D1. The first extension portion 61A is formed in a pipe shape, and a liquid discharge port B is formed in its hollow portion. The liquid discharge port B is a port for discharging the liquid L from the first end liquid circulation pipe opening 21b, and is in communication with the hollow portion 21a of the liquid circulation pipe 21.

[0103] The first flange portion 62A extends from the first extending portion 61A toward the cylindrical portion 31A at a position away from the hollow fiber membrane element 2A in the first extending direction D1. A first communicating space R11, through which the hollow portions 22a of the plurality of hollow fiber membranes 22 communicate with each other, is formed between the hollow fiber membrane element 2A and the first flange portion 62A. The first communicating space R11 is a space adjacent to the first end hollow fiber membrane openings 22b of the plurality of hollow fiber membranes 22, and is part of the internal region R1.

[0104] The first flange portion 62A is formed in a substantially circular plate shape. A third O-ring groove 62Ab for fitting the third O-ring 7A is formed in an outer peripheral surface 62Aa of the first flange portion 62A. The third O-ring groove 62Ab is formed in a ring shape and extends over the entire circumferential direction of the first flange portion 62A.

[0105] The third O-ring 7A is fitted into a third O-ring groove 62Ab formed in the first flange portion 62A. The third O-ring 7A is pressed against the first flange portion 62A and the cylindrical portion 31A of the first end member 6A, sealing the gap between the first flange portion 62A and the cylindrical portion 31A. Therefore, the first extension direction D1 side of the first communication space R11 is closed by the first flange portion 62A and the third O-ring 7A.

[0106] The first snap ring 10 is fitted into a first snap ring groove 35 formed on the inner peripheral surface of the cylindrical portion 31A and hooks onto the first flange portion 62A from the first extending direction D1 side. By being fitted into the first snap ring groove 35, the first snap ring 10 positions the hollow fiber membrane element 2A, the first end member 6A, and the second end member 8 in the first extending direction D1.

[0107] The housing 3A has a first suction portion 33Aa that forms the first gas port C1 and a second suction portion 33Ab that forms the second gas port C2. The first gas port C1 and the second gas port C2 are ports that communicate with the hollow portions 22a of the multiple hollow fiber membranes 22.

[0108] The first gas port C1 is a port that penetrates the housing 3A. The first gas port C1 is formed in the cylindrical portion 31A at a position adjacent to the first communication space R11 and is in communication with the first communication space R11. The second gas port C2 is a port that penetrates the housing 3A. The second gas port C2 is formed in the cylindrical portion 31A at a position adjacent to the second communication space R12 and is in communication with the second communication space R12.

[0109] [First degassing method according to the second embodiment: vacuum mode] Next, a description will be given of the first degassing method according to the second embodiment. The first degassing method according to the second embodiment is a method for degassing the liquid L in a vacuum mode using the hollow fiber membrane module 1A.

[0110] In this first degassing method, the first gas port C1 and the second gas port C2 of the hollow fiber membrane module 1A are suctioned, and the liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1A.

[0111] When the first gas port C1 and the second gas port C2 are suctioned, the internal region R1 connected to the first gas port C1 and the second gas port C2 is suctioned, and the hollow portion 22a of the plurality of hollow fiber membranes 22 is decompressed. When the liquid L is supplied to the liquid supply port A, the liquid L is supplied to the hollow portion 21a of the liquid circulation pipe 21 from the second end liquid circulation pipe opening 21c. Thereafter, the liquid L exits the liquid flow pipe 21 from the opening 21d of the second pipe section 212 located on the upstream side of the baffle 26 (the side of the second end liquid flow pipe opening 21c), passes through the plurality of hollow fiber membranes 22 while coming into contact with them, passes through the gap between the inter-membrane baffle 27 and the cylindrical section 31A, passes through the plurality of hollow fiber membranes 22 while coming into contact with them again, and returns to the hollow section 21a of the liquid flow pipe 21 from the opening 21d of the first pipe section 211 located on the downstream side of the baffle 26 (the side of the first end liquid flow pipe opening 21b). At this time, because the hollow portions 22a of the plurality of hollow fiber membranes 22 are in a decompressed state, gases such as dissolved gas in the liquid L and gas bubbles contained in the liquid L permeate the plurality of hollow fiber membranes 22, pass through the hollow portions 22a of the plurality of hollow fiber membranes 22, the first communication space R11, and the second communication space R12, and are discharged from the first gas port C1 and the second gas port C2. This degasses the liquid L. Thereafter, the liquid L is discharged from the liquid discharge port B.

[0112] [Second degassing method according to the second embodiment: sweep mode] Next, a description will be given of a second degassing method according to the second embodiment. The second degassing method according to the second embodiment is a method for degassing the liquid L in a sweep mode using the hollow fiber membrane module 1A.

[0113] In this second degassing method, a sweep gas is supplied to the first gas port C1 of the hollow fiber membrane module 1A, and a liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1A. The sweep gas may be supplied to the second gas port C2 instead of the first gas port C1.

[0114] When a sweep gas is supplied to the first gas port C1, the sweep gas passes through the first communication space R11, the hollow portion 22a of the hollow fiber membranes 22, and the second communication space R12, flows from the first gas port C1 to the second gas port C2, and is discharged from the second gas port C2. When a liquid L is supplied to the liquid supply port A, the liquid L is supplied from the second-end liquid distribution pipe opening 21c to the hollow portion 21a of the liquid distribution pipe 21. The liquid L then exits the liquid distribution pipe 21 through the opening 21d of the second pipe section 212, passes through the hollow fiber membranes 22 while coming into contact with them, passes through the gap between the inter-membrane baffle 27 and the cylindrical section 31A, passes through the hollow fiber membranes 22 while coming into contact with them again, and returns to the hollow portion 21a of the liquid distribution pipe 21 through the opening 21d of the first pipe section 211. At this time, the hollow portions 22a of the plurality of hollow fiber membranes 22 are swept by the sweep gas, so that gases dissolved in the liquid L and gases such as bubbles contained in the liquid L permeate the plurality of hollow fiber membranes 22, pass through the hollow portions 22a of the plurality of hollow fiber membranes 22 and the second communication space R12, and are discharged from the second gas port C2 together with the sweep gas. This degasses the liquid L. Thereafter, the liquid L is discharged from the liquid discharge port B.

[0115] [Third degassing method according to the second embodiment: combo mode] Next, a description will be given of a third degassing method according to the second embodiment. The third degassing method according to the second embodiment is a method for degassing the liquid L in a combo mode using the hollow fiber membrane module 1A.

[0116] In this third degassing method, a sweep gas is supplied to the first gas port C1 of the hollow fiber membrane module 1A, and the second gas port C2 of the hollow fiber membrane module 1A is suctioned, while the liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1A. Alternatively, the sweep gas may be supplied to the second gas port C2 and the first gas port C1 may be suctioned.

[0117] When a sweep gas is supplied to the first gas port C1, the sweep gas flows from the first gas port C1 to the second gas port C2 through the first communication space R11, the hollow portion 22a of the plurality of hollow fiber membranes 22, and the second communication space R12. When the second gas port C2 is suctioned, the sweep gas supplied from the first gas port C1 is sucked toward the second gas port C2 and discharged from the second gas port C2. Furthermore, when liquid L is supplied to the liquid supply port A, the liquid L is supplied from the second end liquid circulation pipe opening 21c to the hollow portion 21a of the liquid circulation pipe 21. The liquid L then exits the liquid distribution pipe 21 through the opening 21d of the second pipe section 212, passes through the hollow fiber membranes 22 while coming into contact with them, passes through the gap between the inter-membrane baffle 27 and the cylindrical section 31A, passes through the hollow fiber membranes 22 while coming into contact with them again, and returns to the hollow section 21a of the liquid distribution pipe 21 through the opening 21d of the first pipe section 211. At this time, the hollow sections 22a of the hollow fiber membranes 22 are swept by the sweep gas, and the sweep gas is drawn toward the second gas port C2. As a result, dissolved gas in the liquid L and gases contained in the liquid L, such as air bubbles, permeate the hollow fiber membranes 22, pass through the hollow sections 22a of the hollow fiber membranes 22 and the second communication space R12, and are discharged from the second gas port C2 together with the sweep gas. This degassing of the liquid L. Thereafter, the liquid L is discharged from the liquid discharge port B.

[0118] [Gas Addition Method According to Second Embodiment] Next, a description will be given of a gas addition method according to the second embodiment. The gas addition method according to the second embodiment is a method for adding a gas to a liquid L using a hollow fiber membrane module 1A.

[0119] In this gas addition method, gas is supplied to the first gas port C1 and the second gas port C2 of the hollow fiber membrane module 1A, and liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1A.

[0120] When gas is supplied to the first gas port C1 and the second gas port C2, the gas is supplied to the hollow portions 22a of the plurality of hollow fiber membranes 22 connected to the first gas port C1 and the second gas port C2, 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 C1 and the second gas port C2 so that the gas supplied to the first gas port C1 and the second gas port C2 pressurizes the hollow portions 22a of the plurality of hollow fiber membranes 22. Furthermore, when liquid L is supplied to the liquid supply port A, the liquid L is supplied to the hollow portion 21a of the liquid distribution pipe 21 from the second end liquid distribution pipe opening 21c. The liquid L then exits the liquid distribution pipe 21 from the opening 21d of the second pipe section 212, passes through the hollow fiber membranes 22 while coming into contact with them, passes through the gap between the inter-membrane baffle 27 and the cylindrical section 31A, passes through the hollow fiber membranes 22 while coming into contact with them again, and returns to the hollow section 21a of the liquid distribution pipe 21 from the opening 21d of the first pipe section 211. At this time, the hollow sections 22a of the hollow fiber membranes 22 are pressurized by the gas supplied from the first gas port C1 and the second gas port C2, so the gas permeates the hollow fiber membranes 22 and comes into contact with the liquid L. As a result, the gas is added to the liquid L. The liquid L to which the gas has been added is discharged from the liquid discharge port B.

[0121] As described above, in the hollow fiber membrane element 2A according to the second embodiment, the hollow portion 21a of the liquid circulation pipe 21 is blocked by the baffle 26 at the element intermediate portion 2c. Therefore, the liquid L can be prevented from passing through the hollow portion 21a of the liquid circulation pipe 21 through the element intermediate portion 2c. For example, in a hollow fiber membrane module 1A in which the hollow fiber membrane element 2A is accommodated in a housing 3A, by supplying the liquid L from one end to the hollow portion 21a of the liquid circulation pipe 21, the liquid can be discharged from the opening 21d on the upstream side of the baffle 26 to the outside of the liquid circulation pipe 21 and brought into contact with the plurality of hollow fiber membranes 22, and then returned from the opening 21d on the downstream side of the baffle 26 to the hollow portion 21a of the liquid circulation pipe 21, and discharged from the hollow fiber membrane module 1A.

[0122] Furthermore, since this 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, the liquid L that has flowed out of the liquid distribution pipe 21 from the opening 21d on the upstream side of the baffle 26 can be made to 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 distribution pipe 21 from the opening 21d on the downstream side of the baffle 26. This allows the liquid L to be in contact with the plurality of hollow fiber membranes 22 for a longer period of time.

[0123] In the hollow fiber membrane module 1A according to the second embodiment, the liquid supply port A is formed in the second extending portion 81 and is connected to an end portion in the second extending direction D2 of the hollow portion 21a of the liquid circulation pipe 21, and the liquid discharge port B is formed in the first extending portion 61A and is connected to an end portion in the first extending direction D1 of the hollow portion 21a of the liquid circulation pipe 21. Therefore, by supplying the liquid L to the liquid supply port A, the liquid L can be discharged to the outside of the liquid circulation pipe 21 through the opening 21d on the upstream side of the baffle 26 and brought into contact with the plurality of hollow fiber membranes 22, and then returned to the hollow portion 21a of the liquid circulation pipe 21 through the opening 21d on the downstream side of the baffle 26 and discharged from the liquid discharge port B. A first communication space R11 communicating with the hollow portions 22a of the hollow fiber membranes 22 is formed between the first flange portion 62A and the hollow fiber membrane element 2A, and a second communication space R12 communicating with the hollow portions 22a of the hollow fiber membranes 22 is formed between the second flange portion 82 and the hollow fiber membrane element 2A. A first gas port C1 is formed in the cylindrical portion 31A at a position adjacent to the first communication space R11, and a second gas port C2 is formed in the cylindrical portion 31A at a position adjacent to the second communication space R12. Therefore, for example, by suctioning the first gas port C1 and the second gas port C2, the liquid L supplied from the liquid supply port A can be degassed. Furthermore, by supplying a sweep gas to the first gas port C1 or the second gas port C2, the liquid L supplied from the liquid supply port A can be degassed. Furthermore, by supplying a gas to the first gas port C1 and the second gas port C2, gas can be added to the liquid L supplied from the liquid supply port A.

[0124] [Hollow fiber membrane module according to the third embodiment] Next, a hollow fiber membrane module according to a third embodiment will be described. The hollow fiber membrane module according to the third embodiment is basically the same as the hollow fiber membrane module 1 according to the first embodiment, but differs from the hollow fiber membrane module 1 according to the first embodiment in that a plurality of hollow fiber membrane elements are housed in a housing. Therefore, in the following description, only the differences from the hollow fiber membrane module 1 according to the first embodiment will be described, and descriptions similar to those of the hollow fiber membrane module 1 according to the first embodiment will be omitted.

[0125] Fig. 11 is a schematic cross-sectional view of a hollow fiber membrane module according to the third embodiment. As shown in Fig. 11, the hollow fiber membrane module 1B according to the third embodiment is the hollow fiber membrane module 1 according to the first embodiment, except that two hollow fiber membrane elements are accommodated in the housing. The hollow fiber membrane module 1B includes two hollow fiber membrane elements 2, a housing 3B, two first O-rings 4, two second O-rings 5, a first end member 6, a third O-ring 7, a second end member 8, a fourth O-ring 9, a first snap ring 10, a second snap ring 11, and an element connecting pipe 12.

[0126] The housing 3B is formed in a cylindrical shape and has a cylindrical portion 31B that houses two hollow fiber membrane elements 2. The two hollow fiber membrane elements 2 are arranged in the extending direction D. The two hollow fiber membrane elements 2 are adjacent to each other in the extending direction D. Between the hollow fiber membrane elements 2 adjacent to each other in the extending direction D, the hollow portions 22a of the plurality of hollow fiber membranes 22 are connected to each other, and the hollow portions 21a of the liquid distribution pipes 21 are connected to each other. Of the two hollow fiber membrane elements 2, the hollow fiber membrane element 2 located on the first extending direction D1 side is referred to as the first hollow fiber membrane element 2α, and the hollow fiber membrane element 2 located on the second extending direction D2 side is referred to as the second hollow fiber membrane element 2β.

[0127] The element connecting pipe 12 is a member that connects the liquid circulation pipe 21 of the first hollow fiber membrane element 2α and the liquid circulation pipe 21 of the second hollow fiber membrane element 2β. The hollow portion 12a of the element connecting pipe 12 forms a space that communicates between the hollow portion 21a of the liquid circulation pipe 21 of the first hollow fiber membrane element 2α and the hollow portion 21a of the liquid circulation pipe 21 of the second hollow fiber membrane element 2β. The element connecting pipe 12 is connected to the end portion 21f of the liquid circulation pipe 21 of the first hollow fiber membrane element 2α and the end portion 21e of the liquid circulation pipe 21 of the second hollow fiber membrane element 2β so that the first hollow fiber membrane element 2α and the second hollow fiber membrane element 2β are spaced apart in the extending direction D. Therefore, a third communication space R13 is formed between the first hollow fiber membrane element 2α and the second hollow fiber membrane element 2β, which connects the hollow portions 22a of the multiple hollow fiber membranes 22 of the first hollow fiber membrane element 2α and the hollow portions 22a of the multiple hollow fiber membranes 22 of the second hollow fiber membrane element 2β.

[0128] The third communication space R13 is closed on its side in the first extending direction D1 by the second fixing part 25 of the first hollow fiber membrane element 2α and the second O-ring 5. The third communication space R13 is closed on its side in the second extending direction D2 by the first fixing part 24 of the second hollow fiber membrane element 2β and the first O-ring 4.

[0129] The first extending portion 61 of the first end member 6 is inserted into the end portion 21e of the liquid distribution pipe 21 of the first hollow fiber membrane element 2α and extends in the first extending direction D1 from the end portion 21e of the liquid distribution pipe 21 of the first hollow fiber membrane element 2α. Therefore, at least a portion of the first end member 6 is a member that is located on the first extending direction D1 side of the first hollow fiber membrane element 2α. The first extending portion 61 of the first end member 6 closes the end portion of the hollow portion 21a of the liquid distribution pipe 21 of the first hollow fiber membrane element 2α on the first extending direction D1 side.

[0130] The second extending portion 81 of the second end member 8 is inserted into the end portion 21f of the liquid circulation pipe 21 of the second hollow fiber membrane element 2β and extends in the second extending direction D2 from the end portion 21f of the liquid circulation pipe 21 of the second hollow fiber membrane element 2β. Therefore, at least a portion of the second end member 8 is a member located on the second extending direction D2 side of the second hollow fiber membrane element 2β. A liquid supply port A is formed in the hollow portion of the second extending portion 81, and is in communication with the hollow portion 21a of the liquid circulation pipe 21 of the second hollow fiber membrane element 2β.

[0131] The housing 3B has a first liquid discharge section 32Ba that forms the first liquid discharge port B1, a second liquid discharge section 32Bb that forms the second liquid discharge port B2, a first suction section 33Ba that forms the first gas port C1, a second suction section 33Bb that forms the second gas port C2, and a third suction section 33Bc that forms the third gas port C3. The first liquid discharge port B1 and the second liquid discharge port B2 are ports for discharging the liquid L that has come out of the hollow section 21a of the liquid distribution pipe 21. The first gas port C1, the second gas port C2, and the third gas port C3 are ports that communicate with the hollow sections 22a of the plurality of hollow fiber membranes 22.

[0132] The first liquid discharge port B1 is a port that penetrates the housing 3B. The first liquid discharge port B1 is formed in the cylindrical portion 31B at a position between the first fixing portion 24 and the second fixing portion 25 of the first hollow fiber membrane element 2α in the extending direction D, and is connected to the outer region R2 adjacent to the cylindrical portion 31B. The second liquid discharge port B2 is a port that penetrates the housing 3B. The second liquid discharge port B2 is formed in the cylindrical portion 31B at a position between the first fixing portion 24 and the second fixing portion 25 of the second hollow fiber membrane element 2β in the extending direction D, and is connected to the outer region R2 adjacent to the cylindrical portion 31B.

[0133] The first gas port C1 is a port that penetrates the housing 3B. The first gas port C1 is formed in the cylindrical portion 31B at a position adjacent to the first communication space R11 and is in communication with the first communication space R11. The second gas port C2 is a port that penetrates the housing 3B. The second gas port C2 is formed in the cylindrical portion 31B at a position adjacent to the second communication space R12 and is in communication with the second communication space R12. The third gas port C3 is a port that penetrates the housing 3B. The third gas port C3 is formed in the cylindrical portion 31B at a position adjacent to the third communication space R13 and is in communication with the third communication space R13.

[0134] [First degassing method according to the third embodiment: vacuum mode] Next, a description will be given of a first degassing method according to the third embodiment. The first degassing method according to the third embodiment is a method for degassing the liquid L in a vacuum mode using the hollow fiber membrane module 1B.

[0135] In this first degassing method, the first gas port C1, second gas port C2, and third gas port C3 of the hollow fiber membrane module 1B are suctioned, and the liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1B.

[0136] When the first gas port C1, the second gas port C2, and the third gas port C3 are suctioned, the internal region R1 connected to the first gas port C1, the second gas port C2, and the third gas port C3 is suctioned, and the hollow portions 22a of the plurality of hollow fiber membranes 22 of each of the first hollow fiber membrane element 2α and the second hollow fiber membrane element 2β are reduced in pressure. When liquid L is supplied to the liquid supply port A, the liquid L is supplied from the end portion 21f of the liquid distribution pipe 21 of the second hollow fiber membrane element 2β to the hollow portion 21a of the liquid distribution pipe 21 of the second hollow fiber membrane element 2β, and further through the hollow portion 12a of the element connecting pipe 12 to be supplied to the hollow portion 21a of the liquid distribution pipe 21 of the first hollow fiber membrane element 2α.

[0137] The liquid L supplied to the hollow portion 21a of the liquid circulation pipe 21 of the second hollow fiber membrane element 2β is discharged from the plurality of openings 21d of the liquid circulation pipe 21 of the second hollow fiber membrane element 2β into the space outside the liquid circulation pipe 21, where it is degassed by contact with the plurality of hollow fiber membranes 22 of the second hollow fiber membrane element 2β, and then discharged from the second liquid discharge port B2. The liquid L supplied to the hollow portion 21a of the liquid circulation pipe 21 of the first hollow fiber membrane element 2α is discharged from the plurality of openings 21d of the liquid circulation pipe 21 of the first hollow fiber membrane element 2α into the space outside the liquid circulation pipe 21, where it is degassed by contact with the plurality of hollow fiber membranes 22 of the first hollow fiber membrane element 2α, and then discharged from the first liquid discharge port B1.

[0138] Degassing of the liquid L in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α is achieved by allowing gases such as dissolved gas in the liquid L and bubbles contained in the liquid L to permeate the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α, pass through the hollow portions 22a of the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α, the first communicating space R11, the second communicating space R12, and the third communicating space R13, and be discharged from the first gas port C1, the second gas port C2, and the third gas port C3.

[0139] [Second degassing method according to the third embodiment: sweep mode] Next, a description will be given of a second degassing method according to the third embodiment. The second degassing method according to the third embodiment is a method for degassing the liquid L in a sweep mode using the hollow fiber membrane module 1B.

[0140] In this second degassing method, a sweep gas is supplied to the third gas port C3 of the hollow fiber membrane module 1B, and a liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1B. Note that the sweep gas may be supplied to at least one of the first gas port C1 and the second gas port C2 instead of the third gas port C3.

[0141] When a sweep gas is supplied to the third gas port C3, the sweep gas passes through the third communication space R13, the hollow portions 22a of the plurality of hollow fiber membranes 22 in each of the first hollow fiber membrane element 2α and the second hollow fiber membrane element 2β, the first communication space R11, and the second communication space R12, and flows from the third gas port C3 to the first gas port C1 and the second gas port C2, and is discharged from the first gas port C1 and the second gas port C2. When liquid L is supplied to the liquid supply port A, the liquid L flows through the same path as in the first degassing method. The liquid L is degassed by contact with the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α.

[0142] Degassing of the liquid L in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α is achieved by allowing gases such as dissolved gas in the liquid L and bubbles contained in the liquid L to permeate the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α, pass through the hollow portions 22a, the first communicating space R11, the second communicating space R12, and the third communicating space R13 of the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α, and be discharged from the first gas port C1 and the second gas port C2 together with the sweep gas.

[0143] [Third degassing method according to the third embodiment: combo mode] Next, a description will be given of a third degassing method according to the third embodiment. The third degassing method according to the third embodiment is a method for degassing the liquid L in a combo mode using the hollow fiber membrane module 1B.

[0144] In this third degassing method, a sweep gas is supplied to the third gas port C3 of the hollow fiber membrane module 1B, the first gas port C1 and the second gas port C2 of the hollow fiber membrane module 1B are suctioned, and the liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1B. Note that a sweep gas may be supplied to at least one of the first gas port C1 and the second gas port C2 instead of the third gas port C3, and the remaining gas port may be suctioned.

[0145] When a sweep gas is supplied to the third gas port C3, the sweep gas flows from the third gas port C3 through the third communication space R13, the hollow portions 22a of the hollow fiber membranes 22 in each of the first hollow fiber membrane element 2α and the second hollow fiber membrane element 2β, the first communication space R11, and the second communication space R12 to the first gas port C1 and the second gas port C2. When the first gas port C1 and the second gas port C2 are suctioned, the sweep gas supplied from the third gas port C3 is sucked toward the first gas port C1 and the second gas port C2 and discharged from the first gas port C1 and the second gas port C2. When liquid L is supplied to the liquid supply port A, the liquid L flows along the same path as in the first degassing method. The liquid L is degassed by contact with the hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α.

[0146] Degassing of the liquid L in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α is achieved by allowing gases such as dissolved gas in the liquid L and bubbles contained in the liquid L to permeate the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α, pass through the hollow portions 22a, the first communicating space R11, the second communicating space R12, and the third communicating space R13 of the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α, and be discharged from the first gas port C1 and the second gas port C2 together with the sweep gas.

[0147] [Gas Addition Method According to Third Embodiment] Next, a description will be given of a gas addition method according to a third embodiment. The gas addition method according to the third embodiment is a method for adding a gas to a liquid L using a hollow fiber membrane module 1B.

[0148] In this gas addition method, gas is supplied to the first gas port C1, second gas port C2, and third gas port C3 of the hollow fiber membrane module 1B, and liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1B.

[0149] When gas is supplied to the first gas port C1, the second gas port C2, and the third gas port C3, the gas is supplied to the hollow portions 22a of the plurality of hollow fiber membranes 22 of the first hollow fiber membrane element 2α and the second hollow fiber membrane element 2β, which are connected to the first gas port C1, the second gas port C2, and the third gas port C3, respectively, and the hollow portions 22a of the plurality of hollow fiber membranes 22 of the first hollow fiber membrane element 2α and the second hollow fiber membrane element 2β are pressurized. That is, gas is supplied to the first gas port C1, the second gas port C2, and the third gas port C3 so that the gas supplied to the first gas port C1, the second gas port C2, and the third gas port C3 pressurizes the hollow portions 22a of the plurality of hollow fiber membranes 22 of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α. Furthermore, when liquid L is supplied to the liquid supply port A, the liquid L flows through the same path as in the first degassing method. Then, gas is added to the liquid L in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α.

[0150] The addition of gas to the liquid L in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α is achieved by the gas supplied to the first gas port C1, the second gas port C2, and the third gas port C3 permeating through the multiple hollow fiber membranes 22 in each of the second hollow fiber membrane element 2β and the first hollow fiber membrane element 2α and coming into contact with the liquid L.

[0151] As described above, in the hollow fiber membrane module 1B according to the third embodiment, two hollow fiber membrane elements 2 are housed in the housing 3B, and the liquid circulation pipes 21 of adjacent hollow fiber membrane elements 2 in the extension direction D are connected by the element connection pipe 12, so that a large volume of liquid can be degassed.

[0152] [Hollow fiber membrane module according to the fourth embodiment] Next, a hollow fiber membrane module according to a fourth embodiment will be described. The hollow fiber membrane module according to the fourth embodiment is basically the same as the hollow fiber membrane module 1A according to the second embodiment, but differs from the hollow fiber membrane module 1A according to the second embodiment in that a plurality of hollow fiber membrane elements are housed in a housing. Therefore, in the following description, only the differences from the hollow fiber membrane module 1A according to the second embodiment will be described, and descriptions similar to those of the hollow fiber membrane module 1A according to the second embodiment will be omitted.

[0153] Fig. 12 is a schematic cross-sectional view of a hollow fiber membrane module according to the fourth embodiment. As shown in Fig. 12, the hollow fiber membrane module 1C according to the fourth embodiment is the hollow fiber membrane module 1A according to the second embodiment, in which two hollow fiber membrane elements are accommodated in the housing. The hollow fiber membrane module 1C includes two hollow fiber membrane elements 2A, a housing 3C, two first O-rings 4, two second O-rings 5, a first end member 6A, a third O-ring 7A, a second end member 8, a fourth O-ring 9, a first snap ring 10, a second snap ring 11, and an element connecting pipe 12C.

[0154] The housing 3C is formed in a cylindrical shape and has a cylindrical portion 31C that houses two hollow fiber membrane elements 2A. The two hollow fiber membrane elements 2A are arranged in the extending direction D. The two hollow fiber membrane elements 2A are adjacent to each other in the extending direction D. Between the hollow fiber membrane elements 2A adjacent to each other in the extending direction D, the hollow portions 22a of the plurality of hollow fiber membranes 22 are connected to each other, and the hollow portions 21a of the liquid distribution pipes 21 are connected to each other. Of the two hollow fiber membrane elements 2A, the hollow fiber membrane element 2A located on the first extending direction D1 side is referred to as the first hollow fiber membrane element 2Aα, and the hollow fiber membrane element 2A located on the second extending direction D2 side is referred to as the second hollow fiber membrane element 2Aβ.

[0155] The element connecting pipe 12C is a member that connects the liquid circulation pipe 21 of the first hollow fiber membrane element 2Aα and the liquid circulation pipe 21 of the second hollow fiber membrane element 2Aβ. The hollow portion 12Ca of the element connecting pipe 12C forms a space that communicates between the hollow portion 21a of the liquid circulation pipe 21 of the first hollow fiber membrane element 2Aα and the hollow portion 21a of the liquid circulation pipe 21 of the second hollow fiber membrane element 2Aβ. The element connecting pipe 12C is connected to the end portion 21f of the liquid circulation pipe 21 of the first hollow fiber membrane element 2Aα and the end portion 21e of the liquid circulation pipe 21 of the second hollow fiber membrane element 2Aβ so that the first hollow fiber membrane element 2Aα and the second hollow fiber membrane element 2Aβ are spaced apart in the extending direction D. Therefore, a fourth communication space R14 is formed between the first hollow fiber membrane element 2Aα and the second hollow fiber membrane element 2Aβ, which connects the hollow portions 22a of the multiple hollow fiber membranes 22 of the first hollow fiber membrane element 2Aα with the hollow portions 22a of the multiple hollow fiber membranes 22 of the second hollow fiber membrane element 2Aβ.

[0156] The fourth communicating space R14 is closed on its side in the first extending direction D1 by the second fixing part 25 of the first hollow fiber membrane element 2Aα and the second O-ring 5. The fourth communicating space R14 is closed on its side in the second extending direction D2 by the first fixing part 24 of the second hollow fiber membrane element 2Aβ and the first O-ring 4.

[0157] The first extending portion 61A of the first end member 6A is inserted into the end portion 21e of the liquid circulation pipe 21 of the first hollow fiber membrane element 2Aα and extends in the first extending direction D1 from the end portion 21e of the liquid circulation pipe 21 of the first hollow fiber membrane element 2Aα. Therefore, at least a portion of the first end member 6A is a member located on the first extending direction D1 side of the first hollow fiber membrane element 2Aα. A liquid discharge port B that communicates with the hollow portion 21a of the liquid circulation pipe 21 of the first hollow fiber membrane element 2Aα is formed in the hollow portion of the first extending portion 61A.

[0158] The second extending portion 81 of the second end member 8 is inserted into the end portion 21f of the liquid circulation pipe 21 of the second hollow fiber membrane element 2Aβ and extends in the second extending direction D2 from the end portion 21f of the liquid circulation pipe 21 of the second hollow fiber membrane element 2Aβ. Therefore, at least a portion of the second end member 8 is a member located on the second extending direction D2 side of the second hollow fiber membrane element 2Aβ. A liquid supply port A is formed in the hollow portion of the second extending portion 81, and is connected to the hollow portion 21a of the liquid circulation pipe 21 of the second hollow fiber membrane element 2Aβ.

[0159] The housing 3C has a first suction portion 33Ca that forms the first gas port C1, a second suction portion 33Cb that forms the second gas port C2, and a third suction portion 33Cc that forms the third gas port C3. The first gas port C1, the second gas port C2, and the third gas port C3 are ports that communicate with the hollow portions 22a of the multiple hollow fiber membranes 22 of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα.

[0160] The first gas port C1 is a port that penetrates the housing 3C. The first gas port C1 is formed in the cylindrical portion 31C at a position adjacent to the first communication space R11 and is in communication with the first communication space R11. The second gas port C2 is a port that penetrates the housing 3C. The second gas port C2 is formed in the cylindrical portion 31C at a position adjacent to the second communication space R12 and is in communication with the second communication space R12. The third gas port C3 is a port that penetrates the housing 3C. The third gas port C3 is formed in the cylindrical portion 31C at a position adjacent to the fourth communication space R14 and is in communication with the fourth communication space R14.

[0161] [First degassing method according to the fourth embodiment: vacuum mode] Next, a first degassing method according to the fourth embodiment will be described. The first degassing method according to the fourth embodiment is a method for degassing the liquid L in a vacuum mode using a hollow fiber membrane module 1C.

[0162] In this first degassing method, the first gas port C1, the second gas port C2, and the third gas port C3 of the hollow fiber membrane module 1C are suctioned, and the liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1C.

[0163] When the first gas port C1, the second gas port C2, and the third gas port C3 are suctioned, the internal region R1 connected to the first gas port C1, the second gas port C2, and the third gas port C3 is suctioned, and the hollow portions 22a of the plurality of hollow fiber membranes 22 of the first hollow fiber membrane element 2Aα and the second hollow fiber membrane element 2Aβ are brought into a decompressed state. Furthermore, when liquid L is supplied to the liquid supply port A, the liquid L is supplied from the second-end liquid distribution pipe opening 21c of the second hollow fiber membrane element 2Aβ to the hollow portion 21a of the liquid distribution pipe 21 of the second hollow fiber membrane element 2Aβ. Thereafter, in the second hollow fiber membrane element 2Aβ, the liquid L exits the liquid circulation pipe 21 from the opening 21d of the second pipe section 212, passes through the plurality of hollow fiber membranes 22 while being degassed by contacting them, passes through the gap between the inter-membrane baffle 27 and the cylindrical section 31C, passes through the plurality of hollow fiber membranes 22 while being degassed by contacting them again, returns to the hollow section 21a of the liquid circulation pipe 21 from the opening 21d of the first pipe section 211, and is supplied to the hollow section 21a of the liquid circulation pipe 21 of the first hollow fiber membrane element 2α through the hollow section 12Ca of the element connecting pipe 12C. The liquid L supplied to the hollow portion 21a of the liquid circulation pipe 21 of the first hollow fiber membrane element 2α exits the liquid circulation pipe 21 from the opening 21d of the second pipe portion 212 in the first hollow fiber membrane element 2Aα, passes through the plurality of hollow fiber membranes 22 while being degassed by contacting them, passes through the gap between the inter-membrane baffle 27 and the cylindrical portion 31C, passes through the plurality of hollow fiber membranes 22 while being degassed by contacting them again, returns to the hollow portion 21a of the liquid circulation pipe 21 from the opening 21d of the first pipe portion 211, and is discharged from the liquid discharge port B.

[0164] Degassing of the liquid L in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα is achieved by allowing gases such as dissolved gas in the liquid L and bubbles contained in the liquid L to permeate the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα, pass through the hollow portions 22a of the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα, the first communicating space R11, the second communicating space R12, and the fourth communicating space R14, and be discharged from the first gas port C1, the second gas port C2, and the third gas port C3.

[0165] [Second degassing method according to the fourth embodiment: sweep mode] Next, a description will be given of a second degassing method according to the fourth embodiment. The second degassing method according to the fourth embodiment is a method for degassing the liquid L in a sweep mode using a hollow fiber membrane module 1C.

[0166] In this second degassing method, a sweep gas is supplied to the third gas port C3 of the hollow fiber membrane module 1C, and a liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1C. Note that the sweep gas may be supplied to at least one of the first gas port C1 and the second gas port C2 instead of the third gas port C3.

[0167] When a sweep gas is supplied to the third gas port C3, the sweep gas passes through the fourth communication space R14, the hollow portions 22a of the plurality of hollow fiber membranes 22 in each of the first hollow fiber membrane element 2Aα and the second hollow fiber membrane element 2Aβ, the first communication space R11, and the second communication space R12, and flows from the third gas port C3 to the first gas port C1 and the second gas port C2, and is discharged from the first gas port C1 and the second gas port C2. When liquid L is supplied to the liquid supply port A, the liquid L flows through a path similar to that in the first degassing method. The liquid L is degassed by contact with the hollow portions 22a of the plurality of hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα.

[0168] Degassing of the liquid L in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα is achieved by allowing gases such as dissolved gas in the liquid L and bubbles contained in the liquid L to permeate the multiple hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα, pass through the hollow portions 22a of the multiple hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα, the first communicating space R11, the second communicating space R12, and the fourth communicating space R14, and be discharged from the first gas port C1 and the second gas port C2 together with the sweep gas.

[0169] [Third degassing method according to the fourth embodiment: combo mode] Next, a description will be given of a third degassing method according to the fourth embodiment. The third degassing method according to the fourth embodiment is a method for degassing the liquid L in a combo mode using a hollow fiber membrane module 1C.

[0170] In this third degassing method, a sweep gas is supplied to the third gas port C3 of the hollow fiber membrane module 1C, the first gas port C1 and the second gas port C2 of the hollow fiber membrane module 1C are suctioned, and the liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1C. Note that a sweep gas may be supplied to at least one of the first gas port C1 and the second gas port C2 instead of the third gas port C3, and the remaining gas port may be suctioned.

[0171] When a sweep gas is supplied to the third gas port C3, the sweep gas flows from the third gas port C3 through the fourth communication space R14, the hollow portions 22a of the hollow fiber membranes 22 in each of the first hollow fiber membrane element 2Aα and the second hollow fiber membrane element 2Aβ, the first communication space R11, and the second communication space R12 to the first gas port C1 and the second gas port C2. When the first gas port C1 and the second gas port C2 are suctioned, the sweep gas supplied from the third gas port C3 is sucked toward the first gas port C1 and the second gas port C2 and discharged from the first gas port C1 and the second gas port C2. When liquid L is supplied to the liquid supply port A, the liquid L flows along the same path as in the first degassing method and is degassed by coming into contact with the hollow portions 22a of the hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα.

[0172] Degassing of the liquid L in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα is achieved by allowing gases such as dissolved gas in the liquid L and bubbles contained in the liquid L to permeate the multiple hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα, pass through the hollow portions 22a of the multiple hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα, the first communicating space R11, the second communicating space R12, and the fourth communicating space R14, and be discharged from the first gas port C1 and the second gas port C2 together with the sweep gas.

[0173] [Gas Addition Method According to Fourth Embodiment] Next, a gas addition method according to a fourth embodiment will be described. The gas addition method according to the fourth embodiment is a method for adding a gas to a liquid L using a hollow fiber membrane module 1C.

[0174] In this gas addition method, gas is supplied to the first gas port C1, second gas port C2, and third gas port C3 of the hollow fiber membrane module 1C, and liquid L is supplied to the liquid supply port A of the hollow fiber membrane module 1C.

[0175] When gas is supplied to the first gas port C1, the second gas port C2, and the third gas port C3, the gas is supplied to the hollow portions 22a of the plurality of hollow fiber membranes 22 of the first hollow fiber membrane element 2Aα and the second hollow fiber membrane element 2Aβ, which are connected to the first gas port C1, the second gas port C2, and the third gas port C3, respectively, and the hollow portions 22a of the plurality of hollow fiber membranes 22 of the first hollow fiber membrane element 2Aα and the second hollow fiber membrane element 2Aβ are pressurized. That is, gas is supplied to the first gas port C1, the second gas port C2, and the third gas port C3 so that the gas supplied to the first gas port C1, the second gas port C2, and the third gas port C3 pressurizes the hollow portions 22a of the plurality of hollow fiber membranes 22 of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα. Furthermore, when liquid L is supplied to the liquid supply port A, the liquid L flows through the same path as in the first degassing method. Then, gas is added to the liquid L in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα.

[0176] The addition of gas to the liquid L in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα is achieved by the gas supplied to the first gas port C1, the second gas port C2, and the third gas port C3 permeating through the multiple hollow fiber membranes 22 in each of the second hollow fiber membrane element 2Aβ and the first hollow fiber membrane element 2Aα and coming into contact with the liquid L.

[0177] As described above, in the hollow fiber membrane module 1C according to the fourth embodiment, two hollow fiber membrane elements 2A are housed in the housing 3C, and the liquid flow pipes 21 of adjacent hollow fiber membrane elements 2A in the extension direction D are connected by the element connection pipe 12C, thereby improving degassing performance.

[0178] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments.

[0179] For example, in the above embodiment, the cylindrical portion constituting the housing is described as not having lids attached to both ends, but the cylindrical portion constituting the housing may have lids attached to both ends. In this case, the liquid supply port or liquid discharge port formed in the first end member or the second end member may be formed in the lids attached to both ends of the cylindrical portion.

[0180] Furthermore, the hollow fiber membrane elements according to the second and fourth embodiments have been described as being provided with inter-membrane baffles, but they may not be provided with inter-membrane baffles.

[0181] In addition, although the third and fourth embodiments have been described as having two hollow fiber membrane elements housed in a housing, three or more hollow fiber membrane elements may be housed in a housing. In this case, by connecting the liquid flow pipes of adjacent hollow fiber membrane elements in the extension direction with an element connection pipe, liquid can be circulated in the same manner as in the third and fourth embodiments.

[0182] In the above embodiments, the housing is described as having multiple gas ports, but the number of gas ports is not particularly limited as long as it can degas or add gas to the liquid. For example, in the third and fourth embodiments, the housing is described as having three gas ports: the first gas port C1, the second gas port C2, and the third gas port C3. However, the third gas port C3 may be omitted. In this case, in the second and third degassing methods, the liquid can be degassed by supplying a sweep gas to the first gas port C1 or the second gas port C2.

[0183] Furthermore, in the above embodiment, the first end member and the second end member are described as being configured by each extension portion and each flange portion being integrally formed, but the extension portion and each flange portion may also be formed by separate members that are combined with each other.

[0184] In the above embodiment, the first end member and the second end member are attached to the cylindrical portion by engaging the first flange portion of the first end member and the second flange portion of the second end member with a snap ring, but the attachment structure of the first end member and the second end member to the cylindrical portion is not particularly limited. For example, the first end member and the second end member may be screwed into the cylindrical portion, the cylindrical portion may be screwed into the first end member and the second end member, or the cylindrical portion may be fixed to the first end member and the second end member with a V-band.

[0185] Furthermore, in the above embodiment, the first end member and the second end member are described as being arranged inside the cylindrical portion, but the structure may also be such that some or all of the first end member and the second end member are arranged outside the cylindrical portion, and the first end member and the second end member are attached to the cylindrical portion so as to cover the cylindrical portion. [Explanation of symbols]

[0186] 1...hollow fiber membrane module, 1A...hollow fiber membrane module, 1B...hollow fiber membrane module, 1C...hollow fiber membrane module, 2...hollow fiber membrane element, 2A...hollow fiber membrane element, 2α...first hollow fiber membrane element, 2β...second hollow fiber membrane element, 2Aα...first hollow fiber membrane element, 2Aβ...second hollow fiber membrane element, 2a...first element end, 2b...second element end, 2c...element middle part, 3...housing, 3A...housing, 3B...housing, 3C...housing, 4...first O-ring, 5...second O-ring, 6...first end member, 6A...first end member, 7... Third O-ring, 7A...third O-ring, 8...second end member, 9...fourth O-ring, 10...first snap ring, 11...second snap ring, 12...element connecting pipe, 12a...hollow portion, 12C...element connecting pipe, 12Ca...hollow portion, 21...liquid distribution pipe, 21a...hollow portion, 21b...first end liquid distribution pipe opening, 21c...second end liquid distribution pipe opening, 21d...opening, 21e...end, 21f...end, 22...hollow fiber membrane, 22a...hollow portion, 22b...first end hollow fiber membrane opening, 22c...second end hollow fiber membrane opening, 24...first fixing portion, 24a...outer circumferential surface, 24b...first O Ring groove, 24c...fixing part, 24d...groove forming part, 24e...recess, 25...second fixing part, 25a...outer circumferential surface, 25b...second O-ring groove, 25c...fixing part, 25d...groove forming part, 25e...recess, 26...baffle, 27...intermembrane baffle, 31...cylindrical part, 31A...cylindrical part, 31B...cylindrical part, 3 1C...Cylindrical part, 32...Liquid discharge part, 32Ba...First liquid discharge part, 32Bb...Second liquid discharge part, 33a...First suction part, 33b...Second suction part, 33Aa...First suction part, 33Ab...Second suction part, 33Ba...First suction part, 33Bb...Second suction part, 33Bc...Third suction part, 33Ca...First Suction portion, 33Cb...second suction portion, 33Cc...third suction portion, 35...first snap ring groove, 36...second snap ring groove, 61...first extension portion, 61A...first extension portion, 62...first flange portion, 62a...outer peripheral surface, 62b...third O-ring groove, 62A...first flange portion, 62Aa...outer peripheral surface, 62Ab...third O-ring groove, 81...second extension portion, 82...second flange portion, 82a...outer peripheral surface, 82b...fourth O-ring groove, 211...first pipe portion, 212...second pipe portion, A...liquid supply port, B...liquid discharge port, B1...first liquid discharge port, B2...second liquid discharge port,C1…First Gaspot, C2…Second Gaspot, C3…Third Gaspot, D…Extension Direction, D1…First Extension Direction, D2…Second Extension Direction, L…Liquid, R1…Inner Domain, R2…Outer Domain, R11…First Connected Space, R12…Second Connected Space, R13…Third Connected Space, R14…Fourth Connected Space.

Claims

1. a liquid flow pipe having a plurality of openings formed therein; a plurality of hollow fiber membranes arranged around the liquid distribution pipe so as to extend along the liquid distribution pipe and cover the plurality of openings; a first fixing portion located at an end of the liquid distribution pipe in a first extension direction, which is one of the extension directions of the liquid distribution pipe, and fixing 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 to leave open a hollow portion of the liquid distribution pipe and hollow portions of the plurality of hollow fiber membranes; a second fixing portion located at an end in a second extending direction, which is the other direction in the extending direction, and fixing 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 to leave the hollow portion of the liquid distribution pipe and the hollow portions of the plurality of hollow fiber membranes open, An O-ring groove for fitting an O-ring therein is formed on the outer circumferential surface of each of the first fixing portion and the second fixing portion. Hollow fiber membrane element.

2. Each of the first fixing portion and the second fixing portion is a fixing portion that fixes the plurality of hollow fiber membranes to the liquid distribution pipe; a groove forming portion having the O-ring groove formed on an outer peripheral surface thereof, The hollow fiber membrane element according to claim 1.

3. The hollow portion of the liquid circulation pipe is in communication from a tip end in the first extension direction to a tip end in the second extension direction. The hollow fiber membrane element according to claim 1.

4. a baffle that closes the hollow portion of the liquid circulation pipe at an intermediate portion of the element between the first fixed portion and the second fixed portion in the extension direction; The hollow fiber membrane element according to claim 1.

5. further comprising an inter-membrane baffle that closes spaces between the plurality of hollow fiber membranes in the middle portion of the element; The hollow fiber membrane element according to claim 4.

6. The hollow fiber membrane element according to any one of claims 1 to 5, a housing that accommodates the hollow fiber membrane element; a liquid supply port for supplying liquid to the hollow portion of the liquid circulation pipe; a liquid discharge port for discharging the liquid discharged from the liquid distribution pipe; a gas port communicating with the hollow portions of the plurality of hollow fiber membranes; a first O-ring fitted into the O-ring groove formed in the first fixed portion and pressed against the first fixed portion and the housing; a second O-ring fitted into the O-ring groove formed in the second fixing portion and pressed against the second fixing portion and the housing, Hollow fiber membrane module.

7. the housing has a cylindrical portion formed in a cylindrical shape and accommodating the hollow fiber membrane element; the first O-ring is pressed against the first fixing portion and the cylindrical portion, The second O-ring is pressed against the second fixing portion and the cylindrical portion. The hollow fiber membrane module according to claim 6.

8. a first end member having a first extension portion housed in the cylindrical portion and extending in the extension direction, and a first flange portion extending from the first extension portion toward the cylindrical portion and having an O-ring groove formed on its outer peripheral surface for fitting an O-ring therein, at least a portion of which is positioned closer to the hollow fiber membrane element in the first extension direction; a second end member having a second extension portion accommodated in the cylindrical portion and extending in the extension direction, and a second flange portion extending from the second extension portion toward the cylindrical portion and having an O-ring groove formed on its outer peripheral surface for fitting an O-ring therein, at least a portion of which is positioned closer to the second extension direction than the hollow fiber membrane element; a third O-ring fitted into the O-ring groove formed in the first end member and pressed against the first end member and the cylindrical portion; a fourth O-ring fitted into the O-ring groove formed in the second end member and pressed against the second end member and the cylindrical portion, The hollow fiber membrane module according to claim 7.

9. a first snap ring that hooks the first flange portion from the first extending direction side; a second snap ring that hooks the second flange portion from the second extending direction side, A first snap ring groove into which the first snap ring is fitted and a second snap ring groove into which the second snap ring is fitted are formed on the inner peripheral surface of the cylindrical portion. The hollow fiber membrane module according to claim 8.

10. the hollow portion of the liquid circulation pipe is in communication from a tip end in the first extension direction to a tip end in the second extension direction, and is closed at an end portion in the first extension direction by the first end member, a communication space communicating with the hollow portions of the plurality of hollow fiber membranes is formed between at least one of the first flange portion and the second flange portion and the hollow fiber membrane element, the liquid supply port is formed in the second extension portion and communicates with an end portion of the hollow portion of the liquid circulation pipe in the second extension direction, the liquid discharge port is formed in the cylindrical portion at a position between the first fixed portion and the second fixed portion in the extension direction, the gas port is formed in the cylindrical portion at a position adjacent to the communication space, The hollow fiber membrane module according to claim 8.

11. the hollow portion of the liquid circulation pipe is closed by a baffle in an element intermediate portion between the first fixed portion and the second fixed portion in the extension direction, a communication space communicating with the hollow portions of the plurality of hollow fiber membranes is formed between at least one of the first flange portion and the second flange portion and the hollow fiber membrane element, the liquid supply port is formed in the second extension portion and communicates with an end portion of the hollow portion of the liquid circulation pipe in the second extension direction, the liquid discharge port is formed in the first extension portion and communicates with an end portion of the hollow portion of the liquid circulation pipe in the first extension direction, the gas port is formed in the cylindrical portion at a position adjacent to the communication space, The hollow fiber membrane module according to claim 8.

12. A method for degassing a liquid using the hollow fiber membrane module according to claim 6, 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; Degassing method.

13. A degassing method for degassing a liquid using the hollow fiber membrane module according to claim 6, 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; Degassing method.

14. A gas addition method for adding a gas to a liquid using the hollow fiber membrane module according to claim 6, comprising: a gas is supplied to the 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 the liquid supply port of the hollow fiber membrane module; Gas addition method.

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