Hollow fiber membrane element, external pressure-type hollow fiber membrane module, operation method thereof, purification facility, and purification method

Abstract

The present invention provides a hollow fiber membrane element and an external pressure-type hollow fiber membrane module where it possible to uniformly arrange an interval between hollow fiber membranes and it is possible to prevent peeling or breakage of a potting part under high pressure conditions regardless of cutting accuracy even in a case where an end part of the potting part is cut in order to open an end part of the hollow fiber membranes.　The hollow fiber membrane element includes: a plurality of the hollow fiber membranes, which are inserted into a cylindrical housing; a potting part where the hollow fiber membranes and the cylindrical housing are integrated by adhesion on at least one end side of the cylindrical housing; and a spacer for dividing a radial cross section of the cylindrical housing into a plurality of regions, said element being characterized in that an end part, of the spacer, on a side where an outer surface of the hollow fiber membranes in the axial direction of the cylindrical housing is exposed is encapsulated by the potting part.

Description

Hollow fiber membrane element, external pressure type hollow fiber membrane module, and operation method thereof, purification equipment, and purification method

[0001] The present invention relates to a hollow fiber membrane element, an external pressure type hollow fiber membrane module, an operating method thereof, a purification facility, and a purification method.

[0002] Hollow fiber membrane modules are used in a wide range of business fields, such as water treatment, food industry, and gas separation, for the purpose of separating some of the components from a supplied mixed fluid. A hollow fiber membrane module generally comprises a hollow fiber membrane element, which is composed of a cylindrical housing, a plurality of hollow fiber membranes inserted inside the cylindrical housing, and a potting section, one or both ends of which are integrated with the end of the cylindrical housing by an adhesive resin, and a cap arranged to hermetically seal the end of the hollow fiber membrane element.

[0003] A hollow fiber membrane module using the above-mentioned hollow fiber membrane elements is operated in either an internal pressure type or an external pressure type, taking into consideration the physical properties of the mixed fluid, the amount of turbidity, etc. In the case of an external pressure type hollow fiber membrane module, the mixed fluid supplied to the hollow fiber membrane element passes between the hollow fiber membranes. During this process, some of the components in the mixed fluid are separated from the outside to the inside of the hollow fiber membranes. Therefore, compared to an internal pressure type hollow fiber membrane module of the same volume, this type has many advantages, such as lower pressure loss, a larger membrane area that allows for an improved separation throughput, and the ability to separate highly turbid fluids that cannot be separated using an internal pressure type.

[0004] On the other hand, in external pressure hollow fiber membrane modules, if the spacing between hollow fiber membranes in a hollow fiber membrane element is uneven, fluids have difficulty flowing through narrower spacing areas, preferentially passing through wider spacing areas, resulting in insufficient separation performance of the hollow fiber membranes. In response to this issue, Patent Document 1 provides a hollow fiber membrane element and an external pressure hollow fiber membrane module in which spacers are interposed at the ends of a cylindrical housing to ensure as even spacing between the hollow fiber membranes as possible, thereby enabling fluids to pass evenly between the hollow fiber membranes. Furthermore, a method utilizing centrifugal force is used to integrate the ends of the cylindrical housing and the ends of the hollow fiber membranes with an adhesive resin. In this process, the cylindrical housing is integrated in a horizontal position with its axial direction perpendicular to the direction of gravity, which tends to cause the hollow fiber membranes before integration to pack tightly together in the direction of gravity, resulting in uneven spacing between the hollow fiber membranes. Against this issue, the aforementioned spacers prevent the hollow fiber membranes from packing together in the direction of gravity and are effective in ensuring even spacing between the hollow fiber membranes inside the cylindrical housing.

[0005] Furthermore, when hollow fiber membrane elements and external pressure-type hollow fiber membrane modules are used for water treatment applications such as seawater desalination or gas separation applications for separating impurities such as carbon dioxide from natural gas, they are sometimes operated at extremely high pressures to achieve sufficient separation performance. When high pressure is applied to the hollow fiber membrane elements and external pressure-type hollow fiber membrane modules, a very large pressure difference occurs between the interior of the cylindrical housing where the supplied mixed fluid resides and the exterior of the cylindrical housing where the separated permeate fluid resides, i.e., in the potting section. Because the potting section is bonded to the inner wall surface of the end of the cylindrical housing, if a pressure difference occurs that exceeds the adhesive strength or the strength of the resin constituting the potting section, the potting section may peel or break, potentially resulting in the mixed fluid being mixed with the permeate fluid. In contrast, the external pressure-type hollow fiber membrane module disclosed in Patent Document 2 contacts fluid-permeable porous members with the potting sections at both ends of the hollow fiber membrane element, and the ends of the cylindrical housing are hermetically sealed with caps while the porous members are pressed down with caps. With this structure, the external pressure type hollow fiber membrane module can withstand the large pressure difference generated in the potting portion with the porous member and the cap, thereby preventing peeling or damage to the potting portion.

[0006] JP 2006-198495 A International Publication No. 2017 / 204123

[0007] However, to prevent the potting section from peeling or breaking during high-pressure operation using the method of Patent Document 2, the cap, porous member, and potting section must be manufactured with high dimensional precision and must be in contact with each other at the appropriate positions. In particular, when forming the potting section, the end of the potting section must be cut to open the end of the hollow fiber membrane embedded therein. At this time, the potting section must be cut with high precision to match the dimensions of the cap and porous member. For example, if the end of the potting section is cut longer than the specified dimension, when the end of the cylindrical housing is sealed with the cap while pressing down on the porous member, the porous member may exert a force that pushes the potting section toward the inside of the cylindrical housing, resulting in the potting section peeling or breaking. Furthermore, if the end of the potting section is cut shorter than the specified dimension, the potting section, the porous member, and cap will not be in proper contact, and the porous member will not be able to absorb the pressure difference generated in the potting section, which could result in the potting section peeling or breaking outside the cylindrical housing.

[0008] The present invention has been made in view of the above, and provides a hollow fiber membrane element and an external pressure type hollow fiber membrane module that can prevent peeling or damage to the potting portion, regardless of the cutting accuracy, even when the end of the potting portion is cut to open the end of the hollow fiber membrane, and that can arrange the hollow fiber membranes at equal intervals.

[0009] In order to solve the above problems, the present invention has the following configuration.

[0010] (1) A hollow fiber membrane element comprising: a plurality of hollow fiber membranes inserted into a cylindrical casing; a potting portion at least on one end side of the cylindrical casing, where the hollow fiber membranes and the cylindrical casing are integrated by bonding; and a spacer dividing the radial cross section of the interior of the cylindrical casing into a plurality of regions, wherein the end of the spacer in the axial direction of the cylindrical casing, where the outer surface of the hollow fiber membranes is exposed, is enclosed in the potting portion. (2) The hollow fiber membrane element described in (1), characterized in that a holding portion for holding the spacer is provided at the end of the cylindrical casing. (3) The hollow fiber membrane element described in (1) or (2), characterized in that the spacer is fixed in the axial direction within the cylindrical casing. (4) The hollow fiber membrane element described in (1) or (3), characterized in that the spacer is fixed in the axial direction by fitting the spacer with the inner wall of the cylindrical casing. (5) The hollow fiber membrane element according to (2) or (3), characterized in that the spacer is fixed in the axial direction by fitting the holding part with the spacer. (6) The hollow fiber membrane element according to any of (1) to (5), characterized in that the spacer divides the radial cross section of the interior of the cylindrical casing into a plurality of regions including polygonal or sectorial shapes by the spacer. (7) The hollow fiber membrane element according to any of (1) to (6), characterized in that the axial height of the spacer is 5 mm or more. (8) The hollow fiber membrane element according to any of (1) to (7), characterized in that the spacer is composed of an outer frame and partition plates that divide the interior of the outer frame into a plurality of regions. (9) The hollow fiber membrane element according to any of (1) to (8), characterized in that the spacer is made of a material with a bending strength equal to or greater than that of the adhesive resin used to form the potting part. (10) The hollow fiber membrane element according to any one of (1) to (9), characterized in that the membrane filling rate of the hollow fiber membranes inserted into the cylindrical casing is 30% or more and 65% or less.(11) An external pressure type hollow fiber membrane module comprising the hollow fiber membrane element according to any one of (1) to (10) and a cap arranged to hermetically seal an end of the hollow fiber membrane element, characterized in that one of the sharp ends of the spacer contacts the cap directly or via a potting part within a region of the spacer projected in the axial direction of the cylindrical casing.

[0011] (12) The external pressure type hollow fiber membrane module according to (11), characterized in that the means for bringing one end of the spacer into contact with the cap directly or via a potting part within the area projected in the axial direction of the cylindrical casing is a protrusion provided on the inner wall of the cap. (13) The external pressure type hollow fiber membrane module according to (11) or (12), characterized in that the only point of contact between the spacer and the cap, directly or via the potting part, is the outer frame of the spacer. (14) A method for operating a hollow fiber membrane element or an external pressure type hollow fiber membrane module, comprising separating a mixed fluid under the requirement that the mixed fluid supply pressure is 1 MPa or more and 30 MPa or less, using the hollow fiber membrane element or external pressure type hollow fiber membrane module according to any of (1) to (13). (15) A method for operating a hollow fiber membrane element or an external pressure type hollow fiber membrane module according to (14), characterized in that the mixed fluid is a gas. (16) A method for operating the hollow fiber membrane element or external pressure type hollow fiber membrane module according to (14), characterized in that the viscosity of the mixed fluid is 2 mPa s or more. (17) A method for operating the hollow fiber membrane element or external pressure type hollow fiber membrane module according to (14) or (16), characterized in that the turbidity of the mixed fluid is 20 NTU or more and the TOC concentration is 1000 mg / L or more. (18) A purification facility comprising the hollow fiber membrane element or external pressure type hollow fiber membrane module according to any of (1) to (13). (19) A purification facility for biogas or natural gas, comprising the hollow fiber membrane element or external pressure type hollow fiber membrane module according to any of (1) to (13). (20) A purification method for separating and purifying one component from a mixed fluid using the purification facility according to (16) or (17).

[0012] According to the present invention, it is possible to provide a hollow fiber membrane element and an external pressure type hollow fiber membrane module that can prevent peeling or damage to the potting portion, regardless of the cutting accuracy, even when the end of the potting portion is cut to open the end of the hollow fiber membrane, and that can arrange the hollow fiber membranes at equal intervals.

[0013] Schematic cross-sectional view showing a hollow fiber membrane element 1 according to an embodiment Schematic cross-sectional view showing a hollow fiber membrane element 1 according to an embodiment Schematic cross-sectional view and top view showing a hollow fiber membrane element 1 according to an embodiment Top view of a hollow fiber membrane element 1 according to an embodiment Top view of a hollow fiber membrane element 1 according to an embodiment Schematic cross-sectional view showing an external pressure-type hollow fiber membrane module 10 according to an embodiment Schematic cross-sectional view showing an external pressure-type hollow fiber membrane module 10 according to an embodiment Schematic cross-sectional view showing an external pressure-type hollow fiber membrane module 10 according to an embodiment Schematic cross-sectional view showing an external pressure-type hollow fiber membrane module 10 according to an embodiment Schematic cross-sectional view showing an external pressure-type hollow fiber membrane module 10 according to an embodiment Schematic cross-sectional view showing an external pressure-type hollow fiber membrane module 10 according to an embodiment Top view of an external pressure-type hollow fiber membrane module 10 according to an embodiment Schematic cross-sectional view showing an external pressure-type hollow fiber membrane module 10 according to an embodiment

[0014] A hollow fiber membrane element 1 (hereinafter referred to as element 1) and an external pressure type hollow fiber membrane module 10 (hereinafter referred to as module 10) according to an embodiment of the present invention will be described in detail below with reference to the drawings. Here, the external pressure type refers to a method in which a mixed fluid supplied from the outside of a hollow fiber membrane 12 is filtered toward the inside (hollow portion side) of the hollow fiber membrane 12. In this embodiment, the side from which the permeated fluid is discharged is referred to as "upper," and the side to which the mixed fluid is supplied is referred to as "lower." However, "upper" and "lower" are merely terms of convenience based on the state shown in the drawings and do not limit the present invention in any way. In addition, in the present invention, the "axial direction" corresponds to the height direction of the element 1 and module 10 (the up-down direction in Figures 1 and 6). The "radial direction" corresponds to the diameter direction of the element 1 and module 10, which is perpendicular to the axial direction (the left-right direction in Figures 1 and 6).

[0015] First, an example of the configuration of an element 1 according to an embodiment of the present invention will be described using the schematic cross-sectional view shown in Fig. 1. The element 1 is composed of a cylindrical casing 11, several hundred to several tens of thousands of hollow fiber membranes 12 inserted into the cylindrical casing 11, a potting portion 13 in which the hollow fiber membranes 12 and the cylindrical casing 11 are integrated with an adhesive resin, and spacers 20 contained in the upper potting portion 13(a) and which divide a cross section (hereinafter referred to as a radial cross section) into multiple regions when the interior of the cylindrical casing 11 is cut radially.

[0016] The cylindrical housing 11 is a hollow housing and may have any cross-sectional shape as long as the hollow fiber membranes 12 can be inserted therein. However, a cylindrical shape is preferable because stress concentration is less likely to occur in a part of the cylindrical housing 11 even when high pressure is applied inside the element 1. At least one non-permeated fluid outlet 31 for discharging the non-permeated fluid is provided on the side surface of the cylindrical housing 11. The non-permeated fluid outlet 31 may be provided directly on the side surface of the cylindrical housing 11 as shown in FIG. 1 . Alternatively, the non-permeated fluid outlet 31 may be connected to an outlet nozzle 33 provided on the side surface of the cylindrical housing 11, as in the element 1 used in the module 10 shown in FIG. 6 (to be described later). Furthermore, if the through-hole 15 (to be described later) is not provided in the lower potting portion 13(b), at least one mixed fluid supply port (not shown) for introducing the mixed fluid is provided on the side surface of the cylindrical housing 11.

[0017] The material of the cylindrical housing 11 may be appropriately selected depending on the components contained in the mixed fluid to be supplied and the supply pressure of the mixed fluid. Examples of the material include fluororesins such as polysulfone-based resins, polytetrafluoroethylene, and perfluoroalkoxy fluororesins, resin materials such as polycarbonate, polypropylene, polymethylpentene, polyphenylene sulfide, and polyether ketone, reinforced resins obtained by mixing these resin materials with glass fiber, carbon fiber, talc, and the like, and metal materials such as stainless steel and aluminum. Stainless steel is particularly preferred because of its excellent corrosion resistance and high strength.

[0018] The potting part 13 is formed by bonding and curing the end of the cylindrical casing 11 and the end of the hollow fiber membrane 12 with an adhesive resin. In the potting part 13 shown in FIG. 1 , the lower potting part 13(b) is provided with a through-hole 15 for introducing the mixed fluid into the cylindrical casing 11. On the other hand, the upper potting part 13(a) functions as a sealant that separates the non-permeating fluid from the permeating fluid, and contains a spacer 20 (described later) therein. Furthermore, as described above, if the mixed fluid supply port (not shown) is provided on the side surface of the cylindrical casing 11, a through-hole is not necessary in the lower potting part 13(b), and therefore the lower potting part 13(b) may have the same structure as the upper potting part 13(a).

[0019] The potting portion 13 is formed by attaching a potting jig (not shown) for forming the potting portion 13 to the end of the cylindrical housing 11 into which the hollow fiber membranes 12 have been inserted, pouring adhesive resin into the potting jig and the end of the cylindrical housing 11, and removing the potting jig after the resin has hardened. At this time, the hollow portion of the hollow fiber membrane 12 is sealed with the adhesive resin, so that the permeated fluid separated by the hollow fiber membrane 12 cannot be discharged to the outside of the element 1. Therefore, the end of the hollow fiber membrane 12 is sealed in advance with an adhesive or the like, and then the upper potting portion 13(a) is formed by the method described above. The sealed end of the hollow fiber membrane 12 is then cut off as an excess portion together with the end of the upper potting portion 13(a), thereby opening the hollow portion of the hollow fiber membrane 12. On the other hand, in the lower potting part 13(b), since there is no need to discharge the permeating fluid from the end of the hollow fiber membrane 12 contained therein, the end of the lower potting part 13(b) may be cut off for formation, but the end of the hollow fiber membrane 12 remains sealed with the adhesive resin.

[0020] The adhesive resin material used to form the potting portion 13 may be appropriately selected depending on the components contained in the supplied mixed fluid and the material of the object to be bonded. Examples include epoxy resin, polyurethane resin, silicone resin, and acrylic resin. These resin materials may also be mixed with glass fiber, carbon fiber, talc, etc. to improve strength. Therefore, to prevent the upper potting portion 13(a) from peeling or breaking from the cylindrical housing 11, the spacer 20 is bonded and cured inside the upper potting portion 13(a) together with the hollow fiber membranes 12, as shown in FIG. 1 , and the lower end 24 of the spacer 20, on the axial side where the outer surface of the hollow fiber membranes 12 is exposed, must be enclosed within the upper potting portion 13(a). When the mixed fluid is supplied to the element 1, the upper potting portion 13(a) is normally slightly deformed into an upwardly convex, arched shape due to the upward pressure. However, when the lower end 24 of the spacer 20 is enclosed within the upper potting portion 13(a), the spacer 20 acts as a beam to suppress minute deformation of the upper potting portion 13(a). Therefore, the local stress generated at the adhesive surface between the cylindrical housing 11 and the upper potting portion 13(a) due to minute deformation is reduced, achieving higher strength against peeling or breakage from the cylindrical housing 11. This makes it possible to achieve a peeling or breakage suppression effect of the upper potting portion 13(a) from the cylindrical housing 11 equivalent to or better than that of Patent Document 2, even without the structure for preventing peeling of the potting portion 13 due to contact between the upper potting portion 13(a) and the porous member as shown in Patent Document 2. In this case, because contact between the upper potting portion 13(a) and the porous member is not required, unlike the element 1 having the structure shown in Patent Document 2, the end of the upper potting portion 13(a) does not need to be precisely cut to fit the dimensions of the other components. 1, the upper end 23 of the spacer 20 is exposed from the upper potting portion 13(a). On the other hand, the upper end 23 of the spacer 20 may be enclosed within the upper potting portion 13(a) in the same manner as the lower end 24 of the spacer 20, and there is no difference between the two in terms of the effect of suppressing peeling or breakage of the upper potting portion 13(a) from the cylindrical housing 11.When the upper end 23 of the spacer 20 is enclosed in the upper potting portion 13(a), the hollow fiber membrane 12 does not exist within the area where the spacer 20 is projected upward.

[0021] Furthermore, in the schematic cross-sectional view of the element 1 shown in FIG. 2 , a retaining portion 17 in the shape of an L-shaped groove is provided at the end of the cylindrical housing 11, as shown in the detailed view of part A (only the cylindrical housing 11 is shown). In the region at the end of the cylindrical housing 11 where the hollow fiber membranes 12 can be inserted, if the sum of the radial cross-sectional areas, with the outer diameter of the hollow fiber membranes 12 as the diameter, relative to the area of ​​the hollow fiber membrane 12 insertable region (hereinafter referred to as the membrane packing rate) is 30% or less, it is not necessary to provide the retaining portion 17 shown in FIG. 2 at the end of the cylindrical housing 11. This is because the number of hollow fiber membranes 12 inserted into the element 1 is relatively small, and the hollow fiber membranes 12 can be inserted into the cylindrical housing 11 with a low load. On the other hand, if the membrane packing rate is greater than 30%, it is preferable to provide the retaining portion 17 shown in FIG. 2 . This is particularly effective when the spacer 20, described below, has an outer frame 21. This is because placing the outer frame 21 of the spacer 20 on the holding portion 17 prevents the hollow fiber membranes 12 from crowding around the spacer 20, allowing the hollow fiber membranes 12 to be inserted into the cylindrical housing 11 with a low load. Alternatively, the axial height H3 of the holding portion 17 may be designed to be greater than the axial height H1 of the spacer 20, and the upper end 23 of the spacer 20 placed on the holding portion 17 may be enclosed within the upper potting portion 13(a). On the other hand, as in the element 1 shown in FIG. 2 , the axial height H3 of the holding portion 17 is preferably the same dimension as the axial height H1 of the spacer 20. This is because, by restraining the spacer 20 on the holding portion 17 when forming the upper potting portion 13(a), axial displacement of the spacer 20 during adhesive curing is prevented.

[0022] At this time, it is preferable that the spacer 20 is fixed in the axial direction within the cylindrical housing 11. This allows the spacer 20 to bear the axial force generated in the upper potting portion 13(a) at the portion where the spacer 20 is fixed to the cylindrical housing 11, thereby achieving an even greater effect in suppressing peeling from the cylindrical housing 11 or breakage.

[0023] Furthermore, when the lower end 24 of the spacer 20 described above is enclosed within the upper potting portion 13(a), the spacer 20 and the inner wall of the cylindrical casing 11 are preferably fixed in the axial direction by fitting together. Furthermore, if a retaining portion 17 is provided at the end of the cylindrical casing 11, the spacer 20 is preferably fixed in the axial direction by fitting into the retaining portion 17. This more firmly fixes the spacer 20 in the axial direction within the cylindrical casing 11. Therefore, the spacer 20 can more effectively function as a beam within the upper potting portion 13(a), and can achieve an even greater effect in preventing the upper potting portion 13(a) from peeling off or breaking from the cylindrical casing 11. An example of the shape of the retaining portion 17 and the spacer 20 in this case is shown in FIG. 3. In Fig. 3(a), a retaining portion 17 is provided on the inner wall of the cylindrical housing 11, and the retaining portion 17 is made up of an insertion groove 26 into which the spacer 20 is inserted in the axial direction and a fixing groove 27 formed in the circumferential direction into which the spacer 20 is then rotated and fixed in the axial direction, and the spacer 20 is placed in the fixing groove 27. In Fig. 3(b), the retaining portion 17, which has a spiral recess and projection formed on the inner wall of the cylindrical housing 11, and the spacer 20, which has a spiral recess and projection that fits into the retaining portion 17, are fitted together in the axial direction by screw fastening, etc. Note that the means for fixing the spacer 20 in the axial direction shown in Fig. 3 is one example and does not limit the present invention in any way.

[0024] FIG. 4 is a top view of the element 1 in the embodiment shown in FIG. 1 . The spacer 20 is formed by combining plate-like partition plates 22 that divide the radial cross section inside the cylindrical housing 11 into multiple regions. In the upper potting section 13(a) containing the spacer 20, the hollow fiber membranes 12 are divided into multiple bundles and arranged in the region where the spacer 20 is not present. This allows the hollow fiber membranes 12 to be inserted evenly inside the cylindrical housing 11, allowing the supplied mixed fluid to flow evenly within the cylindrical housing 11 and fully demonstrate the separation performance of the hollow fiber membranes 12. Furthermore, when the ends of the cylindrical housing 11 and the hollow fiber membranes 12 are bonded and hardened using centrifugal force, the element 1 is laid on its side. At this time, the hollow fiber membranes 12 are densely packed in the direction of gravity, which tends to result in uneven spacing between the hollow fiber membranes 12. In response to this, the spacer 20, which can divide the hollow fiber membranes 12 into a plurality of bundles and store them in the cylindrical housing 11, is effective in arranging the hollow fiber membranes 12 evenly.

[0025] In this case, there is no limitation on the combination of the partition plates 22 that constitute the spacer 20, and the partition plates 22 may be arranged radially from the axial center as shown in Fig. 4(a). Alternatively, the radially arranged partition plates 22 may be further connected to the cylindrical housing by partition plates 22 that are concentric with the cylindrical housing as shown in Fig. 4(b). Alternatively, the partition plates 22 may be arranged in a lattice pattern as shown in Fig. 4(c). As described above, the spacer 20 preferably has a shape that divides the radial cross section inside the cylindrical housing 11 into a plurality of regions, including polygonal or sector-shaped regions.

[0026] The width W1 and number of partition plates 22 may be appropriately selected depending on the material of the spacer 20, the supply pressure of the mixed fluid, and the like. Here, if the width W1 of the partition plates 22 is too large or the number of partition plates 22 is too large, the area around the spacer 20 into which the hollow fiber membranes 12 can be inserted becomes smaller than the area inside the cylindrical housing 11. As a result, the hollow fiber membranes 12 become densely packed, making the hollow fiber membranes 12 more susceptible to damage due to the load acting on the hollow fiber membranes 12 when inserted into the cylindrical housing 11. To prevent damage to the hollow fiber membranes 12, it is preferable to design the area at the end of the cylindrical housing 11 into which the hollow fiber membranes 12 can be inserted, so that the ratio of the area into which the hollow fiber membranes 12 can be inserted when the spacers 20 are not enclosed in the upper potting portion 13(a) is 90% or more, and more preferably 95% or more.

[0027] The axial height H1 of the partition plate 22 constituting the spacer 20 may be set appropriately within a range in which the lower end 24 of the spacer 20 is not exposed from the upper potting portion 13(a), depending on the material of the spacer 20, the supply pressure of the mixed fluid, etc. Here, from the viewpoint of durability against peeling or breakage of the upper potting portion 13(a) from the cylindrical casing 11, the height H1 is preferably 5 mm or more, and more preferably 10 mm or more.

[0028] The material of the spacer 20 may be selected appropriately depending on the supply pressure of the mixed fluid to be supplied and the material of the adhesive resin used to form the upper potting portion 13(a). Examples of suitable materials include fluororesins such as polysulfone resins, polytetrafluoroethylene, and perfluoroalkoxy fluororesins, polycarbonate, polypropylene, polymethylpentene, polyphenylene sulfide, and polyether ketone, as well as reinforced resins obtained by mixing these resin materials with glass fiber, carbon fiber, talc, and the like, and metal materials such as stainless steel and aluminum. From among these materials, it is preferable to select a material that has a bending strength at least equal to or greater than that of the adhesive resin used to form the upper potting portion 13(a).

[0029] FIG. 5 shows another example of the spacer 20 different from the embodiment shown in FIG. 4 . As shown in the top view of the element 1 in FIG. 5 , the spacer 20 may be composed of an outer frame 21 and partition plates 22 that divide the interior of the outer frame 21 into multiple regions. This connects the partition plates 22 together via the outer frame 21, increasing their beam strength. This allows the spacer 20 to achieve even greater strength against separation or breakage of the upper potting portion 13(a) from the cylindrical housing 11. In this case, the width W2 of the outer frame 21 and the axial height H2 shown in FIG. 8 may be appropriately set depending on the material of the spacer, the supply pressure of the mixed fluid, the axial height of the upper potting portion 13(a), and the like, but may also be designed to match the preferred shape of the partition plates 22.

[0030] 2, the outer frame 21 is completely enclosed within the holding portion 17, maximizing the area in which the hollow fiber membranes 12 can be inserted around the spacer 20. In order to prevent the spacer 20 installed in the holding portion 17 from shifting in the radial direction, the outer diameter D2 of the outer frame 21 shown in Fig. 5 is preferably equal to the inner diameter D4 of the holding portion 17 shown in Fig. 2.

[0031] Furthermore, the membrane filling rate of the hollow fiber membranes 12 inserted into the cylindrical housing 11 is preferably 30% or more and 65% or less. When the membrane filling rate is less than 30%, the hollow fiber membranes 12 around the spacer 20 are not densely packed, allowing the hollow fiber membranes 12 to be inserted into the cylindrical housing 11 with a low load. On the other hand, the membrane area per unit volume is small, which may prevent the desired membrane separation performance from being achieved. Therefore, a membrane filling rate of 30% or more is preferable. When fabricating an element 1 with a membrane filling rate of 30% or more, it is more preferable to appropriately shape the spacer 20 or install a holding portion 17, as described above. On the other hand, when the membrane filling rate is greater than 65%, the membrane area per unit volume is large, but the hollow fiber membranes 12 are densely packed, which may result in a large load being applied to the hollow fiber membranes 12 when they are inserted into the cylindrical housing 11, potentially causing damage to the hollow fiber membranes 12. Furthermore, the flow of the mixed fluid during filtration operation may cause contact between the peripheral hollow fiber membranes 12, resulting in scratches on the membrane surfaces and a deterioration in membrane separation performance. Furthermore, the flow area of ​​the mixed fluid within the element 1 is reduced, resulting in an increase in pressure loss. Because these factors tend to deteriorate membrane separation performance, it is preferable that the membrane filling rate be 65% or less.

[0032] Next, an example of the configuration of a module 10 according to an embodiment of the present invention will be described using the schematic cross-sectional view shown in Fig. 6. The module 10 is composed of the aforementioned element 1 and a cap 14 arranged to hermetically seal the end of the element 1. Note that the module 10 shown in Fig. 6 is an example composed only of the element 1 having the discharge nozzle 33 and the cap 14, and does not limit the present invention in any way as long as the end of the element 1 is hermetically sealed by the cap 14, regardless of whether or not other components are present.

[0033] The caps 14 are connected to both ends of the cylindrical casing 11. In the cap 14 shown in Figure 6, the lower cap 14(b) is connected to the lower end of the cylindrical casing 11 and has a supply port 30 for supplying the mixed fluid. The upper cap 14(a) is connected to the upper end of the cylindrical casing 11 and has a permeated fluid discharge port 32 for discharging the permeated fluid. There are no limitations on the method of connecting the cap 14 and the cylindrical casing 11, and they may be fastened by providing a threaded portion at each end, or may be clamped by providing a ferrule structure as shown in Figure 6, so long as the connection is hermetically sealed.

[0034] The material of the cap 14 may be selected appropriately depending on the components contained in the mixed fluid to be supplied and the supply pressure of the mixed fluid, but unless there is a special reason, the same material as that of the cylindrical housing 11 may be used.

[0035] Next, a filtration operation method for the module 10 according to the embodiment of the present invention will be described with reference to Fig. 6. Note that the filtration operation method described below is a filtration operation method based on the module 10 shown in Fig. 6, and does not limit the present invention in any way.

[0036] The module 10 shown in Figure 6 is operated by a cross-flow filtration method using the element 1. The mixed fluid is supplied from the supply port 30 into the cylindrical housing 11 through the through-hole 15 provided in the lower potting part 13(b). The supplied mixed fluid is separated into a permeated fluid and a non-permeated fluid by the hollow fiber membrane 12. The permeated fluid passes through the hollow part of the hollow fiber membrane 12, is collected in the upper cap 14(a), and is discharged to the outside of the module 10 through the permeated fluid discharge port 32. Meanwhile, the non-permeated fluid continues to flow within the cylindrical housing 11, passes through the discharge nozzle 33, and is discharged to the outside of the module 10 through the non-permeated fluid discharge port 31.

[0037] At this time, when a high-pressure mixed fluid is supplied into the module 10, as in the case of the element 1, a large pressure difference occurs between the inside of the cylindrical housing 11 and the inside of the upper cap 14(a), and a large pressure is applied to the upper potting part 13(a) in the upward direction of the module 10. This pressure causes slight deformation of the upper potting part 13(a), and local stress greater than the adhesive force is generated on the bonding surface between the cylindrical housing 11 and the upper potting part 13(a), or local stress greater than the allowable stress of the resin that makes up the upper potting part 13(a). As a result, the upper potting part 13(a) may peel off from the cylindrical housing 11 or may be damaged.

[0038] To address the above-mentioned issues, the element 1 includes the lower end 24 of the spacer 20 within the upper potting portion 13(a), thereby suppressing the generation of local stress due to minute deformation of the upper potting portion 13(a) and preventing the upper potting portion 13(a) from peeling off or breaking from the cylindrical housing 11. On the other hand, the adhesive strength between the cylindrical housing 11 and the upper potting portion 13(a) is small, and the upper potting portion 13(a) may peel off or break from the cylindrical housing 11 at a pressure lower than that which causes minute deformation of the upper potting portion 13(a).

[0039] Therefore, to prevent the upper potting portion 13(a) from peeling off or being damaged from the cylindrical housing 11, it is preferable to directly contact the tip of the protrusion 16 provided on the inner wall of the upper cap 14(a) with the upper end portion 23 of the spacer 20, as shown in FIG. 6 . By contacting the spacer 20 with the upper cap 14(a) via the protrusion 16, the upper cap 14(a) supports the pressure applied to the upper potting portion 13(a), thereby suppressing minute deformation of the upper potting portion 13(a). This reduces local stress generated at the adhesive surface between the cylindrical housing 11 and the upper potting portion 13(a), thereby preventing the upper potting portion 13(a) from peeling off or being damaged from the cylindrical housing 11. Furthermore, similar to the element 1 shown in FIG. 1 , the upper end portion 23 of the spacer 20 is exposed from the upper potting portion 13(a). Therefore, even if the upper potting part 13(a) is cut to open the end of the hollow fiber membrane 12, the dimension from the upper end 23 of the spacer 20 exposed from the upper potting part 13(a) to the end of the cylindrical housing 11 can always be constant regardless of the cutting accuracy. This allows the protrusions 16 of the upper cap 14(a) to come into contact with the upper end 23 of the spacer 20 with high precision when the upper cap 14(a) and the cylindrical housing 11 are hermetically sealed. In this case, the protrusions 16 of the upper cap 14(a) may come into contact with the upper end 23 at one location or over the entire area. However, it is preferable to maximize the contact area by appropriately selecting the shape and number of the protrusions 16 so that the pressure received from the upper potting part 13(a) can be dispersed.

[0040] Next, using the schematic cross-sectional view of the module 10 shown in FIG. 7 , a case where the upper end 23 of the spacer 20 is enclosed in the upper potting part 13(a) in the same manner as the lower end 24 will be described. When the upper end 23 of the spacer 20 is enclosed in the upper potting part 13(a), an uncut potting part 25 is formed in the region on the upper cap 14(a) side of the spacer 20 when projected in the axial direction. At this time, the interior of the uncut potting part 25 is blocked by the spacer 20 and no hollow fiber membranes 12 are present, so the uncut potting part 25 does not require cutting to open the ends of the hollow fiber membranes 12 as described above. Therefore, when forming the upper potting part 13(a) with an adhesive resin, a potting jig (not shown) can be provided in advance in the region on the upper cap 14(a) side of the spacer 20 when projected in the axial direction, so that the uncut potting part 25 is not formed at the cutting position of the upper potting part 13(a). This allows the dimension from the end of the cylindrical housing 11 to the upper end of the uncut potting portion 25 to be constant regardless of the cutting accuracy, so that the protrusion 16 of the upper cap 14(a) and the upper end 23 of the spacer 20 can come into contact with high precision via the uncut potting portion 25. In this case, the contact point may be one point on the uncut potting portion 25, or the entire uncut potting portion 25. However, it is preferable to make the contact area as large as possible in order to distribute the pressure received from the upper potting portion 13(a).

[0041] Furthermore, the no-cut potting portion 25 must be formed at least in a location that comes into contact with the protrusion 16 of the upper cap 14(a). Depending on the shape of the protrusion 16, the no-cut potting portion 25 may be formed on a portion of the surface of the spacer 20 projected in the axial direction, or may be formed on the entire projected surface. However, in order to increase the contact area between the protrusion 16 of the upper cap 14(a) and the no-cut potting portion 25 and thereby distribute the pressure received from the upper potting portion 13(a), it is preferable that the no-cut potting portion 25 be formed on as much of the projected surface as possible.

[0042] FIG. 8 is a schematic cross-sectional view of a module 10 composed of an element 1 using a spacer 20 having an outer frame 21 shown in FIG. 5 and a cap 14. In a spacer 20 provided with an outer frame 21, as shown in FIG. 8, the only areas in direct contact between the spacer 20 and the upper cap 14(a) are the outer frame 21 of the spacer 20 and the axial end of the upper cap 14(a) on the cylindrical housing 11 side. This is because even if only the outer frame 21 is in contact with the end of the upper cap 14(a), the partition plate 22 within the outer frame 21 can sufficiently function as a beam, thereby achieving high strength against peeling or breakage of the upper potting portion 13(a) from the cylindrical housing 11. Furthermore, the contact area between the upper cap 14(a) and the outer frame 21 may be a part of or the entire outer frame 21. However, in order to distribute the pressure received from the upper potting portion 13(a), the contact area is preferably the entire outer frame 21. As shown in Figure 7, the same effect can be achieved by enclosing the upper end 23 of the spacer 20, which has an outer frame 21, within the upper potting portion 13(a), and bringing the outer frame 21 of the spacer 20 into contact with the axial end of the upper cap 14(a) on the cylindrical housing 11 side via the uncut potting portion 25.

[0043] Furthermore, since the only contact point is the outer frame 21, there is an advantage that the upper cap 14(a) can be easily manufactured. This is because there is no need to provide protrusions 16 on the inner wall of the upper cap 14(a). Furthermore, since the only contact point is the outer frame 21, there is an advantage that the upper potting part 13(a) can also be easily formed. This is because, when forming the upper potting part 13(a), the area obtained by projecting the spacer 20 in the axial direction other than the outer frame 21 is not included in the contact point, so the end of the upper potting part 13(a) can be cut off as excess, together with the area where the hollow fiber membranes 12 are present, without having to consider cutting accuracy.

[0044] 9, the module 10 may have a retaining portion 17 at the end of the cylindrical housing 11, with the spacer 20 mounted on the retaining portion 17, and the upper end 23 of the spacer 20 in direct contact with the upper cap 14(a). Alternatively, as shown in the schematic cross-sectional view of FIG. 10, the module 10 may have the upper end 23 of the spacer 20 mounted on the retaining portion 17 enclosed in the upper potting portion 13(a), with the upper cap 14(a) in contact with the upper end 23 of the spacer 20 via the uncut potting portion 25. FIG. 11 is a top view of the module 10 with the spacer 20 comprised only of a partition plate 22 mounted on the retaining portion 17 and the upper cap 14(a) removed. As shown in FIG. 11, by forming a groove as the retaining portion 17 appropriately conforming to the shape of the spacer 20 and holding the spacer 20 in the retaining portion 17, it is possible to prevent the spacer 20 from shifting in the axial and radial directions during adhesive curing. In this case, the spacer 20 does not need to have an outer frame 21, as shown in FIG. 11 . Furthermore, similar to the embodiment shown in FIGS. 9 and 10 , the upper end 23 of the spacer 20 located in the region restrained by the retaining portion 17 can be brought into contact with the upper cap 14(a) directly or via the uncut potting portion 25, thereby achieving high strength against peeling or breakage of the upper potting portion 13(a) from the cylindrical housing 11. This is because, regardless of the shape of the spacer 20, the partition plate 22 can function sufficiently as a beam as long as the region restrained by the retaining portion 17 is brought into contact. In this case, there is no need to provide a protrusion 16 on the inner wall of the upper cap 14(a), which facilitates the manufacture of the upper cap 14(a) and the formation of the upper potting portion 13(a), similar to the embodiment shown in FIGS. 9 and 10 .

[0045] Furthermore, the module 10 according to the embodiment of the present invention shown in Figure 6 and elsewhere is an example composed only of an element 1 having an outlet nozzle 33 and a cap 14, and may be configured such that the end of the element 1 is hermetically sealed by the cap 14 and the non-permeated fluid can be recovered from the non-permeated fluid recovery port 35. For example, the module 10 using the element 1 shown in Figure 1 does not have an outlet nozzle 33, but may be configured such that the end of the element 1 is hermetically sealed by the cap 14 and the non-permeated fluid can be recovered from the non-permeated fluid recovery port 35. Furthermore, as shown in the schematic cross-sectional view of Figure 12(a), the module 10 may be stored inside a separately prepared storage container 34, both ends of which are hermetically sealed by storage container lids 36, and the non-permeated fluid may be recovered from the non-permeated fluid recovery port 35 provided in the storage container lid 36. In this case, one or more sets of modules 10 may be stored in the storage container 34. Furthermore, since the module 10 is configured so that the end of the element 1 is hermetically sealed by the cap 14, the module 10 may be configured so that the element 1 is stored in a storage container 34 as shown in Figure 12 (b), and the storage container lid 36 is hermetically sealed to the end of the element 1 as a substitute for the cap 14.

[0046] As described above, the element 1 and module 10 of the present invention have extremely high resistance to peeling or breakage of the upper potting portion 13(a) from the cylindrical housing 11. Therefore, a suitable operating method using these elements is to supply a mixed fluid into the element 1 at high pressure and separate the mixed fluid. In this case, the pressure of the mixed fluid supplied to the element 1 is preferably 1 MPa or more and 30 MPa or less. Within this pressure range, it is preferable to select an appropriate material for the hollow fiber membrane 12 taking into account the operating pressure and its diameter so that the hollow fiber membrane 12 is not damaged by the pressure difference between its outside and inside or the flow path of the permeating fluid is not blocked due to deformation. For example, under relatively low-pressure conditions within the aforementioned range, hollow fiber membranes 12 made of polymeric materials such as fluorine-based resins and polysulfone-based resins can be selected. Furthermore, under high-pressure conditions where hollow fiber membranes 12 made of polymeric materials may be damaged, hollow fiber membranes 12 made of inorganic materials such as carbon and zeolite can be selected. On the other hand, since the upper limit of pressure resistance of hollow fiber membranes 12 made of these materials is approximately 30 MPa or less, it is preferable that the pressure of the fluid to be supplied be 30 MPa or less.

[0047] Furthermore, the element 1 or module 10 of the present invention can be applied to various mixed fluid filtration operation methods and is particularly suitable when the mixed fluid to be supplied is a gas, because gas is an incompressible fluid and its pressure can be relatively easily increased to several MPa, and in membrane separation, the higher the pressure of the supplied fluid, the more improved the membrane separation performance.

[0048] This is also suitable when the viscosity of the mixed fluid to be supplied is high. When the mixed fluid has a high viscosity, the pressure loss during flow through the element 1 is large, and it is necessary to operate the element at high pressure during transportation. Therefore, it is preferable to use this element for mixed fluids whose viscosity during filtration operation is 2 mPa s or more.

[0049] Although there are no particular limitations on the method for measuring viscosity, when the mixed fluid is a liquid, the viscosity may change depending on the shear rate. In this case, it is preferable to measure the shear viscosity at the shear rate during filtration operation. Specifically, by using a rheometer, the shear viscosity when the shear rate during filtration operation is applied can be measured.

[0050] This method is also suitable when the turbidity of the mixed fluid being fed is high. When the mixed fluid is highly turbid, turbid matter is likely to accumulate on the surface of the hollow fiber membrane 12. The accumulation of turbid matter blocks the pores on the membrane surface, thereby reducing membrane separation performance. For this reason, filtration operation may be performed in a manner that prevents turbid matter from accumulating on the membrane surface by increasing the feed flow rate and increasing the flow rate of the mixed fluid on the membrane surface. In this case, the high flow rate within the element 1 results in a large pressure loss, making it necessary to operate at high pressure during transportation. Therefore, this method is preferably applied to mixed fluids with a turbidity of 20 NTU or more and a total organic carbon (TOC) concentration of 1000 mg / L or more.

[0051] There are no particular limitations on the method for measuring turbidity as long as the value is measured in units of NTU (Nephelometric Turbidity Unit), and when the mixed fluid is a liquid, it can be measured using various measuring devices.

[0052] Furthermore, when the mixed fluid is a liquid, the TOC concentration can be measured using the TC-IC method, which calculates the TOC concentration by subtracting inorganic carbon (IC) from total carbon (TC), or the NPOC method, which adds acid to a sample, aerates it, and then measures the total carbon in the liquid after aeration to calculate the TOC concentration. When the mixed fluid contains a large amount of volatile organic carbon, it is preferable to use the TC-IC method for measurement.

[0053] In addition to the above, since the viscosity and turbidity values ​​change depending on the temperature, it is preferable to measure the viscosity and turbidity at the temperature during filtration operation.

[0054] The purification facility of the present invention includes the above-described element 1 or module 10. The purification facility preferably includes, in addition to the element 1 or module 10, a pretreatment facility, a purified fluid recovery facility, a by-product fluid recovery facility, and the like. The pretreatment facility is a facility for removing impurities from the mixed fluid before separation and adjusting the composition of the mixed fluid before separation. The purified fluid recovery facility is a facility for recovering a purified fluid from which unnecessary components have been removed from the mixed fluid, further purifying the purified fluid as necessary, and supplying the purified fluid to a pipeline or the like. The by-product fluid recovery facility is a facility for recovering a by-product fluid from the mixed fluid after the purified fluid has been removed, and may include a facility for detoxifying the by-product fluid and discharging it. In the purification facility of the present invention, the element 1 or module 10, the pretreatment facility, the purified fluid recovery facility, and the by-product fluid recovery facility are preferably connected by piping or the like, and the mixed fluid is continuously separated into the purified fluid and the by-product fluid.

[0055] In the purification equipment of the present invention, the mixed fluid to be separated is not particularly limited, but is preferably a mixed fluid that requires a large throughput per hour and is supplied at high pressure. When the mixed fluid is a gas, examples of applications include carbon dioxide separation and storage systems from exhaust gases from power plants, blast furnaces, etc., purification of biogas or natural gas, and purification of purified gas after steam methane reforming. When the mixed fluid is a liquid, examples of applications include separation of high-viscosity and high-turbidity mixed fluids in fields such as fermentation involving the cultivation of microorganisms or cultured cells, or the food industry, for example, to separate microorganisms or cultured cells, or purification of specific components (proteins, sugars, etc.) contained in the mixed fluid.

[0056] The purification method of the present invention is a purification method in which a mixed fluid to be separated is supplied to the above-mentioned purification equipment, and one component to be purified is separated and purified from the mixed fluid via a hollow fiber membrane 12 included in an element 1 or a module 10 included in the purification equipment, and discharged from the purification equipment. In this case, the one component to be purified may be discharged as either a permeated fluid or a non-permeated fluid.

[0057] DESCRIPTION OF SYMBOLS 10 Module 11 Cylindrical housing 12 Hollow fiber membrane 13 (a) Upper potting part 13 (b) Lower potting part 14 (a) Upper cap 14 (b) Lower cap 15 Through hole 16 Protrusion 17 Holding part 20 Spacer 21 Outer frame 22 Partition plate 23 Upper end part of spacer 20 24 Lower end part of spacer 20 25 Uncut potting part 26 Insertion groove 27 Fixing groove 30 Supply port 31 Non-permeated fluid discharge port 32 Permeated fluid discharge port 33 Discharge nozzle 34 Storage container 35 Non-permeated fluid recovery port 36 Storage container lid W1 Width of partition plate 22 W2 Width of outer frame 21 H1 Axial height of partition plate 22 H2 Axial height of outer frame 21 H3 Axial height of holding part 17 D1 Inner diameter of outer frame 21 D2 Outer diameter of outer frame 21 D3 Inner diameter of cylindrical housing 11 D4 Inner diameter of holding portion 17

Claims

1. A hollow fiber membrane element comprising: a plurality of hollow fiber membranes inserted into a cylindrical casing; a potting section at least on one end side of the cylindrical casing where the hollow fiber membranes and the cylindrical casing are integrated by bonding; and a spacer that divides the radial cross section inside the cylindrical casing into a plurality of regions, characterized in that the end of the spacer in the axial direction of the cylindrical casing where the outer surface of the hollow fiber membranes is exposed is enclosed within the potting section.

2. The hollow fiber membrane element according to claim 1, characterized in that a holding portion for holding the spacer is provided at the end of the cylindrical housing.

3. The hollow fiber membrane element according to claim 1 or 2, wherein the spacer is fixed in the axial direction within the cylindrical housing.

4. A hollow fiber membrane element according to claim 1 or 3, characterized in that the spacer is fixed in the axial direction by fitting the spacer into the inner wall of the cylindrical housing.

5. The hollow fiber membrane element according to claim 2 or 3, wherein the spacer is fixed in the axial direction by fitting the holding portion into the spacer.

6. A hollow fiber membrane element according to any one of claims 1 to 5, characterized in that the spacer divides the radial cross section of the interior of the cylindrical housing into a plurality of regions, including polygonal or sectoral shapes.

7. A hollow fiber membrane element according to any one of claims 1 to 6, wherein the axial height of the spacer is 5 mm or more.

8. A hollow fiber membrane element according to any one of claims 1 to 7, characterized in that the spacer is composed of an outer frame and partition plates that divide the inside of the outer frame into a plurality of regions.

9. A hollow fiber membrane element according to any one of claims 1 to 8, wherein the spacer is made of a material having a bending strength equal to or greater than that of the adhesive resin used to form the potting portion.

10. A hollow fiber membrane element according to any one of claims 1 to 9, characterized in that the membrane filling rate of the hollow fiber membranes inserted into the cylindrical casing is 30% or more and 65% or less.

11. An external pressure type hollow fiber membrane module comprising a hollow fiber membrane element according to any one of claims 1 to 10 and a cap arranged to hermetically seal the end of the hollow fiber membrane element, characterized in that one end of the spacer contacts the cap directly or via a potting section within the area where the spacer is projected in the axial direction of the cylindrical casing.

12. An external pressure type hollow fiber membrane module as described in claim 11, characterized in that the means for bringing one end of the spacer into contact with the cap directly or via a potting section within the area projected in the axial direction of the cylindrical casing is a protrusion provided on the inner wall of the cap.

13. An external pressure type hollow fiber membrane module according to claim 11 or 12, characterized in that the only point of contact between the spacer and the cap, either directly or via the potting portion, is the outer frame of the spacer.

14. A method for operating a hollow fiber membrane element or an external pressure type hollow fiber membrane module, comprising separating a mixed fluid using the hollow fiber membrane element or external pressure type hollow fiber membrane module according to any one of claims 1 to 13, with the mixed fluid supply pressure being 1 MPa or more and 30 MPa or less.

15. The method for operating a hollow fiber membrane element or an external pressure type hollow fiber membrane module according to claim 14, wherein the mixed fluid is a gas.

16. A method for operating a hollow fiber membrane element or an external pressure type hollow fiber membrane module according to claim 14, wherein the viscosity of the mixed fluid is 2 mPa·s or more.

17. A method for operating a hollow fiber membrane element or an external pressure type hollow fiber membrane module according to claim 14 or 16, characterized in that the turbidity of the mixed fluid is 20 NTU or more and the TOC concentration is 1000 mg / L or more.

18. A purification facility comprising the hollow fiber membrane element or external pressure type hollow fiber membrane module according to any one of claims 1 to 13.

19. A biogas or natural gas purification facility comprising the hollow fiber membrane element or external pressure type hollow fiber membrane module according to any one of claims 1 to 13.

20. A purification method for separating and purifying one component from a mixed fluid using the purification equipment described in claim 18 or 19.

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