Hollow fiber membrane module

Abstract

This invention provides a hollow fiber membrane module. The hollow fiber membrane module (100) includes: a plurality of hollow fiber membranes (10); a container (20) housing the plurality of hollow fiber membranes (10); and a water supply inlet (201) disposed at one end of the container (20) such that the direction of water flow into the interior of the container (20) is parallel to the longitudinal direction of the plurality of hollow fiber membranes (10). The permeate flux of the hollow fiber membranes (10) at an intermembrane pressure difference of 0.1 MPa is 850 liters / m³. 2 / h or more.

Description

Technical Field

[0001] This invention relates to a hollow fiber membrane module. Background Technology

[0002] In the manufacture of semiconductor devices, a large quantity of ultrapure water is indispensable. Ultrapure water can be produced using a water treatment system equipped with hollow fiber membrane modules. These modules are positioned at designated locations within the water treatment system and primarily contribute to the removal of fine particles that pose a significant obstacle to semiconductor device manufacturing.

[0003] Hollow fiber membrane modules are sometimes cleaned to remove fouling, fine particles adhering to the surface of the hollow fiber membrane, and fine particles accumulated inside the container. Cleaning is performed, for example, periodically.

[0004] Patent Document 1 discloses an external pressure type hollow fiber membrane module with a turbulent flow member for permeate fluid located near the outlet end of the hollow fiber membrane. Patent Document 2 discloses a backwashing method for a hollow fiber membrane module.

[0005] Patent Document 1: Japanese Patent Application Publication No. 5-137972

[0006] Patent Document 2: Japanese Patent Application Publication No. 2016-179430 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] During the cleaning process of hollow fiber membrane modules, the supply of ultrapure water from the modules is stopped. Therefore, it is desirable to minimize the cleaning time. One method to shorten the cleaning time is to increase the flow rate of the cleaning solution. However, increasing the flow rate also increases the likelihood of damage to the hollow fiber membrane.

[0009] The purpose of this invention is to prevent damage to hollow fiber membranes and to shorten the time required for cleaning hollow fiber membrane modules.

[0010] Solution for solving the problem

[0011] This invention provides a hollow fiber membrane module, which is an externally pressurized hollow fiber membrane module, wherein,

[0012] The hollow fiber membrane module includes:

[0013] Multiple hollow fiber membranes;

[0014] A container that houses the plurality of hollow fiber membranes; and

[0015] A water supply inlet is located at one end of the container such that the direction of water inflow into the container is parallel to the longitudinal direction of the plurality of hollow fiber membranes.

[0016] The permeation flux of the hollow fiber membrane at a membrane pressure difference of 0.1 MPa is 850 L / m³. 2 / h or more.

[0017] The effects of the invention

[0018] The hollow fiber membrane module of the present invention can prevent damage to the hollow fiber membrane and be thoroughly cleaned in a short time. Attached Figure Description

[0019] Figure 1 This is a longitudinal sectional view of a hollow fiber membrane assembly according to an embodiment of the present invention.

[0020] Figure 2 These are the top view and sectional view of the partition.

[0021] Figure 3A It is a 3D diagram of the inner and outer mesh layers.

[0022] Figure 3B It is a diagram showing the positional relationship between the inner and outer nets.

[0023] Figure 3C This is a diagram that represents another positional relationship between the inner and outer nets.

[0024] Figure 4 This diagram illustrates the problems that arise when the direction of water inflow is perpendicular to the length of the hollow fiber membrane.

[0025] Figure 5 This is a structural diagram of an example of a water treatment system that uses hollow fiber membrane modules.

[0026] Figure 6 It is a chart representing the results of the cleaning test. Detailed Implementation

[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the following embodiments.

[0028] Figure 1This is a longitudinal sectional view of a hollow fiber membrane module 100 according to one embodiment of the present invention. The hollow fiber membrane module 100 includes a container 20 and a plurality of hollow fiber membranes 10. The hollow fiber membrane module 100 is an external pressure type hollow fiber membrane module. "External pressure type" means that the supply water flows outside the hollow fiber membrane 10 and the permeate flows inside the hollow fiber membrane 10. In this embodiment, the supply water is water to be treated. The permeate is ultrapure water. The hollow fiber membrane module 100 is used, for example, to produce ultrapure water.

[0029] Container 20 is a component for housing multiple hollow fiber membranes 10. Container 20 is provided with a water supply inlet 201, a permeate outlet 202, and a concentrate outlet 203. The water supply inlet 201 is located at one end of container 20 such that the direction of water flow into the interior of container 20 is parallel to the longitudinal direction of the multiple hollow fiber membranes 10. This configuration prevents direct collision between the water supply and the hollow fiber membranes 10 from a direction perpendicular to their longitudinal direction. Therefore, the hollow fiber membranes 10 are less prone to damage.

[0030] The permeate outlet 202 is located at the other end of the container 20, with the direction of permeate flow to the outside of the container 20 parallel to the longitudinal direction of the plurality of hollow fiber membranes 10. The concentrate outlet 203 is located at the other end of the container 20, with the direction of water supply from the inside of the container 20 to the outside perpendicular to the longitudinal direction of the plurality of hollow fiber membranes 10. This configuration also contributes to the aforementioned effects.

[0031] Container 20 includes a container body 20a, a cover 20b, and a cover 20c. The container body 20a is a cylindrical component open at both ends. The covers 20b and 20c are funnel-shaped components installed at one end and the other end of the container body 20a, respectively. The covers 20b and 20c are detachable from the container body 20a. The covers 20b and container body 20a are fixed together using bolts, screws, or other fastening components. Similarly, the covers 20c and container body 20a are fixed together using bolts, screws, or other fastening components. A water supply inlet 201 is located at the opening of the cover 20b. A permeate outlet 202 is located at the opening of the cover 20c. A concentrated water outlet 203 is located at the opening of the container body 20a. Piping, connectors, and other components can be connected to the water supply inlet 201, the permeate outlet 202, and the concentrated water outlet 203.

[0032] In the hollow fiber membrane module 100, the container 20 has three openings: a supply water inlet 201, a permeate outlet 202, and a concentrate outlet 203. Compared to a container with four openings, the hollow fiber membrane module 100 has fewer piping connections. This contributes to the simplification and cost reduction of the water treatment system incorporating the hollow fiber membrane module 100.

[0033] Inside the container 20 are internal spaces SP1, SP2, and SP3 that function as flow paths. Internal space SP1 is the internal space of the container body 20a and functions as a water supply path. Internal space SP2 is the internal space of the cover 20b and functions as a water supply path. Internal space SP3 is the internal space of the cover 20c and functions as a permeate flow path. Multiple hollow fiber membranes 10 open toward the internal space SP3. Permeate is delivered from the hollow fiber membranes 10 to the outside of the hollow fiber membrane assembly 100 via the internal space SP3 of the cover 20c.

[0034] There are no special restrictions on the material of container 20. Container 20 can be made of resins such as vinyl chloride, polycarbonate, and polysulfone.

[0035] Multiple hollow fiber membranes 10 are arranged parallel to each other. The longitudinal direction of the hollow fiber membranes 10 is parallel to the longitudinal direction of the container 20. Examples of hollow fiber membranes 10 include microfiltration membranes, ultrafiltration membranes, and reverse osmosis membranes. Typically, the hollow fiber membranes 10 are ultrafiltration membranes. The number, size, and material of the hollow fiber membranes 10 are not particularly limited. The number of hollow fiber membranes 10 is, for example, 1,000 to 20,000. The outer diameter of the hollow fiber membranes 10 is, for example, 0.2 to 2.0 mm. The length of the hollow fiber membranes 10 is, for example, 800 to 1,200 mm. Examples of materials for the hollow fiber membranes 10 include polysulfone, polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, polyvinyl chloride-polyacrylonitrile copolymer, polyamide, and cellulose acetate.

[0036] When the hollow fiber membrane 10 is made of an ultrafiltration membrane, its molecular weight cutoff is, for example, in the range of 1,000 to 500,000. The term "molecular weight cutoff" means the approximate molecular weight of low-concentration globular solutes (typically protein molecules) that can be blocked by the membrane of the object by more than 90%.

[0037] Typically, the hollow fiber membrane 10 has skin layers on both the inner and outer surface sides. A sponge layer exists between the skin layers. The sponge layer is a porous layer with a lower density than the skin layers. This structure is also called a double-skin structure. Because the supplied water is filtered twice by the two skin layers, a high rejection rate can be achieved with the hollow fiber membrane 10 having a double-skin structure. Even if there are defects in the skin layer on the outer surface side, as long as the skin layer on the inner surface side is normal, fine particles and the like can be prevented from mixing into the permeate water. Furthermore, the skin layer can exist only on the inner surface side or only on the outer surface side.

[0038] The hollow fiber membrane assembly 100 also includes a binding portion 12 and a binding portion 14. For convenience, the binding portion 12 is referred to as "first binding portion 12". The binding portion 14 is referred to as "second binding portion 14". A plurality of hollow fiber membranes 10 are bound together using the first binding portion 12 and the second binding portion 14. The first binding portion 12 is located at one end of the plurality of hollow fiber membranes 10. One end of the plurality of hollow fiber membranes 10 is sealed by the first binding portion 12. The second binding portion 14 is located at the other end of the plurality of hollow fiber membranes 10. The other end of the plurality of hollow fiber membranes 10 is open at the end face 14p of the second binding portion 14. The plurality of hollow fiber membranes 10, the first binding portion 12, and the second binding portion 14 form a membrane bundle.

[0039] The binding portions 12 and 14 are formed, for example, by injection molding. In this case, the binding portions 12 and 14 are also referred to as injection-molded portions. The binding portions 12 and 14 can be made of resin filled between the hollow fiber membranes 10 and 10. Examples of resins constituting the binding portions 12 and 14 include epoxy resin and polyurethane resin.

[0040] A gap is provided between the first binding part 12 and the inner surface of the container 20, allowing supply water to pass through. The second binding part 14 separates the internal space SP1, which serves as the supply water flow path, from the internal space SP3, which serves as the permeate water flow path, inside the container 20. The second binding part 14 is fixed to the container body 20a or the cover 20c. With this configuration, mixing of supply water and permeate water can be prevented, achieving a high rejection rate. The gap between the first binding part 12 and the inner surface of the container 20 can also exist within a 360-degree radius around the first binding part 12.

[0041] In this embodiment, the second binding portion 14 is fixed to the cover 20c using an adhesive. The cover 20c is integrated with the second binding portion 14 and is installed at the other end of the container body 20a. The hollow fiber membrane 10, the second binding portion 14, and the cover 20c form a unit 70. The unit 70 can be removed from the container body 20a in a non-destructive manner. That is, the removal of the unit 70 from the container body 20a and the installation of the unit 70 onto the container body 20a are completed while maintaining the integration of the second binding portion 14 and the cover 20c. This structure helps to reduce the wall area of ​​the permeable water flow path and suppress dust generation.

[0042] Fine particles are believed to be physically adsorbed onto the walls of the permeate flow path and gradually detached from the walls as the permeate flows. The walls of the permeate flow path include the inner surface of the hollow fiber membrane 10, the surface of the second binding portion 14, and the inner surface of the cover 20c. By minimizing the surface area of ​​the second binding portion 14 and the inner surface area of ​​the cover 20c, the adsorption sites for fine particles can be reduced. From the viewpoint of reducing the adsorption sites for fine particles, the construction of fixing the second binding portion 14 to the cover 20c is advantageous.

[0043] Furthermore, the unit 70 can be detached from the container body 20a to clean or repair the hollow fiber membrane 10 and / or the second binding portion 14, and then the unit 70 can be installed back onto the container body 20a. Alternatively, a new unit 70 can be installed onto the container body 20a. In other words, the hollow fiber membrane assembly 100 according to this embodiment allows for quick and easy cleaning, replacement, or repair of the hollow fiber membrane 10 and / or the second binding portion 14. When the hollow fiber membrane 10 is detached from the container body 20a, the components are not damaged, thus reducing component costs.

[0044] In the hollow fiber membrane module 100 of this embodiment, there are no other components between the second binding portion 14 and the cover 20c. Typically, the other components are sealing rings. Furthermore, there is no groove for the sealing ring to be inserted between the second binding portion 14 and the cover 20c. That is, there is no groove for the sealing ring to be inserted on either the surface of the second binding portion 14 facing the cover 20c or the surface of the cover 20c facing the second binding portion 14. With this structure, liquid accumulation is unlikely to form or will not form between the second binding portion 14 and the cover 20c. In other words, liquids such as permeate are unlikely to accumulate or will not accumulate between the second binding portion 14 and the cover 20c. Fine particles and other contaminants are unlikely to accumulate or will not accumulate between the second binding portion 14 and the cover 20c. Therefore, the hollow fiber membrane module 100 can be easily cleaned without disassembly.

[0045] In this specification, "integrated" means that the components cannot be separated from each other in a non-destructive manner. "Non-destructive" means that separation and assembly can be performed reversibly. For example, the separation of components fixed with adhesives is not included in the concept of non-destructive.

[0046] The hollow fiber membrane module 100 also includes a partition 30. The partition 30 is disposed inside the container 20. Specifically, the partition 30 is disposed between the water supply inlet 201 and one end of the plurality of hollow fiber membranes 10. The partition 30 faces the first binding portion 12. A gap exists between the partition 30 and the first binding portion 12. Figure 2As shown, the partition 30 is, for example, a resin component with a circular plate shape. Multiple through holes 30h are provided circumferentially on the outer periphery of the partition 30. The internal space SP1 of the container body 20a and the internal space SP2 of the cover 20b are connected through the through holes 30h. Water is supplied and flows from the internal space SP2 toward the internal space SP1 through the through holes 30h.

[0047] When supply water is introduced into container 20 from supply water inlet 201, partition 30 prevents the flow of supply water from directly colliding with hollow fiber membrane 10 and first binding portion 12. This prevents damage to hollow fiber membrane 10. In this embodiment, partition 30 is a single plate-shaped component. Alternatively, partition 30 may be formed from multiple plate-shaped components.

[0048] Figure 2 The dashed line shown is the projection line 12L when the first binding portion 12 is projected onto the partition 30 in a direction parallel to the length direction of the hollow fiber membrane 10. In the radial direction of the partition 30, the first binding portion 12 is located closer to the inner side than the outer edge of the partition 30. The projection line 12L of the first binding portion 12 slightly overlaps with the through hole 30h. Alternatively, the projection line 12L of the first binding portion 12 may not overlap with the through hole 30h. With this configuration, the pressure of the supplied water flow can be prevented from affecting the hollow fiber membrane 10 and the first binding portion 12.

[0049] The hollow fiber membrane module 100 also includes an outer mesh 40 and multiple inner meshes 42. Multiple hollow fiber membranes 10 are bound together using the outer mesh 40 and the multiple inner meshes 42. The multiple inner meshes 42 bind the multiple hollow fiber membranes 10 in a bundled manner. The outer mesh 40 binds the multiple inner meshes 42. Based on the double-layer mesh structure including the outer mesh 40 and the multiple inner meshes 42, the rigidity of the bundle of multiple hollow fiber membranes 10 can be improved. In this case, the hollow fiber membranes 10 are less likely to sway in the container 20 due to water flow, and the hollow fiber membranes 10 are less likely to be damaged. In particular, damage to the hollow fiber membranes 10 near the boundary between the hollow fiber membranes 10 and the second binding portion 14 can be prevented. The double-layer mesh structure is one method to enable the supply water or cleaning fluid to flow at a high flow rate.

[0050] Figure 3A This is a three-dimensional view of the outer mesh 40 and the inner mesh 42. Figure 3B This indicates the positional relationship between the inner net 42 and the outer net 40. Figure 3A and Figure 3B In the example shown, multiple hollow fiber membranes 10 are divided into two bundles, each bundle being bound together by an inner mesh 42. The hollow fiber membranes 10 and the two inner meshes 42 are then bound together by an outer mesh 40.

[0051] Figure 3CThis indicates another positional relationship between the inner net 42 and the outer net 40. Figure 3C In the example shown, multiple hollow fiber membranes 10 are divided into four bundles, each bundle being bound together by an inner mesh 42. The hollow fiber membranes 10 and the four inner meshes 42 are then bound together into two bundles by an outer mesh 40.

[0052] The number of outer mesh 40 and inner mesh 42 is not particularly limited. The number of inner mesh 42 can also be three or more. The number of outer mesh 40 can also be two or more. The construction of outer mesh 40 and inner mesh 42 is also not particularly limited. Figures 3A-3C In the example shown, the mesh size of the outer mesh 40 is larger than that of the inner mesh 42. Alternatively, the mesh size of the inner mesh 42 can be larger than that of the outer mesh 40. It is also possible that the mesh size of the inner mesh 42 is the same as that of the outer mesh 40.

[0053] The hollow fiber membrane module 100 of this embodiment can be thoroughly cleaned in a short time. In other words, the hollow fiber membrane module 100 can easily restore its original performance through cleaning. Alternatively, the operating time required for a new hollow fiber membrane module 100 to achieve the required performance is shorter. During the cleaning of the hollow fiber membrane module 100, the cleaning solution is introduced into the interior of the container 20 through the supply water inlet 201 and discharged to the outside of the container 20 through the concentrated water outlet 203. The permeate generated by filtering the cleaning solution is discharged to the outside of the container 20 through the permeate outlet 202. As the cleaning solution, ultrapure water, acids, alkalis, oxidizing liquids, reducing liquids, surfactants, etc., can be used. Typically, the cleaning solution is ultrapure water. "Ultrapure water" refers, for example, pure water with a resistivity of 17 MΩ·cm or higher. The resistivity of pure water or ultrapure water can be measured based on the Japanese Industrial Standard JIS K0552 (1994).

[0054] The hollow fiber membrane module 100 is cleaned by directing the cleaning fluid in a forward direction. "Forward direction" refers to the normal flow direction of water during operation. By performing cleaning only in the forward direction, it is possible to prevent the permeate flow path from being contaminated by fine particles due to the cleaning water.

[0055] It was believed that increasing the flow rate of the cleaning fluid could shorten the cleaning time. In other words, it was thought that a higher flow rate of the cleaning fluid would reduce the time required to remove fine particles and other foreign matter. However, excessively increasing the flow rate of the cleaning fluid could damage the hollow fiber membrane. Therefore, shortening the cleaning time of hollow fiber membrane modules has historically been difficult.

[0056] In particular, as with the hollow fiber membrane module disclosed in Patent Document 2, if the water supply inlet and the concentrated water outlet are located on the side of the container, the hollow fiber membrane is easily damaged if the cleaning fluid flows at a high flow rate.

[0057] Figure 4 The hollow fiber membrane module 300 disclosed in Patent Document 2 is shown schematically. The hollow fiber membrane module 300 has a supply water inlet 303a and a concentrate outlet 303c located on the side of a container 303. Permeate is guided to the outside of the hollow fiber membrane module 300 through permeate outlets 303b located at both ends of the container 303. Injection molding portions 305 are provided at both ends of the hollow fiber membrane 301, which separate the supply water flow path from the permeate water flow path.

[0058] Figure 4 The water supply inlet 303a of the hollow fiber membrane assembly 300 shown is located on the side of the container 303 such that the direction of water flow into the container 303 is perpendicular to the longitudinal direction of the plurality of hollow fiber membranes 301. When cleaning fluid is introduced through the water supply inlet 303a, the hollow fiber membranes 301 are pressed by the water flow F in a direction perpendicular to the longitudinal direction due to the cleaning fluid. As a result, the hollow fiber membranes 301 are easily damaged near the boundary between the hollow fiber membranes 301 and the molding section 305. Although it is also considered to place a baffle near the water supply inlet 303a, the effect of the baffle is limited when the flow rate of the cleaning fluid is very large.

[0059] By using a hollow fiber membrane 10 capable of achieving sufficient permeation flux and employing a component structure as described above that makes the hollow fiber membrane 10 resistant to damage, the inventors have successfully improved the cleanability of the hollow fiber membrane module 100. Specifically, according to this embodiment, the permeation flux of the hollow fiber membrane module 100 is 850 liters / m³ when a membrane pressure difference of 0.1 MPa is included. 2 Hollow fiber membrane 10 with a capacity of / h or higher. When the hollow fiber membrane module 100 is configured in a manner that satisfies these conditions, the hollow fiber membrane module 100 can be cleaned quickly.

[0060] Typically, there is a trade-off between the permeation flux and strength of hollow fiber membranes. Hollow fiber membranes with higher permeation flux tend to have lower strength. Therefore, even when attempting to shorten cleaning time by using hollow fiber membranes with higher permeation flux, high-flow-rate cleaning is difficult due to the insufficient strength of the hollow fiber membrane.

[0061] Furthermore, in the hollow fiber membrane module 100 according to this embodiment, since the flow direction of the supply water into the interior of the container 20 is parallel to the longitudinal direction of the plurality of hollow fiber membranes 10, loads in the direction perpendicular to the longitudinal direction are not easily applied to the hollow fiber membranes 10. Because loads in the direction perpendicular to the longitudinal direction are not easily applied to the hollow fiber membranes 10, even if a hollow fiber membrane 10 with a large permeation flux is used, the hollow fiber membrane 10 is not easily damaged. Thus, a hollow fiber membrane module 100 that can withstand high flow rates can be realized. Moreover, when a baffle 30 is disposed between the supply water inlet 201 and one end of the plurality of hollow fiber membranes 10, the bundle of hollow fiber membranes 10 is less likely to sway due to water flow. The hollow fiber membrane 10, which can achieve a large permeation flux, combined with a structure that can withstand high flow rates, enables a hollow fiber membrane module 100 that avoids damage to the hollow fiber membranes 10 and can be cleaned in a short time. In other words, the hollow fiber membrane module 100 can easily restore its original performance through cleaning. The time from the start of operation to obtaining the required water quality for the permeate is also relatively short.

[0062] There is no specific upper limit to the permeate flux of the hollow fiber membrane 10 at an intermembrane pressure difference of 0.1 MPa. However, if the permeate flux is too high, the barrier performance may be significantly reduced. For example, the upper limit for the permeate flux of the hollow fiber membrane 10 at an intermembrane pressure difference of 0.1 MPa is 3000 L / m³. 2 / h, or 1500 liters / m 2 / h, or 1300 liters / m 2 / h. At this time, the water supplied for operation is ultrapure water.

[0063] It can achieve a capacity of 850 L / m³ under a membrane pressure difference of 0.1 MPa. 2 Hollow fiber membranes 10 with a permeation flux of 1 h or higher can be obtained using porous material manufacturing methods including non-solvent phase separation (NIPS), thermal phase separation, polymerization phase separation, and track etching. For example, from the viewpoint of ease of production, non-solvent phase separation is desirable. To obtain hollow fiber membranes 10 with high permeation flux, for example, reducing the concentration of polymers in the polymer solution used to manufacture the hollow fiber membrane 10 can be employed. The concentration of polymers in the polymer solution is not limited, but is, for example, 22% by weight or less, and preferably 20% by weight or less. Furthermore, hollow fiber membranes 10 with high permeation flux can be manufactured by appropriately combining known methods.

[0064] In this specification, "membrane pressure difference" refers to the pressure difference between the average pressure of the supply water and the pressure of the permeate water at the permeate outlet 202. "Average pressure of the supply water" refers to the arithmetic mean of the pressure of the supply water at the supply water inlet 201 and the pressure of the concentrate water at the concentrate outlet 203. For example, by supplying ultrapure water at 25°C to the hollow fiber membrane module 100 in a manner that controls the average pressure of the supply water and the pressure at the permeate outlet 202 within the aforementioned range, the permeate flux of the hollow fiber membrane module 100 can be calculated from the permeate flow rate and the total membrane area of ​​the hollow fiber membranes 10. Furthermore, as described below, the permeate flux of the hollow fiber membrane 10 can be measured using a module having only one hollow fiber membrane 10.

[0065] During the cleaning of the hollow fiber membrane module 100, the hollow fiber membrane module 100 is, for example, cleaned at a speed of 25m. 3 Operating at a permeate flow rate of over / h. During cleaning of the hollow fiber membrane module 100, the flow rate of ultrapure water used as the cleaning fluid is, for example, 30 m³ / h. 3 The maximum permeability is 30 m³ / h. 3 / h.

[0066] Inside the container 20, a tensile load is applied to the hollow fiber membrane 10. Therefore, it is desirable for the hollow fiber membrane 10 to have sufficient tensile strength. The tensile strength of a single hollow fiber membrane 10 is, for example, 0.20 kgf or more, preferably 0.23 kgf or more, more preferably 0.25 kgf or more, and most preferably 0.29 kgf or more. If the tensile strength of the hollow fiber membrane 10 is sufficiently ensured, the hollow fiber membrane 10 is less likely to break when a large flow of supply water or cleaning fluid flows in. There is no particular upper limit to the tensile strength of the hollow fiber membrane 10, for example, 1.0 kgf.

[0067] The tensile strength (tensile breaking load) of the hollow fiber membrane 10 can be measured, for example, by the following method. A tensile test is performed using a suitable measuring device (e.g., Shimadzu AUTOGRAPH AGS-X50N) under the conditions of an effective specimen length of 100 mm, a tensile speed of 200 mm / min, and an ambient temperature of 25°C. The maximum load just before breakage is considered the tensile strength (kgf).

[0068] For example, the resistivity of the permeate water (ultrapure water) is used to determine whether cleaning has been sufficient. The more thorough the cleaning, the lower the electrolyte concentration and the higher the resistivity of the permeate water. The criteria for determining whether cleaning has been sufficient vary depending on the required water quality. For example, if the resistivity of the permeate water at 25°C is 17.5 MΩ·cm or higher, it is desirable that the resistivity of the permeate water at 25°C is 18 MΩ·cm or higher to be considered sufficient for cleaning the hollow fiber membrane module 100.

[0069] The adequacy of cleaning can also be determined based on the number of fine particles contained in a unit volume of permeate water. The criteria for determining adequacy vary depending on the required water quality. For example, it is desirable that the number of fine particles larger than 100 nm contained in 1 L of permeate water is less than 1000; even more desirable is that the number of fine particles larger than 50 nm contained in 1 L of permeate water is less than 200; and even more desirable is that the number of fine particles larger than 50 nm contained in 1 L of permeate water is less than 10. The number of fine particles in the ultrapure water can be counted based on Japanese Industrial Standard JIS K0554 (1995).

[0070] The hollow fiber membrane module 100 of this embodiment can not only be cleaned with a large permeation flux during cleaning, but also produce ultrapure water with a large permeation flux during normal operation. Therefore, according to this embodiment, it is also possible to reduce the number of hollow fiber membrane modules used for ultrapure water in a water treatment system.

[0071] Figure 5 The diagram illustrates the structure of an example of a water treatment system 400 using a hollow fiber membrane module 100. The water treatment system 400 includes a primary treatment system 410 and a secondary treatment system 420. Water treated by the primary treatment system 410 is further treated in the secondary treatment system 420. The water treatment system 400 is, for example, a system for producing ultrapure water. The produced ultrapure water is supplied to a designated point of use 430.

[0072] The primary treatment system 410 includes, sequentially upstream of the water flow direction, a UF (ultrafiltration) membrane module 401, an RO (reverse osmosis) membrane module 402, and various treatment devices 403. The various treatment devices 403 include at least one selected from, for example, a degassing device, an organic matter decomposition device (e.g., a decomposition device using ultraviolet light), an EDI (electro-deionization) device, and an ion exchange resin column. The permeate from the UF membrane module 401 is supplied to the RO membrane module 402 for treatment. The permeate from the RO membrane module 402 is supplied to the various treatment devices 403 for treatment.

[0073] The secondary treatment system 420 includes, sequentially upstream of the water flow direction, a tank 404, various treatment devices 405, and a UF membrane module 406. The various treatment devices 405 include at least one selected from, for example, a degassing device, an organic matter decomposition device (e.g., a device using ultraviolet light), an EDI (electro-deionization) device, and an ion exchange resin column. Water temporarily stored in the tank 404 is treated using the various treatment devices 405 and the UF membrane module 406. A portion of the permeate from the UF membrane module 406 is returned to the tank 404 via a circulation loop 407, ensuring continuous water circulation to the UF membrane module 406. Therefore, even if components from piping or other parts in contact with water dissolve or dust is generated, it is immediately purified by the UF membrane module 406, thus enabling a continuous supply of high-quality ultrapure water.

[0074] At least one of UF membrane modules 401 and 406 is the hollow fiber membrane module 100 of this embodiment. UF membrane module 406 is the final filtration device disposed immediately upstream of the point of use 430. A high degree of cleanliness is required for UF membrane module 406; therefore, the hollow fiber membrane module 100 of this embodiment is suitable for UF membrane module 406. Of course, the hollow fiber membrane module 100 can also be used with UF membrane module 401.

[0075] Example

[0076] To confirm the effectiveness of the present invention, the following experiments were conducted.

[0077] (Methods for measuring the permeation flux of hollow fiber membranes)

[0078] The permeation flux of the hollow fiber membrane was measured using the following method. One end of the hollow fiber membrane was injection-molded inside a polyethylene tube with an outer diameter of 10 mm and an inner diameter of 8 mm. The injection-molded portion, which was part of the polyethylene tube, was cut off to form an end face communicating with the interior of the hollow fiber membrane. The other end of the hollow fiber membrane was sealed with resin to form a resin-sealed portion. Thus, an assembly with only one hollow fiber membrane was manufactured. The length of the hollow fiber membrane, excluding the injection-molded portion and the resin-sealed portion, was 1.0 m. A load of 0.1 MPa (membrane pressure difference) was applied to the assembly using external pressure, and the permeation flux of the hollow fiber membrane was calculated by dividing the permeate volume by the membrane area calculated from the outer diameter and length of the hollow fiber membrane.

[0079] Furthermore, no flow path for concentrated water is provided in the module with only one hollow fiber membrane. Since the flow path on the permeate side is completely open (=0 Pa), the pressure of the supply water is considered as the intermembrane pressure difference.

[0080] (Manufacturing Example 1)

[0081] Polysulfone (manufactured by Solvay, UDEL (registered trademark) P-1700), N-methylpyrrolidone, and diethylene glycol were mixed in a mixer to obtain a polymer solution. The concentration of polysulfone in the polymer solution was 15.8% by weight. The concentration of diethylene glycol in the polymer solution was 25% by weight. Hollow fiber membranes were produced by continuously feeding the solution into a water tank after it was sprayed from a hollow nozzle. The properties of the obtained hollow fiber membranes are shown in Table 1.

[0082] (Manufacturing Example 2)

[0083] Hollow fiber membranes were prepared using the same method as in Manufacturing Example 1, except that the concentration of polysulfone was changed to 15.5% by weight. The properties of the resulting hollow fiber membranes are shown in Table 1.

[0084] Table 1

[0085]

[0086] (Sample 1)

[0087] Using the hollow fiber membrane obtained from Manufacturing Example 1, a reference was fabricated. Figure 1 The hollow fiber membrane module described herein has a total membrane area of ​​36.8 m². 2 .

[0088] (Sample 2)

[0089] Using the hollow fiber membrane obtained from Manufacturing Example 2, a reference was fabricated. Figure 1 The hollow fiber membrane module described herein has a total membrane area of ​​36.8 m². 2 .

[0090] [Experiment 1]

[0091] For the hollow fiber membrane module of Sample 1, the following experiment was conducted. The permeate outlet was closed, and the flow rate was 2m... 3 A flow rate of / h was used to flow ultrapure water from the supply water inlet to the concentrate outlet for one hour. Then, a leak test was conducted to investigate the presence or absence of hollow fiber membrane rupture. Then, at a flow rate of 4m... 3 / h、6m 3 / h、8m 3 / h, 10m 3 / h、12m 3 / h and 14m 3 At a flow rate of / h, ultrapure water was allowed to flow from the supply water inlet toward the concentrate outlet for one hour. A leak test was performed after each one-hour water flow. With the permeate outlet closed, the hollow fibers near the binding section were strongly stretched by the water flow toward the concentrate outlet, and the hollow fibers were sometimes damaged.

[0092] In 2-10m 3 No leaks were detected at a flow rate of / h. At a flow rate of 12m³ / h, no leaks were detected. 3 An air leak was detected in a hollow fiber membrane after ultrapure water was flowed at a flow rate of 14m / h for one hour. 3 When ultrapure water was flowed at a flow rate of [flow rate] / h for one hour, a leak was detected in another hollow fiber membrane. This result indicates that even hollow fiber membrane modules using high-strength hollow fiber membranes can experience leaks below 25m due to the continuous application of a large load perpendicular to the length of the hollow fiber membrane. 3 Hollow fiber membranes may break even at flow rates of / h. (Refer to...) Figure 4 As explained, it is difficult to achieve 25m in hollow fiber membrane modules with a structure that applies loads in the vertical direction. 3 / h of traffic.

[0093] Even the hollow fiber membrane module of Sample 1, which used a high-strength hollow fiber membrane, exhibited air leakage. Therefore, it is speculated that even more significant air leakage occurred in the hollow fiber membrane module of Sample 2, which used a low-strength hollow fiber membrane.

[0094] [Experiment 2]

[0095] The following experiment was conducted on the hollow fiber membrane module of Sample 1. The concentrate outlet was closed, and the flow rate was 5m... 3 A flow rate of / h is used to allow ultrapure water to flow from the supply water inlet towards the permeate outlet for one hour. That is, the total volume of ultrapure water permeates. Then, a leak test is performed to investigate the presence or absence of ruptures in the hollow fiber membrane. Furthermore, at a flow rate of 10m... 3 / h, 15m 3 / h, 20m 3 / h, 25m 3 / h and 30m 3 The ultrapure water was allowed to flow from the supply water inlet to the permeate outlet at a flow rate of / h for one hour. An air leakage test was performed after each one-hour water flow.

[0096] 5–30m 3 No leaks were detected at any flow rate of / h. This indicates that the hollow fiber membrane module of this embodiment is suitable for the production of ultrapure water at high flow rates and for cleaning at high flow rates. Because the supply water flows in a direction parallel to the length of the hollow fiber membrane, the hollow fiber membrane is less prone to breakage. Therefore, the hollow fiber membrane module of this embodiment can achieve a length of 25m. 3 The flow rate of / h or more and the corresponding permeation flux.

[0097] [Experiment 3]

[0098] For the hollow fiber membrane modules of Sample 1 and Sample 2, the following experiments were conducted respectively. The concentrate outlet was closed, and the flow rate was 15m... 3 / h(408 liters / m 2 A flow rate of / h causes ultrapure water to flow from the supply water inlet towards the permeate outlet. The supply water flow rate is set to 0m³ / h. 3 After / h, restore it to 15m within 2 seconds. 3 / h. Perform load-bearing tests by repeating these operations. Set one cycle to 7 seconds and perform over 10,000 load-bearing tests. Then, perform a leakage test to investigate the presence or absence of hollow fiber membrane rupture. Furthermore, at 25m... 3 / h(679 liters / m 2 The same 10,000-cycle load-bearing test was conducted at a flow rate of / h. Then, a leakage test was performed again to investigate the presence or absence of rupture in the hollow fiber membrane. The results are shown in Table 2.

[0099] Table 2

[0100]

[0101] In the hollow fiber membrane module of Sample 1, no air leakage was detected after 10,164 load tests at low flow rate or 10,658 load tests at high flow rate.

[0102] In the hollow fiber membrane module of Sample 2, no leakage was detected after 10,291 load tests at a low flow rate. However, leakage was detected during 10,000 load tests at a high flow rate for the hollow fiber membrane module of Sample 2. The reason is believed to be that the hollow fibers used in the hollow fiber membrane module of Sample 2 have slightly lower strength.

[0103] [Experiment 4-1]

[0104] (Cleaning test)

[0105] Close the concentrated water outlet of the hollow fiber membrane module in Sample 1, and spray at 12m 3A supply water flow rate of / h causes ultrapure water to flow from the supply water inlet towards the permeate outlet. The number of fine particles larger than 50 nm in the permeate is monitored in real time. The number of fine particles is detected using an Ultra DI 50 particle counter (registered trademark). The start of the cleaning cycle is set to 0 minutes, and fine particle counts are sampled at 5-minute intervals. The number of fine particles (particles / L) at a specific cleaning time (min) is calculated using the following method: Measurements are taken at 25 minutes, 20 minutes, 15 minutes, 10 minutes, 5 minutes, or 0 minutes from the specific cleaning time, and the arithmetic mean of these six data points is taken as the measurement value for the specific cleaning time. The results are expressed as follows: Figure 6 middle.

[0106] [Experiment 4-2]

[0107] For the hollow fiber membrane module of sample 1, in addition to using 9m 3 The same experiment as Experiment 4-1 was conducted with a supply water flow rate of / h to allow ultrapure water to flow. The results are expressed as follows: Figure 6 middle.

[0108] Figure 6 The vertical axis represents the number of fine particles larger than 50 nm detected (particles / L). The horizontal axis represents the operating time (water flow time). The number of fine particles detected in the permeate water of the hollow fiber membrane module in Experiment 4-1 converged earlier than the number detected in the permeate water of the hollow fiber membrane module in Experiment 4-2. For 12m 3 At a flow rate of / h (Experiment 4-1), the number of fine particles was less than 10 particles / L during a 75-minute operation. For a 9m... 3 At a flow rate of / h, the number of fine particles is less than 10 particles / L when the operating time exceeds 135 minutes. This indicates that the hollow fiber membrane module can be cleaned in a shorter time during high-flow-rate operation, i.e., it starts up quickly.

[0109] Figure 6 The result indicates 12m 3 The results of cleaning the hollow fiber membrane module of Sample 1 at a flow rate of / h. However, as demonstrated in Experiment 2, the hollow fiber membrane module of Sample 1 can also withstand 25m 3 / h and 30m 3 Cleaning at various flow rates per hour. It is predicted that if the flow rate is increased, the time taken to reach a minimum of 10 particles / L for cleaning will be further reduced.

[0110] Industrial availability

[0111] The hollow fiber membrane module of the present invention is useful for water treatment systems used to produce ultrapure water.

Claims

1. A hollow fiber membrane module, which is an externally pressurized hollow fiber membrane module, wherein, The hollow fiber membrane module includes: Multiple hollow fiber membranes; A container that houses the plurality of hollow fiber membranes; A water supply inlet is provided at one end of the container such that the direction of water flow into the interior of the container is parallel to the longitudinal direction of the plurality of hollow fiber membranes; The first binding portion is located at one end of the plurality of hollow fiber membranes; The second binding portion is located at the other end of the plurality of hollow fiber membranes; and A baffle plate is disposed between the water supply inlet and one end of the plurality of hollow fiber membranes. In the radial direction of the partition, the first binding portion is located inside the outer edge of the partition. The partition plate has a plurality of through holes on its outer periphery, which overlap with the outer edge of the first binding part or are located outside the outer edge of the first binding part. One end of each of the plurality of hollow fiber membranes is sealed using the first binding portion. The other end of the plurality of hollow fiber membranes opens at the end face of the second binding portion. The second restraint part separates the supply water flow path from the permeation water flow path inside the container. The permeation flux of the hollow fiber membrane at a membrane pressure difference of 0.1 MPa is 850 L / m³. 2 / h or more.

2. The hollow fiber membrane module according to claim 1, wherein, The hollow fiber membrane has a tensile strength of 0.20 kgf or higher.

3. The hollow fiber membrane module according to claim 1, wherein, The hollow fiber membrane module also includes: Multiple inner mesh layers, which bind the multiple hollow fiber membranes in a manner that divides the multiple hollow fiber membranes into multiple bundles; and The outer mesh binds together the plurality of inner meshes.

4. The hollow fiber membrane module according to claim 1, wherein, The hollow fiber membrane module also includes a concentrated water outlet, which is located at the other end of the container such that the direction of the supply water flowing out from the inside of the container to the outside is perpendicular to the length direction.

5. The hollow fiber membrane module according to claim 1, wherein, This hollow fiber membrane module is used in the production of ultrapure water.

6. The hollow fiber membrane module according to claim 1, wherein, The container includes a container body, a first cap installed at one end of the container body, and a second cap installed at the other end of the container. Inside the container are internal spaces SP1, SP2, and SP3, which function as flow paths. Internal space SP1 is the internal space of the container body and functions as the water supply path. Internal space SP2 is the internal space of the first cover and functions as the water supply path. Internal space SP3 is the internal space of the second cover and functions as the permeation path. The supplied water flows from the internal space SP2 toward the internal space SP1 through the plurality of through holes in the partition. Permeate water is delivered from the plurality of hollow fiber membranes to the outside of the hollow fiber membrane assembly via the internal space SP3.

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