JP2010234198A - Hollow fiber membrane module, and filtration method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact hollow fiber membrane module capable of stably preparing water of good quality, and a filtration method using the same. <P>SOLUTION: The hollow fiber membrane module includes a fiber bundle constituted of a plurality of hollow fiber membranes, a cylindrical case that houses the fiber bundle and has a pair of nozzles disposed on its side face, a pair of fixed parts each disposed on either end part of the fiber bundle in the cylindrical case and formed of a casting agent for sealing the gaps between the outer circumferential faces of the hollow fiber membranes and between the outer circumferential faces thereof and the inner face of the cylindrical case, and a pair of distribution cylinders each sealed by the corresponding fixed part at one end thereof and each extending in a manner of surrounding either end part of the fiber bundle respectively, with each of the pair of distribution cylinders having an opening disposed on a position distanced from the corresponding fixed part to allow water present inside the distribution cylinders to flow therethrough to the nozzles, and with at least one of the pair of distribution cylinders having a plurality of small holes of an equivalent diameter of at least 1 mm and not larger than 10 mm each disposed on the interfacial position of the corresponding fixed part to penetrate the distribution cylinder from the outer face through the inner face thereof. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a filtration module and a filtration method for performing turbidity and sterilization on relatively clear raw water or ultrapure water such as river water and groundwater. The present invention particularly relates to a hollow fiber membrane module suitable as a security filter in an ultrapure water production line and a filtration method using the same.

  In lines that produce ultrapure water used in the manufacture of electronic and electrical parts such as semiconductors and display elements, supply ultrapure water produced using microfiltration membranes, ion exchange resins, and reverse osmosis filtration membranes to use points Immediately before the filtration, it is filtered using a microfiltration membrane or an ultrafiltration membrane. This microfiltration membrane or ultrafiltration membrane functions as a security filter. As the filtration membrane module for this application, an external pressure filtration membrane module that supplies raw water to the outside of the hollow fiber membrane and performs filtration has been mainly used (see Non-Patent Documents 1 and 2).

  On the other hand, in recent years, the amount of ultrapure water to be used has been increased along with the expansion of the production scale, and the ultrapure water production equipment has also been increasing in size, and there is an increasing demand for making the production equipment compact. Under such circumstances, a module having a high filtration capacity, that is, a module having a high filtration flow rate per module and a high filtration flow rate per unit volume is demanded.

  In a conventional external pressure module, when the amount of water supplied is increased and the throughput per unit time is increased, water flows at high speed in the module, which causes the hollow fiber membrane to vibrate vigorously. Happens. This is because the hollow fiber membranes and the hollow fiber membranes rub against the component members in the module while the filtration is continued for a long period of time, so that the pores on the membrane surface are clogged and the water permeability is lowered. It will break and cause the quality of filtered water to deteriorate.

  As a method for preventing damage to the hollow fiber membrane due to such water flow, a method of providing a protective cylinder between the housing and the hollow fiber membrane bundle has been proposed (see Patent Documents 1-3).

JP-A-62-204804 Japanese Patent Publication No. 07-102307 JP 2000-37616 A

Kuroda, “Development of Ultra Pure Water Piping System Final Filter for Ultra Pure Water”, Piping and Equipment, Sanko Planning Publishing Department, March 1997, Vol. 37, No. 3, p. 2-7 Ito, “Membrane separation technology in ultrapure water production process”, Clean Technology, Nippon Kogyo Publishing, October 1998, Vol. 8, No. 10, p. 22-25

  However, even if the protective cylinder as described above is used, if the filtration is continuously performed at a high flow rate, there is a problem that the quality of the filtered water is deteriorated due to the breakage of the hollow fiber membrane or the like. Therefore, an object of the present invention is to provide a hollow fiber membrane module that is compact and can stably obtain water of good water quality, and a filtration method using the same.

  As a result of intensive studies to solve the above problems, the present inventor is extremely useful in solving the above problems by providing a rectifying cylinder having a specific structure in a cylindrical case that accommodates a hollow fiber membrane. As a result, the present invention has been made.

  That is, the present invention provides a yarn bundle composed of a number of hollow fiber membranes, a cylindrical case containing the yarn bundle and having nozzles on the side surfaces, and hollow fiber membranes at both ends of the yarn bundle in the cylindrical case. A pair of fixing portions made of a casting agent that seals the outer surfaces and the gap between the outer surface and the inner surface of the cylindrical case, and one end is sealed by the fixing portion and extends so as to surround both ends of the yarn bundle. A pair of rectifying cylinders, and the pair of rectifying cylinders each have an opening through which water inside the rectifying cylinder can flow to the nozzle at a position spaced apart from the fixing part. Provided is a hollow fiber membrane module having a small hole with an equivalent diameter of 1 mm or more and 10 mm or less penetrating from the outer surface to the inner surface of the flow straightening tube at the interface position.

  According to the hollow fiber membrane module of the present invention, vibration of the hollow fiber membrane during water flow can be sufficiently suppressed by using a rectifying cylinder having an opening and a small hole at a predetermined position. In addition, the shearing force that the hollow fiber membrane receives from the water flow in the vicinity of the fixed portion can be sufficiently reduced. Therefore, the damage of the hollow fiber membrane due to the water flow can be sufficiently suppressed, and a high filtration capacity can be achieved as compared with the conventional filtration device.

  Further, according to the hollow fiber membrane module of the present invention, air that tends to remain on the upper end side of the yarn bundle of the hollow fiber membrane is moved to the outside of the rectifying cylinder through a small hole provided at the interface position of the fixing portion, and further, the module Can be discharged to the outside. By sufficiently reducing the air remaining in the module, it is possible to sufficiently suppress the growth of microorganisms in the module and to continuously produce filtered water with excellent water quality over a long period of time.

  The small hole is preferably provided in a portion where the distance between the inner surface of the flow straightening cylinder and the hollow fiber membrane forming the outermost surface of the yarn bundle is 5 mm or more. By adopting such a configuration, it is possible to further reduce the remaining bubbles in the flow straightening cylinder. Further, the small hole is not necessarily a through-hole formed independently in the rectifying cylinder, and may be a part of the slit provided at the end of the rectifying cylinder. That is, the flow straightening cylinder having a small hole has a slit having a width of 1 mm or more and 10 mm or less extending in the longitudinal direction from one end, and the small hole is formed by embedding a part of the slit by a fixing portion. May be.

  In the present invention, a plurality of small bundles formed by bundling a plurality of hollow fiber membranes in a bundle are filled in a cylindrical case in parallel, and at least at the interface position of the fixed part, compared with other parts And it is preferable to have a part with a low packing density of a hollow fiber membrane. By providing a portion having a low filling density of the hollow fiber membrane in the cylindrical case, it is possible to reduce the resistance of water flowing in the cylindrical case. In addition, there is an advantage that the bubbles easily move to the small holes through the portion where the packing density of the hollow fiber membrane is low.

  Furthermore, the present invention provides a filtration method using the hollow fiber membrane module. That is, the filtration method according to the present invention includes a step of installing the hollow fiber membrane module so that a small hole provided in the rectifying cylinder is disposed above, and the water to be treated from the lower side of the module. And a step of collecting filtered water flowing out of the hollow fiber membrane from the nozzle of the cylindrical case.

  According to the filtration method of the present invention, by using the hollow fiber membrane module, it is possible to sufficiently reduce the damage of the hollow fiber membrane due to water flow, and to sufficiently suppress the growth of microorganisms in the module, and to have excellent water quality. Filtered water can be produced stably over a long period of time.

  According to the present invention, a hollow fiber membrane module having a high filtration capacity while being relatively compact is provided. According to the filtration method using this hollow fiber membrane module, excellent water quality filtered water can be stably produced over a long period of time.

It is sectional drawing which shows typically one Embodiment of the hollow fiber membrane module which concerns on this invention. It is the II-II sectional view taken on the line of the hollow fiber membrane module shown in FIG. It is the III-III sectional view taken on the line of the rectification | straightening cylinder shown in FIG. It is the schematic which shows an example of a structure of the filtration apparatus provided with the hollow fiber membrane module of this invention. It is the schematic which shows the other example of a structure of the filtration apparatus provided with the hollow fiber membrane module of this invention. It is a fragmentary sectional view showing typically other embodiments of the hollow fiber membrane module concerning the present invention. It is a fragmentary sectional view showing typically other embodiment of the hollow fiber membrane module concerning the present invention. It is sectional drawing which shows typically other embodiment of the hollow fiber membrane module which concerns on this invention. It is sectional drawing which shows the structure of the hollow fiber membrane module which concerns on the reference example 4 typically. It is XX sectional drawing of the hollow fiber membrane module shown in FIG. It is the XI-XI sectional view taken on the line of the cylindrical member shown in FIG.

<Hollow fiber membrane module>
An embodiment of a hollow fiber membrane module according to the present invention will be described with reference to FIGS. A hollow fiber membrane module 10 according to this embodiment includes a yarn bundle 1 made up of a number of hollow fiber membranes 1a, a cylindrical case 2 that accommodates the yarn bundle 1, and a casting provided at both ends of the yarn bundle 1. A pair of fixing portions 3a and 3b made of an agent and a pair of rectifying cylinders 4 and 5 disposed so as to surround both ends of the yarn bundle 1 are provided. The module 10 is configured so that pipe connection caps 6a and 6b can be attached to both ends of the cylindrical case 2 by nuts 7a and 7b, respectively. By tightening the nuts 7a and 7b, the portions are sealed by the O-rings 8a and 8b arranged in the grooves of the caps 6a and 6b.

  The yarn bundle 1 is formed by a large number of hollow fiber membranes 1a. Although many hollow fiber membranes 1a can be bundled together to form a yarn bundle (see FIG. 8), as shown in FIG. 2, the yarn bundle 1 is divided into a plurality of small bundles 1b. It is preferable. In particular, it is more preferable that a small bundle 1b composed of a large number of hollow fiber membranes 1a is wrapped with a net 1c. Thus, by providing the module 10 with a portion that is not filled with the hollow fiber membrane (portion with a low membrane filling density), the resistance of the water flowing outside the hollow fiber membrane 1a is reduced, and as a result, higher module water permeability. Performance can be realized. In addition, as long as it can cover the surface of the small bundle 1b and consists of a raw material which has water permeability, a nonwoven fabric etc. may be used instead of a net | network as what wraps a small bundle.

  The type of the hollow fiber membrane 1a can be appropriately selected according to the use of the module 10. Specific examples of the hollow fiber membrane 1a include an ultrafiltration membrane and a microfiltration membrane. For example, if the module 10 is used for a final filter for ultrapure water, the hollow fiber membrane 1a is preferably an ultrafiltration membrane having an average pore diameter of 0.05 μm or less (more preferably 0.02 μm or less). The material of the hollow fiber membrane 1a may be appropriately selected depending on the application, and can be selected from, for example, polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl alcohol, cellulose acetate, and polyacrylonitrile.

The hollow fiber membrane 1a has an inner area-converted short thread water permeability (25 ° C.) of 2000 L / m ² /hr/0.1 MPa (hereinafter, the unit of short thread water permeability is referred to as “LMH”) or more. Is preferably 4000 LMH or more. The inner diameter of the hollow fiber membrane 1a is preferably 0.7 to 1.0 mm, particularly preferably 0.70 mm to 0.85 mm. As will be described later, the module 10 of the present embodiment can sufficiently suppress the influence due to vibration during water flow, and therefore, by using the hollow fiber membrane having the short thread water permeability and the inner diameter, it is about twice as much as the conventional one. Module water permeability can be realized.

  The cylindrical case 2 is made of a cylindrical member having openings at both ends, and has nozzles 2a and 2b provided in the vicinity of the interfaces Fa and Fb of the fixing portions 3a and 3b. The interface of the fixed part here means a surface on one side of the fixed part where the base end of the rectifying tube is embedded. The material of the cylindrical case 2 can be appropriately selected from metals and plastics according to the application. From the viewpoint of ease of processing and weight reduction, the cylindrical case 2 is preferably formed of plastics. Specific examples of plastics include polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, ABS resin, and A vinyl chloride resin etc. are mentioned. Note that the number of nozzles provided in the vicinity of the interfaces Fa and Fb is not necessarily one, and a plurality of nozzles can also be provided in the part.

  The cylindrical case 2 has an outer diameter of 140 to 200 mm, a length of preferably 700 to 1400 mm, an outer diameter of 160 to 180 mm, and a length of 800 to 1100 mm. It is particularly preferred. When the cylindrical case 2 having a size in this range is used, a high module water permeability and the highest module water permeability can be realized. In addition to this, since it is possible to have the module 10 by one person with this size, there is an advantage that handling property is remarkably good. The “outer diameter” of the cylindrical case 2 herein means the outer diameter of the cylinder in the filtration region at the center of the module. The “length” of the cylindrical case 2 means the distance between both end faces of the hollow fiber membrane 1a.

  The fixing portions 3 a and 3 b are made of a casting agent that seals the outer surfaces of the hollow fiber membrane 1 a and the gap between the outer surface and the inner surface of the cylindrical case 2 at both ends of the yarn bundle 1 in the cylindrical case 2. Is. A thermosetting resin such as an epoxy resin or a urethane resin is suitable as the casting agent that forms the fixing portions 3a and 3b. By fixing and sealing both ends of the yarn bundle 1 with the fixing portions 3a and 3b, the hollow portions of the hollow fiber membrane 1a are opened at both end surfaces of the yarn bundle 1. The fixing portions 3a and 3b also serve to seal the openings of the base end portions 4a and 5a of the rectifying cylinders 4 and 5.

  The rectifying cylinders 4 and 5 extend from the positions of the interfaces Fa and Fb of the fixing portions 3a and 3b toward the center of the module 10, respectively, and surround the yarn bundle 1 near the fixing portions 3a and 3b. Yes. The material of the rectifying cylinders 4 and 5 may be appropriately selected according to the application, and examples thereof include polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, ABS resin, and vinyl chloride resin.

  As described above, the pair of rectifying cylinders 4 and 5 have the base end portions 4a and 5a sealed with the fixing portions 3a and 3b, respectively. That is, the base end part 4a of the rectifying cylinder 4 is embedded in the fixed part 3a, and the base end part 5a of the rectifying cylinder 5 is embedded in the fixed part 3b. The arrangement method of the rectifying cylinders 4 and 5 is generally a method in which the base end portions 4a and 5a are embedded and fixed in the fixing portions 3a and 3b, respectively. However, the module 10 is manufactured through a process in which the rectifying cylinders 4 and 5 are fixed in advance to the cylindrical case 2 and then the base ends 4a and 5a of the rectifying cylinders 4 and 5 are embedded in the fixing parts 3a and 3b. Also good.

  The rectifying cylinders 4 and 5 are opened without sealing the openings of the end portions 4b and 5b. These openings are located at positions separated from the interfaces Fa and Fb of the fixing portions 3a and 3b, respectively, and play a role of circulating water inside the rectifying cylinders 4 and 5 to the nozzles 2a and 2b. That is, the water in the rectifying cylinder 4 flows out from the opening of the tip 4b into the space between the yarn bundle 1 and the cylindrical case 2 and passes through the gap between the inner surface of the cylindrical case 2 and the outer surface of the rectifying cylinder 4. It is discharged from the nozzle 2a. Similarly, the water in the rectifying cylinder 5 flows out from the opening of the tip 5 b into the space between the yarn bundle 1 and the cylindrical case 2, and the gap between the inner surface of the cylindrical case 2 and the outer surface of the rectifying cylinder 5. Through the nozzle 2b.

この条件を満たすように開口面積Ｓ_１を設定することにより、この部分を水が流通する際の圧損を小さくでき、高いモジュール透水量を実現できる。なお、ここでいう「モジュール透水量」とは、膜間差圧０．１ＭＰａを印加したときの２５℃における１時間当たりのろ過量（ｍ^３／ｈｒ／０．１ＭＰａ＠２５℃）をいう。また、「モジュール透水性能」とは、上記モジュール透水量をモジュールの見かけ容積で除した値（（ｍ^３／ｈｒ／０．１ＭＰａ）／ｍ^３＠２５℃）をいう。なお、開口面積Ｓ_１は、下記式（２）によって算出される値である。

式中、Ｄ_１は整流筒の先端部の内径（ｍ）を示し、ｄ_Ｏは中空糸膜の外径（ｍ）を示し、Ｎは糸束を成す中空糸膜の本数を示す。 When the opening area at the tip of the flow straightening cylinder is S ₁ (m ² ) and the maximum filtration flow rate of the hollow fiber membrane module is Q (m ³ / s), the opening area S ₁ is expressed by the following inequality (1). It is preferable to satisfy the following conditions.

By setting the opening area S ₁ so as to satisfy this condition, this part can be reduced pressure loss when water flows, can achieve high module water permeability. The “module water permeability” here refers to the filtration rate per hour (m ³ /hr/0.1 MPa @ 25 ° C.) at 25 ° C. when a transmembrane pressure difference of 0.1 MPa is applied. The “module water permeability” refers to a value obtained by dividing the module water permeability by the apparent volume of the module ((m ³ /hr/0.1 MPa) / m ³ @ 25 ° C.). Incidentally, the opening area S ₁ is the value calculated by the following equation (2).

In the formula, D ₁ represents the inner diameter (m) of the tip of the rectifying cylinder, d _O represents the outer diameter (m) of the hollow fiber membrane, and N represents the number of hollow fiber membranes forming the yarn bundle.

  The openings of the tip portions 4b and 5b of the rectifying cylinders 4 and 5 are preferably at least 30 mm away from the interfaces Fa and Fb of the fixed portion, respectively, and more preferably 50 mm or more. That is, it is preferable to install the rectifying cylinders 4 and 5 so as to protrude from the respective interfaces Fa and Fb of the fixing portions 3a and 3b with the above length. By surrounding the both ends of the yarn bundle 1 with the straightening tubes 4 and 5 having such a length, the hollow fiber membrane 1a can be effectively prevented from being damaged in the vicinity of the interfaces Fa and Fb. This is because the flow of water in the direction crossing the hollow fiber membrane 1a occurs at a position away from the interfaces Fa and Fb of the fixing portions 3a and 3b, so that the shearing force applied to the hollow fiber membrane 1a is extremely near the interfaces Fa and Fb. This is thought to be due to mitigation.

  One rectifying cylinder 4 of the pair of rectifying cylinders 4 and 5 has a plurality of small holes 4c having a predetermined size at the interface position of the fixed portion 3a. The small hole 4c penetrates from the outer surface to the inner surface of the rectifying cylinder 4 so that air and water can circulate. Here, a case where a small hole 4c is formed in one of the rectifying cylinders 4 and a small hole is not formed in the other rectifying cylinder 5 will be described. A small hole having the same size may be provided.

  The small hole 4 c has a function of causing the air outside the hollow fiber membrane 1 a inside the module 10 to flow out of the module 10. When internal pressure filtration is performed, air bubbles are likely to accumulate on the outer peripheral portion of the yarn bundle 1, and air may not be sufficiently replaced with water even during water flow. As in this embodiment, by providing a small hole 4c in the rectifying cylinder 4, bubbles flow along with the water to the outside of the rectifying cylinder 4 through the small hole 4c and further toward the nozzle 2a, and the bubbles are discharged from the nozzle 2a to the outside of the module 10. And can be discharged.

  If the flow straightening cylinder in which the small holes 4c are not formed is used and the filtration is continued in a state where air bubbles are accumulated on the outer periphery of the yarn bundle, the microorganisms present in the air bubbles may grow. In internal pressure type filtration in which water to be treated is introduced into the hollow portion of the hollow fiber membrane to obtain filtered water outside the hollow fiber membrane, microorganisms are mixed in the filtered water, leading to deterioration of water quality. Therefore, when performing internal pressure filtration, it is an important point in continuous production of filtered water with good water quality to sufficiently exclude air outside the hollow fiber membrane, particularly outside the yarn bundle. .

式中、Ｓ_２は小穴の開口面積（ｍ^２）を示し、Ｌは小穴の縁の全長（ｍ）を示す。なお、整流筒の内面と外面との間で小穴の寸法が変化している場合には、最も小さい値をＬとする。 The equivalent diameter of the small holes 4c is 1 mm or more and 10 mm or less, and particularly preferably 2 mm or more and 9 mm or less. The equivalent diameter R of the small hole is a value calculated by the following formula (3).

In the formula, S ₂ represents the opening area (m ² ) of the small hole, and L represents the total length (m) of the edge of the small hole. In addition, when the dimension of the small hole is changing between the inner surface and the outer surface of the flow straightening cylinder, the smallest value is set to L.

開口面積比（Ｓ_３／Ｓ_１）を上記範囲内に設定することによって、通水時において小穴４ｃから流出する水量を適度な量とすることができる。Ｓ_３／Ｓ_１を０．００５以上とすることによって、０．００５未満の場合と比較して小穴４ｃから空気を十分に流出させることができる。他方、Ｓ_３／Ｓ_１を０．１以下とすることによって、０．１を超える場合と比較して固定部３ａの界面Ｆａ付近における中空糸膜１ａへの水流による剪断力が軽減され、中空糸膜１ａのダメージを十分に抑制できる。Ｓ_３／Ｓ_１は、０．０１以上０．０５以下であるのが特に好ましい。なお、小穴４ｃの形状は円形や楕円形に限定されるものではなく、三角形、四角形等の多角形であってもよい。 The number of small holes 4c for forming the flow-guide cylinder 4 is not particularly limited, it is preferable that the total opening area S ₃ of a plurality of small holes 4c is set so as to satisfy the condition represented by the following inequality (4).

By setting the opening area ratio (S ₃ / S ₁ ) within the above range, the amount of water flowing out from the small hole 4c during water flow can be set to an appropriate amount. By setting S ₃ / S ₁ to be 0.005 or more, it is possible to sufficiently allow air to flow out from the small hole 4c as compared with the case of less than 0.005. On the other hand, by setting S ₃ / S ₁ to be 0.1 or less, the shearing force due to the water flow to the hollow fiber membrane 1a in the vicinity of the interface Fa of the fixing portion 3a is reduced as compared to the case where S ₃ / S ₁ exceeds 0.1. The damage to the yarn film 1a can be sufficiently suppressed. S ₃ / S ₁ is particularly preferably 0.01 or more and 0.05 or less. The shape of the small hole 4c is not limited to a circle or an ellipse, and may be a polygon such as a triangle or a rectangle.

  As shown in FIGS. 1 and 3, the small hole 4 c can be provided as an independent through hole in advance on the side surface of the rectifying cylinder 4. When the fixing portion 3a is formed by the centrifugal casting method, the interface Fa forms a curved surface based on the rotation direction, and therefore it is preferable to set the position of the small hole according to the curved surface.

  As shown in FIG. 2, the small hole 4c is provided at a position where the distance between the inner surface of the rectifying tube 4 and the hollow fiber membrane 1a forming the outermost surface of the yarn bundle 1 is 5 mm or more. Preferably it is. In other words, it is preferable to fix the yarn bundle 1 and the rectifying cylinder 4 in the cylindrical case 2 so that the portion of the rectifying cylinder 4 in which the small hole 4c is formed and the outermost surface of the yarn bundle 1 are separated by 5 mm or more.

  By providing a certain space between the small hole 4c and the yarn bundle 1 as described above, the following effects are exhibited. That is, air bubbles in the rectifying cylinder 4 can easily reach the small hole 4c through this space, and the remaining of air in the rectifying cylinder 4 can be prevented more reliably. In addition to this, as compared with the case where such a space is not provided, the flow area of water in the vicinity of the small hole 4c is increased, and the flow velocity in the region can be reduced. Thereby, it is considered that the force acting on the hollow fiber membrane 1a in the vicinity of the small hole 4c is reduced, and the breakage of the hollow fiber membrane 1a can be further suppressed. Such an effect has been confirmed by Examples and Reference Examples described later.

  In the module 10 according to the present embodiment, the yarn bundle 1 is formed by the four small bundles 1b, so that a region not filled with the hollow fiber membrane 1a is formed in the module 10 as described above. That is, as shown in FIG. 2, the hollow fiber membrane 1a is not filled in the concave portion 1e on the outermost surface of the yarn bundle 1 formed by the central portion 1d of the yarn bundle 1 and the two adjacent small bundles 1b. In the present embodiment, by fixing the yarn bundle 1 in the rectifying cylinder 4 so that the positions of the concave portion 1e and the small hole 4c coincide, the distance between the small hole 4c and the outermost surface of the yarn bundle 1 becomes 5 mm or more. Yes.

  In addition, as shown in FIGS. 9-11, the cylinder 40 for protection which has many holes 40a is known as what protects the edge part of the yarn bundle 1. FIG. The protective cylinder 40 is intended to restrain the outer periphery of the yarn bundle 1, thereby preventing excessive vibration of the hollow fiber membrane 1a and suppressing breakage of the hollow fiber membrane 1a. However, when filtration is performed over a long period of time using a hollow fiber membrane module equipped with the protective cylinder 40, the hollow fiber membrane 1a continuously receives a unidirectional force from the water flow, thereby creeping the hollow fiber membrane 1a. Destruction is considered to occur. That is, it is difficult to prevent creep-like breakage by a method of simply restraining the outer periphery of the yarn bundle 1, and it is considered that damage due to water flow cannot be sufficiently reduced.

<Filtration method>
A method for filtering the water to be treated (raw water) using the hollow fiber membrane module 10 will be described with reference to FIG. The filtration apparatus 100 shown in FIG. 4 is for performing the internal pressure type filtration which supplies to-be-processed water to the hollow part of the hollow fiber membrane 1a, and filters outside. The filtration device 100 includes a module 10, a pipe L1 for supplying water to be treated, a pipe L2 and a pipe L3 for discharging filtered water and circulating water from the module 10, respectively, and a pressure disposed in the middle of these pipes. It consists of a meter and a valve.

  First, the module 10 is vertically arranged so that the rectifying cylinder 4 having the small hole 4c is on the top. The treated water supply pipe L1 is connected to the pipe connection cap 6b, and the circulating water discharge pipe L3 is connected to the pipe connection cap 6a. Further, the filtrate drain pipes L2a and L2b are connected to the upper nozzle 2a and the lower nozzle 2b of the cylindrical case 2, respectively.

  The treated water is supplied to the hollow portion of the hollow fiber membrane 1a by introducing the treated water into the module 10 through the treated water supply pipe L1. The filtered water flowing out from the outer surface side of the hollow fiber membrane 1a is collected from both the upper nozzle 2a and the lower nozzle 2b. By performing such internal pressure filtration with the module 10, it is possible to stably obtain filtered water with good water quality for a long period of time without causing damage to the hollow fiber membrane 1a.

  It is preferable to perform the filtration operation while allowing about 2 to 5% of the supplied water amount to flow out as circulating water from the hollow portion of the upper hollow fiber membrane 1a. In this way, fine particles or the like excluded by the hollow fiber membrane 1a are discharged out of the module 10, so that the membrane surface is less likely to be clogged, and a stable amount of filtered water can be obtained over a longer period of time.

  As shown in FIG. 4, the filtrate discharge pipe L2b connected to the lower nozzle 2b rises with an elbow and merges with the other filtrate discharge pipe L2a. When both the upper and lower flow straightening tubes have the same structure, the upper and lower filtered water discharge pipes L2a and L2b are merged near the nozzle on the side opposite to the side to which the water to be treated is supplied, and the water to be treated is supplied. It is preferable to lead out to the side opposite to the side. As a result, the flow resistance in the filtered water module 10 and the flow resistance in the filtrate discharge pipe L2 are balanced, and as a result, the amount of filtrate from the upper nozzle and the amount of filtrate from the lower nozzle are almost the same. Become. Accordingly, there is no need to provide a flow rate adjusting valve in the filtrate discharge pipe L2 in order to balance the amount of filtrate flowing out from the nozzles 2a and 2b, and as a result, there is an advantage that the number of valves can be reduced.

  The module 10 can be used not only for internal pressure filtration but also for external pressure filtration depending on applications. The filtration apparatus 200 shown in FIG. 5 is for supplying to-be-processed water to the outer side of the hollow fiber membrane 1a, and filtering to the hollow part side. For example, in a final filter application of ultrapure water, a method of supplying treated water from the lower side and deriving filtered water to the upper side so that air does not accumulate in the piping is preferable.

  The filtration device 200 includes a hollow fiber membrane module 10, a pipe L5 for supplying water to be treated thereto, pipes L6a, L6b and a pipe L7 for discharging filtered water and circulating water from the module 10, respectively, and in the middle of these pipes. It consists of a pressure gauge, a valve and the like. In addition, before starting the process by the filtration apparatus 200, the process of introduce | transducing water into the module 10 through the filtered water discharge pipe L6b, for example, and supplying it to the hollow part of the hollow fiber membrane 1a can also be implemented. By performing this process, the air in the module 10 can be sufficiently discharged through the small holes 4c and the nozzles 2a. After exhausting the air in the module 10 sufficiently, it is preferable to start external pressure filtration by switching a valve or the like.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the case where the small hole 4c is a through hole formed independently on the side surface of the rectifying cylinder 4 is illustrated, but as shown in FIG. A plurality of slits 4d may be provided at the end, and small holes may be formed using the slits 4d. By embedding the base end portion 4a of the rectifying cylinder 4 in the fixed portion 3a, a small hole is formed at the interface position of the fixed portion 3a.

  When a small hole is provided using a slit, there is an advantage that a small hole can be formed relatively easily at the interface position of the fixed portion 3a without strictly controlling the position of the hole to be formed in advance or the position of the fixed portion interface. . The width of each slit 4d is preferably 1 to 10 mm from the viewpoint of sufficiently removing air in the module 10 and sufficiently suppressing damage to the hollow fiber membrane 1a due to water flow during water flow. It is particularly preferred that In FIG. 6, the illustration of the yarn bundle 1 and the like is omitted.

  Moreover, in the said embodiment, although the case where the opening of the front-end | tip part 4b of the rectifying cylinder 4 functions as an opening which distribute | circulates the water inside the rectifying cylinder 4 to the nozzle 2a was illustrated, the structure of the said opening is limited to this. Is not to be done. The opening may be provided on the side surface of the rectifying cylinder as shown in FIG. 7, for example, as long as the opening is at a certain distance from the interface Fa of the fixed portion 3 a.

  In the hollow fiber membrane module 20 shown in FIG. 7, the rectifying cylinder 14 is formed of a cylindrical member whose diameter increases from the base end portion 14 a toward the tip end portion 14 b, and the tip end portion 14 b is joined to the inner surface of the cylindrical case 2. . An opening 14 c is formed on the side surface of the rectifying cylinder 14, and water in the rectifying cylinder 14 flows out from the opening 14 c to the outside of the rectifying cylinder 14 and passes through a gap between the outer surface of the rectifying cylinder 14 and the inner surface of the cylindrical case 2. Thus, it can flow out to the nozzle 2a. From the viewpoint of effectively suppressing damage to the hollow fiber membrane 1a due to the water flow, the position of the opening 14c is preferably at least 30 mm away from the interface Fa of the fixed portion, and more preferably 50 mm or more away. In FIG. 7, the illustration of the yarn bundle 1 and the like is omitted.

式中、Ｗ_１及びＷ_２は開口の上辺及び下辺の長さ（ｍ）をそれぞれ示し、ｈは開口の高さ（ｍ）を示し、ｎは開口の数を示す。 The number and shape of the openings 14c formed on the side surface of the rectifying cylinder 14 are not particularly limited. However, it is preferable that the opening area S ₁ satisfies the condition expressed by the inequality (1). In this case, the opening area S ₁ is the value calculated by the following equation (5).

In the formula, W ₁ and W ₂ indicate the lengths (m) of the upper and lower sides of the opening, h indicates the height (m) of the opening, and n indicates the number of openings.

In the following examples and reference examples, a polysulfone ultrafiltration membrane was used as the hollow fiber membrane. The characteristics are shown below.
Inner diameter / outer diameter: 0.75 mm / 1.35 mm,
Internal surface area converted short thread water permeability: 4200 LMH (measured value at membrane effective length of 5 cm),
Tensile strength: 5.4 MPa,
Tensile elongation at break: 100%.

  The amount of water permeated through the hollow fiber membrane is the amount of filtered water (LMH) when ultrafiltrated water at 25 ° C. is permeated from the inner surface to the outer surface of the hollow fiber membrane having a length of 50 mm. In calculating the water permeability, the effective membrane area was converted on the inner surface. The breaking strength and breaking elongation of the hollow fiber membrane were measured using an autograph AGS-5D manufactured by Shimadzu Corporation at a sample length of 30 mm and a pulling speed of 50 mm / min. The breaking strength (MPa) is a value calculated by dividing the breaking load per hollow fiber membrane by the cross-sectional area of the membrane before pulling. The elongation at break (%) is the ratio of the length stretched to break to the original length.

[Example 1]
<Production of hollow fiber membrane module>

As the cylindrical case, a transparent polysulfone having the same configuration as the cylindrical case 2 shown in FIG. 1 was used. The dimensions of this cylindrical case are as follows.
Cylindrical inner diameter / outer diameter in the filtration region: 154 mm / 170 mm,
Inner diameter / outer diameter of cylindrical part in nozzle part: 162 mm / 183 mm,
Nozzle inner diameter: 58 mm,
Length of cylindrical case / distance between nozzle centers: 1050 mm / 872 mm.

  Two transparent polysulfone cylinders (inner diameter 142 mm, outer diameter 146 mm, length 135 mm) used as rectifying cylinders were prepared. A total of eight slits (width 5 mm, length 25 mm) were formed at one end of each of these flow straightening tubes as follows. That is, a set of slits formed by two slits formed at intervals of 2 mm was provided at four positions that divide the circumference into four equal parts. Four rectifications were provided on the side surface of the rectifying cylinder, and these ridges were joined to the inner surface of the cylindrical case to fix the rectifying cylinder to both ends of the cylindrical case in advance. In addition, the two rectifying cylinders were fixed in the cylindrical case so that the opening of the upper nozzle was at an intermediate position between the two slit groups (see FIG. 2).

  Four small bundles formed by wrapping 1750 hollow fiber membranes with a polyethylene net were prepared. The hollow part was closed to a position of about 2 mm from both ends of the hollow fiber membrane. Thereafter, four small bundles were inserted into a rectifying cylinder provided in a cylindrical case, and a thermosetting epoxy resin was injected from both ends by a centrifugal casting method to solidify it. When inserting a yarn bundle composed of four small bundles into the rectifying cylinder, the position of the recess formed between the two small bundles was made to coincide with the position of the slit of the rectifying cylinder. A hollow fiber membrane module was produced by heating to 50 ° C. and curing, cutting both ends of the hollow fiber membrane, and opening the hollow portion of the hollow fiber membrane. This hollow fiber membrane module had a length of 1045 mm and an effective membrane length of 930 mm. A pipe connection cap made of polysulfone was joined to both end faces of the hollow fiber membrane module via O-rings. The distance between the end faces of both pipe connection caps was 1180 mm.

<Water flow test>
Using the hollow fiber membrane module, an apparatus having the same configuration as the internal pressure filtration apparatus shown in FIG. 4 was constructed. A rotor type flow meter was provided on the downstream side of the valve V3 of the circulating water discharge pipe L3 and on the downstream side of the valve V2 of the filtered water discharge pipe L2. In addition, an ultrasonic flow meter is provided at a position before the filtrate water discharge pipe L2b joins the upper pipe L2a so that the flow rate of water discharged from the lower nozzle 2b through the pipe L2b can be measured.

Water flow was started by adjusting the degree of opening of the valves V1 and V3 so that the filtered water flow rate was 10 m ³ / hr and the circulating water amount was 0.3 m ³ / hr. When the air in the module was replaced with water, the entire module was replaced with water, and no residual bubbles were observed. In addition, the valve V2 was fully opened at the time of water flow.

(Measurement of module water permeability)
Then, the filtered water flow rate while fixing the circulating water to 0.3 m ³ / hr is ^{15m 3 / hr, 20m 3 /} hr, 25m 3 / hr, has achieved stepwise through water such that ^{30 m} 3 / hr It was. The indicated values of the pressure gauges Pi, Po, and Pf at each stage were read to determine the transmembrane pressure difference. The transmembrane pressure difference ΔP (MPa) is calculated by the following equation (6), where Pi is the pressure of the water to be treated, Po is the pressure of the circulating water, Pf is the pressure of the filtered water, and H is the height correction value. Value. The height correction value H (MPa) is a value calculated by the following formula (7) when the height from the floor surface of each measurement position of Pi, Po, Pf is Hi, Ho, Hf [m]. is there.

A graph of each filtrate water amount and transmembrane pressure difference was drawn, and the filtrate water flow rate when the transmembrane pressure difference was 0.1 MPa was determined to be 27 m ³ /hr/0.1 MPa @ 25 ° C. This value is the module water permeability. From this value and the module dimensions (outer diameter 170 mm, length 1180 mm), the module water permeability was calculated as 1010 m ³ /hr/0.1 MPa / m ³ . This value is about 2 to 1.7 times the water permeability of the modules described in Non-Patent Documents 1 and 2. In addition, when the flow rate from the lower nozzle was measured while passing through each filtered water flow rate, the flow rate from the lower nozzle showed almost 1/2 of the filtered water flow rate, and almost the same amount from the upper and lower nozzles. It was confirmed that the filtered water was flowing out.

(Leak inspection)
Subsequently, water flow was continuously performed for 1 month under conditions of a circulating water amount of 0.3 m ³ / hr and a filtrate water flow rate of 30 m ³ / hr. One month later, the module was removed from the apparatus, and a leak test was performed as follows. That is, after removing the pipe connection caps at both ends, the module was immersed in a water tank to fill the interior with pure water. Next, the nozzle on one side was sealed with a stopper, and an air pipe was connected to the other nozzle. Air pressure was gradually applied to 0.2 MPa, and both ends of the module were observed to confirm whether or not air bubbles continued to emerge from the hollow portion. The module according to this example had no leakage at all. The module weighed 34 kg when the internal water was completely dripped, and could be carried alone.

(Observation inside the module)
The module was cleaved at a position where a small hole of the flow straightening cylinder was formed, and the inside was observed. When the dimensions of the eight small holes formed at the fixed interface position of the upper flow straightening tube were measured, the equivalent diameter was within the range of 3 to 7 mm. The reason why the equivalent diameter is not a constant value is that the interface position varies in the circumferential direction, and the height of the small hole varies depending on the location. The total opening area S ₃ of the small holes was 160 mm ² , and the opening area S ₁ at the tip of the rectifying cylinder was 5800 mm ² . The opening area ratio S ₃ / S ₁ was 0.03. Moreover, the opening of the front-end | tip part of a rectification | straightening cylinder was located in 125 mm-118 mm from the interface of a fixing | fixed part. When the distance between the small hole of the flow straightening cylinder and the hollow fiber membrane at the outermost peripheral part of the yarn bundle was measured, all of the eight small holes were located in the range of 5 to 8 mm.

[Example 2]
Except for the following points, a hollow fiber membrane module according to this example was produced in the same manner as in Example 1. That is, instead of a cylinder with a total of eight slits, a cylinder with three slits (width 8 mm) formed so as to be unevenly distributed in a predetermined region in the circumferential direction was used as the upper rectifying cylinder, and This is the point that 7000 hollow fiber membranes are bundled as one bundle into the rectifying cylinder without dividing the yarn bundle into four small bundles (see FIG. 8). When performing centrifugal casting, the nozzle was set so that the nozzles faced in the horizontal direction and the slit provided in the flow straightening tube was on the upper side. A filtration apparatus was configured using the hollow fiber membrane module having the configuration shown in FIG. 8, and tests and evaluations were performed in the same manner as in Example 1.

  When a water flow test was started and the air in the module was replaced with water, the entire module was replaced with water, and no residual bubbles were observed.

The module according to this example had a module water permeability of 25 m ³ /hr/0.1 MPa @ 25 ° C. This value and the module size (OD 170 mm, length 1180 mm) from the module water permeability was calculated to 930m ³ /hr/0.1MPa/m ^3. Also in this example, almost the same amount of filtered water was flowing out from the upper and lower nozzles as in Example 1.

In addition, when a leak inspection was conducted after continuously passing water for one month, there was no leak at all. After the leak inspection, the module was cleaved and the inside was observed. When the dimensions of the three small holes formed at the fixed interface position of the rectifying cylinder were measured, the equivalent diameter was within the range of 7 to 10 mm. The total opening area S ₃ of the small holes was 150 mm ² , and the opening area S ₁ at the tip of the rectifying cylinder was 5800 mm ² . The opening area ratio S ₃ / S ₁ was 0.03. Moreover, the opening of the front-end | tip part of a rectification | straightening cylinder was located in 127 mm-120 mm from the interface of a fixing | fixed part. When the distance between the small hole of the rectifying tube and the hollow fiber membrane at the outermost peripheral portion of the yarn bundle was measured, all three small holes were located in the range of 5 to 7 mm.

[Example 3]
Except for the following points, a hollow fiber membrane module according to this example was produced in the same manner as in Example 1. That is, instead of a cylinder having a constant diameter, a cylindrical member whose diameter increases downward is used, and a rectifying cylinder having three openings formed on its side surface is used (see FIG. 7). The flow straightening cylinder used in this example has the following shape. The slit for forming the small hole was the same as that of the rectifying cylinder in the first embodiment.
Inner diameter / outer diameter of the base end: 142 mm / 146 mm,
Inner diameter / outer diameter of tip portion: 154 mm / 158 mm,
Length: 85mm,
Upper side / lower side / height / number of openings: 100 mm / 100 mm / 20 mm / 3 pieces,
Position of the upper side of the opening: 25 mm from the end face of the tip.

  A filtration apparatus was configured using the hollow fiber membrane module having the configuration shown in FIG. 7, and tests and evaluations were performed in the same manner as in Example 1. The rectifying cylinder was arranged in the cylindrical case so that there was no opening within a range of 45 ° to the left and right with respect to the central axis of the nozzle.

  When a water flow test was started and the air in the module was replaced with water, the entire module was replaced with water, and no residual bubbles were observed.

The module according to this example had a module water permeability of 27 m ³ /hr/0.1 MPa @ 25 ° C. From this value and the module dimensions (outer diameter 170 mm, length 1180 mm), the module water permeability was calculated as 1010 m ³ /hr/0.1 MPa / m ³ . Also in this example, almost the same amount of filtered water was flowing out from the upper and lower nozzles as in Example 1.

Moreover, when water was passed continuously for one month and then a leak inspection was performed, there was no leak at all. After the leak inspection, the module was cleaved and the inside was observed. When the dimensions of the eight small holes formed at the fixed interface position of the rectifying cylinder were measured, the equivalent diameter was within the range of 4 to 9 mm. The total opening area S ₃ of the small holes was 220 mm ² , and the opening area S ₁ at the tip of the rectifying cylinder was 6000 mm ² . The opening area ratio S ₃ / S ₁ was 0.04. Moreover, the opening of the front-end | tip part of a rectification | straightening cylinder was located 50 mm-56 mm from the interface of the fixing | fixed part. When the distance between the small hole of the flow straightening cylinder and the hollow fiber membrane at the outermost peripheral part of the yarn bundle was measured, all of the eight small holes were located in the range of 5 to 8 mm.

[Reference Example 1]
A hollow fiber membrane module according to this reference example was produced in the same manner as in Example 1 except that a rectifying tube without a slit was used. A filtration device was constructed using this hollow fiber membrane module, and tests and evaluations were carried out in the same manner as in Example 1.

When water flow was started, it was observed that bubbles having a size of several centimeters remained in the vicinity of the fixed part interface and between the small bundles. With the circulating water amount fixed at 0.3 m ³ / hr, the flow rate was increased stepwise so that the filtrate water flow rate was 15 m ³ / hr, 20 m ³ / hr, 25 m ³ / hr, and 30 m ³ / hr. However, the remaining bubbles remained at the above position without flowing out of the rectifying cylinder. Furthermore, water flow was continued for 1 month under the condition of 30 m ³ / hr, but almost no change was observed in the residual amount and position of bubbles. In order to analyze the bubble remaining position, the position where the bubble remained on the surface of the cylindrical case was marked.

  After the water flow test, the module was cleaved and the distance between the inner surface of the rectifying tube and the hollow fiber membrane at the outermost periphery of the small bundle was measured, and the range where the small bundle contacted the rectifying tube was in the range of 1 to 3 mm. On the other hand, in the portion where the bubbles remained, the distance between the inner surface of the rectifying tube and the hollow fiber membrane at the outermost periphery of the small bundle was 5 mm or more. From this, it was found that bubbles do not collect in a portion where the distance between the inner surface of the flow straightening cylinder and the hollow fiber membrane on the outermost periphery of the yarn bundle is narrower than 5 mm, but bubbles easily collect in a portion separated by 5 mm or more. Comparing the results of this reference example and Example 1, it was shown that it is extremely useful to reduce the remaining bubbles in the module by providing small holes at locations where the above-mentioned intervals of 5 mm or more are likely to accumulate.

[Reference Example 2]
A hollow fiber membrane module according to the present reference example was produced in the same manner as in Example 1 except that the direction of the yarn bundle was shifted by 45 ° when the yarn bundle was inserted into the flow straightening cylinder. That is, the rectifying cylinders were fixed to both ends of the yarn bundle so that the small holes of the rectifying cylinders were located not in the recesses between the two small bundles but in the center of each small bundle. A filtration device was constructed using this hollow fiber membrane module, and tests and evaluations were carried out in the same manner as in Example 1.

When water flow was started, it was observed that bubbles having a size of several centimeters remained in the vicinity of the fixed part interface and between the small bundles. With the circulating water amount fixed at 0.3 m ³ / hr, the flow rate was increased stepwise so that the filtrate water flow rate was 15 m ³ / hr, 20 m ³ / hr, 25 m ³ / hr, and 30 m ³ / hr. However, the remaining bubbles remained at the above position without flowing out of the rectifying cylinder. Furthermore, water flow was continued for 1 month under the condition of 30 m ³ / hr, but almost no change was observed in the residual amount and position of bubbles. After the water flow test, the module was cleaved and the distance between the small holes formed in the flow straightening cylinder and the hollow fiber membrane on the outermost periphery of the small bundle was measured, and all of the eight small holes were in the range of 1 to 3 mm.

[Reference Example 3]
A hollow fiber membrane module according to this reference example was produced in the same manner as Example 1 except for the following points. That is, instead of using a cylinder with a total of eight slits as the upper and lower rectifier cylinders, a cylinder without a slit is used as the lower rectifier cylinder, and the same slit as in the first embodiment is used. This is the point where the cylinder formed with is used as the upper flow straightening cylinder. Using this hollow fiber membrane module, an apparatus having the same configuration as the external pressure filtration apparatus shown in FIG. 5 was constructed. A rotor type flow meter was provided on the downstream side of the valve V7 of the circulating water discharge pipe L7 and on the downstream side of the valve V6 of the filtered water discharge pipe L6.

Water flow was started by adjusting the opening of the valves V5 and V7 so that the flow rate of filtered water was 10 m ³ / hr and the amount of circulating water was 0.3 m ³ / hr. Water was continuously passed for one month under the conditions of a filtrate water flow rate of 30 m ³ / hr and a circulating water amount of 0.3 m ³ / hr. In addition, the valve V6 was fully opened at the time of water flow. One month later, the module was removed from the apparatus, and a leak test was performed in the same manner as in Example 1. As a result, 28 hollow fiber membranes leaked.

  When the module was disassembled and the leak position was observed, the hollow fiber membrane in the outermost peripheral part of the yarn bundle was broken near the lower fixed part interface. The positional relationship between the shape of the small hole and the yarn bundle, and the positional relationship between the flow straightening tube and the yarn bundle (distance between the inner surface of the flow straightening tube and the hollow fiber membrane at the outermost peripheral portion of the yarn bundle, etc.) there were.

[Reference Example 4]
A hollow fiber membrane module according to this reference example was produced in the same manner as in Example 2 except that a cylinder having a large number of through holes as shown in FIG. 11 was used as the upper flow straightening cylinder (FIGS. 9 and 10). reference). The shape of this flow straightening cylinder is as follows.
Inner diameter / outer diameter of cylinder: 148 mm / 154 mm,
Length: 85mm,
Diameter / pitch / arrangement / total number of through-holes: 5 mm / 10 mm / 7 rows 36 columns / 252.

  A filtration apparatus was configured using the hollow fiber membrane module having the configuration shown in FIGS. 9 and 10, and tests and evaluations were performed in the same manner as in Example 1. Note that the flow straightening cylinder was arranged in the cylindrical case so that there was no through hole within a range of 45 ° to the left and right with respect to the central axis of the nozzle.

  When a water flow test was started and the air in the module was replaced with water, the entire module was replaced with water, and no residual bubbles were observed.

The module according to this reference example had a module water permeability of 20 m ³ /hr/0.1 MPa @ 25 ° C. This value and the module size (OD 170 mm, length 1180 mm) from the module water permeability was calculated to 750m ³ /hr/0.1MPa/m ^3. In this reference example, the flow rate from the upper nozzle was about ½ of the flow rate from the lower nozzle.

A ball valve was attached in the middle of the filtrate discharge pipe L2b, and the flow rate from each of the upper and lower nozzles was adjusted to 15 m ³ / hr by adjusting the opening, and water was continuously passed for one month. When water was continuously passed for one month and then a leak test was conducted, five hollow fiber membranes were leaking. After the leak inspection, the module was disassembled and the leak position was observed. As a result, the hollow fiber membrane at the outermost peripheral portion of the yarn bundle was broken near the upper fixed portion interface. The hollow fiber membrane that had been damaged was within a range of 1 to 2 mm from the through hole of the flow straightening cylinder, and was present at a position close to the through hole.

  When the dimension of the through hole formed at the fixed portion interface position of the upper rectifying cylinder was measured, the equivalent diameter was in the range of 2 to 5 mm. The through hole that is closer to the center of the module than the fixed part interface position and closest to the fixed part interface was located 5 mm from the interface position.

  According to the hollow fiber membrane module of the present invention and the filtration method using the same, it is possible to stably obtain a large amount of water with good water quality. Since the hollow fiber membrane module of this invention can be made into a compact size, it is particularly suitable as a security filter for use in ultrapure water production facilities. The hollow fiber membrane module is also suitable as a pyrogen removal filter for use in water for injection production facilities.

  DESCRIPTION OF SYMBOLS 1 ... Yarn bundle, 1a ... Hollow fiber membrane, 1b ... Small bundle, 2 ... Cylindrical case, 2a, 2b ... Nozzle, 3a, 3b ... Fixed part, 4, 5 ... Rectification cylinder, 4a, 5a ... Base of rectification cylinder End part, 4b, 5b ... The tip part of the rectification cylinder, 4c ... Small hole, 4d ... Slit, 10, 20 ... Hollow fiber membrane module, 14 ... Rectification cylinder, 14a ... Base end part of the rectification cylinder, 14b ... Tip of the rectification cylinder Part, 14c ... opening, 100, 200 ... filtration device, Fa, Fb ... interface of fixed part.

Claims (5)

A yarn bundle composed of a number of hollow fiber membranes;
A cylindrical case containing the yarn bundle and having a nozzle on a side surface;
A pair of fixing parts made of a casting agent that seals the outer surfaces of the hollow fiber membranes and the gap between the outer surface and the inner surface of the cylindrical case at both ends of the yarn bundle in the cylindrical case;
A pair of rectifying cylinders, one end of which is sealed by the fixing portion and extending so as to surround both ends of the yarn bundle;
With
The pair of rectifying cylinders each have an opening through which water inside the rectifying cylinder can flow to the nozzle at a position spaced apart from the fixed portion.
At least one of the flow straightening tubes is a hollow fiber membrane module having a small hole having an equivalent diameter of 1 mm or more and 10 mm or less penetrating from an outer surface to an inner surface of the flow straightening tube at an interface position of the fixed portion.   2. The hollow fiber membrane module according to claim 1, wherein the small hole is provided at a portion where a distance between an inner surface of the flow straightening cylinder and a hollow fiber membrane forming the outermost surface of the yarn bundle is 5 mm or more.   The rectifying cylinder having the small hole has a slit having a width of 1 mm or more and 10 mm or less extending in the longitudinal direction from the one end, and the small hole is formed by embedding a part of the slit by the fixing portion. The hollow fiber membrane module according to claim 1 or 2, which is a product.   The yarn bundle is formed by bundling a plurality of small bundles formed by bundling a plurality of hollow fiber membranes in the cylindrical case in parallel, and at least at the interface position of the fixed portion compared with other portions. The hollow fiber membrane module as described in any one of Claims 1-3 which has a part with the low packing density of the said hollow fiber membrane. A step of installing the hollow fiber membrane module according to any one of claims 1 to 4 so that the small hole provided in the rectifying cylinder is disposed above;
Supplying the water to be treated to the hollow portion of the hollow fiber membrane from below the module;
Collecting filtered water flowing out of the hollow fiber membrane from the nozzle of the cylindrical case;
A filtration method comprising:

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