JPH11197461A - Hollow fiber membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow fiber membrane module preventing the generation of the membrane damage caused by the vibration displacement of hollow fiber membranes while ensuring high treatment capacity. SOLUTION: The outer periphery of a part of a hollow fiber membrane bundle 2 formed by bundling a large number of hollow yarn membranes is covered with an elastic tube 4 made of rubber or the like and a part of elastic tube 4 is embedded in a fixing part 3 comprising a resin layer and the hollow fiber membrane module is fixed to the fixing part 3 so that the remaining part of the tube 4 is exposed to the interior of a cylindrical case 1. The elastic tube 4 is formed so as to have an inner diameter slightly smaller than the outer diameter of the hollow fiber membrane bundle 2. A hole is formed to the part where the elastic tube 4 is embedded in the fixing part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hollow fiber membrane module used for separating components in a liquid.

[0002]

2. Description of the Related Art Various separation membrane modules such as a hollow fiber membrane module, an annular membrane module, a spiral membrane module, and a pleated membrane module are used to separate components in a liquid. In particular, the hollow fiber membrane module has advantages such as a large membrane area per unit volume (volume efficiency), a simple seal between the undiluted solution and the permeated solution, and a small number of types of constituent members and a small size. Therefore, it is used in various fields such as ultrafiltration, reverse osmosis, dialysis, and crystal separation.

[0003] A hollow fiber membrane module generally forms a single hollow fiber membrane bundle by bundling a large number of thin hollow fiber membranes at substantially equal intervals, accommodating a plurality of hollow fiber membrane bundles in a case,
At least one end of the hollow fiber membrane bundle is bonded and fixed to the case with a resin. In addition, the end of each hollow fiber membrane is formed in an open state on the end face of the fixing portion that is bonded and fixed.

In such a hollow fiber membrane module,
An external pressure type hollow fiber membrane module is one that uses the outside of the hollow fiber membrane as a stock solution flow path.

[0005] In the external pressure type hollow fiber membrane module, since a large number of hollow fiber membranes are densely arranged in a cross section, a gap between the hollow fiber membranes is narrow, and the hollow fiber membrane has a resistance when a stock solution flows. Therefore, a hollow fiber membrane module capable of performing uniform membrane separation over the entire hollow fiber membrane bundle has been proposed.

FIGS. 4 and 5 are sectional views of a conventional external pressure type hollow fiber membrane module. FIG. 4 shows a module of a type in which the permeated liquid permeating the hollow fiber membrane bundle is taken out to both ends of the cylindrical case, and FIG. 5 shows a type in which the permeated liquid permeating the hollow fiber membrane bundle is taken out to one end side of the cylindrical case. Module.

In the hollow fiber membrane module shown in FIG. 4, a plurality of thin hollow fiber membranes are bundled into one at substantially equal intervals to form a hollow fiber membrane bundle 2.
1, the hollow fiber membrane bundle 21 is housed in the cylindrical case 20, and both ends of the hollow fiber membrane bundle 21 are fixed to the fixing portions 22 at both ends of the cylindrical case 20 with a resin adhesive. ing. On the outer surface of the fixing portion 22, the end face of each hollow fiber membrane is formed so as to be open.

The hollow fiber membrane module shown in FIG. 5 is formed by fixing only one end of a hollow fiber membrane bundle 31 to a fixing portion 22 formed at one end of a cylindrical case 20.

In the hollow fiber membrane module shown in FIGS. 4 and 5, a hollow fiber membrane bundle is divided into a plurality of portions by disposing a partition plate 23 in a fixed portion 22. By providing a gap at the center of the hollow fiber membrane bundle using this partition plate 23,
The stock solution easily flows into the central portions of the hollow fiber membrane bundles 21 and 31, and uniform membrane separation can be performed over the entire hollow fiber membrane bundles 21 and 31.

[0010]

However, the external pressure type hollow fiber membrane module is operated so that the stock solution flowing outside the hollow fiber membrane is in a turbulent state and the film resistance on the surface of the hollow fiber membrane is reduced. . For this reason, the hollow fiber membrane is easily vibrated with the flow of the stock solution. Further, in the external pressure type hollow fiber membrane module, a suspended substance easily adheres to the outer surface of the hollow fiber membrane. For this purpose, an air bubbling process for continuously injecting air into the case is performed, and the hollow fiber membrane is vibrated to perform membrane cleaning.

When the hollow fiber membrane is vibrated, a shearing force or a bending moment acts on the interface between the hollow fiber membrane and the fixing portion, and the hollow fiber membrane may be broken or broken. . In particular, in the hollow fiber membrane module shown in FIGS. 4 and 5, the hollow fiber membrane was easily damaged. FIG.
FIG. 6 is a partially enlarged view of the hollow fiber membrane module shown in FIGS. 4 and 5. In the hollow fiber membrane module of FIGS. 4 and 5, the partition plate 23 is embedded inside the fixing part 22. For this reason, the hollow fiber membrane 21 a facing the gap 40 between the hollow fiber membranes formed by the partition plate 23 is easily deformed toward the gap 40, and the other side of the gap 40 is hindered from deformation by the adjacent hollow fiber membrane. Can be

When the hollow fiber membrane bundle 21 is vibrated by air bubbling for cleaning the membrane, the hollow fiber membrane 21a particularly adjacent to the gap 40 is greatly deformed toward the gap 40, and such deformation is repeated. It is. For this reason, the bending action is repeatedly applied to the vicinity of the boundary between the hollow fiber membrane 21a and the fixing portion 22, and there is a problem that the root A of the hollow fiber membrane is damaged.

Therefore, in order to prevent such damage to the hollow fiber membrane, there is provided a method for preventing the vibration of the hollow fiber membrane by providing a rectifying cylinder for rectifying the flow state of the stock solution in the vicinity of the fixed portion of the hollow fiber membrane. A method of reducing the concentration of stress on the root of the hollow fiber membrane by providing a polymer material layer such as rubber having elasticity at the interface with the fixing part of the hollow fiber membrane, A method of winding the net to suppress the vibration of the hollow fiber membrane has been proposed. However, even with these methods, damage to the hollow fiber membrane could not be sufficiently prevented.

An object of the present invention is to provide a hollow fiber membrane module which ensures high processing performance and does not cause membrane breakage due to vibration of the hollow fiber membrane bundle.

[0015]

In the hollow fiber membrane module according to the present invention, a hollow fiber membrane bundle formed by bundling a plurality of hollow fiber membranes is housed in a case, and at least one end of the hollow fiber membrane bundle is provided. In the hollow fiber membrane module whose part is fixed to the fixing part provided on the end part side of the case, the outer periphery of a part of the fixing part side of the hollow fiber membrane bundle is covered with an elastic body, and a part of the elastic body is part of the case. And the remaining part of the elastic body is embedded in the fixing part.

In the hollow fiber membrane module according to the present invention, a part of the elastic body covering the outer periphery of the hollow fiber membrane bundle is embedded in the fixed part, and the remaining part is exposed in the case. For this reason, the outer periphery of the hollow fiber membrane bundle extending from the inside of the fixed portion to the inside of the case is bundled by the elastic body,
Each hollow fiber membrane is less likely to deform independently, and the rigidity of the entire hollow fiber membrane bundle is improved. For this reason, when the undiluted solution is introduced in a turbulent state or when air is introduced during air bubbling, each hollow fiber membrane bundle of the hollow fiber membrane bundle is deformed individually and greatly, and the root portion near the fixing portion is deformed. Large stress is prevented from being generated. This prevents membrane breakage due to vibration of the hollow fiber membrane bundle.

Preferably, the elastic body is formed of a cylindrical elastic tube. In this case, a plurality of hollow fiber membranes can be bundled by inserting them into a cylindrical elastic tube. This increases the rigidity of the hollow fiber membrane bundle near the fixed portion, and allows the hollow fiber membrane bundle to be gently deformed by the elasticity of the elastic tube. This prevents concentration of stress on the interface between the hollow fiber membrane bundle and the fixed portion, thereby preventing the hollow fiber membrane bundle from being damaged.

In particular, a hole may be formed in a portion embedded in the fixed portion of the elastic tube. In this case, the material of the fixing portion is directly adhered to the hollow fiber membrane through the hole, and the bonding between the hollow fiber membrane bundle and the fixing portion becomes strong.

Further, an undiluted solution supply port may be provided at a portion on the fixed portion side of the case. In this case, when the undiluted solution is introduced into the case from the undiluted solution supply port, the undiluted solution flows through the vicinity of the portion of the hollow fiber membrane bundle covered with the elastic body and flows through the case. At this time, even when the hollow fiber membrane bundle vibrates due to the flow of the undiluted solution, concentration of stress at the root of the hollow fiber membrane bundle covered with the elastic body is suppressed, and membrane breakage is prevented.

Further, the ends of the plurality of hollow fiber membranes on the fixed portion side are opened to the outside of the fixed portion, and the other end portions of the plurality of hollow fiber membranes are sealed to be free in the case, and the case is closed. A concentrate outlet may be provided at a portion opposite to the fixing portion.

In this case, the stock solution introduced from the stock solution supply port flows along the hollow fiber membrane bundle, and is taken out from the concentrated solution outlet. At that time, even if the hollow fiber membrane bundle whose one end is in a free state and the other end is fixed in the fixed portion vibrates, stress is prevented from being concentrated on the root portion of the hollow fiber membrane bundle covered with the elastic body. Thereby, the breakage of the hollow fiber membrane bundle is prevented.

[0022]

1 is a sectional view of an external pressure type hollow fiber membrane module according to the present invention, and FIG. 2 is an external view of a hollow fiber membrane bundle. The external pressure type hollow fiber membrane module of FIG. 1 includes a plurality of hollow fiber membrane bundles 2 housed in a cylindrical case 1. A stock solution supply port 1a is formed on a side surface of the cylindrical case 1, a concentrated liquid outlet 1b is formed at one end of the cylindrical case 1, and a permeate liquid outlet 1c is formed at the other end.

The hollow fiber membrane bundle 2 is formed by bundling a large number of thin hollow fiber membranes at substantially equal intervals, and covering a part of the outer periphery of the membrane bundle with an elastic tube 4 made of rubber or the like. The end of the hollow fiber membrane bundle 2 covered with the elastic tube 4 is formed by casting a thermosetting resin such as urethane resin or epoxy resin into the end of the cylindrical case 1 on the side of the permeated liquid outlet 1c. Fixed part 3
It is embedded and fixed inside. The other end of the hollow fiber membrane is sealed and is free in the cylindrical case 1.

A hole 5 is formed in the surface of the elastic tube 4, and a part of the elastic tube 4 including the hole 5 is embedded in the fixed part 3. Thereby, the fixing part 3 and the hollow fiber membrane are directly contacted via the hole 5 and fixed.

The elastic tube 4 is formed in a cylindrical shape having an inner diameter smaller by about 5% than the outer diameter of the bundle of the plurality of hollow fiber membranes. The material of the elastic tube 4 is selected in consideration of the resistance to the properties of the stock solution to be treated. For example,
The elastic tube 4 has a hardness of 1 according to a JIS-A rubber hardness meter.
It consists of 0-50 rubber. Here, the elastic tube 4 corresponds to the elastic body of the present invention.

The number of bundles of the hollow fiber membrane bundles 2 is set to an appropriate number in consideration of the inner diameter of the cylindrical case 1 and the complexity of the bundling operation, and is preferably, for example, within 20 bundles.

In the hollow fiber membrane module shown in FIG. 1, the stock solution flows from the stock solution supply port 1a of the cylindrical case 1 in a direction crossing the hollow fiber membrane bundle 2, and thereafter flows along the longitudinal direction of the hollow fiber membrane bundle 2. Then, it is concentrated and flows out from the concentrated liquid outlet 1b of the cylindrical case 1. The permeate that has passed through the hollow fiber membrane of the hollow fiber membrane bundle 2 during the flow of the undiluted solution flows from the opening of the hollow fiber membrane opened at the end face of the fixing part 3 to the permeate outlet 1c side, and is taken out to the outside. It is.

As described above, near the stock solution supply port 1a, the stock solution flows in a direction intersecting the longitudinal direction of the hollow fiber membrane bundle 2. For this reason, the hollow fiber membrane bundle 2 is vibrated in a direction orthogonal to the longitudinal direction of each hollow fiber membrane, and receives a shearing force and a bending moment. On the other hand, in the hollow fiber membrane bundle 2, the base protruding from the fixing part 3 is covered with the elastic tube 4. For this reason, even when vibration is applied by the stock solution flowing from the stock solution supply port 1a, the elastic tube 4 elastically supports the hollow fiber membrane bundle 2 to reduce deformation. This prevents each hollow fiber membrane of the hollow fiber membrane bundle 2 from being significantly deformed and broken or damaged.

[0029]

EXAMPLES Here, external pressure type hollow fiber membrane modules of Examples and Comparative Examples were prepared, and the presence or absence of breakage of the hollow fiber membrane due to vibration displacement of the hollow fiber membrane was compared.

In the hollow fiber membrane module of the embodiment shown in FIG. 1, first, a hollow fiber membrane made of polysulfone having an outer diameter of 1.8 mm is used.
000 pieces were divided into 20 bundles of 100 pieces each. Next, a candy rubber tube having an outer diameter of 25 mm was cut into a length of 50 mm, and three holes having a diameter of 5 mm were formed 10 mm from one end. Then, the 100 hollow fiber membrane bundles are covered with a candy rubber tube so that a hole is located at a position 50 mm from one end of one of the hollow fiber membrane bundles to form the hollow fiber membrane bundle 2, and 20 hollow fiber membrane bundles 2 are further collected. It was housed in a cylindrical case 1 having an outer diameter of 5 inches.

The hollow fiber membrane bundle 2 was bonded and fixed to the inside of the cylindrical case 1 only by centrifugal casting using epoxy resin at only the end on the side covered with the candy rubber tube. After casting, cure the epoxy resin and add extra epoxy resin from the end
It was cut and removed by 0 mm. Thereby, each hollow fiber membrane of the hollow fiber membrane bundle is opened at the end face of the cut epoxy resin. Further, about 10 mm of the candy rubber tube of the hollow fiber membrane bundle is embedded in the fixing portion 3 made of epoxy resin, and the remaining 40 mm portion is exposed in the cylindrical case 1 from the interface with the fixing portion 3. ing. In addition, the fixing part 3 of each hollow fiber membrane
The other end is sealed with epoxy resin. The sealed end of each hollow fiber membrane is a free end.

FIG. 3 is a sectional view of a hollow fiber membrane module of a comparative example. The hollow fiber membrane module of the comparative example shown in FIG. 3 is different from the hollow fiber membrane module of the example in that no candy rubber tube is used.

The hollow fiber membrane modules of Examples and Comparative Examples were vertically arranged such that the outlet of the concentrated liquid was directed upward, and the pressure was 2 kg / cm ² and the air flow rate was 4 Nm ³ / h from the undiluted solution supply port.
Air bubbling for introducing air continuously for 500 hours into the hollow fiber membrane module was performed under the conditions described above, and then an air leak test was performed to check whether or not the hollow fiber membrane was damaged.

As a result of the above test, two and finally five membrane breakages occurred in the hollow fiber membrane module of the comparative example by 100 hours after the start of the test. No damage occurred. Further, a 300-hour air bubbling test was additionally performed on the hollow fiber membrane module of the example, but no membrane breakage occurred.

As described above, by covering the hollow fiber membrane bundle with the elastic tube and embedding a part of the elastic tube in the fixed portion, it is possible to suppress the hollow fiber membrane bundle from being largely deformed due to vibration. The occurrence of breakage of the hollow fiber membrane can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of an external pressure type hollow fiber membrane module according to the present invention.

FIG. 2 is an external view of a hollow fiber membrane bundle of the hollow fiber membrane module of FIG.

FIG. 3 is a cross-sectional view of a hollow fiber membrane module according to a comparative example.

FIG. 4 is a cross-sectional view showing an example of a conventional hollow fiber membrane module.

FIG. 5 is a cross-sectional view showing another example of a conventional hollow fiber membrane module.

FIG. 6 is an enlarged view near a partition plate in FIGS. 5 and 6;

[Explanation of symbols]

 Reference Signs List 1 cylindrical case 2 hollow fiber membrane bundle 3 fixed layer 4 elastic tube 5 hole

Claims (5)

[Claims] 1. A hollow fiber membrane bundle formed by bundling a plurality of hollow fiber membranes is accommodated in a case, and at least one end of the hollow fiber membrane bundle is fixed to a fixing portion provided on an end side of the case. In the hollow fiber membrane module, the outer periphery of a part of the hollow fiber membrane bundle on the fixed portion side is covered with an elastic body, a part of the elastic body is exposed in the case, and a remaining part of the elastic body is A hollow fiber membrane module embedded in the fixing part. 2. The hollow fiber membrane module according to claim 1, wherein said elastic body comprises a cylindrical elastic tube. 3. The hollow fiber membrane module according to claim 2, wherein a hole is formed in a portion of the elastic tube embedded in the fixed portion. 4. The hollow fiber membrane module according to claim 1, wherein an undiluted solution supply port is provided in a portion of the case on the fixed portion side. 5. The end of the plurality of hollow fiber membranes on the side of the fixed portion is open to the outside of the fixed portion, and the other ends of the plurality of hollow fiber membranes are sealed to be free in the case. The hollow fiber membrane module according to claim 4, wherein a concentrated liquid outlet is provided at a portion of the case opposite to the fixing portion.