JPH11179162A - Hollow fiber membrane module and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a membrane from being bent or broken caused by vibration of a hollow fiber membrane. SOLUTION: The end part of a bundle 1 of hollow fiber membranes is fixed by casting it with an adhesive and the circumference of the fixed part of the bundle 1 of the hollow fiber membranes is surrounded by an elastic body 3 and a heat shrinkable tube 4. The heat shrinkable tube 4 is shrunk by heating to bring the elastic body 3 into contact with the outer peripheral face of the bundle 1 of the hollow fiber membranes. The elastic body 3 supports the hollow fiber membranes 1a by pressing the hollow fiber membranes 1a in such an extent that the hollow fiber membranes 1a are not crushed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hollow fiber membrane module used for separating components in a liquid and a method for producing the same.

[0002]

2. Description of the Related Art Hollow fiber membrane modules are used for solid-liquid separation such as recovery of valuable materials in an aqueous solution, removal of cladding during condensate water, or wastewater treatment. A hollow fiber membrane module having a separation active layer formed outside the hollow fiber membrane is used as an external pressure type. In the external pressure type hollow fiber membrane module, the undiluted solution comes into contact with the outer surface of the hollow fiber membrane, the permeated liquid that has passed through the membrane cross section is guided to the hollow part in the membrane, and is taken out of the module from the open end of the hollow fiber membrane.

[0003] In such an external pressure type hollow fiber membrane module, a contaminant adheres to the outer surface of the hollow fiber membrane to form a contaminated layer. When the contaminant layer is formed, the filtration ability of the hollow fiber membrane decreases. For this purpose, a cleaning treatment for removing a contaminated layer from the outer surface of the hollow fiber membrane is periodically performed. A typical method of the cleaning process is air scrubbing cleaning. In the air scrubbing cleaning, a gas such as air is introduced into the stock solution passage of the hollow fiber membrane module. The introduced gas becomes bubbles and rises in the module. The hollow fiber membrane is vibrated by the gas-liquid flow generated at this time, and the contaminant layer attached to the surface of the hollow fiber membrane is peeled off. Thereby, the filtration ability of the hollow fiber membrane is restored.

In the hollow fiber membrane module, the end of the hollow fiber membrane is cast and fixed to the end of the case by using a potting method or a centrifugal method. In the vicinity of the interface between the hollow fiber membrane and the fixed part, the casting resin rises along the outer surface of the hollow fiber membrane by about several mm to several cm. When the hollow fiber membrane in such a state is vibrated during air scrubbing cleaning,
A bending moment acts on the hollow fiber membrane with the tip of the fixed portion rising along the hollow fiber membrane as a fulcrum, and the membrane often breaks.

In order to prevent the above-mentioned film breakage, a resin having a relatively low hardness after curing is used as a resin for casting.
For example, a device using an elastic epoxy resin, a silicone resin, a urethane resin, or the like has been devised. However, such resins also increase in hardness due to aging, and the effect of preventing film breakage cannot be obtained gradually.

On the other hand, there has been proposed a structure in which a hollow fiber membrane is prevented from breaking using an elastic annular body. FIG. 3 is a schematic view of a main part of a conventional hollow fiber membrane module, and such a hollow fiber membrane module is disclosed in Japanese Utility Model Laid-Open No. 4-137732. The hollow fiber membrane module of FIG. 3 has a hollow fiber membrane bundle 1 in which a large number of hollow fiber membranes 1a are bundled and is fixed by being embedded in a fixed layer 2. An annular body 5 is attached so as to surround the outer periphery of the film bundle 1. The annular body 5 has a circular cross section so that no corners are formed inside.

In the vicinity of the fixed layer 2 of the hollow fiber membrane bundle 1, an annular body 5
Is attached, the hollow fiber membrane 1
When a is bent by receiving vibration, the fulcrum of the bending moment moves from the interface position between the fixed layer 2 and the hollow fiber membrane bundle 1 to the mounting position of the annular body 5. In the vicinity of the attachment position of the annular body 5, each hollow fiber membrane 1a has uniform elasticity and strength. Therefore, even when a bending moment acts on the hollow fiber membrane bundle 1 with the attachment position of the annular body 5 as a fulcrum, the stress due to the bending moment is evenly distributed to the hollow fiber membrane 1a at the attachment position of the annular body 5, and the membrane breaks. Is prevented from occurring.

[0008]

However, the annular body 5 shown in FIG. 3 keeps the position on the hollow fiber membrane bundle 1 by tightening the hollow fiber membrane bundle 1 by its own elastic force. Therefore, when the hollow fiber membrane bundle 1 vibrates, the position of the annular body 5 may move. Then, depending on the position of the moved annular body 5, the effect of preventing the hollow fiber membrane 1a from breaking may be lost.

In order to prevent the annular body 5 from moving,
A method of embedding and fixing a part of the annular body 5 in the fixing layer 2 is also conceivable. However, the annular body 5 is attached in advance so that the hollow fiber membrane bundle 1 is sufficiently fastened. For this reason, when the end of the hollow fiber membrane bundle 1 and the annular body 5 clamped by the annular body 5 and the annular body 5 are embedded and fixed in the casting resin, the packing density of the hollow fiber membrane 1a is extremely high. Poor filling of the casting resin into the gap occurs, and the incidence of manufacturing defects increases.

It is an object of the present invention to provide a hollow fiber membrane module capable of preventing membrane breakage caused by vibration of a hollow fiber membrane, and a method of manufacturing the same.

[0011]

In the hollow fiber membrane module according to the present invention, the hollow fiber membrane bundle is housed in the case, and at least one end of the hollow fiber membrane bundle is connected to the end of the case. In the hollow fiber membrane module fixed to the provided resin fixing portion, the elastic member is fixed to the resin fixing portion so as to surround the outer periphery of the hollow fiber membrane bundle on the resin fixing portion side, and the elastic member is fixed to the hollow fiber membrane bundle. The outer periphery of the elastic member is covered with a heat-shrinkable member so as to contact the outer peripheral surface of the elastic member.

In the hollow fiber membrane module according to the present invention, the elastic member is in contact with the outer peripheral surface of the hollow fiber membrane bundle near the resin fixing portion. When the hollow fiber membrane bundle is subjected to a bending moment due to vibration, for example, during washing of the hollow fiber membrane module, the position of the fulcrum of the bending moment in the hollow fiber membrane is not the interface between the hollow fiber membrane and the resin fixing portion, but the elasticity. At the contact position of the member, the hollow fiber membrane vibrates while being supported by the elastic member. The elastic member flexibly supports the hollow fiber membrane while allowing the displacement of the hollow fiber membrane according to its own elasticity.
Thereby, the concentration of stress due to the bending moment in the hollow fiber membrane is suppressed, and the membrane can be prevented from breaking.

Further, the elastic member is brought into contact with the outer peripheral surface of the hollow fiber membrane by the heat shrinkable member. The heat-shrinkable member contracts when heated, and presses and deforms the elastic member by the contraction force. After the contraction, the elastic member keeps its deformation. By using such a heat-shrinkable member, the contact state of the elastic member can be adjusted without using a complicated member, the manufacturing process is simplified, and the hollow fiber membrane module can be manufactured at low cost. .

In particular, the resin from the resin fixing portion rises along the outer surface of the hollow fiber membrane bundle in the vicinity of the resin fixing portion, and the length of the elastic member projecting from the resin fixing portion into the case is fixed to the resin fixing portion. It is preferable that the length is longer than the rising length of the resin from the portion.

In this case, when the hollow fiber membrane bundle receives a bending moment due to vibration, the position serving as a fulcrum of the bending moment in the hollow fiber membrane is determined by the interface between the hollow fiber membrane and the rising portion of the resin from the resin fixing portion. Instead, the hollow fiber membrane vibrates while being supported by the elastic member. Thereby, the hollow fiber membrane is flexibly supported, and the occurrence of membrane breakage is prevented.

In particular, it is preferable that the heat-shrinkable member is formed of an annular heat-shrinkable tube, one end of the heat-shrinkable tube is embedded in the resin fixing portion, and the other end is located on the outer peripheral surface of the elastic member. In this case, the end of the heat-shrinkable tube is prevented from directly contacting the outer peripheral surface of the hollow fiber membrane bundle. For this reason, it is possible to prevent the angular end of the heat-shrinkable tube after contraction from coming into contact with the surface of the hollow fiber membrane bundle and causing the membrane to break.

In the method for manufacturing a hollow fiber membrane module according to the present invention, the hollow fiber membrane bundle is housed in a case, and at least one end of the hollow fiber membrane bundle is attached to a resin fixing portion provided at an end of the case. A method of manufacturing a fixed hollow fiber membrane module, wherein an outer periphery of at least one end of the hollow fiber membrane bundle is surrounded by an elastic member, an outer periphery of the elastic member is covered by a heat shrinkable member, and at least one end of the hollow fiber membrane bundle is covered. The elastic member and a part of the heat-shrinkable member are embedded in the resin fixing portion, the heat-shrinkable member is heated to shrink, and the elastic member is brought into contact with the outer peripheral surface of the hollow fiber membrane bundle.

In the method for manufacturing a hollow fiber membrane module according to the present invention, the outer periphery of at least one end of the hollow fiber membrane bundle is surrounded by an elastic member, and the outer periphery of the elastic member is covered with a heat-shrinkable member. , And at least one end of the hollow fiber membrane bundle is embedded and fixed in the resin fixing portion together with a part of the elastic member and the heat shrinkable member. Then, the heat contraction member is contracted by heating. The contracted heat-shrinkable member deforms the elastic member so that the elastic member comes into contact with the outer peripheral surface of the hollow fiber membrane, and maintains the state. And
The hollow fiber membrane bundle is flexibly supported to prevent the hollow fiber membrane from breaking.

By using such a heat-shrinkable member, the elastic member can be attached without using a complicated manufacturing process, the manufacturing process is simplified, and the hollow fiber membrane module can be manufactured at low cost. .

[0020]

1 and 2 are schematic views showing the structure of a main part of a hollow fiber membrane module according to the present invention. FIG. 1 shows a state before heat treatment of a heat shrinkable tube. Indicates the state after the heat treatment.

1 and 2, in the hollow fiber membrane module, one end of a hollow fiber membrane bundle 1 in which a number of thin hollow fiber membranes 1a are bundled at substantially equal intervals is cast into an end of a cylindrical case. It is fixed to a fixing layer 2 made of a thermosetting resin such as urethane resin or epoxy resin. The opening at the end of each hollow fiber membrane 1a is exposed at the outer end face 2a of the fixed layer 2 made of the cured thermosetting resin. The other end of the hollow fiber membrane 1a is sealed.

The hollow fiber membrane 1a is made of a material such as polysulfone, polyethersulfone, polyamide, polyimide, polyvinyl alcohol, polyethylene, polypropylene and the like. A cylindrical elastic body 3 is arranged near the end of the hollow fiber membrane bundle 1 on the fixed layer 2 side. One end of the elastic body 3 is embedded in the fixed layer 2, and the other end is
It protrudes into the case from inside. A heat-shrinkable tube 4 is attached to the outer periphery of the elastic body 3.

The elastic body 3 is formed of urethane foam, styrene paper, or the like, and is arranged with a small gap from the outer peripheral surface of the hollow fiber membrane bundle 1. Heat shrink tube 4 is PVC
It is made of a (polyvinyl chloride) -based, olefin-based, or fluororesin-based material. The elastic body 3 can be brought into contact with the outer periphery of the hollow fiber membrane bundle 1 during heat shrinkage, and can be pressurized to the extent that the hollow fiber membrane does not collapse. The one with the contraction rate is selected. In the heating step, heat treatment conditions according to the above-described conditions are set.

Here, the fixing layer 2 corresponds to the resin fixing portion of the present invention, the elastic body 3 corresponds to an elastic member, and the heat-shrinkable tube 4 corresponds to a heat-shrinkable member.

The hollow fiber membrane module having the above structure is
It is manufactured by the following steps. First, in FIG. 1, a large number of hollow fiber membrane bundles 1a are bundled and temporarily fixed.
The elastic body 3 and the heat-shrinkable tube 4 are attached to one end of the case and inserted into the case. Then, a liquid thermosetting resin is cast into the case, and a curing process is performed to form the fixed layer 2. Thereby, one end of the hollow fiber membrane bundle 1, the elastic body 3,
A part of the heat-shrinkable tube 4 is embedded in the fixed layer 2.

When the elastic body 3 and the heat-shrinkable tube 4 are fixed in the fixed layer 2, the heat-shrinkable tube 4 is heated as shown in FIG. By heating at a temperature selected according to the heat shrink property of the heat shrink tube 4 for a predetermined time, the heat shrink tube 4 shrinks, and the elastic body 3 is pressed against the outer periphery of the hollow fiber membrane bundle 1 and brought into contact therewith. Thus, the elastic body 3 elastically supports the outer peripheral surface of the hollow fiber membrane bundle 1 near the fixed layer 2.

In the hollow fiber membrane module configured as shown in FIG. 2, the fulcrum of the bending moment acting on the hollow fiber membrane 1a when the hollow fiber membrane 1a is subjected to vibration during air scrubbing cleaning is determined by the contact of the elastic body 3. Position. This elastic body 3
In the vicinity of the hollow fiber membrane bundle 1 in contact with the hollow fiber membranes 1a
Are integrally bundled, so that the elasticity and strength of the hollow fiber membrane 1a are made uniform. For this reason, the bending moment due to the vibration of the hollow fiber membrane is reduced by the hollow fiber membrane 1 near the contact portion of the elastic body 3.
a, and the stress caused by the bending moment is prevented from being concentrated. For this reason, the breakage of the hollow fiber membrane is prevented.

The length of the protrusion of the heat-shrinkable tube 4 from the surface of the fixed layer 2 is shorter than the length of the protrusion of the elastic body 3. This prevents the tip of the heat-shrinkable tube 4 from directly contacting the outer peripheral surface of the hollow fiber membrane bundle 1. This prevents the end of the heat-shrinkable tube 4 where the corners are easily formed from coming into contact with the outer peripheral surface of the hollow fiber membrane bundle 1 and causing the membrane to break.

Further, usually, at the time of casting, the resin agent rises along the surface of the hollow fiber membrane.
It is about several mm to several cm from the surface of the fixed layer 2. Therefore, by making the length of the heat-shrinkable tube 4 and the elastic body 3 protruding from the fixed layer 2 longer than the length of the rising portion of the resin agent on the surface of the hollow fiber membrane, the fulcrum of the bending moment of the elastic body 3 The contact position. Thereby, the effect of preventing the hollow fiber membrane from breaking can be enhanced.

[0030]

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

The hollow fiber membrane module of the embodiment has an elastic body made of polyurethane sponge on the outer periphery of a membrane bundle of 2800 polysulfone hollow fiber membranes having an inner diameter of 0.7 mm, an outer diameter of 1.2 mm and a length of 1200 mm; Soft PV around the periphery
C. A heat-shrinkable tube (manufactured by Mitsubishi Plastics, Inc.) is placed, and a hollow fiber membrane bundle is introduced into a polysulfone pipe having an inner diameter of 100 mm and a length of 1020 mm.
The hollow fiber membrane bundle was fixed at both ends of the polysulfone pipe by casting with epoxy resin. Further, after the epoxy resin was sufficiently cured, the hollow fiber membrane module was held in a hot air circulation type dryer at a temperature of 100 ° C. for 5 minutes to perform a heat treatment. Thereby, the heat-shrinkable tube was shrunk.

Further, the hollow fiber membrane module of the comparative example was manufactured to have a structure in which the heat shrink tube was removed from the hollow fiber membrane module of the above example.

With respect to the hollow fiber membrane modules of the examples and comparative examples, scrubbing air was continuously introduced into the modules at a flow rate of 2.5 Nm ³ / hour from a PVC pipe for gas introduction, and the film breaking resistance was evaluated. .

As a result, in the hollow fiber membrane module of the comparative example, seven hollow fiber membranes were broken at the outer periphery of the hollow fiber membrane bundle after 12 hours, whereas in the hollow fiber membrane module of the example, After elapse of 550 hours, no breakage of the hollow fiber membrane occurred. From this result, it was found that the hollow fiber membrane module of the example had a high effect of preventing membrane breakage.

As described above, in the hollow fiber membrane module according to the present invention, since the elastic body supports the outer peripheral surface of the hollow fiber membrane bundle at a position away from the interface with the fixed layer, bending caused by vibration of the hollow fiber membrane is achieved. The stress due to the moment is prevented from being concentrated on the interface between the hollow fiber membrane and the fixed layer, whereby the hollow fiber membrane can be prevented from breaking.
This makes it possible to use the hollow fiber membrane module safely for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state before heat treatment in a hollow fiber membrane module according to the present invention.

FIG. 2 is a schematic view showing a state after heat treatment in a hollow fiber membrane module according to the present invention.

FIG. 3 is a schematic view showing a main part of a conventional hollow fiber membrane module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow fiber membrane bundle 1a Hollow fiber membrane 2 Fixed layer 3 Elastic body 4 Heat shrinkable tube

Claims (4)

[Claims] 1. A hollow fiber membrane module in which a hollow fiber membrane bundle is housed in a case, and at least one end of the hollow fiber membrane bundle is fixed to a resin fixing portion provided at an end of the case. An elastic member is fixed to the resin fixing portion so as to surround the outer periphery of the hollow fiber membrane bundle on the resin fixing portion side, and the elastic member is so arranged that the elastic member contacts the outer peripheral surface of the hollow fiber membrane bundle. A hollow fiber membrane module, wherein the outer periphery of the hollow fiber membrane module is covered with a heat shrinkable member. 2. The elastic member protruding from the resin fixing portion along the outer surface of the hollow fiber membrane bundle in the vicinity of the resin fixing portion, and protruding into the case from the resin fixing portion. The hollow fiber membrane module according to claim 1, wherein a length of the resin is larger than a rising length of the resin from the resin fixing portion. 3. The heat-shrinkable member comprises an annular heat-shrinkable tube, one end of the heat-shrinkable tube being embedded in the resin fixing portion, and the other end being located on the outer peripheral surface of the elastic member. The hollow fiber membrane module according to claim 1 or 2, wherein: 4. Manufacture of a hollow fiber membrane module in which a hollow fiber membrane bundle is housed in a case, and at least one end of the hollow fiber membrane bundle is fixed to a resin fixing portion provided at an end of the case. A method comprising surrounding an outer periphery of at least one end of the hollow fiber membrane bundle with an elastic member, covering an outer periphery of the elastic member with a heat-shrinkable member, and covering the at least one end of the hollow fiber membrane bundle with the elastic member and the thermal member. The hollow fiber membrane module according to claim 1, wherein the heat shrinkable member is shrunk by heating, and the elastic member is brought into contact with an outer peripheral surface of the hollow fiber membrane bundle. Production method.