JPH06178917A - Hollow fiber membrane module - Google Patents

Abstract

PURPOSE:To obtain a hollow fiber membrane unit of external pressure type where there is no entanglement of hollow fiber membranes and which is washed with high efficiency by dividing a hollow fiber membrane group into plural slave bundles and fastening the free end of each bundle or its vicinity together with a fastening member. CONSTITUTION:One end 21 of a hollow fiber membrane group 2 is fixed and supported on a resin partition 3 which a resin is injected into one end of a cylindrical case 1 to form and one end 211 of the hollow fiber membrane is opened to the outside surface of the resin partition 3. On the other hand, the other end 212 of the hollow fiber membrane is closed and made in a free state. Further the hollow fiber membrane group 2 is divided into plural slave bundles 20 and each bundle 20 is fastened by a fastening member 4 at the free end. Therefore since the external force is borne by all the slave bundles, the rigidity of the hollow fiber membrane to bending and torsional external force is high and the entanglement of the hollow fiber membranes is not easily caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber membrane module used for liquid filtration and the like.

[0002]

2. Description of the Related Art A membrane module is sometimes used for filtration, purification, concentration of a stock solution or recovery of valuable materials. There are various types of membrane modules, but in particular, in the hollow fiber membrane module, the membrane area per unit volume can be increased, and in particular, in the external pressure type, the internal pressure type is used. In comparison, it is more frequently used because it is advantageous in terms of pressure loss and cleaning.

In a membrane module, a decrease in filtration flow rate due to membrane contamination with time is unavoidable, and it is necessary to wash the membrane at appropriate times to maintain the filtration flow rate at a certain value or more. Conventionally, as a method for cleaning the bundle of hollow fiber membranes of external pressure type, air is injected from one end of the case while the case of the membrane module is filled with the stock solution, and the outer surface of the membrane is exposed to the air-mixed liquid flow. The so-called air-scrubbing method, the backwashing method in which the filtered water in the filtered water storage tank is pressure fed into the hollow fiber membrane, and the like are known.

[0004]

However, among the hollow fiber membrane modules, one end of the hollow fiber membrane bundle is fixedly supported,
When the external pressure type hollow fiber membrane module with the other end free is washed by the above air-scrubbing method and backwashing method,
The individual hollow fiber membranes move in a disorderly manner, and the hollow fiber membranes are entangled with each other, so that the membrane is easily damaged.

In order to solve such a problem, it has been proposed that the outer periphery of the hollow fiber membrane bundle is closely covered with a flexible porous protective body without interposing a gap (Japanese Patent Laid-Open No. 59-59).
No. 147603). This proposal is to wrap the hollow fiber membrane bundle in a protective body and eliminate the movement of the hollow fiber membranes intertwined with each other.The stronger the tightening of the hollow fiber membrane bundle by the protective body, the more the hollow fiber membrane It is effective in eliminating such movements.

However, if the hollow fiber membrane bundle is wrapped with a protective body, it becomes difficult to maintain a gap between the hollow fiber membranes, and in the case of the air-scrubbing method, an air-mixed liquid flow is generated in the hollow fiber membrane bundle. It becomes difficult to flow along the thread film, and a decrease in cleaning efficiency cannot be avoided.

An object of the present invention is to provide an external pressure type hollow fiber membrane module which can be highly efficiently washed by the air-scrubbing method even if one end of the hollow fiber membrane bundle is in a free state, without entanglement of the hollow fiber membranes. To provide.

[0008]

In the hollow fiber membrane module of the present invention, a hollow fiber membrane group is housed in a case, one end of the hollow fiber membrane group is fixed, and the other end is free. In the membrane module, the hollow fiber membrane group is divided into a plurality of child bundles, and the free end of each child bundle or a portion in the vicinity thereof is bound by a binding member.

[0009]

The hollow fiber membrane is a synthetic resin body having a diameter of about 1 mm, and exhibits a considerable elastic behavior. When an external force acts on one hollow fiber membrane of the child bundle, the force passes through the bundling portion and the other hollow fibers. The hollow fiber membrane has a high rigidity against bending or twisting external force as a result of acting on the membrane and the external force being carried by the entire child bundle.
Entanglement of the hollow fiber membrane is less likely to occur.

Further, there is a sufficient gap between the hollow fiber membrane child bundles, and even in one child bundle, the bundling is local, and in the portion other than this bundling, there is a usual gap between the hollow fiber membranes. Therefore, at the time of air-scrubbing cleaning, the air-mixed liquid flow is made to flow along these gaps, and efficient film cleaning can be performed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the present invention. In FIG. 1, 1 is a vertical cylindrical case. 2 is a cylindrical case 1
In the hollow fiber membrane group housed inside, the outer diameter of the hollow fiber is usually 0.02 to 2 mmφ, and the number is from several tens to several thousands. As the hollow fiber membrane, any of a microfiltration membrane, an ultrafiltration membrane, and a reverse osmosis separation membrane can be used, and examples thereof include polyvinyl alcohol-based, polyolefin-based, polysulfone-based, polyacrylonitrile-based, and polyamide-based polymers. − Is used.

Reference numeral 3 denotes a resin partition wall (epoxy type, urethane type, silicone type) provided by injecting resin into one end of the cylindrical case 1.
(A single layer or a laminated layer) of a curable resin such as resin, and one end 21 of the hollow fiber membrane group 2 is fixedly supported on this resin partition wall 3, and one end 211 of the hollow fiber membrane is attached to the outer surface of the resin partition wall 3. It is open. On the other hand, the other end 212 of the hollow fiber membrane is occluded (for this occlusion, a resin such as a silicone-based or urethane-based resin is infiltrated by utilizing a capillary phenomenon, or the inside of the hollow fiber membrane is sucked and decompressed to the same level as above. The method of immersing a resin can be used), and it is in a free state. Further, the hollow fiber membrane group 2 is provided with a plurality of child bundles 20, ...
And each child bundle 20 is bound by the binding member 4 at the free end (the other end).

Reference numeral 11 is a raw water inlet provided at the other end of the cylindrical case 1. Denoted at 31 are a plurality of raw water outflow holes provided at equal intervals in the resin partition wall 3, the number of which is 1 to 10
It is said that

Reference numeral 5 is a joint, and a partition wall 51 is used to form the raw water chamber a.
To a filtered water chamber b, and a raw water distribution pipe 52, ... Is pierced through the partition wall 51 in a watertight manner. A concentrated raw water outlet 53 is provided in the raw water chamber a and a filtered water outlet 54 is provided in the filtered water chamber b. Are provided respectively. The joint 5 is connected to one end of the tubular case 1 by a V band or the like, and the raw water flow pipe 52 is watertightly inserted into the raw water outflow hole 31 of the resin partition wall 3 through an O ring (not shown). is there.

In this external pressure type hollow fiber membrane module, raw water is supplied from the raw water inlet 11 into the case 1,
In the case 1, the raw water is filtered by the hollow fiber membrane group 2, and the filtered water appearing in the hollow fiber membrane by this filtration is taken out from the filtered water outlet 54 through the filtered water chamber b of the joint 5. .

On the other hand, the raw water concentrated by the above-mentioned filtration passes through the raw water outflow hole 31 and the raw water distribution pipe 52, and then the joint 5
Out of the concentrated raw water outlet 53. Further, the backwashing method and the air-scrubbing method are used together for the membrane cleaning. The external pressure type hollow fiber membrane module is usually installed in a vertical orientation, and air is injected into the case 1 from the raw water inlet 11 at the lower end of the case during air scrubbing cleaning.

With the injection of the air, the air-mixed liquid flow comes into contact with the hollow fiber membrane, and the hollow fiber membrane bundle 20 tends to exhibit a complicated deformation in which bending deformation and twisting deformation are combined. Since the free ends of the fiber bundles 20 are bound, the hollow fiber membranes of each fiber bundle are not independently deformed, and the bending force and the twisting force are shared by all the hollow fiber membranes forming the fiber bundle. As a result, the bending deformation and the twisting deformation of the hollow fiber membranes can be sufficiently suppressed, and the entanglement of the hollow fiber membranes can be well prevented.

There is a sufficient gap between the above-mentioned child bundles 20, and the length of the binding portion in each child bundle is only a part of the total length, and between the hollow fiber membranes of other portions is usually. Since there are the passing gaps, the air-mixed liquid flow can be made to flow along these gaps during the air-scrubbing cleaning, and the hollow fiber membranes can be efficiently washed.

In the present invention, the binding material is a net or porous body having a mesh or a pore size sufficiently large so that the raw water can be brought into contact with the hollow fiber membrane of the child bundle portion covered with the binding material without staying. It is preferable to use a plastic such as polyethylene, polypropylene or the like, an elastic net such as rubber or polyurethane, or a porous sheet.

These binding materials have elasticity and can be attached to the hollow fiber membrane child bundle with a relatively small tightening force, and a certain amount of space is maintained between the hollow fiber membranes of the bundle portion at the bundle portion. be able to.

The gap between the hollow fiber membranes in the bundled portion of the child bundle is smaller than the gap between the hollow fiber membranes in the other bundled portions, and if the length of the bundled portion of the child bundle is too long, the whole bundle will be Since the gap between the hollow fiber membranes in the child bundle is reduced and the cleaning efficiency is reduced, the length of the binding portion of the child bundle is the effective length of the child bundle (from the inner surface of the resin partition wall to the free end). It is reasonable to set the length to 30% or less (1% minimum from the viewpoint of binding).
Is necessary).

In the hollow fiber membrane binding of the present invention, it is preferable that the binding material is mounted on the child bundle with the smallest possible tightening force. In this case, in order to prevent the binding material from being pulled out from the child bundle, As shown in FIG. 2, it is preferable to mount the binding material 4 at a position slightly above the free end e of the child bundle 20.

However, in the portion of the length L, the hollow fiber membranes are independently bent or twisted and deformed, and if the length L is made too long, the entanglement of the hollow fiber membranes is caused in this portion. It is appropriate that the length L is 50 cm or less.

In the present invention, the larger the number of hollow fiber membranes constituting the child bundle, the higher the degree of increase in bending or torsional rigidity, which is advantageous in preventing the entanglement of the hollow fiber membranes. Since the outer diameter of the child bundle becomes large and it becomes difficult to bring the inside of the child bundle into contact with the air-mixed liquid flow during the air-scrubbing cleaning, the cleaning efficiency is deteriorated, and thus the hollow child bundle is formed. The number of thread membranes is preferably 30 to 100 (usually about 3 to 10 bundles).

In the hollow fiber membrane module of the present invention,
Membrane damage due to entanglement of hollow fiber membranes can be eliminated and the membrane can be washed by the air-scrubbing method, and filtration can be performed at a high filtration flow rate and a high salt removal rate. This is also clear from the comparison between the following examples and comparative examples.

Example 1 An acrylic resin case having an inner diameter of 126 mmφ, a thickness of 7 mm and a length of 1000 mm was placed in an outer diameter of 1.60 mmφ and a thickness of 0.4.
Accommodating 1000 0 mm polysulfone hollow fiber membranes,
One end of the case is closed with a cap that has inserted 7 pins for forming the stock solution passage holes, and the whole case is set in a centrifugal casting machine with one end of the case facing down, and epoxy resin adhesive is injected into one end of the case. Then, a resin partition was formed by centrifugal casting, and one end of the hollow fiber membrane was opened on the surface of the resin partition.

Then, the hollow fiber membrane group was divided into five child bundles, and the free ends were bound with polyethylene nets (length is 10% of the effective length of the hollow fiber membranes). Further, after the completion of the centrifugal casting, the inside of the hollow fiber membrane was sucked and decompressed, and urethane resin was infiltrated into the other end of the hollow fiber membrane by 25 mm to close the other end.

Example 2 The same as Example 1 except that the number of child bundles was 10.

Example 3 The same as Example 1 except that the total number of hollow fiber membranes was 1600 and the number of child bundles was 8.

Comparative Example Same as Example 1 except that no polyethylene net was used. 2. With respect to each of these example products and comparative example products, with the above-described vertical installation, the case was filled with water, and the air flow rate from the raw water inlet port at the lower end of the case, 3.
When air-scrubbing cleaning was performed for 1 month under the conditions of 0 Nm ³ / h, ventilation for 1 minute and stop for 5 seconds.
No entanglement of the hollow fiber membranes and no membrane damage were observed, but in the comparative example product, entanglement of the hollow fiber membranes was observed, and five membrane breakages (breakages) were observed.

[0031]

EFFECTS OF THE INVENTION The hollow fiber membrane module of the present invention is constructed as described above, and since the sub-bundles of the hollow fiber membranes are bound together, the rigidity of the hollow fiber membrane against bending or twisting can be increased. Even if the hollow fiber membranes are washed by the air-scrubbing method, bending or twisting deformation of the hollow fiber membranes can be well prevented, and the entanglement of the hollow fiber membranes and the membrane damage due to this entanglement can be sufficiently prevented.

Further, since there is a sufficient gap between the child bundles and a usual gap exists in the portion other than the binding portion of the child bundles, during the film cleaning by the air-scrubbing method, these gaps are formed. A sufficient flow of air-mixed liquid flow enables effective membrane cleaning.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 Case 11 Raw Water Inlet 2 Hollow Fiber Membrane Group 20 Hollow Fiber Membrane Bundle 211 One End of Hollow Fiber Membrane 212 Other End of Hollow Fiber Membrane 4 Bundling Member 3 Resin Partition 53 Concentrated Raw Water Outlet 54 Filtered Water Outlet

Claims (2)

[Claims] 1. A membrane module in which a hollow fiber membrane group is housed in a case, one end of the hollow fiber membrane group is fixed, and the other end is in a free state. A hollow fiber membrane module characterized in that it is divided into child bundles, and the free ends of the child bundles or a portion in the vicinity thereof are bound by a binding member. 2. The hollow fiber membrane module according to claim 1, wherein the binding member is a net or a porous body.