JP2552939Y2 - Vertical hollow fiber membrane module - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical hollow fiber membrane module used for purification and separation of raw water.

[0002]

2. Description of the Related Art A module using a hollow fiber membrane module has a large membrane area per unit volume, which is advantageous for downsizing the module. In particular, the vertical hollow fiber membrane module is advantageous for improving the processing capacity per unit installation space, for example, for condensate purification processing in a nuclear power plant, a thermal power plant, etc. It is used in the field of ultrapure water production.

FIG. 3 shows an example of use of a conventional vertical hollow fiber membrane module. In FIG. 3, M 'denotes a vertical hollow fiber membrane module, and a hollow fiber membrane bundle 2' is provided in a vertical protection cylinder 1 '.
And a communication pipe 3 'are accommodated therein. Resin partitions 4a', 4b 'are formed at the upper and lower ends of the protective cylinder 1', and the hollow fiber membrane 2 'is formed on the upper surface of the upper resin partition 4a' and the lower surface of the lower resin partition 4b '. Each end and each end of the communication pipe 3 'are opened, and raw water supply holes 51' and 52 'are provided in the protective cylinder 1'. Reference numeral 61 'denotes an upper fitting attached to the upper end of the protective tube 1' via an O-ring. The upper fitting 61 'and the tube plate 62' allow the hollow fiber membrane module M 'to be inserted into the pressure vessel 63'. Suspended support.

In the above module, the pressurized container 6
Raw water is press-fitted into the protective cylinder 1 'from the raw water inlet 64' of the 3 'via the raw water supply holes 51' and 52 ', filtered by the hollow fiber membrane 2', and the filtered permeated water is collected in the hollow fiber membrane 2 '. The water is guided upward and downward, and the downward permeated water is once collected by the cap 7 ′, further guided upward through the communication pipe 3 ′, and merged with the upward permeated water flow.

[0005] In the filtration treatment, the filtration performance decreases due to the adhesion of the scale to the membrane surface with the continuation of the filtration operation. Therefore, it is necessary to perform the membrane cleaning timely. Therefore, in the above module, the gas introduction nozzle 8
1 'through a gas receiver 82' to a gas inlet 83 '.
The gas is further fed into the protection cylinder 1 ′, and the gas thus introduced is turned into bubbles to rise. The gas-liquid mixed flow of the bubbles and the liquid (raw water) is supplied to a hole (raw water supply hole) 51 ′ on the top of the protection cylinder 1 ′. Drained from
The hollow fiber membrane 2 'is swung by the convection of the raw water by the rising bubbles,
The scale attached to the surface of the hollow fiber membrane is peeled off, and the scale
The membrane is washed by a so-called air-scrubbing method in which the gas is discharged from a hole (raw water supply hole) 52 'at the lower part of the protective cylinder.

[0006]

SUMMARY OF THE INVENTION The above hollow fiber membrane module
When forming a resin partition wall, the resin penetrates into the gaps of the hollow fiber membrane bundle by capillary action, and the root of the hollow fiber membrane becomes hard, so that brittleness is inevitable. Further, when the hollow fiber membrane in the resin partition comes into contact with the inner surface of the protective cylinder, the adhesive strength between the protective cylinder and the resin partition decreases, so that the outer periphery of the hollow fiber membrane bundle in the resin partition and the inner peripheral surface of the protective cylinder are reduced. It is necessary to keep a predetermined distance between the outer circumference (usually 5 to 10 mm), and a considerable space is formed between the outer periphery of the hollow fiber membrane bundle and the inner surface of the protective tube. Is a free space that allows the hollow fiber membrane to bend and deform.

[0007] In the membrane cleaning by the air-scrubbing method, a gas-liquid mixed flow is generated by the gas introduced into the protective cylinder, and the gas-liquid mixed flow flows out of a hole in the upper part of the protective cylinder. However, if this hole is close to the lower surface of the upper resin partition wall, the gas-liquid mixed flow collides with the root portion of the hollow fiber membrane that has been embrittled by the capillary action of the resin, and the hollow fiber membrane portion breaks. easy.

When the outlet hole at the upper portion of the protective cylinder is provided at a position separated from the upper resin partition wall or the surface to some extent, the gas-liquid mixed flow can collide with the hollow fiber membrane portion which is not embrittled. Because of the inherent flexibility of the membrane, the collision force of the gas-liquid mixed flow can be absorbed, the deformation of the brittle hollow fiber membrane root can be mitigated well, and the above-mentioned membrane damage can be prevented.

However, air-scrubbing gas accumulates between the outflow hole in the protective cylinder and the lower surface of the upper resin partition wall, and the hollow fiber membrane portion in this space is exposed to the accumulated gas for a long time to be in a dry state. The membrane performance is reduced.
For example, in the case of hydrophobic membranes such as polysulfone and polyethylene, the permeability is imparted by hydrophilization and immersion treatment with ethanol or the like, but the hydrophilicity is lost due to contact with air for a long time, and water is removed. It cannot pass through.

It is an object of the present invention to provide a method for cleaning a membrane by an air-scrubbing method. An object of the present invention is to provide a vertical hollow fiber membrane module that can prevent breakage due to a mixed flow.

[0011]

The vertical hollow fiber membrane module of the present invention accommodates a hollow fiber membrane bundle in a vertical protection cylinder and forms an upper resin partition at least at the upper and lower ends of the protection cylinder. In the hollow fiber membrane module having the hollow fiber membrane fixed thereto, a hole A is provided in the protective cylinder adjacent to the lower surface of the upper resin partition wall, and the hole cross-sectional area is slightly lower than the hole A and smaller than the hole A. Hole B having a large diameter.
Is 1 to 10 times the outer diameter of the hollow fiber membrane, and the uppermost end of the hole B is located 2 to 3 cm from the lower surface of the upper resin partition.

[0012]

When the membrane is cleaned by the air-scrubbing method, the hole A having a small cross-sectional area exhibits a high resistance to the outflow of the gas-liquid mixed flow, and the gas-liquid mixed flow mainly flows out of the hole B, The gas-liquid mixed flow flows sufficiently away from the lower surface of the resin partition wall to avoid direct impact of the gas-liquid mixed flow on the root of the hollow fiber membrane that has become brittle due to the capillary action of the resin. Since the holes A are provided, gas pools in the protective cylinder can be eliminated, and a decrease in film performance due to drying of the film can be avoided.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a sectional view of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a protection cylinder. Reference numeral 2 denotes a bundle of hollow fiber membranes housed in the protective cylinder 1, for example, a polysulfone, polyethylene membrane, or the like. Reference numeral 3 denotes a communication pipe inserted into the hollow fiber membrane bundle, which has a significantly lower flow resistance than the hollow fiber membrane.
4a is an upper resin partition, 4b is a lower resin partition, seals the space between the hollow fiber membrane 2 and the protection cylinder 1, and is provided on the upper surface of the upper resin partition 4a and the lower surface of the lower resin partition 4b. The end and each end of the communication pipe 3 are opened. Numeral 40 indicates the root portion of the hollow fiber membrane to which the resin adhered due to the capillary phenomenon when the resin partition wall was formed, and this portion 40 has become less brittle because of the inherent flexibility of the membrane (shear strength has been reduced to about half). doing). 5 is a cap attached to the lower end of the protective cylinder 1 in a watertight manner,
6 is an air receiver.

A is a hole provided in the protective cylinder 1 adjacent to the lower surface 41 of the upper partition wall 4a, and the diameter of the hole is made as small as possible within a range that can prevent gas from accumulating in the protective cylinder. Usually, it is 1 to 10 times the outer diameter of the hollow fiber membrane.
Are holes provided below the position of the hole A, and the total cross-sectional area of the holes is sufficiently larger than the hole A. This hole B is formed by membrane cleaning by the air-scrubbing method.
It is provided at a position sufficiently separated from the lower surface 41 of the upper resin partition wall so that the lateral flow of the gas-liquid mixed flow in the upper portion of the protective cylinder does not directly collide with the above-described brittle hollow fiber membrane base portion 40. Usually, the upper end of the uppermost hole in the hole B is located at a position separated from the lower surface 41 of the upper resin partition by 2 to 3 cm (if too far, it becomes difficult to clean the film near the lower surface of the upper resin partition). The total cross-sectional area of the hole B is set so as to generate a gas-liquid mixing flow rate appropriate for air-scrubbing.

Reference numeral 7 denotes a gas introduction hole for introducing air-scrubbing gas into the protection tube 1, and 8 denotes a scale discharge hole.

In order to clean the vertical hollow fiber membrane module, an air scrubbing method is used. Thus,
Gas from a gas introduction nozzle (not shown) is supplied to an air receiver 6.
Through the gas introduction hole 7 and into the protective cylinder 1, the supplied gas is bubbled, and the rising bubbles generate a gas-liquid mixed flow, mainly through the hole B having a large hole cross-sectional area. The hollow fiber membrane 2 flows out of the protective cylinder 1 during this time, convection occurs in the protective cylinder 1 and the hollow fiber membrane 2 is rocked, and the scale attached to the surface of the hollow fiber membrane is peeled off. And is discharged from the nozzle discharge hole 8.

In this case, a horizontal flow of the gas-liquid mixed flow is generated in the upper part of the protection cylinder 1, and the hole B for controlling the position of this flow is formed.
(In the hole A, the hole cross-sectional area is small, exhibiting a large resistance to the gas-liquid mixed flow, and the gas-liquid mixed flow substantially flows toward the hole B.) The gas-liquid mixed flow can be made to collide with the membrane portion in the normal state where the root portion 40 of the hollow fiber membrane, which has been embrittled by the above-described capillary action, has been removed, and the collision location and the embrittlement Due to the inherent flexibility of the membrane in the normal state between the membrane and the membrane, the impact force of the gas-liquid mixed flow can be well absorbed, and the brittle hollow fiber membrane base around the hollow fiber membrane bundle where free space exists Breakage (crack or break) can be prevented well.

Further, since the hole A is provided at a position adjacent to the lower surface 41 of the upper resin partition wall of the protection cylinder 1, it is possible to prevent the air-scrubbing gas from staying in the upper part of the protection cylinder, and the air in the upper part of the protection cylinder is prevented. The occurrence of accumulation can be prevented, and therefore, a decrease in film performance due to drying of the film in the air accumulation space can be eliminated.

In the above-mentioned vertical hollow fiber membrane module, during the filtration operation, the hole B of the protective cylinder and the scale discharge hole 8 are used as raw water supply holes, and the supply of raw water is balanced in the vertical direction of the module. For this purpose, as shown in FIG. 2, it is preferable that the hole B and the scale discharge hole 8 are provided vertically symmetrically.

With respect to the embodiment shown in FIG. 1 and FIG.
The communication pipe 3 is omitted, and the lower end of the hollow fiber membrane 2 is
It can also be closed by burying in b.

[0021]

[Effect of the Invention] The vertical hollow fiber membrane module of the present invention has the structure as described above. Even when the membrane is washed by the air-scrubbing method, the gas-liquid mixed flow is mainly sufficiently isolated from the lower surface of the upper partition wall. The gas-liquid mixed flow can flow out of the hole B at the position where the gas-liquid mixed flow has flowed sufficiently away from the lower surface of the upper resin partition wall. Since it can be avoided, damage to the film can be prevented. Further, since the small holes A are provided adjacent to the lower surface of the upper resin partition wall, gas accumulation in the protective cylinder can be eliminated, and deterioration of the film performance due to drying of the film can be avoided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is an explanatory sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Protective cylinder 2 Hollow fiber membrane bundle 4a Upper resin partition 41 Lower surface of upper resin partition A hole B hole

 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-62-237908 (JP, A) JP-A-3-38220 (JP, A) JP-A-2-191153 (JP, A)

Claims (2)

(57) [Scope of request for utility model registration] A hollow fiber membrane module in which a hollow fiber membrane bundle is accommodated in a vertical protection cylinder and an upper resin partition is formed at least at upper and lower ends of the protection cylinder to fix the hollow fiber membrane. Wherein a hole A is provided adjacent to the lower surface of the upper resin partition wall, and a hole B having a larger hole cross-sectional area than the hole A is provided slightly below the hole A. Membrane module
Le. 2. The diameter of the hole A is 1 to 10 times the outer diameter of the hollow fiber membrane.
The uppermost end of the hole B is 2 to 2 from the lower surface of the upper resin partition wall.
The vertical hollow fiber membrane module according to claim 1, which is located at a position of 3 cm.