JPH10339A - Hollow fiber membrane cartridge filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively perform air scrubbing of a regular cartridge filter without causing damages to hollow fiber membranes due to floating, cutting or bending of membranes by air bubbles. SOLUTION: The open ends of lots of hollow fiber membranes 1 which are folded like loops over a supporting member 2 are bundled and fixed with a cylindrical housing container 4 at one position. The membranes are housed to obtain 0 to 0.4% loosening rate R defined by formula (1) and 20 to 45% packing rate F defined by formula (2). (1) R=(L1 -L2 )/L2 , (2) F=Nd<2> /D<2> , wherein L1 is a distance from the fixed end of the hollow fiber membrane to the tip of the supporting body where the membranes are in a tension state and in contact with the supporting body, L2 is a distance from the fixed end of the hollow fiber membranes to the tip of the supporting member during use, and (d) and D are the outer diameter of the hollow fiber membrane and the inner diameter of the housing container of the membranes, respectively, and N is the twice as the number of housed hollow fiber membranes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for microfiltration, ultrafiltration, etc., in which a bubble passage is formed while supporting a hollow fiber membrane so that air scrubbing can be performed effectively without damaging the hollow fiber membrane. The present invention relates to a hollow fiber membrane type cartridge filter to be used.

[0002]

2. Description of the Related Art In the case of performing a total filtration using a hollow fiber membrane, a filtration area is advantageous. Therefore, an external pressure type filtration system for filtering from the outside to the inside of the hollow fiber membrane is often used.
Then, if the filtration is continued, the unfiltered substance accumulates on the surface of the hollow fiber membrane, and the filtration rate gradually decreases.

[0003] In order to remove accumulated substances from the membrane surface and restore the filtration ability again, air bubbles are flown outside the hollow fiber membrane to agitate the liquid in which the hollow fiber membrane is immersed (hereinafter referred to as air scrubbing). ) Method (for example,
1-1153104, JP-A-61-222509 and JP-A-61-254207), a method of using backwashing and air scrubbing together (JP-A-60-1900)
No. 2, JP-A-62-4408) and the like. These are all excellent methods, which efficiently restore the filtration capacity and contribute to greatly extending the filtration life.

[0004] A module in which the hollow fiber membrane is focused and fixed at both ends and a module in which the hollow fiber membrane is folded in a loop at the center and focused and fixed at one end, which are suitable for these methods, have also been devised. In the module fixed at one end, the loop portion is supported so that the hollow fiber membrane is not disturbed during the air scrubbing (for example, Japanese Patent Application Laid-Open No. 60-255114), and the supporting member also has a bubble passage. (For example, Japanese Patent Laid-Open No. 60-206414).

[0005] On the other hand, backwashing and air scrubbing cannot be performed, but as a module for filtering a relatively small amount, as is well known to those skilled in the art, a flat membrane is folded into a pleated shape for a long time, and the outer diameter is reduced. A large number of so-called economical fixed-type cartridge filters housed in a structure of a common design regardless of the manufacturer have been used.

A module incorporating a hollow fiber membrane which is compatible with these fixed type cartridge filters has also been devised by the same person as the present inventor (JP-A-2-227).
No. 125, JP-A-6-182161, etc.)
However, these are not structures suitable for air scrubbing.

[0007]

Therefore, if a hollow fiber membrane type module which is desirably a fixed type cartridge filter and which is suitable for air scrubbing can be devised, it will have both advantages. Here, in order to be able to perform air scrubbing effectively, it is necessary that air bubbles hit as many hollow fiber membranes as possible and the hollow fiber membranes fluctuate.

In the above-described cartridge filter in which a large number of hollow fiber membranes folded in a loop shape are converged and fixed together with the storage container in one place, in order to widen the air bubble path and effectively perform air scrubbing, the hollow fiber is merely used. If the number of membranes stored is reduced, the hollow fiber membrane soared by air bubbles may be cut or bent and damaged.
Therefore, it is necessary to support the loop portion in order to prevent the hollow fiber membrane from rising. However, it is difficult to say that the module having the support member has a structure that can be effectively used for a cartridge filter.

As described in JP-A-60-206414, when a very large number of hollow fiber membranes are used, the passage of bubbles in the support member is effective, but the number of hollow fiber membranes to be filled is relatively large. In the case of a cartridge filter having a small number of filters, not only this passage is unnecessary but also a drawback of reducing the number of filled hollow fiber membranes. Also, JP-A-60-25
When the hollow fiber membrane is excessively slackened as described in Japanese Patent No. 5114, the hollow fiber membrane meanders in the container in the case of a cartridge filter, and the free movement of the hollow fiber membrane is hindered. The effect is poor.

Accordingly, an object of the present invention is to provide a hollow fiber membrane type cartridge filter which solves these problems and enables effective air scrubbing.

[0011]

In order for the hollow fiber membrane type cartridge filter to be able to perform air scrubbing effectively, as described above, the hollow fiber membrane does not fly up due to air bubbles, and the air bubbles hit as many hollow fiber membranes as possible. In addition, the hollow fiber membrane must move freely. For that purpose, the hollow fiber membrane is supported by the loop part,
It is necessary to ensure that the air bubbles do not meander in the storage container, and that the air bubbles freely swing.

That is, the present invention relates to a hollow fiber membrane type cartridge filter in which the open ends of a large number of hollow fiber membranes which are folded back in a loop shape beyond a support member are fixed together at one place together with the cylindrical storage container. A hollow fiber membrane type cartridge having a slack rate R defined by the following formula of 0 to 0.4% and a filling factor F defined by the formula of 20 to 45%. It is to provide a filter. R = (L ₁ −L ₂ ) / L ₂ F = Nd ² / D ² where L ₁ is the distance from the fixed end of the hollow fiber membrane in contact with the support member in the tensioned state to the top of the support member,
L ₂ represents the distance from the fixed end of the hollow fiber membrane in use until the top portion of the support member, d, the outer diameter of D and each hollow fiber membrane, the inner diameter of the container of the hollow fiber membrane, N is the loop 2 shows twice the number of folded hollow fiber membranes.

When the storage container for the hollow fiber membrane is a perforated cylinder, the storage container for a fixed type cartridge filter can be diverted. It is more preferable that the support member is made of a stretchable material.

[0014]

1 and 2 show two embodiments of the hollow fiber membrane type module according to the present invention in which the loop portion has a different supporting form. (A) of each figure is a partial cross-sectional view in the longitudinal direction of the hollow fiber membrane 1 including the support member 2, and (b) is a partial cross-sectional view perpendicular to the longitudinal direction of the hollow fiber membrane 1. All figures show a state in which the hollow fiber membrane 1 is pushed up by air bubbles and is in contact with the support member 2. The hollow fiber membrane 1a in contact with the support member 2 is shown in black. still,
The support member 2 shown in FIG. 1 has a circular cross section and a substantially U-shaped overall shape. The support member 2 shown in FIG.
The cross section is circular and the overall shape is substantially U-shaped.

FIG. 3 is a diagram for defining the slack rate R. The support member 2 and the hollow fiber membrane 1 that can contact the support member 2 are shown in FIG.
a, the focusing fixing member 3 is shown. L ₁ is the distance from the fixed end of the hollow fiber membrane in tension indicated by the chain line to the top of the support member, the distance L ₂ from the fixed end of the hollow fiber membrane in use until the top portion of the support member Show. Therefore, even if the support forms are different as in FIG. 1 or FIG. 2, the slack rate R [= (L ₁ −L ₂ ) / L ₂ ] can be defined in common. When the supporting member 2 is made of a rigid material, the slack rate R needs to be in the range of 0.04 to 0.4%.

When the slack ratio R is less than 0.04%, free fluctuation of the hollow fiber membrane is hindered, and the air scrubbing effect is reduced. On the other hand, when the slack rate R exceeds 0.4%, the hollow fiber membrane lifted by air bubbles during air scrubbing comes into contact with the storage container a plurality of times and is in a meandering state. The scrubbing effect decreases.

As the support member 2, it is also possible to use a material having elasticity so that the bundle of the hollow fiber membranes 1 can be lifted by air bubbles during air scrubbing. In this case, the slack rate R can be set to zero. However, the elastic modulus is selected so that the hollow fiber membrane stays in tension during air scrubbing, or has a slack state in the same range as when using a substantially rigid support member so that it does not meander due to excessive slack. There is a need to. Compared to a rigid support member, the arrangement of the hollow fiber membranes is less disturbed when supporting a large number of hollow fiber membranes, and in such a case, a stretchable material is preferable.

The number of hollow fiber membranes to be filled in the storage container 4 is as follows.
The filling rate F [= Nd ² / D ² ] defined by the equation is 20 to 4
Must be in the range of 5%. If the filling rate F is less than 20%, the effect of air scrubbing is not impaired, but the effective area becomes poor and the filtration rate decreases. Conversely, the filling rate F
Is more than 45%, the passage of the air bubbles becomes narrow, the hollow fiber membranes hit by the air bubbles are reduced, and the air scrubbing effect is lowered. In addition, when a perforated cylinder as shown in FIG. Air bubbles escape from these holes to the outside of the storage container, and the air scrubbing effect is further reduced.

If the hollow fiber membrane has a microfiltration or ultrafiltration function for filtering from the outer surface to the inner surface of the hollow fiber membrane, there is no particular limitation on the hollow fiber membrane used in the present invention, but air scrubbing is effective. Need to be flexible, and thick ones are not preferred, but thin and brittle ones are not preferred. Therefore, it is desirable that the outer diameter is 300 to 1000 μm and the thickness is 30 to 300 μm. Various types of such hollow fiber membranes are already known, for example, hollow fibers made of cellulose, polyacrylonitrile, polysulfone, polyolefin, polyvinyl alcohol, fluorinated polymers such as polyvinylidene fluoride and polytetrafluoroethylene, and the like. It is possible to use a thread membrane. Among these, polysulfone-based hollow fiber membranes can be adjusted in a wide range, such as adjustment of pore diameter, outer diameter, and wall thickness.
It is particularly preferable because the strength is relatively excellent.

FIG. 4 shows an example of a so-called fixed type hollow fiber membrane type cartridge filter M of the present invention, which is compatible with the above-mentioned conventional pleated type cartridge filter. The hollow fiber membrane 1 having a hole 10 has an outer diameter of about 7 cm and a length of about 20 to 1
It is stored in a cylindrical storage container 4 of 00 cm, and the opening end is fixed together with the storage container 4 at one place by the convergence fixing material 3. A bottom 5 having a hole 7 serving as an air inlet for air scrubbing is connected to one end of the storage container 4 (this bottom 5 is not particularly necessary, and may be simply an open end). , The other end of the filtrate 8
Is connected. The cartridge filter M is used by being mounted on a housing (not shown) via an O-ring 9. Therefore, this hollow fiber membrane type cartridge filter can be used not only in the same manner as the conventional one, but also while recovering the filtration ability by backwashing or air scraping.

The convergence fixing material 3 is usually made of epoxy resin or urethane resin. In addition, synthetic polymers such as polycarbonate, ABS, polysulfone, polyvinyl chloride, and polypropylene are used for the storage container 4, the bottom 5, and the header 6. The storage container 4, the bottom 5 and the header 6 are connected by an adhesive, ultrasonic welding, or heat welding.

When air scrubbing a hollow fiber membrane type cartridge filter having a reduced filtration capacity, air bubbles are sent from the holes 7 in the bottom 5. In the hollow fiber membrane type cartridge filter of the present invention, even if the storage container 4 has a large number of holes 10 as shown in the drawing, most of the bubbles escape from the middle hole while swinging the entire hollow fiber membrane. When it reaches the uppermost part and squirts from the hole near the uppermost part, the deposit attached to the film surface is difficult to peel off. It is also possible to use one that is partially covered with a heat-shrinkable tube 11 so as to close the hole 10 in a portion close to 5, or one that is non-porous in the middle and has an air bubble outlet only near the upper part. The air bubbles after the air scrubbing are discharged to the outside from the air bubble outlet of the housing (not shown).

[0023]

EXAMPLES The following examples will explain the hollow fiber membrane type cartridge filter of the present invention more specifically, but these examples do not limit the present invention.

(Embodiment 1) A slit-like hole having a total length of about 70 cm, inner and outer diameters of about 62 and 70 mm, and having a circumferential length of about 15 mm and a major axis length of 5 mm over almost the entire surface. 1
In a perforated polypropylene cylinder (storage container 4) in which 0 are arranged in eight rows in the circumferential direction, an outer diameter is 600 μm and an inner diameter is 300 μm.
2,000 pieces of polysulfone hollow fiber membranes 1 having a pore size of about 0.1 μm and a filling rate F of about 37% were filled.
As about 65cm to L ₁ of, and supported by the silicon rubber having a diameter of about 3mm in the slack rate R substantially zero so that the loop portion in the shape of FIG. 1 (the supporting member 2). After the opening end of the hollow fiber membrane is fixed and fixed with urethane resin together with the perforated cylinder at one place (the fixing fixing material 3), the header 6 and the bottom 5 made of polypropylene are heat-welded to prepare a cartridge filter shown in FIG. did.

Approximately 1/3 from the bottom of the perforated cylinder (storage container 4)
After covering the length with a heat-shrinkable shoe, this cartridge filter is attached via an O-ring to a housing made of a transparent pipe with an inner diameter of about 75 mm so that the hollow fiber membrane can be observed. Then, the bottom of the cartridge was fixed to the housing so that the cartridge would not come off during backwashing.

With this cartridge filter, a wastewater containing about 5 ppm of activated carbon powder is supplied at a rate of about 500 l / h.
After filtering for 1 minute, the solution was backwashed with about 3 liters of the filtrate, and air scrubbing was performed by blowing air bubbles from the bottom of the cartridge filter at a flow rate of 20 liters / minute for 3 minutes. By repeating this operation, the movement of the hollow fiber membrane, the movement of the air bubbles, the detachment state of the activated carbon adhering to the membrane surface, and the change in the filtration pressure were measured.

At the time of air scrubbing, the entire hollow fiber membrane was lifted by about 2 mm, and a state was observed in which the entire hollow fiber membrane swayed without meandering as bubbles rose. In addition, most of the bubbles that had entered the perforated cylinder reached the uppermost part without protruding from the hole in the middle. Almost the entire hollow fiber membrane whose surface became black due to the adhesion of the activated carbon, except for the loop portion and the vicinity of the convergence fixing portion, was nearly white due to the air scraping. The filtration pressure gradually increased as shown in FIG. 5, and reached 100 KPa after 260 hours of the total filtration time.

Example 2 L _{1 in} tension (650 m)
At a position about 2 mm shorter than m), the loop part is 6 m thick.
The cartridge filter prepared in the same manner as in Example 1 except that the filter was supported by the rigid round bar-shaped support member 2 made of polypropylene and having a slack rate R of 0.3% as shown in FIG. It evaluated similarly. The obtained results were almost the same as in Example 1.

(Comparative Example 1) A cartridge filter was prepared and evaluated in the same manner as in Example 2 except that the slack rate R was set to 0.5%. The hollow fiber membrane meandered during air scrubbing, and free fluctuation was observed. Was obstructed. Further, in a portion meandering and contacting the inner surface of the storage container, it was observed that air bubbles escaped to the outside of the storage container, and a considerable amount of black stains of activated carbon remained. Further, the filtration pressure reached 100 KPa after 230 hours, and the filtration life was shorter by about 12% than that of Example 1 or Example 2.

Comparative Example 2 A cartridge filter was prepared and evaluated in the same manner as in Example 1 except that 2500 hollow fiber membranes were used so that the filling factor F was about 47%. As a result, it was observed that air bubbles did not enter the inside of the hollow fiber membrane bundle during air scrubbing, and only the hollow fiber membrane near the surface of the bundle swayed. It was also observed that a large amount of air bubbles escaped from the hole in the middle of the storage container. Also, the filtration pressure reaches 100 KPa after 200 hours,
The filtration life was shortened by about 23% as compared with that of Example 1 or Example 2.

[0031]

The hollow fiber membrane type cartridge filter of the present invention can be used in the same manner as the conventional cartridge filter, especially in the case of a fixed type design. It is also possible to effectively restore the filtration capacity by air scrubbing, and it is economical and has a wide range of applications as a filter for small- to medium-scale filtration.

[Brief description of the drawings]

FIG. 1 shows a state in which a loop portion of a hollow fiber membrane stored in a storage container is supported by a substantially U-shaped support member, where (a) is a partial longitudinal sectional view and (b) is a transverse sectional view.

FIGS. 2A and 2B show a state in which a loop portion of a hollow fiber membrane stored in a storage container is supported by a substantially U-shaped support member, wherein FIG. 2A is a partial longitudinal sectional view, and FIG.

FIG. 3 is an explanatory diagram for defining a slack rate R.

FIG. 4 is a half sectional view showing a fixed type hollow fiber membrane type cartridge filter which is an example of the present invention.

FIG. 5 is a graph showing the results of Example 1 and showing the relationship between the total filtration time and the filtration pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow fiber membrane 1a Hollow fiber membrane which can contact a support member 2 Support member 3 Focusing fixing material 4 Storage container of hollow fiber membrane 5 Bottom 6 Header 7 Bottom hole 8 Filtrate outlet 9 O ring 10 Hole 11 Heat shrinkability tube

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[Procedure amendment]

[Submission date] January 16, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

At the time of air scrubbing, the entire hollow fiber membrane was lifted by about 1 mm, and a state was observed in which the entire hollow fiber membrane swayed without meandering as bubbles rose. simultaneous
In the loop, a small roll (up and down direction in FIG. 1B)
Was also observed. In addition, most of the bubbles that had entered the perforated cylinder reached the uppermost part without protruding from the hole in the middle. Almost the entire hollow fiber membrane whose surface became black due to the adhesion of the activated carbon, except for the loop portion and the vicinity of the convergence fixing portion, was nearly white due to the air scraping. The filtration pressure gradually increased as shown in FIG. 5, and reached 100 KPa after 260 hours of the total filtration time.

Claims (3)

[Claims] 1. A hollow fiber membrane type cartridge filter in which the open ends of a large number of hollow fiber membranes folded in a loop over a support member are fixed at one place together with the cylindrical storage container thereof by the following formula: A hollow fiber membrane-type cartridge filter, wherein the defined slack rate R of the hollow fiber membrane is 0 to 0.4% and the filling rate F defined by the formula is 20 to 45%. R = (L ₁ −L ₂ ) / L ₂ F = Nd ² / D ² where L ₁ is the distance from the fixed end of the hollow fiber membrane in contact with the support member in the tensioned state to the top of the support member,
L ₂ represents the distance from the fixed end of the hollow fiber membrane in use until the top portion of the support member, d, the outer diameter of D and each hollow fiber membrane, the inner diameter of the container of the hollow fiber membrane, N is the loop 2 shows twice the number of folded hollow fiber membranes. 2. The hollow fiber membrane type cartridge filter according to claim 1, wherein the storage container for the hollow fiber membrane is a perforated cylinder. 3. The hollow fiber membrane type cartridge filter according to claim 1, wherein the support member is made of an elastic material.