JPH1028845A - Housing of hollow fiber membrane cartridge filter and backwashing thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a housing capable of backwashing two or more mounted fixed form type hollow fiber membrane cartridge filters by high pressure air by utilizing a conventional housing within the range of possibility and to provide a backwashlng method therefor. SOLUTION: In a housing having at least an inlet 7 of a liquid to be treated, a filtrate outlet 6, a vent 11 and a drain outlet 9 and mounting two or more fixed form type hollow fiber membrane cartridge filters 5, the cartridge filter 5 on the side of the filterate outlet 6 is mounted on a partition plate 4 demarcating the liquid to be treated and a filtrate and a fixing plate 2 is arranged on the opposite side thereof and these plates are fixed to the cartridge filters by one or more of fastening jig (bolt) so as to withstand pressure backwashing hollow fiber membranes by air of which the pressure is equal to or more than the bubble point of the hollow fiber membranes in the direction reverse to a filtering direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing of a hollow fiber membrane cartridge filter for microfiltration. More specifically, the present invention relates to a fixed type hollow fiber membrane cartridge filter housing capable of backwashing a hollow fiber membrane with high-pressure air.

[0002]

2. Description of the Related Art Conventionally, a so-called pleated type cartridge filter in which a space between double perforated double cylinders is filled with a film-like membrane having a large number of folds has been widely used as a cartridge filter for filtering a fluid. . Although the main pleated cartridge filters are not specified by official standards such as JIS, the design such as the mounting dimensions to the housing, the overall length, and the basic dimensions such as thickness are unified so that the products of each company can be interchanged. ing. The standard type in the present invention means that these designs are common to the pleated type cartridge filter.

[0003] A fixed-type hollow fiber membrane cartridge filter that is compatible with a pleated cartridge filter has also been developed. For example, in Japanese Patent Application Laid-Open No. 62-74408, a non-perforated inner cylinder is used in place of a perforated inner cylinder of a pleated cartridge filter, and a hollow fiber membrane filled in a space between the perforated outer cylinder at both ends is used. Focused and fixed is described. In Japanese Patent Application Laid-Open No. Sho 64-30605, only a pleated perforated outer cylinder is used, and a hollow fiber membrane is filled therein, one end is sealed with a potting material, and the other end is opened so as to be open. The fixed one is shown. Also, Japanese Unexamined Patent Publication No.
No. 161 describes that a hollow fiber membrane folded in a loop shape is bundled and fixed together with a storage container at one place. Further, JP-A-8-117568 discloses a filtration device in which two or more housings each having two or more of these fixed type hollow fiber membrane cartridge filters are connected in series.

[0004]

However, these are mainly focused on the filtration function, and the hollow fiber membrane cartridge filter is detached from the housing by the backwash pressure. The backwashing of the membrane is not actively intended, and the means for doing so is not very specific. In particular, in the case where two or more hollow fiber membrane cartridge filters are mounted in one housing, backwashing can be performed by using the housing described in FIG. 5 of the above-mentioned Japanese Patent Application Laid-Open No. 8-117568. Although possible, it has a special structure in which both ends of the filter are fixed by two housings, and lacks versatility.

Accordingly, an object of the present invention is to provide a housing which enables backwashing of a fixed type hollow fiber membrane cartridge filter mounted with two or more conventional housings as much as possible using high pressure air. The purpose is to provide a backwashing method.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple and reliable fixing of a plurality of hollow fiber membrane cartridge filters using a conventional housing so as not to be detached from the housing during backwashing with high-pressure air. Will be resolved if possible.

That is, the present invention provides "at least an inlet for a liquid to be treated, an outlet for a filtrate, a vent and a drain outlet,
In a housing for mounting two or more fixed type hollow fiber membrane cartridge filters, the filtrate outlet side of the cartridge filter is mounted on a partition plate for partitioning the liquid to be treated and the filtrate, and a fixing plate is provided on the opposite side. These plates are arranged by one or more clamping jigs so as to withstand the pressure of backwashing the hollow fiber membrane with air having a pressure not lower than the bubble point of the hollow fiber membrane from the direction opposite to the filtration direction. A hollow fiber membrane cartridge filter housing characterized by being capable of fixing a cartridge filter.

According to the present invention, by adding an appropriate fixing plate and a jig for tightening the fixing plate, the conventional housing can be used as it is as a backwashing function using high-pressure air, which is extremely economical. is there.

[0009]

FIG. 1 is a schematic partial sectional view showing an example of a housing according to the present invention, in which seven hollow fiber membrane cartridge filters are mounted. 2 and 3 are schematic cross-sectional views taken along the lines AA and BB of FIG. 1, respectively, wherein 1 is a housing, 2 is a fixing plate, 3 is a fixing bolt, 4 is a partition plate, and 5 is a hollow fiber membrane. Each shows a cartridge filter.

Inside the housing 1, a hollow fiber membrane cartridge filter 5 is mounted on a partition plate 4 for separating a liquid to be treated and a filtrate through an O-ring. Three fixing bolts 3 as a jig for fastening the fixing plate 2 disposed at the other end
When the cartridge filter 5 is backwashed with air having a pressure of 1 MPa or less, the cartridge filter 5
It is fixed so that it does not come off from the mounting part.

At the time of filtration, the liquid to be treated enters the housing 1 from the inlet 7, and the liquid filtered from the outside to the inside of the hollow fiber membrane of the cartridge filter 5 is taken out from the filtrate outlet 6.

When the cartridge filter 5 whose filtration pressure has been increased is backwashed with air of 1 MPa or less, a small amount of a liquid to be treated, a filtrate or an appropriate cleaning liquid is sent from the inlet 7 of the liquid to be treated into the housing 1 while a high pressure is applied. Air flows from the inlet 8 to the inside of the hollow fiber membrane of the cartridge filter 5 from the inside to the outside to remove accumulated substances attached to the outer surface of the hollow fiber membrane. The liquid containing the separated accumulated substances is pushed out from the drain outlet 9 together with the liquid to be treated, the filtrate, or the cleaning liquid other than these, and the air that has come out of the cartridge filter 5. As these outlets, it is also possible to use vents 11 which are usually used for venting air in the housing. The hole 10 formed in the fixing plate 2 shown in FIG. 2 also serves as a passage for the liquid containing the separated accumulated matter.

In order for air to push out the liquid in the thick part of the hollow fiber membrane and flow from the inside to the outside of the hollow fiber membrane, the pressure must be at least equal to or higher than the bubble point of the hollow fiber membrane. When the liquid in the thick part of the membrane is extruded, the air pressure drops sharply because the resistance to the flow of air drops sharply. Therefore, the substantial backwashing is performed before the pressure of the air suddenly decreases, and thus is completed in a short time.

The fixing plate is also used in the housing of the conventional pleated cartridge filter, but its purpose is not to withstand the pressure during backwashing but to prevent the cartridge filter from wobbling. Therefore,
Sometimes it cannot withstand backwashing with high-pressure air that applies a force of several hundred kg.

It is known that the bubble point of a hollow fiber membrane is inversely proportional to its pore diameter and almost proportional to the surface tension of the impregnating liquid. For example, when the liquid existing in the thick part of the hollow fiber membrane is water, The bubble point corresponding to a pore diameter of 0.1 μm is approximately 900 kPa. However, in the case of a liquid having a small surface tension, such as an aqueous alcohol solution or water containing a surfactant, the bubble point is smaller than that of water. In consideration of such a liquid, the pore size of the hollow fiber membrane to which the present invention is applied is about 0.05 μm or more.

If the maximum backwash pressure of air exceeds 1 MPa, not only a compressor for generating high-pressure air but also a special pressure-resistant structure is required for the housing and the piping material. Is not necessarily more economical than Therefore, the maximum air pressure for backwashing is 1
MPa or less.

FIG. 4 shows an example of a fixed type hollow fiber membrane cartridge filter 5 which can be used in the present invention. The hollow fiber membrane 20 folded in a loop shape is fixed together with a cylindrical storage container 21 having a large number of holes 26 at one place in a convergence fixing section 22 usually with an epoxy resin or urethane resin. The outer diameter of the storage container 21 is about 70 mm, and the total length of the cartridge filter is about 25, 50 or 75c.
m. The partition 2 (see FIG. 1) has a header 2
4 is mounted via an O-ring 23. Although a design in which a gasket is used instead of an O-ring for sealing is also known, an O-ring type is preferable in terms of pressure resistance and reliability.
Further, a method of sealing the hollow fiber membrane with a potting material instead of folding the hollow fiber membrane into a loop shape is also known, but this is not preferable because free movement of the hollow fiber membrane is hindered during backwashing.

At the other end of the storage container 21, there is a bottom 28 having a hole 27 (not particularly required, and may be left open), and the fixing plate 2 applied to the bottom 28 is fixed to a fixing bolt 3 (FIG. 1). 3), the cartridge filter 5 is fixed by tightening the fixing plate 2 and the partition plate 4.

The hollow fiber membrane is not particularly limited as long as it can withstand the pressure at the time of backwashing, and many hollow fiber membranes such as polysulfone, polyolefin, polyacrylonitrile, polyvinylidene fluoride, and cellulose are already known. Have been.

The liquid to be treated is filtered from the outside of the hollow fiber membrane 20 to the inside thereof, and collects at the filtrate outlet 6 of the housing 1 through the filtrate passage 25.

As described above, the conventional housing 1
The hollow fiber membrane is backwashed by fixing the hollow fiber membrane cartridge filter 5 with the fixing plate 2 and the fixing bolt 3 so that the hollow fiber membrane cartridge filter 5 is not detached by the pressure at the time of backwashing,
It has become possible to greatly extend its life.

[0022]

Next, the present invention will be described more specifically with reference to examples, but these examples do not limit the present invention.

(Example 1) Inner diameter: about 62 mm, outer diameter: 70 m
m, folded into a loop in a storage container 21 made of a perforated polypropylene cylinder having a length of about 71 cm.
After inserting 1500 polysulfone hollow fiber membranes having an outer diameter of 500 or 800 μm and a pore diameter of about 0.45 μm, and fixing the opening end in one place with a perforated cylinder with urethane resin, a polypropylene header 24 and a bottom 28 was thermally welded to a perforated cylinder to prepare a hollow fiber membrane cartridge filter having a total length of about 75 cm.

The above bubble point of the hollow fiber membrane is about 200% when the impregnating liquid is a 30% by volume aqueous ethanol solution.
kPa and about 380 kPa for water.

Seven cartridge filters were mounted in a commercially available stainless steel housing having an inner diameter of about 300 mm in a straight pipe portion, and a diameter of about 25 mm shown in FIGS.
It was fixed with a stainless steel fixing plate 2 having a thickness of 0 mm and a thickness of 10 mm and three bolts having a thickness of 15 mm.

The average particle size of the filtration device is 0.5 μm.
Of a 100 ppm aqueous dispersion of colloidal silica
The mixture was filtered at a flow rate of L (L represents liter; the same applies hereinafter) for 1 hour. During this time, the filtration pressure increased from 3 kPa to 10 kPa. No colloidal silica was found in the filtrate.

Next, the vent 11 was opened and the filtrate side was pressurized with high-pressure air of 400 kPa while feeding the colloidal silica dispersion at a flow rate of 10 L / min from the inlet 7 of the liquid to be treated. After about 20 seconds, the air pressure suddenly rises to about 20 kPa
Then, the cloudy liquid containing air bubbles rapidly flowed out of the vent 11. After allowing the mixture to stand for 1 minute, the supply of the colloidal silica dispersion and the supply of air were stopped. Subsequently, the drain outlet 9 was opened to discharge the cloudy liquid in the housing. The filtration operation was repeated again, but the filtration pressure showed almost the same change as the first time.

(Example 2) Inner and outer diameters of 500 and 800 μm
A hollow fiber membrane cartridge filter was prepared in the same manner as in Example 1 except that a hollow fiber membrane having a pore size of about 0.2 μm was used. The bubble point of this hollow fiber membrane was about 750 kPa when the impregnating liquid was water.

Seven cartridge filters were mounted on the housing used in Example 1 and had an average particle size of about 0.3.
A 2 μm colloidal silica 100 ppm aqueous dispersion was filtered at a flow rate of 70 L / min for 1 hour. During this time, the filtration pressure increased from 7 kPa to 23 kPa. No colloidal silica was found in the filtrate.

Next, after backwashing was performed in the same manner as in Example 1 except that high-pressure air of 800 kPa was used, filtration was repeated. However, the filtration pressure showed almost the same change as the first time.

(Comparative Example 1) A filtration device assembled in the same manner as in Example 2 was installed upside down, and a colloidal silica dispersion was filtered in the same manner as in Example 2.

Next, the drain outlet 9 is opened, and while the filtrate side is kept pressurized with air of 100 kPa, the vent 1 is opened.
1 to 100 NL of air was sent per minute to perform air scrubbing for 3 minutes, and then the vent was opened to discharge the cloudy liquid in the housing.

When the filtration was repeated again, the initial filtration pressure was 10 kPa, and increased to 28 kPa after about one hour. This example shows that backwashing with high-pressure air has a higher recoverability of filtration capacity than washing with air scrubbing.

[0034]

According to the present invention, the hollow fiber membrane cartridge filter is fixed to the fixing plate and the clamping jig so as not to be detached while using the conventional housing, so that the hollow fiber membrane can be backwashed with high-pressure air. It has become possible, and its life can be greatly extended.

[Brief description of the drawings]

FIG. 1 shows a standard hollow fiber membrane cartridge filter 7
It is a half sectional view showing an example of the housing of the present invention which was fully installed.

FIG. 2 is a simplified sectional view taken along line AA of FIG.

FIG. 3 is a simplified sectional view taken along line BB of FIG. 1;

FIG. 4 is a half sectional view of a fixed type hollow fiber membrane cartridge filter used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Fixing plate 3 Fixing bolt (clamping jig) 4 Partition plate 5 Hollow fiber membrane cartridge filter 8 Filtrate outlet 7 Liquid to be treated inlet 8 High pressure air inlet 9 Drain outlet 10 Hole 11 Vent 20 Hollow fiber membrane 21 Storage container 22 Focusing fixing part 23 O-ring 24 Header 25 Filtrate passage 26 Hole 27 Hole 28 Bottom

Claims (6)

[Claims] 1. A housing for mounting at least two fixed-form hollow fiber membrane cartridge filters having at least an inlet for a liquid to be treated, an outlet for a filtrate, a vent and a drain outlet. The outlet side is attached to a partition plate that separates the liquid to be treated and the filtrate, and a fixing plate is arranged on the opposite side, and these plates are tightened by one or more clamping jigs from the direction opposite to the filtration direction. A housing for a hollow fiber membrane cartridge filter, wherein the cartridge filter can be fixed so as to withstand a pressure for backwashing the hollow fiber membrane with air having a pressure higher than a bubble point of the fiber membrane. 2. The housing for a hollow fiber membrane cartridge filter according to claim 1, wherein the hollow fiber membrane cartridge filter of a fixed type is one in which the opening of the hollow fiber membrane is focused and fixed together with its storage container at one place. 3. The hollow fiber membrane cartridge filter housing according to claim 1, wherein the mounting portion of the fixed type hollow fiber membrane filter to the partition plate has an O-ring seal structure. 4. The hollow fiber membrane cartridge filter housing according to claim 1, wherein the maximum backwash pressure of air is 1 MPa or less. 5. The hollow fiber membrane cartridge filter housing according to claim 1, wherein the fixing plate has a hole communicating with the hollow fiber membrane storage container. 6. The hollow fiber membrane cartridge filter using a housing according to claim 1, wherein the liquid to be treated, the filtrate, or a cleaning liquid other than these is backwashed with air while being introduced from an inlet of the liquid to be treated. Backwashing method.