JPH09220446A - External pressure type hollow yarn membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the dischargeability of waste physically washing water and to hardly cause the damage of hollow yarn membranes near the fixed interface of the hollow yarn membranes by installing high molecular material layers of rubber-like elasticity for covering the perimeters of the membranes near the end surfaces inside adhesive fixed parts of resin partitions at both ends and the hollow yarn membranes. SOLUTION: A module has feed ports 7 for raw water consisting of through holes made in one resin partition 4 itself, a straightening cylinder 8 arranged around the bundle end part on the opposite side of the raw water feed ports 7, and high molecular material layers 5 of rubber-like elasticity for covering the membrane peripheral surface around the inner end surfaces of the adhesive- fixed parts between the resin partitions 4 at both ends and hollow yarn membranes 2. In this way, by a membrane shake on crossflow filtration and on aeration flushing washing, shear stress generated, concentrated to around the adhesive interfaces between the resin partitions 4 and the hollow yarn membrane 2 is dispersed and relaxed, and a bend angle near the adhesive interface of the hollow yarn membrane 2 due to its being pulled in on discharge of backwashing water is relaxed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hollow fiber membrane module used in various fields, and more particularly to an external pressure type hollow fiber membrane module used in the field of water treatment.

[0002]

2. Description of the Related Art Since a hollow fiber membrane module can secure a large membrane area per unit volume, it can be used in many fluid treatment fields such as desalination of canned water and seawater by reverse osmosis membrane, and ultrapure water. Primary pure water treatment, removal of low molecular weight organic substances such as pesticides and polysaccharides by nanofilter, concentration and desalting of enzyme by ultrafiltration membrane, production of water for injection, collection of electrodeposition paint,
Final filtration of ultrapure water, wastewater treatment, turbidity of river water / lake water / underflow water, chemical purification by microfiltration membrane, sterilization, turbidity, oxygen separation by gas separation membrane, nitrogen separation, hydrogen separation, It is used for carbon dioxide separation.

Hollow fiber membrane modules typically have a length of 200
˜3000 mm, outer diameter 0.1 to 5 mm, and several hundred to tens of thousands of hollow fiber membranes are bundled and housed in a module case. Both ends are adhesively fixed and then the ends are cut to remove the hollow fiber membranes. It is manufactured by opening the hollow part. Furthermore, an external pressure type hollow fiber membrane module in which a plurality of raw water supply ports are provided in a hollow fiber membrane bundle in parallel with the hollow fiber membrane is known as a membrane module having excellent discharge properties of suspended matter. ing. In this membrane module having only the raw water supply port opened on the end face, an inlet pipe for raw water supply is buried at the raw water supply side end of the hollow fiber membrane bundle, and resin is injected into the hollow portion of the hollow fiber membrane. After adhesively fixing in this manner, the bundle ends can be cut to produce the same.

In order to obtain the filtration stability of raw water containing suspended solids, the suspended solids in the membrane module are usually subjected to filtration methods such as cross-flow filtration, backwash, aeration flushing and the like, and physical washing. To prevent the accumulation of. In order to discharge the suspended solids accumulated in the module more efficiently, when the module is installed vertically, cross-flow filtration supplies raw water containing suspended solids from the raw water supply port at the bottom. The method of discharging concentrated water from the concentrated water outlet provided on the upper side surface, and the cleaning by aeration flushing are performed by supplying raw water mixed with gas such as compressed air from the raw water supply port at the bottom, and mixing air and water. By shaking the membrane with the method of discharging the suspended solids from the concentrated water outlet provided on the upper side surface, in the case of backwashing, pressurization with filtered water is performed from the upper filtered water outlet,
The method of discharging the suspended solids adhering to the outer surface of the membrane from the raw water supply port at the bottom of the module or the concentrated water discharge port at the upper side of the module along with the backwash drainage and both sides is Is excellent.

However, the cross-flow filtration and the aeration flushing cleaning are performed in the vicinity of both end portions of the hollow fiber membrane so as to swing vertically to the fiber direction of the hollow fiber membrane, and the backwash discharge water is discharged through the raw water supply port or the concentrated water discharge. When the hollow fiber membrane is drawn in by the liquid flow when it is discharged from the nozzle, the hollow fiber membrane may be damaged near the adhesive fixing interface.

As means for preventing damage at the hollow fiber membrane adhesive fixing interface due to shearing force acting perpendicularly to the fiber direction of the hollow fiber membrane, (1) a rectifying tube is installed near the membrane adhesive fixing interface. A method, (2) a method of providing a polymer material layer having rubber-like elasticity on the adhesive fixing interface of the membrane, (3) a method of winding a net made of a polymer material around the hollow fiber membrane bundle, and (4) a hollow fiber membrane There is known a method of providing a nozzle for discharging concentrated water or supplying raw water near the central portion in the length direction.

However, in the external pressure type hollow fiber membrane module in which a plurality of raw water supply ports are provided in the hollow fiber membrane bundle in parallel with the hollow fiber membrane, the method (1) is for discharging concentrated water. The effect of improving the hollow fiber membrane being pulled in is great, but it cannot be the effect of improving the sway of the hollow fiber membrane.
On the contrary, the method (2) is excellent in the improvement effect on the swing of the hollow fiber membrane, but the improvement effect on the pulling in of the hollow fiber membrane due to the discharge of the concentrated water is not so large. Also (3)
The methods of (4) and (4) have the effect of improving the pulling of the hollow fiber membrane and the swaying of the hollow fiber membrane due to the discharge of concentrated water, but accelerate the accumulation of suspended substances in the hollow fiber membrane bundle, and Requires advanced pretreatment for use.

[0008]

DISCLOSURE OF THE INVENTION According to the present invention, the discharge of physical cleaning wastewater is excellent, the accumulation of suspended substances is small, and the hollow fiber membrane is less likely to be damaged in the vicinity of the adhesive fixing interface of the hollow fiber membrane. An object is to provide an external pressure type hollow fiber membrane module.

[0009]

SUMMARY OF THE INVENTION The present invention provides an external pressure type hollow fiber membrane module in which both ends of a bundle of a large number of hollow fiber membranes are adhesively fixed to a case by resin partition walls, and one resin partition wall itself is opened. A raw water supply port consisting of a through hole, a rectifying cylinder arranged around the bundle end opposite to the raw water supply port, a resin partition wall at both ends and a hollow fiber membrane, and a membrane near the inner end face of the fixing part An external pressure type hollow fiber membrane module having a rubber-like elastic polymer material layer covering the periphery thereof.

With such a structure, the shear stress generated in the vicinity of the adhesive interface between the resin partition wall and the hollow fiber membrane due to the shaking of the membrane during the cross flow filtration and the aeration flushing washing is dispersed and relaxed. ,And,
It is possible to reduce the bending angle near the bonding interface of the hollow fiber membrane due to the membrane being drawn in when the backwash water is discharged. The module of the present invention includes a so-called cartridge type that is used by being housed in an outer housing.

The hollow fiber membrane used in the present invention is not particularly limited as long as it is used for fluid treatment. Examples of the material include polyacrylonitrile, polysulfone, polyether ketones, polyether sulfone, polyphenylene sulfide and polyfluoride. Vinylidene chloride, celluloses, polyvinyl alcohol, polyamide, polyimide, sulfonated polyphenylene ether, polyethylene, polypropylene, polybutene, poly-4-methylpentene, polyorganosiloxane, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, etc. Alternatively, a membrane formed by mixing or compounding may be used. The types of membranes include reverse osmosis membranes, nanofilters, ultrafiltration membranes, microfiltration membranes and degassing membranes. Further, the shape of the hollow fiber membrane has an inner diameter of 50 to 3000 μm.
Membranes having an inner / outer diameter ratio of 0.3 to 0.8 can be used.

The module case used in the present invention is
Diameter is 30mm-800mm, length is 300mm-3
The material selected from the range of 000 mm is polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer resin, ethylene-tetrafluoroethylene copolymer resin, fluororesin such as polyvinylidene fluoride, polyethylene, polypropylene, Polyolefin such as polybutene, polyvinyl chloride, polyester, polysulfone, polyether sulfone, polyphenylene ether and the like can be used.

In order to liquid-tightly bond and fix the module case and the hollow fiber membrane, a thermosetting polymer material such as epoxy resin, urethane resin or epoxy acrylate resin can be used. The resin partition wall is formed by fixing it in a liquid-tight manner. As the bonding method, a known method such as a centrifugal bonding method is used. Since the curing shrinkage and strength of the adhesive may be improved in some cases, the adhesive may further contain a fibrous material such as glass fiber or carbon fiber, or a fine powder such as carbon black, alumina or silica.

The rectifying cylinder used in the present invention is not particularly limited as long as it has a mainly cylindrical shape and can be arranged in the module case, but the portion facing the concentrated water discharge nozzle provided in the case. It is preferable to have a large number of openings on the side surface except for the reason that the liquid flow can be made uniform. 2 and 3 show examples of preferable shapes of the flow straightening cylinder. As the material of the flow straightening cylinder, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer resin, ethylene-tetrafluoroethylene copolymer resin, fluororesin such as polyvinylidene fluoride,
Examples thereof include polyolefins such as polyethylene, polypropylene and polybutene, polyvinyl chloride, polyester, polysulfone, polyether sulfone and polyphenylene ether.

The flow straightening cylinder is arranged around the hollow fiber membrane bundle facing the concentrated water discharge port on the side opposite to the side where the raw water supply port of the module is provided. Can also be installed. Examples of the disposing method include a method of fixing the rectifying cylinder at the same time when the module case and the hollow fiber membrane are adhered and fixed. The polymer material layer having rubber-like elasticity used in the present invention is for reinforcing the vicinity of the hollow fiber membrane adhesive fixing interface, and as the polymer material, for example, condensation type or addition type silicone rubber is used. The above silicone rubber is JIS cured
-Type A durometer hardness described in K6253 is 50
Less than is preferred. If the hardness is high, the bending of the hollow fiber membrane cannot be alleviated, and the hollow fiber membrane is broken at the reinforcing layer interface instead of the adhesive fixing interface, and the desired effect cannot be obtained.

The raw water supply port of the module comprises a through hole formed in the resin partition wall itself. The size of the opening depends on the diameter of the hollow fiber membrane, but each equivalent diameter is 2 to 30 m.
m. The shape of the opening is selected from a polygon such as a triangle, a quadrangle, and a hexagon, a circle, an ellipse, a fan, a C-shape, or a star. The number of openings depends on the cross-sectional area of the module, but it is possible to open 2 to 3000, and the positions of the openings are, for example, the intersections of the multiple circles and the radial lines on the resin partition wall surface, the intersections of the lattices, or For example, the positions of the vertices of many equilateral triangles.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples.

[0018]

Example 1 Polyacrylonitrile hollow fiber ultrafiltration membrane manufactured by Asahi Kasei Corporation (inner diameter 0.8 mm, length 1200)
mm, nominal cut-off molecular weight 13000) 1800 bundles,
The membrane bundle was stored in a module case made of transparent polysulfone having an outer diameter of 89 mm and a length of 1000 mm. Inside the nozzle portions on both sides of the module that are provided perpendicular to the length direction of the module case, the shape shown in FIG.
A polypropylene straightening cylinder having a diameter of m and a number of holes of 200) was arranged such that a portion having no opening faces the nozzle. Next,
Five polyethylene tube-like objects each having a length of 150 mm and an outer diameter of 12 mm were embedded in one side of the bundle in the arrangement as shown in FIG. 1, and a hollow fiber membrane bundle was formed by a centrifugal adhesion method using an epoxy resin. The module case, the straightening cylinder, and the tubular material were bonded.

After the epoxy resin was sufficiently cured, thermosetting silicone rubber was injected from the nozzles on both sides of the module case and cured to form a polymer material layer having a thickness of 10 mm. The hardness of the used silicone rubber after curing,
It was 41 when measured by the type A durometer hardness meter described in JIS-K6253. After the silicone rubber has been sufficiently cured, one side opens the hollow part of the hollow fiber membrane, and the other side opens the raw water supply port while the hollow fiber membrane remains closed with the epoxy resin. For this purpose, both end portions of the epoxy resin were partially cut, and five polyethylene tubes were removed.

Using the external pressure type hollow fiber membrane module manufactured as described above, river water having a turbidity of 2 to 20 was used as raw material water, filtration at a supply pressure of 120 KPa for 55 seconds, and backwashing at a supply pressure of 200 KPa. 5 seconds, flow rate 3 m ³ / Hr · a
The repeated test of aeration flushing for 30 seconds at t105 KPa was performed for about 5 months. When the module was inspected for leaks after the test was completed, no leak was confirmed. In addition, when this module was disassembled and the accumulation state of turbidity components in the module inside the hollow fiber membrane bundle was observed, the central part of each hollow fiber membrane bundle divided at the raw water supply port and the concentrated water discharge nozzle Accumulation of turbid components was not confirmed except on the opposite side.

[0021]

[Comparative Example] Except for using a thermosetting silicone rubber having a hardness of 58 after curing, which was measured by a type A durometer hardness meter according to JIS-K6253, without using a rectifying cylinder. The same external pressure type hollow fiber membrane module as in Example 1 was manufactured.

Using this external pressure type hollow fiber membrane module,
The same test as in Example 1 was performed. When the module was inspected for leaks after the test, it was confirmed that there were three leaks. When the module was disassembled to identify the leak location and the leak location was examined, the hollow fiber membrane was broken at the silicone reinforced interface near the concentrated water discharge nozzle at all three locations. From the positional relationship of the concentrated water discharge nozzle, it was presumed that the cause of the breakage was the drawing of the film into the concentrated water discharge nozzle. Further, when the accumulation state of the turbid component in the hollow fiber membrane bundle in the module was observed, the central portion of each hollow fiber membrane bundle divided by the raw water supply port and the concentrated water discharge nozzle were observed as in the example. Accumulation of turbid components was not confirmed except on the opposite side.

[0023]

Industrial Applicability According to the present invention, it is possible to provide an external pressure type hollow fiber membrane module which is excellent in drainage of physically washed waste water and which does not cause damage to the hollow fiber membrane near the hollow fiber membrane adhesion interface.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of the arrangement of raw water supply ports of an external pressure type hollow fiber membrane module of the present invention.

FIG. 2 is a perspective view showing an example of a straightening cylinder arranged in a module.

FIG. 3 is a perspective view showing another example of the flow straightening cylinder arranged in the module.

FIG. 4 is a schematic sectional view showing an example of the structure of the external pressure type hollow fiber membrane module of the present invention.

[Explanation of symbols]

 1 ... Tube material for forming raw water supply port 2 ... Hollow fiber membrane 3 ... Module case 4 ... Resin partition wall 5 ... Polymer material layer having rubber-like elasticity 6 ... Concentrated water Discharge nozzle 7 ... Raw water supply port 8 ... Rectifying cylinder

Claims (1)

[Claims] 1. In an external pressure type hollow fiber membrane module in which both ends of a bundle of a large number of hollow fiber membranes are adhesively fixed to a case by resin partition walls, raw water consisting of through holes formed in one resin partition wall itself. A supply port, a straightening tube arranged around the bundle end opposite to the raw water supply port, and a rubber-like elastic cover that covers the periphery of the membrane near the inner end face of the adhesive fixing part between the resin partition wall and the hollow fiber membrane at both ends. An external pressure type hollow fiber membrane module having a molecular material layer.