JPH0779953B2 - Hollow fiber type 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 hollow fiber type module used for liquid separation and purification. More specifically, the present invention relates to a hollow fiber type module preferably applied to so-called external pressure filtration, in which a stock solution is introduced from the hollow fiber outer wall side to obtain a filtrate from the hollow fiber inner wall side.

[0002]

2. Description of the Related Art A hollow fiber type module used in conventional internal pressure filtration (a system in which a stock solution is introduced from the inner wall side of a hollow fiber to obtain a filtrate on the outer wall side), in particular, a nozzle is arranged on the end side surface. A module in which a large number of hollow fibers are stored in a cylindrical case is used for external pressure filtration as it is, and the hollow fibers in the vicinity of the stock solution introduction nozzle receive a large force due to the stock solution flowing into the module and are densely focused, The liquid did not go into the bundle, and in some cases it was damaged. In order to avoid this, the hollow fiber bundle is wrapped with a synthetic resin net, a baffle plate is provided near the opening of the nozzle, or a cylindrical prevention wall is provided between the case and the hollow fiber bundle. .

However, in these hollow fiber modules, there is a problem that the hollow fiber is not subjected to liquid pressure because the undiluted solution introduced from the nozzle impinges on the baffle plate or the prevention wall, and the filtration capacity is insufficient. . The present inventors have already addressed this problem in Japanese Patent Application No. 2-2733.
As indicated by No. 74, a solution is provided by providing a straightening cylinder at the end of the yarn bundle and increasing the inner diameter of the nozzle as it approaches the straightening cylinder.

[0004]

However, even in the method of Japanese Patent Application No. 2-273374, there is a problem that the filtration capacity is lowered early when the quality of the raw water is poor. This is presumed to be because the flow of the undiluted solution on the inner surface of the case has a slow flow rate due to the distribution in the circumferential direction, and the progress of fouling on the membrane surface starts from there.

It is an object of the present invention to provide a hollow fiber type module which is excellent in filtration ability and can be stably operated for a long period of time (with little change in increase in filtration pressure).

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a hollow fiber type module comprising a cylindrical case having a stock solution introducing nozzle on at least one end side surface in which a bundle of a large number of hollow fibers is housed. The hollow fiber bundle of the undiluted solution introducing nozzle is surrounded by a cylindrical rectifying cylinder, and the inner diameter of the case inner wall side of the undiluted solution introducing nozzle that opens toward the rectifying cylinder is larger toward the rectifying cylinder, and The hollow fiber module is characterized in that the inner diameter of the cylindrical case has a taper such that it becomes smaller toward the center of the cylindrical case at the portion facing the rectifying cylinder.

1 and 2 are schematic sectional views showing an example of the present invention. As the rectifying cylinder used in the present invention, any one having strength and elution resistance can be used, but the same member as the case and a molded product of plastic such as polyethylene or polypropylene are preferably used. Further, although these rectifying cylinders may be provided at both ends, they have to be used at least at one end.

The rectifying cylinder may have a cylindrical shape or a polygonal cylindrical shape, but the cylindrical shape is preferable. The outer diameter of the straightening cylinder is preferably about 98 to 50% of the minimum inner diameter of the cylindrical case portion existing outside thereof. If it exceeds 98%, the pressure loss is large, and if it is less than 50%, the number of hollow fibers that can be filled becomes small, and the processing capacity per module becomes small.

The length of the straightening cylinder is preferably about 3 to 20% of the length of the yarn bundle, excluding the portion buried in the adhesive at the end.
If it is less than 3%, the effect of rectification is reduced, the amount of water permeation is reduced, and yarn breakage may occur, which is not preferable. On the other hand, if it exceeds 20%, the water permeability tends to decrease, which is not preferable. The rectifying cylinder may have a hole in the part filled with the adhesive in order to increase the adhesive strength,
Further, a protrusion 7 may be provided for fixing to the cylindrical case 3 (FIGS. 3 and 4). The undiluted solution introduction nozzle 2 forms a smooth flow of the solution and flows into the cylindrical case 3.
It is preferably arranged adjacent to the adhesive layer 5 at the end of the yarn bundle (FIG. 2). Further, there may be a drain hole on the side surface of the straightening cylinder at a position near 90 ° with respect to the inflow direction of the stock solution introducing nozzle 2.

The present invention is characterized in that the inner diameter of the case side of the stock solution introducing nozzle opened toward the flow straightening cylinder becomes larger as it approaches the flow straightening cylinder. That is, in FIG. 1, the flow straightening cylinder 1 is provided on the outer periphery of the end of the hollow fiber bundle on the side where the liquid is introduced, and the nozzle 2 that opens toward the straightening cylinder 1 has an inner diameter on the case side at the opening. It is increasing.

The liquid introduced from the undiluted solution introduction nozzle 2 into the cylindrical case 3 collides with the straightening cylinder 1 interposed between the cylindrical case 3 and the bundle of hollow fibers 4, and then between the straightening cylinder and the cylindrical case. It flows through the annular gap 6 and is supplied to the hollow fiber bundle. At that time, if the inner diameter of the stock solution introducing nozzle on the side of the cylindrical case becomes larger toward the straightening cylinder, the pressure loss of the solution at the same pressure decreases. The inner diameter of the stock solution introduction nozzle is
As long as it increases near the opening on the cylindrical case side,
It does not matter even if there is a thin part in the middle of the undiluted solution introduction nozzle. The method of increasing the inner diameter may be linear or curved, but as shown in FIG. 1, the shape in which the inner wall of the opening to the case has R is most preferable.

The module according to the present invention exhibits remarkable effects when used in a high flow rate range. In the high flow rate region, the linear velocity of the liquid in the nozzle is generally 0.5 m / sec or more.
The present invention is particularly effective when used at a linear velocity of 1.0 m / sec or more. Further, in the present invention,
It is characterized in that the inner diameter of the cylindrical case has a taper such that it becomes smaller toward the center of the cylindrical case at the portion facing the rectifying cylinder.

The inner diameter of the cylindrical case forms a gradual taper toward the center of the cylindrical case at the portion facing the rectifying cylinder, but θ in FIG. 6 is 45 ° or less,
It is preferably 30 ° or less and 5 ° or more. The ratio of the decrease in the inner diameter is preferably 5% or more and less than 20% with respect to the inner diameter of the case end portion on the side where the rectifying cylinder is arranged. If it is less than 5%, it is difficult to obtain a uniform flow along the flow straightening cylinder when the stock solution flows in, and the deterioration of the filtration capacity over time tends to increase. or,
When it is 20% or more, it is difficult to handle because the end is thicker than the center of the module. Further, as for the narrowed portion, it may be the whole or a part of the portion facing the straightening cylinder.

A sharp step (for example,
When there is a level difference such that θ exceeds 45 ° in FIG. 6, the pressure loss becomes large, and when the case inner diameter does not change, it is difficult for a circular tubular uniform flow to be formed, and dirt does not form on the membrane. Easily deposited on the outer surface. The inner diameter of the case is not limited to the part of the straightening cylinder that does not face. Further, a normal porous cylindrical body may be arranged between the yarn bundle and the cylindrical case, or nothing may be arranged.

The yarn bundle may be wrapped around a synthetic resin net individually or in a divided manner, or may be wrapped around nothing. The material of the case is not particularly limited, but in terms of strength, moldability and elution property, polyvinyl chloride, polycarbonate,
Polysulfone, polyether ether ketone, PFA
A synthetic resin such as (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) or polyvinylidene fluoride is preferably used.

In the present invention, the inner diameter of the cylindrical case is
It becomes smaller toward the center of the cylindrical case in the portion facing the flow straightening cylinder. There are various methods to make a case with such an inner diameter, but in general, a pipe with a uniform thickness is formed by extrusion molding, the inside of the end of this pipe is shaved diagonally, and separately molded by injection molding. It can be obtained by a method of joining the above described module end member 9 with a nozzle by adhesion or welding.

The present invention exhibits a particularly remarkable effect when the cylindrical case is joined by adhering or welding the portion having the nozzle on the end side surface and the cylindrical pipe. In the conventional joint type module, there is a step on the inner surface of the joint,
This is because it was the source of flow resistance and drift.

[0018]

The present invention will be described in more detail with reference to the following examples.

[0019]

Example 1 Hollow fiber ultrafiltration membrane made of polysulfone (inner diameter 0.65 mm, outer diameter 1.10 mm, pure water permeation rate 1.35)
l / Hr · kg / cm ² · m · 25 ° C) 7200 pieces are stored in a polysulfone cylindrical case with nozzles on both sides and a minimum inner diameter of 130 mm, an outer diameter of 124 mm and an effective length (embedded in adhesive) The length of the hollow fiber is 130 mm, and the both ends of the hollow fiber are liquid-tightly sealed with an epoxy adhesive and the effective hollow fiber length is 930.
A double-sided water collecting module having a size of 2 mm was assembled.

The inner diameter of the nozzle opening toward the flow straightening cylinder at the substantially central portion was 33 mm, and the corner formed by the nozzle and the case was rounded 5R from the position 5 mm from its apex. The inner diameter of the case is 143 mm at both ends, and is 28 mm at the bonded portion to the pipe, and is thinned to 130 mm (θ is about 13 °). In this module case, a head part with a nozzle and a pipe part with a wall thickness of 5 mm without a nozzle are separately molded and assembled by adhesion, but there is no substantial step and the part facing the rectifying cylinder is the case. In order to reduce the inner diameter toward the center of the case,
As shown in Fig. 2, the inner surface of the pipe is sharpened.

From the nozzle opened toward the straightening cylinder, 25
Deionized water at ℃ was supplied to the module at 9.5m ³ / hr, 0.5m ³ / hr was extracted from the nozzle 2'as concentrated liquid, and 9m ³ / h
The r was filtered. Pressure required for filtration

[0022]

[Equation 1]

Here, P _i ; stock solution inlet pressure kg / cm ² P ₀ ; stock solution outlet pressure kg / cm ² Pf ₁ ; filtrate outlet 1 pressure kg / cm ² Pf ₂ ; filtrate outlet 2 pressure kg / cm ² in 5 minutes after the start it was 1.00 kg / cm ^2, after performing filtration continuously 200 hours was 1.01 kg / cm ^2.

There was no yarn breakage after 200 hours of operation.

[0025]

[Example 2] A corner of the inner surface of the pipe is bent, and the inner diameter of the case is 143 mm at both ends, but it is thinned to 130 mm over 14 mm at the bonded portion with the pipe (θ is about 25 °). A module similar to that of Example 1 was prepared except for the above. Example 1 and was 9.5 m ³ / hr feed to similarly the module of pure water 25 ° C., was subjected to filtration of 9.0 m ³ / hr. The pressure P required for filtration was 1.01 kg / cm ² 5 minutes after the start of water flow, and was 1.03 kg / cm ² after filtration was continuously performed for 200 hours.

There was no yarn breakage after 200 hours of operation.

[0027]

[ Third Embodiment] The corner of the inner surface of the pipe is bent, and the inner diameter of the case is 143 mm at both ends, but it is thinned to 130 mm over 5.5 mm at the bonded portion with the pipe (θ is about 45 °). Other than the above, a module similar to that of Example 1 was prepared. It was performed filtration of 9.5 m ³ / hr feed and 9.0 m ³ / hr in the module of pure water similarly 25 ° C. Example 1. The pressure P required for filtration was 1.01 kg / cm ² after 5 minutes from the start of water flow, and 1.05 kg / cm ² after continuous filtration for 200 hours.

There was no yarn breakage after 200 hours of operation.

[0029]

Comparative Example 1 A pipe similar to that used in Example 1 was used without cutting the inside of the end. On the inner surface of the case, there was a sharp step having a height of 5 mm with θ of 90 ° at the joint with the pipe. When the same filtration as in Example 1 was carried out, 9.0 m ³
For the filtration of / hr, 1.03 kg / cm ^{2 was} required 5 minutes after the start of filtration, and the filtration pressure after 200 hours of operation increased to 1.10 kg / cm ² .

[0030]

According to the present invention, the filtration capacity is large,
Moreover, it is possible to provide a module that is stable over time (small increase in filtration pressure).

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a hollow fiber type module of the present invention.

FIG. 2 is an explanatory view showing another example of the hollow fiber type module of the present invention.

FIG. 3 is an explanatory view showing an example of a cross section of a flow straightening cylinder used in the present invention.

FIG. 4 is an explanatory view showing an example of a rectifying cylinder used in the present invention.

FIG. 5 is a diagram illustrating two examples of how to change the inner diameter of the nozzle used in the present invention.

FIG. 6 is a diagram illustrating an example of how to change the inner diameter of the cylindrical case used in the present invention.

[Explanation of symbols]

 1 Cylindrical Rectifying Tube 2, 2'Nozzle 3 Module Case 4 Hollow Fiber 5 Adhesive 6 Cylindrical Gap 7 Porous Cylindrical Body 8 Cap 9 Nozzle End Member 10 Pipe Part

Claims (1)

[Claims] 1. A hollow fiber type module in which a bundle of a large number of hollow fibers is housed in a cylindrical case having a stock solution introducing nozzle on at least one end side surface, and a hollow fiber bundle of the stock solution introducing nozzle section is provided. Is surrounded by a cylindrical straightening cylinder, the inner diameter of the case of the stock solution introducing nozzle opening toward the straightening cylinder increases toward the straightening cylinder, and the inner diameter of the cylindrical case is straightened. A hollow fiber type module having a taper such that a portion facing a cylinder becomes smaller toward a central portion of a cylindrical case.