JPH02284631A - Membrane separator - Google Patents

Abstract

PURPOSE:To effectively utilize the surface of a hollow yarn membrane for membrane separating treatment by coaxially providing a hollow pipe in a pressure resistant cylindrical vessel and providing the hollow yarn membrane to one circumferential face part of the hollow pipe and communicating the inside of the hollow yarn membrane with the other circumferential face side of the hollow pipe. CONSTITUTION:A hollow pipe 2 is coaxially provided in a pressure resistant cylindrical vessel 1 and also a hollow yarn membrane 3 is provided to one circumferential face part of the hollow pipe 2. The inside of the hollow yarn membrane 3 is communicated with the other circumferential face side of the hollow pipe 2. As a result, suspended particles are hardly trapped by the hollow yarn membrane and plugging due to the suspended particles can be prevented. Therefore the surface of the hollow yarn membrane is effectively utilized for the film separating treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a membrane separation device, and particularly to a membrane separation device equipped with a hollow fiber membrane.

[Prior Art] In order to industrially utilize synthetic organic membranes (reverse osmosis membranes, ultrafiltration membranes, precision filtration membranes), it is necessary to take the form of modules processed for easy handling. The membrane separation units that make up this module are called elements (or modules). Elements (or modules) currently in practical use include ■Flat membrane (plate and frame), ■Spiral element, ■Hollow fiber module, and ■Tubular module. Both have advantages and disadvantages, but hollow fiber modules have the excellent features of high packing density and large membrane area. To manufacture hollow fiber modules, the end fixing process (botting)
, and the number of parts is small.

This hollow fiber module is used in large quantities in the manufacturing process of ultrapure water for semiconductor cleaning and medical water. Also, most dialyzers for artificial dialysis use this 1,000 joules.

Recently, synthetic membranes have been used not only for these purposes, but also for
It is expanding into fields such as solid-liquid separation in biological treatment, and permeation of valuable components in bacterial cells and enzyme suspensions. In such a system,
Activated sludge, solid particles such as bacterial cells and enzymes coexist at high concentrations. For this reason, it is difficult to apply an internal pressure type method in which a stock solution is introduced inside a hollow fiber for filtration because these particles clog the filter. Typically, external pressure types are used for these applications. However, since conventional modules have a high packing density of hollow fibers, the gaps between the hollow fibers are narrow, making it easy for particles to clog and stick together, reducing the effective membrane area. .

As a simple measure to solve this problem, reducing the packing density may be considered, but this would eliminate the advantage of the hollow fiber membrane module that the packing density can be high, and this is not a desirable solution.

In conventional modules using hollow fiber membranes, the tube axis direction of the container filled with the hollow fiber membrane bundle is aligned with the direction of the hollow fiber membrane bundle. The most commonly used configuration is one in which a synthetic resin partition wall is provided inside a cylindrical pressure-resistant container so as to be orthogonal to the cylinder axis. A hollow fiber membrane is implanted in this partition wall, and this hollow fiber membrane extends in the axial direction of the cylinder.

In such a membrane separation device, a blind spot where raw water accumulates tends to occur downstream of the partition wall in the raw water flow direction. In addition, raw water preferentially flows to the surrounding area of the hollow fiber membrane bundle, and raw water tends to stay inside the hollow fiber membrane bundle. From where such (m flow occurs,
Conventional membrane separation devices have the disadvantage that most of the filled membranes are not utilized, and if the raw water also contains suspended particles, this portion becomes clogged and solidified.

As a method to solve these problems, it has been considered to install a water conduit through the partition wall and allow raw water to flow out from the circumferential surface of the water conduit. It has also been considered to provide a passage water outlet on the side surface of the pressure vessel, and to arrange a partition wall having a hollow fiber membrane implanted across the outlet. However, in either case, when a large amount of suspended particles is included, there remains the problem that a solidified portion grows around the part of the particle blockage where a slight blind spot occurs.

[Problems to be Solved by the Invention] As mentioned above, in a membrane separation device using a conventional hollow fiber membrane module, there is a dead zone where raw water accumulates, and suspended components in the raw water are concentrated in this dead zone. , solidified,
There was a problem that the effective membrane area became small.

[Means for Solving the Problems] The membrane separation device of the present invention includes a cylindrical pressure-resistant container, a hollow tube provided coaxially within the pressure-resistant container, and one peripheral surface portion of the hollow tube. and a hollow fiber membrane implanted in the hollow fiber membrane, the interior of the hollow fiber membrane communicating with the other circumferential surface of the hollow tube.

[Function] In the membrane separation device of the present invention, raw water is passed through the pressure vessel so as to come into contact with the outer surface of the hollow fiber membrane.

The water that has passed through the hollow fiber membrane flows from inside the hollow fiber membrane to the side of the hollow tube opposite to the peripheral surface on which the hollow fiber membrane is planted, and then is taken out from the membrane separation device.

In the membrane separator of the present invention, since there is no stagnation point for the flow of raw water, concentration and solidification of suspended components are prevented.

[Example] Examples will be described below with reference to the drawings.

Fig. 1 is a sectional view along the sleeve direction of a pressure vessel in a membrane separation device according to an example, Fig. 2 is a sectional view taken along the line +I-II in Fig. 1, and Fig. 3 is an enlarged view of the main part of Fig. 2. be.

The pressure-resistant container designated by the reference numeral 1 has a cylindrical portion 1a and head plate portions 1 at both ends.
The end plates lb and lc are respectively provided with an inlet 1d and an outlet 1e for raw water.

A hollow tube 2 is installed inside the pressure vessel 1, and hollow fibers 11j extend radially from the outer peripheral surface of the hollow tube 2.
3 is implanted in the hollow tube 2.

As shown in FIG. 3, on the proximal end side of the hollow fiber membrane 3,
The inside of the hollow fiber membrane 3 communicates with the inside of the hollow tube 2, and the internal passage of the hollow fiber membrane is closed on the tip side of the hollow fiber [1i3.

One end of the hollow tube 2 is connected to a connector vibe 5 via a joint 4, and the connector vibe 5 extends outside the pressure vessel 1. The other end of the hollow tube 2 is sealed with a cap 6.

In the membrane separation apparatus of FIGS. 1 to 3 configured in this way, raw water flows into the pressure vessel 1 from the inlet 1d and flows between the hollow tube 2 and the pressure vessel 1 toward the outlet 1e. . During this time, water that comes into contact with the hollow fiber membrane 3 and permeates through the hollow fiber membrane 3 flows within the hollow fiber membrane 3 toward the hollow tube 2 . Then, the permeated water flows through the hollow tube 2 and the connector pipe 5 in this order, and is taken out from the membrane separator.

In the membrane separation device according to this embodiment, the following effects (1) to (4) are achieved.

■ Compared to conventional hollow fiber elements, the length of each hollow fiber membrane (code 3) is shorter, so it is possible to reduce the passage resistance of permeated water and increase the effective pressure difference between the membranes. can.

■ The length of each hollow fiber is short, and the tip is not fixed (that is, the hollow fiber membrane 3 has only its proximal end fixed to the hollow tube 2, and the distal end is a free end). ). Therefore, it does not trap the mass of suspended particles that form the core of the blockage.

(2) This makes it possible to effectively utilize the surface of the filled hollow fiber membrane.

■ By connecting hollow tubes that collect permeated water, multiple components can be filled into a single container. (In Figures 1 to 3, one hollow tube 2 is inserted into one pressure vessel 1, but when the length of the pressure vessel 1 is long, multiple hollow tubes 2 may be connected together. It is only necessary to insert the membrane element into one pressure-resistant container 1.) This makes it easy to replace the membrane element and also reduces the unit price of the membrane.

The membrane element described above can be manufactured by the following method (see FIGS. 4 to 8).

(i) In the hole portion of the rigid porous hollow tube 2,
The hollow fiber membrane 3 cut to a predetermined length is planted. Thereafter, a curable liquid elastic material (e.g., silicone rubber, urethane resin, flexible epoxy resin) indicated by reference numeral 7 is filled into the gap between the planted hollow fiber membrane bundles and cured at room temperature or by heating. This seals the gap between the hollow fiber membrane and the hollow tube.

One end of the hollow fiber used is sealed in advance with a curable liquid elastic material similar to that described above, but it may also be sealed by a method such as thermal welding. Further, after the porous hollow tube is flocked and solidified, it may be sealed by the above-mentioned means.

The inner circumferential surface of the hollow tube is scraped to a predetermined extent to expose the end surface of the hollow fiber membrane inside the hollow tube.

By this method, one component is manufactured (FIGS. 4 to 7).

(ii) When the hollow fibers used in the above method are used as a porous support material, an ultrafiltration membrane or a reverse osmosis membrane may be coated on the support material.

(1) A hollow fiber membrane element having the function of an ultrafiltration membrane or a reverse osmosis membrane is manufactured by immersing the element manufactured by a method similar to the above in a specified membrane-forming dope solution and further immersing it in a gelling solution. can.

(iii) After the hollow fibers are implanted around the dummy tube, the implanted portion is solidified with a curable liquid elastic material, thereby making it possible to manufacture an element in which the hollow fibers are homogeneously arranged. The dummy tube is removed and the solidified portion is scraped off to expose the end surface of the hollow fiber membrane.

As shown in FIG. 8, in order to implant hollow fibers around the dummy tube 8, one end of the hollow fiber membrane 3 cut to a predetermined length is connected to the weft thread 9.
You can use the method of wrapping the woven material.

Another embodiment of the present invention will be described with reference to FIGS. 9-11.

A large-diameter hollow tube 8 is inserted into the pressure-resistant passenger device 1.

The hollow fiber membrane 3 is implanted in the hollow tube 8 so as to extend in the radial direction from the inner peripheral surface of the hollow tube 8. In this embodiment, three hollow tubes 8 made of pressure-resistant synthetic resin are inserted into the pressure-resistant container 1.

A pair of flanges 8a are provided around the outer periphery of both ends of the hollow tube 8, and a seal ring (V ring) 9 is installed in a groove between the flanges 88.

This seal ring 9 defines a permeated water extraction chamber 10 between the outer circumferential surface of the hollow tube 8 and the inner circumferential surface of the pressure vessel 1 .

The pressure vessel 1 is provided with a permeated ice outlet 11 for taking out permeated water from each extraction chamber 10.

The hollow fiber membrane 3 is held with its base end embedded in the hollow tube 8. The inside of the hollow fiber membrane 3 communicates with a permeated water extraction chamber 10 at its base end side.

The tip of the hollow fiber membrane 3 is sealed as shown in FIG. This hollow fiber membrane 3 has a length smaller than the radius of the hollow tube 8. Note that the hollow fiber membrane 3 has the above-mentioned (1) to (i
It can be fixed to the hollow tube 8 by a method similar to ii). (In the case of (Iiii), the outer circumferential surface of the hollow tube 8 may be ground.) As is clear from the above explanation, on the inside of the hollow tube 8, the closer it is to the axis of the hollow tube 8, the more hollow it becomes. The packing density of the hollow fiber membranes 3 is high, and the packing density of the hollow fiber membranes 3 becomes lower toward the inner peripheral surface of the hollow tube 8.

In the membrane separator shown in Figures 9 to 11, the raw water is inlet 1.
d into the pressure vessel 1, and flows into the hollow tube 8 through the outlet 1e.
During this time, it comes into contact with the hollow fiber membrane 3.

The water that has permeated through the hollow fiber membrane 3 is transferred from inside the hollow fiber membrane 3 to the extraction chamber 1.
0, and then taken out from the membrane separation device through the outlet 11.

In the membrane separation apparatus shown in FIGS. 9 to 11, the following effects (1) to (4) are achieved.

■ The part of the hollow fiber membrane with the highest degree of freedom is located at the center of the tube.

■ The hollow fiber membrane is fixed, and the membrane packing density is the lowest at the part with the least degree of freedom.

■ Raw water is introduced parallel to the tube axis, creating a flow velocity distribution within the tube due to the hollow fiber membrane. Therefore, (a) the flow velocity is highest at the center of the pipe, and (b) the flow velocity is second highest at the periphery of the pipe.

(c) The flow velocity decreases in the center of the tube where the membrane packing density is high.

(2) Although the flow velocity is low in the area where the membrane packing density is high, blockage by suspended particles hardly occurs because the degree of freedom of the hollow fiber membrane in this area is high.

■ Also, in the area around the tube where the membrane is fixed, the membrane packing density is low, so the flow velocity inside the tube increases, which prevents the capture of suspended particles.

■ Even if suspended particles are captured, the distance from the center of the tube to the other free end is short, which encourages the captured particles to leave again.

■ Therefore, the surface of the hollow fiber membrane can be used effectively.

■ Since the length of the hollow fiber membrane is short, the resistance to passage of permeated water is small, and the effective pressure difference between the membranes can be increased.

[Effects] As described above, according to the membrane separation device of the present invention, the hollow fiber membrane hardly captures suspended particles, and blockage due to suspended particles can be prevented. Therefore, the surface of the hollow fiber membrane can be effectively used for membrane separation treatment.

In the membrane separation device of the present invention, since the length of the hollow fiber membrane is only short, the resistance to permeation is low.

Therefore, the effective differential pressure between the membranes can be increased.

In the membrane separation device of the present invention, a plurality of elements can be filled into one pressure vessel by connecting hollow tubes.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment, and Fig. 2 is an If of Fig. 1.
-II line sectional view, FIG. 3 is an enlarged view of the main part of FIG. 2, FIG. 4, FIG. 5, FIG. 6, FIG. 7, and FIG. FIG. 9 is a sectional view showing another embodiment, FIG. 10 is a sectional view taken along the line X--X in FIG. 9, and FIG. 11 is an enlarged view of the main part of FIG. 10. DESCRIPTION OF SYMBOLS 1...Pressure container, 2...Hollow tube, 3...Hollow fiber membrane, 8...Hollow tube.

Claims (1)

[Claims] A cylindrical pressure-resistant container, a hollow tube provided coaxially within the pressure-resistant container, and a hollow fiber membrane implanted on one peripheral surface of the hollow tube, A membrane separation device characterized in that the inside communicates with the other peripheral surface side of the hollow tube.