JPH0618615B2 - Membrane separation device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a membrane separation device, and particularly to a membrane separation device suitable for microfiltration.

<Prior art> Conventionally, as a microfiltration device, the stock solution is supplied from one of the porous tubular separation elements made of ceramic or sintered metal, and the permeated liquid (filtrate) is in a direction orthogonal to the flow direction. There is known a so-called cross-flow type in which the tube wall is permeated to obtain.

In addition, a flat membrane filter membrane for microfiltration has been proposed. To perform microfiltration using this filter membrane, the filter membrane is fixed to a porous membrane support plate and the membrane support plate is placed opposite to the membrane support plate. The undiluted solution is supplied from the side of the filtration surface, and the permeated solution is obtained through the porous membrane support plate.

<< Problems to be Solved by the Invention >> However, in the above-described conventional microfiltration apparatus using a tubular separation element, in order to obtain a large amount of permeated liquid,
The stock solution flow rate in the pipe must be kept high,
For this reason, the circulation pump has a large capacity, and thus has a drawback of being a device with large power consumption.

In addition, since a certain pressure is applied to the inside and outside of the pipe during the filtration and backwashing processes, it is necessary to increase the wall thickness of the pipe to withstand the pressure, which causes a drawback of increasing filtration resistance. .

Further, increasing the wall thickness of the pipe has a problem that extra material is required for that amount and the cost is increased.

Further, in the microfiltration using the filter membrane, there is a disadvantage that the backwashing cleaning cannot be effectively performed when the filter membrane is clogged. That is, in the backwash cleaning, there is a risk that the backwash pressure may damage the filter membrane unless a holding member for supporting the filter membrane is provided on the feed side of the stock solution.

<Means for Solving Problems> The present invention has been made to solve the above problems, and a groove is formed by a groove and a groove on the front surface side and the back surface side of the substrate. In a membrane separation device having a liquid collection part that is formed by stacking a plurality of filtration plates with filter membranes on the liquid collection part, the directions of the grooves of the liquid collection parts of the facing filtration plates are opposite to each other. It is characterized by being arranged so as to intersect.

<Operation> The present invention has the above-described configuration, and at the time of the membrane separation (filtration) step, the undiluted solution flows to one surface side of the filtration membrane stretched on the filtration plate, and the other surface side of the filtration membrane is collected. The permeated liquid is obtained from the part, and the cleaning liquid is supplied from the other surface side of the filter membrane during the cleaning step, and the cleaning waste liquid is obtained from the one surface side. Further, during the washing process, one surface side of the filter membrane acts so as to be held by the laminated filtration plates.

<< Example >> Hereinafter, the present invention will be described based on illustrated examples.

FIGS. 1 to 4 show a filter plate 1 used in the membrane separation device according to the present invention, in which an elongated upper opening is formed on each of the upper and lower ends of a rectangular flat substrate 2 made of synthetic resin. 3, a lower opening 4 is provided.

Denoted at 5a and 5b are liquid collecting parts formed on the inside of the front surface side and the back surface side of the substrate 2, of which 5a is a vertical type liquid collecting part provided on the front surface side of the substrate 2 and is located above and below the substrate 2. A groove is formed by the vertical groove 6a extending in the direction (longitudinal direction) and the vertical projection 7a, while the horizontal liquid collecting part 5b is formed by the horizontal groove 6b and the horizontal groove extending in the horizontal direction of the substrate 2. A groove is formed with the portion 7b. Therefore, the directions formed by the grooves formed by the concave stripes and the convex stripes of the vertical liquid collecting portion 5a and the horizontal liquid collecting portion 5b are in a relationship of being orthogonal to each other.

Although both the vertical liquid collecting portion 5a and the horizontal liquid collecting portion 5b shown in the figure are formed with only a few vertical concave stripes 6a, vertical convex stripes 7a, horizontal concave stripes 6b, and horizontal convex stripes 7b. A large number are provided on the actual filter board 1. In addition, these vertical groove 6
The width of a and the lateral groove 6b are in the range of 5 to 30 mm, and
The width of the vertical ridges 7a and the horizontal ridges 7b is selected from the range of 0.5 to 3 mm, and the depths of the vertical ridges 6a and the vertical ridges 6b (the vertical ridges 7a and the horizontal ridges 7a The height of the strip portion 7b) is 0.5 to
It is formed by selecting from the range of 3 mm.

Which device is selected from these ranges is determined by the type of stock solution, the supply pressure of the stock solution, and the like.

Reference numeral 8 denotes a filter membrane for precision filtration, which is made of a flexible and porous synthetic resin and covers the entire surfaces of the vertical liquid collecting portion 5a and the horizontal liquid collecting portion 5b, and the vertical liquid collecting portion 5a. Also, it is fixed and stretched by a holding packing 10 in a ring-shaped groove 9 provided around the horizontal liquid collecting section 5b.

Reference numeral 11 is a gasket inserted in a ring-shaped groove 12 provided on the front surface side of the substrate 2, and the surface of the gasket 11 is slightly projected from the surface of the substrate 2.

Further, 13 is a permeated liquid discharge passage provided at both end portions of the substrate 2, and is designed to communicate with the vertical concave streak portion 6a and the horizontal concave streak portion 6b. In addition, each vertical groove 6a, 6a ...
Further, communication grooves 14 are provided by notching the end portions of the vertical convex strips 7a, 7a ... And the horizontal convex strips 7a, 7a ... so that the horizontal concave strips 6b, 6b ...

The substrate 2 has an upper opening 3, a lower opening 4, and a vertical liquid collecting section 5.
a, the horizontal type liquid collecting part 5b, the permeated liquid discharge port 13, and the ring-shaped groove parts 9 and 12 are integrally formed.

To assemble the membrane separation device a using the filtration plate 1 described above,
As shown in the exploded perspective view of FIG. 5, a large number of filter plates 1 (three in the figure, but usually several tens in the drawing) having filter membranes stretched on the front surface side and the back surface side are laminated, and One end plate 16 having the stock solution supply port 15 and the other end plate 18 having the concentrated solution discharge port 17 are pressed from both sides to assemble. Although the pressing means for the both end plates 16 and 18 is not shown here, they are pressed by a so-called normal filter pressing method.

Further, as shown in FIG. 6, if the surfaces of one of the successive filtering plates are vertical type liquid collecting parts 5a, the other filtering plates are horizontal type, as shown in FIG. It is arranged so as to serve as the liquid collecting portion 5b.

Further, the upper openings 3, 3 ... And the lower openings 4, 4 ... Are communicated with each other by laminating the respective filtering plates 1, 1, ..., Thus, an upper passage 3 ′ and a lower passage 4 ′ are formed.

Now, in order to perform a membrane separation (filtration) process using the membrane separation device a, as shown in FIG. 7, when the stock solution is supplied from the stock solution supply port 15 of one end plate 16, each of the filtration plates 1 The stock solution flows from the lower passage 4'formed by the lamination of 1 ... To the upper passage 3 '.

During the flow of the undiluted solution from the lower passage 4'to the upper passage 3 ', part of the undiluted solution passes through the filter membrane 8 and the filtration plates 1, 1
Are collected in the vertical concave streak portions 6a and the horizontal concave streak portions 6b, and the collected permeated (filtered) liquid is discharged from the permeated liquid discharge passage 13 and then sent out of the system via the cleaning liquid tank b. .

The stock solution that has reached the upper passage 3'is discharged from the concentrated solution discharge port 17 provided on the other end plate 18, and is circulated again in the stock solution tank (not shown). The concentrated solution is appropriately throttled by a throttle valve (not shown) to maintain the stock solution supply pressure at a predetermined pressure.

The filtration membrane 8 comes into contact with the bottoms of the vertical groove portions 6a and the horizontal groove portions 6b due to the supply pressure of the undiluted solution (the third, fourth
(Refer to the drawing), since the widths of the vertical concave streak portions 6a and the horizontal concave streak portions 6b are 5 to 30 mm as described above, a vortex or turbulent flow is generated in the undiluted solution flowing therethrough, and It is possible to effectively prevent the generation of concentration polarization, the formation of a gel layer, and the deposition of contaminants (contaminants).

However, if the membrane separation process is carried out for a long time, the filter membrane 8 becomes clogged or is in a compacted state, and the amount of the permeated liquid is reduced.

In this backwash cleaning, the supply of the stock solution is stopped, or the valve V ₁ provided in the cleaning solution tank b is closed while the stock solution is still flowing to stop the outflow of the permeate to the outside of the system, and through the valve V _2. The pressurized air is introduced into the cleaning liquid tank b. As a result, the permeated liquid in the cleaning liquid tank b flows out to the raw solution supply side through the filter membrane 8, that is, in the direction opposite to that in the membrane separation process, and adheres to the surface of the filter membrane 8 on the raw solution supply side. The existing contaminants are removed by backwashing and the backwashing waste liquid is discharged to the outside of the system through the stock solution supply path.

Moreover, at the time of this backwashing, the expansion of the filter membrane due to the backwashing is caused by the line contact by the vertical ridges 7a, 7a ... And the horizontal ridges 7b, 7b. Since it is suppressed by, it can be effectively performed without damaging the filter membrane.

When the performance of the filtration membrane 8 is recovered by the above backwashing process, the process proceeds to the membrane separation process again.

In the above membrane separation treatment, the stock solution was supplied to the lower passage 4'formed by stacking the filtration plates 1, 1 ... And the concentrated liquid was discharged from the upper passage 3 '. You may reverse. That is, the stock solution may be supplied from the upper passage 3'and the concentrated liquid may be discharged from the lower passage 4 '.

Furthermore, two types of liquid collecting portions, namely, a vertical liquid collecting portion 5a and a horizontal liquid collecting portion 5b are formed on the front surface side and the back surface side of the above-described filter plate 1. As shown in FIG. One of the front plates and a back plate 1a having vertical liquid collecting parts 5a on the back side, and the other plate having front and back surfaces having horizontal liquid collecting parts 5b 1b
It is also possible to make two kinds of the above and these layers 1a and 1b alternately laminated.

Even by using such two kinds of filter plates 1a, 1b, the vertical convex strips 7a, 7a ... Or the horizontal convex strips of the filter plate 1a or 1b, which are arranged in succession on the surface side of the filter membrane 8 in contact with the stock solution. Part 7
Since it can be held by b, 7b, ..., It can be effectively backwashed without damaging the filter membrane 8.

In addition, in the above-mentioned embodiment, when the filter membranes are laminated, the groove direction of the vertical liquid collecting portion 5a and the horizontal liquid collecting portion 5b are exactly orthogonal to each other, but they do not necessarily need to be orthogonal.
It can be adopted if it is not parallel. For example, the groove direction of the vertical liquid collecting portion 5a may be set to an angle of 45 ° upwards to the right, and the groove direction of the horizontal liquid collecting portion 5b may be set to an angle of 45 ° to the left.

Further, although the microfiltration membrane is used as the filtration membrane in the above-mentioned embodiments, it is also possible to use an ultrafiltration membrane, a reverse osmosis membrane or other semipermeable membrane.

In the above-described embodiments, the membrane separator is constructed by laminating the filtration plate on which the filter membrane is stretched on the integrally molded substrate, so that the membrane separator can be manufactured at low cost.

In addition, the filter plate is provided with two types of vertical liquid collecting part and horizontal liquid collecting part, and these are laminated so as to face each other. Therefore, backwashing and washing should protect each other's filter membrane. Therefore, the filter membrane is not damaged.

Moreover, since the width of the vertical groove and the width of the horizontal groove are sufficiently large, a swirling or turbulent flow occurs in the flow of the undiluted solution, which prevents concentration polarization or the development of a gel layer, and is also effective in depositing contaminants. Since it can be prevented, the membrane separation device can slowly increase the differential pressure.

<< Effects of the Invention >> The present invention is such that, when the filtration plates stretched with the filter membrane are laminated, the groove directions of the liquid collecting portions of the filtration plates which come in contact with each other are crossed, so that when backwashing and washing. Since the filter membrane is held by the groove portion of the partner, it has the effect of not damaging the filter membrane.

[Brief description of drawings]

The drawings show an embodiment of the membrane separation device according to the present invention. Fig. 1 is a front view of a filtration plate, Fig. 2 is a rear view of the filtration plate, and Fig. 3 is III of Fig. 1. -III sectional view, FIG. 4 shows the first
Fig. 5 is a sectional view taken along line IV-IV in Fig. 5, Fig. 5 is an exploded perspective view of the membrane separation device, Fig. 6 is a vertical cross-sectional view showing a laminated state of the filtration plates, and Fig. 7 is a schematic diagram showing a membrane separation process of the membrane separation device. FIG. 8 and FIG. 8 are vertical cross-sectional views showing a laminated state of another filter plate. 1 ... Filter 2 ... Substrate 3 ... Upper opening 4 ... Lower opening 5a ... Vertical liquid collecting part 5b ... Horizontal liquid collecting part 6a ... Vertical concave line part 6b ... Horizontal concave line part 7a ... … Longitudinal ridges 7b …… Horizontal ridges 8 …… Filtration membrane 13 …… Permeate discharge port a …… Membrane separation device

Claims (1)

[Claims] 1. A substrate having a liquid collecting portion in which a groove is formed by a concave portion and a convex portion on the front surface side and the back surface side of the substrate, and a large number of filtration plates having a filter membrane stretched on the liquid collecting portion. In the membrane separation device formed by stacking, the membrane separation devices are arranged such that the directions of the grooves of the liquid collecting portions of the filter plates facing each other intersect each other.