JPH0994441A - Membrane separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane separator without using a large-sized pump or a diffuser pipe, compressor, etc., at the time of dipping a membrane element formed by laminating a bag-shaped flat membrane in a raw liq. tank to conduct filtration and separation, with the entire separator miniaturized and capable of efficiently preventing the formation of a cake bed on the membrane face. SOLUTION: A membrane element A formed by laminating a bag-shaped flat membrane 10 through a spacer 2 for a raw liq. passage is placed in a raw liq. tank 4, presser bars 51, 52 and 53 are abutted on both sides of the element to bend the laminate of the bag-shaped membranes, and a means for reciprocating the presser bar groups is furnished over both ends of the laminate. Otherwise, the presser bar groups are fixed, and a means for reciprocating the laminate is furnished instead of the presser bar reciprocating means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane separation device having a bag-shaped flat membrane laminate as a membrane element.

[0002]

2. Description of the Related Art When filtering and separating a highly turbid stock solution,
A membrane element made by stacking flat bag-shaped membranes is immersed in an open stock solution tank, the filtration side of this membrane element is depressurized to generate a transmembrane pressure difference, and the stock solution is pumped or aerated. It is known that filtration and separation are performed under the above-mentioned transmembrane pressure difference while flowing.

Conventionally, as a membrane element for liquid separation, a flexible spacer for a filtrate passage and a sheath for wrapping the spacer.
A plurality of bag-shaped flat membranes consisting of a bag-shaped separation membrane are stacked, and all the bag-shaped flat membranes are placed in one place by a mechanism that takes out the filtrate from the bag-shaped flat membranes in relation to each other. There is known a membrane set that is fixed to each other only in the above, and in other places, all the bag-shaped flat membranes move independently of each other in the entire bag-shaped flat membranes by the flow of the fluid (Patent Publication 7).
No. 22687), the flow of the undiluted solution by the pump is also used as the rocking source of each bag-shaped flat membrane in this membrane set. As is well known, the flow of the stock solution on the membrane surface and the fluctuation of the membrane suppress the deposition and adhesion of the solid matter in the stock solution on the membrane surface (that is, suppress the formation of the cake layer), and the filtration. It is indispensable for preventing a decrease in flux.

[0004]

However, in the prior art, the formation of the cake layer is suppressed by flowing the stock solution in the tank by means of a pump or an air diffuser,
Only the flux in contact with the film surface in the flux contributes to the suppression of the generation of the cake layer, and the energy efficiency is low. Thus, a pump or air diffuser and a compressor
Therefore, it is necessary to use such a large-sized device, which inevitably leads to an increase in equipment cost and an increase in installation space. In order to eliminate such inconvenience, it is conceivable to fix the above liquid separation membrane element at one end on the side where the filtrate is taken out, and forcibly swing the other end. It is difficult to sway the membrane satisfactorily, it is difficult to effectively oscillate the entire membrane element, and the reduction of the filtration flux due to the early generation of the cake layer in the membrane portion near the fixed end cannot be avoided.

An object of the present invention is to immerse a membrane element in which a bag-shaped flat membrane is laminated in a stock solution tank for filtration / separation without using a large pump, a diffuser pipe, a compressor, or the like. An object of the present invention is to provide a membrane separation device capable of efficiently preventing the formation of a cake layer on the membrane surface while sufficiently reducing the size of the entire device.

[0006]

Means for Solving the Problems In the membrane separation device according to the present invention, bag-shaped flat membranes having the inside thereof on the filtrate side are stacked via a spacer for a raw liquid passage to form a bag-shaped flat membrane. The filtrate outlet port provided at one end is connected, the membrane element from which the filtrate is taken out is stored in the stock solution tank, and the pressing rod group is abutted on both sides of the membrane element to form a bag shape. The flat membrane laminate is locally bent, and a holding rod moving means for reciprocating the holding rod group between both ends of the above-mentioned laminated body is provided. Can be fixedly installed, and a stack moving means for reciprocating the bag-shaped flat membrane stack can be provided instead of the presser bar moving means.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a plan explanatory view showing an example of the membrane element A used in the present invention, and FIG. 1B is a cross-sectional view taken along the line RO of FIG. In FIG. 1A and FIG. 1B, 1 is a laminated body of the bag-shaped flat membranes 10, 10 ,.
An undiluted solution passage is secured between 0 and 10 by interposing an undiluted solution passage spacer 2, for example, a mesh spacer. The bag-shaped flat membrane 10 has a spacer (for example, a plastic net, a plastic non-woven fabric, a tricot cloth, etc.) for the passage of a filtrate between two flat membranes (ultrafiltration membrane or microfiltration membrane). It is possible to use those whose periphery is sealed by heat fusion or an adhesive. Reference numeral 3 denotes a filtrate collecting pipe, and the collecting pipe 3 is penetrated into the filtrate extracting hole passages 11, 11 ... at one end side of each bag-shaped flat membrane 10, 10 ,. Of the filtrate passage (the passage secured by the spacer for the filtrate passage) communicates with the inside of the water collecting pipe 3 through the holes 31, ... This filtrate collection pipe 3
Has been penetrated.

FIG. 2A is a front explanatory view showing an example of the membrane separation device according to the present invention, and FIG. 2B is a side explanatory view of the same. In FIG. 2A and FIG. 2B, 4
Is an open stock solution tank. A is the above-mentioned membrane element, which is housed in the stock solution tank 4, and both ends thereof are retained in the stock solution tank 4 via appropriate clamp members 41 and 42. The lower end of the membrane element can also be free without being clamped. 51, 52 and 53 are presser bar groups each having a circular cross section, and 50 is a connecting member for the presser bar groups.
Thus, the bag-shaped flat membrane laminate is locally bent, and a linear portion is adjacent to this locally bent portion. The length of each of the laminated flat bag-shaped membranes in the membrane element A is set so as to correspond to such bending smoothly in (b) of FIG.
The length is made longer toward the arrow a side.

The holding rod group is capable of reciprocating between both ends of the laminated body. As the holding rod moving means, a holding rod group guide rail is provided on the inner surface of the tank wall of the stock solution tank. Use one that moves up and down along the rail by the vertical movement axis, or one that suspends and holds the presser bar group and moves it by pulling the suspension wire to the upper row and lowers it by the weight of the presser bar group in the lower row. However, the illustration is omitted. In the above-mentioned presser bar group, it is preferable that the vertical interval between the presser bar 51 and 52 is about 1/3 of the length of the membrane element A, and the presser bar 53 is located substantially in the center between the presser bar 51 and 52. . The lateral distance between the presser bar 51 and the presser bar 53 is
To prevent excessive resistance to the movement of the presser bar group,
It is set according to the vertical distance between the presser bars 51 and 53 and 53 and 52. The presser bar may be a freely rotating roll type. Also, the presser bar has a cylindrical body,
Any of tubular bodies may be used, and the material thereof is metal,
Plastic etc. can be used.

In order to separate the undiluted solution by the membrane separation device according to the present invention, as shown in FIG. 2, a suction pump is attached to the filtrate collecting pipe 3 attached to the membrane element A via a flexible hose 61. 62 is connected, and by driving the suction pump 62, a transmembrane pressure difference is generated in each bag-shaped flat membrane and the pressing rod group 51,
While moving 52 and 53 up and down over the entire length of the membrane element A, filtration and separation are advanced.

With the movement of the presser bar group, the membrane elements are bent one after another along the longitudinal direction, and each bag-shaped flat membrane 1
0 and relative space passage spacer 2 are moved relative to each other,
Also, as a result of the membranes on both sides of the membrane element being rubbed with the presser bar,
The solid content in the undiluted solution is prevented from depositing and adhering to the film surface, and the formation of the cake layer is suppressed. In the above, bag-shaped flat membranes having the same length are laminated on the membrane element, and one end of these laminated flat membranes is bound by the filtrate collecting pipe in the same manner as described above, and the other end is long. A hole may be provided and the other end of the laminated body may be connected by inserting a pin into the long hole.
In the membrane separation device according to the present invention, the pressing rod group may be fixedly installed, and instead of the pressing rod moving means, a laminate moving means for reciprocating the bag-shaped flat membrane laminate may be provided.

The operation method of the membrane separator is as follows:
_{When the} suction pump is driven under _{1 and} the filtration flux reaches the lower limit value J'due to the formation and progress of the cake layer on the membrane surface, the suction pump is stopped and the filtration flux is almost the initial value. The membrane is cleaned to the extent that it recovers to J, and the above is set as one cycle, and then repeated (constant pressure operation method), the filtration flux even if the formation of the cake layer on the membrane surface progresses. The decompression degree is increased with time so that the constant decompression degree becomes constant J _0, and when the decompression degree reaches a predetermined limit value p ′, the drive of the suction pump is stopped, and the constant filtration flux J ₀ is almost equal to the initial decompression degree. A method in which membrane cleaning is performed to the extent that can be obtained with p ₁ and the above is set as one cycle, and then repeated (constant filtration flux operation method)
However, in the operation of the membrane separation device according to the present invention, the membrane element is bent more violently when the suction pump is stopped, as compared with the bending of the membrane element during filtration / separation by driving the suction pump. It is also possible to clean the film by removing the cake layer by vigorous bending.

The membrane separation apparatus according to the present invention can also be carried out by a system in which a pressure-resistant closed tank is used as the stock solution tank and the pressure on the stock solution side is applied to generate a transmembrane pressure difference necessary for filtration. .

[0014]

In the membrane separation apparatus according to the present invention, since the bag-shaped flat membrane laminate is forcibly bent to rub the bag-shaped flat membranes against each other, the whole stock solution in the tank is pumped or The formation of a cake layer on the film surface can be well prevented and the energy consumption can be sufficiently reduced even without flowing with an air diffuser. Therefore, according to the present invention, without using a large pump or air diffuser and compressor,
The liquid can be filtered and separated by efficiently preventing the formation of the cake layer on the membrane surface under the sufficient miniaturization of the entire apparatus.

[Brief description of drawings]

1 (a) is an explanatory plan view showing a membrane element used in the present invention, and FIG. 1 (b) is FIG. 1 (a).
FIG. 4 is a cross-sectional explanatory view taken along line ‘

2 (a) is a front explanatory view showing a membrane separation device according to the present invention, and FIG. 2 (b) is a side explanatory view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated body 10 Bag-shaped flat membrane 11 Filtrate extraction hole 2 Spacer for stock solution passage 3 Filtrate collection pipe 4 Stock solution tank 51 Presser bar 52 Presser bar 53 Presser bar 62 Suction pump

Claims (2)

[Claims] 1. A bag-shaped flat membrane having the inside thereof as the filtrate side is laminated via a spacer for a raw solution passage, and a filtrate take-out hole provided at one end of each bag-shaped flat membrane is communicated. The membrane element from which the filtrate is taken out from the communication hole is housed in the stock solution tank, and the pressing rod group is brought into contact with both sides of the membrane element to locally bend the bag-shaped flat membrane laminate, A membrane separating device comprising a holding rod moving means for moving the holding rod group back and forth between both ends of the laminate. 2. The presser bar group according to claim 1, wherein the presser bar group is fixedly installed, and a laminate moving means for reciprocating the bag-shaped flat membrane laminate is provided in place of the presser rod moving means. Characteristic membrane separation device.