JPH0513389Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a membrane separation device.

As a filtration device, a filter unit is housed in a stock solution tank with an opening at the top, the inside of this filter unit is communicated with a vacuum pump, the stock solution tank is filled with the stock solution, and the pressure inside the filter unit is reduced by driving the vacuum pump. A pressurized backwashing method is known in which the solvent in the stock solution permeates through the filter unit, and the permeation flow rate decreases due to the adhesion of solids in the stock solution to the surface of the filter unit (Japanese Patent Application Laid-Open No. 1983-1999).
Publication No. 1271).

By the way, if a flat permeable membrane envelope is used as the above-mentioned filter unit, the membrane separation can be performed with a sufficient membrane area while ensuring a passage for the stock solution by arranging the envelopes at a distance from each other.

However, although the permeable membrane envelope can withstand pressure from the outside to the inside,
Since it is an envelope, it is weak against pressure from the inside to the outside, and cannot withstand the pressure backwashing described above.

Therefore, even if the above-mentioned filtration device is used as a filter unit, it is difficult to perform satisfactory membrane separation.

The membrane separation device of the present invention has been devised in view of the above points, and includes a plurality of permeable membrane envelopes arranged at intervals from each other in the upper end opening or in a tank in which the opening is covered with a lid. This configuration is characterized in that a permeate suction pump is connected to these permeable membrane envelopes, and the tank is provided with a stock solution circulating means for flowing the stock solution onto the surface of the above-mentioned permeable membrane envelopes at high speed.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a tank with an open top. 2
1 is a permeable membrane cell supported in a tank (the supporting member is not shown), and a plurality of permeable membrane envelopes 21 are erected at intervals from each other. This permeable membrane envelope body 21 includes two flat membranes 22, 22 (usually an ultrafiltration membrane) as shown in FIGS. 2A and 2B (BB sectional view of FIG. 2A). A permeate spacer 23 (for example, plastic net) may be interposed between the flat membranes (used), and the periphery between the flat membranes may be sealed with a water-impermeable sealing material 24.

In FIG. 1, 3 is a permeate suction pump, and its suction side is connected to the permeate membrane cell 2 through a permeate pipe 4. 5 is a stock solution supply pipe, and 6 is a stock solution feed pump. l indicates the liquid level in the tank.
7 is a concentrate outlet provided in the tank 1, and 8 is a concentrate outlet pipe. 9 is a liquid circulation pump connected to tank 1;
10 is a liquid circulation pipe, and 11 is a nozzle pipe having jet nozzles 12, 12, . . . at regular intervals.

Due to the operation of the suction pump 3, the inside of the permeable membrane cell 2 becomes negative pressure, and a transmembrane pressure difference acts between the outside of the cell, that is, the stock solution side, and the inside of the cell, and the solvent in the stock solution is pumped inside the permeable membrane cell 2. It passes through.

To process the stock solution using the above membrane separator,
If the amount of permeated water is al/h, the amount of concentrated liquid taken out is bl/h, and the amount of raw solution supplied is cl/h, set each liquid amount so that c=a+b is satisfied and the concentration ratio is the desired value. Then, according to these setting conditions, the permeate suction pump 3
At the same time, the stock solution feed pump 6 may be operated. During the processing of this stock solution, the stock solution in the tank is circulated by the circulation pump 9.
Continuous stirring makes it possible to effectively prevent concentration polarization on the membrane surface. Furthermore, since the jetting flow of the stock solution from the nozzle pipe 11 is caused to flow at high speed on the membrane surface, the formation of a gel layer can be reduced, and membrane fouling can be alleviated.

Furthermore, if membrane fouling progresses and membrane surface cleaning becomes necessary, since the tank 1 is of an open type, the membrane can be taken out and cleaned easily.

In particular, as shown in FIG.
If a membrane brush 13 (for example, a sponge body) is provided between the chambers 1 and 14 so as to be movable vertically or horizontally using a support rod 14, cleaning can be performed while the membrane is supported in the tank.

In the above, the top opening of the tank can be covered with a lid. In this case, the tank does not need to be airtight, and a lid that can be easily attached and removed can be used, making it easy to take out the membrane for cleaning. .

As mentioned above, the membrane separator of the present invention has a structure in which a plurality of permeable membrane envelopes are provided at intervals from each other in a tank with an opening at the top end, and a permeate suction pump is connected to these permeable membrane envelopes. However, since a stock solution circulation means is provided to flow the stock solution at high speed on the surface of the permeable membrane envelope, concentration polarization and gel layer formation on the membrane surface can be effectively prevented, and unlike conventional methods, back pressure washing is possible. An excellent permeation flow rate can be guaranteed for a sufficiently long period of time without providing any means. In addition, for membrane cleaning,
The method of removing the permeable membrane envelope from the tank and cleaning the outer surface (or the method shown in Fig. 3) can be used, and the frequency of cleaning can be significantly reduced by reducing the concentration polarization and gel layer formation, and the tank is open at the top. Since the permeable membrane envelope can be easily taken out (or the brush 13 can be easily moved up and down), membrane cleaning can be performed very easily without back pressure cleaning.

Therefore, according to the present invention, by placing the filtration unit in a tank with an open top and reducing the pressure inside the filtration unit, it is possible to perform membrane separation favorably by using a permeable membrane envelope in the filtration unit.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the membrane separation device of the present invention, Fig. 2 A is a cross-sectional explanatory diagram showing an example of a permeable membrane body used in the present invention, and Fig. 2 B is a BB cross section in Fig. 2 A. The explanatory diagram and FIG. 3 are explanatory diagrams showing an example of a membrane wire cleaning means used in the apparatus of the present invention. In the figure, 1 is a tank, 2 is a permeation membrane cell, 3 is a permeate suction pump, 5 is a raw solution supply pipe, and 8 is a concentrate extraction pipe.

Claims (1)

[Scope of utility model registration request] A plurality of permeable membrane envelopes are provided at intervals from each other in the upper end opening or in a tank in which the opening is covered with a lid,
A membrane separation device characterized in that a permeate suction pump is connected to these permeable membrane envelopes, and a tank is provided with stock solution circulation means for flowing the stock solution onto the surface of the above-mentioned permeable membrane envelopes at high speed.