JP2945773B2 - Cross flow filtration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cross-flow filtration method.

[0002]

2. Description of the Related Art As a type of cross-flow filtration method, a fixed amount of undiluted solution stored in a undiluted solution tank is circulated and supplied into a filter by a circulating pump, and is placed on a filter membrane side of a filter stored in the filter. There is a cross-flow filtration method in which the undiluted solution is caused to flow along the filtration membrane from the negative side to the other side by the pressure difference on both sides of the filtration membrane. Specifically, any one of the cross-flow filtration methods shown in FIG. 2A or 2B is employed. In the first cross-flow filtration method shown in FIG.
A circulation path for circulating and supplying the undiluted solution contained in the undiluted solution tank 11 to the filter 12 is constituted by a path 14 in which the undiluted solution tank 11, the circulation pump 13 and the filter 12 are connected in series. In the second cross-flow filtration method shown in FIG. 2B, the circulation path is constituted by a path 15 that connects the circulation pump 13 and the filter 12 in series on the downstream side of the stock solution tank 11. I have.

[0003]

Incidentally, the cross-flow filtration method of this type is a batch method, in which a fixed amount of the stock solution stored in the stock solution tank 11 is treated to the maximum extent to minimize the remaining solution amount. Is preferred. However, when the first crossflow filtration method described above is adopted,
When the amount of the stock solution in the stock solution tank 11 decreases, the circulation pump 13
Entrains air together with the stock solution, and the operation of the circulating pump 13 is regulated, so that the stock solution cannot be circulated and supplied to the filter 12. Therefore, in the cross-flow filtration method,
There is a problem that the remaining amount of the stock solution is inevitably increased.

On the other hand, in the above-mentioned second cross-flow filtration method, only the amount of the circulating stock solution that is filtered and discharged from the stock solution tank 11 into the circulation path 15 is gradually supplied. The path 15 is shorter than the circulation path 14 of the first cross-flow filtration method,
5 has a small amount of undiluted solution, the circulation pump 13
The amount of undiluted solution that leads to air entrapment is small. However, in the cross-flow filtration method of this type, the concentration of the substance to be separated (hereinafter, referred to as a substance to be separated) mixed or dissolved in the circulating stock solution increases with time.
When the circulation path 15 is short and the stock solution holding amount is small as in the cross-flow filtration method of the above, the concentration of the substance to be separated in the circulating stock solution becomes high in a short time, and the filtration treatment time for a certain amount of the stock solution becomes the first filtration time. There is a problem that it takes a long time compared to the method.

[0005] Accordingly, an object of the present invention is to eliminate both of the above disadvantages in both of these cross-flow filtration methods.

[0006]

According to the present invention, there is provided a cross-flow filtration method of the type described above, wherein a first circulation path comprising a series connection of the stock solution tank, the circulation pump and the filter is provided. A second circulation path which connects the upstream side and the downstream side of the stock solution tank in the one circulation path to each other, and the circulation pump and the filter are connected in series; A predetermined amount is circulated and supplied to the filter through the first circulation path, and then circulated and supplied through the second circulation path.

[0007]

In the cross-flow filtration method according to the present invention, a first circulation path via the stock tank with a large amount of stock solution and a second circulation path through the stock solution with a small stock volume are used. When a large amount of undiluted solution is present, a large amount of undiluted solution is filtered using the first circulation path in a state where the concentration of the substance to be separated in the undiluted solution is low, and the remaining amount of undiluted solution is reduced. When there is a possibility that the circulation pump entrains air, the circulation supply of the stock solution is switched to the second circulation path. For this reason, during processing of a large amount of undiluted solution, the concentration of the substance to be separated in the undiluted solution is low, and a large amount of undiluted solution can be filtered without being greatly affected by the concentration. Can be shortened. In addition, since the undiluted solution is circulated and supplied using the second circulation route, the remaining amount of undiluted undiluted solution can be reduced. In this case, naturally, the undiluted solution having a high concentration of the substance to be separated is used. Is filtered, but since the amount of the stock solution is very small in quantity, there is almost no effect on the overall filtration time.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Filtration Apparatus FIG. 1 shows a filtration apparatus used in an embodiment of the present invention. The filtration device includes a stock solution tank 21, a filter 22, and a circulation pump 23 as main components.
A first circulation path 24 (hereinafter, referred to as a first circulation path) is formed by connecting the circulation pump 23 and the filter 22 in series, and the upstream and downstream of the stock solution tank 11 in the first circulation path 24. A second circulation path 25 (second circulation path) is formed by connecting the connection pipe line connecting the sides, the circulation pump 23 and the filter 22 in series.
An open / close valve, a flow control valve, and the like are interposed in both circulation paths 24, 25.

A water cooler 21 is provided in the stock solution tank 21.
a, and a water cooler 26 is interposed in the second circulation path 25. A monolithic filter 22a made of ceramic is provided in the filter 22. The filter 22a has a large number of through holes and a filtration membrane of a predetermined thickness on the inner periphery of each through hole. The circulating stock solution flows through each through hole along the-side of the filtration membrane.
During this time, the part of the undiluted solution permeates through the filtration membrane due to the pressure difference between the two sides of the filtration membrane, flows inside the wall of the filter 22a, and flows out of the filter 22 as a permeate (treatment liquid).

In such a filtration device, the first circulation path 2
4 circulates and supplies the undiluted solution stored in the undiluted solution tank 21 to the filter 22 by the operation of the circulating pump 23, and the second circulating path 25 removes the undiluted solution held in the circulating path 25 from the undiluted solution tank The liquid is circulated and supplied to the filter 22 together with the undiluted liquid corresponding to the permeated liquid supplied sequentially from 21.

(Experimental Example 1) A polyacrylate emulsion-containing solution containing 1% by weight of a polyacrylate in the form of an emulsion was used as a stock solution, and filtered under the following conditions to concentrate 150 liters of the stock solution 30-fold. An experiment (removal of polyacrylate) was performed by the method of the present invention and the method of the comparative example. The embodiment method is a method using the first circulation path 24 and the second circulation path 25, and the comparative example method is a method using only the second circulation path 25. Tables 1 and 2 show the filtration amount, concentration ratio, and filtration time of the stock solutions obtained by the method of the example and the comparative example. Filter: Ceramic monolithic filter, 4mm in diameter
With a pore diameter of 0.1 μm, a length of 1000 mm, and a filtration area of 0.24 m ² . Stock solution holding amount: minimum holding amount 15 in the first circulation path (24)
l, 5 l held in the second circulation path (25). Use of first circulation path (24): first open / close valve 26a is opened, and second open / close valve 26b is closed. Using the second circulation path (25): the first opening / closing valve 26a is closed, and the second opening / closing valve 26b is opened. Circulation flow rate: 4 m / sec. Filtration pressure: 3 kg / cm ² G. Temperature: 30
° C.

[0012]

[Table 1]

[Table 2]

(Experimental Example 2) An experiment in which a solution in which a protein for food additives is dissolved is used as a stock solution, and the solution is filtered under the following conditions to concentrate a 50-liter stock solution 10-fold (insoluble protein and polymer substances). Removal) was carried out by the method of Example and the method of Comparative Example. The embodiment method is a method using the first circulation path 24 and the second circulation path 25, and the comparative example method is a method using only the second circulation path 25. Tables 3 and 4 show the amount of filtration, the concentration ratio, and the filtration time of the stock solutions obtained by the method of the example and the comparative example. Filter: Ceramic monolithic filter, 4mm in diameter
Pore diameter and length of 150,000 with molecular weight cut off of 150,000
1000 mm, that of the filtration area 0.24 m ^2. Stock solution holding amount: minimum holding amount 15 in the first circulation path (24)
l, 5 l held in the second circulation path (25). Use of first circulation path (24): first open / close valve 26a is opened, and second open / close valve 26b is closed. Using the second circulation path (25): the first opening / closing valve 26a is closed, and the second opening / closing valve 26b is opened. Circulation flow rate: 3 m / sec. Filtration pressure: 2 kg / cm ² G. Temperature: 60
° C.

[0014]

[Table 3]

[Table 4]

(Consideration) As is clear from Tables 1 and 2, when a fixed amount of the undiluted solution is subjected to the filtration treatment in Experimental Example 1, the filtration time is remarkably reduced by employing the method of the embodiment as compared with the method of the comparative example. It can be shortened and the average flux in the example method is 239.3 l / m ² hr, while the flux in the comparative example method is 85 l / m ² hr. Further, as is clear from Tables 3 and 4, this tendency is the same in Experimental Example 2. In Experimental Example 2, the amount of the stock solution used was smaller than that in Experiment 1, so that a remarkable effect was obtained as in Experiment 1. Not out. This means that in the present invention, the larger the amount of the stock solution to be treated, the more remarkable its effect is, and the more advantageous it is as a filtration treatment. Mao, the average flux of Example methods in Experiment 2 was 26l / m ² hr, the and Comparative Examples method was 14l / m ² hr.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a filtration device used for performing a cross-flow filtration method according to the present invention.

FIG. 2 is a schematic configuration diagram showing a filtration device used for performing a conventional cross-flow filtration method.

[Explanation of symbols]

11, 21 ... undiluted solution tank, 12, 22 ... filter, 22a
… Filters, 13 and 23 circulating pumps, 14 and 15 circulating paths, 24… first circulating paths, 25… second circulating paths.

Claims (1)

(57) [Claims] 1. A fixed amount of undiluted solution contained in a stock solution tank is circulated and supplied into a filter by a circulation pump to flow along a filter membrane side of a filter housed in the filter. In the cross-flow filtration method in which the permeation from the negative side of the filtration membrane to the other side is filtered by the pressure difference between the two sides of the filtration membrane, and the stock solution tank, the circulation pump and the filter are connected in series. A first circulation path, a connection pipe line for connecting the upstream side and the downstream side of the stock solution tank in the first circulation path to each other, and a second line formed by connecting the circulation pump and the filter in series. A cross flow filtration method comprising forming a circulation path, circulating and supplying a predetermined amount of the stock solution to the filter through the first circulation path, and then circulating and supplying the undiluted liquid through the second circulation path.