JP2006258764A - Leak inspection method for separation membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leak inspection method for separation membrane which can simply and inexpensively determine the existence of leak in a separation membrane and which can specify the leak part according to kinds of separation membranes. <P>SOLUTION: An inspection liquid containing a coloring material is supplied to the separation membrane, and the existence of the leak in the separation membrane is determined by the existence of the coloring of a permeation liquid permeating through the separation membrane. The permeation liquid is subjected to a filtering process using a filtration material to detect the existence of the leak in the separation membrane by the existence of the coloring of the filtration material. The leak part of the separation membrane is specified by a colored part of a joint part of the separation membrane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a leak inspection method capable of determining the presence or absence of a leak in a separation membrane, and further to a leak inspection method for a separation membrane capable of specifying a leak site.

  In recent years, separation membranes are often used for applications such as liquid and gas filtration, solid-liquid separation, substance concentration, microbial cell removal and concentration. There are various types of separation membranes, such as microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, and dialysis membranes, depending on the desired fractionation performance, and there are various forms such as flat membranes, hollow fiber membranes, and tubular membranes. is there. Such a separation membrane is rarely used only as a membrane, and is used as a separation membrane module, and quality inspection at the time of manufacture, inspection for the presence or absence of leakage before or during use, and the like are performed.

As such a leak inspection method, for example, a liquid containing turbidity or fine particles is supplied to the primary side of the separation membrane, and the turbidity of the permeate that has permeated the separation membrane or the number of particles in the permeate is measured. A method for determining the presence or absence of leakage in the separation membrane has been proposed (see Patent Document 1).
JP 2001-343320 A

  However, in the above inspection method, the average number of particles in the permeate is measured using a turbidimeter or a particle counter, and the presence or absence of leakage is determined based on this measurement. The inspection method is complicated and expensive. There is a problem of becoming. In addition, the above-described inspection method has a problem that the presence or absence of a leak can be determined, but the leak site cannot be specified.

  The present invention has been made in view of such a situation, and can easily and inexpensively determine the presence or absence of a leakage of a separation membrane, and also specifies a leakage site depending on the type of separation membrane. An object of the present invention is to provide a method for inspecting a separation membrane leak.

  In order to solve the above-described problems, the method for inspecting a leak of a separation membrane according to the present invention supplies a test solution containing a coloring substance to the separation membrane, and determines whether or not the permeated liquid that has permeated the separation membrane is colored. The presence or absence of a leak is determined (claim 1).

  According to the above invention (Invention 1), it is possible to determine the presence or absence of leakage of the separation membrane by a simple and low-cost method of determining the presence or absence of coloring of the permeated liquid that has passed through the separation membrane.

  In the above invention (Invention 1), the presence or absence of coloring of the permeate may be determined by filtering the permeate using a filter medium and determining whether or not the filter medium is colored (Invention 2), or In the case where the permeation liquid is colored or not is determined by visual permeation of the permeation liquid, and the permeation liquid cannot be confirmed visually, the permeate is further filtered using a filter medium, and the filter medium The presence or absence of coloring may determine the presence or absence of leakage in the separation membrane.

  According to the above inventions (inventions 2 and 3), even when the amount of leakage from the separation membrane is small, the presence or absence of leakage from the separation membrane can be determined easily and at low cost.

  In the above inventions (Inventions 1 to 3), when the separation membrane is a separation membrane having a junction, when it is determined that there is a leak with respect to the separation membrane, the coloring portion at the junction of the separation membrane It is preferable to specify the leak site of the separation membrane (claim 4).

  According to the said invention (invention 4), the leak site | part of a separation membrane can be specified by the simple method of confirming the coloring site | part in the junction part of a separation membrane.

  In the said invention (invention 1-4), it is preferable that the said coloring substance is a substance (invention 5) or a bengara (invention 6) which has a particle size larger than the pore diameter of a separation membrane.

  According to the present invention, it is possible to easily determine whether there is a leak in the separation membrane at low cost, and it is also possible to specify the leak site depending on the type of the separation membrane.

  Hereinafter, a leakage inspection method for a separation membrane according to an embodiment of the present invention will be described.

  The separation membrane to which the separation membrane leak inspection method according to this embodiment can be applied is not particularly limited. For example, the separation membrane can be applied to separation membranes such as microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, and dialysis membranes. Can do. Further, the form of the separation membrane is not particularly limited, and can be applied to a flat membrane, a hollow fiber membrane, a tubular membrane and the like. Among these various separation membranes, in particular, those having a joint portion can be performed up to the specification of a leak site in the joint portion. Therefore, in this embodiment, the separation membrane having a joint portion will be described as an example.

  As shown in FIG. 1, the separation membrane 1 to be subjected to a leak inspection in the present embodiment is formed into a bag shape by superposing two substantially rectangular membrane materials 2 and joining them at a joint 5 on three sides. It has a membrane member 3 and a core bar 4 to which one side of the membrane member 3 is connected, and a concentrated water outlet 6 is provided on the secondary side of the separation membrane 1.

  In the separation membrane leak inspection method according to this embodiment, as shown in FIG. 2, first, a test solution is prepared in a test solution preparation step (S1). The test solution is usually prepared by adding a coloring substance to water such as industrial water or tap water.

  The coloring material is not particularly limited as long as it can color the separation membrane 1 and the filter medium described later. For example, bengara (red iron oxide), black iron oxide, yellow iron oxide, or the like is used. In particular, it is preferable to use bengara which is excellent in colorability.

  The particle size of the coloring substance is preferably larger than the pore size of the separation membrane 1 (the membrane material 2) and the filter medium described later. When the particle size of the coloring substance is equal to or smaller than the pore size of the separation membrane 1 and the filter medium, the coloring substance does not remain in the separation membrane 1 or the filter medium, and it is determined whether there is a leak in the separation membrane 1 or specifies the leak portion. You may not be able to do it. Since the particle size distribution of Bengala is biased to 0.2 μm or more, by separating the Bengala into a particle size larger than the pore size of the separation membrane, the separation membrane 1 and the filter medium having a pore size of 0.2 μm or more can be obtained. It is possible to use.

  The concentration of the coloring substance in the test solution is not particularly limited as long as it is a concentration that can determine whether or not there is a leak and specify the leak site, but usually 0.02 to 0.1 g / L. It is preferable to set the degree.

Next, in the test liquid supply step (S2), the test liquid containing the coloring substance is supplied to the primary side of the separation membrane 1 (the side where the liquid to be processed is introduced when performing the separation membrane process). Although the supply amount of the test solution varies depending on the type of the separation membrane 1, it is usually preferable to supply about 100 to 1000 L / hr · m ² per unit area of the membrane material 2 of the separation membrane 1.

  Next, in the permeated liquid coloring inspection step (S3), the presence or absence of coloring of the permeated liquid that has passed through the separation membrane 1 in the inspection liquid supply step (S2) is visually inspected. If the permeated liquid is colored as a result of this inspection, it can be determined that there is a leak in the separation membrane 1. Usually, when the amount of leakage from the separation membrane 1 is large, the coloration of the permeate can be confirmed visually as described above. In this case, it is predicted that the separation membrane 1 has a large or many leakage portions. .

  On the other hand, as a result of the above inspection, when the coloration of the permeate cannot be visually confirmed, the permeate is filtered by the next filtration step (S4). By performing this filtration step (S4), it is possible to determine the presence or absence of leakage in the separation membrane 1 even when the amount of leakage from the separation membrane 1 is small.

  In the filtration step (S4), the permeate is subjected to filtration using a filter medium by a conventional method. For example, the filtration treatment can be performed by introducing the permeate into a filtration device and performing suction filtration. The filter medium used in the filtration step (S4) is not particularly limited as long as it has a pore size smaller than the particle size of the coloring substance and can be colored by the coloring substance. MF paper) or the like is preferably used. The color of the filter medium is preferably a color that can easily determine the presence or absence of coloring, and is particularly preferably white.

  In the filtration step (S4), for example, MF paper (pore diameter: 0.45 μm, material: cellulose acetate, color: white) is used as a filter medium, and 1 L of permeate is suction filtered at a pressure of 66.7 kPa (500 mmHg). Can be performed.

  After the filtration process is completed, in the filter medium coloring inspection step (S5), the filter medium used in the filtration step (S4) is inspected for coloring. When the filter medium is colored, it can be determined that a coloring substance is present in the permeate and the separation membrane 1 is leaked. When the filter medium is not colored, the permeate is colored. It can be determined that no substance is present and there is no leakage in the separation membrane 1.

  In addition, since the filtration time in a filtration process (S4) becomes slow compared with the case where a coloring substance does not exist when a coloring substance exists in a permeation | transmission liquid, the filtration time is measured. Accordingly, it is possible to determine whether or not the separation membrane 1 has leaked.

  If it is determined that there is a leak in the permeate coloring inspection step (S3) or the filter medium coloring inspection step (S5), the leak portion of the separation membrane 1 is specified by the leak portion specifying step (S6).

  In the leak site identification step (S6), as shown in FIG. 3, the junction 5 of the separation membrane 1 is peeled off, and the color site in the junction 5 is visually confirmed to identify the leak site 7. When the leak part 7 exists in the joint part 5 of the separation membrane 1, the inspection liquid containing the coloring substance enters the leak part 7 of the joint part 5 and the joint part 5 is colored. The leak site 7 can be identified by visually confirming the colored site of the part 5.

  By specifying the leak site 7 in this way, the cause of the leak can be estimated. For example, as shown in FIG. 3, when there is a leak site 7 in the junction 5 in the longitudinal direction of the separation membrane 1 (in the direction orthogonal to the core bar 4), the membrane material 2 during the separation membrane manufacturing process is joined. It can be presumed that this is due to the high pressure, and when there is a leak site 7 at the junction 5 in the lateral direction (parallel to the core bar 4) of the separation membrane 1, the membrane in the separation membrane manufacturing process It can be presumed that the cause is that the pressure at the time of joining the material 2 is low.

  Thus, according to the separation membrane leak inspection method according to the present embodiment, a test solution containing a coloring substance is supplied to the separation membrane, and the presence or absence of leakage of the separation membrane is determined depending on whether the permeate or the filter medium is colored. Since the inspection and the identification of the mark portion can be performed, the quality inspection of the separation membrane can be performed easily and at low cost.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, the permeated liquid coloring inspection step (S3) may be omitted, and the permeated liquid supplied to the separation membrane 1 and permeated through the separation membrane 1 in the inspection liquid supply step (S2) may be directly subjected to the filtration step (S4). .

  The present invention is useful for quality inspection of separation membranes such as microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, and dialysis membranes.

It is a perspective view which shows the separation membrane which can receive application of the leak test | inspection method of the separation membrane which concerns on this embodiment. It is a flowchart which shows the leak test method of the separation membrane which concerns on this embodiment. It is a conceptual diagram which shows the leak site | part identification method in the leak test method of the separation membrane which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Separation membrane 5 ... Junction part 7 ... Leak site

Claims (6)

  A separation membrane leak inspection method comprising: supplying a test solution containing a coloring substance to a separation membrane, and determining whether or not the separation membrane has leaked based on the presence or absence of coloring of the permeate that has permeated the separation membrane.   The separation membrane leakage inspection method according to claim 1, wherein the permeated liquid is colored or not by filtering the permeated liquid with a filter medium and judging whether or not the filter medium is colored. The presence or absence of coloration of the permeate is determined by the presence or absence of coloration of the permeate visually.
2. When the coloration of the permeate cannot be visually confirmed, the permeate is further filtered using a filter medium, and the presence or absence of leakage of the separation membrane is determined based on the color of the filter medium. 2. A method for inspecting a leakage of a separation membrane according to 1. The separation membrane is a separation membrane having a joint,
The separation membrane according to any one of claims 1 to 3, wherein when the separation membrane is judged to have a leak, the leakage portion of the separation membrane is specified by a colored portion at a junction of the separation membrane. Leak inspection method.   5. The separation membrane leak inspection method according to claim 1, wherein the coloring material is a material having a particle size larger than the pore size of the separation membrane. The method for inspecting a leakage of a separation membrane according to claim 1, wherein the coloring substance is bengara.

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