JP2012148218A - Leakage inspection method for hollow fiber membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leakage inspection method for a hollow fiber membrane module with which the presence/absence of a leak defect can be surely inspected.SOLUTION: A leakage inspection method is provided for a hollow fiber membrane module including: a plurality of hollow fiber membranes, a tubular case which accommodates the hollow fiber membranes while fixing one terminal side or both terminal sides of each of the hollow fiber membranes, a permeation-side tube opening which is provided in a side face of the case and communicated with an outside space of the hollow fiber membranes, and a stock solution feed tube opening which is provided in an end face of the case and communicated with an inside space of the hollow fiber membranes at one terminal side or both terminal sides of the hollow fiber membranes. The leakage inspection method for the hollow fiber membrane module includes reducing pressure in the outside space of the hollow fiber membranes from the permeation-side tube opening, or pressurizing the inside space of the hollow fiber membranes from the stock-solution feed pipe opening.

Description

  The present invention relates to a leak inspection method for a hollow fiber membrane module.

Conventionally, for example, for hollow water and groundwater clarification, clarification of industrial water, drainage and sewage treatment, purification of water such as pretreatment of seawater desalination, hollow fiber-like formed with various polymer materials A hollow fiber membrane module in which a large number of porous membranes are incorporated is used.
When manufacturing such a hollow fiber membrane module, the hollow fiber membrane is damaged by pinholes, cracks, or the like, or due to a poor seal between the housing body and the hollow fiber membrane constituting the hollow fiber membrane module. Leakage may occur between the interior and the housing. If such a leakage defect exists even at one location, it does not function as a separation device, so it is necessary to reliably detect the presence or absence of the leakage defect.

As a method for detecting a leakage defect of this type of hollow fiber membrane module, for example, a method is disclosed in which gas is injected into the hollow fiber membrane from the permeate side pipe and the generation of bubbles is observed (Patent Document 1). .
The hollow fiber membrane module used in this method uses means for providing a transparent cap at the module end and supplying air to a pipe communicating with the hollow fiber membrane outer space on the permeate side of the hollow fiber membrane module. As a result, air is sent to the outside of the hollow fiber membrane, and the pressure inside the hollow fiber membrane is released, so that the pressure on the outside of the hollow fiber membrane is maintained higher than that on the inside of the hollow fiber membrane. Air bubbles (bubbles) leaking from the terminal can be visually detected through the treatment liquid and the transparent cap.

JP-A-62-140607

However, by adopting various treated water and water treatment methods in recent years, in submerged MBR (Membrane Separation Activated Sludge Method), etc., in order to prevent a decrease in filtration efficiency due to the accumulation of dirt on the outer surface of the membrane. Pressurization is performed at various pressures on the inside and outside of the hollow fiber membrane, such as cleaning of the membrane surface with air, backwashing in an internal pressure type (external tank type) MBR or the like. Therefore, it is necessary to reliably eliminate leakage defects in any use or cleaning under pressure.
This invention is made | formed in view of the said subject, and it aims at providing the leak test | inspection method of the hollow fiber membrane module which can test | inspect the presence or absence of a leak defect reliably.

  The inventors of the present invention have conducted intensive research on the efficient use and maintenance of various types of hollow fiber membrane modules in recent years and their methods of use, and as a result, in the conventional hollow fiber membrane modules. In the inspection method for the presence or absence of leakage defects, it was found that the inspection for the presence or absence of reliable leakage defects was not necessarily performed. Depending on the form of breakage or blockage of the membrane, there is no leak when pressurized from the outside of the hollow fiber membrane on the permeate side, and the reverse operation may cause a leak, that is, the leak of the hollow fiber membrane. As a result, the present invention has been completed.

  According to the present invention, it is possible to reliably inspect whether there is a leakage defect regardless of the usage form of the hollow fiber membrane module.

It is a schematic sectional drawing of the hollow fiber membrane module which is a test object of the leak inspection method of the hollow fiber membrane module of this invention. In a hollow fiber membrane module, it is a schematic sectional drawing of the hollow fiber membrane module for demonstrating the leak test | inspection method of this invention which decompresses the hollow fiber membrane outer space from the permeation | transmission side pipe port. In a hollow fiber membrane module, it is a schematic sectional drawing of the hollow fiber membrane module for demonstrating the leak test | inspection method of this invention which pressurizes hollow fiber membrane inner space from a stock solution supply pipe port. It is a schematic sectional drawing of the hollow fiber membrane module for demonstrating the effect | action by the leak test | inspection method of the hollow fiber membrane module of this invention.

In the leak inspection method for a hollow fiber membrane module of the present invention, for example, as shown in FIG. 1, as a hollow fiber membrane module 1 to be inspected, at least a plurality of hollow fiber membranes 2, a cylindrical case 10 and Are provided.
As the hollow fiber membrane 2, any conventionally known one can be used, and the material, hollow fiber inner and outer diameters, lengths, numbers, and the like depend on the characteristics of the hollow fiber module to be obtained. It can be adjusted appropriately.

The cylindrical case 10 stores a plurality of hollow fiber membranes 2. The cylindrical case 10 can be made of various materials such as metals and plastics. Generally, plastic that can be easily molded and can ensure mechanical strength is used. Examples of the plastic used include acrylic resin, polystyrene resin, ABS resin, AS resin, and polycarbonate resin.
Preferably, a predetermined number of hollow fiber membranes 2 are bundled into a hollow fiber membrane bundle, and the hollow fiber membrane bundle is cut into a predetermined length in accordance with the cylindrical case 10 and inserted into the case. The state of the hollow fiber membrane bundle may be any state such as straight or U-shaped.
The plurality of hollow fiber membranes 2 are sealed in the case 10 at both end surfaces 10 a, 10 b side through a sealing material 11. This seal can be formed by, for example, potting by centrifugal molding. The seal material is preferably made of a material that has an initial viscosity, cures with time, and finally reaches a predetermined hardness, such as an epoxy resin or a urethane resin.
On the case side surfaces 10a and 10b between the seals 11, at least two permeate side pipe ports 12 to which permeate side conduits (not shown) communicating with the outer space of the hollow fiber membrane 2 are connected are arranged. Further, in the case 10, a stock solution supply line (communication with the inner (hollow) space) of the above-described plurality of hollow fiber membranes 2 on the end face (one end face or both end faces) 10 a, 10 b side from the seal material 11 ( The undiluted solution supply pipe port 13 is connected.
Such a hollow fiber membrane module itself has been conventionally known. For example, various modules described in JP-A Nos. 62-140607 and 2009-183822 described above may be used. it can.

  In such a leak testing method for the hollow fiber membrane module 1, (1) whether the hollow fiber membrane outer space is depressurized from the permeate side tube port, or (2) the hollow fiber membrane inner space is pressurized from the stock solution supply port Do one of the following.

(1) Depressurization of the outer space of the hollow fiber membrane from the permeate side tube port The depressurization of the outer space of the hollow fiber membrane from the permeate side tube port was formed on the side surface of the case 10 in the hollow fiber membrane module 1 as shown in FIG. A suction pump (not shown) is connected to the permeate-side tube port 12 and suction is performed in the direction of arrow B using this suction pump. The hollow fiber membrane originally has a function of permeating water and an aqueous solution, but is a membrane that does not permeate gas. Therefore, the reduced pressure at this time is not particularly limited, but may be lower than the atmospheric pressure. However, if it is too low, the damaged part will be widened. For example, about 0.05 to 0.2 MPa is suitable.

  During decompression, it is suitable that the liquid 14 is filled from the permeate-side tube port of the hollow fiber module 1 so that the entire outer side of the hollow fiber membrane 2 of the hollow fiber membrane module 1 is immersed in the liquid 14. ing. Further, at the time of this pressure reduction, it is suitable that the inner space of the hollow fiber membrane 2 is opened, that is, the state where the stock solution supply pipe port 13 is not closed, or the state where the stock solution is not supplied from the stock solution supply pipe. ing. As the liquid used here, tap water, pure water, or a solution obtained by dissolving a surfactant, an amphiphilic solvent, or the like in water can be used, but it is water from the viewpoint of not contaminating the hollow fiber membrane module. It is preferable.

  By performing such decompression, as shown in FIG. 2, when there is a damaged portion A in the hollow fiber membrane 2, an arrow C is drawn from the stock solution supply pipe port 13 connected to the inner space of the hollow fiber membrane 2. Air is introduced in the direction, and bubbles 15 are generated in the liquid 14 from the portion A. Therefore, the presence / absence of the damaged portion can be detected based on the presence / absence of the bubble 15.

When air bubbles are detected in the liquid outside the hollow fiber membrane due to this reduced pressure, the method for identifying the damaged hollow fiber membrane is as follows. A method of sequentially closing the above is mentioned. Alternatively, both ends of the hollow fiber membrane may be closed simultaneously. At this time, the entire outer side of the hollow fiber membrane continues to be immersed in the liquid 14. Further, the decompressed state of the outer space of the hollow fiber membrane from the permeate side tube port is maintained.
The hollow fiber membrane may be blocked by any method as long as airtightness is ensured by simply capping the stock solution supply pipe port 13. The sequential closing of the other end includes a method of pressing the other end of the hollow fiber membrane with an appropriate member or a finger. Further, both ends may be simultaneously pressed with a member or a finger. Furthermore, it is preferable to perform sequential occlusion for each hollow fiber membrane, but it may be performed for a plurality of, for example, 3 bundles, 5 bundles, and 10 bundles.
In this way, when the other end face of the hollow fiber membrane is sequentially closed, when the specific hollow fiber membrane or bundle is closed, the air bubbles generated in the liquid outside the hollow fiber membrane are not generated. Or a bundle is found. Therefore, it is possible to specify that the specific hollow fiber membrane or bundle closed immediately before this is a hollow fiber membrane or bundle having breakage. When a bundle of hollow fiber membranes is found, the hollow fiber membranes in which bubbles are not generated can be identified by sequentially closing the hollow fiber membranes one by one again.

  Another method for identifying a broken hollow fiber membrane is to sequentially close the end surface of the hollow fiber membrane at the other end while closing one end side of the hollow fiber membrane. There is a method of observing whether or not there is a pressure drop in the outer space of the hollow fiber membrane, instead of observing the presence or absence. In this case, the entire outer side of the hollow fiber membrane of the hollow fiber membrane module may be immersed in the liquid or may not be immersed in the liquid. However, it is suitable to maintain the decompressed state of the outer space of the hollow fiber membrane from the permeate side tube port. The presence or absence of this pressure drop can be detected by, for example, disposing a pressure gauge on the suction pump in order to maintain a reduced pressure state, or providing a separate pressure measuring means.

(2) Pressurizing the inner space of the hollow fiber membrane from the stock solution supply pipe port Pressurizing the inner space of the hollow fiber membrane from the feed port of the stock solution, as shown in FIG. The one end side of the liquid, ie, one end side of the stock solution supply pipe port 13 is closed, and the other end of the hollow fiber membrane 2 end face (stock solution supply pipe port 13) is filled with a gas pump such as a pressure pump or nitrogen gas (not shown). Can be performed by feeding air in the direction of arrow D using a gas pump such as this pressure pump or nitrogen gas. The pressurization at this time may be higher than the atmospheric pressure, but if it is too high, the damaged part is expanded, and for example, about 0.105 to 0.3 MPa is mentioned.

At the time of this pressurization, as described above, the hollow fiber module 1 is filled with the liquid 14 so that the entire outer side of the hollow fiber membrane 2 of the hollow fiber membrane module 1 is immersed in the liquid 14; It is suitable to do.
By performing such pressurization, when there is a damaged portion A in the hollow fiber membrane 2, air flows out in the direction of arrow E from the permeate side port 12 connected to the outer space of the hollow fiber membrane 2. , Bubbles 15 are generated in the liquid 14 from the portion A. Therefore, the presence / absence of the damaged portion can be detected based on the presence / absence of the bubble 15.

When air bubbles are detected in the liquid outside the hollow fiber membrane due to this pressurization, a method for identifying the damaged hollow fiber membrane is as follows. A method of pressurizing the inner space of the hollow fiber membrane sequentially from the end face is mentioned. At this time, the entire outer side of the hollow fiber membrane of the hollow fiber membrane module may be immersed in the liquid or may not be immersed in the liquid.
When the other end face of the hollow fiber membrane is sequentially closed in this way, an increase in pressure in the outer space of the hollow fiber membrane is found when a specific hollow fiber membrane or bundle is closed. Therefore, it is possible to specify that the blocked specific hollow fiber membrane or bundle is a hollow fiber membrane or bundle having a breakage. When a bundle of hollow fiber membranes is found, the hollow fiber membranes in which the pressure does not increase can be identified by sequentially closing the hollow fiber membranes of the bundle one by one again. The presence or absence of this pressure increase can be detected, for example, by using an output of a pressurizing pump to maintain a pressurized state, or by providing a separate pressure measuring means.

In addition, before or after performing either (1) depressurizing the hollow fiber membrane outer space from the permeate side tube port or (2) pressurizing the hollow fiber membrane inner space from the stock solution supply tube port, It is preferable to perform the step of 3) pressurizing the outer space of the hollow fiber membrane from the permeate side tube port, or (4) depressurizing the inner space of the hollow fiber membrane from the stock solution supply tube port.
In this case, as a method of pressurizing the outer space of the hollow fiber membrane from the permeate side tube port, the method described in JP-A-62-2140607 described above can be used. Specifically, there is a method in which the stock solution is supplied from the stock solution supply pipe port, the hollow fiber membrane inner space is filled with the liquid, and air is fed from the permeate side pipe port.
In addition, the method of decompressing the hollow fiber membrane inner space from the stock solution supply pipe port supplies the stock solution from the stock solution supply pipe port to fill the hollow fiber membrane inner space with liquid, while sending air from the permeate side tube port ( And a method of reducing the pressure from the stock solution supply pipe port.

In the leak inspection of the present invention, the step (1) or (2) described above and the step (3) or (4) performed before and after the step may be performed only once, or may be performed alternately a plurality of times. . For example, (1) + (3), (1) + (4), (2) + (3), (2) + (4) and the reverse order, (1) + (3) + (2), ( 1) + (4) + (1), (2) + (3) + (1), (2) + (4) + (1), (1) + (3) + (1), etc. . By such a plurality of operations, the hollow fiber membrane in which the leak has occurred can be detected more accurately.
In any of the inspection methods, the inspection method of the present invention may use the air atmosphere as it is in order to realize the decompression and pressurization states, but by using sterilized air, it becomes cleaner and Leak detection can be realized without contaminating the inside and outside of the hollow fiber membrane and the inside of the hollow fiber membrane module.

  In the above-described present invention, as conventionally employed, in the hollow fiber membrane module, in the pressurization from the outside of the hollow fiber membrane on the permeate side, for example, as shown in FIG. When the pressure M is applied to the outside of the tube 20, the fracture surface of the hollow fiber membrane 20 is closed. As a result, when the pressure is applied from the outside of the hollow fiber membrane 20, the gas flow s does not enter the hollow fiber membrane 20. In some cases, the hollow fiber membrane 20 may not be detected as a leak despite being broken. Further, as shown in FIG. 4C, when the foreign matter 21 is clogged in the broken portion of the hollow fiber membrane 20, even if the outer side of the hollow fiber membrane 20 is pressurized, the force causes the foreign matter 21 to pass through the hollow fiber. The pressure L is pushed into the ruptured portion of the membrane 20 to close the ruptured portion. Eventually, when the pressure is applied from the outside of the hollow fiber membrane 20, the gas flow r does not enter the hollow fiber membrane 20, and the hollow fiber membrane 20 Even though there is a rupture, it may not be detected as a leak.

  On the other hand, by performing the above-described method (1) or (2) according to the leak detection method of the present invention, the hollow fiber membrane outside on the permeate side in the hollow fiber membrane module is decompressed, for example, FIG. As shown in (b), when a pressure N is applied to the outside of the hollow fiber membrane 20, the fracture surface of the hollow fiber membrane 20 is opened, and as a result, the gas flow t flows from the inside of the hollow fiber membrane 20. The breakage of the hollow fiber membrane 20 is easily and reliably detected as a leak. In addition, as shown in FIG. 4 (d), even when the foreign matter 21 is clogged in the fractured portion of the hollow fiber membrane 20, the pressure is reduced on the outside of the hollow fiber membrane so The pressure K is pushed out from the breakage point, and the breakage point is opened. As a result, the gas flow w is generated from the inside of the hollow fiber membrane 20, and the breakage of the hollow fiber membrane 20 can be detected.

  Hereinafter, the leak inspection method of the hollow fiber membrane module of the present invention will be described in detail based on examples. In addition, this invention is not limited only to these Examples.

The hollow fiber membrane module shown in FIG. 1 was used as the hollow fiber membrane module used in the leak inspection method for the hollow fiber membrane module.
A predetermined number of hollow fiber membranes 2 are bundled as a hollow fiber membrane bundle, cut into a predetermined length, and inserted into the case 10. The plurality of hollow fiber membranes 2 are sealed in the case 10 at both end surfaces 10a and 10b via a sealing material 11, for example, an epoxy resin.
The cylindrical case 10 is made of, for example, a plastic made of acrylic resin, and a transmission side pipe line (not shown) communicating with the outer space of the hollow fiber membrane 2 is connected to the case side surfaces 10 a and 10 b between the seals 11. Two permeation-side tube ports 12 are arranged. Further, in the case 10, a stock solution supply line (not shown) that communicates with the inner (hollow) space of the hollow fiber membrane 2 described above on the end face (one end face or both end faces) 10 a, 10 b side from the sealing material 11. ) Is connected to the stock solution supply pipe port 13.
Although not shown, the permeation side pipe line connected to the permeation side pipe port 12 of the case side surfaces 10a and 10b is connected to a suction pump through a pipe line switching valve.

  For the above-described hollow fiber membrane module, after filling the hollow fiber membrane 12 with the liquid from the stock solution supply port 13 by the method described in the prior art, air is sent from the permeate side tube port 12 to check for leaks. Detected. And the following leak test was done with respect to the hollow fiber membrane module in which the leak of the air resulting from a leak is not observed.

First, a vacuum of 0.1 MPa was applied to the hollow fiber membrane module by a suction pump connected to the permeate side tube port 12.
However, the pressure in the hollow fiber membrane module could be reduced only by about 0.08 MPa.
As a result, the hollow fiber membrane is actually damaged, air flows in from the end of the hollow fiber membrane that is opened to the air, air flows in through the damaged portion of the hollow fiber membrane, It was observed that no vacuum was applied.

Thus, with respect to the hollow fiber membrane module in which leakage of the hollow fiber membrane was observed, one end of the hollow fiber membrane was closed, the hollow fiber membranes at the other end were pressed one by one, and the end surface was closed.
At this time, at the moment when one specific hollow fiber membrane was plugged, the pressure in the hollow fiber membrane module was measured to be 0.1 MPa, and a hollow fiber membrane in which the inflow of air stopped was found.
Then, the inside of the hollow fiber membrane where the leak was found was closed with an adhesive and cured.
When a leak test similar to the above was performed again, no air leak was observed.

From the above results, by changing the direction of pressurization for the hollow fiber membrane module, in which leakage was not observed in the conventional pressurization from the external pressure to the internal pressure due to the damaged shape of the membrane, Damage can be reliably detected.
In addition, it is possible to generate air leakage from the hollow fiber membrane only by attaching a suction type pump or a pipe switching valve without requiring a conventional large piping system that realizes external pressure pressurization.
Further, the leaked hollow fiber membrane is leaked by stopping the leak by a simple operation of sequentially closing one end of the hollow fiber membrane in a state in which the leak is generated using the reduced pressure on the outer space side of the hollow fiber membrane. Can be specified easily and in a short time.

  The present invention is used for water purification of river water and groundwater, clarification of industrial water, drainage and sewage treatment, pretreatment for seawater desalination, etc. It can be widely used as a water treatment membrane, a microfiltration membrane or the like.

DESCRIPTION OF SYMBOLS 1 Hollow fiber membrane module 2, 20 Hollow fiber membrane 10 Case 10a, 10b End surface 11 Sealing material 12 Permeation side tube port 13 Stock solution supply tube port 14 Liquid 15 Air bubble 21 Foreign material

Claims (7)

A plurality of hollow fiber membranes;
A cylindrical case for fixing and housing one end or both ends of the hollow fiber membrane;
A permeate-side tube port provided on a side surface of the case and in communication with the outer space of the hollow fiber membrane;
A leak inspection method for a hollow fiber membrane module provided on the end surface of the case, comprising a stock solution supply pipe port communicating with the hollow fiber membrane inner space at one or both ends of the hollow fiber membrane,
A leak inspection method for a hollow fiber membrane module, wherein the hollow fiber membrane outer space is depressurized from the permeate side tube port, or the hollow fiber membrane inner space is pressurized from the stock solution supply tube port.   The inspection method according to claim 1, wherein the hollow fiber membrane outer space of the hollow fiber membrane module is immersed in a liquid and the hollow fiber membrane outer space is depressurized from the permeate side tube opening in a state where the hollow fiber membrane inner space is opened. When bubbles are detected in the liquid outside the hollow fiber membrane due to the decompression of the outer space of the hollow fiber membrane,
With the one end side of the hollow fiber membrane closed, the other end of the hollow fiber membrane end surface is sequentially closed, and the occurrence / non-occurrence of liquid bubbles outside the hollow fiber membrane corresponding to the sequential blockage is inspected. The inspection method according to claim 2, further comprising: When bubbles are detected in the liquid outside the hollow fiber membrane due to the decompression of the outer space of the hollow fiber membrane,
In the state where one end side of the hollow fiber membrane is closed with or without immersing the entire outer side of the hollow fiber membrane of the hollow fiber membrane module, the other end of the hollow fiber membrane is sequentially closed, The inspection method according to claim 2, further comprising inspecting whether or not there is a pressure drop in the outer space of the hollow fiber membrane according to the sequential blockage.   Filling the hollow fiber membrane outer space of the hollow fiber membrane module with liquid, closing one end side of the hollow fiber membrane, pressurizing the hollow fiber membrane inner space sequentially from the end surface of the other end of the hollow fiber membrane, The inspection method according to claim 1, comprising inspecting generation / non-generation of liquid bubbles in the outer space of the hollow fiber membrane in response to pressurization. When bubbles are detected in the liquid outside the hollow fiber membrane due to pressurization of the outer space of the hollow fiber membrane,
The inner space of the hollow fiber membrane is sequentially inserted from the end surface of the other end of the hollow fiber membrane in a state where one end side of the hollow fiber membrane is closed with or without immersing the entire outer side of the hollow fiber membrane of the hollow fiber membrane module. The method according to claim 5, further comprising inspecting the presence or absence of a pressure drop in the outer space of the hollow fiber membrane according to the sequential pressurization.   The hollow according to any one of claims 1 to 6, further comprising pressurizing the outer space of the hollow fiber membrane from the permeate side tube port, or depressurizing the inner space of the hollow fiber membrane from the stock solution supply tube port. Yarn membrane module leak inspection method.

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