JPH05157654A - Leakage inspection method of film-separation device - Google Patents

Abstract

PURPOSE:To enable presence or absence of leakage defect of a film to be detected readily by filling a pressurized gas into one chamber which is isolated by a film, enclosing a liquid or a gas into the other chamber and at the same time providing a pressure-detection means, and then measuring pressure of a chamber at a side where gas leaks. CONSTITUTION:A stock solution inside a bundle 4 of a hollow yarn filtering film and upper and lower stock solution chambers 2 is delivered out of a system. Then, a valve 11 is closed and valves 13 and 14 are shielded while liquid is filled into a filtering liquid chamber 3. After that, a pressurized air is filled into a stock solution chamber 2 and the hollow yarn 4. On the other hand, a filtering liquid chamber 3 is in the same pressure as the pressurized air in liquid-sealing state. At this time, an air chamber 5 is shielded by a valve 12 and a normal-pressure air is filled inside. Then, the valve 12 is opened and a pressure of the liquid-filtering chamber 3 is reduced to a pressure which is lower than the pressurized air. At this time, when the filtering film is in a wet state, permeation of gas within a porous film is prevented extremely by surface tension, pressure increase at a liquid side of a sound film without any defect is slight, and the increase speed is calibrated previously. A pressure within the filtering liquid chamber 3 increases abnormally when there are defects.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Also, the present invention relates to a leak inspection method for promptly and surely detecting the presence or absence of a leak defect due to a poor seal between the main body and the film.

[0002]

2. Description of the Related Art Membrane separation devices incorporating filtration membranes such as ultrafiltration membranes and reverse osmosis membranes are widely used in fields such as wastewater treatment, pure water production, seawater desalination, and artificial kidney and plasma separation. Has been. These membrane separators are composed of a stock solution chamber and a filtrate chamber which are separated by a filtration membrane.

During the process of manufacturing or using such a membrane separator, the membrane is damaged by pinholes, cracks, etc., or due to a poor seal between the body of the apparatus and the membrane, the stock solution chamber and the filtrate separated by the membrane. May leak into the room. If such a leak defect exists even at one place, it does not function as a separation device, so it is necessary to reliably inspect for the presence of the leak defect.

Conventionally, as a method of detecting these leakage defects, (1) a method of detecting a pressure drop of a pressurized gas in a stock solution supply system (Japanese Patent Laid-Open No. 60-94105) (2) a gas in a hollow fiber membrane (3) a method of supplying a pressurized gas to the outer surface of the hollow fiber in a dry state to visually check the leaked gas (Japanese Patent Laid-Open No. 56-39921),
(4) Method for detecting changes in electrical conductivity
No. 107083).

[0005]

In the prior art, the method of detecting the pressure drop of the pressurized gas is such that the pressure of the pressurized gas can be detected even if there is no defect in the membrane separation device, or if there is a minute leak in the piping system. Is extremely sensitive to deterioration, so it cannot be distinguished from defects in the membrane separation device, and there are many detection errors. The method of injecting gas to see the generation of bubbles and the method of making leaked gas optical have a drawback that they cannot be applied when the exterior of the device is opaque. Further, in order to detect a change in electric conductivity, it is necessary to supply a fluid that changes the electric conductivity of the treated liquid as a stock solution, and a step of washing the stock solution again after the inspection is required. There was a problem such as.

An object of the present invention is to provide a leak inspection method for a membrane separation device capable of quickly and surely detecting the presence or absence of a leakage defect due to damage to the membrane, a defective seal with the main body or the like. To provide.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a membrane separation apparatus in which one chamber separated by a membrane is filled with a pressurized gas, and the other chamber is filled with a liquid or a gas and the pressure is increased. A leak inspection method for a membrane separation device, characterized by providing a means for detecting and measuring the pressure in a chamber on the side where gas leaks.

That is, for example, the stock solution chamber side (unprocessed solution side) separated by the membrane is filled with a gas such as pressurized air. On the other hand, when a liquid such as water is sealed in the filtrate chamber side (processed liquid side) to measure the pressure, a gas such as air is filled so that the filtrate chamber including the piping system is not completely liquid-sealed. An airtight gas chamber is connected to the filtrate chamber and a pressure gauge is provided in the filtrate chamber. By doing so, when the gas leaks from the defective portion to the filtrate chamber in which the liquid is sealed, an abnormal increase in the pressure on the filtrate chamber side is measured.

If the chamber in which the liquid is sealed is placed in a liquid-sealed state without providing a gas chamber, for example, a polyacrylonitrile-based polymer filtration membrane or the like easily expands due to the pressurization, so that even if there is no leakage, the pressure can be maintained. At the same time, the pressure in the liquid-sealed chamber rises to the same pressure as that on the pressurizing side, and the presence or absence of leakage cannot be detected. When the pressure is measured by sealing the gas in the chamber on the side where the gas leaks, the object of the present invention can be achieved without providing a gas chamber.

In carrying out the present invention, the types of gas and liquid used, the method of measuring pressure, and the type and form of the membrane are not particularly limited.

[0011]

The present invention will be described below based on the concretely illustrated embodiments.

[0012]

[Embodiment 1] FIG. 1 is a schematic system diagram of an example in which the present invention is applied to a leak inspection of a membrane separation device composed of a bundle of hollow fiber filtration membranes. In FIG. 1, the membrane separation device (1) is constituted by a hollow fiber filtration membrane (4) which is separated into a stock solution chamber (2) and a filtrate chamber (3). The stock solution flows from the piping system (6) through the stock solution chamber to the inside of the hollow fiber filtration membrane, and the stock solution filtered and concentrated in the meantime is discharged from the chamber (2) through the piping system (7). On the other hand, the filtered and clarified filtrate is taken out from the piping system (8) through the filtrate chamber (3). In order to apply the present invention to this system, in this embodiment, a piping system (9) for supplying a pressurized gas is connected to the stock solution piping system (6), and one of the filtrate chambers (3) is provided with a gas. A pressure gauge (PA) is provided by connecting the gas chambers (5) that are filled with air and are kept airtight, and an alarm can be issued when the pressure becomes higher than a predetermined pressure.

The procedure of the leakage inspection in this system is as follows. First, the stock solution is stopped by the valve (10), the valve (14) is opened, and the stock solution in the hollow fiber (4) and in the stock solution chambers (2) above and below are discharged out of the system. Next, the valve (1
1) is closed and the filtrate chamber is filled with liquid, and the valve (1
3) and (14) are cut off. After that, air is supplied as pressurized gas from the piping system (9) to the stock solution chamber (2) at a predetermined pressure so that the stock solution chamber (2) and the hollow fiber (4) are filled with the pressurized air. On the other hand, in the filtrate chamber (3), the filtered liquid is in a liquid-sealed state, and its pressure is the same as that of the pressurized air. At this time, the gas chamber (5) has a valve (1
Shut off in step 2) and fill with atmospheric air.

Next, by opening the valve (12), the filtrate chamber (3) is released from the liquid sealed state, and the pressure is lowered to a pressure lower than that of the pressurized air. At this time, if the filtration membrane is in a wet state, the permeation of gas in the porous membrane is significantly hindered by the surface tension of the liquid, and in the case of a sound membrane without defects, the pressure increase on the liquid side is slight, The rate of rise can be calibrated in advance. On the other hand, the gas easily leaks to the liquid side from the leak portion due to defects such as pinholes and poor sealing between the hollow fiber membrane and the main body, and the pressure inside the filtrate chamber (3) on the liquid side rises abnormally.

By thus measuring the pressure on the leaking side with a micromanometer such as a manometer, the pressure rise can be sensitively detected, and the pressure on the leaking side is much lower than that on the pressurizing side. It is less affected by the presence or absence of leaks in the piping system constituting the above, and is effective for detecting leaks due only to defects in the membrane separation device.

[0016]

Example 2 Leakage inspection of a membrane separation device using a hollow fiber membrane of polyacrylonitrile-based synthetic polymer was carried out by the method for measuring pressure as in the above example. Outer diameter φ1.3mm, inner diameter φ0.7mm, length 1100m
m, a hollow fiber membrane separation device assembled by assembling 2350 polyacrylonitrile-based synthetic polymer hollow fibers having a cut-off molecular weight of 13000, and only one hollow single yarn has one pinhole corresponding to a diameter of about 60 μm. We compared the known device with a healthy device. The filtrate chamber (3) was filled with water at room temperature, 5 kg ^G / cm ² of air was supplied to the stock solution chamber (2) as a pressurized gas, and the pressure of the filtrate chamber was measured using a manometer (Okano Seisakusho). It was measured.

FIG. 2 shows the results of time-lapse and pressure measurement when a 50 cc gas chamber was used, and FIG. 3 shows the results when a 500 cc gas chamber was used. The hatched range in the figure is the pressure rise range of a healthy membrane separation device, and the curve of the actual battle shows the pressure rise in the device having one 60 μm pinhole defect. 50cc with a small gas chamber capacity increases the pressure faster for the same amount of leakage,
Moreover, since the difference with the sound pressure of the sound device is large, the presence / absence of leakage can be determined with high sensitivity.

However, the volume of the gas chamber is not particularly limited, and should be reasonably determined based on the size of the leak defect to be detected, the pressure of the pressurized gas, the accuracy of the measuring system used, and the like. You can

[0019]

According to the leakage inspection method of the present invention, the presence or absence of leakage in the membrane separation device can be quickly inspected with high sensitivity and with little influence of leakage in the piping system.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of an example in which a leak inspection method for a membrane separation device of the present invention is applied.

FIG. 2 is a measurement result of time and pressure in the liquid side chamber in the leakage inspection method of the present invention, where the gas chamber capacity is 50 cc.
Is the case.

FIG. 3 is a measurement result of time and pressure in the liquid side chamber in the leakage inspection method of the present invention, where the gas chamber capacity is 500 c.
This is the case of c.

[Explanation of symbols]

 1 Membrane Separation Device 2 Stock Solution Chamber 3 Filtrate Room 4 Bundle of Hollow Fiber Filtration Membrane 5 Gas Chamber 6 Stock Solution Supply Pipe 7 Concentrated Stock Solution Discharge Pipe 8 Filtrate Extraction Pipe 9 Pressurized Gas Supply Pipe 10 Valve 11 Valve 12 Valve 13 Valve 14 Valve PA Pressure gauge and alarm device

Claims (2)

[Claims] 1. In a membrane separation device, one chamber isolated by a membrane is filled with a pressurized gas, and the other chamber is provided with a means for enclosing a liquid or gas and detecting the pressure. A leak inspection method for a membrane separation device, which comprises measuring the pressure of a leaking chamber. 2. The method according to claim 1, wherein the means for measuring the pressure in the liquid-filled chamber comprises providing a gas-filled gas-tight gas chamber in the liquid-filled chamber.