JP3270184B2 - How to save the membrane module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for storing a membrane module used for solid-liquid separation or the like.

[0002]

2. Description of the Related Art A membrane module has no phase change.
Since solid-liquid separation can be performed, it has been used in various applications because of low energy consumption and no denaturation of substances. Semi-permeable membranes such as reverse osmosis membranes and ultrafiltration membranes lose their function when dried, and porous membranes such as microfiltration membranes can be immersed in a liquid with low surface tension, such as alcohol, even after drying. If the membrane is replaced with water afterwards, the function of the membrane will be restored, but the work is troublesome, so usually store the membrane module with water filled or store in a wet state with water filled in the pores of the membrane. ing. When water is stored in the module with water, the membrane does not dry, but since it is heavy, a method of storing it in a wet state has recently been generally used.

[0003]

When a module is stored in a wet state, the module is packaged and stored in a polyethylene film having low moisture permeability in order to prevent the membrane from drying. However, in the case of a polyethylene film, if the film is exposed to high temperatures or changes in temperature during storage, the membrane dries, and in the case of a semipermeable membrane module, the function of the membrane is lost. Although the function can be restored by such means as above, if air leak check is performed to check the soundness of the module, even if the film is not broken, the air will be leaked. , There was a problem that it could not be determined.

The present invention provides a method of storing a membrane module in a wet state stably without drying and losing the function of the membrane even when exposed to a high temperature or subjected to a temperature change. .

[0005]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies and, surprisingly,
It has been found that even with a film having a higher water vapor permeability than a polyethylene film, the film is much harder to dry than packaging with a polyethylene film. That is, the main cause of drying of the membrane is that air enters the film packaging the membrane module and the humidity inside the film temporarily decreases rather than being caused by the permeation of water vapor, but by the temperature change of the outside air. The present inventors have found out that this is the cause and completed the present invention.

That is, according to the present invention, in storing the membrane module in a wet state, the membrane module is packaged with a film containing at least one of polyvinylidene chloride resin, ethylene-vinyl alcohol copolymer resin and nylon resin. This is how to save. The membrane in the present invention can be applied to any membrane such as a reverse osmosis membrane, an ultrafiltration membrane, and a microfiltration membrane, and is not limited to the shape of the module. Further, the material of the film is not limited, but it is particularly effective for a hydrophobic polymer film such as a polysulfone resin, a polyethersulfone resin, a polyvinylidene chloride resin, a polyvinyl chloride resin, and a polyolefin resin.

The wet state in the present invention refers to a state in which water in the module has been drained, and a state in which at least the film contains water having a saturated water content or more. Of course, when the module is stored in a wet state, it may contain a bactericide such as formalin. The film of the present invention can be used as a single film of polyvinylidene chloride resin, ethylene-vinyl alcohol copolymer resin, and nylon resin. It is preferable to use a multilayer film using a polyethylene film for the inner layer.

Hereinafter, the present invention will be described in detail with reference to examples.

[0009]

Example 1 A porous hollow fiber membrane made of polyethylene (outer diameter 1.25 mm, inner diameter 0.68 mm, average pore diameter 0.1 μm)
) A suspension type external pressure filtration module having an outer diameter of 5 inches and a length of 2.5 m including 4200 pieces was confirmed to be free of membrane leakage at an air pressure of ² kg / cm ² , and then water was drained and a folding width was set. After being packaged in a multilayer film of polyvinylidene chloride resin and polyethylene having a thickness of 300 mm and a thickness of 60 μm (polyvinylidene chloride resin film having a thickness of 10 μm) and stored in a constant temperature room at a temperature of 45 ° C. and a relative humidity of 40% for 120 hours, A leak check was performed, but no leak was found.

[0010]

[Comparative Example 1] The same module as in Example 1 was folded at a folding width of 300.
mm, and wrapped in a low-density polyethylene film having a thickness of 100 μm.
After storing in a 0% constant temperature room for 5 hours, the module was checked for leaks. Leaks from 10 or more hollow fiber membranes were observed. The module was immersed in alcohol, washed with water, and then subjected to a leak check after the leak test. As a result, no leak was found, and it was found that the leak was caused by drying of the film.

The water vapor permeability of the polyvinylidene chloride resin-polyethylene multilayer film used in Example 1 and the polyethylene film used in Comparative Example were determined by ASTM E96.
When measured according to -53T, there was almost no difference between them, and the polyvinylidene chloride resin multilayer film was slightly larger.

[0012]

Example 2, Comparative Example 2 A module obtained by packaging the module of Example 1 in a wet state with a multilayer film containing polyvinylidene chloride of Example 1 and a nylon resin and an ethylene-vinyl alcohol copolymer resin. Two modules each of which were packaged with a G type of 100 μm thick cans film manufactured by Shikoku Kako Co., Ltd., and two modules each packed with the polyethylene film used in Comparative Example 1 were compared at a temperature of 38 ° C. and a relative humidity of 40%. Time, temperature 20
After performing a cooling / heating cycle test twice a day for 2 hours at 2 hours each for 4 hours at 50 ° C. and a relative humidity of 50% for 2 months,
When the module was subjected to a leak test, the module wrapped with the polyvinylidene chloride resin multilayer film and the module wrapped with the canes film did not leak due to drying of each of the two modules. In each of the two modules, leakage occurred from 100 or more hollow fiber membranes, and the water permeability was reduced to 85% of the initial value.

[0013]

By wrapping the membrane module with a film containing at least one of the polyvinylidene chloride resin, ethylene-vinyl alcohol copolymer resin and nylon resin of the present invention, the wet membrane module can be kept at a high temperature for a long time or Even when exposed to a temperature change, the membrane can be stably stored without drying and without losing the function of the membrane.

Claims (1)

(57) [Claims] In storing a membrane module in a wet state, the membrane module is packaged with a film containing at least one of polyvinylidene chloride resin, ethylene-vinyl alcohol copolymer resin and nylon resin. Method.