JP2704903B2 - Water removal method for insulating liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention is intended to purify an insulating liquid, such as a hydraulic fluid of a grinding machine, in which water is constantly mixed, and particularly to purify water. It relates to the removal method.

More specifically, the effect of moisture in an insulating liquid can be reduced by using an electrostatic filter nonwoven fabric (hereinafter, also referred to as an electret nonwoven fabric) in which permanent static electricity is polarized or oriented, or by combining the electret nonwoven fabric with a highly water-absorbing nonwoven fabric. The present invention relates to a method for removing water from an insulating liquid, which is coagulated, enlarged and removed.

(Prior Art) Conventionally, various methods have been proposed as a method of removing water from an insulating liquid found in a hydraulic fluid of a grinding machine or a cutting machine or the like in which water is mixed intensely.

For example, stationary separation, centrifugal separation, methods using highly water-absorbing resin particles and fibers are available, but stationary separation requires a large area and a long time, and centrifugal separation is used for cleaning inside the separator. Efforts are required, and the superabsorbent resin has the disadvantage that the separation element is rapidly consumed when a large amount of moisture or dust is mixed.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned drawbacks in the conventional method for removing water from an insulating liquid.

An object of the present invention is to provide a simple and reliable method for removing a large amount of water mixed in a short time without taking up space, reducing the consumption of a water removal element.

[Configuration of the invention]

(Means for Solving the Problems) To summarize the present invention, the present invention relates to a method for removing moisture from an insulating liquid having a high moisture content, the method comprising: The present invention relates to a method for removing water from an insulating liquid, comprising passing an oriented fiber through an electrostatic filter nonwoven fabric layer, or passing through the electrostatic filter nonwoven fabric layer, and then passing through a hydrophilic nonwoven fabric layer. is there.

 Hereinafter, the configuration of the present invention will be described in detail.

The present inventors have previously proposed an electrostatic filter element for an insulating liquid having a structure in which an electret nonwoven fabric is wound and laminated on a plastic pipe material or the like (Japanese Patent Application No. 1-48).
No. 56).

The electrostatic filter element is used for purifying the contaminated insulating liquid in order to efficiently adsorb and capture dust (fine particles) existing in the insulating liquid such as mineral oil and organic solvent. is there. The principle of removing fine particles (dust) from the element is as follows. When an insulating liquid is passed through the element, the surface charges of the fine particles (dust) and the orientation-polarized charges of the element act on each other,
It is adsorbed and captured by the element.

However, when the electret nonwoven fabric passes an insulating liquid containing a large amount of moisture or moisture and dust in a subsequent study, the electret nonwoven fabric performs a function of applying an electric field (charger). A new finding has been found that the fine water that is present is agglomerated and coarsened.

At this time, fine particles (dust) in the insulating liquid are adsorbed to the layer of the electret nonwoven fabric, but fine sludge such as a modified substance of oil, an additive in a water-soluble cutting fluid, or a modified substance thereof is used. Some of the material, or debris, is incorporated into the coagulation droplets. It was also found that when the oil discharged from the layer of the electret nonwoven fabric was allowed to stand, the above-mentioned various contaminants also settled together with the settling of water.

That is, this is because the electrostatic filter element using the electret nonwoven fabric itself has a much larger amount of dust trapping compared to the existing filter element, and the filter together with the coarse water droplets of the trapped dust. Discharge from the element means that the electrostatic filter element is not only very effective as an element for removing water from an insulating liquid having a high water content, but also extends the life of the element tremendously.

As described above, the effectiveness was confirmed when the electret nonwoven fabric was used as a water removal filter for an insulating liquid having a high water content, but it was unsatisfactory to obtain a desired water removal rate. In the present invention, what is known may be used as the electret nonwoven fabric.

In the present invention, in order to secure a desired high water removal rate, a water removal filter made of a hydrophilic nonwoven fabric can be used in addition to the single use of the electrostatic filter element made of the electret nonwoven fabric.

In the present invention, when a hydrophilic nonwoven fabric layer is used as a secondary element for water removal, water droplets coarsened to some extent by the electrostatic filter element as the primary element are further promoted by the secondary element. ,
Moisture and contaminants settle out of the secondary element in a single hour,
The water removal rate can be greatly improved.

The hydrophilic nonwoven fabric constituting the secondary element is not particularly limited as long as it is manufactured from hydrophilic fibers. For example, a water swellable fiber having a water swelling degree of 2 to 20 cc / g shown in JP-B 64-8561 alone or an aggregate with other fibers, and a fiber aggregate having a density of 0.002 to 0.05 g / cm ³ A dewatering filter composed of:

A filter material composed of water-absorbing fibers having the above-mentioned water swelling degree characteristics and having a specific density effectively forms water droplets by coarsely dispersing water dispersed in an insulating liquid. It can be separated and removed.

Next, a method for removing water from an insulating liquid having a high moisture content using an electrostatic filter element as a primary element of the present invention and a hydrophilic nonwoven fabric filter element as a secondary element based on the drawings. explain. It goes without saying that the present invention is not limited to the illustrated ones.

FIG. 1 is a schematic view of a water removal device of a first embodiment used in the water removal method of the present invention. FIG. 2 is a sectional view of a water removal method of a second embodiment used in the water removal method of the present invention.

As shown in FIG. 1, a water aggregating element (11) made of an electret nonwoven fabric constituting a water removing device (A)
And a water removal element (21) made of a hydrophilic non-woven fabric are independently disposed in a dedicated water agglomeration tank and a water removal tank, respectively. These elements are provided with an insulating liquid such as a hydraulic pressure for a grinding machine having a high water content. Pass the hydraulic oil to remove water. The moisture aggregating element (11) is manufactured by winding and laminating an electret nonwoven fabric on a porous support, for example, a porous plastic pipe (not shown). As described above, the electret nonwoven fabric strongly adsorbs dust, grinding dust, and the like in the processing oil, so that passage of the processing oil is inhibited with time. In order to solve this, an inflow portion such as a hole having a depth that does not reach the porous support may be provided in the electret nonwoven fabric layer.

The water removal device (A) shown in FIG. 2 is a device in which the independent type water condensation element (11) and the water removal element (21) shown in FIG. 1 are integrated on a porous support (3). Thus, the device itself is made compact. For example, a hydraulic fluid for a grinding machine containing water is introduced from the inflow direction shown in the drawing,
The water passes through the porous support (3) to reach the water aggregating element, where the water is coarsened, and then becomes water droplets in the water removing element (21), from which water is separated.

In the present invention, in order to highly remove water, in addition to the water removal device shown in FIGS. 1 and 2, a water removal element made of a superabsorbent resin or fiber may be added. Needless to say.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these embodiments.

(Example 1) basis weight 20 g / m ^2, a length of 25m electret nonwoven fabric on the outer periphery of the porous plastic tube wound into a roll type was fabricated diameter elements 60 mm, length 500 mm. The element was provided with conical holes extending at 3 cm intervals to reach 2/3 of the layers in the stack. Then, the element was placed in a housing designed so that an insulating liquid containing a large amount of water, which was finely dispersed, entered from the outside and exited from the center, to form a moisture aggregation element (coalescer).

On the other hand, 70% of acrylic composite fiber and polyolefin composite fiber (low density polyethylene: crystalline polypropylene =
1: 1) A non-woven fabric was prepared from 30%, and an aqueous solution of caustic soda was evenly sprayed on the non-woven fabric and heat-treated in an autoclave. The non-woven fabric having an outer layer hydrogelated in this manner was wrapped around the outer periphery of a porous plastic cylinder having a diameter of 30 mm and a length of 247 mm to obtain a water removal element. The water removing element is disposed in a housing different from the housing of the water aggregating element, and discharges an insulating liquid containing water coarsened by the water aggregating element from a central portion of the element to the outside. Used in an embodiment (see FIG. 1).

The water removal device was constantly connected to the hydraulic oil tank 200 of the grinding machine where water was mixed, and water removal was performed for 1.5 months at an oil flow rate of 1.4 / min. As a result, an average of 100 ml of water was settled and discharged every day at the lower part of the water removal element. The water content and cleanliness in the oil tank are as shown in Table 1.

(Example 2) Using the same water aggregating element and water removing element as in Example 1, it was connected to the hydraulic oil tank 100 of the grinder and processed under the same conditions for one month. The results are shown in Table 2.

[Effects of the Invention] In the present invention, as a method for removing water from an insulating liquid having a high water content, an element for mainly aggregating water finely dispersed in the insulating liquid, and then water is further coarsened. This includes an embodiment using two types of functionally differentiated elements, that is, elements that are formed into water droplets, and water can be removed effectively. That is, since the electrostatic electret nonwoven fabric is used for agglomeration of finely dispersed water and the superabsorbent nonwoven fabric is used for forming water droplets, the water removal efficiency is extremely high.

Further, in the present invention, in addition to water present in the insulating liquid, for example, dust (solid fine particles), fine sludge of a modified substance of oil or a modified substance of an additive component in a water-soluble cutting fluid, and the like are simultaneously formed with water droplets. Since it is taken in, it is also effective in removing these impurities. This is an important point in greatly extending the life of each of the above-mentioned elements employed in the water removal method of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic view of a water removal device of a first embodiment used in the water removal method of the present invention. FIG. 2 is a sectional view of a water removal device of a second embodiment used in the water removal method of the present invention. A: Water removal device 1 ... Water condensation tank 2 ... Water removal tank 3 ... Porous support 11 ... Water condensation element 21 ... Water removal element

Claims (9)

(57) [Claims] 1. A method for removing water from an insulating liquid having a high water content, wherein permanent water is passed through an electrostatic filter non-woven fabric layer of fibers with polarization and orientation, and fine water droplets are aggregated to remove water. A method for removing water from an insulating liquid. 2. The method for removing water from an insulating liquid according to claim 1, wherein the non-woven fabric layer of the electrostatic filter is formed on a porous support. 3. A method for removing water from an insulating liquid having a high water content, comprising:
A method for removing water from an insulating liquid, comprising passing water through an electrostatic filter nonwoven fabric layer of fibers in which permanent static electricity is polarized and then passing through a hydrophilic nonwoven fabric layer. 4. The method of removing an insulating liquid according to claim 3, wherein the electrostatic filter nonwoven fabric layer and the hydrophilic nonwoven fabric layer are formed on separate porous supports. 5. The method for removing an insulating liquid according to claim 4, wherein the electrostatic filter nonwoven fabric layer and the hydrophilic nonwoven fabric layer are each wound and laminated on a porous support. 6. The water removal of an insulating liquid according to claim 5, wherein the electrostatic filter non-woven fabric layer is provided with an inflow portion of the insulating liquid at a depth not reaching the surface of the support in the laminated portion. Method. 7. The method according to claim 1, wherein the insulating liquid having a high water content passes through the non-woven fabric layer of the electrostatic filter and into the porous support, and then from the porous support into the non-woven fabric layer. Item 5. The method for removing water from an insulating liquid according to Item 4. 8. An electrostatic filter nonwoven fabric layer and a hydrophilic nonwoven fabric layer are formed by winding and laminating an electrostatic filter nonwoven fabric on the same porous cylinder, and then winding and laminating a hydrophilic nonwoven fabric. Item 14. The method for removing water from an insulating liquid according to Item 7. 9. The insulating liquid according to claim 8, wherein the insulating liquid having a high water content is allowed to pass through the porous non-woven fabric layer and then through the hydrophilic non-woven fabric layer from inside the porous cylinder. For removing ionic liquids.