JPH05329398A - Dust collector electrode - Google Patents

Abstract

PURPOSE:To improve safety and dust collection efficiency by forming all the parts where the electrolysis with flat sheet-like electrodes is centralized in a curved shape when a dust collector electrode is provided. CONSTITUTION:The degree of centralization of an electrolysis can be decreased significantly by curving all the parts where an electrolytic action concentrates such as the angular part of a polygonal flat sheet-like electrode 1 positioned opposite to each other for the formation of an electrolysis. Consequently, a uniform and strong electrolytic action is realized safely, and thereby, the efficient increase of dust collection effect due to the electrolytic action is achieved. Further, if an electret is used as a filter material, it is possible to prevent the material from becoming significantly deteriorated qualitatively due to a corona discharge. Further, insulation of the electrode is dispensed with and simplifying a production process is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of electrodes in an electrostatic dust collector.

[0002]

2. Description of the Related Art Conventionally, as a dust collector for removing fine dust in the air, a dust collector that mechanically collects dust by a corrugated filter medium is used. The method of placing the filter medium in an electric field formed by at least one pair of electrodes to electrostatically collect the dust by charging the filter medium and the dust, and also as a filter medium in the above method. Known is a method that uses an electret material whose filter material itself is permanently charged to further improve the electrostatic collection ability and prevent neutralization of the permanent charge of the electret material by the electric field, thus achieving a long service life of the filter material. Has been. In such a dust collector, it is necessary for the electrodes used to not obstruct the passing air flow, and as a shape that meets this requirement, a structure in which opposing flat plate electrodes are arranged in parallel to the air flow has been put to practical use. ing.

FIG. 3 shows an example of a conventional dust collector having the functions described above. In the figure, 3 is a corrugated cloth-shaped electret filter medium, and 1 and 2 are metal plate electrodes for forming an electric field applied to the electret filter medium 3. Combined and placed parallel to the dust-laden air stream. Figure 4
Only the portions of the flat plate-shaped electrodes 1 and 2 are taken out and shown, and an electric field is formed between the flat plate-shaped electrodes 1 and 2 by applying a high voltage by a power source 5.

In the dust collector of the above construction, if the electric field formed by the flat electrodes 1, 2 is strengthened, the dust collection efficiency is improved. FIG. 5 conceptually shows this action. Further, in order to fully utilize the effect of the electric field, it is important that as many portions of the corrugated filter medium 3 as possible are in the electric field. Therefore, the flat electrodes 1 and 2 are as shown in FIG. A polygonal shape having corners such as a rectangle is preferable.

[0005]

When an electric field is formed by the flat plate electrodes in the conventional dust collector as described above, the flat plate electrodes have a portion having a significantly larger curvature than other portions such as corners. Therefore, the electric field is concentrated at that portion. Therefore, there are the following problems. (A) Since the discharge is likely to occur from the part where the electric field is concentrated, the discharge start voltage, which is the upper limit of the voltage that can be applied to the electrodes for safety, is lowered,
It becomes difficult to form a strong and uniform electric field that covers the entire filter medium. For this reason, it becomes difficult to design by fully utilizing the improvement of the dust collection efficiency by the electric field. Also, if corona discharge occurs in the area where the electric field is concentrated, if electret is used as the filter medium, the permanent charge of the electret will be neutralized by the ions generated by the corona discharge, which will cause rapid deterioration of the filter medium. Will happen. (B) In order to solve the above problem, it has been performed to apply an insulating treatment by coating or the like to the entire surface of the flat plate-like electrode to improve the applied voltage, but in this case, it is not possible to use an inexpensive insulating method such as coating. The coating film thickness is thin in the sharp portion such as the above-mentioned corner portion, and the insulation is likely to be incomplete. Further, if an attempt is made to secure a sufficient film thickness in a sharp portion, the thickness of the entire coating becomes large, which causes an increase in resistance to a passing air flow, and deteriorates the dust collecting characteristics.

Therefore, an object of the present invention is to provide a dust collector electrode which is safe and can improve the dust collection efficiency.

[0007]

In order to solve the above problems, the present invention firstly applies an electric field to a filter medium composed of a dielectric or an electret which is formed in a corrugated shape with opposed polygonal flat plate electrodes. The gist of the dust collector electrode in the dust collector having the structure is that all the portions of the flat plate electrode where the electric field is concentrated are formed in a curved shape.

Secondly, the dust collector electrode in a dust collector having a structure in which an electric field is applied to a filter material composed of a dielectric or an electret formed in a corrugated shape with opposed flat plate electrodes, wherein at least one of the flat plate electrodes is The gist of the invention is that the surface is made of metal, and an insulating layer formed by oxidation of the metal is formed at the edge portion of the flat plate electrode where the electric field is concentrated.

[0009]

In the first place, the degree of concentration of the electric field can be remarkably reduced by forming all the portions where the electric field is concentrated, such as the corners of the opposing polygonal flat plate electrodes where the electric field is to be formed, into a curved shape. As a result, it is possible to safely form a uniform and strong electric field, and it is possible to efficiently improve the dust collection efficiency due to the effect of the electric field. When an electret is used as the filter medium, it is possible to prevent the filter medium from being significantly deteriorated due to corona discharge.

Secondly, most of the surface of the flat electrode except the edge portion where the electric field is concentrated remains in the metal state, and the contact charging effect of dust particles in the atmosphere is maintained here. Further, the edge portion where the electric field is concentrated has the insulating layer formed by the oxidation of the metal from the surface toward the inside, so that the abnormal discharge due to the electric field concentration on the edge portion is stably suppressed. As a result, the dust collection efficiency is improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. This figure shows a front view of one of the flat plate-shaped electrodes in FIG. The electric field concentrates at the corners shown by the dotted line in FIG. 1, but in this embodiment, this portion is formed in a curved shape 1a, for example, an arc shape, as shown by the solid line. By adopting such a curved shape 1a, it is possible to eliminate a portion where the electric field is concentrated, and it is possible to obtain a strong electric field without easily causing discharge. Further, it does not cause deterioration of the electret filter medium due to corona discharge. Furthermore, since it is possible to eliminate the need for insulating the electrodes, it is possible to simplify the production process. Then, since the discharge is less likely to occur, it is possible to design in which the effect of the electric field is maximized. Further, as shown by reference numeral 4 in FIG. 3, the distance to the electrode on the opposite side is short, and the design can be made to be close to the portion where discharge is likely to occur.
Therefore, it is possible to apply a uniform electric field to a wider portion of the filter medium.

With the above actions and effects, it is possible to easily realize the improvement of the concentration efficiency by the electric field formation. This will be further described by a specific example. In the dust collector having the configuration shown in FIG. 3, the distance between the flat plate-shaped electrodes 1 and 4 is 4 mm, the distance at the portion 4 is 4 mm, and the corners of the flat plate-shaped electrode are processed into an arc shape of R5 as shown in FIG. The upper limit of the voltage applied between the electrodes, that is, the discharge starting voltage was 5 kV. On the other hand, it is 2.5k in the conventional example where the corners are not processed.
It was V. Further, the same pleated electret filter medium was combined with the electrodes of this example and the conventional example as shown in FIG. 3, and the dust collection efficiency was measured. In this example, the electrode applied voltage was 4.5 kV and the particle size was 0.3 μm. 32% of inflow dust was collected with respect to the above air dust. On the other hand, in the conventional example, the trapping efficiency was 25% at the applied voltage of 2 kV. Also,
Even in the case where the insulation treatment is required for safety, in the present embodiment, the corner portion is formed into the curved shape 1a, so that an inexpensive method such as coating can be adopted for the insulation treatment. As a result, manufacturability is improved. Further, since the shape is such that the sharp portion is removed, there is no danger of scratching the hand during handling, leading to improved safety.

Next, FIG. 2 shows another embodiment of the present invention. In this embodiment, for example, the oxide insulating layer 8 has a thickness of 50 μm from the tip end portion by anodic oxidation at the edge portion where the electric field is concentrated in both the comb-like plus plate electrode 7 and the minus plate electrode 6 made of Al material. Beam portions 61 of the comb-shaped electrodes 6 and 7,
It is formed over at least 100 μm toward 71. As the metal forming the electrode surface layer, in addition to Al described above, Ti, V, Y, Zr, Nb, W,
At least one of In, La, Hf, and Ta can be used. This is because these metals are easily subjected to insulation treatment by oxidation, particularly insulation treatment by anodic oxidation.

Next, the operation and effect will be described. As Comparative Example 1, one in which the electrode was left in a metallic state made of an Al material,
As Comparative Example 2, the entire surface of the electrode of Comparative Example 1 was subjected to oxidation insulation treatment, and each was subjected to evaluation. Table 1 shows the spark generation voltage of the dust collectors equipped with the electrodes of the dust collecting portion of this example and the comparative example.

[0016]

[Table 1] In the present Example and Comparative Example 2, no spark discharge occurred at an applied voltage of 8 kV or less, but in Comparative Example 1, a spark was generated at 2.4 kV. Therefore, as can be seen from Table 1, when the electrodes according to the present embodiment are used, the inter-electrode distance can be shortened under the same applied voltage as compared with the conventional metal-state electrodes and those coated with the insulating coating, and the inter-electrode distance In this case, the applied voltage can be increased.

Table 2 shows the initial dust collection efficiency and the dust collection efficiency reduction rate after 100 hours of the dust collection operation.

[0018]

[Table 2] In this example, it is recognized that the initial dust collection efficiency is higher than that of Comparative Examples 1 and 2, and at the same time, the degree of decrease in dust collection efficiency after 100 hours has been smallest.

In the flat plate electrode, a combination of the above-mentioned one embodiment and other embodiments, that is, all the portions where the electric field is concentrated are formed in a curved shape, and an insulating layer by oxidation of metal is formed at the edge portion. You may. If both are combined, the safety can be further improved and the dust collection efficiency can be improved.

[0020]

As described above, according to the present invention,
First, since all the portions of the flat plate electrode where the electric field is concentrated are formed in a curved shape, it is possible to significantly reduce the concentration of the electric field and safely form a uniform and strong electric field. It is possible to efficiently improve the dust collection efficiency. In addition, it is possible to improve the manufacturability by simplifying the electrode processing steps such as insulation treatment, and further improve the safety during handling.

Secondly, since at least one of the flat plate-shaped electrodes has a surface made of metal and an insulating layer formed by oxidation of the metal is formed at the edge portion of the flat plate-shaped electrode where the electric field is concentrated, spark discharge is caused. It is possible to stably suppress the typical abnormal discharge. In addition, since the portion of the flat electrode other than the edge portion where the electric field is concentrated is in a metal state, the contact charging effect of the atmospheric dust particles on the electrode surface is maintained, and the dust collection efficiency is improved as compared with the case where the entire surface insulation treatment is performed. Furthermore, since the insulating layer at the edge portion is formed by the oxidation treatment, peeling does not occur due to maintenance such as electrode cleaning, and the life can be improved.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a dust collector electrode according to the present invention.

FIG. 2 is a perspective view showing another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional dust collector.

FIG. 4 is a perspective view of a flat electrode part in the conventional dust collector.

FIG. 5 is a diagram showing the relationship between the electric field strength and the amount of improvement in dust collection efficiency due to the electric field in a dust collector having a configuration in which an electric field is applied to a filter medium.

[Explanation of symbols]

 1, 6, 7 Flat plate electrode 1a Curved part 8 Insulation layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Hattori 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa, Ltd. Inside the Toshiba Living Space Systems Engineering Laboratory (72) Incorporator Takaki Iwanaga 8 Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Banchi Co., Ltd. Inside the Toshiba Living Space Systems Technology Laboratory

Claims (2)

[Claims] 1. A dust collector electrode in a dust collector having a structure for applying an electric field to a filter medium composed of a dielectric or an electret formed in a corrugated shape with facing polygonal flat plate electrodes, wherein the electric field of the flat plate electrodes is The dust collector electrode is characterized in that all the concentrated portions are formed in a curved shape. 2. A dust collector electrode in a dust collector having a structure in which an electric field is applied to a filter material made of a dielectric or an electret formed in a corrugated shape with opposed flat plate electrodes, and at least one of the flat plate electrodes has a surface thereof. A metal dust collector electrode, and an insulating layer formed by oxidation of the metal is formed at an edge portion of the flat plate electrode where the electric field is concentrated.