JPH07232099A - Electric precipitator - Google Patents

Abstract

PURPOSE:To improve a dust collection efficiency to obtain a miniaturized device in an electric precipitator which adsorbs dust due to an electric discharge which takes place between poles. CONSTITUTION:Openings (p) are provided in rectangular dust collection polar plates 2 which constitute a dust collection polar plate group. The opening is circular or elliptic, and covers 10 to 50% of the total area. When an electric precipitator is activated, an intensified electric current runs on the surface of the dust collection polar plate 2 and becomes susceptible of dust settlement. However, as the air flow generates toward the opening, dust seldom accumulates and grows not as is the case with a conventional dust collector. In addition, the whole device can be scaled down because a charging distance can be short.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic precipitator for use in power plants, cement factories, industrial incinerators, roads, tunnels, for removing fine particles, for removing radioactive dust, or for cleaning indoor air. Is.

[0002]

2. Description of the Related Art An electrostatic precipitator is based on the principle that dust, dust, etc. (hereinafter referred to as "dust") adhere to the discharge part of a machine using a high voltage, and the case does not A discharge electrode (negative electrode) for generating a uniform electric field and a dust collection electrode for adhering dust are provided to face each other with a gap, and a high voltage is applied to both electrodes to separate the discharge electrode and the dust collection electrode. It is designed to be discharged into the air between. Negative discharge is also used as opposed to positive discharge, which generates less ozone.

The inventor of the present application has already proposed a conventional electrostatic precipitator. For example, as shown in FIG. 8, a plurality of holes 5a are formed on the surface of the dust collecting electrode plate 5 so as to be orthogonal to the air flow direction (arrow direction) for the purpose of collecting dust. Between the dust collecting electrode plates 5, a plurality of discharge electrode plates 6 each having a mountain-shaped pierced portion 6a continuously formed on the edge side of a metal rectangular plate are provided in parallel with the surface parallel to the flow direction. A dust device 1 has been proposed.

As another conventional example, FIGS. 9 and 10 show an electrostatic precipitator filed by the inventor of the present application on January 31, 1994. The rectangular dust collecting electrode plate 2 is a spacer 7 (7a, 7b, 7c)
The space between the spacers 9 (9a, 9a, 9a, 9a, 9b) (space adjustment means) are sandwiched and connected to form a discharge electrode plate group 10.

In the electrostatic precipitator 1 shown in FIG. 10, units 11 in which a discharge electrode plate group 10 is arranged and fixed between each of a plurality of dust collecting electrode plate groups 8 are arranged in parallel in several casings. The dust collecting electrode plate group 8 and the discharge electrode plate group 10 are fixed to the frame body of the unit 11 by screws 13 protruding from the ends of the spacers 7 and 9. Then, the high-voltage negative electrode is connected to the discharge electrode plate group 10, the positive electrode is connected to the dust collecting electrode plate group 8, and the air to be treated by the blower is passed between the electrodes.

In this apparatus, as shown in FIG. 11, when a discharge electrode plate group 10 is arranged between two dust collecting electrode plate groups 8 and a high voltage is applied, a discharge current flows, causing a three-dimensional and complicated inequality. Generates an electric field. In the discharge electrode plates 6 of the discharge electrode plate group 10, since the adjacent planes have the same potential, there is no electric field, and the adhesion of the oppositely charged particles m- is significantly reduced. The charged dust m is
It is adsorbed and deposited on the downstream end of the dust collecting electrode plate group 8 facing the upstream end of the discharge electrode plate group 10. If it is accumulated too much, the surface of the dust m becomes slippery and escapes from the constraint of the electric field to be scattered. Will be done. When the dust particles are hardened and accumulated and cannot be supported by the suction force, the dust particles m fall down. In this way, the dust in the air to be treated is adsorbed and falls, so that the air is purified.

Further, the plane of the dust collecting electrode plate 2 is vertical, and due to the unequal electric field, the attached dust m is attached and deposited on the adjacent dust collecting electrode plate 2, grows and drops. Discharge electrode plate group
In the case of 10, the amount of reversely charged particles m-attached is small, so that the discharge resistance is small, a strong discharge current can be maintained, and the life of the machine can be lengthened.

[0008]

However, when these devices are continuously used, the collected dust may show a state of adhesion to the electrodes as shown in a partially enlarged view in FIG. It was found by the observation of the present inventor. That is,
After starting to use the dust collecting electrode plate 2, first, dust begins to adhere to the tip of the processing air in the flow direction, where the dust grows and becomes almost a bullet shape. Is thicker, and is thinner toward the rear, and the portion b is attached to the rear in a mountain shape, and then the portion c is attached on b in the same manner. The situation of adhesion is not limited to two layers, but may be three layers in some cases. Then, the accumulated dust cannot bear the weight or falls due to the impact due to the spark discharge between the discharge electrode plate 6 and the dust collecting electrode plate 2. When the dust grows, the dust collecting electrode plate 2 is covered with the dust, so that the dust collecting effect decreases during that period, and when the device is used for a long time, the dust collecting efficiency becomes a problem. Become.

According to the observation by the inventor of the present application, the cause of dust gathering as shown in FIG. A detailed view of how dust is accumulated on the dust collecting electrode plate 2 (during dust collection process). As shown in FIG. 3, in the initial stage of dust collection, a large amount of dust gathers in the central portion and gradually gathers around it. You can see dust circles with decreasing density.
The actual diameter of this circle is considered to be about twice the distance c between the discharge electrode plate 6 and the dust collecting electrode plate 2 in FIG. When this is viewed on the dust collecting electrode plate 2, when the current from the discharge electrode plate 6 reaches the dust collecting electrode plate 2 as shown in FIG. Can be assumed to be the maximum and the current intensity circle gradually decreases around that. In FIG. 4, the letter A is large at the center and small on the circumference, which is taken into consideration. The circumference is drawn as a model on the drawing, but it is considered that the circumferences actually overlap each other due to the current density.

In order to improve the dust collection efficiency, the number of electrode plates has been increased and the arrangement thereof has been devised, but they have limitations. Further, due to recent recognition of environmental problems, removal of dust and the like from existing factory equipment, such as cement manufacturing plants and industrial incinerators, has become a problem. However, the above-mentioned factory has an enormous amount of air for processing purposes, and the conventional electrostatic precipitator does not meet the expectation in view of its scale and efficiency. Therefore, an object of the present invention is to provide an electrostatic precipitator having a small size and improved dust collecting efficiency.

[0011]

In order to achieve the above-mentioned object, the present invention provides a plurality of rectangular dust collecting electrode plates provided with openings with the planes of the dust collecting electrode plates being vertical. , The planes are opposed to each other and arranged in parallel, and the first electrode is provided between the dust collecting electrode plates.
Is fixed in a fence shape via the interval adjusting means, and the fence-shaped dust collecting electrode plate group is placed in parallel with the plane in parallel to the flow direction of the gas flow path, with a plurality of intervals provided therebetween. A plurality of rectangular plates are formed with barbed portions on both edge sides, and the planes of the discharge electrode plates are made vertical, and the planes are opposed to each other and arranged in parallel, and a second gap is adjusted between the discharge electrode plates. It is fixed in the form of a fence via a means, and the fence-shaped discharge electrode plate group is made parallel to the plane with respect to the flow direction of the gas flow path, with an interval provided between each of the dust collecting electrode plate groups. It is characterized in that it is provided. Also,
In the above configuration, the shape of the opening provided in the dust collecting electrode plate is characterized by being a circle or an elongated hole, further the area of the opening provided in the dust collecting electrode plate,
It is characterized by occupying 10 to 50% of the area of the dust collecting electrode plate.

[0012]

Since the present invention is configured as described above, the current from the discharge electrode plate is concentrated in the portion between the openings,
Even if the attached dust tries to grow further, the area of the dust collecting electrode plate to which it adheres is small, and since the excessive dust growth is suppressed by the air flow through the opening, the dust that adheres to the collecting electrode plate falls. However, the growth of dust unlike the conventional case is not seen (equalization of air flow), and the dust collection efficiency of the device is not deteriorated even after long-term use. The fall of the attached dust from the dust collecting electrode plate is caused not only by the flow of air but also by the impact of the spark discharge from the discharge electrode plate to the dust collecting electrode plate.
Also, since dust adheres to the dust collecting electrode plate and grows, it immediately drops, increasing the amount of air sent in per unit area,
The charging distance (the distance that the air sent into the device can be charged before it leaves the device, actually the length of the device) can be short. This makes it possible to reduce the weight of the device because the entire device can be downsized.

[0013]

Embodiments of the present invention will be described below with reference to FIGS. 1, 5 and 6. Description of the same reference numerals in FIGS. 1 and 9 will be omitted. As shown in FIG. 5, the dust collecting electrode plate 2a
In this case, four circular openings p are provided as openings in the order of 3 and from the end thereof. The circular opening is provided from end to end of the dust collecting electrode plate 2a, and the ratio of the area of the entire opening to the area of the dust collecting electrode plate is 10 to 50%. The types of openings are not limited to circles, but the dust collection electrode plate 2 shown in FIG.
An elongated hole such as p'of b may be used. As shown in FIG. 1, the dust collecting electrode plate 2a thus provided with openings is installed in place of the dust collecting electrode plate 2 in FIG. 9, and when the air to be treated is sent into the device, the discharge electrode The current from plate 6 is shown in FIG.
Since the current is concentrated as shown by the arrow and the current density on the dust collecting electrode plate 2 is increased without the current being dispersed, the dust adhesion efficiency is improved as compared with the conventional case.

Therefore, although the amount of dust adhered is greater than in the conventional case, even if the dust adheres to the dust collecting electrode plate 2, air flows immediately through the opening of the dust collecting electrode plate 2 as shown in FIG. As a result, it is scraped off and peeled off, or even if it adheres, it falls by its own weight before it becomes excessive (it grows faster than the conventional one, but it falls because it cannot bear its own weight). The cause of the drop is not only the flow of air but also the impact from the spark discharge from the pierced portion 6a of the discharge electrode plate 6 to the dust collecting electrode plate 2. Therefore, even if the dust a adheres to the end portion of the dust collecting electrode plate 2 at the initial stage of dust collection, the dust does not grow thereafter, and the portion a is also deposited to some extent and then falls due to its own weight.

[0015]

Since the present invention is constructed as described above, the following effects can be obtained. That is, there is an increase in the amount of dust collected on the dust collecting electrode plate due to an increase in the current density from the discharge electrode plate to the dust collecting electrode plate, and although the dust that has adhered grows and becomes larger, due to the air flowing through the opening, Peel off the dust collecting electrode plate early and fall. In addition, the attached dust drops due to the impact caused by the spark discharge between the discharge electrode plate and the dust collecting electrode plate. Further, since the charging distance is reduced, the entire apparatus is downsized and the weight is reduced, and the volume is about 1/5 to obtain the same efficiency as the conventional one. In addition to these effects,
The first and second interval adjustments can be performed without losing the effect of the ease of assembling work of the entire device of the related art (filed on January 31, 1994) by using the interval adjusting means in a multi-stage manner. By the means, it becomes easy to narrow the gap between the same electrodes as it goes downstream, or to shorten the gap between different electrodes as it goes downstream, so that the multi-stage configuration can be fully utilized. It is possible to provide a high performance dust collector.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of an electrostatic precipitator according to an embodiment of the present invention.

FIG. 2 is a partial view showing how dust adheres to a conventional dust collecting electrode plate.

FIG. 3 is a model drawing of a state in which dust adheres to a dust collecting electrode plate, viewed microscopically.

FIG. 4 is a diagram showing a model representing a current intensity on a dust collecting electrode plate.

FIG. 5 is a view showing an embodiment in which an opening is provided in the dust collecting electrode plate according to the present invention.

FIG. 6 is a view showing another embodiment in which an opening is provided in the dust collecting electrode plate according to the present invention.

FIG. 7 is a partial cross-sectional view of an embodiment in which an opening is provided in the dust collecting electrode plate.

FIG. 8 is a perspective view of a main part of a conventional electrostatic precipitator.

FIG. 9 is a perspective view of a main part of an electrostatic precipitator currently applied for a patent by the inventor of the present application.

10 is a plan view showing the arrangement of electrode plates of the electrostatic precipitator in FIG.

FIG. 11 is a plan view for explaining the action of the electrode plate of the electrostatic precipitator in FIG. 9.

[Explanation of symbols]

 2 Dust collecting electrode plate 2a Dust collecting electrode plate provided with opening p Opening 6 Discharge electrode plate 6a Stab part 7 First spacer 8 Dust collecting electrode plate group 9 Second spacer 10 Discharge electrode plate group

Claims (3)

[Claims] 1. A plurality of rectangular dust collecting electrode plates provided with openings are arranged such that the planes of the dust collecting electrode plates are vertical and the planes are opposed to each other in parallel, and the dust collecting electrode plates are arranged in parallel with each other. First
Is fixed in a fence shape via the interval adjusting means, and the fence-shaped dust collecting electrode plate group is placed in parallel with the plane in parallel to the flow direction of the gas flow path, with a plurality of intervals provided therebetween. A plurality of rectangular plates are formed with barbed portions on both edge sides, and the planes of the discharge electrode plates are made vertical, and the planes are opposed to each other and arranged in parallel, and a second gap is adjusted between the discharge electrode plates. It is fixed in the form of a fence via a means, and the fence-shaped discharge electrode plate group is made parallel to the plane with respect to the flow direction of the gas flow path, with an interval provided between each of the dust collecting electrode plate groups. An electrostatic precipitator characterized by being provided. 2. The electrostatic precipitator according to claim 1, wherein the shape of the opening provided in the dust collecting electrode plate is a circle or an elongated hole. 3. The electrostatic precipitator according to claim 1, wherein the area of the opening provided in the dust collecting electrode plate occupies 10 to 50% of the area of the dust collecting electrode plate.