JPH0568912A - Electric precipitator - Google Patents

Abstract

PURPOSE:To facilitate maintenance such as the washing of electrodes by constituting the electrode on a low potential side in a dust collecting part wherein appropriate potential difference is applied across opposed electrodes by applying ceramics coating having specific divalent metal ion oxide added thereto to the surface of a metal substrate. CONSTITUTION:In an electric precipitator, high voltage of about 4.2kV is applied between a pair of discharge electrodes 1, 2 in a charging part 10 on an upstream side to generate corona discharge and dust 3 in air is charged by this corona discharge to be collected on a dust collecting electrode 4. In this case, the dust collecting electrode 4 on a low potential side among both electrodes 4, 5 in a dust collecting part 20 is formed by applying a ceramics coating film 7 of V2O5-P2O5 containing about 5mol% of MgO to the surface of an SUS foil 6 with a thickness of about 100mum being a metal substrate by a sol-gel coating method using metal alkoxide as a starting raw material. Both terminals of the dust collecting electrode 4 and the opposed electrode 5 are held between the dust collecting electrodes and the dust collecting electrodes are fixed by an insulating support to constitute the dust collecting part 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic precipitator, and more particularly to improvement of its electrode part.

[0002]

2. Description of the Related Art Electric dust collectors have the following main functions:
It has two functions: a charging function that causes corona discharge between the discharge electrode and the counter electrode, and that corona discharge charges dust in the air, and a dust collecting function that collects the charged dust. .. Among them, the dust collecting portion is composed of a dust collecting electrode and a counter electrode which are arranged to face each other with an appropriate interval. As the dust collecting electrode, a stainless plate, a stainless foil, or an electrically insulating polymer film having a surface coated with a conductive paint is used. Then, a voltage equal to or lower than the voltage applied between both electrodes of the discharge part is applied between the dust collecting electrode and the counter electrode so that the charged dust is collected.

[0003]

The conventional electrostatic precipitator has the following problems.
A metal such as a stainless steel plate or a polymer film whose surface is coated with a conductive paint has been used for the dust collecting electrode. However, when a metal is used for the dust collecting electrode, spark discharge may occur between the end faces of both electrodes unless the distance between the counter electrode and the applied voltage is strictly controlled. Further, when a polymer film having a surface coated with a conductive paint is used, if the paint is applied to the entire surface, spark discharge may occur at the end surface of the film. When the conductive paint is not applied to the end surface of the polymer film but is applied to the central part of the polymer film, the width of the polymer film becomes wider and the depth of the dust collecting part becomes larger than that when applied to the entire surface. There was a problem. If the distance between the dust collecting electrode and the counter electrode is increased in order to avoid the occurrence of spark discharge between the end faces, the dust collecting efficiency decreases exponentially as the distance between the electrodes increases.

In order to avoid the spark discharge problem at the end face,
Japanese Unexamined Patent Publication (Kokai) No. 48-88554 discloses that 10 ⁵ -1 is formed on the surface.
An electrostatic precipitator in which a semiconductor film having a specific resistance value of 0 ¹¹ Ω · cm is attached to a substrate is disclosed. However, in this case, since the semiconductor film is an adhered substance, there is a large possibility that the adhered semiconductor film may be peeled off during the cleaning operation for recovering the dust collection efficiency, or the adhered semiconductor film may be peeled off due to an abnormal discharge phenomenon.

Therefore, an object of the present invention is to provide an electrostatic precipitator capable of suppressing the occurrence of spark discharge as much as possible and having high safety, easy maintenance such as electrode cleaning, and high dust collecting efficiency. To do.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is directed to removing dust in air charged by corona discharge from
1. An electrostatic precipitator that collects dust at a dust collecting part to which an appropriate potential difference is applied between electrodes facing each other at a required interval, wherein the electrode on the low potential side of the dust collector is V on the surface of a metal substrate.
_The gist is that it is formed by coating ceramics containing a divalent metal ion oxide based on the ₂ O ₅ -P ₂ O ₅ system.

[0007]

A structure in which the electrode on the low potential side in the dust collecting portion is made of a metal as a base material, and the surface thereof is coated with ceramics containing a V ₂ O ₅ -P ₂ O ₅ system-based divalent metal ion oxide added thereto. The following actions can be obtained by

(A) The electric field electron emission from the electrode surface on the low potential side is suppressed, the spark discharge generation voltage between the end faces rises, and the probability of abnormal discharge generation in the applied voltage region below the spark discharge generation voltage decreases. To do. In this way, since the spark discharge generation voltage rises, the safety is enhanced and the distance between the electrodes can be narrowed, so that the dust collection efficiency exponentially increases.

(B) V containing a divalent metal ion oxide added
_{Since the 2} O ₅ -P ₂ O ₅ -based ceramic coating film exhibits semiconductivity, the charged dust particles are discharged in a proper time and trapped between the dust collecting electrodes. Therefore, also in this respect, the dust collection efficiency is improved.

(C) The ceramic coating film has excellent peeling resistance and corrosion resistance, and maintenance such as electrode cleaning becomes easy.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

First, the structure of the electrostatic precipitator will be described. As shown in FIG. 1, a charging unit 10 having a discharge electrode 1 and a counter electrode 2 is provided on the upstream side of the flow of air to be purified, and is downstream. Dust collecting part 2 equipped with dust collecting electrode 4 and its counter electrode 5 on the side
0 is provided. Further, in this embodiment, the dust collecting unit 2
Of the two electrodes 4 and 5 in No. 0, the dust collecting electrode 4 on the low potential side is configured as shown in FIG. That is, the dust collecting electrode 4 is composed of a SUS foil 6 having a thickness of about 100 μm as a metal substrate.
On the surface of V ₂ O ₅ (15mo
The ceramic coating film 7 of (1%)-P ₂ O ₅ (80 mol%) is formed in a thickness of 20 to 30 μm by a sol-gel coating method using a metal alkoxide as a starting material.

In FIG. 3, both ends of the dust collecting electrode 4 and the counter electrode 5 thus formed are sandwiched by the collecting electrodes 8 and 9, and the collecting electrodes 8 and 9 are fixed by the insulating supports 11 and 12. Thus, the configuration of the dust collecting portion 20 in which the dust collecting electrode 4 and the counter electrode 5 are arranged to face each other with a required space is shown.

The charging unit 10 is a gold-plated W wire (10
0 μm diameter) discharge electrode 1 and flat plate counter electrode 2 made of SUS-304. Distance between electrodes is 6 mm, applied voltage is 4.2 k.
It operates at about V.

The electrostatic precipitator of this embodiment is constructed as described above, and in the charging section 10 on the upstream side, the discharge electrode 1 is the positive electrode and the counter electrode 2 is the negative electrode.
A high voltage of about kV is applied to generate corona discharge, and the corona discharge charges dust 3 in the air. On the other hand, in the dust collecting portion 20 on the downstream side, a voltage equal to or lower than the applied voltage of the discharging portion 10 is applied between the electrodes 4 and 5 with the counter electrode 5 as a positive electrode and the dust collecting electrode 4 as a negative electrode, and the charged dust 3 is discharged. Are collected by the dust collecting electrode 4.

In such dust collecting operation, V ₂ O ₅ -P ₂ O is formed on the surface of the dust collecting electrode 4 on the low potential side.
_Since the ceramic coating film 7 containing a divalent metal ion oxide based on the ₅ system is formed, the electric field electron emission from the surface of the dust collecting electrode 4 is suppressed, and the spark discharge generation voltage between the end faces increases. At the same time, the probability of abnormal discharge occurrence in the applied voltage region below the spark discharge occurrence voltage decreases. Since the spark discharge generation voltage rises in this way, the distance between the electrodes 4 and 5 of the dust collecting portion 20 can be reduced to about 2 to 3 mm. In the parallel plate type dust collecting part, the dust collecting efficiency increases exponentially as the distance between the electrodes is narrowed. On the other hand, as is clear from FIG. 4, the electrodes 4, 5
Even if the distance between them is reduced to about 1.5 mm, the pressure loss is 0.5.
It can be kept below mmAq. Further, for example, even if the distance between the electrodes 4 and 5 is reduced from 5 to 6 mm to 2 to 3 mm as described above, the pressure loss of ventilation is hardly increased and the dust collection efficiency can be improved.

V containing a divalent metal ion oxide added
_{Since the 2} O ₅ -P ₂ O ₅ -based ceramic coating film 7 exhibits semiconductivity, the charged dust 3 is discharged in a proper time and captured on the surface of the dust collecting electrode 4. Therefore, also in this respect, the dust collection efficiency is improved.

Next, characteristics such as spark discharge starting voltage and dust collection efficiency will be described in comparison with a comparative example.

In Comparative Example 1, a SUS foil without any surface treatment was used for the dust collecting electrode, and in Comparative Example 2, a polymer film (polypropylene) coated with a conductive carbon black-containing coating material and dried was used. A device having the same dust collecting structure as that of the example was produced. The same charging unit as in the embodiment is used.

Table 1 shows the spark discharge starting voltage, the spark discharge starting electrode distance, and the constant electrode distance (2 mm) of the electrostatic precipitators equipped with the dust collecting portions of these Examples and Comparative Examples 1 and 2. The dust collection efficiency at the maximum applied voltage without spark discharge and the pressure loss at that time are shown.

[0021]

[Table 1]

In the examples, the spark discharge inception voltage (distance between electrodes 2 mm), which is a measure of safety, is higher than that in any of Comparative Examples 1 and 2, and the minimum electrode-to-interelectrode spark generation at the same applied voltage of 3 kV. The distance is smaller than that of the two comparative examples 1 and 2. On the other hand, the dust collection efficiency (measured at the atmospheric dust level) at the maximum upper limit applied voltage at which the distance between the electrodes is fixed to 2 mm and the spark discharge does not occur is much higher than 50% in the embodiment,
In Comparative Examples 1 and 2, both are less than 50%. Particularly, in Comparative Example 1 in which the SUS foil without any surface treatment is used for the dust collecting electrode, both safety and dust collecting efficiency have practical problems.

In the above embodiment, the material of the metal substrate of the dust collecting electrode is not limited to the SUS foil. Further, the method of forming the V ₂ O ₅ —P ₂ O ₅ system ceramic coating film to which the divalent metal ion oxide is added is not limited to the method of this embodiment, and may be a method such as sputtering or vapor deposition. is there.

[0024]

As described above, according to the present invention, the electrode on the low potential side in the dust collecting portion is a divalent metal based on the V ₂ O ₅ -P ₂ O ₅ system on the surface of the metal substrate. Since the structure is coated with ceramics containing ionic oxides, the field electron emission from the electrode surface is suppressed, the spark discharge generation voltage rises, safety can be improved, and the distance between electrodes can be narrowed. Therefore, the dust collection efficiency is improved. In addition, since the V ₂ O ₅ -P ₂ O ₅ system ceramic coating film to which the divalent metal ion oxide is added exhibits semiconductivity, the charged dust particles are discharged on the dust collecting electrode surface in an appropriate time. To be captured. Therefore, also in this respect, the dust collection efficiency is improved. Further, the ceramic coating film has excellent peeling resistance and corrosion resistance, and maintenance such as electrode cleaning becomes easy.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of an embodiment of an electrostatic precipitator according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a dust collecting electrode in this embodiment.

FIG. 3 is a perspective view showing an example of an electrode holding method of a dust collecting portion in the present embodiment.

FIG. 4 is a characteristic diagram showing a relationship between a distance between electrodes of a dust collecting portion and pressure loss in the present embodiment.

[Explanation of symbols]

 4 Dust collecting electrode 5 Counter electrode 6 SUS foil (metal substrate) 7 Ceramic coating film 10 Charging part 20 Dust collecting part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Yamaguchi 3-3-9 Shimbashi, Minato-ku, Tokyo Toshiba Abu E. Co., Ltd.

Claims (1)

[Claims] 1. Dust in air charged by corona discharge,
An electrostatic precipitator that collects dust at a dust collecting portion provided with an appropriate potential difference between electrodes facing each other at a required interval, wherein the electrode on the low potential side in the dust collecting portion has a V _{2 on} the surface of a metal substrate. An electrostatic precipitator characterized by being formed by coating ceramics containing a divalent metal ion oxide based on the O ₅ -P ₂ O ₅ system.