JPH1193644A - Corona generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently wash a deposit to a surface of an electrode by providing a first electrode having a projecting part in a surface thereof and a second electrode provided opposite to the first electrode, and forming a surface of one of both the electrodes of an optical catalyst body for receiving the ultraviolet rays generated by corona discharge so as to realize the hydrophilicity. SOLUTION: In a brush corona generator 5 to be used as a harmful gas dissociating and eliminating device for dissociating the harmful gas in the exhaust gas of automobile for elimination, an electrode 1 formed with a projecting part for generating the brush corona in a surface thereof is supported by a support 6 at a central part of an insulating part 3, and an electrode 2 is fitted to an outer wall of the insulating part 3. Both the electrodes 1, 2 are coated with optical catalyst material 12, 31 on a surface thereof. In this case, the optical catalyst material 12, 31 are formed of a member for receiving the ultraviolet rays generated by corona discharge so as to realize the hydrophilicity, preferably, a material mainly composed of titanium oxide. These electrodes 1, 2 are electrically connected to each other through a high-voltage power source 4 as a circuit for generating high voltage of a positive and a negative electrodes at the predetermined frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification technique for removing harmful substances such as nitrogen oxides (NOx) contained in exhaust gas discharged from various combustors such as an engine and a boiler of an automobile. It is related to the improvement of.

[0002]

2. Description of the Related Art In recent years, air pollution due to NOx or the like has become a problem, and the development of purification technology for exhaust gas discharged from various combustors has been promoted. For example, in a gasoline engine automobile, a three-way catalyst method or the like is used, and research on improving catalysts and systems is being advanced. On the other hand, lean-burn engines have been developed to improve fuel efficiency. However, in this case, since the air-fuel ratio is high, a large amount of oxygen remains in the exhaust gas, making it difficult to effectively remove NOx. ing. As a prior art for removing such NOx and the like, there is, for example, a technique disclosed in Japanese Patent Application Laid-Open No. H8-24562. Although this shows a deodorizing apparatus using discharge plasma, it was an effective technique for removing NOx and the like. However, "soot", which inhibits the generation of brush corona, which is a type of discharge plasma, tends to adhere to the surface of the electrode that generates the discharge plasma. The washing liquid was always dropped.

[0003]

However, in many cases, the surface of the electrode is hydrophobic, so that water does not get used to the electrode and it is not possible to sufficiently clean the deposits on the electrode surface. The present invention has been made in view of the above problems, and has as its object to provide an effective means for keeping the surface of an electrode hydrophilic.

[0004]

The present invention provides the following means to achieve the above object. First, the invention according to claim 1 includes a first electrode having a convex portion connected to the surface, a second electrode provided to face the first electrode, an insulating portion attached to the second electrode, In a corona generating device provided with a high-voltage power supply connected between the two electrodes, a corona generating device comprising a photocatalyst in which at least one surface of the two electrodes receives ultraviolet light generated by corona discharge to exhibit hydrophilicity. I do.

[0005] The invention according to claim 2 provides a corona generator in which the photocatalyst is made of a material mainly composed of titanium oxide.

According to a third aspect of the present invention, there is provided a corona generator in which at least one of the two electrodes is made of a photocatalyst.

[0007]

Embodiments of the present invention will be described with reference to the accompanying drawings. In this embodiment, an example in which the present invention is applied to an apparatus for dissociating and removing harmful gas in exhaust gas from automobiles will be described. In FIG. 1, reference numeral 7 denotes a combustor for an automobile engine or the like, 5 denotes a brush corona generator, 8 denotes a catalytic reactor, 10 denotes a silencer, and 9 denotes an exhaust gas pipe. Thus, the exhaust gas port 7 a of the combustor 7 is connected to the catalytic reactor 8 via the brush corona generator 5.

FIG. 2 is a vertical sectional view of the scraper corona generator 5. In the brush type corona generator 5, the first electrode 1
Is, for example, a rod made of conductive material processed into a screw shape. The first electrode 1 can form a projection 11 having a triangular cross section as shown in FIG. 3 or a projection 11 having a trapezoidal cross section as shown in FIG. 4 by changing the thread pitch.

The protrusion 11 is provided with the brush corona generator 5.
This is for generating a spreader corona in a wide range within the inside, and may have another shape, for example, a protrusion provided at a key point on the surface of the first electrode 1.

The first electrode 1 is supported by a support 6 at the center of the insulating section 3. The insulating portion 3 is formed in a cylindrical shape from an insulating material such as ceramics or organic glass, and has the second electrode 2 attached to an outer wall thereof. The attaching means first forms a second electrode 2 by printing a metal paste on the surface of the insulating portion 3 such as a ceramic and baking the paste. Note that the insulating portion 3 may be formed by forming the second electrode 2 in advance with a metal pipe and applying enamel processing to the surface thereof with organic glass.

The two electrodes 1 and 2 have photocatalysts 12 and 31 attached to their surfaces. The photocatalysts 12, 31 are
A member that manifests hydrophilicity by receiving ultraviolet rays generated by corona discharge, and is made of a material mainly composed of titanium oxide. The photocatalysts 12 and 31 are manufactured by "O plus E, N" issued by Shin Technology Communications Co., Ltd.
o. 211, page 75 to page 81, "Special Feature: Exploring Possibilities of Photocatalyst". This property is referred to as "superhydrophilicity."), And the superhydrophilicity lasts for several hours to about one hour even after the ultraviolet irradiation is stopped.

It is well known that ultraviolet light is generated by corona discharge. When corona discharge occurs in both electrodes 1 and 2, the ultraviolet light generated thereby adheres to the surfaces of both electrodes 1 and 2. The photocatalysts 12 and 31 are irradiated. As a result, the surfaces of the two electrodes 1 and 2 become superhydrophilic, and the moisture in the exhaust gas A introduced into the brush corona generator 5 adheres to the surfaces of the two electrodes 1 and 2, as a result.
The soot and the like adhering to the surfaces of the electrodes 1 and 2 are washed away by the adhered water.

Although the photocatalysts 12 and 31 are attached to the surfaces of the electrodes 1 and 2 as described above, the electrodes 1 and 2 themselves may be constituted by the photocatalysts 12 and 31.

The first electrode 1 and the second electrode 2 are electrically connected via a high-voltage power supply 4. The high-voltage power supply 4
A circuit that generates both positive and negative high voltages at a certain frequency,
The waveform may be any of a sine wave and a pulse wave. The frequency may be constant or may be a frequency synchronized with the engine speed such as the output of an ignition coil.

The scraper corona generator 5 having the above structure is shown in FIGS.
A brush corona is generated according to the principle shown in FIG. That is, when a high voltage is applied between the first electrode 1 and the second electrode 2 by the high-voltage power supply 4, a brush corona is formed between the insulating portion 3 attached to the inner surface of the second electrode 2 and the first electrode 1. Occur.

FIG. 5 shows a state in which a positive voltage is applied to the first electrode 1 and a negative voltage is applied to the second electrode 2 by the high voltage power supply 4. 5 indicate the direction of an electric field generated by the high voltage applied between the first electrode 1 and the second electrode 2, and the arrow indicated by the symbol ES is accumulated on the surface of the insulating part 3. The symbol P indicates the direction of the reverse electric field generated by the charge, the symbol P indicates the positive charge accumulated on the surface of the insulating portion 3, and the symbol C1 indicates the positive corona. FIG. 5 particularly shows the softening corona in which the positive corona has grown most.

In the state shown in FIG. 5, the spreader corona C1
Is generated, the positive charge P is accumulated on the surface of the insulating portion 3, and the reverse charge ES increases in accordance with the amount of the positive charge P, thereby suppressing the duster corona C1. It changes to a brush corona or a film corona which occurs only near one electrode 1. The change attenuation phenomenon of the brush corona C1 is eventually caused by the positive charge P
This is caused by the fact that the accumulated amount of P has become too large, and by taking measures to reduce the excess positive charge P, the coring corona C1 can increase and grow. In this embodiment, by neutralizing and reducing the excess positive charge P through the steps shown in FIGS. 6 and 7 described below,
The occurrence of the brush corona C1 is ensured.

FIG. 6 shows a state where the polarity of the output of the high-voltage power supply 4 is switched, that is, a state of a so-called zero point. In the state shown in FIG. 6, the generation of the corona temporarily stops. FIG.
5 shows a state in which a negative voltage is applied to the first electrode 1 and a positive voltage is applied to the second electrode 2 by the high-voltage power supply 4. The symbol e in FIG. 7 indicates an electron, and the symbol C2 indicates a negative corona. In the state shown in FIG. 7, a negative corona C2 and an electron e are generated from the first electrode 1, and the electron e is combined with the positive charge P accumulated on the surface of the insulating portion 3 and neutralized. As a result, the excess positive charge P is reduced, and when the state again proceeds to the state shown in FIG. 5, the scraper corona C1 can be generated. As described above, the continuous generation of the scraper corona C1 is maintained by repeating the states shown in FIGS.

According to an experiment, an alternating current having a frequency of 50 Hz was boosted to 10 to 15 [KV] by the high-voltage power supply 4 shown in FIG. 1 and applied between the first electrode 1 and the second electrode 2.
A large-scale corona discharge phenomenon was induced and observed over a wide area. In addition, it was confirmed that the obtained brush core corona was also stably maintained without attenuation. The same operation was obtained even when the voltage applied between the electrodes 1 and 2 from the high voltage power supply 4 was DC instead of AC.

Next, the operation of the corona generator having the above configuration will be described. First, the exhaust gas A discharged from the combustor 7 is introduced into the scraper corona generator 5. In a space formed between the first electrode 1 and the insulating portion 3 of the brush corona generator 5, a large-scale brush corona C1 is generated, and when the exhaust gas A passes through this space, NOx or The harmful gas such as SOx is activated by the action of the scraper corona, and is discharged as dissociated exhaust gas B. Then, the exhaust gas B that has passed through the scraper corona generator 5 is introduced into the catalytic reactor 8, and NOx and SOx are finally removed by the catalytic layer 8a.

[0021]

The present invention has the following effects. That is, the present invention provides a first electrode having a convex portion connected to a surface, a second electrode provided to face the first electrode, an insulating portion attached to the second electrode, In a corona generator provided with a high-voltage power supply connected between, at least one surface of the two electrodes receives ultraviolet rays generated by corona discharge, from a photocatalyst of a material mainly composed of titanium oxide that exhibits hydrophilicity. Since the corona generating device is provided, it is possible to provide an effective means for keeping the surface of the electrode hydrophilic, and it is possible to sufficiently clean the deposits on the electrode surface. In addition, the ultraviolet rays to be irradiated on the photocatalyst can be easily obtained by corona discharge used for purifying exhaust gas. In other words, there is an effect that a dedicated device is not required for ultraviolet irradiation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the scraper corona generator shown in FIG.

FIG. 3 is a perspective view of a main part in which a triangular projection is formed on the surface of the first electrode shown in FIG. 2;

FIG. 4 is a perspective view of a main part in which a trapezoidal projection is formed on the surface of the first electrode shown in FIG. 2;

FIG. 5 is an explanatory diagram illustrating a positive corona generating state in the brush corona generator shown in FIG. 2;

FIG. 6 is an explanatory diagram illustrating a zero point state in the scraper corona generator illustrated in FIG. 2;

FIG. 7 is an explanatory diagram illustrating a negative corona generating state in the brush corona generator illustrated in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st electrode 2 2nd electrode 3 Insulation part 4 High voltage power supply 5 Spread corona generator 12, 31 Photocatalyst

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01T 19/04 H01T 19/04

Claims (3)

[Claims] 1. A first electrode (1) having a convex portion (11) connected to a surface thereof, a second electrode (2) provided to face the first electrode (1), and the second electrode. In a corona generator provided with an insulating portion (3) attached to (2) and a high-voltage power supply (4) connected between the electrodes (1, 2), at least one of the electrodes (1, 2) is provided. A photocatalyst (1) that has one surface exposed to ultraviolet light generated by corona discharge to exhibit hydrophilicity
2, 31) a corona generator. 2. The corona generating apparatus according to claim 1, wherein the photocatalyst (12, 31) is made of a material mainly composed of titanium oxide. 3. The corona generator according to claim 1, wherein at least one of the electrodes (1, 2) is made of a photocatalyst (12, 31).