JP3339114B2 - High voltage electrode structure of ozone generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage electrode structure of a silent discharge type ozone generator used for water treatment or human waste treatment.

[0002]

2. Description of the Related Art Ozone has an extremely strong oxidizing power and is used for many purposes such as water and sewage treatment such as sterilization, deodorization and decolorization of water, human waste treatment and sterilization in foods. Ozone generation methods include ultraviolet irradiation, radiation irradiation, plasma discharge, silent discharge, and water electrolysis.
Industrially, the silent discharge method is mainly used. FIG. 2 shows the principle of an ozone generator using a silent discharge method. In FIG. 2, the high-voltage electrode 1 and the ground electrode 2 are juxtaposed with a dielectric 4 interposed therebetween so that a gap 3 is formed therebetween. For example, a gas (dry air or oxygen) is generated by applying an AC voltage between the two electrodes 1 and 2 to generate a silent discharge in the gap 3 and serve as a raw material.
Is passed through the gap 3 to generate ozone.

The theoretical yield of ozone O ₃ is as follows: O ₂ → O + O-118 Kcal (endothermic reaction) O + O ₂ → O ₃ +25 Kcal (exothermic reaction) 3O ₂ → 2O ₃ -68 Kcal, and 1 mol of O ₃ Requires 34 Kcal. Therefore, the theoretical yield is 1.2 kg O ₃ / KW
h. However, the efficiency of ozone generation with respect to power consumption is extremely low compared to the theoretical yield, and is only a few percent.
It is the current state of the ozone generator that 0% or more of the electric power does not contribute to ozone generation as heat.

[0004]

The main factors affecting the amount of ozone generated include the shape of the electrode, the size of the gap between the electrodes, the shape and material of the dielectric, the method of cooling the electrode,
Examples include the method of dehumidifying and cooling the source gas, the waveform of the applied voltage, and the like.

As shown in FIG. 2, the current ozone generator has a structure in which a dielectric is interposed so that a gap is formed between the electrodes, and a silent discharge in which a discharge is generated in the gap is applied. Has become the Lord. In order to generate a stable silent discharge, it is necessary to reduce the gap length between the electrodes to several mm or less and make the gap length uniform so that the discharge is generated uniformly in the gap portion. FIG. 1 shows an example of the structure of the electrode portion of an actual ozone generator.

In FIG. 1, (a) is a cross section of the discharge tube,
(B) shows the structure of the dielectric tube. Reference numeral 14 denotes a cylindrical dielectric tube having one end closed and the other end open , and is formed of, for example, a glass tube. The high voltage electrode 1 is provided on the inner wall surface of the dielectric tube 14. The ground electrode 2 is juxtaposed around a concentric outer circumference of the dielectric tube 14 via a gap (silent discharge portion) 3. Reference numeral 5 denotes a high voltage power supply for applying a predetermined high voltage between the high voltage electrode 1 and the ground electrode 2.

In the structure shown in FIG. 1, the reliability of the high-voltage electrode 1 provided inside the dielectric tube 14 serving as a high-voltage electrode is important in order to generate a stable and uniform discharge. FIG.
For producing a high-voltage electrode film for an ozone discharge tube as described above, a method of applying a paint mixed with carbon or spraying aluminum powder is generally used.

There is no problem when these electrode films are in contact with the dry raw material air gas, but when they come into contact with moist outside air, the electrode films are deteriorated (because of the structure shown in FIG. 1).
Since the other end of the dielectric tube 14 is open,
The raw material air gas and outside air flowing through the part 3 contact the electrode coating.
Touchable structure) . That is, nitrogen molecules N ₂ * (active species) excited from the nitrogen molecules N ₂ by the discharge are generated, and nitrogen oxides such as N ₂ O, NO... Among them, N ₂ O ₅ becomes liquid and reacts with the moisture in the humid outside air which enters when the operation of the apparatus is stopped and the tank door is opened, to form nitric acid. When this nitric acid adheres to the sprayed aluminum coating electrode, the aluminum is corroded and the high-voltage electrode coating is deteriorated, resulting in a problem that the glass discharge tube is finally broken.

The present invention has been made in view of the above points, and an object of the present invention is to provide a high-voltage electrode structure of an ozone generator having excellent corrosion resistance without impairing adhesion to a dielectric tube. is there.

[0010]

SUMMARY OF THE INVENTION The present invention comprises a dielectric provided with a high voltage electrode, and a ground electrode provided opposite the dielectric via a gap, wherein the high voltage electrode is connected to a ground. and by applying a voltage between the electrodes kept <br/> ozone generator of the silent discharge type ozone is generated in the raw material gas was passed through inside the gap portion, the thermal spraying of aluminum film on the dielectric to high voltage after forming the electrodes, characterized in that formed by a predetermined means Ni-Cr coating (e.g. spray) on the high voltage electrode
ing.

[0011]

[Action]

(1) Since the Ni-Cr film is formed on the high voltage electrode, the aluminum sprayed film having good adhesion to the glass tube used for the dielectric does not come into direct contact with nitric acid. Ni-C
r has excellent corrosion resistance such as ozone resistance and nitric acid resistance. Therefore, a high-voltage electrode having excellent corrosion resistance can be formed while maintaining the adhesion with the dielectric by the aluminum spray coating.

[0012]

[0013]

An embodiment of the present invention will be described below with reference to the drawings. In the present invention, in order to solve the above-mentioned problem, a structure is adopted in which an aluminum sprayed coating having good adhesion to a glass tube used as a dielectric does not come into direct contact with nitric acid.

That is, in the first and second aspects of the present invention,
Ni-C with excellent corrosion resistance such as ozone resistance and nitric acid resistance
r is sprayed from above the aluminum sprayed coating high voltage electrode 1 shown in FIG. The thermal spraying conditions of Ni-Cr are as follows.

Particle size distribution of Ni—Cr particles: 44 μm or less Sprayed thickness of Ni—Cr: about 50 μm While maintaining the adhesion to the underlying glass tube by the aluminum spray coating, the Ni—Cr spray coating provides It has become possible to form a high-voltage electrode excellent in corrosiveness. When Ni-Cr is directly sprayed on glass, the adhesion of the coating is not as good as that of aluminum.

[0016]

[0017]

[0018]

As described above, according to the first and second aspects of the present invention, after a high voltage electrode is formed by spraying an aluminum film on a dielectric, a Ni-Cr film is formed on the high voltage electrode. Since it is formed by thermal spraying, the following excellent effects can be obtained. (1) Corrosion resistance such as ozone resistance and nitric acid resistance could be improved by applying a Ni-Cr sprayed coating on a conventional aluminum sprayed coating electrode.

[0019]

(2) The high-voltage electrode of the present invention and the underlying dielectric tube (eg, a glass tube) are in contact with each other by an aluminum sprayed film, and have good adhesion. It has become possible to manufacture a discharge electrode for generating ozone having excellent corrosion resistance without impairing the adhesion. (3) Because the reliability of the high-voltage electrode part of the dielectric tube has been improved,
The large-capacity ozone generator can be operated safely, and the ozonized gas can be supplied stably.

[Brief description of the drawings]

1A and 1B schematically show a discharge tube used in an ozone generator of the present invention, wherein FIG. 1A is a sectional view of a discharge tube, and FIG. 1B is a structural diagram of a dielectric tube.

FIG. 2 is an explanatory diagram showing the principle of ozone generation by a silent discharge method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... High voltage electrode 2 ... Ground electrode 3 ... Void part 4 ... Dielectric 5 ... High voltage power supply 14 ... Dielectric tube

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-88702 (JP, A) JP-A-3-269980 (JP, A) JP-A-56-3242 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) C01B 13/11

Claims (2)

(57) [Claims] 1. One end is closed and the other end is open, and
A dielectric tube high voltage electrode is provided in the wall, and a ground electrode which is arranged facing with a gap portion in the dielectric tube, wherein a voltage is applied between the high voltage electrode and the ground electrode In a silent discharge type ozone generator that generates ozone in the raw material gas circulated in the gap, a high voltage electrode is formed by spraying an aluminum film on the inner wall of the dielectric tube, and then forming the high voltage electrode on the high voltage electrode. A high voltage electrode structure for an ozone generator, wherein a Ni-Cr coating is formed by a predetermined means. 2. The high voltage electrode structure of an ozone generator according to claim 1, wherein said predetermined means is formed by thermal spraying.