JP2000226202A - Tubular ozonizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically decrease a discharge gap amount by using a small- diameter glass tube having a specific outer diameter as a ring-shaped dielectric substance. SOLUTION: Cooling water is circulated through a metal tank 10 and a raw material gas is circulated through a discharge gap 50 of each cell module. A fixed high voltage is impressed to an inner electrode 40 of each cell module in this state, a silent discharge is generated in the discharge gap 50 and the raw material gas is ozonized. An outside electrode 20 brought into contact with the discharge gap 50 from the outside is composed of a stainless steel pipe and the accuracy of its inner diameter is <=0.3 mm tolerance to be high. On the other hand, since a small-diameter glass tube 30 brought into contact with the discharge gap 50 is sold in the market and has <=20 mm outer diameter, the accuracy of the outer diameter is <=0.3 mm tolerance to be high. Consequently, a gap amount G of the discharge gap 50 can be reduced to <=0.6 mm and the tolerance can be satisfied. Therefore, high-concentration ozone can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tubular ozone generator.

[0002]

2. Description of the Related Art Ozone generators are roughly classified into a plate type and a tube type according to the basic shape of a discharge cell. In a conventional typical tubular ozone generator, as shown in FIG. 3, a plurality of metal pipes penetrating both end plates between end plates 2 and 2 closing both end openings of a cylindrical metal tank 1. .. Are installed in parallel. Each metal tube 3 is a low-voltage electrode, and discharge is caused by a tubular dielectric 4 inserted into the inside of the metal tube 3 with a gap therebetween, and a tubular high-voltage electrode 5 provided inside the dielectric 4 in contact with its inner peripheral surface. An annular discharge gap 6 between the element and the dielectric 4.
To form A closing portion 7 is formed at one end of the dielectric 4 by molding to prevent the flow of the raw material gas into the inside.

When ozone is generated, discharge gaps 6, 6,... Formed on the inner surface side of a plurality of low-voltage electrodes 3, 3,.
Then, the raw material gas is circulated from the one end plate 2 side in parallel. The source gas is oxygen gas or a mixed gas containing oxygen gas. In addition, cooling water is circulated in the metal tank 1. In this state, the dielectrics 4, 4,.
A predetermined high voltage is applied to 5... To generate silent discharge in the discharge gaps 6, 6,. As a result, the raw material gas is exposed to silent discharge while passing through each discharge gap 6 to be ozonized, and is taken out to the other end plate 2 as ozone gas.

As the annular dielectric 4 used in such a tube-type ozone generator, a glass tube having an outer diameter of 70 to 80 mm is exclusively used. The reason for using a glass tube is that it is easy to form into a tube and is economical, and a relatively high outer diameter accuracy can be easily obtained. In addition, the reason that the outer diameter is set to 70 to 80 mm is that it was considered that it is advantageous to increase the amount of ozone generated per cell unit to generate a large amount of ozone. The reason for the large diameter is that it is disadvantageous in terms of work and handling.

The gap amount G of the discharge gap 6 has been selected to be 1.2 mm or more. However, in recent ozone generators, one of the trends is to reduce the discharge gap G, and the tubular type is no exception. This is because, by reducing the discharge gap amount G, the cooling efficiency of the discharge gap 6 is increased, whereby the concentration of ozone gas can be increased, and a discharge effect suitable for ozone generation can be obtained in relation to the electron energy level. It is said that it is done. For this reason, in a recent tubular ozone generator, the discharge gap amount G is set to 0.6.
mm or less is becoming mainstream.

[0006]

However, in the tubular ozone generator, reducing the discharge gap amount G is accompanied by a significant deterioration in economic efficiency.

That is, when the discharge gap amount G is reduced, the uniformity (gap tolerance) becomes severe. Accordingly, in order to reduce the discharge gap amount G, it is necessary to increase the accuracy of the inner diameter of the low-voltage electrode 3 in contact with the discharge gap 6 and the accuracy of the outer diameter of the glass tube (dielectric 4) also in contact with the discharge gap 6. . Here, regarding the inner diameter accuracy of the low-voltage electrode 3, there is no problem as it is a commercially available product because a stainless steel tube is used as the low-voltage electrode 3, but the outer diameter accuracy of the glass tube is a commercially available product. There is a problem with low accuracy. For this reason, glass tubes used in high-concentration ozone generators of the micro-gap type are made of commercially available products that have been reshaped by heating at high temperatures, and the price of these reshaped glass tubes is extremely high. Is getting higher. In addition, since the glass tube is reheated, there is a concern that the mechanical strength of the glass tube may be reduced due to thermal distortion.

An object of the present invention is to provide a tubular ozone generator capable of economically reducing the discharge gap amount G.

[0009]

SUMMARY OF THE INVENTION A tubular ozone generator according to the present invention comprises a tubular outer electrode, a tubular inner electrode inserted into the outer electrode with a space therebetween, and a tubular inner electrode inserted between both electrodes. A tubular ozone generator comprising a tubular dielectric forming an annular discharge gap with at least one of the electrodes, wherein a small-diameter glass tube having an outer diameter of 20 mm or less is used as the annular dielectric. is there.

[0010] Table 1 shows the relationship among the outer diameter, outer diameter accuracy and wall thickness of commercially available glass tubes. As can be seen from this table, commercially available glass tubes tend to improve the accuracy of the outer diameter as the outer diameter becomes smaller. The outer diameter accuracy that can correspond to the discharge gap amount G of 0.6 mm or less is ± 0.3 mm or less on the glass tube side in consideration of the diameter accuracy of the inner and outer electrodes. If this is used, this outer diameter accuracy can be obtained with a commercially available product. By the way, the outside diameter accuracy of the commercially available glass tube with an outside diameter of 70 to 80 mm is ±
1.3 mm.

[0011]

[Table 1]

In addition, the use of a small diameter glass tube has the following advantages.

When a discharge gap is formed only on the outer surface side of the glass tube, that is, when the inner electrode is in contact with the inner peripheral surface of the glass tube, at least one end of the glass tube is required to prevent gas flow into the tube. Need to be closed. Although a plug is economical as a closing means, in the case of a large-diameter glass tube, there is a possibility that the plug may come off due to a pressure difference between the inside and outside of the tube. Therefore, as shown in FIG. And, cost is required for closing the pipe end by this molding. However, in the case of a small-diameter glass tube, the plug is inserted into the tube end, so that the tube end is closed economically.

When a small-diameter glass tube is used, the amount of ozone generated per element is reduced, but the dead space inside and outside the element is reduced, and the degree of integration is increased. Ozone gas capacity is secured.

When the diameter of the glass tube is reduced, the handleability of the glass tube and the metal tube as the outer electrode is improved, and the welding of both ends of the metal tube to the end plates can be performed easily and economically by a small automatic welding machine. Will be This further reduces the manufacturing cost of the high-concentration ozone generator of the minute gap type.

In the case of a commercially available glass tube, as the outer diameter decreases, the wall thickness also decreases. When the thickness of the glass tube is reduced, the voltage drop in the glass tube is reduced, and the driving voltage can be reduced. By lowering the driving voltage,
The insulation of the discharge element and the step-up transformer of the power supply is also facilitated, and the reliability is improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional side view of a discharge cell unit of a tubular ozone generator according to an embodiment of the present invention, and FIG. 2 is a front view of the discharge cell unit.

The tubular ozone generator according to this embodiment is
A metal tank 10 having a cylindrical shape through which cooling water flows, and a plurality of cylindrical discharge elements provided in parallel inside a cylindrical portion 11 of the metal tank 10 are provided.

Each element is concentric with a tubular outer electrode 20 penetrating the end plates 12 at both ends of the metal tank 10 and extending between the end plates 12, 12 with a gap provided inside the outer electrode 20. A small-diameter glass tube 30 as a dielectric arranged in a shape, and a tubular inner electrode 40 provided in the small-diameter glass tube 30 in contact with the inner peripheral surface thereof are provided.

The tubular outer electrode 20 is a low-pressure electrode made of a stainless steel tube, and both ends are welded around round holes formed in the end plates 12 at both ends of the metal tank 10 so as to form a metal tank 10. It is integrated with. The outer diameter of the outer electrode 20 is reduced with the use of a small-diameter glass tube 30 described later. In addition, the metal tank 10 also has the outer electrode 2.
It is made of stainless steel as in the case of No.

The small-diameter glass tube 30 as a dielectric is made of borosilicate glass, is a commercially available product having an outer diameter of 20 mm or less, and is thin. The small-diameter glass tube 30 is concentrically held in the outer electrode 20 by a spacer (not shown), and forms an annular discharge gap 50 with the outer electrode 20. The gap amount G of the discharge gap 50 is limited to 0.6 mm or less. One end of the small-diameter glass tube 30 is closed by a plug 31 pressed into the end. The material of the plug 31 is a fluororesin.

The annular inner electrode 40 is a high-voltage electrode and, like the outer electrode 20, is made of a stainless steel tube.

The discharge elements having such a configuration are arranged in parallel inside the cylindrical portion 11 of the metal tank 10 with a sufficient degree of integration. Inner electrode 40 of each cell module
The (high-voltage electrode) is connected in parallel to a high-voltage power supply, and the outer electrode 20 (low-voltage electrode) is grounded via the metal tank 10.

When generating ozone, the metal tank 1
Cooling water is circulated in the inside of the cell module, and source gas is circulated in the discharge gap 50 of each cell module. In this state, a predetermined high voltage is applied to the inner electrode 40 (high voltage electrode) of each cell module, and silent discharge is generated in the discharge gap 50. Thus, the source gas flowing through the discharge gap 50 becomes ozone gas.

Here, the gap amount G of the discharge gap 50 is limited to 0.6 mm or less. Since the outer electrode 20 (low-voltage electrode) in contact with the discharge gap 50 from the outside is made of a stainless steel tube, the inner diameter accuracy is as high as 0.3 mm or less. The small-diameter glass tube 30 that is in contact with the discharge gap 50 from the inside is a commercially available product, but since the outer diameter is 20 mm or less, the accuracy of the outer diameter is as high as 0.3 mm or less (Table 1). For these reasons, the gap amount G of 0.6 mm or less satisfies the tolerance, thereby enabling generation of high-concentration ozone.

In addition, since the small diameter glass tube 30 is a commercially available product, it is inexpensive. Further, the end treatment is economically performed by the plug 31, and the welding of the outer electrode 20 (low-voltage electrode) is economically performed by a small welding machine for a small diameter pipe. Therefore, as a high-concentration ozone generator of a small gap type, the manufacturing cost is greatly reduced.

Furthermore, the capacity of the entire ozone generator is sufficiently ensured by increasing the degree of integration of the discharge elements.

The gap amount G of the discharge gap 50 is preferably as small as possible from the viewpoint of increasing the concentration of ozone gas.
mm or less is particularly preferred, but when the glass tube is a commercial product,
Since it is not possible to make it smaller than the accumulated tolerance value of the commercial product,
mm is the lower limit.

In the above embodiment, the discharge gap 50 is formed on the outer surface side of the small-diameter glass tube 30.
Alternatively, it can be formed on the inner and outer surfaces. The inner diameter accuracy of the small diameter glass tube 30 is as good as the outer diameter accuracy.

[0030]

As described above, the tube-type ozone generator of the present invention uses a small-diameter glass tube having an outer diameter of 20 mm or less as a tubular dielectric, so that it is possible to reduce the discharge gap. Gap uniformity can be easily ensured with a commercially available product. Therefore, high-concentration ozone gas can be generated economically.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a discharge cell unit of a tubular ozone generator according to an embodiment of the present invention.

FIG. 2 is a front view of the discharge cell unit.

FIG. 3 is a vertical sectional side view of a discharge cell portion of a conventional tubular ozone generator.

[Explanation of symbols]

 Reference Signs List 10 metal tank 20 outer electrode (low-voltage electrode) 30 small-diameter glass tube 31 plug 40 inner electrode (high-voltage electrode) 50 discharge gap 60 high-voltage power supply

Claims (4)

[Claims] An annular discharge gap is formed between a tubular outer electrode, a tubular inner electrode inserted into the outer electrode with a gap, and at least one electrode inserted between both electrodes. A tubular ozone generator comprising: a tubular dielectric body comprising: a tubular dielectric body, wherein the annular dielectric body is a small-diameter glass tube having an outer diameter of 20 mm or less. 2. The tube-type ozone generator according to claim 1, wherein the small-diameter glass tube is a commercially available product that does not undergo reshaping. 3. The tubular ozone generator according to claim 1, wherein a gap amount G of the discharge gap is 0.6 mm or less. 4. An inner electrode is in contact with the inner peripheral surface of the small-diameter glass tube to form a discharge gap only on the outer surface side of the small-diameter glass tube, and at least one end of the small-diameter glass tube is closed by a plug inserted into the end. The method according to claim 1, wherein
4. The tubular ozone generator according to 2 or 3.