JP3812128B2 - Ozone generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ozone generator, and more particularly to an ozone generator capable of efficiently generating high pressure and high concentration ozone.
[0002]
[Prior art]
FIG. 14 shows a conventional ozone generation called an Otto-Plate (Otto-Plate) type shown in, for example, a publication (“Ozonizer Handbook” of the Society of Electrical Engineers Ozonizer Technical Committee, 1960, published by Corona, page 249). The principal part of an apparatus is shown, (a) is sectional drawing, (b) is a front view of the left half. In the figure, 1 is a power source, 2 is a grounded metal electrode, 3 is a high-voltage electrode provided opposite to the ground electrode 2 and connected to the power source 1 and applied with a high voltage, 4 is a ground electrode 2 and a high-voltage electrode 3. A dielectric (glass plate) 5 is placed on the surface of the substrate, 5 is a discharge space where discharge occurs, and 6 is an electrically insulating (dielectric) spacer for forming the discharge space 5. Reference numerals 7 and 8 denote arrows indicating gas supply and discharge, respectively, and 9 denotes an ozonized gas discharge pipe. The ground electrode 2, the high-voltage electrode 3, and the dielectric 4 arranged between these electrodes constitute one discharge cell.
[0003]
Next, the operation will be described. In the conventional ozone generator, a gas discharge hole is provided in the center of the ground electrode 2, the high voltage electrode 3, and the dielectric plate 4. In the above-mentioned Otto plate type document, there is no description about the spacer 6, but as shown in FIG. 14, the gap between the dielectrics 4, 4 is actually maintained so as not to obstruct gas inflow. An electrically insulating spacer is installed around the discharge space 5 in such a shape.
Source gas containing oxygen is introduced in the direction of arrow 7 from the entire periphery of the ozone generator, and a part of oxygen is passed through the discharge space 5 where a high voltage is applied by the power supply device 1 and discharged. The gas containing ozone is extracted as ozonized gas in the direction of arrow 8 through the central gas discharge pipe 9.
[0004]
Since the discharge space 5 generates heat due to discharge, the gas temperature in the discharge space 5 rises and the amount of ozone generated decreases unless the gas passing through the discharge space 5 is effectively cooled. Therefore, the ground electrode 2 and the high-voltage electrode 3 are cooled with a liquid having electrical insulation properties such as insulating oil to suppress an increase in gas temperature.
Japanese Patent Application Laid-Open No. 8-133704 discloses a plate type ozone generator in which a cooling chamber for passing cooling water is provided on the back surface of an electrode.
[0005]
[Problems to be solved by the invention]
Conventional ozone generators are configured as described above. Under high pressure, the electrodes are distorted, and the gap length cannot be maintained accurately. Where the gap length is long and where the gap length is short, a larger amount of source gas flows when the gap length is longer. However, since the energy given to the source gas is larger when the gap length is shorter, the energy cannot be efficiently given to the source gas, and high-pressure and high-concentration ozone cannot be generated.
In addition, in the above-mentioned Japanese Patent Application Laid-Open No. 8-133704, it is described that at least one column made of quartz or glass material is provided in the discharge gap in order to keep the gap length uniform. Under high pressure, the electrode is likely to be recessed toward the cooling chamber. Further, since the support is provided in the discharge gap, there is a problem in that the discharge area is reduced and the discharge is adversely affected.
[0006]
The present invention has been made to solve the above-mentioned problems of the prior art, and can maintain the gap length with high accuracy even in high pressure, and efficiently obtain high pressure and high concentration ozone. It is an object of the present invention to provide an ozone generator that can be used.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an ozone generator that is disposed opposite to each other with a dielectric interposed between them, two electrodes that cause a discharge when a high voltage is applied therebetween, and a back surface of at least one of the electrodes. A cooling chamber provided in the cooling chamber, a refrigerant supply mechanism for supplying a refrigerant to the cooling chamber, a gas supply mechanism for supplying a gas containing oxygen between the electrodes, and the one electrode provided inside the cooling chamber. And a reinforcing member that supports a region facing the other electrode from the back surface .
[0008]
According to a second aspect of the present invention, in the first aspect of the invention, the refrigerant flow path is formed by the reinforcing member .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a configuration of an ozone generator according to Embodiment 1 of the present invention. In the figure, 1 is a power source and 2 is a grounded metal electrode. In this example, a cooling chamber 100 is integrally provided on the back surface of the ground electrode 2. Reference numeral 3 denotes a high voltage electrode, and 4 denotes a dielectric interposed between the electrodes. In this example, the high voltage electrode 3 is provided with a dielectric 4. 5 is a discharge space, 6 is an electrically insulating spacer for forming the discharge space 5, 7 and 8 are arrows indicating supply and discharge of gas, 9 is a discharge tube for ozonized gas, 10 is a pressure vessel, 11 , 12 respectively use a coolant supply port and a discharge port, and in this example, for example, water as the coolant. Reference numeral 13 denotes a pump for conveying cooling water, and reference numeral 14 denotes a water storage tank capable of maintaining the cooling water at a predetermined temperature, for example, 15 ° C. As the electrodes 2 and 3, for example, disc-shaped ones having a diameter of 200 mm are used, and the distance between the grounded metal electrode 2 and the dielectric 4, that is, the gap length is, for example, 50 μm. Further, the electrode 2 provided with the cooling chamber 100 on the back surface is preferably formed as thin as possible in order to increase the heat exchange efficiency, and is, for example, 5 mm thick.
[0015]
In such a configuration, as shown by an arrow 7, a source gas containing oxygen such as oxygen, air, or a mixed gas of oxygen and nitrogen is introduced into the pressure vessel 10 by a gas supply mechanism (not shown). A part of oxygen becomes ozone when passing through the discharge space 5 which is a space between the electrodes 2 and 3 which is supplied at a preset pressure and applied with a high voltage by the power source 1 and is discharged. The gas is taken out in the direction of arrow 8 through the central gas discharge pipe 9 as ozonized gas. In order to suppress the temperature of the electrode from rising due to the discharge, cooling water is sent from the water storage tank 14 to the cooling chamber 100 by the pump 13 for conveying the cooling water. The ground electrode 2 tends to be distorted due to a pressure difference between the discharge space 5 and the cooling chamber 100, but the cooling water is fed by the pump 13 so that the pressure becomes approximately equal to the pressure of the supply gas. It is possible to prevent distortion and maintain the gap length with high accuracy.
[0016]
FIG. 2 is an example of an experimental result using the ozone generator of FIG. 1, and is a graph showing the ozone generation characteristics when the raw material gas supply pressure is 1.7 atm to 10.0 atm. The horizontal axis represents the energy W / Q _N (W · min / _N 1; the subscript N represents the standard state STP) input per molecule of the raw material gas, and the vertical axis represents the ozone generation efficiency η (mg / ( W · min)).
Oxygen is supplied as a source gas, 1 W of discharge power is applied per 1 cm ^{2 of} discharge area, and the supply gas pressure (absolute pressure) is changed to 1.7 atm, 2.5 atm, 5.0 atm, 7.5 atm, 10.0 atm. It has been made. The cooling water pressure in the cooling chamber 100 was adjusted by the cooling water transfer pump 13 so as to be the same as the supply gas pressure.
From this experimental result, it can be seen that in the apparatus according to the first embodiment shown in FIG. 1, the ozone generation efficiency increases as the pressure increases as shown in FIG. 2 by maintaining the gap length with high accuracy. .
[0017]
FIG. 3 is an example of the experimental results using the ozone generator of FIG. 1, and the discharge gap length and the maximum concentration of generated ozone when the discharge density W / S obtained by dividing the discharge power by the discharge area is 1 W / cm ^2. This represents the relationship. The horizontal axis represents the discharge gap length d (mm), and the vertical axis represents the maximum ozone concentration generated (both values near W / Q _N = 300 W · min / _N 1). As shown in this figure, it is understood that the discharge gap length needs to be 0.5 mm or less in order to obtain an ozone concentration of 200 g / _N m ³ or more under a high pressure of 10 atm.
[0018]
Embodiment 2. FIG.
4A and 4B show an ozone generator according to Embodiment 2 of the present invention. FIG. 4A is a cross-sectional view showing the overall configuration, and FIG. 4B is a block diagram of signal processing. The same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. In the figure, 15 is a pressure sensor for measuring the gas pressure in the ozone generating container 10, and 16 is a pressure sensor for measuring the water pressure of cooling water. Examples of these pressure sensors include strain gauge pressure transducers and semiconductor pressure converters. A vessel or the like is used. 17 is a pump pressure control device, and 18 is a comparator.
The outputs from the gas pressure sensor 15 and the water pressure sensor 16 are taken into the comparator 18 and the pump 13 is controlled by the pump pressure control device 17 so that the pressure difference between the two inputs is eliminated.
Since the sensors 15 and 16 are easily attached, the gas pressure between the electrodes 2 and 3 is discharged from the cooling chamber 100 at the peripheral portion in the pressure vessel 10 and the water pressure in the cooling chamber 100 is returned to the water storage tank 14. Measurements were made on the way.
[0019]
Thus, since the water pressure is changed by changing the pump pressure while monitoring the gas pressure, it is possible to efficiently generate ozone by preventing the electrode from being distorted by the gas pressure. Even if the gas pressure changes during the generation of ozone, if the gas pressure is constantly monitored, there is no change in the discharge gap length due to the distortion of the electrode 2, and a decrease in ozone generation efficiency can be prevented.
[0020]
Embodiment 3 FIG.
5A and 5B show an ozone generator according to Embodiment 3 of the present invention, in which FIG. 5A is a sectional view showing the overall configuration, and FIG. 5B is a block diagram of signal processing. In the figure, 19 is a valve.
The outputs from the pressure sensor 15 for measuring the gas pressure in the ozone generation container 10 and the pressure sensor 16 for measuring the water pressure of the cooling water are taken into the comparator 18 so that the pressure difference between the two inputs is eliminated. The water pressure is controlled by adjusting the opening and closing.
[0021]
Thus, since the water pressure is changed by adjusting the valve 19 while monitoring the gas pressure, the distortion of the electrode 2 due to the gas pressure can be prevented and ozone can be generated efficiently. Even if the gas pressure changes during the generation of ozone, if the gas pressure is constantly monitored, there is no change in the discharge gap length due to the distortion of the electrode 2, and a decrease in ozone generation efficiency can be prevented.
[0022]
Embodiment 4 FIG.
FIG. 6 is a cross-sectional view showing an overall configuration of an ozone generator according to Embodiment 4 of the present invention. In the present embodiment, instead of measuring the gas pressure and the water pressure by the pressure sensors 15 and 16 in the second embodiment shown in FIG. 4, the piezoelectric element 20 is disposed on the cooling chamber 100 side of the ground electrode 2, and the ground electrode 2 is measured, and the pump 13 is controlled by the pump pressure control device 17 so that the distortion is eliminated.
Also in the present embodiment, since the change in the differential pressure between the gas pressure and the water pressure is monitored by the piezoelectric element 20, the same effect as in the second embodiment can be obtained. Furthermore, the number of parts is small and inexpensive compared to the second embodiment.
Instead of adjusting the supply pressure of the pump 13, the opening and closing of the valve 19 may be adjusted in the same manner as in the third embodiment shown in FIG.
[0023]
Embodiment 5 FIG.
FIG. 7 shows an ozone generator according to Embodiment 5 of the present invention, where (a) is a cross-sectional view showing the overall configuration, and (b) is a block diagram of signal processing. In the figure, reference numeral 21 denotes a temperature sensor for measuring the cooling water temperature in the cooling chamber 100. In addition, since the cooling water temperature in the cooling chamber 100 and the cooling water temperature discharged from the cooling chamber 100 are considered to be substantially the same, in this embodiment, since the apparatus configuration is simple, the cooling water temperature is discharged from the cooling chamber 100. The temperature of the cooling water is measured.
Although the cooling water temperature is set to 15 ° C., for example, when the input power is increased to generate high-concentration ozone, the cooling water temperature rises, the temperature of the ground electrode 2 rises, and the ozone generation efficiency decreases. .
Therefore, in this embodiment, a temperature sensor 21 is provided in addition to the configuration shown in FIG. 4, and the input signals of the gas pressure sensor 15 and the water pressure sensor 16 are taken into the comparator 18 as shown in FIG. The pump pressure control device 17 controls the pump 13 so that the pressure difference is eliminated, and the temperature is adjusted by changing the flow rate of the cooling water by opening and closing the valve 19 so that the difference between the output of the temperature sensor 21 and the set temperature is eliminated. .
[0024]
In this way, since the water pressure and flow velocity of the cooling water are changed while monitoring the gas pressure and the temperature of the cooling water in the cooling chamber 100, there is almost no change in the discharge gap length due to the distortion of the electrode 2, and the temperature change of the electrode 2 Can be suppressed, and the decrease in ozone generation efficiency can be prevented.
[0025]
Embodiment 6 FIG.
FIG. 8 is a cross-sectional view showing a configuration of an ozone generator according to Embodiment 6 of the present invention. In the figure, 22 is a heat exchanger, and the cooling water is controlled to a predetermined temperature.
In the present embodiment, the cooling water circulation path composed of the cooling water supply pump 13, the cooling chamber 100, and the heat exchanger 22 is configured as a non-expanded and non-compressed closed system, and the cooling water circulation path includes gas only with cooling water. There is no such thing.
[0026]
In such a configuration, oxygen, air, or a mixed gas of oxygen and nitrogen, which is a raw material gas, is supplied from the gas supply port 7 into the pressure vessel 10. When this supply gas becomes high pressure, the grounded metal electrode 2 receives a force, but the grounded metal due to the incompressibility of water because the cooling water circulation path is constituted by a closed system and the cooling water is filled. The gap length can be accurately maintained without causing the electrode 2 to be distorted, and ozone can be generated efficiently.
[0027]
Embodiment 7 FIG.
9A and 9B show an electrode and a cooling chamber according to Embodiment 7 of the present invention, in which FIG. 9A is a plan view and FIG. 9B is a sectional view taken along line AA in FIG. In the present embodiment, the cooling water is sealed in the cooling chamber 100. In the figure, reference numeral 23 denotes a pipe through which a heat exchange refrigerant passes, and is arranged at the peripheral edge of the cooling chamber 100 to keep the cooling water at 15 ° C., for example. For example, water or ethylene glycol is used as the refrigerant for heat exchange.
[0028]
When the supply gas reaches a high pressure, the grounded metal electrode 2 receives a force, but since the cooling water is sealed in the cooling chamber 100 on the back of the ground electrode 2, it is grounded due to the incompressibility of water. The gap length can be accurately maintained without causing the metal electrode 2 to be distorted, and ozone can be generated efficiently.
[0029]
Embodiment 8 FIG.
FIG. 10 is a perspective view showing a partially broken electrode and cooling chamber according to Embodiment 8 of the present invention. In the figure, reference numeral 24 denotes a reinforcing member 24 of the ground electrode 2 disposed in the cooling chamber 100 on the back surface of the grounded metal electrode 2, and the surface facing the ground electrode 2 and the ground electrode 2 of the cooling chamber 100 is welded, for example. It is joined.
Even if the raw material gas pressure is increased by the reinforcing member 24, the gap length is accurately maintained without distortion of the ground electrode 2, and ozone can be generated efficiently.
[0030]
In addition, as shown in a plan view and a cross-sectional view taken along the line AA in FIGS. 11A and 11B, the reinforcing member 24 is disposed concentrically with the ground electrode 2 so that the ground electrode 2 is well balanced. It can be reinforced and processed easily and inexpensively.
[0031]
Embodiment 9 FIG.
FIG. 12 is a plan view showing an electrode provided with a cooling chamber, which is a main part of an ozone generator according to Embodiment 9 of the present invention. As shown in the figure, the reinforcing member 24 is provided in a spiral shape and the cooling water supply port 11 and the cooling water discharge port 12 are arranged at both ends thereof, so that the ground electrode 2 is not distorted even if the raw material gas pressure increases. In addition to maintaining the gap length with high accuracy, the flow path of the cooling water is configured, so that heat exchange is performed efficiently, and as a result, ozone generation efficiency is improved.
[0032]
Embodiment 10 FIG.
Next, the arrangement interval of the reinforcing members 24 will be described with reference to FIGS. When the source gas pressure is increased, the grounded metal electrode 2 is distorted toward the cooling chamber 100 as shown in FIG. If the maximum strain amount at this time is δ (cm), the strain amount δ can be expressed by the following equation by the radius a (cm) of the water channel and the thickness t (cm) of the ground electrode 2, for example, (Formulated for Stress and Strain by Raymond J. Roark and WC Young, 5th edition, 1986, McGraw-Hill, International Editions, page 339).
δ = K ₁ × qa ⁴ / D
D = Et ³ / {12 (1-ν ² )}
Here, q is the load (kg / cm ² ) of the ground electrode 2, E is the Young's modulus (kg / cm ² ) of the ground electrode 2, ν is the Poisson's ratio of the ground electrode 2, and b is the inner circumference of the ground electrode 2. Radius (cm). K ₁ is a constant determined by b / a. When b / a = 0.1, K ₁ = 0.006, when b / a = 0.3, K ₁ = 0.0029, b / a = 0. When it is 5, K ₁ = 0.0008.
[0033]
As apparent from the above equation, the strain amount δ can be reduced by increasing the thickness t of the ground electrode 2, but since the ground electrode 2 is usually made of stainless steel, the thermal conductivity is low and the thickness t is reduced. If it is designed to be thick, the temperature of the ground electrode 2 will rise, and the ozone generation efficiency will decrease. Therefore, because it can not increase the thickness t of the ground electrode 2, it is necessary to reinforce member 24 as shown in FIG. 13 (a).
[0034]
The reinforcing member 24 is provided on the concentric circumference of the ground electrode 2 at the positions of the radii c ₁ , c ₂ ,..., C _n (cm), and the distortion amounts are δ ₁ , δ _{2 ,.} When _{1, δ 1, δ 2,} ···, δ n-1 can be expressed as follows.
δ ₁ = K ₁₁ × qa ⁴ / D
δ ₂ = K ₁₂ × q (c ₁ ) ⁴ / D
・ ・ ・ ・ ・ ・
δ _n-1 = K _1n-1 × q (c _n ) ⁴ / D
It becomes.
[0035]
It is necessary to provide n reinforcing plates 24 so that all of δ1, δ2,... Δn are negligibly smaller than the gap length.
For example, the outer diameter a is 10 cm, the inner diameter b is 1.5 cm, the thickness t of the ground electrode 2 is 0.5 cm, the material of the ground electrode 2 is sus304, the Poisson's ratio ν is 0.3, and the Young's modulus E is 2 × 10 ^6. When the magnitude of the force applied to the ground electrode 2 (difference between supply gas pressure and water pressure) is 4 kgf / cm ² , δ = 0.78 cm.
In this case, by inserting two reinforcing members 24 at equal intervals (c1 = 20/3 cm, c2 = 10/3 cm), δ1 = 3.8 × 10 ⁻⁴ cm and δ2 = 2.7 × 10 ⁻⁴ cm. Δ3 = 2.9 × 10 ⁻⁵ cm, which is a sufficiently small strain amount with respect to a gap length of several tens to several hundreds μm.
[0036]
In each of the above embodiments, the cooling chamber 100 is provided on the metal electrode 2 on the ground side. However, the cooling chamber 100 may be provided on the high voltage electrode 3 or on both the electrodes 2 and 3.
[0037]
In each of the above-described embodiments, the case where the coolant supplied to the cooling chamber 100 is water has been described. However, the present invention is not limited to this, and for example, oil, ethylene glycol, or the like can be used.
[0038]
【The invention's effect】
According to the first aspect of the present invention, the two electrodes are disposed opposite to each other with the dielectric interposed therebetween, and discharge is caused by applying a high voltage therebetween, and provided on the back surface of at least one of the electrodes. A cooling chamber, a refrigerant supply mechanism for supplying a refrigerant to the cooling chamber, a gas supply mechanism for supplying a gas containing oxygen between the electrodes, and the one electrode provided inside the cooling chamber. Since the reinforcing member that supports the region opposite to the back surface from the back surface is provided, the gap length can be accurately maintained even under high gas pressure, and high-concentration ozone can be generated with high efficiency.
[0039]
According to the second invention, in the first invention, since the flow path of the refrigerant is formed by the reinforcing member, in addition to the effect of the first invention, heat exchange between the refrigerant and the electrode is performed by the refrigerant flow path. Since the efficiency is improved, the ozone generation efficiency can be further increased.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an ozone generator according to Embodiment 1 of the present invention.
FIG. 2 is a graph showing an example of ozone generation characteristics of the ozone generator according to Embodiment 1.
FIG. 3 is a graph showing an example of ozone generation characteristics of the ozone generator according to Embodiment 1.
4A and 4B show an ozone generator according to Embodiment 2 of the present invention, in which FIG. 4A is a cross-sectional view showing the overall configuration, and FIG. 4B is a block diagram of signal processing.
5A and 5B show an ozone generator according to Embodiment 3 of the present invention, in which FIG. 5A is a cross-sectional view showing the overall configuration, and FIG. 5B is a block diagram of signal processing.
FIG. 6 is a cross-sectional view showing a configuration of an ozone generator according to Embodiment 4 of the present invention.
FIGS. 7A and 7B show an ozone generator according to Embodiment 5 of the present invention, in which FIG. 7A is a cross-sectional view showing the overall configuration, and FIG. 7B is a block diagram of signal processing.
FIG. 8 is a cross-sectional view showing a configuration of an ozone generator according to Embodiment 6 of the present invention.
FIGS. 9A and 9B show a configuration of a main part of an ozone generator according to Embodiment 7 of the present invention, where FIG. 9A is a plan view and FIG. 9B is a cross-sectional view taken along line AA in FIG.
FIG. 10 is a perspective view showing a configuration of a main part of an ozone generator according to Embodiment 8 of the present invention.
11 shows a configuration of a main part of an ozone generator according to an eighth embodiment of the present invention, where (a) is a plan view and (b) is a cross-sectional view taken along line AA of (a). FIG.
FIG. 12 is a plan view showing a configuration of a main part of an ozone generator according to Embodiment 9 of the present invention.
FIG. 13 is a diagram for explaining an ozone generator according to a tenth embodiment of the present invention.
FIG. 14 shows a main part of a conventional ozone generator, in which (a) is a cross-sectional view and (b) is a left half front view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power supply, 2 Grounded metal electrode, 3 High voltage electrode, 4 Dielectric, 5 Discharge space, 6 Spacer, 7 Arrow which shows gas supply direction, 8 Arrow which shows gas discharge direction, 9 Gas discharge pipe, 10 Pressure vessel, DESCRIPTION OF SYMBOLS 11 Cooling water supply port, 12 Cooling water discharge port, 13 Pump, 14 Cooling water reservoir, 15 Pressure sensor, 16 Pressure sensor, 17 Pump discharge pressure control device, 18 Comparator, 19 Valve, 20 Piezoelectric element, 21 Temperature sensor , 22 heat exchanger, 23 heat exchange pipe, 24 reinforcing member, 100 cooling chamber.

Claims (3)

Two electrodes disposed opposite to each other with a dielectric applied thereto, and causing a discharge by applying a high voltage therebetween, a cooling chamber provided on the back surface of at least one of the electrodes, and the cooling chamber A refrigerant supply mechanism for supplying refrigerant to the gas, a gas supply mechanism for supplying a gas containing oxygen between the electrodes, and a region provided inside the cooling chamber where the one electrode faces the other electrode is supported from the back side. An ozone generator characterized by comprising a reinforcing member to be used. The ozone generator according to claim 1, wherein a flow path for the refrigerant is formed by the reinforcing member. 3. The ozone generator according to claim 1, wherein one electrode is made of stainless steel, and the cooling chamber is provided so that the refrigerant directly contacts the back surface of the one electrode.

Images