JP2003238117A - Apparatus for generating ozone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for generating ozone by electrical discharge which can eliminate such disadvantages that a corrosive material such as nitric acid is formed by a reaction of a nitrogen oxide stable at room temperature and remains in the apparatus with moisture that is contained in the atmosphere when the apparatus is opened for inspection, the apparatus is damaged and the service life of is shortened. <P>SOLUTION: In the apparatus for generating ozone a heating device for heating the interior of the vessel containing electrodes of the apparatus for generating ozone when the operation of the apparatus is suspended above the boiling point of the nitrogen oxides is provided, and in that the nitrogen oxides in the vessel is discharged outside of the vessel by supplying to and evacuating from the vessel an inert gas. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone generator for generating ozone from oxygen by discharging.

[0002]

2. Description of the Related Art Oxidation of oxygen (O ₂ →
O _3), an ozone generator for generating ozone from oxygen are known. When ozone is generated, there is a quantitative difference, but oxygen as a raw material gas contains a small amount of nitrogen, except when high-purity oxygen is used as a raw material gas for generating ozone. When a discharge is performed using a raw material gas containing nitrogen, some kinds of nitrogen oxides (NO _x ) are always produced as by-products. Of the generated nitrogen oxides, those that are gas or unstable at room temperature are discharged out of the device along with ozone, but nitrogen oxides mainly composed of dinitrogen pentoxide, which is relatively stable at room temperature, remain inside the device. ,accumulate.

These remaining nitrogen oxides react violently with moisture when moisture is mixed from the outside when the device is opened for inspection of the ozone generator or when it is not used for a long time, and nitric acid, nitrous acid, etc. It produces a corrosive substance. These corrosive substances may corrode the electrodes and main body parts in the ozone generator, and may seriously damage the device.

[0004]

At present, no means for efficiently removing these remaining corrosive substances has been established, which corrodes the electrodes and main body parts and greatly extends the life of the ozone generator itself. Has become a factor to reduce. Therefore, there is a demand for means for efficiently discharging nitrogen oxides to the outside of the ozone generator under the condition that these highly corrosive substances are not generated.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide an ozone generator in which the life of a product is extended by efficiently removing nitrogen oxides generated and accumulated due to discharge.

[0006]

In order to achieve the above object, the invention according to claim 1 is an ozone generator which oxidizes oxygen by discharge to generate ozone. A heating device for heating the inside of the container accommodating the electrodes to a boiling point or a sublimation point of nitrogen oxides or above, and an inert gas supply device for supplying and exhausting an inert gas into the container are provided. . According to the present invention, nitrogen oxides are sublimated and decomposed into a gas state, which is discharged from the container to the outside by the inert gas and removed.

According to the second aspect of the invention, in an ozone generator that oxidizes oxygen by discharge to generate ozone, the inside of the container accommodating the electrodes of the ozone generator when the operation of the ozone generator is stopped is nitrogen-oxidized. A heating device for heating to above the boiling point or sublimation point of an object, an inert gas supply device for supplying and exhausting an inert gas into the container, and the exhaust gas being absorbed in pure water or an absorbing liquid, or the pure water or A gas discharge detection device for detecting the removal state of nitrogen oxides inside the container by measuring the change in conductivity of the absorbing liquid or the change in pH is provided. According to the present invention, the conductivity or pH of pure water or the absorbing liquid is monitored, and when saturated, it is determined that the nitrogen oxides have been completely discharged out of the ozone generator.

According to the invention of claim 3, in the ozone generator of claim 1 or 2, a heating device is provided around the ozone generator main body. According to the present invention, nitrogen oxides are sublimated and decomposed into a gas state, which is discharged from the container to the outside by the inert gas and removed.

According to the invention described in claim 4, in the ozone generator according to claim 1 or 2, a heating device is provided in a part of the supply pipe for blowing oxygen into the ozone generator. According to this invention, nitrogen oxides are sublimated,
It is decomposed into a gas, and is discharged to the outside from the container by an inert gas and removed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of an ozone generator of the present invention. In FIG. 1, 1
Is an ozone generator having coaxial discharge electrodes 3a and 3b facing the inside of the container 2. Reference numeral 4 is a cooler for cooling the electrodes 3a, 3b when the ozone generator is in operation.
It is connected to the electrodes 3a and 3b via a cooling pipe 5 to form a cooling system. A pump 6 is provided in the middle of the cooling pipe, and circulates the refrigerant from the cooler 4 to the electrodes 3a and 3b. Reference numeral 7 is a bypass pipe connected to the cooling pipe 5 so as to bypass the cooler 4, and the cooling pipe 5 is provided by switching between valves 8a and 8b provided in the cooling pipe 5 and a valve 8c provided in the bypass pipe 7. The circulation path of the internal refrigerant is bypassed to the cooler 4. A heating device 9 is connected in parallel to the cooling pipe 5 between the ozone generator 1 and the pump 6, and includes valves 8d and 8e provided on the heater 9 side and a valve 8f provided on the cooling pipe 5. By switching, the flow of the refrigerant in the cooling pipe 5 can be switched to the heating device 9 side.

In the ozone generator of the present invention as described above, when the normal ozone generator is in operation, a discharge is generated between the electrodes 3a and 3b so that oxygen supplied from the raw material gas supply pipe (not shown) into the container 2 is generated. Is oxidized to generate ozone. The electrodes 3 a and 3 b whose temperature has risen due to the discharge are cooled by the refrigerant sent from the cooler 4 by the operation of the pump 6.

In such an ozone generator, when the device is opened for inspection or when it is not used for a long period of time, the open / closed state of the valves 8a and 8b, the valve 8c and the valves 8d and 8e and the valve 8f should be changed. The cooling system is switched to switch the cooling system so that the refrigerant in the cooling pipe 5 bypasses the cooler 4 and passes through the heating device 9. The heating device 9 heats the refrigerant,
It is sent into the container 2 by the pump 6 and the inside of the container is heated to 33 ° C.
Heat to the above temperature.

Generally, dinitrogen pentoxide, which is a relatively stable nitrogen oxide, has a low sublimation point of 32.4 ° C., has a hygroscopic property, and has a property of being well dissolved in water. Therefore, by heating the inside of the container 2 to 33 ° C. or higher, the dinitrogen pentoxide in the container 2 is sublimated and decomposed into a gaseous state. Container 2 in this state
By blowing an inert gas such as high-purity oxygen or high-purity argon from the outside into the container 2 from an inert gas supply device 11 provided outside the container 2, and exhausting the gas inside from the exhaust port 10 to the outside of the container 2, It is possible to remove nitrogen oxides that remain in the container 2 and cause deterioration of the electrodes and the like.

In the first embodiment, a bypass circuit is provided in the cooling system of the ozone generator, and a heating device is provided therein to send the heated refrigerant into the container 2 by switching the valve. Also, the same effect can be obtained by heating the inside of the container 2 inside the ozone generator to 47 ° C. or higher by attaching a heater such as a heater to the ozone generator body or by attaching a heater to the feed line of the raw material gas to be introduced. Can be achieved.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing a second embodiment of the ozone generator of the present invention. In FIG. 2, FIG.
The same parts as those of the above are denoted by the same reference numerals, and detailed description thereof will be omitted.
Reference numeral 12 is a gas discharge detection device provided so as to be connected to the exhaust port 10 in the first embodiment. A predetermined amount of pure water 14 for gas absorption is put in the detection container 13, and a conductivity meter is placed in the pure water 14. The conductivity meter 15 is provided so that the detection part of 1 is immersed. FIG. 3 shows a change in conductivity of pure water with time change of gas discharge of dinitrogen pentoxide, and as shown by a curve A, it rapidly rises in the initial stage of gas discharge from the discharge port 10,
A tendency to be saturated over time is observed. When this conductivity is saturated, it is judged that the nitrogen oxides inside the container 2 have been completely discharged to the outside of the ozone generator.

Further, instead of the conductivity meter shown in FIG.
The same effect can be obtained when a meter is installed. In this case, as shown by the curve B in FIG. 4, the pH decreases with the elapse of the gas discharge time, and when the pH decreases to a certain value and there is no change, the nitrogen oxides inside the container 2 are completely ozone. Judged as having been discharged outside the generator. This makes it possible to accurately detect the discharge state of nitrogen oxides. It is also possible to use another absorbing liquid instead of pure one.

Next, a third embodiment of the present invention will be described. In the ozone generator, nitric acid resistance is improved by using stainless steel, aluminum or aluminum alloy as a material forming the structure inside the container 2. Table 1 compares the corrosion resistance of metallic materials in the environment inside the ozone generator with copper as 1. The use of stainless steel, aluminum or aluminum alloy prevents corrosion of the main body and damages are less than several tenths. Can be suppressed to.

[0018]

[Table 1]

As described above, by constructing the internal structure of the ozone generator with a material that is resistant to corrosive substances, the life of the ozone generator can be extended.

[0020]

As described above, according to the present invention,
In an ozone generator that oxidizes oxygen by discharge to generate ozone, a heating device that heats the inside of a container accommodating the electrodes of the ozone generator when the ozone generator is stopped to a temperature above the boiling point or sublimation point of nitrogen oxides. Since an inert gas supply device for supplying and exhausting an inert gas is provided in the container, it is possible to efficiently remove the nitrogen oxides generated and remaining accumulated due to the discharge, thereby prolonging the life of the product. It is possible to obtain an excellent ozone generator.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic system diagram showing a second embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a change in conductivity obtained when detecting removal of nitrogen oxides.

FIG. 4: pH obtained when detecting removal of nitrogen oxides
FIG.

[Explanation of symbols]

1 ... Ozone generator, 2 ... Container, 3a, 3b ... Electrode, 4
... Cooler, 5 ... Cooling pipe, 6 ... Pump, 7 ... Bypass pipe,
9 ... Heating device, 10 ... Exhaust port, 11 ... Inert gas supply device, 12 ... Gas discharge detection device, 13 ... Detection container, 14 ...
Pure water, 15 ... Conductivity meter.

Claims (4)

[Claims] 1. An ozone generator that oxidizes oxygen by discharge to generate ozone, in a container accommodating electrodes of the ozone generator when the operation of the ozone generator is stopped,
An ozone generator comprising: a heating device that heats to a temperature not lower than the sublimation point of nitrogen oxides; and an inert gas supply device that supplies and exhausts an inert gas into the container. 2. An ozone generator that oxidizes oxygen by discharge to generate ozone, in a container accommodating electrodes of the ozone generator when the ozone generator is not operating,
A heating device that heats to a temperature not lower than the sublimation point of nitrogen oxides, an inert gas supply device that supplies and exhausts an inert gas into the container, and the exhaust gas is absorbed in pure water or an absorbing liquid, and the pure water or An ozone generator, comprising: a gas discharge detection device that detects a removal state of nitrogen oxides inside the container by measuring a change in conductivity of the absorbing liquid or a change in pH. 3. The ozone generator according to claim 1, wherein a heating device is provided around the ozone generator main body. 4. The ozone generator according to claim 1 or 2, wherein a heating device is provided in a part of a supply pipe for blowing oxygen into the ozone generator.