JP2013184861A - Ozone generating apparatus and ozone generating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ozone generating apparatus and an ozone generating method capable of efficiently generating ozone in a higher saturation ozone concentration.SOLUTION: An ozone generating means of an ozone generating apparatus applies a given voltage between a high potential side electrode and a low electric potential side electrode to discharge electricity, and generates an ozone gas from a material gas, that contains an oxygen gas, supplied between the electrodes. A cooling means concurrently cools at least either of the high potential side electrode and the low electric potential side electrode to a temperature not more than 0°C and higher than the boiling point of the ozone gas.

Description

  Embodiments described herein relate generally to an ozone generator and an ozone generation method.

  In a general ozone generator, a pair of one electrode provided inside a cylindrical discharge tube and the other electrode provided around the one electrode outside the discharge tube are used as a discharge electrode. A small discharge gap (space) is formed by inserting a spacer between them. One electrode is usually disposed in close contact with the inner surface of the discharge tube as a conductive film, and constitutes the discharge tube, the conductive film, and the dielectric electrode. A dielectric barrier discharge is generated in the discharge gap by flowing an ozone source gas containing oxygen gas into the discharge gap between the discharge tube and the stainless steel tube, which is the metal electrode as the other electrode, and applying an AC high voltage between the two electrodes. Occur. Ozonized gas is generated by this dielectric barrier discharge. The dielectric barrier discharge is sometimes simply referred to as barrier discharge or silent discharge.

JP-A-10-182109

However, in the conventional ozone generator, the heat generated by the dielectric barrier discharge is cooled by, for example, cooling water supplied into the metal electrode. Thereby, the gas temperature rise of a discharge gap can be suppressed and the thermal decomposition of ozone can be suppressed. In this case, of course, the temperature of the discharge part can be cooled only to the temperature of the cooling water. Since the cooling water is usually around 15 to 30 ° C., thermal decomposition of ozone occurs. Therefore, the maximum value of the saturated ozone concentration is 300 to 400 g / Nm ³ .
Here, the saturated ozone concentration is the concentration (value) of ozone in which the generation and decomposition of ozone were balanced, and the concentration of the generated ozone could not be further increased.

  This invention is made | formed in view of the above, Comprising: It aims at providing the ozone generator and ozone generating method which can produce | generate ozone efficiently with higher saturated ozone concentration.

The ozone generation means of the ozone generator according to the embodiment causes a discharge by applying a predetermined voltage between the high potential side electrode and the low potential side electrode, and from the source gas containing oxygen gas supplied between the electrodes. Generates ozone gas.
In parallel with this, the cooling means cools at least one of the high potential side electrode and the low power side electrode to a temperature of 0 ° C. or lower and higher than the boiling point of ozone gas.

FIG. 1 is a schematic configuration diagram of an ozone generator according to the first embodiment. FIG. 2 is a diagram showing the relationship between the ozone concentration and the ozone generation efficiency in the ozone generator of the first embodiment for each electrode temperature. FIG. 3 is a schematic configuration diagram of an ozone generator according to the second embodiment. FIG. 4 is a diagram showing the relationship between the ozone concentration and the ozone generation efficiency in the ozone generator of the second embodiment for each electrode temperature. FIG. 5 is a schematic configuration diagram of an ozone generator according to the third embodiment.

Next, embodiments will be described with reference to the drawings.
[1] First Embodiment FIG. 1 is a schematic configuration diagram of an ozone generator according to a first embodiment.
The ozone generator 10 of the first embodiment is configured as a dielectric barrier discharge type ozone generator.

  The ozone generator 10 has a first electrode 11 (power supply side electrode) 11 made of stainless steel, a second electrode 12 made of stainless steel (grounding side electrode) 12, and a second electrode 12 facing each other. And a disposed dielectric barrier (dielectric) 13. Here, the dielectric barrier 13 is preferably made of quartz glass having a small thermal expansion coefficient. A conductive film 13A is formed on the surface of the dielectric barrier 13 that faces the second electrode. Further, the discharge gap length d between the first electrode 11 and the second electrode 12 is such that when the gas pressure (absolute pressure) of the supplied source gas is p, the product p · d is a desired value ( For example, it is set to 20 kPa · cm.

The ozone generator 10 includes a refrigerator 14, and the second electrode 12 is a heat exchanger for the refrigerator 14, or the second electrode 12 is thermally connected to a heat exchanger (not shown) of the refrigerator 14. Is bound to.
Further, a high voltage AC power supply 15 is connected to the first electrode 11, and the second electrode 12 is grounded.

In the above configuration, when an AC high voltage is applied between the first electrode 11 and the second electrode 12 by the high voltage AC power supply 15, a dielectric barrier discharge is generated between the dielectric barrier 13 and the second electrode 12. 16 is generated.
At this time, oxygen gas (O ₂ gas) as a source gas is not shown between the first electrode 11 and the second electrode 12, more specifically, between the dielectric barrier 13 and the second electrode 12. The refrigerator 14 supplies the second electrode 12 with a temperature of 0 ° C. or lower and a temperature equal to or higher than the boiling point of ozone (O ₃ ) (−111.9 ° C. under 1 atm). It has cooled down.

As a result, when the equilibrium state is reached, the temperature of the oxygen gas (O ₂ gas) supplied between the dielectric barrier 13 and the second electrode 12 becomes the boiling point of ozone to 0 ° C., which is a relatively low temperature gas. It has become.
Then, the dielectric barrier discharge 16 generated between the second electrode 12 and the dielectric barrier 13 generates ozone gas (O ₃ gas) from oxygen gas (O ₂ gas) at a relatively low temperature, and is discharged outside the electrode. The
The discharged ozone gas (O ₃ gas) is recovered, and ozone water can be formed by bubbling in water, for example.

FIG. 2 is a diagram showing the relationship between the ozone concentration and the ozone generation efficiency in the ozone generator of the first embodiment for each electrode temperature.
In FIG. 2, the symbol L0 indicates that the temperature of the second electrode 12 is 0 ° C., the symbol L-50 indicates that the temperature of the second electrode 12 is −50 ° C., and the symbol L-100 indicates that the temperature of the second electrode 12 is This is the case when the temperature is −100 ° C.

In FIG. 2, the ozone generation efficiency [g / kWh] was calculated by measuring the ozone concentration [g / Nm ³ ], power [kW], and gas flow rate [Nm ³ / h] and obtaining the ratio. .
The ozone concentration was obtained by measuring the ozone concentration discharged from the discharge part using an ozone monitor manufactured by Sugawara Jitsugyo.

As shown in FIG. 2, the lower the temperature of the second electrode 12, the higher the generated ozone concentration. The maximum ozone concentration at each temperature is the saturated ozone concentration.
Specifically, the saturated ozone concentration, 300 g ^/ Nm 3 temperature at 0 ℃ of the second electrode 12, 550 g ^/ Nm 3 at -50 ° C., and has a 900 g / Nm ³ at -100 ° C..
The ozone generation efficiency is higher as the temperature of the second electrode 12 is lower, and becomes 225 g / kWh at 0 ° C., 250 g / kWh at −50 ° C., and 260 g / kWh at −100 ° C. That is, it can be seen that the lower the temperature, the higher the ozone generation efficiency and the ozone concentration.

  In the above description, the second electrode 12 is described as the heat exchanger of the refrigerator 14 or the second electrode 12 is thermally coupled to the heat exchanger of the refrigerator 14. At least one of the first electrode 11 and the second electrode 12 is a heat exchanger of the refrigerator 14, or at least one of the first electrode 11 and the second electrode 12 is thermally connected to the heat exchanger of the refrigerator. If it is made to couple | bond with, it is possible to acquire the same effect.

[2] Second Embodiment FIG. 3 is a schematic configuration diagram of an ozone generator according to a second embodiment.
Although the ozone generator 10 of the first embodiment is configured as a dielectric barrier discharge type ozone generator, the ozone generator 20 of the second embodiment is configured as a pulse discharge type ozone generator. Is.
In FIG. 3, the same parts as those in FIG.

The second embodiment is different from the first embodiment in that a high voltage pulse power supply 21 is provided instead of the high voltage AC power supply 15.
Thereby, compared with 1st Embodiment, the ion loss during discharge can be reduced and ozone can be generated more efficiently.

  In this case, the conduction loss of ions is reduced by making the application time of the pulse voltage shorter than the time required for the movement of ions between the first electrode 11 and the second electrode 12 (about 10 microseconds). The generation efficiency can be as high as 400 g / kWh.

By the way, if the power source is simply a pulse power source, the ozone generation efficiency decreases as the ozone concentration increases. For example, as shown in FIG. 14 (b) of Kuramoto et al.'S paper “Ozone generation using ns pulsed discharge”, IEEJ Discharge Study Group document ED-8-94 (2008) P51-56, oxygen source ozone generation from is higher efficiency of several g / Nm ³ in 500 g / kWh ozone concentration is obtained, the 30 g / Nm ³ efficiency would dropped to about a half.

  On the other hand, according to this 2nd Embodiment, the fall of efficiency can be suppressed by making the 2nd electrode 12 into low temperature using the refrigerator 14. FIG.

FIG. 4 is a diagram showing the relationship between the ozone concentration and the ozone generation efficiency in the ozone generator of the second embodiment for each electrode temperature.
In FIG. 4, symbol L0A indicates that the temperature of the second electrode 12 is 0 ° C., symbol L-50A indicates that the temperature of the second electrode 12 is −50 ° C., symbol L-100A indicates that the second electrode 12 This is the case when the temperature is −100 ° C.

As shown in FIG. 4, the lower the electrode temperature is, the higher the generated ozone concentration is, as in the case of using the high voltage AC power supply 15 of FIG.
The maximum ozone generation efficiency at each temperature is 350 g / kWh at 0 ° C., 375 g / kWh at −50 ° C., and 400 g / kWh at −100 ° C. It can be seen that the lower the temperature, the higher the ozone generation efficiency and the ozone concentration. Also, small decrease of the ozone generating efficiency due to an increase in the ozone concentration, the ozone concentration is 0 ℃ at 240 g ^/ Nm 3 of ozone generating efficiency drops to half, 500 g ^/ Nm 3 at -50 ℃, 860g / Nm ³ at -100 ° C. become.

  According to the second embodiment, it can be seen that also in the pulse discharge type ozone generator 20, a decrease in efficiency can be suppressed by using the refrigerator 14 to lower the temperature, and high efficiency and high concentration can be obtained.

  In the above description, the second electrode 12 is described as the heat exchanger of the refrigerator 14 or the second electrode 12 is thermally coupled to the heat exchanger of the refrigerator 14. At least one of the first electrode 11 and the second electrode 12 is a heat exchanger of the refrigerator 14, or at least one of the first electrode 11 and the second electrode 12 is thermally connected to the heat exchanger of the refrigerator. If it is made to couple | bond with, it is possible to acquire the same effect.

[3] Third Embodiment FIG. 5 is a schematic configuration diagram of an ozone generator according to a third embodiment.
The ozone generator 20 of the third embodiment is configured as a pulse / wire discharge type ozone generator, and supplies oxygen gas, which is vaporized liquid oxygen and has the above temperature, as the source gas between the electrodes. The electrode is cooled to a temperature not higher than 0 ° C. and not lower than the boiling point of ozone.

  The ozone generator 30 includes a first electrode 31 that is a cylindrical electrode made of stainless steel, and a second electrode configured as a wire electrode that is inserted into the first electrode 31 in parallel with the longitudinal direction of the first electrode 31. An electrode 32, a high-voltage pulse power source 33 for applying a high-voltage pulse connected to the second electrode 32, and liquid oxygen (LOX) 34 are accommodated and gradually vaporized (evaporated) to form oxygen gas. As an evaporator 35 and a pipe (not shown) for supplying oxygen gas from the evaporator 35 to the inside of the first electrode 31.

  In this case, a cylindrical heat transfer tube that is slightly larger than the first electrode 31 and can be disposed in a state where the first electrode 31 is accommodated, and is drawn into the evaporator 35 from the heat transfer tube to be vaporized (evaporated). It is also possible to provide a heat transfer member provided with a heating wire that transmits the required heat.

In the above configuration, when a pulse high voltage is applied between the high voltage pulse power source 33 and the second electrode 32, a pulse discharge is generated inside the first electrode 31.
In the evaporator 35, for example, liquid oxygen (LOX) 34 of −182.96 ° C. is accommodated. Liquid oxygen (LOX) 34 can be evaporated by an evaporator 35 to obtain oxygen gas. Vaporized oxygen becomes low-temperature oxygen gas of −111.9 ° C. to 0 ° C. (−100 ° C. in the example of FIG. 5), and is supplied into the first electrode 31 through a pipe (not shown). In this case, when it is desired to control the temperature of the supplied oxygen gas, a heater, a temperature sensor, and the like may be provided in the middle of a pipe (not shown) to heat it to a desired temperature.

Accordingly, pulse discharge occurs between the first electrode 31 and the second electrode 32, and the low-temperature oxygen gas generates ozone and is discharged outside the first electrode 31.
Here, when the heat transfer member is provided, the heat energy generated in the first electrode 31 is supplied from the heat transfer tube to the evaporator 35, and this heat energy is used to evaporate the liquid oxygen 34. Can be used.

The generated ozone gas can form ozone water by, for example, bubbling with water.
The ozone or ozone water formed using the ozone generator according to the embodiment can be applied to, for example, water treatment technology and used for deodorization, decolorization, sterilization, and the like of water to be treated.

  In the above description, the first electrode 31 that is a cylindrical electrode is made of stainless steel. However, the inner surface of the cylindrical glass that is a dielectric is plated with aluminum, nickel, or the like, or aluminum, nickel, stainless steel, or the like is used. It is also possible to form the conductor into a thin film by sputtering. Thereby, the 1st electrode excellent in corrosion resistance can be comprised, and it becomes possible to produce | generate ozone with a stable density | concentration with high efficiency.

[4] Modification of Embodiment In the first embodiment and the second embodiment described above, a configuration in which oxygen gas, which is a raw material gas, is simply supplied from the outside of the ozone generator has been adopted. Similarly, it is also possible to provide an evaporator and supply oxygen gas obtained by vaporizing liquid oxygen as a raw material gas.
It is also possible to supply the oxygen gas introduced from the outside cooled with liquid oxygen according to the third embodiment.

[5] Effects of Embodiments According to these embodiments, the temperature of oxygen vaporized in an ozone generator that generates ozone by discharge is reduced to a low temperature (0 ° C.) using oxygen gas vaporized by evaporating liquid oxygen as a raw material. By setting the temperature to the following temperature, which is equal to or higher than the boiling point of ozone: for example, a temperature of -111.9 ° C. to 0 ° C., the thermal decomposition of ozone can be suppressed, and high-concentration ozone can be generated with high efficiency.

  The generated ozone gas or ozone water obtained by bubbling with this ozone gas water is applied to, for example, water treatment technology, and is used for deodorization, decolorization, sterilization, etc. of water to be treated, thereby making it more efficient. Therefore, these processes can be performed.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 Ozone generator 11 First electrode (ozone generating means)
12 Second electrode (Ozone generating means)
13 Dielectric barrier (dielectric)
13A conductive film 14 refrigerator (cooling means)
15 High-voltage AC power supply (ozone generating means)
16 Dielectric Barrier Discharge 20 Ozone Generator 21 High Voltage Pulse Power Supply 30 Ozone Generator 31 First Electrode 32 Second Electrode (Wire Electrode)
33 High-voltage pulse power supply 34 Liquid oxygen (cooling means)
35 Evaporator (cooling means)

Claims (9)

An ozone generating means for applying a predetermined voltage between the first electrode and the second electrode to cause discharge, and generating ozone gas from a source gas containing oxygen gas supplied between the electrodes;
A cooling means for cooling at least one of the first electrode and the low power side electrode to a temperature of 0 ° C. or less and a temperature of a boiling point or more of the ozone gas;
Ozone generator equipped with. The cooling means supplies oxygen gas having the temperature by vaporizing liquid oxygen as the source gas between the electrodes.
The ozone generator according to claim 1. A vaporization unit for vaporizing the liquid oxygen;
Supplying heat generated by the discharge to the vaporizing unit;
The ozone generator of Claim 1 or Claim 2. Have a refrigerator,
At least one of the first electrode and the second electrode is used as a heat exchanger for the refrigerator, or at least one of the first electrode and the second electrode is used as a heat exchanger for the refrigerator. Thermally coupled,
The ozone generator according to claim 1. The ozone generation means includes a pulse power supply connected to either the first electrode or the second electrode, and includes a pulse discharge type discharge means for applying a pulse voltage.
The ozone generator in any one of Claim 1 thru | or 4. Either the first electrode or the second electrode is formed as a wire electrode, the other is formed as a cylindrical electrode,
The wire electrode comprises a pulse wire discharge type discharge means inserted into the cylindrical electrode,
The ozone generator in any one of Claim 1 thru | or 4. The application time of the pulse voltage is set shorter than the ion movement time between the first electrode and the second electrode.
The ozone generator of Claim 5 or Claim 6. The ozone generating means includes a dielectric provided between the first electrode and the second electrode, and an AC power source connected to either the first electrode or the second electrode. Provided with a dielectric barrier discharge type discharge means,
The ozone generator in any one of Claim 1 thru | or 4. An ozone generation method executed in an ozone generator provided with a first electrode and a second electrode,
An ozone generation process in which discharge is performed by applying a predetermined voltage between the first electrode and the second electrode, and ozone gas is generated from a source gas containing oxygen gas supplied between the electrodes;
A cooling process in which at least one of the first electrode and the low power side electrode is cooled to a temperature of 0 ° C. or lower and higher than the boiling point of the ozone gas;
A method for generating ozone.

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