JP2014118342A - Ozone generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently generate ozone by improving a power factor.SOLUTION: In an ozone generator, a predetermined high voltage is applied between a first electrode and a second electrode through a dielectric and an electric discharge gap of a predetermined length, thereby discharging electricity to a raw material gas flowing through the electric discharge gap to generate ozone. The thickness of the dielectric and the length of the electric discharge gap are set so that the electrostatic capacity Cd of the dielectric and the electrostatic capacity Ca of the electric discharge gap satisfy Cd>Ca.

Description

  Embodiments described herein relate generally to an ozone generator.

  In a general ozone generator, a discharge gap is provided between a high-voltage electrode in which a conductive film is disposed on a dielectric material such as glass and a ground-side metal electrode having a cooling function. By flowing an ozone raw material gas and applying an AC high voltage, a dielectric barrier discharge is generated in the discharge gap to generate an ozonized gas. The dielectric barrier discharge is sometimes called silent discharge.

Since ozone is weak to heat and decomposes with heat even if it is generated, heat generated by dielectric barrier discharge is suppressed by the cooling function on the ground side, ozone decomposition is suppressed, and ozone generation efficiency is reduced. It is preventing.
In recent years, the power density W / S has increased, and the cooling effect has been enhanced by shortening the discharge gap by increasing the concentration of generated ozone. The average temperature rise ΔT in the discharge space is
ΔT = (1 / (3 · k)) × (W / S) × d
It is represented by
Here, k is the thermal conductivity of the gas, W is the discharge power, S is the discharge area, and d is the discharge gap.

JP-A-10-182109

  However, in the conventional ozone generator, the power factor of the AC power supply (the ratio of the effective power to the apparent power) is not necessarily high, and the efficiency of ozone generation with respect to the input power amount is low.

  This invention is made | formed in view of the above, Comprising: It aims at the improvement of a power factor and it aims at providing the ozone generator which can produce | generate ozone efficiently.

In the ozone generator of the embodiment, a predetermined high voltage is applied between the first electrode and the second electrode through a dielectric and a discharge gap having a predetermined length to discharge the raw material gas flowing in the discharge gap, It is an ozone generator that generates ozone.
The dielectric capacitance Cd and the discharge gap capacitance Ca are:
Cd> Ca
The thickness of the dielectric and the discharge gap length are set so as to satisfy the above.

FIG. 1 is an explanatory diagram of a schematic configuration of the ozone generator according to the first embodiment. FIG. 2 is an explanatory diagram of an equivalent circuit of the discharge unit of the ozone generator before the silent discharge is generated. FIG. 3 is an explanatory diagram of an equivalent circuit of the discharge unit of the ozone generator when silent discharge occurs. FIG. 4 is an explanatory diagram of the impedance vector of the discharge part. FIG. 5 is a schematic configuration explanatory diagram of an ozone generator according to the second embodiment.

Next, embodiments will be described with reference to the drawings.
[1] First Embodiment FIG. 1 is an explanatory diagram of a schematic configuration 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 desirably a dielectric (for example, 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 first electrode 11.

  Here, the second electrode 12 and the dielectric barrier 13 are separated by the discharge gap length d by the spacer 14 to form a discharge gap G. Further, the discharge gap length d is a desired value (for example, discharge gap length d = 0.3 mm to 0.00 mm) when the gas pressure (absolute pressure) of the supplied raw material gas is p. When the source gas is air, it is set to 7 to 16 kPa · cm.

Further, a high voltage AC power supply 15 is connected to the first electrode 11 via an overcurrent interruption element (for example, a fuse) 16, and the second electrode 12 is grounded.
In the above configuration, the first electrode 11, the second electrode 12, the dielectric barrier 13, and the spacer 14 are accommodated in the airtight container 17.

  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. Will occur.

  At this time, air as a source gas is supplied between the first electrode 11 and the second electrode 12, more specifically, between the dielectric barrier 13 and the second electrode 12 by the gas inlet pipe 21. Yes. At this time, the second electrode 12 is cooled by the cooling water CW supplied from the cooling water inlet pipe 22 so that the generated ozone is not decomposed. And the cooling water CW after cooling is discharged | emitted out of the airtight container 17 through the cooling water exit piping 23. FIG.

Then, due to the dielectric barrier discharge generated between the second electrode 12 and the dielectric barrier 13, ozone gas (O ₃ gas) is generated from the air and discharged outside the electrode through the gas outlet pipe 24.
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.

FIG. 2 is an explanatory diagram of an equivalent circuit of the discharge unit of the ozone generator before the silent discharge is generated.
The equivalent circuit of the discharge part of the ozone generator until the silent discharge is formed is a series circuit of capacitors. The electrostatic capacitance Cg of the dielectric and the electrostatic capacitance Ca of the discharge gap are respectively expressed by the following equations.
Cg = εg · S / dg (1)
Ca = εa · S / da (2)
Here, εg is the dielectric constant of the dielectric barrier 13, S is the discharge area, dg is the thickness of the dielectric barrier 13, εa is the dielectric constant of the discharge gap G, and da is the gap length of the discharge gap G.

FIG. 3 is an explanatory diagram of an equivalent circuit of the discharge unit of the ozone generator when silent discharge occurs.
FIG. 4 is an explanatory diagram of the impedance vector of the discharge part.
The discharge part of the ozone generator 10 when silent discharge occurs is represented as a series circuit of resistors and capacitors (RC series circuit).
At this time, when the reactance is Xc, the resistance is R, and the impedance of the discharge unit is Z, the impedance vector of the series circuit of the resistor and the capacitor is as shown in FIG.

That is, since the power factor of the discharge part when viewed from the high voltage AC power supply 15 is represented by cos θ, tan θ may be reduced in order to increase the power factor of the discharge part in order to reduce the size of the power supply.
Here, since the resistance R is determined by the discharge gap length d, when the discharge gap length d is constant, the reactance Xc may be reduced in order to increase the power factor of the discharge part.

By the way, the reactance Xc is expressed as follows.
Xc = 1 / (ω · Cg)
Here, ω is an angular frequency.
Therefore, in order to reduce the reactance Xc, it is only necessary to increase the dielectric constant εg of the dielectric barrier 13, and it can be seen from the equation (1) that the thickness dg of the dielectric barrier 13 should be reduced.

From the above, in order to increase the efficiency of the ozone generator 10, it is important to shorten the discharge gap length d (the capacitance Ca of the discharge gap G is increased), and the thickness dg of the dielectric barrier 13 is reduced. It is important to make it thinner.
Specifically, the discharge gap length d is preferably d ≦ 0.6 mm from the viewpoint of ozone generation efficiency. The thickness dg of the dielectric barrier 13 is preferably dg <1.8 mm.

The relationship between the capacitance Cg of the dielectric and the capacitance Ca of the discharge gap G is Cg> Ca, so that the voltage applied between the discharge gaps G is applied to all the voltages applied by the high-voltage AC power supply 15. The ratio of the generated voltage is increased, the power factor of the high-voltage AC power supply 15 is improved, and the efficiency of the ozone generator 10 and thus the entire ozone generation system having the ozone generator 10 is improved.
As described above, according to the first embodiment, the power factor of the power source is improved, and the efficiency of the ozone generator, and thus the entire ozone generation system having the ozone generator, is improved.

[2] Second Embodiment FIG. 5 is a schematic configuration explanatory diagram of an ozone generator according to a second embodiment.
In FIG. 5, parts that are the same as in the first embodiment of FIG.
The ozone generator 10X of the embodiment is configured as a dielectric barrier discharge type ozone generator.

  The ozone generator 10X has a first electrode (power supply side electrode) 11X, which is a cylindrical dielectric electrode, and a cylinder in a state where a predetermined discharge gap G is maintained facing the outer peripheral surface of the dielectric electrode 11X. A second electrode 12X made of stainless steel is disposed. Between the back surface of the second electrode 12X and the airtight container 17, quartz having a small expansion coefficient is provided between the cooling water inlet pipe 22 into which cooling water is introduced and the cooling water outlet pipe 23 into which the cooling water CW is led out. A cylindrical dielectric 13X made of glass or the like is provided. A conductive electrode 13XA is formed on the inner peripheral surface of the cylindrical dielectric 13X. The conductive electrode 13XA is connected to a high voltage power supply terminal 13XB connected to a high voltage AC power supply 15 via an overcurrent interrupting element (for example, a fuse) 16.

Here, the cylindrical dielectric 13X is formed of quartz glass, borosilicate glass, high silicate glass, aluminum silicate glass, ceramics, or the like.
The conductive electrode 13XA is formed of gold, silver, copper, stainless steel, chromium, tin, zinc, nickel carbon or aluminum by sputtering, thermal spraying, vapor deposition, electroless plating, electrolytic plating, paint coating, or the like.

  Here, the second electrode 12X and the cylindrical dielectric 13X are separated by the discharge gap length d by the spacer 14 to form the discharge gap G. In this case, the spacer 14 is provided separately from the second electrode 12X. However, the spacer 14 may be configured to have a minute protrusion on the second electrode 12X.

  Further, the discharge gap length d is a desired value (for example, discharge gap length d = 0.3 mm to 0.00 mm) when the gas pressure (absolute pressure) of the supplied raw material gas is p. When the source gas is air, it is set to 7 to 16 kPa · cm).

  Also in the second embodiment, in order to increase the power factor of the discharge part, it is only necessary to decrease the reactance Xc. Therefore, in order to decrease the reactance Xc, the dielectric constant εg of the cylindrical dielectric 13X should be increased. What is necessary is just to reduce the thickness dg of the cylindrical dielectric 13X from the above-described equation (1).

  Further, in order to increase the efficiency of the ozone generator 10X, it is important to shorten the discharge gap length d (the capacitance Ca of the discharge gap G is increased).

  Specifically, the discharge gap length d is preferably d ≦ 0.6 mm from the viewpoint of ozone generation efficiency. The thickness dg of the cylindrical dielectric 13X is preferably dg <1.8 mm.

  The relationship between the capacitance Cg of the dielectric and the capacitance Ca of the discharge gap G is Cg> Ca, so that the voltage applied between the discharge gaps G is applied to all voltages applied by the high-voltage AC power supply 15. The ratio of the generated voltage is increased, the power factor of the high-voltage AC power supply 15 is improved, and the efficiency of the ozone generator 10X and thus the entire ozone generator system having the ozone generator 10X is improved.

  As described above, according to the second embodiment as well, the power factor of the power source is improved as in the first embodiment, and the efficiency of the ozone generator, and thus the entire ozone generation system having the ozone generator, is improved. To do.

[3] Modified Example of Embodiment [3.1] First Modified Example In each of the above embodiments, air is used as the raw material gas. Concentration ozone can be generated, and the efficiency of the ozone generation system can be improved.

[3.2] Second Modification In the above description, the reactance Xc is reduced by reducing the thickness dg of the dielectric barrier 13 or the cylindrical dielectric 13X. 13 or the thickness of the cylindrical dielectric 13X is limited in terms of withstand voltage, so that it can be understood from the above-described equation (1) instead of or in addition to reducing the thickness dg. In addition, the dielectric barrier 13 or the cylindrical dielectric 13X may have a high dielectric constant εg (specifically, a dielectric constant εg ≧ 6 is effective from the viewpoint of improving the power factor). Is possible.

[3.3] Third Modification In the first embodiment and the second embodiment described above, a configuration in which air, which is a raw material gas, is simply supplied from the outside of the ozone generator, but an evaporator is provided, It is also possible to supply oxygen gas obtained by vaporizing liquid oxygen as a raw material gas.

[3.4] Fourth Modification In the above description, a high-voltage AC power supply is used as the power supply, but a pulse power supply may be used.

  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, 10X Ozone generator 11 First electrode (plate electrode)
11X Dielectric electrode 12 Second electrode (Plate electrode)
12X Second electrode (cylindrical electrode)
13 Dielectric Barrier 13A Conductive Film 13X Cylindrical Dielectric 13XA Conductive Electrode (Cylinder Electrode)
13XB High-voltage power supply terminal 14 Spacer 15 High-voltage AC power supply 16 Overcurrent cutoff element 17 Airtight container 21 Gas inlet pipe 22 Cooling water inlet pipe 23 Cooling water outlet pipe 24 Gas outlet pipe

Claims (7)

An ozone generator for generating ozone by applying a predetermined high voltage between the first electrode and the second electrode via a dielectric and a discharge gap having a predetermined length to discharge the raw material gas flowing in the discharge gap. In
The dielectric capacitance Cg of the dielectric and the capacitance Ca of the discharge gap are:
Cg> Ca
The dielectric thickness and the discharge gap length are set so as to satisfy
Ozone generator. As the dielectric,
The dielectric capacitance Cg of the dielectric and the capacitance Ca of the discharge gap are:
Cg> Ca
Using a dielectric having a dielectric constant satisfying
The ozone generator according to claim 1. The first electrode and the second electrode are each configured as a plate electrode,
The ozone generator of Claim 1 or Claim 2. The first electrode is configured as a cylindrical electrode;
The second electrode is configured as a cylindrical electrode disposed coaxially with the first electrode.
The ozone generator of Claim 1 or Claim 2. The predetermined length is 0.6 mm or less,
The ozone generator in any one of Claim 1 thru | or 4. The predetermined length is more preferably 0.3 mm to 0.5 mm.
The ozone generator according to claim 5. The dielectric constant is 6 or more,
The ozone generator according to claim 2.

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