TW201309105A - Plasma generating method and generating device - Google Patents

Abstract

To provide a plasma generating method and a generating device that cause an electrical discharge to occur between a fluid and a dielectric tube. [Solution] A method for generating plasma with an electrical discharge within a dielectric tube by applying a voltage to a supplied gas, wherein: a water passage pipe is positioned within or above the dielectric tube; a high voltage electrode is arranged on the outer side of the dielectric tube; and a grounding electrode is arranged in a fluid that is discharged through the water passage pipe and into the dielectric tube while remaining at a distance from the inner perimeter of the dielectric tube. An electrical discharge is caused to occur either between the inner wall of the dielectric tube and the fluid, or between the inner wall of the dielectric tube and the water passage pipe, by applying a voltage to the high voltage electrode and the grounding electrode connected to a power source device. Additionally, the connections of the dielectric tube, the water passage pipe, and an inlet which introduces the supplied gas, is formed to have the structure of an aspirator.

Description

Plasma generation method and generating device

The present invention relates to a plasma generating method and a generating apparatus for causing a discharge between a fluid and a dielectric.

In recent years, deodorization of odor substances such as acetaldehyde, sulfur compounds, and nitrogen compounds has been carried out for the sterilization of bacteria, molds, and yeasts in sewage treatment facilities, chemical factories, pharmaceutical factories, and food factories. The ozone generating device is used to decolorize the excrement or the dye waste liquid or to make the harmful substances such as an organic solvent harmless.

This technique generally generates ozone in a discharge type ozone generator, and a gas-liquid mixing portion of a bubbler, an ejector, a static mixer or the like is mixed with water required for the treatment to bring the gas-liquid contact.

However, ozone is an allotrope of oxygen and is a very unstable gas, so it decomposes into oxygen at normal temperature. Therefore, it is difficult to store, and it is necessary to generate ozone at the same time as the treatment with chlorine, which has a problem of high processing cost.

For this problem, the proposal is to provide a high voltage electrode in the center of the porous ceramic tube, a gas passage between the porous ceramic tube and the high voltage electrode, and a ground electrode outside the porous ceramic tube, and porous here. The outer side of the ceramic tube directly forms a passage for the water to be treated, and a high-voltage high-frequency power source or a high-voltage pulse power source is connected between the high-voltage electrode and the ground electrode, thereby generating an ozone ozone water treatment device in the gas passage. ( For example, refer to Patent Document 1).

However, in the case of the above-described ozone water treatment device, a high-voltage electrode is provided in the center of the inside of the porous ceramic tube, and a high-voltage high-frequency power source or a high-voltage pulse power source is applied with a high voltage or a pulse high voltage, in order to cause stability. Discharge requires precise positioning of high voltage electrodes, dense dielectric coating of the electrode surface, and expensive pulse power.

In addition, it is proposed to provide a cavitation phenomenon generating unit that has a nozzle that reduces the inner diameter of the water passage in the subsequent stage of pressurizing the water to be treated, and that causes a cavitation bubble. And a counter electrode formed by the high-voltage side electrode and the ground-side electrode provided in the vicinity of the rear portion of the cavitation phenomenon generating portion, a high voltage is applied between the counter electrodes to cause discharge plasma to be generated, thereby performing the treated water The processor of the decomposition or synthesis of the substance to be treated, such as an organic substance, is disposed along the inner surface of the water passage in the cavitation generating portion so that the surface electrode can be formed on the surface of the pipe. (For example, refer to Patent Document 2).

However, in the case of the above-described plasma generating apparatus, the gas which is previously dissolved in the liquid to be treated generates bubbles by the phenomenon of air pockets, and it is difficult to arbitrarily adjust the amount of gas for discharging the gas-liquid interface, and degassing the liquid to be treated. When cavitation bubbles do not occur, and they do not discharge outside the area where cavitation bubbles are generated, there is a problem that it is difficult to enlarge.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] JP-A-2002-126769

[Patent Document 2] JP-A-2009-119347

In view of the above problems, the inventors of the present invention have conducted intensive studies to control the discharge of any fluid and arbitrary gas at an arbitrary flow rate by causing a fluid to pass through the dielectric tube. An aspirator structure is provided to provide a plasma generating method and a generating apparatus which can efficiently cause gas to dissolve in a gas while causing plasma to be generated in a gas phase and a liquid phase.

The plasma generating method and the generating apparatus of the present invention are a method of generating a plasma by applying a voltage to a gas to be supplied, and using a discharge in a dielectric tube. The first feature is a high voltage electrode system. Provided on the outer side of the dielectric tube, a fluid that is discharged into the dielectric tube in a state where a gap is formed on the inner circumference of the dielectric tube, and the ground electrode is disposed by the pair of power supply devices A high voltage electrode and the ground electrode apply a voltage to cause a discharge between the inner wall of the dielectric tube and the fluid.

Further, in a second feature, a water conduit for discharging a fluid to the dielectric tube is disposed inside or above the dielectric tube.

The plasma generating method of the present invention is a method for generating a plasma by applying a voltage to a gas to be supplied and using a discharge in a dielectric tube. According to a third aspect, the high-voltage electrode is disposed outside the dielectric tube, and a water conduit through which the fluid passes is disposed inside the dielectric tube, and a gap is formed in the inner circumference of the dielectric tube. A fluid is supplied from the water pipe to the dielectric tube, and a ground electrode is disposed on the inner wall of the dielectric tube by applying a voltage to the high voltage electrode and the ground electrode connected to the power supply device. Causes a discharge between the water pipes.

Further, the fourth feature is that the amount of the gas to be supplied and the amount of the fluid are 0.5 or less in the gas-liquid ratio, and the fifth feature is that the gas to be supplied is at least an oxygen-containing gas or an inert gas. One.

Further, the sixth feature is that the fluid that has passed through the discharge is used as a fluid that is again discharged into the dielectric tube or is returned to the upstream side of the water conduit to circulate the fluid. The seventh feature is that the fluid is circulated. The connection between the introduction port of the gas, the water supply pipe, and the introduction of the gas supplied to the inlet is a connection portion forming an aspirator structure, and the fluid discharged from the discharge port of the water pipe and the dielectric The internal gap of the mass tube generates a strong negative pressure, and the cavitation phenomenon is utilized to dissolve the gas generated by the discharge in the fluid. Further, the eighth feature is a plasma generating device comprising: a dielectric tube in which a high voltage electrode is disposed outside, a water pipe disposed inside or above the dielectric tube, and A ground electrode provided to contact the fluid discharged into the dielectric tube and a power supply device for connecting the high voltage electrode and the ground electrode in a state in which the inner circumference of the dielectric tube has a gap.

Further, a ninth feature is that the high voltage electrode is disposed in the dielectric In the outer side of the dielectric tube in a portion where the mass tube overlaps the water conduit, the tenth feature is that the ground electrode is disposed inside the dielectric tube or the fluid discharged from the dielectric tube.

Further, the eleventh feature is that the ground electrode is covered with an insulating compound, and the twelfth feature is that the insulating compound is glass.

Further, a thirteenth feature is that the dielectric tube is at least one of ceramic or glass.

Further, a fourteenth feature is that the water passage pipe is made of any one of ceramic, glass, resin, and metal, and the fifteenth feature is that the resin is a fluorine resin.

Further, the sixteenth feature is characterized in that the fluid that has passed through the portion that causes the discharge is returned to the upstream side of the water conduit to circulate the fluid, and the seventeenth feature is that the dielectric tube, the water conduit, and the The gas introduction port of the dielectric tube forms an aspirator structure.

According to the plasma generation method and the production apparatus of the present invention, the following good effects can be obtained.

(1) By using the plasma generating method and apparatus of the present invention, it is possible to irradiate the plasma corresponding to the treated fluid directly or in the vicinity of the fluid.

(2) A large amount of ozone can be generated by the oxygen supplied to the gas, and a large amount of ozone can be directly supplied to the fluid, and an active species such as an OH radical can be generated.

(3) by controlling the gas introduced into the dielectric tube and the gas The liquid ratio can efficiently dissolve the ozone gas generated by the discharge to the fluid.

(4) By forming the aspirator structure, a strong negative pressure is generated in the gap between the fluid discharged from the discharge port of the water pipe and the inside of the dielectric tube, and the ozone gas can be more efficiently performed by the cavitation phenomenon. Soluble in fluids.

(Embodiment 1)

Hereinafter, the first embodiment of the present invention will be described with reference to Figs. 2 and 8, but the present invention is of course not limited to the embodiment.

In Fig. 2, the plasma generating apparatus of the present invention comprises a dielectric tube 1, a water conduit 2, a high voltage electrode 3, a ground electrode 4, a power source 5, and a gas introduction tube 6, and forms an aspirator structure.

The dielectric tube 1 is a substantially cylindrical shape made of glass. The cross section of the dielectric tube 1 may be a quadrangular shape, a rhombic shape, or a polygonal shape. However, in terms of ease of arrangement of the high voltage electrode 3, it is preferably circular.

The water conduit 2 is located at the same center of the dielectric tube 1, and the discharge port of the water conduit 2 is disposed on the upstream side of the high voltage electrode 3 portion disposed on the dielectric tube 1. The cross section of the water pipe 2 is a quadrangular shape, a rhombus shape, or a polygonal shape. However, since the water pipe 2 functions as a dielectric material, it is preferably formed in the same shape as the dielectric material pipe 1 to enable the dielectric tube 1 to be The gap is formed uniformly.

The fluid introduced into the water conduit 2 may be supplied by pressure by a height difference or a pump or the like, and the fluid is a liquid or a liquid containing a liquid such as steam. . The introduced fluid passes through the inside of the dielectric tube 1 through the water pipe 2, but since the discharge plasma is caused between the inner wall of the dielectric tube 1 where the high voltage electrode 3 is disposed and the fluid, Therefore, it is preferable that the fluid is not attached to the inner wall of the dielectric tube 1 where the high voltage electrode 3 is disposed. However, even if the fluid adheres to the inner wall of the dielectric tube 1, the gas space is formed in the fluid by the introduction of the gas, so that the discharge plasma is caused.

The velocity of the fluid can be arbitrarily determined, and the flow rate corresponding to the purpose of the fluid to be treated can be formed in accordance with the discharge frequency calculated from the frequency of the power source 5 used. In order to dissolve a gas such as ozone generated by the discharge in the fluid, it is preferable that the ratio of the amount of the fluid to the gas is 0.5 or less. Further, by forming the aspirator structure as shown in Fig. 2, a strong negative pressure is generated in the internal space of the dielectric tube 1 by the fluid discharged from the discharge port of the water conduit 2, and the dissolution efficiency occurs by The cavitation phenomenon of the discharge port becomes large.

The high voltage electrode 3 is wound around the outside of the dielectric tube 1, and the ground electrode 4 is disposed at the inner center of the dielectric tube 1, and is connected to the power source 5, and the gas is introduced from the gas introduction tube 6, and the fluid is applied to the fluid. A voltage is applied, thereby causing a discharge in a circumferential manner between the inner wall of the dielectric tube 1 in which the high voltage electrode 3 is disposed and the fluid.

The ground electrode 4 is disposed inside the dielectric tube 1 as shown in FIG. 2 or is disposed in the fluid discharged from the dielectric tube 1 as shown in FIG. 8, but is disposed inside the dielectric tube 1. When the electrode 4 is grounded, since the gap between the high voltage electrode 3 and the ground electrode 4 is small, a strong electric field is generated and discharge is easy. However, for example, when a fluid having a large electrical conductivity is used like seawater, even if the ground electrode 4 is disposed in the fluid discharged from the dielectric tube 1, a strong electric field is generated and discharge is easy. Therefore, the position of the ground electrode 4 is determined as long as it depends on the nature of the fluid.

In addition, the material of the ground electrode 4 may be selected from a metal such as copper or stainless steel according to the nature of the fluid. However, if the metal component is eluted as in the case of cleaning the electronic component, it is difficult to cover the insulating compound with the ground electrode 4. It is preferable that the dielectric constant is low and the glass having less elution into the fluid is preferable.

The material of the dielectric tube 1 may be ceramic or glass having plasma resistance, heat resistance, and ozone resistance, and is preferably glass having a low dielectric constant.

The material of the water conduit 2 can be arbitrarily selected, and the material having a high insulating property can function as a dielectric material. Therefore, it can be arbitrarily selected according to the dielectric constant, but it is resistant to plasma and ozone. Ceramics, glass, and resins having good durability are preferred, and glass and fluorine-based resins are preferred. Further, a metal material having high conductivity can be used, and in the case of a metal material, a strong electric field is generated in the dielectric tube 1, so that it is easily discharged. Further, when the water conduit 2 is made of a metal material, the installation electrode 4 can be disposed in the water conduit 2 itself, and the trouble of production can be eliminated.

The introduced gas can be supplied by pressure by a blower, a gas cylinder, or the like, or can be supplied by a negative pressure generated when the fluid flows, and is introduced into the interior of the dielectric tube 1 through the gas introduction pipe 6 in either case. The gas can be arbitrarily determined according to the purpose of the fluid to be treated, but in order to generate an active species such as ozone or OH radical, it is a gas containing at least oxygen 7 can. Further, an inert gas may be used when the gas containing oxygen 7 is dissolved in the fluid to be introduced in advance.

(Embodiment 2)

Next, a second embodiment of the present invention will be described with reference to Figs. 4, 13, and 15. However, the present invention is of course not limited to the embodiment.

Since the configuration of the plasma generating apparatus is the same as that of the first embodiment, the description thereof is omitted.

As shown in Fig. 13, the water conduit 2 is located at the same center of the dielectric tube 1, and the discharge port of the water conduit 2 is disposed on the downstream side of the high voltage electrode 3 disposed on the dielectric tube 1. .

The plasma generating apparatus basically causes discharge between the inner wall of the dielectric tube 1 in which the high voltage electrode 3 is disposed and the fluid, but the fluid may not necessarily exist in the high voltage electrode 3 Part of the inner wall of the dielectric tube 1. Since the discharge is generated in the field where the electric field is strong, as shown in FIG. 13, as long as the discharge port of the water pipe 2 is disposed in the vicinity of the downstream of the inner wall of the dielectric tube 1 in which the high-voltage electrode 3 is disposed, it will be as shown in the figure. As shown in Fig. 15, a strong electric field is generated between the inner wall of the dielectric tube 1 and the fluid to cause discharge.

As shown in FIG. 4, when the discharge is caused by the inner wall of the fluid and the portion of the dielectric tube 1 where the high voltage electrode 3 is disposed, in order to strictly continue the stable discharge, the electric tube 1 and the fluid are required. Since it is kept at a certain interval, it is preferable to mount a rectifier inside the water pipe 2 or to provide a constant pressure valve or the like in the water pipe 2 . On the other hand, as shown in FIG. 15, a water pipe 2 is disposed in the vicinity of the downstream of the inner wall of the dielectric tube 1 in which the high voltage electrode 3 is disposed. When the discharge port causes the discharge to occur, since the discharge port of the water pipe 2 is fixed, the distance between the fluid and the inner wall of the dielectric tube 1 where the high voltage electrode 3 is disposed is fixed even in the water pipe 2 There is no rectifier or constant pressure valve, etc., and it is possible to continue the stable discharge between the inner wall of the dielectric tube 1 and the fluid. Further, when a sufficient voltage is applied to the dielectric tube 1, a strong electric field is generated inside the water conduit 2, and a gas-liquid interface is discharged between the gas and the liquid in the fluid.

In this case, the distance between the discharge port of the water pipe 2 and the inner wall of the dielectric tube 1 in which the high voltage electrode 3 is disposed must be the length of the discharge extension, but the length may depend on the inner diameter of the dielectric tube 1. The distance from the outer diameter of the water pipe 2 is determined. For example, when the interval between the inner diameter of the dielectric tube 1 and the outer diameter of the water pipe 2 is 0.5 mm, the discharge port of the water pipe 2 and the high voltage electrode 3 are disposed. When the distance of the inner wall of the dielectric tube 1 is within 20 mm, a discharge is caused between the inner wall of the dielectric tube 1 and the fluid discharged from the discharge port of the water tube 2. Further, when the water pipe 2 is made of a porous ceramic, the fluid oozes out from the porous hole, and causes an inner wall of the dielectric tube 1 where the high voltage electrode 3 is disposed and a fluid oozing from the porous body. Discharge, so the trouble of rectifying the fluid can be eliminated. The material of the water conduit 2 can be arbitrarily selected, and the material having a high insulating property can function as a dielectric material. Therefore, it can be arbitrarily selected according to the dielectric constant, but it is resistant to plasma and ozone. Ceramics, glass, and resins having good durability are preferred, and glass and fluorine-based resins are preferred. Further, a metal material having high conductivity can be used, and in the case of a metal material, a strong electric field is generated in the dielectric tube 1, so that it is easily discharged. In addition, when the water pipe 2 is made of a metal material, it is only necessary to set The electrode 4 is disposed in the water pipe 2 itself, which saves the trouble of production.

[Examples]

In the present invention, the above-described embodiment is used to carry out tests for photographing, ozone concentration, and dissolved ozone concentration during discharge. The measurement method of the test is shown below.

(1) Determination of ozone concentration

Gas phase ozone concentration meter: OZ-3O made by DKK-TOA CORPORATION

An ozone concentration sensor was inserted into the upper portion of the water tank and measured by a gas phase ozone concentration meter.

(2) Determination of dissolved ozone concentration

Dissolved Ozone Concentration Meter: OZ-2O by DKK-TOA CORPORATION

A dissolved ozone concentration sensor was placed in the circulation tank for measurement.

[Example 1]

A flow chart of the experimental setup is shown in FIG.

The experimental apparatus includes: a plasma generating device; a water receiving tank (water amount: 6 L), which receives treated water discharged from the plasma generating device, and an ozone concentration sensor on the upper surface of the water; Circulating tank (water quantity 2L), which is connected to the water receiving tank by a pipe, circulates tap water, and has a dissolved ozone concentration sensor at the lower part of the water surface, and is connected from the circulation tank to the plasma by a friction pump and a helium hose. The device is connected to the gas inlet of the plasma generating device and the oxygen cylinder by a nylon tube. As shown in Fig. 2, the main body of the plasma generator is made of glass, and an aspirator structure is formed. The water pipe 2 (outer diameter 7 mm, inner diameter 5 mm) is placed in the dielectric tube 1 (outer diameter 10 mm, inner diameter 8 mm). The upper portion of the concentric circle is wound around the dielectric tube 1 by a copper-belt high voltage electrode 3 having a width of 10 mm so as to be centered at a position 10 mm from the downstream side of the discharge port of the water pipe 2, and has a diameter of 1 mm. The ground electrode 4 made of stainless steel is inserted into the water pipe 2 and the dielectric tube 1 from the vicinity of the gas introduction port, and the high voltage electrode 3 and the ground electrode 4 are connected to the power source 5 to start the friction pump, and the flow rate is made at a flow rate of 8 L/min. On the other hand, the oxygen gas was introduced from the oxygen cylinder at an air flow rate of 3 L/min, and a voltage (9 kV, 6 kHz) was applied to discharge, and the discharge and the ozone concentration and the dissolved ozone concentration were observed. As a result, as shown in FIG. 3 (photograph) and FIG. 4 (schematic diagram), a purple discharge was observed between the inner wall of the dielectric tube 1 and the tap water. Further, when the discharge is caused by the presence of oxygen, ozone is known, and as evidence of the discharge, as shown in Fig. 5, the ozone concentration after 30 minutes from the start of discharge is 1000 ppm, and the dissolved ozone concentration is Formed 0.47 ppm.

[Embodiment 2]

As shown in Fig. 6, except that the tap water is continuously circulated through water, the gas flow rate of oxygen 7 is set to 4 L/min (gas-liquid ratio 0.5), and the same as in the first embodiment. The sample was measured and the dissolved ozone concentration was measured. As a result, as shown in Fig. 7, the ozone dissolution efficiency was 21%.

[Example 3]

The dissolved ozone concentration was measured in the same manner as in Example 2 except that the gas flow rate of oxygen 7 was changed to 2.4 Lmin. As a result, as shown in Fig. 7, the ozone dissolution efficiency was 27%.

[Example 4]

The dissolved ozone concentration was measured in the same manner as in Example 2 except that the gas flow rate of oxygen 7 was set to 0.8 Lmin. As a result, as shown in Fig. 7, the ozone dissolution efficiency was 48%.

[Example 5]

The dissolved ozone concentration was measured in the same manner as in Example 2 except that the gas flow rate of oxygen 7 was changed to 0.4 Lmin. As a result, as shown in Fig. 7, the ozone dissolution efficiency was 67%.

[Embodiment 6]

As shown in Fig. 8, the ground electrode 4 made of a stainless steel wire (diameter: 1 mm) was placed outside the water receiving tank, and the ozone concentration and the dissolved ozone concentration were measured in the same manner as in the first embodiment. As a result, as shown in Fig. 9, the concentration of generated ozone 30 minutes after the start of discharge was 527 ppm, and the concentration of dissolved ozone was 0.18 ppm.

[Embodiment 7]

The ozone concentration and the dissolved ozone concentration were measured in the same manner as in Example 1 except that the size of the water conduit 2 was set to (outer diameter: 7 mm, inner diameter: 6 mm) and the electrode was placed so as to cover the electrode with a thickness of 0.5 mm. As a result, as shown in FIG. 10, the generated ozone concentration 30 minutes after the start of discharge was 700 ppm, and the dissolved ozone concentration was 0.38 ppm.

[Embodiment 8]

The same procedure as in Example 1 was carried out except that the gas introduced into the plasma generating apparatus was argon gas. As a result, as shown in Fig. 11 (photograph) and Fig. 4 (schematic diagram), a purple discharge was observed between the inner wall of the dielectric tube 1 and the tap water.

[Embodiment 9]

In the same manner as in Example 1, except that the material of the water conduit 2 of the plasma generating apparatus was made of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) resin or stainless steel metal, as evidence of discharge, The concentration of ozone generated was measured. As a result, as shown in FIG. 12, the ozone concentration after 30 minutes from the start of discharge was 956 ppm and 1043 ppm, respectively.

[Embodiment 10]

As shown in FIG. 13 , the discharge port of the water pipe 2 is disposed 15 mm from the center portion of the high-voltage electrode 3 disposed in the dielectric tube 1 to the downstream side. Further, in the same manner as in Example 1, except that the introduction gas was argon, discharge was performed, and the discharge and the measured ozone concentration and the dissolved ozone concentration were observed. As a result, as shown in FIG. 14 (photograph) and FIG. 15 (schematic diagram), a purple discharge was observed between the inner wall of the dielectric tube 1 and the outer wall of the water conduit 2 and the tap water.

[Example 11]

In the same manner as in Example 10 except that the introduction gas was oxygen 7 and the methylene blue concentration was 5 mg/L, the cumulative change in the amount of generated ozone was shown in Fig. 16 and the amount of methylene blue was decolored. The duration changes are shown in Figure 17.

[Comparative Example 1]

The dissolved ozone concentration was measured in the same manner as in Example 1 except that the gas flow rate of oxygen 7 was 4.8 Lmin. As a result, as shown in Fig. 7, the ozone dissolution efficiency was 18%.

[Comparative Example 2]

In the same manner as in Example 11, except that the t-BuOH of the OH radical scavenger was added to 0.1 mM, the change in the cumulative amount of generated ozone was shown in Fig. 16, and the change in the amount of the methylene blue decolorization was shown in Fig. 17 . . As a result, although the generation of ozone is equivalent, the decolorization rate is lowered by the addition of t-BuOH, suggesting the formation of OH radicals in the plasma generating apparatus.

[Comparative Example 3]

In the same manner as in Example 11, except that t-BuOH of the OH radical scavenger was added to 1 mM, the change in the cumulative amount of generated ozone was shown in Fig. 16, and the change in the amount of decolorization of methylene blue was shown in Fig. 17. As a result, although the generation of ozone is equivalent, the decolorization rate is lowered by the addition of t-BuOH, suggesting the formation of OH radicals in the plasma generating apparatus.

[Comparative Example 4]

In the same manner as in Example 11, except that the t-BuOH of the OH radical scavenger was added to 10 mM, the change in the cumulative amount of generated ozone was shown in Fig. 16, and the change in the amount of decolorization of methylene blue was shown in Fig. 17. As a result, although the generation of ozone is equivalent, the decolorization rate is lowered by the addition of t-BuOH, suggesting the formation of OH radicals in the plasma generating apparatus.

[Embodiment 12]

As shown in Fig. 18, the main body of the plasma generator is formed of glass to form an aspirator structure, and the water pipe 2 (outer diameter 7 mm, inner diameter 5 mm) is placed in the dielectric tube 1 (outer diameter 10 mm, inner diameter) The upper portion of the concentric circle of 8 mm) is wound around the dielectric tube 1 with a diameter of 10 mm, and the diameter of the copper tube high voltage electrode 3 having a width of 10 mm is formed so as to be centered at a position 25 mm from the upstream side of the discharge port of the water pipe 2 A 1mm stainless steel ground electrode 4 is inserted into the water pipe 2 and the dielectric tube 1 from the vicinity of the gas inlet, and the high voltage is electrically The pole 3 and the ground electrode 4 are connected to the power source 5, the friction pump is started, the tap water is circulated at a flow rate of 8 L/min, and the voltage is applied while introducing oxygen 7 from the oxygen cylinder at a gas flow rate of 3 L/min ( 9kV, 6kHz) discharge, observe the discharge and determine the ozone concentration and dissolved ozone concentration. As a result, as shown in FIG. 19 (photograph) and FIG. 20 (schematic diagram), a purple discharge was observed between the inner wall of the dielectric tube 1 and the tap water. Further, when the discharge is caused by the presence of oxygen, ozone is known, and as evidence of the discharge, as shown in Fig. 21, the ozone concentration after 30 minutes from the start of discharge is 990 ppm, and the dissolved ozone concentration is Formed at 0.45 ppm.

[Example 13]

As shown in Fig. 6, the dissolved ozone concentration was measured in the same manner as in Example 1 except that the flow rate of the oxygen gas 7 was 4 L/min (gas-liquid ratio 0.5) without continuously flowing water through the circulation of the tap water. As a result, as shown in Fig. 22, the ozone dissolution efficiency was 21%.

[Embodiment 14]

The dissolved ozone concentration was measured in the same manner as in Example 13 except that the gas flow rate of oxygen 7 was changed to 2.4 Lmin. As a result, as shown in Fig. 22, the ozone dissolution efficiency was 26%.

[Example 15]

Except for setting the gas flow rate of oxygen 7 to 0.8 Lmin, and examples 13 was also carried out, and the dissolved ozone concentration was measured. As a result, as shown in Fig. 22, the ozone dissolution efficiency was 50%.

[Example 16]

The dissolved ozone concentration was measured in the same manner as in Example 13 except that the gas flow rate of oxygen 7 was changed to 0.4 Lmin. As a result, as shown in Fig. 22, the ozone dissolution efficiency was 73%.

[Example 17]

As shown in Fig. 23, the ground electrode 4 made of a stainless steel wire (diameter: 1 mm) was placed in the water receiving tank, and the ozone concentration and the dissolved ozone concentration were measured in the same manner as in the example 12. As a result, as shown in Fig. 24, the concentration of generated ozone 30 minutes after the start of discharge was 534 ppm, and the concentration of dissolved ozone was 0.19 ppm.

[Embodiment 18]

The ozone concentration was measured in the same manner as in Example 12 except that the size of the water conduit 2 was (outer diameter: 7 mm, inner diameter: 6 mm) and the electrode was placed so as to cover the electrode with a thickness of 0.5 mm. As a result, as shown in FIG. 25, the concentration of generated ozone 30 minutes after the start of discharge was 685 ppm, and the concentration of dissolved ozone was 0.37 ppm.

[Embodiment 19]

In addition to setting the gas introduced into the plasma generating device to argon gas, Example 12 was carried out in the same manner. As a result, as shown in Fig. 26 (photograph) and Fig. 20 (schematic diagram), a purple discharge was observed between the inner wall of the dielectric tube 1 and the outer wall of the water tube 2.

[Example 20]

In the same manner as in Example 12 except that the material of the water conduit 2 of the plasma generating apparatus was made of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) resin or stainless steel metal, as evidence of discharge, The concentration of ozone generated was measured. As a result, as shown in FIG. 27, the ozone concentration after 30 minutes from the start of discharge was 281 ppm and 348 ppm, respectively.

[Comparative Example 5]

The dissolved ozone concentration was measured in the same manner as in Example 1 except that the gas flow rate of oxygen 7 was 4.8 Lmin. As a result, as shown in Fig. 22, the ozone dissolution efficiency was 17%.

1‧‧‧ dielectric tube

2‧‧‧Water pipes

3‧‧‧High voltage electrode

4‧‧‧Ground electrode

5‧‧‧Power supply

6‧‧‧ gas introduction tube

7‧‧‧Oxygen

Fig. 1 is a flow chart showing an experimental apparatus according to a first embodiment of the present invention.

Fig. 2 is a view showing a plasma generating apparatus according to a first embodiment of the present invention.

Fig. 3 is a photograph showing the results of experiments in the first embodiment of the present invention.

Fig. 4 is a schematic view showing a plasma generating apparatus according to a second embodiment of the present invention.

Fig. 5 is a graph showing the transition of the generated ozone concentration and the dissolved ozone concentration in each discharge time in the first embodiment.

Fig. 6 is a flow chart of the experimental apparatus of the first embodiment.

Fig. 7 is a graph showing the relationship between the gas-liquid ratio and the dissolution efficiency of Examples 2 to 5 and Comparative Example 1 of the present invention.

Fig. 8 is a view showing a plasma generating apparatus of a sixth embodiment.

Fig. 9 is a graph showing the transition of the generated ozone concentration and the dissolved ozone concentration in each discharge time in the sixth embodiment.

FIG. 10 is a graph showing the transition of the generated ozone concentration and the dissolved ozone concentration in each discharge time in Example 7. FIG.

Fig. 11 is a photograph showing the results of the experiment of Example 8.

Fig. 12 is a graph showing the transition of the generated ozone concentration for each discharge time in the ninth embodiment.

Fig. 13 is a view showing a plasma generating apparatus of a tenth embodiment.

Fig. 14 is a photograph showing the results of the experiment of Example 10.

Fig. 15 is a schematic diagram of a generating apparatus of the tenth embodiment.

16 is a graph showing transitions of the amount of generated ozone in each discharge time in Example 11 and Comparative Example 2 to Comparative Example 4. FIG.

17 is a graph showing the transition of the amount of methylene blue decolorization for each discharge time in Example 11 and Comparative Example 2 to Comparative Example 4. FIG.

Fig. 18 is a view showing a plasma generating apparatus of a twelfth embodiment.

Fig. 19 is a photograph showing the results of the experiment of Example 12.

Fig. 20 is a schematic view showing a plasma generating apparatus of a twelfth embodiment.

Figure 21 is a graph showing the generation of ozone concentration for each discharge time in Example 12. And a chart of the shift of dissolved ozone concentration.

Fig. 22 is a graph showing the relationship between the gas-liquid ratio and the dissolution efficiency of Examples 13 to 16 and Comparative Example 5 of the present invention.

Fig. 23 is a view showing the plasma generating apparatus of the seventeenth embodiment.

Fig. 24 is a graph showing the transition of the generated ozone concentration and the dissolved ozone concentration in each discharge time in Example 17.

Fig. 25 is a graph showing the transition of the generated ozone concentration and the dissolved ozone concentration in each discharge time in Example 18.

Fig. 26 is a photograph showing the results of the experiment of Example 19.

Fig. 27 is a graph showing the transition of the generated ozone concentration for each discharge time in Example 20.

Claims (17)

A plasma generation method is a method for generating a plasma by applying a voltage to a gas to be supplied, and discharging is performed by using a discharge in a dielectric tube, wherein a high voltage electrode is disposed in the dielectric tube On the outer side of the dielectric tube, a fluid is discharged into the dielectric tube with a gap in the inner circumference of the dielectric tube, and the ground electrode is connected to the high voltage electrode and the ground electrode connected to the power supply device. A voltage is applied to cause a discharge between the inner wall of the dielectric tube and the fluid. The plasma generation method according to claim 1, wherein the water conduit for discharging the fluid to the dielectric tube is disposed inside or above the dielectric tube. A plasma generation method is a method for generating a plasma by applying a voltage to a gas to be supplied, and discharging is performed by using a discharge in a dielectric tube, wherein a high voltage electrode is disposed in the dielectric tube The outside of the dielectric tube is provided with a water pipe through which the fluid passes, and a ground electrode is disposed in the fluid discharged into the dielectric tube through the water pipe while the inner circumference of the dielectric tube has a gap. A discharge is caused between the inner wall of the dielectric tube and the water conduit by applying a voltage to the high voltage electrode connected to the power supply device and the ground electrode. The plasma generation method according to any one of the first to third aspect, wherein the amount of the gas to be supplied and the amount of the fluid are 0.5 or less in a gas-liquid ratio. The plasma generation method according to any one of claims 1 to 4, wherein the gas to be supplied is at least one of an oxygen-containing gas and an inert gas. The method for producing a plasma according to any one of claims 1 to 4, wherein the fluid that has passed through the discharge is used as a fluid that is discharged into the dielectric tube again or again. The upstream side of the water pipe is returned to circulate the fluid. The method for producing a plasma according to any one of the first to sixth aspects of the present invention, wherein the dielectric tube, the water conduit, and the introduction port of the gas to be supplied are connected to form a suction. The connecting portion of the gas structure generates a strong negative pressure in the gap between the fluid discharged from the discharge port of the water pipe and the inside of the dielectric tube, and dissolves the gas generated by the discharge by the cavitation phenomenon. fluid. A plasma generating device characterized by: a dielectric tube having a high voltage electrode disposed outside, a water conduit disposed inside or above the dielectric tube, and a dielectric tube disposed in the dielectric tube A ground electrode provided to contact the fluid discharged into the dielectric tube and a power supply device connecting the high voltage electrode and the ground electrode in a state where the inner circumference has a gap. The plasma generating apparatus according to claim 8, wherein the high voltage electrode is disposed outside the dielectric tube in a portion where the dielectric tube overlaps the water tube. The plasma generating apparatus according to claim 8 or 9, wherein the ground electrode is disposed inside the dielectric tube or the fluid discharged from the dielectric tube. The plasma generating apparatus according to any one of claims 8 to 10, wherein the ground electrode is covered with an insulating compound. The plasma generating apparatus of claim 11, wherein the insulating compound is glass. The plasma generating apparatus according to any one of claims 8 to 12, wherein the dielectric tube is at least one of ceramic or glass. The plasma generating apparatus according to any one of claims 8 to 13, wherein the water conduit is made of any one of ceramic, glass, resin, and metal. The plasma generating apparatus of claim 14, wherein the resin is a fluorine-based resin. The plasma generating apparatus according to any one of the above-mentioned claims, wherein the fluid that has passed through the discharge is returned to the upstream side of the water pipe to circulate the fluid. The plasma generating apparatus according to any one of the preceding claims, wherein the dielectric tube, the water conduit, and the gas introduction port provided in the dielectric tube form an aspirator structure. .