JP6832571B2 - Liquid processing equipment - Google Patents

Description

The present disclosure relates to a liquid processing apparatus using plasma.

Conventionally, a technique of using plasma for purifying or sterilizing a liquid is known. For example, Patent Document 1 and Patent Document 2 describe a liquid processing apparatus that supplies a gas into a liquid and generates plasma in the supplied gas.

JP-A-2015-33694 Japanese Unexamined Patent Publication No. 2015-136644

The inventor of the present application has discovered a problem of precipitation of silicon oxide, which has not been considered in the conventional liquid processing apparatus. The present disclosure provides a liquid processing apparatus capable of suppressing the precipitation of silicon oxide and generating plasma more stably.

In order to solve the above problems, the liquid treatment apparatus according to one aspect of the present disclosure has a tubular first insulation having a first opening and a first inner surface for releasing a gas into the liquid to be treated. A body, a first electrode in which at least a part is arranged in a first space surrounded by the first inner surface, and a second electrode in which at least a part is arranged in the liquid to be treated. A gas supply device that discharges the gas into the liquid to be treated through the first opening by supplying the gas into the first space, and the first electrode and the second electrode. It is equipped with a power supply that generates plasma by applying a voltage between the and. The first inner surface includes a first partial region in contact with the first opening. The tip of the first electrode projects from the first opening to the outside of the first space, or recedes from the first opening into the first space by less than 3 mm. The first distance, which is the shortest distance between the side surface of the first electrode and the first partial region, is 1 mm or more.

According to the present disclosure, it is possible to provide a liquid processing apparatus capable of suppressing the precipitation of silicon oxide and generating plasma more stably.

FIG. 1 is a diagram showing the results of observing the precipitates adhering to the insulator from the opening side of the insulator. FIG. 2 is a diagram showing the analysis results of the precipitates adhering to the insulator shown in FIG. FIG. 3 is a diagram showing a configuration of a liquid processing apparatus according to the first embodiment. FIG. 4A is a cross-sectional view showing an example of the first electrode according to the first embodiment. FIG. 4B is a cross-sectional view showing another example of the first electrode according to the first embodiment. FIG. 5 is a cross-sectional view showing an example of the second electrode according to the first embodiment. FIG. 6 is a diagram showing the results of observing the first electrode and the insulator according to the first embodiment from the opening side. FIG. 7 is a diagram showing the stability of the plasma with respect to the distance between the first electrode and the insulator according to the first embodiment and the amount of receding of the end face of the first electrode. FIG. 8 is a diagram showing the results of observing the first electrode and the insulator from the opening side when the distance shown in FIG. 7 is 1.1 mm and the amount of retreat is 4 mm. FIG. 9 is a diagram showing the stability of the plasma with respect to the amount of retreat of the end face of the first electrode according to the first embodiment and the air flow rate. FIG. 10A is a diagram showing the results of observing the first electrode and the insulator from the side when the retreat amount shown in FIG. 9 is 4 mm and the air flow rate is 0.3 L / min. FIG. 10B is a diagram showing the results of observing the first electrode and the insulator from the side when the retreat amount shown in FIG. 9 is 4 mm and the air flow rate is 1.0 L / min. FIG. 11 is a diagram showing the configuration of the liquid processing apparatus according to the second embodiment. FIG. 12 is a diagram showing the result of observing the second insulator of the liquid processing apparatus according to the second embodiment from the side. FIG. 13 is a diagram showing the results of observing the first insulator of the liquid processing apparatus according to the second embodiment from the side. FIG. 14 shows the result of simulating the relationship between the second distance between the first electrode and the second insulator according to the second embodiment and the electric field value generated on the inner surface of the second insulator. It is a figure which shows. FIG. 15 is a diagram showing the configuration of the liquid processing apparatus according to the third embodiment. FIG. 16 is a cross-sectional view showing an example of the first electrode and the insulator according to the third embodiment. FIG. 17 is a front view of the first electrode and insulator according to the third embodiment when viewed from the tip side. FIG. 18 is a diagram showing the result of simulating the position of the gas-liquid interface in the vicinity of the insulator according to the comparative example of the third embodiment. FIG. 19 is a diagram showing a gas flow velocity distribution in the same simulation as in FIG. FIG. 20 is a diagram showing the result of simulating the position of the gas-liquid interface in the vicinity of the insulator according to the third embodiment. FIG. 21 is a diagram showing a gas flow velocity distribution in the same simulation as in FIG. FIG. 22 is a cross-sectional view showing the vicinity of the first electrode and the insulator of the liquid processing apparatus according to the modified example of the third embodiment.

(Background to obtain one aspect of the present disclosure)
The inventor of the present application has confirmed that when tap water is treated using a conventional liquid treatment device, the discharge becomes unstable in about 3 minutes after the start of the discharge. In addition, 5 minutes after the start of the discharge, it was visually confirmed that the precipitate had adhered to the vicinity of the opening of the insulator.

FIG. 1 is a diagram showing the results of observing the precipitate 90x adhering to the insulator 50x from the opening side of the insulator 50x. In FIG. 1, a white or gray substantially annular ring having a predetermined width indicates the approximate shape of the insulator 50x. Since the first electrode 30x is located behind the opening of the insulator 50x, it was not captured in the image shown in FIG. Therefore, the approximate shape of the first electrode 30x when viewed from the opening side is shown by a white broken line circle. These are the same in FIGS. 6 and 8 described later.

The inner diameter of the insulator 50x is 1 mm, and the outer diameter of the first electrode 30x is 0.8 mm. Therefore, the distance between the side surface of the first electrode 30x and the inner surface surface of the insulator 50x, that is, the width d1 of the space 52x is 0.1 mm. In this case, as shown in FIG. 1, it can be seen that the precipitate 90x is attached to the inner surface near the opening of the insulator 50x.

FIG. 2 is a diagram showing the analysis results of the precipitate 90x adhering to the insulator 50x shown in FIG. Specifically, FIG. 2 shows the results of analysis of the precipitate 90x by EDX (Energy Dispersive X-ray) analysis of SEM (Scanning Electron Microscope). In FIG. 2, the horizontal axis is the energy of the characteristic X-ray, and the vertical axis is the intensity (count value) thereof.

As shown in FIG. 2, it can be seen _{that the precipitate 90x is a compound of silicon oxide (SiO x).} The inventor of the present application examined the factors that cause the precipitate 90x to adhere to the inner surface of the insulator 50x as follows.

In the first electrode 30x and the insulator 50x shown in FIG. 1, the width d1 of the space 52x is about 0.1 mm. That is, since the first electrode 30x and the insulator 50x are close to each other, a dielectric barrier discharge or a creepage discharge occurs between the first electrode 30x and the insulator 50x. It is considered that the silica contained in tap water was deposited on the inner surface of the insulator 50x by exposing the surface of the insulator 50x to the plasma generated by these discharges. That is, the precipitate 90x is considered to be a substance formed by precipitating silica contained in tap water.

When the precipitate 90x is formed in the vicinity of the opening, a discharge may occur between the precipitate 90x and the first electrode 30x. Therefore, the voltage used for the discharge generated between the first electrode 30x and the second electrode (not shown) changes, and the plasma may become unstable.

Therefore, in order to solve the above problems, the liquid treatment apparatus according to one aspect of the present disclosure includes a first electrode and a second electrode in which at least a part thereof is arranged in the liquid to be treated, and the first electrode. By supplying gas to the first tubular insulator and the first insulator, which are arranged so as to surround the side surface with a space and have an opening at the end surface in contact with the liquid to be treated. A gas supply device that discharges the gas into the liquid to be treated through the opening, and a power source that generates plasma by applying a voltage between the first electrode and the second electrode. The distance between the side surface of the first electrode and the inner surface of the first insulator is 1 mm or more.

As a result, the distance between the side surface of the first electrode and the inner surface surface of the first insulator is 1 mm or more, so that the dielectric barrier discharge or creepage between the first electrode and the first insulator Discharge is less likely to occur. For this reason, the surface of the first insulator is less exposed to the plasma generated when these discharges occur, so that precipitates such as silica adhere to the inner surface of the first insulator. It is suppressed.

Further, for example, the first distance may be 1 mm or more and 3 mm or less.

As a result, the distance between the side surface of the first electrode and the inner surface surface of the first insulator is 3 mm or less and is not too far apart, so that the supplied gas can easily cover the first electrode. Therefore, the liquid processing apparatus according to one aspect of the present disclosure can generate more stable discharge and more stable plasma.

Further, for example, the end face of the first electrode may be retracted or protruded from the opening of the first insulator by 0 mm or more and 3 mm or less.

As a result, electric discharge is likely to occur between the end face of the first electrode and the gas-liquid interface, and it is possible to suppress the generation of electric discharge between the first electrode and the first insulator. Therefore, since the generation of precipitates such as silica can be suppressed, the liquid treatment apparatus according to one aspect of the present disclosure can generate more stable discharge and more stable plasma.

Further, the volume of the discharge generated between the first electrode and the gas-liquid interface can be controlled by the flow rate of the supplied gas. Therefore, for example, in the liquid processing apparatus according to one aspect of the present disclosure, the flow rate of the gas supplied by the gas supply apparatus may be 0.5 L / min or more.

As a result, as the flow rate of the gas increases, it is possible to suppress the discharge from spreading toward the inner surface of the first insulator, so that the surface of the first insulator is less likely to be exposed to plasma. Therefore, since the generation of precipitates such as silica can be suppressed, the liquid treatment apparatus according to one aspect of the present disclosure can generate more stable discharge and more stable plasma.

Further, for example, the first electrode has a long columnar electrode portion, and the first insulator is a long cylindrical body surrounding the side surface of the electrode portion, and the electrode portion and the electrode portion. The first insulator may be arranged coaxially with the first insulator.

As a result, a space having a uniform width is formed between the electrode portion and the first insulator, so that the surface of the first insulator is less likely to be exposed to plasma. Further, since the amount of gas flowing in the space can be made uniform, the liquid processing apparatus according to one aspect of the present disclosure can generate plasma more stably.

By the way, when a gas travels in a predetermined flow path, if the flow path width of the gas changes, the flow velocity of the gas changes locally, and the change may cause a swirling flow. When a swirling flow is generated inside the first insulator, the liquid may be drawn into the first insulator through the opening of the first insulator.

On the other hand, in the liquid processing apparatus according to one aspect of the present disclosure, for example, the first electrode is provided on a long columnar electrode portion and a rear end side of the electrode portion, and the electrode portion is provided. The support portion has a columnar support portion thicker than the electrode portion, and the support portion is provided with a gas supply hole through which the gas supplied by the gas supply device passes, and the gas is provided. The opening width of the supply hole and the inner diameter of the first insulator may be substantially the same.

As a result, when the gas supplied by the gas supply device enters the inside of the first insulator through the gas supply hole, the width of the gas flow path between the gas supply hole and the first insulator is substantially reduced. Can be uniform. Therefore, it is possible to suppress the generation of a swirling flow of gas inside the first insulator, and it is possible to generate plasma more stably.

Further, for example, an introduction port provided on the rear end side of the first insulator for introducing the gas supplied by the gas supply device into the inside of the first insulator is provided, and the introduction port is provided. The inflow direction of the gas as it passes may intersect the axial direction of the first insulator.

As a result, the gas introduced from the introduction port travels in the direction intersecting the axial direction, hits the inner surface of the first insulator, and then travels along the inside of the first insulator along the axial direction. To do. In this way, by changing the traveling direction once depending on the inner surface or the like, the gas can flow at a stable flow velocity along the axial direction in the vicinity of the opening of the first insulator. Therefore, it is possible to suppress the generation of a swirling flow of gas inside the first insulator, and it is possible to generate plasma more stably.

Further, for example, the bottomed cylinder portion having an opening width substantially the same as that of the first insulator is further provided, and the bottomed cylinder portion is located coaxially with the first insulator. It is connected to the rear end side of the first insulator, the introduction port is provided on the side wall of the bottomed tubular body portion, and the inflow direction of the gas when passing through the introduction port is the first insulation. It may be substantially orthogonal to the axial direction of the body.

As a result, the gas introduced from the introduction port travels in the direction orthogonal to the axial direction, hits the side wall of the bottomed cylinder portion, and then travels along the axial direction inside the first insulator. .. In this way, by changing the traveling direction once by the side wall or the like, the gas can flow in the first insulating body at a stable flow velocity along the axial direction. Therefore, it is possible to suppress the generation of a swirling flow of gas inside the first insulator, and it is possible to generate plasma more stably.

Further, when a voltage is applied to the first electrode surrounded by the first tubular insulator through the space, the gas-liquid interface (gas and liquid to be treated) near the opening of the first insulator Maxwell stress is applied to the interface) according to the strength of the electric field generated at the interface. Therefore, the liquid to be treated may infiltrate through the opening of the first insulator along the inner surface. As a result, the liquid to be treated may infiltrate the inside of the first insulator.

Therefore, in the liquid processing apparatus according to one aspect of the present disclosure, for example, a tubular second insulator which is arranged so as to surround the side surface of the first electrode with a space is further provided. The insulator is connected to the rear end side of the first insulator so that the insides of the second insulator and the first insulator communicate with each other, and the side surface of the first electrode is connected. The second distance, which is the distance between the second insulator and the inner surface of the second insulator, may be larger than the first distance.

As a result, the electric field generated between the inner surface of the second insulator and the first electrode is smaller than the electric field generated between the inner surface of the first insulator and the first electrode. The liquid to be treated that has penetrated into the inside of the insulator is less likely to penetrate into the inside of the second insulator. Therefore, according to the liquid processing apparatus according to one aspect of the present disclosure, plasma can be generated more stably.

Further, for example, the second distance is a distance determined according to the value of the voltage applied by the power supply, and the electric field generated on the inner surface of the second insulator by the voltage is equal to or less than a predetermined value. The distance may be.

This makes it possible to design the second insulator to an appropriate size according to the voltage applied between the first electrode and the second electrode. Therefore, for example, it is possible to avoid using a second insulator that is larger than necessary, so that it is possible to realize miniaturization, weight reduction, and cost reduction of the liquid processing apparatus.

Further, for example, the value of the voltage applied between the first electrode and the second electrode may be 5 kV or less, and the second distance may be 2.6 mm or more.

As a result, when the applied voltage is 5 kV or less, it is possible to suppress the infiltration of the liquid to be treated into the inside of the second insulator.

Further, for example, the value of the voltage applied between the first electrode and the second electrode may be 5 kV or more, and the second distance may be 5 mm or more.

As a result, when the applied voltage is 5 kV or more, it is possible to suppress the infiltration of the liquid to be treated into the inside of the second insulator.

Further, for example, the first electrode has a long columnar electrode portion, and the first insulator is a cylindrical body surrounding a side surface on the tip end side of the electrode portion, and the second insulator is used. The insulator is a tubular body that surrounds the side surface of the electrode portion on the rear end side, and the electrode portion, the first insulator, and the second insulator may be arranged coaxially. Further, for example, the second insulator may be a cylinder or a square cylinder.

As a result, a space having a uniform width is formed between the electrode portion and the first insulator and between the electrode portion and the second insulator, respectively. The strength of the electric field can be made uniform. Therefore, it is difficult for a portion where the electric field becomes strong locally to occur, so that it is possible to suppress the infiltration of the liquid to be treated into the inside of the second insulator. Therefore, the liquid processing apparatus according to one aspect of the present disclosure can generate plasma more stably.

Further, for example, the first insulator and the second insulator may be made of different materials.

Thereby, the workability of each of the first insulator and the second insulator can be improved. Therefore, for example, each of the first insulator and the second insulator can be precisely formed, so that the reliability of the liquid processing apparatus can be improved.

Further, for example, the first insulator and the second insulator may be integrally made of the same material as each other.

As a result, the number of parts can be reduced, so that the weight of the liquid processing apparatus can be reduced. Further, in the manufacturing method of the liquid processing apparatus, the number of steps of the parts assembling process can be reduced, so that the cost can be reduced.

Further, in the liquid treatment apparatus according to another aspect of the present disclosure, for example, a tubular first insulator having a first opening and a first inner side surface for discharging a gas into the liquid to be treated. The first electrode, which is at least partially arranged in the first space surrounded by the first inner surface, the second electrode, which is at least partially arranged in the liquid to be treated, and the first electrode. A gas supply device that discharges the gas into the liquid to be treated through the first opening by supplying the gas into the space of 1, and the first electrode and the second electrode. It is equipped with a power supply that generates plasma by applying a voltage between them. The first inner surface includes a first partial region in contact with the first opening. The tip of the first electrode projects from the first opening to the outside of the first space, or recedes from the first opening into the first space by less than 3 mm. The first distance, which is the shortest distance between the side surface of the first electrode and the first partial region, is 1 mm or more.

As a result, the shortest distance between the side surface of the first electrode and the first partial region becomes 1 mm or more, so that a dielectric barrier discharge or a creepage discharge is performed between the first electrode and the first insulator. Etc. are less likely to occur. For this reason, the surface of the first insulator is less exposed to the plasma generated when these discharges occur, so that precipitates such as silica adhere to the inner surface of the first insulator. It is suppressed.

In this specification, the "cylindrical shape" may be a cylindrical shape, a polygonal tubular shape, or a funnel shape. Further, the tubular shape may or may not be rotationally symmetric. The outer shape of the first insulator may be the same as or different from the shape of the first space. For example, the outer shape of the first insulator may be cylindrical, and the shape of the first space may be polygonal. On the contrary, the outer shape of the first insulator may be a polygonal columnar shape, and the shape of the first space may be a columnar shape. Further, the first electrode may be columnar, polygonal columnar or conical. When the shape of the first electrode, the shape of the outside of the first insulator, and the shape of the first space each have a central axis in the longitudinal direction, these central axes may coincide with each other, and one You don't have to.

The first opening may be downward and expel gas downward. Also, the first opening may be upward and expel gas upwards. In addition, the first opening may point in another direction and release the gas in that direction.

Further, the first partial region may be a ring-shaped region within a predetermined distance (for example, 4 mm) from the first opening in the first inner surface surface.

Further, for example, the tip of the first electrode may protrude from the first opening to the outside of the first space.

In the prior art, the discharge start voltage of the glow discharge is lowered by using the dielectric barrier discharge or the creepage discharge as an auxiliary discharge, but in this embodiment, the dielectric barrier discharge or the creepage discharge is less likely to occur. However, since the tip of the first electrode projects outward, the glow discharge can be started even when there is no or weak auxiliary discharge.

Further, for example, the tip of the first electrode may protrude from the first opening by 1 mm or more to the outside of the first space.

Further, for example, the tip of the first electrode may project from the first opening to the outside of the first space by 3 mm or less.

As a result, the entire protruding portion of the first electrode can be more reliably covered with bubbles, and plasma can be generated more stably.

Further, for example, the first inner surface surface may include a second partial region surrounding the first electrode, unlike the first partial region. The first distance, or the shortest distance between the side surface of the first electrode and the second subregion, is that the electric field generated in the first or second subregion by the voltage is 1.6 × 10. ^The distance may be 6 V / m or less.

Further, for example, the shortest distance between the first distance or the side surface of the first electrode and the second partial region may be 2.6 mm or more.

Further, for example, the shortest distance between the first distance or the side surface of the first electrode and the second partial region may be 5 mm or more.

Further, the first distance may be 10 mm or less. Thereby, bubbles can be generated more appropriately.

Further, for example, the flow rate of the gas supplied by the gas supply device may be 0.5 L / min or more.

Further, for example, the first electrode may include a long columnar electrode portion. The first insulator may be a long cylinder that surrounds the side surface of the electrode portion. The electrode portion and the first insulator may be arranged coaxially.

Further, for example, the first electrode is provided on a long columnar electrode portion having a tip on the downstream side and a rear end on the upstream side of the gas flow and on the rear end side of the electrode portion. A support portion that supports the electrode portion may be provided. The support portion may be a columnar shape thicker than the electrode portion. The first insulator may be a cylindrical body. The support portion may be provided with a gas supply hole through which the gas supplied by the gas supply device passes. The opening width of the gas supply hole and the inner diameter of the first insulator may be substantially the same.

Further, for example, the liquid processing apparatus of this embodiment may further include a pipe having an introduction port for introducing the gas supplied by the gas supply apparatus into the first space. The inflow direction of the gas when passing through the introduction port may intersect the axial direction of the first insulator.

Further, for example, the liquid processing apparatus of this embodiment may further include a tubular body having a third opening and a closed end on the opposite side of the third opening. The first insulator may have a second opening on the opposite side of the first opening. The opening width of the third opening may be substantially the same as the opening width of the second opening. The third opening and the second opening may be connected so that the cylinder is located coaxially with the first insulator. The introduction port may be provided on the side wall of the cylinder.

Further, for example, the liquid processing apparatus of this embodiment further includes a tubular second insulator having a second inner side surface portion that surrounds the side surface of the first electrode with a second space. May be good. The first insulator may have a second opening on the opposite side of the first opening. The second insulator may be connected to the second opening side of the first insulator so that the second space and the first space communicate with each other. The second distance, which is the shortest distance between the side surface of the first electrode and the second inner side surface portion, may be larger than the first distance.

The outer shape of the second insulator may be the same as or different from the shape of the second space. For example, the outer shape of the second insulator may be columnar, and the shape of the second space may be polygonal. On the contrary, the outer shape of the second insulator may be a polygonal columnar shape, and the shape of the second space may be a columnar shape. When the shape of the first electrode, the shape of the outside of the second insulator, and the shape of the second space each have a central axis in the longitudinal direction, these central axes may coincide with each other, and one You don't have to.

Further, for example, the second distance, the electric field generated in the second inner surface portion by the voltage which the power supply is applied may be a distance equal to or less than 1.6 × 10 6 ^{V /} m.

Further, for example, the value of the voltage applied between the first electrode and the second electrode may be 5 kV or less, and the second distance may be 2.6 mm or more.

Further, for example, the value of the voltage applied between the first electrode and the second electrode may be 5 kV or more, and the second distance may be 5 mm or more.

Further, for example, the first electrode may include a long columnar electrode portion having a downstream end and an upstream rear end of the gas flow. The first insulator may be a cylindrical body that surrounds the side surface of the electrode portion on the distal end side. The second insulator may be a tubular body that surrounds the side surface of the electrode portion on the rear end side. The electrode portion, the first insulator, and the second insulator may be arranged coaxially.

Further, for example, the second insulator may be a cylinder or a square cylinder.

Further, for example, the material of the first insulator may be different from the material of the second insulator.

Further, for example, the material of the first insulator may be the same as the material of the second insulator, and the first insulator may be integrally formed with the second insulator.

Hereinafter, embodiments will be specifically described with reference to the drawings.

It should be noted that all of the embodiments described below show comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, etc. shown in the following embodiments are examples, and are not intended to limit the present disclosure. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components.

Further, each figure is a schematic view and is not necessarily exactly illustrated. Therefore, for example, the scales and the like do not always match in each figure. Further, in each figure, substantially the same configuration is designated by the same reference numerals, and duplicate description will be omitted or simplified.

(Embodiment 1)
[1-1. Overview]
First, the outline of the liquid processing apparatus according to the embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the configuration of the liquid processing apparatus 1 according to the present embodiment.

As shown in FIG. 3, the liquid processing apparatus 1 generates the plasma 4 in the gas 3 supplied into the liquid 2. The gas 3 supplied into the liquid 2 exists in the liquid 2 as bubbles. The gas-liquid interface of the bubbles created by the gas 3 may be closed in the liquid 2 or may communicate with the external space.

The liquid 2 is a liquid to be processed by the liquid processing apparatus 1. The liquid 2 is, for example, tap water, water such as pure water, or an aqueous solution. The liquid processing apparatus 1 generates an active species in the liquid 2 by generating the plasma 4 in the liquid 2. Active species include, for example, hydroxyl radical (OH), hydrogen radical (H), oxygen radical (O), superoxide anion (O ₂ ⁻ ), monovalent oxygen ion (O ⁻ ) or hydrogen peroxide (H ₂ O). ₂ ) etc. are included.

Since the generated active species decomposes the substances to be decomposed contained in the liquid 2, the liquid processing apparatus 1 can sterilize the liquid 2. Alternatively, the liquid 2 containing the active species (ie, the plasma-treated liquid 2) can be used to sterilize other liquids or gases. The plasma-treated liquid 2 can be used not only for sterilization but also for various other purposes.

[1-2. Constitution]
Next, the configuration of the liquid processing apparatus 1 according to the present embodiment will be described.

As shown in FIG. 3, the liquid processing apparatus 1 includes a processing tank 10, a reaction tank 15, a piping section 20, a first electrode 30, a first holding section 35, and a second electrode 40. A second holding portion 45, an insulator 50, a gas supply pump 60, a liquid supply pump 70, and a power supply 80 are provided. Hereinafter, each component included in the liquid processing apparatus 1 will be described in detail.

[1-2-1. Processing tank]
The treatment tank 10 is a container for storing the liquid 2. The outer shape of the treatment tank 10 may be any shape such as a rectangular parallelepiped, a cylinder, or a sphere. The treatment tank 10 may be, for example, a liquid storage tank provided with an open portion, or a tray having an open upper portion.

A piping section 20 is connected to the processing tank 10. Specifically, the treatment tank 10 is connected to the reaction tank 15 via a piping section 20. A liquid supply pump 70 is connected to the piping section 20, and the liquid 2 is circulated between the processing tank 10, the reaction tank 15, and the piping section 20.

The treatment tank 10 is formed of, for example, an acid-resistant resin material. For example, the treatment tank 10 is formed of a fluororesin such as polytetrafluoroethylene, silicone rubber, polyvinyl chloride, stainless steel, ceramic, or the like.

[1-2-2. Reaction tank]
The reaction tank 15 is a tank in which the first electrode 30 and the second electrode 40 are arranged. Specifically, the first electrode 30 and the second electrode 40 are arranged so as to penetrate the side wall of the reaction tank 15. The reaction vessel 15 is filled with the liquid 2. In the reaction tank 15, plasma 4 is generated by discharging between the first electrode 30 and the second electrode 40 in the gas 3 (bubbles) supplied by the gas supply pump 60.

The outer shape of the reaction tank 15 may be any shape such as a rectangular parallelepiped, a cylinder, or a sphere. The reaction tank 15 may be, for example, a liquid storage tank provided with an open portion, or a tray having an open upper portion. Further, the reaction tank 15 may be a part of the piping section 20.

The reaction tank 15 is formed of, for example, an acid-resistant resin material. For example, the reaction vessel 15 is formed of a fluororesin such as polytetrafluoroethylene, silicone rubber, polyvinyl chloride, stainless steel, ceramic, or the like.

[1-2-3. Piping section]
The piping section 20 is a piping for forming a flow path for the liquid 2. The piping portion 20 is formed of a hollow member such as a pipe, a tube or a hose. The piping portion 20 is formed of an acid-resistant resin material or the like. For example, the piping portion 20 is formed of a fluororesin such as polytetrafluoroethylene, silicone rubber, polyvinyl chloride, stainless steel, ceramic, or the like.

In the present embodiment, the piping unit 20 connects the treatment tank 10 and the liquid supply pump 70, connects the liquid supply pump 70 and the reaction tank 15, and connects the reaction tank 15 and the treatment tank 10. .. In this way, the piping section 20 connects the processing tank 10, the liquid supply pump 70, the reaction tank 15, and the processing tank 10 in this order to form a circulation path for the liquid 2. In FIG. 3, the solid line arrow drawn along the piping portion 20 indicates the direction in which the liquid 2 flows (that is, the circulation direction).

[1-2-4. First electrode]
FIG. 4A is a cross-sectional view showing an example of the first electrode 30 according to the present embodiment. Specifically, FIG. 4A shows a cross section of the first electrode 30 that passes through the long axis. As shown in FIG. 4A, the first electrode 30 includes an electrode portion 31 and a screw portion 32.

The first electrode 30 is one of a pair of electrodes for generating plasma 4. The first electrode 30 is used as a reaction electrode, and plasma 4 is generated around it.

The electrode portion 31 is a long columnar electrode portion provided on the tip end side of the first electrode 30. The diameter of the electrode portion 31 is a diameter at which plasma 4 can be generated, and is, for example, 2 mm or less. Here, as an example, the diameter of the electrode portion 31 is 0.8 mm.

The electrode portion 31 is formed of, for example, tungsten, but is not limited thereto. The electrode portion 31 may be formed of a metal material such as aluminum, iron or copper or an alloy thereof.

At least a part of the first electrode 30 is arranged in the space 52. Specifically, at least a part of the electrode portion 31 of the first electrode 30 is arranged in the reaction vessel 15. As shown in FIG. 4A, the electrode portion 31 is surrounded by the insulator 50 via the space 52. When the gas 3 is not supplied by the gas supply pump 60, the liquid 2 fills the space 52, so that at least a part of the first electrode 30 is arranged in the liquid 2 and becomes the liquid 2. Contact. When the gas 3 is supplied by the gas supply pump 60, the supplied gas 3 fills the space 52, so that the electrode portion 31 is covered with the supplied gas 3 and does not come into contact with the liquid 2.

In the present embodiment, the electrode portion 31 and the insulator 50 are arranged coaxially. A space 52 is provided between the electrode portion 31 and the insulator 50 over the entire circumference. That is, the space 52 is a cylindrical space having a substantially uniform width d1. The width d1 is the first distance, which is the shortest distance between the side surface 36 of the first electrode 30 and the partial region 56 of the inner side surface 55 of the insulator 50, and is 1 mm or more. The width d1 may be, for example, 1 mm or more and 3 mm or less.

The screw portion 32 is a metal member that supports the electrode portion 31. Specifically, the electrode portion 31 is fixed by being press-fitted into the screw portion 32. The screw portion 32 is electrically connected to the electrode portion 31, and transmits the electric power received from the power source 80 to the electrode portion 31.

The screw portion 32 is a columnar support portion provided on the rear end side of the electrode portion 31. The diameter of the screw portion 32 is larger than the diameter of the electrode portion 31, for example, 3 mm. For example, the screw portion 32 is formed by using a metal material such as stainless steel or iron that is easy to process.

The screw portion 32 is held by the first holding portion 35. Specifically, a male screw is provided on the outer surface of the screw portion 32. The male screw is screwed with the female screw provided in the first holding portion 35, so that the screw portion 32 is held by the first holding portion 35.

The threaded portion 32 is provided with a through hole 34 connected to the gas supply pump 60. The through hole 34 communicates with the space 52. Therefore, the gas 3 supplied from the gas supply pump 60 is discharged from the opening 51 of the insulator 50 into the liquid 2 stored in the reaction tank 15 through the through hole 34 and the space 52.

In the present embodiment, as shown in FIG. 4A, the screw portion 32 is provided with two through holes 34. As a result, the pressure loss of the gas 3 in the through hole 34 is suppressed. The number of through holes 34 may be only one or three or more.

As shown in FIG. 4A, the end face (tip) 33 of the first electrode 30 recedes into the space 52 from the opening 51. The retreat amount d2 at this time is a range in which the contact between the plasma 4 generated in the vicinity of the end surface 33 of the first electrode 30 and the inner surface 55 of the insulator 50 is suppressed. Specifically, the retreat amount d2 of the end face 33 of the first electrode 30 is 0 mm or more and 3 mm or less. The retreat amount d2 may be less than 3 mm.

The retreat amount d2 can be adjusted by rotating the screw portion 32 around the axis. As the screw portion 32 rotates, the electrode portion 31 and the screw portion 32 are interlocked with each other and move in the axial direction with respect to the insulator 50 fixed to the first holding portion 35. As a result, the position of the end face 33 can be made variable. For example, as shown in FIG. 4B, the end surface 33 of the first electrode 30 may project from the opening 51 to the outside of the space 52. For example, the end face 33 projects from the opening 51 to the outside of the space 52 by 1 mm or more. Further, the end face 33 may protrude from the opening 51 to the outside of the space 52 by 3 mm or less.

FIG. 4B is a cross-sectional view showing another example of the first electrode 30 of the present embodiment. The protrusion amount d3 at this time is a range within the gas 3 supplied by the gas supply pump 60. Specifically, the protrusion amount d3 of the end face 33 of the first electrode 30 is 0 mm or more and 3 mm or less.

[1-2-5. First holding part]
The first holding portion 35 is a member for holding the first electrode 30. In the present embodiment, the first holding portion 35 holds the first electrode 30 and the insulator 50 and attaches them to a predetermined position in the reaction tank 15.

The first holding portion 35 is provided with a female screw. The female screw is screwed with the male screw of the screw portion 32 of the first electrode 30. Thereby, by rotating the screw portion 32 around the axis, the position of the first electrode 30 can be adjusted in the axial direction with respect to the first holding portion 35. Since the insulator 50 is fixed to the first holding portion 35 or the reaction tank 15, the position of the end surface 33 of the first electrode 30 with respect to the opening 51 of the insulator 50 can be adjusted. That is, the amount of retreat d2 or the amount of protrusion d3 of the end face 33 of the first electrode 30 can be adjusted.

[1-2-6. Second electrode]
FIG. 5 is a cross-sectional view showing a second electrode 40 according to the present embodiment. Specifically, FIG. 5 shows a cross section of the second electrode 40 that passes through the long axis. As shown in FIG. 5, the second electrode 40 includes an electrode portion 41 and a screw portion 42.

The second electrode 40 is the other of the pair of electrodes for generating the plasma 4. At least a part of the second electrode 40 is arranged in the liquid 2. Specifically, the electrode portion 41 of the second electrode 40 is arranged in the reaction vessel 15 and comes into contact with the liquid 2.

The electrode portion 41 is a long columnar electrode portion provided on the tip end side of the second electrode 40. The size and material of the electrode portion 41 are the same as those of the electrode portion 31 of the first electrode 30, but may be different.

The screw portion 42 is a metal member that supports the electrode portion 41. Specifically, the electrode portion 41 is fixed by being press-fitted into the screw portion 42. The screw portion 42 is electrically connected to the electrode portion 41, and transmits the electric power received from the power source 80 to the electrode portion 41.

The screw portion 42 is a columnar support portion provided on the rear end side of the second electrode 40. The diameter of the screw portion 42 is larger than the diameter of the electrode portion 41, for example, 3 mm. For example, the screw portion 42 is formed by using a metal material such as stainless steel or iron that is easy to process.

The screw portion 42 is held by the second holding portion 45. Specifically, a male screw is provided on the outer surface of the screw portion 42. The screw portion 42 is held by the second holding portion 45 by screwing the male screw with the female screw provided in the second holding portion 45.

[1-2-7. Second holding part]
The second holding portion 45 is a member for holding the second electrode 40. In the present embodiment, the second holding portion 45 holds the second electrode 40 and is attached to a predetermined position of the reaction tank 15.

The second holding portion 45 is provided with a female screw. The female screw is screwed with the male screw of the screw portion 42 of the second electrode 40. Thereby, the position of the electrode portion 41 located in the reaction tank 15 can be adjusted.

[1-2-8. Insulator (first insulator)]
The insulator 50 is an example of a tubular first insulator having an opening 51 and an inner side surface 55 for discharging the gas 3 into the liquid 2. The insulator 50 is arranged so as to surround the side surface 36 of the first electrode 30 with the space 52 interposed therebetween. The insulator 50 is a tubular insulator in which an opening 51 is provided in an end surface 53 in contact with the liquid 2. In the present embodiment, the insulator 50 is a long cylindrical body that surrounds the side surface 36 of the electrode portion 31 of the first electrode 30.

The inner diameter of the insulator 50 is larger than the outer diameter of the electrode portion 31. Further, the electrode portion 31 and the insulator 50 are arranged coaxially. Therefore, the space 52 is formed in a cylindrical shape over the entire circumference of the electrode portion 31. The space 52 is an example of the first space, and is a space surrounded by the inner side surface 55 of the insulator 50. Due to the space 52, the electrode portion 31 does not come into contact with the insulator 50. For example, the inner diameter of the insulator 50 is 3 mm, and the outer diameter of the electrode portion 31 is 0.8 mm. As a result, the width d1 of the space 52 becomes 1.1 mm.

The opening 51 of the insulator 50 is an example of a first opening for releasing the gas 3 into the liquid 2. The gas 3 supplied to the space 52 is discharged into the liquid 2 in the reaction vessel 15 through the opening 51. The released gas 3 becomes bubbles and is diffused into the liquid 2. At this time, the opening 51 has a function of determining the upper limit of the size of the bubbles.

The inner surface 55 is an example of the first inner surface, and is an inner surface of the tubular insulator 50. The inner surface 55 includes a partial region 56. The partial region 56 is an example of a first partial region in contact with the opening 51. The partial region 56 is, for example, a ring-shaped (cylindrical side surface) region at a predetermined distance (for example, within 4 mm) from the opening 51.

The insulator 50 is made of, for example, alumina ceramic. Alternatively, the insulator 50 may be composed of magnesia, zirconia, quartz, yttrium oxide, or the like.

The insulator 50 is not limited to a cylindrical body but may be a square tubular body. Further, although the insulator 50 is held by the first holding portion 35, it may be fixed to the wall surface of the reaction tank 15. Further, the gap between the insulator 50 and the first holding portion 35 or the gap between the insulator 50 and the wall surface of the reaction tank 15 may be filled with an adhesive such as an epoxy adhesive. As a result, it is possible to prevent the liquid 2 from penetrating into the insulator 50 through the gap and destabilizing the discharge.

[1-2-9. Gas supply pump]
The gas supply pump 60 is an example of a gas supply device that discharges the gas 3 into the liquid 2 through the opening 51 by supplying the gas 3 into the space 52 of the insulator 50. The gas supply pump 60 is connected to, for example, the threaded portion 32 of the first electrode 30. For example, the gas supply pump 60 takes in ambient air and supplies the gas 3 to the space 52 through the through hole 34 of the screw portion 32. The gas supply pump 60 is not limited to air, and may supply argon, helium, nitrogen gas, oxygen gas, or the like.

In the present embodiment, the flow rate of the gas 3 supplied by the gas supply pump 60 is 0.5 L / min or more. When the gas supply pump 60 supplies the gas 3, the gas 3 pushes out the liquid 2 accumulated in the space 52 from the opening 51, and the gas 3 covers the electrode portion 31. The gas 3 is discharged into the liquid 2 in the reaction vessel 15 through the opening 51.

[1-2-10. Liquid supply pump]
The liquid supply pump 70 is an example of a liquid supply device that circulates the liquid 2 between the treatment tank 10 and the reaction tank 15 via the piping section 20. In the present embodiment, the liquid supply pump 70 is arranged in the middle of the piping section 20.

[1-2-11. power supply]
The power supply 80 generates plasma 4 by applying a voltage between the first electrode 30 and the second electrode 40. Specifically, the power supply 80 applies a pulse voltage or an AC voltage between the first electrode 30 and the second electrode 40.

For example, the applied voltage is a positive high voltage pulse of 2 kV to 50 kV / cm and 1 Hz to 100 kHz. The voltage waveform may be, for example, a pulse shape, a sinusoidal half waveform, or a sinusoidal waveform. The current value flowing between the first electrode 30 and the second electrode 40 is, for example, 1 mA to 3 A. Here, as an example, the power supply 80 applies a positive pulse voltage having a frequency of 30 kHz and a peak voltage of 4 kV.

[1-3. motion]
Subsequently, the operation of the liquid processing apparatus 1 according to the present embodiment will be described.

In the liquid processing apparatus 1 according to the present embodiment, the gas supply pump 60 supplies the gas 3 while the liquid supply pump 70 circulates the liquid 2. The gas 3 supplied by the gas supply pump 60 is supplied to the space 52 through the through hole 34 of the screw portion 32. The liquid 2 that filled the space 52 before the gas 3 was supplied is discharged into the liquid 2 in the reaction vessel 15 through the opening 51. For example, the flow rate of gas 3 is 0.8 L / min. The gas 3 covers the electrode portion 31 of the first electrode 30 by filling the space 52.

Further, the power supply 80 applies a voltage between the first electrode 30 and the second electrode 40. For example, a positive pulse voltage having a frequency of 30 kHz and a peak voltage of 4 kV is applied. As a result, an electric discharge is generated in the gas 3 (bubbles) covering the first electrode 30 from the end face 33 of the first electrode 30, and the plasma 4 is generated. The active species are generated by the plasma 4, and the generated active species are incorporated into the liquid 2. Since the liquid 2 is circulating, the active species can be distributed throughout the liquid 2.

[1-4. Effect etc.]
[1-4-1. Effect of the distance (width d1) between the first electrode and the insulator on the plasma]
In the liquid processing apparatus 1 according to the present embodiment, the distance between the side surface 36 of the first electrode 30 and the inner surface surface 55 of the insulator 50 is 1 mm or more, for example, 3 mm or less.

As described above, in the liquid processing apparatus 1, the distance between the side surface 36 of the first electrode 30 and the inner surface surface 55 of the insulator 50 (that is, the width d1 of the space 52) is 1 mm or more and is separated. Therefore, dielectric barrier discharge and creeping discharge between the insulator 50 and the first electrode 30 are less likely to occur. Therefore, since the surface of the insulator 50 is less likely to be exposed to the plasma generated by these discharges, the precipitation of silica on the inner surface 55 (partial region 56) of the insulator 50 is suppressed.

FIG. 6 is a diagram showing the results of observing the first electrode 30 and the insulator 50 according to the present embodiment from the opening 51 side. Specifically, FIG. 6 shows after the power supply 80 applies a voltage between the first electrode 30 and the second electrode 40 for 1 hour using 500 cc of water having a silica concentration of 72 ppm as the liquid 2. , The result of observing the opening 51 is shown. In FIG. 6, the end face 33 of the first electrode 30 is partially photographed, and a white portion is shown near the center of the circular broken line.

In the liquid processing apparatus 1 according to the present embodiment, as shown in FIG. 6, no precipitate is observed on the inner side surface 55 near the opening 51 of the insulator 50. Even if a small amount of precipitate adheres to the inner surface 55 of the insulator 50, the instability of the discharge is unlikely to occur because the width d1 is 1 mm or more.

Further, in the liquid processing apparatus 1, the width d1 is 3 mm or less and is not too far apart. Therefore, the gas 3 supplied to the space 52 makes it easier to cover the electrode portion 31, so that the shape of the gas-liquid interface and the like become more stable, and the discharge becomes stable.

As described above, the liquid processing apparatus 1 according to the present embodiment can stably generate the plasma 4 with stable discharge.

[1-4-2. Effect of receding amount d2 on plasma]
Next, regarding the relationship between the distance (width d1) between the side surface 36 of the first electrode 30 and the inner surface 55 of the insulator 50 and the amount of retreat d2 of the end surface 33 of the first electrode 30 from the opening 51. explain.

Here, as the liquid 2, 500 cc of water having a silica concentration of 88 ppm is used, and after the power supply 80 applies a voltage between the first electrode 30 and the second electrode 40 for 1 hour, the discharge becomes unstable. It was observed whether or not to do so. The flow rate of the gas 3 supplied by the gas supply pump 60 is 1.0 L / min, the inner diameter of the insulator 50 is 3 mm, and the diameter of the electrode portion 31 of the first electrode 30 and the position of the end face 33 are changed. Observation was performed for each combination of width d1 and receding amount d2. The observed results are shown in FIG.

FIG. 7 shows the stability of the plasma 4 with respect to the distance (width d1) between the first electrode 30 and the insulator 50 according to the present embodiment and the receding amount d2 of the end face 33 of the first electrode 30. It is a figure which shows. In FIG. 7, the horizontal axis is the width d1 and the vertical axis is the receding amount d2. Further, the circles (◯) indicate that the amount of silica deposited was extremely small and the discharge was stable. The cross mark (x) indicates that silica was precipitated and the discharge was destabilized. If the light due to the discharge is blinking visually, it is judged that the discharge is unstable, and if the light due to the discharge can be continuously confirmed at a predetermined brightness, the discharge is stable. It was judged.

As shown in FIG. 7, when the width d1 was smaller than 1 mm (specifically, about 0.1 mm and 0.3 mm), the discharge was not stable regardless of the retreat amount d2. When the width d1 was 1.1 mm and the retreat amount d2 was 2 mm and 3 mm, no silica precipitation was observed and the discharge was stable.

On the other hand, as shown in FIG. 8, even if the width d1 is 1.1 mm, when the retreat amount d2 is 4 mm, silica precipitate 90x is observed and the discharge is not stable. Note that FIG. 8 is a diagram showing the results of observing the first electrode 30 and the insulator 50 from the opening 51 side when the width d1 shown in FIG. 7 is 1.1 mm and the receding amount d2 is 4 mm. ..

From the above, in the liquid processing apparatus 1 according to the present embodiment, the end surface 33 of the first electrode 30 is retracted from the opening 51 of the insulator 50 by 0 mm or more and 3 mm or less.

As a result, electric discharge is likely to occur between the end face 33 of the first electrode 30 and the gas-liquid interface, and the generation of electric discharge between the first electrode 30 and the insulator 50 can be suppressed. Therefore, since the generation of the precipitate 90x such as silica can be suppressed, the liquid processing apparatus 1 can generate the plasma 4 more stably with the discharge more stable.

As shown in FIG. 7, when the width d1 was 2.6 mm and the receding amount d2 was 3 mm, no silica precipitation was observed and the discharge was stable.

Even when the end surface 33 of the first electrode 30 protrudes from the opening 51, the plasma 4 can be stably generated. This is because most of the discharge is generated between the end face 33 and the gas-liquid interface, and the discharge between the electrode portion 31 and the inner surface 55 of the insulator 50 is suppressed.

However, when the protrusion amount d3 of the end face 33 is less than 3 mm, the gas 3 easily covers the entire electrode portion 31 including the end face 33, and the discharge becomes more stable. Therefore, when the protrusion amount d3 is 0 mm or more and 3 mm or less, the discharge is stable and the plasma 4 can be stably generated. For example, if the supply amount of the gas 3 is increased and the gas 3 can stably cover the electrode portion 31, the protrusion amount d3 may be larger than 3 mm.

[1-4-3. Effect of gas flow rate on plasma]
Next, the relationship between the retreat amount d2 and the flow rate (air flow rate) of the gas 3 supplied by the gas supply pump 60 will be described.

Here, under the same conditions as those shown in FIGS. 7 and 8, the retreat amount d2 and the air flow rate were changed, and the discharge was observed for each combination of the retreat amount d2 and the air flow rate. The observed results are shown in FIG.

FIG. 9 is a diagram showing the stability of the plasma 4 with respect to the retreat amount d2 of the end face 33 of the first electrode 30 and the air flow rate according to the present embodiment. In FIG. 9, the horizontal axis is the retreat amount d2, and the vertical axis is the air flow rate. The meanings of the circles (◯) and crosses (x) are the same as in FIG. 7. Here, the shortest distance (width d1) between the electrode portion 31 and the inner side surface 55 (partial region 56) of the insulator 50 is 1.1 mm.

As shown in FIG. 9, when the air flow rate was 0.5 L / min, silica was not deposited in the range of the retreat amount d2 of 1 mm to 3 mm, and the discharge was stable. When the retreat amount d2 was 4 mm and the air flow rate was 0.5 L / min, silica precipitation was observed and the discharge became unstable. On the other hand, even when the retreat amount d2 was 4 mm, when the air flow rate was 1.0 L / min, no silica precipitation was observed and the discharge was stabilized.

10A and 10B are diagrams showing the results of observing the first electrode 30 and the insulator 50 from the side when the retreat amount d2 shown in FIG. 9 is 4 mm. Specifically, FIG. 10A shows a case where the air flow rate is 0.3 L / min, and FIG. 10B shows a case where the air flow rate is 1.0 L / min.

In FIGS. 10A and 10B, transparent quartz was used as the material of the insulator 50 in order to facilitate observation from the side. Further, in order to make it easy to understand the positional relationship between the first electrode 30 and the space 52, the approximate shapes of the first electrode 30 and the insulator 50 are shown by white solid lines.

As can be seen by comparing FIG. 10A and FIG. 10B, the larger the air flow rate, the more the plasma 4 flows along the flow of the gas 3, so that the amount of the plasma 4 spreads toward the insulator 50 (that is, in the lateral direction). Less. By adjusting the flow rate of the gas 3 in this way, the generation region of the plasma 4 can be controlled. Specifically, the amount of exposure of the plasma 4 to the insulator 50 can be controlled by adjusting the flow rate of the gas 3.

From the above, in the liquid processing apparatus 1 according to the present embodiment, the flow rate of the gas 3 supplied by the gas supply pump 60 is 0.5 L / min or more.

As a result, as the flow rate of the gas 3 increases, the spread of the plasma 4 in the direction of the insulator 50 can be suppressed, so that the surface of the insulator 50 is less likely to be exposed to the plasma 4. Therefore, since the generation of the precipitate 90x such as silica can be suppressed, the liquid processing apparatus 1 can generate the plasma 4 more stably with the discharge more stable.

The smaller the flow rate of the gas 3, the larger the spread of the plasma 4. However, when the end face 33 of the electrode portion 31 protrudes from the opening 51, even if the plasma 4 spreads, the plasma 4 is inside the insulator 50. It hardly touches the side surface 55. Therefore, for example, when the end face 33 protrudes from the opening 51 or the retreat amount d2 is small, the flow rate of the gas 3 may be smaller than 0.5 L / min.

(Embodiment 2)
Subsequently, the second embodiment will be described. In the following second embodiment, the description will be centered on the parts different from the first embodiment, and the description of the same structure, action and effect as in the first embodiment may be omitted.

[2-1. Constitution]
FIG. 11 is a diagram showing the configuration of the liquid processing apparatus 101 according to the present embodiment. As shown in FIG. 11, the liquid treatment apparatus 101 includes a first insulator 150 and a second insulator 155 instead of the insulator 50 as compared with the liquid treatment apparatus 1 according to the first embodiment. The point is different. Further, the difference is that the first electrode 30 is attached to the upper surface of the reaction tank 15 instead of the lower surface, but the present invention is not limited to this. The first electrode 30 may be attached to the lower surface or the side surface of the reaction tank 15. The first electrode 30 of the first embodiment may also be attached to the upper surface or the side surface of the reaction tank 15.

[2-1-1. First insulator]
The first insulator 150 is substantially the same as the insulator 50 according to the first embodiment, except that the second insulator 155 is connected to the rear end side. Specifically, the first insulator 150 is a tubular insulator that surrounds only a part of the electrode portion 31 of the first electrode 30 rather than the entire electrode portion 31. For example, the first insulator 150 is a cylindrical body having an opening 151, and surrounds a side surface 36 on the tip end (front end) side of the electrode portion 31 of the first electrode 30 via a space 152.

The first insulator 150 is arranged coaxially with the electrode portion 31. The first distance D1, which is the shortest distance between the inner side surface 157 of the first insulator 150 and the side surface 36 of the first electrode 30 (specifically, the electrode portion 31), relates to the first embodiment. It is the same as the width d1 of the space 52. The first distance D1 is 1 mm or more. The first distance D1 may be, for example, 1 mm or more and 3 mm or less.

The first insulator 150 is fixed to the wall surface of the reaction tank 15, for example. The gap between the first insulator 150 and the wall surface of the reaction tank 15 may be filled with an adhesive such as an epoxy adhesive. Alternatively, the first insulator 150 may be fixed and supported by the second insulator 155. In the present embodiment, the rear end side of the first insulator 150 is connected to the tip end side of the second insulator 155.

The material, size, function, and the like of the first insulator 150 are the same as those of the insulator 50 according to the first embodiment, for example.

[2-1-2. Second insulator]
The second insulator 155 is a tubular insulator arranged so as to surround the side surface 36 of the first electrode 30 with the space 156 interposed therebetween. The second insulator 155 is connected to the side opposite to the end face on the distal end side of the first insulator 150 so that the inside of the second insulator 155 and the inside of the first insulator 150 communicate with each other. There is. Specifically, the space 152 of the first insulator 150 and the space 156 of the second insulator 155 communicate with each other.

The second insulator 155 is a tubular body that surrounds the side surface 36 on the rear end side of the electrode portion 31 of the first electrode 30. The rear end side of the electrode portion 31 is the upstream side in the direction in which the gas supplied by the gas supply pump 60 flows. The tip end side of the electrode portion 31 is the downstream side in the direction in which the gas supplied by the gas supply pump 60 flows. That is, in FIG. 11, the lower side is the front end side and the upper side is the rear end side. The second insulator 155 surrounds a portion on the rear end side of the portion of the electrode portion 31 surrounded by the first insulator 150. The second insulator 155 does not have to surround the end face on the rear end side of the electrode portion 31 or the screw portion 32.

As shown in FIG. 11, the inner surface 158 of the second insulator 155 includes a part partial region 159a, and a part component region 159b that is different from the part partial region 159a. Each part partial regions 159a及beauty section partial region 159b, surrounds the first electrode 30. In the threaded portion 32 near parts component region 159b, is narrower the distance between the side surface 36 of the first electrode 30, in other parts partial region 159a, the distance between the side surface 36 of the first electrode 30 is wider ing. The side surface 36 of the first electrode 30 and the second distance D2 is the shortest distance between the put that part partial area 159a to the inner surface 158 of the second insulator 155 is greater than the first distance D1. The second distance D2 is a distance determined according to the voltage applied between the first electrode 30 and the second electrode 40. That is, the second distance D2 is a distance determined according to the voltage applied by the power supply 80. Details will be described later.

The second insulator 155 is, for example, a cylindrical body, but is not limited to this. For example, the second insulator 155 may be a square cylinder, and has a shape (for example, a funnel shape) in which the distance between the first electrode 30 and the inner side surface 158 of the second insulator 155 changes. You may. Even when the second insulator 155 has a funnel shape, the inner side surface portion that surrounds the side surface 36 of the first electrode 30 and whose shortest distance from the side surface 36 of the first electrode 30 is larger than the first distance D1. The second insulator 155 has.

In the example of FIG. 11, the second insulator 155 is a cylindrical body in which both the front end side and the rear end side are partially closed. A circular opening having a diameter substantially matching the outer diameter of the first insulator 150 is provided on the tip end side of the second insulator 155, and the first insulator 150 is connected to the opening. .. On the rear end side of the second insulator 155, a circular opening having a diameter substantially matching the outer diameter of the screw portion 32 is provided, and the screw portion 32 is fixed to the opening. Here, the opening on the rear end side may be provided with a female screw that is screwed into the male screw of the screw portion 32.

The second insulator 155 is, for example, a flat tubular body, but is not limited to this. The second insulator 155 may be a tubular body that is long in the axial direction of the electrode portion 31. Further, the second insulator 155 may be, for example, a polygonal body such as a rectangular parallelepiped or a cube having a hollow inside.

The member constituting the second insulator 155 is not limited to a specific insulator, and for example, an acrylic resin such as PMMA (Polyphenylene sulfide), PPS (Polyphenylene sulfide), PEEK (Polyphenylene sulfide), alumina ceramic, quartz, magnesia, etc. It may be composed of zirconia or the like.

The second insulator 155 may be made of a material different from the material of the first insulator 150. Alternatively, the first insulator 150 and the second insulator 155 may be integrally made of the same material.

[2-2. Effect etc.]
Hereinafter, the effect of the present embodiment by providing the second insulator 155 on the rear end side of the first insulator 150 will be described, including the background to the present embodiment.

[2-2-1. Background to this embodiment and main features of this embodiment]
When a high voltage is applied to an electrode surrounded by a tubular insulator having an opening through a space like the first electrode 30 in the present disclosure to generate plasma, the opening of the insulator Maxwell stress is applied to the gas-liquid interface of the liquid to be treated in the vicinity according to the electric field generated there. As a result, when the discharge is continuously performed for a long time (for example, 50 minutes or more), the liquid to be treated penetrates into the inside of the insulator through the opening of the insulator along the inner side surface, and the discharge becomes unstable. there is a possibility.

On the other hand, in the liquid processing apparatus 101 according to the present embodiment, the tip end side of the side surface 36 of the first electrode 30 is surrounded by the tubular first insulator 150, and the root side of the first electrode 30 is formed. Was surrounded by a tubular second insulator 155. Further, the rear end of the first insulator 150 and the front end of the second insulator 155 were connected.

At this time, the second distance D2 between the side surface 36 of the first electrode 30 inner surface portion of the second insulator 155 (part minute region 159a), the side surface 36 of the first electrode 30 first The distance between the insulator 150 and the inner surface 157 of the insulator 150 is set to be larger than the first distance D1. As a result, the electric field generated on the inner surface 158 of the second insulator 155 becomes smaller than the electric field generated on the inner surface 157 of the first insulator 150, and is applied to the inner surface 158 of the second insulator 155. Maxwell stress is also reduced. Therefore, the liquid 2 that has infiltrated through the opening 151 of the first insulator 150 is difficult to infiltrate into the inside of the second insulator 155, and the liquid 2 is prevented from reaching the root of the first electrode 30. Can be done.

At this time, the second distance D2 is, for example, a distance determined according to the value of the voltage applied between the first electrode 30 and the second electrode 40. From the experimental results and simulation results described later, for example, when the voltage value is 5 kV or less, the second distance D2 may be set to 2.6 mm or more. When the voltage value is 5 kV or more, the second distance D2 may be set to 5.0 mm or more. As a result, the electric field is sufficiently relaxed on the inner surface 158 of the second insulator 155. As a result, a high effect of suppressing the infiltration of the liquid 2 into the inner side surface 158 of the second insulator 155 can be expected.

Similarly, in the liquid processing apparatus 1 of the first embodiment, the first distance D1 is set to a distance determined according to the value of the voltage applied between the first electrode 30 and the second electrode 40. You may. When the value of the voltage is 5 kV or less, the first distance D1 may be set to 2.6 mm or more. When the voltage value is 5 kV or more, the first distance D1 may be set to 5.0 mm or more.

Further, in the first or second embodiment, the first distance D1 or the second distance D2 may be set to 10.0 mm or less. Thereby, bubbles can be generated more appropriately.

[2-2-2. Experimental result]
In the present embodiment, a positive electrode voltage having a peak voltage of 5 kV is applied between the first electrode 30 and the second electrode 40, and plasma is generated between the first electrode 30 and the liquid 2. It was observed whether or not the liquid 2 penetrated into the inside of the first insulator 150 and the inside of the second insulator 155. At this time, tap water was used as the liquid 2.

Further, the discharge was continuously performed for 2 hours with the first distance D1 being 1.1 mm and the second distance D2 being 2.6 mm. The results of the experiment are shown in FIGS. 12 and 13.

FIG. 12 is a diagram showing the results of observing the second insulator 155 of the liquid processing apparatus 101 according to the present embodiment from the side. FIG. 13 is a diagram showing the results of observing the first insulator 150 of the liquid processing apparatus 101 according to the present embodiment from the side. Here, the first insulator 150 and the second insulator 155 are each formed of transparent quartz so that the inside can be visually recognized.

The central square region (white alternate long and short dash line) in FIG. 12 is a region surrounded by the second insulator 155, that is, a region corresponding to space 156. A black portion extending in the vertical direction in the substantially center of the space 156 indicates the electrode portion 31 of the first electrode 30. The substantially rectangular region (white alternate long and short dash line) surrounding the electrode portion 31 (not clearly shown in the figure) at the lower part of FIG. 12 is the region surrounded by the first insulator 150, that is, This is an area corresponding to the space 152. Further, the portion surrounding the electrode portion 31 in the upper part of FIG. 12 is the screw portion 32.

As can be seen from the fact that the electrode portion 31 of the space 156 is clearly visible in FIG. 12, the liquid 2 has not penetrated into the space 156. On the other hand, the tip end side of the electrode portion 31 surrounded by the first insulator 150 cannot be clearly seen, and it can be seen that the liquid 2 has infiltrated.

A rectangular region (cylindrical portion, white alternate long and short dash line) extending in the vertical direction in the center of FIG. 13 indicates the first insulator 150. The black portion extending in the vertical direction along the center of the first insulator 150 is the electrode portion 31 of the first electrode 30. The white region extending downward from the lower end of the electrode portion 31 is the plasma 4 generated by the electric discharge. The black ring-shaped portion extending in the left-right direction in the center of FIG. 13 is another member that supports the first insulator 150.

Similar to FIG. 12, since it is difficult for the electrode portion 31 to be clearly visible in the first insulator 150, the liquid 2 is inside the first insulator 150 (space 152, white alternate long and short dash line). You can see that it is invading. Further, although it is difficult to confirm from FIG. 13, it was confirmed that water droplets adhered along the inner side surface 157 of the first insulator 150.

As described above, by making the second distance D2 larger than the first distance D1, the liquid 2 that has penetrated into the first insulator 150 does not penetrate into the second insulator 155. I understand. That is, it was confirmed that the infiltration of the liquid 2 into the root of the electrode portion 31 could be suppressed by providing the second insulator 155.

Further, a discharge experiment was carried out continuously for 2 hours in each of the three cases where the first distance D1 was 2.6 mm and the second distance D2 was 4.6 mm, 7.1 mm and 9.6 mm. In these cases, no infiltration of the liquid 2 into the inside of the first insulator 150 and the second insulator 155 was observed. From this result, in an environment where the first distance D1 and the second distance D2 are 2.6 mm or more, the electric field is sufficiently relaxed on the inner side surface 158 of the first insulator 150 and the second insulator 155. I understand.

[2-2-3. simulation result]
Here, the simulation result regarding the relationship between the applied voltage and the second distance D2 will be described. Specifically, when a voltage of 5 kV is applied between the first electrode 30 and the second electrode 40 and the second distance D2 is 2.6 mm, the inner surface of the second insulator 155 When calculated by simulating the electric field generated 158 was 1.6 × ¹⁰ 6 V / m. As the value of the electric field is small, since the smaller the value of the Maxwell stress, at least, in an environment where electric field of less than 1.6 × 10 6 ^{V /} m occurs, penetration of the liquid 2 to the inside of the second insulator 155 is observed It is thought that it will not be done.

FIG. 14 shows the relationship between the second distance D2 between the first electrode 30 and the second insulator 155 according to the present embodiment and the electric field value generated on the inner surface 158 of the second insulator 155. It is a figure which shows the result of simulating. Specifically, FIG. 14 shows the static electric field simulation results for each of the three cases where the applied voltage between the first electrode 30 and the second electrode 40 is 2.5 kV, 5 kV, and 10 kV. .. Further, each plot shows the case where the second distance D2 is 1.1 mm, 2.6 mm, 4.9 mm, 7.1 mm, and 9.6 mm.

The simulation result shown in FIG. 14 shows how the absolute value of the electric field generated on the inner surface 158 of the second insulator 155 changes according to the second distance D2. The broken line in FIG. 14, based on the experimental results described above, the liquid 2 is a second inside surface 158 of the insulator 155 represents the penetration was not a possible electric field threshold ^{(1.6 × 10 6 V / m} ) ing. If it is below the broken line, it is possible to suppress the infiltration of the liquid 2 into the inside of the second insulator 155.

From the simulation results shown in FIG. 14, by setting the second distance D2 to 5 mm or more, the magnitude of the electric field generated on the inner surface 158 of the second insulator 155 even in an environment where the applied voltage is 10 kV or less. Can be 1.6 × 10 ⁶ V / m or less. That is, it is possible to suppress the infiltration of the liquid 2 into the inside of the second insulator 155.

When the applied voltage is 5 kV or less and not large, the magnitude of the electric field generated on the inner side surface 158 of the second insulator 155 is 1.6 by setting the second distance D2 to 2.6 mm or more. × 10 ^{It can be 6} V / m or less.

As described above, according to the present embodiment, the second distance D2 is set according to the value of the voltage applied between the first electrode 30 and the second electrode 40, so that the second distance D2 can be set. The electric field generated on the inner side surface 158 of the insulator 155 can be sufficiently relaxed. As a result, it is possible to prevent the liquid 2 from entering the inside of the second insulator 155, so that stable plasma generation is possible.

(Embodiment 3)
Subsequently, the third embodiment will be described. In the following embodiment 3, the description will be focused on the portion different from that of the first embodiment, and the description of the same structure, action and effect as that of the first embodiment may be omitted.

[3-1. Constitution]
FIG. 15 is a diagram showing the configuration of the liquid processing apparatus 201 according to the present embodiment. As shown in FIG. 15, the liquid processing apparatus 201 has a first electrode 230 and a first electrode 230 instead of the first electrode 30 and the first holding portion 35 as compared with the liquid processing apparatus 1 according to the first embodiment. The difference is that the first holding portion 235 is provided.

FIG. 16 is a cross-sectional view showing the first electrode 230 and the insulator 50 according to the present embodiment. FIG. 17 is a front view of the first electrode 230 and the insulator 50 according to the present embodiment when viewed from the tip side. Note that FIG. 17 does not show the first holding portion 235. Further, in FIG. 17, in order to make the schematic shape of each member easy to understand, the same shading as that attached to each member in FIG. 16 is attached to each member.

[3-1-1. First electrode]
As shown in FIGS. 16 and 17, the first electrode 230 includes an electrode portion 231 and a screw portion 232. The first electrode 230 is one of a pair of electrodes for generating plasma 4. The first electrode 230 is used as a reaction electrode, and plasma 4 is generated around it.

The electrode portion 231 is a long columnar electrode portion provided on the tip end side of the first electrode 230. The axial length of the electrode portion 231 is, for example, the same as the axial length of the insulator 50, or longer than the axial length of the insulator 50. The rear end of the electrode portion 231 projects from the opening 54 on the rear end side of the insulator 50 when the end surface 233 on the front end side is arranged so as to retract from the opening 51 of the insulator 50. The opening 54 is an example of a second opening on the opposite side of the opening 51. For example, the length of the electrode portion 231 is 15 mm or more and 30 mm or less, but is not limited to this.

The screw portion 232 is an example of a support portion for supporting the electrode portion 231 provided on the rear end side of the electrode portion 231. The screw portion 232 is a columnar portion thicker than the electrode portion 231. As shown in FIG. 17, the screw portion 232 is provided with a gas supply hole 234.

The gas supply hole 234 is a hole through which the gas 3 supplied by the gas supply pump 60 passes. The gas supply hole 234 is, for example, a through hole that penetrates the threaded portion 232 in the axial direction. In the present embodiment, the opening width of the gas supply hole 234 and the inner diameter of the insulator 50 are substantially the same.

Specifically, as shown in FIG. 17, the gas supply hole 234 has a cross-shaped front view. The electrode portion 231 is press-fitted into the center of the cross-shaped gas supply hole 234. As a result, the screw portion 232 supports the electrode portion 231. The gas supply holes 234 are formed radially around the electrode portion 231 in the front view. Specifically, the gas supply hole 234 is formed with two through holes 234a and 234b. Each of the two through holes 234a and 234b has a long rectangular opening in the radial direction of the threaded portion 232 and is orthogonal to the center of the threaded portion 232 in the front view. The length of each rectangular opening of the through holes 234a and 234b matches the inner diameter of the insulator 50. The length of the rectangular opening is, for example, the length along the radial direction of the screw portion 232 and the opening width of the gas supply hole 234. The width of the rectangular opening is, for example, shorter than the diameter of the electrode portion 231.

The shape of the gas supply hole 234 is not limited to the illustrated example. For example, the gas supply hole 234 may be only one of only one through hole 234a and 234b, or may be a combination of three or more through holes.

[3-1-2. First holding part]
The first holding portion 235 is a member for holding the first electrode 230. In the present embodiment, the first holding portion 235 holds the first electrode 230 and the insulator 50 and attaches them to a predetermined position in the reaction vessel 15.

The first holding portion 235 holds the screw portion 232 as shown in FIG. Specifically, a female screw (not shown) is provided on the inner surface of the first holding portion 235, and is screwed into a male screw (not shown) provided on the outer surface of the screw portion 232.

The first holding portion 235 is a tubular body having an inner diameter substantially the same as the inner diameter of the insulator 50. Specifically, as shown in FIG. 16, the first holding portion 235 has a space 236 that communicates with the gas supply hole 234 and the space 52 of the insulator 50. The inner diameter of the space 236 and the inner diameter of the space 52 are substantially the same. The space 236 is a part of the flow path through which the gas 3 supplied from the gas supply pump 60 flows. The space 236 stabilizes the flow of the gas 3 discharged from the gas supply hole 234 and introduces the space 236 into the space 52 of the insulator 50. The axial length of the space 236 is not particularly limited, but the longer the space 236, the more stable the flow of the gas 3 can be.

[3-2. Effect etc.]
Hereinafter, the effect of the present embodiment by making the opening width of the gas supply hole 234 substantially the same as the inner diameter of the insulator 50 will be described, including the background to the present embodiment.

[3-2-1. Background to this embodiment]
As in the present disclosure, when the distance between the side surface 36 of the electrode portion 31 and the inner side surface 55 of the insulator 50 (width d1 of the space 52) is increased, that is, when the inner diameter of the insulator 50 is increased, the insulator 50 The size of the gas supply hole that introduces the airflow to the inside of the insulator 50 may be smaller than the inner diameter of the insulator 50. At this time, the flow path width of the gas 3 supplied from the gas supply hole changes discontinuously at the connection portion between the gas supply hole and the insulator 50. Due to the discontinuous change in the flow path width of the gas 3, a swirling flow of the gas 3 is generated near the inner surface 55 of the insulator 50, and the liquid 2 caught in the swirling flow is the inner side surface 55 of the insulator 50. There is a possibility of infiltrating into the inside of the insulator 50 through the above.

For example, FIG. 18 is a diagram showing a result of simulating (numerical calculation) the position of the gas-liquid interface in the vicinity of the insulator 50 according to the comparative example of the present embodiment. FIG. 19 is a diagram showing a flow velocity distribution of gas 3 in the same simulation as in FIG. In addition, in FIGS. 18 and 19, in order to make the explanation easy to understand, the screw portion 232x and the insulator 50 are shown as having no thickness. The same applies to FIGS. 20 and 21 described later.

Here, the opening width of the gas supply hole 234x is 0.8 mm, the inner diameter of the insulator 50 is 3.0 mm, the flow rate of the gas 3 supplied from the gas supply hole 234x is 1.5 L / min, and the liquid 2 (tap water). The numerical calculation is performed assuming that the flow rate circulating in the reaction vessel is 1.0 [L / min].

As shown in FIGS. 18 and 19, it can be seen that a swirling flow is generated in the vicinity of the inner surface 55 of the insulator 50. Further, it can be seen that the gas-liquid interface enters inward through the opening 51 of the insulator 50 in response to the generation of this swirling flow.

[3-2-2. Main features of this embodiment]
On the other hand, in the liquid processing apparatus 201 according to the present embodiment, as shown in FIGS. 16 and 17, the opening width of the gas supply hole 234 and the inner diameter of the insulator 50 are substantially the same, so that the insulation is insulated. The flow velocity distribution of the gas 3 supplied to the inside of the body 50 is stable, and the shape of the bubbles formed at the opening 51 of the insulator 50 is stable.

FIG. 20 is a diagram showing a result of simulating (numerical calculation) the position of the gas-liquid interface in the vicinity of the insulator 50 according to the present embodiment. FIG. 21 is a diagram showing a flow velocity distribution of gas 3 in the same simulation as in FIG.

At this time, the opening width of the gas supply hole 234 is 3.0 mm, the inner diameter of the insulator 50 is 3.0 mm, the flow rate of the gas 3 supplied from the gas supply hole 234 is 1.5 L / min, and the liquid 2 is the reaction tank 15. Numerical calculation is performed assuming that the flow rate circulating in the inside is 1.0 L / min.

As shown in FIGS. 20 and 21, it can be seen that the flow velocity distribution of the gas 3 generated inside the insulator 50 is a uniform distribution. As a result, as shown in FIG. 20, it can be seen that the gas-liquid interface is located in the vicinity of the opening 51 of the insulator 50 and hardly penetrates into the inside of the insulator 50.

As described above, in the liquid processing apparatus 201 according to the present embodiment, since the uniform flow velocity distribution of the gas 3 is generated inside the insulator 50, the liquid 2 is not drawn into the inside of the insulator 50. Therefore, stable plasma generation is possible.

In this embodiment, the screw portion 232 may be inserted inside the insulator 50. That is, the gas 3 that has passed through the gas supply hole 234 without providing the space 236 is directly introduced into the space 52 of the insulator 50 without passing through the space 236.

[3-3. Modification example]
Subsequently, a modified example capable of suppressing the generation of a swirling flow inside the insulator 50 will be described with reference to FIG. 22. FIG. 22 is a cross-sectional view showing the vicinity of the first electrode 230 and the insulator 50 of the liquid processing apparatus according to the present modification.

As shown in FIG. 22, the liquid processing apparatus according to the present modification includes a bottomed tubular body portion 332 and an introduction port 335 instead of the threaded portion 232 of the first electrode 230. The introduction port 335 is, for example, an opening of a pipe connecting the gas supply pump 60 and the bottomed tubular body portion 332.

The bottomed tubular body portion 332 is a tubular body having an opening 334 which is an example of a third opening and a closed end portion opposite to the opening 334. The bottomed tubular body portion 332 is a bottomed tubular body-shaped member having substantially the same opening width as the insulator 50. For example, the bottomed cylindrical body portion 332 is a bottomed cylindrical body having a space 333 and a circular opening 334. The bottomed tubular body portion 332 functions as a flow path changing portion for changing the traveling direction of the gas 3 supplied by the gas supply pump 60 in the space 333 and stably supplying the gas 3 to the inside of the insulator 50.

The bottomed tubular body portion 332 is provided on the rear end side of the insulator 50. Specifically, the bottomed tubular body portion 332 is connected to the rear end side of the insulator 50 so as to be located coaxially with the insulator 50. The space 333 of the bottomed tubular body portion 332 and the space 52 of the insulator 50 communicate with each other. The space 333 and the space 52 form a flow path for the gas 3.

For example, as shown in FIG. 22, the opening 334 of the bottomed tubular body portion 332 is connected to the opening 54 on the rear end side of the insulator 50. The opening 54 and the opening 334 have the same shape and the same size. That is, the bottomed tubular body portion 332 and the insulator 50 are connected so that the flow path width is substantially uniform.

The material constituting the bottomed tubular body portion 332 is, for example, an insulator. Specifically, the bottomed tubular body portion 332 may be made of, for example, an acrylic resin such as PMMA (Polyphenylene sulfide), PPS (Polyphenylene sulfide), PEEK (Polyetheretherketone), alumina ceramic, quartz, magnesia, zirconia or the like. Good.

The introduction port 335 is an opening for introducing the gas 3 supplied by the gas supply pump 60 into the insulator 50. The introduction port 335 is not orthogonal to the axial direction of the insulator 50. Specifically, the introduction port 335 is provided on the side wall of the bottomed tubular body portion 332 and is substantially parallel to the axial direction of the insulator 50. In other words, the inflow direction of the gas 3 when passing through the introduction port 335 (that is, the direction orthogonal to the introduction port 335) is substantially orthogonal to the axial direction. The introduction port 335 may be inclined with respect to the axial direction of the insulator 50. That is, the inflow direction of the gas 3 when passing through the introduction port 335 may intersect the axial direction of the insulator 50.

The gas 3 supplied into the bottomed tubular body portion 332 through the introduction port 335 travels toward the insulator 50 in the space 333 of the bottomed tubular body portion 332 with its traveling direction changed. Since the opening 334 of the bottomed tubular body portion 332 and the opening 54 on the rear end side of the insulator 50 have the same shape and the same size, the gas 3 is insulated without the flow path width changing discontinuously. It travels inside the body 50 (space 52) along the axial direction and is discharged into the liquid 2 through the opening 51.

As described above, since there is no discontinuous change in the flow path width of the gas 3 inside the insulator 50, a uniform flow velocity distribution of the gas 3 can be generated inside the insulator 50. Therefore, since the generation of the swirling flow is suppressed inside the insulator 50, the infiltration of the liquid 2 can be suppressed. As a result, according to the liquid processing apparatus according to the present modification, more stable plasma can be generated.

In this modified example, the introduction port 335 is provided on the side wall of the bottomed tubular body portion 332 provided on the rear end side of the insulator 50, but the present invention is not limited to this. The introduction port 335 may be provided so as to penetrate the side wall of the insulator 50. That is, the insulator 50 may have a bottomed tubular shape in which the opening 54 on the rear end side is closed, and the introduction port 335 may be provided on the side wall in the vicinity of the opening 54. As a result, the number of parts can be reduced, and the weight and cost of the liquid processing apparatus can be reduced.

Further, in this modification, the insulator 50 and the bottomed tubular portion 332 are directly connected to each other, but similarly to the configuration shown in FIG. 16, between the insulator 50 and the bottomed tubular portion 332, A first holding portion 235 having a space 236 may be provided. In this case, the spaces 333, 236, and 52 have substantially the same diameter, and the flow path width of the gas 3 can be made substantially constant.

(Other embodiments)
Although the liquid processing apparatus according to one or more embodiments has been described above based on the embodiments, the present disclosure is not limited to these embodiments. As long as the gist of the present disclosure is not deviated, various modifications that can be conceived by those skilled in the art are applied to the present embodiment, and a form constructed by combining components in different embodiments is also included in the scope of the present disclosure. Is done.

For example, in the above embodiment, the case where the position of the end face 33 of the electrode portion 31 is variable by rotating the screw portion 32 has been described, but the present invention is not limited to this. The positional relationship between the electrode portion 31 and the insulator 50 may be fixed. Specifically, the first holding portion 35 may not be provided with a female screw, and the screw portion 32 may not be provided with a male screw.

Further, for example, although the first electrode 30 includes an electrode portion 31 and a screw portion 32, the first electrode 30 may be a single rod-shaped electrode (cylindrical body). Alternatively, the first electrode 30 may be a prismatic or flat electrode. The same applies to the second electrode 40.

Further, the liquid processing apparatus 1 does not include at least one of the first holding portion 35 and the second holding portion 45, and at least one of the first electrode 30 and the second electrode 40 is directly fixed to the reaction tank 15. You may.

Further, for example, in the above embodiment, the processing tank 10 and the reaction tank 15 are connected via the piping section 20, and the liquid 2 is circulated by the liquid supply pump 70, but the present invention is not limited to this. For example, the liquid processing apparatus 1 may generate the plasma 4 in the non-flowing liquid 2 (for example, still water) without providing the processing tank 10 and the piping portion 20.

Further, for example, in the above embodiment, an example in which tap water containing silica is used as the liquid 2 has been shown, but the present invention is not limited to this. The liquid 2 may be pure water or a liquid containing a mineral component such as calcium.

Further, for example, in the second embodiment described above, an example is shown in which the insulator surrounding the first electrode 30 is composed of the first insulator 150 and the second insulator 155, but the present invention is not limited to this. .. The insulator surrounding the first electrode 30 may be composed of only the first insulator 150 (corresponding to the first embodiment).

Alternatively, the insulator surrounding the first electrode 30 may be composed of only the second insulator 155. In this case, the second insulator 155 corresponds to a tubular first insulator having a first opening for releasing gas into the liquid to be treated and a first inner side surface.

Further, for example, the insulator surrounding the first electrode 30 may be one insulator in which the first insulator 150 and the second insulator 155 are integrally formed. In one insulator, a region in which the shortest distance between the inner surface thereof and the first electrode 30 is different may be provided. That is, on the inner surface of one insulator, between a first partial region where the shortest distance between the side surface of the first electrode 30 is the first distance and the side surface of the first electrode 30. A second subregion in which the shortest distance is the second distance may be included.

In addition, each of the above embodiments can be modified, replaced, added, omitted, etc. within the scope of claims or the equivalent scope thereof.

The present disclosure can be used as a liquid processing device capable of stably generating plasma, and can be used, for example, in a sterilization device, a purification device, and the like.

1, 101, 201 Liquid processing device 2 Liquid 3 Gas 4 Plasma 10 Processing tank 15 Reaction tank 20 Piping section 30, 30x, 230 First electrode 31, 41, 231 Electrode section 32, 42, 232, 232x Threaded section 33, 53, 233 End face 34, 234a, 234b Through hole 35, 235 First holding part 36 Side surface 40 Second electrode 45 Second holding part 50, 50x Insulator 51, 54, 151, 334 Opening 52, 52x, 152 , 156,236,333 space 55,157,158 inner surface 56 partial region 60 the gas supply pump 70 the liquid supply pump 80 power 90x deposit 150 first insulator 155 second insulator 159a, 159b portions partial regions 234, 234 x Gas supply hole 332 Bottomed cylinder part 335 Introduction port

Claims (21)

A tubular first insulator having a first opening and a first inner surface for releasing gas into the liquid to be treated,
With the first electrode, which is at least partially arranged in the first space surrounded by the first inner surface,
With the second electrode, which is at least partially disposed in the liquid to be treated,
A gas supply device that discharges the gas into the liquid to be treated through the first opening by supplying the gas into the first space.
A power source for generating plasma by applying a voltage between the first electrode and the second electrode is provided.
The first inner surface comprises a ring-shaped first partial region at a predetermined distance from the first opening.
The tip of the first electrode protrudes from the first opening to the outside of the first space, or recedes from the first opening into the first space by less than 3 mm.
The first distance, which is the shortest distance between the side surface of the first electrode and the first partial region, is 1 mm or more.
Liquid processing equipment. The tip of the first electrode projects out of the first space from the first opening.
The liquid processing apparatus according to claim 1. The tip of the first electrode projects 1 mm or more from the first opening to the outside of the first space.
The liquid processing apparatus according to claim 2. The tip of the first electrode projects from the first opening to the outside of the first space by 3 mm or less.
The liquid processing apparatus according to claim 2 or 3. The first inner surface is a partial region located at a position farther from the first opening than the first partial region, and includes a second partial region surrounding the first electrode.
The shortest distance, the first partial region and the second partial region when the voltage is applied between the first distance or the side surface and the second partial region of the first electrode, Is the distance at which the electric field generated in is 1.6 × 10 ⁶ V / m or less.
The liquid processing apparatus according to any one of claims 1 to 4. The first inner surface is a partial region located at a position farther from the first opening than the first partial region, and includes a second partial region surrounding the first electrode.
The shortest distance between the first distance or the side surface of the first electrode and the second partial region is 2.6 mm or more.
The liquid processing apparatus according to any one of claims 1 to 5. The shortest distance between the first distance or the side surface of the first electrode and the second partial region is 5 mm or more.
The liquid processing apparatus according to claim 6. The first distance is 1 mm or more and 3 mm or less.
The liquid processing apparatus according to any one of claims 1 to 5. The flow rate of the gas supplied by the gas supply device is 0.5 L / min or more.
The liquid processing apparatus according to any one of claims 1 to 8. The first electrode includes a long columnar electrode portion and has a long columnar electrode portion.
The first insulator is a long cylinder that surrounds the side surface of the electrode portion.
The electrode portion and the first insulator are arranged coaxially.
The liquid processing apparatus according to any one of claims 1 to 9. The first electrode is
A long columnar electrode portion having a downstream end and an upstream rear end of the gas flow,
A support portion provided on the rear end side of the electrode portion to support the electrode portion, and provided with a columnar support portion thicker than the electrode portion.
The first insulator is a cylindrical body and has a cylindrical body.
The support portion is provided with a gas supply hole through which the gas supplied by the gas supply device passes.
The opening width of the gas supply hole and the inner diameter of the first insulator are substantially the same.
The liquid processing apparatus according to any one of claims 1 to 9. Further comprising a tube having an inlet for introducing the gas supplied by the gas supply device into the first space.
The inflow direction of the gas when passing through the introduction port intersects the axial direction of the first insulator.
The liquid processing apparatus according to any one of claims 1 to 9. Further comprising a cylinder having a third opening and a closed end opposite the third opening.
The first insulator has a second opening on the opposite side of the first opening.
The opening width of the third opening is substantially the same as the opening width of the second opening.
The third opening and the second opening are connected so that the cylinder is located coaxially with the first insulator.
The introduction port is provided on the side wall of the cylinder.
The liquid processing apparatus according to claim 12. Further comprising a tubular second insulator having a second inner side surface portion surrounding the side surface of the first electrode via a second space.
The first insulator has a second opening on the opposite side of the first opening.
The second insulator is connected to the second opening side of the first insulator so that the second space and the first space communicate with each other.
The second distance, which is the shortest distance between the side surface of the first electrode and the second inner side surface portion, is larger than the first distance.
The liquid processing apparatus according to any one of claims 1 to 12. The second distance is the distance the electric field generated in the second inner surface portions when the power is applied the previous SL voltage becomes less than 1.6 × 10 6 ^{V /} m,
The liquid processing apparatus according to claim 14. The value of the voltage applied between the first electrode and the second electrode is 5 kV or less.
The second distance is 2.6 mm or more.
The liquid processing apparatus according to claim 14 or 15. The value of the voltage applied between the first electrode and the second electrode is 5 kV or more.
The second distance is 5mm or more,
The liquid processing apparatus according to claim 14 or 15. The first electrode comprises a long columnar electrode portion having a downstream end and an upstream rear end of the gas flow.
The first insulator is a cylindrical body that surrounds the side surface of the electrode portion on the distal end side.
The second insulator is a tubular body that surrounds the side surface of the electrode portion on the rear end side.
The electrode portion, the first insulator, and the second insulator are arranged coaxially.
The liquid processing apparatus according to any one of claims 14 to 17. The second insulator is a cylinder or a square cylinder.
The liquid processing apparatus according to claim 18. The material of the first insulator is different from the material of the second insulator.
The liquid processing apparatus according to any one of claims 14 to 19. The material of the first insulator is the same as the material of the second insulator, and the first insulator is integrally formed with the second insulator.
The liquid processing apparatus according to any one of claims 14 to 20.