JP2012152712A - Submerged plasma generating device and electrode device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a submerged plasma generating device for efficiently generating plasma by electric discharge in the liquid to be processed even when using at a large scale treatment facility as seen in a waste liquid treatment field site.SOLUTION: The submerged plasma generating device, which generates plasma in the liquid, includes: a main pipe (10); an air supply pipe (102) for supplying a gas to the main pipe (10); a closed body (12) closing an opening part of the main pipe (10) and formed with porous materials for discharging a gas passed through the main pipe (10) into the liquid as microbubbles; and a wire electrode (20) whose tip end part (22) is located in a space (120) formed by the main pipe (10) and the closed body (12) and provided close to the closed body (12).

Description

  The present invention relates to an in-liquid plasma generator for generating plasma in a liquid and an electrode device used therefor. More specifically, the present invention relates to an apparatus capable of generating a plasma by generating a pulse discharge in a liquid and efficiently dispersing OH radicals, ozone, and the like generated by the generation of the plasma in the liquid to be processed.

  Generate pulse discharge in water to generate OH radicals and ozone, and use this to reduce the volume of activated sludge, deodorize organic wastewater that emits a strange odor, and treat waste liquid containing discharged chemicals, etc. Has already been implemented.

  As an underwater discharge plasma apparatus that causes pulse discharge in water, there is an apparatus described in Patent Document 1 below. In this apparatus, a high voltage electrode is attached to the inside of the porous dielectric pipe, a gas passage is formed inside the porous dielectric pipe and the high voltage electrode, and the outside of the porous dielectric pipe is enclosed. By forming a water passage to be treated between the ground electrodes and connecting a high-voltage high-frequency power source or a high-voltage pulse power source to both electrodes, an underwater discharge plasma is generated in fine bubbles that have passed through the porous dielectric pipe, As a result, high concentration OH radicals and ozone can be obtained efficiently, and elution of the metal electrode is prevented.

  In the electrode described in Patent Document 1, a gas passage is formed inside the porous dielectric pipe and the high-voltage electrode as described above, and should be processed between the outside of the porous dielectric pipe and the surrounding ground electrode. Adopting a structure with a water passage, air, argon, oxygen gas, etc. are supplied to the water in the form of fine bubbles, and supplied to the inside of the porous dielectric pipe and the high voltage electrode through the gas inlet It has become.

JP 2004-268003 A

  However, the gas supplied to the water is supplied to the inside of the porous dielectric pipe and the high voltage electrode through the gas inlet while floating in the water, and the laboratory as shown in FIG. Even if the gas supply is sufficient in the case of a small-scale device, the gas supplied to the waste liquid floats in the water at a large treatment facility such as the waste liquid treatment site. It is difficult to supply the high voltage electrode efficiently and stably, which is not practical.

  In addition, since the waste liquid to be treated needs to pass through a water passage formed between the outside of the porous dielectric pipe and the surrounding ground electrode, a pump for sending the waste liquid to the water passage is necessary. The installation location is also limited to the vicinity of the discharge port of the waste liquid discharged from the pump.

  Furthermore, in order to perform waste liquid treatment efficiently, it is necessary to efficiently disperse OH radicals and ozone generated by the occurrence of underwater discharge plasma in the waste liquid, but the discharge port of the apparatus discharges only in one direction. Therefore, it is impossible to efficiently disperse OH radicals, ozone, and the like generated in the electrode or in the vicinity of the electrode over a wide area.

The inventor does not supply the gas supplied into the liquid to be processed to the water passage, but isolates the electrode from the liquid to be processed with a porous material, and ejects the gas from the porous material into the water to form fine bubbles. By generating a plasma by generating a pulse discharge by applying a pulse voltage to the electrode isolated in the generated fine bubbles, OH radicals, ozone, etc. generated by the generation of the plasma are treated together with the fine bubbles It was found that it was efficiently dispersed in the liquid.
The present invention has been completed based on this finding.

(Object of the present invention)
Therefore, an object of the present invention is to efficiently generate plasma due to discharge in a liquid to be processed even when used in a large processing facility such as a waste liquid processing site.
Another object of the present invention is to efficiently disperse OH radicals, ozone and the like generated by the generation of plasma in the liquid to be treated.

Means taken by the present invention to solve the above-mentioned problems are as follows.
The present invention
A submerged plasma generator for arranging a positive electrode and a negative electrode in a liquid and applying a voltage to the positive electrode to generate a plasma in the liquid,
A fine bubble generating means for generating fine bubbles by directly supplying gas into the liquid from the outside is provided, and either one or both of the positive electrode and the negative electrode are arranged in an isolation element having a gas passage element. And separating the liquid from the liquid, and the separation element constitutes a fine bubble generating means, and a voltage is applied to the positive electrode while discharging the gas from the separation element into the liquid and generating the fine bubbles in the liquid. It is an in-liquid plasma generator that generates plasma in it.

The present invention
An electrode device for plasma in liquid that generates plasma in liquid,
The main
An air supply element for sending gas to the main pipe;
A porous closing element that closes the opening of the main pipe and discharges the gas that has passed through the main pipe as fine bubbles in the liquid;
A wire electrode located in a space formed by the main tube and the porous closure element, provided close to the porous closure element;
A submerged plasma generating electrode device.

  As the electrode of the device according to the present invention, a wire electrode using tungsten is preferable. Wire electrodes (including needles and rods) have a small electrode surface area, electric field concentration occurs, and the amount of electrode damage is small, so that plasma can be generated at a low voltage.

As a power source of the device according to the present invention, a commercial power source (AC 100 V), an in-vehicle power source (DC 24 V), and a power source from a solar power generation device can be used.
As a gas for forming fine bubbles, oxygen, an oxygen gas, or a mixed gas of other gas such as oxygen and argon can be used.

(Function)
The negative electrode (30) is placed in the liquid to be treated, and the tip of the main pipe (10) is submerged in the liquid to be treated, so that the tip of the wire electrode (20), which is a positive electrode, and the negative electrode (30) Make them face each other.
Gas is sent directly from the outside into the liquid to be treated, and bubbles are generated in the liquid to be treated. That is, gas is sent from the outside to the main pipe (10) through the air supply pipe (102), and fine bubbles are discharged into the liquid to be treated from the porous closing element (12) at the lower end of the main pipe (10).

After the lower end of the main pipe (10) is surrounded by the released fine bubbles, when a pulse voltage is applied to the wire electrode (20), an arc discharge occurs between the tip of the wire electrode (20) and the negative electrode (30). It is generated and plasma is generated to generate OH radicals and ozone.
Immediately after the pulse voltage is applied, a high voltage is suddenly applied between the electrodes (20, 30). Thereafter, a rapid decrease in voltage occurs, and plasma is generated along with arc discharge while the pulse voltage is applied.

  The generated OH radicals and ozone are diffused in the liquid to be processed together with the released fine bubbles, thereby processing the liquid to be processed.

  According to the present invention, since the apparatus itself is provided with the fine bubble generating means, the apparatus itself and the fine bubble generating means can be installed integrally. Therefore, even when used in a large treatment facility such as a waste liquid treatment site, the underwater discharge plasma can be efficiently generated without being limited to the installation location.

  Further, the generated OH radicals, ozone, and the like expand the volume of the gas phase region due to the discharge pressure of the fine bubbles, and are efficiently diffused into the liquid to be treated together with the fine bubbles.

It is a schematic explanatory drawing which shows the whole electrode apparatus and use condition. It is the partial schematic explanatory drawing which expanded the front end side of the electrode apparatus. It is the partial schematic explanatory drawing which expanded the base side of the electrode device. It is the block diagram which showed one Embodiment of the apparatus which sends the pulse voltage as an applied voltage.

  The present invention will be described in detail based on the embodiments shown in the drawings.

Embodiment
The in-liquid plasma generator includes a main pipe 10. The base side of the main pipe 10 is bifurcated. The first branch portion is an air supply pipe 102 that is an air supply element that sends gas to the main pipe 10. The second branch portion is an electrode side tube 104 that passes the wire electrode 20 through the main tube 10.
The main tube 10 uses a glass tube that transmits visible light and has high corrosion resistance.

A funnel-shaped divergent portion 11 is formed at the tip of the main tube 10, and a porous closing body 12, which is a porous closing element, is provided at the lower end of the divergent portion 11.
The closed body 12 has an outer shape formed in a hemispherical shape and has a hemispherical hollow portion 120 therein. The closing body 12 is made of a porous ceramic. Specifically, it is mainly composed of alumina, the particle size conforms to JIS No. 2, and the diameter of the micropores is about 40 to 50 μm. It is also possible to adopt a porous material having a nanopore diameter of nano level.

The closing body 12 discharges the gas that has passed through the main pipe 10 from the fine holes into the liquid as fine bubbles.
The closing body 12 is not limited to the above material as long as it is made of an inorganic porous material such as ceramic or glass and can pass a gas such as air. Moreover, as the closing body 12, you may employ | adopt what formed many pores in the non-breathing material instead of what is called a porous material, for example.

  In the hollow portion 120 of the closing body 12, the distal end portion 22 of the elongated wire electrode 20 passing through the main pipe 10 is located. A positioning insulator is attached to the distal end side of the wire electrode 20. A positioning insulator 24 is mounted to prevent the tip side from swinging. The wire electrode 20 constitutes a positive electrode, and tungsten (melting point: 3380 ° C.) is used to suppress consumption due to discharge. The wire electrode 20 is covered with an insulating tube 26, and the base end side passes through the main pipe 10 and the electrode side pipe 104 branched from the main pipe 10, and a connection terminal 28 is attached to the base end. It has been.

  In the liquid L to be processed, a plate electrode 30 constituting a negative electrode is arranged. In the present embodiment, a stainless plate (SUS304) having strength and high corrosion resistance is used as a material for the plate electrode 30.

FIG. 4 is a block diagram showing an embodiment of an apparatus for sending ozone as a gas and a pulse voltage as an applied voltage to an in-liquid plasma generator.
In the figure, a DC power supply 40 outputs DC 1 KV when AC 100 V is input. The air pump 41 sends air to an ozone generator (ozonizer) 42 to generate ozone. Ozone generated by the ozone generator 42 and air components such as nitrogen, oxygen, and argon are sent to the main pipe 10 via the air supply pipe 102 and sent from the closing body 12 into the liquid L to be processed as fine bubbles. In addition, it can also be set as the structure which sends the other gas containing the air which does not contain ozone, or oxygen.

A clock signal for control is sent from the microcomputer 43 to the gate circuit 44, and a pulse is sent to the wire electrode 20 through the gate circuit 44.
A clock signal for control is sent from the microcomputer 43 to the gate circuit 44, and a pulse signal for applying a voltage to the electrodes is output.
The pulse voltage generator is not limited to the above-mentioned device, and various known devices are preferably used.

(Function)
The plate electrode 30 is disposed on the bottom of a processing tank for processing a liquid to be processed such as a factory waste liquid, and the tip of the main pipe 10 is submerged in the liquid to be processed. Facing each other.

  The air pump 41 is operated to send air to the ozone generator 42 to generate ozone. The generated ozone is sent to the main pipe 10 via the air supply pipe 102, and is discharged into the liquid to be treated as fine bubbles of ozone from the closing body 12 at the lower end of the main pipe 10.

  After the released ozone becomes fine bubbles and the lower end of the main pipe 10 is surrounded by the fine bubbles, when a pulse voltage is applied to the wire electrode 20, an arc is generated between the tip 22 of the wire electrode 20 and the plate electrode 30. A discharge is generated and plasma is generated to generate OH radicals and ozone.

  The generated OH radicals and ozone are diffused in the liquid to be processed together with the fine bubbles of ozone to process the liquid to be processed.

  Note that the terms and expressions used in this specification are merely explanatory and are not limiting at all, and terms and expressions equivalent to the features described in this specification and parts thereof. There is no intention to exclude. It goes without saying that various modifications are possible within the scope of the technical idea of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be used in various fields in which discharge is caused in a liquid to generate OH radicals and ozone and use them.

DESCRIPTION OF SYMBOLS 10 Main pipe 11 End spread part 12 Closure body 20 Wire electrode 22 Tip part 24 Positioning insulator 26 Insulation tube 28 Connection terminal 30 Plate electrode 40 Power supply 41 Air pump 42 Ozone generator 43 Microcomputer 44 Gate circuit 102 Supply pipe 104 Electrode side Tube 120 Hollow part L Liquid to be treated

Claims (2)

A submerged plasma generator for arranging a positive electrode and a negative electrode in a liquid and applying a voltage to the positive electrode to generate a plasma in the liquid,
Provided with fine bubble generating means (102, 10, 12) for generating fine bubbles by directly supplying gas into the liquid from the outside, either one or both of the positive electrode (20) and the negative electrode (30) , Disposed in an isolation element (12) having a gas passage element to isolate the liquid from the liquid, the isolation element (12) constitutes a fine bubble generating means, and gas from the isolation element (12) is contained in the liquid To generate a fine bubble in the liquid to generate a plasma in the liquid by applying a voltage to the positive electrode (20),
In-liquid plasma generator. An electrode device for plasma in liquid that generates plasma in liquid,
(10)
An air supply element (102) for sending gas to the main pipe (10);
A porous closing element (12) that closes the opening of the main pipe (10) and discharges the gas that has passed through the main pipe (10) into the liquid as fine bubbles;
A wire electrode (20) located in the space (120) formed by the main pipe (10) and the porous closure element (12), and provided close to the porous closure element (12);
With
In-liquid plasma generating electrode device.

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