JP2019155294A - Water treatment device - Google Patents

Abstract

To provide a water treatment device that stably generates plasma.SOLUTION: A discharge unit 101, a plasma generation power source 103, and a plasma advancing unit 102 are provided, and the discharge unit 101 is provided with a high voltage electrode 101a, a ground electrode 101b that does not have water to be treated between itself and the high voltage electrode 101a, and a dielectric electrode 101c provided between the high voltage electrode and the ground electrode. A rare gas is present between the high voltage electrode 101a and the ground electrode 101b, and the region where the water to be treated W flows is provided apart. The plasma generation power source 103 applies a voltage between the high voltage electrode 101a and the ground electrode 101b to ignite plasma in the rare gas. The plasma advancing unit 102 releases the plasma ignited in the rare gas from a second opening 102b opposite to a first opening 102a to the water to be treated W, and generates radicals in the water to be treated, to decompose poorly decomposable materials.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a water treatment apparatus.

  For the treatment of water and sewage, ozone treatment and chlorination are generally used. However, industrial wastewater may contain difficult-to-decompose substances such as dioxins and dioxane that are not decomposed by ozone treatment or chlorination. Oxygen radicals (OH radicals), which are more reactive than ozone treatment and chlorination treatment, are generated in water to be treated such as industrial wastewater by the accelerated oxidation treatment method using ozone, hydrogen peroxide, and ultraviolet rays. There is a method for decomposing difficult-to-decompose substances. However, the accelerated oxidation treatment method has a very high cost for an apparatus for executing the enhanced oxidation treatment method and its operation.

  Therefore, a water treatment apparatus has been proposed that generates OH radicals in the water to be treated by the action of plasma and decomposes the hardly decomposed substances in the water to be treated with high efficiency. This water treatment apparatus generates plasma by applying a pulse voltage between a wire-like high-voltage electrode and a flat ground electrode, and at the same time tilts the ground electrode and allows water to be treated to flow along its upper surface. A liquid layer is formed, and the liquid layer is irradiated with plasma to decompose a hardly decomposed substance in the water to be treated by OH radicals generated in the water to be treated. In addition, a pulse voltage is applied between the wire-like high-voltage electrode and the flat ground electrode to generate plasma, and a part of the water to be treated that flows on the upper surface of the ground electrode is formed into water droplets, so that Technology has been developed for more efficient decomposition of difficult-to-decompose substances.

Japanese Patent No. 5819031

  However, in the above water treatment apparatus, since the water to be treated is introduced between the high voltage electrode and the ground electrode, the plasma generated between the high voltage electrode and the ground electrode generates the shape of the water to be treated and the conductivity of the water to be treated. Under the influence of the electrical properties of the water to be treated such as the dielectric constant and the dielectric constant, it may become unstable or become susceptible to abnormal discharge (spark discharge). Therefore, in the above-described water treatment apparatus, in order to stably generate plasma, the voltage applied between the high voltage electrode and the ground electrode is set to a voltage sufficiently higher than the discharge start voltage, and between the high voltage electrode and the ground electrode. Therefore, it is necessary to apply a pulse voltage having a short pulse width. This requires special measures of power supply and insulation measures for the water treatment device itself. Furthermore, there is a high possibility that the power consumption efficiency of the power supply that applies a voltage between the high-voltage electrode and the ground electrode will deteriorate.

  The water treatment apparatus according to the embodiment includes a discharge unit, a plasma generation power source, and a plasma progress unit. The discharge unit includes a high voltage electrode, a ground electrode provided without water to be treated between the high voltage electrode, and a dielectric electrode provided between the high voltage electrode and the ground electrode, A rare gas is present between the high voltage electrode and the ground electrode, and is provided apart from the region through which the water to be treated flows. The plasma generating power source applies a voltage between the high voltage electrode and the ground electrode, and ignites the plasma in a rare gas between the high voltage electrode and the ground electrode. The plasma advancing portion is a cylindrical insulator, and the plasma is ignited in the rare gas inside from the first opening by the action of the plasma ignited in the rare gas between the high voltage electrode and the ground electrode, The plasma is discharged from the second opening opposite to the first opening to the water to be treated, and radicals are generated in the water to be treated.

Drawing 1 is a figure showing an example of the composition of the water treatment equipment concerning a 1st embodiment. Drawing 2 is a figure showing an example of the composition of the water treatment equipment concerning a 2nd embodiment. Drawing 3 is a figure showing an example of the composition of the water treatment equipment concerning a 3rd embodiment. FIG. 4 is an example of a perspective view of a water treatment apparatus according to the fourth embodiment. FIG. 5: is an example of the figure which looked at the water treatment apparatus concerning 4th Embodiment from upper direction. FIG. 6 is an example of a perspective view of a water treatment apparatus according to the fifth embodiment.

  Hereinafter, the water treatment apparatus according to the present embodiment will be described with reference to the accompanying drawings.

(First embodiment)
Drawing 1 is a figure showing an example of the composition of the water treatment equipment concerning a 1st embodiment. As shown in FIG. 1, the water treatment apparatus according to this embodiment includes a discharge unit 101, a plasma progressing unit 102, and a plasma generation power source 103. The discharge unit 101 includes a high-voltage electrode 101a, a ground electrode 101b, and a dielectric electrode 101c, and water to be treated W (for example, industrial wastewater or water and sewage water containing a hardly decomposed substance such as dioxins or dioxane). It is provided apart from the flowing region. In other words, the discharge part 101 is electrically insulated from the region through which the water to be treated W flows, and is generated in the discharge part 101 under the influence of the shape of the water to be treated W and the electrical properties of the water to be treated W. It is only necessary to provide the plasma so that it does not become unstable or abnormal discharge is likely to occur. In the present embodiment, the discharge unit 101 is provided approximately 20 cm above the liquid level of the water to be treated W. The high voltage electrode 101a is made of a conductive material. The high voltage electrode 101a is an electrode to which a voltage is applied by a plasma generation power source 103 described later. In addition, the to-be-processed water W shall flow in the direction D of FIG.

  The ground electrode 101b is an electrode provided without the treated water W between the high voltage electrode 101a. The ground electrode 101b is made of a conductive material, like the high voltage electrode 101a. A plasma generating gas G exists between the high voltage electrode 101a and the ground electrode 101b. In the present embodiment, the ground electrode 101b is a cylindrical (for example, cylindrical) electrode provided outside the high voltage electrode 101a. In the present embodiment, the plasma generating gas G is introduced from the upper opening of the cylindrical ground electrode 101b, and the space between the high voltage electrode 101a and the ground electrode 101b is filled with the plasma generating gas G. Alternatively, the plasma generating gas G may be filled in advance between the high voltage electrode 101a and the ground electrode 101b. Here, the plasma generating gas G is a rare gas (for example, Ar gas or the like) that can apply a voltage between the high-voltage electrode 101a and the ground electrode 101b to ignite (generate) plasma with high efficiency. He gas). The dielectric electrode 101c is made of a dielectric and is an electrode provided between the high voltage electrode 101a and the ground electrode 101b. In the present embodiment, the dielectric electrode 101c is a cylindrical (for example, cylindrical) electrode provided inside the ground electrode 101b and disposed coaxially with the ground electrode 101b. In the present embodiment, the outer peripheral surface of the dielectric electrode 101c is in contact with the inner peripheral surface of the ground electrode 101b.

  The plasma generation power source 103 applies a voltage between the high voltage electrode 101a and the ground electrode 101b to ignite plasma in the plasma generation gas G between the high voltage electrode 101a and the ground electrode 101b. In the present embodiment, the plasma generation power source 103 generates plasma in the discharge unit 101 by generating an electric discharge by applying an AC voltage having a frequency of 15 kHz and several kV between the high voltage electrode 101a and the ground electrode 101b. Is fired. In the present embodiment, the plasma generation power source 103 applies an alternating voltage having a frequency of 15 kHz and a voltage of several kV between the high voltage electrode 101a and the ground electrode 101b, but the high voltage electrode 101a and the ground electrode 101b are applied. If it is a frequency and voltage which can ignite a plasma in the gas G for plasma production between, it will not be limited to this.

  The plasma propagation part 102 is a cylindrical insulator (for example, polyvinyl chloride, glass, ceramics). Further, the plasma advancing portion 102 is moved from one opening 102a (hereinafter referred to as the first opening) to the inside by the action of plasma ignited in the plasma generating gas G between the high voltage electrode 101a and the ground electrode 101b. Plasma is ignited in the plasma generating gas G. In this embodiment, the plasma progressing part 102 is a cylindrical member arranged coaxially with the ground electrode 101b, and the first opening 102a is connected to the opening of the dielectric electrode 101c. In the present embodiment, the first opening 102a of the plasma progressing portion 102 is connected to the opening of the dielectric electrode 101c, but is ignited in the plasma generating gas G between the high voltage electrode 101a and the ground electrode 101b. If the plasma can be ignited in the plasma generating gas G in the plasma progressing part 102 by the action of the plasma, it may be provided apart from the discharge part 101.

  Here, the plasma generating gas G is a rare gas (for example, Ar gas) that can ignite (generate) plasma with high efficiency in the plasma advancing unit 102 by the action of the plasma generated by the discharge unit 101. Or He gas). In the present embodiment, the plasma generating gas G may be filled in the plasma progressing portion 102 in advance, or may flow into the plasma progressing portion 102 from the first opening 102a.

  Further, the plasma advancing unit 102 causes the plasma to be ignited in the plasma generating gas G in the plasma advancing unit 102 from an opening 102b (hereinafter referred to as a second opening) opposite to the first opening 102a. Release to generate radicals in the water W to be treated. In this embodiment, the 2nd opening 102b is provided above the flow path through which the to-be-processed water W flows, and has the distance below the predetermined distance L between the liquid levels of the to-be-processed water W. Here, the predetermined distance L is a distance (for example, several mm) that is equal to or less than a threshold value of a distance that the plasma generated in the plasma progressing part 102 can move in the air.

  According to the above configuration, the electric field formed by the plasma itself that is ignited in the plasma generating gas G in the discharge unit 101 is the starting point, and the plasma generating gas G in the plasma progressing unit 102 is in the starting point. The plasma is ignited. The plasma ignited in the plasma progressing part 102 moves (advances and forms) from the first opening 102a toward the second opening 102b, and is released toward the liquid surface of the water W to be treated from the second opening 102b. The The plasma emitted from the second opening 102b is applied to the liquid surface of the water W to be treated. And a water treatment apparatus implement | achieves the process (henceforth water treatment) which decomposes | disassembles the hardly decomposable harmful substance etc. which are contained in the to-be-processed water W with the plasma discharge | released from the 2nd opening 102b.

  Thereby, plasma can be irradiated with respect to the to-be-processed water W, without making the to-be-processed water W flow in between the high voltage electrode 101a and the ground electrode 101b, and the shape of the to-be-processed water W, the to-be-processed water W of Since plasma can be generated without being affected by electrical properties (for example, conductivity and dielectric constant), the plasma generated in the plasma generating gas G between the high voltage electrode 101a and the ground electrode 101b is reduced. The plasma can be stably generated by preventing instability and occurrence of abnormal discharge by the plasma. In addition, since the plasma generating gas G flows into the plasma progressing portion 102, it is possible to generate plasma in the plasma progressing portion 102 at a low voltage that is easy to insulate against the water to be treated W. Furthermore, since it becomes easy to use a general-purpose power source as the plasma generation power source 103 and the insulation measures of the water treatment device are easy, a water treatment device capable of performing water treatment at low cost and high efficiency is provided. It becomes possible. Further, since the power consumption of the plasma generation power supply 103 can be reduced, the power consumption of the entire water treatment apparatus can also be reduced.

  Next, water treatment for decomposing difficult-to-decompose harmful substances contained in the water to be treated with plasma emitted from the second opening 102b of the plasma progressing portion 102 will be specifically described. When the plasma emitted from the second opening 102b comes into contact with the water to be treated W, reactive OH radicals which are chemically active species are generated in the water to be treated W, and the water to be treated is generated by the generation of the OH radicals. The hard-to-decompose harmful substances contained in W are decomposed.

More specifically, the plasma emitted from the second opening 102b comes into contact with the liquid surface of the water to be treated W, so that the positive ions in the plasma become water molecules (H ₂ O) in the water to be treated W. Water molecule ions (H ₂ O ⁺ ) are generated through charge exchange. Furthermore, water molecule ions (H ₂ O ⁺ ) are exchanged with water molecules (H ₂ O) of the water W to be treated, and hydronium ions (H ₃ O ⁺ ) and OH radicals are generated in the water to be treated W.
H ₂ O ⁺ + H ₂ O → H ₃ O ⁺ + OH (1)

Moreover, the OH radical in the to-be-processed water W is produced | generated in the to-be-processed water W by other than reaction shown by Formula (1). Specifically, the photoionization of water molecules (H ₂ O) in the water W to be treated by UV light (ultraviolet light) or VUV light (vacuum ultraviolet light) generated by plasma generated in the plasma progressing part 102. It is also possible to generate OH radicals in the water to be treated W by charge exchange starting from. Furthermore, OH radicals are generated in the gas phase near the liquid surface of the water to be treated W by the plasma generated in the plasma progressing part 102, and the OH radicals are dissolved in the water to be treated W. It is also possible to generate OH radicals in W.

  Thus, according to the water treatment apparatus according to the first embodiment, the water to be treated W is irradiated with plasma without flowing the water to be treated W between the high voltage electrode 101a and the ground electrode 101b. Since plasma can be generated without being affected by the shape of the water to be treated W and the electrical properties (for example, conductivity and dielectric constant) of the water to be treated W, the high voltage electrode 101a and the ground The plasma generated between the electrodes 101b can be prevented from becoming unstable, or abnormal discharge can be prevented from being generated by the plasma, so that the plasma can be generated stably.

(Second Embodiment)
The present embodiment is an example in which the plasma progressing portion is configured by a flexible insulator. In the following description, description of the same configuration as that of the first embodiment is omitted.

  Drawing 2 is a figure showing an example of the composition of the water treatment equipment concerning a 2nd embodiment. As shown in FIG. 2, the water treatment apparatus according to this embodiment includes a discharge unit 101, a plasma progressing unit 202, and a plasma generation power source 103. In the present embodiment, the plasma progressing part 202 is configured by a flexible insulator. Thereby, since the freedom degree of arrangement | positioning of the discharge part 101 with respect to the liquid level of the to-be-processed water W can be improved by deform | transforming the plasma progress part 202, the space which installs a water treatment apparatus can be made small. .

  Moreover, since the position of the 2nd opening 102b can be moved on the liquid level of the to-be-processed water W by moving the plasma expansion part 202, the plasma discharge | released from the 2nd opening 102b can be wide in the to-be-processed water W. Irradiation to the region can be performed in a short time, and the efficiency of water treatment for decomposing hardly decomposed substances contained in the water to be treated W can be improved. Here, the flexible insulator is preferably silicon rubber or fluororesin, but may be any material that has an insulating property and can fill the inside with the plasma generating gas G. .

  Thus, according to the water treatment apparatus concerning 2nd Embodiment, the freedom degree of arrangement | positioning of the discharge part 101 with respect to the liquid level of the to-be-processed water W can be improved by deform | transforming the plasma expansion part 202. FIG. Therefore, the space for installing the water treatment device can be reduced.

(Third embodiment)
The present embodiment is an example in which the area of the second opening of the plasma progressing portion is made larger than the area of the first opening of the plasma progressing portion. In the following description, description of the same configuration as that of the first embodiment is omitted.

  Drawing 3 is a figure showing an example of the composition of the water treatment equipment concerning a 3rd embodiment. As shown in FIG. 3, the water treatment apparatus according to this embodiment includes a discharge unit 101, a plasma progressing unit 302, and a plasma generation power source 103. In the present embodiment, the shape (inner cross-sectional shape) and area of the second opening 102b of the plasma progressing portion 302 is different from the shape (inner cross-sectional shape) and area of the first opening 102a. Specifically, the plasma progressing part 302 makes the area of the second opening 102b larger than the area of the first opening 102a. Accordingly, since the plasma emitted from the second opening 102b can be irradiated to the wide range of the water to be treated W in a short time without moving the plasma progressing portion 302, more water to be treated. Water treatment can be efficiently performed on W. Moreover, it is preferable that the width | variety of the 2nd opening 102b is more than the width | variety of the flow path through which the to-be-processed water W flows.

  As described above, according to the water treatment apparatus according to the third embodiment, the plasma emitted from the second opening 102b is made shorter than the wide range of the water to be treated W without moving the plasma progressing portion 302. Since it can irradiate with time, water treatment can be efficiently performed with respect to more to-be-treated water W.

(Fourth embodiment)
The present embodiment is an example in which the discharge unit includes a plurality of high voltage electrodes. In the following description, description of the same configuration as that of the first embodiment is omitted.

  FIG. 4 is an example of a perspective view of a water treatment apparatus according to the fourth embodiment. FIG. 5: is an example of the figure which looked at the water treatment apparatus concerning 4th Embodiment from upper direction. In this embodiment, the water treatment apparatus includes a discharge unit 401, a plasma progressing unit 102, and a plasma generation power source 103. The discharge unit 401 includes a plurality of high voltage electrodes 101a. Accordingly, it is possible to ignite plasma in a wider area in the discharge unit 401, and it is possible to increase the plasma to be ignited in the plasma generating gas G in the plasma advancing unit 102. By irradiating plasma over a wider area with respect to W, water treatment for the water to be treated W can be performed efficiently. In the present embodiment, the plurality of high voltage electrodes 101a are provided inside a cylindrical ground electrode 101b. In other words, the discharge unit 401 includes a plurality of high voltage electrodes 101a that generate a discharge with respect to one ground electrode 101b. Further, in the present embodiment, the plurality of high voltage electrodes 101 a are connected in parallel to one plasma generation power source 103.

  As described above, according to the water treatment apparatus of the fourth embodiment, it is possible to ignite plasma in a wider region in the discharge unit 401, and the plasma generation gas G in the plasma progressing unit 102 can be ignited. Since the plasma to be arced can be increased, it is possible to efficiently perform water treatment on the water to be treated W by irradiating the water to be treated W with a larger area.

(Fifth embodiment)
The present embodiment is an example including a plurality of sets of discharge parts and plasma progressing parts. In the following description, description of the same configuration as that of the first embodiment is omitted.

  FIG. 6 is an example of a perspective view of a water treatment apparatus according to the fifth embodiment. As shown in FIG. 6, the water treatment apparatus according to the present embodiment includes a plurality of sets 601 (hereinafter referred to as plasma emission units) including the discharge unit 101 and the plasma progressing unit 102 in addition to the plasma generation power source 103. . In the present embodiment, the high voltage electrode 101 a included in the discharge unit 101 of each plasma emission unit 601 is connected in parallel to the plasma generation power source 103.

  As a result, the plasma emitted from the second opening 102b can be irradiated in a short time to a wide range of the water to be treated W, so that water treatment can be efficiently performed on more water to be treated W. it can. In the present embodiment, the high-voltage electrode 101a included in the discharge unit 101 of each plasma emission unit 601 is connected in parallel to one plasma generation power source 103. However, the present invention is not limited to this. The high voltage electrode 101 a included in the discharge unit 101 of the unit 601 may be connected to different plasma generation power sources 103.

  Thus, according to the water treatment apparatus concerning 5th Embodiment, since the plasma discharge | released from the 2nd opening 102b can be irradiated with respect to the wide range of the to-be-processed water W in a short time, more A water treatment can be efficiently performed with respect to many to-be-processed water Ws.

  As described above, according to the first to fifth embodiments, it is possible to prevent the plasma generated between the high voltage electrode 101a and the ground electrode 101b from becoming unstable or causing abnormal discharge due to the plasma. Thus, plasma can be generated stably.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 101,401 Discharge part 101a High voltage electrode 101b Ground electrode 101c Dielectric electrode 102,202,302 Plasma progress part 102a 1st opening 102b 2nd opening 103 Power supply for plasma generation 601 Plasma discharge part W Water to be treated

Claims (5)

A high-voltage electrode, a ground electrode provided between the high-voltage electrode without any water to be treated, and a dielectric electrode provided between the high-voltage electrode and the ground electrode. A rare gas is present between the voltage electrode and the ground electrode, and a discharge part provided apart from a region through which the water to be treated flows;
A plasma generating power source for applying a voltage between the high voltage electrode and the ground electrode to ignite plasma in a rare gas between the high voltage electrode and the ground electrode;
It is a cylindrical insulator, and the plasma is ignited in the rare gas inside from the first opening by the action of the plasma ignited in the rare gas between the high voltage electrode and the ground electrode. A plasma advancing portion that discharges from the second opening opposite to the first opening to the water to be treated and generates radicals in the water to be treated;
A water treatment apparatus comprising:   The water treatment apparatus according to claim 1, wherein the plasma advancing portion is a flexible insulator.   The water treatment apparatus according to claim 1 or 2, wherein an area of the second opening is larger than an area of the first opening.   The said discharge part is a water treatment apparatus as described in any one of Claim 1 to 3 which has several said high voltage electrode.   The water treatment apparatus according to any one of claims 1 to 4, comprising a plurality of sets of the discharge part and the plasma progressing part.

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