JP2000107754A - Liquid treatment apparatus by plasma - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the distance between a liquid film surface and an electrode constant surely by a method in which a high frequency pulse voltage is applied between a vertical pipe and a concentric cylinder, and plasma generated by discharge is made to act on a liquid film flowing down along the inner wall of the vertical pipe. SOLUTION: A high frequency pulse voltage is applied between vertical pipe 3 and the anode rod 9 of a concentric cylinder installed at the center of the vertical pipe 3 by a high frequency pulse voltage generator 8, and under specified conditions of the clearance between a disk-shaped fin 12 and the pipe 3 or the clearance between the pipe 3 and raw liquid by the conductivity of the raw liquid 1, voltage to be applied and its frequency, and others, high frequency corona discharge is stated between both poles so that plasma is generated continuously. Strong oxidation factors such as ultraviolet rays, ozone, and free radicals which are generated by the plasma are made to act on a liquid film flowing down along the inner wall of the pipe 3. In this way, the distance between the liquid film and the electrode can be kept constant to improve the action effect of the plasma.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for oxidizing, purifying and sterilizing liquids such as water and sewage and drinks such as milk using discharge plasma.

[0002]

2. Description of the Related Art In recent years, there have been proposed various techniques for treating contaminants with plasma generated by discharge by applying a high-frequency pulsed voltage between electrodes under atmospheric pressure. Then, water is allowed to fall freely from the concentric gaps to form a hollow cylindrical water flow, and a high-frequency pulsed voltage is applied between the electrodes provided on the inner and outer surfaces of this water flow to generate discharge plasma between the electrodes. Oxidizes water pollution and bacteria
There is a detoxifying method. This was introduced at the international trade fair IFAT held in Munich in 1996, but its configuration is compact and the ultraviolet and
Since strong oxidizing factors such as ozone and free radicals effectively act on water streams, they have been attracting attention as purification and sterilization treatment devices for liquids such as water and sewage and drinks such as milk.

[0003]

However, if the liquid to be treated is water, it is conductive. If the gap between the water flow and the electrode becomes extremely narrow, a local short circuit occurs, causing a transition from corona discharge to spark discharge. In order to maintain stable discharge plasma by the above method, it is necessary to maintain a constant gap between the discharge electrode and the water flow. However, since it is difficult to accurately control the size and shape of the hollow cylindrical water flow that has been freely dropped, it is not always easy to satisfy this requirement and maintain stable plasma.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems and to further improve the action and effect of the plasma, the inventor of the Japanese Patent Application Laid-Open No. 6-238266, entitled "Method and Apparatus for Irradiating Electromagnetic Wave to Liquid", was filed earlier. The method, that is, “a method of irradiating the liquid film flowing down the inner wall of the vertical tube with the electromagnetic wave from the inside” was used.

That is, according to the first aspect of the present invention, a plasma generated by discharge by applying a high-frequency pulsed voltage between a vertical tube and a concentric cylinder provided at the center of the vertical tube is provided.
A plasma-based liquid processing apparatus characterized by acting on a liquid film flowing down an inner wall of a vertical tube.

Further, the invention according to claim 2 effectively utilizes the existence of a vertical tube in order to further enhance the effect of the plasma. In the liquid processing apparatus using plasma according to claim 1, the vertical tube is used. Is characterized by providing fine irregularities on the inner wall.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a view taken along the line XX of FIG. 1, FIG. 3 is a detailed view of a portion P in FIG. 1, FIG. FIG. 5 is a view taken along the line YY in FIG. 4. In the drawings, the same reference numerals denote the same or corresponding parts.

Referring to FIGS. 1 to 3, an embodiment of the present invention will be described. A liquid 1 to be treated, such as water and sewage and a drink such as milk, overflows a top 4 of a vertical pipe 3 suspended from an upper liquid retaining tank 2. The flow rate is controlled so that the inner wall of the vertical pipe 3 flows down in a film form and is supplied to the upper liquid holding tank 2, and the purified liquid 6 is passed through the lower liquid tank 5.
It is configured to flow out. The inner wall of the vertical tube 3 is provided with fine irregularities as shown in the figure for the purpose of increasing the surface area of the liquid film flowing down therethrough and generating a vortex 7 in the liquid to constantly change the liquid surface.
On the other hand, a positive electrode rod 9 connected to a well-known high-frequency pulsed voltage generator 8 hangs from the top of the upper liquid holding tank 2, and a conductive cylinder 10 is concentrically formed on the positive electrode rod 9 with the vertical tube 3. Conductive support members 11 are connected to each other, and conductive disc-shaped fins 12 are provided on the outer periphery of the cylinder 10 at equal intervals while maintaining a gap G-1 with the outer periphery of the vertical tube 3.

In the above configuration, when a high-frequency pulse voltage is applied between the positive electrode rod 9 and the grounded vertical tube 3 by the high-frequency pulse voltage generator 8, the disk-shaped fin 12 (anode) and the vertical tube Under specific conditions, such as the gap G-1 to the cathode 3 and the gap G-2 between the vertical tube 3 and the liquid 1 to be processed, the applied voltage and its frequency, depending on the conductivity of the liquid 1 to be processed. A high-frequency corona discharge is started between the plasmas to continuously generate plasma, and strong oxidizing factors such as ultraviolet rays, ozone, and free radicals generated by the plasma act on the liquid 1 to be processed to perform oxidation purification, sterilization, and the like. Done.
In addition, when the purification is insufficient by one treatment, the treatment may be repeated and repeated.

FIGS. 4 and 5 show another embodiment in which the processing scale is large. A large number of vertical tubes 3 suspended from the upper liquid holding tank 2 and a plurality of vertical tubes 3 are provided corresponding to the vertical tubes 3. A large number of positive electrode rods 9, conductive cylinders 10, conductive disc-shaped fins 12,
And a high frequency pulse voltage generator 8 common to them,
The processing mode for the liquid film formed by flowing down the inner wall of each vertical tube 3 is the same as described above.

[0011]

As is apparent from the above description, according to the first aspect of the present invention, the liquid flow is not free falling but flows down the inner wall of the vertical tube, so that the liquid flow is stabilized and the liquid film is formed. The distance between the surface and the electrode can be reliably kept constant. Therefore,
Even in the case of the conductive water treatment, the gap between the water flow and the electrode is extremely narrowed, and a local short circuit occurs, so that a more stable discharge plasma can be maintained without shifting to spark discharge.

According to the second aspect of the present invention, the fine irregularities provided on the inner wall of the vertical tube increase the surface area of the liquid film, generate a vortex in the liquid film, and constantly replace the liquid surface. Since the contact area between the strong oxidizing factors such as ultraviolet rays, ozone, and free radicals generated by the plasma and the liquid is substantially increased, the effect of the plasma can be enhanced.

[Brief description of the drawings]

FIG. 1 shows a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 shows a view taken along the line XX of FIG.

FIG. 3 shows a detailed view of a part P in FIG. 1;

FIG. 4 shows a longitudinal sectional view of another embodiment of the present invention.

FIG. 5 shows a view taken along the line YY of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 To-be-processed liquid 2 Upper liquid storage tank 3 Vertical pipe 5 Lower liquid tank 6 Purification liquid 7 Eddy current 8 High frequency pulsed voltage generator 9 Positive electrode rod 10 Conductive cylinder 11 Conductive support material 12 Conductive disk-shaped fin

Claims (2)

[Claims] In a method of irradiating a liquid film flowing down the inner wall of a vertical tube with an electromagnetic wave, a high-frequency pulsed voltage is applied between the vertical tube and a concentric cylinder provided at the center of the vertical tube. A plasma generated by the electric discharge to act on a liquid film flowing down the inner wall of the vertical tube. 2. The plasma-based liquid processing apparatus according to claim 1, wherein fine irregularities are provided on the inner wall of the vertical tube.