JP2009091209A - Discharge tube for ozone generation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge tube made of quartz and cooled by water from both surfaces which can generate more ozones in the same scale as that in a conventional triple tube structure with an inner surface cooled by water and an outer surface cooled by air. <P>SOLUTION: Provided is a discharge tube which has a quartz triple tube structure with both inner and outer sides cooled by water, wherein the cooling water of the high voltage side is supplied and discharged through an insulated pipe. Namely, ozone is generated by flowing cooling water in the gap 6 between the outer quartz tube 1 and the middle quartz tube 2 and by flowing cooling water inside 13 of the inner quartz tube 3, by applying a high alternating voltage between the both cooling water to form a high alternating electric field in the gap 25 between the inner quartz tube 3 and the middle quartz tube 2 and to generate a silent discharge. In particular, for the part 6 of the cooling water where the high voltage is applied the cooling water is supplied and discharged through insulated pipes 20, 21 having electric resistance including water of 1 MΩ or larger. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge part of an ozone generator that generates ozone by discharge in gas.

  Ozone generators using the silent discharge method have become widespread. This generates ozone by generating an electric discharge while flowing an oxygen-containing gas between the metal and the solid dielectric, or between the solid dielectric and the solid dielectric, or between the metal and the metal coated with the solid dielectric.

  For example, a glass tube whose inner surface is coated with an electrically conductive material is placed inside a stainless steel tube, and a gas for generating ozone such as dry air or oxygen is sent between the stainless tube and the electrically conductive material on the inner surface of the glass tube. An alternating current high voltage having a voltage effective value of 5 to 10 kV and a frequency of 50 to 5000 Hz is loaded between the tube and the inner surface of the glass tube to generate discharge in the ozone generating gas to generate ozone.

  In particular, a discharge tube having a quartz double tube structure has been put into practical use in order to generate high-purity ozone without generating metal dust. An example of the structure of such a discharge tube is described in, for example, Japanese Patent Laid-Open No. 06-048707. In this structure, an electrically conductive material is bonded to the inner surface of the inner tube of two quartz tubes sharing the central axis, and an AC high voltage having a voltage effective value of 8 to 15 kV and a frequency of about 1000 to 20000 Hz is loaded. The outer surface is cooled with water and held at the ground potential.

  By the way, such a conventional stainless steel and glass double tube structure or a quartz double tube structure silent discharge ozone generator discharge tube covers a part of a glass tube or a quartz tube with an electrically conductive film. At the time of disposal, it is usually treated as industrial waste, which has environmental problems.

Japanese Patent Application Laid-Open No. 2004-269326 has filed an application for a discharge tube having a quartz triple tube structure as an invention having an object to solve such problems.
According to the present invention, all the main parts of the discharge tube are made of quartz, which has the advantage of being recyclable. By the way, this invention employs a cooling method in which the inner surface of the discharge tube is water-cooled and the outer surface is air-cooled. That is, cooling water is circulated through the innermost quartz tube to cool it, and an electrolytic solution is sealed between the outer quartz tube and the intermediate quartz tube, and the electrolytic solution is forcibly air-cooled from the outer surface.

In this case, when the discharge output is increased, the electrolytic solution is heated and starts to boil, so that it is necessary to use the electrolyte within a certain range of output according to the scale of the discharge tube. As a result, the ozone generation amount has a certain limit.
For example, a discharge tube in which the diameter of the outermost quartz tube is 25 mm, the length is 158 mm, the diameter of the intermediate quartz tube is 18 mm, the length is 200 mm, the diameter of the innermost quartz tube is 15 mm, and the length is 230 mm is used. The limit of power that can be supplied to the discharge unit is about 250 W, and the amount of ozone generated by the power is about 15 g / hr using 5 l / min of oxygen.
Japanese Patent Laid-Open No. 06-048707 JP 2004-269326 A

  The present invention does not cover the quartz part with an electrically conductive film, the quartz part and other parts can be easily disassembled and the quartz part can be recycled, and is the same as the conventional quartz triple tube structure with internal water cooling and external air cooling. An object of the present invention is to provide a double-sided water-cooled quartz discharge tube capable of generating more ozone on a scale.

  In order to solve the above problems, the present invention employs a quartz triple tube discharge tube, and the cooling is water-cooled on both the inside and the outside, but the cooling water on the high voltage side is supplied through an insulating pipe. Discharge.

  That is, the cooling water is circulated through the gap 6 between the outer quartz tube 1 and the intermediate quartz tube 2, and the cooling water is circulated through the inside 13 of the inner quartz tube 3, and an AC high voltage is loaded between both the cooling waters. Then, ozone is generated by generating an alternating high electric field in the gap 25 between the inner quartz tube 3 and the intermediate quartz tube 2 and generating a silent discharge.

  In particular, the cooling water portion 6 to which high voltage is loaded is supplied and discharged through insulating pipes 20 and 21 having an electrical resistance of 1 MΩ or more including the cooling water.

  According to the present invention, no portion of the discharge tube is covered with a conductive film, and can be easily disassembled and the quartz portion can be recycled, and the conventional water-cooled and outer-air-cooled quartz triple tube system described in Japanese Patent Application Laid-Open No. 2004-269326 A discharge tube capable of generating 1.7 times the amount of ozone on the same scale was realized.

Additional explanation regarding the effects of the invention: Ozone generation amount in the examples The ozone generation amounts for the examples of 500 W and 1000 W as the electrical output (including power loss) are 25 g / hr and 50 g / hr, respectively. Next, some details of these examples will be described.

  In the embodiment of 500 W, the diameter of the outer quartz tube 1 in FIG. 1 is 25 mm, the length is 158 mm, the diameter of the intermediate quartz tube 2 is 18 mm, the length is 200 mm, the diameter of the inner quartz tube is 15 mm, and the length is 230 mm. Using a discharge tube, an ozone generation amount of 25 g / hr is obtained using oxygen as a raw material at a flow rate of 5 liters at a frequency of 20 kHz, an effective voltage value of 9 kV, and an electric output of 500 w (including power loss, the same applies hereinafter). .

  In the example of 1000 W, the diameter of the outer quartz tube 1 in FIG. 1 is 25 mm, the length is 316 mm, the diameter of the intermediate quartz tube 2 is 18 mm, the length is 360 mm, the diameter of the inner quartz tube is 15 mm, and the length is 390 mm. Using a discharge tube, an ozone generation amount of 25 g / hr was obtained with a frequency of 20 kHz, a voltage effective value of 9 kV, and an electrical output of 1000 W, using oxygen per a flow rate of 10 liters as a raw material.

  In the case of the existing water cooling and outer air cooling described in Japanese Patent Application Laid-Open No. 2004-269326, a discharge tube of the same scale as the above 500 W embodiment has a frequency of 15 kHz, a voltage effective value of 7 kV, an output of 250 W, and oxygen of 5 liters per minute. The amount of ozone generated is 15 g / hr as a raw material.

  Although the discharge tubes are of the same scale, the present invention uses a power supply with an electric output of 500 W, whereas the electric output is increased in the case of inner water cooling and outer air cooling described in JP-A-2004-269326. The reason why the power is set to 250 W is that the water between the first quartz tube and the second quartz tube may start boiling when the output is further increased. In this respect, in the case of double-sided water cooling according to the present invention, boiling does not occur even when 500 W is set, and therefore, a higher ozone generation amount can be obtained.

  The present invention has two forms depending on whether the cooling water between the outer quartz tube 1 and the intermediate quartz tube 2 or the cooling water inside the inner quartz tube 3 is loaded with a high voltage.

  A case where a high voltage is applied to the cooling water inside the inner discharge tube is referred to as a first embodiment, and a case where a high voltage is applied to the cooling water between the outer quartz tube 1 and the intermediate quartz tube 2 is referred to as a second embodiment. Forms 1 and 2 show forms related to Claims 1 and 2 of the present invention, respectively. In the following description, the outer discharge tube 1, the intermediate discharge tube 2, and the inner discharge tube 3 are referred to as a first discharge tube 1, a second discharge tube 2, and a third discharge tube 3, respectively.

Form 1 (form relating to claim 1): An embodiment of the present invention will be described with reference to FIG.
Structure in Embodiment 1: First provided with three quartz tubes (1, 2, 3: hereinafter referred to as a first quartz tube, a second quartz tube, and a third quartz tube) arranged in common with the central axis The quartz tube 1 is welded to the surface of the second quartz tube 2 at both ends 4a and 4b.
The second quartz tube 2 is welded to the surface of the third quartz tube 3 at both end portions 5a and 5b.

A solid electric conductor 15 such as a stainless steel wire is introduced into the gap between the first quartz tube 1 and the second quartz tube, and the solid electric conductor 15 is connected to the ground side terminal 22 of the AC high voltage power supply 24. Yes.
A solid electric conductor 14 such as stainless steel is introduced into the third quartz tube 3, and the solid electric conductor 14 is connected to the high voltage side terminal 23 of the AC high voltage power supply 24.

An inlet 11 and an outlet 12 for cooling water are provided near both ends of the first quartz tube 1.
In the vicinity of both ends of the second quartz tube 2, an ozone generation source gas inlet 7 and an ozone-containing gas outlet 8 are provided.

Insulating pipes 20 and 21 for introducing and discharging cooling water into and out of the third quartz tube are connected near both ends of the third quartz tube 3.
The cross-sectional area and the length of the pipe are selected so that the electrical resistance between both ends of the pipe when the pipe is filled with cooling water is 1 MΩ or more.

  In the examples, fluororesin piping having an outer diameter of 4 mm, an inner diameter of 2 mm, and a length of 500 mm is used, and when tap water is used as cooling water, an electric resistance of 5 MΩ or more is obtained.

Method of use in embodiment 1: Cooling water is introduced into the gap 6 between the first quartz tube 1 and the second quartz tube 2 from the inlet 11 of the cooling water, and the cooling water is discharged from the outlet 12 of the cooling water.
Cooling water is introduced into the third quartz tube through one of the insulating pipes 20 and discharged through the other pipe 21.

The ozone generating source gas is introduced into the gap 25 between the second quartz tube 2 and the third quartz tube 3 from the inlet 7 of the ozone generating source gas.
By activating the AC high voltage power supply 24, an AC high voltage is applied between the solid electrical conductor 15 in the gap between the first quartz tube 1 and the second quartz tube 2 and the solid electrical conductor 14 inside the third quartz tube. By applying the load, a discharge is generated in the raw material gas for ozone generation between the second quartz tube 2 and the third quartz tube 3 to generate ozone, and the ozone-containing gas is taken out from the ozone-containing gas outlet 8 to the outside.

Embodiment 2 (Embodiment 2): An embodiment of the present invention will be described with reference to FIG.
Structure in form 2: The difference from the structure in form 1 is that an insulating pipe 20 for introducing and discharging cooling water into and between the first quartz tube 1 and the second quartz tube 2 in the vicinity of both ends of the first quartz tube 1; 21 is connected, and the cooling water inlet 9 and outlet 10 are provided in the vicinity of both ends of the third quartz tube 1. This is because the connection between the high-voltage side terminal of the AC high-voltage power supply and the discharge tube of the ground-side terminal is reversed from that in the first mode.
Other points are the same as in the first embodiment.

  Method of use in Form 2: Except for points based on structural differences from Form 1 above, the method of use is the same as in Form 1.

Additional explanation regarding the form of the invention: Reason why the electrical resistance when the insulating pipe is filled with cooling water is 1 MΩ or more The problem with the discharge tube of the present invention is that the pipe for guiding the cooling water to the high voltage side of the discharge tube This is a power loss at 20 and 21. The power loss WP in the two pipes is evaluated by the following (Equation 1).
WP = 2 × V × V / R (Formula 1)
Where V is the effective voltage value of the high voltage, R is the electrical resistance in a state where one pipe is filled with cooling water, and the coefficient 2 is doubled because there are two pipes on the supply side and the discharge side. Meaning.

From a practical point of view, the maximum loss of the above two pipe portions is allowed up to one third of the total output.
That is, WP = WT / 3 (Formula 2)
Here, WT is the total output.

From the above (Formula 1) and (Formula 2), the following formula is derived.
R = 6 × V × V / WT (Formula 3)

Here, when V = 9000V and WT = 500W, R = 972000Ω, which is almost 1MΩ.
In the first and second aspects, the reason why the upper limit of the electrical resistance when the pipe portion is filled with cooling water is 1 MΩ is based on such evaluation.

Naturally, when the total output WT is larger than 500 W, R evaluated by (Equation 3) also becomes large. For example, if WT = 1000 W, R is approximately 500 kΩ.
However, it is relatively easy to set the electrical resistance in the piping to about 1 MΩ. In the example using cooling water, 1 MΩ or more is obtained with a pipe having an inner diameter of 2 mm and a length of 100 mm. If the inner diameter is 4 mm, a length of 400 mm and 1 MΩ or more can be obtained.
Since it is not desirable to use with a resistance of 1 MΩ or less regardless of the magnitude of the total output from the viewpoint of energy saving, in the claims of the present invention, the upper limit of the electrical resistance when the piping is filled with cooling water is set to 1 MΩ. Was set.

  In the above-described embodiment, the electrical resistance of the pipe portion is 5 MΩ or more, the effective voltage effective value of high voltage is 9 kV, the power loss is 16 W or less for one pipe, and it is evaluated that two are 32 W or less. This means that the loss is 7% or less of the total output 500W.

  By using the discharge tube for generating ozone according to the present invention, an ozone generator capable of generating high-purity ozone can be configured because the ozone generation amount is compact and the ozone generation amount is high, and the gas contact part is only quartz. Such an ozone generator can be used in various fields such as semiconductor manufacturing, semiconductor cleaning, clean water sterilization, waste water treatment, pond water purification and the like.

The structure of the discharge tube of the triple tube structure concerning the form 1 (Claim 1) is shown. The structure of the discharge tube of the triple tube structure concerning form 2 (Claim 2) is shown.

1 First quartz tube (outer quartz tube)
2 Second quartz tube (intermediate quartz tube)
3 Third quartz tube (inner quartz tube)
4a quartz tube welded portion 4b quartz tube welded portion 5a quartz tube welded portion 5b quartz tube welded portion 6 gap between first quartz tube and second quartz tube 7 raw material gas inlet for ozone generation 8 ozone-containing gas outlet 9 cooling water inlet DESCRIPTION OF SYMBOLS 10 Cooling water outlet 11 Cooling water inlet 12 Cooling water outlet 13 Inside of the third quartz tube 14 Solid electric conductor 15 Solid electric conductor 16 L-type joint 17 Tee-type joint 18 Tee-type joint 19 L-type joint 20 Electrical insulating piping 21 Electrical Insulating Piping 22 Ground Side Terminal 23 High Voltage Side Terminal 24 AC High Voltage Power Supply 25 Gap between Second and Third Quartz Tubes

Claims (2)

A discharge tube for a silent discharge type ozone generator that generates ozone by applying an alternating high voltage to a gap, and has the following structures (a) to (h), and uses (i) to (l): Ozone generating discharge tube that generates ozone by means of
(A) Three quartz tubes (1, 2, 3, which are hereinafter referred to as a first quartz tube, a second quartz tube, and a third quartz tube from the outside) arranged to share the central axis are provided.
(B) The first quartz tube 1 is welded to the surface of the second quartz tube 2 at both ends 4a and 4b.
(C) The second quartz tube 2 is welded to the surface of the third quartz tube 3 at both ends 5a and 5b.
(D) A solid electric conductor 15 such as a stainless steel wire is introduced into the gap between the first quartz tube 1 and the second quartz tube, and the solid electric conductor 15 is connected to the ground side terminal 22 of the AC high voltage power supply 24. It is connected.
(E) A solid electric conductor 14 such as stainless steel is introduced into the third quartz tube 3, and the solid electric conductor 14 is connected to a high voltage side terminal 23 of an AC high voltage power supply 24.
(F) An inlet 11 and an outlet 12 for cooling water are provided near both ends of the first quartz tube 1.
(G) An ozone generating raw material gas inlet 7 and an ozone-containing gas outlet 8 are provided near both ends of the second quartz tube 2.
(H) Electrically insulating pipes 20 and 21 for introducing and discharging cooling water to and from the inside 13 of the third quartz tube 3 are connected near both ends of the third quartz tube 3.
Here, the cross-sectional areas and the lengths of the flow paths of these pipes are selected so that the electrical resistance between both ends of the pipes when the flow path is filled with cooling water is 1 MΩ or more.
(I) Cooling water is introduced into the gap 6 between the first quartz tube 1 and the second quartz tube 2 from the cooling water inlet 11 of (f), and the cooling water is discharged from the cooling water outlet 12.
(J) Cooling water is introduced into the third quartz tube through one of the electrically insulating pipes (h) and discharged through the other pipe 21.
(K) The ozone generating source gas is introduced into the gap 25 between the second quartz tube 2 and the third quartz tube 3 from the inlet 7 of the ozone generating source gas in (g).
(L) By activating the AC high-voltage power supply 24, the AC quartz is loaded between the solid electrical conductor 15 of (d) and the solid electrical conductor 14 of (e), and the second quartz tube A discharge is generated in the raw material gas for ozone generation between the third quartz tubes to generate ozone, and the ozone-containing gas is taken out from the ozone-containing gas outlet 8 to the outside. A discharge tube for a silent discharge type ozone generator that generates ozone by applying an alternating high voltage to a gap, and has the following structures (a) to (h), and uses (i) to (l): Ozone generating discharge tube that generates ozone by means of
(A) Three quartz tubes (1, 2, 3, which are hereinafter referred to as a first quartz tube, a second quartz tube, and a third quartz tube from the outside) arranged to share the central axis are provided.
(B) The first quartz tube 1 is welded to the surface of the second quartz tube 2 at both ends 4a and 4b.
(C) The second quartz tube 2 is welded to the surface of the third quartz tube 3 at both ends 5a and 5b.
(D) A solid electric conductor 15 such as a stainless steel wire is introduced into the gap between the first quartz tube 1 and the second quartz tube, and the solid electric conductor 15 is connected to the high voltage side terminal 23 of the AC high voltage power supply 24. It is connected to the.
(E) A solid electric conductor 14 such as stainless steel is introduced into the third quartz tube 3, and the solid electric conductor 14 is connected to the ground side terminal 22 of the AC high voltage power supply 24.
(F) Near the both ends of the first quartz tube 1, electrically insulating pipes 20 and 21 for introducing and discharging cooling water into and between the first quartz tube 1 and the second quartz tube 2 are connected.
Here, the cross-sectional areas and the lengths of the flow paths of these pipes are selected so that the electrical resistance between both ends of the pipes when the flow path is filled with cooling water is 1 MΩ or more.
(G) An ozone generating raw material gas inlet 7 and an ozone-containing gas outlet 8 are provided near both ends of the second quartz tube 2.
(H) In the vicinity of both ends of the third quartz tube 1, an inlet 9 and an outlet 10 for cooling water are provided.
(I) Cooling water is introduced into the gap 6 between the first quartz tube 1 and the second quartz tube 2 through one of the electrically insulating pipes (f) and discharged through the other pipe 21.
(J) Cooling water is introduced into the third quartz tube from the cooling water inlet 9 of (h), and the cooling water is discharged from the cooling water outlet 10.
(K) The ozone generating source gas is introduced into the gap 25 between the second quartz tube 2 and the third quartz tube 3 from the inlet 7 of the ozone generating source gas in (g).
(L) By activating the AC high voltage power source 24, an AC high voltage is applied between the solid electrical conductor (d) and the solid electrical conductor (e), and the second quartz tube and the third A discharge is generated in the raw material gas for ozone generation between the quartz tubes to generate ozone, and the ozone-containing gas is taken out from the ozone-containing gas outlet 8.

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