JP2002126769A - Ozone water treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the water or gas piping of an ozone water treatment apparatus, to prevent the loss of ozone by ozone gas piping and to enhance the cooling efficiency of a discharge space by cooling water to prevent the lowering of ozone forming efficiency caused by the generation of heat. SOLUTION: A high voltage electrode is placed at the central part in a porous pipe to form a gas passage between the porous pipe and the high voltage power electrode and an earth electrode is placed on the outside of the porous pipe and a passage of water to be treated is formed to the porous pipe in a direct contact state and a high voltage high frequency power supply or a high voltage pulse power supply is connected across the high voltage electrode and the earth electrode to form ozone in the gas passage to supply ozone gas to water to be treated in a fine bubble state through a dielectric.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone treatment apparatus and an ozone water producing apparatus for performing water treatment by injecting ozone gas into water to be treated.

[0002]

2. Description of the Related Art Conventionally, ozone gas is produced by a discharge-type ozonizer, and the ozone gas is mixed and brought into contact with water to be treated in a gas-liquid mixing section such as a bubbler, an ejector, a static mixer, etc., thereby producing ozone water and treating water. I was going. In many cases, water is separately supplied to the discharge-type ozonizer to cool the discharge-type ozonizer, so that the water piping becomes complicated and the device becomes large.

[0003] In the water cooling of the discharge type ozonizer,
In both the silent discharge ozonizer and the creepage discharge ozonizer, the gas passage, which is the discharge space, is cooled through the dense dielectric, which is hindered by the thermal resistance of the dielectric and can sufficiently cool the discharge space. No, the ozone generation efficiency is reduced.

[0004] Furthermore, the concentration of ozone generated by the ozonizer may decrease in the pipe between the ozonizer and the gas-liquid mixing section.

[0005]

The problem to be solved by the present invention is to simplify the water piping by using the water to be treated as it is as the cooling water for the discharge type ozonizer, and to improve the cooling efficiency of the discharge space. , Mixing high-concentration ozone immediately after generation with water without loss in the piping on the way
It is to provide a means for dissolution.

[0006]

In order to solve the above problems, in the ozone water treatment apparatus of the present invention, a high voltage electrode is placed at the center of the inside of the porous dielectric pipe, and the porous dielectric pipe and the high voltage electrode are connected to each other. A gas path is formed between the high-voltage electrode and the ground electrode, and a ground electrode is placed outside the porous dielectric pipe, and a water path to be treated is formed directly on the porous dielectric pipe. By connecting a high-voltage high-frequency power supply or a high-voltage pulse power supply therebetween, ozone is generated in the gas passage, and the ozone gas is supplied in a fine bubble state to the water to be treated through the porous dielectric.

In this case, as the porous dielectric pipe,
A porous ceramic pipe is most suitable, but a fluorine pipe having ozone resistance may be used. Further, a porous metal pipe such as a sintered porous stainless steel body may be used instead of the porous dielectric pipe.

In any case, the treated water (cooling water) and the gas passage (discharge space) are in contact with each other via a porous pipe, and if the gas pressure is kept higher than the water pressure, the water does not enter the discharge space. Thus, the discharge space can be effectively cooled. Furthermore, by appropriately setting the pore diameter and wall thickness, the gas pressure and the water pressure of the porous pipe, the gas-liquid mixing ratio (the ratio of ozone gas injected into the treated water to water) can be kept optimal.

In this case, even if the gas pressure is kept higher than the water pressure, water tends to enter the inside of the porous pipe due to the capillary phenomenon in the porous pipe. On the other hand, the gas passes through the porous pipe and comes out as fine bubbles in the treated water. As a result, the porous pipe is cooled by both water and gas, and there is no risk of heating the discharge space.

[0010] Further, the ozone gas is supplied to the treated water as it is through the porous pipe forming the ozone generating space (discharge space, gas passage) without any intermediate piping,
A decrease in ozone concentration between the ozone generation space and the mixing section can also be prevented.

As a result, according to the present invention, since the cooling water pipe and the treated water pipe become one and there is no need to separately provide an ozone gas outlet, the labor and cost of the pipe can be greatly reduced.

Further, depending on the quality of water used to cool a dense dielectric with a conventional ozonizer, organic substances and microorganisms in the cooling water may form a film on the dielectric surface and hinder thermal contact between the cooling water and the dielectric. However, in the ozone water treatment apparatus according to the present invention, since the ozone is always supplied to the porous pipe of the heat exchange section, the heat exchange section is always maintained normally by the sterilization of ozone and the action of decomposing organic substances, so that the heat exchange efficiency is improved. There is also a side effect of not causing a decrease.

According to the present invention, a discharge is caused in a gas passage formed between the high-voltage electrode placed at the center of the inside of the porous pipe and the porous pipe. When a porous dielectric pipe is used, discharge occurs even in pores inside the porous dielectric pipe, but it is necessary to maintain stable discharge that does not shift to arc discharge in any case. Therefore, it is preferable to use a pulse power supply that generates a steep pulse having a pulse width of 1 μs or less as a power supply. When a pulsed high voltage is applied between the high-voltage electrode and the ground electrode or porous metal pipe formed outside the porous dielectric pipe, a sufficiently strong discharge occurs, but the voltage value is sufficient before the transition to arc discharge. It is possible to maintain a stable discharge due to the decrease.

When a porous dielectric pipe is used, it is necessary to place a ground electrode outside the pipe, but since the treated water of low resistance covers the outer surface of the porous dielectric pipe, the entire outer surface has substantially the same potential. You can think that it will be. In addition, the porous dielectric pipe accumulates charges by pulse discharge, but again, the treated water enters the porous body by capillary action, so that the charges that are going to accumulate are quickly alleviated. There is no charge accumulation for each pulse application. as a result,
Even if the pulse application frequency is increased, a sufficiently large electric field is formed in the gas passage, and a strong discharge is generated every time the pulse is applied.

On the other hand, when a high-frequency high-voltage power supply (AC power supply) is used as the power supply, a high-voltage electrode provided at the center of the inside of the porous pipe is preferably covered with a dense dielectric. Even if the high-frequency discharge attempts to shift to the arc, the dielectric covering the high-voltage electrode serves as a barrier, and the shift of the arc can be prevented. Of course, even when a pulsed power supply is used, more stable discharge can be expected by coating the dielectric, but the dielectric coating may not be required because the structure becomes complicated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings.

[0016]

FIG. 1 shows an ozone water treatment apparatus according to a first embodiment of the present invention. A high voltage electrode 25 is formed at the center of the inside of a porous dielectric pipe 23a formed of alumina ceramic or the like.
Is arranged. A ground electrode 24 formed in a mesh shape, a spiral shape, a ring shape, or the like is placed in contact with or in proximity to the porous dielectric pipe 23a.

The high voltage electrode 25 is connected to a bushing 35, and the ground electrode 24 is connected to a power supply 33 via a current introduction terminal 31. As the power supply 33, a high-voltage pulse power supply or a high-frequency high-voltage power supply is used. In particular, when a high-frequency high-voltage power supply is used, the high-voltage electrode 25 is preferably covered with a dense dielectric 26.

Air or oxygen gas serving as a source of ozone is supplied from a source gas inlet 11 to a gas passage (discharge space) 13 formed between the porous dielectric pipe 23a and the high-voltage electrode 25. When a high-voltage pulse power supply or a high-frequency high-voltage power supply is operated, discharge occurs in the gas passage (discharge space) 13 and the pores inside the porous dielectric pipe 23a. This discharge generates low-temperature plasma in which the electron temperature is high but the temperature of ions and neutral molecules is low. In low-temperature plasma, oxygen molecules are efficiently dissociated to generate oxygen atoms. Oxygen is generated by three collisions of oxygen atoms with oxygen molecules.

On the other hand, the water to be treated is discharged from the water inlet 10 through the water passage 12 formed between the porous dielectric pipe 23a and the container 21 from the water inlet 10. The ozone gas generated in the gas passage (discharge space) 13 while passing through the water passage 12 passes through the porous dielectric pipe 23a, becomes fine bubbles in the water passage 12, and is mixed with the water to be treated. .

As a result, the organic matter in the water to be treated, CO
D, BOD, etc. are decomposed by ozone. Also,
When the water to be treated is clean water, ozone water is supplied to the water outlet 14.
Is discharged from

Of the energy injected by the discharge into the gas passage (discharge space) 13 and the inside of the porous dielectric pipe 23a, only 20% is used for generating ozone, and the rest becomes heat. When heat accumulates, and particularly when the temperature of the porous dielectric pipe 23a becomes high, the ozone generation efficiency is greatly reduced. That is, the ozone synthesis reaction due to the three-body collision is inhibited by heat, and the generated ozone is thermally decomposed while passing through the porous dielectric pipe 23a.

Since the water to be treated passing through the water passage 12 is in direct contact with the porous dielectric pipe 23a, the porous dielectric pipe 23a can be cooled. Porous pipes inherently have poor thermal conductivity due to the large number of gas pores. However, when water is injected into the porous dielectric pipe 23a,
The cooling is relatively effective because the cooling is performed in direct contact with the cooling water. Further, water tends to enter the porous dielectric pipe 23a by capillary force. On the other hand, ozone gas also tends to pass through the porous dielectric pipe 23a, so that a gas-liquid interface is formed inside the porous dielectric pipe 23a,
The thermal conductivity of the porous pipe is also improved and cooling is efficient.

When a pulse high voltage power supply is used as the power supply 33, the pulse width is 1 μs or less, preferably 500 ns.
By changing the discharge to arc discharge,
It is necessary to prevent the dielectric breakdown of the porous dielectric pipe 23a.

In this case, covering the high-voltage electrode 25 with a dense dielectric 26 is also effective as an arc discharge prevention measure. In particular, when a high-frequency high-voltage power supply is used as the power supply 33, the dielectric 26 is indispensable. That is, since the high-frequency discharge easily shifts to an arc without the dielectric 26, it can be considered to be equivalent to the dielectric barrier of the silent discharge method.

As the ground electrode 24, the porous dielectric pipe 2
An electrode is provided near the outer periphery of 3a so that gas or water formed in a net shape, a spiral shape, a ring shape, or the like can easily pass therethrough. Water directly contacts the ground electrode 24 and the outer periphery of the porous dielectric pipe. Apart from the case of using pure water, it can be considered that the outer periphery of the porous dielectric pipe is kept at the ground potential because water is conductive.

When a pulsed high voltage power supply is used, a positive polarity pulse is usually applied, but positive ions are accumulated on the inner surface of the porous dielectric pipe by pulse discharge. Normally, the charge relaxation time τ is 1 / (product of the resistivity σ of the dielectric pipe and the dielectric constant ε).
It is proportional to the square. However, water has penetrated into the outer surface of the porous dielectric pipe and the inside of the pipe by capillary force, and σ
Is greatly reduced, so that the ions accumulated on the inner surface of the pipe are quickly alleviated. As a result, an electric field due to charges that should accumulate every time a pulse is applied is not generated, and the intensity of the electric field formed in the gas passage (discharge space) 13 by the pulse application can be kept large.

FIG. 2 shows a case where a porous metal pipe 23b is used instead of the porous dielectric pipe 23a of FIG.
In this case, the ground electrode is the porous metal pipe 23b itself. Other principles are exactly the same as in FIG.

FIG. 3 shows an example in which the ozone water treatment apparatus 1 according to the present invention is connected to a water treatment system. A source gas source 41 such as dry air or oxygen and water to be treated are connected to the ozone water treatment apparatus 1 by pipes 43 and 46 by a pump 45.

The water to be treated mixed with the ozone gas in the ozone water treatment apparatus 1 is promoted by the static mixer 47 to mix and dissolve the ozone gas, and is introduced from the lower part of the treatment tank 48. In the processing tank 48, gas-liquid separation is performed, and gas that has not been dissolved in the water to be processed, particularly residual ozone gas, is separated. Residual ozone gas is checked valve 49
Then, it is decomposed into oxygen by the ozone killer 50 and released to the outside.

In the processing tank 48, the undissolved ozone gas rises as bubbles and further dissolution proceeds. Although not shown in the processing tank 48, an oxidation promoting method using a hydrogen peroxide solution, an ultraviolet lamp, or the like may be used. The water purified as a result of the ozone treatment is discharged from the water outlet 51. Further, the water outlet 51 of the mixing tank 48 may be led to an activated carbon layer or an activated sludge tank to construct a water treatment system.

FIG. 3 shows an example in which the present ozone water treatment apparatus is incorporated in a water treatment system. The system configuration can be freely changed according to the properties and amount of water to be treated and the desired cleanliness. It goes without saying that you can do it.

Of course, it is also possible to aim at obtaining high concentration ozone water with the water to be treated being clean water. It is also possible to omit the static mixer 47, the processing tank 48, and the ozone killer 50 depending on the ozone water concentration and the excess ozone gas concentration.

In FIG. 3, the source gas pressure Pg and the pressure Pw of the water to be treated need to be set so that Pg> Pw is always satisfied. That is, the porous dielectric pipe 23a in FIG. 1 and the porous metal pipe 23b in FIG.
The gas must always be set up to mix with the water through these. Conversely, water is a gas passage (discharge space)
When the intrusion occurs, the discharge becomes unstable and the ozone generation efficiency is greatly reduced.

Further, since the mixing ratio of water and ozone gas changes depending on the source gas pressure Pg and the pressure Pw of the water to be treated, it is desirable to finely control the pressure Pg of the source gas and the pressure Pw of the water to be treated. , Pw while controlling Pg such that the set pressure difference ΔP is always obtained, but the control circuit is omitted here.

[0035]

As described above, the ozone water treatment apparatus of the present invention supplies the ozone gas generated in the discharge space as fine bubbles to the water passage directly contacting through the porous pipe without direct piping. There is no ozone loss in the piping. Further, since the water to be treated directly cools the porous pipe as the cooling water for the ozone generating section, the cooling efficiency of the discharge space is increased, and a decrease in the ozone generating efficiency can be prevented. Also,
As a result, the piping of the ozone water treatment device can be greatly simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view of a configuration diagram of an ozone water treatment apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a configuration diagram of an ozone water treatment apparatus according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a water treatment system using the ozone water treatment apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 20 container flange (water inlet part) 22 container flange (water outlet part) 30 wiring 31 ground side wiring 32 high pressure side wiring 42 gas pressure sensor 43 gas pipe 44 water pressure sensor 45 pump 46 water pipe

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D050 AB06 AB07 BB02 BC10 BD03 BD04 BD06 CA06 4G035 AA01 AB26 AE13 4G042 CA01 CC16 CE01 4K021 AA09

Claims (3)

[Claims] In an ozone water treatment apparatus for injecting ozone gas into water to be treated, a high voltage electrode is placed in the center of the inside of a porous dielectric pipe, and a gas passage is provided between the porous dielectric pipe and the high voltage electrode. A ground electrode is placed outside of the porous dielectric pipe, and a water passage to be treated is formed directly on the porous dielectric pipe. An ozone water treatment apparatus characterized in that ozone is generated in the gas passage by connecting a high voltage pulse power supply, and ozone gas is supplied to the water to be treated in the form of fine bubbles through the porous dielectric. 2. An ozone water treatment apparatus for injecting ozone gas into water to be treated, wherein a high voltage electrode made of a dielectric is placed in the center of the inside of the porous metal pipe, and a gas passage is provided between the porous metal pipe and the coated high voltage electrode. Forming a passage for water to be treated directly on the porous metal pipe, and connecting a high-voltage high-frequency power supply or a high-voltage pulse power supply between these high-voltage electrodes and the porous metal pipe to form the gas passage. Wherein the ozone gas is supplied to the water to be treated in the form of fine bubbles through the porous metal pipe. 3. The ozone water treatment apparatus according to claim 1, wherein the high-voltage electrode is covered with a dielectric.