JP2965873B2 - Ultra-high purity electrolytic ozone generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic ozone generator, and is used in a field requiring extremely high-purity ozone gas, for example, in a cleaning process of precision parts in the electronics industry, especially a semiconductor integrated circuit.

[0002]

2. Description of the Related Art As an ozone generator, there are a general silent discharge type ozone generator and an electrolytic ozone generator for electrolyzing pure water using a solid polymer electrolyte membrane. In a silent discharge type ozonizer, since the electrode portion is in a plasma state at the time of discharge, the material forming the electrode is etched,
Since the components are mixed into the generated ozone gas, the purity of the ozone gas is considerably reduced. On the other hand, in an electrolytic ozone generator, the electrode is immersed in pure water or ultrapure water, and water is electrolyzed in a physicochemically calm state. Is mixed with impurities, but in reality, very small amounts of impurities mainly composed of metal are mixed.

[0003] On the other hand, there is an ozone application field in which impurities are not allowed to be mixed even in a very small amount, such as a cleaning step using ozone in a process of manufacturing a semiconductor integrated circuit. However, the conventional ozone generator cannot produce such extremely high-purity ozone.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art and solves the problem of impurities mainly containing iron and other metals.
It is an object of the present invention to provide an electrolytic ozone generator capable of producing ultra-high-purity ozone with almost completely removed ozone.

[0005]

In order to solve the above-mentioned problems, the present invention provides an electrolytic ozone generator, comprising: an electrolytic ozone generator for generating ozone gas; and a small amount of iron generated by the electrolytic ozone generator. Gas containing less than about 10 ° C
To a cooler for cooling, a mist separator for removing mist in the gas which has been cooled by the cooler, characterized by having the.

[0006]

The electrolytic ozone generator generally includes a main body in which an anode and a cathode are disposed with an ion exchange membrane such as a solid polymer electrolyte membrane interposed therebetween, and a gas-liquid separation tank for storing pure water and the like. While circulating pure water between the gas and the gas-liquid separation tank, oxygen generated by the electrolysis and a mixed gas consisting of ozone gas contained at a high concentration therein are separated from the pure water in the gas-liquid separation tank. It is configured to take out. When oxygen and ozone gas are separated in the tank, mist also jumps out of the water surface of the tank at the same time. Some of the mist may include a trace amount of impurities such as a metal containing eluted iron . Most of such mist is separated in the tank, but small amounts, especially fine mist, are entrained in the gas removed from the tank.

On the other hand, during electrolysis, the operating temperature of pure water is usually 3
The temperature rises from 5 ° C. to 40 ° C., and steam is generated in the gas-liquid separation tank. These gases are cooled to below about 10 ° C. in the electronic cooler , a component of the present invention. Steam, so has become saturated at the operating temperature, it is cooled by the majority example up to 5 ° C. to condense. Since the condensation is carried out using the mist accompanying the gas as a nucleus, the size of the mist is increased. Those in contact with the larger ones and cooling unit of the cooler particle size in the mist is removed by the cooler. Thereby, a considerable amount of impurities is also removed.

In the present invention, since a mist separator is further provided, mist not removed by the cooling means is captured and removed by the mist separator. In this case, since the water vapor is liquefied by cooling and adheres to the mist, and the mist has a large diameter, the mist is almost completely removed by the mist separator very efficiently. Then, impurities are almost completely removed, and an ultra-high purity ozone gas can be obtained.

[0009]

FIG. 1 shows the overall structure of an electrolytic ozone generator according to an embodiment. The apparatus has an electrolytic ozone generator 1 for generating ozone gas, an electronic cooler 2 for cooling the generated gas, and a mist separator 3 for removing mist in the cooled gas.

As shown in FIG. 2, the electrolytic ozone generating section 1 is provided with an anode 13 and a cathode 14 between an anode plate 11 and a cathode plate 12 and a solid polymer electrolyte membrane 15 separating them. It comprises an electrolysis cell 16 and a gas-liquid separation tank 17 storing pure water. or,
Reference numerals 18 and 19 are a pure water inlet and an outlet, respectively. DC power is supplied to the anode plate 11 and the cathode plate 12 from a power supply device (not shown).

The electronic cooler 2 using a Peltier element has a main body 21, a cooling chamber 22, and cooling fins 23 extending from the main body into the cooling chamber. Although not shown, a thermoelectric element, a cooling fan, a radiating fin, and the like are built in the main body 21. The radiating fin contacts the high-temperature side of the thermoelectric element, and the cooling fin 23 contacts the low-temperature side. Power is supplied directly from the power supply. The radiating fins are air-cooled by a fan, and emit the heat absorbed by the cooling fins 23. In this apparatus, the passing gas can be cooled to about 10 ° C. or less.

As the mist separator 3, various types and structures can be used. In the present embodiment, a filling type separator 31 in which a layer 31b made of long quartz fibers is filled in a casing 31a, and a pore size made of PTFE. 0.05
An apparatus combined with a membrane filter 32 of about μm is used.

When the apparatus is operated by supplying pure water as raw water to the electrolytic ozone generator 1, the pure water is supplied from a pure water inlet 18 of the electrolytic cell 16, while passing through the anode plate 13. A part is electrolyzed into oxygen, hydrogen and ozone gas, and oxygen and ozone gas are taken out together with circulating water from the pure water outlet 19 on the anode side, and these gases are separated in the gas-liquid separation tank 17 and taken out from the outlet pipe 17a. . In this gas, the ozone gas has a high concentration of about 10 to 15% by weight.

When the generated gas is separated from the water,
As shown in the figure, the water surface of the tank rises and bursts, and the mist jumps out together with the gas. The mist also contains impurities present in trace amounts in pure water. Most of the mist is in tank 17
Although it is dropped and adheres to a peripheral wall surface and removed, a part of the gas leaves the tank 17 accompanying the gas.

On the other hand, when the ozone generating section is in the operating state, the pure water circulating is 35 ° C. to 40 ° C.
C, and the vapor-liquid separation tank 17 is filled with evaporated pure water vapor.
Go out of.

When the generated gas with mist and water vapor enters the cooling chamber 22 of the cooler 2, the cooling fins 23 cool the gas to, for example, about 5 ° C., and the water vapor drops to a temperature considerably lower than the dew point. A considerable amount of water vapor is condensed with the mist as nuclei, comes into contact with the cooling fins or drops as large water drops into the cooling chamber, and is discharged from the drain pipe 22a. If impurities are mixed in the mist, they are also discharged.

Of the water droplets that have become large with the mist as nuclei, those having a small diameter pass through the cooling chamber together with the generated gas and pass through the separator 31 of the mist separator 3 and the membrane filter 32. During this time, the mist comes into contact with the filler or the filter element having a large contact area, is captured, and is discharged as water droplets. In this case, since the size of the mist is increased by cooling, almost all of the mist in the generated gas is almost completely removed. As a result, there is almost no impurity, and an ultra-high purity ozone gas is produced.

According to the experiments conducted by the inventors, a gas containing ozone gas at a high concentration was supplied at a flow rate of 185 ml in the electrolytic ozone generator 1.
/ Mim, cooled to 5 ° C. by the cooler 2 and passed through the mist separator 3. The outlet position A of the ozone gas generator 1, the outlet position B of the cooler 2 and the outlet position of the mist separator 3 shown in FIG. A mixed gas was sampled from C, and the results of measuring the impurity concentrations thereof were as follows. Sample position Iron concentration in ozone gas (ng / L) A5B0.47C0.02

As described above, iron as a representative of impurities is
First, a considerable amount was removed by the cooler 2 and captured by the mist separator 3 when passing through the mist separator 3. Therefore, all impurities including iron are also almost completely removed at such a ratio.

[0020]

As described above, according to the present invention, the electrolytic ozone generator, the electronic cooler, and the mist separator are provided to prevent the temperature of pure water from rising and the generation of water vapor during the operation of the ozone generator. Using an electronic cooler, the generated gas accompanied by water vapor is once cooled to a temperature lower than approximately 10 ° C. , and the water vapor is condensed by using the mist containing impurities as a nucleus to expand the mist size, and then passed through a mist separator. As a result, it has become possible to remove impurities including trace amounts of iron contained in ozone gas, which has been difficult in the past. As a result, extremely high-purity ozone gas from which impurities have been almost completely removed can be produced. And like this
Ozone gas from which metal such as iron has been almost completely removed, so that contamination of metal impurities is not allowed even in a very small amount.
It can be conveniently used for cleaning components in the precision electronics industry, which is a field of ozone utilization . Further, the use of ozone can be expanded.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the overall configuration of an electrolytic ozone generator according to an embodiment.

FIG. 2 is an explanatory diagram showing a structure of an electrolytic ozone generating section of the above device.

[Explanation of symbols]

1 electrolytic ozone generator 2 electronic cooler 3 mist separator

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C25B 1/00-15/08

Claims (1)

(57) [Claims] 1. An electrolytic ozone generator for generating ozone gas
Generated in the raw part and the electrolytic ozone generatorContains trace amounts of iron
GasAt a temperature below about 10 ° CCoolingElectronic cooler
And theElectronic coolerRemoves mist in the gas cooled by
And a mist separator.
Type ozone generator.