JPH10213293A - Ozone gas concentration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enrich ozone in a high density by reducing the pressure in a storing vessel after selecting, adsorbing and saturating the ozone to a silica gel in the storing vessel. SOLUTION: A storing vessel 1 filled with silica gel 2 as an adsorbent inside is stored in an outer box 3 formed of a heat insulating box and cooled to approx. -78 deg.C by dry ice 4 stored in the outer box 3. After ozonizing oxygen gas introduced from the raw material oxygen supply source 11 of an oxygen cylinder by an ozone generator 9, the mixing gas of ozone-oxygen is produced and controlled to a certain flow rate by a flow rate controller 10 and supplied to the storing vessel 1 through an ozone supply route 5. Here, after adsorbing and saturating the ozone to the silica gel 2, by reducing the pressure in the storing vessel 1 upto the pressure of the partial pressure or less of the supplied ozone, oxygen is separated and discharged from the silica gel 2 preferentially and the ozone density in the storing vessel 1 is enriched. The enriched ozone is taken out by increasing the temperature of the storing vessel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for concentrating ozone gas.

[0002]

2. Description of the Related Art It has been considered that ozone gas cannot be stored as ozone gas because of its strong self-decomposition property. Therefore, conventionally, an ozone gas is generated by an ozone generator in the vicinity of a place where ozone is used, and the ozone gas is used immediately. However, in this case, the concentration of the ozone gas generated by the ozone generator was about 5 to 7 vol%, and the ozone concentration was low. Therefore, a technique has been provided in which ozone gas is adsorbed on silica gel to concentrate the ozone gas.

[0003]

In the conventional ozone enrichment method, about 5 to 7 vol% of ozone gas generated by an ozone generator is filled with silica gel and dried at a low ice temperature.
(−78 ° C.) is supplied into a storage container cooled to (−78 ° C.), and ozone is concentrated by selectively saturating and adsorbing ozone on silica gel. Because of the adsorption, ozone could only be concentrated up to about 70 vol%. The present invention has been made in view of such a point,
It is an object of the present invention to provide a method for concentrating ozone gas which can be concentrated to a higher concentration.

[0004]

In order to achieve the above-mentioned object, the present invention is characterized in that ozone is selected and adsorbed on silica gel in a storage container, and then the pressure in the storage container is reduced. And

[0005]

According to the present invention, after the ozone gas is selectively adsorbed and saturated on the silica gel in the storage container, the pressure in the storage container is reduced. Since silica gel adsorbs more ozone gas than oxygen in the low temperature range, oxygen and ozone gas are present in the silica gel at an ozone-rich partial pressure ratio, and oxygen and ozone gas are present in the gas phase at a partial pressure ratio proportional to the supply gas concentration. Will exist. When the storage container is evacuated to a reduced pressure, oxygen is selectively desorbed from the silica gel in an attempt to maintain the partial pressure ratio in the gas phase. For this reason, the ozone concentration of the adsorbed gas left on the silica gel increases, and the ozone concentration of the adsorbed gas finally reaches nearly 100%. Theoretically, this decompression operation may be performed at or below the supply ozone partial pressure during the adsorption operation.Here, when the pressure in the gas phase is reduced to a state lower than the supply ozone partial pressure, silica gel is used. Since the amount of desorbed ozone gas increases, the ozone storage amount will be lost. Therefore, it is desirable to set the pressure near the partial pressure of the supplied ozone.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. FIG. 1 shows a schematic diagram of an ozone filling device, and
(1) is a storage container filled with silica gel (2) as an adsorbent, and this storage container (1) is stored in an outer box (3) formed of an insulated box, and the storage container (1) is It is cooled to -78 ° C with snowy dry ice (4) stored in the outer box (3).

The storage container (1) has an ozone supply passage.
(5), an ozone lead-out path (6) and a relief path (7) are connected respectively, and an ozone generator is connected to the ozone supply path (5).
(9), a flow controller (10) is arranged in order, and oxygen gas derived from a raw material oxygen supply source (11) such as an oxygen cylinder is ozonized by an ozone generator (9), and an ozone-oxygen mixed gas is obtained. The ozone-oxygen mixed gas is controlled at a constant flow rate by the flow rate controller (10) and supplied to the storage container (1).

The relief path (7) is provided with a relief valve (12),
When the pressure in the storage container (1) rises above a set pressure, the relief valve (12) is activated and the ozone decomposed from the storage container (1) is discharged. Ozone gas in the oxygen mixed gas is decomposed by an ozone decomposer (14) and released to the atmosphere. In the figure, reference numeral (15) denotes an on-off valve arranged in the ozone outlet passage (6), (16) denotes a pressure indicator, and (1)
7) is a temperature indicator, (18) is a heater, and the on-off valve (15) is arranged in the outer box (3). In addition, this ozone derivation route
An ozone monitor circuit (19) is branched and derived from (6),
This ozone monitor circuit (19) has an ozone monitor (20)
And an ozone decomposer (21). This ozone decomposer
A vacuum pump (22) is branched and connected to an ozone monitor circuit (19) downstream of (21).

The silica gel to be filled in the storage container (1)
As for (2), impurities are removed from commercially available silica gel having a purity of 99.7% as much as possible, and the contained impurity components are 2.7 ppm by weight of aluminum, 0.9 ppm or less of titanium, and 2.7% by weight of iron. 9 ppm, calcium 0.
A high purity silica gel prepared by adjusting the purity to 7 ppm or less, 0.9 ppm or less for magnesium, 3 ppm or less for sodium, and 0.7 ppm or less for zirconium to high purity 99.99% is used. After removing water from the silica gel, the container is filled.

The ozone-oxygen mixed gas flowing into the storage container (1) is filled with silica gel (2) in the storage container (1).
And the ozone in the mixed gas is selectively adsorbed on the silica gel (2). At this time, the remaining oxygen gas is discharged from the ozone outlet path (6) in a non-adsorbed state. Ozone generator
The ozone in the ozone-oxygen mixed gas derived from (9) is about 5 vol%, but the ozone concentration increases to about 70 vol% by the selective adsorption of ozone by the silica gel (2).

After the ozone is saturated and adsorbed on the silica gel (2) at atmospheric pressure, the pressure in the storage vessel (1) is reduced to 38 Torr, which is the partial pressure of the supplied ozone. By this decompression operation, oxygen is preferentially desorbed from the silica gel (2) and discharged in an attempt to maintain the ozone-oxygen partial pressure ratio in the gas phase during the saturated adsorption. Ozone concentration is 100 vol% theoretically, at least 9 vol.
It is concentrated to 0 vol%. During the pressure reduction operation, the pressure inside the storage container is lower than the partial pressure of the supplied ozone (for example, 20T).
orr), the amount of ozone adsorbed on the silica gel is increased and the storage amount is lost.In this depressurization operation, the pressure in the storage container is higher than the ozone supply partial pressure. It is desirable to avoid low pressure.

The removal of the ozone adsorbed on the silica gel (2) is performed by changing the temperature at which the storage container (1) is cooled. That is, if the storage container (1) is heated by a heater or the like, or the refrigerating device is stopped to lower the cooling degree and raise the temperature, the ozone adsorption capacity of the silica gel (2) is reduced. Releases ozone. At this time, the ozone concentration taken out of the storage container (1) was 85 vol%. Here, it is considered that the reason why the concentration of the extracted ozone is reduced is that ozone is decomposed at the time of desorption to generate oxygen.

[0013]

According to the present invention, the ozone gas is selectively adsorbed and saturated on the silica gel in the storage container, and then the pressure in the storage container is reduced. The components are selectively desorbed, and the ozone component can be adsorbed and held on the silica gel at a high concentration. This makes it possible to use stable high-concentration ozone.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an ozone filling device.

FIG. 2 is a diagram showing a relationship between a concentration process and an ozone concentration.

[Explanation of symbols]

1. Ozone storage container 2. Silica gel 3. Outer box 4.
Dry ice, 9 ... Ozone generator.

Claims (2)

[Claims] An ozone gas generated by an ozone generator is supplied to a storage container filled with silica gel therein, and ozone is saturated and adsorbed on the silica gel in the storage container. A method of concentrating ozone in which the pressure inside is reduced. 2. The method for concentrating ozone according to claim 1, wherein the internal pressure in the storage vessel is reduced to a partial pressure of the supplied ozone or less.