JP2002087805A - Ozone generating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the maintenance of stable ozone concentration even in the long term operation by selecting the material of a gas duct piped between an oxygen equipment and an ozone generating device. SOLUTION: In the ozone generation device constituted so as to combine the oxygen equipment A with the silent discharge type ozone generating device B and to introduce high purity gaseous oxygen supplied from the oxygen equipment into the ozone generating device through the gas duct C, the gas duct C uses a pipe (a fluororesin pipe C-1) made of a non-metallic material such as a fluororesin, a vinyl resin, a polyamide based resin or one formed by coating the inside surface of a metallic pipe (a stainless steel pipe C-2) with a non-metallic material (a fluororesin C-3) and the decomposition of the generated zone due to the activated oxygen is suppressed by sending a trace quantity of gaseous nitrogen released from the gas duct with oxygen to the ozone generating device and reacting the activated oxygen generated in the ozone generating process by silent discharge with nitrogen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone generating apparatus for obtaining high-concentration ozone used for sewage treatment and pulp bleaching.

[0002]

2. Description of the Related Art Ozone generating equipment is used for sterilization and treatment of ozone.
It is widely used in water and sewage treatment facilities, pulp bleaching facilities, etc., utilizing the power of decolorization and deodorization. Next, a conventional ozone generation facility will be described with reference to FIGS. That is, as shown in the system diagram of FIG.
The oxygen facility A and the ozone generator B are combined, and a gas pipe C of a stainless steel pipe is provided between the two.

[0003] Here, the oxygen equipment A comprises a dewar bottle A-1 containing liquid oxygen and an evaporator A for vaporizing liquid oxygen.
-2, which converts liquefied oxygen into high-purity oxygen gas (usually 99.99%). Then, the high-purity oxygen gas (raw material gas) obtained in the oxygen facility A is sent to an ozone generator B through a gas conduit C, and is flowed through a discharge tube in the apparatus to generate ozone by silent discharge. As the oxygen equipment A, an oxygen cylinder A-3 may be connected to the gas conduit C as shown in the figure instead of the liquid oxygen equipment described above, and high-purity oxygen gas may be directly supplied from the oxygen cylinder A-3. .

Next, an example of an ozone generator is shown in FIG.
This is shown in (b). The ozone generator shown in the illustrated example has been proposed as Japanese Patent Application Laid-Open No. 9-315803 prior to the same applicant as the present invention. In the figure, reference numeral 1 denotes a main body of the ozone generator, the opening at both ends of which is closed by side plates 2 and 3 via a packing 17, and a raw material gas inlet 7 and an ozonized gas outlet on the peripheral surface. 8, and the cooling water inlet 9 and outlet 10 are open.

A pair of left and right partition plates 5 and 6 are provided inside the body 1 at intervals.
A large number of ozone generating tubes 11 are erected through the space. The ozone generating tube 11 has a cylindrical metal tube 11a as a ground electrode, a glass dielectric layer 11b formed by lining on the inner surface side of the metal tube 11a, and an inside of the ground electrode 11 including the dielectric layer 11b. And a cylindrical high voltage electrode 13 opposed to a discharge gap 12 having a substantially uniform gap length. The high voltage electrode 13 is externally connected via a lead wire 14 drawn out from its end and a bushing 15. Is connected to the high-frequency power supply 16 of FIG.

A water jacket 4 is provided between the ozone generating tube 11 and the partition plates 4 and 5 on the outer peripheral side of the metal tube 11a.
The cooling water (ion exchange water) is made to flow from the cooling water circulation line 19 through the cooling water inlet 9 and the outlet 10. For the high-voltage electrode 13, a water guide pipe 24 branching from a manifold 24 interposed in a cooling water circulation line 19 is connected to an electrode tube so that cooling water flows. In addition, 20 is a cooling water feed pump, 2
Reference numeral 1 denotes a heat exchanger for cooling with secondary cooling water. With this configuration, the source gas (oxygen gas) sent from the source gas inlet 8 is discharged from the discharge gap 1 through the opening end of the ozone generating tube 11.
2 and is ozonized and flows out of the gas outlet 8.

An exhaust valve (not shown) is mounted downstream of the gas outlet 8, and by adjusting the opening degree of the exhaust valve, the raw material gas containing oxygen in the body of the ozone generator is compressed to the pressure. Is, for example, 0.18MPa
It has been adjusted to a degree. With the oxygen gas adjusted to such a pressure flowing, a high-frequency power source 1 is connected between the metal tube (ground electrode) 11 a of the ozone generating tube 11 and the high-voltage electrode 13.
It is well known that when the high frequency voltage supplied from 6 is applied, a silent discharge is generated, and high-purity oxygen gas is ozonized to generate high-concentration ozone.

[0008]

By the way, in the above-mentioned conventional ozone generating equipment, the purity of the raw material gas is 99.9.
If the operation is continuously performed for a long time using the oxygen gas obtained by evaporating the liquid oxygen at the 9% level, there is a problem that the concentration of ozone generated by the ozone generator gradually decreases as the operation time elapses. This phenomenon appears remarkably when the oxygen purity of the source gas increases. Moreover, if the ozone concentration decreases during the operation of the ozone generating equipment, the ozone sterilization,
The ability to decolorize and deodorize is weakened, which impairs water and sewage treatment and pulp bleaching at the destination.

[0009] Then, when the inventors investigated the cause of the above phenomenon, it was found that the following was involved in the cause. That is, when generating the ozone silent discharge method, (O ₂ ^* of the formula (1), O ^* of the formula (2)) the following equation (1) to highly reactive active oxygen as indicated by (3) occurs . O ₂ + e → e + O ₂ ^* ... (1) O ₂ ^* + e → e + O + O ^* ... (2) O + O ₂ + M → O ₃ + M ... … (3)

When the ozone generator is operated continuously for a long time, the active oxygen is adsorbed on the electrode surface, and the active oxygen reacts with ozone generated by the discharge. As a result, as shown by the following equations (4) to (6), ozone is decomposed into oxygen molecules or oxygen atoms, which lowers the concentration of ozone extracted from the ozone generator. ^{_{O 3 + O 2 * → O}} + 2O 2 ............ (4) O 3 + O * → O 2 + 2O 2 ............ (5) O 3 + O 2 - → O 3 - + O 2 ... ............ (6)

On the other hand, the present inventors have studied in the above-mentioned ozone concentration reduction and its countermeasures, and found that by mixing a small amount of nitrogen gas (or air) into the oxygen gas sent to the ozone generator, the ozone concentration can be prevented from being reduced. It has been found out and proposed as Japanese Patent Application No. 11-354650. That is, as shown in the following formulas (7) to (8), a small amount of nitrogen is mixed with oxygen and sent between the electrodes of the ozone generator, and the nitrogen molecules are excited by the discharge, which reacts with the oxygen molecules to oxidize the nitrogen. with a group of objects (NO _X) occurs, the nitrogen oxides and the active oxygen react.

Moreover, the nitrogen oxide and the active oxygen react faster than the reaction between the ozone and the active oxygen to decompose the active oxygen into oxygen molecules or oxygen atoms. This gives equations (9) to (1
As shown by (0), active oxygen becomes N before reacting with ozone.
And O _X reaction, decomposition by active oxygen of the ozone is suppressed as a result. ^{_{N 2 + e → 2N * +}} e ............ (7) N * + O 2 → NO + O ............ (8) NO + O * → NO + O 2 ............ (9) NO + O ₂ ^* → NO ₂ + O ............ (10)

Further, based on the fact that the incorporation of a trace amount of nitrogen gas into oxygen gas as described above contributes to the suppression of ozone decomposition by active oxygen, the inventor of the present invention used the material for the raw material gas piping system of the ozone generation equipment. After reviewing the research,
It was found that the material of the gas conduit C connecting the oxygen facility A and the ozone generator B in FIG. 3 is related to the decrease in the concentration of ozone generated by the ozone generator B.

That is, if the gas conduit C is a conventionally used stainless steel tube, the concentration of ozone generated by the ozone generator B decreases with the elapse of operation time. Was replaced with a tube made of another material, and it was found that, depending on the material of the gas conduit, the ozone concentration hardly decreased even after continuous operation for a long time.

In view of the above, the present invention is based on the findings obtained in the above-mentioned research, properly selecting the material of the gas conduit connecting the oxygen equipment and the ozone generator, and operating the ozone generator continuously for a long time. An object of the present invention is to provide an ozone generator capable of stably maintaining an ozone concentration obtained in an early stage of operation even in such a case.

[0016]

According to the present invention, in order to attain the above object, according to the present invention, a high-purity oxygen gas supplied from an oxygen facility is generated by combining an oxygen facility with a silent discharge type ozone generator. Ozone generation equipment for introducing the device to ozone, wherein a gas conduit is provided between an oxygen supply port of the oxygen equipment and a gas inlet of the ozone generator, and oxygen gas is supplied to the ozone generator through the gas conduit. (1) The gas conduit is a tube made of a nonmetallic material (claim 1). (2) Using the gas conduit as a metal tube and coating the inner surface with a non-metallic material (claim 2). (3) In the above items (1) and (2), any one of a fluorine resin, a vinyl resin, and a polyamide resin is used as the nonmetallic material of the gas conduit (claim 3).

As described above, a fluorine resin,
By using a tube made of a non-metallic material such as vinyl resin or polyamide resin or a metal tube whose inner surface is coated with the above material, the ozone concentration can be maintained even if the ozone generator is continuously operated for a long time. It has been confirmed from experimental results that the concentration during the initial operation is maintained stably.

That is, the nitrogen gas adsorbed on the non-metallic material in the gas conduit is released little by little, mixed into the high-purity oxygen gas flowing through the gas conduit, and sent to the ozone generator at the subsequent stage. (Japanese Patent Application Hei 11-
As in 354650), nitrogen molecules are excited by discharge,
It is presumed that nitrogen oxides are generated by reacting with oxygen molecules, and the nitrogen oxides and active oxygen react to decompose active oxygen into oxygen molecules or oxygen atoms, thereby suppressing the decomposition of ozone by active oxygen. Is done.

[0019]

FIG. 1 is a block diagram showing an embodiment of the present invention.
A description will be given based on the examples (a) to (c). In the drawings of the embodiment, members corresponding to those in FIG. That is, the ozone generation equipment of the embodiment is basically the same as that of FIG. b) In the embodiment shown in FIG.
Uses a non-metallic fluororesin tube C-1.

Here, the gas conduit C in FIG.
FIG. 2 shows the results of experiments conducted by the inventor when the fluororesin tube C-1 was used and when the stainless steel tube shown in FIG. 3B was used as a comparative example. FIG. 2 shows the transition of the discharge time (operation time) of the ozone generator B and the concentration of the generated ozone measured at the outlet of the ozone generator. The fluororesin tube C-1 has a thickness of about 1 mm,
A tube having an outer diameter of 6 to 10 mm was employed.

As is clear from this characteristic diagram, when a stainless steel pipe is used for the gas conduit C, the ozone concentration decreases with the lapse of operation time (in the early stage of operation, the ozone concentration decreases by 2%).
After 200 g / Nm ³ a was the ozone concentration has elapsed operating time 4.5 hours, to the reduced are) to about 100 g / Nm ^3, was adopted fluororesin tube C-1 to the gas conduit C In this case, almost no decrease in ozone concentration was observed, indicating that the ozone concentration obtained in the early stage of operation was maintained stably as it was.

In the illustrated embodiment, a fluorine resin pipe is shown as the gas conduit C. However, the same effect can be obtained by using a pipe made of a polymer material such as vinyl resin or polyamide resin. Has been confirmed in experiments. FIG. 1C shows another embodiment of the gas conduit C. In this embodiment, the inner peripheral surface of a stainless steel pipe C-2 is covered with a fluororesin C-3 having a thickness of about 1 mm. I have.
Also in this embodiment, it has been experimentally confirmed that the same effects as those of the fluororesin tube C-1 in FIG. 1B can be obtained.

The same effect can be obtained by using a vinyl resin or a polyamide resin in addition to the fluororesin as the nonmetallic material for coating the inner surface of the stainless steel pipe C-2. This embodiment is effective when a large-scale ozone generating facility requires sufficient mechanical strength for its piping system. It has been confirmed by experiments that the material of the outlet pipe of the ozone generator B does not affect the stability of the ozone concentration.

As described above, according to the present invention, a gas pipe for supplying oxygen gas which is piped between an oxygen facility and a silent discharge type ozone generator at the subsequent stage is replaced with a conventional stainless steel pipe. By using a tube made of a non-metallic material such as fluororesin, vinyl resin, or polyamide resin, or a tube in which the inner surface of a steel tube is covered with the same non-metallic material as above, the ozone generation process of the ozone generator can Ozone decomposition due to active oxygen generated by the discharge can be suppressed, and a stable concentration of ozone gas can be obtained even after a long continuous operation.

[Brief description of the drawings]

FIG. 1 shows an ozone generation facility according to an embodiment of the present invention,
(a) is a system diagram, (b), (c) is a cross-sectional enlarged view of a gas conduit corresponding to claims 1 and 2 of the present invention, respectively

FIG. 2 is a characteristic diagram showing a relationship between an ozone concentration and a discharge time in comparison between the present invention and a conventional example based on experimental data of an ozone generator.

FIG. 3 shows a conventional ozone generation facility, in which (a) is a system diagram and (b) is an enlarged cross-sectional view of a gas pipe in (a).

4 shows an ozone generator used in the equipment of FIG. 3, (a) is a cross-sectional view of the entire apparatus, and (b) is a cross-sectional view of a high-voltage electrode portion in FIG.

[Explanation of symbols]

 A oxygen equipment B ozone generator C gas conduit C-1 fluororesin pipe C-2 stainless steel pipe C-3 fluororesin (coating layer)

Claims (3)

[Claims] 1. An ozone generating apparatus that combines an oxygen facility and a silent discharge type ozone generator to guide high-purity oxygen gas supplied from the oxygen facility to the ozone generator to ozonize the oxygen equipment. A gas pipe is provided between the mouth and the gas inlet of the ozone generator, and the oxygen pipe is supplied to the ozone generator through the gas pipe. Characterized ozone generation equipment. 2. An ozone generating apparatus which combines an oxygen facility and a silent discharge type ozone generator and guides high-purity oxygen gas supplied from the oxygen facility to the ozone generator to ozonize the oxygen facility. A gas pipe is provided between the mouth and the gas inlet of the ozone generator, and the oxygen gas is supplied to the ozone generator through the gas pipe. Ozone generating equipment characterized by being coated with a material. 3. The ozone generating equipment according to claim 1, wherein the non-metallic material of the gas conduit is any one of a fluorine resin, a vinyl resin and a polyamide resin.