Ozone aeration device

Abstract

This ozone aeration device comprises: an ozone generator (10) for generating ozone gas; an ozone reaction device (14) in which a liquid to be treated is aerated with the ozone gas generated by the ozone generator; and a structure (16) for returning used and discharged ozone gas from the ozone reaction device to the gas intake side of the ozone generator. The discharged ozone gas is reused as part of raw material in the ozone generator and is incorporated into a substantially endless reuse loop. Therefore, a special discharged ozone decomposition treatment facility is not required, and the treatment of the discharged ozone can be performed with an extremely simple configuration.

Description

Ozone Aeration Equipment

[0001] The present invention relates to an ozone aeration device that aerates ozone gas into a liquid to be treated, thereby deodorizing, decolorizing, sterilizing, decomposing organic matter, and oxidizing inorganic or organic matter in the liquid.

[0002] Various types of ozone aeration systems are known, which generate ozone gas using an ozone generator and then aerate the ozone gas into a liquid to be treated using an ozone reactor (see, for example, Patent Document 1). In the ozone reactor, not all ozone gas is effectively consumed; some remains as waste ozone. The waste ozone is decomposed to a predetermined standard value or less without being released into the atmosphere. Known waste ozone treatment methods include (1) thermal decomposition, (2) chemical washing, (3) activated carbon adsorption, (4) catalytic contact, and (5) soil adsorption. Regardless of which waste ozone treatment method is adopted, costs (initial and running costs) are incurred. Initial costs include the need for a waste ozone tower filled with a catalyst or activated carbon and heating equipment using fuel gas. Running costs include the cost of heating the fuel gas and the cost of periodically replacing fillers such as catalysts or activated carbon.

[0003] Reuse of exhaust ozone has also been attempted. For example, Patent Document 2 discloses a technology for treating sludge in an aeration tank using microbial decomposition, in which a portion of the sludge is treated with ozone and then placed in the aeration tank, and the exhaust ozone generated during the ozone treatment is recovered and placed in the aeration tank, thus adding ozone treatment to the aeration tank using microbial decomposition. Patent Document 3 discloses recovering the exhaust ozone generated during ozone treatment and appropriately reusing the recovered exhaust ozone for another purpose. These technologies recover and reuse exhaust ozone, but no specific measures are taken to prevent exhaust ozone from being generated at the reuse site. Therefore, there is a possibility that the exhaust ozone will be released into the outside air to a greater or lesser extent. To prevent this, as with the above-mentioned conventional technology, it is necessary to install an exhaust ozone decomposition treatment facility at some stage.

[0004] Japanese Patent Publication No. 2003-190976 Japanese Patent Publication No. 2002-119991 Japanese Patent Publication No. 2004-122105

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an ozone aeration device that can treat waste ozone with a simple configuration.

[0006] The ozone aeration device according to the present invention comprises an ozone generator that generates ozone gas, an ozone reaction device that aerates a liquid to be treated with the ozone gas generated by the ozone generator, and a structure that returns exhaust ozone gas used in the ozone reaction device to the intake side of the ozone generator.

[0007] According to the present invention, exhaust ozone gas used in the ozone reaction device is not decomposed as in the conventional method, but is simply returned to the intake side of the ozone generator as a raw material, thereby allowing the exhaust ozone gas to be reused as part of the raw material in the ozone generator. Therefore, no special exhaust ozone decomposition treatment equipment is required, and exhaust ozone can be treated with an extremely simple configuration. Furthermore, a structure that reuses exhaust ozone gas as part of the raw material in the ozone generator creates a substantially infinite reuse loop, and therefore does not encounter the problems that could not be solved when reusing exhaust ozone for another purpose, as shown in Patent Documents 2 and 3 (problems with exhaust ozone at the reuse destination).

[0008] 1 is a block diagram showing the system configuration of an ozone aeration device according to an embodiment of the present invention.

[0009] In FIG. 1 , an ozone generator 10 is, for example, a type that incorporates a built-in UV (ultraviolet) lamp 11 and generates ozone gas by irradiating oxygen in the air with UV light. The liquid to be treated is pumped by a pump 12 and introduced into an ozone reactor 14 (ozone reactor) via an ejector 13. The ozone gas generated by the ozone generator 10 is drawn through the fluid inlet of the ejector 13 and introduced into the ozone reactor 14 together with the liquid to be treated. The ozone gas drawn through the fluid inlet of the ejector 13 turns into bubbles upon contact with the liquid to be treated, and the liquid to be treated containing this bubbly ozone gas is introduced into the ozone reactor 14. By allowing the liquid to be treated containing ozone gas to appropriately remain in the ozone reactor 14, the bubbly ozone gas OZ comes into contact with a larger amount of the liquid to be treated, thereby promoting aeration of the liquid to be treated with ozone. The ozone reactor 14 (ozone reactor) may be designed based on an existing ozone reactor design. Generally, an ozone reactor is designed so that the ozone absorption efficiency of the liquid to be treated in the ozone reactor is about 85 to 90%, and in carrying out the present invention, the ozone reactor 14 can be designed and configured in the same manner as existing ozone reactors.

[0010] The ozone reaction in the ozone reactor 14 deodorizes, decolorizes, sterilizes, decomposes organic matter, and oxidizes inorganic or organic matter in the liquid being treated. The liquid being treated (treated liquid) that has come into contact with ozone gas OZ in the ozone reactor 14 flows out of a drain outlet 15 of the ozone reactor 14. Used ozone gas (exhaust ozone gas) (which has come into contact with the liquid being treated) collects in an upper space 14U within the ozone reactor 14. In this embodiment, a pipe 16 is provided between the upper space 14U within the ozone reactor 14 and the ozone generator 10, and the exhaust ozone gas is returned to the intake side of the ozone generator 10 through the pipe 16. When ozone gas is drawn from the ozone generator 10 via the ejector 13, the exhaust ozone gas in the ozone reactor 14 is drawn into the ozone generator 10 through the pipe 16. In this way, the exhaust ozone gas used in the ozone reaction tower 14 is returned to the intake side of the ozone generator 10 and reused as part of the raw material for ozone generation. This circulation structure, which reuses the exhaust ozone gas as part of the raw material in the ozone generator 10, constitutes a substantially infinite reuse loop, so no decomposition treatment equipment for the exhaust ozone gas is required. Of course, the ozone generator 10 is configured airtight, so that the generated ozone gas or the exhaust ozone gas sucked through the piping 16 does not leak outside the system.

[0011] A check valve 17 communicating with the outside air is provided in the upper space 14U of the ozone reaction tower 14. The check valve 17 functions to prevent the exhaust ozone gas in the upper space 14U of the ozone reaction tower 14 from being released into the outside air, while also introducing outside air into the storage space (upper space 14U) for the exhaust ozone gas in the ozone reaction tower 14 in accordance with the negative pressure (or reduced pressure) of the storage space. This allows a shortage of raw material (air) to be replenished as needed.

[0012] A vortex pump may be used instead of the ejector 13 as a suction means for introducing the ozone gas generated by the ozone generator 10 into the liquid to be treated. Furthermore, because the exhaust ozone gas returned to the ozone generator 10 through the pipe 16 contains moisture, it is preferable to take some kind of measure to prevent condensation. For example, as shown in the figure, by configuring the ozone gas to be introduced into the ejector 13 (or vortex pump) from the bottom of the ozone generator 10, condensed water generated inside the ozone generator 10 can be easily discharged (sucked in by the ejector 13 or vortex pump). That is, it is advantageous to locate the suction mechanism (ejector 13 or vortex pump) that sucks the exhaust ozone gas into the ozone generator 10 below the ozone generator 10. In other words, it is advantageous to arrange the suction mechanism (ejector 13 or vortex pump) that draws the exhaust ozone gas into the ozone generator 10 in the path that supplies the liquid to be treated to the ozone reaction tower 14 so that it draws in the ozone gas generated by the ozone generator 10.

[0013] In the above embodiment, the ozone generator 10 is a type that uses a UV lamp 11. However, this is not limiting and a discharge-type ozone generator may also be used. However, as is well known, discharge-type ozone generators preferably use oxygen as a feedstock; using air as a feedstock is undesirable because it generates harmful nitrogen oxides (NOx). Furthermore, high humidity levels also have the disadvantage of reducing the amount of ozone generated. As described above, the exhaust ozone gas returned to the ozone generator 10 through the piping 16 contains moisture. Therefore, when using a discharge-type ozone generator 10, it is necessary to consider the fact that the amount of ozone generated will be lower (compared to when humidity is low). Therefore, when using a discharge-type ozone generator 10, it is desirable to take measures such as dehumidifying the inside of the piping 16 before the ozone generator 10 or continuously or intermittently draining condensation generated within the ozone generator 10. In this regard, a UV lamp-type ozone generator 10 is advantageous because the amount of ozone generated is not reduced by humidity. Furthermore, as described above, by configuring the ozone generator 10 so that ozone gas is introduced into the ejector 13 (or the vortex pump) from the bottom of the ozone generator 10, condensed water generated inside the ozone generator 10 can be easily discharged (sucked in by the ejector 13 or the vortex pump).

[0014] The mechanism for introducing ozone gas generated by the ozone generator 10 into the liquid being treated is not limited to suction mechanisms such as the ejector 13 or vortex pump. It is also possible to employ a pressure-feeding mechanism such as an air pump or compressor. In this case, measures must be taken in the pressure-feeding mechanism to account for the humidity of the exhaust ozone gas, and measures must also be taken in the pressure-feeding mechanism to prevent corrosion caused by ozone. Furthermore, when introducing ozone gas into the liquid being treated using a pressure-feeding mechanism such as a compressor, an air diffuser is often used to create small bubbles. This air diffuser is prone to clogging with fine fixed particles, such as suspended solids and turbidity components, in the water, and therefore requires periodic maintenance, such as cleaning or replacement. In this case, the air diffuser is installed at the bottom of the ozone reactor 14, which requires removal from the ozone reactor 14 for maintenance, which is inconvenient. In contrast, the ejector 13 and vortex pump are less susceptible to clogging, and even if maintenance is required, they are located outside the ozone reactor 14, making maintenance easy to perform. Therefore, in implementing the present invention, using a suction mechanism such as the ejector 13 or a vortex pump as a mechanism for introducing the ozone gas generated by the ozone generator 10 into the liquid to be treated is extremely advantageous in terms of measures against moisture contained in the exhaust ozone gas and ease of maintenance work.

[0015] It is also preferable to take measures against corrosion caused by ozone when using a suction mechanism such as the ejector 13 or a vortex pump. For example, it is recommended to use ozone-resistant materials (such as stainless steel such as SUS304 or SUS316, or ceramics) for the ejector 13, piping, and other components. Other ozone-resistant materials include titanium, aluminum, epoxy resin, fluorocarbon resin, silicone resin, ethylene propylene diene rubber (EPDM), and fluororubber (FKM), so these materials can be used for piping, packing, O-rings, and other components as needed.

[0016] If necessary, a pipe for returning the liquid to be treated from the ozone reaction tower 14 to the inlet side of the pump 12 may be provided so that the liquid to be treated can be circulated through the ozone reaction tower 14 as needed.

[0017] The liquid to be treated to which the present invention can be applied may be raw water for producing pure water used in semiconductor manufacturing processes, or may be contaminated water such as wastewater, and the present invention can be applied to the treatment of all types of liquids.

Claims

1. An ozone aeration device comprising: an ozone generator that generates ozone gas; an ozone reaction device that aerates a liquid to be treated with the ozone gas generated by the ozone generator; and a structure that returns exhaust ozone gas used in the ozone reaction device to the intake side of the ozone generator.

2. The ozone aeration device of claim 1, wherein the structure includes a pipe for returning the exhaust ozone gas to the intake side of the ozone generator, and a suction mechanism for drawing the exhaust ozone gas into the ozone generator through the pipe.

3. The ozone aeration device according to claim 2, further comprising a check valve for introducing outside air into the storage space for the exhaust ozone gas in accordance with the negative pressure in the storage space within the ozone reaction device.

4. The ozone aeration device according to claim 2, wherein the suction mechanism is an ejector or a vortex pump disposed below the ozone generator.

5. The ozone aeration device according to claim 2, wherein the suction mechanism is disposed in a path for supplying the liquid to be treated to the ozone reaction device so as to suck in the ozone gas generated by the ozone generator.

6. An ozone aeration device according to any one of claims 1 to 5, wherein the ozone generator is configured to irradiate the raw material gas with ultraviolet rays.

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