JPH0472761B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an oxygen recycling ozone generator, in particular, a long-term oxygen recycling ozone generator that prevents volatile organic matter and nitrogen coexisting with the treated material from being mixed into the recovered gas. This makes it possible to produce ozone stably and efficiently over time.

[Conventional technology]

Fig. 2 is a configuration diagram showing a conventional oxygen recycling ozone generator disclosed in, for example, Japanese Utility Model Publication No. 55-133286, in which 1 is a raw material gas reservoir, 2 is an ozone generator, and 3 is an ozone reaction tank. , 4 is the blower, 5
1 is a cooling dehumidifier, 6 is an adsorption gas dryer, 8 is a deaeration tower, 9 is a water nozzle, 10 is an exhaust pump, 11 is a water level detector, and 12 is a water level detector whose opening degree or opening/closing state is controlled. 13 is a water supply pump.

Next, the operation of this conventional device will be explained. The raw material oxygen discharged from the raw material gas reservoir 1 is converted into ozonized oxygen (the ozone concentration is usually several percent) in the ozone generator 2.
Aeration is diffused into the water to be treated as fine bubbles from the bottom of the ozone reaction tank 3. As a result, the ozone in the ozonized oxygen is dissolved in water and consumed. At this time, some of the oxygen is dissolved in the water and consumed, but the rest is discharged from the water. This discharged oxygen is suctioned and pressurized by a blower 4, and then sent to a cooling dehumidifier 5 at a temperature of 5°C to which low-temperature brine is sent from a refrigerator (not shown).
The water contained in the gas is condensed and removed as a drain. The gas exiting the cooling dehumidifier 5 is dried to a dew point of -40°C or less in an adsorption type gas dryer 6, and then sent to the raw material gas condenser 1 again as raw material oxygen. Such a circulation system is an oxygen recycling system. It is called. Note that an amount of oxygen equivalent to the oxygen converted to ozone and the oxygen dissolved in water and flowing out of the system is supplied as supplementary oxygen.

On the other hand, the material to be treated, that is, raw water, sent to the ozone reaction tank 3 is degassed in a degassing tower 8 to prevent nitrogen and volatile organic substances dissolved in the gas discharged from the ozone reaction tank 3 from being mixed in. be done. The degassing tower 8 is under reduced pressure by the exhaust pump 10, and raw water is sucked into the degassing tower 8 through the control valve 12. At this time, the raw water is sprayed from the water spray nozzle 9 and degassed. The water level detector 11 controls the opening degree of the control valve 12 so that the same amount of raw water as the amount of water sent from the deaeration tower 8 to the ozone reaction tank 3 by the water supply pump 13 is sucked through the control valve 12. It is installed to control the water level of the degassing tower 8 and keep it constant.

As mentioned above, it is extremely important to prevent volatile organic pollutants and nitrogen from being mixed into the oxygen gas in the oxygen recycling system in order to efficiently produce ozone. As stated in Journal of the Institute of Electrical Engineers of Japan B, Vol. 98, No. 2, p. 17, mixing 20% by volume of nitrogen causes a 15% decrease in ozone generation efficiency, and "Ozone Chemistry and Technology" published by the American Chemical Society (published in 1959) 305 As described on page 1, the incorporation of 1% by volume of organic matter has such a large adverse effect that no ozone is generated. Therefore, ozone can only be efficiently produced by using the degassing tower 8 to prevent volatile organic substances and nitrogen dissolved in the raw water from being mixed into the recycled gas.

FIG. 3 shows a second conventional example, in which numerals 1 to 6 indicate the same or equivalent components as in FIG. 2. A reactor 14 is provided with a heater or a lamp that emits ultraviolet rays, and is provided between the blower 4 and the cooling dehumidifier 5.

This second conventional example also operates in the same way as the first conventional example, but the raw water supplied to the ozone reaction tank 3 is not degassed, and dissolved volatile organic matter and nitrogen are removed from ozonized oxygen. It is expelled by aeration and sent to the reactor 14 together with the gas discharged from the ozone reaction tank 3. As explained in the first conventional example, when volatile organic substances coexist in the recycled gas, the ozone generation efficiency decreases significantly.
In the reactor 14, the volatile organic substances are reacted with ozone and decomposed into carbon dioxide and water, which either do not significantly affect ozone generation or can be removed in the liquid path system after the reactor 14. Specific examples of the reactor 14 include a heating type, a photoreaction type, etc., and each ozone reaction tank 3
The small amount of ozone, volatile organic matter, and oxygen gas containing water vapor recovered from the gas is heated and irradiated with light, and the oxidizing power of ozone oxidizes the volatile organic matter contained therein into water and carbon dioxide gas. In this way, ozone can be efficiently produced by removing volatile organic substances that have an adverse effect on ozone generation.

Note that if the amount of ozone necessary for oxidizing organic matter is insufficient in the amount contained in the oxygen recovered from the ozone reaction tank 3, the ozonized oxygen sent from the ozone generator 2 to the ozone reaction tank 3 is branched. In some cases, the reactor 14 is directly supplied through the branch line 15 and valve 16.

[Problem that the invention seeks to solve]

In order to remove volatile organic substances and nitrogen that have a negative effect on ozone generation, the first conventional example requires complicated configurations, controls, and power such as a vacuum pump and degassing tower, and the second conventional example requires a heating or light source. This increases the power consumption for ozone generation. Further, in the second conventional example, nitrogen is not removed at all, and there are problems such as a decrease in ozone generation efficiency due to the mixing of nitrogen into the recycled gas.

This invention was made to solve the above-mentioned problems, and is an oxygen recycling ozone generation system that has a simple configuration and can prevent volatile organic matter and nitrogen from being mixed into recovered oxygen without using any power. The purpose is to obtain equipment.

[Means for solving problems]

The oxygen recycling ozone generator according to the present invention comprises two or more ozone reaction tanks, the material to be treated is connected to each ozone reaction tank in series, and ozonated oxygen is supplied to each ozone reaction tank in parallel, The exhaust gas from the first ozone reaction tank to which the material to be treated is initially supplied is discharged outside the system, and the exhaust gas from the second ozone reaction tank from the second stage onward is collected and recycled. .

[Effect]

In this invention, by aerating ozonized oxygen into the first ozone reaction tank, volatile organic matter and nitrogen coexisting in the object to be treated are taken into the aeration gas and taken out of the ozone reaction tank. It is possible to prevent these volatile organic substances and nitrogen from being mixed into the subsequent exhaust gas from the ozone reaction tank, and the efficiency of ozone generation can be maintained at a high level at all times.

〔Example〕

FIG. 1 is a block diagram showing an oxygen recycling ozone generator according to an embodiment of the present invention when a liquid material is to be treated.
is the same as the conventional device. 3 is an ozone reaction tank which is divided into two reaction tanks 31 and 32 by providing a partition inside thereof, 7 is a waste ozone decomposer, and 21 and 22 are flow rate adjustment valves. The flow path connecting the ozone generator 2 and the ozone reaction tank 3 branches and is connected via a valve 21 and a valve 22 to the lower portions of the first and second ozone reaction tanks 31 and 32, which are respectively divided. Furthermore, as for the exhaust pipes to the reaction tanks, the first ozone reaction tank 31 is connected to the waste ozone decomposer 7, and the second ozone reaction tank 32 is connected to the blower 4.

Next, the operation of the above embodiment based on the present invention will be explained using FIG. The raw material oxygen discharged from the raw material gas reservoir 1 becomes ozonized oxygen (the ozone concentration is usually several percent) in the ozone generator 2, and is branched off to the first ozone reaction tank 31 via the rear valves 21 and 22.
Then, air is diffused into the liquid to be treated as fine bubbles from the bottom of the second ozone reaction tank 32. As a result, the ozone in the ozonized oxygen is dissolved in the liquid and consumed. The first ozone reaction tank 31 and the second ozone reaction tank 32 are separated by a partition wall except for the lower part of the tank, and air is diffused into the first ozone reaction tank 31 and the second ozone reaction tank 32. The gases are exhausted from the upper part of the ozone reaction tank 3 without mixing with each other. The exhaust gas from the first ozone reaction tank 31 completely decomposes unreacted ozone remaining in the waste ozone decomposer 7, and then is discharged to the outside of the system. After the exhaust gas from the second ozone reaction tank 32 is suctioned and pressurized by a blower 4, it is cooled to about 5°C by a cooling dehumidifier 5 to which low-temperature brine is sent from a refrigerator (not shown). The water that was present is condensed and removed as drain. The gas exiting the cooling dehumidifier 5 is dried in an adsorption type gas dryer 6 to a dew point of -40° C. or lower, and is again sent to the raw material gas reservoir 1 as raw material oxygen.

On the other hand, the liquid to be treated flows from the upper part of the first ozone reaction tank 31 and from the part of the first ozone reaction tank 31 and the second ozone reaction tank 32 without partition walls to the second ozone reaction tank 31.
into the ozone reaction tank 32. In this way, it reacts sufficiently with ozone in the first ozone reaction tank 31 and the second ozone reaction tank 32, and flows out of the system as a treatment liquid.

To explain the balance of substances in the first ozone reaction tank 31 and the second ozone reaction tank 32, ozone moves from bubbles into the liquid, oxidizes reducing substances in the liquid, and is consumed. The oxygen in the bubbles is mainly dissolved to a saturated state in the first ozone reaction tank 31, and most of it is recovered as exhaust gas in the second ozone reaction tank 32 without being dissolved in the liquid. Also,
Most of the volatile organic substances and nitrogen coexisting in the liquid move into bubbles in the first ozone reaction tank 31 according to dissolution equilibrium and are discharged to the outside of the system. Therefore, the second
When the liquid to be treated in the second ozone reaction tank 32 flows in, volatile organic substances and nitrogen are not contained in the liquid to be treated, and the exhaust gas recovered from the second ozone reaction tank 32 does not contain the above-mentioned volatile organic substances and nitrogen. Contamination with nitrogen can be prevented.

Even if the object to be treated is in the form of granular solids or slurry, the air filling the voids is replaced by the supplied ozonized oxygen, so it can be easily discharged from the system. Further, attached volatile organic substances can also be transferred to the gas phase and removed.

Note that the amount of ozonized oxygen supplied to the first ozone reaction tank 31 varies depending on the amount of liquid to be treated, pressure, and temperature, but it is sufficient that it is equal to or greater than the amount of oxygen dissolved in the liquid.
Also, the higher the amount, the more effectively volatile organic substances and nitrogen can be removed. However, if the supply amount is too large, oxygen consumption increases and the cost of ozone production increases. From these relationships, when using an aqueous solution, ozone can be produced without sacrificing economic efficiency by setting the gas/liquid ratio generally between 0.04 and 0.25.

Regarding supplementary gas, by introducing an oxygen recycling system, ozone can be produced at a lower cost than with an air-based ozone generator without using pure oxygen.
It has been experimentally determined that the lower limit of oxygen concentration in that case is 60% by volume. Further, in this embodiment, the ozone reaction tank 3 is divided by partition walls, but it goes without saying that the same effect can be obtained even if a plurality of ozone reaction tanks are each independent.

〔Effect of the invention〕

As described above, according to the present invention, the ozone reaction tank is composed of two or more tanks, the object to be treated is connected to each ozone reaction tank in series, and the flow of ozonated oxygen is connected to each ozone reaction tank in parallel. The exhaust from the first ozone reactor, into which the material to be treated first enters, is discharged to the outside of the system, and the exhaust from the second and subsequent ozone reactors is circulated to the ozone generator. This has the effect of preventing volatile organic matter and nitrogen from being mixed into the oxygen recovered from materials, making it possible to generate ozone with high efficiency at a low cost, and without using extra power.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an oxygen recycling ozone generator according to an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams showing conventional oxygen recycling ozone generators, respectively. In the figure, 1 is a raw material gas reservoir, 2 is an ozone generator,
3 is an ozone reaction tank, 31 is a first ozone reaction tank,
32 is a second ozone reaction tank, and 4 is a blower.
In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Ozonated oxygen emitted from the ozone generator is sent to an ozone reaction tank, and is reacted with the treated material sent to the ozone reaction tank, and the discharged oxygen is circulated to the ozone generator to produce raw material. In an oxygen recycling ozone generator that is used as oxygen, the ozone reaction tank is composed of two or more tanks, the object to be treated is connected in series to each of the ozone reaction tanks, and the flow of the ozonized oxygen is passed through each of the ozone reactions. The ozone reactor is supplied in parallel to the tanks, the exhaust from the first ozone reaction tank into which the object to be treated first enters is discharged to the outside of the system, and the exhaust from the second and subsequent ozone reactors is circulated to the ozone generator. An oxygen recycling ozone generator characterized in that: 2. The oxygen recycling ozone generator according to claim 1, wherein the flow rate of ozonized oxygen supplied to the first reaction tank is set to a gas/liquid ratio in the range of 0.04 to 0.25. 3. The oxygen recycling ozone generator according to claim 1 or 2, wherein the oxygen temperature in the raw material gas supplied to the ozone generator is 60 to 100%.