JPH09103644A - Apparatus for treating volatile organic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for treating volatile organic compounds in which a photochemical reaction velocity is high, photocatalytic reaction efficiency is high, and the regeneration/exchange process of substances having photocatalytic activity is easy. SOLUTION: The main part of an apparatus 10 for treating volatile organic compounds is constituted from a reaction column 12 having a gas suction port 14 and a gas discharge opening 16. The other end of a pipe 18 the one end of which is connected to the upper part of the column 12 is connected with the lower end of the column 12, the circulation system of photocatalyst powder is composed of the pipe 18 and the column 12, and a powder transfer pump 22 which circulates and sprays titanium oxide powder 20 is connected with the pipe 18. An oscillation-dispersion plate which oscillates vertically to disperse and suspend the photocatalyst powder 20 in the column 12 and an ultraviolet lamp 30 which emits light necessary for the photocatalytic reaction are arranged in the column 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment device for volatile organic compounds, and more particularly to a treatment device for volatile organic compounds having good treatment efficiency by applying oxidative decomposition by photocatalytic activity.

[0002]

2. Description of the Related Art Volatile organic compounds are used in large amounts in a wide variety of industries as cleaning liquids and solvents, and environmental pollution caused by being discarded in the atmosphere and soil has become a serious problem.

Sources of high-concentration volatile organic compounds include factories and cleaning shops that use a large amount of organic solvents or organic cleaning liquids. There is a concern that pollution will spread widely in the soil, groundwater, and air in the country. Some of these volatile organic compounds are suggested to have carcinogenicity, and there is a risk of serious effects including health damage, and effective treatment methods for these are being investigated.

The following methods are currently known as treatment methods for purifying pollutants composed of volatile organic compounds.

For example, there is an atmospheric diffusion method by aeration. This is a method in which a gas containing a low-concentration organic compound is directly diffused into the atmosphere and expected to be diluted in the atmosphere, and cannot be said to be an essential removal method.

Further, there is an activated carbon adsorption method in which a gas containing an organic compound is treated with activated carbon. According to this method, the target organic compound can be removed from the gas to below the detection limit, but when the adsorption limit is exceeded. Replacement of activated carbon is required. In addition, it is necessary to treat the activated carbon itself that has adsorbed the organic compound, and it is necessary to treat a waste liquid containing a high concentration of the organic compound that is discharged when the activated carbon is regenerated.

Further, as a method for decomposing the organic compound itself, there is a catalytic thermal decomposition method. According to this method, there is no concern about secondary pollution, but, for example, when treating trichlorethylene (hereinafter referred to as TCE), 200 to
It is catalytically oxidized at a high temperature of 400 ° C., requires a large-scale facility, and consumes a huge amount of energy.

As another method for decomposing organic compounds, there is a method utilizing the action of microorganisms, but there is a limit to the treatment capacity of microorganisms. Therefore, it is effective for low-concentration and wide-range pollution, but is not suitable for treating high-concentration organic compounds.

In recent years, among volatile organic compounds, a volatile organic chlorine compound such as TCE, which is widely used as a solvent, has become a problem as a pollutant. As a method for purifying soil / groundwater containing TCE, currently, an atmospheric aeration method by aeration and an activated carbon adsorption method are generally used. All of these methods have the same problems as described above.

On the other hand, when a substance having a photocatalytic activity (hereinafter referred to as a photocatalyst) such as titanium oxide is irradiated with ultraviolet rays, radicals having a strong oxidizing ability are generated, and the radicals generate substances to be oxidized in a liquid and a gas. It is known to be oxidized.

It has been proposed to apply the photocatalytic activity to treat the organic compound. For example, Japanese Patent Publication No.
-54511 describes a method for purifying a fluid, in which titanium oxide is made into a porous lump by a light-transmitting substance, dispersed in the fluid, and photodecomposed by irradiation with ultraviolet rays. According to this method, since the titanium oxide is made into a lump by the binder, the surface area involved in the photocatalytic reaction is reduced,
There is a problem of poor reaction efficiency.

A method for purifying contaminants in water by suspending fine particles of titanium oxide in water has also been proposed. However, the reaction rate is slow in the solid-liquid reaction, and the powder and the liquid to be treated after the treatment have been proposed. There is a problem in that a complicated solid-liquid separation step for separating and is not necessary for continuous treatment.

In order to eliminate the need for this solid-liquid separation step, there is also a method in which a photocatalyst-immobilized film is formed by sintering, a binder or the like, and a volatile organic compound in an aqueous solution is brought into contact with it, and photodecomposition is carried out by irradiation with ultraviolet rays. Proposed.

However, in the method for forming an immobilized film using a binder or the like, the surface area of the photocatalyst effective for the reaction is reduced, the reaction rate is further lowered as compared with the suspension method, and it takes time to decompose and remove the organic compound. Further, when continuous treatment is performed, there is a phenomenon in which insoluble components such as calcium carbonate derived from impurities contained in the wastewater adhere to the surface of the immobilization membrane to clog the surface and the photocatalytic activity decreases. Therefore, there is a problem that it is necessary to regenerate the immobilization membrane by periodic cleaning with a chemical solution or to replace the immobilization membrane.

In order to improve the slow reaction rate in the aqueous solution, a method of vaporizing a volatile organic compound in water by aeration and then contacting it with the photocatalyst-immobilized membrane and photolyzing it by irradiating ultraviolet rays is also available. Proposed. According to this method, although the reaction rate is improved, there are problems with the immobilization membrane, namely, reduction of the reaction surface area and regeneration / immobilization of the immobilization membrane.
Problems such as the need for a replacement process will still exist.

[0016]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, to provide a fast reaction rate, good photocatalytic reaction efficiency, and easy regeneration / exchange process of a substance having photocatalytic activity. Another object is to provide a treatment device for volatile organic compounds.

[0017]

As a result of earnest studies, the present inventors have found that the above problems can be solved by continuously photooxidizing and decomposing volatile organic compounds by a solid-gas reaction by a photocatalyst. Found and completed the present invention.

The volatile organic compound treating apparatus according to claim 1 of the present invention is connected to a reaction tower having a gas inlet for supplying a gas to be treated and a gas outlet for discharging the treated gas, and the reaction tower. And a powder transfer pump that circulates the photocatalyst powder and sprays it into the reaction tower, and a vibration dispersion plate that is supported by the reaction tower so that it can vibrate vertically and that vibrates to disperse and suspend the photocatalyst powder in the reaction tower. And a light source for irradiating the photocatalyst powder in the reaction tower with light.

According to this apparatus, a volatile organic compound such as TCE is brought into contact with a photocatalyst powder such as titanium oxide to react with them while irradiating ultraviolet rays in a gas phase, so that the reaction rate is fast and the photooxidation is highly efficient. In addition, it can be decomposed, and since the photocatalyst is circulated in the form of a powder for continuous treatment, there is no need for a treatment process for reduction of photocatalytic activity due to immobilization or deterioration of the immobilization membrane, resulting in high efficiency in a continuous manner. Target processing can be performed.

A volatile organic compound treatment apparatus according to a second aspect of the present invention is connected to a reaction tower having a gas inlet for supplying a gas to be treated and a gas outlet for discharging the treated gas, and the reaction tower. And a powder transfer pump that circulates the photocatalyst powder and disperses the photocatalyst powder in the reaction tower, a glass fiber mesh carrying the scattered photocatalyst powder, and a light source that irradiates the photocatalyst powder in the reaction tower with light. It is characterized by that.

According to this apparatus, in addition to the features of the treatment method according to claim 1, the function that the photocatalyst powder adheres to the glass fiber surface under light irradiation conditions and exhibits an adhesion strength that does not drop by aeration and washing with water. By utilizing, the photocatalyst powder can be sprayed in the device without performing the immobilization treatment in advance, so that the photocatalyst film can be formed on the glass fiber surface in the device. By doing so, the maximum photocatalytic oxidation function of the catalyst can be maintained.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a schematic sectional view showing a treatment device 10 for volatile organic compounds according to Embodiment 1.

A main part of the volatile organic compound processing apparatus 10 of FIG. 1 is constituted by a reaction tower 12 having an inner diameter of 50 cm and a height of 2 m, for example. The reaction tower 12 has a gas inlet 14 for introducing the gas to be treated into the reaction tower 12 and a gas outlet 16 for discharging the treated gas. As shown in FIG. 1, the gas to be treated is introduced into the reaction tower 12 through the gas inlet 14 at the bottom of the reaction tower 12,
After being retained and treated, the gas is discharged to the outside of the reaction tower 12 through the gas discharge port 16 in the upper part of the reaction tower 12.

The other end of the pipe 18, one end of which is connected to the upper portion of the reaction tower 12, is connected to the lower end of the reaction tower 12, and the pipe 18 and the reaction tower 12 constitute a circulation system for photocatalyst powder. . A powder transfer pump 22 for circulating and spraying titanium oxide powder 20, which is a photocatalyst powder, in the pipe 18.
Is connected. The powder transfer pump 22 is connected to a driving means such as a motor (not shown) and its control means.

Inside the reaction tower 12, a vibration dispersion plate 24 is disposed which is vertically oscillatably supported by the reaction tower 12 and which vibrates to disperse and suspend the photocatalyst powder 20 in the reaction tower 12. The dispersion diaphragm 24 is appropriately vibrated in the vertical direction by a known driving means such as a motor and a crank (not shown). The dispersion vibrating plate 24 is constituted by a wire rod 28 fixed to a vibrating rod 26 that transmits the vibration from the driving means.

The frequency of the dispersion diaphragm 24 is 100 to 100.
It is preferable to operate in the range of 0 rpm (times / min). Usually, sufficient dispersion is performed at about 150 to 300 rpm (times / min), but when titanium oxide particles agglomerate to cause clogging of the wire net 28, the number of vibrations can be increased.

FIG. 2 is a front view showing the wire net 28. The wire mesh 28 fixed to the vibration dispersion plate 24 has a diameter smaller than the inner diameter of the reaction tower 12, the center thereof is fixed to the vibration rod 26, and the ultraviolet lamp 30 and its holding portion can penetrate near the periphery. An opening 32 of various sizes is provided.

The size of the mesh of the wire net 28 can be appropriately selected from the viewpoint of the particle size of the titanium oxide powder 20 and the dispersion efficiency. Further, the number of the wire nets 28 arranged can be appropriately selected from the viewpoint of the size of the reaction tower 12 and the dispersion efficiency.

An ultraviolet lamp (black light) 30 which is a light source for irradiating the light necessary for the photocatalytic reaction is arranged along the outer periphery of the reaction tower 12.

A powder recovery chamber 36 having a hopper 34 for recovering and storing the dropped titanium oxide powder 20 is disposed below the reaction tower 12. The titanium oxide powder 20 collected here is the powder transfer pump 2 connected to the reaction tower 12.
2 is circulated through the pipe 18 to the top of the reaction tower 12 and sprayed.

The volatile organic compound processed by the processing apparatus 10 is vaporized in advance by a method such as vacuum extraction, aeration (aeration), suction, etc. to be a gas to be treated.

The gas processed by the processing apparatus 10 is
The titanium oxide powder 20 is separated from the titanium oxide powder 20 by a filter (not shown) arranged at the gas discharge port 16 and discharged to the outside of the reaction tower 12.

Taking TCE as an example, the titanium oxide surface irradiated with ultraviolet rays in the presence of oxygen and water is decomposed into carbon dioxide and hydrogen chloride as shown in the following formula 1.

CHCl ₃ + 1 / 2O ₂ + H ₂ O → CO ₂ + 3HCl (Titanium oxide + UV irradiation condition) (Equation 1) As a condition for the above reaction, oxygen exists in the atmosphere at room temperature and atmospheric pressure. As for the amount, it has been confirmed that water is sufficient to have a saturated vapor pressure at room temperature, and no special operation is required when aeration of a volatile organic compound in the atmosphere. However, when the oxygen concentration in the introduced gas is extremely low, such as when vaporizing by a vacuum extraction method or the like, it is possible to mix the atmosphere and adjust the oxygen concentration in the gas to be treated to 10% or more, It is preferable in terms of reaction efficiency.

Since hydrogen chloride is present in the treated gas of TCE as shown in the above formula 1, it is environmentally unfavorable to release the treated gas as it is into the atmosphere. Therefore, it is necessary to provide the dehydrochlorination device 38 connected to the gas outlet 16 to remove hydrogen chloride.

The dehydrochlorination device 38 comprises a reaction tank 38A filled with water and a pipe 38B having pores for releasing the gas to be treated from the bottom of the reaction tank into water. The treated gas containing hydrogen chloride discharged from the reaction tower 12 is introduced into a pipe 38B provided at the bottom of the reaction tank 38A of the dehydrochlorination apparatus 38 connected to the gas outlet 16.
It is discharged into the water through the pores of the pipe 38B. Here, highly water-soluble hydrogen chloride (HCl) is dissolved in water, and carbon dioxide (CO ₂ ) remains in a gas state.

The exhaust gas containing CO ₂ as a main component can be directly discharged to the atmosphere. Further, the wastewater containing HCl can be discharged after adjusting the pH in a pH adjusting tank (not shown) to a neutral region.

The titanium oxide powder 20 is used as a photocatalyst in this processing apparatus 10, but the photocatalyst is not limited to this and, for example, a substance having a photocatalytic activity as described in JP-B-2-9850. Any substance known as can be used. Among the photocatalysts, titanium oxide, iron oxide, tungsten oxide, zinc oxide, strontium titanate and the like are widely known as typical ones, and of these, from the viewpoint of photocatalytic activity effect, safety and cost, The titanium oxide used in this Example 1 is preferred.

Further, in order to improve the photocatalytic activity of these photocatalysts, a metal which coexists with them and can be a reduction reaction site in the photocatalytic reaction, for example, platinum, gold, palladium, silver, copper, nickel, cobalt is used. A metal selected from the group can be used together. Of these,
From the point of effect, platinum, gold, palladium and silver are preferable,
Palladium is particularly preferable from the viewpoint of ease of processing and cost.

The particle size of the titanium oxide powder 20 is not particularly limited, but is 0.1 to 10 μm from the viewpoint of dispersibility and reactivity.
It is preferred that it is about.

Further, the light quantity of the ultraviolet lamp (black light) 30, which is a light source for irradiating the light necessary for the photocatalytic reaction, is 0.1 mW / cm ² or more (wavelength 380) on the surface of the photocatalyst.
nm) is preferred.

In this embodiment, the vibration dispersion plate 24 is
The wire rod 28 is fixed to the vibrating rod 26 that transmits the vibration from the driving means, and the vibration periods of the respective vibration dispersion plates 24 are the same. According to this aspect, there is an advantage that the driving portion and the transmitting portion existing in the reaction tower 12 are small, but from the viewpoint of reactivity, the vibration periods of the respective vibration dispersion plates 24 do not necessarily have to coincide with each other, and a plurality of vibration periods are not necessary. Alternatively, the vibration dispersion plate 24 may be fixed to the vibration rod 26, or the vibration dispersion plates 24 may be independently vibrated by another mechanical or electromagnetic method.

Although the present invention adopts a method of vibrating the vibration dispersion plate 24 as a method of vibration dispersion of the titanium oxide powder 20, other dispersion methods are not excluded. A method of raising and dispersing with a gas fluid, a method of dispersing with ultrasonic waves, and the like can also be applied. From the viewpoint of dispersion efficiency, it is preferable to use the vibration dispersion plate 24, but other means may be used alone depending on the reaction conditions.
Alternatively, they can be applied in combination.

Reaction tower 1 constituting the main part of the processing apparatus 10
The size of 2 can be appropriately selected depending on the TCE concentration in the introduced gas, the target removal rate, the strength of the ultraviolet lamp, and the like. For example, when the concentration of the volatile organic compound to be treated is high, the volume of the reaction tower 12 is reduced, or the usage amount of the titanium oxide powder 20 is increased, the ultraviolet lamp 3
The desired reaction efficiency can be obtained by increasing the strength of 0, the number of arrangements, and increasing the residence time of the gas to be treated in the reaction column 12.

In the case of the processing apparatus 10 of the first embodiment, the inflow T
CE concentration is 100 ppm, reaction tower 1 for the gas to be treated
2 residence time is 15 minutes, throughput is 1.5 per hour
m ³ . (Embodiment 2) FIG. 3 is a schematic sectional view showing a treatment device 40 for volatile organic chlorine compounds according to Embodiment 2. In this Example 2, the glass fiber mesh 4 installed in the reaction tower 12
The method of adhering and forming a photocatalytic film on the glass fiber 44 of No. 2 is adopted.

The reaction tower 12, which constitutes the main part of the processing apparatus 40, such as the gas inlet 14 for introducing the gas to be treated of the volatile organic compound, the ultraviolet lamp 30 which is the light source for causing the photocatalytic reaction, and the titanium oxide powder 20. The powder transfer pump 22, the pipe 18, and the like that constitute the circulation system are the same as those in the processing apparatus 10 of the first embodiment, and the conditions of the gas to be processed when the gas to be processed is TCE and the post-treatment of the processed gas are performed. The method (dehydrochlorination treatment) is also the same as in Example 1.

In the processing apparatus 40 of the second embodiment, for example, a plurality of stages of glass fiber nets 42 having glass fibers 44 fixed to a frame are provided inside the reaction tower 12 having an inner diameter of 40 cm and a height of 2 m. ing.

As shown in the front view of FIG. 4, the glass fiber net-like member 42 is constructed by fixing small-diameter glass fibers 44 to the frame 46 in a grid pattern at equal intervals. Around the frame 46, an opening 48 having a size that allows the ultraviolet lamp 30 and its holder to pass therethrough is provided.

The photocatalyst powder 20 is supported on the glass fiber 44 for use. Therefore, from the viewpoint of reaction efficiency, the glass fiber mesh 42 has an effective specific surface area of 50 to 100 m ² / m. It is preferable to set an appropriate diameter and arrangement interval of the glass fibers 44 so as to be ³ . Here, the effective specific surface area means the surface area of the glass fiber 44 per unit volume of the photocatalyst that can be immobilized.

In the case of the processing apparatus 40 of Example 2 having an effective specific surface area of 100 m ² / m ³ , the glass fiber net 42 in which the glass fibers 44 having a diameter of 2 mm are fixed to the frame 46 in the form of a grid having a pitch of 5 mm, Vertically 1
They are arranged at intervals of 2.5 mm, and the actual volume in the tower is 90% of the total volume.

Titanium oxide powder 20 is glass fiber 4
The principle that the titanium oxide powder 20 is adhered and carried on the No. 4 is caused by polarization of the titanium oxide powder 20 by light irradiation, and static electricity is generated on the surface of the glass fiber 44.

It has been confirmed that the thin film of titanium oxide formed by electrostatically adhering on the glass fiber 44 does not peel off by washing with water or aeration and has sufficient photocatalytic activity.

The use density of the titanium oxide powder 20 is
Although it depends on the conditions such as the concentration of the substance to be treated, it is usually preferably 100 mg / m ² or more. In this Example 2, the specific surface area is 100 m ² / m ³ , so the photocatalyst density is 10 g. / M ³ or more.

As a method for forming a titanium oxide film on the surface of the glass fiber 44, there is a method of filling the gas to be treated in the tower and sprinkling the dried titanium oxide powder 20 from the top of the reaction tower 12 under the condition of ultraviolet irradiation. To be After spraying, the titanium oxide film is formed on the surface of the glass fiber 44 by irradiating with ultraviolet rays for about 10 minutes.

When the titanium oxide powder 20 does not sufficiently disperse on the surface of the glass fiber 44 and is not sufficiently dispersed and a uniform film of titanium oxide is not formed on the surface of the glass fiber 44, the glass fiber network structure 42 is vibrated. It is preferred to provide powder 20. in this case,
The same driving means as that for driving the vibration dispersion plate 24 in the processing apparatus 10 of the first embodiment is provided with the glass fiber network structure 42.
Can also be applied.

As another method of forming the titanium oxide film, the gas to be treated is filled in the reaction tower 12 and the titanium oxide slurry (titanium oxide powder 2
0 dispersed in water at a concentration of 10 to 20 g / liter)
Can be continuously sprayed from the top of the reaction tower 12. After continuously spraying for about 5 minutes, stop the slurry supply,
The ultraviolet lamp 30 is irradiated for about 20 to 30 minutes to evaporate the water adhering to the titanium oxide powder 20 and form a titanium oxide film on the surface of the glass fiber 44.

Since the photocatalytic activity of the titanium oxide film formed on the surface of the glass fiber 44 decreases with time due to adhesion of dirt and the like, the above film forming method is appropriately repeated depending on the concentration of the dirt component of the introduced gas. It is preferable that the titanium oxide powder 20 is fixed again after the above. When the re-fixing is performed, the titanium oxide coating adhered is partly peeled off due to the stress applied during the re-fixing process, but most of it remains on the glass fiber 44, and the titanium oxide powder 2 is deposited on the glass fiber 44.
0 further adheres to form a new film. For this reason,
Titanium oxide is maintained on the carrier such as the glass fiber 44 with a constant film thickness.

In normal operation, the titanium oxide powder 20 is sprayed once every 100 hours. According to this method, maintenance can be performed more easily than with an immobilization film formed by sintering or the like, and thus a high photocatalytic activity effect can be maintained without requiring complicated steps.

In the processing apparatus 40 of Example 2, the inflowing TCE concentration was 100 ppm, the processing gas had a residence time of 15 minutes in the reaction tower 12, and the processing capacity was 1 m / hour.
^{Was 3} .

In the processing device 40 of the second embodiment, since the glass fiber structure 42 is filled, the attenuation of the light from the ultraviolet lamp 30 becomes large. Therefore, compared with the processing device 10 of the first embodiment, Although the inner diameter of the reaction tower 12 is set small, if the number and arrangement method of the ultraviolet lamps 30 and the material, size and arrangement interval of the glass fibers 44 are changed so that the ultraviolet intensity is increased even in the central portion of the reaction tower 12,
It is possible to make the inner diameter of the reaction tower 12 larger.

Also, instead of the glass fiber 44,
Light-transmissive, does not deteriorate due to photocatalytic reaction, and
Other materials that are resistant to oxidation and easy to process can also be used as the carrier for the titanium oxide powder 20. From the viewpoint of durability and processing into a fiber shape to obtain a large surface area, the glass fiber of this example is most suitable,
When the processing apparatus of the type in which the carrier itself is replaced after a certain period of time or the physical properties of the object to be processed are met, for example, a metal, resin, carbon, or the like processed into a fiber shape can be used. (Experimental Example 1) Using the processing apparatus 40 of the second embodiment, T
The graph of FIG. 5 shows the results of treating CE and measuring the TCE concentration with FID (hydrogen flame ionization detector) over time. The initial TCE concentration was 100 mg / liter. At this time, the oxygen concentration in the gas to be treated was 20% and the water content was 0.
As the titanium oxide powder 20, a dry powder having an average particle diameter of 1 μm was used. The irradiation light is assumed to be sunlight on a clear day, and 5 mW / cm ² is irradiated at a wavelength of 360 nm.
Six 15 W ultraviolet lamps 30 were used as light sources. The photocatalyst specific surface area was 1 m ² / m ³ .

As is apparent from the graph, the TCE decomposition treatment was carried out rapidly, 80% or more of which was treated in the first 5 minutes, and the TCE remaining after 15 minutes was 0.2 mg / liter, which was 99%. It became clear that the above was decomposed.

To describe the features of each of the above-described embodiments, since titanium oxide is used as the powder 20 in the first embodiment, continuous supply of the titanium oxide powder 20 by the transfer pump 22 and diffusion by the vibration dispersion plate 24 are required during the processing operation. However, the reaching distance of ultraviolet rays is long, and the pretreatment operation is unnecessary.

In Example 2, since the titanium oxide powder 20 was immobilized on the glass fiber 44 and used, the immobilization operation (dispersion, ultraviolet irradiation) was necessary, and the reaction tower 12 was used.
Due to the presence of the glass fiber net 42, the UV reach distance is shorter than that of the processing apparatus 10 of the first embodiment.
The number of operations during the processing operation is small, and the powder transfer pump 22 is used less frequently.

A suitable mode can be selected depending on the type and concentration of the volatile organic compound applied to the processing apparatus, the required processing speed, and the environment in which it is used. Further, in each of the above examples, since the purpose is to treat high-concentration TCE, the density of the glass fiber 44 and the amount of titanium oxide powder 20 used are high, but the gas of the organic compound to be treated is high. When the concentration is low, the concentration (use amount) of the titanium oxide powder 20, the intensity of the ultraviolet lamps 30, the number of the ultraviolet lamps 30 and the residence time of the gas to be treated in the reaction tower 12 can be further reduced.

When high-concentration TCE is treated, since a high-concentration hydrogen chloride gas is generated in the reaction tower 12 as described above, another chlorine compound is produced as a by-product or the treatment apparatus 10 is used. , 40 will promote the corrosion. Therefore, when treating an organic compound containing chlorine such as TCE, it is necessary to make the materials of the treatment devices 10 and 40 acid resistant.

Further, in order to absorb the hydrogen chloride gas generated in the reaction tower 12, it is also effective to add a device for intermittently spraying water in the reaction tower 12. When water is sprayed, the reaction rate decreases if a water film is formed on the surface of the titanium oxide powder 20, so that, for example, the inside of the reaction tower 12 is divided into a plurality of zones in the cross-sectional direction, and each zone from the top of the reaction tower 12 is divided into zones. It is preferable to spray water intermittently.

Although the reaction rate of the titanium oxide powder 20 in the water-sprayed zone is temporarily reduced, the titanium oxide powder 20 is dried by irradiation of ultraviolet rays over time. Even at that time, the titanium oxide powder 20 in the other zones is not affected by water, and the treatment is continuously performed with high reaction efficiency, and the effect of water spraying can be suppressed to a low level as a whole. The water spray time and spray interval for each zone are set according to the hydrogen chloride concentration. Further, it is possible to suppress the production of by-products by spraying with water.

The treated water in which hydrogen chloride is dissolved, which is used here, is recycled while the titanium oxide powder 20 is being mixed,
When the pH becomes higher than about 2, the powder may be separated and the supernatant liquid may be pH-adjusted for reuse, or the waste water from the dehydrochlorination unit 38 may be transferred to a pH-adjusting layer for processing. May be processed simultaneously.

In the treatment apparatus of the present invention, the photocatalyst powder is utilized in the gas phase reaction, so that the ability of the photocatalyst can be maximized. According to these devices, as is clear from the above-mentioned respective embodiments, for example, when TCE is targeted, even if the concentration of the introduced gas is as high as 100 ppm, 15
It is possible to decompose 99% or more into carbon dioxide gas and hydrogen chloride in a contact time of minutes, and it is possible to perform a very highly efficient treatment. As for other volatile organic compounds, any compound that can be decomposed by oxidation can be similarly used as an efficient processing apparatus.

The processing apparatus of the present invention can be used in all fields in which volatile organic compounds are generated and / or exist. The processing apparatus of the present invention has a simple structure as described above and has no problem of waste, so that the processing apparatus can be freely designed from small scale processing to large scale processing, and its application range is wide.

Specific application fields include, for example, environmental purification devices for the purpose of soil purification, water purification, atmospheric purification, etc., and wastewater and exhaust treatment devices in small-scale establishments such as factories and cleaning shops. be able to.

[0073]

The volatile organic compound treatment apparatus of the present invention does not require regeneration / exchange of a substance having photocatalytic activity, has good photocatalytic reaction efficiency, and has a high treatment speed for decomposing volatile organic compounds. Has the effect.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a volatile organic compound processing apparatus of Example 1.

FIG. 2 is a front view showing a metal net fixed to a dispersion diaphragm used in the volatile organic compound processing apparatus of Example 1.

FIG. 3 is a schematic sectional view showing a volatile organic compound processing apparatus of Example 2.

FIG. 4 is a front view showing a glass fiber mesh used in the volatile organic compound treatment apparatus of Example 2.

FIG. 5: TCE with the volatile organic compound treatment apparatus of Example 2
5 is a graph showing a change in TCE gas concentration when treated with.

[Explanation of symbols]

 10 Treatment Equipment for Volatile Organic Compounds 12 Reaction Tower 18 Powder Transfer Pump 22 Dispersion Vibration Plate 40 Treatment Equipment for Volatile Organic Compounds 42 Glass Fiber Network 44 Glass Fibers

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahisa Ogawa 1-5 Otsuka, Inzai-cho, Inba-gun, Chiba Inside Takenaka Corporation Technical Research Institute (72) Inventor Takeshi Hiromatsu 1-5 Otsuka, Inzai-cho, Inba-gun, Chiba Prefecture Bannaka Takenaka Corporation Technical Research Institute

Claims (2)

[Claims] 1. A reaction tower having a gas inlet for supplying a gas to be treated and a gas outlet for discharging the treated gas; and a photocatalyst powder which is connected to the reaction tower and circulated through the reaction tower. A powder transfer pump, a vibration dispersion plate vertically oscillatably supported by the reaction tower and vibrating to disperse and suspend the photocatalyst powder in the tower, and a light source for irradiating the photocatalyst powder in the reaction tower with light. An apparatus for treating volatile organic compounds, comprising: 2. A reaction tower having a gas inlet for supplying a gas to be treated and a gas outlet for discharging the treated gas; and a photocatalyst powder which is connected to the reaction tower and circulated through the reaction tower. A powder transfer pump, a glass fiber network carrying the scattered photocatalyst powder, and a light source for irradiating the photocatalyst powder in the reaction tower with light.