JPH0924244A - Exhaust ozone gas treatment device and its operating method - Google Patents

Abstract

(57) [Summary] [Objective] The performance of the exhaust ozone gas decomposition catalyst is easily restored so that the ozone concentration at the outlet of the catalyst tower does not exceed 0.1 ppm. [Structure] An ozone gas sensor, a heater heater temperature control device, and an indicator for notifying the replacement time of the catalyst were added to the conventional system, and the deterioration of the exhaust ozone gas decomposition catalyst during operation was confirmed in the middle stage of the catalyst layer. The provided ozone gas sensor detects early, and the signal from the ozone gas sensor raises the catalyst layer temperature in increments of + 10 ° C., so that exhaust ozone gas of 0.1 ppm or more is not discharged from the device outlet, and stable for a long period of time. Driving can be continued. Further, the catalyst layer can be partially replaced. When the set temperature of the heater reaches the structural limit temperature of the equipment, the set temperature is not changed and the indicator indicates that it is time to replace the catalyst, and the catalyst is replaced based on this. Maintain stable long-term operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in water treatment facilities such as sewage treatment plants and human waste treatment plants, and is an exhaust ozone gas treatment for decomposing unreacted exhaust ozone gas generated from an ozone reaction tank for ozone treatment. The present invention relates to a device and a method of operating the device.

[0002]

2. Description of the Related Art Water treatment facilities such as water purification plants, sewage treatment plants, and human waste treatment plants are often used in ozone treatment for deodorization, decolorization, iron removal, manganese removal, sterilization, and oxidation of organic substances. There is. This ozone treatment is generally a gas-liquid mixture of ozone and water to be treated in an ozone reaction tank. For ozone treatment, the concentration of 20 g-O ₃ /
Nm ³ ozone is used.

From the ozone reaction tank, the excess ozone produced by the ozone treatment is discharged as exhaust ozone gas. The concentration of ozone in this exhaust ozone gas varies depending on the concentration of injected ozone and the injection rate of ozone, but it is several mg.
The ozone concentration of —O ₃ / L-water is often higher than 1000 ppm. However, this exhaust ozone gas concentration is far higher than 0.1 ppm which is the allowable concentration for occupational health according to the ozone facility design guideline of the Ministry of Health and Welfare, and thus ozone decomposition of the exhaust ozone gas is indispensable.

An exhaust ozone treatment device is used to decompose the exhaust ozone gas into harmless oxygen. Exhaust ozone treatment devices have conventionally used methods such as activated carbon, thermal decomposition, or chemical cleaning, but in recent years, manganese-based exhaust ozone decomposition catalysts are often used from the viewpoint of economy and performance. There is. FIG. 3 is a schematic side view showing a configuration of a main part of a conventional exhaust ozone gas treatment device. Exhaust ozone gas from the ozone reaction tank, which is not shown in FIG. 3, is discharged from the exhaust ozone gas inlet 1 into the first treatment tower (droplet removal tower) of this apparatus.
2 and passes through the mist separator 3 for removing the water mist to be treated entrained in the exhaust ozone gas. Here, the exhaust ozone gas from which the mist has been removed reaches the heating heater 4 which is connected to the pipe, and is heated to the operating temperature of the catalyst, for example, 40 ° C. The exhaust ozone gas heated to a predetermined temperature enters the second treatment tower (catalyst tower) 5 through the pipe, and comes into contact with the manganese-based exhaust ozone gas decomposition catalyst layer 6 filled therein, According to the following reaction, it is decomposed into harmless oxygen and is released from the decomposed gas outlet 7 into the atmosphere.

[0005]

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[0006]

However, the conventional exhaust ozone gas treatment device has the following problems. That is, the exhaust ozone gas treatment apparatus in which the second treatment tower 5 is filled with the manganese-based exhaust ozone gas decomposition catalyst layer 6 has good normal decomposition performance, but in the long term, deterioration of the catalyst and deterioration of the catalyst surface The performance is deteriorated due to the accumulation of impurities, and the ozone concentration at the decomposition gas outlet 7 of the exhaust ozone treatment apparatus is 0.1.
The permissible concentration in ppm may be exceeded.

When the performance deteriorates in this way, exhausted ozone gas exceeding the permissible concentration is released into the atmosphere, which causes a problem in occupational health. Therefore, conventionally, the exhaust ozone gas decomposition catalyst layer 6 is periodically replaced before reaching the end of its service life, or the operation of the exhaust ozone treatment device is temporarily stopped to 500 ° C.
The exhaust ozone decomposition catalyst is heated at around temperature to regenerate and recover,
Exhaust ozone gas is managed so that it does not exceed the permissible concentration of 0.1 ppm for occupational health.

However, periodically exchanging the exhaust ozone gas decomposition catalyst layer 6 before reaching the end of its life will increase the running cost, and when the exhaust ozone gas decomposition catalyst layer 6 is heated at around 500 ° C. Since the second treatment tower 5 containing the exhaust ozone gas decomposition catalyst layer 6 is also heated to that temperature, the second treatment tower 5 itself must have a solid structure so as to withstand the heating. There is also the problem of not becoming.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to easily and easily restore the performance of an exhaust ozone gas decomposition catalyst layer and to provide a second treatment tower filled with the catalyst layer. It is an object of the present invention to provide an exhaust ozone gas treatment device capable of preventing the ozone concentration at the outlet from exceeding an allowable concentration of 0.1 ppm in industrial hygiene and an operating method thereof.

[0010]

The exhaust ozone gas treating apparatus of the present invention is constructed as follows. A mist separator installed in the first treatment tower that removes mist in exhaust ozone gas discharged from the ozone reaction tank of a water treatment device that uses ozone, and a manganese-based exhaust ozone gas decomposition catalyst layer that decomposes and removes exhaust ozone gas A second treatment tower, a heater for heating exhaust ozone gas to a predetermined temperature, which is located in the middle of a pipe connecting the first treatment tower and the second treatment tower, and an exhaust ozone gas decomposition catalyst layer in the middle stage of the second treatment tower. An ozone gas sensor that is installed at the center of the chamber to measure the concentration of exhaust ozone gas, a controller that controls the temperature of the heating heater based on the signal from this ozone gas sensor, an upper heating temperature limit of the second processing tower, and an ozone gas sensor And a display for notifying the replacement time of the exhaust ozone gas decomposition catalyst layer from the signal.

Further, the exhaust ozone gas decomposition catalyst layer can be divided into a plurality of layers in the vertical direction of the second processing tower, and these layers can be stacked and filled. The operating method of this exhaust ozone gas treatment device is performed as follows. When the ozone gas sensor installed in the middle stage of the second processing tower detects an ozone concentration of 0.1 ppm or more, it controls the heating heater and raises the temperature of the exhaust ozone gas decomposition catalyst layer to + 10 ° C from the current set temperature. Then, the operation is continued, and when the ozone gas sensor detects an ozone concentration of 0.1 ppm or more, the heating heater is controlled again to raise the temperature of the catalyst layer to + 10 ° C from the current set temperature. Operate and continue this operating method up to the structural upper temperature limit of the second treatment tower. Then, when the ozone gas sensor detects an ozone concentration of 0.1 ppm or more while continuing the operation at the structural upper temperature limit of the second processing tower, it is displayed that it is the catalyst replacement time.

[0012]

With the above-described device and its operation method, the exhaust ozone gas concentration is detected early by the ozone gas sensor,
Since the catalyst activity is improved by raising the catalyst layer temperature based on the signal, the exhaust ozone gas concentration at the outlet of this device is 0.1 ppm, which is a standard for occupational health.
The stable operation of the exhaust ozone gas treatment device can be performed without exceeding. In addition, even if the catalyst is deteriorated even after such an operation, the deterioration of the catalyst can be detected early by the ozone gas sensor installed in the middle stage of the catalyst layer, and the catalyst can be exchanged from the signal,
The exhaust ozone gas concentration never exceeds 0.1 ppm.

Further, since it is not necessary to regenerate the exhaust ozone gas decomposition catalyst at around 500 ° C. as in the conventional case, the second treatment tower filled with the catalyst layer does not have to have a structure capable of withstanding such a high temperature.

[0014]

EXAMPLES The apparatus of the present invention and its operating method will be described below based on examples. FIG. 1 is a schematic side view showing a configuration of a main part of an exhaust ozone gas treatment apparatus of the present invention, and the same reference numerals are used for the portions common to FIG. 1 is different from FIG. 3 in that the apparatus configuration of FIG. 1 according to the present invention is capable of measuring the exhaust ozone concentration by sampling the exhaust ozone gas from the middle stage of the exhaust ozone gas decomposition catalyst layer 6 and guiding it to the ozone gas sensor 8. The control device 9 for changing the set temperature of the heating heater 4 in response to the signal of the exhaust ozone concentration measured by the ozone gas sensor 8 and the display device 10 for displaying the replacement time of the catalyst layer 6 are added. That is what I did.
In FIG. 1, the connection of the measuring instrument is shown by a solid line and the path of the electric signal is shown by a dotted line.

In FIG. 2, the horizontal axis represents the number of measurements corresponding to the change with time of the operation of this apparatus, and the vertical axis represents the ozone concentration on the decomposition gas outlet 7 side of the catalyst layer 6 and the temperature of the catalyst layer 6. It is a diagram showing a relationship. In FIG. 2, when the performance of the exhaust ozone gas decomposition catalyst layer 6 deteriorates after a certain operation time using the apparatus of the present invention, as shown by the solid curve (a), the middle stage of the second treatment tower 5 is The exhaust ozone gas concentration measured by the provided ozone gas sensor 8 exceeds 0.1 ppm, which is a standard for industrial hygiene, so the controller 9 sets the set temperature of the heating heater 4 to +1 above the preset temperature.
The temperature of the exhaust ozone gas decomposition catalyst layer 6 becomes 50 ° C. as shown by a dotted curve (b) by outputting a signal such that the temperature is set to 0 ° C. and the set value of the heating heater 4 is set to 50 ° C., for example. The exhaust ozone gas concentration which is increased in activity and measured by the ozone gas sensor 8 becomes 0.1 ppm or less, and thereafter, the exhaust ozone gas concentration can be maintained at 0.1 ppm or less until the catalyst is further deteriorated. Further, even at this temperature of 50 ° C., when the exhaust ozone gas concentration measured by the ozone gas sensor 8 exceeds 0.1 ppm, the output from the control device 9 is further set to + 10 ° C., that is, the set value of the heating heater 4 is set to 60 ° C. It may be controlled to do so. However, although the temperature of the heating heater 4 is set to + 10 ° C. as an example here, the temperature increase is not limited to every 10 ° C., and can be set appropriately according to the actual situation.

As described above, according to the exhaust ozone gas treatment apparatus of the present invention, the exhaust ozone concentration at the outlet does not exceed the industrial hygiene standard of 0.1 ppm, and the stable ozone decomposition characteristics are maintained for a long period of time. be able to. Next, the exhaust ozone gas decomposition catalyst layer 6 used to some extent was taken out from the second treatment tower 5 according to the position of the catalyst, and the performance test was carried out. In the test shown in Table 1, the exhaust ozone concentration at the inlet of the catalyst layer 6 is set to 1500 to 1850 ppm, and the decomposition gas outlet 7 of the catalyst layer 6 at each temperature is set.
It is the result of measuring the ozone concentration on the side.

[0017]

[Table 1] As can be seen from the results in Table 1, by increasing the temperature of the catalyst layer, the ozone concentration at the catalyst layer outlet decreased,
Since the catalyst used in the test was a catalyst that had been used at a catalyst layer temperature of 40 ° C. for several years, the catalyst in the upper stage had a catalyst layer temperature of 70
Unless it was set at 0 ° C, the standard for industrial hygiene was not 0.1 ppm.

Further, comparing the performances of the upper, middle, and lower catalysts in the height direction, when the catalyst layer temperature is 40 ° C., the outlet ozone concentration of the upper catalyst is 12.4 ppm. On the other hand, the outlet ozone concentration of the catalyst in the middle stage where the ozone gas sensor 8 is installed is 0.10 ppm, which is the same as the standard for occupational health, and the catalyst in the lower stage is 0.00 ppm.
And ozone is not detected at all.

From the above, by raising the temperature of the catalyst layer 6 by at least 10 ° C. above the preset temperature, the ozone decomposition efficiency becomes 100%, and the exhaust ozone gas treatment device can be operated stably for a long period of time. . Further, from the results of Table 1, even if the upper catalyst is deteriorated, the middle or lower catalyst is less deteriorated than the upper catalyst, and ozone is detected by the ozone gas sensor 8 provided in the middle catalyst. By increasing the temperature of the entire bed, the exhaust ozone gas treatment apparatus can be operated at an outlet of 0.
It can be seen that exhaust ozone gas of 1 ppm or more is not released.

However, since the catalyst layer temperature cannot be raised above the upper temperature limit of the constituent materials of the exhaust ozone gas treatment device, ozone is detected in the middle stage of the catalyst layer, and the catalyst layer temperature at this time is the structure of the exhaust ozone gas treatment device. If it is the upper limit temperature, the display device 10 indicates that it is time to replace the catalyst layer 6 without changing the set temperature of the heating heater 4, and the entire catalyst layer 6 is replaced based on the display. By doing so, the exhaust ozone gas of 0.1 ppm or more, which is the standard for occupational health, is not released from the decomposition gas outlet 7 of the second treatment tower 5.

In addition, the catalyst begins to deteriorate from the inlet side of the catalyst layer 6 into which the exhaust ozone gas flows, and at that time, the middle or lower catalyst is still in a low degree of deterioration. Therefore, the upper catalyst is removed and a new catalyst is used. By replenishing the catalyst that has not deteriorated to the lower stage, it is possible to prevent harmful exhaust ozone gas from leaking from the apparatus and perform stable operation for a long period at the initial set temperature.

Expanding this idea, the exhaust ozone gas decomposition catalyst layer 6 provided in the second processing tower 5 of the exhaust ozone gas processing apparatus of the present invention is divided into a plurality of layers in the vertical direction of the second processing tower 5. It is also possible to stack and install these. By doing this, when exhausted ozone gas is detected, the catalyst layer at the highest position of the catalyst layer 6 is taken out, and the same amount of new catalyst as this catalyst layer is replenished to the catalyst layer at the lowest position. , The same effect can be obtained.

In summary, when operating the exhaust ozone gas treating apparatus of the present invention, the exhaust ozone concentration of the ozone gas sensor 8 inserted in the middle stage of the second processing tower 5, that is, in the central portion of the exhaust ozone gas decomposing catalyst layer 6, is explained. Exceeds 0.1 ppm, a. Raise the set temperature of the heater 4. b. Only the upper part of the catalyst layer 6 is replaced without raising the temperature.

C. When the set temperature reaches the limit, the entire catalyst layer 6 is replaced. Of these, the selection of a or b is preferably determined by the running cost according to the operating status of the device.

[0025]

As described above, according to the exhaust ozone gas treating apparatus and the operating method thereof of the present invention, it is provided in the middle stage of the catalyst layer that the upper exhaust ozone gas catalyst layer is deteriorated by operating for a certain period of time. The ozone gas sensor is used for early detection, and the signal from the ozone gas sensor is used to raise the catalyst layer temperature by + 10 ° C.
From the exit of this device, 0.1pp which is the standard for occupational health
Exhaust ozone gas of m or more does not leak, and stable operation can be continued for a long time.

Further, since the catalyst layer begins to deteriorate from the exhaust ozone gas inflow side, only a part of the catalyst layer, for example, the catalyst in the upper stage is removed, and the same amount of catalyst is replenished in the lower stage, that is, the gas outlet side. The method is also possible, which also has the advantage of reducing the cost of replacing the catalyst. However, when the ozone gas sensor detects exhaust ozone gas of 0.1 ppm or more, and the set temperature of the heating heater reaches the structural limit temperature of the device of the present invention, the set temperature of the heating heater is not changed as it is. In addition, by indicating on the indicator that it is time to replace the catalyst layer, and by replacing the entire catalyst layer based on the display, exhaust ozone gas of 0.1 ppm or more does not leak, and at this time as well, The device can operate stably for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a configuration of main parts of an exhaust ozone gas treatment apparatus of the present invention.

FIG. 2 shows the number of measurements during operation of the device of the present invention on the horizontal axis,
A diagram showing the relationship between the ozone concentration on the gas outlet side of the catalyst layer and the temperature of the catalyst layer on the vertical axis.

FIG. 3 is a schematic side view showing a main configuration of a conventional exhaust ozone gas treatment device.

[Explanation of symbols]

 1 Exhaust Ozone Gas Inlet 2 First Treatment Tower 3 Mist Separator 4 Heater 5 Second Treatment Tower 6 Exhaust Ozone Gas Decomposition Catalyst Layer 7 Decomposition Gas Outlet 8 Ozone Gas Sensor 9 Control Device 10 Display Device

Claims (7)

[Claims] 1. A first method for removing mist in exhaust ozone gas discharged from an ozone reaction tank of a water treatment apparatus using ozone.
Connecting the first treatment tower and the second treatment tower with each other, a second treatment tower filled with a manganese-based waste ozone gas decomposition catalyst layer for decomposing and removing the waste ozone gas, A heating heater located in the middle of the pipe for heating the exhaust ozone gas to a predetermined temperature, and an ozone gas for measuring the concentration of the exhaust ozone gas by inserting the heater into the center of the exhaust ozone gas decomposition catalyst layer in the middle stage of the second processing tower. A sensor, a control device for controlling the temperature of the heating heater based on a signal from the ozone gas sensor, and a replacement of the exhaust ozone gas decomposition catalyst layer based on a heating upper limit temperature of the second processing tower and a signal from the ozone gas sensor. An exhaust ozone gas treatment device comprising a display for indicating the time. 2. A first method for removing mist in exhaust ozone gas discharged from an ozone reaction tank of a water treatment device using ozone.
A mist separator provided in the treatment tower, a second treatment tower in which a manganese-based exhaust ozone gas decomposition catalyst layer for decomposing and removing the exhaust ozone gas is divided into a plurality of layers in the vertical direction and stacked and packed, and the first A heating heater located in the middle of a pipe connecting the processing tower and the second processing tower to heat the exhaust ozone gas to a predetermined temperature, and a central portion of the exhaust ozone gas decomposition catalyst layer stacked in the middle stage of the second processing tower. An ozone gas sensor that is installed in the chamber to measure the concentration of exhaust ozone gas; a control device that controls the temperature of the heating heater based on a signal from the ozone gas sensor; a heating upper limit temperature of the second processing tower; An exhaust ozone gas treatment device, comprising: an indicator for notifying a time of exchanging the exhaust ozone gas decomposition catalyst layer from a signal of an ozone gas sensor. 3. When operating the exhaust ozone gas treatment apparatus according to claim 1, when the concentration of the exhaust ozone gas detected by the ozone gas sensor exceeds 0.1 ppm, the set temperature of the heating heater is set to be higher than the preset temperature. A method for operating an exhaust ozone gas treatment device, characterized in that a signal for enhancing is output from the control device. 4. The method according to claim 3, wherein the preset temperature of the heating heater is indicated as the catalyst replacement time on the display as it is with respect to the structural limit temperature of the second processing tower. Operating method for exhaust ozone gas treatment device. 5. When operating the exhaust ozone gas treatment apparatus according to claim 2, when the concentration of the exhaust ozone gas detected by the ozone gas sensor exceeds 0.1 ppm, the set temperature of the heating heater is set to be higher than the preset temperature. A method for operating an exhaust ozone gas treatment device, characterized in that a signal for enhancing is output from the control device. 6. The method according to claim 5, wherein the preset temperature of the heating heater is indicated as the catalyst replacement time on the display as it is with respect to the structural limit temperature of the second processing tower. Operating method for exhaust ozone gas treatment device. 7. The method according to claim 5, wherein at the time when ozone is detected at the decomposition gas outlet of the second processing tower, the highest catalyst layer is taken out, and the same amount as this catalyst layer is taken out. A method of operating an exhaust ozone gas treatment device, characterized in that a new catalyst is replenished to the lowest catalyst layer.