JP2753106B2 - Waste ozonolysis equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an apparatus for decomposing exhausted ozone gas.

(Prior art) In the water treatment field such as a water treatment plant, a sewage treatment plant, a human waste treatment plant, etc., ozone is used for the purpose of deodorization, decolorization, iron removal, manganese removal, disinfection, and oxidation of organic substances. Ozone treatment utilizing strong oxidizing power has been widely put to practical use.

In this ozone treatment, ozonized air having an ozone concentration of 20 g ozone / Nm ³ -air is generally used in view of the operation efficiency of the ozone generator. From the ozone reaction tank in which ozonized air and non-treated water are mixed in a gas-liquid state, surplus ozonized air due to the ozone reaction is discharged as exhausted ozone gas.

The concentration of exhausted ozone gas varies depending on the non-treated water, the purpose of the ozone reaction, the ozone concentration of ozonized air, the injection rate of ozonized air, etc., but 1000 ppm (VOl / VOl) at an ozone injection rate of several mg ozone / water. Exhaust ozone concentration often exceeds. This concentration is much higher than the allowable concentration for occupational health in the Ozone Facility Guidelines of the Ministry of Health and Welfare, which is much higher than 0.1 ppm.

In general, an exhaust ozone decomposing device that decomposes this exhaust ozone gas uses a decomposing tower filled with activated carbon.

However, since activated carbon is consumed over time, replacement is necessary, and the replacement operation is troublesome. Some of them have a device for regenerating activated carbon, but there is a drawback that the device becomes large.

Therefore, in recent years, an exhaust ozone decomposing apparatus in which a manganese-based exhaust ozone decomposing catalyst having better performance than activated carbon is filled in a decomposition tower has been used in many cases. This waste ozone decomposer is used by heating and maintaining the temperature at about 40 ° C. in order to prevent the catalyst from being wetted by the water contained in the waste ozone.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional exhaust ozone decomposing apparatus filled with a manganese-based catalyst, the normal decomposition performance is good, but the allowable concentration exceeds 0.1 ppm due to temporary decomposition failure. There is an empirical fact that it is repeated, and stabilization of decomposition performance has been desired.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a temporary decomposition failure of a waste ozone decomposing device and to stabilize and improve decomposition performance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, an exhaust ozone decomposing apparatus according to claim (1) is configured to be filled with an exhaust ozone decomposing catalyst and capable of heating and keeping heat. Cracking tower, an ozone meter for measuring the ozone concentration of the exhaust gas collected from the downstream side in the cracking tower, and temperature control for automatically setting the heating and keeping temperature of the cracking tower in a plurality of stages according to the measured ozone concentration. And a container.

Further, the exhaust ozone decomposition apparatus according to claim (2) is capable of heating and maintaining the temperature by filling the first ozone decomposition catalyst filled with the exhaust ozone decomposition catalyst and capable of heating and maintaining the temperature and by filling the exhaust ozone decomposition catalyst. A second decomposition tower that takes in the exhaust gas of the first decomposition tower via a connection part, an ozone meter that measures the ozone concentration of the exhaust gas collected from the connection part, Depending on the concentration, the first decomposition tower or /
And a temperature controller for automatically setting the heating / retaining temperature of the second decomposition tower in a plurality of stages.

(Operation) Experimental characteristics of the decomposition tower, which is a premise of the operation of the present invention, will be described with reference to FIG.

FIG. 4 is an experimental characteristic diagram in which a decomposition tower is filled with a manganese-based waste ozone decomposition catalyst, the temperature of the decomposition tower is maintained at 40 ° C., and the ozone air introduced into the decomposition tower has an ozone concentration of 1000 ppm (humidity 90%). .

In this experiment, gas sampling ports were installed at 30% and 70% of the height of the decomposition tower to measure the ozone concentration in order to examine the distribution of ozone concentration in the decomposition tower. The ozone concentration at the bottom and top of the decomposition tower height on the horizontal axis was measured at the inlet and outlet of the decomposition tower, respectively. The 0.1 ppm of the ozone concentration on the vertical axis is a reference value for judging the quality of waste ozone decomposition.

Characteristic A indicates a case where the decomposition characteristics of the decomposition tower are normal. In the characteristic A, it can be seen that the ozone concentration is 0 with a margin in the decomposition tower.

The property B is satisfactory because the ozone concentration at the outlet of the decomposition tower is 0, but the margin is small in view of the height of the decomposition tower.

Characteristic C is a value when the waste ozone decomposition performance is at an allowable limit value, and characteristic D is a result when exhaust gas ozone decomposition failure occurs completely.

When viewed over time, it was observed that the characteristic change of B → C → D → C → B was repeated on a daily basis within a time width of several hours, although the characteristic A was mostly maintained.

In order to solve this exhausted ozone decomposition failure, when this decomposition failure occurs, the temperature for heating and keeping the decomposition tower set from 40 ° C to 10 ° C
The characteristic of increasing in units of ° C. was examined. As a result, an immediate effect appears when the set temperature rises by about 10 ° C., and characteristics B, C,
It was found that D returned to characteristic A.

FIG. 5 shows the relationship between the temperature rise from the set temperature of 40 ° C. and the recovery time from the characteristic D to the characteristic A.

As shown in the figure, it was found that the higher the temperature, the shorter the recovery time and the higher the effect.

Based on the above findings, the ozone concentration on the downstream side of the gas in the decomposition tower was measured as shown in claim (1), and the characteristic B indicating the microscopic signs of poor ozone decomposition was appropriately grasped. By switching the temperature to a predetermined recovery set temperature, it becomes possible to prevent defective exhaust ozone decomposition.

Also, according to the set temperature increase, if the recovery of the degradation of the exhausted ozone decomposition catalyst is actively applied, the size of the decomposition tower can be designed to be the minimum and an efficient decomposition tower can be manufactured.

On the other hand, when raising the set temperature, the temperature rising speed until reaching the rising temperature is particularly important for shortening the recovery time of the exhaust ozone decomposition catalyst and improving the reliability of performance.

In the case of using the same volume of exhausted ozone decomposition catalyst, the decomposition tower is made smaller and the number of towers is increased, the temperature rise speed is faster and the recovery time is shorter. FIG. 6 shows this relationship.

As shown in the figure, with the same volume of exhaust ozone decomposing catalyst, the smaller decomposing tower divided into two towers, compared to the one-column type, has a shorter heating time until the temperature rises, and can respond quickly. You can see that you can do it. That is, it is apparent that the recovery time to the characteristic A in FIG. 4 is shorter in the two-tower type.

Based on the above findings, the concentration of ozone collected from the connection portion of the splitting tower divided into two as described in claim (2) was measured, and the above-mentioned characteristic B, which is a sign of poor ozone decomposition failure, was properly grasped. By switching from the set temperature of ° C. to the predetermined recovery set temperature, it becomes possible to prevent the exhaust ozone decomposition failure beforehand.

Generally, 300 to 4 exhaust ozone decomposition catalysts that have become poorly decomposed
Although regeneration treatment is performed at a high temperature of 00 ° C., in each of the inventions described in claims (1) and (2), the initial stage of exhaust ozonolysis failure is properly grasped, and recovery is performed by the initial deterioration of the exhaust ozonolysis catalyst. By setting the temperature to a low temperature of 100 ° C. or lower, it is possible to prevent the decomposition of waste ozone from occurring.

(Embodiment) FIG. 1 is a configuration diagram of an embodiment of the present invention.

A support member 2 made of a stainless steel wire mesh or the like is provided below the inside of the decomposition tower 1, and a manganese-based exhaust ozone decomposition catalyst 3 is filled on the support member 2. The exhaust ozone decomposition catalyst 3 is generally in the form of a pellet having a diameter of about 1 to 2 mm and a length of about 2 to 3 mm.

A gas sampling member 4 for measuring the ozone concentration is disposed downstream of the packed bed of the exhausted ozone decomposition catalyst 3. The pipe connected to the gas sampling member 4 goes out of the decomposition tower and is connected to the ozone meter 6 via the automatic on-off valve 5. Gas sampling member 4
The piping from to the ozone meter 6 is required by the ozone meter 6
Use a stainless steel tube with an inner diameter of about 4 mm that matches the gas flow rate of ~ 2 / min.

The tip portion of the gas sampling member 4 may be any material that can prevent the broken waste of the exhaust ozone decomposition catalyst 3 from blocking the gas sampling port, and a stainless steel mesh filter or a sintered filter can be used. In addition, if the gas sampling member 4 is integrated with a flange that can be easily removed and is attached to and supported by the disassembly tower 1, periodic inspection is facilitated.

The exhaust ozone gas introduced from the lower end of the decomposition tower 1 passes through the support member 2 and the exhaust ozone decomposition catalyst 3 and is discharged from the exhaust gas pipe 7 as exhaust gas containing almost no ozone gas.

An automatic on-off valve 8 is connected to a pipe branched from the exhaust gas pipe 7, and a pipe exiting the automatic on-off valve 8 is connected to an outlet pipe of the automatic on-off valve 5 and connected to an ozone meter 6.

The ozone meter 6 measures the ozone concentration of two systems connected to the automatic opening / closing valves 5 and 8 by automatically switching the automatic opening / closing valves 5 and 8 by a built-in flow path switch. The system of the automatic opening / closing valve 8 is for monitoring that the exhaust gas is exhaust gas and has a concentration of 0.1 ppm or less. The system of the automatic opening / closing valve 5 is for grasping a slight deterioration of the exhaust ozone decomposition catalyst 3. The amount of the ozone concentration to be set as the level of the deterioration may vary depending on the filling conditions of the exhaust ozone decomposition catalyst 3, the operating conditions, the mounting height position of the gas sampling member 4, and the like. In this case, the ozone concentration of about 0.1 to 0.4 ppm can be regarded as a weak sign of deterioration. Therefore, the measurement range of the ozone meter 6 is set to 0 to 0.5 ppm or 0 to 1 p.
If it is used as pm, the above two systems ozone concentration measurement is 1
This is possible with a single ozone system 6.

Note that the two measurement gases introduced into the ozone meter 6 are:
Since it is heated to about 40 ° C., an ozone meter 6 having a dehumidifying mechanism such as an electronic cooler is used in order to prevent an indication error due to dew condensation in the ozone meter 6. Further, the outlet gas of the ozone meter 6 may exceed 0.1 pm in the case of the measurement of the system of the automatic on-off valve 5, so that the ozone meter 6 filled with activated carbon or the like may be used.
It is necessary to incorporate a small ozone decomposer for use.

The outer surface of the decomposition tower 1 is covered with a heating and heat retaining member 9. The heating and heat retaining member 9 is generally made of an electric heater and an outer covering material. The electric heater has a capacity capable of heating and maintaining the temperature of the exhausted ozone decomposition catalyst 3 in the decomposition tower 1 from about 40 ° C. to about 100 ° C.

A temperature sensor 10 for measuring the temperature of the exhausted ozone decomposition catalyst 3 is provided on the gas upstream side of the decomposition tower 1. The signal of the temperature sensor 10 is input to the temperature controller 11, and when the exhaust ozone decomposition performance of the decomposition tower 1 is normal, the temperature of the exhaust ozone decomposition catalyst 3 becomes
It is operated at a normal set temperature of about 40 ° C.

The temperature controller 11 is provided with a function of inputting the ozone concentration output of the ozone meter 6 and automatically selecting a set temperature of the exhaust ozone decomposition catalyst 3 in a plurality of stages in accordance with the ozone concentration output. Table 1 shows a specific example.

The combination of the ozone concentration output and the set temperature can be freely set because the appropriate value is determined by the structure of the decomposition tower 1 including the mounting position of the gas sampling member 4 and the operating conditions. Is desirable.

Next, comparing the driving effect of the present embodiment with the conventional one,
As shown in FIG. This is a comparison of representative examples showing exhausted ozone decomposition failure from long-term operation data of the decomposition tower 1.

As shown in the figure, in the conventional example, the pass / fail judgment reference value is 0.1 p.
There are characteristics that greatly exceed pm over a long period of time. On the other hand, according to the present example, there is no time zone exceeding 0.1 ppm, and it can be seen that stable operation is continued and defective ozone decomposition is prevented in advance.

 FIG. 3 is a block diagram of another embodiment of the present invention.

In the present embodiment, two decomposition towers in which the exhaust ozone decomposition catalyst is divided at a volume ratio of 1: 1 are installed, and a support made of a stainless steel mesh or the like is provided below the decomposition towers 21 and 22. Members 23 and 24 are provided, and manganese-based exhaust ozone decomposition catalysts 25 and 26 are filled on the support members 23 and 24.

Connecting pipe between decomposition tower 21 and decomposition tower 22 (with ribbon heater, etc.)
A gas sampling member 28 for the exhaust gas of the decomposition tower 21 is provided in the middle of 27 (heated and kept at about 40 ° C.). The pipe connected to the gas sampling member 28 is connected to an ozone meter 30 via an automatic on-off valve 29.

The exhausted ozone gas introduced from the lower end of the decomposition tower 21
Decomposition tower 22 through supporting member 23 of 21 and exhaust ozone decomposition catalyst 25
To, introduced from the lower end in the same manner as the decomposition tower 21, the support member 24,
The exhaust gas is discharged from the exhaust gas pipe 31 via the exhaust ozone decomposition catalyst 26.

The pipe exiting the automatic on-off valve 32 connected to the pipe branched from the exhaust gas pipe 31 is combined with the outlet of the automatic on-off valve 29 and connected to the ozone meter 30.

The ozone meter 30 measures the two systems of ozone concentration connected to the automatic open / close valves 29 and 32 by automatically switching the automatic open / close valves 29 and 32 with a built-in flow path switch. The system of the automatic opening and closing valve 32 is an exhaust gas and is for monitoring that the concentration is below the allowable concentration of 0.1 ppm, but the system of the automatic opening and closing valve 29 is for catching the slight signs of deterioration of the exhaust ozone decomposition catalyst 25. .

The outer surfaces of the decomposition tower 21 and the decomposition tower 22 are covered with heating and heat retaining members 33 and 34, respectively. The heat insulation members 33 and 34 are generally made of an electric heater and an outer covering material. The electric heater is a decomposition tower
21, the capacity of the exhaust ozone decomposition catalysts 25 and 26 in the decomposition tower 22 is set to a temperature capable of heating and maintaining the temperature up to about 40 ° C.

Temperature measurement sensors 35, 36 for measuring the temperature of the exhaust ozone catalysts 25, 26
Is installed on the gas upstream side of the decomposition tower 21 and the decomposition tower 22.
The signals from the temperature measuring sensors 35 and 36 are input to the two-system temperature controller 37, and when the exhaust ozonolysis performance of the decomposition towers 21 and 22 is normal, the temperature of the exhaust ozonolysis catalysts 25 and 26 is about 40 ° C. It is operated at the normal set temperature. The temperature controller 37 is provided with a function of inputting the ozone concentration output of the ozone meter 30 and automatically setting the set temperatures of the exhaust ozone decomposition catalysts 25 and 26 in a plurality of stages in accordance with the ozone concentration output.

According to the present embodiment configured as described above, as shown in FIG. 2, it was confirmed that defective ozone decomposition was prevented beforehand as in the previous embodiment.

Further, in the present embodiment, the exhausted ozone gas rises to a predetermined temperature by heating and maintaining the temperature of the decomposition tower 21, flows into the decomposition tower 22, and
Support 22 heat insulation. Therefore, during the season when the outside air temperature is high, such as in the spring to summer, the thermal insulation of the decomposition tower 21 is mainly performed, and the thermal insulation of the decomposition tower 22 may be stopped. Therefore, there is an advantage that the energy consumption of the electric heater of the decomposition tower 22 can be saved.

In addition, an ozone meter 30 for measuring the weakness of exhaust ozone decomposition failure
Since the gas sampling member 28 connected to the gas is provided on the way of the connecting pipe 27 between the decomposition tower 21 and the decomposition tower 22, the ozone concentration in the non-measurement gas is mixed and averaged, and the ozone concentration can be measured stably. In addition, there is an advantage that the structure of the gas sampling member 28 can be easily maintained.

As can be seen from FIG. 4, the volume ratio of the exhausted ozone decomposition catalyst in the decomposition tower 21 and the decomposition tower 22 can be not 1: 1, but 2: 1, 3: 1, etc. It is necessary to design in accordance with the actual situation in consideration of ascertaining the signs of deterioration of the catalyst earlier, increasing the speed of raising the temperature of the exhausted ozone decomposition catalyst, and reducing the heating and holding energy of the exhausted ozone decomposition catalyst. it can.

In each of the above embodiments, the automatic on-off valves 5 and 8 or 29 and 32 for measuring the exhaust gas concentration and the ozone concentration from the gas sampling member 4 or 28 with one ozone meter 6 or 30 are used. If each ozone concentration is set to a dedicated ozone meter, the automatic switching valves 5 and 8 or 29 and 32 and the ozone meter 6 or 30 with a built-in flow path switch are not required.

The automatic opening / closing valves 5 and 8 or 29 and 32 can be replaced with one three-way valve. In addition, a flow control valve for making the gas flow of the two systems introduced into the ozone meter 6 or 30 the same must be naturally incorporated at the time of design.

In each of the above embodiments, the temperature controller 11 or 37 automatically selects the set temperature of the exhausted ozone decomposition catalyst 3 or 25 or 26 in a plurality of steps based on the ozone concentration output of the ozone meter 6 or 30. Alternatively, the set temperature can be automatically selected by using a contact output such as an alarm contact corresponding to the ozone concentration output of 30.

Further, in each of the above embodiments, the heating and heat retaining member 8 or 3
Although the electric heater is used as the heating source for the heating units 3, 34, the heating source is not limited to this, and a heating medium that can adjust the temperature, such as hot water or hot oil, may be used. However, the waste ozone decomposition catalyst 3 or 25,26
In order to promptly respond to the weakness of the deterioration of the material, it is preferable to use a material having a high temperature rising speed and a large heat capacity.

Further, the present invention is not limited to a manganese-based exhaust ozone decomposition catalyst, but can be applied to an iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ) catalyst, a platinum catalyst tower, and other exhaust ozone decomposition catalysts.

[Effects of the Invention] As described above, according to the present invention, the deterioration of the exhaust ozone decomposition catalyst can be detected before the deterioration of the exhaust ozone decomposition catalyst becomes large. Deterioration can be prevented promptly and in a low temperature range of 100 ° C or less, which greatly contributes to the improvement of the performance of decomposition towers and energy and labor savings.

Furthermore, it is possible to reduce the amount of the exhausted ozone decomposition catalyst to be filled in the decomposition tower to near the limit value, and it is possible to realize the miniaturization of the decomposition tower.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a characteristic diagram for explaining the characteristics of the present invention shown in FIGS. 1 and 3 in comparison with a conventional example, and FIG. FIG. 4 to FIG. 6 are configuration diagrams of another embodiment and are experimental characteristic diagrams for explaining the operation of the present invention. 1,21,22… Decomposition tower 3,25,26… Exhaust gas decomposition catalyst 4,28… Gas sampling member 6,30… Ozone meter 11,37… Temperature controller

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Tanaka, Inventor 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. (56) References JP-A-3-135418 (JP, A) JP-A-2- 298317 (JP, A)

Claims (2)

(57) [Claims] 1. A decomposition tower filled with an exhausted ozone decomposition catalyst and capable of heating and keeping heat, an ozone meter for measuring the ozone concentration of exhaust gas collected from a downstream side in the decomposition tower, A temperature controller capable of automatically setting a heating and keeping temperature of the decomposition tower in a plurality of stages in accordance with a concentration; 2. A first decomposition tower filled with an exhausted ozone decomposition catalyst and capable of heating and maintaining the temperature, and a first decomposition tower filled with an exhausted ozone decomposition catalyst and capable of heating and maintaining the temperature. A second decomposition tower that takes in the exhaust gas of the decomposition tower through a connection, an ozone meter that measures the ozone concentration of the exhaust gas collected from the connection, and the first decomposition that is performed in accordance with the measured ozone concentration. A temperature controller capable of automatically setting the heating and keeping temperature of the tower or / and the second decomposition tower in a plurality of stages;