JPH09173772A - Operation of waste ozone treating device using active carbon contact method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a waste of active carbon used in a waste ozone treating device and eliminate the danger of the undecomposed waste ozone gas involved by a shortage of contact time discharging, and continuously perform waste ozone treatment. SOLUTION: A first and a second waste ozone treating tower 1, 2 are connected in series or in such a manner that waste ozone is passed through only the waste ozone treating tower on one side by switching operation of four-way switching valves 4, 5. First the waste ozone is passed through the waste ozone treating towers 1, 2 one by one, and when an incineration area 7 reaches the second waste ozone treating tower 2, by switching operation of the switching valve 4, the waste ozone is passed through only the second waste ozone treating tower 2 and active carbon in the first waste ozone treating tower 1 is replaced. And the second and the first waste ozone treating towers are connected in series, and when the incineration area 7 reaches the first waste ozone treating tower 1, the waste ozone is passed through only the first ozone treating tower 1 to replace the active carbon in the second waste ozone treating tower 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating an exhaust ozone treating apparatus for detoxifying exhaust ozone gas generated in various water treatment facilities using ozone by an activated carbon contact method.

[0002]

2. Description of the Related Art In recent years, water pollution of rivers and lakes is advancing along with the deterioration of the water environment in urban areas. Only by combining conventional flocculation and sedimentation, sand filtration and chlorine treatment,
Currently, there are limits to the chromaticity and odor removal effects of raw water for tap water. In particular, about 70% of the water source used as tap water in Japan depends on lake water, dam water, and river water called surface water, and these lake water and dams are actively used for biological activities associated with eutrophication. There is a musty odor or algae odor due to liquefaction.On the other hand, the organic water and ammoniacal nitrogen contained in various effluents flow into the river water, and these influents are completely purified by the natural purification action of the river. It is in a situation where you cannot expect to do it.

Pre-chlorination is generally adopted in order to deal with the deterioration of the water quality of the water source due to such rapid economic growth, but an organic chlorine compound may be generated in the water purification process adopting the pre-chlorination. It is known, and it has a drawback that the mold odor and algae odor of the water source cannot be completely eliminated.

As a countermeasure against this, an ozone treatment or a combined treatment of the ozone treatment and activated carbon treatment is introduced in the operation process of purified water, and sterilization, decolorization, deodorization and harmful substances are made by utilizing the strong oxidizing power of ozone. An advanced water purification system for removing water is being considered.

The above-mentioned ozone treatment is a method utilizing ozone O ₃ which has a much stronger oxidizing power than chlorine, and ozone gas is blown into the water to be treated from the diffuser tube as fine bubbles to form a mixture with the water to be treated. Removal of off-flavor and chromaticity by contact,
Oxidize and remove harmful substances. Exhaust ozone gas that remains unabsorbed in the water to be treated is sent to a separately disposed exhaust ozone treatment device and decomposed to an allowable concentration level or lower so as not to affect the living body. Ozone gas has a strong oxidizing power like fluorine and is harmful to the human body, so it cannot be released into the atmosphere as it is.Therefore, decomposition treatment in the exhaust ozone treatment tower is an essential step. ing.

[0006] In particular, ozone is one of the causative substances of photochemical oxidants. Therefore, the environmental standard regulates the one-hour value to be 0.06 ppm or less, and the working environment standard is 0.1 ppm as an allowable concentration.

[0007] The exhaust ozone treatment method includes an activated carbon contact method, a catalyst method, a thermal decomposition method, a chemical cleaning method, and the like, but the activated carbon contact method and the catalyst method are generally used frequently. The number of processing towers is 1
A method of arranging two processing towers per processing system in parallel and performing alternating operation, or a method of arranging one processing system and one preliminary tower for all processing systems is generally used. .

As shown in the following equations (1) to (3), the decomposition of ozone by activated carbon occurs in addition to the direct reaction between activated carbon and ozone, and the catalytic decomposition on the surface of activated carbon occurs in parallel. .

2O ₃ + 2C → 2CO ₂ + O ₂・ ・ ・ ・ ・ ・ (1) 2O ₃ + C → CO ₂ + 2O ₃・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ ・ (2) 2O ₃ + C → 3O ₂ + C ・ ・ ・ ・ ・ ・ ・ ・ (3) Ozone Assuming that only the above formula (1) is decomposed, 1 g of activated carbon
The amount of ozone that can be decomposed is 4 g, but since the formulas (1) to (3) actually compete with each other, the amount of ozone that can be decomposed by 1 g of activated carbon is 4 to 7 g.

Since the decomposition of ozone by activated carbon is an exothermic reaction, a phenomenon occurs in which the temperature of activated carbon rises by several degrees with the decomposition of ozone. Since the actual exhaust ozone concentration is usually several hundreds to several thousands ppm, there is no possibility of combustion due to the temperature rise of the activated carbon, but aeration of high concentration ozone is not preferable. Generally, activated carbon mixed with silica-alumina is often used so that high-concentration ozone may enter the waste ozone treatment facility, but high-concentration ozone directly supplied from the ozone generator leads to activated carbon. It is necessary to take care not to. When activated carbon mixed with this silica-alumina is used, the amount of ozone capable of decomposing 1 g of activated carbon is about 1 g to 2 g (see Tomio Deguchi, advanced water treatment technology centering on ozone, p160-163).

[0011]

However, the ozone decomposition amount of activated carbon mixed with silica-alumina varies depending on the contact time, the gas superficial velocity, and the like. Normally, the contact time required for the decomposition of ozone is several seconds, but when the exhaust ozone gas has a high concentration, it is necessary to provide a residence time of several tens of seconds in consideration of safety. The above-mentioned gas superficial velocity refers to the amount of exhaust ozone gas processed per fixed area.

However, when the gas superficial velocity is increased, the contact time is shortened and the pressure loss due to activated carbon is increased. A general ozone decomposing device is designed to have a gas superficial velocity of about 300.
˜600 (m / h), and the column size and activated carbon filling amount are determined with a replenishment period of about 3 to 4 months.

The above activated carbon has a high durability, but the filling height in the treatment tower is about 3 meters at maximum, and the ratio [H / D] between the direct line D and the height H of the ozone decomposition tower cross section is usually Since the amount is about 0.8 to 2, the number of exhaust ozone decomposing towers tends to increase when the amount of exhaust ozone is large in a large-scale facility.

Further, as a method of renewing activated carbon, the consumption state can be grasped by observing what is called "ashing" in which the activated carbon changes from black to white by reaction with exhaust ozone gas, so that the ozone treatment is carried out in advance. A monitoring window is installed on the tower to monitor the consumption of activated carbon, and when it is ashed, it is judged that it is time to replace the activated carbon. For example, as shown in FIG. 5, the first exhaust ozone processing tower 1 and the second exhaust ozone processing tower 2 are arranged in parallel, and the switching valves 4, 4 are provided on the inlet side and the outlet side of the exhaust ozone gas 3, respectively.
5, the exhaust ozone gas is sent to either one of the exhaust ozone treatment towers by the switching operation of the switching valves 4 and 5.

In the illustrated example, as shown by the arrow, first, the exhaust ozone gas 3 is fed into the first exhaust ozone treatment tower 1 to
The change of the activated carbon is monitored through the monitoring window 6 installed on the upper side of the waste ozone treatment tower 1, and when a part of the ashing area 7 of the activated carbon appears in the monitoring window 6, the reaction area 8 still remains. However, the switching valves 4 and 5 are immediately switched to switch the operation so that the exhaust ozone gas 3 is sent to the second exhaust ozone processing tower 2, and the unreacted region 9 of the second exhaust ozone processing tower 2 is used. Then, the exhaust ozone gas 3 is decomposed. During this time, the activated carbon filled in the first exhaust ozone treatment tower 1 is exchanged.

A monitoring window 10 is also installed on the upper side of the second exhaust ozone treatment tower 2, and when the change of the activated carbon is monitored and a part of the ashing area 7 appears in the monitoring window 10, the switching valve 4 is immediately set. ，
The operation is switched so that the exhaust ozone gas 3 is sent to the first exhaust ozone treatment tower 1 by performing the switching operation of 5.

Therefore, even if the exhaust ozone gas 3 flowing into the reaction zone 8 remains thick enough to be lowered to a desired concentration or less, the switching operation of the switching valves 4 and 5 is performed in anticipation of safety. Therefore, all of the activated carbon cannot be effectively used. On the contrary, if the operation is continued until the thickness of the reaction zone 8 becomes small, the high concentration exhaust ozone gas 3 may be exhausted without being sufficiently decomposed due to the short contact time. The law inevitably results in waste of activated carbon.

Further, when the switching operation of the switching valves 4 and 5 is carried out, the exhaust ozone gas 3 sent to the first and second exhaust ozone processing towers 1 and 2 must be temporarily stopped, so that the ozone processing apparatus itself. However, there is a problem that the driving must be temporarily stopped.

Therefore, the present invention effectively utilizes all of the activated carbon used in the exhaust ozone treatment device to eliminate the waste of the activated carbon, and the undecomposed exhaust gas is generated due to the short contact time due to the reduction in the thickness of the reaction zone. It is an object of the present invention to provide an operating method that eliminates the possibility of exhausting ozone gas and that can continuously perform exhaust ozone treatment.

[0020]

In order to achieve the above object, the present invention is an exhaust ozone treating apparatus for detoxifying an exhaust ozone gas generated in a water treatment facility by an activated carbon contact method. The first waste ozone treatment tower and the second waste ozone treatment tower are connected in series by a switching operation of a four-way switching valve, or only one waste ozone treatment tower is connected so that waste ozone gas can pass through. When the exhaust ozone gas is sequentially passed through the first and second exhaust ozone treating towers connected in series, and the ashing region in the first exhaust ozone treating tower reaches the second exhaust ozone treating tower, Exhaust ozone gas is allowed to pass only into the second exhaust ozone treatment tower by the switching operation of the four-way switching valve, and at this point, the activated carbon in the first exhaust ozone treatment tower is exchanged, and then the second and first exhaust ozone treatment towers are replaced. Ozone treatment tower in series Continued, and further when the incineration zone of the second exhaust ozone treatment tower has reached the first discharge ozone treatment column,
Operation of the exhaust ozone treatment apparatus using the activated carbon contact method, in which the operation of passing the exhaust ozone gas only in the first exhaust ozone treatment tower and exchanging the activated carbon in the second exhaust ozone treatment tower is repeated Provide a way.

According to this operating method, the ozone gas is decomposed until all the activated carbon in the first or second exhaust ozone treatment tower is in the ashing region, so that all of the activated carbon is effectively used and activated carbon is activated. It is possible to obtain the effect that no waste is generated. Furthermore, since there is no situation in which the operation is continued until the thickness of the activated carbon reaction zone becomes small, there is no possibility that exhaust ozone gas will be discharged without being decomposed due to insufficient contact time, and the first, second The waste ozone treatment tower can be used to continuously perform waste ozone treatment.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an operating method of an exhaust ozone treating apparatus using an activated carbon contacting method according to the present invention will be described below with reference to the drawings. It will be described in detail.

FIG. 1 is a schematic diagram showing the operation pattern of the present embodiment. First, the structure will be described. In the figure, 1 is a first exhaust ozone treatment tower, 2 is a second exhaust ozone treatment tower, Four-way switching valves 4 and 5 are provided on the inlet side and the outlet side of the exhaust ozone gas. Monitoring windows 6 and 10 are installed on the lower portions of the wall surfaces of the first waste ozone treatment tower 1 and the second waste ozone treatment tower 2, respectively.

The exhaust ozone gas 3 first enters the first exhaust ozone processing tower 1 via the four-way switching valve 4, passes through the activated carbon filled in the exhaust ozone processing tower 1, and then switches to the other four-way switching. Return to the four-way switching valve 4 via the valve 5, and then the second
The second exhaust ozone processing tower 2 enters the second exhaust ozone processing tower 2 from below, passes through the activated carbon, and is then released into the atmosphere via the four-way switching valve 5. That is, the first waste ozone treatment tower 1 and the second waste ozone treatment tower 2 are connected in series.

By continuing the decomposition treatment of the exhaust ozone gas 3 in the state of FIG. 1, the ashing area 7 in the first exhaust ozone processing tower 1 gradually expands, and this ashing area 7 passes through the pipe to Two
Reaching below the waste ozone treatment tower 2. Then, the ashing area 7 is observed through the monitoring window 10 installed on the lower side of the second exhaust ozone treatment tower 2. In addition, 8 is a reaction zone observed at the same time in the monitoring window 10, and 9 is an unreacted zone.

When the ashing area 7 is observed in the monitoring window 10 in this manner, the four-way switching valve 4 is set to 9 in the state shown in FIG.
The exhaust ozone gas 3 directly enters the second exhaust ozone treatment tower 2 through the four-way switching valve 4 by rotating the exhaust ozone treatment tower 2 through the four-way switching valve 5 by rotating it by 0 degrees. Are released into the atmosphere. Therefore, since the first exhaust ozone treatment tower 1 is not in use at this time, the activated carbon in the first exhaust ozone treatment tower 1 is exchanged at this time to form the unreacted area 9. .

After exchanging the activated carbon in the first exhaust ozone treatment tower 1, the four-way switching valve 5 is set to 90 as shown in FIG.
When the exhaust ozone gas 3 passes through the second exhaust ozone processing tower 2 and then returns to the four-way switching valve 4 via the four-way switching valve 5, the exhaust ozone gas 3 passes through the second exhaust ozone processing tower 2 and further below the first exhaust ozone processing tower 1. Enters the first exhaust ozone treatment tower 1, passes through the exhaust ozone treatment tower 1, and is then diffused into the atmosphere via the four-way switching valve 5.

Next, in the state of FIG. 3, the second exhaust ozone treatment tower 2
When the ashing area 7 in the inside gradually expands and the ashing area 7 reaches below the first exhaust ozone treatment tower 1, the ashing area 7 is located below the first exhaust ozone treatment tower 1. Window 6 installed in
Observed in. Therefore, as shown in FIG. 4, the four-way switching valve 4
Is rotated by 90 degrees and switched, the exhaust ozone gas 3 directly enters the first exhaust ozone processing tower 1 through the four-way switching valve 4, passes through the exhaust ozone processing tower 1, and then the four-way switching valve 5
It is diffused into the atmosphere through. Therefore, at this point, the second
Since the exhaust ozone treatment tower 2 of No. 2 is not in use, the unreacted area 9 is created by exchanging the activated carbon in the second exhaust ozone treatment tower 2 at this time.

Then, by switching the four-way switching valve 5 again, the state shown in FIG. 1 is restored, and the exhaust ozone gas 3 passes through the first and second exhaust ozone treatment towers 1 and 2 connected in series to the atmosphere. After returning to the operating state of being dissipated, the same operating pattern is repeated.

According to such an operation pattern, as shown in FIG. 1, ozone gas is decomposed until all the activated carbon in the first exhaust ozone treatment tower 1 is in the ashing region 7,
Since all of the activated carbon can be effectively used, there is an effect that the activated carbon is not wasted unlike the conventional parallel operation method (FIG. 5). Further, since the situation where the operation is continued until the thickness of the reaction zone 8 becomes smaller does not occur, there is no fear that the exhaust ozone gas 3 is discharged without being decomposed due to the short contact time.

Further, even when the switching operation of the switching valves 4 and 5 is performed, at least one of the first and second exhaust ozone treatment towers is in an operating state, so that it is not necessary to stop the exhaust ozone gas 3. Therefore, the operation itself of the water treatment facility for ozone treatment is not suspended.

[0032]

As described above in detail, according to the operating method of the exhaust ozone treating apparatus using the activated carbon contacting method according to the present invention, all the activated carbon in the first or second exhaust ozone treating tower is removed. Since the ozone gas can be decomposed until it reaches the ashing region, there is an effect that all of the activated carbon is effectively used and the activated carbon is not wasted.

Further, unlike the conventional case, there is no situation in which the operation is continued until the thickness of the activated carbon reaction zone becomes small. Therefore, the exhaust ozone gas of high concentration is exhausted without being sufficiently decomposed due to the short contact time. There is no fear of being beaten.

Further, even when the switching operation of the switching valve is performed,
Since at least one of the second exhaust ozone treatment towers is in an operating state, there is no need to stop the supply of exhaust ozone gas, and the operation itself of the water treatment facility for performing ozone treatment is not temporarily stopped, Exhaust ozone treatment can be continuously performed using the second exhaust ozone treatment tower.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an operation pattern of an exhaust ozone treating apparatus using an activated carbon contact method according to the present invention.

FIG. 2 is a schematic diagram for explaining an operation pattern following FIG.

FIG. 3 is a schematic diagram for explaining an operation pattern following FIG.

FIG. 4 is a schematic diagram for explaining an operation pattern following FIG.

FIG. 5 is a schematic diagram for explaining an operation pattern of a conventional exhaust ozone treatment apparatus.

[Explanation of Codes] 1 ... First waste ozone treatment tower 2 ... Second waste ozone treatment tower 3 ... Waste ozone gas 4, 5 ... Four-way switching valve 6, 10 ... Monitoring window 7 ... Ashing area 8 ... Reaction area 9 … Unreacted area

Claims (1)

[Claims] 1. An exhaust ozone treatment apparatus for detoxifying exhaust ozone gas generated in a water treatment facility by an activated carbon contact method, comprising a first exhaust ozone treatment tower and a second exhaust ozone treatment tower filled with activated carbon. , The first and second exhaust ozones which are connected in series by switching operation of the four-way switching valve or in which only one exhaust ozone treatment tower is connected so that exhaust ozone gas can pass and the exhaust ozone gas is initially connected in series. When the ashing area in the first exhaust ozone processing tower reaches the second exhaust ozone processing tower by sequentially passing through the processing towers, the exhaust ozone gas is changed to the second exhaust ozone processing by the switching operation of the four-way switching valve. The activated carbon in the first exhaust ozone treatment tower is replaced at this point, and then the second and first exhaust ozone treatment towers are connected in series, and the second exhaust ozone treatment is further performed. The ashing area in the tower is the first When it reaches the ozone treatment tower, the exhaust ozone gas is passed only through the inside of the first exhaust ozone treatment tower, and the operation of exchanging the activated carbon inside the second exhaust ozone treatment tower is repeated. And a method for operating an exhaust ozone treatment apparatus using the activated carbon contact method.