JPH06277679A - Cleaning method for wet oxidization device - Google Patents

Abstract

PURPOSE:To remove solid matters such as scales or sediments generated inside a wet oxidization device and clean a catalyst, an adsorption material, a filler and the like attached to a reactor. CONSTITUTION:A wet oxidization device is cleaned under the pressure in which cleaning liquid retains the liquid phase containing sodium hydroxide and/or potassium hydroxide at a temperature of 50 deg.C-300 deg.C in the cleaning method for the wet oxidization device. It is preferable to clean the wet oxidization device under the supply of a gas containing oxygen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a wet oxidation reactor, or a catalyst attached to the reactor by removing solid matter such as scale or sediment generated inside a wet oxidation treatment apparatus.
The present invention relates to a method for cleaning adsorbents, fillers and the like. More specifically, from various industrial plants such as a chemical plant having a high chemical oxygen demand (hereinafter also referred to as “COD”), food processing equipment, metal processing equipment, metal plating equipment, printing plate making equipment, semiconductor manufacturing equipment, etc. When purifying the discharged wastewater by the wet oxidation method, solid matter such as scale or sediment generated inside the wet oxidation treatment device is removed,
Wet oxidation treatment device or catalyst attached to it, adsorbent,
The present invention relates to a method for cleaning a filling material and the like.

[0002]

2. Description of the Related Art In a conventional wet oxidation method, waste water containing heavy metals, aluminum, phosphorus, silicon, calcium, magnesium and other scale-prone components (hereinafter also referred to as scale-forming substances) was wet-oxidized. In this case, there is a problem that scale adheres to the heat exchanger, the reaction tower, the catalyst, the adsorbent, the filler, etc., or the solid matter accumulates. Therefore, various methods, for example, (i) a method of adding additives or the like to wastewater to make it difficult to generate scale, (ii) a system such as an apparatus improved to make it difficult to attach scale,
ii) A method of removing scale-forming substances in wastewater by pretreatment to prevent scale formation, and (iv) a method of removing adhered scale using a cleaning agent or the like have been implemented or proposed.

[0003]

When the above methods (i) to (iii) are used, for example, there are the following problems, and any of the methods requires improvement for them, and is It is insufficient to solve the above problems. (i) The method of adding an additive is effective for a specific scale-forming substance, but less effective for most other scale-forming substances. (ii) The method of solving by improving the system such as the device has the problem of equipment cost, space, etc., and it is generally difficult to carry out.Also, even if an effective method is adopted, the above problems are completely solved. I can't solve it. (iii)
In the method of removing the scale-forming substance by the pretreatment, a great amount of pretreatment is required to remove all the various scale-forming substances, and it is difficult to remove it sufficiently. Therefore, the merit of treating the wastewater by the wet oxidation treatment method is reduced.

Therefore, for the wet oxidation treatment, it is essential to use the method (iv) to wash the wet oxidation treatment apparatus or the catalyst, adsorbent, filler, etc. attached thereto. However, in the method using the detergent proposed hitherto, it is not possible to widely exert the effect on various scale-forming substances, and it is limited to a specific scale-forming substance. This is not sufficient because there is a generation of substances that cause pollution and there is a problem in the corrosion resistance of the material of the device.

The object of the present invention is to solve the above-mentioned problems, that is, it is effective at a wide variety of scale producing substances at low cost without producing substances that cause secondary pollution, and there is a problem in the corrosion resistance of equipment materials. The present invention proposes a method of cleaning a wet oxidation treatment apparatus or a catalyst, an adsorbent, a filler, etc. attached to the apparatus.

[0006]

As a result of earnest research to solve the above problems, the present inventor has found that a wet oxidation treatment apparatus is washed with an aqueous sodium hydroxide solution and / or an aqueous potassium hydroxide solution. A method for cleaning the wet oxidation treatment apparatus, which is characterized by easy operation and excellent practicability and economy. The present invention is specified as follows.

(1) Cleaning a wet oxidation treatment apparatus with a cleaning liquid containing sodium hydroxide and / or potassium hydroxide under a pressure that maintains the liquid phase at a temperature of 50 ° C. to 300 ° C. A characteristic method for cleaning a wet oxidation treatment apparatus.

(2) The cleaning method according to the above 1, wherein the wet oxidation treatment apparatus is cleaned while supplying a gas containing oxygen.

(3) The cleaning method as described in 1 or 2 above, wherein the wet oxidation treatment apparatus incorporating at least one of a catalyst, an adsorbent and a filler is washed.

(4) Heavy metals, silicon, aluminum,
The above 1 to 3 for cleaning the wet oxidation treatment apparatus on which a solid substance containing at least one selected from the group consisting of phosphorus, calcium or magnesium is adsorbed and / or attached.
The described cleaning method.

The concentration of the aqueous solution of sodium hydroxide and / or the aqueous solution of potassium hydroxide (hereinafter, also referred to as "washing liquid") according to the present invention may be any concentration within a range that can be usually used, but an aqueous solution of sodium hydroxide is preferable. (NaO
H concentration standard) and / or potassium hydroxide aqueous solution (KOH
It is effective that the concentration is 1 g / liter or more, and more preferably 10 g / liter or more. Concentration of NaOH and / or KOH is 1g
If it is less than 1 liter / liter, the cleaning effect is significantly reduced. If the amount is less than 10 g / liter, the amount of the cleaning liquid is large, the treatment after cleaning becomes complicated, and the treatment temperature needs to be relatively high in order to complete the cleaning treatment in a short time. The effect is slightly inferior.

The total concentration of NaOH and / or KOH is preferably less than 400 g / liter, more preferably less than 300 g / liter. Four
When it is more than 00 g / liter, the viscosity of the cleaning liquid increases, making it difficult to feed the cleaning liquid, and the corrosion resistance of the equipment material deteriorates when used at high temperatures.

If the above-mentioned concentration is within the above-mentioned range, it can be appropriately changed and used within the allowable range of the equipment of the wet oxidation treatment equipment.

When the cleaning solution of the present invention is compared with an aqueous solution of sodium hydroxide and an aqueous solution of potassium hydroxide under the same concentration and under the same conditions, no significant difference in cleaning power can be found. Aqueous sodium solution is more effective.

Further, when it is desired to perform washing under milder conditions due to the material of the reactor, sodium carbonate and / or potassium carbonate can be used instead of sodium hydroxide and / or potassium hydroxide. . Lithium hydroxide, cesium hydroxide or rubidium hydroxide can also be used, but it is not practical due to cost problems.

In the present invention, the solid matter such as scale or sediment to be cleaned is not particularly limited, but for example, heavy metals such as chromium, copper, nickel, cobalt, manganese, other aluminum, phosphorus, silicon. ,
It is effective for a scale or a solid substance containing at least one selected from the group consisting of calcium and magnesium as a main component, and more effective is a solid substance containing aluminum, phosphorus and silicon as a main component. Further, the solid substance containing at least one of aluminum, phosphorus, and silicon as the main components has higher detergency as compared with the case where a conventional acidic cleaning liquid such as a nitric acid aqueous solution is used.

However, with respect to the solid matter containing iron as a main component, the structure of iron is stabilized as diiron trioxide, which makes it difficult to wash and remove the solid matter. The cleaning method can be used after confirming that the iron content is low.

The washing temperature in the present invention is not particularly limited as long as it is a temperature range in which washing can be performed normally, but is preferably 50 ° C to 300 ° C, more preferably 130 ° C to 270 ° C. When the cleaning temperature is low, the substantial cleaning effect is small, and when the processing temperature is high, the cleaning time is shortened and the cleaning power is improved, but it is necessary to perform cleaning at a temperature at which the cleaning liquid holds the liquid phase. In addition,
The treatment temperature is high, and NaOH or K of the cleaning solution is used.
When the OH concentration is high, the corrosion resistance of the material of the device is lowered.

The treatment pressure according to the present invention is appropriately selected according to the correlation with the treatment temperature, and is performed under the pressure at which the cleaning liquid holds the liquid phase.

The wet oxidation treatment apparatus to be washed in the present invention is not particularly limited as long as it is necessary for treatment of waste water in a normal wet oxidation treatment, and it may be a pressurizing section or a normal pressure section, a high temperature section. It is not particularly limited as to whether it is a part or a room temperature part. Further, the wet oxidation reaction tower may be of a type used as an empty tower without being filled in the reaction tower, or a type in which the catalyst described below is filled and the catalyst is wet-oxidized. It may be one. The wet oxidation reaction tower may be filled with a filler such as metal or ceramic to improve stirring of liquid and gas, or an adsorbent such as ceramic may be filled. However, the scale-generating substance or the like may be adsorbed and removed. The wet oxidation reaction tower may be of a single tube type or a multi-tube type. Also, although not particularly limited, the cleaning treatment in the present invention is particularly effective, such as equipment of wet oxidation treatment equipment, lines, structures, catalysts in wet oxidation treatment equipment among packings,
This is for packing materials such as adsorbents and packing materials.

The material of the wet oxidation treatment apparatus to be cleaned in the present invention is not particularly limited as long as it is a material that is normally used. For example, titanium, titanium-palladium, zirconium, SUS, Hastelloy (registered trademark). ,
Although it is vinyl chloride, polyethylene, Teflon (registered trademark), etc., it is effective in titanium, titanium-palladium, zirconium, and Hastelloy (registered trademark). PVC, polyethylene, and the like cause a decrease in the strength of the material at high temperatures, and thus need to be washed at low temperatures.

Even if the above-mentioned wet oxidation treatment apparatus is filled with a catalyst, it can be treated without any problem. The catalyst is usually used for wet oxidation treatment, and is particularly a solid catalyst, which has both activity and durability under the conditions of liquid phase oxidation, and does not deteriorate the catalyst by the cleaning method of the present invention. Any catalyst may be used as long as it is one, for example, a catalyst containing titanium, iron, aluminum, silicon, zirconium or activated carbon, and preferably titanium, titanium-zirconium, or titanium-
An oxide such as iron. These catalysts may contain a second component in addition to the above components (hereinafter also referred to as the first component).

The second component is at least one metal such as manganese, cobalt, nickel, tungsten, copper, cerium, silver, platinum, palladium, rhodium, gold, iridium or ruthenium, or a component thereof. Can be used. This catalyst preferably accounts for 75 to 99.95% by weight of the first component and 25 to 0.05% by weight of the second component.
In addition, various shapes of the catalyst can be adopted and are not particularly limited.

Further, even if the above-mentioned wet oxidation treatment apparatus is filled with the filler, it can be treated without any problem. The filler is intended to be usually used for wet oxidation treatment, and is not particularly limited as long as it is particularly made of metal or ceramic, but for example, titanium, titanium-palladium, zirconium, etc. are made of metal. It is effective. If it is made of ceramics, for example, titanium,
Oxides containing iron, aluminum, silicon, zirconium and the like are mentioned, and oxides such as titanium, titanium-zirconium and titanium-iron are preferable. Also,
As the shape of the filler, various shapes can be adopted and are not particularly limited.

Further, even if the wet oxidation treatment apparatus is filled with an adsorbent, it can be treated without any problem. The adsorbent is intended to be one that is usually used for wet oxidation treatment, and is not particularly limited as long as it is made of ceramic, but for example, an oxide containing titanium, iron, aluminum, silicon, zirconium, etc. It is effective to use an oxide such as titanium, titanium-zirconium, or titanium-iron. Further, various shapes can be adopted as the shape of the adsorbent, and the shape is not particularly limited.

The oxygen-containing gas used for cleaning in the present invention is a gas containing oxygen, air or ozone. When a gas such as ozone or oxygen is used, it is appropriately diluted with an inert gas before use. be able to. In addition to these gases, oxygen-containing waste gas generated from other plants can also be used as appropriate. The amount of this gas used is not particularly limited, but when cleaning the metal material portion, it is effective that the amount is at least an amount that forms an oxide film of the material. This is because when the amount is less than the amount of forming an oxide film of the material, there may be a problem in the corrosion resistance of the material due to cleaning. Therefore, considering the above, the oxygen concentration in the oxygen-containing gas (in the case of O ₃ etc., the oxygen equivalent concentration) is 5 to 100%, preferably 10% to 30%.

The method of feeding this gas is not particularly limited. For example, it may be fed from a gas insertion line used for treating wastewater in a normal wet oxidation treatment operation, or it may be fed separately. Of the sodium hydroxide washing liquid of the present invention, and may be fed in a gas-liquid mixed state.

The main cleaning treatment may be carried out for a time that can be usually carried out, but is preferably 1 hour to 48 hours.
The time is more preferably 2 hours to 24 hours, and if it is less than 1 hour, the cleaning is slightly unsuccessful, and if it exceeds 48 hours, the time for cleaning is too long, This is not preferable because the time required for the original wet oxidation treatment is reduced.

The cleaning method according to the present invention may be a continuous cleaning method in which the cleaning liquid is always flowed, or a batch method in which the cleaning solution is stored in a wet oxidation treatment apparatus and left standing for a certain time for cleaning, and is withdrawn as needed. The cleaning method may be the same.

The position where the cleaning liquid is inserted into the wet oxidation treatment apparatus may be fed from a wastewater insertion line used for treating wastewater in a normal wet oxidation treatment operation, or from another line. It may be fed, and is not particularly limited.

The amount of the cleaning liquid used for cleaning is not particularly limited because it greatly changes depending on the cleaning conditions, but generally it is from 1 time the internal volume of the wet oxidation treatment apparatus to be cleaned. The amount is preferably about 20 times, more preferably 3 to 15 times. In addition, the space velocity (LH
SV) is preferably 0.01~100h ~ ^1, more preferably from 0.1 to 10 ~ ^1. As an example, in the cleaning method by continuous operation processing, the space velocity (LH
SV) = 1 h to ¹ for about 1 to 20 hours. Also, if washed in batch mode, once to 20 times
The cleaning operation is repeated about once, and one operation is 1
It will be retained for about an hour.

The flow direction of the cleaning liquid in the wet oxidation reaction tower or the heat exchanger during the cleaning is
The flow direction may be the same as or opposite to the flow direction of the waste water flowing when the waste water is treated in the normal wet oxidation treatment operation, but the opposite direction is more effective. Further, in the case of batch-type cleaning, the cleaning liquid may be inserted into the wet oxidation treatment device and may be extracted in the same direction, or in the opposite direction, but the same liquid direction is preferable. More effective.

Next, the position at which the cleaning liquid is withdrawn from the wet oxidation treatment device after cleaning the wet oxidation treatment device may be from the wastewater withdrawal line used for treating the wastewater in the normal wet oxidation treatment operation, It may be extracted from another line, and in the case of a batch type cleaning method, the position where the cleaning liquid is inserted and the position where the cleaning liquid is extracted may be the same.

The treatment liquid of the washing liquid used may be directly discharged after performing pH adjustment and solid-liquid separation operation as a post-treatment, and may be subjected to biological treatment or chemical treatment as necessary. You can also

The acid added to adjust the pH is not particularly limited, and various acids such as hydrochloric acid and sulfuric acid which are commonly used can be used.

Similarly, the solid-liquid separation operation performed as a post-treatment is not particularly limited and can be appropriately performed by using a commonly used solid-liquid separation processing apparatus. As the solid-liquid separation treatment device, various devices such as a sedimentation separation treatment device, a centrifugal separation treatment device, or a filtration separation treatment device can be adopted. At this time, if necessary, a flocculant, a flocculation aid, a filter aid, or the like may be added to increase the processing speed and the separation efficiency. As the coagulant, coagulant aid or filter aid, various conventional coagulants can be used and are not particularly limited.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0038]

【Example】

(Example 1) Using the wet oxidation treatment apparatus shown in FIG.
Wet oxidation treatment was performed continuously for 50 hours. And 15
The solid substance obtained after 0 hour was used for the continuous washing for 6 hours in the present invention. The detailed experimental methods and results are described below.

As a detailed method of the wet oxidation treatment, the waste water sent from the waste water supply line 7 was pressure fed to the waste water supply pump 2 at a flow rate of 1 liter / hr to 75 kg / cm ² G. On the other hand, the air supplied from the oxygen-containing gas supply line 8 is pressurized by the compressor 3 and then O ₂ / CO
D (Cr) (oxygen amount in air / chemical oxygen demand amount) = 2.
It was mixed in the wastewater at a ratio of 0. This gas-liquid mixture is introduced from the lower part into a wet oxidation reaction column filled with a titania adsorbent through a gas-liquid mixture supply line 9 and heated by an electric heater 4 to be wet-oxidized at a processing temperature of 250 ° C. to be treated liquid. Is cooled in the cooler 5 via the treatment liquid line 10,
It flowed to the gas-liquid separator 6. In the gas-liquid separator 6, the liquid level controller (LC) detects the liquid level to operate the liquid level control valve 12 to maintain a constant liquid level, and the pressure controller (PC) detects the pressure. The processing liquid is discharged from the liquid discharge line 13 by operating the pressure control valve 14 to maintain a constant pressure. In addition, the property of the wastewater used for the treatment is that silicon is 850 mg.
/ Liter.

After the wet oxidation, a large amount of solid matter was attached to the surface of the titania adsorbent filled in the wet oxidation reaction tower. As a result of analysis with an electron probe microanalyzer, it was found that the main component was silicon.

Subsequently, the titania adsorbent having the solid matter adhered thereto was used to perform the cleaning in the present invention using the same wet oxidation reaction treatment apparatus.

A detailed method of this cleaning treatment is as follows: The cleaning liquid of 100 g / liter sodium hydroxide aqueous solution sent from the waste water supply line 7 is 75 kg / cm ² G at a flow rate of 0.5 liter / hr by the waste water supply pump 2. It was boosted with. On the other hand, the air supplied from the oxygen-containing gas supply line 8 was mixed into the cleaning liquid at 0.05 Nm ³ / h. This gas-liquid mixture is passed through the gas-liquid mixture supply line 9,
It is introduced into the wet oxidation reaction tower (empty tower) from the bottom, heated by an electric heater 4 and washed at a washing treatment temperature of 250 ° C., and the liquid to be washed is cooled in a cooler 5 through a treatment liquid line 10 and discharged. It was discharged from line 13.

As a result, the solid matter adhering to the surface of the titania adsorbent filled in the wet oxidation reaction tower could be almost removed.

Therefore, the wet oxidation treatment of the waste water described above was continuously performed under the same conditions, and the washing treatment of the present invention was again performed twice under the same conditions as above. As a result, the wet oxidation treatment device was operated without blockage, and solid matters were not particularly adhered to the surface of the titania adsorbent after washing.

Example 2 Using the wet oxidation treatment apparatus shown in FIG. 1, the same procedure as in Example 1 was repeated except that the waste water and the adsorbent were changed as follows.
The wet oxidation treatment was continuously performed for 50 hours.

The property of the waste water used for the wet oxidation treatment was 150 mg / liter of aluminum. Further, after the above wet oxidation using a composite oxide of titanium-zirconium as the adsorbent, solid matter was attached to the surface of the adsorbent filled in the above wet oxidation reaction tower. As a result of analysis with an electron probe microanalyzer, it was found that aluminum was the main component.

Thereafter, using this adsorbent having a solid substance attached thereto, the washing treatment of the present invention was performed under the same conditions as in Example 1 except for the following, using the same wet oxidation treatment apparatus as described above. As for the condition of the cleaning treatment, a 200 g / liter aqueous potassium hydroxide solution was used as the cleaning liquid, and the cleaning treatment temperature was 200 ° C. The pressure of the cleaning treatment was 50 kg / cm ² G. The cleaning treatment was performed for 8 hours.

As a result, the solid matter adhering to the surface of the titanium-zirconium composite oxide adsorbent filled in the wet oxidation reaction tower could be almost removed.

Therefore, the wet oxidation treatment of the waste water described above was continuously performed under the same conditions, and the washing treatment of the present invention was again performed twice under the same conditions as above. As a result, the wet oxidation treatment device was operated without blockage, and no solid matter was particularly attached to the surface of the titanium-zirconium composite oxide adsorbent after washing.

(Example 3) Example 1 was repeated except that the wet oxidation treatment apparatus shown in FIG. 1 was used and the waste water was changed to the following.
By the same operation as above, wet oxidation treatment was continuously performed for 150 hours.

The property of the wastewater used for the wet oxidation treatment was 90 mg / liter of phosphorus.

After the wet oxidation, solid matter was attached to the surface of the adsorbent filled in the wet oxidation reaction tower. As a result of analysis with an electron probe microanalyzer, it was found that phosphorus was the main component.

Thereafter, using this adsorbent having a solid substance attached thereto, the washing treatment of the present invention was performed under the same conditions as in Example 1 except for the following, using the same wet oxidation treatment apparatus as described above. The conditions for the cleaning treatment were that a 250 g / liter sodium hydroxide aqueous solution was used as the cleaning liquid, and the cleaning treatment temperature was 160 ° C. The cleaning treatment pressure was 9 kg / cm ² G, and the air feed rate was 0.3 Nm ³ / h. The cleaning process is 20
I went on time.

As a result, the solid matter adhering to the surface of the titania adsorbent filled in the wet oxidation reaction tower could be almost removed.

Therefore, the wet oxidation treatment of the waste water described above was continuously performed under the same conditions, and the washing treatment of the present invention was again performed twice under the same conditions as above. As a result, the wet oxidation treatment device was operated without blockage, and solid matters were not particularly adhered to the surface of the titania adsorbent after washing.

Example 4 In Example 1, no air was mixed in during the cleaning treatment, the sodium hydroxide concentration was 20 g / liter, and the cleaning temperature was 180 ° C.
The same procedure as in Example 1 was performed, except that the cleaning time was 40 hours. The solid matter adhering to the surface of the titania adsorbent before the cleaning treatment was almost the same as in Example 1.
Could be removed as well.

The reason why the conditions are changed as described above is that if oxygen is not mixed in the cleaning liquid, the wet oxidation treatment device may be corroded, and as a result, the cleaning conditions can be made mild. It turns out that it can be washed sufficiently.

Example 5 The procedure of Example 1 was repeated, except that the amount of sodium hydroxide was changed to 100 g / liter of potassium hydroxide.

The solid matter adhering to the surface of the titania adsorbent before the cleaning treatment could be removed in substantially the same manner as in Example 1.

(Comparative Example 1) A wet oxidation treatment was performed under the same conditions as described in Example 1 except that the cleaning treatment according to the present invention was not performed and the continuous wet oxidation treatment was performed.

As a result, after about 250 hours, the portion filled with the adsorbent in the reaction tower was clogged and the wet oxidation treatment could not be performed. After that, the wet oxidation reaction tower was opened, and the titania adsorbent filled therein was taken out. As a result, solid matter adhered to the surface of the titania adsorbent and a large amount of solid matter was filled in the gaps.
As a result of analysis with an electron probe microanalyzer, it was found that the main component was silicon.

(Comparative Example 2) In Example 2, except that after the wet oxidation treatment for 150 hours, the washing treatment with the potassium hydroxide washing solution according to the present invention was not carried out in the washing treatment, but the washing treatment was carried out with water. The wet oxidation treatment and the washing treatment were performed under the same conditions as those described in Example 2.

The result was that after about 380 hours, the portion filled with the adsorbent for the reaction tower was clogged and the wet oxidation treatment could not be performed. After that, the wet oxidation reaction tower was opened, and the adsorbent of the titanium-zirconium composite oxide filled therein was taken out. As a result, solid matter adhered to the surface of the adsorbent and a large amount of solid matter was filled in the gaps. As a result of analysis with an electron probe microanalyzer, it was found that aluminum was the main component.

(Comparative Example 3) Wet oxidation treatment and cleaning treatment were carried out under the same conditions as described in Example 1 except that the cleaning treatment temperature in Example 1 was 25 ° C.

As a result, after about 280 hours, the portion filled with the adsorbent for the reaction tower was clogged and the wet oxidation treatment could not be performed. After that, the wet oxidation reaction tower was opened, and the titania adsorbent filled therein was taken out. As a result, solid matter adhered to the surface of the titania adsorbent and a large amount of solid matter was filled in the gaps.
As a result of analysis with an electron probe microanalyzer, it was found that the main component was silicon.

Comparative Example 4 Wet oxidation treatment and washing under the same conditions as in Example 1 except that 100 g / liter nitric acid aqueous solution was used instead of sodium hydroxide aqueous solution in the washing treatment. Processed.

The obtained results show that during the test, the wet oxidation treatment could be carried out without blocking the filling portion of the adsorbent for the reaction tower. After that, the wet oxidation reaction tower was opened and the titania filled therein was filled. When the adsorbent was taken out, solid matter adhered to the surface of the titania adsorbent, and a large amount of solid matter was clogged in the gaps. As a result of analysis with an electron probe microanalyzer, it was found that the main component was silicon. Further, there is a problem that NOx is generated in the exhaust gas during the cleaning process.

[Brief description of drawings]

FIG. 1 is one of embodiments of a processing apparatus according to the present invention.

[Explanation of symbols]

 1. Wet oxidation reaction tower 2. Waste water (cleaning liquid) supply pump 3. Compressor 4. Electric heater 5. Cooler 6. Gas-liquid separator 7. Waste water (cleaning liquid) supply line 8. Oxygen-containing gas supply line 9. Gas-liquid mixture supply line 10. Processing liquid line 11. Cooling water line 12. Liquid level control valve 13. Liquid discharge line 14. Pressure control valve 15. Exhaust gas discharge line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehiro Takashima 1 of 992 Nishioki, Okihama, Aboshi-ku, Himeji-shi, Hyogo Prefecture Nippon Shokubai Himeji Manufacturing Co., Ltd.

Claims (4)

[Claims] 1. A wet oxidation treatment apparatus is washed with a cleaning liquid containing sodium hydroxide and / or potassium hydroxide under a pressure that maintains a liquid phase at a temperature of 50 ° C. to 300 ° C. And a method for cleaning a wet oxidation treatment device. 2. The cleaning method according to claim 1, wherein the wet oxidation treatment apparatus is cleaned while supplying a gas containing oxygen. 3. The wet oxidation treatment apparatus incorporating at least one of a catalyst, an adsorbent and a filler is washed.
Or the cleaning method described in 2. 4. The wet oxidation treatment apparatus to which the solid substance containing at least one selected from the group consisting of heavy metals, silicon, aluminum, phosphorus, calcium or magnesium is adsorbed and / or adhered is washed.
The described cleaning method.