JP2001079305A - Treatment of pcb-containing oil and treating device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treating method capable of inexpensively and easily decomposing PCB and recovering the treated oil for recycle and the treating device. SOLUTION: In a reaction vessel filled with activated carbon, PCB-containing oil, to which an alkali hydroxide alcohol solution is added, flows into the reaction vessel heated at 300-700 deg.C in an oligoaerobic condition to cause the dechlorination from PCB by the reducing power of the carbon material. The generated chlorine is reacted with the alkali hydroxide into the chloride to make harmless. The solution is neutralized with hydrochloric acid, washed with water, separated and recovered or recycled as the non-polluted oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method and a processing apparatus for detoxifying oil containing harmful polychlorinated biphenyl (hereinafter referred to as "PCB-containing oil").

[0002]

2. Description of the Related Art Polychlorinated biphenyls (hereinafter, referred to as PCBs) are generally very stable in chemicals, and include water, acids,
Not only is it not decomposed by alkali, etc., it is also quite stable thermally and hardly decomposes at quite high temperatures,
It is a substance that hardly decomposes in nature.
On the other hand, PCBs have excellent electrical insulating properties and are very soluble in oil, and thus have been widely used as insulating oil for electric appliances, heating media, copy paper, and the like.

However, PCBs have extremely high toxicity such as carcinogenicity, and when taken into a living body, have the property that they are not discharged outside the body but are accumulated, and it is difficult to treat them as waste. Its use is currently banned as it causes environmental pollution. Then, it is stored in a closed container so as not to leak out.

[0004] PCB-containing oils are used as insulating oils (transformer oil, condenser oil, etc.), or are those in which PCB is mixed with oil, and have a concentration of several ppm to several tens%. I do. As a treatment method for detoxifying PCB which is such a harmful substance, a method of burning at high temperature, a method of decomposing by irradiating ultraviolet rays or radiation in the presence or absence of alkaline alcohol,
A chemical treatment method using metallic sodium, a microorganism treatment method, and the like have been proposed.

[0005]

However, in these conventional treatment methods, depending on the treatment conditions, compounds such as dioxins which are more toxic than PCBs are produced as by-products, treatment costs are too high, and waste treatment is difficult. There was a problem that it was difficult. In addition, in some cases, such as a microorganism treatment method, the decomposition rate is poor and the decomposition is not performed to an allowable level.

What is important in detoxifying PCBs is that no other harmful substances are generated (safety), that the processing steps and reaction conditions are appropriate (economical efficiency of equipment, etc.), and that the safety of equipment is high. And that the sex is sufficient. In addition, it is preferable to establish a method that can easily and reliably remove PCBs from PCB-containing oil, since the PCBs can be collectively made harmless using various methods.

The present invention has been made in view of the above-mentioned points, and it is possible to remove or decompose a PCB easily and inexpensively, and it is possible to collect and reuse the treated oil. An object of the present invention is to provide a method and an apparatus for treating PCB-containing oil.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that when PCB-containing oil is allowed to flow through a filling tank filled with a carbon material, the PCB can be cooled at room temperature. The present inventors have found that it is possible to surely adsorb, and furthermore, it is possible to surely decompose PCB in a heated state, thereby completing the present invention. That is, the invention according to claim 1 provides a filling tank filled with a carbon material with a PC.
By allowing the B-containing oil to flow at room temperature, PC
This is a method for treating a PCB-containing oil in which B is adsorbed on the carbon material.

According to the first aspect of the present invention, since the PCB can be surely adsorbed on the carbon material, the processed oil can be reused. Where the carbon material is
Preferably, it is at least one or more selected from charcoal, charcoal, activated coke and activated carbon, and its shape is preferably at least one selected from granular, fibrous, and the like, and more preferably fibrous activated carbon. . Further, according to the present invention, the chlorine can be reliably desorbed from the PCB by appropriately treating the carbon material on which the PCB is adsorbed. The method of detoxifying the PCB is not particularly limited. For example, as in the invention according to claim 2, the carbon material having the PCB adsorbed thereon is reduced in a reducing atmosphere.
By heating to 00 to 800 ° C., chlorine can be desorbed from the PCB.

The above-mentioned adsorption treatment and desorption treatment do not necessarily have to be independent from each other.
By heating to 800 ° C. and flowing the PCB-containing oil through the reaction tank, chlorine can be desorbed from the PCB. In other words, in the invention according to claim 3 (claim 2), the carbon material such as activated carbon is heated in an oxygen-deficient state or in a reducing atmosphere filled with an inert gas to increase the reducing power of the carbon material. It realizes an effective dechlorination reaction of PCB.

Further, in the invention according to claim 4, the PCB-containing oil to which the alkaline compound or the alkaline solution is added is circulated in the reaction tank, and the chlorine desorbed from the PCB is reacted with the alkaline compound to make it harmless. ing. Here, the alkaline compound is typically an alkali hydroxide, and the alkaline solution is typically an aqueous solution of an alkali hydroxide, an alcohol solution of an alkali hydroxide, or an alcohol solution of an alkali alcoholide. It is. In the present invention, first, PCB contaminated with PCB
An alkaline compound or an alkaline solution is added to and mixed with the contained oil, and the alkaline substance is uniformly dispersed in the PCB-containing oil by dissolving and mixing the alkaline compound. Next, the PCB-containing oil mixed with the alkali compound is circulated in the reaction tank, and is brought into contact with the heated carbon material in a reducing atmosphere such as an oxygen-deficient state (anoxic or poor oxygen) or an inert gas.

The carbon material heated in the reaction vessel has a strong reducing power, and causes a reaction of extracting chlorine from PCB in the PCB-containing oil. That is, the activated carbon material causes a dechlorination reaction from the PCB, resulting in a harmless organic compound containing no chlorine, such as biphenyl. Further, chlorine generated by the decomposition of PCB immediately reacts with an alkali compound to generate an alkali chloride, that is, a salt.

It is also safe to neutralize the chloride salt produced and the alkali added excessively, wash the mixed solution of the decomposed product with water, and remove the chloride salt which is a reaction by-product. Oil can be recovered or reused. That is, after decomposing the PCB, the excess alkali is neutralized with an acid (such as hydrochloric acid), washed with water, and the aqueous solution and the oil are separated.
Since the recovered oil (oil) is below the allowable level of the PCB, it can be reused.

According to the processing method of the present invention, the PCB
Adds an alkaline compound such as an alkaline alcohol to oil contaminated with, and distributes it through a carbon material composed of heated activated carbon to decompose PCB, neutralize and wash, and recover PCB as harmless oil The device can also be implemented. That is, as in the invention according to claim 9,
A reaction tank for heating the charged carbon material to 200 to 800 ° C. in an oxygen-deficient state or a reducing atmosphere filled with an inert gas, a PCB-containing oil to which an alkaline compound or an alkaline solution is added, or a PCB to which these are not added
A recovery tank for recovering the contained oil after circulating it in the reaction tank and performing a neutralization treatment and a washing treatment of the recovered material, and an oil provided downstream of the recovery tank from which PCB is removed and other aqueous solution. And a separation tank for separating the PCB-containing oil. In addition, this device
Because it is a structure that can be loaded on a trailer, PC
The B-containing oil can be processed in a storage place.

FIG. 1 is a schematic configuration diagram of a processing apparatus provided with a mixing tank 1 for mixing an alkaline alcohol and the like with a PCB-containing oil, and includes a mixing tank 1 and a heating unit H such as a heater.
A reaction tank 2 for heating a carbon material such as activated carbon in a reducing atmosphere, a stirring tank 3 for injecting hydrochloric acid or water to neutralize and wash the recovered material from the reaction tank 2, and a stirring tank 3. A separation tank 4 provided on the downstream side is shown. In addition,
An appropriate cooling step is provided between the reaction tank 2 and the stirring tank 3.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the invention according to claim 4, first,
In some cases, an alkaline compound or an alkaline solution is added to and mixed with the PCB-containing oil contaminated with PCB. This treatment realizes a uniform dispersion of the alkaline compound in the PCB-containing oil.

In the present invention, the alkali compound is not particularly limited, but is preferably a hydroxide of an alkali metal or an alcohol solution of an alkali alkoxide. When an alkali metal hydroxide or an alcohol solution of an alkali alkoxide is used, uniform dissolution and dispersion of the alkali in the PCB-containing oil contaminated with PCB is caused, and chlorine generated by dechlorination with activated carbon or the like is converted to alkali. This is because a particularly excellent effect is exhibited in that the reaction is performed uniformly, the decomposed chlorine is removed as chloride, and the generation of harmful by-products due to the decomposed chlorine is prevented.

The concentration of hydroxylation of the alkali metal in the alcohol solution is about 1% by weight or more of the total chlorine concentration, but is preferably 2% by weight to 10% by weight. The alcohol used is a lower alcohol, preferably isopropyl alcohol or ethyl alcohol, and ethyl alcohol is selected from the viewpoint of safety.

The alkali metal hydroxide is a hydroxide of lithium, sodium, potassium and the like, and preferably sodium or potassium hydroxide from the viewpoint of safety. Furthermore, PCBs in PCB-containing oils
If the concentration is high, a potassium hydroxide with high solubility is selected. In the case of high-concentration PCBs, an alcoholic solution of KOH is preferred.

The amount of the alcohol solution of the alkali hydroxide to be used is 1 to 100 times equivalent to the total chlorine concentration of PCB in the PCB-containing oil, which is added to and mixed with the PCB-containing oil. In order to reduce the input amount of hydrochloric acid and the amount of washing with water, it is preferable to add and mix 2 to 10 equivalents.

The heating temperature of the reaction vessel filled with the carbon material is 200 to 800 ° C., preferably 300 to 7 ° C.
00 ° C. Furthermore, in order to keep the reducing power of activated carbon as strong as possible and to prevent consumption of activated carbon,
It should be anoxic or hypoxic and should avoid mixing air as much as possible when injecting the mixture into the reactor, and avoid mixing air into the reactor vessel filled with carbon material. Desirably, an inert gas such as nitrogen gas may be mixed if necessary. In addition, special measures may be taken in order to achieve anoxic or hypoxic condition,
If you prevent the incorporation of air, the hypoxic state will be maintained,
From the viewpoint of simplicity, it is only necessary to prevent air from being mixed.

Although the flow rate of the mixture varies depending on the heating temperature,
The space velocity is preferably 0.01 to 100 / Hr, more preferably 0.1 to 10 / Hr. The carbon material is preferably at least one or more selected from charcoal, charcoal, activated coke and activated carbon, and the form is preferably at least one selected from granular, fibrous, and the like, and more preferably It is fibrous activated carbon.

[0023]

EXAMPLES Next, the present invention will be described with reference to examples, but these are only examples and do not limit the scope of the present invention.

Example 1 A 3% by weight potassium hydroxide / ethanol solution was prepared, and a total chlorine concentration of 1% by weight with respect to a PCB-containing oil containing 1000 ppm of PCB.
Add 0 equivalent of the above ethanol solution and mix well. This mixed solution was flowed at a space velocity of about 1 / Hr into a reaction vessel filled with fibrous activated carbon heated to 400 ° C. A hydrochloric acid solution was added to the solution flowing out of the reaction vessel, neutralized, washed with water, and separated into oil and water. The total PCB concentration in both oil and water was less than 0.1 ppm. Dioxins were not detected.

Example 2 A 3% by weight potassium hydroxide / ethanol solution was prepared, and a total chlorine concentration of 1% by weight with respect to a PCB-containing oil containing 1000 ppm of PCB.
Add 0 equivalent of the ethanol solution and mix well. This mixed solution was flowed at a space velocity of about 0.5 / Hr into a reaction vessel filled with 300 ° C. heated fibrous activated carbon. Add hydrochloric acid solution to the solution flowing out of the reaction vessel,
After neutralization, it was washed with water and separated into oil and water. The total PCB concentration in both oil and water was less than 0.1 ppm.
Dioxins were not detected.

Example 3 A PCB-containing oil containing 1000 ppm of PCB was flowed into a reaction vessel filled with fibrous activated carbon heated to 600 ° C. at a space velocity of about 0.5 / Hr. The solution flowing out of the reaction vessel was neutralized, washed with water, and separated into oil and water. The total PCB concentration in both oil and water was less than 0.1 ppm. Dioxins were not detected. Example 4 A PCB-containing oil containing 1000 ppm of PCB was flowed at a space velocity of approximately 0.5 / Hr into a reaction vessel heated to 400 ° C. and filled with activated carbon having a particle size of 100 to 200 mesh. The solution flowing out of the reaction vessel was neutralized, washed with water, and separated into oil and water. The total PCB concentration in both oil and water was 0.5 ppm. Also,
Dioxins were not detected.

[0027]

According to the treatment method of the present invention, contaminated oil can be recovered as safe oil while being cheap and easy. The recovered oil can be reused or diverted as fuel.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the present invention.

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Claims (9)

[Claims] 1. A method for treating a PCB-containing oil, wherein the PCB-containing oil is allowed to adsorb to the carbon material by flowing the PCB-containing oil at room temperature through a filling tank filled with the carbon material. 2. A PCB-containing oil is allowed to flow through a filling tank filled with a carbon material at room temperature to adsorb the PCB to the carbon material, and the carbon material adsorbed by the PCB is reduced in a reducing atmosphere to 200-200. A method for treating a PCB-containing oil, wherein the PCB is heated to 800 ° C. to remove chlorine from the PCB. 3. A reaction vessel filled with a carbon material is heated to 200 to 800 ° C. in a reducing atmosphere, and a PCB-containing oil is allowed to flow through the reaction vessel to form the P.
A method for treating a PCB-containing oil in which chlorine is desorbed from CB. 4. A reaction vessel filled with a carbon material is heated to 200 to 800 ° C. in a reducing atmosphere, and an alkaline compound or an alkaline solution is added to the reaction vessel.
B-containing oil is passed through the reaction vessel,
A method for treating a PCB-containing oil, wherein chlorine desorbed from the above is made harmless by reacting it with the alkali compound. 5. The processing method according to claim 1, wherein the carbon material is at least one selected from charcoal, charcoal, activated coke, and activated carbon. 6. The alkaline compound according to claim 4, wherein the alkaline compound is an alkaline hydroxide, and the alkaline solution is an aqueous solution of an alkaline hydroxide, an alcohol solution of an alkaline hydroxide, or an alcohol solution of an alkaline alkoxide. Processing method. 7. The processing method according to claim 1, wherein a flow velocity in the reaction tank is a space velocity of 0.01 to 100 / Hr. 8. After reacting chlorine desorbed from PCB with an alkali compound, the reaction product is neutralized by injecting an acid or alkali and washed with water to remove oil from which PCB has been removed. 8. The processing method according to claim 3, wherein the component is separated from the components. 9. Filling the carbon material with reducing atmosphere in a reducing atmosphere
A reaction tank heated to about 800 ° C., a recovery tank that collects PCB-containing oil after flowing through the reaction tank, and performs a neutralization process and a washing process of the recovered material, and is provided downstream of the recovery tank. And a separation tank for separating oil from which PCB has been removed from other components.