JP2002059145A - Decomposition treatment method for hardly decomposable organic compounds - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To remove PCBs and the like from electric members and render them harmless, and to disassemble and recover the collected PCBs and the like efficiently and at low cost. SOLUTION: An electric member 1 containing a hardly decomposable organic compound such as PCB is heated under reduced pressure to evaporate and remove the hardly decomposable organic compound. Decomposes by irradiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hardly decomposable organic compound such as a PCB (polychlorinated biphenyl) which is hardly decomposable by removing the hardly decomposable organic compound from an electric member such as a transformer or a capacitor. The present invention relates to a method for decomposing organic compounds.

[0002]

2. Description of the Related Art In Japan, techniques for detoxifying insoluble organic compounds such as PCB and dioxin have been developed. In particular, various instructions and regulations are given to the manufacture, import, use, etc. of PCBs, and it is mandatory for users to strictly store and manage electrical members such as capacitors and transformers in which PCBs are used. But,
Continuation of storage and management of electrical components including PCBs involves not only safety risks but also economic difficulties, and it is desired to establish safe treatment methods from the viewpoint of environmental safety and economic effects. ing. In addition, these electric members are made of precious resources such as copper and iron, and from the viewpoint of reuse, it is possible to remove PCBs adhered or impregnated by safe processing methods to make the electric members harmless. Is desired.

Under such circumstances, a method has been proposed in which after removing oil from a transformer on a power distribution pole, PCBs or the like are evaporated and recovered by vacuum heating (JP-A-9-192534).
And JP-A-9-192535). In addition, a method has been proposed in which a transformer or a capacitor containing PCB or the like is heated in vacuum without removing oil to evaporate and collect the PCB or the like (see JP-A-11-309222).

[0004]

However, since each of the above-described methods for removing PCBs and the like completely removes PCBs and the like from electrical members and renders the electrical members harmless, the collected P
CB or the like must be separately rendered harmless by chemical treatment or the like. For this reason, in addition to the vacuum heating device, equipment for a decomposition processing apparatus such as a PCB is required, and the equipment cost is enormous. In addition, since the vacuum heating device and the decomposition treatment device are separate equipment, separate safety equipment is required to ensure the safety of the surrounding environment, and investment in safety equipment is enormous. Become.

Further, even if the vacuum heating apparatus and the decomposition processing apparatus are simply installed at the same location, it is necessary to cool and recover the PCB and the like evaporated by the vacuum heating method once and then introduce the same into the decomposition processing apparatus. And work efficiency is not good.

Accordingly, the present invention is to provide a method for decomposing a hardly decomposable organic compound, which can remove PCBs and the like from electrical members to make them harmless and can decompose collected PCBs and the like efficiently and at low cost. Aim.

[0007]

In order to achieve the above object, a method for decomposing a hardly decomposable organic compound according to the present invention comprises heating an electric member containing the hardly decomposable organic compound under reduced pressure. The decomposable organic compound is removed by evaporation, and the evaporated and hardly decomposable organic compound removed by evaporation is decomposed by electron beam irradiation.

Accordingly, electric members such as transformers and capacitors containing a hardly decomposable organic compound such as PCB are heated under reduced pressure (hereinafter referred to as "vacuum heat treatment") to evaporate the hardly decomposable organic compound. In addition, the hardly decomposable organic compound can be removed from the electric member. Since the evaporated hardly decomposable organic compound is decomposed by irradiating an electron beam in a gaseous state, the hardly decomposable organic compound recovered from the electric member is cooled as in the conventional case and a separate decomposer is used. Can be disassembled without being transferred to Therefore, the removal of the hardly decomposable organic compound from the electric member and the decomposition treatment of the hardly decomposable organic compound can be performed efficiently and inexpensively.

According to a second aspect of the present invention, in the method for decomposing a hardly decomposable organic compound according to the first aspect, the heating of the electric member is performed in an atmosphere of 100 mbar or less. Here, if the atmosphere exceeds 100 mbar, the evaporation of the hardly decomposable organic compound is not performed well, and the decomposition efficiency with respect to the processing cost is deteriorated. Therefore, when the atmosphere is set to 100 mbar or less, the evaporation of the hardly decomposable organic compound can be favorably performed by heating. In this specification, “vacuum” means not only a complete vacuum (0 mbar) but also a concept including an atmosphere reduced in pressure from the atmospheric pressure.

[0010] Further, the invention according to claim 3 is based on claim 1.
Alternatively, in the method for decomposing a hardly decomposable organic compound described in 2, the electric member is heated at 100 to 650 ° C. Here, when the heating of the electric member is set to less than 100 ° C., the hardly decomposable organic compound is not sufficiently evaporated. If the heating of the electric member is made to exceed 650 ° C., the heat efficiency is low and the heating furnace needs to have high durability, which is not practical. Therefore, when the heating temperature of the electric member is set to 100 to 650 ° C., the evaporation of the hardly decomposable organic compound can be performed best and efficiently.

According to a fourth aspect of the present invention, in the method for decomposing a hardly decomposable organic compound according to any one of the first to third aspects, the decomposition of the hardly decomposable organic compound by irradiation with an electron beam is 100 mbar or less. It is done in an atmosphere. Here, when the atmosphere exceeds 100 mbar, the decomposition of the hardly decomposable organic compound is not performed well, and the decomposition efficiency with respect to the processing cost is deteriorated. Therefore, when the atmosphere is 100 mbar or less, the decomposition of the hardly decomposable organic compound can be favorably performed.

On the other hand, in the method for decomposing a hardly decomposable organic compound according to claim 5, the electric member in its original form is subjected to a process for removing the hardly decomposable organic compound, and then the treated electric member is disassembled to remove metal. And a member made of plastics or the like is treated as a hardly decomposable material, and the remaining member made of paper or wood is hardly decomposed by the method of any one of claims 1 to 4. Organic compounds are removed and decomposed. In this case, it is possible to satisfactorily remove the hardly decomposable organic compound even from a member made of paper or wood from which it is relatively difficult to remove the hardly decomposable organic compound, and efficiently and inexpensively perform the decomposition treatment of the hardly decomposable organic compound. become able to.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings. In the first embodiment of the method for decomposing a hardly decomposable organic compound of the present invention, an electric member containing a hardly decomposable organic compound such as PCB is heated under reduced pressure to evaporate and remove the hardly decomposable organic compound,
The gaseous hardly decomposable organic compound removed by evaporation is decomposed by electron beam irradiation. For this reason, since the evaporated hardly decomposable organic compound is directly decomposed by electron beam irradiation, the hardly decomposable organic compound recovered from the electric member is once cooled and transferred to a separate decomposer as in the conventional case. Decomposition processing can be performed without causing the decomposition. Therefore, it becomes possible to efficiently and inexpensively remove and detoxify the hard-to-decompose organic compound from the electrical member.

The hardly decomposable organic compound used herein is PCB
And its derivatives, dioxins, hardly decomposable organic compounds such as pesticides (DDT and defoliants), and oils containing these compounds. The term “electric member” is a concept including electric equipment such as a transformer and a capacitor containing a hardly decomposable organic compound and articles contaminated with the hardly decomposable organic compound.

The heating of the electric member is preferably performed in an atmosphere of 100 mbar or less. Atmosphere is 10
If it exceeds 0 mbar, the evaporation efficiency with respect to the processing cost will be deteriorated.
By setting the ratio to ar or less, the heat evaporation of the hardly decomposable organic compound can be favorably performed.

In the vacuum heating atmosphere of the electric member, the degree of vacuum does not increase so much during the evaporation of the hardly decomposable organic compound, and the degree of vacuum increases after the evaporation is completed. However, in practice, if the pressure is reduced below 0.01 mbar, enormous energy and large-scale equipment are required. Therefore, from the viewpoint of cost and efficiency, it is preferable that the degree of vacuum be at most about 0.01 mbar.

Here, the average boiling point of PCB and insulating oil at normal pressure is about 350 ° C., and the maximum boiling point at this time is about 450 ° C. This is about 120 ° C. when converted to a vacuum (0.05 mbar) state. Therefore, even if vacuum heating of the electric member is performed at a temperature lower than 100 ° C., the effect is low and it is not practical. Further, it is not practical to heat the electric member in an atmosphere exceeding 650 ° C. because the heat efficiency is low and the heating furnace needs to have high durability. Therefore, the heating of the electric member is preferably performed at 100 to 650 ° C.

Further, the heat treatment of the electric member is 250 to 40.
More preferably, it is performed at 0 ° C. Under these conditions, for example, a condition of 400 ° C. at a degree of vacuum of 100 mbar corresponds to about 530 ° C. of normal pressure, so that the PCB can be sufficiently heated to the maximum boiling point of normal pressure (about 450 ° C.). It becomes possible to evaporate and heat high-concentration PCBs used for other than the upper transformer. Moreover, within this temperature range, the paper, wood or plastic of the electrical member is carbonized,
A more preferable heat treatment can be realized from the viewpoint of heat efficiency and evaporation treatment.

The term “electron beam irradiation” includes a general concept of irradiating electrons to decompose a hardly decomposable organic compound, and also includes a discharge phenomenon such as arc discharge or corona discharge. By this electron beam irradiation, the hardly decomposable organic compound can be decomposed and converted into a harmless substance. Here, this decomposition treatment method is not limited to completely decomposing the hardly decomposable organic compound by electron beam irradiation to render it harmless, but it may be changed to a low chlorinated product by decomposition. In this case, the operation of the electron beam irradiation can be effectively utilized as a pretreatment for facilitating the application of the chemical treatment method defined in the waste treatment method.

Decomposition by electron beam irradiation is 100 mb
It is preferably performed in an atmosphere of ar or less. If the atmosphere exceeds 100 mbar, the decomposition efficiency with respect to the processing cost deteriorates.
The decomposition of the hardly decomposable organic compound can be performed most preferably by setting the pressure to 00 mbar or less. Actually, if the pressure is reduced to less than 0.01 mbar, enormous energy and large-scale equipment are required. Therefore, from the viewpoint of cost and efficiency, the degree of vacuum is at most 0.01 mbar.
It is preferably about ar.

The hardly decomposable organic compound is detoxified by decomposition. If necessary, the detoxified gaseous hardly decomposable organic compound is cooled and condensed by a vacuum condenser or a vacuum oil shower or the like. You may make it collect | recover and remove completely.

Further, since the vacuum heating process and the electron beam irradiation are performed under reduced pressure, exhaust gas is generated. It is preferable that the exhaust gas is cleaned by an exhaust gas safety system such as an activated carbon adsorption device to surely prevent environmental pollution. .

The conditions for producing dioxins include a predetermined amount of oxygen, chlorine, a benzene ring,
Although a temperature of 0 ° C. or higher is required, according to the decomposition treatment method of this embodiment, since heating and electron beam irradiation are performed in an oxygen-free state under vacuum, the generation of dioxins can be prevented. it can. That is, PCB irradiation by electron beam irradiation
Even if chlorine generated by the decomposition of the compound reacts with the decomposition product of PCB, no dioxins are generated because the oxygen concentration is low.

Next, a second embodiment of a method for decomposing a hardly decomposable organic compound will be described. In this decomposition treatment method, the electric member in its original form is subjected to a removal treatment of a hardly decomposable organic compound, and thereafter, the treated electric member is disassembled. The removal method here is not limited to the vacuum heat treatment, but may be a method such as solvent washing defined by the waste treatment method. Then, the member made of metal or plastic is treated as a hardly decomposable material, and the hardly decomposable organic compound is removed from the remaining member made of paper or wood by the decomposition method of the first embodiment described above. Decompose.

In this case, the removal of the hardly decomposable organic compound can be satisfactorily performed even on a member made of paper or wood from which it is relatively difficult to remove the hardly decomposable organic compound. Will be able to do it.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention. For example, in the present embodiment, the electron beam irradiation is performed under reduced pressure, but is not limited to this, and may be performed in an atmosphere of atmospheric pressure. Also in this case, a gaseous hardly decomposable organic compound can be decomposed by an electron beam.

The temperature and pressure at which the vacuum heating is performed and the pressure at which the electron beam irradiation is performed are not limited to the above-mentioned range.

[0028]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

FIG. 1 is a flow chart showing a treatment process and an apparatus in one embodiment of the method for decomposing a hardly decomposable organic compound of the present invention. The apparatus of this embodiment includes a vacuum heating facility 2 for heating an electric member 1 under reduced pressure, an electron beam irradiation facility 3 for decomposing gaseous hardly decomposable organic compounds, and cooling a product obtained by decomposition. A recovery facility 4 for recovery and an exhaust safety measure 5 for ensuring the detoxification of the exhaust from the vacuum system are provided.

The vacuum heating equipment 2 is a vacuum heating furnace, and includes a furnace 6 and a heater (not shown) for heating the inside of the furnace 6.
And a vacuum pump 7 for reducing the pressure inside the furnace body 6. As a heating method using a heater, any of direct heating by an internal heater, indirect heating by an external heater, high-frequency heating, electromagnetic induction heating, and the like may be used. In short, the electric member 1 is heated to a predetermined temperature. I just want it. The vacuum pump 7 is connected to the vacuum heating equipment 2 via the electron beam irradiation equipment 3 and the recovery equipment 4. Therefore, by operating the vacuum pump 7, the vacuum system including the vacuum heating equipment 2, the electron beam irradiation equipment 3, and the recovery equipment 4 is depressurized and maintained in a vacuum state.

The electric member 1 installed inside the furnace body 6
Heated by a heater under reduced pressure. Thereby, the hardly decomposable organic compound (for example, PC
The insulating oil containing B) is evaporated and removed from the electric member 1.

The electron beam irradiation equipment 3 irradiates the atoms and molecules of the hardly decomposable organic compound flowing in the vacuum state from the vacuum heating equipment 2 toward the vacuum pump 7 with an electron beam. As a result, the hardly decomposable organic compound is decomposed into a harmless substance by dechlorination or destruction of the molecular structure. As electron beam irradiation,
For example, corona discharge or arc discharge can be used.

The recovery equipment 4 is a vacuum condenser or a vacuum oil shower, or a combination thereof. The recovery facility 4 cools, condenses and recovers the decomposed and detoxified product by the electron beam irradiation facility 3 in a vacuum state. Further, the substance recovered by the recovery facility 4 is returned to normal pressure and then processed by an appropriate method as needed.

The exhaust gas safety equipment 5 is provided with, for example, a dust filter and an activated carbon adsorbing section for collecting the exhaust gas passing therethrough. The exhaust gas from the vacuum pump 7 is a cracked gas mainly composed of air contained in the vacuum system and light hydrocarbons decomposed by vacuum heating. Although this decomposed gas does not contain a hardly decomposable organic compound and is harmless, it is purified by passing through the exhaust safety device 5 and then released to the atmosphere, so that further safety to the environment is ensured. can do.

Using the equipment having the configuration shown in FIG. 1 described above, a decomposition / recovery experiment of a hardly decomposable organic compound was conducted according to the method for decomposing a hardly decomposable organic compound of the present invention.

A container as the electric member 1 containing the insulating oil containing PCB was set in the vacuum heating equipment 2, and the inside of the furnace body 6 was depressurized by operating the vacuum pump 7. And the inside of the furnace body 6 is 1 m
When the pressure was reduced to about bar, heating by the heater and electron beam irradiation in the electron beam irradiation equipment 3 were started.

Here, the evaporation temperature of the insulating oil and PCB at this degree of vacuum is about 150 ° C. For this reason, when the temperature of the insulating oil becomes about 150 ° C., the temperature rise of the insulating oil becomes small due to the influence of the latent heat of evaporation even if the heating is continued. Therefore, by continuing heating while maintaining the degree of vacuum, all of the insulating oil and PCB were evaporated. After that, heating was continued, and when the temperature of the container began to rise and exceeded 200 ° C., the heating was stopped. Then, the insulating oil and P
The residual ratio of PCB in the decomposition product of CB was determined.

The above-described decomposition / recovery experiment of the PCB was carried out by changing the absorbed dose of the electron beam in the electron beam irradiation equipment 3, and the relationship between the absorbed dose rate of the electron beam and the PCB residual ratio was obtained. The result is shown in FIG. As shown in the figure, the PCB residual ratio decreased as the absorbed dose of the electron beam increased. In particular, when the absorbed dose rate was 16 or more, the PCB residual rate was 0, indicating that the PCB was completely decomposed.

[0039]

As is clear from the above description, according to the method for decomposing a hardly decomposable organic compound according to the first aspect,
By removing the hard-to-decompose organic compound from the electrical member by vacuum treatment and heating and irradiating the evaporated hard-to-decompose organic compound with an electron beam, the detoxification treatment of the electric member and the decomposition process of the hard-to-decompose organic compound are continuously performed Can be done Therefore, the removal of the hardly decomposable organic compound from the electric member and the decomposition thereof can be efficiently performed by a simple process.

Further, since all the reactions are completed in the decompressed sealing device, the safety of the working environment for the worker and the safety for the general public are sufficiently maintained. Since the present invention can be implemented as long as there is at least a vacuum heating facility and an electron beam irradiation facility, the apparatus can be downsized. For this reason,
The present apparatus can be a mobile plant, for example, loaded on a trailer to realize on-site processing for removing and decomposing a hardly decomposable organic compound at a transfer destination.

Further, according to the method for decomposing a hardly decomposable organic compound according to the second aspect, the electric member is heated at 100 mb.
Since the heat treatment is performed in an atmosphere of ar or less, the heat evaporation of the hardly decomposable organic compound can be best performed.

Further, according to the method for decomposing a hardly decomposable organic compound according to the third aspect, the heating of the electric member is 100 to 100.
Since the heat treatment is performed at 650 ° C., the evaporation of the hardly decomposable organic compound by heating can be performed most efficiently and efficiently.

According to the method for decomposing a hardly decomposable organic compound, the decomposition of the hardly decomposable organic compound by electron beam irradiation is performed in an atmosphere of 100 mbar or less. The decomposition of the decomposable organic compound can be performed best.

On the other hand, according to the method for decomposing a hardly decomposable organic compound according to the fifth aspect, even a member made of paper or wood from which it is relatively difficult to remove the hardly decomposable organic compound can be satisfactorily removed. At the same time, it becomes possible to efficiently and inexpensively decompose the removed hardly decomposable organic compound.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing processing equipment in one embodiment of the method for decomposing a hardly decomposable organic compound of the present invention.

FIG. 2 is a graph showing a relationship between an absorbed dose rate of an electron beam and a PCB residual rate.

[Explanation of symbols]

 1 electric member 2 vacuum heating equipment 3 electron beam irradiation equipment

 ────────────────────────────────────────────────── ─── Continued on front page F term (reference) 2E191 BA12 BA13 BD11 BD18 4D004 AA21 AB07 CA02 CA08 CA27 CA43 CB04 DA02 DA03 DA06 DA07 4G075 AA37 BA05 BB02 CA02 CA05 CA12 4H006 AA05 AC26

Claims (5)

[Claims] 1. An electric member containing a hardly decomposable organic compound is heated under reduced pressure to evaporate and remove the hardly decomposable organic compound. A method for decomposing a hardly decomposable organic compound, which is decomposed by irradiation. 2. The method according to claim 1, wherein the heating of the electric member is performed at 100 mbar.
The method for decomposing a hardly decomposable organic compound according to claim 1, which is performed in the following atmosphere. 3. The heating of the electric member is performed at 100 to 650.
The method for decomposing a hardly decomposable organic compound according to claim 1 or 2, wherein the method is carried out at a temperature of ° C. 4. The method according to claim 1, wherein the electron beam irradiation is performed in an atmosphere of 100 mbar or less.
The method for decomposing a hardly decomposable organic compound according to any one of the above. 5. The original electrical member is subjected to a treatment for removing the hardly decomposable organic compound, and then the electric member is disassembled, and a member made of metal or plastic is treated as a hardly decomposed material. The method is characterized by removing the hard-to-decompose organic compound from the remaining paper or wood member by the method for decomposing a hard-to-decompose organic compound according to any one of claims 1 to 4, and decomposing the remaining material. A method for decomposing hardly decomposable organic compounds.