JP2011218077A - Method for cleaning pcb in electric apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a simple and safe method for cleaning PCB in an electric apparatus, for simultaneously detoxifying and cleaning not only insulating oil but also an internal member present in the electric apparatus, while dissolving and detoxifying a small amount of PCB in the insulating oil containing PCB at normal temperature and normal pressure.SOLUTION: The method for cleaning PCB in a transformer 2 which stores the insulating oil 3 internally containing PCB includes: a process to successively extracting the insulating oil 3 from the transformer 2; a process to make the extracted insulating oil 3 be brought into contact with a ceramic treatment agent with alkali metal impregnated thereto and to dissolve the PCB thereby detoxifying the insulating oil; and a process to return the detoxified insulating oil 3 to the transformer 2. The processes are successively repeated at the normal temperature and normal pressure and the insulating oil 3 is circulated between the inner part of the transformer 2 and the ceramic treatment agent. Thus, the insulating oil 3 and the internal member 8 inside the transformer 2 are detoxified and cleaned.

Description

In the present invention, insulating oil in electrical equipment treated as specially controlled industrial waste, such as transformers using insulating oil containing PCB as insulating oil for electrical equipment such as transformers, and PCB in internal members at normal temperature and normal pressure. The present invention relates to a PCB purification method for electrical equipment that is detoxified and purified.
The detoxification in the present invention refers to a state in which the PCB concentration is reduced to a reference value or less based on a law on waste disposal and cleaning (hereinafter referred to as waste disposal law). The normal temperature refers to the range of 20 ° C. ± 15 ° C. (5-35 ° C.) defined in “JIS Z 8703”, and the normal pressure is the atmospheric pressure when the apparatus is stopped. Is the range of pressure required to circulate the insulating oil between the electrical equipment and the ceramic treating agent, and is usually about 1 atm.

Polychlorinated biphenyls (PCB) have been widely used in products such as insulating oils for electrical equipment such as transformers and capacitors because of their stable chemical properties and insulating properties. It was stopped and processed.
After that, the PCB treatment system was delayed and was kept for a while, but the Special Measures Law (hereinafter referred to as the PCB Special Measures Law) concerning the promotion of appropriate disposal of polychlorinated biphenyl waste in 2001 was enforced. Started PCB processing on a country basis.

However, it has been found that some electrical equipment manufactured after 1972 and not using PCB contains insulating oil contaminated with PCB of about several tens of ppm. There is a problem with the processing of electrical equipment in which insulating oil containing PCB is used.
There are a huge number of electrical equipment that uses this trace amount of PCB-containing insulating oil, with a nominal number of 1.2 million units, and there are many large and difficult-to-move devices. There is an urgent need to develop a method for detoxifying internal members of electrical equipment together with insulating oil.

  By the way, as a method for detoxifying PCB, as shown in Patent Document 1, a solid dechlorinated substance (mainly alkali metals) having a reactive group that reacts with the chlorine group of PCB is formed into a fixed layer filter. A method for providing a dechlorinated substance and bringing a liquid to be treated into contact with each other to render the PCB harmless is shown. However, this method is characterized by heating to a temperature lower than the melting point of the alkali metal, and there is a problem in safety due to the danger of ignition associated with the heating of the liquid to be treated (insulating oil).

JP-A-9-110735

  The technical problem of the present invention is to detoxify a small amount of PCB in insulating oil containing PCB at normal temperature and normal pressure, while simultaneously detoxifying not only the insulating oil but also internal members present in electrical equipment. It is to provide a simple and safe PCB purification method for electrical equipment that can be purified.

In order to solve the above-mentioned problems, the present inventors used a transformer that has been used as a representative of electrical equipment using a trace amount of PCB-containing insulating oil to insulate it with a device in which a column is filled with a ceramic treatment agent to which an alkali metal has been added. As a result of conducting many tests for purifying the transformer member while decomposing PCB in oil, the following knowledge was obtained.
-When an insulating oil mixed with a small amount of PCB was circulated at room temperature and normal pressure using an apparatus in which a ceramic treating agent impregnated with an alkali metal was packed in the column, the PCB concentration in the insulating oil decreased.
-The passage speed of the trace amount of PCB-containing insulating oil to the device is about 1-2 in terms of space velocity (SV), and the PCB can be efficiently decomposed.
・ The higher the temperature of the insulating oil to be passed, the better the PCB decomposition efficiency, but the risk of ignition, equipment costs, and handling of the equipment in the general environment (room temperature) is higher than the safety risk of heating. There are merits in terms of simplicity of power and simplicity of power supply.
・ In the electrical equipment members due to the PCB diffusion phenomenon due to the PCB concentration difference between the insulating oil and the internal parts of the electrical equipment, which are detoxified in the vicinity of the internal parts present in the electrical equipment by the ceramic processing agent with the alkali metal. PCB concentration is decreasing.
-The insulating oil that has been rendered harmless by passing through a device filled with a ceramic treatment agent impregnated with an alkali metal is temporarily stored in a tank, etc., and the stored insulating oil that has been rendered harmless is once again stored in a small amount of PCB-mixed electrical equipment. The PCB concentration in the internal member decreases by returning the detoxified insulating oil to the electrical equipment.

Based on the above knowledge, the present inventors safely and efficiently detoxify the insulating oil, and at the same time, circulate the detoxified insulating oil in the electric device to thereby reduce the PCB concentration in the internal member of the electric device. The inventors have come up with a method of reducing and detoxifying the internal member. The gist is as follows.
That is, the PCB purification method for an electrical device according to the present invention includes a step of sequentially extracting the insulating oil from the electrical device, and the extracted insulating oil in the PCB purification method for an electrical device in which the insulating oil containing PCB is contained. Is made harmless by bringing PCBs into contact with a ceramic treating agent impregnated with an alkali metal and decomposing PCB, and returning the harmless insulating oil to the electrical equipment. The insulating oil and the internal member in the electrical equipment are rendered harmless and purified by circulating the insulating oil between the electrical equipment and the ceramic treating agent successively and repeatedly at normal pressure.

  On the other hand, another PCB cleaning method for electrical equipment according to the present invention is a PCB purification method for electrical equipment in which insulating oil containing PCB is contained, and all the insulating oil is once extracted from the electrical equipment and temporarily stored in a tank. The insulating oil stored in the tank and the insulating oil stored in the tank are circulated between the tank and the ceramic treating agent impregnated with an alkali metal at normal temperature and normal pressure to bring the insulating oil into contact with the ceramic treating agent. In this way, the PCB in the insulating oil is sequentially decomposed, the step of detoxifying all of the insulating oil in the tank in advance, the step of returning the detoxified insulating oil into the electric device, and the return to the electric device A step of cleaning, detoxifying and purifying internal members in the electrical equipment by a liquid flow of insulating oil.

In the present invention, in the step of detoxifying the insulating oil by decomposing PCB through a ceramic treating agent impregnated with an alkali metal, the ceramic treating agent is packed in a column, and at normal temperature and normal pressure. By passing an insulating oil containing PCB through the column, the PCB in the insulating oil can be decomposed and rendered harmless.
Furthermore, in the present invention, in the step of returning the detoxified insulating oil to the electric device, a concentration gradient is generated between the detoxified insulating oil and the PCB concentration in the internal member in the electric device, By diffusing PCB in the internal member into the detoxified insulating oil, the internal member can be purified.

  Moreover, in this invention, the purification apparatus which performs each said process can be made movable, and the PCB of this electric equipment can be purified in the installation place of the said electric equipment.

  According to the present invention, after insulating oil containing PCB is extracted from electrical equipment and rendered harmless by the ceramic treating agent, the insulating oil is circulated while repeating the process of returning the harmless insulating oil to the electrical equipment again. As a result, the insulating oil containing PCB and the internal member containing PCB of electrical equipment are gradually detoxified and purified, so that the trace amount PCB in the insulating oil containing PCB is decomposed and made harmless, Not only the insulating oil but also the internal members present in the electrical equipment can be made harmless and purified at the same time. In addition, since this operation is performed at normal temperature and normal pressure, it is possible to safely perform PCB purification of the electrical equipment.

It is a schematic diagram of the purification apparatus used for 1st Embodiment of the PCB purification method which concerns on this invention. It is a schematic diagram of the purification apparatus used for 2nd Embodiment of the PCB purification method which concerns on this invention. It is a schematic diagram of the purification apparatus used for the effect experiment which concerns on the Example of the PCB purification method of this invention. It is a graph which shows the time-dependent change of PCB density | concentration of the insulating oil which concerns on the Example of the PCB purification method of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a purification device used in a first embodiment of a method for PCB purification of electrical equipment according to the present invention. In this embodiment, insulating oil containing PCB is used, and The case where a transformer having an internal member impregnated with PCB by the insulating oil is purified is shown.

  Specifically, the purification apparatus 1 includes a ceramic treating agent (not shown) to which an alkali metal that has decomposed PCB in the insulating oil 3 used in the transformer 2 and detoxifies the insulating oil 3 is attached. A vertical cylindrical column 4 filled with the ceramic treating agent; a primary pipe 5a for extracting the insulating oil 3 from the transformer 2 and flowing the insulating oil 3 into the column 4; 4 is provided with a secondary side pipe 5b for returning the insulating oil detoxified by the ceramic treating agent from 4 into the transformer 2. Further, the primary side pipe 5a is provided with a circulation pump 6 for circulating insulating oil between the transformer 2 and the column 4 through the primary side and secondary side pipes 5a and 5b. A filter 7 is provided in the secondary pipe 5b to remove the sodium chloride, sodium oxide, and biphenyls by filtering the insulating oil from which the PCB has been decomposed.

  The ceramic treating agent is obtained by coating the surface of a ceramic carrier with an alkali metal in a thin film shape, and is exchangeably packed in the column. The carrier is made of a porous material, thereby increasing the surface area of the alkali metal, increasing the contact efficiency between the alkali metal and the PCB, and improving the decomposition treatment capacity.

Here, the alkali metal used in the ceramic treating agent includes sodium and potassium, but it is desirable to use sodium from the viewpoint of economy.
Examples of the coating method include dipping coating and spraying, but it is desirable to coat the carrier as metal fine particles. Further, the ceramic treating agent is preferably attached with 1 to 50% by mass, preferably 5 to 20% by mass of alkali metal with respect to the mass of the carrier.

  In addition, the purification device 1 can be separated for each component, that is, the column 4 filled with a ceramic treating agent, and the primary and secondary pipes 5a and 5b, the circulation pump 6 and the filter 7. It has become. Then, by transporting each component member individually to the installation location of the transformer 2 to be purified and assembling at that site, the entire apparatus can be easily moved and work related to purification can be performed. ing.

When purifying the transformer 2 using the purification device 1 having the above configuration, first, the primary side pipe 5a is connected between the transformer 2 and the column 4 via the circulation pump 6, while the secondary side is connected. A preparatory process for connecting the pipe 5b between the column 4 and the transformer 2 through the filter 7 is performed.
After the preparation process is completed, as a first process, the circulating pump is driven 6 times, and the insulating oil 3 in the transformer 2 is allowed to flow into the column by a certain amount.
Next, as a second step, the insulating oil in the column 4 is brought into contact with the ceramic treating agent, and the PCB in the insulating oil 3 is decomposed and rendered harmless.
Thereafter, as a third step, the harmless insulating oil is filtered by the filter 7, and then the harmless insulating oil is returned into the transformer 2.
Then, the insulating oil is circulated between the transformer 2 and the column 4 while repeating the first to third steps.

At this time, in the first step, the insulating oil 3 in the transformer 2 is sequentially sent out to the column 4 sequentially by a fixed amount. At the same time, in the third step, the insulating oil rendered harmless through the second step. Are sequentially supplied into the transformer 2.
Therefore, in the transformer 2, the detoxified insulating oil is sequentially mixed into the remaining insulating oil 3 containing PCB, and when the first to third steps are repeated, The PCB concentration of the insulating oil in the transformer 2 gradually decreases, and eventually the entire insulating oil in the transformer 2 is rendered harmless.

On the other hand, the PCB contained in the internal member 8 disposed in the transformer 2 is reduced in the concentration of PCB in the insulating oil 3 in the transformer 2, thereby reducing the PCB concentration in the internal member 8. A difference (concentration gradient) is generated between the PCB concentration in the insulating oil. As a result, a PCB diffusion phenomenon occurs, and the PCB gradually elutes from the high concentration internal member 8 into the low concentration insulating oil 3.
Then, as the PCB concentration in the insulating oil decreases as the first to third steps are repeated, the PCB in the internal member 8 is also eluted into the insulating oil 3 in sequence, finally. Since all the PCB in the internal member 8 is removed, the detoxification and purification of the internal member 8 are completed.

As described above, after the insulating oil containing PCB is extracted from the electrical equipment and rendered harmless by the ceramic treatment agent, the insulating oil is circulated while repeating the process of returning the harmless insulating oil to the electrical equipment again. As a result, the insulating oil containing PCB and the internal member containing PCB of electrical equipment are gradually detoxified and purified, so that the insulation in the insulating oil containing PCB is decomposed and detoxified. Not only the oil but also the internal members present in the electrical equipment can be made harmless and purified at the same time.
In addition, since this operation is performed at normal temperature and normal pressure, it is possible to safely perform PCB purification of the electrical equipment.

  FIG. 2 shows a purification device used in the second embodiment of the PCB purification method for electrical equipment according to the present invention. In this embodiment, the same electric power as in the first embodiment is shown. The case where the transformer as equipment is purified is shown.

Specifically, the purification device 1 according to the second embodiment includes an insulating oil 3 before the circulation pump 6 in the primary pipe 5a in the purification device according to the first embodiment described above. A tank 9 for temporary storage is provided, and a second circulation pump 10 is provided in front of the tank 9 in the primary side pipe 5a separately from the circulation pump 6.
Further, in the secondary side pipe 5b, a first bypass pipe 11 that communicates between the secondary side pipe 5b and the circulation pump in the primary side pipe 5a and the column 4; A second bypass pipe 12 that is provided downstream of the first bypass pipe 11 and allows the insulating oil to flow into the tank 9 from the secondary pipe 5b, and is provided downstream of the second bypass pipe 12. A third bypass pipe 13 connected between the second circulation pump 10 and the tank 9 in the primary side pipe 5a is provided.

  In addition, about another structure, in order to show the same effect as the structure same as the purification apparatus which concerns on 1st Embodiment mentioned above, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

When purifying the transformer 2 using the purification device 1 having the above-described configuration, first, the second circulation pump 10 is driven, and the insulating oil 3 in the transformer 2 is passed through the primary side pipe 5a to the transformer 2. Once extracted from the tank, it is temporarily stored in the tank 9.
Next, the circulating pump 6 is driven, and the insulating oil stored in the tank 9 passes through the primary side pipe 5a, the column 4, the filter 7, the second pipe 5b, and the second bypass pipe 12 to the tank 9. And between the column 4 and the column 4 at normal temperature and normal pressure. Then, the insulating oil is brought into contact with the ceramic treating agent in the column 4 to sequentially decompose the PCB in the insulating oil. All the insulating oil in the tank 9 is once rendered harmless in advance and then returned to the tank 9.

Thereafter, the circulation pump 6 is driven, and the once detoxified insulating oil in the tank 9 is returned into the transformer 2 through the primary side pipe 5a, the first bypass pipe 11 and the secondary side pipe 5b.
Then, the second circulating pump 10 is driven and the insulating oil returned into the transformer 2 is again transferred from the transformer 2 through the primary side pipe 5a, the third bypass pipe 13, and the secondary side pipe 5b. The insulating oil is circulated through a path of returning to the inside 2 to generate a liquid flow, and the PCB adhering to the internal member 8 in the transformer 2 is washed away by the liquid flow of the insulating oil. At the same time, the PCB contained in the internal member 8 also has a low concentration of PCB from the internal member 8 on the high concentration side due to the PCB diffusion phenomenon due to the concentration gradient between the PCB concentration in the internal member 8 and the PCB concentration in the insulating oil. It elutes into the insulating oil on the side, and the PCB concentration in the internal member 8 is gradually lowered.

  Further, when the PCB of the internal member 8 is eluted and washed by the insulating oil circulation, the PCB concentration in the insulating oil increases. In this case, the insulating oil in the transformer 2 is removed from the primary side. Is extracted from the transformer 2 to the tank 9 through the pipe 5a, and the insulating oil is brought into contact with the ceramic treating agent. Then, after detoxifying the insulating oil again, the detoxified insulating oil is returned to the transformer 2 and the above-described process of cleaning the internal member 8 is repeated again. All the PCBs are removed, and the detoxification and purification of the internal member 8 are completed.

As described above, according to the second embodiment described above, basically the same effect as in the case of the first embodiment can be obtained, but in the case of this second embodiment, Before purifying the internal members of the transformer, the insulating oil is circulated between the tank 9 and the column 4, and all the insulating oil is once detoxified by the ceramic treatment agent in advance, and the once detoxified insulating oil and Since the internal flow of the internal member 8 in the transformer 2 can be efficiently cleaned and detoxified by the liquid flow, the insulating oil in the transformer 2 and the internal member 8 can be detoxified and purified quickly and stably. .
In particular, the insulating oil once detoxified and the concentration of PCB contained in the internal member 8 have a very large concentration gradient of PCB, so that the PCB in the internal member 8 easily diffuses into the insulating oil. There is an advantage that the detoxification and purification of the member 8 can be performed quickly.

  In the second embodiment, after the detoxified insulating oil is returned into the transformer 2, the insulating oil is supplied to the transformer 2, the primary side pipe 5a, the third bypass pipe 13, and the secondary side. The piping 5b is circulated through the path in the transformer 2 to generate a liquid flow in the insulating oil, and the PCB adhering to the internal member in the electrical equipment is washed away by the liquid flow of the insulating oil. Instead of a path through which the bypass pipe 13 is passed, a path including the column 4 and the filter 7 is used to feed the insulating oil into the transformer 2, the primary side pipe 5a, the column 4 and the filter 7, the secondary side pipe 5b, the transformer 2 You may make it circulate by the inside path | route. As a result, the insulating oil whose PCB concentration increases as the internal device 8 in the transformer is cleaned is brought into contact with the ceramic treating agent in the column 4 to reduce the PCB concentration in the insulating oil, while the transformer 2 and the column. Therefore, the insulating oil in the transformer 2 and the internal member 8 can be made harmless and purified more quickly.

The purification device 1 of the first and second embodiments is incorporated in a container (not shown) in a state of being placed on an oil pan (see FIG. 3 described later), and is movable as a whole. It is good. By adopting such an aspect, the container incorporating the purification device 1 is moved to the installation location of the transformer 2 containing the insulating oil containing PCB by a transportation means such as a railway, a ship, and a truck. It becomes possible to purify the transformer 2 in position.
In this case, it is preferable that a heavy metal adsorbing sheet (for example, a material containing zeolite) is mounted inside the container to take measures against contamination of PCB during movement. Further, the container may have a structure equipped with a ventilation device or a filter (for example, activated carbon).

In order to confirm the effect of the PCB cleaning method for an electrical device according to the present invention, an experiment was conducted on a transformer as an electrical device that was actually used.
In the experiment, purification work was performed using a transformer having a rated capacity of 10 kVA shown in the following table, and PCB concentrations at a plurality of specific locations in the transformer were measured.

The effect experiment was basically based on the first embodiment. Specifically, the transformer was purified by the purification device 1 as shown in FIG.
That is, in this purification apparatus 1, a cylindrical column 4 having an internal volume of about 2.5 liters is filled with 2 liters of a sodium metal adhering ceramic treatment agent 14, and the primary side pipe 5a includes a circulation pump 6 and the like. In addition, a flow meter 15 for measuring a flow rate is attached downstream of the circulation pump 6. A bypass pipe 16 communicating with the secondary pipe 5b is connected between the flow meter 15 and the circulation pump 6. Furthermore, thermometers 17 and 18 for measuring the temperature of the insulating oil are attached to the upstream side of the filter 7 in the secondary side pipe 5b and the transformer 2, respectively.
On the other hand, the transformer 2 to be purified includes an iron core 8a, a coil portion 8b (including primary conductor, secondary conductor, insulating paper, wood) wound around the iron core 8a, and an iron core 8a in the case 2a. A base member to be placed in 2a and an insulator 8c to which a conducting wire is connected are arranged as an internal member 8, and further filled with insulating oil 3.
The purification of the transformer 2 by the purification device 1 is performed on the oil pan 19.

The main conditions for the purification of the transformer are as shown in Table 2.
In the effect experiment of the present invention, the insulating oil in the transformer is appropriately sampled and the PCB concentration in the insulating oil is measured. The PCB concentration of the insulating oil in the transformer is a target value of 0.3 ppm (0.3 mg / kg). ) Purification was performed until Thereafter, the internal member 8 was taken out from the transformer 2 and left for two days and nights to drain the internal member 8. Subsequently, the coil portion 8b and the iron core 8a were disassembled, and samples for analysis were collected from specific plural places. Table 3 shows the details of the sampling points.

  Further, for each collected sample, the PCB concentration was measured by an assay method based on the waste treatment method. Evaluation method for each sample and judgment standard of PCB concentration based on waste disposal method ("PCB disposal technology guidebook (revised edition), pages 412 to 415, edit: Industrial Waste Disposal Business Promotion Foundation, Publishing: Co., Ltd. Table 4 shows “Gyosei, August 2005”.

As a result of carrying out the purification method according to the present invention, as shown in FIG. 4, the PCB concentration of the insulating oil decreased to the graduation judgment standard (0.5 ppm) indicated in the waste treatment method on the 20th day from the start of the treatment. On the 27th day, the target value of this test, 0.3 ppm, was achieved.
On the other hand, Table 5 shows the measurement results of the PCB concentration of the sample collected from the internal member of the transformer.

It was confirmed that all the PCB concentrations of the samples collected from the internal members satisfied the graduation judgment standards stipulated in the Waste Management Law.
Therefore, it was proved that the insulating oil and the internal member of the transformer can be rendered harmless and purified by carrying out the purification method of the present invention.

2: Transformer 3: Insulating oil 4: Column 8: Internal member 9: Tank 14: Ceramic treatment agent

Claims (5)

  In a method for purifying PCB in an electrical device in which insulating oil containing PCB is contained, a step of sequentially extracting the insulating oil from the electrical device, and the extracted insulating oil is brought into contact with a ceramic treatment agent to which an alkali metal is attached. The step of detoxifying the PCB by decomposing it and the step of returning the detoxified insulating oil to the electrical equipment are repeated in the electrical equipment by sequentially repeating these steps at normal temperature and normal pressure. A method for PCB purification of electrical equipment, wherein the insulating oil and internal members in the electrical equipment are rendered harmless and purified by circulating between the ceramic treatment agent and the ceramic treatment agent.   In the method of purifying PCB in an electrical device in which insulating oil containing PCB is contained, a step of temporarily extracting all the insulating oil from the electrical device and temporarily storing it in a tank, and the insulating oil stored in the tank, Circulation between the tank and the ceramic treatment agent impregnated with an alkali metal is performed at normal temperature and normal pressure, and the insulating oil is brought into contact with the ceramic treatment agent to sequentially decompose the PCB in the insulation oil. The step of detoxifying all the insulating oil in advance once, the step of returning the detoxified insulating oil into the electric device, and cleaning the internal members in the electric device by the liquid flow of the insulating oil returned into the electric device, A method for PCB purification of electrical equipment, comprising the step of detoxifying and purifying.   In the step of detoxifying the insulating oil by decomposing PCB through a ceramic treating agent impregnated with an alkali metal, the ceramic treating agent is filled in a column, and the PCB is placed on the column at room temperature and normal pressure. 3. The PCB purification method for an electrical device according to claim 1, wherein the PCB in the insulating oil is decomposed and rendered harmless by passing the insulating oil contained therein.   In the step of returning the detoxified insulating oil to the electrical device, a concentration gradient is generated between the detoxified insulating oil and the PCB concentration in the internal member in the electrical device, and the PCB in the internal member is 4. The method of purifying a PCB of an electric device according to claim 1, wherein the inner member is purified by diffusing into the detoxified insulating oil. 5. The electrical equipment PCB according to claim 1, wherein a purification device that performs each of the steps is movable, and the electrical equipment PCB is purified at an installation location of the electrical equipment. 6. Purification method.

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