JP2016168532A - Cleaning method of electrical equipment contaminated with pcb - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of removing PCB from an inner member by a simple method and in a short time without dismantling even in electrical equipment such as a transformer core having the inner member not being immersed with a cleaning oil inside as it is.SOLUTION: A cleaning method of electrical equipment contaminated with PCB and stored inside with a PCB-containing insulation oil includes: an oil withdrawing step of withdrawing the insulation oil from the electrical equipment; a varnish removal step where a varnish remover is charged into the electrical equipment withdrawn with the insulation oil and a waste liquid containing the varnish remover is withdrawn after holding in a prescribed time; and a PCB cleaning step where a cleaning oil is charged into the electrical equipment after finishing the varnish removal step and the inside of the electrical equipment is cleaned.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for cleaning electrical equipment contaminated with polychlorinated biphenyl (PCB), particularly waste electrical equipment.

  PCB has been widely used as an insulating oil for various electric devices such as transformers and capacitors because it is chemically very stable and excellent in electrical insulation. However, since the Kanemi oil symptom incident, the human body and environmental pollution due to its toxicity have caused problems and production has already been discontinued.

  However, it has been found that the insulation oil of electrical equipment that is not using this PCB contains several tens of ppm of PCB, and the electrical equipment is said to be 1.6 million according to the Ministry of the Environment. Processing is a problem.

  As a technology to deal with this, a cleaning method has been developed in which a PCB-contaminated electrical device and a ceramic-filled column impregnated with metallic sodium are connected by piping, and PCB-contaminated oil in the electrical device is circulated with a circulation pump to decompose the PCB. (Patent Document 1). PCB contained in the contaminated oil can be rendered harmless by reacting with metallic sodium. In this method, since the PCB of the insulating oil is decomposed during the circulation, the concentration of the PCB contained in the internal member of the electrical equipment can be reduced by diffusion.

  However, even with such a method, PCBs may not be removed when a thin steel sheet of about 0.2 to 0.3 mm, such as a transformer core, is laminated in multiple layers. This is because the laminated steel plates are often solidified with an adhesive resin such as an electrical insulating varnish. Insulating oil penetrates between the laminated steel plates, and they adhere to the steel plates for a long time. It is because it ends up. For this reason, after performing the above-described circulation cleaning, it is necessary to disassemble the electrical equipment, take out the iron core, further separate the iron core into individual steel plates, and then perform further cleaning (Patent Document 2).

JP 2011-218077 A JP 2012-232237 A

  The problem of the present invention is that even an electric device having an internal member that does not allow cleaning oil to enter inside as it is, such as a transformer core, can be easily removed from the internal member in a short time without being disassembled. The goal is to develop a method that can remove PCBs.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have successfully removed varnish that can be removed by dissolving or decomposing the adhesive resin such as an electrical insulating varnish that has solidified the periphery of the iron core of the transformer core. If you find the agent, extract the insulating oil from the electrical equipment, dissolve or decompose the varnish with this varnish remover, and then wash it with the cleaning oil, the electrical equipment can be disassembled and the PCB contained in the internal member The present invention has been completed by finding that it can be easily removed by washing.

  That is, the present invention relates to a method for purifying an electrical device in which an insulating oil containing PCB is housed, and an oil extracting step for extracting the insulating oil from the electric device, and a varnish for the electric device from which the insulating oil has been extracted. A PCB for removing the waste liquid containing the varnish removing agent after the removing agent is added and holding for a predetermined time, and a PCB for washing the interior of the electrical equipment by supplying cleaning oil to the electrical equipment after the varnish removing process is completed. An object of the present invention is to provide a method for purifying an electrical device contaminated with PCB, characterized by having a cleaning process.

  According to the present invention, the PCB can be efficiently removed from the electrical equipment in which the insulating oil containing the PCB is accommodated without being disassembled.

It is process drawing which shows the outline of one embodiment of this invention. It is process drawing which shows the outline of another embodiment of this invention. It is a figure which shows the outline of the varnish removal process in another embodiment of this invention.

  The electrical equipment to which the present invention is applied is one in which insulating oil is accommodated inside and varnish is applied to the surface of the internal member. A typical one is a transformer. The insulating oil is mineral oil, silicone oil or the like. The concentration of PCB contained in the insulating oil is usually about 0.5 to 5000 mg / kg (ppm), particularly about 0.5 to 100 mg / kg (ppm). The varnish is mainly composed of thermosetting resin such as alkyd resin and unsaturated polyester resin, and the coating thickness is about 2 to 5 μm, usually about 3 to 4 μm.

  The method for purifying an electrical device according to the present invention is to clean and remove PCB contained in insulating oil in the electrical device with cleaning oil, and the PCB concentration in the cleaning oil is less than 0.5 mg / kg. Is used as a criterion for completion of cleaning.

Oil extraction step This is a step of extracting the insulating oil containing PCB from the electrical equipment. Usually, the oil may be sucked using a pump, and then washed with cleaning oil as necessary. It is also known to efficiently remove oil using a solvent (Japanese Patent Laid-Open No. 2013-198871), and this can also be used. The extracted insulating oil can be decomposed and detoxified by incineration.

Varnish removal process The varnish removal agent is put into the electrical equipment from which the insulating oil has been extracted. The varnish removing agent includes an oxidizing agent such as hydrogen peroxide, an agent containing an organic bromine compound such as normal propyl bromide, an agent containing an organic compound having a 5-membered lactam structure such as N-methyl-2-pyrrolidone, 1- A drug containing an alcohol having an ether bond such as (2-methoxy-2-methylethoxy) -2-propanol can be used. These can be used in a liquid or vapor state. In the case of a liquid, the varnish removing agent can be put into an electric device while the varnish removing agent remains in a liquid state, or can be added after being mixed or dissolved with other oils or chemicals. As the solvent, hydrocarbon oils such as kerosene and heavy oil, ketones such as acetone, alcohols such as methanol and ethylene glycol, etc. can be used, and the concentration is not particularly limited, but may be 5 to 100% by mass. I can do it. On the other hand, even if the varnish removing agent is supplied by steam, it can be condensed on the surface of the varnish to fulfill the function of the varnish removing agent. The amount of varnish remover used is maintained for a predetermined period of time, so that the degree of varnish removal can penetrate, for example, between the steel sheets of the iron core in the subsequent PCB cleaning treatment process. The amount of residual varnish is 20% or less (removal rate is 80% or more), or the amount of PCB remaining in the cleaning oil is 0.5 ppm or less after cleaning in the subsequent PCB cleaning process. is there.

  The removal of the varnish can be performed by introducing a varnish remover into the electric device and bringing the varnish remover into contact with the varnish. At that time, it can be heated to accelerate varnish removal. The temperature for heating ranges from room temperature to the flash point of the varnish remover or solvent, preferably about 40 ° C to 60 ° C. In addition, ultrasonic irradiation can be performed to promote varnish removal. The holding for a predetermined time in the varnish removing step is a time for which the above-mentioned degree of varnish removal is achieved by the above-mentioned holding for a predetermined time, and is practically set to about 0.25 to 24 hr, preferably 0.5 to 6 hr. It is desirable to do.

  The varnish removing agent is preferably used repeatedly for effective use, and in that case, the varnish removing agent is preferably separated and reused by distillation or the like. When the varnish remover is dissolved in a solvent, it is used repeatedly as it is. In addition, a part of it can be withdrawn as a blow liquid through circulation.

  After the varnish removing step is completed, the varnish removing agent may be extracted from the electric equipment and incinerated, for example, or the PCB content of the varnish removing agent is 0.5 mg or less, and the cleaning oil is used in the next PCB washing treatment step. Can be used as it is as a cleaning oil without being extracted.

PCB cleaning treatment step This step is a step of removing the PCB by washing the interior of the electrical equipment from which the varnish has been removed in the varnish removing step with washing oil.

  As the cleaning oil, those having high solubility and miscibility with insulating oil such as mineral oil are preferable, and hydrocarbons such as kerosene and insulating oil can be used. Since the PCB is removed, a cleaning oil having a PCB content of 0.5 mg / kg or less, preferably 0.1 mg / kg or less is used.

  The cleaning method can be performed by circulating cleaning oil in the electrical equipment. Circulation means moving from the reservoir to another container and then returning to the original reservoir. Circulation can be performed using a circulation pump or the like. These can be circulated by evaporating the cleaning oil in a liquid form. When it is vaporized and circulated, it condenses and liquefies when it comes into contact with the iron core. The cleaning oil can be replaced with new cleaning oil on the way. The number of exchanges may be about 1 to 3 times.

  Cleaning is performed until the PCB concentration of the internal member such as cleaning oil or iron core becomes 0.5 mg / kg or less. The temperature may be room temperature, but can be heated if necessary. The heating temperature is below the flash point of the cleaning oil, and preferably about 40 to 70 ° C. The cleaning time is determined from a practical point of view, for example, about 6 to 48 hours. Washing ends when the PCB concentration of the washed oil after washing becomes 0.5 mg / kg or less. Since the cleaning oil at the end usually has a PCB concentration of 0.5 mg / kg or less, it can be reused as cleaning oil. If the reuse is continued as it is, the PCB concentration will exceed 0.5 mg / kg. Therefore, it is recommended to continue washing while extracting a part or all of the PCB and adding new washing oil. In particular, if a PCB decomposition process is added, the reuse rate can be increased. Cleaning oil that is not reused may be incinerated at a PCB waste oil incineration facility.

PCB Decomposition Processing Step Only the cleaning with the cleaning oil may be performed in the PCB cleaning processing step, but the PCB can be more efficiently removed by adding the PCB decomposition processing step. In this step, the PCB contained in the cleaning oil is decomposed by the PCB decomposing agent. As the PCB decomposing agent, an alkali metal, particularly metal sodium is used. In the present invention, any known PCB decomposing agent can be used. For example, the metal sodium-added ceramic described in Patent Document 1 can be preferably used. Specifically, it is preferable that a circulation line is provided by connecting a vessel filled with a PCB decomposing agent containing metal sodium as a main component and an electrical device, and circulating for a predetermined time. This metallic sodium-impregnated ceramic is obtained by coating metallic sodium on the surface of a porous ceramic by a dipping method or a spray method, and the amount of metallic sodium is about 5 to 20% by mass of the ceramic. The reaction temperature may be room temperature, but the reaction can be promoted by heating. As heating temperature, it is below the flash point of cleaning oil, and about 40-70 degreeC is suitable. The reaction time may be until the PCB concentration of the cleaning oil or the internal member becomes 0.5 mg / kg or less, and is usually terminated when the PCB concentration of the cleaning oil becomes 0.5 mg / kg or less. In this way, by performing the PCB decomposition process after the PCB cleaning, the PCB concentration in the cleaning oil can always be maintained at a low level, so that the cleaning can be performed efficiently and the cleaning oil can be reused multiple times. Become.

One embodiment of the present invention is shown in FIG. As shown in the figure, this insulating oil, which is a contaminated oil, is first extracted from a transformer in which a varnish is applied to an iron core and an insulating oil containing PCB is accommodated therein. Next, the varnish removing agent is put into the transformer from the storage tank, and after holding for a predetermined time, the remaining varnish removing agent and the waste liquid containing dissolved or decomposed varnish are extracted. After extracting this waste liquid, the cleaning oil that has been heated in advance from the cleaning oil supply tank is put into the transformer. Part of the supplied cleaning oil is circulated for a predetermined time between the transformer and a container filled with a PCB decomposing agent mainly composed of metallic sodium. The PCB is decomposed by such an operation, and after the PCB concentration becomes 0.5 mg / kg or less, or at that time, the cleaning oil is extracted from the transformer and stored in the cleaning oil receiving tank. Transformers that have finished draining the cleaning oil are reused as resources after dismantling. On the other hand, a part of the cleaning oil stored in the cleaning oil receiving tank is taken out from the receiving tank, returned to the cleaning oil supply tank, and reused for cleaning another transformer. Further, another part of the cleaning oil stored in the cleaning oil receiving tank is extracted as waste cleaning oil.
The above-mentioned contaminated oil, waste liquid containing dissolved or decomposed varnish and waste cleaning oil are incinerated.

  Another embodiment of the present invention is shown in FIG. This embodiment is a case where the PCB concentration in the insulating oil is as low as about 10 mg / kg or less, and the varnish removing agent is heated when the varnish removing agent is added to dissolve or decompose the varnish, Except for the point that the waste liquid after completion of the varnish removal process is used as a cleaning oil used in a cleaning process step, which is the next processing step, this is the same PCB cleaning method for an electrical device as in the embodiment of FIG.

Another embodiment of the varnish removal step is shown in FIG. In this embodiment, the varnish remover is mixed with other chemicals such as kerosene, and this is put into the transformer, and the varnish remover is heated to below the flash point and irradiated with ultrasonic waves in the transformer. After the varnish removal process is completed, the waste liquid containing the varnish dissolved or decomposed product is extracted from the transformer and placed in a receiving tank, and a part of the waste liquid is removed as it is or by distillation regeneration. 1 is the same as the embodiment shown in FIG. 1, except that it is returned to the storage tank and partly extracted as a dissolved waste liquid.

  As an example of the present invention, a varnish removal test was performed.

  As the test piece, an alkyd resin-based electrical insulating varnish with a thickness of 3.5 μm was applied to both sides of a 20 mm × 30 mm × 1 mm thick steel plate.

  This test piece was put into various varnish removers, and the removability by dissolution or decomposition of the varnish was examined under various conditions.

First, as a varnish removing agent, when immersed in an organic bromine-based chemical (“esolv 21HE”, Kaneka Chemical Product) at room temperature (about 20 ° C.) for 24 hours, all the varnish was removed. _Also, after immersion for one hour at 40 ° C. in H ₂ O ₂ (35 wt% aqueous solution), and further, was immersed normal temperature (20 ° C.) in 23 hours, the varnish had been removed.

次に、蒸留回収したワニス除去剤による常温でのワニス除去試験、加温でのワニス除去試験および加温超音波によるワニス除去試験を行った結果を表２示す。
蒸留回収したＮ−メチル−２−ピロリドンを含む薬剤は、常温でのワニス除去試験においても良好なワニス除去性を示した。
また、Ｈ_２Ｏ_２を使用した加温でのワニス除去試験では、温度を５０℃に上げると良好なワニス除去性が得られることがわかった。
さらに、アルコール系薬剤を使用した加温超音波によるワニス除去試験では、温度を３０℃に上げると良好なワニス除去性が得られることがわかった。

Next, Table 1 shows the results of a varnish removal test at normal temperature, a varnish removal test by repeated use at normal temperature, and a varnish removal test by mixing with kerosene at normal temperature. In addition, normal temperature is 15-20 degreeC. In addition to the aforementioned drugs, drugs containing N-methyl-2-pyrrolidone (“Resin Cleaner US-100”, manufactured by Nissin Chemical Laboratory), alcohol-based drugs (“HA-IS16”, manufactured by Tosoh Corporation), and ether-based drugs A solvent (“AE-100”, manufactured by Nissin Chemical Laboratory) was used as a varnish remover. In the varnish removal test soaked at room temperature for 1 hour, the varnish can be removed with a chemical other than the ether solvent. It was. Moreover, in the varnish removal test by repeated use at normal temperature using these two chemicals, both showed good varnish removability even when used repeatedly 8 times. Furthermore, in the varnish removal test by mixing with kerosene at room temperature using a drug containing N-methyl-2-pyrrolidone, good varnish removability was shown at any mixing ratio.

Next, Table 2 shows the results of a varnish removal test at normal temperature, a varnish removal test with heating, and a varnish removal test with heating ultrasonic waves using the distilled and recovered varnish removing agent.
The drug containing N-methyl-2-pyrrolidone recovered by distillation showed good varnish removability in a varnish removal test at room temperature.
Moreover, in the varnish removal test by heating using H ₂ O ₂ , it was found that when the temperature was raised to 50 ° C., good varnish removability was obtained.
Furthermore, in a varnish removal test using a heated ultrasonic wave using an alcohol-based chemical, it was found that good varnish removability can be obtained when the temperature is raised to 30 ° C.

Next, an iron core is extracted from a transformer that does not contain PCB, and an alkyd resin-based electrical insulating varnish is applied by dip coating, and a varnish removal experiment using a drug containing N-methyl-2-pyrrolidone as a varnish removing agent is conducted. Carried out. The results are shown in Table 3, and the varnish was completely removed by immersing in a drug containing N-methyl-2-pyrrolidone at room temperature for 2 hours.

  According to the present invention, PCB can be efficiently removed from an electric device having an insulating oil containing PCB therein, and therefore the method of the present invention can be widely used for the treatment.

Claims (4)

  A method for purifying an electrical device in which insulating oil containing PCB is housed, wherein an oil removing step for extracting the insulating oil from the electric device, and a varnish removing agent is added to the electric device from which the insulating oil has been extracted, After holding for a predetermined time, a varnish removing step for extracting the waste liquid containing the varnish removing agent, and a PCB cleaning treatment step for cleaning the inside of the electric device by supplying cleaning oil to the electric device after the varnish removing step is completed. A method for purifying electrical equipment contaminated with PCB. 2. The method for purifying an electric device contaminated with PCB according to claim 1, wherein a waste liquid containing a varnish removing agent produced in the varnish removing step is used as a washing oil in the PCB washing treatment step.   The PCB cleaning treatment step includes a PCB decomposition processing step in which the cleaning oil is circulated for a predetermined time between the electric device and a container filled with a PCB decomposition agent mainly composed of metallic sodium. Item 3. A method for purifying electrical equipment contaminated with PCB according to Item 1 or 2.   The varnish removing agent is an agent containing an oxidizing agent such as hydrogen peroxide, an organic bromine compound such as normal propyl bromide, or an organic compound having a 5-membered lactam structure such as N-methyl-2-pyrrolidone. The PCB according to any one of claims 1 to 3, which is a drug containing an alcohol having an ether bond such as 1- (2-methoxy-2-methylethoxy) -2-propanol. To clean electrical equipment polluted with water.

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