JPH04202500A - Method for purifying electrical insulating oil - Google Patents

Abstract

PURPOSE:To highly and effectively remove and purify impurities contained in an electrical insulating oil which contains an organochlorine compound by dehalogenating the oil in a hydrogen gas atmosphere in the presence of a specified metallic catalyst under heating condition. CONSTITUTION:An electrical insulating oil containing an organohalogen compound such as polychlorinated biphenyl as impurities is put in a hydrogen gas atmosphere, and purified by dehalogenating in the presence of a base metal catalyst mainly comprising a zeolite-nickel catalyst or nickel-molybdenum or nickel-platinum under heating condition. The impurities are effectively removed, since this process is a vapor-liquid reaction in a hydrogen gas atmosphere and its operation is easy, and organic oxides are reduced. The obtained insulating oil can be reused as a regenerated insulating oil, since its color tone is turned pale and its insulating properties are improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for refining electrical insulating oil used in insulating oil-filled capacitors, oil-filled cables, oil-filled transformers, oil-filled circuit breakers, etc. The present invention relates to a purification method for removing impurities from electrical insulating oil containing organic chlorine compounds and peroxides as impurities.

[Conventional technology]

Electrical insulating oil is an MA-related oil whose main component is, for example, mineral oil, and as specified in JIS C2320, it is free from impurities that are undesirable as an insulating oil, especially water, water, etc.
Upper limits are set for the inclusion of suspended matter and other harmful substances. However, during long-term use of electrical insulating oil, peroxides and other impurities that inhibit insulation are formed due to chemical changes and the like. Furthermore, in recent years, it has been reported that trace amounts of organic chlorine compounds are mixed into electrical insulating oils used in capacitors, transformers, and the like. Gas chromatography electron capture detector (hereinafter sometimes abbreviated as gas chromatography ECD) revealed that these organic chlorine compounds were mainly polychlorinated biphenyls (PCB), and quantitative analysis revealed that these organic chlorine compounds It has been confirmed that electrical insulating oil contains several ppm to several hundred ppm.

PCBs are carcinogenic toxic chemicals, and as regulated by the Pollution Control Law, M! , it is not preferable for it to be contained in the edges.

Examples of techniques for refining contaminated electrical insulating oil include alkali metal treatment and solvent extraction.

There are adsorption methods, combustion methods, etc., but both have enormous processing costs, and the combustion method in particular requires a high combustion temperature.
If the temperature is low, toxic oxidants are likely to be generated and cause secondary pollution, so it cannot be practically used. Furthermore, these methods are not suitable from the viewpoint of resource reuse because the insulating oil after treatment cannot be reused, and are extremely disadvantageous from an industrial perspective. If we focus on PCBs, their dechlorination treatment is described in, for example, JP-A-49-54043 and JP-B-Sho.
6-42567, but none of them can be used industrially, and even if carried out in a laboratory, it is difficult to reduce the content of organic chlorides to below the detection limit of gas chromatography ECD. It is difficult to reduce it. Therefore, in practice, it has been necessary to use expensive high-temperature combustion equipment for treatment.

[Problem to be solved by the invention]

In view of the actual situation of the above-mentioned @ki insulation song, the present inventors
In particular, attention was focused on a chemical purification method for contaminated electrical insulating oil containing PCB and other impurities that does not have the above-mentioned drawbacks.

That is, an object of the present invention is to provide an industrially applicable refining method for contaminated electrical insulation oil containing PCBs. Another issue is PCBs in contaminated insulating oil.
For example, the detection limit value of gas chromatography ECD is 0, 5
It is an object of the present invention to provide a reusable purified electrical insulating oil whose concentration has been reduced to ppm or less.

[Means to solve the problem]

The present inventors conducted extensive research to solve the above problems, and as a result, discovered an industrially desirable method for refining and regenerating contaminated electrical insulating oil.

That is, 1. the present invention provides electrical insulating oil containing organic chlorine compounds as impurities in a hydrogen gas atmosphere in the presence of a zeolite/nickel catalyst or a base metal catalyst having a skeleton of nickel/molybdenum or nickel/platinum and under heating conditions. Below, a method for refining electrical insulating oil, which is characterized by dechlorination, is provided.

The electrical insulation oil targeted in the method of the present invention is PCB
Contains organic chlorine compounds including.

Contaminated electrical insulating oils containing peroxides and other undesirable impurities in insulating oils that may have been formed during use, and which are the most contaminated Ml! Includes oil.

Further, the catalyst used in the dechlorination reduction reaction of the present invention is a zeolite-nickel catalyst and a base metal catalyst having a skeleton of nickel-molybdenum or nickel-platinum.

Such nickel-based catalysts, such as zeolite nickel catalysts, can be activated by applying nickel ions to the surface of a ceolite carrier and subjecting the nickel ions to a heating reduction treatment at a temperature of around 400"C in a hydrogen stream. In addition, base metal catalysts with nickel/molybdenum or nickel/platinum skeletons are produced by melting and mixing nickel metal, molybdenum metal, platinum, aluminum, etc. at temperatures of 1,400°C or higher to form intermetallic compounds. , cooled, ground, and then prepared as an activated catalyst by eluting the aluminum with an aqueous solution of acid, alkali, or alkali salt.These catalysts are usually used alone, but can also be used in combination. .

In the method of the present invention, the catalyst prepared as described above is added to purified contaminated insulating oil, and the dechlorination reaction is carried out under heating temperature conditions where the hydrogenation reaction proceeds in a hydrogen gas atmosphere while stirring. . The amount of catalyst added to electrical insulating oil varies depending on the amount and type of impurities contained, but is usually about 0.5 to 10% by weight, preferably 1 to 8% by weight, based on the insulating oil. be.

The insulating oil mixed with the catalyst is placed in a reaction vessel, for example, an autoclave, the head space is replaced with hydrogen gas, and the oil is heated under stirring conditions. The heating temperature is selected empirically so that the dechlorination reduction reaction proceeds at an appropriate rate.

The preferred temperature is 150-250°C.

The dechlorination reaction rate of the organic chlorine compound varies depending on the type, amount, and temperature of the catalyst, and dechlorination is usually substantially completed in about 2 to 8 hours. When the reaction is completed, first, the catalyst is filtered from the insulating oil, then a small amount of water is added and shaken well to transfer the water-soluble components, and the layers are separated to remove the aqueous layer. The treatment removes dissolved water and other vaporized components.

The electrical insulating oil refined in this manner satisfies various physical property conditions stipulated by JIS and can be reused as recycled insulating oil without any problems.

[Effect]

Since the dechlorination reduction reaction of the present invention is a gas-liquid reaction in a hydrogen gas atmosphere, it is easy to operate, organic oxides are also reduced, and impurities are effectively removed. In addition, the color tone of the insulating oil has been lightened, and M! It can be reused as edge oil.

〔Example〕

Hereinafter, the method of the present invention will be explained in more detail using specific examples.

Zeolite nickel catalyst: Put 1.5Q of a 20% aqueous solution of sodium aluminate and an aqueous solution of 843g of caustic soda in 28kg of pure water into a stainless steel reaction pot with a 50Q steam jacket, and stir well with a stirrer. , No. 3 sodium silicate 6.
07 kg was added. Next, steam was passed through the jacket of the reaction vessel, and the reaction vessel was heated to 100° C. and reacted for 14 hours while maintaining that temperature and stirring. After the reaction, 50
The mixture was cooled to .degree. C., and the white crystals formed were filtered off using a Buchner funnel.The crystals were further washed with 120Q pure water in the vicinity of PHIO, and then dried to obtain 657 g of white powder.

This white powder was confirmed to be P-type zeolite crystals by X-ray diffraction and elemental analysis. Furthermore, it was confirmed by electron micrographs that the particles were spherical particles with a particle size of 1 to 3 μm.

160 g of the obtained zeolite was dispersed in 470 cc of water, and 450 g of 0.3N ammonium chloride aqueous solution was added to this.
cc was added and stirred at a temperature of 80-100°C for 3 hours to ion-exchange sodium in the zeolite with ammonium. The ion exchange rate was 85%. After ion exchange, filter with a Buchner funnel, wash with purified water,
After dispersing in 0 cc of pure water, add 400 cc of a mixed aqueous solution of 0.1 N nickel chloride and nickel nitrate 1:1, and stir at a temperature of around 80°C for 4 hours to dissolve ammonium ions and nickel ions in the zeolite. After replacing and thoroughly washing with pure water IQ, filter.

Dry. The resulting powder was further calcined at a temperature of 400'C for 3 hours.

50g of the obtained calcined powder was placed in a stainless steel (SUS 316) hydrogen reduction device with a diameter of 50Il1m, and the temperature was reduced to 51g per minute.
Reduction treatment was performed under heating temperature conditions of 400° C. in a hydrogen stream with a flow rate of 2. Completion of reduction was determined by the production of water and the dew point of hydrogen in the hydrogen stream. After completion of the reduction, the reactor was cooled to room temperature, hydrogen gas was replaced with nitrogen gas, and nitrogen gas mixed with 1100 pp of air was flowed at a rate of IQ per minute for 6 hours, and the reactor was taken out into the atmosphere. The powder thus obtained was black in color, and only the nickel peak was confirmed as a result of X-ray diffraction.
It was confirmed that it was activated as a catalyst. Also,
This activated zeolite-supported nickel catalyst has a specific surface area of 56 m' measured by the BET method, and elemental analysis by atomic absorption spectrometry reveals that it contains 15% by weight of nickel and 6% sodium.
% by weight.

Nickel-molybdenum catalyst: 2.5 kg of metal disokel + 350 g of metal molybdenum and 2.15 kg of aluminum in a graphite crucible for about 1600 g
A ternary alloy intermetallic compound was prepared by heating and melting at ℃.

The heated molten alloy was poured into an iron mold, cooled, pulverized with an atomizer, and sieved through a 200-mesh sieve. 50g of alloy fine powder that has passed through 200 meshes was put into a stainless steel reaction pot together with pure water IQ, heated to 40℃ while stirring and dispersing, and Bayerite 10 was added to this.
0 g was gradually added and stirred for about 30 minutes.

This was then added with a 20% aqueous solution of sodium hydroxide,
Add 3cc of aluminum, heat to a temperature of 40 to 50°C, keep stirring at that temperature for about 2 hours, and completely change the aluminum in the alloy powder to aluminum hydroxide, forming a nickel-molybdenum black powder catalyst. was prepared.

Nickel/platinum based catalyst: 2.5 kg of metallic nickel + 200 g of platinum and 2.3 kg of aluminum were treated in the same manner as the nickel/molybdenum based catalyst to prepare a nickel/platinum based black powder catalyst.

Example 1 A contaminated brown JIS Class 1 No. 2 electrical insulating oil containing 20 ppm of organic chlorine compounds mainly composed of PCBs measured by gas chromatography ECD was treated as follows using the above zeolite/nickel catalyst. Dechlorination and purification treatment was performed.

The above-mentioned contamination occurred in a stainless steel autoclave with a capacity of 500m Q! After adding 250g of edge and 2.5g (equivalent to 5% by weight of insulating oil) of catalyst] and completely replacing the upper space with hydrogen gas, the hydrogen gas pressure was set to 80kg/ffl.
The reaction was carried out for 5 hours while keeping the internal temperature at 200°C. After the reaction was completed, the contents were removed from the autoclave, the catalyst was filtered out, 50 cc of pure water was added to the oil, and the mixture was stirred well.
After oil and water separation and deaeration treatment, pale yellow refined oil 240
I got g.

When the amount of organic chlorine substances in purified insulating oil was measured using gas chromatography ECD, the content decreased to below the detection limit of 0.5 ppm, and the water content also decreased from 10 ppm to 8.3 ppm.
m. Also, the volume resistivity at 80°C is 8
．． 2. Much higher than OX 1014Ω・σ (contaminated oil).
IX improved to 1015Ω・all (refined oil). It was confirmed that the various properties required for other insulating oils were not substantially impaired and that it could be fully reused as a recycled electrical insulating oil.

Example 2 In Example 1, the above nickel was used as a dechlorination catalyst.
Contaminated insulating oil was purified using exactly the same procedure and treatment except that a molybdenum-based catalyst was used.

Analysis by gas chromatography ECD revealed that the amount of organic chlorine compounds in the purified insulating oil had been reduced to 0.5 ppm or less. In addition, various electrical insulation properties, especially the volume resistivity at 80°C, were improved to 2.9XIO"Ω·■, and it was confirmed that all other performances specified in JISC2320 were met.

Example 3 The same contaminated insulating oil was treated with N in the same manner as in Example 1, except that the nickel/platinum catalyst was used as the dechlorination reduction catalyst.
Manufactured.

The volume resistivity of the refined remanufactured oil at a temperature of 80° C. was 2.5×10”Ω·■, and it could be used as a recycled M edge.

〔Effect of the invention〕

According to the method of the present invention, contaminated electrical IM containing organochlorine compounds, peroxides, and other impurities! It is possible to highly and effectively remove and purify the oil edges and their impurities. In addition, refined insulating oil is M! ! , the insulation properties desirable for edge bending are significantly improved, and other JIS
It fully satisfies the various properties required for an insulating oil as defined in 2006, and can be reused as a recycled electrical insulating oil, so its industrial value and effective resource utilization are extremely high.

Further, the method of the present invention has excellent practicality because it has no risk of causing secondary pollution, and does not cause air pollution or other environmental problems.

Patent applicant: Nikko Niscy Co., Ltd. Agent/Patent Attorney Ryo Yamamoto -- Kaneji Arai --

Claims (1)

[Claims] 1. Electrical insulating oil containing organic chlorine compounds as impurities is dechlorinated in a hydrogen gas atmosphere in the presence of a zeolite/nickel catalyst or a base metal catalyst with a skeleton of nickel/molybdenum or nickel/platinum and under heating conditions. A method for refining electrical insulating oil.