JPH0770424B2 - Improved oil immersion condenser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an electrical insulating oil obtained by subjecting a by-produced oil fraction, which is a by-product of the production of ethylbenzene, ethyltoluene, cumene, etc., to a liquid-liquid contact with a polar solvent. It relates to an oil-immersed condenser impregnated with the composition.

[Prior Art and its Problems] It has been conventionally known that a heavy by-product oil is by-produced when ethylbenzene, ethyltoluene and the like are produced by alkylating benzene and toluene with ethylene.

For example, in JP-A-54-23088, for example, a by-product oil in the production of ethylbenzene in which benzene is alkylated with ethylene using an aluminum chloride catalyst is disclosed, and in JP-A-61-230.
Japanese Patent Publication No. 16410 discloses that a synthetic zeolite catalyst is used as an electrically insulating oil, which is a by-product oil in the production of ethyltoluene by alkylating toluene with ethylene.

On the other hand, in recent years, there has been a remarkable trend toward miniaturization and weight reduction of oil-impregnated electric devices such as oil-impregnated capacitors, and in response to this, plastic materials as insulators or dielectrics have been developed, and insulating paper that has been conventionally used. It is now used together with or instead of insulating paper.

With regard to the electrically insulating oil for impregnating oil-impregnated electric equipment, various problems have arisen with the use of the above plastic material. That is, conventional electrical insulating oils, for example, refined mineral oil, polybutene, alkylbenzene, etc., are not necessarily compatible with plastic materials such as polypropylene, polymethylpentene, polyolefins such as polyethylene used in the oil-impregnated electrical equipment. I'm not satisfied. Conventional electrical insulating oils may dissolve or swell these plastic materials and reduce the dielectric strength of oil-impregnated electrical equipment.

The electrical insulating oils described in the above publications are not preferable from the above viewpoint. For example, JP-A-61-16410, which discloses by-product oil of ethyltoluene, describes that it has excellent compatibility with plastic materials, but it is not necessarily at a satisfactory level. is not.
There are various causes for this, and one of them is that it is a by-product, and it contains many structurally unidentified substances without fail, that is, no matter how it is distilled. However, it has been found by the present inventors that a certain component therein reduces the electrical properties of the by-product oil, for example, compatibility with plastic materials.

The above components cannot be characterized by structure or completely removed by distillation.

[Structure of the Invention] In view of the above-mentioned circumstances, the present inventors have completed the present invention as a result of research to remove undesired components in the by-product oil and thereby improve the electrical characteristics of the by-product oil. It is a thing.

That is, the present invention is to alkylate benzene or toluene with ethylene using an alkylation catalyst to obtain an alkylated product consisting of unreacted benzene or unreacted toluene, ethylbenzene or ethyltoluene, polyalkylbenzene and heavy components. Mainly contains components with a boiling point (at atmospheric pressure) in the range of 260 to 330 ° C, which is produced by distilling off unreacted benzene or unreacted toluene, ethylbenzene or ethyltoluene and most of polyalkylbenzene from the chemical reaction product. An electrically insulating oil composition obtained by bringing a by-produced oil fraction into liquid-liquid contact with an organic polar solvent, which is 120 to 155 as a chemical shift of a spectrum measured by a C ¹³ NMR method.
The total area intensity of the spectrum of the area intensity in ppm (0
˜155 ppm) to an oil-immersed capacitor impregnated with an electrical insulating oil composition having a ratio of 70% or more.

The present invention will be further described below.

It is industrially performed on a large scale to alkylate benzene, toluene and the like with ethylene and the like by an alkylation catalyst to produce ethylbenzene and ethyltoluene which are petrochemical raw materials. The by-product oil used in the oil-immersed condenser of the present invention is exemplified as a by-product oil produced as a by-product in such a manufacturing process.

More specifically, the above alkylation is usually
It is carried out by a liquid phase alkylation method or a gas phase alkylation method. In the case of the liquid phase alkylation method, Friedel-Crafts catalyst such as aluminum chloride and Bronsted acid such as sulfuric acid, toluenesulfonic acid, hydrofluoric acid and the like are used, and in the gas phase alkylation method, synthetic zeolite, for example, , ZSM-5, phosphoric acid supported on an appropriate carrier, and the like are used. The reaction temperature is usually 20 in the liquid-phase alkylation method.
~ 180 ° C, and in the gas phase alkylation method, it is selected in the range of 250 to 450 ° C.

After the alkylation reaction, in addition to unreacted benzene or toluene, the target products such as ethylbenzene and ethyltoluene, etc., polyalkylbenzene other than ethyltoluene such as polyethylbenzene and polyethyltoluene, and alkylation of heavier heavy components The product is obtained. If necessary, the catalyst is removed from the alkylated product, and the product is neutralized and washed with water. Next, unreacted benzene or toluene, target ethylbenzene, ethyltoluene, and most of polyethylbenzene, polyalkylbenzene other than ethyltoluene such as polyethyltoluene, etc. are distilled from the alkylated product under reduced pressure or atmospheric pressure. By distillation, a by-product oil fraction is obtained.

The by-product oil fraction for use in the oil-immersion condenser of the present invention is a by-product oil fraction mainly containing a component having a boiling point (normal pressure conversion) in the range of 260 to 330 ° C.

Depending on its boiling point, this by-product oil fraction contains some polyethylbenzene, polyethyltoluene, polyisopropylbenzene, polyisopropyltoluene, etc., but other indeterminate analysis is not possible. It is presumed to be a hydrocarbon mixture containing a diaryl or triarylalkane derivative and a polyalkylpolyphenyl derivative.

When the above-mentioned by-product oil fraction contains components below 260 ° C and 330
In the case of containing a component exceeding ° C, the electrical characteristics of the by-product oil fraction are not improved and the level of the electrical characteristics is low even in the case of the liquid-liquid contact in the present invention.

Note that the alkylated product also contains extremely heavy heavy substances such as tar-like substances, but these tars are removed by making the fraction into the above boiling point range.

As described above, the by-product oil fraction thus obtained does not always have satisfactory performance for impregnation of oil-impregnated electric equipment, because of a part of the structure-unconfirmed substance contained therein.

Therefore, in the present invention, the by-product oil fraction is brought into liquid-liquid contact with the organic polar solvent. By doing so, the electric characteristics of the by-product oil fraction are significantly improved. The organic polar solvent used for this liquid-liquid contact preferably has a solubility parameter of 5.1 (J / m ³ ) ^1/2 × 10 ^-3 or more.

Specifically, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol and furfuryl alcohol, ethylene glycol, propylene glycol,
Dietylene glycol, triethylene glycol and other glycols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and other cellosolves, and others, sulfolane, dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), dimethylformamide (DMF) ) Etc. are illustrated. These may be used alone or in combination. Further, it is preferable to add an appropriate amount of water because the contact efficiency is further improved.

The by-product oil fraction is brought into liquid-liquid contact with the polar solvent. Specific operations of liquid-liquid contact include, for example, liquid-liquid extraction or extractive distillation.

In liquid-liquid extraction with a polar solvent, the electrically insulating oil is recovered as an extract. Therefore, after extracting with a polar solvent, the electrically insulating oil is recovered by separating the polar solvent by an appropriate method such as distillation or addition of a third component.

The liquid-liquid contact in the present invention should be clearly distinguished from the mere solvent refining performed on the mineral oil-based electric insulating oil in that the electric insulating oil is recovered as an extract.

The liquid-liquid extraction method can be carried out by using an apparatus such as a normal batch type or continuous type countercurrent extraction column, a multistage extraction tank and the like. After the liquid-liquid extraction, the polar solvent is separated and removed according to a conventional method to obtain an electrically insulating oil.

In addition, extractive distillation can be performed by adding the polar solvent to the by-product oil fraction and performing a conventional extractive distillation method.

In liquid-liquid contact with a polar solvent, the composition of the obtained oil varies depending on the type of polar solvent used and other conditions. For example, in liquid-liquid extraction, it is the extraction temperature, the amount of polar solvent used with respect to the by-product oil fraction, and the like. For example, the extraction temperature is usually selected in the temperature range of 10 to 150 ° C., and the amount used is in the range of 1 to 30 parts by weight of the polar solvent to 1 part by weight of the secondary oil fraction. In the extractive distillation, a polar solvent is mixed in an amount of 1 to 30 parts by weight per 1 part by weight of the by-product oil fraction, and the number of separation stages is preferably 2 under a reduced pressure of 100 mmHg or less.
It is usually performed by 0 or more.

In the present invention, in any case, the above-mentioned liquid-liquid contact operation conditions are appropriately selected, and the obtained electrical insulating oil composition has a chemical shift of 120 as a chemical shift of a spectrum measured by a C ¹³ NMR method. The ratio of the area intensity at ~ 155ppm to the total area intensity of the spectrum (0 ~ 155ppm) is 70
% Or more, preferably 72% or more is important.

As described above, the by-product oil fraction of the present invention is a hydrocarbon mixture that also contains a substance whose structure cannot be identified. It will not be removed. By specifying the ratio of the area intensity by the C ¹³ NMR method, undesired components in the structure-unknown component are excluded, and a synergistic effect is exhibited by the interaction of each remaining component, which has excellent electrical characteristics. This is an electric insulating oil.

The conventional solvent refining of insulating oil is generally distinguished from the present invention in that it is aimed at raffinate as described above, and its purpose is to reduce the aromatic content. As a result rather enhances aromaticity and should also be distinguished in this respect.

Here, the measuring method by the C ¹³ NMR method will be described. The measurement temperature is usually room temperature. The fraction as the sample to be measured has a concentration of 10
Dissolve it in deuterated chloroform as a measuring solvent so that the concentration becomes ~ 20% by volume. The measurement frequency can be changed appropriately,
For example, 67.8 MHz. In the obtained C ¹³ NMR spectrum, the chemical shift based on tetramethylsilane was 12
The area intensity between 0 and 155 ppm is determined, and the ratio (%) of this value to the total area intensity, which is the sum of the area intensities of all spectra (0 to 155 ppm) excluding the solvent, is determined. The first digit after the decimal point of this value is rounded off. In order to improve the quantitative property, the measurement is usually carried out by the complete proton decoupling method eliminating the nuclear Overhauser effect.

The electrical insulating oil produced as described above is refined as necessary and used as an impregnating oil for an oil immersion capacitor.

Further, it can be used by mixing with a conventionally known electric insulating oil, for example, sialylalkane, alkylbiphenyl, alkylnaphthalene, etc. at an arbitrary ratio depending on the application and the like.

The oil-immersion capacitor of the present invention is an oil-immersion capacitor in which at least a part of the dielectric is made of plastic.
Polyolefins such as polyethylene and polymethylpentene are preferable as the plastic, and polypropylene is more preferable. For example, the oil-immersed capacitor of the present invention is produced by winding a polypropylene film together with an insulating paper, if necessary, together with a metal foil such as an aluminum foil as a conductor, and impregnating the electrically insulating oil according to a conventional method. You can An oil-immersed capacitor obtained by winding a metallized plastic film such as a metallized polypropylene film together with an insulating paper or a plastic film and impregnating it with an electrically insulating oil is also included in the above-mentioned suitable capacitor.

[Effect of the present invention] The physical properties of the by-product oil fraction, which is not suitable for impregnation in oil-immersed condensers using plastics, are remarkably improved, and the electric insulating oil impregnated in the present invention is used. Oil-impregnated capacitors have excellent corona discharge characteristics and low temperature special properties.

The present invention will be described in detail below with reference to examples.

[Example] (By-product oil fraction A) From the step of producing ethylbenzene by alkylating benzene with ethylene by a liquid phase alkylation method using an aluminum chloride catalyst, 43.0% by weight of unreacted benzene,
An alkylated product consisting of 11.8% by weight of ethylbenze, 18.3% by weight of polyethylbenzene and 7.6% by weight of heavier heavies was obtained. Unreacted benzene, ethylbenzene and polyethylbenzene were distilled off from this alkylated product by distillation. The residual by-product oil was a black, viscous substance containing tar-like substances. This is further distilled under reduced pressure,
By-product oil fraction A shown in Table 1 was recovered.

(By-product oil fraction B) Synthetic zeolite ZSM-5 (H ⁺ type, silica / alumina ratio (mol) = 60) was used as a contact, and at a reaction temperature of 450 ° C, toluene was alkylated with ethylene to give ethyltoluene. An alkylated product containing unreacted toluene, ethyltoluene, polyethyltoluene and by-product oil was obtained from the step of producing. From this alkylated product, a fraction containing unreacted toluene, ethyltoluene, and polyethyltoluene having a boiling point of less than 250 ° C. was distilled off to recover a by-product oil. Then, a by-product oil fraction B having a boiling point range shown in Table 1 was obtained from this by-product oil.

(Liquid-Liquid Extraction) Extraction Method I: A polar solvent and a by-product oil fraction were mixed at a weight ratio of 1: 1 and shaken well in a separatory funnel, and then raffinate (extraction residual liquid) was removed. Then, by washing with n-hexane, the oil component from which the polar solvent has been removed is recovered as a raffinate. By repeating this operation three times, an electrically insulating oil is obtained.

Extraction Method II: The polar solvent and the by-product oil fraction are mixed at a weight ratio of 1: 1 and shaken well in a separating funnel to remove the raffinate and then the flash solvent to remove the polar solvent. By repeating this operation three times, the electrical insulating oil is recovered from the by-product oil fraction.

(Measurement by C ¹³ NMR method) With a GX-270 type C ¹³ NMR measuring device manufactured by JEOL Ltd.,
15% concentration of each fraction in deuterated chloroform as solvent
Was dissolved in the solution and measured at room temperature.

Observation frequency: 67.8 MHz In order to improve the quantitativeness, the measurement was carried out by the complete proton decoupling method in which the nuclear Overhauser effect was eliminated.

In C ¹³ NMR spectra, chemical shifts 120~155ppm
The ratio of the area intensity in the above to the total area intensity (0 to 155 ppm) was determined for each fraction. The results are shown in Table 1.
Chemical shifts were based on tetramethylsilane.

(Compatibility with polypropylene film) Polypropylene film (thickness 14
Micron) for 72 hours at 80 ° C in each fraction,
The film was taken out and the swelling ratio (%) of the film before and after immersion was measured. The results are shown in Table 2. The smaller the value, that is, the smaller the value of the film swelling rate,
Since it does not swell the film and has excellent dimensional stability,
It can be said that the compatibility with the polypropylene film is good.

(Measurement of corona onset voltage: CSV and corona extinction voltage: CEV) By using two 14-micron-thick polypropylene films as a dielectric, and winding and laminating an aluminum foil as an electrode according to a conventional method. , A model condenser for oil impregnation was created.

This condenser was impregnated with each fraction under vacuum to prepare an oil-impregnated condenser having a capacitance of 0.4 microfarads.

The corona onset voltage and the corona extinction voltage at -35 ° C of these capacitors were measured. The results are shown in Table 2.
Shown in.

(Capacitor life test) A model capacitor for oil impregnation is created by using two 14-micron-thick polypropylene films as a dielectric and winding and laminating aluminum foil as an electrode according to the usual method. did.

This condenser was impregnated with each fraction under vacuum to prepare an oil-impregnated condenser having a capacitance of 0.4 microfarads.

Next, a predetermined AC voltage was applied to these capacitors at -35 ° C, and the life of the capacitors was determined by measuring the time until the capacitors were destroyed. In that case, the potential gradient was increased at a rate of 10 V / μ every 48 hours from the potential gradient of 80 V / μ, and the number of broken capacitors was examined. The initial number of capacitors was 10 each. The results are shown in Table 2.

Claims (5)

[Claims] 1. Alkylation of benzene or toluene with ethylene in the presence of an alkylation catalyst, and production by distillation from unreacted benzene or unreacted toluene, ethylbenzene or ethyltoluene, an alkylation product consisting of polyalkylbenzene and heavy components. By-product oil fraction mainly containing components in the range of boiling point (converted to normal pressure) 260 to 330 ° C. is recovered as an extract by bringing the organic polar solvent into contact with the liquid-liquid, and extracting the organic compound from the extract. The composition obtained by removing the polar solvent, and the ratio of the area intensity at 120 to 155 ppm as the chemical shift of the spectrum measured by the C ¹³ NMR method to the total area intensity (0 to 155 ppm) of the spectrum is Characterized by being impregnated with an electrical insulating oil composition obtained by selectively recovering 70% or more An oil-immersed condenser. 2. The solubility parameter of the organic polar solvent is
5.1 (J / m ³ ) ^1/2 × 10 ^-3 or more, The oil immersion condenser of Claim 1 characterized by the above-mentioned. 3. The organic polar solvent is a lower alcohol such as methanol or ethanol, a cellosolve such as methyl cellosolve, a glycol such as diethylene glycol or triethylene glycol, dimethyl sulfoxide (DM).
The oil-immersed condenser according to claim 1 or 2, which is a solvent selected from SO), N-methylpyrrolidone (NMP), sulfolane, hydrates thereof, and mixtures thereof. 4. An insulating material or a dielectric material, at least a part of which is made of plastic.
The oil-immersed condenser according to any one of paragraphs. 5. The oil-immersed capacitor according to claim 4, wherein the plastic is polyolefin.