JPH01161090A - Production of insulating oil - Google Patents

Abstract

PURPOSE:To advantageously prepare an insulating oil having excellent low-temp. characteristics, by hydrotreating a deasphalted oil derived from a paraffin base crude oil or a mixed base crude oil, dewaxing the deasphalted oil, conducting solvent extraction of the dewaxed oil to obtain an extract oil, and treating the extract oil with an adsorbent. CONSTITUTION:A lubricating oil fraction collected from a paraffin base crude oil or a mixed base crude oil, or a deasphalted oil obtd. by deasphalting the aforesaid crude oil is hydrotreated or extracted and then hydrotreated (first step). The hydrotreated oil is dewaxed (second step). The dewaxed oil is extracted with a solvent having a selective affinity for an arom. hydrocarbon (e.g., furfural) to collect an extract oil having a fluid point of -30 deg.C or below and an n-d-M ring analysis value(%) CA of 10 or more (third step). This extract oil is adsorbed on a solid adsorbent (e.g., activated clay) (fourth step.) Thus, it is possible to advantageously prepare an insulating oil having excellent low temp. characteristics and high aromaticity which has been prepared in the art with great difficulty.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing highly aromatic electrolytic oil having excellent low temperature properties from paraffin base crude oil or mixed base crude oil.

Electrical insulating oil used in assembly at low temperatures between -30 and -60℃
Because it has a low pour point and is used under a high electric field, it is required to have the property of absorbing the hydrogen gas generated when partial discharge occurs (hydrogen gas absorbency). of base oil is required.

Conventionally, electrical insulating oils with the above-mentioned properties have been produced from naphthenic crude oil or highly aromatic synthetic oils such as alkylbenzene have been used, but recently there has been a rise in the difficulty in obtaining naphthenic crude oil, and Due to the high price of synthetic oil, there has been a demand for the establishment of a technology to produce electrical insulating oil with the above-mentioned high aromaticity and low pour point performance from paraffin base crude oil or mixed base crude oil. There is still no proposal for a satisfactory technique.

In general, when a lubricating oil fraction is hydrorefined and dewaxed under harsh conditions, the pour point is approximately -10 to -30°C.
Although it is possible to obtain a base oil with a ndM ring analysis value of %CA of about 4 to 8, it is actually difficult to obtain a base oil with a lower pour point and high aromaticity. be.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art. is pour point -3
An object of the present invention is to provide a method for efficiently producing electrical insulating oil having properties of 0°C or lower, preferably -35°C or lower, and an nd-M ring analysis value %CA of 10 or higher, preferably 15 or higher. do.

The present invention will be explained in detail below.

A feature of the present invention is that the lubricating oil fraction collected from paraffin base crude oil or mixed base crude oil or the deasphalted oil obtained by deasphalting the above crude oil is subjected to hydrotreating or solvent extraction. A first step of treatment and hydrogenation, a second step of dewaxing the hydrogenated oil, and a solvent extraction of the dewaxed oil with an 'A' aromatic hydrocarbon and a selectively compatible solvent. Pour point below -30°C after treatment n - d -) 1 tQ analysis Plant %C1
The method for producing electrical insulating oil includes a third step of collecting 10 or more extract oils, and a fourth step of adsorbing the extract oils.

Means for Solving the Problems The crude oil used in the present invention is paraffin base crude oil or mixed base crude oil extracted in the Middle East, China, and Southeast Asia. The deasphalted oil obtained by deasphalting the crude oil is used as a raw material for lubricating oil base oil. That is, the residual oil of the above-mentioned crude oil is distilled under reduced pressure, and the boiling point is about 250-400°C.
, about 350 to about 500°C, and about 450 to about 650°C, or deasphalted oil obtained by deasphalting the above-mentioned distillation residue using propane or the like is used as the raw material. In addition, if necessary, the distillate or deasphalted oil obtained as described above may be further distilled to reduce the viscosity level, for example, the viscosity at 40'C is 5 to 500 cst. One having a desired viscosity is appropriately selected and used.

In the present invention, the target electrical insulating oil is obtained by refining the above-mentioned raw material oil according to the procedure shown below.

In the present invention, in the first step, the raw material oil is hydrotreated or subjected to hydrogenation treatment and solvent extraction treatment to obtain hydrogenated oil or hydrogenated raffinate oil.

If hydrogenation and solvent extraction are carried out in combination, either of them may be carried out first, but the solvent extraction should be carried out first to separate the extracted oil and then the hydrogenation should be carried out. This is more practical as it requires less oil in the sump for hydrotreating.

In the above hydrogenation treatment, a known hydrorefining catalyst such as Ni, Co, Mo5W, Ti, V, etc. is used.
About 0.1 to about 10-t% of the species or two or more species are supported on a single body of silica, alumina, silica-alumina, etc., at a hydrogen pressure of about 30 to 150 kg/c (G) and a temperature of about It is carried out by contacting with feedstock oil at 300 to about 450°C and a liquid hourly space velocity of 0.2 to 5 hr-', and the sulfur content of the hydrogenated oil obtained is actually 1 wt% or less, preferably Q, 5 wt% or less. It is a good idea to select such conditions. In addition, when carrying out a combination of solvent extraction treatment and hydrogenation treatment, a known solvent such as furfural, phenol, N-methyl-2-pyrrolidone, etc. is used, and the raffinate is brought into contact with the raw material oil at a temperature of 40 to 80 °C. A portion may be taken and desolvated to obtain a raffinate oil, which may be hydrotreated as described above.

The hydrogenated oil or hydrogenated raffinate oil thus obtained is subjected to a solvent film waxing treatment as a second step. For solvent membrane brazing, a mixture of acetone or methyl ethyl ketone/toluene) is mixed with the hydrogenated oil or hydrogenated raffinate oil at a volume ratio of 2/1 to 3/1.
Cool to -20°C, or below -20°C if necessary, and filter the precipitated wax to separate it from the oil to collect the dewaxed oil.

The pour point of the dewaxed oil obtained here is -10 to -20"C
Although it is preferable to select a pour point within the range of 1 to 1, the pour point may actually be determined depending on the intended use of the lubricating base oil, and therefore may be set to -20°C or lower. However, due to the solvent extraction treatment that is performed on this dewaxed oil as described below, the pour point of the resulting extract oil is significantly lowered than expected. It is not necessary to set harsh dewaxing conditions to be able to reduce the dewaxing conditions.

In the present invention, as a third step, the dewaxed oil as described above is extracted using a solvent that has a selective affinity for aromatic hydrocarbons to obtain an extract oil. The above solvents include furfural, phenol, N
-Methylpyrrolidone is an example, and these may be used alone or in combination of two or more.

In order to extract the dewaxed oil using this solvent, it is best to bring the dewaxed oil and the solvent into contact at a temperature of 60 to 120°C at a solvent/oil stopper (volume ratio) of 1/1 to 3/1. In the present invention, the extract obtained by this contact is collected, the solvent is removed, and the extract is collected as an extract oil. Here, the yield of extract oil is 5 to 30 vol%, preferably 5 vol.
It is desirable to select the extraction conditions so that the result is ~25vO1% in order to achieve the desired pour point of -30°C or lower.

The above solvent extraction process yields an extract oil with a very low pour point. For example, the pour point is -10 to -15
When dewaxing oil at ℃ is subjected to solvent extraction treatment, -30 to -60
Extract oil with a pour point of ℃ can be easily obtained.

In this way, the pour point reduction due to solvent extraction treatment is achieved through a series of steps consisting of dewaxing treatment (second step) in advance, extraction treatment with a specific solvent, and extract oil collection (third step). This can be achieved by processing. Furthermore, when processed through the above series of steps, n-d-M
Products with a ring analysis value %CA of 10 or more, and even 15 to 50, can be obtained without severe hydrogenation or severe dewaxing treatment.

In the fourth step of solid adsorption purification of the extract oil obtained by the solvent extraction treatment using a solid adsorbent such as activated clay, nitrogen components are removed and an oil with a stable hue is obtained. Incidentally, the raffinate oil obtained simultaneously with the extract portion in the solvent extraction process can be used as a general-purpose lubricating oil base oil such as motor oil by ordinary refining process.

As mentioned above, the present invention performs hydrogenation treatment or solvent extraction treatment and hydrogenation treatment on the raw material oil, then dewaxes the obtained oil, and then performs solvent extraction treatment to improve low-temperature characteristics. This method succeeded in obtaining a highly aromatic base oil, and instead of using a process consisting of a series of steps as described above, a solvent extraction process was performed prior to the dewaxing process, and then the obtained base oil was The order in which the solvent dewaxing treatment is performed on the extracted extract oil causes clogging during the filtration operation during the dewaxing treatment, which interferes with the filtration separation of the precipitated wax. As a result, it becomes impossible to obtain oil with a low pour point as described above.

The present invention and its effects will be specifically explained below using Examples and Comparative Examples.

Example 1 The residual oil obtained by distilling Arabian light crude oil under atmospheric pressure was distilled under reduced pressure to distill distillate A with a boiling point of 250 to 400°C and distillate oil A with a boiling point of 250 to 400°C.
Distillate oil B at 520°C and distillate oil C at 400 to 650°C were collected and used as raw material oils, respectively.

Distillate oil A was sequentially purified by the following operations according to the process diagram shown in the attached Figure 1.

First, distillate A is fed into a high-pressure hydrogenation equipment filled with a Co-Mo hydrotreating catalyst at a hydrogen pressure of 100 kgf/cffl.
(G), liquid hourly space velocity (
LIISV) 1, supplied with Ohr-' and hydrogenated,
Sulfur content 0. ht% of hydrotreated oil was obtained.

Next, toluene/methyl ethyl chloride was added to the hydrogenated oil A.
- Add 2 parts by volume of a mixed solvent (50150 volume ratio) to 1 volume of oil, cool to -30°C and leave for half an hour, then filter the precipitated wax with a filter cloth and remove the wax from the dewaxed oil. A was collected. The pour point of the obtained dewaxed oil A was -15°C.

Next, using a rotating plate type countercurrent contact extraction device, 2 parts by volume of furfural were added to 1 part by volume of the above dewaxed oil A, and solvent extraction was performed at a temperature of 60 to 80°C to separate the extract part and the raffinate part, respectively. Furfural was separated from the extract by vacuum evaporation to obtain extract oil A. The yield of the obtained extract oil A based on the dewaxed oil was 15vol%.

Next, 2.5wt of activated clay was added to this extract oil A.
% and stir to perform adsorption treatment to obtain the desired electrical insulating oil A.
I got it.

The properties of the kernel oil are shown in Table 1. The properties of the dewaxed oil A are also shown for reference.

Table 1 Example 2 Distillate oil B and distillate oil C shown in Example 1 were
Purification treatments were performed by the following operations according to the steps shown in the figure.

Using a rotating plate type countercurrent contact extraction device, 2.0 parts by volume of furfural was added to each distillate oil per 1 part by volume of oil.
℃ temperature, the raffinate portion was collected, and the solvent was removed under reduced pressure to obtain raffinate oils B and C.

Next, using a hydrogenation apparatus filled with the same catalyst as described in Example 1, a hydrogen pressure of 100 kgf/c11! (G),
Temperature 370-375°C (for raffinate oil B), 3
Hydrogenation treatment was performed at 80 to 385°C (in the case of raffinate oil C) to obtain hydrogenated raffinate oils B and C with a sulfur content of 0.1 wt%.

Next, each of the hydrogenated raffinate oils was dewaxed in the same manner as described in Example 1 to obtain dewaxed oils B and C with pour points of -15°C. 2.5 parts by volume of furfural per 1 part by volume of the dewaxed oil was added to each of the obtained dewaxed oils, and an extraction process was performed at a temperature of 80 to 100°C using the same extraction apparatus as described in Example 1 to obtain extra The extract was separated into a raffinate portion and a raffinate portion, and the extract portion was desolventized to collect extract oil B and extract oil C.

The yield of each extract oil obtained relative to the dewaxed oil was 7. Ovo1%, C oil 12. Ovo was 1%.

Then, for each extract oil, activated clay 5, Owt.
% was added and adsorption treatment was performed to obtain electrical insulating oils B and C. Their properties are shown in Table 2.

Next, as a comparative example, a case where purification was performed by changing the processing order without adopting the series of process treatments according to the present invention will be shown.

Comparative Example Hydrogenated oil A, which had been hydrotreated according to Example 1, was subjected to solvent extraction treatment using a rotating plate type countercurrent contact extraction device according to the same procedure as described in Example 1, and from the obtained extract portion. The extract oil was collected by removing the solvent. Next, 2 parts by volume of a mixed solvent of toluene/methyl ethyl ketone (50150 volume ratio) was added to this extract oil per 1 part by volume of the oil, and after cooling to -30°C and leaving for half an hour, the precipitated wax was filtered through a filter cloth. was filtered to obtain dewaxed oil A'.

Add activated clay to this dewaxed oil A'.5. ht% was added and adsorption treatment was performed to obtain electrical insulating oil A'.

The properties of the obtained base oil A' are as shown in Table 3.

Table 3 Example 3 This example shows the functional characteristics of the electrical insulating oil obtained according to the present invention.

Electrical insulating oil A obtained in Example 1 and A obtained in Comparative Example
Table 4 shows the results of measuring the functional properties as an electrical insulating oil.

As a reference, Table 4 also shows the results of measurements made in the same manner for electrical insulating oil using naphthenic crude oil.

Effects of the invention As seen in Tables 1 and 2, according to the present invention,
When the pour point of dewaxed oil is -115°C, the pour point of electrical insulating oil obtained by solvent extraction is -30 to -50°C.
℃ to obtain the desired cold-flowing oil.

Furthermore, as shown in Table 4, the electrical insulating oil obtained according to the present invention has electrical properties such as dielectric breakdown voltage, volume resistivity, and dielectric loss tangent that are equivalent to commercial oil, but it cannot be used under high electric fields. The specific dispersion and hydrogen gas absorption properties, which indicate the difficulty of corona discharge in the case of oil, are extremely superior to commercially available oils, making it possible to use higher voltage equipment.

On the other hand, although the base oil obtained in the comparative example has excellent corona discharge resistance, it has a high pour point, JISC2320
Even at temperatures below the standard of -27.5°C, it is unusable.

As mentioned above, according to the present invention, it is possible to advantageously produce electrical insulating oil with excellent low-temperature properties and high aromaticity, which was conventionally difficult to produce from paraffin-based or mixed-base crude oil. There are advantages.

[Brief explanation of the drawing]

The attached FIGS. 1 and 2 illustrate process diagrams for producing electrical insulating oil according to the present invention. Applicant: Kyoseki Product Technology Research Institute Co., Ltd.

Claims (1)

[Claims] (1) A first step in which the lubricating oil fraction collected from paraffin base crude oil or mixed base crude oil or the deasphalted oil obtained by deasphalting the above crude oil is subjected to hydrotreating or solvent extraction treatment and hydrotreating. a second step of dewaxing the hydrotreated oil; a solvent extraction treatment of the dewaxed oil with a solvent that has selective affinity for aromatic hydrocarbons to obtain a pour point of -30°C or lower n-d; - A method for producing electrical insulating oil, comprising a third step of collecting extract oil having an M ring analysis value of %C_A10 or more, and a fourth step of adsorbing the extract oil.