DE1050482B - - Google Patents

Description

GERMAN

Cable impregnation oils must have a high viscosity of at least 20 ° E at normal temperature at 50 ° C to prevent the oil from migrating in the cable. At the same time their viscosity index should be low in order to allow the cable to be impregnated at only a slightly elevated temperature. Furthermore, such oils have good electrical properties, good gas resistance and high Stability required. The carefully refined mineral oils previously used for this special purpose had to be used to achieve the desired viscosity properties, for example with resins, polymerized fission products, microcrystalline waxes and possibly mineral oil extracts which resulted in various disadvantages in practical use.

It has now been found that Kabelimprägnieröle can be obtained with excellent properties directly from mineral oils, by starting from a mineral oil fraction having a viscosity of ao at least 20 ° E at 50 ° C and an aromatic content of at least 50 weight percent, and this fraction first with strong sulfuric acid , Treated oleum or sulfur trioxide, neutralized the oil after separating the acid tar with a basic compound and then or simultaneously distilled, whereupon it is treated with a solid adsorbent.

According to a particular embodiment of the method, you can also use any Mineral oil fraction run out, provided that this is only a partial fraction with a viscosity of at least 20 ° E at 50 ° C and this partial fraction has an aromatic content of at least 50 percent by weight. The starting material is subjected to the acid treatment and neutralized; during the Destination is then separated the desired partial fraction, and this is finally with the fixed Treated adsorbent.

The mineral oil fraction used as the starting material can pass through in a manner known per se Distillation, either as a distillate or as a residue, can be obtained from a crude oil. Naphthenic or asphalt-based crude oils are very suitable. The relatively high aromatic content of the The starting material ensures good gas resistance and a low viscosity index of the end product. Under the aromatic content of a mineral oil fraction, that which is soluble in strong sulfuric acid becomes Understood part of the oil which is determined by the method described in more detail in Example I £ °.

The treatment with strong sulfuric acid, oleum or sulfur trioxide is carried out continuously or discontinuously in a manner known per se
of cable impregnation oils

Applicant:
Deutsche Shell AG _r Hamburg 36

Dr. Hans Seeles ₁ Hamburg, and Dipl.-Chem. Hans Daily, Hamburg-Harburg, have been named as the inventor

leads. One uses z. B. concentrated sulfuric acid (70 to 100 _{% H 2} SO ₄ ) or oleum (up to 30Vo SO ₃ ) in amounts of 5 to 30 percent by weight, calculated on the amount of oil treated. Sulfur trioxide is generally used in somewhat smaller amounts.

After the acid tar formed has been separated off, the oil is neutralized _{with a basic compound such as NaOH or Ca (OH) 2.} The basic compound can be used in dry form or as a solution or suspension (e.g. in oil, water and / or alcohol). Preferably an excess (e.g. 5 to 40%) of the neutralizing agent is used. The sludge formed during this treatment (so-called alkaline sludge, which consists primarily of salts formed during the neutralization and the excess of the neutralizing agent and possibly contains oil components and / or the solvent or suspending agent for the basic compound) does not need to be separated from the oil, because in the subsequent distillation, the solid fractions of this sludge remain in the distillation residue and any liquid fractions can easily be separated from the oil.

The neutralization can be carried out before or during the distillation. The last method is preferably used because the neutralization reaction often only occurs at higher temperatures runs quantitatively. At the high temperatures that occur in the still, everyone finds it If a complete neutralization takes place, so that there are no more acids in the distillation column itself pull up with the distillate vapors.

809 749/356

The distillation is carried out under reduced pressure, if necessary using steam, made because the oils cannot be distilled without decomposition under atmospheric pressure.

After the distillation, the oil is treated with a solid adsorbent in a manner known per se. Usually, adsorbent earths or clays such as fuller's earth, bauxite and clays are used can be activated by acid treatment, preferably in an amount between 1 and 15 weight percent based on the amount of oil treated. It is beneficial to treat elevated temperature, e.g. B. 70 to 130 ° C to perform.

It should be noted that the procedural steps discussed are essential and are also essential in that indicated Sequence must be carried out.

Without the acid treatment it is e.g. B. not possible to obtain an oil with good properties. Neutralization cannot be omitted either, because otherwise the distillate will contain distilled acids would. The oil-insoluble alkali sludge formed during the neutralization can be caused by phase separation removed. However, oil-soluble impurities such as sulfone soaps then remain in the oil can only be completely removed by distillation. Therefore, the neutralization must take place before or during the distillation can be carried out. After the distillation, the oil already has a very high level Degree of purity, but it does not yet have the required properties to the desired extent. the Post-treatment with the solid adsorbent required for this does not have the desired effect, if it is carried out before or during the distillation.

The stability of the cable impregnation oils obtained by the process according to the invention can still are further improved by the addition of known antioxidants and / or Metal deactivators. These additives are used in small amounts, for example below 1 percent by weight, calculated on the oil used.

Example I.

From a Venezuelan crude oil, lubricating oil fractions with the following properties were distilled out:

Thickness at 20 ° C

Viscosity, ⁰ E at 50 ° C
Flash point

(open cup), ⁰ C ..
Neutralization number

0.945 13.8

149 5.0

0.953 25

144 5.7

These fractions were treated with 8 percent by weight sulfuric acid (97 percent by weight H ₂ SO ₄ ) at a temperature of 70 ° C. After separation of the acid tar, the acid oils had the following properties:

30th

1 2 Viscosity, ^q E at 50 ° C 12.0 19.7 7.1 8.3

The acid oils were mixed with milk of lime (excess 20%, based on the neutralization number of the acid oil) added, and the mixture was then distilled in vacuo, with the following oil fractions were cut out:

Foreign a b C. Density at 20 ° C 0.946 0.947 0.949 Flash point (open crucible), ⁰ C ....
Viscosity, ⁰ E at 50 ° C. . 260 295 302 36 76 112 0.01 0.01 0.01 -5 0 + 5 Aromatic content, 60 65 70

From 2

0.947

268
40

0.01
-5

60

0.949

283
69
0.01
0

0.951

310 143

0.01 + 4

70

0.954

326 248

0.01 + 5

80

The oils A to G were to review of the electrical properties ultimately temperature of 90 ° C with 8 weight percent of bleaching earth and the aging stability of these oils were measured at a tem- 55 Mesbehandelt. the electrical dissipation factor tgA. before and

carried out after artificial aging.

oil
70 ° C a
»/ 0
90 ° C oil
70 ° C f
90 ° C Ό
70 ° C Ig
1 Vo
90 ° C 0.14
0.65
0.28 0.24
1.9
0.65 0.12
0.38
0.20 0.20
1.1. .
0.45 0.10
0.25
. 0.14 0.14
0.75
. 0.30

Before aging ....
After aging *).
Nath of aging **)

*) Pure oil.

**) oil with the addition of 0.05 percent by weight Ν, Ν'-disalicylalethylenediamine. -This addition · has to the loss factor before the Aging no noticeable influence.

15th

The listed. Analysis results were obtained by the following methods.

Density:

According to DIN 53653.

Viscosity:

According to DIN 51550 (Vogel-Ossag).

Flash point (open cup):
According to DIN 53661.

Neutralization number:
According to DIN 53658.

Loss factor:

In the loss factor measuring device (50 Hz) according to Prof. Dr. Schering.

Aging:

According to the “Cables and Insulated Wires ”, the oils were aged for 168 hours at 125 ° C.

Aromatic content:

20 g of the oil to be tested are mixed with 80 ecm of aromatic-free gasoline with a boiling point of 60 to 80 ° C and 110 ecm sulfuric acid (100%) mixed. The mixture becomes a quarter of an hour shaken vigorously. After sitting for 3 hours, the acid tar is drawn off and again with it the same amount of sulfuric acid shaken for 15 minutes. The mixture is left to stand overnight and pulls off the acid tar. The gasoline solution is washed out four times with 25 ecm of alcohol (50%) each time. The third part of alcohol contains a little caustic soda at 4 ° Be. The solvent is now distilled off. After adding a little alcohol, the distillation residue becomes Put in a boiling water bath for 1 hour. Eventually the residue becomes a quarter of an hour dried at 105 ° C and weighed in a desiccator after cooling. From the difference between The aromatic content is calculated from the initial weight and the weight of the residue, in percent by weight is expressed.

Example II

A naphthenic cylinder oil with the following properties:

Density at 20 ° C 0.947

Viscosity, ° E at 50 ° C 38

Flash point (open cup), ⁰ C 260

Viscosity index +5

Aromatic content, weight percent 60

was extracted with 250 percent by volume of liquid sulfur dioxide. There was 35 weight percent extract (calculated on the starting oil). This extract had the following properties:

Density at 20 ° C 1.020

Viscosity, ⁰ E at 50 ° C 245

Neutralization number 0.06

Aromatic content, weight percent 96

The extract was treated with 10 percent by weight (calculated on the extract) of sulfuric acid (80% H ₂ SO ₄ ) at a temperature of 90 ° C. After the acid tar had been separated off, milk of lime (excess 30%, based on the neutralization number of the acid oil) was added to the acid oil, and the mixture was then distilled in vacuo, an average fraction of 85 percent by weight being removed from the extract. This middle fraction was finally treated with 10 percent by weight fuller's earth at a temperature of 120 ° C.

The finished oil had the following properties:

Density at 20 ° C 1.021

Viscosity, ⁰ E at 50 ° C 194

Viscosity, ° E at IOO ⁰ C 5.4

Neutralization number 0.01

Aromatic content, weight percent 90

The results of the loss factor measurements were:

tg Λ o / o

70 ° C 90 ° C 0.10 0.19 0.34 1.37 0.11 0.24

An improvement of the cable impregnation oils produced according to the invention, which are already excellent in themselves can still be achieved by initially using the starting material in a manner known per se Way with a selective solvent for the aromatic components of the oil (e.g. with liquid Sulfur dioxide or furfural) and the extract obtained the four treatments described subject. The cable impregnation oils obtained in this way show excellent electrical properties Properties as well as excellent stability. Thanks to the high aromatic content, they also have a greatly improved gas resistance and a very low viscosity index.

So far, such aromatic-rich extracts, which are mainly obtained during refining of lubricating oil, were either discarded entirely or at most still used as heating oils. According to the method of the invention However, it is possible to convert them into valuable cable impregnation oils, as in the following example explained.

Before aging

After aging *)

After aging **)

*) Pure oil.

**) oil with the addition of 0.05 percent by weight Ν, Ν'-disalicylalethylenediamine.

Oils made from non-extracted starting materials (see Example I) and made from extracts oils (cf. Example II) can be mixed with one another in order to improve the properties of the cable impregnation oils to the desired values.

When refining lubricating oils, it is known per se, treatments with sulfuric acid or Carry out oleum and a subsequent neutralization to then produce the desired light lubricating oil fraction separated by distillation. However, this did not indicate any particular effect of the invention provided four treatment stages for very viscous and aromatic-rich mineral oil fractions on the type of cylinder oils are closed.

One has also benefited from the production of light electrical insulating and transformer oils Raffinates as an admixture already have small amounts of a rich in aromatics, with sulfuric acid and fuller's earth pretreated and neutralized extract

Claims (4)

used. Furthermore, a treatment with sulfuric acid with subsequent distillation and final purification with clay is known for the production of such a raffinate. According to these previously known procedures, however, no products are obtained which are suitable as cable impregnation oils and which can be used as such and without adding other substances which influence the viscosity properties. Patent claims: 1. A process for the production of cable impregnation oils, characterized in that one of a mineral oil fraction with a viscosity of at least 20 ° E at 50 ° C and an aromatic content starting from at least 50 percent by weight and this starting material 1. treated with strong sulfuric acid, oleum or sulfur trioxide, 2. Tfifit ' a basic compound neutralized, 3. distilled and 4. treated with a solid adsorbent,
Treatments 2 and 3 can be performed simultaneously if desired. 2. Modification of the method according to claim 1, characterized in that one Mineral oil fraction used as a starting material, in which a partial fraction with a viscosity of at least 20 ° E at 50 ° C is present, which has an aromatic content of at least 50 percent by weight, and that after the acid treatment (!) And after the neutralization (2) separates the desired partial fraction during the distillation (3) and only this with treated further with the solid adsorbent. 3. Process according to Claims 1 and 2, characterized in that the starting material is first treated with a selective solvent extracted for the aromatic constituents of the oil and the resulting extract den subjects mentioned treatments. 4. A process for the production of cable impregnation oils, characterized in that one oil produced from a non-extracted mineral oil fraction according to claims 1 and 2 with an oil prepared from an extract according to claim 3. ® 809 749/356 2.59