Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
  • H01B3/22—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M101/00—Lubricating compositions characterised by the base-material being a mineral or fatty oil
  • C10M101/02—Petroleum fractions
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/10—Lubricating oil
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/12—Electrical isolation oil
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/1006—Petroleum or coal fractions, e.g. tars, solvents, bitumen used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/102—Aliphatic fractions
  • C10M2203/1025—Aliphatic fractions used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/104—Aromatic fractions
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/104—Aromatic fractions
  • C10M2203/1045—Aromatic fractions used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/106—Naphthenic fractions
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/106—Naphthenic fractions
  • C10M2203/1065—Naphthenic fractions used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/108—Residual fractions, e.g. bright stocks
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/108—Residual fractions, e.g. bright stocks
  • C10M2203/1085—Residual fractions, e.g. bright stocks used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/02—Hydroxy compounds
  • C10M2207/023—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings
  • C10M2207/026—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings with tertiary alkyl groups
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/14—Electric or magnetic purposes
  • C10N2040/16—Dielectric; Insulating oil or insulators
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/14—Electric or magnetic purposes
  • C10N2040/17—Electric or magnetic purposes for electric contacts

Definitions

• This invention relates to improved insulating oils. More particularly, it relates to a process for preparing electrical insulating oils which are oxidation stable, nonsludging, and resistant to gassing.
• hydrocarbon oils are used in electrical applications such as transformers, circuit breakers, and high voltage cables because of their high dielectric strength.
• hydrocarbon oils for electrical applications must be carefully refined.
• the high electrical stress to which insulating oils are subjected also tends to decompose the oil thus producing sludge and gaseous products which may cause serious damage and failure of the apparatus in which they are used.
• the presence of aromatic hydrocarbons in the oil tends to inhibit such decomposition (gassing), but they have an adverse effect in that they increase oxidative sludging.
• Mineral oils having a viscosity of between about 1 and 9 degrees Engler at 20 C. are generally used as dielectric oils in electrical equipment.
• the starting material is usually a straight-run mineral oil distillate of the above viscosity.
• Usual refining methods are extraction with a selective solvent for the aromatic components of the oil (e.g., liquid sulfur dioxide or furfural) and treatment of the rafiinate with concentrated sulfuric acid or oleum. Combinations of these treatments may be used and they are usually followed by a finishing treatment with a solid adsorbent, such as clay.
• the oils thus obtained may also be mixed with a small amount of an extract obtained by selective extraction after this has also been treated with concentrated sulfuric acid or oleum. In this connection reference may be made to British specifications 589,149 and 589,150.
• Desulfurization by selective hydrogenation is a refining method which is cheap and wherein only small amounts of the oil are lost. It has already been proposed to apply this refining method in the preparation of electrical insulating oils. From Brennstofichemie, 36, 218 (1955), it is known to prepare an electrical insulating oil by first removing the sulfur completely from a shale oil by hydrogenation and then treating the hydrogenated oil with sulfuric acid and bleaching earth.
• selective hydrodesulfurization is here meant a hydrogenation under conditions in which the non-hydrocarbons present in the oil (viz. the compounds which in addition to carbon and hydrogen contain other elements, such as sulfur or oxygen) are hydrogenated, but the hy drocarbons remain essentially unaffected (so that, for example, there is virtually no cracking of the oil or hydrogenation of aromatics present in the oil).
• non-hydrocarbons present in the oil viz. the compounds which in addition to carbon and hydrogen contain other elements, such as sulfur or oxygen
• the hy drocarbons remain essentially unaffected (so that, for example, there is virtually no cracking of the oil or hydrogenation of aromatics present in the oil).
• the oil may be in either the gas or the liquid phase during the hydrogenation, a very suitable method being trickle phase hydrogenation, wherein a very thin layer of the oil is allowed to flow over a bed of a catalyst.
• the selective hydrogenation is carried out at a temperature of 300-400 C., a pressure of 10-200 kg. per sq. cm., a gas discharge rate of 50- 5,000 liters per kg. of oil and a flow rate of the oil of 0.3-3 kg. per liter of catalyst per hour.
• Suitable catalysts are oxygen or sulfur containing compounds such as oxides and sulfides of metals of groups VI and VIII of the periodic table. Especially preferred are cobalt oxide, molybdenum oxide, ,tungsten sulfide and nickel sulfide.
• the catalysts are preferably such compounds supported on a carrier, such as active carbon, fullers earth, kieselguhr, silica or alumina, e.g.
• catalysts in the form of bauxite, pumice or burnt clay.
• Very suitable catalysts are described in British specification 657,400 and of these the catalysts comprising cobalt oxide and molybdenum oxide on an aluminum oxide-containing carrier, such as bauxite, are particularly preferred.
• lysts which contain cobalt and molybdenum in an ato mic ratio between about 0.7 and 0.8, are particularly eifective.
• the catalysts may be used in the form of cylindrical tablets measuring, for example, 5 x 5 or 3 x 3 mm.
• the selective hydrodesulfurization should be carried out so that, the oil is not completely desulfurized.
• the hydrogenated oil should still contain at least 0.05% by; weight of sulfur and in most cases not more than of the sulfur originally present in the oil should be removed.
• the sulfur content of thehydrogenated oil should not be too high and should genunexpectedly to the stability of the insulating oils is not fully understood.
• the sulfur compounds remaining in v. the oil after the hydrotreating step are, of course, more Patented July 17, 1962 i hydrogenation resistant and of different average composition and configuration than those which are removed.
• an oil When desulfurized to the extent indicated above, an oil will be obtained which satisfies at least one of these specifications and can, therefore, be considered to be suitable for use as an electrical insulating oil.
• Hydrogenation to a sulfur content of OAS-0.35% by weight (still more preferably .200.30% by weight) is very suitable, since then from various starting materials an insulating oil can be obtained which satisfies more than one specification at the same time, which is of advantage to the manufacturer from the point of view of economy of production.
• hydrogen sulfide is formed from the sulfur compounds present in the oil.
• a part of the hydrogen sulfide formed dissolves in the oil, and this should be removed from the oil. This can be effected, for example, by washing the oil with a caustic alkali solution, but it is most simply carried out by blowing through the oil an inert gas such as nitrogen, if desired, at elevated temperature or by stripping with steam.
• the oil is treated with a solid adsorbent such as fullers earths and activated clays.
• Suitable adsorbents are, for example, fullers earths of the attapulgite and montmorillonitic types and acid activated clays such as bentonite, bauxite, and alumina.
• Small quantities of alkaline material such as lime may be added to the adsorbent.
• the oil may be heated during the treatment (for example, to a temperature of about 50-100 C.), and an inert gas such as nitrogen passed through the oil.
• the quantity of adsorbent used generally lies between 0.5 and 30% by weight, preferably between 1 and 5% by weight, calculated on the oil treated.
• the process of the invention is generally applicable to mineral oil fractions having a viscosity between about 1 and 9 degrees Engler at 20 C., i.e. light lubricating oil distillates, such as spindle oils. In most cases a distillate boiling in the range of from 300 to 500 C. is used as the starting material. Of course, the starting material should be so selected, that after desulfurization to the prescribed extent the desired sulfur content can be attained.
• the process of the invention is of particular advantage for starting materials having a relatively high sulfur content, ie oils having a sulfur content of at least 1% by weight, and particularly those having a sulfur content of at least 1.5% by weight.
• the desired light lubricating oil distillate It is not necessary to separate first the desired light lubricating oil distillate from a mineral oil and then to hydrogenate the separated distillate and to treat it with a solid adsorbent. It is also possible to start from a fraction which in addition to the desired light lubricating oil contains heavier components, such as heavier lubricating oils, and/ or lighter components, such as gasoline, kerosene or gas oil. Such a fraction may be selectively hydrogenated and the desired light lubricating oil separated from it after the hydrogenation by distillation. In this distillation the flash point of the separated light lubricating oil distillate fraction may be adjusted at the same time to the desired value.
• a high aromatic content of an electrical insulating oil has a favorable effect on its gassing characteristics, so that the process of the invention provides an excellent means for preparing insulating oils with good characteristics. This becomes particularly apparent when starting materials having a relatively high aromatic content are used, e.g. oils having an aromatic content of at least 30% by weight and particularly those having an aromatic content of at least 40% by weight.
• the oil was stripped with steam in order to remove the hydrogen sulfide and the lightest components. Approximately 8% by weight of the oil was removed during this treatment. The remaining oil had a flash point of 148 C., a sulfur content of 0.25% by weight and an aromatic content of 45% by weight.
• the oxidation stability of the final oil was determined in the B.S.I. test (B.S. 148/1951). According to the content of 0.48% by weight.
• the gassing characteristics of the final oil were evaluated in the modified Pirelli apparatus (Journal of the Institute of Petroleum, 35, No. 311, pp. 735-754) at a temperature of 50 C. under a hydrogen atmosphere and a voltage of 10 kv.
• the amount of hydrogen is measured which the oil absorbs or evolves under these conditions in the course of time.
• the hydrogen absorption or hydrogen evolution expressed in mm. of oil pressure is plotted in a graph as a function of the time and the slope of the line thus obtained determines the gassing coefficient of the oil. For the present oil this coefficient was found to have the very favorable value of 8, which means that the oil is very strongly gas absorbing.
• Run B The procedure of Run A was repeated, except that the Filtrol treatment of the oil was omitted. In the 13.8.1. test the oil had a sludge value of 2.4% by Weight and an acid number of 2.0.
• Run C The same starting material used in Run A was bydrogenated and stripped with steam as described for Run A. Then the oil was treated with 2% by weight of 96% sulfuric acid for /2 hour at a temperature of '20" C. The acid sludge was then allowed to deposit and was separated 011?. Finally the oil was treated with 3% by weight of Filtrol, to which 0.2% by Weight of lime had been added (the percentages are calculated on the quantity of oil treated), at 75 C. for A2 hour while nitrogen was passed through it. In the B.S.I. test the final oil had a sludge value of 1.63% by weight and an acid number of 1.3.
• Run D An electrical insulating oil satisfying the E81. test was prepared by a conventional method from the same starting material as was used in Run A.
• the raflinate thus obtained was treated with 10% by weight of oleum (containing 17% by weight of dissolved S for /2 hour at a temperature of 20 C.
• the acid sludge was then allowed to deposit and was separated off.
• the oil was washed with a 4% solution of NaOH in 40% aqueous alcohol and subsequently with dilute alcohol and water.
• Finally the oil was treated at 75 C. with 3% by weight of Filtrol for /2 hour while nitrogen was passed through it.
• the yield of final electrical insulating oil was 55% by weight.
• the oil had a sludge value of 0.84% by weight and an acid number of 1.4.
• the gassing coeificient of the oil was positive.
• oils of type A can be improved by the addition of mineral oil fractions having a lower aromatic c'on- B. It is clear that this possibility is particularly of im-' portance for oils of type A having a high aromatic content.
• the sulfur content of the oil of type B should not be such that the sulfur content of the final mixture becomes unduly high. Generally the sulfur content of the final mixture should not be above 0.6% by weight.
• the oil of type B is preferably obtained from the same starting material as the oil of type A to result in an espe cially suitable electrical insulating oil in accordance with the invention.
• Oils of type B may be obtained by extracting an oil in a known manner with a selective solvent for the aromatic components of the oil, e.g. liquid sulfur dioxide or furfural.
• the oil of type B may also be subjected to other refining treatments, such as treatment with concentrated sulfuric 'acid or oleum or selective hydrogenation.
• the oil of type B is also subjected to a finishing treatment with a solid adsorbent. This finishing treatment may be carried out in the same way as described above in connection with the preparation of the oil of type A.
• the finishing treatment may be carried out either on the oils of type A and B separately, or after blending.
• this treatment may be carried out in any known manner.
• concentrated sulfuric acid (80100%) or oleum (up to 30% by weight dissolved S0 may be used in amounts of from 5-30% by weight, calculated on the oil treated, as temperatures varying from 0 to C. and contact times from 5 sec. to one hour.
• the extraction can be carried out in one or more stages and either batch- Wise or continuously. In batchwise refining the treatment temperature is preferably approximately 25 C., and in continuous refining preferably approximately 60 C. After the extraction with concentrated sulfuric acid or oleum, the acid sludge is removed from the oil.
• the oil may then be neutralized by treatment with an alkaline material, such as an aqueous or alcoholic solution of NaOH, which may be fol-lowed by washing with water and/ or alcohol.
• an alkaline material such as lime, may be added to the solid adsorbent with which the oil is finished.
• the oil of type B is prepared by extracting an oil With a selec tive solvent for the aromatic components of the oil fol-' lowed by subjecting the rafiinate thus obtained to a treat ment with concentrated sulfuric acid or oleum and a finish ing treatment with a solid adsorbent. This is illustrated by the following example.
• EXAMPLE II An oil of type B was prepared from a portion of the same starting material as used in Example I. This portion of the starting material was extracted with liquid sulfur dioxide, so as to obtain a rafiinate having an aromatic content of 9% by weight. This rafiinate was treated with oleum, neutralized and finished with Filtrol as in Run D of Example I.
• an insulating oil may be prepared as follows. The starting material is selectively hydrogenated and the hydrogenated oil is divided into two parts. One part is treated with a solid adsorbent so as to obtain an oil of type A. The other part is extracted with a solvent selective to aromatics and the raffinate thus obtained is treated with a solid adsorbent so as to obtain an oil of type B. Finally the oils of type A and B are mixed.
• the two oils may also be mixed before being treated with a solid adsorbent and the mixture treated with a solid adsorbent.
• a proportion of at least but not more than about 60% by weight of the hydrogenated oil is extracted.
• the conditions of extraction are preferably such as to give a raffinate yield of at least 70% by weight of the extracted portion of the hydrogenated oil.
• the degree of extraction of a 60% proportion of hydrogenated oil would thus be about 18% of the whole hydrogenated oil.
• the raffinate and unextracted hydrogenated oil after blending therefore comprises at least 80% by weight of the original hydrogenated oil.
• Example III The same starting material as was used in Example I was selectively hydrogenated and steam stripped as described in Example I. Several portions of the hydrogenated oil thus obtained were extracted with liquid sulfur dioxide under the conditions mentioned in the following table.
• the rafiinates thus obtained were mixed in varying proportions with the unextracted hydrogenated oil and the mixtures were finished by treatment with Filtrol as described in Example I.
• the blending proportions as well as the B.S.I. test results of the finished electrical insulating oils are given in the following table.
• Ratlinate 13.5.1 test Unextracted hydrogenated oil, amount, percent wt. Amount, Sludge, Acid percent Number percent valu0,mg.
• insulating oils prepared according to the invention may be added to the insulating oils prepared according to the invention.
• alkyl phenols such as 2,6-di-tert.butyl-4-methyl phenol, are particularly suitable.
• the insulating oils of the invention usually have a good inhibitor susceptibility.
• a process for the production of an oxidation stable non-gassing insulating oil from a sulfur-containing mineral lubricating oil mixture which also contains aromatics and boils within the range from about 300 to about 500 C. consisting essentially of the steps of (l) selectively hydrodesulfurizing said mixture without appreciable conversion of hydrocarbons therein to reduce the sulfur content by at least but by not more than about by weight, (2) separating from the hydrodesulfurized mixture by means of fractional distillation a light lubrieating oil fraction boiling from about 300 to about 500 C. having a viscosity at 20 C.

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• Chemical & Material Sciences (AREA)
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• Spectroscopy & Molecular Physics (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Organic Insulating Materials (AREA)

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  • NL NL280336D patent/NL280336A/xx unknown
• 1958
  • 1958-06-03 GB GB17714/58A patent/GB856887A/en not_active Expired
• 1959
  • 1959-05-27 US US816073A patent/US3044955A/en not_active Expired - Lifetime
  • 1959-06-02 JP JP1749259A patent/JPS3618584B1/ja active Pending
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