CA1103913A

CA1103913A - Insulating oil

Info

Publication number: CA1103913A
Application number: CA283,197A
Authority: CA
Inventors: Jerry Ourlian
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1976-08-24
Filing date: 1977-07-20
Publication date: 1981-06-30
Also published as: NL7709350A; DE2734227A1; FR2362919A1; IT1085013B; BE857478A; JPS5335200A; GB1582212A

Abstract

ABSTRACT OF THE DISCLOSURE
An excellent insulating oil for use in transformers and the like is manufactured from a decanted oil from the catalytic cracking operation in a refinery by extraction, fractionation and dewaxing said decanted oil.

Description

INSULATING OIL

This invention relates to a novel insulating oil and more particularly pertains to paraffinic insulating oils for use in electrical transformers, switch gears and the like, and to a process for their manufacture.
Insulating oils for transformers, switch gears and the like are commonly acid- or hydrogen finished naphthenic oils which provide cooling and the proper dielectric properties under various conditions of use.
Naphthenic oils are now in short supply and somewhat expensivet and it has become important to find substitutes for these types of insulating oils which have all of the requisite properties. Highly refined viscous petroleum oils possess unusually good oxidation sta~ility. These oils possess oxidation stability which surpasses the require-ments for transformer oil. However, many of these oils tend to absorb oxygen when heated, particularly in the ,~
presence of metals such as copper, causing undesirable ~; formation of acids in the oil. Such oils, therefore, ;~; 20 are unsuitable for use as transformer oils.
~' Naphthenic oils which traditionally have been used as transf~rmer oils in the past have been obtained from erude oils from wells located in the Gulf Coast region of the United States. Many of these wells are old wells and no longer of economic importance. The long ~; term outlook for naphthenic oils is thus for a decreased supply and rising cost.

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Heretofore, paraffinic-based oils per se have been excluded as candidates for insulating oils because of their poor low-temperature performance and their marginal resistance to oxidation under use conditions.
Previous practice in transformer oils has been to formulate paraffinic oils with naphthenic base oils (see U.S. Patent No. 3,095,366, for instance) because the paraffinic oils did not have the necessary dielectric, low temperature, and oxidation resistance required for this application.
- I have now discovered an insulating oil formulation based on a paraffinic oil which is in good supply from petroleum refineries which paraffinic oil is derived from the decanted oil stream resulting from the catalytic cracking operation in a petroleum oil refinery.
This decanted oil stream is purified for the purpose ; of this invention by subjecting it to extraction, e.e.
with furfural, to remove aromatic hydrocarbons and yield a raffinate. This raffinate is then fractionated and dewaxed to yield a low viscosity base oil of about . ~ :
60 saybolt viscosity at 100F. and pour point 0F. This ; base oil is then subjected to clay contacting at 225F.
for about 15 minutes using attapulgite at a treating level of about 10 pounds of clay per barrel of oil. It is also preferred that a small amount of a filter aid such as ; diatomaceous earth (1-2 pounds per barrel of oil~ be added in the clay contacting to improve the moisture removal from the oil and to improve the filterability through the filter cake.

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This clay treatment is believed to improve the dielectric strength and interfacial tension and it reduces the moisture level of the oil. Transformer oils, for instance, are required to have good low-temperature service life. Thus, the oil of this invention is usually compounded with a pour depressant. We have found that Exxon PDX 149 (which i8 a complex condensation produc~ of paraffin wax and naphthalene which is prepared by chlorinating paraffin wax and condensing the chlorinated product with naphthalene by the Friedel-Crafts reaction) in the range of from 0.25 to 0.5% by weight will depress the pour point of our oil to -35 F.
without adver6ely affecting the other required performance parameter~. In addition, $t is preferred to add to our insulating oil a metal suppressant to control the catalytic affect of source copper which is normally found in electri- -cal systems. Typical levels of pour depressant in the oil is about 0.25~ by weight and for the metal suppressant is about 0.10~ by weight.
Thus, in accordance with the present teaching~, an insulating oil formulation i8 provided which has excellent oxidation stability and consists essentially of a solvent refined and dewaxed catalytic cracker decanted oil boiling within the range of about 590 P. to 700 F. and which ha6 a viscosity at 100 F. of about 35 ssu, a fla~h point of 325F. and a pour point of -5F. and from 0.25 to 0.5% based on the . . .
weight sf oil of complex condensation product of paraffin wax and naphthalene which i8 prepared by chlorinating paraffin wax and conden~ing the chlorinated :, . ..
'r~ ~ ~ product with naphthalene by the ~riedel-Crafts reaction.
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In the following exsmple, which will further illustrate the pre~ent !~ invention, the am:ounts of ingredient~ are expressed in parts by weight unless otherwi~e lndicated.

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' EXA~PLE
,, The oils useful in my invention as transformer oil6 are prepared fr~m the ~o-called ~decanted oils" which are obtained from the catalytic crac~ing operation~. In the catalytic operations, the total cracked : , .

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, 3~3 products are removed from a cracking zone and are conducted 1o a product fractionator. This fractionating is done to separate the cracked products into materials of different boiling ranges. The bottom product obtained from the fractionator will always contain a small percentage of catalyst particles which are carried over from the cracking zone. It is usually desirable to remove these catalyst particles before the oil can be subjected to further treatment, and the removal of the catalyst particles can be conveniently accomplished in a decanting zone wherein the catalyst particles are permitted to separate from the oil by means of gravity, hence the term decanted oil. Decanted oil usually comprises that fraction of the cracked products boiling in the range of about 500-1100~.
In order to render the decanted oil suitable for use as a transformer oil, it is necessary to subject the oil to conventional refining techniques including solvent extraction and dewaxing. In the instant case, furfural extraction followed by MDU dewaxing to about 0F. pour point of decanted oil yields an oil (HVI 70) having a viscosity of 70 saybolt seconds at 100F. This oil is then fractionally distilled to yield an overhead fraction (HVI 55) having a viscosity of 55 saybolt seconds at 100F. This H~I 55 oil which is embodied in my invention has the following boiling characteristics:

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- . . -50% 679F
end point 754F
The HVI 55 oil described above was then clay contacted with an activated attapulgite clay using a dosage of 10 pounds of clay per barrel of HVI 55. In the clay-contacting treatment, the oil was heated to 225F., the clay was added and the mixture was agitated for 15 minutes. The clay was then removed by filtration using a small amount of diatomaceous earth as filter aid.
The resulting oil was then treated with 0.25% by weight of Paraflow PDX ~ 149 for proper pour-point depres-sion.
Although the foregoing blend of HVI 55 and Paraflow is ordinarily sufficient for a final transformer oil formulation, if the formulation should not fully meet the ASTM 1275 corrosion specification, it is .
preferred to add to the formulation about 0.10% by weight of DuPont DMS~ (an alkyl acid salt of a complex organic ~ amine) and about 0.07% by weight of dibutyl paracresol fo~ improved storage stability.
The folIowing is a typical non-naphthenic transformer oil (HVI 55) formulation in accordance with the present lnvention:
HVI 55 Balance PDX 149 0.25 - 0.50% by weight alkyl acid salt ; o~ a complex ~ organic amine 0 - 0.15% by weight ; ~ 30 dibutyl paracresol 0 - 0.08% by weight ' ~

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., 1~LP3~3 The non-naphthenic oil HVI 55 has the following typi-cal inspections:
gravity, API 34.5 specific gravity 0.8628 pounds per gallon 7.184 pour, F -5 flash, F 325 color viscosity @210F., cst 2~45 viscosity @210F., sus 34.4 viscosity @100F., cst 9.33 viscosity @100F., sus 34.4 viscosity index 92.5 gravity constant 0.833 refractive index @20C. - 68F. 1.4558 refractive index @70C. - 158F. 1.4549 carbon residue, ramsbottom, ` ~ by weight 0.057 ~i :
ASH, % by weight 0.00 copper corrosion ASTM D130 3 hrs. @.100F. lA
24 hrs. @ 100F. lA
: 3 hrs. @ 210F. lA
24 hrs. @ 210F. lB
Molecular Weight 282 : Distil~lation Range %:Recovered ASTM
IBP 595F.
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2~ 617 ~ . :

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:~L~3~L3 . ~4942) % Reco~ered A~3TM

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6~38 71~

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Claims

(4942) I CLAIM:

1. An insulating oil formulation having excellent oxidation stability consisting essentially of a solvent refined and dewaxed catalytic cracker decanted oil boiling within the range of about 590°F. to 700°F. and having a viscosity at 100°F. of about 35 ssu, a flash point of 325°F. and a pour point or -5°F. and from 0.25 to 0.5% by weight based on the weight of oil of a complex condensation product or paraffin wax and naphthalene which is prepared by chlorinating paraffin wax and condensing the chlorinated product with naphthalene by the Friedel-Crafts reaction.

2. The formulation of claim 1 which contains from 0to 0.15% by weight or an alkyl acid salt of a complex organic amine.

3. me composition or claim 2 which contains from 0 to 0.08% by weight or dibutyl paracresol.