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
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11C—FATTY ACIDS FROM FATS, OILS OR WAXES; CANDLES; FATS, OILS OR FATTY ACIDS BY CHEMICAL MODIFICATION OF FATS, OILS, OR FATTY ACIDS OBTAINED THEREFROM
  • C11C3/00—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom
  • C11C3/14—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom by isomerisation

Definitions

• the present invention pertains to triglyceride-based dielectric fluids for electrical and/or power applications, methods for preparing said fluids, electrical and/or power apparatuses comprising said fluids, as well as uses of the dielectric fluids as such.
• Insulating, dielectric fluids are used in electrical apparatuses like transformers, capacitors, switchgear, bushings, etc., and have a multitude of functions.
• Dielectric fluids act as electrically insulating medium separating the high voltage and the grounded parts within the apparatus and function as a cooling medium to transfer the heat generated in the current-carrying conductors. Additionally, the fluids provide a medium to monitor the health of a transformer during operation.
• the insulating liquid should also comply with other necessary and desired requirements.
• the fluid should have a high efficiency, long life, and minimal environmental impact. Further, the fluid has to be compatible with the materials used in the electrical equipment and it should not constitute a hazard for the health and safety of personnel.
• insulating fluids should fulfill various physical, electrical, and chemical properties and all these properties are regulated through standards and specifications that stipulate the minimum requirements for each one of the important properties.
• the dielectric breakdown withstand voltage can be defined as the voltage required to obtain a flashover in the oil between two electrodes of specified shape and placed at a certain distance from each other.
• the standards specify the type of electrodes and the gap distances required for the tests.
• the breakdown withstand is essentially an indicator of the oil purity from water, conducting particles, organic acids, and other electrolytes.
• an insulating fluid for applications in power and/or electrical apparatuses is pour point, impregnation capability, blendability and water solubility/max water content.
• the fluid has to be inert with many different materials, be free of sulphur and halogens, possess high flash/fire points and should not release or absorb gasses.
• a negative gassing tendency is a desirable property for the prevention of partial discharge.
• petroleum-based oils have been used as the insulating fluid in oil-filled transformers mainly because of advantageous properties relating to low viscosity, low pour point, high dielectric strength, easy availability and low cost.
• the transformer industry has been undergoing several changes.
• ester-based fluids silicone fluid, chlorinated benzenes, perchloroethylene, polyalphaolefins etc.
• ester based fluids both synthetic and natural are excellent alternatives to mineral oil, primarily due to their high biodegradability (lower environmental risk) and high values of flash points and fire points (high fire safety factor).
• natural esters based on vegetable oils with the main constituent being triglycerides, are preferred due to their renewability.
• vegetable oils are not utilized to any greater extent for power and/or electrical applications, as a result of a number of disadvantageous chemical and/or physical properties.
• Biodegradable natural ester-based liquids have high pour point temperatures as compared to mineral oil, which can be considered as a major drawback if the electrical apparatuses comprising the fluid have to be operated in extremely cold environments, a problem that is especially pronounced at higher voltage ratings. Further, a low pour point can cause changes in the dielectric and/or other properties of the fluid and the solid insulation impregnated with this fluid. This in turn can force design changes in the transformer which can lead to an increase in the manufacturing costs. A very low value of pour point is therefore desired for the vegetable fluid.
• Oxidation behavior of the materials is an important parameter when it comes to insulation degradation in a transformer.
• the aging of pressboard insulation over time releases small amounts of oxygen into the oil, and therefore the oil has to withstand the oxidation-induced degradation.
• the inherent stability to oxidation is highly dependent on the compositions of fatty acids in the base oil. Ester oils which are composed only of saturates (only C-C bonds in its structure) are stable against oxidation.
• Specific heat in combination with thermal conductivity is also an important property of dielectric fluids.
• a higher specific heat will cause a lower rise in the temperature of the oil and a higher thermal conductivity will ensure that even if the speed of circulation of the oil is marginally slower than what it is in the case of mineral oil, the amount of heat conducted from the hot-spot regions in the transformer will be higher.
• a higher thermal conductivity can also result in an enhanced heat transfer at slightly higher temperatures because the viscosity of the ester fluid would be reduced at those temperatures.
• dielectric fluids preferably derived from renewable resources, having numerous desirable properties in terms of inter alia reduced viscosity, improved heat transfer properties, reduced pour point, improved oxidation stability, and biodegradability, allowing for improved thermal management and better impregnation of pressboard/paper insulation, increased personnel health and safety, facilitated clean-up and prolonged service life of power and/or electrical apparatuses.
• the present invention fulfils the above-identified needs, as it provides, inter alia, dielectric, triglyceride fluids, comprising various chemical modifications, displaying desirable properties in terms of inter alia reduced viscosity, improved heat transfer properties, reduced pour point, improved oxidation stability, and biodegradability, allowing for improved thermal management and better impregnation of pressboard/paper insulation, increased personnel health and safety, facilitated clean-up and prolonged service life of power and/or electrical apparatuses. Further, the present invention relates to processes and methods for preparing said dielectric, triglyceride fluids, as well as their uses in electrical and/or power apparatuses, in addition to electrical and/or power apparatuses per se comprising said dielectric, triglyceride fluids.
• the present invention relates to a dielectric, triglyceride fluid having a fatty acid composition of between approximately 10% and approximately 100% fatty acids having at least one carbon-carbon double bond.
• the dielectric triglyceride fluid is obtained by reacting said at least one carbon-carbon double bond with at least one conjugated diene, resulting in the formation of a modified triglyceride having increased triglyceride fluidity.
• the present invention pertains to a method for preparing a dielectric, triglyceride fluids.
• the method comprises the steps of providing a triglyceride composition having a fatty acid composition of between approximately 10% and approximately 100% fatty acids having at least one carbon-carbon double bond.
• the at least one carbon-carbon double bond is subsequently reacted with at least one conjugated diene, normally in the presence of a catalyst, resulting in the formation of said dielectric, triglyceride fluids in accordance with the present invention.
• a third aspect of the present invention relates to an electrical and/or power apparatus comprising the dielectric triglyceride fluid of the present invention.
• the dielectric fluid functions as an insulating medium, as a result of its superior properties in terms of oxidation stability, fluidity, insulation, permittivity, reduced pour point, reduced viscosity, etc.
• the present invention pertains to various uses of the dielectric triglyceride fluid in electrical apparatuses, and/or in apparatuses for power applications, and/or in components utilized in said apparatuses.
• Apparatuses of interest as per the present invention may for instance be transformers, capacitors, switchgear, bushings, etc., as well components and/or parts utilized in power or electrical applications.
• the present invention relates to the use of a chemically modified triglyceride in dielectric fluids, wherein said chemically modified triglyceride is obtainable by reacting at least one carbon-carbon double bond of a triglyceride fatty acid moiety with at least one conjugated diene
• the present invention pertains to dielectric, triglyceride fluids for various power and/or electrical applications, methods for preparing said fluids, electrical and/or power apparatuses and components comprising said fluids, as well as various uses of said fluids.
• fatty acids shall be understood to relate to any one of the three acyl moieties of a triglyceride, meaning that, for instance, in a triglyceride fluid having a fatty acid composition of approximately 40% fatty acids having one carbon-carbon double bond, approximately 40% of all the acyl moieties in the triglyceride fluid as a whole comprises one carbon-carbon double bond.
• triglyceride fluidity generally relates to the reciprocal of the triglyceride viscosity, i.e. in the context of the present invention it shall be understood to pertain to the dynamics and/or mobility of the triglyceride fatty acid chains.
• naturally derived shall be understood to pertain to natural fluids and/or oils derived from renewable resources, for instance natural and/or genetically modified (GMO) plant vegetable seeds and/or fat from various animal sources.
• Said fluids and/or oils are generally comprised of triglycerides, i.e. three fatty acids linked to a glycerol moiety.
• the fatty acids may be saturated or un-saturated, with the unsaturations being either conjugated and/or unconjugated. Conjugation may be introduced synthetically, enzymatically, or by using any other types of physical and/or chemical means, or it may be naturally occurring.
• vegetable fluids and/or oils may for instance be selected from the group comprising, but that is not limited to, peanut, rapeseed, castor, olive, corn, cotton, canola, soybean, sesame, linseed, safflower, grapeseed, palm, avocado, pumpkin kernel, macadamia nut, sunflower, and any combinations and/or mixtures thereof.
• fluids and/or oils may be obtained from essentially any organisms being a suitable fluid and/or oil source. Fluids and/or oils derived from animal sources may be selected from the group comprising beef tallow, fish oils, lard, and any combinations and/or mixtures thereof. Naturally, various combinations of the above fluids and/or oils may be utilized, irrespective of the source.
• the fatty acids comprised in the triglycerides may be of essentially any length, having essentially any number of unsaturations, either conjugated and/or unconjugated.
• Fatty acids may be for instance be selected from the group comprising, but that is not limited to, oleic acid, linoleic acid, ⁇ -linolenic acid, myristoleic acid, arachidonic acid, icosapentaenoic acid, palmitoleic acid, erucic acid, and docosahexaenoic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, vaccenic acid, gamma-linolenic acid, behenic acid, erucic acid, lignoceric acid, or any other fatty acids, suitably modified, if needed, in accordance with the requirements of the present invention.
• alkyl or "alkylene”, as used herein, is a (C 1 -C 50 )alkyl or (C 1 -C 50 )alkylene moiety, e.g. a (C 2 -C 30 )alkyl or (C 10 -C 40 )alkylene moiety and is intended to encompass also the alkyl or alkylene portion of any functional group, e.g. an alkoxy, alkylamino, or carboxypolyoxyalkylene group.
• any alkyl or alkylene group in accordance with the present invention may be branched or unbranched, and/or cyclic.
• alkyl includes the monoradical derived from a branched or unbranched and/or cyclic alkane.
• the present invention relates to a dielectric, triglyceride fluid having a fatty acid composition of between approximately 10% and approximately 100% fatty acids having at least one carbon-carbon double bond.
• the dielectric triglyceride fluid is obtained by reacting said at least one carbon-carbon double bond with at least one conjugated diene, resulting in the formation of a modified triglyceride having increased triglyceride fluidity.
• the reaction between fatty acids having at least one carbon-carbon double bond and the at least one conjugated diene may take place through a Diels-Alder reaction mechanism, or a radical mechanism, or through any other reaction mechanism, known and/or unknown.
• the reaction occurs through a Diels-Alder mechanism, the at least one conjugated diene acts as the diene whereas the at least one carbon-carbon double bond acts as the dienophile.
• the reaction between fatty acids having at least one carbon-carbon double bond and the at least one conjugated diene which essentially results in the introduction of steric hindrance between the fatty acyl chains, leads to increased triglyceride fluidity, i.e. increased dynamics and facilitated motion of the triglyceride fatty acyl chains.
• the at least one conjugated diene further comprises at least one second moiety that further increases triglyceride fluidity.
• the at least one second moiety may be a saturated or unsaturated, branched, linear and/or cyclic hydrocarbon, optionally substituted with at least one heteroatom.
• the at least one second moiety may be attached to any part of the conjugated diene and, in yet another embodiment, the at least one second moiety may for instance be selected from the group comprising inter alia branched or linear, and/or cyclic, (C 1 -C 50 )alkyl, (C 1 -C 50 )alkenyl, and (C 1 -C 50 )alkynyl, any hydrocarbyl, aromatic hydrocarbons comprising at least one aromatic ring structure, any combination of the above and all of the above optionally substituted with at least one heteroatom, selected from the group comprising inter alia nitrogen, oxygen, phosphorous, boron, silicone, etc, and optionally further comprising various functional groups and/or moieties such as carboxylic acids, carboxylates, amines, primary amines, secondary amines, tertiary amines, quaternary amines, amides, imines, imides, azides, azo, cyanates, isocyanides, iso
• the conjugated diene may for instance be selected from the group comprising, alkyl-, alkenyl-, and/or alkynyl-substituted cyclopentadiene.
• the dielectric triglyceride fluid may comprise inter alia a triglyceride exemplified in a non-limiting manner by the following structural formula (I), shown merely in a schematic, inexact manner for simplicity, as will be immediately recognized by a person skilled in the art: wherein, x, y, and z may be independently selected from integers of 0-50, each R 1 and R 2 may independently be selected from the group comprising saturated or unsaturated, branched, linear, and/or cyclic (C 0 -C 50 )alkyl, each R 3 , R 4 , R 5 , R 6 and R 7 may be independently selected from hydroxy, hydroxyalkyl, hydroxyalkoxy, hydroxyalkoxyalkyl, hydroxypolyoxyalkylene, alkoxy, alkoxyalkyl, polyoxyalkylene, carboxy, carboxyalkyl, carboxyalkoxy, carboxyalkoxyalkyl, carboxypolyoxyalkylene, alk
• the above structural formula may be varied, for instance in terms of inter alia the number and location of substituted cyclohexenes (e.g. on which fatty acid chain(s) the substituted cyclohexene(s) are located, the position along the fatty acid chain(s)), the number and locations of unsaturations of the fatty acid chains (e.g. the presence of conjugated or unconjugated unsaturation(s), whether the unsaturations are located on the ester side or on the alkyl side of the substituted cyclohexene(s)), and the length and the branching of the fatty acid chains (e.g.
• the at least one second moiety that further increases the triglyceride fluidity may correspond to R 3 , R 4 , R 5 , R 6 and/or R 7 , in accordance with structural formula (I) above.
• any pair of R 3 , R 4 , R 5 , R 6 and R 7 may form a second ring system on the cyclohexene ring, for instance may a norbornene moiety be generated from a reaction between cyclopentadiene and the fatty acid having at least one carbon-carbon double bond.
• the dielectric triglyceride fluid may further comprise less than approximately 20% saturated fatty acids, less than approximately 40% di-unsaturated fatty acids, less than approximately 20% tri-unsaturated fatty acids, and more than approximately 0% of other fatty acids, in order to endow the fluid with desirable properties in terms of oxidation stability, fluidity, insulation, permittivity, reduced pour point, reduced viscosity, etc.
• the dielectric triglyceride fluid may further comprise less than approximately 15% saturated fatty acids, or less than approximately 10% saturated fatty acids, or less than approximately 5% saturated fatty acids.
• the dielectric triglyceride fluid may further comprise less than approximately 30% di-unsaturated fatty acids, or less than approximately 20% di-unsaturated fatty acids, or less than approximately 10% di-unsaturated fatty acids.
• the dielectric triglyceride fluid may further comprise less than approximately 15% tri-unsaturated fatty acids, or less than approximately 10% tri-unsaturated fatty acids, less than approximately 5% tri-unsaturated fatty acids.
• the dielectric triglyceride fluid may further comprise more than approximately 5% of other fatty acids, or more than approximately 10% of other fatty acids, or more than approximately 15% of other fatty acids, or more than approximately 20% of other fatty acids.
• the triglycerides utilized for the aspects and/or embodiment of the present invention may be naturally derived, optionally comprising synthetic modifications. Employing naturally derived triglycerides enables development of dielectric, triglyceride fluids, in line with a preferred embodiment of the present invention, for power and/or electrical applications.
• the dielectric triglyceride fluids as per the present invention may exhibit reduced viscosity, improved insulation, reduced pour point, improved oxidation stability, permittivity, biodegradability, as well as other highly attractive properties, for instance resulting in improved personnel health and safety, negligible environmental impact, and facilitated and safer handling.
• the present invention relates to a naturally derived triglyceride comprising one, two, or three carbon-carbon double bonds.
• Said naturally derived triglyceride may preferably be reacted with cyclopentadiene or cyclopentadiene substituted with alkyl, alkenyl, and/or alkynyl, generating a chemically modified triglyceride having increased fluidity, implying improved properties in terms of inter alia reduced viscosity, improved insulation, reduced pour point, improved oxidation stability, permittivity, and biodegradability.
• the dielectric triglyceride fluid may have a permittivity value in the range between approximately 2.2 and approximately 4.5, in order to provide a dielectric triglyceride fluid with optimized properties.
• One aspect of the present invention pertains to a method for preparing a dielectric, triglyceride fluid.
• the method comprises the steps of providing a triglyceride composition having a fatty acid composition of between approximately 10% and approximately 100% fatty acids having at least one carbon-carbon double bond.
• the at least one carbon-carbon double bond is subsequently reacted with at least one conjugated diene, normally in the presence of a catalyst, resulting in the formation of the dielectric triglyceride fluids in accordance with the present invention.
• the method for preparing dielectric, triglyceride fluids enables facile and inexpensive production of fluids with highly desirable properties in terms of inter alia oxidation stability, fluidity, insulation, permittivity, reduced pour point, and reduced viscosity.
• the catalyst is a Lewis acid, i.e. any substance capable of accepting a pair of electrons.
• the Lewis acid may for instance be selected from the group comprising aluminium chloride, ethylaluminium dichloride, and/or ethylaluminium sesquichloride.
• the reaction step may be carried out at between approximately 100°C and 200°C, preferably approximately 160°C. In yet another embodiment, the reaction step may be carried out at between approximately 10 kbar and approximately 16 kbar, preferably approximately 13 kbar, during, in a further embodiment, between approximately 20 h and approximately 30 h, preferably approximately 24 h.
• One aspect of the present invention relates to an electrical and/or power apparatus comprising the dielectric triglyceride fluid of the present invention.
• the dielectric fluid functions as an insulating medium, as a result of its superior properties in terms of inter alia oxidation stability, fluidity, insulation, permittivity, reduced pour point, reduced viscosity, etc.
• Another aspect of the present invention pertains to various uses of the dielectric triglyceride fluid for instance in electrical apparatuses, and/or in apparatuses for power applications, or in components utilized in said apparatuses.
• Apparatuses of interest as per the present invention may for instance be transformers, capacitors, switchgear, bushings, etc., as well components and/or parts utilized in power or electrical applications.
• the dielectric fluid may be utilized in for instance paints and coatings, printing inks, lubricants, surfactants, or within the food and/or cosmetics industry.
• the present invention relates to the use of a chemically modified triglyceride in a dielectric fluid, wherein said chemically modified triglyceride is obtainable by reacting at least one carbon-carbon double bond of a triglyceride fatty acid moiety with at least one conjugated diene
• the at least one conjugated diene may optionally further comprise at least one second moiety that further increases triglyceride fluidity.
• the at least one second moiety may be a saturated or unsaturated, branched, linear and/or cyclic hydrocarbon, optionally substituted with at least one heteroatom.
• the at least one conjugated diene may be selected from the group comprising cyclopentadiene, cyclopentadiene substituted with alkyl, alkenyl, and/or alkynyl.
• Cyclopentadiene is added to a solution comprising triglycerides having a fatty acid composition of between approximately 10% and approximately 100% fatty acids having at least one carbon-carbon double bond.
• the cyclopentadiene is reacted with the carbon-carbon double bond in the presence of a Lewis acid catalyst, which most likely mediates a Diels-Alder reaction between the dieneophile (i.e. the carbon-carbon double bond) and the diene (i.e. the cyclopentadiene).
• Said reaction produces a modified triglyceride displaying improved properties in terms of increased fluidity, insulation, permittivity, reduced pour point, reduced viscosity, improved oxidation stability, etc.
• a (C 1 -C 30 )alkyl having two carbon-carbon double bonds in conjugated positions i.e. a conjugated diene
• a conjugated diene is added to a solution comprising triglycerides having a fatty acid composition of between approximately 40% and approximately 100% fatty acids comprising at least one carbon-carbon double bond.
• the conjugated diene may be reacted with the carbon-carbon double bond of the triglyceride in the presence of a Lewis acid catalyst, which most likely mediates a Diels-Alder reaction between the dieneophile (i.e. the carbon-carbon double bond present on the fatty acid moiety of the triglyceride) and the diene (i.e.

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• 2010
  • 2010-06-30 EP EP20100168004 patent/EP2402956B1/fr not_active Not-in-force
• 2011
  • 2011-06-29 WO PCT/EP2011/060912 patent/WO2012001044A1/fr active Application Filing

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