Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L10/00—Use of additives to fuels or fires for particular purposes
  • C10L10/14—Use of additives to fuels or fires for particular purposes for improving low temperature properties
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/192—Macromolecular compounds
  • C10L1/195—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C10L1/197—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and an acyloxy group of a saturated carboxylic or carbonic acid
  • C10L1/1973—Macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds derived from monomers containing a carbon-to-carbon unsaturated bond and an acyloxy group of a saturated carboxylic or carbonic acid mono-carboxylic

Definitions

• Mineral oils containing paraffin wax have the characteristic of becoming less fluid as the temperature of the oil decreases. This loss of fluidity is due to the crystallization of the wax into plate-like crystals which eventually form a spongy mass entrapping the oil therein.
• compositions act as wax crystal modifiers when blended with waxy mineral oils. These compositions modify the size and shape of wax crystals and reduce the adhesive forces between the wax and oil in such a manner as to permit the oil to remain fluid at a lower temperature.
• United Kingdom Patent 1263152 suggests that the size of the wax crystals may be controlled by using a copolymer having a lower degree of side chain branching.
• Typical sharply fractionated fuels have a 90% to final boiling point of 10 to 20°C usually with a 20 to 90% boiling range of 90 to 110°C. Both types of fuel have final boiling points above 350°C generally a final boiling point in the range 350°C to 375°C especially 350°C to 370°C.
• copolymers of ethylene and vinyl acetate which have found widespread use for improving the flow of the previously widely available distillate fuels generally contained up to about 30 wt % vinyl acetate where the additive was used to control the size of wax crystals forming in the fuel or they contained around 36 wt % or more vinyl acetate where their prime function was to lower the pour point of the distillate fuel. We have not found either of these types of additive to be effective in the treatment of the narrow boiling and/or sharply fractionated fuels described above.
• copolymers of ethylene and vinyl esters of carboxylic acids containing from 1 to 4 carbon atoms containing from 32 to 35 wt % of the vinyl ester and having a number average molecular weight of from 1000 to 6000 are particularly effective in the treatment of these of fuels.
• the present invention therefore provides the use as an additive for improving the flow properties of a distillate petroleum fuel oil whose 20% and 90% distillation points differ within the range of from 65 to 100°C, and/or for improving the flow properties of a distillate fuel whose 90% to final boiling point is 10 to 20°C of an additive comprising a copolymer of ethylene and a vinyl ester of a carboxylic acid containing 1 to 4 carbon atoms containing 32 to 35 wt % of the vinyl ester and having a number average molecular weight of 1000 to 6000.
• the present invention further provides a distillate fuel whose 20% and 90% distillation point differ by 65 to 100°C and whose 90% boiling temperature is from 10 to 30°C of the final boiling point and/or whose 90% to final boiling point is 10 to 20°C and containing from 50 to 500 ppm (parts per million) of a copolymer of ethylene and a vinyl ester of a carboxylic acid containing 1 to 4 carbon atoms containing 32 to 35 wt % of the vinyl ester and having a number average molecular weight of 1000 to 6000.
• the copolymer of the ethylene and vinyl ester of the carboxylic acid may be a mixture of two copolymers such as those generally described in United States Patent 3,961,916 which may or may not contain the same vinyl ester.
• an additive combination containing at least 10 parts by weight of the growth arrestor for each part by weight of the wax crystal nucleator is suitable for treating this type of fuel.
• the mixture being particularly useful since it allows added flexibility.
• a preferred embodiment of the present invention therefore provides the use as an additive for improving the flow properties of a distillate petroleum fuel oil whose 20% to 90% distillation points differ within the range of from 65 to 100°C, and/or of a distillate fuel whose 90% boiling temperature is from 10 to 30°C preferably 10 to 20°C of the final boiling point an additive comprising from 10 to 15 parts by weight of a synthetic polymeric material having the property of a wax growth arrestor in said fuel for each part of a synthetic polymeric material having the properties of a wax growth stimulator, said wax growth arrestor and growth stimulator being copolymers of ethylene and vinyl esters of carboxylic acids containing from 1 to 4 carbon atoms the average ester content of said copolymers being in the range 32 to 35 wt.% and the number average molecular weight thereof being in the range 1000 to 6000.
• the present invention provides a distillate fuel whose 20% to 90% boiling fraction differ in their boiling point by from 65 to 100°C and/or a distillate fuel whose 90% to final boiling point is 10 to 20°C containing from 50 to 500 ppm parts per million of an additive mixture of 10 to 15 parts by weight of a synthetic polymeric material having the property of a wax growth arrestor in said fuel for each part of a synthetic polymeric material having the properties of a wax growth stimulator said growth arrestor and growth stimulator being copolymers of ethylene and vinyl esters of carboxylic acids containing from 1 to 4 carbon atoms, the average ester content of said copolymers being in the range 32 to 35 wt.% and the number average molecular weight thereof being in the range 1000 to 6000.
• the fuels whose 20% to 90% distillation points differ within the range 65 to 100°C their 90% boiling temperature generally is from 10 to 30°C of the final boiling points generally have a final boiling point above 350°C usually between 350°C and 375°C more usually between 350°C and 370°C.
• the fuels whose 90% to final boiling point is 10° to 20°C usually have a 20 to 90% distillation range of from 90° to 110°C and also generally have final boiling points above 350°C usually between 350°C and 375°C more usually between 350°C and 370°C.
• the wax growth stimulator or nucleator is a synthetic polymeric material which is soluble in the distillate at temperatures substantially above the saturation temperature but on cooling of the distillate progressively separates out in the form of small particles as the temperature of the distillate approaches the saturation point, e.g. is cooled from a point slightly above (e.g. 10°C above; preferably about 5°C above) said saturation temperature.
• saturation temperature is defined as the lowest temperature at which solute, e.g. wax, cannot be crystallized out of the solution even if known crystallization inducement methods are used. Whilst not known certainly it is believed that as cooling continues, additional nucleator particles separate out in a more or less continuous manner.
• additional particles act as nucleators for continued wax crystallization, which in effect, would prevent substantial supercooling of the distillate.
• the advantages of having fresh nucleator particles formed continuously is that the supersaturation of the distillate with n-paraffins is kept at the lowest possible level thus facilitating a molecule of growth arrestor to build itself into the growth center of growing crystals and by so doing to stop the further growth.
• the inhibitory effect of a growth arrester is believed to result from the presence of bulky groups in its molecule. Additional nucleator should separate out to replace the deactivated growth centers.
• the wax growth arrester is more soluble in said distillate than said nucleator and it acts as a growth arrester as the wax crystal forms.
• the nucleator should not be insoluble in the distillate at elevated temperatures nor should it start to separate out at a temperature substantially above that at which wax crystallization can occur. If nucleators separate out at a temperature substantially above the temperature at which crystallization can occur, then they tend to settle at the bottom of the vessel holding the distillate, instead of remaining dispersed within the distillate. This factor is especially important when the distillate is subjected to repeated warming and cooling as during tne warm and cool parts of a day since it does not result in adequate redispersion of the nucleant particles in the distillate.
• the synthetic polymeric materials used as wax growth stimulators and wax growth arresters may contain the same or different vinyl esters.
• wax crystal growth stimulators for the purpose of this invention, wax nucleators and nucleants for wax are all considered equivalent terms and are used interchangeably.
• W ax growth arresters generally include in their molecular structure wax-like polymethylene segments which are capable of building themselves into the lattice of the wax crystals at the point of lattice dislocation, and also contain bulky groups which prevent incorporation of further molecules of n-paraffins at the point of lattice dislocation and by so doing stop further growth of crystal.
• a good synthetic polymeric wax nucleator can be chosen by visually comparing a transparent container containing a 0.1 to 3.0 wt.% solution of the potential nucleator in a distillate to an identical container with the same distillate having no additive, as the temperature of the two materials is lowered.
• the onset of the wax crystallization from the distillate containing a polymeric material which has nucleator characteristics will occur at a higher temperature than that at which the crystallization will start in the absence of said nucleator.
• a wax arrester usually is characterized by the ability to delay onset of crystallization.
• the synthetic polymers used as nucleating agents and as wax growth arresters are copolymers of ethylene and vinyl ester and may contain the same or different ester monomer.
• the vinyl ester content and molecular weight are the average over the mixture.
• the additive may however also be single polymer by which is meant material produced in a single polymerisation. In this instance the materials may be obtained by the well known high pressure or solution polymerisation techniques that have previously been suggested for the production of ethylene vinyl ester, especially vinyl acetate copolymers for fuel additives.
• Typical vinyl esters for both mixtures and single polymers include vinyl acetate, vinyl propionate, and vinyl butyrate.
• the molecular weight is the average of the two polymers and in general, the preferred number average molecular weight (VPO) for the nucleator will be within the range of 500-6000, more preferably 1200-6000.
• VPO number average molecular weight
• a relatively low molecular weight ethylene- vinyl ester copolymer with a relatively high vinyl ester content has been found to act as a wax growth arrester.
• a relatively high molecular weight copolymer of ethylene with a vinyl ester which copolymer has a relatively low content of vinyl ester acts as a nucleating agent.
• the nucleant is an ethylene/vinyl acetate copolymer its number average molecular weight is preferably at least 500, preferably 1000, higher and/or the ester content at least 5% lower than the corresponding property of the wax growth arrester.
• the nucleator can comprise an ethylene-vinyl acetate copolymer of a higher molecular weight if the vinyl acetate content of both polymeric materials is about equal.
• two synthetic polymers may be made separately or they can be made consecutively in one batch by varying the reaction conditions.
• the reaction conditions can be selected so that the initial polymerization reaction produces a polymer having primarily nucleator characteristics and the reaction conditions can be changed to produce a polymer having primarily wax growth arresting properties or vice versa. In this manner, a mixture of polymers can be produced having both types of functions.
• the relationships between the concentration of vinyl acetate in the copolymer and molecular weight of the copolymers are important since they are factors which determines the role of the particular copolymer in the fuel. That is, they determine, given the other polymer properties are similar whether or not the copolymer as a whole will be performing within the composition as a wax arrester or as a wax nucleating agent.
• the nucleating agents should have relatively long polymethylene segments, and so as these synthetic polymers approach low molecular weight ranges, the proportion of vinyl acetate should also decrease.
• the specific wax nucleating agents will comprise a copolymer of ethylene and a relatively low proportion of vinyl acetate with a relatively high molecular weight.
• the wax arrester on the other hand will, in general, be a relatively low molecular weight copolymer of a relatively high vinyl acetate content since the function of wax arresting depends more on the presence of bulky groups, such as ester groups, attached to the backbone of the molecule of the copolymer.
• both the preferred relatively lower molecular weight high vinyl acetate (second) copolymer and the preferred first , the relatively high molecular weight low vinyl acetate copolymer may be dissolved in a kerosene or heavy aromatic naphtha.
• Preferred concentrates will contain 5-60%, preferably 10-50% total copolymer with the balance being a hydrocarbon oil solvent.
• the arrester copolymers may be prepared by known procedures employing free-radical initiators, preferably organic peroxide compounds. Suitable procedures are high temperature and high pressure processes or the solution processes U.S. specifications, such as U.S. Pat. Nos. 3,048,479 or 3,093,623 and United Kingdom Patent Specification 1263152.
• the fuels to which the present invention relates are difficult to treat with conventional additives because of the relatively narrow boiling range of the 20% to 90% degree fraction of the fuel, the 90% fraction boiling from 65 to 100°C above that of the 20% fraction and/or because of the relatively small gap between the 90% boiling point and the final boiling point of less than 25°C and even, in some instances less than 20°C.
• the polymeric materials are used in ratios of 10 to 15 parts by weight of growth arrester, per part of the nucleator.
• additive A was an oil solution containing 63 wt.% of a combination of polymers comprising 13 parts by weight of a wax crystal growth arrestor comprising an ethylene vinyl acetate copolymer of number average molecular weight 2500 and vinyl acetate content of 36 wt.% and 1 part by weight of wax crystal simulator of number average molecular weight 3500 and a vinyl acetate content of about 13 wt.%
• Additive B was an oil solution containing 45 wt.% of an additive combination of 3 parts by weight of the abovementioned wax crystal growth arrestor and 1 part of the wax crystal simulator according to United States Patent 3961916.
• Additive C is 50 wt.% solution in oil of an ethylene acetate copolymer of number average molecular weight 2000 and vinyl acetate content 30 wt.%.
• the fuels used in the Examples were as follows:
• the Wax Crystal Size at Fast Cooling Rates is measured by the Cold Filter Plugging Point test (CFPP).
• CFPP Cold Filter Plugging Point test
• This test is carried out by the procedure described in "Journal of the Institute of Petroleum", Volume 52, No. 510, June 1966, pp. 173-185.
• the.CFPP test is carried out with a 45 ml sample of the oil to be tested.
• the oil placed in the ASTM cloud point jar is cooled in a bath maintained at about -30°F. Every two degrees drop in temperature, starting from 4°F.
• the oil is forced at a suction of 8 inches of water through a filter element provided with a 350 mesh screen into a pipette to a mark indicating a volume of 20 ml., at which time the oil is allowed to return by gravity flow to the cooling chamber.
• the test is repeated with each 2°C drop in oil temperature until the oil fails to fill the pipette in a period of 60 seconds to the aforesaid mark.
• the results of the test are reported as the Cold Filter Plugging Point which is the highest temperature at which the oil fails to fill the pipette.
• the fuels used were: and the additives used were A, B and C as used in the previous example together with Additives D to H as follows:

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• 1983
  • 1983-01-04 GB GB838300016A patent/GB8300016D0/en active Pending
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• 1984
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• 1992
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