DD236940A5 - ADDITIVE CONCENTRATE FOR INTEGRATION IN PETROLEUM DISTILLATE FUELS - Google Patents

Abstract

The flow properties of a distillate petroleum fuel oil whose 20% and 90% distillation points differ within the range of from 65 to 100 DEG C, and/or whose 90% to final boiling point is 10 to 20 DEG C is improved by the inclusion 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.

Description

Field of application of the invention

The invention relates to an additive concentrate whose inclusion in distillate fuels whose 20% and 90% distillation points differ in the range of 65 to 100 ⁰ C and / or to improve the flow properties of a distillate fuel whose 90% is up to the final boiling point 10 to 2O ⁰ C, to lead.

Characteristic of the known technical solutions

Paraffin wax-containing mineral oils have the property of decreasing oil temperature to lose flowability. This fluidity loss is due to the crystallization of the wax into plate-like crystals, which optionally form a sponge-like mass enclosing the oil contained therein.

It has long been known that various compositions act as wax crystal modifiers when blended with waxy mineral oils. These compositions modify the size and shape of the wax crystals and reduce the adhesive forces between the wax and the oil in such a way as to maintain the ability of the oil to remain fluid even at a lower temperature.

Various pour point depressants have been previously described in the literature, and several of these products are in industrial use. For example, U.S. Patent No. 3,048,479 teaches the use of copolymers of ethylene and C3 to Cs vinyl esters - e.g. Vinyl acetate - as pour point depressants for fuels, in particular heating oils, diesel fuels and jet fuels. Likewise known are polymeric hydrocarbon pour point depressants based on ethylene and higher alpha olefins, e.g. B. propylene. U.S. Patent No. 3,961,916 teaches the use of a copolymer blend wherein one copolymer is a wax crystal nucleator and the other copolymer is a growth stopper to control the size of the wax crystals. Similarly, British Patent 1,263,152 suggests controlling the size of the wax crystals by employing a copolymer having a lower degree of side chain branching.

With the increasing diversity of distillate fuels, fuel types are included which can not be treated with the existing additives or which would require an economically unacceptably high additive use. One particular group of fuels that pose such problems is the group that has a relatively narrow boiling range. Fuels are often characterized by their initial boiling point, their final boiling point, and the interim temperatures at which certain volume percentages of the original fuel were distilled. Fuels whose 20% to 90% distillation point in the range of 65 to 100 ⁰ C and thereby specifically differs from 70 to 100 ⁰ C (ASTM D 86) and their 90% boiling temperature generally from 10 to 30 ⁰ C and especially from 10 to 25 ° Cdes final boiling point, have proven to be particularly difficult to treat, sometimes they remain completely unaffected by additives or else require very high levels of additive. All distillations referred to herein correspond to ASTM D86 distillations.

Moreover, with the rise in crude oil prices, it has become important for a refinery company to increase its distillate fuel production and optimize its operations in terms of what is known as sharp fractionation, which in turn results in distillate fuels which are difficult to treat with conventional additives or which require a level of treatment that is unacceptably high from an economic point of view. Typical sharply fractionated fuels typically have a 20 to 90% boiling range of 90 to 110 ⁰ C. have a 90% final boiling point 10 to 20 ⁰ C. Both types of fuel final boiling points above 350 ⁰ C and a final boiling point generally in the range of 350 to 375 ⁰ C and thereby specifically from 25O ⁰ C to 370 ⁰ C.

The copolymers of ethylene and vinyl acetate, which have found wide application in improving the flow properties of previously widely distributed distillate fuels, generally contained up to about 30% by weight of vinyl acetate, which additive was used to increase the size of the wax crystals forming in the fuel to control; or the said copolymers contained about 36% by weight or more of vinyl acetate, their primary function being to lower the pour point of the distillate fuel. In our investigations, none of these types of additives proved to be effective in the treatment of the above-described narrow-boiling and / or sharply fractionated fuels.

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Object of the invention

The aim of the invention is to provide a new additive concentrate, which improve the flow properties of a petroleum distillate fuel, of which 90% proportions to the final boiling point 10 to 20 ⁰ C.

Explanation of the essence of the invention

The invention has for its object to find a concentrate which gives as an additive to a petroleum distillate fuel, this improved properties.

In the present invention, copolymers of ethylene and carboxylic acid vinyl esters of 1 to 4 carbon atoms containing 32 to 35 mass% of vinyl ester and having an average molecular weight of 1,000 to 6,000 are particularly effective in treating these fuels.

The present invention therefore provides the use of an additive to improve the flow properties of a petroleum distillate fuel whose 20% and 90% distillation points differ in the range of 65 to 100 ⁰ C and / or to improve the flow properties of a distillate fuel, its 90% to the final boiling point 10 to 20 ⁰ C, wherein this additive is composed of a copolymer of ethylene and a carboxylic acid vinyl ester having 1 to 4 carbon atoms, which consists of 32 to 35 wt .-% of vinyl ester and has an average molecular weight of 1000 to 6000 ,

The present invention further provides a distillate fuel whose 20% and 90% distillation point differs from 65 to 100 ⁰ C and whose 90% boiling point of 10 to 3O ⁰ C of the final boiling point is removed and / or its 90% to the final boiling point 10 to 20 ⁰ C and is 50 to 500 ppm (parts per million) of a copolymer of ethylene and a carboxylic acid vinyl ester having 1 to 4 carbon atoms, which consists of 32 to 35 wt .-% of vinyl esters and an average molecular weight of 1,000 to 6,000 having.

The copolymer of ethylene and carboxylic acid vinyl ester may be a mixture of two copolymers, as generally described in US Pat. No. 3,961,916, which composition may or may not contain the same vinyl ester. Specifically, we find that an additive combination containing at least 10 wt. Parts of growth stopper for each wt. Fraction of wax crystal nucleator-containing additive combination is suitable for the treatment of this type of fuel. The mixture is particularly useful in that it allows additional flexibility.

A preferred embodiment of the present invention therefore provides the use of an additive to improve the flow properties of a petroleum distillate heating oil whose 20% to 90% distillation points differ in the range of 65 to 100 ⁰ C and / or a distillate fuel whose 90% boiling point of 10 to 30 ⁰ C - preferably 10 to 20 ⁰ C - from the final boiling point, wherein the additive is an additive consisting of 10 to 15 parts by mass of a synthetic polymer material having the property of a wax growth stopper in said fuel and said 10 to 15 parts by weight each account for a portion of a synthetic polymer material having the properties of a wax growth stimulator and wherein said wax growth stopper and the growth stimulator are copolymers of ethylene and carboxylic acid vinyl ester having 1 to 4 carbon atoms whose average ester content i m ranges from 32 to 35% by mass and whose average molecular weight is in the range of 1,000 to 6,000.

In a further embodiment, the present invention provides a distillate fuel whose 20% to 90% boiling fraction differs in their boiling point of 65 to 100 ⁰ C and / or a Destallatbrennstoff whose 90% to the final boiling point 10 to 20 ⁰ C and with a content of 50 to 500 ppm of an additive mixture of 10 to 15 parts by weight of a synthetic polymer material acting as wax growth stopper in said fuel per fraction of a synthetic polymer material acting as a wax growth stimulator, wherein said growth stopper. and said growth stimulator are copolymers of ethylene and carboxylic acid vinyl esters having from 1 to 4 carbon atoms, the average ester content of said copolymers being in the range of from 32 to 35% by mass and the average molecular weight of said copolymers being in the range of from 1 000 to 6000 lies.

The fuels whose 20% to 90% distillation points differ in the range of 65 to 100 ⁰ C and their 90% boiling temperature is generally 10 to 3O ⁰ C from the final boiling points, generally have a final boiling point above 350 ⁰ C, usually between 350 ° C and 375 ° C and in particular between 35O ⁰ C and 370 ⁰ C. The fuels whose 90% to the final boiling point 10 ⁰ C to 20 ⁰ C, usually have a 20 to 90% distillation range from 90 ⁰ C to 110 ⁰ C and also in the general end boiling above 35O ⁰ C and usually between 350 ⁰ C and 375 ⁰ C and in particular between 350 ° C and 370 ⁰ C.

When the additive is a mixture, the wax growth stimulator or nucleator is present as a synthetic polymer material which is soluble in the distillate at temperatures well above the saturation temperature, but which increasingly precipitates as the particles cool as the distillate cools the distillate temperature approaches the saturation point, ie, when the distillate is cooled down from a point slightly above (eg 10 ⁰ C above, preferably about 5 ° C above) the said saturation temperature. The term "saturation temperature" is defined as the lowest temperature at which the solute, eg, wax, can not be crystallized out of the solution, even if known crystallization induction processes are used. it is believed that as nucleation proceeds, additional nucleating particles are separated in a more or less continuous manner, and these additional particles act as nucleators for continued wax crystallization which would ultimately prevent significant undercooling of the distillate The formation of fresh nucleantype particles is to maintain supersaturation of the distillate with η-paraffins at the lowest possible level, thus facilitating the incorporation of a growth-stopper molecule into the growing center of growing crystals t and thus stop further growth.

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It is believed that the inhibitory effect of a growth arrestor is the result of the presence of bulky groups in its molecule. Additional nucleator may be shed to replace the deactivated growth centers. The wax growth stopper is more soluble in said distillate than said nucleator, thus acting as a growth stopper as the wax crystals form.

The nucleator should not be insoluble in the distillate at elevated temperatures, nor should it begin to precipitate at a temperature substantially above that at which crystallization of the wax can occur. If nucleators precipitate at a temperature substantially above the temperature at which crystallization may occur, they tend to settle on the bottom of the vessel containing the distillate instead of remaining dispersed in the distillate. This factor is particularly important when the distillate is subjected to repeated heating and cooling, such as during the warm and cool sections of a day, as this does not result in sufficient redispersing of the nucleated particles in the distillate. The synthetic polymer materials used as wax growth stimulators and wax growth stoppers may contain the same or different vinyl esters.

In the context of the present invention, the terms wax crystal growth stimulators, wax nucleators and nucleants for wax are considered to be equivalent terms and used interchangeably.

Wax growth stoppers (hereinafter also sometimes referred to as wax stopper) generally include wax-like polymethylene segments in their molecular structure, capable of incorporating into the lattice of wax crystals at the point of lattice dislocation, and containing bulky groups involving the incorporation of additional molecules of Prevent η-paraffins at the point of lattice dislocation and thus stop the further growth of crystals.

A well-suited polymeric wax nucleator may be selected by visual comparison of transparent containers, one containing 0.1 to 3.0 mass percent solution of the possible nucleator in one distillate, and the other - identical - container containing the same distillate without additive, after the temperature of the two materials has been reduced. The onset of wax crystallization from the distillate containing a polymeric material having nucleator properties will occur at a higher temperature than the onset of wax crystallization which occurs in the absence of said nucleator. Likewise, a wax stopper is usually characterized as being capable of retarding the onset of crystallization.

The synthetic polymers used as nucleating agents and wax growth stoppers are copolymers of ethylene and vinyl esters, which may contain the same or different ester monomers.

With the preferred additive, which is a mixture of polymers as described above, the vinyl ester content and molecular weight exceed the average of the mixture. However, the additive may also be a single polymer, by which is meant a material which is prepared in a single polymerization.

In this case, the materials of the well-known high pressure or solution polymerization techniques hitherto proposed for the production of ethylene vinyl esters - especially vinyl acetate copolymers for fuel additives - can be obtained.

Typical vinyl esters for both blends and single polymers include vinyl acetate, vinyl propionate and vinyl butyrate.

When incorporated into the distillate fuels, the fluidity improvers preferably prove to be effective in:

1. Obtain the liquid state of these fuels at the processing temperatures

2. stopping the growth of precipitated wax crystals when the oils are subjected to slower cooling, ie cooling from 0.2 ⁰ F to 2 ° F / h (0.09 ⁰ C to 0.9 ° C / h) - a cooling which typical of those cooling rates that are encountered when "bulk oil" is exposed to atmospheric cooling.

3. Stop the growth of precipitated wax crystals when the oils of rapid cooling, that is, a cooling rate of 10 ° Fbis100 ° F / h (3.8 ⁰ C to 38 ° C / h) exposed werden- cooling, typical of those Cooling rates that are encountered when relatively warm oil transfer lines enter and are suddenly exposed to low temperatures.

All three of the above criteria are desired to ensure that a fuel remains pumpable and filterable under the conditions of its distribution and use.

As already mentioned, when using polymer blends, the molecular weight is the average of the two polymers, with the preferred average molecular weight for the nucleator generally being in the range of 500 to 6,000, more preferably in the range of 1,200 to 6,000. Specifically, for example, an ethylene-vinyl ester copolymer having a relatively low molecular weight and having a relatively high vinyl ester content has been found to be an effective wax growth stopper. On the other hand, an ethylene-vinyl ester copolymer having a relatively high molecular weight and a relatively low vinyl ester content acts as a nucleator. Especially effective as mixtures have been found to be ethylene-vinyl acetate copolymers of molecular weights from 1,200 to 6,000 having vinyl acetate contents of about 32 to 50 weight percent (e.g., about 11 to 25 mole percent ester) as wax stopper and ethylene vinyl acetate Molecular weight copolymers of about 500 to 10,000 with vinyl acetate comonomer levels of 1 to 30 weight percent (eg, about 0.3 to 12 mole percent ester) as wax growth stimulators. If the nucleator is an ethylene / vinyl acetate copolymer, then its average molecular weight is preferably at least 500-better still 1000-higher than the corresponding property of the wax-growth stopper and / or the ester content is at least 5% below the corresponding one Feature of wax growth stopper.

All molecular weights listed herein are molecular weights which are determined by vapor phase osometry (VPO), d. H. using the Mechrolab Vapor Phase Osmometer 301A. The vinyl acetate contents are determined by saponification. Thus, relative to the growth arrestor, the nucleator may include an ethylene-vinyl acetate copolymer of higher molecular weight when the vinyl acetate content of the two polymeric materials is about the same. When two synthetic polymers are used, they can be prepared separately or sequentially in a batch by varying the reaction conditions. Thus, the reaction conditions may be changed and selected such that the initial polymerization reaction produces a polymer having primary nucleator properties, whereupon the reaction conditions are changed to produce a polymer having primary wax growth inhibiting properties, or vice versa. In this way, a polymer mixture can be produced with both types of function.

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In the specific embodiment of the invention, which uses two different copolymers of ethylene and vinyl acetate, the relationships between the vinyl acetate concentration in the copolymer and the molecular weight of the copolymers are important, as these are factors that determine the RoI Ie of the individual copolymer in the fuel determine. That is, it depends on them - provided the properties of the other polymer are similar - whether the polymer as a whole functions within the composition as a wax stopper or as a wax nucleator. Thus, a very general rule of thumb is that the nucleators, i. the nucleating agents should have relatively long segments of polymethylene, and, as these synthetic polymers approach lower molecular weight regions, the proportion of vinyl acetate should also decrease. On the other hand, with increasing molecular weight, the proportion of vinyl acetate should also increase. Thus, the specific nucleating agents will contain an ethylene copolymer as well as a relatively low proportion of vinyl acetate having a relatively high molecular weight.

The wax stopper, on the other hand, will generally be a copolymer of relatively low molecular weight and relatively high vinyl acetate content, since the wax stop function is more dependent on the presence of bulky groups, such as ester groups, attached to the molecular backbone of the copolymer.

Although the separate copolymers can be mixed directly into the fuel, it will normally be desirable to make a concentrate. This can be done by first combining each of the copolymers with a separate solvent; however, in the more preferred variant, this is done by dissolving each of the copolymers in a two common solvent. Thus, both the relatively low molecular weight vinyl acetate-rich (second) copolymer and the preferred first relatively low molecular weight relatively low vinyl acetate copolymer can be dissolved in a kerosene or heavy aromatic gasoline. Preferred concentrates will contain from 5% to 60%, preferably from 10% to 50%, of the total copolymer, the balance substance being a hydrocarbon oil solvent.

The stopper copolymers can be prepared by known procedures utilizing free radical initiators, such as preferably organic peroxide compounds. Suitable processes are high temperature and high pressure processes according to US-PS, such as US Pat. Nos. 3,048,479 or 3,093,623 and British Patent 1,263,152. The fuels to which the present invention relates are thus difficult to treat with conventional additives in that they have a relatively narrow boiling range of 20% to 90% degree fraction of the fuel, wherein the 90% fraction boiling at 65 to 100 ⁰ C above that of the 20% fraction and / or in that a relatively small gap between the 90% boiling points and the final boiling point is that less than 25% and in some cases even less than 20 ⁰ C by weight.

Suitably, a total amount of from 0.001 to 0.5 mass% of additive based on the mass of the fuel is used; preferably 0.005 to 0.1 wt .-%, more preferably 0.01 to 0.04 wt .-% are used. When a mixture is used, the polymeric materials will find application in proportions of 10 to 15 mass units of growth stopper per mass fraction of nucleator.

embodiment

The present invention is illustrated by the following embodiments in which an additive of the present invention (additive A) is a 63 weight percent solution of a polymer combination of 13 weight percent wax crystal growth stopper of an ethylene-vinyl acetate copolymer of 2 500 molecular weight and 36 wt% vinyl acetate content and 1 wt% wax crystal stimulator having a molecular weight of 3500 and a vinyl acetate content of about 13 wt%.

Additive B was a 45 wt.% Oil solution of an additive combination of 3 wt. Parts of the above mentioned waxy crystal growth stopper and 1 wt. Part of the wax nucleating agent of US Patent No. 3,961,916. Additive is a 50 wt.% Oil solution of ethylene-acetate copolymer having a molecular weight of 2000 and a vinyl acetate content of 30% by mass. In the embodiments, the following fuels were used:

Fuel no. At first 20% boiling 90% boiling Endsiede boiling point Point Point Point ⁰ C ° C ⁰ C ⁰ C 1 200 248 334 360 2 228 280 351 374 3 220 266 346 367 4 224 268 341 359 5 221 259 331 361 6 244 264 336 360 7 163 240 344 362 8th 160 234 344 358 9 200 257 336 362 10 213 264 338 360

In the embodiments, the wax crystal size is measured at fast cooling rates by cold filter plugging point testing. This test is performed as described in "Journal of the Institute of Petroleum", Vol. 52, No. 510, June 1966, pages 173-185, Briefly, this test is performed on a 45 ml sample of the oil to be tested . the introduced in the ASTM cloud point peel oil is cooled in a to about -30 ⁰ F (-15 ⁰ C) held bath. Starting from 4 ° F (2 ⁰ C) above the cloud point is all 2-degree temperature drop steps the oil with a suction pressure of 8 inches of water through a filter element provided with a 350 sieve in a pipette up to a

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Volume of 20ml distinctive mark drawn, from then on the oil is allowed to return by gravity flow to the cooling chamber. The test is repeated every 2 ° C oil temperature drop off until the oil is no longer able to fill the pipette within 60s of the aforementioned mark. The results of the test are given as the cold filter clogging point, which is the highest temperature at which the oil fails to fill the pipette.

The required amounts of additive A, additive B and additive C to achieve a 6 ° C, 8 ° C and 10 ° C reduction in temperature at which these fuels would pass the cold filter plug point test were determined as follows:

burning 6 ⁰ C B C 700 8 ⁰ C B C 1O ⁰ C B C material additive 760 440 1050 n. m. 1360 n. m. A 400 - reduction 540 620 reduction 650 n. m. 1 410 700 A 850 - A 820 - 2 130 n. m. 560 n. m. 700 n.m. 3 420 n.m. 1000 190 n. m. 250 n. m. 4 700 - 900 500 - 1000 520 - 1000 5 780 - 900 800 - 950 900 - 1 100 6 250 - n.m. 840 - 1000 n. m. - 1100 7 570 - n.m. 330 - n. m. 410 - n. m. 8th 500 620 n. m. 710 n. m. 9 260 600 700 10 530 370 450 570 600

n. m. = not possible

In another series of experiments, the amount of additive required to obtain a 6 ⁰ C, 8 ° C, and 10 ° C reduction in the cold filter clogging point test value of various fuels was determined and compared to the levels for non-additive additives present invention were required

 The following fuels were used:

Fuel- At first 20 ° / No. boiling point 11 107 244 12 113 242 13 200 248 14 220 263 15 220 266 16 221 259 17 222 260 18 228 280

90%

Final Boiling Point

351 355 334 350 346 331 328 351

381 375 360 373 367 361 354 374

The additives A, B and C used in the preceding embodiment and together with the additives D to H are used in the following manner:

additives

Wt .-% relative vinyl acetate molecular mass 34.8 2 650 27.1 3170 28.9 2 590 28.2 2 940 29.9 2 300

D E F G H

The results are listed in the following table.

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Fuel number

average

Cold filter blockage point check ⁰ C depression

Amount of additive needed, ppm

11 6 45 90 35 50 100 26 40 80 8th 70 110 40 75 220 35 75 105 10 90 140 70 90 > 500 85 120 135 12 6 100 250 195 155 > 500 130 145 210 8th 160 320 200 195 > 500 200 210 270 10 180 380 350 270 > 500 275 300 350 13 6 500 750 550 650 > 2,000 650 200 1050 8th 650 800 1000 1000 > 2,000 800 300 1020 10 730 900 1080 1090 > 2,000 1000 500 1300 14 6 280 340 300 300 > 800 320 440 420 8th 350 380 400 350 > 800 420 460 450 10 370 440 470 380 > 800 500 480 480 15 6 370 460 600 500 > 1500 550 600 650 8th 450 560 710 600 > 1500 750 650 700 10 470 760 860 1060 > 1500 800 750 800 16 6 580 550 750 500 > 1850 600 1100 1000 8th 800 750 110 680 - > 2,000 700 1350 1150 10 880 880 1330 870 > 2000 850 1400 1200 17 6 600 850 1000 850 > 2,000 1350 1500 1600 8th 790 980 1300 750 > 2000 1850 2,000 2,000 10 890 1 160 1 500 920 > 2,000 > 2200 > 2000 > 2,000 18 6 140 400 370 140 > 750 700 > 750 > 750 8th 160 470 500 160 > 750 > 750 > 750 > 750 10 180 540 650 175 > 750 > 750 > 750 > 750

10

327 461 474 359 High 541 > 596 429 546 656 476 High > 688 > 718 474 650 789 607 High > 848 > 788

> 720> 828> 874

Claims (3)

-ι- 810 22 Invention claim: An additive concentrate for inclusion in distillate fuels, characterized in that it contains, dissolved in a hydrocarbon solvent, 5 to 60% by weight of a copolymer of ethylene and a vinyl ester of 1 to 4 carbon atoms, the copolymer being 32 to 35 Ma. Contains -% vinyl ester and has an average molecular weight of 1,000 to 6,000. 2. Additive concentrate according to item 1, characterized in that it is the copolymer of ethylene and the vinyl ester is a mixture of two copolymers, one of which acts as a nucleating agent for the wax crystals and the other as a growth stopper and wherein the average vinyl acetate Content of the copolymers is in the range of 32 to 35 mass%, and the average molecular weight of the two copolymers is in the range of 1,000 to 6,000. 3. A process for improving the flow properties of a petroleum distillate fuel, characterized in that its 20% and 90% distillation points differ in the range of 65 to 100 ⁰ C and / or to improve the flow properties of a distillate fuel whose 90% to the final boiling point 10 bis 20 ⁰ C, further characterized in that an additive is added to this distillate fuel, which is composed of a copolymer of ethylene and a carboxylic acid vinyl ester having 1 to 4 carbon atoms, wherein the copolymer contains 32 to 35 wt .-% vinyl ester and a average molecular weight from 1,000 to 6,000.