KR910004942B1 - Middle distillate compositions with improved low temperature flow properties - 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

Intermediate Outflow Compositions with Improved Low Temperature Flowability

Mineral oil containing paraffin wax has the property that fluidity decreases as the temperature of oil decreases. This loss of fluidity is due to the crystallization of the wax into plate-like crystals, which eventually form spongy masses containing oil therein.

Various compositions that act as wax crystal modifications when mixed with waxy mineral oils have long been known.

Such compositions modify the size and shape of the wax crystals and reduce the adhesion between the wax and the oil so that the oil still has flowability at low temperatures.

Various pour point depressants have been described in the literature and are used commercially. U.S. Patent No. 3048479, for example, shows that a copolymer of ethylene and C ₃ -C ₅ vinyl esters, such as pour point depressants for fuels, especially heating oils, diesel and jet fuels, such as vinyl acetate, is used. Hydrocarbon polymer pour point depressants, for example based on higher alpha-olefins such as ethylene and propylene, are also known. US Pat. No. 3,619,616 relates to the use of mixtures of copolymers, one of which is a wax crystal nucleating agent and the other is a growth inhibitor that controls the size of the wax crystals. Similarly, British Patent 11263152 shows that the size of the wax crystals can be controlled by using copolymers having lower branched chains.

The increased diversity in effluent fuels has resulted in fuels that cannot be treated with existing additives or that require uneconomically high levels of additives. One particular group of fuels in which such problems exist is to have a relatively narrow boiling range. The fuel is often characterized by its initial boiling point, the final boiling point and the intermediate temperature at which a certain volume percentage of the initial fuel is distilled off. Fuel oils with 20% and 90% distillation points which differ in the range of 65-100 ° C., in particular 70-100 ° C. and whose 90% boiling temperature is generally 10-30 ° C. and especially 10-25 ° C. of the final boiling point are additives or other very high It is known to be particularly difficult to treat because it is not actually affected by the additives. All distillation referenced herein is in accordance with ASTM D86.

Moreover, as the price of crude oil rises, so-called "sharp fractionation" methods are used to regenerate effluent fuels that cannot be processed with conventional additives or that are economically unacceptable. Optimizing operations and increasing the production of effluent fuels has become an important issue. Typically a “shop fractionation” treated fuel has a 90% -final boiling point of 10-20 ° C. and a 20-90% boiling range of 90-110 ° C. Both types of fuel have a final boiling point of 350 ° C. or higher, generally in the range of 350 ° C.-375 ° C., in particular a 350-370 ° C. final boiling point.

Copolymers of ethylene and vinyl acetate, which have been widely used to improve the flowability of effluent fuels, which are already widely used, generally contain up to about 30% by weight of vinyl acetate, with the additive being a wax crystal formed in the fuel. It is also used to control the size of and also contains about 36% by weight or more of vinyl acetate, where their first function is to lower the pour point of the effluent fuel. None of these types of additives have been found to be effective in treating narrow boiling points and / or shop fractionated fuels as described above.

However, the inventors have found that copolymers containing 32-35% by weight of vinyl esters and having a number average molecular weight of 1000-6000 and composed of vinyl esters of ethylene and vinyl esters of carboxylic acids of 1-4 carbon atoms are used to treat these fuels. It was found to be particularly effective.

Therefore, the present invention is directed to improving the fluidity of different petroleum spilled fuel oils within the range of 65-100 ° C. with 20% and 90% distillation point and / or having a 90% final boiling point of 10-20 ° C. It provides a use as an additive to improve the flowability of effluent fuels, wherein the additive contains 32-35% by weight of vinyl esters and carboxylic acids of 1-4 carbon atoms with ethylene having a number average molecular weight of 1000-6000 Copolymers of vinyl esters thereof.

Furthermore, the present invention shows that 20% and 90% distillation points differ by 65-100 ° C. and 90% boiling temperature is 10-30 ° C. and / or 90% -final boiling point is 10-20 ° C. and 32-35 weight of the final boiling point. Provides effluent fuel containing 50-500 ppm (in millions of parts per million) of copolymer comprising vinyl ester of% and a vinyl ester of ethylene and carboxylic acid of 1-4 carbon atoms having a number average molecular weight of 1000-6000 do.

Copolymers of ethylene and vinyl esters of carboxylic acids may be mixtures of two copolymers as generally described in US Pat. No. 3,391,616 and may or may not contain the same vinyl ester. In particular, the inventors have found that additive combinations containing at least 10 parts by weight of growth inhibitors per weight part of each wax crystal nucleating agent are suitable for treating this type of fuel. Mixtures are particularly useful because they permit added flexibility.

Preferred embodiments of the invention have different oil spilled fuel oils and / or 90% boiling temperatures in the range of 20% -90% distillation point of 65-100 ° C, 10-30 ° C preferably 10-20 ° C of the final boiling point. It provides a use as an additive for improving the flowability of the effluent fuel, the additive comprises 10-15 parts of the synthetic polymer having the properties of the wax growth inhibitor in the fuel for each part of the synthetic polymer having the properties of the wax growth accelerator and Wax growth inhibitors and growth promoters are copolymers of vinyl esters of ethylene and 1-4 carbon atoms of carboxylic acid having an average ester content of 32-35% by weight and a number average molecular weight of 1000-6000.

Another embodiment of the present invention provides a effluent fuel having a 20% -90% boiling oil with different effluent fuel and / or a 90% -final boiling point 10-20 ° C. in boiling point by 65-100 ° C., which is a wax growth. Each part of the synthetic polymer having the properties of the accelerator contains 50-5000 ppm of an additive mixture having 10-15 parts by weight of the synthetic polymer having the property of the wax growth inhibitor in the fuel. The growth inhibitor and the growth promoter have 1 to 4 carbon sources. Copolymers of ethylene and vinyl esters of carboxylic acids with an average ester content of the polymer in the range of 32-35% by weight and their number average molecular weight of 1000-6000.

Fuels having a 20% -90% distillation point different in the range of 65-100 ° C and a 90% boiling temperature are generally 10-30 ° C of the final boiling point are usually at least 350 ° C and usually 350 ° C-375 ° C more typically It has a final boiling point of 350 ° C.-370 ° C. A fuel with a 90% final boiling point of 10 ° -20 ° C typically has a 20-90% distillation range in the range of 90 ° C-11O ° C and generally above 350 ° C, usually 350 ° C-375 ° C and more typically 350 ° C- It has a final boiling point of 370 ° C.

When the additive is a mixture, the wax growth promoter or nucleating agent is a synthetic polymer that is soluble in the effluent at temperatures above the saturation temperature. For example, when the temperature of the effluent approaches the saturation point, it slightly exceeds the saturation temperature (eg, 10 ° C. or higher; Preferably, when the effluent is cooled, it is gradually separated out in the form of small particles. "Saturation temperature" is defined as the lowest temperature at which a solute, such as, for example, a wax, cannot be crystallized from solution even if known crystallization induction methods are used. As cooling continues, it is not known that additional nucleating particles are separated out in more or less continuous ways. These additional particles act as nucleating agents for continuous wax crystallization, which serves to significantly prevent overcooling of the effluent. The advantage of the progressively formed new nucleator particles is that n-paraffins maintain the supersaturation of the effluent at the lowest possible level, causing the growth inhibitor's molecules to grow in the center of the growing crystals, thus stopping further growth.

The inhibitory effect of growth inhibitory agents is believed to result from the presence of large groups in the molecule. Additional nucleating agents separate the deactivated growth centers to replace. Wax growth inhibitors are more soluble in the effluent than the nucleating agent and act as growth inhibitors when wax crystals form.

The nucleating agent should be insoluble in the effluent at elevated temperatures and should not begin separation at temperatures significantly above that for which wax crystallization can occur. If the nucleating agent is separated off at a temperature significantly above the temperature at which crystallization can occur, the nucleating agent tends to sink to the bottom of the vessel with the effluent instead of remaining dispersed in the effluent. This factor is particularly important if the effluent does not have the proper redispersion of nucleating particles in the effluent and the effluent has to be warmed and cooled repeatedly, such as during the warm and cold part of the day. Synthetic polymers used as wax growth inhibitors and wax growth inhibitors may contain the same or different vinyl esters.

For the purposes of the present invention, the wax crystal growth accelerator, the wax nucleating agent and the nucleating agent for the wax are all considered in the same term and used interchangeably.

Wax growth inhibitors (hereinafter sometimes referred to as wax inhibitors) generally include a waxy polymethylene moiety that can place itself in the lattice of the wax crystal at its lattice potential in its molecular structure. It also contains large groups that stop further crystal growth by interfering with the activity of the n-paraffin molecules at the lattice potential point.

Preferred synthetic polymer wax nucleating agents contain a transparent vessel containing 0.1-3.0% by weight of a solution of potential nucleating agent in the effluent with the same effluent and the same vessel without the additives and the temperature of the two materials. By descending it can be chosen by eye comparison. Initiation of wax crystallization from an effluent containing polymeric material having nucleating agent properties occurs at a higher temperature than crystallization starts to occur in the absence of the nucleating agent. Similarly, wax inhibitors are characterized for use in delaying the onset of crystallization.

Synthetic polymers used as nucleating agents and wax growth inhibitors are copolymers of ethylene and vinyl esters and may contain the same or different ester monomers.

Vinyl ester content and molecular weight are averages of the mixtures with preferred additives which are mixtures of the abovementioned polymers. However, the adduct may also be a homopolymer, which means a material produced in a single polymerization process. The material in this example can be obtained by known high pressure or solution polymerization techniques which have been proposed preliminarily for the production of ethylene vinyl esters, especially vinyl acetate copolymers, for fuel additives.

Suitable vinyl esters for mixtures and homopolymers include vinyl acetate, vinyl propionate and vinyl butyrate.

When combined with effluent fuel, improved fluidity is effective under the following conditions:

1. Maintain this fuel fluid at operating temperature.

2. "Oil in bulk" inhibits the growth of separated wax crystals when the oil is slowly cooled, such as the typical rate encountered when exposed to cold atmosphere, for example, 0.2 ° F-2 ° F / hr. .

3. When the oil is rapidly cooled, such as 10 ° F-100 ° F / hr /, which is a typical rate encountered when a relatively warm oil enters the delivery conduit and is suddenly exposed to low temperatures, it inhibits the growth of the separated wax crystals.

The three items cited above are preferred to show that the fuel can be pumped and filtered under its dispersion and application conditions.

As mentioned, when a mixture of polymers is used the molecular weight is the average of the two polymers and generally the preferred number average molecular weight (VPO) for the nucleating agent is in the range of 500-6000 and more preferably in the range of 1200-6000. For example, it has been found that relatively low molecular weight ethylene vinyl ester copolymers, especially with relatively high vinyl ester content, act as wax growth inhibitors. In other words, a relatively high molecular weight copolymer of vinyl ester and ethylene, which copolymer has a relatively small amount of vinyl ester, acts as nucleating agent. More specifically, as a wax inhibitor, as a wax growth promoter and an ethylene / vinyl acetate copolymer having a number average molecular weight of 1200-6000 (VPO) having a vinyl acetate content of about 32-50% by weight (such as 11-25 mole% ester). Mixtures containing ethylene / vinyl acetate copolymers of about 500-10,000 (VPO) number average molecular weight having vinyl acetate comonomers at a weight ratio of about 1-30% by weight (such as 0.3-12 mole% ester) are very effective. Found.

If the nucleating agent is an ethylene / vinyl acetate copolymer its number average molecular weight is at least 500, preferably 1000 and the ester content is at least 5% lower and / or higher than the corresponding properties of the wax growth inhibitor.

All molecular weights specified herein are “number average molecular weight” and this is the molecular weight as measured by a vapor phase osmometer (VPO), such as using Mechrolab Vapor Osmometer 301A. Vinyl acetate content is determined by saponification. Therefore, with regard to growth inhibitors, the nucleating agent may comprise higher molecular weight ethylene-vinyl acetate copolymers if the vinyl acetate content of both polymerizer materials is the same. If two synthetic polymers are used they can be made individually or in succession by changing the reaction conditions in one bath. The reaction conditions can therefore be chosen such that the initial polymerization can produce polymers with preferential nucleating agent properties and the reaction conditions are modified to produce polymers with wax growth inhibitory properties (or vice versa). Can be. In a similar manner, mixtures of polymers may be produced with both forms of function.

In certain embodiments of the invention, which include two different copolymers of ethylene and vinyl acetate, the relationship between the concentration of vinyl acetate in the copolymer and the molecular weight of the copolymer is a factor that determines the role of a particular copolymer in the fuel. It is important. That is, they determine that the given polymer properties are similar whether the copolymer is performed as a wax inhibitor or wax nucleating agent in the composition as a whole. Therefore, in general, the nucleating agent should have a relatively long polyethylene moiety and the vinyl acetate ratio should be reduced when such synthetic polymers approach a low molecular weight range. In other words, as the molecular weight increases, the proportion of vinyl acetate must also decrease. Therefore, certain wax nucleating agents will comprise a relatively small fraction of copolymers of vinyl acetate and ethylene having a relatively high molecular weight.

Wax inhibitors will generally be relatively low molecular weight copolymers of relatively high vinyl acetate content because the inhibitory function of the wax depends on the presence of large groups such as, for example, ester groups attached to the stem of the copolymer molecule.

It has been found that the separation copolymer can be mixed directly into the fuel but is preferably made from concentrate. This can be done by first bonding each to a separate solvent, most preferably dissolving each in a conventional solvent. Therefore, both the relatively low molecular weight higher vinyl acetate (second) copolymer and the first relatively high molecular weight lower vinyl acetate copolymer can be dissolved in kerosene or heavy aromatic naphtha. Preferred concentrates comprise 5-60%, preferably 10-50% of the total polymer in combination with the hydrocarbon oil solvent.

Inhibitor copolymers may be prepared by known processes that include free radical initiators, preferably organic peroxide compounds. Suitable processes are high temperature and high pressure or solution processes, such as in US Pat. No. 304,8479 or 3093623, and in British Patent 11263152.

The fuels involved in the present invention have a 20% -90% fraction of fuel, a relatively narrow boiling range of 90% fraction and / or 90% boiling point and / or less than 25 ° C, even at 65-100 ° C boiling above 20% fraction. In some cases it is difficult to treat with conventional additives because of the relatively small differences between final boiling points of less than 20 ° C.

Suitably, there are a total of 0.001% to 0.5% by weight of the additive based on the weight of the fuel. Preferably 0.005-0.1%, most preferably 0.01-0.04% and all percentages are weight percentages. When a mixture is used, the polymeric material is used in a ratio of 10-15 parts by weight of the growth inhibitors unjustly the nucleating agent.

The present invention is illustrated by the following examples, wherein the additive (additive A) of the present invention is 13 parts by weight of a wax crystal growth inhibitor containing an ethylene vinyl acetate copolymer having a number average molecular weight of 2500 and a vinyl acetate content of 36% by weight. And a 63% by weight binder of a polymer comprising 1 part by weight of a wax crystal accelerator having a number average molecular weight of 3500 and a vinyl acetate content of about 13% by weight, and additive B is 1 weight in accordance with US Pat. An oil solution containing a negative wax crystal catalyst and 45 parts by weight of an additive combination of 3 parts by weight of the above-described wax crystalline growth inhibitor. Additive C is a 50 wt% solution in oil of an ethylene acetate copolymer having a number average molecular weight of 2000 and a vinyl acetate content of 30 wt%.

The fuel used in the examples is as follows.

In the examples the wax crystal size at fast cooling rates is measured by Cold Filter Plugging Poi-nt (CFPP) test. This test is carried out by the process described in "Journal of the Institute of Petroleum", Vol. 52, No. 510, June 1966, pages 173-185. In short, the CFPP test is run with 45 ml of oil sample to be tested. The oil located in the ASTM cloud point jar is cooled in a bath maintained at about -30 ° F. Every 2 degrees drop at temperatures starting from 4 ° F above the cloud point, the oil enters a pipette labeled 20 ml in volume upon inhalation of 8 inches of water through a filter section equipped with a 350 mesh screen. At this time, the oil flows back to the cooling room by gravity. This test is repeated until no oil fills the pipette within 60 seconds until the indication above. The result of the test is recorded as a Cold Filter Plugging Point, which is the highest temperature at which the oil will not fill the pipette.

The amounts of Additive A, Additive B, and Additive C needed to achieve 6 ° C, 8 ° C, and 10 ° C reductions in temperature at which these fuels pass the CFPP test are determined as follows.

In a further series of experiments the amount of additive needed to provide 6,8 and 10 ° C. reductions in the CFPP values of the various fuels was tested and compared to the amount needed for additives other than the present invention.

The fuel used was:

And in additive D used with A, B, C as used in the previous examples, H is as follows:

The results are shown in the following table.

Required amount of additives (p.p.m)

Claims (9)

Ethylene having 20% and 90% distillation points different from 65-100 ° C. and / or 90% final boiling temperature 10-20 ° C., containing 32-35% by weight vinyl esters and having a number average molecular weight of 1000-6000; Effluent fuel containing 50-500 ppm of copolymers of vinyl esters of carboxylic acids of 1-4 carbon atoms. The effluent fuel according to claim 1, wherein the final boiling point is 350-375 ° C. The effluent fuel according to claim 1 or 2, wherein the 20% distillation point is different from 65-100 ° C and the 90% boiling point is 10-30 ° C of the final boiling point. The wax of any of claims 1 to 3, wherein the copolymer of ethylene and vinyl esters acts as a wax crystal promoter and the other has a 32-35 wt% average vinyl ester content and has a 1000-6000 average molecular weight wax. Spill fuel, a mixture of two copolymers that acts as a crystal growth inhibitor. 5. The effluent fuel according to claim 4, wherein the mixture comprises at least 10 parts by weight of growth inhibitor for each part by weight of accelerator. 6. The effluent fuel according to any of claims 1 to 5, wherein the vinyl ester is vinyl acetate. The effluent fuel according to claim 1, wherein the fuel oil has a 20% -90% distillation range of 70-100 ° C. and a 90% final boiling point of 10-25 ° C. 6. Incorporation into an effluent fuel consisting of a solution in a hydrocarbon solvent of a vinyl ester containing 32-35% by weight vinyl ester and having 1-4 carbon atoms having a number average molecular weight of 1000-6000 and a 5-60% by weight copolymer of ethylene Suitable additive concentrate. The copolymer of ethylene and vinyl ester according to claim 8, wherein the copolymer has a number average vinyl acetate content of 32-35% by weight, the number average molecular weight of the two copolymers is 1000-6000, and as a wax crystal promoter Additive concentrate, which is a mixture of two copolymers that act as growth inhibitors.