US3250599A - Fuels of improved low temperature pumpability - Google Patents

Description

United States Patent 3,250599 FUELS 0F IlVIPROVED LOW TEMPERATURE PUMPABILITY James H. Kirk, Dyer, Ind., and Seymour H. Patinkin, Chicago, and William L. Steiuholf, South Holland, Ill., assig'nors to Sinclair Research, Inc., Wilmington, Del., a corporation of Delaware No Drawing. Filed Dec. 3, 1962, Ser. No. 241,493

9 Claims. (Cl. 44-62) This invention relates to a distillate fuel oil composition having improved pumpability characteristics at low temperatures. More particularly, the present invention is directed to a distillate fuel oil boiling above the gasoline range containing a novel combination of additives that endows the fuel oil with improved pumpability properties over a wide low temperature range.

When fuels are to be used or stored under low temperatures such as from the cloud point of the fuels to 15 F. or below, it has become common practice to incorporate small amounts of a pour depressor. Although pour depressor additives assist in lowering the temperature at which the fuel will flow under standard conditions, we have found, in confirmation of the work of other researchers in this art, that ASTM pour points do not correlate with the actual pumpability characterics of the fuel. For example, the addition to distillate fuels boiling above the gasoline range of small, economically feasible concentrations of a copolymer of ethylene and vinyl acetate, a commonly employed pour point depressor, generally provides a significant reduction in the pour point of the fuels yet at temperatures near or slightly below the natural pour point of the fuel, the additive frequently has a highly detrimental effect on the pumpability of the fuel. To further complicate matters, it is not unusual at much lower temperatures, say l F. or lower, for the same concentration of this pour depressor to improve pumpability. It is apparent, therefore, that pour depressors such as the copolymers of ethylene and vinyl acetate, in economically feasible concentrations, will not provide a fuel with satisfactory pumpability characteristics over a wide range of low temperatures. Since low temperature climatic conditions to which fuels may be subjected vary from day to day over a wide range and cannot be controlled without the use of additional expensive equipment, the desirability of a distillate fuel possessing excellent pumpability throughout the wide range of low temperatures becomes quite evident.

A small degree of success has been experienced in alleviating this pumpability problem by employing relatively high concentrations of pourdepressors including the aforementioned copolymer of ethylene and vinyl acetate, but the satisfactory results appear limited to certain fuels since the same or higher concentrations are not adequate in many other fuels. In any event, concentrations of the pour depressor required to provide the desired pumpability even in the fuels where they are effective, are so high as to mitigate their use for economic reasons.

It has now been found that a petroleum distillate fuel composition having excellent pumpability over a wide range of low temperatures, say from the cloud point of give a variety of microcrystalline waxes.

3,250,599 Patented May 10, 1966 the fuel to 15 F. or below, can be obtained by adding to the fuel at least about 0.001, often about 0.002 to 0.5, volume percent of a fuel oil-soluble copolymer of ethylene and a vinyl fatty acid ester having from about 3 to 5 carbon atoms, and about 0.05 to 0.4, preferably about 0.1 to.0.3 volume percent of petroleum microcrystalline wax, for instance petrolatum. Preferably the amount of copolymer used is about 0.005 to 0.02 volume percent. That the addition of petrolatum to a distillate fuel con taining small amounts of the ethylene-vinyl 'fatty acid ester copolymer will provide the desired pumpability over the wide range of low temperatures is surprising in that petrolatum, first of all, is not a pour point depressor and in fact may even raise the pour point of the fuels. Secondly, when petrolatum is added to the fuelpin the absence of other additives at low temperature, e.g. at l5 F. the pumpability of the fuel is frequently degraded. In addition to the advantageous low temperature pumpability properties exhibited by the fuel compositions of the present invention, they also have substantially improved pour properties.

The copolymers of ethylene and vinyl fatty acid esters of about 3 to 5 carbon atoms employed in the additive combination of the present invention are well-known distillate fuel oil pour point depressors and can be prepared by various methods. The copolymers are preferably composed of about 60 to 99%, preferably about 90 to by weight of ethylene and about 1 to 40%, preferably about 10 to 30%, by weight of the vinyl fatty acid ester and have a molecular Weight, as determined by the K. Rasts method (Ber. 55, 1051, 3727 (1922)), usually ranging from about 1,000 to 3,000, preferably about 1,500 to 2,200. An especially useful copolymer is ethylene-vinyl acetate,rparticularly the copolymer containing about ,15 to 25% byweight vinyl acetate, for example 20% by weight vinyl acetate. Copolymers of this type are described in US. Patents 3,037,850 and 3,048,- 479, herein incorporated by reference.

The petroleum microcrystalline wax of the present invention includes those hydrocarbon waxes which are normally derived from heavy lubricating oil fractions obtained from parafiin and mixed base crude oils and which waxes have a fine, less apparent crystalline struc ture than paraffin Wax. The wax can be in the form of petrolatum wax which generally contains up to 40% oil, more-often about 5 to 25%, or the wax may be in the more refined or deoiled form. In the derivation of the microcrystalline waxes the heavy lubricating oil stocks, preferably those stocks non-d'istillable from petroleum by normal means, i.e. residual stocks, may first be subjected to solvent deasphalting, solvent refining with phenol or other solvents selective for aromatics or hydrotreating, and then to the normal dewaxing and deoiling procedures to produce the wax. Dewaxing may be accomplished by any one of a number of suit-able processes including solvent extraction at low temperatures followed by crystallization and separation by centrifugation or by solvent dewaxing with methyl-ethylketone solutions. The resulting petrolatum wax may, if desired, be further deoiled as by methylethyleketone treatment to The wax may also be obtained as foots waxes or foots oils during the manufacture of other microcrystalline Waxes.

. 3 a 4 The hydrocarbon fuel oils which are improved in ac- Distillation, F.Cntinued cordance with this invention are the normally liquid 10 370 petroleum distillates boiling primarily above the gaso- 20 410 line range and include, for example, diesel fuels, heating 30 449 oils, etc. These oils are usually petroleum middle dis- 5 40 486 tillates, which generally boil primarily in the .range of 50 514 about 250 to 750 F., and commonly have relatively 60 542, high pour points, for instance, at least at l0 F. or 70 569 higher. The oils can be in their relatively crude state 80 596 or they can be treated in accordance with well-known 9O 626 commercial methods such as acid or caustic treatment, E.P. 652 solvent refining, hydrotreating etc. The fuel oils can Res. 2.0 figg g gfgfi g g il g gf i fii if gg ii sg Various commercially available petrolatums designated fuel oils, naphthas and the like with cracked distillate 2 3 333 g g f g g :2 .2.52 325 g g gg gg stocks. The cracked materials will frequently be about h T H y A p 15 to 70 volume percent of the fuel. t e if are 8 Own m i g t e i 1 2 58- The additives of the present invention can be added as ggig g 32 132223.??? i e g a so 6 use is e such to the distillate fuels or if desired as an additive con- 'centrate of the petroleum microcrystalline wax and co- Table 11 polymer of ethylene and vinyl fatty acid ester in a. ratio WAX ADDITIVES of about 1 to 50 volume parts of the wax to 1 volume part to the copolymer, preferably about 5 to 30 parts of Foots oil the wax to 1 part of the copolymer. The additive mixgz g- 23E 3 g ture, per se can be added to the distillate fuel or as a 25 um um mgstsnme solution in a normally liquid petroleum hydrocarbon, Wax for example, distillate fuels such as kerosene in concen- I trations of say about 20 to 60 volume percent, preferably Gravity Q 32.7 up to about 50% of the combined additives. afifigglf fig fi 3? 33 2 it? The following examples are included to further illusf 210;) (Saybolt) 12% 95 85.2% 10%.; trate the'present invention. gglg g fi%f{f; 5 5 540 5 EXAMPLES nfiif as "55a "at "at "as No. 2 fuel oil compositions containing small concen- 8 1 45353 -355, trations of either a copolymer of ethylene and vinyl ace- 5 M.W I: 800-850 tate, a petroleum microcrystalline Wax or a combination 3 Type 0) (2) (9 (2) of the two additives were subjected to a pumpabi-l'ity test I over a temperature range of +10 F. to +-1S F. For PennSyhTama' zMldcmtment' comparison the neat fuel oil was also subjected to the test. The No. 2 fuel oil employed inall the runs analyzed 40 The pumpability test employed comprises the followas follows. ing:

Table I 40 gallons of the fuel composition tested was placed in Composition: a 275-gallon fuel storage tank in a cold room, maintained Naphtha 13 at a constant temperature of either +10 F., 0 F., -8 water White distillate Plus gas 01 53 F. or -15 F., and the tank was manifolded to a home Light cycle 011 22 burner pump located in an adjacent warm room at normal P r ffi i hydrocarbons (CFCQ) 2 temperatures. Immediately preceding the pump in t e Laboratory Sty a warm room was a filter. The test fuel was routed from Gravity 0 A 34 4 the pump under a pressure of 100 p.s.i. through a total Flash .3 F PM '7' gallonage meter to a .75 g.p.h. nozzle, thence to discard. 2 622 The pump was operated on a 20-minutes on, l0-minutes Cloud point 0 F otr basis, starting immediately after charging the fuel to Pour Point F +5 the tank. Pumpability failure was taken as the point when olefins 'g z u 0 2 fuel ceased to be pumped over a time period of at least 30 Aromafics 5 p I minutes, and the percentage of initial fuel oil charge o '7" 7 removed from the tank was determined. The results of Dlsnnanoni the tests, the concentration of additives utilized and the I.B.P. 322 pour and cloud points of the compositions are shown in 5 percent 348 Table III.

' Table 111 Vol. percent Percent fuel removed pour Vol. percent Cloud/pour, depressant 1 petrolatum F.

+10 F. 0 F. -15 F.

+10/+5 21. s 40. 0 +1s/+5 +17/-1s 88.0 +171-23 44. 2 s9. 2 +1s/50 0.2 A +16l-j-l0 98.8 27.5 0.3 B +141+10 1.5 0.2 C +l6l+5 97.5 0.3 B +16l+5 0.05 A +161-10 400,300 0.1 A +1010 69.8 56.5 0.1 A +171-20 96.0 90.7 0.3 B +l6l-5 1 50% kerosene solution of the ethylene-vinyl acetate copolymer characterized by containlng about 20% ethylene and having a molecular weight of about 1800.

Concentrates of a combination of the additives can be prepared for instance by adding to this solution petroleum microcrystalline wax in amounts and ratios to the copolymer as indicated in Table III above.

Examination of the data of Table III reveals that small concentrations of the ethylene-vinyl acetate copolymer alone do not provide improved pumpability over the entire low temperature range. Note that at F., for example, small concentrations of copolymer were actually detrimental to pumpability. Also that data demonstrate that microcrystalline wax is not a pour point improver and does not provide improved pumpability over the entire range of low temperatures. The fuel oil containing small concentrations of a combination of the copolymer and microcrystalline Wax are shown to exhibit surprising pumpability characteristics throughout the range of low temperature conditions.

We claim:

1. A fuel oil composition having improved pumpability over a wide range of low temperatures consisting essentially of a petroleum distill-ate fuel boiling above the gasoline range having incorporated therein about 0.001 to 0.5 volume percent of a copolymer of about 60 to 99% by weight ethylene and about 1 to 40% by weight of a vinyl fatty acid ester of about 3 to 5 carbon atoms, said copolymer having a molecular weight of about 1,000 to 3,000, and about 0.05 to 0.4 volume percent of a petroleum microcrystalline wax, said amounts improving the low temperature pumpability of the fuel.

2. The composition of claim 1 wherein the copolymer consists essentially of about 70 to 90% of ethylene and about to 30% of the vinyl fatty acid ester.

3. The composition of claim 2 wherein the amount of the copolymer is about 0.005 to 0.02 volume percent.

4. The composition of claim 3 wherein the vinyl fatty acid ester is vinyl acetate and is about 15 to 25% of the copolymer.

5. The composition of claim 4 wherein the amount of petroleum microcrystalline wax is about 0.1 to 0.3 volume percent.

6. A composition consisting essentially of petroleum microcrystalline wax and a copolymer of about 60 to 99% by weight ethylene and about 1 to by weight of a vinyl fatty acid ester of about 3 to 5 carbon atoms, said copolymer having a molecular weight of about 1,000 to 3,000, and the ratio of said wax to said copolymer being about 1 to volume parts to 1 volume part.

7. The composition of claim 6 wherein the ratio of petroleum microcrystalline wax to said copolymer is about 5 to 30 volume parts to 1 volume part.

8. The composition of claim 7 wherein the copolymer consists essentially of about to of ethylene and about 10 to 30% of the vinyl fatty acid ester.

9. The composition of claim 8 wherein the vinyl fatty acid ester is vinyl acetate and is about 15 to 25 of the copolymer.

References Cited by the Examiner UNITED STATES PATENTS 2,615,799 10/1952 Martin 44-27 2,917,375 12/1959 Hudson 4462 2,967,816 1/1961 Hudson 44-62 X 3,048,479 8/1962 Ilnyckyj 4462 DANIEL E. WYMAN, Primary Examiner. C. O. THOMAS, Y. M. HARRIS, Assistant Examiners.

Claims (1)

1. A FUEL OIL COMPOSITION HAVING IMPROVED PUMPABILITY OVER A WIDER RANGE OF LOW TEMPERATURES CONSISTING ESSENTIALLY OF A PETROLEUM DISTILLATE FUEL BOILING ABOVE THE GASOLINE RANGE HAVING INCORPORATED THEREIN ABOUT 0.001 TO 0.5 VOLUME PERCENT OF A COPOLYMER OF ABOUT 60 TO 99% BY WEIGHT ETHYLENE AND ABOUT 1 TO 40% BY WEIGHT OF A VINYL FATTY ACID ESTER OF ABOUT 3 TO 5 CARBON ATOMS, SAID COPOLYMER HAVING A MOLECULAR WEIGHT OF ABOUT 1,000 TO 3,000, AND ABOUT 0.05 TO 0.4 VOLUME PERCENT OF A PETROLEUM MICROCRYSTALLINE WAX, SAID AMOUNTS IMPROVING THE LOW TEMPERATURE PUMPABILITY OF THE FUEL.