US3308051A - Fuel containing a solvent extract pour point depressant - Google Patents

Description

Patented Mar. 7, 1967 1 3,308,051 FUEL CONTAINING A SOLVENT EXTRACT POUR POINT DEPRESSANT Eugene M. Fauber, Hammond, Ind, assignor to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed June 1, 1964, Ser. No. 371,820 2 Claims. (Cl. 208-15) Thisinvention is directed to distillate fuel oil compositions having an improved pour point. More particularly, the invention relates to a distillate fuel oil boiling above the gasoline range containing as an additive a select amount of a deasphalted residual oil.

When fuels are to be used or stored under low temperatures, it has become common practice to incorporate small amounts of a pour depressor. I have now discovered that a deasphalted residual oil when added to the distillate fuel in a particular amount reduces the pour point of the fuel. In addition, the novel additive of the invention improves the cloud point and color stability of the fuel.

The deasphalted residual oil of the present invention is the oil'extract boiling primarily in the rang-e of about 750 F. to 1050 F. at 40% overhead and having a viscosity at 210 F. of at least about 200 F. up to say about 250 F. or more, removed from Mid-Continent 'asphaltic residuals by solvent extraction with a paraffinic hydrocarbon solvent having about 3 to 5 carbon atoms.

The Mid-Continent feeds from which the deasphalted residual oil is obtained comprise petroleum asphalt residua which may be exemplified by vacuum residua, atmospheric residua, tars, pitches, etc. boiling primarily above about 750 F. or even above about 800 F. The preferred residual feed often has an API gravity in the range of about 8 to 14, Conradson carbon content in the range of about 7 to 12 weight percent and a viscosity above about 1600 SUS at 210 F., preferably up to about 2200 SUS at 210 F.

The conditions used in the solvent extraction deasphalting step can vary depending on the boiling point of the residual feed and are ordinarily selected to provide a deasphalted extract oil yield of at least about 35% up to 60% or more. The minimum temperature used in the solvent extraction will be the softening point of the asphalt feed while the maximum will be the boiling temperature of the solvent at the pressure used. The extraction step is frequently performed at a temperature of about 100 to 200 F. There may be a temperature gradient in the deasphalting step with the highest temperature found at the deasphalted oil (extract phase) outlet. A temperature gradient of about 25 F. to 50 F. is preferably maintained. Normal operating pressures should be higher than the vapor pressure of the solvent system used at the temperature of operation. The extraction can be carried out as a single or plurality of extractions in one vessel or a plurality of vessels.

The hydrocarbon solvent used for the extraction includes propane, butane, pentane, etc. or combinations thereof. The preferred solvent is propane. After the contacting, the mixture of residual feed and solvent is separated into an extract phase containing the solvent and extracted oil components and a raffinate or asphalt bottoms phase. The two phases are separately withdrawn and the hydrocarbon solvent removed, for instance, for vaporization to provide the deasphalted extract oil of the invention. The amount of hydrocarbon solvent employed in the extraction may be within the range of about 2 to 20 volumes of solvent per volume of asphalt residual feed, preferably about 5 to 9 volumes of solvent per volume of feed.

The amount of deasphalted extract oil added to the fuel oils of the invention is important. It has been found essential to add about 1, e.g. about 0.75 to 1.25, volume percent of the deasphalted extract oil in order to reduce the pour point of distillate fuel oils. Amounts of about 0.5 and 2.5 volume percent fail to reduce either the pour point or cloud point.

The hydrocarbon fuels which are improved in accordance with the present invention include the normally liquid petroleum distillates boiling primarily above the gasoline range and include, for example, diesel fuels, heating oils, etc. These oils are usually petroleum middle distillates which generally boil primarily in the range of about 250 to 750 F., and commonly have relatively high pour points, for instance, at least at -10 F. or higher. The oils can be in their relatively crude state or they can be treated in accordance with well-known commercial methods such as acid or caustic treatment, solvent refining, hydrotreating, etc. The fuel oils can contain straight run distillate fuel oils, catalytically or thermally cracked fuel oils or mixtures of straight run fuel oils, naphthas and'the like with cracked distillate stocks. The cracked materials will frequently be about 15 to 20 volume percent of the fuel.

The following examples are included to further illustrate the present invention.

Example I Four Mid-Continent asphalt residual fractions, A, B, C and D, boiling above 740 F. and having the characteristics shown in Table I below were extracted countercurrently in a tower with propane under the extraction conditions shown in Table I. Tests on the deasphalted extract oils (D.A. oils) obtained are also summarized in Table I.

TABLE I A B C D Feedstock to Propane Unit:

APi Gravity 15. 5 14. 5 12. 6 12. 6 SSU VlS. at 210 F 800 1,400 2,072 2,072 Propane Unit Operating Conditions:

Solvent; to Oil Ratio 7/1 8/1 6. 7/1 7.3/1 Temperature, F.:

Top 165 160 147 155 Bottom 125 123 109 109 Approx. Stag 2 2 2 2 Feed Rate, b./d. 5,000 5, 000 0,050 5,500 Tower Diameter, ft 10 10 10 10 Yield of Deasphalted Extract Oil, Vol. percent 55 50 42. 6 41. 0 Tests on Deasphalted Extract Oils:

API Gravity- 24. 3 23. 2 22. 4 22. 8 SSU vis. at 210 F 194 231. 7 204. 0 Pour Point, 120 120 Clay Gel Analysis:

saturates 53. 9 52. 4 47. 4 49. 1 Aromatics. 38. 6 37. 7 40. 8 40. 2 Resms 7. 5 9. 9 11.8 10. 7

The deasphalted extract oils thus obtained were each added in amounts of 0.5%, 1.0% and 2.5% by volume to a No. 2 fuel composed of 65% gas oil, 31% light cycle oil and 5% kerosene, and having a distillation range of from 305 to 618 F. The pour, cloud and haze points of the deasphalted extraction oil-containing fuel samples were determined. The results are given in Table II and include the pour and cloud point of the No. 2 fuel for purposes of comparison.

TABLE II Blend Number Composition of Blend:

N0. 2 Fuel (Neat), Vol. Percent D.A. Oil A, Vol. Percent D.A. Oil 13, Vol. Percent". DlA. Oil 0, Vol. Pereent D.A. Oil D, Vol. Percent.

Tests on Blends:

Haze Point, F Cloud Point, F .r. Pour Point, F .t

" Too much haze to get cloud point.

The data of Table II illustrates the light deasphalted oils as represented by deasphalted oils A and B fail to improve pour point. The data also demonstrates the necessity of about 1.0% of the additive to obtain any significant reduction in pour or cloud point. Lastly, the data shows that the heavier deasphalted oils C and D are more efifective than the lighter extract oils.

Example 11 The ASTM color of the No. 2 fuel containing 1.0% of deasphalted extract oil C of Example I was taken at the time of incorporation and again after a 7-month period. For comparison, the ASTM color of the original No. 2 fuel (without additive) was taken at the beginning and end of the same period. The results were as follows:

A ST M C olor Orig nal Alter 7 Months No. 2 Fuel (no additive) 1 3. No. 2 Fuel plus 1% deasphalted oil (1. 2 3

The data shows that the deasphalted extract oil additive of the invention possesses color stabilizing characteristics.

2. A fuel composition of claim 1 wherein the extract is obtained from a petroleum residual having an API gravity of about 8 to 14, a Conradson carbon content of about 7 to 12 weight percent, and a viscosity SUS at 210 F. of about 1600 to 2200.

References Cited by the Examiner UNITED STATES PATENTS 2,339,898 1/1944 White et al. 20819 2,664,338 12/1953 Winterhalter 208-15 2,725,345 11/1955 Binovic et al. 208l9 FOREIGN PATENTS 178,627 3/1962 Sweden.

DANIEL E. WY MAN, Primary Examiner.

P. E. KONOPKA, Assistant Examiner.

Claims (1)

1. A FUEL COMPOSITION OF IMPROVED POUR AND CLOUD POINT CONSISTING ESSENTIALLY OF A DISTILLATE HYDROCARBON FUEL BOILING ABOVE THE GASOLINE RANGE HAVING INCORPORATED THEREIN ABOUT 0.75 TO 1.25 VOLUME PERCENT IN THE RANGE OF ABOUT 750* TO 1050*F. AT 40% OVERHEAD AND HAVING A VISCOSITY AT 210*F. OF AT LEAST ABOUT 200*F. OBTAINED BY EXTRACTION FROM A MID-CONTINENT PETROLEUM RESIDUAL BOILING ABOVE ABOUT 750*F. WITH A PARAFFINIC HYDROCARBON SOLVENT OF 3 TO 5 CARBON ATOMS.