US2882219A - Recovery of cracking feed and asphalt - Google Patents

Description

April 14, 1959 P. H. JOHNSON RECOVERY 0E CRACKING FEED AND ASPHALT Filed April 26. 1954 2 Sheets-Sheet 1 Filed April 26, 1954 2 Sheets-Sheet 2 INVENTOR. P H JOHNSON ''r AT TORN EYS Genau o mesmo United States Patent RECOVERY F CRACKING FEED AND ASPHALT Paul H. Johnson, Bartlesville, Okla., assigner to Phillips Petroleum Company, a corporation of Delaware Applicah'on April 26, 1954, Serial No. 425,457

6 Claims. (Cl. 208-86) This invention relates to the fractionation of petroleum products. In one aspect, it relates to the production, in high yields, of a feed stock for a cracking process. In another aspect, it relates to the production of asphalt.

Recent developments in petroleum refining have made desirable the production of the maximum amount of catalytic cracking feed from a given volume of crude oil. Among the methods suggested for accomplishing such production is deeper or more extensive distillation of crude to increase the amount of heavy distillate recovered. Av diiculty inherent in this method is that there is a limit to the depth of distillation which can be used to produce a suitable feed for a catalytic cracking process. This limit arises from the fact that, as the distillation is extended to higher temperatures to recover heavier distillate fractions, these fractions become contaminated with metal compounds and with aromatic, resinous or asphaltic compounds present in the crude. The metal compounds, when present in a feed to a cracking process, poison the cracking catalyst. The heavy aromatic, resinous and/or asphaltic compounds, when subjected to cracking, excessively deposit carbon upon the catalyst.

I have found that solvent fractionation is a very desirable method for recovering maximum yields of cracking stock from reduced crude oils. The solvent fractionation process is Well known in the art (see, for example, Bray et al., U. S. 2,081,473, 1937). It comprises contacting, countercurrently or in a batch or singlestage operation, a heavy oil with a liqueed light hydrocarbon at an elevated temperature and pressure. The light hydrocarbon dissolves parainic materials and rejects heavy aromatic or asphaltic materials which are undesired as constituents of a feed for a cracking process. In addition, the light hydrocarbon rejects the metal compounds and the heavy aromatic, resinous and/or asphaltic compounds, as well as sulfur and nitrogen compounds, all of which are undesirable as constituents of a cracking feed. Compounds of metals, or sulfur, and of nitrogen are not undesirable as constituents of road asphalts.

In many refineries, there are available highly aromatic fractions which contain non-aromatic materials. Many of these fractions are sold as fuel oil at low prices. They ordinarily have a boiling point of at least 400 F.

I have found that such aromatic fractions which are free of asphaltenes contain materials which are valuable as feed to a cracking process and could be used as such if a method were available for separating them from the aromatic materials with which they exist in admixture.

2 Distillation, however, is substantially ineffective for such a separation.

Among these aromatic fractions are extract fractions obtained by the solvent extraction of materials such as lubricating oil fractions, cracked gas oils, and the like, and heavy fractions recovered during the fractionation of euents from a catalytic cracking process.

The extract fractions are obtained by contacting an oil of the type described with a solvent which selectively dissolves the relatively nonparaflinic constituents and subsequently separating the dissolved materials from the solvent. Such Aprocesses and solvents are well known in the art. Among these solvents are phenol, furfural, liquid sulfur dioxide, and glycol ethers.

Among the fractions recovered from a catalytic cracking process is a type of oil, known as decant oil or synthetic tower bottoms. This fraction is higher-boiling than the recycle gas oil fraction and ordinarily boils in the range of about 700 to 900 F. but sometimes has a boiling range as broad as 650 to 950 F. or even as broad as 600 to 1000 F. It contains relatively paraflinic constituents, which are valuable as feed lfor cracking, and condensed-ring cyclic or aromatic compounds which are undesirable as cracking stock but are very beneficial as asphalt constituents.

I have also found that solvent fractionation of asphaltene-free aromatic fractions of the type previously described herein, including decant oil, is not feasible, when such fractions are treated alone, because of the relatively low boiling range and the substantial absence of an asphaltene fraction.

I have further found, and my invention is based on this finding, that if an aromatic fraction of the type described is blended with a reduced crude oil and the mixture is subjected to solvent fractionation in the presence of a light hydrocarbon solvent, the following highly important and advantageous results are obtained, namely: (l) maximum recovery of the more highly paranic constituents of the'reduced crude and of similar constituents of the aromatic fraction; (2) the recovered paralinic constituents are substantially free of metal compounds and carbon depositing materials; (3) the cyclic or aromatic constituents of the aromatic fraction are recovered with the asphalt fraction, of which they are desirable constituents; and (4) when the solvent fractionation is conducted in combination with a fluid catalytic cracking process, a minimum production of residual fuel oil is obtained.

Thus, according to this invention, a reduced crude oil is blended with an aromatic fraction of the type described, and the blend is subjected to solvent fractionation in the presence of a light hydrocarbon to produce a cracking feed and an asphalt fraction.

The volume ratio of reduced crude to aromatic fraction is ordinarily in the range 3:1 to 10:1, although much higher proportions of reduced crude can be used.

The light hydrocarbon is ordinarily a paraffin containing from l to 5 carbon atoms per molecule. Methane, ethane, propane, isobutane, n-butane, isopentane, and npentane can be used. I ordinarily prefer propane or iso butane. In many instances isobutane is preferred.4 because of its higher solvent power for the paraflinic materials. Olelins within the C2 to C5 range can be used if desired. Methane and ethane, when used according -3 to this invention, are ordinarily used in admixture with one or more of the heavier hydrocarbons named, e.g. propane or butane.

The solvent fractionation can be conducted as a singlestage contacting but is preferably conducted in a multistage tower in which the light hydrocarbon ows countercurrently with respect to the oil charge. The oil charge, i.e. the blend, enters the tower at an intermediate level, and the isobutane or other light hydrocarbon enters near the bottom. An isobutane-rich phase is withdrawn from the top ofthe tower, -and an asphaltrich phase is withdrawn from the bottom. Isobutane is recovered from each phase 'and' recycled. n l The-fractionation `temperature depends on the "particular hydrocarbon solvent used vand on the composition ofdvthe pil treated. Generally, therange-is from about 75 to 400 F. A temperature .gradient .is preferably kmaintained in -the tower `to obtain :a rectification effect. Since the solvent power of the Alight hydrocarbon is a direct function of the density of the hydrocarbon, the-trop of `thetower is .maintained at a fhigher temperature than the bottom. When propane is the solvent, the bottom temperature is prefera- `blyin the range 1 05 to-205 E. and the .top temperature is preferably within the range -120 to 22.75 F. `depending on the kproperties of the oil charged. e When yisobutane is the solvent,- the top temperature vis preferably inthe range 2h00 to 290 F., 'depending on theproperties of the oil charged, and the bottom of the tower is maintained a't a lowervtemperature Ipreferably withinA the range 180 to 275 F. Ordinarily, ther bottom of the Atower is maintained at a temperature l to15 degrees lower than the top. However, alargeror smaller gradient `can be utilized. The speciiic temperatures to be used in any particular instance can readily be determined by one skilled inlthe art from this disclosure.

The fractionation pressure is atleast suticient pressure to maintain the light hydrocarbon solvent substantially in the liquid phase, or in the dense phase when the temperature is above the critical'temperature of the solvent.

The solvent-to-oil volume ratio is generally in the range 3:1 to 15:1, preferably 4:1 to 10:1.

The solvent density can be adjusted as desired by using a mixed solventcomprising twoor more of the light hydrocarbons herein disclosed, e.g. a mixture of ethane and propane, or a mixture of propane, isobutane, andl n-butane. I

Y.Embodiments of Ythis vinvention are lillustrated .in the drawings.

n, Figure 1 isv-a11ow `'diagram.illustrating the practice of this-invention in combination withaud catalytic cracking unit. e e v V'Figure A2 illustrates *results obtainable kby the practice .of this invention and is discussedinEXample 2 hereof.

As illustrated Vin Figure 1, areduced crude oil, i.e. one

Lfrom which materials boiling below '700 F. have been removed, enters ash zone 3 through inlet l2. Flash zone 3 is ordinarily operated under Vacuum, e.g. from 5 to 50 mm. Hg absolute pressure, and at a` temperature from 650 fto 750 F. to obtaina-ash distillate free of metal-compounds and carbon-depositing compounds. The distillate ispassed through conduits =4 and 13 to `preheat zone 19. AA Ystraight-run gas oil, e.g. of boiling range 400 to 700 F., can be added through inlet 4A. e

The residue passes through conduit 5 to fractionation yzone 6, being cooled to a temperaturein therange 125 to .160." F. incooler 5A. `Itismixed with, for-example, one-seventh of its volume of decant oil from-conduit 57. Themixture enters Ufractionation zone-6 at an intermediate level, e.g. at the middle thereof.

4Light:hydrocarbon entersfractionation zone 6, near the bottom thereof, being drawn v`fromlstorage 7 through con- JduitS. As stated, 'isbutane 'isoftenthe preferred sol- `vent;`howeverpropane is satisfactory and is often used on accounti'of availability in `large quantities at manyren- Fractionation zone 6 is ordinarily a vertical column of a type known in the art. lThe liquid propane enters the lower part of the column and rises therethrough in countercurrent dow with respect to the oil blend. A propanerich, or extract phase is withdrawn through conduit 9 and passed to flash zone 10 wherein propane is flashed. Propane is recovered through conduit 11, condensed in condenser 12, and recycled to storage 7.

The residue of the flashing in zone 10 is a clean, metalfree, low carbon residue, parainic oil suitable as cracking stock. This oil is mixed with the oil in line 4 and passed to preheat zone 19 wherein the mixed oil is vaporized and preheated to a cracking temperature, e.g. 900 F. It can be diluted with steam ifsdesired.

` A fluidized cracking catalyst, such as silica-alumina, or silicaealumina-'zirconia 'is added 1through line 33 from 4storage 31. The catalyst-oilmixture ows .throughconduit LZQ kto f cracking Izone 21, which .can Ybea crackin g reactor of kany type 'known in the art. VThe oil vapor flows upwardly 'through fa dense, fluidiz'ed lbe'd `-of `-catalyst and is converted to lowerboiling products. Most of the catalyst remains in zone `21. Small amounts of catalyst nes suspended in the product are separated in separator 23 and passed through conduit 24 to regeneration zone 27. Part of the catalyst is withdrawnfrom zone21 through conduit 25 and passed to regeneration zone 27, a suitable carrier gas `being added through'in'let 26. lThe withdrawn catalyst is maintained as a dense, fluidizedlbed in zone 27 and is contacted with a regeneration gas, such as steam 'and/or air, which is supplied at a hightemperature, e.g. 1000 `F. 'through inlet '28. Resulting 4iluegas is withdrawn through outlet 29. Regenerated 'catalystis returned 'tostorage 31, carrier gas being supplied through inlet 30A and withdrawn 'through outlet 31A. Fresh catalyst is added, as needed, through inlet 32.

"Cracked product is'passed through 'conduit 34 Vto separation zone 35, which is ordinarily a fractional distillation unit. A "gas and gasoline 'fraction is recovered through conduit 36 and Vpassedto separation zone 37 'for separation of a 'gasoline fraction, withdrawn-through outlet 39, 'and `a gas fraction, withdrawn through 'outlet 38. e A gas oil fraction (40G-'700 F.) is recovered in zone 35 and passed through line 40 to separationzone 41, from which alight fraction is withdrawn as furnace oil 'through outlet 42.

A heavy cracked fraction, which contains 'any catalyst nes remaining in vthep'roduct, is 'recoveredthrough line S3 and passed to solids removal zone 54,which comprises 'known equipment'such as "a l"settler, classifier,"thickener, or `filter, or :any combination df "these LPart Mof .the oil'is 'preferably-returned; through conduits SSAa'nd 55,"t'o zone 35 at t a `level :therein above "the level of entry fof vmaterial 'from line 34. The'returned material' scrubscatalyst fines from upflowingvapor.

Solidsffree -oil,'knownas"decant oil iswithdrawn'from zone 54 lthrough line V55. APart can'be returned to zone 35, as described. Catalyst-oil slurry is withdrawn through outlet'56.

The decant voil is passed throughonduit 57 `to fractionation .zone 6, aspreviously describedherein.

.From -fractionation zone rf6, arainate fractionis removed through conduit l14 and passed to flash zone '15, -vwherein the dissolved propane is ashed oif. aThetpropane is passed through conduit 16 to storage 7,being condensed in condenser 17.

'An asphalt product,containing-Iasphaltic constituents of fthe 'crude fand the heavy polycyclic constituents of the or liquid sulfur dioxide, vsupplied through inlet 52. The raiiinate phase, comprising mainlyparaflinc materials is recycled through conduit 4S, preferably after removal of dissolved solvent by means not shown. The extract phase is passed to stripping zone 47 through conduit 46. Solvent-free extract, comprising cyclic materials and some paratiinic materials is recovered through conduit 48 and cooler 49 and passed to fractionation zone 6 along with the decant oil. Stripped solvent is recycled through conduit 50. cooler 51, and conduit 52.

Those skilled in the art will recognize that the apparatus diagrammatically shown in Figure 1 is conventional apparatus and that other apparatus can be used. Thus xed-bed, moving-bed, or suspensoid cracking can be used in place of the iluid catalytic cracking unit shown.

Figure 2 is a diagrammatic oil material balance showing results obtainable according to this invention. Flow of isobutane is not shown, but is as described in connection with Figure 1.

A West-Kansas vacuum reduced crude is blended with Y rainate. The 13.3 volumes recovered Vin the extract has,I

a correlation index of 64.8, indicating a decidedly lower aromatic content than that of the original decant oil. The correlation index of the total extract is 47, indicating high paraiiinicity and therefore desirability as a cracking stock.

The asphalt (rainate) properties shown in Figure 2 show that the asphalt is satisfactory for a blending stock for the production of road asphalt. Ordinarily an asphalt having the properties shown is blended with a softening or solvent material to produce va paving composition.

The softening point is determined by the ring-and-ball method. The penetration value is determined by ASTM method D5-49, a 100-gram weight being used. The oliensis test is a spot test described in Highway Materials, Part II, Methods of Sampling and Testing, by the American Association of StateHighway Officials, page 157, Method T102-42. A negative oliensis test indicates the absence of unstable internal phase relationships. (See Abraham, Asphalte and Allied Substances, volume two, page 925, iifth edition, 1945, D. Van Nostrand Co., New York, N.Y.)

In other respects, Figure 2 is self-explanatory.

Example Il A vacuum-reducer, West-'Kansas crude oil was blended with a decant oil obtained in a uid catalytic cracking process, and the mixture was subjected to fractionation in the presence of liquid isobutane.

zThe vacuum-reduced crude amounted to 15.4 volume percent of the total crude and hadvthe following properties:

The deeantbil had a Bureau of Mines correlation A.

index of 81 and an A.P.I. gravity of 11.8.

ing properties:

Bureau of Mineslcorrelation index 47.6 Gravity, A.P.I 18.3 Ramsbottom carbon residue, wt. percent 3.3 S, wt. percent 0.79 N, wt. percent Fractional distillation of the isobutane-free extractv showed that, of the 74 volumes of said extract, 13.3 volumes were derived from the decant oil and 60.7 from th'e reduced crude. The vacuum distillation data (760 mm. Hg) for the decant oil, the total extract, and the extract derived from the decant oil were as follows:

Temperature, F. Corrected 0 mm. Hg

Vol. percent distilled Decant Total Extract Oil Extract from Decant 011 Without With Decant Deeant Oil Oil Sp. gr l1. 0850 1. 0 8 softening point, F 1 280 75 Peligtration, 115 F., 100 gm. Weight, 5 sec. in cm./

Yield, volumes/100 vol. reduced crude 39. 3 41. 3

1 Interpolated from experimentally determined curves showing asphalt properties plotted against asphalt yield (with no decant oil added) from the same crude oil charge.

The foregoing data show that the blend of decant oil, accordln'g to this invention, when fractionated, yields an increased volume of good-quality cracking feed and an increased volume of asphalt having properties making it satisfactory as a paving material component.

Example III ,The blend ofreduced crude and decant oil described 1n Example II (115.3 volumes, total) was fractionated '7 byfcontactn-'g wthliquid-isobutane at .a top tower-'atemperature of 252 F., a bottom tower temperature of 237 .F.,.=a pressure of 565 ;p.s.i. =`and :.a Ivolume ratio of isobutaneto blendiof r6.7: 1

`Volumes'fandpmperties--zof .feed :and lprodnct .materials are as follows:

8 `:recording :to this invention. -Insuch a case, a higher `yield aof cracking V.stock -(fextract) :and a lower yield of `asphalt (rainate) vare obtained. The increased yield of kcracking stock is accompanied by a decreased selectivity of separation. Thus, Aa 4:greater ,proportion of the u ndesired materials, such as metal .compounds and `carbon Extract Asphalt .Reduced .Decent Total Extract from Asphalt Obtained Crude Oil Extract from Decent from from Crude (104 free) l fCrude #Oil .Blend wltbout Decent .Q11

Volumes 51. 9 50. 4 "Gravity, -A.P.I softening Point, F-- 22D 1i228 -Bnr..-Mines,Corr..Inde I lene'trationy 77/100/5, iam/1100--; :Bainsbcttom Carbon Residua .i wt.Bement--.--- 'S,'Wt.jPercent .-7 Nwt.EEercenty v .sp..gr 1.0?32` '1 Loses Tenetration, 115/100/5, cmJlO l0 l l2 Distillstion A(5 mm), Percent Distilled:

IBP 520 625 542 629 713 513 In 662. 790 549 .20 713 908 698 "in 747 975 730 n 77() 1, 015 755 50 796 1, O50 777 -60.... '818 1, 075 799 70--.. 836 821 80 V869 850 90..-. 919 902 1 Interpolated from experimentally determned'curves 'showing asphalt:v properties plotted ngainst'aspbalt yield (with no decant oil added) from the same crude oll charge.

" The 'data showithe production of good-quality cracking stock and asphalt according to this invention. The data falso ishow that a further reduction, as compared with eEXample II, of the carbon residue, the sulfur content, and the nitrogen Ycontent :of -the cracking :stock can be obtained by fractionationathigher temperatures.

Example I V V`example shows yields .obtainable by propane `,fractionaiion of a crude residuum obtained by vacuum viiashing as compared with yields obtainable by isobutane fractionation. The residuum fraction was 14.6 volume percent of the vtotal crude. The-dataA are as follows:

Solvent-In- Top Tower soluble Residue Solvent Temperature, (Railinate),

F. Vol. Percent of Total Crude Propane -175 10. 82 Propane 118 :8. 9 .lsobutane---.. 250 7.9 'Isobutane 2(15`- k6.12

Theldata show that isobutane *has a .greater solvent 'powerthan doesjprop'ane `at fa giventemperature 'The amount of .'rallinate increases llas' temperature `increases. "Therefore, 'at '205 F.,the amount 'of raliinateproduccd by propane wouldbe higher thanl0.82.

As indicated in Figure l, itis often desirable to remove from the crude, materials boiling below about 1000 F. However, .a crude residuum containing materials (gasoil) Aboiling 'as lovvjasV 'ZOO-i800 canbe.solventfractionated 'formera accompanies 'the increased yield of cracking stock. For this reason, it -is often preferred to operate as dcscribed 4inconnectionwith Figure 1.

Example lV Six runs lwere conducted to compare isobutane :fractionation ,of a predominantly parainic crude residuum alone withisobutane fractionation of a mixture compris- Ving 86.7 :volume percent of the sameresiduum and 13:3 -volume percent offafdecant oil fobtained, as previously described, from .a uid .catalytic ,cracking process. The lresiduum was obtained from a Western Kansas crude by noncracking vacuum distillation and `amounted to 15.4 volume percent-of ``the1total crude. ,It had an API gravity of 10.3, an initial boiling point of 923 F., a 5 percent distilled point of 982 F., and la l0 percent distilled point of l004 F., all of these temperatures being corrected to atmospheric pressure The decant o il had an API gravity of "11.8, a Bureau-ofMines correlation index of A81, and distillation characteristics as follows:

The .data ,obtained in the six runs are .shown .inthe following table.

Without Decent 011 With Decent O11 Run No 1 2 3 4 5 6 lOl/Oil, liquid volume ratio 3. 1 12. 4 7.0 3- 2 9 8 4-9 Top Tower Temp, F 225 205 206 224 205 206 Bottom Tower Temp., F 212 191 191 211 192 190 Pressure, p.s.i 500 450 450 450 500 513 Asphalt yield, vol. percent o 6. 7 6. 0 6. 2 6. 2 6. 0 5. 9 Asphalt Properties:

Penetration, mm., 5 sec., 100 gm.

weight- 150 F 11.5 9.5 8.0 7.8 6.3 4.5 130 F. 6. 0 5.0 4.0 3. 6 3. 5 2. 5 115 F- 3. 0 2. 5 2. 0 1.9 1.9 1.7 77 F 0 0 0 0 0 0 Sp. Gr., 60 F 1.0816 1.0850 1.0818 0.0900 1.0923 1.0901 Softening Point, ring and ball, 272 280 283 257 285 296 h-soluble, wt. percent, 77 F-.. 99. 91

The foregoing data, which were obtained under comparable process conditions, show that asphalt of superior penetration characteristics is obtained by the process of this invention (runs 4-6).

In the foregoing examples, the fractionation tower was 3 inches in internal diameter and 25 feet in height. n It contained staggered horizontal bales spaced 2 inches apart. Each baille covered one-half of the cross-sectional area of the tower. The tower was rated at from 3.5 to 4.0 theoretical stages of contacting.

Variation and modification are possible within the scope of the disclosure and claims to this invention. The essence of the invention is a process comprising blending an aromatic, asphaltene-free oil with a heavy petroleum residuum fraction, subjecting the blend to solvent fractionation in the presence of a low-boiling hydrocarbon, and recovering an extract and a ranate. While certain structures, examples, and process steps have been described for purposes of illustration, the invention is clearly not limited thereto.

I claim:

1. A process which comprises blending together a reduced crude oil with a substantially asphaltene-free, aromatic-containing hydrocarbon extract having an initial boiling point of at least 400 F. and obtained by extraction of an aromatic-containing oil with a solvent which selectively dissolves aromatic hydrocarbons, contacting the resulting blend with a liquid hydrocarbon having not more than carbon atoms per molecule, and recovering an extract comprising a hydrocarbon material suitable as a catalytic cracking feed and a ranate comprising an asphalt.

2. A process which comprises blending together from 3 to 10 volumes of a reduced crude oil having an initial boiling point of at least 700 F. with one volume of a substantially asphaltene-free, aromaticcontaining hydrocarbon extract having an initial boiling point of at least 400 F. and obtained by extraction of an aromatic-containing oil with a solvent which selectively dissolves aromatic hydrocarbons, contacting the resulting blend with a liquid hydrocarbon having not more than 5 carbon atoms per molecule, said contacting being conducted at a temperature in the range 75 to 400 F., recovering an extract comprising a hydrocarbon material suitable as a catalytic cracking feed, and recovering a raliinate comprising an asphalt.

3. A process according to claim 2 wherein said liquid contacting hydrocarbon is propane and said contacting is conducted in a zone having a top zone temperature in the range of 120 to 225 F. and a bottom zone temperature lower than said top zone temperature and in the range of 105 to 205 F.

4. A process according to claim 2 wherein said liquid contacting hydrocarbon is isobutane and said contacting is conducted in a zone having top zone temperature in the range of 200 to 290 F. and a bottom zone temperature from 10 to 15 degrees lower than said top zone temperature.

5. A process which comprises vacuum ilashing a crude petroleum fraction having an initial boiling point of at least 700 F., said flashing being conducted at a temperature in the range 650 to 750 F. and an absolute pressure in the range 5 to 50 mm. Hg; recovering a distillate and a residue; blending said residue with a cracked fraction subsequently described, in a ratio in the range from 3 to 10 volumes of said residue per volume of said cracked fraction; passing the resulting blend to an intermediate level in a contacting zone; countercurrently contacting said blend in said zone with a liquid phase of propane; maintaining the top of said zone at a temperature in the range 120 to 225 F. and the bottom of said zone at a lower temperature in the range to 205 F.; removing an extract phase from the top of said zone and a railinate from the bottom of said zone; removing said propane from said extract phase; catalytically cracking the extract thus recovered in the presence of a nely divided, iluidized cracking catalyst under cracking conditions of temperature and pressure; fractionating a cracked product and recovering a gas fraction, a gasoline fraction, a gas oil fraction, and a heavier fraction which boils in the range 700 to 900 F.; extracting said gas oil fraction with a solvent which selectively dissolves aromatic hydrocarbons therefrom, recovering a hydrocarbon extract from the last-mentioned extraction step; mixing the last-mentioned extract with said heavier fraction to form said cracked fraction; blending said cracked fraction with said residue as aforesaid; and recovering an asphalt fraction from said railinate phase.

6. A process which comprises vacuum flashing a crude petroleum fraction having an initial boiling point of at least 700 F., recovering a distillate and a residue; blending said residue with a cracked fraction subsequently described, in a ratio in the range from 3 to 10 volumes of said residue per volume of said cracked fraction; passing the resulting blend to an intermediate level in a contacting zone; countercurrently contacting said blend in said zone with a liquid phase of hydrocarbon having not more than 5 carbon atoms per molecule; removing an extract phase from the top of said zone and a ralinate phase from the bottom of said zone; removing said hydrocarbon from said extract phase; catalytically cracking the extract thus recovered in the presence of a cracking catalyst under cracking conditions of temperature and pressure; fractionating a cracked product and recovering a gas fraction, a gasoline fraction, a gas oil fraction, and a heavier fraction which boils in the range 700 to 900 F.; extracting said gas oil fraction with a solvent which selectively dissolves aromatic hydrocarbons therefrom; recovering a hydrocarbon extract from the last-mentioned extraction step; mixing the last-mentioned extract with said heavier fraction to form said cracked fraction; blending said cracked fraction with said residue as aforesaid;

` l 112 and recovering an asphalt fraction from said ranate 2,203,930 Smith June 11, 1940 phase. 2,525,812 Lien et al. Oct. 17, 1950 2,538,220 Willauer Jan. 16, 1951 References Cited in the file of this patent 2,531,301 'Sayko et a1 June 15, 1954 UNITED STATES PATENTS 5 2,700,637 Knox 12111.25, 1955 2,051,776 Petty et a1 Aug. 1s, 1936 2727'853 Henmg Dec' 20 1955 2,079,886 Voorhees May 11, 1937

Claims (1)

1. A PROCESS WHICH COMPRISES BLENDING TOGETHER A REDUCED CRUDE OIL WITH A SUBSTANTIALLY ASPHALTENE-FREE, AROMATIC-CONTAINING HYDROCARBON EXTRACT HAVING AN INITIAL BOILING POINT OF AT LEAST 400* F. AND OBTAINED BY EXTRACTTION OF AN AROMATIC-CONTAINING OIL WITH A SOLVENT WHICH SELECTIVELY DISSOLVES AROMATIC HYDROCARBONS, CONTACTING THE RESULTING BLEND WITH A LIUQUID HYDROCARBON HAVING NOT MORE THAN 5 CARBON ATOMS PER MOLECULE, AND RECOVERING AN EXTRACT COMPRISING A HYDROCARBON MATERIAL SUITABLE AS A CATALYTIC CRACKING FEED AND A RAFFINATE COMPRISING AN ASPHALT.

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