US 2358128 A
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G. R. LAKE LUBRICATING `OIL PRODUCTION sept. 12, 1944.A
Filed April 29. 1941 UNS. Nk. WN
Patented Sept. 1.2,' 1944 LUBRICATING `OIL PRODUCTION K George ItfLake, Long Beach, Calif., assigner vto,
Union Oil Company of California, Los Angeles, A
Calif., a corporation of California y Y 4 i Applicaton April 29,1941, Serial No. 390,943
22 claims( (c1. gigs-'71) 'Ihis invention relates to the separation `of relatively paraflinic from relatively non-paraffinic roil fractions in the lubricating oil range. The invention relates particularly tothe produc.- tion of lubricatingoils having a relatively low .viscosity gravity constant from lubricating oils containing oil fractions having a relatively high Y viscosity gravity constant.`
An object of the present invention is to projduce lubricating oil having a relatively low viscosity gravity constant by vazeotropic,,distillation. Another object is'to remove by-azeotropic distillationsuch oil fractions as exhibit low parainicity or high viscosity gravity constant which have poor lubricating oil `qualities from a lubricating oil fraction containing the same.
A further object is to separate asphalt, resins and resin-like materials from oils containing the same by azeotropic distillation.
A further object is to produce good quality f lubricating oils in a more Yeconomical manner without necessarily resorting to extraction with selectiveA solvents.
It is well known to produce lubricating oil of relatively low viscosity'gravity constant or parainicity, by subjecting the lubricating'oil fraction, such as petroleum distillates, to extraction with a selective solvent adapted to separate relatively para'inic oil fractions Yfrom relatively non-parainic oil fractions. In this proces`s,"thel` selective solvent, as for example phenol, is mixed with the lubricating oil fraction which preferentially discloses the f relatively non-paranic oil fractions, th'us permitting by stratification or settling, the separation of the relatively parafnic oil fractions from the solution of selective solvent and relatively non-parainic oil fractions. The viscosity gravity constant has been dened by Hill and Coates in the Journal of Industrial and Engineering Chemistry in'vol. 20 1928, page 641. parainicity or naphthenicity of an oil. vA low value represents a high degree of yparaffnicity.
while a high value indicates ,a high degree Vof naphthenicity. The viscosity index (V. NI) is also a measure of the paranicity of an oil, a high V. I. indivating a goodquality parainic type oil and a low V. I. indicating a poor quality nonparainic type oil. It is also well known to separate asphalt, resins and other asphaltic andresin-like materials from oils by means of solvents which preferentially A dissolve the oil fraction-andprecipitate the asphalt and the like materials from the solution of solvent and oil. The amountF of precipitate y will, of course, depend upon thecharacter of the solvent; its gravity and-thetemperature' of treat'- ment or separation. For this purpose many sols vents such as the liquefied normally gaseous hy- 5 f drocarbons, such as propane, etc., and Anormally liquid hydrocarbons, such as naphtha,r hexane, etc.; have been used.
1 have discovered that the foregoingreiativay l non-parainic components, such as the' asphalt,
v resins Vand aromatic or naphthenic oil fractions i may berremoved from oils by-a'fractional dis,-
tillation process knownas azeotropic distillation wherein a substance is addedto the mixture to be distilled which Will'vform'fan azeotrope boili l5`in`g at a lower temperature with` one or` more ofv the components in the oil so as to permit separation from the other components. I have found that lubricating il of relativelyv low viscosity gravity constant may be produced by` subjecting the lubricatingfstock containing the high viscosity gravity constant'fractions to fractional distillation .in the presence of anI added substance, lhereinafter referred to asvan azeotropeformer,
which is adapted to form `an azeotrope `or lowerf v boiling mixturev with the lubricating oil frac-y tions of relatively high paraicinity so Ythat these components may be distilled' from ythe relatively f *lowf parai'fmicity Voil fractions of'sub'stantially .the
same boiling point range as the high paraflnioity 3Q lubricating oil fractions. Ordinarily, theseparation of lubricating oil stocks yinto relatively low and relatveiyhigh viscosity 'gravity constant oil fractions is diicult if not'impossiblefb'y VtheV usual-fractional distillation process in the absence of a material, which alters `"the, distillation 'Y l`temperature of one of the'fractions in the mixture.
of one class of components sofas to permit the Y 4b desired separation. This constant Vrepresents the Y While the separation of asphalt from oils offers less dimculty by ordinaryV fractional distillationn in viewof the fact that thev asphalt is generallyr of a higher boiling point thanthe lubricating orV other oil components, nevertheless, a consider- ,able quantity of asphalt has been found to-be present in even such lightllubricatinaoildistillates -as the S. nA. EL 420 oil fractions This is.
particularly true of the lighter or pseudo asphalt or resin-like ma'terialsuwhich boil Vcloser to-` the. oil fractions and distillv over therewith. lI haveV found that the Ydistillation in thepresence of an azeotrope former .lowers the Vdistillation .temperature of the Voil components softhatrthere is less tendency for the asphalt and. likecompo-f However, the distillation yin' thepresen'ce ,of an azeotrope former lowers the boiling p'oint nents to be distilled together with the oil components. The azeotropic distillation may distill the more paraifinic oil fractions leaving asphalt and the less parainic oil fractions as still bottoms.
In generaL'when choosing azeotrope formers,
for separating the non-paraflinic components from lubricating oil fractions, it is preferable to employ an azeotrope former having substantially the same boiling point as the stock, and, preferably, boiling not more than about 100 F. below or about 40 F. above the boiling point of the stock. As azeotrope formers which Ihave lfound useful for treating lubricating oil fractions of various grades are the poly glycols, such as tri, tetra, heXa-, and nona-ethylene glycols, di,
, tri, and tetra-propylene glycols, mono, di-k, and
etc; high boilingfamines, such asv tri-ethanolamine, isof-propanolamine,` tri-ethylene tetra-Y mine, tetra-ethylene pentamine, tri-ethylene tri-- yIn carrying out the process, 4the lubricating oil stock, suchy as crude oil distillate having a boiling range .such that when the stock is treated to remove undesirable components, it will finish into a lubricating oil of the desired-grade or which may be `blended withv other lubricating-'oils to produce theoil of desiredgrade, is subjected to fractional distillation in the presence of the azeotropeformer until `all of the paraffin-type oils have been distilledv from the mixture. T-hese components whichV arevaporized are condensed-together with the azeotrope former.v In order to VSeparate'the azeotrope former vfrompthe oil. components; itis merely necessary' tocoolV and/or mix the condensate mixtureiwithv Water Whichidissolves in the azeotrope former and allowslthe hydrocarlbons to separate from the aqueous azeotrope former.' By allowing this mixture to settle, two distinct layers are formedyan upper layer consisting of the hydrocarbon and fa lower layer of the diluted azeotrope former. These maybe sQeparated from each other'by simple decantation.
Depending Vupon the conditions and l control during the azeotropic distillation, the overhead from the distillation maycontain not only al1 ofA the` paraffin hydrocarbons but also the olefin type and naphthene type hydrocarbons, leaving as undistilled bottoms only the'more aromatic Y type hydrocarbons. If desired, theoverhead materialmay be redistilled in the presence of the same or different azeotropeiformer under controlled conditions'to separate theV paraffin from the other olen and/or naphthene'type hydrocarbons. If` the lubricating oil`stock had not previously been dewaxed, th'e wax components Ywill beY contained in the overhead parainic oil fractions whichrmay then be subjected' to conventional methods of dewaxing; such asby diluting with a diluent and chillingand' filteringz the` ever, in such cases where the oil fraction has a very Wide boiling range such that all of the paraflnic type oils cannot be separated in one step by azeotropic distillation, the lubricating oil stock may be fractionated into a plurality yof cuts, each having a boiling range such that the azeotropic distillation will permit all of the high parafnicity components to be removed from the low parainicity components. The separated high parafnicity components may then be reblended in any desired proportion to produce the proper lubricating oil.
If desired, the wide boiling range lubricating oil fraction may be separated into low and high .parainicity oils. by the following procedure.
t When the azeotrope former is added to the oil fraction, an azeotrope is'formed with the parafnic hydrocarbons thus lowering their boiling points.` The boiling point range of the azeotrope, however, ranges below and within the lower portion of the boiling range of the low parairlnicity fractions. By partially distilling this mixture, the first component which will distill over will be the lighter portion of the relatively high parafnic hydrocarbons admixed with azeotrope former. Further distillation willremove a mixture of azeotrope former, the higher boiling portion of the relatively high paraflinic hydrocarbons and the lower boiling portion of thetrelatively low parai'linic oil fractions, leaving the higher boiling portion of the relatively low parafflnic oil fractions as still bottoms. By removing the azeotrope former from the middle fraction and fractionally distilling, the resulting oil mayl be separated into an overhead fraction consisting of the lighter portion of the less parainic oil fractions and a bottoms fraction of the higher boiling portion of the more paraiinic oil fractions. The parafiinic oil fractions may be combined to produce a lubricating oil having the same boiling range as the original stock.
In some cases, Ait may be desirable to Yseparate a portion of the higher parafnicity oil fractions `using one azeotrope former, then removing the 5 azeotrope former from the remaining undistilled I oil Vand then continuing the distillation in the presence of another azeotrope former to remove the remaining oil fractions Yof high parainicity.
Thisprocedurermay be carried out in as many azeotropeformers for each stage'as may be necessary to recover the desired oil fractions. In such cases, it is desirable to employ progressively higher boiling azeotrope formers in order to cor-l respond With the boiling point of the fraction to kbe distilled. Y Y Y Other objects, features `and vadvantages of my invention will be apparent -to those skilled in the art from the following'description of `theiinvention'which representsa diagrammatic arrangement `of apparatus for carrying out my invention. In the drawing, the hydrocarbon feed to be resolved into relatively low and relatively high viscosity lubricating oils, such as for example a wax-containing lubricating oil distillate which finished up `into an S.V A'. E. 20 lubricating oil I derivedfrom a SantaFe, Springs crude oil, is
taken from'tank I0 viay line I I controlled by valve y I2 and pumped byv pump I4 into line I5. Azeotrope former, r'such'as tetraethylene glycol, is
taken from tank I'S via line-` I'I` controlled by valve I8 'and ispumped'by pump I8 through line 20 into line I5. This mixture in line I5 consisting of the hydrocarbon feed and azeotrope .for' mer in ratio of approximately one volume of 2| .where the mixture is subjected to'iractionation, heat lbeingsupplied by 4closed steam .coil
v22. Insome cases, it may be desirable to introduce/ the azeotrope former into theqtop of the.
column so as to provide reflux therein. In the Y iractionating column, the distillation is controlled so as to ldistill overhead an azeotrope consisting of the relatively low .viscosity gravity constant `lubricatingoil fractions together with Ytheazeotrope former. This fraction is removed from the fractionating column via line 23, condensed and cooled inv condenser 24 andtpassed via line 25 into a vseparator 26 where the hydrocarbons separate from the azeotrope former as two distinct layers which may be removed `from each-other by simple decantation. lIYhe lower layer consisting of azeotrope former is withdrawn via,line,21 controlled by valve 28 and is pumped by pump 29 to storage tank IB. Y.
:The upper layer in separator 26 may be passed tostorage. However, if this fraction contains azeotrope former, it is passedvia line 30 into the tions. admixed with relatively high viscosity gravityy constant oil fractions. The product 'ob-l tained as low kviscosity gravity constant lubrieating oil which is collectedin tank 40 will, therefore, consist Yof. the lower boilingv fractions of the low viscosity gravity constantoils.- )Thehigh boiling low viscosity gravity constant lubottom of kwasher 3| provided with packing ma-A teria1,such as broken Ytile 32, for effecting intimate countercurrent contact with water which is introduced into the washerfrom tank 33 via 7 ing operation is preferably carried out at .an
elevated temperature of approximately 300 F. Iunder superatmospheric pressure. The low visbricating oils contained in the bottoms of fractionatinglcolumnpZl may be retreated by azeotropic distillation yemploying a higher boilingV Y withdrawn from tank48 via line54 controlledV by valve 55 and pumped by pump 56 into line 53. The mixture then enters fractionatingcol-H umn -51 whereiti is subjectedjto fractionation, heat being supplied by closed steam coil 58.l In
the column, the distillation is controlled so asv to distill overhead an azetropeconsisting of` the relatively high boiling low viscosity gravity constant llubricating oils togetherfwiththe'azeof trope former'which is removed via line 59, condensed ,and eooled inv condenser'60` and passed via line 5| into separator'62 where the mixture separates into twov layers, i. e. a lowerlayercon sisting ofazeotrope v4formerfwhich is1 passed via line 63 controlled `by valve 54, pump 65 and line 66 into tank 49 andan upper layer of hydrocarbons which is passed via line'61 to washerf |58r providedwith packing 69 where it contacts waf ter introduced from tank,33 via lines 34 and cosity gravity constant oil in tank v40 may be Vclewaxed lby mixing the oil with a liqueed normally gaseous hydrocarbon under pressure, such as liquid propane, in the ratio of three volumes of propane to one of the oil 0r withY other diluents now known in this art. The solution of propane and waxy oil is chilled to a temperature high parainicity lubricating oil may be further treated with selective solvents, such phenol, in order to further purify the oil. If desired, instead of dewaxing the oil subsequent to the azeotropic distillation, the lubricating oil 'stock may be dewaxed before being subjected to azeotropicdistillation.
The lower phase in washer 3| consisting of dil'ut'e aqueous solution of azeotrope former is returned to tank 33Y vialine 4| controlled by valve 42 and pumped bypump 43. If desired, this solutionmay be distilled to recover azeotrope former which mayfbe Vreturned to' tank I6. V'Ihe undistilled bottoms in the fractionating column 2|l consistingeof the relatively nonparaftnic oil fractions is `removed via 'line 44 controlled by valve 45 and pumped' bypump 46l through line 41 into storage tank 48.
In some cases particularly where the lubrieatingY oi1 stock has a very wide boiling range,
equal quantities. The lighterfraction havingr aV 10 controlled by valve 1|. 'I'heoil fraction is: removed via line 12, cooled1infc`ooler 13 1andy passed to storage tank 14. This fraction mayY be mixed in any desired proportion with the oil and`pumped byY pump 8| through' line 82 Y into tank 83. If desired, depending upon wheth- `er this Voil contains still higher boiling relatively*-` low viscosity gravity constant oils, it may be i subjected tofurther azeotropic distillation in `the presence of a still higher boiling azeotrope former. Y f l .j As examples of my invention, the following is submittedfwhich is' merely illustrative thereof` and is not to be considered as limiting:
YA lubricating oil distillate obtained fromthe vacuum distillation of aSanta'FeSprings crude oil havinga gravity of 21.8 A. P. I., a viscosity o f 51'seconds (Saybolt Universal at 210 F.) and Va viscosity ,gravity constant `of 0.866 was fractionally` distilled into two cuts of substantially viscosity of 51 seconds, a gravity of 22.4 A. P. I. and a Viscosity gravity constant of 0.865 was subjected toAv fractional distillation inthe presence ofapproximately an equal volume of .tetraethylene glycol under relatively Ahighvacuum at an overhead temperature of about 275- F. which `grad-v ually increased to about 325 F. towards the end of the run. VThe overhead oil which kwas separatedrfrom the azeotrope former had a gravity of -28.7 ALP. I., 'a viscosity of 45.5 yseconds land a viscosity gravity `constant ol`-0.823-and was obtained ina yield `of 637% by volume. The distillation bottoms representing 37%Fhad agravity October 8, 1940;
of 7.9' A. P. 1., a viscosity of v142 seconds and a viscosity` gravity constant-of 0.968.
' The heavier fraction having a viscosity of60 `a viscosity of 57.7 seconds and a viscosity gravity constant. of- 0.821 and wasY obtained in a yield of 65% by volume. The distillation bottoms representing 35% had a gravity of 6.0 A. P. I., a viscosity of 305 seconds and a-viscosity gravity constant of 0.974.
The-overhead light and heavy fractions recovered-in the foregoing azeotropic distillations were blended. The blended material representing 64% by volume based upon the original 21.8 A. P. I. lubricating oil distillate had a gravity of 28.1 A. P. I., a viscosity of 51.5 seconds and aviscosity gravity constant of 0.821. The bot- `toms from each of the azeotropic distillations were blended and the blendshowed a gravity of 4'7.0, a viscosity of 224 vseconds and a viscosity gravity constant of 0.968'.
Another portion of the original 21.8 A.' P. I. lubricating oil distillate was-fractionally distilled in the presence of Vapproximately two volumes of tetraethylene glycol under relatively high vacuum at an loverhead temperature of 275 F. whichgradually increased to aboutv 350 F. towards the en d of the run. The overhead which Y was separated from the azeotrope former represented 48% by volume of the. feed andhad a gravity of 29.0 A. P. I.; a viscosity of 45 seconds and a viscosity gravity constant of 0.821. The distillation bottoms had a gravity of 15.4 A. P. I., a viscosity of 78 seconds and a viscosity gravity constant of 0.910.
It will be observed that in the'foregoing azeotropic distillations, substantially all of the parafilnic components were removed by thedistillation and separately recovered since in each of the azeotropic distillations towards the end of the run,l the overheadA product consisted substantially only of Yazeotrope former' eventhough the temperature of. distillation-was increased appreciably.
The foregoing description of my yinvention is merely illustrative and is not to bev considered as limiting as many variations can be made by those skilled in the artv Without departing from the scope of thev following claims.
aso-Suas nic 1ubricating oiliracticns from relatively nonparainic oil fractions which, comprises fractionally vdistilling an oil fraction containing a mixture Ofsaidrelatively parainic and relatively non-parainic oil'fractionsto produce a pluralityof fractions, distilling each of said oil fractions in the presence of an azeotrope former selectedV from the class consisting of polyglycols and derivatives of-polyglycols having a boiling point not more thanlabout 100 F. below or about 40 F. above the boiling point of the fraction undergoing distillation and capable of forming a lower boiling azeotrope with saidA relatively` parafiinic oil fractions and thereby separating said azeotrope fromv the' remaining relatively non-paraiiinic oil fractions, separating azeotrope former from said relatively paraiiinic oil fractions and blendingsaid separated relatively paranic oil fractions.
3. A process for separating relatively paraffinic oil fractions vfrom relatively non-parainic oil fractions which comprises fractionally dis-- tilling an oil fraction containing a mixture of said relatively parafinic and relatively nonparaflinic oil fractions in the presence of an azeotrope former selected from the class consisting of polyglycols and derivatives of polyglycols -and relatively non-parafiinic oil fractions andvfractionally distilling the remaining mixture in the presence of an azeotrope former adapted to form Van azeotrope with the heavier portion of said relatively paraflinic oil fraction. 4. A process for separating relatively parafnic oil fractions from relatively non-parainic Y oil fractions which comprises fractionally distilling an oil fractionrcontaining a mixture of saidv relatively paraftlnic and relatively non-paraffnic oil fractions in the presence of an azeotrope Y Y presenceof an azeotrope former adapted to form This application is a continuation-in-ipart of the earlierapplication Serial No; 360,264',- illed Iclaim: f n 1. Ar process for producing llubricatingfoil from van oil 'containing relatively'parailinic and` rela-1' Y tively non-paraflinic' oil fractions VVwhich' com- Y prises distilling said oil in'the presence `of a compound selected from theclass; consisting of polyglycols and derivativesY o'f"po'lyglycols having-a' boiling point not moreV than about 100 F. below' or4 about 40" Fg above the boiling point of said4 oil and capable of forming:v a lower boiling azeotrope with said relatively parainic oil frac-i tion and thereby distillingsaid .azeotrope from the remaining. j relatively nonparaflinic' oil :fractions.
2. A Aprocess' for separating relatively paraf- Y te . heavier relativelyparaiinicoil fractions and rela- V selected: from the class consisting of polyglycols.and derivatives of polyglycols adapted toforman azeotrope with the lighter portion of said vrelatively paraflinic oil fraction, distilling. said azeotropeffrom the lremaining mixture of tively non-parainnic oil 'fractions and fraction-f' ally distillingfthe Vremaining mixture inf'the presence of asecond azeotrope former Whichis different from vsaid first' azeotrope former adapted to form an azeotrope4 with'th'e 'heavier portion' ofsaid relatively paraflinic' oil fraction.
Y restarts f 6. A process'for'separating!'relatively'lparaflnic oil fractionsfrom relatively non-parainic `'oil fractions which comprises fractionally distilling an oil fraction Ycontaining Va mixture of *said relatively paraii'inicl and relatively non- -parainic oil fractions in the presence of an azeotrope formerselected from the class'con'- fsisting of. polyglycols* and derivatives of poly pglycols adapted to `form lan azeotrope with the lighter portion4 of vsaidfrelativelyparainic oil fraction, distilling` said azeotrope from the remaining mixture of' heavier relatively parafiinic oil fractions and relatively non-parafnic oil fractions and fractionally distilling the remainingmixture in the presence of` a second azeotrope former having a higher boiling point than said first azeotrope former adapted to form an azeotrope with the heavierportion of said relatively paraffinic oil fraction.
'7. A process for separating relatively parainic oil fractions from relatively non-paraffinic oil fractions which comprises fractionally distilling an oil fraction containing amixture of said relatively parainnic and relativelynon-paraflinic oil fractions in the presence of terta-ethylene glycol adapted to form an azeotropewith the lighter portion of said relatively parafnic oil fraction,
distilling said azeotrope from the remaining miX- ture of heavier relatively paraffinic oil fractions and relatively non-paraftinic. oil fractions and fractionally distilling the remaining mixture in said'- compound.
13. A process for separating asphalt, resi'nsLV aromatic and, naphthenic oil fractions from an oil containing the same and param'c oil fractions'whichs-comprises distilling saidoil in ythe presence of an azeotrope former selected from the class consistingeo'f polyglycols and derivatives `of polyglycols having a boiling pointnot `more than about 100' F. below ory about 40 F. above Y Ythe boiling point of said oil and capableof formthe presence of an azeotrope former adapted to Y form an azeotrope with the heavier portion of said relatively parainic oil fractions. 8. A-process for producing lubricating oilfrom,
ingv a lower boiling azeotropeV with Asaid paraflinic oil Vfractions and' separating said azeotrope from E theremaining undistilled asphalt, resins, aromatic and naphthenic oil fractions.
14.VV A Yprocess for separating asphalt, resins Iand the like substance from an"oi1 containing the same which comprises distilling said oil in the n presence of a compound selected from the class` l consisting of polyglycols and derivatives of .polyglycolsV having a boiling `point not more .than
about 100 F. belowor about 40 above the4 .boiling point of said oil and'capable of forming a lowerlboiling azeotrope with oil components .other than said asphalt, resins and,y like ysubstances desired to be separatedvfrom said oil and separating said oil components from said asphalt, resins and vlike( substances together with said compound. l
15. A process for separating asphalt, resins. aromatic and naphthenicqoil fractions from an oil containing the same and parainic oil fraci tions which comprises distilling said :oil in the an oil containing relatively parafnic and` relatively non-paraninic oil fractions which comprises distilling said oil in the presence of a relatively high. boiling polyglycol capableY of forming an azeotrope with said relatively parafnic oil fraction and thereby distilling said azeotrope from the remaining relatively nonparanic oil fractions. i
9. vA process according to claimI 8 in which said polyglycol comprises tetraethylene glycol.
10. A process fo-r producing lubricating oil from an oil containing relatively parafnic and relatively non-parainic oil fractions which comprises distilling said oil in the presence of a relatively high boiling ether of a polyglycol capable of forming an azeotrope with said relatively paraiinic oil fraction and thereby distilling said A azeotrope fromv the remaining relatively nonthe same which comprises distillingsaid oil in' the presence of a compound selected from the class consisting of polyglycols and derivatives of polyglycols having a boiling point not more than about 100 F. below or about 40 F. above the boiling point of said oil and capable of forming a lower boiling azeotrope with oil components other` than said asphalt, resins and like substances desired to be separated from said oil and separating said oiljcomponents from said presence of an azeotrope former selected from .the class consisting of polyglycols and derivatives of polyglycols having a boiling Apoint not more than about 100 F. below or about 40 F.. above the boiling point of said oil capable of forming a lower boiling'azeotrope with said paranic oil fractions and separating said azeotrope-1 from. the remaining undistilled asphalt, resina/aro-r matic andnaphthenic oil fractions.
16. A process for separating wax,'as`phalt. resins, aromatic and naphthenic oil fractions from` an oil containing the same and parafnic oilK fractions which comprises distilling Ysaid oil in the presence of anlazeotrope former selected from i theclass consisting ofpolyglycols and derivatives of polyglycols having aboifling point not. more than about 100 F. below or about 40 F.7above the boiling point of said oil and capablevof forming a` lower boiling azeotrope with said parafnic *oil fractions and wax andseparating said azeo- Y Ytrope from the remaining undistilled asphalt,
resins, aromatic and naphthenic oil fractions and separating wax from said parafnic oil fractions.
17. A`process for the separation of relatively i paraffinic'oil'fractions from relatively non-parafnic oil fractions which comprises distilling said oil in the presence of a compound selected from the class consisting of polyglycols and derivatives of polyglycols havinga boiling point not more than about F. below or about 40 F. Vabove the boiling point of said oil and capable of forming a lower Iboiling azeotrope with said relatively paaffinic oil fraction and thereby distilling saidazeotrope from the remaining Vrelatively nonparaiinic oifl fractions.
18. A process forv the. separation of relatively parainnic oil fractions from relatively non-parafnic Voil fractions which vcomprises fractionally distilling an oil fraction rcontaining a mixture `of said relatively paraflinicy and relatively non-parainic oil fractions to producea pluralityof fractions, distilling each of said oilfractionsin the ia'sphalt, resins 'and' like substances together with I presence of an azeotrope former selected from the class consisting of polyglycols and derivatives of polyglycols having a boiling point not more than about 100 F. `below or about 40 F.
above theboiling point of the fraction undergoing f distillation and capable of forming a lower boiling vazeotrope with said relatively paraii'nic oil fractions Vand thereby separating said azeotrope from the remaining relatively non-parainic oil fractiona-separating azeotrope former from said relatively vparainic oil fractions and blendingsaid separated relatively -parafiinic oil fractions.
19. .A process as in claim 17 in which said compound'comprises an acid ester of a polyglycol.
y'10 ether of Vtetraethylene glycol.
GEORGE R. LAKE.