US2041276A - Method for treating oils - Google Patents

Description

May 19, 1936.. u. B. BRAY METHOD FOR TREATING oILs Filed Aug. 1, 193:5

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ATTORNEY.

Patented May 1 9, 1936 UNITED STATES y 2,041,276 METHOD Fon Tammo olLs PATENT OFFICE Application August 1, 19373, serial No. 683,187 24 claims. (ci. 19o- 13% 'Ihis invention relates to a method for sepax.

rating asphalt and Wax from oils `containing the CTI same. 'I'he invention'relates .particularly to a method for removing the asphalt from oils con- .taining the same in a. plurality of stages. The present invention is a continuation in part lof my co-pending applications Ser. No. 466,189, led .ngily 7, 1930, and Ser. No. 659,855, led Mar. 6,

In my co-pending application Ser. No. 466,189, filed July 7., 1930, I disclosed a process for producing lubricating oils` and for separating asphalt and/or Wax from oilsA containing the same. In this process a crude oil residuum containing asphalt which was tapped so that the residue con,- tained fractions having a viscosity from 400 to 500 seconds Saybolt universal at 100 F. was commingled with a liquefied normally gaseous hydrocarbon solvent such as propane under pressure sufl'icient to maintain the solvent in the liquid state. `This permitted precipitation of asphalt. The solution of lubricatinggoil inthe liquid u solvent" and precipitated asphalt `was permitted to settle in order to stratify theprecipitated asphalt from the oil solvent solution. `The latter was expanded through/ heating coils to vaporiz'e the solvent and thus leave behind a lubricating oil substantially free fromasphalt. The precipitatcd'asphalt in the decanter wasremoved as a slurry of propane and bitumen which was also heated to remove `residual propane.` The propane .release inl pressure which effected chilling of the oil and precipitation of the wax from the propane solution. By reducing thepressure to sub stantally atmospheric, the temperature of the solution was reduced to approximately 40 F.

4tiongor centrifuging." The wax-free solution was heated to'evaporate the solvent and thus-to produce a lubricating: oil free from both asphalt and Wax.

As a particularfeature of the invention, the use of such .hydrocarbon solvents which are vola-l tile at atmospheric temperature and pressure hydrocarbon solvents.

was disclosed to precipitate the asphalt.- Such .hydrocarbon solvents include propane, iso-butane, ethane, methane or mixtures thereof and are obtainable by rectification of casinghead gasoline by the so-called stabilizing method now 5 conventional in the natural gasoline industry. They comprise the overhead gaseous fractionsof the stabilizing process. The gaseous fractions are liqueiied by compression and'cooling in the conventional manner and are drawn off into pressure chambers where they are maintained in the liquid state until they are used. A typical analysis of such "a fraction is 6.72% ethane, '72.20% propane, 19.19% iso-butane and 1,17% normal butane. The necessary pressure to mainl5 tain this fraction in a liquid state' at .approximately 759 F., is about 125 lbs. per s q. in. gauge. In the present invention I intend to include the use of the foregoing liquefied normally gaseous In the foregoing process, the precipitated asphalt separated from the pressure precipitator comprised a slurryof asphalt and propane from which Ythe latter was separated by distillation to leave a substantially pure asphalt or bitumen. v'Ihis type of asphalt. seriously handicaps the eicient operation of the process due to the fact that it must be heated to a fluid consistency before it can be easily pumped and handled.

In my co-pending app-ication Ser. No. 659,855,

Aiiled Mar. 6, 1933, I disclosed a process for the `separation of asphalt or asphalt and wax wherein the asphalt was separated as a liquid fraction in the first stage of the.. process by controlling the tvolumetric ratio of propane to oil in the manner as will be hereinafter described. This .retained a quantity of asphalt in the oil solvent solution. The oil solvent Isolution was then chilled to precipitate wax and also the remain- Y. ing asphalt which-`were separated .from thee-oil solvent s'olution by settling.

. By the present invention I propose to separate the asphalt present in the residuum from the oil in a plurality of stages. In the first stage of the process, the oil or residuum is commingled with 45 a solvent in such ratio as to separate the asphalt as a liquid fraction. This is. accomplished by providing a lowvolumetric ratio of propane to oil. If the ratio ofsolvent to oil is high, the asphalt is separated as a granularsolid or as a50 substantially pure bitumen containing propane. On the other hand, if this ratio is low the asphalt may be separated from the oil solvent solution as p a liquid fraction. By referring to the asphalt as a liquid fraction, it will be understood that the .asphalt separated inthe decanter when the rethe crude or residuum treated. Also tl'ie amount of asphalt recovered in this stage will depend upon the propane-oil ratio. For example, a treatment on Poso Creek residuum topped to an on-stream viscosity of 67 seconds Saybolt universal at 100 F., the minimum amount of propane that can be used to eiect a separation ofphases will exceed approximately 11/2 volumes of propane to one volume of oil. On a McKittrickfresiduurn, a separation of phases can be obtained when the volumetric ratio exceeds 0.6 volumes of solvent'to yone volume of oil. A further increase in the volumetric ratio Iof therespective oils indicates asteady decrease inpercentage recovery of the lubricating oil, while the character ofthe oil is increasingly better as to color. 'I'he amount" of asphalt recovered will also increase with an in-y l crease in the propane to oil rath). However, the

character of the asphalt recovered varies with variation of this ratio. In generalL with low volumetric ratios and high percentage of oil recovered, the asphalt separated by stratiiication is a liquid asphalt. When free of solvent it has a y low melting point and a high penetration.' By increasing the volumetric ratio, the character of the asphalt stratiiied and recovered passes from the liquid state to a solid asphalt or a substantially-pure bitumen in finely divided form. Thev penetration will correspondingly becom'elower and the melting point higher as the volumetrichave discovered that when the. propane solution of the rst stage is mixed with additional propane at the same or at a lower temperature, additional precipitation of asphalt is effected. In most cases, the second precipitate of asphalt will settle as a finely divided material or asphaltic slurry of bitumen and propane. The amount of asphalt separated in the second stage will depend upon the amount of asphalt removed, in the rst stage which will, of course, depend upon the vvolumetric ratio of propane to oil employed in the first stage. The amount of asphalt separated in'the second stage will also-depend upon the volumetric ratio of propane to oil employed in the second stage. In general, this amount will comprise from 2 to '4% of additional asphalt based on'the residuum entering the process. This additional amount may be removed by settling or filtration. The propane-oil solution may then be chilled to a temperature between 40 F. and' 40` F. to eilect a still further precipitation of asphalt or to eiect a. simultaneous precipitation of asphalt and wax where the bil treated contains wax. If desired,

i ratio isincreased; In other words, it appears.

that there is a critical volumetric ratio below which asphalt may be separated from the oil as a Aliquid fraction and above which the asphalt comprises a'granular solid or substantially pure bitumen. Ingeneral, the volumetric ratio of 6 or less of propane to one o f .oil will result irathe separation of the asphalt as a liquid fraction, whereas a ratio above this will cause the 'asphalt to be,

separated as a solid. I do not wish to be limited to this exact rratio since .the upper limit volumetric ratio'for the separation of asphalt cosity of 67 seconds Saybolt universal at 100 F.;

. the separation of asphalt as a liquid fraction may be effected at a volumetric ratio of 6 to 1 orles's. However, I` may state that liquid asphalt may be the temperature may be` reduced tofthe cloud point 0L the wax to separate pseudo asphaltic bodies prior to carrying out the dewaxing operation.

With the above discussion in mind, it will be perceivedthat it is an object o1 my invention to separate asphalt from asphalt containing oil by means of a liqueed normally gaseous hydrocarbonA 'solvent under pressure sufficient to maintain the Asolvent in a liquid state and -in an afmount sulicient to'separate the contained asphalt as a liquid fraction and then adding a further quantity ofsolvent 'to theV oil solvent solution Aand separating a further quantity of asphalt at the same or at a lower temperature than the temperature einployed in the first stage orn a portion may be removed at the same temperature after the addition of further quantities of solvent and the remainder removed at a lower temperature. A particular object of my invention resides in the. use of liquid propane as a preferred solvent' for accomplishing the above results. e

- Another lobject of my invention resides in effecting separation of asphalt froml an asphalt and wax containing oilvby means of a solvent such as propane in any amount sufficient to cause stratication of two liquid layers, one containing the bulk of oil, propane and wax together with a' small amountof unprecipitated asphalt and e the other layer containing asphalt and propane `as a liquid fraction will depend entirely upon separated from an asphaltic oil at a ratio within the range lof app oximately 0.6 tdj volumes of propane toone'volume of the oil.

Whenthe process of the iirst stage is operated to effect removal of asphalt'as a-A liquid fraction, the oil solvent solution is dark ,and its viscosity is relatively high which indicates that a substantial amount of asphalt remains in solution. This together with a small amount of oil, in separating these two liquid layers, in adding a further quantity of propane to the solution of oil and propane containing wax and unseparated asphalt to precipitate said asphalt, in separating the 'precipitated asphalt from the oil, solvent and wax, in chilling the oil solvent solution containing wax to precipitate the wax, in separating the precipitated wax from the. oil solvent soluti n and in then separating the residual solvent from the oil to Vproduce a lubricating oil substantially free of asphalt and wax.

It is another object of the invention to accomplish chilling4 of the oil solvent solution by releasing the pressure to evaporate a portion of the solvent.

Other objects and advantages of my invention will be apparent from the following description oil solution is treated in the second. stage oi.' the process forming the subject of my-invention. I

of my invention taken fromthe drawing which represent a schematic arrangement for carrying out my invention.

Referring to the drawing, an asphalt containrecovered asphalt basedon the residuum which ing oil or residuum or an asphalt and wax conappears asv a liquid phase containing approxitaining oil is taken from tank I and is passed.I mately 30% propane when equilibrium is reachedv 4 into line 2 by pump 3 where it meets liquid probetween three volumes of propane and the residpane coming fromfpropane storage tank 9 via uurn under pressure. The clear propane solution line I0, pump II and line I2 controlled by valve 'is decanted and mixed with 4 additional volumes I3. The propane and residuum is passed through of propane also at atmospheric temperature and turbulence or mixing coil 4 and then `into decanter or asphalt precipitator 5. The amount of additional asphalt based von the residuum prepropane introduced into residuum Will depend cipitated and settled to the bottom ofthe second upon Whether it is desired to remove the asphalt decanter I1. 'Ihis asphalt was recovered as a at the bottom of decanter 5 as a slurry of asphalt slurry of nely divided substantially pure bitumen and propane, i. e. as a mixture of substantially and propane at the bottom of decanter pure bitumen and propane or as'a liquid frac- Scrapers or vanes I8 prevent the asphalt from tion of asphalt and propane containing some oil. adhering` to the walls of the decanter and aid In the preferred operation, it is desirable to sepin passing the asphalt slurrygto a screw conveyor arate the asphalt in decanter 5 as a liquid frac- 25 driven by motor 26. The asphalt slurry is tion in which case the volumetric ratio of pro passed into line 21 to pump 28 which forces it pane to oil employed will be within a range of through valve 29 into lines 30 and 3.I to further 0.6 to 6 of propane to one volume of oil, depending treatment as will be described hereinafter. lupon the character of the oil or residuum, treated The asphalt settling to the bottom of decanters and the degree to which it was` topped. Volumetric ratios higher than those specified will effect precipitation and settling of the asphalt as a slurryof substantially pure bitumen and propane.v The asphalt settling to the bottom of decanter 5 is withdrawn by means. of pump 6 and line 1 controlled by valve 8rto further treatment as will be hereinafter described. a preheated uxng oil coming from line 40 which The clear overiiow from decanter 5-consisting is obtained from storage tank 33, pumped by of liquid propane and the bulk of the oil is passed pump 34 throughv line 35 to heater 36 Where it intO line I4 by means 0f pump I5 where` it meets is preheated and is then passed through line 31 a stream of liquid propane passed from storage into line 384 controlled by valve 39 and thence tank 9, line l0 and Pump H into line I2' coninto line 40 controlled by valve 4I and introduced trolled by valve I3. The mixture is then passed into line 3|v controlled by valve 32. L into turbulence coil I6` and then into decanterxj. The mixture of preheated fluxing oil and asor asphalt precipitator I1 provided with Scrapers phalttremoved from decanter 5 containing proor agitating paddles I8 operated by belt I9 pane is passed through valve 32`and heating coil from any suitable source of power not shown. 42' where the mixture is heated to a sufficiently Decanters 5 and I1 and propane storage tank high temperatureto flux the asphalt and is then 9 are maintained at substantially the Same preS- passed through pressure reduction valve 44 on sureby means of equilibrium lines 23 controlled line 43 into evaporator 45 which is operated at by valve 24 and 24. This pressure should be a lower pressure. If the iluxing loil has been suflicient to maintain the solvent in the liquid preheated' to a; sufciently high temperature to state at ordinary temperatures of approximately iiux the asphalt in line 3|, fheater 42 may/be '15 F- For the solvent given above, that is, proomitted and the-mixture flashed through valve Dane, thiS pressure iS about 125 t0'175 lbs. perf 44 into evaporator45i Steam superheated in coil in admixture. If itis desired to separately treat the asphalt from'deanter 5, it is withdrawn from the bottom of the decanter by means of pump 1 sq. in. gauge. I f desired, the pressure in decanter '46 is introduced into 45 tosupply additional heat I'I may be maintained 10Wer than that in decanter and to reduce the mixture to proper specification 5 S0 that a lOWer temperature may be provided generally, only as regards iiash Aand fire points. in decanter I`| FOI' example, the temperature The overhead from evaporator 45 passing through in decanter l1 Inay be reduced t0 approximately mist extractor 41 is sent through line 48 to cooler 40 F. t0 40 F- depending llpOn Whether the 49 and then to separator 50. The uncondensed oil contains wax or not. If the oil is substantially propane from separator 50 is'sent through line free from Wax, the temperature may be reduced 5l controlled by valve 52 to line 53 to the suction to approximately 0 F. to 40 F. If the oil contains Wax, itffis preferable to reduce the temperature to not substantially below that temperature at which Wax begins to precipitate. This oi compressor 54 where its pressures raised to sent'to cooler 55 where it is liquefied and runs down into propane storage tank `9. Any contemperature is approximately 35 Fe to 45 F- densed light oil iswithdrawn from separator 50 The temperature reduction in decanter I1 may through line 55 and condensed Water lis withbe effected by closing Valve u' and regulating drawn through line 51. Theasphaltistaken from Valve |22 on une |23 which connect$ toline 7| a the bottom of evaporator 45 and sent through line ,and theompressol 54- The Wax may the be *58 controlled by valve 59 to storage tank 60. separated in the manner hereinafter described.

The amount of propane introduced into the solution of oil and propane removed from decanter 5 will depend upon the amount of propane already present in the solution and also on the' amount of unseparated asphalt from' the first decanter I1 may likewise be treated-in accord# ance with `the method described above for treating the asphalt lrecovered from decanter 5. If desired, the preheated uxing o il may be introduced directly into the outlet |24 of decanter Stage. As an example, Santa Fe Springs long I1 in which'case the asphalt slurrywould be residuum topped t0 approximately 100 viscosity suiliciently iluid to be pumped without the aid (Saybolt universal at F.) on the overhead fof the screw conveyor 25; orby closing valve 4I stream was extracted in the rst stage with three and opening valve I26 on line 25 the hot fluxing volumes of propane to give a yield of 23% of oil may be introduced directly1 into the outlet of allowed to settle. vApproximately 2% to 4% of.

5 or 1 as described above may be separately) treated for removal of propane or may be treated .The .asphalt slurry settling to thebottom olf' and line 1 controlled by valve 8 and passed into v lines 30 and 3| where, if desired, it is mixed with that in the high pressure system and is then i the screw conveyor. Other-` possibilities of the hot iluxingfoil introduction into the asphalt I slurry will be understood by those skilled in the "'cipitated asphalt.

art. If desired, the asphalt froxn'decanter 5 may -be mixed with that of decanter I1 and treated 45 may be continuously circulated through a heater into line 3| to supply heat for fluxing and evaporation of residual propane in the pre- Heater 42 may be omitted. I1v`he introduction of hot tluxing oil into the asphalt recovered from the bottom of decanter 5 is not entirely necessary since this asphalt is substantially liquid and can be readily passed or pumped through the lines connecting decanter 5 with evaporator 45. However, it `is preferable to commingle the asphalt settling to the bottom of decanter I1 with hot fiuxing oil since this asphalt is heavy and cannot be efficiently handled.

The overflow from decanter |1 consisting of propane and de-asphaltized lubricating oil stock is sent `through line 6I by pump 62 and then through line 63 controlled by valve 64 to acid treatment and neutralization with alkali in accordance with the method described in my aforeperature of the remaining material to a predetermined dewaxing temperature which causes wax to precipitate .from solution. The desired dewaxing temperature is obtained by controlling the pressure in column 61 by the proper operation of valve 69 on line, 68 and compressor 54 which is connected to .the ,evaporator by lines 69, 10,

1| and. 53. TheY pressure to be maintained in column 61 will be' generally about 0 lbs., gauge which corresponds'to a temperature of approximately -40 F.

As the propane solution passes through valve 66, its pressure is reduced so that a portion of the propane" evaporates in column 61 and the vapors pass out of the top through line 68 controlled by valve 69, then through lines 10 `andl 1I into line 53 and compressor 54 wherel the vapors'are liquefied, cooled in 55 and passed to propane storage tank 9.

The chilled oil dissolved in the propane carrying the precipitated wax is removed from the evaporator or chilling column 61 through line 412 controlled by valve 13 by pump 14, which foces it into the vapor-tight wax separator or settler 15. In order to prevent ebullition or boiling in the wax separator during the wax settling operation, pressure is imposed upon the solution of oil. This is accomplished by maintaining pressure Within the separator by pump 14. As the `chilled mass in the wax separator remains in a non-ebullient state, the wax settles out and is collected by vanes 1 6 operated by belt; 11 connected to a suitable source of power not-shown. The

wax-freey oil dissolved in propane is withdrawn from the separatorv 15 and pumped by pump 18 through lines 19 and valve 80 into heater '8| provided with mist extractor 82 where the propane present is vaporized by the aid of steam circulated through the closed steam coil 83. The vaporized propane passes out of the' heater through line 84 controlled by valve 85, cooled in cooler 86 and thenpasses through lines 81, 10,

n1| and 53 to compressor 54, cooler 55 into storage tank 9. The dewaxed propane-free oil passes-from heater 8| by means of line 88 controlled by valve 89, through heat exchanger 9|, line 92 into tank 93.

The precipitated wax slurry containing propane settling at the bottom of the wax separator 15 is removed from the separator through line 94 and is passed through heat exchanger 9I "where it extracts heat from the dewaxed oil from the heater 8|. The wax slurry is then pumped by pump 95 into line 96 where it is mixed with a hot iiuxing oil coming from line 91 controlled by valve 98. This oil may comprise a portion of the iiuxing oil passed from tank 33, heated in heater 36 and by-passed into line 91. The mixture of hot iiuxing oil and Wax slurry is thenintroduced into line 99, heater |88 and then passed through line |8I into-separator |02. Vaporized propane is passed to propane storage tank 9 via line |03 controlled by Valve |84, cooler |05; lines |86, 1I and 53, compressor 54 and cooler 55. The mixture of propane-free fluxing oil and Wax comprising a fuel oil is withdrawn from f separator |82 through line |81 and pumped by pump- |08 into line |89 controlled by valve ||0 into storage tank II I. If desired, a portion of this mixture may be by-passed and sent through line |I2 controlled by valve H3 to pump ||4 which forces it through heater |I5 into line II6 and then into line 99 where it meets further quantities of Wax slurry from settler 15.

If it is desired to recover the wax in settler 15 as a crude petrolatum which may then be purified according to methods now conventional,the fiuxing material may comprise an initial amount of petrolatum preheated to a temperature of approxf imately 350 F. and introduced into line 99 which is mixed with the wax slurry in the proportions of two volumes of preheated petrolatum to one volume of wax slurry."The mixture is then passedinto separator |02 where propane is vaporized. .Heater' |08 may be omitted. The crude petrolatum is withdrawn from separator |02 at a temperature of approximately 200 F. which is suciently high above the melting point of the petrolatum to permit efiicient pumping and:

handlung and is then passed zthrough une |01 and pump |08, one volume of the material passlng into tank III and the other two' volumes are J recirculated into line 99 via line I|2 and pump I4 which forces the material through heater I I5 wherey the temperature is again raised to 350'F. and passed in to lines I6 and 99. 'I'he cyclic circulation through line ||2, heater II5, line II6 into line 99 is carriedlon continuously. l

If desired, the initial amountl'of preheated petrolatum introduced into line 99 may be substituted by an initial volume 'of preheated petroleum residuum which is circulated through the apparatus in the manner described above, one volume being withdrawn into tank I while the remainder is recirculated into the wax -slurry coming from separator 15. After a number of such circulations, .the material passing into line Consequently the material collecting in tank III l and the portion recirculated Ithrough heater IIB l will also comprise a crude petrolatum.

i' be acid and alkali treated prior to dewaxing in the If it fis desired to convert thefwax into fuel oil, it is preferable to mix the wax slurry coming from settler 151with a cracked residuum continuously introduced into line 99 via line 91, said cracked -residuum possessing a pour point depressant. If the 'cracked residuum is at a suiciently high temperature say about 500 F.,`heater |09 may be omitted or by-passed and the mixture passed directly into separator .|02 to permit va porization of propane. The mixture from separator |02 comprising a fuel oil is then passed to storage -tank III or a portion thereof may be recirculated into line 99 via heater H5.

If desired, the overflow from decanter 5 may manner described in my 'aforementioned co-pending application.

It is to be understood that the above is merely illustrative 'of preferred embodiments of my invention of which many variations may be made by those skilled in the art without` departing from the spirit thereof.

1. A process for separating asphalt from oils containing the same which comprises mixing said oil with a liquefied normally gaseous hydrocar-Ik bon solvent to precipitate asphalt, separating said f precipitated asphalt from the oil solvent solution and precipitating further quantities of asphalt `from said'oil solvent solution at a lower' temperature, said temperature being insuflicient to f precipitate substantial quantities ofwax.

2. A`l` process for separating asphalt from oil containing the same which comprises commingling said oil with a liquefied normally gaseous hydrocarbon. solventto precipitate asphalt, separating said precipitated asphalt from the oil solvent solution, chilling said oil solvent solution Oil to a temperature sufficiently low toK precipitate further. quantities of asphaltic material substantially free from wax and separating said second precipitated asphaltic material. from the oil solvent solution and separating the solvent from the containing the same whichcomprises mixing said oil with liquid propane under pressure sumcieht to maintain said propane liquid to precipitate asphalt, separating said precipitated asphalt `from oil and propane solution, releasing the pressure on the oil and propane to vaporize a portion of the propane and to chill the oilto precipitate further quantities of asphalt, said chilling temperature being insufficient toFprecipitate "wax, separating said further quantities of precipitated asphalt from the oil 'and propane and separating the propane from the oil.

5. The process of treating a hydrocarbony oil 4. A process for separating asphalt from oils containing asphaltic bodies and wax which comprises mixing such oil with a liquefied gas precipitant for asphaltic bodies at a temperature which permits the major portion of the asphaltic bodies but substantially no wax to separate, collecting the precipitated asphaltic bodies, lowering, the temperature of the solution of oil in said liquid precipitant whereby the remaining 'asphalticf` bodies are separated, removing the precipitated asphaltic bodies, further lowering the temperature of the solution whereby wax substantially f free from asphaltic bodies is separated, collect'- ing said wax, and removing the liqueed gas from said oil.

6. A process for separating asphalt and wax from oils containing the same which comprises mixing said oil with a'liqueed normally gaseous yhydrocarbon solvent to precipitate asphalt, separating .said precipitated asphalt from the oil solvent solution, chilling said oil solvent solution to a temperature sui'ciently low to precipitate further quantities of asphaltic material but to retain the wax in the solution of oil and solvent, separating said further quantities of asphaltic material from the'solution ofk solvent, oil and wax, chilling said solution to a dewaxing temperature to precipitate the wax and separating the precipitated wax from the solvent and oil.

7. A process -for separating asphalt and wax from oils containing the same which comprises mixing said oil with a liqueiled normally gaseous hydrocarbon solvent under superatmospheric pressure to precipitate asphalt, separating said precipitated asphalt from the oilsolvent solution,\ reducing the pressure on the oil solvent solution to vaporize a portion of the solvent and to chill the oil to precipitate further quantities of asphalt, said temperature being insuicient to precipitate wax from solution, separating said prevcipitated asphaltic material from the oil and solvent, reducing the pressure on the remaining oil solvent solution to vaporize further quantities of solvent and to chill the oil to a dewaxing temperature to precipitate wax and separating said precipitated wax from the oil and solvent.

8. A method for the separation of oil from an oil containing asphalt which comprises mixing said oil with a liquefied normally gaseous hydrocarbon to precipitate ay portion of the asphalt, removing the'precipitatedasphalt from theoil solvent solution, adding a further quantity of said` solvent to said oil solution to precipitate a further quantity of asphalt and vremoving said further precipitated' asphalt from the oil solvent solution.

'9. A method for separating asphalt from oil which comprises mixing an asphalt containing oil with a liqueednormally gaseous hydrocarbon solvent in an amount sulcient to precipitate asphalt, separating the precipitated asphalt from the oil solvent solution and adding further quan tities of solvent to the oil solvent solution to precipitate further quantities of asphalt.

l0. A method as in claim 9 in which thesoi vent comprises a liquefied normally gaseous which comprises mixing an asphalt containingoil with a liqueiied normally gaseous hydrocar- .bon solvent in an amount suilicient to separate 'zoY asphalt as a liquid fraction, separating said liquid asphalt from the oil solvent solution and adding further quantities of said solvent to said oil solvent solution to precipitate further quantities of asphalt.

13. A process as in claim 12 in which the solvent comprises a liquefied normally gaseous hydrocarbon.

14. A process as in claim 12 in which the solvent comprises a liqueiied normally gaseous hydrocarbon, the major portion of which solvent :onsistsof hydrocarbons of less than four carbon .,toms.

15. A process as in claim 12 in which the solvent comprises propane.

16. A method for separating asphalt from oil which comprises mixing an asphalt containing:l

oil with a liquefied normally gaseous hydrocarbon solvent under superatmospheric pressure in an amount suflicient to precipitate asphalt as a liquid fraction, separating said liquid fraction from the oil solvent solution under superatmospheric pressure, commingling said oil solvent solution with further quantities of solvent under superatmcspheric pressure to precipitate, further quantities of asphalt, separating said last mentioned asphalt from the oil solvent solution and separating the solvent from the oil.

17. A method for separating asphalt from oil which comprises mixing an asphalt containing oil with a liquefied normally gaseous hydrocarbon solvent under superatmospheric pressure in the proportions of 0.6 to 6 volumes of said solvent to one volume of said oil to eiect separation of the asphalt as a liquid fraction, separating the liquid ,asphalt from the oil solvent solution and sultant mixture into two layers, one containing the bulk of oil and` solvent and containing asphaltic material and the other containing the bulk of asphalt and some oil and solvent, separating the two layers, adding further quantities of solvent to the layer containing the bulk of oil and solvent and some asphaltic material to precipitate further quantities of asphaltic material, reducingthe temperature on said last mentioned mixture to precipitate further quantities of asphaltic material, separating the asphaltic material precipitated by addition of further quantities of solvent and by the reduction in temperature from theoil solvent solution andd separating the solvent from the oil.

19. A method for separating asphalt and waxr from oils containing the same which comprises' mixing an oil containing asphalt and^wax with a liquefied normally gaseous hydrocarbon solvent to separate asphalt as a liquid fraction and to leave asphaltic material in the remaining oil solvent solution, separating said liquid asphalt from the oil solvent solution, adding further quantities of solvent to said oil solvent solution to precipitate further quantities of asphaltic materia'l, separating said last mentioned asphaltic material from the oil solvent ysolution and chilling said oil solvent solution to precipitate wax and separating said Wax from the oil solvent solution.

20. A method for separating asphalt and wax from oils containing the same which comprises mixing an oil containing asphalt andwax with a liquefied normally gaseous hydrocarbon solvent to stratify the resultant mixture into two layers, one containing the bulk lof oil and solvent and some asphaltic material and wax and the other containing the bulk of asphalt and some oil and solvent, separating the two layers, adding further quantities of solvent to the layer containing the bulk of oil and solvent and some asphaltic material and wax to precipitate said asphaltic material, separating said last mentioned asphaltic material from the oil solvent solution and chilling said oil solvent solution to precipitate wax and separating said precipitated wax from the oil solvent solution. f

21. A process as `in claim 20 in which the major portion of the liquefied normally gaseous i hydrocarbon solvent consists of hydrocarbons of less than four carbon atoms.

22. A method as in claim 20 in which the solvent comprises liquid propane.

23. A method for separating asphalt and wax from oils containing the same which comprises commingling an oil containing the same with propane under superatrnospheric pressure in an amount sufiicient to separate asphalt as a liquid @action and to leave a portion of the asphaltic material in solution in the oil solvent solution containing wax, separating the oil solvent solution from the asphaltic liquid fraction, adding further quantities of propane to the oil solvent solution, reducing the temperature on said oil solvent solution and separating further quantities of asphalt and also wax from said voil solvent solution.

24. A method Vfor separatingr asphalt and wait from oils containing the same which comprises mixing an oil containing asphalt with a liquefied normally gaseous hydrocarbon solvent to stratify the resultant mixture into two layers, one containing the bulk of oil, wax and solvent and some asphalt and the other containing the bulk of asphalt and some oil and solvent, separating the two layers, adding further quantities of solvent to the layer containing the bulk of oil, Wax and solvent and someasphaltic material to precipitate further quantities oi' asphaltic material, rei ducingrthe temperature on said last mentioned mixture to precipitate further quantities of asphaltic material, said temperature being insufficient to precipitate any substantial amounts of wax, separating the asphalt precipitated by addition of further quantities of solvent and by reduction in temperature from the oil solvent solution, reducing the temperature of said oil solvent solution to precipitate wax, separating said precipitated wax from the oil solventvsolution and separating the solvent from the `oil. ULRIC B. BRAY.

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