US2041275A - Method for treating oils - Google Patents

Description

vMaly 19, 1936. u. B. BRAY METHOD FOR HEATING oILs Filed May 23 1933 Patentedl May v19, 1936- UlTED-sTATEs nmrnon Foa :mme ons Ulrlc B. Bray, Palos Verdes Estates, Calif., as-

sgnor 4to Union Oil Company of California, Los eles, Calif., a corporation of California Application May 23, 1933, Serial No. 6l2,4.32v

9 Claims.

The present invention relates to a method for separating asphalt from oil. More specically, it i relates to a method for separating asphalt from asphalt containing ,pils in a plurality of stages,y

A ,o This invention is a continuation, in part, of my co-pending applications Serial No. 466,189, led July 7, 1930; SerlalfNo. 610,130,'led May 9, 1932 and Serial N0. 659,854, flledMarch-, 1933.

In my co-pending application Serial No.

'10 466,189, Idisclosed a two-stage process for thev separation of asphalt and wax from crude oils ortopped crudes containing the saine to produce lubricating oil. In the first stage' of the process,

the asphalt ,andl wax containing/oil was` coml' mingled withta liquefied normallyrgaseous hy? drocarbon solvent, such as liquid propane, under pressure suicient to maintain the-propane in a liquid state. This permitted the-asphalt to` precipitate from -the'solution oi' oil and propane andsettle to the bottom of the decanter. 'Ihe oil solvent solution was separated from the precipitated asphalt and was then chilledl by evaporatingV a portion of the propane under reduced pressure. This caused the .wax to precipitate from 1 the solution. The wax -was separated and then the propane was removed from the remaining oil solvent solution to produce a lubricating oil which was substantiallygfree from asphalt and wax.

my -co-pending application Serial No.

m a 610,130, l disclosed a process for the co-precipita- Y tionyof asphalt and wax by means of a liqueed4 normally gaseoushy'drocarbon solvent, in ,par-

ticular, liquid propane, wherein the asphalt and Vwiso: containing oil was commingled with the sol- 3.5 vent 'underpressure suillcient to maintain the solvent in aliquid state. yThe oildissolved in the liquid propane and the asphalt was thrown outlj oi solution. A portion of the liquid propane was allowed to vaporize under reduced pressure to 40 chill themixture' of oil, solvent, wax and asphalt to asu'clently low temperature to cause precipitation oi the wax. The ebullition or boiling which accompanies the vaporization Vof the liquid propanecaused a violent, agitation oigthemass and the 'precipitated asphalt acted as nuclear or gathering bodies for the agglomeration o1 the wax as it was precipitated at the lower temperature attained. The agglomerated particles of waxend asphalt were then separated from the oil solvent solution and the solvent was' removed from the oil. This oil was a lubricating oil substantially free from asphalt and wax. l

In the foregoing process, I have observed that the lubricating oil produced isalso free from the (Cl. 19H-13) Conradson carbon value.v It is my belief that the presence of these heavy viscous oil fractions in lubricating oils are largely responsible for the y high Conradson carbon values or lubricating oil. Such fractionswere thrown out of solution by 5 chilling the oil containing both asphalt and waxl and settled-to the bottom of the decanter. In other words, I have discovered that chilling an oil to precipitate wax will also effect precipitation of the heavy viscous oil fractions, which, when 10, separated from.v the oil, will produce a lubricating oil of lower Conradson carbon value than when such fractions are retained in the lubricating oil.

In my co-pending application ASerial No. 659,854, I disclosed a process for the co-precipita- 15 tion of asphalt and heavy viscous oil fractions from asphalt containing residues substantia1ly. free from wax. Such precipitation was eii'ected by mixing a liquefied normally gaseous hydrocarbon solvent, in particular, liquid propane, with 20 .thel asphalt containing oil under pressure sufcient to maintain the solvent liquid `and then reducing the pressure on the mixture to lpermit evaporation of avportion of the propane which i chilled the oil solvent solution and precipitated 25.` the asphalt and heavy viscous oil fractions from solution. Ihe precipitated mixture was removed from the oil solvent solution and was then heated to vaporize residual propane. The asphalt was recoveredas a mixture of hard bitumen and heavy 30 viscous oil fractions.h The oil solvent solution substantially freel from asphalt andfheavy viscous 4 so-called stabilizing" methodnow conventional in the natural gasoline industry. They are the Ml overhead` obtained. They are liqueled by compression and cooledin the conventional manner and are drawn od into pressure chambers where they are maintained in a liquid state until used.

A typical` analysis of suchl a fraction is 6.72% 50 ethane, 72.2% propane, 19.91% isobutane and 1.17% normal butane. Such a fraction may be maintained in a liquid state at a pressure of-125' lbs. per squareinchat atemperature 'of about 55 F: The predominatlng hydrocarbon member in this mixture is propane `and hereafter when I use the word propane or liquid propane" I v am referring to such a fraction.

rtlwiil be observs that by the term Aaspmtlty Iintend to include -such asphaltic and non-waxy fractions which will separate or precipitatefrom" u asphalt containing oils when these'oils are com- The present invention is also related to a treatment of asphaltic oils which are substantially free from wax. As stated in my aforementioned co-pending application, Serial No. 659,854 substantially al1 petroleum oils and particularly asphalt containing oils contain such heavy viscous oil fractions irrespective of whether they contain wax. It will be observed-that all asphaltic oils contain more or less wax; some contain `large yquantities of wax, while others arev substantially 'freebut nevertheless contain a -small quantity.

Thus, such California crude oils as McKittrick, Poso Creek, Coalinga. Summerland and Sunset are typical asphaltic crudes containing veryrlittle wax, while other crudes as Montebello', Kettleman Hills, Santa Fe Springs, Elwood, Torrance and SantajBarbara are classed as mixed base crudes, that is,they contain large quantities of wax as well as asphalt. Nevertheless, substantially all of these oils contain highy molecular weight bodies whicharel responsible for the high Conradson carbon value ofv lubricating oils. In treating oils substantially free of wax, it is customary to maintain the temperaturesy for separation of asphalt at approximately atmospheriai. e. about 70 Fl to 80 F. At such temperatures, the heavy viscous oil fractions are soluble in the oil solvent solution and will -not precipitate from sol lution.' My present inventionfis directed towards removal of such fractions from oils. It is particularly directed to treatment of asphaltic nonwaxy oils. However, as will be-described below and as has been stated above, vit is also applicable to asphaltic wax containing oils;

By the present invention, I propose to' sepa- `rate the asphaltic material in asphalt containing oils substantially free from wax in a plurality of stages.' in particular, in two stages. I have now discovered that I may precipitate and' recover two entirely different types of asphalt, that is,

.a hard asphalt and a soft asphalt, if the prel cipitation by solvents and separation is eifected in :two stages. In one stage of the process, the4 oil containing asphalt is mixed withv aliqueed normally gaseous hydrocarbon solvent under `f pressure suiilcientto maintain the solvent inthe liquid state lto precipitate hard asphaltic material and at a temperature of substantially atmospheric, i. e.. about '10 F. to 80 F. The precipitated asphalltic` material is separated from the "oil solvent solution and then the oil solvent solution which has been freed from the hard asphalt is chilled in a second stage to a sufficiently low temperature, i. e. about -40 F. to 0 Eto precipitate further quantities of asphaltic' mafterial. The character of the asphalt recovered in the 'il'rst stage comprises a substantially hard asphalt or substantially pure bitumen, while the asphaltic material recovered inthe second stage comprises the heavyviscousoil fractions. aforementioned whichare soluble'. inthe oill solventsolution 4at atmospheric temperatures; Chilling of -the oil solvent solution;- from which .the hard asphalt has beenre'mdved will con'geal vs uch precipitate out of solution:

heavy viscous oil fractionsy and cause 4 them tomingled with liquid propane or other solvents. Thus, the heavy viscous oil fractions precipitated from solution by means of solvents at low temperatures will be considered an asphalt or asphaltic material as well as the hard asphalt or substantially pure bitumen separated from the oilin the rst stage at atmospheric temperature. Such asphaltic material recovered in the second stage may be considered a secondary asphalt or a pseudo asphalt. It is of light brown color and of about road oil consistency.

If ythis, process is operated on a waxy oil, the wax will precipitate with the viscous oil fractions in the second stage depending on the temperature at which the second precipitation is accomplished.

With the above discussion in mind, it will be perceived that it is an object of my invention to by means of a solvent in a plurality of stages, the first stage or stages being operated at a higher temperature than the second or subsequent stages.

It is a further object of my invention to separate asphalt from oils by means of solvents in two stages wherein a substantially hard asphalt is 4precipitated and separated inthe iirst stage and a soft asphalt is precipitated and separated in the second stage, the precipitation and separation in the second stage being carried out at a lower temperature and pressure than that in the rst' stage.

A further-object of my invention'resides in commingling an asphalt containing oil vsubstantially free from wax with. a liquefied normally gaseous hydrocarbon solvent under'pressure sufficient to maintain the vsolvent in a liquid state and at atmospheric temperatures oi' about 70 F. to 80 F. to precipitate asubstantially hard asphalt, separating the precipitated asphalt from the oil solvent vsolution and then reducing the temperature of the oil solvent solution to approximately 40 F. to 0 F. by lowering the pressure to eifect vaporizationl'of a portion of the solvent and thus precipitate heavy viscous oil fractions or vmalthas or secondary soft asphalt, separating the latter precipitated'asphalt from the oil solvent solution and then separating the 'the liquid propane, through valve 1 into line .2.

'I'he amount of propane introduced into line 2 will depend upon the character voi the oil and the temperatures desired in th second asphalt precipitator or decanter E Thepmixture of liquid propane and residuum is passed through turbulence or milling coil l into the iirst decante'r `or asphalt precipitator I where the asphalt in the'topped residuumv is precipitated andv settles rapidly as a slurryv of substantially pure bitumen. or hard asphalt containing some oil and'propane. A pressure of approximately 125 lbs. per square,y

meh anda temperature of about '10 'F.'to 80 F.

is m 'the danter s. 'rms pressure smdani, is .www propane imma.

`lire points. passing through mist extractor I8 is sent through 2,041,275' in decanter 9. The amount o'i propane intro-` duced into the oil will also depend upon whether itis desired to remove the asphalt `at the bottom of vdecanter 9 as a liquid fraction, the volumetric ratio of propane to oil in decanter 9 will be within a range of OLS-6 to 1, depending upon the` character of the oil and the degree to which itv was topped. Higher volumetric rations-'will precipitate the asphaltlas a slurryof substantially pure bitumen and propane.

The asphalt precipitated in decanter 9vis withdrawn via line I8 controlled by valve II and is forced by pump I2 under pressure through heating coil I4 where'it is heated to a suiiiciently high temperature to melt the asphalt and vaporize residual propane. The heated mixture is then passed through line I5 and iiashed through pressure reduction valve I6 on line I5 into evaporator Il which operates at a lower pressure. Superheated steam is introduced into the evaporator I1 through perforated pipe I8 to supply additional heat and to reduce the asphalt to the proper specification, generally only as regards flash and The overhead from evaporator I1 sent through line 33 controlled by valve to.

storage tank 335.

The over-flow from decanter 9 consisting of propane and oil free from hard asphaltv` and also wax but `containing heavy viscous oil fractions, tars, maltha or pseudo asphaltic material is sent through line36` and pressure reduction valve 31 kinto the vsecond `decanter or asphalt precipitator 38. In decanter 38 sufficient propane vaporizes to reduce the temperature of the remaining material to a suiliciently low temperature Y which causes the aforementioned heavy viscous oil fractions and the like to precipitate from solution. The desired low temperature is obtained by controlling the pressure in decanter 38 by the proper operation of valve 48 on 'line 38 and compressor 28 which is connected to the decanter by lines 21 and 39. The pressure to be maintained iny decant-er 38 will generally be about 0 to 25 lbs. gauge which corresponds to a temperature of ap- Q proximately between -40`F. to 0 F. As the :propane solution passes through'valve 31, its

88 and run downto propane storage tank 4'. An

equilibrium line 4I controlled 4by valve 42 connects the decanter 9 with the highpressure stor- The material precipitated in decantersettles tothe bottom of 'the decanter and isy removed lby line 43 controlled by valve 44 and pump 45 as a mixture of v.propane and heavy viscous oil frac'- tions and asphaltic material which was not separated in the ilrst decanter 9., Due to the light character of the material precipitated in decanter 38, sufficient settling time must be provided to .the asphalti'c material to stratify from the solution oi oil and propane. If desired, decanter 38 may be operated` as a chilling column without effecting settling of the precipitated material. The chilled mixture may then be passed to a plurality of settling chambers operated alternately when sufcie'nt time may be provided to permit the precipitated asphaltic material to settle or stratify from the-oil'solvent solution. The precipitated asphaltic material may then be removed from the bottom of the settling chamber as a product substantially free from the lubricating oil fractions.

Pump 45 forces the mixture settling at the bottom of decanter 38 underpressure through heat ing coil 46 where it is heated toa sufficiently high temperature to render the precipitated material fluid and to vaporize residual propane. The heated mixture is then passed into line 41 and ilashedthrough pressure reduction valve 48 on line 41 into 'evaporator 58 which operates at a lower pressure. Superheated steam is introduced into evaporator 58 through perforated pipe 5I for supplying additional heat and to reduce the asphaltic and viscous heavy oil fractions to a proper speciilcation, such as flash and re points. The overhead from evaporator 58 passing through mist extractorl 52 is sent through line 53 to cooler 54 and then to separator 55. The uncondensed'propane from separator55 is sent through line k56 controlled by valve 51 to lines 25, 28 and 21, t'o the 4suction of compressor 28, where its pressure is raised to that in the high pressure systemand is sent via line 29 to cooler 38 where it liquefies and runs down into propane storage tank 4. ny condensed light oil inseparator 55 is Withdrawn through line 58 and condensed water throughline 59. Thel pseudo asphaltic material or heavy viscous oil fractions is taken from the bottom 'of evaporator 58 and sent throughv line 68 controlled by valve 6I to storage tank 62.

The over-ilow from decanter 38 consisting of propane and oil free from asphalt and heavy viscous oil fractions, malthas and the like and also wax is sent through line 85 by pump 66 and thenthrough line 61 controlled by valve 68 to acid treatment and neutralization with alkali, valve 18 on line 68 being closed. If desired, valve 58 on line` 81 may be closed and valve 18 on line 58 opened so that the over-flow from decanter 38 may Dass into line 88 and then through valve 18 into evaporator or heater 1I provided with mist extractor 12 where the propane present is vaporized bythe aid `oi? steam circulated through the closed steam coil 13. The vaporized propane -passes out o! the heater through line 14 controlled by valve 15 and then passes through cooler 16 into lines 18 and 21, to compressor 28, cooler 38 into storage tank 4. 'Ihe depropanized oil passes from heater 1I by means of line 18 controlled by valve I8 into storage tank 8|. This oil will comprise a lubricating oil of low Conradson carbon value and `vill be substantially free from heavy viscous oil fractions, wax and asphalt. The oil may be acid and alkali-treated prior to its use or may be treated by other methods now conventional. If desired, the over-flow from decanter 38 may be acid and alkali treated in the 'presence of propane under pressure prior to depropanization in heater 1I.

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.

I claim:

1. A process for the separation of asphalt from oil which comprises commingling said oil with a liquefied normally gaseous hydrocarbonsolvent to precipitate asphalt, 'removing the precipitated asphalt from the oil and solvent, chilling the oil and solvent to precipitate a .further quantity of asphalt and removing said second precipitated asphalt from the oil and solvent.

2. A process as in claim 1 in which the liqueed normally gaseous hydrocarbon solvent contains a substantial proportion of propane. l

3. A process for separatingasphalt from oils containing thesame but which are substantially free from Wax which comprises mixing said oil with a .liquefied normally gaseous hydrocarbon solve'nt and precipitating the asphalt from the oil and solvent in a plurality o f stages.

4. A process for separating asphalt from oilsv containing the same but which are substantially free from wax which comprisesmixing said oil witha liquefied` normally gaseous hydrocarbon solvent to precipitate asphalt, separating said precipitated asphalt from the oil solvent solution and chilling said oil solvent solution to precipitate further quantities oi.' asphalt andseparating said second precipitated asphalt from the oil solvent solution. v

5. A process for separating asphalt from oils containing the same but which are substantially ing operated at a higherl temperature and pressure than the second of said stages whereby a jtion of the prpane and thus chill the oil to substantially hard asphalt is precipitated in said rst stage and a substantially soft asphalt is precipitated in said second stage.

- 7. A process for separating asphalt from oils containing the same but which are substantially free from wax which comprises mixing said oil witha liquefied normally gaseous hydrocarbon solvent under Sup'eratmospheric pressure to precipitate asphalt, separating said precipitated asphalt from the oil solvent` solution and reducing the pressure on said oil solvent solution to vaporize a portion of the solvent'to`chi1l the oil and precipitate further quantities of asphaltic material and separating said further quantities of precipitated asphaltic material from the oil solvent solution.

8. A process forseparating asphalt from oils containing the same but which are substantially free from Wax which comprises mixing said oil with liquid propane under pressure suiilcient to maintain said propane liquid to precipitate asphalt, separating said precipitated asphalt from the oil and propane solution, releasing the pressure on the oil and propane to vaporize a porprecipitate further quantities of asphalt, separating said further quantities of precipitated asphalt from the oil and propane and separating the propane from the oil.

9. A process for separating asphaltfrom pils containing the same but which are substantially free from wax which comprises mixing said oil with propane under pressure suflicient to maintain the propane liquid to precipitate a substantially hard asphalt and at substantially/'atmospheric temperature, separating said precipitated hard'asphalt from the oil propane solution, reducing the pressure on the oil propane solution to Vaporize a portion of the propane and thus chill the oil to precipitate a soft asphalt, separating said precipitated soft asphalt from the oil and remaining propane and separating the remaining propane from the oil.

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