US2006096A - Process for the production of lubricating oil - Google Patents

Description

June 25, 1935. B, BRAY Er A 2,006,096

PROCESS FOR THE PRODUCTION OF LUBRICATING OIL Filed Oct. 2, 1933 J'ii'fraci Aspiak' IN VENTORS ATTORNEY.

V Patented June 25, 1935 UNITED STATES PATENT OFFICE PROCESS FOR THE PRODUCTION OF LUBRICATING OIL Ulric B. Bray, Palos Verdes Estates, and Claude E. Swift, Glendale, Calif., assignors to Union 1 Oil Company of California, Los Angeles, Calif.,

a corporation of California Application October 2, 1933, Serial No. 691,829 13 Claims. (Cl. 196-67) 5 filed August 4, 1931.

One of the distinctive characteristics of a lubri eating oil is its viscosity. For many purposes lubricants are preferred which exhibit a minimum variation in viscosity with variation in temeprature, i. e. have low viscosity temperature susceptibilities. It is generally known that the viscosity of lubricating oil produced from Western crude oils, such as California naphthene base crudes which are crudes containing asphalt, varies more with change in temperature than lubricating oils produced from Eastern crude oils or paraflin base crudes. This means that if two such oils have an identical viscosity at 100 F., the Western oil will have a much lower viscosity at the higher temperature of 210 F. than the paraflln base oil. This change in viscosity with temperature is sometimes called the temperature viscosity sus prise distillates, that is, fractions which have beenv vaporized from crude oil and condensed. Lubricating oils produced from paraflin base oils which contain substantially no asphalt are generally produced by first distilling light oil fractions including gasoline, kerosene and gas oil and also taking overhead light lubricating oils, called neutrals having a viscosity in the neighborhood of 100 to 200 seconds Saybolt universal at 100 F., leaving an undistilled residue termed bright stock. are produced by blending these neutrals with the bright stock in the desired proportion to produce oil of desired viscosity.

' The present invention is related to a process for producing lubricating oils from oils containing asphalt and/or wax. In our process, crude oil containing asphalt and/or wax is topped to remove the lighter fractions of the oil. The topped crude is subsequently treated for removal of the asphalt. and/or'wax. We prefer to effect the separation of the asphalt from the oil by means of solvents'which are capable of dissolving the oil and which do not dissolve the asphalt. Such vent liquefied normally gaseous hydrocarbons.

The lubricating pils of varying viscosity 1 We intend to include such liquefied normally gaseous hydrocarbons as methane, ethane, propane, butane, isobutane and mixtures thereof. These normally gaseous hydrocarbon solvents may be obtained by rectification of casinghead 5 gasoline by the so-called stabilizing method now conventional in the natural gasoline industry. They are the overhead obtained and are liquefied by compression and cooled in the conventional manner and are drawn into pressure chambers 10 where they are maintained in a liquid state until used. A typical analysis of such a fraction is 6.72% ethane, 72.2% propane, 19.91% iso-butane and 1.17% normal butane. Such a fraction may be maintained in a liquid state at a pressure of 15 vent, the solution is maintained at a pressure 20 suiiicient to maintain the propane in the liquid state at ordinary temperatures of about to F., i. e. at about to lbs. per square inch. The commingling of the oil with propane at such pressures, results in the precipitation of 25 asphalt which is separated from the oil as mate.- rial substantially free of oil and consisting chiefly .of pure bitumen. The remaining oil dissolved in the liquid propane contains substantially all of the lubricating oil components which are pres- 30 ent in the crude oil and in substantially the same form as they existed in the original crude oil and also the major portion of the wax present in the crude oil.

The wax present in the oil may be separated 35 by chilling the oil propanemixture to low. temperatures to. precipitate the wax after which the chilled mass is cold settled, centrifuged or filtered to remove the precipitated wax from the propane oil solution. One method -for accomplishing 0 chilling of the oil to precipitate wax is by reducing the pressure on the propane oil mixture subsequent to asphalt separation under high pressure to permit vaporization of propane which lowers the temperature of the oil and causes the wax present to precipitate from solution.

We have discovered that many lubricating ofls obtained by the extraction with solvents, such as propane from crude oil containing asphalt and wax, are composed of fractions which have 50 a relatively high gravity viscosity constant, 1. e.

a relatively high temperature viscosity susceptibility and fractions which have a relatively low gravity viscosity constant, 1. e. a relatively low temperature, viscosity susceptibility and that these oils may be separated into oils "which exhibit a low temperature viscosity susceptibility resembling oils produced from asphalt free crudes and oils which exhibit a high temperature viscosity susceptibility corresponding to oils produced by distillation of asphaltic crudes.

The gravity viscosity constant has been defined by Hill and Coates in the Journal of Ind. and Eng. Chem. in Vol. 20, 1928, page 641. This constant represents the paraifinicity or naphthenicity of an oil. A high value represents a high degree of naphthenicity while a low value indicates a relatively greater paraffinioity. Lubricatingoils from natural crudes range from .903

Eastern Pennsylvaniatype or even beyond. For

. convenience, we will call the oils which exhibit a low temperature viscosity susceptibility or gravity viscosity constant as paramnoid or oils of high parafiinicity and those which exhibit a high temperature viscosity susceptibility or gra ity viscosity constant and which resemble Westem lubricating oil distillates as non-paraffinoidor oils of low paramnicity. The propane extract which consists of such a mixture of parafinoid and non-parafiinoid fractions may be separated into these respective fractions by the use of solvents which will selectively dissolve out the nonparaflinoid components. We have found that certain solvents have a selective solvent action for the non-parafunoid oils. As solvents which will efiect this separation, we have found as useful liquid sulphur dioxide, mixtures of acetone and benzol, aniline, methyl formate, dichlorethyl ether, nitrobenzol, chloraniline, phenol and cresol. Liquid sulphur dioxide, dichlorethyl ether and nitrobenzol have been found especially valuable as solvents to separate the propane extract into oils which exhibit low temperature viscosity susceptibilities and into oils which exhibit high temperature viscosity susceptibilities.

5 of the asphalt and wax with liquid sulphur di- Gill .non-paramnoid components.

oxide in the presence of the liquid propane used to precipitate and separate the asphalt from the oil. The propane solution of oil is extracted with liquid sulphur dioxide to remove therefrom the Liquid propane is a good solvent for the paraiiinic fractions but a poor solvent for the impurities such as the gums, resins and other compounds which exhibit high carbon forming characteristics. Furthermore,

. if an oil ,is extracted under the same conditions of temperature and amounts of selective solvent, i. e. liquid sulphur dioxide, with and without the use of liquid propane, a greater yield of paraffinoiol oil is obtained when the extraction is carried out in the presence of the liquid propane.

The presence of the liquid propane during, the extraction appears to lower the solvent power of the extractive solvent, the result being that parafifinic fractions which are normally dissolved in the extract phase during the extraction withture viscosity susceptibility of the oil we may aooaoeo treat it with sulphuric acid. Such treatment removes from the oil a portion of the bodies present which possessa high temperature viscosity susceptibility. The treatment with sulphuric acid is preferably followed by treatment with clay to remove entrained sulphuric acid sludge which does not separate by settling, and-also to remove coloring matter which imparts a poor color to the oil. It is preferable to effect the chemical treatment with sulphuric acid and clay when the oil is dissolved in the liquid propane for the reason that. the sludge formed in acid treating the paraifinic fraction or rafilnate produced by extraction with liquid sulphur dioxide is a liquid sludge as contrasted to the hard sludge often obtained on treating lubricating stocks directly, that is, without the presence of liquid propane. The soft sludge obtained in acid treating the rafilnate becomes emulsified and is diihcult to make agglomerate and settle from the oil when the treatment is carried out in the absence of -a very low viscosity diluent such as liquid propane. We have found that by performing the acid treating step in the process prior to extraction with liquid sulphur dioxide that more effective results are obtained. If the oil is not acid treated before extraction with the selective solvent, there are present in the lubricating oil stock,

particularly residual oils, certain asphaltic andcolor bodies such as resins and gums which were stage so that a separation of these two phases is very difiicult. in addition, the sulphuric acid ex-- erts a selective action on the most asphaltic and unsaturated bodies of high molecular weight which tend to give high carbon residues in the- 'finished oil.

These bodies are very dimcult to remove with certain selective solvents such as liquid sulphur dioxide on account of their high molecular weight which corresponds to a low solubility in the solvent. removal of these bodies with a solvent such as liquid sulphur dioxide, aniline or dichlorethylether requires the employment of very drastic conditions of extraction, as, for example, an excessive amount of solvent or high temperature of extraction with the result that a portion of the low molecular weight high grade material or oil is lost in the extract phase along with the high molecular weight material. Obviously, the

removal of these most dimcult high molecular weight bodies by acid treatment prior to exnecessity of employing the above drastic conditions of extraction which result in a concomitant loss of a portion of the high grade low molecular weight oils.

It is preferable to perform the wax separation step prior to extraction of the oil with the selective solvent into fractions of high paraiilnicity and fractions of low parafiinicity for the reason that the low temperatures of extraction necessary with certain selective solvents such as liquid sulphur dioxide, cresol and ohloraniline causes the wax to precipitate from solution and this hinders extraction with the selective solvent. For example, the extraction with liquid sulphur dioxide, and choraniline is preferably at 20 to 50 iii. and with cresol at 5 to 20 F. depending upon the type of oil treated. For California oils, the preferred treating temperatures are lower than those for Mid-Continent oils. When treating at temperatures belowapproximateh 35 F In other words, the

wax, if present, will invariably precipitate from solution and hinder the extraction process. Moreover, it is easier to raise the temperature from a dewaxing temperature to the higher extraction temperature by simple heating than it is to lower the temperature from an extraction temperature to a dewaxing temperature.

With the above discussion in mind, it will be perceived that it is an object of our invention to isolate from crude oil or topped crude oil those fractions having characteristics which impart to the oil the low temperature viscosity susceptibility typical of parafiln base oil.

More particularly, it is an object of our invention to isolate from asphalt containing oils those components which impart to the oil the reduced susceptibility to change in viscosity with temperature which is characteristic of oils obtained from non-asphalt containing oils, that is, to separate the parafllnoid from non-paraflinoid components of the asphalt containing crude oils.-

It is a further object of our invention to separate asphalt from an oil containing asphalt, oil and wax by means of a solvent, to separate the wax from the oil and solvent and subsequently to separate the asphalt and wax free oil by means of a second solvent used in the presence of the first solvent into a paraflinoid oil and a nonparafllnoid oil. It is a further object to treat the oil dissolved in the first solvent with sulphuric acid prior to extraction with a selective solvent.

It is a further object of our invention to employ a normally gaseous hydrocarbon solvent, in

, particular liquid propane, as the solvent for separating the asphalt from the oil and the use of liquid sulphur dioxide as the solvent for separating the oil into paraflinic and non-paraflinic fractions.

It is a particular object of our invention to separate the oil, subsequent to the removal of asphalt and/or wax from the oil and subsequent to chemical purification with sulphuric acid and clay, into paraflinic and non-paraflinic fractions by means of liquid sulphur dioxide employed in the presence of liquid propane.

Other objects and apparatus of our invention will be apparent from the following description of the invention taken from the drawing which refers to a schematic arrangement of apparatus for carrying out the invention.

Referring to the drawing, an asphalt and wax containing oil, such as topped residuum from which the lighter fractions such as gasoline, kerosene and gas oil have been removed, is taken from tank I and is drawn into line 2 controlled by valve 3 by pump 4 where it meets a stream of liquefied normally gaseous hydrocarbon solvent such as liquidpropane taken from storage tank 5 via line 3 controlled by valve I and pump 3, which forces the liquid propane via line 9 into line 2. The amount of propane introduced into line 2 will depend upon the character of the oil and the temperatures desired inthe wax precipitating decanter or chilling column 43. The mixture of liquid propane and oil containing asphalt and wax is passed through turbulence or mixing coil I3 into asphalt preclpitator or decanter II where the asphalt present in the oil is precipitated and settles rapidly to the bottom of the decanter as a slurry of substantially pure bitumen or hard asphalt containing some oil and propane. A pressure of approximately 125 to 175 lbs. per square inch, and a temperature of about 70 to 80 F. is maintained in decanter II. The pressure in decanter II is maintained by means of equilibrium line I2, controlled by valve I4. which is connected to propane storage tank 5.

The amount of propane introduced into the oil will also depend upon whether it is desired to remove the asphait at the bottom of the decanter Has a slurry of asphalt and propane, i. e. as a mixture of substantially pure bitumen or hard asphalt and propane, or as a liquid fraction of asphalt containing propane and some oil. If it is desired to separate the asphalt indecanter II as a liquid fraction, the volumetric ratio of propane to oil in decanter I I will be within the range of 0.6 to 6.1, depending upon the character of the oil and the degree to which it was topped. Higher volumetric ratios will precipitate and settle the asphalt as a slurry of substantially pure bitumen and propane containing very little oil.

The asphalt precipitated in decanter I I is withdrawn via line I5 controlled by valve I6 and is forced by pump I! under pressure through line I8 and heating coil I9 where it is heated to a sufllciently high temperature to melt the asphalt and vaporize residual propane. The heated mix-. ture is then passed through line 20 and flashed through pressure reduction valve 2| into evaporator 22 which operates at a lower pressure. Superheated steam is introduced into the evaporator through perforated pipe 23 to supply additional heat and to reduce the asphalt to proper-specification, generally only as regards flash and tire points. The overhead from evaporator 22 passing through mist extractor 24 is sent through line 25 to cooler 26 and then via line 21 into separator 28. The uncondensed propane from separator 28 is sent through line 29 controlled by valve 33 to the suction of compressor 3I where its pressure is raised to that in the high pressure system, and is then sent via line 32 to cooler 33 where it liquefles and runs down into propane storage tank 5 via line 34. Any condensed light oil in separator 28 is withdrawn via line 35 controlled by valve 36 and condensed water through line 31 controlled by valve 33. The asphalt is taken from the bottom of evaporator 22 via line 39 controlled by valve 39' and passed into storage tank 40.

The overflow from decanter II consisting of propane and oil free from asphalt but containing wax is sent through line H and pressure reduction valve 42 into the wax precipitating decanter or chilling column 43. In chiller" '43 sufficient propane vaporizes to reduce the temperature of the remaining oil and propane to asufliciently low temperature which causes wax to precipitate from solution. It is preferable to gradually lower the temperature in the chiller 43 at a rate not in excess of 4 F. per minute, which is accomplished by controlling the pressure in the chiller 43 by the proper operation of valve 45 on line 44 and compressor 3|. The pressure will be gradually lower in chiller 43 to about 0 to 25 lbs. gauge, which corresponds to a temperature of approximately to 0 F. If desired the temperature may be lowered rapidly, as for example at a rate of approximately 10 F. per minute until the temperature of approximately 35? to 45 F. is reached, after which the temperature may be lowered gradually to approximately 40,F. to 0 F., at a rate of about 3 F. per minute. If suflicient propane is not present in the oil passing into the chiller 43 to obtain the desired low temperature for wax precipitation, additional propane may be introduced into" the oil passing into chilling column 43 to provide for the desired low temperature upon subsequent vaporization of propane. The propane evaporated in the chiller M will pass out of the top through line M, controlled by valve 45 to the suction of compressor 30 where the vapors are compressed, which are then cooled in cooler 33 and run down into propane storage tank 5.

Due to the fact that sumcient time must be given to gradually chill the solution of oil, wax and propane passing into the chiller :33, and to make the process continuous, a plurality of chilling columns may be provided which may be operated alternately. However, whenoperating a batch process, merely one of such chilling columnswill be sufiicient. Thus, the entire charge from decanter it may be transferred to the column A13 and the chilling may be accomplished by controlling the operation of valve 65 on line 66.

The solution of propane and oil containing the wax precipitated by internal refrigeration, is withdrawn from lines 413 via line 66, controlled by valve ll] and pumped by pump (38 into the vaportight wax separator or settler 69, where suficient time is provided for allowing the precipitated wax to settle from solution to the bottom of the settler. In batch operation, only one of these set-= tiers will suffice, but to make the process continuous, a plurality of such settlers may be provided which may be operated alternately in order to provide for sufficient settling periods. In order to prevent ebullition in the wax separator during the wax settling period, pressure is imposed upon the solution of oil. Tin's is accomplished by maintaining pressure within the separator by pump Gil. As the chilled mass in the wax separator remains in a non-ebullient state the wax settles out and is collected by vanes 5E9 operated by pulley 50 connected to a suitable source of power, not shown. If suficient propane is not present in the wax settler 69 to give good settling of the precipitated wax, additional propane may be introduced into the wax settler from the propane storage tank 5. Generally. a volumetric ratio of substantially not less than four volumes of propane to one of oil should be maintained during the wax settling operation. The precipitated wax settling at the bottom of the wax separator d9 as a slurry of wax and propane is removed via line 52, controlled by valve 53 and pumped by pump 54! through heater 55 and through line 56 into separator 51!. Vaporized propane is passed to the propane storage tank 5 via line 58 controlled by valve bit, cooler 59, lines tit and 29, compressor 80, cooler 33, and line 34. The propane-free wax is withdrawn from the separator 5?, through line iii and pumped by pump 62 into line 831 controlled by valve 64 into storage tank 65.

The solution of oil and liquid propane and free from asphalt and wax is withdrawn from the wax settler 49 via line 66 controlled by valve 6? and pumped by pump 68 into line 69, where it meets a. stream of sulfuric acid or other acids coming from storage tank I via line H controlled by valve 12 and pump 13; The mixture of acid, oil and propane passes from line 69 through mixing or agitating coil 14 where the mixture is thoroughly agitated, after which it passes through line I into the separator 16, where the sulfuric acid sludge is allowed to settle out. If sufficient propane is not present in the oil to permit good settling of the acid sludge, further quantities may be introduced into the oil either into line 69 proper to the sulphuric acid treatment, or it may be'added into line subsequent to the agitation with sulphuric acid. The acid sludge settling to aooaooo the bottom of the separator This withdrawn via line ill controlled by valve lift and pumped by pump it) through line 8t through heater til where together with the vapors from separator 57,

through cooler'bt, compressor 3i, cooler 33 and propane storage tank 5.

The acid treated oil in separator it dissolved in propane, is withdrawn via line 89 and passed into clay tower 9b where the oil and propane is treated with fuller's earth, Death Valley clay, diatomaceous earth, bentonite, charcoal and the like, for the purpose of removing any remaining sludge and neutralizing the oil. If desired, the clay treating step may be omitted in order to leave the oil slightly acid. This will facilitate the subsequent extraction step with liquid sulphur dioxide.

The acid and clay treated solution of oil in liquid propane and free from asphalt and wax, is withdrawn from the clay tower Elli via line 90 controlled by valve 92 and pumped by pump 93 through heater 5% where its temperature is raised to an extraction temperature with liquid sulphur dioxide of approximately to 50 F. and even higher. The propane solution of oil is then passed via line 95 into the lower zone of extraction column 96. The liquid sulphur dioxide from tank 971 is withdrawn via line 838 controlled by valve 99 and pumped by pump WED through line Hill into the upper zone oi-extraction column .99. Due to the difference in specific gravity of the oil introduced into the lower zorhe of the extraction column and the liquid sulphur dioxide introduced into the upper zone of the extraction column these two liquids tend to separate. 7 As the liquid sulphur dioxide descends through the extraction column it dissolves certain components present in the oil comprising the fractions in the oil of low parafiinicity, leaving undissolved the fraction of high parafilnicity dissolved in the liquid propane. It is preferable to effect the extraction with liquid sulphur dioxide in the presence of two volumes of propane to one volume of oil. Approximatelytwo to three volumes of liquid sulphur dioxide should be employed to obtain the desired separation of the oil into Daraffinic and non-parafiinic fractions.

The solution of' liquid sulphur dioxideand oil is removed from the extraction column 96 via line are, controlled by valve m3 and sent by means of line MM into vaporizer not, where the sulphur dioxide present in the oil is vaporized by aid of steam circulated through closed coil Hi6 and passes through line Hill, controlled by valve W8, compressor )9 and then'to condenser E it where the sulphur dioxide is liquefied and sent via line ill into separator M2. The sulphur dioxide soluble constituents of the oil or extract are removed from the bottom of the vaporizer Hi5 via line Ht, controlled by valve H5 and sent to storage tank H6.

The ascending column of oil in extraction column 96 dissolved in liquid propane and from which "the liquid sulphur dioxide soluble components have been removed passes via line H controlled by valve H 8 into an auxiliary separator H9 where any remaining liquid sulphur dioxide present in the oil and components soluble in liquid sulphur dioxide, which were not settied in extraction column 96 are settled out and passed via line I 26 controlled by valve I2I into line I to the vaporizer I115. The fraction of oil in auxiliary separator II9 passes via line I 22 into evaporator I23 where the propane and sulphur dioxide present in the oil are vaporized by the aid of steam circulated through closed coil I24 and are sent via line 125 controlled by valve I26 to compressor I69, condenser III) via line III into separator II2 where the propane is separated from the liquid sulphur dioxide and passes via line I21 controlled by valve I26 and pumped by pump I29 via line I30 to propane storage tank 5. The liquid sulphur dioxide in separator H2 is withdrawn via line I3I controlled by valve I32 and pumped by pump I33 to liquid sulphur dioxide storage tank 91. The treated oil in evaporator I23 which has been freed from propane and sulphur dioxide is removed via line I34 controlled by valve I35 and passed to refined oil tank I36.

The foregoing example is merely illustrative of a preferred method of carrying out our invention and is not to be taken as limiting, as many variaations may be made within the scope of the following claims by anyone skilled in the art.

We claim:

l. A process for the treatment of mineral lubricating oil which comprises dissolving said oil in a liquefied normally gaseous hydrocarbon solvent, treating the diluted oil with sulphuric acid, extracting the acid treated and diluted oil with a selective solvent for non-paraifinoid fractions to form a fraction dissolved in said diluent and a fraction dissolved in said selective solvent and separating said fractions.

2. A process according to claim 1 in which the liquefied normally gaseous hydrocarbon is liquid propane and the selective solvent is liquid sulphur dioxide.

3. A process according to claim 1 in which the liquefied normally gaseous hydrocarbon is liquid propane.

4. A process according to claim 1 in which the acid treated oil dissolved in the hydrocarbon diluent is treated with clay.

5. A process for the treatment of an oil containing "asphalt which comprises commingling said oil with an asphalt precipitating solvent to precipitate asphalt, separating the asphalt from the oil dissolved in said solvent, treatingthe oilsolvent solution with sulphuric acid, extracting the acid treated oil dissolved in the asphalt precipitating solvent with a selective solvent for nonparaiiinoid fractions to .i'orm a fraction dissolved in the asphalt precipitating solvent and a fraction dissolved in the selective solvent and separating said fractions.

6. A process as claimed in claim 5 in which the asphalt precipitating solvent is a liquefied nor-' mally gaseous hydrocarbon.

7. A process as claimed in claim 5 in which the asphalt precipitating solvent is liquid propane and the selective solvent is liquid sulphur dioxide.

' 8. A process for the treatment of hydrocarbon oil containing wax which comprises dissolving said oil in a liquefied normally gaseous hydrocarbon diluent, chilling the diluted oil to precipitate wax, separating the precipitated wax from the diluted oil, treating the dewaxed and diluted oil with sulphuric acid, extracting the dewaxed and acid treated diluted oil with a selective solvent for non-paraflinoid fractions to form an oil tracchilling is produced by vaporizing a portion of the diluent from the oil solvent solution.

a 10. A process according to claim 8 in which the selective solvent is liquid sulphur dioxide.

11. A process for the treatment of oil containing asphalt and wax which comprises commingling said oil with an asphalt precipitating solvent to precipitate asphalt, separating the asphalt from the oil and wax dissolved in said solvent, chilling the waxy oil dissolved in said solvent to precipitate wax, separating the precipitated wax from the oil dissolved in said solvent, treating the oil dissolvedin said solvent with acid, extracting the acid treated oil dissolved in the solvent with a selective solvent for non-paraflinoid fractions to form a fraction dissolved in said asphalt precipitating solvent and a fraction dissolved in said selective solvent and separating said fractions.

12. A process according to claim 11 in which the asphalt precipitating solvent is a liquefied normally gaseous hydrocarbon.

13. A process for the treatment of crude oil which comprises dissolving said oil in a liquefied normally gaseous hydrocarbon solvent, treatselective solvent and separating said fractions.

Unruc B. BRAY. CLAUDE E. swm'r.

separating said

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