US2006098A - Method for producing lubricating oil - Google Patents

Description

June 25, 1935.7. u. B. BRAY METHOD FOR PRODUCING LUBRICATING OIL Filed Jan.- 26, 1955 2 Sheets-Sheet 1 uzEomm L wmwzwazou 20 Q HHMKNWIF wm%\ v .HZK ON "Area KNEE @E A &

n54 uammnsw l W VK June 25, 1935. u. B. BRAY METHOD FOR PRODUCING LUBRICATING OIL 2 Sheets-Sheet 2 Filed Jan. 26, 1955 MMH 240mm Patented June 25, 1935 2,000,095 ms'rnon roa PBOgIIJLCING LUBBICATING UNITED STATES PATENT OFFICE Ulric B. Bray, Palos Verdes Estates, CaliL, as-

signor to Union Oil Company of California, Los Angeles, Gaii1'., a corporation of California Application January 26, 1935, Serial No. 3,613 15 Claims. ('01. 190-34) This invention relates to the production of lublbs. The extraction of the oil from the asphalt at ricating oils from crude oils containing asphalt such pressures results in an asphalt substantially and wax and is a continuation in part of my free of oil and a solution of oil in the liquid peapplication Serial No. 486,724, filed October 6, troleum fraction. This solution contains subtan- 5 1930, and a continuation in part ofmy applicatially all the wax present. in the crude oil. 6

tion Serial No. 694,839, filed October 23, 1933, It has also beenfound that oil containing aswhich was divided'from my application Serial No. phalt and impurities such as wax may be first 466,189 filed July 7, 1930. freed from the asphalt by a primary extraction This invention is described but not claimed in with a light solvent such as the solvent described 10 my copending applications Serial No. 597,419 filed above and that the impurities such as wax, may 10 March 7, 1932 Serial No. 625,562 filed July 29, then be removed at a suitable temperature by the 1932;v Serial No. 625,563 filed July 29, 1932; Serial aid of a heavier solvent, such as naphtha in which No. 650,995 filed January 10,. 1933; Serial No. the wax is substantially insoluble at the low tem- 693,644 filed October 14, 1933; Serial No. 707,641 perature employed. By heavier solvent, I mean is filed January 22, 1934; Serial No. 707,642 filed one of high r ilin point than th li t s lvent 10 January 22, 1934; Serial No. 721,602 filed April previously described.

20,-1934; and Serial No. 749,649 filed Oct. 23 1934. Advantage is taken of the high volatility of the The invention is also described but not claimed in l ht olvent to cause a cooling of the oilupon a my Patents 1,944,491 and 1,949,989 which are also release of pressu e to produce the p ion of divisions of my copending application Serial No. the contained wax. A further advantage in cool 20 4 ,139 filed July 7, 1930, 1 ing the oil in this manner is to bring the oil to a It has been discovered that superior lubricating p op r temperature for acid treatment. 3? acid 11 and asphalts can be obtained from crude 11- treatment, I intend toinclude treatment with by causing separation of the lubricating oil from acid followed by the p o neutralization and/or 25 the asphalt at temperatures below that at which y treatment. 1 i

i deleterious changes are induced in the'oil. 1 I1 alarge p p rtion of the Pr 18 It has been found that if oil containing asphalt ved from the s u on after the asphalt has is heated-in the presence of the asphalt, the latter been separated, the rema t o becomes catalyzes certain reactions in the oil which result too us a d not of sufllciently low specific in the destruction of those characteristics of the gravity to Permit Satisfactory avio in the 80 lubricating oils which are most desirable. dewflxing p at hich is conveniently accom- It has been found advisable to cause the sepp ed in a centrifuge. Difllculti. are also *aration of asphalt from the oil by means of volate d n ca y reat ls of hi tile solvents which are capable of dissolving the Viscosityy ve n avoids these difllculties oil and any wax and which do not dissolve the by mixing the oil with naphtha before W S. 35

asphalt. Such solvents are light petroleum fracto reduce the Viscosity and Place the oil in P p tions, such ascasinghead gasoline and naphtha condition for downing The reduced s ty and also petroleum fractions normally vaporous is also advantageous in c mical treatment of at ordinary temperatures and pressures. Other the If p is expanded at y w D e 40 solvents which may be used are alcohol, ether, Sure into the oil Prior to downing, it may a so 40 mixtures of alcohol and ether, acetone, etc. I have a cooling eiieot Similar to that a ed, by prefer to. use as our volatile solvent a petroleum expansion of the p Y ap a. I fraction obtained by the rectification of natural meonthose Petroleum fractions w ch Vary from gasoline. The fractions are composed in the main kerosene to light fractions of gasoline, preferably of propane and isobutane. A typical analysis of a gasoline-like fraction having 8 p fic r vity 45 such a fraction is 6.72% ethane, 72.2% propane f a o t and boiling range of about and 19.91%.isobutane and 1.17% normal butane. ZOO-300 F. Instead of naphtha I may use other It will be understood, however, that these merely solvents or diluents, for in l. a coho s illustrate the type of traction used and the comsuch as methyl, ethyl, propyl; -butyl alcohol or 50 position may vary. mixtures of the same, ketones such as acetone or 50 In order to cause the extraction with this liquid di-ethyl k chlorinated light hydrocarbons fraction, the solution is maintained at a pressure such as dichlorethylene. trichloret y n the suflicient to maintain the propane liquid at ordilike, or mixtures of benzol with acetone or other nary temperatures. The fraction above described ketones, or mixtures of benzol and butanol or is liquid at ordinary temperatures at about other alcohols.

In addition to the power which the naphtha has of reducing the viscosity of the asphalt-free oil, it also is used as an extracting medium for wax or other material whose presence is deleterious in a finished, high grade lubricating oil. The naphtha, it used in sufllcient quantities, acts as a solvent for the oil during the removal of the wax or other impurities in a manner similar to the action of the propane solution during the removal of -the asphalt. By regulating the quantity, substantially oil-free wax may be precipitated. In comparing their volatility and specific gravity, the propane is considered to be the light solvent and the naphtha is the heavier solvent. An advantage in using both light and heavy solvents resides in the fact that the dewaxing may take place in the presence of the heavier solvent after the lighter, more volatile solvent has been evaporated with a consequent decrease in the temperature of the wax-containing oil.

It is, therefore, an object of my invention to produce lubricating oil from oil containing asphalt and impurities by extracting the lubricating oil first with a light solvent, such as propane, to precipitate the asphalt and then extracting the oil from the impurities such as wax, with a heavier solvent such as naphtha.

It is a further object to produce lubricating oil from the oil described above by maintaining pressure on the oil and light solvent during the extraction of the asphalt and to extract the impurities such as wax from the asphalt-free oil by means of a heavier solvent under reduced pressure.

It is furthermore an object of my invention to produce lubricating oil from oil containing asphalt and wax, by mixing this oil with a solvent in which the lubricating oil fractions and wax are soluble, but in which the asphalt is insoluble, and subsequently separating the wax from the lubricating oil fractions in the presence of naphtha.

It is a further object of this invention to mix the naphtha with the oil either in the presence of substantially all the propane used to precipitate the asphalt, or in the presence of only a portion of said propane, or the naphtha may be added after substantially all the propane has been separated from the oil and wax.

It is a further object of this invention to produce lubricating oil from oil containing asphalt and wax by precipitating the asphalt with a solvent for the oil and wax and to chemically treat the oil either before or after removal of the wax from the oil, and either before or after the addition of naphtha to the oil and wax.

Another object of this invention is to produce lubricating oil from oil containing asphalt and wax by mixing a volatile solvent therewith under pressure to precipitate the asphalt and dissolve the lubricating oil fractions and wax, separate the precipitated asphalt under pressure, and taking advantage of the highly volatile characteristics of the solvent by releasing the pressure and allowing the solvent to vaporize and consequently cool the oil and wax, thereby precipitating the latter, and to separate the wax from the oil in the presence of naphtha.

Another object of the invention is to produce lubricating oil in the manner described above and to make further use of the volatility of the solvent by partially releasing the pressure on the oil, solvent and wax subsequent to the removal of the precipitated asphalt under pressure, whereby the oil, wax and the solvent which remain in the liquid form are sufficiently cooled to be at the desired temperature for chemical treatment, and after chemical treatment, making use of the volatility of the remaining solvent by further releasing the pressure and precipitating the wax due to the consequent cooling.

The process will be more adequately understood by reference to the drawings which show preferred schematic arrangements of the apparatus to carry out the process described herein.

Fig. l is a schematic arrangement of apparatus in which the oil is first made asphalt-free and then is chemically treated in the presence of substantial quantities of solvent.

Figure 2 is a modification oi the schematic arrangement of apparatus shown in Figure 1.

Referring to Fig. l, topped residuum from tank 40 is passed by pump 4| through line 42 where it meets a propane solution of lubricating oil coming through line 54. The propane and residuum pass through the turbulence or mixing coil 43 and then into decanter 44. The asphalt in the residuum is precipitated by the propane and settles to the bottom of decanter 44. The precipitated asphalt resemblesa slurry and may be drawn off from the bottom of the decanter with sufficient liquid propane to permit pumping.

The asphalt propane slurry is passed through line 45, pump 46 and line 41 where it is mixed with fresh liquid propane from storage 48 sent via pump 49 and line 41. The mixture is then passed into mixing coil 50 and into decanter 5|. If it is desired to produce an asphalt containing still less oil or wax, the countercurrent washing with propane may be extended to as many steps as desired. Decanters 44 and 5| and storage 48 are maintained at the same pressure by means of equilibrium lines 55 controlled by valves 56. The pressures in 44, 5| and 48 are sufiicient to maintain the solvent in liquid state at ordinary temperatures.

The clear overflow from decanter 5| consisting of liquid propane in which is dissolved a small amount of oil is sent through line 52, pump 53 and line 54 to its connection with line 42 where it is mixed with the incoming topped residuum. The mixed residuum and propane pass through mixing coil 43 and into decanter 44 as described above.

The asphalt slurry from decanter 5| is drawn off through line I28 and pressure release valve I29.

The clear overflow from decanter 44, now consisting of a more concentrated solution of lubricating oil and propane, is next prepared for acid and alkali treatment at reduced temperature. A reduced temperature is very beneficial in the chemical treatment of certain types of oils. In order to lower the temperature of the propane solution, the pressure on the solution is decreased to a value corresponding roughly to the vapor pressure of propane at the desired treating temperature and evaporation of the propane takes place until this temperature is reached, thepressure in the meantime being held constant by automatic pressure regulating valves. A temperature of about 40 F. is desirable in the following chemical treatment and may be obtained by reducing the pressure on the propane solution to substantially 70 lbs. per square inch.

The propane solution from the top of decanter 44 is therefore passed through line 51 to the pressure release valve 58 and into expansion chamber 59 which is held at a predetermined pressure by means of automatic back pressure cooler ill.

The cooled propane solution in expansion chamber II is sent through line 02 by pump 68 to turbulence or mixing coil 01 andthence to decanter ll. Sulfuric acid is introduced from tank I by means of pump It into line it. The acid treated oil solution is decanted and the sludge is' withdrawn through line I. The oil is sent by line 10 and pump 1i into turbulence or mixing coil I1 and thence to decanter ll. Water for use in washing the acid treated oil is introduced in line II from water storage I2 via pump 13, valve llrand line it. The washed oil is then decanted and is removed from decanter ll via line ll and pump Ii into line If. The wash-water is removed from decanter I. through line It.

Alkali from alkali storage 81 is then admitted to line 82 via pump II and line II. The oil and alkali flow through turbulence coil It into decanter I! from which the alkali sludge is removed via line II. The decanted oil from I! is next sent into line fl by pump II and thence into turbulence coil 02. Wash water is also allowed to enter said coil If by passage from water storage 12 via pump II. valve ll, line Ii and line II. From the turbulence coil If, the material passes into decanter OI from which the wash water is removed via l4. Pressure is maintained on the decanters ll, ".11 and ",as above described.

The treated oil solution leaving the treating group by means of line II is passed by pump I through a second expansion valve l'l where the pressure is released to that corresponding to the dewaxing temperature. This pressure will be substantially atmospheric and its corresponding temperature will be about F. Then'the oil passes to expansion chamber ili wherein propane is evaporated and retumed by line ill to storage ll. The oil, free of propane, leaves'by ill to a dewaxing operation and then to storage, not shown. If desired, naphtha may be added to the oil-propane solution prior to evaporating the propane to give sufficient fluidity during the removal of wax.

Since the separation of asphalt from the oil by distillation of the oil cannot be accomplished without destruction of the paraffin base characteristics of the oil, the process devised by me for removal of the asphalt comprises its precipitation by means of solvents. Asphalt may be precipitated from oil by chemicals," such as sulfuric acid. I find however, that it is best precipitated by use of solvents in which the lubricating oil fractions are soluble but in which the asphalt is insoluble. Such solvents are alcohol, ether, mixtures of ether and alcohol, acetone. volatile hydrocarbon solvents, such as casinghead gasoline and light naphthas. I find, however, that the process is best carried out by the use of hydrocarbons which are normally in the vapor state at atmospheric pressure and temperature. Such hydrocarbons include propane, isobutane, butane, ethane, methane and mixtures thereof. These may be obtained by rectification of casinghead gasoline by the so-called stabilizing method now conventional in the natural gas industry. They are the overhead thus obtained. They are liqueiled by compression and cooling in the conventional manner and drawn 01! 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, 19.91% isobut'ane and 1.17% normal butane and the necessary pressure to maintain the fraction in a liquid state is approximately 125 lbs. per square inch gauge at 73 F.

The oil stock containing asphalt is mixed with this liquid solvent under superatmospheric pressure and the mixture is allowed to settle to permit the precipitation of the asphalt. The solution of lubricating oil in the liquid solvent is withdrawn from the pressure precipitator and expanded through heating coils to vaporize the solvent, leaving behind the liquid lubricating oil free of asphalt. The vapors are recompressed and cooled to liquefy them and are then returned to the system. The lubricating oil fraction produced may then be distilled at atmospheric pressure by conventional methods of distillation. such as the tube still or the shellstill with proper rectification or fractionating equipment to produce any desired cut of lubricating oil.

'Any contained wax may be extracted and the oil treated with acid. I prefer to distill the oil to leave a residue which contains the fractions having a viscosity above 400 to 500 seconds Saybolt Universal at 100 F. In other words, the

degree of distillation should leave a residue such that if it were redistilled the first fractions taken overhead would be about 600 to 800 seconds Saybolt Universal at 100? I". These figures are by their very nature approximate since they must overlap and the spread of the cut will be dependent on the percentage taken overhead. This will result in a minimum deterioration of the desirable temperature viscosity characteristics. Obviously, the oil may be more deeply topped, i. e. higher viscosity oils may be taken overhead if a partial sacrifice of those desirable qualities is not uneconomic. It is to be noted that the above criteria will hold both for batch and for flash distillation within reasonable commercial limits. It is preferred to top the crude so as to leave behind a residue which on extraction, as above, leaves a lubricating oil of the desired viscosity. However, the process may be run as well by topping the crude as far as possible, i. e. without injuring the paraffin base characteristics, extracting the residue to remove the asphalt, treating the distillate and residue with acids. alkali and/or clay and then blending to the desired viscosity.

The following is a description of a preferred method for treating a mixed'base oil, 1'. e., one containing asphalt and wax, wherein the asphalt is precipitated under conditions such as to leave the wax and oil in the propane solution. Advantage is taken of the propane solution to permit a continuous acid treatment and alkali treat ment of the oil. This is a particular advantage of this process since it permits rapid settling of the-sludge. The extreme volatility of the propaneis used to 'act as a refrigerant to cause separation of the wax. The process will be more particularly described by reference to Fig. 2.

The modification shown in Fig. 2 is described in my copending application, Serial No. 694,839, filed. October 23, 1933, of which the present application is a continuation in part.

Referring to Fig. 2, topped residuum stored in tank 31 is sent by pump ll, and meets liquid propane containing a small amount of oil coming through line 4|. The preferred fraction is that obtained as an overhead in the stabilization of natural gas gasoline. The mixture of propane and residuum pass through mixing coil 39' into decanter 40', where the asphalt in the topped residuum is precipitated and settles rapidly as a slurry. From the bottom of decanter 40', the asphalt slurry is pumped by pump 4| to meet fresh liquid propane introduced by pump 46 via line 41' from propane storage 48'. The asphalt slurry and-fresh liquid propane are sent through mixing coil 42' into decanter 43. The asphalt propane slurry from the bottom of decanter 43' is drawn off through line I45 for recovery of asphalt and propane.

The overflow from decanter 43', containing the oil and wax is sent by pump 44' through line 45' to be mixed with the topped residuum and sent into decanter 40', as explained above. The overfiow from decanter 40' consisting of propane and lubricating oil stock, in the desired ratio is sent through pump 5| for the acid and alkali treatment of the extracted lubricating oil stock. The countercurrent washing of the precipitated asphalt illustrated by the above method of operation may be extended to as many steps as desired, but in'general two decanters giving two countercurrent washings will be sufllcient to produce an asphalt satisfactorily free of wax and oil.

To the propane solution of extracted lubricating stock, acid from tank 52' is added to mixer by means of pump (or acid egg) 53, and the fiow is controlled also by valve 54'. The propane solution and acid are forced by pumps 5| and 53 through mixing coil 55' into decanter where the acid sludge settles rapidly. The addition of the acid in several dumps without drawing-*the sludge between dumps may be accomplished by tapping mixing coil 55' at various points and introducing acid at these points. The addition of acid in several dumps with the withdrawal of sludge between dumps may be accomplishedby means of additional mixing coils and acid decanters. The acid treated oil solution from decanter 60 flows continuously through line 62' into decanter 53', where water is introduced as a spray through line 68' from water storage 64' through pump 65' and valve 61' and acid reaction products are withdrawn through line 58' controlled by valve 51'. The water washed oil overflows from decanter 63 and is sent by pump 69' to be treated. Water is withdrawn via line 58' controlled by valve 59'. The soda solution contained in tank I0 is introduced by pump 'Il' through line 12' controlled by valve "f. The mixture 01' oil solution and aqueous alkali solution is forced through mixing coil 14' into decanter 15 where the caustic solution separates from the propane solution of the oil, and is withdrawn through valved line I6. The overflow from decanter 15 goes through line H to decanter 18', where water is introduced through spray 19' by means of pump 65' through valve 66. The separated water wash is withdrawn through valved line 80. The use of propane as a solvent permits the continuous and rapid treatment of lubricating stock in the manner just described.

The neutralized and water washed oil solution overflowing from decanter I8 is carried by line 8| to tank 82. The oil in 82 is then treated withdrawn through line 5'.

The above descriptions are merely illustrative of the mode of employing my invention and are not to be construed as limiting as many variations will appear to those skilled in the art within the scope of my invention which I claim to be:

1. The process for the production of lubricat ing oil from an oil containing the same which comprises mixing said oil with a liquefied normally gaseous hydrocarbon solvent under superatmospheric pressure suiiicient to maintain said solvent liquid, treating said 011 dissolved in said solvent with a mineral acid and separating said solvent from the treated oil.

2. A process as claimed in claim 1 in which the liquefied normally gaseous hydrocarbon contains a major portion of hydrocarbons having less than four carbon atoms.

3. A process as claimed in claim 1 in which the liquefied normally gaseous hydrocarbon contains a major portion of hydrocarbons of less than three carbon atoms.

4. A process as claimed in claim 1 in which the liquefied normally gaseous hydrocarbon contains a major portion of propane.

5. A process as claimed in claim 1 in which the liquefied normally gaseous hydrocarbon is propane.

6. A process as claimed in claim 1 in which the liquefied normally gaseous hydrocarbon is a hydrocarbon selected from the methane series.

7. A process for the production of lubricating oil from an 011 containing the same which comprises mixing said oil with a liquefied normally gaseous hydrocarbon solvent under superatmospheric pressure sufllcient to maintain said solvent liquid, treating said oil dissolved in said solvent with sulphuric acid, and separating the solvent from the treated oil.

8. A process as claimed in claim 7 in which the liquefied normally gaseous hydrocarbon is selected from the methane series.

9. A process as claimed in claim 7 in which the liquefied normally gaseous hydrocarbon is propane.

10. A process as claimed in claim '7 in which the liquefied normally gaseous hydrocarbon contained a major portion of hydrocarbons of less than four carbon atoms.

11. A process as claimed in claim 7 in which the liquefied normally gaseous hydrocarbon contains a major portion of propane.

12. A process as claimed in claim 1 in which the acid treated oil is treated with alkali.

13. A process as claimed in claim 7 in which the acid treated oil is treated with alkali.

14. A process as-claimed in claim 7 in which the lubricating oil mixed with the liquefied normally gaseous hydrocarbon is cooled prior to treatment with sulphuric acid.

15. A process as claimed in claim 7 in which the lubricating oil mixed with the liquefied normally gaseous hydrocarbon is cooled by vaporizing a portion of the liquefied normally gaseous hydrocarbon under reduced pressure prior to treatment with sulphuric acid.

ULRIC B. BRAY.

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