US1988712A - Process for production of lubricating oil - Google Patents

Description

Jan. 22, 1935. u. B. BRAY ET AL 1,938,712

PROCESS FOR PRODUCTION OF LUBRICATING' OIL Filed Aug. 4, 1931 4 Sheets-Sheet 1 O O 0880 Owgm 'IVQH'EIAIND .LIOHAVS' ALISODSIA v .INVENTORS Ulric BBrg/ Claude flaw/2%.

ATTQRNEY.

E ow on ow am cm 2 0 Jan. 22, 1935. u. B. BRAY ET AL Y PROCESS FOR PRODUCTION OF LUBRiCATING OIL Filed Aug. 4, 1931 4 Sheets-Sheet 2' MAY 4 w. w. W 8

md n w A aw 9 3 VB Y 5 .w v w Jan. 22, 1935.

U. B BRAY ET AL PROCESS FOR PRODUCTION OF LUBRICATING OIL Filed Aug. 4, 1951 4 Sheets-Sheet 5 INVENTORS Ulric 51m 4 Claude E sm'fi Y?v i Jan; 22,1935. u. B. BRAY, ET AL 1,938,712

PROCESS FOR PRODUCTION OF LUBRICATING OIL ,fif d g. 4, 1931 4 Sheets-She et 4 INVENTORS Patented Jan. 22, 1935 I v UNITED STATES PROCESS FOR PRODUCTION OF LUBRICATING OIL Ulric B. Bray, Palos Verdes Estates, and Claude E. Swift, Huntington Park, Califl, assignors to' Union Oil Company of California, Los Angeles, Calif., a corporation of California Application August 4, 1931, Serial No. 555,017

11 Claims. (Cl. 196-37) This invention relates to a method and apasphaltic crudes, containing no wax, have the paratus for treating petroleum to produce lubrislope on this 'chart, independent of the viscosity cating oil. of the oils at any given temperature. Thus an oil One of" the distinctive characteristics of a-luhaving a viscosity corresponding to 600 seconds bricating oil is its viscosity. For many purposes Saybolt Universal 'at'100 F. will have thesa'me 5 lubricants are preferred which exhibit a minislope as an oil havingaviscosity of 1000 seconds mum variation in viscosity with variations in Saybolt Universal at 100 F. Acid treatment of 'temperaturai. e., have low viscosity temperature these oils has a tendency to flatten the curves, susceptibility. iIt is generally known that the i. e., making them less steep. The amount of viscosity of lubricating oil produced from Westflattening will depend upon the degree of treat- 10 em crude, such as. California naphthene base ment. We have found, however, that all commercrudes, that is, crude containing asphalt varies cial Western lubricating oils have substantially more with change in temperature than do lubrithe same slope Curve B of Fig. 2 illustrates eating oils produced from paraflin base crudes. the curve for a treated oil of the asphalt base That is, if two such oils have the same viscosity at ype having aybolt Universal viscosities of 600 15 100 F., the Western oil will have a much lower seconds at 100 F. and 55 seconds at 210 F. viscosity at 210 F-. than will the paraffin base oil. Likewise es du l lub icati g oils p d This change in viscosity with temperature is from parafiin base crude oils, containingsubsometimes called the temperature susceptibility Stantially 110 asphalt Will have PD a Y of an oil. It is one of the characteristics of the same slope on this chart independent of the Western lubricating oils that they are distillates, v i y f the il at y given mp r t r that is, are vaporized from crude oil and con- However, as the viscosity of the residuum varies densed. Lubricating oils produced from paraffin from 2000-5000 seconds, Saybolt Universal at base oils, containing substantially no asphalt, 00 F., the S ope W l Va y from 2 to 5%. The

are generally produced by first distilling light par i ular bri ht k" n u v A f 2 h s 25 oils overhead including the kerosene and, gas oil Saybolt Universal viscosities of 2350 seconds at and also taking overhead light lubricating oils 100 F. and 145 seconds at 210 F. called neutrals having a viscosity in the neigh- That p p r y os d y er n mp n n borhood of 100-200 seconds, Saybolt Universal of an oil which imparts to it a slope approaching at 100 F'., leaving an undistilled residue termed Curve A of Fig. 1 may be Said to be a measure 0f 30 bright stock. The oils of various viscosity are the paraflin base characteristics exhibited by the made by blending these neutrals and bright oil. V 7 stock in any desired proportion to obtain the It has been observed by one of us that many desired viscosity, oils containing asphalt and wax are mixtures of This variation in viscosity with temperature hydrocarbons analogous both to the hydrocar- 35 can be best illustrated by reference to Fig. 1. bons present in parafiin base oils and those pres- This chart is well known and is described and ent in asphalt base oils. It has further been obshown in the International Critical Tables, Vol. Served by one of us that during the heating of 2, page 147. It is a special type of temperature an oil containing asphalt, the asphalt apparently 40 co-ordinate chart in which the abscissa scale is induces certain chemical and perhaps certain 40 the logarithm of absolute temperature and the physical reactions at relatively low temperatures ordinate scale is an additive function .of the which tend to destroy the inherent low viscosity viscosity which has been developed experimentemperature susceptibility of the lubricating oil tally. The resulting ordinate scale is a warped fractions. This apparent catalytic phenomena logarithm scale of the kinematic viscosity upon seems to explain the observed changes although 45 which, for convenience, the corresponding scale we do not wish to be understood as being bound of Saybolt Universal viscosity has been superby this theory. It has been observed that these imposed. temperatures at which the changes appear are be- It is found as an experimental fact, that the low the vaporizing temperatures in batch distilviscosity of any petroleum oil for varying temlation (vacuum or steam) of the lubricating oil 50 pcra urcs will fall on a straight line when plotted fractions which have Saybolt Universal viscosion this chart. The steeper the slope of the line, ties above 400-500, seconds at 100 F. It is safe the greater is the variation of the viscosity with to say that no oil containing asphalt can be temperature. topped to the point where fractions above 400-500 Lubricating oils produced by distillation from seconds, Saybolt Universal viscosity at F. are 55 vaporized without a degeneration of those characteristics of the paraflin hydrocarbons which impart to the oil a low temperature viscosity susceptibility. During the distillation of the heavy oils in the presence of asphalt some change in molecular structure or configuration takes place which is attended by a change of viscosity temperature characteristics. This behavior is thought to be due to pyrolytic reactions which are catalyzed by the presence of asphalt. The above discovery is made the subject matter. of application, Serial No. 466,189. The lubricating oil components in the crude oil which have high paraillnbase characteristics, 1. e., similar to the oil represented by Curve A of Fig. 1, are converted by the distillation into oils exhibiting low paraffin base characteristics, 1. e., similar to the oil represented by Curve 3 of Fig. 1.

In order to preserve the inherent characteristic of the lubricating oil components of crude oil containing asphalt which are impairedv by distillation methods as previously described, we have. in accordance with the process of -.the above application, caused the separation of the oil and wax from the asphalt by a method wherein the lubricating oil constituents present in the crude oil are separated from the asphalt present in such a manner that the oil retains those characteristics which it possessed in the original crude oil. As a means of attaining this end it has been found advisable to cause 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 solvents are light petroleum fractions, such as naphtha, casinghead gasoline and petroleum fractions normally vaporous at ordinary temperature and pressure. Other solvents which may be used are alcohol, ether,,mixtures of alcohol and ether, acetone, etc. We prefer to use as our solvent a petroleum fraction obtained by the rectification of natural gasoline. For most purposes a fraction composed of 6.72% ethane, 72.2% propane, 19.91% iso butane and 1.17% normal butane is satisfactory. However, by using a fraction containing a higher percentage of ethane it is possible to produce a lubricating oil having a low Conradson carbon value. Such a solvent has a tendency to leave certain heavy oil fractions in the precipitated asphalt which have a tendency to form a high carbon residue. Such a fraction suitable for the production of a lubricating oil having a low Conradson carbon value would contain ethane varying in quantities from 40 to 50% by volume. It will be understood, however, that these merely illustrate the type of fractions which may be used and that the composition may vary. This fraction will hereinafter be referred to as propane for purposes of simplicity.

In carrying out the extraction of the oil with this light liquid fraction the solution is maintained at a pressure sufficient tomaintain the propane liquid at ordinary temperatures. The fraction described above is liquid at ordinary temperatures at a pressure of about pounds per square inch. The extraction of the oil from the petroleum at such pressures results in an asphalt substantially free of oil, compound chiefly of bitumen and a solution of oil and wax in the liquid petroleum fraction. The oil dissolved in the liquid propane contains substantially all of the lubricating oil components which are present in the crude oil and in substantially the same form as they exist in the original crude 'oil and also the major portion of the wax present in the crude oil.

Before further discussion of this invention it will be best to deflne a' new term which we have found useful in identifying the oils of our invention. Curve C of Fig. 1 represents a typical oil which has been extracted with propane from oil containing asphalt and wax. This curve has a slope intermediate between curve A and curve B, i. e., a true paraflin base bright stock, having for example, Saybolt Universal viscosities of 2350 seconds at 100 F. and seconds at 210 F., and a true Western lubricating oil having for example, Saybolt Universal viscosities at 600 seconds at 100 F. and 55 seconds at 210 F. Since the slopes of A and B are characteristic of all oils of like nature the absolute viscosity is immaterial to our present purpose after the lines are once defined. We draw two lines on the chart parallelto curves A and B, respectively, passing through the intersection of curve A with the 100 F. line. These curves are defined as curves A and B. The distance between their intercepts on-the 210 temperature ordinate line is taken as 100. The ratio of the intercept between curves C and B and the intercept between A and B gives the paraffin base characteristics of the oil corresponding to curve C. It will be observed that the curve C shows 51% paraffin base characteristics.

We have discovered that many lubricating oils obtained by extraction with solvents, for instance, propane, from crude oil containing asphalt and wax are composed of oils which are high in paraffin base characteristics, 1. e., have slopes approaching Curve A of Fig. 1, and oils low in paraflin base characteristics, i. e., have slopes approaching Curve B of Fig. 1 and that these oils may be separated into oils which exhibit a low temperature viscosity susceptibility resembling oils produced from non-asphalt containing crude and oils which exhibit a high temperature viscosity susceptibility corresponding to oils produced by' distillation. For convenience we will call the oils which have high-parafiin base characteristics separated into these respective oils by the use of solvent agents which will selectively dissolve out the non-paraffinoid components. We have found that certain solvents have a. selective solvent action for the non-parafiinoicl oils. As solvent agents which will effect this separation we have found liquid sulphur dioxide, mixtures of acetone and benzol, aniline or methyl formate useful. Acetone alone in addition to being an asphalt precipitant also has in some measure the ability to split the oil in the above manner. The use of liquid sulphur dioxide has been found especially valuable as a solvent to separate 'the propane extract into oils which exhibit high paraffin base characteristics and into oils which exhibit low paraffin base characteristics. By subjecting the possess a high temperature viscosity susceptibility. The toppedoil is first dissolved in. liquid propane in.order tojseparatethe oil from the asphalt, after which the ,wax is remove d. The propane solution o f oil is then agitated with treating. quantities. of sulphuricacid after which the sludge formed is allowed to settleout. The propaneis then sep arated from.tl1e' acid treated oil, after which the oil is cooledand treated with liquid sulphur dioxide toresolve it into a portion exhibiting high parafiin base characteristics and a portion exhib-.

iting low-paraffin base characteristics. 7

.. V Vhi1 e' the above method of.v treating the oil with acid appears to be preferable from an engineering standpoint, we have found that by performing this step. in the process subsequent to treatment WithJiquid suIphur dioxide that more effective results are obtained. ,By acid treating the .oil prior to extraction with liquid sulphur, di-i oxide a large portion of the acid is consumed in removing from the oil unsaturated bodies which are easily removable with liquid sulphur dioxide. By treating theoil with acid subsequent to extractionw'ith liquid sulphur dioxidethe acid.

utilized in such treatment is free to act upon those undesirable bodies present in the oil which are not removable by liquid sulphur dioxide. Thus by acid treating subsequent to extraction with sulphur dioxide we are able to obtain a more ECO:-

nomical use of acid and a more effective removal of undesirable bodies present in the oil.

One of the desirable qualities of a lubricating oil is a low Conradson carbon value. According to the United States Government Department of Commerce, Bureau of Mines Technical paper 323B, page 86, thisvalue throws some light upon the relative carbon forming properties of an oil. Oils which possess a low value have less tendency to cause carbon deposition in in-' ternal combustion. motors during use than do oils which possess a high value. In general, lubricating oils produced by the ordinary distillation processes from crudes containing asphalt exhibit a low Conradson carbon value whereas lubricating oils .produced from paraifin base.

crudes exhibits. high valuea 7 It is one of the characteristics, of the lubricating oil produced by our process that it posses,-

ses a low Conradson carbon value. In Table I Conradson carbon values are shown for a typical. parafiin base, lubricating oil, a. typical asphaltic base lubricating oil by our process.

" "TABLEI" "Conradson carbon values Another desirable quality of lubricating oil is a high resistance towards oxidation. In general oils which oxidize less rapidly are to be preferred. Lubricating oils produced from paraffin base crudes have less tendency to oxidize than lubricating oils produced by the distillation of asphalt base crudes. It is one of the charand atypical oil produced acteristics of the oil produced by our process from asphalt base crudes containing wax that it possesses a low oxidation .value.

-One of the methods used to' determine the oxidation value of an oil is to be found in the v Proceedings of the American Society of Testing Materials, Volume 24, Part II of l924, page 964, and is sometimes known as the Slighmethod. In Table II'there is shown a comparison of the oxidation values of a lubricating oil produced from paraflin base crude, a lubricating oil produced by our process from asphalt base crudes containing wax, and a lubricating oil produced by the d stillation of asphaltbase crude:

TABLE'II Sligh ,oridation values 7 Sligh oxidation values Paraflin base lubricating: oil produced from Pennsylvania crude 5.0 Asphaltic base lubricating oil produced by our process from California crude 4.0 Asphaltic base lubricating oil produced from California crud e 40.0

Generally stated. it is the object of our invention toisolate from crude oil those oils having characteristics which impart to it the low temperature viscosity susceptibility typical of paraffin baseoil.

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 parafiinoid from the non-paraifinoid components of the'asphalt containing crude oils.

It is more particularly an object of our invention to isolate from asphalt containing'oils'those lubricating oil components which we call paraffinoid and whichresemble the lubricating oils produced from petroleum crudes substantially free of asphalt but to conserve those peculiar properties of asphalt crudes which impart to the lubricating Oilsobtained therefrom a relatively low Conradsoncarbon value as compared with oils produced from paraflin base'crudes.

It is-a further object of our invention to precipitate asphalt from an oil containing asphalt with'liquid propane and thereafter to extract oil with liquid sulphur dioxide with an end in view of obtaining an oil'relatively insoluble in liquid sulphur dioxide'and which is free fromasphalt and which has characteristics resemblingoils' produced from'c'rudes substantially free'ot asphalt.

-It i'sa' further object of our invention to isolate from'asphalt containingoil those lubricating oils which exhibit a relatively low viscosity temperature susceptibility and which passes a' relatively low Conradson carbon value.

It is a further object'of our invention to separate oil and wax from asphalt bearing crude by the use of liquid propane, to separate the wax from the oil, to resolve the oil into a portion having non-paraflinoid characteristics and a portion having parafiinoid characteristics and to treat the latter oil with sulphuric acid for the purpose of removing further impurities.

It is a further object of our invention to proby referring to the drawings.

Fig. 1 is a set of curves representing viscosity temperature relationships of an oil produced by extraction from an asphalt containing oil.

Fig. 2 is a set of curves representing tempera ture viscosity relationships of an oil produced by treatment of the oil shown in Fig. 1 toremove fractions which increase its temperature viscosity susceptibility.

Fig. 3 is a schematic arrangement of one form of the apparatus in which our process may be carried out.

Fig. 4 is a schematic arrangement of another form of the apparatus in which our process may be carried out.

Referring more particularly to Fig. 3, the crude oil from which all of the gasoline, kerosene and gas oil have been removed in tank 1 is withdrawn through valve 2 and sent by means of pump 3 to line 4 where it meets a stream of liquid propane coming from storage tank 11 through valve 12, pump 13 and line 14. The mixture of topped crude and liquid propane passes into chiller 5 where the mass is'cooled by allowing a portion of the liquid propane to vaporize under reduced pressure through valve 6 into line '1. Thevaporized propane in line 1 is compressed by compressor 8. and sent to condenser 9 where it is liquefied and passes by means of line 10 to propane storage tank 11.

The cooled mass of topped crude and liquid propane in chiller 5 passes by means of line to agitator 16 where it is thoroughly mixed, after whlch'it passes by means of line 17 to decanter 18 where the asphalt settles out.

The asphalt in decanter 18 is removed through valve 19 and sent by pump 20 through line 21 to heater 22 where the temperature of the mass is raised sufficiently to vaporize all the propane and moisture present. passes by means oi line 23 into separator 24 where the asphalt separates out and is removed through valve 25 and line 26 to storage tank 27. The mixture of water vapor and propane passes from separator 24 through line 28 to condenser 29' -where the water vapor is condensed. The mixture of water and propane vapor passes from condenser 29 to separator 30 where the water is separated out and is removed through valve 31 and line 32. The propane vapor in separator 30 passes by means of line 33 to compressor 34 where it is compressed and sent by means of line 33' to condenser 9 where it is liquefied and. passes through line 10 to storage tank 11.

The propane solution or oil in decanter 18 is withdrawn through line 35 and passes into chiller 36 where the temperature of the mass is lowered to a point suflicient to cause thorough wax precipitation by allowing a portion of the propane present in chiller 36 to vaporize and reduce pressure through valve 37 into line 38. The propane vapor in line 38 is compressed by compressor 39 and sent through line 38 to condenser 9 where it is liquefied and passes by means of line 10 to storage tank 11. r

The cooled mass in chiller 36 is withdrawn through valve 40 and line 41 whereafter it is sent by pump 42 to a dewaxing stage which may consist in centrifuging, filtering and cold settling the chilled mass to remove the wax. The de- -valve 53 and sent The heated mass then' waxed oil dissolved in liquid propane emerges from the dewaxing stage into line 44 where it is mixed with sulphuric acid coming from tank 45 through valve 46, line 47, compressor 48 and line 47'. The mixture of oil and acid then passes into agitator 49 where they are thoroughly mixed after which they pass into decanter 51'where the sludge is allowed to settle out.

The sludge in decanter 51 is removedthrough by means of pump 54 through line 55 to heater 56 where the temperature of the mass is raised sufliciently to vaporize the propane. The heated mass then passes by means of line 57 to separator 58 where the sludge separates out and is withdrawn through valve 59 and line 60. The propane vapor passes from separator 58 through line 61 to scrubbing tower 62 where it is contacted with liquid caustic soda to rem'ove any sulphur dioxide present. The scrubbed propane passes from tower 62 through valve 66, line 6'1, compressor 68, line 6'1 to condenser 9 where it is liquefied and passes by means of line 10 to storage tank 11.

The acid treated oil dissolved'in propane in decanter 51 passes by means of line 52 to clay tower 125 where any remaining sludge is removed. The propane solution of treated oil then passes from tower 104 by means of line 69 to evaporator'lfl where the propane present is vaporized with the aid of steam introduced through closed steam coil 74. The propane vaporpasses from evaporator '70 through valve 71 into line- '12 thence to compressor 73.. where it is compressed and sent by means of line 72 to condenser '9 where it is liquefied and passes by means of line 10 to storage tank 11. The propane free oil in evaporator is withdrawn through valve '15 and passes through cooler 76 where the temperature is lowered sufliciently for extraction of the sulphur dioxide. The cooled oil passes from cooler '16 to pump 7'7 which forces it through line 78 into the lower zone of extraction column 104.' Liquid sulphur dioxide from tank 79 is withdrawn through valve 80 into line 81 and is forced by pump 82 through line 81' into the upper zone or extraction column 104. Due to the difference in specific gravity of oil introduced into the lower zone of extraction column 104 and the sulphur dioxide introduced into the upper zoneof extraction column, these two liquids tend to separate. As the heavy liquid sulphur dioxide passes down through the ascending column of oil it dissolves certain constituents present which are removed in the form of a sulphur dioxide solution through valve 94 into line 95 from which it passes into evaporator-96 wherethe sulphur dioxide present is removed with the aid of steam introduced in closed steam coil 105 and passes through valve 9'? into line 90 and thence to compressor 101 where it is compressed and passes by means of line 90' to condenser 102 where it is liquefied and passes by means of line 103 to sulphur dioxide storage 79.

The ascending column of oil in column 104 from which there has been removed the sulphur dioxide soluble constituents passes through valve 83 and line 84 into auxiliary settling chamber 85 where any remaining liquid sulphur dioxide settles out. The settled oil from chamber 85 passes through line 8'7 into evaporator 88 wherethe sulphur dioxide present is vaporized by aid of steam introduced into closed steam coil 106 and passes through valve 89 to line 90 and thence to compressor 101 where it is compressed and sent through line 90 to condenser 102 where it is liquefied and passes by means of line 103 to sulphur tank 11 through valve 12, pump 13 and line 14.

The mixture of topped oil and propane passes into chiller where the temperature of'the mass is lowered by allowing a portion of the propane to vaporize at a. reduced pressure through ,valve 6 into line 7 from whence it passes to compressor 8 where it is compressedand passes to condenser 9 where it is liquefied and passes by meansof line 10 to propane storage tank 11.

The cooled mixture of topped oil and liquid propane passes from chiller 5 through line to agitator 16 where the mass is thoroughly agitated after which it passes by means of line 17 to decanter 18 where the asphalt is allowed to separate out.

The asphalt in decanter 18 is withdrawn through valve 19 and sent by means of pump 20 through line 21 to heater22 where the temperature of the mass is raised sufficiently to vaporize the propane and moisture present. The heated mass then passes by means of line 23 into separator 24 where the asphalt separates out and is withdrawn through valve 25 and line 26 into storage tank 27. .The mixture of propane vapor and water vapor passes by means of line 28 through condenser 29 where any moisture present is condensed. The mixture of water and propane vapor passes into separator 30 where the water is removed through valve 31 and line 32. The propane vapor in separator 30 passes by means of line 33 to compressor 34 where it is compressed and passes bymeans of line 33' to condenser 9 where it is liquefied and passes by means of line 10 'to storage tank 11. v

The propane solution of oil in decanter 18 passes through line 35 tochiller 36 where the temperature, of the mass is lowered sufllciently to cause a thorough precipitation 01' the wax by allowing a portion of. the propane present to vaporize under reduced pressure through valve 37 into line, 38 from whence it passes to compressor- 39 where it is compressed and sent through line 38' to condenser 9 where it is liquefled and passes by means of line 10 into storage tank 11. The cooled mass in chiller 36 is withdrawn through valve 40 and line 41 and sent by means of pump 42 through the dewaxing-stage 43 which may consist of centrifuging, filtering or cold settling to remove the wax present. The dewaxed oil emerges from the dewaxing stage 43 through line 44 and passes into evaporator 70 where the propane present is vaporized by theaid of heat introduced through closed steam coil 74. The vaporized propane passes from evaporator 70 through valve 71 and compressor 73 where it is compressed and is sent by means of line 72 and line 38' to condenser 9 where it'is liquefied and passes by means of line 10 to storage tank 11. The propane free oil in evaporator '70 is withdrawn through valve 75 and line 75' and sent by means of pump 77 through cooler '16 where the temperatureof theoil is lowered sufliciently before extraction with sulphur dioxide. The cooled oil in cooler 76 passes by meansvof line 78 into the lower zone of extraction column 104. Liquid sulphur dioxide from storage tank '79 is withdrawn through valve 80 and line 81 to pump 82 which sends it through line 81' -,to the upper zone of extraction column 104. Due to the difference in specific gravity of the sulphur dioxide introduced into the upper zone of the extraction col-" umn and the oil introduced into the lower zone of the extraction column, these two liquids tend to separate. The heavy liquid sulphur dioxide passing down through extraction column 104 removes certain components from the oil present in the column in the form of a-sulphur dioxide] solution. This solution is withdrawn through valve 94 into line- 95 and passes into evaporator 96 where the sulphur dioxide present is vaporized with the aid of steam introduced through closed coil 105. The vaporized sulphur dioxide passes from evaporator 96 through valve 97 into line 90 and thence to compressor 101 where it. is compressed and sent by means of line 90 to condenser 102 where it is liquefied and. passes by means of line 103 to sulphur dioxide storage tank 79. The sulphur dioxide tree oil in evaporator 96 is withdrawn through valve 98 and passes by means of line 99 to storage tank 100.

The ascending column or oil in extraction col-. umn 104 from which the sulphur dioxide soluble components have been removed is withdrawn through valve 83 into line 84 from whence it passes into auxiliary settling chamber where any remaining liquid sulphur dioxide is settled out. The settled oil in chamber 85 passes through line 87 into evaporator 88 where the sulphur dioxide present is vaporized with the aid of steam introduced through closed coil 106. The sulphur dioxide vapor in vaporizer 88 passes by means of valve'89 into line and thence to compressor 101 where it is compresed and passes by means of line 90' to condenser 102 where it is liquefied and passes by means of line 103 to liquid sulphur dioxide storage 79. The sulphur dioxide free oil in vaporizer 88 is withdrawn through valve 91, and sent by means of line 92 to pump 114 which forces it into line 115 where it is re-dissolved by liquid propane coming from storage tank 11 through valve 117, pump 118, line 120. The propane solution or oil is then mixed with sulphur dioxide coming from tank 45 through valve 46, line 47. pump 48 and line 4'7. The mixture. of asphalt and oil, in line 115 passes into agitator 49 where it is thoroughly mixed, after which it passes into separator 51 where the sludge is allowed to separate out.

The sludge in separator 51 is withdrawn through valve 53 and sent by means of pump 54 through line 55 to heater 56 where the tem perature of the mass is raised sufficiently to vaporize the propane present. The heated mass passes from heater 56 through line 5'? to separator 58 where the sludge separates out and is withdrawn through valve 59 and line 60 and sent to s ludgetank 113. The propane vapor in separator 58 passes by meansof line 61 through scrubbing tower 62 "where it is contacted with liquid caustic soda to remove any sulphur dioxide present. The scrubbed propane passes from tower 62 through line 67 to compressor 68 where it is compressed and sent by means of line 67" and line 33'- to condenser 9 where it is liquefied and passes'by means of line 10 to storage tank 11.

The acid treated oil dissolved in the propane is withdrawn from settling chamber 51 through line 52 and sent through clay" tower which removes any remaining sludge present, after which it passes by means of line 69 to evaporator 119 where the propane present .is vaporized with The topped oil in tank 1 of Fig. 3'at a 'temperature approximating 200 F. is mixed with liquid propane and cooled by allowing a portion of the propane present to vaporize until a temperature of about 120 F. is attained, after which the'mixture of residual oil and propane is mixed in agitator 17. The thoroughly agitated mass passes into decanter 18 where the propane solution of oil and wax is separated from the undissolved asphalt. This oil dissolved in liquid propane which is a mixture of paraffinoid and non-paraffinoid oils possessing about 54% ,parafiin base characteristics is chilled sufficiently to cause the wax present to precipitate out by allowing a further portion of the propane present to vaporize under reduced pressure. The precipitated wax is removed from the solvent solution of oil by such means as cold settling, centrifuging, or filter pressing. The oil, substantially free of wax and asphalt dissolved in solvent, is next treated with sulphuric acid introduced from tank 45. The result of this treatment is to remove further quantities of undesirable bodies present in the oil which tend to give the finished product an increased viscosity temperature susceptibility. After treatment with sulphuric acid the oil is separated from the solvent and then extracted.

with liquid sulphur dioxide for the purpose of separating the parafilnoid from the non-parafilnoid constituents. Curve C of Fig. 2 is representative of an oil obtained by our process and. exhibits 62% paraflin base characteristics. Ashas been explained in the foregoing description, it has been found advisable in some cases-to perform the acid treatment subsequent to treatment with liquid sulphur dioxide. The process as set forth in Fig. 4 is illustrative of this mode of operation.

The foregoing exemplary description is merely illustrative of a preferred mode of carrying out our invention and is not to be taken as limiting, as many variations may be made within the scope of the following claims by a person skilled in the art without departing from the spirit thereof.

We claim:

1. A method for the treatment of oil containing asphalt and wax which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent, to separate asphalt, removing the asphalt from the oil and wax dissolved in said solvent, chilling the solvent solution of oil and wax to precipitate wax, separating the wax from the oil and solvent, separating the solvent from the oil, extracting said substantially asphalt and wax free oil with a selective solvent to form a parafiinoid fraction and a non-paraifinoid fraction and separating said fractions.

2. A method for the treatment of oil containing asphalt and wax which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent under superatmospheric pressure to separate asphalt, removing the asphalt from the oil and wax dissolved in said solvent, releasing the pressure on said oil and.

wax dissolved in said solvent and vaporizing a portion of said solvent to chill'the'oil and precipitate wax, separating the precipitated wax from the oil and remaining solvent, removing the remaining solvent from the oil, extracting the substantially asphalt and wax free oil with a selective solvent to form a paraflinoid fraction and a non-parafiinoid fraction and separating said fractions.

3. A process as in claim 1 in which the'selective solvent is sulphur dioxide. Y

4. A method for the treatment of oil containing asphalt and wax which comprises commin-' gling said 011 with a liquefied normally gaseous hydrocarbon solvent containing a major portion of propane to separate asphalt. removing the asphalt'from the oil and wax dissolved in said solvent, cooling the solvent solution of, oil and wax to precipitate wax, separating the precipitated wax from the oil and solvent, removing the solvent from the substantially asphalt and wax free oil, extracting the substantially asphalt and wax free oilwith a selective solvent to form a parafiinoid fraction and a non-parafiinoid fraction and separating said fractions.

5. A process as in claim 4 in which the selective solvent is sulphur dioxide.

- 6. A method for the treatment of oil containing asphalt and wax which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent to separate asphalt, separating the asphalt from the oil and wax dissolved in said solvent, chemically treating the oil and wax dissolved in said solvent, chilling the treated solution of asphalt and wax to precipitate wax, separating the solvent from the substantially asphalt and wax free oil, extracting the substantially asphalt and wax freev oil with a selective solvent to form a parafflnoid fraction and a nonparafiin'oid fraction and separating said fractions.

'1. A method for the treatment of oil containing asphalt and wax which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent containing a major portion of propane to separate asphalt, separating the asphalt from the oil and wax dissolved in said solvent, chilling the solvent solution of oil and wax to precipitate. wax, separating the precipitated wax from the oil and solvent, chemically treating the substantially asphalt and wax free 011 dissolved in said solvent, separating the solvent from the'substantially asphalt and wax free oil, extracting the substantially asphalt and wax free 011 with a selective solvent to form a parafllnoid fraction and a non-parafiinoid fraction and separating said fractions.

8. A method for the treatment of oil containing asphalt and wax which comprises commingling said oil under superatmospheric pressure with a liquefied normally gaseous hydrocarbon solvent, containing a major portion of; propane. to separate asphalt, separating the asphalt from the oil and wax dissolved in said solvent releasing the pressure on the solvent solution, of oil and vaporizing a portion of the solvent to chill the 'oil and precipitate wax,- separating the precipitated wax from the oil and remaining solvent, chemically treating the substantially asphalt and wax free oil dissolved in the remaining solvent, removing the remaining solvent from the oil, extracting the substantially asphalt and wax free oil with a selective solvent to form a parafiinoid and a non-paraflinoid fraction and separating said fractions.

9. A method for the treatment of oil containing asphalt and wax which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent to precipitate asphalt, separating the precipitated asphalt from the oil and wax dissolved in said solvent, chilling the solvent solution of oil and wax to precipitate wax, separating the wax from the oil and solvent, removing the solvent from the substantially asphalt and wax free oil, extracting said substantially asphalt and wax tree oil with a selective solvent to form a parafllnoid fraction and a nonparafiinoid fraction, separating said fractions and chemically treating the paraflinoid fraction.

10 A process as in claim 9 in which the chemical treatment is carried out in the presence of a liquefied normally gaseous hydrocarbon solvent.

11. A method for the treatment of oil contain- Patent No. 1,988, 712

ing asphalt and wax which comprises commingling said oil under superatmospheric pressure with a liquefied normally gaseous hydrocarbon solvent containing a major portion of hydrocarbons of less than four carbon atoms to separate asphalt, separating the asphalt from the oil and wax dissolved in said solvent, releasing the pressure on said solvent solution of oil and wax and vaporizing a portion of the solvent to chill the oil and precipitate wax, separating the precipitated wax from the oil dissolved in the remaining solvent, removing the remaining solvent from the oil, extracting the substantially asphalt and wax free oil with a selective solvent to form a parafilnoid fracton and a non-parafllnoid frac- January 22, 1935.

- ULRIC B. BRAY, ET AL.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correct after "the" in the Patent Office.

insert the word same; page 6, reference claim number "1" read 2; and that the said Letters with these corrections therein that the same may con line 11,

d olumn, sewn 6 Patent should be read Signed and sealed this 9th day of April, A. D. 1935.

Leslie Frazer.

Acting Commissioner of Patents.

form to the record of the case on" lncnlnfiwn ,Monsanto. .l c t g n w, n 3/ 3 7 CERTIFICATE or CRRECTION.

' .Pa e 1, second column, line 1. [011 as follows g claim 3 for the I 9. A method for the treatment of oil containing asphalt and wax which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent to precipitate asphalt, separating the precipitated asphalt from the oil and wax dissolved in said solvent, chilling the solvent solution of oil and wax to precipitate wax, separating the wax from the oil and solvent, removing the solvent from the substantially asphalt and wax free oil, extracting said substantially asphalt and wax tree oil with a selective solvent to form a parafllnoid fraction and a nonparafiinoid fraction, separating said fractions and chemically treating the paraflinoid fraction.

10 A process as in claim 9 in which the chemical treatment is carried out in the presence of a liquefied normally gaseous hydrocarbon solvent.

11. A method for the treatment of oil contain- Patent No. 1,988, 712

ing asphalt and wax which comprises commingling said oil under superatmospheric pressure with a liquefied normally gaseous hydrocarbon solvent containing a major portion of hydrocarbons of less than four carbon atoms to separate asphalt, separating the asphalt from the oil and wax dissolved in said solvent, releasing the pressure on said solvent solution of oil and wax and vaporizing a portion of the solvent to chill the oil and precipitate wax, separating the precipitated wax from the oil dissolved in the remaining solvent, removing the remaining solvent from the oil, extracting the substantially asphalt and wax free oil with a selective solvent to form a parafilnoid fracton and a non-parafllnoid frac- January 22, 1935.

- ULRIC B. BRAY, ET AL.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correct after "the" in the Patent Office.

insert the word same; page 6, reference claim number "1" read 2; and that the said Letters with these corrections therein that the same may con line 11,

d olumn, sewn 6 Patent should be read Signed and sealed this 9th day of April, A. D. 1935.

Leslie Frazer.

Acting Commissioner of Patents.

form to the record of the case on" lncnlnfiwn ,Monsanto. .l c t g n w, n 3/ 3 7 CERTIFICATE or CRRECTION.

' .Pa e 1, second column, line 1. [011 as follows g claim 3 for the I

Images