US2316395A - Process for production of lubricating oil - Google Patents

Description

April 13,1943 U. B. BRAY ETAL PROCESS FOR PRODUCTION OF LUBRICATING OIL' original Fi1ed Aug. 4,'1931 v muy Y. m W E ma M VE m m@ T Patented Apr. 13, 1943 STATES TENT OFFICE PROCESS FOR PRODUCTION OF LUBRICATIN G OIL Original application Au 555,018. Divided and gust 4, 1931, Serial No. this application February 19, 1935, lSerial No. 7,268

(Cl. ISG-13) 4 Claims.

This invention relates to a method and apparatus for treating petroleum to produce lubricating oil, and is a division of our copending application Serial No. 555,018, iled August 4, Y1931.

`Subject matter disclosed herein but not claimed is claimed in the following copending applications and patents: Serial No. 615,254,1iled August 22, 1933 claiming separation of oil into fractions with a selective solvent and/or dewaxing with a selective solvent and a diluent; lSerial No. 709,836, filed February 5, 1934 claiming separation of asphalt from oil at elevated temperature with a liqueed normally gaseous hydrocarbon; Serial No. 9,314, filed March 4, 1935 claiming selective solvent extraction of a partially deasphalted oil; Patent No. 1,988,711 claiming deasphalting with solvents followed by solvent extraction of the deasphalted oil; Patent No. 1,988,712 claiming `deasphalting and dewaxing with solvents in conjunction with selective solvent extraction of the oil; Patent No. 2,006,092' claiming extraction of oil with a selective solvent in the presence of a liquefied normally gaseous hydrocarbon; Patent No. 2,006,093 claiming extraction of oil With propane and a selective solvent and also extraction of oil containing asphalt with a selective solvent and a low boiling hydrocarbon; Patent No. 2,006,- 094 claiming selective solvent extraction of an oil in the presence of a liquefied normally gaseous hydrocarbon and dewaxing; Patent No. 2,006,095 claiming dewaxing oil in the presence of a liqueed normally gaseous hydrocarbon and selective solvent extraction of the dewaxed oil; Patent No. 2,006,096 claiming acid treating oil diluted with a liqueiied normally gaseous hydrocarbon and selectivev solvent extraction; and Patent No. 2,006,087 claiming extracting oil with a liquefied normally gaseous hydrocarbon and a selective solvent and acid treating the oil recovered in the liqueed normally gaseous hydrocarbon.

One of the distinctive characteristics of a lubricating oil is its viscosity. For many purposes lubricants are preferred which exhibit a minimum variation in lviscosity with variations in temperature, i. e., have low viscosity temperaturev susceptibility. It is generally known that the viscosity of lubricating oil produced from Western crude, such as California naphthene base crudes, lthat is, crude containing asphalt varies more with change in temperature than do lubricating oils produced from paran base crudes. That is, if two such oils have the same viscosity at 100 F., the Western oil will have a much lower viscosity at 210 F. than will the paraliin base-oil. This change in 'viscosity' with temperature is sometimes called the temperature susceptibility of an oil. It is one of the characteristics of Western lubricating oils that they are distillates, that is, are vaporized from crude oil and condensed. Lubricating oils produced Afrom paraffin base oils, containing substantially no asphalt, are generally produced by rst distilling lig-ht oils overhead, including the kerosene and gas-oil Aand also taking overhead light lubricating oils called neutrals having a viscosity in the neighborhood of 10U-200 seconds, Elaybolt -Universalfat 100 F., leaving an undistilled residue termed bright stock. The oils of various viscosity are made by blending these neutrals and bright stock in any desired proportion -to obtain the desired viscosity.

It has been observed by one of us that many oils containing asphalt and wax'aremixtures of hydrocarbons analogous both to the `hydrocarbons present in parafn base oils and those present in asphalt 'base oils. It has further been observed by one of us that during the heating vof an oil containing asphalt, the asphalt apparently induces certain chemical and perhapscertain physical reactions at relatively low temperatures which tend to destroy the linherent low viscosity temperature susceptibility of the lubricating oil fractions. This apparent catalytic phenomena seems to explain the observed changes although we do not wish to be understood as being bound by this theory. It has been observed that these temperatures at which the changes appear Vare below the vaporizing temperatures lin batch distillation (vacuum or steam) ofthelubricatingoil fractions which have Saybolt Universal viscosities above 40G-500 seconds at y100 F. Itis Saft to say that no oil containing asphalt'can 'be topped to the point where fractions above 40G-500 seconds, Saybolt Universal viscosity Aat 100i F. are vaporized vwithout a degeneration ofthose characteristics of the paraiiin hydrocarbons which impart to the cil a low Atempearture viscosity susceptibility. During the distillation of the heavy oils in the presence of asphalt some change in molecular 4structure orconfiguration takes place which isa-ttendedbyga Change ofviscosity 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.' 4,166,189.

In order` to preserve the lnherentcharacteristics of the lubricating oil components vofcrude oil containing asphalt which are impaired by dis-- tillatlon methods as previously described. vvWe 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 butane4 and 1.17% normal butane is satisfactory. 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 to maintain the Y propane liquid at ordinary temperatures. The fraction described above is liquid at ordinary temperatures at a pressure of about 125 pounds per square inch. The extraction of the oil from the petroleum at such pressures results in an asphalt substantially free of oil consisting chiefly of pure bitumen and a solution of oil and wax in the liquid petroleum fractions. 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.

, 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 have a relatively high temperature viscosity susceptibility and oils -which have a relatively low temperature viscosity susceptibility and that these oils may be separatledinto 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 exhibit a low temperature viscosity susceptibility parainoid and those which exhibit a high temperature viscosity susceptibility and resemble the Western lubricating oil distillates non-paraffinoid. The propane extract which consists of such a mixture of parallinoid and non-paramnoid oils may be separated into these respective oils by the use of solvent agents which Will selectively dissolve out the non-parainoid components. We have found that certain solvents have a selective solvent action for the non-parafnoid 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 low temperature viscosity susceptibility and into oils which exhibit high temperature viscosity susceptibility.

As the propane extract from the crude oil consists of a mixture of wax and oil normally solid at ordinary temperatures, it cannot be separated into its para'inoid and non-parafnoid components by the use of sulphur dioxide, without considerable difficulty, unless dissolved in a carrying medium. We have found it advantageous to carry out the extraction of the Wax oil mixture with sulphur dioxide in the presence of the liquid propane used in separating the asphalt. The wax oil mixture is dissolved in liquid propane after which it is extracted with liquid sulphur dioxide to remove therefrom the non-parallnoid components. The propane solution of parilianoid oil is then chilled to precipitate the Wax present after which the chilled mass is cold settled, centrifuged, or filtered to separate the wax from the propane solution of oil. By removing the sulphur dioxide soluble bodies from the propane solution of waxy oil prior to the dewaxing operation we are able to obtain a nal product with a lower pour point, i. e., wax content than could be obtained if the sulphur dioxide extraction operation were performed subsequent to wax removal. The sulphur dioxide removes from oil certain bodies present which are good wax solvents and which have a tendency to prevent precipitation of the Wax during the dewaxing operation.

The propane solution of oil recovered from the dewaxing operation substantially free of asphalt and Wax may be further purified by treatment With sulphuric acid. Such treatment removes from the paraffin oil further impurities which were not removed from the oil by the treatment with liquid sulphur dioxide.

Generally stated, it is the object of our invention to isolate from crude oil those oils having characteristics which impart to it the low temperature viscosity susceptibility typical of paraffin 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 paraifinoid from the non-paraftlnoid components of the asphalt containing crude oils.

It is a further object of our invention to separate asphalt from 4an oil containing asphalt, oil and Wax 'by means of a solvent, to separate the Wax and paraffinoid oil from the non-paraflinold oil by means of a second solvent used in the presence of the first solvent, to separate the Wax from the parainoid oil and thereafter to treat the parafnoid oil dissolved in said first solvent with sulphuric acid.

It is a further object of our invention to separate oil and wax from an oil containing asphalt, oil and wax by the use of liquid propane; to separatethe wax and parainoid oil from the nonparamnoid oil by the use of liquid sulphur dioxide in the presence of liquid propane; to separate the wax' from the para'inoid oil and thereafter to treat the paraffinoid oil with sulphuric acid.

The figure is one form of apparatus which we may employ to carry out our process.

Referring more particularly to the figure, the crude which has been distilled to remove Ylight oils'such as gasoline and kerosene and is itself a :residual oil icontaining lubricating fractions, asphalt and wax in' tank I is withdrawn through valve 2 and sent bymeans of pump 3 through line: 4 where it meets a stream of liquid propane coming from tank l through valve II, line I2, pump ||5 and line 2'. ,The mixture of topped crude and liquid propane passes from line 4 to chiller 5 where a portion of the propane is allowed t0 VaDOTZe through Valve 6 land passes by means of line 1 to pump 32 where it is compressed and sent to condenser 8 wherel it is liquefied and sent by means of line 9 to storage tank I0. The vaporization of the propane in chiller 5 causes the temperature of the mass therein to be lowered. The cool mass from chiller 5 passes by means of line |3 to agitator I4 where it is thoroughly mixed and sent by means of line I5 to decanter I6 where the asphalt is allowed to settle out.

The asphalt is withdrawn from decanter I6 through valve |1 and sent by means of pump I8 through line I9 to heater 20 where the propane and moisture are vaporized. The heated mass passes from heater through line 2| to separator 22 where the asphalt separates from the vapors and is withdrawn through valve 23 and line 24 in the storage tank 25. The vapors in separator 22 are withdrawn through line 26 into condenser 21 where the water vapor present is condensed. The condensed water and propane vapor pass into separator 28 where the water separates and is withdrawn through valve 29 and line 30. Propane vapor passes from separator 28 through line 3| to compressor ||3 thence to condenser 8 where it is liqueed and passes by means of line 9 to storage tank I0.

The solution of cil in liquid propane in decanter vI6 is withdrawn through line 33 and sent to chiller 34. A portion of the propane present is allowed to vaporize by opening valve and allowing the vapors to pass through line 36 to compressor |I6 where it is compressed and sent to condenser 8 and is liquefied, thereafter being sent to storage tank I0. The vapor-ization of the propane in chiller 34 cools the mass which is thereafter withdrawn through valve 31, line 38 and sent by means of pump 39 through line 40 to the lower zone of extraction column 4I. Liquid sulphur dioxide from tank 42 is withdrawn through valve 43 and sent by means of pump 44 through line 45 to the upper zone of extraction column 4|. Due to the difference in specific gravity of the oil introduced through the lower zone of the extraction column and the liquid sulphur dioxide introduced into the upper zone of the extraction column, these two liquids tend to separate. As the liquid sulphur dioxide descends through the extraction column it dissolves certain components present in the oil.

The solution of liquid sulphur dioxide and oil is removed from the extraction column 4I through the valve 46 and sent by means of line 41 to vaporizer |05 where the sulphur dioxide is vaporized by 'aid of steam introduced through closed coil |0| and passes through line |06 to compressor |01 where it is compressed and sent through line |08 to condenser |09 where it is liquefied and sent to storage tank 42. Sulphur dioxide free oil in vaporizer |05 is withdrawn through valve |02 and sent through line |03 to tank |04.

The ascending column of oil in extraction column 4I, from which the liquid sulphur dioxide soluble components have been removed, passes through valve 48 to line49 to auxiliary separator 50 where any remaining liquid sulphur dioxide is settled out.` A clear solution of oil isiwithdrawn from auxiliary separator v50 through line 52 where it may be mixed with a further quantity of liquid propane coming from storage tank I0 through Valve 53, pump |I4 and line 54. The solution. of Ioil and propane carrying a small quantity of sulphur dioxide passes into chiller 55 where a' portion of propane is allowed to vaporize by opening 4valve 6|. The vaporized propane contaminated with sulphur dioxide, passes through line 62 to compressor where it is compressed and sent through line 88 to con denser 89 where both the sulphur dioxide and the propane are condensed and pass by means of line H0 to separator 90 where these two materi-als separate due to their great diilerence in specific gravity. The liquid propane in separator 90 is withdrawn through valve 9| and sent by means of pump 93 through line 96 to storage tank I0. The liquid sulphur dioxide in separator 90 is withdrawn through valve 92 and sent by means of pump 94 `through line 95 to storage tank 42. The vaporization of the propane in chiller 55 cools the remaining solution of oil present which passes out through valve 59 and line 51 to pump 58 which forces it through lter press 59 where the precipitated wax is removed through line 60.

The wax-free oil from filter press 59 passes through line 61 where it meets a stream of sulphuric acid coming from tank 63 through valve 64, line 65 and pump 66. The mixture of acid and oil passes from line 61 through agitator 68 where the. massis thoroughly agitated, after which it passes thro-ugh line 69 to separator 10 where the sludge is allowed to vsettle out. The sludge in separator 10 is withdrawn through valve 15, line 16, to pump 'I1 which forces it through line 18 to heater 19 where the mass is heated. sufficiently to vaporize the propane present. The heated mass passes from heater 'i9 through line 80 to separator 6I where the sludge separates from the propane and is withdrawn through valve 82 and sent through line 83 to storage 84. The propane vapor is vwithdrawn from separator 8| through line 85 to compressor |I2 where it is compressed and vsent by means of line 88'to condenser 89 where it is liqueed and sent by means of line I I 0 to separator 90 where it is separated from any liquid sulphur dioxide and sent by means of valve 9|, pump 93, line 96 to storage tank I0. The liquid sulphur dioxide in separator 90 is withdrawn through valve 92 and sent by pump 94 to sulphur dioxide storage tank 42.

The acid treated oil in separator 10, dissolved in propane carrying varying amounts of sulphur dioxide, is withdrawn through line 1| and passed through clay tower 12 where any remaining solution is separated out. The fraction of oil leaving clay tower 12 passes by means of line 13 to evaporator 'I4 Where the propane and sulphur dioxide present are vaporized Iby aid of steam introduced through closed coil 91 and are sent by means of line 86 to compressor 81 where they are compressed and sent by means of line 88 to condenser 89 where they are liqueed and sent by means of line I I0 to separator 90. Liquid propane in separator 90 is returned to storage tank I0 through valve 9|, pump 93, and line 96. The sulphur dioxide in separator 90 is returned to storage tank 42 through valve 92, pump 94 and line 95. The oil in evaporator 14 which is free from propane and sulphur dioxide is removed through valve 98 and sent by means of line 99 to refined oil tank |00.

As illustrative of the operation of our process for one type of oil and Without intending to limit our invention, water free residual oil in tank l of the figure at a temperature of about 200 F. is mixed with liquid propane and cooled by allowing a portion of ,the propane to vaporize under reduced pressure until the temperature of the topped oil and propane is about 120 F. after which it is thoroughly mixed in agitator I4. The thoroughly agitated mass is then passed into decanter I6 where the propane solution of lubricating oil and Wax is separated from the undssolved asphalt. This oil dissolved in liquid propane contains a mixture of paraffinoid and non-paramiloid components. By subjecting this mixture to the selective solvent action of liquid sulphur dioxide in the presence of liquid propane it is possible to resolve the mixture into a portion of a non-parafnoid nature soluble in liquid sulphur dioxide and a portion of a paraffinoid nature soluble in liquid propane. The Wax present in the mixture being more soluble in the liquid propane than in the liquid sulphur dioxide remains in solution in the former. This mixture of paraflinoid oil and Wax dissolved in liquid propane is then chilled to a point suiiicient to cause precipitation of the wax, after which the chilled mass is filtered, centrifuged or cold settled to remove the wax. 'I he wax-free solution of parainnoid oil dissolved in the liquid propane is then treated with sulphuric acid to remove further undesirable bodies present, after which the solution formed is settled out and the propane removed by distillation from the rened oil.

The foregoing exemplary description is merely illustrative of a preferred mode of carrying out our invention and is not to Abe 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:

, l. A process for the production of lubricating oil from oil containing wax which comprises commingling said oil with a liquid having a selective solvent action as between parainic and nonparaflinic fractions of the oil and a relatively less selective solvent liquid to form an extract' phase comprising selective solvent and non-paralnic fractions and a raffinate Phase comprising selective solvent, less selective solvent and parafnic fractions including wax, separating said phases, cooling the raffinate phase to separate wax and removing the wax from the raffinate phase.

2. A process for the separation of mineral oil into fractions comprising commingling said oil with a selective solvent as between paranic and non-paraiiinic constituents of the oil, and ethyl ether to form a raffinate phase comprising paraffinic constituents of the oil and ether and an extract phase comprising non-parafnic constituents of the oil and selective solvent, and separating said phases.

3. In the manufacture of lubricating oil from mixed base mineral oil, the method of separating therefrom fractions of differing viscosity index comprising extracting the oil with a solvent having a selective action substantially of the character of that of sulphur'dioxide as' between said constituents of differing viscosity index, in the presence of ethyl ether, said solvents being adapted to form a 2-layer liquid system with the oil whereby the oil is separated into fractions respectively rich in low viscosity index and high viscosity index constituents.

4. The process of manufacturing low cold test high viscosity index lubricating oil from Waxbearing mineral oil which comprises mixing the oil with liquid sulphurdioxide and a modifying solvent having relatively less selective action than sulphur dioxide as between low and high viscosity index constituents of the oil, in such proportions with the oil that the mixture exerts a selective solvent action as between the relatively low viscosity index constituents and the relatively high viscosity index constituents including wax, forming an extract phase comprising low viscosity index constituents and a raffinate phase comprising high viscosity index constituents and wax. separating the extract phase from the raffinate phase, chilling the raffinate phase and separating the Wax hydrocarbons from said chilled raffinate phase.

ULRIC B. BRAY. CLAUDE E. SWIFT.

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