US2006097A - Process for treating oil - Google Patents

Description

June 25, 1935. u. B. BRAY Er AL y PROCESS FOR TREATING OIL Original Filed Aug. 4, 1931 NN W v Nw n o NESS Patented. June 25, 1935 UNITED STATES ,PATENT OFFICE PROCESS FOR TBEATING OIL Ulric B. Bray, Palos Verdes Estates, and Claude E. Swift, Glendale, Calif., assignors to Union Oil Company of California, Los Angeles, Calif., a. corporation of California Original application August 4, 1931, Serial No.

1934, Serial No. 730,214:1

i` scisims.

This invention relates to a method and apparatus for treating petroleum to produce lubricating oil. This invention is a division of our copendihg application, Serial No. 555,018, illed August 4, 1931.

One of the distinctive characteristics of a lubricating oil is its viscosity. For many purposes lubricants are preferred whichy exhibit a minimum variation in viscosity with variations in temperature, i. e., have low viscosity temperature susceptibility. It is generally known that the viscosity of lubricating oil produced from western crude, suchas California naphthene base crudes, that is, crude containing asphalt. varies more with change in temperature than do lubricating oils produced from paramn base crudes. I

That is, if two such oils have the same viscosity at F. the western oil willhave a much lower viscosity at 210 F. than will the paraflin base oil. This change in viscosity with temperature is sometimes called the temperature viscosity susceptibility of an oil. It is one of the characteristics of Western lubricating 'oils that they are 4distillates, that is, are vaporized from crude oil 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 are mixtures of hydrocarbons analogous bothto'the hydrocarbons present in paraiiin base oils Vand those present in asphalt base oils. It has further been observed by one of us that during the heating of an oil containing asphalt, the asphalt apparently induces certain chemical and perhaps certain physical reactions `at relatively low temperatures which tend to destroy the inherent low viscosity temperature susceptibility of the lubricating oil fractions. This apparent catalytic phenomenon seems to explain the observed changes although we do not wish to be understood'as bein'gbound by this theory. It has been observed that these temperatures at which the changes appear are below the vaporizing temperatures in batch distillation (vacuum or steam) of the lubricating oil fractions which have Saybolt Universal viscosi- The oils of various. .viscosity are made by blending these neutrals" (Cl. 196--13) Y nes above 40u00 seconds "at 100 F. It is safe to say that no oil containing asphalt can be topped to the point where fractions above 400-500 seconds, Saybolt Universal viscosity vat 100 F.'

are vaporized without a degeneration of those characteristics of the pa`raiiln' `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 conguration 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.

In order to. preserve the inherent characteristics of the lubricating oil components of crude oilcontaining asphalt which are impaired by distillation methods as previously described, we have, inaccordance with the process of the above-application, caused the separation of the' oil andy wai 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 ai@ light petroleum fractions, such as naphtha, casinghead rgasoline 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 frac- ---tion obtained by the rectincation of natural gas- In Vthis liglit liquid fraction the solution 'is malntained at a pressure suiiicient to maintain the propane liquidV at ordinary temperatures. The

fraction described above isl liquidja't ordinary temperatures at`a pressure of about pounds per square inch.' The extraction of the oil from be obtained if the sulphur dioxide extractioni .operation were performed subsequent to wax re-g 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 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 thel oils which exhibit a low temperature viscosity susceptibility parafilnoidand those which exhibit a high temperature viscosity susceptibility 'and resemble the western lubricating oil distillates non-paraff noid. The propane extract which consists of such a mixture of parainoid and non-paramnoid oils may be separatedinto 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-paraiilnoid oils. As solvent 1agents 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 measurethe ability to split the oil in the above manner. The use of liquid sulphur dioxide has been found Vespecially valuable as a solvent to separate the pro pane 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 confsists of a mixture of wax and oil normally solid at ordinary temperatures, it cannot be separated into its paraftinoid and non-paramnoid components by the use of sulphur dioxide, without considerable difliculty, unless dissolved in a carrying medium. We have found it advantageous to carry out the extraction of thewax-oil mixture with sulphur dioxide 'in the presence oi the liquid propane used iny yseparating the asphalt. The wax oil mixture is dissolved in liquid prone dioxide to remove therefrom the non-paroid components. The propane solution of paraoid oil is then chilled to precipitate the wax present after which the chilled mass is cold settled,l centrifuged, or filtered to separate thegwax from the propane solution of oil. By removing the sulphur dioxide soluble bodies from the propane solution of waxy oil prior to the dewaxing opera` tion we are able to obtain a nal product with a lower pour point, i. e., wax content than could moval. The sulphur dioxide removes from oil certain bodies present which 'are good wax selvents and whichv have a tendency to prevent precipitation of the wax during the dewaxing operation.

The propane solution of oil recovered from the lfrom the paraiiin 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 paraliinoid from the non-paraiiinoid 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 and paraffinoid oil from the non-paraflinoid oil by means of a second solvent used in the presence of the first solvent, to separate the wax from the paramnoid oil and thereafter to treat the parainoid oil dissolved in said rst solvent with sulphuric acid. Y

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 separate the wax and paraiiinoid oil `from the non-paraflinoid oil by the use of liquid sulphur dioxide in the presence of liquid propane; to separate the wax from the paramnoid oil and thereafter to treat the paraffinoid oil with sulphuric acid. y

The drawing represents one form of apparatus which We may employ to carry out our process.

Referring more particularly to the drawing, the

,crude oil which has been distilled to remove light oils such as gasoline and kerosene and is itself a residual cil containing lubricating fractions, asphalt and Wax in tank i is withdrawn through valve 2 and sent by means of pump 3 through line i where it meets a stream of liquid propane coming from tank l0 through valve il, line i2, pump t EE and line I2. The mixture of topped crude and liquid propane passes from line l to chiller 5 where a portion of the propane is allowed to vaporize through valve 6 and passes by means of line 'i to pump 32 where it is compressed and sent to condenser t where it is liquefied and sent by means of line t tostorage tank Il). ,The vaporization of the propane in chiller 5A causes the temperature o the mass therein to be lowered. The cool mass from chiller Ei passes by means of line i3 to agitator ld where it is thoroughly mixed and sent by means ofline i5 to decanter i6 Where the asphalt is allowed to settle out. y y

'I'he asphalt isWithdrawn from decanter it through valve il and sent by means of pump it through line i 9 to heater 2l) where the propane and moisture are vaporized. The heated mass passes from heater 26 through line 2| to separator 22 where the asphalt separates from the vapors and is withdrawn through valve 23 and line 2t in the storage tank 25. The vvapors in separator 22 are withdrawn through line 26 into condenser 2li 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 tSthrough line 3l to compressor H3 thence to condenser 8 where it is liqueed and passes by means of line 9 to storage tank I0.

The solution of oil in liquid propane in decanter I6 is withdrawn through line 33 and sent to chiller 34. A portion of the propane present is allowed to vaporize by opening valve 35 and` allowing the vapors to `pass through line 36 to compressor ||6 where it is compressed and sent to condenser 8 and is liqueed, thereafter being sent to storage tank l0. The vaporization 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 4 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 ofthe 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 4| through the valve 46 and sent by means of line 41 to vaporizer |05 where the sulphur dioxide is vapor-- ized by aid of steam introduced through closed coil 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 is withdrawn through valve |02 and sent through line |03 to tank |04.

The ascending column of oil ,in extraction column 4|, from which the liquid sulphur dioxide soluble components have been removed, passes through valve 48 to line 49 to auxiliary separator 50 where any remaining liquid sulphur dioxide is. settled out. A clear solution of oil is withdrawn from auxiliary separator 50 through line 52 where it may be mixed with a further quantity of liquid propane coming from storage tank I0 through valve 53, pump H4 and line 54. The solution of oil 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 III Where it is compressed and sent through line 88 to condenser 89 where both the sulphur dioxide and the propane are condensed and pass by means of line to separator 90 where these two materials separate due to their great difference 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 inchiller 55 cools the remaning solution of oil present which passes out through valve 56 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 lter 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 ofacd and oil passes from line 61 through agitator 68 where the mass is thoroughly agitated, after which it passes through line 69 to separator 10 where theV sludge is allowed to settle out. The sludge in separator 10 is withdrawn through valve 15, line 16, to pump 11 which forces it through line '18 to heater 19 where the mass is heated sufiiciently to vaporize the propane present. The heated mass passes from heater 19 through line 80 to separator 8| 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 withdrawn from separator 8| through line 85 to compressor H2 where it is compressed and sent by means of line 88 to condenser 89 where it isliqueed and sent by means of line ||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 sludge is separated out. The fraction'of oil leaving clay tower 12 passes by means of line 13 to evaporator 14 Where the propane and sulphur dioxide present are vaporized by 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 separatorv 90. Liquid propane in separator 90 is returned to storage tank |0 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 1 4 which is free from propane and sulphur dioxide is removed through valve 98 and sent by means of line 99 to rei-ined 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 of Fig. l 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 undissolved asphalt. This oil dissolved in liquid propane contains a mixture of parainoid and non-parafnoid 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 nonparafnoid nature soluble in liquid sulphur dioxide and a portion of a paraflinoid 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 paraffinoid oil and wax dissolved in liquid propane is then chilled to a point sufcient to cause precipitation of the Wax, after which the chilled mass is ltered, centrifuged or cold settled to remove the wax. The Wax-free solution of parainoid 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 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 process for the production of lubricating oil from oil which comprisesdissolving said oil in a liquefied normally gaseous hydrocarbon diluent, extracting said oil dissolved in said diluent with a selective solvent for non-parainoid fractions to form a fraction dissolved in said solvent and a fraction dissolved in said diluent, separating said fractions and treating said fraction dissolved in said diluent with sulphuric acid.

2. A process as claimed in claim 1 in which the hydrocarbon diluent contains a major portion oi propane.

3. A process as claimed in claim 1 in which the hydrocarbon diluent contains a major portion of hydrocarbons of less than four carbon atoms.

4. A. process as claimed in claim 1 in which the hydrocarbon diluent contains a major portion of hydrocarbons having less than three carbon atoms. 4

5. A process as claimed in claim 1 in which the selective solvent is liquid sulphur dioxide.

6. A process as claimed in claim 1 in which the acid treated oil is treated with clay.

7. A process for the treatment of lubricating oil from oil which comprises dissolving said oil in a liquefied normally gaseous hydrocarbon diluent containing a major portion of propane, extracting said diluted oil with liquid sulphur dioxide to form a fraction dissolved in said diluent and a fraction dissolved in said solvent, separating said fractions and treating said fraction dissolved in said diluent with sulphuric acid.

8. A process as claimed in claim 7 in which th acid treated oil is treated with clay.

ULRIC B. BRAY. CLAUDE E. S *Y 1li 'g

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