US1930479A - Dewaxing of oil - Google Patents

Dewaxing of oil Download PDF

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US1930479A
US1930479A US242028A US24202827A US1930479A US 1930479 A US1930479 A US 1930479A US 242028 A US242028 A US 242028A US 24202827 A US24202827 A US 24202827A US 1930479 A US1930479 A US 1930479A
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wax
oil
solvent
solution
mixture
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US242028A
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Leo D Jones
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SHARPLES SPECIALTY CO
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SHARPLES SPECIALTY CO
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    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G73/00Recovery or refining of mineral waxes, e.g. montan wax
    • C10G73/02Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils
    • C10G73/06Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils with the use of solvents
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S494/00Imperforate bowl: centrifugal separators
    • Y10S494/901Imperforate bowl: centrifugal separators involving mixture containing oil

Description

L. D. JQNES DEWAXING OF OIL @cfz. 17,
U U u 0 0000600006 Filed Dec.
Patented Oct. 17,1933
PATENT OFFICE DEWAXING or on.
Leo D. Jones, Philadelphia, Pa., assignor a The Sharples Specialty' Company,
Philadelphia,
Pa., a corporation of Delaware Application December 23, 1927 Serial No. 242,028
11 Clims.
This invention relates to a process for the removal of wax from petroleum products, the term fpetroleum products being used herein to designate the substances that may be dewaxed in accordance with this invention andincluding crude petroleum oils from various sources, and mixtures thereof, and distillates or residues or other fractions or intermediate or final'products occurring in or resulting fom the refining of crude petroleums, and mixtures thereof.
One aspect of this invention is that it is an improved centrifugal process for the dewaxing of petroleum products, but important features of the. invention are not limited to that point of view and are of general application in the dewaxing of petroleum products by other processes.
The known practice in the removal of wax from petroleum products is as a whole subject to numerous limitations and'to many dimculties. In
known practice wax has been removed from petroleum products by filter pressing and by cold settling and more recently, but on a large scale and more completely and more rapidly, by centrifugal separation. In each of these methods the wax is precipitated, preperatory' to its removal, by chilling 'the product or mixture from which the wax is to be removed, the mixture be- I ing especially fluid prior to chilling because of v either added naphtha or light petroleum products formed in the preparation,as by cracking distillation, of the product to be dewaxed; and it has been proposed to add to the'oil-naphtha solution foreign particles to which wax may adhere. but in that operation one of, several difliculties is the removal of theparticles from whatever wax adheres to them. Butv each of these .methods of removing wax from petroleumjs subject to numerous limitations and to various de-o gres of difliculty. If a wax-containing petroleum product is merely chilled, with or without dilution, to precipitate the wax, filter pressing can only be employed to remove the preciptated wax when it is distinctly crystalline in nature, as in the case of cracked distillates.
is subjected to further cracked distillation or maybediluted with naphtha. Cold settling can only be employed when the wax precipitated by chilling is distinctly amorphous in nature, as in the case Crystalline wax-containing fractions of crudepetroleum are settle. Ordinary centrifugal dewaxing of petro-' leum products, consisting of diluting with naphtha and chilling and centrifugally removing, with the use of a carrier liquid, the precipitated wax, has been highly successful in removal of wax that is distinctly amorphous when precipitated and is capable of dewaxing certain distillates and the long residuum (the residue after removal of gas, naphtha and burning oil) of some crude oils. Other petroleum products can be dewaxed successfully by centrifugal methods which involve special steps whereby the particular characteristics of the wax are taken into account. When some. petroleum products are merely mixed with naphtha and chilled the precipitated wax is neither sufliciently crystalline to be rev such wax is heavier than that solution and large! lyjamorphous and such petroleum products can not be dewaxed by processes depending upon' differences between the'specific gravity of the oil and the wax, orby filtering.- It has been' common practice to subject such petroleum products to cracking distillation to bring the wax content into crystalline form but that step has resulted in considerable losses due-to conversion of large fractions of the oil into nonlubricating oils. Such petroleum products may be dewaxed centrifugally when naphtha is employed as a solvent provided special processes are used and carried out with considerable care. lf'naphtha, of especially low specific gravity is used in order to reduce the specific gravity of the oil-naphtha'solution after chilling, for the purpose ofcausing the oil-naphtha solution to be lighter than all of the precipitated wax'or for the purpose of increasing the difference between the specific gravities of the wax ands lution, large evaporation losses occur, partic rly in the' heating of the mixture preparatory to the chilling. If, theproportion' of naphtha, used as a solvent, that is added to the wax-containoil product.
ing product prior to chilling is increased for the purpose of reducing the specific gravity of the oil-naphtha solution to a value below that of light constituents of the wax precipitated by chilling, the cold test of the final oil is impaired because there is less oil in the resulting oilnaphtha solution and the wax that remains in solution in the oil-naphtha solution after chilling remains in solution in that reduced quantity of oil after naphtha is distilled therefrom and produces an unusually high wax content in the final In commercial operation filter pressing produces oil having a cold test of 25 F. to 30- F. and cold settling produces oil having a cold test of about 50 F., and ordinary centrifugal dewaxing produces oil with a cold test of 15 F. to 25 F. Other limitations and-defects in the known practice of dewaxing petroleum are well known to those skilled in the art and some of such defects and limitations will be referred to hereinafter.
It is an object of this invention to provide a process for the dewaxing of petroleum products in which the defects and limitations of prior practice are eliminated or minimized. Other and further objects and advantages of my invention will appear from the following description or will be apparent, in the light of such description, to those skilled in the art.
In accordance with my invention, wax-containing petroleum products are diluted with an oil solvent that is of such character and is present in such proportion that all of the wax precipitated by chilling, of the mixture is lighter than the residual solvent-oil solution, and then the wax is precipitated by chilling and separated from the solvent-oil solution. The dewaxed oil is recovered from the solvent-oil solution in any suitable manner, as by distillation, and the wax is freed of solvent in any suitable manner. Thus, in the practice of my invention the precipitated wax rises to the surface of the chilled mixture under the action of gravity or accumulates in the inner zone of the centrifugal bowl. Inprior practice an effort to have the solvent-oil solution lighter than wax precipitated therein limited the solvents used in commercial practice to light petroleum products. With such light solvents some of the wax in the product to be dewaxed might be lighter than the solvent-oil solution and the remainder of the wax heavier. In such case the use of a lighter solvent caused evaporationlosses, and use of a greater proportion of solvent carried an undesirably large quantity of wax in the oil finally produced. In some of such cases neither the use of lighter solvent nor the use of a greater proportion of solvent would cause the solvent-oil solution to be lighter than all of' the wax and the wax could not be removed from such a mixture by gravity or by centrifuging, and usually, in such a case, the precipitated wax could not be separated by filter pressing because it would be too amorphous as a whole. Thusjin former practice there were limitations upon'the relative lightness of the solvent and those limitations imposed further limitations upon the kinds of wax that could be separated by particular operations. But, in accordance with my invention a solvent is selected that willcause all of the precipitated wax, regardless of its character, to be lighter than the solvent-oil solution." Thus, solvents may be so selected that the difference between the specific gravities of the wax and of the oil-solvent solution are relatively great as compared with the difference between the specific gravities of the wax and of the oil-naphtha solution. This difference of specific gravities is always necessarily small when naphtha is employed as a solventand sometimes the specific gravity of the oil-naphtha solution is intermediate of the specific gravities of different constituents of the wax present. Again solvents used in the practice of my invention may be less volatile than the naphtha ordinarily employed and much less volatile .than the light naphthas employed in the dewaxing of oils containing some relatively light wax. The difference be tween the specific gravities of the wax and of the oil-solvent solution being obtained by selection of the solvent, it is not necessary in the practice of my invention to use excessive quantities of solvent or to use very light solvent that is undesirably volatile or to adopt both of those expedients in order to obtain the necessary difference of specific gravities, and the objectionable results of those expedients are avoided.
Examples of solvents that may be used in the practice of my invention are gas-oil, benzene, dichlor ethane, carbon tetrachloride, dichlor propane, carbon disulphide, chlor benzene, etc. A distinct advantage of using such solvents is that a solvent may be selected that contains less wax in solution after precipitation of the wax by chilling than is contained in light petroleum products formerly employed. Thus, in the practice of my invention a solvent may be used that has a greater diiferential solubility as between wax and oil, especially at temperatures employed in commercial dewaxing, than solvents of the limited field heretofore employed. Furthermore, with the use of such solvents, in the practice of my invention, the chilling for the precipitation of wax does not always have to be carried to 'as low a temperature as mixtures of 'oil and naphtha, to produce oils of even lower. cold test than oils produced by using light petroleum products as solvents and chilling to much lower temperatures. Moreover, while the solvents heretofore used have been limited to light petroleum products having a specific gravity up to 55 Baum, solvents employed in the practice of my invention are not limited topetroleum products and therefore solvents may be employed that have characteristics differing greatly from light petroleum products, and a solvent may be selected that has characteristics best, suitedfor the separa tion of wax from the particular oil that is being handled. Also, in the practice of my invention it becomes possible to use solvents consisting of mixtures of substances, each of. which possesses some property that contributes toward the efliciency or economy of the dewaxing operation. When light petroleum products have been used as solvents it has been-necessary to exercise care in chilling the mixture in order to avoid any sudden lowering of the temperature thereof, but in using solvents contemplated in my invention, and particularly ethyl- "ene dichloride, good results have been obtained with various rates of chilling and the precipitation is not as sensitive to variations in chilling asin the case when naphtha is employed. 4 In all dewaxing processes involving the addition or presence ofa solvent it is important that the chilled solution be sufficiently fiuid to facilitate'the removal of wax therefrom. But it is desirable and is entirely possible in the practice of my invention to avoid using a proportion of solvent in excess of thisrequirement. Increasing the proportion of solvent beyond that which is necessary to meet this requirement increases the amount of wax that phous for one operation or too crystalline for the other or because the naphtha-oil solution can-. not practicably be made lighter than all of the precipitatedwax, losses occuring in the early practice of subjecting the oil to cracking distillation to bring the wax to -a crystalline condition have largely been avoided by later practice. In such later practice the wax in such oils is brought as a whole to a condition in which it is all heavier than an oil-naphtha solution after chilling and in which it can readily be discharged from the centrifuge, this condition being achieved by adding amorphous wax or oil containing amorphous wax or by adding or otherwise adjusting or regulating the content of color-forming impurities that occur in petroleum oil, or in resorting to'two or more of such expedients, centrifugal separation employing acarrier liquid being preferably for the removal of such wax from such a mixture. But, in accordance with my invention petroleum prodf ucts containing wax of such characteristics maybe dewaxed without cracking and without using such special steps, because the precipitated wax can be caused to be lighter than the oil-solvent solution by selecting a suitable solvent that is not undesirably volatile and need only be used in economical proportions. By the practiceof my invention it is readily possible to obtain petroleum oils and particularly lubricating oils having 'a cold test of zero degrees pressing, cold settling or centrifugal separationis employed.
My invention is generally applicable to the dewaxing of. petroleum products, and, while it is not limited to the centrifugal removal of wax from-the chilled mixture, it is particularly adapted to that type of wax removal. In centrifugal dewaxing the above described advantages and many other advantages of my invention are obtainedf' p In the centrifugal separation of precipitated wax from a chilled solution of oil, when naphtha has been used as the solvent, the wax constitutes the heavier constituent and several difficulties arise that are avoided in the practice of my invention. The centrifugal bowl contains a dividing wall through the center of which the lighter constituent of a mixture is directly discharged through a relatively simple passage. The dividing wall extends radially outward to a point near the inner surface of the bowl, and when wax is the heavier constituent in the mixture a carrier liquid is employed that fills the outer zone of the bowl and engages the outer edge of the dividingwall and forms a liquid surface facilitat-- ing the movement of wax that might adhere to the inner surface of the bowl; and a body ofcarrier liquid occupies the space between the dicharged.
viding Wall and the end of the bowl and maintains hydraulic balance with the wax and oil in the main body of the bowl. Thus, when wax is the heavier constituent it must pass around the outer edge of the dividing ,wall and up through the carrier liquid in the auxiliary compartment and then -pass through relatively complicated dischargepassages. When naphtha is used as a solvent it is necessary that the naphtha-oil solution shall all be lighter than the precipitated wax and necessary that the wax be capable of passing around the edge of the dividin wall and through the discharge passages, even though the presence of crystalline wax and hard asphalt impose difiiculties upon the discharge of wax from the centrifugal bowl. To avoid these difiiculties it has been necessary at times to use excessively light solvent or excessive quantities of solvent necessary to remove hard asphalt by mild acid treatment preliminary to centrifugal dewaxing.
The complicationscin the discharge passage for the heavier substance from the centrifuge make it difficult to apply heat in such a way as to assist the discharge of crystalline wax or hard wax, or hard asphalt, without heating the contents of the bowl and thereby impairing the wax separation.
' In the practice of my invention the wax is lighter thanthe solvent-oil solution and there- .fore passes to the central zone of the centrifuge and is discharged directly through thg relatively simple discharge passage leading therefrom while I the wholly-liquid solvent-oil solution passes to the outer zone and flows through the more or less complicated discharge construction. The discharge of wax from the central zone of the centrifug'e' imposes fewer difficulties upon the discharge of hardand crystalline wax and asphalt and affords greater opportunity for the application of any necessary heat toa substance so dis The use of carrier the .practice of my invention in which the wax discharges from the central zone of the bowl.
It will now be apparent that the difiiculties of centrifugal dewaxing due to the presence of crystalline wax or-asphalt, or due to relativelightness of some part of the wax or variations in the specific gravity of different constituents of the liquid is not necessary in wax, areavoided by my invention and that the use of carrier liquid is dispensed with and that it becomes relatively simple to apply heat or other treatment to facilitate the discharge or to change the character of the wax. And, it will be apparent that in the practice of my invention all petroleum products including distillates and residues and mixtures may be dewaxed by added to the wax-containing product and it is.
chilled to precipitate the wax and introduced through pipe 6 to the centrifugal bowl 1. The bowl contains a member '1 having three radial wings and held in position by resilient members 8 and acting to cause liquid to assume the speed of the bowl. Under the influence of centrifugal force the oil-solvent solution will 'be segregated at the outer zone of the bowl and passed around the outer edge of the dividing wall 9 thereof and will be discharged through passages 10 (only one of which is shown). The waxwill be segregated in the inner zone of the bowl and will pass over the weir ll of the dividing wall 9 and will be discharged from passages 12 (only one of which is shown). The level of the oil-solvent solution is determined by the inner diameter of the ringlike weir 13 which is replaceably held in position by the nut 14 and the radial depth of oil-solvent solution between the inner edge of the weir 13 and the outer edge of the dividing wall 9 will be so adjusted by selection of a weir 13 of proper internal diameter, that that depth of oil-solvent solution will maintain hydraulic balance with the wax and oil-solvent solution in the main compartment of the bowl. Oil-solvent solution will be collected in the receiving cover 15 and discharged therefrom through spout 16 and wax will be collected in receiving cover 1'7 and discharged therefrom through a spout 18. To facilitate discharge of unusually firm or adhesive wax from cover 1'7, there may be provided an annular chamber 19 receiving hot fiuid through pipe 20 and jetting it 'through orifices 21, liquid so discharged against the neck of the bowl being dispersed in cover 1'7 and thrown against the walls thereof to facilitate the fiow of wax from the cover. Spout 16 is preferably provided with a trap 22 while wax from spout 18 is collected in a receiver 23.
From the foregoing it will be apparent that in accordance with my invention wax-containing petroleum products may be dewaxed centrifugal ly with only the simple operations of diluting and chilling as preparatory steps and that such products may be so dewaxed regardless of the nature of the wax-regardless of whether it is crystalline, amorphous, or mixedand regardless of the manner in which the particular petroleum product was produced.
Examples of the separation of wax from oil that further illustrate my invention are as follows:
A lubricating distillate of Mid-Continent crude oil-a fraction that is termed slop distillate in commercial practice-was diluted with naphtha and chilled and subjected to centrifugal treatment all in accordance with the best known previous practice but without successful results, because some of the wax was lighter than the oil-naphtha solution and, perhaps because of the presence of crystalline wax, discharge of wax from the bowl ceased. Then petrolatum from Mid- Continent crude oil was added in such proportion as to bring the wax content of the distillate to such specific gravity and consistency as to permit centrifugal separation of the wax, and with the mixture properly chilled centrifugal separation produced oil having a cold test of 25 F. Then a mixture was made of which 30%, by volume, consisted of another quantity of the same lubricating distillate and 70%, by volume, consisted of ethylene dichloride, and this mixture was rapidly a cold test.
Again, light distillate of Mid-Continent crude oil-the fraction between 100 seconds and 250 seconds Saybolt Universal viscosity at 100 F. was similarly treated. When this distillate was merely diluted with naphtha and chilled and cen-' trifugally treated, all in accordance with the best known previous practice, the centrifugal separation was not successful. When a proper quantity of petrolatum was added to the oil and it was diluted with naphtha and chilled and centrifugally dewaxed, the final oil product had a cold test of 25 F. A final oil having 0 F. of cold test was obtained when ethylene dichloride was used as a solvent in the proportions used in the first example and the chilled mixture was centrifugally dewaxed, and the wax obtained was so crystalline that it sweated itself out to a hard paraffin. It has heretofore been impossible to remove such wax from oil by merely diluting and chilling and then removing wax by a process dependent upon differences in specific gravity between the wax and the solution.
Again, heavy pipestill distillate of Mid-Continent crude oilpractically a cylinder stock-. was mixed, afterlight acid treatment, that removed hard asphalt, with ethylene dichloride in the volumetric proportion of 35 to 65 and the mixture was chilled to about 15 F. and centrifugally dewaxed. The oil produced, freed of emylene dichloride, had a cold test of 10 F. and did not cloud at 0 F. The wax obtained had a melting point of 124 F. V
In the practice of my invention the wax-containing oil is mixed with a solvent of such nature that the wax will be lighter than the remaining solution after the mixture has been sufficiently chilled to effect precipitation of the wax. Sufficient solvent is used to insure that the mixture will be suificiently liquid after chilling to permit proper removal of wax. When light petroleum products have been used as the solvent, the mixture has heretofore been chilled to 10 F. or only slightly lower for the purpose of precipitating the wax, and even more extensive chilling has been desirable but has been prevented by economical considerations. However, in the practice of my invention, the chilling need only be carried to a point at which suitable precipitation occurs and I have found that when ethylene dichloride is employed as a solvent, a lower cold test oil is obtained by centrifugal separation from a mixture that has been chilled to 15 F. than could be obtained if a' wax-containing oil had been chilled to 10 F. in connection withthe use of naphtha as a solvent.
It will be apparent from the foregoing that in accordance with my invention wax-containing petroleum products may be dewaxed to a degree higher than that previously attained in commercial practice and by simple steps, and that the procedure is effective independent of the character'of the wax that is'to be removed. It is to be noted, however, that important advantages of my invention that are obtained without regard to the manner in which the wax is actually removed fromthe chilled mixture.
The use and advantages of solvents heavier than wax in the separation of wax from oil, particularly by processes depending upon differences of specific gravity between wax and oil-solvent mixtures, constitute the subject matter of thistate formed by chilling the solution of wax-containing oil is not, strictly speaking, ere'wax but comprises wax, oil and solvent; and theresidual liquid in which the precipitate is formed comprises both oil and solvent and sometimes contains some residual wax-that is not precipitated. Accordingly, it is to be understood that the reference herein to precipitated. wax is intended as a reference to a precipitate of the character above mentioned; and references herein to oil are intended to include both oil and solutions of oil, which may also containlwax.
I claim:
1. In the production of dewaxed lubricating and distillates obtained from wax-containing mineral oil, the steps comprising mixing a waxcontaining lubricating-oil fraction with dichlor ethane, cooling the mixture to a temperature at which wax precipitates/land oil and the solvent remain liquid, separating precipitated wax from the cooled mixture by centrifugal. subsidence, and separately discharging continuously from the centrifuging operation wax and clear solution of dewaxed oil.
2. In the production of dewaxed lubricating oil from wax-containing lubricating-oil residues and distillates obtained from wax-containing mineral oil, the steps comprising mixing a waxcontaining lubricating-oil fraction containing amorphous wax wth dichlor ethane, cooling the mixture to a temperature at which wax including amorphous wax precipitates and oil and the solvent remain liquid, separating precipitated wax from the cooled mixture by centrifugal subsidence, and separately discharging continuously from the centrifuging operation wax and clear solution of dewaxed oil.
3. In the production of dewaxed lubricating oil from wax-containing lubricating-oil residues and distillates obtained from wax-containing mineral oil, the steps comprising mixing a waxcontaining lubricating-oil fraction \1 containing crystalline wax with dichlor'ethane, cooling the mixture to a temperature at which wax including crystalline wax precipitates and oil and the solvent remain liquid, separating precipitated wax from the cooled mixture by centrifugal subsidence. and separately discharging continuously from the centrifuging operation wax and clear solution of dewaxed oil. 3
4. In the production of dewaxed lubricating oil from wax-containing fractions of mineral oil, the steps comprising mixing the wax distillate of crude wax-containing petroleum with an oil solvent containing sufiicient dichlor ethane to cause the resulting solvent-oil solution to possess a specific gravity higher than that of wax precipitated in the mixture by cooling thereof,
cooling the mixture to a temperature at which wax precipitates therein and oil and the solvent remain liquid, separating precipitated wax from the cooled mixture by'centrifugal subsidence, and separately discharging continuously from the centrifuging operation wax and clear solution and distillates obtained from the wax-containing mineral oil, the steps comprising forming a mixture of the wax-containing oil and an oil-.
solvent containing suflicient dichlor ethane to causethe resulting solvent-oil solution to possess a specific gravity higher than that of wax precipitated from the mixture by cooling, cooling the mixture to a'temperature not substantially below that at which the wax is precipitated to a desired degree, separating precipitated wax from the cooled mixture by centrifugal subsiilence, and separately discharging continuously from the centrifuging operation wax and clear solution of dewaxed oil. 1
6. In the production of dewaxed lubricating oil from wax-containing lubricating-oil residues and distillates obtained from wax-containing mineral oil,'the steps comprising forming a mix-- ture of the wax containing oil and an oil-solvent containingsufiicient dichlor ethane to cause the I L resulting solvent-oil solution to possess a specific oil from wax-containing lubricating-oil residues gravity higher than that of wax precipitated from the mixture by cooling, cooling the mixture to a temperature not substantially below that at which the wax is'precipitated to a desired degree, 7 and separating precipitated wax from the cooled mixture to produce clear solvent-oil solution.
7. In the production of dewaxed lubricating oil from wax-containing lubricating-oil residues and distillates obtained from the wax-containing mineral oil, the steps comprising adding to the wax-containing oil a solvent which comprises dichlor ethane and a petroleum fraction lighter than the oil to be dewaxed, said solvent having such specific gravity and being added in such proportion that the resulting solvent-oil solution will posses a specific gravity greater than that of wax precipitated in the mixture by cooling, cooling the mixture to a temperature at which wax precipitates and the oil and solvent remain liquid, andseparating precipitated wa'x from the mixture and thereby producing clear solventoil solution.
8. In the production of dewaxed lubricating oil from wax-containing lubricating-oil residues and distillates obtained from wax-containingmineral oil, the steps comprising adding to the wax-containing oil a solvent mixture comprising dichlor ethane and a hydrocarbon that remains liquid at all temperatures encountered in the wax-separating operation, the solvent mixture being added in such proportion that the resulting solvent-oil solution has a specific gravity greater than that-of wax precipitated by cooling of the mixture, and separating wax from the cooled mixture and thereby producing clear solution of dewaxed oil. I
9. A method for producing dewaxed residual lubricating oil having a pour test of substantially 0 F. from wax-containing petroleum which com-= prises mixing a residue of wax-containing petroleum with a solvent comprising a dichlor ethane, the solvent having such specific gravity and being present in such proportion that the specific gravity of the solvent-oil solution is greater than that of wax precipitated in the mixture by cooling, cooling the mixture to a temperature at which wax is precipitated ,to a desired degree while the oil to be dewaxed remains in solution in the solvent, separating the precipitated wax from the cooled mixture, and separating the solvent from the dewaxed solvent-oil solution and thereby producing dewaxed, natural, re-
sidual lubricating oil having a pour test of 0 F. to 10 F.
10. A method for producing natural, dewaxed, lubricating oil having a pour test of substantially 0 F. from distillates and residues of wax-containing petroleum; which comprises mixing a substantially uncracked fraction of 'zwax-contain-f ,ing'petroleum with an oil-solvent comprising,
dichlor ethane, said solvent having such specific gravity and being present in such proportion that the resulting solvent-oil solution has a specific gravity greater than that of wax precipitated in the mixture by cooling, cooling the mixture to a temperature at which wax is precipitated to a desired degree while'the oil to be dewaxed and the solvent remain liquid, separating precipitated wax from the cooled mixture, separating the solvent from the dewaxed solventoil solution and thereby producing natural, dewaxed lubricating oil having a pour. test between 11. 'In the production of dewaxed lubricating oil from wax-containing lubricating-oil residues 0F. and 10 F. from wax containing petroleum and distillates obtained from the wax-containing mineral oil, the steps comprising forming a mixture of the wax-containing oil and sufiicient of an oil solventof the group consisting of dichlor
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2538870A (en) * 1947-09-08 1951-01-23 Atlantie Refining Company Dewaxing hydrocarbon oil with vortex separator
US2952609A (en) * 1957-07-24 1960-09-13 Sun Oil Co Centrifugal dewaxing process
US2985642A (en) * 1956-10-26 1961-05-23 Gillespie Rogers Pyatt Co Inc Art of dewaxing shellac
US3010702A (en) * 1955-02-16 1961-11-28 Separator Ab Heat exchange for continuous throughflow of two media
USRE30836E (en) * 1972-11-10 1981-12-29 Kobe, Inc. Liquid-gas separator unit

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2538870A (en) * 1947-09-08 1951-01-23 Atlantie Refining Company Dewaxing hydrocarbon oil with vortex separator
US3010702A (en) * 1955-02-16 1961-11-28 Separator Ab Heat exchange for continuous throughflow of two media
US2985642A (en) * 1956-10-26 1961-05-23 Gillespie Rogers Pyatt Co Inc Art of dewaxing shellac
US2952609A (en) * 1957-07-24 1960-09-13 Sun Oil Co Centrifugal dewaxing process
USRE30836E (en) * 1972-11-10 1981-12-29 Kobe, Inc. Liquid-gas separator unit

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