US2221161A - Treatment of naphthene base oil - Google Patents

Description

Nov. 12, 1940. c. T. ANN ETAL TREATMENT OF NAPHTHENE BASE OIL Filed Aug. 25; 1958 N Y .www im n Mmm L@ 3mm 02m mmmwf, n Hmmlu/ A CHL R w M/Um B T +I UNITED STATES oFFicE TREATMENT OF NAPHTHENE BASE OL Charles T. Ann, Herman I. Wilson, and William C. Patterson, Port Arthur, Tex., assignors to The Texas Company, New York, N. Yi, a corporation of Delaware Application August 25, 1938, lSerial No. 226,630

11 claims. (o1. 19e- 34) This invention relates to the treatment of the undesired asphaltic and tarry bodies, all, or naphthene base oil. It particularly concerns the substantially all, of thoseconstituents present in treatment of lubricating oil stocks derived from the oil and Awhich impart to the oil a desirable naphthene base crude petroleum for the producgreen cast. Vacuum distillation over caustic also tion of lubricating oils substantially free from destroys this green cast. Thepurpose of distilling asphaltic and organic acidic constituents but havover caustic is to remove the naphthenic acids in ingia desirable green cast or bloom. the form of a soap which remains .behind in the The invention broadly contemplates treatment still as a residue. The desirable'green colorof fractions derived from naphthene base crude forming vconstituents apparently remain in this by a process involving deasphalting in the' presresidue and consequently are not' present inthe 10 ence of a liqueed normally gaseous petroleum distillate lubricating oil fractions. Y hydrocarbon solvent and treatment of these frac- From a praCtiCai StaldDOint it iS imPOSSible t0 tions with alkali in the presenceof the liquefied effect removal of the naphthenic acids from the solvent for the purpose of separating therefrom oil by simply Washing with caustic soda solution,

15 the naturally occurring organic acid-constitudue to the extreme readiness with which emul- 15 ents. o o sions are formed and the extreme difficulty en- The process of this invention is particularly countered in breaking .these emulsions. Distillaadapted to the preparation of lubricating oilhavtion of the oil over caustic, does not give rise to ing a desirable green cast and substantially free emulsion diiculties butfor some reason or from asphaltic and acidic constituents from lubriother, as indicated above, the resulting distillates 20 eating oil stocks derived from naphthene base khave a bluish cast instead of the desired green crudes and. particularly the residual fractions of cast. such crudes. y It has been discovered that naphthenic acids l The process is also applicable,4 to the treatment can bek removedv from this oil by treatment With of heavy residual fractions of naphthene baseV alkali in the presence Of a dilnenty SllCh aS PI'O- 25 crudes rich in naphthenic acids such as the still pane, WthOut encountering particular difficulty 1 bottoms produced in the vacuum distillation over with respect t0 the formatiOn OfemlliSiOnS- BY caustic of lubricating oil fractions derived from carrying Out the treatment Under Certain speci- Gulf Coastal crude. These bottoms are treated ed conditions, as will be explained mere'fully, with acid in order to liberate a fraction comprisit is possible to substantially avoid the formation 30 ing crude naphthenic acids. This crude fraction 0f emulsions which are diliicult to break.I Prois treated with propane to precipitate asphaltic pane deasphalting, Geupled With treatment with and tarry matter. Following this, the naphthenic the alkali, pIOdllCeS a DI'OduCt 0f Superior ChaI- acid material, while still diluted with propane, is acteristics and also `avoids the necessity for subtreated with an alkali to saponify the acids and jecting the resulting oil stock to treatment with 35 `theresulting saponied material is then separated sulphuric or other inorganic acids as practiced from the oily constitutents. The saponied acids in the prior art. may be subsequently treated with an inorganic It is advantageous to employ lthe alkaline acid in order to liberate them. treatment of this invention invconjunction with It has been found that lubricating oils of dedeasphalting 0f the Oil With a S01Vent Such as 40 sirable green cast can be prepared by deasphaltpropane, because the propane used in the deing naphthene base reduced crude and treating asphalt-,ing step serves as a diluent in the alkali the oil, while in propane solution, with an aquetreating Step. thus acting as a common diluent in ous solution of caustic soda for the removal of both steps. It is-possible that the propane facilinaphthenic acids. tates the retention of the desirable color-forming 45 In the conventional treatment of this type of constituents in the oil during the treatment with reduced crude this green cast is destroyedand alkali, thus preventing their removal in thesaoil having a blue cast or bloom results. l ponied material, as is the oase when distilling The conventional treatment of these lubrithe oil over caustic, as explained above. 5o eating oil fractions has usually involved treatment In order ,to illustrate the invention further, 50 with an inorganic acid, followed by neutralizareference will now be made to the accompanying tion. Vacuum distillation over caustic has also drawing:A been employed, or a combination such as chem- A residual naphthene base lubricating oilstock, ical treatment and vacuum distillation. obtained by distilling the lighter fractions from Acid treatment apparently removes, along with. a Gulf Coastal crude, is conducted from a source 55 not indicated to a mixer I. Propane, conducted from a source not indicated, is introduced to the mixer I wherein it is mixed with the lubricating oil stock in the proportion of about 8 to 12 parts of propane to 1 part by volume of stock. The resulting mixture is conducted to a separator 2 wherein it is subjected to settling at a temperature around 70 F. to 180 F in order to precipitate asphaltic constituents. The thus deasphalted solution is advantageously conducted to a second separator 3 for the precipitation of further asphaltic constituents of a resinous nature and which is effected by maintaining the mixture at a somewhat higher temperature, for example,

around F. to 200 F. If desired, an additional quantity of propane may be mixed with the l charge to the separator 3.

The completely deasphalted solution is now drawn off from the separator 3 and introduced to the lower portion of a treating tower 4. This tower may beprovided with suitable packing material. Advantageously, the packing may consist of several perforated cones 5 located in the lower portion of the tower. These cones are for the purpose of effecting contact and mixing between the .entering propane-oil mixture and the alkali.

Above the cones, and extending into the upper portion of the tower, grids 6 may be provided, advantageously consisting of wire screening.

Alkali, consisting of caustic soda dissolved in water, is introduced to the upper portion of the tower as indicated. In starting up the tower it is advantageous to flll it first with the mixture of propane and oil and then commence charging the caustic soda solution, allowing the level of the caustic solution to build up slowly to a desired level a short distance above the cones 5 and corresponding to the point indicated by liquid level indicator lI. The liquid level is maintained at this point during the continuous operation of the tower by drawing oif the spent caustic continuously from the bottom of the tower as indicated. In other words the interface level between the caustic layer and the oil layer is maintained relatively low in the tower. Sufficient pressure must be maintained on the system so as to maintain the diluent in a liqueed condition during the caustic treatment as Well as during the preceding deasphalting treatment.

The treated oil solution is continuously withdrawn from the top of the tower through a pipe 8. Through the pipe 8 the treated solution is conducted to a settling tank '9 where any aqueous carry over may be separated from the oil and drawn off. The settled mixture is then conducted to a stripper I0 wherein the propane is stripped from the oil.

Where it is desired to recover the naphthenic acids from the mixture being drawn olf from the botton ofthe tower d, this can be accomplished in the usual fashion by treatment with an inorganic acid so as to liberate the naphthenic acids.

The mixture of spent caustic drawn off from the bottom of the tower 4 may, if desired, be introduced to a washing tower II, provided with suitable packing material, and wherein it is washed with an additional quantity of the liquefied hydrocarbon solvent. The spent caustic solution is introduced to the upper portion of the tower, while a solvent, such as propane, is introduced to the lower portion of the tower. The washing is thus effected on the countercurrent principle for the purpose of removing from the spent caustic oil which may be associated therewith.

The washed caustic material is drawn off from the bottom of the tower I I while the solution of oil and propane is removed from the top of the tower and advantageously conducted to a washing tower I2, somewhat similar to tower II, but in which the washing agent comprises water. The Water and sludge is withdrawn from the bottom of the tower I2, while the washed solution of oil and propane is removed from the top of the tower and conducted to a stripper still to separate the solvent from the oil.

It is advantageous to employ a weak caustic soda solution in the tower 4 so as to prevent salting out of the naphthenic acid soaps during treatment within the counter-current tower. The caustic soda solution employed advantageously consists of around 0.2% to 0.5% by weight of caustic soda. It its advantageous to use it in substantial excess-that is, from 25% to 200% by volume in excess of the amount required to neutralize the organic acidity contained in the oil undergoing treatment. While more concentrated caustic solutions may be used as shown in the subsequent example, it is usually preferable to employ it in the less concentrated form.

While caustic soda has been specifically mentioned, it is contemplated that other alkaline reagents may be employed, such as ammonium hydroxide or potassium hydroxide.

While in the foregoing description the alkali treatment follows the deasphalting step, it is contemplated that instead it may precede deasphalting. If desired, the diluted oil may be subjected to alkali treatment subsequent to the initial deasphalting step and prior to the final deasphalting step for removal of resinous constituents.

The following results were obtained in treating a residual lubricating oil fraction having a viscosity of 270 Saybolt Universal seconds at 210 F. and derived from Manvel crude. Two runs were made. In the first run the resi'duum was subjected to deasphalting without a subsequent caustic treatment,v while in the second run it was subjected to both deasphalting and caustic treatment. The residuum was diluted with propane in the proportion of ten parts of propane to one part of residuum and asphalt precipitated therefrom at a temperature of 163 F. The remaining solution was then treated with an additional quantity of propane, about three or four volumes, to remove the resinous constituents at a temperature of around F.

The same procedure Was followed in the run in which caustic treatment was applied, the caustic treatment being applied before recipitation of the resinous constituents. A relatively strong caustic solution was used in this instance, consisting of 25% by'weight of caustic. The solution was used in the proportion of about 2.2

volumes to l volume of residuum.

The oil obtained by deasphalting and caustic treatment possessed the desiredgreen cast; also, as indicated, the treatment with caustic eiectively reduced the neutralization number.

In another example a Manvel residuum having the following tests:

was subjected to treatment in accordance with our invention. This involved first subjecting the residuum to deasphalting and deresinating by treatment with a volume of propane equal to twelve times the Volume of the residuum. This was carried out inl a countercurrent treating tower, the temperature at the top of the tower being 164 F. and the temperatureat the bottom being 163 F. In the course of this treatment the asphaltic and resinous materials were precipitated and removed simultaneously.

'Ihe propane solution of deasphalted and deresinated oil was drawn oil continuously from the top of the tower and then subjected to continuous treatment with approximately 77% by volume on the basis of charge oil of a 0.26% by weight aqueous solution of caustic soda, the eX- traction with caustic soda solution being carried out at a temperature of F. The caustic treated oil was then separated from the propane. It had the desired green cast and on testing was found to have the following tests:

Gravity, A. P. I 20.8 Flash 500 Fire 580 Vis/210 157 Color, Tag Rob 1/8 Pour F 30 Garbo-n residue, percent 1.84 Neutralization number 0.07

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should loe imposed as are indicated in the appended claims.

We claim:

1. The method of preparing lubricating oil suitable as cylinder stock, substantially free from asphaltic and acidic constituents and having a desirable green cast, from reduced naphthene base crude comprising diluting the oil with a liquefied normally gaseous petroleum hydrocar-V bon solvent, deasphalting the oil in the presence of said liqueed solvent and treating the oil without intervening treatment with inorganicacid with a large excess of dilute caustic soda solution in the presence of said liquefied solvent to remove the acidic constituents of the oil without substantially aecting adversely the constituents of the oil imparting the desired green cas-t.

2. The method of preparing lubricating oil suitable as cylinder stock, substantially free from asphaltic and acidic constituents and having a desirable green cast, from reduced naphthene base crude comprising diluting the oil with a liquefied normally gaseous' petroleum hydrocarbon solvent, deasphalting the oil in the presence of said liquefied solvent and treating the oil with about 0.2% to 0.5% caustic sodav solution in amount about 25 to `200% by volume inexcess of that required to neutralize the organic acidity and in the presence of said liqueed solvent to remove the acidic constituents of the oil Without adversely affecting the constituents of the oil imparting the desired green cast.

3. In the countercurrent treatment of lubricating oil stock derived from naphthene base crude petroleum with caustic soda solutionto remove organic acidity, the steps comprising diluting the oil with a liqueed normally gaseousv petroleum hydrocarbon solvent, continuously introducing the diluted mixture near the bottom of a packed tower Vlled substantially with dilute mixture maintained under pressure sufcient to `maintain the diluent liquefied, continuously introducingl -ing of sodium, potassium and' ammonium, the

steps comprising diluting` the oil with a liquefied normally gaseous petroleum hydrocarbon, charging the dilute oil near the bottom of a packed tower, charging the reagent near the top of said tower, maintaining the diluted oil under pressure suiiicient to maintain the diluent liquefied, maintaining the interface level between the reagent and the oil within the tower at a point intermediate the points of oil and reagent introduction to the tower, thereby causing the oil to flow through a substantial body of reagent within the lower portion of the tower, withdrawing used reagent and sludge from the bottom of the tower, and withdrawing the treated dilute oil from the top of the tower.

5. The method of preparing lubricating oil, suitable as cylinder stock, substantially free of asphaltic and acidic constituents and having a desirable green cast, from reduced naphthene base crude, comprising mixing the oil with a liqueiied normally gaseous petroleum hydrocarbon solvent in proportion sufficient to precipitate substantially all the asphalt, removing the asphalt in the presence of the liquelied solvent and treating the deasphalted oil, without subjecting it to an intervening treatment with inorganic acid and while still mixed with the liquefied solvent, with a I large excess of a dilute solution of a hydroxide selected from the hydroxides of the alkali group consisting of sodium, potassium and yammonium to remove the organic acidic constituents of the oil Without substantially affecting,adversely the constituents imparting said green cast to the oil.

6. The method according to claim 5 in which the vliquefied hydrocarbon comprises mainly propane.

7. 'I'he method of preparing lubricating oil, suitable as cylinder stock, substantially free from asphaltic and acidic constituents and having a desirable green cast, from reduced naphthene base crude, comprising mixing the oil with a liqueed normally gaseous petroleum hydrocarbon, deasphalting the oil in the precence of said liquefied solvent and treating .the oil, without an intervening treatment with inorganic acid, with a large excess of dilute caustic alkali solution in the presence ofsaid liqueed solvent to remove theorganic acidic constituents of the oil1without substantially aiecting adversely the constituents imparting the desired green cast.

8. The method according to claim 5 in which the resulting deacidied oil is treated with further liquefied solvent to remove resinous constituents.

9. In the method of preparing naphthene base cylinder stock of desirable green cast from reduced naphthene base crude and not requiring treatment with inorganic acid, the combination of steps which comprises diluting the residuum with a liquefied normally gaseous petroleum hydrocarbon capable of precipitating asphaltic constituents therefrom, subjecting the diluted mixture to settling to remove asphaltic constituents, treating the diluted mixture with a dilute hydroxide solution selected from the hydroxides of the alkali group consisting of sodirun, potassium and ammonium, said hydroxide solution being in large excess of the amount required to neutralize the organic acidity of the oil undergoing treatment, such that organic acidic constituents of the oil are removed Without substantially aiecting adversely the constituents imparting said green cast to the oil, and maintaining the dilute mixture during said deasphalting and alkali treating steps under pressure suficent tomaintain the diluent liquefied.'y

10. In the method of preparing naphthene base cylinder stock of desirable green cast from reduced naphthene base crude, the combination of steps which comprises diluting the reduced crude with a liqueed normally gaseous petroleum hydrocarbon, removing asphaltic constituents from the reduced crude in the presence of the liquefied diluent, and treating Vthe reduced crude inthe presence of the liquefied diluent with a dilute hydroxide solution selected from the hydroxides of the alkaliv group consisting of sodium, potassium and ammonium, said solution amounting to about 25`to 200% by'volume in excess of that required to neutralize the organic acidity of the oil and having an alkalinity approximately equivalent to a caustic soda solution containing around 0.2 to 0.5% by Weight of caustic soda. y

1l. The method of preparing lubricating oil,

suitable as cylinder stock, substantially free from asphaltic and acidic constituents and having a desirable green cast, from reduced naphthene base crude, comprising mixing the oil with a liquefied normally gaseous petroleum hydrocarbon solvent, maintaining the diluted mixture-under pressure suflicient to maintain the diluent liquefied, deasphalting the mixture of oil and liquefied diluent, and treating the dasphalted mixture of oil and liquefied diluent with a caustic alkali solution amounting to about 25 to 200% by volume in excess of that required to neutralize the organic acidity of the oil, said solution having a concentration of around 0.2 to 0.5% by Weight of caustic soda and such that organic acidic constituents of the oil are removed Without substantially affecting adversely the constituents imparting said green cast to the oil.

CHARLES T. ANNE.

HERMAN I. WILSON.

WILLIAM C. PATTERSON,

Images