US2028361A - Process for producing lubricating oils - Google Patents

Description

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PROCESS FOR PRODUCING LUBRICATING OILS Patented Jim'. 21, 193.6v

PATENT yll`2,023,361

oFFicE i rnocsss Fon Pnoilggma Luarca'rmo.

John V. Starr and David F. Edwards, Elizabeth, N. J., assignors to Standard Oil Development Company, a corporation of Delaware.

' Application :une zo, 1931, seran No. 545,693

2 Claims. (Cl. 196-79) This invention relates to a' process for producing nished lubricating oils of high color and good cast from a lubricating oil stock treated with a selective solvent. 'Ihe .invention will be fully understood from the following description read y in commotion with the drawing, the sole gure of which is a diagrammatic side elevation, partly in section, showing one form of the apparatus used for carrying out the invention.

When producing lubricating oils .by extraction with selective solven'ts such as phenol, aniline, furfural, etc., it is customary to subject the raffinate to distillation or to agitate it with a suitable washing medium in order to remove the solvent from the' treated oil. 'Ihe general appearance of the lubricating `oil thus obtained from an originally low grade distillate is distinctly inferior and .necessitates a iinishing procedureof some kind. The object of the present invention is to provide a iinishing procedure whereby the solvent is separated from the raflinate and vat the same time 'a fln'ished lubricating oil of any desired viscosity is 'obtained possessing high color and ex cellent'appearance' when viewed in reflected light. After treating mineral oil or a distillate with selective solvents the treated oil layer usually contains from to 20% of the solvent depending on the solvent employedand the temperature of the treat. We have found that by mixing a small quantity, say 5/8 lb. to 1 1b. per gallon of adsorbent clay. such as fullers earth or an acid A treated er activated clay, withthe. treated oil,

subjecting the mixture of oil and clay to dis` tillation so as to remove the solvent with the lighter oils and subsequently separating the clay .from the residual oil, not only the separation of the selective solvent from the lubricating oil is obtained, but simu1taneously,a finished lubricating oil product is produced which has excellent colr and cast. 'I'he distillation may be carried out either in a shell still or in a pipe still or in a combination of a shell still and a pipe still or two pipe stills, as will be understood hereinafter.

In some cases it may be desirable or economical toY recover part oi'v the solvent from the treated oil by means other than distillation, such as, for example, by washing, or it may be economical to distill olf the maior portion (say 90%) or even more of the solvent in a shell still thenadd theclay to the residual oil and submit thelatter to ldistillation in a pipe still in the presence oi' clay.

The preferred operation, however, is the following: 55.

. The vraiiinate containing some solvent ismixed withv agitation with the necessary quantity oi' fullers earth or an activated clay and the slurry thus obtained is passedthrough heat exchangers and thenv through the heating coil of a pipe still where it is heated to a .temperature suiiiciently 5 high to vaporize most of the solvent. The hot oil and clay mixture is then discharged into the vaporizing zone of a bubbletower held under substantially atmospheric pressure. The solvent will be taken off as an overhead product from the tower, and is condensed and returned to storage for further use. The bottoms from the atmospheric tower are further heated by passage through a separate heating coil placed in a furnace or by other suitable means to such a temperature as to vaporize the lighter portions of the oil and insurel the removal of any remaining solvent.l The hot bottoms containing the clay are then flashed into the vaporizing 'zone of a bubble tower heldunder high vacuum. The'remaining solvent together with some light oil is obtained as overhead product from the vacuum tower, spindle oils or light motor oils are taken out as upper side stream, heavier motor oils as lower side stream and cylinder oil or heavy motor oil containing spent clay is ywithdrawn as bottoms, cooled and passed through a filter press to remove the clay. The procedure may be varied to produce oils of any desired viscosity. The`apparatus for this preferred operation is shown in the drawing. v

Referring now to the drawing, numeral I designates an oil storage tank, 2 a'. treater for treating the oil with a selective solvent, 3 the storage tank for the extract and 4. 'the storage tank for the treated oil. The hopper 5, mixing tank 6 and mixer 'I serve for the admixture ofdecolorizing clay to the treated oil. Pump 8, heat exchangers 9, III and .tube still Il, serve for passing and heating the oil clay slurry into the vaporizing and fractionating tower I1. The overhead product (treating solvent) is removed through line- I3. condensed in'condenser I4 and stored in tank I5 from which it may be pumped by means of pump I8 into treater 2. The residue of distilla- I tion is removed from tower I2 through line Il 45 and passed by means of pump I8 through tube still I9 and line 20 provided with the Vpressure reduction valve into the vacuum towerZI. The overhead product leaves the vacuum tower, through line 22 and is condensed in condenser 23. Means such as vacuum steam jet pumps 24 or any other known means are provided for maintaining the necessary vacuum.' Lines 25 and 26 serve for removing' the side streams through heat exchangers I and I0. respectively. The residue 5I and is pumped by means of pump 28 through.

` each case removed as before.

' .The b`ulk ofthe rainate with the 12% phenoll from the vacuumtower leaves through line 21 cooler 29 and filter press 30 to separate the spent clay from the treated reslduum.

ess.

A crude lubricating distillate from Colombia having gravity of 21.8 A..P. I., viscosity of 63 at 210 F. and viscosity index of 43 (determined by the method described in the article of E. W. Dean and G. H. B. Davis, Chemical and Metallurgical Engineering, volume 36, No. 10, October 1929), was

treated with 50% by volume of 100% phenol at 108 F. After agitation for about ten minutes the mixture was allowed to stratify and the extract layerwithdrawn. Five additional dumps of phenol each 50% by volume of the oil beingk treated were applied and the extract layers in A rafilnate yield of63.7% was obtained. A sample of the rainate which showed 12% phenol was dephenolized by distillation, yielding dephenolized oil 56% of charge. The phenol free oil had a gravity of 27.7 viscosity of 59 seconds Saybolt at 210 F. a viscosity index of 88, but low Robinson color.

content was placed in an agitator heated at 11G-120 F. and mixed with 1/2 lb. per gallon of an activated adsorbent clay. The oil clay slurry was then fed through a heating coil where the temperature was raised to 557 F. and flashed into the vaporizing chamber of Va bubble tower, kept substantially under an absolute pressure of 20 mm. mercury. Substantially. all of the remaining solvent was taken overhead together with a relatively small amount of gas oil, a portion of the overhead being returned to the tower as reflux. .The bottoms amounting to 78% of the charge were withdrawn, partially cooled (to about Qualitative tests in the bottoms showed no phenol present.

As a second example of carrying out our invention samples of the phenol treated Colombian oil described above were partially dephenolized ,l by washing with NaOH solution, the major portion (about of the phenol being washed out. The residual oil amounting to about 89% of the original rainate was blown bright at F., mixed with clay at about 120 F., passed through the heating coil of a pipe still where it was heated to a temperature of 675 F., and flashed into the vaporizing zone of the bubble tower held at an absolute pressure of 17-18 mm. of imercury, a portion of the overhead being returned to the tower as reflux.

Two similar experiments were carried out. In one case the sample of'residual oil from the first still was mixed with 1A lb. per gallon of acid treated clay and distilled in a pipe still, 83% being taken overhead and 17% vobtained as bottoms.` In the other case 1,/4 lb. per gallon of finely powdered A ttapulgus clay was added to the oil and distilled in the pipe still to obtain 80.3% of overhead products and 19.7% of bottoms. The

The following examples will illustrate our proci bottoms of both experiments were cooled and filtered, yielding cylinder oils with the following inspection:

In both cases, the color stability as tested by 15 maintaining the oil at a temperature of 212 F.` for sixteen hours, was very good, and the general appearance of the yoils viewed by reflected light showed a desirable olive green cast. The overhead products were rerun giving Spindle oil, light machine oil and motor oil of good quality.

In the following claims, the expression selective solvent is meant to designate solvents of the type of phenol, aniline, furfural, etc., which when brought in contact with the oil, selectively absorb certain undesirable constituents of unsaturated and/or aromatic character. The expression is not meantq to include agents which have a chemical action on the constituents of the oil such as, for example, sulfuric acid, which not only absorbs certain constituents, but also causes polymerization and sludge formation, or other treating agents such as aluminum chloride, zinc chloride, iron chloride, and' solutions thereof 35 which cause polymerization or condensation reactions with certain constituents of the oil.

This invention is not to be limited by any theory or by the examples given by way of illus-v tration, but only by the appended claims in which 40 it is our intention to claim all inherent novelty of our process.

We claim:

1. Process of preparing lubricating oil from a lubricating oil stock which comprises agitating the stock with a selective solvent, separating the extract layer from the rainate layer, subjecting the ramnate layer in the presence of the absorbed selective solvent which it containsy at the time of its separation from the extract layer to fractional distillation in the presence of an adsorbentclay, and removing the adsorbent clay 'from the distillation residue.

2. The process of preparing lubricating oil from a. lubricating oil stock which comprises treating said stock by agitation with'a selective solvent, separating the extract layer from the raffinate. layer, mixing said raffinate layer with an adsorbent clay in the presence of the absorbed se- 60 lective solvent which it contains at the time of its separation from the extract layer to obtain a slurry, passingthe slurry through an elongated narrow heating zone into an enlarged combined vaporizing and fractionating zone held under ate5 mospheric pressure, removing substantially all of the solvent and a part of the oil as distillate, passing the' residue through a second elongated narrow heating zone, discharging the heated residue into an enlarged combined vaporizing and fractionat- 70 ing zone held under vacuum to obtain at least one distillate and a second residue, and separating the clay from the second residue.

JOHNI V. STARR.

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