US1749896A - Manufacture of lubricating oil - Google Patents

Description

Marchl 11? 1930. G. H, TABER, JR 1,749,896

MANUFCTURE 0F LUBRICTING OL original Filed Jan. 14 1925 ATTORNEYS Patented Mar. 11, 1930 UNITED STATES PAi'lzN'r;v OFFICE GEORGE H. TAZBER, JR.,'OF RYE, NEW YORK, ASSIGNOR T0 SINCLAIR REFINING PANY, or NEW YORK, N. Y.,

MANUFACTURE oF COM- A CORPOR-ATION OF MAINE f LUBRICATING OIL Original application led January A14, 1925, Serial No. 2,262. Divided and this application led May 26,

1928. Serial This invention relates to improvements in the distillation and refining of lubricating oils. The invention provides an improved method of producing lubricating oils from oils and distillates containing lubricating oil fractions, such as crude petroleum oil, topped crude oil, and crude lubricating oil distillates. The invention combined distilling and refining operation, improvements in the fractionation of oils and distillates containing lubricating oil for the separation of the desired lubricating oil fraction free from heavier and lighter components, an improved method of refining lubricating oils, and improvements in continuous distillation processes for the production of lubricating oilsl This application is a division of an application filed January 14, 1925, Serial No. 2,262.

Hitherto, in the methods generally employed for the production of lubricating oils from crude oil, the crude oil has been initially subjected to a fractional distillation, either by batch operations or in a series of continuous stills, and a broad lubricating oil distil late fractionV thereby separated from the crude oil; and this lubricating oil fraction has then been subjected to redistillation in the presence of caustic alkali introduced directly into the body of oil undergoing distillation for the production of refined lubrieating` oil distillates, the caustic alkali solution being employed to remove undesirable constituents such as naphthenic acids and asphaltic compounds which if allowed to distill y over the finished lubricating oil distillates Would render them bad colored and diiiicult to handle in further treatment. It has been proposed to apply the caustic alkali treatment directly lto the crude `oil undergoing distillation during the time in Which t-he broad lubricating oil fraction Was being produced, but such proposals have not been successful principally because of excessive deposition Within the still due to the accumulation of caustic alkali in the residuum andto the combined effect of such caustic alkali and impurities normally present in the crude oil.

The process of the present invention, as applied to the production of lubricating oils,

includes an improved s ing boiling range.

comprises continuous vaporization of the lubricating oil fractions from the crude lubricatlng oil-containing oil or distillate, treatment ofthe vaporized lubricating oil constituents vWith a caustic alkali, and subsequent condensation of the treated lubricating oil constituents.

According to the present invention, the yaporized lubricating oil constituents are subjected to treatment with caustic alkali While in the vapor phase. The alkali treatment of the lubricating oil fraction or fractions is thus effected before the lubricating oil constituents are condensed and in this Way redistillat-ion for treatment of the lubricating oils With caustic alkali is eliminated. Moreover, the refining operation, When carried out .in this Way, has several other important advantages. Thorough and intimate contact between the caustic alkali and the lubricating oil is effected and the refining action advantageously promoted. Likewise, the entire lubricating-oil distillate fraction is positively subjected to thorough treatment With the caustic alkali;'in vthe ordinary distillation With alkali the initially distilled components may escape Without thorough contact With the alkali. The caustic alkali treatment of the present invention is also combined advantageously with subsequent fractionating operations for separation of the desired lubricating oil fractions. The elimination of a distilling operation, particularly the crude distillation as ordinarily carried out, also assists in eliminating cracked products from the finished lubricating oil products. Cracked constituents are usually characterized by low viscosity as compared to their boiling point and are accordingly usually objectionable in lubricating oils of correspond- Other advantages of the invention Will be apparent from the following description.

In carrying out the present invention, the lubricating oil fraction may be vaporized from the crude oil or crude lubricating oil distillate in a vaporizing still and this vaporization may be keffected under atmospheric pressure or it may be effected under a subatmospheric pressure. The vaporization may vduced pressure.

vaporizing still through a fractionati-ng tower, or the operationof the vaporizing still may be controlled so that only the desired vapors of the desired lubricating oil fraction are produced. Where a fractionating tower is employed, it may be externally cooled or it may be cooled by introduction of a refluxing agent such as a portion of the distillate produced in the operation, and the fractionating tower may be arranged'to discharge refluxback into the still or the heavier .const ituents separated in the tower may be removed from the tower without being returned to the still. Vhere a fractionating tower is employed in connection with'the vaporizing still, the crude oil or crude lubricating oil distillate may be introduced into the tower and employed as a refluxing agent therein; andthe operation of the tower and'vaporizing still may be controlled so that vaporization of the desired lubricating oil fraction from the crude material introduced into the tower is substantially completed in the tower.

From the vaporizing still, or from the fractionating tower connected with the Vaporiz-V ing still,the vaporized lubricating oil constituents are conducted to a treating tower.

in which they are subjected to treatment with caustic alkali inaccordance with the present invention. Inthe treating tower, the liibri eating oil vapors are thoroughly and intimately contacted with a caustic alkali solution.

. The treating tower may be ofv conventional baffle tower construction arranged for introduction of the vapors into the lower part of the tower and of the treating solution into the upper part of the tower so that the lubrieating oil vapors are contacted in countercury rent flow with the caustic alkali solution. In

the treating tower, a part of theoil vapors are .condensed and the condensate mingles with the/used treatingsolution. rllhe caustic alkali content of the condensatey mixture may be employed for recirculation. through the tower for further treatment ofthe lubricating oil vaporspassing therethrough.y

The caustic alkali solution employed may,

for example, be an aqueoussolution of sodiumhydroxide of a densityof between aboutv 10 and 20 B. The minimum Iamount of j caustic alkalisolution employed should be at least suliicient to remove the undesirable constituents from the lubricating oil vapors loe-` Ving treated, but the maximum amount vemployed may vary widely as will appear hereinafter. -For example, the rate of introduction into the treating tewer of the sodium hy# droxide solutions just referred to may vary from 1/2% vapors entering to 15% or more on the weight of the treating'tower. Anexy cessk of the caustic alkali solution, over that Yeating oil distillate fractions produced, but

such an excess of treating solution mayproduce yan' increased cooling eect in the tower with the condensation of an increased proportion of the vapors therein. Condensation within the treating tower may by controlling the amount of treating solution introduced therein. Where l'an aqueous solution of caustic alkali is employed in the treatingtower, part of the water may be evaporated from the solution in the tower with resulting increase in concentration of caustic alkali in the solution, and the condensate mixture', including the yusedncaustic alkali solution and any condensate producedfin the treating tower, which accumulates mayconie prise a suspension of caustic alkaliv in oil in be regulated admixture with a more or less concentrated Y solution of caustic i alkali. This. mixture, with such additions of fresh causticalkali solution -as are necessary to replace alkali consumedin the treating tower, may be recycled through the tower for further treatment of the lubricating oilvapors passing therethrough. Before being recycled through the tower, a separation may be effectedV between the oil component of the mixture and the caustic alkali-containing component, and the separated caustic alkali containing componentof the mixture returned to the treating tower. After discharge from the treat# ing tower, the condensate mixture may be cooled and the oil component separated from kali solution to settle.

vaporized lubricating oil constituents pass therethrough without being condensed therethe vused causticalkali solution, for exampleA by decantation after allowing the caustic l in. For carrying out the operation in this",

way, the treating tower is thoroughly la to preventheat loss and the treating solution may be preheated before introduction into the For example, the condensate treating tower.

seed

mixture from the treating tower, ork the alkali containingconiponent of the condensate mix# ture, may be admixed withrfresh alkali solution without intermediate cooling and the mixture directly reintroduced into the tower.

lnfthis manner, the treating tower opera# Y isc tion can be controlled so that only a minimum Y proportion of heavier constituents is conn densed therein; Any lubricating oilY constituents condensed in the treating tower may Y be separated from the tower condensate mixture and recovered.

Before the vapors escaping from the treati;

ing tower are finally condensed, they 'are subjected to a fractionating operation. AThey may, for example, be passed througha fractionating tower in which the desired lubricating oil fractions are condensed and through which the constituents lighter than those desired in the lubricating oil fractions are allowed to pass uncondensed. This fractionating tower is employed in conjunction with the treatingtower for the production of a closely controlled lubricating oil distillate fraction by regulating the operation of the treating tower to condense heavier con stituents and by regulating the operation of the fractionating tower to permit lighter constituents to escape uncondensed therefrom. The uncondensed vapors escaping from the fractionating tower are condensed, for example,in an ordinary water cooled condenser.

The process of the present invention may be carried out in conjunction with a series of continuously operated. vaporizing stills in which akseries of progressively heavier fractions are treated for the separation of progressively heavier distillates, or through which the crude oil or crude lubricating oil distillate is successively passed with 'the vaporization therefrom of progressively heavier fractions in successive stills of the series. Where the vapors from several such stills are passed through treating towers in which they are subjected to treatment with caustic alkali in accordance with the present invention7 the oil component of the condensate mixture separated in towers operating on lighter vaporsmay be introduced into treating towers operating on heavier vapors with improvement of the fractionation effected in the several distillation stages. The caustic alkali associated with the oil in the condensate mixture from preceding treating towers may be introduced with the oil into successive treating towers and employed for treatment ofthe heavier vapors therein, or the caustic alkali component of the condensate mixture may be separated andfresh alkali supplied to successive treating towers.

vThe separated caustic alkali mixture may be reused inthe treating tower from which it is discharged.

The invention will be further described in connection with the accompanying drawings which illustrate, in a diagrammatic and conventional way, one form of apparatus adapted for the practice ofthe process of the invention; but it will be understood that this further description and illustration are intended for the purpose of exempliiication and that the invention is not limited thereto.

The apparatus illustrated comprises a vaporizing still 5, a fractionating tower 6, a. treating tower 7, another fractionating tower 55, and a cooler and condenser 8. The still illustrated is of the direct fire heated type and is provided with perforated pipes 9 for the direct introduction of steam into the body of oil in the still. The perforated pipes 9 are connected to a common header 10 which is in turn connected to a steam boiler. The still is also provided with a charging line 11 and a residue draw-olf 12. The fractionating tower 6 is arranged above the still. This tower is provided with a helical baiiie 13 and the vapors from the still pass upwardly through the helical passage in the. tower Vescaping from the upper end of the tower through the vapor line 14. Connections 15 and 16 are arranged near the upper end of the tower for the introduction of charging stock into the still through the tower or for the 1n troduction of a reiiuxing medium into the tower.

From the vapor line 14 the vapors en ter the treating tower 7, the tower shown being of conventional baflie construction, and pass upwardly therethrough about the baiiies 17 arranged in the tower. The second fractionating tower may also be of conventional baffle construction being provided with baiiies 56. A pump 18 is arranged to force caustic alkali solution into the upper end of the treating tower through connection 19 and the spray head 20 arranged in the upper end of the tower. The vapors escaping from the treating tower enter the lower part of the fractionating tower 55 through the vapor line 57 and pass upwardly therethrough over the batlies 56, escaping from the upper end of the yfractionating tower through the vapor line 58. The vapors escaping through the vapor line 58 enter the condensing coil 59 where they are cooled'and'condensed and discharged into a look box 60 which is provided with an outlet 61 for condensate and a vent 62 for uncondensed vapors and gases. The

fractionating tower 55 may be externally.

cooled or it may be cooled by the introduction of a suitable refluxing medium through connection 63 and the spray-head 64 arranged in the upper end of the tower. Where the fractionation is effected by the introduction of a refluxing medium, such as a partvof the condensed distillate, it may be improved by lagging the tower to prevent variable heat loss. The condensate collecting in the lower part ofthe fractionating tower 55 is discharged through connection 65 and the cooling coil 66 to the look box 67 which is provided with a condensate outlet 68 and a gas vent 69. For operation under reduced pressures, the gas vents 62 and 69 and the condensate outletsl and 68 may be connected to receivers and vacuum pumps and condensate pumps. The treating solution is supplied to the pump 18 through connection 31, which communicates with tank 32 throughy connection 33 having valve 34 therein and with tank 35 through connection 36 having valve 37 therein. The condensate mixture collecting in the lower part of the treating tower 7 is discharged through connection 38 to the tank-32. Connections are arranged and valves 39 and 40 are provided for discharging the condensate mixture from the treating tower to the tank 32 either through the cooling coil 41 and the connec-r tion 42 or through the by-pass connection 43 and the. connection 42. The connection 42 may include a pump 44 for returning the condensate mixture to the tank 32. T he tank 35 is provided for storing fresh caustic alkali caustic solution from the lower layer. AV

separation may thus be effected in the tank 32 between the oil and the used caustic solution of the condensate mixture, and as much of the used caustic solution as may be desired may be re-employed in the treating tower together with fresh caustic solution from the tank 35.

rIhe exposed parts ofthe still 5v and the fractionating tower 6 and the vapor line 14 are advantageously heat insulated or lagged to prevent unnecessary heat loss. .In order toj'pass thel maximum amount fof vapor through the vtreating 'tower7 .uncondensed, the treating towerv is valso `advantageously lagged or heat insulated.

Where the apparatus illustrated is einployed for vacuum distillation, the still 5,

the fractionating tower 6, the treating tower 7 and the fractionating tower 55 are suitably constructed and reinforced to prevent collapse under the excess of atmospheric pressure prevailing on ytheoutside over thereduced pressure within the distilling' apparatus, and suitable precautions are taken to prevent inleakage of air. The several vapor connections and the passages through the fractionating towers vand treatingV tower are also made of sufficient cross-sectional area so that the desired degree'of vacuum can be 'Y maintained without excessive consumption of power. l

In carrying out the processof the invention in the apparatus illustrated, the still- 5 is charged through the charging line 11 witoil or distillate containing the lubricating oil fractions. Thestill is heated andas vapors fromthe still rise through thel fractionating f tower 6 the feed of additional lubricating oil-containing` charging 'stock is begun lthrough connection 1,5. The'V distillation may be promoted by the introduction of' live steam directly into the body of oil in the still through connection 10.V lThe supply of additional charging stock through connection l5 may -be regulated to control the refluxing operation in the fractionating tower,V

and this `control may be supplemented by the introduction of a regulated amount of a fluxing agent through connection 16. The re-V fluxing agent employed may, for example, l

be oil separated'from the condensatey mixture collecting in tank 32, or part of the distillates or fractions of corresponding character.l

The fractionating operation is regulated lso p that the desired lubricating oilconstituents escape from the upper end of the fractionating tower 6 through the vapor line 14 and these lubricating oil vaporsenter the treat'- ing tower 7. ln the treating tower 7 the lubricating oil vapors are contacted in countercurrent flow Vwith a causticY alkali solution supplied to the upper end of the tower through spray-head 2O by means of the pump 18,. This caustic alkali solution may be fresh solution from the tank 35, or a solution or a suspension of caustic alkali withdrawn from the tank 32, or a mixture of the two.

The main portion of the Vlubricating oil vapors are passedthrough the treating tower with a minimum of condensation therein, and to this end the treating tower vis lagged and the circulation Vof treating solution through the tower is maintained at the minimum necessary to effect the desired refining oper- Y ation.` f The 'condensate mixture .from the treating Y 32 through the by-pass connection 43 without intermediate cooling, and caustic alkali solution for circulation through the treating" tower made up of ycaustic alkali withdrawn from the heated contents of the tank 32, alone ice tower 7 may also be run to the tank p or in admixture with fresh solution from the Y' tank 35, so that the treating solution entering the treating tower7 through the sprayi i head 20 is in effect preheated.

, rlhe lubricating'oil vapors escape from the treating tower through the vapor line 57, yto the second fractionating tower 55 where the vapors escaping form the treating tower are subjected to fractional condensation for the separation ofthe desired lubricating oily distillate fraction or fractions. The con-v densation in the tower 55 may be effected'by 'y external cooling or by the direct introduction of a cooling medium orv reiluxing agent through connection 63. lThe condensation .is i

controlledto condense thelubricating-oil constituents without condensing the vapor con- Vstituents lighter than the desired lubricating oil constituents. ln'this way, a lubricating'v Y oil distillate fraction free from lighter'con-fvr stituents is produced vdirectly as the .conden-y kgaten tower 55. rIhe operation 0f thg treat L i ing tower may be controlled toy separate hem;

ier constituents, and in an operation of this enter the second fractionating .tower and where lighter constituents are allowed to pass through the second fractionating tower uncondensed, a very narrow lubricating oil distillate fraction of the desired test qualities can be obtained directly, and further distillation or other treatment for refractionation or the separation of lighter constituents can be eliminated. Any lubricating oil constituents condensed in the treating tower collect in the tank 32 and may be withdrawn therefrom after separation from the caust-ic alkali solution therein.

The invention relates more particularly to operations in which fresh oil is supplied to the vaporizing still and residual oil withdrawn therefrom and in which a fraction of substantially uniform character is separated.

The operation may be carried Yout under substantially atmospheric pressure. It will be understood, however, that if the pressure in the receivers is approximately equal to atmospheric pressure the pressure in the still will be somewhat greater due to the resistance of flow of the vapors through the apparatus, but by suitably proportioning the cross sectional area of vapor passages through the apparatus to provide for free vapor flow this resistance and the consequent increase in pressure may be made substantially negligible. The still itself may be operated at atmospheric pressure, or at much lower pressures, by maintaining a suitably reducedA pressure in the receivers.

The temperature at which the lubricating oil vapors are contacted with the caustic alkali solution is not critical and no definite optimum temperature can be given as this will vary with the character of the lubricating oil fraction desired and the nature of the material to be treated. In general, the higher the temperature and more intimate thecontact, the smaller will be the amount of caustic alkali required.. Thus the most advantageous temperature to employ in the treating operation may be determined almost entirely by the tendency of the particular oil being treated to undergodecomposition in the distilling operation to such an extent that the lubricating properties of the oil will be impaired rather than by any optimum temperature of the vapors during contact with the caustic alkali solution.

No definite optimum pressure can be given, the effect ofV pressure during contact of the lubricating oil vapors and caustic alkali solution being so relatively unimportant that the most advantageous pressure is determined largely by the corresponding temperature it is desired to maintain in the distilling operation to vaporize the desired fraction without impairing its lubricating properties and the almost negligible resistance of the apparatus to the flow of vapors therethrough.

The following specific examples will serve as an illustration of temperatures and pressures that may be satisfactorily employed in the manufacture of lubricating oils in the illnstrated apparatus in accordance with the "present invention where the distillation is effected at substantially atmospheric pressure as well as under reduced pressure.

Crude lubricating oil-containing oil may be kcharged to the still 5 and heated to a temperature of about `680" F. therein. Vapors generated in the still will then pass successively through the fractionating tower 6, into which fresh oil may bevintroduced to control the fractionating operation so as to maintain a temperature of about 650 F. at the top of the fractionating tower, and then through the treating tower 7 and second fractionating tower 55 to the condenser 59. Steam may advantageously be introduced to the still 5 through connections 9 in an amount approximately equivalent to 80 lbs. per barrel of oil charged. Under the above conditions the pressure existing in the still as indicated at the bottom of the fractionating tower may be, for example, 4 inches of mercury above atmospheric pressure due to the frictional resistance of the apparatus to the flow of the vapors therethrough. The pressure at thetop yof the fractionating tower 6 may be reduced by this frictional resistance to about 3 inches of mercury above atmospheric pressure. A

into the top of the treating tower 7 at a rate corresponding to 1/2 lb. ofcaustic alkali per barrel of oil treated or slightly in excess of this amount. When operating the illustrated apparatus, as above described, the temperature of the vapors passing from the top of the treating tower 7 will be approximately 620 F. while the temperature of the liquid in the vbottom of the tower will be approximately l 630 F. The pressure in the treating tower` due to the frictiona-l resistance to vapor How may vary from a pressure of Vabout 2.8 inches of mercury. at the bottom of the tower to a pressure of about 1.5 inches of mercury at the top of the tower. The pressure will continue to drop along the vapor path to about 1.3 inches of mercury at the bottom of the second fractionating tower 55 and .5 inches of mercury at the top of the second fractionating tower. Fractionation Vof the treated vapors in the tower 55 may be advantageously effected by maintaining a temperature of approximately 480 F. at the top of the tower. The liquid temperature at the bottom of tower 55 would, of course, be somewhat higher, for example, about 550 F.

vIn the treatment of less refractory lubricating oil-containing oils, the lubricating properties of which might be impaired at the temperatures vemployed in the distillation underV solution of caustic alkali may be introducedI ioo Itheconditions above described, the distillation may advantageously be effected at re duced pressure. For example, the still 5 may be so operated as to maintain a pressure of 60 mm.-of mercury (absolute) at 4the bot- `tom of the first ractionating tower 6, the pressure decreasing along the path of vapor travel to about 50 mm. of mercury (abso-' lute) at'the top of the ractionating tower;

"fao

controlled so as to maintainateiiiperature.ofy

about 40 nim. Vor' mercury (absolute) `at the top of the treating tower`7; and about 35 mm. of mercury (absolute) at the top of the second fractionating tower.v Steam may beintroduced to the still 5 through connections 9 in an amount approximately equivalent to 20 lbs. per barrel of oil charged. The fractionatingoperation in the first ractionating tower f6' under such conditionsmay advanltageous'ly be so controlled by the introduc- 490D- F. at'the top of the treating tower v7. The second rac'tionating operation in tower 55 may to advantage be controlled sonas to maintain atemperatureA of about '350 F.at

the top 'o'f the tower when operatingunder the reduced pressure conditions above described. The process of the inventionfis of generalv application to lubricatingoilecontaining oils yand distillates. It may be applied to crude 'petroleums or to topped crude oilsfrom which lighter constituents, such vas gasoline, haveY been stripped. It is also applicable to the treatment of other oils and residues containinglubricating oil constituents, such as crude lubricating oil distillates and fractions. l'It i'n'ay be employedin thetreatment 'of oils of either asphaltic or paraiin'e base or 'mixed f `rbasevoi'ls. Following thedistillation and re- "iining treatment of the present invention, the lubricating oil distillate fractions may lbe filtered/through `fullers earth orsimilar material orsubjected'tosuch other'treatment as may 'be desired. Wax containing vdistillat'es,

waningoperations in the usual manner. In reiie'rring to "lubricating oils herein, reference fis madetolthejpetroleum oils characterized by Y ,'oiliness and'highviscosity. In general'these i oils maybedeiined as oils made up of constit- 'uents heavierthan gas oil,'having a 'gravity alkali. n

.Intestimony whereof, Ixhave l.subscribed GEORGE VAMBER, JR]

= myname.

the improvement which comprises continuously vaporizing lubricating oil constituents from a stockcontaining the same, continu-- ously taking off the lubricating oil vapors and subjecting them as such to treatment with` 'a caustic alkali solution, maintaining the temperature in this treatment to condense am minimum of lubricating oil constituents, con-k Y tinuously taking off lubricating oil vapors from this treatmentl free from alkali, and y' condensing a lubricating oilvfra'ction from the vapors'taken oit from'the alkali treatment, whereby said condensed lubricating oil fi'ractionvissubjected to the alkali treatment in the vapor phase but condensed out oi-con tact with the alkali. f j

Y 2. In'the manufacture of lubricating oils, the improvement which comprises continuously vaporizing lubricating oil constitue-nts 'tromfa stock containing the same, continuousl lyftaki'ng oil" the lubricatingoil vapors and.l

subjecting them to a fraction'ating operation for condensation of heavier constituents,

'continuously' taking oft' the lubricating oil vapors from the'fractionating operation and subjecting them as such to Vtreatment with a ycaustic alkali solution, maintaining the temperature in this treatment to-condense a miniymuni o/f-'lubricating oil constituents, continu. Y

`ously taking oi Vlubricating oil vapors from 1 "thistre'atinent` free from alkali, and 'condens- :ingza lubricating oil'fraction from the vapors takeno from the alkali treatment, whereby said 'condensed lubricating oil fraction is sub.-

j'ected to the alkali'treatment in the 'vapor phase but condensed out of contact withfthe 'K V14liio ttor example, may be subjected tosuitable delower than about`35 B. anda viscosity up- .i

of `about '50'at 100 F. Saybolt vers-al.,

SI claim-- j l f Uni- CERTIFICATE 0F CORRECTION.

Patent No. 1,749,896. Granted Marcil ll, 1930, to

GEORGE H. TABER, JR.

It is hereby certified that error appears in the printed specification of the above numbered patent'requiring correction as fol-lows: Page 1, line 36, after the word "over" insert the word "with"; page 4, lines 72 and 73, for the word "fluxing" read "refluxing", and line 114, for "form" read "from"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 8th day of April, A. D. 1930.

M. J. Moore, (Seal) Acting Commissioner of Patents.

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