US1698076A

US1698076A - Manufacturing of lubricating oil

Info

Publication number: US1698076A
Application number: US2262A
Authority: US
Inventors: Jr George H Taber
Original assignee: Sinclair Refining Co
Current assignee: Sinclair Refining Co
Priority date: 1925-01-14
Filing date: 1925-01-14
Publication date: 1929-01-08
Anticipated expiration: 1946-01-08

Description

Jana 8, i

G. H. TABER. JR

MANUFACTURING OF LUBRICATING OIL Filed Jan. 14, 1925 2 sheets-sheet 1 Jan. 8, 1929.

G. H. TABER. JR

MANUFACTURING OF LUBRICATING OIL Filed Jan. 14, 1925 2 Sheets-Sheet 2 Patented Jan. s, 1929.

UNITED STATES GEORGE H. TABER, JB., OF RYE,

vPANY, 0F NEW YORK, N. Y., A

NEW YORK, ASSIGNOB '10 SINCLAIB BEFINING Coli- CORPORATION 0F MAINE.

IANUFACTRING 0F LUBRICATING OIL.

Application led January 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 includes au improved combined distilling and refining operation, improvements in the fractionation of oils and distillates containing lubricating oil for the separation of the desired lubricatingr 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 oils.

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 by batch operations or in a series of continuous stills, and a broad lubricating oil distillate 'fraction thereby separated from the Vcrude oil; and this lubricating oil fraction has then been subjected to ledistillation in the presence of caustic alkali introduced directly into the body of oil undergoing distillation for the production of refined lubricating oil distillates, the caustic alkali solution being employed to remove undesirable constituents such as naphthenicacids and asphaltic compounds which if allowed to distill over with the finished lubricating oil distillates would render .them bad colored and difficult to handle in further treatment. It has been proposed to apply the caustic alkali treatment directly to the crude oil undergoing distillation during the time in which the 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 and to the combined effect of such caustic alkali and impurities normally present in the crude oil. Y

It is one of the objects of the present invention to eliminate the initial distillation for the separation of a broad lubricating oil distillate fraction as is commonly practlced. Further objects of the invention include the provision of several important improvements in methods of producin lubricating oils as will more fully a pear liereinafter.

The process o theopresent invention, as

distillation, either.-

14, 1925. Serial N0. 2,262.

applied to the production of lubricating oils, comprises vaporization of the lubricating oil fractions from the crude lubricating oil-containing oil or distillate treatment of the vaporized lubricating oii constituents with a, treating agent, more particularly caustic alkali, and recovery of the treated lubricating oil constituents.

According to the present invention, the vaporized lubricating oil constituents are subjected to treatment with caustic alkali while primarily in the vapor phase, and any condensate for 'ed in the treating operation is also subjecte to treatment in the li uid phase. ,The alkali treatment of the lubricating oil fraction or fractions is thus effected before or as the lubricatin oil constituents are condensed and in t is way redistillation for treatment of the lubricatin oils with caustic alkali can beeliminated. oreover, the rej fining operation, when carried out in this way, has several other important advantages. Thorough and intimate contact between the caustic alkali and the lubricating oil can be 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 the ordinary distillation with alkali the initiall distilled components may escape without tliorough contact with the' alkali. The caustic alkali treatment of the present invention also may be combined advantageously with a fractionating opera.- tion for separation of the desired lubricating oil fractions. The elimination of adistilling 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 c aracterized by low viscosity as compared to their boiling point and are aecordingly usually objectlonable in lubricating oils of corresponding boiling ran e. Other advantages of the invention will apparent from thefollowing description.

In carrying out the present invention, the lubricating oil fraction may' vaporized from the crude oil or crudel lubricating oil distillate in a vaporizing still and this va.- porization may be eiected under atm heric pressure or it may with advantage be e ected under a subatmospherc rassure. -The va` porization may be carrie out with or without the introduction Aof steam or an inert gas.

- kali content of the condensate One advantageous way to carry out the vaporization is with the introduction of steam and under reduced pressure. After vaporization, the vaporized lubricating oil constituents may be subjected to a fractionating operation, for example, by passino the vapors from the vaporizing still through a fractionating tower, or the operation of the Vaporizing still may be controlled so that only the desired vapors of the desired lubricating oil fraction are produced. lVhere a fractionating tower is employed, it may be externally cooled orit may be cooled by introduction of a reliuxing agent such as a portion of the distillate produced in the operation; and the fractionating tower may be arranged to discharge reflux back into the still or the heavier constituents separated in the tower may be removed from the tower without being returned to the still. Where 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 reiuxing agent therein; and the 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 Vaporizing still, the vaporized lubricating oil constituents are conducted to a treating tower in which they are subjected to treatment with caustic alkali in accordance with the present invention. In the treating tower, the lubricating oil vapors are thoroughly and intimately contacted with a caustic alkali solution. The treating tower may be of conventional bale tower construction arranged for introduction of the vapors into the lower Apart of the tower and of the treating solution into the upper part of the tower so that the lubricatin oil vapors are contacted in counter current ow with the caustic alkali solution. In the treating tower, apart of the oil va ors are condensed and the condensate ming es with the used treating solution. The caustic almixture may be employed for recirculation through the tower efor further treatment of the lubricating oil vapors passing therethrough.

The caustic alkali solution employed may, for example, be an aqueous solution of sodium hydroxide of a density of between about 10 a 20 B. The minimum amount of i v caustic alkali solution employed should be at least ',suiicientto remove the undesirable constituents from the lubricating oil vapors ing treated, but the maximum amount employed ma vary widely as will appear hereinafter. or example, the rate of introduction into the treating tower of the sodium vhydroxide solutions just referred to-fmy vary from 1/2% to 15% or more on the weight of vapors entering the treating tower. An excess of the caustic alkali solution, over that required to eli'ect the desired refining operation, does not injure the quality of the lubricating oil distillate fractions produced, but such an excess of treating solution may produce an increased cooling efl'ect in the tower with the condensation ot an increased proportion of the vapors therein. Regulation of the condensation within the treating tower by controlling the amount ot' treating solution introduced therein is employed with advantage in certain ways of carrying out the process of the invention. lVhere an aqueous solution of caustic alkali is employed in the treating tower, part of the water may be evaporated from the solution in the tower with resulting increase in concentration of caustic alkali in the solution,fand the condensate mixture, including the used caustic alkali solution and any condensate produced in the treating tower, which accumulates may comprise a suspension of caustic alkali in oil in admixture with a more or less concentrated solution of caustic alkali. This mixture, with such additions of fresh caustic alkali solution as are necessary to replace alkali consumed .in the treating tower, may be recycled through the tower for further treatment of the lubricating oil vapors passing therethrough. Before being recycled through the tower, a separation may be effected between the oil component ot' the mixture and the caustic alkali-containing component, and the separated caustic alkali containing component of the mixture returned to the treating tower. f

By appropriately regulating the cooling effected in the treating tower, for example by controlling the amount of treating solution circulated through the tower, a lubricating oil distillate fraction may be separated from the vapors in the treating tower. A lubrieating oil fraction may similarly be separated in the treating tower by externally cooling the tower. After discharge from the treating tower, the condensate mixture may be cooled and the lubricating oil fraction separated from the used caustic alkali solution, for example by decantation after allowing the caustic alkali solution to settle. In this way, a refined lubricating oil fraction, free from the lighter vapors which escape through the treating tower uncondensed, can be produced in the treating tower. Tn 'such an operation,

additional caustic alkali is employed with adfractionating tower thereon, a closely conj:

promoting the condensationin ample, the condensate mixture from the treating tower, or the alkali containing component of the condensate mixture, may be admixed with fresh alkali solution without intermediate cooling and the mixture directly reintroduced into the tower. In this manner, the treating tower operation can be controlled so that only heavier constituents are condensed therein and so that only a minimum proportion of such heavier constituents are condensed. Any lubricating oil constituents condensed in the treating tower may be separated from the tower condensate mixture and recovered.

The uncondensed vapors, escaping fronr the treating tower are condensed, for example in an ordinary vwater cooled condenser. Where the main portion of the lubricating oil fraction is separated in the treating tower, the condensate from the vapors escaping from the treating tower comprises the lighter constituents uncondensed in the treating tower. 'lVhere the treating tower is operated to condense a minimum proportion of the lubricating oil fraction, the condensate from the vapors escapingr from the treating tower comprises the lubricating oil distillate fraction. Where the vaporized constituents escaping from the still. or from the fractionating tower on the still, include constituents lighter than those desired in the lubricating oil fraction, this final condensate also includes such lighter constituents and may be sub-l 'ected to further treatment for the separation of these lighter constituents therefrom. The vaporizing operation and the initial fractionating operation, however, may be controlled so that the final condensate'produced from the vapors escaping from the treat-ing tower is the desired lubricating oil distillate fraction.

Before the vapors escaping from the treating tower are condensed, they maybe subjected to a further fractionating operation. They may, for example, be passed through a second fractionatng tower in which the desired lubricating oil fractions are condensed and through which the constituents lighter than those desired in the lubricating o'il fractions are allowed Lto pass uncondensed. Such a second fractionating tower may be employed in conjunction with the treating tower for the production of a closely controlled lubricating oil distillate fraction by regulating the operation of the treating tower to condense heavier constituents and by regulating the operation of the second fractionating tower to permit lighter constituents to escape uncondensed therethrough. .Where such a second fractionating tower is emloyed, a heavier lubricating oil fraction may e separated in the treating tower and a lighter lubricating-- oil fraction, which however is free from the lightest undesirable constituents,'can be separated in the fractionatingtower.

The process of the present invention may be carried out 1n conjunction with a series of cntinuously operated vaporizing stills iny which a series of progressively heavier fractions are treated for the sepa-ration 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 invention, the oil component of the condensate mixture separated in towers,operating on lighter vapors may 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 succesive treating towers and employed for treatment of the heavier vapors therein, or the caustic alkali component of the condensate mixture may be separated and fresh alkali supplied to successive vtreating towers. The separated caustic alkali mixture may be reused in the treating` tower from which it is discharged. k

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

In the accompanying drawings:

Fig. 1 represents, in elevation and partly in section, an apparatus adapted for carrying out the process of the invention,

Fig. 2 is a similar view showing a inodified arrangement of apparatus for carrying out the process of the invention, and' Fig. 3 represents an apparatus for carrying out the process .of the invention 1n a continuous manner.

izo

CII

The apparatus illustrated in 1 comprises a vaporizing still 5, aF fractionating tower 6, a treating tower 7 ,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 1() which is in turn connected to a steam boiler. The still is also provided with a charging line 11 and a residue drawoff 12. The fractionating tower 6 is arranged above the still, the tower illustrated being of the general construction described and illustrated in an application of John E. Bell, filed April 1, 1924, Serial No. 703,338. This tower is provided with a helical baiie 13 and the vapors from the still pass upwardly through the helical passage in the tower escaping 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 introduction of a rcluxing medium into the tower.

From the vapor line 14 the vapors enter the treating tower 7, the tower shown being of conventional baiile construction, and pass upwardly therethrough about the baffles 17 arranged in the tower. 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 rising through the treating tower escape lthrough the vapor line 21 to the condensing coil 22 from which condensate is discharged through the look box as into the receiver 24. The look box is provided with a gas vent 25,

` and, in operating at approximately atmospheric pressure, the valve 26 is closed and the valve 27 opened, any gases escaping through connection 28. The condensate may be Withdrawn from the receiver by means of pump 29 or may be discharged through connection 30. The treating solution is supplied to the pump 18 through connection 31, which communicates with tank 32 through 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 thfcoolin coil 41 and the connection 42 or through the y-pass connection 43 and the connection 42. The connection 42 may include a pump 44 for returning the condensate mixture to the tank 32. The tank 35 is provided for storing fresh caustic alkali solution and is provided with, a charging connection 45.

Ther condensate mixture returned tothe tank 32- from the treating tower may be recirculated through the treating tower by means of pump 18, or a separat-ion of condensate and treating solution may be e'ected in the tank 32. The oil condensate is lighter than the admixed caustic alkali solution and tends to float thereon; and connection 46 is provided for withdrawing separated oil from the upper layer collecting in the tank and connection 47 for withdrawing used caustic solution from the lower layer. A separation may thus beefected 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 reemployed in the treating towertogether with fresh caustic solution from the tank 35.

The exposed parts of the still 5 and the fractionating tower 6 and the vapor line 14 are advantageously heat insulated or lagged to prevent unnecessary heat loss. Where it is desired to pass the maximum amount of vapor through the treating tower 7 uncondensed, the treating tower is also advantageously lagged or heat insulated. Where, however, it is desired to separate a fraction from the vapors in the treating tower the treating tower may be exposed to the atmosphere for cooling the elfectcondensation of the desired fraction..

Where the apparatus illustrated in Fig. 1 is employed for vacuum distillation, the still 5 and the fractionating tower 6 and the treatu ing tower 7 are suitably constructed and reinforced to prevent collapse under the excess of atmospheric pressure prevailing on the outside over the reduced pressure within the distilling apparatus, and suitable precautions are taken to prevent inleakage of air.

nThe several vapor connections and the passages through the fractionating tower and treating tower are also made of suicient cross-sectional area so that the desired degree of vacuum can be maintained without excessive consumption of ower. For maintenance of subatmospherlc pressures within the distilling system, the vacuum pump 48 is arranged for exhausting uncondensed vapors and gases and the pump 29 is employed' for removing condensate from the system. For operation under reduced pressures the valve 49 in the connection 30 andthe valve 27 in the connection 28 are closed. The gases and uncondensed vapors separated in the look box 23 are withdrawn through connection 50 and any gases and uncondensed vapors c ollecting in the u per part of the receiver 24 are withdrawn t rough the connection 51 by means of the vacuum pump. Where the apparatus is operated under a vacuum, the valve 52 in connection 42 isclosed and the pump 44 is employed for returning the condensate mixture from the treating tower 7 to the tank 32.

connection 10. The supply of additional charging stock through connection may be regulated to control the reiiuxin operation in the fractionating tower, an this control may be supplemented by the introduction of a regulated amount of areuxing agent throu h connection 16. The refluxing agent emp oyed may, for example, be oil separated from the condensate mixture collecting 1n tank 32, or part of the distillate collecting in the receiver 24, or fractions of corresponding character. The fractionating operation is regulated so that the desired lubricating oil constituents escape from the upper end of the fractionating tower 6 through the vapor line 14 and these lubricating o1l vapors enter the treating towers 7. In the treating tower 7 the lubricating oil vapors are contacted in countercurrent flow with a caustic alkali solution supplied to the upper end of the tower through spray head 20 by means of the pump 18.P This caustic alkali solution may be fresh solution from the tank 35, or a solution or a suspension'ofcaustic alkali withdrawn from the tank 32, or a mixture of the two.

For the separation of a lubricating oil fraction in the treatino` tower, the circulation of treating solution through the tower -is regulated to edect condensation therein of the desired lubricating oil constituents. -The condensation effected by the treating solution,L and by evaporation of water from the solution where an aqueous solution is employed, may be supplemented by external cooling of the treating tower. Where the condensate mixture or part of the condensate mixture is recirculated through the treating tower the condensate mixture may be cooled by circulation through the cooling coil 41Von its way to the tank 32. After separation from the used caustic solution in the tank 32, the lubricating oil fraction condensed in the treating tower 7 is withdrawn Lthrough connection 46,.. and may be subjected to further settling or washing treatment or other suitable treatment for the separation of any remaining admixed caustic alkali. f

For circulating bricating oil vapors through the tower with a minimum of condensation therein, `the treating tower is lagged and the circulation of treating solution through the tower is the main portion of the lu! maintained at the minimum necessary to ef- `fect the desired refining operation. The conthe treating solution entering the treating tower 7 through the spray-head 20 is in effect preheated. ,The lubricating oil vapors escape from the treating tower through the vapor line 21 and are condensed and collected in the receiver 24. Where the operation is carried out continuously in this manner, the condensate collecting in the receiver 24 may include, in addition to the lubricatin oil constituents, some lighter constituents w ich may be removed by further treatment. Any lubricating oil constituents condensed in the treatin tower collect in the tank 32 and may be wit idrawn therefrom after separation from the caustic alkali solution therein.

The two preceding paragraphs relate 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 process of the present invention is also applicable where the distillation is carried out upon successive charges of oil with the successive separation of progres sively heavier cuts either in the treating tower or in the condenser or in both. The operation, for example, may be carried out by char-ginfr the still with -oil and progressively distilling oil therefrom, permitting lighter constituents undersirable as lubricating oil constituents to escape through the 'treating tower, beginning the introduction of caustic alkali solution into the treating tower as lubricating oil constituents begin to come over, and separating the distillate into the desired cuts.

The operation may becarried out under substantially atmospheric pressure. It will be understood, however, that if the pressure in the receiver 24, for example, is approximately equal to atmospheric pressure the pressure in the still will be somewhat greater due to the resistance of How 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 How this resistance and the consequent increase in pressure may be made substantially negligible. The still itself may be operated Aat atmospheric pressure, or at much lower pressures by maintaining a suitably reduced pressure in the receiver 24. For this purpose the vacuumpump 48 and the condensate pump 49 are provided for exhausting uncondensed vapors and gases and in Fig. 1.

condensed distillate, respectively, from the distilling system. Where the operation is carried out as a batch operation -upon successive charges of oil with separation of' the distillate into progressively heavier cuts, re-

duced pressures may be employed with advantage for eliminating light undesirable constituents from the lubricating oil fractions, and in carryingout the process of the invention the lubricating oil distillate can be separated into narrow fractions by regulating the operation of the still, of the fractionating tower, and of the treating tower in accordance with the invention. l

The apparatus illustratedin Fig. 2 is of the same general construction and arrangement as that illustrated in Fig. 1, differing principally in the provision of a second fractionating tower 55.1v In Fig.'2 the same parts as appear in Fig. 1 are designated by the same reference character withthe letter a appended. The second fractionating tower `55 is of conventional baille construction being provided with baffles 56. Vapcrs from the top of the treating tower 7 'enter the lower part of the fractionating tower 55 through the vapor line 57 and pass upwardly therethrough over the baes 56, escaping from the upper end of the fractionatigig 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 loutlet 61 for condensate and a vent 62 foi' uncondensed vapors and gases. The fractionat-ing tower 55 may v be externally cooled vor it 'may be cooled by the introduction of a suitable refluxing medium through connection 63. and the sprayhead 64.arranged in the upper end of the tower. Where the fractionation is effected by the introduction of a reluxin medium, such as a part of the condensed dlstillate, it may be improved by laggin the tower to prevent variable heat loss. e condensate collecting in the lower part of the fractionatin tower 55` is discharged through con.- nect1on` 65 and the coolino.' coil 66 to the look box 67 which is provided.a with a condensate outlet 68 and a gas. vent 69. For operation under reduced pressures, the gas vents 62 and 69 and the condensate outlets 61 and 68 may be connected to receivers and vacuum pumps and condensate pumps as has been described in connection with the apparatus illustrated In carrying out the process of the invention in the apparatus illustrated in Fig. 2, the operation of the still 5a and fractionating tower 6i is much the same as has been described in connection with Fig. 1. The still may, however, be operated at a somewhat increased rate where fractions are taken out of the vapors in both the treating tower and the second fractionating tower. The operation of the treating tower 7 likewise may be carried out in much the same way as 'has been described in connection with Fig. 1.

In the second fractionating tower 55, the vapors escaping from the treating tower are subjected to fractional condensation for the separation of the described lubricating oil distillate fraction. The condensation in the tower may be effected by external cooling or by the direct introductlon of a cooling medium or refluxing agent through connection 63. The condensation is controlled to condense the lubricating oil constituents 4withoutcondensin the vapor constituents lighter than' the'tesired lubricating oil constituents.

In this way, a lubricating oil distillate fraction free from lighter constituents is prouced directly as the condensate in tower 55. .The operation of the treating tower may be controlled to separate heavier constituents, and in an operation of this character, where heavier constituents are separated before the lubricating oil vapors enter the second fractionating tower and where lighter constitu- '90 ents are allowed to pass through the second fractionating tower unconden'sed, a very narrow lubricatlng 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. Another and a heavier Lubricating oil distillate fraction can also be separated from the vapors in the treating tower; in' the same operation.

The apparatus ill ratedin Fig. 3 is arranged `-for continuo s operation with separation of a plurality of cuts or fractions in each of a.v series of stills, and comprises a series of stills, fractionatin towers, treatin(7 towers and' condensers eac of the generaal construction and arrangement illustrated in Fig. 1. While the apparatus illustrated comprises three stills, it will be apparent that a greater or lesser number could be employed for the separation of a greater or lesser number of fractions. In the three stills shown` the same parts as are shown in Fig. 1 are designated -by the same reference character, with b appended in the first still 5, with c appended in the second still 5c, and with df .appended in the third still- 5d. Secondary fractionating towers 55h, 55 and 55d corresponding to the secondary fractionating tower 55 in the apparatus illustrated in Fig. 2 may be similarly associated with each of the stills in the series illustrated in Fig. 3, if desired.

- In Fig. 3, a connection 70 includin a pump 71` is provided for withdrawing residual oil from the still 5" and introducing it into the tower 6c on the still 5, and a connection 72 includinga pump 73 is provided for withdrawing residual oil from the still 5c and introducing it into the tower 6i on the still 5d. A connection 74 is provided for supplying the treating solution to 'the treating tower 7c tower 7d.

through the pump 18c and the connection 19, and a connection 75 is provided for supplying the treating solution to the treating The connect-ion 74 is arranged to withdraw fresh caustic alkali solution from either tanks 35" or 35c through connections 36b and 76, respectively, and to withdraw from the tank 32h either condensate mixture or separated used alkali solution through connection 33" or the separated oil component of the mixture through connection 46h. The connection 75 is similarly arranged to withdraw fresh caustic alkali solution from either tank 35b or 35 or 35d through connection 76 or 36C or 36d, respectively, and to withdraw from the tank 32 either condensate mixture or separated used alkali solution through connection 33 or the separated oil component of the mixture through connection 46".

In carrying out the process of the invention in the apparatus illustrated in Fig. 3, the vaporizing stills are charged with oil or distillate containing the lubricating oil fractions and are heated. T he vapors from each still enter the treating tower connected therewith and flow upwardl therethrough. In the apparatus illustrate fractionating towers are shown on the va orizing stills but these may be omitted anc the vapors from the still conducted directly to the treating tower. A series of progressively heavier charging stocks may be separately supplied to the several stills either throughv connections 15", 15c and 15d or through connections 11", 11C, and 11, the latter particularly where no fraitionating tower is employed; or a lubricating oil-containing charging stock may with advantage be supplied to the vaporizing still 5b, after vaporization of lighter components the heavier residual oil pumped to still 5, and after vaporization of another fraction in still 5 the heavier residual oil pumped to still 5d- In the several treating'towers the lubricating oil vapors are contacted in countercurrent flow with a caustic alkali solution supplied to the upper end of thetreating towers. In the first treating tower 7b this solution is fresh caustic alkali solution With-v drawn from the tank 35b In the second treating tower this solution may include used of the two. In 'the apparatus illustrated,

separate fresh alkali solution tanks are shown for each treating tower, but where only a single strength of treating solution is used only a single supply tank is necessary. More concentrated treating solutions may be used in the treatment of the heavier vapors; and, where the used alkali solution from the treatment of lighter vapors is employed in admixture vwith fresh alkali solutionin the successive treatment of heavier vapors, the concentration of the composite alkali solution may be adj usted by regulating the concentration of the fresh caustic solution admixed therewith. For example, water may be evaporated from the alkali solution in the treating tower and this more concentrated solution can be brought to the proper degree of concentration for `further use in a following treating tower by admixing a relatively dilute caustic alkali solution therewith. In successive treating towers, treating solutions similar 'to those used in the second may be employed.

In one particularly advantageous way of carrying out the invention, the oilcomponcnt of the condensate mixture separated in the treating towers may be introduced into a successive treating tower through which vapors heavier than those in the treating tower in which it is formed are passing. In A this mode of operation the treating tower operation is controlled to separate heavier constituents, those heavier than desired in the particular cut, from thc lubricating oil vapors passing therethrough, and these heavier constituents are introduced into a successive treating tower where heavier lubricating oil vapors are undergoing treatment. In the successive tower the introduced oil is employed to promote separation of heavier constituents from the vapors therein in :1 similar way and the introduced Oil is itself fractionated, the constituents corresponding to the desired cut being vaporized and escaping from the treating towers with the other vapors. The fractionation may thus be improved. This mode of operation is particularly advantageous where no fractionating tower is employed between the vaporizing still and the treating tower.

The oil component of the condensate mixture may thus be separated from the admixed used alkali solution and employed in admixture with fresh alkali solution for introduction into a successive treating tower, or the condensate mixture itself, including the used alkali, may be directly introduced into a successive treating tower, either alone or with the addition of fresh alkali. The oil component of the treating tower condensate mixture from the last still in the series may be subjected to further simple distillation, advantageously in the presence of an alkali, which alkali may be the used alkali component of the condensate mixture or fresh caustic alkali.

The process of the invention is of general application to lubricating oil-containing oils and distillates. It maybe applied to crude petroleums or to topped crude oils from which lighter constituents, such as gasoline, have been stripped. It is also applicable to the treatment of other oils and residues containing lubricating oil constituents, such as crude lu ricating oil distillates and fractions. It may be employed in the treatment of oils of either asphaltic or parafiine base or mixed base oils. Following the distillation and re- CII fining treatment of the present invention, the lubricating oil distillate fractions may be file tered through fullers earth or similar material or subjected to such other treatment as may be desired. Wax containing distillates, for example, may be subjected to suitable dewaxing operations in the usual'manner. In referring to lubricating oils herein, reference is made to the petroleum oils characterized by oiliness and high viscosity. In general these oils may be defined as oils made up of constituents heavier than gas oil, having a gravity lower than about B. and a viscosity upwards of about at 100 F. Saybolt universal.

I claim:

1. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from a body of oil containing lubricating oil constituents While injecting steam into the body of oil, separating lubricating oil vapors from heavier constituents of the vapors, subjecting the lubricating oil vapors to treatment with a caustic alkali solution and condensing the vapors from the alkali treatment to obtain a lubricating oil condensate.

2. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from a body of oil containing lubricating oil constituents under sub-atmospheric pressure, separating lubricating oil vapors from heavier`constituents of the vapors, subjecting the lubricating oil vapors to treatment with aV caustic alkali solution and condensing the vapors from the alkali treatment to obtain a lubricating oil condensate. y

3. An improved method of distillmg and refining lubricating oils, which comprises vaporizing lubricating oil constituents from a body of oil containing lubricating oil constituents under. sub-atmospheric pressure while injecting steam into the body of oil, separating lubricating oil vapors from heavier constituents of the vapors,y subjecting the lubricating oil vapors to treatment lwith a caustic alkali solution and condensing the vvapors from the alkali treatment to obtain a lubricating oil condensate.

4. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricatingloil constituents from a body of oil containing' lubricating oil constituents, subjecting the .lubricating oil vapors to treatment with a caustic alkali solution While undergoing condensation, cooling the condensate from the alkali treatment, and condensing the vapors from the alkali treatment to obtain a lubricating oil condensate.

5. An improved method of distilling and refining lubricating oils,"which comprises vaporizing lubricating oil constituents from a body ot oil containing lubricating oil constituents, subjecting -the lubricating oil vapors to treatment with a caustic alkali solution while undergoing condensation, condensing the vapors from the alkali treatment to obtain a lubricating oil condensate, and cooling the condensate from the alkali treatment and separating the cooled condensed oil lfrom `associated alkali.

6. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from a body of oil containing lubricating oil constituents, subjecting the lubricating oil vapors to treatment With a caustic alkali solution, subjecting the vapors from the/alkali treatment to a fractionating operation, and separately collecting a lubricating oil condens-ate and the uncondensed vapors therefrom, and condensing the vapors. Y

7. An im roved method of distilling and refining lu ricating oils, which comprises vaporizing` lubricating oil constituents from a body of oil containing lubricating oil constituents, subjecting the lubricating oil vapors to treatment with a caustic alkali solution, subjecting the vapors from the alkali treatment to a fractionating operation, and maintaining the vapors under a sub-atmospheric pressure throughout'the operation.

8. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from each of a plurality of bodies of oil containing lubricating oil constituents, subjecting the lubricating oil vapors from each body to treatment with a caustic alkali solution, and supplying condensate and associated alkali from treatment of lighter vapors to treatment of heavier vapors. y f

9. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from each of a series of progressively heavier bodies of oil containing lubricating oil constituents, subjecting the lubricating oil vapors from a lighter body to treatment with a caustic alkali solution, and subjecting the lubricating oil vapors froml a heavier body to treatment with condensate and associated alkali from the treatment of the vapors from the said lighter body.

10. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from a body of lighter oil containing lubricating oil constituents and subjecting the lubricating oil vapors therefrom totreatment with a caustic alkali solution, vaporizing lubricating oil constituents from a body of heavier oil containing lubricating oil constituents'and subjecting the lubricating oil vapors -I refining lubricating oils,

therefrom to treatment withy condensate and associated alkali from the first mentioned treatment.

11. An improved method of distilling and which comprises vaporizing the lubricatin oil constituents from a body of oil containing lubricating oil constituents, treating the lubricating oi vapors therefrom with a caustic alkali solution,

therefrom to a 10 transferringrunvaporized oil second body of oil, vaporizin further lubrieating oil constituents from t e second body 01E oil, treating the lubricating oil vapors from the second body with condensate and associatedialkali from the alkali treatment of the 15 lubricating oil va rs from the rst body.

In testimony w ereof I aliix m signature.

GEORGE H. TA ER, Jn.