US1756156A - Refining hydrocarbon oils - Google Patents

Description

April 29,1930. E. c. Vl-IER'rl-n-zl. ET AL 1,756,155

` REFINING HYDROCARBON OILS Filed June 16, 1928 ATTORN EYS Patented pr. 29, 1930 UNITED STATES PATENT ori-ica EUGENE C. HER'IHEL, 0F CHICAGO, ILLINOIS, AND HARRY L. PELZER, HIGHLAND, INDIANA, ASSIGNOBS T SINCLAIR REFINING COMPANY, OF NEW YORK, N. Y., A

coRPoRATIoN or MAINE Application led J'une 16,

f This invention relates to improvements inI the manufacture of distilled lubricating oils from petroleum stocks. The invention is of special value and application in the manufacture of distilled lubricating oils from cer- ,tain types of crude oils or crude oil stocks 35 B., and having viscosities upwards of about 50 at 100 F. Saybolt Universal.

There is a group of constituents, apparently characteristic of/naphthene base crude oils, which are extremely objectionable as components of lubricating oils in particular. These constituents are particularly objectionable in that they render unstable lubricating oils in which they are present. They also impair thev quality of lubricating oils .containing'them in other respects, color for example.

As yet, this group of objectionable constituents `has not been definitely identified. These objectionable constituents are themselves apparently of relatively low boiling oint, yet they polymerize quite readily to orm la tar or tarry substance. This polymerization is promoted, for example, by the presence of air or steam. With certain types of stocks, additional quantities of these objectionable constituents seem to be formed as long as the oil is maintained at elevated temperature, this effect increasing with temperature increase.

A number of schemes of procedure h ave been proposed intended to avoid the objectionable incidents of the presence of this group of objectionable constituents in lubricatino oils, but these proposals have not been entirely satisfactory; in some cases because of operating diiculties and in other cases because of failure to reach the real difficulty.

The present invention provides particularly an improved method of separating constituents of the objectionable group noted above from lubricating oil vproducts: `produced 'from stocks containing these objectionable constituemts, and lthe present invention is also useful in other applications, as will appear, in providing an improved method of treat- REFINING HYDROCABBON OILS 1928. Serial N0. 285,823.

ing llubricating oil products with caustic alkali. This invention in one aspect is an improvement upon the operation described in our application tiled June 16, 1928, Serial No.285,820. A

According to the present invention, the petroleum stock containing the lubricating oil constituents is subjected to distillation and during the distillation the vapors forming the lubricatin oil products when condensed are bubbled t rough a series of superposed hot' alkaline liquid oil baths of progressively increasing alkalinityand the escaping vapors after passage through the series of baths are condensed to form the distilled lubricating oil products. The constituents of the raw stock suitable as components of the desired lubricating oil products are vaporized therefronnthese vapors are bubbled through the series of hot alkaline liquid oil baths, the vaporsbeing introduced beneath the surface of each of the baths, the oil baths are maintained alkaline by supplying a caustic alkali to the treating bath through which the vapors last pass and overflowing the liquid from this bathto the preceding bath and soon, and vapors including the components of the desi-red lubricating oil products are taken off from the last hot oil bath. These vapors are condensed without permitting the resulting condensate or condensates to contact with the liquid flowing countercurrent to the vapors through the series of hot oil baths. In the series of hot alkaline liquid oil baths, the lubricating oil constituents are repeatedly subjected to intimate contact with caustic a1- kali in generally countercurrent low. The caustic alkali neutralizes acidic constituents of the oil vapors and, apparently, also acts as a polymerizing agent promoting the polymerization of constituents of the objectionable group noted above. Steam may with' advantage be supplied to the treating operation as a distillation medium, and when soA supplied also assists 'in this polymerization andy in some cases seems to make the caustic alkali more active.v The highboiling constituents not suitable as components of the lubricating oil products including reaction products of the hot alkaline' treatment and the products of polymerization of any objectionable constituents present are condensed and, flowing downwardly through the treating baths, are discharged from the lowermost. l

The vaporization of the raw petroleum stock may be effected in a shell still or a pipe still, for example The vaporization may be carried out under pressures approximating .atmospheric pressure or under subatmospheric pressure and with or without the introduction of steam or other'hot gaseous medium reducing the partial pressure of the oil vapors. As applied to crude oils, the vapors subjected to the alkaline treatment of the invention may comprise the total vaporized fraction of the crude oil.

'The alkaline treatment of the invention .is advantageously carried out` in a so-called bubble tower modified to maintain down- :flow therethrough of the oil-alkali mixture or suspension forming the liquid of the several treating baths. rlhe caustic alkali is advantageously supplied to the treatment as a concentrated aqueous solution; the water is evaporated in the treating baths leaving the alkali suspended in the oil forming the baths.. The vapors taken od from the last treating bath ma with advantage be subjectedvto a reluxing operation from which separated material is returned to this bath before the vapors are subjected to condensing operat-ions for the condensation of the lubricating oil roducts. Entrainment of constituents o the hot oil baths may thus be avoided. The vapors taken off from the alkaline treatment may be condensed or fractionally condensed in any convenient apparatus. These vapors may, for example, be

passed through a series of towers in whichl progressively lighter fractions are condensed. As applied to crude oils, the vapors taken olf from the neutralization and separation treatment may thus be condensed as a series of distillates, the heavier and more. viscous fractions of the series constituting the lubricating oil products. i

The invention will be further described connection with the accompanying drawing which illustrates,` diagrammatically and conventionally, one form of apparatus adapted, in conjunction with a suitable still and a suitable fractionating or condensing system for. carrying out-the invention. It will be understood that the invention can be carried -out in other and different forms of apparatus; this particular form is illustrated, merely for purposes of exemplification. Any usual form of still and any usual fractionating or condensing system may be used in carrying out the invention and this part of the apparatus is, therefore, not illustrated.-

. In the drawing, Fig. 1 is an elevation of a complete treating tower and Fig. 2 is an enlarged fragmentary section of the same.

maare@ Referring to the drawing, in the apparatus illustrated the vapors from the still are supplied through line 1 and are takin off, following the treatment of the inventlon,

through line 2 to the fractionating or contower. Line 8 is provided for discharge of liquid from the lower end` of the tower.

Lines 10, :11' and 12 are provided for supplying caustic alkali to one or more'of the upper plates in the tower as desired. rlhe tower 3, and the vapor connections between this tower and the still, is with advantage lagged or thermally insulated. The temperature conditions in the tower 3 are controlled by regulating the temperature of the vapors entering through line 1, the circulation of a cooling medium through either or both of the coils 4 and 5 and the introduction of steam or other heating medium through line 9. Oil to be supplied to the still may be used as a cooling medium or some suitable external cooling medium may be so used.

The several plates 13, 14, 15, 16, 17 and 18 in the middle section of the tower 3 comprise bubble caps 6 adapted to compel the vapors flowing upwardly through the tower to bubble through the liquid on the plates and overiiow connections 7. Each overflow connection extends upwardly through the plate to which it is connected to a height appropriate to form a seal maintaining a liquid level submerging the lower edges of the bubble caps on the plate. An annular baflie 19 is arranged around the upper end i. f

of this extension so that the li uid flowing downwardly through the `over ow conncca tion is discharged from the bottom of the liquid bath on the plate instead of from the y top as in the usualconstruction.

In carrying out' the invention in the apparatus illust-rated, the ylubricating .oil vapors supplied through line 1 are bubbled successively through the hot liquid oil bath on plate 13, then through that on plate 14, and so on,v through the tower, caustic alkali is supplied to the bath on plate 10, 11, or 12, the bath liquid is overflowed from the ,plateV to which the caustic alkali is supplied to the next lower plate and so on through the tower, the caustic bottoms are discharged `through connection 8, and the lubricating oil vapors after passage through the series of hot alkaline liquid oil bathsk are taken off through yline 2 and separately condensed. The temperature at the lower end of the tower is controlled to maintainfin vapor phase all oil constituents suitable as cornponents of the desired lubricating oil products and the temperature at the upper end vof the' tower is controlled to condense tarry `or alkaline or other'heavy constituents not hour and discharged from the pi e still at a temperature of about 800 F. A er separation Aof unvaporized residual oil, the vaporized part of the stock is supplied through line 1 to the lower end of tower 3. An aque- -objectionable constituents. Improved tionation in the treating operation is also ob- 'ous solution of caustic soda, 25 B., is supplied through line 11 to the next to the top plate in the tower 3 at a rate slightly exceeding 4 gallons per hour. The temperature at the top of tower 3 is maintained in the neighborhood of G-690 F. and the temperature at the bottom of the tower vin the neighborhood of (i90-710 F. Steam superheated to SOO-900 F. is supplied through line 9 and a coolin medium is circulated through coil 4 or coil 5 or both coils las required to maintain these temperatures. The vapors escaping through line 2 from the upper end of tower 3 are `fractional'ly condensed `to form a hea lubricating oil, va light lubricating oil aniriya composite gas oil and naphtha.

Again referring to the drawing, in the apparatus illustrated, the caustic alkali may be supplied to Ieither plate 16, plate 17 or plate 18. By supplying the caustic alkali to one 'of the lower plates, 16 or 17 the vapors escaping from the bath on the plate to which the caustic alkali is supplied, the last of the treating baths, are subjected to a reluxing operation on the remaining plate or lates.

he operation of the invention provides for prolonged intimate contact between the lubricatinv oil vapors and the hot alkaline treating liquid with a low pressure drop through the treating operation. In this aspect the invention is particularly advantageous because it avoids deterioration' of lubricating oil constituents at the same time that it promotes the eiectiveness of the rening treatment, this dfliculty being peculiar to lubricating oils because of `their relatively high boiling point -at any particular pressure and because of their tendency toward decomposition at elevated temperatures. The countercurrent aplication of the caustic alkali makes the a1- ali more eiective and makes it unnecessar to. use more than avsmall excess of the alka i to effect substantially complete separati? of tained in carrying out theinvention. This `products with high-boilin oil-soluble reaction products of the alkaline treatment.

The invention is particularly adapted to continuous operation, and the control afforded by the invention is of special value in maintaining uniform the distillate products. over long periods of operation.

We claim:

1. In the distillation of petroleum stocks for the production of lubricating oils, the improvement whichv comprises vaporizingv from the stock those constituents suitable as com onents of the desired lubricating oil, passing the vapors containing these constituents successively through a series of hot alkaline liquid oil baths by introduction beneathy the surface thereof, supplying-caustic alkali to a bath other than the first in the series,' passing liquid from this bath to the preceding bath and so on through the series in countercurrent to the vapors, dischargin liquid from the first bath in the series, ta ing olf from'the last bath in the series the components of the lubricating oil in the'vapor state and condensing the same without lpermitting this condensate to contact as suc with the liquid forming the oil baths.

2. vIn the distillation of petroleum stocks for the production of lubricating oils, the improvement which comprises vaporizing from the stock those constituents suitable as component's of the desired lubricating'oil, passing the vapors containing these constituents successivel through a series of hot alkaline liquid oil aths by introduction beneath the surface thereof, supplying caustic alkali to a bath other than the first in the series, passing liquidfrom the lower part of the baths our names..v

. EUGENE C. HERTHEL.;

HARRY' L. PELZER.

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