US1777307A - Art of cracking hydrocarbons - Google Patents

Description

@at 7, 1930., E. c. HERTHEL E1' AL' ART OF CRACKING HYDROCARBONS Filed June 4, 1929 rameau oa, v, aan

aus ci manana, on rana, assreivoas ro @narran er raar-aa MT OF CEAGKING HYD cannons Application tiled June t, 1839A. Serial No; 368,229.

This invention relates to improvements in the manufacture otvdistilled lubricatihg oil from raw lubricating oil containing stocks including raw crude stocks such( as crude pet troleums and reduced crude petroleums and distillate 'fractions containing lubricating oil components.

This inventionv provides an improved method of distilling reined, or partially re# El@ ned, lubricating oils from raw stocks containing lubricating oil components. In the improved method of the invention, vaporization of the lubricating oil fraction from the raw lubricating oil containing stock is E@ edected by direct heat exchange between this ravv stock and the hot vapor products from a vapor hase cracking operation following regulation ot the temperature of these hot vapor products to avoid decomposition of lubricating oil constituents,1 Ubjectionable decomposition of lubricating oil constituents is thus. minimized; decomposition due to local overheating is avoided by the direct heat exchange, general overheating is avoided by regulation or the temperature of the hot vapor products from the vapor phase cracking operation, and the partial pressure of these hot vapor products is utilized to reduce the artial pressure ot the vaporized lubricat- 8@ ing oil constituents. Also, in the improved method of the invention, the raw lubricating oil lcontaining stock is supplied to the operation as a mixture including a caustic alkali,

such as quick lime 'or caustic soda, so that the lubricatingv oil constituents vaporized from this raw stock are maintained within the zone ot activity oi the caustic alkali until vapor- Aized and consequently throughout the entire temperature range over which these constitut@ ents are heated up to the maximum temperature of this range. rlhe vaporized lubricating oil constituents are condensed from the resulting vapor mixture including vthese constituents as Well as vapors from the vapor ,ZY-'i5 phase cracking operation, by a suitable fractionating operation, and components of thel then remaining vapor mixture higher boilin than suitable as "com onents of the desire low boiling product o the vapor phase crack` uxing operation, and supplied to the vapor phase cracking operation. This reflux con densate so supplied ,to the vapor phasecrack-1 ing operation may include constituents of the raw lubricating oil containing stock supplied to the operation lower boiling than suitable as.

` ation and the vapor mixture from this vapor ,naar

phase cracking operation is subjected to a scrubbing operation for the separation of tare The oil supplied to the vapor phase craclng operation may comprise the reflux condensate previously mentioned or a mixture of such condensate and raw oil. Regulation of the temperature of the hot vapor products from the vapor phase cracking operation and the direct heat exchange between these hot yvapor products and the raw lubricatin oil containing stock is elected in this scrub ing o eration. Regulation of the temperature o the hot vapor products from the vapor phase cracking operation is advantageously eiected by introducing the hot oil productsfrom thisoperation into the scrubbing operation into and beneath the surface of a liquid body of oil therein and regulating the scrubhing operation to maintain this liquid body at the'- desired temperature, The raw lubri cati'n oil containing stock is mixed with caustic alkali and this mixture is introduced into the vapors in the scrubbing operation and the lubricating oil components ot this raw stock mixture are vapor-ized therein by heat exchange With these vapors. 'll-he resulting vapor mixture is then lsub]ected, successively, to the fractionating operation and the re'iuxing operation'v previously mentioned. The .lubricating oil product is discharged from thefractionating operation 'Without being permitted to return to thevapor phasecracking operation. 'llhe tar sep arated in the scrubbing operation, including tar components from the vapor mixture from the vapor phase cracking operation and 'any residual components from the raw lubricatingoil containing stock and any unconsumed causticalkali and the solid or semi-solid reaction products of the caustic alkali, is discharged without being permitted to return to the vapor phase cracking operation.

The inventlon will be further described in connection with the accompanying drawings which illustrate, diagrammaticaily and conventionally, in elevation and partly in sec.- tion and with parts broken away, one form of apparatus adapted for carrying out the process of the invention. The particular apparatus shown is shown merely for purposes of illustration.

The apparatus illustrated includes a vapor phase cracking apparatus described in more detail in an application tiled June 13, 1927, Serial No. 198,621.

Referring to the drawings, the oil suplied to the vapor phase cracking operation 1s supplied to the heating conduit 1 through connection 2. is heated and vaporized and the vapors superheated in the heating conduit, the vapors are passed to the digesting drums 4 through connection 5 and from the last digesting drum are discharged into the lower end of the scrubbing tower 6 through connection 7 For example, the temperature of the vapors passing from the heating conduit 1 to the digesting drums 4 may approximate 1050-1150o F., the temperature of the vapors passing from the digesting drums 4 to the scrubbing tower 6 may approximate 900-1100o F., the oil may be supplied to the heating conduit 1 under pressure just sufficient to force theoil and oil vapors throu h the apparatus, and the pressure in the scru bing tower 6 may approximate 2,45 ot mercury.

The vapors discharged into the scrubbin tower 6 through connection 7 are discharged into and beneath the surface of a liquid body of oil maintained in the lowerend of the scrubbing tower during normal operation. As the vapors pass through` this liquid body of oil, entrained tar components, or most oi;

them, are separated and the temperature oi the vapors is reduced, for example, to a temperature in the neighborhood of 750-800 F. or lower. .The raw lubricatingoil con-` taining stock is mixed with fromr 3/2 to 3 pounds er barrel, for example, of quick lime or caustlc soda and this mixture is introduced into the upper end of the scrubbing tower 6 Pthrough connection 3. In the scrubbing tower, the lubricating oil components of this mixture are vaporized by direct heat exchange with the vapors from the vapor phase cracking operation, any residual components of this mixture and any unconsumed caustic alkali and the solid or semi-solid reaction products of the caustic alkali collect in the liquid body of oil maintained in the lower end of the tower together with the tar components separated from the vapors from the vapor phase cracking operation. This tar or tar mixture is discharged from the lower end of the scrubbing tower 6 through connection 13 without being permitted to return to the vapor phase cracking operation. The operation carried out in the scrubbing tower 6 may be controlled, or in part controlled, by regulation or' the rate at which the raw lubricating oil containing'stock-caustic alkali mixture is introduced lthrough connection 3. This control may be supplemented by the regulated reintroduction of part of the tar discharged through connection 13 through connection 9 while hot by means of pump 10 or after cooling in cooler 11 by means of pump 12. For example, the temperature of the liquid body maintained in the lower end of tower 6 may Yapproximate 7 25-775 F. and the'lteniperature of the vapor mixture escaping from the upper end of the tower 6 may approximate 67 5,-725o F.

The tar discharged through connections 13 and 8 may, for example, be subjected to coks ing distillation to separate oil components from/alkali or alkali reaction products.

The vapor mixture escaping from the upper end of the scrubbing tower 6 through connection 15 is discharged into the lower end of fractionating tower 22 through connection 23. This vapory mixture includes the vaporized components of the raw lubricating oil containing stock introduced into the scrubbing tower 6 and the uncondensed components of the vapor mixture discharged from the vapor phase cracking operation into scrubbing tower 6. The vaporized lubricating oil components of this vapor mixture are condensed in the ractionating tower 22 and the resulting lubricating oil condensate isl discharged from the lower end otfractionating tower 22 through connection 24. The operation of this ractionating tower may be controlled by regulated circulation of a cooling'medium, water for example, through a cooling coil 25 arranged in the upper end of the tower. For example, the temperature of the vapor mixture escaping from the upper end of the tower 22 may approximate 50G-57 5 F. l

The vapor mixture escaping from the upper end of fractionating tower 22 through connection 26 is discharged into the lower end of reflux tower 14 through connection 16. In this tower, vapors higher boiling than suitable as components of the desired low boiling product of the vapor phase cracking operation but lower boiling than suitable as components of the lubricating oil condensate separated in tower 22 are condensed from this vapor mixture. The operation of this tower/.may be controlled by the regu-1 lated introduction, through connection 17',`

of raw oil to be supplied to the vapor phase cracking operation or of a. fraction corresponding in character to the desired low boiling product. For example, the temperature of the vapor mixture escaping from the upper end of the' tower 14 may approximate S75-425 F. The condensate or condensate mixture from the reiux tower '14 is supplied to the heating conduit 1 of the vapor phase cracking apparatus through connections 19 and 2 by means of hot oil pump 18. This condensate stock may include components vaporized from the raw lubricating oil containing stock introduced into the scrubbing tower 6. F or example, a reduced crude oil including gas oil components and lubricating oil components may be introduced into the scrubbing tower 6, the lubricating oil components separated in the fractionating tower 22 and the gas oil components separated in reiiux tower 14 and supplied therefrom to the vapor phase cracking operation as fresh stock. Fresh stock may also be supplied to the vaporphase cracking operation through connection 20.

The vapor mixture escaping from the upper end of reiiux tower 14 through connection 21 includes the desired low boiling product of the vapor phase cracking operation, gasoline for example. This vapor mixture is with advantage discharged through connection 21 directly to a condenser. It may, however, be subjected to further fractionating operations or refining operations.

Thescrubbing tower 6, the fractionating tower 22 and the reliux tower 14 are with advantage of construction adapted to involve a minimum pressure drop therethrough in operation. The scrubbing tower 6 is with advantage lagged or thermally insulated. The fractionating tower 22 and the reiux tower 14 are with advantage lagged or thermally insulated where, as in the apparatus illustrated, condensation therein is effected' by internal cooling.

We claim:

In the manufacture of lubricating oils, the improvement which comprises subjecting oil to a vapor phase cracking operation and subjecting the vapor mixture from the said vapor phase cracking operation to a scrubbing operation for the separation of tar, mixing caustic alkali with the raw lubricating oilcontaining stock and introducing this caustic alkali-lubricating oil stock mixture into the vapors in the said scrubbin operation and thereby vaporizing the lubricating oil components of the raw lubricating oil-'containing stock in the scrubbing operation, subjecting the resulting vapor mixture escaping from the said scrubbing operation including the uncondensed components of the vapor mixture from the vapor phase cracking operation and the vaporized components of the lubricating oil stock introduced into the scrubbing operation successively to a fractionating operation and to a reiluxing operation, condensing the vaporized lubricating oil components from the vapor mixture in the said ractionating operation and discharging this lubricating oil condensate from the said Jractionating operation without permitting this discharged lubricating oil condensate to return to the said vapor phase cracking operation, condensing in the said reluxing operation vapors higher boiling than suitable as components of the desired low boiling product of the said vapor phase cracking operation and lower boiling than suitable as components of the lubricating oil condensate condensed in the said fractionating operation and supplying this reflux condensate from the said refluxing operation to the said vapor phase cracking operation, and discharging tar including tar components separated from the vapor mixture from the said vapor phase cracking operation and any residual components separated from the raw lubricating oil-containing stock introduced into the scrubbing operation and including any unconsumed caustic alkali and the solid or semisolid reaction products of the caustic alkali from the said scrubbing operation without permitting this discharged tar to return to the said vapor phase cracking operation.

In testimony whereof we a'x our signatures.

EUGENE C. HERTHEL. HARRY L. PELZER.

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