US2079148A - Conversion of hydrocarbon oils - Google Patents

Description

May 4, 1937. I J. B. BARNES I 2,079,148

v CONVERSION OF HYDROCARBON OILS Filed Sept. ,28, 1952 FRACTIONATOR FURNACE INVENTOR JOHN B. BARNES AT TO Y Patented May 4, 1937 UNITED STATES 2,079,148 CONVERSION OF HYDROCARBON OILS John B. Barnes, Chicago, 111.,

assignor to Universal Oil Products Company, Chicago, 111., a. corporation of Delaware Application. September 23, 1932,. Serial No. 635,187

3 Claims.

This invention particularly refers to an improved process and apparatus for the conversion of hydrocarbon oils wherein raw oil charging stock for the system is subjected to less severe conversion conditions than the reflux condensate (insufliciently converted intermediate products which are returned to further conversion in the same system) while vaporous products resulting from the relatively mild conversion of the charging stock are subjected to continued conversion time at'an elevated temperature, together with the more highly heated reflux condensate.

It is well known that hydrocarbon oils of a relatively heavy nature such asheavy gas oil, fuel oil, residual oil, heavy crude oils and the like yield excessive quantities of undesirable heavy conversion products such as coke and pitch-like residue when subjected to the conversion conditions most suitable for. the treatment of their low boiling fractions.

In the present invention provision is made for subjecting the raw oil charging stock to relatively mild conversion conditions such as will not affect the production of excessive yields of coke and other undesirable heavy residual products, from its high boiling components, at the same time providing for further conversion of the insufliciently converted intermediate products of the process under the more severe conditions essential to the production therefrom of maximum yields of motor fuel of high anti-knock quality and the invention further provides for subjection of the vaporous conversion products resulting from said relatively mild treatment of the charging stock to further conversion by commingling them with the more highly heated reflux condensate "and subjecting the mixture to continued conversion time.

A more specific embodiment of the present invention may comprise subjecting raw oil charging stock to relatively mild conversion conditions of elevated temperature, superatmospheric pressureand conversion time in a heating coil and communicating enlarged reaction chamber, separating the vaporous and residual light conversion products insaid reaction chamber, simultaneously subjecting insufiiciently converted intermediate products of the process to more severeconversion conditions of elevated temperature, superatmospheric pressure and conversion time, in a separate heating coil and communicating enlarged reaction chamber, withdrawing vaporous conversion products from the first mentioned reaction chamber and commingling them with the more highly heated products in said separate reaction chamber whereby they are subjected to continued conversion time in this zone at an increased temperature over that at which they are withdrawn in the first mentioned reaction chamber, subjecting residual liquid conversion products from both re- 5 action chambers to further vaporization at substantially reduced pressure, subjecting vaporous conversion products from both the cracking and the residuum vaporizing operations to fractionation whereby their low boiling components of the desired characteristics are separated from their higher boiling insufiiciently converted components, which latter are condensed as reflux condensate to form the material supplied to said separate heating coil.

One specific form of apparatus embodying the features of the present invention is illustrated in the accompanying diagrammatic drawing, the following description of which will serve to more clearly illustrate the advantages and features of the present invention.

Raw oil charging stock for the process is supplied through line I and valve 2 to pump 3 from which it is fed through line 4 and valve 5 into heating coil 6. Although not illustrated in the drawing, it will be understood that the raw oil may, when desired, be preheated in any well known manner, prior to its introduction into the heating coil.

Furnace l, enclosing heating coil 6, serves as a means of heating the oil passing through the heating coil to the desired relatively mild conversion temperature, preferably at a substantial superatmospheric pressure, and the heated oil is discharged through line B and valve 9 into reaction chamber ill. i

Chamber H1 is also preferably maintained at a substantial superatmospheric pressure and, although not, illustrated in the drawing, is preferably well insulated to prevent the excessive loss of heat by radiation. In this manner, the heated conversion products from heating coil 6, and particularly their vaporous components, are subjected to continued conversion during their downward passage through chamber [0. Vaporous and residualliquid conversion products are separated in chamber In, the residual liquid being withdrawn from the lower portion of the chamber through line H and valve 12 while the vaporous conversion products are withdrawn from a somewhat higher point in the lower portion of the chamber through line [3 and valve l4 and discharged into reaction chamber l5.

Chamber l5, like chamber Ill, is preferably maintained at a substantial superatmospheric Y completed. Preferably,

pressure and is well insulated to prevent the excessive loss of heat by radiation. Vaporous conversion products from chamber ID are commingled in chamber l5 with more highly heated intermediate conversion products of the process supplied to this zone, as will be later more fully described. The commingled conversion products, and more particularly their vaporous components, are subjected to continued conversion time as they pass downward through chamber l5. Vaporous and residual liquid conversion products may be again separated in chamber IS, the residual liquid being withdrawn from the lower portion of the chamber through line It and valve into line H, commingling therein with the residual liquid from chamber l6 and passing therewith to vaporizing chamber l8. Vaporous conversion products of the cracking operation may be withdrawn from a somewhat higher point in the lower portion of chamber l5 through line I9 and valve to fractionation in fractionator 2| or, when desired, the vaporous products from chamber |5 instead of passing directly to fractionator 2| may be introduced into chamber l8 either by supplying them to this zone through a separate line, not illustrated in the drawing, or by withdrawing them from chamber i5, together with the residual liquid, through line It and valve I! to pass therefrom through line H, together with residual liquid from chamber l0 into chamber I8. vaporous products, when withdrawn from chamber l5 together with the residual liquid, or when separately introduced into chamber l8 below the level of residual material in this zone, may serve as a means of assisting vaporization of the residual oil supplied to chamber l8, thereby regulating the quality of the final residual product of the system. It will be understood that the vaporous products from chamber I5 may be handled in any one or any combination of the manners described, so that all or only a portion, or none of the vaporous products may be utilized,

as desired, to assist vaporization of the residue in chamber I8. U

Chamber I8 is preferably maintained at a substantially reduced pressure relative to that employed in the reaction chamber, by means of which further vaporization of the residual oils supplied to this zone from the reaction chambers is effected. By regulation of the operating conditions employed, the quality of the residual product of the process which collects in chamber l8 may be varied from a good quality residual liquid suitable for use as fuel oil through the various stages of asphaltic and pitohy materials to substantially dry petroleum coke. When a liquid s recovered as a residual product of the process it may be withdrawn from chamber |8 through line 22 and valve 23 to cooling and storage or to any desired further treatment. When a solid or semisolid such as coke or asphaltic material is produced it may be allowed to accumulate in chamber l8, to be removed therefrom after the chamber has become substantially filled and its operation in the latter case, a plurality of chambers similar to chamber l8, but not illustrated in the drawing, is employed to provide additional space for the deposition of the residual product and they may be simultaneously operated or, preferably, are alternately operated, cleaned and prepared for further operation in order that the duration of the operating cycle of the process will not be limited by the capacity of this zone.

Vaporous products from chamber |8 are withdrawn through line 24 and valve 25 to line I9,

commingling therein with any vaporous products withdrawn through this line from chamber |5 as previously described, and passing therewith to fractionator 2|. Fractionated vapors of the desired end boiling point are withdrawn, together with uncondensable gas produced by the process, from the upper portion of fractionator 2| through line 26 and valve 21, are subjected to condensation and cooling in condenser 28 from which the resulting distillate and gas passes through line 29 and valve 30 to be collected in receiver 3|. Uncondensable gas may be released from the receiver through line 32 and valve 33. Distillate may be withdrawn from the receiver through line 34 and valve 35 to storage or to any desired further treatment. When desired, although not illustrated in the drawing, a portion of the distillate from receiver 3| may be recirculated, by well known means, to the upper portion of fractionator 2| to assist fractionation of the vapors and to maintain the desired vapor outlet temperature from this zone.

Components of the vapors supplied to fractionator 2|, boiling above the desired end boiling point of the final light distillate product of the process and comprising the insufficiently converted intermediate products of the operation, are condensed as reflux condensate in fractionator 2|, collecting within the lower portion of this zone, to be withdrawn therefrom through line 36 and valve 31 to pump 38, by means of which they are supplied through line 39 and valve 4|] to heating coil 4|. In passing through heating coil 4i, the reflux condensate from fractionator 25 is heated, by means of heat supplied from a furnace 42 of any suitable form, to a more severe conversion temperature than that employed in heating coil 6, preferably at a substantial superatmospheric pressure, and the highly heated reflux condensate is discharged from heating coil 4| through line 43 and valve 44 into reaction chamber IE to commingle therein with the vaporous conversion products from chamber ID, as already described, and being subjected therewith to continued conversion time and the subsequent treatment already described.

In a system such as illustrated and above described, the raw oil charging stock is preferably heated to a conversion temperature of the order of 850 to 950 F., with a superatmospheric pressure, measured at the outlet from the heating coil to which the raw oil is supplied, within the range of 100 to 500 pounds, or more, per square inch. Any desired pressure within substantially this same range but no greater than that employed at the outlet from the heating coil may be utilized in the succeeding reaction chamber and preferably is substantially equalized in the reaction chamber to which the vaporous products from conversion of the raw oil and the more highly heated reflux condensate are supplied. The reflux condensate is preferably subjected in the heating coil to which it is supplied to a temperature, measured at the outlet therefrom, within the range of 900 to 1050 F., preferably with a superatmospheric pressure, measured at this point, of from 300 to 800 pounds, or more, per square inch. The vaporizing or coking chamber, as already indicated, is preferably operated at a substantially reduced pressure relative to that employed in the reaction chambers which may range, for example, from 100 pounds or thereabouts, per square inch down to substantially atmospheric pressure. Pressures employed in the fractionating, condensing and collecting portions of the system may be substantially equalized with or somewhat reduced relative to the pressure employed in the vaporizing or coking chamber.

As a specific example of an operation of the process of the present invention, as it may be practiced in an apparatus such as illustrated and above described, the charging stock, comprising a 26 A. P. I. gravity Mid-Continent fuel oil, is subjected to a conversion temperature of approximately 910 F., at a superatmospheric pressure of about 350 pounds per square inch at the outlet from the heating coil to which it is supplied and substantially this same pressure is maintained in both reaction chambers of the system. The reflux condensate is separately subjected to a temperature of about 970 F'., at a superatmospheric pressure of about 400 pounds per square inch. The vaporizing chamber is operated at a reduced pressure of about 50, pounds per square inch, and this pressure is substantially equalized in the succeeding fractionating, condensing and collecting portions of the system. This operation may yield, per barrel of charging stock, about 55% of motor fuel having an anti-knock value equivalent to an octane number of approximately 76 and in addition may yield a good quality residual oil containing less than one-tenth of 1% B. S., and suspended carbonaceous material and amounting to about 35% of the raw oil charging stock, the remaining 10% or thereabouts, based on the charging stock, is chargeable to uncondensable gas, loss and a negligible amount of coke.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises passing the charging oil in a restricted stream through a heating zone and thence discharging the same into an enlarged reaction zone, subjecting the oil to cracking conditions of temperature and pressure in said zones, separating the oil into vapors and unvaporized oil in the reaction zone, introducing such separated vapors into a second reaction zone maintained under cracking temperature and pressure, simultaneously heating a stream of reflux condensate,

' formed as hereinafter set forth, in a second heating zone to higher cracking temperature than the charging oil in the first-mentioned heating zone, passing the thus heated condensate directly from the second heating zone into said second reaction zone to elevate the temperature of the vapors intrcduced thereto, subjecting the commingled hydrocarbons to continued cracking in the second reaction zone, then removing the commingled hydrocarbons from the second reaction zone and introducing the same to a reduced pressure, separating zone wherein vapors are separated from residue, removing the vapors from the separating zone and fractionating the same to condense heavier fractions thereof, supplying such condensed heavier fractions to the second heating zone as said reflux condensate, and finally condensing the fractionated vapors.

2. A hydrocarbon oil cracking process which comprises passing the charging oil in a restricted stream through a heating zone and thence discharging the same into an enlarged reaction zone, subjecting the oil to cracking conditions of temperature and pressure in said zones, separating the oil into vapors and unvaporized oil in the reaction zone, introducing such separated vapors into a second reaction zone maintained at cracking temperature and pressure; simultaneously heating a stream of reflux condensate, formed as hereinafter set forth, in a second heating'zone to higher cracking temperature than the charging oil in the first-mentioned heating zone, passing the thus heated condensate directly from the second heating zone into said second reaction zone to elevate the temperature of the vapors in troduced thereto, subjecting the commingled hydrocarbons to continued cracking in the second reaction zone,, then removing the commingled hydrocarbons from the second reaction zone and introducing the same to a reduced pressure separating zone wherein vapors are separated from residue, removing the unvaporized oil from the first-mentioned reaction zone and introducing the same to the reduced pressure separating zone for flash distillation thereof, removing the vapors from the separating zone and fractionating the same to condense heavier fractions thereof, supplying such condensed heavier fractions to the second heating zone as said reflux condensate, and finally condensing the fractionated vapors.

3. A hydrocarbon oil cracking process which comprises passing hydrocarbon oil in a restricted stream through a heating zone and thence discharging the same into an enlarged reaction zone, subjecting the oil to cracking conditions of temperature and pressure in said zones, separating the oil into vapors and unvaporized oil in the reaction zone, introducing such separated vapors, into a second reaction zone maintained at cracking temperature and pressure, simultaneously heating a stream of lighter oil in a second heating zone to higher cracking temperature than the oil in the first-mentioned heating zone, passing the thus heated lighter oil directly from the second heating zone into said second reaction zone to elevate the temperature of the vapors introduced thereto, subjecting the commingled hydrocarbons to continued cracking in the second reaction zone, then removing the commingled hydrocarbons from the second reaction zone and introducing the same to a reduced pressure separating zone wherein vapors are separated from residue, removing the unvaporized'oil from the first-mentioned reaction zone and introducing the same to the reduced pressure separating zone for flash distillation thereof, removing the vapors from the separating zone and fractionating the same to condense heavier fractions thereof, and finally condensing the fractionated vapors.

JOHN B. BARNES.

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