US1960598A - Conversion and coking of hydrocarbon oils - Google Patents

Description

y 1934- J. D. SEGUY I 1,960,598

CONVERSION AND COKING OF HYDROCARBONOILS Filed Aug. 29, 1952 Condenser Furzrace 16 fecal fir (bnden ser Furnace 66 fiffarze ep Patented May 29, 1934 i'i'so STATES CONVERSION AND come on HYDROCARBON OILS Jean Delattre Sesuy, Chicago, IlL, assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application 'August 29, 1932, Serial No. 630,856

4 Claims.

This invention relates to the conversion and coking of hydrocarbon oils and more particularly refers to an improved process and apparatus for,

the conversion of relatively heavy oils accompanied by reduction of the residual oil resulting from cracking to coke at reduced pressure relative to that at which the residual oil is formed.

More specifically, the invention involves a novel method of assisting the coking operation and effecting substantial devolatilization of the coke which comprises subjecting vapors from the coking operation to fractionation, subjecting a portion of the relatively light vapors and gases resulting from fractionation to further heating at a higher temperature than that to which the charging stock suppliedto the process is subed to condensation and a portion of the resulting distillate may be utilized alone as the heat carrying medium for the coking operation, being at the same time subjected to conditions during such retreatment which will efiect its conversion, or reforming. As a further feature of the present invention, that portion of the vapors from the coking which are condensed by fractionation and thus separated from the lighter components of the vapors, is returned to the stream of heated 4Q hydrocarbon oil, passing from the heating element to the reaction chamber of the cracking system, serving to partially cool said heated oil and being itself subjected to conversion by direct contact with the heated oil. Q

In one of its more specific embodiments the invention comprises subjecting a hydrocarbon oil into conversion conditions in a heating element and reaction chamber maintained at superatmospheric pressure, subjecting vapors from the reaction chamber to fractionation, condensing and collecting their desirable light components and returning their heavy components, which are condensed by fractionation, to the heating element for further conversion, removing residual liquid products from the reaction chamber and tion, into the stream of heated oil passing from 00 the'heating element to the reaction chamber, removing light vapors and gases from the last mentioned fractionator, subjecting a portion thereof to condensation and collecting the resulting distillate and gas, heating the remainder in a separate heating element to a higher temperature than that employed in the first mentioned heating element and introducing the highly heated material into thecoking zone where it comes into direct contact with the residual oil from the reaction chamber, assisting its coking and efiecting substantial devolatilization of the coke.

} One specific form of apparatus suitable for the practice of the present invention is illustrated in the attached diagrammatic drawing.

Raw oil charging stock for the system may be supplied through line 1 and valve 2 to pump 3 from which it is fed through line 4, valve 5 and line 6 into heating element 7. It will be understood that the raw oil may be preheated, when desired, by any well known means such as indirect contact with the hot vaporous or liquid prodacts of the system or by direct contact with the vaporousproducts undergoing fractionation, although such means are not here illustrated.

Heating element 7 is located in furnace 8 of any suitable form and the oil supplied thereto is heated to the desired conversion temperature and thence discharged through line 9, valve 10 and line 11 into reaction chamber 12. The heating element and reaction chamber are both preferably maintained at substantial superatmospheric pressure which may be substantially equalized between these two zones or may be somewhat reduced in the reaction chamber,

Vapors from the reaction chamber pass through line 13 and valve 14 to fractionation in fractionator 15 whereby their relatively heavy components are condensed, being withdrawn from the-lower portion of the fractionator through line 16 and 10o valve 17 to pump 18 from'which they are returned through line 6 and valve 19 to heating element 7 for further conversiontogether with the raw oil charging stock.

The relatively light desirable components of the vaporous cracked products are withdrawn, together with gas from the upper portion of the fractionator, through line 20 and valve 21 are subjected to condensation and cooling in condenser 22, distillate and uncondensable gas from which up passes through line 23 and valve 24 to be collected in receiver 25. Uncondensable gas may be re-- leased from the receiver through line 26 and valve 27. Distillate is withdrawn through line 28 and valve 29. A portion of the distillate may, when desired, be recirculated, by well known means not shown in the drawing, to the upper portion of the fractionator to regulate the vapor outlet temperature and to assist fractionation.

Residual liquid productsseparated from the vapors in reaction chamber 12 are withdrawn therefrom through line 30 and may pass, in part, to cooling and storage or to any desired further treatment through line 31 and valve 32. However, at least a portion if not all of the residual liquid passes from chamber 12 through valve 33,

' in line 30, into coking chamber 34, which is prefsidual material is reduced to substantially devolatilized coke. One or any number of a plurality of coking chambers may be employed and when a .plurality is used they may be operated alternately or simultaneously. For the sake of simplicity only one chamber is shown in the drawing.

Vapors are removed from the coking chamber through line 35 and valve 36 to fractionation in fractionator 37 wherein their relatively heavy components are condensed, passing therefrom through line 38 and valve 39 to pump 40 from which they are returned through line 41 and valve 42 to line 11, commingling therein with the heated oil dischargingfrom heating element '7, serving to partially cool the heated material and passing therewith to conversion in chamber 12. It is within the scope of the present invention to introduce all or a portion of the reflux condensate from fractionator 37 at any desired point or points in chamber 12 instead of or in conjunction with the introduction of a portion of this material into line 11, thus allowing more reaction time for the heated oil from heating element 7 before it is partially cooled and providing decreased reaction time for the cooling material.

The light components of the vapors resulting from the coking operation which are not condensed in fractionator 37 are withdrawn therefrom, together with uncondensable gas, through line 43 and may pass, all or in part, through valve 44, in line 43, to condenser 45, distillate and uncondensable gas from which passes through line 46 and valve 4'7 to be collected in receiver 48.

Uncondensable gas may be released from the receiver through line 49 and valve 50. Distillate 51 and valve 52.

A portion of the vapors and gases from fractionator 3'7, instead of passing to condensation and collection, may be diverted through line 53 and valve 54 to pump or compressor 55- from which they are directed through line 56, valve 57 and line 58 to heating element 59. In case all of the vaporous products from fractionator 3'7 are subjected to condensation, a portion of the resulting distillate collecting in receiver 48 is withdrawn through line 60 and valve 61 to pump 62 to be fed therefrom through line 58 and valve 63 to heating element 59 or, when desired, a portion of the vapors and gases from fractionator 37 and a portion ofthe distillate collected in-receiver 48 may each be supplied to heating element 59.

Heating element 59 is located in a furnace 66 of any suitable form and the material supplied to this zone is heated preferably to a higher temper ature than that employed in heating element '7, the heated materials being continuously discharged from heating element 59 through line 64 and valve 65 into coking chamber 34. The heated materials may enter the coking zone at any desired point, preferably entering at a low point in the chamber or at least below the level of residual oil therein. In this manner the heated materials from heating element 59 come into direct and intimate contact with the residual oil from chamber 12, serving to heat the residual oil and effect its reduction to coke and at the same time accomplishing substantial devolatilization of the coke produced. -Chamber-34 is provided with a drain line 67 controlled by valve 68.

Pressures employed within the system may range from substantially atmospheric to 800 pounds, or more, per square inch. Conversion temperatures employed may range from 850 to 1050 F., or thereabouts. The primary heating element wherein the raw oil charging stock and reflux condensate from the fractionator of the cracking system are treated, preferably employs a temperature of the order of 850 to 950 F., at the outlet from the heatingelement and a substantial superatmospheric pressure which may range, for example, from 100 to 500 pounds or more, per square inch. Approximately this same range of pressures may be employed in the reaction chamber of the cracking system while the pressure employed in the coking zone is substantially reduced,.relative to that in the reaction chamber and may range, for example, from substantially atmospheri to 100 pounds or thereabouts per square inch. The secondary heating element wherein final light products from the than those employed in the succeeding chambers of the respective systems.

The following example of specific operating conditions and results typifies the process of the invention as it may be practiced in the apparatus illustrated and described, although variations from the'specific operating conditions and results.

given may be employed without departing from the scope of the invention. The raw oil charging stock for the process is an 18 A. P. I. gravity Mid- Continent fuel oil, which, together with reflux condensate from the fractionator of the cracking system, is subjected in the primary heating element to a temperature of approximately 910 F. under a superatmospheric pressure of approximately 200 pounds per square inch. This temperature is reduced somewhat, prior to the introduction of the oil into the reaction chamber, by commingling reflux condensate fromthe fractionator of the coking system with the stream of heated oil. A pressure of about 200 pounds per square inch is maintained in the reaction chamber but the pressure in the coking chamber is reduced to slightly above atmospheric. A portion of the final light products from the coking operation are subjected in the secondary heating element to a temperature of approximately 1000 F. under a superatmospheric pressure of approximately 500 pounds per square inch and are thence introduced into the lower portion of the cokingchamber. This operation may yield, per barrel of charging stock, approximately 64% of motor fuel having an anti-knock value equivalent to an octane number of approximately 70, approximately 1150 cubic feet of gas and about 85 pounds of porous low volatile coke.

I claim as my invention:

1. In a process for the conversion .of hydrocarbon oil wherein the oil is subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating element and communicating reaction chamber, the va porous and residual liquid conversion products separated in said reaction chamber, residual liquid being removed from the reaction chamber and subjected to coking in a reduced pressure zone, the improvement which comprises subjecting vapors from the reduced pressure zone to fractionation whereby their heavycomponents are condensed and separated from their lighter components, subjecting a portion of said lighter components to further conversion in a separate heating element under more severe conversion conditions than the oil being heated in the first mentioned heating element, introducing the heated materials into the reduced pressure zone and introducing said relatively heavy condensed components of the vapors from the reduced pressure zone into the stream of heated oil passing from the heating element to the reaction chamher.

2. In a process for the conversion of hydrocarbon oil wherein the oil is subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating element and communicating reaction chamber, the vaporous and residual liquid conversion products separated in said reaction chamber, residual liquid being removed from the reaction chamber and subjected to coking in a reduced pressure zone, the improvement which comprises subjecting vapors from thereduced pressure zone to fractionation whereby their heavy components are condensed and separated from their lighter components, subjecting a portion of said lighter components to further conversion in a separate heating element under more severe conversion conditions than the material being treated in the first mentioned heating element, introducing the heated materials into the reduced pressure zone and commingling said relatively heavy condensed components of the'vapors resulting from coking with the heated oil discharged from the firstmentioned heating element into the reaction chamber. t

3. In a process for the conversion and coking of hydrocarbon oils which comprises subjecting an oil to conversion conditions of elevated temperature and superatmospheriopressure in a heating element, introducing the heated oil into an enlarged reaction chamber also maintained at superatmospheric pressure, where vaporous and residual liquid conversion products are separated, subjecting vapors from the reaction chamber to fractionation, returning the relatively heavy components of the vapors condensed by fractionation to the heating element for further conversion, subjecting the relatively light desirable components of the vapors to condensation and recovering the resulting products, withdrawing the residual liquid from the reaction chamber and introducing it, while still in a heated condition, into a reduced pressure coking chamber, subjecting vapors from the coking chamber to fractionation, commingling the relatively heavy components of the vapors from the coking chamber, which are condensed by fractionation, with the heated oil discharged from the firstmentioned heating element into the reaction chamber for further conversion, subjecting. a portion of the vapors and gases from the fractionator of the coking system to condensation, collecting the resulting distillate and gas, subjecting the remainder of said vaporous products to a temperature of the order of 900 to 1050" F., in a separate heating element at a superatmospheric pressure of the order of 200 to 800 pounds per square inch and introducing the thus heated vaporous products into the coking chamber.

4. A cracking process which comprises heating hydrocarbon oil to cracking temperature under. pressure while flowing in a restricted stream through a heating zone, discharging the heated oil into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing unvaporized oil from the reaction zone and flash distilling the same in a flashing zone by pressure reduction, fractionating the flashed vapors and commirfgling resultant I reflux condensate with said heated oil discharged JEAN ,DELA'lI'RE SEGUY.

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