US2064846A - Treatment of hydrocarbon oils - Google Patents

Description

Dec. 22, 1936. J. c. MORRELL 2,054,346

TREATMENT OF HYDROCARBON OILS Filed Dec. 5, 1931 FRACTIONATOR INVENTOR- JAC QUE C. MORRELL ATTOR Y E .ented Dec. 22, 1936 UNITED STATES PATENT OFFICE TREATIHENT F HYDROCABBON OILS,

Application December 5, 1931, Serial No. 579,217

2 Claims This invention relates to the treatment of hydrocarbon oils and particularly refers to the conversion of relatively heavy oils into lower boiling products of a more desirable character.

Primarily the invention comprises subjecting hydrocarbon oil to conversion conditions in a heating element, introducing the heated products into an enlarged reaction zone wherein vapors and residual liquid may be separated, subjecting the vapors to fractionation, returning the relatively heavy condensed components to further conversion, condensing, cooling and collecting the desirable light components, withdrawing residual oil from said reaction chamber and subjecting it to further vaporization in a zone of reduced pressure, withdrawing unvaporized residual oil from said zone of reduced pressure and subjecting the vapors evolved in this zone of fractionation condensing and cooling the desirable light components thereof, returning the relatively heavy condensed components of the vapors to further conversion in a separate heating element, introducing the heated products into the aforementioned enlarged reaction chamber and supplying raw oil charging stock for the system direct to either heating element or into the fractionator of the cracking system or into the fractionator of the residuum flash distilling system'or in any combination of these manners. Reflux condensate from the fractionator of the cracking system is preferably returned all or in part to the first mentioned heating element but may be supplied all or in part to the same heating element in which the reflux condensate from the fractionator of the residuum flash distilling system is treated, in which latter case all or a portion of the raw oil charging stock is preferably supplied directly to the first mentioned heating element. In any case the total raw oil charging stock is subjected to conversion in one or partially in each of the heating elements.

A more specific embodiment of the invention and a more comprehensive example of the features involved will be apparent with reference to the attached diagrammatic drawing which illustrates one form of apparatus in which the process of the apparatus may be practiced. Raw ,cil charging stock may be supplied through line I and valve 2 to pump 3 from which it may be fed through line A, line 5, valve 6 and line 1 directly into heating element 8 or, if desired, the raw oil supplied direct to the heating element may be first preheated by any well known means, not illustrated in the drawing, such as, for ex ample, by passing the raw oil in indirect contact with hot vapors or liquids within or withdrawn from the process. A portion or all of the raw oil may, if desired, be diverted from line 4 and fed through line 9 and valve Ill into fractionator H to assist fractionation :of the vapors in this zone, thereafter passing together with the relatively heavy components of the vapors which are condensed in this zone, through lines 6|, valve 62, pump 63, line 20 and valve 64 to further treatment in heating element 2|, as will be more fully described later, or all or a portion of the raw oil may be diverted from line 4 and may pass from pump 3 directly to heating element 2| through line 68, valve 69 and line 20. Likewise all or a portion of the raw oil may, if desired, be fed through valve l2, in line 4, into fractionator l3 where it may be preheated by indirect contact with the relatively hot vapors in this zone, assisting their fractionation and passing together with their relatively heavy condensed components through line I4 and valve I5 to pump l6. Reflux condensate from fractionator l3 or reflux condensate and preheated raw oil, as the case may be, may be fed by means of pump l6 through line fl and valve i! into heating element 8 or in case all or a portion of the raw oil is supplied directly to heating element 8, as previously described, a portion or all of the reflux condensate or reflux condensate and raw oil from fractionator l3 may be diverted from line 1 and fed through line l8, valve l9 and line 20 into heating element 2|. It will thus be apparent that the charging stock eventually reaches either heating element 8 or heating element 2| or is directed in part to each.

Heating element 8 may be located within a suitable furnace 22 and the oil supplied thereto may be heated to the desired conversiontemperature under any desired pressure conditions and preferably under a substantial super-atirrospheric pressure. The heated oil may be discharged through line 23, valve 24 and line 25 into reaction chamber 26. Preferably a substantial superatmospheric pressure is also employed in chamber- 26, which pressure may be substantially the same or lower than that employed in heating element 8. Vapors may be separated from residual liquid in chamber 26 and may pass through line 21 and valve 28 to fractionator I3 from which their relatively heavy insulficiently converted components which are condensed in this zone may be returned to retreatment, as already indicated. The relatively light desirable components of the fractionated vapors may pass through line 29 and valve 30, may be subjected to condensation and cooling in condenser 3|, uncondesable gas and distillate from which may pass through line 32 and valve 33 to collection in receiver 34. Uncondensable gas may be released from receiver 34 through line 35 and valve 36 while distillate may be withdrawn through line 31 and valve 38. A portion of the distillate may, if desired, be withdrawn from receiver 34 through line 39 and valve 40 to be recycled by means of pump 4| through line 42 and valve 43 to the upper portion of fractionator |3 to assist fractionation of the vapors in this zone.

Residual oil may be withdrawn from chamber 26 through line 44 and valve 45 to chamber 46 which is preferably maintained under substan tially reduced pressure relative to that employed in chamber 26 and in which further vaporization of the residual oil and final separation of the vapors and the residual product of the system may be eflected. Residual liquid, if produced, may be withdrawn from chamber 46 through line 41 and valve 48 to cooling and storage or to any desired further treatment.

Vapors from chamber 46 may pass through line 49 and, valve 50 to fractionation in fractionator I I. Relatively light vapor-s of the desired composition may be withdrawn from fractionator through line 5| and valve 52, may be subjected to condensation and cooling in condenser 53, products from which may pass through line 54 and valve 55 to be collected in receiver 56. Uncondensable gas may be released from the receiver through line 51 and valve 58. Distillate may be withdrawn through line 59 arid valve 60.

The relatively heavy components of the vapors subjected to fractionation in fractionator may be condensed in this zone and withdrawn through line 6| and valve 62 to pump 63 from which they may be fed through line 20 and valve 64 to heating element 2|. Heating element 2| may be located within any suitable form of furnace 65 and the oil supplied thereto, which may comprise reflux condensate from fractionator alone or reflux condensate and raw oil and, if desired, a portion of the reflux condensate from fractionator l3, may be heated to the desired conversion temperature under any desired pressure conditions and may pass from heating element 2| through line 66 and valve 61 into line 25 commingling therein with the heated oil discharged from heating element 8 and passing the'rewith to reaction chamber 26.

Attention is called to the fact that in all the various optional methods of flow through the system above illustrated and described all the raw oil supplied thereto is passed through either or in part to each of the heating coils without first introducing it to the reaction chamber, from" which a portion of it might be evacuated from the system with the flashed residuum. This is an important feature of the invention since it is well known to those skilled in the art that raw oil on a once-through operation will produce a much greater amount of light hydrocarbons than recycled stock, consequently the yield of light and valuable products is considerably greater where all the raw oil is passed through a heated conversion zone and introducing the heated oil into the reaction chamber than if the raw oil were first passed to the reaction chamber from which part of it would be evacuated from the system with the liquid residual conversion products without being given suflicient time under conversion conditions to form light conversion products. For this reason I expressly avoid any method of operation whereby raw oil is introduced to t e reacof conversion conditions is from 800 to 950 F. or

thereabouts and from 100 to" 500 pounds per sq. in. superatmospheric pressure in the heating elements and the reaction chamber of the system. Independently controlled conversion conditions are employed in each heating element and either heating element may employ more severe conversion conditions than the other, depending upon the charging stock, the particular flow employed in the process and the desired results, for example, when all or a major portion of a relatively heavy raw oil charging stock is subjected to conversion together with reflux condensate from the fractionator of the residuum flash distilling system and all or the major portion of the reflux condensate from the fractionator of the cracking system is processed in a separate heating element, said separate heating element preferably employs the more severe conversion conditions. On the other hand when all or the major portion of the reflux condensates from both fractionators is processed in one heating element and all or the major portion of a relatively heavy raw oil is subjected to conversion in a separate heating element, the first named heating element preferably employs the more severe conversion condi tions presuming, of course, that the process is operated for the maximum production of good quality motor fuel. Fractionating, condensing and collecting equipment of the cracking system may employ pressures substantially equalized with or lower than that employed in the reaction chamber. The residuum flash distilling system preferably employs relatively low pressures of the order of substantially atmospheric to pounds or thereabouts per sq. in.

As a specific example of the operation of the process of the present invention as it may be practiced in the apparatus illustrated, a 28 A. P. I. gravity topped crude is the raw oil charging stock substantially all of which is supplied to the fractionator of the residuum flash distilling system. The flash condensate from the fractionator of this system together with the preheated raw oil is subjected to a. conversion temperature of approximately 890 F. under a superatmospheric pressure of about 250 pounds per sq. in. Reflux condensate from the fractionator equivalent to a blend of approximately percent benzol and 35 percent Pennsylvania straight-run gasoline. In addition about 18 percent of good quality marketable fuel oil and about 7 percent of pressure distillate bottoms may be produced, the remaining products being uncondensable gas and a negligible percentage of coke or carbon.

In another operation a portion of the raw oil charging stock may be supplied to the primary heating element together with the reflux condensate from the primary fractionator and the flashed condensate together with the remainder of the raw oil is heated in the secondary heating element. The conditions of treatment in this case are preferably relatively milder and the total liquid recovery will be greater than in the above case but the yield of motor fuel and its antiknock value will be somewhat less. However, with lighter charging stock such as gas oils, kerosene, distillate and the like the reverse may be true when the flow just described is utilized and relatively more severe conversion conditions are employed.

I claim as my invention:

1. A cracking process which comprises heating hydrocarbon oil to cracking temperature in a heating zone and thence discharging the same into a separating zone, separately removing vapors and unvaporized oil from the separating zone, partially condensing the vapors to separate heavier fractions thereof, flash distilling the unvaporized oil by pressure reduction, independently fractionating the flashed vapors thereby forming flash reflux, combining such reflux with reflux condensate formed by said partial condensing step and subjecting the resultant mixture to independently controlled cracking conditions of temperature and pressure in a second heating zone, discharging the thus heated mixture into the separating zone, and finally condensing the fractionated flashed vapors and the vapors'uncondensed by said partial condensing step.

2. A cracking process which comprises heating hydrocarbon oil to cracking temperature in a heating zone and thence discharging the same into a separating zone, separately removing vapors and unvaporized oil from the separating zone, partially condensing the vapors to separate heavier fractions thereof, flash distilling the unvaporized oil by pressure reduction, independently fractionating the flashed vapors thereby forming flash reflux, combining such reflux with reflux condensate formed by said partial condensing step and subjecting the resultant mixture to independently controlled cracking conditions of temperature and pressure in a second heating zone, discharging the thus heated mixture into the separating zone, supplying another portion of the reflux condensate formed in said first-named fractionating step to the first-mentioned heating zone, and finally condensing the fractionated flashed vapors and the vapors uncondensed by said partial condensing step.

J ACQUE C. MORRELL.

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