US1983688A - Treatment of hydrocarbon oils - Google Patents

Description

Dec; 11, 1934. c. H. ANGELL TREATMENT OF HYDROCARBON OILS Filed March 11, 1932 FURNACE l7 INVENTOR CHARLES H. ANGELL BY Mfi ATTORN Patented Dec, rarest re r orricr 1,983,688 TREATWNT 0F HYDRQCARBUN @lllLS Application March H, 1932, Serial No, 598,142

3 (Claims. (Ch ltd-58) This invention particularly refers to the simultaneous conversion of separate charging stocks of diiferent characteristics accompanied by reduction of the residual conversion products to substantially dry carbonaceous material.

Maximum yields of desirable light products are obtainable from relatively heavy hydrocarbon oil by reduction of the residual liquid products re-. sulting from the primary conversion thereof to coke, by continued conversion of the vaporous products after separation of said residual oil and by return of the intermediate conversion products (reflux condensate) to further conversion.

In its broad aspects, the invention comprises the use of a secondary charging stock of relatively light nature in conjunction with the conversion and coking of a relatively heavy oil and its novelty resides in the advantageous method and means whereby said secondary charging stock, after its subjection to independently controlled conversion conditions, is utilized to effect further conversion of the vaporous products resulting from the primary conversion of the relatively heavy charging stock after separation therefrom of residual liquid products, following which-the heat attained by the commingled vaporous conversion products is partially dissipated by direct contact of the vaporous products with said residual liquid in a zone of reduced pressure for the purpose of reducing the latter to coke.

By use of the invention, conversion of relatively heavy charging stock may be accomplished under relatively mild conditions which preclude any substantial formation and deposition of coke in the heating element, following which the vaporous products of this reaction may be subjected to continued conversion, together with vaporous products from conversion of the relatively light charging stock, under more severe conversion conditions which favor the production of materials of high antilrnock value, while residual products of both the primary and secondary conversions are subjected to coking under-reduced pressure conditions which favor devolatilization and the maximum recovery of vaporizable components; all of which is accomplished in a unified cracking system employing a minimum of equipment and a high degree of flexibility, with respect to permissible operating conditions, to accommodate various charging stocks.

One specific form of apparatus incorporating the features of the present invention is illustrated by the attached diagrammatic drawing. Amore detailed description of the invention, as it may be practiced in the apparatus illustrated, is included in the following description of the drawing.

Relatively heavy oil such as, for example, residual oil, fuel oil, crude, gas oil and the likewhich, for the purpose of convenience, may be designated as primary charging stock may be supplied through line 1 and valve 2 to pump 3 from which it is fed through line 4 and valve 5 to heating element 6. The primary heating element is located I in a furnace 7 of any suitable form and the oil supplied to this zone is heated, preferably at substantial super-atmospheric pressure, to the desired conversion temperature and is thence dis charged through line 8 and valve 9 into reaction chamber 10.

Substantial super-atmospheric pressure is also preferably employed in chamber 10 and the heated oil from heating element 6 is preferably discharged into the lower portion of this zone wherein residual liquid products quickly separate from the vaporous products, preferably being withdrawn therefrom, substantially as fast as they accumulate, while still in a highly heated condition and without being subjected to any appreciable further conversion in the reaction zone.

Simultaneous with the introduction of mate-- rials from heating element 6 into chamber 10, t

stantial super-atmospheric pressure, to a higher temperature than that to which the primary charging stock is subjected in heating element 6. Heated materials from heating element 16 are discharged through line 18 and valve 19 also into reaction chamber 10, preferably entering this zone at a point above the point of introduction of products from heating element 6. In this manner the relatively hot materials from heating element 16 are substantially prevented from contacting the residual oil which separates in the lower portion of the reaction chamber but are intimately contacted and commingledwith the vaporous conversion products from heating element 6 which pass upward through the reaction zone, serving to heat these products preferably to a somewhat higher temperature than that attained in heating element 6. It is thus evident that the vaporous conversion products from both heating element 6 and heating element 16 are subjected to continued conversion for a predetermined time under the pressure conditions maintained in chamber 10 while the non-vaporous residual products from both heating elements are quickly separated from the vapors and may be withdrawn from the reaction zone without substantial further conversion.

Residual liquid is withdrawn from the lower portion of the reaction zonethrough line 20 and valve 21 and is introduced into coking chamber 22, preferably entering the upper portion of this zone. Relatively hot vaporous products from the upper portion of the reaction zone pass through line 23 and valve 24 into coking chamber 22, preferably entering the lower portion of this zone or at least below the level of residual oil introduced thereto.

The coking chamber is preferably operated at reduced pressure relative to that employed in the reaction zone and by means of the pressure reduction and intimate counter-current contact between the residual oil and the relatively hot vaporous products from the reaction zone, further vaporization and coking of the residual oil is efiected. The coke is allowed to accumulate within the coking chamber to be removed therefrom after the chamber has become substantially filled or after the operation of the process is completed and, when desired, a plurality of coking chambers may be employed to provide more space for the accumulation of coke and permit prolonged operation. When a plurality of coking chambers are used they may be operated simultaneously or, preferably, are alternately operated and cleaned. The use of a plurality of coking zones to permit prolonged operation is well known and for the sake of simplicity only one coking zone is illustrated in the drawing.

Vapors from the coking zone pass through line 25 and valve 26 to fractionation in fractionator 27 by means of which their insufficiently converted relatively heavy components are condensed, collecting within the lower portion of the fractionator to be withdrawn therefrom through line 28 and valve 29 to pump 30 from which they are fed through line 31 and either through line 32, valve 33 and line 4 to heating element 6, for further conversion together with the primary charging stock, or through valve 34, in line 31, and line 14 to heating element 16, for further conversion together with the secondary charging stock. The heating element to which the reflux condensate from fractionator 27 is returned to further conversion will depend upon which employs conditions best suited for the conversion of the refiux condensate to produce maximum yields of the desired light product. This in turn will depend, to a large extent, upon the nature of the primary and secondary charging stocks. As the quantity and character of the reflux condensate itself will vary with different primary and secondary charging stocks and with different operating conditions the treatment to which this intermediate product is best suited must be determined for'each type of charging stock and each set of operating conditions.

Desirable light vapors and gases pass from the upper portion of the fractionator through line 35 and valve 36, are subjected to condensation and cooling in condenser 37, distillate and uncondensable gas from which passes through line 38 eeaeaa and valve 39 to be collected in receiver 40. Uncondensable gas may be released from the receiver through line 41 and valve 42. Distillate may be withdrawn from this zone through line 43 and. valve 44.

It will be understood that any of the well known expedients applicable to the process of the present invention such as, for example, returning a portion of the distillate from the receiver of the system to the fractionator for cooling, preheating a portion of all of either or both charging stocks by heat recovered from the system etc., may be employed although not illustrated in the drawing. Conversion temperatures employed at the outlet from the primary heating element may range, for example, from 800 to 950 F. or thereabouts. Preferably substantial super-atmospheric pressures of the order of 100 to 500 pounds, or more, per square inch are employed in the primary heating element and in the reaction tively low pressure ranging, for example, from substantially atmospheric to 100 pounds or thereabouts per square inch is preferred in the coking zone and this pressure may be substantially equalized or somewhat reduced in the succeeding fractionating, condensing and collecting portions of the system.

As an example of specific operating conditions which may be employed in the operation of the invention and results obtainable therefrom, a 19 A. P. I. gravity Mid-Continent fuel oil may be the heavy charging stock which is subjected in the primary heating element to a temperature of approximately 900 F. at a superatmospheric pressure of approximately 400 pounds per square inch. The light charging stock may be a 40 A. P. I. gravity naphtha which is subjected in the secondary heating element to a temperature of approximately 900 F. at a super-atmospheric pressure of about 500 pounds per square inch. Heated products from both heating elements are introduced into the lower portion of the reaction chamber, which is maintained at a pressure of approximately 400 pounds per square inch. Reflux condensate from the fractionator of the system may be returned to the primary heating element for treatment, together with the heavy charging stock. The residual oil, withdrawn from the lower portion of the reaction chamber at a temperature of approximately 860 F., is introduced. into the upper portion of the coking zone wherein it is counter-currently contacted with vapors withdrawn from the upper portion of the reaction chamber at a temperature of approximately 925 F. Substantially atmospheric pressure is maintained in the coking zone and in the succeeding fractionating, condensing and collecting :portions of the system. About equal parts by volume of light and heavy charging stock are used and the operation may yield, per barrel of total charging stock, about percent of motor fuel having an antiknock value equivalent to an octane number of approximately 75, about 55 pounds of coke and about 890 cubic feet of uncondensable gas.

As a specific example of a somewhat difierent type of operation which may be practiced in accordance with the principles of the invention, in the same apparatus, the primary charging stock is a Pennsylvania crude of about 40 A. P. I. gravity containing a substantial proportion of gasoline and it is subjected in the primary heating element to atemperature of about 900 F. at a superatmospheric pressure of approximately 500 pounds per square inch. The secondary charging stock is a Pennsylvania kerosene distillate of about 38 A. P. I. gravity which is subjected in the secondary heating element, together with reflux condensate from the fractionator of the system, to a temperature of approximately 970 F. at a super-atmospheric pressure of approximately 500 pounds per square inch. Approximately this same pressure is utilized in the reaction chamber and is reduced in the coking chamber and succeeding portions of the system to a pressure of approximately 30 pounds per square inch. The hook-up above illustrated and described is utilized between the reaction and coking chambers. Again. utilizing about equal parts of primary and secondary charging stock, this operation may yield, per barrel of total charging stock, about 72 percent of motor fuel having an octane number of approximately 80, about 30 pounds of coke and about 1000 cubic feet of uncondensable gas.

I claim as my invention:

1. A hydrocarbonoil cracking process which comprises passing a relatively heavy oil through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into the lower portion of a substantially vertical reaction zone maintained under cracking conditions of temperature and pressure, separating the heated oil into vapors and unvaporized oil in the lower portion of the reaction zone and rapidly withdrawing the unvaporized oil to prevent appreciable liquid accumulation in the reaction zone, simultaneously heating a lighter oil in a second cracking zone to higher cracking temperature than said heavy oil and then discharging the same into the reacttion zone a substantial distance below the top thereof and above the point of introduction of said heated oil, thereby preventing contact between the vapors of the lighter oil and said unvaporized oil and commingling the lighter oil vapors with the first-mentioned vapors, passing the commingled vapors upwardly through-the reaction zone and removing the same from the upper portion thereof, and fractionating and condensing the withdrawn vapors.

2. A hydrocarbon oil cracking process which comprises passing a relatively heavy oil through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into the lower portion of a substantially vertical reaction zone maintained under cracking conditions of temperature and pressure, separating the heated oil into vapors and unvaporized oil in the lower portion of the reaction zone and rapidly withdrawing the unvaporized oil to prevent appreciable liquid accumulation in the reaction zone, simultaneously heating a lighter oil in a second cracking zone to higher cracking temperature than said heavy oil and then discharging the same into the reaction zone a substantial distance below the top thereof and above the point of introduction of said heated oil, thereby preventing contact between the vapors of the lighter oil and said unvaporized oil and commingling the lighter oil vapors with the firstmentioned vapors, passing the commingled vapors upwardly through the reaction zone and removing the same from the upper portion thereof, contacting the withdrawn vapors and unvaporized oil in a distillation zone maintained under lower pressure than the reaction zone to evolve additional vapors from the unvaporized oil, removing the vaporous mixture from the distillation zone and subjecting the same to fractionation and condensation.

3. The process as defined in claim 1 further characterized in that said lighter oil comprises a gasoline-containing distillate.

CHARLES H. ANGELL.

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