US2086004A - Conversion of hydrocarbon oils - Google Patents

Description

July 6, 1937. K. swARTwooD 2,086,004

CONVERSION OF HYDROCARBON 611$ Filed June 27, 1934 FURNACE 2 FURNACE INVENTOR KENNETH SWARTWOOD ATTORNEY Patented July 6, 1937 UNITED STATES CONVERSION or HYDROCARBON OILS Kenneth Swartwood, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application June 27, 1934, Serial No. 732,606

3 Claims.

This invention particularly refers to animproved process and apparatus for the selective conversion of relatively low-boiling and highboiling oils. It is particularly directed to the treatment of hydrocarbon oilcharging stocks of relatively Wide boiling range, providing for fractional distillation of the charging stock accompanied by relatively mild conversion of its highboiling fractions (ordinarily termed viscosity breaking) accomplished without passing the same through a heating coil and provides for further conversion of the lower boiling fractions of the charging stock and the vaporous products resulting from relatively mild conversion of the highboiling fractions of the intermediate conversion products of the process together with vaporous products resulting from more severe conversion of the low-boiling fractions of the intermediate conversion products. One specific embodiment of the present invention may comprise subjecting a relatively lowboiling hydrocarbon oil, recovered from within the system, to relatively high conversion temperature at substantial superatmospheric pressure in a heating coil, introducing the highly heated products into a high-pressure reaction chamber wherein continued conversion, particularly of their vaporous components, is accomplished, withdrawing both vaporous and .liquid conversion products from the reaction chamber and introducing the same into a reduced pressure. vaporizing chamber, withdrawing residual liquid from the vaporizing chamber, subjecting vapor-' ous products from the vaporizing chamber to fractionation whereby their insufficiently con verted components are condensed as reflux condensate and separated into selected relatively low-boiling and high-boiling fractions, subjecting fractionated vapors of the desired end-boiling point to condensation and recovering the resulting distillate, returning the relatively low-boiling fractions of the reflux condensate, which comprise said relatively low-boiling oilsrecovered from within the system, to the heating coil for further conversion, subjecting the relatively high-boiling fractions of the reflux condensate to milder conversion temperature at substantial,

of relatively wide boiling range, into the last mentioned reaction chamber whereby its relatively low-boiling and high-boiling fractions are separated and the latter are subjected to a relatively mild conversion or viscosity breaking operation, withdrawing non-vaporous residual liquid from the last mentioned reaction chamber and, when desired, introducing all or a regulated portionthereof into the reduced pressure vaporizing chamber, withdrawing vaporous products from 1 the last mentioned reaction chamber, including said relatively low-boiling fractions of the charg-r ing stock and the vaporous products resulting from the relatively mild conversion of said high! is subjected therein to a relatively high conver- I sion temperature, preferably at substantial superatmospheric pressure, by means of heat derived from the furnace. The stream 'of highly heated products is discharged from the heating coilv through line 3 and valve 4 and is introducedinto reaction chamber 5 wherein its vaporous components commingle with other vaporous materials from within the system, supplied to this zone, as will be later more fully described, and wherein the commingled vapors are subjectedto continued conversion. V

Chamber 5 is also preferably operated at a substantially superatmospheric pressure and, although not illustrated in the drawing, itis preferably insulated to prevent the excessive loss of heat by radiation so that continued conversion of the heated materials supplied to this zone, and particularly their vaporous components, is accomplished therein. Both vaporous and liquid conversion products are, in the particular case here illustrated, withdrawn incommingled state from the lower portion of chamber 5 through line 6 and valve 1 and are .introduced intovaporizing chamber 8. Y Chamber. 8 is preferably operated at a sub-,- stantially reduced pressure'relativeto that employed in chamber 5 by means of which further vaporization of the liquid conversion products supplied to this zone is accomplished. Vaporous and liquid conversion products are separated in chamber 8 and the residual liquid may be withdrawn therefrom through line 9 and valve ID to cooling and storage or to any desired further treatment while the vaporous products pass from the upper portion of chamber 8 through line II and valve I2 to fractionation in fractionator I3.

The components of the vaporous products supplied to fractionator I3 boiling above the range of the desired final light distillate product of the process are condensed in this zone as reflux condensate and the reflux condensate is separated by fractional distillation in this zone into selected relatively low-boiling and high-boiling fractions. Fractionated vapors of the desired end-boiling point, comprising materials within the boiling range of the desired final light distillate product of the process and uncondensable gas produced by the operation, are Withdrawn from the upper portion of fractionator I3 through line I 4 and valve I 5 to condenser I6 wherein they are subjected to condensation and cooling. The resulting distillate and uncondensable gas passes from condenser I6 through line I1 and valve I8 to collection and separation in receiver I9. Uncondensable gas may be released from the re ceiver through line I9 and valve 20. The distillate collected in receiver I8 may be withdrawn therefrom through line 2| and valve 22 to cooling and storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver I8 may be recirculated by well known means, not illustrated, to the upper portion of fractionator I3 to serve as a cooling and refluxing medium in this zone whereby to assist fractionation of the vapors and, maintain the desired vapor outlet temperature from the fractionator.

The selected relatively low-boiling fractions of the reflux condensate formed in fractionator I3 may be withdrawn from one or a plurality of suitable intermediate points in the fractionating column, passing, for example, through line 23 and valve 24 to pump 25 by means of which this relatively low-boiling oil is supplied through line 26 and valve 21 to heating coil I, for further conversion as already described.

The relatively high-boiling fractions of the reflux condensate formed in fractionator I3 may be withdrawn from the lower portion of this zone through line 28 and valve 29 to pump 30 by means of which this material is supplied through line 3I and valve 32 to further conversion in heating coil 33.

A furnace 34 of any suitable form supplies the required heat to the oil passing through heating coil 33 to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure. Preferably, the conversion temperature to which the relatively high-boiling oil is subjected in heating coil '33 is milder than the temperature employed in heating coil I for treatment of the relatively low-boiling oil. The heated products are discharged from heating coil 33 through line 35 and valve 36 and are introduced into reaction and separating chamber 31 which is also preferably operated at a substantial superatmospheric pressure and wherein vaporous conversion products are separated from the residual liquid conversion products.

Simultaneous with the operation above described, charging stock' for the process, prefer-' ably comprising an oil of relatively wideboiling range, such as crude petroleum, topped crude or the like, is supplied through line 33 and valve 39 to pump 40 by means of which it is fed through line 4| and may be directed, all or in part, either through valve 42 in this line into line 35, to commingle therein with the stream of heated products passing from heating coil 33 into chamber 31, or it may be directed, all or in part, from line 4I through line 43 into reaction chamber 31, entering this zone at any desired point or plurality of points either above or below the point of introduction of the heated products from heating coil 33, as indicated in the drawing, by means of lines 44 and valves 45.

The charging stock supplied to chamber 31,

either directly or by way of line 35, serves to partially cool and retard further conversion and vaporization of the heated products from heating coil 33 and the charging stock is thereby subjectedto heating and to substantial vaporization in chamber 31. The charging stock may, of course, be preheated in any well known manner, not illustrated in the drawing, prior to its introduction into line 35 and/or chamber 31. However, the quantity and temperature of the charging stock supplied to chamber 31 will ordinarily be such that conversion in this zone is substantially limited to the relatively high-boiling fractions of the charging stock and of the conversion products from heating coil 33.

.The residual liquid remaining unvaporized in chamber 31, including relatively high-boiling fractions of the charging stock or the residual liquid resulting from its relatively mild conversion in chamber 31 and the residual liquid result ing from conversion of the relatively high-boiling fractions of the reflux condensate, is withdrawn from the lower portion of chamber 31 through line 46 and may pass, all or in part, through valve 41 to cooling and storage or elsewhere, as desired, or may be directed, all or in part, from line 46 through line 48 and valve 43 into vaporizing chamber 8, wherein it is subjected to further vaporization for the recovery of any desirable relatively low-boiling components suitable as cracking stock for treatment within the system, which latter pass together with other vaporous products from chamber 8 to fractionation in fractionator I3, as already described.

Vaporous materials evolved from the charging stock in chamber 31, as well as the vaporous conversion products from heating coil 33 remaining uncondensed in chamber 31 are withdrawn from the upper portion of this zone through line 50 and valve 5| and are introduced into reaction chamber 5 wherein they commingle with the more highly heated vaporous products from heating coil I, serving to partially cool the same and prevent their excessive further conversion, and are subjected to continued conversion therewith in the reaction chamber and to the subsequent treatment already described.

The preferred range of operating conditions which may be employed in accordance with the provisions of the present invention, in an apparatus such as illustrated and above described, may be approximately as follows: The heating coil to which the relatively low-boiling fractions of the reflux condensate are supplied may utilize a conversion temperature measured at the outlet therefrom ranging, for example, from 900 to 1000 F., preferably with a superatmospheric pressure at this pointin the system of from 200 to 500 pounds, or more, per square inch. The succeeding reaction chamber may be operated at substantially the same pressure as that employed at the outlet from the high-temperature. heating 1 :p a ay pl a s mew a ired ced superatmospheric pressure. The heating coil to which the relatively high-boiling fractions of the reflux condensate aresupplied preferably em ploys an outlet conversion temperature of from 850 to 950 F., with a superatmospheric pressure, measured atthis point in the system, of from 100 to 500 pounds, or thereabouts, per square inch. Any desired pressure within substantially the same range may be employed in the succeeding reaction and separating chamber which pressure, however, is preferably not less than that employed in the reaction chamber to which the vaporous products from this zone are supplied. The vaporizing chamber 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. The fractionating, condensing and collecting portions of the system may employ substantially the same or somewhat reduced pressures relative to that employed in the vaporizing chamber.

As a specific example of the operation of the process of the present invention, as it may be accomplished in an apparatus such as illustrated and above described, utilizing as charging stock a California crude of about 16 A. P, I. gravity, the light reflux heating coil employs an outlet conversion temperature of about 970 F. and a superatmosphe'ric pressure of approximately 400 pounds per square inch which is reduced to approximately 250 pounds per square inch in the succeeding reaction chamber. A conversion temperature of approximately 920 F. is employed at the outlet from the heavy reflux heating coil with a superatmospheric pressure slightly in excess of 250 pounds per square inch at the outlet from this heating coil and in the succeeding reaction and separating chamber. The charging stock is commingled with the stream of heated products passing from the heavy reflux heating coil into the reaction and separating chamber. The Vapors from the last mentioned reaction chamber are supplied to the first mentioned reaction chamber wherein they are subjected to continued conversion and from which the vaporous and liquid products pass to a vaporizing chamber operated at a superatmospheric pressure of about 50 pounds per square inch. Residual liquid from the last mentioned reaction chamber is also supplied to the vaporizing chamber. The pressure employed in the vaporizing chamber is substantially equalized in the succeeding fractionating, condensing and collecting portions of the system. This operation may produce, per barrel of charging stock, about 50 percent of 385 F. endpoint motor fuel having an octane number of approximately 72 and about 40 percent of good quality residual liquid suitable as fuel, the remaining percent, or thereabouts, being chargeable, principally to uncondensable gas and loss.

I claim as my invention:

1. In a process for the conversion of hydrocarbon oils wherein a relatively low-boiling oil recovered from within the system is subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, the resulting vaporous and liquid conversion products separated in a reduced pressure vaporizing chamber, the vaporous conversion products subjected to fractionation, whereby their insufliciently converted components are. condensed as reflux condensate and separated: into selected relatively low-boiling and high-boiling fractions, fractiona ated vapors 'ofithe desired e'ndeboiling point sub.-

jectedhto condensation, the resulting distillate re covered, said low-boiling fractions of the reflux condensate returned totheheating coil for furtherconversion and-said high boiling fractions of the reflux condensate subjected to less severe conversion conditions of elevated temperature and superatmospheric pressure in a separate heating coil, the improvement which comprises introducing heated products from the last mentioned heating coil into a separate reaction chamber, also operated at superatmospheric pressure, and commingling therewith charging stock for the process, comprising an oil of relatively wide boiling range, vaporizing a substantial portion of thecharging stock in said separate chamber, introducing vaporous products from said separate reaction chamber, comprising vapors of the charging stock and vaporous products resulting from said conversion of the high-boiling fractions of the reflux condensate, into the first mentioned reaction chamber whereby they are commingled and subjected to further conversion with the vaporous products from the first mentioned heating coil, and supplying residual liquid, comprising unvaporized portions of the charging stock and residual products resulting from said conversion of the high-boiling fractions of the reflux condensate, to the vaporizing chamber in regu lated quantities for further vaporization.

2. A conversion process which comprises fra c tionating hydrocarbon vapors to form a relatively heavy reflux condensate and a lighter reflux condensate, heating the latter to cracking temperature under pressure in a heating coil and then introducing the same to a reaction zone, simultaneously heating the heavy reflux condensate under pressure to lower cracking temperature in a second heating coil and discharging the same into a separating zone maintained under pressure, introducing charging oil for the process to said separating zone and therein vaporizing a substantial portion thereof, separating volatilized portions of the charging oil and of the heavyreflux condensate from unvaporized oil in the separating zone, introducing such volatilized portions to said reaction zone for conversion therein in admixture with the heated lighter reflux condensate from the first-named coil, removing the conversion products from the reaction zone and introducing the same to a vaporizing zone maintained under lower pressure than the reaction zone and said separating zone, discharging unvaporized oil from said separating zone into the vaporizing zone and separating vapors from residue in this zone, supplying the former to the fractionating step as said hydrocarbon vapors, and finally condensing the fractionated vapors,

3. A conversion process which comprises fractionating hydrocarbon vapors to form a relatively heavy reflux condensate and a lighter reflux condensate, heating the latter to cracking temperature under pressure in a heating coil and then introducing the. same to a reaction zone,

simultaneously heating the heavy reflux conden a substantial portion thereof, separating the ree sultant vapors of the charging oil and of the heavy reflux condensate from unvaporized oil in the separating zone, introducing the last-named vapors to said reaction zone for conversion therein in admixture with the heated lighter reflux condensate from the first-named coil, removing the conversion products from the reaction zone and introducing the same to a vaporizing zone maintained under lower pressure than the reaction zone and said separating zone, discharging unvaporized oil from said separating zone into the vaporiizng zone and separating vapors from residue in this zone, supplying the former to the fractionating step as said hydrocarbon vapors, and finally condensing the fractionated vapors.

KENNETH SWAR'I'WOOD.

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