US2247740A - Conversion of hydrocarbon oils - Google Patents

Description

July 1, 1941. c. H. ANGELL CONVERSION OF HYDROCARBON OILS Filed Dec. 31. 1937 CONDEN| SER a0 FRACTIONATOR\ RECEIVER 1 All til.

m o 9 a D v 0 a 6 fl u N F W R M 2 3 a! m a a m 3 4 3 M m M M 4 4 wU HT m L m c I C 2 a H mm r F 3 3 a u n z HHH 5 2 u a 7 6 1|; 2 2 5 2 .51 :ad dv u n E 3? I zE-Ev m E? W m f g. 8 1 a 9 4 w. o m o J INVENTOR CHARLES H. ANGELL A TORNEY Patented July 1, 1941 2,247,740 CONVERSION OF HYDROCARBON OILS Charles H. Angeli, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 11]., a

corporation of Delaware Application December 31, 1937, Serial No. 182,705

2 Claims.

The invention proved to which said low-boiling fractions are supplied, the commingled materials passed through an enlarged reaction chamber maintained at superatmospheric pressure and her wherein their vaporous components are subiected to continued cracking at a higher temperature than that maintained in the first reaction chamber and in commingled state with additional hot conversion products supplied thereto from a separate operations and for further cracking to said separate heating coil.

The features of the invention, above outlined, permit a high degree of flexibility with respect to the conditions of cracking under which the selected low-boiling and high-boiling fractions ing fractions of the charging stock, obviates the excessive production of coke and gas which is often encountered when such relatively highboiling oils are cracked in a heating coil and the use of two serially connected enlarged reaction chambers, in the manner provided by the invention, permits independent control or temperature, pressure and cracking time employed in various stages of the cracking operation.

The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the features invention, may be conducted.

The charging stock, which is supplied to the fractional distilling step of the process, preter- When desired, regulated quantities of the distillate collected in receiver 9 may be recirculated by well known means, not illustrated, to the upper portion of column 3 to serve as a cooling and refluxing medium in this zone.

When the charging stock contains a substantial quantity of gasoline or low-boiling gasoline fractions of satisfactory antiknock value they are preferably separated in fractionator 3 from the higher boiling components of the charging stock and recovered as distillate from receiver 9.

When the charging stock does not contain any substantial quantity of good antiknock gasoline or gasoline fractions, its total components which boil within the range of gasoline and, when desired, somewhat higher boiling components of the nature previously mentioned, are preferably collected as distillate in receiver 9 and supplied therefrom in regulated quantities through line H and valve l5 to pump l6 by means of which they are fed through line I! and valve l3 to heating coil l3, wherein they are subjected to cracking treatment in the manner subsequently described.

When only good antiknock gasoline or gasoline fractions are collected as distillate in receiver 3, any higher boiling gasoline fractions of unsatisfactory antiknock value are preferably removed as condensate from a suitable intermediate point in column 3, in which case, somewhat higher boiling components of the charging stock such as heavy naphtha fractions, kerosene or kerosene distillate and the like are preferably removed from the same or a separate intermediate point in this zone and directed, with the.high-boiling, poor antiknock gasoline fractions, to cracking treatment in heating coil N. In the case here illustrated, provision is made for directing such selected intermediate fractions of the charging stock (consisting predominantly of heavy gasoline fractions of inferior antiknock value and somewhat higher boiling materials) from column 3 through line and valve 2| to pump 22 by means or which they are supplied through line 23 and valve 24 to heating coil l9.

Heating coil I9 is disposed within a suitable furnace 25 by means of which the materials passing through the heating coil are heated to the desired relatively high cracking temperature at a substantial superatmospheric pressure. The temperature and pressure conditions employed in heating coil l3 are regulated to effect a material improvement in the antiknock value of the gasoline or heavy gasoline fractions supplied to this zone and to simultaneously convert any higher boiling oils, of the nature previously mentioned, which are supplied to this zone, into substantial yields of good antiknock gasoline. The resulting highly heated products are discharged from heating coil l9 through line 26 and valve 21 and, preferably after being partially cooled in the manner subsequently described, are introduced into reaction chamber 23.

The selected high-boiling or residual liquid fractions of the charging stock, which remain unvaporized and/or are condensed as reflux condensate in column 3, are directed from the lower portion of this zone through line 29 and valve 30 to pump 3| by means of which they are supplied through line 32 and valve 33 to reaction chamber 26.

Preferably, the relatively cool high-boiling oil from the lower portion of column 3 is directly commingled in line 26 with the highly heated products discharged from heating coil I3, whereby the latter are partially cooled prior to their introduction into chamber 28. However, when desired, all or a regulated quantity of the highboiling oil may be supplied directly to chamber 23, by well known means not shown, and therein commingled with the products supplied to this zone from heating coil l3.

Chamber 23 is preferably maintained at a substantial superatmospheric pressure, which may be substantially the same or lower than that employed at the outlet of heating coil l9. Although not indicated in the drawing, chamber 23 is also preferably insulated to conserve heat so that the commingled materials passing through this zone, and particularly the high-boiling oils supplied thereto from column 3, will undergo appreciable cracking therein under milder conversion conditions than those employed in heating coil IS. The vaporous and liquid conversion products resulting from cracking of the commingled materials in chamber 28 are directed from the lower portion of this zone, preferably in commingled state, through line 34 and valve 35 into reaction chamber 36, to which hot conversion products from heating coil 64 are also supplied, as will be later described.

Chamber 36 is also preferably operated at a substantial superatmospheric pressure, which may be substantially the same or lower than that employed in chamber 23. Chamber 33 is also preferably insulated to conserve heat, although insulation is not indicated in the drawing, and the hot conversion products supplied to chamber 36 from heating coil 54 supply additional heat to the products supplied to this zone from chamber 28. The products from heating coil 64 and chamber 28 may be separately supplied to chamber 36, as illustrated, or they may be commingled prior to their introduction into this zone. Preferably, in either case, they are introduced into the lower portion of chamber 36. By this method of operation, the heavy liquid components of the materials supplied to chamber 36 may be quickly removed from the lower portion of this zone without being subjected to any substantial continued cracking time therein, or at least without being subjected to continued cracking for as long a time as the vaporous components of the materials supplied to this zone. By supplying additional heat to the liquid products supplied from chamber 23 to chamber 36 and, when desired, by maintaining a somewhat lower pressure in chamber 36 than that utilized in chamber 28, appreciable vaporization of the liquid products supplied to chamber 36 is accomplished in this zone and the evolved vapors, together with the materials supplied to chamber 36 in vaporous state, are directed upwardly through this zone and subjected during their passage therethrough to more prolonged continued cracking than the non-vaporous components.

In the particular case here illustrated, the heavy liquid products which remain unvaporized in chamber 36 are removed from the lower portion of this zone, either alone or together with a regulated minor portion of the vaporous products supplied thereto, and are directed through line 31 and valve 33 into vaporizing and separating chamber 39.

Substantially all of the vaporous products, or that portion of the vaporous products not removed from the lower portion of chamber 36 with the liquid products, are separately removed from the upper portion of this zone and may be directed through line 40 and valve M to fractionation in fractionator 42 or they may be directed, all or in part, from line Ill through line 43 and valve 44 into chamber 39, to commlngle with and assist further vaporization of the liquid products supplied to the latter zone.

Chamber 3! is preferably operated at a substantially reduced pressure relative to that employed in chamber 36, by means of which appreciable further vaporization of the liquid products supplied to this zone is accomplished. Separation of vaporous and non-vaporous conversion products is accomplished in chamber 39 and, when this zone is operated for the production of liquid residue, the latter may he removed from the lower portion of the chamber through line 45 and valve 45 to cooling and storage or to any desired further treatment. When desired, however, the conditions of operation may be so controlled that only coke will remain as the nonvaporous residue in chamber 39. In the latter case, a plurality of coking chambers similar to chamber 39 may be employed. although not illustrated, and preferably are operated alternately so that the coking stage, in common with the rest of the system, is continuous. Vaporous products evolved in chamber 39, as well as any materials supplied thereto in vaporous state, are directed from the upper portion thereof through line 41, valve 48 and line 40 to fractionation in fractionator 42.

Components of the vaporous products supplied to fractionator 42 which boll above the range of the desired final light distillate product of the cracking operations are condensed in this zone as reflux condensate. The latter is directed from the lower portion of fractionator 42 through line 48 and valve 50 to pump by means of which it is supplied through line 52 and valve 53 to further cracking treatment in heating coil 54.

A furnace 55, within which heating coil 54 is disposed, supplies the required heat to the oil passing through the heating coil to subject it to the desired cracking conditions of elevated temperature and superatmospheric pressure. The resulting highly heated products are directed from heating coil 54 through line 56 and valve 51 into reaction chamber 36 wherein they are separated into vaporous and liquid components which commingle respectively, with the vaporous and liquid components of the products supplied to chamber 36 fromchamber 38 and are subjected therewith to the treatment previously described.

Fractionated vapors of the desired end-boiling point are removed, together with normally gaseous products of the cracking operations, from the upper portion of fractionator 42 and directed through line 58 and valve 59 to'condensation and cooling in condenser 50. The resulting distillate and uncondensed normally gaseous products' are directed from condenser 50 through line GI and valve 52 to collection and separation in receiver 53. The gases may be released from receiver 53 through line 54 and valve 65. Distillate collected in receiver 63 may be recovered therefrom and supplied through line 56 and valve 51 to storage or to any desired further treatment.

When desired, regulated quantities of the distillate collected in receiver 63 may be recirculated by well known means, not illustrated, to the upper portion of tractionator 42 to serve therein as a cooling and refluxing medium.

The preferred ranges of the operating conditions which may be employed in an apparatus, such as illustrated'and above described, to accomplish the desired results, are approximately as follows: Fractional distillation of the charging stock may be accomplished at any desired pressure ranging from substantially atmospheric to 150 pounds, or more, per square inch, superatmospheric pressure. The temperature employed for distillation of the charging stock will, of course, vary, depending upon the boiling characteristics of the same, the pressure employed in the distilling column and the desired separation in this zone. When gasoline-containing crudes are employed, the temperature to which the charging stock is heated to effect its distillation will normally range from 300 to 700 F., or thereabouts, when substantially atmospheric pressure is employed; a correspondingly higher temperature being used with superatmospheric pressures. Higher distilling temperatures may also be employed, when desired, if the charging stock does not contain valuable fractions such as lubricating stock or asphaltic residue, for example, to which the higher .temperatures would be detrimental.

The temperature employed at the. outlet of the light oil cracking or reforming coil may range, for example, from 900 to 1100 F., or thereabouts, and preferably a superatmospheric pressure of the order of 300 to 1000 pounds, or thereabouts, per square inch, is employed at this point in the system. Preferably, the proportionate quantities of relatively hot and relatively cold oils supplied to the first reaction chamber and their respective temperatures are so controlled that a mild cracking temperature of the order of 780 to 900 F., or thereabouts, is maintained therein, and this zone, as previously mentioned, may be operated at substantially the same or lower pressure than that employed at the outlet of the light oil cracking or reforming coil. I

The temperature employed at the outlet of the cracking coil to which the reflux condensate from the fractionator of the system is supplied, is preferably of the order of 900 to 1000 F. with a superatmospheric pressure at this point in the system of from 150 to 500 pounds, or more, per square inch. Preferably, the second reaction chamber is maintained at a higher temperature than that employed in the first reaction chamber and may range, for example, from 850 to 950 F.

The two reaction chambers may be operated at substantially the same pressure or a reduced superatmospheric pressure may be utilized in the second reaction chamber.

The vaporizing or coking zone is preferably operated at a substantially reduced pressure relative to that employed in the second reaction chamber and substantially the same or somewhat lower pressures may be employed in the succeeding fractionating, condensing and collecting equipment.

As an example of one specific operation of the process, conducted in an apparatus such as illustrated and above described: The charging stock is a mixture of crudes containing approximately 50% by volume ofsmackover crude having a gravity of approximately 18.4 A. P. I. and about 50% by volume of a 50.6 A. P. I. gravity Montana crude. The latter contains approximately 15% of good antiknock, light gasoline fractions boiling up to approximately 267 F. and approximately of material boiling up to 410 F. The Smackover crude has an initial boiling point of 300 F. and contains approximately 20% of material boiling up to 577 F. This mixture is supplied to the distilling and fractionating column at a temperature of approximately 670 F. at substantially atmospheric pressure. Approximately 7.5% by weight of the mixed crude charging stock is recovered as light gasoline fractions from the distilling operation and approximately 63% by volume of the mixture, comprising its intermediate fractions boiling up to approximately 585 F., is supplied to the light oil cracking coil wherein this material is heated to an outlet conversion temperature of approximately 1000" F. at a superatmospheric pressure of about 650 pounds per square inch. The remainder of the charging stock, comprising its high-boiling fractions, is commingled with the highly heatedproducts discharged from the light-oil cracking coil and the commingled materials are introduced into the first reaction chamber, which is operated at a superatmospheric pressure of approximately 350 pounds per square inch. The temperature of the mixture of vaporous and liquid conversion products removed from the first reaction chamber is approximately 825 F. The cracking coil to which reflux condensate from the fractionator of the cracking system is supplied, is operated with an outlet temperature of approximately 950 F., the pressure at this point in the system being approximately 250 pounds per square inch, superatmospheric. Substantially the same pressure is maintained in the second reaction chamber and the temperature in the lower portion of this zone is approximately 890 F. Vaporous products are withdrawn from the upper portion of the second reaction chamber and introduced into the reduced pressure vaporizing and separating chamber, while liquid conversion products are separately removed from the secondary reaction chamber and also supplied to the vaporizing and separating chamber. The latter zone is operated at a superatmospheric pressure of approximately 60 inch and the heavy liquid products remaining unvaporized therein are removed from the lower portion of this zone as a final residual liquid product. Vaporous products, after being subjected to rough fractionation in the upper portion of the vaporizing and separating chamber, by means of a suitable refluxing medium introduced to chamber 39 through line 68 and valve 69, to substantially free the same 01 high-boiling liquid particles, are fractionated to form the reflux condensate which is returned to the second mentioned heating coil and the fractionated vapors are condensed to recover a gasoline of approximately 400 F. end-boiling point. The fractionating, condensing and collecting portions oi. the cracking system are operated at substantially the same pressure as that employed in the vaupper portion of the vaporizing and'separating chamber as a means of partially cooling the vaporous products therein and separating the undesirable highboiling components therefrom, prior to their introduction into the fractionator wherein said reflux condensate is formed.

The above described operation will yield per barrel of charging stock, approximately 60% of a mixture of straight-run, cracked and reformed gasoline having an antiknock value 01 approximately 70 by the motor method and approximately 30% of good quality liquid residue suitable as fuel oil, the remainder being chargeable principally to normally gaseous products.

I claim as my invention:

1. A process for the conversion of hydrocarbon oils which comprises fractionally distilling a gasoline-containing charging stock of relatively wide boiling range, separately removing from the fractional distilling step selected lowboiling components of the charging stock, containing materials of poor antiknock value which range of gasoline, and a higher liquid fraction, heating said selected low-boiling fractions to conversion conditions of high cracking temperature and substantial superatmospheric pressure regulated to materially improve the antiknock value of said poor antiknock gasoline fractions and produce submospheric pressure, separately removing selected higher boiling fractions of the charging stock from the fractional distilling step and directly described,

substantial superatmospheric pressure in a separate heating coil, supplying the resulting heated products from said separate heating coil to said second reaction chamber, separating vaporous and liquid component of the materials supplied to said second reaction chamber therein and subjecting said vaporous components to an appreciably longer continued cracking time in this zone than that aflorded said liquid components, removing the latter from said second reaction chamber and appreciably further vaporizing the same in a zone of substantially reduced pressure, separately removing said vaporous components trom the second reaction chamber and fractionating the same in commingled state with vapors evolved in said zone 0! substantially reduced pressure to condense components or the commlngied vapors boiling above the range of gasoline as said reflux condensate which is supplied to the second mentioned heating coil. subjecting fractionated vapots of the desired end-boiling point from the last described iractionating step to condensation, and recovering the resulting distillate.

CHARLES H. ANGEIL.

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