US2089668A - Conversion of hydrocarbon oils - Google Patents

Description

DGENCH H0O Aug. 10, 1937. D, SEGUY 2,089,668

CONVERSION OF X-IYDROCARBON OILS Filed Dec. 19, 1932 2 Sheets-Sheet 2 Patented Aug. 10, 1937 oearcn flUL CONVERSION OF HYDROCARBON OILS Jean Delattre Seguy, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application December 19, 1932, Serial No. 647,879

6 Claims.

This invention refers to an improved process and apparatus for the treatment of crude petroleum oils containing appreciable quantities of gasoline or gasoline-fractions of low anti-knock value whereby the gasoline components are separated from the crude, the topped crude, or all but the high-boiling components thereof, is subjected to conversion for the production of additional yields of motor fuel and the motor fuel produced by the topping and cracking operations, comprising a mixture of cracked motor fuel and straight-run gasoline, is separately subjected to more severe conversion conditions such as will effect a material improvement in its anti-knock value without excessively altering its boiling range.

The features of the invention are not limited to use in any specific form of apparatus and with minor changes to existing equipment may be applied to several well known types of cracking plants.

The attached diagrammatic drawings (Figures 1 and 2) illustrate how the features of the invention have been adapted to two well known and widely used types of cracking plants. Figure 1 illustrates a cracking process of the type wherein both vaporous and liquid conversion products are withdrawn in commingled state from a reaction zone maintained at substantial superatmospheric pressure and introduced into a reduced pressure vaporizing and residuum separating zone. Figure 2 illustrates the type of cracking process wherein separation of vaporous and residual conversion products is accomplished in a reaction zone maintained at substantial superatmospheric pressure. The following description of the drawings will serve to more clearly illustrate the adaptability of the process of the present invention and its operation as it may be practiced in the two specific forms of apparatus illustrated.

Referring now to Fig. 1 ofthe drawings, heating coil I, located within a furnace 2 of any suitable form, receives heat therefrom sufficient to bring the oil introduced into the heating coil, and passing therethrough, as will be later more fully described, to the desired conversion temperature, preferably at a substantial superatmospheric pressure. The heated oil is discharged through line 3, valve 4 and line 5 into reaction chamber 6, which is also preferably'maintained at a substantial superatmospheric pressure and which, although not illustrated in the drawings, is preferably well insulated to prevent the excessive loss of heat therefrom by radiation so that conversion of the heated oil from heating coil I,

and more particularly its vaporous components, may continue in this zone. Both vaporous and liquid conversion products are withdrawn from the lower portion of chamber 6 through line 1 and valve 8 and are introduced into vaporizing chamber 9.

Chamber 9 is preferably operated at a substantially reduced pressure relative to that employed in chamber 6, by means of which further vaporization of the liquid conversion products introduced into this zone is accomplished. Vaporous and residual conversion products are separated in chamber 9 and the residual liquid, when such is produced, may be withdrawn therefrom through line I and valve II to cooling and storage or to any desired further treatment. The operating conditions of the process may, when so desired, be so controlled that the residue produced in chamber 9 is substantially dry petroleum coke, in which case the coke may be allowed to accumulate within this zone, to be removed therefrom after the operation of the chamber is completed. Also, in such cases, a plurality of coking chambers may be employed, when desired, although only a single chamber is illustrated in the drawings, and a plurality of such chambers may be simultaneously operated or, preferably, are alternately operated, cleaned and prepared for further operation.

Vaporous products are withdrawn from chamber 9 through line l2 and valve l3 to fractionation in fractionator 14, wherein their insufficiently converted components are condensed as reflux condensate. The reflux condensate collects within the lower portion of fractionator M to be withdrawn therefrom through'line l and valve Hi to pump H, by means of which it is returned through line l8 and valve l9 to further conversion in heating coil l.

Raw oil charging stock, comprising a crude petroleum oil containing an appreciable percentage of gasoline or gasoline fractions, may be supplied through line 20 and valve 2| to pump 22, from which it is fed through line 23 and may pass either through line 24 and valve 25 into chamber 9 or through line 26 and valve 21 into fractionator I 4. When the charging stock contains appreciable high-boiling components, which are not desirable as cracking stock in heating coil I, the raw oil is preferably supplied, as illustrated and described, into chamber 9, wherein all but said undesirable high-boiling components are vaporized and pass to fractionation in fractionator l4 while the high-boiling components remain in chamber 9 to commingle with and form a part of the residual liquid product of the process, when such is produced in this zone, or to be reduced to coke when the process is operated for the production of a solid residual 5 product. When the charging stock does not con tain any appreciable amount of high-boiling materials, undesirable as cracking stock in heating coil I, the raw oil may be supplied, as illustrated and previously described, to fractionator l0 l4, wherein it serves as a cooling and fractionating medium by direct contact with the vaporous products in this zone and wherein all but its gasoline components of the desired end-boiling point are condensed with the reflux condensate to be supplied therewith to heating coil I for conversion, as already described. Regardless of whether the raw oil is supplied to chamber 9 or to fractionator l4 its components, desirable as cracking stock in heating coil I, boiling above the range of the desired motor fuel product, are supplied to this zone, together with the reflux condensate from fractionator l4 and the gasoline components of the charging stock, of the desired end-boiling point, are removed from the upper portion of fractionator 14, together with the motor fuel products of the cracking operation of similar end-boiling point.

The commingled straight-run gasoline derived from the crude oil charging stock and motor fuel products of the cracking operation, of the desired end-boiling point, are withdrawn in vaporous form from the upper portion of fractionator l4, together with uncondensable gases produced by the operation, through line 28 and valve 29 and are subjected to condensation in condenser 30. The resulting distillate and uncondensable gas passes through line 3| and valve 32 to collection in receiver 33. Uncondensable gas may be released from the receiver through line 34 and valve 35. Distillate comprising the final motor fuel product of the process may be withdrawn from the receiver through line 36 and valve 31 to cooling and storage or to any desired further treatment. However, a portion of the distillate collected in receiver 30 is subjected to further treatment (reforming) as will be presently described, for the specific purpose of producing therefrom compounds of better motor fuel characteristics, particularly with respect to their anti-knock value, within the boiling range of the desired final light product of the process, which products are returned through the fractionating and condensing stages of the process to collection in receiver 30, thereby materially improving the motor fuel characteristics and particularly the anti-knock value of the final product withdrawn through line 36 and valve 31.

The distillate to be reformed is withdrawn from receiver 30 through line 38 and valve 39 to pump 40 by means of which it is supplied through line 4| and valve 42 to heating coil 43 wherein it is subjected to the desired conversion conditions preferably more severe than those employed in heating coil I, and preferably at substantial super-atmospheric pressure, .by means of heat supplied from a furnace 44 of any suitable form. The heated oil is discharged from heating coil 43 through line 45 and may pass either through valve 46 in this line and through line 5 into reaction chamber 6, or may be diverted from line 45 through line 41, passing either through valve 48, in this line, into the lower portion of chamber 9 or through line 49, valve 50 and line 6 into the upper po i n of chamber 9 or into this zone at any desired intermediate point, by well known means not illustrated in the drawings.

When it is desired to subject the heated oil from heating coil 43 to continued conversion time at superatmospheric pressure and/or when it is desired to commingle the highly heated oil from heating coil 43 with the less highly heated oil from heating coil l for the purpose of increasing the temperature of the latter, during its continued conversion time in chamber 6, the oil from heating coil 43 preferably passes, as previously described, through line 45 and valve 46 into line 5, commingling therein with the heated oil from heating coil 1 and passing therewith to further conversion time in chamber 6. It will be understood, however, that the oil from heating coil 43 may be introduced at any desired point in chamber 6, although well known means for accomplishing this are not illustrated in the drawings.

When the desired degree of conversion or reforming of the distillate suppled to heating coil 43 is accomplished within the heating coil the heated oil from this zone may be introduced, as previously described, through lines 45, 41 and 49, valve 50 and line 6 into chamber 9, or it may be introduced, by well known means not shown in the drawings, into chamber 9 at any other desired point in this zone. By introducing all or a portion of the heated oil from heating coil 43 through line 45, line 41 and valve 48, as previously described, into the lower portion of chamber 9, means is provided for bringing this highly heated material into direct and intimate contact with the residual material in chamber 9, whereby to assist reduction of the residual material to coke.

Referring now to Figure 2, which illustrates another type of cracking plant also embodying the features of the present invention, heating coil 5| is located in a furnace 52 of any suitable form by means of which the required heat is supplied to the oil passing through this zone to bring it to the desired conversion temperature,

preferably at a substantial superatmospheric pressure. The heated oil is discharged through line 53 and valve 54, into reaction chamber 55, which is also operated at substantial superatmospheric pressure and, although not illustrated in the drawings, is preferably well insulated to prevent the excessive loss of heat by radiation from the products undergoing continued conversion in this zone.

Vaporous and residual conversion products are separated in chamber 55 and the residual liquid, when such is produced, may be withdrawn to cooling and storage or to any desired further treatment through line 56 and valve 51. Operating conditions of the process may be so regulated, when desired, that only substantially dry petroleum coke remains in chamber 55 as the residual product of the process, in which case it may be allowed to accumulate in this zone, to be removed therefrom after the operation of the chamber has been completed. Under such conditions a plurality of coking chambers may be employed, when desired, to provide additional space for the accumulation of the coke and may be operated simultaneously, or preferably, are alternately operated, cleaned and prepared for further operation.

Vaporous conversion products pass from chamber 55 through line 58 and valve 59 to fractionation in fractionator 60, for the purpose of separating theirinsufficiently converted components from the lower boiling desirable light products. The insufliciently converted low-boiling components of the vapors are condensed as reflux condensate in fractionator 60 and withdrawn therefrom through line 6| and valve 62 to pump 63, by means of which they are returned through line 64 and valve 65 to further conversion in heating coil 5 I. V

The crude oil charging stock for the process, containing an appreciable quantity of components within the boiling range of gasoline, are supplied through line 66 and valve 6'! to pump 68 and is fed therefrom through line 68, from which it may pass either through line '10 and valve H into reaction chamber 55,-entering this zone at any desired point, although only one point of introduction is shown in the drawings, or the charging stock may be directed through line 72 and valve 13 into fractionator 60 to which it may also be admitted at any desired point. When the charging stock contains no appreciable amount of high-boiling materials, undesirable as cracking stock in heating coil 5|, it may be supplied to fractionator 60, serving as a cooling and refluxing medium to assist fractionation in this zone, in which case the charging stock comes into direct contact withthe hydrocarbon vapors undergoing fractionation, its low-boiling components within the range of the desired motor fuel product of the process being removed in vaporous form from the upper portion of the fractionator, together with the motor fuel products resulting from conversion, while the higher boiling components of the charging stock commingle with the reflux condensate condensed in fractionator 60, passing therewith, by means already described, to conversion in heating coil 5|. When the charging stock contains an appreciable quantity of high-boiling components undesirable as cracking stock in heating coil 5| the total charging stock is preferably supplied through line 18 and valve II to reaction chamber 55, where it comes into direct contact with the materials from heating coil 5| undergoing conversion in this zone, being thereby subjected to the conversion conditions maintained in the reaction chamber which preferably, are sufficient to effect conversion of said high-boiling components of the charging stock. The residual products resulting from conversion of the charging stock in chamber 55 commingle therein with the other residual conversion products of the process while the total vaporous conversion products from chamber 55, together with any low-boiling components of the raw oil, which may not have undergone appreciable conversion in the reaction chamber, pass therefrom to further treatment, as already described, in fractionator 60.

Straight-run gasoline or gasoline fractions derived from the charging stock are withdrawn in vaporous state from the upper portion of fractionator 60, together with the motor fuel conversion products of similar end-boiling point and uncondensabl-e gas produced by the process, through line 14 and valve 15. The commingled low-boiling materials are subjected to condensation in condenser 16 from which the resulting distillate and gas passes through line H and valve 18 to collection in receiver 19. Uncondensable gas may be released from the receiver through line and valve 8|. Distillate comprising the final motor fuel product of the process is withdrawn from the receiver through line 82 and valve 83 to storage or to any desired further treatment. However, a portion of the distillate collected in re- Search R00 ceiver 19 is subjected to further treatment (reforming) as will be presently described, for the specific purpose of producing therefrom compounds of better motor fuel characteristics, particularly with respect to their anti-knock value, within the boiling range of the desired final light product of the process. These products are returned through the fractionating and condensing stages of the process to collection in receiver 19, thereby materially improving the motor fuel characteristics, and particularly the anti-knock value, of the final product withdrawn through line 82 and valve 83.

The distillate to be reformed is withdrawn from receiver 19 through line 84 and valve 85 to pump 86. by means of which it is supplied through line 81 and valve 88 to heating coil 89. which is located within a furnace 90, of any suitable form, by means of which the distillate is heated, preferably to a higher conversion temperature than that employed in heating coil 5| and preferably at a substantial superatmospheric pressure. The heated oil is discharged from heating coil 89 through line 9| and may pass either through line 82, valve 93 and line 53 into reaction chamber 55 or through line 94 and valve 95 into reaction chamber 55. It will be understood that the heated oil from heating coil 89 may enter chamber 55 at any desired point, either alone or commingled with the heated oil from heating coil 51. although only two points of introduction are shown in the drawings. The feature of intror'ucin" the h hly heated distillate from heating coil 89 into direct contact with the residual marenal in the lower portion of the reaction chamber greatly assists reduction of the residue to substantially dry coke when this type of operation is desired.

Operating conditions utilized in the practice of the process of the present invention are preferably as follows: conversion temperatures ranging from 850 to 975 F., or thereabeu s, and a superatmospheric pretsur-e of from to 500 pounds, or more, per souare inch. are preferred at the outlet from the heatin coil to which th reflux condensate is supplied, A substantial superatmcspheric pressure either substantially equalized with or somewhat reduced rela ve to that employed at the outlet from the heating ee may be utilized n the reaction chamber. The vaporizing chamber, when such is emp oyed. (as illustrated in Fig. 1) is preferably operated at a substantially reduced pressure relat ve to that employed in the reaction chamber ranging, for example, from .100 pounds, or thereabou s. per square inch down to substantially atmospheric pressure. The fractionating, Condensin and collecting portions of the system may utilize p essures substantia ly equalized with or somewhat reduced relative to the pressure in the preced ng portion of the apparatus. Conversion temperatures employed at the outlet from the heatin coil to which the distillate to be reformed is supplied, may range, for example, from 950 to 1fl50 F., preferably with a superatmosnheric pressure at the outlet from this zone of from 300 to 800 pounds, or more, per square inch.

As a specific example of one of the many pos-, sible operations of the process of the present invention, the charging stock is a Michigan crude containing approximately 40% of 400 end-point motor fuel having an exceptionally low antiknock value, equivalent to an octane number of approximately 25. The charging stock is introduced into the reduced pressure vaporizing cham- 55 heating coil and communicating reaction chamber of a system such as illustrated in Fig. 1. Reflux condensate from the fractionator of the cracking system, having a boiling range of approximately 400 to 700 F., is supplied, together with intermediate fractions of the charging stock of corresponding boiling range, to the low temperature heating coil of the system wherein it is subjected to an outlet temperature of approximately 935 F. at a superatmospheric pressure of about 400 pounds per square inch. A portion of the distillate collected in the receiver of the system, including cracked and straight-run motor fuel, is subjected in a separate heating coil to a temperature of approximately 960 F., at a superatmospheric pressure of about 600 pounds per square inch. The heated oils are commingled and introduced into the reaction chamber of the system, which is maintained at a superatmospheric pressure of about 400 pounds per square inch. The vaporizing chamber is operated at a reduced pressure of about 30 pounds per square inch which is substantially equalized in the succeeding fractionating, condensing and collecting portions of the system. This operation may yield per barrel of crude oil charging stock, about 70% of motor fuel having an anti-knock value equivalent to an octane number of approximately '78 and about 18% of good quality residual oil, the remaining 12% or thereabouts, based on the charging stock, being chargeable to uncondensable gas.

By employing a somewhat higher temperature in both heating coils and introducing the heated distillate from the high temperature heating coil into direct contact with the residual material in the vaporizing chamber, whereby it is reduced to coke, a somewhat increased yield of motor fuel of about the same anti-knock value may be produced with a corresponding increase in the yield of gas and the production of about 50 pounds of coke, per barrel of charging stock.

About the same yields may be obtained under similar conditions in an apparatus of the type such as illustrated in Fig. 2, with the exception that the final motor fuel product produced in this appartus will normally be of somewhat lower anti-knock value, the yield of gas somewhat lower and the yield of residue (either liquid or solid) somewhat higher, as compared with the operations above outlined.

I claim as my invention:

1. In a process for the conversion of hydrocaremperature at superatmospheric pressure in a 'on oil wherein the oil is subjected to cracking ber, both vaporous and liquid conversion products withdrawn from the reaction chamber to a reduced pressure vaporizing chamber wherein the vaporous and residual conversion products of the process separate, the vapors subjected to fractionation for the removal of their insufliciently converted components which are condensed as reflux condensate, the reflux condensate returned to the heating coil for further conversion and uncondensed fractionated vapors, within the boiling range of motor fuel, subjected to condensation and the resulting distillate colcomprising petroleum oil containing an appreci able quantity of materials within the boiling range of gasoline, into direct contact with the vaporous conversion products, whereby its gaso- I line components are recovered together with the motor fuel conversion product, and its higher boiling components desirable as cracking stock, are supplied to the heating coil for conversion, together with the reflux condensate, subjecting distillate recovered from the operation, comprising a mixture of straight-run gasoline and motor fuel resulting from cracking, to a more severe cracking temperature at superatmospheric pressure in a separate heating coil and subjecting the heated materials from said separate heating coil to further treatment in the same cracking sys- 2. A process of the character defined in claim 1 wherein heated materials from said separate heating coil are commingled with the vaporous and liquid conversion products passing from the reaction chamber to the reduced pressure vaporizing chamber.

3. A process of the character defined in claim 1 wherein heated materials from said separate heating coil are introduced into direct contact With the residual material in the reduced pressure vaporizing chamber for the purpose of assisting its reduction to coke.

4. A process of the character defined in claim 1 wherein raw oil charging stock for the system is supplied to the reduced pressure vaporizing chamber.

5. A process of the character defined in claim 1 wherein raw oil charging stock for the system is supplied to the fractionator.

6. A combined topping, cracking and reforming process which comprises passing hydrocarbon oil in a restricted stream through a heating zone and heating the same therein to cracking temperature under superatmospheric pressure, subsequently reducing the pressure on the heated oil and separating vapors from residue in a reduced pressure separating zone, introducing crude petroleum containing natural gasoline to said separating zone and vaporizing the gasoline and heavier fractions thereof in this zone, fractionating and condensing the commingled cracked and crude oil vapors to separate fractions thereof heavier than gasoline and to form a condensate comprising a blend of natural gasoline hydrocarbons and cracked gasoline hydrocarbons, supplying such separated fractions heavier than gasoline to said heating zone as said hydrocarbon oil, passing a portion of the I blended natural gasoline hydrocarbons and JEAN DELATTRE SEGUY.

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