US2088987A

US2088987A - Conversion of hydrocarbon oils

Info

Publication number: US2088987A
Application number: US732599A
Authority: US
Inventors: Charles H Angell
Original assignee: Universal Oil Products Co
Current assignee: Universal Oil Products Co
Priority date: 1934-06-27
Filing date: 1934-06-27
Publication date: 1937-08-03
Anticipated expiration: 1954-08-03

Description

Aug. 3, 1937. c H ANGELL 2,088,987

' CONVERSION OF HYDROCARBON OILS Filed June 27, 1934 FRACTIONATOR INVENTOVR CHARLES H. ANGELL BY L QRNEY Patented Aug. 3, 1937 PAT NT OFFICE,

, 2,088,987, i 'coNvERsIo or HYDROCARBON OILS Charles H. Angell, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111;, a

corporation of Delaware Application June 27, 1934, Serial No. 732,599

2 Claims. (01. 196-49) 5 invention particularly refers to an improved process for the p-yrolytic conversion of hydrocarbon Ioilsu'a'ccompanied by reduction of the residual liquid conversion products to coke and providesfor separation of the hydrocarbon oil charging stockforthe process, preferably comprising an oil of relatively wide boiling range, into"relativelyloW-boiling and high-boiling components, the latter being subjected to coking tom gether with residual liquid conversion products of the process while all or'selected fractions of its low-boiling components are subjected to conversion, together with'intermediate products of the cracking and i coking operations.

I have previously disclosed a cracking process wherein the hydrocarbon oilcharging stock for thecoperation may beintroduced into an intermediate point-in the" system whereby the charging stock or the products resulting from its relatively mild conversion 9 are separated into relatively low-boiling" and high-boiling. components, the latter-being commingled with the residual liquid conversion products of the process and subjected therewith to further treatment 05 (including: coking, whendesired) while the total or selected fractions" of said low-boiling components are returned to further conversion :within thesystem, together with intermediate products of the cracking and coking operation. The present invention differs from the previous disclosure primarily, in that the present case provides for effecting appreciable further vaporization of the liquid conversion products, under substantially reduced pressure relative to that at which they 35 are formed, :souas "to recover therefrom desirable relatively low-boiling components for fur ther conversion. within the system, without first" subjecting" the same: to the high temperature conditions necessary 'to'accom'plish coking of their higher boiling n'on -Vaporous com ponents."xThe' present invention further differs from the previous disclosure in that the present case is directed exclusively to coking of the non-vaporous residual liquid resulting 5 from" the above d'e'scribedfurther vaporization of the liquid conversion products of the process and,ialso, intl'ie present invention, means are af forded for utilizing regulated quantities of the charging stock for-cooling hot vaporous prod.-

50 ucts ofthe coking operation sufficiently to remove therefrom, prior to' their fractionation for the formation of reflux condensate, heavycomponents" undesirable as cracking stock, including entrained particles of tar, pitch and similar 55 high" coke-forming materials, saidhigh-boiling components being commingled, with the nonvaporous residual liquid and the high-boiling components of the charging stock and subjected to coking therewith.

The provisions of the present invention for separationof the charging stock, prior to any appreciable conversion thereof, into relatively low-boiling and high-boiling components to be subjected to separate treatment, as above described, make it practically advantageous for the treatment of hydrocarbon oil charging stocks of relatively wide boiling range, such as crude petroleum, topped crude and the like, which contain an appreciable quantity of relatively lowboiling fractions suitable as cracking stock as well as high-boiling fractions of a relatively high coke-formihgnature which are not suitable for conversion with its lower boiling components. 1

The charging stock-for the operation of the present process may also include, when desired, oils containing an appreciable quantity of lowboiling fractions within the boiling range of motor fuel, particularly in case such low-boiling fractions possess satisfactory motor fuel characteristics, such asgood anti-knock value, etc'., since, by use of the features of the present invention, such desirable low-boiling components of the charging stock may be removed without being subjected to conversion.

One specific embodiment of the present invention may comprise subjecting hydrocarbon oil recovered fromwithin the system to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, withdrawing both vaporous and liquid conversion products from the reaction chamber, introducing the same into a reduced pressure vaporizing chamber and commingling therewith hydrocarbon oil charging stock for the process, comprising an oil of relatively wide boiling range, in which vaporizing chamber further vaporization of the liquid conversion products and appreciable vaporization of the charging stock is accomplished, whereby lowboiling and high-boiling components of the charging stock areseparated, withdrawing vaporous products from the vaporizing chamber and subjecting the same to fractionation whereby their components boiling above the range of the desired final light distillate product of the process are condensed as reflux condensate, supplying the, reflux condensate comprising the afore-mentioned hydrocarbon oil recovered from within the system, to the heating coil for conversion, subjecting. fractionated vapors of the desired end-boiling point to condensation, recovering the resulting distillate, withdrawing residual liquid remaining unvaporized in said vaporizing chamber therefrom, subjecting the same to heating in a separate heating coil whereby it is quickly brought to a temperature sufficient to effect its subsequent reduction to coke without allowing sufiicient time in the heating coil to permit the appreciable formation and deposition of coke therein, introducing the resulting highly heated residual liquid into a low-pressure coking zone wherein it is reduced to coke and introducing the volatilized materials from the coking zone into said vaporizing chamber.

Several methods of supplying the charging stock to the system, which will be later more fully described, are within the scope of the present invention. In all cases, however, the charging stock is eventually introduced into the vaporizing chamber, prior to any appreciable conversion thereof, wherein it comes into direct contact with heated products from the reaction chamber and hot vaporous products from the coking zone and is thereby subjected to appreciable vaporization, its high-boiling non-vaporous components commingling with the heavy residual liquid conversion products of the process and being subjected to subsequent coking therewith while its vaporized lower boiling components pass, together with vaporous products of the cracking and coking operations, to the fractionator of the system wherein at least a portion of said low-boiling components of the charging stock are condensed to form a portion 'l of said reflux condensate which is subjected to conversion.

It is desired to clearly distinguish this method of operation from similar combination cracking and coking processes wherein the charging stock is supplied to the fractionator of the system or to the cracking coil or to the heating coil of the coking system. With charging stock supplied to the fractionator its total components boiling above the'range of the desired final light distillate product of the'process will be condensed with the reflux condensate formed in this zone and returned therewith to the heating coil of the cracking system. This is not desirable in case the: charging stock contains high-boiling components of a high coke-forming nature which are unsuitable for conversion in the heating coil together with the lower boiling oils. The same applies when the charging stock is fed direct to the heating coil of the cracking system. This method of operation (supplying the charging stock to the fractionator or direct to the cracking coil) is therefore applicable only to charging stocks which contain no appreciable quantity of heavy components of a high coke-forming nature. On the other hand the method of operation wherein the total charging stock is supplied to the heating coil of the coking system is applicable only to charging stocks of a relatively high-boiling nature since it has been found undesirable in coking operations of this character to pass a mixture of relatively low-boiling and high-boiling oils through the heating coil of the coking system, as this ordinarily results in excessive vaporization and coke formation in the heating coil. Aside from the low-boiling components of the charging stock serving no useful purpose and in many cases being detrimental when subjected to heating with the residual liquid conversion products and high-boiling components of the charging stock subjected to coking, the low-boiling oils tend to overload the coking system and they are not subjected by this method of treatment to suitable conversion conditions for the production of high yields of the desired light distillate product. While the methods and means provided by the present invention for supplying a hydrocarbon oil charging stock to the system are particularly desirable for the treatment of charging stocks of relatively wide boiling range, the invention is not limited to the use of such oils since there is no disadvantage in supplying either low-boiling or high boiling charging stock to the vaporizing chamber and several of the specific methods for introducing charging stock to the system provided by the present invention are advantageous regardless of the characteristics of the charging stock since it serves as a cooling medium for the hot conversion products from the reaction chamber or the hot vaporous products of the coking operation, or both, to assist in preventing their excessive further conversion and to assist in effecting separation of residual liquid products, suitable for coking, from the vaporous components of the products from the cracking and coking operation, including desirable low-boiling distillates and intermediate products suitable for further conversion within the system.

The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the features of the present invention including several alternative methods of supplying the: charging stock to the system. These alternative methods are not to be considered equivalent but may be selected to suit the par-' ticular requirements of the oil undergoing treatment and the other operating conditions of the process. It will be further understood that the invention is not limited to the specific form of apparatus illustrated and described. Referring to the drawing, reflux condensate from thefractionator of the system, including selected fractions of the charging stock, is supplied, as will be later described, to heating coil I wherein it is brought to the desired conversion temperature, preferably at a substantial superatmospheric pressure, by means of heat supplied from a furnace 2 of any suitable form. The heated oil is discharged from the heating coil through line 3 and valve 4 into reaction chamber 5.

Chamber 5 is also preferably maintained at a substantial superatmospheric pressure, which may be substantially the same or somewhat lower than that employed at the outlet from the heating coil. Although not indicated in the drawing, the reaction chamber is preferably insulated to prevent the excessive loss of heat therefrom by radiation so that conversion of the heated products supplied to this zone, and particularly their vaporous components, may continue therein. In the case here illustrated, both vaporous and liquid conversion products are withdrawn from the lower portion of chamber 5 through line 6 and valve 1 and are introduced into vaporizing and separating chamber 8. His also within the scope of the present invention, although not illustrated, to separately withdraw vaporous and liquid conversion products from chamber 5, in which case the latter pass from the lower portion of chamber 5, either alone or together with a regulated portion of the vaporous conversion products from this zone, and are directed, as just described, into chamber 8 while the remaining portion or substantially all of the vapors are withdrawn from any desired point or plurality of points-in chamber 5 above the point of removal of the liquid conversionproducts and may bedirected either to chamber 8, entering this zone at any desired pointor plurality of points therein, or may be directed, all or in partgdirect' to fractionator H' by well known means not shown in the drawing.

Chamber 8 is preferably operated at a substantially reduced pressure relative to that employed in chamber 5. Appreciable vaporization of the liquid conversion products supplied to this zone from the reaction chamber and appreciable vaporization of the charging stock, supplied to chamber 8 as will be presently described, is accomplished in this zone. Chambera also serves as a zone of separation for the vaporous products of the cracking and coking operations and the vaporized components of the charging stock from the higher boiling non-vaporous oils supplied to this zone, the latter including residual liquid products of the cracking operation, highboiling components 01 the charging stock unsuitable for conversion in heating coil l and any components, including entrainedtars, pitches and. the like, of a high coke-forming nature in the vaporous products from the coking operation,

supplied to this zone as will be later more fully described. The vaporous products of the cracking and coking operation, exclusive of any high cokeforming components condensed and separated from the lower boiling components of the vapors in chamber 8, and vaporized components of the charging stock are withdrawn from the upper portion of chamber 8 through line 9 and valve I and introduced into fractionator I l.

The components of the vaporous products supplied to fractionator ll boiling above the range of the desired final light distillate product of the process are condensed in this zone as reflux condensate. The reflux condensate is withdrawn from the lower portion of the fractionator through line l2 and valve l3- to pump l4: by means of which it is fed through line l5 and valve Hi to conversion in heating coil l,iin'the' manner already described. Fractionated vapors of the desired end-boiling point are-withdrawn, together with uncondensable gasproduced by the process, from the upper portion of fractionator I I through line I! and valve l8and are subjected to con densation and cooling in'condenser l9. The resulting distillate and gas passes through line and valve 2| to collection and separation in receiver 22. Uncondensable gas may be released from the receiver through'line 23 and valve 24. The distillate may be'withdrawn from receiver 22 through line 25 and valve 26 to storage or to any 1 desired further treatment. When desired, a regulated portion of the distillate collected in receiver 22 may be recirculated. by well known means, not illustrated, to the upper portion of fractionator H to 'serve as a;cooling and reflux-' ing medium to assist fractionation of the vapors.

The liquids remaining unvaporized in chamber 8, including the residual liquid products of the cracking operation, high-boiling'components of the charging stock unsuitable for: conversion in the heating coil of thecracking system and'any high coke-forming'components or materials entrained in the vaporous products from the coking operation,v are withdrawn from the lower portion of this zone through line 21 and .valve 28 to pump 29 byameans of whichthey are fed throughline 30 and valve 3| toh'eating coil 32... Theresidual liquid thus supplied to heating coil 32 is heated to a temperature sufficient to eifect'its subsequent reduction to coke by means of heat supplied to a furnace 33 of any suitableform; Preferably, the heating zone to which the residual liquid to be subjected to coking is supplied is of a .type employing relatively high velocity through the heating coil and relatively high rates of heatinput to the oil passing through the heating coil so that the oil is quicklyheated tothe'desired relatively high temperature without allowing it to remain in the heating coil 'forza sufiicient length of'time to cause any appreciable formation and deposition of coke in the heating .coil and/or in the lines leading from the heating coil to the coking zone. The heated residual liquid is discharged from heating coil 32 through line .34'and is supplied to

coking chambers

35 and 35 by means of lines 36 and 35', respectively,.con-' trolled by the

respective valves

31 and 31. I

Coking chambers 35 and 35' are similar zones wherein reduction of the heated residual oils from heating coil 32 to coke is accomplished and wherein the. coke produced is allowedto' accumulate. It will be understood that one or any desired number of a plurality of coking chambers may be employed and when two or more such zones are utilized they may bev simultaneously operated or, preferably, are alternately operated, cleaned'and prepared for further operation so that the duration of the operating cycle of the process is'not limited by the capacity of the coking zone. The coke may be removed from the chambers in any suitable well known manner, not illustrated, after their operation is completed. Chambers 35 and n 35' are provided with suitable drain-lines 38 and 38', respectively, controlled by the

respective valves

39 and 39 which may also serve, when desired, as a means of introducing suitable cooling material such as, for example, water or steam into the coking chamber after its operation is completed and after it has been isolatedfrom the rest of the system in order to hastencooling and facilitate'cleaning of the chamber.

vaporous products of the coking operation, which usually include some high-boiling compo nents of a high coke-forming nature as well as entrained particles of tars, pitches and the like, are withdrawn from the upper portion of chambers 35 and 35' through the respective lines 40' and 40 controlled by the respective valves 4| and 4| and are directed through line and valve 43 into vaporizing chamber 8 wherein their components of a high coke-forming nature are separatedfrom their lower boiling components, the

former passing with the other residual liquids from chamber 8 to heating coil 32, in the manner previously described, while the latter pass together with the-other vaporous products from chamber 8 to fractionation in fractionator ll.

Hydrocarbon oil charging stock for the process is supplied through line 44 and valve 45 to pump 46 by means of which it is fed through line-4l and may be directed, all or in part, eitherthrough valve 48 in line 41 into reaction chamber 5-or from line 41 through line 49 and valve 58 into line 6 or through line 5| and valve 52 into line 42 or from line 5| through line 53' and valve 54 direct to vaporizing chamber 8. When the charging stock is supplied to reaction chamber it is preferably introduced, as indicated in the drawing, into the lower portion ofthis zone to commingle therewith the conversion products supplied therefrom tovaporizing chamber 8, in the manner already described,

the

serving to cool these products sufiiciently to retardtheir excessive further conversion and to prevent the formation and accumulation of coke in the lower portion of chamber 5 and subsequent 5 portions of the system, prior to the coking stage. It is, however, within the scope of the invention, although not illustrated, to introduce all or a regulated portion of the charging stock into chamber 5 at any other desired point in this zone and when introduced into an intermediate or the upper portion of the reaction chamber the charging stock may be subjected therein to relatively mild conversion conditions, prior to its introduction into the vaporizing chamber, by virtue of the heat imparted thereto from the heated products from heating coil I, with which it is commingled in the reaction chamber, and the con version time afiorded the charging stock in this zone.

When the charging stock is introduced into line 6 it commingles therein with the hot conversion products passing from reaction chamber 5 into vaporizing and separating chamber 8, serving to cool the same and retard their conversion. 25 When the charging stock is supplied to line 6 it is within the scope of the invention to introduce it thereto on either side or on both sides of the pressure reducing valve 1, although only one point of introduction is shown in the drawing. When the charging stock is introduced into line 42 it commingles therein with the hot vaporous products from the coking zone, being thereby heated and subjected to vaporization, and serves as a means of cooling the hot vapor- 3i ous products from the coking zone sufliciently to .retard or arrest their conversion and effect the separation therefrom, in chamber 8', of their high-boiling components which it is desired to return to the coking operation.

40 In any case, Whether the charging stock is sup- .plied direct to the vaporizing chamber or is introduced thereto together with the conversion products from reaction chamber 5 or the vaporous products from the coking operation, it is sub- ,45'jected to appreciable vaporization and is separated thereby, in the vaporizing chamber, into relatively low-boiling and high-boiling components, serving at the same time to assist cooling of the heated products from the reaction cham- 50 her and from the coking zone to insure the separation therefrom of heavy residual liquids.

It will be understood that the charging stock may be supplied to the system in any one or any desired combination of the manners described and 55 it is also within the scope of the invention, when desired, to either preheat the charging stock to below conversion temperature or to cool it to any desired degree in any suitable well known manner, not illustrated, prior to its introduction into 00 chamber 5, line 6, line 42 and chamber 8.

Preferred operating conditions for accomplishing .the process of the invention in an apparatus such as illustrated and above described may be approximately as follows: The conversion tem- 65 perature, measured at the outlet from the cracking coil, may range, for example, from 850 to 950 F., or thereabouts, preferably with a substantially superatmospheric pressure at this point in the system of from 100 to 500 pounds, or there .7 abouts, per square inch. Substantially the same or somewhat lower superatmospheric pressure may be employed in the reaction chamber relative to that employed at the outlet from the cracking coil and the vaporizing and separating chamher is preferably operated at a substantially reduced pressure relative to that employed in the reaction chamber ranging, for example, from 100 pounds, or thereabouts, per square inch down to substantially atmospheric pressure. The residual liquid to be coked may be heated in the heating coil through which it is passed, prior to its introduction into the coking zone, to a temperature of the order of 900 to 1000 F., preferably at a superatmospheric pressure of the order of to 150 pounds per square inch. The coking chambers are preferably operated at substantially atmospheric or relatively low superatmospheric pressure up to 100 pounds, or thereabouts, per square inch and preferably the pressure employed in the coking zone is somewhat higher than that employed in the vaporizing and separating chamber. The fractionating, condensing and collecting portions of the system may employ pressures substantially the same or somewhat lower than the pressure employed in the vaporizing and. separating chamber.

As a'specific example of the operation of the process ofthe present invention as it may be accomplished in an apparatus such as illustrated and above described, with a charging stock comprising a heavy California crude of about 16 A. P. I. gravity, regulated portions of the charging stock are commingled with the conversion products withdrawn from the lower portion of the reaction chamber and with the vaporous products from the coking operation, the commingled materials in both cases being supplied to the vapor izing chamber and the remainder of the charging stock beingsupplied direct to this zone. Approximately 40% of the charging stock is subjected-to coking together with the residual liquid conversion products withdrawn from the vaporizing chamber and the remainder is included with the'reflux condensate from the fractionator of the system supplied to the cracking coil. A v

conversion temperature of approximately 925 F. and a superatmospheric pressure of about 300 pounds per square inch is employed at the outlet from the heating coil with substantially the same pressure in the reaction chamber. The vaporizing chamber is operated at a superatmospheric pressure of about pounds per square inch which is substantially equalized in the succeeding fractionating,.condensing and collecting portions of the system. The residual liquid to be subjected to coking is quickly heated in a separate heating coil to an outlet temperature of approximately 950 F., at a superatmospheric pressure of about 100 pounds per square inch and the heated residue isintroducedinto alternatelyoperatedcoking chambers maintained at a superatmospheric pressure of approximately 50 pounds per square inch. This operation may produce, per barrel of charging stock, approximately 60% of motor fuel having an octane number of approximately 65, approximately 130 pounds of coke which is of good structural strength, uniform quality and has a volatile content of less than 6% and about 650 cubic feet of rich uncondensable gas.

I claim as my invention:

1. A process for the conversion and coking of hydrocarbon oils which comprises subjecting oils recovered from within the system to conversion conditions of elevated temperatures and superatmospheric pressure in a heating coil and com municating reaction chamber, withdrawing vaporous and liquid conversion products from the reaction chamber and introducing them into a reduced'pressure vaporizing chamber, introducing hydrocarbon oil charging stock for the process into the vaporizing chamber for the purpose of cooling the heated products supplied to this zone and for the purpose of subjecting the charging stock to substantial vaporization, withdrawing non-vaporous residual liquid from the vaporizing chamber, rapidly passing the same through a 7 second heating coil and therein heating it sufiiciently to effect its subsequent reduction to coke, introducing the heated residual oil into a lowpressure coking chamber and therein distilling it to coke by the heat imparted thereto in the lastnamed coil, withdrawing the materials volatilized by the coking operation from the coking chamber and introducing the same into the vaporizing 15 chamber, withdrawing vapors from the vaporizing chamber, including vaporous products of the cracking and coking operations remaining uncondensed in the vaporizing chamber and the vaporized low-boiling fractions of the charging stock, 20 subjecting the same to fractionation whereby their components boiling above the range of the desired final light distillate product of the process are condensed as reflux condensate, subjecting fractionated vapors of the desired end-boiling 25 point to condensation, recovering the resulting distillate and supplying the reflux condensate,

comprising said oils recovered from within the system, to the heating coil for said conversion,

the process being further characterized in that 30 regulated quantities of the charging stock are introduced into the lower portion of the reaction chamber to commingle with and cool the conversion products supplied from this zone to the vaporizing chamber.

2. A process for the conversion and coking of hydrocarbon oils which comprises subjecting oils recovered from within the system to conversion conditions of elevated temperatures and superatmospheric pressure in a heating coil and communicating reaction chamber, withdrawing vaporous and liquid conversion products from the reaction chamber and introducing them into a reduced pressure vaporizing chamber, introducing hydrocarbon oil charging stock for the process into the vaporizing chamber for the purpose of cooling the heated products supplied to this zone and for the purpose of subjecting the charging stock to substantial vaporization, withdrawing non-vaporous residual liquid from the vaporizing chamber, rapidly passing the same through a second heating coil and therein heating it sufiiciently to efiect its subsequent reduction to coke, introducing the heated residual oil into a lowpressure coking chamber and therein distilling it tocoke by the heat imparted thereto in the last-named coil, withdrawing the materials volatilized by the coking operation from the coking chamber and introducing the same into the vaporizing chamber, withdrawing vapors from the vaporizing chamber, including vaporous products of the cracking and coking operations remaining uncondensed in the vaporizing chamber and the vaporized low-boiling fractions of the charging stock, subjecting the same to fractionation whereby their components boiling above the range of the desired final light distillate product of the process are condensed as reflux condensate, subjecting fractionated vapors of the desired endboiling point to condensation, recovering the resulting distillate and supplying the reflux condensate, comprising said oils recovered from within the system, to the heating coil for said conversion, the process being further characterized in that regulated quantities of the charging stock are commingled with the stream of hot conversion products passing from the reaction chamber to the vaporizing chamber.

CHARLES H. ANGELL.