US2130436A - Conversion of hydrocarbon oils - Google Patents

Description

Sept 20, 1938. K. swARTwooD I CONVERSION 0F HYDROCARBON OILS Filed Dec. 24, 1934 NN ZDJOU INVENTOR KENNETH S D O m Y E W. T m

Patented Sept. 20, 1938 UNITED STATES CONVERSION OF HYDROCARBON OILS Kenneth Swartwood, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application December 24, 1934, Serial No. 758,996

14 Claims.

This invention particularly refers to an improved process for the pyrolytic conversion of hydrocarbon oils accompanied by reduction of the residual liquid conversion products of the process to substantially dry coke at relatively high temperature wherein the vaporous products resulting from said conversion and the vaporous products resulting from the coking operation are commingled and subjected to continued conversion without additional heating for the purpose of materially improving the yield and quality of the nal motor fuel product of the process.

A recent development in the coking of relatively heavy oils, such as, for example, residual liquids resulting from the conversion of lower boiling oils, which promises to merit wide adoption in the petroleum industry comprises subjecting the oil in a heating coil to a conversion temperature of the order of 950 to 1000 F., or at least sufficiently high to effect its subsequent reduction to coke, without allowing it suiiicient time in the heating coil to permit the excessive formation and deposition of coke therein. Actual reduction of the highly heated residual oil to coke is usually accomplished in an enlarged coking chamber following the heating coil which may be operated at any desired pressure ranging from substantially atmospheric to a superatmospheric pressure of the order of several hundred pounds 30 per square inch. Operations of this character normally produce a coke of more uniform quality and lower volatility than is obtained by coking methods previously in vogue, due to the relatively high temperature to which the oil to be 35 coked is heated as well as to the fact that the entire mass of material to be coked receives substantially uniform heat treatment. It is alsobelieved that the use of relatively high superatmospheric pressures in the coking zone, which favor reduction of the residual liquids to coke by cracking, help to produce a coke of better and more uniform quality. Heretofore, one of the chief disadvantages in this method of coking has been the high temperature of the vaporous products evolved during the coking operation which necessitates large fractionating and/ or other cooling equipment.

The present invention employs the method of coking above outlined for the reduction of the residual liquid products of the cracking operation to coke and in addition utilizes to advantage the excess heat contained in the vaporous products from the coking operation by commingling the same with the vaporous products resulting from the cracking operation and previously separated from said residual liquids subjected to coking, the commingled vaporous products being sub-- jected to continued conversion in a reaction chamber maintained at substantial superatmospheric pressure without additional heating. y

In one specific embodiment, the invention comprises subjecting hydrocarbon oil to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, separating the resulting vaporous and residual liquid conversion products, heating said residual liquid in a heating coil to a temperature sufliciently high toeffect its subsequent reduction to coke without allowing it suflicient time in the heating coil to permit any excessive formation and deposition of coke in this zone, introducing the highly heated. residual liquid intoa coking chamber maintained at substantial superatmospheric pressure wherein it is reduced to coke, commingling the hot vaporous products from the coking chamber with said vaporous conversion products, subjecting the commingled materials to continued conversion in a separate reaction chamber maintained at substantial superatmospheric pressure, separating the resulting vaporous and liquid conversion products, subjecting the latter to further vaporization at substantially reduced pressure, returning the resulting residual liquid to the heating coil of the coking system, subjecting the vaporous products of the process, including those evolved by said further vaporization, to fractionation whereby their insufficiently converted components are condensed as reflux condensate, returning the reflux condensate to the ilrst mentioned heating coil for further conversion, subjecting fractionated vapors of the desired endboiling point to condensation and collecting and separating the resulting distillate and gas.

Charging stock of any desired type may be employed and, depending upon its characteristics, may be supplied direct to the heating coil of the cracking system, to the heating coil of the coking system, to the fractionator or to the Vaporizing chamber following the last mentioned reaction chamber of the system.

The accompanying diagrammatic drawing i1- lustrates one form of apparatus for carrying out the invention. Referring to the drawing, heating coil l is located Within a furnace 2 of any suitable form and the oil supplied thereto for conversion, in the manner to be later more fully described, is subjected by means of heat suppliedfrom the furnace tothe desired conversion temperature, preferably at a substantial superatmospheric pressure; the heated products being discharged from the heating coil through line 3 and valve 4 into reaction chamber 5.

Reaction chamber 5 is also preferably maintained at a substantial superatmospheric pressure and, although not indicated in the drawing, is preferably insulated to prevent the excessive loss of heat therefrom by radiation so that continued conversion of the heated products supplied to this zone, and particularly their vaporous components, is accomplished therein. In the particular case here illustrated, the stream of hot conversion products from heating coil I -is introduced into the lower portion of chamber 5 wherein vaporous and liquid conversion products separate; the vaporous products passi-ng upward through the chamber to be directed therefrom through line 6 and valve 'I to reaction chamber 8, while the residual liquid conversion products are withdrawn from the lower portion of chamber 5 through line 9 and valve I0 to pump II, byV

means of which they are supplied through line I2, valve I3 and line I4 to heating coil I5. It will be understood, of course, that the invention is not limited to the particular flow through the` reaction chamber illustrated inthe drawing. For example, the stream of hot conversion products from heating coil I may enter the upper portion of the reaction chamber, in which case both vaporous and liquid conversion products may pass Y downward through the chamber to be separately withdrawn from its lower portion, thus affording the liquid products a somewhat longer continued conversion time in the reaction chamber. Other well known alternative methods of ow through the reaction chamber may be employed within the scope of the present invention although, for

the sake of simplicity, they are not here illustrated. However, such alternatives are not to be considered equivalent in all cases but may be selected to suit requirements. In any event, the vaporous and liquid products resulting from conversion in heating coil I and reaction chamber 5 are preferably separated at substantial superatmospheric pressure, the residual liquid prod-y I'I and valve I8, Without allowing the oil suffi-l cient time in heating coil I5 to permit any excessive formation and deposition of coke in this zone and in the line communicating with the coking chamber. Preferably, relatively high rates of heating and relatively high velocities are employed in heating coil I5 to accomplish the desired results. However, this method of coking heavy oils is not new, per se, with the present invention and need not therefore be considered here in any great detail. v Y

Coking chamber I9 is also preferably operated at a substantial superatmospheric pressure which may be substantially the same, somewhat higher or somewhat lower than the pressure employed in reaction chamber '5. Although only one point offintroduction for-the materials to be coked into chamber I9 is illustrated in the drawing it will be understood that they may be supplied thereto at any desired point Aor plurality of points in this zone. Suicient time is afforded the highly cleaning of the chamber.

heated relatively heavy oils supplied to chamber I9 from heating coil I5 to effect their reduction to substantially dry coke in this Zone, the coke being allowed to accumulate within the chamber to be removed therefrom in any well known manner, not illustrated, after the operation of the chamber is completed and preferably after it has been isolated from the rest of the system. Chamber I9 is provided with a suitable drain-line 20 controlled by valve 2I which may also serve, when desired, as a means of introducing steam, water or other suitable cooling medium into the chamber 'after its operation is completed and after it has been isolated from the rest of the system in order to hasten cooling and facilitate It is, of course, also within the scope of the present invention, although only one coking chamber is shown in the drawing, to employ a plurality of such zones, one or more of which may be operated while another or others are beingfcleaned 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.

In accordance with the provisions of the present invention hot vaporous products resulting from the coking operation in chamber Il are withdrawn therefrom through line 22 and valve 23 and arecommingled in line 6 with the vaporous conversion products from reaction chamber 5, the commingled materials entering a separate reaction chamber 8, also preferably maintained at a substantial superatmospheric pressure, wherein they are subjected to continued conversion without additional heating. Chamber 8 is also preferably insulated to minimize loss of heat by radiation, although this is not indicated in the drawing.

In the case here illustrated, the commingled vaporous products from the first reaction chamber and from the vcoking zone enter the upper portion of reaction chamber 8 and are subjected to predetermined continued conversion time as they pass downward through this Zone, the resulting vaporous and liquid conversion products being withdrawn in commingled state from the lower portion of chamber 8 through line 24 and supplied through valve 25 to vaporzing chamber 26.y It is, however, within Ythe scope of the present invention to employ any other desired flow through chamber 8 which will afford the commingled vapors appreciable continued conversion time in this zone and the vaporous and liquid conversion products may, when desired, be separately withdrawn from chamber 8, although such alternative means are not shown in the drawing.

Vaporizing chamber 26, in the case here illustrated, comprises the lower portion of column 21, the upper portion of which comprises fractionator 28, although separate structures may be employed, when desired, for the vaporzing and fractionating zones. Vaporizing chamber 26 is preferably maintained at a substantially reduced pressure relative to that employed in reaction chamber 8 whereby further vaporization of the liquid conversion products supplied to this zone from chamber 8 is accomplished. When vaporous and liquid conversion products are supplied to chamber 26 it also serves as a zone of nal separation for these materials. The residual liquid conversion products remaining unvaporized in chamber 26 are withdrawn therefrom through line 29 and valve 30 to pump 3| by means of which they are fed through line 32 and may be of highly heated products from heating coil I or the residual liquid products from chamber 26 may, when desired, be separately supplied, all or in part, direct to coking chamber I8 at any desired point in this zone by well known means not shown in the drawing or a regulated portion or all of this material may be withdrawn from the system, as one of the final products of the process,

, through line 55 and valve 65 to cooling and stor- 5 pending,

it is returned through line 40, valve 4I and linel 42 to heating coil I, for further conversion, in the manner already described.

Fractionated vapors of the desired end-boiling point are Withdrawn, together with uncondensable gas produced by the process, from the lower portion of fractionator 28 through line 43 and valve 44 and are subjected to condensation and cooling in condenser 45. The resulting distillate and gas passes through line 45 and valve 41 to collection and separation in receiver 48.

Uncondensable gas may be released from the receiver through line 49 and valve 58. Distillate may be Withdrawn from receiver 48 through line 5| and valve 52 to cooling and storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 48 may be recirculated, by well known means, now shown in the drawing, to the upper portion of fractionator 28 to serve as a refluxing :and cooling medium in this zone for assisting fractionation of the vapors and to maintain the desired vapor outlet temperature from the fractionator. f

As previously indicated, the present invention "permits the use of any desired type of hydrocarbon oil charging stock ranging from crude petroleum, topped or reduced crude and the like to heavy residual oils, including all of the various crude oil fractions such as straight-run gasoline, naphtha, kerosene or kerosene distillate, gas oil, fuel oil and the like or mixtures of Such materials as Well asvarious cracked products such as pressure distillate, pressure distillate bottoms, reflux condensates and cracked residual oils. The charging stock is supplied, in the case here illustrated,

through line 53 "and valve 54 to pump 55 by means of which it is fed through line 56 and may be supplied, all or in part, through line 51 and valve 58 into fractionator 28 or through line IEl, line 58 and valve 88 into vaporizing chamber 26 or through line 6I, valve 62 and line I4 to heating coil I5 or from line 6I through line 63, valve 64 and line 42 to heating coil I, the method of supplying the charging stock to the system deprimarily, upon its characteristics.

Preferably., only charging stock of relatively highboiling characteristics is supplied Adirect to heating coil I5 and only charging stock of relatively low-boiling characteristics is supplied direct to heating coil I. Charging Stock of any desired characteristics maybe supplied to the fractionator so long as it contains no appreciable quantity of high-boiling components of a high cokeforming nature unsuitable for conversion in heating coil I and no appreciable quantity of lowboiling fractions within the range of the desired nal motor fuel product of the process but of unsatisfactory quality, particularly with respect to antiknock value, the latter qualication also applying to any charging stock supplied to vaporizing chamber 26, although this is the only limitation with respect to the type of charging stock which may be Supplied to this zone.

The preferred range of operating conditions which may be employed in the practice of the present invention in an apparatus of the general character illustrated and above described may be approximately as follows: The heating coil 'of the cracking system may employ an outlet conversion temperature ranging, for example, from 850 to 1050 F., preferably with a substantial superatmospheric pressure at this point in the system of from 100 to 500 pounds, or more, per square inch. Any desired pressure within substantiallyl the same range but no greater than that employed at the outlet from the heating coil may be utilized in the rst reaction chamber and may be substantially equalized or somewhat reduced in the second reaction chamber. The heating coil of the coking system may employ an outlet conversion temperature ranging, for example, from 900 to 1050o F., preferably with a superatmospheric pressure of from 100 to 500 pounds, or thereabouts, per square inch which pressure may be substantially equalized or somewhat reduced in the succeeding coking chamber. The vaporizing chamber is preferably operated at a substantially reduced pressure relative to that employed inthe last reaction chamber, ranging, for eX ample, from 100 pounds, or thereabouts, per square inch down to substantially atmospheric pressure. The fractionating, condensing and collecting portions of the system may employ pressures substantially the same or somewhat lower than that utilized in the vaporizing chamber.

The following is a specic example of one of the many possible operations of the process of the p-resent invention as it may be accomplished in an apparatus ofthe character illustrated and above described, utilizing as charging stock a Mid-Continent topped crude of about 30 A. P. I. gravity, which is supplied to thevaporizing chamber: Reflux condensate from the fractionator of the cracking system, including the components of the charging stock vaporized in thevaporizing chamber and subsequently condensed in the fractionator, as. well as the intermediate conversion products of the process which are condensed in the fractionator as reflux condensate, is subjected in the heating coil of the cracking system to an outlet conversion temperature of approximately 950 F. at a. superatmospheric pressure of about 350 pounds per square inch. This pressure is substantially equalized in the succeeding.

reaction chamber. Theresidual liquid conversion products from the first reaction chamber are quickly heated 'in a'separate heating coil, together with residual liquid from the vaporizing chamber (the latter including 'some highboiling components of the charging. stock remaining unvaporized in this zone) to ,an outlet temperature of approximately 1000o F. at a superatmospheric pressure of about 250 pounds per square inch. Substantially the same pressure is maintained in the coking chamber and in the second reaction chamber, to which vaporous products from the coking chamber and from the first mentioned reaction chamber are supplied for further conversion. The vaporizing chamber is operated at a superatmospheric pressure of approximately 30 pounds per square inch. This pressure is substantially equalized in the succeeding fractionating, condensing and collecting portions of the system. This operation may produce, per barrel of charging stock, approximately 68 per cent of motor fuel having an antiknock value equivalent to an octane number of approximately 70 by the motor method and approximately 75 pounds of low volatile coke of substantially uniform quality, the remainder being chargeable, principally, to uncondensable gas and loss.

I claim as my invention:

1. In a process for the conversion of hydrocarbon oil wherein the oil is subjected to cracking conditions of elevated temperature and superatmospheric pressure, the resulting vaporous and liquid conversion products separated and the latter subsequently subjected to coking at a ternperature of from 900 to 1050 F. and under substantial superatrnospheric pressure of from 100 to 500 pounds per square inch, the improvement which comprises commingling the vaporous products from the coking operation with the vaporous products previously separated from the liquid conversion products subjected to said coking and subjecting the commingled vapors, yin a zone maintained at conversion temperature, to continued cracking at substantial superatmospheric pressure for a predetermined time without additional heating.

2. In a process for the conversion of hydrocarbon oil wherein the oil is subjected to cracking conditions of elevated temperature and superatmospheric pressure, the resulting vaporous and liquid conversion products separated, the latter subjected to additional heating and coking at a temperature of from 900 to 1050 F. and under substantial superatmospheric pressure of from 100 to 500 pounds per square inch, the improvement which comprises commingling the vaporous products from the coking operation with the vaporous products previously separated from the liquid conversion products subjected to said coking and subjecting the commingled vapors, in a zone maintained at conversion temperature, to continued cracking at substantial superatmospheric pressure for a predetermined time without additional heating.

3. In a process for the conversion of hydrocarbon oils wherein an oil is subjected to cracking conditions of elevated temperature and superatmospheric pressure, the resulting vaporous and liquid conversion products separated and the latter subsequently subjected to coking at high temperature of from 900 to 1050 F. and substantial superatmospheric pressure of from 100 to 500 pounds per square inch, the improvement which comprises comrningling the vaporous products from the coking operation with the vaporous products previously separated from the liquid conversion products subjected to said coking, subjecting the commingled vapors, in a zone maintained at conversion temperature, to continued cracking at substantial superatmosphcric pressure, wherein vaporous and liquid conver-` sion products separate and wherein the vapors are subjected to continued conversion time, thev improvement which -v comprises withdrawing residual liquid conversion products from the reaction chamber, heating the same in a separate heating coil to a temperature suiliciently high to effect their subsequent reduction to coke Without allowing them suicient time in the heating coil to permit the excessive formation and deposition of coke in this zone, introducing the highly heated residual liquid into a coking chamber, maintaining said separate'coil and coking chamber under substantial superatmospheric pressure of from 100 to 500 pounds per square'l inch, reducing the heated residual products to coke in the coking chamber, withdrawing hot vaporous products from the cokingchamber, cominingling the same with the vaporous conversion products from the reaction chamber and subjecting the commingled vapors to continued cracking at substantial superatmospheric pressure in a separate unheated reaction chamber maintained at conversion temperature by the heat of the vaporous products, separating the resulting vaporous and liquid conversion products, sub-" jecting the vapors'to fractionation, whereby their insuiciently converted components are condensed as reiiux condensate, returning the reiiux condensate to the first mentioned heating coil for further conversion, subjecting fractionated vapors of the desired end-boiling point to condensation and collecting the resulting distillate.

5.V In a process for the conversion of hydrocarbon oils wherein an oil is subjected to cracking conditions of elevated temperature and superatmospheric pressure in a heating coil, the heated products introduced into an' enlarged reaction chamber, also maintained at' superatmospherlc pressure, wherein vaporous and liquid conversion products separate and the vapors are sub-` jected to continued conversion time, the improvement which comprises withdrawing residual liquid conversion products from the reaction chamber, heating the same in a separate heating coil' to a temperature suiiiciently high to eiect their subsequent reduction to coke without allowing them suflicient time in the heating coil to permit the excessive formation and deposition of coke in this zone, introducing the highly heated residual liquid in'toll a coking? chamber, maintaining said separate coil and coking chamber undersubstantial superatmospheric pressure of from 100 to 500 pounds per square inch, reducing the heated residual products to coke in the coking chamber, withdrawing hot vaporous products from the coking chamber, commingling the same with the vaporous conversion products from the reaction chamber and subjecting the commingled vapors to continued cracking at substantial superatmospheric pressure in a separate unheated reaction chamber -maintained at conversion temperature by the heat of the vaporous products, separating the resulting vaporous and liquid conversion products, subjecting the latter to further vaporization at substantially reduced pressure, subjecting the vaporous conversion products, including 5 wherein residual liquid resulting from said further vaporization of the liquid conversion products from the last mentioned reaction chamber are returned to the heating coil of the coking system.

8. A process of the character defined in claim 5 wherein hydrocarbon oil charging stock for the process is supplied to the iirst mentioned heating coil.

9. A process of the character defined in claim 5 wherein hydrocarbon oil charging stock for the process, comprising an oil of relatively highboiling characteristics, is supplied to the heating coil of the coking system.

10. A process of the character dened in claim 5 wherein hydrocarbon oil charging stock for the process is supplied to the vaporizing chamber.

1l. A process of the character defined in claim 5 wherein hydrocarbon oil charging stock for the process is supplied to the fractionating zone.

12. A conversion process which comprises subjecting hydrocarbon oil to cracking conditions of temperature and pressure in a cracking zone, separately removing vapors and unvaporized oil from said Zone, heating and coking the unvap-orized oil at temperatures of from 900 to 1050 F. and under pressures of from to 500 pounds per square inch, combining vapors evolved by such heating and coking of the unvaporized oil with vapors removed from the cracking zone, subjecting the commingled vapors., in a Zone maintained at conversion temperature to continued cracking under superatmospheric pressure by the heat contained in the vapors and without additional heating thereof, and fractionating and condensing the vaporous products of said continued conversion.

13. A conversion process which comprises subjecting hydrocarbon oil to cracking conditions of temperature and pressure in a cracking zone, separately removing vapors and unvaporized oil from said zone, passing the unvaporized oil through a heating coil and heating the same therein to a temperature of from 900 to l050 F., discharging the thus heated oil into a coking zone and distilling the same to coke therein, maintaining said coil and coking zone under pressure of from 100 to 500 pounds per square inch, combining the vapors evolved in the coking Zone with those removed from the cracking zone, subjecting the commingled vapors, in a zone maintained at conversion temperature to continued cracking under superatmospheric pressure by the heat contained in the vapors and without additional heating thereof, and fractionating and condensing the vaporous products of said continued conversion.

14. A process for cracking hydrocarbon oil which comprises passing the oil through a heating zone and heating the same therein sufciently to vaporize a substantial portion thereof, introducing the heated oil into an enlarged separating zone and therein separating the same into vapors and liquid, removing the liquid from the separating zone and cracking the same at a temperature of from 900 to 1050 F. under a pressure of from 100 to 500 pounds per square inch, introducing resultant cracked vapors and the rst-named vapors to an unheated reaction zone maintained at cracking temperature by the heat of the vapors, subjecting the commingled vapors to cracking under superatmospheric pressure in the reaction zone by the heat contained in the vapors and without additional heating thereof, and then removing the vapors from the reaction zone and subjecting the same to fractionation and condensation.

KENNETH SWARTWOOD.

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