US2111401A - Conversion of hydrocarbon oils - Google Patents

Description

March 15, J C MQRRELL CONVERSION. OF HYDROCARBON OILS Filed Jan. 30, 1936 IH PH I l INVENTOR JACQUE C. MORRELL TORNEY Patented Mar. 15, 1938 UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Application" January 30, 1936, Serial No. 61,489

6 Claims.

This invention particularly refers to an improved process for the selective conversion of rel atively low-boiling and high-boiling hydrocarbon oils wherein liquid products resultingfrom conversion of the relatively heavy intermediate liquid conversion products and charging stock as well as, when desired, of the relatively low-boiling intermediate liquid conversion products are subjected to continued heating under independently controlled cracking conditions regulated to eifect their subsequent coking or to materially reduce their viscosity without substantial coke formation.

In one embodiment, the invention comprises subjecting hydrocarbon oil to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil and communieating enlarged reaction chamber, separately withdrawing vaporous and liquid conversion n products from the reaction chamber, passing the latter through a separate heating coil wherein they are quickly heated to a high conversion temperature under non-coking conditions, intro ducing the heated products from said separate heating coil into a separate enlarged chamber wherein their high-boiling components are reduced to coke, subjecting the vaporous conversion products, including those evolved from the materials undergoing coking, to fractionation whereby their components boiling above the range of the desired final light distillate conversion product of the process are condensed as reflux condensate, subjecting fractionated vapors of the desired end-boiling point to condensation, re- 53,; covering the resulting distillate, separating the reflux condensate formed by said fractionation into selected relatively low-boiling and highboiling fractions, returning the latter to the first mentioned heating coil for further conversion, subjecting said selected low-boiling fractions of the reflux condensate to further conversion under independently controlled temperature and pressure conditions in a separate heating-coil, and introducing the resulting heated products into either the reaction chamber or the coking chamber or in part to both.

As an alternative method of operation to that above described, the cracking conditions employed in said separate heating coil to which the liquid conversion products from the reaction chamber are supplied may be regulated to effect a substantial reduction in their viscosity without excessive conversion and without appreciable coking, in which case the enlarged chamber to which the products from this heating coil are supplied functions as a vaporizing and separating chamber from which non-vaporous residual liquid is withdrawn-to cooling and storage or elsewhere, as desired, while the vapors evolved in this zone pass to fractionation together with the other vaporous conversion products of the process.

The features and advantages of the invention as well as various alternative methods of operation of the process will be more apparent with reference to the accompanying diagrammatic drawing and the following description thereof. It will be understood, of course, that the various alternative methods of operation are not to be considered equivalent but may be selected to suit requirements depending primarily upon the type of charging stock employed and the desired re sults. The drawing illustrates one specific form of apparatus embodying the features of the invention and in which the various alternative methods of operation may be accomplished.

Referring to the drawing, hydrocarbon oil charging stock for the process is supplied through line I and valve 2 to pump 3 and, in the particular case here illustrated, is directed through line 4, valve 5 and line B to conversion in heating coil 1 or it may be diverted from line 4 and directed through line 8, valve 9 and line H) to conversion in heating coil ll. When the charging stock comprises an oil of relatively high-boiling characteristics it is preferably supplied to heating coil 1 and, on the other hand, when it comprises an oil of relatively low-boiling characteristics it is preferably supplied to heating coil ll. It is, of course, entirely within the scope of the invention to preheat the charging stock by any well known means, not illustrated, to any desired temperature below that at which its appreciable conversion will occur, prior to its introduction into the system. It is also specifically within the scope of the invention, when desired, and particularly in case the charging stock comprises an oil of relatively wide boiling range, to introduce the same all or in part into fractionator 30, by well known means, not illustrated, wherein it commingles with the vaporous conversion products undergoing fractionation and is separated, together with the reflux condensate formed in this zone, into selected relatively lowboiling and high-boiling fractions which are supplied, respectively, to heating coils II and I, as will be later more fully described.

A furnace l2 of suitable form supplies the required heat to the oil passing through heating coil 'l'to subject the same to the desired conversion temperature, preferably at a substantial superatmospheric pressure, and the heated products are discharged through line 53 and valve it into reaction chamber I5.

Chamber I5 is also preferably maintained at a substantial superatmospheric pressure and, although not indicated in the drawing, this zone is preferably insulated in order to conserve heat so that the heated products supplied to this zone, and more particularly their vaporous components, are subjected to continued conversion therein. vaporous conversion products and nonvaporous residual liquids are separated in chamber i5, the vapors being withdrawn from any desired point or plurality of points in the chamber above the point of removal of the liquid conversion products and in the case here illustrated they are directed through line i6, valve I? and line it into chamber l9. However, when desired, all or regulated portions of the vaporous conversion products thus withdrawn from chamber l5 may be supplied directly to fractionator 30 by well known means, not illustrated.

The non-vaporous liquid conversion products are withdrawn from the lower portion of chamber l5 and are directed through line 20 and valve 2! to further conversion in heating coil 22 which is supplied with the required heat from a suitable furnace 23 and from which the heated products are discharged through line 24 and valve 25 into chamber I9.

As previously mentioned, the invention contemplates two alternative methods of operation with respect to the conditions employed in heating coil 22 and chamber I9. In case it is desired to operate the process for the production of coke as the final residual product of the process the oil passing through heating coil 22 is rapidly heated to a relatively high conversion temperature sufficient to insure its subsequent reduction to coke in chamber IS without allowing it to remain in the heating coil for a sufiicient length of time to permit any appreciable formation and deposition of coke in this zone or in the communicating lines. In case it is desired to operate the process for the production of good quality liquid residue the conversion conditions employed in heating coil 22 are of a relatively mild nature which will effect a substantial reduction in the viscosity of the relatively heavy oil supplied to this zone without excessive conversion and without any appreciable formation of coke.

Chamber I9 is preferably operated at a substantially reduced pressure relative to that employed in chamber I5 in order to assist vaporization of the heated products supplied thereto from heating coil 22. When chamber I9 is operated for the production of coke the coke may be allowed to accumulate within the chamber until it is substantially filled, or until the operation of the chamber has been completed for any other reason, following which it may be removed in any well known manner, not illustrated, and the chamber prepared for further operation. It

is, of course, within the scope of the invention to employ a plurality of such chambers for the deposition of coke in which case they preferably are alternately operated, cleaned and prepared for further operation in order that the coking stage, in common with the rest of the system, may be operated continuously. Line 26 controlled by valve 21 serves as a means of removing non-vaporous liquid residue from chamber l9 when this zone is operated for the production of residual liquid. This line may also serve as 2.

drain-line and, when desired, as a means of introducing steam, water or other suitable cooling material into the chamber, particularly when operated as a coking zone, after operation of the chamber has been completed and after it has been isolated from the rest of the system, in order to hasten cooling and facilitate removal of the coke. Vapors evolved in chamber l9 as well as any vaporous products supplied to this zone from chamber l5 and/or from heating coil II are withdrawn from the upper portion thereof and directed through line 28 and valve 29 to fractionation in fractionator 30 together with any vaporous products supplied directly to the fractionator from chamber i5, as previously mentioned.

The components of the vaporous conversion products supplied to fractionator 30 boiling above the range of the desired final light distillate conversion product of the process are condensed in this zone as reflux condensate and the reflux condensate, together with any charging stock of relatively wide boiling range which may be supplied to the fractionator as previously mentioned, is separated into selected relatively low-boiling and high-boiling fractions. Fractionated vapors of the desired end-boiling point, preferably comprising materials within the boiling range of motor fuel and of good antiknock value, are withdrawn from the upper portion of the fractionator, together with uncondensable gas produced by the operation, and directed through line 3| and valve 32 to condensation and. cooling in condenser 33. The resulting distillate and gas passes through line 34 and valve 35 to collection and separation in receiver 36. Uncondensable gas may be released from the receiver through line 31 and valve 38. Distillate may be withdrawn from the receiver through line 39 and valve 40 to storage or to any desired further treatment. When desired, regulated quantities of the distillate col lected in receiver 35 may be recirculated by well known means, not illustrated in the drawing. into the upper portion of fractionator 30 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 therefrom.

The high-boiling fractions of the reflux condensate formed in fractionator 33 are withdrawn from the lower portion of this zone through line H and valve 42 to pump 43 by means of which they are returned through line 6 and valve 44 to further conversion in heating coil 1.

The selected low-boiling fractions of the reflux condensate formed in fractionator 38 are withdrawn from one or a plurality of suitable intermediate points in this zone, provision being made in the case here illustrated for removing the same from the fractionator through line G5 wherein they are directed through valve 46 to pump dl and are thence supplied through line H] and valve at to further conversion in heating coil II.

The relatively low-boiling oil supplied to heating coil H is subjected therein to the desired conversion temperature by means of heat supplied from a furnace 49 of suitable form. Preferably a substantial superatmospheric pressure is maintained at the outlet from heating coil ll although, when desired, lower pressures down to substantially atmospheric may be employed in his zone. The heated products are discharged from heating coil II through line 50 and may be thence directed, all or in part, through line 5| and valve 52 into reaction chamber l5, wherein they are subjected to continued conversion, to gether with the heated products from heating coil 1, or they may pass, all or in part, through valve 53 in line 50 into chamber l9, entering this zone, in the case here illustrated, through line l8 although they may be introduced thereto at any other desired point or plurality of points in this zone.

The range of operating conditions which may be employed to accomplish the various objects of the invention is approximately as follows:

The heating coil to which the relatively highboiling fractions of the reflux condensate are supplied may utilize an outlet conversion temperature ranging, for example, from 825 to 950 F. preferably with a superatmospheric pressure at this point in the system of from to 500 pounds, or more, per square inch. The heating coil to which the relatively low-boiling fractions of the reflux condensate are supplied may employ an outlet conversion temperature ranging, for example, from 900 to 1050 F. with any deired pressure ranging from substantially atmospheric to a superatmospheric pressure of from 800 pounds, or more, per square inch. Ordinarily temperatures of from 975 to 1050 F. are utilized when relatively low pressures are employed in this zone while relatively high superatmospheric pressures are preferred when milder temperature conditions are employed. The reaction chamber is preferably operated at a substantial superatmospheric pressure which may be substantially the same or somewhat lower than that employed at the outlet from the heating coil to which the relatively high-boiling reflux condensate is supplied. .In case a higher pressure is employed in the reaction chamber than that maintained at the outlet from the heating coil to which the relatively low-boiling reflux condensate is supplied the conversion products from this heating coil are preferably all supplied to the vaporizing or coking chamber. When the process is operated for the production of coke as the final residual product of the process the heating coil to which the residual liquid conversion products from the reaction chamber are supplied preferably employs an outlet conversion temperature of the order of 900 to 1000 F. with any desired pressure ranging from substantially the same as that employed in the reaction chamber down to substantially atmospheric pressure. When the process is operated for the production of liquid residue the heating coil to which the liquid conversion products from the reaction chamber are supplied preferably employs a relatively mild cracking temperature of the order of 760 to 850 F. preferably with a superatmospheric pressure measured at the outlet from this zone of from 100 to 500 pounds, or thereabouts, per square inch. The vaporizing or coking chamber may be operated at any desired pressure ranging from substantially the same as that employed at the outlet from the communicating heating coil down to substantially atmospheric pressure and this zone is preferably maintained at a substantially reduced pressure relative to that employed in the reaction chamber ranging for example, from substantially atmospheric to 150 pounds, or thereabouts, per square inch superatmospheric pressure. 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 coking chamber.

As a specific example of the operating conditions and the results obtainable by one method of operation of the process in an apparatus such as illustrated and above described; the charging stock, which comprises an 18 A. P. I. gravity Mid-Continent straight-run residual oil, is subjected, together with high-boiling fractions of the reflux condensate, to a conversion temperature, measured at the outlet from the heating coil to which this material is sup-plied, of approximately 890 F. with a superatmospheric pressure at this point in the system of about 300 pounds per square inch and substantially the same pressure is employed in the reaction chamber. The relatively low-boiling fractions of the reflux condensate, approximately 90 per cent of which boil within the range of 400 to 600 F., are subjected in a separate heating coil to an outlet conversion temperature of approximately 950 F. at a superatmospheric pressure of about 500 pounds per square inch. About 65 per cent of the heated products from the light oil heating coil are introduced into the reaction chamber and the remainder'are supplied to the lower portion of the coking zone. Vaporous and liquid conversion products are separately withdrawn from the reaction chamber, the vapors being supplied to the coking chamber while the liquid conversion products are quickly heated in a separate heating coil to an outlet conversion temperature of approximately 970 F. at a superatmospheric pressure of about 50 pounds per square inch and the heated products are introduced into the coking chamber, which is maintained at subpounds of petroleum coke of relatively low.

volatility and of good structural strength, the remainder being chargeable, principally to uncondensable gas.

As an illustration of another specific operation of the process; the operating conditions are similar to that above described with the following exceptions: The liquid conversion products from the reaction chamber are subjected in the heating coil to which they are supplied to continued relatively mild conversion at a maximum.

temperature of approximately 810 F. and a superatmospheric pressure of about pounds per square inch, this pressure being substantially equalized in the succeeding vaporizing chamber.

The temperature employed in the heating coil to which the charging stock and relatively heavy fractions of the reflux condensate are supplied is approximately 850 F. and the total heated products from the light oil heating coil are introduced into the reaction chamber. In this operation there is produced, per barrel of charging stock, approximately 56 per cent of 400 F. endpoint motor fuel having an octane number of approximately 66 and approximately 35 per cent of good quality liquid residue meeting market specifications for premium fuel oil, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

1. In a process for the conversion of hydrocarbon 011$,Wh91'911'1 an oil of relatively highi boiling characteristics is subjected to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, vaporous and liquid conversion products separately withdrawn from the reaction chamber and the former subjected to fractionation, the improvement which comprises subjecting said liquid conversion products withdrawn from the reaction chamber to continued conversion under independently controlled heating conditions in a separate heating coil, introducing the resulting heated products into a separate enlarged chamber wherein vaporous and non-vaporous conversion products are separated, subjecting the former to saidfractionation whereby their insufficiently converted com ponents are condensed as reflux condensate and separated into selected relatively low-boiling and high-boiling fractions, subjecting fractionated vapors of the desired end-boiling point to condensation, recovering the resulting distillate, returning said high-boiling fractions of the reflux condensate to the first mentioned heating coil for further conversion, subjecting said low-boiling fractions of the reflux condensate to independently controlled conversion conditions of cracking temperature and superatmospheric pressure in a separate heating coil, and introducing the resulting heated products into said reaction chamber.

2. In a process for the conversion of hydrocarbon oils, wherein an oil of relatively highboiling characteristics is subjected to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, vaporous and liquid conversion products separately withdrawn from the reaction chamber and the former subjected to fractionation, the improvement which comprises subjecting said liquid conversion products withdrawn from the reaction chamber to continued conversion at a relatively mild cracking temperature and substantial superatmospheric pressure in a separate heating coil whereby to materially reduce their viscosity without excessive conversion thereof and without appreciable coke formation, introducing the heated products from said separate heating coil into a vaporizing and separating chamber maintained at a substantially reduced pressure relative to that employed in the reaction chamber, recovering nonvaporous residual liquid from the vaporizing and separating chamber, separately removing the vaporous conversion products therefrom and subjecting the same to said fractionation for the formation of reflux condensate, subjecting fractionated vapors of the desired end-boiling point to condensation, recovering the resulting distillate, separating the reflux condensate formed by said fractionation into selected relatively low boiling and high-boiling fractions, returning said high-boiling fractions to the first mentioned heating coil for further conversion under independently controlled temperature and pressure conditions, subjecting said low-boiling fractions of the reflux condensate to independently controlled conversion conditions of temperature and superatmospheric pressure in a separate heating coil, and introducing at least a portion of the resulting heated products into the reaction chamber.

3. In a process for the conversion of hydrocarbon oils, wherein an oil of relatively highboiling characteristics is subjected to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, vaporous and liquid conversion products separately withdrawn from the reaction chamber and the former subjected to fractionation, the improvement which comprises subjecting said liquid conversion products withdrawn from the reaction chamber to continued conversion at a relatively mild cracking temperature and substantial superatmospheric pressure in a separate heating coil whereby to materially reduce their viscosity without excessive conversion thereof and without appreciable coke formation, introducing the heated products from said separate heating coil into a vaporizing and separating chamber maintained at a substantially reduced pressure relative to that employed in the reaction chamber, recovering non-vaporous residual liquid from the vaporizing and separating chamber, separately removing the vaporous conversion products therefrom and subjecting the same to said fractionation for the formation of reflux condensate, subjecting fractionated vapors of the desired endboiling point to condensation, recovering the resulting distillate, separating the reflux condensate formed by said fractionation into selected relatively low-boiling and high-boiling fractions, returning said high-boiling fractions to the first-mentioned heating coil for further conversion, subjecting said low-boiling fractions to further conversion under independently controlled temperature and pressure conditions in a separate heating coil, and introducing at least a portion of the resulting heated products into the vaporizing and separating chamber.

4. A process such as claimed in claim 2, wherein the remainder of the heated products from the last mentioned heating coil is introduced into the vaporizing and separating chamber.

5. In a process for the conversion of hydrocarbon oils, wherein an oil of relatively highboiling characteristics is subjected to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, vaporous and liquid conversion products separately withdrawn from the reaction chamber and the former subjected to fractionation, the improvement which comprises heating the liquid conversion products withdrawn from the reaction chamber to a relatively high conversion temperature under noncoking conditions in a separate heating coil, introducing the highly heated products into a coking chamber wherein their high-boiling components are reduced to coke, removing vaporous conversion products from the coking chamber, subjecting the same to said fractionation for the formation of reflux condensate, subjecting fractionated vapors of the desired end-boiling point to condensation, recovering the resulting distillate, separating the reflux condensate formed by said fractionation into selected relatively low boiling and high-boiling fractions, returning said high-boiling fractions to the first mentioned heating coil for further conversion, subjecting said low-boiling fractions to further conversion under independently controlled temperature and pressure conditions in a separate heating coil, and introducing at least a portion of the resulting heated products into the reaction chamber.

6. A process such as claimed in claim 5 wherein the remainder of the heated products from the last mentioned heating coil is introduced into the coking chamber.

JACQUE C. MORRELL.

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