US2063114A - Conversion of hydrocarbon oils - Google Patents

Description

Dec. 8, 1936. J. c. MORRELL 2,063,114

CONVERSION OF HYDROCARBON OILS I Filed May 29, 1955 FRACTIONAT'OR FURNACE 29 3| 55 61 RECEIVER SEPARATING AND COLUMN T 26 FURNACE 77 FURNACE INVENTOR JACQUE C. MORRELL Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Application May 29, 1935, Serial No. 24,090

6 Claims.

This invention refers to an improved process for the distillation of hydrocarbon oil accompanied by selective conversion of its relatively low-boiling and high-boiling components as well as selective conversion of relatively low-boiling and high-boiling intermediate conversion products of the process and also accompanied by reduction of the residual liquid conversion products of the process to substantially 'dry coke, wherein vaporous products from the coking operation and vaporous products resulting from said conversion of the intermediate conversion products and high-boiling fractions of the charging stock are subjected to further conversion together with said relatively low-boiling fractions of the charging stock for the production of high yields of desirable light distillate products such as motor fuel of high antiknock value.

In one embodiment, the invention comprises subjecting charging stock for the process, comprising a hydrocarbon oil of relatively wide boiling range, to fractional distillation by indirect heat exchange with hot vaporous conversion products from a heating coil of the system, whereby it is separated into relatively low-boiling and high-boiling fractions, subjecting said low-boiling fractions to conversion in said heating coil, subjecting the high-boiling fractions of the charging stock to conversion conditions of 30 cracking temperature and superatmospheric pressure in a separate heating coil and communicating reaction chamber, withdrawing both vaporous and liquid conversion products from the reaction chamber in commingled state, introducing the same into a coking chamber wherein the residual liquid conversion products are reduced to substantially dry coke, withdrawing vaporous products from the coking chamber, separating therefrom high-boiling components and returning the same to the reaction chamber for further conversion, subjecting the remaining vaporous products from the coking zone to further conversion in the first mentioned heating coil, together with said low-boiling frac- 45 tions of the charging stock, subjecting the conversion products from the first mentioned heating coil, after said heat exchange with the charging stock, to fractionation, whereby their components boiling above the range of the desired final light distillate product of the process are condensed as reflux condensate and separated into selected relatively low-boiling and high-boiling fractions, returning said highboiling fractions of the reflux condensate to con- 55 version together with said high-boiling components of the charging stock, subjecting said low-boiling fractions of the reflux condensate to independently controlled conversion conditions in another separate heating coil and commingling the resulting highly heated products 5 with the conversion products from the heating coil to which said relatively high-boiling oils are supplied.

Several modifications of the specific embodiment of the invention above outlined may be employed without departing from the scope of the present invention. Provision for employing several of such modifications as well as the specific operation above outlined are shown in the accompanying diagrammatic drawing which illustrates one specific form of apparatus embodying the features of the invention. The following description of the drawing will serve to more clearly illustrate the operation 01' the process of the invention as it may be accomplished in the apparatus illustrated. It will be understood, of course, that the various modifications described and illustrated are not to be considered equivalent but that the type of operation may be selected to suit the requirements of the particular oil undergoing treatment in order to obtain the desired results.

Referring to the drawing, hydrocarbon oil charging stock for the process, preferably comprising an oil of relatively wide boiling range, such as, for example, crude petroleum, topped crude or the like, is supplied through line I and valve 2 to pump 3 by means of which it is fed through line 4 and may be directed through line 5, valve 6, heat exchanger 1, line 8 and valve 9 into distilling and fractionating column 10 wherein it is subjected to vaporization and to fractional distillation by means of the heat recovered in heat exchanger 1 from relatively hot conversion products from heating coil I3. Any other suitable means of heating the charging stock may, of course, be employed, when desired, but preferably at least a portion of the heat required for distillation of the charging stock is obtained in the manner illustrated. The charging stock is separated by fractional distillation in column In into selected relatively low-boiling and high-boiling fractions and preferably this operation is accomplished at a substantial superatmospheric pressure sufficient to overcome friction in heating coil l3 and the pressure maintained in this zone so that the overhead stream of fractionated vapors from column In may be supplied to the heating coil and passed through this zone without the aid of a pump or compressor. Provisions are shown in the drawing for supplying the fractionated vapors from column l0 through line H and valve [2 to heating coil l3.

Heating coil I3 is located within a furnace l4 of any suitable form by means of which sufiicient heat is supplied to the oil passing through this zone to subject it to the desired conversion conditions of elevated temperature, preferably at superatmospheric pressure, and the stream of hot conversion products is discharged from the heating coil through line [5 and valve I6 passing, in the case here illustrated, through heat exchanger 1 and thence through line Ill and valve 18 into fractionator 52, wherein their desirable low-boiling components are separated from their higher boiling insufiiciently converted components, as will be later more fully described.

In the case here illustrated, indirect heat exchange between the charging stock and the stream of hot conversion products from heating coil l3 not only serves to supply heat to the, charging stock for its fractional distillation but also serves to cool the conversion products from heating coil i3 sufficiently to prevent any appreciable further conversion thereof and to remove therefrom any undesirable high-boiling polymers and residual materials. The condensate resulting from such partial cooling of the conversion products from heating coil [3 in heat exchanger 1 includes said undesirable high-boiling materials and may be withdrawn from the lower portion of this zone through line H! and valve 29 and introduced into column H] to commingle therein with the charging stock and be subjected therewith to fractional distillation, a major portion of the condensate ordinarily being commingled with the high-boiling fractions of the charging stock in column l0 and subjected therewith to further treatment.

The high-boiling fractions of the charging stock are withdrawn from the lower portion of column I 0, together with any corresponding components of the condensate from heat exchanger 1 through line 2| and valve 22 to pump 23 by means of which this material is fed through line 25 and may be directed, all or in part, through line 26, valve 21, line and valve 10 to conversion in heating coil 28 or through valve 48 in line 25 into line 46 and thence to reaction chamber 32, for further treatment, as will be later more fully described.

A furnace 29 of any suitable form supplies the required heat to the oil passing through heating coil 28 to subject it to the desired conversion conditions of elevated temperature and superatmospheric pressure and the stream of hot conversion products is discharged from heating coil 28 through line 3!} and valve 3! into reaction chamber 32.

Reaction chamber 32 is also preferably maintained at a substantial superatmospheric pressure and this zone is preferably insulated in order to prevent any excessive loss of heat therefrom by radiation, although insulation is not indicated in the drawing, so that conversion of the heated products supplied to this zone, and particularly their vaporous components, may continue therein. In the particular case here illustrated both vaporous andliquid conversion products are withdrawn in commingled state from the lower portion of chamber 32 through line 33 and valve 34 and are introduced into coking chamber 35. It is, however, within the scope of the present invention, although not illustrated, to separately withdraw all or any desired portion of the Vaporous conversion products from chamber 32 at any desired point in this zone, in which case they may be supplied, all or in part, by well known means not illustrated, direct to fractionator 52 or to separating chamber 40 or to coking chamber 35 at any desired point in this zone.

Coking chamber 35 is also preferably operated at a substantial superatmospheric pressure, which may be substantially the same or lower than that maintained in reaction chamber 32, but which is preferably somewhat higher than the pressure maintained in heating coil I3, in order to permit the passage of vaporous products from the coking chamber through heating coil [3 without the aid of a pump or compressor. The liquid conversion products supplied to chamber 35 are subjected to further distillation in this zone and the residual liquids are reduced therein to substantially dry coke. Preferably coking of the residual liquids is assisted by introducing a heat-carrying medium into the coking chamber, as will be later more fully described. The coke may be allowed to accumulate within the coking chamber until it is substantialy filled or until the operation of the chamber is completed for any other reason, following which the chamber is cooled, the coke removed in any suitable 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 coking chambers, although only one such zone is illustrated in the drawing, and when a plurality is employed the chambers preferably are alternately operated, cleaned and prepared for further operation so that the coking stage of the process, in common with the rest of the system, may be operated continuously. Chamber 35 is provided with a suitable drain-line 35 controlled by valve 31 which may also serve as a means of introducing water, steam or any 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 cleaning of the chamber.

The vapors evolved in coking chamber 35 will ordinarily contain some entrained -or dissolved high-boiling liquids unsuitable for conversion with the lower boiling vaporous products and, in the case here illustrated, the vapors from chamber 35 pass through line 38 and valve 39 to a suitable separating chamber 40, wherein undesirable high-boiling components and entrained or dissolved heavy liquid particles are removed from the vapors. When desired, a regulated portion of the hydrocarbon oil charging stock for the process may be directed from line 4 through line 4| and valve 42 into separating chamber 40 for the purpose of partially cooling the vaporous products from the coking chamber to assist removal of the high-boiling liquids therein. The condensate formed in chamber 40, which, when charging stock is supplied to this zone, may include some high-boiling components of the charging stock as well as high-boiling components of the vaporous products from the coking zone, may be directed from the lower portion of this chamber 40 through line 43 and valve 44 to pump 45, by means of which it is fed through line 46 and valve 41, either alone or together with high-boiling oils from column In supplied to line 46 as previouslydescribed, into reaction chamber 32 wherein these relatively heavy oils are subjected to further conversion.

Preferably the relatively heavy liquids directed to chamber 32, in the manner just described, are

directed against the walls of the chamber by means of a suitable spray or spreader device, for example, such as indicated at 49, whereby they serve as a washing liquid for the walls of the chamber to prevent the formation and deposition of coke thereon.

The vapors remaining uncondensed in separating chamber 40 are directed from the upper portion of this zone through line 50 and'valve 5! into line I l and thence to further conversion in heating coil l3, together with the low-boiling fractions of the charging stock from distilling and fractionating column 10.

The functions of heating coil 13 and heat exchanger have already been described and the vaporous conversion products from heating coil l3, having been cooled sufliciently to prevent any appreciable further conversion thereof in heat exchanger 1 and directed, as previously described, to fractionation in fractionator 52, are subjected to fractionation in any well known manner in this zone whereby their insufliciently converted components are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling point are withdrawn from the upper portion of fractionator 52, together with uncondensable gas produced in the system, and pass through line 53 and valve 54 to condensation and cooling in condenser 55. The resulting distillate and gas passes through line 56 and valve 5'! to collection and sep-' aration in receiver 58. Uncondensable gas may be released from the receiver through line 59 and valve 60. Distillate may be withdrawn from receiver 58 through line 6! and valve 62 to storage or elsewhere, as desired. When desired, a regulated portion of the distillate collected in receiver 58 may be recirculated, by well known means not shown in the drawing, to the upper portion of fractionator 52 to serve as a refluxing and cooling medium to assist fractionation of the vapors and to maintain the desired vapor outlet temperature from the fractionator.

In the case here illustrated the reflux condensate formed in fractionator 52 is separated in this zone into selected relatively low-boiling and highboiling fractions. The high-boiling fractions are withdrawn from the lower portion of the fractionator through line 53 and valve 54 to pump 65 by means of which they are fed through line 66 and may be directed through valve 61 in this line to heating coil 28 for further conversion, or, when desired, a regulated portion or all of this material may be diverted from line 66 through line 68 and valve 69 into line 46 and thence into reaction chamber 32 for further conversion in this zone.

It will be evident from the foregoing that heating coil 28 may be eliminated, when desired, in case all of the relatively high-boiling oils, comprising high-boiling fractions of the charging stock from column I0, condensate from separating chamber 40 and high-boiling fractions of the reflux condensate from fractionator 52 are supplied direct to reaction chamber 32, in the manner previously described. Heating coil 28 may be isolated from the rest of the system by closing valve 70 in line 66 and valve 3| in line 30.

Selected low-boiling fractions of the reflux condensate formed in fractionator 52 may be withdrawn from any suitable intermediate point or plurality of points in the fractionator. In the case here illustrated low-boiling reflux condensate is directed from fractionator 52 through line H and valve 12 to pump 13 by means of which it is fed through line 14 and valve 15 to conversion in heating coil 16.

Heating coil 16 is located in a furnace T! of any suitable form and the relatively low-boiling oil passing through the heating coil is heated to the desired conversion temperature, preferably at a substantial superatmospheric pressure. The stream of heated products is discharged from heating coil 16 through line 78 and may be directed, all or in part, through line 19, valve 80 and line 38 into reaction chamber 32 either alone or together with the stream of heated products from heating coil 28, in case the latter zone is employed. Preferably, however, a regulated portion at least of the hot conversion products from heating coil 16 are directed through valve 8| in this line into coking chamber 35 to commingle therein with the materials undergoing coking in this zone and supply additional heat thereto for assisting the coking operation. The highly heated materials from heating coil 76 may be introduced into chamber 35 at any desired point or plurality of points in this zone although only one point of introduction is shown in the drawing.

The fractional distilling stage of the system, as previously mentioned, is preferably operated at a superatmospheric pressure sufficient to permit the passage of the overhead vaporous stream from this zone through the succeeding heating coil without the aid of a pump or compressor. This pressure may range, for example, from approximately to 500 pounds, or more, per square inch, although, when desired, lower pressures down to substantially atmospheric may be employed in the distilling and fractionating column. The heating coil to which the low-boiling fractions of the charging stock and the vaporous products from the coking zone are supplied may utilize an outlet conversion temperature ranging, for example, from 950 to 1100 F. with any desired pressure ranging from substantially atmospheric to 500 pounds, or more, per square inch at the outlet from this zone. The products from this heating coil are preferably cooled by indirect heat exchange with the charging stock and by pressure reduction to a temperature of from 650 to 800 F.; a reduced pressure ranging from 100 pounds, or thereabouts, per square inch, down to substantially atmospheric pressure being preferred in the succeeding fractionating, condensing and collecting portions of the system. The heating coil to which the low-boiling fractions of the reflux condensate are supplied may employ an outlet conversion temperature ranging from 900 to 1000 F., for example, preferably with a superatmospheric pressure at this point in the system of from 200 to 800 pounds, or more, per square inch. When a heating coil is employed for conversion of the high-boiling fractions of the charging stock and/or the high-boiling fractions of the reflux condensate a conversion temperature ranging, for example, from 800 to 950 F. may be employed at the outlet from this zone, preferably with a superatmospheric pressure at this point in the system of from 100 to 500 pounds, or thereabouts, per square inch. The reaction chamber may employ a superatmospheric pressure ranging from 100 to 500 pounds, or thereabouts, per square inch and this pressure may be either substantially equalized or reduced in the succeeding coking chamber.

As a specific example of one of the many possible operations of the process of the present invention as it may be accomplished in an apparatus of the character illustrated and above described, a California crude of about 33 A. P. I. gravity, containing approximately 30 per cent of material boiling up to 400 F., is separated by fractional distillation into components boiling above and below approximately 600 F.; the low-boiling fractions comprising about 55 per cent of the charging stock. The high-boiling fractions are subjected in a heating coil, together with the high-boiling fractions of the reflux condensate produced within the system, to an outlet conversion temperature of approximately 920 F. at a superatmospheric pressure of approximately 300 pounds per square inch and the heated products are introduced into a reaction chamber operated at substantially the same pressure. The vaporous and liquid conversion products from the reaction chamber are introduced into a coking chamber operated at a superatmospheric pressure of about 150 pounds per square inch. High-boiling components removed from the vaporous products of the coking chamber are returned to the reaction chamber for further conversion. The remaining vaporous products from the coking chamber are subjected, together with the low-boiling fractions of the charging stock, to conversion in a separate heating coil at a temperature of approximately 1000 F. and a superatmospheric pressure of approximately pounds per square inch. The resulting productsare cooled sufficiently to prevent their further conversion, the high-boiling components removed therefrom being supplied to the fractional distilling stage of the system while the partially cooled vaporous products are subjected to fractionation for the formation of said re- 'fiux condensate. The low-boiling fractions of the reflux condensate having a boiling range of approximately 350 to 600 F. are subjected in another separate heating coil to an outlet conversion temperature of approximately 975 F. at a superatmospheric pressure of about 500 pounds per square inch. A portion of the heated products from the last mentioned heating coil are introduced directly into the coking chamber to assist the coking operation and the remainder are supplied to the reaction chamber. This op eration will produce, per barrel of charging stock, approximately 63 per cent of 400 F. endpoint motor fuel having an octane number of approximately '72 by the motor method, about 65 pounds of good quality coke, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

1. A process for the pyrolytic conversion of hydrocarbon oils which comprises subjecting charging stock for the process, comprising a hydrocarbon oil of relatively wide boiling range, to fractional distillation and separating same into selected relatively low-boiling and high-boiling fractions, subjecting the high-boiling fractions of the charging stock to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, introducing the resulting conversion products into an enlarged coking chamber and reducing their high-boiling components to coke therein, subjecting said relatively lowboiling fractions of the charging stock to pyrolytic conversion in a separate heating coil, cooling the resulting products sufficiently to prevent their excessive further conversion and to separate therefrom undesirable high-boiling materials and subjecting the remaining products to fractionation, whereby their components boiling above the range of the desired final light distillate product of the process are condensed as reflux condensateand 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, subjecting selected low-boiling fractions of said reflux condensate to independently controlled conversion conditions of higher cracking temperature and superatmospheric pressure in another separate heating coil, commingling the resulting highly heated products with the products resulting from said conversion of the high-boiling fractions of the charging stock, withdrawing vaporous products from the coking chamber, separating therefrom undesirable high boiling materials and subjecting the remaining vaporous products to further conversion in the same heating coil to which the low-boiling fractions of the charging stock are sup-plied.

2. A process as claimed in claim 1 wherein the high-boiling fractions of the reflux condensate are returned for conversion to the same heating coil to which the high-boiling fractions of the charging stock' are supplied.

3. A process as claimed in claim 1 wherein the high-boiling fractions of the reflux condensate are returned for further conversion to the reaction chamber.

4. A process for the pyrolytic conversion of hydrocarbon oils which comprises subjecting charging stock for the process, comprising a hydrocarbon oil of relatively wide boiling range, to fractional distillation and separating same into selected relatively low-boiling and high-boiling fractions, subjecting said selected low-boiling fractions of the charging stock to pyrolytic conversion in a heating coil, cooling the resulting heated products sufficiently to prevent their excessive further conversion and to remove therefrom undesirable high-boiling components, subjecting the remaining partially cooled vaporous products to fractionation, whereby their components boiling above the range of the desired final light distillate product of the process 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, subjecting the high-boiling factions of said reflux condensate to conversion conditions of cracking temperature and superatmospheric pressure in a separate heating coil and communicating reaction chamber, supplying said high-boiling fractions of the charging stock direct to the reaction chamber, introducing the resulting products into an enlarged coking chamber, reducing their high-boiling components to coke therein, subjecting lowboiling fractions of said reflux condensate to independently controlled conversion conditions of cracking temperature and superatmospheric pressure in another separate heating coil, commingling the highly heated products from the last mentioned heating coil with the products resultdrocarbon oil of relatively Wide boiling range, to 75 fractional distillation to separate it into selected relatively low-boiling and high-boiling fractions, subjecting said selected low-boiling fractions of the charging stock to pyrolytic conversion in a heating coil, cooling the resulting heated products sufiiciently to prevent their excessive further conversion and to remove therefrom undesirable high-boiling components, subjecting the remaining partially cooled vaporous products to fractionation, whereby their components boiling above the range of the desired final light distillate product of the process 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, subjecting the low-boiling fractions of said reflux condensate to conversion conditions of cracking temperature and superatmospheric pressure in a separate heating coil and communicating reaction chamber, introducing the high-boiling fractions of the charging stock and the high-boiling fractions of said reflux condensate into said reaction chamber, Withdrawing the resulting products from the reaction chamber and introducing the same into enlarged coking chamber, reducing their high-boiling components to coke therein, withdrawing vaporous products from the coking chamber, separating therefrom undesirable high-boiling materials and subjecting the remaining vaporous products to further conversion in the first mentioned heating coil together with said low-boiling fractions of the charging stock.

6. A process for the pyrolytic conversion of hydrocarbon oils which comprises subjecting charging stock for the process, comprising a hydrocarbon oil of relatively wide boiling range, to fractional distillation to separate it into selected relatively low-boiling and high-boiling fractions, subjecting said selected low-boiling fractions of the charging stock to pyrolytic conversion in a heating coil, cooling the resulting heated products sufficiently to prevent their excessive further conversion and to remove therefrom undesirable high-boiling components, subjecting the remaining partially cooled vaporous products to fractionation, whereby their components boiling above the range of the desired final light distillate product of the process 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, subjecting the low-boiling fractions of said reflux condensate to conversion conditions of cracking temperature and superatmospheric pressure in a separate cracking zone, introducing the high-boiling fractions of the charging stock and the high-boiling fractions of said reflux condensate into said separate cracking zone, withdrawing the resulting products from the separate cracking zone and introducing the same into enlarged coking chamber, reducing their high-boiling components to coke therein, withdrawing vaporous products from the coking chamber, separating therefrom undesirable highboiling materials and subjecting the remaining vaporous products to further conversion in the first mentioned heating coil together with said low boiling fractions of the charging stock.

JACQUE C. MORRELL.

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