US2254551A - Conversion of hydrocarbon oils - Google Patents

Description

Patented Sept. 2, 1941 2,254,551 CONVEBSION F EYDBOCAEBON OILS Kenneth 8 Chi go. 111., amino! to wartwood, Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application May 9, 1938, Serial No. 206,767

6 Claims. (Cl. 196-49) This is a continuation-in-part of my co-pending application Serial Number 87,944, filed June 29, 1936, now abandoned.

The invention relates to an improved process and apparatus for the selective py lytic conversion of relatively low-boiling and relatively highboiling hydrocarbon oils, accompanied by coking of the residual liquid conversion products and fractional distillation of the hydrocarbon oil charging stock for the process in commingled state with vaporous products of the coking operation to form a relatively clean condensate comprising the heavy cracking stock, heated products of the heavy oil cracking operation being utilized to supply heat to and assist coking of the residual liquid products of the light oil cracking operation.

One specific embodiment of the process of the invention comprises subjecting reflux condensate, formed as subsequently described, to conversion conditions of cracking temperature and superstmospheric pressure in a heating coil and communicating enlarged reaction chamber, supplying resultant vaporous and liquid conversion products to a reduced pressure chamber, wherein vapors and non-vaporous residual liquid are separated, fractionating the vapors to form said reflux condensate which is supplied to the heating coil, removing non-vaporous liquid residue from said reduced pressure chamber, introducing the same into a coking chamber wherein it is reduced to coke, removing from the vaporous products of the coking operation entrained high cokeforming liquid particles by passing said vapors in indirect heat exchange with hydrocarbon oil charging stock for the process, fractionating the resulting relatively clean vapors, in commingled state with said charging stock and in a fractionating zone separate from that wherein the first mentioned vapors are fractionated, to form a relatively clean heavy condensate comprising highboiling components of the charging stock and high-boiling components of said relatively clean vapors, heating said relatively clean heavy condensate to cracking temperature at superatmospheric pressure in a separate heating coil, introducing resulting heated products into the coking chamber to supply additional heat thereto and assist the coking operation, introducing relatively low-boiling components of the charging stock and of said relatively clean vaporous products of the coking operation, resulting from. the last described fractionating step, to the first mentioned fractionating step and therein further fractionating the same in commingled state with the first mentioned vapors, condensing vaporous products of the desired end-boiling point from the first mentioned fractionating step and recovering the resulting distillate.

As an additional feature of the invention, when desired, residual liquid removed from said reduced pressure chamber may be quickly heated in another separate heating coil of the system to a high cracking temperature under non-coking conditions and thence introduced into the coking chamber.

It is also within the scope of the invention to condense and recover selected low-boiling components of the charging stock and of the relatively clean vaporous products of the coking operation separate from the distillate product recovered from the first described fractionating step or, when desired, all or regulated quantities of the distillate resulting from said separate condensation may be supplied as a cooling and refluxing medium to the first mentioned fractionating step and therein at least partially vaporized and subjected to further fractionation with the vaporous products of the first mentioned cracking operation.

The features and advantages of the invention will be readily understood. by referring to the accompanying diagrammatic drawing and the following description thereof. The drawing illus- Referring to the drawing, heating coil 1, to I which intermediate liquid products of the process are supplied, as will be later described, is located in a suitable furnace 2. This furnace supplies the required heat to the 011 assing through the heating coil to subject it to the desired conversion temperature, preferably at a substantial superatmospheric pressure, and the resulting heated products are discharged through line 3 and valve 4 into reaction chamber 5.

Chamber 5 is also preferablymaintained at a substantial superatmospheric pressure and, although not indicated in the drawing, is preferably insulated to conserve heat so that the heated products supplied to this zone, and more particularly their vaporous components, are subjected to appreciable continued conversion therein. In the particular case here illustrated both vaporous and liquid conversion products are withdrawn in commingled state from the lower portion'of chamber 5 and are directed through line I and valve 1 intovaporizing chamber 8.

It is also within the scope of the invention, when desired, to separate vaporous and liquid conversion products in chamber 5, supplying the latter, eitheralone or together with a regulated portion of the vapors, to chamber 8, in the manner illustrated and described, and supplying the vaporous products, separately withdrawn from any desired point or plurality of points in chamber 5 to chamber I or to iractionator II, or in trated.

Chamber 8 is preferably maintained at a substantially reduced pressure relative to that employed in the reaction chamber,- by meansof which appreciable further vaporization of the liquid products supplied to thiszone is accomplished. Separation of vapors and non-vaporous residual liquid is accomplished in chamber 8, the

latter being withdrawn therefrom to subsequent treatment, as will be later described, while the vaporous products pass from the upper portion of the chamber through line I and valve I! to fractionation in fractionator ll.

Components of the vaporous products supplied to fractionator II which boil above the ran e of the desired final light distillate product of this stage of the process are condensed in this zone as reflux condensate. Reflux condensate is withdrawn from the lower portion of the fractionator through line l2 and valve II to pump l4 by means of which it is supplied through line II and valve II. to said conversion in heating coil I.

Fractionated vapors of the desired end-boiling point are withdrawn from the upper portion of fractionator Ii, together with uncondensable gas produced by the cracking operation, and this material is directed through line l1 and valve II to condensation and cooling in condenser II. The

resulting distillate and gas passes through line 2| and valve 2| to collection and separation in receiver 22. Uncondensable gas'may be released from the receiver through line 23 and valve 24. Distillate may be withdrawn from receiver 22 through line 25 and valve 2! to storage or to any desired further treatment. When desired, regulated quantities of the distillate collected in receiver 22 may be recirculated by well known means, not illustrated in the drawing, to the upper portion of fractionator II to serve as arefluxing and cooling medium in this zone for assisting fractionation of the vapors and to maintain the desired vapor outlet temperature therefrom.

Residual liquid remaining unvaporized in chamber 8 is directed from the lower portion of this zone through line 21 and valve 28 to pump 2| by means of which it is fed through line II and may be introduced directly through valvell, in this line, into coking chamber 32 wherein it is reduced to coke. When desired, the residual liquid from chambar 8 may be passed through heating coil 02,

prior to its introduction into chamber 32, by means of lines ll and 84 having the respective valves 8i and ll.

Heating coil 3! is located within furnace II and, preferably, this heater is one of the well known forms in which the residual liquid may bequickly heated to coking temperature without allowing it to remain in the heating coil and communicating lines for sufficient time to permit the formation and deposition of coke therein, the actual coke deposition taking place in ther operation. A plurality of coking chambers may, of course. be employed, when desired, althoughonlyasinglechamberisshowninthe rest of the system, in order to hasten cooling, and

facilitate removal of the coke.

.Vaporous products of the coking operation are removed from the upper portion of chamber 22 and directed through line It and valve 36 to a zone wherein high coke-forming components of the vapors, such as entrained heavy liquid particles, are removed therefrom, prior to their fractionation for the formation of relatively clean condensate. This is accomplished, in .the case here illustrated, by passing the vapors through heat exchanger 21 in indirect heat exchange with a suitable cooling medium such as, for example, hydrocarbon oil charging stock for the process. The heavy liquids removed from the vapors in heat exchanger 21 may be directed from the lower portion of this zone through line 38 and valve a back into coking chamber 32 for further treatment and reduction to coke in this zone or they may, when desired, be supplied by well known means, not illustrated, to heating coil 82 or to vaporizing and separating chamber 8. The relatively clean vapors, from which substantially all entrained heavy liquid particles and similar high coke-forming materials have been removed in heat exchanger 31, are directed therefrom through line 40 and valve 4| to fractionation in fractionator 42.

Charging stock for the process, which preferably comprises hydrocarbon oil of relatively wide boiling range such as, for example, crude petroleum or topped crude, is supplied through line 43 and valve 44 to pump 4' wherefrom it is fed through line 4t and may be introduced, all orin part, through line 41 and valve 44 into fractionator 42. When utilized as a cooling medium in heat exchanger 31, all or a regulated portion of the charging stock is supplied thereto through line and valve ill and, after being preheated by indirect heat exchange with the vapors from the coking chamber in heat exchanger 31, it is directed through line Ii, valve I2 and line 41 into fractionator 42. It is entirely within the scope .of the invention, when desired, to preheat the charging stock in any well known manner prior of or in conjunction with the method of preheating above described or preheating of the charging stock may be omitted, when desired. In any case at least a substantial portion of the heat required for fractional distillation of the charging stock is supplied thereto by directly commingling the same with the relatively hot vaporous products of the coking operation.

The charging stock is directly commingled in fractionator 42 with the relatively clean vaporous products of the coking operation and subjected to fractionation therewith. This fractionation results in the formation of a relatively clean heavy condensate comprising high-boiling components of the charging stock and highboiling components of the relatively clean vaporous products of the coking operation. This relatively clean heavy condensate is directed from the lower portion of fractionator 42 through drawing. Preferably. two or more such chain line it an valve 54 to pump it by means of which it is supplied through line 56 and valve 57 to heating coil 58. w

Furnace 59 supplies required heat to the relatively heavy oil passing through coil 58 to efl'ect substantial cracking thereof in this zone, preferably at a substantial superatmospheric pressure. Resulting heated products are discharged from coil 58 through line 60 and valve 6| into coking chamber 32 wherein they serve as a heat carrying medium for supplying additional heat to and assisting the coking operation.

The relatively clean vapors supplied to fractionator 42, as above described, and the vapors evolved from the charging stock in this zone will contain an appreciable quantity of lowboiling fractions which may be more advantageously cracked in light oil heating coil I than in heavy oil heating coil 58. They will also normally contain fractions boiling within the range of the desired final light distillate product of the process. These latter fractions comprise gasoline components of the charging stock (when the charge is a gasoline-containing crude oil) and gasoline formed by the cracking operation in coil 58. Therefore, fractionation is preferably so controlled in fractionator 42 that at least a major portion of the components of the materials supplied thereto which may be advantageously cracked in coil I and substantially all of the gasoline boiling range fractions .of these materials, are removed as overhead vapors from fractionator 42 through line 62. This vaporous stream may be directed from line 62 through line 63' and valve 64 into fractionator II, to commingle therein and undergo further fractionation with the vaporous products from chamber 8, whereby the low-boiling fractions of this vaporous stream, desirable as components of the final light distillate product of the process, are recovered in receiver 22, while its higher boiling fractions are condensed as a component of the reflux condensate supplied from fractionator II to heating coil I:

Instead of or in conjunction with supplying vapors from fractionator 42 to fractionator II, it is alsowithin the scope of the invention to direct all or a portion of these vapors through valve 65 in line 62 to condenser 66 wherein their normally liquid components are condensed and wherefrom the condensate is supplied, together with uncondensed gases, through line 61 and valve 68 to collection and separation in receiver 69. All or a regulated portion of this relatively light condensate may be directed from receiver 69 through line I and valve 'H to storage or elsewhere as desired, while uncondensed gases are released from receiver 69 through line I2 and valve 13. Preferably, however, all or at least a portion of the condensate The preferred range of operating conditions which may be employed to accomplish the objects of the invention, in an apparatus such as illustrated and above described, may be approximately as follows: Heating coil I preferably employs an outlet temperature of the order of 850 to 950 F., or more, with a superatmospheric pressure. measured at the outlet from coil I, which may range, for example, from 100 to 500 pounds, or more, per square inch.

- substantially the same or somewhat lower than recovered in receiver 69 is directed therefrom through line 10' and valve 14 to pump 15 by means of which it is supplied through line 16 and valve 11 to fractionator H, wherein it commingles with the vapors supplied to this zone from chamber 8, serving to partially cool the latter and assist their condensation and being subjected to fractionation therewith in the manner previously described Provision is also made, in the case here illustrated, for returning that utilized in chamber 8.

When heating coil 82 is employed, the residual liquid passing through this zone preferably is quickly heated to a temperature of the order of 900 to 1000" F., or more, although lower temperatures may be employed, when desired. Any desired. pressure may be employed at the outlet of coil 82, the preferred range being from 20 to pounds, or thereabouts, per square inch, superatmospheric.

The coking chamber may employ any desired pressure not greater than that utilized at the outlet of the communicating heating coil employing the lowest pressure.

The pressure employed in the coking chamber may be substantially equalized or reduced in the succeeding heat exchange, fractionating, condensing and collecting equipment.

Preferably, the relatively heavy oil supplied to coil 58 is heated therein to an outlet cracking temperature of the order of 850 to 950 F., or

. more, preferably with a superatmospheric pressure at this point in the system of the order of 100 to 300 pounds, or more, per square inch. Preferably, the heavy oil passed through coil 58 is subjected to less drasticcracking conditions than the relatively light oil supplied to coil i, although the temperature or pressure, or both, employed in coil 58 may, when desired, be higher than that employed in coil I, particularly when the coking chamber is operated at a lower pressure which is not conducive to extensive further cracking in this zone of the heated products supplied thereto from coil 58.

As a specific example of an operation of the process, as it may be conducted in an apparatus such as illustrated and above described, the

charging stock is a Kansas crude of approxiis thence introduced into the fractionator of regulated quantities of the condensate collected in receiver 69 to the upper portion of fractionator 42 to serve as a cooling and refluxing medium in this zone, this being accomplished by means'of line 18 and valve 19.

the coking stage of the system. The fractionated vapors removed from the upper portion of 7 this zone have an end-boiling point of approximately 680 F., while the heavier fractions of the vapors and charging stock supplied to this fractionator are removed as heavy cracking stock from the lower portion 01 this zone and supplied to the heavy oil cracking coil. The overhead vapors iromgthis iractionator are condensed and the condensate is supplied to the other fractionator oi the system, wherefrom the final light distillate product of the process is recovered and wherefrom reflux condensate is supplied to the light oil heating coil. A cracking temperature of the order of 970 F. and a superatmospheric pressure of about 350 pounds per square inch is employed at the outlet of the light oil cracking coil and subtantially the same pressure is employed in the succeeding reaction chamber. The vaporizing and separating chamber, to which both vaporous and liquid conversion products from the reaction chamber are supplied, is operated at a superatmospheric pressure of approximately 175 pounds per square inch. Substantially the same pressure is employed in the succeeding fractionator. The residual liquid removed from the vaporizing and separating chamher is quickly heated to a temperature of approximately 930 F. and thence introduced into the coking chamber. The pressure employed at the outlet of the residuum heating coil is approximately 35 pounds per square inch and substantially the same pressure is employed in the coking chamber. The heavy oil cracking stock supplied from the first mentioned iractionator to the heavy oil heating coil is heated therein to an outlet cracking temperature of approximately 950 F. at a superatmospheric pressure of about 200 pounds per square inch and the resultin highly heated products are introduced into the coking chamber.

The above described operation will Yield, per barrel of charging stock, approximately 64% of good quality gasoline, a portion of which com prises straight run gasoline recovered from the crude, while the remainder is-gasoline produced by cracking. Approximately 85 pounds or low volatile coke is produced in the coking chamber, per barrel oi crude oil supplied to the system, and the remainder of the crude is chargeable principally to gaseous products and loss.

I claim as my invention: a

l. A hydrocarbon oil conversion process which comprises, cracking reflux condensate formed as subsequently described, separating resultant vaporous and residual liquid conversion products, fractionating the vapors to form the reflux condensate subjected to said cracking. removing residual liquid from the zone 01' said separation,

' characterized in that 'said low-boiling composup lying the same to a separate zone wherein it is reduced to coke, removing from the vaporous products 01' the coking operation entrained high coke-forming particles, fractionating the remaining relatively clean vaporous products of the coking operation separately from the vaporous products of said cracking operation and in comminagled state with hydrocarbon oil charging stock for the process to form a relatively clean heavy condensate comprising high-boiling components of said vaporous products of the coking. operation and high-boiling components of the charging stock, separately cracking the relatively clean heavy condensate, introducing heated products of the last mentioned cracking operation into the coking zone to supply additional heat thereto and assist the coking operation. condensing fraction ated vapors oi the desired end-boiling point and recovering the resulting distillate, and supplying nents are supplied as vapor from the secondi mentioned fractionating step to the first-mentioned fractionating step.

3. A process such as defined in claim 1, where- 'in residual liquid from said zone or separation is supplied to the coking zone without additional prior heating.-

4. A process such as defined in claim 1, wherein residual liquid removed from said zone of separation is heated to a high cracking temperature under non-coking conditions in a heating coil and thence introduced into the coking zone.

5. The process as defined in claim 1 further characterized in that said low-boiling components from the second-mentioned fractionating step are condensed and introduced in liquid form to the first mentioned i'raotionating step.

6. A hydrocarbon oil conversion process which comprises heating reflux condensate, formed as subsequently described, to cracking temperature at superatmospheric pressure in a-heating coil, supplying the heated products to an e larged reaction chamber also maintained at superatmospheric pressure, wherein cracking continues, supplying both vaporous and liquid products from the reaction chamber to a vaporizing and separating chamber operated at a lower superatmospheric pressure than that maintained in the reaction chamber and therein separating the vaporous and residual liquid products, supplying additional heat to the latter under non-coking conditions in a separate heating coil and thence introducing the same into a coking zone wherein they are reduced to coke, removing vaporous products from the coking zone, passing the same in indirect heat exchange with hydrocarbon oil charging stock for the process whereby to remove high coke-forming components from the vapors and preheat the charging stock, returning said removed high coke-forming components to the coking zone for further treatment, supplying the remaining relatively clean vaporous products of the coking operation to a iractionating zone, therein commingling the same. with the preheated charging stock and iractionating the mixture to form a heavy condensate substantially devoid oi the tars and similar high coke-forming materials entrained in the vapors removed from the coking zone, heating said heavy condensate, in the absence 01' said high coke-forming materials. to cracking temperature at superatmospheric pressure in another separate heating coil, introducing resultant heated products into the coking zone to supply additional heat to and assist the coking operation, removing fractionated vapors of the desired end-boiling point from the iractionating zone, subjecting the same to codensation, commingling resulting distillate in a separate fractionating zone with said vaporous products removed from the vaporizing and sepato the first-mentioned fractionating step relatively low-boiling components of the charging stock and of the vaporous products of the coking rating chamber and therein iractionating the mixture to form the reflux condensate supplied to the first mentioned heating coil, subjecting fractionated vapors oi the desired end-boiling point from the last mentioned tractionating zone to condensation and recovering the resulting distillate.

' e KENNETH SWARTWOOD.

operation,resulting from the second-mentioned

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