US2166820A - Conversion of hydrocarbon oils - Google Patents

Description

July 18, 1939.

J. c. MORREL L CONVERSION OF HYDROCARBON. OILS Original Filed Dec. 30, 1935 INVENTOR Patented July 18, 1939 UNITED STATES PATENT ()FFIQE CONVERSION OF HYDROCARBON OILS .iacque C. Morrell, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware 3 Claims.

This is a continuation of my co-pcnding application Serial Number 56,690 filed December 30, 1935.

This invention refers to an improved process for the seiective pyrolytic conversion of relatively low-boiling and liiglnboiling hydrocarbon oils wherein charging stock for the process, comprising an oil of relatively wide boiling range, is subjected to substantial vaporization under noncracking conditions, its high-boiling non-vaporous components subjected to conversion together with high-boiling intermediate liquid conversion products of the process while relatively low-boiling intermediate liquid conversion products of the process are subjected to conversion under independently controlled conditions of cracking temperature and superatmospheric pressure, the resulting products commingled with the vaporized relatively low-boiling fractions of the charging stock, and the commingled materials subjected to continued conversion in a high pressure reaction chamber.

In one embodiment, the invention comprises heating charging stock for the process, comprising a hydrocarbon oil of relatively wide boiling range, to a temperature sufficient to effect its substantial vaporization, introducing the heated oil into a topping still wherein its vaporous and nonvaporous components are separated, withdrawing the non-vaporous high-boiling components of the charging stock from the topping still, subjecting the same to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil, introducing the heated products into an enlarged reaction chamber, also maintained at substantial superatmospheric pressure, wherein vaporous and residual liquid conversion products are separated and the latter are subjected to appreciable further conversion, separately withdrawing vaporous and residual liquid conversion products from the reaction chamber, subjecting the vapors 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, returning said highboiling fractions of the reflux condensate to the 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, introducing the heated products from said separate heating coil into the reaction chamber and supplying said vaporous, low-boiling components of the charging stock from the topping chamber to the reaction chamber, wherein they commingle with the vaporous components of the hot conversion products from said heating coils and are subjected therewith to conversion.

The features of the invention and their advantages will be apparent to those familiar with the cracking art, particularly with reference to the accompanying diagrammatic drawing and the following description of the drawing. The drawing illustrates one specific form of apparatus in which the process of the invention may be accomplished.

Referring to the drawing, charging stock for the process, preferably comprising a hydrocarbon oil of relatively wide boiling range, such as crude petroleum, topped crude or the like, is supplied through line I and valve 2 to pump 3 by means of which it may be fed through line 4, line 5 and valve 6 into heating coil l. The heating coil is located within a furnace 8 of suitable form whereby sufiicient heat is imparted to the charging stock to effect its substantial subsequent vaporization in topping chamber iii, to which the heated charging stock is supplied from heating coil 1 through line 9, valve It and line 4.

The charging stock may, of course, be supplied with all or a portion of the heat required for its vaporization in chamber i2 by any other well known method of heating, not illustrated in the drawing, which may comprise, for example, indi rect heat exchange with one or more of the vari- 2.

one relatively hot intermediate or final products of the process or, when desired, a suitable heating coil for the charging stock may be positioned in a relatively low temperature zone if either or both of the cracking furnaces of the system or fiue pressure than that employed in the reaction chamber of the system in order to permit introduction of the vaporous products from the topping chamber into the reaction chamber without the aid of a pump or compressor. It is, however, entirely within the scope of the invention to utilize a suitable pump or compressor for the purpose, particularly since the temperature of the vaporous products is relatively low and they are not of a coke-forming nature. In the case here illustrated, provision is made for supplying the vaporous products from chamber 52 to reaction chamber through line l3 and valve M. The high-boiling components of the charging stock which remain unvaporized in chamber 2 are withdrawn from the lower portion of this zone through line l5 and valve IE to pump H by means of which they are supplied through line l8, valve l9 and line 20 to conversion in heating coil 2|.

A furnace 22 of suitable form supplies the required heat to the relatively high-boiling oil passing through heating coil 2| to subject the same to the desired cracking temperature, preferably at a substantial superatmospheric pressure and the hot conversion products are discharged from the heating coil through line 23 and valve 24 into reaction chamber 25.

Chamber 25, as previously indicated, is preferably operated at a substantial superatmospheric pressure and, although not indicated in the drawing, 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 appreciable continued conversion therein. The relatively low-boiling vaporous components of the charging stock commingle in the reaction chamber with the hot conversion products, supplied to this zone from heating coil 2|, as previously described, and from heating coil 5|, as will be later described. The low-boiling components of the charging stock are thereby heated to a conversion temperature and are subjected, together with the vaporous conversion products with which they are cornmingled, to conversion during their passage through the reaction chamber. Preferably, as in the case here illustrated, the vaporous products from chamber I2 and the hot conversion products from the heating coils are introduced into the lower portion of the reaction chamber wherein residual liquid conversion products are quickly separated from the vapors and withdrawn from the lower portion of the chamber through line 26 and valve 2'! to cooling and storage or elsewhere, as desired, while the commingled vapors pass upwardly through the chamber wherefrom they are directed through line 23 and valve 29 to fractionation in fractionator 30.

The components of the vaporous products supplied to fractionator 30 boiling above the range of the desired final light distillate product of the process are condensed in this zone as reflux condensate which is separated by fractional condensation into selected relatively low-boiling and high-boiling fractions which are subjected to selective further conversion within the system, as will be later described.

Fractionated vapors of the desired endboiling point are withdrawn from the upper portion of fractionator 30 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. Uncondensed gases may be released from the receiver through line 31 and valve 38. Distillate may be withdrawn from receiver 36 through line 33 and valve 40 to storage or to any desired further treatment. When desired, regulated quantities of the distillate collected in receiver 36 may be recirculated by well known means (not shown) to 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 30 are withdrawn from the lower portion of this zone through line 4| and valve 42 to pump 43 by means of which they are returned through line 44, valve 45 and line 20 to conversion in heating coil 2|, together with the high-boiling components of the charging stock supplied to this zone from chamber I2, as previously described.

The selected relatively low-boiling fractions of the reflux condensate are withdrawn from one or a plurality of suitable intermediate points in the fractionator and, in the case here illustrated, they are directed by means of line 46 and valve 41 to pump 48 by means of which they are supplied through line 49 and valve 50 to conversion in heating coil 5|.

Heating coil 5| is located within a suitable furnace 52 by means of which the required heat is supplied to the relatively low-boiling oil passing through the heating coil to subject the same to the desired relatively high conversion temperature preferably at a substantial superatmospheric pressure. The highly heated products are discharged from heating coil 52 through line 53 and valve 54 into reaction chamber 25 wherein they commingle with the other oils supplied to this zone, as previously described, increasing their temperature and assisting their continued conversion in the reaction chamber.

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: The cracking coil to which the relatively high-boiling oils are supplied preferably employs an outlet conversion temperature of the order of 800 to 950 F., preferably with a superatmospheric pressure, measured at this point in the system, of from 100 to 500 pounds, or thereabouts, per square inch. The cracking coil to Which the relatively low-boiling oils are supplied preferably employs a conversion temperature, measured at the outlet therefrom, of the order of 900 to 1050 F., and preferably a superatmospheric pressure is employed at the outlet from this heating coil ranging, for example, from 200 to. 1000 pounds, or thereabouts, per square inch. The reaction chamber may be operated at any desired superatmospheric pressure ranging from 100 to. 500 pounds, or more, per square inch which, however, is no greater than the pressure employed in the communicating heating coil utilizing the lowest pressure. The fractionating, condensing and collecting portions of the system may employ pressure substantially the same or lower than that employed in the reaction chamber, the preferred range in this portion of the system being from 150v pounds, or thereabouts, per square inch to substantially atmospheric pressure. The topping chamber, as previously mentioned, is preferably operated at a slightly higher superatmospheric pressure than that employed in the reaction chamber although lower pressures down to substantially atmospheric may be employed in this zone, when desired. The temperature to which the charging stock is. heated, prior to its introduction into the topping column, will depend, primarily, upon the nature of the charging stock and the pressure employed 7:;

in this zone and may vary over a relatively wide range, for example, from 450 to 775 F.

As a specific example of one of the many possible operations of the process as it may be accomplished in an apparatus such as illustrated and above described, the charging stock is a California crude of about 302 A. P. I. gravity containing approximately 25% of material boiling up to 400 F. The charging stock is heated to a temperature of approximately 750 F. and introduced into a topping chamber operated at a superatmospheric pressure of approximately 210 pounds per square inch, from which its vaporous components are supplied to the reaction chamber of the system. Non-vaporous components of the charging stock are withdrawn from the topping chamber and subjected, together with highboiling components of the reflux condensate from the fractionator of the system, in the heavy oil cracking coil, to an outlet temperature of approximately 920 F. at a superatmospheric pressure of about 200 pounds per square inch. Substantially the same pressure is employed in the reaction chamber. The low-boiling fractions of the reflux condensate from the fractionator of the system, having a boiling range of approximately 385 to 570 F., are subjected in the light oil heating coil of the system to an outlet conversion temperature of approximately 950 F. at a superatmospheric pressure of about 400 pounds per square inch and the heated products from this zone are also introduced into the reaction chamber. Non-vaporous liquid residue is withdrawn from the reaction chamber and the vaporous products of this zone, after being subjected to continued conversion therein, are supplied to the fractionator of the system. In this operation the hot vaporous conversion products from the reaction chamber are passed in indirect heat exchange with the charging stock, prior to their fractionation, whereby a substantial portion of the heat required for distillation of the charging stock is imparted thereto. This operation will produce, per barrel of charging stock, approximately 67% of motor fuel of good anti-knock value and about 16% of good quality liquid residue suitable as fuel, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

1. A process for converting hydrocarbon oils into high yields of gasoline, which comprises simultaneously and separately cracking light and heavy reflux condensates, formed as later described, each under independently controlled cracking conditions in a separate heating coil, introducing the resulting heated products into the lower portion of an enlarged vertically disposed reaction chamber, simultaneously and separately heating hydrocarbon oil charging stock for the process to a temperature below that at which any substantial cracking thereof will oc-' cur but sufiicient to effect vaporization of its lowboiling components, separating the resulting vaporous and liquid components of the charging stock out of contact with cracked products formed in the process, supplying said liquid components for cracking to the same heating coil to which said heavy reflux condensate is supplied, supplying said vaporous components of the charging stock, without prior heating of the same to cracking temperature and without previously comrningling the same with cracked products, to the lower portion of said reaction chamber, therein commingling said vaporous components of the charging stock with the relatively hot vaporous components of the cracked products supplied to this zone, quickly removing liquid conversion products from the lower portion of the reaction chamber, passing the commingled vapors, at an active cracking temperature resulting from the heat contained in said vaporous cracked products, upwardly through the reaction chamber, thereby cracking said vaporous components of the charging stock in this zone, separately removing the resulting vaporous products from the upper portion of the reaction chamber, fractionating the same independently of said charging stock to form said light and heavy reflux condensates, condensing resulting fractionated vapors of the desired end-boiling point without further heating thereof and recovering the resulting distillate as said gasoline product.

2. A process for the conversion of hydrocarbon oils into high yields of gasoline, which comprises heating a hydrocarbon oil charging stock of relatively wide boiling range to a temperature below that at which any substantial cracking thereof will occur but sufliciently to effect vaporization of its low-boiling components at substantial superatmospheric pressure, supplying the heated charging stock to an enlarged chamber maintained at substantial superatmospheric pressure and therein separating its vaporous and liquid components out of contact with cracked products formed in the process, supplying said liquid components to a heating coil and therein heating the same to cracking temperature at substantial superatmospheric pressure, simultaneously heating an oil of lower boiling characteristics to an independently controlled higher cracking temperature at substantial superatmospheric pressure in a separate heating coil, supplying resultant highly heated products from both of said heating coils to an enlarged reaction chamber also maintained at substantial superatmospheric pressure, separately removing only said vaporous components of the charging stock from the first mentioned chamber and supplying the same, by means of the pressure under which the charging stock is heated as previously described, to the reaction chamber, therein heating said vaporous components of the charging stock, for the first time, to an active cracking temperature by commingling the same with the highly heated vaporous components of the cracked products supplied to this zone from said separate heating coils, maintaining the commingled vapors at an active cracking temperature for an appreciable time in said reaction chamber and thence removing the resulting vaporous products therefrom, more quickly removing liquid conversion products from the reaction chamber, fractionating the vaporous products removed from the reaction chamber independently of said charging stock to condense therefrom light and heavy reflux condensates, returning heavy reflux condensate formed by said fractionation to the first mentioned heating coil for further cracking, returning light reflux condensate formed by said fractionation to said separate heating coil for further cracking, removing fractionated vapors of the desired end-boiling point from the zone of said fractionation and condensing and recovering therefrom said gasoline product without further heating thereof.

3. A process for the conversion of hydrocarbon oils into high yields of gasoline, which comprises heating a hydrocarbon oil charging stock of relatively wide boiling range to a temperature below that at which any substantial cracking thereof will occur but sufiiciently to effect vaporization of its low-boiling components at substantial superatmospheric pressure, supplying the heated charging stock to an enlarged chamber maintained at substantial superatmospheric pressure and therein separating its vaporous and liquid components out of contact with cracked products formed in the process, supplying said liquid components to a heating coil and therein heating the same to cracking temperature at substantial superatmospheric pressure, simultaneously heating an oil of lower boiling characteristics to an independently controlled higher cracking temperature at substantial superatmospheric pressure in a separate heating coil, supplying resultant highly heated products from both of said heating coils to an enlarged reaction chamber also maintained at substantial superatmospheric pressure, separately removing only said vaporous components of the charging stock from the first mentioned chamber and supplying the same, by means of the pressure under which the charging stock is heated as previously described, to the reaction chamber, therein heating said vaporous components of the charging stock, for the first time, to an active cracking temperature by commingling the same with the highly heated vaporous components of the cracked products supplied to this zone from said separate heating coils, maintaining the commingled vapors at an active cracking temperature for an appreciable time in said reaction chamber and thence removing the resulting vaporous products therefrom, more quickly removing liquid conversion products from the reaction chamber, fractionating said vaporous products removed from the reaction chamber without commingling the same in the fractionating zone with the uncracked charging stock, condensing from the vaporous products undergoing said fractionation a reflux condensate of lower boiling characteristics than said liquid components of the charging stock, supplying said reflux condensate, as said oil of lower boiling characteristics, to the second mentioned heating coil, removing fractionated vapors of the desired end-boiling point from the fractionating zone and condensing and recovering therefrom the desired gasoline product without further heating thereof.

JACQUE C. MORRELL.

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