US2111354A - Cracking of petroleum oil - Google Patents

Description

March 15, 1938. D. G. BRANDT CRACKING 0F PETRLEUM OIL Filed July 27, 1932 DAvm G BRANDT n INVENTOR u ATTORN 7111,11! i 1 Mw.. -I

Patented Mar. 15, 1938 CRACKING OF PETROLEUM OIL David G. Brandt, Westiield, N. J., assignor to Power Patents Company, Hillside, N. J., a corporation of Maine Application July 27, 1932, Serial No. 624,979

10 Claims.

This invention relates to a process and apparatus for cracking mineral oil in a combined cracking operation.

The present application is a continuation in part of the applicants pending application Serial No. 532,953, liled January 31, 1922.

The primary object of the present invention is the provision of an elective cracking process which involves the feature of cracking certain high boiling point oil stocks by the use of heat and temperature derived from highly heated products of a high temperature cracking operation.

Petroleum oil contains several fractions such as kerosene, gas oil and fuel oil residue which may be converted into motor fuel by cracking at suitable temperatures. As a general rule the lower the boiling point of the oil fraction, the higher the temperature necessary for cracking, particularly if the fraction has not been previously subjected to cracking conditions.

In accordance with the features of this invention, it is the further object thereof to provide an oil cracking process in which an oil fraction of relatively low boiling point is cracked at high temperature, and the resulting products utilized to supply the heat and temperature necessary for cracking a higher boiling point more easily cracked stock, at a lower temperature than that used for cracking the low boiling point oil.

With these and other objects and advantages in View the invention may be described in connection with the accompanying drawing in which:

The ligure is a diagrammatic view of an apparatus particularly adapted for carrying out the process.

Referring to the drawing, the operation is preferably initiated by lling the heating coils and chambers with oil and then starting the ring of the furnace. Thereafter charging stock such as gas oil is introduced through a line 2, pump 4 and feed line 8, into the cracking apparatus. This charging stock passes through a series of p-reheating coils 8 mounted in a fracticnating tower i0, and passes through valved pipes l2, I3, and i4 into the lower portion of tower Il) which may be used as an accumulation chamber. From this point the oil is conducted through valved pipes I6 and i8 and forced by means of a pump 20 through a heating coil 22 mounted in pipe still furnace 24. The oil discharged from the coil 22 is conducted through a pipe 28 into an enlarged separating chamber 28 from which the liquid oil and any vapor formed during the starting operation are passed through a line 32 and into coil 34. The heated oil from coil 34 is discharged through a transfer line 36 into the lower portion of an enlarged cracking chamber 38. During the heating up operation oil from chamber 38 may be recirculated through the heating coils by passing it through lines 48, 39, I3, and I4 into the lower portion of tower lll. After the temperature in the coils has been brought up to the desired point the relatively cold oil in the lower part of chamber 28 is slowly withdrawn through a line lil into chamber 38. This will lower the oil level in chamber 28 so that only vapors pass to the line 32. The recirculation of oil from chamber 38 through the coil 22 is discontinued as soon as the body of oil in this chamber has been brought up to the cracking temperature.

Vapors separated in separator 28 are conducted through vapor line 32 and passed through vapor cracking tube bank 34 mounted in the upper portion of furnace 24. The vapors passing through the tube bank 34 are heated to a cracking temperature of from 950 to 1050" F. so that a very substantial conversion of the oil constituents is effected. The highly heated vapor products are conducted from tube bank 34 through vapor line 36 and introduced into the lower portion of the enlarged cracking chamber 38 in which a substantial body of high boiling 'point oil is maintained and cracked by the heat and temperature derived from the introduced vapors. The body of oil in the chamber 38 preferably comprises such high boiling point material as stripped crude or oil r-esiduurn, which will be much more easily cracked than materials such as kerosene or gas oil. After the operation has been initiated, the supply of gas oil through pipe 2 is discontinued, and the heavy stock for chamber 38 is introduced into the system through the pump 4, and conducted from the coil 8 through pipes l2, I3, 39, and 40 into the upper portion of chamber 38.

The highly heated and cracked vapors introduced through pipe 36 into the body of oil in chamber 38 cause a very substantial heating and cracking of the heavy oil in this chamber and thereby produce an additional amount of low boiling point product. The combined vapors formed in the system are conducted from the chamber 38 through a vapor line 42 into the fractionating tower I0 where the vapors pass in indirect heat exchange with the charging stock in coils 8 and also in contact with reilux materials passing downwardly through this tower. The

temperature of the vapors at the top of tower I0 is preferably maintained at such a point that substantially all high boiling materials above the boiling point of the gasoline product will be condensed, while the gasoline product in vapor form is conducted from the tower through a vapor line 44.

'I'he vapors conducted through the line 44 are subjected to condensing conditions by passing them in succession through a coil 46 mounted in the lower portion of a stabilizer tower 48, and by indirect cooling in a heat exchanger 49 and in a condenser 58. From the condenser 50 the condensed product and uncondensed gases are conducted through a pipe 52 into a separator 54, in which the uncondensed gases are separated from the pressure distillate product, the latter being conducted through a valved pipe 56, pump 58 and a pipe 60, through the heat exchanger 49 into the tower 48, above the lowermost bubbler tray therein. In the tower 48 the nal product is subjected to a fractionating operation in order to obtain a commercial gasoline having the desired initial and end boiling point by vaporizing the product and withdrawing as residue the material which has a boiling point too high for commercial gasoline. In the furtherance of this stabilizing operation, the heat for producing vaporization in tower 48 is derived from vapors in coil 46 or other auxiliary heating means. The fractionated product is withdrawn through a vapor line 62, condensed in a condenser 64 and collected in a receiver 66. In order to secure the desired temperature at the top of tower 48 a portion of the product may be returned from receiver 66 by means of a pump 68 and pipe 10. The residue from the pressure distillate treated in tower 48 is removed through a valved pipe 'l2 and may be added to the oil introduced as charging stock for coil 22, or introduced directly into line 32. The final gasoline product may be withdrawn from receiver 66 through a valved pipe 14. Uncondensed gas separated in receiver 66 is discharged through a line 15.

'I'he charging stock for the pipe coil 22 used for producing vapors to be cracked in tube bank 34 comprises the reflux condensate collected in the lower portion of the tower I8 and any additional stock of similar boiling point range. This material is conducted through the pipes i6 and I8 in the manner described in connection with the initiating operation.

The uncondensable gas separated in receiver 54 is removed through lines 16 and 18, from the latter of which the gas is distributed to various parts of the apparatus and any excess gas removed through a line 18. For example, gas is used for stripping reux condensate in tower l0 by passing the reflux condensate from the lowermost tray into a stripping section 88 into which gas is introduced by means of a pump 82 and pipe 84 for purpose of stripping out the lower boiling point materials contained in the reflux prior to conducting it to the coil 22.

The body of oil separated in chamber 28 is also preferably stripped with uncondensable gas which, is conducted through apipe 86, pump 88 and valved pipes 90 and 92 into distributors 94 mounted in chamber 28. The gas introduced into the oil in chamber 28 causes substantial vaporization of constituents which have been heated in coil 22, but remain unvaporized. This stripping produces a mixture of oil vapors having boiling points within the range of gas oil and At 200 At 250 Const1tuents pounds pounds Methane and hydrogen 73.3 75.6 Ethane and ethylene 17. 9 18. 0 Propane and propylenes.. G. 8 5. G Butane and butylenes 2.0 0.8

The gas usually contains about 19% of unsaturated compounds and about 8% free hydrogen.

In addition to introducing gas into the body of oil in chamber 28 through the distributors 94, gas may be also introduced into coil 22 through a valved inlet line which connects with the gas line 80.

Since the gas contains a substantial proportion of hydrogen and a very substantial proportion of unsaturated low boiling point hydrocarbons, its presence with the vapors being cracked under the high temperature conditions of tube bank 34 causes a very beneficial action. It has been noted for example that the product obtained from this process has a comparatively low gum content when it is considered that a substantial amount of the cracking is carried out at high temperature or in vapor phase. This low gum content may be attributed to some chemical reactions or changes which may take place in tube bank 34, causing a saturation of the dioleiin hydrocarbons which normally tend to produce gums. It appears that the more unsaturated hydrocarbcns produced in the high temperature cracking operation take up the hydrogen in preference to that of certain other unsaturated compounds such as the normal oleiins and aromatics. This operation therefore utilizes a substantial amount of the uncondensable gas usually produced in the cracking operation, and at the same time produces a motor fuel product relatively low in gum when compared with its high antiknock properties.

The cracking operation in chamber 38 may also be furthered by the introduction of gas through valved pipe 86 and distributor elements 98. The gas introduced into the chamber 38 may not be polymerized to the extent that it is in coils 34, but it nevertheless has the effect of partially saturating certain of the more unsaturated heavy products which produce gums and coke-forming materials.

The unvaporized stripped oil gradually collected in separating chamber 28 is conducted therefrom through pipe 30 and the connecting valved pipe 88, the latter of which connects at an acute angle with the pipe 35 so that the vapors from coil 34 may be used to distribute the oil from chamber 28 into the body of oil in chamber 38. The oil in this latter body is preferably maintained with such a low carbon residue content that substantially no coking will occur. This is accomplished by withdrawing unvaporized residue from chamber 38 through a valved line l2 under a reduced pressure to produce substantial distillation in a concentrator |04. Because of the high temperature of the oil introduced into the chamber I 04, and the substantially lower pressure than that maintained in chamber 38, 50% or more of the oil is vaporized and conducted through a vapor outlet |06 into a reflux tower section |08 in which the vaporized materials are substantially all condensed. Any

vuncondensed material such as a pressure distillate fraction is conducted through a vapor line H0, condensed in condenser H2 and collected in a receiver I|4. Unvaporized residue in chamber |04 is withdrawn through a valved outlet line H8. Cold condensate from receiver H4 is conducted by means of a line II'I and a pump II9 into tower |08 to effect the condensation therein. Oil residue from chamber 20 .may be passed through lines 30 and |02 to concentrator |04.

The distillate collected in tower section |08 is withdrawn and forced by means of pump H8 through a valved pipe |20 and valved pipe I4 into the lower portion of reux tower I0. This distillate may vary somewhat in gravity but usually comprises a substantially high boiling point gas oil which is mingled with the reflux in tower I0 and charged to the Vaporizing coils 22. If the distillate is too heavy for cracking in coil 34, all or any portion thereof may be introduced through line 40 into chamber 38. This method of treating the heavy residue material in the cracking system continuously eliminates the refractory high boiling constituents which are difficult to crack and also eliminates such coke-forming materials which if left in chamber 38 would cause a very substantial deposition. of coke therein. The coke suspended in the oil therefore is continuously removed from the system and the charging stock is not diluted with heavy refractory constituents which are difficult to crack and which would under the conditions, substantially reduce the capacity of the apparatus.

The oil introduced into the coil 22 by pump 20 is supplied under a pressure of about 1000 pounds per square inch, and the pressure maintained in chamber 28 is sufliciently high to provide a pressure in line 32 of approximately 200- 500 pounds per square inch. The resistance to flow in coil 34 naturally causes a substantial decrease in pressure in the outlet line 38 even though the oil constituents are in vapor phase. The products heated in coil 34 are discharged into chamber 38 in which a pressure is maintained of from 250 to 300 pounds per square inch. This pressure may also be maintained throughout the subsequent elements of the apparatus down to and including receiver 54 so that the pressure distillate product condensed in condenser 50 will contain substantially all of the gasoline materials desirable in the final product as well as some absorbed gas which is removed in tower 48. The pressure maintained in chambers I 04 and |08 is substantially lower than that maintained in chamber 38 or from approximately 50 pounds per square inch down to atmospheric pressure, or down to 10 mm. hg.

rlhe cracking temperature maintained in chamber 38 may vary according to the type of charging stock introduced thereinto since as statedabove, a heavy fuel oil residue cracks at a much lower temperature than a stock such as heavy gas oil. In any case a temperature of 750 F. is maintained, and for heavy gas oil a temperature of about 815 is used. The stock treated in chamber 38 comprises any residue removed from chamber 28 as well as the stock introduced through line 40. Since the quantity of material discharged from chamber 28 to chamber 38 is known, the desired quantity of a suitable feed stock may be introduced through feed line 2 which will give a desired composite stock in chamber 38.

' The furnace 24 is constructed more or less after the order of the usual pipe still furnace except that it comprises the two separate coils 22 and 34, the latter of which may comprise two or more rows of tubes under the entire roof of the furnace. This tube bank preferably comprises a coil of sufficient length to complete the cracking of the vapors and arranged so that vapors introduced through line 32 are more or less suddenly raised to the cracking temperature and then maintained at such temperature throughout substantially the entire length of the coil. This provides a time reaction period for the high temperature cracking operation and yields a low boiling product relatively high in aromatic constituents and of a much more stable nature than otherwise would be the case.

The temperature in the combustion chamber of furnace 24 may be maintained substantially constant and the relative temperatures to which the materials in coils 22 and 34 are heated, controlled by varying the relative quantities and composition of the material supplied thereto, and by varying the extent of vaporization in coil 22. The quantity of vapors suppliedto coil 34 may be increased by increasingthe proportion of gas introduced into the oil in chamber 28 or by increasing the Vaporization in coil 22. This vaporization may be increased and controlled by decreasing the oil supply or by introducing a regulated proportion of gas to the coil through line 95. The temperatures obtained in and the amount of heat absorbed by the coils 22 and 34 may therefore be balanced and controlled by regulating the amount of gas supplied through lines 92 and 95. The greater the degree of vaporization in coil 22 the greater the hea-t absorbed. Separate furnaces may be used for coils 22 and 34.

Under certain conditions the charging stock supplied through the line I2 may contain varying proportions of reflux and gasoline material. In such a case the oil is preferably supplied onto the second tray in the column I0 through lines I3 and 39 by proper setting of the valves. Similarly the concentrator distillate passed through line |20 may contain low boiling constituents in which case the distillate may be passed through lines I2! and 39 onto the Second tray in tower I0. Such oils will then ow into stripper where the gasoline constituents will be removed. Oil from the line I2 or distillate from the line |20 may be passed into chamber 38 or tower I0 without interfering with each other, by proper manipulation of the valves in pipes I3. I4. 39, 40, and |2I. When both of these stocks go to the tower I0, the charge for chamber 38 will comprise the unvaporized oil from chamber 28.

The process of the present invention provides a very flexible operation in Vwhich any type of charging stock may be utilized. For example, a very heavy charging stock may be introduced from which is derived a relatively low boiling point stock to be subjected to high cracking temperature. Likewise a relatively low boiling point stock such as gas oil or kerosene may be passed directly through lines I2, I4, I8, and I8 and the unvaporized residue in chamber 28 used for cracking in chamber 38 at a relatively low temperature. In this latter case the high temperature cracking operation would carry out the major part of the cracking unless an independent higher boiling stock is also introduced into chamber 38.

Having thus described the invention, what is claimed as new is:

1. The process of converting petroleum oils into gasoline-like products, which comprises passing an oil distillate charging stock in a conned stream through a heating zone and heating the oil therein to a temperature suflicient to vaporize substantial portions thereof, passing the mixture of liquid and vapor constituents into a separating zone in which vapors are separated from unvaporized oil constituents, passing the vapors so separated into a high temperature cracking zone, and therein subjecting them to a cracking temperature for a substantial period of time, passing the resulting highly heated products into an enlarged cracking chamber in intimate contact with a body of relatively heavy hydrocarbon oil maintained under a pressure of approximately 250 pounds per square inch, to heat and crack the oil of said body, subjecting vapors produced from said cracking operations to redux condensing conditions to produce a reflux condensate, withdrawing unvaporized residue from said enlarged cracking zone into a distilling zone under a substantially reduced pressure whereby substantial portions of said unvaporized residue are vaporized, collecting the distillate from the vapors produced from said residue, mixing it with said reiiux condensate, passing the resulting mixture to said heating zone to supply at least in part said distillate, and separating a gasoline-like product from the vapors remaining uncondensed in the reux condensing operation.

2. The process of converting petroleum oils into gasoline-like products, which comprises passing an oil distillate charging stock in a confined stream through a heating zone and heating the oil therein to a temperature sulicient only to vaporize substantial portions thereof, passing the resulting mixture of liquid and vapor constituents into a separating zone in which vapors are separated from unvaporized oil, passing the vapors from said separating zone into a high temperature cracking zone and therein subjecting them to a cracking temperature for a substantial period of time, passing the resulting highly heated products into an enlarged cracking chamber in intimate contact with a body of relatively heavy hydrocarbon oil maintained under a pressure of approximately 250 pounds per square inch to heat and crack the oil of said body, introducing non-condensable gas into the unvaporized oil in said separating zone and into the oil stream in said iirst-mentioned heating zone, and controlling the relative amounts of gas introduced into said separating zone and said first-mentioned heatlng zone thereby to regulate the temperature to which the oil constituents are heated in said firstmentioned heating zone and said cracking zone, removing the cracked vapor products from the enlarged cracking chamber, fractionating the same and separating a gasoline-like product therefrom.

3. The process of converting petroleum oils into gasoline-like products, which comprises passing a reflux condensate oil produced in a cracking operation and relatively free of gasoline constituents in a confined stream of restricted cross section through a heating zone under a relatively high superatmospheric pressure, heating the oil in said zone to a temperature sufficient to vaporize substantial portions of its constituents, passing the resulting mixture of vapor and liquid oil constituents from said heating zone into a vapor separating zone, separating vapors from unvaporized liquid oil constituents in said separating zone and passing the thus separated vapors therefrom into a high temperature cracking zone in which the vapors are heated in a stream of restricted cross section at a pressure above 250 pounds per square inch and cracked at a temperature of from 950 to 1050 F., passing a mixture of gases derived from the cracking operation into intimate contact with the unvaporized liquid oil in said separating Zone to vaporize an additional portion thereof and passing the resulting mixture of vapors and gases With said separated vapors through said cracking zone, passing the high temperature vapors from said cracking Zone into intimate contact with an enlarged body of relatively high boiling point oil maintained under a pressure of approximately 250 pounds per square inch in a second cracking zone to supply the entire heat necessary for cracking said high boiling point oil, conducting the cracked vapor products from said second cracking zone and separating a gasoline-like product therefrom.

4. The process of converting petroleum oils into gasoline-like products, which comprises passing a reflux condensate oil which is relatively free of gasoline constituents in a confined stream of restricted cross section through a heating zone under a relatively high superatmospheric pressure, heating the oil of said stream in said zone to a temperature suiiicient to vaporize substantial portions of its constituents, passing the resulting mixture of vapors and liquid oil constituents from said heating zone into a vapor separating zone in which vaporsI are separated from unvaporized liquid oil constituents, passing the thus separated vapors from said separating zone into a high temperature cracking zone in which the vapors are heated and cracked in a confined stream of restricted cross section at a temperature of from 950 to 1050 F., passing a mixture of gases derived from the cracking operation into intimate contact with the unvaporized liquid oil in said separating zone to vaporize a further portion thereof, and passing the resulting mixture of gases and vapors with said separated vapors through said cracking zone, passing the high temperature vapors from said cracking zone into intimate Contact with relatively high boiling point oil of higher boiling point than said reflux condensate in a second cracking zone to supply the entire heat necessary for cracking said high boiling point oil, passing unvaporized liquid oil constituents from said separating zone into said second cracking zone to be cracked therein, conducting the cracked vapor products from said second cracking zone and separating a gasoline-like product therefrom.

5. The process of converting petroleum oils into gasoline-like products, which comprises subjecting the vapors produced in a cracking operation to reiiux condensation in a reflux condensing Zone, collecting the reliux condensate from said vapors and passing it through a heating Zone in a stream of restricted cross section under a relatively high superatmospheric pressure, heating the said condensate of said stream in said heating zone to a temperature sufficient to vaporize substantial portions of its constituents, passing the resulting mixture of vapors and liquid from said heating zone into a vapor separating Zone, separating vapors fromunvaporized liquid oil constituents in said separating zone, subjecting the thus separated vapors to a high temperature cracking operation while passing in a confined stream of restricted cross section at a pressure in excess of 250 pounds per square inch in a cracking zone, introducing gas produced in the cracking operation into intimate contact with the liquid unvaporized residue in said separating zone to effect the Vaporization of a further portion thereof, passing the resulting mixture of vapor and gas with the said separated vapors into said high temperature cracking Zone, passing the high temperature cracked vapor product from said cracking zone into intimate contact with an enlarged liquid body of relatively high boiling point oil of higher boiling point than said reilux condensate maintained under a pressure of approximately 250 pounds per square inch in a second cracking zone to supply the entire heat necessary for cracking said high boiling point oil, passing unvaporized liquid oil constituents from said separating Zone into said second cracking zone, passing the resulting vapors derived from the combined cracking operations into said reflux condensing zone, and separating a gasoline-like product from the vapors remaining uncondensed in the reflux condensing zone.

6. The process of converting petroleum oils into gasoline-like products, which comprises passing a relatively high boiling point oil stock in a conned stream of restricted cross section through a reflux condensing zone in indirect heat exchange with vapors produced in the converting operation, passing the charging stock preheated in said heat exchange into an enlarged cracking zone in Which an enlarged liquid body of such oil is heated under a pressure of at least approximately 250 pounds per square inch and maintained at a cracking temperature, collecting a reflux condensate from the vapors treated in said reflux condensing zone, heating the resulting reiiux condensate to a temperature sucient to vaporize substantial portions of its constituents but not to a temperature sufficient to vaporize higher boiling coke-forming constituents contained therein, conducting the heated mixture of vapors and liquid reflux condensate from said reflux condensate heating operation'into a vapor liquid separating Zone and therein separating the vapors from unvaporized liquid oil, cracking the thus separated vapors from said separating Zone at a temperature of from 950 to 1050 F. in a second high temperature cracking Zone in which said vapors are heated in a stream of restricted cross section by indirect heat exchange With a high temperature heating medium, mingling cracking still gases with the vapors in said second high temperature cracking zone, passing the resulting highly heated products from said second cracking Zone into intimate contact with the high boiling point oil introduced into said enlarged cracking zone to supply the entire heat and temperature necessary for cracking and distilling the oil therein, passing the combined cracked vapors from said enlarged cracking zone into said reflux condensing zone, and separating a gasoline-like product from the vapors remaining uncondensed in said reilux condensing Zone.

7. The process of converting petroleum oils into gasoline-like products, which comprises passing an oil distillate which is relatively free of gasoline constituents in a conned stream of restricted cross section through a heating zone in which the oil distillate is heated to a temperature suflicient to vaporize a substantial proportion of its constituents, passing the resulting mixture of vapor and liquid oil constituents from said heating zone into a vapor separating Zone and therein separating the vapors formed by said heating from the liquid oil constituents, passing the separated vapors from the separating `Zone into a high temperature cracking Zone in which they are heated in a conned stream of restricted cross section to a cracking temperature of approximately l000 F. and cracked, conducting the resulting highly heated cracked products resulting from the heating and cracking in said cracking Zone into a second cracking Zone in intimate contact with an enlarged liquid body of a relatively heavier hydrocarbon oil introduced thereinto, and cracking said heavier hydrocarbon oil solely by the heat and temperature contained in said highly heated cracked products, separately introducing a gas containing hydrogen and unsaturated hydrocarbons directly into intimate contact with the enlarged body of oil in said second cracking Zone to aid in the conversion of the oil introduced thereinto, fractionating the vapors produced in the combined cracking operations and recovering a iinal gasoline-like product suitable as a motor fuel therefrom.

8. In the process of converting mineral oils to oils suitable as gasoline motor fuel in which an oil charging stock is passed in a confined stream of restricted cross section through a heating coil mounted in a furnace and therein heated to a temperature suiicient to vaporize a substantial portion thereof, the improvement which comprises conducting the resulting mixture of vapor and liquid oil constituents from said coil into a separating zone in which vapors are separated from unvaporized liquid oil constituents, conducting the resulting separated vapors from said separating zone in a conned stream of restricted cross section through a separate heating coil mounted in said furnace and therein heating and cracking the vapors at a relatively high cracking temperature, introducing noncondensable gases into said rst-mentioned coil to increase the vaporization of the oil passed therethrough and thereby increase heat absorption, controlling the temperature to which the oil constituents are heated in each coil by regulating the amount of gas introduced into said rst-mentioned coil thereby regulating in turn the amount of vapori- Zation and consequent heat absorption in said rst-mentioned coil and the amount of vapor to be heated in the second heating coil, fractionating the cracked vapors resulting from the cracking operation and separating a gasoline-like motor fuel product therefrom.

9. The process of converting petroleum oils into gasoline-like products, Which comprises heating an oil to a temperature sufcient to vaporize a substantial portion thereof, conducting the resulting heated mixture of liquid and vapor products into a vapor-liquid separating zone in which the vapors are separated from the unvaporized liquid oil constituents, passing the separated vapors from said separating zone in a stream of restricted cross section through a heating Zone in which the vapors are heated to a temperature sufficiently high to crack a high boiling point hydrocarbon oil to produce gasoline-like constituents, passing the resulting highly heated products from said heating zone into the lower portion of an enlarged vertical cracking zone and fractionating the same and recovering gasolinelike constituents therefrom.

10. The process dened by claim 9 in which a heavy hydrocarbon oil is preheated and introduced into said enlarged cracking zone and therein cracked into gasoline-like products in intimate contact With the highly heated products introduced thereinto and which comprise the sole heating means for heating and cracking said heavy hydrocarbon oil.

DAVID G. BRANDT.

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