US1936735A - Process for converting hydrocarbon oils - Google Patents

Description

Nov. 28, 1933- R. DE TAVEAU PROCESS FOR CONVERTING HYDROCARBON OILS Fild March 30, 1922 IN V EN TOR.

ATTORNEY By M Patented Nov. 28, 1933 UNITED STATES PROCESS FGR CQNVERTING is:

CARBON @ILS Ren de M. Taveau, Elizabeth, N. 3., assignor, by mesne assignments, to The Texas @ompany, New York, N. Y., a corporation of Delaware Application March 30, 1922. Serial No. 541945 30 (Claims.

This invention relates to the conversion under pressure of high boiling hydrocarbon oil into lower boiling products, and it has special reference to a process and apparatus for effecting the conversion in a combined vapor-liquid phase.

One of the objects of the present invention is to provide a process and apparatus of the character above indicated, which shall combine the respective advantages of vapor phase and liquid phase cracking operations, which shall be simple, efficient and reliable in operation, shall be particularly economical in' heat consumption, and which shall avoid the dangers and disadvantages of the heavy deposition of carbon incident to the usual cracking operations.

In vapor phase cracking processes, such as typified, for example, by the Hall process, it is desirable in order to avoid excessive deposition of carbon to supply a relatively clean distillate to the vapor phase converter and to this end it is good practice to subject the oil to be treated to a preliminary distillation process to remove impurities. Moreover, the conduct of a vapor phase cracking process along the lines of the Hall process is accompanied by excessive heat losses, resulting from the waste heat of the high temperature cracked and uncracked vapors evolved in and emerging from the converter.

It is another object of the present invention, therefore, to provide a combined vapor-liquid phase cracking process and apparatus in which the heat of the vapors evolved in the vapor phase cracking operation is conserved and subsequently utilized to raise and maintain a body of oil in an unheated heat-insulated still at a cracking temperature, whereby the oil contained therein is converted in the liquid phase.

Another object of the invention is to separate out from the evolved vapors resulting from the combined vapor phaseand liquid phase cracking,

operations the lighter constituents and to return to the vapor phase converter the heavier constituents which by reason of the treatment which they have undergone in the converter and the still possess suitable characteristics to enable them to be used as the supply of oil for the vapor phase cracking operation, thereby avoiding the necessity of the usual preliminary distillation. The process, therefore, operates to supply oil of the requisite character for its own operation in the vapor phase stage.

A further object of the invention is to provide a process which upon attaining its normal running condition, the heavier constituents of the evolved vapors are utilized to replace, in part or in whole, the supply of distilled oil necessary for the operation of the vapor phase cracking while the operation as a whole is being initiated. I

A still further object of my invention is to iniprove the quality of the final product, which, ac-

(ci. l9666) cording to my present belief, is attained by caus= ing the cracked products of the vapor phase op== eration to mingle and chemically react with the cracked products of the liquid. phase operation.

These and other objects of the invention and features by means of which they are attained will be more fully understood from the following description of the process in connection with the preferred embodiment of the apparatus illustrated in the accompanying drawing, in which Fig. 1 is a diagrammatic view of an apparatus or system constructed in accordance with the present invention and adapted for practicing my improved cracking process, and

Fig. 2 is a sectional view on the section line 22 of Fig. 1.

Referring to the drawing, the system shown comprises, in general, a still 10 adapted to receive a body of heavy oil; a heater 12 for preheating the initial body of oil before it is introduced into the still 10; a converter M, preferably comprising an elongated cracking coil or a tube of restricted cross section, and adapted to crack the oil supplied thereto in the vapor phase and to deliver the highly heated evolved vapors into the body of oil in the still 10, whereby said oil is maintained at a sufficient cracking temperature to efiect the conversion of the oil in the liquid phase; a separator or fractionating device 16 for receiving the evolved vapors from the combined vapor phase and liquid phase cracking op erations and selectively condensing out the heavier constituents thereof and allowing the lighter constituents of desired volatility to pass on; a condenser 18 for condensing the lighter constituents of the vapors; a collecting tank 20 for receiving the ultimate light distillate; a cooling apparatus 22 for cooling the heavier condensate withdrawn from the separator 16, and a collecting tank 24 for-receiving the condensate so cooled.

The still 10 is made of any suitable construction and is heat-insulated by means of a lagging 30. The still is provided with a liquid level gage 31, an overflow pipe 32and a residue drawoff 33. The still is unheated'externallyand the body of oil contained therein receives its heat solely from the vapors evolved in the vapor phase cracking converter 14, which vapors are conducted by means of a heat-insulated pipe 34 from said converter and delivered in the lower part of the still 10 beneath a false bottom 35, conveniently comprising a plurality of sheet iron plates or the like. These plates, which rest at their opposite edges upon the walls bf the still and are slightly spaced apart, serve the purpose of distributing the hot vapors delivered through the vapor line 34 so as to bring them into intimate contact with the oil in the still.

The preheater 12 may be of any desired construction and, as shown, comprises an elongated coil of restricted cross section that is heated by the products of combustion from a suitable furnace 37 disposed below it. This preheater is connected by means of a pipe 38 having a valve 39 with the bottom of the still 10 and is supplied with a heavy oil, such for instance as crude paraifine gas oil from a suitable source through pipe 40 by means of a pump 41 that is connected to the preheater by a pipe 42 provided with a valve 43. The preheater 12 is utilized only to supply the initial body of preheated oil to the still.

The vapor phase converter 14 may be of any type-suitable for vapor phase conversion and is preferably similar in construction to that of the preheater 12 and comprises an elongated coil 45 of restricted cross section that is highly heated ,by means of a furnace 46 disposed below it. This converter 14 is supplied under pressure with oil of a suitable character from a convenient source through pipe 47, pump 48, pipe 49 provided with a valve 50, a pipe 51, preheater 52 and pipe 53. For vapor phase conversion, the oil must be relatively clean and, therefore, a preliminary distillation of a suitable oil, as for instance-a paraffin gas oil, is resorted to, in

order to produce an oil of desirable characteristics for this purpose. The preheater 52 may be heated directly or indirectly, in any manner known to the art. As the oil is forced under pressure through the cracking coil 45 at a rapid rate it is subjected to high cracking temperatures in the neighborhood of from 500-600 C. and is cracked in the vapor phase.

The conversion operation is not restricted to these temperatures and may vary therefrom to a considerable extent, depending upon the character of the oil being treated and other operating conditions. The vapors and gas in the cracking coil 45, including the converted and unconverted vapors, emerge therefrom at high temperatures and are conducted through the heatinsulated pipe 34 and valve 54 and delivered directly, into the body of the oil in the still 10. The heat of the vapors and gas, thus introduced into the still, are utilized to raise and maintain the body of heavy oil therein at a sufficient cracking temperature to effect the conversion of the oil in the liquid phase, without the necessity of supplying external heat to the still. The temperature of the still, after the operation of the system has been initiated, is maintained at from 700-800 F., although it may vary therefrom.

The vapors evolved from the liquid phase cracking operation in the still, together with those of the vapor phase cracking operation in the converter 14, are withdrawn from the still through a vapor line 56 and are conducted to the separator or fractionator 16. This separator or fractionator 16 is enveloped by heat-insulated casing or jacket 57 through which either a cooling or a heating medium is circulated by means of the pipes 58 and 59 for the purpose of maintaining the desired temperature to eifect whatever selective condensation and consequent separation of the constituents of the evolved vapors as may be determined upon. The lighter uncondensed vaporous constituents of desired volatility emerge from the upper end of the separator 16 and pass through a pipe 61 into a coil 62 comprising a part of the water cooled condenser 18, in which the vapors are condensed. The condensed light distillate is then discharged and collected in the receiving tank 20, having a gas outlet 63 controlled by valve 64 and a distillate discharge outlet 65 regulated by a valve 66.

The heavier constituents of the vapors evolved from the combined vapor-liquid phase cracking operations are condensed in the separator 16 and may be conducted through pipe 67 having a valve 68 and thence through a coil 69 of the water cooled cooler 22, after which it passes through the valve 70 and is collected in the receiving tank 24. The character of the condensate or light residue collected in the tank 24 is such that it may be utilized as the oil supply for the converter 14 for the vapor phase conversion. Therefore, means is provided for returning this condensate and delivering it to the converter 14 for retreatment. This means includes the valve 73, pipe 74, pipe 75, pump 76, pipe 77, and valve 78, whereby the condensate is returned to the converter through the preheater 52. After the process has been initiated and this condensate is produced and collected in suflicient quantities, it may be utilized to entirely replace the distillate originally supplied to the converter 14 through the pipe 47 and pump 48. In this way, the process, after being brought up to normal operating conditions, produces its own supply of oil of a character suitable for the vapor phase cracking operation so that the auxiliary supply of clean distillate may be required only for starting the operation and may thereafter be discontinued. Provided the quantities of clean light residue or condensate are insuificient to supply the requisite amount of oil for the vapor phase cracking operation, it may still be necessary to deliver a restricted quantity of preliminarily cleaned distillate to the converter 14.

In place of abstracting the heat of the heavy condensate by means of the cooler 22, the valves 68 and 73 may be closed, and the valve opened, to permit the condensate, in heated condition, to pass through the pipe 81 and into a collecting tank 82 from whence it.is withdrawn through pipe 83 and thence through pipe 75 by means of pump 76 which delivers it through the preheater 52 to the converter 14. In this way the heat of the condensate is largely retained and conserved, thereby creating a heat cycle and contributing to the heat-efliciency of the system as a whole.

The separator or fractionator 16 includes a preheating or heat-exchanger coil 85, through which heavy oil from pipe 40 and pump 41 is delivered to the still 10 after the system is brought up to normal operating conditions. This is effected by closing the valve 43 and opening valve 86 in pipe 87 whereby the pLunp 41 supplies the heavy oil to be operated upon through the pipe 87 and thence through the preheating or heat-exchanger coil from which the oil is conducted to the still through a pipe 90 disposed within the vapor line 56. The supply of oil is thus subjected to the heat of the escaping vapors evolved from the combined vapor-liquid phase conversion operations and is thus preheated before being delivered into the still near the bottom thereof.

By suitably controlling the pressure valve 64, the entire system may be operated under any desired super-atmospheric pressure which is pref erably in the neighborhood of from 75 to 100 lbs., although it may vary below or above this range, if desirable or necessary.

The operation of the system is briefly as follows:

The still 10 is first filled with a heavy oil such as crude paraifin gas oil, to the desired level by means of the pump 41 which forces the oil through the preheater 12 in which the oil is raised to a temperature of from 400-500 F. or thereabouts. Having supplied the necessary volume of oil to the still 10, the operation of the pump ll and preheater 12 is discontinued and the valves 39 and 43 closed.

Thereafter the vapor phase converter 14 is put into operation and the pump 48 is utilized to deliver a suitable clean distillate, such for example as redistilled paraflin gas oil, from a suitable source through the preheater 52 to the converter 14, in which the oil is cracked under pressure at high temperatures in the vapor phase and the evolved vapors and gas delivered in highly heated condition into the body of oil in the still 10. I have found that distillate may be satisfactorily supplied to a converter composed of 1" pipe at a rate of from 2 or 3 gallons per minute. The system is operated in this manner for a period sufficiently long to enable the temperature of the body of oil in the heat-insulated still 10 to be gradually raised to the desired liquid phase cracking temperature, after which liquid phase conversion of the heavy oil inthe still 10 takes place. Under those conditions, additional heavy oil may be supplied to the still by means of the pump 41 through the pipe 87 and preheater or heat exchanger coil 85, through the agency of which the charging oil is preliminarily heated by the escaping vapors.

After the system has been brought up to normal operating conditions, I have found that good results are secured by supplying heavy oil to the still 10 in the neighborhood of from 2 to 3 gallons per minute. Ordinarily this supply may be continuous, although operating conditions may be such as to make it desirable to introduce the preheated heavy oil intermittently.

The preferred mode of operation of this system is to eifect a predominating amount of liquid phase conversion in the still 10, which, by reason of the fact that the still is unheated, depends upon the amount of heat supplied thereto from the vapors evolved in the vapor phase cracking converter it. It is, however, desirable to operate the vapor phase converter 14 at a relatively low cracking temperature, while still having it supply suficient heat to the still to maintain the desired degree of liquid phase conversion.

Moreover, it is my present belief that the characteristics of the ultimate distillate are considerably improved by reason of the intermingling of the vapors of the vapor phase and liquid phase cracking operations which are believed to react chemically the one with the other to this end.

The selective separation or fractionation of the lighter and heavier constituents of the combined vapors is regulated by suitably controlling the temperature of the separator 16 so as to allow only those light vapors of desired volatility to pass over into the condenser 18 and distillate collecting tank 20. As already explained, the light residue or condensate withdrawn from the separator or fractionator 16 is, by reason of its previous treatment either in the vapor phase converter 14 or liquid phase still 10, of a character suitable to be returned and to constitute either, in whole or in part, the supply of oil for the vapor phase cracking operation. This is a feature of importance inasmuch as it obviates the necessity of an extended preliminary distillation heretofore required in producing a clean oil for the vapor phase converting operation.

Another feature of importance resides in the fact that the conversion in the liquid phase is conducted in a still which is not subjected to external heat but which is heated internally solely by the heat derived from the vapors of the vapor phase cracking operation. This results in obviating, to a large extent, the dangers of a heavy incrustation or deposition of carbon on the still bottom, inasmuch as the deposition of carbon is greatly reduced, and, moreover, the character of whatever carbon is deposited is such that it may usually be withdrawn through the residue draw-off 33 with facility. This removal of carbon and other heavy residuums from the still may be continuous or intermittent as found necessary or desirable.

In a modified aspect of the invention I contemplate the utilization of the still 10 merely as a vaporizing chamber in which the pressure may be considerably reduced from that of the vapor phase cracking converter 14 or may, in certain instances, be maintained at atmospheric pressure. In accordance with this modified mode of operation, no material amount of liquid phase conversion will take place but the still 10 will function mainly as a vaporizer, from which the vapors are removed to the separator 16 where the desired selective separation is effected. The heavier constituents of the vapors are drawn oil and, being of suitable character, are returned to the converter 14 to supply the requisite oil for the vapor phase cracking operation. The

system is thus operated in such manner as to provide its own supply of oil for the vapor phase conversion, thereby eliminating the usual preliminary step of redistillation, commonly employed for the purpose of producing a clean quality of oil to be cracked in the vapor phase.

Having thus described, in more or less detail, the nature and character of the present invention as exemplified in the illustrated embodiment thereof, it should be understood that various modifications in the apparatus and the mode of operation may be effected without departing from the spirit and scope of the invention defined in the appended claims.

I claim:

l. The process of converting high boiling hydrocarbon oils into lower boiling products which comprises passing the oil through a converter maintained at a sufiicient cracking pressure and temperature to convert the oil in the vapor phase, maintaining a body of oil under pressure in an unheated still, delivering the products from the converter into the body of oil in the still whereby said oil is maintained at a cracking temperature and the oil converted in the liquid phase, separating out the lighter constituents of the evolved vapors and returning the heavier constituents thereof to the converter for retreatment.

2. The process of converting high boiling hydrocarbon oils into lower boiling products which comprises cracking a body of oil in the vapor phase, maintaining a body of oil in an unheated still, delivering the products of the vapor phase cracking operation into the body of oil in the still to maintain said oil at a cracking temperature and to effect the cracking of the oil in the liquid phase, delivering the evolved vapors from both the vapor phase and the liquid phase operations to a separator, separating out the lighter constituents thereof and back-trapping the heavier constit- Mill uents to supply oil for the vapor phase cracking operation.

3. The process of converting high boiling hydrocarbon oils into lower boiling products which comprises continuously delivering a suitable distillate to a vapor phase converter, continuously delivering a heavy oil to an unheated still, delivering the evolved vapors of the converter into the body of oil in theistill whereby said oil is maintained at a cracking temperature suificient for liquid phase cracking, removing from the still the evolved vapors of both the liquid phase and vapor" phase operations, separating out the lighter constituents thereof and continuously returning the heavier constituents to the converter to supply oil to be cracked therein.

4. The process of converting high boiling hydrocarbon oils into lower boiling products which comprises preheating a heavy oil and delivering it to an unheated still to maintain a body of oil' therein, subsequently cracking a clean distillate in the vapor phase, delivering the products of the cracking operation into the body of oil in said still to maintain a sufiicient cracking temperature therein to effect a liquid phase cracking thereof, taking off the evolved vapors from the still, separating out the lighter constituents thereof, discontinuing the supply of distillate for the vapor phase cracking operation and returning the heavier constituents of the evolved vapors for the vapor phase operation and subsequently supplying a heavy oil to the still and preheating it by the evolved vapors taken therefrom.

5. The process of converting high boiling hydrocarbon oils into lower boiling products which comprises delivering a heavy oil to a still to supply an initial body of oil thereto, delivering a suitable distillate to a cracking coil where it is cracked in the vapor phase at high cracking temperatures and pressures, discharging the evolved vapors into the body of oil in the still to maintain said body temperature and pressure to eifect the cracking of the oil in the liquid phase, taking oif the evolved vapors, supplying a heavy oil to the still, preheating it by the evolved vapors taken therefrom, separating out the lighter constituents of the evolved vapors and returning the heavier constituents to the vapor phase cracking coil to replace, in whole or in part, the distillate initially supplied thereto.

6. The process of converting high boiling hydrocarbon oils into lower boiling products which comprises supplying to a converter a suitable distillate to be cracked therein in the vapor phase, supplying a heavy oil to an unheated heat-insulated still, discharging the evolved vapors from the vapor phase cracking operation into the body of oil in the still to maintain a sufiicient temperature therein for liquid phase cracking, separating out the lighter constituents of the vapors evolved in the vapor phase and liquid phase cracking operations and returning the heavier constit uents directly and while still in heated condition to the converter to serve as a suitable distillate for the vapor phase cracking operation.

7. A process of cracking heavier hydrocarbons to produce lighter hydrocarbons which consists in internally heating an externally unheated body thereof in liquid-phase to a cracking temperature under pressure, driving oil" the cracked hydrocarbons therefrom, condensing the heavier vapors from said cracked hydrocarbons, separately condensing the lighter vapors, separately heating the condensate from the heavier vapors products which at a sufficient cracking,

to vaporize and crack the same and injecting them into said body of hydrocarbons.

8. A process of cracking heavier hydrocarbons to produce lighter hydrocarbons which consists in internally heating an externally unheated body of heavy hydrocarbons in liquid-phase to a cracking temperature under pressure and distilling the cracked hydrocarbons therefrom, condensing the heavier vapors of the hydrocarbons and heating the condensate from the heavier vapors to a cracking temperature to vaporize and crack the same, injecting the cracked vapors into said body of hydrocarbons and separately condensing the lighter vapors from said body.

9. The process of converting high boiling hydrocarbon oils into lower boiling gasoline-like stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products in the vapor phase under suitable temperature and pressure conditions for the production of gasoline-like products, utilizing the heat of the evolved vapors of the vapor phase cracking operation to supply heat to a body of oil under pressure in a still to maintain the necessary cracking temperature to effect its conversion in the liquid phase, taking ofi from the still the evolved vapors of the combined vapor phase and liquid phase cracking operation, fractionally condensing the vapors to separate out comprises cracking a charging heavier constituents thereof and returning at least a portion of the heavier constituents directly to the vapor phase cracking operation.

10. The combined process of cracking high boiling point oils in liquid and vapor phases, which comprises maintaining a relatively large body of oil in a liquid phase cracking zone under cracking conditions of temperature and pressure, conducting an oil distillate in a confined stream through a heating zone in which it is heated and cracked in vapor phase, passing the resulting cracked vapor products while at a high temperature into said body of oil to heat and crack the same, separating the higher from the lower boiling constituents of the vapors evolved in the cracking operations by fractional condensation, and passing the condensed higher boiling point constituents directly into said heating zone.

11. The process of cracking high boiling point hydrocarbon oils into lower boiling point products, which comprises introducing a high boiling point oil into an enlarged cracking zone in which a body of oil is maintained under cracking conditions of temperature and pressure, cracking an oil distillate in vapor phase at a high temperature, conducting the resulting vapor products while hot into said body to crack the oil therein in liquid phase, passing the vapors evolved in the cracking operations from said zone into a' vapor fractionating zone in which the higher boiling point constituents are condensed, conducting the resulting condensate directly and while lot to supply at least in part the oil distillate for said vapor phase cracking, and preheating the high boiling point oil introduced into said cracking zone by passing it in'heat exchange with hot vapors evolved in the cracking operations.

12. The combined process of cracking high boiling point oils in liquid and vapor phase, which comprises maintaining a relatively large body of, oil in a liquid phase cracking zone under cracking conditions of temperature and pressure, conducting an oil distillate through a heating zone in which it isheated and cracked in vapor phase,

passing the resulting cracked vapor products while at a high temperature into said body of oil to heat and crack the same, separating the higher from the lower boiling constituents of the vapors evolved in the cracking operations by fractional condensation, passing the condensed higher boiling point constituents while hot directly into said heating zone, preheating a high boiling point oil by passing it in heat exchange with vapors evolved in the cracking operations and passing it into said body of oil.

13. The process of converting high boiling point hydrocarbon oils into relatively lower boiling point oils, which comprises supplying a distillate oil only to a vapor phase cracking zone maintained under suitable conditions of temperature and pressure to efiect cracking of the distillate oil in vapor phase, maintaining a body of high boiling point oil under cracking conditions of temperature and pressure in a separate cracking zone, passing the hot cracked vapors from said vapor phase cracking zone into the body of oil in said separate cracking zone, removing the combined evolved vapors from the last mentioned cracking zone, separating the higher boiling point constituents of the vapors from the lower boiling point products, and passing the higher boiling point constituents directly into the vapor phase cracking zone.

14. The process of converting hydrocarbon oils of high boiling point into lower boiling point gasoline-like products, which comprises cracking a body of high boiling point oil in liquid phase, cracking a stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products in vapor phase in a vapor phase cracking zone for the production of gasoline-like products, conducting the vapors evolved in the latter cracking operation in heat exchange with said high boiling oil to maintain it at cracking temperature, subjecting vaporous products from said cracking operations to partial condensation to separate as condensate the higher boiling point constituents from the lower boiling point constituents, passing the separated higher boiling point constituents directly to the vapor phase cracking zone, preheating a high boiling point oil by passing it in heat exchange with hot vapors from said cracking operations and conducting it to supply oil for said liquid phase cracking operation.

15. A process of cracking heavier hydrocarbons to produce lighter hydrocarbons which comprises internally heating a body of liquid oil to a cracking temperature, withdrawing converted vaporous products from said oil body, condensing the heavier vapors from said vaporous products; separately heating condensate of said heavier vapors to vaporize and crack the same in the vapor phase, injecting the highly heated cracked prod ucts into the said body of oil to effect said internal heating and to maintain said oil body at said cracking temperature, continuously passing fresh oil in indirect heat exchange with products of the operation and adding the preheated fresh oil to said oil body, and substantially continuously withdrawing portions of said oil body.

16. The process of converting hydrocarbon oil which comprises subjecting relatively light hydrocarbon oil to cracking conditions of temperature to efiect cracking thereof in the vapor phase, discharging resulting highly heated vaporous products into a body of relatively heavy liquid oil in a separate zone to maintain said oil body at cracking temperature and effect conversion thereof, withdrawing from said body converted vaporous products, subjecting said vapors to fractional condensation, passing resulting condensate to said vapor phase conversion operation as all or part of the charging stock therefor, and substantially continuously supplying additional to said oil body in said separate zone.

1'7. The process of converting hydrocarbon oil which comprises subjecting relatively light hydrocarbon oil to cracking in the vapor phase under conditions of temperature upwards of 500 0., discharging resulting highly heated vaporous products into a body of relatively heavy liquid oil in a separate zone to maintain said oil body at cracking temperature and eifect conversion thereof, separately withdrawingfrom said body converted vaporous products, and subjecting them to fractional condensation, passing resulting condensate to said vapor phase conversion operation as all or part of the charging stock therefor, and substantially continuously supplying additional heavy liquid oil to said body.

18. The process of converting relatively highboiling hydrocarbon oil into gasoline-like products which comprises subjecting charging stock consisting substantially entirely of a relatively light normally liquid hydrocarbon oil heavier than the desired-gasoline-like products to cracking conditions of temperature in the vapor phase for the production of gasoline-like products, passing resulting highly heated vaporous products in heat exchange relation with a body of relatively heavy liquid oil in a separate conversion zone to maintain said oil body at cracking temperature and effect conversion thereof, passing vaporous products from the said oil body to a fractional condensing operation, passing resulting condensatedirectly to said vapor phase cracking operation, and substantially continuously supplying additional liquid oil to said body.

19. The process of converting relatively highboiling hydrocarbon oil into gasoline-like products which comprises subjecting charging stock consisting substantially entirely of 'a relatively light normally liquid hydrocarbon oil heavier than the desired gasoline-like products to cracking conditions of temperature in the vapor phase for the production of gasoline-like products, passing resulting highly heated vaporous products in heat exchange relation with a body of relatively heavy liquid oil in a separate conversion zone to maintain said oil body at cracking temperature and effect conversion thereof, passing vaporous products from the said oil body together with vaporous products of said vapor phase cracking operation to a fractional condensing operation, passing resulting condensatein liquid form to said vapor phase cracking operation, substantially continuously supplying addiof said body and avoiding its passage to said vapor phase cracking operation.

20. The method of converting hydrocarbon oils which comprises preheating a substantially continuously flowing stream of arelatively heavy liquid oil and discharging the preheated stream into an enlarged zone wherein said preheated tional liquid oil to said body and withdrawing oil liquid oil is maintained in a body at cracking temperature, withdrawing cracked vaporous products from said liquid oil body and frictionally condensing them, passing resulting condensate in a flowing stream through a heated zone wherein it is subjected to cracking in the vapor phase, and discharging the stream of heated products from said vapor phase cracking zone into the said body of liquid oil in said enlarged zone to maintain said liquid oil at cracking temperature.

21.- The method of converging hydrocarbon oils which comprises preheating a substantially continuously flowing stream of a relatively heavy liquid oil and discharging the preheated stream into an enlarged zone wherein said preheated liquid oil is maintained in a body at cracking temperature, withdrawing cracked vaporous products from said liquid oil body and fractionally condensing them, passing resulting condensate in a flowing stream through a heated zone wherein it is subjected to cracking in the vapor phase, discharging the stream of heated products from said vapor phase cracking zone into the said body of liquid oil in said enlarged zone to maintain said liquid oil at cracking temperature, and withdrawing liquid residual products from said enlarged zone.

22. The process of converting hydrocarbon oil into lower boiling gasoline-like products which comprises passing a stream of charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products through a heated zone wherein it is subjected to cracking in the vapor phase for the production of gasoline-like products, maintaining in a separate zone a body of a relatively heavy liquid oil at cracking temperature, utilizing the heat of vaporous cracked products from said-heating zone to maintain said liquid body of oil in said second zone at said cracking temperature, separating and withdrawing cracked vaporous products from said zones, fractionally condensing them to form a distillate product suitable as charging stock for said heating zone, and passing said distillate product in liquid form directly to said heated zone.

23. The process of converting hydrocarbon oil into lower boiling gasoline-like products which comprises passing a stream of charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products through a heated zone wherein it is subjected to cracking in the vapor phase for the production of gasoline-like products, maintaining in a separate zone a body of a relatively heavy liquid oil at cracking temperature, utilizing the heat of vaporous cracked products from said heating zone to maintain said liquid body of oil in said second zone at said cracking temperature, and withdrawing cracked vaporous products from said zones, fractionally condensing them to form a distillate product suitable as charging stock for said heating zone, passing said distillate product in liquid form directly to said heated zone, substant ally continuously supplying additional heavy oil to said oil body in the second zone, and substantially continuously withdrawing liquid residual products from said second zone.

24. The process of converting hydrocarbon oil into lowerboiling gasoline-like products which comprises passing a stream of charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products through a heated zone wherein it is subjected to cracking in the vapor phase for the production of gasoline-like products, maintaining in a separate zone a body of a relatively heavy liquid oil at cracking temperature, passing hot vaporous cracked products from said heated zone in contact with said liqud body of oil in said second zone to maintain said oil body at sa d c acki temperature, w thd awi cracked vaporous products from the said separate zone and fractionally condensing them, passing resulting condensate of said vapors in liquid form directly to said heated zone for cracking in the vapor phase, substantially continuously passing fresh heavy liquid oil in indirect heat exchange relation with hot cracked products formed in the process and thereafter passing the preheated fresh oil to said second zone and adding it to the said oil body therein, and substantially continuously withdrawing liquid residual products from said second zone.

25. The process of converting hydrocarbon oil into lower boiling gasoline-like products which comprises passing a stream of charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products through a heated zone wherein it is subjected to cracking in the vapor phase for the production of gasoline-like products, maintaining in a separate zone a body of a relatively heavy liquid oil at cracking temperature, passing hot vaporous cracked products from said heated zone In contact with said liquid body of oil in said second zone to maintain said oil body at said cracking temperature, withdrawing cracked vaporous products from the said separate zone and fractionally condensing them, passing resulting condensate of said vapors in liquid form directly to said heated zone for cracking in the vapor phase, substantially continuously passing fresh heavy liquid oil in indirect heat exchange with hot vaporous products formed in the process, thereafter passing the preheated fresh oil to said second zone and adding it'to said body, and substantially continuously withdrawing liquid residual products from said second zone.

26. The improvement in the art of converting hydrocarbon oils into gasoline-like products which comprises passing a confined stream of charging stock consisting substantially entirely of a normally liquid distillate hydrocarbon oil heavier than the desired once-through an elongated heated zone wherein it is subjected to cracking under superatmospheric pressure for the production of gasolinelike products, passing the stream of hot cracked products from said zone into an externally unheated distilling zone, separating vapors in said distilling zone and passing them to a fractionating zone, continuously passing relatively cool feed stock in indirect heat exchange relation with hot products from said distilling zone, and thereafter discharging the preheated feed stock into direct contact with the stream of hot cracked products entering the said distilling zone whereby crackable constituents are volatilized and said feed stock is raised to a cracking temperature solely by the heat of said stream of hot cracked products, passing said volatilized portions from the said distilling zone to said fractionating zone and therein condensing such crackable constituents, withdrawing such condensate substan tially free from admixture with residual cracked products and unvolatilized feed stock and passing the said condensate in liquid form directly to said cracking zone as charging stock therefor, collecting unvaporized residual products in said distilling zone in a body and maintaining said' body of residual products at a cracking temperature of at least 700 F. by the heat of the said stream of cracked products discharged from said cracking zone into said distilling zone, and withdrawing residual products from said distilling gasoline-like products,

zone and avoiding the passage of any of said residual products to the said cracking zone.

27. The method of converting hydrocarbon oil into gasoline-like products which comprises flowing a stream of charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products once-through an elongated passageway and heating the oil during its flow therethrough to effect its cracking in the vapor phase under superatmospheric pressure for the production of gasoline-like products, discharging the stream of cracked products into a distilling zone, separating vapors in said distilling zone and passing them to a fractionating zone, continuously passing relatively cool feed stock in indirect heat exchange relation with products from said cracking operation, discharging the preheated feed stock into direct contact with the stream of hot cracked products entering the said distilling zone to volatilize crackable constituents, passing volatilized products from the distilling zone to the said fractionating zone and therein conlensing such crackable constituents, withdrawing such condensate substantially free from admixture with residual cracked products and unvolatilized feed stock and passing the said con-- densate in liquid form directly to said cracking zone as charging stock therefor, collecting unvaporized residual products in said distilling zone in a body and maintaining said body at a cracking temperature of at least 700 F. by the heat of the said stream of cracked products discharged from said cracking zone into said distilling zone, and avoiding passing any unvolatilized residual products formed in the process to said cracking zone.

28. The improvement in the art of pyrolytic conversion of hydrocarbons into gasoline-like products which comprises passing a charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products once-through an elongated heated passageway and subjecting it to cracking during its flow therethrough for the production of gasoline-like products, discharging the stream of hot cracked products from said cracking zone into an externally unheated distilling zone, separating vapors in said distilling zone and passing them to a fractionating zone, continuously passing relatively cool feed stock in indirect heat exchange relation with the said separated vapors and thereafter discharging the preheated feed stock into direct contact with the said stream of cracked products entering the said distilling zone whereby crackable constituents are volatilized and said feed stock is raised to a cracking temperature solely by the heat of said stream of hot cracked products, passing said volatilized portions from the said distilling zone to said fractionating zone and therein condensing 'such crackable constituents, withdrawing such condensate substantially free from admixture with residual cracked products and unvolatilized feed stock and passing the said condensate directly to said cracking zone as charging stock therefor, collecting unvaporized residual products in said distilling zone in a body and maintaining said body of residual products at a cracking temperature of at least 700 F. by the heat of the said stream of cracked products discharged from said cracking zone into said distilling zone, and avoiding the passage of any of said residual products to said cracking passageway.

29. The improvement in the art of 'converting zone in a body and maintaining said body of hydrocarbon oils into gasoline-like products which comprises passing a charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products once-through an elongated heated pas- 8G) sageway and subjecting it to cracking during its passage therethrough for the production of gasoline-like products, discharging the stream of hot cracked products from said cracking zone into an externally unheated distilling zone, separating vapors in said distilling zone and passing them to a fractionating zone, continuously passing relatively cool feed stock in indirect heat exchange relation with vapors in said fractionating zone and thereafter discharging the preheated feed stock into direct contact with the said stream of hot cracked products entering the said distilling zone whereby crackable constituents are volatilized and said feed stock is raised to a cracking temperature solely by the heat of said stream of hot-cracked products, passing volatilized portions from the distilling zone to said fractionating zone and therein condensing such crackable constituents, withdrawing such condensate substantially free from admixture with residual cracked products and unvolatilized feed stock and passing it directly to the said cracking zone as charging stock therefor, collecting unvaporized residual products in said distilling residual products at a cracking temperature of at least 700 F. by the heat of the said stream of crackzd products discharged from said cracking zone into said distilling zone, and avoiding the passage of any of said residual products to the said cracking zone.

30. The improvement in the art of converting hydrocarbon oils into gasoline-like products which comprises passing a charging stock consisting substantially entirely of a normally liquid distillate oil heavier than the desired gasoline-like products once-through an elongated heated passageway and subjecting it to cracking during its passage therethrough for the production of gasoline-like products, discharging the stream of hot cracked products fromsaid cracking zone into an externally unheated distilling zone, separating vapors in said distilling zone and passing them to a fractionating'zone, continuously passing relatively cool feed stock in indirect heat exchange relation with vapors flowing from said distilling zone to said fractionating zone and thereafter discharging the preheated feed stock into direct contact with the said stream of hot cracked products entering the said distilling zone whereby crackable constituents are volatilized and said feed stock is raised to a cracking temperature solely by the heat of said stream of hot cracked products, passing said volatilized portions from the said distilling zone to said fractionating zone and therein condensing such crackable constituents, withdrawing such condensate substantially free from admixture with residual cracked prodiris *ucts and unvolatilized feed stock and passing it CERTIFICATE OF CORRECTION.

Patent No. 1,936,735. I November 28, 1933.

RENE de M. TAVEAU.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, line 82, claim 16, before "to" insert the word oil; and line 145-146, claim 20, for "frictionally" read fractionally; page 6, line 3, claim 21, for "converging" read converting; and line 128, claim 26, after "zone" strike out the comma; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 30th day of January, A. D. 1934.

F. M. Hopkins (Seal) Acting Commissioner of Patents.

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