US2139672A - Combined liquid phase and vapor phase oil cracking process - Google Patents

Description

Deb. 13, 1938. B. P. CRITTENDEN 7 COMBINED LIQUID PHASE AND VAPOR PHASE OIL CRACKING PROCESS Filed Oct. 25, 1930 I k v i INVENTOR ATTORNEXS Patented Dec. 13, 1938 UNITED STATES PATENT OFFICE COMBINED LIQUID PHASE AND VAPOR PHASE OIL CRACKING PROCESS Application October 25, 1930, Serial No. 491,101

20 Claims.

This invention relates to a process by means of which petroleum oils, such as raw crude oil, reduced crude oil and gas oil, may be cracked to produce anti-detonating motor fuels, commercial gas oil and commercial fuel oil. It includes both liquid phase and vapor phase cracking. By this process, a specially selected charging stock, which is segregated during the operation, is subjected to liquid phase cracking and the cracked products therefrom are mixed with the raw stock andthe mixture introduced into a separator. A particular gas oil fraction segregated during the operation is subjected to vapor phase cracking and the products therefrom are introduced into the separator with the above-mentioned mixture. During the process, the incoming raw stock is preheated by passing it through heat exchangers that are heated by vapors and liquids from the cracking operations.

The invention will be understood from the description of the process which may be carried out by an arrangement of apparatus that is illustrated diagrammatically in the accompanying drawing.

In the accompanying drawing the single figure is a diagrammatic view showing an apparatus in which the improved process of the present invention may be carried out.

In the drawing; reference character I indicates a tank containing a supply of the oil to be cracked. A pump 2 forces the oil from the tank I through the pipe 3, heat exchangers 4, 5, E and 7 in series, and thence through the pipe 8 into another pipe l2, where it is mixed with the products from the liquid phase cracking coil 9 located in the furnace ID.

A vapor phase cracking coil I! is also located in the furnace H3. Pipes l2 and !3, that are provided with pressure release valves 14 and I5, respectively, lead from the coils 9 and H to a separator iii.

A pipe I! leads vapors from the upper portion of the separator #5 through the heat exchangers 6 and 5 in series in each of which a portion of the vapors is condensed. The remaining vapors pass through the pipe 18 and upwardly through the bubble tower E9, where more of the vapors are condensed. The remaining vapors then pass through the outlet pipe 2i! and heat exchanger 4 where more vapors are condensed. The final vapors pass from the heat exchanger 4 through a pipe 2| into a condenser (not shown).

Pipes 22 and 23 lead from the lower portions of the heat exchangers 5 and 5 to a pipe 24 that is provided with valves 25, 26 and 21 so located that they can be manipulated in such a manner that the condensates from the heat exchangers 5 and 6 can be introduced into the separator IE5 or an accumulator 28 located below the bubble tower l9, or all of the condensate from the heat exchanger 6 can be introduced into the separator I 6, while all of the condensate from the heat exchanger 5 can be introduced into the accumulator 28, or all of the condensates from the heat exchanger 6, together With a portion of that from the heat exchanger 5, can be introduced into the separator l6, while the remainder of the condensate from the heat exchanger 5 is introduced into the accumulator 2B, or all of the condensate from the heat exchanger 5, together with a portion of that from the heat exchanger 6, can be introduced into the accumulator 28, while the remainder of the condensate from the heat exchanger 6 is introduced into the separator IS.

A pump 29 is provided for forcing condensate from the accumulator 28 through the pipe 30 into the liquid phase cracking coil 9.

A pipe 3| leads from the lower portion of the bubble tower l9 into a stripping column 32, from which a pipe 33, provided with a valve 34, leads to a surge tank 35. A pump 35 is provided for forcing liquid from the surge tank 35 through the pipe 31 into the vapor phase cracking coil II. A pipe 38 provided with a valve 39 branches off from the pipe 33 and leads to a cooler 40, from which a pipe leads to a storage tank (not shown).

A pump M is provided for forcing liquid from p the lower portion of the separator it through the pipe 42, thence through the heat exchanger 1 and the pipe 43, and thence through the cooler 44 to a storage tank (not shown).

The operation is as follows: The raw oil, such as crude petroleum, reduced crude oil and gas oil, is forced by the pump 2 from the tank I through the heat exchangers 4, 5, 6 and 1 into the pipe l2, leading from the liquid phase cracking coil 9, between the pressure release valve I 4 and the separator I6. I have found that about lineal feet of contact in the pipe I! between the point of mixing and the separator l6 has given a very satisfactory control of the fuel gravity and control of fuel viscosity. The vapors in the separator l6 pass through the pipe l1, while the residue of the oil collects in the bottom of the separator IS. The vapors passing out through the pipe H are passed through the heat exchanger 5, where the relatively high boiling constituents condense and pass out through the pipe 23. The remainder of the vapors then passes int the heat exchanger 5., where somewhat lower boiling constituents condense and pass out through the pipe 22, the remaining vapors passing through the pipe l8 and into the bubble tower is. The condensates from the heat exchangers 5 and B that pass to the accumulator 28 are clean, low carbon residue products that are suitable as charging stock for the liquid phase cracking coil 9. The portions of the condensates from the heat exchangers 5 and 6 that are introduced into the separator 16 are used to regulate the gravity of the fuel oil that is desired to be produced and withdrawn from the bottom of this separator.

A fractionation and condensation of vapors leaving the heat exchanger 5 take place in the bubble tower l9, resulting in a separation and segregation of several fractions. The fraction that is not condensed in the bubble tower it passes through the heat exchanger 4 where more vapors condense, the condensate returning to the tower l9. Uncondensed vapors pass from the heat exchanger into a condenser through pipe 2|, where they are condensed and the condensate constitutes a commercial motor fuel. Another fraction is condensed in the bubble tower i9 and is withdrawn through the pipe 3! into the stripping column 32. A portion of it is used for the vapor phase cracking operation in coil Ii. The temperature in the cracking coil II should be about 1000 to 1100 F. Another fraction which has a higher boiling range than the fraction passing through the pipe 3|, passes into the accumulator 28 and is used, together with the condensates from the heat exchangers 5 and 6, as the charging stock for the liquid phase cracking coil &. The temperature in the cracking coil 9 should be about 875 to 950 F.

A portion of the condensate that passes through the stripping column 32 from the lower portion of the bubble tower I9 is withdrawn through the pipe 38 and constitutes the gas oil that is obtained from the process. The remainder of the gas oil from the stripping column 32 passes through the pipes 33 and 31 into the vapor phase cracking coil II.

By controlling the gas oil content of the vapors leaving the heat exchangers 5 and 6 and entering the bubble tower l9, as well as the temperature of the same, and simultaneously controlling the intermediate temperatures within the bubble tower [9 by spraying back over the top of the tower, such a fractionation is caused within the tower that the condensation of a high boiling range fraction results which is discharged into the accumulator 28 and a lighter gas oil fraction of desired boiling point range and carbon residue content is also separated and subsequently withdrawn through the pipe 3! into the stabilizing tower or stripping column 32.

The residue of oil that collects in the bottom of the separator "5, together with such portions of the condensates from heat exchangers 5 and 6 as are introduced into the separator, pass through the pipe 42, heat exchanger 1 and pipe 33 and cooler 44 and constitute the fuel oil that is obtained from the process.

By this invention, commercial petroleum fractions can be separated from crude petroleum. The crude petroleum or other oil that is to be treated is preheated by liquids or vapors that have received heat in the cracking coils. The temperature of the mixture of preheated raw material and efilux from the cracking coil '8 which passes into the separator Hi, can be controlled so that the mixture separates in the separator into a vaporized portion that passes out through the pipe I! and a fuel oil fraction of the desired gravity that passes out through the pipe M is obtained having a low total fixed carbon content and low viscosity even when raw material of different characteristics are preheated and charged into eiliux pipe l2. However, for the production of fuel oil of these characteristics it is desirable to have a raw material that contains a fraction having a specific gravity approximately equal to that of the fuel oil that it is desired to produce. If the material being treated does not contain such a fraction but contains a fraction of higher gravity, a fuel oil of desired characteristics may still be obtained but will require an increase in time of contact between the raw material entering through the pipe 8 and the material passing out of the release valve M in the pipe l2. The time of contact may be varied by changing the point at which the pipe 8 enters the pipe I2; Of course, the superheat in the vapors passing out of the pressure release valve I4 is available for aiding in completing the final vaporization of the mixture from the heating coil 9 and pipe 8.

The heavy gas oil which accumulates in the accumulator 28 as described above and is cracked in the cracking coil 9, is free from low boiling fractions and is of a moderately heavy gravity. It contains a very small amount of fixed carbon or carbon residues and is relatively free from harmful chemical constituents which would give trouble in the cracking coil by producing excessive wear or destruction of the cracking coil 1 or accessory apparatus and would also carry into the motor fuel that is produced from the process chemical constituents which would require costly chemical treatment to remove the same, resulting in loss of material and large expense. The fraction from the accumulator 28 is very much more suitable for being cracked in the coil 9 to produce motor fuels, gas oils and fuel oils than would be true of a charging stock that contains large quantities of light fractions and large quantities of fixed carbon or carbon residues. This fraction used for charging the cracking. coil 9 permits the use of greatly elevated temperatures in this coil without requiring increased pressures and the result is the production of motor fuel of greatly increased anti-detonating qualities.

By using the condensate that passes out of the bubble tower through the pipe 3! as the charging stock for the cracking coil ll, very desirable results are obtained in the production of motor fuels, gas oils and fuel oils in accordance with this invention. Although even if the motor fuel fraction of the materialpassing out through the pipe l3 into the separator '56 contains constituents that would be harmful to the operation of internal combustion engines unless special chemical treatment is given thereto, it has been found that by introducing the efilux from the cracking coil H into the separator l6 as described above, the materials become mixed and chemical reactions appear to take place, with the result that the motor fuel that is obtained from the vapors leaving the separator I6 through the pipe I! possesses exceptionally high antidetonating value and is free from the harmful constituents that were present in the efflux from the cracking coil H. In this way, the expensive chemical treatment is avoided and the volumetric losses in such treatment does not occur.

The harmful constituents appear to remain in the residual oil at the bottom of the separator and pass out in the fuel oil and do not, therefore, remain in the vaporized portions of the efiiux from the cracking coils 9 and H to deposit in the pipes and obstruct the same.

I claim:

1. The process of cracking petroleum oils for the formation of a high anti-knock gasoline, which comprises subjecting the vapors from a cracking operation to a fractional condensing operation in which a relatively heavy product and a relatively light product of higher boiling point than the desired gasoline are obtained, heating the relatively heavy product in a confined stream to a cracking temperature of from 875 to 950 F. and passing the resulting highly heated products through a relatively long transfer line into a separating zone, separating vapors from unvaporized oil constituents in said separating zone, preheating a charging stock for the process and introducing the same into the hot oil products in the said transfer line at a point about 130 feet along said line from said separating zone whereby the mingled products in said transfer line are thoroughly mixed and their temperatures substantially equalized prior to being discharged into said separating zone, heating said relatively light product to a high cracking temperature of from 1000 to 1100 F. while conducting the same in a confined stream through a heating zone, passing the resulting highly heated oil constituents from the heating of said light oil product into said separating zone, wherein they are mingled with the products discharged from said transfer line, subjecting the vapors separated in said separating zone to said fractional condensing operation and condensing a high anti-knock motor fuel product from Vapors uncondensed in said fractionating operation.

2. The process of cracking petroleum oils for the production of a high anti-knock gasoline motor fuel, which comprises producing a relatively heavy and a relatively light reflux condensate in the cracking operation, cracking the relatively heavy condensate by heating it to a high temperature while passing it in a confined stream through a heating zone, conducting the resulting products through a transfer line into a separating zone in which vapors are separated from unvaporized oil constituents, introducing charge oil stock for the process into the stream of the highly heated products at a point a substantial distance along the transfer line from said separating zone whereby sufficient time is allowed for the thorough mingling of the charge oil and highly heated products prior to their introduction into said separating zone, heating the relatively light reflux condensate in a separate confined stream to a temperature sufficient to effect cracking thereof in vapor phase, said temperature being substantially higher than the temperature to which the heavy reflux condensate was subjected, and introducing the products resulting from the heating of the relatively light reflux condensate into said separating zone in intimate contact with the vapors of said heavy reflux condensate and charging stock to thereby aid in producing a substantially stable gasoline product.

3. The process of cracking petroleum oils for the formation of a high anti-knock motor fuel, which comprises producing a relatively high boiling point gas oil fraction and a relatively low boiling point gas oil fraction from the vapors produced in the cracking process, said gas oil fractions being relatively low in carbon residue content, separately cracking the said fractions by heating each fraction to a temperature particularly adapted to its conversion in substantial proportion to lower boiling point products, said heating including the heating of the relatively low boiling point gas oil fraction to a substantially higher temperature than that to which the relatively high boiling point gas oil fraction is heated, preheating fresh charging stock for the cracking precess by passing it in indirect heat exchange with vapors produced in the cracking operation and intimately mixing it with the high-- ly heated high boiling point gas oil fraction, maintaining the resulting mixed oils in intimate contact for a substantial period of time and then passing the same into a vapor-liquid separating zone, introducing the highly heated products resulting from cracking said low boiling point fraction into the vapors in said separating zone, and subjecting the vapors separated in said separating zone to fractional condensing conditions to produce said gas oil fractions and said anti-knock motor fuel.

4. The process of cracking petroleum oils for the production of a high antiknock gasoline motor fuel and a marketable fuel oil, which comprises cracking a relatively heavy distillate by heating it to a high cracking temperature while passing in a confined stream through a heating zone,

conducting the resulting products through a relatively long transfer line' into a separating zone in a large chamber in the lower portion of which vapors are separated from unvaporized oil constituents, introducing a preheated relatively heavy residue containing fresh charging stock for the process into the stream of said highly heated products at a point a substantial distance along the transfer line from said separating zone whereby suflicient time is allowed for thorough mingling of the charge oil and the highly heated products prior to their introduction into said separating zone and whereby said fresh charging stock is heated sufficiently to produce a fuel oil residue of low viscosity, withdrawing a marketable fuel oil from the lower portion of the separating zone and removing it from the system, and subjecting the vapors separated in the separating zone to fractional condensing conditions to separate out a high antiknock gasoline product.

5. The process defined by claim 4 in which a plurality of reflux condensates of higher boiling point than gasoline are produced in the vapor fractionating operation, and introducing into the separating zone a regulated portion of the higher boiling point reflux condensate to aid in controlling the quality of the fuel oil Withdrawn from the separating zone.

6. The process of cracking mineral oils which comprises, passing an oil distillate in a confined stream of restricted cross section through a heating zone and therein heating and cracking the said distillate, passing the highly heated and cracked distillate products through a transfer line directly into the lower portion of an enlarged unobstructed vertical vapor liquid separating zone in a large vertical chamber, substantially reducing the pressure on said highly heated distillate products in said transfer line and introducing directly thereinto a stream of relatively heavy preheated fresh oil charging stock at a point subsequent to said pressure reduction and at a substantial distance along said transfer line from said separating zone, whereby the length of contact between said highly heated distillate products and said heavy fresh oil charging stock in said transfer line is sufficient to reduce the viscosity of said stock and produce a marketable fuel oil having a predetermined viscosity, separating the unvaporized fuel oil constituents from the vapors in the lower portion of said separating zone, discharging the separated fuel oil constituents from the bottom of the separating zone and removing them from the system, removing the separated vapors from the upper portion of said separating zone, fractionating the vapors removed from said separating zone into a plurality of relatively high boiling point condensate fractions, and selecting condensate having a relatively low carbon residue content from said fractions to supply at least in part 'said distillate oil for said heating zone.

'7. A hydrocarbon oil cracking process which comprises passing a relatively heavy oil through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into the lower portion of a substantially vertical reaction zone in a large vertical chamber maintained under cracking conditions of temperature and pressure, separating the heated oil into vapors and unvaporized oil in the lower portion of the reaction zone and withdrawing the separated unvaporized oil from the lower portion of said reaction zone and removing it from the system, simultaneously heating a lighter oil in a second cracking zone to a higher cracking temperature than that to which said relatively heavy oil was heated and then discharging the resulting products into said reaction zone a substantial distance below the top thereof and above the point of introduction of said heated oil, thereby preventing contact between the vapors of the lighter oil products and said unvaporized oil, and commingling the lighter oil vapors with the first-mentioned vapors, passing the commingled vapors upwardly through said reaction zone and removing the same from the upper portion thereof, and fractionating and condensing the vapors withdrawn from the reaction zone.

8. The process of converting hydrocarbon oils into anti-detonating motor fuel products, which comprises passing a relatively high boiling point oil in a confined stream of restricted cross section through a heating zone and subjecting the stream of oil therein to a temperature and pressure sufficient to effect conversion thereof, conducting the resulting highly heated products from said zone into the lower portion of an enlarged vertical separating zone in a large vertical chamber in the lower portion of which vapors are separated from unvaporized oil constituents, the latter of which are collected in the bottom of the separating zone, withdrawn therefrom and removed from the system, heating and cracking a relatively lighter oil stock in a second cracking zone through which the oil stock is passed in a confined stream of restricted cross section, heat ing the said lighter stock to a higher cracking temperature than that to which said relatively heavy stock is subjected and then introducing the products from the second cracking zone into said enlarged separating zone at a point substantially below the top thereof but above the point of introduction of the hot oil products from the first-mentioned cracking zone, whereby the vapors of said relatively lighter oil are brought in contact with the separated vapors of the relatively heavy oil in said separating zone, passing the resulting mixed vapors upwardly through said separating zone in an unobstructed path and removing the same from the upper portion thereof, and fractionally condensing the vapors withdrawn from the separating zone.

9. In the art of processing crude petroleum oil for the production of valuable products therefrom, the improvement which comprises passing the crude petroleum oil charging stock to be processed through a primary condensing zone in indirect heat exchange with high temperature cracked vapors and vapors resulting from the distillation of the crude oil to heat the crude oil and produce fractional condensation of the said vapors, passing the remaining vapors from said primary condensing zone into a secondary fractionating zone to effect further condensation of relatively high boiling point constituents contained in the vapors, introducing the heated crude petroleum oil into an enlarged vapor separating zone in a large chamber in which substantial portions of the oil is vaporized, conducting the resulting vapors to said primary condensing zone, passing relatively high boiling point condensate from one of said condensing zones in a confined stream of restricted cross section and subjecting it to'cracking conditions at a relatively high temperature, introducing the resulting highly heated products from said cracking zone into intimate contact with the heated crude oil introduced into said enlarged separating zone, withdrawing unvaporized oil constituents separated out in said separating zone from the lower portion thereof to comprise a fuel oil product of predetermined viscosity which is removed directly from the system, and withdrawing a high anti-knock motor fuel vapor product from said secondary fractionating zone.

10. The process defined by claim 9 in which at least a portion of the condensate formed in said primary condensing zone is introduced directly into said enlarged separating zoneto aid in controlling the gravity of the fuel oil collected in the lower portion thereof.

11. In the art of converting hydrocarbon oils for the production of high anti-knock motor fuel products, the process which comprises passing a relatively light charging stock in a confined stream of restricted cross section through a heating zone and heating the oil of said stream to a high cracking temperature of the order of 1000 F., preheating a crude petroleum oil charging stock containing heavy residual constituents, introducing the cracked products from said cracking zone and the said preheated charging stock into one end portion of an enlarged separating chamber in which vapors are separated from unvaporized oil constituents which are collected in the bottom of the chamber, withdrawn therefrom and removed from the system, withdrawing the vapor mixture separated out in said separating zone and subjecting the same to fractional condensing conditions to produce a plurality of fractional condensates of higher boiling point than the desired gasoline product, condensing the separated gasoline vapors resulting from said fractionation, separately cracking a relatively heavy reflux condensate produced in said fractionating operation at a temperature slightly lower than that employed in the cracking of said light oil to produce additional quantities of high anti-knock motor fuel, and introducing the .resulting cracked products into said end portion of said chamber in intimate contact with the other oil products introduced thereinto.

12. The process of cracking petroleum oils for (ill the formation of a high antiknock gasoline and the production of a marketable fuel oil, which comprises heating a relatively heavy distillate oil cracking stock in a confined stream to a cracking temperature of from 875 to 950 F. and passing the resulting highly heated products through a relatively long transfer line directly into the lower portion of a separating zone in a large chamber, separating vapors from unvaporized oil constituents in the lower portion of said separating zone, preheating a relatively heavy residue containing fresh charging stock for the process and introducing the same directly into the hot oil products in said transfer line at a point about 130 feet along said line from said separating zone whereby the mingled products in said transfer line are thoroughly mixed and their temperatures substantially equalized prior to being discharged into said separating zone and the residue in said stock heated to a temperature adapted to produce a low viscosity fuel oil, withdrawing a marketable fuel oil of low viscosity from the bottom of said separating zone and removing it from the system, passing the vapors separated in said separating zone from the upper portion thereof and subjecting them to a fractional condensing operation, and condensing a high antiknock motor fuel product from vapors uncondensed in said fractionating operation.

13. A hydrocarbon oil cracking process which comprises passing a relatively heavy reflux distillate produced in the cracking operation through a heating zone and heating the same therein to a cracking temperature under pressure, discharging the heated oil into the lower portion of a substantially vertical reaction zone in an enlarged vertical chamber maintained under cracking conditions of temperature and pressure, separating the heated oil into vapors and unvaporized oil in the lower portion of the reaction zone in said chamber, collecting separated unvaporized oil in the bottom of said chamber and withdrawing it therefrom, simultaneously heating a lighter reflux distillate produced in the cracking operation in a second cracking zone to a higher cracking temperature than that to which said relatively heavy distillate was heated and then discharging the resulting highly heated products into said reaction zone a substantial distance below the top thereof and at a point above the introduction of said heated oil, commingling the highly heated products introduced into said zone with the firstmentioned vapors, passing the resulting commingled vapors upwardly through the reaction zone and removing the same from the upper portion thereof, and fractionating the vapors removed from the upper portion of said reaction zone to produce said reflux distillates and a final gasoline product.

14. A hydrocarbon oil cracking process which comprises passing a relatively heavy oil through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into the lower portion of a substantially vertical reaction zone in a large vertical chamber maintained under cracking conditions of temperature and pressure, separating the heated oil into vapors and unvaporized oil in the lower portion of the reaction zone and withdrawing the unvaporized oil therefrom as it collects in the bottom of the reaction zone, simultaneously heating a lighter oil in a second cracking zone to higher cracking temperature than said heavy oil and then discharging the same into the reaction zone a substantial distance below the top thereof and above the point of introduction of said heated oil, thereby preventing contact between the vapors of the lighter oil and said unvaporized oil and commingling the lighter oil vapors with the first-mentioned vapors, passingthe comingled vapors upwardly through the reaction zone and removing the same from the upper portion thereof, and fractionating and condensing the withdrawn vapors.

15. A hydrocarbon oil cracking process which comprises passing a relatively heavy reflux distillate produced in the cracking operation through a heating zone and heating the same therein to a cracking temperature under pressure, discharging the heated oil into the lower portion of a substantially vertical reaction chamber maintained under cracking conditions of temperature and pressure, separating the heated oil into vapors and unvaporized oil in the lower portion of the reaction chamber, collecting the unvaporized oil in the bottom of the chamber and withdrawing the same from the bottom of the chamber and removing it from the system, simultaneously heating a lighter reflux distillate produced in the cracking operation in a second cracking zone to a higher cracking temperature than that to which said relatively heavy distillate washeated and then discharging the resulting highly heated products into said reaction chamber a substantial distance belowthe top thereof and at a point above the introduction of said heated oil, commingling the highly heated products introduced into said chamber with the first-mentioned vapors, passing the resulting commingled vapors upwardly through the reaction chamber and removing the same from the upper portion thereof, fractionating the vapors removed from the upper portion of said reaction chamber to produce a heavy condensate of relatively high carbon residue content as well as said reflux distillates and a final gasoline product, and introducing said heavy condensate directly into said reaction zone.

16. A hydrocarbon oil cracking process which comprises passing a relatively heavy oil through a heating zone and heating the same therein to cracking temperature under pressure, discharg ing the heated oil into the lower portion of a substantially vertical reaction zone in a large vertical chamber maintained under cracking conditions of temperature and pressure, separating the heated oil into vapors and unvaporized oil in the lower portion of the reaction zone and withdrawing the separated unvaporized oil from the lower portion of said reaction zone and removing it from the system, simultaneously heating a lighter oil in a second cracking zone to a higher cracking temperature than that to which said relatively heavy oil was heated and then discharging the resulting products into said reaction zone a substantial distance below the top thereof and above the point of introduction of said heated oil, thereby preventing contact between the vapors of the lighter oil products and said unvaporized oil, and commingling the lighter oil vapors with the first-mentioned vapors, passing the commingled vapors upwardly through said reaction zone and removing the same from the upper portion thereof, passing the vapors removed from the upper portion of the reaction zone in heat exchange with a residue-containing fresh oil charging stock and introducing the resulting preheated charging stock directly into the heated heavy oil introduced into said reaction zone, and fractionating and condensing the vapors following said heat exchange with said stock.

17. The process of cracking hydrocarbon oils, which comprises passing a distillate oil through a heating and cracking zone and heating the same therein to a cracking temperature to cause formation of high antiknock constituents, passing the resulting cracked products into an enlarged reaction zone in a large chamber maintained at a cracking temperature under superatmospheric pressure wherein cracking is continued and separation of vapors from liquid occurs, passing the separated vapors from said reaction zone into a heat exchange zone wherein separation of vapors and liquid high boiling condensate occurs, passing the separated vapors from said heat exchange zone to a fractionating tower in which the vapors are separated by fractionation to produce a reflux distillate, conducting said distillate to said heating and cracking zone, passing fresh oil charging stock containing residual constituents into said heat exchange zone and therein preheating said stock and condensing high-er boiling constituents of said vapors, passing said preheated stock from said heat exchange zone and combining it with highly heated products discharged from said heating zone whereby the resulting combined products are brought in intimate contact and their temperatures substantially equalized in said en larged reaction zone thereby to reduce the viscosity of the residual products in said stock, col lecting the separated residual products in the bottom of said enlarged reaction zone and withdrawing the same from the bottom of said reaction zone as a finished heavy fuel oil.

18. The process of cracking petroleum oils for the formation of a high antiknock gasoline and the production of a marketable fuel oil which comprises passing a distillate oil in a confined stream of restricted cross section through a heating zone and heating and cracking the oil therein under conditions adapted to produce high antiknock gasoline products, conducting the resulting highly heated cracked products from said heating zone into an enlarged reaction zone in a large chamber in which vapors are separated from unvaporized oil constituents and the vapors maintained under cracking conditions in said enlarged zone, passing the high temperature cracked vapors from said reaction zone into a preliminary refluxing zone in heat exchange with preheated charging stock containing residual constituents of undesired viscosity for fuel oil purposes, effecting condensation of some of the heavy constituents of said vapors particularly the coke-forming constituents and returning such condensate directly to said enlarged reaction zone, passing the preheated charging stock into intimate contact with the highly heated products from said heating zone to break the viscosity of the residual constituents in said stock, maintaining said stock in contact with said highly heated constituents for a sufficient time to effect the desired conversion of the residual constituents into products of suitably low viscosity for fuel oil purposes, collecting the unvaporized oil constituents including the unvaporized portion of said stock in the bottom of said enlarged reaction zone and withdrawing the same therefrom as a finished fuel oil, passing the uncondensed vapors from said preliminary fractionating zone into a further fractionating zone in which a reflux distillate is recovered, and passing said distillate to said heating zone.

19. The process of cracking petroleum oils for the formation of a high antiknock motor fuel which comprises producing a relatively high boil ing point gas oil fraction and a relatively low boiling point gas oil fraction from the vapors produced in the cracking process, said gas oil fractions being relatively low in carbon residue content, separately cracking said fractions by heating each fraction to a temperature particularly adapted for its conversion in substantial proportion to lower boiling point products, said heating including the heating of the relatively low boiling point gas oil fraction to a substantially higher temperature than that to which the relatively high boiling point gas oil fraction is heated, introducing the resulting highly heated products into an enlarged reaction zone in a large chamber in which unvaporized oil constituents separate and collect in the bottom of the zone, heating a fresh charging stock containing residual constituents to a temperature adapted to break the viscosity of the residual constituents and maintaining it at such temperature for a sumcient time to complete the desired viscosity breaking operation, introducing said heated charging stock into said enlarged reaction zone and collecting unvaporized constituents thereof in the bottom of said zone, withdrawing the unvaporized oil constituents from the bottom of said reaction zone as a finished fuel oil product, and subjecting the vapors separated in said enlarged reaction zone to fractional condensation to produce said gas oil fractions and said antiknock motor fuel.

20. The process defined by claim 19 in which the vapors removed from said enlarged reaction zone are subjected to a preliminary refluxing operation to condense out the heavy coke and carbon-forming constituents and introducing the resulting heavy reflux condensate into said enlarged reaction zone without passing the same through either of said heating zones.

BUTLER P. CRITTENDEN.

Images