US1939282A - Hydrocarbon oil conversion - Google Patents

Description

Dec. 12, 1933.

J. DELATTRE-SEGUY HYDROCARBON OIL CONVERSION Filed July 23, 1928 @Var/795g.

Patented Dec. l2, 1933 UNITED STATES HYDROCARBON OIL CONVERSION Jean Delattre-Seguy, Chicago, Ill., assgnor to Universal Oil Products Company, Chicago, Ill., a corporation of South Dakota Application July 23, 1928. Serial No. 294,746

7 Claims.

The invention relates to improvements in processes for converting heavy hydrocarbon oils into lighter hydrocarbon oils having the character of gasoline or the like suitable as motor fuels. and for other uses, and is more particularly directed to the production of a maximum quantity or yield of such lighter hydrocarbons, while at the same time producing residuum readily marketable, having a low viscosity and containing a minimum content of sludge or coke.

The invention is shown as applied to that type of process where the oil is passed through a heating tube under pressure, then into an enlarged drum which may" be under the same presure as the heating tube or under a lower pressure and where vapors separate from unvaporized oil, then the vapors are subjected tov reflux condensation and the reflux condensate as well asy the non-` vaporized oil from the drum are separately or together subjected to a so-called flashing-that is to say, they are passed together or separately into a common chamber or separate chambers where the pressure is released and where the lighter portions of the non-vaporized oil from the drum and of the reflux condensate separate, to be thereafter directed together through a vapor phase cracking tube for further treatment, while the portions of the non-vaporized oil and of the reflux which have not vaporized in the flash chambers are combined and withdrawn from the system in the form of marketable fuel.

The vapors leaving the vapor phase cracking tube may be subjected to dephlegmation and the reflux condensate may be returned to the first heating tube or elsewhere for retreatment.

In the operation of systems similar to that described, where the non-vaporized oil from the drum is ashed under reduced or released pressure and where, in general, a low or no level of non-vaporized oil is maintained in the drum, the coke formation in the drum is practically negligible, permitting long runs, and, in general, the residuum withdrawn from the flashing chamber contains a small amount of or no coke or sludge. However, it frequently happens, particularly when using heavy oils as charging stocks, that the residuum obtained in the manner above described from said oils is viscous and difliculty is experienced in marketing it and directing it through pipe lines to the various points of the fieldv or refinery. This is particularly marked when high yields of gasoline are secured from the operation.

With the advent of so-called anti-knock motor fuels, it has been the tendency of the cracking processes to subject selected fractions of charging stock to vapor phase cracking under atmospheric pressure or under a pressure slightly above atmospheric. For instance, the vapors produced by the flashing of the non-vaporized oil of pressure liquid and liquid-vapor cracking processes, and also reflux condensate from such processes after it has been vaporized, may be particularly selected for vapor phase cracking. These cuts form what may be called intermediate products of the cracking reaction.

One of the features of the present invention consists in'regulating, in a process of the character of those herein referred to, the .degree of evaporation of the reux condensate from the pressure zone of the cracking process in such a manner that a desired portion, to-wit: the heavier, remains unvaporized, and utilizing this portion as a solvent for the heavier portions of the non-vaporized oil, which-after flashingform the residuum from the process.

I have discovered that in this manner it is possible to substantially increase the yields of gasoline Without impairing the characteristics of the residuum produced from the process while at the same time securing a method of regulating the anti-knock properties of the gasoline-like motorfuel produced in the pressure liquid-vapor zone with those produced in the vapor phase cracking zone. The control of the anti-knock characteristics is obtained, among other ways, by the control of the degree of vaporization to which the reflux condensate and hon-vaporized oil from the pressure cracking zone are subjected.

Other features of the invention will appear from the following description and from the accompanying drawing, where the single gure is a diagrammatic sketchnot to scale-partly in elevation and partly in section of an apparatus which may be used to carry out the invention. 95

Referring to the drawing, raw oil may be charged from suitable sources of supply, not shown, through line 1 and pump 2 into feed line 3 and then into and through heating coil 4 positioned in a suitable furnace 5 heated by means of burners 6. In this coil the oil is heated to cracking temperature and then discharged through transfer line 7 provided with valve 8, into reaction chamber 9 which may be heavily insulated or mildly heated to maintain the oil therein at or near the cracking temperature that is received in the heating coil.

In reaction chamber 9, vapors are separated from the non-vaporized oil and withdrawn from the chamber through line 10 provided with valve 11, and passed into a dephlegmator 12 where, by means of a suitable cooling medium injected in the dephlegmator through line 13 provided with4 valve 14, said vapors are separated into suiliciently connected light products and insufliciently converted products. The former are withdrawn from the top of the dephlegmator through line'15 provided with valve 16, and thence passed through condenser 17 and line 18 into receiver 19 provided with gas release control 20 and distillate drawod' control 21.

The insudlciently converted products are condensed in the d ephlegmator 12 in the form of redux condensate and withdrawn therefrom through line 22` provided with pressure control valve 23 through which the redux condensate is discharged under a pressure lower than that maintained in dephlegmator 12, intoaso called flash chamber 24. The degree of vaporization of the redux condensate obtained in the `flash chamber 24 is primarily controlled by the difference in pressure between dephlegmator 12 and that of dash chamber 24; but I provide for an additional means to control the degree of vaporization of the redux condensate by providing heater 25 through which the redux condensate may be diverted on its way from dephlegmator 12 to flash chamber 24 by suitably controlling valve 23 online 22 and valves 26 on branch lines 27 and 28.

While I have shown the heater 25 as positioned in a separate furnace 29, it is obvious that the heater 25 may be positioned in the furnace 5 or in the furnacev of the vapor phase zone, which will be later described.

In the event that the redux condensate from dephlegmator 12 is reheated by being passed through heater 25, the pressure may be controlled by valve 26 either at the entrance of the heater 25 or at -the discharge thereof.

In the dash chamber 24, a controlled degree of vaporization is obtained as heretofore described, and the lighter portions of the redux condensate are withdrawn in the form of vapor through line 30 provided with valve 31, and directed to the vapor phase cracking zone, as will be later described.

'I'he heavier fractions of the redux condensate which have not vaporized in dash chamber 24 are withdrawn therefrom through line 32 and may be directed to storage through branch line 33 provided with valve 34, or they may be preferably directed through branch 35 provided with valve 36 into header 37 to be utilized as a thinning agent for the residuum as will be later explained Returning to the non-vaporized oil separated in the pressure reaction chamber 9, it may be withdrawn therefrom at such a rate that preferably no body of` oil is left to accumulate nor maintained in said chamber, thereby decreasing the formation of carbon by avoiding prolonged cracking. Non-vaporized oil may be withdrawn from the chamber through suitable drawoif lines 38 each provided with valve 39, and then passed into header 40 provided with pressure control valve 41, wherein said oil is introduced into dash chamber 42 under a pressure lower than that of the reaction chamber 9. The reduction of p'ressure obtained through valve 41 causes vaporization of a substantial portion of the residuum, and the degree of vaporization may be controlled by the degree of the reduction of pressure between the two chambers;

The vapors dashed in chamber 42 are withvalve 44, and may be combined with the vapors flashedfrom the redux condensate in chamber 24. rI-he combined. vapors are then directed through line 45 into vapor phase cracking coil 46 positioned in furnace 47v heated by suitable burners 48, where the vapors are subjected to with valve 53, into dephlegmator 54, and there the vapors are subjected to reflux condensation by means of suitable cooling agent injected into the dephlegmator through line 55 provided with valve 56. The non-condensed vapors are withdrawn from dephlegmator 54 through line 57 provided with valve 58', and thencev pass into condenser 59 and receiver 60, which latter may be provided with gas control 61 and distillate drawod control 62.

The vapors condensed in dephlegmator 54 in the form of redux condensate may be withdrawn therefrom through line 63 and may be directed to storage through branch line 64 provided with valve 65,. or through line 66, provided with valve 67, it may be directed to pump 68, whereby it is returned to the feed line 3 to the pressure heating coil 4.

The redux condensate from dephlegmator 54 may also be partly directed to the other portions of the plant and'particularly to the inlet of the reheating coil 25 or of thevapor cracking coil 46 by suitable connections, (not shown) and the possibility of dividing the redux condensate into various portions, each directed to a suitable point of the cracking process, provides for a very dexible cracking process.

.Returning now to the residuum separated in the dash chamber 42, it is withdrawn from the latter through line 69, provided with valve 70, and thence-into header 37 where it combines with non-vaporized portions of the redux withdrawn from dash chamber 24 through lines 32 and 35. In this manner the residuum produced by dashing 'the non-vaporized oil from the pressure cracking zone is thinned'down bythe heavier nonvaporized fraction of .the redux condensate from said zone, and this alsov serves in dissolving any tarry or asphaltic or sludge-like portions which may be carried by the residuum from the dash chamber 42. In this manner the viscosity of the residuum from the cracking process is reduced and a readily marketable product results from the cracking operation without decreasing the yield of gasoline obtainable therefrom.

vAs a further feature of the invention, the residuum separated in chamber 49 and withdrawn through line 50, may also be combined with the v residuum and heavy portions of the redux from dash chambers 42 and 24 respectively, and to this end line 50 is provided with branch line 71 provided with valve 72 whereby the residuum from drawn therefrom through line 43 provided with through the various parts of the process within the limitations above indicated in carrying out a process for the object thereof. Particularly the pressure may be equalized througout heating coil 4, chamber 9 and dephlegmator 12, condenser 17 and receiver 19, or differential pressures may be maintained between these various parts.

The ilash chambers 24 and 42 may be maintained at the same pressure or at different pressures, it being understood that the pressure on chamber 42' must be lower than the pressure on chamber 9, and the pressure on chamber 24 lower than the pressure on dephlegmator 12, and that the pressure at which the vapor phase cracking process is carried out in coil 46 may not be higher than the lowest pressure maintained in either chamber 42 or chamber 24.

The specific conditions exemplfying the process may be as follows:

A topped crude of 25 B. gravity is charged through line 1 by pump 2 into coil 4. The temperature at the outlet of coil 4 may be maintained at about 900 F. with a pressure of about 250 pounds maintained on both the coil 4 and chamber 9.

A pressure of about 50 to 100 pounds is maintained on the ash chamber 42. 'Ihe resulting residuum withdrawn has a gravity of approximately 5 B., and a viscosity of 400 Furol at 122 F.

'I'he temperature of coil 25 should be such that the temperature in chamber 24 is approximately 750 F. The pressure on the chamber 24 is maintained at about 50 pounds to 100 pounds.

Reflux residue is blended with the residue from chamber 42 in such a manner that the resulting mixture has a gravity of approximately '1 B. and a viscosity oi about 100 Furol at 122 F.

'I'he vapor phase coil is maintained at a temperature of about 1000" F. and under a pressure of about 100 pounds.'

I claim as my invention:

1. A process for cracking hydrocarbon oils which comprises subjecting oil to cracking conditions of pressure and temperature, separating the vapors and the non-vaporized oil, subjecting said vapors to reflux condensation, nally condensing the remaining vapors, withdrawing the reflux condensate and subjecting it to a vaporization under reduced pressure so controlled that the reflux condensate is not completely vapor-ized, subjecting the rst mentioned non-vaporized oil to partial vaporization under reduced pressure, removing the vapors obtained by said partial vaporization of said reilux condensate and of Vsaid non-vaporized oil, and mixing together the portions of said reflux condensate and of said non-vaporized oil which have not vaporized by said reduction of pressure, subjecting the vapors separated from the reflux condensate and from the non-vaporized oil by the reduction in pressure to vapor phase cracking by heat exchange with heating gases, separating the thus cracked yvapors into light sufficiently converted products and reux condensate, and subjecting said reux condensate to re-treatment with fresh charging stock in the primary cracking zone.

2. A hydrocarbon oil cracking process which comprises passing the oil in a restricted stream through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into a separating zone maintained under pressure and separating the same therein into vapors and unvaporized oil, removing the separated vapors and dephlegmating the same under pressure thereby forming reilux condensate, 'finally condensing the dephlegmated vapors as a product of the process, partially distilling such reflux condensate under lower pressure than is maintained in the dephlegmation step thereby forming a reflux residue, cracking the vapors evolved fromthe reflux condensate by heat exchange with heating gases and condensing the thus cracked vapors, separately removing unvaporized oil from the separating zone and ash distilling the same by pressure reduction independently of said reux condensate, recovering condensible hydrocarbons from the resultant ashed vapors, blending said reilux residue with the residuum of the flash distillation of the unvaporized oil and recovering the resultant blend as a product of the process.

3. A hydrocarbon oil cracking process which comprises passing the oil in a restricted stream through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into a separating zone maintained under pressure and separating the same therein into vapors and unvaporized oil, removing the separated vapors and dephlegmating the same under pressure thereby forming reux condensate, iinally condensing the dephlegmated vapors, partially distilling such re- Ilux condensate under lower pressure than is maintained in the dephlegmation step thereby forming a reiiux residue, separately removing unvaporized oil from the separating zone and ilash distilling the same by pressure reduction independently of said reflux condensate, blending said reiiux residue with the residuum of the flash distillation of the unvaporized oil and recovering the resultant blend as a product of the process, combining the vapors formed by the partial dlstillatlon of the reflux condensate with those evolved in the flashing of the unvaporized oil and subjecting the resultant vaporous mixture to vapor phase cracking by heat exchange with heating gases, and dephlegmating and condensing the vapor phase cracked vapors as another product of the process.

4. A process for cracking hydrocarbon oils which comprises subjecting the oil to cracking conditions of temperature and pressure, separating the vapors and the non-vaporized oil, subjecting said vapors to reilux condensation and then to ilnal condensation, subjecting the resultant reflux condensate to partial vaporization to produce vapors and residual reflux condensate, separately subjecting said non-vaporized oil to partial vaporization to produce vapors and a heavy residue, recovering condensible hydrocarbons from the last-named vapors, combining said residual reflux condensate with said residue and withdrawing the resultant mixture as a nal product of the process, vapor phase cracking the vapors evolved by the partial vaporization of the reflux condensate by heat exchange with heating gases, and dephlegmating and condensing the resultant vapor phase cracked vapors.

5. A process for cracking hydrocarbon oils which comprises subjecting the oil to cracking conditions of temperature and pressure, separating the vapors and the non-vaporized oil, subjecting said vapors to reflux condensation and then to nal condensation, subjecting the resultant reflux condensate to partial vaporization to produce vapors and residual reflux condensate, recovering condensible hydrocarbons from the last-named vapors,` separately subjecting said non-vaporized oil to partial vaporization to produce vapors and a heavy residue. combining said residual redux condensate with said residue and withdrawing the resultant mixture as a dnal product of the process, vapor phase cracking the vapors evolved by the partial vaporization of the non-vaporized oil by heat exchange with heating gases, and dephlegmating and condensing the resultant vapor phase cracked vapors.

6. -A process for cracking Vhydrocarbon oils which comprises subjecting the oil to cracking conditions of temperature and pressure, separating the vapors and the non-vaporized oil, subjecting said vapors to redux condensation and then to dnal condensation, subjecting the resultant comprises subjecting the oil to cracking conditions of temperature and pressure adequate to produce gasoline. separating the heated hydrocarbons into unvaporized oil and a vaporous mixture containing the gasoline and a substantial quantity of insumciently cracked fractions heavier than gasoline, condensing such insudicientiy cracked fractionsfrom said vaporous mixture while retaining the gasoline in vapor form, partially distilling the condensed insufficiently cracked fractions and thereby obtaining therefrom a redux residue, separately partially distilling said unvaporized oil and thereby reducing the same to a heavy residuum, combining said redux residue with said heavy residuum and collecting the resultant mixture as a product of the process, subjecting to vapor phase cracking the vapors evolved by the partial distillation of the condensed insufiiciently cracked fractions and of said unvaporized oil, by heat exchange with heating gases deplegmating the resultant vapor phase cracked vapors, and finally condensing the dephlegmated vapor phase cracked vapors and the gasoline vapors from which said insudiciently cracked fractions have been separated.

JEAN DELA'I'I'RE-SEGUY.

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