US2126989A - Conversion of hydrocarbon oils - Google Patents

Description

Aug. 16, 1938. A. ENGELSTEIN CONVERSION OF HYDROCARBON O II.

Filed March 26. 1936 mv swim. wz u INVENTOR ALVIN ENGELSTEI N ATTORNEY Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Application March 26, 1936, Serial No. 70,910

16 Claims.

This invention particularly refers to an improved process for the fractional distillation of hydrocarbon oils of relatively wide boiling range such as crude petroleum, topped crude and the like, accompanied by the pyrolytlc conversion of selected fractions of the charging stock and selected intermediate conversion products of the process under independently controlled cracking conditions, wherein heated products resulting m from the selective conversion of intermediate liquid products of the process are commingled with the charging stock in the fractional distilling zone to effect or assist its fractional distillation and wherein selected low-boiling fractions of the charging stock or low-boiling fractions of the intermediate liquid conversion products, or both, after being heated to a high cracking temperature may be utilized, when desired, to assist coking of the residual liquid conversion products and high-boiling fractions of the charging stock.

In the preferred embodiment of the invention, charging stock for the process, comprising an oil of relatively wide boiling range, is supplied, with or without prior heating, to a fractional distilling zone wherein it is subjected to appreciable vaporization and fractionation together with conversion products from a cracking coil of the system to which intermediate liquid conversion products of the process are supplied as will be later described.

Selected intermediate fractions of the charging stock and the conversion products supplied to the fractional distilling zone are withdrawn therefrom as liquid condensate,-subjected to controlled conversion conditions of cracking temperature and superatmospheric pressure in a heating coil and introduced into a vaporizing and separating chamber wherein the vaporous and residual liquid components of the conversion products are separated and wherefrom the vaporous products are supplied to a separate fractionating zone, fractionated vapors of the desired end-boiling point from the last mentioned fractionating zone are subjected to condensation and the resulting distillate, preferably comprising materials within the boiling range of motor fuel and of good antiknock value, is recovered. The total reflux condensate formed in the last mentioned fractionating zone may be removed therefrom in commingled state or may be separated into selected relatively low-boiling and high-boiling fractions and the total reflux condensate or only its highboiling fractions, as desired, are subjected to independently controlled conversion conditions of cracking temperature and superatmospheric pressure in a separate heating coil from which the resulting heated products are supplied, as previously mentioned, to the fractional distilling column to which the charging stock is supplied. Low-boiling fractions of the commingled charging stock and vaporous conversion products are removed as the overhead vaporous product from the fractional distilling zone, subjected to condensation and the resulting distillate collected. When this distillate is a material of satisfactory motor fuel characteristics it may be recovered as one of the final light distillate products of the process. When, on the other hand, it comprises materials within the boiling range of motor fuel which are of unsatisfactory antiknock value it may be subjected in another separate heating coil to reforming conditions of cracking temperature and substantial superatmospheric pressure and the resulting heated products introduced into a separate vaporizing and separating chamber which may, when desired, be operated as a coking zone. High-boiling non-vaporous components of the charging stock and residual liquid components of the conversion products supplied to the fractional distilling zone are removed therefrom and may either be supplied directly to said separate vaporizing and separating zone or first passed through a separate heating coil wherein they may be either heated sufiiciently to induce their subsequent reduction to coke in said separate vaporizing or separating chamber or may be subjected to viscosity breaking conditions of relatively mild cracking temperature and superatmospheric pressure. Vaporous products from the separate vaporizing and separating or coking chamber are supplied to the first mentioned vaporizing and separating chamber and residual liquid conversion products withdrawn from the latter zone may either be recovered, all or in part, as a final product of the process or supplied to saidseparate vaporizing and separating or coking chamber for further treatment. When the reflux condensate formed in the second mentioned fractionating step is separated into selected relatively low-boiling and high-boiling fractions said low-boiling fractions are preferably passed through a separate heating coil wherein they are subjected to relatively severe conversion conditions of cracking temperature and superatmospheric pressure from which the resulting heated products are supplied to said separate vaporizing and separating or coking chamber and, when the overhead distillate product from the fractional distilling step is subjected to reforming, the same heating coil employed for this service may also be utilized for said cracking of 55 the low-boiling fractions of the reflux condensate from the second fractionating step.

A feature of the invention resides in the wide flexibility of operation which it provides, to permit the optimum treatment of charging stocks of different characteristics and to permit the production of a wide range-of products which may be varied to suit economic conditions as well as the particular characteristics of the charging stock.

The invention is, of course, not limited to the use of all of the various steps above outlined in combination since alternative but non-equivalent methods of operation are provided and some of the steps may be modified or omitted without departing from the scope of the invention.

The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the features of the invention and providing means for accomplishing the various steps and alternative methods of operation above outlined.

Referring to the drawing, the oil supplied to heating coil I, in the manner to be later described, which comprises intermediate fractions of the charging stock and intermediate liquid conversion products of the process, is subjected during its passage therethrough to the desired cracking temperature, preferably at a substantial superatmospheric pressure by means of heat supplied thereto from a furnace 2. The heated conversion products are discharged from heating coil i through line 3 and valve 4 into chamber Chamber 5 is a zone wherein separation of the vaporous and residual liquid components of the conversion products supplied thereto is accomplished and this chamber may either be operated at a substantial superatmospheric pressure, in order to subject the conversion products to continued cracking in this zone, or it may be operated at a substantially reduced pressure relative to that employed in heating coil I in order to retard or arrest the cracking operation and induce appreciable further vaporization in this zone chamber 5 is removed from the lower portion of this zone through line i and may be directed, all or in part, through line I and valve 4 to cooling and storage or elsewhere, as desired, or it may be supplied, all or in part, through valve 9 in line 6 to pump II and directed therefrom through line H and valve I 2 into chamber l3, wherein it may be subjected either to further vaporization for the production of higher boiling liquid residue or wherein it may be reduced to coke.

Vaporous conversion products are removed from the upper portion of chamber 3 and directed through line l4 and valve l5 to fractionation in fractionato'r I, wherein their components boiling above the range of the desired final light distillate product of this stage of the process are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling point are withdrawn, together with gaseous products of the cracking operation, from. the upper portion of fractionator Ii and are directed through line I! and valve II to condensation and any desired further treatment. This product preferably comprises materials within the boiling range of motor fuel and of good antiknock value. When desired, regulated quantities of the distillate collected in receiver 22 may be recirculated by well known means, not illustrated in the drawing, to the upper portion of 'fractionator I to serve as a refluxing and cooling medium in this zone for assisting fractionation of the vapors and to maintain the desired vapor outlet tem 'perature therefrom.

The total reflux condensate formed in fractionator It may, when desired, be withdrawn from the lower portion of this zone through line 21 and valve 23 to pump 29 by means of which it is supplied through line 30 and valve 3| to cracking in heating coil 32. As an alternative to this method of operation, the reflux, condensate formed in fractionator I! may be separated, when desired, into selected relatively low-boiling and high-boiling fractions. In the latter case, only the high-boiling fractions of the reflux condensate are supplied from the lower portion of fractionator It, in the manner described, to heating coil 32 while the selected lower boiling fractions are separately removed from one or a plurality of suitable intermediate points in the fractionator; provision being made in the case here illustrated for directing the low-boiling reflux condensate through line 36 and valve 3'! to pump 38 by means of which it is directed through line 3! and valve 40 to cracking in heating coil 4|.

The total or high-boiling fractions of the reflux condensate from fractionator l6 supplied, as described, to heating coil 32 are subjected in this zone to the desired cracking temperature, preferably at a substantial superatmospheric pressure, and the resulting heated products are directed through line 34 and valve into distilling and fractionating column 45 wherein their Vaporous and residual liquid components separate and the former are subjected to fractionation.

Charging stock for the process which, as previously mentioned, preferably comprises an oil of relatively wide boiling range, is supplied through line 46 and valve 41 to pump 48 by means of which it is introduced through line 49 and valve 50 into distilling and fractionating column 45. When desired, the charging stock may, of course, be preheated in any suitable manner, not illustrated in the drawing, prior to its introduction into column 45 but in most cases the heat supplied to the charging stock in column 45, by its contact in this zone with the hot conversion products from heating coil 32, will be suflicient to vaporize the charging stock to the desired degree and effect fractionation of its Vaporous components, together with the commingled vaporous conversion products.

'li'he charging stock and conversion products supplied, as described, to column 45 are separated by vaporization and fractionation in this zone into selective relatively low-boiling, intermediate and high-boiling fractions. The relatively lowboiling'fractions preferably comprise materials within the boiling range of motor fuel and may also include, when desired, somewhat higher boiling materials such as naphtha, kerosene and the like and this fraction is withdrawn as fraction ated vapors from the upper portion of column 45 and directed through line SI and valve 52 to condensation and cooling in condenser 53. The resulting distillate and uncondensed gases pass through line 54 and valve 55 to collection and separation in receiver 58. Uncondensed gases may be released from the receiver through line 51 and valve 54 and all or a portion of the distillate collected in receiver 56 may, when desired, be removed therefrom as a final product of the process through line 58 and valve 59 to storage or to any desired further treatment.

The intermediate fractions of the commingled materials in column 45, which preferably comprise the high-boiling components of the vaporous portions of the conversion products and charging stock, including principally such materials as gas oil and also including, when desired, somewhat lower boiling oils such as kerosene or kerosene distillate, are removed from one or a plurality of suitable intermediate points in column 45 and directed through line 60 and valve 6| to pump 52 by means of which they are supplied through line 53 and valve 64 to conversion in heating coil I, in the manner previously described.

The high-boiling components of the commingled charging stock and conversion products in column 45, preferably comprising oils of a relatively high-boiling residual nature, are removed from the lower portion of the column through line 65 and valve 66 to pump 61 by means of which they are fed through line 68 and may be supplied either direct through valve 69 in this line to chamber |3 or, when desired, it may be diverted from line 68 through line 10 and valve 1| to heating coil 12 the function of which will be later described, and thence directed through line 14, valve 15 and lines 43 and 68 into chamber l3.

In case the overhead distillate product from column 45, which is collected in receiver 55, comprises motor fuel and/or naphtha which is not of satisfactory motor fuel characteristics, particularly with respect to its antiknock value, a portion or all of this material may be diverted from line 58 through line 16 and valve to pump 18 by means of which it is supplied through line l9 and valve 8|] to reforming in heating coil 4|.

The relatively low-boiling oils supplied to heating coil 4| which, as is apparent from the foregoing description, may comprise either distillate from receiver 56 or low-boiling fractions of the reflux condensate formed in fractionator H5, or both, are subjected during their passage through the heating coil preferably to a relatively high cracking temperature at substantial superatmospheric pressure by means of heat supplied from furnace 42. The highly heated products are directed from heating coil 4| through line 43 and valve 44 and are thence directed through line 68 into chamber |3, preferably after commingling either in line 68 or in line 43 with the residual liquids supplied to chamber l3 from column 45, as previously described.

In case the heated products from heating coil 4| commingle in line 68 with the higher boiling oils from column 45 without previously heating the latter in heating coil 12 to a high conversion temperature, the heavy liquids serve to partially cool the stream of hot conversion products from heating coil 4| and by this heat exchange are thereby heated to a relatively mild conversion temperature. By this method of operation substantial additional conversion of the highly heated products from heating coil 4| may be prevented but by employing a substantial superatmospheric pressure in chamber l3 the residual liquids from column '45 may be subjected to viscosity breaking conditions in this zone and to appreciable further vaporization, leaving a residual liquid product in chamber |3 of relatively high boiling characteristics, low B. S. content and relatively low gravity and which is suitable for sale as fuel oil. In case additional relatively mild cracking or viscosity breaking of the relatively heavy oils in column 45 is desired they may be passed through heating coil 12, prior to commingling with the heated products from heating coil 4| and subjected therein to a relatively mild conversion temperature, preferably at superatmospheric pressure, by means of heat supplied from furnace I3.

When it is desired to produce liquid residue of suitable fuel oil characteristics in chamber |3 and the volume of heated products from heating coil 42 relative to the volume of relatively heavy oils in column 45 is large, additional cooling of the heated products from'heating coil 4|, prior to commingling the same with said high-boiling I her l3. This may be accomplished in any desired well known manner, such as indirect heat exchange between the heated products from heating coil 4| and a-relatively cool oil such as charging stock for the process or any of the various intermediate liquid products, or a suitable cooling material may be introduced directly into line 43 to commingle with the heated products passing therethrough, by means of line 8| and valve 82. Any suitable oil may be employed for this purpose such as, for example, selected intermediate liquid products from either or both of the fractions or'regulated quantities of the distillate from either receiver 56 or receiver 22, or both. Both of these auxiliary methods of cooling are now well known in the art and for the sake of simplicity the required pumps and connecting lines for supplying the cooling medium to line 43 or to a suitable heat exchanger therein are not illustrated in the drawing.

In case it is desired to produce coke in chamber l3 as a residual product of the process and the volume and temperature of the heated products discharged from heating coil 4| is sumcient to effect coking of the high-boiling oils from column 45, additional cooling in line 43 may be dispensed with and said heated products and high-boiling oils commingle either in line 68 or in chamber |3 to effect coking of the high-boiling oils in this zone. In case there is not sufiicient heatavailable in the heated products from coil 4| to effect the desired coking of the high-boiling oils in chamber l3 or in case it is desired to produce a coke of exceptionally low volatility it is within the scope of the invention to quickly heat the high-boiling oils from column in heating coil 12 to a temperature sufiicient to induce such coking in chamber |3 without allowing the heavy oils to remain in heating coil 12 and the communicating line for a sufficient length of time to permit any substantial formation and deposition of coke prior to their introduction into chamber l3.

As already indicated, chamber |3, depending upon the type of residual product which it is desired to produce in this zone, may be operated either as a vaporizing and separating chamber or as a coking zone and the pressure employed in this zone may be varied from substantially the same as that employed at the outlet from heating coil 4| down to substantially atmospheric pressure although chamber I3 is preferably operated'at a somewhat higher pressure than that employed in chamber 5 in order to permit supplying the vapors from chamber l3 to chamber 5 without the use of a pump or compressor.

When chamber i3 is operated for the production of liquid residue the latter may be. withdrawn from the lower portion of the chamber through line 83 and valve 84 to cooling and storage or elsewhere, as desired.

When chamber i3 is operated as a coking zone the coke may be allowed to accumulate therein until the chamber is substantially filled or until its operation has been completed for any other reason, following which the coke may be removed in any well known manner, not illustrated, and the chamber cleaned and prepared for further operation. A plurality of coking chambers may, of course, be employed, when desired, although not illustrated in the drawing, and in such cases the chambers preferably are alternately operated. cleaned and prepared for further operation in order that this stage, in common with the rest of the system, may be operated continuously.

Vaporous products are removed from the upper portion of chamber l3 and directed through line 85 and valve 86 into chamber 5 wherein they commingle with the vaporous components of the conversion products supplied to chamber 5 from heating coil i and are subjected to further treatment therewith in the manner already described.

The preferred range of operating conditions which may be employed, in an apparatus such as illustrated and above described, to accomplish the desired results may be approximately as follows: The distilling and fractionating column,

although preferably operated at substantially atmospheric or relatively low superatmospheric pressure, may employ any desired superatmospheric pressure up to substantially the same as that utilized as the outlet from the cracking coil supplyingheated products thereto. The cracking coil to which intermediate fractions from the distilling or fractionating column are supplied may utilize an outlet'conversion temperature ranging, for example, from 850 to 950 F., or more, preferably with a superatmospheric pressure at this point in the system of from 200 to 800 pounds, or more, per square inch. The succeeding chamber may be operated at any desired pressure ranging from substantially the same as that employed at the outlet from the communicating heating coil down to 'substantially atmospheric pressure and, the pressure employed in this zone may be. either substantially equalized or somewhat reduced in the succeeding fractionating, condensing and collecting equipment. The heating coil to which the total or high-boiling fractions of the reflux condensate from the fractionator of the first cracking stage are supplied may utilize an outlet conversion temperature ranging, for example, from 800 to 950 F., or more, preferably with a superatmospheric pressure measured at the outlet fromthe heating coil of from 100 to 500 pounds, or thereabcuts, per square inch. When a separate cracking coil is employed for the overhead distillate product from the distilling and fractionating column and/or low-boiling fractions of the reflux condensate from the fractionator of the first cracking step, the temperature employed at the outlet therefrom may range, for example, from 900 to 1,050 E, or thereabouts, preferably with a superatmospheric pressure measured at the outlet from the heating coil of from 200 to 1,000 pounds per square inch and, depending upon the type of operation employed in the succeeding chamber, these products may be cooled, prior to their introduction thereto, to any desired temperature ranging from 900 1!, or more, down to 650 E, or thereabouts or may be supplied to the chamber without intentional cooling. When a heating coil is employed for the heavy liquid products from the distilling and fractionat-Q ing column the temperature employed at the outlet therefrom may range, depending upon the type of operation desired, from 750 to 1,000" F., or therabouts, with any desired pressure in this zone ranging from substantially atmospheric or relatively low superatmospheric pressure up to 300 pounds, or more, per square inch. When coking of the heavy liquid products from the distilling and fractionating column is employed the coking chamber preferably utilizes a superatmospheric pressure of from to 150 pounds, or thereabouts, per square inch and pressures of substantially the same or of a higher order may be employed in the vaporizing and separating chamber to which the heavy liquids from the distilling and fractionating column are supplied when this zone is operated for the production of liquid residue.

As a specific example of one of the many possible operations of the process, the charging stock, which comprises a Mid-Continent mixed base crude of approximately 36 A. P. I. gravity and contains approximately 27 per cent of straight-I run gasoline boiling up to approximately 400 F., but of inferior antiknock value, is separated by fractional distillation, together with conversion products resulting from cracking the high-boiling.

fractions of the reflux condensate from the fractionator of the first cracking step, into a lowboiling distillate of approximately 450 F. endboiling point, high-boiling residual oils and intermediate fractions. The intermediate frac-, tions are supplied to the heating coil of the first cracking stage, wherein'they are subjected to an outlet conversion temperature of approximately 950 F. at a superatmospheric pressure of about 350 pounds per square inch, and the heated products are discharged into a separating chamber maintained at a superatmospheric pressure of approximately pounds per square inch. The

resulting non-vaporous liquid residue is recovered as a final product of the process and the vapors are subjected to fractionation for the formation of low-boiling and high-boiling reflux condensates and the recovery of an overhead distillate product comprising materials within the boiling range of motor fuel and of good antiknock value. The high-boiling fractions of said reflux condensate are supplied to the heating coil of the second cracking stage of the system wherein they are subjected to an outlet conversion temperature of approximately 920 F. at a superatmospheric pressure of about 200 pounds per square inch and the heated products from this zone are introduced into the distilling and fractionating column to which the charging stock is supplied. The overhead distillate product from the distilling and fractionating step is subjected in a reforming coil, together with the low-boiling fractions of said reflux condensate, to an outlet conversion temperature of approximately 970 F. at a superate mospheric pressure of about 700 pounds per square inch. The highly heated products from the reforming coil and the residual liquids from the distilling and fractionating column are supplied to a coking chamber wherein the high-boilng oils are reduced to coke. The coking chamber is operated at a superatmospheric pressure of approximately pounds per square inch and the vaporous products from this zone are supplied to mamas the separating chamber of the first cracking step. This'operation will produce per barrel of charging stock, approximately 65 per cent of motor fuel of high antiknock value, approximately pounds of low volatile coke and about 7 per cent of good quality fuel oil, the remainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

1. In a process for the pyrolytic conversion of hydrocarbon-oils wherein oil of relatively lowboiling characteristics, recovered from within the system, is subjected to conversion conditions of cracking temperature and superatmospheric pressure, the resulting vaporous and residual liquid conversion products separated, the vapors subjected to fractionation for the formation of reflux condensate, fractionated vapors of the desired end-boiling point subjected to condensation and the resulting distillate recovered, the improvement which comprises separately subjecting reflux condensate formed by said fractiona-' tion to independently controlled conversion conditions of cracking temperature and superatmospheric pressure, ccmmingling the resulting heated products with hydrocarbon oil charging stock for the process, separating the commingled materials, by vaporization and fractionation, into selected relatively low-boiling, intermediate and high-boiling fractions, supplying said intermediate fractions to the flrst mentioned cracking step, subjecting the normally condensable components of said low-boiling fractions to reforming conditions of high cracking temperature and super- -atrnospheric pressure, commingling the resulting highly heated products with said high-boiling fractions whereby to reduce the latter to coke in a coking zone, and supplying vaporous products from the coking zone to the separating stage of the first mentioned cracking step.

2. In a process for the pyrolytic conversion of hydrocarbon oils wherein oil of relatively lowboiling characteristics, recovered from within the system, is subjected to conversion conditions of cracking temperature and superatmospheric pressure, the resulting vaporous and residual liquid conversion products separated, the vapors subjected to fractionation for the formation of reflux condensate, fractionated vapors of the desired end-boiling point subjected to condensation and the resulting distillate recovered, the improvement which comprises separately subjecting reflux condensate formed by said fractionation to independently controlled conversion conditions of cracking temperature and superatmospheric pressure, commingling the resulting heated products with hydrocarbon oil charging stock forthe process, separating the commingled materials, by vaporization and fractionation, into selected relatively low-boiling, intermediate and high-boiling fractions, supplying said intermediate fractions to the first mentioned cracking step, subjecting the normally condensable components of said low-boiling fractions to reforming conditions of high cracking temperature and superatrnospheric pressure, commingling the resulting highly heated products with said high-boiling fractions whereby to partially cool the former and subject the latter to viscosity breaking, separating the resulting vaporous and residual liquid components of the commingled materials, recovering the latter, and supplying said vaporous components to the separating stage of the first mentioned cracking step.

3. In a process for the pyrolytic conversion of hydrocarbon oils wherein oil of relatively lowboillng characteristics, recovered from within the system, is subjected to conversion conditions of cracking temperature and superatmospheric pressure, the resulting vaporous and residual liquid conversion products separated, the vapors subjected to fractionation for the formation of reflux condensate, fractionated .vapors of the desired end-boiling point subjected to condensation and the resulting distillate recovered, the improvement which comprises separately subiecting reflux condensate formed by said fractionation to independently controlled conversion conditions of cracking temperature and superatmospheric pressure, commingling the resulting heated products with hydrocarbon oil charging stock for the process, separating the commingled materials, by vaporization and fractionation, into selected relatively low-boiling, intermediate and high-boiling fractions, supplying said intermediate fractions to the first mentioned cracking step, recovering as said low-boiling fractions materials within the boiling range of motor fuel, subjecting said high-boiling fractions to coking in a separate coking zone, and supplying vaporous products from the coking zone to the separating stage of the flrst mentioned cracking step.

4. A process such as claimed in claim 3 wherein residual liquid of fuel oil characteristics is re-. covered from the separating stage of the first mentioned cracking step.

5. A process such as claimed in claim 3 wherein residual liquid conversion products are removed from the separating stage of the first mentioned cracking step and supplied to the coking zone.

6. A process such as claimed in claim 3 wherein said reflux condensate supplied to the second mentioned cracking step comprises high-boiling components of the total reflux condensate formed in the fractionating stage of the first mentioned cracking step and selected lower boiling fractions independently controlled conversion conditions of cracking temperature and superatmospheric pressure and the resulting highly heated products co'mmingled with said high-boiling fractions in the coking zone to assist the coking operation.

'7. In a process for the pyrolytic conversion of hydrocarbon oils wherein oil of relatively lowboiling characteristics, recovered from Within the system, is subjected to conversion conditions of cracking temperature and superatmospheric pressure, the resulting vaporous and residual liquid conversion products separated, the vapors subjected to fractionation for the formation of reflux condensate, fractionated vapors of the desired end-boiling point subjected to condensation and the resulting distillate recovered, the improvement which comprises separately subjecting reflux condensate formed by said fractionation to independently controlled conversion conditions of cracking temperature and superatmospheric pressure, commingling the resulting heated products with hydrocarbon oil charging stock for the process, separating the commingled materials, by vaporization and fractionation, into selected relatively low-boiling, intermediate and high-boiling fractions, supplying said intermediate fractions to the first mentioned cracking step,

I of the total reflux condensate are subjected to the resulting mixture, and supplying said vaporous components to the separating stage of the first mentioned cracking step.

8. A process such as claimed in claim 7 wherein said reflux condensate supplied to the second mentioned cracking step comprises high-boiling components of the total reflux condensate formed in the fractionating stage of the first mentioned cracking step and selected lower boiling fractions of the total reflux condensate are supplied to the same cracking step wherein the normally liquid components of said low-boiling fractions are subjected to reforming.

9. A conversion process which comprises cracking a hydrocarbon distillate and fractionating and condensing resultant cracked vapors, independently cracking reflux condensate formed by the fractionation and commingling resultant heated conversion products with charging oil for the process, separating the mixture of charging oil and conversion products into vapors and unvaporized oil, condensing the former and supplying at least a portion of the resultant condensate to the first-mentioned cracking step as said hydrocarbon distillate, vaporizing a substantial portion of said unvaporized oil and combining resultant vapors with the first-named vapors for fractionation in admixture therewith.

10. The process as defined in claim 9 further characterized in that the second-mentioned vapors are fractionally condensed into a gasolinelike condensate and a heavier reflux condensate, the latter being supplied to the first-mentioned cracking step as said hydrocarbon distillate.

11. The process as defined in claim 9 further characterized in that the: second-mentioned vapors are fractionally condensed into a gasoline-like condensate and a heavier reflux condensate, the latter being supplied "to the firstmentioned cracking step as said hydrocarbon distillate and the former being reformed, at least in part, for enhancement of anti-knock value and then contacted with said unvaporized oil to assist the vaporization of the latter.

12. A conversion process which comprises topping and fractionating crude petroleum to form topped crude, a. light distillate fraction containing the low anti-knock gasoline components of the crude, and an intermediate distillate fraction, cracking said intermediate fraction thereby forming vapors, independently reforming said light fraction and then contacting the same with the topped crude to vaporize portions of the latter, combining vapors from this contacting step with the first-named vapors, and fractionating and condensing the resultant vaporous mixture, subjecting reflux condensate formed by the last-mentioned fractionation to cracking conditions of temperature and pressure and commingling resultant heated products with the crude petroleum to assist the topping of the latter.

13. A hydrocarbon oil conversion process which comprises subjecting reflux condensate in a heated coil to cracking conditions of temperature and pressure and commingling resultant heated products with charging oil for the process, fractionating the resultant mixture to form a residual fraction, a light fraction and an intermediate fraction, subjecting the light and intermediate fractions to independently controlled cracking conditions of temperature and pressure in separate heating coils, contacting heated conversion products of the light fraction with said residual fraction and vaporizing a substantial portion of the latter, fractionating the vaporous products of this contacting step and thevaporous conversion products of said intermediate fraction and supplying resultant reflux condensate to the flrst- 5 named coil, and finally condensing the fractionated vapors.

14. A hydrocarbon oil conversion process which comprises subjecting reflux condensate in a heating coil to cracking conditions of temperao ture and pressure and commingling resultant heated products with charging oil for the process, fractionating the resultant mixture to form a. residual fraction, a light fraction and an intermediate fraction, subjecting the light and in- 15 termediate fractions to independently controlled cracking conditions of temperature and pressure in separate heating coils, contacting heated conversion products of the light fraction with said residual fraction and vaporizing a substantial 2o portion of the latter, fractionating the vaporous products of this contacting step and the vaporous conversion products of said intermediate fraction to separate relatively heavy and light reflux condensates therefrom, supplying the heavy reflux condensate to the first-named coil, subjecting the light reflux condensate to further conversion together with said light fraction, and finally condensing the fractionated vapors.

15. A hydrocarbon oil conversion process ,30 which comprises subjecting reflux condensate in a heating coil to cracking conditions of temperature and pressure and commingling resultant heated products with charging oil for the process, fractionating the resultant mixture to form a residual fraction, a light fraction and an intermediate fraction, subjecting the light and intermediate fractions to independently controlled cracking conditions of temperature and, pressure in separate heating coils, contacting 4 heated conversion products of the light fraction with said residual fraction and vaporizing a sub-' stantial portion of the latter, combining vaporv ous products of this contacting step with vaporous conversion products of said intermediate fraction, fractionating the thus commingled vapors and supplying resultant reflux condensate to the first-named coil, and finally condensing the fractionated vapors.

heated products with charging oil'for the process,

fractionating the resultant mixture to form a residual fraction, a light fraction and an intermediate fraction, subjecting the light and intermediate fractions to independently controlled cracking conditions of temperature and pressure in separate heating coils, contacting heated conversion products of the light fraction with said residual fraction and vaporizing a substantial portion of the latter, combining vaporous prod-- ucts of this contacting step with vaporous conversion products of said intermediate fraction, fractionating the thus commingled vapors to separate relatively heavy and light reflux condensates therefrom, supplying the heavy reflux condensate to the first-named coil, subjecting the light reflux condensate to further conversion together with said light fraction, and finally condensing the fractionated vapors.

ALVIN ENGELSTEIN.

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