US2127014A - Conversion of hydrocarbon oils - Google Patents

Description

Aug. 16, 1938. K. SWARTWOOD El AL CONVERSION OF HYDROCARBON OILS Filed Marph 7, 1935 5 Sheets-Sheet l INVENTORS KENNETH SWART WOOD CHARLES H. ANGELL TORNEY 'Aug. 16, 1938. K. SWARTWOOD El AL 1 2,127,014

CONVERSION OF HYDROGARBON OILS Filed March 7, 1935 3 Sheets-Sheet 2 INVENTORS KENNETH SWARTWOOD FIG. 3 CHARLES H. ANGELL ATTORNEY Aug. 16, 1938.

K. SWARTWOOD ET AL 2,127,014

CONVERSION OF HYDROCARBON OILS Filed March 7, 1955 s Sheets-Sheet s 27 2|\ 25 so [2 l 5 24 55 4Q 67 I6 64 l 56 4| l 53 l 4 a 6 63 as. 42

u 25 |4 I9 u 2 INVENTORS KENNETH SWARTWOOD CHARLES H. ANGELL FIG. 5 M ATTORNEY Patented Aug. 16, 1938 CONVERSION OF HYDROCARBON OILS Kenneth Swartwood and Charles H. Angell, Chicago, Ill., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application March 7, 1935, Serial No. 9,740

at substantially reduced pressure followed by coking of the residual liquids remaining unvaporized by'saidflash distillation. The invention is not limited'to any specific methodof coking the residual oils although it is particularly well adapted to operations of the type wherein the residual oils to be coked are subjected, in a heating coil, to a relatively'high temperature sufiicient to efiect their subsequent reduction to coke, in a coking chamber, without allowing the oil to remain in the heating coil and communicating lines for a sufficient time to permit the excessive formation and deposition of coke therein, since this type of coking operation involves the use of relatively high coking temperatures and the temperature of the resulting vaporous products may be substantially the same or even higher than the temperature maintained in the reaction chamber, thereby insuring their appreciable continued conversion in this zone and, in many cases, providing additional heat for further conversion of the vaporous products from the heating coil of the cracking system with which they are commingled in the reaction chamber. The process of the present invention is also well adapted to coking operations of the type wherein a heat-carrying medium such as highly heated intermediate or final low-boiling products of the operation or hydrocarbons from a suitable external source are introduced into the coking chamber to commingle with and effect reduction of residual liquid conversion products to coke.

In one embodiment, the invention comprises subjecting hydrocarbon oil to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating enlarged reaction chamber, separating the vaporous and residual liquid conversion products, subjecting the latter to further vaporization at substantially reduced pressure, heating the remaining non-vaporous residual liquid conversion products in a separate heating coil to a tempera ture sufliciently high to efiect their subsequent reduction to coke without allowing them sufiicient time in the heating coil to permit any excessive formation and deposition of coke in this zone, introducing the resulting highly heated residual oil in a coking chamber maintained at substantial superatmospheric pressure wherein their reduction to coke is accomplished, withdrawing hot vaporous products from the coking chamber and introducing the same into said reaction chamber tocommingle with the vaporous products from the first mentioned heating coil and be subjected to continued conversion therewith, subjecting the vaporous conversion products of the process, in-

8 Claims.

This invention particularly refers to an improved process for the pyrolytic conversion of hydrocarbon oils to produce high yields of desirable light distillate products such as motor fuel of good antiknock value, wherein the residual liquid conversion products of the process are reduced to substantially dry coke in a zone separate from that wherein the residual liquids are first separated from the vaporous conversion products; the present invention providing for continued conversion, at substantial superatmospheric pressure, of the hot vaporous products evolved during the coking operation for the two-fold purpose of increasing the yields of desirable light liquid products, such as motor fuel, and improving the quality of any components of the vapors Within the boiling range of motor fuel, particularly with respect to their antiknock value.

The present invention not only provides for continued conversion of the hot vaporous products from the coking operation but also provides for commingling these materials during said continued conversion thereof with the hot vaporous products from the heating coil of the cracking system. This method of operation is particularly advantageous in operations of the type wherein the residual liquid conversion products of the process are subjected to coking at a higher temperature than that ordinarily maintained in the reaction chamber to which the stream of heated products from the heating coil of thesystem is supplied, since, in such cases, the vaporous products from the coking operation may serve as a means of supplying additional heat to the vaporous products from the heating coil whereby to efiect additional conversion of the latter under conditions suitable for the production of high yields of motor fuel of good antiknock value. On the other hand, when higher temperatures are maintained in the reaction chamber than in the coking zone the method of operation of the present invention provides for additional heating of the vaporous products from the coking zone by being commingled in the reaction chamber with the more highly heated vaporous products from the heating coil thereby insuring sufiicient further conversion of the vaporous products from the coking zone to effect the production of additional yields of motor fuel of good antiknock value.

The present invention contemplates the coking of residual liquids, produced by the cracking operation and separated from the vaporous conversion products in the high-pressure reaction chamber of the system, or for flash distillation of the residual liquids Withdrawn from the reaction chamber cluding the vaporous products from the coking operation after said continued conversion thereof, the vaporous products from the first mentioned heating coil after their passage through the reaction chamber and the vapors evolved by said further vaporization of the liquid conversion products from the reaction chamber, to fractionation whereby their insufficiently converted components are condensed as reflux condensate, returning the reflux condensate to the first mentioned heating coil for further conversion, subjecting fractionated vapors of the desired end-boiling point to condensation and collecting and separating the resulting distillate and gas.

Various modifications of the specific embodiment of the present invention above outlined are possible within the scope of the present invention, some of which modifications are illustrated in the accompanying diagrammatic drawings and Will be described in conjunction with the following description of the drawings. The alternative methods of operation illustrated and described are not, however, to be considered equivalent but are intended to increase the flexibility of the process and may be selected to suit requirements.

Fig. 1 of the drawings illustrates an apparatus wherein equipment and connecting lines are provided to permit any of the various alternative methods of operation illustrated in Figs. 2, 3, 4 and 5, as Well as some additional alternative combinations not separately illustrated.

Figs. 2, 3, 4 and 5 are diagrammatic illustrations of alternative operations which can be practiced in the apparatus shown in Fig. 1.

The same reference characters are used to indicate corresponding portions of the apparatus in the various figures.

Referring now to Fig. 1: Hydrocarbon oil charging stock for the process may be supplied through line I and valve 2 to pump 3 by means of which it is fed through line 4 and may be directed, all or in part, through line 5 and valve 6 into fractionator 1. However, it may be supplied all or in part through lines 8 and 9, valve I and line II direct to the heating coil I2 or from line 9 through line 69 and valve III into chamber 21, or through valve I3 in line 8 and through line I4 to heating coil I5. The charging stock may, of course, be preheated to any desired degree, prior to its introduction into heating coil I2 or I or into fractionator 1 or chamber 21, by any well known means, not shown in the drawings.

When charging stock is supplied to fractionator I, in the manner illustrated and described, it is directly commingled in this zone with the vaporous conversion products undergoing fractionation therein, serving to assist their fractionation and being preheated by contact therewith and the preheated charging stock, or at least that portion of the charging stock remaining unvaporized in the fractionator or recondensed in this zone, is collected in its lower portion, together with the reflux condensate comprising the insufficiently converted components of the vaporous conversion products condensed in the fractionator, to be withdrawn therefrom through line I6 and valve IT to pump I8, by means of which this material is supplied through line I I and valve I9 to conversion in heating coil I2.

A furnace of any suitable form supplies the required heat to the oil passing through heating coil I2 to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure, and the stream of heated products is discharged from heating coil I2 through line 2i and valve 22 into reaction chamber 23.

Chamber 23 is also preferably maintained at a substantial superatmospheric pressure and, although not indicated in the drawings, this zone is preferably insulated in order to minimize the loss of heat therefrom by radiation so that conversion of the heated products supplied to this zone may continue therein. In accordance with one method of operation of the process of the present invention both vaporous and liquid conversion products may be withdrawn in commingled state from the lower portion of chamber 23 through line 24 and may be directed therefrom through line 25 and valve 26 into vaporizing chamber 21, wherein the vaporous and liquid conversion products are separated and the latter are subjected to further vaporization by virtue of the reduced pressure employed in this zone relative to that maintained in the reaction chamber. It is also within the scope of the present invention to effect substantial separation of vaporous and liquid conversion products in chamber 23 and to separately withdraw these materials therefrom, in which case the liquid conversion products are preferably withdrawn from the lower portion of the chamber through line 24 while the vaporous products may be withdrawn at any desired point or plurality of points in the reaction chamber above the point of removal of the residual liquid. In the case here illustrated, vaporous conversion products may be separately withdrawn from chamber 23 through line 28 and valve 29 and may be directed, all or in part, therefrom through line 30 and valve 3I into vaporizing chamber 21, entering this zone at any desired point, or the vaporous products from chamber 23 may be directed, all or in part, through Valve 32 in line 28 to fracitionation in fractionator I, being supplied to this zone either alone or together with vaporous products from chamber 21 which may be supplied, for example, from the upper portion of the vaporizing chamber through line 33 and valve 34 into line 28.

In case vaporous and liquid conversion products are separately removed from chamber 23 all or a regulated portion of the residual liquid conversion products may, when desired, be directed through valve 35 in line 24 to pump 36 by means of which they are fed through line 31, valve 38 and line I4 to heating coil I5. In case the liquid conversion products from chamber 23 are directed, either alone or together with all or a portion of the vaporous conversion products from this zone, to vaporizing chamber 21, in the manner previously described, the residual liquid remaining unvaporized in chamber 21 may be withdrawn from the lower portion thereof through line 40 and all or a regulated portion thereof may be directed through valve M in this line to pump 42 by means of which it is fed through line I4 and valve 43 to heating coil I5. When desired, instead of being supplied to heating coil I5, residual liquid from chamber 23 may be diverted from line 31 through line 44 and valve 45 and supplied through line 46 to coking chamber 41. In the same manner residual liquid from chamber 21 may be directed, when desired, to coking chamber 4! by means of line 48, valve 49 and line 46.

When all or a regulated portion of the charging stock for the process is supplied, as previously described, to vaporizing chamber 21 it is subjected to vaporization in this zone by contact with the hot vaporous products in the chamber, serving -f.

as a means of partially cooling the vapors and assisting in controlling the characteristics of both the vaporous and residual liquid conversion products recovered from chamber 21. Low-boiling components of the charging stock which are vaporized in chamber 21 pass, together with the vaporous conversion products from this zone, to fractionation in fractionator 1. Any high-boiling fractions of the charging stock remaining unvaporized in chamber 21 commingle with the residual liquid converison products in this zone and are subjected to further treatment therewith.

It is also within the scope of the present invention to produce both liquid residue and coke as final products of the process in which case all or a regulated portion of the liquid conversion products from chamber 23 remaining unvaporized in chamber 21 may be withdrawn from the system, by means of line 40, line 61 and valve 68, to cooling and storage or elsewhere, as desired. However, in all cases, a portion at least of the residual liquid from chamber 23 or from chamber 2? is supplied to coking chamber 41 either directly or though heating coil l5.

Heating coil I5 is located within a furnace 50, of any suitable form, by means of which the oil supplied to the heating coil is heated to a relatively high temperature, and the stream of highly heated oil is directed through line 5|, valve 52 and line into coking chamber 41, being supplied to this zone at any desired point or plurality of points therein, although only one point of introduction is illustrated in the drawings. In case charging stock is supplied to heating coil l5, as in the manner previously described, it preferably comprises a relatively high-boiling oil such as heavy crude or topped crude, residual oil or the like which it is desired to subject to coking and heating coil l5, together with furnace 50, preferably comprises a zone wherein the relatively heavy oils supplied thereto are subjected to high rates of heating for a relatively short time whereby they are quickly heated to a sufliciently high temperature to effect their subsequent reduction to coke in chamber 41 without allowing the oil sufficient time in the heating coil and communicating lines to permit any excessive formation and deposition of coke therein.

It is, however, also within the scope of the present invention, particularly in case residual liquid from chamber 23 or from chamber 21, as the case may be, is not supplied to heating coil l5, to utilize a heating coil, which may be represented diagrammatically by the same coil l5, for the heating of charging stock for the process, comprising any desired type of oil, or for the heating of liquid, vaporous or gaseous products of the process such as, a portion or all or selected fractions of the intermediate conversion products of the process, recovered by fractionation of the vaporous products in fractionator I, or regulated portions of the light distillate or of the gaseous products of the process. In such cases the oil supplied to heating coil I5 is preferably heated to a relatively high conversion temperature and either commingled in line 45 with the residual liquid conversion products of the process and supplied therewith to chamber 41 or the stream of highly heated products from heating coil I5 may be separately supplied to the coking chamber at any desired point or plurality of points in this zone. This particular method of coking is not in itself new with the present invention and for the sake of simplicity all of the various well known provisions for accomplishing the same are not indicated in the drawings.

Coking chamber 41 is preferably operated at a substantial superatmospheric pressure, which may be only slightly or appreciably higher than the pressure maintained in reaction chamber 23, in order to permit the introduction of hot vaporous products from the coking chamber into chamber 23 by way of line 53 and valve 54 without the aid of a pump or compressor. However, the invention also contemplates the use of relatively low superatmospheric, substantially atmospheric or even sub-atmospheric pressure in the coking zone in which case a vapor pump or compressor or the like not illustrated will, of course, be required to transfer the hot vaporous products from chamber 4'! to the high-pressure reaction chamber 23.

The vaporous products from coking chamber 47 commingle in chamber 23 with the hot vaporous products from heating coil l2, supplied to this zone as previously described, and the commingled materials are subjected to continued conversion in the reaction chamber.

The coke produced in chamber 4! may be allowed to accumulate within this zone to be removed therefrom, in any suitable well known manner, not illustrated, after the operation of the chamber is completed. It is within the scope of the present invention, when desired, to employ a plurality of coking chambers similar to chamber 41, but not illustrated, which preferably are alternately operated, cleaned and prepared for further operation, so that the duration of the operating cycle of the process is not limited by the capacity of the coking zone. Chamber 4! is provided with a suitable drain-line 55 controlled by valve 56 which may also serve as a means of introducing steam, water or any other suitable cooling medium into the chamber after its operation is completed and after it has been isolated from the rest of the system in order to hasten cooling and facilitate the removal of coke from the chamber.

The vaporous products of the process supplied to fractionator 1 from vaporizing chamber 21 and/or reaction chamber 23, in the manner previously described, including the vaporous products from coking chamber 4'! which have been subjected to continued conversion in chamber 23, are separatedby fractional condensation in this zone into lowboiling fractions of the desired characteristics, preferably comprising materials within the boiling range of motor fuel and of good antiknook value, and insufficiently converted higher boiling components. The latter are condensed as reflux condensate and returned, as pre' viously described, to further conversion in heating coil l2 while the former, comprising fractionated vapors of the desired end-boiling point, are withdrawn, together with uncondensable gas produced by the process, from the upper portion of fractionator I through line 51 and valve 58 and are subjected to condensation and cooling in condenser 59. The resulting distillate and gas is directed through line 60 and valve iii to collection and separation in receiver 62. Uncondensable gas may be released from the receiver through line 63 and valve 54. Distillate may be withdrawn from receiver 62 through line 65 and valve 66 to storage or to any desired further treatment.

When desired, a regulated portion of the dis-' tillate collected in receiver 62 may be recirculated, by Well known means, not illustrated, to the upper portion of fractionator I to serve as a cooling and refluxing medium in this zone for assisting fractionation of the Vapors and to maintain the desired vapor outlet temperature from the fractionator.

Although the flows shown in Figs. 2, 3, 4 and 5 are each illustrated in Fig. 1 and have each been described in conjunction with the foregoing description of Fig. 1, the following brief description of each of the Figs. 2, 3, 4 and 5 will facilitate a better understanding of some of the specific flows and types of operation to which the process is adapted.

Referring to Fig. 2, reflux condensate from fractionator I is passed through heating coil [2 and discharged therefrom, at the desired cracking temperature, into reaction chamber 23. Separation of Vaporous and residual liquid conversion products is accomplished in the chamber 23.

Residual liquid is withdrawn from chamber 23 and supplied to heating coil I5, wherein it is heated to a high temperature under non-coking conditions and from which the heated products are discharged into coking chamber 41 wherein their non-Vaporous high boiling components are reduced to coke. The coke produced is allowed to accumulate in chamber 41, and Vaporous products are directed from this zone to reaction chamber 23, wherein they are subjected to further cracking together with the heated products from heating coil I2.

Vaporous products are separately withdrawn from chamber 23 and directed to fractionator I, wherein their insufiiciently converted components are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling point are removed from the upper portion of fractionator I, subjected to condensation and cooling in condenser 59, and passed thence to receiver 62, wherefrom the resulting distillate and uncondensed gases are separately removed.

Charging stock for the process is supplied to pump 3, wherefrom it may be directed, depending upon its characteristics, either to fractionator I or direct to heating coil I2 or to heating coil I5. When the charging stock is a relatively heavy oil of high coke-forming characteristics it is preferably supplied to heating coil I5, but when the charging stock is an oil containing a substantial quantity of low boiling fractions, such as, for example, good quality gasoline, which it is desired to recover with the light distillate conversion product of the process in receiver 22, it is preferably supplied to fractionator I. In other cases it may be supplied either to fractionator I or direct to heating coil I2, or in part to each of these zones.

Referring now to Fig. 3, the charging stock, which may comprise either a relatively heavy oil of high coke-forming characteristics or an oilof lower boiling nature than that supplied to heating coil I2, and which may be advantageously subjected to a higher cracking temperature than that employed in heating coil I2, is directed to pump 3 and thence to heating coil I5. In either case the charging stock is preferably heated in coil I5 to a higher cracking temperature than that employed in heating coil I2, but when the charging stock is an oil of relatively low boiling characteristics it is preferably subjected to more prolonged cracking time in coil I5 than an oil of high boiling and higher coke-forming characteristics.

Heated products are discharged from heating coil I5 into coking chamber 41, wherein the high boiling, non-Vaporous components of the materials supplied thereto are reduced to coke. The cokeproduced is allowed to accumulate in chamber 41 and Vaporous products are directed from this zone to reaction chamber 23, wherein they commingle with the heated products supplied to this zone from heating coil I2 and are subjected to continued conversion therewith.

Reflux condensate from fractionator I is supplied to heating coil I2, wherein it is heated to the desired cracking temperature and wherefrom the resultant heated products are supplied to reaction chamber 23.

Vaporous and residual liquid conversion products are separated in chamber 23, the residual liquid being directed from the lower portion of this zone into line 46, wherein it commingles with and serves to partially cool the heated products discharged from heating coil I5 and is directed therewith to coking chamber 47!.

Vaporous products are separately withdrawn from chamber 23 and are directed to fractionation in fractionator I, wherein their insufliciently converted components are condensed as reflux condensate.

Fractionated vapors of desired end-boiling points are withdrawn from the upper portion of fractionator I, subjected to cooling and condensation in condenser 59, and the resulting distillate and uncondensed gases are collected in receiver 62, from which they are separately withdrawn.

It will be noted that in the type of operation illustrated in Fig. 3, the residual liquid from chamber 23 is subjected to coking in chamber 4! by means of heat supplied thereto by commingling it with the highly heated products from heating coil I5.

Referring now to Fig. 4, reflux condensate is supplied from fractionator I to heating coil I2, wherefrom it is discharged at the desired cracking temperature into reaction chamber 23.

Vaporous and liquid conversion products are, in the case here illustrated, withdrawn in commingled state from the lower portion of chamber 23 and directed to reduced pressure vaporizing chamber 21, wherein the liquid products are subjected to appreciable further vaporization.

A regulated portion or all of the non-Vaporous liquid residue withdrawn from the lower portion of chamber 21 may, when desired, be withdrawn from the system through line 61 and valve 68 to cooling and storage, or elsewhere as desired, or a regulated. portion or all of this material may be supplied by means of pump 42 to heating coil I5,

wherein it is quickly heated to a high cracking temperature under non-coking conditions and wherefrom the resultant heated products are introduced into coking chamber 41, their high boiling components being reduced in this zone to coke.

The coke produced is allowed to accumulate in chamber 41 and Vaporous products are supplied from this zone to reaction chamber 23, wherein they commingle with the heated products from heating coil !2 and are subjected therewith to continued conversion.

Vaporous products are directed from chamber 27 to fractionation in fractionator I, wherein their insufficiently converted components are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling points are directed from the upper portion of fractionator I to cooling and condensation in condenser 59 and the resulting distillate and uncondensed gases pass to receiver -62, wherefrom they are separately withdrawn.

Charging stock for the process is supplied to pump 3 and may be directed therefrom, depending upon its characteristics, either to fractionator 1, chamber 27, direct to heating coil l2, or direct to heating coil l5.

' When the charging stock is an oil of high boiling and high coke-forming characteristics and contains no appreciablequantity of low boiling fractions suitable for cracking in heating coil I2 it is preferably supplied to heating coil l5,-either alone or together with a portion or all of the liquid residue from chamber 21. When the charging stock contains an appreciable quantity of high boiling and high coke-forming materials, and also contains lower boiling fractions suitable for cracking in heating coil l2, it is preferably sup-- plied to chamber 21, wherein said high boiling components thereof are commingled with the residual liquid conversion product and supplied therewith, at least in part, to heating coil l5, while its lower boiling fractions are vaporized in chamber 21 and passed therefrom together with the vaporous conversion products of the process to fractionation in fractionator I. Whenthe total charging stock is suitable for cracking in heating coil l2 it may be supplied either direct to this-zone or to fractionator 1, or in part to both, but in case it contains desirable low-boiling fractions, such as, for example, gasoline of good anti-knock value, which it is desired to recover in receiver 62 together with the light distillate conversion products of the process, it is preferably supplied to fractionator 1.

Referring now to Fig. 5, reflux condensate from fractionator 'l is directed to heating coil l2, wherefrom it is discharged at the desired cracking temperature into reaction chamber 23 Both vaporous and liquid components of the oils supplied to chamber 23, after passing through this zone and being subjected to continued cracking therein, are removed, in the particular case here illustrated, in commingled state from the lower portion of chamber 23 and are introduced into reduced pressure vaporizing and separating chamber 21 whereintheir liquid components are subjected to appreciable further vaporization;

The residual liquid conversion products remaining unvaporized in chamber 21 are withdrawn from the lower portion of this zone, and, when desired, a regulated portion thereof may be withdrawn from the system through line 6'! and valve E8, to cooling and storage, or elsewhere as desired.

Charging stock for the process, which may comprise an oil of higher boiling and higher cokeforming characteristics than that. supplied to heating coil l2 and which may be advantageously subjected to less prolonged cracking time than the latter, or which may comprise a relatively low boiling oil suitable for subjection to an appreciably higher cracking temperature, and, when desired, to more prolonged conversion time than that employed in heating coil I2, is directed to pump 3 and supplied therefrom to heating coil l5.

The conditions employed in heating coil is will depend upon the nature of the chargingstock; low boiling charging stock ordinarily being subjected to higher cracking temperature, more pro- .longed cracking time, and, when desired, to a higher superatmospheric pressure in heating coil l than charging stock of higher boiling-and higher coke-forming characteristics.

The heated products are discharged from ,heat ing coil l5 and commingled in lin'eAl with at least a regulated portion of the non-vaporous liquid residue withdrawn from chamber 2?, whereby the liquid residue is heated to a temperature sufficient to induce its subsequent coking and the heated products from heating coil 15 are partially cooled, The commingled materials are directed through line 13 into coking chamber ll, wherein their nonvaporous, high-boiling components are reduced to coke.

The coke produced is allowed to accumulate in chamber 4? and the vaporous products are directed from this zone into chamber 23, wherein they commingle with the heated products supplied to this zone from heating coil l2 and are subjected therewith to continued cracking.

vaporous products of the process are directed from the upper portion of chamber 41 to fractionation in fractionator I, wherein their insufiiciently converted components are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling point are directed from the upper portion of fractionator l to cooling and condensation in condenser 59, the resulting distillate and uncondensed gases being supplied to receiver 62, wherefrom they are separately withdrawn.

It will be noted that in the process illustrated in Figs. 2 and 3 the reduced pressure vaporizing chamber 21 and the communicating lines are eliminated, thus materially simplifying the process; However, the use of chamber 2'?! in the manner illustrated and described is preferred in many instances, particularly in case it is desired to produce good quality liquid residue as a final product of the process, as well as coke. Furthermore, it is ordinarily advantageous, when liquid residue to be coked is supplied to heating coil iii, to substantially free the same of low-boiling components which would vaporize in the early stages of the heat treatment afforded in heating coil it, since excessive vaporization in this zone will often cause excessive coke formation and deposition therein. In the apparatus illustrated in Figs. 4 and 5 the reduced pressure vaporization afforded the liquid conversion products in chamber 2? serves to substantially free the same of undesirable low-boiling components.

In an apparatus of the character illustrated and above described the preferred range of operating conditions suitable for accomplishing the process may be approximately as follows: The first mentioned heating coil, to which reflux condensate from the fractionator of the system is supplied, may employ a conversion temperature, measured at the outlet therefrom, ranging, for example from 850 to 1000 F., preferably with a superatmospheric pressure, measured at this point in the system, of from 100 to 500 pounds, or there- .abouts, per square inch. Substantially the same or a somewhat reduced superatmospheric pressure may be employed in the reaction chamber. The coking chamber is preferably operated at a pressure sufficiently higher than that employed in the reaction chamber to permit the introduction of vapors from the coking chamber into the,

reaction chamber without the aid of a pump or compressor although, when desired, lower pressures down to substantially atmospheric or even sub-atmospheric pressure may be employed in the coking zone. The vaporizing chamber, when such a zone is employed, is preferably operated at a substantially reduced pressure relative to that employed. in the reaction chamber, ranging, for example, from 100 pounds per square inch, or thereabouts, superatmospheric pressure to substantially atmospheric pressure. The fractionat ing, condensing and collecting portions of the system may employ pressures substantially the same or somewhat lower than those employed in the preceding portion of the system but no greater than the pressure employed in the vaporizing chamber, when such a zone is utilized. When the residual liquid from the reaction chamber or vaporizing chamber is heated in a separate heating coil to efiect its subsequent reduction to coke the temperature employed at the outlet from this zone may range, for example, from 900 to 1050 F., or thereabouts, with a pressure, measured at the outlet from said separate heating coil, substantially the same or appreciably greater than the pressure employed in the coking chamber. In case light oils such as, for example, low-boiling charging stock, low-boiling fractions of the intermediate conversion products of the process (reflux condensate), or the like, are subjected to conversion in a separate heating coil and utilized as a heat-carrying medium for the coking operation, the temperature employed at the outlet from the heating coil may range, for example from 950 to 1100 F., or thereabouts, preferably with a substantial superatmospheric pressure at this point in the system of some 300 to 800 pounds, or more, per square inch although, when desired, lower pressures down to substantially atmospheric may be employed in this zone, particularly in case relatively high temperatures are utilized.

As a specific example of one of the many possible operations of the process as it may be accomplished in an apparatus of the character illustrated and above described, the charging stock is a Mid-Continent reduced crude of about 25 A. P. I. gravity which is fed to the fractionator of the system and supplied therefrom, together with the reflux condensate formed in this zone. to a heating coil wherein it is heated to an outlet conversion temperature of approximately 935 F, at a superatmospheric pressure of approximately 250 pounds per square inch. Both vaporous and liquid conversion products are withdrawn from the reaction chamber and introduced into a reduced pressure vaporizing chamber operated at a superatmospheric pressure of approximately 45 pounds per square inch, which is substantially equalized in the succeeding fractionating, condensing and collecting portions of the system, residual liquid remaining unvaporized in the vaporizing chamber is withdrawn therefrom and quickly heated in a separate heating coil to a temperature of approximately 980 F. and then introduced into a coking chamber, operated at a pressure slightly higher than that in the reaction cham ber, wherein the residual oil is reduced to coke. vaporous products from the coking chamber are returned to the reaction chamber wherein they are subjected to continued conversion together with the heated products from the first mentioned heating coil. This operation will produce, per barrel of charging stock, approximately 60 per cent of motor fuel having an antiknock value equivalent to an octane number of approximately '70 and approximately 80 pounds of low volatile coke of uniformly good quality, the remainder being chargeable, principally, to uncondensable gas.

We claim as our invention:

1. In a process for the conversion of hydrocarbon oils wherein an oil is subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, the resulting vaporous and liquid conversion products separated, the latter subjected to further vaporization at substantially reduced pressure, the resulting non-vaporous residual liquid heated to a high conversion temperature in a separate heating coil, without allowing it to remain in the heating coil for a sufficient time to permit appreciable coking therein, and the highly heated residual oil distilled to coke in a coking chamber operated at substantial superatmospheric pressure, the improvement which comprises withdrawing hot vaporous products from the coking chamber and introducing the same into said reaction chamber, wherein they commingle with the heated products from the first mentioned heating coil and are subjected therewith to continued conversion, subjecting the vaporous conversion products of the process to fractionation whereby their insufficiently converted components are condensed as reflux condensate, returning the reflux condensate to the first mentioned heating coil for further conversion, subjecting fractionated vapors of the desired endbolling point to condensation and collecting the resulting distillate.

2. A process for the conversion of hydrocarbon oils which comprises subjecting an oil to conversion temperature at superatmospheric pressure in a heating coil, introducing the heated products into an enlarged reaction chamber also maintained at superatmospheric pressure wherein their conversion is continued and wherein vaporous and liquid conversion products are separated, separately withdrawing vaporous and liquid conversion products from the reaction chamber, subjecting the latter to further vaporization in a reduced pressure vaporizing chamber, withdrawing the remaining non-vaporous residual liquid from the vaporizing chamber, supplying at least a' regulated portion of the same to a separate heating coil wherein it is heated to a high conversion temperature under non-coking conditions, discharging the highly heated materials from said separate heating coil into a coking chamber operated at substantial superatmospheric pressure and distilling the same therein to coke, returning hot vaporous products from the coking chamber to the reaction chamber wherein they commingle with the heated products from the first mentioned heating coil and are subjected therewith to continued conversion, subjecting vaporous products from the reaction chamber and from the reduced pressure vaporizing chamber to fractionation whereby their insufficiently converted components are condensed as reflux condensate, returning reflux condensate resulting from said fractionation to the first mentioned heating coil for further conversion, subjecting fractionated vapors of the desired endboiling point to condensation and collecting the resulting distillate.

3. A process of the character defined in claim 2 wherein a regulated portion of the non-vaporous residual liquid withdrawn from the vaporizing chamber is recovered as a final product of the process.

4. A process for the conversion of hydrocarbon oils which comprises subjecting an oil to conversion temperature at superatmospheric pressure in a heating coil, introducing the heated products into an enlarged reaction chamber, also maintained at superatmospheric pressure, wherein their conversion is continued and wherein vaporous and liquid conversion products are separated, separately withdrawing vaporous and liquid conversion products from the reaction chamber, subjecting a regulated portion of said liquid conversion products to further vaporization in a reduced pressure vaporizing chamber, withdrawing the remaining non-vaporous residual liquid from the vaporizing chamber, recovering at least a regulated portion thereof as a final product of the process, supplying the remaining portion of said liquid conversion products from the reaction chamber to a separate heating coil wherein they are quickly heated to a high conversion temperature without allowing the same to remain in the heating coil for a sufiicient time to permit appreciable coking therein, discharging the highly heated materials from said separate heating coil into a coking chamber operated at substantial superatmospheric pressure and distilling the same therein to coke, returning hot vaporous products from the coking chamber to the reaction chamber wherein they commingle with the heated products from the first mentioned heating coil and are subjected therewith to continued conversion, subjecting the vaporous conversion products from the reaction chamber and from the reduced pressure vaporizing chamber to fractionation whereby their insufficiently converted components are condensed as reflux condensate, returning reflux condensate resulting from said fractionation to the first mentioned heating coil for further conversion, subjecting fractionated vapors of the desired end-boiling point to condensation and collecting the resulting distillate.

5. A process of the character defined in claim 4 wherein a regulated portion of the non-vaporous residual liquid withdrawn from the vaporizing chamber is supplied to said separate heating coil together with said residual liquid products from the reaction chamber.

6. In a process for the conversion of hydrocarbon oils wherein an oil is subjected to conversion conditions of elevated temperature and superatmospheric pressure in a heating coil and communicating reaction chamber, both vaporous and liquid conversion products withdrawn from the reaction chamber in commingled state and introduced into a reduced pressure vaporizing chamber wherein final separation of vaporous and residual liquid conversion products is accomplished, the vaporous conversion products subjected to fractionation whereby their insufiiciently converted components are condensed as reflux condensate, fractionated vapors of the desired end-boiling point subjected to condensation, the resulting distillate collected and reflux condensate resulting from said fractionation returned to the heating coil for further conversion, the improvement which comprises withdrawing the residual liquid remaining unvaporized in the vaporizing chamber therefrom, subjecting at least a regulated portion thereof to a high conversion temperature in a separate heating coil under noncoking conditions, discharging the highly heated products from said separate heating coil into a coking chamber operated at substantial superatmospheric pressure and distilling the same therein to coke and returning hot vaporous products from the coking chamber to the reaction chamber wherein they commingle with the heated products from the first mentioned heating coil and are subjected therewith to continued conversion.

'7. A process of the character defined in claim 6 wherein a regulated portion at least of the hydrocarbon oil charging stock for the process is supplied to the vaporizing chamber.

8. A process of the character defined in claim 6 wherein a regulated portion of the non-vaporous residual liquid withdrawn from the vaporizing chamber is recovered as a final product of the process.

KENNETH SWARTWOOD. CHARLES H. ANGELL.

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