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June 21, 1938. w. F. MOORE ' 2,121,209 TREATMENT OF‘ HYDROCARBON OIL Filed April 19, 1933 163 INVENTOR ' ' W/LLHM E MOORE Btwww. 7% 128 ' - Y ATTORNEY 2,121,209 Patented June 21, 1938 UNITED STATES PATENT OFFICE 2,121,209 ' TREATMENT‘ or nrnnoomon on. William F. Moore, Bayside, N. Y., as‘sig-nor to Gasoline Products Company, Inc., Newark, 'N. J., a corporation of Delaware ' Application April 19, 1933, Serial No. 666,801 .5 Claims.“ (01. 196-49) This inventionv relates to they treatment of hydrocarbon oil, such as petroleum and oils de rived from petroleum, for the recovery there from of valuable low-boiling oils such as gaso 5 line- or motor fuel. My invention has for an object the provisionpf a process adapted to ob distillation under substantially non-cracking con ditions, the products being separated and frac tionated to recover a residual product or reduced crude, gas oil, virgin gasoline and gas, as well as such addition fractions, for example, lubricating oil stocks, as may 'be ‘produced according to the tain a maximum conversion of, a petroleum oil‘ nature of the original crude petroleum. Accord ' into valuable products more especially low-boil ing to one method of operation of my invention ing products such as gasoline or motor fuel, and , the virgin gas oil may then be cracked for the 10 to produce reduced amounts of \ relatively less purpose of recovering a cracked gasoline frac 10 valuable products such as gas and fuel oil or > tion, gases, recycle gas oil, and residual oil or tar. pressure tar, 'The gas oil thus produced may be My invention has for further objects such addi tional improvements in operative advantages and 15 results as may hereinafter be found to obtain. My invention contemplates a combined process wherein a petroleum oil, for example, a crude petroleum, may be distilled, with the selective 7 treatment of various products of the ‘distillation, '20 including pyrolysis or cracking of a suitable stock or stocks resulting from the distillation step, and further selective treatment and combination, under conditions favorable for inter-reaction and the formation of valuable products, of products 0 produced in the distilling and. cracking opera tions, as well as materials such as gas or oil which may be drawn from outside sources. ‘ More speci?cally, in one of its aspects my in vention contemplates the reforming of gasoline or naphtha of relatively low anti-knock value to produce a gasoline or naphtha product of im- H recycled in the cracking unit. The virgin gas oline from the initial distillation step may then be subjected to heat treatment to effect a refor 15 mation of constituents thereof to constituents of improved anti-knock value, while the reduced crude resulting from the initial distillation op eration may be subjected to a mild cracking temperature which may promote the formation ‘of unsaturated or other reaction constituents, and the hot reformed products together with the products from the cracking of the reduced crude may be discharged into a common reac tion zone which may also receive gases drawn 2 from the distillation or cracking stages or from~ outside sources, either with or without pyrolysis at high temperature to promote the formation of unsaturated hydrocarbon constituents. ' v'I'he various products delivered to the common reaction zone are- digested together under con- , proved anti-knock value and the combining of the resultant products with relatively heavy pe troleum oil, preferably a residual oil, and prefer ably ‘a hydrocarbon oil containing reactive constit uents, such, for example, as unsaturated hydro 'ditions favorable for inter-reaction between gas eous and liquid unsaturated hydrocarbons or carbons, in the presence of gaseous unsaturated gaseous constituents to normally liquid constit hydrocarbons such as ole?ns, resulting from the reformation ofthe naphtha or gasoline or de 40 rived from an external'source, under conditions other reactive constituents, and preferably with in a range of temperature and‘pressure e?ec 35 tive to promote the polymerization of normally 4 uents. The resultant vapors may then be with drawn and fractionated to recover ‘normally effective to promote polymerization of normally gaseous constituents to normally liquid constitu ents. ,The conditions under which the combine--v liquid and normally gaseous products therefrom, 40 more particularly, to effect the recovery of the gasoline or naphtha fraction. As an alternative mode of ‘procedure, I may tion is effected are so controlled as to cause subjectthe reduced crude or residual oil result 45 inter-reaction to take place between the gaseous ing from the initial ‘distillation step, together 45 products of the reforming operation, as well‘ as, with virgin gas oil, if so desired, to a cracking _ when-they are present, gaseous unsaturated hy operation of more or less conventional character drocarbons from outside sources, and relatively for the purpose of producing a cracked gasoline heavy liquid "constituents also present, thereby resulting in the formation of more or less inter distillate, and the various products resulting from the cracking operation, such, forexample, mediate products such as motor fuel, naphtha or ' as gas and residual oil or pressure tar may be gasoline or _oil suitable for cracking to produce combined in a common reaction zone, either with motor fuel or gasoline having an improved anti or without preliminary treatment under selected knock value. conditions to promote the formation of reactive _ Thus, I may subject a crude petroleum to constituents such as unsaturated hydrocarbons. 50' 2 2,121,209 In any case, I may conduct a cracking opera tion in such manner as to recover, in addition to a light cracked gasoline distillate, a heavy gasoline or naphtha fraction suitable for reform Cl ing, and I may subject this heavy gasoline frac tion to a reforming operation for the purpose of increasing its anti-knock value and its content of unsaturated hydrocarbons, the resultant re formed products being delivered to a reaction 10 Vessel which is supplied with a ‘relatively heavy petroleum oil of the character'indicated herein above. The resultant vapors are withdrawn and fractionated for the recovery of normally liquid \ constituents therefrom. I may also supply the gases liberated in the distilling stage, preferably supplemented by gases. drawn from the cracking stage or from an out side source, to the aforesaid reaction stage, and where such gases contain relatively small amounts of unsaturated constituents, they may be subjected to an initial pyrolysis for the pur pose of producing or increasing the amount of unsaturated hydrocarbons such as gaseous ole?ns. 25 In order that my invention may be clearly set forth and understood, I now describe, with ref erence to the drawing accompanying and form ing part of this speci?cation, various preferred forms and manners in which my invention may 30 be practiced and embodied, but without limiting my invention to such exempli?cations. In this drawing: The single ?gure is a more or less diagram matic view of a system for treating hydrocarbon 35 oil in accordance with my invention. Referring to the drawing, a petroleum oil, such, for example as a crude petroleum of Mid continent origin, is drawn from a source (not shown) through a conduit I, wherein is located a pump 2, by means of which the oil may be passed to a heat-exchange coil 3 located Within a fractionating tower 4, before passing through a conduit 5 to heating coils 6 and 'I located within a furnace 8. While in transit through the coils 6 and I, the 45 oil is heated to a su?icient temperature to effect the desired distillation, such for example, as from 600° to 750° F., and the heating of the oil may with advantage be conducted without any '50 material cracking. The heated oil then ?ows through a line 9 having a pressure-reducing valve In to a separating compartment II located in the bottom of the fractionating tower 4. The separating compartment I I may be provided with 55 suitable ba?ies I2, as well as a re?ux supply line I3, for the purpose of preventing entrainment-of heavy or residual constituents of the oil being distilled. The vapors liberated in the separating compartment; II pass upward through a trap 60 out tray I4 into the upper portion of the frac of virgin gasoline, is withdrawn through a con duit 21 having a valve 28. A portion of the gas oil withdrawn from the trap-out tray I4 may be employed as a re?ux either in the tower 4 or elsewhere. Thus, a portion of this gas oil may be withdrawn through a branch conduit 3| having a, valve 32 and com7 municating with the conduit I6, to pass through a cooler 33 and‘a conduit 34 having a valve 35, to the re?ux line I3, by means of which this 10 oil may be reintroduced into the separating chamber II. The virgin gas oil not employed as a re?ux may be delivered by the pump I8 through a con duit 36 having a valve 31, while the residual oil or reduced crude which separates in the bot tom of the separating compartment II may be withdrawn therefrom from a conduit 38 wherein is located a pump 39. In the drawing, I have illustrated a cracking 20 plant comprising principally a furnace M, a still 42 and a fractionating tower 43, which plant may be employed for cracking either virgin gas oil or reduced crude, or both. Thus, the virgin gas oil may be delivered by the pump I8 through 25 conduits I6, 36, 44 and 45 to heating coils 46, 41 and 48 located within the furnace 4I, wherein the gas oil is heated to any suitable cracking temperature such, for example, as from 850° to 1050° F. under such superatmospheric pressure 30 as may be desired. When using a very clean ~stock the cracking may be carried on in the vapor phase. The resultant hot cracked prod ucts are then discharged through a transfer-line 5| to the still 42, which may receive reduced 35 crude from the pump 39 and conduit 38 through a branch conduit 52 having a valve 53 and lead ing to-an intermediate portion of the still 42. The still 42 may be provided, as shown, with ba?ies 54 and may also receive cool re?ux oil, 40 preferably at a point above the point of admis sion of the reduced crude thereto. For example, such re?ux oil may be supplied from the pump I8 and the cooler 33 through a conduit 55 having a valve 56. Within the still 42, separation of vapors and residual oil takes place, the vapors passing through a vapor line 51 to the fractionating tower 43, while the residual liquid is withdrawn from the bottom of the still 42 through a conduit 58 wherein is located a pump 59 and a valve 60. In some instances, as for example when reduced crude is not charged to the still 42, it may be desirable to withdraw the residual oil or pressure tar from the bottom of the still 42 to remove it from‘ the system. In other instances, such re sidual oil may be withdrawn through a branch conduit I52 having a valve 63. Within the fractionating tower 43, which is preferably provided with plates or trays 64 and 60 a cooling coil 65, the vapors withdrawn from tionating tower 4, which is provided with suitable plates or trays I5, and under the in?uence of the ‘the still 42 are subjected to a fractional con densation, which is carried out in such manner heat-exchange coil 3, a dephlegmating and frac as to effect the condensation and accumulation tionating action takes place, resulting in the con at the bottom of the fractionating'tower 43 of a 65 65 densation of a gas ‘oil fraction which collects at the trap-out tray I4 and is withdrawn from the gas-oil fraction which is preferably withdrawn from the tower 43 through a conduit 66 having fractionating tower 4 through a conduit I6 hav ing a valve I1 and a pump I8. The gases and vapors reaching the top of the 70 fractionating tower 4 pass through a vapor line 2I, a condenser 22 and a condensate line 23 to a gas separator 24, where a separation of con densate and uncondensible gas is effected. The gases are withdrawn through a conduit 25 hav 75 ing a valve 26 while the condensate, consisting a valve 61 and a pump 68. This gas oil may be recycled through the coils 46, 4'! and 48 lo-' cated within the furnace 4!. Gases and vapors 70 reaching the top of the fractionating tower 43 are withdrawn through a vapor line ‘II to a con denser ‘I2 from which the condensed products pass through a conduit ‘I3 to a gas separator ‘I4. The condensate, consisting of light cracked dis 75 3 _ 2,121,209 tillate or gasoline, is withdrawn from the sepa rator ‘I4 through a conduit 15 having a valve 16, but a portion of this condensate may be re hot reformed products then pass through the turned, if desired, through a branch line 11 hav~ oil, preferably of residual character and prefer ably containing unsaturated hydrocarbon or other reactive constituents, is delivered to the ing a valve"!!! and a pump 19 and returned to the upper portion of the fractionating tower 43 as re?ux. transfer line I06 to the reaction vessel I05. At the same time relatively heavy hydrocarbon The tower 43 is preferably provided at an in reaction vessel I05. Pressure tar withdrawn from the bottom of the still 42 may be delivered termediate point with a ‘trap-out tray 8I ‘so located as to make possible the‘ withdrawal of conduit 58 and a branch conduit I20 having a directly to the reaction vessel I05 through the ‘a side stream consisting of a heavy gasoline _ valve I2I. fraction suitable for reforming purposes. This side streamis withdrawn from the trap—out tray BI through a conduit 82 having a valved branch conduit 83 leading to: a lower point in the tower 43 and a branch conduit 84 having a valve 85 and a pump 80. Reduced crude withdrawn'from the separating compartment II of the fractionation tower 4 may be forced by the pump 39 through the conduit 38 and through a line I22 having valves I23 and I24 to the convection heating coil I03. - ' While in transit through the coil I03 the oil is Gases withdrawn from the separator 14 may be ' preferably heated to a mild cracking temperature of for example 800 to 850° F. under a pressure delivered to a fuel gas main or elsewhere through a pipe 80 having a valve 00, or may be diverted through a branch conduit 9i having a valve 92 and a gas pump 93. From the foregoing it will be apparent that I have provided a combined stripping and cracking system which may variously be operated to pro duce virgin gas, gasoline and residual‘ oil or reduced crude, as well as cracked gases, cracked gasoline, and pressure tar or residual oil result sufficient to permit the flow of the products through the transfer line I08 to the reaction vessel I05. By means of a conduit‘ I20 having a valve I21 and a pump I28, heavy hydrocarbon oil of suitable character for treatment in the coil I03 may be introduced through the conduit I22 25 to the coil I03. Residual oil withdrawn from the still 42 may also be delivered by means of the pump 59 to the conduit 58, a conduit I30 ' ing from the cracking operation, and, also if . having a valve I3I and a ‘conduit I22 to the coil desired a relatively heavy gasoline fraction of I03. The aforesaid stocks may be used either 30 such character as to be well adapted to be sub ljected to a reforming operation. As stated hereinabove, my invention contem plates, the selective treatment of a desired num ber of such products, together with the ultimate combination of such stocks or the products re sulting fromthe treatment of such stocks, under conditions favorable for polymerization and re action to produce valuable low-boiling petroleum 'oils, While it will be apparent that I may va riously accomplish the selective treatment of the stocks, in the present instance I have illustrated separately or in any desired combination. If desired, gasoline or' naphtha from the sen arator 24 or the trap-out tray ‘BI or both may be withdrawn from the conduit II'3 through a branch conduit I32 having a valve I33 and com municating with the conduit I 22, for the pur pose of commingling with and diluting the heavy hydrocarbon oil introduced into the coil I03 and for the further‘ purpose of making it possible to carry somewhat‘higher temperatures in the coil 40 I03 than would otherwise be possible. The oil while in transit through the coil I03 a preferred system which includes a furnace is, as aforesaid, heated to a mild cracking tem I00 provided with separate radiant heating coils perature to reduce the viscosity of the oil and to I M and I02 and convection heating coil I03, the products from which are delivered to a com mon reaction chamber I05, through transfer lines I00, I07 and I08, respectively. . effect a mild cracking with the result that the content of unsaturated hydrocarbon or other re active constituents in the oil may be increased and the products from the coil I03 are rendered more suitable for reaction and combination with other constituents under the conditions which obtain in the reaction vessel I05. In the instance illustrated in the drawing th radiant heating coil IOI is employed for the purpose of effecting the reformation or conver The coil I02 is preferably employed for the purpose of ,eifecting- a preliminary pyrolysis of gaseous hydrocarbons to promote the formation I] in delivered to the coil IOI through a conduit IIO > of gaseous unsaturated hydrocarbons, such as having a valve III and a pump II2, a conduit gaseous ole?ns, which are then delivered to the II3, and a conduit II4 having ‘a valve H5. The reaction vessel I05 through the transfer line ‘I01. heavy gasoline fraction withdrawn as a side Thus gas liberated in the separator 24 may be stream from the trap-out tray BI in the frac withdrawn through a conduit I40 having a valve 00 tionating tower 43 may also be delivered to the MI and a gas pump I42, bymeans of which the coil IIlI through a conduit 84 by means of the gas is forced through the coil I02. _ Communi pump 80, and the conduits II3 and-I I4. Naphtha cating with the conduit I40, I provide a gas sion. of constituents of gasoline or naphtha to constituents of increased anti-knock value. Virgin gasoline from the separator 24 may be or gasoline from an outside source may also be delivered to the coil I0! by means of a conduit IIii, wherein is located a pump Ill and a valve IIO. Any of the aforesaid gasolines or naphthas ‘may be employed alone or in any desired com bination. I ' While in transit through the coil IOI, the naphtha or gasoline is heated to a temperature of for example, from 850° F. to 1000" F’; or even higher, under'a suitable elevated pressure of, for example, from 200 to r750 pounds per square inch. Higher pressures of the order of 1000 75 1200 pounds may be usedwith advantage. The conduit I43 having a valve I44 which may re ceive hydrocarbon gas from_ an outside source through a conduit I45, wherein is located a gas pump I46. By means of the conduits I45, I43 and I40 any hydrocarbon gas suitable for pyroly sis to effect formation of unsaturated hydrocar bon constituents may be introduced into the coil I02. Thus I may employ natural gas or other ” O gas containing such constituents as ethane, pro pane, butane, pentane, ethylene, propylene and the like. While in transit through the coil I02, such gases are heated to a high cracking tem perature' of, for example, from 1100° to 1700” F., 2,121,209 under a suitably elevated pressure of, for ex ample, from 200 to 750 pounds per square inch or even higher, and the resultant pyrolized gases are then delivered through the transfer line I01 to the reaction vessel I05. Where the hydrocarbon gases to be delivered to I62 through a conduit I68 or by means of cooling effected in any other suitable manner, the va pors passing upward through the fractionating tower I62 are subjected to a fractional condensa tion to such an extent as to make possible the the reaction vessel I05 already contain su?i separation therefrom in liquid form of normally liquid products heavier than gasoline, that is to cient quantities of gaseous ole?ns or the like, they may be delivered directly to the reaction withdrawn from the trap-out tray I66 through 10 vessel I05 without-preliminary pyrolysis in the coil I02. Thus, cracked hydrocarbon gases from the gas separator 14 may be withdrawn through the conduit 9| and delivered by means of the gas pump 93 directly to the reaction vessel I05. 15 Furthermore, gases introduced into the system by means of the gas pump I46 may pass through the conduit I45 and a branch conduit I5I having a valve I52 directly into the reaction vessel I05. While various types of reaction vessels may be 20 employed, the reaction vessel I05 illustrated in the drawing represents the preferred type. This vessel comprises a more or less elongated vertical shell having an interiorly disposed annular ba?le I55 which separates the interior of the vessel 25 I05 into an annular compartment I56 and an inner compartment I51, which compartments say, an intermediate or gas oil fraction, which is a conduit I10 having a valved branch conduit 10 HI and a valved branch conduit I12 wherein is located a pump I13. This gas oil may be removed from the system through the conduit IN or, under the in?uence of the pump I13, may be‘ recycled, either through 15 a line I14 having valves I15 and I16 to the con duit 45 and thence into the coils 46, 41, and 48, or through a line I11 having valves I18 and I19 to the conduit I22 and thence into the coil I03. In the latter instance, the gas oil is employed 20 as a diluent for the relatively heavy oil passing through the coil I03. The gases and vapors remaining uncondensed at the top of the fractionating tower I62 are passed through ,a vapor line I80 to a condenser 25 I8I and through a condensate line I82 to a gas I56 and I51 intercommunicate in the upper por separator I83. The condensate, consisting of tion of the vessel I05. The various hydrocarbons naphtha or gasoline, is withdrawn from the sep to be reacted together in the vessel I05 are pref» arator I83 through a conduit I84 having a valve erably introduced into the lower portion of the I65. A portion of this condensate may, however, outer compartment I56 and pass upwardly be diverted from the conduit I84 through the re through the latter before passing downwardly ?ux line I68, wherein is located a valve I86 and through the inner compartment I51. The prod a re?ux pump I81, to be delivered to the top of ucts are then withdrawn through a conduit I58 the fractionating tower I62. 35 having a valve I59 for delivery to an evaporator The gases passing out of the ' separate I83 section I6I located within a fractionating tower may be removed from the system through a con I62. Conduits I58’ having valves I59’ and com duit I90 having a valve I9I, or may be diverted municating with the conduit I58 may also be in part through a branch line I92, having a valve provided for the purpose of limiting or prevent I93 and a gas pump I94 to the conduit I40 to be 40 ing accumulation of liquid products in the lower recycled through the coil I02 for further pyrol portion of the outer compartment I56. ysis. , The reaction vessel I05 is preferably main It will be apparent to those skilled in the art tained at a temperature effective to promote that, while I'have described hereinabove various polymerization of normally gaseous hydrocarbons preferred methods whereby a petroleum oil may 45 to normally liquid hydrocarbons and interaction be distilled, with the selective treatment of the between the various unsaturated hydrocarbon or‘ various products, and whereby petroleum prod other reactive constituents which may be pres ucts resulting from cracking of gases, reforming ent, for example, at a temperature of 150 to 900° of naphtha and the cracking of heavy oil may F. and under a pressure of from 200 to 750 be digested together under conditions favorable 50 pounds 'per square inch or even higher, for ex for the promotion of inter-reactions between re ample from 1000 to 2000 pounds per square inch. active constituents of such materials, my process As polymerization is favored by high pressure, it is not limited to such e'xempli?cation, but may is, of course, desirable to maintain as high a pres be varied in accordance with the character of sure in the reaction vessel I05 as possible andin the materials treated and the nature of the 55 practice this pressure is limited only by the results desired, within the scope of the claims pressures which it is possible to maintain in the hereinafter made. coils IIII, I02 and I03 from which the various I claim: products are delivered to the reaction vessel I05. 1. The process of treating a petroleum oil The products leaving the reaction vessel I 05, in passing through the conduit I58 to the evaporator which comprises introducing said oil into a dis section I6I are preferably considerably reduced tillation zone, receiving hot cracked vapors, sep— arately withdrawing residual oil and vapors from in pressure by means of the valve I59 for ex said zone, fractionating said vapors to separate ample, to a pressure of from 50 .to 200 pounds ly recover therefrom normally gaseous hydro per square inch, and upon reaching the rela carbons, a light gasoline fraction, a heavy gas 65 tively low-pressure evaporator section I6I, a sep~ oline fraction and a heavier gas-oil fraction, aration of liquid and vapors occurs, the liquid be independently subjecting said gas-oil fraction to ing withdrawn from the bottom of the evaporator a cracking temperature while in transit through section I6I through a conduit I63 having a valve a heating zone and discharging the resultant hot I64 while~the vapors pass upward around a plu products into said distillation zone to supply said rality of baf?es I65 and through a trap-out tray hot cracked vapors, subjecting said heavy gas I66 into'the upper portion of the fractionating oline fraction to conditions of temperature and tower I62 which is provided as shown with a plu pressure in a separate heating zone effective to rality of plates or trays I61. _ ‘ promote reformation of constituents of said By means of cooled re?ux oil introduced into heavy gasoline fraction to constituents of in 75 the upper portion of the fractionating tower creased anti-knock value, reacting the hot re 30 35 45 50 55 60 70 75 5 2,121,209 formed products and normally gaseous hydro carbons obtained as aforesaid with said residual oil under conditions effective to promote poly merization of gaseous hydrocarbons to normally liquid hydrocarbons, removing resultant prod ucts of said last-mentioned reaction‘and sepa rately fractionating them to recover said normal ly liquid hydrocarbons. .2. The process of treating. a petroleum oil 10 which comprises introducing said oil into a dis tillation zone receiving hot cracked vapors, sep-' arately withdrawing residual oil and vapors from said zone, fractionating said vapors to separately recover therefrom normally gaseous hydrocar 15 bons, a light gasoline fraction, a heavy gaso line fraction and a heavier gas-oil fraction, in dependently subjecting said gas-oil fraction to a cracking temperature while in transit through a heating zone and discharging the resultant hot products into said distillation zone to supply hot cracked vapors, combining said residual oil, normally gaseous hydrocarbons obtained as . aforesaid and said heavy gasoline fraction un der conditions. of temperature and pressure ef 25 fective to promote polymerization of ,gaseous hydrocarbons to normally liquid hydrocarbons, removing resultant products and separately frac tionating them to recover a gasoline fraction therefrom. , _ 3. The process of treating petroleum oil which comprises introducing said oil into a distillation zone receiving hot cracked vapors, separately withdrawing residual oil from said zone, frac tionating vapors obtained from said zone to sep 35 arately recover therefrom normally gaseous hy drocarbons, a gasoline fraction and a gas-oil 30 fraction,‘ independently subjecting said gas-oil fraction to a cracking temperature while in, transit through a heating zone ‘and discharging 40 the resultant hot products into said distillation zone to supply said hot cracked vapors, subject ing at least a part of said gasoline fraction to conditions of temperature and pressure in a sepa rate heating zone e?ective to promote reforma tion of constituents of said gasoline fraction to constituents .of increased anti-knock value, re acting the hot reformed products and normally gaseous hydrocarbons obtained as aforesaid with said residual oil under conditions effective to pro mote polymerization of gaseous hydrocarbons to 10 normally liquid hydrocarbons, removing result ant products from said last-mentioned reaction and separately fractionating them to recover said normally liquid hydrocarbons. 4. The process of treating a petroleum oil 15 which comprises introducing said oil into a dis tillation zone receiving hot cracked vapors, sep arately withdrawing residual oil and vapors from said zone, fractionating said vapors to separately recover therefrom normal gaseous hydrocarbons, 20 a gasoline fraction and a heavier gas-oil frac tion, independently subjecting said gas-oil frac tion to a cracking temperature while in transit through a heating zone and discharging the re sultant hot products intosaid distillation zone 25 to supply said hot cracked vapors, combining said residual oil, normally gaseous hydrocarbons obtained as aforesaid and at least a part of said gasoline fraction under conditions of tempera ture and pressure effective to promote polymeri 30 zation of gaseous hydrocarbons to normally liquid hydrocarbons, removing resultant products and separately fractionating them to recover a gaso line fraction therefrom. ‘ 5. A process in accordance with claim 4 where 35 in said residual oil is subjected to mild cracking prior to combining with said normally gaseous hydrocarbons and said gasoline fraction. WILLIAM F. MOORE.