US2220699A

US2220699A - Production of high antiknock gasoline

Info

Publication number: US2220699A
Application number: US166271A
Authority: US
Inventors: Charles H Angell
Original assignee: Universal Oil Products Co
Current assignee: Universal Oil Products Co
Priority date: 1937-09-29
Filing date: 1937-09-29
Publication date: 1940-11-05
Anticipated expiration: 1957-11-05

Description

N0". 5 1940. c. H. ANGELL PRODUCTION 0F HIGH ANTIKNOCK GASOLINE Filed sept, 29, 19s? .All

mm- Mh lll zjou

INVEN VOR CHARLES H. ANGELI.

ATTORNEY Patented Nov. .5, 1,940

UNITED STATES PRODUCTION F 4HIGH ANTIKNOCK GASOLINE Charles ll. Angell, Chicago, lll., assignor to Universal Oil Products Company, Chicago, lll., a corporation of Delaware Application September 29, 1937, Serial No. 166,271

4 Claims.

This is a continuation-impart of my co-pending application Serial No. 151,136, which was filed on June 30, 1937, and which, in turn, is a continuation-impart of my co-pending application Serial No.4 661,242 filed on March 17, 1933, now Patent No. 2,128,897.

The invention relates to an improved process for the pyrolytic conversion of light hydrocarbon oil distillates, such as gasoline, naphtha and the like, of inferior motor fuel characteristics, particularly with respect to antiknock value, for the purpose of producing therefrom high yields of good antiknock gasoline. This type of cracking operation is now generally known in the art as The process of the invention involves two cooperative but independently controlled reforming steps, the first of which is devoted to treatment of ,the gasoline or other light distillate charging stock, while the second reforming step is devoted to treatment of selected high-boiling gasoline fractions resulting from the first reforming operation; said high-boiling gasoline fractions being 3,', first separated from the lower` boiling gasoline fractions of the rst reforming operation, thence utilized as absorber oil for recovering readily polymerizable olefins such as propene and/or butenes from the process gases and then subjected to further treatment in the second mentioned reforming step in commingled state with the absorbed polymerizable gases; a full boiling range gasoline of high antiknock value being recovered from the lastmentioned reforming op- 3y, eration and including twice reformed gasoline and gasoline polymers resulting from the simultaneous treatment of said polymerizable gase and heavy gasoline fractions.'

The invention is particularly well adapted to the vtreatment of light distillates of unusually Yhigh paraiiinic nature which cannot be readily reformed to produce high yields of good antiknock gasoline in a single cracking operation.. Gasoline or naphtharecovered from Muskegon crude, 5 as well as some Pennsylvania distillates, exemplify this type of charging stock. On the other hand, as applied to the treatment of other light.

distillates of a less parafilnic nature, the process permits the production of gasoline of unusually 50 high antiknock characteristics. Each of these particular adaptabilities of the process herein provided results from the combination of two important features of the invention. One of these features resides in the provision for separating 5 the gasoline produced in the first reforming step reforming and will Abe hereinafter referred to for normally gaseous products of the process, y

whereby to recover from the latter readily polymerizable olenes gases such as propene and/or butenes, and supplying resulting enriched absorber oil to the second reforming step wherein the heavy gasoline'fractions and absorbed gases 15 -are subjected to simultaneous treatment under conditions which result in the production of a full boiling range gasoline of high antiknock value.

The invention also includes other advantageous features which, in the cooperative combinations y provided, are believed to involve invention over the prior art. These features will be explained in conjunction with the subsequent description of the accompanying drawing.- K

, The drawing, which is diagrammatic, illustrates one specific form of apparatus embodying the features of the invention and in which the process herein provided may be conducted. y

Referring to the drawing; the charging stock, which may be any desired light distillate (either 30 stright-run or cracked, or a mixture of straight- -run vand cracked products) containing at least a substantial quantity of gasoline or gasoline fractions of poor antiknock value, ls supplied through line I and valve 2 to pump3 by means 35 of which 'it is fed through line 4 and valve 5 to heating coil 6. 'I'he charging stock may, when desired, be preheated in any well knownmanner, not illustrated,v prior toits introduction into heating coil 6.

A furnace 1, of any suitable well known form, provides the required heat to the charging ,stock passing'through heating coil 6 to bring the same to the desired high cracking temperature, preferably at a substantial superatmospheric pressure, and preferably heating coil 6 and furnace 'I are of such Vwell known form that the oil is maintained at a high cracking temperature fora conl siderable predetermined time in the heating coil.

, The highly heated products are discharged from heating coil 6 through line 8 and are preferably cooled sufficiently as they pass through this line to prevent their excessive further cracking. 'I'he cooling is preferably accomplished at least in part by a substantial reduction in the pressure imposed on the stream of heated products as they pass through valve 9 in line 8 and additional cooling may be accomplished by the introduction of a suitable cooling oil into line 8, in the manner to be later described, and/or by indirect heat exchange between the relatively hot products and a suitable cooling medium. Means for accomplishing cooling by the latter method is not illustrated but is now Well known in the art.

The partially cooled products from heating coil 6 are introduced into chamber III wherein their vaporous components are separated from heavy non-vaporous products such as residual liquid and heavy polymers. The non-vaporous residue is withdrawn from the lower portion 'of chamber I0 through line II and valve I2 to cooling and storage or elsewhere, as desired, while the vaporous products are suppliedfrom chamber I0 .to fractionation in fractionator I3.

Chamber I0 and fractionator I3 are, in the particular case here illustrated, the lower and upper portions, respectively, of column I4, the two zones being separated by suitable partition or tray I5 through which vaporous products pass from chamber I0 to fractionator I3 and upon which reflux condensate formed in fractionator I3 may collect.

Fractionated vapors of the desired end-boiling point, which preferably include substantially all of the components of the vapors supplied to fractionator I3 boiling Within the range of gasoline and which may, when desired, also include somewhat higher boiling materials such as heavy f naphtha fractions. kerosene, kerosene distillate and the like, are removed, together with nor-- mally gaseous products of the reforming operation, from the upper portion of fractionator I3 and directed While still in hot vaporous state through .line I6 and valve I1 to further fractionation in fractionator I8.

The purpose of fractionator I8 is to condense and separate from the vaporous products supplied thereto substantially all of their components except the normally gaseous products and selected light gasoline fractions which are of satisfactory antiknock value. The condensed highg-boiling components, which include or consist of high-boiling gasoline fractions of unsatisfactory antiknock value, are removed from the lower portion of fractionator I8 through line I9 and valve 20 to pump 2I by means of which they are directed to further treatment, as will be later described. The normally gaseous products and desirable light gasoline fractions are directed from the upper portion of fractlonator I8 through line 22 and valve 23 to condensation and cooling in condenser 24, wherefrom the resulting distillate and uncondensed gases pass through line 25 and valve 28 to collection and separation in receiver 21. The uncondensed gases may be released from receiver 21 through line 28 and valve 29 to storage or elsewhere, as desired, or they may be supplied, all or in part, by well known means, not illustrated, to absorber 55. Distillate collected in receiver 21 is removed therefrom through line 30 and may be withdrawn, all or in part, from the system to storage or to any deied further treatment through valve 3| in line Ordinarily, however, the distillate collected in receiver 21 will contain a substantial quantity of dissolved normally gaseous products and the temperature and pressure conditions employed in receiver 21 may be so controlled that substantially all, or at least a major portion, 0f the readily polymerizable high-boiling gases such as propene and butenes, as well as the corresponding saturated compounds, remain dissolved in the distillate. In such cases, the distillate is preferably stabilized to reduce its vapor pressure to the desired degree by liberating dissolved gases therefrom and the gases released from he distillate by said stabilization are supplied to absorber 55. In other cases, temperature and pressure conditions may beso controlled in re' ceiver 21 that a substantial quantity or a major portion of the high-boiling gases are separated from the distillate in this zone, in which event gaseous products from receiver 21 are supplied, to absorber 55 and stabilization of the distillate may sometimes be dispensed with. The rst described mode of operation is the one most commonly employed and is the one here illustrated' and described in more detail in conjunction with the drawing.

The distillate to be stabilized, which consists of light gasoline fractions and dissolved gases, is directed from receiver 21 through line 32 and valve 33 to pump 34 Wherefrom it is fed through line 35 and valve 36 to stabilizer 40, preferably iirst passing through heat exchanger 31 wherein it is reheated suiiiciently to effect its appreciable vaporization by indirect heat exchange with a suitable heating medium from within the system or from an external source, the heated distillate being directed from heat exchanger 31 through line 38 and valve 39 into stabilizer 40.

Stabilizer 40 may comprise any desired type of stabilizing equipment and, in the case here illustratad, employs heating or reboiling means in the lower portion thereof, such as closed coil 4I through which a suitable heating medium is circulated, and also employs cooling means in the upper portionof the stabilizer, such as closed coil 42 through which a suitable cooling medium is circulated by means of

lines

43 and 45 controlled, respectively, by

valves

44 and 46. Any other well known means for establishing the desired equilibrium conditions may, however, be employed in stabilizer' 40, including means for introducing suitable cooling and/or heating media directly into the stabilizer. The stabilization in stabilizer 4I! is preferably controlled to liberate substantially all of the C4 and lighter dissolved gases and thereby leave a distillate of .unusually low vapor pressure.,

The stabilized distillate is withdrawn from the lower portion. of stabilizer 40 through line 41 and may be directed through valve 48 to cooling and storage or to any desired further treatment or, when desired, regulated quantities of this ma.-

terial may be utilized as a. heating medium in tion, the material employed as the absorption medium in absorber 55 comprises regulated quantities of the selected high-boiling fractions recovered, as previously described, from fractionator I8. This 'material is directed from pump 2| through line 56 and valve 51 to the upper por- `In accordance with the provisions of the inven` troduction into the absorber. Partial cooling of -a portion or all of the condensate from fracoil may be accomplished in cooler 62 through which all or a regulated portion of the condensate from line 56 is passed by means of lines 63 and 65 controlled, respectively, by valves 64 and 66, valve 61 in line 56 being either closed or only partially open, as desired.

'I'he relatively low-boiling gases, which remain unabsorbed in absorber 55, are released from the upper portion of this zone through line 68 and valve 69. The enriched absorber oil, which preferably contains substantially all of the readily.

polymerizable olens contained in the gaseous products supplied to absorber 55, is directed from the lower portion'of the latter zone through line 18 and Avalve 1I to pump 12 by means of which it is fed through line 13 and valve 14 to further cracking in heating coil 15.

-When all of the condensate from fractionator I8 is not required asabsorber oil that portion not supplied to absorber 55 may be supplied directly to heating coil 15 by diverting the same from line 56 through line 16 and valve 11 into line 13.

Heating coil 15 is located within 'a suitable furnace 18 and, preferably, heating coilV 'l5 and furnace 18, like heating coil 6 and furnace'l, are of such well known form that. the oil passing therethrough is maintained therein at a high cracking temperature fora substantial predetermined 'time. The conditionsoi temperature, pressure and time employed in heating coil 15 are regulated to effect a material improvement in the antiknock value of the high-boiling gasoline fractions vsupplied thereto from fractionator |8, as well as to effect conversion of any higher boiling fractions of the condensate supplied to this zone for the production of high yields of goed antiknock gasoline therefrom and also to eiect polymerization of the olefinic` gases recovered in absorber 55 and` supplied to heating coil15.

The hot conversion products are discharged from heating coil 15 through line 19' and are introduced through valve 88 in this line into separating chamber 8 I, preferably after being cooled suiciently as they pass through line 19 to prevent any excessive continued cracking. This cooling, as in the case of the heated products discharged from :heating coil 6, is preferably accomplished, at least in part, by 4a substantial reduction in the pressure imposed upon the stream of heated products as they pass through valve 88 in line -19 and any required additional cooling may be accomplished by the introduction of a suitable cooling oil into line 19, in the manner to be later described, and/or by indirect and gaseous products is accomplished in chamber 8|, the yresidual liquid being removed from the lower portion of this zone through line 82 and valve 83 to cooling and storage or elsewhere, as

desired, while the vaporous products are directed, 5

in the case here illustrated, from chamber 8| through a suitable partition or the like 84 into fractionator 85 which, in this particular case, comprises the upper portion of separating and fractionating column 82, the lower portion of 10 which comprises chamber 8|.

The components of the vaporous productssupplied to fractionator 85 which ,boil above the range of the desired gasoline product are condensed in this .zone as reflux condensate and, in 15 accordance with one specic mode of operation hereinprovided, a full boiling range gasoline having an end-point of the order of 350 to 400 F. or more, for example, is removed together with the normally gaseous products of this stage 20 of the system from the upper portion of fractionator 85 in vaporous state and directed through line 86 and valve 81 to condensation and cooling in rcondenser 88. The resultant distillate and uncondensed gases are directed through line 89 25 and valve 90 to collection and separation in receiver 9|. The uncondensed gases are released from the receiver through line 92 and valve 93 and max/when desired, be directed by well known means, not illustrated, to absorber 55. Distillate 30 collected in receiver 9| may be directed therefrom through line 94 and valve 95 to storage or to any desired further treatment or this material may be subjected to stabilization in stabilizer 40 or in a separate stabilizer, as desired.

When it is desired to stabilize the distillate collected in Areceiver 9|, it may be directed through line 96 and valve 91 to pump 98, by means of which it isV fed through line 99 and may be directed either to stabilizer 48 or to stabilizer 40 |88, preferably after being reheated and partially vaporized in any desired manner. Two means of reheating and partially vaporizing the distillate are illustrated in the drawing, one of which comprises heat exchanger 31, previously de- 45 scribed, to which the distillate may be supplied from pump 98 through line 99, line |0|, valve |62 and valve |83 and Wherefrom it may be di.- rected through line 38 and valve 39 into stabilizer 40. The other means illustrated comprises 50 heat exchanger I 84 to which the distillate is directed from pump 98 through line 99 and valve |05 passing through the heat exchanger in indirect heat exchange with all or a regulated portion of the condensate being supplied to heating 55 coil 15, the latter being diverted in regulated quantities from line 13 through line |86, valve |01, heat exchanger |04 and thence through lline |88 and valve |89 back into line 13, v-alve I|0 in v line 13 being 1 regulated'to suit requirements. le() When heat exchanger |84 is utilized, the reheated distillate is discharged from this zone through line II| and valve ||2 i'nto line 8| whereirom it may be supplied either 'through line I|3 vand valve |I4 to stabilizer 48 or through line ||5 and 65 valve I I6 to stabilizer |88..

In accordance with another specific modeof operation provided 4 by the invention,l fractionation may be so controlled in fractionator -85 as to .the light gasoline fractions are condensed and re- 75" covered in receiver 9| wherein they are separated from uncondensed gases and may be either removed from the system to storage or further treatment,v or supplied from receiver in the manners previously explained, to stabilization in either stabilizer 40 or stabilizer |00, as desired.

The last described method of operation is particularly desirable in case it is advantageous to separately treat the low-boiling and high-boiling gasoline components of the vaporous products supplied to fractionator 85, or in case either the low-boiling or the high-boiling gasoline fraction requires further treatment and the other fraction does not. 1n accordance with this method of operation, the high-boiling gasoline fractions are removed as a side-stream from a suitable intermediate point in fractionator 85, provision being made, in the case here illustrated, for removing the same from this zone throughlinel |1 andvalve ||8 wherefrom they may be directed to cooling and storage o'r to any desired further treatment or may be rst reboiled in any well known manner, not illustrated, to substantially free the same of dissolved gases and low-boiling components within the range of the desired overhead product from fractionator 85.

It is also within the scope of the invention, in-

stead of removing the high-boiling gasoline fractions as a side-stream from fractionator 85, to employ a separate secondary fractionator (similar to fractionator I8) to which the full boiling range gasoline and uncondensed gases may be directed in vaporous state from the upper portionof fractionator 85 and wherefrom low-boiling and ,high-boiling gasoline fractions of the desired gasoline product of this' stage of the system, is directed from the lower portion of this zone through line I I and valve |28 to pump |2| and is preferablyemployed as a heating and/0r cooling medium within the system. This material maybe utilized, all or in part, for example, as a means of preheating the gas-containing condensate supplied to heating coil ,15 by passing the same inindirect heat exchange therewith in heat exchanger |24, to which condensate from-fractionator 85 is directed by means of line |22 and valve |23 and through which all or a regulated portion of the gas containing condensate being supplied to coil is 'directed by means of line |25, valve |25, line |21 and valve |28, valve |29 in line 13 being regulated to suit requirements. The partially cooled redux condensate from fractionator 85 is directed from heat exchanger |24 through line |38 and valve |3| into line |32. When heat exchanger |24 is not utilized or when only a portion of the redux condensate from the lower portion of fractionator 85 is supplied to this zone. all or the remaining portion of this redux condensate may be supplied to line |32 through line` |33 and valve |34. Redux condensate may be removed from line |32 and from the system to cooling and storage or elsewhere, as desired, by

. means of line |35 and valve |35. Preferably,

however, a portion or all of this material is'utisides of valve'! and/or by directing the redux condensate in regulated quantities from line |32 through line |40 and through one or more branch lines |4| controlled by valves |42 into line 19 on either or both sides of valve 80.

The redux condensate formed in fractionator I3 may also be utilized in regulated quantities as a cooling medium and/or as a heating medium within the system. This material is withdrawn from the lower portion of fractionator |3 through line |44 and valve |45 to pump |48 wherefrom it is preferably directed, all or in part, through line |41 and valve |48 into and through closed coil |49 disposed within the lower portion of fractionator |8, wherein it serves as a heating medium for reboiling the condensate formed in this zone and wherefrom it is discharged through line |50. It may thence be directed in regulated quantities through line |32 into line 8, in the manner previously described, to serve as a cooling medium, and/or through line |40 into line 19, in the manner previously described, wherein it also serves as a cooling medium. Regulated quantities of the redux condensate formed in fractionator I3, may, when desired, be removed from the systeix to cooling and storage orelsewhere, as desired, by means of line |5| and valve v|52 communicating with line |41 or in any other well known manner, not illustrated. Stabilizer |88, when utilized, is preferably provided with suitable reboiling means in the lower portion thereof, such as. closed coil |55 through which any suitable heating medium may be circulated by means of lines |55 and |58 controlled, respectively, by valves |51 and |59. Stabilizer |00 is also preferably provided with means for cooling in the upper portion thereof, such as, for example, closed coil |50 through which any suitable cooling medium may be circulated by means of lines |8| and |53 controlled, respectively, by valves |52 and |54. The gases liberated from'the distillate in stabilizer |00 are removed from the upper portion of this zone through line |55 and valve |55 and may, when desired, be directed by well known means, not illustrated, to absorber 55. The stabilized distillate is withdrawn from the lower portion of stabilizer` |08 through'line |51 andsvalve |58 to cooling and storage or to any desired further treatment. The stabilization in stabilizer |00 is preferably controlled to leave a major portion, at least. of the C4 hydrocarbons in the stabilized distillate so that the latter will be of sudiciently high vapor pressure that, when blended with the stabilized distillate from stabilizer 48, there will be formed a blend having a vapor pressure (Reid) of the order of 8 to 12 lbs. per sq. in.

'Ihe preferred range ot operating conditionsv which may be employed to accomplish the objects of the invention in an apparatus such as illus-- trated and above described, may be approximately as follows:

Heating coil 5 preferably employs an outlet temperature within the range of 900 to 1050 F., or thereabouts, preferably with a superatmos-- pheric pressure at this point in the system of from 200 to 1,000 pounds, or thereabouts, per square inch. A

Separating chamber I8 is preferably operated ata substantially reduced pressure relative to that employed at the outlet of heating coil 5, the reduced pressure ranging, for example. from a pressure within 50 pounds, or thereabouts, of that employed at the outlet of heating coil 5 down to substantially atmospheric pressure.

@tionator I8.

Fractionator I3is preferably operated at substantially the same pressure as that employed in chamber I0, while fractionator I8 Amay be operated at.substantially the same or reduced pressure.

Any desired pressure ranging from 300 pounds, or more,- per square inch, superatmospheric.' down to substantially atmospheric pressure may be employed in stabilizer 40 and any desired pressure within this range may also be utilized in stabilizer I when the latter zone is employed. Substantially the same or somewhat lower pressure relative to that employed in stabilizer 40 may be utilized in absorber 55.

The temperature and pressure conditions employed at the outlet of' heating coil 15 may vary within substantially the same limits as those above mentioned in connection with heating coil 6. Ordinarily, however. the temperature and pressure conditions in the two heating coils are not identical, either coil being operated under more severe cracking conditions than the other and the relative conditions in the twocoils being regulated to suit requirements.

Chamber 8I is preferably operated atfa. substantially reduced pressure relative to that employed at the outlet of heating coil 15, which reduced pressure may range from 50 pounds, or thereabouts, below that employed at the outlet of heating coil 15 down to substantially atmospheric. t

Fractionator 85 is preferably operated at substantially the same pressure as that employed in chamber 8|. The condensing and collecting portions of the system may utilize pressures substantially the same or somewhat lower than that employed in the preceding fractionating zone.

Asan example of one specific operation of the process, conducted in accordance with the features of the invention in an apparatus such as illustrated and above described: The charging stock is a distillate from Muskegon, Michigan crude having a boiling rangeV of approximately 100 to 550 F. and of exceptionally poor antiknock value. This material is heated in coil 5 to an outlet temperature of approximately 950 F. at a superatmospheric.pressure of about 800 pounds per square inch, as measured at the outlet of the heating coil. The resultant conversion products are cooled to a temperature `of approximately 670 F., prior to their introduction into chamber I0, which is operated at a superatmospheric pressure of about 100 pounds per square inch. Substantially the same pressure is employed in fractionator I3 from which an overhead Vaporous stream having an end-boiling point of approximately 500 F. is supplied to frac- The latter zone is operated at a superatmospheric pressure of approximately 40 pounds per square inch and the overhead vaporous stream therefrom has an end-boiling point of approximately 300 F. Reflux condensate formed in fractionator I8 is reboiled by, indirect heat exchange with reux condensate from fractionator I3 as hereinafter described. A pressure approximately the same as that employed in fra'ctionator I8 and'a sufficiently low temperature is employed in receiver 21 so that at least the major portion .of the normally gaseous products of `this stage of the system boiling above ethane remaingdissolved in the distillate collected in this zone. In this particular operation, the distillate from receiver 21 is freed in stabilizer 40 of substantially all the butenesand lower boiling gases, the same being supplied to absorber 55.

while Ithe stabilized light gasoline fractions of low vapor pressure are recovered from stabilizer 40 'Ihe condensate formed in fractionator I8, which has an initial boiling point of approximately 275 F. and an end-boiling point of approximately 500 F. is cooled and supplied in' regulated quantities to absorber 55 wherein it absorbs substantially all of the propencs and butenes from the gaseous products supplied to this zone. The resulting enriched labsorber oil and the remainder of the condensate from fractionator I8, not utilized as absorber oil, are supplied to heating coil wherein the commingled materials are converted into high yields of good antiknock gasoline. A temperature of approximately 975 F. and a superatmospheric pressure of about 1000 pounds per square inch are employed at the outlet of heating coil 15, the re-v sulting heated products being cooled to a temperature of approximately 67'5"F., prior to their introduction into chamber 8I. The latter zone is operated at a superatmospheric'pressure of approximately 80 pounds per square inch and this pressure is substantially equalized in the succeeding fractionating condensing and collecting portions of the system. Reflux condensate formed inA fractionator 85 is cooled and returned in regulated quantities to line 19 as a cooling medium. The overhead vaporous product from fractionator 85 has an end-boiling point of approximately 420 F. and the temperature and pressure conditions in receiver 9| are so con- .trolled as to leave substantially all of the butane and some of the lower boiling fractions dissolved in the distillate. 'I'he distillate from receiver 9| is stabilized in stabilizer |00 to a. sumciently high vapor pressure that, vwhen commingled with the stabilized lowvapor pressure light gasoline fractions from stabilizer 40, the vapor pressure of the nal blended motor fuel product of the process is approximately 8 to 10 pounds per square inch. In lthis operation, no substantial quantity of readily polymerizable oleflns, such as propene and/or butenes, are contained in the gaseous` products released from receiver 21, absorber 55, receiver 0I and stabilizer |00'. These relatively lean gases are therefore released from the system to storage or elsewhere, as desired.

The operation above described will yield per and fractionating the resultant vapors and gases d to condense and separate fractions thereof heavier than, gasoline, further fractionating the uncondensed gasoline-containing vapors and gases to form an intermediate condensate containing heavy gasoline fractions vof inferior anti-knock value, a light gasoline condensate of satisfactory anti-knock value and a normally gaseous fraction, combining polymerizable components of said gaseous fraction with said intermediate condensate, subjecting the resultant mixture in a second conversion zone to independently controlled conditions of temperature and pressure adequate to reform the intermediate condensate and polymerize normally gaseous olefins, and recovering from the resultant products a distillate boiling within the gasoline range.

2. The process as dened in claim 1 further characterized in that said polymerizable components are combined with said intermediate condensate by scrubbing said gaseous fraction with at least a portion of the' intermediate condensate.

3. A conversion process which comprises sub jecting hydrocarbon oil to cracking conditions of temperature and pressure in a conversion zone and fractionating the resultant vapors and gases to condense and separate fractions thereof heavier than gasoline, further fractionatin'g the uncondensed gasoline vapors and gases to separate therefrom a heavy gasoline condensate of inferior anti-knock value, subjecting the remaining light gasoline vapors and gases to final condensation 'under suiiicient pressure to liquify a substantial portion of the gases with the light gasoline va- .pors, removing from the resultant lnal condensate, by stabilization thereof, substantially all of the C4 and lighter hydrocarbons contained therein, thereby forming a stabilized distillate of lower vapor pressure than commercial motor fuel, combining normally gaseousy hydrocarbons thus liberated from the final condensate with at least a portion of said heavy condensate, subjecting the resultant mixture in a second conversion zone to independently' controlled conditions of temperature and pressure adequate to reform the heavy condensate and polymerize normally gaseous olens, separating from the resultant products a gasoline boiling condensate containing a substantial amount of C4 hydrocarbons, and blending the last-named condensate with 'said stabilized distillate to form a. commercial motor fuel.

4. The process as defined in claim 3 further characterized in that said hydrocarbon oil is a light parailinic distillate of the character of gasoline and naphtha.

- CHARLES H. ANGELL.