US2184069A - Treatment of hydrocarbon oils - Google Patents

Description

Dec. 19, 192.9.

C. H. ANGELL TREATMENT OF HYDROCARBON OILS Filed May 31, 193s DISTILLING AND FRACTIONATING COLUMN STABILIZ ER ACCUMULATOR ABSORBER- Ill INVENTOR CHARLES H. ANGELL ACC LA CONDENSER FURNACE 22 ATTORNEY Patented Dec. 19, 1939 [TED STATES PATENT OFFICE TREATMENT OF HYDROCARBON OILS Application May 31, 1938, Serial No. 210,894

20 Claims.

This is, in part, a continuation of my co-pending applications Serial No. 661,242, filed March 17, 1933, and Serial No. 171,871, filed October 30, 1937.

The invention embodies a novel and advantageous combination of distilling, cracking, stabilization and absorption steps which are interdependent and cooperate to produce high yields of good antiknock gasoline of the desired vapor pressure. Readily polymerizable normally gaseous olefins produced in the cracking operation and which are ordinarily left dissolved in the gasoline to give it the desired vapor pressure are replaced by essentially paraifinic gases contained in the charging stock and recovered from the distilling step. The liberated gases or selected highboiling fractions thereof may be recovered as a separate product of the process which is suitable for catalytic polymerization, to produce additional yields of high antiknock gasoline, or they may be absorbed in the distillate from the distilling operation which is subsequently supplied to the cracking or reforming step of the system, wherein they undergo conversion in commingled state with said distillate under conditions which result in the production of higher yields of gasoline and/or gasoline of higher antiknock value.

While the invention is particularly advantageous as applied to the treatment of crude petroleum, any type of chargingstock which contains gasoline or gasoline fractions of unsatisfactory antiknock value and substantial quantities of essentially paramnic gases may be utilized. Such charging stocks often contain some low-boiling gasoline fractions of sufiicientl ood antiknock value that they may be advantageously included with gasoline produced within the system by pyrolytic conversion or reforming to form the final gasoline product of the process. Such light gasoline fractions and normally gaseous components of the charging stock are separated in the distillation step from its higher boiling components and commingled under suitable conditions with the gasoline resulting from said conversion, after the latter has been stabilized to a low vapor pressure by liberating therefrom substantial quantities of dissolved gases which contain a high percentage of readily polymerizable olefins, such as propene and butenes. Substantial quantities of highboiling parafiinic gases are thus dissolved or absorbed in the gasoline resulting from commingling the light products of the distillation step and the low vapor pressure cracked gasoline to replace the olefin-containing gases previously liberated therefrom by said stabilization and this commingled gasoline product is preferably stabilized in a zone separate from the first mentioned stabilization step to produce a final gasoline product of the desired vapor pressure.

When it is desired to subject the total gasoline components of the charging stock to reforming treatment for the purpose of improving their antiknock value, only normally gaseous components of the charging stock are commingled with the low vapor pressure distillate resulting from the first mentioned stabilization step.

The olefinic-containing gases liberated in the first mentioned stabilization step may be recovered or directly supplied, all or in part, to a well known catalytic polymerization process or they I may be subjected to condensation and the resulting condensate supplied, all or in part, to catalytic polymerization or to the pyrolytic conversion step of the system for treatment in commingled state with the low-boiling fractions of the charging stock supplied to this zone. Preferably, however, when it is desired to supply olefin-containing gases to the conversion step, gases liberated from the first mentioned stabilization step are intimately'contacted with absorber oil, which comprises regulated quantities of said lowboiling fractions of the charging stock which are to be converted, and the resulting enriched absorber oil is supplied to the conversion step.

As previously indicated, the selected low-boiling fractions of the charging stock to be subjected to cracking or reforming treatment may include or substantially exclude low-boiling gasoline fractions and, in either case, this cracking stock may include, when desired, somewhat higher boiling materials such as, for example, heavy naphtha fractions, kerosene or kerosene distillate and the like which can be advantageously treated, under reforming conditions of high cracking temperature and superatmospheric pressure, to produce substantial yields of good antiknock gasoline.

One specific embodiment of the invention comprises heating a charging stock comprising gasoline and essentially paraffinic gases to distillation temperature and separating therefrom, by fractional distillation, a light vaporous stream consisting essentially of parafiinic gases and selected light gasoline fractions and a condensate comprising heavier gasoline fractions of unsatisfactory antiknock value,'reforming said heavier gasoline fractions under controlled time, temperature and pressure conditions regulated to produce therefrom high yields of good antiknock gasoline and substantial quantities of olefinic gases, recovering from the reforming step, by fractionation of the vaporous products thereof and condensation of the fractionated vapors, a distillate comprising said good antiknock gasoline and containing, as dissolved gases, at least a major portion of the desired readily polymerizable olefins produced in the reforming step, stabilizing said distillate to a lower vapor pres sure than that of the desired final gasoline product by liberating therefrom regulated quantities of said dissolved gases, intimately contacting gases thus liberated from the distillate with regulated quantities of said higher boiling gasoline .fractions from the distilling step, whereby to absorb in the latter substantial quantities of said readily polymerizable olefinic gases, supplyingthe resulting enriched absorber oil to the reforming step, cooling and commingling the low vapor pressure distillate resulting from said stabilization and said light vaporous stream from the distilling step to condense the light gasoline fractions of the vaporous stream and absorb therein and in said stabilized distillate substantial quantities of said paraffinic gases and liberating from the gas-containing distillate resulting from said cooling and commingling regulated quantities of the absorbed gases to produce said final gasoline product of the desired vapor pressure.

Numerous modifications of the specific embodiment of the invention above described, and several alternative modes of operation, which have been previously mentioned and are not to be considered equivalent, are within the broad scope of the invention. Its primary object is to provide a cooperative combination of distilling and cracking steps which will result in the production of high yields of good antiknock gasolineof the desired vapor pressure, said vapor pressure resulting to a large extent from inclusion in the final gasoline product of paraflinc gases resulting from the topping operation, and the operation further resulting in recovery, from the cracked products, of substantial quantities of readily polymerizable normally gaseous olefins suitable for polymerization treatment within or external to the system, to produce additional quantities of high antiknock gasoline.

The accompanying drawing diagrammatically illustrates one specific form of apparatus in which variouaembodlments of the process of the invention may be successfully conducted.

Referring to the drawing, the charging stock, which in this particular case is a crude oil of relatively wide boiling range, is supplied in heated state through line I and valve 2 to distilling and fractionating column 3. Heating of the charging stock to distillation temperature may be accomplished in any well known manner, not illustrated, and, when desired, heat for this purpose may be recovered from within the system.

In the case here illustrated, the crude is separated in column 3 into three selected fractions, one of which is an overhead vaporous stream consisting primarily of light gasoline fractions of satisfactory antiknock value and gaseous components of the charging stock. This overhead stream is directed from column 3 through line 4 and valve 5 to condenser 6, the" function of which will be later described.

An intermediate fraction comprising gasoline of unsatisfactory antiknock value and which may, when desired, include somewhat higher boiling materials such as heavy naphtha fractions, kerosene, kerosene distillate and the like is removed as a side stream from column 3 and directed through line 1 and valve 8 to stripper 9, wherein it is substantially freed of dissolved gases and desirable low-boiling fractions by reboiling in this zone. Reboiling is accomplished, in the case here illustrated, by passing a suitable heating medium through closed coil in in the lower portion of stripper 9. The evolved vapors and gases may be returned, as shown, from stripper 9 through line H and valve 12 to fractionator 3, or they may, when desired, be supplied from stripper 9 to condenser 6, by well known means not illustrated. The reboiled condensate is directed from the lower portion of stripper 9 through line l3. and valve M to pump l5 by means of which it is fed through line l6, and, when desired, may be directed therefrom, all or in part, through line H and valve l8 to heating coil 19, the function of which will be later described, or the reboiled distillate may, when desired, be cooled and utilized in regulated quantities, as will be later described, for absorbing gaseous products of the conversion step of the system and thence supplied, in the manner later described, to heating coil I9. I

The remaining higher boiling components of the crude are removed as bottoms from the lower portion of column 3 through line'20 and valve 2| wherefrom they may be directed, by well known means not illustrated, to storage, cracking treatment or elsewhere, as desired. It will, of course, be understood that theparticular separation of the charging stock effected in the distilling step may be varied, depending upon the specific charging stock employed and the desired products, and that any desired separation may be accomplished within the scope of the invention so long as a relatively light distillate, suitable for conversion to produce high yields of good antiknock gasoline, and predominantly paraflinic gases are separately recovered from the charging stock.

Heating coil I9 is disposed within a furnace 22 whereby the materials supplied to this zone are heated preferably to a relatively high cracking temperature at substantial superatmospheric pressure. The conditions of temperature, pressure and time employed in this step of the system are regulated to materially improve the antiknock value of the gasoline fractions supplied thereto without excessively altering their boiling range and to produce substantial yields of good antiknock gasoline from any higher boiling distillate fractions supplied thereto. When olefinic gases are supplied to coil IS, in the manner later described, substantial quantities thereof are also converted, under the conditions maintained in this zone, into appreciable additional yields of good antiknock gasoline. This conversion of the olefinic gases is probably due to some extent to their polymerization under the temperature and pressure conditions employed-in coil l9, but other reactions, such as alkylatlon, for example, are probably also involved. It is also considered quite probable that there are secondary reactions between the various primary conversion products formed in coil l9, although the exact nature of this reaction and the reactants involved cannot be definitely stated at the present time.

The highly heated products formed in coil 19 are discharged therefrom through line 23 and these materials are discharged into separating chamber 25, preferably after they have been cooled 'sufliciently to prevent excessive continued cracking and undesirable secondary reactions.

This cooling is preferably accomplished, in part, by materially reducing the pressure imposed upon the stream of heated products as they pass through valve 24 in line 23 and additional cooling, when required, may be accomplished in any well known manner such as, for example, by indirect heat exchange between the conversion products and a suitable cooling medium or by directly commingling regulated quantities of a suitable cooling oil with the stream of conversion products. When desired, heat for the distilling operation may be recovered at this point in the system by passing all or regulated quantities of the charging stock in indirect heat exchange with the stream of relatively hot conversion products discharged from coil I9. However, the well known provisions whereby cooling of the products .dis-

charged from coil US by indirect heat exchange are, for the sake of simplicity, omitted from the drawing. Provision is made, in the case here illustrated, for supplying any suitable cooling oil to line 23 by means of lines 21 controlled by valve 29, the cooling oil being introduced on either or both sides of pressure reducing valve 24.

Heavy liquid conversion products are separated from vaporous conversion products in chamber 25 and the'residual liquid is removed from the lower portion of this zone to cooling and storage or elsewhere, as desired, through line 29 and valve 30.

The vaporous conversion products from chamber 25 enter fractionator 3| wherein their components boiling above the range of the desired gasoline product are condensed as reflux condensate. The reflux condensate is removed from the lower portion of the fractionator through line 32 and valve 33 and may be directed to cooling and storage, to further conversion in heating coil l9 or in a separate cracking coil or supplied elsewhere, as desired.

Fractionated vapors of the desired end-boiling point, comprising gasoline of the desired end boiling point produced by conversion in coil [9 and normally gaseous products of the conversion step, are directed from the upper portion of fractionator 3! through line 34 and valve 35 to condenser 36 wherein they are cooled sufliciently to condense substantially all of their normally liquid fractions and to retain substantial quantities of dissolved gases in the resulting distillate. This distillate is passed together with uncondensed and undissolved gases from condenser 36 through line 37 and valve 39 to receiver 39, wherein the uncondensed and undissolved gases are separated from the gas-containing distillate.

The temperature and pressure conditions employed in condenser 36 and receiver 39 are preferably such that at least a major portion of the desired readily polymerizable olefinic gases (such as propene and/or butenes) contained in the overhead vaporous stream from iractionator 3| are retained in the distillate collected in receiver- 39. .The uncondensed and undissolved gases removed from receiver 39 preferably comprise a major portion of the gases produced by conversion which have two and less carbon atoms to the molecule but will ordinarily also contain a minor portion of the heavier gases. This material is directed through line 44 and may be discharged through valve 4| in this line to storage or elsewhere, as desired, or it may be directed, all or in part, from line 49 through line 42, valve 43 and line 44 to condenser 6 or, from line 42, through line 45, valve 46 and line 41 to absorber 43.

The distillate collected in receiver 39 is stabilized to reduce its vapor pressure to a value substantially below that of the final gasoline product by liberating therefrom regulated quantities of the dissolved gases. To accomplish this, in the particular case here illustrated, distillate is directed from receiver 39 through line 49 and valve 59 to pump 5| wherefrom it is fed through line 52, heat exchanger 53, line 54 and valve 55 to stabilizer 56. Suflicient heat is imparted to the distillate in heat exchanger 53 to efiect appreciable vaporization thereof and, in accordance with conventional practice, reboiling may be accomplished in stabilizer 56 or in a reboiler external to the stabilizing column. In the case here illustrated, closed coil 51, through which any suitable heating medium may be passed for reboiling the unvaporized distillate in stabilizer 56, is provided in the lower portion of this zone. Reboiling may, of course, be accomplished in any other well known manner, not illustrated. Provision is also made for controlling stabilization by cooling in the upper portion of column 56, this being accomplished, in the case here illustrated, by passing any suitable cooling medium through closed coil 58, provided therein. Any other conventional methodoicooling may, of course, be substituted.

The low vapor pressure stabilized distillate resuiting from the liberation of gases in stabilizer ..be ing through line 62, valve 63, heat exchanger 53, line 44 and valve 64 to condenser 6. It is not essential to cool the stabilized distillate prior to its introduction into condenser 6, since all of the required cooling may be accomplished in the latter zone. The specific manner of cooling the stabilized distillate in heat exchanger 53 con forms with conventional practice.

The mixture of vapors, gases and stabilized distillate supplied to condenser 6, in the manner previously described, is cooled sufliciently in this zone to efiect condensation of substantially all of the normally liquid gasoline fractions of the mixture and to effect the absorption of substantial quantities of the gases supplied to this zone from column 3 in the distillate condensed in and supplied to condenser 6. At least a portion of the heat of absorption is also extracted in condenser 6, so that the distillate supplied therefrom through line 65 and valve 61 to accumulator 68 will retain a relatively large quantity of dissolved gases and particularly high-boiling normally gaseous fractions of the overhead stream from column 3. The 'uncondensed and unabsorbed gases, which consist predominantly of relatively light fractions, are discharged from accumulator 68 through line 69 and valve 10 to storage or elsewhere, as desired.

-The quantity of gases dissolved in the distillate collected in accumulator 68 will normally be in excess of that required to produce the desired vapor pressure in the flnal gasoline product and this distillate is, therefore, preferably stabilized to the desired vapor pressure in a stabilizing zone separate from stabilizer 56 To accomplish this, in the case here illustrate d, distillate is directed from accoumulator 63 through line II and valve 12 to pump 13 wherefrom it is fed through line I4, valve 15, heat exchanger 16, line 11 and valve 19 into stabilizer I9. The function of heat exchanger I6 is to reheat and partially vaporize the distillate supplied to stabilizer 19 and cool the stabilized gasoline removed from this zone. Other well known means of accomplishing either or both of these steps may, of course, be employed within the scope of the invention.

Stabilizer I8 is a conventional stabilizing column employing suitable means, such as closed coil 88 in the lower portion thereof, for reboiling and suitable means, such as, for example, closed coil 8I in the upper portion of this zone, for cooling, a suitable heating medium being passed through coil 88 and a suitable cooling medium through coil 8|. The gases liberated from the distillate in stabilizer I9 are released from the upper portion of this zone through line 82 and valve 83 to storage or elsewhere as desired. The distillate which has been stabilized in column I9 to the desired vapor pressure is removed as the final gasoline product from the lower portion of this zone and, in the particular case here illustrated, is directed through line 84 and valve 85 to and through heat exchanger 18, wherein it passes in indirect heat exchange with the distillate from accumulator 88 and wherefrom it is discharged through line 88 and valve 81 to further cooling and storage or to any desired further treatment. This stabilized product I is of higher vapor pressure than the distillate resulting from separate stabilization in stabilizer 56.

The gases liberated in stabilizer 58 from the distillate supplied to this zone may comprise either an intermediate or a final product of the process and, depending upon the specific mode of operation desired, may be handled in several different manners. In accordance with one embodiment of the invention, the gases released from the upper portion of stabilizer 56 are directed through line 88 and valve 89 to condenser 98 wherein they are, cooled sufllciently to effect substantial condensation thereof and wherefrom the resulting condensate and uncondensed gases are directed through line 9I and valve 92 to accumulator 93. Uncondensed gases may be removed from accumulator 93 through line 94 and valve 95 to storage or elsewhere, as desired, or they may be supplied by well knownmeans, not illustrated, to condenser 6. The condensate collected in accumulator 93 will contain a high proportion of readily polymerizable normally gaseous olefins such as. propene and/or butenes and is highly suitable as polymerization stock for a well known catalytic polymerization process operated to produce high antiknock gasoline from the heavy olefins. It is also suitable stock for treatment in coil I9, to produce appreciable quantities of high antiknock gasoline in the manner previously described. It is directed, in the case here illustrated, from accumulator 93 through line 98 and valve 91 to pump 98 wherefrom it is fed through line 99 and may be discharged from the system to storage or to polymerization in a separate system through line I88 and valve I8I or it may be supplied, all or in part, through valve I82 in line 99 to heating coil I9.

Another manner of handling the gases from stabilizer 58 and/or the gases previously separated from the distillate in receiver 39 involves the absorption therefrom of high-boiling components, comprising substantial quantities of read' ily polymerizable olefins such as propene and/or butenes, in absorber 48. Provision is made for supplying gases from stabilizer 56 to absorber 48 through line 41 and valve I83, while gases from receiver 39 may be supplied to this zone, when desired, either alone or together with gasesfrom stabilizer 56, in the manner previously described.

Any desired relatively light distillate capable of absorbing the desired high-boiling components of the gases supplied to absorb'er 48 and suitable for cracking treatment in heating coil I9 may be employed within the scope of, the invention.

When absorber oil from an external source isand due to the fact that its use in this manner provides a simple and efllcient method of supplying polymerizable gases to coil I9.

Provision is made, in the case here illustrated, for directing regulated quantities of the light distillate supplied from column 9 to pump I5 and line I6 through line I88 and valve I81 to cooler I88 wherein its temperature is reduced to the desired degree and thence through line I88 and valve I89 to the upper portion of absorber 48, wherein it comes in intimate countercurrent contact with the gases supplied to this zone as previously described, and absorbs desirable. high-boiling components thereof. The gases remaining unabsorbed in absorber 48 will consist predominantly of relatively light gases and are released from the upper portion of this zone through line H8 and valve II I to storage or elsewhere, as desired. The enriched absorber oil which will contain a substantial quantity of di solved heavy gases rich in readily polymerizable oleflns such as propene and butenes, is directed from the lower portion of absorber 48 through line II2 and valve II3 to pump II4 wherefrom it is supplied through line II5, valve H8 and line 99 to conversion, in the manner previously described, in heating coil I9.

It will, of course, be understood that the invention i not limited to the use of the specific form of apparatus illustrated in the drawing, but that the latter simply represents one specific means of successfully accomplishing the desired process steps. As an example of one alternative, not illu trated, an absorber similar to absorber 48, for example, may be substituted for condenser 6, the low vapor pressure stabilized distillate from stabilizer 56 being cooled and supplied as absorber oil to the upper portion of this zone, while the-overhead vaporous stream from column 3 is supplied, with or without prior cooling, to the lower portion of the absorber or, when desired, distillate may be first condensed and separated from this overhead vaporous stream and the uncondensed gases supplied to an absorber in which stabilized distillate from stabilizer 56 is utilized as absorber oil. However, the use of condenser 8 in the manner illustrated, provides a simple and efiicient means of accomplishing the desired results and this is the preferred mode of operation.

In an apparatus, such'as illustrated and above described, the preferred range of operating conditions which may be employed to produce the desired results, may be exemplified as follows: Any desired pressure ranging from substantially atmospheric to a superatmospheric pressure of several hundred pounds per square inch may be 4 employed in the distilling and fractionating column. The temperature utilized in this zone will depend upon the characteristics of the charging stock employed and, with a wide boiling range crude, for example, may range from 400 to 700 F., or thereabouts. Higher temperatures are, of course, necessary in column 3 when this zone is operated at substantial superatmospheric pressure, as compared with those required to give similar results at lower pressure. With a substantially atmospheric or low superatmospheric pressure up to 35 pounds, or thereabouts, per square inch in column 3, condenser '6 and accumulator 68, the condenser is preferably operated to give an outlet temperature from this zone in the neighborhood of 100 F., or thereabouts. The temperature employed in stripper 9 is preferably sumcient to remove substantially all gases and good antiknock light gasoline fractions from the material supplied thereto and, when desired, stripping may be assisted in column 9 by utilizing a lower pressure in this zone than that employed in column 3, when the latter is operated at superatmospheric pressure. The temperature employed in stripper 9 may range, for example, from 150 to 350 F., or thereabouts, depending upon the end boiling point of the good antiknock light gasoline components of the charging stock. The temperature employed at the outlet of coil 09 is preferably of the order of 925 to 1100 F. with a superatmospheric pressure at this point in the system of from 200 to 1000 pounds, or

thereabouts, per square inch. The heated products discharged from this zone are preferably cooled to a temperature of the order of 600 to 750 F. prior to their introduction into chamber 25 and/ or within the latter zone. A superatmospheric pressure substantially lower than that employed at the outlet of coil I9 is preferably utilized in chamber 25 and fractionator 3| and may range, for example, from 100 to 200 pounds, or thereabouts, per square inch. Preferably, condenser 36 is operated to cool the products discharged therefrom to a temperature of the order of 90 to 110 F., or thereabouts, and receiver 39 is preferably operated at substantially the same pressure as that employed in fractionator 3i.

Stabilizer 56 is preferably operated at a substantial superatmospheric pressure of the order of 200 to 300 pounds, or thereabouts, per square inch with a bottom temperature of the order of 400 F, for example, when the superatmospheric pressure employed in this zone is in the neighborhood of 250 pounds per square inch and witha top temperature, under these conditions, of approximately 130-145 F. Condenser 90 and accumulator 93 are preferably operated at a superatmospheric pressure substantially the same as that employed in stabilizer 56 and at a temperature of the order of ,70 to 90 F. or less. When absorber 38 is employed, it is preferably operated at a superatmospheric pressure of the order of 70 to 150 pounds or more. Stabilizer i9 is preferably operated at a superatmospheric pressure of from 100 to 150 pounds per square inch, or more, with a bottom temperature in this zone of the order of 300 to 325 F. and a top temperature of approximately 120 F., or less. In each of the various steps, the temperatures employed are, of course, closely allied with the pressure employed and either may be varied to give substantially the same or similar results when the other is correspondingly varied.

- As an example of one specific operation of the process, as conducted in an apparatus such as illustrated and above described, the charging stock is a light mixed base crude containing approximately 15% of satisfactory antiknock gasoline fractions boiling up to approximately 250 F. and containing more than 40% of materialsboiling up to 437 F. This charging stock is heated to a temperature of approximately 650 F. and fractionated at substantially atmospheric pressure. Gases and light vapors having an endboiling point of approximately 250 F. are removed as the overhead vaporous product from the fractional distilling step, cooled in comminged state with the low vapor pressure reformed gasoline from the stabilizer of the reforming system to a temperature of about 100 F., the resulting distillate separated from the uncondensed and undissolved gases and supplied to a separate stabilizer wherein its vapor pressure is reduced to approximately pounds per square inch as determined by the Reid method. This stabilizer is operated with a bottom temperature of approximately 315 F. and a top temperature of approximately 120 F.

A light side stream having an end-boiling point of approximately 540 F. is removed from the distilling and fractionating column to a stripping column wherein it is reboiled at a temperature of approximately 275 F., the evolved vapors and gases being returned to the distilling column and the reboiled distillate supplied to the reforming coil of the system wherein it is heated to an outlet cracking temperature of approximately 980 F. A superatmospheric pressure of about 800 pounds per square inch is employed at the outlet of the reforming coil and the products discharged therefrom are cooled to a temperature of about 670: F. and introduced into a separate chamber operated at a superatmospheric pressure of about 125 pounds per square inch, wherein, their vaporous components are separated'from residual liquid. The vapors are fractionated at a superatmospheric pressure of about 125 pounds per square inch to condense their components boiling above the range of approximately 400 F. The fractionated vapors and gases are subjected to condensation at a temperature of about 100 F. The resulting distillate, containing dissolved gases, is separated from the uncondensed and undissolved gases and supplied to the first mentioned stabilizer which is operated at a superatmospheric pressure of about 250 pounds per square inch. A bottom temperature of approximately 400 F. and a top temperature of approximately 135 F. is employed in this zone. The resulting stabilized, reformed gasoline, which has a vapor pressure of approximately 4 pounds per square inch, is supplied to the aforementioned condenser to which overhead point gasoline. The final blended gasoline prod-' uct has an octane number of approximately 68 and a Reid vapor pressure of approximately 10 pounds per square inch. In addition, approximately 7.6 gallons of liquified. gases, highly suitable as polymerization stock, are produced per barrel of distillate supplied to the reforming coil.

As an example of another specific operation of the process, the charging stock and operating conditions are substantially the same as those above described, except that the .gaseous prod ucts from the stabilizer to which the reformed distillate is supplied are directed to an absorber to which regulated quantities of the reboiled sidestream from the stripping column of the distilling step are supplied, after cooling, as absorber oil and the resulting enriched absorber oil supplied to the reforming coil.

On the same basis as given in the first example, the last described operation will produce approximately 78% of 400 F. end-point gasoline having an octane number of approximately 72 when substantially all of the gases from the stabilizer of the reforming system are supplied to the absorber and no catalytic polymerization stock is recovered.

LI claim as my invention:

1. A process of converting hydrocarbons which comprises, distilling an oil containing poor antiknock gasoline and essentially parafiinic gases to recover therefrom as separate fractions a distillate, comprising said poor antiknock gasoline, and lighter fractions comprising at least a major portion of said parafiinic gases, subjecting said distillate to conversion conditions regulated to efiect the production therefrom of high yields of good antiknock gasoline and substantial quantitles of readily polymerizable normally gaseous olefins, recovering said good antiknock gasoline from the resulting conversion products in the form of a distillate substantially free of dissolved normally gaseous olefins, adding to the last named distillate substantial quantities of the heavy parafiinic gases resulting from the .distillation step to form a gasoline product of materially increased vapor pressure, and separately recovering from said conversion products a mixture of normally gaseous hydrocarbons containing a high concentration of readily polymerizable olefins.

2. A process such as defined in claim lfwherein at least a portion of the readily polymerizable olefinic components of said conversion products is returned to said conversion step and therein further converted in commingled state withthe first named distillate to produce additional yields of good antiknock gasoline.

3. A process of converting hydrocarbons which comprises, distilling an oil containing poor antiknock gasoline and essentially parafiinic gases to recover therefrom as separate fractions a distillate, comprising said poor antiknock, gasoline, and lighter fractions comprising at least a major portion of said paraflinic gases, subjecting said distillate to conversion conditions regulated to efiect the production therefrom of high yields of good antiknock gasoline and substantial quantitles of readily polymerizable normally gaseous olefins, recovering said good antiknock gasoline from the resulting conversion products in the form of a distillate substantially free of dissolved normally gaseous olefins, adding to the last named distillate substantial quantities of the heavy parafiinic gases resulting from the distillation step to form a gasoline product of materially increased' vapor pressure, contacting normally gaseous components of said conversion products with regulated quantities of the first named distillate to absorb in the latter substantial quantities of readily polymerizable oleflnic gases, and supplying the resulting gas-containing distillate to said conversion step.

4. A process of converting hydrocarbons which comprises, distilling an oil containing poor antiknock gasoline and essentially parafilnic gases to recover therefrom as separate fractions a distillate comprising said poor antiknock gasoline, and lighter fractions comprising atleast a major portion of said paraiiinic gases, subjecting said distillate to conversion conditions regulated to effect the production therefrom of high yields of good antiknock gasoline and substantial quan- 15 titles of readily polymerizable normally gaseous olefins, recovering said good antiknock gasoline from the resulting conversion products in the form of a distillate substantially free of dissolved normally gaseous olefins. contacting the last named distillate with said lighter fractions resulting from the distillation step at a sufiiciently low temperature to absorb therein substantial quantitles of said paraffinic gases, stabilizing the resulting gas-containing distillate to a vapor pres- 2: sure materially in excess of that of the second named distillate, recovering the stabilized distillate, and separately recovering from said conversion products a mixture of normally gaseous hydrocarbons containing a high concentration of readily polymerizable olefins.

5. A process such as defined in claim 4, wherein at least a portion of the readily polymerizable olefinic components of said conversion products is returned to said conversion step and therein further converted in commingled state with the first named distillate to produce additional yields of good antiknock gasoline.

6. A process of converting hydrocarbons which comprises, distilling an oil containing poor anti- 4| knock gasoline and essentially paraflinic gases to recover therefrom as separate fractions a distillate, comprising said poor antiknock gasoline, and lighter fractions comprising at least a major portion of said parafiinic gases, subjecting said 4'4 distillate to conversion conditions regulated to effect the production therefrom of high yields of good antiknock gasoline and substantial quantities of readily polymerizable normally gaseous olefins, recovering said good antiknock gasoline 54 from the resulting conversion products in the form of a distillate substantially free of d ssolved normally gaseous olefins, contacting the last named distillate with said lighter fractions re sulting from the distillation step at a sufliciently 54 low temperature to absorb therein substantial quantities of said paraffin gases, stabilizing the resulting gas-containing distillate to a vapor pressure materially in excess of that of the second named distillate, recovering the stabilized 6| distillate, contacting normally gaseous components of said conversion products with regu'ated quantities of the first named distillate to absorb in the latter substantial quantities of readily polymerizable olefinic gases, and supplying the 61 resulting gas-containing distillate to said conversion step.

'7. A process of converting hydrocarbons which comprises, distilling an oil contain ng straightrun gasoline and essentially paraffinic gases to 7 separately recover therefrom a distillate. comprising substantially all of its poor antiknock, straight-run gasoline fractions, and a lighter product containing good antiknock, straight-run gasoline fractions and at least a substantial quantity of said paraflinic gases, subjecting said distillate to conversion conditions regulated to effect the production therefrom of high yields of good antiknock gasoline and substantial quantitles of readily polymerizable olefinic gases, recovering the last named good antiknock gasoline from the resulting conversion products in the form of a distillate devoid of at least a major portion of said normally gaseous olefins, commingling the last named distillate, with said lighter product of the distillation step to include therein, with said last named distillate, as the gasoline product, said good antiknock straight-run gasoline and a substantial quantity of said paraifinic gases, and separately recovering from said conversion products a mixture of normally gaseous hydrocarbons containing a high concentration of readily polymerizable olefins.

8. A process such as defined in claim '7, wherein at least'a portion of the readily polymerizable olefinic components of the conversion products is returned to said conversion step and therein further converted in commingled state with the first named distillate to produce additional yields of good antiknock gaso ine.

9. A process of converting hydrocarbons which comprises, distilling an oil containing straightrun gasoline and essentially parafiinic gases to separately recover therefrom a distillate, comprising substantally all of its poor antiknock straight-run gasoline fractions and a lighter product containing good antiknock straight-run gasoline and at least a substantial quantity of said paramnic gases, subjecting said distillate to conversion conditions regulated to effect the production therefrom of high yields of good antiknock gasoline and substantial quantities of readily polymerizable olefinic gases, recovering the last named good antiknock gasoline from the resulting conversion products in the form of a distillate devoid of at least a major portion of said normally gaseous olefins, commingling the last named distillate with saidlighter product of the distillation step to include with said last named distillate, as the gasoline product, said good antiknock, straight-run gasoline and a substantial quantity of said paraflinic gases, contacting normally gaseous components of said conversion products with regulated quantities of the first named distillate to absorb in the latter substantial quantities of readily polymerizable olefinic gases, and supplying the resulting gascontaining distillate to said conversion step.

10. 'A process of distilling and converting hydrocarbon oils which comprises, heating charging oil containing poor antiknock gasoline fractions, and essentially parafiinic gases to distillation temperature and separating therefrom by fractionation a substantially gas-free condensate comprising said poor antiknock gasoline fractions, converting said condensate under conditions'of high cracking temperature and substantial superatmospheric pressure to produce therefrom substantial yields of gasoline of improved antiknock value and olefinic gases, separating said good antiknock gasoline and gaseous products of the conversion step from higher boiling products thereof, recovering said good antiknock gasoline in the form of a distillate containing substantial quantities of dissolved relatively heavy gases including readily polymerizable olefins, stabilizing said distillate to a low vapor pressure by liberating therefrom at least a major portion of the dissolved gases, removing as liberated gases from the stabilizing step a mixture of normally gaseous materials containing a high proportion of readily polymerizable olefins, separately removing from the charging stock in the distillation step a low-boiling vaporous stream comprising substantially all of the gaseous components of the charging stock, commingling said vaporous stream with the stabilized distillate,

cooling the mixture sufliciently to retain said stabilized distillate in liquid state and absorbing therein substantial quantities of the heavy ga'seous components of the charging stock, and stabilizing the resulting gas-containing distillate to form a final gasoline product of the desired vapor pressure.

11. A process such as defined in claim 10,

wherein gases liberated in the first mentioned stabilization step are condensed to form a normally gaseous condensate containing a high concentration of readily polymerizable olefins.

12. A process such as defined in claim 10, wherein gases liberated in the first mentioned stabilization step are condensed to form a normally gaseous condensate containing a high concentration of readily polymerizable olefins and wherein regulated quantities of said condensate are returned to said conversion step for further treatment in commingled state with the first mentioned condensate.

3. A process such as defined in claim 10 wherein gases liberated in the first mentioned stabilization stepare intimately contacted with regulated quantities of the "first mentioned condensate to absorb in the latter substantial quantitles of readily polymerizable normally gaseous olefins and the resulting gas-containing condensate supplied to said conversion step.

14. A process such as defined in claim 10, wherein said vaporous stream recovered from the distillation step includes good antiknock gasoline components of the charging stock which are condensed in said cooling step and included, with said heavy paraflinic gases and the'good anti-knock gasoline resulting from said conversion, in the gasoline product resulting from the final stabilization step,

15. A process of distilling and converting hydrocarbon oils which comprises, heating crude petroleum containing gasoline and paraffinic gases to distillation temperature and separating the same ,by fractionation into a condensate, comprising poor antiknock gasoline fractions, and lower boiling and higher boiling fractions, substantially stripping the condensate of desirable light components including dissolved gases and thereafter converting the same by heat and pressure treatment into high yields of good antiknock gasoline and substantial quantities of olefinic gases, cooling the heated products of the conversion step sufficiently to prevent excessive further conversion thereof and separating the same into vapors and non-vaporous residue, fractionating the vapors to condense therefrom components boiling above the range of the de-- sired gasoline, subjecting the fractionated vapors to condensation, separating the resulting distil late and uncondensed gases under conditions regulated to include in the distillate at least a major portion of the heavy, readily polymerizable, normally gaseous olefins produced by said conversion, stabilizing the distillate to a vapor pressure substantially lower than that of the desired final gasoline product by liberating therefrom regulated quantities. of its gaseous components, removing as thus liberated gases from the stabilization step a mixture of normally gaseous materials containing a high proportion of readily polymerizable olefins, removing said lower boiling fractions of the crude as a vaporous stream from the first mentioned fractionating step, subjecting the same to condensation in commingled state with distillate resulting from said stabilization, separating resultant distillate from uncondensed and undissolved gases under conditions regulated to retain in the distillate a substantial quantity of the heavy paraflinic gaseous components of the charging stock, and separately stabilizing the last named distillate to form said final gasoline product of the desired vapor pressure.

16. A process such as defined in claim 15, wherein gases liberated in the first mentioned stabilization step are contacted with an absorber oil comprising regulated quantities of the stripped condensate recovered from the crude oil distilling step and the resulting enriched absorber oil supplied to said conversion step.

1'7. A process such as defined in claim 15, wherein gases liberated from the distillate in the first mentioned stabilization step and gases previously separated therefrom are contacted with an absorber oil comprising regulated quantities of the stripped condensate recovered from the crude oil distilling step and the resulting enriched absorber oil supplied to said conversion step. 7

said oil and separating the parafilnic gases from 3 the low anti-knock gasoline fractions, subjecting the latter to reforming conditions of temperature and pressure and separating from the resultant products a gasoline distillate containing a substantial amount of dissolved olefinic gases, stabilizing said distillate to a lower vapor pressure than commercial gasoline, thereby separating from the distillate normally gaseous olefins suitable for polymerization, and combining with the stabilized distillate a suflicient amount of said paraflinic gases to raise its vapor pressure to that of commercial motor fuel.

20. The process as defined in claim 19, further characterized in that at least a portion of said normally gaseous olefins is subjected to the reforming conditions together with said low antiknock gasoline fractions whereby substantial polymerization thereof is effected.

CHARLES H. ANGELL.

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