US2032330A - Gasoline manufacturing process - Google Patents

Description

Feb. 25, 1936. ,J. K. ROBERTS El AL I GASOLINE MANUFACTURING PROCESS Filed March 50, 1934 m NN Q LmEKSm NW mm QQEm 5 386% In 0 enters Q Josep/zjckoberw N Morris Z'arpe/zter I I I a l. ATTORNEY Patented Feb. 25, 1936 UNITED STATES PATENT OFFICE GASOLINE MANUFACTURING PROCESS Joseph K. Roberts and Morris '1'. Carpenter, Hammond, Ind., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana This invention relates to a process of manufacturing gasoline and more particularly gasoline derived, to a large extent, from the so-called cracking process. One of the objects of the invention is to produce two grades of gasoline for use in diiierent seasons, specifically, a summer grade for use in warm weather and a winter grade for use in cold weather. Formerly it was the practice to use the same grade of gasoline for all seasons but it has more recently been found desirable to market a more volatile grade of gasoline during the winter season than during the summer season. Higher volatility is required in cold weather in order to obtain better starting and warming up characteristics in gasoline engines resulting from more nearly complete vaporlzation of the gasolinein the colder induction system. The volatility of summerga'soline, on the other hand, is limited by the consideration 20 of vapor lock which occurs when the vapor pressure of the motor fuel is sufliciently high to interfere with proper carburetion. A most convenient indication of the suitability of the gasoline in use in winter is the percent distilled of! 25 at 158 F. in an Engler distillation. The suitability of a summer gasoline for use without vapor locking trouble is best expressed by the Reid vapor pressure described as A. S. T. M. Tentative Standard-D 323-32T.

30 A specific object of this invention is to produce from a given source of supply of gasoline a winter gasoline having a maximum volatility as measured by percent of! at 158 F. and a summer gasoline having a minimum tendency to vapor locking as measured by the Reid vapor pressure. A still further object of the invention is to produce such winter and summer gasolines from a gasoline stock of substantially unvarying composition without adding or discarding any 40 valuable component thereof.

The invention will be readily understood by reference to the accompanying drawing which shows diagrammatically a. plant suitable for carrying out the necessary operations. Referring -15 to the drawing, a gasoline supply is indicated by tank I which may contain stabilized end point gasoline produced by a cracking process or a blendof cracked gasoline and virgin gasoline from crude distillation. Gasoline is withdrawn so from supply tank [by line 2 and pump 3 to fractionator l where it is subjected to rectification by heat which is supplied to rebelling coil 5. The purpose of this rectification is to remove from the gasoline a substantial part the butane and mnmne' fractions. The butane fraction is with.

drawn from the fractionating column in the form of vapor and passed by vapor line B to condenser I. The liquefied butane is collected in receiver 8 from whence it is discharged by line 9 through valve In and into butane storage tank II. The fractionator 4 is preferably operated under suflicient pressure to obtain condensation of the butane vapors in the condenser I at ordinary cooling water temperatures. A pressure of 50-75 lbs. gage is sufllcient for this purpose. A reflux 10 coil l2, disposed in the topof the fractionator, supplies the necessary reflux liquid for obtaining separation of the butane from the heavier constituents in the gasoline, or an outside reflux condensation system may be provided. From an intermediate point in the fractionator I there iswithdrawn by line l3 a second fraction consisting largely of pentanes. This stream is introduced into side stripper supplied by heat from re-' boiler coil l5 where butanes are separated from this fraction and returned, in the form of vapors, to the main rectifier by line It. The substan- I tially butane-free pentanes are discharged by line H through cooler l8 and into pentanestorage tank IQ.

From the base of the main fractionator 4 there is withdrawn by line 20 the remainder of the gasoline free from butanes and substantially free from pentanes. After passing through cooler 2| this stock is introduced into storage tank 22 where it is retained until further required for blending, as will hereinafter be described. Simultaneously with the operation of fractionator 4,-another stream of gasoline from supply tank I or other source may be passed by line 23 to fractionator 24 which is similar to fractionator 4 and operated under substantially the same conditions of temperature and pressure. Heat is supplied by reboiler coil 25 to efiect satisfactory rectification in. this column and refluxing is obtained by supplying a cooling fluid to reflux coil 26 or a portion of the distillate may be returned for this purpose. Butane vapors withdrawn by line 21 pass to condenser 28 and thence to'receiver 29, whence condensed butane is discharged by line 30, valve 3|, and line 9 into butane storage tank H. The pressure in storage tank ll may be maintained substantially atmospheric by means of suitable heat insulation surrounding the tank and refrigerating means to maintain the contents of the tank at a sufilciently low temperature to prevent excessive loss by evaporation in any season, or if desired, the contents of tank ll maybe held under slight pressure. 1 Gasoline which may be substantia1ly butanefree is withdrawn from tower 24 byline u to is withdrawn from tank 34 by pump 42 and line 43 to mixer 44 where it is blended with pentane removed from tank I! by pump '45 and line 48; after mixing in mixer 44, the resulting stock is transferred by line 41 to gasoline storage tank 40. Ordinarily the'desired amount of butane will be obtained in the winter gasoline by allowing some butane to remain in the gasoline from supply tank I. In order to obtain increased flexibility, however, butanes maybe withdrawn from tank II by pump 38, line 39, valve and line II to mixer 44 where they are blended-with the winter gasoline stock in. the desired amount.

. It should he understood that in the foregoing discussion the terms butane and pentane. are used to describe stocks comprised chiefly of these hydrocarbons and that for practical operation these stocks will contain a certain percentage of other hydrocarbons closely related in boiling point; for

example, the butane fraction may contain from 25 to 30% of pentanes, whereas the pentane fraction may convenientlycontainfrom 15 to 20% of butanes on the one hand and 15 to 20% of hexanes on the other. It is obviously not essential to separate from the gasoline pure butanes 'and pentanes for blending purposes.

The composition of-the fractions which are produced' will natm'ally be consideredwhen calculating the proportions to use in subsequent blends. I

In a typical operation, cracked gasoline which has been stabilized to remove substantially all of the undesired wild" hydrocarbons presents the following analysis: 7

Heavier oonstitnents Percent oil at 158 F.

' Butanes Pentanee m 411% mesa; 11.5% -78.0%' 10.8lbe. .22.

One part oi'this stock gasoline is fractionated 1h tower 4, removing therefrom substantially all the butanes or 10.35% of the gasoline, and a large part of the pentanes as required, in this case 10.9% of the gasoline. Another portion of the stock, in this case an equal volume, is fractionated in tower 24 where a substantial amount of its butane content is removed, for example 5% of thestock. 1 v V v In preparing the desired summer and'winter gasoline, suiiicient butane from tank] I is blended with gasoline from tank 22 to produce a summer gasoline of approximately the following composit n: '1

Heavier Reid Pceent Propane Butanm' Pnntanu constit- -ofl at uents W 158 F.

0.1% an, -'a1% i 85.9% aims. 11.0

n will be noted that the We of butanea in' purposes, as herethis gasoline exceeds the amount of pentanes by 11.9% and that the mid of-pentane to butane is 0.76. v a

In making the winter gasolinesuiilcient pen- "time is withdrawn from tankl! and blended with gasoline from tank 34 to produce a winter gasotion: g

Heavier Percent Reid vapor Propane Butanes Pentanee cagisltuit pmum lag r}:

c193 12 8% 11% 10.1% 12. o lbs. 40

In the above analyses the term propane is inline having approximately the following compositended to include both propane and propylene,

the term butane includes all the four carbon atom hydrocarbons present in the gasoline and the term pentane includes all the five carbon atom hydrocarbons present.

Another example of our invention is illustrated in the following table:

Exampl 2 .Geeoline Summc Winter gasoline gasoline Still another example of our invention is shown in the following table;

Emmple: v

decline Hummd Wintc stock gasoline moiine 'oti 0.1 0.! 10.3 10.5 10.0 12.4 1.5 29.0 7-7.2 87.9 81.9

It will be noted that the ratio of pentane to butane in the. summer and winter gasolines dif-' fers very greatly. In the Examples 2 and 3 this ratio'in summer gasoline is only 0.11 and 0.14 respectively, whereas in winter gasolines the ratio is 3.6 and 2.9. This ratio is characteristic of our winter and summer g 'andis always lower 7 for the summer gasolinethanfor'the winter gasoline. It will be noted amount of butane in the gasoline-exceeds the amount of pentane by 9% in this example.

Fromtheseanalyse'sitwillbeobservedthat starting with a stock which is satisfactory neither forwinternorsmnmerusebecauseitis oftoolow volatility for winter and too high Reid vapor pressure for summer, we have produced a winter and summer gasoline suited for the requirements of these This is accom-. -plished principally by the novel expedient of removing a large part or the pentane fraction from V thesummergasolinestockandadding'ittothe winter gasoline stock, at the same time replacing the'pentanes removed from the gaso-- line stock-by butanes. 'Iheresult is a winter gasoline of high volatility andjrelatively low va-' por pressure, owing itsivolatility largely to pentanes; and a summer gasoline of relativelyJow volatility but vet quite satisfacixrv for summer gasoline over ordinary gasolines owing their vol-' atility largely to pentanes and heavier hydrocarbons lies in its lower tendency to vapor lock in hot weather when compared with ordinary summer gasolines having the same Reid vapor pressure. This advantage is apparently due to the loss of butane which occurs in handling in hot weather and which has a greater influence inlesser amount of vapor is formed, thereby resulting in less trouble or vapor lock, inasmuch as the relation of vapor pressure to percent evapofated is represented by a steeper curve than in the case of ordinary summer gasolines depending for their volatility on a large content of pentane.

In carrying out-the process of this invention we may employ a distillate directly from the cracking operation, containing both lighter and heavier hydrocarbons than desired in the gasoline. In

this case it is preferred to carryout the fractionation for the separation of butane and pentane under higher pressures than those described and eliminate the propane in the same operation as used to separate butane and pentane. In this case it is also convenient to employ a single fractionating column and. remove the butane from a side stripper, much as shown for removal of pentane in the apparatus described herein. The wild gases, including propane and ethane, may also be rejected along with some butane to be later recovered by an absorption process from which the butane is fractionated from the propane and returned to the system. Where the pressure distillate contains hydrocarbons boiling above the desired end point, these'are eliminated by a redistillation of the gasoline. This may be accomplished by flash evaporation of the stock flowing from the bottom of the fractionating tower and distillation of the remaining unevaporated stock to obtain the desired end point. This unevaporated stock may be treated with sulfuric acid or fullers earth before final distillation for the improvement of'gum stability, color etc. and

antioxidants may be added to the finished gaso line.

In applying. our process to the operations of a petroleum refinery it will sometimes "be desirable summer gasoline while in the fall and winter it' may be desirable to produce winter gasoline only. Under these conditions we may retain in storage pentane produced in the summer gasoline manufacturing operation and draw upon this storage of pentane when it is desired to produce winter gasoline or, vice versa we may store up butane produced in the winter gasoline manufacturing operation and retain it in storage, refrigerated or under pressure, or blended in heavier gasoline stocks until required for use in manufacturing summer gasoline. This feature of the process makes it particularly suitable for meeting varying demands of diiferent gasolines and avoids the necessity of carrying large'stocks of one gasoline or the other from one season to the next where this is not desired, as in the case of a shortage of storage capacity@ It should be understood that our invention is not limited to producing any specific vapor pressure or degree. ofvolatility in summer and winter gasolines and we do not intend to be limited by the examples set forth. 'We ordinarily e'mploy our process, however, to produce winter gasolines having a volatility of between 30 and oil at 158 F. and a Reid vapor pressure of between 10 and 16 lbs. The summer gasolines produced by our process will ordinarily possess vapor pressures below 10 lbs.Reid and usually between Sand 9 lbs. Reid while the percent evaporated at 158 F. will usually be from 7 to 18%. The volatility of the winter gasoline will always be higher than that of the summer gasoline and this will be true .of the vapor pressure also.

We claim: I

1. The process of producing winter 'and'summer gasolines from a single gasoline supply of relatively unvarying composition, comprising fractionating a portion of said supply gasoline to remove therefrom a fraction rich in pentane hydrocarbons and produce a gasoline deficient in pentane hydrocarbons but suitable for summer gasoline requirements characterized by hav ing a ratio of pentanes to butanes less than 1 and morethan 0.11 and a volatility of between about "I and 18%oif at 158 F., and combining said pentane-rich fraction with a further quantity of said supply gasoline to produce a gasoline having a higher concentration ofpentane hydrocarb ons'suitable for winter gasoline require-' ments.

2. A motor fuel adapted for use in warm weather comprising a mixture of hydrocarbons boiling within the gasoline boiling range and containing hydrocarbons of the aliphatic series beginning with butane and pentane and substantially free from propane contamination, characterized by having a ratio of pentane hydrocarbons to butane hydrocarbons less than one and more than 0.11 and between about 7 and 18 percent evaporated at 158 F. v

3. The process of producing from a single supply of gasoline of unsuitable volatility and vapor pressure characteristics for either summer or winter use, a winter gasoline having a vapor pressure of between 10 and 16 pounds Reid and a percent-evaporated at'158" F. between 30 and 45 and a summer gasoline having a vapor pressure a between 6 and 10 pounds Reid and a percent evaporated at 158 F. of between '7 and 18, and further characterized by having a ratio of pentanes to butanes less than 1 and more than 0.11 comprising removing pentane hydrocarbons from a 4. The method of producing satisfactory summer winter gasoline from a single gasoline supply of relatively constant composition but un-' suitable for either summer or winter use because 'ofexcessive 'vapor pressure for summer and insufiicient volatilityfor winter, comprising removing pentane from one portion of said gasoline supply to reduce the pentane content substantially below the content of butane thereof, and incorporating said, pentane in another portion of said 7 adapted for summer gasoline requirements, comprising a petroleum hydrocarbon distillate boiling within the gasoline boiling range having a volatility of about 7 to 18% oil at 158 F. and

' containing fractions boiling within the range of butanes and pentanes, the amount of said butane wfraction exceeding the amount of said pentane fraction by from 1.9 to 9% of said total gasoline. 6. A motor fuel adapted for use in warm ieathercomprising a mixture of hydrocarbons boiling within the gasoline boiling range and containing hydrocarbons of the'aliphatic series beginning with butane and pentane and substantially'free from propane contamination, characterized by having a ratio of pentane hydrocarbons to butane hydrocarbons within the range of about 0.14 and 0.76. and further characterized by a volatility between about '7 and 18% evaporated sit-158 r.

, 7. In the process-of producing gasoline havingvolatility characteristics suitable for summer use,

from a supply gasoline of substantially uniform composition, thesteps which comprise removing from said supply gasoline a fraction comprising chiefly hydrocarbons of the butane boiling range,

and a separate fraction comprising chiefly hyd'rocarbons of the pentane-boiling range, leaving a blending stock deficient in both butanes and pentanes, andcombining amounts of the butane boiling range fraction with said'blending stock to give'a product for use as a'summer gasoline -having a Reidflvapor pressure of about 6 to 10 pounds, a volatility of about '7 to 18% 011 at 158 F. and a ratio ofv pentanes to butanes less than 1 and more than 0.11.

8. In .the "process of producing gasolines of. widely diflering volatility characteristics and suitable for winter use and simmer use respectively, from a supply sasoline of substantially uniform composition but having volatility characteristics which as such are not best designed 'for particular climatic conditions, the steps which comprise removing front said gasoline a fraction comprising chiefly hydrocarbons of the'butane boiling range, and a separate fraction comprising ehiefly hydrocarbons of the pentane boiling range, leaving a blending stock deficient in'both butane and pentane, combining amounts of the butane boiling range fraction with said blending stock to give a product having a ratio of 7 to18 ofl' at 158 marmas a summer gasoline, and combining said pentane boiiingrange fraction with supply gasoline whereby a winter gasoline is produced which contains more pentane pentanes to butanes less than 1 and moretnan 0.11, said product having a Reid vapor pressure of about 6 to '10 pounds and a volatility of-about winter gasoline,

boiling range hydrocarbons than are contained in the supply gasoline. I

9. The process of preparing from a supply gasoline a summer motor fuel and a winter motor fuel having desired volatility characteristics, which comprises the .steps of removing from said gasoline two fractions of hydrocarbons, one

of which contains a relatively high concentration tration of pentane and separately collecting said fractions, combining a portion of the fraction relatively high in pentane with a partly debutanized gasoline to prepare said winter motorfuel, and combining a sufllcient amount of the fraction relatively high in butane with a portion of the partially debutanized and depentanizedgasoline to produce a summer motor fuel with a ratio of pentanes to butanes less than 1 and more than 0.11, and a volatility of between about 7 and 18% off at 158 F.

" 10. The process of producing two grades of gasoline from a gasoline supply of substantially uniform composition, one of said grades of gasoline being adapted for use as a summer motor fuel, having a ratio of pentanes to butanes less than 1 and more than 0.11, and a volatility of. betweenabout"! and 18% oil? at 158 F. and the other being adapted as a winter motor fuel, having a higher proportion of pentanes than butanes and a higher concentration of pentanes thanv thatv of the original'supply gasoline, comprising separating from said supply gasoline a fraction -boiling predominantly within the range of hutanes, further separating from said supply gasoline a fraction boiling predominantly within the range of pentanes, and leavinga plurality of gasoline stocks, one of which is deficient in pentanes, combiningsaid gasoline stock deflcientinpentanes with said predominantly butane fraction to produce said summer grade of gasoline and combining another of said gasoline stocks with said predominantly pentane fraction to produce said 11. In the process of adapting the pressure distillate produced by a cracking plant to the varying volatility requirements of winter and summer motor fuels having a Reid vapor pressure between about 10 and 16 pounds and a volatility of pressure between about 6 and 10 pounds and a volatility of about '7 to 18% of! at 158 F. respectively, the steps which comprise forming debutanized and depentanized pressure distillate from the pressure distillatesupply, a fraction .rich in hydrocarbons boiling within the range I of butane, and a fraction rich in hydrocarbons boilingwithin the range of pentane, adding sufficient quantities of the fraction rich in hydrocarbons boiling within therange of butane to some of the debutaniz'ed and depcntanized pressure distillate to produce a summer gasoline of the desired volatility characteristics and havin of butane and the other a relatively high concenabout 30 to oil at 158 FQand a Reid vapor a ratio of pentanes to butanes less" than 1 and more than 0,11, and adding suilicient quantities of the fractionrich in hydrocarbons boiling withnized and undepentanized pressure distillate supply to produce a winter gasoline of the desired volatility characteristics. I 12. In the process of adapting the pressure sure of about 10 to 16 pounds and a volatility 01" about 30 to 45% off at 158 F. and a Reid vapor 7'0 distillate produced by a cracking plant to thev varying volatility requirements of a winter and asummer motor'fuel having a Reidvapor presin the pentane range to some of the undebuta- I a pressure ot'about 6 to 10 pounds and a volatility of about 7 to 18% oil at 158 F. respectively, the steps which comprise forming a partially debutanized traction and a partially depentanized fraction from the pressure distillate supply, a fraction rich in hydrocarbons boiling within the range of butane, and a fraction rich in hydrocarbons boiling within the range of pentane, adding suflicient quantities of the fraction rich in hydrocarbons boiling within the range of butane to the partially depentanized pressure distillate supply to produce a summer gasoline of the desiredvolatility characteristics having a ratio of pentanes to butanes less than 1 and more than 0.11, and addingsuflicient quantities of the fraction rich in hydrocarbons boiling within the pentane range to the partially debutanized pressure.

distillate to produce a winter gasoline of the desiredvolatility characteristics.

13. The method of making seasonal gasolines from a supply gasoline of substantially constant composition which comprises making a summer gasoline of abnormally high vapor pressure with respect to its volatility by removing a suflicient amount of the fraction boiling within the range of pentane from gasolines marketed in the summer season without appreciably affecting the butane content thereof, said summer gasoline being characterized by a volatility of between about 7 and 18% oi! at 158 F. and a ratio or pentanes to butaiies less than i and more than 0.11, and blending said removed pentane fraction with said supply gasoline of substantially constant composition to make a winter gasoline characterized by abnormally high volatility with respect to its vapor pressure.

14. The process of manufacturing gasoline suitable for summer and winter use from the products of a cracking operation containing gasoline and hydrocarbon gases undesirable in the gasolines, comprising eliminating said undesirable hydrocarbon gases together with butane, recovering said butane by an absorption process, separating from said products a portion of the gasoline from which pentane has not been removed, a hydrocarbon fraction boiling predomi antly within the range of pentanes and a portion of gasoline from which pentane has been removed, adding said recovered -.butane to said portion of gasoline from which pentane has been removed to produce a summer gasoline having a ratio of pentanes to butanes less than 1 and more than 0.11, and having a volatility of about 7 percent to 18 percent evaporated at 158 F., and adding said pentane fraction to a portion of the gasoline from which pentane has not been removed to produce a winter gasoline.

JQSEPH K. ROBERTS. MORRIS T. CARPENTER.

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