US2090007A - Manufacture of motor fuel - Google Patents

Description

Aug. 147, 1937. K. G.' MacKENzn-z MANUFACTURE oF MOTOR FUEL Filed Sept. 26, 1928 2 Sheets-Sheet 1' vwantoz u Hl... MNH..

Aug. 17, 1937. K. G. MacKENzlE 2,090,007

' MANUFACTURE oF MOTQR FUEL Filed Sept. 2.6, A1928 2 Sheets-Sheet 2 Patented ug. il?, i937 MANUFACTUBE or Moron FUEL Kenneth G. Mackenzie, Westport, Conn., asl* `signor to The Texas Co., New York, N. Y., a

corporation oi' Delaware Application September 26, 1928, Serial No. 308,535

4 claims. '.(ci. 19e-z3) v This invention relates to the production of light hydrocarbons, such as gasoline, and contemplates certain novel methods of treating and blending hydrocarbon vapors and distillates derived from the distillation of petroleum and other hydrocarbon oils with or without decomposition.

This application is a continuation in part of my co-pending application, Serial No. 565,626, filed June 3, 1922.

In cracking hydrocarbon oils for the production of gasoline therevis usually formed a greater or less amount of so-called'wild gases. 'I'hese gaseous constituents generally consist of some permanent gases containing in solution quantities of condensable vapors. It is considered desirable to incorporate as large a proportion as possible of these light products in the liquid gasoline and consequently it has been sought to retain the wild constituents in the condensate derived from the cracking operation by condensing under superatmospheric pressure. Sometimes blending is resorted to and th'e wild gases are Yadmixed, usually while under compression, with untreated petroleum distillates, the`product thus obtained being subsequently 'distilled to yield fractions of desired boiling point.

Whatever may have been the precise method of obtaining the mixture containing the wildA comparativelyl large proportion of unsaturatedcompounds which react violently with reagents such as sulfuric acid and aluminum chlorid, with the evolution of considerable heat. The result is that great quantities of the lighter products which have been incorporated in the liquid are volatilized-and lost. In addition to the losses resulting from chemical action and heatv great losses also occur from the mechanical action of the agitation usually accompanying the treatment. Thus present methods of treatment are very wasteful and inefilcient.

The primary object of my invention is to avoid the losses which characterize present rmethods of treating and handling cracked products and to so treat cracked constituents thatmarketable products are obtained. In accordancel with my invention, therefore, the wild gaseous constituents derived from the cracking operation are segregated from the more easily condensable bodies which may then be purified by treatment with suitable reagents. 'The constituents thus segregated,either in the form of vapors or condensates, are then admixed with a liquid product that has been treated with a suitable acid or other puritying agent, the light constituents and the heavier treated liquid being blended in suchv proportions that the resultantliquid product. will have the specifications required Yfor the product desired. The desired boiling range of the heavy treated liquid or distillate is preferably secured prior to the blending by means either of condensers or, by ie-distillation, thereby avoiding unnecessary losses of the light constituents which would otherwise occur if distillation were resorted to subsequent to the blending operation. In some cases the wild constituents are filtered or treated to remove color bodies or material held insuspension or they are treated with alkalies or other suitable purifying agents prior to the blending with the liquid base.

One feature of the invention involves the blending of the wild cracked constituents or condensates therefrom with a hydrocarbon distillate having a boiling point range of that ci the heavier constituents of gasoline. .Thelighter products entering into the mixture furnish the lower boiling point constituents ofthemotor fuel and the result is vthat a product having the ylow initial boiling point desired for easy starting in hydrocarbon motors and having .also a sumciently high boiling fractionto give thedesired caloriilc power, is produced.

Iny order to more fully disclose my invention, I will n'ow proceed to describe the methods of operation, reference being had to the accompanying drawings in which Fig. 1 is a diagrammatic elevation of an apparatus adapted for carrying out the invention and Fig. 2 is a diagrammatic elevation of a modified form of apparatus.

A il designates an apparatus forcracking oil and may be of any desired character, it being understood that my invention has no reference to any particular method oi' carrying on the cracking operation per se.A vThe apparatus may be equipped with a vapor line Ii leading to a suitable air condenser or separator I2. having a reiluxpipe I3 adapted to return -to the cracking zone the insumciently cracked constituents. A vapor line i4 extends from the? separator |2,^or directly from the cracking apparatus, if desired, to thecondensing coil I5 which is preferably water-cooled. Interposed between the still and condenser there is a pressure relief valve i6.- When using an air condenser, such as the separator I2, it is generally desirable to place the pressure control valve in the outlet from the separator rather than in the vapor line and accordingly the valve i6 has been shown as being in the line I4. The valve |6 is used to hold the hydrocarbons in the still or converter |0 at the desired pressure and also serves to reduce the pressure in the condenser I5 so that condensing may be carried on at comparatively low pressure, for example at atmospheric pressure. It is to be understood that the practice of myfinvention is not confined to a method of operation in winch condensing is car-` ried on at atmospheric or low pressure but it is usually preferable when employingmy process to condense at'substantially atmospheric pressure'.

The condenser is equipped with an outlet Il which leads to the receiver Il wherein the condensate is collected. A pipe I! conducts the uncondensed constituents, including the wild gases, to a compressor or absorber or other blending apparatus wherein the vapors and gases are admixed with a treated hydrocarbon oil. `It is sometimes desirable to treat the gases and vapors with certain chemical reagents inforder to revmove sulfur compounds andin order to remove color materials. v',I'he pipe Iiis therefore shown as extending to one or moretreating chambers Y such as the vessels and 2 I. The treating chaxri- Vterial.

bers are preferably provided with contact material, and with spray pipes, such as 22. by which chemicals may be sprayed over the contact ma- In. the drawings I have illustrated the treating vessels as consisting of the two towers 20 and 2| butit isto be understood that any convenient number may be used, the number employed being dependent upon the'character of l the impurities in theV vapors and gases and upon the character of the chemical used. Each tower is equipped with an outlet pipe 23v by which the vapors from yone treating chamber to the next in succession andan outlet pipe 25 is provided for the last treating vessel, such as 2|. If desired, the v4treating vessels may be enclosed inl heating jackets or otherwise heated in order to prevent any material condensation of the gases and vapors while being treated as I have found absorption, yor other blending apparatus. .lisy

that when treating withalkau solutions, for example, there is a greater, tendency toward the Vformation of emulsions if the constituents being `treated are in ai., liquid state than if they are in the form of vapor. y The pipe25 extends to a .suitable compreion,

'shown in therdrawings itterminates in the absorbing chamber .26 v,wliichpreferably contains suitablecontact` material and is provided with a spray pipe 21 by which the liquid which is to be blended with the vapors andgases is admitted to the absorption chamber. It is to be understood that Amy invention is Vnot limited tothe use of absorption as a means of blending gases with liquids but Vthat compression as well asV other equivalent means mayV beused in theblending operation. I ilndit is generally desirable, however, to use absorption'since the product obtained is generally more stable than oneproduced by compression. The absorbing chamber 2631s provided with the gas outlet 28, and with a liquid outlet 29' by which the blended product is ,con-

ducted to a receiver 30.

In the preierredmethod of operation a suitable hydrocarbonl oil issubjected to Vpyrogenic decomposition and thevaporous products of the reaction are allowed to pass to the condenser l' wherein condensation is eiected at substantially atmospheric pressure. In this method of oper,- ation there `will be a much greater proportionof bodies uncondensed in the condenser coil 'than when condensation is carried on under superatmospheric pressure. The condensed fluids commingled with the vapors and gases, including the wild constituents, are passed into the receiver I8' wherein the condensate is collected. The liquid product thus collected in theV receiver constitutes what is commonly knotvn as cracked naphtha distillate and may be purified by treatment with suitable reagents such as aluminum chlorid, sulfuric acid, alkali solutions and other well known purifying materials, in order to produce a marketable product such as is adapted for fuel for an internal combustion engine. The unfcondensedv constituents are conducted by the vapor line I9 directly to a blending chamber or else `to such treating or filtering means 'as may be desired.

Y The purifying treatment rgiven the gaseous constituents is dependent upon the characterof'the impurities, the extent, to which the impurities are present and the proportion of A,gaseous prod-v ingthe bulk, of the impurities in one treating vessel, as the tower 20, and toi use in a second tower, as 2|, 'a more expensive material 'capable of removing impurities which'were not attacked by. the chemical in theflrst tower. 'Ihus it has b'emfound advantageous to pass Vthe gaseous products `first through a lime solution and then through a'lead-soda solution.' The chemical reagents used may be either in 'the' form ofk solutions or in the form of dry` material 4through which the vapors are permitted to pass. Various chemicals have been foundadvantageous, such as lime. lead-soda, soda ash, potassium carbonate, caustic soda, lye, ironfoxid,and thelike. It is often advantageous to. treat the gases with a comparatively cheap reagentr such as milk of lime'and then to pass the treated 'gasesA through fullers earth'or'charcoal to remove color bodies or other materials held in suspensionvin fthe a blended liquid product having the charac-Y teristics desired. The product admitted through the pipe 21 comprises a'treated product, such as a petroleum distillatewhichhas been treated with sulfuric acid, aluminum chloridI or other `reagent, and is of such'nature that it will pass the standard tests for marketable products.' `-JI'he treated liquid base is blended with the gaseous constituents including the so-called wild gases derived from the cracking of hydrocarbon oils. The liquid base may be a product derived from 5 the decomposition of hydrocarbons or from the simple distillation thereof. Thus the liquid base may be either a cracked naphtha distillate which has been suitably purified or a naphtha distillate produced by mere fractionation and proper puril fying treatment. I have Vfound that certain of these gaseous products may be blended without treatment of any kind with a treated hydrocarbon distillate and if the proportion of untreated bodies and treated liquid is properly adjusted the resultl ant blended product will be found to be suitable for the market. As has been pointed out, with some of the gases a, chemical treatment, such as an alkali treatment or the passing of the gases through filters or separators, may be necessary. 9A) This is especially true in the case of gases derived from Mexican crude and similar petroleums which have comparatively large proportions of sulfur compounds, and in which case chemical purification is usually required. In any case the practice of my invention avoids the treatment of the blended product by agitation with the resultant loss of the lighter bodies by mechanical action and also avoids treating the blended product with an acid, such as sulfuric acid, or with aluminum chlorid, or other reagent in which heat is generated during the 'reaction and in which substantial losses occur due to volatilization of the lighter products. By means of my invention the lighter vapors and gases, including the wild constituents, are so treated and blended with a, nished stock that these losses are avoided.

'I'he character of the purifying treatment accorded the light vaporous fractions, which include the wild gases, depends very largely upon 40 the crude oil source from which these fractions may have been derived. In most cases, however. a treatment comprising the passing of. the vapors through suitable adsorbent material or alkali solution has been found to be adequate. 'I'he vapors thus purified are then blended with the liquid base which has been properly purified. The treatment required for the liquid base is generally different from that given the lighter fractions; the heavier liquid base must generally be treated with more powerful reagents, such as sulfuric acid, aluminum chlorid and the like, in order that the ultimate blended product will meet the specifications desired. In blending the lighter fractions with the liquid base the lighter bodies may be in the vapor form or they may be cooled sufliciently or otherwise treated to produce a liquid or condensate which may then be admixed with the liquid base.

In one method of practicing my invention in- 0'0 stead of following the lusual procedure of blending the lighter gases with a comparatively heavy stock and then distilling the blended product in order to yieldia distillate of desired tests I have found it generally more economical to blend the light constituents with a product, which when so blended will yield a product having the desired tests. 'I'hus in the production of motor fueFI have used successfully a liquid base having an initial boiling point around 280 F.300 F. and

an end point of about 400 F.425 F, by admixing this product, which it will be noted comprises largely the heavier fractions of gasoline (according to standard specifications now in use), with a light volatile product derived from the cracking of hydrocarbon oil and comprising (as it came from the condenser) a gas or a gaseous product containing condensable vapors in solution, the blended product having an initial boiling point of about 85 F.100 F. and an end point 4of 400 lit-425 F. This type o'f product contains 5 sufficiently heavy constituents to give a high calorific value to the gasoline and at the same time its low initial boiling point makes it susceptible of easy starting in hydrocarbon motors. This preliminary determination of the boiling range of 10 the liquid base before the blending step may be accomplished by means of condensers or by redstillation and thus avoids losses of the lighter constituents otherwise incident to the usual fractional distillation subsequent to the blending op- 15 eration.

In the practice of my invention various modifications may be made from that which has been described specifically in this specification. For instance, in one method of operation the wild 20 gases may be subjected to compression to produce a liquid product which may subsequently be blended with a reagent-treated liquid. In another method of operation instead of holding the temperature in the final condenser, which` re- 25 ceives the products derived from the distillation or cracking of hydrocarbon oils, at atmospheric temperature or thereabouts, such as is commonly done, a comparatively high temperature may be maintained in order to collect a liquid at such a temperature that it will not be possible for any material quantity of wild gases to be present theren. This liquid may be drawn o to a .cooler and treated as may be desired. The vaporous product which contains the Wild gases mayvthen 35 be removed from the high temperature receiver and treated by any of the methods which have been described herein for handling the gases and vapors. I

In Fig. 2 a furnace 35 having a burner 36 sur- 40 rounds a heating coil 31, in which oil may be raised to a cracking temperature. and is connected by pipe 38 to cracking still 39. The vapor space of the still 39 is connected by pipe 40 provided with a suitable valve to the lower part of a 45 fractionating column 4I above which is provided an ordinary form of reflux condenser 42 connected by suitable vapor and liquid return lines. The reflux condenser 42 is connected by a pipe I9 to a treating chamber 20 similar to thatshown in 50 Fig. 1. 'I'he pipe 43 leads from the liquid level at an intermediate tray in the column 4| to a receiver 44 for liquid condensate. The fractionating column 4I may also be provided with a draw-0E pipe 45 for withdrawing the heavier 55 fractions which may collect at the bottom of the column. The operation of this modified form of apparatus r'nay be similar to that illustrated in Fig. 1.

'Ihe oil in passage through the heating coil 31 'w is raised to a cracking temperature and passed by the pipe 38 to cracking still 39. This cracking still may receive external heat or it may be insulated and suiicient heat be derived from the hot oil entering through the pipe 38. Vapors of 35 the cracked hydrocarbons pass by pipe 40 into the fractionating column 4| where they are separated into three fractions; the lightest fractions pass out at the top of the column and the reflux condenser 42 into pipe I9 and may be retained in 70 vapor state and thus refined in chamber 20 as heretofore described. The intermediate fraction may be drawn off from an intermediate 'tray in the column 4I and flows through pipe 43 to receiver 44 from which it may be drawn off and 'I5 treated in any suitable manner. The heaviest fraction collects at the bottom of the column Il and may be drawn off through the pipe 45 and may serve as a stock for further cracking.

The oil in heating'coil 3l and in still 39 may be and preferably is under substantial pressure and this pressure may be carried through the fractionating column 4| and reflux condenser 42 by maintaining the valve in pipe I! partially closed. In another method of operation the pressure may be reduced before the vapors reach the fractionating column Il by the valve in pipe 40.

In the operation'Y of this apparatus it may be desirable to allow vapors to pass out of the reflux condenser 42 which will produce a condensate having a relatively low end boiling point, as for example 250 to 300 F. These light vapors may receive a suitable treatment in column 20, which as previously pointed out may be less drastic than that necessary to suitably, refine a heavier condensate; thesevapors may be refined either while maintained in vaporous condition, or they may even be cooled and condensedk and refined in liquid state. The intermediate fraction which may be drawn off through the pipe 43 may suitably have anend boiling point of 400 to 425 F. After the vapors in chamber have been refined they may be blended, as previously pointed out, with heavier refined oil to produce a suitable motor fuel. This heavier-oil may suitably be the 'refined condensate from the receiver M;

It is well known that as a result of cracking reactions a mixture of hydrocarbons is produced. Some of these hydrocarbons are gases at normal atmospheric pressures and temperatures; these are-the most, volatile. Next in order of volatility are thehydrocarbons having relatively low boiling points, but which are normally liquids. Both these classes of hydrocarbons are present inthe commercial' motor fuel which is a mixture of these hydrocarbons with still heavier hydrocarbons having higher boiling points, and therefore of lower volatility. The gaseous and low boiling hydrocarbon constituents of motor fuel, on account of their great volatility, have a tendency to escape from the liquid mixture and are those generally termed in the industry wild" constituents. The terms wild gases and/or "lighter constituents" are used throughout the specification to designate those gaseous ,and light liquid constituent-s of motor fuel which have a strong tendency to volatilize and escape, especially upon increases in temperature, such as may readily be encountered in treating.

Obviously.' various modifications of the invention may be effected without departing from the spirit and scope of the invention. The true scope of the invention is defined in the appended claims.

What I claim is:

1. The process of making motor fuel from:

cracked hydrocarbon vapors which comprises separating by fractional condensation a cracked distillate from which the lighter fractions have been separated and which has been refined by l. more drastic refining treatment. whereby a marketable motor fuel is produced.

2. The process of making motor fuel from cracked hydrocarbon vapors which comprises separating by fractional condensation a cracked naphtha distillate as liquid and a lighter fraction. comprising substantial amounts of motor fuel constituents, subjecting the lighter fraction to a relatively mild refining treatment with an alkaline reagent and blending the refined lighter fraction with cracked naphtha distillate from which the lighter fractionsv have beenv separated and' which hasv been refined by a more drastic treatment including treatment with sulfuric acid. whereby a marketable motorl fuel isv produced. 3. The process of making motor fuel from cracked hyrocarbon vapors which comprises separating by fractional condensation Va cracked naphtha distillate as liquid anda lighter fraction comprising substantial amounts of motor" fuel constituents, subjecting the lighter fraction. to a relatively mild refining treatment such asto eect no substantial loss of valuable unsaturated hydrocarbons, and blending the refined lighter fraction with cracked naphtha distillate from which the lighter fractions have been separated and which has been refined by a more drastic treatment including treatment with sulfuric acid, whereby a marketable motor fuel is produced. 4. The process of making motor fuel from cracked hydrocarbon vapors which comprises separating by fractional condensation; a cracked naphtha distillate as liquid and a lighter fraction comprising substantial amounts of motor fuel constituents, subjecting the lighter fraction to a. relatively mild refining treatment comprising Contact with fullers earth, and blending the refined lighter fraction with cracked naphtha distillate from which the lighter fractions have been separated and whichA has been refined by a more drastic treatment incdluding treatment with sulfurie acid, whereby a marketableymotor fuel is produced. y e

KENNETH G. MACKENZIE.

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