US1861399A - Art of oil conversion - Google Patents

Description

May 31, 1932 w. G. LEAMON ART oF OIL CONVERSION 2 Sheets-Sheet 1 Filed Nov. 2, 1925 May 31, 1932. w. G. LEAMON ART oFy OIL CONVERSION 2 Sheets-Sheet 2 Filed Nov. 2, 1923 gwvefnfoz Z Z am .eam om,

Patented May 31, 1.932

UNITED STATES- WILLIAM G.

vPA'I'ENT OFFICE LEAMON, or NEWARK, OHIO, AssIeNoa, Bruinsma ASSIGNMENTS, To THE LEAMON. rnooEss COMPANY, A CORPORATION or OHIO ABT or OIL CONVERSION Application led November 2,1923. Serial No. 672,439.

This invention relates to improvements in y art of oil conversion; and it relates more particularly to processes of an -apparatus for treating relatively heavy hydrocarbon oils of the petroleum type for the manufacture of lighter products therefrom, such as motor fuel and the like, wherein conversion of the relatively heavy oil is effected in vapor phase at suitable cracking temperatures and in inti- Y mate association with porous adsorptive con- .tact material of such character that it does not deteriorate or cause coking or other undesirable carbon formation under the conditions Of operation, the procedure being further characterized by the fact that the cracking or converting zone, including the mass of contact material referred to, is maintained at the proper cracking temperatures by the hot oil vapors passed into and through said zone,

without external heating of said zone, whereby the desired conversion of the oil into lighter products is eectedin a simple, eicient and economical manner with great ease of conf trol especially as regards -the maintenance of proper temperature conditions, and with the attainment of other desirable results, as will Lbe hereinafter more fully set forth.

' In 'a' prior copending Aapplication of the present applicant, Ser. No. 512,894, led Noao vember 4, 1921, there is set forth and broadly claimed a process of convertin heavy hydrocarbon oils into ygasoline an similar lowboiling productsl of the motor fuel type,by passing the vapors of relatively heavy oils through tubes Iilled with Orous adsorptive contact material, specica ly 'pumice, said tubes being externally heated to maintain the cracking or converting zone, including the porous contact material, at cracking temperatures favorable to the attainment of a ood yield of the relativel1 low-boiling pr ucts desired. As disclose in said prior application, by proper control and regulation of the operating temperature and other conditions, the desired conversion inthe .manner described can be eected with practcallyfno separation of freecarbon in the cracking zone, and with extremely little separation of free carbon at any int in the entire system. The

process as set Orth in said prior application has been extensively practiced on a commercial scale, and in such actual practice it has been a common thing to operate the cracking or converting tubes filled with pumice practically continuously for months at a time without any cleaning out of the tubes being necessary. Even after continuous Operation for such long periods of time, examination of the tubes and of the contained adsorptive Contact material has shown that only at such' points as may have been subjected to local overheating has any appreciable deposit of free carbon been formed of such character as to. require removal. In the case of such externally ired cracking tubes,'however, it has been found that the inner walls of vthe tube after prolonged use gradually acquire a skin or scale o f carbon in more4 or less coly form, and that'this skin o r scale tends' gra ually to build up as. time goes on thus to a certain extent diminishing the eiliciency ofheat transmission into the interior of the tube. This gradual accretion ory building up of Acoky carbon on the inner tube wills has been especially noticeable along the bottomV of the tube where certain heavy tar-like products incidentally formed in the crackin or converting operation collect and drain ack to the lower end of the tube which is slightly inclined to favor such draining.r Also, 1n cases where for -any reason the external firing of the tubes has been temporarily somewhat excessive, which is sometimes unavOidable in practical Operation, some'of the lumps of pumicenext to the wall of the tube have been overheated with the result that their activity in assisting 'the converting reaction.

undergoneby the heavy oil vapors has been greatly reduced or even entirely destroyed.

As pointed outin said prior application, the cracking or converting temperature should not ordinarily be carried beyond about 600 C. as an extreme upper limit and in fact operation at materially lower temperatures is decidedly better practice and is advisable for attainment of maximum yields of the desired The matter of thus carefully regulating the 'f low boiling products and avoidance of exoesoperating temperatures in the cracking or een Aconverting zone has therefore always one of the factors requiring greatest care and attention in the practice of the process disclosed in the prior application aforesaid; and although long continued practice of said process has been uniformly attended with success, the difficulty of attaining accurate temperature control of the cracking temperature of the tubes externally fired as described, unless such external firing is carefully watched and skilfully regulated at all times, has been pronounced.

It is a principal object of the present invention, therefore, to improve the process generally set forth above and disclosed in said prior copending application in such a way as largely to eliminate the diiiiculty of accurate temperature control in the cracking or converting zone, thereby simplifying the procedure in general and also rendering the desired results attainable with maximum uniformity and dependability. Another object of the invention is to provide apparatus of an improved type wherein the process as modiiied in accordance with the present invention may be carried out to advantage.

Other and more specific objects of the invention, together with further advantages attained thereby, will appear more fully hereinafter.

In its most advantageous practical embodiment, the invention of the present application is characterized by elimination .of external heating of the cracking or converting zone, and by employment of the hot vapors of the oil to be converted as the source of heat, whereby the temperature of the cracking zone is maintained within the proper working limits. A desirable practical Way of carrying this into eli'ect is to thoroughly heat-insulate the cracking or converting zone in order to minimize loss of heat therefrom, and then to ass the relatively heavy oil vapors, into sai zone at such initial temperature and at such rate that the desired crackin or converting temperature will be maintalned. In general, this requires heating the relatively heavy oil to obtain vapors whose temperature is somewhat above that predetermined for the cracking zone and controlling the supply of the hot vapors to said zone in order to` effect the necessary temperature regulation in said zone. This regulation and control can be accomplished in various ways. One desirable way that has given good results in practice is to regulate the firing of the still or vaporizer that supplies hot vapors to the crack. ing zone; and at present this is considered to be the most advantageous method. In this way it is only necessary to see 'that the temperature in the still or vaporizer is kept above a certain minimum and does not exceed a certain maximum, which is something that can be done very easily and does not require a high degree of skill on the part of an attendant; whereas, on the other hand, the accurate maintenance of a predetermined temperature'in a vapor phase crackin tube that is externally fired is a far more dliicult and troublesome matter. Furthermore, the new. method of economy of eat in addition to permitting the attainment of easier and more accurate control of cracking-zone temperatures.

Further explanation of the invention can be most readily given in connection with a concrete example illustrating one practical embodiment of the process as carried out in the novel apparatus system shown in the accompanying drawings wherein Fig. 1 is a diagrammatic layout of a typical apparatus system within the scope of the invention, the various parts being shown in side elevation with the vaporizer in section;

Fig. 2 is a more detailed showing, on a larger scale, of a suitable type of cracking or converting chamber and some of the accessory apparatus, the drawing being a side elevation with parts broken away and i'n section; and

Fig. 3 is a plan of the cracking chamber shown in Fig. 2, partly broken away and in section.

In the typical illustrative example about to be given, it will be assumed that the relatively' heavy oil to be converted into lighter products is a topped crude petroleum, that is, afcrude petroleum from which the naturally contained gasoline and other light products have been distilled off according to well known refinery methods. Referring to the drawings, and at first more particularly to Fig. 1, the topped crude is charged into a primary vaporizing tank or still 10 through valved charging line 101. The vaporizer 10 is most desirably provided with a vapor dome 11. The va rizer in this particular instance is not itselixdirectly red, but is connected by intake and return pipes 12 and 13, respectively, to a direct red pipe still o r heater indicated generally at 14, the pipe coil 15 of said heater being connected as shown to pipes 12 and 13. The vaporizer 10 is most desirably provided withv eicient heat insulation I. In operation', the oiI is pumped from the lower part of the vaporizer 10 by pump 16 and is forced upwardly through pipe coil 15 in the heater, the heated oil passing thence back intogj? the vaporizer through pipe 12 and sprayy pipe 102 which is located above the normal liquid level in the vaporizer. Vapors evolved in the vaporizer pass oil through vapor of-take 17 to condenser coils 18, this condenser being most desirably so designed that it can be operated either aircooled, or cooled by water sprays 19, according to the prevailing atmospheric conditions. The distillation of the topped crude in the primary distilling system, of which the heater rocedure involves substantial 1 4 and the vaporizer 10 form parts, is conducted in such manner `as to distill over practically all of the crude that can be vaporized at substantially atmospheric pressure, the charge being usually run down to heavy residue, such as pitch or what' is commonly known 'asflux oil. It isA desirable, however, that the vapors going over to the condenser 18 shall be substantlally free of tarry materials. Vapors and condensate of this character can be readily obtained if the described primary distilling system is operated at a normal rate, that is, if it is not driven too hard. It is especially easy to attain this 'result if the vaporizer 10 be of such ample capacity that, when normally charged, there is a large vapor space in the upper part. of the vaporizer in addition to the dome 11. Under such circumstances no special precautions are'required in order to obtain a coni densa-te in 18 of the character desired.

The liquid condensate from 18 passes through the condensate line 20 tostorage tank 21 for cracker stock, and forms the supply or stock from which oil to be vaporized and passed into the cracking zone, hereinafter tobe more fully described, is drawn. The cracking `chamber is indicated generally at 22; and in the particular system illustrated cracked vapors pass therefrom into a heatexchanger 23 and thence into a dephlegmator 24 where they give up most of their superheat to liquid oil going to the cracker, as will presently appear. In carrying out the novel process'with this type of system, the oil to be vaporized is drawn by the pump 25 from cracker stock storage tank 21 and is pumped by way of line 26 through coil 261 (Fig, 2) disposed at an intermediate localit in the dephlegmator 24 before mentione through line 27 into the lower part of the intertubular space in heat exchanger 23, traveling upwardly around thevapor tubes 231 (Fig. 2) therein, and finally leaving the heat exchanger through line 28 and going to pipe coil 29l of a pipe heater or vaporizer 30 which may be similar in construction to the heater 14 before mentioned. A pipe still such as this provides a heated zone of restricted cross-section through which oil may .be 'passed at relativelyfhjgh -velocity while undergoing rapid increase in temperature. By passing the oil from 21 through the dephlegmator and heat exchanger as described,

' this oil is preheated bythe hot vapors coming from the cracking chamber 22 before being vaporized by passage through the heater pipe coil 29, whlle at the same time the cracked vapors lose their superheat andan undesirable heavy constituents are lique ed and separateiLThe supply of oil tosaid pipe coil-29 is so regulated by valve means (not shoyvnyin the 'pipe'.:that by the time the oil 'aches the top of the coil it is completely The firing of the heater 30 is so the heater have a temperature somewhat, but

not greatly, above the temperature at which it is desired to maintain the cracking zone. Inroperating on the type of oil referred to in this illustrative example, and where it is desired to maintain a cracking temperature of between 530 and 550 C. in the vapor phase cracking zone, it is good practice to so regulate the firing of the pipe 30 'and the supply of liquid oil thereto that the eiiluent vapors have a temperature of about 550 C. to 600 C., for example, at their point of exit from the heater. The superheated but largely uncracked oil vapors pass from the heater through line 31 into the upper part ofthe cracking or converting chamber 22 before mentioned. This converting chambermayf rial that is 5 or 6 feet thick in a typical instance and is supported on a false bottom or grating 221r formed of I-section bars. Said contact material is of the general character hereinabove referred to as desirable-for use in the process; and a good grade of pumice, in lumps vranging in diameter from 2 to 6 inches, has been found in practice to be ideal for the purposes in view, since it actively promotes the conversion of the heavy oil vapors into lower boiling products and at the same time is refractory or resistant to deterioration under the conditions of o eration, being chemically inert toward sul ur, nitrogen and carbon under said conditions. By inertness to carbon is to be understood the absence of tendency on the part of the contactmaterial to favor separtion of free carbon from the-vapors and building up of such free carbon in'coky layers on said contact material.

Where best operation of the present process is sought, the employment of the .usual metallic or metallized contact materials is not advisable. The cracking zone, including the mass of lump pumice, may have been previously brought up to cracking temperature in any suitable manner, but most desirably by passage of hot oil vapors into and through the cracking chamber, -the vapors thus used in the preliminary heating up usually going through unchanged or substantially so. After the desired cracking temperature has been thus attained, it is easil maintained within the desired operatiilg 'mits simply through continued passage of said hot oil vapors into the chamber in controlled quantity and atcontrolled temperature, without external heating. For best results, it is important' that not only thecracking chamber but also the associated heat exchanger and dephlegmator, together with the connecting piping including the pipes by which the preheating and cracking system is connected lto 5 the pipe still or heater 30, be heavily lagged with heat insulation I. This is not merely to economize heat, but is also to facilitate .attaining and maintaining the proper cracking temperature in the cracking zone, as well as to enable such temperature to be regulated and controlled with flexibility and accuracy by regulating the rate of vfiring of heater 30 and the rate of oil flow into and through the coil 29 therein.

In the cracking or converting chamber the oil vapors undergo a cracking or splitting up with production of a large proportion lof lower-boiling constituents on the one hand, and formation of some tarry and other heavy products, on the other, due to recombination of certain of the cracked products. There is, however, no sepa-ration of carbon that produces coky deposits and chokes up the converting zone; and in practice it is feasible to run continuously for weeks or even months at a time without once shutting down to clean out. Such heavy constituents of the cracked products as condense at the temperatures prevailing in the cracker collect in the drip space below the grating 221 and are disposed of in a manner to be described later. The persisting vapors pass down through the grating and thence upward through the central vapor oll'take A32 which opens below the grating, as shown. The mean temperature of the cracking zone mayT be observed by means of one or more suitable pyrometers` the thermo-couple of one being shown at 222 projecting into the mass of pumice a. little below its upper surface and extending substantially two-thirds of the distance from the cracking chamber wall to the central offtake 32. Suitably covered openings 223 are provided for charging contact material into the cracking chamber, and suitably covered openings 224 for removing such material when required. The base portion of the chamber is provided with lateral clean-out openings 225 and a central tar discharge 226, all suitably covered, as shown.

Bailling means or the like may be provided inside of the cracking chamber to compel the oil vapors to follow a predetermined course of travel through the chamber from the point of entrance to the point at which the cracked products make their exit through vapor line 32; but baffling means are not usually essential and are not used in the apparatus here illustrated. Vapor line 32 conducts the cracked vapors into the upper part ofJ heat exchanger 23, through the tubes 231 of which they pass downwardly and thence through vapor line 33 to dephlegmator 24 before mentioned. As the cracked vapors pass down through heat exchanger 23, some of the residual higher boiling products formed in the converting or cracking operation liquefy and drop out as a result of the reduction in temperature of the vapors, such higher boilin products refluxing through insulated an trapped drip line 34 and going back to the primary vaporizer 10, as will subsequently appear. In the present instance, this drip line 34 discharges into the drip space of the cracking chamber 22 in order that said heavier products may be utilized to wash or flush out of the bottom of the cracking chamber any higher boiling condensate collecting there as aforesaid, the combined material being drawn from the drip space of the cracker by pump 35 and .directed thereby-through line 36 to the vaporizer 10 as shown. The reason for returning this condensate to the vaporizer 10 and not to the cracker Stock storage tank 21 is because it contains tarry or tar-forming constituents which, if introduced with the oil vapors entering the cracking chamber, would cause carbonization and coking and thus choke up the system. Line 36 leaves the drip space somewhat below the level at which line 34 enters, in order that the entering portion of line 34 may always be kept drained.

As the vapors from line 33 pass u through the dephlegmator 24, a further quantity of residual relatively heavy constituents is condensed and drops out of the vapors by reason of the further cooling and also the washing ory dephlegmating action which the vapors experience in the dephlegmator. This further condensate which, though relatively heavy as compared to the desired final product, is nevertheless substantially free of tarry constituents, leaves the base of the dephlegmator through line 37 which conducts it back to the cracker stock storage tank 21, there to mingle with the condensate coming from 18, the mixture being vaporized in pipe coil 29 and cracked in the cracker 22 as before described.

The residual light vapors leaving the top of the dephlegmator A24 usually range in temperatures from 200 to 250o C. depending upon the desired character of the crude motor fuel condensate to be obtained therefrom.Y Said vapors go through'vapor line 38 to condenser 39 where a motor fuel condensate of the gasoline type is obtained. Said condensate passes by Way of line 40 to the receiving house 41 and thence througha look box 42 and line 43 to receiving tank 44. The light vapors and gases pass by way of line 45 to a gasometer 46. Light vapors and gases escaping condensation in the primary condenser 18 also go to gasometer 46 by way of vapor line 47 which enters line 45 beyond the receiving house.

In operating upon stripped or topped crude of the Corning grade,- for example,

and regulated as to maintain the temperture, observed at a point near the center of the mass of contact material in chamber 22, within a range of from 530 to 550 C., which is at present considered. an optimum range,

l it is ordinary practice with the present process toconvert from 70 to 80 per cent, or even more, of the stock taken from the topped crude starting material into @the motor fuel condensate that is collected in the receiving tank 44. This motor fuel condensate has the. following characteristics in typical instances.

Gravity (Baum) 45 to 50 Initial boiling point to 50 C. Dry end point 475 C. to 525 C. Color Yellowish -may also receive special treat` ent for vcan be regu elimination of resin-forming co stituents therefrom with production of a truly stable gasoline or motor spirit, by treatment with aluminum chlorid, zinc chlorid, or the like, in accordance with the methods described in copending applications filed by the present applicant: Serial No. 621,076, led February 24, 1923,; Serial No. 624,268. filed March 10, 1923; and Serial No? 672,438, filed November 2,1923.

The period-of exposure of the relatively heavy oil vapors to crackin conditions in chamber 22 should of course e of such duration as will eii'ect a satisfactory degree of conversion into the lighter products desired. -In any given instance, the length of the exposure period is dependent/upon the length of the vapor path through the mass of polrous contact material in the cracker cracking chamber, and upon the velocity of flow. For any .given cracker the exposure period lated and controlled by reguV-` lating and controlling the rateat which the heater 30 is fired, which alsol serves as la means of regulating the cracking tempera- 5s ture as already pointed out. Where the vapors pass through thelcrack'er at relatively high lvelocity, a relatively. high cracking vtemperature' can be used; while at low velocitiesof flow, the cracking temperatures should below. In any case, however, the velocity of' the vapors while' passing through the relatively, large-diameterl cracking chamber' is much less than :their velocity in pipe 31.

In -a typical' instance 'a' total charge of 14000 gallonsof topped Corning crude'is constituents, is not restric run down to heavy residuum in the primary heating and va rizing system 10-14 in about 48 hours. uring this same period the resultant liquid oil condensate collected in 21 is run through thevapor phase cracker vand a yield of motor fuel condensate, amountin to say 75 per cent by volume of the origina topped crude is collectedin tank 44. In this instance the cracker is a cylinder lled with Italian pumice in lum s ranging from 2 to 6 inches in size, the eective length of the path of the vapors through the pumice being e about 5 ori6 feet.

While `'pumice is especially recommended as a highl eiiicientporous adsorption contact material to 'use in practicing the invention, ityfisto be understood that other porous adsorp't efmater'ials having .the requisite characteristics of resistance to change Kand deteri'ration at the temperatures involved,

and "the necessary chemical inertness or inactivity-,ofthe nature hereinabove set forth, mayI/he employed instead of or in conjunction with pumice. Among such other materials may be 'mentioned various porous mineral substances comprising silicates, especially those containing compounds of aluminum; as well as silicic acid and oxids, particularly in amorphous and lcolloidal forms. Diatomaceous silica of high adsorptive properties and so-called silica gels are also ef fective.

In the specific illustrative example of the process described herein, operation at sub? stantially atmospheric pressure has been assumed. However, as pointed out in copendin'g applicationSerial No. 512,894 aforesaid, the vapor-phase cracking may be conducted under superatmospheric pressure within the sco e ofthe invention.

t is to be understood that the foregoing specic examples of are given merely for t e purpose of explaining the principles of the mvention by means of concrete operative embodiments thereof that have given satisfactory resultsV in actual rocess and apparatus practice; but that the invention is in no sense limited to the particular details of process and apparatus hereinabove given. It will be understood that the obtaining of oil vapors',v

for cracking, substantially/free from tarry involving the relimnary distilling and condensing step ereinabove described by way of exp anatory example, but that withinv the scope ofjtheinventionsuch oil va ors ma dtoaprocedure I. .i

bev obtained by heat-treating a mineral 011 'I 4, in any appropriate manner eiective for the Purpose. y What is claimed is:

1. The process of-oil conversionwhich" comprises establishing anoil'craeking'orconvertingzone, including a of porousadsorptive contact material, heated tofcrack-i ing temperature, passing oil "Pars-inw" i".

sa ot and through said mass, said vapors being supplied at such initial temperature and at such rate as to maintain said mass at cracking temperature substantirlly without other input of heat into said mass, and to effect substantial cracking of said vapors and separatin a desired conversion product of lower bolling point than the vapors introduced into. said cracking zone from the vapors leaving' said cracking zone.

2. The process of oil conversion which comprises heat-treating a mineral oil to ob- 1tain therefrom hot vapors largely uncracked and substantially free from tarry constituents, Passing said hot vapors through a mass o porous contact material substantially inert to sulfur, nitrogen and carbon, under the conditions of operation, at such rate and at lsuch initial temperature that said mass of contact material is maintained by the pasge of the hot vapors, substantially without er input of heat into said mass, at cracking or converting temperatures not higher than about 600 C. and substantial cracking of said oil vapors is effected and treating the resultant vapors to separate a motor fuel condensate therefrom.

3. The process of oil conversion which comprises heat-treating a mineral oil to obtain therefrom hot vapors largely uncracked and substantially free from tarry constituents and passing said hot vapors through a mass of porous contact material substantially inert to sulfur, nitrogen, and carbon, under the'conditions of operation, in such quantity and at such initial temperature that said mass of contact material is maintained by the passage of the hot vapors, substantially without ot er input of heat into said mass, at from about 490 to 575 C. and substantially cracking of said vapors is effected and treating the eluent vapors to separatev a motor fuel condensate therefrom.

4. The process of oil conversion which comprises heat-treating a mineral oil to obtain therefrom hot vapors substantially free from tarry constituents, and passing said hot vay pors through a mass of pumice at such rate and at such temperature as to maintain it, by such passage, at from about 530 to 550 G. and to effect substantial cracking of said vapors and treating the resultant vapors to separate a motor fuel condensate therefrom.

5. The process o f oil conversion which comprises distilling a topped crude petroleum and condensing from the distillate an' oil substantially free of tarry constituents, heating such condensed oil to vaporize the Same and passing the hot vapors into a cracking chamber insulated to minimize loss of heat therefrom and through a mass-of adsorptive contact material contained therein, the temperaturefwithin said chamber being maintained at cracking temperature not substantially eX- I'eeding 600 C. by such passage of vapors,

substantially without other input of heat into said chamber, and treating the vapors after passage through said chamber to separate a relatively light product therefrom.

6. The rocess set forth in claim 5 further characterized by the fact that the temperature in said cracking chamber is maintained at between about 490 and 575 C.

7. The rocess set forth in claim 5 further characterized by the fact that the temperature in said cracking chamber is maintained at between about 530 and 550 C., and that said contact material is pumice.

8. The process of oil conversion which comprises distilling a topped crude petroleum and condensing from the distillate an oil substantially free of tarry constituents, heating such condensed oil to vaporize the same and passing the hot vapors into a conversion chamber insulated to minimize loss of heat therefrom and through a mass of adsorptive contact material contained therein, the temperature within said chamber being maintained at cracking tem rature not substantially exceeding 600 by such passage of vapors, substantially without other input of heat into said chamber, utilizing the hot Vapors leaving said conversion chamber to preheat more of said condensed oil to be vaporized, collecting resultant heavy condensatel from said vapors and directing same into and through the lower part of said conversion chamber to aid in removing therefrom any heavy condensate collecting therein, and further treating said vapors to obtain a motor fuel condensate therefrom.

9. Apparatus for oil conversion comprising the combination, with an oil-supply contalner, a vaporizer, and conduit means connecting said container and vaporizer, a cracking chamber into which vapors pass from said vaporizer and having walls insulated to minimize transmission of heat therethrough, condenser means to which cracked vapors pass from said cracking chamber, and means, comprising a heat exchanger and a dephlegmator which are interposed between said cracking chamberand said condenser means and throu h which partof said' con-l duit means exten whereby said cracked vapors going to said condenser are brought into heat-transferring relation to the conduit means aforesaid.

i l0. Apparatus for oil conversion comprising the combination, with a primary. vaporizer, condenser means connected thereto, and a receiver to which condensate passes from said condenser means, of a second vaporizer, conduit means for. conducting liquid to said second vaporizer from said receiver, a cracking chamber into which vapors pass from said second vaporizer, a plurality of fractionating devices, arranged in series, through which cracked vaporsl pass successively after leaving said cracking chamber for separation in liquid form of relatively heavy con.

stituents therefrom, condenser means to which residual vapors pass from said frac tionating devices, conduit means for conducting to said primary vaporizer the heaviest portion of the constituents separated in said fractionating devices and conduit means for conducting to said receiver a less heavy portion of such separated constituents.

11. Apparatus for oil conversion as set forth in claim 10, further characterized by the fact that said fractionating devices comprise a heat exchanger and a dephlegmator through which the cracked vapors pass in the order named, a part of said conduit means between said receiver and said second vaporizer being in heat-receiving relation to the vapors passing through said heat exchanger and dephlegmator; and by the further fact that said conduit means comprise pipe lines conveying separated liquid from said heat exchanger to said primary vaporizer and from said dephlegmator to said receiver, 'respectively.

12. Apparatus for oil conversion, as set forth in claim 10, further characterized by the fact that said ractionating devices comprise a heat exchanger and a dephlegmator through which the cracked vapors pass in the order named, a part of said conduit means between said receiver and saidsecond vaporizer being in heat-receiving relation to the vapors passing through said heat exchanger and dephlegmator; by the fact that said conduit means comprise pipe lines conveying separated liquid from said heat exchanger to sald primary vaporizer and from said dehlegmator to said receiver, respectively ;and

y lthe further fact that the lower portion o said cracking chamber is interposed in the pipe line that conveys separated liquid from said heat exchanger to said primary vaporizer, whereby separated liquid trom said heat exchanger isutilized to aid in removing from said cracking chamber heavy liquid matter that may separate therein and in conducting same to said primary vaporizer.

13. The process of cracking mineral oil which comprises superheating mineral oil to a temperature above the crackin point but so rapidly that the oil! remains ar ely uncracked, then discharging vapors only of the superheated oil into a cracking chamber and maintaining them in said chamber at cracking temperature for a sulicient time and under such conditions that extensive cracking is elected, the temperature of the cracking chamber being maintained at the roper oint substantially only by the super eat o said vapors, and recoverin a relatively low-boiling condensate from t e vapors leaving said chamber.

14. The process of cracking mineralV oilv 'heating z'one into a cracking zone and allowing them to travel therethrough at materially lower velocity and for a length of timesui- Acient to effect extensive cracking, said cracking zone being maintained at cracking temperature substantially only by the superheat of the oil vapors supplied thereto, and recovering a relatively low-boiling condensate from the vapors leaving saidcracking zone. 15. The process of cracking mineral oil which comprises rapidly superheating mineral oil vapors to a temperature not substantially exceeding about 600 C., the time during which the vapors are subjected to cracking temperatures at this stage being so short that they remain largely uncracked, then discharging the superheated vapors into a cracking chamber maintained substantially only .by the super-heat of said vapors at a cracking temperature somewhat below the temperature of the entering vapors and allowing the vapors to remain' therein until substantial cracking has occurred, and recovering a relatively low-boiling condensate from the vapors leaving said chamber 16. The process set forth in claim 15, further characterized by the fact that in said cracking chamber the oil vapors are caused to contact with a porous adsor tive contact material adapted to favor crac ing,

, 17. The process of oil conversion which comprises passin vapors of a mineral oil through a mass 0% porous adsorptive contact material, said vapors being superheated sumf ciently to maintain the desired cracking reaction of the vapors when passed through said contact material, and to maintain said material at the required temperature for said reaction, and separating a condensate of the motor fuel type'from the resultant vapors.

In testimony whereof I hereunto aix my signature.

WILLIAM G. LEAMON.

which comprises conducting mineral oil as a i rapidly flowing stream through* a heating

Images