US1769788A - Process of and apparatus for treating oils - Google Patents

Description

July 1, 1930. w. G. LEAMON PROCESS OF AND APPARATUS FOR TREATING OILS Filed Nov. 4, 1921 Patented July I,- 1930 PATENT OFFICE WILLIAM G. LEAMCN, F NEWARK, OHIO PROCESS OF AND APPARATUS FOR TREATING OILS Application filed November 4, 1921.

This invention relates to processes of and apparatus for treating oils; and it relates more particularly to processes of and appa-.

. ratus for converting relatively heavy hydrocarbon or mineral oils into lighter products, especially gasolene or other products more or less closely allied to and resembling gasolene in properties, and often designated generally as motor fuel or motor spirits.

A principal object of the invention is'to provide a methodical and accurately controllable procedure for the treatment of mineral oils and residue of all kinds, whereby conversion into lighter products may be effected in an economical, efficient and continuous manner, without interruptions to working universally encountered in converting or cracking processes heretofore proposed occasioned by carbon deposition in the converting or cracking zone. 7

A further object of the invention is to enable so-called vapor-phase methods of oilconversion or cracking to be employed successfully on a practical scale, by eliminating the defects characterizing such methods as they have been heretofore proposed.

A further object of the invention is to provide an improved gasolene or motor fuel of novelcomposition and characteristics, said gasolene or motor fuel possessing superior qualities for power production and other valuable and useful properties.

Still another object of the invention is to provide apparatus especially well suited for practicing the process of the invention to best advantage.

With the foregoing general objects in view, as well as others which will become apparent as the description proceeds, the invention 40 comprises the process steps and combinations of steps, the novel compositons of matter, and

the features, details and combinations of ap-'.

paratus parts, which will first be set forth in the following description and then more particularly pointed out in the appended claims.

Serial No. 512,894.

Generally described, the process of the present invention involves decomposing, c0nverting or cracking an oil in a suitably heated converting zone to obtain lighter product-s therefrom, this being carried out under such carefully predetermined and accurately controlled operatlng conditions, Including regulation of temperature, composition of hydrocarbons entering the converting zone, rate of passage through said zone, etc., that no substantial deposition of carbon occurs in the converting or cracking zone, special provision being made to ensure that any deposition of carbon unavoidably incidental to conversion of aheavy oil into lighter products shall take place outside of the main converting or cracking zone under conditions in no wise interfering with the regular and continuous progress of the conversion process as a whole.

' The terms converting, decomposing and 65 cracking are used herein interchangeably, and each generic to the others, to designate broadly the molecular changes undergone by hydrocarbon oils generally when subjected to heat at a sufficiently high temperature to 7 cause breaking down, splitting or cleaving of'the molecules, with or without deposition of carbon, and with formation of at least some lighter products.

In order to afford a full understanding of 7 the invention, but without intending thereby to limit the invention to specific details hereinafter set forth, certain concrete examples embodying the principles of the invention in especially advantageous practical formwill so now be described by way of explanatory illustration.

Assume that the oil to be converted is a fuel oil, such as a stripped Kentucky crude, that is,

a Kentucky crude petroleum from which the gasolene and kerosene fractions have been distilled off by usual and well-known methods; and that it is desired to convert it into a commercial gasolene as faras possible. In carrying out the present process, this stripped crude is charged into a coking still of ordinary type, and the still is operated to run the charge to distillate and coke in the usual manner, save for certain exceptions to be noted hereinafter. principally to a systematic and carefully regulated return for further coking still distillation (whether in the same coking still or not is immaterial) of relatively high-boiling condensates obtained at various points in the apparatus system of which the coking still forms a part. The system includes a heated retort or chamber providing the main converting or cracking zone proper, into which, in the particular illustrative example hereinafter set forth only a definitely selected and gredetermined fraction of the coking still istillate is allowed to enter. In that chamber, the aforesaid selected fraction underoes cracking, most desirably in vapor phase. he vapors leaving the coking still may therefore be fractionated to separate and return thoseconstituents of which the vapors con dense above a certain temperature which, though capable of some variation in practice,

. may advantageously be taken as 350 to 360 C. or thereabouts. I have found that constituents condensing substantially above 350 to 360 C. should be prevented from entering the cracking chamber if deposition of carbon' therein and consequent choking of the apparatus are to be avoided.- It is to be understood that the temperatures herein referred to are measured in the vapor line and are not the temperatures of the liquid oil in the still. A

'liihter intermediate fraction or cut of the ing still distillate, condensing within a range of from around 175 to 350 or 360 C., and comprising in a typical instance, the heavy naphtha, kerosene and light gas oil, is separated and employed as the selected fraction to be fed .into the cracking retort or chamber. A still lighter fraction or cut, in cluding some commercial gasolene, casing head or com ressor gasolene and fixed gases,

may be con acted to a suitable condensing systemfor recovery of commercial light condensates. Where a stripped crude is being treated, as here assumed, this fraction of the coking still distillate is not large.

Moreover, the vapor products resulting from cracking the aforesaid intermediate dis- -tillate in the cracking retort are themselves separable into three cuts or fractions gener-' ally comparable in character and boiling range with those into which the coking still distillate is divided; and in practicing my novel process in its best form, the vapor products leaving the cracking retort are therefore fractionated in corresponding manner, the heaviest or highest boiling out being sent ba'ck for coking still re-distillation, and the intermediate cut returned for re-treatment in the cracking zone; while the third or gasolene-containing cut is sent to the con-- These exceptions relate denser for recovery by known methods. In

practicin the novel process, the hea or hi h-boihng cut or fraction of the crac ing tu e or retort vapors which is returned for coking still re-distillation and which results probably from s nthetic re-combination or polymerization 0 some of the cracking products, frequently runs approximately 15 to'20 per cent of the selected fraction fed to the cracking chamber; while the intermediate cut may be from 20 to 30 per cent of such selected fraction.

From the foregoing general outline of the novel process, it will be seen that it involves, among other things, treating the oil to be con verted in such manner that substantially only constituents boiling at or below a predetermined maximum temperature are introduced into the cracking zone, there to undergo vapor-phase cracking; while higher boiling constituents, including any such high-boiling products as are unavoidably formed in or as a result of the vapor-phase cracking, are subjected to what amounts to liquidphase cracking in a coking still or its equivalent. By this methodical separate treatment -of the heavy and intermediate cuts or fractions, car ried out in a cyclical manner as will appear more fully hereinafter, the whole of the original oil used as starting material can be converted into a useful commercial light distillate, such as gasolene, with formation of only relatively small percentages of coke or pitch and fixed gases as by-products. Moreover, where the vapor-phase cracking is properlyconducted in accordance with my invention, there is substantially no deposition of carbon in the'cracking chamber, practically all the free carbon separated in effecting the conversion of the entire starting oil appearing as coke or pitch in the coking still, from which it can be removed very easily as compared with por-phase crackin chamber or tube. Such contact material s ould most desirably be a silicon compound; and among silicon compounds particularly advantageous for present purposes may be mentioned oxygen compounds of silicon, such as silicates (especially of high silica content), and silicic acid and oxids, especially in amorphous and colloidal forms. Compounds of silicon containing aluminum offer important advantages; for example, an acid aluminum silicate mineral such as pumice stone gives extremely good results in practice. Among other compounds of silicon that can be employed as contact material may be mentioned 'sO-called sil-oeel, which is diatomaceous silica of high adsorptive properties, and colloidal forms such as so-called silica-gels of which the type disclosed in U. S. Patent No. 1,297,724 to Patrick is an example. Material of the character above described acts as an adsorptive contact agent and affords an enormously extended,

surfaceto aid in effecting the desired splitting or cleaving action, while at the same time it is substantially inert toward sulfur, nitrogen and carbon under the conditions of operation, its effectiveness as a cracking promoter therefore remaining unimpaired even after continued use over long periods of time. The use of such a contact agent and surface extender is of very great importance in the best embodiment of the invention, and

in conjunction with the other features characteristic of the invention herein emphasized,

it enables the attainment of results heretofore vainly sought in the art of oil conversion.- The term refractory as hereinabove applied to the contact material used is to be understood broadly as signifying substantial inertness or resistance to deterioration under the conditions obtaining in the vapor-converting zone.

It is to be understood that the process is susceptible of being operated continuously, and most desirably is so .0perated.- By employing two or more coking stills, any one of which may be cut out temporarily for cleaning and re-charging, a continuous sup- 7 ply of coking-still dstillate for the described over, the fraction of the cracking tube products that is returned to the cracking zone need not go to the identical tube in which it was produced. As such details are not required for an understanding of the essential features of the invention, the system of apparatus now to be described in further explanation of the invention is a simplified form embodying but one coking still and one cracking tube. It

is to be understood, therefore, that reference in the appended claims to returning heavy condensates 'to the coking still, and returning a fraction of the cracking products-through the cracking tube is to be interpreted in a broad sense consistent with the use of several coking stills, cracking tubes, etc. as above explained.

Referring to thev drawing which is more or less schematic or diagrammaticin charactor, a system of apparatus that has been found desirable in actual practice for carrying out the process of the invention is illustrated in side elevation, certain parts being shown broken away and in section. The apparatus system here illustrated comprises a coking still 10 and a converting or cracking tube 11, associated with fractionating and other condenser means, necessary connecting piping, etc. in a manner to be more fully hereinafter described. Assuming the system to be used for production of acommercial gasolene or other motor fuel from the stripped Kentucky crude previously referred to, the coking still 10, which may be of the wellknowncylindricaltype,mountedinbrickwork 12 and heated by any suitable burner means 13, is charged to about the level indicated at 14: by means of pump 15 from a supply reservoir 16. The coking still may be operated in the usualmanner; but with a fuel oil made by topping Kentucky crude, or oils of that general character, oil may be pumped into the still as it distills out to maintain a constant level for from 24 to 36 hours after distillation begins, but from then on the charge should be run to coke in the ordinary manner. The flue gases from the still furnace may be used, if desired, to preheat the oil added during the first part of the run. Where two coking stills are provided to run alternately and thus ensure continuous op eration of the system as a whole, the second still may be charged with preheated oil during the latter part of a run while the charge in the first still is being run down. A thermometer 17 may be provided for observation of temperatures in the coking still.

Through the vapor outlet 18 of the coking still, distillation vapors pass to fractional condensing means of a type suitable to enable return of heavy fractions to the coking still for re-distillation, and the separation of a lighter fraction suitable for introduction into the cracking retort or chamber 11, as above set forth. Such fractionating means may take various formsinprac'tice; but in the examplehere illustrated, it comprises a substantially vertical pipe 19 extending upward from a horizontal bend 20 to a second pipe 21 which is nearly horizontal but which is inclined slightly upward in a direction away from pipe 19. These pipe sections 19 and 21 are of fairly large diameter, 4-inch pipe being found suitable in practice; and they function substantially like dephlegmating towers, although in some respects they are more satisfactory than the so-called stone towers very commonly used as dephlegma tors. The pipe section 21, constituting the second section of the coking still fractionating condenser means may be cooled as de sired by water from the spray pipe 22, to

which water may be regulably supplied from any suitable source through valved manifold densed in 19 and trapped back into the coking still for re-distillation. In other words, in the illustrative embodiment of the invention herein described, the temperature of the vapors, observed at the bend between portions 19 and 21 of the vapor line, does not ordinarily much exceed about 350 to 360 C. As it is desirable to afford maximum opportunity for such trapped-back condensates to undergo liquid-phase cracking under the conditions of operation prevailing in the coking still, special means for attain? ing this object are here illustrated although such special means are not essential within the broad scope of the invention. As here shown, .the heavy condensates so trapped back are led by way of pipe 24 and check valve 25 into a coil 26 adjacent the bottom of the still, said coil discharging at 27 into the vapor space of the coking still. The pipe 24 is provided with a shut-off valve indicated at 28.

The arrangement" and operation of the fractional condenser means for the coking still is such that vapors condensing approximately at -or below 350 C. and above about 175 C. are condensed in the inclined pipe section 21. This fraction is the predetermined or selected fraction destined to be fed into the cracking or converting tube 11. Vapors escaping condensation in the pipe section 21, together with fixed gases, pass by way of vapor line 29, 30, to a condenser 31, the condensate obtained here, which should contain a useful motor fuel, passing by way of pipe 32 to a receiver 33. Uncondensed-vapors and fixed gases leave the upper section of condenser 31 through pipe 33*, and may be further treated if desired to obtain a compressor or casin -head gasolene; or if desired, the casin -hea ered by a sorption methods. In the present instance, the vapors and gases leaving constituents can be recov present instance the arrangement is such that the condensate can flow to the upper end of the cracking tube by gravity through pipe 40 which is shown looped at 41 to provide a trap, and which is provided with a check1o valve 42 and a hand valve 43, by means of which latter the feed of oil to the cracking tube can be accurately controlled and regulated in such manner as to maintain substantially constant temperature in the cracking zone. By handling the selected oil fractions in liquid form as here described, accurate regulation and control of the cracking zone temperature is greatly facilitated and is much simpler than if the oil were in vaposo rized condition. It is advantageous to preheat the oil before it enters the cracking tube and to this end the feed pipe is shown as passing through a heating jacket 44 which nace by which the cracking tube 11 is heated. In the present instance the cracking tube is shown mounted in brick-work 45 and heated by three gas burners 46, 47, 48 provided with may conveniently be simply a flue of the furregulating valves 49. The cracking tube 9 which may desirably consist of 10-inch to 12-inch iron pipe about 15 feet long, with about 10 feet of its length included between the furnace Walls, is desirably mounted with an inclination of about 3 to 5 degrees to the horizontal. The tube should be filled with a porous contact or catalytic material 50 of suitably refractory character, i. e. a material that is substantially inert or negative,

under the conditions of operation, with respect to sulfur, nitrogen and carbon. Various materials have been mentioned hereinbefore as suitable for this purpose. In practice I have found pumice stone an excellent contact agent and thoroughly satisfactory in actual ation. From my observations it a pears that the character of cracking induced y radiated heat differs very materially from that induced by conducted heat, in that in the former case the cracking is inevitably accompanied by copious deposition of carbon with its attendant disadvantages and evils, whereas in the present process, where heating by radiation is reduced to a minimum, cracking takes place with no appreciable carbon deposition. \Vhere pumice stone is used as the contact material it may be employed in lumps rangno ing in size from apples to hickory nuts. It should preferably be put in wire baskets from 3 to 4 feet long that fit the tube fairly closely.

This provision facilitates removing the pumice stone, which may become necessary after greatly prolonged operation, forthe purpose of cleaning out the tube or burning off the slight deposit of carbon that accumulates after very long continued running.

At 51, 52 and 53 are shown pyrometers by means of which the temperatures prevailing at different locations along the length of the cracking tube 11 can be observed, so that any necessary manipulation of the regulating valve 43 in the feed. pipe can be made to ensure maintenance of the proper cracking temperature. In practice, where the product sought is motor fuel, and where pumice is used as the adsorptive contact agent, the;

- burners 46', 47, 48 are'so regulated, and the feed of oil entering theupper end of the cracking tube 11 through pipe 40 is so controlled, that pyrometer 51, which is located in a portionpf the tube which precedes the cracking zone proper, indicates a tempera-- ture of about 400 to 425 C.; while pyrometers 52 and 53, which are located in the cracking zone proper, both indicate a temperature lying between about 540 and 565 C., the optimum temperature being approximately 550 C.- These temperatures are taken at about the longitudinal axis of the cracking tube, the thermo-elements of the pyrometers being embedded in the lumps of pumice .stone at about the axis of the tube. Practical experience with this method extending over a considerable period shows that where motor fuel is to be made, and where apparatus is used corresponding to the specifications hereinabove given, the optimum temperature of 550- G. in the cracking zone,

' cannot be greatly departed-from without a marked diminution in the yield of gasolene and a lowering of its quality; and that if temperatures are used materially outside the range above given, the resultsare practically negative. It is to be understood, however, that while this approximate temperature range is at present considered best, the figures given may vary somewhat especially where forms of apparatus are used differing in dimensions and arrangement from the apparatus herein specifically described byway of example. Ordinarily, however, the cracking temperatures used in practicing the in-- vention are not materially lower than 500 C. and should not materially exceed 565 0.,

600 C. being an upper limit which, according' to practical experience thus-far with the novel process, is materially higher than is consistent with attainment of best results. The oil fed into the upper end of the cracking tube 11 through pipe 40. is quickly vaporized, in the upper or first quarter or third of the tube, and then undergoes vapor-phase operation,-and it must be carefully taken into account in carrying out the present process.

According to my observations, best results are obtained when the time required for a given quantity of oil to pass through that portion of the tube included between the furnace walls 45 is about 20 seconds; and at present I regard a range of from 10 to 50 seconds as approximately defining the permissible time limits yielding practically useful results in carrying out the process of the invention with apparatus generally com-' parable to that herein described by way of illustration. c

From the lower or exit end of the inclined cracking retort 11 lead a vapor off-take 54 and a tar runback 55, this latter conveying any liquid tarry material that may collect in the lower end of the cracking tube into the bodyof oil contained in the coking still 10. The vapor off-take goes to fractionating means of any suitable character, such fractionating means consisting in the present instance of a long slightly upwardly inclined pipe 56, which may be of the same diameter as pipes 19, 21, and which like them functions in a manner similar to a dephlegmating Y tower. The fractionator 56 may be cooled by valved manifold 23.; The function of this fractionator is to separate the vapor productscoming from the cracking tube 11 into three fractions, namely, a first fraction consisting of relatively high boiling constituents inevitably produced in the cracking operation as a result of synthesis or re-com; 5 bination of split molecules, and consisting v chiefly of constituents of materially higher boiling point than the fraction mtroducedinto the cracking tube through the feed pipe 40; second, a lighter fraction of lower averno age boiling point, corresponding in fact to the fraction fedinto the cracking retort through the'p'ipe 40, and therefore suitable to be returned directly to the cracking tube for re-treatment; and third, a still lighter fraction that can be condensed to give a usable gasolene. Accordingly, the fractionator or dephlegmator 56 is provided near its lower end with a drain pipe 58 by WhlCll the first mentioned relatively very heavy fraction of the cracking tube vapors is conveyed to pipe 19 and thence through pipe 24 to the of oil undergoing distillation in the coking still. Said fractionator 56 1s also provided with a second drain pipe 59, here shown as-issuing from pipe 56 at a point somewhat more than half way from its lower end, this drain pipe 59 servmg to conduct the second or intermediate fraction intothe tor, where said intermediate fraction passes, to ether with the selected fraction of the co g still distillate, through'pipe, 40 to the upper end of the cracking tube 11. The remaining or third fraction, in the form of uncondensed vapors, passes through pipe 30 (into which pipe 29 also discharges) to the condenser 31, the gasolene or motor fuel condensate being received at 33, and any uncondensed vapors leaving the condenser 31 being further treated if desired as already deproduct sought, the temperature indicated by the pyrometers or thermometers and 61 is about 175 C. or thereabouts. w In practice I have found that in employing the described apparatus to treat a stripped Kentucky crude or similar oil for production of gasolene, most satisfactory results are obtained when the average rate at which'the selected fraction is fed to the cracking tube is about V to gallon per minute, the burners under the tube being turned onfull enough to ensure ample heating, and the cracking temperature being maintained substantially constant at 550 (J. by such occasional slight manipulation of the regulating valve 43 as the pyrometers may indicate to be necessary.

The gasolene obtainable by my novel process is of excellent quality and efliciency for motor fuel urposes. It may be used as condensed, wit out decolorizing or other refining treatment; ,orit may optionally be filtered through fullers earth or other decolorizer to removethe slight yellowish tin e characterizing the untreated condensate. It is distinguishable in its composition from gasolene eretofore known, but is not claimed in the prese t application.

A noteworthy fact. in-connection' with the invention is that the'character of the gasolene or othercommercial distillate'obtained gardless of whether the starting oil be a paraiiin base oil, an asphaltic base oil, or a mixed base oil.

In atypical instance, theyield of gasolene or other light commercial distillate is from r cent by volume of the original oil treate the coke is from 4 to, 6 per cent by weight; and the balance is so-called fixed ases. 1 i

Althoughthe' process has been described more particularly as applied to'produetion l 1 In practicing my process,

proportion of the so-called fixed of gasolene or a similar motor fuel, it is not to be inferred that the invention is limited thereto. For example, where conditions make it desirable to produce a naphtha for blending with casing-head gasolene, such naphtha may be produced in substantially the same manner already described 'for gasolene, save that the temperature in the vaporphase cracking zone should bemaintained somewhat lower, say at about 535 C., using the apparatus hereinabove specifically described.

It is to be noted also that the process is not limited to treating what are commonly comprehended within the term heavy oils. For example, the process may be applied with great success to gas oil, kerosene, etc. In the case of gas oil or kerosene, practically the whole of the distillate from the coking still overa considerableperiod passes to the cracking chamber,and it is not until heavy polymerized cracked products coming from the cracking chamber have accumulated in the coking still that substantial fractionation of the coking still distillate begins.

While in the foregoing description of one desirable specific way of practicing the invention, fractionation of the primary or coking still vapors has been referred to as a way of preventing entry of undesirably highboiling constituents into the vapor cracking or converting zone, it is nevertheless to be understood that any other suitable method of accomplishing this result may be employed within the broad scope of the invention as, for example, operating the primary or coking ,still at such rate that the undesirably heavy constituents aforesaid are not carried over with the vapors which it is desired to treat in the converting zone,

, Inthe specific illustrative example of the process described above at length, operation at substantially atmospheric pressure was assumed. The vapor-phase cracking may be conducted under, superatmospheric pressure, however, with the advantageous effect of proportionately increasing the output capacity of the plant. The use of pressures in the cracking tubes up to at least 5 or 6 atmospheres does not materially affect the other operating conditions .described. It is desirable to operate the coking still at sub- .stantially atmospheric pressure, however,

whether or not superatmospheric pressure is used in the cracking tubes.

I may return to the-'vapor-phase cracking zone any desired mg the final condensing system. uch a step tends in some degree to reduce the amount of fixed gases produced in cracking and to correspondingly increase the gasolene yield,

ases leavso that this expedient may sometimes be employed to advantage;

What I claim is:

1. The process of treating oil to obtain lighter products therefrom which comprises heating a body of oil-to distil vapors 4 5 therefrom, fractionating the distillate and returning that portion thereof condensing at and above substantially 360 C. to said body of oil for further heating, and cracking the lower boiling portion of said distillate. V

2. The process of treating oil to obtain lighter products therefrom which comprises heating a body ofoil to distil vapors therefrom, fractionating the distillate and returning the higher boiling portion thereof to said body of oil for further heating, and' cracking a lower boiling portion of said distillate in vapor phase, substantially all the constituents of said lower boiling por tion condensing within the approximate range of175 to-360 C. 3. The process of treating oilto obtain lighter products therefrom which comprises heating a body of oil to distil vapors therefrom, fractionating the distillate and returning the higher boiling portion there of to said body of oil for further heating, and cracking the lower boiling portion of said distillate in vapor phase and in contact with a mass of contact material substantially inert toward sulfur, nitrogen and carbon under the conditions of operation.

4. The process of treating oil to obtain lighter products therefrom which comprises heating a body of oil to distil vapors there from, fractionating the distillate and returning the higher boiling portion thereof to said body of oil for further heating, and cracking the lower boiling portion of said distillate in vapor phase and in contact with a mass of contact material heated to from about 540 to 565 0., said contact material being substantially inert toward sulfur, nitrogen and carbon under the conditions of operation,

5. Thej'process of treating oil to obtain lighter products therefrom which com prises distilling mineral oil in a coking still, separating and returning tofsaidstill the more readily condensible portion of said distillate, and cracking a less readily condensible portion of said distillate, substantially all the constituents of such latter portioncondensing within the approximate range of 175 to360 C.

6. The process of converting relatively heavy mineral oil intov lighter products whlch comprises distilling such mineral oil in a coking still, fractionating the distillate and returning a heavy portion thereof to the still, subjecting a. lighter portion of said distillate to a. decomposing temperature, substantially all the constituents of such latter portion condensing within the approximate range of 17 5 to 360 C., and collecting prodnets of decomposition.

7. The process of converting relatively heavy mineral oil into lighter products which comprises distilling such mineral oil in a coking still, fractionating the distillate and returning a heavy portion thereof to the still, subjecting a lighter portion of said distillate to a decomposing temperature, substantially all the constituents of such latter portion condensing within the approximate range of 17 5 to 360 C. and collecting products of decomposition, the dis tillation in said still being carried to pitch or coke.

8. The process of converting an oil into lighter products which comprises distilling a body of oil to heavy residue while continuously returning thereto heavier portions of the distillate, subjecting lighter portions of said distillate condensing between about 175 and 360 C. .to cracking temperatures ina cracking chamber, leading tarry products from said chamber to said bodyof oil under-' going distillation, and leading away and condensing vaporous products from said cracking chamber.

9. The process of converting an oil into lighter products which comprises distilling a body of oil to pitch or coke while continuously returning thereto heavier portions of the distillate, subjecting lighter portions of said distillate to cracking temperatures in a.

cracking chamber, leading tarry products from said chamber to said body of oil undergoing distillation, leading away 'vaporous products from said cracking chamber, fractionally condensing said vaporous products and conducting a resultant kerosene-contains ing fraction to said cracking chamber for vcrackmg treatment therein.

10. The process of converting an oil into lighter products which comprises distilling a body of oil to pitch or coke while continuously returningthereto heavier portions of the -distillate, subjecting lighter portions of said distillate to cracking temperatures in a cracking chamber, leading tarry decomposition products from said chamber to said body of oil undergoing distillation, leading away vaporous products from. said cracking chamber, fractionally condensing said vaporous products, conducting a relatively heavy portion of said products to said body of oil unclergoing distillation, conducting a second and lighter portion to said cracking chamber for cracking'treatment therein, and recovering athird and still lighter portion as a commercial condensate. I r

11. The process of oil conversion which comprises distilling oil, condensing a resultant distillate and conducting the liquid distillate into a vaporizing and decomposing chamber containing porous non-metallic contact material heated to cracking temperatures, condensing vapors leaving said chambar to obtain a commercial light condensate, and controlling the temperature range in said chamber by regulating the rate at which said liquid distillate is supplied thereto.

12. The rocess of oil conversion which comprises distilling oil in coking still means, fractionating the resultant vapors to condense and return to said still means a highboiling fraction, and to condense separately 11, lower boilin fraction, continuously feeding said lower oiling fraction in liquid condition through a regulating valve into aheated vaporizing and cracking retort containing an adsorptive non-metallic filling material of the pumice type wherein said lower boiling fraction is vaporized, maintaining the cracking temperature substantially constant by regulating the rate of feed of said lower boiling fraction to the retort, and treating the resultant products of cracking to obtain a valuable light fraction therefrom,

13. The process of oil conversion which comprises distilling oil, fractionally condensing resultant distillation vapors, returning a heavy fraction for re-distillation', feeding a lighter fraction to a vaporizing and cracking chamber filled with porous contact material of the pumice type heated to crack ing temperature, maintaining said crackingtemperature substantially constant by regulating the rate of feed to said vaporizing and cracking chamber, fractionally condensing the vapors issuing from said cracking chamber to separate a heavy fraction and a lighter fraction containing kerosene, returning said heavy fraction for re-distillation to produce further distillate for use in said cracking chamber, re-passing said lighter fraction containing kerosene through said cracking chamber, and condensing a still lighter fraction from the vapors escaping theaforesaid fractional condensation.

14. The process of oil conversion which comprises distilling oil in coking still means, fractionating the distillate to obtain a cut comprising approximately heavy naphtha, kerosene and light gas oil, while returning a heavier fraction to said coking still means, subjecting said out to vapor-phase cracking, fractionating the products of cracking into a heavy cut, an intermediate cut, and a light out, returning the heavy cut to. said coking still means, subjecting said intermediate cut to vapor-phase cracking, and collecting a motor fuel condensate from said light cut.

15. The process of oil conversion which comprises maintaining an oil-distilling zone and an oil vapor-phase cracking zone, fractionating the distillate from said distilling zone into a'heavy portion and a lighter portion, subjecting said lighter portion to' vaporphase cracking in said cracking zone, fractionating the roductsr of cracking into heavy, intermediate, and light cuts,'c0n'dli1cting theheavy cut to said distilling zone returning the intermediate cut to said cracking zone, and obtaining a commercial distillate from said light out.

16. The process of oil conversion which comprises cracking oil in vapor-phase in a tain another lighter fraction heavier than gasolene, and subjecting both said lighter fractions to vapor-phase cracking.

17. The process of oil conversion which comprises cracking oil in vapor phase, fractionating the products of cracking to obtain a light fraction, a heavier second fraction substantially free of constituents condensing above about 350 to 360 (3., and a still heavier third fraction, re-treating saidsecond fraction in vapor phase at cracking. temperature, subjecting said third fraction to further heat treatment in liquid phase, lobtaining therefrom a product suitable ,for vapor-phase cracking, and cracking such product in vapor phase.

18. The process of oil conversion which comprises cracking oil .in vapor phase in contact with'non-metallic adsorptive refractory material, fractionating the products of cracking to obtain a light fraction, a heavier second fraction substantially free of constituents condensing aboveabout 350 to 36090., and a still heavier third fraction, re-treating said second fraction in vapor phase at cracking temperature, subjecting said third fraction to further heat treatment in liquid phase,

obtaining therefrom a product suitable for vapor-phase cracking, and crackingsuch product in vapor phase.

19. The process of oil conversion which comprises distilling a body of oil to heavy residue, subjecting the distillate to heat at cracking temperatures not much exceeding 600" C. in a cracking chamber substantially filled with porous contact material substantially inert to sulfur and nitrogen under the conditions of operation, leading tarry prod ucts from said chamber to said body of oil undergoing distillation, and leading away and condensing vaporous products from said cracking chamber. f

20. The rocess of oil conversion which comprises istilling a body of oil to heavy .residue, subjecting the distillate toheat at cracking-temperatures in a cracking chamber substantially filled with porous contact material substantially inert to sulfur and nitrogen under the conditions of operation, lead ing tarry productsfrom said chamber to said body of oil undergoing distillation, leading away and fractionally condensingyaporous temperature included products from said cracking chamber to obtain light, intermediate, and heavy fractions, conducting the intermediate fraction to said cracking chamber for re-treatment therein, and conducting the heavy fraction back to said body ofoil undergoing distillation.

. 21. The process of manufacturing motor fuel fromrelatively heavy mineral oil hydrocarbons which comprises maintaining a suitable converting chamber substantially filled with porous adsorptive contact material at a about 500 to 600 0., supplying to said chamber relatively heavy mineral oil hydrocarbons in vapor phase, substantially free of tarry constituents, and allowing the vapors to remain in said chamber until conversion into lighter productshas occurred to a substantial obtain therefrom in combination,

extent, said contact tially inert toward sulfur, nitrogen and carbon under the conditions of operation, and treating the resultant vaporous products to a motor fuel condensate;

22. Apparatus still means cracking retort means associated therewith and containing adsorptive contact material substantially in ert to sulfur, nitrogen and carbon, fractionating means operating on the still distillate and arranged to return a high-boiling out therefrom, to said still means and to allow a lower boiling cut 'to pass to said "cracking retort means, and means for regulating the paswithin the range .of

material being substan-,

taining non-metallic adsorptive contact material of the pumice type, fractionating means operatm upon the products issuing from said cra 'ng retort means to separate therefrom a fraction heavier than gasolene but substantially free of constituents 'boihng above about 350 to 360 (3., and a second fraction that is heavier, means for returning the first fraction to said cracking retort.

means, and still means to which the second fraction '18 conveyed for distillation.

In testimony whereof. I hereunto aflix my signature.

WILLIAM G. LEAMON.

for treating oil comprising,

sage of such lower boiling. cut to said rotort C; to about 350 or means constituents con- 360 0., means for acurately controlling the rate of feed of the last named cut to said cracking retort means, fractionating means operatin upon the products lssuing from said crac 'ng retort cans to condense for return to said still means a cut containing the constituents condensing above about 350 to 360 C., and to separately condense for reintroduction into said retort means a second cut condensin from about 175 C. to about 350 to 360 and a condensing system arranged to receive uncondensed vapors and gases from-said fractionating means. Y :24. Apparatus for treating 011 compris ng, in combination, cracking retort means 0011-

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