US2093473A - Method and apparatus for treating hydrocarbon oils for subsequent cracking - Google Patents

Description

E. A. OCON METHOD AND APPARATUS FOR TREAIING HYDROCARBON OILS FOR SUBSEQUENT CRACKING I/.z J

ATTORNEY.

Patented sept. 21, i937 UNITED STATES PATENT METHOD AND APPARATUS'FOR. TREATING HYDROCARBON OILS FOR SUBSEQUENT CRACKING 19 Claims.

This application is a continuationin part of my application led August 3, 1935,`Serial No. 34,563.

The object of this invention is to provide a i novel method and apparatus to produce low boiling point products, suitable as motor fuel, by treating in a primary blending, Vaporizing and fractionating tower, with the aid of highly heated cracked hydrocarbon-products and steam passed into said tower, one or a plurality of streams of hydrocarbon materials .ofhighboilingpoint which may be preheated, such as crude oil, topped crude oil, liquefied coal, shale oil and allied hydrocarbons, to form from the vaporized and unvaporized hydrocarbons in said tower, two streams of puri.- ed substantially uncracked hydrocarbon fractions, each of different composition and characteristics and being adapted for subsequent cracking, the vaporized uncracked fractions of the charging stock higher boiling than gasolineblend- `ed with the cracked hydrocarbon vapors higher boiling than gasoline of the highly heated hydrocarbon products are. condensed, forming one stream, and the unvaporiz'ed portion of the uncracked charging stock mixed with entrained liquid of the cracked products forming the second stream, each stream being led toaseparatecracking zone and subjected preferably to different racking reactions under conditions of temperature and pressure most ecient tothecompositivon and characteristics of each stream for maximum conversion into low boiling point products, with the minimum formation of gas and almost complete absence of coke formation.

Another important object of. my invention is to provide a composite method for producing a novel sulfur treated synthetic hydrocarbon recycling stock consisting of a. mixture of heavy fractions of different composition and characteristics, namely condensed heavy uncracked fractions from the substantially vaporizedinitial charging stock, condensed heavy fractions from the hydrocarbons heated under low pressure to a mild cracking temperatureof about 850 F., and condensed heavy fractions from the hydrocarbons heated in a separate heating zone, u nder substantially higher pressure, to a higher cracking temperature. of about 1050 F. as hereinafter described. The invention further provides a method in- .which the heavy residue, including tarry and solid materials, is dropped from a zone in'the separationt'ower maintained in a. highly heated condition,- preferably gabove '750 a cooling material being continuously Ipassed into contact with said heavy residuesas 'they drop to the base of said heated zone for the reduction of temperature therein to avoid the formation of carbon.

The invention will be described with reference to the accompanying drawing in which I indiycates a pipe through which charging stock is passed to the preheaters 2 and 3 and thence discharged below the midsection of primary frac- Ytionating tower d. Into the fractionating tower l is discharged through pipe 5 controlled byvvalve 6' a suitable quantity of highly heated vapors which may be steam, and ammonia can also be carried by the steam, if desired, and into tower li may also be injected highly heated cracked hydrocarbon vapors passed into the tower through pipe l controlled by valve pipe l leading from the discharge`endof a cracking coil indicated at 9 and disposed `within the convection and "radiant lsections of a furnace lll, the convection section being separated from the radiant section lll by a wall indicated by dotted lines l2.y Y

By the preheaters 2 and 3 or byv any other suitable means the charging stock may be raised to a temperature of 50o-700 F. so that when the now of charging stock contacts with the highly heated vapors the unvaporized portion is raised in temperature and theI greater portion of its lower boiling point fractions are released as vapor without cracking although they may reach an incipient cracking^ temperature. therefore rises in tower El. and meets a cooling material injectedthrough pipe it from the straight run or light fraction tank It from which liquid may be withdrawn by a pump l5. In this manner the straight run gasoline and any cracked gasoline resulting from condensation of theheavy fractions of the products injected through pipes l and 'l will be carried to the tank it via pipe i6 and condenser Il from the top of the tower 4 and repassed by pump l5 to the interior of the' tower for the purpose stated. The heavy fractions that are condensed by the said cooling material are collected in a pan da: being then passed through pipe I8 by pump I 8a: part to a blending, chamber 2U and part to the ,upper section of separating tower 30. That portion of the charging stock which is unvaporized in tower l will fall to the base thereof and will be withdrawn through pipe 2l by pump 22 and passed to a second cracking coil 23. Sulfur absorbent material such as triethanolamine, ethylenediamine, sodium plumbite, lead acetate and the like, one or a mixture of two or more, preferably mixed with materials such as The `vapor alcohol, ether, water and gasoline or other suitable material, may be contained in a tank 2`4 and passed into tower 4 below the pan 4a: by means of a pump 24m to lower the sulfur content of the oil. Tower 4 has at the base thereof a valve controlled drain pipe 25 to discharge sludge. The unvaporized portion of the charging stock is then cracked in the lower temperature coil 23 of the furnace and is heated to a temperature, say from G-900 F. and is discharged into blending chamber 20 simultaneously with vthe products cracked in the coil 9 of higher heat. I

Coil 9 receives via pipe 26 and branch pipe 21 controlled by pump 28 the purilied composite heavy condensate of the second fractionating tower 29 and consisting of the heavy cracked lfractions higher boiling than gasoline range obtained from coil 23, 4and the heavy condensate higher boilingthan gasoline range of the intermediate uncracked fractions delivered to blending chamber 20 from pan 4m, and blended with the cracked products of the two coils. The composite condensate passed through coil 9 is heated to a lcracking temperature of say, 1000-1100 F. and the blended productsvfrom both coils pass from blending chamber 20 to a separation tower 30 and meeting the uncracked condensate from pan 4x of the primary fractionating tower 4. The blending chamber will discharge directly into a pan indicated at 30a: in which zone high turbulency is formed, and a temperature of 70D-800 F., more or less, is maintained. As the pan lls to its top, the fuel oil constituent, tarry material and carbon will overflow, as indicated by the arrows, and will then drop to the base of the separation tower. The vapors rise and meet a reiiux consisting of part of the intermediate uncracked fractions from the primary fractionating tower 4 passing through pipe I8 controlled by valves I9, |916, and a portion of the unvaporized oil of the primary .fractionating tower 4 passing from pipe 2I through a branch pipe 34 discharging into the tower near the top thereof and into the towerI through branch pipe 3Icc, if the' latter is desired. Ordinarily, pipe 3I may be eliminated.

Water or saturated steam and ammonia may be passed into tower 30 by means of valve control pipe 32. To cool the bottom of tower 30 a constant level of fuel oil may be maintained therein, as by constantly withdrawing the fuel oil through valve control pipe 33 by pump 34, cooling said fuel, returning the required proportion to tower 30 by valve control pipe'35 and passing the balance not needed to maintain the level to a cooler 36 via pipe 31 and thence to storage. 'I'he withdrawal member in tower -30 for the fuel oil pass'- ingto pipe 33 may consist of a perforated tube 38. 'I'he dotted lines at 39 indicate appropriate levels of fuel oil maintained in tower 30. At the base of tower 30 is a valve control draw-off pipe 25x for withdrawal of carbon and sludge from time to time, as required.

The lighter fractions pass from tower 30, preferably through catalytic material indicated at 49, and thence to secondary fractionating tower 29, this passage being through pipe 4-I.

As a regulator for the temperature of the vapors in fractionating tower 29, steam maybe infrom pipe 27 into branch pipe 43, the hot vapors exchanging heat to the incoming charging stock and thence passing into tower 29 through valve control pipe 44. Gasoline reflux may be passed into the top of tower 29 through valve control pipe 45 from tank 46 through the action of pump 4'I.` The tank 46 receives gasoline-type fractions from condenser 48 receiving gasoline vapors from pipe 49 communicating with the interior of tower 29 at the top thereof and the hot vapors may exchange heat at heat exchange 2, transferring the same to the charging stock passing through pipe I.

When it is desired to re-form the gasoline comprising the straight run and cracked gasoline fractions separated in fractionating tower 4, pump I5 may be employed to pass such mixed gasoline through pipe 50 to pipe 26, where the gasoline will meet the heavy condensate of secondary fractionating tower 29 and the gasoline will be re-formed during the cracking of said condensate within coil 9.

As an example of operation of the process, into the primary fractionating tower there is passed a regulated stream of uncracked hydrocarbon such as crude oil or topped crude heated, for example, to 700 F. and thereby substantially vaporized and raised in temperature therein by means of a blast of highly heated previously cracked hydrocarbon products admixed with water vapor passed into said tower, and having a temperature above 800 F., preferably 1000-1100 F., which serve a three-fold purpose; first, reduce the Viscosity of the crude charging stock; second, increase the de-4 lease therefrom the greatest portion of lower boiling point fractions without active cracking; third, increase the anti-knock value of the straight run gasoline separated by cooling from the vaporized heavy fractions of the charging stock by blending it with the cracked gasoline of the blast of highly heated vcracked products, and then condensing said gasoline blend, 'separately condensingwithin said primary tower the heavy uncracked fractions and revaporizing and mixing the same for mutual condensation with the cracked products resulting from heating, under a pressure rang'ebetween 5 and 25 atmospheres, the unvaporized fractions of the stock to a mild cracking temperature of from 800 to 900 F., separately cracking, under a pressure range between I5 and 60 atmospheres, said mixture of condensed uncracked and cracked fractions condensed in the second fractionating tower, lblending the resulting products of the two cracking zones, separating the residue and subjecting the blended vapors to fractionation and condensation.

As another qexample of the process, into the primary fractionating tower 4 there is passed a regulated stream of uncracked charging stocksuch as crude or topped crude oil which may be preheated, and in the tower the preheated charging Istock is raised in temperature by means of a regucreasing the degree of vaporization of the un-v cracked stock. lThis enables release therefrom of the greatest portion of the less volatile constituents'of the charging stock, the thus released straight runA gasoline fractions joining the cracked gasoline from the blast of cracked products. The vapors released above gasoline range are separated, by cooling, from the mixed gasoline fractions and condensed, and separately condensing the said gasoline fractions. The unvaporized fractions of the charging stock and entrained liquid of the blast of cracked products are collected at the lower end of the primary tower 4 and are carried to the cracking coil 23 receiving the lower temperature and therein heated undera pressure range of between .5 and25 atmospheresto a cracking temperature of approximately 850 F.

The resultingcracked products are blended with the uncracked heavy condensed fractions passed from the pan 4x to the blending chamber 29 and separating tower 30. 'I'he mixture of cracked and uncracked heavy fractions above gasoline range collected in the secondary fractionating `tower 29 are separately heated in a coil receiving the higher temperature, to wit, member 9, to a cracking temperature of approximately 1050 F., under `pressure range between 15 and 60 atmospheres, and the resulting products are'in turn 20 mixed in the blending chamber with the cracked 30 approximately at 1050 F., heavy fractions from the products cracked at 850 F., approximately, and heavy uncracked fractions from the heavy uncracked condensate from pan, 4x) are condensed and dropped to the base of tower 29 to 35 form a continuous stream of recycling stock for passage through pipe 21 and branch pipe 26 to said coil 9.

Sulfur reagent materials may be passed into the blending chamber 20 through valve' control pipe 5I from any suitable source. pass into superheater 52 through pipe 52a: and part led to the coil 23 via valve control pipe 53, an-d part of the steamfled to coil 9 via valve control pipe 54.

Instruments such as thermowells, temperature controllers and recorders, etc., are not indicated or mentioned, but it is to be understood that they will be used as required, as is well known in the art.

It will be noted that in passing the heavy residues from` the base of tower 30 and thence back thereto in order that both cooling and a constant level may be obtained, cooling may be veffected by passing the said heavy condensate through a heat exchange member 33a: with which pipe 33 will communicate. In that case, Water and ammonia will enter pipe 32 and the water may be raised up to saturated steam degree by the heat exchange member for discharge into the separating tower 30. l

Although the herebefore described method is preferred, the system of operation may vary considerably as there are characteristics in structure and apparatus which make myinvention one of broad application, and it is to be understood that modification and changes may be made provided they do not depart from the scope of the invention of the following claims covering the invention.

Having described my invention, what I claim and desire to secure by Letters-Patent, is as follOWS f Steam mayvaporization in a primary fractionating zone through the aid of highly heated vapors from a heating zone passed into contact therewith, separating and condensing in said zone the uncracked virgin gas oil fractions of said uncracked charging stock from the gasoline range fractions, withdrawing said gasoline fractions from the fractionating zone, withdrawing the unvaporized thus treated heavy fractions of the charging stock from the zone and heating the same under superatmospheric pressure to a cracking temperature of from 800 to 900 F., approximately, for a period suicient to produce substantial cracking, discharging the cracked products into a blending and separating zone,separating thereby the residue and tarry material, leading the uncracked virgin gas oil of the charging stock to the blending and separating zone and vaporizng it by mixing with the cracked vapors therein, passing the cracked and uncracked mixed hydrocarbon vapors into a secondary fractionating zone, separating and withdrawing from said secondary fractionating zone the gasoline-range fractions and condensing therein the fractions boiling at temperatures above the gasoline range,

and comprises gas oil fractions of the charging Vstock and the cracked heavy fractions of the crackedyapors, cracking said mixed condensed fractions under a higher cracking temperature than applied in the first-named cracking operation of the unvaporized charging stock and blend- -ing the resulting cracked products in said blending and separating zone.

2. A process for forming'a synthetic hydrocarbon product comprising a mixture of anuncracked vapor condensate boiling at temperatures above the' gasoline boiling point range ofan uncracked hydrocarbon charging stock, and a heavy cracked condensate of a cracked stock for the production of low boiling point products of motor fuel type which comprises passing an initial uncracked charging stock heated under superatmospheric pressure to a temperature below cracking into a primary vaporizing and fractionating zone, under lower pressure, wherein the charging `stock is substantially vaporized, condensing the vaporized fractions by contact with a cooling fluid, withdrawing from the fractionating zone the unvaporized fractions of the said charging stock .and heating them admixed with steam in a cracking zone under superatmospheric pressure range between 5 to 25 atmospheres, to a relatively low cracking temperature of from 800 to 900 F., ap-

proximately, passing the uncracked condensed fractions from the vaporizing and fractionating zone into a blending and separating zone wherein said condensate is completely vaporized by mixing it with the hot cracked vapors discharged from the cracking zone into said blending and separating zone and from which the residue and tarry material has been separated in said zone,

lpassing the mixed cracked anduricracked vapors pto a second fractionating zone, separating the from said second cracking zone into said blending and separating zone and blending the same with the cracked products of the first-named cracking zone, mixing the blended cracked vapors with the uncracked condensed fractions of the first-named fractionating zone to obtain overhead products of gasoline range and the synthetic recycling product.

3. A process for treating hydrocarbon oils which comprises the subjection of an initial uncra'cked oil charging stock to substantial vaporization in a zone through the aid of highly heated vapors passed into contact therewith, separating in said zone the uncracked virgin gas oil fractions of said charging stock from the gasoline range fractions, withdrawing said uncracked gasoline fractions from the zone and forming a condensate thereof, subjecting ,said virgin gas oil fractions to vaporization obtained by the sensible heat of cracked hydrocarbon vapors contacting therewith in a separating zone, passing the unvaporized portion of the charging stock from the rst zone to a heating Zone and subjecting the same to a cracking temperature of from about 800 to 900 F., approximately, for a time sufficient to substantially crack the same and discharging the cracked products into said separating zone, leading the mixed treated vapors from said separating zone and fractionating the same to obtain a 'recycle condensate comprising uncracked heavy fractions higher boiling than gasoline of the vaporized virgin gas oil and heavy fractions higher boiling than gasoline of said cracked products, subjecting said recycled condensate simultaneously with the said uncracked gasoline range fractions condensate to a cracking temperature of 900-1100 F., approximately, for a time sufllcient to substantially crack said condensate and reform said uncracked gasoline range fractions, and discharging said cracked and reformed products into the separating zone.

4. A process for forming hydrocarbons of the motor fuel type, which comprises, subjecting an initial hydrocarbon charging stock containing constituents of higher boiling point than gasoline constituents to substantial vaporization without substantial cracking in a "preliminary zone with the aid of a stripping action by highly heated vapors contacted with the charging stock, separating vapors from the unvaporized charging stock, fractionating the separated vapors to form a condensate of higher boiling range than that of gasoline, delivering liquid residual products into a second zone for separation of vapors form liquids, withdrawing the unvaporized portion of 'the charging stock and subjecting same to heat under conditions of temperature and pressure,

and for a time sufficient to effect substantial cracking thereof to form motor fuel hydrocarbons, passing the cracked products into the second zone, simultaneously passing into said second zone a condensate of higher boiling range than that of gasoline fractionated out of the vapors separated in the preliminary zone, passing vapors from said second zone to a second fractionating zone to condense out a fraction of higher boiling range than that of gasoline, subjecting said fraction to cracking conditions in a second cracking Zonato produce low boiling point hydrocarbon vapors, passing vapors from said second cracking zone into the preliminary zone to act as highly heated vapors for the stripping action.

5. A process in accordance with claim 4, in which cracked liquid residuals sent to said second zone form apool in an intermediate section of the second zone, and the cracked vapor and liquid residual products are injected into this pool.

6. A process in accordance with claim 4, in which liquids sent to the second zone form a pool in an intermediate section of said zone, the liquids being at a temperature at least equal to an incipient cracking temperature and injecting heated gaseous material to contact with the liquids in order to secure a high degree of vaporization. j

7. A process forcracking and converting high boiling liquid hydrocarbon materials to form lower boiling hydrocarbon products of the motor fuel type which comprises, heating the hydrocarbon materials under cracking conditions in a heating zone to form liquid and Vapor products, maintaining a pool of liquid products in an intermediate section of a separation zone at a high temperature to vaporize a portion of said liquid products in such a manner that residual portions of the liquid products in the pool are forced to separate and flow downwardly countercurrent to heated steam and ammonia vapors injected into the separation'zone below the pool so as to have a stripping action on the residual portions of said pool flowing downwardly, injecting into said pool,highly heated cracked products from said heating zone, removing gaseous and vaporized materials from the separation zone, cooling the stripped portions to form a second pool below the first named pool and removing residual portions from said second pool.

8. A process for forming hydrocarbon products of the motor fuel type, which comprises subjecting a preheated uncracked charging stock to substantial vaporization in a primary zone with the aid of highly heated hydrocarbon products of cracking containing fractions of boiling range of naphtha passed into contact with and flowing counter-current to the unvaporized fractions 'of the' charging stock to produce a solvent and a stripping action which substantially increases the amount of vapors, separating from said Vapors in said primary zone a thus formed substantially uncracked intermediate fractional condensate higher boiling than naphtha, withdrawing unvaporized charging stock from said primary zone, subjecting the same in a heating zone to a pressure, at temperature and for a time suiiicient to produce substantial cracking, delivering cracked products from said heating zone to a separation zone, passing the intermediate condensate from the primary zone to said separation zone to be revaporized by contact therein with cracked vapor products of said heating zone and of a second zone .hereafter described, passing mixed vapors from the separation zone to a fractionating zone to obtain a composite recycle condensate higher boiling than gasoline and comprising a portion of the revaporized intermediate condensate and cracked products, cracking said composite condensate under higher pressure and temperature than that applied to the unvaporized charging stock, and mixing the resulting cracked vapor products in said separation zone with the cracked vapor products of' the first named heating zone and said revaporized intermediate substantially uncracked condensate above described.

9. A process for forming hydrocarbon products of motor fuel type in which a preheated initial hydrocarbon charging stock is subjected to a solvent action and substantial vaporization in a primary zone through the aid of highly heated vapors from a heating zone passed into contact therewith and containing gasoline and naphtha,

simultaneously the unvaporized portion is suby ing zone under fsuperatmospheric pressure to a cracking temperature for a period of timepsufcient to produce 'substantial cracking, delivering .the cracked vapor and liquid products to aseparating zone, injecting into the hot cracked vapor products in said separating zone for its revaporization said intermediate fractional condensate from the primary zone, Ifractionating the vapors in a secondary fractionating Zone to separate out condensed fractions higher boiling than gasoline,

passing said condensed fractions from said second fractionating zone to a second heating zone in which said condensed fractions are cracked under superatmospheric pressure, mixing the cracked vapor products after separation from liquid, 4from said second heating Zone with the cracked vapor products from said first mentioned heating zone and the intermediate fractional condensate withdrawn from the primary zone to obtain overhead products Aof ,gasoline boiling point range and heavier products. I

10; A process for cracking hydrocarbons to .produce motor fuels, which comprises subjecting a hydrocarbon charging stock to vaporization in a primary zone to form vapors and residual oils with a minimum of cracking, subjecting the vapors to fractionation to separate out a fraction ofhigher boiling range than naphtha, passing from the primary zone residual oils substantially free from'tarry bottoms to a heat treatment zone wherein said residual oilsl are subjected to cracking conditions toL convert hydrocarbons into lower boiling point hydrocarbons, passing the resulting hot products from the heat treatment zone to a separation zone for separating vapors from liquids, vaporizing in said 'separation zone a petroleum fraction higher boiling than gasoline comprising uncracked constituents, passing thus formed vapor mixture from said separation zone to a fractionating zone to fractionate out a recycle condensate containing cracked anduncracked constituents higher boiling than gasoline, and passing'the recycle condensate to a second heat treatment zone for converting constituents in said recycle condensate 'under cracking conditions, in which'hydrocarbon products of boiling point range lower than gas oil and comprising fractions within the kerosene and heavy naphtha boiling point range are reformed by heating said products at a pressure not exceeding 60 atmospheres and not less than 15 atmospheres to a temperature above 1000 F., jointly with the recycle-condensate, maintaining the products in said temperature and pressure conditionsfor a time sufficient to split constituents of said recycle condensate, including gasoline constituents, and reforming said kerosene and heavy,naphtha boiling point range fractions and condensing and collecting a motor fuel product.

11. A process for cracking mineral oils to produce gasoline, which comprises subjecting to vaporization under expansion without substantial cracking an initial preheated raw mineral oil to form vapors and residual oilsin a primary zonfinjecting into said primary Zone a desulfurizing agent to absorb sulphurous impurities from the raw mineral oil, passing a portion of the unvaporized raw oil of reduced sulfur content from the primary zone to a heating zone to be heated under conversion conditions suiiicient to cause formation of gasoline, separating vapors comprising gasoline from liquid products of the conversion, fractionating the vapors of the conversion to form a condensate of higher boiling range than gasoline, subjecting said condensate in a second heating Zone 'to more severe conversion 15 conditions than imposed upon the unvaporized oil in said rst mentioned heating Zone, and passing productsy in heated condition from said second heating zone to said primary zone to aid in the vaporization of the initial raw oil.

12. A process in accordance with claim 8, in which vapor products from the separating zone including the fractions higher boiling than gasoline are subjected torening to remove sulphurous and other tar forming substances prior to fractionating the composite recycle condensate and cracking same.

13. A process for the conversion of hydrocarbon oils into refined gasoline motor fuels, which comprises heating the hydrocarbon oils in a cracking zone for a .time to form gasoline and under cracking conditions of temperature and pressure, passing products from the cracking zone to a separation zone maintained at temper.-

atures of about 700 to 800 F. for separating 35 vapor products from liquid products, admixing with the products at a lower pressure than that'. of the cracking zone and before entering the separation zone an .absorbent desulfurizing agent volatile at the said temperatures to refine the products, separating oil vapors thus refined from the thus treated products, further refining the separated vapors t6A remove from them undesirable sulphurou's and'tarry substances by ldirectly lpassing the separated vapors through a catalytic contact mass andsending the vapors refined by said contact mass to afractionating ,zone to separate out a refined condensate higher boiling than gasoline for further heat treatment under cracking conditions and product.

14. A process in accordance with claim 13, in which hydrogenating gases are mixed with the refined condensate, further heated under cracking conditions and at a pressure not exceeding 60 atmospheres and condensing and collecting a motor fuel product.

a refined overhead gasoline 15.` A process in accordance with claim 13, i

,which comprises reforming uncracked hydrof products, a furnace divided into radiant and convection sections, heating means in the radiant section, separate cracking coils disposed primarily within the convection section and having their outlets in the convection section of the furnace, one of said coils largely being in a radiant section and relatively nearer the heating means than the second coil and comprising a plurality of tubes at the highest section of the convection section communicating with a bank of tubes in the radiant section adjacent a wall which divides it from the convection section, the latter tubes communicating witha bank of tubes'in the radiant section opposite said division wall, the latter tubes communicating with -a roof bank of tubes in the radiant section, and the roof bank of tubes communicating with a main tube section disposed intermediate the rst named tubes in the convection section nearest the heating means and the tubes of the second cracking coil, the tubes of the second cracking coil comprising a plurality of tubes at a roof bank in the convection section and thence communicating with a main tube section disposed between the outlet section of the first named cracking coil and the said outlet section of the second named cracking coil, a blending chamber receiving the cracked products from both coils, a vapor separating tower receiving the cracked products, means within the vapor separating tower for maintaining a pool of liquid in the intermediate section of said tower into whichC the cracked products are discharged, means for maintaining a pool of liquid at the bottom of said tower receiving heavy and tarry residues not vaporized in said intermediate pool, a fractionating tower receiving the cracked vapors of the vapor separating tower by means of a ow connection intermediate the top of said vapor separating tower and the lower section of said fractionating tower, means for injecting cooling uid into said fractionating tower, a ilow connection between the botto-m of said last named tower and inletof the first named cracking coil, a primary vaporizing and fractionating tower receiving a charging stock, means within the last named tower for collecting unvaporized liquid at the bottom and'vapor condensate in an "intermediate section of said last named tower, a flow connection intermediate the outlet of the rst named cracking coil and the bottom of said primary vaporizing and fractionating tower for causing a flow of highly heated products to said tower to aid the vaporization of said charging stock, means for injecting said vapor condensate into said blending chamber' and separating tower, means for injecting cooling fluid into the upper section and lower section of said separating tower, means for injecting cooling fluid into the upper section of said primary vaporizing and fractionating tower, means for injecting sulphur removal agents into said primary vaporizing and fractionating tower, a flow connection between the bottom of said last named tower and the inlet of said second named cracking coil for conveying thereto the unvaporized charging stock, a flow connection between the top of said primary vaporizing and fractionating tower and a condensing means for condensing gasoline vapors, a flow connection between said condensing means and a separating tank, .a ow connection between said tank and said first named cracking coil, a flow connection between the top of said rst named fractionating tower and condensing means for condensing therein gasoline vapors, means for injecting steam into the bottom of said primary vaporizing and fractionating tower and into the bottom of the rst named fractionating tower, and means for injecting a solution of water and ammonia through a heat absorbent means into the bottom of the separating tower for a refining and stripping action.

18. A process in accordance with claim 11, in which the sulfur treated vapor mixture comprising vapors of the initial rawoil and vapors of the heated products passed to the primary zone to aid in the vaporization of said raw oil is con- V'densed, revaporizing'the condensate of reduced sulfur content in a zone distinct from the zone in which the vapor mixture was condensed, and subjecting the vapor products of the revaporization to fractionation jointly with (the vapor products of the cracking from the rst named heating zo-ne.

19. A process in accordance with claim 11, in which the vapor mixture comprising the vapors of the initial rawoil and vapors of the heated products from the second heating zone passed into the primary zone are fractionated to obtain overhead products of boiling point range lower than gas oil, condensing in said primary zone the heavy fractions of boiling point ranget of gas oil, revaporizing in a zone distinct from said primary zone said heavy fractions comprising un-A cracked gas oil fractions of the initial raw oil and gas oil fractions of the heated products from the second heating zone, and fractionating the vapor products of the revaporization jointly with the vapor products of the cracking from the first named heating zone.

ERNEST A. OCON.

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