US2731394A - Conversion of heavy hydrocarbon oils - Google Patents

Description

2 Sheets-Sheet 1 Filed May 25, 1951 o Paomucr Qacovamv 6 EN EEATOK S r w M m pvum 7 n n 5 a r v m I. Q. .U i 5 Q 7 W a 6 W L 7 r. 10 4 mam 2 1. EM L I W w 5 w a 2 m h A I.

Jan. 17. 1956 c. E. ADAMS ETAL 2,731,394

CONVERSION OF HEAVY HYDROCARBON OILS Filed May 25, 1951 2 Sheets-Sheet 2 1 Pkooucrrs QECOMDlTlONEQ v7 Fzom l QEGEMERATQR. L51 t. 59 WWJ WW. 71

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QoZvert Qflrebs QLarIL E. a ams Bavenbors Charles Y2. KtmberLtrz,Jr.

$38 W Clbboraeg United States Patent CONVERSION OF HEAVY HYDRDCARBON OILS (Hark E. Adams, Robert W. Krebs, and Charles N. Kimberlin, Jr., Baton Rouge, La., assignors to Esso Research and Engineering Company, a corporation of Delaware Application May25, 1951 Serial No. 228,234

6 Claims. c1. 196-49) The present invention relates to a process of treating hydrocarbons. More particularly, the invention pertains to a method of producing from relatively heavy or highboiling hydrocarbon oils of the type of topped or reduced crude or similar heavy residues increased quantities of motor fuel range fractions of improved quality as well as higher boiling distillate fractions suitable for further cracking. Broadly, the invention involves the cracking of heavy residues of the type mentioned above wherein the feed is contacted successively with fluidized catalytically inert solids and cracking catalyst in such a manner that the feed is heated to coking temperatures and freed of ash constituents in contact with inert solids while the cracking of the total volatile coking products takes place in contact withcracking catalyst, provisions being made for preventing coke fines, inorganic feed contaminants and droplets of heavy liquid product to reach the catalyst by entrainment in the eflluent from the coking stage. i In conventional petroleum refining the crude petroleum is first distilled to produce various distillate fractionsand a residue boiling above about 700 F. or, in vacuum distillation, even above 1050 F. Motor fuels are normally producedfrom the distillate fractions by suitable refining processes including thermal or catalytic cracking, reformns. isomerization, alkylation, etc., while the residue is worked up to yield marketable high-molecular Weight products such as lubricating oils, waxes, asphalt, fuel oils, etc. Morerecently, however, the demand for motor fuels has increased so greatly that it has become desirable to use the residues from the crude distillation extensively as an additional source of raw materials for motor fuels.

It has been known fora long time that motor fuels may be produced by coking crude residua, that is bysubjeetingthe residues to cracking at severe conditions including relatively high temperatures and long holding times. The use of cracking catalysts in this reaction has likewise been proposed. However, serious difliculties have been encountered in this type of operation chiefly as the result of the high ash content of the feed and the high rate of cokeformation. Aside from thefact that theheavy coke deposits inthe coking vessels and transfer lines require frequent cleaning periods and plant shutdowns, catalyst contamination and deactivation by coke and diflicultly removable ash constituents of the feed is so rapid that crude residuahave been considered highlyjundesirable as feed stocks for conventional catalytic cracking processes.

"Some of these difiicultiesmay be avoided in accordance with prior suggestions by coking residues in a denseturbulent bed of "hot subdivided catalytically inert solids such as coke, pumice, kieselguhn spent clay, sand, or the like fluidized by upwardly flowing gases or vapors. These solidsserve primarily as a carrier for the coke formed 2,731,394 Patented J an. 17, 1956 2 is a matter of record that fluid operation affords greatest advantages with respect to heat transfer and economy, temperature control, ease and continuity of operation, .etc.

While procedures of this type avoid catalyst contamination and heat supply by circulating catalyst, they are essentially thermal rather than catalytic in character and, therefore, result in the production of motor fuels of relatively low octane rating. The addition of a cracking catalyst in itself to the inert material is no complete solu tion of the problem because there still remains the difliculty of catalyst contamination and deactivation by ash constituents of the feed, which cannot readily be removed by simple oxidative regeneration. In addition, large amounts of inert solids must be circulated together with the catalyst between reactor and regenerator.

It has also been suggested to pass the entire volatile eflluent of a fluid type inert-solids coking zone without substantial heat loss directly to a separate fluid type catalytic cracking reactor. While this method affords important advantages with respect to heat economy, product quality, valuable product yields and continuity of operation, substantial proportions of coke fines, entrainedheavy liquid and particularly of catalyst poisons which cannot be removed by conventional gas-solids separation means still reach the catalyst bed and accelerate irreversible catalyst deactivation. The present invention overcomes this difficulty and aifords various additional advantages.

and as ascouring agent preventingrcoke deposition on t may abeareturnedao supplyheat requiredufor coking. :It

equipment walls, Also gasoline .yieldsare somewhat It is therefore the principal object of the present invention to provide improved means for producing motor fuels by coking heavy residua in contact with fluidized inert solids followed by catalytic cracking of the total volatile coking products. Other objects and advantages will appear from the description of the invention given below wherein reference will be made to the accompanying drawing in which Fig.1 is a semi-diagrammatical illustration of a system suitable to carry out a preferred embodiment of the invention; and i Fig. 2 is a similar illustration in simplified form of a desirable modification of the system *shown in Fig. 1.

In accordance with the present invention heavy residues of the type specified above are first contacted at coking conditions with a dense turbulent fluidized mass of catalytically substantially inert solids to convert the feed into lowerboiling volatile products and coke depositing on the inert solids and to remove contaminating ash constituents of the feed. The total volatile effluent of this coking stage together with entrained coke fines, ash dust and liquid droplets of unvaporized feed and/or product is passed without substantial heat loss directly into a separate dense turbulent fluidized guard bed of subdivided substantially inert solids. Liquid droplets are removed from the efiluent through limited wetting of the guard solids. The entrained finely divided coke and ash dust is retained in the guard bed as a resultof the wetting and the agglomera'tive tendency of fluidized beds, that is their tendency to retain particles which, according to Stokes law, would be entrained ifthey were in disperse phase. The volatile effluent of the coking stage thus purified is then passed from the guard bed directly and without substantial heat loss through a separate dense turbulent bed of fluidized cracking catalyst to complete the conversion. The: guard bed solids remove hydrocarbon liquid, coke fines and inorganic ash dust by gas displacement and selective entrainment. Thesolids so treated are returned to the guard bed; If desired a limited combustion may be'carried outainythe reconditioning zone to aid in the removal of combustible impurities and to maintain the guard solids at a desired high temperature. The solids thus reconditioned are returned to the 'guard bed.

, :In accordance with a specificembodiment of the inyention solids from the fluidized coking bed maybe used asguard solids. For this purpose, coked solids are con tinuously withdrawn from the fluidized coking bed,

stripped and elutriated in a conditioning zone at the desired temperature to remove adhering liquid and solids fines includingcoke and ash, and the solids so conditioned to'act as guard solids are passed to the guard bed wherein they are fluidized by the volatile coking zone efiluent passing'through the guard bed to the fluid catalyst bed as described above. Guard solids are continuously removed from-the guard bed and returned to the coking bed at the rate at which they are withdrawn therefrom. This rate should be so controlled that the guard solids are retained in the guard bed for a time insufficient to allow a build-up of the undesirable materials on these solids or to allow the guard solids to collect suflicient liqnidto become sticky. The latter condition is particularly critical in many cases in which it is desirable to maintain the guard bed at a temperature below coking temperature to cause a reflux of heavy coker product undesirable for catalytic cracking or to cool the coker effluent to a temperature more desirable for catalytic cracking.

While some of theinert solids previously suggested for; the coking of residues in fluid operation, such as sand, pumice, spent clays, silica gel, etc. may be used in the coking bed and/or the guard bed, coke affords greatest advantages in the process of the invention because product coke deposited on this material forms a valuable byproduct; which may be recovered as a high B. t. u. fuel, as araw material for activated carbon, and for other purposes, suchasin the manufacture of carbon electrodes, etc. Any gonventional cracking catalysts including activated clays, activated alumina, synthetic composites of silica; gel with alumina, magnesia, and/ or boria, etc., may housed in the catalytic cracking zone.

Fluidization conditions in all three beds may be maintained within conventional ranges. The particle sizes of the inert solids and catalyst depend, of course, to a certain extent on their relative densities. substantially equal densities ofthe order of that of conventional clay catalysts and coke, the particle size may be about -200 microns, preferably 50 to 150 microns.

'Linear superficial fluidizing velocities of the fluidizing Assuming 4 tions. The lower-most section servesas the coking zone containing the fluidized coking bed. The intermediate zone contains the fluidized guard bed supported by a perforated plate, while the fluidized catalyst is located in the top zone above the upper perforated plate. The feed is supplied to the bottom zone, volatile products flowing upwardly through the guard zone into the catalyst zone to be withdrawn overhead from the catalyst zone. This arrangement affords substantial advantages with respect to controlof coke deposition, heat economy, separation of the fluidized solids serving different purposes, as well as with respect to economies of construction and maintenance.

Having set forth its objects and general nature the invention will be best understood from the following description of the specific embodiments illustrated by the drawing.

Referring now in detail to Fig. 1, of-the drawing, :the system illustrated therein essentiallycomprises a-converter 5, an inert solids reheater 17, a guard solids re.- conditioner 39 and a catalyst regenerator 59. The functions and coaction of these elements will be forthwith described using the conversion of crude distillation bot; toms into motor fuels asan example. It should be un; derstood, however, that the system may be employed for the conversion of other coke forming feed stocks into the same or different products in a substantially analogous manner. in

In operation, reduced crude such as a 2.5 to, 3.5% 1 0i. toms fraction having an API gravity of about 12 from the vacuum distillation of a South Louisiana crude or a similar heavy residue is supplied substantially in the liquid state at a temperature of about 500-700 F. to line 1 which discharges through a spray nozzle 3 intodower zone A of converter 5 at a point above asuitablegas dis; tributing means such as perforated plate or grid 7.-,. Zone A contains a dense turbulent fluidized mass ofsolids hay;-

- ing an upper interface La. and maintained at about 850:

actions may be supplied in any conventional manner for example'by indirect heating of 'the fluidized beds or by a the preferred embodimentof the invention provides for l100'F. A fluidizing gas such as steam, hydrocarbon gases or ,vapors is supplied through line 9 and, grid 7 to establish a linear superficial gas velocity of about; 0.3-? ft. per second in zone A. Any of the inert solids men:

tioned above may make up the fluidized mass in zone A.

However, coke having a particle size of about 20-150 microns is preferred. The oilfeed rate to zoneA maybe about 0.1 to 4 weights of oil per hour per weight of fluidized solids in zone A (w./hr./w.), depending upon the temperature in zone A. At 800 to 950TF. thefeed rate may be about 0.1 to 0.8 w./hr./w.; at 95 0 ;-l05 0f. -F. the feed rate may be about 0.5 to 2.0 w./hr./w.; at temperatures above 1050 F. the feed rate may be about 1 to 4 w./hr./w. The temperature in zone A maybe main tained atabout 850 1100" F. as follows. 7, ,p p I Fluidized cokecarrying freshly deposited coke may be withdrawn through a conventional standpipe 11 pro; vided with one or more aerating and/or strippingtaps} in a conventionalmanner Product, coke amounting to about. 5v to 7 weight percent of the. residuumfeedmay be recovered via branch pipe 13. This amount of coke is the excess over that required for heat supply and applies in the case'of the South Louisiana residuum,here specified; varying amounts of coke will be, obtained from other feeds. The remainder of the coke discharges into air line 15 and maybe passed suspended in air-to the-bob tom of heater vessel 17 which it enters through-a distributing grid 19 to form a dense turbulent fluidized mass M17 above grid 19. Combustion takes place .in-mass Mm as a result of which the solids are heated to about .90 0.

an arrangement. of .all" three beds in a single substan-' 1300 F. Flue gases are withdrawn overhead .via line 21 preferably after fines separation and returnin cyclone 23 provided with dip-pipe 25. Reheated solids arewith; drawn from mass Mn through standpipe. 27 aerated and/or stripped via taps t and supplied ltozone A, sub stantially at the temperature of mass" Mrnf Fresh seed cokejpr the like maybe supplied via line 29 as re'quiteda Since: more coke is deposited. on the solids in zone A than .is required for heat generation in heater 17 the particle size of. the. solids may increase due to coke accumulation. To prevent this from. reaching proportions detrimentalto fluidization a grinding. stage may be incorporated in the system of circulating solids. For example, a supersonic attniter may be combined with standpipe 11 or 27 in a manner known per se in the art of catalytieci-acking.

\ Returning now to zone A of converter 5, the oil feed may be converted. therein to yield about 88 to 90 weight l per cent of volatile products on feed. This yield applies to: the South Louisiana residuum specified and differs with other feeds. Simultaneously, the ash contaminants of the feedtwhich. are present mostly inthe form of sodium chloride, calcium chloride, magnesium chloride and other similar inorganic salts and metal soaps such as soaps oftvanadium iron, chromium and nickel and other organo-metallic compounds the nature of which is not well understood undergo changes. as follows. :The inorganic salts remain essentially unchanged and are deposited on the'solidstin zone. A. However, themetal soaps and other organo-metallic compounds are convertedinto a fine dust of the oxides and/or carbonates, usually of microns particle size, which is. readily entrainable at the prevailinggas velocities. Volatile products containing entrained solidstfines, ash dustand dropletsof unconverted feed or heavy product pass overhead from level La through horizontal perforated plate orgrid Slarranged in an intermediate section of converter 5, substantially above level Ln. t

TheI gases and vapors passing grid 31 enter zone B of converter 5, which contains a dense turbulent mass of inert solids having an interface Lb, fluidized by the upflowing gases and. vapors. While the solids in zone B serving as the guardbed may be the same as those used in zone A, sandhaving a particle size of about 50-109 microns will bereferred to for the, purpose of the present example. Quite generally, it may bedesirable to use in zone B an inert solid of high attrition resistance to avoid losses in the subsequent reconditioning stage and excessive entrainmentin the upflowing eil'luent of zone A. The gasiform efiluent ofcoking zone A deposits in zone B its content of entrained cokefines, ash dust and liquid due to the agglomerative eitect of fluidized masses, referred to above. In order to maintain the: purifying capacity of the fluidized mass in zone the solids may be reconditioned asfollows.

Fluidized solids: may be withdrawn. from zone B through a conventional aerated standpipe 33 and suspended in line 35 in an elutriating and strippinggas such as steam, flue gas, or the: like. The suspension formed maybe passedthrough grid 37 into the bottom portion of. reconditioner 39, to form above grid 37 a. fluidized mass M39 having an interface L39. The linear superficial gas velocityin massMss may be readily so controlled, say within about l and 3 ft. per second, that the solids fines and ash dust are preferentially entrained and the liquid is stripped oil the sand, without substantial losses of sand particles. In order to maintain the temperature of the sand at that desired for the guard bed in zone B and to raid in'the removal of combustible liquid and solids fines it may be desirable to add small amounts of a combustion supporting gas such as air and/ or oxygen to mass M39 via=line 35. The temperature in zone B may be somewhat lower than that of zone A and should preferably not. exceed the temperature to be maintained in catalytic cracking zone C. Entrained solids and vaporized impurities are carried overhead from level L39 by the elutriating and stripping gas and may be vented via line 41; Reconditioned sand maybe returned through conventional aerated standpipe 43 to zone B substantially. atthe rate at which solids are withdrawn from zone B. Makeup stand may be added through line 45' I asrequired.

Volatile efiluent of zone B,.now free ofcatalyst poisons passes overhead from level Lb through a horizontal pen forated plate or grid 47 arranged in an upper section of converter 5 substantially above level Lb. Any en.- trained sand reaching grid 47 impinges on the impermeable portions of grid 47 and is mostly thrown back into zone B. Volatile products pass grid 47 to enter zone C of converter-5 which contains a dense turbulent mass of subdivided cracking catalyst, such as a silicaalumina composite containing about 13% of A; and having a particle size of about 20-150 microns. The catalyst mass is fluidized by the gases and vapors to form an interface L0. The temperature of the catalyst mass may be maintained at about 8001000 F. in any conventional manner, providing for cracking times of about 3 to 20 seconds. At these conditions extensive cracking of the gas oil constituents of the coking products into motor fuels takes place in zone C. A mixture of gasiform products and fiuidizing gases passes overhead from level Lc preferably through a cyclone separator 49 provided with solids return pipe 51. The product stream may then be passed via line 53 to conventional product recovery equipment (not shown).

ince coke is deposited on the catalyst in the course of the cracking reaction the catalyst must be regenerated. This step may be combined with heat supply to zone C in the conventional manner as follows. Coked catalyst is continuously withdrawn through a conventional stands pipe 55 provided with stripping and/or aerating taps t and passed to line 57 wherein it is picked up by air and conveyed to a lower portion of regenerator 5? via suitable distributing grid 61. The catalyst forms a dense turbulent fluidized mass M59 wherein the: catalyst is regenerated and reheated to about 900-l200 F, but above cracking temperature. Combustion gases are withdrawn through cyclone 63 and line 65. Separated catalyst fines may be returned to mass lviss via dip-pipe 67 or discarded via line 69. Regenerated catalyst is returned to zone C substantially at the temperature of mass M59 via standpipe 71 provided with aerating and/or stripping taps z. The sensible heat of the regenerated catalyst serves to maintain the temperature of zone C at the desired level.

Make-up catalyst may be added via line 73 as required. The system illustrated in Fig. 1 permits of various modifications. For example, the reheated inert solids may be returned to zone A via fluidizing gas line 9 through grid 7 or via oil feed line 1. In the latter case, substantial portions of the feed are vaporized in line it and the feed is preferably supplied through grid 7 without the use of a spray nozzle. Other modifications within the spirit of the invention will appear to those skilled in the art.

In many cases it may be desirable to exclude not only catalyst poisons and entrained liquid from the catalyst zone but in addition the heaviest constituents of the. vaporized coking product which have a particularly high. coke-forming tendency incatalytic cracking. A system suitable for this purpose is illustrated in Fig. 2.

Referring now to Fig. 2,. the system shown therein comprises the same major equipment elements as the system of Fig. 1, like elements being identified by like reference characters. The solids heater and catalyst regenerator have been omitted for the sake of simplicity. Operation of the system of Fig. 2 is substantially the same as that described with reference to Fig. 1 except for the operation of guard zone B, which may be as follows.

The volatile effluent of.. zone A is contacted in zone B with a fiuidized mass of the same solids which are used in zone A. The guard bed is maintained at a high puritying capacity and at a temperature somewhat lower than that of zone A as follows, coke being preferably used as the fluidized contact solid in zones A and B. Flnidized use 82in a stripping and elutriating gas such as steam,-

flue gas, etc. which may contain small proportions of a combustion-supporting gas such as air and/ or oxygen. In general, however, the introduction of combustion-supporting gases into line 82 is not desired. On the contrary, it may even be desirable to provide a small amount of cooling in addition to that provided by the stripping and elutriating gases. This may be done by injection of water into line 82. The suspension formed is passed into reconditioner 39 and treated therein substantially as described with reference to Fig. 1, reconditioned coke being passed to guard zone B via standpipe 43. Fluidized coke from guard zone B is continuously removed through a'down-comer 84 or the like and returned to coking zone A. Operation of reconditioner 39 may be readily so controlled that the coke in guard zone B is maintained at a temperature about-50 to 250 F. lower than that of zone Ato permit reflux of heavy coking products to the desired extent. The solids circulation rate from zone B to zone A, reconditioner 39 and back to zone B should be sufiiciently high, for example 300 to 1500 lbs. per barrel of residuum feed so that the time the coke is retained in zone B is insufficient to allow an excessive buildup thereon of materials undesirable in cracking zone C orto allow the coke in zone B to become so wet by condensed material that the coke becomes sticky.

The system of Fig. 2 may be modified as pointed out with reference to Fig. 1. In addition, heat may be withdrawn from the coke in reconditioner 39 or standpipe 43 in any conventional manner (not shown) to maintain the desired low temperature level in zone B. Other modifications obvious to those skilled in the art are within the spirit of the invention.

When operating as described above with reference to Fig. 2 catalyst poisons are withheld from zone C and, in addition, the coke-formation rate in zone C is substantially reduced by excluding the heaviest coking products which are further thermally cracked by their return the ash components of the residuum feed. This elimination of catalyst contamination by the metallic elementstof the residuum feed also results in a substantial saving by reducing catalyst replacement rate; for example, when 1 carefully avoiding catalyst contamination according to the present invention a catalyst replacement rate of only about 0.1 to 0.5 lb. of catalyst per barrel of residuum feed may suffice to maintain an advantageous level of catalyst selectivity and activity, but in the absence of means for avoiding the contamination of the catalyst by and resistance to contamination of the particular catalyst,

employed in zone C, and upon the amount and nature of the ash constituents of the particular residuum feed. Crude residua vary widely in the nature and amount of their ash content. from a non-desalted South Louisiana crude may contain as muchas 1600 lbs. per thousand barrels (PTB) of total ash comprising about 1200 PTB of sodium chloride, ,about 280 PTB of silica and "salts such as calcium and magnesium chlorides and about 120 PTB of metals such as iron, nickel," vanadium, chromium, and the like measured as oxides. Desalting the crude results in removing most of the soluble ash components, but very little of the heavy metal components which are the most desirable, of the ash constituents.

\ It will be appreciated. that the yield and quality of the products recovered'via line 53 will varysomewhat with As an example, a vacuum residuum.

8 1) the quality of the feedstock, (2) the severity of the operations in both the thermal zone A and the catalytic zone C, and (3) with the catalyst replacement rate employed in zone C. The following are illustrative of the yields, exclusive of thermal coke already mentioned, that may be expected when feeding a typical South Louisiana vacuum residuum, employing a catalyst replacement rate of about 0.5 lb. per barrel of feed and operating according to the present invention at intermediate severities in both thermal and catalytic zones: (1) 3 to. 10 weight per cent of coke, calculated on residuum feed, deposited on the catalyst in. zone C; this coke must be burned for catalyst regeneration; (2) 8 to 20 weight per cent of gas (C3 and lighter) including about 4 to 11 weight per cent of propylene which may be polymerized to further increase the yield of gasoline; (3 38 to 55 volume per cent of gasoline boiling up to about 430 F., and having an octane number by the Research Method of about 90 to 96; (4) 10-20 volume per cent of heating oil boiling in the range of about 430 to 650 F and (5) 15 to 25 volume per cent of heavier products boiling above about 650 R, which may be recycled to the thermal conversion zone A.

On the other hand, failure to avoid contamination of the catalyst by ash and the heavy components of the feed results in a marked increase'in catalyst coke deposits and of dry gas yields with a corresponding loss in yield of gasoline and other liquid products. The catalytic coke deposit may be as much as doubled and the gas yield increased by 50% by contamination of the catalyst even when employing a higher than desirable catalyst replacement rate. It is, of course, possible to alleviate these high coke and gas yields to some extent by employing excessive rates of catalyst replacement; but this isuneconomical as compared to the present method of pro tecting the catalyst from contamination.

The above description and exemplary operations have served to illustrate specific embodiments of the invention but are not-intended to be limiting in scope.

What is claimed is:

1. In the process of producing lower boiling hydrocar bons from heavy hydrocarbonaceous residues which tend to produce finely divided contaminants for catalysts by coking said residues in contact with a dense, turbulent, fluidized mass'of catalytically substantially inert solids maintained at a coking temeperature in a coking zone and passing the volatile coking products including entrained particles of heavy liquid without intermediate condensation of constituents desirable for cracking through a dense fluidized mass of cracking catalyst maintained at a cracking temperature, the improvement which comprises maintaining in a vertical elongated contacting zone a lower dense fluidized mass catalytically inert solids at a coking temperature, an intermediate separate dense fluidized mass of catalytically inert solids which is maintained at a temperature not exceeding the coking temperature in the lower mass and sufliciently low to' collect high boiling hydrocarbons from coked vapor products in sufficient quantities to separate catalyst contaminant'materials from said vapor products by adhesion, and an upper separate dense fluidized mass of cracking catalyst maintained at said cracking temperature, feeding said residues to said lower mass, passing voltatile eflluent of said lower mass in series upwardly through said intermediateand upper masses, separating the entrained liquid particles and finely divided contaminants in said intermediatemass by adhesion as aforesaid, withdrawing catalytically cracked volatile products from said upper mass, passing solids from said intermediate mass to a separate reconditioning zone, removing constituents undesirable in catalytic cracking from said solids in said reconditioning zone and returning solids so reconditioned to said intermediate mass.

2. in the process ofproducing lower boiling hydrocarbons from heavy hydrocarbonaceous residueswherein finely divided solid contaminants for cracking catalyst:

9 are produced, along with oil products, by coking said residues in contact with a dense, turbulent, fluidized mass of catalytically substantiallyinert solids maintained at a coking temperature in a coking zone and passing the volatile coking products without intermediate condensation of constituents desirablefor cracking through a dense fluidized mass of cracking catalyst maintained at a cracking temperature, the improvement which comprises maintaining in a vertical elongated contacting zone a lower dense fluidized mass of catalytically inert solids at a coking temperature, an intermediate separate dense fluidized mass of catalytically inert solids at an elevated temperature not substantially exceeding said cracking temperature and such that high boiling hydrocarbons in the vapor stream are condensed on said inert solids and entrained catalyst contaminants are caused to adhere thereto by reason of such condensation, and an upper separate dense fluidized mass of cracking catalyst maintained at said cracking temperature, feeding said residues to said lower mass containing particles of heavy entrained liquid and catalyst contaminant particles, passing volatile eiiiucnt of said lower mass in series upwardly through said inter mediate and upper masses so that the entrained liquid particles cause limited wetting of said intermediate and the catalyst contaminant particles adhere thereto, withdrawing catalytically cracked volatile products from said upper mass, passing solids from said intermediate mass to a separate reconditioning zone, passing a gas upwardly through said solids in said reconditioning zone at conditions conducive to remove said contaminants from said solids by elutriation, and returning solids so reconditioned from said reconditioning zone to said intermediate mass.

3. The process of claim 2 in which said gas contains suflicient free oxygen to support a combustion of combustible liquid constituents present in said reconditioning zone and to maintain in said reconditioning zone a solids temperature conducive to the maintenance of said elevated temperature.

4. in the process of producing lower boiling hydrocarbons from heavy hydrocarbonaccous residues which produce finely divided solid contaminants for cracking catalysts along with volatile products by coking said residues in contact with a dense, turbulent, fluidized mass of catalytically substantially inert solids maintained at a coking temperature in a coking zone and passing the volatile coking products without intermediate condensation of constituents desirable for cracking through a dense fluidized mass of cracking catalyst maintained at a cracking temperature, the improvement which comprises maintaining in a vertical elongated contacting zone a lower dense fluidized mass of coke at a coking temperature, an intermediate separate dense fluidized mass of coke at an elevated temperature substantially below said coking temperature, and an upper separate dense fluidized mass of cracking catalyst maintained at said cracking temperature, feeding said residues to said lower mass, passing volatile efiluent from said lower mass in series upwardly through said intermediate and upper masses, withdrawing catalytically cracked volatile products from said upper mass, entraining sufiicient high boiling hydrocarbon from said lower mass to adhere to said intermediate mass and help separate said solid contaminants from the efiduent by adhesion passing coke including condensed heavy coking products and deposited solids fines from. said intermediate mass to said lower mass, passing coke and solids fines from said lower mass to a separate reconditioning zone, passing a gas upwardly through said reconditioning zone at conditions conducive to remove solids fines from said coke by elutriation, and returning coke so reconditioned to said intermediate mass at a temperature and rate conducive to the maintenance of said elevated temperature in said intermediate mass.

5. The process of claim 4 in which said coke passed to said reconditioning zone is cooled by direct contact with water.

6. The process of producing lower boiling hydrocarbons, suitable for catalytic cracking, from heavy hydrocarbon oil which contains potent metal-containing contaminants for cracking catalysts, which comprises contacting said oil with a mass of preheated. essentially noncatalytic particles suspended or fluidized in a gasiform stream at a coking temperature between about 850 and 1150 F. for a period of time sufiicient to vaporize and crack thermally a substantial part of said oil with concomitant production of droplets of high boiling oil and metal-containing contaminants suspended in said gasiform stream and in the vapor products of conversion, establishing a cooler mass of the essentially non-catalytic solid particles aforesaid in the form of a fluidized bed, passing said gasiform stream and said vapor products upwardly through said cooler mass at such a rate as to strip out said droplets and contaminants onto said solid particles, and continuously cycling solids between said cooler mass and a fluidized solids reconditioning zone operated at a temperature 50 to 250 F. lower than said coking temperature whereby the temperature Within said cooler mass is continuously maintained at the level required for eiiective separation of said metal-containing contaminants from said vapor products.

References Cited in the file of this patent UNITED STATES PATENTS 2,367,351 Hemminger Jan. 16, 1945 2,388,055 Hemminger Oct. 30, 1945 2,448,135 Becker et a1 Aug. 31, 1948 2,483,485 Barr Oct. 4, 1949 2,525,925 Marshall Oct. 17, 1950 2,548,875 Degnen et al. Apr. 17, 1951 2,690,990 Adams et a1. Oct. 5, 1954

Claims (1)

1. IN THE PROCESS OF PRODUCING LOWER BOILING HYDROCARBONS FROM HEAVY HYDROCARBONACEOUS RESIDUES WHICH TEND TO PRODUCE FINELY DIVIDED CONTAMINANTS FOR CATALYST BY COKING SAID RESIDUES IN CONTACT WITH A DENSE, TURBULENT, FLUIDIZED MASS OF CATALYTICALLY SUBSTANTIALLY INERT SOLIDS MAINTAINED AT A COKING TEMPERATURE IN A COKING ZONE AND PASSING THE VOLATILE COKING PRODUCTS INCLUDING ENTRAINED PARTICLES OF HEAVY LIQUID WITHOUT INTERMEDIATE CONDENSATION OF CONSTITUENTS DESIRABLE FOR CRACKING THROUGH A DENSE FLUIDIZED MASS OF CRACKING CATALYST MAINTAINED AT A CRACKING TEMPERATURE, THE IMPROVEMENT WHICH COMPRISES MAINTAINING IN A VERTICAL ELONGATED CONTACTING ZONE A LOWER DENSE FLUIDIZED MASS CATALYTICALLY INERT SOLIDS AT A COKING TEMPERATURE, AN INTERMEDIATE SEPARATE DENSE FLUIDIZED MASS OF CATALYTICALLY INERT SOLIDS WHICH IS MAINTAINED AT A TEMPERATURE NOT EXCEEDING THE COKING TEMPERATURE IN THE LOWER MASS AND SUFFICIENTLY LOW TO COLLECT HIGH BOILING HYDROCARBONS FROM COKED VAPOR PRODUCTS IN SUFFICIENT QUANTITIES TO SEPARATE CATALYST CONTAMINANT MATERIALS FROM SAID VAPOR PRODUCTS BY ADHESION, AND AN UPPER SEPARATE DENSE FLUIDIZED MASS OF CRACKING CATALYST MAINTAINED AT SAID CRACKING TEMPERATURE, FEEDING SAID RESIDUES TO SAID LOWER MASS, PASSING VOLTATILE EFFLUENT OF SAID LOWER MASS IN SERIES UPWARDLY THROUGH SAID INTERMEDIATE AND UPPER MASSES, SEPARATING THE ENTRAINED LIQUID PARTICLES AND FINELY DIVIDED CONTAMINANTS IN SAID INTERMEDIATE MASS BY ADHESION AS AFORESAID, WITHDRAWING CATALYTICALLY CRACKED VOLATILE PRODUCTS FROM SAID UPPER MASS, PASSING SOLIDS FROM SAID INTERMEDIATE MASS TO A SEPARATE RECONDITIONING ZONE, REMOVING CONSTITUENTS UNDESIRABLE IN CATALYTIC CRACKING FROM SAID SOLIDS IN SAID RECONDITIONING ZONE AND RETURNING SOLIDS SO RECONDITIONED TO SAID INTERMEDIATE MASS.

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