US2406555A - Process for the conversion of hydrocarbon oils - Google Patents

Description

Aug. 27, 1946. H, z, MARTIN PROCESS FOR THE CONVERSION OF HYDROCARBON OILS 2 sheets-snee; 1

Filed Sep'l..A l5, 1941 Patented Aug. 27, 1946 UNITED STATES PATENT OFFICE PROCESS FOR THE CONVERSION 'OF HYDROCARBQN lOILS Homer Z. Martin, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware Application September 13, 1941, Serial No. 410,657

residualoils, into motor fuel constituents. 5 quent intervals. In other cases, when operating It has been heretofore proposed 'to crack oils to .form a coke residue it has been the practice in the presence of a vcracking catalyst to form 'to collect .the coke formed in .separate coking gasoline of relatively .high octane rat-ing. vessels from Which the coke may be, .removed According to one general mode of operation, the by mechanical means. A oil in vapor formis passed through a cracking l0 In all of the above cases, the treatment of zone containing -a xed mass of catalyst7 preferthis residual ,fraction for production of additional 'ably in the 'form of pellets or molded units, loquantities offgasoline has required a considerable cated Wit-hin the .reactor and supported on a investment in additional equipment. perforated tray or a plurality of trays. During One of the primary objects of thevpresent inthe cracking process the activity of the catalyst '11:5 vention yis to provide .a process .for catalytically rapidly depreciates due to the formation oicart bonaceous deposits. In View of this, .it is necessary in xsuch operations to interrupt the crack# ing process frequently .and regenerate the :catalyst mass by burning the carbonaceous deposits.

therefrom. In order to avoid the forma-tion of excessive -coke deposits, which in turn reduces the productive capacity of the cracking chamber, it has been the practice to first vdistill and fracit has also been suggested to lcarry out the coking treatment in the presence .of a relatively inert solid material which forms a carrier for the coke and from which the coke maybe -bu-rnedat .fre-

craeking crude oils to the desired vconversion in a single stage without .the necessity .of first separating a .heavy residual fraction therefrom.

A further important object .of the invention vis to provide .an .improved process for cracking crude yoils or residual .oils which Will require .less etpiipinent .for .a .cracking plant :of .given capacity and for va given quantity of .motor fuel produced.

A fur-ther secondary object of the invention tionate 'the crude Ioil and to pass only the cleanl -25 is to provide an improved process and apparatus vapors in contact with the catalyst and to reject for cracking residual oils which will .take .better a heavy residual fraction which tends to form advantage; Yof the heat liberated during .the reexcessive amounts of coke during the cracking generation'of the catalyst .for carrying out the process. This method Vof operating-not only recracking process.. Y 1 f quires the provision of diS'tilli-ng equipment for '30 Other more .specific objects oi' the .invention preparing a clean feed stock .for the cracking Will be apparent from the more .detailed descrip- 'process but also requires the `rejection of a subtion thereinafter. f v v stantial amount of the original feed .in the form In accordance with the broader phases of the of a residue which is not normally suitable for present invention, ac-ruderesi-dual fraction, such cracking treatment for the production of Ihigh 35 as a topped -or reduced crude, or, in certain cases, octane `gasoline Without additional processing. the `entire crude, is contacted with ahotadsorp- This rejected fraction may amount to from 5% -tive catalyst in subdivided state at a materially to 40% of the original crude, depending upon the higher temperature level than the oil, the amount nature of the `crude oil. This residual product of catalyst being ycontrolled with respect to the 'in many cases is consequently marketed as fa, 40 temperature thereof so that the oil upon contact heavy fuel oil. with the catalyst is promptly converted into va- However, this residual fraction contains a subp'ors, except for some residual oil which is `cornstantial portion .of oil 'which can be :converted pletely adsorbed by the `catalyst withoutcausing into high-grade Ygasoline with additional processthe latter to become tacky .or sticky. V- The -reing. For example, it has been the practice ,in 45 `sult-ing mixture, therefore, consists of relatively some cases to sub-ject this heavy residual rrac- `dry oil 'vapors 4and discrete particles of catalyst tion to a yseparate yand :independent (cracking 'or containing the heavy constituents adsorbed viscosity breaking treatment to convert the same therein. y into the maximum of overhead vapors suitable The resulting ydispersion Iof. catalyst powder for .further cracking under con'ditions controlled 50 containing the residual constituents adsorbed for .the product-ion of improved octane gasoline. In other leases; it has been the practice to convert all of this residual fraction into overhead vapors suitable vfor ,further cracking with the exception of the Ycoke residue. In the latter case,

therein and the oil vapors .is then passed through va cracking .chamber in which the desired .con- Version is accomplished.

As distinguished from viscosity breaking oper atiQns of the type hereinbefore described, the

ating zone.

iparatus suitable for carrying the invention eii'ect, and

present invention contemplates the conversion of Va substantial'portion amounting to at least 30% oil vapors are retained within the cracking zone.

This makes possible a greater utilization of the i catalvst between -regenerations and permitsV retaining the catalyst within the cracking zone until its activity has dropped to a point Vwhere regeneration of the catalyst is desired.

` This retention of the catalyst within the cracking zone for a period substantially longer than l designates a charge line through which the oil to be processed is introduced into the equipment. This oil may be, as previously described, a residual oil, such as a crude petroleum, `or

products from the process.

so introduced may be forced by feed pump Il through line I2 toa trimming coil I3 located in the top of product fractionator I4 in which the the time of residence of the oil vapors therein Y Following the cracking process. the catalyst is` separated from the cracked products either within or without the cracking zone and the cracked productsv fractionated in a conventional manner to segregate the desiredproducts.

The catalyst so separated is then regeneratedV to remove the carbonaceous deposits formed durling the cracking treatment. The regeneration lof the catalyst is preferably carried out at the `maximum premissible temperature which will `avoid permanently impairing the activity of the catalyst so as to make available for the cracking voperation the maximum amount of heat liberated Iduring the regenerative treatment and the catalyst so regenerated is immediately contacted `with the oil while at substantially its maximum regenerating temperature. In order to operate the regenerating chamber at the maximum temperature level. it is important vto avoid localized overheating of the catalyst within the regener- This is accomplished, `according to one of` the specific phases of the invention. by

constantly agitating or churning the catalyst within the regenerating zone, and. according to one of -the additional'phases of the invention,

this agitation or churning is accomplished by the flow of the regenerating gas through the re- Having set forth the general nature. objects ,and advantages, the invention will be described' in more detail in which reference will be made to the accompanying drawings wherein- Fig. I is a diagrammatic illustration of an apinto Fig. II is a similar View of a simplified apparatus wherein the total heat requirements for lcarrying out the process are obtained by direct contact with hot catalyst.

Referring toiFig. I, the reference character I0 cracked products are fractionated. The oil after passing through the coil I3 may be passed through line I5 to a second heat exchange coil IB located in the bottom portion of the fractionating ytower I4 or in a heat exchanger associated with the bottom portion of the fractionating tower. -The oil after Vpassing through the second preheating coil I6 may then be passed through line I1 to a heat exchanger I8 wherein it passes in heatA exchange relation with spent regenerating gases removed from the regenerating zone, as hereinafter described. The oil after passing through the heat exchanger I8 is passed through line` I9 to a heat exchanger 20 where it passes in indirect heat exchange relation with' 'hot catalyst undergoing regeneration. l

The oil after passing through heat exchanger 20 is transferred through line 2l to a second heat exchanger 22 wherein it picks up additional heat from hot catalyst undergoing regeneration as later described. y -Y When operating on total crudes containing substantial amounts of gasoline, it may. be desirable in some cases to rst distill thestraightrun gasoline. For example, in lieu of passing the crude loil in heat exchangewith cracked products in the product fractionator I3, crude oil introduced through line I0 maypass through line 23 to a crude stillZlI wherein the oil'is heated to a temperature of from 400 F. to 600 F., sufrating chamber 25 wherein the vapors formed separate from the remaining liquid. The vapors in separator 25 pass overhead to a condenser 26 wherein the straight-run` gasoline vapors or other low boiling vapors are liqueed. Products from condenser then pass to a distillate receiver 21. Liquid is Withdrawn from yseparator .25 through line 28 which merges with feed line I'I.

The oil duringV its passage through the heat exchangers and crude still hereinbefore described.

` or any combination thereof, is preferably preheated to a temperature of from 400 F. to an incipient cracking temperature, such as, for example, to a temperature of from 700 F. to 800 F. The oil after being preheated to a temperature of from 400 F. to 800 F. by passing through one or more of the .various heat exchangers is passed f located at Va point preceding the catalyst dis'- charge line 30. For example, the pressure on the oil passing through the preheating equipment may range between 50 and 500 pounds per square For example, the oil lamme-e should :not be iin fexcess '.of that lwhichiican be Acompletely adsorbed by the catalyst particles `without causing the catalyst .particles to become .adhesive :and 4iorm :a 44Vtacky, .sticky mass. :The .amount .of such Icatalyst introduced into the foil :vapors 4will Idepend 'upon :the temperature iof :the :catalyst and lthe :temperature of the .foil at the yplacedzhecatalystisrnixedwithithezoii. l EIllre famount 'of .catalyst introduced "into the-oil stream may .range :between .1 .and =45 4parts -zof catalyst per part fof'oilbyrveightpdepending upon ".the fnature iof'ftlreoil,y temperature :of fthe catalyst, theldegree'o'f :pretreatment andsother factors. In most 1cases the 'zratio will .':be lbetween 5 `andt20.

uThis VYcatalyst may comprise any vradsorptive :material capable yof :catalytically effecting the y.cra-'cking operation. vSuch material may comprise, for-.example Anatural clays for 'clays which `have fb'een .activated Eby suitable 4Itreatm'ent, Lsuch as with fa'cid, fto remove :impurities which may affect vthe fcracking or regenerative 'properties of 'fthe catalyst. .Inlieu ofthematural materialsuc'h Yas clays, 'the catalyst may :consist `of synthetic adsorbent materials, such Jas, for exam-ple, I synthetic .gels of silica fand-alumina or silica and magnesia, alumina, lboric :oxide fand others.

YThe .cata1yst introduced "into the 'oil stream rshould be in subdivided estate, the size of the particles ranging :from a nne powder, such fas '400 zmesh or finer, up to relatively .coarse lgranules, such as from 5 to 10.mes`h.

"The resulting -dispersion "consisting vessentially of oil vapors which have been fvaporized by contacting with the Iho't "catalyst land by reduction fin pressure througlhftlre lreducir-1g valve i3! and 'the catalyst containing the 'unyaporiza'ble constitu- 'ents of .the .oil 'adsorbed 'therein "is ipassedithrough erably in the :form .of =a vertical tower through which the dispersion isftorced to pass in 'an iupward Ydirection against the tforce iof gravity. 'The lower 4portion ofthe cracking :chamber T33 may fbe provided 'with va .perforated plate F34 below which is ,a portion of reduced diameter.. ".Ihe yelo'city .ofl fthe oil'stream Lpassing upwardly through the cracking chamber .'33 ils preferably 4controlled so that .the catalyst .contained in the stream y-of 'o'il vap ors iten'ds to Ysettle 'from :the ga's stream. As vra "result, the idensity I*ofi-the #catalyst fwithinthe re- "actor -fis'm-aterially greater thanv 4is the density lin thefstreamof'oil in *the lfeed line 32"1e'adirig thereto; The ydensity :in 'the reactor, rorexamplefmay rrange from 5to 20 pounds per vcubic-'foot "in cases .fof activated clays, Whereas the V.density of the nfgiven .regeneration temperature to -slmplyithe .heat- 1 f i 1 fatter l.passing through #the crack-ing chamber Agasp'line .constituents are liqueed '.T-hefstream :of fcracked products :and mil iis .passed through "Iin'e :3.5k :to Ava primary separator 136 :for the separation :of 'the catalystk from ithe .cracked vapcrproducts. This:separatormayhe lof a'ny conventional type :suitable .'for .segregation :of solidsaffrom vgai'ses .fand .ih-as .been illustrated .The #catalyst *the formcf a cyclone separator.

removed from the cracked products during pas- 'sage 'through the primary separator `3B discharges -in-to fa vertical ftube T31 :from `whence .it is passed Y :to :a regenerating chamber, 'as flater described.

.'Illre `cracked Wapors after having the .bulk `rif the catalyst'removed therefrom in :the :primary :separator v:maybe passedzthrough line 38 tera secondary separator :39 '.f'or urther removal iof the catalyst material. l,'Ihe 'fcatalystfseparated in 'the :secondary separaltor 39 'discharges Athrough .line 40 :finto the bottom section fof the :primary :separator '.36 where it imixes'with catalyst sepa- .irated in the 'primary cyclone :36. The .bottom portion fof .the :primary .separator 13.6 may "be provided -with suiiicient volume ito form va :storage .hopper capable of maintaining v'a reserve `supply iof catalystfor 'the process. .Steam for Iother stripping :gas may vbe'iritroduced into the bottom 'of :the separator -36 through line "4| to 'strip 'volatile vcracked 'products ifr'om 'the 'catalyst beforepassin'g the same to :the regenerating zone.

z'Ilhe :cracked 'vapors fatter passing throug'hithe 'secondary separator l39 ma'y be passed vfto iad'die `tional cyclones, electricalprecipitatorsibag'lters, or l.other separators (not shown) Afor'furtlrier fpurification. The cracked products fatter separation from :the -natalyst are 'passed ".:fthrough llinel' to :the Aproduct 'tractiona'tor il!!! wherein `vthe cracked 'products :are afractionallyicond'ensed to segregate.

the :insufliciently .criacked' 'constituents as conydensate. The shear/y condensatefformed in fthe .bottom section fof fthe ijfra'cti'onating 4'tower' fil-fis Withdrawn ttherefromwthrough "line M 1and may rbe removed :from the system-or 'it may be lcoin- ?bined witntreshiiieed through dine M vand pump :d5 `for funthercraohing fitreatment. lmateri al may :contain "..traces .of the catalyst employed "in the-cracking 'operation which are not completely removed in fthe separating iequipment. By lrecycling this .fractionto .the cracking equipment, .the catalyst contained therein may be 'returned ltoitheprorcess. @ne ormore condensates formed .in thefractionating tower '14 may lbe ycolllectedin 'trap-'out itra'ysfllf and '41V :and vremoved ffroni the system through-lines I"48 :and 9, frespectively.` -For l .exampleaDieseL heating or fumac'eloi-l-may be collected in: the vtop 'trap-out Itray v'M and a :gas -oilifractionimay be collected in the trap-'out trayd; i f

` '.The'orackedyapors remaininguncondensed in v thezproduct -fractichater 1"4 and containing the- 4.bulk 'of l'the gasoline 'constituents 4iorm'ed during the ioperation pass `overhead Tt'hrough .linegzol lto .-'a'product condenser ISZ 'inifwhicl the y 'Products :from the :ic 'ensei' i532 pass fto 1a receiver f53'in which ftle .f iquid forrned 'in the condenser 52 segregates ifi-om normally gaseousconstituents formed during the cracking mloeratiofi. The

liquid distillate separatedin 'i'fhefprcduct'receiver 513 `may be kW"tl-i'draxyn "therefrom ithrough fline 54 and the norm-ally gaseous'constituents 'may jbe Withdrawn 'through .line 55 andfpassedto a suituableiabsorptionL-or :recorre-ry' .equipment -iorzfremoying `normally @liquid constituents'. :entifa'ined` A"therei'nc -V Returning tofnolumn' A3?! :receiying spent catalyst l v alyst forreturn to the 'cracking Zone. 1 other inert strippinggas may be introducedinto` the bottom of the hopper 65 through line 65 to remove regenerating gas from the catalyst before f. returning the catalyst to the cracking process and -to maintain-the catalyst in a fluidized condition. The bottom of the center hopper or'compartment 1 65 isin open'communication with catalyst tube 30 which-in turn-discharges into the The velocity, ofthe oxidizing .gas -passing 'through the regenerating chamber: 58 is preferably adjusted to permitthe Vcatalyst particles to ji'orm into a relatively densebed of kcatalyst .within i the. regenerating chamber through which the regeneratingA gas must pass.- By'regulating the velocity of the regenerating gas passing through '"st'ream f of.; catalyst and regenerating. .1 gas.

distribution. i q f As previously vantage to transferheat from hot regenerated `'Ihe annular spacg below the perforated plate will then .form a. distributing zonefor the catalystfgas suspension passing onto the main bodycf the -regenerating chamber; VItiis sometimes, desirable to introduce thefincoming stream ataplurality of points around the annular space to improve wset forth, it is sometimesof ad- -cataly'st'tothe fresh oil feed in indirect heat exthe regenerating chamber within certain limits,

the catalyst bed or mass within the regenerating l --chamber may be made toassume the appearance vof a violently boiling liquid so that the` catalyst --particles are continuously and thoroughly mixed.

` -As la result, a `substantially uniform temperature may be maintained throughoutthe full depth of 3 the catalyst mass and localized overheating can be avoided. The velocity of the regenerating gas passing through the `regen-erator may beni thel -order of from 1/2 to 10 feet persecond, depending upon the size cf the catalyst particles, density and other factors. For example, when yemploying activated clays having a particle size between- 200 and 400 standard mesh, the velocity of the regenerating gas passing through the regenerator 1 .should be between 1 and 5 Vieet per second to .obtain the above-mentioned results.

j, I'he ,spent regenerating 1 gas after passing;` I :through the regenerator 58 isremoved overhead r--through line 59 andv is passed to'a separator 6l] .in which catalyst powder `entrained inthe gas is separated from the regenerating-gases. The catvalyst.powder-collectedin the separator 60 is removed through line 6| and returned to the regen- .erator- 5B- The regenerating gas after 'passing Vthrough the separator 60 passes through line'62 to thev heat exchanger. I8 through which it may pass-inindirect lheat exchange relation-with thev `fresh feed, as previously described. The regen-` erating gasY isV removedfrom the heat exchanger I 8 through line 63 and may bepassed to additional separating equipment, such agan electrical V,precipitator -(not shown) for removing finali traces of catalyst powder.` ThisV regenerating gas may also lbe passedto a' waste heat boiler or other wheat, recovery `equipment "(not shown) 5 Referring again to the regenerator v58, the bot- -tom-section'of the chamber is provided with aver-1. tical, circular partition wall spacedtfrom' the outer wall ofthe chamber to form a central comparta Steam orv oil feed line through a control valve61.

y The stream of regenerating-gasand spentcaty .l V.alyst from the cracking process passing'th'rough `line 51 is introduced into the regenerating cham` -ber-58 in the annular space between the circular portion Gland the outer wall of fthe regenerating chamber. An annular perforated plate'68-may be,;provided above-the.' inlet Lfor. the. incoming i changers and 22,7'althoughthis step .maybe omitted in manycases, as laterdescribed. :To this end hot regenerated catalyst vcollected inthe :central hopper 65 of regenerating chamber58 may be Withdrawn through tubes 69 and 16 and discharged into a stream of regenerating' gas such -as air or inertgas-introduced through linesfll and '12, respectively,'which--carries'the hot -acatalyst throughv lines 13- and 14 into heat exchangers 2l) and -22 where it passes inindirect heat ex-V changev with fresh-.feed as previouslydescribed.

The l.suspension oihotL regenerating gasr after passing through heat exchangers 20 and 22is returned to the regenerating-@chamber through lines 80 and '15.below'the'perforated .plate 68'.'

- The invention, as previously described, involves the stepof preheating the oil by indirect Contact Y with hot catalyst and then contacting with hot catalyst :to complete the heating. While 4this method of operating has denite advantages. in many cases, the invention also-contemplates the -omission of the preheating step 'by indirect heat .ingzone into the oil stream. Y Referring to Fig'. II, for-purposes of and brevity parts corresponding to those show-n exchange in catalystheat exchangers 20 and22. When operating in'thismanner, heat;` exchangers 26 and22 may be omitted ora part or all of the feed oil after passing through heatA exchanger I8 may be by-passed around the heat exchangers 29 and 22 through line 16. i* Fig. II illustrates afsimpliied Vform-of'I apparatus wherein the tota1 heat requirements 'for the cracking operation arevsupplied by direct injectionof hot catalyst removed'fromfthe regeneratin Fig.V I have been identiiied by prime numbers.

NfIn Fig'. II,-the oilV to, be charged, which may be through line* Hl".

ya 'topped-crude 0r any type of -feed stock mentioned hereinbef'ore, is vintroduced intothe sys'-y tem at :substantially vatmospheric vtemperature Y The oil; with or without being first preheated bypassing-:in heatl exchangeV with products undergoing fractionation Yinl heat exchange coils v`|3- and-I6 isi transferred through vline ll'v vinto whichjthe-hotv solid material is' introducedthrough conduit 60. provided Vwithj-a l mentor hopper for collecting regenerated catf control va-lve 51.. vThe"result'iirgf'mixture of .-oil

Y and solids-then passes through' conduit 32'to the reaction chamber 33,' of-construction-similar to reaction chamber 33 shownin Fig.'r I. "Theflovv of the mixture through the-reaction chamberand subsequent separating and. fractionatinggequipment is the same asfthat illustrated in Fig i-I.

In this'case, the-amount of hot catalyst 'introduced into the relatively cool oil stream'passing :through transfer line'l'' is-sufcient to heat the :,oil to thev desiredcracking temperature'an'dfto supply the necessary heatfor'the cracking process. 'Expressed' in vanother/Way, the amount of solid' material sc introduced is controlled to' ob- ."tain thedesired heating.-V Theactu'alamount of :fsolid material may beof the order of from y10 "partei-of. solid material per part"'ofoilvup'toi-l) or more parts of solidmaterial per part ofi-oil.

simplicity' 9.. For example, when cracking an East Texas re.- duced crude at4 a. temperature, ofr about. 9509 F. and regenerating the solid material ata temperature between 1150 F. Yand 1200? E., the amount. of solid material introduced into the oil stream will beof` the order of from 15 to20` parts @solid-per part of oil.. u A

. By comparing the amountof equipment shown.

in Fig. n with vthat iuustratedgin Fig. I.. it will catalyst mustbe added. tothe oi-l than is the case when. ai part of the heat issupplied by indirect heatexchange in heat exchangers 20.and 22. Expressed, in another way,` when operating without the h'eat exchangers 20 and 2-2 substantially all` of thev heat liberated during. regeneration, except that. taken out byA regenerating` gas, mustobe absorbed by the catalyst passing tothe feed oil; Consequently, when operating in thismanner the amount ofA hot. catalyst added to the oil must bev such that the amount. of catalyst employed. in

proportion to the amount of coke formed` in the; cracking zone issuicientto absorb substantially all the. heat liberated during regeneration.y In.v some cases the amount. of. catalyst necessary to. supply the heat requirements for the cracking'` processl mayresult-in excessive` catalyst lossegandcause. excessive cracking. resulting in the formation? of undesirable amounts. of lowgrade products,.lsuch as gas and. coke.. In.Y such cases a part of the catalyst may be` replaced by relatively inert heat absorbent materials such as` pumice, fullers' earth, bauxite, diatomaceous. earth, and-sand whichl have little if any catalytic inuence on the reaction. The amount of such inert solids may range from to 90% of the total solids circulated, depending upon a number of factors, such as the nature of feed stock, amount of coke formed, activity of the catalyst, temperature of cracking and of regeneration, rate of ycirculation and other factors. For example, when cracking an East Texas reduced crude at a temperature of 980 F. with acid-treated clay wherein about 5.5% of the'oil is converted to carbon which is retained on the solids, approximately 45 parts of solids heated to 1050 F. by regeneration will be required to preheat the oil from room temperature to final cracking temperature and for supplying the necessary heat for cracking. In such a case it will be desirable to replace a part of the catalyst with less expensive inert material. It will be understood, however, that by regenerating at a higher temperature or by employing feeds which produce less coke under a given set of conditions the amount of solids necessary. to supply the heat can be materially reduced. As a further example, when regenerating at 1150 F. rather than 1050 F. the amount of solids to supply the required heat may be reduced from 45 parts to about parts, other conditions being the same.

In some cases, the amount of heat liberated during the regeneration may be more than sufficient to carry out the cracking operation. In

1-0y such cases. a. portion of the.A oil4 afterl circulating. through. the heat,v exchangers 21). and. 22. may. be.- passed through line 'Il land. pump-1.8. te. an. addi. tional. heat.. exchanger 1.9,. which may be inthe form of a waste heat boiler.

The. oil.4 after passing, through; thef heat. ex-

changer lY i'sr transferred; through line. 8 to.. line. l andr is4 returned. to. the inlet side of.; heat.. ex-..

changers 2ll-andi2.2.. t y

The pressure. necessary. totransfer the catalyst from the regenerating chamber to the oil stream. inline. 32. is. developed.. accordingE to the/preferred. embodiment. ofi the invention., by.v con-.-

structing the. catalyst.conduitlllofvv such height.

that. the. combined height of the catalyst within the. regenerat'or. and. in: thev conduit. 30. sufli.-Y

cient to. build up. hydrostatic. pressure. somewhat in excess` of the. pressureon the oil; vapors atthe.-

point. of entry of I the-.'cata1yst. therein. Like-.

wise the pressure-necessary to. transfer the.- cat.-

alyst into.- ther regenerating gas.` stream in. line. 51. may.V be. developedv by constructing the. feed, conduit of aheightor elevationsufcient to. bui-1d,- up a hydrostatic pressure somewhat. inv excess: of. the. pressure. on` the` regenerating gasA4 atthe point. of entry ofthe'spent catalyst.v therein... This-will.- insure proper ow of. regenerating gas, and-oil.- and prevent. by-.passing of. oilinto. they regenerating` zone. and vice. versa. In. order. to. transmit the pressure` through the. standpipes or catalyst feed conduits, 30v andv 3.1. the.` catalyst. should bef maintained inafreely ovving state therein.l In some cases. anfluidizing, gasmay be introducedA at one or more spaced. points. along the conduitsto maintain the catalysty in, fluidized condition. It-

may also be. desirable. to. introduce. aV fluidizing gas at. all.' points the system. where. the,4 catalyst. is. segregated fromthe. gas. stream.k

Tofavoid. reducing and building4 up pressures. 010.I the. C2L3J5`-SI2v passing back andl forthffrom thev regenerating, chamber. to. the.. cracking chamber, it iS of advantage. to. operate, bothithe. cracking andthe. regeneration processi at. substantially.' the. same pressure levelexcept for the pressure drop, inherent inthe iiow,..'and.it.isfa1so of advantage. tomaintain the pressure drop through the system at a minimum so as to reduce the height of tubes 3i and 3i) employed for developing the required'pressure. The passageof the cracked vapors and regenerating gas through the cracking and regenerating Zones at a low Velocity as previously described, tends to reduce the pressure It will be understood that the height of the :feed conduits S and 3l does not depend on total pressure on the system but the pressure drop through the system and the pressure diierential between the cracking and regenerating zones so that any desired total pressure may be maintained in the circuit.

In some cases the amount of coke formed during the cracking operation may be insuiicient to generate the required heat during regeneration to preheat, vaporize and carry out the cracking process. In such cases, additional heat may be supplied to the regenerator either by external heating or by adding a combustible yfuel into the stream of regenerating gas. However, in most instances the amount of coke formed during the cracking treatment will be suiiicient for heating v the oil.

The present invention also contemplates `absorbing the excess heat formed during regeneration by admixing With the catalyst aV relatively ,inert inaterial capable of absorbing' substantial quantities of heat liberated during the cracking' process; ""ThisY inert adsorbentA materia1 can be utilized for carrying lheat from the regenerator 58 to the cracking'equipment.' Y Having described the preferred embodiment of the'invention, it will be understood that "it embraces such other variations'and modifications as come Within the spirit and scope thereof.l 'n

What is desired to be protected by Letters Patent" isz" ILInv a process of cat'alytically converting resid--A ual foils 1 containing constituents unvaporizable Without substantial decomposition into motor fuel wherein the oil is'oracked 1in the presence of aV solid adsorbent catalyst injsubdividedgform and the lcatalystfr egenerated Yat V a temperature higher than the cracking temperature; the method which comprises passing the residual oil to be cracked in'ii'direct heat exchange relation With'regenerated catalyst to thereby preheat said oil and cool saidrcataly'st, returning said cooled vregenerated `catalyst to the regenerating zone, mixing' saidoill temperature, the amount and temperature'v of the catalyst so introduced being Vsuiiifcient to heat said oil above VStill" F. and'completely absorb the uri.- vaporizable constituents contained therein Vt0 thereby form a relatively drysuspension Vof` il vapors and catalyst;niaintainingthe oil vapors n in contact with the catalyst 'within said cracking* zone for a periodsuicienttocrack at-'least30%A thereof into motorfuel constituents, conti-nvufously'-A separating a stream of finely divided catalyst'con-` taining solid combustible deposits from theoilva-j'V pors, thereafter fractionating" the oil vapors to segregate a motor fuel fraction therefromfen-L tinuously passing a stream of saidjcatalyst sep arated from said oil'vapors -into a regeneratingzone, passinga stream of oxidizing gasupwardly through 4said rzone at avelocity limited'toform a dense, turbulent bed of catalytic material and:

oxidizing gas in the bottom'sectionoffsaid regenerating "zone,y burning combustible deposits from the nely divided catalyst Within saidregeneratv Vingzone to thereby heatsaid catalyst to a temwith regenerated"cata1yst1vvhile saidcatalyst is at substantially the regenerating temperature,

adding sufiic'ientcatalyst to said oiltosupply al1 Y lof then/additional 'heat necessary for crackingsaid Io'il and completely adsorb al1 oil constituents re-j `maining unvaporized at the mixing temperature, passingithe resulting mixture through a crack' ling zone, maintaining said oil vapors Within said cracking zone to obtain the desired cracking thereof,VV separating the cracked products from the catalyst and -fractionating the cracked produots `toy segregate the desired fraction therefrom. 2. 5A process for the catalytic cracking of heavy residualoils containing ar substantial portion of constituents unvaporizable Without decomposi- 1tion tofform lower boiling hydrocarbons inthe `motor-fuelV boiling range Whichcomprises passing a stream of said residual oil through a cracking l zonel introducing a stream of'hot regenerated cat- 1 alyst While said catalyst is at substantially regenerating temperature 'into said stream of oil while l said oil vis at a temperaturebelow active cracking perature "above the temperature maintained in said cracking zone but below the deactivation temperature of said catalyst, the density'and turbulence of the catalyticA material Within said regenerating zone being sucient to maintain a:

substantially iuniform temperature throughout'- they regenerating zone, continuously withdrawingA a stream of regenerated catalyst from the regenerating zone and continuously returning said catalyst to said oil stream while at substantially its catalyst therein and maintaining the catalyst within said column in a free flowing i'luidized n state. '1

' l HOMER Z.

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