CA1075628A - Conversion of hydrocarbons with "y" faujasite type catalysts - Google Patents
Conversion of hydrocarbons with "y" faujasite type catalystsInfo
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- CA1075628A CA1075628A CA218,364A CA218364A CA1075628A CA 1075628 A CA1075628 A CA 1075628A CA 218364 A CA218364 A CA 218364A CA 1075628 A CA1075628 A CA 1075628A
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- catalyst
- riser
- hydrocarbon
- zone
- conversion
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Abstract
CONVERSION OF HYDROCARBONS WITH "Y"
FAUJASITE TYPE CATALYSTS
Abstract of the Disclosure The specification discloses a variety of schemes whereby a riser cracking unit processes both a gas oil feed and a supplementary C3 and or C4 hydrocarbon feed, applying different conditions to each feed to yield a composite product of enhanced quality. The catalyst is faujasite-containing, and a common or separate risers may be employed for the two feeds, with or without catalyst regeneration between processings.
FAUJASITE TYPE CATALYSTS
Abstract of the Disclosure The specification discloses a variety of schemes whereby a riser cracking unit processes both a gas oil feed and a supplementary C3 and or C4 hydrocarbon feed, applying different conditions to each feed to yield a composite product of enhanced quality. The catalyst is faujasite-containing, and a common or separate risers may be employed for the two feeds, with or without catalyst regeneration between processings.
Description
6;~3 The present -Lnvention relates to the production o~ gasoline by conversion of hydrocarbons in the pre~ence o~ a ~au~asite-containing catalyst.
The invention is concerned with more completely exploiting the activity and selectivlty o~ "X" and "Y"
faujasite crystalline aluminosilicate conversion catalyst to upgrade both gas oil feed materials and normally gaseous hydrocarbon products such as those obtained from a gas oil conver~ion oper~tion, namely C3 and C4 rich hydrocarbon ga~eous material. The C3-C4 material may be obtained from other a~ailable refinery sources. The gas oil boiling range hydrocarbon feed may be a residual oil or a hydrogenated product thereof.
Accord~ng to the present invention a process for producing gasoline by riser conversion of gas oil under ~-~crack1ng conditions, employing an inventory of flu~dized, ~aujasite-containing cracking catalyst is characterised ~ by the ~act that catalyst ~rom said inventory is slmultaneously s employed, under condltions different ~rom gas oil cracking conditions, for riser conversion o~ an independently intro-duced ~eed comprising C3 and/or C4 hydrocarbons and that single product stream containing the products o~ both sald riser conversions is taken of~. The independently introduced ~eed may comprise predominantly isobutylene~
and the catalyst prererably comprises rare earth exchanged zeolite Y.
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In a preferred embodiment both conversions are effected in a single riser, wherein the C3 and~or Cl~ hydro-carbon feed contacts freshly regenerated catalyst at the bottom o~ the rlser and the gas oil is fed to the riser downstream. In such embodiment the gas oil advantageously contacts the catalyst at a temperature of 950 to 1100F
; at a catalyst-to-oil ratio in the range of 4 to 10, whilst khe C3 and/or C4 hydrocarbon feed advan~ageously contacts the catalyst at a temperature of about 12504F and a residence kime of 0.1 to 2 seconds - In an alternative embodiment the conversions are e~fected in separate risers which discharge catalyst into a common catalyst settllng zone, optionally through a separator. Both risers may be supplled with ~reshly regenerated catalyst, but alternatively the riser in which gas oil is converted is fed with freshly re~enerated catalyst, that in which C3 and/or C4 hydrocarbon is converted is fed with catalyst withdrawn ~rom said setkling zone. The gas oil is preferably converted at a temperature o~ at lea~ g50F. and a residence time of 2 to 10 ~econds, whllst the C3 and/or C4 feed ls preferably converted ak a tempera~ure of 700 to 1100F, a catalyst-to-feed ratlo o~
~5 to 10 and a residence time of 1 to 10 seconds. In a variation of this embodiment the riser in ~qhich the C3 and~or C4 feed 1~ converted is wholly contalned wlthln a vessel the lower portion of which constitutes said settling zone, which riser is applled wlth catalysk ~rom sald zone.
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1~7~i6Z8 In accordance one preferred embodiment of this inventlon, a C3-C4 rich hydrocarbon mixture or an isobutylene rich stream is contacted with the "Y" faujasite conversion catalyst before contact with gas oil boi].ing range feed material S in an initial portion of the riser or aft;er initial contact with gas oil ~eed. The gas oil conversion is accomplished at a catalyst to hydrocarbon feed ratio in the range of 4 to about 10 and an elevated hydrocarbon ~eed tempera-ture sufficient to ~orm a suspension at a temperature in the range o~ about 950 to about 1100F. Con~ersion of the C3-C4 rich hydrocarbon feed, on the other hand, is accomplished at temperatures above that relied upon for gas oil cracking or lmder lower temperature gas oll conversion temperatures. Thus the C3-C~ hydrocarbon ri.ch feed which may be charged to the riser to encounter the regenerated catalyst at its highest temperature received from the regeneration zone may be converted at a temperature o~ -about 1250F before the suspension thereo~ is brought ln contact wlth gas oil feed ln the riser. Therefore, the residence time o~ the C3 C4 hydrocarbon rich ~eed at high temperature conditions be~ore gas oil contact may be up to 1 or 2 seconds or it ma~ be only a ~raction of a ~econd, as llttle a~.one-tenth of a ~econd, but the contact time under lo~er temperature conditions may be equal to or greater than , t.hat employed ~or the gas oil conversion operation. In any z5 e~ent, the convFrzion zone 1s mainta1ned under cond1t1onz , :
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' ,-' ' ~4-' ~7S6;~8 whiçh can provide a hydrocarbon residence t~me within the range o~ 1 to about 12 seconds before sepa,ration o~ the ~u~penslon. This is BO sinc~ elther one o~ the feed~ may be ~ntroduced to the ri~er conver~ion zone. at ~paced apart intervals lying in a downstream portion thereof. During this combinatlon conver~ion operation9 the "Y~ ~au~a~ite catalyst provides hydrogen trans~er activity and c~cliæation ~lectivity which converts introduced and ~ormed C3-C~ hydro~
carbon~ to aromatics, alkyl aromatics and some low bo1ling gaseous material.
The C3_C~ rich hydrocarbon feed materlal or the isobutylene rlch feed may be separately ~urnace heated or heated by other suitable means to a temperature suitable for introduclng to the riser convers~on zone. The C3-C4 rlch hydrocarbon ~eed ~nitially contacting the freshly regenerated catalyst may encounter signiflcantly di~erent hlgh t~mperature residence times depending upon whether the ga~ oil i~ introduced to an inltlal, intermediate or down-stream portion of the r~ser conversion æone.
Cataly~t particles separated ~rom the conversion ~on~ are Btripped in a ~tripping zone countercurr0nt to rl~ing stripplng ~a~ such a~ ste&m as ment~oned above. The ~tripped catalyst is then transferred to a cataly~t regeneration z~ne not shown for the removal o~ depo~ited carbonaceou~
makerial b~ bu~ning thereby heating the catal~st to an elevated ~ temperature ln tha range of 1150F. up to 1500 or 1600Fo -' . ~"
_5_ ~756Z8 In a ~urther ~avoured embodiment o~ the invention a second separate riser reactor discharging into a catalyst separation zone such as one or more cyclonic separators is provided wherein catalyst particles are separated ~rom hydro-carbon vapors and thereafter stripped in the same or a dif~erent stripping zone than that used ~or strlpping catalyst separated ~rom the gas oil riser conversion operation. In accordance with this embodiment the strlpped catalyst separated from each riser conversion zone may be passed to a common regeneration zone or all or a portion of the catalyst separated ~rom the gas oil riser conversion zone may be cascaded to the second separate riser reactor wherein it is contacted with a gaseous stream rich in C3-C4 hydrocarbons. In this arrangement the catalyst separated from the gas oil conversion step generally at an elevated temperature of at least 900F is available for ~low upwardly through a second separate riser conversion zone cuspended in normally gaseous C4 and lower boiling ~eed material.
~n this invention, a C3-C4 rich h~drocarbon mixture or an iso-butylene rich feed material i~ combined with ~reshly regenerated "Y" fau~asite conversion catalyst or that separated and cascaded ~rom the ~as oil conversion zone under conditio~s to provide a catalyst to h~drocarbon ~eed ratio in the range o~ 5 to about 40 ~ at an ele~ated hydrocarbon ~eed temperature su~icient to ~orm a -~ suspension at a temperature in the range o~ about 900F to about ,25 ~ 1100Fq The normall~ gaseous hydrocarbon-catalyst suspension '~ passes upwardly through the second riser conversion zone under conditlons providing a h~drocarbon residence time within the ~, ; range o~ 1 to about 10 seconds be~ore separation o~ the suspension.
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Durlng this operation~ the "Y" ~au~asite catalyst comprising hydrogen trans~er activity and cyclization selectivity convert~
the C3-C4 hydrocarbons -to aromatics, alkyl aromatics and low boiling gaseous material.
Catalyst particles separated from the conversion zones herein de~ined are caused to ~low downwardly to and through one or more stripping zones countercurrent to rising stripping gas such as steam. The stripped catalyst is then tran~ferred as above provided or to a catalyst regeneration zone not shown for the removal of deposited carbonaceous material thereby heating the catalyst to an elevated temperature.
In yet a further advantageous embodiment o~ the invention, a restricted or relatively short riser reactor discharging into the catalyst separation means such as one or more cyclonic separators at the riser outlet is provided within the upper portion of the enlarged vessel so that the restricted rise~ extends upwardly ~rom within the collected bed of catalyst to an upper portion of the vessel. In thiæ
arrangement the catalyst separated from the gas oil conversion step at an elevated temperature is available ~or ~low upwardly through the re~tricted riser conversion zone suspended in normall~ gaseous C3-C4 hydrocarbon feed material. In this inventlon~ a C3-C4 rich hydrocarbon mixture is combined with faujasite conversion catalyst separated from the gas oil conversion zone at an elevated cracking temperature to ~orm a ~uspension o~ catalyst to hydrocarbon feed ratio in the range of 5 to about 40 at an elevated suspension temperature in the range of about 700 to about 1050F~ The C3-C4 rich hydrocarbon ~eed stream may be furnace heated to an elevated temperature 1n the range o~ 550F to about 900F be~ore ~L~75~Z~
entering the restricted riser conversion zone. On the other hand, to vary the catalyst to hydrocarbon ratio within the restricted riser conversion zone, steam may be used along with the C3-C~ hydrocarbon stream. Also steam may be used to e~fect the li~t characteristics o~ the suspension to pass upwardly through the restricted conversion zone. The suspension formed as herein provided passes upwardly through the restricted riser conversion zone under conditions providing a hydrocarbon residence time within the range of 1 to about 10 seconds before discharge and separation o~ the suspension by cyclonic means.
During this operation~ the ~au~asite catalyst providing hydrogen trans~er activity and cyclization selectivity converts the C3-C4 h~drocarbons to aromatics; alkyl aromatics and low boiling gaseous material.
Catalyst particles separated from the conversion zones herein identified are caused to ~low downwardly to and through a stripping zone countercurrent to rising strlpping -~
gas such as steam. The stripped catalyst is then transferred to a catalyst regeneration zone not shown ~or the removal of deposited carbonaceous material thereby heating the catalyst to an elevated temperature It is contemplated providing separate stripping - zone~ ~or stripping cat~lyst separated from each rlser con-i .
~ version zone and adding heat to each strlpping operation.
~or ex~mple, either one or both stripping operatlons may be ; pro~ided with hot regenerated catalyst to raise the temperature o~ the stripping zone. On the~other hand~ where a single ; stripping zone is used~ it may also be advlsable to bring ~ ~ stream o~ hot re~enerated catalys~ into the ~tripping operation to maintain lts e~icienc~ at a high value.
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It is also contemplated passing the relatively cold catalyst o~ the C3-C4 hydrocarbon conversion step to a lower portion of the gas oil separated catalyst stripping step and providing multiple stripping gas inlets to the stripping æone.
. ~ The invention will now be illustrated with re~erence to the accompanying drawings, in whlch:
Figure I is a diagramrnatic sketch in elevation o~ an embodirnent of the invention employing a single riser;
Figure 2 is a diagrar~matic sketch in elevation ) of an embodiment of the invention employing separate risers .~or convers'Lon o~ the two feeds, each supplied with regenerated catalyst;
Figure 3 depicts an embodiment similar to that of Figure 2, dif~ering there~rom in that the arrangement j is modi~ied to cascade catalyst, without regeneration, ~rom the first riser to the second5 and Figure 4 iB a diagrammatic sketch in elevation o~ that embodiment of the invention wherein a second riser : :
is enclosed within a vessel, the lower part of which serves ;) a~ catalyst settling'zone~
Throughout the drawings, like numerals designate like parts. .
D~.SCUSSION OF SPECIFIC EMBODIMENTS
Principal Embodimen~ A.
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Referring now to Figure I, there is shown a riser conversion zone 2 supplied with hot regenerated catalyst by j conduit 4 provided with a catalyst ~low control valve 6.
Steam i~ 'Lntroduced to a bottom portion o~ riser 2 by one or more steam inlet conduits 8 and/or 10 and a gas oll. ~eed is introduced by inlet condult 12 whlch pro~ects upward:Ly ; lnto the bottom portion of riser 2. A C3-CL~ rich hydrocarbon .~.
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~75~;21!3 ~raction may be introduced separately or wlth steam by conduit 8 to the bottom portion of rlser 2 for adm~xture with hot regenerated catalyst. A suspension of catalyst in up~low gasiform hydrocarbon material with or without steam provides a mix temperature of at lea~t 1100F initially ~ormed and passed upwardly through an annular section o~ riser 2 about a gas oil inlet means 12 under velocity conditions selected to provide a hydrocarbon residence time as low as about one-tenth of a second up to about 1 or 2 seconds. The upflowing initially ~ormed suspension in the annulu~ of rlæer 2 is thereafter combined with preheated hydrocarbon feed such as a gas oil ~eed introduced by conduit 12 pro~ecting upwardly into the bottom of riser 2. The thus formed suspension at an elevated cracking temperature of at least 1000f is caused to ~low upwardly through the remaining portion of the riser under hydrocarbon conversion conditions. On the other hand, the gas oil ~eed may be introduced at spaced intervals along the riser as by condiuts 14 and 16. In yet another embodiment it is contemplated initially li~ting the hot regener~ted catal~st ~20 with steam or other i~ert gas before contact with the gas oil ~eed lntroduced by conduit 12 ~or upward ~low through the riser, Additional gas oll feed may also be added downstream to the thus formed suspension. Thereafter gaseous hydrocarbons rich in C3-and C4 hydrocarbons are introduced to the upflowing suspension by conduit 16 or a ~urther downstream Lnlet conduit not shown permitting a minimum residence time o~ about 1 second ~or low temperature upgrading as herein described. In the arrangement o~ Figure I, the suspeD6ion in riser 2 is clischarged into cyclon$c separatlon zones 18 and 20 hou~ed in the upper , ., : , ,, , --10--7~6~3 portion of vessel 22 wherein separation o~ catalyst .from hydrocarbon vapors is accomplished. Hydrocarbon vapors .separated from catalyst then pass into a plenum chamber 24 ~or removal ~rom the vessel by condult 26. Catalyst separated ~rom hydrocarbon vapors in cyclonic means 18 and 20 pass by diplegæ 28 and 30 to a fluid bed of catalyst 32 maintained in the lower portion of the vessel 22. The fluid bed o~
: catalyst 32 is in open communication with a lower extending stripping zone 34 therebelow to which -the ~luid bed of catalyst moves generally downward countercurrent to rising stripping gas introduced by conduit 36. The stripping zone is maintained at a temperature within the range of 900F to 1150F and the higher temperatures may be ~acilitated by the addition o~ hot regenerated catalyst to the catalyst in the stripping zone by means not shown.
Stripped catalyst i8 removed from a bottom portion o~ the stripping zone by conduit 38 for trans~er to a catalyst regeneration zone not shown~ Stripped catalyst may also be recycled to the riser inlet by conduit means not shown . when it is desired to provide catalyst to hydrocarbon ratios greater than 20 and as high as about 80~
The fluid bed o~ catalyst 32 separated ~rom the riser conversion zone 2 is at an elevated temperature and may be in the range of ~rom about gO0F to about 1100~.
As suggested above, gaseous hydrocarbon feed such as a mixture o~ C3-C4 hydrocarbons may be used to form a high te~perature suspension in a bottom portion o~ riser 2 by use of either ~onduit 12 or 8 alone or in combination with one another before gas oil is lntroduced to a downstream portio~ of riser 2 as by one or both of conduits 14 and 16.
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Also3 as a means for controlling catalyst to hydrocarbon ratios in the riser an inert gas may be initially employed to form a suspension in a bottom portion of the riser into which C4 and lighter hydrocarbons and gas oil are dispersed as herein provided. The suspension formed will vary consid-erably in temperature as herein provided and in catalyst/
- hydrocarbon ratio but generally will be in the range of 10 to about 40.
The method and ystem of Figure I above described may be modlfied considerably in opera-ting combinations without departing from the concepts of the present invention. In addition to the embodiments above identified~ riser 2 may be substantially e~ternal to vessel ~2 and stripping zone 34 rather than pass upwardly through substantiall~ the center thereof In this arrangement, the riser relied upon to upgrade C4 and lower boiling hydrocarbons and gas oil may be provided with additional hot freshly regenerated catalyst in ~ downstream portion of the gas oil riser con~ersion section.
In one or more of the above defined embodiments, the C~ and lower boiling gaseous feed components contact acti~e conversion catalyst o~ the faujasite type at a temperature within the range o~ 700F up to about 1100F and the gas oil ~eed contactæ
the fau~asite catalyst preferably at temperatures in excess o~
900F and as high as 1100F. In yet a further embodiment it 25 : i5 contemplated employing a riser system in whLch the gas oil feed inltially forms a high temperature catalyst/oll suspenslon in the bottom annular portion of the riser about inlet conduit 12 through which dispersion steam is introduced, additional gas oll feed may be added to the suspension as by condult 14 and a C4 rlch ~tream may then be added to the up~lowing suspension as by conduit 16. In other words, lower boiling gaseous , _. . .. _ _ ._.. . . ._ .. . .. ,.. ., . .. .... . .. . . . . . . . . .. .. , ., . __, .. __, . __ ~7~Z~
hydrocarbons such as a C3-C4 rich stream is brought in con-tact with the gas oil-catalyst suspension in a downstream or upper portion of the riser conversion zone.
Principal Embodiment_B
Referring now to Figure II, there is shown a riser conversion zone 92 supplied wi~h hot regenerated cata-lyst by conduit 94 provided with a catalyst flow control valve 96. Steam is introduced to the bottom of riser 92 by one or more steam inle~ conduits 98 and about a gas oil inlet conduit 100 which projects upwardly into the bottom portion of riser 92. A suspension of hot freshly regenerated catalyst in upflowing gas oil and steam provides a mix temperature of at least 950F. which is passed upwardly through the riser 92 under velocity conditions selected to provide a hydrocarbon residence time within the range of 2 to about 10 seconds.
The upflowing suspension in riser 92 is discharged from the end thereof into a separation zone, shown in the drawing, to house one or more cyclonic separation zones.
On the other hand, riser 92 may discharge dir-ectly into one or more cyclonic separating means, as shownin Figure III discussed below, for separating fluid catalyst particles from hydrocarbon vapors.
In the arrangement of Figure II the suspension in riser 92 is discharged through slotted openings at the riser outlet into an enlarged se~tling zone of reduced fluid stream ve}ocity or vessel 102 wherein separation o catalyst from hydrocarbon vapors is encouraged by a substantial reduction in the suspension velocity. Hydrocarbon vapors then pass through cyclonic separation means 104 for removal of ~;
entrained fines before the hydrocarbon vapors pass into a plenum chambex 106 and removal from the vessel by corlduit 108.
, ~j ' ' ~756~3 Catalyst separated from hydrocarbon vapors by settling and in cyclonic means 104 pass to a fluid bed of catalyst 112maintained in the lower portion of vessel 102. The fluid bed o~ catalyst 112 is in open communication with a stripping zone 114 therebelow through which the fluid bed of catalyst moves countercurrent to rising stripping gas introduced by conduit 116. Stripped catalyst is removed from a bottom portion of the stripping zone by conduit 118 for transfer to a catalyst regeneration zone not shown. The fluid bed of catalyst 112 separated from the riser conversion zone 92 is at an elevated temperature in the range of about 800F. ~o about 1000F.
A second separate riser conversion zone 120 is provided in parallel arrangement with riser 92 which also discharges into an upper portion of vessel 102. Risers 92 and 120 are preferahly positioned within vessel 102 at least at their discharge end so that a suspension of catalyst and hydrocarbon vapors is discharged substantially adjacent the inlet of cyclonic separation means within the vessel. A
gaseous hydrocarbon feed such as a mixture of C3-C4 hydrocarbons or a C4 rich fraction is introduced to the bottom inlet conduit 126 of riser 120 for admixture with hot reg~nerated .
catalyst particles in condu~:t 124 to form a mixture or sus-pension at a temperature within the range o~ 700~F. to about 1100F. The suspension formed in a catalyst/oil ratio in the range of 5 to about 40 is passed upwardly through riser 120 under conditions to provide a hydrocarbon residence time within the range of 1 to about 10 seconds. The upwardly flowing sus-pension in riser 120 is discharged in the speci~ic arrangement oi Figure II from the upper end thereof through slots provided into the enlarged settling section of vessel 102. rrhe discharged suspension is separated by catalyst settling induced by a " ~
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drop ln the suspension velocity and by the aid of cyclonic ~eparat~on means such as cyclonic means lt)4. The separated catalyst i~ returned to the ~luid bed of catalyst 112. The discharge end of riser 120 may also be provided with one or more cyclonic separation mean~ BO that the auspension pa~sed ~pwardl~ through the riser will pass directly into the cyclonic separator~ rather than pass f~rst into the enlarged ~ettllng ~ -zone and then through cyclonic ~eparatlon means.
Principal Embodiment C
In the ar~angement of Figure III a gas oil ~;
conversion riser 40 is charged in a bottom portion thereof with gas oil by conduit 42, steam by conduit 44 and hot freshly regenerated catalyst by conduit 46 to form a sus- . :
pension at an elevated cracking temperature of at least about 1000F. The suspension formed is passed through the rl~er under condition6 to provide a hydrocarbon residence time ;
ln the range of 2 to 10 or more seconds be dlscharged ~rom th~ riser dlrectly into a c~clonic separation zone 48. Cataly~
particles separated from-hydrocarbon vapo~s in zone ~8 are pa~sed by dipleg 50 to a bea o~ cataly~t 52 in a stripping zon~ therebelow, Hydrocarbon vapors separated from cataly~t ~n zone 48 are conveyed to a collecting zone 54 or plenum ch~mber in the upper portion o~ vessel 56 before removal .
therefrom by conduit 58.
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atalyBt bed 52 is conflned within a stripping -~ection ln the lower portion o~ ve~sel 56 and i~ ad~acent to .. .
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a ~econd bed of catalyst 60 but separated there~rom by ~
~ubstantiall~ vertical baffle 62. Ba~fle 62 is provided in an upper portion thereof with a plurality of catalyst trane~er slots 64 for trans~errin~ catalyst from bed 52 to bed 60 as more ~ully discussed below. The catalyst ln bed 52 at an elevated temperature in the range of about 900F. to about 1000F. m~y be ~urther temperature elevated by adding hot r~generated catalyst directly to the bed. Catalyst bed 52 moves generally downward and countercurrent to rising stripping ga~ introduced by conduit 66. Stripped catalyst at an elev~ted temperature in the range o~ 850F. to about 1000F. i~ removed by conduit 68 and pa~sed to the bottom portion oP a second . riser conversion zone 70. Steam is introduced to a bottom por~ion o~ riser 70 by conduit 72 and normally gaseous hydro-carbons comprising C4 and lighter hydrocarbons are introduced by conduit r4. A suspension o~ catalyst in normally gaseous hgdrocar~ons and steam is ~ormed which then moves upwardly through riser conversion zone 7G at a tem~erat~re ~rithln the range o~ 800FQ to abou~ 1050F. under veioclty conditions pro~iding a hydrocarbon residence time in the range o~ 5 to ; 15 ~econds~ The suspension passin~ithrough rlser 70 ls dischar~ed in this arr~ngement directly into a cyclonic se~aration zone 76 wherein hydrocarbon vapors are separated ~rom catalyst particles. The hydrocarbon vapor~ and steam ~ pa~s overhead to plenum ch~mber 54 for admixture wlth hydro-carbon products o~ ga~ oi~ cracklng, Cataly~t separated ~n ~one 76 ls conveyed by dipleg 78 to fluld catalyst bed 60.
Catalyst bed 60 will normally be at a lower temper~ture than i ~75~
~ed 52 but thls can be remedied to some ~xtent by conveying catalyst particles through slots 64 in baffle 62 from bed 52 to bed 60~ A1BO~ lt is contemplated adding hot freshly regenerated catalyst to bed.60 to ad~ust the te.~peratur~
~; 5 thereo~ to a de~ired elevated temperature of at least 850~F, and prP~erably at least 950F. Catalyst bed 60 moves -generally downward through lts strippin~ section counter-current to stripping gas introduced by conduit 80. Stripped catalyst r~moved-from the bottom of bed 60 is then conveyed ~ ~.
by conduit 82 to a regeneration zone not shown.
Stripped products and strlpping gas ~eparated from the upper surface of beds 52 and 60 pass through cyclonic aeparating means represented by 84. Gasiform materl~
compri~ing stripping gas separated from entrained catalyst !5 fines pa~s from separator 84 to plenum 54. Separated cataly~t f~nes ~re pas~ed by dipleg 86 to bed 60.
It i~ to be understood that cyclonic separating 48, r6 and 84 may each be a plurallty of interconnected ~eparation zones pre~erably arranged ln sequence to provide ~ :
~0 more than one stage of cyclonic separatlon in the recovery ` : .
of cataly t ~ines from vaporouB hydrocarbon materlal a~d - strlpp~ng gas.
In yet ~nother embodlment, it is contemplated modi~ying the arrangement of either FigureII orIII to u8e ~5 low boiling ga~eous hy~drocarbons such as isobutylene or a miæture of C4 and lower boiling hydrocarbons as a fluidizing gaB lnstea~ of steam introduced to the bottom portion of the :-" gas oil riser conversion zone as by conduits 98 (Fig. II) and : 1 44 (Fig. IV~.
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On the other hand, steam is a desirable fluidizing medium for use in riser conversion zones 120 (Fig. II) and 70 (Fig.
III) since it may be used to alter or adjust the catalyst/
hydrocarbon ratio in these trans~er conversion zones using the C3-C4 hydrocarbon stream as the primary feed.
Principal Embodiment D
Referring now to Figure IV, there is shown a riser conversion zone 202 supplied with hot regenerated catalyst by conduit 204 provided with a catalyst flow control valve 206. Steam is introduced to a bottom portion of riser 202 by one or more steam inlet conduits 208 external to and about a gas oil inlet conduit 210 which projects upwardly into the bottom portion of riser 202. A suspension of cat-alyst in dispersion steam is thus initially formed into which an upflowing gas oil feed is introduced providing a mix or catalyst-oil suspension temperature of at least 950F. Steam may also be combined with the oil charge. The suspension passes upwardly through riser 202 under velocity conditions selected to provide a hydrocarbon residence time therein preferably within the range of 2 to about 10 seconds. The upflowing suspension in riser 202 is discharged from the end thereof as by slotted openings into an enlarged catalyst settling zone promoted by reduced vapor velocity. On the other hand, riser 202 may discharge directly into one or more cyclonic separating means or immediately adjacent the bell mouth opening thereto for separating fluid catalyst parti-cles ~rom hydrocarbon vapors.
The suspension in riser 202 is discharged into an enlarged zone or vessel 212 wherein separation of cata-lyst from hydrocarbon vapors is encouraged by a substantial ~75~
reduction in the suspension velocity. Hydrocarbon vapors then pass through cyclonic separation means 214 for re-moval of entrained fines before the hydrocarbon vapors pass into a plenum chamber 216 and removal from the vessel by conduit 218. Catalyst separated from hydrocarbon vapors by settling and in cyclonic means 214 pass by diplegs 220 to a fluid bed of catalyst 222 therebelow maintained in the lower portion of the vessel 212. The fluid bed of catalyst 222 is in open communication with a lower stripping zone 224 to which theifluid bed of catalyst moves downwardly to and through countercurrent to rising stripping gas intro-~uced by conduit 226. Stxipped catalyst is removed ~rom a bottom portion of the stripping zone by conduit 228 for trans-fer to)a catalyst regeneration zone not shown. A portion of the catalyst withdrawn by conduit 228 may be recycled to the inlet of riser 202 when a higher catalyst to oil ratio is desired. The fluid bed of catalyst 222 separated from the riser conversion zone 202 is normally (in the absence of restricted riser 230) at an elevated temperature and from about 25F. to about 75~. below the temperature employed at the inlet of the riser conversion zone 202.
A second restricted riser conversion zone 230 is provided within vessel 212 and the presence of such a restricted conversion zone will cause a further reduction in the catalyst bed temperature unless augmented as herein provided. Riser 230 extends from beneath the upper interface -I .. ".".. ..
of bed 222 into an upper portion of the vessel so that a suspension of catalyst and hydrocarbon vapors discharged Er~m the upper end of riser 230 will be substantially adjacent the inlet o~ a cyclonic separation means or discharge dir-ectly into cyclonic separating means. Catalyst separated ,i, ,",i ~
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as by cyclonic means 214 is then returned to a lower portion of bed 222 than the inlet to riser 230 by a dipleg 220 as shown. A catalyst withdrawal well about the inlet of riser 230 may be provided. A gaseous hydrocarbon feed such as a mixture of C3-C4 hydrocarbons at a suitable elevated tem-perature is introduced by conduit 232 with or without steam introduced by conduit ~34 to the bottom of riser 230 with suspended catalyst particles from fluid bed 222 to form a mixture of suspension at a temperature within the range of 700F. to about 1050F. me suspension formed in a catalyst/oil ratio in the range of 5 to about 40 is passed upwardly through riser 230 under conditions to provide a hydrocarbon residence time within the range of 1 to about 10 seconds. The upwardly flowing suspension on riser 230 is discharged from the upper end thereof adjacent the inlet to cyclonic separation means or directly into cyclonic separating means on the riser outlet and positioned in the upper portion of the enlarged settling vessel 212.
The discharged suspension is separated by catalyst settling in this embodiment due to a drop in vel-ocity and by the aid of cyclonic separation means such as separators 214. The separated catalyst is returned to the fluid bed of catalyst 222 by diplegs provided. The dis-charge end of risers 202 and 230 may be in a "T" connection and provided with one ox more cyclonic separation means on each end thexeof so that the suspension passed upwardly through the risers will pass directly into the cyclonic separators. This method of handling the suspension clischaxged from the risers provides a more positive control on the contact time between hydrocarbon vapors and catalyst parti-cles.
, ~75~z~3 :
The method and system of Figure IV above described may be modified to some considerable extent with-out departing from the concepts of the present invention.
For example, riser 230 may be a separate :riser, the major portion of which lS external to the vesse:L 212 in much the same manner as riser 202 is external to the vessel. In ; this arrangement, the riser relied upon to upgrade C4 and lower boiling hydrocarbons may be provided with hot freshly regenerated catalyst or catalyst separated from the gas oil riser conversion step either before or after stripping thereof. In yet another embodiment, it is contemplated initially contacting freshly regenerated catalyst in the bottom portion of riser 202 with a C3-C4 hydrocarbon rich mixture to form a suspension and thereafter bringing the ~.
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~7~62~3 suspension in contact with gas oil feed material in an upper portion of the riser at one or more spaced lnter~als be~ore discharg~ thereof into ca~alyst-hydrocarbon vapor separating zones. In one or more o~ the above embodiments, the C4 and lower bolling gaseous feed components may contact actlve conversion catalyst o~ the ~au~asite type at a temperature .
within the range of 800F~ up to about 1100F. and the gas oil feed may contact the catalyst preferably at temperature~
ln excess o~ 900F. and as high as 1100F. In yet a further embodiment it is contemplated employin~ a single riser system in which system the gas oil ~eed initially contacts the hot ~re~hly regenerated catalyst and a stream of C4 and lower boiling gaseous hydrocarbons such as a C3-C4 rich ~tre~m i~
'~ then brought in contact with the gas oil catalyst suspen6ioni 15 ~ in a down-stream or upper portion of the riser conver~ion zone. In yet another embodlment it ls rontemplated providing :. ~ an ~nnular conversion zone about an upper extension oi the ~tripping zone arranged so that stripped hydrocarbons will .
bypass the catalyst ln the annular con~ersion zone but all o~ th~ c~t~lyst~ di~charged from the ~iser con~ersion zone will pas~ into the annular conversion zone before entering . the ~tr1pping zone. In ~hi~ arrangement the feed to either : ~ the rl8er or a~nular conver~i~n æone may be either ga~ oil , ~: or a C3-C4 rich hydrocarbon streamO
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SPECIFIC EXAMPLE
A ~eries of conver~ion runs with an isobutylene rich ~eed were made under selqcted temperature and h~d~ocarbon re~idence time conditions whlch simulate the operations contemplated by the present lnvention and variations thereon.
A catalyst compri~ing 15% REY wa~ contacted under the conditions ldentified ~n the table below which produced the results identified. It was observod upon examination.o~ the product that a conslderable amount o~ hydrogen tr~nsfer occurred along w~th the production o~ a signi~icant amount o~ liquld product.
m e liquid product was identi~ied as consistlng chie~ly o~
toluene, xylenes~ trimethylbenzenes and naphthale~es, Runs were made at a temperature o~ 1050F. and 850F. using a wide spread in h~drocarbon re~idence time. The operating condition~
selected thu~ support the variations in operating arr~ngements contemplated by this invention without inter~ering with prior art operating c~ndltions such as those relled upon for : ~ con~arting a gas oil charge under elevated temperature cracklng conditions.
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~7~6Z8 It ~ill be observed from these data, that at the ~horter resldence time used for the riser conver~ion run~, cracking of Lsobutylene to lowe~ molecular welght gases and to coke i8 much reduced, However, at total converslon levels of 82.6, 6708 and 90.9% of tha i~obutylene~ los~es to un-: de~irable products are 12.21~ and the ratios of isobutane to butylene plus propylene ranga from l,15 to 3 0 25, Thus run 195 ef~ected at a high temperature and ~hort re~idence time supports the c~ncept of the pr~ent invention where the hot ~reshly regenerated catalyst~ cont~ct the C3-C4 r~ch feed initially in either a separate riser reactor or in an lnitial portion of a single ri~er reactor ~ollowed by gas oll cracking. On the other hand~ run 196 supports that portion of the concept of thi~ inven-tion wherein a previously used catalyst i~ contacted ln a separate rlser reactor or in a down-stream portion of a single gas oil riser reactor with the C3-C~ rich gaseoue hydrocarbon feed --material. Thus in any o~ these arrangement~ a "Y" fau~a~lte convbrsion catalyst has act1vit~ and selectivity for hydrogen t~Qns~er reaction and ole~in cycliæation reaction leading to the pro~uction o~ ~igni~icant quantitie~ of lsobutane ~nd aromatic~.
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The invention is concerned with more completely exploiting the activity and selectivlty o~ "X" and "Y"
faujasite crystalline aluminosilicate conversion catalyst to upgrade both gas oil feed materials and normally gaseous hydrocarbon products such as those obtained from a gas oil conver~ion oper~tion, namely C3 and C4 rich hydrocarbon ga~eous material. The C3-C4 material may be obtained from other a~ailable refinery sources. The gas oil boiling range hydrocarbon feed may be a residual oil or a hydrogenated product thereof.
Accord~ng to the present invention a process for producing gasoline by riser conversion of gas oil under ~-~crack1ng conditions, employing an inventory of flu~dized, ~aujasite-containing cracking catalyst is characterised ~ by the ~act that catalyst ~rom said inventory is slmultaneously s employed, under condltions different ~rom gas oil cracking conditions, for riser conversion o~ an independently intro-duced ~eed comprising C3 and/or C4 hydrocarbons and that single product stream containing the products o~ both sald riser conversions is taken of~. The independently introduced ~eed may comprise predominantly isobutylene~
and the catalyst prererably comprises rare earth exchanged zeolite Y.
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~7~6ZI~
In a preferred embodiment both conversions are effected in a single riser, wherein the C3 and~or Cl~ hydro-carbon feed contacts freshly regenerated catalyst at the bottom o~ the rlser and the gas oil is fed to the riser downstream. In such embodiment the gas oil advantageously contacts the catalyst at a temperature of 950 to 1100F
; at a catalyst-to-oil ratio in the range of 4 to 10, whilst khe C3 and/or C4 hydrocarbon feed advan~ageously contacts the catalyst at a temperature of about 12504F and a residence kime of 0.1 to 2 seconds - In an alternative embodiment the conversions are e~fected in separate risers which discharge catalyst into a common catalyst settllng zone, optionally through a separator. Both risers may be supplled with ~reshly regenerated catalyst, but alternatively the riser in which gas oil is converted is fed with freshly re~enerated catalyst, that in which C3 and/or C4 hydrocarbon is converted is fed with catalyst withdrawn ~rom said setkling zone. The gas oil is preferably converted at a temperature o~ at lea~ g50F. and a residence time of 2 to 10 ~econds, whllst the C3 and/or C4 feed ls preferably converted ak a tempera~ure of 700 to 1100F, a catalyst-to-feed ratlo o~
~5 to 10 and a residence time of 1 to 10 seconds. In a variation of this embodiment the riser in ~qhich the C3 and~or C4 feed 1~ converted is wholly contalned wlthln a vessel the lower portion of which constitutes said settling zone, which riser is applled wlth catalysk ~rom sald zone.
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1~7~i6Z8 In accordance one preferred embodiment of this inventlon, a C3-C4 rich hydrocarbon mixture or an isobutylene rich stream is contacted with the "Y" faujasite conversion catalyst before contact with gas oil boi].ing range feed material S in an initial portion of the riser or aft;er initial contact with gas oil ~eed. The gas oil conversion is accomplished at a catalyst to hydrocarbon feed ratio in the range of 4 to about 10 and an elevated hydrocarbon ~eed tempera-ture sufficient to ~orm a suspension at a temperature in the range o~ about 950 to about 1100F. Con~ersion of the C3-C4 rich hydrocarbon feed, on the other hand, is accomplished at temperatures above that relied upon for gas oil cracking or lmder lower temperature gas oll conversion temperatures. Thus the C3-C~ hydrocarbon ri.ch feed which may be charged to the riser to encounter the regenerated catalyst at its highest temperature received from the regeneration zone may be converted at a temperature o~ -about 1250F before the suspension thereo~ is brought ln contact wlth gas oil feed ln the riser. Therefore, the residence time o~ the C3 C4 hydrocarbon rich ~eed at high temperature conditions be~ore gas oil contact may be up to 1 or 2 seconds or it ma~ be only a ~raction of a ~econd, as llttle a~.one-tenth of a ~econd, but the contact time under lo~er temperature conditions may be equal to or greater than , t.hat employed ~or the gas oil conversion operation. In any z5 e~ent, the convFrzion zone 1s mainta1ned under cond1t1onz , :
.
' ,-' ' ~4-' ~7S6;~8 whiçh can provide a hydrocarbon residence t~me within the range o~ 1 to about 12 seconds before sepa,ration o~ the ~u~penslon. This is BO sinc~ elther one o~ the feed~ may be ~ntroduced to the ri~er conver~ion zone. at ~paced apart intervals lying in a downstream portion thereof. During this combinatlon conver~ion operation9 the "Y~ ~au~a~ite catalyst provides hydrogen trans~er activity and c~cliæation ~lectivity which converts introduced and ~ormed C3-C~ hydro~
carbon~ to aromatics, alkyl aromatics and some low bo1ling gaseous material.
The C3_C~ rich hydrocarbon feed materlal or the isobutylene rlch feed may be separately ~urnace heated or heated by other suitable means to a temperature suitable for introduclng to the riser convers~on zone. The C3-C4 rlch hydrocarbon ~eed ~nitially contacting the freshly regenerated catalyst may encounter signiflcantly di~erent hlgh t~mperature residence times depending upon whether the ga~ oil i~ introduced to an inltlal, intermediate or down-stream portion of the r~ser conversion æone.
Cataly~t particles separated ~rom the conversion ~on~ are Btripped in a ~tripping zone countercurr0nt to rl~ing stripplng ~a~ such a~ ste&m as ment~oned above. The ~tripped catalyst is then transferred to a cataly~t regeneration z~ne not shown for the removal o~ depo~ited carbonaceou~
makerial b~ bu~ning thereby heating the catal~st to an elevated ~ temperature ln tha range of 1150F. up to 1500 or 1600Fo -' . ~"
_5_ ~756Z8 In a ~urther ~avoured embodiment o~ the invention a second separate riser reactor discharging into a catalyst separation zone such as one or more cyclonic separators is provided wherein catalyst particles are separated ~rom hydro-carbon vapors and thereafter stripped in the same or a dif~erent stripping zone than that used ~or strlpping catalyst separated ~rom the gas oil riser conversion operation. In accordance with this embodiment the strlpped catalyst separated from each riser conversion zone may be passed to a common regeneration zone or all or a portion of the catalyst separated ~rom the gas oil riser conversion zone may be cascaded to the second separate riser reactor wherein it is contacted with a gaseous stream rich in C3-C4 hydrocarbons. In this arrangement the catalyst separated from the gas oil conversion step generally at an elevated temperature of at least 900F is available for ~low upwardly through a second separate riser conversion zone cuspended in normally gaseous C4 and lower boiling ~eed material.
~n this invention, a C3-C4 rich h~drocarbon mixture or an iso-butylene rich feed material i~ combined with ~reshly regenerated "Y" fau~asite conversion catalyst or that separated and cascaded ~rom the ~as oil conversion zone under conditio~s to provide a catalyst to h~drocarbon ~eed ratio in the range o~ 5 to about 40 ~ at an ele~ated hydrocarbon ~eed temperature su~icient to ~orm a -~ suspension at a temperature in the range o~ about 900F to about ,25 ~ 1100Fq The normall~ gaseous hydrocarbon-catalyst suspension '~ passes upwardly through the second riser conversion zone under conditlons providing a h~drocarbon residence time within the ~, ; range o~ 1 to about 10 seconds be~ore separation o~ the suspension.
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~117562~
Durlng this operation~ the "Y" ~au~asite catalyst comprising hydrogen trans~er activity and cyclization selectivity convert~
the C3-C4 hydrocarbons -to aromatics, alkyl aromatics and low boiling gaseous material.
Catalyst particles separated from the conversion zones herein de~ined are caused to ~low downwardly to and through one or more stripping zones countercurrent to rising stripping gas such as steam. The stripped catalyst is then tran~ferred as above provided or to a catalyst regeneration zone not shown for the removal of deposited carbonaceous material thereby heating the catalyst to an elevated temperature.
In yet a further advantageous embodiment o~ the invention, a restricted or relatively short riser reactor discharging into the catalyst separation means such as one or more cyclonic separators at the riser outlet is provided within the upper portion of the enlarged vessel so that the restricted rise~ extends upwardly ~rom within the collected bed of catalyst to an upper portion of the vessel. In thiæ
arrangement the catalyst separated from the gas oil conversion step at an elevated temperature is available ~or ~low upwardly through the re~tricted riser conversion zone suspended in normall~ gaseous C3-C4 hydrocarbon feed material. In this inventlon~ a C3-C4 rich hydrocarbon mixture is combined with faujasite conversion catalyst separated from the gas oil conversion zone at an elevated cracking temperature to ~orm a ~uspension o~ catalyst to hydrocarbon feed ratio in the range of 5 to about 40 at an elevated suspension temperature in the range of about 700 to about 1050F~ The C3-C4 rich hydrocarbon ~eed stream may be furnace heated to an elevated temperature 1n the range o~ 550F to about 900F be~ore ~L~75~Z~
entering the restricted riser conversion zone. On the other hand, to vary the catalyst to hydrocarbon ratio within the restricted riser conversion zone, steam may be used along with the C3-C~ hydrocarbon stream. Also steam may be used to e~fect the li~t characteristics o~ the suspension to pass upwardly through the restricted conversion zone. The suspension formed as herein provided passes upwardly through the restricted riser conversion zone under conditions providing a hydrocarbon residence time within the range of 1 to about 10 seconds before discharge and separation o~ the suspension by cyclonic means.
During this operation~ the ~au~asite catalyst providing hydrogen trans~er activity and cyclization selectivity converts the C3-C4 h~drocarbons to aromatics; alkyl aromatics and low boiling gaseous material.
Catalyst particles separated from the conversion zones herein identified are caused to ~low downwardly to and through a stripping zone countercurrent to rising strlpping -~
gas such as steam. The stripped catalyst is then transferred to a catalyst regeneration zone not shown ~or the removal of deposited carbonaceous material thereby heating the catalyst to an elevated temperature It is contemplated providing separate stripping - zone~ ~or stripping cat~lyst separated from each rlser con-i .
~ version zone and adding heat to each strlpping operation.
~or ex~mple, either one or both stripping operatlons may be ; pro~ided with hot regenerated catalyst to raise the temperature o~ the stripping zone. On the~other hand~ where a single ; stripping zone is used~ it may also be advlsable to bring ~ ~ stream o~ hot re~enerated catalys~ into the ~tripping operation to maintain lts e~icienc~ at a high value.
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~75~Z~
It is also contemplated passing the relatively cold catalyst o~ the C3-C4 hydrocarbon conversion step to a lower portion of the gas oil separated catalyst stripping step and providing multiple stripping gas inlets to the stripping æone.
. ~ The invention will now be illustrated with re~erence to the accompanying drawings, in whlch:
Figure I is a diagramrnatic sketch in elevation o~ an embodirnent of the invention employing a single riser;
Figure 2 is a diagrar~matic sketch in elevation ) of an embodiment of the invention employing separate risers .~or convers'Lon o~ the two feeds, each supplied with regenerated catalyst;
Figure 3 depicts an embodiment similar to that of Figure 2, dif~ering there~rom in that the arrangement j is modi~ied to cascade catalyst, without regeneration, ~rom the first riser to the second5 and Figure 4 iB a diagrammatic sketch in elevation o~ that embodiment of the invention wherein a second riser : :
is enclosed within a vessel, the lower part of which serves ;) a~ catalyst settling'zone~
Throughout the drawings, like numerals designate like parts. .
D~.SCUSSION OF SPECIFIC EMBODIMENTS
Principal Embodimen~ A.
:
Referring now to Figure I, there is shown a riser conversion zone 2 supplied with hot regenerated catalyst by j conduit 4 provided with a catalyst ~low control valve 6.
Steam i~ 'Lntroduced to a bottom portion o~ riser 2 by one or more steam inlet conduits 8 and/or 10 and a gas oll. ~eed is introduced by inlet condult 12 whlch pro~ects upward:Ly ; lnto the bottom portion of riser 2. A C3-CL~ rich hydrocarbon .~.
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~75~;21!3 ~raction may be introduced separately or wlth steam by conduit 8 to the bottom portion of rlser 2 for adm~xture with hot regenerated catalyst. A suspension of catalyst in up~low gasiform hydrocarbon material with or without steam provides a mix temperature of at lea~t 1100F initially ~ormed and passed upwardly through an annular section o~ riser 2 about a gas oil inlet means 12 under velocity conditions selected to provide a hydrocarbon residence time as low as about one-tenth of a second up to about 1 or 2 seconds. The upflowing initially ~ormed suspension in the annulu~ of rlæer 2 is thereafter combined with preheated hydrocarbon feed such as a gas oil ~eed introduced by conduit 12 pro~ecting upwardly into the bottom of riser 2. The thus formed suspension at an elevated cracking temperature of at least 1000f is caused to ~low upwardly through the remaining portion of the riser under hydrocarbon conversion conditions. On the other hand, the gas oil ~eed may be introduced at spaced intervals along the riser as by condiuts 14 and 16. In yet another embodiment it is contemplated initially li~ting the hot regener~ted catal~st ~20 with steam or other i~ert gas before contact with the gas oil ~eed lntroduced by conduit 12 ~or upward ~low through the riser, Additional gas oll feed may also be added downstream to the thus formed suspension. Thereafter gaseous hydrocarbons rich in C3-and C4 hydrocarbons are introduced to the upflowing suspension by conduit 16 or a ~urther downstream Lnlet conduit not shown permitting a minimum residence time o~ about 1 second ~or low temperature upgrading as herein described. In the arrangement o~ Figure I, the suspeD6ion in riser 2 is clischarged into cyclon$c separatlon zones 18 and 20 hou~ed in the upper , ., : , ,, , --10--7~6~3 portion of vessel 22 wherein separation o~ catalyst .from hydrocarbon vapors is accomplished. Hydrocarbon vapors .separated from catalyst then pass into a plenum chamber 24 ~or removal ~rom the vessel by condult 26. Catalyst separated ~rom hydrocarbon vapors in cyclonic means 18 and 20 pass by diplegæ 28 and 30 to a fluid bed of catalyst 32 maintained in the lower portion of the vessel 22. The fluid bed o~
: catalyst 32 is in open communication with a lower extending stripping zone 34 therebelow to which -the ~luid bed of catalyst moves generally downward countercurrent to rising stripping gas introduced by conduit 36. The stripping zone is maintained at a temperature within the range of 900F to 1150F and the higher temperatures may be ~acilitated by the addition o~ hot regenerated catalyst to the catalyst in the stripping zone by means not shown.
Stripped catalyst i8 removed from a bottom portion o~ the stripping zone by conduit 38 for trans~er to a catalyst regeneration zone not shown~ Stripped catalyst may also be recycled to the riser inlet by conduit means not shown . when it is desired to provide catalyst to hydrocarbon ratios greater than 20 and as high as about 80~
The fluid bed o~ catalyst 32 separated ~rom the riser conversion zone 2 is at an elevated temperature and may be in the range of ~rom about gO0F to about 1100~.
As suggested above, gaseous hydrocarbon feed such as a mixture o~ C3-C4 hydrocarbons may be used to form a high te~perature suspension in a bottom portion o~ riser 2 by use of either ~onduit 12 or 8 alone or in combination with one another before gas oil is lntroduced to a downstream portio~ of riser 2 as by one or both of conduits 14 and 16.
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5i6Z~
Also3 as a means for controlling catalyst to hydrocarbon ratios in the riser an inert gas may be initially employed to form a suspension in a bottom portion of the riser into which C4 and lighter hydrocarbons and gas oil are dispersed as herein provided. The suspension formed will vary consid-erably in temperature as herein provided and in catalyst/
- hydrocarbon ratio but generally will be in the range of 10 to about 40.
The method and ystem of Figure I above described may be modlfied considerably in opera-ting combinations without departing from the concepts of the present invention. In addition to the embodiments above identified~ riser 2 may be substantially e~ternal to vessel ~2 and stripping zone 34 rather than pass upwardly through substantiall~ the center thereof In this arrangement, the riser relied upon to upgrade C4 and lower boiling hydrocarbons and gas oil may be provided with additional hot freshly regenerated catalyst in ~ downstream portion of the gas oil riser con~ersion section.
In one or more of the above defined embodiments, the C~ and lower boiling gaseous feed components contact acti~e conversion catalyst o~ the faujasite type at a temperature within the range o~ 700F up to about 1100F and the gas oil ~eed contactæ
the fau~asite catalyst preferably at temperatures in excess o~
900F and as high as 1100F. In yet a further embodiment it 25 : i5 contemplated employing a riser system in whLch the gas oil feed inltially forms a high temperature catalyst/oll suspenslon in the bottom annular portion of the riser about inlet conduit 12 through which dispersion steam is introduced, additional gas oll feed may be added to the suspension as by condult 14 and a C4 rlch ~tream may then be added to the up~lowing suspension as by conduit 16. In other words, lower boiling gaseous , _. . .. _ _ ._.. . . ._ .. . .. ,.. ., . .. .... . .. . . . . . . . . .. .. , ., . __, .. __, . __ ~7~Z~
hydrocarbons such as a C3-C4 rich stream is brought in con-tact with the gas oil-catalyst suspension in a downstream or upper portion of the riser conversion zone.
Principal Embodiment_B
Referring now to Figure II, there is shown a riser conversion zone 92 supplied wi~h hot regenerated cata-lyst by conduit 94 provided with a catalyst flow control valve 96. Steam is introduced to the bottom of riser 92 by one or more steam inle~ conduits 98 and about a gas oil inlet conduit 100 which projects upwardly into the bottom portion of riser 92. A suspension of hot freshly regenerated catalyst in upflowing gas oil and steam provides a mix temperature of at least 950F. which is passed upwardly through the riser 92 under velocity conditions selected to provide a hydrocarbon residence time within the range of 2 to about 10 seconds.
The upflowing suspension in riser 92 is discharged from the end thereof into a separation zone, shown in the drawing, to house one or more cyclonic separation zones.
On the other hand, riser 92 may discharge dir-ectly into one or more cyclonic separating means, as shownin Figure III discussed below, for separating fluid catalyst particles from hydrocarbon vapors.
In the arrangement of Figure II the suspension in riser 92 is discharged through slotted openings at the riser outlet into an enlarged se~tling zone of reduced fluid stream ve}ocity or vessel 102 wherein separation o catalyst from hydrocarbon vapors is encouraged by a substantial reduction in the suspension velocity. Hydrocarbon vapors then pass through cyclonic separation means 104 for removal of ~;
entrained fines before the hydrocarbon vapors pass into a plenum chambex 106 and removal from the vessel by corlduit 108.
, ~j ' ' ~756~3 Catalyst separated from hydrocarbon vapors by settling and in cyclonic means 104 pass to a fluid bed of catalyst 112maintained in the lower portion of vessel 102. The fluid bed o~ catalyst 112 is in open communication with a stripping zone 114 therebelow through which the fluid bed of catalyst moves countercurrent to rising stripping gas introduced by conduit 116. Stripped catalyst is removed from a bottom portion of the stripping zone by conduit 118 for transfer to a catalyst regeneration zone not shown. The fluid bed of catalyst 112 separated from the riser conversion zone 92 is at an elevated temperature in the range of about 800F. ~o about 1000F.
A second separate riser conversion zone 120 is provided in parallel arrangement with riser 92 which also discharges into an upper portion of vessel 102. Risers 92 and 120 are preferahly positioned within vessel 102 at least at their discharge end so that a suspension of catalyst and hydrocarbon vapors is discharged substantially adjacent the inlet of cyclonic separation means within the vessel. A
gaseous hydrocarbon feed such as a mixture of C3-C4 hydrocarbons or a C4 rich fraction is introduced to the bottom inlet conduit 126 of riser 120 for admixture with hot reg~nerated .
catalyst particles in condu~:t 124 to form a mixture or sus-pension at a temperature within the range o~ 700~F. to about 1100F. The suspension formed in a catalyst/oil ratio in the range of 5 to about 40 is passed upwardly through riser 120 under conditions to provide a hydrocarbon residence time within the range of 1 to about 10 seconds. The upwardly flowing sus-pension in riser 120 is discharged in the speci~ic arrangement oi Figure II from the upper end thereof through slots provided into the enlarged settling section of vessel 102. rrhe discharged suspension is separated by catalyst settling induced by a " ~
37~6'2~ l _____ __ __ _ :
drop ln the suspension velocity and by the aid of cyclonic ~eparat~on means such as cyclonic means lt)4. The separated catalyst i~ returned to the ~luid bed of catalyst 112. The discharge end of riser 120 may also be provided with one or more cyclonic separation mean~ BO that the auspension pa~sed ~pwardl~ through the riser will pass directly into the cyclonic separator~ rather than pass f~rst into the enlarged ~ettllng ~ -zone and then through cyclonic ~eparatlon means.
Principal Embodiment C
In the ar~angement of Figure III a gas oil ~;
conversion riser 40 is charged in a bottom portion thereof with gas oil by conduit 42, steam by conduit 44 and hot freshly regenerated catalyst by conduit 46 to form a sus- . :
pension at an elevated cracking temperature of at least about 1000F. The suspension formed is passed through the rl~er under condition6 to provide a hydrocarbon residence time ;
ln the range of 2 to 10 or more seconds be dlscharged ~rom th~ riser dlrectly into a c~clonic separation zone 48. Cataly~
particles separated from-hydrocarbon vapo~s in zone ~8 are pa~sed by dipleg 50 to a bea o~ cataly~t 52 in a stripping zon~ therebelow, Hydrocarbon vapors separated from cataly~t ~n zone 48 are conveyed to a collecting zone 54 or plenum ch~mber in the upper portion o~ vessel 56 before removal .
therefrom by conduit 58.
.
atalyBt bed 52 is conflned within a stripping -~ection ln the lower portion o~ ve~sel 56 and i~ ad~acent to .. .
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~756Z~
a ~econd bed of catalyst 60 but separated there~rom by ~
~ubstantiall~ vertical baffle 62. Ba~fle 62 is provided in an upper portion thereof with a plurality of catalyst trane~er slots 64 for trans~errin~ catalyst from bed 52 to bed 60 as more ~ully discussed below. The catalyst ln bed 52 at an elevated temperature in the range of about 900F. to about 1000F. m~y be ~urther temperature elevated by adding hot r~generated catalyst directly to the bed. Catalyst bed 52 moves generally downward and countercurrent to rising stripping ga~ introduced by conduit 66. Stripped catalyst at an elev~ted temperature in the range o~ 850F. to about 1000F. i~ removed by conduit 68 and pa~sed to the bottom portion oP a second . riser conversion zone 70. Steam is introduced to a bottom por~ion o~ riser 70 by conduit 72 and normally gaseous hydro-carbons comprising C4 and lighter hydrocarbons are introduced by conduit r4. A suspension o~ catalyst in normally gaseous hgdrocar~ons and steam is ~ormed which then moves upwardly through riser conversion zone 7G at a tem~erat~re ~rithln the range o~ 800FQ to abou~ 1050F. under veioclty conditions pro~iding a hydrocarbon residence time in the range o~ 5 to ; 15 ~econds~ The suspension passin~ithrough rlser 70 ls dischar~ed in this arr~ngement directly into a cyclonic se~aration zone 76 wherein hydrocarbon vapors are separated ~rom catalyst particles. The hydrocarbon vapor~ and steam ~ pa~s overhead to plenum ch~mber 54 for admixture wlth hydro-carbon products o~ ga~ oi~ cracklng, Cataly~t separated ~n ~one 76 ls conveyed by dipleg 78 to fluld catalyst bed 60.
Catalyst bed 60 will normally be at a lower temper~ture than i ~75~
~ed 52 but thls can be remedied to some ~xtent by conveying catalyst particles through slots 64 in baffle 62 from bed 52 to bed 60~ A1BO~ lt is contemplated adding hot freshly regenerated catalyst to bed.60 to ad~ust the te.~peratur~
~; 5 thereo~ to a de~ired elevated temperature of at least 850~F, and prP~erably at least 950F. Catalyst bed 60 moves -generally downward through lts strippin~ section counter-current to stripping gas introduced by conduit 80. Stripped catalyst r~moved-from the bottom of bed 60 is then conveyed ~ ~.
by conduit 82 to a regeneration zone not shown.
Stripped products and strlpping gas ~eparated from the upper surface of beds 52 and 60 pass through cyclonic aeparating means represented by 84. Gasiform materl~
compri~ing stripping gas separated from entrained catalyst !5 fines pa~s from separator 84 to plenum 54. Separated cataly~t f~nes ~re pas~ed by dipleg 86 to bed 60.
It i~ to be understood that cyclonic separating 48, r6 and 84 may each be a plurallty of interconnected ~eparation zones pre~erably arranged ln sequence to provide ~ :
~0 more than one stage of cyclonic separatlon in the recovery ` : .
of cataly t ~ines from vaporouB hydrocarbon materlal a~d - strlpp~ng gas.
In yet ~nother embodlment, it is contemplated modi~ying the arrangement of either FigureII orIII to u8e ~5 low boiling ga~eous hy~drocarbons such as isobutylene or a miæture of C4 and lower boiling hydrocarbons as a fluidizing gaB lnstea~ of steam introduced to the bottom portion of the :-" gas oil riser conversion zone as by conduits 98 (Fig. II) and : 1 44 (Fig. IV~.
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' lL~7~Z~
On the other hand, steam is a desirable fluidizing medium for use in riser conversion zones 120 (Fig. II) and 70 (Fig.
III) since it may be used to alter or adjust the catalyst/
hydrocarbon ratio in these trans~er conversion zones using the C3-C4 hydrocarbon stream as the primary feed.
Principal Embodiment D
Referring now to Figure IV, there is shown a riser conversion zone 202 supplied with hot regenerated catalyst by conduit 204 provided with a catalyst flow control valve 206. Steam is introduced to a bottom portion of riser 202 by one or more steam inlet conduits 208 external to and about a gas oil inlet conduit 210 which projects upwardly into the bottom portion of riser 202. A suspension of cat-alyst in dispersion steam is thus initially formed into which an upflowing gas oil feed is introduced providing a mix or catalyst-oil suspension temperature of at least 950F. Steam may also be combined with the oil charge. The suspension passes upwardly through riser 202 under velocity conditions selected to provide a hydrocarbon residence time therein preferably within the range of 2 to about 10 seconds. The upflowing suspension in riser 202 is discharged from the end thereof as by slotted openings into an enlarged catalyst settling zone promoted by reduced vapor velocity. On the other hand, riser 202 may discharge directly into one or more cyclonic separating means or immediately adjacent the bell mouth opening thereto for separating fluid catalyst parti-cles ~rom hydrocarbon vapors.
The suspension in riser 202 is discharged into an enlarged zone or vessel 212 wherein separation of cata-lyst from hydrocarbon vapors is encouraged by a substantial ~75~
reduction in the suspension velocity. Hydrocarbon vapors then pass through cyclonic separation means 214 for re-moval of entrained fines before the hydrocarbon vapors pass into a plenum chamber 216 and removal from the vessel by conduit 218. Catalyst separated from hydrocarbon vapors by settling and in cyclonic means 214 pass by diplegs 220 to a fluid bed of catalyst 222 therebelow maintained in the lower portion of the vessel 212. The fluid bed of catalyst 222 is in open communication with a lower stripping zone 224 to which theifluid bed of catalyst moves downwardly to and through countercurrent to rising stripping gas intro-~uced by conduit 226. Stxipped catalyst is removed ~rom a bottom portion of the stripping zone by conduit 228 for trans-fer to)a catalyst regeneration zone not shown. A portion of the catalyst withdrawn by conduit 228 may be recycled to the inlet of riser 202 when a higher catalyst to oil ratio is desired. The fluid bed of catalyst 222 separated from the riser conversion zone 202 is normally (in the absence of restricted riser 230) at an elevated temperature and from about 25F. to about 75~. below the temperature employed at the inlet of the riser conversion zone 202.
A second restricted riser conversion zone 230 is provided within vessel 212 and the presence of such a restricted conversion zone will cause a further reduction in the catalyst bed temperature unless augmented as herein provided. Riser 230 extends from beneath the upper interface -I .. ".".. ..
of bed 222 into an upper portion of the vessel so that a suspension of catalyst and hydrocarbon vapors discharged Er~m the upper end of riser 230 will be substantially adjacent the inlet o~ a cyclonic separation means or discharge dir-ectly into cyclonic separating means. Catalyst separated ,i, ,",i ~
~7~6;~1~
as by cyclonic means 214 is then returned to a lower portion of bed 222 than the inlet to riser 230 by a dipleg 220 as shown. A catalyst withdrawal well about the inlet of riser 230 may be provided. A gaseous hydrocarbon feed such as a mixture of C3-C4 hydrocarbons at a suitable elevated tem-perature is introduced by conduit 232 with or without steam introduced by conduit ~34 to the bottom of riser 230 with suspended catalyst particles from fluid bed 222 to form a mixture of suspension at a temperature within the range of 700F. to about 1050F. me suspension formed in a catalyst/oil ratio in the range of 5 to about 40 is passed upwardly through riser 230 under conditions to provide a hydrocarbon residence time within the range of 1 to about 10 seconds. The upwardly flowing suspension on riser 230 is discharged from the upper end thereof adjacent the inlet to cyclonic separation means or directly into cyclonic separating means on the riser outlet and positioned in the upper portion of the enlarged settling vessel 212.
The discharged suspension is separated by catalyst settling in this embodiment due to a drop in vel-ocity and by the aid of cyclonic separation means such as separators 214. The separated catalyst is returned to the fluid bed of catalyst 222 by diplegs provided. The dis-charge end of risers 202 and 230 may be in a "T" connection and provided with one ox more cyclonic separation means on each end thexeof so that the suspension passed upwardly through the risers will pass directly into the cyclonic separators. This method of handling the suspension clischaxged from the risers provides a more positive control on the contact time between hydrocarbon vapors and catalyst parti-cles.
, ~75~z~3 :
The method and system of Figure IV above described may be modified to some considerable extent with-out departing from the concepts of the present invention.
For example, riser 230 may be a separate :riser, the major portion of which lS external to the vesse:L 212 in much the same manner as riser 202 is external to the vessel. In ; this arrangement, the riser relied upon to upgrade C4 and lower boiling hydrocarbons may be provided with hot freshly regenerated catalyst or catalyst separated from the gas oil riser conversion step either before or after stripping thereof. In yet another embodiment, it is contemplated initially contacting freshly regenerated catalyst in the bottom portion of riser 202 with a C3-C4 hydrocarbon rich mixture to form a suspension and thereafter bringing the ~.
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~7~62~3 suspension in contact with gas oil feed material in an upper portion of the riser at one or more spaced lnter~als be~ore discharg~ thereof into ca~alyst-hydrocarbon vapor separating zones. In one or more o~ the above embodiments, the C4 and lower bolling gaseous feed components may contact actlve conversion catalyst o~ the ~au~asite type at a temperature .
within the range of 800F~ up to about 1100F. and the gas oil feed may contact the catalyst preferably at temperature~
ln excess o~ 900F. and as high as 1100F. In yet a further embodiment it is contemplated employin~ a single riser system in which system the gas oil ~eed initially contacts the hot ~re~hly regenerated catalyst and a stream of C4 and lower boiling gaseous hydrocarbons such as a C3-C4 rich ~tre~m i~
'~ then brought in contact with the gas oil catalyst suspen6ioni 15 ~ in a down-stream or upper portion of the riser conver~ion zone. In yet another embodlment it ls rontemplated providing :. ~ an ~nnular conversion zone about an upper extension oi the ~tripping zone arranged so that stripped hydrocarbons will .
bypass the catalyst ln the annular con~ersion zone but all o~ th~ c~t~lyst~ di~charged from the ~iser con~ersion zone will pas~ into the annular conversion zone before entering . the ~tr1pping zone. In ~hi~ arrangement the feed to either : ~ the rl8er or a~nular conver~i~n æone may be either ga~ oil , ~: or a C3-C4 rich hydrocarbon streamO
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SPECIFIC EXAMPLE
A ~eries of conver~ion runs with an isobutylene rich ~eed were made under selqcted temperature and h~d~ocarbon re~idence time conditions whlch simulate the operations contemplated by the present lnvention and variations thereon.
A catalyst compri~ing 15% REY wa~ contacted under the conditions ldentified ~n the table below which produced the results identified. It was observod upon examination.o~ the product that a conslderable amount o~ hydrogen tr~nsfer occurred along w~th the production o~ a signi~icant amount o~ liquld product.
m e liquid product was identi~ied as consistlng chie~ly o~
toluene, xylenes~ trimethylbenzenes and naphthale~es, Runs were made at a temperature o~ 1050F. and 850F. using a wide spread in h~drocarbon re~idence time. The operating condition~
selected thu~ support the variations in operating arr~ngements contemplated by this invention without inter~ering with prior art operating c~ndltions such as those relled upon for : ~ con~arting a gas oil charge under elevated temperature cracklng conditions.
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~7~6Z8 It ~ill be observed from these data, that at the ~horter resldence time used for the riser conver~ion run~, cracking of Lsobutylene to lowe~ molecular welght gases and to coke i8 much reduced, However, at total converslon levels of 82.6, 6708 and 90.9% of tha i~obutylene~ los~es to un-: de~irable products are 12.21~ and the ratios of isobutane to butylene plus propylene ranga from l,15 to 3 0 25, Thus run 195 ef~ected at a high temperature and ~hort re~idence time supports the c~ncept of the pr~ent invention where the hot ~reshly regenerated catalyst~ cont~ct the C3-C4 r~ch feed initially in either a separate riser reactor or in an lnitial portion of a single ri~er reactor ~ollowed by gas oll cracking. On the other hand~ run 196 supports that portion of the concept of thi~ inven-tion wherein a previously used catalyst i~ contacted ln a separate rlser reactor or in a down-stream portion of a single gas oil riser reactor with the C3-C~ rich gaseoue hydrocarbon feed --material. Thus in any o~ these arrangement~ a "Y" fau~a~lte convbrsion catalyst has act1vit~ and selectivity for hydrogen t~Qns~er reaction and ole~in cycliæation reaction leading to the pro~uction o~ ~igni~icant quantitie~ of lsobutane ~nd aromatic~.
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Claims (11)
1. A process for producing gasoline by riser conversion of gas oil under cracking conditions, employing an inventory of fluidized, faujasite-containing cracking catalyst, characterised by the fact that catalyst from said inventory is simultaneously employed, under conditions different from gas oil cracking conditions, for riser conversion of an independently introduced feed comprising C3 or C4 hydrocarbons and that a single product stream containing the products of both said riser conversions is taken off, said conversions being either (a) effected in a single riser wherein the C3 or C4 hydrocarbon feed contacts freshly regenerated catalyst at the bottom of the riser at a temperature of about 1250°F and a residence time of 0.1 to 2 seconds and the gas oil is fed to the riser downstream to contact the catalyst at a temperature of about 950 to 1100°F and a residence time of up to 10 seconds or (b) effected in separate risers which discharge catalyst into a common catalyst settling zone, the C3 or C4 hydrocarbon feed being converted at a temperature of 700 to 1100°F. and a residence time of 1 to 10 seconds and the gas oil being converted at a temperature of at least 950°F. and a residence time of 2 to 10 seconds.
2. A process for converting hydrocarbons with faujasite conversion catalyst which comprises, passing an upflowing suspension of hot regenerated faujasite conversion catalyst in a C3-C4 gaseous hydrocarbon fraction at a temperature of about 1250°F. through a lower annular portion of a riser conversion zone for a residence time in the range of 0.1 to 2 seconds, introducing a higher boiling hydrocarbon fraction of at least gas oil boiling range into said upflowing suspension downstream of said annular zone at one or more spaced apart downstream intervals and converting the introduced higher boiling fraction at a temperature in the range of 950°F. to 1100°F. at a hydrocarbon residence time up to about 10 seconds to a product rich in aromatics.
separating the suspension following traverse of said riser conversion zone into a hydrocarbon phase and a catalyst phase, and sequentially stripping and regenerating said separated catalyst phase.
separating the suspension following traverse of said riser conversion zone into a hydrocarbon phase and a catalyst phase, and sequentially stripping and regenerating said separated catalyst phase.
3. A method according to claim 2 wherein said independently introduced feed comprises isobutylene.
4. A method according to claim 2 wherein the catalyst comprises rare earth exchanged zeolite Y.
5. A process according to claim 2 wherein the gas oil contacts the catalyst at a catalyst-to-oil ratio in the range of 4-10/1.
6. In a process for converting hydrocarbons in the presence of a faujasite catalyst, the improvement which comprises passing a fluid particle size faujasite conversion catalyst at an elevated conversion temperature to the lower portion of each of two separate riser conversion zones, passing a high boiling gas oil hydrocarbon fraction as feed to the lower portion of one of said riser conversion zones under conditions to form a catalyst/oil suspension in the range of 4-10/1 at a temperature of at least 950°F. which is passed through said riser conversion zone, at a hydrocarbon residence time of 2-10 seconds, passing a low boiling hydrocarbon fraction rich in C3 and C4 hydrocarbons to the other of said riser conversion zones under conditions to form a catalyst/hydrocarbon suspension at a temperature in the range of 700°F. to 1100°F. which is then passed through the second riser conversion zone at a hydrocarbon residence time within the range of 1 to 10 seconds, discharging a catalyst/hydrocarbon suspension from each riser conversion zone and separating the suspensions into a relatively dense fluid catalyst phase and a hydrocarbon phase, recovering the hydrocarbon phase separated from each conversion zone as a combined phase of hydrocarbons, and stripping the dense fluid catalyst phase separated from each conversion zone.
7. A process according to claim 6 wherein each riser discharges catalyst into said zone through a separator.
8. A process according to claim 6 wherein both risers are supplied with freshly regenerated catalyst.
9. A process according to claim 6 wherein the risers discharge catalyst into a catalyst settling zone and the riser in which gas oil is converted is fed with freshly regenerated catalyst, While the riser in which C3 or C4 hydrocarbon is converted is fed with catalyst withdrawn from said settling zone.
10. A process according to claim 6 in which the catalyst-to-feed ratio 5-10/1.
11. A process according to claim 9 wherein the riser in which the C3 or C4 feed is converted is wholly contained within a vessel the lower portion of which constitutes said settling zone, which riser is supplied with catalyst from said zone.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA218,364A CA1075628A (en) | 1975-01-21 | 1975-01-21 | Conversion of hydrocarbons with "y" faujasite type catalysts |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA218,364A CA1075628A (en) | 1975-01-21 | 1975-01-21 | Conversion of hydrocarbons with "y" faujasite type catalysts |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1075628A true CA1075628A (en) | 1980-04-15 |
Family
ID=4102112
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA218,364A Expired CA1075628A (en) | 1975-01-21 | 1975-01-21 | Conversion of hydrocarbons with "y" faujasite type catalysts |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1075628A (en) |
-
1975
- 1975-01-21 CA CA218,364A patent/CA1075628A/en not_active Expired
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