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Патент USA US2409354

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c...,l. GIULIANI Erm.
' ì
' 4lined July 24, 1944
' Char/es /í Ange [I
' ~
Patented Oct. 15, 1946
U-'Nili-‘Eo 1s’iîm‘ Es PATENT orties
V- cago, Ill.,v,assignors- to Universal Oil, Products
Company„» Chicago,y Ill., a corporation oi Dela
,f Application July“ 24, 1944,: Wallin-.546364.
, aoiaims.
(o1. 19o-_521
The invention is directed ton-an improyedzproc#
ess-` for the catalytic conversionfot fluid hydro
suits are ordinarily obtained, particularly in the
reforming-or retreating step, with catalystswhich
carbons and is more particularly'concerned with '
are prepared entirely or partially by synthetic
a- two-stage operation in which hydrocarbon oil
methods. ‘ The solid catalyst particles are pref
heavier than gasoline is> -eatalytically cracked to
produce substantialtyields of gasoline and wherein
vlar »sha-pe» (preferably >substantial-ly spherical).
allor a-selected fraction ofthe gasoline thus pro
duced is reformed or retreated
the presence of
erably in the form- oi granulesof regular or irregu
Howeven it isalso Within theVV scope of the inven
cracking catalyst to improve-its quality. Alter
natively„l ther-gasoline r>or _gasoline fractions sub
tionv toY employ morefñnely- divided catalyst par
ticles, thevchoi'ce» of particle: size depending pri
marily upon` the physical _condition Awhich it is
jected to such». reforming~ or» retreatment may be
desired yto'maintain-in the catalyst beds in the \
derivedfrorn an. external source or .may comprise
reaction and regenerating vessels.
The novel features of the invention arepartio
-ularly` advantageous. as. applied to operations of
the type’in which a relatively compact bed of
gasoline or gasoline fractionsproduced
cracking step' of the same‘systern and hydrocar
bons of similar- eharacteristics from; an external
moving granular catalyst Aparticles is» maintained
The process» hereinyproyided :employs separate
in the reaotion'zone. However, We» also contem
plate an ¿operation ot the-,type `in .which ar rela
tively dense and turbulent fluid-like bed of ñnely
line fractions and for-catalytic cracking or the 20 divided catalyst particles is maintained in the re
action zone. The ‘condition of the catalyst bed
heavier charging oil» tov producergasoline. Both
in the regenerating zone: may be similar to that
reaction zones-are operated continuously With‘a
maintainedin the reaction Zones or, when desired,
separate streamaof actiye‘solid- catalyst particles
relatively compact beds maybe maintained in the
continuously'supplied'to eachwand with a sepa
rate strearn1ofeontaminated catalyst; particles 25 reaction zones anda duid-like ‘bed maintained- in
conñnedv reaction zones Vfor the catalytic reform~
ingV or retreatment `of «gasoline or' selected gaso
continuously withdrawn from eac-h` reaction-zonel
The streams. of contaminated catalyst particles
the regenerating zone-»or vice versa.
are» commingled .and supplied to. a. con-fined regen
and the' characteristicsy ofA the oil to be converted,
the impor-tant factors' w-nichinrluence-the con
version reactions: in an operation oi the general
type above outlined are. temperature, pressure,
space Velocity and catalyst-oil ratio. `The term
“space Velocity” as here used refers to the volume
erating zone wherein the-activity -of the catalyst
is. restored to- the-‘desired relatively- v-hipliyalue >by
burning therefrom combusti-ble >Vcontaminants
accumulated thereby in the reaction; and- retreating zones. ’I-‘he resulting> regenerated catalyst is
then returned, in part, to the‘cracking‘reactor
Aside from the'particular catalyst employed
of. Wei-eht> of` hydrocarbons passed through the
and; in part,v to the retreatingY reactor vfor further .
reaction. zone
use in promoting the cracking and the. retreating
onreformingY operation in- these` respective. zones,
orweightfofoatalyst present therein. It is usually
a given time per` unit Volume
expressed on a WeightP hourly basis (i. e.,~pounds
of reactants per hour, per pound of catalyst).
thus completing‘the catalyst circuit through: the
The term “catalyst-oil ratio” as here used refers
The catalyst employed inv the present »process 40 to the quantity- or weight of oil supplied to the
may comprise-any of the- several» `well known sol-id
crackingcatalysts which arealso- suitable for the
reforming or» retreatment of ‘Glenn-containing
reactionv zone per'. unit> quantity or Weight of oil
supplied thereto in a-ygivenntime. It -is «usually
expressed» on 'a Weightrbasis, (i. e., `poundscf
catalyst per poundÍ oLfï` oil) .
gasoliney ori‘gasoline fractions to' improve their
quality with-respect to octane rating.-bromine 45 In an operation. ofthe fluid bed type or ofthe
compact. mov-ing* bed .type the‘quantity of com
number, blending` value, >susceptibilitylto anti
knock agents such as leadtetraethyl‘or some com
bustible contaminants accumulated. by the cata
bination of `these improvements. Such catalysts
lyst in passing through the reaction zoneY varies in
generally comprisea major proportion of silica
direct relationvwithcthe» extent to .Whichathey oil
and a minor proportion of' one vor more-‘metal 50 undergoing treatment is converted. in> this; zone.
oxides suchas aluminay zirconia and :magnesia
There!areseveralmethodsby which such catalysts
In: cracking heavier oil, for the production. of Agaso'l
line, the combustible deposits on the catalyst. will
increase with an increased yield of gasoline. In
'the catalytic reforming or retreatmentoi gasoline
may besynthesized and it is- also within the scope
of theinvention to employ partially synthetic or
natural-catalysts of this general type. ‘Bes-tire» 55 or. gasoline fractions tof improye'their quality, the
quantity 0f combustible contaminants deposited
on the catalyst per unit volume of oil treated is
from the regenerator is supplied to the retreat
ing reactor, preferably at a somewhat lower tem
perature than that at which the regenerated cata
lyst is supplied to the cracking reactor and at
considerably less than that encountered in the
cracking of higher boiling oil to produce a satis
factory yield of gasoline.
'El a rate so regulated that when the relatively clean
The quantity of combustible contaminants de
and relatively cool catalyst from the retreating
posited on the catalyst in the reaction zone and
reactor is commingled with the relatively hot and
burned therefrom in the regenerating zone deter
more highly contaminated catalyst withdrawn
mines the thermal balance or lack of thermal
from the cracking reactor and the commingled
balance between the reaction and regenerating
stream of catalyst is returned to the regenerator,
steps, in the absence of provision for abstracting
it may be regenerated therein and withdrawn
excess heat or supplying additional heat'to the
therefrom at a temperature substantially corre
system. When an inherent thermal balance ex
sponding to that desired for the catalyst enter
ists between the reaction and regenerating steps,
ing the cracking reactor. Thus, the retreating
the heat stored in the catalyst during its regener
or reforming stage of the process through which
ation and supplied therewith to the reaction zone
catalyst is circulated serves as a cooling step
corresponds to the heat required for conducting
from which relatively clean and relatively cool
the endothermic hydrocarbon conversion reaction
catalyst is obtained for reducing the tempera
in the latter zone. This condition usually does
ture and quantity of combustible deposits in the
not prevail. The quantity of combustible con
commingled stream of catalyst entering the re
taminants accumulated by the catalyst in promot
generating zone, as compared with the tempera
ing the cracking of most higher boiling oil to
ture and quantity of combustion Adeposits in the
produce a satisfactorily high yield of gasoline is
stream of catalyst leaving the cracking reactor.
usually more than that which will result in ther
'I'his dilution and cooling is maintained at the
mal balance between the reaction and regenerat
desired value by controlling the rate at which
ing steps. On the other hand, the quantity of
catalyst is passed through the retreating reactor.“
combustible contaminants accumulated by the
To operate the retreating reactor at a lower
catalyst in promoting the reforming or retreat
temperature than the cracking reactor, provi
ment of most gasoline and gasoline fractions is
sion is made for abstracting heat from the cata
less than that required for thermal balance be 3 O lyst being returned from the regenerating step to
tween the reaction and regenerating steps.
the retreating reactor. This may be accomplished
It will be apparent from the above that the
by passing that portion of the catalyst supplied to
two-stage operation herein provided in which re1
the retreating step through a suitable heat ex
atively heavy oil is cracked to produce a satisfac
changer in indirect contact and heat transfer
torily high yield of gasoline in one reaction zone, Io., sil relation with any desired cooling fluid and, in
while gasoline or gasoline fractions are reformed
the preferred embodiment of the invention, the
or retreated in a separate concomitantly operated
temperature of the catalyst entering the retreat
reaction zone, the contaminated catalyst from
ing reactor is kept at a substantially constant
the two reaction zones commingled and regen
value by varying the quantity of cooling fluid
erated in a common regenerating zone and the
passed through this catalyst cooling step in re
regenerated catalyst returned, in part, to each
sponse and in direct relation to minor variations
of the reaction zones, will result in a closer ap
in the temperature of the catalyst leaving the
cooling step and entering the retreating reactor.
This permits variation in the quantity of catalyst
circulated from the regenerator through the re
tracting reactor and back to the regenerator to
compensate for other variations in the operat
ing conditions, such as, for example, in the tem
perature of the catalyst leaving the cracking re
actor, and thus maintain a catalyst temperature
in the regenerator at the desired substantially
constant value.
The accompanying drawing is a diagrammatic
illustration of one speciñcform of apparatus in
which the improved mode of operation provided
by the invention may be successfully conducted
proach to thermal balance between the reaction
and regenerating steps. The cracking step will
give an excess catalyst deposit for thermal bal
ance. The reforming or retreating step will give
a deñciency of catalyst deposit for thermal bal
ance. When the two steps are operated simul
taneously as herein provided, the average cata
lyst deposit will at least approach that required
for thermal balance between the regenerating
step and the two reaction steps.
Of the important operating variables above
mentioned, the temperature and pressure em
ployed in the reaction zone and the space velocity
are relatively critical for producing a given yield
and quality of gasoline from any specific charg
and the operation of the process will now be de
ing stock with a given catalyst. Of course, any
scribed with reference to the drawing.
one of these three factors may be varied within
The apparatus illustrated in the drawing com
reasonable limits since various correlations of the 60 prises a separating vessel and hopper I for re
three will produce satisfactory results. However,
the fourth important factor, namely catalyst oil
ratio, has a greater range of flexibility. This is
employed to advantage in the present process'to
maintain the desired temperature relationship
between the regenerating step and each of the
reaction steps.
In operating the process of the invention, cata
lyst Withdrawn from the regenerating step is
supplied to the cracking reactor at a temperature
and at a rate regulated to supply substantially
all of the endothermic heat of cracking in this
zone without encountering an excessive decrease
in the temperature of the catalyst as it passes
Additional catalyst Withdrawn
generated catalyst, which is supplied thereto as
will be later described. Separate streams of the
regenerated catalyst are supplied from vessel lv
through conduits 2 and 3 into cracking reactor
4 and retreating reactor 5, respectively.
A relatively compact bed 6 of the catalyst par
ticles is maintained in cracking reactor 4 and a
similar relatively compact bed 1 of the catalyst
particles is maintained in the retreating reactor
4, in the case illustrated.
Catalyst which has promoted the cracking re
action in reactor 4 and become contaminatedwith combustible deposits is directed from'the'
lower- portion of this reactor through conduit 8
into stripping vessel lo. Catalyst which has »been ,
employed to promote the retreating or reforming
gaseous products are ‘_dischargedifrom .thefupper
portion; ol? bed' 'Pinto the spaceprovided- there
reaction in reactor V5l and which cooler and less
highly Vcoritanfiinated " with combustible deposits
above in reactor E. They are thence directed
than they catalyst withdrawn from reactor: 4` is
through line-.30 and valve 3| to suitable. fractione
vating andrecovery equipment` preferably> sepa
.directed through conduit, 9 into the `Vstripping
vessel Iìû. In stripper l!! another relatively com
rate from that tor which vaporous products from
the cracking reactor 4 are supplied, particularly
pac-t bed l I of catalyst particles` is` maintained
and passing through this zone is; substantially
`case the gasoline for ‘ret-reatment.' is derived
.ÍlîOm the. cra/.ching step.
stripped of; occluded and adsorbed volatilehydro
The; streams of catalyst. particles passing from
carbons, as will be later described,
.Substantially Stripped catalyst is directed Írom
reactors 4 and 5 to stripper lil will carry occluded
the lower portion of stripper Ill throughconduit
and adsorbed volatile hydrocarbons which, if left
in. the catalyst stream supplied to the regenerae
l2 into resenerator i3, ywherein another “ rela»
tively oompact‘bed I4 Oi‘ ther catalyst particles ,is
tori-.would be. destroyed' by burning in this,v zone
would `.materially increase the heat
maintained, The catalyst _isregeneratedL as will 1,5 and,
be later described, to restore its activity;liyglourigl-`
ing ‘combustible ,deposits therefrom. as it passes
through @generator I3'. A.. substantial portion
otthe heat of reeeneration> isstored in .the cata.
`Iyst particles as they pass through the regener
ator and resulting hot regenerated catalystis .die
rected from the lower portion or the regenerating
vessel through conduit I5 into a gas-lift transfer
line` I,8 wherein it is commingled with an incom
ing stream of'. transporting gas suppliedA through
line [6 and- valve VI. The. transporting fluid ex
erts `a gas-lift action. on the catalyst particles
with which itis; commingledintransferline; [18
eyolucd‘ inthelregcneratihg step. To recover
these valuable light hydrocarbons they are sube4
sta-Iltially- stripped’from the catalyst before‘it
cntersthc regenerator. To accomplish this, suit
able stripping gas, such
steam, for example, is
supplied to the` lower 'portion of the stripper
through line. 32, valve 33 and a suitable distrîbut-`
ing member 3ft”. and: is directed upwardlyI through
bed I I` ‘in the. stripper counter-current to the gen
eral downward movement of catalyst particles
through the*- bed. ‘Stripping gas and resulting
stripped-out volatile hydrocarbons are discharged
from the upper portion of bed II into the space
and eñîects theirtreturn throughV the gasflift
maintained‘thereabove within the stripping ves
transfer `line tot the separating vesseland catalyst 30 sel. Theyare thence vdirected' through linc- 35v
hopper I.
and valve 35i, preferably to suitable separating
In vessel I the Velocity of the commingled
and .recoveryA equipment,V not illustrated, ‘but
stream of transporting fluid and catalyst. parti'
which may, for example, be the samev fractionat
i‘ng and recovery equipment to which vaporous
clesy is materially reduced-ll to effecty thel substan
tial separation by gravitationV oftheÍ catalyst par- :ie. fr, products from the cracking reactor or vaporous
products from the retreating reactor are sup
the upper portion of vessel I through line I9 and
valve 2‘0: andthe separated catalyst particles col
In passingrv downwardly through the bed I_4 in
lect within the hopper-like lower portion of Ves
the regenerator the catalyst particles are regen
sel I in the` form- of a relatively'compact bed 2l
crated and heated by burning therefrom combus
tlble depositsv accumulatedin the cracking and
from which they are returned, in part, through
the cracking react-or and, in part, through the
retreating reactors'. This is accomplished by
directing oxidizing gas, such as air, for example,4
retreating reattor,-` as previously described', tothe
through líneï 3l, valve 38 and a suitable distribu_t_-_
ing member 39 upwardly into bed I4 in the re
.Hydrocarbon oil. heavier'I thank gasoline> to be
gsrrerator countercurrent to the downwardly
catalytioallyA cracked is: supplied preferablyl in
moving catalyst particles within the bed. Re
preheated essentially vaporous state to the crack;-A
sulting gaseous-products of combustion are dis
ing -reactor ¿l` throughline 2‘2, valve 23 .and a
ticles. `'The transporting gas is discharged from
Suitable distributing member ` 24 disposed in. the. _' charged from the upper portion of bed i4 into
lower‘portion of the reactor; The; hydrocarbon UI) they space provided thereabove within the regen
ei'ator. 'lï‘heyv are thence discharged through> line
vaporsyp-ass upwardly trom -distributingrrnember
24 intoA the. relatively compact catelystbed @and
4c and valvefdl‘h'preferably tosuitable heat re
covery equipment, not illustrated, such as, for
are cracked to the_„desired deg-ree; in passing 11p-'
example', `a-wast`e-`-l-1eat boiler, steam superh-eater,l
wardlythrough the bod under thefcoutrolîled: con
ditions of temperature, pressurefand; spa,marvelou-A Ul ln hot> gas turbine or the like for utilization oft-he
ity» maintained in` this zone. `Vapcrous.` and gas
cousV conversion products are discharged from' the
upper extremityY of bed `(i into the space‘proví'd'ed
thereabove within reactor 4 and are thence cli»
rected through line- 25 and' valvel26, preferably to,~
suitable` fraction-ating and recovery equipment
which ‘does not constitute `a novel portret the; in-.-
readily available heat energy in these gases.
In passing from the regenerator through con
ventionand' is not illustrated..
case illustrated, the opening through thísyalve
Gasoline, or, gasoline fractions`f to be retreated,
and; which may be; derivedrfrom an externa-1
source or may comprise gasoline or gasoline' frac;
tions produced in the. crack-ing step ofithe- proc
ess and separated from the: other cracked prod
duit |15- into the gas-lift transfer line i8, the
overeallt rate of catalyst circulation through the
system is controlled by the adjustment of valve
‘2 which is disposed ih_condu'it I5' adjacent the
discharge‘end» ot the latter. Preferably, -as in the
is-Varied in direct relation iso/changes in the- rate
at which catalyst is passed through the retreat
ing reactor in order that the rate of catalyst» cir’-v
culation through the cracking reactor may beñxed
at the desired value bythe adjustment of valve lë3_
uczts, isi supplied'. preferably in preheated essen
in conduit ila-nd the over-all rate of catalyst cireV
tiallyzvaporous state> through line 21, valve.V 23
anda; suitable distributing member 29 into bed T
inthe. retreating reactor 5. In passing' upward--Y
lythrough bed 1, the gasoline fractions'are re-`>
culation through» the system >adjusted to> accom-'Vn
modate the increase or decrease in its rate` of pas»
sage- through the `retreating reactor.
complete the control', the rate of catalyst circu
lation through the retreating reactor is varied by
formed or retreated to elîect a material- improve-f
ment in their' qualityI andï resulting `vaporousA and 75 the-ladiustment of valveïêâ. in conduit 9' inL re
sponse and in direct relation to minor changes
pulses through line 56 to controller 51. This con'
in the temperature of the catalyst within or en
tering the regenerator, so as to keep the regenera
troller is also the air-operated type, in the case
illustrated, receiving input air at substantially
tor temperature substantially constant, and the
rate at which cooling fluid is circulated through
the catalyst cooler 45, which is provided in con
constant pressure through line 58 and transmit
ting air pressure through line 59 to the dia
phragm of the automatic control valve 54 at a
duit 3, is varied in response and in direct relation
magnitude which varies in response and in direct
to minor variations in the temperature of the
relation to minor variations in the temperature
catalyst within or entering the retreating reactor
prevailing at the thermocouple 55. Thus, when
so as to keep the temperature in this zone sub 10 the temperature in the retreating reactor in
stantially constant.
creases, controller 51 functions to increase the
Provision is made in the case illustrated for
opening through valve 54 and permit the passage
correlating the adjustment of valves 42 and 44 in
of cooling fluid through cooler 45 at an increased
the respective conduits I5 and 9 by automatically
rate, thus bringing the temperature of the cata
operating both of these valves through a suitable ` lyst entering the retreating reactor back to the
controller 45 receiving impulses from a thermo
desired lower value. Conversely, when the tem
couple or other suitable temperature-sensitive de->
perature in the retreating step decreases, con
vice 41 which, in the case illustrated, is disposed
troller 51 functions to restrict the opening
within bed I4 in the regenerator and preferably
through valve 54, thus reducing the rate at which
adjacent the upper end of the bed. Alternatively,
cooling ñuid is passed through cooler 45 and
when desired, this thermocouple 41 may be dis
bringing the temperature of the catalyst entering
posed in conduit I2 or in the intermediate or
the retreating reactor back to the desired higher
lower portion of the catalyst bed in the regenera
tor, Any suitable form of controller capable of
It will be apparent from the above that, with
effecting the adjustment of valves 42 and 44 in
the system of control provided in conjunction
response and in direct relation to minor changes
with the two-stage operation of the process, sub
in the temperature of the catalyst at the point
stantial thermal balance within the system is ob
of measurement may loe employed. In the case
tained and maintained by controlling the rate
illustrated the controller is of the air-operated
at which catalyst is passed through the retreat
type receiving input air at substantially constant 30 ing step, controlling the over-all rate of catalyst
pressure through line 12 and receiving impulses
circulated through the system to accommodate
for varying the air pressure in the outlet line 48,
variations in the rate at which it is passed
from the thermocouple 41 through line 49. Lines
through the retreating step and operating the
50 and 5I, each communicating at one end with
retreating step at a somewhat lower temperature
the air output line 48 from the controller, com
than that prevailing in the cracking step.
municate at their opposite ends with the dia
Aerating lines 60, 62, 64, 66, 68 and 1D, con
phragms of the respective automatic control
taining the respective valves 6 I, 63, 65, 61, 69 and
valves 42 and 44. When the temperature of the
1I and communicating with the respective con
catalyst as determined by thermocouple 41 in
duits 2, 3, 8, 9, I2 and I5 are provided in the case
creases, the controller functions to increase the 40 illustrated for the introduction of suitable aerat
opening through valve 44 and t0 correspondingly
ing gas such as steam, for example, into the col
increase the opening through valve 42, thus in
umns of catalyst particles passing through the
creasing the rate of catalyst circulation through
respective lines at a rate regulated to prevent
the' retreating reactor and increasing the over
excessive compaction of the columns and insure
all rate of catalyst circulation through the sys- l
movement of the catalyst through these conduits.
tem by a corresponding amount. Thus, more of
The aerating gas passes largely in an upward di
the relatively cool and less highly contaminated
rection through the catalyst columns to which it
catalyst from the retreating reactor enters the
is introduced and creates a gas pressure within
regenerator to reduce the temperature of the lat
the respective conduits which is somewhat less
ter to the desired value- When the temperature . than the pressure exerted by the catalyst column
in the regenerator recedes, controller 45 func
at the lower or catalyst discharge end of the re
tions to reduce the openings through the valves
spective conduits but slightly higher than that at
42 and 44 so that a, smaller quantity of catalyst is
passed through the retreating reactor and
their upper or catalyst inlet ends.
The transporting gas supplied to line I8
through the regenerator, thus allowing the tem- f; through lines I6 and I1 may be chosen to suit re~
perature in the latter to increase to the desired
quirements and may comprise, for example,
steam, air, relatively inert gas, such as carbon di
In order that the temperature in the retreating
oxide or combustion gases substantially devoid of
step may be kept substantially constant regard
air, and it is possible to make use of incoming
less of variations in the rate at which catalyst is (it vaporous reactants to be converted in either the
passed through this zone, and in order to permit
cracking or retreating step, outgoing vaporous
operation of the retreating step, when desired, at
a lower temperature than that employed in the
cracking step conducted in reactor 4, suitable
cooling fluid such as steam, water, oil or the like
is supplied to cooler 45 through line 52, passed in
indirect contact and heat exchange relation with
the catalyst about to enter the retreating step
and discharged from the cooler through line 53
at a rate regulated by the adjustment of valve 54 '
in this line. To make this control automatic, a
thermocouple or other suitable temperature
sensitive device 55 is disposed, in the case illus
trated, Within the upper portion of the catalyst
bed 1 in the retreating reactor and transmits im
products from either of these steps, incoming air
for subsequent use as regenerating gas in regen
erator I3 or outgoing combustion gases from the
regenerator as the transporting fluid, in transfer
line I8.
We claim as our invention:
1. The process of catalytically cracking hydro
carbon oil heavier than gasoline and simulta
neously treating gasoline fractions with cracking
catalyst to improve their quality, which comprises
continuously supplying separate streams of active
cracking catalyst particles to separate conñned
reaction zones, contacting the catalyst in one of
said zones with said oil to be cracked and therein
effecting the cracking reaction, contacting the
catalyst in. the other of said zones with said gaso
line fractions and therein effecting their conver
sion to a product of improved quality at a tem
perature lower than that employed in said crack
ing operation, removing a stream of resultant
ating zone by burning combustible contaminants
therefrom, removing heated regenerated catalyst
from said zone and supplying a portion thereof,
While in heated condition, to a cracking zone, in
troducing the oil heavier than gasoline to the
cracking zone and therein cracking the same in
contact with said portion of the regenerated cata
lyst, supplying another portion of said regener
ated catalyst, to a retreating zone, introducing
mon regenerating zone, therein regenerating the
catalyst by an exothermic reaction, returning re 10 said gasoline fractions to the retreating Zone and
sultant regenerated catalyst, Containing heat
therein contacting the same with said other por
tion of the regenerated catalyst at lower conver
stored therein in the regenerating step, in part to
the cracking reactor at a temperature relatively
sion temperature than that at which the heavier
close to that desired for conducting said cracking
oil is cracked in the cracking zone, removing con
reaction, and in part to the other reactor at a 15 taminated catalyst from the cracking Zone and
lower temperature relatively close to that desired
from the retreating zone and supplying the same
to said regenerating zone, and controlling the
for said treatment of gasoline fractions, and con
trolling the rate at which catalyst is passed
rate of catalyst circulation through the retreat
through the last-named reactor in response and
ing Zone in response and in direct relation to
in direct relation to temperature variations in the 20 minor variations in the temperature of the cata
regenerating step to maintain a substantially
lyst undergoing regeneration to maintain a sub
constant temperature in the regenerating zone,
stantially constant regenerating temperature in
and supplying, in the catalyst entering the crack
the regenerating zone. `
ing reactor, substantially all of the heat of endo»
3. The process as deñned in claim 2 further
thermic reaction required in the latter zone.
y25 characterized in that said gasoline fractions com
' 2. .A process for the simultaneous cracking of
prise cracked products produced from said heav
hydrocarbon oil heavier than gasoline and im
ier oil in the cracking zone.
provement of gasoline fractions in the presence
of cracking catalyst, which c-omprises regenerat
ing contaminated cracking catalyst in a regener 30
contaminated catalyst particles from each of said
reaction zones, supplying both streams to a corn
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