Method and system for effecting catalytic cracking of high boiling hydrocarbons with fluid conversion catalysts

A method and system for cracking hydrocarbons with distinct fluid catalyst particles differing in activity, selectivity and physical characteristics is described wherein a common catalyst regeneration system is employed which will measurably contribute to the heat requirements of the operation as well as the activity/selectivity characteristics of the catalyst employed. Except for size, the catalysts upon make-up may have different or identical catalytic characteristics. However, upon contact with a particular hydrocarbon stream, such as vacuum resid, the selectivity and coke producing characteristics of the catalysts may be altered.

BACKGROUND OF THE INVENTION 
The field of catalytic cracking and particularly fluid catalyst systems has 
been in a constant state of development since conception of fluid systems. 
Thus, as new product demands increased and experience was gained in 
operating and design parameters, so also were new catalyst concepts 
developed which further increased needed refinements in cracking 
technology. With the development of high activity zeolite-type cracking 
catalysts, the petroleum refiners once again found themselves in need of 
developing new operating technology. The present invention is concerned 
with a combination operation relying upon distinct catalyst particles 
differing in particle size, activity, selectivity and coke producing 
characteristics, mutually contributing to the catalytic upgrading of 
separate, relatively high boiling hydrocarbon fractions varying 
considerably in coke producing characteristics and/or catalyst fouling 
characteristics. 
SUMMARY OF THE INVENTION 
This invention relates to a fluid catalyst cracking operation employing 
catalyst particles varying in size, activity, selectivity and coke 
containing characteristics which are jointly heated in a catalyst 
regeneration operation during combustion of carbonaceous deposits under 
conditions to cooperatively influence the operating function of the 
catalyst particles when separated on a basis of particle size, activity 
and selectivity characteristics for effecting the segregated conversion of 
various crude oil fractions varying in Conradson carbon characteristics, 
refractory nature, and/or metals content. 
More particularly the present invention is concerned with a cooperative 
arrangement of catalyst handling equipment which will contribute to 
upgrading hydrocarbon fractions varying substantially in coking 
characteristics with catalyst particles segregated so that contributing 
functions of the combination materialize into a novel combination of 
operating parameters. 
The combination operation of the present invention is designed to 
contribute significantly to refining technology by reducing equipment 
needed heretofore, and in reducing the catalyst inventory as well as the 
costs of such operations. In a particular aspect, the combination 
operation is designed to segregate and process different hydrocarbon feed 
materials with different particle catalytic materials of the same or 
different activity/selectivity characteristics so that one portion of a 
hydrocarbon feed is converted with a catalyst of selected particle size 
and a different particle size catalyst is employed to convert a higher 
boiling portion of the feed particularly contributing high coke 
deposition. The deposition of metal contaminants in the feed will also 
occur. Catalyst particles of different particle size employed as herein 
provided are regenerated in a common catalyst regeneration operation under 
conditions mutually beneficial to each other. That is, catalyst particles 
laden with a higher level of carbonaceous material in admixture with lower 
coke containing particles are heated by a controlled burning of the 
carbonaceous materials in a sequence of catalyst regeneration steps 
wherein catalyst particles of lower levels of carbonaceous deposits act as 
a heat sink during combustion of the higher levels of coke deposits on 
other catalyst particles in the operation. To facilitate the recovery of 
heat available in such an operation, it is contemplated adding an 
oxidizing metal component to the catalyst particles and preferably to the 
catalyst particles of the lower coke producing characteristics when such 
is available and which will promote the conversion of CO to CO.sub.2 
during the burning of carbonaceous materials. In addition, it is 
contemplated treating catalyst particles separated as a function of 
particle size comprising metal contaminants following the removal of 
carbonaceous materials under conditions which will reduce the undesirable 
effects of these metal contaminants during the hydrocarbon conversion 
operation in which they are employed. Thus, the novel combination of the 
present invention intends to take advantage of those developments in the 
prior art which particularly improves the operation herein described. 
The present invention particularly concerns a method and system for 
utilizing two substantially different catalytic materials contributing to 
the functions of the other within the constraints of the combination. In a 
more particular aspect, the present invention is concerned with a 
catalytic conversion method and system comprising at least two separate 
riser hydrocarbon conversion reactors associated with a common catalyst 
regeneration system which is operationally enhanced by a catalyst 
combination comprising large and smaller size catalytic materials working 
substantially independently of one another in separate riser conversion 
zones but jointly contributing to the overall processing combination by 
mutual contact in the common catalyst regeneration system. 
The present invention relates to the catalytic contacting of hydrocarbon 
oils comprising gas oils and higher boiling materials in the presence of 
finely divided fluidizable catalyst particles varying in size, but of the 
same or different activity and selectivity characteristics so that fluid 
catalyst particles of selected size characteristics as well as activity 
and low coke producing characteristics are relied upon to catalytically 
convert a hydrocarbon feed of relatively low coke producing 
characteristics to form desired conversion products in a fluid catalyst 
conversion zone. Size selected particles of catalysts of the same or lower 
activity characteristics are relied upon to convert a feed material of 
higher coking characteristics in a separate conversion zone. Catalyst 
particles separated from hydrocarbon conversion products of each of the 
above conversion operations are passed to a common catalyst regeneration 
zone wherein a burning of carbonaceous deposits is accomplished in the 
presence of both catalysts so that the low coke containing catalyst and 
the higher coke containing catalyst are regenerated under conditions 
contributing to the generation of catalyst particles of desired heat 
carrying characteristics for use in the combination operation. 
The present invention contemplates a regeneration operation wherein smaller 
size catalyst particles are ultimately separated from larger particles of 
catalysts by upflowing gaseous material promoting the separation by 
elutriation. In one embodiment of the combination identified, the smaller 
catalyst particles comprise the high coke accumulation characteristics 
and, therefore, are relied upon to supply a major portion of the absorbed 
catalyst heat by burning during regeneration of the mixture of smaller and 
larger catalyst particles. In the combination operation of this invention, 
it is desirable in a specific embodiment that the smaller catalyst 
particles be relied upon to convert the hydrocarbon feed of the highest 
coke producing characteristics so that any fines generated from the larger 
particles of catalyst will find their way during the elutriating particle 
separation operation in the high coke accumulating and/or metal fouling 
portion or section of the combination operation. 
It is also contemplated using the larger particles as the high coke 
accumulator. That is, it is contemplated operating the process combination 
of this invention by having the smaller size catalyst particles as the 
most active catalytic material for conversion of a low coke producing feed 
and rely upon larger particles of catalyst of selected pore distribution 
and of lower activity characteristics particularly for treating a higher 
coke producing feed comprising metal contaminants in the combination 
operation. 
In either of the catalytic cracking operating arrangements briefly 
discussed, it is further contemplated using gasiform diluent materials 
with the separate hydrocarbon feed materials to particularly promote 
distribution thereof during mixing with catalyst particles to form 
suspensions thereof ultimately passed upwardly through fluid catalyst 
conversion operations such as riser reactor conversion zones. The gasiform 
diluent materials employed may be selected from a relatively large group 
of materials such as steam, C.sub.5 and lower boiling hydrocarbons, lower 
boiling alcohols and other materials which will particularly contribute 
mobile hydrogen under the operation conditions employed or carbon-hydrogen 
fragments which will assist with obtaining the production of lower boiling 
hydrocarbon products. 
In a more particular aspect, the method and system of the present invention 
is designed to improve upon the use of low coke forming catalysts such as 
the recently developed crystalline zeolite cracking catalyst of low coke 
producing characteristics in at least one of the fluid catalyst conversion 
zones permitting a desired hydrocarbon feed residence time in the range of 
1 to 10 seconds under elevated temperature cracking conditions. The 
present invention is concerned with a method of operation which will 
circumvent some of the heat sufficiency problems associated with using 
relatively low coke producing high activity crystalline zeolite cracking 
catalyst to convert hydrocarbon feeds and fractions thereof identified as 
of low coke producing characteristics. Thus, the method and system of the 
present invention relies in a particular embodiment upon the use of dual 
riser fluid catalyst cracking operation separately and selectively 
controlled to effect in the presence of small and larger size fluid 
catalyst particles conversion operations which mutually contribute to the 
operation of one another, particularly nurtured when regenerated together 
in a common catalyst regeneration system. 
The combination operation of the present invention particularly 
contemplates the use of different particle size catalyst compositions of 
the same activity and selectivity characteristics or varying considerably 
in activity and selectivity characteristics. That is, as mentioned above, 
it is contemplated employing a catalyst of relatively low activity to 
accomplish one result and a catalyst of considerably higher activity to 
accomplish another result. It is therefore contemplated employing either 
an amorphous or a crystalline zeolite cracking catalyst of reduced 
activity, particularly for converting a high coke producing feed fraction 
charged to the combination. A high activity low coke producing amorphous 
catalyst, a high activity crystalline zeolite or a combination thereof may 
be the catalyst composition for converting a hydrocarbon feed of the lower 
coke producing characteristics. That is, it is contemplated employing a 
catalytically activated crystalline zeolite identified as X or Y type 
faujasite crystalline zeolites alone or in mixture with another catalytic 
component of relatively high cracking activity. The faujasite cracking 
component may be the smaller or larger particle material as the case 
warrants in order to accomplish the cracking operation desired. Generally, 
the crystalline zeolite cracking component, because of its lower coke 
producing characteristics when compared with an amorphous type cracking 
component, will be of the selected particle size providing high activity 
for converting the low coke producing feed. The crystalline zeolite 
cracking component may be one of several different crystalline zeolites 
known in the art, such as the faujasite type crystalline zeolite mentioned 
above, mordenite type cracking zeolites, or it may be a zeolite from the 
class of crystalline zeolites represented by ZSM-5 type crystalline 
zeolite. ZSM-5 type zeolites having been identified as crystalline 
zeolites having a pore opening of at least 5 Angstroms, a 
silica-to-alumina ratio greater than 12 and a constraint index within the 
range of 1 to 12. The zeolites may be retained as separate particles or in 
a support matrix material. The smaller size catalyst cracking components 
may also be low activity crystalline zeolites; also they may be catalysts 
such as those which have been deactivated after substantial use, they may 
be an amorphous type silica-alumina cracking components, or a mixture of 
the two may be employed to provide a less active catalytic cracking 
component for the combination of this invention. Thus, the catalyst 
particle size, activity and selectivity characteristics will depend on the 
mode of operation selected and the refractory nature of the feeds being 
processed in the separate riser conversion zones. 
Processing concepts of this invention are concerned with adjusting and 
generally optimizing the temperature of the various catalyst hydrocarbon 
suspensions formed and hydrocarbons converted in the separate catalytic 
conversion zones. Thus, although various combinations of hydrocarbon feed 
materials may be employed which are relevant to the concepts of the 
present invention, it is intended that gas oils and higher boiling 
products of crude oil fractionation be used to obtain the different 
hydrocarbon feed components used in the process combination of this 
invention. The combination may be employed for converting high boiling 
materials which one might obtain by vacuum distillation such as a vacuum 
gas oil and a higher boiling vacuum bottoms fraction. Thus, as related to 
the processing concepts of this invention, a residual fraction of 
atmospheric distillation and a vacuum bottoms fraction are identified 
herein as a high coke producing feed and the lower boiling gas oil 
fraction obtained from either atmospheric or vacuum distillation are 
referred to herein as a low coke producing feed. It will be recognized by 
those skilled in the art that this relationship is somewhat hypothetical 
and that other feed combinations may be selected which will fall within 
the general concepts of the present invention. It is particularly 
contemplated when employing products of vacuum distillation and residual 
oils as the hydrocarbon feed fractions, to combine with either one or both 
of the hydrocarbon feeds, a gasiform material which will aid with 
dispersal atomization and/or distribution of the feed in contact with the 
catalyst particles and this will help to suppress adverse catalyst/oil 
agglomerating effects obtained in the absence of such gaseous materials 
which will lead to undesired additive coke depositions on the catalyst 
particles. Gaseous materials which may be used for this purpose include 
hydrogen, gaseous hydrocarbon products of cracking, mixtures of low 
boiling paraffins and olefins generally lower boiling than C.sub.5 
hydrocarbons, C.sub.1 -C.sub.3 hydrocarbons and lower boiling alcohols. 
Regeneration of the catalyst particles separated from the respective 
hydrocarbon conversion products of cracking in separate reaction zones is 
accomplished by passing stripped catalyst obtained from each conversion 
operation at an elevated stripping temperature as a mixture of catalyst 
particles into a catalyst regeneration operation, generally identified 
with a system which reduces the overall catalyst inventory of the 
operation, promotes the combustion of carbonaceous deposits and formed 
carbon monoxide to carbon dioxide, and promotes particularly the 
separation of relatively small particles of catalyst from larger particles 
of catalyst. The present invention relies upon the use of particles of 
catalyst of selected size and activity to convert a high coke producing 
feed material and thus to supply a substantial portion if not a major 
portion of the generated heat to the low-coke containing catalyst 
particles. Regenerated catalyst particles recovered at an elevated 
temperature are mixed with spent catalyst particles at a lower temperature 
as charged to the regeneration system to raise the temperature of the 
spent catalyst particles to a more desirable carbon burning regeneration 
temperature. Thus, in one arrangement, the smaller particles in the hot 
regenerated catalyst mixture are separated by gas flow from the larger 
particles and a portion thereof are relied upon through mixing therewith 
to raise the temperature of the contaminated spent catalyst particles to a 
temperature particularly promoting the combustion of carbonaceous material 
on the catalyst by burning in the presence of an oxygen containing gas 
such as air. In some operations, it is desirable to form a catalyst mix 
temperature which is at least 1000.degree. F. upon initial contact with 
regeneration gas. On the other hand, when one desires to particularly 
promote the combustion of carbonaceous material including the conversion 
of formed carbon monoxide to carbon dioxide, it is more preferable to form 
a catalyst mix temperature of at least about 1200.degree. F., thereby 
substantially reducing the burning time to complete the combustion of 
deposited carbonaceous material and formed carbon monoxide. Thus, the 
regeneration system of the present invention relies upon the catalyst 
particles of low coke levels as a heat sink during combustion of 
carbonaceous material on the particles of catalyst of higher coke level 
and provides thereafter for a separate withdrawal of the larger particles 
of catalyst at a desired elevated temperature from the lower portion of a 
dense fluid bed of regenerated catalyst separately from smaller catalyst 
particles in the more dispersed phase of catalyst above the dense fluid 
bed of regenerated catalyst particles. The separation of large and smaller 
particles of catalyst by elutriation is not novel but is believed to be 
novel in the operating arrangement of this invention. 
It is recognized that utilizing catalyst particles of different particle 
size or particle size ranges is only one method for accomplishing the 
results desired within the concepts of the present invention. Besides 
using catalysts of different size and size ranges, one can also enhance 
the separation desired between particles by having catalyst particles of 
different density material or a combination of size and density to achieve 
and maintain the operation desired in the present combination. The 
terminal velocity of round catalyst particles in regeneration gas is 2 ft. 
per sec. for a 250 micron particle and 0.2 ft. per sec. for a 75 micron 
particle. It is clear, however, that the regeneration gas velocity can be 
considerably higher (about 1-10 ft. per sec.) as the concentration of 
particles and other momentum factors are changed and relied upon in the 
operation. The present dual particle size catalyst conversion operation of 
different activity-selectivity characteristics can be successfully 
employed to convert hydrocarbon fractions comprising substantial amounts 
of metal contaminants, thereby depositing or severely poisoning the 
catalyst coming in contact therewith. It is known that catalyst severely 
metal poisoned tend to make relatively large amounts of undesired gaseous 
products. However, the present operation permits one to reduce this gas 
making tendency by contacting such a high metals containing feed under 
relatively low severity conditions. The conversion liquid product of such 
an operation is recovered and all or a portion of this liquid product is 
charged to the conversion zone employing the higher activity low coke 
producing catalyst. Thus, it will be recognized that in such an operation 
the low activity catalyst contact zone is essentially acting as a guard 
chamber removing metals and carbonaceous material from the feed in order 
to prepare a more desirable hydrocarbon feed for contact with the high 
activity low coke producing catalyst in an adjacent conversion zone. In 
this combination, regeneration of the different activity catalyst 
particles in a common regeneration zone provides a most desirable heat 
distribution arrangement for the recovery and distribution of heat between 
the high activity catalyst and the catalyst particles containing high coke 
deposits. Thus, in the combination operation herein discussed, the overall 
catalyst system may be relied upon to protect the catalysts employed from 
unnecessary heat damage by distribution in a system more closely in heat 
balance. One particular advantage of the combination operation of this 
invention is that the very low coke containing catalyst can now be used to 
accomplish particularly desired conversion results in a heat deficient 
operation in combination with a higher coke containing catalyst 
particularly preparing a more desirable feed material for the higher 
activity catalyst operation. In yet another embodiment, it is contemplated 
employing the metals contaminated catalyst to effect relatively high 
conversion of the relatively high boiling hydrocarbon fraction such as a 
residual oil, bearing in mind that gas produced can be used to advantage 
in the refinery operation.

DISCUSSION OF SPECIFIC EMBODIMENTS 
Referring now to FIG. I by way of example, there is diagrammatically shown 
in elevation in combination with one another, a plurality of riser 
hydrocarbon conversion zone operationally attached to a common catalyst 
regeneration system comprising riser and dense fluid catalyst bed 
regeneration operations. In the specific arrangement of FIG. I, a 
hydrocarbon feed or fraction identified as feed #1 and comprising a 
refractory relatively low coke producing feed such as a gas oil or low 
boiling material of crude oil is admitted by conduit 2 to a riser 
conversion zone 4. A gasiform diluent material such as steam, low boiling 
hydrocarbons and lower alcohols may be admitted by conduit 6 for admixture 
with the feed in conduit 2. In this arrangement, a suitable particle size, 
high activity, low coke producing catalyst identified as catalyst "A" is 
admitted to the lower portion of riser 4 by conduit 8 provided with a flow 
control valve 10. A suspension of catalyst particles in hydrocarbon feed 
and gasiform diluent material when employed is formed in the lower portion 
of riser 4 for flow upwardly there-through under catalytic cracking 
temperature conditions in the range of 900.degree. F. to about 
1100.degree. F. depending on the feed charged to the riser. When the feed 
material is a relatively refractory hydrocarbon feed material, then the 
operating temperature conditions will more normally be at least about 
1000.degree. F. Also the hydrocarbon residence time in the riser will vary 
with the feed, reaction temperature conditions employed and product 
desired. With the more refractory feed materials converted to particularly 
gasoline boiling hydrocarbons, the hydrocarbon residence time will be less 
than about 10 and more usually in the range of about 4 to 8 seconds. In 
this specific riser cracking operation, catalyst "A" is chosen to comprise 
the larger sized catalyst particles of high activity and relatively low 
coke accumulating characteristics. 
The suspension passed through riser 4 under hydrocarbon conversion 
conditions is discharged through radiating arm means 12. These radiating 
arm means may be replaced by cyclone separators. The arm means are 
provided with opening means in the bottom surface thereof for discharging 
the suspension generally downwardly and into baffle restricted passageways 
14 formed by baffle means 16 attached to the wall of vessel 18. 
Hydrocarbon vapors separated from catalyst discharged from the riser along 
with stripped products of reaction and stripping gas pass through one or 
more cyclone separators represented by separator 20 for the recovery of 
catalyst fines before withdrawal by conduit 22. 
The separated catalyst collected in downcomer section 14 passes downwardly 
into a lower portion of vessel 18 wherein it is counter-currently 
contacted with stripping gas which is normally steam. The stripping gas is 
introduced to the lower portion of the stripping zone identified as 
section 24 by conduit 26. The stripping section is provided with a 
plurality of downwardly sloping, alternately staggered and spaced apart 
annular baffle members providing a staggered flow path for counter-current 
contact of the catalyst with stripping gas. Stripped catalyst comprising 
relatively small amounts of carbonaceous deposits because of the low coke 
producing characteristics of the catalyst and feed converted is withdrawn 
from the stripping section 24 at an elevated temperature below 
1000.degree. F. by conduit 28 containing flow control valve 23 for passage 
to catalyst regeneration. Regenerated catalyst particles comprising 
catalyst "B" chosen in this arrangement to comprise the smaller catalyst 
particles at a temperature within the range of about 1250.degree. F. to 
about 1400.degree. F. and obtained as hereinafter defined are passed by 
conduit 30 provided with flow control valve 32 for admixture with the 
catalyst in conduit 28 being passed to the catalyst regeneration 
operation. 
In the specific arrangement of FIG. I, feed #2 is higher boiling than feed 
#1 and also contributes substantial coke during the cracking operation. 
Feed #2 is introduced by conduit 34 to the bottom or lower portion of a 
second riser cracking zone 36. Gasiform diluent material, the same or 
different than that used with feed #1, may be mixed with feed #2 by 
conduit 38. Feed #2 with or without gasiform diluent material is admixed 
in the lower portion of riser 36 with hot regenerated catalyst particles 
comprising catalyst "B" passed through conduit 90 containing valve 42 
before discharge into the lower portion of the riser. The high boiling 
feed, gasiform diluent and catalyst are mixed to form a suspension at an 
elevated cracking temperature of at least about 800.degree. F. thereafter 
passed upwardly through riser conversion zone 36. In this second stage 
cracking operation, the conditions may be varied considerably depending on 
the results desired. Thus, if feed #2 is obtained directly from a crude 
oil high in Conradson carbon, metal contaminants or both of these 
materials, the cracking operation in riser 36 may be restricted to a guard 
chamber operation which reduces a substantial portion of these undesirable 
materials from the feed by deposition of undesired materials in the feed 
on the "B" catalytic material or a more severe conversion operation may be 
selected. Mild conversion conditions will provide a product after 
separation of catalyst therefrom which can be more suitably converted to 
desired product with a higher activity catalyst. On the other hand, high 
boiling feed materials of moderate levels of contaminants may be converted 
to desired products other than gasoline by a temperature selected 
conversion operation particularly promoted by the catalyst of high or 
lower activity characteristics. The feed may be converted to mainly 
gasoline using a contaminated but high activity catalyst. In riser 
conversion zone 36, the feed #2 is converted at a temperature less than 
about 1100.degree. F. during a hydrocarbon residence time generally of the 
same or longer or shorter duration than employed in riser 4 processing 
feed #1. On the other hand, at the lower temperature conversion conditions 
below about 950.degree. F., a more dense upflowing catalyst phase may be 
employed, the hydrocarbon residence time in riser 36 may be longer than 
that employed in riser 4 and thus a longer contact time in excess of about 
10 seconds may be employed. With a metals contaminated catalyst, the 
conversion conditions may be selected to produce gasoline or be effected 
under more moderate conversion conditions. 
The suspension in riser 36 is separated from catalyst material in a manner 
similar to that discussed with respect to riser 4. Thus, the suspension in 
riser 36 is discharged through radiating arms 40 and generally downward so 
that the catalyst is collected in downcomer passageways 42 formed by 
baffles 44. Vaporous conversion products, diluent and stripping gas 
separated from the particles of catalyst pass through one or more 
separators represented by separators 46 for the recovery of entrained 
catalyst fines from product vapors. Separated product vapors are withdrawn 
by conduits 48. 
The catalyst particles separated from hydrocarbon product vapors passes 
downwardly through the downcomer zone into the lower portion of vessel 50 
comprising a catalyst stripping section 52. The collected catalyst moves 
generally downward through the stripping section and counter-current to 
stripping gas introduced by conduit 54. The stripped catalyst "B" is 
withdrawn from the lower portion of the stripping zone by conduit 56 
containing a flow control valve 58. 
It is clear from the above discussion that the feed materials charged as 
feed #1 and feed #2 may be selected from a wide variety of composition for 
upgrading within the operating concepts of this invention. For example, in 
a specific embodiment, feed #1 may be an atmospheric gas oil of crude 
distillation having an end point boiling within the range of 800.degree. 
F. to about 950.degree. F. depending upon the source of the crude oil with 
feed #2 comprising the remaining residual portion of the crude oil boiling 
above the separated gas oil fraction. It is, therefore, contemplated, 
depending on the coking characteristics and metal contaminants of the 
feed, to eliminate the vacuum distillation operation which has been 
heretofore a part of most refinery operations. 
On the other hand, it is contemplated using the processing arrangement of 
the present invention to particularly process a vacuum gas oil as feed #1 
and a vacuum bottoms fraction as feed #2. Other variations on feed 
compositions processed may be selected without departing from the scope 
and essence of the present operating concepts. 
Regeneration of the high activity and lower activity catalyst particles in 
a common catalyst regeneration operation may be practiced as particularly 
discussed below with respect to FIGS. I and II. In the arrangement of FIG. 
I, the catalyst particles contaminated with carbonaceous deposits and 
recovered from the above discussed cracking operation are preferably mixed 
with a portion of the hot regenerated catalyst particles obtained as 
hereinafter provided to raise the temperature of the catalyst mixture to 
at least about 1000.degree. F. upon contact with an oxygen containing 
regeneration gas. Normally the regeneration gas will be preheated to an 
elevated temperature of at least about 600.degree. F. before being passed 
in contact with the catalyst mixture. In the arrangement of FIG. I, the 
catalyst mixture is passed to the lower portion of an upflowing catalyst 
particle regeneration zone herein referred to as a riser regeneration zone 
60. The upflowing suspension of catalyst in regeneration gas may be as an 
upflowing relatively dense mass of catalyst particles in regeneration gas 
or a more dispersed catalyst phase upflowing suspension may be relied upon 
for the initial regeneration step. That is, the concentration of catalyst 
particles in upflowing regeneration gas may be within the range of 10 to 
30 pounds per cubic feet. The suspended catalyst particles in riser 60 
admixed with regeneration gas admitted by conduit 62 at an elevated 
temperature of at least 1000.degree. F. initiates burning of the 
carbonaceous deposits on the catalyst particles before discharge from the 
upper end of capped riser 60 through a plurality of elongated slot 
openings 64 in the upper periphery of riser 60. The top of riser 60 is 
capped in the specific arrangement of the figure so that the slot opening 
operates to direct the discharged suspension generally radially outward 
therefrom and preferably into a dense fluid bed phase of catalyst 
particles 66 housed in the lower portion of a regeneration section 
identified with wall section 68. The discharge end of riser 66 may be in 
the interface between the dense and dispersed phase of catalyst, below or 
above a mid section of the dense fluid catalyst bed 66. In the specific 
arrangement of FIG. I, the discharge of riser 66 is about the dense fluid 
bed interface of catalyst bed 66 and generally below the more dispersed 
phase of catalyst particles passing upwardly through a more restricted 
cross-sectional portion of the regeneration vessel identified with wall 
section 70. 
In the regeneration system and method of operation of FIG. I, the mixture 
of large and smaller particles of catalyst discharged from riser 60 into 
bed 66 are caused to be separated by the flow of regeneration gas employed 
so that the smaller particles of catalyst pass overhead into a more 
dispersed phase of catalyst which is caused to pass upwardly through the 
restricted section 70 for discharge by radiating arms 72. The larger 
particles of catalyst discharged from riser 66 are separated from the 
smaller catalyst particles and move generally downward and counter-current 
to regeneration gas introduced to the annular bed by regeneration gas or 
air inlets 74 and 76. Combustion of carbonaceous material is completed 
essentially in the annular fluid bed of the larger particles of catalyst 
before withdrawal by conduit 8 for use as above provided. In this 
regeneration arrangement, the larger particles of catalyst act as a heat 
sink during combustion of carbonaceous material and thus may be heated to 
an elevated temperature within the range of about 1300.degree. F. up to 
about 1400.degree. F. or in some cases as high as about 1600.degree. F. 
In the upper portion of dense fluid catalyst bed 66, the mixture of large 
and smaller particles of catalyst are subjected to elevated temperature 
coke burning conditions during the transition and/or separation of large 
and smaller particle material by elutriation to form a dispersed catalyst 
phase above a more dense fluid bed phase of catalyst particles. Thus, by 
carefully selecting the regeneration gas velocity employed in riser 60 and 
that introduced by conduits 74 and 76, the smaller particles of catalyst 
may be carried overhead through riser section 70 to discharge arms 72. 
Riser section 70 with discharge arms 72 are confined within a portion of 
the regeneration vessel system identified by wall 78. Vessel section 78 is 
relied upon to collect the smaller particle catalyst phase of the 
operation as a relatively dense fluid bed of catalyst particles 80. 
Additional regeneration gas or air may be introduced to a lower portion of 
bed 80 by conduits 82 and 84. On the other hand, a stripping or fluidizing 
gaseous material may be added by conduits 82 and 84 in the event that 
further burning of carbonaceous material is not required in bed 80. Under 
some conditions, it may be desirable to heat soak the particles of 
catalyst comprising bed 80 with oxygen rich gas with or without metal 
deactivating additives to reduce undesirable effects of metal contaminants 
such as nickel, vanadium and copper. In any of the above operations, 
stripping of the catalyst may be particularly desired and may be 
accomplished by adding stripping gas by way of conduits 86 and 88. It is 
contemplated, on the other hand, carrying the upper level of collected 
catalyst within the upper enlarged portion of standpipes 30 and 90 above 
stripping gas inlets 86 and 88. By so restricting the upper level of 
collected catalyst to reside in an upper portion of the standpipes 30 and 
90, the catalyst inventory of the regeneration system is substantially 
reduced. Furthermore, the pressure head developed by the catalyst passed 
through each standpipe may be reduced. On the other hand, it may be 
desirable to aerate the catalyst above the flow control valves in each 
catalyst standpipe comprising the combustion system and such aeration gas 
may be added to a standpipe by one or more gas inlets not shown. In this 
arrangement, the smaller particles of catalyst at an elevated temperature 
within the range of about 1300.degree. F. up to about 1400.degree. F. and 
in some cases up to as high as about 1600.degree. F. are withdrawn by 
conduit 30 for admixture with the larger catalyst particles in conduit 26 
to form a suspension with the larger particles at a temperature of at 
least 1000.degree. F. To accomplish this mixing, the lower portion of 
standpipe or conduit 28 may be larger in diameter than an upper portion 
thereof. The smaller particles of regenerated catalyst are withdrawn by 
standpipe conduit 90 containing a flow control valve 42 for passage to a 
bottom portion of riser 36 and use therein as discussed above. 
In vessel section 78 about the upper end of riser 70, catalyst particles 
are separated from regeneration gas by a combination of one or more 
separating arrangements comprising hindered settling, cyclonic separating 
means, radiating arm means and a combination thereof which cause catalyst 
particles to be concentrated as a stream of particles separated 
substantially from regeneration flue gas. Separated catalyst may be passed 
into a baffled downcomer zone similar to that employed in the 
hydrocarbon-catalyst separation arrangement discussed above. Regeneration 
flue gases separated from the smaller particles of catalyst may be passed 
through one or more connected cyclonic separating means 94 and 96 
positioned in the upper portion of the vessel and withdrawal therefrom as 
by conduit means 98. Catalyst diplegs attached to each cyclone separator 
pass separated catalyst fines to the collected catalyst in the lower 
portion of the vessel. 
Referring now to FIG. II by way of example, there is shown a variation on 
the arrangement of FIG. I particularly with respect to the regeneration 
system and its method of operation. That is, in the FIG. II arrangement, 
spent catalyst comprising the large catalyst particles and the smaller 
catalyst particles, one or both streams being mixed with hot regenerated 
catalyst particles are passed to a large bulb portion of a riser 
regeneration operation zone 100 wherein the catalyst mixture at an 
elevated regeneration temperature of at least 1000.degree. F. is initially 
contacted with regeneration gas such as air introduced by conduit 102 to 
an air distributor grid 104 positioned in the lower portion of a dense 
fluid bed of catalyst particles in the bulb portion of the regenerator. 
The mixture of catalyst particles of high and lower coke deposits are 
heated by burning deposited carbonaceous material with oxygen containing 
regeneration gas as the catalyst and regeneration gas pass upwardly 
through the dense fluid catalyst bed into a more dispersed catalyst phase 
there-above. The suspension in the dispersed phase is passed upwardly 
through the upper restricted cross-sectional portion of the first stage 
regeneration operation and is thereafter discharged through radiating arm 
means 106 attached to the upper most end thereof. The dispersed phase 
suspension may be supplemented with oxygen containing regeneration gas by 
means not shown to promote the flow of the suspension as well as the 
combustion of formed CO to CO.sub.2. 
The suspension of large and smaller particles discharged by radiating arms 
106 are caused to separate and segregate into a bed of relatively large 
particles of catalyst 108 in an inner annular zone formed by a cylindrical 
baffle means 110 open at its upper end so that smaller catalyst particles 
may pass overhead and be collected as a separate second annular bed of 
catalyst particles 112 about the first annular catalyst bed. The second 
separate annular collection zone is formed between cylindrical baffle 110 
and the vessel wall 114. Thus, the mixture of catalyst particles initially 
charged to the bulb portion of the riser regenerator are discharged from 
the upper portion of the dispersed catalyst phase into the first annular 
zone and separated by upflowing gaseous material therein to form a 
separate annular bed of large catalyst particle material in a lower 
portion of the first annular zone. In the catalyst regeneration-separation 
sequence above identified, the particles of catalyst are heated by the 
burning of carbonaceous material and formed carbon monoxide. Depending on 
the operating conditions employed, all or a portion of the combustible 
material may be burned in the bulb-riser regenerator arrangement before 
separation into catalyst systems comprising large size particles of high 
activity separate from smaller size particles of lower activity collected 
in the outer most annular zone. On the other hand, catalyst "A" comprising 
the larger particle catalyst collected as bed 108 may be contacted with a 
fluidizing gaseous material introduced to a lower portion of the bed by 
conduits 116 and 118. This gaseous material may be a relatively inert 
fluidizing gas under the conditions employed, an oxygen containing 
regeneration or any other suitable material for the purpose. Catalyst "B" 
comprising the smaller particles of less active catalytic material is 
carried overhead from the first annular zone by the fluidizing gaseous 
material for collection in the second annular zone. The smaller particles 
thus fluidized are separated at least in part by a plurality of cyclone 
separators 120 and 122 particularly associated with and positioned in an 
upper portion of the second annular zone. Some of the smaller particles of 
catalyst settle out without passing through the cyclones. The catalyst 
particles thus separated from fluidizing gas and/or combustion flue gas in 
cyclones 120 and 122 are passed by diplegs provided into the second 
annular fluid bed 112 comprising the smaller particle, catalyst "B". Flue 
gases and/or fluidizing gas of each of these operations are withdrawn from 
the top of the regenerator vessel by conduit 124 in communication with 
cyclone separators 120 and 122. Catalyst bed 112 is maintained in a dense 
fluid condition by charging gaseous material to the lower portion thereof 
by conduits 126 and 128. The fluidizing gas introduced by conduits 126 and 
128 may be oxygen containing regeneration gas in the event that residual 
coke remains on the less active catalyst particles and removal is 
required. On the other hand, because this low activity catalyst will be 
subjected during the hydrocarbon conversion operation to metal 
contaminated material, it may be desirable to heat soak the catalyst at an 
elevated temperature with an oxygen rich gas under elevated temperature 
conditions above 1000.degree. F. to reduce the effect of the metal 
contaminants in the hydrocarbon conversion operation. 
Catalyst "A" collected as bed 108 and comprising the high activity catalyst 
particles is withdrawn by standpipe 130 for discharge into a bottom 
portion of riser reactor 132 under conditions to form a suspension with a 
selected boiling range hydrocarbon feed at an elevated temperature 
suitable for converting the feed. Temperatures suitable for this purpose 
fall within the range of 900.degree. to 1200.degree. F. and more usually 
are within the range of 980.degree. F. to about 1050.degree. F. Preheating 
the feed charged and mixing the feed with diluents as discussed above is 
also contemplated. The suspension passes upwardly through the riser under 
temperature and hydrocarbon residence time conversion conditions desired. 
In the arrangement of FIG. II, a suspension in riser 132 is passed 
directly into cyclonic separating means 134 and 136 attached to the end of 
riser 132. These cyclone separators may be relatively rough separators or 
a combination of sequentially connected cyclone separators. They may be 
replaced by the separating arrangement discussed with respect to FIG. I. 
Additional cyclonic separating means 138 are provided for separating 
catalyst fines from hydrocarbon product vapors before removal by conduit 
140 for passage to fractionating equipment not shown. 
Catalyst particles separated by any one of the means herein discussed are 
collected in the lower portion of vessel 142 for passage downwardly 
through a catalyst stripping section 144. Stripping gas such as steam is 
introduced to the stripper by conduit 146. Stripped catalyst is conveyed 
by standpipe 148 to the bulb portion of the regenerator vessel 100. In 
order to raise the temperature of the stripped catalyst in standpipe 148, 
hot regenerated catalyst "B" particles may be withdrawn by conduit 150 
from bed 112 for admixture with the spent catalyst in standpipe 148. 
Regenerated catalyst "B" is also withdrawn from bed 112 by standpipe 152 
for passage to the bottom portion of riser 154 to which feed #2 is charged 
by conduit 156. Feed #2, normally higher boiling than feed #1 and 
comprising a high carbon producing feed such as residual oil or vacuum 
tower bottoms with or without metal contaminants, may be combined with a 
diluent gasiform material as discussed above to aid with dispersal and 
distribution of the heavy feed in contact with catalyst "B". A suspension 
is thus formed at a temperature of at least 800.degree. F. which is 
thereafter passed upwardly through the riser conversion zone for a desired 
hydrocarbon residence time. Conversion desired and composition of feed #2 
will control the method of operating riser 154 and this may be in 
accordance with that discussed above with respect to FIG. I. The 
suspension formed and passed upwardly through riser 154 as a dense or 
dispersed phase suspension is discharged from the upper portion of the 
riser directly into cylcone separators 158 and 160 attached thereto 
wherein a separation is made to recover catalyst particles from 
hydrocarbon conversion products. Hydrocarbon conversion products are 
recovered by conduit 162 after passing through a suitable arrangement of 
cyclone separators. A common product fractionation system not shown may be 
used to separate the hydrocarbon products recovered from the operation by 
conduits 140 and 162. The separated catalyst particles are recovered as a 
bed of catalyst 164 which moves downwardly through a stripping zone 166 
comprising the lower portion of vessel 168. Stripping gas is passed to a 
lower portion of the stripping zone by conduit 170. The stripped catalyst 
is passed by conduit 172 to the bulb portion of the regenerator after 
admixture with hot, freshly regenerated catalyst particles in standpipe 
174. 
The arrangements of FIGS. I and II permit innovative modification in the 
systems in several different respects without departing materially from 
the processing concepts of this invention and particularly the catalyst 
regeneration systems discussed. Thus, it is contemplated housing the upper 
end of each riser reaction zone in a common catalyst collecting vessel and 
comprising separating means for recovering gasiform material from catalyst 
particles. In yet another arrangement comprising variations on the 
catalyst regeneration system of FIG. I, it is proposed to modify the 
bottom portion of riser 60 to comprise an enlarged bulb portion such as 
identified with FIG. II. It is also contemplated passing the dispersed 
catalyst phase in the upper restricted section 70 of regeneration vessel 
68 through a more restricted transport conduit communicating with cyclonic 
separating means, thereby eliminating the upper vessel means 78. In this 
arrangement, the overall height of the regeneration system may be reduced 
and standpipes extending downwardly from the cyclone arrangement may be 
joined and separated as required to provide the catalyst streams desired 
of, for example, catalyst "B". 
The catalysts employed in the combination operation of this invention are 
not intended to be restricted to large and smaller catalyst particle 
materials of the same composition even though such may occur to some 
extent in the operation. The catalyst may be of dissimilar compositions so 
that the activity-selectivity characteristics of the individual catalysts 
"A" and "B" can be particularly selected to accomplish the conversion 
operation desired. For example, it is contemplated using as the low 
activity catalyst particles, materials which are amorphous as well as 
materials which are crystalline. The lower activity catalyst material may 
be selected from particular crystalline zeolite compositions of 
significantly reduced activity and selectivity characteristics. That is, 
the smaller particle catalytic material may be a relatively spent and 
catalytically deactivated amorphous or crystalline zeolite catalyst or 
mixtures thereof. Mordenite catalyst compositions employed alone or in 
admixture with amorphous material may be employed as the low activity 
composition. The larger catalyst particles are selected from catalyst 
compositions of higher cracking activity and selectivity characteristics 
which are known and referred to as relatively low coke producing 
catalysts. The higher activity catalyst particles are preferably zeolites 
or a mixture of crystalline zeolites which particularly promote the 
cracking or conversion operations desired of the lower boiling feed 
charged to the combination operation. For example, large catalyst 
particles may be a homogenous mixture of a catalytically activated 
faujasite crystalline zeolite in combination with one of a crystalline 
zeolite selected from the class of crystalline zeolites identified as 
erionite, zeolite T, chabazite, Z-5 zeolite, mordenite, ZSM-5, ZSM-11, 
ZSM-12, ZSM-35, ZSM-38 and ZSM-41. Of particular interest for use as the 
highest activity catalyst particles, whether large or small, is the 
catalyst combination comprising high activity faujasite crystalline 
material in admixture with a ZSM-5 type of crystalline zeolite. 
Having thus generally discussed the method and concepts of this invention 
and specifically described examples in support thereof as represented by 
FIGS. I and II, it is to be understood that no undue restrictions are to 
be imposed by reason thereof except as defined by the following claims.