Method and means for preparing and dispersing atomed hydrocarbon with fluid catalyst particles in a reactor zone

The invention described is concerned with atomizing an oil fraction of crude oil to provide a fog of oil droplets in diluent gaseous material which is sprayed into an upwardly flowing annular dense mass of catalyst particles to form a high temperature suspension therewith and conveyed through a riser conversion zone under selected hydrocarbon conversion conditions suitable for cracking the oil droplets to gasoline and light cycle oil boiling range products. The oil feed preparation and distribution arrangement to form a suspension with catalyst particles of desired elevated temperature is employed in combination with a two-stage catalyst regeneration operation designed and operated to achieve catalyst temperatures at least equal to the pseudo-critical temperature of the oil feed and at least above the end boiling point of gas oil boiling range material and resid product of vacuum distillation.

This invention relates to the catalytic conversion of hyrocarbons with 
fluid particles of catalyst by method and means selected to improve the 
operation and yields of desired products. More particularly the present 
invention is concerned with identifying operating parameters with 
implementing means for particularly promoting atomized-vaporized contact 
of a heavy oil feed with dispersed phase particles of catalyst under 
conditions whereby deleterious coking, carbon formation and desired 
product losses are minimized. In yet another aspect this invention is 
concerned with the conversion of high boiling hydrocarbons such as gas 
oils, residual oils, reduced crudes, topped crudes, whole crudes, residual 
oil portions of crude oils comprising metallo-organic compounds, shale 
oils, oil products of tar sands and oil products of coal conversion and 
mixtures thereof. 
The present invention is directed in one particular aspect to an improved 
feed atomizing method and injection means for obtaining intimate atomized 
oil feed contact with finely divided fluid catalyst particles of 
relatively high surface area and catalytic cracking activity contributed 
by one or more crystalline zeolite materials comprising the catalyst 
particles. Crystalline zeolites suitable for the purpose are identified in 
the prior art and include ultra stable and rare earth exchanged 
crystalline zeolites of large and smaller pore volume. In the prior art of 
U.S. Pat. No. 3,547,805 the hydrocarbon oil feed is charged to the system 
by injecting it as an annulus surrounding a stream of water. This system 
is concerned with atomizing the oil feed and mixing it with steam. 
U.S. Pat. No. 3,152,065 discloses feed injector arrangements which include 
an inner pipe for passing steam and an outer pipe forming an annulus for 
passing oil feed which is mixed in a smaller diameter opening in the end 
of the outer pipe displaced apart from the open end of the inner steam 
pipe. The patent also discloses placing curved stator vanes in the annulus 
adjacent the end of the steam pipe. The feed nozzle combination may be 
used in the bottom of a riser or in the wall of the riser above the 
catalyst inlet thereto. 
U.S. Pat. No. 3,654,140 is directed to a novel cat cracking oil feed 
injector design concurrently feeding steam to the injection zone in a 
volumetric ratio of steam to liquid hydrocarbons ranging from about 3 to 
75, thereby imparting to the resulting mixture an exit velocity relative 
to the fluidized catalyst of at least about 100 feet per second whereby 
the oil feed stock is essentially completely atomized at the nozzle exit 
forming droplets less than about 350 microns in diameter. The nozzle exit 
of each of FIGS. 1 and 2 are shown extended a substantial distance into 
the reaction zone where upflowing dispersed phase catalyst can be attrited 
and erode the nozzle end. 
U.S. Pat. No. 3,812,029 contemplates a nozzle arrangement similar to U.S. 
Pat. No. 3,071,540 except that the outer tube is used to inject water at a 
temperature end flow rate lower than that of oil feed in the center tube. 
An article in the Oil and Gas Journal for Mar. 30, 1981 entitled, "Burst 
of Advances Enhance Cat Cracking", by D. F. Tolen, review in considerable 
detail problems facing modern day refiners processing residual oils 
comprising metal contaminants and Conradson carbon producing components 
boiling above vacuum gas oils. The subjects briefly discussed include 
catalysts suitable for resid cracking in the presence of metal 
contaminants; the effect of metal contaminants on product selectivity; the 
addition of steam and/or water with the feed; catalyst regeneration; feed 
quality; combustion promoters used in regeneration of the catalyst to 
obtain desired regeneration temperature profiles and problems associated 
with sulfur and nitrogen oxides. 
This article further identifies the need to obtain good mixing of the feed 
with catalyst in a riser reactor. In this catalytic-hydrocarbon conversion 
environment, good mixing is said to reduce gas make, increase gasoline 
selectivity, and improve catalytic cracking in preference to thermal 
cracking and reduce carbon formation. 
The above identified operating parameters are intended to also accelerate 
the mixture relatively uniformly within the feed vaporization section of a 
riser reactor in a minimum time frame and thus enhance rapid heat transfer 
from hot catalyst particles to charged feed preferably atomized and thus 
prevent localized enhanced catalyst to oil ratios contributing to a dense 
catalyst bed phase. That is, the operating conditions and methods for 
implementing are selected to ensure a relatively dilute phase suspension 
contact between catalyst particles and atomized oil feed for vaporized 
conversion transfer through a riser conversion zone. Such dilute catalyst 
phase operations include catalyst particle concentrations in the range of 
0.5 to 10 pounds per cubic foot and preferably not above about 5 pounds 
per cubic foot. 
SUMMARY OF THE INVENTION 
The present invention is concerned with providing an improved combination 
of operating parameters and means for achieving intimate high temperature 
contact between an atomized-vaporized oil feed diluent mixture with fluid 
particles of active cracking catalyst in a conversion zone under selected 
conditions of temperature, hydrocarbon-catalyst ratio, contact time 
between oil feed and catalyst, catalyst activity and hydrocarbon partial 
pressure selected to obtain desired selective cracking of the oil feed to 
gasoline product. The oil feed processed by the operating parameters and 
means herein identified comprise gas oil boiling range hydrocarbons with 
or without metallo-organic compounds and substantial Conradson carbon 
producing components boiling above about 1025.degree. F. 
In the combination of oil feed atomization, catalytic conversion thereof 
and regeneration of catalyst particles so used as provided by this 
invention, a high boiling oil feed of at least 600.degree. F. initial 
boiling point and of a gravity in the range of from about 5 to about 28 
API gravity is atomized as herein provided and brought in intimate contact 
with an upflowing annular mass of hot catalyst particles in a fluidizing 
medium. A reactor temperature of at least 1000.degree. F. and sufficient 
to obtain substantially instantaneous vaporization of the atomized oil 
feed and catalytic conversion thereof is contemplated in one embodiment 
under substantially plug flow dispersed catalyst phase conversion 
conditions in a down stream portion of a riser conversion zone. Conversion 
of the oil is restricted to a contact time in the riser within the range 
of about 0.5 up to 6 seconds and more usually less than about 3 or 4 
seconds is a particularly preferred embodiment. The operating modes 
contemplated and suspension relationships between oil feed, catalyst 
particles and diluent material are selected to provide a relatively 
dispersed catalyst phase suspension comprising a particle concentration 
within the range of about 0.5 up to about 10 pounds of catalyst particles 
per cubic foot of riser conversion zone following dispersion in atomized 
oil feed. It is known by those skilled in the art that the concentration 
of catalyst particles in an upflowing suspension may be varied 
considerably by the velocity and volume of fluidizing gasiform material in 
the presence thereof in addition to the volume changes obtained by 
hydrocarbon conversion products obtained in the riser. 
The method of operation contemplated by this invention also includes the 
formation of an oil feed-water emulsion comprising up to about 5 weight 
percent of water and preheated up to about 800.degree. F. which is 
atomized as herein described before dispersion into an upflowing stream of 
catalyst particles. It is particularly desirable to avoid thermal cracking 
of the atomized oil feed admixed with diluent material before contact with 
catalyst particles. Therefore, the atomized oil feed is formed preferably 
external to a riser reaction zone and transferred through conduit means 
housed for example in a heat dissipating sleeve as required which is 
purged with gasiform material such as steam, dry gas, CO.sub.2 or other 
suitable gaseous material. 
The unique and special oil feed preparation device of this invention 
comprising an oil atomizing section, an atomized oil transfer section and 
a distribution or dispersion head for the atomized oil feed within a riser 
contact zone may be employed in one of several different arrangements as 
discussed below. That is a barrel or conduit of the nozzle system may 
extend through the bottom of the riser on the riser axis or penetrate the 
riser wall with a straight or curved conduit means with or without a heat 
dissipating sleeve means above identified. The atomized oil droplets 
within the range of about 10 to about 500 microns resembling a mist or fog 
of oil droplets in a diluent medium is discharged by a plurality of 
nozzles in a confined system more fully discussed below at velocities from 
25 feet per second up to and including sonic velocities. The diluent 
medium used to atomize the oil feed and fluidize particles of catalyst as 
herein provided may be relatively inert or one which will enter into the 
cracking reaction to reduce or promote hydrogen production, hydrogen 
transfer reactions, and deactivate to some extent accumulated metals on 
catalyst particles. The catalyst is preferably recovered from catalyst 
regeneration at a temperature usually above about 1400.degree. F. up to as 
high as 1800.degree. F. by the method and means of copending application 
169086 filed July 15, 1980 and incorporated herein by reference thereto. 
Thus, the hydrocarbon conversion temperature employed is selected to form 
an atomized oil feed-diluent-catalyst particle suspension mixture of 
sufficiently high temperature to accomplish vaporization of the oil feed 
and conversion of the feed during traverse of a riser reactor. Separation 
of the suspension at the riser discharge is accomplished at a temperature 
sufficiently elevated to optimize recovery of vaporous hydrocarbon 
products of catalytic conversion. Suspension temperatures at the riser 
discharge within the range of about 900.degree. up to about 1400.degree. 
F. are contemplated, but will depend upon the particular feed processed. 
The method and means for preparing a high boiling oil feed for dispersion 
contact with fluid particles of catalyst according to this invention is 
one designed to particularly atomize an oilwater emulsion into fine oil 
droplets in the range of 10 to 500 microns and preferably sufficiently 
small droplets to form a oil droplet fog or mist of oil droplets in 
diluent material such as steam, normally gaseous hydrocarbons, CO.sub.2 
and combinations thereof. Thus the oil feed or a water emulsion thereof is 
initially formed into relatively small droplets and the droplets thus 
formed are sheared with a relatively high velocity stream of gaseous 
material to form smaller size droplets less than 500 microns to produce a 
fog or mist thereof. The sheared oil droplets in gaseous diluent are then 
conveyed to a dispersion head coaxially positioned within a hydrocarbon 
conversion zone about which an upflowing relatively low velocity mass of 
catalyst particles pass as a relatively dense fluid mass of catalyst 
particles. Thus in a specific arrangement comprising a riser conversion 
zone, a dense fluid bed mass of relatively hot regenerated catalyst 
particles is caused to flow upwardly through a bottom portion of a riser 
conversion zone and about an atomized oil feed distribution chamber 
provided with a plurality of nozzle means in the upper surface thereof for 
dispersing the atomized oil feed in contact with catalyst particles 
passing between the riser wall and the distribution chamber as an annular 
relatively dense fluid upflowing catalyst mass whereby a dispersed phase 
suspension of catalyst particles and atomized-vaporized oil feed with 
diluent material is initiated for continuous upward flow through the upper 
portion of the riser conversion under essentially plug flow dispersed 
phase hydrocarbon conversion conditions. 
When dispersing atomized oil droplets as a fog or mist in contact with hot 
particles of catalyst to form a suspension therewith, the oil droplet does 
not necessarily need to come in direct contact with hot catalyst particles 
to obtain rapid vaporization thereof. In this environment, heat flows 
rapidly by thermal conduction from the hot catalyst particles to the 
atomized oil droplets and rapidly if not instantaneously vaporizes the 
fine liquid droplets to improve cracking contact with particles of 
catalyst. Therefore when converting oil feed comprising high boiling 
vacuum gas oils and higher boiling components of crude oils, it is 
important to form the suspension as herein provided at a temperature equal 
to or above the end boiling point of the oil feed or at least equal to or 
above the pseudo critical temperature of the oil feed in the event its end 
boiling point is not easily obtained. Atomization of the oil feed may be 
accomplished by a number of different means known in the prior art. It is 
important to this invention however that such atomization be accomplished 
external to a hydrocarbon conversion zone in the presence of gasiform 
diluent material to form a fog or mist thereof comprising droplets smaller 
than 500 microns and thereafter conveying the atomized oil-diluent fog 
mixture to a dispersion head in the hydrocarbon conversion zone for 
contact with catalyst particles as herein provided. 
The improved riser reactor-oil feed system of this invention takes full 
advantage of a high activity and selective zeolite containing cracking 
catalyst employed in the system. The system and method used insures that 
the catalyst-oil phase is well dispersed and fluidized during conversion 
or cracking with vaporized oil feed. In addition, the method of operation 
permits obtaining desired controlled short contact time between oil and 
catalyst particles in a plug flow type of operation before effecting 
catalyst-hydrocarbon product separation rapidly at the discharge end of a 
riser cracking zone. 
In one embodiment of this invention, regenerated catalyst enters a bottom 
portion of the riser conversion zone through a downwardly sloping conduit 
provided with a catalyst flow control valve above a bottom portion 
thereof. The catalyst particles thus charged to the riser as a dense mass 
of particles is mixed with fluidizing and/or fluffing gas charged to a 
bottom portion of the riser to promote or provide for a smooth 
non-turbulent change in direction of catalyst flow to an upward relatively 
low velocity dense flow of catalyst particles toward and about a coaxially 
position oil feed distribution and injection bowl or pot in the riser 
resembling a flower pot in cross-section and provided with feed injection 
nozzles eminating from its upper surface. Multiple feed injection nozzles 
positioned in a circular pattern provide a smooth, well distributed 
introduction of the atomized oil feed and diluent material in contact with 
the upflowing catalyst particles to form a suspension therewith thereby 
assuring more optimum dispersion and utilization of catalyst particles 
contributing to more uniform coke deposition. 
The distribution and dispersion of atomized-vaporized oil feed in contact 
with catalyst particles is enhanced considerably by the use of a 
relatively straight and vertical riser reactor in at least a substantial 
portion thereof maintained under process flow conditions to minimize 
slippage between catalyst particles and vaporized hydrocarbons-diluent 
material in suspension contact therewith. The riser length and volume are 
predetermined and set to provide relatively optimum yields of gasoline 
and/or light cycle oil from a given range of oil feed stocks under select 
unit operating conditions. Optimum operating conditions are maintained 
within relatively narrow limits by precise and substantially instantaneous 
riser temperature control. This is achieved by direct regulation of the 
regenerated catalyst flow in the regenerated catalyst standpipe with a 
slide valve positioned in a lower portion of the standpipe and adjacent 
the riser bottom portion and controlled by the riser outlet temperature 
controller. The regenerated catalyst thus charged to the riser is 
maintained in a relatively dense phase upflowing condition by fluidizing 
or fluffing gas charged to the riser bottom portion and beneath the 
catalyst inlet thereto. The oil feed distribution pot is preferably 
positioned at an elevation intermediate the regenerated catalyst standpipe 
flow control valve and the standpipe inlet to the riser reactor. In any 
event it is positioned sufficiently above the regenerated catalyst 
standpipe inlet to be in a region of relatively smooth upward flow of 
catalyst. 
Undesired prolonged dilute phase cracking of the charged oil feed in the 
riser is maintained at a very low order of magnitude by using highly 
efficient cyclones adjacent to the riser outlet. In a specific embodiment 
not shown they are attached to radiating conduit means which may be 
straight or curved to coincide with tangential attachment to a cyclone. 
Other means known in the prior art may also be employed for separating the 
suspension which will accomplish the results desired. A rapid and 
efficient separation between reaction products of hydrocarbon conversion 
and catalyst not only improves desired product yields but also reduces 
catalyst loading entrainment in the main fractionator downstream of the 
riser reactor. 
From the instant of contact between hot catalyst particles and atomized oil 
vapors in the riser as herein provided, all subsequent conversion 
(cracking) interactions are complicated because catalyst activity and 
temperature conditions are constantly changing throughout the length of 
the riser. Concomitantly with the conversion of a reduced crude there is a 
significant molar expansion coupled with acceleration of both vapor and 
catalyst. 
In order to fully utilize the intrinsic catalytic activity of zeolite 
containing catalysts, proper apparatus design is essential to allow 
intimate mixing at the point of initial contact between hot catalyst 
particles and atomized oil feed such as a reduced crude is critical. 
Further, there is desirably provided a uniform distribution of catalyst 
particles and feed under conditions of minimum back mixing (near plug 
flow) during the concurrent flow of catalyst particles and vaporous 
materials through the riser reactor which is substantially vertical in a 
major portion thereof. Injection of vaporized-atomized feed, rapid 
vaporization of atomized feed in the riser, increased atomization and 
dispersion of the feed, use of a plurality of separate and oriented feed 
nozzles means located in a particular equal area circular arrangement, and 
use of dispersion steam or other fluidizing gas to control the catalyst 
flow velocity above the catalyst choke or defluidization point are all 
aids to improve the mixing of oil feed with catalyst and to minimize the 
deleterious effects of a dense back mixing catalyst bed above the oil feed 
injection point. After obtaining initial catalyst/oil contact, relatively 
dispersed catalyst phase fluidization occurs and the rapid molar expansion 
of hydrocarbon conversion or cracking causes a sharp increase in vapor 
velocity, which acceleration of catalyst particles over a few seconds from 
a relatively low initial velocity to one approaching that of the vaporous 
material comprising hydrocarbons and fluidizing gaseous material. Although 
the gas velocity tends to drive individual catalyst particles upward, 
there are the opposing effects of gravity and inertia, with the result 
that the velocity of the solid catalyst particles is less than the gas 
velocity. This difference is known as the "slip velocity". For any section 
of a riser reactor, the slip ratio S can be defined as the ratio of 
catalyst residence time/vapor residence time, i.e.: 
##EQU1## 
where T.sub.c =catalyst residence time 
T.sub.v =vapor residence time 
V.sub.v =vapor velocity 
V.sub.c =catalyst velocity 
It has been observed that after an initial acceleration through 
approximately 10 feet of the riser, catalyst particle velocity differs 
from the vapor velocity by an amount approaching the free fall velocity 
V.sub.f, and the following equation holds: 
##EQU2## 
High vapor velocities not only reduce the catalyst hold up or slip that 
occurs in a riser but also allows considerable improvement in catalyst 
distribution. Radial maldistribution (high localized catalyst 
concentration at the wall, hence high local C/O ratios) and other 
aberrations that cause deviations from ideal plug flow are also minimized 
with high vapor velocities, with catalyst distribution tendering to be 
more uniform with the extent of vertical displacement up the riser.

DISCUSSION OF SPECIFIC EMBODIMENTS 
Referring now to FIG. I by way of example there is shown the bottom or 
lower portion of a riser reactor zone 2 in association with a regenerated 
catalyst standpipe 4 provided with a flow control valve 6. An annular gas 
distributor ring 8 is provided in a bottom portion of riser 2 for 
introducing and distributing fluffing and fluidizing gaseous material such 
as CO.sub.2, steam, normally gaseous hydrocarbon or a mixture of two or 
more of such materials by conduit 10 for maintaining catalyst particles 
charged to the bottom of the riser by standpipe 4 as a generally fluid 
upflowing smooth dense mass of catalyst particles. This fluidizing gas is 
charged at a linear velocity in the range of 0.1 to about 0.5 feet per 
second and thus contributes to achieving smooth turn around of downflowing 
catalyst particles to an upflowing relatively smooth dense fluid mass of 
catalyst particles with the rate of catalyst flow up to the feed pot 
controlled by valve 6 in the catalyst standpipe 4. Thus it is intended to 
maintain a dense fluid mass of upflowing catalyst particles in the bottom 
portion of the riser reactor 2 and about the feed inlet conduit 12 
terminating in an upper distributor pot 14 and forming an annular 
passageway 16 with the wall of the riser reactor zone. The top closed 
surface of pot 14 is provided with a plurality a nozzle means 18 arranged 
in a circular pattern as shown in FIG. III more fully discussed below. 
Conduit 12 is provided for passing atomized oil feed and diluent material 
obtained as herein provided to the distributor pot and nozzles for 
spraying the atomized oil fog into contact with upflowing catalyst 
particles in annular section 16 thereby initiating the formation of an 
upwardly flowing suspension of hydrocarbon feed-diluent-catalyst particles 
at a desired hydrocarbon conversion temperature. One method for forming 
the atomized oil feed as herein desired is to charge an oil stream by 
conduit 20 to which may be added viscosity reducing additives by conduit 
21 and water by conduit 22. From 1 to 5 weight percent of process water 
may be added by conduit 22. Conduits 20 and 22 comprising probe means 
inserted into conduit 20 may comprise an elongated slot in the downstream 
side of the probe to aid with mixing of the materials added with the oil 
feed and form an emulsion. The oil water mixture is then passed through 
flow control valve 24 permitting a pressure drop over the range of 5 to 20 
psig. The oil feed is then passed by conduit 26 to an orifice restriction 
28 of desired size which will direct a stream of the oil against a solid 
surface means 30 to form droplets of oil by impingement. A gaseous 
material such as steam or other suitable gaseous material herein 
identified is charged in an amount within the range of 1 to 10 weight 
percent by conduit 32 and passed through orifice restriction 34 before 
shearing contact with formed oil droplets and formed as above discussed to 
achieve a further atomization of the oil feed and form a fog or mist 
comprising oil droplets in the range of 10 to 500 microns. The atomized 
oil-diluent fog mixture thus formed is conveyed by conduit 12 to 
distributor pot 14. Conduit 12 may be surrounded by a heat dissipating 
sleeve not shown and purged with gaseous material to remove particles of 
catalyst and heat from the annular space between the sleeve and conduit 
12. In the arrangement above discussed the pot 14 is positioned above the 
catalyst standpipe inlet a sufficient distance to assure dense fluid 
catalyst phase movement up the riser to the annular space about 
distributor pot 14. In a specific embodiment the distributor pot is 
located about three riser diameters above the upper surface contact of 
conduit 4 with the wall of riser 2 at point 36 to assure the smooth 
catalyst flow desired. 
The arrangement of FIG. II is similar to that of FIG. I except that conduit 
12' is shown curved and penetrates the wall of riser 2' preferably above 
the regenerated catalyst standpipe inlet so that the mass of catalyst 
particles in the riser between annular section 16' and ring 8' is in an 
upflowing dense fluid catalyst phase condition. Inlet conduit 12' 
terminates in a distributor pot 14' provided with feed injection nozzles 
in the upper closed surface thereof. In this specific arrangement the 
nozzles are arranged as shown in the top view of FIG. IV. However, in 
either FIG. I or FIG. II the arrangement of nozzles employed may be either 
of that shown in FIGS. III and IV. The apparatus arrangement of FIG. II 
thus is used in a manner similar to that discussed with FIG. I except for 
the changes above noted. In either of these arrangements the fluidizing 
gas charged by ring 8 or 8' is sufficient to achieve a linear superficial 
velocity at least equivalent to the minimum fluidization velocity of the 
catalyst employed and generally in the range of about 0.1 to about 0.5 
feet per second. 
FIG. III diagrammatically shows a nozzle 18 arrangement or pattern which 
may be employed with the atomized oil distributor pot 14 of either FIG. I 
or II. In this arrangement equal numbers of nozzles 18 are equally spaced 
but staggered with respect to one another on two different diameter 
circles. The nozzles are sloped generally outwardly from the riser axis an 
amount sufficient to permit oil contact with the wall of the riser in the 
absence of catalyst flow not less than 4 feet above the upper surface 
level of the distribution pot. 
FIG. IV departs from the nozzle arrangement pattern of FIG. III in that a 
much smaller number of larger diameter nozzles 38 are employed on a single 
diameter circle in conjunction with an axially located nozzle. The plan 
views of FIGS. III and IV are interchangeable in the arrangements of FIGS. 
I and II. Also more or less nozzles may be employed in either of these 
arrangements which will improve vaporized oil contact with catalyst 
particles. 
In the nozzle arrangement of FIG. III, the arrangement is designed to 
achieve a hollow spray of atomized oil feed in diluent material which has 
to be penetrated by upflowing particles of catalyst to form a desired high 
temperature suspension mixture thereof. This method of contact appears to 
provide a more even contact between atomized and vaporized oil feed and 
inhibits substantially if not completely, catalyst and coke accumulation 
on the wall of the riser. The nozzle arrangement of either FIG. III or IV 
are positioned on the upper surface of a distributor pot of a size and 
shape providing little restriction to desired catalyst particle flow 
thereabout. Thus, the cross-sectional area of the annular section between 
the distributor pot and the riser wall should not be less than the 
cross-sectional area of the catalyst standpipe and preferably is greater 
than the standpipe cross-sectional area. Thus the pot 14 of FIG. I may 
occupy from 20 to about 40 percent of the riser cross-sectional area with 
minimum effect on desired upward flow of catalyst particles. In addition, 
as above suggested, the distributor pot is located on a plane below the 
regenerated catalyst standpipe flow control valve to reserve the static 
head achieved by the standpipe catalyst and dense fluid mass of catalyst 
in the bottom portion of the riser beneath the distributor pot. The 
distributor pot 14 is ideally designed and shaped to minimize catalyst 
flow disturbance upwardly and about the pot to optimize mixing of oil 
droplets, diluent and catalyst. This is achieved by employing a 
distributor pot derived from a cone with a 30 degree apex. To achieve 
desired nozzle exit velocity, it is proposed to pass an atomized 
oil-diluent mixture through the conduit to the distributor pot at a linear 
velocity preferably not exceeding more than half of the desired nozzle 
exit velocity. Thus the atomized and vaporized oil-diluent mixture passed 
through conduit 12 of FIG. I at a velocity of about 150 feet per second 
would be discharged from provided nozzles at a velocity of about 300 feet 
per second in one specific example. Other higher and lower velocity 
parameters may be employed with success depending on the feed processed. 
It has been postulated here before in the prior art that the liquid oil 
outlet velocity should match the superficial velocity of the vaporized 
uncracked oil material in the riser reactor. It has been observed 
recently, however, that in fact the feed inlet velocity can be much higher 
than previously thought possible and up to as high as about 350 or 400 
feet per second without encountering any noticeable adverse effects on the 
operation since the atomized oil feed expands extremely rapidly due to 
pressure drop and substantially instantaneously upon discharge in the 
riser cross-section. It has been further observed that a diluent such as 
steam in the atomized oil feed should be injected at a rate high enough to 
at least fluid support the catalyst particles and the velocity may be as 
low as 6 feet per second based on riser cross-section without adverse 
effects. 
Referring now to FIG. V by way of example there is shown an arrangement of 
apparatus particularly suitable for using and accruing the results of the 
improved operating concepts of this invention. That is to say, a two-stage 
regeneration operation is provided which permits obtaining high 
temperature catalyst particles by effecting the second stage of 
regeneration at a higher temperature than employed in a first stage 
operation in the manner taught in copending application Ser. No. 169086 
filed July 15, 1980 and now allowed. In this apparatus arrangement of FIG. 
V there is shown two separate regeneration zones 40 and 42 stacked one 
above the other with the lowermost zone 40 comprising a first-stage of 
dense catalyst bed regeneration and the uppermost zone 42 comprising the 
second stage of dense catalyst bed regeneration. The upper regeneration 
zone is refractory lined to withstand temperatures above 1400.degree. F. 
and more usually at least 1500.degree. or 1600.degree. F. during dense 
fluid bed regeneration of catalyst particles to remove residual coke from 
the catalyst with oxygen containing regeneration gas. Hot CO.sub.2 rich 
flue gases with entrained particles of catalyst are removed from the top 
of regenerator 42 by a "T" shaped refractory lined conduit means and 
provided with cyclone separating means on the end of each radiating arm of 
the "T". There may be 2, 3 or 4 radiating arms provided for this purpose. 
The hot CO.sub.2 rich flue gases are separated from entrained catalyst 
fines in a refractory lined cyclone separating zone 44 from which flue 
gases are recovered by conduit 46. Separated catalyst fines are recycled 
to the regenerator by dipleg 48. High temperature regenerated catalyst in 
the range of 1400.degree. to 1800.degree. F. is withdrawn from bed 50 and 
passed on to a stripping zone 52 wherein the catalyst is stripped 
countercurrently with inert stripping gas introduced by conduit 54. 
Stripping gas is recovered from the stripper by conduit 56 for return to 
the upper regenerator 42. The hot regenerated catalyst is passed by 
standpipe 58 to flow control valve 60 and thence by conduit 62 to a bottom 
portion of riser reactor 64 wherein it is initially retained as an 
upflowing relatively dense fluid mass of catalyst particles in relatively 
low velocity fluidizing gaseous material suitable for the purpose. Such 
gaseous material may be CO.sub.2, steam, light normally gaseous 
hydrocarbons and mixtures of such components. An atomized oil mixture with 
gaseous diluent obtained as discussed above with respect to either FIG. I 
or II is charged to a distributor pot by conduit 66 for distribution by 
nozzle arrangements of either FIG. III or IV and contact with upflowing 
catalyst as particularly discussed above. The suspension thus formed at a 
desired elevated hydrocarbon conversion temperature at least equal to and 
preferably above the end boiling point of the oil feed moves upwardly 
through the riser under catalytic cracking or conversion temperature 
conditions for a time generally restricted to less than about 4 seconds 
before discharge separation at the upper end of the riser contact zone. 
Means for separating the suspension discharged from the riser may be 
selected from any one of a number of different arrangements disclosed in 
the prior art, it being preferred to employ one providing the most 
efficient separation means. A hood 66 or other suitable arrangement may be 
positioned over the upper open end of the riser as shown in the drawing or 
a butterfly-looking appendage may be employed in conjunction with openings 
in the riser wall as shown in the copending application above identified. 
On the other hand, the top of the riser may terminate in radiating arms to 
which cyclone separation means are attached much in the same manner 
discussed above with respect to flue gas recovery and separation from 
regenerator 42 but absent not needed refractory lining. In the arrangement 
of the drawing hydrocarbon vapors and gaseous diluent material initially 
separated from suspension forming catalyst particles are passed through 
cyclone separation means represented by cyclone 68 from which vaporous 
material is recovered by conduit 70 and separated catalyst particles are 
recovered by dipleg 72 for passage to a collected bed of catalyst 74. 
Stripping gas such as steam is charged to a lower portion of bed 74 by 
conduit 76. The stripped catalyst is then conveyed by standpipe 78 to 
valve 80 and thence to catalyst bed 82 comprising a first stage of 
catalyst regeneration in regenerator 40. Oxygen containing regeneration 
gas is charged to a lower portion of bed 82 by conduits 84 and 86. The 
regeneration of the catalyst is accomplished in bed 82 is one of 
relatively mild regeneration below about 1400.degree. F. but sufficiently 
elevated to remove a substantial portion of hydrocarbonaceous deposits of 
catalytic cracking effected in riser 64. Catalyst thus partially 
regenerated is conveyed from a lower portion of bed 82 upwardly through a 
riser conduit 88 with oxygen containing gases such as air introduced by 
hollow stem plug valve 90 and into a bottom portion of catalyst bed 50. 
Additional oxygen containing gas may be added to a lower portion of bed 50 
by conduit means 92. Flue gas products of catalyst regeneration in 40 are 
subjected to cyclone separation to remove catalyst fines before recovery 
by conduit 94. Generally such flue gas will be CO rich because of the 
operating conditions employed in regenerator 40 and may be used to 
generate steam or power in downstream equipment not shown. 
The operation of a unit design similar to that discussed above with respect 
to FIG. V has been most successful in that the riser pressure drop has 
been found to be less than normally experienced heretofore. There is 
substantially less dry gas and coke make and the pressure drop in the 
first 10 feet of the riser reactor is less than 50% of the riser pressure 
drop thereby showing that excellent mixing of atomized oil feed and 
catalyst particles has been achieved. The improved results of the cracking 
operation here described are particularly achieved when processing an oil 
feed with a crystalline zeolite containing catalyst of equilibrium 
activity employing: 
A nozzle exit velocity of 300 feet per second 
A riser outlet velocity of 62 feet per second 
Feed rate of 18000 BPD 
Steam equal to 5 weight percent 
C/O ratio of 5.5 
A riser pressure drop of 2.0 psig 
Having thus generally described the improved method and means of this 
invention and discussed specific embodiments in support thereof, it is to 
be understood that no undue restrictions are to be imposed by reasons 
thereof except as defined by the following claims.