FCC riser with transverse feed injection

Hydrocarbon feedstock is dispersed in an FCC riser by directing jets of atomized feed droplets into a flowing stream of catalyst particles in a direction substantially perpendicular to the axis of the riser. By directing the feed into the riser in a substantially perpendicular direction feed is more quickly dispersed across the entire cross section of the riser. By quickly dispersing feed the mixture of hydrocarbons and catalyst particles is completely mixed after traveling only a short distance along the riser from the point of feed introduction. Reducing this contact zone length improves the quality of riser products by eliminating variations in the contact time between the feed and catalyst. In addition to the short contact zone length this invention also combines the desirable features of catalyst pre-acceleration and feed atomization. The apparatus used for practicing this invention may also include a central strike surface in the riser to prevent erosion of the riser wall from the radially directed feed jets.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to the dispersing of liquids into 
fluidized solids. More specifically this invention relates to a method and 
apparatus for atomizing liquid into fine droplets and dispersing the 
droplets into a suspension of fluidized solids. A specific aspect of this 
invention relates to the contacting of fluidized catalyst particles with a 
liquid hydrocarbon wherein the liquid hydrocarbon is atomized into a 
dispersion of fine droplets and injected into the stream of fluidized 
catalyst particles. 
2. Description of the Prior Art 
There are a number of continuous cyclical processes employing fluidized 
solid techniques in which carbonaceous materials are deposited on the 
solids in the reaction zone and the solids are conveyed during the course 
of the cycle to another zone where carbon deposits are at least partially 
removed by combustion in an oxygen-containing medium. The solids from the 
latter zone are subsequently withdrawn and reintroduced in whole or in 
part to the reaction zone. 
One of the more important processes of this nature is the fluid catalytic 
cracking (FCC) process for the conversion of relatively high-boiling 
hydrocarbons to lighter hydrocarbons boiling in the heating oil or 
gasoline (or lighter) range. The hydrocarbon feed is contacted in one or 
more reaction zones with the particulate cracking catalyst maintained in a 
fluidized state under conditions suitable for the conversion of 
hydrocarbons. 
It has been a long recognized objective in the FCC process to maximize the 
dispersal of the hydrocarbon feed into the particulate catalyst 
suspension. Dividing the feed into small droplets improves dispersion of 
the feed by increasing the interaction between the liquid and solid. 
Preferably, in hydrocarbon conversion droplet sizes become small enough to 
permit vaporization of the liquid before it contacts the solids. 
It is well known that agitation or shearing can atomize a liquid 
hydrocarbon feed into fine droplets which are then directed at the 
fluidized solid particles. A variety of methods are known for shearing 
such liquid streams into fine droplets. 
U.S. Pat. No. 3,071,540 discloses a feed injection apparatus for a fluid 
catalytic cracking unit wherein a high velocity stream of gas, in this 
case steam, converges around the stream of oil upstream of an orifice 
through which the mixture of steam and oil is discharged. Initial impact 
of the steam with the oil stream and subsequent discharge through the 
orifice atomizes the liquid oil into a dispersion of fine droplets which 
contact a stream of coaxially flowing catalyst particles. 
U.S. Pat. No. 4,434,049 shows a device for injecting a fine dispersion of 
oil droplets into a fluidized catalyst stream wherein the oil is first 
discharged through an orifice onto an impact surface located within a 
mixing tube. The mixing tube delivers a cross flow of steam which 
simultaneously contacts the liquid. The combined flow of oil and steam 
exits the conduit through an orifice which atomizes the feed into a 
dispersion of fine droplets and directs the dispersion into a stream of 
flowing catalyst particles. 
The injection devices of the '540 and '049 patents rely on relatively high 
fluid velocities and pressure drops to achieve atomization of the oil into 
fine droplets. Providing this higher pressure drop burdens the design and 
increases the cost of equipment such as pumps and exchangers that are 
typically used to supply liquid and gas to the feed injection device. The 
need to replace such equipment may greatly increase the cost of 
retrofitting an existing liquid-solid contacting installation with such an 
injection apparatus. 
Other methods for atomizing liquid feeds with gaseous material are shown in 
U.S. Pat. Nos. 3,152,065 and 3,654,140. FIG. 2 of U.S. Pat. No. 3,654,140 
shows an injection device that imparts a tangential velocity to an oil 
stream to promote its mixing with a stream of steam which is injected into 
the oil outside the injection device. In U.S. Pat. No. 3,152,065 an 
injection device adds a tangential velocity to an annular stream of oil 
that flows around a central conduit. Steam passing through the center 
conduit contacts the oil at the distal end of the injector. Steam and oil 
then pass through an orifice which further atomizes the oil and 
distributes it into a dispersion of fine droplets. In these devices, the 
tangential velocity of oil in combination with the expansion of the steam 
is relied on to provide the energy for atomizing the oil. 
U.S. Pat. No. 4,717,467 shows a method for injecting an FCC feed into an 
FCC riser from a plurality of discharge points. The discharge points in 
the '467 patent do not radially discharge the feed mixture into the riser. 
Another useful feature for dispersing feed in FCC units is the use of a 
lift gas to pre-accelerate the catalyst particles before contact with the 
feed. Modern FCC units use a pipe reactor in the form of a large, usually 
vertical, riser in which a gaseous medium upwardly transports the catalyst 
in a fluidized state. Catalyst particles first enter the riser with zero 
velocity in the ultimate direction of riser flow. Initiating or changing 
the direction of particle flow creates turbulent conditions at the bottom 
of the riser. When feed is introduced into the bottom of the riser the 
turbulence can cause maldistribution and variations in the contact time 
between the catalyst and the feed. In order to obtain a more uniform 
dispersion, the catalyst particles are first contacted with a lift gas to 
initiate upward movement of the catalyst. The lift gas creates a catalyst 
pre-acceleration zone that moves the catalyst along the riser before it 
contacts the feed. After the catalyst is moving up the riser it is 
contacted with the feed by injecting the feed into a downstream section of 
the riser. Injecting the feed into a flowing stream of catalyst avoids the 
turbulence and backmixing of particles and feed that occurs when the feed 
contacts the catalyst in the bottom of the riser. A good example of the 
use of lift gas in an FCC riser can be found in U.S. Pat. No. 4,479,870 
issued to Hammershaimb and Lomas. 
The addition of lift gas to initially accelerate the catalyst can also be 
used for a variety of purposes such as treating the catalyst particles 
prior to contact with the feed and varying the residence time of the feed 
in the riser. There are many references which teach, for various reasons, 
the mixing of hot regenerated FCC catalyst with various relatively light 
materials prior to contact of the catalyst with the FCC feedstock. Thus, 
in U.S. Pat. No. 3,042,196 to Payton et al. beginning with a light cycle 
oil, progressively heavier components are added to an upflowing catalyst 
stream in a reactor riser so as to use a single catalyst and a single 
cracking zone to convert the elements of a crude oil. In U.S. Pat. No. 
3,617,497 to Bryson et al. a light gas oil is mixed with a diluent vapor 
such as methane or ethylene at or near the bottom of a reactor riser with 
hot regenerated catalyst, introduced at the same point in the riser or 
very close downstream, with the mixture then contacted with heavy gas oil 
at the top of the riser so as to enhance gasoline yield. In U.S. Pat. No. 
3,706,654 to Bryson et al., naphtha diluent may be added to the bottom of 
a reactor riser to aid in carrying upwardly into the riser the regenerated 
catalyst stream. In U.S. Pat. No. 3,849,291 to Owen it is disclosed that a 
gasiform diluent material comprising C.sub.4 + hydrocarbons and 
particularly C.sub.5 + hydrocarbons may be used to form a suspension with 
freshly regenerated catalyst which suspension is caused to flow through an 
initial portion of a riser reactor before bringing the hydrocarbon 
reactant material in contact therewith in a downstream portion of the 
reactor so as to achieve a very short residence time (1 to 4 seconds) that 
the hydrocarbon is in contact with the catalyst suspension in the riser 
reactor (catalyst residence time). U.S. Pat. No. 3,894,932 to Owen 
discusses contacting the FCC conversion catalyst with a C.sub.3 -/C.sub.4 
rich hydrocarbon mixture or an isobutylene rich stream before contact with 
gas oil boiling range feed material in an initial portion of the riser 
(catalyst to hydrocarbon weight ratio from 20 to 80) so as to upgrade the 
C.sub.3 -C.sub.4 material to a higher boiling material. U.S. Pat. No. 
4,422,925 to Williams et al. discusses passing a mixture of hydrocarbons, 
such as ethane, propane, butane, etc., and catalyst up through a riser 
reactor at an average superficial gas velocity within the range from about 
40 to about 60 feet per second (12.2-18.3 meters/sec), with a catalyst to 
hydrocarbon weight ratio of about 5 to about 10 so as to produce normally 
gaseous olefins. In U.S. Pat. No. 4,427,537 to Dean et al. there is shown 
catalyst particles mixed with a fluidizing gas, such as a gaseous 
hydrocarbon, charged to a bottom portion of a reactor riser to promote or 
provide for a smooth non-turbulent flow up the riser of a relatively low 
velocity dense flow of catalyst particles. 
There are additional references which show use of a lift gas in 
non-catalytic systems. For example, in U.S. Pat. No. 4,427,538 to 
Bartholic, a gas which may be a light hydrocarbon is mixed with an inert 
solid at the bottom part of a vertical confined conduit and a heavy 
petroleum fraction is introduced at a point downstream so as to vary the 
residence time of the petroleum fraction in the conduit. Similarly, in 
U.S. Pat. No. 4,427,539 to Busch et al., a C.sub.4 minus gas is used to 
accompany particles of little activity up a riser upstream of charged 
residual oil so as to aid in dispersing the oil. 
The use of feed atomization and lift gas, to pre-accelerate catalysts, have 
been combined in FCC risers to obtain the benefit of a more uniformly 
dispersed feed across the cross section of a riser reaction zone. While 
both the catalyst pre-acceleration obtained from lift gas and feed 
atomization are desirable features for improving feed injection, these 
features are usually combined in a manner that requires a relatively long 
contact time before the feed is completely mixed with the catalyst 
particles. The typical devices for the atomization of the feed will inject 
the feed into the riser at high velocities typically greater than 30 
meters per second. It has been the practice to aim the exit stream from 
the atomization device in a principally parallel direction to the flow of 
catalyst particles. Since the catalyst and gas mixture passing by the 
distribution nozzles has a typical velocity of less than 12 meters per 
second the feed and catalyst must travel along the riser for a distance 
called the axial contact length before the feed and catalyst achieve a 
uniform velocity and thorough mixing. The atomization nozzles are usually 
positioned with their nozzles near the wall of the riser. Positioning the 
feed nozzles near the wall of the riser keeps pipe elements out of the 
central portion of the riser which would introduce turbulence and undo 
part of the work of the catalyst pre-acceleration zone. Part of the 
non-uniformity in the mixing over the axial contact zone is the result of 
feed having to travel from the wall of the riser to the center of the 
riser. As the length of the axial contact zone is decreased, better 
initial mixing of the catalyst and feed results. Therefore, it would be 
highly desirable to have a method and apparatus for contacting FCC 
catalysts with a hydrocarbon feed that includes the features of catalyst 
pre-acceleration feed atomization and minimum axial contact zone length. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a method and apparatus for 
pre-accelerating catalyst particles in an FCC riser and contacting the 
pre-accelerated catalyst with an atomized feed over the entire cross 
sectional area of the riser within an axial contact zone of reduced 
length. 
This objective is achieved by the use of a transverse feed injector for 
contacting an axial flow of catalyst particles with an atomized 
hydrocarbon feed that is injected through a plurality of nozzles that are 
aimed into the riser at a target cylinder in a direction substantially 
perpendicular to the flow of catalyst. More specifically, the regenerated 
catalyst and a lift gas are used to accelerate the catalyst of a reactor 
riser in a catalyst pre-acceleration zone. The axial flow of catalyst 
passes a ring of atomization nozzles that circle the wall of the reactor 
riser and have orifice openings with radially projecting centerlines. The 
catalyst nozzles are aimed such that the centerlines are normal to the 
axis of the riser or within 25.degree. of normal to the axis of the riser. 
By fully atomizing the feed and directing it transversely across the riser 
a fog of feed droplets form a feed interface across the riser. The feed 
interface produces rapid radial dispersion so that nearly all the catalyst 
at all portions of the riser cross section are simultaneously contacted 
with the feed. A high degree of atomization of the feed allows rapid 
vaporization of the feed so that there is a minimum slippage between the 
catalyst particles and the feed vapors. As a result, the axial contact 
zone length is short. Concerns over erosion of the riser are overcome by 
the use of a target cylinder into which the nozzles are aimed. Thus, this 
invention provides three desired features: catalyst pre-acceleration, feed 
atomization and a minimum axial contact zone length. 
Accordingly in a specific embodiment this invention is an apparatus for 
contacting a fluidized FCC catalyst with an FCC feedstock. The apparatus 
includes an elongated riser conduit having an upstream end and a 
downstream end. Means are provided for adding FCC catalyst to the upstream 
end of the riser and a nozzle in the upstream end of the riser adds a 
gaseous medium to the riser for transporting the FCC catalyst along the 
riser. A circumferential inlet band is located in the riser between the 
upstream end and the downstream end. A plurality of orifices are spaced 
symmetrically around the circumferential band of the riser and the 
orifices have openings that are aimed radially inward toward the 
centerline of the riser along a centerline having an angle of less than 25 
degrees from a plane normal to the centerline of said riser. A target 
cylinder is coaxially aligned with the riser and extends above and below 
the center point. Means are provided for communicating the FCC feedstock 
to the orifices and discharging the feedstock through the orifices with 
sufficient pressure to atomize the feed. 
In a more limited embodiment this invention is an apparatus for contacting 
an FCC catalyst with an FCC feedstock in a substantially vertical riser 
conduit having an upper end and a lower end. A regenerator catalyst 
standpipe is in communication with the lower end of the riser and 
transfers FCC catalyst to the riser. A fluidizing gas nozzle located in 
the lower end of the riser passes fluidizing gas into the riser for 
fluidizing the FCC catalyst and transporting a stream of the FCC catalyst 
up the riser. An annular feed distribution chamber inside the riser 
extends circumferentially around and is located between the upper and 
lower ends of the riser. An inner wall of the chamber borders the stream 
of FCC catalyst and a circumferential feed inlet band extends around the 
inner chamber wall. At least two feed conduits communicate with the 
chamber for suppling FCC feedstock and an atomizing fluid to the chamber. 
A plurality of baffles are located in the chamber for mixing the feedstock 
and atomizing fluid. A plurality of discharge nozzles are symmetrically 
spaced around the circumferential inlet band at a spacing of no more than 
75 mm apart. Each discharge nozzle defines an orifice. The orifices have 
substantially horizontal centerlines that project inwardly toward a center 
point located along the centerline of the riser. A target cylinder is 
coaxially aligned with the riser and extends above and below the center 
point. 
Additional objects, embodiments and details of this invention can be 
obtained from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION 
This invention will be described in the context of an FCC process for the 
catalytic cracking of hydrocarbons by contact with a fluidized catalyst. 
In a typical FCC process flow, finely divided regenerated catalyst leaves a 
regeneration zone and contacts a feedstock in a lower portion of a reactor 
riser zone. FIG. 1 shows a reactor 10 with a vertical riser 12 and a lower 
riser portion 14 into which a regenerator standpipe 16 transfers catalyst 
from the regenerator. Feed enters the riser through a group of feed 
nozzles 18 and a feed inlet band 20. While the resulting mixture, which 
has a temperature of from about 200.degree. C. to about 700.degree. C., 
passes up through the riser, conversion of the feed to lighter products 
occurs and coke is deposited on the catalyst. The effluent from the riser 
is discharged from the top of the riser through a disengaging arm 22 into 
a disengaging space 24 where additional conversion can take place. The 
hydrocarbon vapors, containing entrained catalyst, are then passed through 
one or more cyclone separators 26 to separate any spent catalyst from the 
hydrocarbon vapor stream. The separated hydrocarbon vapor stream is passed 
from an outlet nozzle 28 into a fractionation zone known in the art as the 
main column wherein the hydrocarbon effluent is separated into such 
typical fractions as light gases and gasoline, light cycle oil, heavy 
cycle oil and slurry oil. Various fractions from the main column can be 
recycled along with the feedstock to the reactor riser. Typically, 
fractions such as light gases and gasoline are further separated and 
processed in a gas concentration process located downstream of the main 
column. Some of the fractions from the main column, as well as those 
recovered from the gas concentration process may be recovered as final 
product streams. The separated spent catalyst from cyclones 26 passes into 
the lower portion of the disengaging space through dip legs 30 and 
eventually leaves that zone passing through a stripping zone 32 in which a 
stripping gas, usually steam, enters a lower portion of zone 32 through a 
distributor ring 34 and contacts the spent catalyst purging adsorbed and 
interstitial hydrocarbons from the catalyst. A series of baffles 35 in the 
stripping zone improves contact between the catalyst and stripping gas. 
The spent catalyst containing coke leaves the stripping zone through a 
reactor conduit 36 and passes into a regeneration zone where, in the 
presence of fresh regeneration gas and at a temperature of from about 
620.degree. C. to about 760.degree. C., combustion of coke produces 
regenerated catalyst and flue gas containing carbon monoxide, carbon 
dioxide, water, nitrogen and perhaps a small quantity of oxygen. Usually, 
the fresh regeneration gas is air, but it could be air enriched or 
deficient in oxygen. Flue gas is separated from entrained regenerated 
catalyst by cyclone separation means located within the regeneration zone 
and separated flue gas is passed from the regeneration zone, typically, to 
a carbon monoxide boiler where the chemical heat of carbon monoxide is 
recovered by combustion as a fuel for the production of steam, or, if 
carbon monoxide combustion in the regeneration zone is complete, the flue 
gas passes directly to sensible heat recovery means and from there to a 
refinery stack. Regenerated catalyst which was separated from the flue gas 
is returned to the lower portion of the regeneration zone which typically 
is maintained at a higher catalyst density. A stream of regenerated 
catalyst leaves the regeneration zone, and as previously mentioned, 
contacts the feedstock in the reaction zone. 
Catalysts that can be used in this process include those known to the art 
as fluidized catalytic cracking catalysts. Specifically, the high activity 
crystalline aluminosilicate or zeolite-containing catalysts can be used 
and are preferred because of their higher resistance to the deactivating 
effects of high temperatures, exposure to steam, and exposure to metals 
contained in the feedstock. Zeolites are the most commonly used 
crystalline aluminosilicates in FCC. 
It has been found that the method of contacting the feedstock with the 
catalyst can dramatically affect the performance of the reaction zone. 
Ideally the feed is instantaneously dispersed as it enters the riser over 
the entire cross-section of a stream of catalyst that is moving up the 
riser. A complete and instantaneous dispersal of feed across the entire 
cross section of the riser is not possible, but good results have been 
obtained by injecting a highly atomized feed into a pre-accelerated stream 
of catalyst particles. However, the dispersing of the feed throughout the 
catalyst particles takes some time, so that there is some non-uniform 
contact between the feed and catalyst as previously described in 
connection with the axial contact zone. Non-uniform contacting of the feed 
and the catalyst, for the time it is in the axial contact zone, exposes 
portions of the feed to the catalyst for longer periods of time which can 
in turn produce overcracking and reduce the quality of reaction products. 
Therefore, a preferred riser contact zone will include at least the three 
following features: catalyst pre-acceleration to provide a moving stream 
of catalyst, feed atomization to provide good dispersion of the feed 
through the catalyst particles, and a short axial contact zone length to 
keep a relatively constant contact time between the feed and catalyst. 
Catalyst pre-acceleration is provided by injecting a gaseous medium into 
the bottom of the riser. This gaseous medium is often called lift gas. 
FIG. 1 shows a gas conduit 38 that is used to inject lift gas into the 
riser. Contact of the hot catalyst, entering the riser with a lift gas, 
accelerates the catalyst up the riser in a uniform flow regime that will 
reduce backmixing at the point of feed addition. Reducing backmixing is 
important because backmixing varies the residence time of hydrocarbons in 
the riser. Addition of the lift gas at a velocity of at least 1.8 meters 
per second is necessary to achieve a satisfactory acceleration of the 
catalyst. This invention does not require a specific lift gas composition. 
Steam by itself can serve as a suitable lift gas. However, the lift gas 
used in this invention is more effective when it includes not more than 10 
mol % of C.sub.3 and heavier hydrocarbons and is believed to selectively 
passivate active metal contamination sites on the catalyst to reduce the 
hydrogen and coke production effects of these sites. Selectively 
passivating the sites associated with the metals on the catalyst leads to 
greater selectivity and lower coke and gas yield from a heavy hydrocarbon 
charge. Steam may be used by itself as a gaseous medium or may be included 
with the lift gas. In addition to hydrocarbons, other reaction species may 
be present in the lift gas such as H.sub.2, H.sub.2 S, N.sub.2, CO and/or 
CO.sub.2. However, to achieve maximum effect from a lift gas, it is 
important that appropriate contact conditions are maintained in the lower 
portion of the riser. A residence time of 0.5 seconds or more is preferred 
in the lift gas section of the riser, however, where such residence time 
would unduly lengthen the riser, shorter residence times for the lift gas 
and catalyst may be used. A weight ratio of catalyst to hydrocarbon in the 
lift gas of more than 80 is also preferred. 
Once the catalyst is accelerated, feed is injected into the moving catalyst 
steam through a plurality of discharge points or nozzles located in a feed 
injector apparatus. The nozzles have restricted openings or orifices that 
divide the feed into small droplets. In order to disperse liquid feed into 
a dispersion of fine droplets, sufficient energy must be imparted to the 
liquid in order to break the liquid up into small droplets. The prior art 
has used an expanding gas or gaseous component such as steam in 
conjunction with another source of energy in order to break up the liquid. 
This other source of energy can consist of a high pressure drop for the 
gas and liquid mixture. In those cases where the gas and liquid are mixed 
and simultaneously discharged at high velocity, additional energy, usually 
in the form of pressure drop across a restricted opening, must be supplied 
to the liquid and gas mixture in order to adequately mix and homogenize 
the mixture before discharge. The supply of additional energy makes up for 
inadequate mixing so that a fine and uniform distribution of droplets will 
still be obtained outside the injector apparatus. It is also known that 
the pressure drop across a liquid injector can be reduced while still 
obtaining a good dispersion of fine liquid droplets by blending and 
homogenizing the liquid and gas sequentially in stages of increased mixing 
severity. The feed which enters the injection device will usually have a 
temperature below its initial boiling point but a temperature above the 
boiling point of the steam or gaseous hydrocarbons that enters the 
injection device along with the liquid. Whatever the relative composition 
of the liquid and gaseous components, a minimum quantity of gaseous 
material at least equal to 0.2 wt. % of the combined liquid and gaseous 
mixture, is usually commingled with the liquid entering the injection 
device. As the gaseous medium and liquid, usually steam and hydrocarbons, 
enter the injector apparatus, they tend to remain segregated. Therefore, 
this invention may pass the mixture through a mixing device such as one or 
more baffles to blend the hydrocarbon and steam mixture into a relatively 
uniform hydrocarbon and steam stream. By substantially uniform, it is 
meant that any major segregation between the liquid and gaseous component 
that would tend to deliver more liquid or gaseous medium to one section or 
another of the injector device is eliminated. This blending is typically 
mild and normally will add a pressure drop of less than 100 kPag to the 
system. 
The nozzle of the feed injector apparatus includes a restricted opening or 
orifice that directs the feed radially into the riser so that the feed is 
sprayed across the flowing stream of catalyst particles. The orifice has a 
restricted diameter that produces a pressure drop for atomizing the feed 
as previously described and imparting a velocity to the exiting feed which 
develops a jet along the axis of the orifice. This jet is aimed across the 
riser in a direction that is substantially perpendicular to the axis of 
the riser and the direction of catalyst flow. The jet shoots the feed 
droplets across the stream of catalyst. The radial velocity of the 
droplets bring feed droplets into contact with catalyst at the center of 
the riser at almost the same time as feed droplets that contact the 
catalyst near the wall of the riser. As a result, the axial contact zone 
has a very short length. The orifices are spaced closely around a 
circumferential band of the riser. Close spacing of the orifices increases 
the coverage of the droplets over the cross section of the riser. 
The angle at which the centerlines of the orifices are aimed is an 
important element of this invention. It is essential that the orifices 
impart a primarily radial velocity to the exiting feed. For this reason, 
the centerlines of the orifices make approximately a right angle with the 
centerline of the riser. It is not necessary that the orifice centerlines 
be kept completely perpendicular to the centerline of the riser. The 
centerlines may make an angle of .+-.25.degree. with a plane perpendicular 
to the centerline of the riser. But preferably the angle of the orifice 
centerlines deviate from such plane by an angle of less than 10.degree. 
and more preferably less than 5.degree.. FIG. 2 illustrates the angular 
range of the orifice opening centerlines. Angles are measured from a plane 
normal to the centerline of the riser conduit. Where the riser conduit 
extends vertically, the plane normal to the riser extends horizontally and 
is represented by section line 3--3 of FIG. 2. Line 44 represents a 
typical centerline of the orifice openings and shows the orifice openings 
aimed perpendicularly to the riser at an angle of 0.degree. from the 
horizontal plane. Line 44' shows the centerline of the orifice openings 
aimed downward at an angle A that can vary from 0.degree. to 25.degree. 
and line 44" shows the centerline of the orifice openings aimed upward at 
an angle B that can vary from 0.degree. to 25.degree. . The angle of the 
orifice centerlines may be angled slightly downward to compensate for the 
upward velocity of the catalyst so that the interaction of the axial 
catalyst velocity and the velocity of the radially directed feed form a 
horizontal interface across the riser where the catalyst initially 
contacts the feed. The orifice centerlines may also be angled slightly 
upward to direct radially deflected catalyst against a fixed portion of 
the riser wall and provide erosion protection as hereinafter explained. 
The orifice openings are designed to produce a stream of atomized feed 
droplets having a relatively high velocity of at least 15 meters per 
second with velocities of 30 meters per second or more being preferred. In 
order to obtain such velocity, feed passing through the orifice openings 
will require a pressure drop of at least 130-270 kPag. Higher pressure 
drops will produce a greater degree of atomization as well as higher 
velocities for the droplets exiting the orifices. While a greater degree 
of atomization has been found to be beneficial for purposes of feed 
dispersion, the higher velocities associated therewith can, in narrow 
risers, cause erosion of the riser and attrition of the catalyst. 
Therefore, it is usually desirable to keep the feed velocity below 60 m/s. 
The design of the nozzle end or orifice opening also contributes to the 
effective functioning of this invention. Production of a relatively small 
spray pattern from the end of the nozzle aids in dispersing feed mixture 
across the entire transverse cross-section of the reactor riser. 
Therefore, the ends of the nozzle have a restricted discharge opening in 
the form of a nozzle or slot that will spray the feed in a narrow pattern. 
Preferably, the total angle of this pattern in the vertical direction does 
not exceed 45.degree. and more preferably it does not exceed 20.degree.. 
The apparatus for practicing this invention is more fully illustrated in 
FIG. 2. Regenerated catalyst in an amount regulated by control valve 40 
enters the riser 14 through a regenerator standpipe 16 where it is 
contacted with the lift gas. The lift gas is introduced into the riser 
through gas conduit 38 having a plurality of nozzles 42 arranged about the 
top of the conduit to distribute the lift gas into the catalyst. Catalyst 
is transferred up the riser preferably for a distance equal to at least 4 
pipe diameters of the riser before it is contacted with the feed 
introduced by the feed injection apparatus 20 of this invention. 
The feed injection apparatus has a series of nozzles 42 that define orifice 
openings having centerlines 44 that extend in a direction perpendicular to 
the centerline of riser 12. Nozzles 42 are positioned in a circumferential 
band 46 with the discharge end of the nozzles located flush to the surface 
of circumferential band 46. 
Means are provided for distributing fluid to each nozzle 42. In one 
possible arrangement circumferential band 46 may be formed out of part of 
the wall of the riser and the means for distributing fluid will include 
external piping connected to each nozzle. In the embodiment shown in FIG. 
2 a chamber 48 distributes fluid to each of nozzles 42. Chamber 48 is 
defined by circumferential band 46, a frusto-conical reducer 50, a section 
52 of the wall of riser 14 and a top plate 54. Nozzles 18 communicate the 
FCC feed to the chamber 48. Frustoconical reducer 50 decreases the cross 
sectional area of riser 14 by a small amount to provide the annular volume 
for chamber 48. Reducer 50 should have a long length to provide a gradual 
change in riser diameter. Preferably the walls of section 50 will have at 
least a 1 in 4 slope. 
The jets of atomized feed drop produced by nozzles 44 have a potential to 
create erosion problems on the walls of riser 14. The impact of the feed 
droplets will impart a momentum to the catalyst particles and deflect the 
catalyst in a radial direction. If the radially deflected catalyst 
particles hit the wall of the riser they can rapidly erode the riser. In 
order to minimize the potential for erosion from radially directed 
catalyst particles, nozzles 42 are preferably located symmetrically about 
band 46 so that radial catalyst velocities associated with each of the 
jets are cancelled out by the radial catalyst velocities created by 
opposing jets as the centerlines converge at the centerpoint of the riser. 
In addition, as a stream of catalyst particles contacts the jets of 
atomized feed droplets, these jets are deflected in the manner 
approximated by flow lines 56. Because of this upward deflection any 
radially directed catalyst will strike the wall of riser 14 above 
centerlines 44. In order to protect the metal wall of the riser from 
possible erosion, a band of high density abrasion-resistant lining 58 is 
located on the inside of the riser wall above top plate 54. Compositions 
and methods for installing abrasion-resistant linings are well known to 
those skilled in the art of FCC piping designs. The lining will preferably 
have a thickness of at least 75 mm and will extend axially along the riser 
wall for a distance equal to at least one riser diameter. The upper end of 
abrasion-resistant lining band 58 is provided with a long tapered section 
60 to again provide a gradual change in the diameter of the riser 14. In 
many riser designs a high density abrasion-resistant lining having a 
thickness of 75 to 100 mm is used over the entire interior surface of the 
riser wall. In these instances a circumferential band of the lining can be 
left out at the desired location for the feed inlet nozzles in order to 
provide space for chamber 48. In these cases, there is no need to provide 
frusto-conical reducer 50 or the gradual taper 60. For further protection 
against erosion it is also preferred that an abrasion-resistant lining 
cover the surface of circumferential band 46 that faces the interior of 
the riser. 
As yet further protection against erosion FIG. 2 shows a target cylinder 62 
located along the centerline of riser 14. Target cylinder 62 provides a 
strike surface upon which all of centerlines 44 are directed. Any direct 
radial impact from the jet of atomized feed droplets or catalyst particles 
is deflected by target cylinder 62 before it can contact the wall opposite 
the nozzle. In this manner target cylinder 62 will further prevent erosion 
of the riser walls by deflecting and dissipating the radial momentum 
created by nozzles 42. Target cylinder 62 also has the added benefit of 
increasing the distribution of feed over the transverse section of the 
riser and further reducing the axial contact zone length. An 
abrasion-resistant lining covers the exterior surface of target cylinder 
62. A group of horizontally extending brackets 64 support target cylinder 
62 from the riser wall at a location upstream of nozzles 42. Target 
cylinder 62 has a top cone 66 and a bottom cone 68 to provide a gradual 
transition for the changes in flow area created by the addition of target 
cylinder 62. Again, target cylinder 62 will preferably extend above the 
centerline of nozzles 42 for a distance equal to at least one diameter of 
the riser. 
A cross sectional view of the preferred arrangement for the apparatus used 
in this invention is shown in FIG. 3. In order to improve the presentation 
the width of chamber 68 has been exaggerated in FIG. 3. Four feed nozzles 
18 communicate the hydrocarbon feeds to chamber 48. As the feed enters 
chamber 48 it first passes through a baffle 70. Preferably the feed will 
contain at least 2 wt. % steam and baffle 70 has a number of mixing 
nozzles 72 that impose a pressure drop on the feed mixture to mix it with 
the steam as it passes across baffle 70. Preferably nozzle 72 will impose 
a pressure drop of at least 100 kPag between nozzle 18 and chamber 48 to 
promote mixing of the feed and steam. This mixing improves the atomization 
of the feed when it passes through nozzle 42. Baffles 70 extend axially 
over the entire length of the chamber so that each baffle 70 defines a 
sub-volume 48' of annular chamber 48. 
Nozzles 42 are closely spaced around band 46 to provide complete coverage 
of atomized feed over the transverse cross section of the riser. In order 
to provide this complete coverage the nozzles will preferably be spaced no 
more than 75 mm apart. This means that for a relatively small FCC riser 
having an inner diameter of 600 mm there will be at least 24 nozzles 
spaced around the circumferential band 46. The jet lengths formed by the 
orifices are directly proportional to the velocity through the orifice and 
the size of the orifice. Therefore, in order to restrict the jet length it 
is preferable to use small orifice openings having a diameter of from 6 to 
20 mm. Using small orifice openings will in turn increase the number of 
nozzles. Thus larger risers may use 100 or more nozzles in circumferential 
band 46. 
FIG. 3 also shows that all of the nozzles are directed radially inward 
toward the centerline of the riser along orifice centerlines 44. In this 
manner all of the centerlines 44 converge on target cylinder 62 which is 
supported by support brackets 64.