Vented riser

An improved ballistic separation device results from surrounding the downstream end of a progressive flow reactor or riser reactor with a concentric conduit that is in fluid communication with a cyclone separator and optionally in fluid communication with dipleg take-offs. The device may also include a bevelled lip or projection at the axial opening of the progressive flow reactor.

CROSS REFERENCE TO RELATED CASES 
The following related cases may contain information or make reference to 
prior act that is material to the instant application: 
Ser. No. 744,998 (U.S. Pat. No. 4,066,533); Ser. No. 800,780 (U.S. Pat. No. 
4,070,159); Ser. No. 361,661 (U.S. Pat. No. 4,424,116); Ser. No. 533,371; 
Ser. No. 263,394 (U.S. Pat. No. 4,390,503); Ser. No. 438,074 (U.S. Pat. 
No. 4,495,063); Ser. No. 521,504; Ser. No. 378,578 (U.S. Pat. No. 
4,477,335). 
BACKGROUND OF THE INVENTION 
This invention relates to an apparatus for separating solid particulates 
from a gaseous effluent. More specifically, the invention is concerned 
with efficient separation of very small fluidized catalytic or 
non-catalytic particles from a gaseous effluent comprising said particles 
and treated carbo-metallic hydrocarbons. 
In the contacting of hydrocarbons, extensive use is made of circulating 
fluidized beds. The apparatus employed for such systems as fluid catalytic 
cracking of hydrocarbon oils comprises a contacting zone, a disengaging 
zone, a regeneration zone and means to circulate solids, and vapors. The 
apparatus of this invention centers on the disengaging zone in which fluid 
contacting material is rapidly separated from a gaseous or vaporous 
effluent. 
A very effective contacting zone for hydrocarbon conversion is an elongated 
conduit such as found in a riser cracking zone. The riser cracker zone 
features rapid intimate contact of fluidized catalyst particles with hot 
oil vapors as the material progressively moves within the zone. The 
vaporous effluent components are quickly and substantially separated from 
the catalyst particles near the downstream exit of the zone. A discussion 
of prior art methods and apparatus used to carry out this separation of 
solid particulates from vapors is given in the section entitled PRIOR ART, 
which follows immediately hereinafter. 
PRIOR ART 
U.S. Pat. No. 4,070,159 (1978) and U.S. Pat. No. 4,066,533 (1978) both 
assigned to Ashland Oil, Inc. and represented in part in FIG. 2 disclose 
an apparatus and method for the removal of solid disperoids from gases 
wherein a separation means such as a cyclone is in direct communication at 
an upstream location with an open vented riser. 
U.S. Pat. No. 4,219,407 (1980) assigned to Mobil Oil Corporation discloses 
as a riser cracking operation wherein an improved method for separating 
vapors from entrained catalyst solids is employed. A mixture of vapors and 
particulates which have been induced to exit from a riser reactor zone are 
induced to flow outwardly then downwardly. The curved flow path imposed 
upon the effluent from the riser gives rise to a moment that concentrates 
the particulates in the mixture of vapors and particulates along a surface 
which imposed the the curved path downstream of the riser. The process is 
very similar to that disclosed in U.S. Pat. No. 4,313,910 discussed 
hereinafter. 
U.S. Pat. No. 4,295,961 (1981) and U.S. Pat. No. 4,364,905 (a division of 
'961) assigned to Standard Oil Company (Indiana) and represented in part 
in FIGS. 4 and 5 disclose apparatus and methods for fluid catalytic 
cracking which utilizes the same flow reversing means of separation as 
discussed in U.S. Pat. No. 4,310,489. 
U.S. Pat. No. 4,310,489 (1982) assigned to Standard Oil Company (Indiana) 
discloses an apparatus for catalytic cracking of hydrocarbons. The 
apparatus uses an enclosed vented riser to carry out a primary separation 
wherein the direction of a mixture of vapors and particulates are caused 
to reverse direction. Cracked hydrocarbons are withdrawn laterally from 
the downwardly flowing mixture. The separation process disclosed involves 
reversing the direction of flow of a mixture of hydrocarbons and 
particulates, preferably to a downstream direction by conducting the 
mixture through a flow reversing zone. conducting the mixture through a 
flow reversing zone. 
U.S. Pat. No. 4,313,910 (1982) assigned to Shell Oil Company discloses an 
apparatus for separating gas from a particulate stream. A mixture of 
particulates and gas exit from an open conduit such as a riser and are 
diverted by a wall surface such as a deflecting surface which causes the 
mixture particles and gas to travel in a curved path which leads to a 
concentration of accelerated particles along the wall surface which 
induces the curved path. In the preferred embodiment, the curved path 
directs the particles in a downward direction into a disengaging chamber. 
The vapors substantially separated from the downward directed particles 
are then picked up indirectly with cyclones or other separation means 
within the disengaging chamber from a dilute phase above the dense phase 
of particulates which have collected at the bottom of the disengaging 
vessel. There is no ballistic separation in the sense intended by this 
specification, wherein the vapors are induced to move laterally with 
respect to the direction of flow of a mixture of particulates and vapors. 
U.S. Pat. No. 4,318,800 (1982) assigned to Stone and Webster Engineering 
Corporation discloses an improved thermal regenerative cracking apparatus 
and process. Separator efficiency was improved by causing vapor components 
to move in a flow path involving a 180.degree. turn. Further it was 
disclosed that the flow path must be essentially rectangular and the 
relationship between barrier height and the sharpness of the U-bend in the 
gas flow was very significant. 
U.S. Pat. No. 4,394,349 (1983) assigned to Standard Oil Company (Indiana) 
discloses an apparatus for fluidized catalytic cracking of a hydrocarbon 
feedstock. The apparatus involves a riser reactor and a collar positioned 
about the axis defined by the downstream end of the reactor. The collar is 
positioned in close proximity to, but not in contact with, the riser 
reactor so that an annular space is defined between the riser reactor and 
the collar. The collar has a diameter greater than the diameter of the 
riser, but is spaced away from the riser so as not to be in contact with 
the riser in order to avoid expansion problems. The significant difference 
between the riser disclosed in '349 and the instant invention is the fact 
that the "collar" of the instant invention surrounds the riser progressive 
flow conduit without directly interacting with effluent after it has 
emerged from the open end of the riser. This point is discussed in more 
detail hereinafter. 
U.S. Pat. No. 4,390,503 (1983) assigned to Ashland Oil, Inc. and 
represented in part in FIG. 3 discloses a vented riser having as described 
throughout this specification an open cup with closed base which surrounds 
a riser conduit. In fluid communication with this open cup with closed 
base is a conduit which is adapted for connection to a second separation 
means such as a cyclone. 
There are several patents which have used prior art embodiments of vented 
risers assigned to Ashland Oil, Inc. These U.S. Pat. Nos. are: 4,066,533; 
4,070,159; 4,390,503; 4,424,116 and 4,435,279. 
While an open ended riser tube has many demonstrated advantages, efficiency 
is reduced by the tendency for a portion of the separated solids in the 
disengaging zone to be reentrained and carried back into the open end of a 
riser or progressive flow reactor. 
Accordingly, it is an object of this invention to avoid or lessen the 
tendency for reentrained solid particulates to enter a riser or conduit 
leading to a cyclone separator means used in conjunction with the riser or 
progressive flow reactor. 
SUMMARY OF THE INVENTION 
Broadly, this invention involves a means for separating particles from 
vapors. Mixtures of vapors and particles can arise from a variety of 
processes. For example, the instant invention has been found to be 
especially useful in separating cracking catalysts from hydrocarbon 
product vapors such as arise in the catalytic cracking of carbo-metallic 
oils, discussed in more detail in this specification. 
Other processes which the improved ballistic separation of the instant 
invention can be used are: separation of fluid-bed reforming catalyst 
particles containing precious metal or non-precious metal oxides; 
separation of ash from gaseous products in coal liquefaction and 
gasification; separation of coke fines from vaporous products in 
Flexicoking processes such as licensed by Exxon Research and Engineering 
Company; separation of fluid bed catalysts from vaporous products which 
arise during the preparation of acrylonitriles in processes such as 
developed by Sohio; separation of fluidized bed catalysts from reaction 
products of oxidation, alkylation, or ammidoxidation; separation of 
sawdust from air arising during wood pulp processing; and separation of 
fluid catalytic cracking catalysts from hydrocarbon products such as in 
the processes licensed by Research and Development Company, UOP, Inc. or 
M. W. Kellogg Company. 
In the embodiment, there is a disengaging chamber, a transport means such 
as a progressive flow reactor having a downstream end which is totally 
within the disengaging chamber, and a conduit chamber surrounding at least 
a portion of said downstream end of the transport means. Of critical 
importance to the proper functioning of the invention is that the mixture 
of particulates and vapors exiting from the axial opening in the 
downstream end of the transport means do not directly impinge on or 
interact with the conduit chamber to any substantial degree. This fact 
provides the basis for asserting that there is a significant departure 
from the invention disclosed in U.S. Pat. No. 4,394,349 ("'349") (1983). 
In '349, the downstream conduit that corresponds to the conduit chamber 
surrounding the instant invention, unlike the instant invention, directly 
and substantially impacts and controls the flow pattern of the mixture of 
vapors and particulates after they have exited from the riser or 
progressive flow reactor. (See FIG. 14 and the discussion corresponding 
thereto.) 
Still, another embodiment of this invention involves the fact that the 
walls of the conduit chamber surrounding at least a portion of the 
downstream end of the progressive flow reactor is in certain 
circumstances, preferably planar, e.g. a conduit having a rectangular or 
square shape in cross-section. (See discussion of FIG. 8.) 
Still a third embodiment of this invention involves using a dipleg takeoff 
which is in fluid communication with a downstream exit from the conduit 
chamber. 
Still one additional variation of the instant invention involves having a 
lip projection surrounding the downstream axial opening of the progressive 
flow reactor conduit. An example of such a projection is discussed with 
respect to FIG. 10. However, the use of such projections on any of the 
other embodiments disclosed in FIGS. 6, 7, 8, and 9 is an obvious 
variation in light of the hereinafter discussion with respect to FIG. 10 
and is intended to be part of the instant invention. Such a projection is 
preferably used with a vertical axial opening as opposed to a downwardly 
directed axial opening.

In FIG. 1, there is disclosed a hydrocarbon conversion reactor 43 and 
regenerator 36. The reactor comprises a riser 20, a disengaging chamber 
22, cyclones 30, a stripper zone 32 and conduits 34 and 38 which 
interconnect riser reactor 20 and regenerator 36. Regenerator 36 takes in 
regenerator gas, e.g. oxygen-containing gas, through conduit 52 passes it 
through carbonaceous coated catalysts and removes flue gasses through 
conduit 54 for later processing. 
Briefly, the riser reactor 20 and regenerator 36 of FIG. 1 operate as 
follows. Optionally, steam may be introduced through conduit 46 and mixed 
with either a hydrocarbon feed or lift gas from conduit 42 and introduced 
through conduit 50 into riser 20. Regenerated catalyst is introduced 
through conduit 38 into a lower portion of riser 20 for mixture with 
incoming gasses entering through conduit 50. A mixture of catalyst with 
gas from conduit 50 are accelerated up riser 20 and brought into contact 
with feeds entering conduits 42, and 44, and/or 48. Multiple feed 
injection ports are available in the riser so as to control contact time. 
More than one type of feed may be introduced through the different feed 
injection points. Catalysts and vapors move up conduit 20 providing a 
contact time of no more than about 3 to 5 seconds. Catalyst and vapor exit 
through the downstream end 24 of riser 20 into disengaging chamber 22. 
Since the catalyst solid particles have a greater inertia than the vapor 
components, there is a greater tendency for the catalyst particles to 
continue in a straight line as they exit from riser 20. However, the vapor 
components can be induced more easily to move in a transverse direction to 
the direction established by the axial opening of riser 20. Referring to 
FIG. 6, the vapors are induced to move into conduit chamber 26 defined by 
conduit wall 28 on one side and the exterior surface 31 of conduit 20. The 
vapors having entered chamber 26 are removed therefrom through conduits 27 
and then into cyclones 30 shown in FIG. 1. 
The mixture of solids and vapors which enter into cyclone 30 are further 
separated into particulates and vapors in ways which are conventionally 
known and understood in the cyclone art. The vapors exit from cyclones 30 
through conduits 51 and then into plenum chamber 53. The particulates, 
meanwhile, exit through diplegs 154 into a dense phase bed in stripper 
zone 32. 
Within stripper zone 32, there are stripper vanes 35 that permit a certain 
amount of agitation and movement of catalyst particles as they are brough 
into contact with steam which enters through conduit 40. 
The steam stripped carbonaceous coated catalyst is removed from stripper 
zone 32 through conduit 34 within which there is a flow control valve 37 
and then into regenerator 36. The carbonaceous coated particles are then 
regenerated by contact with an oxygen-containing gas which burns off 
substantially all of the carbonaceous deposits from the particles. 
Regenerated particles are removed from regenerator 36 through conduit 38 
within which there is a flow control valve 39 for return to riser 20 where 
the process is repeated. 
In FIG. 1, there is a two stage regenerator disclosed. Initially, stripped 
catalysts, e.g. by steam, from hydrocarbon conversion reactor 43 is 
transported through conduit 34 passed flow control valve 37 into upper 
regeneration zone 166. Oxygen containing gas, e.g. air with or without 
steam, enter through conduit 178 to a plenum chamber 170. Alternatively, 
the oxygen containing gas can enter directly into the dilute phase above 
the dense phase bed 192 and then through passage ways 172 in to upper zone 
166. Oxygen containing gas that enters through plenum chamber 170 is 
distributed into upper zone 166 through conduits 176 for maximum 
dispersion of oxygen containing gas throughout the bed in upper zone 166. 
Flue gases above the dense phase bed in upper zone 166 enter cyclone 180 
wherein entrained particles are separated from the flue gas. Particulate 
components separated in cyclone 180 are returned to dense phase bed in the 
upper regenerator and vapor components of flue gas are transported to 
plenum 182. Flue gases are then removed from plenum 182 by means of 
conduit 54 upon which additional processing may be carried out in a down 
stream operation. 
A portion of the partially regenerated catalyst from upper dense phase bed 
166 is transported through conduit 186 through a cooler 188 then through 
conduit 190 having a flow control valve 193 into dense phase bed 192. A 
second portion of partially regenerated catalysts from upper dense phase 
bed 166 is transported thru conduit 194 past flow control valve 195 into 
dense phase bed 192. Passage of partially regenerated catalysts directly 
from the upper zone of dense phase bed 166 to the lower zone dense phase 
bed 192 thru conduit 194 is done in order to permit temperature control of 
the lower zone in conjunction with flow of catalysts thru catalyst cooler 
188. Additional oxygen containing gas enters through conduit 52 into a 
distribution point then through a grid 198 for uniform distribution 
through dense phase bed 192. Flue gases from lower zone exit through 
pathway 172 then into the upper dense phase bed 166. After additional 
oxidation and carbonaceous deposit removal, vapors exit regenerator 36 
through conduit 54. 
Examples of carbo-metallic oils or hydrocarbon feedstocks that may enter 
riser 20 through conduits 42, 44 and 48 are ones containing 650+ boiling 
materials, plus metals such as copper, nickel, vanadium, and the like. 
Vacuum gas oil, recycle light cycle oil or vacuum resides are common 
examples of such oils. Steam at a pressure and temperature of about 50-450 
pounds per square inch ("psi") and about 250.degree.-450.degree. F., 
respectively, can be introduced through conduits 40 and 46. 
Examples of the particles or catalysts that are conventionally used in a 
riser reactor such as disclosed in FIG. 1 are process clays which may 
contain a zeolite. In catalytic cracking the particle size of the catalyst 
are preferably in the range of about 40 to about 120 microns. Of course, 
the larger the catalyst particles, the more efficient is the separation 
achieved in a ballistic type process exemplified in the instant invention. 
Regenerator 36 is usually at a temperature in the range of about 
1200.degree.-1600.degree. F. 
FIGS. 2, 3, 4, 5 and 13 represent examples of the PRIOR ART. FIG. 2 shows 
the downstream end of riser 60 with a takeoff conduit 62. This arrangement 
for the downstream end of a riser is disclosed in U.S. Pat. Nos. 4,066,533 
and 4,070,159. FIG. 3 is an improvement over the riser shown in FIG. 2 and 
is disclosed in U.S. Pat. No. 4,390,503. This is the downstream end of a 
conduit 64 axially venting into a disengaging vessel 71. A cup-like 
chamber 66 surrounds the downstream end of conduit 64. From cup-like 
chamber 66 there is a conduit 68 which leads to a cyclone or other 
separation means (not shown). 
FIGS. 4 and 5 are disclosed in U.S. Pat. No. 4,295,961. Within separation 
or disengaging chamber 71 of FIG. 4, there is a riser 72 with a downstream 
end of which is surrounded by a cap 70. Cap 70 defines a flow reversal 
zone 58. A mixture of catalyst and vapors exiting vented riser 72 enter 
flow reversal zone 58 and are induced to reverse direction of flow into a 
downly directed mixture of vapors and particulates. From the downwardly 
directed flow indicated by arrows 61, the vapor components having lower 
inertia are induced to exit through conduits 69 to a separator means 79. 
In FIGURE 5, in place of cap 70, at the end of a riser 72, there is a flow 
reversal conduit 63 at the end of a riser 65. The purpose of flow reversal 
conduit 63 is to induce a downwardly directed flow (indicated by arrows 
67) of a mixture of vapors and particulates that have risen through 
conduit 65. The vapor components of the downwardly directed mixture of 
vapors and particulates because of lower inertia are induced 
preferentially to move through conduits 73 into separation means or 
cyclones 79. 
FIG. 6 shows in more detail, an enlarged vented riser of the instant 
invention disclosed in FIG. 1. Surrounding riser 20 is a conduit 28. 
Through a wall of conduit 28 are conduits 27 which lead to a cyclone 
separator means 30 (not shown). Chamber 26 or conduit chamber 26 is 
defined by the exterior surface of riser 20 and the interior surface of 
conduit 28. Phantom wall 29 indicates that the relative height of riser 20 
as compared to conduit 28 may vary. In operation, as a mixture of vapor 
and entrained particulates exits from riser 20 part of the mixture 
consisting substantially of vapor components only is induced to move in a 
curved path indicated by arrows 21 into entrance 23 and then out through 
conduits 27 to cyclone separator means 30 not shown. Because of the 
difference in inertial characteristics of vapor components versus 
particulate components, it is far more difficult for the particulates 
components to change direction than the vapor components. 
Length L shown in FIG. 6 is of such a length that the tendency for 
particulate flow from exit 25 to opening 41 into conduit 27 is 
substantially reduced. It has been found that the minimum length of L from 
entrained particle exit 25 to vapor take-off exit 41 shown in FIG. 6 is 
preferably at least about two (2) riser diameters, D, shown in FIG. 6 and 
still more preferably greater than two (2) riser diameters. Some benefits 
were found at low riser velocities, e.g. below thirty (30) feet per second 
of an L/D ratio of 17 as compared to 9. (See graph of FIG. 12.) 
Also at lower velocities, e.g. below about 30 feet/second, there is little 
difference in efficiency between a standard open cup such as shown in FIG. 
3, having a L/D equal to 0.3 and the same standard cup, but with bottom 
removed or open shown in FIG. 6, i.e. about 98.5% versus about 99.0%. This 
is shown in FIG. 15 with the curve for dots of circled 2's versus that 
curve for circled 1's. A cup with L/D equal to 0.3 at low velocity with a 
bottom (standard cup of FIG. 3) is more efficient than with its bottom 
removed or open (cup of FIG. 6). However, at increasing velocities, e.g. 
above about 30 feet/second, a totally unexpected phenomena occurs; 
efficiency of the standard cup (FIG. 6 with bottom open) drops off 
dramatically whereas that percent efficiency of a standard cup with bottom 
closed (shown in FIG. 3) does not drop off but increases to about 99.8% at 
40 feet/second and above. 
With L/D ratios of about 9 or greater, and the bottom of the cup removed, 
there is an improvement at lower speeds, e.g. less than 30 feet/second, 
and surprisingly no fall off in efficiency at speeds above 30 feet/second 
(see curves for circled 3's and 4's of FIG. 15). 
In commercial operations involving vented risers, streams comprising vapors 
and particulates usually move at a velocity greater than 40 feet/second 
through the riser, except for a brief but important period of time during 
start-up. 
There has not been found any limit as to the ultimate length. However, 
lengths in excess of two riser diameters do not seem to improve operating 
efficiencies significantly at velocities above thirty (30) feet per 
second. The importance of length L, defined as the approximate distance 
between the opening of exit 25 and the beginning of vapor take-off opening 
41, is thatany tendency of any particulates in a mixture of vapors and 
particulates to enter through exit 25 and leave through conduit 27 can be 
reduced substantially. Further benefits from having L with the length 
provided in this specification may involve a reduced tendency to build up 
coke or other carbonaceous deposits in the annular area between the vented 
riser and concentric pipe in situations where there is a high content of 
precursors, which can form coke or other carbonaceous deposits readily. 
FIG. 8 is the top planar view along line 8--8 of FIG. 6 which discloses an 
alternate embodiment of the instant invention wherein conduit wall 28 is 
square as opposed to cylindrical. It has been found that in certain 
circumstances at certain velocities that a square wall 28 performs better 
than a cylindrical wall. However, in general, either a cylindrical or 
rectangular e.g., square, conduit wall 28 may be used. FIG. 8 uses the 
same numbering system for the same corresponding parts shown in FIG. 6. 
The purpose of FIG. 14 is to define two areas, area A and area B. For 
optimum operation of risers in keeping with the instant invention, it has 
has been discovered that the ratio of area B to area A is preferably in 
the range of about 0.5 to about 1.25, and more preferably about 0.75 to 
about 1. This ratio of areas seems to apply to areas which arise from 
concentric circular conduits as well as rectangle or square conduits 
surrounding a circular conduit. 
FIG. 7 discloses how an embodiment of the instant invention can apply to 
the prior art embodiment disclosed in FIG. 4. In FIG. 7, there is 
disclosed a riser 72, a reversing zone vessel 70 contained within a 
disengaging chamber 71, conduit wall 74 and conduit 83 to cyclone 76. 
Briefly, in operation a mixture of vapor and particulates rises through 
conduit 72 and exits axially into zone 58 defined by reversing chamber 70. 
The entire mixture of vapors and particulates undergoes a flow reversal as 
indicated by arrows 77. The mixture of particulates and vapors having 
undergone a flow reversal of 180.degree. and exits through opening 81 
defined by the interior wall of flow reversing chamber 70 and the outer 
surface of conduit 72. Since vapor components of the mixture of 
particulates and vapors exiting through opening 81 have a much lower 
inertia than particulate components, they can be more readily induced to 
flow along the path indicated by arrow 75 into entrance 78 and then 
through conduit 83 to a cyclone 76. The drop in pressure created by 
cyclone 76 within conduit 83 induces the flow path indicated by arrow 75. 
Vapor components are required to undergo a change in direction of 
180.degree. before they are able to enter entrance 78 leading to conduit 
83 and cyclone 76. It is important to note that in this embodiment the 
mixture of vapors and particulates which leaves through axial opening 81 
is in no way impeded by the conduit wall 74. The mixture of particulates 
and vapors enters directly into the disengaging chamber defined by wall 
74. In other words there is no component of the conduit wall 74 such as 
phantom wall 82 which significantly extends beyond the opening 81. This, 
however, does not preclude or is not intended to preclude from 
consideration from within the scope of this invention of a small extension 
of conduit 74 as indicated in phantom outline by phantom extension wall 
82. However, as phantom wall 82 either extends more and more beyond 
opening 81, or more and more below the opening, then entrainment of solids 
begins to occur more and more. Increased entrainment results in low 
separation efficiency. 
FIG. 9 discloses how an embodiment of the instant invention applies to the 
prior art exemplified in FIG. 5. Wherever possible, elements which are the 
same in both FIGS. 5 and 9 have been given the same numbers. 
Unlike the embodiment of the prior art disclosed in FIG. 5, there is a wall 
conduit 86 which surrounds at least part of the downwardly directed 
conduit 85 of FIG. 5. Also, instead of conduit 73 in fluid communication 
with conduit 85, conduit 73 is in fluid communication with conduit 86. 
Conduit 86 defines an annular space between the exterior surfaces of 
conduit 85 and the interior surfaces of conduit 86. There are two openings 
to the annular space immediately surrounding conduit 85 which are openings 
84 and 95. The mixture of vapors and particulates from riser 65 are caused 
to change direction by conduits 63 and 85 so as to flow in the direction 
shown by arrow 67. Because of the difference in inertia between 
particulates and vapor components, the vapor components are induced more 
easily to flow in a direction indicated by arrows 97. The particulates 
tend to continue in a downwardly directed path of flow within disengaging 
chamber or vessel 71. Of critical importance to the embodiment disclosed 
in FIGURE 9 is the presence of an additional opening 84. This opening 
permits an alternate flow path for stripper gas introduced by stripper gas 
conduits 99. As is common practice in the art, carbonaceous coked catalyst 
are generally steam stripped prior to return to a regenerator (not shown) 
through conduit 101. Stripper gas entering through conduits 99 creates a 
flow pattern within disengaging chamber 71 that, but for the change in 
structure provided by conduit 86, would result in additional entrained 
particles entering cyclones 79 through conduits 73. Of still more 
importance is the fact that conduit 86 can extend a short distance beyond 
the downstream opening of conduit 85. This is indicated by the phantom 
wall extension 87. Preferably, wall 86 does not extend beyond the opening 
of conduit 85 nor is well 86 much shorter than conduit 85, for the same 
reasons concerning particulate reentrainment discussed with respect to 
FIG. 7. 
In FIG. 10, there is a riser 105, conduit wall 90, a conduit 92 to a 
cyclone not shown, diplegs 96 with a valve 98. The valve 98 is pivotally 
attached at pivot point 100 so as to permit only unidirectional flow from 
within diplegs 96 to dense phase bed 102. Briefly, operation of the 
embodiment disclosed in FIG. 10 is as follows. Vapors and particulates 
rising through riser 105 exit axially into a disengaging chamber (not 
shown) in FIG. 10. Flow path of the material exiting from riser 105 is 
indicated by arrows 104 and 106. Arrow 104 indicates the flow path of 
vapor components induced to flow in a path transverse to the axial path 
indicated by arrow 106. Arrow 106 represents the flow path followed by 
particulate components substantially free of vapor components. The 
difference in the inertial character of the vapor components versus the 
particulate components permits the pressure drop caused by the cyclones 
(not shown) within conduit 92 to cause vapor components indicated by arrow 
104 to move into conduit chamber 91 defined by conduit wall 90 and riser 
105, and then out though conduit 92 in the direction indicated by arrow 
110. Since there are some particulates that remain entrained within the 
vapor components indicated by arrow 104, these are permitted to flow in 
the direction of arrow 108 into dipleg 96 then into foot portion 107 and 
then through valve 98 into dense bed 102. It is important to note that the 
chamber defined by conduit 90 and riser 105 from which vapors are 
withdrawn through conduit 92 does not significantly or to any substantial 
degree impede or interact directly with the axial flow of components from 
riser 105. Although it is within the intent of this invention to permit 
some of conduit 90 to some degree to extend, as indicated by phantom lines 
94, above at least a small portion of the axial opening 89, if phantom 
wall 94 extends too far past the axial opening 89 of riser 105 then some 
additional components of entrained particulates will be induced to flow 
into chamber 91 defined by the exterior surface of riser 105 and the 
interior surfaces of wall 90. Accordingly, there is a point of diminishing 
returns as to the advantage of having phantom wall 94 extend any 
substantial degree above axial opening 89. Alternatively, if the opening 
into conduit chamber 92 is much below axial opening of conduit 105, then 
some additional components of entrained particles will begin to occur with 
greater and greater frequency as the opening to conduit chamber 91 is 
increasingly below axial opening 89. 
Optionally, there may be added a beveled lip 103 to riser 105. Bevelled lip 
or protection 103 impacting the velocity of the flow of vapor and 
particulates leads in certain situations to a somewhat better separation 
of particulates from vapors. The length of protection 103 is approximately 
of about 1/2 the distance of the inside diameter, D, of the riser 105 and 
is preferably at an angle of about 5 to about 30 degrees, preferably about 
10 to about 20 degrees from the axial-direction defined by the conduit 
walls of riser 105. The relevant angle is shown as the Greek Symbol, 
Theta, in FIG. 10. 
FIG. 11 discloses a top planar view along line 11--11 of FIG. 10. Elements 
of each FIGURE are numbered consistently. In the embodiment of FIG. 11, 
conduit 90 is not shown. Conduit 90 can be in other shapes other than a 
cylinder such as for example a square or rectangle as discussed in FIG. 8. 
FIG. 12, discloses graphs which are discussed in section entitled Examples. 
In FIG. 13, the downstream portion of a riser 200 is within a disengaging 
zone (not shown) to which there is a downstream conduit 202 from which 
there is a conduit 204 in fluid communication with interior zone 205 of 
conduit 202. Conduit 204 is in fluid communication with a cyclone 
separator means (not shown). Operation of the prior art embodiment in FIG. 
13 is as follows. A mixture of vapor and particulate components moving in 
the direction shown by arrow 203 is diverted inwardly by projection 206. 
The mixture then enters zone 205 within conduit 202. The vapor components 
of that mixture are caused by a differential pressure preferably because 
of much lower inertia for the vapor components as compared to the 
particulate components to be diverted transversely through conduit 204 to 
a cyclone (not shown). 
Of importance to the operation of the prior art embodiment of FIG. 13 is 
that the entire mixture of vapor and particulate components must enter 
zone 205 prior to diversion transverse to the direction established by 
axial opening of conduit 200. There is a space 208 between conduit 202 and 
200 to avoid problems that were indicated in the reference (U.S. Pat. No. 
4,394,349) to otherwise arise from thermal expansion. 
EXAMPLES 
The concept of the invention was evaluated in a testing unit. The 
experimental apparatus used to test this concept is a clear plastic model 
of a cracking unit consisting of a riser, disengager/stripper, two stage 
regenerator and connecting standpipes. The model is operated at room 
temperature under vacuum. Room air enters the unit at the bottom of the 
riser and base of the regenerator through regulating valves and is 
discharged from the disengaging chamber and regenerator, respectively. All 
vaporous effluents are metered and exited through a vacuum pump. Room air 
can also enter the unit in other locations such as the stripper zone if 
necessary to simulate steam stripping in a commercial unit. The riser 
diameter of this unit is 1/2 inch with the other dimensions scaled 
appropriately. 
A test is conducted by passing a specific amount of fluidized solid up the 
riser over a specific time and with a specific riser gas velocity. Solids 
lost from the disengaging chamber are recovered in an external cyclone 
with a sealed dipleg. Separation efficiency is determined as: 
##EQU1## 
Where: Loss=solids collected in the external cyclone dipleg. 
Load=amount of catalyst passed up the riser. 
Three vented cup risers were built out of Lucite acrylic sheet tubing. 
Vented cup riser A, B and C had a double pipe design. The ratio of L to 
inside diameter of riser, D, for risers A-C are, respectively, about 9.4, 
9, and 17. See FIG. 6 and corresponding discussion for the definition for 
L and D. 
Generally, the tests with stripper air were less efficient than the tests 
without. The stripper air could have decreased efficiency because more air 
was introduced into the reactor and created a larger RXR/cyclone DP. 
The concentric or double pipe vented riser A is illustrated in FIG. 6. It 
is a modification of the vented riser exemplified in FIG. 3. Medium 
velocity achieved the best efficiency. (See FIG. 12.) 
______________________________________ 
EFFICIENCY STUDIES 
DOUBLE PIPE VENTED CUP RISER A 
Time Cat. Lost 
Flow Rate Air Velocity 
(sec) 
(g) (lbs/sec) (ft/sec) Efficiency 
______________________________________ 
342 28.0 .0574 43 99.68 
232 15.9 .0846 34 99.82 
220 73.3 .0897 25.8 98.50 
______________________________________ 
Double pipe vented riser B as shown in FIG. 6 is similar to vented riser A 
shown in FIG. 3, except that the bottom has been removed to allow trapped 
catalyst to fall freely. (See FIG. 6.) Although medium velocity was still 
the most efficient, the overall efficiency decreased. 
______________________________________ 
EFFICIENCY STUDIES 
DOUBLE PIPE VENTED CUP RISER B 
Time Cat. Lost 
Flow Rate Air Velocity 
(sec) 
(g) (lbs/sec) (ft/sec) Efficiency 
______________________________________ 
616 43.7 .0320 43 99.51 
264 17.0 .0746 34 99.81 
255 133.8 .0770 25.8 98.50 
______________________________________ 
Double pipe vented cup riser C has the longest cup. By increasing the 
length of the cup, the resistance of air flow up the cup increased and the 
efficiency increased. Also 50% of the bottom of the cup was closed. 
______________________________________ 
EFFICIENCY STUDIES 
DOUBLE PIPE VENTED CUP RISER C 
Time Cat. Lost 
Flow Rate Air Velocity 
(sec) 
(g) (lbs/sec) (ft/sec) Efficiency 
______________________________________ 
499 43.8 .0402 43 99.51 
228 17.8 .0836 34 99.80 
226 25.7 .0832 25.8 99.71 
______________________________________ 
EXAMPLE SHOWING EFFICIENCIES AS A FUNCTION OF VELOCITY 
FIG. 15 discloses graphs of the standard open cup vented riser in 
comparison to cups without any bottom (concentric pipe configuration) with 
L/D ratios from 0.3 to 17.0. Efficiency measurements were made on the 
standard open cup vented riser as shown with the circles containing the 
number 2. The efficiency increases with increasing velocity until about 33 
feet/second and then the efficiency remains constant. The L/D ratio of the 
standard cup is 0.3. By removing the bottom of the cup as shown by the 
circles with the number 1, the efficiency, although higher at lower 
velocities, rapidly decreases with increasing velocity. 
Since commercial operations use riser velocities in general greater than 40 
feet/second and up to 100 feet/second the conclusion one would draw from 
the above experiments is that removing the bottom of the cup is not 
advantageous. 
Additional experiments were made with the open cup with the bottom removed 
(called the concentric pipe vented riser) with L/D ratios of 9.0, 9.4 and 
17.0. As shown on the graph by the circled 3's and 4's, these 
configurations gave high efficiencies at all velocity ranges checked. In 
unit start-up situations, riser velocities are usually initially low. The 
concentric pipe separators would provide high efficiency separations in 
this region as well as the higher velocity operating ranges. 
EXAMPLE SHOWING EFFICIENCY AT CONSTANT VELOCITY AS A FUNCTION OF L/D 
FIG. 16 shows the effect of varying the L/D ratio at different velocities. 
At the lower velocities, below 30 feet/second, the efficiencies do not 
appreciably change with changing L/D for the open cup/open bottom vented 
riser. The advantage of increasing L/D becomes apparent, however, at 
velocities above about 30 feet/second. 
That efficiency is not significantly changed for velocities of from 25 to 
30 feet/second with a changing L/D ratio of from 0.3 to 17 is demonstrated 
by the relatively flat or horizontal nature of curves for circled 3's and 
4's corresponding respectively to velocities 30 and 25. 
However, for velocities of 30 and 35, curves for circled 2's and 3's 
respectively, there is a dramatic improvement in efficiency as a function 
of L/D from about a ratio of 2 and above. The benefits reaching a maximum 
for a L/D about 6 and above. 
The data used in plotting graphs shown in FIG. 15 is given in the following 
Table for FIG. 15. 
TABLE FOR FIG. 15 
______________________________________ 
Conventional Open Cup Vented Riser 
Efficiency Measurements with no stripper 
air and no simulated cyclones. 
L/D = .3 
Time, sec Velocity Efficiency 
Time, sec Velocity Efficiency 
ft/sec % ft/sec % 
______________________________________ 
272 25.6 98.58 228 29.9 99.31 
251 25.6 98.69 207 29.9 99.28 
299 25.6 99.60 217 29.9 99.25 
291 25.6 99.49 
286 25.6 98.84 
average 99.04 average 99.28 
322 34.1 99.71 429 38.4 99.79 
306 34.1 99.81 407 38.4 99.63 
310 34.1 99.89 343 38.4 99.87 
296 34.1 99.82 406 38.4 99.81 
381 38.4 99.77 
average 99.81 average 99.77 
Opencup vented riser test 
with bottom of cup open 
L/D - .3 
471 42.7 99.83 320 17.9 99.43 
569 42.7 99.85 405 28.5 99.59 
468 42.7 99.76 341 28.5 99.69 
511 42.7 99.87 466 31.5 99.22 
average 99.83 302 31.5 99.40 
1191 38.0 98.38 
1455 42.5 97.79 
The above data shows the steep 
decline in efficiency as the 
velocity is increased 
______________________________________ 
Specific compositions, methods, or embodiments discussed are intended to be 
only illustrative of the invention disclosed by this Specification. 
Variation on these compositions, methods, or embodiments, such as 
combinations of features from various embodiments, are readily apparent to 
a person of skill in the art based upon the teachings of this 
Specification and are therefore intended to be included as part of the 
inventions disclosed herein. 
Any reference to patents made in the Specification is intended to result in 
such patents being expressly incorporated herein by reference including 
any patents or other literature references cited within such patents.