Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CATALYTIC REACTIO~ CHAMBER FOR
GP~VITY-FLOWING CATALYST PARTICLES
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SPECIF~CATIO~
The presen-t invention is directed toward an im-
proved reaction chamber for effecting the cataly-tic con-
version of a hydrocarbonaceous reactan-t stream in a multi-
: ple-stage system wherein (i) the reactant s-tream flows
serially through the plurali-ty of reaction:zones, (ii) the
catalyst par-ticles are movable through each reaction ZQne
via gravity-flow and, (iii) catalyst particles are movable
via gravity from one zone to -the nex-t succeeding zone. More
particularly, the desc.ribed process technique is adaptable
for u-tiliza-tion in vapor-phase systems wherein -the conversi.on
reacti.ons are principally endothermic, and where the flow of
the hydrocarbonaceous reactant stream, with respect to the
downward direction of catalyst particle movement, is cocur-
rent and essentially radial.
Various types of multiple-stage reaction systems
¦ have found widespread utilization throughout the petroleum
and petrochemical industries, especially for hydrocarbon
conversion reactions. Multiple-stage reaction systems gen-
erally take one of two forms: (1) side-by-side configuration
with intermediate heating between the reaction zones, wherein
the reactant stream or mixture flows serially from one zone
to another zone; and, (2~ a stacked design wherein a single
reaction chamber, or more, contains the multiple catalytic
contact stages. Such reactor systems, as applied.to petroleum
refining, have been employed to effect numerous hydrocarbon
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conversion reactions including those which are prevalent in
catalytic reforming, ethylbenzene dehydrogenation to produce
¦ styrene and other dehydrogenation processes. Our invention
is specifically intended for utilization in those processes
where (1) the conversion reactions are effected in vapor-
phase and, (23 catalyst particles are downwardly movable via
gravity-flow; and where the reaction system exists in side-
by-side relation, where two or more catalytic - contact zones
are "stacked", or where one or more additional reaction zones
are disposed in a side-by-side relationship with the vertical
stack.
The present techni~ue contemplates the withdrawal
oE catalyst particles from a bottom portion of one reaction
zone and the introduction of fresh, or regenerated catalyst
particles into the top portion of a second reaction zone.
.,
The present technique is also intended to be applied to those
reaction systems wherein the catalyst is disposed as an an-
nular bed and the flow of the reactant stream, serially from
one zone to another, is perpendicular, or radial to the move-
ment of catalyst particles.
A radial-flow reaction system generally consists
of tubular form sections, having varying nominal cross-sec-
tional areas, vertically and coaxially disposed to form the
reaction vessel. Briefly, the system comprises a reaction
chamber containing a coaxially-disposed catalyst-retaining
screen, having a nominal, internal cross-sectional area less
.
than said chamber, and a perforated centerpipe having a nominal,
internal cross-sectional area which is less than the catalyst-
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retaining screen. The reac-tant stream is introduced, in
vapor-phase, into the annular-form manifold space created
between the inside wall of the chambex and the outside sur-
face of the catalyst-retaining screen. The lat-ter forms an
annular-form, catalyst-holding zone with the outside surface
of the perforated centerpipe, vaporous reactant flows lat-
erally and radially through the screen and catalyst zone into
the centerpipe and out of the reaction chamber~ Although the
tubular-form configuration of the various reactant components
may take any suitable shape -- e.g., triangular, square, ob-
long, diamond, etc. -- many design, `Eabrication and technical
considerations dictate the advantages of using components which
are suhstant:;ally circular in cross-section.
A ~lultiple-stage stacked reactor system, to which
the present invention is particularly adaptable, is that shown
in U. S. Patent No. 3,706,536. Transfer of the gravity-flow-
ing catalyst par-ticles, from one reaction zone to another,
as well as introduction of fresh catalyst particles and with-
drawal of used catalyst particles, is effected through the
utilization of a plurality of catalys~-transferj or withdrawal
conduits. Experience in the use of such systems, as well as
those where the reaction zones are disposed in a side-by-side
relationship indicates that high vapor flow through the an-
~- nular-form catalyst-holding sections results in catalyst par-
ticles being unable to move in the vicinity of the perforated
centerpipe, thereby creating stagnant catalyst areas where
the catalyst particles are prevented from assuming a downward~
unifor~ gravity-flow pattern. The stagnant catal~st eventually
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loses its effectiveness due to coke deposition, whereas in
a flowing configuration the aged catalyst would continually
be removed and replaced with newer, fresh catalyst~
A principal object of our inven-tion is to prevent,
or alleviate stagnant catalyst areas in a hydrocarbon con-
version system in which catalyst particles are movable via
gravity-flow. A corollary objective is to provide an improved
catalytic reaction chamber for utilization in a multiple-stage,
stacked reac-tor system in which catalyst particles in each
1~ reaction zone are movable via gravity-flow, and catalyst par-
. ticles flow from one zone to the next succeeding reac-tion
zone by way of gravity-flow.
ThereEore, in one embodiment, our lnvention pro-
vides a catalytic reaction charnber for ef:Eecting contact of
a reactant stream with catalyst particles which are (1) dis-
posed as an annular-form bed and, (2) downwardly movable
therethrough via gravity-flow, said reac-tion chamber compris-
ing, in cooperative relationship: (a) an outer per:Eorated
catalyst-retaining screen (i) concentrically disposed within
and, (ii) having a cross-sectional area less than said cham-
ber to provide a reactant stream manifold space therebetween;
~b) an inner perforated centerpipe (i) concentrically-dis-
posed within and, (ii) having a cross-sectional area less
than said catalyst-retaining screen to provide said annular-
form catalyst bed therebetween; (c) a plurali~y of catalyst
inlet conduits connected to the upper portion of said cham-
ber and communicating with said annular-form catalyst bed;
and, (d~ a plurality of vertically-positioned catalyst-trans-
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fer, or withdrawal conduits (i) circumferentially-disposed
substantially adjacen-t the outer surface of said per~orated
centerpipe, (ii) extending substantially the entire length
of said annular-form ca-talyst bed and, (iii) containing a
first plurality of apertures facing into said annular-form
catalyst bed and sized to permit catalyst particles to flow
therethrough.
Preferably, the catalyst-transfer, or withdrawal
conduits contain a second plurality of apertur~s facing said
perforated centerpipe and sized to inhibit the flow of cat-
alyst particles therethrough.
In a pre:Eerred embodiment, the apertures in the
catalyst-transfer conduits are disposed along the length
thereof and the conduits contain a plurality of internal in-
. 15 clined baffles, each one of which extends downwardly from
the uppermost periphery of each of the apertures in said
first pluraltiy.
Various -types of hydrocarbon conversion processes
utilize multiple-stage reactor systems, either in a side-by-
side configuration, as a vertically-disposed stack, or a com-
bination o~ a stacked system in side-by-side relation with
one or more separate reac-tion zones. Such systems may be
employed in a wide variety of hydrocarbon conversion reactions.
While our inventive concept is adaptable to many conversion
reactions and processes, -through the reactor system of which
. the cata.lyst particles are movable via gravity-~low, it will
~e further described in conjunction with the well known en~
dothermic catalytic reformlng process.
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Historically, cataly-tic reforming was effected in
a non-regenerative, fixed-bed sys-tem comprising a plurality
of reaction zones disposed in side-by-side relation. When
the cataly-tic composite had become deactived to the extent
that con-tinuous operation was no longer economically feas-
ible, the entire unit was shut-down and the catalyst regen-
erated in situ. Of a more recent vintage was the so-called
"swing bed" system in which an extra reactor was substituted
for one which was due to be placed off-stream for regeneration
purposes. Still more recently, multiple-stage reactor sys-
tems have been provided in which the catalyst particles flow,
via gravity, through each reaction zone. In a "stacked"
system, the catalyst particles also flow downwardly from one
catalyst-containing zone to another, and ultimately transfer
to a suitable regeneration system also preferably functioning
with a downwardly-moving bed of catalyst particles. In ef-
fect, the catalyst particles are maintained from one section
to another in a manner such that the flow of catalyst par-
ticles is continuous, at frequent intervals, or at extended
intervals, with the movement being con-trolled by the quan-tity
of catalyst withdrawn from the!last of the series of individual
reactlon zones.
U. S. Patent No. 3,470tO90 is illustrative of a
multiple-stage, side-by-side reaction system wlth intermediate
~ heating of the reactant stream which flows serially through
the individual reaction zones. Catalyst particles withdrawn
from any one of the reaction zones are transported to suit-
; able regeneration facilities. Thls type of system can be
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modified to the exten-t that the catalyst particles withdrawn
from a given reaction zone are transported to the nex-t suc-
¦ ceeding reaction zone, while the catalyst withdrawn from the
¦ last reaction zone may be transported to a suitable regen-
eration facility. The necessary modifications can be made
in the manner disclosed in U. S. Patent No. 3,839,1~7 in-
volving an inter-reactor catalyst transport method. Catalyst
transfer from the last reaction zone in the plurality to the
top of the catalyst regeneration zone is made possible through
the use of the technique illustrated in U. S. Patent No.
3,839,196.
A stacked reaction zone configuration is shown in
U. S. Patent No. 3,647,680 as a two-stage system having an
integrated regeneration facility which receives that catalyst
withdrawn from the bottom reaction zone. Similar stacked
configurations are illustrated in U. S. Patent No. 3,692,496
and U. S. Patent No. 3,725,249.
U. S. Patent No. 3,725,248 illustrates a mul,tiple-
stage system in side-by-side configurationwith gravity-flow-
ing catalyst particles being transported from the bottom oE
one reaction zone to the top oE the next succeeding reaction
zone, those catalyst particles being removed from the last
reaction zone being transferred to suitable regeneration
facilities.
General details of a three-reaction zone, stacked
system are presented in U. S. Patent No. 3,706,536 which
illustrates one type of multiple-stage system to which the
present inveAtive ~oncept is applicable. The particularly
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preferred construc-tion of the catalyst-retaining screen mem-
ber and perfora-ted centerpipe are shown -therein. These are
fabricated from a multiplicity of closely spaced, vertically-
disposed wedge-shaped wires, or bars. ~his produces a minimum
of friction and attrition as the catalyst particles move down-
wardly via gravity-flow. As generally practiced in a cata-
lyst reforming unit, each succeeding reaction zone contains
a greater volume of catalyst.
These illustrations are believed -to be fairly rep-
resentative of the art which has been developed in multiple-
stage conversion systems wherein catalyst particles are mov~
able through each reaction zone via gravity-flow. Note-
worthy is the fact that none recognize the existence of stag-
nant cataly.st areas which result when catalyst particles are
lodged against the perforated centerpipe by the lateral/radial
flow of vapor across the annular-form catalyst bed.
The reaction chamber encompassed by our inventive
. concept is suitable for use in hydrocarbon conversion systems
which are characterized as multiple-stage and in which cat-
alyst particles are movable via gravity-flow through each
reaction zone. Furthermore, the present invention is pri-
marily intended for utilization in reactor systems where the
: principal reactions are endothermic and effec~ed in vapor-
; phase. ~lthough the following discussion is specifically
directed toward catalytic reforming of naphtha boiling range
fractions, there isno intent to so limit the present inven-
tion. Catalytic reforming, as well as many ot~er processes,
has experienced several phases of development currently ter-
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minating in the system in which the catalyst beds assume
the -form of a descending column in one or more reaction ves-
sels. Typically, the catalysts are utilized in spherical
form, having a nominal diameter ranging from 0.~ to 4.0 mm;
this offers free-flow charac-teristics which are intended
neither to bridge, nor to block the descending column, or
-. columns, of catalyst within the overall reactor system.
: In one such multiple-stage system, the reaction
chambers are vertically stacked, and a plurality ~generally
from about 4 to about 16) of relatively small diameter con-
duits are employed to transfer catalyst particles from one
reaction zone to the next lower reaction zone (via gravity-
flow) and ultimately to withclraw catalyst par-ticles from
the last reaction zone. ~he catalyst particles are then
transported to the top of a catalyst regeneration facility,
also functioning with a descending column of catalyst par-
ticles; regenerated catalyst particles are then transported
to the top of the~upper reac-tion zone of the stack. In
order to facilitate and enhance gravity-flow within each
reaction vessel, as well as from one zone to another, it is
particularly important that the catalyst particles have a
relatively small nominal diame-ter, and one which is preferably
less than 4.0 mm. In a conversion system having the indi-
vidual reaction zones in side-by-side relationship, catalyst
transport vessels (of the type shown in U. S~ Patent No
3,839,1~7) are employed in transferring the catalyst parti-
cles from the bottom of one~zone to the top of the next suc-
. ceeding zone, and from the last reaction zone to the top of
the regeneration facility.
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Catalytic reforming o~ naphtha boiling range hy-
drocarbons, a vapor-phase operation, is effect~d at conver-
sion conditions which include catalyst bed temperatures in
the range of 371 to 5~9C. Other conditions generally in-
clude a pressure from ~.~ to 69 atmospheres~ a liquid hourl~
space velocity (defined as volumes of fresh charge stock per
hour, per volume of total catalys-t particles) of from 0.2
to 10.0 and a hydrogen to hydrocarbon mole ratio generally
- in the range of 0.5O1.0 to 10.0:1Ø Continuous regenerative
reforming systems offer numerous advantages when compared to
the prior art fixed-bed s~stems. Among these ls the capabil-
.ity of efficient operation at comparatively lower pressures
in the range of 4.4 to 14.6 atmospheres and higher consistent
inlet catalyst bed temperatures in -the range of 510 to 543C.
Ca-talytic reforming reactions include dehydrogenation
of naphthenes to aromatics, the dehydrocycliza-tion o~ paraf-
fins to aromati.cs, the hydrocracking of long-chain paraffins
into lower-boiling normally liquid material and the isomeri-
zation of paraffins. These reactions, the net resu:Lt of
which is endothermici-ty, are effected through the utilization
of one or more Group VIII noble meta].s (e.g. platinum, iridium,
rhodium, palladium} combined with a halogen (e.g~ chlorine
and/or fluorine) and a porous carrier material such as aluminae
Recent investigations have indicated that more advantageous
results are attainable through the cojoint use of a catalytic
modifier; these are generally selected Erom the group of
cobalt, nickel, gallium, germanium, tin, rhenium, vanadium
and mixtures thereof. Regardless of the particular selected
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catalytic composite, the ability to attain the advantage over
-the common fixed-bed systems is greatly dependent upon achiev-
ing acceptable catalyst flow down~-ard:ly through the system.
Ca-taly-tic reforming processes generally utilize
multiple stages, each of which contains a different quantity
of ca-talyst. The reactant stream, hydrogen and -the hydrocar-
bon feed, flow serially through the reaction zones in order
of increasing catalyst volume with interstage heating. In
a three-reaction zone system, typical catalyst loaciinys are:
.
Eirst, 10.0% to 30.0%; second, from 20.0~ to 40.0~, and
third, :Erom 40.0~ to 60.0%. W:ith respect to a ~our-react.ior
zone systern, suitable catalyst loading would be: first
5.0% to 15.0%; second, 15.0% to 25.0%; third, 25.0% to 35~0%;
and, fourth, 35.0% to 50.0%. Unequal catalyst distribution,
increasing in the serial direction of reactant stream flow,
facilitates and enhances the distribution of the reactions
as well as the overa].l heat of reaction.
The lodging of catalyst to the perforated center-
p:ipe stems primarily from the h:igh vapor velocity lclterially
across the annular-form catalyst-holding zone; this adverse
effect increases i.n degree as the cross-sectional area and
length of the catalyst bed decreases. In multiple-stage
catalytic reforming systems, therefore, the effect is most
pronounced in the first and second reaction zones, having
the smaller annular cross-sectional areas and lengths, some-
what less in the third reaction zone and of a relatively minor
consequence in the fourth reaction zone due to its length and
larger cross-sectional catalyst area.
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The catalyst-transfer, or withdrawal conduits of
the present invention afford a ready solution to the diffi-
culties attendant stagnant areas of catalyst particles re-
sulting from the lodging of ca~alyst particles to the sur-
face of the perforated cen-terpipe~ These conduits, used to
withdraw catalyst particles from an annular bed and transfer
them either into the annular bed of a succeeding reaction
zone, or into a withdrawal and transport vessel for intro-
duction into a regeneration tower/ are vertically-positioned
and circumferentially-disposed substantially adjacent the
ou~er surface (catalyst side) of the perforated centerpipe.
They extend substantially the entire len~th of the annular-
form catalyst bed, commencing just below the outlet ends of
those conduits used to introduce or transfer catalyst parti-
cles to the reaction chamber. Each conduit contains a first
plurality of apertures, or openings which face into the cat-
alyst bed and which are sized to permit catalyst particles
to flow therethrough. These catalyst access openings are
uniformly disposed al.ong the length of the conduit within
the catalyst bed to afford uniform transfer of the cata-
lyst particles~ Preferably, a second plurality of apertures,
di~posed substantially 180 opposite the catalyst access :
openings, face inwardly toward the perforated centerpipe,
and are sized to inhibit the flow of catalyst partlcles th re~
through. These smaller openings conduct reactant vapors,
which enter the conduits with catalyst particles, from the
conduits into the perforated centerpipe. More importantly,
these openings provide a flow path for the reactant stream
such that the catalyst particles within the conduits are
maintained in a hydrogen-enriched atmosphere.
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The catalyst transfer and withdrawal condui-ts
will generally number from about four to about sixteen.
, The precise number of catalyst-transfer conduits, as well
¦ as the number of catalyst access openings .disposea along
. 5 the length of each, is dependent upon the desi~n configu-
ration of each of the individual reaction zones in the en-
tire multiple-stage system. Principal factors are the
lengths and diameters of the reaction chamber, the outer
catalyst retaining screèn and the perforated centerpipe;
as above stated, the last two determine the quantity of
catalyst disposed in the reaction zone and espec.ially the
width of the annular-form bed. Other considerations in-
volve the desired quantity and qua:lity of the catalyti.cal-
ly reformed product, and the operating severity level
: lS needed to achieve these results. The latter determine
the catalyst regeneration rate which, in turn, dictates
the rate at which catalyst particles must be withdrawn
from the last reaction zone. A number of these consider-
ations will also dictate the quantity and size of the
smaller apertures which are disposed 1~0 opposite the
. catalyst access openings. In this r~gard, the limitation
on maximum size is determined by the nominal d.iameter of
the catalyst particles. In contrast to the situation
where substantial areas of stagnant catalyst exist, the
use of the described catalyst-transfer conduits produces
uniform catalyst withdrawal throughout the annular-form
bed.
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Particularly preferred catalyst-transfer con-
dui-ts contain a plurality of internal, inwardly-inclined
bafEles, each one of which extends downwardly to reduce
the cross-sec-tional area of the conduits above each of
the access openings therein. These baffles serve to di-
vert catalyst particles, flowing through the conduits,
away from the next lower catalyst access opening. These
inclined bafEles may terminate in the same horizontal
plane which contains thè lower periphery~of the catalyst
access openings, below the access openings, or above the
access openinys. Similarly, they may simultaneously ter-
minate in the vertical plane containing the axis of the
conduit, or in a vertical plane between the axis and the
centerpipe, or in a vertical plane between the axis and
the catalyst access openin~s.
From the lowermost terminus of each inclined
baffle, a vertical baffle extends to a point above the up-
permost periphery of the next succeeding catalyst access
opening. In a particularly preferred configuration, the
lower terminus of each succeeding lower inclined baffle
and the vertical bafEle extending downwardly therefrom
lies in a vertical plane which is a lesser distance from
the catalyst access openings than the vertical plane in
which -the preceding upper inclined baffle and its verti-
cal baffle lies. These catalyst-transfer, or withdrawal
conduits afford a more uniform distribution of lateral
catalyst particle flow and tend to equalize catalyst resi~
dence time within the chamber.
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In further describing the present invention, ref-
erence will be made to the accompanying drawing. It is under-
stood that the drawing is presented solely for the purposes
of illustration, and is not intended to be construed as limit-
ing upon the scope and spirit of our invention as defined by
the appended clairns.
FIGURE 1 includes a catalyst ~ntroduction chamber
1 in which catalyst-holding zone 3 serves as a preheat section
for the catalyst particles, prior to the introduction thereof
into the reaction zone system, via indirect contact with the
reactant stream charge. Therefore, catalytic reaction chamber
2 is the first reaction zone in the system which the reactant
stream contacts.the catalyst. Subsequentl.y reaction chambers
will generally be of the same configuration (minus, o course,
the catalyst introduction chamber), but not necessarily having
the same dimension.
Fresh and/or regenerated catalyst particles 4 are
introduced, via line 6 and inlet port 7 into hold;.ng zone 3.
I Vaporous reactants, hydrogen and naphtha boiling range hydro-
carbons are introduced, via conduit 8 and inlet port 9, into
the annular space 5 formed between the interior wall o~ cham-
ber 1 and holding zone 3. This indirect heat-exchange ser~es
to maintain the catalyst particles at an elevated tomperature
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until such time as they are introduced into the reaction
chamber .
When catalyst particles are withdrawn from the
lowermost, or last reaction zone in the system, and grav-
ity-flow of catalyst particles commences throughout the
system, particles will be wi.thdrawn from holding zone 3
by way of conduit 10. These will he uni~ormly distributed
through a plurality (generally from about four to about
sixteen) of catalyst inlet conduits 11 into ànnular-form
space 16. This annular-form catalyst bed is def.ined by
outer catalyst-retaining screen member 13 and a perforated
centerpipe 15. The reactant stream flows into and around
the outer annulus 14, while being preven-ted from directly
entering the catalyst bed by imperforate top plate 12.
From outer annulus 14, the reactant stream rlows laterally
and radially throuyh the re-taining screen 13, into and
through the annular bed 16 of catalyst particles 4 and into
perforated centerpipe 15. The reaction product effluent is
withdrawn through outlet port 22; since the illustra-ted re-
action chamber 2 is the firs-t zone in the multiple stage
system, the product effluent will be introduced `into an ex-
ternal interstage heater in which the temperature is increased
prior to the introduction thereof into the next succeeding
. reaction zone.
Catalyst par-ticles, which would otherwise become
lodged against perfora-ted centerpipe 15, as a result of the
high vapor velocities laterally across the catalyst bed, are
caused to flow into and through apertures 18 in catalyst-
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transfer conduits 17 (generally numbering from about four
to about sixteen). ~pertures 18 face in-to annular catalyst
bed 16, and are disposed subs-tantially along the entire
length of conduits 17. ~t least one such aperture is located
pro~imate to the bottom o~ the catalyst bed as defined by
imperforate horizontal plate member 21. As particles are
withdrawn from the last reaction zone in the series, for
transport to suitable regeneration faci.lities, downward flow
via grav.ity commences, and the catalyst particles flow out of
reaction chamber 2 through trans:Eer tubes 17. In the present
illustration, the external portions 23 of transfer conduits
17 will enter the uppermost portion of the next succeediny
reaction zone, thus being considered the catalyst inlet con-
duits thereto. The vertical distance between the outlet of
catalyst inlet conduits 11 an~ the upper end of transfer con-
duits 17 is determined by the angle of repose assumed by
catalyst particles 4; this distance is such that the open
upper terminus of conduits 17 is above the bed o~ catalyst.
Catalyst transfer conduits 17 contain a second plurality
of apertures 19 which are disposed substantially 180 oppo-
site the larger apertures 18. Whereas the latter ~re sized
to permit the catalyst particles to ~low therethrough, the
former are sized to inhibit catalyst particle ~low, but per-
mit the flow of reactant stream into perforated cen-terpipe
15, by way of openlngs 20. The catalyst particles within
the transfer conduits 17 are thereby maintained in a hydro-
gen-rich atmosphere.
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FIGURE 2 is an enlarged, partially sectioned plan
view taken substarltially alony the line 2-2 of FIGURE 1.
As shown, catalyst inlet conduits 11 are circumferentially
disposed above annular-form space 16 such that about one-
S half of the catalyst particles are inside the circular
: positioning thereof and one-half is outside. Although the
catalyst-transfer tubes 17 may be separated a finite dis-
tance away from centerpipe 15, it is preferred that they
be in contact therewith as shown. FIGURE 3 is a partially
sectioned plan view of a portion of the reaction chamber 2
enlarged to show the preferred configurations of outer cat~
alyst-retaining screen member 13 and perforated centerpipe
15, both of which are formed by vertical wedge-shaped parallel
wires 13' anA 15', respectively.
FIGURE ~ is a partially-sectioned side elevation
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of a portion of one of the catalyst transfer, or withdrawal
conduits 17, enlarged to clarify apertures, or cakalyst open
ings 18 and the relationship thereof to internal inclined
baffles 25. The inclined baffles extend downwardly and in-
wardly from the uppermost periphery 24 of openings lB; in
this view, the inclined baffles 25 terminate in the vertical
plane containing the axis of the cylindrical conduit and also
above the horizontal plane containing the lowermost per.iphexy
of aperture 18. A vertical baffle 26 extends downwardly from
: 25 the lower terminus of each of the inclined baffles 25 and
terminates above the uppermost periphery of the next succe~d-
ing lower catalyst opening lB. The smaller apertures 19 are
shown as being 180 opposite inclined baffles 25 as well as
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catalys-t access openings 18. FIGURE 5 iS a sectioned plan
view taken substantially along the line 5-5 of FIGURE 4.
This shows vertical baffle 26 which is the unnumbered line
in the plan views of FIGURES 2 and 3.
FIGURE 6 is another partially-sectioned side ele-
vation of one of the catalyst transfer conduits 17 presented
to illustrate another configuration of openings 18, i.nclined
. baffles 25 and vertical baffles 26. Here the inclined baffle
terminates in the vertical axis of the conduit and in the
horizontal plane containing the uppermost periphery of the
c~talyst access open.ing 18. The small apertures 19 which
face the perforated centerpipe are again shown as bein~ sub-
stantially 180 opposite the internal inclined baffles 2S.
FIGURE 7 is still another sectioned side elevation
of a catalyst transfer conduit 17, and shows the particularly
preferred configuration and relationship of catalyst access
openings 18, inclined bafEles 25 and vertical baffles 26.
~IGURE 8 is a plan view looking upwardly substantially along
the line 8-8 of FlGURE 7. Each succeeding lower inclined
baffle terminates in a vertical plane which is closer to the
vertical plane containing catalyst access openings 18 than
the vertical plane in which -the preceding upper inclined baffle
terminates. The same, as the Figure indicates, can he said
regarding vert.ical baffles 26, 26a, 26b, 26c and 26d. That
is, the distance between the vertical baffles and the vertical
plane containing catalyst access openings 18 decreases in
the direction of catalyst particle flow in a downwaxdly di
~ rection through the transfer conduit.
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