CA1104963A - Catalytic reaction chamber for gravity-flowing catalyst particles - Google Patents

Abstract

CATALYTIC REACTION CHAMBER FOR
GRAVITY-FLOWING CATALYST PARTICLES

ABSTRACT

A catalytic reaction chamber for contacting a re-actant stream with catalyst particles which are disposed as an annular-form bed and are downwardly movable therethrough via gravity-flow. The annular bed is spaced between a cat-alyst-retaining screen and a perforated centerpipe. A plu-rality of vertically-positioned catalyst transfer, or with-drawal conduits are circumferentially-disposed substantially adjacent the outer surface of the centerpipe and extend the entire length of the catalyst bed. These contain a first plurality of apertures which face into the bed of catalyst particles and which are sized to permit catalyst particles to flow therethrough. Preferably, a second plurality of apertures is disposed substantially 180° opposite the first plurality of apertures, and sized to inhibit the flow of catalyst particles therethrough. The latter serve to conduct reactant stream vapors out of the transfer conduits into the perforated centerpipe and insure a hydrogen atmosphere sur-rounding the catalyst particles flowing therethrough.

Description

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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 I .

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i3 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 ~4-; ' ' 6~

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-~ -5-. .
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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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Lg~i3 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 ~ : .
~ 7-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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. _g_ 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:
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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.

~3 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.

. . , 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-..

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 ..
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 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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Claims (11)

WE CLAIM AS OUR INVENTION:

1. A catalytic reaction chamber for effecting con-tact of a reactant stream with catalyst particles which are (1) disposed therein as an annular-form bed and, (2) downwardly movable therethrough via gravity-flow, said re-action chamber comprising, in cooperative relationship:
(a) an outer, perforated catalyst-retaining screen (i) concentrically-disposed within and, (ii) hav-ing a cross-sectional area less than said chamber to pro-vide a reactant stream manifold space therebetween;
(b) an inner, perforated centerpipe (i) concen-trically-disposed within and, (ii) having a cross-section-al area less than said catalyst-retaining screen to pro-vide said annular-form catalyst bed therebetween;
(c) a plurality of catalyst inlet conduits con-nected to the upper portion of said chamber and communi-cating with said annular-form catalyst bed; and, (d) a plurality of vertically-positioned cata-lyst-transfer, or withdrawal, conduits (i) circumferen-tially-disposed substantially adjacent the outer surface of said perforated centerpipe, (ii) extending substantial-ly the entire length of said annular-form catalyst bed and, (iii) containing a first plurality of apertures fac-ing into said catalyst bed and sized to permit catalyst particles to flow therethrough.

2. The catalytic reaction chamber of Claim 1 wherein said catalyst-transfer, or withdrawal, conduits contain a second plurality of apertures facing said perforated cen-terpipe and sized to inhibit the flow of catalyst particles therethrough.

3. The catalytic reaction chamber of Claim 1 wherein said catalyst-transfer, or withdrawal, conduits contain a plurality of internal, inclined baffles each one of which extends downwardly from the uppermost periphery of each of the apertures in said first plurality.

4. The catalytic reaction chamber of Claim 2 wherein the first and second pluralities of apertures in said catalyst-transfer, or withdrawal, conduits are disposed along the length thereof.

5. The catalytic reaction chamber of any of Claims 1 to 3 wherein said catalyst inlet conduits number from about four to about sixteen.

6. The catalytic reaction chamber of any of Claims 1 to 3 wherein said catalyst-transfer, or withdrawal, conduits number from about four to about sixteen.

7. The catalytic reaction chamber of Claim 3 wherein each of said inclined baffles terminates in the horizontal plane containing the lowermost periphery of the apertures in said first plurality, and in the vertical plane containing the axis of said conduits.

8. The catalytic reaction chamber of Claim 3 wherein each of said inclined baffles terminates in the vertical plane containing the axis of said conduits at a point above the lowermost periphery of each aperture in said first plurality.

9. The catalytic reaction chamber of Claim 3 wherein each succeeding lower inclined baffle terminates in a vertical plane a lesser distance from the vertical plane containing said first plurality of apertures than the vertical plane in which the preceding upper inclined baffle terminates.

10. The catalytic reaction chamber of any of Claims 7 to 9 wherein a vertical baffle extends from the lower terminus of each of said inclined baffles and terminates above the uppermost periphery of the next succeeding aperture in said first plurality.

11. The catalytic reaction chamber of Claims 2 or 4 wherein the apertures in the second plurality are substantially 180° opposite the surface of each of said inclined baffles.