CA1100899A - Multiple-stage hydrocarbon conversion with gravity- flowing catalyst particles - Google Patents

Multiple-stage hydrocarbon conversion with gravity- flowing catalyst particles

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Publication number
CA1100899A
CA1100899A CA302,841A CA302841A CA1100899A CA 1100899 A CA1100899 A CA 1100899A CA 302841 A CA302841 A CA 302841A CA 1100899 A CA1100899 A CA 1100899A
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Canada
Prior art keywords
reaction zone
flow
reaction
effluent
catalyst
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA302,841A
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French (fr)
Inventor
Elliot Veinerman
Kenneth D. Peters
Donald E. Felch
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Honeywell UOP LLC
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UOP LLC
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Filing date
Publication date
Priority claimed from US05/795,250 external-priority patent/US4119526A/en
Priority claimed from US05/795,054 external-priority patent/US4119527A/en
Application filed by UOP LLC filed Critical UOP LLC
Application granted granted Critical
Publication of CA1100899A publication Critical patent/CA1100899A/en
Expired legal-status Critical Current

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/08Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
    • B01J8/12Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles moved by gravity in a downward flow
    • B01J8/125Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles moved by gravity in a downward flow with multiple sections one above the other separated by distribution aids, e.g. reaction and regeneration sections
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G35/00Reforming naphtha
    • C10G35/04Catalytic reforming
    • C10G35/10Catalytic reforming with moving catalysts
    • C10G35/12Catalytic reforming with moving catalysts according to the "moving-bed" method

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)

Abstract

* * ABSTRACT * *
MULTIPLE-STAGE HYDROCARBON CONVERSION
WITH GRAVITY-FLOWING CATALYST PARTICLES

A multiple-stage catalytic conversion system in which a hydrocarbonaceous charge stock and hydrogen flow serially through a plurality of catalytic reaction zones in each of which the catalyst particles are movable via gravity-flow. The flow of the product effluent from at least one reaction zone is restricted. This technique in-creases the pressure drop within the entire reactor cir-cuit, and serves to alleviate the problems associated with the occurrence of stagnant catalyst areas within the reaction zone which are unable to assume a downward gravity-flow pattern. Flow restriction may be effected either be-fore, or after the inter-reaction zone heaters, preferably before.

Description

MULTIPLE~STAGE HYDROCARBO~ CONVERSIO~
WITH G~VITY-FLOWI~G CA~ALYST PARTICLES

SPECIFICATION

The present invention is directed toward an im-proved technique for effecting the catalytic conversion of a hydrocarbonaceous reactant stream in a multiple-stage reaction system wherein (i) the reactant stream flows serially through the plurality of reaction zones and, (ii) the catalyst particles are movable through each reaction zone via gravity-flow. More particularly, the described process technique is adaptable for utilization in vapor-phase systems wherein the conversion reaçtions are principally endothermic, and where the flow of the hy-drocarbonaceous reactant stream, with respect to the down-ward direction of catalyst particle movement, is cocurrent and essentially radial.
Various types of multiple-stage reaction systems have found widespread utilization throughout the petroleum and petrochemical industries for effecting multitudinous reactions, especially hydrocarbon conversion reactions.
Such reactions are either exothermic, or endothermic, and encompass both hydrogen-producing and hydrogen-consuming processes. Multiple-stage reaction systems generally take one of two forms: (1) side-by-side configuration with intermediate heating between the reaction zones, and 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 ~l~Ut~9 multiple catalytic contact stages. Such reactor systems, as applied to petroleum refining, have been employed to effect numerous hydrocarbon conversion reactions includ-ing those which are prevalent in catalytic reforming, al-kylation, ethylbenzene dehydrogenation to produce styrene, and other dehyarogenation processes. My invention is specifically intended for utilization in those processes where the conversion reactions are effected in vapor-phase, catalyst particles are movable via gravity-flow, 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 stack.
Since catalyst particles which are movable through a reaction system by way of gravity-fl~w are nec-essarily moving in a downwardly direction, the present technique contemplates the withdrawal of catalyst parti-cles from a bottom portion of one reaction zone and the introduction of fresh, or regenerated catalyst particles into the top portion ofa second reaction zone. The pres-ent technique is also intended to be applied to those re-action systems wherein the catalyst is disposed as an an-nular bed and the flow of the reactant stream, serially from one zone to another reaction zone, is perpendicular, or radial to the movement of catalyst particles. In the interest of brevity, the following discussion will be di-rected toward those systems wherein a downwardly moving bed of catalyst particles is employed in the conversion of a hydrocarbonaceous reactant stream, with the catalyst particles being disposed in the form of an annular bed, through which the reactant stream flows laterally and ra-dially.
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 re-action chamber containing a coaxially disposed catalyst-retaining screen, having a nominal, internal cross-sec-tional area less than said chamber, and a perfora~ed cen-terpipe having a nominal, internal cross-sectional area which is less than the catalyst-retaining screen. The re-actant stream is introduced, in vapor-phase, into the an-nular-form space created between the insid-e wall of the chamber and the outside surface of a catalyst-retaining screen. The latter forms an annular-form, catalyst-hold-ing zone with the outside surface of the perfora~ed cen-terpipe; vaporous reactant flows laterally and raaially through the screen and catalyst zone into the centerpipe and out of the reaction chamber. Although the tu~ular-form configuration of the various reactant components may take any suitable shape -- e.g., triangular, square, ob-long, diamond, etc. -- many design, fabrication and tech-nical considerations dictate the advantages ofusing com-ponents which are substantially circular in cross-section.
A multiple-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-flowing catalyst particles, from one reaction zone to another, as well as introduction of fresh catalyst par-ticles and withdrawal of used catalyst particles, is effected through the utilization of a plurality of cata-lyst-transfer 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 the high vapor flow through the annular-form catalyst-holding sections results in catalyst particles being unable to move in the vicinity of the perforated centerpipe, there-by creating stagnant catalyst areas where the catalyst particles are prevented from assuming the gravity-flow pattern.
Accordingly, the present invention comprises in a multiple-stage catalytic conversion system, wherein ~1) heated hydrocarbonaceous charge stock and hydrogen flow serially through a plurality of catalytic reaction zones;
(2) the reaction product effluent from each zone is heated prior to the introduction thereof into the next succeeding reactiOn zonei and, (3) catalyst particles are movable through each reaction zone via gravity-flow, the method of effecting the conversion of said charge stock which com-prises the steps of: (a) heating said charge stock and hydrogen, and introducing the heated mixture into a first reaction zone maintained at hydrocarbon conversion condi-tions; (b) heating the resulting first reaction zone efflu-ent and introducing the heated effluent into a succeeding reaction zone maintained at hydrocarbo~ conversion conditions;
(c) restricting the flow of the effluent from at least one reaction zone in said plurality and separating the ef-fluent from the last reaction zone to provide (i) a nor-mally liquid product stream, and (ii) a hydrogen-rich vaporous phase; (d) at least periodically withdrawing catalyst particles from the last of said reaction zones;
and, (e) at least periodically introducing fresh, or regen-erated catalyst particles into the first of said reaction zones.
In a preferred embodiment, the invention is further characterized in that the flow of product effluent from an intermediate reaction zone is restricted prior to the introduction thereof into the next succeeding reaction zone, and the 10w of the effluent from the last reaction zone is restricted prior to effecting the separation thereaf.
In a more preferred embodiment, the invention is further characterized in that a portion of the hydrogen-rich vaporous phase is also restricted and recycled back to the first reaction zone.
Various types of hydrocarbon conversion processes ùtilize multiple-stage reactor systems, either in a side-by-side configuration, as a vertically-disposed stack, or a combination of a stacked system in side-by-side relation with one or more separate reaction zones.
Such systems may be employed in a wide variety of hydrocarbon conversion reactions. While my inventive concept is adaptable to many conversion reactions and pro-cesses, through the reactor system of which the catalyst particles are movable via gravity-flow, it will be further described in conjunction with the well known endo~hermic catalytic reforming process.
Historically, catalytic reforming was effected in a non-regenerative, fixed-bed system comprising a plur-ality of reaction zones disposed in side-by-side relation.
When the catalytic composite had become deactivated to the extent that continuous operation was no longer econom-ically feasible, the entire unit was shut-down and the catalyst regenerated in situ. Of a more recent vintage was the so-called "swing bed" system in which an extra re-actor was substituted for one which was due to be placed off-stream for regeneration purposes. Still more recent-ly, multiple-stage reactor systems 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-contain-ing zone to another, and ultimately transfer to a suit-able regeneration system also preferably functioning with a downwardly-moving bed of catalyst particles. In effect, the catalyst particles are maintained from one section to another in a manner such that the flow of catalyst parti-cles is continuous, at frequent intervals, or at extended intervals, with the movement being controlled by the quan-tity of catalyst withdrawn from the last of the series of individual reaction zones.
U.S. Patent No. 3,470,090 illustrates a multiple-stage, side-by-side reaction system with intermediate heating of the reactant stream which flows serially through the indi-vidual reaction zones. Catalyst particles withdrawn from g9 any one of the reaction zones are transported to suitable regeneratlon f~cilities. This type of system can be modi-fied to the ex-tent that the catalyst particles withdrawn from a given reaction zone are transported to the next succeeding reaction zone, while the catalyst withdrawn from the last reaction zone may be transported to a suit-able regeneration facility. The necessary modifications can be made in the manner disclosed in U.S. Patent No.
3,839,197, involving 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 illustra-ted 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. Paten~ No.
3,692,496, and U.S. Patent No. 3,725,249.
U.S. Patent No. 3,725,248 illustrates a multiple-~
stage system in side-by-side configuration with gravity-flowing catalyst particles being transported from the bottom of one reaction zone to the top of the next suc-ceeding 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 and illustrates one type of multiple-stage system to which ~l~UB99 the present inventive concept is applicable. As gen-erally practiced in a catalyst reforming unit, each succeeding reaction zone contains a greater volume of catalyst in that the annular-form catalyst-holding zone is greater in cross-sectional area.
These illustrations are believed to be fairly representative of the art which has been developed in mul-tiple-stage conversion systems wherein catalyst particles are movable through each reaction zone via gravity-flow.
Noteworthy is the fact that none recognize the existence of stagnant catalyst areas which result when catalyst par-ticles are lodged against the perforated centerpipe by the lateral/radial vapor flow across the annular form catalyst bed. Likewise, it is readily ascertained that there is no recoqnition of restricting the reaction zone effluent to alleviate these difficulties and remedy the problem.
The process encompassed by my inventive concept is suitable for use in hydrocarbon conversion systems which are characterized as multiple-stage and in which catalyst ` particles are movable via gravity-flow through each reaction zone. The present invention is principally intended for utilization in reactor systems where the principal reacticns are endothermic and are effected in vapor-phase. Although~
¦ the following discussion is specifically directed towara catalytic reforming of naphtha boiling range fractions, ¦ there is no intent to so limit the present invention.
Catalytic reforming, as well as many other processes, has I experienced several phases of development currently ter-minating in the system in which the catalyst beds assume _g_ the form of a descendiny column in one or more reaction vessels~ Typically, the catalysts are utilized in spheri-cal form having a nominal diameter ranging from 0.8 to 4.0 mm. in order to offer free-flow characteristics which will neither bridge, nor 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 (general-ly from about 6 to about 16) of relatively small diameter conduits are employed to transfer catalyst particles from one reaction zone to the next lower reaction zone (via gravity-flow) and ultimately to withdraw catalyst parti-cles from the last reaction zone. The catalyst particles are then transported to the top of a catalyst regeneration facility, also functioning with a descending column of catalyst particles; regenerated catalyst particles are then transported to the top of the upper reaction zone of the stack. In order to facilitate and enhance gravity-flow within each reaction vessel, as welI as from one zone to another, it is particularly important that the catàlyst particles have a relatively small nominal diameter, and one which is preferably less than 4.0 mm. In a conversion system having the individual reaction zones in side-by-side relationship, catalyst transport vessels (of the type shown in U.S. Patent No. 3,839,197) are employed in transferring the catalyst particles from the bottom of one zone to the top of the succeeding zone, and from the last reaction zone to the top of the regeneration facility.

Catalytic reforming of naphtha boiling range hydro-carbons, a vapor-phase operation, is effected at conversion conditions which include catalyst bed temperatures in the range of 371 to 549C. Other conditions generally include a pressure from 4.4 to 69 atmospheres, a liquid hourly space velocity (defined as volumes of fresh charge stock per hour, per volume of total catalyst particles) of from 0.2 to 10.0 and a hydrogen to hydrocarbon mole ratio generally in the range of 1.0:1.0 to 10.0:1Ø Continuous regenerative reforming systems offer numerous advantages when compared to the prior art fixed-bed systems. Among these is the capability 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.
Catalytic reforming reactions include dehydrogenation of naphthenes to aromatics, the dehydrocyclization of paraffins to aromatics, the hydrocracking of long-chain paraffins into lower-boiling normally-liquid material and the isomerization of paraffins. The reactions, the net result of which is endothèrmicity, are effected through the utilization of one or more Group VIII noble metals (e.g. platinum, iridium, rhodium, palladium) combined with a halogen (e.g. chlorine and/or fluorine) and a porous carrier material such as alumina. Recent investigations have indicated that more advantageous results are attainable through the cojoint-use of a catalytic modifier; these are generally ; 1 /~,~ - 1 1 -selected from the group of cobalt, nickel, gallium, germani~, tin, rhenium, vanadium and mixtures thereof.
Regardless oi the particular selected catalytic composite, the ability -to attain the advantage over the common fixed-bed systems is greatly dependent upon achieving acceptable catalyst flow downwardly through the system.
Catalytic reforming processes generally utilize multiple stages, each of which contains a ~ifferent quantity of catalyst, generally expressed as volume percent. The reactant stream, hydrogen and the hydrocar~on feed, flow serially through the reaction zones in order of increasing catalyst volume with interstage heating. In a three-reaction zone system, typical catalyst loadings are: first, 10.0%
to 30.0%; second, from 20.0% to 40.0%; and, third, from 40.0~ to 60.0%. With respect to a four-reaction zone system, 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 overall heat of reaction.
~he lodging of catalyst to the perforated center-pipe stems primarily from the high vapor velocity laterally across the annular-form catalyst-holding zone, this adverse effect increasing in degree as the cross-sectional area and length of the catalyst bed decreases. In multiple-stage catalytic reforming systems, therefore, t~e effect is most pronounced in the first and second reaction zones, having the smaller annular cross-sectional areas, somewha~ less in the third reaction zone and of a relatively minor consequence in the fourth reactior. zone due to its length and larger cross-sectional catalyst area. Restricting the flow of the product effluent from the last reaction zone in the serial plurality; will reduce the amount of lodged catalyst.
Preferably, the flow of the product effluent from all the reaction zones is restricted prior to the introduction there-of into the next succeeding reaction zone, or with respect to the last reaction zone, prior to the separation thereof into a normally li~uid product and a hydrogen-rich vapor-ous phase. In a four-zone system, with respect to the in-termediate reaction zones, being numbers 2 and 3 in a four-zone system, it is preferred to restrict the flow of ef--fluent therefrom in addition to that emanating from the fourth reaction zone, with or without restriction of the first zone effluent.
The flow restrictions of the various reaction zone effluents may be effected in any suitable manner which produces, or results in an additional pressure drop increase. for the overall reactor system, of from .07 to 0.7 atmospheres for each such restriction. Restriction of effluent flow may be accomplished through the use of venturi tu~es, orifice plates, etc.; the orifice plate is preferred for the vapor-phase operation.
~rincipally, the lodging of catalyst to the per-forated centerpipe is a function of two dependent variables:
(1) the vapor mass flow rate; and, (2) the density of the .

ll~U~ 9 vapors flowing laterally through the annular-form catalyst bed. To reduce~ or eliminate the lodyed catalyst, for a given design flow of charge stock, the rate of hydrogen-rich gas recycle to the system must be reduced. This, how-ever, reduces the total mass flow to a given reaction zone, which, in turn, reduces the reactor system pressure drop.
Of course, the effective pressure in the initial reaction zone, in which catalyst pinning is most prevalent and troublesome, is reduced, a corresponding reduction in vapor density ensues. The utilization of restriction orifices (or other suitable devices) between reaction zones increases the pressure drop in the reactor circuit; this increases the pressure in the first reaction zone and thus the density of the vapors. Higher vapor density alleviates the catalyst lodging problems which results in stagnant catalyst areas.
The use of restriction orifices also affords greater recycle gas flow which reduces carbonaceous material deposition and the regeneration load imposed upon the regeneration facility.
Furthermore, the final reaction zone functions at a lower pressure which gives rise to a liquid yield advantage. Pre-ferably, the restriction orifices are placed upstream of the reaction zone inter-heaters to decrease the heater operating pressure and increase the velocity of the reactor effluent in the heater tubes~ In accordance with a more preferred mode of effecting the present invention, the recycle hydrogen flow is also restricted. While the restriction of the recycled hydrogen flow does not contribute to the alleviation of stagnant catalyst areas to as great an extent as the rcstrictions of reaction zone effluent, it does serve to insure better flow distribution of the reactant stream to the combined feed-heat exchanger, particularly when the heat exchanger consists of at least two heat exchangers in parallel.
In further describing the present invention, and its method of operation, reference will be made to the accompanying drawing~ It is understood that the draw-ing is presented solely for the purposes of illustration, and the same is not intended to be construed as limiting upon the scope and spirit of our invention as defined by the appended claims. Therefore, miscellaneous appurtenan-ces, not required for a complete understanding of the in-ventive concept, have been eliminated or reduced in num-ber. Such items are well within the purview of one pos-sessing the requisite skill in the appropriate art. The illustrated embodiment is presented as a simplified sche-matic flow diagram showing four reaction zones, stacked catalytic reforming system 1 havinq an upper first reac-tion zone I, two intermediate zones II and III, and a low-ermost fourth reaction zone IV.
The drawing illustrates the particularly pre-ferred embodiment in which the product effluent from each of the reaction zones is restricted, in addition to the restriction of the flow of hydrogen-rich recycle gas.
With respect to the four reaction zones I, II, III and IV, this is accomplished through the use of restriction orifices 10~ 14, 18 and 22, respectively. The flow of the hydrogen-rich recycle gas is restricted through the utilization of restriction orifice 3 Stacked, gravity-flowing catalytic reaction sys-tem 8 is shown as having four individual reaction zones which are sized as to length and annular catalyst cross-sectional area such that the distribution of the total catalyst volume is 10.0~ (zone I), 15.0~ (zone II), 25.0~
(zone III~ and 50.0~ (zone IV). In a normal, substantial-ly problem-free operation, fresh or regenerated catalyst particles are introduced through conduit 29 and inlet port 30 into the uppermost zone I and flow via gravity therefrom into reaction zone Il, from zone II into zone III, from zone III into zone IV, and are ultimately with-drawn from the reactor system through a plurality of out-let ports 31 and conduits 32. Catalyst particles so re-moved may be transported to a continuous regeneration zone (not illustrated), or may be stored until a suffici-ent quantity is available for a batch-wise regeneration.
The rate of catalyst flow through stacked reactor system 8, or the period of time required for catalyst particles~
to be introduced into the system, traverse the four reac-tion zones and be withdrawn for regeneration, is deter-mined by the rate at which the latter is effected. By monitoring various operating parameters while the system is in continuous operation, the catalyst withdrawal rate, or regeneration load can be controlled.
The naphtha boiling range charge stock is intro-duced into the process by way of line l, admixed with a hydrogen-rich vaporous phase from line 2, containing 2 restriction orifice 3 having a rating of about 0.41 atm., and introduced into heat-exchanger ~s. The temperature of the mixture is increased by way of indirect heat-exchange with hot product effluent entering by way of line 21.
The thus-heated mixture continues through conduit 5 into charge heater 6, and therefrom through line 7 into upper-most reaction zone I at a temperature required to provide the desired temperature at the inlet to the first cata-lyst bed disposed therein.
~eaction product effluent from catalyst zone I
passes through line 9, containing restriction orifice 10 rated at about 0.34 atm., into inter-heater 11, and there-from through line 12 into first intermediate reaction zone II. Product effluent from catalyst zone II is with-drawn by way of line 13, containing a restriction orifice 14 rated at about 0.41 atm., and is introduced thereby in-to inter-heater 15; the heated vaporous material is intro-duced into second intermediate reaction zone III b~ way of conduit 16. Conduit 17, containing a restrictlon ori-fice 18, also rated at 0.41 atm., carries the effluent from catalytic zone III into-interheater 19, the heated mixture being introduced into lowermost reaction zone IV
by way of line 20~
The reaction product effluent from lowermost catalytic zone IV is withdrawn by way of line 21, contain-ing restriction orifice 22 having a rating of about 7.0 psi. The product effluent continues through conduit 21 and is utilized as the heat-exch2nge medium in heat-ex-changer 4. Thus cooled, the product effluent passes through line 23 into condenser 24 wherein cooling and condensation takes place at a temperature in the range of about 16C to about 60C, and the mixture passes through line 25 into separation zone 26. Hydrogen-rich vaporous material is withdrawn through conduit 2, containing restriction orifice 3, for recycle at least in part to uppermost reaction zone I; excess hydrogen is withdrawn from the process through line 28, the rate being determined by suitable pressure control. The normally liquid product effluent is withdrawn by way of line 27 and introduced thereby into suitable fractionation facilities (not illustrated).
Although indicated as a single separation vessel 26 and condenser 24, the separation of the product effluent in line 25 may be effected using an initial low pressure separator followed by a high pressure separator. Vaporous material from the low pressure separator is compressed and introduced into a high pressure cooler in admixutre with the liquid material recovered from the low pressure separator.
The mixture is then introduced into the high pressure separator from which the hydrogen-rich recycle vaporous phase and a normally liquid product effluent are recovered.

jl ~ -18-

Claims (15)

I CLAIM AS MY INVENTION:
1. In a multiple-stage catalytic conversion sys-tem, wherein (1) heated hydrocarbonaceous charge stock and hydrogen flow serially through a plurality of catalytic re-action zones; (2) the reaction product effluent from each zone is heated prior to the introduction thereof into the next succeeding reaction zone; and, (3) catalyst particles are movable through each reaction zone via gravity-flow, the method of effecting the conversion of said charge stock which comprises the steps of:
(a) heating said charge stock and hydrogen, and in-troducing the heated mixture into a first reaction zone main-tained at hydrocarbon conversion conditions;
(b) heating the resulting first reaction zone ef-fluent and introducing the heated effluent into a succeeding reaction zone maintained at hydrocarbon conversion conditions;
(c) restricting the flow of the effluent from at least one reaction zone in said plurality and separating the effluent from the last reaction zone to provide (i) a normal-ly liquid product stream and, (ii) a hydrogen-rich vaporous phase;
(d) at least periodically withdrawing catalyst par-ticles from the last of said reaction zones; and, (e) at least periodically introducing fresh, or regenerated catalyst particles into the first of said re-action zones.
2. The method of Claim 1 wherein the flow of prod-uct effluent from the last reaction zone is restricted prior to effecting the separation thereof.
3. The method of Claim 1 wherein the flow of product effluent from an intermediate reaction zone is restricted prior to the introduction thereof into the next succeeding reaction zone, and the flow of the effluent from the last reaction zone is restricted prior to effecting the separation thereof.
4. The method of any of Claims 1 to 3 wherein the flow of at least a portion of said hydrogen-rich vaporous phase is restricted and recycled to said first reaction zone.
5. The method of any of Claims 1 to 3 wherein the reaction zones in said plurality are disposed in side-by-side relationship and catalyst particles are transferred from the bottom of one reaction zone to the top of the next succeeding reaction zone.
6. The method of any of Claims 1 to 3 wherein the reaction zones in said plurality are stacked and share a common vertical axis, and catalyst particles flow via gravity from one reaction zone to the next lower reaction zone in said stack.
7. The method of Claim 1 wherein said plurality contains at least three catalytic reaction zones.
8. The method of Claim 7 wherein the product effluent flow from each of said three reaction zones is restricted.
9. The method of Claim 1 wherein said plurality contains four catalytic reaction zones.
10. The method of Claim 9 wherein the flow of the effluent from each of only the last three reaction zones is restricted.
11. The method of Claim 9 wherein the product ?ffluent flow from each of the four reaction zones is restricted.
12. The method of Claim 2 wherein the restriction of the flow of the effluent from the last reaction zone produces an additional reactor system pressure drop of from about 1.0 to about 10.0 psi.
13. The method of Claim 10 wherein each restriction of the flow of effluent from said last three reaction zones produces an additional reactor system pressure drop in the range of about 1.0 psi to about 10.0 psi.
14. The method of any of Claims 1 to 3 wherein the flow of at least a portion of said hydrogen-rich vaporous phase is restricted and recycled to said first reaction zone, and wherein the restriction of the flow of the recycled portion of said hydrogen-rich vaporous phase produces an additional pressure drop of from 1.0 psi to about 10.0 psi.
15. The method of any of Claims 1 to 3 wherein said catalytic conversion system comprises a multiple-stage hydrocarbon catalytic reforming process.
CA302,841A 1977-05-09 1978-05-08 Multiple-stage hydrocarbon conversion with gravity- flowing catalyst particles Expired CA1100899A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US795,250 1977-05-09
US795,054 1977-05-09
US05/795,250 US4119526A (en) 1977-05-09 1977-05-09 Multiple-stage hydrocarbon conversion with gravity-flowing catalyst particles
US05/795,054 US4119527A (en) 1977-05-09 1977-05-09 Multiple-stage hydrocarbon conversion with gravity-flowing catalyst particles

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CA1100899A true CA1100899A (en) 1981-05-12

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