US2686710A - Catalytic conversion of hydrocarbons - Google Patents

Description

Aug. 17, 1954 J. w. JEWELL CATALYTIC CONVERSION oF HYDRocARBoNs Filed June l, 1951 INVENTOR. JOSEPH W. JEWELL ayfaffpemf ATTORNEYS Patented Aug. 17, 1954 CATALYTIC CONVERSION OF f HYDROCARBONS Joseph W. Jewell, Summit, N. J., assigner to The M. W. Kellogg Company, Jersey City, N. J., a corporation of Delaware Original application July 7, 1945, Serial No.

603,668. Divided and this application .lune 1, 1951, Serial No. 229,458

1 This application is a division of copending application Serial No. 603,668, iiled July 7, 1945` now abandoned. Serial No. 603,668 was a continuation-in-part of application Serial No. 405,614, filed August 6, 1941 now U. S. Patent 2,385,446. The claims of the present application are directed to specific features disclosed but not claimed in said parent applications.

The present invention relates to improvements and practiced in relatively inexpensive equipment.

` Various other objects, advantages and features ci the invention will be apparent from the following detailed description thereof given in connection with the appended drawing wherein the gure is a diagrammatic illustration of a suitable arrangement of apparatus and process flow for the prac* tice of the invention as applied to the catalytic conversion of high boiling hydrocarbons such as in process and apparatus for effecting catalytic lo petroleum gas oil, or the like, to low boiling hydroconversions. In its specic aspects, the invencarbons. tion is directed particularly to an improved con- The principal units of the apparatus illustrated tinuous process of converting hydrocarbons by are: a heater l for supplying vaporized hydrotreatment over catalytic materials which become carbons at a temperature suitable for conversion, spent or deactivated during the conversion by l5 a reactor or conversion chamber 2 wherein partithe accumulation of carbonaceous material therecles of catalytic cracking material are contacted on, and which accordingly reduire periodic re- With the feed vapors undergoing cracking, a regeneration treatment to fit them for reuse in the generation vessel or regenerator 3 wherein the conversion step. The catalytic conversion of high particles of used or spent catalytic material are boiling hydrocarbons such as petroleum gas oil contacted with an oxygen-containing gas under and the like into low boiling hydrocarbons within conditions adapted to cause combustion of the the gasoline boiling range is an example of the carbonaceous deposit thereon, a blower Il or other latter type of conversion reaction of outstanding suitable means for supplying an oxygen-containimportance, ing gas, such as air, to the regenerator, and gas- It has been proposed, heretofore, to catalytisolid separating means 5 and t associated respeccally convert high` boiling hydrocarbons such as tively with the reactor and regenerator for sepagas oil to low boiling hydrocarbons Within the rating suspended particles from the effluent gases gasoline boiling range by passing vapors of the derived therefrom. high boiling hydrocarbons under suitable reac- Pursuant to the present invention, a relatively tion conditions in contact with a stationary bed dense concentrated phase or mass of `catalytic of a cracking catalyst disposed in a catalyst particles is formed in the conversion zone or rechamber. Pursuant to such processes, after the generation zone, or preferably both, and moved activity of the catalyst is decreased by reason of laterally in contact with the vaporous or gaseous the formation of a carbonaceous deposit thereon component which travels upwardly through the to an extent where regeneration is necessary or laterally moving Catalyst at a relatively low Vedesirable, the activity of the catalyst is restored locity, The conversion zone and regeneration by stopping the flow oi oil vapor tothe chamber Zone preferably are constituted by horizontally and passing an oxygen-containing gas `into the elongated vessels of relatively great length comchamber in contact with the spent catalyst, therepared to their width and depth, or diameter in by regenerating it in situ by combustion of the the case of cylindrical vessels. Catalytic particles carbonaceous deposit. Although such processes undergoing contact with the vaporous or gaseous are commercially practicable they are subject to component are supplied at one end portion of the a number of inherent limitations and disadvan elongated vessel and withdrawn at the opposite tages which are eliminated by the present inend portion. In the case of the conversion zone, vention. Among these are the intermittent the rate of addition of the fresh or regenerated nature of the" operation, variations in product catalyst particles thereto and the corresponding quality and quantity during the reaction period rate of withdrawal is such as to maintain the and difficulty in temperature control, particularly laterally moving dense mass at the desired average in the regeneration operation. degree or level of catalytic activity. In the case A primary object of my invention is the proof the regeneration zone, used or spent catalytic vision of a continuous process of eiecting the particles are added thereto and withdrawn at catalytic conversion of hydrocarbons and analosuch a rate that the catalytic particles will regous reactions, wherein the mentioned disadvanmain in this zone for the period of time required tages of the intermittent type of operation are to eliminate or reduce the carbonaceous deposit obviated, and which may readily be controlled tothe desired extent. The vaporous or gaseous component is supplied at such a rate that its upward velocity through thee onversion and regeneration zone is adapted to maintain the mass of catalyst particles therein in a readily fiowable but relatively dense state. This condition of the mass of catalyst particles is such that it resembles a liquid in its flow characteristics and the aerated mass of catalyst in the intermediate portion of the zone is accordingly displaced and caused to flow laterally by the addition of catalytic particles at one end of the zone and withdrawal of corresponding amounts at the opposite end of the zone.

Following now the typical process ow illustrated by the drawing, the feed to the process for example a petroleum gas oil, or a similar high boiling hydrocarbon fraction, is introduced through line 2 to heating coil 3' in furnace I wherein it is vaporized and heated to a temperature suitable for the subsequent conversion operation. From furnace I the feed vapors are passed by transfer line 4 to a suitable vapor distributing means such as manifold 5. From manifold 5' a plurality of branch valved feed lines 6' connect with the lower portion of reactor 2. The quantity of feed vapors introduced through each of the branch lines may be suitably independently regulated by the individual valves 8. Lines 6 and lines 2l preferably terminate in suitable distributing means such as a perforated spider or porous plates (not shown) to provide substantial uniform horizontal distribution of the vapor throughout the conversion zone.

Particles of a suitable catalytic cracking material, for example an activated clay such as Super-Filtrol in finely divided or powdered condition is supplied at one end portion of reactor 2 through the catalyst inlet conduit 1. Reactor 2, as shown, consists of a cylindrical vessel of relatively great length, or elongated horizontally relative to its diameter. Fresh catalyst may be supplied through inlet l, but in normal operation this catalyst will consist largely of previously regenerated hot catalyst withdrawn from regenerator 3 through line 9. From line 9 the regenerated catalyst is picked up by a stream of a suitable conveying fluid such as steam injected through line II and conveyed through transfer line I0 to the catalyst inlet 'I. The quantity of the conveying uid employed and the relative cross-sectional area of the transfer line IB compared to the corresponding area of reactor 2 are such that the catalyst particles drop out of the stream of conveying fluid into the reactor. This separation may be facilitated by a baiTle I2 disposed across the path of the flowing mixture of conveying fluid and catalyst particles introduced through inlet 1.

Vapors of the hydrocarbons undergoing treatment are admitted through lines 6 at the base of reactor 2 in .such quantity that the mass of catalyst particles, the upper level of which is indicated by dotted line I3, is maintained in a readily flowable but relatively concentrated or dense condition.r In this state the mass of particles assumes a condition resembling that of a liquid in its ow characteristics, and is caused to flow or be positively displaced laterally through the reactor by the addition of active or regenerated catalyst at one end portion of the reaction zone through inlet 'I and the withdrawal of used or spent catalyst from the opposite end portion of the reaction zone through the loWer catalyst outlet I4 which communicates directly with the dense catalyst phase. The height of the upper level I3 of the dense catalyst phase is dependent upon the total quantity of catalyst in the system and the rate at which catalyst is withdrawn through the lower catalyst outlet III, which rate is controlled by valve I5. Accordingly, level I3 may be maintained at any desired height by suitable control of the rate of withdrawal of catalyst through valve I5 and regulation of the total amount of catalyst contained in the system. The latter regulation may be accomplished by either adding catalyst from make up catalyst hopper I6 to the system or by withdrawing a quantity of circulated catalyst to storage as required. The level I3 is preferably maintained a substantial distance below vapor outlets Il, most suitably in the lower half of the reactor as indicated, in order to provide an ample catalyst-vapor disengaging space in the reaction zone above the dense catalyst phase. Under such conditions a relatively small portion of the circulated catalyst is carried out of the reaction zone by the vaporous reaction products withdrawn overhead from the reactor through outlet lines Il'. Other conditions being fixed, the quantity of solid particles carried out with the vapors through lines I'I is dependent upon the height of level I3. For example, if valve I5 was completely closed level I3 would rise to an extreme limit where solid particles would be carried out through vapor lines II at the same rate as added through inlet l. Conversely, by progressively increasing the 'distance between the vapor outlet and the level, the quantity of solid particles carried out overhead is progressively decreased to a lower limiting value. Pursuant to the present process, it is greatly preferred to maintain such conditions that only a relatively small quantity of solid particles is carried out with the efliuent gaseous component since the equipment for recovering of such material from the gaseous component is thereby greatly simpliiied and reduced in cost.

From outlet lines II vaporous reaction products are passed by manifold I'I and line I8 to suitable means for recovering the residual quantity of catalyst particles remaining therein and thereafter to suitable recovery means for condensation and separation into the desired products.

From manifold I'I' the vaporous reaction products may be passed by line I8 to a suitable gassolids separating equipment, such as cyclones or the like, indicated diagrammatically by the numeral E. From separator 6 the vaporous reaction products are passed by line I9 to a fractionator or similar apparatus of conventional design and hence not illustrated. Separated residual catalyst withdrawn from separator 6 may suitably be returned to the catalyst stripping Zone 2li in reactor 2 by catalyst return line 2 I After passing in contact with the hydrocarbon yapors, the uid mass of spent catalyst particles is preferably subjected to a stripping operation .to remove adsorbed or entrained hydrocarbon vapors therefrom prior to the passage of these particles to the regeneration stage. This strip- .ping operation may suitably be effected in a distinct stripping zone 2l) within the reactor and ,defined by the space between the end of the reactor and baffle 2l. A suitable aerating and stripping medium such as steam is supplied to the lower portion of this stripping zone by line 22 to a steam ring or other suitable distributing meansv 23 disposed in the lower portion of the stripping zone. The stripping medium is supplied in such quantities that it passes through ping medium andstrippedvapors may suitably be withdrawn overhead from the stripping zone through line 24 and combined with the vaporous reaction products in line I8.

Spent catalyst may be suitably' withdrawn from the base of the reactor through a valved catalyst standpipe 25.` Standpipe 25 is preferably provided with an enlarged portion I4 at the upper end thereof to which an aerating and stripping medium may be introduced through line 26 and distributors 29' for the purpose of maintaining the withdrawn catalyst in a readily flowable condition and also to effect additional stripping action. Additional aerating fluid is preferably introduced at suitably spaced points along the length of standpipe 25 through lines 28 to maintain the catalyst therein'.` in a readily ilowable condition. i

As illustrative of suitable operating conditions in the practice of the invention as applied to the catalytic conversion of a petroleum gas oil feed stock to low boiling hydrocarbons within the motor fuel boiling range, there is given in the following Table A suitable conditions for such a unit `based upon a feed capacity of` 10,000 bbls./day of the gas oil feed. The catalyst for this operation consisted of an activated clay known commercially as Super-Filtrol in a fine- 1y divided or powdered condition, that is, of a fneness suicient to pass a 100 mesh screen and consisting largely of particles of indiscriminately mixed sizes smaller than 100 microns in average diameter.

Table A Gas `oil feed, bbls./day` 10,000 Steam feed, lbs./hr. 13,000 Reactor dimensions, (a) length, ft 50 Reactor dimensions., (b) diameter, ft 12 Feed weight ratio of "catalyst to oil 5 "The regeneration operation is preferably effected in accordance with the same principles as the conversion stage, except that in the latter case the gaseous component contacted with the catalytic particles consist of an oxygen-containing gas such as air. Also, in the regeneration stage a portion of the regenerated catalyst is preferably recycled to the regeneration zone with intervening cooling of the recycled stream of catalyst for the purpose of temperature control within `the regeneration zone. Optionally, a simi-` lar recycle stream of used catalyst may be employed if desired in connection with reactor 2 with intervening heating if this recycled stream of spent catalyst, or cooling, as desired for the purpose of temperature control Within the conversion zone or for varying the average degree of catalytic :activity of the catalyst mass.

Spent catalyst may be suitably introduced into regenerator 3 `by catalyst standpipe .25 leading directly thereto whereby the transfer `of catalyst from the reactor to the regenerator is effected entirely by gravity flow. The enteringstream of spent catalyst particles meets and is intimately mixed With the stream of cooled recycled catalyst introduced through catalyst inlet 26. An oxygen-containing gas, preferably air, is introduced at the base of the regenerator through manifold 21 and branch valved lines 2l'. Air is supplied through lines 21 in such quantity that the mass of catalyst particles thereabove is maintained in a freely owable but relatively dense state. In this case similar to that prevailing in the conversion zone the mass of relatively dense aerated catalyst resembles a liquid in its flow characteristics and is positively displaced laterally through the regeneration zone by the addition of catalyst particles at one end portion and the Withdrawal of catalyst particles at the opposite end portion. i

, The height of the catalystlevel 28 is controlled in accordance with the same principlesof operation described for level I3, so that under preferred conditions a relatively small quantity of catalyst particles is withdrawn overhead with the regeneration gases through regeneration gas outlets 29.

A stripping zone 30 is provided at the catalyst outlet end of the regenerator similar to stripping zone 20 for the purpose of stripping oxygencontaining gases from the regenerated catalyst. A suitable stripping medium such as steam `is supplied to zone 30 through line 3l and distributing means 32.

The regenerated catalyst is withdrawn in two separate streams through catalyst standpipe`s33 and 34. Standpipes 33 and 34 may each be provided at the upper end portion thereof With`an enlarged section 35 and 36, respectively', similar to I4 and provided with means 31 and 3&8 for introducing a stripping gas thereto. Standpipes 33 and 34 are further provided with lines139 and 40, respectively, spaced at suitable points along their length for introducing steam or other aerating medium to maintain the catalyst therein in a freely ilowable condition.

From valve 39 in catalyst standpipe 34 regenerated catalyst is forwarded to the conversion zone through transfer line I 0 as previously described. From catalyst standpipe 33, the 'quantity of regenerated catalyst withdrawn is that required for temperature control within the regeneration zone 3. Dependent upon the type of catalyst or contact material employed there is nor mally a maximum regeneration temperature which should not be exceeded, for example in the case of a cracking catalyst consisting of an activated clay of the Super-Filtrol type thistemperature is normally taken as about 1100 to 1150 F.

Recycled catalyst is fed by valve 40 from catalyst standpipe 33 into a stream of a conveying fluid, suitably `air derived from compressor 4, through line 4I and passed by line 42 through a heat exchanger 43 through which a cooling medium is circulated by lines 44 and 45. In exchanger 43 the stream of recycled catalyst is cooled to a temperature adapted to provide the desired temperature control during the regeneration operation. A balile 4B may be provided at the outlet of catalyst inlet 26 to subserve the same purpose as baffle I2.

Gaseous combustion products are withdrawn overhead from regenerator 3 through outlets `29 and are passed to a. suitable gas-solids separating system to separate catalyst particles suspended therein. The quantity of catalyst carried overhead,`as in the case of the reaction zone, is preferably maintained at a relative low amount thereby greatly simplifying the recovery system necessary for the separation of this material from the gas component. The stripping medium and stripped gases exiting from zone 30 may suitably be combined with the eilluent gas from outlets 29 by line 41. The effluent regeneration gas may be passedl through a cooler or heat exchanger 48 prior to passage to the gas-solids separating system, although this cooling step may optionally be omitted. From heat exchanger 48 the gas mixture passes by line 49 to a suitable gas-solids separator such as a Cottrell precipitator, a cyclone separator, or the like, wherein the small quantity of suspended solids may be suitably separated. In lseparator 5, the flue gas is withdrawn overhead through line 50 and the separated solids are withdrawn at the bottom through hopper 5l. Any required amount of make up catalyst may be supplied to hopper 5l from fresh catalyst hop-per I6. v From hopper 5I the recovered catalyst is returned by catalyst standpipe 52 to the regenerator'by transfer line 53 to which a suitable conveying fluid such as steam is supplied by line 54.

Operating conditions suitably maintained in the regeneration stage of the process are illustrated by the conditions tabulated in the appended Table B for a regeneration operation corresponding to the conversion operation given in Table A.

Table B spent catalyst, lbs/hr 632,840 Cooled recycled catalyst, llos/hr 900,000 Ratio by weight recycled to spent catl alyst A1.43 Inlet temperature, spent catalyst, F 900 Inlet temperature, recycled catalyst, F 700 Outlet temperature of c at a l y s t and gas, F 1,000 Regenerator dimensions: l

(a) Length, ft 72 (b) Diameter, ft 20 Regenerator gas velocity, ft./sec 0.5

Air feed, lbs/hr 91,000 Catalyst concentration:

(a) Regenerator, lbs/cu. ft 23 (b) Outlet gas, grains/ cu. ft 20 Weight percent of coke produced based on oil feed 5.0 Coke percent .by weight on spent catalyst 1.3 Carbon percent by weight on regenerated v catalyst 0.7 Catalyst contact time, seconds 615 Pressure in regenerator, lbs/sq. in '7 Horizontal catalyst velocity, ft./sec 0.12

Certain variable operating conditions in the practice of the process may follow and be controlled pursuant to conventional practice in the art with respect to the particular conversion or treating reaction involved. For example in the application of the process to the vapor phase catalytic cracking of high boiling hydrocarbons to low boiling hydrocarbons within the motor fuel boiling range, such factors as the selection of suitable charging stock, catalytic material, conversion temperatures, pressures, and the like, may be determined in accordance with conventional practice in this particular art.

The rate of fresh catalyst feed is dependent upon the desired average catalytic activity of the dense phase of catalyst in the conversion zone, and fresh catalyst is continually added at a rate adapted to maintain such activity at the desired value as the conversion proceeds. Used catalyst is withdrawn at the same average rate as fresh catalyst is added, therefore, the average time a catalyst particle remains in the reactor (catalyst residence time) is determined by the catalyst feed rate and may be calculated by dividing the Weight of catalyst in the reactor by the catalyst feed rate per minute. Y

The weight of catalyst in the reactor is depend ent upon the concentration of the dense phase and the height of the upper level of this phase. In the application of the process to the catalytic cracking of high boiling hydrocarbons it is preferred to maintain the ratio of the weight of oil fed per hour to the weight of catalyst in the reaction zone (w./hr./W.) within the range of about 1.0 to 25.0 and preferably within the more restricted range of about 2.5 to 10.0. Also, in this case it is preferred to utilize a catalyst to oil feed rate ratio within the range of 0.5:1 to 20:1 and preferably within the more restricted range of The velocity of the gaseous component preferably maintained in the practice of the process is dependent upon the character of the catalytic particles employed with respect to such factors as their individual size, shape and density. The gaseous component should be maintained at a velocity of sufcient magnitude to aerate the mass of catalyst particles to an extent sufficient to maintain them in a readily flowable condition. Further, the maximum velocity must not be in excess of that velocity below which a relatively dense or concentrated phase of the catalyst particles is produced in the solids-vapor contact zone. At relatively high vertical gasv velocities the catalyst particles may be suspended in the stream of gas and carried along therewith at a velocity approaching that of the gas particles. At relatively low vertical gas velocities the effect of the phenomenon known as "slip becomes pronounced and in the zone of such low velocities the solid catalytic particles accumulate, thereby producing a relatively dense or concentrated phase. In the practice of the present process lateral internal recycle is avoided. The avoidance of such recycling isprovided by the horizontally elongated configuration of the conversion and regeneration zones, and the relative thinness of the bed ofI catalyst compared to its length. Under these conditions, it is apparent that the carbonaceous content of the laterally moving bed is progressively increased in the direction of flow in the conversion zone, and that the converse is true in the regeneration zone. Accordingly, the quantities of the gaseous component admitted through each of the valved lines, 6 and 21 may be adjusted with respect to the carbon concentration of the catalyst above the individual gas inlets.

Since reactor 2 and regenerator 3 are of uniform diameter the average lateral velocity of the particles therethrough will be substantially uniform. This velocity may be varied toadvantage in certain instances by modifying the cross-sectional area in various parts of the reaction vessel, for example, by gradually increasing this area in the direction of lateral flow the velocity of the catalyst particles will be progressively lower in the direction of flow. Likewise the thickness of the catalyst bed may be varied in different parts of the reaction zone by suitably contouring the bottom of the reaction vessel. This same effect may also be produced by inclining the reaction vessel whereby the bed will be so disposed that it gradually increases or decreases in thickness in the direction of ow dependent upon whether the inlet end of the reaction vessel is made higher or lower than the outlet end.

Any of the various known types of cracking catalyst may be utilized in the practice of the invention. The preferred catalysts are those of the silica-alumina, or silica-magnesia type adapted to produce a satisfactory yield of high octane gasoline. Either silica-alumina catalyst consisting of activated clay prepared by the acid treatment of natural clays, for example the commercial product Super-Filtrol or a synthetically prepared silica-alumina catalyst such as those disclosed in copending applications of Robert Ruthruir', Serial Nos. 305,472 now U. S.

Patent 2,391,481 and 305,473 now U. S. Patent 2,391,482, both filed November 2l, 1939, may be employed. The catalyst is preferably employed in iinely divided or powdered condition, for example with particles ranging from about l to 100 microns. However, :granular catalyst particles may be employed, and in this instance a mixture of granular and powdered catalytic material is preferred.`

Pursuant to the preferred embodiment of the invention, the conversion zone and the regeneration zone are `maintained under substantially the same pressure that is 7 lbs/sq. in each as set forth in Tables A and B. The maintenance of this condition has the important advantage of minimizing the application of pressure and the height of standpipes- 25 and 34 necessary to transfer catalyst in the cyclic circulation between the zones. The arrangement of one of the zones at a diiferent horizontal level than the other zone interconnected directly by a standpipe 25 `provides for direct gravity ow of the catalyst without the necessity of providing a carrier line in which the catalyst is carried in suspension. A further feature of the iiow illustrated is the use of a non-reactive gas, for example steam in carrier line lll to transfer the catalyst between the zones independently of the now of reactant gas and vapors. Standpipe 25 similarly may be arranged to discharge into a carrier line similar to line H) and the reactor and regenerator thereby placed on the same horizontal level or in a cornmon housing. The flow of purging gas., particularly steam through zone 20 in parallel ilow with the hydrocarbon vapors in reactor 2, is especially advantageous in its avoidance of intermingling of the purging fluid with the catalyst in zone 2 and consequent acceleration in catalyst deactivation. These and similar features, both individually and in combination, are important features of our process and are the subject of the following claims.

I claim:

1. In a process for contacting solids and gases by passing said gases upwardly through a mass of said solids in iinely-divided form in a reaction zone at a velocity such that said mass of solids are maintained in a state of separation into a lower dense phase resembling a liquid in its iiow characteristics, and an upper dilute phase of substantially lower solids concentration, an improved method of introducing and flowing said solids through said reaction zone which includes the steps of: upwardly introducing a confined stream of solids suspended in gases into said reaction zone at an elevation above the surface of said dense phase; deflecting said upwardly introduced stream downwardly onto an upper surface oi' said dense phase; flowing said dense phase mass substantially horizontally away` from said point of introduction to a point of withdrawal of dense phase solids; withdrawing eiiiuent vapors from said reaction zone from said dilute phase therein at a point above said point of deflection of said incoming stream.

2. In a catalytic conversion system of the iluidized catalyst type, wherein the reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adapted to maintain said mass in a dense flowable liquid-simulating condition, and wherein spent catalyst is continuously withdrawn from said reaction zone and regenerated in separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone which method includes the steps of: flowing catalyst in a liquid-simulating condition from said reaction zone dense phase through a restricted opening, communicating directly and exclusively with the dense mass of catalyst in the reaction zone and into a stripping-zone separate from said reaction zone dense phase; stripping residual vapors from said withdrawn catalyst in by means of stripping gas; withdrawing the vaporous products from said reaction zone dense phase; withdrawing stripping gases and stripped vapors from said stripping-zone; and combining said vaporous products withdrawn from said reaction zone dense phase and said stripped gases withdrawn from said stripping zone dense phase.

3. A method of contacting solid particles and gaseous duid which comprises introducing subdivided solid particles and gaseous iiuid into a contacting zone and maintaining the particles as a fluidized dense liquid-simulating mixture in said reaction zone, withdrawing dense luidized solid particle mixture from the lower portion of said contacting zone and passing it to the bottom of a separate stripping zone, introducing stripping gas into the lower portion of said stripping zone at a velocity selected to maintain the particles in a dense fiuidized liquid-simulating condition during stripping, removing stripped particles from the bottom portion of said stripping zone in a` dense iluidized condition and removing stripping gas and stripped-out constituents from the upper portion of said stripping zone.

4. A method according to claim 3 wherein the gaseous fluid contains only a small amount of entrained catalyst in the upper portion of said contacting zone and the stripping gas from the top of said stripping zone is combined directly with the gaseous fluid withdrawn from the upper part of said contacting zone above the dense mixture.

5. A method according to claim 3 wherein the gaseous fluid contains only a small amount of entrained catalyst in the upper portion of said contacting zone and the stripping gas from the top of said stripping zone is combined with said gaseous fluid containing only a small amount of entrained catalyst.

5. In a method of contacting solid particles and a gaseous uid in a contacting zone wherein the particles are maintained as a dry dense liquidsimulating mixture, the improvement which comprises passing the dry dense mixture from the bottom portion of said contacting zone to the bottom portion of a separate stripping zone to remove entrained gaseous iiuid and wherein the particles are maintained as a dense iiuidized mixture, introducing stripping gas into the bottom portion of said stripping zone and withdrawing ydense iiuidized stripped contact particles from the. bottom portion of said stripping zone and withdrawing stripping gas together with strip-nedout constituents from the upper portion of said stripping zone.

'7. In a catalytic conversion system nf the. fluidiynd. nai-,alv/:t -vria wherein reactant V'ahf'ws 2,179, pageed unwavdlv through a, mass of natalvst in a reaction zope at a velonitv adapted tn maintain said mass in a, stai-.Q nf senaratinn into a lower dence, phase in a. flmvahle. Hemd-simulatl'lU nnhfitfin QYifl 911 Tinley filn-n ribose 0f S1111- stapt-5911i? natalvc, mi wher-pin crient nato'vef, is nmntinnnuelv mii-hf-lv-awn from said reaction zone and regenerated in a `separate regeneration zone. an improved method for withdrawing and stripping spent catalyst from said reaction zone. which method ,includes the steps of: flowing dense phase catalyst in a uniud-simulating condition from below the surface of said reaction zone dense phase. through a restricted opening, and into a stripping-zone dense phase. below the surface thereof. said stripping-zone dense phase being maintained in a stripping zone distinct from said reaction zone. but communicating therewith by means of said restricted opening connecting the dense phases of the two zones; introducing stripping gases upwardly through said stripping zone at a velocity adapted to maintain catalyst therein in a state of separation into a stripping-zone dense phase and an upper dilute phase of substantially reduced catalyst concentration, said stripping-zone and reaction-zone dilute phases being maintained separately from one another in said stripping zone and said reaction zone respectively; separately withdrawing vapors from said reaction zone and said stripping zone from their respective dilute phase regions; and withdrawing catalyst from the lower portion of said strippingzone dense phase for transfer to said regeneration zone.

8. In a catalytic conversion system of the fluidized catalyst type, wherein reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adapted to maintain said mass in a state of separation into a lower dense phase in a fiowable liquid-simulating condition and an upper dilute phase of substantially lower catalyst concentration, and wherein spent catalyst is continuously withdrawn from said reaction zone and regenerated in a separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone, which method includes the steps of: continuously flowing a part of said reactionzone dense phase substantially horizontally through a restricted opening below the surface of said dense phase into a stripping zone out of the path of said vapors; introducing stripping gases upwardly through said stripping zone at a velocity adapted to maintain catalyst therein in a state of separation into a stripping-zone dense phase and an upper dilute phase of substantially reduced catalyst concentration, said strippingzone and reaction-zone dilute phases being maintained separately from one another in said stripping zone and said reaction zone respectively; separately withdrawing vapors from said reaction zone and said stripping zone from their respective dilute phase regions; and withdrawing catalyst from the lower portion of said strippingzone dense phase for transfer to said regeneration zone.

9. In a catalytic conversion system of the uidized catalyst type, wherein reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adapted to maintain said mass in a state of separation into a lower dense phase in a nowable liquid-simulating condition and an upper dilute phase of substantially lower catalyst concentration, and wherein spent catalyst is continuously withdrawn from said reaction zone and regenerated in a separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone, which method includes the steps of flowing dense phase catalyst in a liquid-simulating condition from below the surface of said reaction zone dense phase, through a restricted opening, and into a stripping-zone dense phase, below the surface thereof, said stripping-zone dense phase being maintained in a stripping zone distinct from said reaction zone, but communieating therewith by means of said restricted opening connecting the dense phases of the two zones; introducing stripping gases upwardly through said stripping zone at a velocity adapted to maintain catalyst therein in a state of separation into a stripping-zone dense phase and an upper dilute phase of substantially reduced catalyst concentration, said stripping-zone and reaction-zone dilute phases being maintained separately from one another in said stripping zone and said reaction zone respectively; Vseparately withdrawing vapors from said reaction zone and said stripping zone from their respective dilute phase regions; downwardly withdrawing a dense iiowable column increasing in pressure in the direction of flow from the lower portion of said stripping-zone dense phase; and transferring catalyst from the base of said column to said regeneration zone.

10. In a catalytic conversion system of the fiuidized catalyst type, wherein reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adapted to maintain said mass in a state of separation into a lower dense phase in a iiowable liquid-simulating condition and an upper dilute phase of substantially lower catalyst concentration, and wherein spent catalyst is continuously withdrawn from said reaction zone and regenerated in a separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone, which method includes the steps of: ilowing dense phase catalyst in a liquid-simulating condition from below the surface of said reaction zone dense phase, through a restricted opening, and into a stripping-zone distinct from said reaction zone and communicating therewith only by means of said restricted opening for discharging spent catalyst from said reaction zone into said. stripping zone; introducing stripping gases upwardly through said stripping zone at a velocity adapted to maintain catalyst therein in a state of separation into a stripping-zone dense phase and an upper dilute phase of substantially reduced catalyst concentration, said strippingzone and reaction-zone dilute phases being maintained separately from one another in said stripping zone and said reaction zone respectively; separately withdrawing vapors from said reaction zone and said stripping zone from their re` spective dilute phase regions of said reaction zone and said stripping zone are then combined and passed to centrifugal gas-solid separating means for recovery of residual entrained solids.

12. In a catalytic conversion system of the fluidized catalyst type, wherein reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adapted to maintain said mass in a state of separation into a lower dense phase in a flowable liquid-simulating condition and an upper dilute phase of substantially lower catalyst concentration, and wherein spent catalyst is continuously withdrawn from said reaction zone and regenerated in a separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone, which method includes the steps of: ilowing dense phase catalyst in a liquid-simulating condition from below the surface of said reaction Zone dense phase, through a restricted opening, and into a stripping zone separate and distinct from said reaction zone; introducing 1 stripping gases upwardly through said strippingzone at a velocity adapted to maintain catalyst therein in a state of separation into a strippingzone dense phase and an upper dilute phase of substantially reducedcatalyst concentration, said stripping-zone and reaction-zone dilute phases being maintained separately from one another in said stripping zone and said reaction zone respec tively; ilowing vapors upwardly from said reaction-zone `dense phase and said stripping-Zone `dense phase through the separate dilute phase regions above said respective dense phases; combining vapors being withdrawn from the upper part of said reaction-zone and said stripping-zone dilute phase regions; and withdrawing catalyst from the lower portion of said stripping-zone dense phase in a llowable liquid-simulating condition and an upper dilute phase of substantially lower catalyst concentration, and wherein spent catalyst is continuously withdrawn from said reaction zone and regenerated in a separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone, which method includes the steps of continuously flowing a part of said reaction-zone dense phase laterally through a restricted opening below the surface of said dense phase out of said dense phase and into a stripping zone out of the path of said vapors; introducing stripping gases upwardly through said stripping zone at a velocity adapted to maintain catalyst therein in a state of separation into a stripping-zone dense phase and an upper dilute phase of `substantially reduced catalyst concentration, said dense phase for transfer to said regeneration zone.

` 13. In a catalytic conversion system of the uidized catalyst type, wherein the reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adaptedl to maintain said mass in a state of separation into a lower dense phase in a flowable liquid-simulating condition and an upper dilute phase of substantially lower catalyst concentration, and wherein spent catalyst is continuously withdrawn from said reaction zone and regenerated in a separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone which method includes the steps of: flowing dense phase catalyst in a liquid-simulating condition from said reaction zone dense phase, through a restricted opening below the surface of said densephase and into a stripping zone separate from said `reaction zone dense phase and said reactant vapors; stripping residual vapors from said withdrawn catalyst by passing stripping gas upwardly through said catalyst` in said stripping zone; withdrawing the vaporous products from said reaction zone dense phase; separately withdrawing stripping gases and stripped vapors from said stripping zone; combining said vaporous products withdrawn from said reaction zone dense phase and said stripped gases withdrawn from said stripping zone dense phase; withdrawing catalyst from said stripping zone for transfer to said regeneration zone.

14. In a catalytic conversion system of the iluidized catalyst type, wherein reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adapted to maintain said mass in a state of separation into a lower stripping-zone dilute phase being maintained separately from said reaction zone; flowing vapors upwardly from said reaction-zone dense phase and said stripping-zone dense phase through separate dilute phase regions above said respective dense phases; combining vapors being withdrawn from the upper part of said reactionzone and said stripping-zone dilute phase regions; and withdrawing catalyst from the lower portion of said stripping-zone dense phase for transfer to said regeneration zone.

15. In a catalytic conversion system of the fluidized catalyst type, wherein reactant vapors are passed upwardly through a mass of catalyst in a reaction zone at a velocity adapted to maintain said mass in a state of separation into a lower dense phase in a flowable liquid-simulating condition and an upper dilute phase of substantially lower catalyst concentration, and wherein spent catalyst is continuously withdrawn from said reaction Zone and regenerated in a separate regeneration zone, an improved method for withdrawing and stripping spent catalyst from said reaction zone, which method includes the steps of: ilowing catalyst in said dense condition from said reaction zone dense phase below the surface thereof through a restricted opening into a stripping zone separate and distinct from said reaction zone; introducing stripping gases upwardly through said stripping zone at a velocity adapted to maintain catalyst therein in a state of separation into a stripping-zone dense phase and an upper dilute phase of substantially reduced catalyst concentration; maintaining said stripping-zone dilute phase separate from said reaction zone to settle entrained particles from stripping vapors without recontacting said settling particles with reaction vapor; flowing vapors upwardly from said reaction-zone dense phase and said stripping-zone dense phase through separate dilute phase regions above said respective dense phases; combining vapors being withdrawn from the upper part of said reaction-zone and said stripping-zone dilute phase regions; and

withdrawing catalyst from the lower portion of' said stripping-zone dense phase for transfer to said regeneration zone.

References Cited in the file of this patent UNITED STATES PATENTS Keith et al. July 18, 1950

Claims (1)

1. 3. A METHOD OF CONTACTING SOLID PARTICLES AND GASEOUS FLUID WHICH COMPRISES INTRODUCING SUBDIVIDED SOLID PARTICLES AND GASEOUS FLUID INTO A CONTACTING ZONE AND MAINTAINING THE PARTICLES AS A FLUIDIZED DENSE LIQUID-SIMULATING MIXTURE IN SAID REACTION ZONE, WITHDRAWING DENSE FLUIDIZED SOLID PARTICLE MIXTURE FROM THE LOWER PORTION OF SAID CONTACTING ZONE AND PASSING IT TO THE BOTTOM OF A SEPARATE STRIPPING ZONE, INTRODUCING STRIPPING GAS INTO THE LOWER PORTION OF SAID STRIPPING ZONE AT A VELOCITY SELECTED TO MAINTAIN THE PAR-

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