US 2394710 A
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Description (OCR text may contain errors)
Feb. 12, 1946. J, MCAFEE 2,394,710
CONTACTING FLUIDS WITH SOLIDS f' Af-@A7 f 12, 1 MCAFEE l coNTAcTING FLUIDS WITHSOLIDS Filed Aug. 50, 1945 5 Sheets-Sheet 2 OX/D/Z/NG I (afa/gsi Frown Feb. 12, 19464. J, MQAFEE 2,394,710
' CONTACT-ING FLUIDS WITH soLIDs l Filed Aug. 50, 1./943 V 5 Sheets-Sheet 5 y a yezzeraor 1319 140 ax/o/z//VG ?atented Feb. 12, 1946 UNITED srA'ras coN'rAc'riNG FLUins soun Jerry McAfee, Riverside,
Oil Products Company,
tion of Delaware Application August 30,
The invention is directed to an-improved process of the type in which subdivided solid particles are contacted with a fluid either in the form of liquid, vapor or gas or in mixed ph'ase for the be evident to those familiar with the Illi, assignor to Universal Chicago, Ill., a corpora- 1943, serial No. 50am (Cl. ISG-52) airt from the following description and explanat on.
Catalytic cracking i hydrocarbon oils las now commonly practiced employs substantially non-v purpose of effecting treatment or conversion of combustible subdivided solid catalyst -either in either the solid material or the iluid for effecting granular, pulverulcnt or other particle form, such' a reaction therebetween. as spheres or spheroids, cylindrical shapes and The invention is morey particularly ldirected to the like, for promoting the cracking reaction. In improvements in that type of process wherein a general, this type of catalyst comprises silica'coml iiud reactant is converted while in contact with posited with one or more metal oxides of which a mass of substantially non-combustible, subdialumina and zirconia are the most commonly vided solid particles, such as catalyst, for promotemployed. In cracking oil to produce lighter fracing the desired reaction or relatively inert solid tions. such as gasoline; heavier fractions are also contact material and upon which deleterious comproduced and some of them accumulate on the bustible deposits are formed as a result of said catalyst particles as carbonaceous or hydrocarreaction, th'e contaminating deposits being conbonaceous deposits which reduce the activity of tinuously or periodically removed to regenerate the catalyst for promoting the cracking reaction the contact material. The regeneration ordi- Such contamination ofthe catalyst is encounnarily comprises oxidation or burning of the comtered in many other catalytoally -lorornoted hybustible deposits and may be accomplished for drocarbon conversion reactionsaswellasinth'erthe purpose of restoring catalytic activity or to mal hydrocarbon conversion processes employing store heat in the contact mass for subsequent use relatively inert contact material, such as silica, in promoting conversion of the iluid reactants, in quartz Dumme, Val'iOuS Clays POSSCSSlIlg little 01' case the reaction is endothermic, or for any other n0 Catalytic activity kaoln, dtomacolls earth desirable purpose,l such as, for example, to preand the likevent excessive agglomeration of the particles oi This Comtamlnatn 0f the Catalyst necessitates subdivided solid contact material which would its regeneration between Periods of use in pro-v resulting plugging of the bed thereof in the ma@ moting the hydrocarbon conversion reaction, said tion zone or excessive channeling of the iiuid reregeneration Ordlnarny being accomplished by actants throughthe bed without proper contact. burning the contaminating combustible deposits The invention is particularly concerned with from the catalyst particles in a stream of oxidizing improvements in the regeneration of substan. gas such as, an or an diluted with combustion tially noncombustible subdivided solid Acontact gases 0.1 .o t'her relatlvely inert gas' Due to the, material contaminated with' combustible deposits 35 'Susceptlblhty of the ,catalyst ifo, damage or Per' for the purpose of removing 1:he latten It also manent impairment of its activity at excessively involves the processv in which said combustible high temperatures* the maxlmum temperature contaminants are deposited on the contact ma- Wmh it encounters in the regeneratingstep must ,Serial and Vario-u be limited by careful control of the regenerating s combinations of this latter step with the improved method of regeneration rooperatlon' Wlth Syntheticauy prepared crackmg K vided by the invention l p 10 catalyst or treated natural clays from which sub- The Catalytic conversc of h drocarbon b stantially all alkali metal compounds have been vaou ed min t-,n a t n y h, S 'ky excluded or removed, the permissible maximum l .S pr o ai 1 g r9 C 1C.) sxsuc as ajc regenerating temperature is within the approxiing, dehydrogenatlon, aromatlzation and various mate range of 1200 to 1400s F. and for safety the combinations of such reactions., exemplify coxnregenerating temperature-is usually limited to IflefclallyA lmportant. Processes 1n which the 11n- 115o F. or tnereabouts. substantially the same provements provided by the invention will be or Slightly higher temperatures are commonly found particularly advantageous. To concretely employed in the regeneration of dehydrogenatmg expljnn 'the featufss and advantages 0f the mand aromatizing catalyst such as subdivided solid Ventlon, then appllcatlOn t0 a PrOCeSS fOr Catas0 particles of alumina composited with one or more lytcally cracking hydrocarbon Oils h'aS been chO- other metal oxides, including the oxides of chrosen as an example and the subsequent descrpmium, thorium, molybdenum, vanadium, tungtion will be princ1pa1ly directed thereto. The apsten, chromium sesquioxide being the most complicability of the invention to other specific procmonly'employed. esses will The most modern and advanced catalytic crackating zones, contaminated catalyst being continuously transferred from the cracking zone to the regenerating zone and regenerated catalyst being continuously transferred from the regenerating zone back to the crackin: zone.
Present commercially significant processes of this general class are of two types. In one type known as uid bed resulting iiuid products (oil vapors and resulting the regenerating temperature can I avoid overheating of the heat exchanger type.
operation, the mass or bed l0 Thus, in iiuid 'bed operations it is ordinarily? With the other commercial type of moving bed operation, the catalyst particles pass through the reaction and regenerating zones as a relatively means, other than iiuidization, for substantially equalizing temperatures in the regenerating zone Aing processes involve the continuous cyclic transthe catalyst passes in close proximity to relatively,y
spaced tubular elements or vthe like 'through generated.
Catalyst activity is an may even be many other catalytically promoted hydrocarbon conversion reactions, even though a high order of catalyst activity ls not necessary, it will give improved results and/or give economy of operation by permitting a, reduction in the reaction temperaturel or the use of a lesser total volume or weight of catalyst in the reaction zone, the latter permitting the use of a smaller reaction vessel for a given charging stock capacity and percent con-VV version.
One of the primary objects of the invention is to provide a method for regenerating contaminated or spent catalyst or contact material which will give more complete regeneration (i. e., more complete removal of the contaminating deposits than can ordinarily be accomplished with the iiuid bed technique).
A further object of the invention is to accoml plish the aforesaid more complete regeneration of subdivided solid catalyst or contact material and by regenerating the subdividedl solidycatalyst or;
contact material in a sequence -vof steps, through one of which the solid particles are passed in the form of a Huid-like mass, and passing resulting partially regenerated lsolid particles through a subsequent step of the regeneration as a relatively compact mass wherein the further and more complete removal of contaminating deposits is accomplished.
In order to obtain the second objective above stated, the regeneration is preferably carried to a suiiicient degree of completion while the catalyst mass isin a fluid-like state that all or a substantial portion of the remaining deposits can be burned from the compact bed in the succeeding step without encountering excessively high tem- -peratures in the latter. This does not necessarily mean that a'positive control of the regenerating temperature is not employed in either the last mentioned or the first mentioned step of the regeneration, but that such positive control can be accomplished by relatively simple and inexpensive methods and means which obviate the necessity for a regenerating vessel having a large and well distributed heat exchange surface.
The invention contemplates the two-stage or multiple stage method of regeneration above outindicated'at I2, is mounted in the upper head of the vessel anda periorate plate or distributing grid for incoming fluid reactantsl and catalyst particles is disposed within the vessel substantially at the juncture of the cone bottom with the cylined as applied to various types of operation in l between the stages of the regeneration, aswell as between the regenerating zone and the reaction l Zone.
The aforementioned and other features and advantages of the process provided by the invention will be apparent with reference to the accompanying diagrammatic drawings and the following description thereof. The drawings illustrate several forms of apparatus in which the process provided by the invention may be conducted and several specific embodiments of the process.
Figure 1i of the drawings illustrates one specific form of apparatus in which the process provided by the invention may be conducted. employingl a fluid-like bed of subdivided solid catalyst or contact material in the reactor and in the rst stage regenerator and in employing a compact bed in the second stage regenerator. y
Figure 2 illustrates a modification of the apparatus and iiow shown in Figure 1.
Figure 3 illustrates another specificform of apparatus in which the process provided by the invention may be conducted, employing two stages of regeneration. the first of which is conducted with the catalyst or contact material in theform of a fluid-like bed while thebed of catalyst or contact material in the second regenerating step is maintained in a compact condition, and employing either a fluid-like or relatively compact bed of catalyst or Contact material in the reactor.
Figure 4 illustrates a modification of the form of reactor shown in Figure 3 in which the reactants and resulting iiuid conversion productsare passed downwardly rather than upwardly through a downwardly moving compact bed of catalyst or contact material in this zone.
Figure 5 illustrates another specic form ofreaction vessel in which two stages of regeneration may be accomplished in accordance with the features of the invention;
Referring now particularly to Figure l, the reaction vessel in which a catalytically promoted hydrocarbon conversion reaction, such as catalytic cracking, for example, may be conducted is indicated at II and comprises a vertically disposed, substantially cylindrical vessel closed at its opposite ends, thevlower head being oi' substantially lindrical shell,'as indicated at I3.
'I'he hydrocarbons to be converted are supplied through line I 4 and valve I5 to transfer line I 6 wherein they commingle with hot regenerated catalyst, as will be later described, and through which the catalyst is'transported, principally by the lifting action of the hydrocarbons with which it is commingled, into the lower portion of reactor II. The reactants and resulting fluid conversion products are directed upwardly through the reactor under conditions of temperature, pressure and space velocity regulated to eect the desired conversion reaction in the presence of a catalyst.
"The term "space velocity as herein used 'refers to the quantity or weight of reactants supplied to the reaction zone in a given time per unit quantity or weight of catalyst or contact material present in the reaction zone. Except where otherwise indicated, it will be hereinafter expressed on a weight hourly basis V(i. e.,.poun'ds of reactants supplied to the reaction zone per hour, per pound of catalyst or contact material present in the reaction zone) y In the operation here illustrated, the rates of catalyst introduction and removal from the reaction zone are substantially the same during normal operation of the process, but a concentration of catalyst particles greater than that prevailingin the incoming stream of iluid reactants with which they are supplied to the reaction zone is maintained in the fluid-like catalyst bed "within the reactor. between the linear velocity of theiluid reactants and conversion products passing upwardly through the bed and the average weight and size of the catalyst particles to give hindered settling of the catalyst particles in the iiuid bed due to the lifting action of the fluid reactants and conversion products working opposite tothe force of gravity on the catalyst particles. Hindered settling is reduced or substantially eliminated in the upper portion of the reactor and, with the particular mode of catalyst circulation here illustrated, there is a relatively sharp line of demarkation between the fluid bed proper, in which there is pronounced hindered settling and a high catalyst particle concentration, and a zone at the upper end of the reactor, known as the light` phase, in which hindered settling and catalyst particle concentration is greatly reduced. The approximate line of demarkation between the dense phase fluid bed and the light phase in the reactoris indicated at I1.
The fluid conversion products and entrained catalyst particles are directed from the light phase in the upper portion of the reactor to the cyclone separator I2, wherein at least a major portion of the entrained solid particles are separated and returned, in the case illustrated, from the lower portion of the separator through standpipe I 8 to the relatively dense fluid bed in the reactor. The iluid reactants are ldirected from separator I2 through line I9 and the pressure control valve 20 to suitable 'further separating, fractionating and recovery equipment not pertinenty to the present invention and not here illustrated. i
A stream of catalyst particles is directed down conical form. Suitable separating equipment for -catalyst particles, such as the cyclone separator This is the result of a correlation wardly through standpipe 2l, the open upper end of which terminates at any desired point in the\ relatively dense uid-like catalyst-bed in the reactor, and through a suitable adjustable orifice `or flow control valve 22 adjacent its lower end to transfer line 23, wherein the catalystparticles are picked up by an incoming stream of air or other oxidizing gas supplied through line 24 and valve 25 and are transported, principally by the gas-lift action of the oxidizing gas, to the lower portion of the first stage regenerator 26.
The regenerator 26 is a Vessel similar in construction to reactor Il, having a substantially cylindrical shell, a substantially cone-shaped `lower head and an upper head in which the cyclone separator 21 is mounted. A suitable per- `orate plate or g'rid 28 for substantially uniformly distributing the incoming catalyst particles and oxidizing gas is also provided in the regenerator.
The condition of the bed of catalyst undergoing regeneration in regenerator 26 is similar to that of the catalyst bed in the reactor, in the sense that the catalyst particles are uidized by the upwardly moving streamy of oxidizing gas and resulting combustion gases with hindered settling of the catalyst particles which gives a catalyst particle concentration in the fluid-like bed greater than that in the incoming stream of oxidizng gas. The approximate line of demarkation be-` tween the relatively dense fluid-like catalyst bed and the upper light phase in which hindered settling of the catalyst particles and their concentration is greatly reduced, is indicated at 29. Substantial burning of the combustible contaminants deposited -on the catalyst particles in reactor Il occurs in regenerator 2-6 by their contact with the air or other oxidizing gas employed for regeneration. Resulting combustion gases and entrained catalyst particles are directed from the light `phase in the upper portion of regenerator 26 to the cyclone separator 21 wherein at least a major ator 26, relative to the rate at which contaminated catalyst is supplied to this zone and the quantity of combustible deposits on the catalyst, is regulated to give a burning Irate 4in the regenerator which will remove a relatively high percentage of the combustible deposits from the catalyst. Actually complete regeneration or complete removal of the combustible deposits is not and can- `not be accomplished in the iluid bed of regenerator 26 for the reasons previously explained and `even a close approach to complete removal is impractical in an operation of the type conducted in regenerator 26. Consequently, the stream of partly regenerated catalyst particles Withdrawn from the fluid bed in regenerator 26 is supplied through transfer line 33, in the case illustrated, to
-a second stage regenerator 34 in which further regeneration of the catalyst to the degree of completion desired is accomplished as the catalyst passes therethrough in the form of a relatively compact downwardly moving mass or bed, the approximate upper extremity of which is indicated at 35. l
The second stage regenerator 34 is also a vertically disposed substantially cylindrical vessel with a substantially cone-shaped lower head and an upper head in which suitable catalyst separating equipment, such as the cyclone separator 36, may be mounted when such equipment is required. Air or other oxidizing gas for continuing regeneration of the catalyst in chamber 34 is supplied, in the case illustrated, through line 31 and valve 38 into a suitable distributing member 39, which, in this particular instance, has substantially conical upper and lower sections, the upper cone being perforated or in the form of a suitable screen or grid for distributing the incoming oxidizing gas substantially uniformly across the catalyst bed.
Due to the relatively small amount of combustible contaminants remaining on the catalyst being supplied to regenerator 34, the quantity of air or other oxidizing gas required to carry the regeneration to the desired degree of completion will be relatively small in relation to that supplied to regenerator 26. Consequently, the second stage regenerator 34 can normally be a chamber of relatively small diameter in relation to that of regenerator 26 and still maintain a suciently low linear velocity for the ascending oxidizing gas and resulting combustion gases in chamber 34 to preclude a degree of fluidization which will give pronounced hindered settling and turbulence in the catalyst bed.
It will, of course, be understood that there are varying degrees of uidization and hindered settling, ranging all the way from a condition at which there is no upward movement of the catalyst particles within the bed to the opposite extreme atvwhich the gas velocity is so high that the catalyst particles are carried upwardly therewith through the vessel with no appreciable downward movement of the catalyst particles. The uidized condition of the bed of catalyst or con- -tact material in the rst regenerating stage of the process herein provided is well within these two limits, the object being to obtain a degree of hindered settling or back flow of catalyst particles which will result in .thorough mixing and Asufficient turbulence inthe catalyst bed to give a i substantially uniform temperature distribution throughout the latter. This is the condition implied by the terms fluid bed, fluid-like state" and similar expressions used herein.v The condition of the bed of catalyst or contact material in the nal regenerating step-of the process is preferably at or near the lower end of the range above mentioned, the object being to preclude a degree of turbulence and hindered settling which would result in such thorough mixing of the catalyst particles that there is little or no gradation in their degree of contamination or state of regenl eration in different portions of the bed. This is the condition implied by the terms compact bed,
relatively compact state and similar expressions used herein. It does not necessarily imply that there is only downward movement of catalyst particles within the bed and preferably, with countercurrent ow of catalyst and oxidizing gas in this step, the velocity of the latter is suicient to maintain a limited amount of suspension or upward movement of catalyst particles' to prevent a degree of compaction which would hinder or stop substantially uniform general downward movement of the bed.` In other words, the compact bed is aerated su'iciently'to prevent excessive compaction.
The air or other oxidizing gas passes upwardly through the relatively compact bed of catalyst particles in regenerator 34, burning all or a substantial portion of the 'remaining combustible deposits therefrom, but due to the relatively lowI percent of combustibles on the incoming catalyst particles, the burning rate is suiliciently low that excessively high temperatures are not developed in this step. 1
Combustion gases leaving the upper portion of y the compact bed in regenerator 34 are discharged illustrated, to which combustion gases from the rst stage regenerator are supplied, or elsewhere as desired.
Regenerated catalyst passes around the distributing member 39 in regenerator 34 to standpipe 44 through which it is directed downwardly and through a suitable adjustable orifice or flow control valve 45 at its lower end into transfer line I6 to commingle with the incoming stream of iluid reactants in which the regenerated catalyst is transported, as previously explained, to reactor l I.
To substantially strip the 'column of catalyst particles passing downwardly through standpipe 2| of reactants and fluid conversion products, steam or other suitable -relatively inert gas is supplied to this line in regulated relatively small .i amounts on the upstream side of valve 22 at one or a plurality of points. Line 46 and Valve 41 are provided for this purpose, in the case illustrated. Similarly, steam or other relatively inert gas is supplied to standpipe 44 on the upstream side of valve 45 at one or a plurality of points to substantially strip the column of catalyst particles passing through this line of oxidizing gas and combustion gases. Line 48 and valve 49 are provided, in the case illustrated, for this purpose. It is, of course, within the scope of the invention to employ a flow control valve or the like in line 33 and to introduce stripping gas on the upstream side of this valve. However, since the ow of catalyst through the second stagel regenerator 34 can be controlled by the adjustable orifice or flow control valve 45 in standpipe 44, and since the transfer of a relatively small amount of oxidizing and combustion gases from the regenerator 26 to the regenerator regenerator may be controlled by controlling the catalysteirculation rate through line 62, cooler 63 and line 54, in which case a suitable adjustable orii'lce or flow control valve 55 is provided v inthe latter. Alternatively, circulation through this line may be maintained at a relatively constant rate and control of the temperature in regenerator 26 accomplished by controlling the temperature and the rate at which water, steam, relatively cool oil or other suitable cooling medium is passed through the catalyst cooler 53. In the case illustrated, the cooling medium is supplied ythrough line 56 and is discharged at the'desired higher temperature through line 51, controlled by valve 58.
Figure 2 illustrates a slight modication ofthe arrangement shown in Figure l, corresponding portions of the apparatus in the two figures `being `designated by the same reference numerals. With the arrangement shown in Figure 2, the separator 36, which serves the second stage regenerator of .Figure 1, is eliminated and outgoing combustion gases from the second stageA regenerator are directed from the space above the relatively compact catalyst bed 35' therein through line 50 to the light phase in the rst stage regenerator 26. This arrangement may be employed in case the two regenerators are operated at substantially the same pressure or in case a slightly higher pressure is employed in regenerator 34` and when a suiiicient quantity of catalyst particles is entrained in the outgoing combustion gas stream from the second stage regenerator that it is desirable to employ a separator. In such instances, separator 21 will serve the outgoing combustion gases from both stages of the regeneration. When desired, instead of connecting line 50 with the upper portion 'of the regenerating vessel 26, it may communicate directly with separator 21. In case higher pressure is employed in the upper portion of regenerator 34 than that prevailing in the upper portion of regenerator 26, a suitable pressure control valve-5I is interposed in line 50.
Another alternative arrangement, contemplated outgoing combustion gases, as well as partially regenerated catalyst from the first stage to the 34 through line 33 is not objectionable, a ilow,
control valve and stripping means in this line can ordinarily be eliminated andiare not illustrated in the drawings.
The invention contemplates the use of external cooling of the catalyst, when required, to control the temperature in the rst stage regenerator and this may be accomplished, for. example, by withdrawing a stream of catalyst from the dense phase iluid bed in this zone through line 52, passing the same through a catalyst cooler 53, which may be a wasteheat boiler or other suitable type of heat exchanger, from which the cooled catalyst is supplied through line 54 to the lower portion of the regenerating vessel 26. Alternately, when desired, the cooled catalyst may be i'ntroduced into the transfer line 23 to commingle with the incoming catalyst from reactor I I.
second stage regenerator, in which case separator 21 may be eliminated and a sufiiciently large separator 36 is employed on the second stage regenerator 34 to serve combustion gases from both stages. desirable in case regenerator 26 is operated at a higher pressure than regenerator 34. Suitable provisions for accomplishing this modification will be apparent andl are not illustrated. The combustion gases from chamber 26 may be supplied to the upper portion of chamber A34 or directly to separator 36, together with or separate from the partly regenerated catalyst being supplied from the iirst to .the second stage regeneration. i
Referring now to Figure 3, showing a modied arrangement of apparatus suitable for conducting the process of theinvention and a different method and means of effecting circulation ofthe catalyst through the reaction and regenerating operation, the reactor is indicated at 60, the first stage regenerator at 6| and the second stage regenerator at 62.
Regeneration of the contaminated catalyst from reactor 60. to the desired degree is .accom-l the bed of catalyst being maintained in a tur- This arrangement is particularly bulent uuid-like state in this zone, with hindered settling ol the catalyst particles, and air or other oxidizing gas for regeneration being supplied to the lower portion of regenerator 6| through line 64 and valve 65. Catalyst is separately supplied to the lower portion of regenerator'6l through line 66, as will be' later described, and the l oxidizing gas and incoming catalyst are subsection of the cylindrical portion of the vessel by means of a perforate plate or other suitable form of distributing grid indicated at 61.
The principal difference between the iirst stage regeneration as accomplished in vessel 26 of Figure 2 and in vessel 6| of Figure 3 is that,
` stantially uniformly distributed-over the crossl due to the diierent method of transporting the catalyst from this zone to the second stage re generator, there will ordinarily be no delinite and relatively sharp line of demarkation between the fluid-like'catalyst bed in regenerator 6| and a light, phase in the upper portion of the regenerator. Stated another way, the light phase in regenerator 6| has a considerably higher solid particle concentration than in regenerator 26, or the dense phase level is higher, occurring at approximately the juncture of the upper head 68 of vessel 6| withtransfer line 69 'or somewhere within head 68. However, there is a considerable gradaticn of catalyst particle concentration from the lower to thev upper extremity of the fluid-like bed, the concentration progressively diminishing at higher points in the bed.
Instead of transporting the catalyst from the rst stage to the second stage regenerator as a relatively compact stream, it is transported by the gas-lift action of the outgoing combustion gases through the substantially straight vertical transfer line 69 from the upper portion of regenerator 6| into the upper portion of regenerator 62. The enlarged upper section 1|) of the latter vessel causes a suilicient reduction in the velocity of the gas leaving transfer line 69 that atleast a substantial portion of the catalyst particles are separated therefrom in this zone by settling. The catalyst passes downward through the smaller lower portion 1| of the second stage regenerator as a relativelyl compact mass or bed countercurrent to the air or other oxidizing gas supplied thereto through line 12, valve 13 and a suitable distributing member 14. Preferably; a
` `suitable deector 15 is provided above the open upperend of ltransfer line 69 within vessel 62 and, when desired, suitable varies, not illustrated, may be provided between the upper extremity of transfer line 69 and member 15 for imparting a centrifugal motion to the gases and catalyst particles leaving line 69 so as to assist separation of the catalyst particles. Combustion gases, including those formed in the second stage regenerator and those supplied to this zone from the rst stage regenerator, are directed with entrained catalyst particles through line 16 to suitable catalyst separating equipment, summeyclene-Separator indicated at 11, wherefrom separated catalyst particles are directed through line 18 into the downwardly moving catalyst bed in regenerator 62, while the gases are directed from the upper portion of the separator through line 19 and -valve 86, preferably to suitable heat recovery equipment not illustrated.
portion of regenerator 62 through transfer line vcontrol-the regenerating temperature, a regulated` I portion of the total quantity of catalyst dis-LJ charged from the lower portion of regenerator 62 is diverted from line 8| through line 83 to the catalyst cooler 93 which may be any suitable form of waste-heat boiler, heat exchanger or the like capable of cooling the required quantity of catalyst to the desired temperature. From cooler 93 a portion or al1 of the cooled catalyst is directed through line 84 and the flow control valve 85 adjacent its lower end into the catalyst transfer line 66, to pass with the catalyst from the reactor into the lower portion of chamber 6|, or it may be supplied directly to the latter zone, when desired. This will accomplish the same sort of temperature control in`the first stage regenerator as is accomplishedby the catalyst circuit through cooler 53 in Figure 1.
In addition, provision is made, in the case illustrated in Figure 3, for separately controlling ,the top temperature in the iirst stage regenerator and therebycontrolling the temperature of the catalyst entering the second stage regenerator, independent of the average temperature employed in the first stage.` To do this regulated quantities of the cooled catalyst from cooler 93 are directed as a relatively compact stream or ,column through line 86 and the flow control valve 81 into the upper portion of the first stage regenerator to commingle therein with the catalyst about to b e transported through transfer line 69 to the second stage regenerator. Alternatively, cooled catalyst from cooler 93 maybe supplied directly into line 69, but I ordinarily prefer to introduce it into the upper portion of chamber 6| since the top temperature in the rst stage regenerator may thus be maintained suiiiciently low to preclude oxidation or burning of carbon monoxide in the upper portion of chambers 6| and 62 and thus prevent the development of excessive temperatures in these zones.
By controlling the temperature of the ,catalyst entering they second stage regenerator, as above y oxidizing gas supplied to the second stage rey generator is preferably much smaller than the quantity supplied to the rst stage regenerator 'and a major portion of the total regeneration is accomplished in the rst stage regenerator where the catalyst bed is in a' turbulent fluid-like condition.
With the arrangement illustrated in Figure 3, the conversion reaction may be accomplished in reactor 60 with the catalyst bed in either a uidlike or a relatively compact condition in this zone. The hydrocarbon to be cracked or any other uid reactants to be converted is supplied either in relatively cold or in preheated state and at or below the desired reaction temperature through line 88 and valve 89 to the inlet compartment 9|) in the lowerportion of reactor 60. They are then directed through the substantially coneshaped perforate member or distributing grid 9| into the catalyst bed, wherein they are converted in the presence of a catalyst and wherefrom the resulting iiuid conversion products are directed into a substantially catalyst-free space or relatively light phase in the upper portion of the.
tion in the catalyst bed and it is within the scope l of the invention to operate the reaction zone with any desired degree of turbulence and hindered settling in the catalyst bed or with little or no upward movement of the catalyst particles in the bed.
Fluid conversion products are directed from the reaction step through line 94 and valve 95, preferably to s uitable further fractionating, separating and recovery equipment, not illustrated, and in case the stream of fluid conversion products leaving the relatively dense catalyst bed in the reactor contains a substantial quantity of catalyst particles, suitable separating equipment, such as the cyclone separator 96, is provided for their substantial removal. Catalyst separated from the outgoing fluid conversion products in separator 96 is returned through line 91 to the relatively dense phase or compact bed in the reactor.
The catalyst particles of the bed in reactor 60 move outwardly and downwardly, around the inlet zone 90 for the uid reactants, and are directed by the substantially cone-shaped bottom head of the reactor into transfer line 66`through which the contaminated catalyst passes as a relatively compact stream or column to the rst stage regenerator. A suitable adjustable orifice or iiow control valve 98 is preferably provided in line 66 on the upstream side of its junction with line 84.
To substantially strip the stream of catalyst particles passing from reactor 60 to regenerator 6| of reactants and fluid conversion` products, a suitable stripping gas, such as steam, for example, is supplied to line 66 on theupstream side of valve 98 in regulated amounts and at' one or more points in this line. Line 99 and concurrent downward flow of reactants, resulting conversion products and catalyst in a. relatively compact moving catalyst bed. The construction of reactor ||0 of Figure 4, as here illustrated, is similar to that of reactor 60 of Figure 3, except that the incoming reactants are supplied through line III and valve |I2 to the upper portion of the reaction vessel and into the space `above the compact downwardly moving catalyst bed ||3, while resulting fluid conversion products are directed from the lower portion of the bed through a suitable perforate member or screen |I4 into the outlet compartment IIS, from which they are discharged. through line ||6 and valve 1.
The cyclone separator at the upper end of the reactor is eliminated in Figure 4, but in case relatively flne catalyst particles are carried through member I I4 in the outgoing stream of conversion products, a cyclone' separator or other suitable separating equipment may be provided' within the outlet compartment I I5 or may be interposed in line ||6. Separated catalyst from this equipment may be returned to the transfer line I'I9 leading from the lower end of reactor ||0 to the regenerating equipment.v
Regenerated catalyst is supplied, in the vrcase illustrated in Figure 4, through line ||8 to the upper portion of reactor ||0 and, in case an arrangement otherwise similar to that illustrated in Figure 1 is employed with a down-flow reactor like that of Figure 4, it is within the scope of the invention to transport the regenerated catalyst into the upper portion of the reactor with all or a'portion of the incoming iluid reactants through line IIB.
By employing a compact, downwardly moving bed of catalyst particles in the reaction zone and passing the reactants and resulting fluid convervalve |00 are provided for this purpose in the case illustrated. Similarly steam or other suitable relatively inert gas is supplied to linev 8| on the upstream side of valve 82 for the purpose of substantially stripping the stream of catalyst passing from regenerator 62 to reactor 60 of oxidizi'ng gas and combustion gases. Line I0| and valve |02 are provided in the case illustrated for the introduction of regulated amounts of stripping gas into line 8|. Stripping of the catalyst in the cooling circuit through cooler 93 will not be necessary, but it is desirable to prevent excessive compaction of the catalyst in lines 83, 84, 86 and cooler 93. Therefore, in the case illustrated, line |03 and valve |04, communicating with line 04 1 on the upstream side of valve 85, and line |05 and valve |06, communicating with line 86 on the upstream side of valve 81, are provided for the` introduction of a sufcient quantity of steam, other relatively inert gas or oxidizing gas into these lines to flow upwardly therethrough couny .tercurrent to the descending catalyst columns and prevent a degree of compaction which might hinder or stop the flow of catalyst therethrough.v
The reactor I I0 illustrated in Figure 4 is a modified form of reactor which may be employed within the scope of the invention to obtain thel plate.
sion products downwardly through the bed in the general manner illustrated in Figure 4, higher linear velocities for the fluid reactants and con-A version products may be employed, as compared v stages of regeneration are accomplished in a single regenerating vessel indicated at |20 and constructed, as illustrated, with a substantially cylindrical outer shell |2I, a substantially coneshaped head |22 at the lower end of shell |2| and an upper head |23, in which a suitable cooler |24 is mounted. First stage regeneration is accomplished in a iluid-like catalyst bed |25 disposed within the annular space defined between v the cylindrical shell I2I and the inner cylindrical wall |21. Wall |21 denes a space within which second stage regeneration is accomplished with the catalyst bed in a relatively compact condition as indicated at |26. In this instance, the inner compartment containing bed |26 terminates in an enlarged section |20'disposed beneath headv |22 and having substantially conical upper and lower sections. Section |28 contains an inner compartment |29 also formed by substantially conical upper and lower sections, the upper member |30 comprising a suitable screen or perforate A suitable perforate plate or distributing grid |3I is disposed adjacent the lower end oi' the annular space between members |2I and |21.
The catalyst from the reaction zone, not illustrated in this figure, is transported in the case illustrated in a stream of incoming air or other oxidizing gas for regeneration through line |32 into the space` between the substantial conical member |22 and the cylindrical member |21, preferably entering this space tangentially. The oxidizing gas and catalyst pass upward through the distributing grid |3| and a substantial portion of the combustible contaminants are burned from the catalyst in the turbulent fluid-like bed |25. Catalyst spills over from the iluid bed at the upper extremity of member |21 into the space defined by the latter and forms the downwardly moving catalyst bed |26, wherein regeneration is carried to the desired degree of completion.
The second stage regeneration in this instance is similar to that previously described in conjunction with the other gures of the drawings in that it is conducted with the catalyst particles in the form of a relatively compact downwardly moving bed but differs therefrom in that it is accomplished with a mixture of air diluted with combustion gases from the first stage regeneration, preferably after said combustion gases have.
been cooled, and the oxidizing gas stream ilows downwardly rather than upwardly through the compact bed. By diluting air for the second stage combustion with cooled combustion gases from the first stage, more heat may be carried from the second stage regeneration in the outgoing combustion gases to prevent the development of excessive temperature in this Zone. This necessitates the use of higher gas velocities in a second stage zone of given cross-sectional area and, by passing regenerating gas downwardly through the compact bed in the second stage,'
relatively high linear velocities can be used without obtaining uidization and turbulence in the l bed.
' The temperature of the gases in the light phase of the regenerator above the upper extremity of member |21 is preferably kept considerably below the average temperature in the iiuid bed |25 by the circulation ofl gases from this light phase region through cooler |24 back into the light phase region, the flow through the cooler` being indicated by arrows in the drawings. In this particular instance cooler |24 comprises a tubular type heat exchanger to which low temperature steam, water for the generation of steam or any other suitable cooling medium is supplied in regulated quantities through line |33 and valve |34, and the resulting heated iiuid is discharged through line |35 and valve |36. The temperature of the entering cooling fluid and the rate at which it is passed through the cooler are controlled to give the desired. temperature in the light phase of the regenerator. Although thermal circulation of comrbustion gases through the cooler is illustrated, it will, of course', be understood that forced circulation may be obtained, when desired, by a suitable fan or blower, not illustrated, and when a thus controlled rate of gas circulation is employed it will serve as an additional method of control over the temperature in the light phase.
In case it is not desired to pass all of the comlbustion gases issuing from vthe fluid bed |25 through the compact bed |26, a regulated quantity thereof may be discharged from the light phase through line |31 and valve |38, the latter preferably being a pressure control valve which holds a sumcient operating pressure in the light in the drawings, although it may be supplied at one or any desired number of spaced points in theheight of the compact bed. In the case illustrated, a portion of the required air is supplied in the upper region of or above the compact bed through line |39, valve |40 and a distributing member |4| while another portion is supplied to an intermediate point in the compact bed through line |42, valve |43 anddistributing member |44, and the remaining portion is supplied 20 to a lower intermediate point through line |45,
Ivalve |46 and the distributing member |41.
Combustion gases supplied to the compact bec and those resulting from the combustion of catalyst deposits therein flow through the perforate member |30 into the outlet compartment formed by members |29 and |30 and are discharged preferably to suitable heat recovery equipment, not illustrated, through line |48 and valve |49. When desired, suitable separating equipment for removing any entrained catalyst particles from the outgoing gas stream may be interposed in line |40 and, in case a portion of the combustion gases from the fluid bed are discharged through line |31, the latter preferably leads to the same catalyst separating equipment, although separate cyclone separators or the like may be employed for the two streams, when desired.
Regenerated catalyst in the compact bed passesk downwardly through member |28 about the gas s outlet compartment 129 to a suitable standpipe |50, having an adjustable oriice or ilow control valve |5| adjacent its lower end and through which the regenerated catalyst is directed in regulated quantities back to the reactor, not illustrated, Conveniently, the catalyst from line |50 troduced through line |52 and valve |53 on the upstream side of valve |5|.
A cooling circuit for` maintaining the desired temperature in the fluid bed, similar to that illustrated in Figure 3, may be employed, when des'ired. In the case illustrated, this circuit comprises a line |54 leading from the upper portion of the iluid bed |25 to a suitable cooler |55, such as a waste-heat boiler or other form of heat exchanger communicating through line |56 and the flow control valve |51 with line |32.
I claim: l
1. In a process wherein a mass of subdivided solid particles comprising combustible and substantially non-combustible components is treated to effect the removal of combustibles therefrom,
the improvement which comprises effecting said removal in a sequence of burning steps, in one of which the solid particles are maintained in the form of 'a uid-like mass and in another of 5 which solid particles from said uid-like mass ascq/1o stantially non-combustible components is treated to effect the removal of combustibles therefrom. the improvement which comprises burning a major portion of said combustibles while maintain- `ging the solid particles in the form of a fluid-like mass and subsequently burning at least a portion of the remaining combustibles while maintaining the solid particles in the form of a relatively compact mass. i
3. A process of removing combustible contaminants from substantially non-combustible subdivided solid contact material which comprises maintaining a mass of the solid particles in a fluid-like state and contacting the same with oxidizing gas to burn a substantial portion of the combustible contaminants therefrom and thereafter maintaining a mass of the solid particles from said burning step in a relatively compact condition and contacting the same with oxidizing gas under combustion conditions to burn additional quantities of combustible contaminants therefrom. l I
4. A process such as defined in claim 3, wherein solid particles comprising therespective fluidlike and compact masses are moved continuously through separate confined combustion zones and wherein oxidizing gas and resulting combustion gases arepassed upwardly through the mass in each of said zones. l
5. Aprocess such as defined in claim 3, wherein solid particles comprising the respective fluidlike and compact masses are moved continuously through separate confined combustion zones and wherein oxidizing gas and resulting combustion gases are passed upwardly through the uid-like mass and downwardly through the compact mass.
6. A process such as dened in claim 3, wherein solid particles comprising the respective fluidlikevand compact masses are moved continuously through separate -conned combustion zones and wherein oxidizing gas and resulting combustion gases are passed upwardly through the fluid-like mass and downwardly through the compact mass,l
the gases passing through the compact mass comprising at least a portion of those which have previously passed through the fluid-like mass.'
7. A process such as deilned in claim 3, wherein combustion gases resulting from the burning of combustible deposits in said iluid-like mass are cooled and supplied to said compact mass.
8. A process such as defined in claim 3, wherein combustion gases resulting from the burning of combustible -deposits in said huid-like mass are cooled and supplied to said compact mass and wherein a regulated quantity of fresh oxidizing gas is also supplied to said compact mass.
9. A process such as defined in claim 3, wherein a stream of said contact material is removed from at least one of said masses, cooled and returned thereto to assist in controlling `the temperature to which the contact material is sub' .iected therein. 'Y
10. In the regeneration of subdivided solid catalyst which is substantially non-combustible but susceptible to damage by overheating and which is contaminated with combustible deposits, the steps which comprise continuously supplying a stream of the contaminated catalyst particles to a combustion zone, therein maintaining a uidlike mass of the solid particles and burning a maior portion of the combustible contaminants therefrom by passing oxidizing gas upwardly .through said mass, continuously supplying a Y stream of resulting partially regenerated catalyst from said combustion zone to a separate combus- ,tion zone, passing the solid particles through the last named zone in the form of a relativelycompact mass, burning at least a substantial portion of the remaining combustible contaminants from the catalyst particles in the last named zone by passing oxidizing gas through said moving relatively compact mass, continuously discharging a stream of resulting hot regenerated catalyst particles from said compact mass, cooling a portion of the catalyst particles thus discharged and returning resulting cooled regenerated catalysty to said fluid-like mass in the rst named combustion zone at a temperature and rate correlated to limit the temperature attained by the catalyst in the latter zone and prevent damage thereto by overheating and likewise limit the temperature of the stream of catalyst particles being supplied from the rst named to the second named combustion zone.
l1. In the regeneration of subdivided solid catalyst which is substantially non-combustible but susceptible to damage by overheating and which is contaminated with combustible deposits, the steps which comprise continuously supplying a stream'of the contaminated catalyst particles to.
a combustion zone, therein maintaining a fluidlike mass of the solid particles and' burning a major portion of the combustible contaminants therefrom by passing oxidizing gas upwardly through said mass, continuously supplying a stream of resulting partially regenerated catalyst from said combustion zone to a separate combustion zone, passing the solid particles through the last named zone in the form of a relatively compact mass, burning at least a substantial portion of the remaining combustible contaminants from the catalyst particles in the last named zone by passing oxidizing gas through said moving relatively compact mass, continuously discharging a stream of resulting hot regenerated catalyst particles from said compact mass, cooling a portion of the catalyst particles thus discharged, returning resulting cooled regenerated catalyst to said fluid-like mass in the rst named combustion zone at a temperature and ratecorrelatedo limit the temperature attained by the catalyst in the latter zone and prevent damage thereto by over-heating, and returning another portion of the cooled regenerated catalyst tothe second named combustion zone to further reduce the temperature attained by the catalyst therein independent of that attained by the catalyst in the first named combustion zone.
regulated to maintain' the'mass in a fluid-like A condition, thereafter burning additional combustible contaminants from the resultant partially regenerated catalyst particles lwhile maintaining the same in the form of a relatively compact mass and while passing oxiding gas through the latter and subsequently employing resulting hot regenerated catalyst to'promote said endothermic conversion reaction.
13. The process defined in claim 12, wherein said conversion reaction comprises catalytic cracking of ,the hydrocarbons and the subdivided solid catalyst comprises a siliceous cracking cata-` lyst.
14. The process defined in claim 12, wherein said conversion reaction comprises catalytic dehydrogenation of the hydrocarbons and the subdivided solidl catalyst comprises a dehydrogenating catalyst containing alumina and at least one other metal oxide.
15. The process dened in claim 12. wherein said conversion reaction comprises catalytic aromatization o! the hydrocarbons and the subdivided solid catalyst comprises an aromatizing catalyst containing alumina and at least one other metal oxide.
16. A process for regenerating subdivided solid catalyst containing carbonaceous deposits which comprisesburning a substantial portion of the carbonaceous matter from the catalyst while passing an oxidizing gas upwardly through a bed of the catalyst at a rate suilicient to'maintain said bed in a iluldized condition, removing par-- tially regenerated catalyst from the uidized bed and maintaining a relatively compact mass thereof at combustion temperature, and passing oxidizing gas through said relatively compact mass to burn additional carbonaceous, matter from the temperature and burning additional carbonaceous matter therefrom by passing oxidizing gas through said mass, and continuously transferring partially regenerated catalyst from the fluidized bed to the top ci said mass and withdrawing regenerated catalyst from the bottom of said mass to effect a downward movement of catalyst particles within the relatively compact mass.