US2419088A - Process for contacting reactants with catalytic material - Google Patents

Description

April 15, 1947. p PUTNEY 2,419,088

PROCESS FOR CONTACTING REACTANTS WITH CATALYTIC IATERIAL Original]. Filed Dec. 8, 1944 2 Sheet-Sheet 1 a .mm

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Original Filed bee. a, 1944 2 Sheets-Sheet 2 Patented Apr. 15, 1947 UNITED- STATES PATENT OFFEE PROCESS FOR CONTACTING REACTANTS WITH CATALYTIC MATERIAL David H. Putney, Kansas City, Mo., assignor to Stratiord Development Corporation, Kansas City, Mo., a corporation oi Delaware Original applicationDecember 8, 1944, Serial No. 567,240. Divided and this application Jami ary 17, 1947, Serial No. 722,738

3 Claims. (Cl. 196-52) invention will be described with regard to this application.

This application is a division of Serial No. 567,240 filed December 8, 1944, which application was a continuation-in-part of Serial No. 558,251 filed October 11, 1944. e

In the co-pending application, Serial No. 558,251, there is disclosed a contacting apparatus or a similar nature. The construction there shown is identical with that contemplated here except that there was omitted from the prior application the stationary vanes within the circulating tubes of the reactor and regenerator and straightening vanes in the passageway between the dow'nfiowing and upflowing columns in the bottom of the vessels. While the construction shown in the prior application provides an effective means of contacting the catalyst and reactants, experimental tests have proved that increased efilciency and better results are accomplished where the straightening vanes are used, The primary purpose of these stationary vanes is to limit and, to a. great extent, prevent the effects of centrifugal force originating in the rotating impellers f'romtaking precedent and seriously interrupting the straight line or lineal Another object is to provide straightening vanes which have their upper portions vertical thus preventing any tendency of the mixture to vortex or prerotate before entering the impellers above them.

The straightening vanes in the passageways between the downflowing and upflowing columns provide'straight surfaces parallel with the flow oi the material and prevent prerotation or vortexing oi the mixture oi catalyst and reactants entering the upflowing column and flowing stream in which the impellers are located. Other and further objects will appear from the following description.

In the accompanying drawings which iorm a part of the instant specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like'parts in the variousviews,

Fig. 1 is a sectional elevational view of a reactor and regenerator designed for the cracking of hydrocarbons in the presence of a solid pulverulent catalyst,

flow oi the materials in the circulating rings which are set up and maintained in the respective vessels.

In other words, the salient object of the invention is to provide an apparatus for preventing the rotation or spinning of the flowingmixture of catalyst and reactants in the cycles established in the reactor and regenerator.

Another obiect oi the invention is to provide a design wherein the straightening vanes are pitched on the side adjacent to the impeller discharge to approximately the same angle as the and the lighter vapor to the inside resulting in separation of the catalyst irom the vapor.

Fig. 2 is a view taken along the line 2-2 in 25 Fig. 1 in the direction of the arrows,

Fig. 3 is a view taken along the line 3-3 in Fig.1 in the direction 01' the arrows,

Fig. 4 is a view taken along the line 4-4 in Fig. 2 in the direction oivthe arrows,

Fig. 5 is a view taken along the line 5-5 in Fig. 1 in the direction of the arrows,

Fig. 6 is an enlarged detail of the lower end of the heat exchange tubes employed in the re-. generator for removing heat,

Fig. '7 is a view taken along the line 1-4 in Fig. 1 in the direction of the arrows,-and

Fig. 8 is a View taken along the line 8-4 in Fig. 1 in the direction of the arrows.

Reierring to the drawings, the smaller vessel shown in Fig. 1 is the reactor. and the larger vessel the regenerator. The construction and design of the two vessels is substantially identical so that a brief explanation of one will sumce for both. The design includes an upright cylindrical vessel having an open-ended'circulating tube positioned centrally oi the vessel and extending to a level about one-half its height. The circulating tube has a common axis with the vessel. Extending the length of the vessel and centrally thereof is a shaft rotated either from above or below by a suitable prime mover and mounted on the shaft and within the circulating tube is a plurality of impellers which produce a cyclic flow of catalyst in an upfiowlng column within the circulating tube and a dcwnflowing colmrm in the annular space between the circulating tube and the shell ofthe vessel. Catalyst is trans ierr'ed irom the upper portion of the downflowing column-oi the respective vessels tn the lower portion 01 the downflowing column of the other 3. vessel. Reactants are introduced into the bottom of the upflowing column of each vessel and, after separation from the catalyst in the upper the sleeve 20. In the bell-shaped lower portion part of the vessel, are removed from 'the top.

Thus, it is seen that there is established within both the reactor and regenerator flowing streams of catalyst in the form of cyclic rings, each ring having an upilowing column and a clownflowing column. The flow of the catalyst in the rings is initiated and maintained by mechanical devices, such as rotating impellers, producing positive circulation and intimate mixture of the reactants and catalyst flowing through the vessels.

Referring to Fig. 1, the shells of both the reactor and regenerator are designated by the numeral l0. Each-has a head H and a bottom' l2. Within the vessel are open-ended circulating tubes [3 to which are attached stationary. radial straightening vanes l4. Mounted on the top of the vessels on pedestals l5 are prime movers I6 which are shown in the drawings as electric motors. Through shafts I! the motors drive the 'vertical propeller shafts 18 which extend longitudinally of the vessels and have suitable upper and lower bearings which are cooled in order that they are operated within the proper temperature range. Outside the shaft and rigidly connected thereto by annular supports l9 are sleeves 20 upon which are mounted the impeller blades 2 I. These impeller blades are positioned within the annular tubes and are pitched and rotated, as shown in Fig. 5, to move the solid material within the circulating tubes upwardly. Pulverized catalyst is supplied to the regenerator from any convenient iii are started to rotate the impellers 21-. The circulating stream or ring of catalyst is established in the regenerator flowing upwardly through the circulating tube and downwardly through the an-.

nular space outside the tube. Catalyst overflowing the top of the circulating tube in the regenerator passes through transfer pipe 23 to the reactor where it is picked up by the impellers and a similar cyclic ring established in this. vessel. In a like manner a portion of the catalyst overflowing the top of the circulating tube in the reactor is returned through transfer pipe 25 to the bottom of the regenerator. The levelsv of the catalysts in the vessels is determined by a level float arrangement shown diagrammatically at 25. when sufficient catalyst has been admitted to the vessels to provide an adequate amount of catalyst for the two cyclic rings and the temperature of the vessels raised to proper operating conditions reactants in vapor form are introduced into the bottom of the reactor through pipe 26. In the reactor the catalyst and reactants are intimately mixed as the pass upwardly through the upfiowing column of the catalyst ring. In this column the impellers agitate the catalyst and disperse the reactants through the catalyst. Canes l4 positioned between the impeller blades prevent rotation of the upflowing column and keep the flow of catalyst in a relatively straight v line. At the top of the circulating tube t3 the flow of the catalyst is reversed separating the solid particles from the reactants which rise into the vapor space in the upper part of the reactor. Inevitably there is entrained a portion of reactants which are circulated back with the catalyst into the downfiowing column of the ring. Positioned in the vapor space of both vessels is a catalyst separator in the form of an inverted funnel 277 which, is attached to and rotates with source not shown through pipe 22 and the motors of the catalyst-separators are radial vanes 27a which contact the solid particles entrained with the vapors and by centrifugal force project them outwardly through apertures in the periphery of the separator into a downfiowing stream created at the outer edge of the separator by downpumping. vanes 21b between the periphery of the separator and a ring 210 which surrounds the separator and rotates with it. After separation of the entrained catalyst the vapors rise through the top of the separator and are discharged from the reactor through pipe 28. The cracked product passing ofi from the top of the reactor is directed to conventional fractionation and recovery equipment not shown.

Returning to the travel of the catalyst, after overflowing the top of the circulating tube it flows into the annular. space between the circulating tube and shell in a downfiowing column. A portion of the catalyst overflowing the top of the circulating tube passes into the transfer pipe 24 and is directed to the regenerator. The rest of the catalyst in the downflowing column after passing the straightening circulation tube supports 29 and 30 positioned in the annular space has its direction reversed in the bottom of the shell." Recycled catalyst returned through the downfiowing column and catalyst transferred from the regenerator through pipe 23 is drawn into the bottom of the circulating tube by the rotation of the impellers and is again mixed with the reactants in the upflowing column. In the bottom heads and beneath the lower impellers are stationary straightening vanes 3|. These vanes 3| extend radially from the central support of the rotating shaft and are positioned in the throat or lower end of the circulating tube. The effect of these straightening vanes It and 3| is to eliminate in so far as possible rotating tendencies of the catalyst mass and to cause the mass to move through the circulating tube and annular space surrounding the tube in a straight line flow.

Catalyst in the regenerator is circulated in the same manner as is the catalyst in the reactor. Air is added to the bottom of the regenerator through pipe 32 to furnish a combustion supporting gas. Air is introduced to the regenerator and gas oil vapor to the reactor through pipes 33 behind baflies 34 to prevent accumulation of catalyst in stagnant portions of thelower heads of the vessels and to facilitate circulation. Air is introduced through pipe 35 in the regenerator to supply a combustion supporting gas to the annular space surrounding the circulation tube and steam is introduced at a similar location through pipe 36 'in the reactor to strip or aerate the downfiowing column of entrained reactants. Steam is introduced to transfer ducts 23 and 24 through pipes 31 to strip the catalyst passing through the ducts of entrained vapors or combustible gases. Dampers 23a and 24a in the ducts 23 and 26 respectively control the amount of catalyst permitted to pass through the ducts to the respective vessels.

Between the shafts l8 and the rotating sleeves 20 is a stationary barrier tube 38 which extends well above the level of the catalyst in the vessels and prevents catalyst particles working up into the sleeve 20 from below and accumulating around the shaft. The vapor supplied to the reactor through pipe 26 and air supplied to the regenerator through pipe 32 passes into the annular space between the shafts and barrier tubes producing an upward flow of gaseous material through these inner ducts and a downward flow through the outer ducts between the barrier tube and sleeve 20. Thus, there is a discharge of gaseous material from the lower ends of the tubes 28 which prevents the admission of catalyst.

To reduce the temperature of the catalyst in the regenerator a coolant is supplied through pipes 39 to the bayonet-type heat exchange tubes ii arranged at intervals in the annular passageway. The coolant flows downwardly through the inner tubes 40, as shown in Fig. 6, and upwardly through outer tubes ii to be discharged through outlet pipes 42. Any satisfactory coolant such as water, oil or other liquid may be circulated through the heat exchangers and thus lower the temperature of the catalyst circulating in the regenerator This cooling system is necessary to prevent excessive heating of the catalyst.

Circulation of the catalyst in the regenerator is similar to that in the reactor. At the top of the circulating tube the combustion gases separate from the solid particles and entrained erence to other features and subcombinaticns.

This is contemplated by and is within the scope of the claims. Having thus described my invention, I claim:

1. In a procedure of catalyst circulation and separation for processes in which gaseous materials are reacted in the presence of a solid catalyst, the catalyst regenerated, the regenerated particles are removed by contact with the vanes 27a of the rotating separator 21. After the solid particles are removed the combustion gases pass out through the openings in the top of the separator and are discharged through flue gas pipe 28a which serves as a discharge for the combustion gases as the pipe 28 did for the cracked products removed from the reactor. Upon discharge from the regenerator the gases are passed to conventional waste heat recovery systems and either recycled or directed to a stack.

As previously indicated, the invention has been described as applied to a fluid catalyst process for cracking hydrocarbon oils. This application was selected as a pilot plant for this purpose-is about to be constructed. Other applications are as feasible and will produce as good results; the feature of novelty residing in the mechanical features of the apparatus rather than the particular application to which the invention is used. In other words, wherever it is desirable and advantageous to intimately combine reactants with a finely divided solid catalyst the establishment of a circulating ring of catalyst and producing:

the flow through the ring by mechanical impellers is the first essential. Secondly, the avoidance or elimination of the rotative tendency in the catalyst mass by positioning straightening vanes in the line of flow of catalyst completes the concept.

It will be seen that the object of the invention has been accomplished. There has been provided a cyclic ring of finely divided solid catalyst comprising an upfiowing column and a downflowing column. The flow in the ring is produced by mechanical impellers in the upflowing column where the reactants are intimately mixed with the pulverulent catalyst. Straightening vanes in the upflowing column on both sides of the impellers substantially eliminate rotative tendencies in the catalyst mass producing an even, uniform, straight line flow throughout the ring.

From the foregoing it will be seen that the inventionis well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and subcombinations are of utility and may be employed without refcatalyst returned to the reaction step for reuse and the entrained catalyst separated from the gases in both the reactor and regenerator, the improvement which resides in establishing rings of moving catalystin both the reactor and regenerator, said rings having concentric upflowing and downflowing columns contacting reactant gases with the catalyst ring in the reactor and regenerating gases with the catalyst ring in the regenerator, mechanically imparting turbulence and propelling force at spaced intervals to the gas catalyst mixture" along the upflowing colunm, ubjecting the mixtures of catalyst and gases in the respective steps to gravitational separation, thereby separating. a portion of the catalyst from the gases, passing the stream of separated gases containing entrained catalyst upwardly in secondary separation zones, mechanically imparting centrifugal force to said upwardly flowing streams to separate entrained catalyst from said streams and project it to the peripheries of said secondary separation zones, and returning the separated catalyst to the catalyst rings.

2. A procedure as in claim 1 wherein the catalyst projected to the peripheries of the secondary separation zones is positively impelled downwardlycountercurrent to the upwardly rising streams and thereby returned to the catalyst rings.

3. In a procedure of catalyst circulation and separation for processes in which gaseous materials are reacted in the presence of a solid catalyst, the catalyst regenerated, the regenerated catalyst returned to the reaction step for reuse and the entrained catalyst separated from the gases in both the reactor and regenerator, the

improvement which resides in establishing rings of moving catalyst in both the reactor and the regenerator, portions of said rings comprising upwardly moving columns and portions downwardly moving columns, the latter surrounding the former, passing catalyst from the upper portion of the reactor ring tothe bottom of the regenerator ring and catalyst from the upper portion of the regenerator ring to the bottom of the reactor ring, contacting reactant gases with the catalyst ring in the reactor and regenerating gases with the catalyst ring in the regenerator, mechanically imparting turbulence and propelling force at spaced intervals to the gas catalyst mixture along the upflowing columns, subjecting the mixtures of catalyst and gases in the respective steps to gravitational separation thereby separating a portion of the catalyst from the gases, passing the streams of separated gases containing entrained catalyst upwardly in secondary separation zones mechanically imparting centrifugal force to said upwardly flowing streams to separate entrained catalyst from said streams and project it to the peripheries of said secondary separation zones, and returning the separated catalyst to the catalyst rings.

DAVID H. PUTNEY.

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