US 2854156 A
Description (OCR text may contain errors)
Sept. 39, 1958 J. w. PAYNE 2,854,156
HYDROCARBON CONVERSION 2 Sheets-Sheet 1 Filed Nov. 8, 1954 INVENTOR Pqylze BY M 4 l I ATTORNEY Sept. 3@, 1958 J. w. PAYNE HYDROCARBON CONVERSION 2 Sheets-Sheet 2 Filed Nov. 8, 1954 INTER/VH1. PRESSURE C ONTEOL COOL ING- FZ 0/0 COOL/#6 6/75 1N VENTOR Jam fi/ifa yzze BY W M United States Patent HYDROCARBON CONVERSION John W. Payne, Woodbury, N. 1., assignor to Socony= Mobil Oil Company, Inc, a corporation of New York Application November 8, 1954, Serial No. 467,501
2 Claims. (Cl. 214-17) This invention relates to the conversion of hydrocarbons by systems of the type which involve moving beds of granular contact material and more particularly to the use of the contact material to maintain seals between zones of diflerent pressures.
In the cracking of hydrocarbons to produce an increased yield of hydrocarbons boiling in the gasoline range it is customary to employ a continuously moving bed of granular catalyst material. Succeeding portions of this material flow through a reactor in which the conversion of the hydrocarbon material takes place. During this reaction the contact material becomes contaminated and provision is therefore made to deliver the moving bed to a regenerator wherein the contaminants are burned ofr. Succeeding portions of the regenerated contact material are then returned to the reaction or conversion zone.
It is desirable that the hydrocarbon conversion take place under pressure and that the regeneration of the contact material take place at atmospheric pressure. Accordingly, the problem is presented of continuously feeding contact material into a reaction zone while maintaining a positive pressure above atmospheric within that zone. One way to effect the seal is to use valves. These are, however, discontinuous in operation, expensive to install and maintain, and damaging to the contact material. Accordingly, resort has been had to feed legs of granular contact material which are long enough to maintain a head of contact material suflicient to keep the desired pressure level within the reactor. Recently there has been a tendency to resort to higher and higher pressures in the reaction zones and this creates a requirement for longer and longer feed legs in order to maintain the seals with an adequate factor of safety.
In an efiort to overcome this problem, resort has been had to feed legs containing zones of increased cross sectional area along their length. The presence of these zones reduces the length of feed leg required to hold any given pressure. The effect of the wide zone is to increase the staticpressure of the gas being held back while reducing its dynamic pressure. This prevents the gas from reaching a bed disrupting velocity at the top of the bed of contact material. The actual volume of the intermediate zone of increased cross section is, of course, dependent upon the pressure to be held and there must be maintained a suflicient amount of contact material above the plane Where the gas falls below bed disrupting velocity to keep the bed density constant so that flow resistance will be stable. If these conditions are met, it is found that the length of the leg necessary to hold a given pressure may be reduced.
It is an object of this invention further to improve the invention briefly described in the preceding paragraph by still further shortening the length of leg which is required to contain a given pressure. It is proposed according to the present invention to employ a feed leg system having portions of increased cross sectional area ice and to operate these in a cyclic manner with periodic compacting of the contact material to increase its capacity to hold reactor pressures. Other objects and advantages of this invention will be apparent upon consideration of the following detailed description of several embodiments thereof in conjunction with the annexed drawings wherein:
Figure l is a fragmentary view in section showing a preferred form of the present invention in one part of its cycle of operation;
Figure 2 is a view of the apparatus of Figure 1 in another part of its cycle of operation;
Figure 3 is a detailed view in vertical section of a tamping plug designed according to the present invention, one form of driving means therefor also being shown; and
Figure 4 is a view in vertical section of another type of tamping plug according to the present invention with a different type of actuator.
Referring now to Figures 1 and 2, the numeral 10 designates a reactor in which hydrocarbons are treated in the presence of granular contact material flowing continuously as a moving bed through a reaction zone gen- ,erally designated at 11. Above the reaction zone there is a contact material receiving zone 12 which always contains enough contact material to maintain a continuously moving bed in the zone 11. The Zone 12 is supplied with contact material from a hopper 13. The hopper 13 is supplied with contact material from a hopper 14 and the hopper 14 is supplied with contact material from a chute 15. The chute 15 receives contact material from a regenerator not shown and an elevator which raises the contact material from the regeneration to the top of the chute. It is customary to regenerate at atmospheric pressures and accordingly the contact material delivered to and issuing from the chute 15 is at atmospheric pressure. On the other hand, the pressure within the reactor it) is about 15 p. s. i. g. This being the case, it is apparent that if pressure leakage from the reactor 10 is to be avoided, the material in the hoppers 13 and 14 must be of such density as to prevent the escape therethrough of fluids under such pressure as prevail within the reactor.
The foregoing objective is achieved by the using of tamping plugs 16 and 17. It will be noted that the hopper 13 contains an upper cylindrical portion 18 of wide cross section, a tapering frusto conical portion 19, and a narrow slightly tapering portion 29 discharging funnellike into the top zone 12 of the reactor 1%). The hopper 14 is similarly constructed including an upper cylindrical portion 21 of large cross section, an intermediate frusto conical portion 22 and a tapering funnel-like portion of small cross section 23 leading into the top of hopper 13. Tapered plugs 16 and 17 are actuated by solenoid assemblies 24 and 25, respectively, which vertically reciprocate the respective plugs through a relatively short stroke. The effect of a downward stroke of one of the tapered plugs 16 or 17 is to compact the granular material into the narrow portion 2! or 23 respectively.
The hopper 14 is vented to atmosphere by a pipe 26. A pipe 2'7 places the interior of the hopper 18 in communication with a valve 28 which is rotatable to connect the conduit 27 to atmosphere through a pipe 29 or to the reactor 16 through a pipe 30. A sealing gas under pressure is supplied to the reactor through a pipe 31.
The operation of the invention depicted in Figures 1 and 2 is cyclic and hence is best understood by a description of a complete cycle. For purposes of this description, let it be assumed that the zone 12 contains an adequate amount of contact material to maintain the moving bed in the zone 11 until the hopper 13 can be refilled. Under these conditions, which are depicted in to the Figure 1 position to vent the hopper 13 to atmosphere. Hopper'14 is continuously vented to" atmosphere" so that there is noappre'ciable difierence in'pressure' between the" interior of the hoppers 13' and 14 at this stage of the operation. Thelen'gth of the compacted leg of.
contact material in the portion. 20 of the hopper 13 is enough to hold back the pressure within the reactor 10,.
hearing in mind that somewhere in the portion 19 of the hopper 13the' gas velocity' falls' below bed disrupting value and bearing in mind that even at the beginning of the refill of hopper 13 there is sufiic'ient' contact material above the plane wherethe' bed disrupting velocity no longer exists to hold thei contactmaterial' in position.
In Figure 1 the plug'17 is shown in its upper or re-v tract'ed' position so the contact material can and does'flow freely out ofthe hopper and into the hopper 13. When the hopper 13 has been adequately filled the flow, cycle is changed from that shown'in Figure 1 to that shown in Figure 2.
In changing over the first thing that is done is to project the plug 17 downwardly to increase the density of the contact material'in the portion 23 of the hopper 14. Thereafter the valve 28' is moved to the Figure 2 position and the plug 16 is pulled upwardly or retracted to establish a connection between the reactor 10 and the hopper 13; The pressure in the hopper 13 is quickly equalized with that prevailing in the reactor. The plug 16' being withdrawn,the' contact material can and does flow out of the hopper 13 and into the upper'zo'ne 12 of the reactor. While this is happening the pressure drop across the porti'on'23 is" held by exactly'the same phenomenon as was described in connection with the portion 20 in the Figure l position'. The'hopper14can' be filled because its upper empty spaces are at atmosphericpressu're. By thetime the hopper14 is adequately filled, hopper 13 willbe low and the zone 12 will be high. Thereupo'n the operation is again restored to the Figure 1 position for refilling of,
the hopper 13. Repetition of these cycles is continued throughout the operation of the device.
By Way of an example, a uniformly tapered seal leg 5 long (part"2023) with a maximum, diameter of 27.3 and a minimum diameter of 18.6" can be used in catalytic cracking process having a catalyst circulation rate of 350 tons per hour. The bed level in the hopper is never less than 3' (height of part 1922), this being to maintain' an adequate head above the plane where the bed disrupting velocity ceases. In such a hopper, a tapered plug 5 long actuated by a solenoid was'used. The plug tapered from a maximum diameter of 18" at the top to a minimum of 6" at the bottom. The tapered plug forced into the seal leg brought a 10% reduction of bed volume. In order to make the resistance to blowout nearly uniform, it is desirable to use a tapered plug in a tapered leg as shown in Figure}. The most effective taper is an' acute angle theta with the angle phi of theportion 23 greater than zero. In the example shown in Figure 3 theta equals 12 and phi 4. The apex angle of the frusto conical walls of the portion 23 of the hopper 14- is therefore 4.
It is to. be understood that the .compacting which is efiected by the plugs suchas 17 and 42 is done in a single stroke accomplished normally in about A of asec- 0nd. Refraction of the plug is also effected in A of a second. A typical catalyst feed or hopper fill will consume about 10 seconds while adjusting the pressure in the hopper 13 takes about seconds. It will be appreciated therefore that a cycle of the type described above is completedin just over /z a minute.
In a system of the type described, the contact material leaving the regenerator and entering the hopper 14 is very hot, beingfrom 900 to 1300" F. Electric and mechanical parts need to .be' protected at these temperatures and.
Q for this reason it is'proposed to surround the operating gas through the conduit 33.' The cool gas'bath es-the windings 34 of the stator of the solenoid and then leaves the container 32 through the pipe 35." The electrical leads to the stator are suitably protected by means known to the art outside of the container 32 and within the container these leads 36 are protected by the cooling gas- Similar protection is afforded to the leads 37 to the arma' ture 38" ofthe solenoid. The armature 38 is fixed on one I end of a rod 39 which at its other end is connected to the plug 17. A rather long guide bearing is provided at 40 and this bearing is subjected to the cooling action of the 3 gas entering the container 32.. a
While the foregoing description has been concerned with the solenoid 25, it is to be understood that the identical. arrangement willfb'e' used with solenoid'24'.
In reference to Figure .4, there is shown a 'Sylphon' bellows '41 a's'an operator for a conical plug 42 in a: hopper '43; The'Sylphon bellows is actuated by the application of a pressure fluid thereto through the conduit 4'4. The bellows is encased in a housing 45 containing a shaft bearing 46*and the housing 45 lies withida jacket 47. to which the cooling fluid is supplied through conduit 48 and withdrawn through the conduit 49. The plug shown in Figure 4 can be used in installations such 7 as are shown in Figures 1 and 2. It acts as a piston at the top of the seal leg preventing expansion of the catalyst and subsequent loss of se'aliagainst reactor pressure For this'design to be effective the conical point of the plunger 3 42 must have angle 0 (measuredf'from the axis of sylrimetry' of the plunger) which" is notless than the angle o of the conical bottom of the hopper. When these'twoh angles areiequal the sides of the plunger and the hopper.
walls are parallel and an advance of the plunger afon'gi 1 the axis for symmetry in the direction of the hopper wall will place the catalyst particles in compression. Note in Figure 4 that the angle 0 is larger than the corresponding;
'angle in'the Figure 3 construction, 0' in Figure 4 being greater than 12 but less than 45 While the Sylphon' bellows is shown as the actuator for the form of tamping' plug shown in Figure 4, it is also suitable for actuatinga plug of the Figure 3'type as isthe solenoid for actuating'a plug of the Figure 4" type g I What is claimed is:
1-. Apparatus for transferring solid material of palpable particulate formfrom one location to another, the com-' bination which comprises: a supply hopper, a depending conduit attached below said supply hopper, a pressuring hopper attached to the bottom of said conduit, meansfor alternately increasing and decreasing the pressure in said pressuring hopper, means defining a discharge outlet from said pressuring hopper for the withdrawal of solid material, means for supplying solid material to said supply hopper, and tamping means located within said conduit and suppiy hopper adapted for downward movement to compact the solid material at approximately the same time that the'pressure in said pressuring hopper is increased, whereby the pressure sealing capacity of the apparatus is increased.
'2. Apparatus.for'introducing solid material of palpable particulate form into a high pressure vessel, the combination which comprises: a supply hopper -locatedabove the high pressure vessel, a pressuring hopper located between the supply hopper and the high pressure vessel;
a first connecting conduit of restricted cioss-sectioncon adapted for downward movement substantially simulta 5 neously with the increase of pressure in the pressuring hopper, whereby the solid material in said first connecting conduit is made more compact, and a second tamping means located within the pressuring hopper and the second connecting conduit adapted for downward movement substantially simultaneously with the reduction of pressure in the pressuring hopper, whereby the solid material in said second connecting conduit is made more compact.
1,971,716 Hitchcock Aug. 28, 1934 6 Schlesman Mar. 16, Rogers Oct. 14, Loss Apr. 25, Adams Nov. 14, Morrow Oct. 16,
FOREIGN PATENTS Great Britain Nov, 9, Great Britain NOV. 18,