US2854161A - Hydrocarbon conversion - Google Patents

Description

Sept. 1958 J. w. PAYNE 2,854,161

HYDROCARBON CONVERSION 2 Sheets-Sheet 1 Original Filed Nov. 8, 1954 Sept 30, 3958 J. w. PAYNE HYDROCARBON CONVERSION Original Filed Nov. 8, 1954 2 Sheets-Sheet 2 J 1+ m N E 0 m a no u N T m m A n n i J L I L Y Am m 5 W m E T m COOLI G GAS United States Patent O HYDROCARBON CONVERSION John W. Payne, Woodhury, N. 3., assignor to Socony Mobil Oil Company, Ina, a corporation of New York Original application November 8, 1954, Serial No. 467,501. Divided and this application April 30, 1958, Serial No. 731,952

2 Claims. ((11. 214152) 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 difierent 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 ofi. 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 suificient 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 effort 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 static pressure 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 sufiicient 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 re quired 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 and to operate these in a cyclic manner with periodic ice 2 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 1 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 difierent 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 generally 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 10 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 therethro-ugh of fluids under such pressures 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 20 discharging funnel-like into the top zone 12 of the reactor 10. 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 tunnellike portion of small cross-section 23 leading into the top of hopper 13. Tapered plugs 15 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 20 or 23 respectively.

The hopper 14 is vented to atmosphere by a pipe 26. A pipe 27 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 10 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 Figure 1, the

solenoid 24 is actuated to drive theplug 16 downwardly to compact the contact material in the narrow portion 20 of the hopper 13. Valve 28 is adjusted to the Figure 1 position to vent the hopper 13 to atmosphere. Hopper 14 is continuously vented to atmosphere so that there is no appreciable difference in pressure between the interior of the hoppers 13 and 14 at this stage of the operation. The length 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, bearing in mind that somewhere in the portion 19 of the hopper 13 the gas velocity falls below bed disrupting value and bearing in mind that even at the beginning of the refill of hopper 13 there is suflicient contact material above the plane Where the bed disrupting velocity no longer exists to hold the contact material in position.

In Figure 1 the plug 17 is shown in its upper or retracted position so that the contact material can and does flow freely out of the hopper 14 and into the hopper 13. When the hopper 13 has been adequately filled the flow cycle is changed from that shown in Figure l 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 23 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 zone 12 of the reactor. While this is happening the pressure drop across the portion 23 is held by exactly the same phenomenon as was described in connection with the portion 20 in the Figure 1 position. The hopper 14 can be filled because its upper empty spaces are at atmospheric pressure. By the time the hopper 14 i adequately filled, hopper 13 will be low and the zone '12 will be high. Threreupon 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 20-23) 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 19-22), 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 3. The most effective taper is an acute angle theta with the angle phi of the portion 23 greater 7 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 effected by the plugs such as 17 and 42 is done in a single strokeaccomplished normally in about 5 of a second. Retraction of the plug is also effected in a ,4 of a second. A typical catalyst feed or hopper fill will consume about 10 seconds while adjusting the pressure in the hoppcr'13 takes about seconds. It will be appreciated, therefore, that a cycle of the type described above is completed in just over /2 a minute.

in a system of the type described, the contact material leaving the regenerator and entering the hopper 14 is very hot, being from 900 to 1300 F. Electric and mechanical parts need to be protected at these temperatures and for this reason it is proposed to surround the operating mechanism for the plugs with a cooling jacket. If reference is made to Figure 3, it can be seen that the solenoid 25 is surrounded by a jacket 32 supplied with a cooling gas through the conduit 33." The cool gas bathes 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 aiforded to the leads 37 to the armature 38 of the solenoid. The armature 38 is fixed on one end of a rod 39 which at its other end is connected to the plug 17. A rather long guide bearing i provided at 40 and this bearing is subjected to the cooling action of the gas entering the container 32.

While the foregoing description has been concerned with the solenoid 25, it is to be understood. that the identical arrangement will be used with solenoid-24;

In reference to Figure 4, there is showna Sylphon bellows 41 as an operator for aconical plug 42 in a hop-- per 43. The Sylphon bellows is actuated by the applica-..

tion of a pressure fluid thereto through the conduit 44.

The bellows is encased in a housing 45 containinga shaft bearing 46 and the housing 45 lies within a 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 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 seal against reactor pressure. For this design to be etfectivethe conical point of the plunger.- 42 must have angle 9 (measured from the axis of syinzmetry of the plunger) which is not less than the anglet of the conical bottom of the hopper. When these two angles are equal the sides of the plunger and the hopperwalls are parallel and an advance of the plunger along the axis for symmetry in the direction of the hopperiwall 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, ing 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 7 also suitable for actuating a plug of the Figure 3 type as is the solenoid for actuating a plug of the Figure 4 type.

This application is a division of application Serial- Number 467,501, filed November 8, 1954.

I claim: 1

1. In a process for transferring solid material of palpable particulate form from one location to anothenthe method comprising: maintaining a supply of the solid material in a supply zone, passing the solid material downwardly from the supply zone through a confined.

passage as a compact gravitating column into a pressuring zone located therebelow, periodically removing solid material from said pressuring zone while placing said pressing zone under an advanced gaseous pressure, si-

multaneously mechanically tamping the solid material in the confined passage to compact the material in said passage, and preventing disruption of the compactness of the column and upward discharge'of the solid material f from said passage by maintaining on top of said column of compacted material in said supply zone a compact bed of said solid material of substantially greater hori-' zontal cross-sectional area than said column in whichv gas escaping from said column decelerates, said bed being of sufiicient horizontal cross-sectional area and vertical depth to effect deceleration of the gas to a linear velocity below that which would disrupt the compactness of said' bed substantially before it reaches the surface of the bed;

whereby a seal is maintained by virtue of the compacted column of solid material preventing the escape of any substantial amount of gas from said pressuring zone.

0 in Figure 4 be- 2. A method for introducing solid material of palpable particulate form into a high pressure zone comprising: maintaining a supply of the solid material in a supply zone, gravitating the solid material downwardly from the supply zone through a first confined passage as a compact gravitating column into a pressuring zone located therebelow, periodically raising the pressure in the pressuring zone and simultaneously mechanically tamping the solid material in the first confined passage to compact the material in the passage, and preventing disruption of the compactness of the column and upward discharge of the solid material from said passage by maintaining on top of said column of compacted material in said supply zone a compact bed of said solid material of substantially greater horizontal cross-sectional area than said column in which gas escaping from said column decelerates below the bed disrupting velocity at a level substantially below the surface of the bed, at the same time gravitating the solid material downwardly from the pressuring zone through a second confined passage as a compact gravitating column into the high pressure zone located therebelow, periodically reducing the pressure in the pressuring zone and simultaneously mechanically tamping the solid material in the second confined passage to compact the material in the passage, and preventing disruption of the compactness of the column and upward discharge of the solid material from said passage by maintaining on top of said column of compacted material in said pressuring zone a compact bed of said solid material of substantially greater horizontal cross-sectional area than said column in which gas escaping from said column decelerates below the bed disrupting velocity at a level substantially below the surface of the bed, while at the same time gravitating solid material downwardly through the first passage to replenish the supply of solid material in said pressuring zone.

No references cited.

Claims (1)

1. IN A PROCESS FOR TRANSFERRING SOLID MATERIAL OF PALPABLE PARTICULATE FORM FROM ONE LOCATION TO ANOTHER, THE METHOD COMPRISING: MAINTAINING A SUPPLY OF THE SOLID MATERIAL IN A SUPPLY ZONE, PASSING THE SOLID MATERIAL DOWNWARDLY FROM THE SUPPLY ZONE THROUGH A CONFINED PASSAGE AS A COMPACT GRAVITATING COLUMN INTO A PRESSURING ZONE LOCATED THEREBELOW, PERIODICALLY REMOVING SOLID MATERIAL FROM SAID PRESSURING ZONE WHILE PLACING SAID PRESSING ZONE UNDER AN ADVANCED GASEOUS PRESSURE, SIMULTANEOUSLY MECHANICALLY TAMPING THE SOLID MATERIAL IN THE CONFINED PASSAGE TO COMPACT THE MATERIAL IN SAID PASSAGE, AND PREVENTING DISRUPTION OF THE COMPACTNESS OF THE COLUMN AND UPWARD DISCHARGE OF THE SOLID MATERIAL FROM SAID PASSAGE BY MAINTAINING ON TOP OF SAID COLUMN OF COMPACTED MATERIAL IN SAID SUPPLY ZONE A COMPACT BED OF SAID SOLID MATERIAL OF SUBSTANTIALLY GREATER HORI-

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