MXPA01008447A - Standpipe inlet for enhancing particulate solids circulation for petrochemical and other processes - Google Patents

Abstract

Apparatus comprising means for keeping a bed of particulate solids in a fluidized bed mode in a vessel, a conduit for transferring said particulate solids into the resulting fluidized bed and a standpipe, protruding into said fluidized bed, for transferring particulate solids out of the fluidized bed, wherein a disk surrounding the standpipe is present below the upper part of the standpipe, which upper part the standpipe comprises an inlet for receiving solids from the fluidized bed.

Description

VERTICAL TUBE ENTRY TO INTENSIFY THE CIRCULATION OF SOLIDS IN THE FORM OF PARTICLES, FOR PROCESSES PE TROQUIMICOS AND OTHER PROCESSES FIELD OF THE INVENTION The invention relates to a damper vertical tube inlet design for intensifying particle circulation and reducing gas entrainment, the design is suitable for applications in catalytic fluid pyrolysis units (FCC) and others. processes such as fluid cokers, flexicoquizadores, and fluidized bed combustion chambers, which circulate large amounts of solids in the form of particles, between different vessels connected with vertical buffer tubes and riser tubes.

BACKGROUND OF THE INVENTION In a typical process of fluid catalytic pyrolysis (FCC) consisting of a regenerator, a riser reactor and a scrubber, such as that presented in US Pat. No. 5,562,818 issued to Hedrick, regenerated, finely divided catalyst , comes out REF .: 132172 of a regenerator and makes contact with a hydrocarbon feed in a lower portion of a riser of the reactor. The hydrocarbon feed and steam enter the riser through feed nozzles. The feed, steam and regenerated catalyst mixture, having a temperature from about 200 ° C to about 700 ° C, passes upwards and through the riser reactor, converting the feed into lighter products, while a layer of coke It is deposited on the surface of the catalyst. The hydrocarbon vapors and the catalyst from the top of the riser are then passed through cyclones to separate the spent catalyst from the hydrocarbon vapor product stream. The spent catalyst enters the scrubber where steam is introduced to remove hydrocarbon products from the catalyst. The spent catalyst, which contains coke, then passes through a vertical buffer tube of the scrubber, to enter the regenerator, where in the presence of air and at a temperature from about 620 ° C to about 760 ° C, the combustion of the Coke layer produces regenerated catalyst and combustion gas. The combustion gas is separated from the entrained catalyst, in the upper region of the regenerator, by cyclones, and the regenerated catalyst is returned to the fluidized bed of the regenerator. The regenerated catalyst is then removed from the fluidized bed of the regenerator, through the buffer vertical tube of the regenerator and, repeating the previously mentioned cycle, makes contact with the feed in the reaction zone. The circulation of the catalyst is critical to the overall performance and reliability of the FCC units. The main source of impulsion for the circulation of the catalyst comes from the formation of pressure, stable and adequate, in the vertical absorber tube. A critical element of the vertical damper tube design is the design of the vertical damper tube is the design of the inlet, because this determines the condition of the catalyst at the inlet, which in turn affects the overall operation of the vertical damper tube. The prior art design of vertical damper tube inlets, both for vertical tube buffer of a scrubber as well as a vertical tube damper for a regenerator, is a conical hopper, such as that shown in the literature disclosed in The Process Manual of Refining of the Petroleum, second edition by RA Meyers. The key design concept of the entry hopper of the prior art is that when the catalyst particles are removed from a fluidized bed into a buffer tube, bubbles are also removed together with the catalyst. The entrance hopper provides the residence time for the bubbles to fuse and grow to form large bubbles before entering the buffer vertical tube. Since large bubbles have a higher velocity in the riser tube, these have a better chance of escaping back to the fluidized bed, thus reducing the drag of gas towards the vertical damper tube. However, the design concept of vertical damper tube inlet of the prior art has many disadvantages. If the inlet hopper is too small, many bubbles entrained into the inlet hopper do not have enough time to grow, but instead flow directly into the vertical damper tube, leading to a high gas drag. If, on the other hand, when the inlet hopper is large enough to allow small bubbles to grow, large bubbles may form and hang stationary within the hopper, for such a period of time that the bubbles tend to rise against it. descending catalyst flow. These large suspended bubbles can restrict the flow of catalyst into the buffer tube temporarily. When the bubbles finally grow enough to escape into the fluidized bed, the release of the large bubbles creates a sudden surge of the catalyst into the buffer tube, leading to a sudden pressure oscillation within the buffer tube. The sequence of growth and release of large bubbles leads to a very undesirable condition of unstable operation of the buffer tube. The main design flaw of the prior art is that, while it is assumed that the design goal of the vertical intake cushion tube is to reduce gas entrainment into the shock absorber vertical tube, the design actually encourages many bubbles to be drawn into inside. Inherently this is very inefficient. In addition, the design of the entry hopper of the prior art is a high volume structure, such that in many FCC units there is not enough space to place it. A common commitment is to use either a straight tube or an asymmetric hopper for the intake of the vertical shock absorber that further exacerbates the problems described above. The geometry of the intake of the vertical damper tube not only affects the circulation of the catalyst, the entrained gas can also have a negative impact on the operation of a scrubber of an FCC unit. A common practice is that the scrubber includes special dishes, such as those shown in the invention of Johnson et al, in International Patent PCT / US95 / 09335. The special plates in the main vessel intensify the efficiency of steam hydrocarbon steam cleaning. The spent catalyst is then transported to the regenerator through a vertical tube of the scrubber, vertical damper tube with a hopper inlet as shown in the prior art. It has been shown that the hopper inlet for the buffer tube of the scrubber is quite inefficient to reduce gas entrainment. The Nougier et al. Study at the Second FCC Forum (May 15-17, 1996, The oodlands, Texas) shows that even after intensive purification in the main vessel, steam leaving the scrubber still contains 20 to 25 % in mol (or approximately 40% by weight) of hydrocarbon products. The gas drag of the buffer tube of the scrubber within the regenerator has two negative impacts in addition to the impact on the catalyst circulation mentioned above. First, the gas carried from the scrubber to the regenerator represents a loss of hydrocarbon products that could have been recovered as products. Secondly, the entrained hydrocarbon has to be burned in the regenerator, which consumes the little air available in the regenerator, thus generating additional heat that must be removed. In this way, it is essential to reduce the gas drag to the buffer tube of the scrubber.

DESCRIPTION OF THE INVENTION It is an object of the present invention to reduce the entrainment of gas towards the vertical shock absorber tubes by means of an inlet design of the vertical damper tube. This will lead to increases in the formation of the total pressure in the vertical shock absorber tube and in the rate of catalyst circulation, as well as in the improvement of the stability of the vertical shock absorber tube. The reduction of gas entrainment will also reduce the carryover of hydrocarbons from the scrubber to the regenerator of an FCC unit, as discussed above. These objectives are achieved with the following device. The apparatus comprises means for maintaining a bed composed of particulate solids, in a fluidized bed mode, in a vessel, a conduit for transferring the particulate solids to the resulting fluidized bed and a buffer vertical tube, protruding into the fluidized bed, to transfer solids in the form of particles outside the fluidized bed, where a disc surrounding the circumference of the vertical shock absorber tube is present below the upper part of the vertical absorber tube and above means to maintain a bed of solids in the form of particles in a fluidized bed mode, the upper part of the vertical damper tube comprises an inlet for receiving solids in the form of particles, coming from the fluidized bed, the disk induces, during use, a partial, local defluidization, which gives as a result a dense local fluidization zone, above at that site, and close to the Duct input vertical shock absorber. Applicants have discovered that with the apparatus according to the invention, the solids flow smoothly into the buffer tube with less gas drag than described above. More advantages will be described below. The main drive for the catalyst circulation in FCC units comes from the adequate and stable pressure formation inside the vertical damper tube. A critical element of the vertical damper tube design is the design of the inlet, because it determines the input condition of the catalyst, which, in turn, affects the overall operation of the vertical damper tube. It is essential to reduce gas entrainment through a suitably designed vertical damper tube inlet. The key concept of the present invention, the design of the damper vertical tube inlet is totally different from the design of the input hopper of the prior art, which has several disadvantages previously analyzed. The design concept of the present invention is based on partial defluidization, rather than melting and bubble growth inside the hopper, to reduce gas entrainment, which will be discussed in detail below. The reason why the FCC catalyst can be maintained in a fluidized state in the regenerator or in the scrubber is by means of a continuous, upflowing fluidizing gas supply. In this way, as soon as the supply of the fluidizing gas is suspended, the fluidized catalyst begins to settle, or is defluidized immediately. In the initial stage of this defluidization process, bubbles escape very rapidly from the fluidized bed, as shown by Khoe et al in Powder Technology Vol. 66 (1991) which is incorporated herein by reference. After depletion of all bubbles, the FCC catalyst can still be maintained in a state of dense fluidization for a certain period of time before it becomes completely de-luidized, as also shown in Khoe et al. In the experiments carried out by Khoe et al, the defluidization process was activated by cutting off the supply of the fluidization gas, leading to defluidization of the entire fluidized bed. The applicants now discovered that, by means of the strategic blocking of the fluidizing gas, with upward flow, in a selected area a defluidization process is achieved within a fluidized bed. The present invention of the vertical damper inlet design utilizes this partial defluidization in a strategic area to eliminate the bubbles and allow only the densely fluidized catalyst to flow into the buffer tube. The apparatus according to the invention will further describe making use of the following non-limiting Figures.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view of the lower portion of a regenerator of an FCC unit including a buffer vertical tube of a regenerator.

Figure 2 is an enlarged sectional view of a portion of Figure 1 of the intake of the buffer vertical tube of the regenerator. Figure 3 is an alternative embodiment of Figure 2 of the vertical absorber tube inlet of the regenerator. Figure 4 is another embodiment of the vertical damper tube inlet of the regenerator, when the catalyst is removed from a space near the bottom wall of the regenerator vessel of an FCC unit. Referring now to Figure 1 which consists of a sectional view of the lower portion of a typical container 20 of a regenerator of an FCC unit, wherein the buffer vertical tube 10 of the regenerator includes an inlet portion 60 to be removed by the same the regenerated catalyst according to the present invention. The spent catalyst is transported from a scrubber (not shown) through a conduit 70 for the transport of spent catalyst and enters the regenerator 20 where the deposition of coke on the catalyst is burned by air supplied by a main air grille 30. The air from the grate 30 and the gas resulting from the combustion rise through the regenerator, thus maintaining the fluidized catalyst in the fluidized bed 40. The combustion gas and the regenerated catalyst, entrained, are separated at the top of the regenerator by means of cyclones (not shown). The combustion gas leaves the top of the regenerator, and the regenerated catalyst, separated by the cyclones (not shown), returns to the fluidized bed 40. The typical density of the fluidized bed 40 in the regenerator 20 is in the range of 0.32. -0.64 g / cm3 [of 20 to 40 pounds / ft3], with the presence of enough ascending gas bubbles. The density of the fluidized bed 40 is controlled mainly by means of the air flow of the air grid 30 where a greater flow of fluidizing air creates more gas bubbles and lower density of the fluidized bed 40. The fluidized bed 40 is kept to a certain level 50 by means of a slide valve (not shown), or other means, located at the bottom of the vertical tube 10 of the regenerator, to control the rate of the regenerated catalyst that is removed by the vertical tube 10 of the regenerator. The upper part of the vertical tube 10 of the regenerator, including an inlet 60 of the buffer tube according to the present invention, shown enclosed by the dotted circle, is completely submerged in the fluidized bed 40 within the regenerator 20. Although the tube vertical shock absorber 10 is shown in Figure 1 as vertical and protruding in the regenerator 20 from the bottom, the present invention of the inlet 60 of the buffer vertical tube 60 can be applied to other configurations where the vertical shock absorber tube 10 can protrude into the regenerator 20 through the side wall, instead of the bottom of the container, and could be tilted, instead of vertical. Referring now to Figure 2 for the details of the inlet 60 of the buffer tube in Figure 1, the buffer tube 10 of the regenerator is typically a cylindrical conduit with a diameter in the range of about 0.30 to 1.52 m (of 1 to 5 feet). The regenerated catalyst is preferably removed by the buffer vertical tube 10 through one of two types of openings, or both. The first preferred embodiment for the opening is an opening 11 of the upper surface of the buffer tube. The second preferred embodiment for the opening is a plurality of openings 12 cut through the walls of the upper portion of the vertical tube 10. Although in FIG. 2 slits are shown for the openings 12, other shapes could also be used, such as circular holes. Beneath the openings 11 and / or 12 there is a horizontal disk 13 surrounding the vertical damper tube 10. In the following analysis, the element 13 will be referred to as a "disk", which is the most logical way for a container to form cylindrical However, it will be appreciated that the element 13 may simply be a plate of any desired shape. Because the entire inlet of the buffer vertical tube is immersed in the fluidized bed 40 where the catalyst is fluidized by the continuous upward flow of the fluidizing gas coming from the air grill 30 (see Figure 1), the disk 13 blocks strategically the supply of fluidizing gas coming from the bottom and activates the process of local defluidization in the region directly above the disk 13. Since the regenerated, fully fluidized catalyst, together with gas bubbles are withdrawn towards the tube openings vertical shock absorber 11 and 12, the fluidizing gas is blocked by the disk 13 (except as will be described later) and the bubbles that migrate towards the openings 11 and 12 of the vertical damper tube exit quickly from the continuous supply of fluidizing gas. This creates a dense fluidized zone 14, which is shown by the dotted line in Figure 2, with little presence of bubbles in the vicinity of the openings 11 and 12 of the vertical damper tube. This allows the catalyst to partially defluidize by removing the gas bubbles before entering the buffer vertical tube 10, but not to the extent of total defluidization in which the catalyst can no longer flow. In order to prevent total defluidization in the dense fluidization zone 14 above the disk 13, a small gas flow is preferably supplied. The small gas flow is preferably supplied through the ventilation holes 13c in the disc 13 and / or through the contact of a gas injection ring 15 located above the disc 13. Although in FIG. 2 an injection ring is shown in FIG. gas 15, other means, such as a gas injection grid, can also be employed to achieve the same goal of preventing total defluidization in the dense defluidization zone 14 above the disk 13. The disk 13 suitably includes one side or lip 13a projecting downwards surrounding the disc 13, preferably in its circumference. The vacuum below the disk 13 surrounded by the lip 13a allows the disk to capture the fluidizing gas coming from below. To continuously ventilate the fluidizing gas, the lip 13a conveniently further includes a plurality of vent holes 13b which allows the fluidizing gas to be vented out of the dense fluidization zone 14. Alternatively a vent pipe 16 can be used to discharge the fluidizing gas from below the disk 13 to a site above the dense defluidization zone 14. Although a horizontal disk 13 is proposed as a means to achieve local defluidization in the dense fluidization zone 14 shown in Figure 2, it can be apply other means to achieve the same goal. One of those alternatives is shown in Figure 3. Referring now to Figure 3, the regenerated catalyst is withdrawn back into the buffer vertical tube 10 'through the upper opening 11', or a plurality of openings 12 ', or both. Instead of using a horizontal disc 13 as in Figure 2, Figure 3 shows that below the openings 11 'and 12' there is a conical disk 13 'surrounding the buffer vertical tube 10'. The function of the tapered disk 13 'consists in the strategic blocking of the fluidizing gas supply coming from the lower part and activating the local defluidization process in the region placed directly above the disk 13'. This creates a dense defluidization zone 14 ', enclosed by the dotted line of Figure 3. To prevent total defluidization in the dense defluidization zone 14 ', a small gas flow is preferable, either by means of ventilation holes 13c' in the disc 13 'and / or through a gas injection ring 15 'located above the disk 13'. Although a gas injection ring 15 'is shown in Figure 3, other means such as a gas injection grid can also be used, achieving the same goal of preventing total defluidization in the dense defluidization zone 14' above the disc 13 '. The vacuum below the tapered disk 13 'allows the disk to capture fluidizing gas from below. To continuously ventilate the accumulation of the fluidizing gas, the disc 13 'also appropriately includes a plurality of ventilation holes with extension tubes 13b' which allows the fluidizing gas to be extracted from the dense defluidization zone 14 '. Alternatively, a vent tube can be used to discharge fluidizing gas from below the disk 13 'to a site above the dense defluidization zone 14'. One advantage of the conical disc 13 'with respect to the horizontal disc 13 shown in Figure 2 is that the catalyst is less likely to stagnate when the gas flow from the gas injection ring 15' is stopped. Figure 4 shows another embodiment of a damper vertical intake of a regenerator using a design similar to the concept shown in Figure 1 except when in the FCC process it is preferred to remove the regenerated catalyst from a region very close to the bottom of the regenerator. 120. The spent catalyst is transported from a scrubber (not shown) through a conduit for the transport of the spent catalyst and enters the container 120 of the regenerator. The regenerated catalyst is separated from the combustion gas in the upper part of the regenerator, by means of cyclones (not shown). The combustion gas leaves the top of the regenerator vessel and the regenerated catalyst is separated by cyclones (not shown) is returned to the bottom of the regenerator vessel 120 to form the fluidized bed 140 by means of the continuous upward flow of air fluidizer and the combustion gas coming from the air grille 130. The fluidized bed 140 is maintained at a level 150 by means of a sliding valve (not shown), or through other means, located at the bottom of the buffer vertical tube 110 of the regenerator, to control the rate of regenerated catalyst that is removed by the vertical damper tube 110 of the generator. In this embodiment, the disk surrounding the buffer vertical tube 110 forms part of the lower end of the container 120 of the regenerator. The buffer vertical tube 110 of the regenerator still has one of two types of inlet openings, or both, for removing catalyst from the fluidized bed 140 of the regenerator vessel. The first opening is the upper opening 111 of the buffer vertical tube 110 and the second consists of a plurality of openings 112 cut through the walls of the upper portion of the buffer vertical tube 110 just above the bottom wall of the container 113 of the regenerator 120. Although the vertical damper tube 110 is shown in Figure 4 as vertical, the present invention of the damper vertical tube inlet can also be applied to other configurations wherein the damper vertical tube 110 could be inclined. The function of the wall 113 of the lower end of the regenerator vessel shown in Figure 4 is similar to that of the disk 13 shown in Figure 2, that is, to induce local defluidization and create a dense defluidization zone 114 (as in the zone 14 shown in Figure 2) with few bubbles present in the vicinity of the openings 111 and 112 of the vertical damper tube. To prevent total defluidization near the container wall, a small gas flow can be provided through a gas injection ring 115. Although a gas injection ring is shown in Figure 4, other means may also be employed, such as a gas injection grid for achieving the same goal of preventing total defluidization in the denuded defluidization zone 114 above the wall 113 of the container. According to Figure 4, the inlet of the buffer vertical tube of the regenerator was installed in one of the FCC units of the transferee, which originally had a hopper damper vertical tube inlet of the prior art design. The original hopper inlet was removed and four slits measuring 15.24 cm wide by 101.6 cm long (6 inches wide by 40 long) were created in the wall of the vertical damper tube. After the installation of the new intake of vertical generator damper tube, the catalyst circulation rate of the FCC unit increased approximately 30%, with an additional pressure formation of 0.21 kg / cm2 (3 psi) in the vertical tube regenerator cushion. This was a clear indication that the vertical damper tube inlet of the present invention was very effective in reducing the entrainment of the gas coming from the regenerator, thus allowing the vertical damper tube to operate at a higher density and higher pressure to be formed. to increase the circulation of the catalyst. In addition, the vertical damper tube operation became more stable even at a higher catalyst circulation rate, compared to previous operation. From the previous analysis it is shown that the design of the vertical damper tube inlet of the present invention has several advantages over the design of the prior art inlet hopper when applied to the regenerator damper vertical tube of an FCC unit : More Stable Operation: The input design of the present invention is not based on the prior art hopper mechanism for removing many bubbles, allowing them to merge and transform into larger bubbles. Instead, the new inlet design minimizes bubble entrainment by strategically eliminating bubbles around the inlet region of the vertical tube with local defluidization. Since the new design does not require the formation and discharge of large bubbles in the design of the hopper, which leads to instability in the vertical shock absorber tube, the design of the present invention is inherently more stable. Greater effectiveness in reducing gas entrainment: The concept of the entry hopper of the prior art consists of removing a large amount of bubbles while attempting to reduce gas entrainment. Inherently this is a very inefficient design. On the other hand, the basic design of the present invention consists of the strategic elimination of bubbles by means of the local defluidization of the catalyst before it enters the vertical damper tube. In this way, the design of the present invention is inherently more efficient in reducing the drag of the gas towards the buffer tube. Better control: The hopper inlet of the prior art has little control of gas entrainment around the inlet. As the rate of catalyst circulation increases, more and more bubbles are drawn into the hopper, leading to an increasing gas drag. The design of the present invention, on the other hand, maintains full control of the flow condition near the inlet through the elimination of all bubbles, thus introducing only a small amount of gas necessary for smooth operation. Simplicity: The design of the present invention is simpler and more robust than the hopper design of the prior art. When the vertical damper tube design of the present invention is applied to the buffer vertical pipe of the scrubber, provides several additional advantages over hopper design prior art, to intensify the operation of the debugger and regenerator of an FCC unit. This in addition to the benefits previously analyzed for the application in the buffer vertical tube of the regenerator where the circulation of the catalyst and the stability of the vertical tube damper are the main interests: Higher efficiency in the purification: The design of the vertical tube inlet absorber of the present invention proves to be more effective in reducing gas entrainment into the buffer vertical tube. Since the entrained gas from the vertical buffer tube of the scrubber can contain approximately 40% by weight of hydrocarbon products, the inlet design of the vertical damper tube of the present invention effectively increases the hydrocarbon products by reducing the loss of hydrocarbons due to the gas drag. Lower Regenerator Load: Since the inlet design of the vertical damper tube of the present invention is more effective in reducing gas entrainment, the amount of hydrocarbons entering the regenerator will be less. This leads to less air requirement and less heat being removed, since less hydrocarbons will be burned in the regenerator. More importantly, several FCC units are currently limited by the air supply or by the heat removal capacity in the regenerator. In this way, the present invention can be used to eliminate bottlenecks in the unit.

Although the above analysis focuses on the applications of the present invention in FCC units, a similar design can also be applied to improve the circulation of particulate solids and reduce gas entrainment in other petrochemical processes, such as cokers and fluid flexicoquizadores, and processes different to the petrochemicals, such as combustion chambers with fluidized bed, with circulation, where large amounts of solids in the form of particles are circulated between different vessels connected by vertical tubes dampers and risers.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (20)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. The apparatus characterized in that it comprises means for maintaining a bed of particulate solids in a fluidized bed mode inside a container, a conduit for the transfer of said particulate solids to the resulting fluidized bed and a vertical tube damper, projecting in the fluidized bed, to transfer solids in the form of particles outside the fluidized bed, wherein a disk surrounding the circumference of the vertical damper tube is present below the upper part of the vertical damper tube and means located above to maintain the bed of particles in the form of solids in a fluidized bed mode, the upper part of the vertical damper tube comprises an inlet for receiving solids in the form of particles from the fluidized bed, the disk induces, during use, a partial defluidization local, resulting in a dense local defluidization zone above on that site, and close to the proximity of the entrance of the vertical absorber tube. The apparatus according to claim 1, characterized in that the inlet located in the upper part of the buffer vertical tube comprises a plurality of openings cut through the buffer tube wall below the upper end and above the disk. The apparatus according to claim 2, characterized in that a plurality of openings are vertical slits cut through the buffer tube wall below the upper end and above the disk. The apparatus according to any one of claims 1 to 3, characterized in that a means for injecting fluidizing gas to maintain a dense fluidization zone of the solids in the form of particles located above the disk is present above the disk. that place. The apparatus according to any one of claims 1 to 4, characterized in that the upper end of the buffer tube is open. The apparatus according to any of claims 1 to 5, characterized in that a means for venting the gas coming from the lower part of the disk is present. The apparatus according to claim 6, characterized in that the ventilation means are holes in the disc. The apparatus according to claim 7, characterized in that the ventilation means is a tube that connects the region below the disc and the region above the upper end of the inlet tube. The apparatus according to any of claims 1 to 8, characterized in that a downward projection is present on the circumference of the disk. The apparatus according to claim 9, characterized in that the lip comprises a plurality of ventilation holes. The apparatus according to any of claims 1 to 10, characterized in that the disk has a conical shape pointing towards the upper end of the buffer vertical pipe. 1

2. The process of transferring solids in the form of particles outside a fluidized bed has a density in the range of 0.32-0.64 g / cm3 through a vertical shock absorber tube, which projects into the fluidized bed, where the inlet said vertical shock absorber tube that receives particulate solids from the fluidized bed is located near the bottom wall in a position in which the local density is above 0.64 g / cm

3. The process according to claim 12, characterized in that the fluidizing gas is added to the fluidized bed to maintain a dense fluidization zone of the particulate solids located above the bottom of the container and near the vicinity of the inlet of the vertical tube shock absorber. 1

4. The process according to any of claims 12 to 13, characterized in that the entrance in the upper part of the vertical damper tube comprises a plurality of openings cut through the wall of the damper vertical tube below the upper end and above the bottom wall. 1

5. The process according to claim 14, characterized in that a plurality of openings are vertical slits cut through the buffer tube wall below the upper end and above the bottom wall. 1

6. The process according to any of claims 12 to 15, characterized in that the upper end of the buffer tube is open. The process according to any of claims 12 to 16, characterized in that the particulate solids are catalyst particles from the catalytic pyrolysis of fluids, solids which are maintained in a fluidized mode by means of air and wherein the coke deposited in the spent catalyst is burned by air. 18. The process according to any of claims 12 to 16, characterized in that the particulate solids are catalyst particles of the catalytic pyrolysis of fluids, solids that are kept in fluidized mode by means of steam. 19. A regenerative apparatus of a catalytic fluid pyrolysis unit, characterized in that it comprises the apparatus according to any of claims 1 to 11. 20. The purifying apparatus of a fluid catalytic pyrolysis unit, characterized in that it comprises the apparatus according to any of claims 1 to 11.