MX2008010414A - Stripping apparatus and process - Google Patents

Abstract

A baffle-style stripping arrangement for an FCC process has downcomers (66) radially extending from a central axis in a stripping section (32). The baffles (35) may comprise radial sectors (58) with edges (58c, 58d) of adjacent sectors defining downcomers. Each sector may comprise a perforate section (60) and an imperforate section (62). The downcomer section of a superjacent baffle is aligned with the imperforate section of a subjacent baffle to assure horizontal movement of catalyst across the upper surface of the baffle.

Description

DEVICE AND DEMETALIZATION PROCESS BACKGROUND OF THE INVENTION The present invention relates to devices and processes for the fluidized contact of catalyst with hydrocarbons. More specifically, the present invention relates to devices and processes for the demetallization of hydrocarbons entrained by, or adsorbed to, catalyst particles. DESCRIPTION OF THE PREVIOUS TECHNIQUE A variety of processes contact finely divided particulate material with a hydrocarbon-containing feed under conditions in which a fluid holds the particles in a fluidized condition to effect transport of the solid particles at different stages of the process. Fluidized catalytic disintegration (FCC) is an important example of such a process that contacts hydrocarbons in a reaction zone with a catalyst composed of finely divided particulate material. An FCC process unit comprises a reaction zone and a catalyst regeneration zone. In the reaction zone, a feed stream is contacted with finely divided fluidized solid particles or catalyst maintained at an elevated temperature and at a moderate positive pressure. The contact of the feed and the catalyst generally takes place in a vertical column, although It can occur in any effective arrangement such as known devices for contact in short periods. In the case of a vertical column, a mainly vertical duct comprises the main reaction site, where the effluent from the duct is emptied into a large-volume process tank, which is known as a reactor tank, or which can also be referred to as a tank. separation. The residence time of the catalyst and the hydrocarbons in the vertical column, necessary to essentially complete the disintegration reactions, is a few seconds or less. The vapor / catalyst stream leaving the vertical column can pass from the vertical column to a solid-vapor separation device located within the separation tank, or it can enter the separation tank directly without passing through an intermediate separation device. When there is no intermediate device, much of the catalyst falls out of the vapor / catalyst stream as this current exits the vertical column and enters the separation tank. One or more solid / vapor separation devices, almost invariably a cyclone separator, is normally located within the large separation tank, at its upper part. The reaction products are separated from a portion of the catalyst that continues to be drawn by the vapor stream through the cyclone or cyclones, and is purged the cyclone vapor and the separation zone. The spent catalyst falls to a lower place within the separation tank. The catalyst is continuously circulated from the reaction zone to the regeneration zone, and then back to the reaction zone. Accordingly, the catalyst acts as a vehicle for the transfer of heat from one zone to another, in addition to providing the necessary catalytic activity. In the process any FCC catalyst can be used. The particles typically have a size of less than 100 microns. The catalyst extracted from the regeneration zone is known as a "regenerated" catalyst. The catalyst charged to the regeneration zone is brought into contact with an oxygenated gas such as air or air enriched with oxygen, under conditions which produce the combustion of coke. This produces an increase in the temperature of the catalyst and the generation of a large quantity of hot gas which is extracted from the regeneration zone as a gas stream known as exhaust gas stream. Normally, the regeneration zone is operated at a temperature between 600 and 800 ° C. Additional information about the operation of the FCC reaction and regeneration zones can be obtained in U.S. Pat. 4,541,922, 4,541,923, 4,431,749, 4,419,221 and 4, 220, 623.

The rate of conversion of the feedstock in the reaction zone is controlled by regulation of the temperature, activity of the catalyst and amount thereof (i.e., ratio of catalyst to petrol) which is maintained within the reaction zone. The most common method for regulating the temperature in the reaction zone is by regulating the speed of catalyst circulation from the regeneration zone to the reaction zone, which simultaneously changes the catalyst to oil ratio. That is, if it is desired to increase the conversion rate within the reaction zone, the flow rate of the catalyst from the regeneration zone to the reaction zone is increased. This causes that there is more catalyst present in the reaction zone for the same volume of oil that is loaded in it. Since the temperature within the regeneration zone, in normal operations, is considerably higher than the temperature within the reaction zone, an increase in the rate of circulation of the catalyst from the regeneration zone to the reaction zone produces an increase in the temperature of the reaction zone. The composition and chemical structure of the feed to an FCC unit will affect the amount of coke deposited on the catalyst in the reaction zone. Normally, the greater the molecular weight, and the greater is the amount of Conradson carbon, insoluble heptane and the ratio of carbon to hydrogen in the feed charge, the higher the level of coke in the spent catalyst. A higher conversion also increases the level of coke in the spent catalyst. In addition, high levels of combined nitrogen, such as that seen in shale-derived oils, increase the level of coke in the spent catalyst. Processing heavier feed loads, such as deasphalted oils or atmospheric bottoms of a crude oil fractionating unit (commonly known as reduced oil) causes an increase in. all or part of these factors, and therefore causes an increase in the level of coke of the spent catalyst. As used herein, the term "spent catalyst" is intended to indicate catalyst used in the reaction zone that is transferred to the regeneration zone for the removal of coke deposits. The term is not intended to indicate a total lack of catalytic activity of the catalyst particles. The term "used catalyst" is intended to have the same meaning as the term "spent catalyst". Most of the hydrocarbon vapors that contact the catalyst in the reaction zone are separated from the solid particles by ballistic or centrifugal separation methods within the reaction zone. Without However, the catalyst particles used in an FCC process have a large surface area, which is due to the large number of pores in the particles. As a result, the catalytic materials retain hydrocarbons within their pores, on the external surface of the catalyst and in the spaces between the catalyst particles upon entering the demetallization zone. Although the amount of hydrocarbons retained in each catalyst particle is very small, the large amount of catalyst and the high rate of catalyst circulation typically used in a modern FCC process cause a significant amount of hydrocarbons to be extracted from the reaction with the catalyst. Therefore, it is common practice to extract, or demetall, hydrocarbons from the spent catalyst before passing it to the regeneration zone. Higher concentrations of hydrocarbons in the spent catalyst entering the regenerator increase its relative charge of carbon combustion, and cause higher regenerator temperatures. Avoiding the unnecessary combustion of hydrocarbons is especially important during the processing of heavy feed charges (relatively high molecular weight), since processing these feed charges increases the deposition of coke on the catalyst during the reaction, compared with the speed of coking with light feed loads, and increases the temperature in the regeneration zone. A better demetallization allows lower regenerator and higher conversion. The most common method for demetallizing the spent catalyst includes passing a demetallization gas, generally steam, through a catalyst stream, countercurrent to its flow direction. These steam demetallization operations, with varying degrees of efficiency, extract the hydrocarbon vapors entrained with the catalyst and adsorbed therein. The contact of the catalyst with a demetallization medium can be achieved in a simple open tank, as demonstrated in U.S. Pat. No. 4,481,103. The efficiency of the catalyst demetallization is increased by using vertically separated deflectors, to cause the catalyst to fall cascading from one side to the other, when descending through a demetallization device and contacting a countercurrent demetalization means. Moving the catalyst horizontally increases the contact between the catalyst and the demetallization medium to extract more hydrocarbons from the catalyst. In such arrangements, a labyrinthine route is printed to the catalyst by a series of deflectors located at different levels. This arrangement increases the catalyst and gas contact, since essentially does not leave an open vertical route of significant cross section through the demetallization device. Other examples of these demetallization devices for FCC units are described in U.S. Pat. Nos. 2,440,620, 2,612,438, 3,894,932, 4,414,100 and 4,364.905. These references describe the typical demetallization tank arrangement, which possesses a demetallization tank, a series of external deflectors in the form of frusto-conical sections directing the catalyst inwards and towards a series of internal deflectors. The inner deflectors are conical or frusto-conical sections centrally located, or supported in a vertical reactor column that ascends through the demetallization tank. The inner baffle deflects the catalyst outward and towards the outer deflectors, and vice versa, to promote horizontal movement. The demetallization means enters from below to the lower deflectors, and continues to rise from the bottom of a deflector to the bottom of the next successive deflector. Variations in baffles include adding skirts around the trailing edge of the baffle, as described in U.S. Pat. No. 2, 994, 659, and the use of multiple linear baffle sections at different baffle levels, as demonstrated in Figure 3 of U.S. Pat. No. 4, 500, 423. In the patent of the USA No. 2,541,801 a variation is shown to introduce the demetallization medium, where a quantity of fluidizing gas is admitted in several discrete places. U.S. Pat. No. 5,531,884 shows a modification for a baffle type demetalizing tank, incorporating one or more large vertical conduits in the baffle, to provide an additional catalyst and gas flow path for the baffles. It is also known to concentrate openings in a centralized portion of the demetallization baffles. The deflectors in the demetallization tanks for the FCC units are typically oriented to have an angle of 45 ° with respect to the horizontal. The inclined deflectors ensure that the catalyst descends from the tray to the next level in the demetallization tank, to ensure a movement with a horizontal component. However, since each of the inclined trays occupy a significant elevation, they limit the number of trays that can be installed at a given height of a demetallization tank. The greater the number of trays in the demetallization tank, the greater the overall performance. On the other hand, fixing deflectors with a better inclination will cause the accumulation of catalyst on the deflector, unless the fluidization on the deflector is increased, which would require increasing the speed of the deflector. flow of the demetallization medium. U.S. Pat. No. 2002/0008052 Al reveals a highly fluidized demetallization baffle. U.S. Pat. No. 5,910,240 discloses frusto-conical demetallization baffles including blades cgured to impart rotary motion to the descending catalyst. U.S. Pat. No. 5,549,814 discloses a demetallization tank with inverted "U" -shaped, radially extending layers of an internal vertical column. The perforations in the arms of the "U" allow the passage of demetallization medium. The patent O 91/00899 discloses a demetallization tank with perforated horizontal trays. The fluidization in the demetallization tank is such that the catalyst descends from one tray to another, essentially only by sections of descending tubes of the respective trays. The catalyst material forms a dense bed on the upper surface of each tray, without significant amounts of catalyst being filtered by the perforations in the tray. This reference also discloses the use of baffle plates above the down tubes, which are vertically aligned in the center of an annular tray, and trays comprising wire mesh or series of bars. U.S. Pat. Do not. 2001/0027938 Al also reveals horizontal deflectors. SUMMARY OF THE INVENTION It has been discovered that a demetallization tank having deflectors with down tubes extending radially from the center of the deflector, or from an internal conduit, generates horizontal movement of the catalyst, generally in various angular directions on the surface of the deflector. . Accordingly, the catalyst extends more horizontally on the surface of each baffle, to provide greater contact with demetallizing means that flows upward. In one embodiment, the present invention comprises a device for the demetallization of particulate material hydrocarbons. The device comprises a demetallization tank and at least one port defined by the demetallization tank for receiving particles containing hydrocarbons, and for removing demetallization fluid and demetalated hydrocarbons from the demetallization tank. A plurality of demetallization baffles are vertically separated over at least a portion of the demetallization tank. One of the plurality of baffles includes at least three descending tubes that extend radially from a vertical center of the demetallization tank. A plurality of openings is distributed over at least a portion of the surface of one of the demetallization baffles. At least one fluid inlet passes a demetallizing fluid to a lower side of one of the demetallization baffles to demetallize hydrocarbons from the particulate material. The device includes at least one particle outlet for recovering demetallized particles from the demetallization baffles. In another embodiment, a conduit extends through the demetallization tank, and the descending tubes extend radially from the conduit. In yet another embodiment, the present invention comprises a process for demetallizing hydrocarbons from particulate material. The process comprises feeding particles containing hydrocarbons to a tank that includes a plurality of vertically separated demetallization baffles. One of the plurality of baffles includes a down tube that extends radially from a center of the demetallization tank. The down tube is limited by opposite non-parallel sides. A plurality of openings are distributed over at least one section of the surface of one of the demetallization baffles. The process further comprises passing a demetallization fluid to a lower side of one of the demetallization baffles to demetallize hydrocarbons from the particulate material. The fluid of Demetallization and demetallized hydrocarbons are recovered from the tank, and demetallized catalyst is collected from the tank. Accordingly, it is an object of the present invention to increase the demetallization efficiency in a baffle type demetallization tank. Other objects, embodiments and details of the present invention appear in the following detailed description of the invention. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic elevated view of an FCC reactor of the present invention. Figure 2 is an enlarged and partial perspective view of a demetallization section of the present invention shown in Figure 1. Figure 3 is a cross-sectional view taken of segment 3-3 in Figure 2. DETAILED DESCRIPTION OF THE INVENTION By first examining more details of an FCC process in which the present invention may be used, the typical feed to an FCC unit is a gas oil such as light or vacuum gas oil. Another stream of petroleum derivatives feeding to a FCC unit may comprise a mixture of hydrocarbons in the boiling range of diesel, or heavier hydrocarbons, such as reduced crude oils.

It is preferred that the feed stream consist of a mixture of hydrocarbons with boiling points, determined by the appropriate ASTM test methods, of more than 230 ° C, and more preferably of more than 290 ° C. It is becoming customary to refer to FCC-type units that process heavier feedstocks, such as atmospheric-reduced crudes, as residual crude disintegration units. The process and device of the present invention can be used for FCC or residual disintegration operations. For convenience, the rest of this specification will refer only to the FCC process. The reaction zone of an FCC process, which is commonly referred to as a "vertical column", due to the widespread use of a vertical tubular conduit or pipe, is maintained at high temperature conditions, which generally includes a temperature of more than 425 ° C. . Preferably, the reaction zone is maintained at disintegration conditions, including a temperature between 480 and 590 ° C, and a pressure between 65 and 500 kPa, but preferably less than 275 kPa. The ratio of catalyst to petroleum, based on the weight of the catalyst and the hydrocarbon feed entering the bottom of the vertical column, can vary up to 20: 1, although preferably it is between 4: 1 and 10: 1. Normally no hydrogen is added to the column vertical, although it is known in the art to add hydrogen. Occasionally steam can pass through the vertical column. The average residence time of the catalyst in the vertical column is preferably less than 5 seconds. The type of catalyst used in the process can be chosen from a variety of commercially available catalysts. A catalyst comprising a zeolite base material is preferred, although the old amorphous catalyst can be used, if desired. The regeneration zone of the catalyst is preferably operated at a pressure between 35 and 500 kPa. The spent catalyst that is charged to the regeneration zone may contain between 0.2 and 15% of the weight of coke. This coke is comprised predominantly of carbon, and may contain between 3 and 12% of the weight of hydrogen, as well as sulfur and other elements. The oxidation of coke will produce the common combustion products: water, carbon oxides, sulfur oxides and nitrous oxides. As is known to those skilled in the art, the regeneration zone can have several configurations, where the regeneration is carried out in one or more stages. A greater variety is possible, because regeneration can be achieved if the fluidized catalyst is present as a dilute or dense phase within the regeneration zone. The term "diluted phase" is intended to indicate a catalyst / gas mixture with a density of less than 300 kg / m3. Similarly, the term "dense phase" is intended to mean that the catalyst / gas mixture has a density equal to or greater than 300 kg / m3. Representative operating conditions with dilute phase often include a catalyst / gas mixture with a density between 15 and 150 kg / m3. Figure 1 shows an FCC unit using a vertical concentric column and a demetallization tank. A regenerator pipe 16 transfers catalyst from a regenerator 10 at a rate regulated by a slide valve 11. A fluidization medium from a nozzle 17 transports catalyst up a vertical column 14 at a relatively high density until a plurality of nozzles Feed injection 15 (only one shown) injects feed through the stream of catalyst particles. The resulting mixture continues to climb up the vertical column 14 until a pair of separation extensions 21 tangentially discharge the gas and catalyst mixture from an upper portion 19 of the vertical column 14 through the ports 29 to a separation tank 23 which effects the gas separation of the catalyst. A transport conduit 22 transports the hydrocarbon vapors, which include demetalated hydrocarbons, demetallization medium and catalyst entrained to one or more cyclones 24 in a separator tank 12, that separates spent catalyst from the hydrocarbon vapor stream. A collecting chamber 25 in the separator tank 12 collects the separated streams of hydrocarbon vapor from the cyclones 24 to pass them to an outlet nozzle 20, and eventually to a fractionation zone (not shown). The immersion feet 18 discharge catalyst from the cyclones 24 to a lower portion of the separator tank 12 in a collecting space 31 that eventually passes the catalyst and the hydrocarbons adsorbed or entrained to a demetallization section 32 through the ports 37 defined in a wall 39 of the separator tank 23. The separated catalyst in the separator tank 23 goes directly to the demetallization section 32. Since the separator tank 23 includes the demetallization section 32, it can also be designated as a demetallization tank. The demetallization section 32 contains baffles 35 to promote contact and mixing between a demetallization gas and the catalyst. The deflectors appear as horizontal, although they may have other configurations, such as a frusto-conical shape. The demetallization gas enters a lower portion of the demetallization section 32 through the inlets 33, 34. The inlets 33, 34 can supply the demetallization gas to one or more distributors (not shown) that distribute the gas around of the circumference of the deflectors 35. The spent catalyst leaves the demetallization section 32 through a reactor conduit 36, and passes to the regenerator 10. A regeneration gas, such as compressed air, enters the regenerator 10 through a conduit 30. An air distributor 28 disperses air through the cross section of the regenerator 10, where the spent catalyst contacts. Coke is extracted from the catalyst by combustion with oxygen from the air distributor 28. By-products of the combustion and the unreacted air components together with the catalyst carried by the regenerator 10 rise to the cyclone inlets 26, 27. It accumulates relatively catalyst-free gas in an internal chamber 38 communicating with a gas outlet 40, which draws spent regeneration gas from the regenerator 10. The catalyst separated by the cyclones 26, 27 falls through the discharge extensions 42, 43, and returns to a bed 44 in the lower portion of the regenerator 10. Figure 2 shows an enlarged, partial and perspective view of the demetallization section 32 of Figure 1. Parts of Figure 2 were excluded or opened to fully illustrate the section of demetallization 32 of the present invention. The spent catalyst enters the demetallization section 32 through an upper part 23a of the separating tank 23 or through the ports 37 of the collecting space 31. The demetallized hydrocarbons and medium demetallisation exit from the top of the separator tank 23. Each baffle 35 is supported in the demetallization section 32 by an inclined support structure 50. The inclined support structure 50 may comprise an outer circular band 52 and an inner circular band 54. The outer circular band 52 is connected to the inner circular band 54 by elongated bars or rays 56 that exit the inner circular band 54 to the outer circular band 52. Each end of each ray 56 is secured with the outer circular band 52 and the outer circular band 52. inner circular band 54. The outer circular band 52 is secured with the wall 39 of the separator tank 23, which contains the demetallization section 32, or the inner circular band 54 is secured with the outer wall 13 of the vertical column 14 that extends by the demetallization section 32 and the remainder of the separator tank 23. In a mode that does not include an internal vertical column in or of the demetallization section 32, the spokes may extend diametrically through the outer circular band 52, and only one end of each ray 56 could be secured to the outer circular band 52. The other end of the beam 56 could be separated from the wall 39. This embodiment would avoid the need for the inner circular band 54. Each baffle 35 comprises several sectors comprising a perforated section 60 and a non-perforated section. perforations 62. Perforated section 60 may be comprised of circular openings in a plate, or may comprise a grid. In one embodiment, the openings in the baffle are large enough to allow catalyst particles to pass. The non-perforated section 62 could be a portion of the plate comprising a baffle sector 58 without openings, or it can comprise a non-perforated plate placed over the perforated section 60 of the baffle sector 58. Each side edge of the baffle sector 58 can include a skirt wall 64 that hangs down from the sector. In one embodiment, all adjacent baffle sectors 58 are typically separated from each other as consistent degrees, and adjacent edges of adjacent baffle sectors 58 define down tubes or down tube sections 66. Adjacent baffles 35 are disposed about the height of the baffle. Demetallization section 32 with alternating orientations. Accordingly, the down tube section 66 of an overlying baffle 35 is vertically aligned with the non-perforated section 62 of an underlying baffle 35. This arrangement, in which the down tube section 66 and the non-perforated section 62 are aligned, and by diverting sections of the down tube 66 from the adjacent deflectors 35, ensures the horizontal movement of the catalyst on the surface of the deflectors 35, particularly on the deflector sectors 58. Although the catalyst falls through the openings in the perforated section 60 of each baffle sector 58, most of the catalyst falls through the falling tube section 66. Accordingly, the perforated plate, vertically aligned with the descending tube sections 66 of the overlying deflector 35, it prevents the catalyst from falling vertically through all deflector sections without having any horizontal movement. In one embodiment, the height of the separation between each successive tray is between 31 and 76 cm. In another embodiment, the height of the separation between successive trays is 61 cm, although it may be preferable to reduce the height to 46 cm, to place more baffles in the demetallization section 32. If all baffles 35 were shown in Figure 2 , nine deflectors 35 would appear. Figure 3 is a cross-sectional view of Figure 2 taken on segment 3-3. Figure 3 shows the vertical column 14 and eight baffle sectors 58 comprising the baffle 35. Each baffle sector 58 has an inner circular edge 58a, an outer circular edge 58b and radial edges 58c, 58d. The inner circular edge 58a rests on an upper projection 54a of the inner circular band 54, and the outer circular edge 58b rests on an upper projection 52a of the outer circular band 52.

The inner circular edge 58a defines an arc, which is shorter than the arc defined by the outer circular edge 58b. The non-perforated section 62 covers the beam 56, which is shown in dotted lines, which supports the respective circular band 52, 54 which is not secured with a respective wall 39, 13. The opposite radial edges 58c, 58d of the baffle sector 58 adjacent limits the down tube sections 66. Accordingly, the perforated sections 60 are between the down tube sections 66 in one embodiment. Furthermore, in one embodiment, the non-perforated section 62 is between two perforated sections 60 and two sections of falling tube 66. The skirt walls 64 can extend downward from the radial edges 58c and 58d of each baffle sector 58, but only between the inner circular band 54 and the outer circular band 52. In one embodiment, each baffle sector 58, each non-perforated section 62, or each down tube section 66 arises from the center of the demetallization section 32. In one embodiment , opposite side edges of each deflector sector 58, each section without perforations 62 and each section of falling tube 66 are closer to each other in the direction toward the center of the demetallization section 32 than they are at the periphery of the section of demetallization 32, whereby they are not parallel. When catalyst falls from the pipe section descending 66 of an overlying deflector 3'5, falls on the non-perforated section 62, and propagates angularly and hontally towards the falling tube sections 66. In the eight-deflector section mode, each with a non-perforated section 62 between the two sections of down tube 66, the catalyst falling from an overlying deflector 35 will propagate hontally, generally in 16 angular directions. The perforated section 60 may include numerous openings made in a plate. One embodiment of this invention is the distribution of the deflector openings on the entire surface of the perforated section 60 of the baffles 35. The separation of the perforations on the perforated section 60 can be arranged in any manner that eliminates broad bands or zones that do not contain perforation for the supply of the fluidization medium. The perforation distribution beneficial to this invention can be described by a maximum circular surface containing at least one opening. Generally, any circular surface of at least 0.09 m2 preferably surrounds at least a portion of one or more openings in that surface. The circular area that can be circumscribed without enclosing a hole preferably should not be greater than 0.05 m2. Following this type of criteria for the minimum geometry of a surface that must contain a perforation will facilitate a sufficient fluidization. In one embodiment, the perforated section 60 may comprise a grid 68 defining openings 70, as shown in Figure 3. The grid 68 may comprise a grid of elongated stripes intersecting each other on the long sides of each elongate strip. In another embodiment, the grid 68 may comprise a series of elongated stripes running parallel to a series of parallel or criss-cross rollers resting on the upper part of the elongated strips. Those skilled in the art are very familiar with the various ways of constructing the perforated section 60. However, in one embodiment, the apertures in the perforated section 60 must be large enough to allow significant amounts of catalyst to pass through. This is most easily achieved with the perforated section 60 comprising the grid 68. The term "significant amounts of catalyst" means at least 20% of the weight of the catalyst descending through the openings 70 in each baffle 35. It is estimated that, typically, , up to 60% of the weight of the catalyst will fall through the openings of each baffle 35 including the grid 68 for the perforated section 60. The remainder of the catalyst will descend the down tube sections 66 of each baffle 35. In one embodiment, when less 35% of the surface of the section perforated 60 comprises openings large enough to allow the passage of catalyst particles and demetallization medium, and small enough to decrease the formation of large gas bubbles under the baffle 35. In one embodiment, the demetallization fluid phase must rise by the openings without significant obstacles. In this way, the speed of the demetallization fluid through the openings should be no more than 0.15 m / s. An opening dimension of between 1.0 and 1.3 cm is adequate. In addition, vapor velocities of between 0.015 and 0.6 m / s, and vapor flows of between 0.5 and 3.0 kg of vapor / kg of catalyst will be suitable for the present invention. The non-perforated section 62 may comprise a plate, which in one embodiment rests on the perforated section 60 of the baffle 35. The plate comprising the section without perforations 62 may be secured with the perforated section 60. The plate may rest on the perforated section 60, and may comprise a sloped top surface or two inclined top surfaces for directing the catalyst and drainage. In one embodiment, the cross section of the demetallization section 32 and each baffle 35 is divided into eight baffle sectors 58 of equal surfaces. Each baffle sector 58 may comprise 36 ° of partially open baffle surface comprising the sections perforated and without perforations 60, 62, and 9 ° of section descending tube 66 completely open. In one embodiment, the non-perforated section 62 comprises 9 °, and the perforated section 60 comprises 27 ° of each baffle sector 58. In another embodiment, instead of using the rays 56 to support the baffles, the inner and outer edges of the skirt walls 64 can be secured with the outer circular band 52 and the inner circular band 54, respectively. Then, the outer circular band 52 or the inner circular band 54 can be secured with the wall 39 and the wall 13 of the vertical column 14. In another embodiment, a baffle configuration can be provided in a demetallization tank that does not include a internal vertical column 14. Other support structures may also be acceptable. In one embodiment, the deflectors are typically formed with alloy steels that withstand high temperature conditions in the reaction zone. These steels are often subject to erosion, and the baffles could benefit from the use of inserts or nozzles to define the openings, and provide resistance to the erosive conditions imposed by the circulation of catalyst on the upper part of the baffle. In addition, deflectors are routinely covered with a refractory material that provides additional resistance to erosion. The details of abrasion resistant nozzles and refractory liners are known to those skilled in the art of particle transport.

Claims (10)

1. CLAIMS 1. A device for demetallizing hydrocarbons of particulate material, wherein the device comprises: a demetallization tank; at least one port defined by the demetallization tank for receiving particles containing hydrocarbons, and for extracting demetallization fluid and demetalated hydrocarbons from the demetallization tank; a plurality of demetallization baffles vertically spaced apart from each other on at least a portion of the demetallization tank, wherein one of the plurality of baffles includes at least three descending tubes extending radially from a vertical center of the demetallization tank; a plurality of openings distributed over at least a portion of the surface of at least one of the demetallization baffles; at least one fluid inlet for passing a demetallization fluid to a bottom side of the at least one of the demetallization baffles for demetallizing hydrocarbons from the particulate material; and at least one particle outlet (36) for recovering demetallized particles from the demetallization baffles. The device of claim 1, characterized in that the at least three descending tubes are bounded by opposite non-parallel sides. 3. The device of claim 1 or 2, characterized in that one of the demetallization baffles is horizontal. The device of claim 1, 2 or 3, characterized in that the deflector further comprises a section without perforations and a perforated section, wherein the perforated section includes the plurality of openings. The device of claim 1, 2, 3 or 4, characterized in that the section without perforations is disposed between two of the descending tubes. The device of claim 1, 2, 3, 4 or 5, characterized in that the perforated section is disposed between the down tube and the non-perforated section. The device of claim 1, 2, 3, 4, 5 or 6, characterized in that a conduit extends through the demetallization tank, and the demetallization baffle is at least indirectly supported by the conduit. The device of claim 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that the demetallizing baffle comprises a grid. 9. A process for demetallizing hydrocarbons from particulate material, wherein the process comprises: feeding hydrocarbon-containing particles to a tank that includes a plurality of demetallization baffles vertically separated, wherein one of the plurality of baffles includes a downward tube extending radially from a center of the demetallization tank, where the down tube is bounded by opposite and non-parallel sides, and a plurality of openings distributed over at least one section of the surface of the at least one of the demetallization baffles; passing a demetallization fluid to a lower side of one of the demetallization baffles to demetallize hydrocarbons from the particulate material; recover demetallization fluid and demetallized hydrocarbons from the tank; and collect de-metallized catalyst from the tank. The process of claim 9, wherein the baffle comprises at least three down tubes.