FR3104467A1 - Device and process for gas-solid separation of catalytic cracking in fluidized bed with deflector under window - Google Patents

Abstract

Device and a method for separating and stripping a gas mixture and solid particles comprising a plurality of separation (12) and pre-stripping (13) chambers distributed around a central reactor (14), each pre-stripping chamber ( 13) comprising a peripheral wall (25), two substantially vertical side walls (20) which are also the side walls of the separation chambers (12), a lower inlet opening (24) for stripping gas adapted to communicate with a stripping chamber (23), and an upper outlet opening (31) for the gas mixture and stripping gas adapted to communicate with a second separation stage, in which a baffle (28) is disposed between the stripping chamber (23) ) and the pre-stripping chamber (13) and is adapted to deflect the ascending stripping gas and forcing said stripping gas to have at least one substantially horizontal movement. Figure 4 to publish

Description

Device and process for the gas-solid separation of catalytic cracking in a fluidized bed with a deflector under a window

The invention relates to the field of refining and petrochemistry and processes and devices for the chemical transformation of petroleum products, in particular crude petroleum by fluidized bed catalytic cracking (“fluid catalytic cracking” or FCC according to the Anglo-Saxon terminology). .

An FCC unit is conventionally used in refining to convert a heavy feed, characterized by a temperature at the start of boiling close to 340°C, often above 380°C, into lighter products that can be used as fuels, in particular gasoline. , the first product of an FCC unit, characterized by temperatures at the start of boiling close to ambient and by temperatures at the end of boiling of 160°C or even 220°C depending on whether we are talking about light gasoline or not.

Figure 1 shows a reference FCC unit diagram. A charge 1 sprayed in the form of fine drops is introduced at the bottom of an ascending gas-solid entrained bed reactor 2 ("riser" according to the Anglo-Saxon terminology; hereinafter referred to as central reactor) where it is mixed with a source of solid catalyst 3 coming from a regenerator 4. At the head of the central reactor 2, the gas/solid mixture is separated in a separation chamber 5 comprising in particular an internal separator 6. At the outlet of the internal separator 6, a gas is directed towards a second stage of separation (cyclone 7) in order to eliminate the fine solid particles present in the gas. Solid particles (i.e., coked catalyst) from the internal separator 6 are also distributed to a stripping chamber 8, in which the solid particles are brought into countercurrent contact with a stripping gas in order to release the potential hydrocarbons that have remained adsorbed on the surface of the coked catalyst. The stripping gas and the desorbed hydrocarbons join the previously separated gas while the coked catalyst is withdrawn continuously at the bottom of the stripping chamber 8. The coked catalyst is then directed towards the base of the regenerator 4 where the exothermic combustion of the coke regenerates and heats the catalyst. Finally, the regenerated and heated catalyst is reinjected into the bottom of central reactor 2 in order to maintain the catalytic cracking reactions.

Patent FR2767715 describes a first separation enclosure for an FCC unit developed by IFP Energies nouvelles. With reference to FIG. 2, the internal separator of the separation enclosure comprises an envelope 111 containing separation chambers 112 and prestriping chambers 113, distributed axially around an upper end of a central reactor 114, the chambers separation chamber 112 and the prestriping chambers 113 being arranged alternately around the central reactor 114. Each separation chamber 112 comprises in its upper part an upper inlet opening 115 communicating with the central reactor 114 and disposed between an upper wall 116 and a lower wall 117 of the separation chamber 112. The upper wall 116 and the lower wall 117 being substantially horizontal at their junction with the central reactor 114, these then curve downwards to become an outer wall 118 and an inner wall 119 substantially vertical, respectively, the curvature delimiting a winding or centrifugation zone for the rotation in a vertical plane of the gas-particle reaction mixture. Each separation chamber 112 further comprises two vertical side walls 120 which also form the walls of the prestriping chambers 113. At least one of the vertical side walls 120 of each separation chamber 112 comprises a side outlet opening 121 below the upper inlet opening 115 to send gas and unseparated solid particles into the adjacent prestriping chamber 113. Each separation chamber 112 further comprises a lower axial outlet opening 122 of the solid particles towards a stripping chamber 123 ("stripper" according to the English terminology) arranged below the internal separator and comprising at least one gas inlet of stripping. Similarly, each prestripping chamber 113 comprises in its lower part a lower inlet opening 124 letting in the ascending stripping gas. Finally, the internal separator further comprises an upper gas evacuation duct 125 connected to the prestriping chamber 113 via an upper outlet opening and connected to a stage of cyclones (not shown) arranged above the internal separator, the stripping chamber 123 communicating mainly with the cyclone stage via the prestriping chambers 113 and the upper evacuation conduit 125.

Patent FR2894842 describes a second separation enclosure for an FCC unit developed by IFP Energies nouvelles in which the lower end of each prestriping chamber comprises an oblique descending wall fixed to the internal wall of the casing.

Application US20180216012 describes a third separation enclosure similar to the separation enclosures of IFP Energies nouvelles, in which the separation chambers of the internal separator are connected to each other by means of a return leg ("dipleg" according to the terminology common Anglo-Saxon), the common return leg of said separation chambers comprising descending solid particle baffles to reduce re-entrainment of the catalyst in the separation chambers.

Since non-separated solid particles can be entrained from the separators of the prior art towards the cyclone stage, a first object of the present description is to reduce the entrainment of solid particles in the prestriping chambers, and thus contribute to increase the efficiency of the gas/solid separators of the FCC units. To this end, a separation and stripping device and method capable of deflecting the stripping gas (coming from the stripping chamber) by causing it to have at least one horizontal movement between the stripping chamber and the prestripping chamber , is described below.

According to a first aspect, the present invention relates to a device for separating and stripping a gaseous mixture and solid particles comprising a plurality of separation chambers and a plurality of prestriping chambers distributed alternately around a central reactor, wherein each separation chamber comprises: an outer wall; an upper inlet opening for the gaseous mixture and the solid particles adapted to communicate with the central reactor; a lower axial outlet opening for the solid particles adapted to communicate with a stripping chamber arranged below the separation chamber; and two substantially vertical side walls which are also the side walls of the prestriping chambers, at least one of the side walls of each separation chamber comprising a side opening for the outlet of the gas mixture, communicating with an adjacent prestriping chamber, and in which each prestriping chamber comprises: a peripheral wall; a lower stripping gas inlet opening adapted to communicate with the stripping chamber; and an upper outlet opening for the gas mixture and the stripping gas adapted to communicate with a second separation stage, the separation and stripping device further comprising a deflector arranged between the stripping chamber and the prestripping chamber adapted to deflect the ascending stripping gas and constraining said stripping gas to have at least one substantially horizontal movement.

According to one or more embodiments, the deflector is adjacent to the lower entry opening of the prestriping chamber.

According to one or more embodiments, the deflector is positioned directly under the lower inlet opening of the prestriping chamber.

According to one or more embodiments, the deflector comprises a substantially horizontal main body.

According to one or more embodiments, the main body has an angle β of between 60° and 120° relative to the central axis of the central reactor.

According to one or more embodiments, the main body is fixed to the outer wall of the central reactor and/or to at least one of the substantially vertical side walls of the separation chambers.

According to one or more embodiments, the peripheral wall comprises a conical lower part in the form of an oblique wall descending inwards, and the main body has a crown portion shape, the major radius of which is equal to or greater than to the radius of the inner end of the descending oblique wall.

According to one or more embodiments, the entry surface between the descending oblique wall and the deflector is substantially equal to the entry surface of the lower entry opening.

According to one or more embodiments, the deflector comprises an upwardly extending flange being disposed on the outer end of the main body.

According to one or more embodiments, the rim extends outwards and has an angle of between 0° and 60° with respect to the central axis of the central reactor.

According to one or more embodiments, the peripheral wall comprises a conical lower part in the form of an oblique wall descending inwards, and the upper end of the rim is at a height substantially equal to or greater than the height of the internal end of the descending oblique wall.

According to one or more embodiments, at least a part of the deflector comprises a packing or a perforated plate.

According to a second aspect, the present invention relates to a separation chamber of a fluidized bed catalytic cracking unit comprising the separation and stripping device according to the first aspect.

According to a third aspect, the present invention relates to a fluidized bed catalytic cracking unit comprising the separation and stripping device according to the first aspect or the separation enclosure according to the second aspect.

According to a fourth aspect, the present invention relates to a process for separating and stripping a gaseous mixture and solid particles using the separation and stripping device according to the first aspect, the separation enclosure according to the second aspect, or the A fluidized bed catalytic cracking unit according to the third aspect, said method comprising deflecting rising stripping gas between the stripping chamber and the prestripping chamber and causing said stripping gas to have at least one substantially horizontal motion. Advantageously, the rising stripping gas is deflected by the deflector to constrain said stripping gas to have at least one substantially horizontal movement.

Other characteristics and advantages of the invention of the aforementioned aspects will appear on reading the description below and non-limiting examples of embodiments, with reference to the appended figures and described below.

List of Figures

Figure 1 shows a schematic of a reference FCC unit.

Figure 2 shows a perspective view of a separation enclosure of a reference FCC unit.

Figure 3 shows a vertical section A of separation chambers of a separation and stripping device according to the present invention.

FIG. 4 shows a vertical section B of prestripping chambers of a separation and stripping device according to the present invention.

Figure 5 shows a top view of a cross-section C of the separation chambers and the prestripping chambers of a separation and stripping device according to the present invention.

FIG. 6 shows a vertical section of simplified reference stripping and prestripping chambers, with a single vertical opening between said chambers.

Figure 7 shows a vertical section of simplified stripping and prestripping chambers, with opening provided with a deflector according to the present invention.

Figure 8 shows 3D CFD simulation estimates of solid particle entrainment in the simplified stripping and prestriping chambers of Figure 6.

Figure 9 shows the 3D CFD simulation estimates of solid particle entrainment in the simplified stripping and prestriping chambers of Figure 7.

The dotted arrows in the figures represent the fluidic flow (gas and particles).

Detailed description of the invention

Embodiments of the device according to the first aspect will now be described in detail. In the following detailed description, many specific details are exposed in order to provide a more in-depth understanding of the device. However, it will be apparent to those skilled in the art that the device can be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

In what follows, the term "understand" is synonymous with (means the same as) "include" and "contain", and is inclusive or open-ended and does not exclude other non-recited elements. It is understood that the term “include” includes the exclusive and closed term “consist”.

The device for separating and stripping a gaseous mixture and solid particles according to the present invention is applicable to gas/solid separation units, and more particularly to the internal separators of the separation enclosures of FCC units.

Referring to Figures 3, 4 and 5, the separation and stripping device according to the present invention comprises a plurality of separation chambers 12 and a plurality of pre-stripping chambers 13 distributed alternately around (e.g. the upper end) a central reactor 14, of substantially vertical and elongated shape (e.g. tubular), closed by an upper section, and in which the gaseous mixture and the solid particles to be separated circulate.

According to one or more embodiments, the separation and stripping device according to the present invention is an internal separator placed in the casing 11 of a separation chamber 10 of an FCC unit.

The load from the central reactor 14 is generally a heavy load, characterized by a boiling onset temperature close to 340° C., often greater than 380° C., such as a heavy cut, for example from a distillation unit under vacuum, such as vacuum gas oil ("vacuum gas oil" or "VGO" according to the Anglo-Saxon terminology), a vacuum residue, a coking gas oil, a recycle from a hydrocracking step, alone or in blend. In contact with the hot solid catalyst, the pulverized charge vaporizes and endothermic cracking reactions occur along the central reactor 14 thus reducing the temperature and producing recoverable products (eg C ₁ -C ₄ gas; a gasoline cut; a light diesel cut ("Light Cycle Oil" or LCO according to the English terminology); a heavy diesel cut ("Heavy Cycle Oil" or HCO according to the English terminology); and a slurry oil ("slurry" according to the Anglo-Saxon terminology)) and a solid residue (coke) adsorbed on the catalyst (hereinafter called solid particles). According to one or more embodiments, the operating conditions of the central reactor 14 are as follows: superficial gas velocity: between 3 and 35 m/s; temperature: between 500 and 700°C and preferably below 650°C; pressure: between 0.1 and 0.6 MPaa; contact time less than 1 second; and a mass ratio of the catalyst to the charge C/O: between 3 and 50.

According to one or more embodiments, the chambers of the same type, separation 12 or prestriping 13, generally have the same dimension, in particular a horizontal section with the same opening angle with respect to the central axis Z of the reactor central 14. According to one or more embodiments, the separation 12 and prestriping 13 chambers have the same dimension, in particular a horizontal section with the same opening angle with respect to the central axis Z of the central reactor 14 According to one or more embodiments, the separation chambers 12 and/or the prestriping chambers 13 have horizontal sections with different opening angles. According to one or more embodiments, there is an axial symmetry of the chambers around the central axis Z of the central reactor 14. According to one or more embodiments, the number of separation chambers 12 varies between 1 and 8, preferentially between 2 and 4. According to one or more embodiments, the number of prestriping chambers 13 varies between 1 and 8, preferably between 2 and 4. According to one or more embodiments, the number of separation chambers 12 and the number of prestriping chambers 13 are identical. The separation chambers 12 and the central reactor 14 form a first integral assembly. The prestriping chambers 13 are delimited by a peripheral wall and the external wall of the central reactor 14. It should be noted that the envelope 11 extends beyond the angular sector corresponding to the separation chambers 12 and prestriping 13 of such so that the outer/peripheral walls of the separation 12 and prestriping 13 chambers are contained within the outer casing 11.

Each separation chamber 12 comprises in its upper part an upper inlet opening 15 communicating with the central reactor 14 and arranged between an upper wall 16 and a lower wall 17 substantially (e.g. ± 10°) horizontal at their junction with the central reactor 14. The gas stream loaded with solid particles from the central reactor 14 passes entirely into the separation chambers 12 via the upper inlet openings 15, because the central reactor 14 has a closed upper section located substantially at or at -above the top of the upper inlet openings 15, i.e., at or above the substantially horizontal upper wall 16.

According to one or more embodiments, each separation chamber 12 further comprises a centrifugation zone making it possible to separate the solid particles from the gaseous mixture by means of the upper wall 16 and the lower wall 17, these curving towards the bottom to become an external wall 18 and an internal wall 19 substantially (e.g. ± 10°) vertical, respectively, the curvature delimiting the centrifugation zone. The centrifugation zone is defined so as to allow the rotation (see dotted arrows in FIG. 3) in a substantially vertical plane (i.e., vertical section A) of the gaseous mixture and the solid particles. The solid particles having a substantially vertical and upward movement at the outlet of the central reactor 14 are found at the outlet of said centrifugation zone with a substantially vertical and downward movement.

Each separation chamber 12 comprises (is delimited by) an outer wall 18 placed between the casing 11 and the central reactor 14, an inner wall coinciding with the outer wall of the central reactor 14, and two side walls substantially (e.g. ± 10° 20 which also form the substantially vertical side walls 20 of the prestriping chambers 13. At least one of the substantially vertical side walls 20 of each separation chamber 12 comprises a side outlet opening 21 arranged below the inlet opening upper 15 (e.g. (directly) below the substantially horizontal lower wall 17 and between the substantially vertical internal wall 19 and the external wall of the central reactor 14) adapted in particular to distribute the gaseous mixture and optionally non-separated solid particles towards a adjacent prestriping chamber 13. According to one or more embodiments, the lateral outlet opening 21 extends vertically at least up to the lower edge of the substantially vertical internal wall 19 of the separation chamber 12, and/or up to a dimension corresponding substantially (e.g. ± 10%) to the largest diameter of the substantially vertical outer wall 18 of the separation chamber 12. The lower edge of the lateral outlet opening 21 is preferably located at a level greater than or equal to the lower edge of the wall substantially vertical internal 19.

According to one or more embodiments, the substantially horizontal upper wall 16 of the separation chamber 12 preferably curves up to a diameter D1 of the outer wall 18, then the substantially vertical outer wall 18 is preferably extended by a vertical and/or conical portion up to a diameter D2 less than or equal to diameter D1, then is optionally extended further by a substantially (e.g. ± 10°) vertical end portion called the return leg. According to one or more embodiments, the length of the vertical and/or conical portion of the outer wall 18 is greater than or equal to the length of the inner wall 19.

Each separation chamber 12 further comprises in its lower part, a lower axial outlet opening 22, for example to send the separated solid particles to a stripping chamber 23 (e.g. of a separation enclosure of an FCC unit) arranged below the separation chamber 12 (and the prestriping chamber 13), the solid particles contacting a stripping gas (e.g. steam) in countercurrent in the stripping chamber. Specifically, the lower end of the substantially vertical outer wall 18, in combination with the outer wall of the central reactor 14 and the lower ends of the vertical side walls 20 define the lower axial exit opening 22 and allow a downward substantially axial exit of the solid particles contained in the separation chamber 12. Thus, the lower axial outlet opening 22 is located below the lateral outlet opening 21.

According to one or more embodiments, the stripping chamber 23 comprises means for standardizing the flow of solid particles located in the upper part of said stripping chamber 23, making it possible in particular to promote contact between said solid particles and the stripping gas. These means favoring the standardization of the flow of solid gas can be inclined plates arranged in baffles, packings (“packing” according to the English terminology) optionally structured or other means of which a non-limiting description can be found in patents US 2440620, US2472502, US 2481439 or US 6224833 or in books such as "material and equipment", volume 4 of the encyclopedia oil refining, by P. Trambouze published by Technip, 1999.

With reference to FIGS. 4 and 5, each prestriping chamber 13 comprises a peripheral wall 25. According to one or more embodiments, the peripheral wall 25 comprises an upper part of spherical or ovoid section 26 extended downwards by a central part of vertical section. According to one or more embodiments, the upper part of the peripheral wall 25 does not comprise an upper part of spherical or ovoid section 26 and comprises (only) an upper part of vertical section (not shown). According to one or more embodiments, the vertical central part is extended by a conical lower part in the form of an oblique wall 27 descending inwards ( ie, towards the Z axis). According to one or more embodiments, the peripheral wall 25 is fixed to the substantially vertical side walls 20. According to one or more embodiments, the descending oblique wall 27 has an angle α of between 5° and 60° with respect to the central axis Z of the central reactor 14. According to one or more embodiments, the descending oblique wall 27 has an angle α of between 10° and 45° relative to the central axis Z of the central reactor 14. According to one or more embodiments embodiment, the descending oblique wall 27 has an angle α of 15° (eg ± 3°) with respect to the central axis Z of the central reactor 14.

Each prestriping chamber 13 further comprises in its lower part, a lower inlet opening 24 letting in the ascending stripping gas, in order to communicate in particular with the stripping chamber 23, and being defined for example by the lower end of the descending oblique wall 27, the two substantially vertical side walls 20, and the outer wall of the central reactor 14.

The separation and stripping device according to the present invention comprises a deflector 28 for deflecting the ascending stripping gas and constraining said gas to have at least a substantially (e.g. ± 20°, preferably ± 10°, preferably ± 5°) horizontal movement . Advantageously, the deflector 28 makes it possible to reduce the entrainment of the solid towards the prestriping chambers 13, and thus contribute to increasing the separation efficiency of the separation enclosure.

Referring to Figures 4 and 5, the deflector 28 is disposed between the stripping chamber 23 and the prestriping chamber 13. According to one or more embodiments, the deflector 28 is adjacent to the lower inlet opening 24 of the prestriping chamber 13. According to one or more embodiments, the deflector 28 is positioned directly under the lower inlet opening 24 of the prestriping chamber 13. Advantageously, the deflector 28 makes it possible to induce, with the ascending stripping gas from the stripping chamber 23, a substantially horizontal movement before entering the prestriping chamber 13 and thus reduce the entrainment of the catalyst particles.

According to one or more embodiments, the deflector 28 comprises a substantially horizontal main body. According to one or more embodiments, the deflector 28 comprises a substantially planar plate. According to one or more embodiments, the main body has an angle β of between 60° and 120°, preferably between 70° and 110°, preferably between 80° and 100° (e.g. 90° ± 3°), relative to the central axis Z of the central reactor 14.

According to one or more embodiments, the main body has the shape of a crown portion, the small radius of which is equal to or greater than the radius of the external wall of the central reactor 14. According to one or more embodiments, the main body is attached to the outer wall of the central reactor 14 and/or to at least one of the substantially vertical side walls 20 of the separation chambers 12. According to one or more embodiments, the main body has the shape of a crown portion, the large radius is equal to or greater than the radius of the internal end of the descending oblique wall 27. According to one or more embodiments, the main body has the shape of a crown portion, the large radius of which is at least 1.1 times greater to the radius of the inner end of the descending oblique wall 27. According to one or more embodiments, the main body has the shape of a crown portion, the major radius of which is between 1.2 and 1.5 times, preferably between 1.3 and 1.4 times, the radius of the inner end of the descending oblique wall 27. According to one or more embodiments, the entry surface between the descending oblique wall 27 and the deflector 28 is substantially ( ±10%, preferably ±5%) equal to the entrance area of the lower entrance opening 24.

According to one or more embodiments, at least a part of the deflector 28 comprises a packing or a perforated plate adapted in particular to deflect the stripping gas and allow the descending non-separated solid particles to evacuate, for example to avoid any accumulation of catalyst on deflector 28.

According to one or more embodiments, the deflector 28 comprises a flange 29 extending upwards and being disposed on the outer end of the main body. Advantageously, the rim makes it possible to constrain the descending non-separated solid particles to be evacuated mainly by the packing or the perforated plate. According to one or more embodiments, the rim 29 extends upward and outward. According to one or more embodiments, the flange 29 is in the form of a plate presenting an angle comprised between 0° and 60°, preferably between 5° and 45°, preferably between 10° and 30°, with respect to the central axis Z of the central reactor 14. According to one or more embodiments, the flange 29 is in the form of a plate having an angle of 15° (e.g. ± 3°) with respect to the central axis Z of the central reactor 14. According to one or several embodiments, the upper end of the flange 29 is at a height substantially (e.g. ± 10 cm) equal to or greater than the height of the internal end of the descending oblique wall 27. Advantageously, the flange makes it possible to constrain the gas upward stripping to have at least one downward movement between the deflector 28 and the downward oblique wall 27.

The separation and stripping device further comprises an upper evacuation conduit 30 for the gaseous effluents leaving the prestriping chambers 13, for example to send the gaseous effluents (gaseous mixture and stripping gas) to at least one second stage of separation (e.g. a cyclone stage) of a separation enclosure of an FCC unit, the stripping chamber 23 communicating with the upper evacuation conduit 30 via the prestriping chambers 13. According to one or more embodiments, the conduit upper evacuation 30 of the gaseous effluents coming from the prestriping chambers 13 is located substantially along the axis of the central reactor 14, and is connected on the one hand to said prestriping chambers 13 by upper outlet openings 31, and on the other hand to the second stage of separation (not shown), making it possible in particular to separate the residual solid particles contained in the gaseous effluents coming from the upper evacuation conduit 30. According to one or more embodiments, each cyclone of the second separation stage comprises a gaseous effluent outlet, and a solid particle outlet plunging into the stripping chamber 23.

According to one or more embodiments, the difference in thermal expansion between, on the one hand the central reactor 14 and the separation chambers 12 forming the first integral assembly, and on the other hand the prestriping chambers 13 forming a second assembly, is compensated by interstices separating the two sets. According to one or more embodiments, the thermal expansion between, on the one hand the central reactor 14 and the separation chambers 12, and on the other hand the prestriping chambers 13 is compensated by an expansion joint.

According to one or more embodiments, the separation and stripping device according to the present invention is provided so that the sum of the sections of the side outlet openings 21 of the separation chambers 12 has substantially (e.g. ± 10%) the same value that the sum of the sections of the upper inlet openings 15, and/or that the sum of the sections of the upper outlet openings 31 of the prestriping chambers 13 has substantially the same value as the sum of the sections of the upper inlet openings 15.

In operation, according to one or more embodiments, the gaseous mixture and the solid particles leave the central reactor 14 and enter the separation chamber 12, in which the solid particles are separated and are directed towards the stripping chamber 23 and the gas mixture is directed to the prestriping chamber 13. In the prestriping chamber 13, the gas mixture is entrained towards the second separation stage by an ascending stripping gas distributed by the stripping chamber 23. The gas flow entering the second separation stage is separated from residual solid particles which are directed to the stripping chamber 23 by means of return legs. The gas stream is then evacuated to a gaseous effluent outlet. Finally, the solid particles are stripped of residual gas in the stripping chamber 23 and are discharged through a stripped catalyst outlet to a regenerator (not shown).

The separation and stripping device according to the invention can operate by observing the following operating conditions:

• gas velocity at the head of central reactor 14 from 2 m/s to 35 m/s, preferably from 5 m/s to 35 m/s, preferably from 10 m/s to 25 m/s;
• gas velocity in the upper inlet openings 15 from 2 m/s to 35 m/s, preferably from 5 m/s to 35 m/s, preferably from 10 m/s to 25 m/s;
• gas speed in the side outlet openings 21 from 2 m/s to 35 m/s, preferably from 5 m/s to 35 m/s, preferably from 10 m/s to 25 m/s;
• gas velocity in the lower inlet openings 24 from 0.25 to 5 m/s, preferably from 0.3 m/s to 5 m/s, preferably from 1 m/s to 4 m/s; And
• flow of catalyst in the lower axial outlet opening 22 of between 10 and 300 kg/(m ² .s), preferably from 50 to 200 kg/(m ² .s), with for example solid particles characterized by a mass grain volume of between 1000 and 2000 kg/m ³ , and an average so-called "Sauter" diameter of between 40 and 100 microns.

FIG. 6 and FIG. 7 show a vertical section of stripping and prestriping chambers, reference with simple vertical opening between said chambers (case no. 1), and according to the invention with opening provided with a deflector (case no. °2: representing a simplified configuration of Figures 4 and 5), respectively.

Figures 8 and 9 represent respectively the estimates by 3D CFD simulation of the entrainment of particles in a fluidized bed reactor with a simple vertical fluid outlet as represented in figure 6 (case n°1) and a fluid outlet inducing a horizontal movement of the fluid using a deflector as shown in Figure 7 (case 2).

Numerical simulations are performed with CPFD Barracuda® software. The geometric data of the simulation and the operating and boundary conditions are indicated below:

• simulation at ambient temperature and atmospheric pressure in the presence of air,
• diameter of the reactor Dr = 0.3 m, outlet diameter Ds = 0.106 m, total height of the reactor Htot = 1 m, outlet height Hs = 0.25 m,
• bed height Hbed = 0.3 m for an initial quantity of solid of 17.4 kg,
• input condition: gas velocity of 0.25 m/s,
• exit condition: atmospheric pressure, surface defined in order to have an exit gas velocity of 2 m/s,
• in this example case #2, the area of the annular space is greater than the exit area (the area of the annular space can be less than or equal to the exit area).

The entrainment flow corresponds to the particles elutriated out of the reactor. The flow rate value is averaged over a simulation time of 40 s.

Estimate by CFD of the average entrainment rate:

• case 1: 12.9 kg/h;
• case 2: 4.19 kg/h.

Consequently, the present invention makes it possible to divide by 3 the solid entrainment coming from the stripping chamber and heading towards the prestriping chamber.

Claims (15)

Device for separating and stripping a gaseous mixture and solid particles comprising a plurality of separation chambers (12) and a plurality of pre-stripping chambers (13) distributed alternately around a central reactor (14),
wherein each separation chamber (12) comprises:
- an outer wall (18);
- an upper inlet opening (15) for the gaseous mixture and the solid particles adapted to communicate with the central reactor (14);
- a lower axial outlet opening (22) for the solid particles adapted to communicate with a stripping chamber (23) arranged below the separation chamber (12); And
- two substantially vertical side walls (20) which are also the side walls of the prestriping chambers (13), at least one of the side walls (20) of each separation chamber (12) comprising a side outlet opening (21) of the gas mixture, communicating with an adjacent prestriping chamber (13), and
wherein each prestriping chamber (13) comprises:
- a peripheral wall (25);
- a lower stripping gas inlet opening (24) adapted to communicate with the stripping chamber (23); And
- an upper outlet opening (31) for the gas mixture and the stripping gas adapted to communicate with a second separation stage,
the separation and stripping device further comprising a baffle (28) disposed between the stripping chamber (23) and the prestriping chamber (13) adapted to deflect the ascending stripping gas and to constrain said stripping gas to have at least a substantially horizontal movement. A separating and stripping device according to claim 1, wherein the deflector (28) is adjacent to the lower inlet opening (24) of the prestriping chamber (13). A separating and stripping device according to claim 1 or claim 2, wherein the baffle (28) is positioned directly below the lower inlet opening (24) of the prestriping chamber (13). A separating and stripping device according to any preceding claim, wherein the baffle (28) comprises a substantially horizontal main body. Separating and stripping device according to Claim 4, in which the main body has an angle β of between 60° and 120° with respect to the central axis (Z) of the central reactor (14). Separating and stripping device according to Claim 4 or Claim 5, in which the main body is fixed to the external wall of the central reactor (14) and/or to at least one of the substantially vertical side walls (20) of the separation (12). Separating and stripping device according to any one of Claims 4 to 6, in which the peripheral wall (25) comprises a conical lower part in the form of an oblique wall (27) descending inwards, and in which the main body has a shape of a crown portion, the major radius of which is equal to or greater than the radius of the inner end of the descending oblique wall (27). Separating and stripping device according to claim 7, in which the entry surface between the descending oblique wall (27) and the deflector (28) is substantially equal to the entry surface of the lower entry opening ( 24). Separating and stripping device according to any one of claims 4 to 8, in which the deflector (28) comprises an upwardly extending flange (29) being disposed on the outer end of the main body. Separating and stripping device according to Claim 9, in which the flange (29) extends outwards and has an angle of between 0° and 60° with respect to the central axis (Z) of the central reactor ( 14). Separating and stripping device according to claim 9 or claim 10, in which the peripheral wall (25) comprises a conical lower part in the form of an oblique wall (27) descending inwards, and in which the upper end of the rim (29) is at a height substantially equal to or greater than the height of the inner end of the descending oblique wall (27). A separating and stripping device according to any preceding claim, wherein at least a portion of the baffle (28) comprises a packing or a perforated plate. Separation chamber of a fluidized bed catalytic cracking unit comprising the separation and stripping device according to any one of the preceding claims. Fluidized bed catalytic cracking unit comprising the separation and stripping device according to any one of Claims 1 to 12 or the separation enclosure according to Claim 13. Process for separating and stripping a gaseous mixture and solid particles using the separation and stripping device according to any one of Claims 1 to 12, the separation enclosure according to Claim 13, or the cracking unit The fluidized bed catalytic converter of claim 14, said method comprising deflecting rising stripping gas between the stripping chamber (23) and the prestriping chamber (13) and causing said stripping gas to have at least substantially horizontal motion.