Self-supporting panel for simulated moving bed separation

Abstract

The invention relates to a simulated moving bed, SMB, separation column / method comprising / using a shell (1) which comprises a plurality of adsorbent beds separated by a plurality of trays, each tray comprising a plurality of panels (6), referred to as self-supporting panels, each panel (6) comprising a multi-sided metal frame (7), wherein the metal frame (7) is supported on a first side (13) by the shell and is supported on a second side (14) by: a main beam (3) arranged diametrically in the shell (1); and / or the shell (1) or a central tower (5) arranged in the shell (1), wherein the metal frame (7) comprises at least one third side (15) connecting the first side (13) to the second side (14), and wherein the at least one third side (15) has a height (H) and a thickness that are suitable for ensuring the mechanical strength of the panel.

Description

[0001] Self-supporting panel for simulated moving bed separation

[0002] Technical Field

[0003] The invention relates to the field of separation of natural or chemical products, which are difficult to separate by distillation. A family of processes and associated devices are then used, known as simulated moving bed separation processes or devices, either in simulated counter-current or in simulated co-current, which we will hereinafter refer to as "LMS".

[0004] The areas concerned include the separation of paraxylene from other aromatic C8 isomers. Other areas concerned are, but are not limited to: the separation of normal paraffins from branched paraffins, naphthenes, and aromatics; the separation of olefins / paraffins; the separation of metaxylene from other aromatic C8 isomers; the separation of ethylbenzene from other aromatic C8 isomers; the separation of m-cresol or p-cresol from other cresol isomers.

[0005] Specifically, the invention relates to a device for distributing and collecting fluids within a multi-stage column implementing a flow of said fluids in a medium of solid particles, called an adsorbent bed comprising a granular medium (adsorbent).

[0006] A multi-stage column means a column comprising a plurality of adsorbent beds arranged in series in a flow direction of the fluid(s) used in the column. The fluid successively passing through the adsorbent beds is called the main fluid to distinguish it from other secondary fluids which may be added to the main fluid via the distribution and collection device, also called a tray, generally located between two successive beds (arranged perpendicular to the flow direction of the main fluid).

[0007] A tray comprises at least one collection zone and a distribution and collection network (system of lines and valves) for collecting the main fluid and / or injecting secondary fluids and mixing these secondary fluids with the main fluid. A tray also comprises at least one distribution zone which aims to distribute the fluid resulting from the mixing of the main fluid and the secondary fluids on the granular bed located immediately downstream, in the direction of flow of the main fluid.

[0008] Prior art

[0009] Many devices are known for distributing, mixing or collecting a fluid in an enclosure containing solid particles, such as in particular a multi-stage column. The trays generally have the functions of distributing a fluid as homogeneously as possible over the section of the column, of efficiently mixing the main fluid passing through the different beds of the column with one or more secondary fluids introduced at the level of each bed, possibly of collecting a flow of fluid between two beds, and finally of homogenizing as best as possible the concentrations at the bed outlet before entering the next bed of solid particles, i.e. located immediately downstream of the device in question.

[0010] In addition, the trays must meet a number of constraints such as generating the least possible axial dispersion, generating the minimum pressure loss, and not producing hydrodynamic disturbances that could alter the performance of the process.

[0011] The trays have a number of characteristics common to those skilled in the art.

[0012] For clarity, a multi-stage column is divided into a plurality of Pi trays and Ai adsorbent beds, with the Pi tray being arranged directly upstream of the Ai adsorbent bed, in the direction of flow of the main fluid. In addition, the term Ai+1 adsorbent bed refers to the next adsorbent bed located downstream of the Ai adsorbent bed, in the direction of flow of the main fluid. Similarly, a Pi+1 tray refers to the next tray located downstream of the Pi tray, in the direction of flow of the main fluid.

[0013] In addition, each tray Pi of the column is generally divided into several sectors or regions, called panels. Each panel of the tray comprises a main fluid collection zone and at least one valve for collecting main fluid and / or injecting secondary fluids and mixing these secondary fluids with the main fluid. Each panel also comprises a distribution zone which has the purpose of distributing the fluid resulting from the mixing of the main fluid and the secondary fluids on the granular bed located immediately downstream, in the direction of flow of the main fluid.

[0014] Each panel can have various shapes, the most common being the division into angular sectors or meridian panels, i.e. parallel panels (to each other), of substantially the same width. Current technology generally includes 12 to 16 panels per Pi tray. EP0074815, US2006 / 0108274A1, and FR2708480 provide examples of trays used in the case of LMS adsorption.

[0015] With reference to Figure 1, the multi-stage column comprises a shell 1 in which a plurality of beds of solid particles arranged in series according to a flow direction of a main fluid used in the column. Specifically, the shell 1 comprises, according to the flow direction of the main fluid: a plate Pi-1, an adsorbent bed Ai-1 (called upstream adsorbent bed Ai- 1), a plate Pi, an adsorbent bed Ai (called downstream adsorbent bed Ai), and a plate Pi+1.With reference to Figure 2, the mechanical strength of the plates Pi is ensured by one or more rims 2 arranged radially (perpendicular to the direction of flow of the main fluid) on the inner wall of the shell 1 and a network of beams of two different types: at least one main beam 3 connecting two radially opposite sides of the shell 1 (arranged perpendicular to the direction of flow of the main fluid), adapted to support secondary beams 4; the secondary beams 4 (arranged perpendicular to the direction of flow of the main fluid), oriented perpendicular to the main beams which support the panels; and optionally, a central mast 5 (arranged parallel to the direction of flow of the main fluid, e.g. vertical mast, ie, mounted axially in the shell 1), for example in the form of a tube.

[0016] The central mast 5 generally serves as a support point for the main beam 3 and may include one or more lines of the distribution and collection network.

[0017] With reference to figure 3, the panels 6 can be arranged on the secondary beams 4 according to a meridian cut, for example according to 2 rows of 3 or 4 parallel panels.

[0018] With reference to Figure 4, the panels 6 can be arranged on the secondary beams 4 according to a radial cut, for example around the central mast 5.

[0019] With reference to Figure 5 and Figure 6, the secondary beams 4 make it possible to support: the panels 6 of a Pi tray; and the adsorbent bed Ai- 1 (for a top-down flow) arranged on the Pi tray.

[0020] Referring to Figure 5 and Figure 6, each panel 6 of a tray comprises a metal frame 7 which serves to hold together the elements of the panel 6 (grids and internals), an upper grid 8 and a lower grid 9 to ensure the passage of the main fluid, and distribution and collection internals 10 located between said grids. The distribution and collection internals 10 typically serve to: collect main fluid from an adsorbent bed 11 by a system called a collection baffle or collector; mix main fluid leaving the adsorbent bed 11 with a secondary fluid possibly injected into the panel in question by means of a distribution and collection network, generally ending with an injection-withdrawal box; and redistribute the collected main fluid alone or in mixture with a secondary fluid on the next adsorbent bed 11 by means of a distributor.A multi-stage column is generally between 5 and 10 m in diameter, which means that a panel 6 has a length of up to 5 m and rests on the shell 1 only on one side. The panels 6 must not deform too much under penalty of crushing the screen of the adsorbent bed 11 located below, or even breaking, the mechanical resistance to prevent this deformation is provided by the secondary beams 4, which ensure a deflection of less than 10 mm regardless of the location. On the other hand, the secondary beams 4 reduce the hydrodynamics in the adsorbent bed 11 because the flow 12 of the main fluid is disturbed (reduction of the piston character). On the one hand, it is unfavorable for the main fluid to encounter obstacles, such as the secondary beams 4, at the top of the bed. On the other hand, the surface encountered by the main fluid is increased by the secondary beams 4.

[0021] FR2961112 describes a self-supporting panel to reduce the number of obstacles in the adsorbent bed, the beams being positioned within the distributor panel itself, i.e. between the upper grid and the lower grid. However, the positioning of the beams within the panels themselves hinders the circulation of the fluid inside the panel and reduces the quality of the distribution.

[0022] Summary of the invention

[0023] In the context described above, a first object of the present invention is to improve the flow of fluids during LMS separation inside a multi-stage column, i.e., a column comprising a multiplicity of adsorbent beds arranged in series according to the direction of fluid flow. According to a second object, the present invention makes it possible to reduce the assembly time and to reduce the mass of metal to be used for the construction of the multi-stage column. According to a third object, the present invention makes it possible to improve the homogeneity of the loading of the granular medium in the multi-stage column.

[0024] According to a first aspect, the aforementioned objects, as well as other advantages, are obtained by a simulated moving bed separation column comprising a shell comprising a plurality of adsorbent beds separated by a plurality of trays, each tray comprising a plurality of panels, called self-supporting, each panel being adapted to collect a main fluid coming from an upstream adsorbent bed and to supply a downstream adsorbent bed with the main fluid, each panel comprising a multi-sided metal frame in which are arranged: an upper grid adapted to support a bed of solid particles of the adsorbent bed (eg upstream bed for gravity circulation); liquid distribution and collection internals arranged between the upper grid and a lower grid; and the lower grid, in which the metal frame is supported on a first side by the shell (ega rim or a first rim of the ferrule) and is supported on a second side (eg only) by: a main beam arranged diametrically in the ferrule; and / or the ferrule (eg a rim of the ferrule) or a central mast (eg a rim of the central mast) arranged in the ferrule, in which the metal frame comprises at least a third side connecting the first side to the second side, and in which the at least one third side has a height and thickness suitable for ensuring the mechanical strength of the panel.

[0025] Advantageously, the self-supporting device allows the removal of secondary beams without altering the circulation of fluid inside the panels (which is not the case in particular for the FR2961112 device).

[0026] This innovation has several other additional advantages: improved hydrodynamics, on the one hand because it is more favorable to encounter obstacles at the bottom of the bed, and on the other hand because the surface encountered by the main fluid is smaller; reduced assembly time, since the beams are not installed; reduced mass of metal to be used because the increase in height of a beam is largely favorable to reducing the deflection; improved homogeneity of loading of the adsorbent solid. In current technology, the sieve is loaded by Catapac® and falls from top to bottom. Under the beams, loading is less efficient because the dense loading effect does not take place and only sieve arriving after bouncing on an obstacle reaches the underside of the beams. This results in less dense loading under the beams than elsewhere, which reduces the quality of the hydrodynamics as well as the quantity of loaded sieve.

[0027] According to one or more embodiments, the height and thickness of the third side of the metal frame are chosen to ensure a deflection of less than 15 mm, preferably less than 10 mm, very preferably less than 7 mm.

[0028] According to one or more embodiments, the board comprises between 12 and 16 panels.

[0029] According to one or more embodiments, the column comprises N adsorbent beds separated by n trays, the number of adsorbent beds N and the number of trays n being identical and between 4 and 24, and preferably between 8 and 19, very preferably between 12 and 15. According to one or more embodiments, the at least one third side has a height between 300 mm and 1200 mm, preferably between 500 mm and 800 mm.

[0030] According to one or more embodiments, the at least one third side has a thickness of between 10 mm and 100 mm, preferably between 20 mm and 50 mm.

[0031] According to one or more embodiments, the metal frame has a length L of between 0.5 m and 5 m.

[0032] According to one or more embodiments, the metal frame has a width I of between 0.4 m and 2 m, preferably between 0.8 and 1.4 m.

[0033] According to one or more embodiments, a first end of the at least one third side is supported by the ferrule and the second end of the at least one third side is supported by the main beam and / or the central mast, or the ferrule.

[0034] According to one or more embodiments, the frame comprises at least one stiffener disposed above the upper grid and connecting two third opposite sides of the metal frame.

[0035] According to one or more embodiments, the frame comprises from 1 to 3 stiffeners.

[0036] According to one or more embodiments, the height of the stiffeners is between 20 and 1200 mm and preferably between 500 and 800 mm.

[0037] According to one or more embodiments, the distribution and collection internals comprise in the direction of flow of the main fluid: a collector (or collection zone) adapted to collect the main fluid leaving the upstream adsorbent bed; a separation plate, separating the collector from a distributor and comprising at least one outlet opening for sending the main fluid from the collector to the distributor (or distribution zone); and the distributor adapted to distribute the main fluid on the downstream adsorbent bed, the panel further comprising an injection-withdrawal box adjacent to the separation plate and arranged at a substantially central position of the panel, the injection-withdrawal box being adapted to collect main fluid and / or to inject a secondary fluid and to mix the secondary fluid with the main fluid.

[0038] According to one or more embodiments, a panel is substantially triangular (3 sides) or trapezoidal (4 sides) in shape when viewed in the direction of flow of the main fluid. According to one or more embodiments, the third sides of the panels of a tray are parallel or concentric or radial.

[0039] According to one or more embodiments, the first side and / or the second side of a panel is at least partially in the shape of an arc of a circle.

[0040] According to one or more embodiments, the first side and the second side of a panel together form an arc of a circle.

[0041] According to a second aspect, the present invention can be defined as a simulated moving bed separation method, comprising the following steps: at least one column according to the first aspect is fed with at least one feed and one desorbent, and at least one extract and at least one raffinate are withdrawn from the column, the feed and withdrawal points in the trays of the column being offset over time by a value corresponding to an adsorbent bed with a permutation period and determining a plurality of operating zones of the column, and in particular the following main zones: by definition, each of the operating zones is designated by a number: zone I for desorption of a product to be separated (e.g. paraxylene) is between the injection of the desorbent and the withdrawal of the extract; zone II for desorption of impurities (e.g. isomers of the product to be separated) is between the withdrawal of the extract and the injection of the feed;Zone III for adsorption of the product to be separated is between the injection of the feedstock and the withdrawal of the raffinate; and Zone IV is between the withdrawal of the raffinate and the injection of the desorbent, a process in which the adsorbent beds are distributed in Zones I to IV according to configurations known as a / b / c / d type, i.e. the distribution of the beds is as follows: a is the number of beds in Zone I; b is the number of beds in Zone II; c is the number of beds in Zone III; and d is the number of beds in Zone IV, a process in which: a = (t * 0.2) * (1 ± 0.2); b = (t * 0.4) * (1 ± 0.2); c = (t * 0.27) * (1 ± 0.2); and d = (t * 0.13) * (1 ± 0.2), or a = (t * 0.17) * (1 ± 0.2); b = (t * 0.42) * (1 ± 0.2); c = (t * 0.25) * (1 ± 0.2); and d = (t * 0.17) * (1 ± 0.2), wherein t is a natural integer between 6 and 24, preferably between 8 and 19, most preferably between 12 and 15.;

[0042] According to one or more embodiments: the feedstock comprises a mixture of aromatics with 8 carbon atoms; and / or the desorbent is selected from the group consisting of one or more isomers of diethylbenzene and toluene, preferably the desorbent is paradiethylbenzene or toluene, very preferably, the desorbent is paradiethylbenzene; and / or the adsorbent used comprises or consists of a Faujasite selected from the group consisting of BaX, BaKX, and BaLSX.

[0043] According to one or more embodiments: the temperature in the adsorbent beds is between 140°C and 189°C, preferably between 155°C and 185°C, very preferably between 170°C and 180°C; and / or the pressure in the adsorbent beds is between 1 MPa and 10 MPa, preferably between 2 MPa and 4 MPa, very preferably between 2 MPa and 3 MPa; and / or the permutation period is between 30 seconds and 100 seconds, preferably between 40 seconds and 80 seconds; and / or the superficial velocity between the beds is between 0.2 cm / s and 2.5 cm / s and preferably between 0.5 cm / s and 2 cm / s.

[0044] Other characteristics and advantages of the invention according to the aforementioned aspects will appear on reading the description below and non-limiting examples of embodiments, with reference to the figures appended and described below.

[0045] List of figures

[0046] Figure 1 shows a vertical sectional view of a portion of a multi-stage column comprising adsorbent beds Ai separated by trays Pi.

[0047] Figure 2 shows a top view of the beams of a reference multi-story column, the beams comprising a main beam and 12 secondary beams.

[0048] Figure 3 shows a top view of a tray arranged on the beam of Figure 2, the tray comprising 16 meridian panels. Figure 4 shows a top view of a tray arranged on the beam of the shell of the multi-story column of Figure 2, the tray comprising 16 radial panels.

[0049] Figure 5 shows a 3D view of a reference meridian panel arranged on 2 secondary beams.

[0050] Figure 6 shows a vertical sectional view of a portion of a multi-stage column implementing a fluid flow passing through an adsorbent bed arranged between two reference meridian panels supported by secondary beams.

[0051] Figure 7 shows a top view of a beam of a multi-story column according to the present invention, the beam comprising only a main beam and no secondary beams.

[0052] Figure 8 shows a top view of a tray arranged on the beam of Figure 7, the tray comprising 16 meridian panels according to the present invention.

[0053] Figure 9 shows a top view of a plate arranged on a radial edge of the internal wall of the shell of a multi-stage column according to the present invention, the shell being devoid of a main and secondary beam.

[0054] Figure 10 shows a 3D view of a meridian panel according to the present invention.

[0055] Figure 11 shows a vertical sectional view of a portion of a multi-stage column implementing a fluid flow passing through an adsorbent bed disposed between two meridian panels according to the present invention.

[0056] Figure 12 shows a top view of examples of metal frames of meridian panels and an angular sector panel according to the present invention.

[0057] Detailed description of the invention

[0058] Embodiments of the devices and methods according to the foregoing aspects will now be described in detail. In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the devices and methods. However, it will be apparent to those skilled in the art that the devices and methods may be implemented without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0059] In this specification, the term "comprise" is synonymous with (means the same as) "include" and "contain", and is inclusive or open and does not exclude other elements not recited. It is understood that the term "comprise" includes the exclusive and closed term "consist". Furthermore, in this specification, the terms "essentially" or "substantially" correspond to an approximation of ± 10%, preferably ± 5%, very preferably ± 2%. For example, an element disposed substantially at a certain position of a panel, may be disposed in the panel with an approximation of ± 10%, preferably ± 5%, relative to the width or height of the panel.

[0060] According to the first aspect, the invention can be defined as a simulated moving bed separation column comprising a shell comprising a plurality of adsorbent beds separated by a plurality of trays, each tray comprising a plurality of panels, called self-supporting, each panel being adapted to collect a main fluid coming from an upstream adsorbent bed and to supply a downstream adsorbent bed with the main fluid. In the present description, the term "self-supporting" means that the mechanical strength of the panel is sufficient to do without secondary beams, i.e., to ensure a maximum deflection of 10 mm, regardless of the location of the panel.

[0061] An LMS separation unit comprises at least one separation column divided into N adsorbent beds separated by n trays (defining inter-bed zones), each tray being itself able to be divided into a plurality of panels. Preferably, the number of adsorbent beds N and the number of trays n are identical and are between 4 and 24, and preferably between 8 and 19, very preferably between 12 and 15.

[0062] The division of the board Pi into panels is known from the prior art. The two most common types of division are the division into meridian panels and the division into panels corresponding to angular sectors. The meridian panels correspond to divisions of the board Pi into elements parallel to each other and contiguous so as to ensure complete coverage of the horizontal section of the board. The meridian panels are oriented according to a diameter of said board, and preferably have substantially the same width. According to one or more embodiments, each board is divided into between 4 and 24 panels, preferably between 12 and 16 panels. Preferably the panels are meridian panels.

[0063] The device

[0064] In the present description, the simulated moving bed separation column according to the present invention comprises the same characteristics as the reference column described above with reference to Figures 1 to 6, apart from the differences described below.

[0065] With reference to Figure 7, the simulated moving bed separation column according to the present invention comprises a shell 1 in which the mechanical strength of the panels can be ensured by one or more rims 2 arranged radially (perpendicular to the direction of flow 12 of the main fluid) on the internal wall of the shell 1.

[0066] According to one or more embodiments, the rim 2 of the ferrule 1 is continuous, i.e., annular. According to one or more embodiments, the ferrule comprises a plurality of discontinuous rims.

[0067] With reference to Figure 7, according to one or more embodiments, the simulated moving bed separation column according to the present invention further comprises a main beam 3 connecting two radially opposite sides of the shell 1 (arranged perpendicular to the direction of flow 12 of the main fluid), and / or a central mast 5 (arranged parallel to the direction of flow 12 of the main fluid, e.g. vertical mast), for example in the form of a tube, the main beam 3 and / or the central mast 5 being adapted to support (directly) a plurality of panels 6, called self-supporting.

[0068] With reference to Figure 8, a panel 6 comprises a metal frame with 3 or 4 sides parallel to the direction of flow 12 of the main fluid. According to one or more embodiments, the sides of the metal frame are solid plates. According to the invention, a first side 13 of the metal frame is arranged on one or more edges 2 (eg an annular edge) of the shell 1, and a second side 14 of the metal frame is arranged on the main beam 3 and optionally on the central mast 5. According to one or more embodiments, the second side 14 of the metal frame is arranged (only) on the central mast 5, for example when the panels 6 are arranged around the central mast 5 according to a radial cut (arrangement of the panels similar to that of Figure 4).

[0069] With reference to Figure 9, the first side 13 of the metal frame is arranged on one or more edges 2 (eg an annular edge) of the shell 1 and the second side 14 of the metal frame is arranged on one or more edges 2 (eg the annular edge) of the shell 1. Advantageously, when the simulated moving bed separation column does not comprise a main beam or central mast, for example when the diameter of the shell is less than 5 m, the panels 6 can rest on both sides 13 and 14 on the shell 1.

[0070] With reference to Figure 10 and Figure 11, the metal frame 7 of the panel 6 serves to hold together the elements of the panel 6 (grids and internals), and comprises in particular: an upper grid 8 or any other equivalent device (e.g. perforated plate) for supporting the bed of solid particles and ensuring the passage of the main fluid; a lower grid 9 or any other equivalent device (e.g. perforated plate) for ensuring the passage of the main fluid, and distribution and collection internals 10 located between said grids. With reference to Figures 8 to 12, the first side 13 and the second side 14 of the metal frame 7 are connected to each other by means of at least one third side (15), and the at least one third side (15) has a height (H) and a thickness (E) adapted to ensure the mechanical strength of the panel, which allows the removal of the secondary beams without altering the circulation of the fluid inside the panels.

[0071] With reference to figure 10 and figure 11, according to one or more embodiments, the height H and the thickness E of the third side 15 of the metal frame 7 are chosen to ensure a deflection of less than 15 mm, preferably less than 10 mm, very preferably less than 7 mm.

[0072] According to one or more embodiments, the at least one third side 15 has a height H of between 300 mm and 1200 mm, preferably between 500 mm and 800 mm. According to one or more embodiments, the height H of the third side 15 of the metal frame 7 is substantially equal to the height of the upstream adsorbent bed (eg ±10%, preferably ±5%, very preferably ±2%).

[0073] According to one or more embodiments, the at least one third side 15 has a thickness E of between 10 mm and 100 mm, preferably between 20 mm and 50 mm.

[0074] According to one or more embodiments, the metal frame 7 (eg the at least one third side 15) has a maximum length L of between 0.5 m and 5 m.

[0075] According to one or more embodiments, the metal frame 7 has a maximum width I (perpendicular to the third side 15) of between 0.4 m and 2 m, preferably between 0.8 and 1.4 m.

[0076] With reference to Figure 10, according to one or more embodiments, the frame comprises one or more stiffeners 16 (metal elements) arranged above the upper grid 8 and being connected to at least one third side 15. Advantageously, the at least one stiffener 16 is adapted to be immersed in the adsorbent bed and makes it possible to avoid buckling of the at least one third side 15. According to one or more embodiments, the at least one stiffener 16 is connected to two opposite third sides 15 of the metal frame 7. According to one or more embodiments, the third sides 15 of the panels 6 of a tray are parallel or concentric or radial.

[0077] According to one or more embodiments, the at least one stiffener 16 forms an angle of between 60° and 90° with the at least one third side 15. According to one or more embodiments, the at least one stiffener 16 is substantially perpendicular to the at least one third side 15. According to one or more embodiments, the at least one stiffener 16 forms an angle of between 65° and 85°, and preferably between 75° and 80° with the at least one third side 15.

[0078] According to one or more embodiments, the at least one stiffener 16 has a height (parallel to the direction of flow 12 of the main fluid) of between 20 mm and 1200 mm and preferably between 500 and 800 mm. According to one or more embodiments, the at least one stiffener 16 has a height of at least 50% of the height H of the at least one third side 15. According to one or more embodiments, the frame comprises from 1 to 3 stiffeners 16.

[0079] With reference to Figure 12, the metal frame 7 (seen in the direction of flow 12 of the main fluid) may be substantially in the shape of a triangle A, an arc of a circle B or a trapezium C. According to one or more embodiments, the metal frame 7 comprises a recess, as shown by the arc of a circle B and the trapezium D, to allow the passage of the central mast 5.

[0080] It is understood that a metal frame can be of different shapes. For example, when the shell does not include a main beam 3 or a central mast 5 (see Figure 9), the metal frame 7 can be in the shape of a circular segment. A first example of a circular segment E represents a part of a disc cut from the rest of the disc by a chord (intersecting lines), in which the first side 13 and the second side 14 together form the arc of the circle, and the third side 15 forms the chord. A second example of a circular segment E represents a part of a disc cut from the rest of the disc by a chord (intersecting lines), in which the first side 13 and the second side 14 together form the arc of the circle, and the third side 15 forms the chord. 2The circular segment F represents a part of a disk cut from the rest of the disk by two chords parallel to each other, in which the first side 13 and the second side 14 each form an arc of a circle, and two third sides 15 form the chords. According to the present description, a circular segment constitutes the part of a disk between a secant line and an arc (circular segment E), or between two secant lines (circular segment F).

[0081] The distribution and collection internals 10 generally comprise in the direction of flow 12 of the main fluid, a collector or collection zone adapted to collect the main fluid leaving an upstream adsorbent bed; a separation plate, separating the collector from the distributor; and a distributor or distribution zone adapted to distribute the collected main fluid alone or in mixture with a secondary fluid on the downstream adsorbent bed, the upper grid, the collector, the separation plate, the distributor and the lower grid extending from the first side 13 to the second side 14.

[0082] The distribution and collection internals 10 further comprise an injection-withdrawal box adapted to extract the main fluid collected by the collector or inject a secondary fluid to mix said secondary fluid with the main fluid. The injection-withdrawal box is adjacent to the separation plate and is arranged at a central position of the panel, ie located substantially in the vertical central axis of the panel. The vertical central axis of the panel is a transverse axis of the panel, ie an axis parallel to the direction of flow 12 of the main fluid and orthogonal to the plane formed by the separation plate.

[0083] Advantageously, the upper grid and the separation plate together form the collector (collection area) suitable for directing the main fluid to the injection-withdrawal box.

[0084] Advantageously, the separation plate comprises two lateral parts located on either side of the injection-withdrawal box, i.e., the injection-withdrawal box separates the separation plate into two lateral parts.

[0085] Advantageously, the separation plate comprises at least one, and preferably at least two, outlet opening(s), preferably arranged near or adjacent to the injection-withdrawal box, and being adapted to send the main fluid from the collector to the distributor. Preferably, at least one outlet opening is arranged on either side of the injection-withdrawal box. Depending on the operating mode of the panel, the main fluid can thus be collected in the injection-withdrawal box or mixed with a secondary fluid leaving the injection-withdrawal box. The main fluid and the secondary fluid thus mixed are redistributed to the downstream adsorbent bed Ai by passing through the distributor.

[0086] Advantageously, the lower grid and the separation plate together form the distributor (distribution zone) to direct the primary fluid collected alone or in mixture with a secondary fluid to the downstream adsorbent bed.

[0087] The process

[0088] The invention may also be defined as an LMS process using an LMS separation unit according to the invention, in which the feedstock to be separated is any mixture of compounds, such as aromatics having 7 to 9 carbon atoms, a mixture of normal and iso paraffins, or a mixture of normal and iso olefins.

[0089] Thus, the invention also relates to an LMS separation method using at least one separation column 1 divided into N beds of adsorbent Ai separated by n trays Pi comprising a plurality of panels 3 according to the invention.

[0090] In the rest of the text, we speak of a step to designate an operation or a group of similar operations carried out on a given flow at a certain point in the process. The process is described in its different steps taken in the order of flow of the flows or products. The LMS separation process comprises the following steps: column 1 is fed with at least one feed and one desorbent, and at least one extract and at least one raffinate are withdrawn from column 1, said column 1 comprising one or more beds of an adsorbent solid Ai interconnected in a closed loop (i.e., the last bed of the last adsorber being adapted to send the flow circulating in the first bed of the first adsorber) and separated by Pi trays according to the invention, the feed and withdrawal points in the trays of the column being offset over time by a value corresponding to an adsorbent bed with a permutation period (noted ST) and determining a plurality of operating zones of the LMS device, and in particular the following main zones, designated by definition by a number: zone I of desorption of the product (of interest) to be separated is included between the injection of the desorbent and the withdrawal of the extract; zone II of desorption of impurities (egisomers of the product to be separated) is included between the extraction of the extract and the injection of the feedstock; zone III of adsorption of the product to be separated is included between the injection of the feedstock and the extraction of the raffinate; and zone IV is included between the extraction of the raffinate and the injection of the desorbent.

[0091] According to one or more embodiments, the adsorbent beds are distributed in zones I to IV according to configurations known as a / b / c / d type, that is to say that the distribution of the beds is as follows: a is the number of beds in zone I; b is the number of beds in zone II; c is the number of beds in zone III; and d is the number of beds in zone IV.

[0092] According to one or more embodiments: a = (t * 0.2) * (1 ± 0.2); b = (t * 0.4) * (1 ± 0.2); c = (t * 0.27) * (1 ± 0.2); and d = (t * 0.13) * (1 ± 0.2), and in which t is a natural integer between 6 and 24, preferably between 8 and 19 (eg between 12 and 15).

[0093] According to one or more embodiments: a = (t * 0.17) * (1 ± 0.2); b = (t * 0.42) * (1 ± 0.2); c = (t * 0.25) * (1 ± 0.2); and d = (t * 0.17) * (1 ± 0.2), and in which t is a natural integer between 6 and 24, preferably between 8 and 19, very preferably between 12 and 15 (eg 12 or 15).

[0094] According to one or more embodiments, the desorbent is selected from the group consisting of one or more isomers of diethylbenzene and toluene. According to one or more embodiments, the desorbent is paradiethylbenzene or toluene. According to one or more embodiments, the desorbent is paradiethylbenzene.

[0095] According to one or more embodiments, the adsorbent used comprises / consists of a Faujasite selected from the group consisting of BaX, BaKX, and BaLSX.

[0096] According to one or more embodiments, the filler is a mixture of essentially C8 aromatic compounds (e.g. xylenes and ethylbenzene). According to one or more embodiments, the mixture comprises at least 95%, preferably at least 97% (e.g. at least 99%) of essentially C8 aromatic compounds. According to one or more embodiments, the filler comprises at least 15% by weight of paraxylene and / or 30% by weight of metaxylene relative to the total weight of the filler.

[0097] An example of an industrially important LMS separation process concerns the separation of aromatic C8 cuts to produce paraxylene of commercial purity, typically at least 99.7% by weight, and a raffinate rich in ethylbenzene, orthoxylene and metaxylene.

[0098] The extract produced contains desorbent, paraxylene and possibly traces of isomers (paraxylene purity greater than 98%, preferably greater than 99.7%). This extract can be treated to separate the desorbent (e.g. by distillation) and can optionally be purified by crystallization to increase the purity of paraxylene.

[0099] According to one or more embodiments, the temperature in the adsorbent beds is between 140°C and 189°C and preferably between 155°C and 185°C, particularly preferably between 170°C and 180°C.

[0100] The pressure is adjusted so that the liquid phase remains at all points in the process according to the invention. According to one or more embodiments, the pressure in the adsorbent beds is between 1 MPa and 10 MPa, preferably between 2 MPa and 4 MPa, preferably between 2 MPa and 3 MPa. According to one or more embodiments, the ST permutation period (period between two successive permutations of the feeds / extractions) used is between 30 seconds and 100 seconds. Preferably, the ST permutation period used is between 40 seconds and 80 seconds (eg 60 ± 10 seconds).

[0101] According to one or more embodiments, the surface velocity between the beds is between 0.2 cm / s and 2.5 cm / s and preferably between 0.5 cm / s and 2 cm / s.

[0102] Examples

[0103] Example 1: Sizing

[0104] The deflection of a metal plate is inversely proportional to its quadratic moment l qz , which is for a plate of rectangular section of height (H) and thickness (E), as defined below in the mathematical formula Math 1.

[0105] Math 1

[0106] This moment shows that height has much more impact on vertical deformation than plate thickness.

[0107] Thus, we can compare a reference device and a device according to the invention in which the third side (15) of the metal frame (7) has been increased in height up to the bed height. Table 1 below offers this comparison by considering an identical deflection in both cases, therefore at iso-deformation. The results show that the device according to the invention makes it possible to reduce the mass of metal involved by 70%. The surface hidden from fluid circulation can serve as an indicator of hydrodynamics, and also shows a significant gain.

[0108] Table 1 Example 2: Hydrodynamics

[0109] The hydrodynamics of a reference device and a device according to the invention are evaluated through CFD simulation and the results are compared in terms of Peclet number. This is a dimensionless number illustrating the ratio of convection and axial dispersion. The higher this number is, the more plug flow and the more efficient the process is. The Peclet is calculated according to the following formula, where p is the first moment and o is the second centered moment. The moments are obtained by calculating the propagation of the moments in the bed, following the methodology described by Liu et al (see AlChE Journal, Vol 56, issue 10, pages 2561-2572), as defined below in the mathematical formula Math 2.

[0110] Math 2

[0111] / z 2

[0112] Pe = 2 x made with a third side 15 making the entire height of the bed.

[0113] Table 2

[0114] Example 3: Saving in assembly time

[0115] Current technology suffers from a long tray assembly / disassembly time, which penalizes the operating time of the entire aromatic complex. Stoppages for screen changes amount to months. The innovation presented eliminates the need to assemble the secondary beams. In addition, the step of stabilizing the panels on the beams is no longer necessary. This reduces the work inside the towers. The table below provides an estimate of the time savings per adsorbent bed, which is around 30%. Table 3

Claims

Claims 1. Simulated moving bed separation column comprising a shell (1) comprising a plurality of adsorbent beds separated by a plurality of trays, each tray comprising a plurality of panels (6), said to be self-supporting, each panel (6) being adapted to collect a main fluid coming from an upstream adsorbent bed (11) and to supply a downstream adsorbent bed (11) with the main fluid, each panel (6) comprising a multi-sided metal frame (7) in which are arranged: - an upper grid (8) adapted to support a bed of solid particles of the adsorbent bed (11); - liquid distribution and collection internals (10) arranged between the upper grid (8) and a lower grid (9); and - the lower grid (9), in which the metal frame (7) is supported on a first side (13) by the ferrule (1) and is supported on a second side (14) by: - a main beam (3) arranged diametrically in the shell (1); and / or - the ferrule (1) or a central mast (5) arranged in the ferrule (1), in which the metal frame (7) comprises at least one third side (15) connecting the first side (13) to the second side (14), and in which the at least one third side (15) has a height (H) and a thickness (E) adapted to ensure the mechanical resistance of the panel.

2. Column according to claim 1, in which the height (H) and the thickness (E) of the third side (15) of the metal frame (7) are chosen to ensure a deflection of less than 15 mm, preferably less than 10 mm, very preferably less than 7 mm.

3. Column according to claim 1 or claim 2, comprising N adsorbent beds separated by n trays, in which the number of adsorbent beds N and the number of trays n are identical and between 4 and 24, and preferably between 8 and 19, very preferably between 12 and 15, and / or in which each tray comprises between 12 and 16 panels (6).

4. Column according to any one of the preceding claims, in which the at least one third side (15) has a height (H) of between 300 mm and 1200 mm, preferably between 500 mm and 800 mm. Column according to any one of the preceding claims, wherein the at least one third side (15) has a thickness (E) of between 10 mm and 100 mm, preferably between 20 mm and 50 mm. Column according to any one of the preceding claims, wherein the metal frame (7) has a length L of between 0.5 m and 5 m, and or the metal frame (7) has a width I of between 0.4 m and 2 m, preferably between 0.8 and 1.4 m. Column according to any one of the preceding claims, wherein a first end of the at least one third side (15) is supported by the shell (1) and the second end of the at least one third side (15) is supported by the main beam (3) and / or the central mast (5), or the shell (1).Column according to any one of the preceding claims, wherein the frame comprises at least one stiffener (16) arranged above the upper grid (8) and connecting two third opposite sides (15) of the metal frame (7). Column according to claim 8, wherein the frame comprises from 1 to 3 stiffeners (16), and / or the height of the stiffener (16) is between 20 and 1200 mm and preferably between 500 and 800 mm. Column according to any one of the preceding claims, wherein the distribution and collection internals comprise in the direction of flow (12) of the main fluid:. - a collector adapted to collect the main fluid leaving the upstream adsorbent bed; - a separation plate, separating the manifold from a distributor and comprising at least one outlet opening for sending the main fluid from the manifold to the distributor; and - the distributor adapted to distribute the main fluid on the downstream adsorbent bed, the panel further comprising an injection-withdrawal box adjacent to the separation plate and arranged at a substantially central position of the panel, the injection-withdrawal box being adapted to collect main fluid and / or to inject a secondary fluid and to mix the secondary fluid with the main fluid. Column according to any one of the preceding claims, in which a panel (6) is substantially triangular or trapezoidal in shape seen in the direction of flow (12) of the main fluid.

12. Column according to any one of the preceding claims, in which the third sides (15) of the panels (6) of a tray are parallel or concentric or radial.

13. Column according to any one of the preceding claims, wherein the first side (13) and / or the second side (14) of a panel (6) is at least partially in the shape of an arc of a circle.

14. Column according to any one of the preceding claims, in which the first side (13) and the second side (14) of a panel (6) together form an arc of a circle.

15. A method of separation in a simulated moving bed, comprising the following steps: at least one column according to any one of the preceding claims is fed with at least one feed and one desorbent, and at least one extract and at least one raffinate are withdrawn from the column, the feed and withdrawal points in the trays of the column being offset over time by a value corresponding to an adsorbent bed with a permutation period and determining a plurality of operating zones of the column, and in particular the following main zones: by definition, each of the operating zones is designated by a number: - zone I of desorption of a product to be separated is between the injection of the desorbent and the withdrawal of the extract; - impurity desorption zone II is between the extraction of the extract and the injection of the charge; - zone III of adsorption of the product to be separated is between the injection of the feedstock and the withdrawal of the raffinate; and - zone IV is between the raffinate withdrawal and the desorbent injection; process in which the adsorbent beds are distributed in zones I to IV according to configurations known as type a / b / c / d, i.e. the distribution of the beds is as follows: - a is the number of beds in zone I; - b is the number of beds in zone II; - this is the number of beds in zone III; and - d is the number of beds in zone IV, process in which: - a = (t * 0.2) * (1 ± 0.2); - b = (t * 0.4) * (1 ± 0.2); - c = (t * 0.27) * (1 ± 0.2); And - d = (t * 0.13) * (1 ± 0.2), or - a = (t * 0.17) * (1 ± 0.2); - b = (t * 0.42) * (1 ± 0.2); - c = (t * 0.25) * (1 ± 0.2); And - d = (t * 0.17) * (1 ± 0.2), method in which t is a natural whole number between 6 and 24, preferably between 8 and 19, very preferably between 12 and 15.

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