Device and method for high height / diameter ratio simulated moving bed separation - Patents.com

Abstract

The present invention relates to a simulated moving bed separation device and method comprising a plurality of series adsorbers (1, 2) interleaved in an upflow and downflow configuration, each adsorber (1, 2) being divided into n adsorption chambers, each containing an adsorbent bed, the n adsorbent beds being separated by n plates for injecting at least a feed and a desorbent and for withdrawing at least an extract and a raffinate.

Description

[Technical field]

[0001] The present invention relates to a device and method for simulated moving bed separation, in particular for the separation of para-xylene from a mixture of aromatic compounds containing eight carbon atoms (ortho-xylene, meta-xylene and ethylbenzene). [Background technology]

[0002] Current technology for separation by simulated moving bed (sometimes abbreviated as SMB in the remainder of the text) uses units with a certain number of common characteristics: - one or two adsorbents (or separation columns) each containing a plurality of adsorption chambers, the adsorption chambers being arranged between a distribution duct and a collection duct, the adsorption chambers containing an adsorbent bed through which the fluid flows; - an injection system, in particular for injecting the feed and the desorbent, and a withdrawal system, in particular for withdrawing the resulting effluents, called extract and raffinate, - Collection and redistribution system; called the interbed zone, for passing from one bed to the next.

[0003] A problem with current technology for SMB separations is that multi-unit adsorber units contain a large number of beds (typically 12 or more) with a low ratio of height H to diameter D (typically much less than 1), making them difficult to set up, use and maintain due to the lack of adsorber height.

[0004] Another problem with current technology for separation by SMB is that the fluid flow in the adsorbent bed is from top to bottom, and fluid from the bottom of the adsorber rises to the top of the adsorber or the next adsorber, which can result in thousands of m2 of adsorbent flow to heights of more than about 10 meters. 3 The problem is that it requires a large investment in energy and equipment (valves, pumps, etc.) to pump 100000 / h of fluid.

[0005] Another problem with current technology for separation by SMB is that the adsorber contains a large volume zone called the interbed zone, which limits the separation capacity and increases the need to use heavy equipment.

[0006] Another problem with current technology for separation by SMB is that it is necessary to shut down all beds (eg, 12 beds) of the adsorber to maintain or repair a given section of the adsorber. Summary of the Invention [Means for solving the problem]

[0007] (Summary of the invention) In the above context, a first object of the present specification is to overcome the problems of the prior art and to provide a device and method for separation by SMB that is easier to set up, use and maintain.

[0008] A second object of the present specification is to provide a device and method for separation by SMB that allows savings to be made in terms of energy and equipment.

[0009] A third object of the present specification is to provide a device and method for isolation by SMB that allows only a portion of the beds (e.g., one bed or a pair of beds) to be isolated without shutting down the remaining devices, which can be operated in a fallback mode and have satisfactory performance.

[0010] According to a first aspect of the present invention, the above objects as well as other advantages are obtained by a device for separation by simulated moving bed comprising a plurality of adsorber arranged in series, the adsorber arranged alternately for upflow and downflow, each adsorber divided into n adsorption chambers, each chamber containing one adsorbent bed, the n adsorbent beds being separated by n plates for injecting the feed and the desorbent and for withdrawing the extract and the raffinate.

[0011] According to one or more embodiments, the number m of adsorbers is between 3 and 15, preferably between 4 and 12, very preferably between 5 and 10.

[0012] According to one or more embodiments, the number m of adsorbers is an even number.

[0013] According to one or more embodiments, the number n of adsorbent beds per adsorber is 1-4, preferably 1-3, very preferably 1-2.

[0014] According to one or more embodiments, the total number of adsorbent beds t is between 6 and 24, preferably between 8 and 19, and very preferably between 12 and 15.

[0015] According to one or more embodiments, the adsorbent bed has a ratio H / D of height H to diameter D of 1 or more, preferably 1.5 or more, and highly preferably 2 or more.

[0016] According to one or more embodiments, the adsorbent bed has a ratio H / D of height H to diameter D of 1-12, preferably 1.5-10, very preferably 2-8.

[0017] According to one or more embodiments, the device further includes at least one bypass line adapted to bypass the at least one adsorber.

[0018] According to one or more embodiments, the bypass line is adapted to bypass two adjacent adsorber.

[0019] According to one or more embodiments, a bypass line connects the downflow adsorber to the upflow adsorber.

[0020] According to one or more embodiments, the adsorber is arranged in a vertical position to provide a substantially vertical distribution of fluid flowing through the adsorber.

[0021] According to one or more embodiments, the adsorber is arranged in a horizontal position so as to distribute the fluid flowing through it substantially horizontally. Advantageously, the flow (upstream / downstream) in the absorber may occur according to two opposite directions in a horizontal plane.

[0022] According to a second aspect of the present invention, the above mentioned objects, as well as other advantages, are obtained by a method for simulated moving bed separation using a device for simulated moving bed separation according to the first aspect, said method comprising the following steps: feeding at least one feed and a desorbent to an adsorber and withdrawing at least one extract and at least one raffinate from said adsorber, the adsorbent beds being interconnected in a closed loop, the points of feeding and withdrawal in the adsorber being shifted over time by switching times by an amount corresponding to one adsorbent bed, determining a number of operating zones of a device for separation by simulated moving bed, in particular the following main zones: - Zone I, for desorption of the product to be separated (for example, paraxylene), located between the injection of the desorbent D and the withdrawal of the extract E; - zone II, for desorption of the isomers of the product to be separated, located between the withdrawal of extract E and the injection of feed F; - zone III, for adsorption of the product to be separated, located between the injection of the feed F and the withdrawal of the raffinate R; and Zone IV, between the withdrawal of raffinate R and the injection of desorbent D.

[0023] According to one or more embodiments, the adsorbent beds are distributed in zones I-IV according to the following configurations, referred to as a / b / c / d type configurations: - 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; and - 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) Here, t is a natural integer of 6 to 24, and preferably 8 to 15.

[0024] According to one or more embodiments, the adsorbent beds are distributed in zones I-IV according to the following configurations, referred to as a / b / c / d type configurations: - 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; - d is the number of beds in zone IV, and - 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) Here, t is a natural integer of 6 to 24, and preferably 8 to 15.

[0025] According to one or more embodiments, the method includes at least one of the following operating conditions: - the desorbent is selected from the group consisting of one or more isomers of diethylbenzene and toluene; - the adsorbent used comprises / consists of a faujasite selected from the group consisting of BaX, BaKX and BaLSX; - the feed is selected from the group consisting essentially of a mixture of C8 aromatic compounds; - the temperature in the adsorbent bed is between 140°C and 189°C; - The pressure is controlled to maintain the liquid phase at all points in the device; - the switching time ST is between 20 seconds and 90 seconds; and - The average speed of the flow between the floors is 1000-5000 m / s 3 / h.

[0026] Other features and advantages of the present invention according to the aforementioned aspects will become apparent upon reading the following description and the non-limiting exemplary embodiments with reference to the accompanying drawings described below. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 shows in schematic form a reference device for separation by SMB, in which the adsorber is a downflow adsorber. [Diagram 2] FIG. 2 illustrates in schematic form a device for separation by SMB according to one or more embodiments of the present invention, in which the adsorber is an alternating downflow and upflow adsorber. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] (Description of the embodiment) The present invention relates to a device and method for simulated moving bed separations, in particular for the separation of para-xylene.

[0029] The embodiments of the device and method according to the aforementioned aspects will now be described in detail. In the following detailed description, many specific details are disclosed in order to provide a deeper understanding of the method. However, it will be apparent to those skilled in the art that the method can be performed without these specific details. In other cases, well-known features are not described in detail in order to avoid unnecessarily complicating the description.

[0030] In this patent application, the term "to comprise" is synonymous (has the same meaning) with "to include" and "to contain", is inclusive or open and does not exclude other elements not mentioned. The term "to comprise" is understood to include the exclusive and closed term "to consist". Furthermore, in this description, the terms "essentially" or "substantially" correspond to an approximation of ±5%, preferably ±1%, highly preferably ±0.5%. For example, an effluent that essentially comprises or consists of compound A corresponds to an effluent that contains at least 95% by weight of compound A.

[0031] The invention may be defined as a device or unit containing multiple adsorber (or separation columns) arranged in series for simulated moving bed separation of compounds (e.g., xylenes), each adsorber divided into n adsorption chambers, each containing one adsorbent bed, the n adsorbent beds being separated by n plates or interbed zones (i.e., n distribution zones and n collection zones), the adsorber arranged in alternating upflow and downflow. The distribution and collection zones include a collection and distribution system for passing the fluid flowing through the adsorber from one bed to the next.

[0032] In this patent application, the first distribution zone of the first adsorbent bed and the last collection zone of the last adsorbent bed are considered together to form a single interbed zone.

[0033] (device) The device for the separation by simulated moving bed according to the invention is, for example, a chromatography column or an adsorption column, operated as a simulated moving bed. Separation by simulated moving bed is well known in the art. In principle, a column operated as a simulated moving bed contains at least three zones, generally four, and sometimes five zones, each of which contains a certain number of successive adsorbent beds (for example fixed beds), each zone being defined by its position between the feed point and the withdrawal point. Typically, a simulated moving bed column is fed with at least one feed F (mixture of xylenes) to be fractionated and a desorbent D (sometimes called eluent), and at least one raffinate R (mixture of xylenes depleted in paraxylene) and an extract E (desorbent and paraxylene) are withdrawn from said column. The feed and withdrawal points are changed over time, typically shifted in the same direction by an amount corresponding to one adsorbent bed.

[0034] Advantageously, the upflow / downflow alternating arrangement of the adsorber of the device and method according to the invention allows to improve the assembly of the unit, to simplify and limit the equipment required, to improve the separation of the fluids, and to reduce the energy costs of operation by reducing the volume of the zones called interbed zones. Furthermore, the invention allows to maintain the unit, which may be completely isolated only one pair of beds, but without shutting down the rest of the unit, which can be operated in a fallback mode, with a sometimes reduced but still satisfactory performance.

[0035] The prior art describes in detail various devices that make it possible to achieve separation of feeds by means of a simulated moving bed, of which particular mention may be made of patents US 2,985,589, US 3,214,247, US 3,268,605, US 3,592,612, US 4,614,204, US 4,378,292, US 5,200,075 and US 5,316,821.

[0036] According to one or more embodiments, the distribution and collection zone includes systems for injection, in particular for the injection of a feed (e.g., a mixture of xylenes) and a desorbent (e.g., toluene or para-diethylbenzene), and systems for withdrawal, in particular for the withdrawal of product effluents called extract (e.g., a mixture of para-xylene and desorbent) and raffinate (e.g., a mixture of ortho-xylene, meta-xylene, desorbent and optionally ethylbenzene).

[0037] The controlled means / devices for feeding and withdrawing fluids from the device for separation by simulated moving bed are, for example, of one of two main types of technologies: - for each plate, a plurality of controlled on / off valves (possibly with flow regulating elements) for feeding or withdrawing fluids; these valves are typically located in close proximity to the corresponding plate. Each plate typically includes at least four two-way valves, controlled on an on / off basis to feed and desorbent, and withdraw extract and raffinate, respectively; or - A multi-way rotary valve for pumping or withdrawing fluid across all of the plates.

[0038] The present invention falls within the scope of particular relevance of columns operating in a simulated moving bed mode using a plurality of valves to feed and withdraw the various fluids.

[0039] Preferably, the number m of adsorbers is between 3 and 15, preferably between 4 and 12, very preferably between 5 and 10. Preferably, the number m of adsorbers is an even number.

[0040] Preferably, the number n of adsorbent beds per adsorber is 1-4, preferably 1-3, very preferably 1-2.

[0041] Preferably, the total number of adsorbent beds t is between 6 and 24, preferably between 8 and 19, very preferably between 12 and 15.

[0042] According to one or more embodiments of the invention, the adsorbent bed has a ratio H / D of height H to diameter D of at least 1 (preferably greater than 1), preferably at least 1.5, very preferably at least 2, such as at least 3 or 4. According to one or more embodiments of the invention, the adsorbent bed has a ratio H / D of height H to diameter D of at least 1 to 12, preferably at least 1.5 to 10, very preferably at least 2 to 8.

[0043] A further advantage of the device and method according to the invention lies in the possibility to use adsorbent beds having a ratio H / D of height H to diameter D larger than in the prior art, approaching the use of radial beds and allowing improved separations.

[0044] According to one or more embodiments, the device according to the invention further comprises a bypass line adapted to bypass at least one adsorber of the device, for example two adsorbers. Advantageously, it is possible to isolate only a portion of the adsorbent beds for maintenance, for example by isolating one or two consecutive adsorber and continuing the isolation method, with improved satisfactory performance compared to shutting down an adsorber with, for example, 12 beds.

[0045] According to one or more embodiments, a bypass line connects an upstream adsorber i (i=1-m) to a downstream adsorber i+2 or to a downstream adsorber i+3. According to one or more embodiments, the bypass line is adapted to bypass adsorber i+1 and / or adsorber i+2 by sending the flow leaving adsorber i to adsorber i+2 or adsorber i+3, for example by means of a bypass valve. According to one or more embodiments, the bypass line connects a downflow adsorber i to an upflow adsorber i+3.

[0046] According to one or more embodiments, the adsorber is arranged in a vertical array. The invention also applies to the case of a horizontal arrangement of the adsorber. The flows occur in two opposite directions in a horizontal plane. The concept remains the same as for upflow / downflow, and the associated advantages are the same.

[0047] Referring to Figure 1, a reference device for SMB separation includes a number of downflow adsorber (1), each of which includes a shell located between an upper and a lower dome. The downflow arrangement of the reference device corresponds to a generally downflow fluid flow in all adsorber, with a line connecting the bottom of adsorber i to the top of the next adsorber i+1. Typically, the reference device is a unit with 24 beds, including two downflow adsorber, each of which contains 12 beds.

[0048] Referring to FIG. 2, a device for SMB separation according to one or more embodiments of the present invention includes a plurality of adsorber arranged in an alternating upward and downward flow manner, each adsorber including a shell, the shell being positioned between an upper dome and a lower dome. The alternating arrangement of downflow adsorber (1) and upflow adsorber (2) of the device according to the invention corresponds to a generally upflow fluid flow in adsorber i, i+2, i+4 etc. and a generally downflow fluid flow in adsorber i+1, i+3, i+5 etc., with the top of adsorber i being connected to the top of the next adsorber i+1 and the bottom of adsorber i+1 being connected to the top of the next adsorber i+2. The device for separation by SMB according to one or more embodiments of the invention further comprises a plurality of bypass lines (3), each of which connects (in the direction of flow) an upstream downflow adsorber (1) to a downstream upflow adsorber (2), thus bypassing two adsorber.

[0049] (method) In the remainder of this specification, the term "step" is used to denote an operation or group of similar operations that is performed on a given stream at a given point in the process. The process is described in its various steps, which are carried out in a sequence of streams or product streams.

[0050] The method for separation by SMB comprises the following steps: feeding at least one feed F and a desorbent D to an adsorber, withdrawing at least one extract E and at least one raffinate R from said adsorber, interconnecting said adsorber containing one or several beds of adsorbent solids in a closed loop (i.e. the last bed of the last adsorber is adapted to send a flowing stream to the first bed of the first adsorber), shifting the feed and withdrawal points in the adsorber over time by a volume corresponding to one adsorbent bed, by a switching time (denoted ST), and determining several operating zones of the SMB device, in particular the following main zones: By definition, each of the operational zones is represented by a number: - Zone I, for the desorption of paraxylene, located between the injection of desorbent D and the withdrawal of extract E; - Zone II, for desorption of isomers, located between the withdrawal of Extract E and the injection of Feed F; - Zone III, for the adsorption of paraxylene, located between the injection of Feed F and the withdrawal of Raffinate R; and Zone IV, between the withdrawal of raffinate R and the injection of desorbent D.

[0051] According to one or more embodiments, the adsorbent beds are distributed in zones I-IV according to what is referred to as an a / b / c / d type configuration, i.e., the bed distribution 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.

[0052] 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) In the formula, t is a natural integer of 6 to 24, preferably 8 to 15 (eg, 12).

[0053] 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) In the formula, t is a natural integer of 6 to 24, preferably 8 to 15 (eg, 12).

[0054] In normal operation (e.g., without bypassing the adsorber), the feeding and withdrawal are performed with a predetermined percentage of the number of adsorbent beds operating in zones I-IV. For example, the percentage of adsorbent beds in zone I in normal operation is equal to a / t, where t is the total number of adsorbent beds. According to one or more embodiments, when a number x of adsorber are bypassed, the controlled device for feeding and withdrawal (e.g., a system with multiple all-or-nothing valves, multi-way rotary valves) is adapted to modify the location of the feeding and withdrawal points so that the predetermined percentage of the average number of adsorbent beds operating in zones I-IV is maintained within approximately ±20%, preferably ±10%, and highly preferably ±5%. For example, the percentage of adsorbent beds in zone I during bypass operation is equal to a / (tx).

[0055] In this description, a zone containing an "average number" of adsorbent beds corresponds to a zone that may contain exactly a first (natural) number X of adsorbent beds, and may contain exactly a second (natural) number X-1 or X+1 of adsorbent beds. For example, zone I containing 2.5 beds contains exactly 2 adsorbent beds, and zone I contains exactly 3 adsorbent beds.

[0056] According to one or more embodiments, during a first part of the replacement period ST (e.g., when the replacement of the feed and withdrawal points is asynchronous), at least one zone includes a first number X of adsorbent beds; during a second part of the replacement period ST, at least one zone includes a second number X+1 or X-1 of adsorbent beds.

[0057] According to one or more embodiments, during a first cycle time, or a first portion of the cycle time, at least one zone includes a first number, X, of adsorbent beds; during a second cycle time, or a second portion of the cycle time, at least one zone includes a second number, X+1 or X-1, of adsorbent beds. In this description, cycle time corresponds to the time during which the inlet and outlet points of the device evolve until they return to their initial positions.

[0058] According to one or more embodiments, when a number x of adsorber are bypassed, the feeding and withdrawal are performed during the bypass operation according to the following configurations a / b / c / d: - a=((tx)*0.2)*(1±0.2); - b=((tx)*0.4)*(1±0.2); - c=((tx)*0.27)*(1±0.2); and - d=((tx)*0.13)*(1±0.2) In the formula, t is a natural integer of 6 to 24, preferably 8 to 15 (eg, 12).

[0059] According to one or more embodiments, when a number x of adsorber are bypassed, the feeding and withdrawal are performed during the bypass operation according to the following configurations a / b / c / d: - a=((tx)*0.17)*(1±0.2); - b=((tx)*0.42)*(1±0.2); - c=((tx)*0.25)*(1±0.2); and - d=((tx)*0.17)*(1±0.2) In the formula, t is a natural integer of 6 to 24, preferably 8 to 15 (eg, 12).

[0060] Preferably, the number of bypassed adsorbers x is equal to 1 or 2, more preferably x is equal to 2.

[0061] For example, consider a reference simulated moving bed separation device, e.g. a tower containing 12 beds stacked in the same shell for the separation of a product, e.g. xylene. In case of bed failure (leak, breakage, etc.) on the 12-bed tower, the entire tower must be stopped, unloaded, reloaded, and then restarted. This requires a long period of time if the device is shut down, and there is no production.

[0062] Now consider a device according to the invention, which contains, for example, 12 adsorber units for the separation of a product, for example xylene, but in which a bed is defective. The bed can be isolated, preferably together with the adjacent beds, by means of a bypass line. The bypass is preferably made from the bottom of the adsorber, thus making it possible to open the insulated tops of the adsorber units, to unload them and to repair them. During maintenance operations, the simulated moving bed can continue to operate with the remaining 10 beds.

[0063] Advantageously, it is possible to adjust the arrangement to maintain the same distribution of adsorbent beds or sieves per zone. For example, for normal operation in the configuration 3 / 6 / 4 / 2. Maintenance can be performed during bypass operation in the 2.6 / 5.2 / 3.5 / 1.7 configuration. Advantageously, the method according to the invention may implement a synchronous movement of the inlet / outlet pipes, whereas in the device according to the invention an asynchronous movement of the inlet / outlet valves may be implemented, the asynchronous movement being also known as VARICOL. Advantageously, the production may be maintained at the desired purity. The yield of the operation may be somewhat affected by the lower volume of available sieves.

[0064] 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 para-diethylbenzene or toluene. According to one or more embodiments, the desorbent is toluene.

[0065] According to one or more embodiments, the adsorbent used comprises / consists of a faujasite selected from the group consisting of BaX, BaKX and BaLSX.

[0066] According to one or more embodiments, the feed is selected from the group consisting of a mixture of essentially C8 aromatics (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%) essentially C8 aromatics. According to one or more embodiments, the feed comprises at least 15% by weight para-xylene and / or 30% by weight meta-xylene, relative to the total weight of the feed.

[0067] One example of an SMB separation process of great industrial importance is the separation of a C8 aromatic fraction to produce para-xylene of commercial purity, typically a minimum of 99.7% by weight, and a raffinate enriched in ethylbenzene, ortho-xylene and meta-xylene.

[0068] The resulting extract contains the desorbent, para-xylene, and possibly trace isomers (>95% para-xylene purity, preferably >98%). This extract can be treated to separate the desorbent (e.g., by distillation) and then purified by either crystallization or simulated moving bed adsorption to increase the para-xylene purity.

[0069] According to one or more embodiments, the temperature in the adsorbent bed is between 140°C and 189°C, preferably between 155°C and 185°C, particularly preferably between 170°C and 180°C.

[0070] The pressure is adjusted so as to maintain the liquid phase at all points in the process according to the invention. According to one or more embodiments, the pressure in the adsorbent bed is between 1 MPa and 10 MPa, preferably between 2 MPa and 4 MPa, more preferably between 2 MPa and 3 MPa.

[0071] According to one or more embodiments, the switching time ST used (time between two successive switchings of pumping / extracting) is between 20 and 90 seconds. Preferably, the switching time ST used is between 30 and 70 seconds (for example 50±10 seconds).

[0072] According to one or more embodiments, the average velocity of the flow between the beds is 1000 m 3 / h~5000m 3 / h, preferably 2000m 3 / h or 2500m 3 / h~4000m 3 / h, highly preferably 3000m 3 / h~4000m 3 / h.

[0073] (Example) (Reference device) Consider a reference device for separation by SMB. This reference device consists of 12 adsorbers, each containing one adsorbent bed, with a volume of 45.9 m 3 and a ratio of height H to diameter D of H / D 4.

[0074] The flow is downflow in each adsorber.

[0075] The diameter of each adsorber is 3 m. The tangent-to-tangent height of the dome (4) is 12 m.

[0076] The average speed of the flow between the tokonoma is 3850m 3 / h.

[0077] The floor volume of the unit is 177.7 m 3 It is estimated that.

[0078] (Devices Conforming to the Invention) Consider a device for separation by SMB according to the invention, which consists of 12 adsorber units, each containing one adsorbent bed, the volume of the adsorbent bed being 45.9 m 3 and the ratio H / D of the height H to the diameter D is 4.

[0079] The flow is alternating upflow and downflow in successive adsorber.

[0080] The diameter of each adsorber is 3 m and the tangent-to-tangent height of the dome (4) is 12 m.

[0081] The average speed of the flow between the tokonoma is 3500m 3 / h.

[0082] The floor volume of the unit is 125.2 m 3 It is estimated that.

[0083] This example illustrates, among other things, the gain in interbed volume, which results in gains in flow velocity through the unit and therefore operational gains in operating costs as well as costs to build the unit (reduced mass of metal).

Claims

1. A device for separation by simulated moving bed, comprising a plurality of adsorbents (1, 2) arranged in series and arranged alternately for ascending and descending flow, each adsorbent (1, 2) being divided into n adsorption chambers, each chamber containing one adsorbent bed, the n adsorbent beds being separated by n plates for injecting a feed and a desorbent and for withdrawing an extract and a raffinate.

2. The device according to claim 1, wherein the number m of adsorbers is between 3 and 15.

3. 3. The device according to claim 1, wherein the number m of adsorbents is an even number.

4. A device according to any one of claims 1 to 3, wherein the number n of adsorbent beds per adsorber (1, 2) is between 1 and 4, preferably between 1 and 3, very preferably between 1 and 2.

5. A device according to any one of claims 1 to 4, wherein the total number t of adsorbent beds is between 6 and 24, preferably between 8 and 19, very preferably between 12 and 15.

6. A device according to any one of the preceding claims, wherein the adsorbent bed has a ratio H / D of height H to diameter D of 1 or more, preferably 1.5 or more, very preferably 2 or more.

7. A device according to any one of the preceding claims, wherein the adsorbent bed has a ratio H / D of height H to diameter D of 1-12, preferably 1.5-10, very preferably 2-8.

8. The device according to any one of the preceding claims, further comprising at least one bypass line (3) adapted to bypass at least one adsorber (1, 2).

9. 9. The device according to claim 8, wherein the bypass line (3) is adapted to bypass two adjacent adsorber (1, 2).

10. 10. A device according to claim 8 or 9, in which a bypass line (3) connects the downflow adsorber (1) to the upflow adsorber (2).

11. A device according to any one of the preceding claims, wherein the adsorber (1, 2) is arranged in a vertical position for a substantially vertical distribution of the fluid flowing through the adsorber (1, 2).

12. 11. A device according to any one of claims 1 to 10, wherein the adsorber (1, 2) is arranged in a horizontal position for a substantially horizontal distribution of the fluid flowing through the adsorber (1, 2), the flow through the adsorber (1, 2) occurring in two opposite directions in a horizontal plane.

13. A method for separation by simulated moving bed using a device for separation by simulated moving bed according to any one of claims 1 to 12, comprising the steps of: feeding at least one feed and a desorbent to the adsorber (1, 2) and withdrawing at least one extract and at least one raffinate from said adsorber (1, 2), the adsorbent beds being interconnected in a closed loop, the feed and withdrawal points in the adsorber (1, 2) being shifted over time by switching times corresponding to one adsorbent bed, defining several operating zones of the device for separation by simulated moving bed, including the following main zones: - zone I, for desorption of the product to be separated, located between the injection of the desorbent D and the withdrawal of the extract E; - zone II, for desorption of the isomers of the product to be separated, located between the withdrawal of extract E and the injection of feed F; - zone III, for adsorption of the product to be separated, between the injection of the feed F and the withdrawal of the raffinate R; and Zone IV, located between the withdrawal of raffinate R and the injection of desorbent D.

14. The method according to claim 13, wherein the adsorbent beds are distributed among the zones I to IV according to the following configurations, referred to as a / b / c / d type configurations: 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; and - 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) Here, t is a natural integer of 6 to 24, preferably 8 to 15.

15. The method according to claim 13, wherein the adsorbent beds are distributed among the zones I to IV according to the following configurations, referred to as a / b / c / d type configurations: 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, and - 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 Here, t is a natural integer of 6 to 24, preferably 8 to 15.

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