MXPA97004938A - Rinsing device in an adsorption unit in simulated mobile bed and its use - Google Patents

Abstract

The present invention relates to a rinsing device in a simulated mobile bed loading adsorption unit comprising a plurality of beds of an adsorbent, each of which is linked or connected by an organ or fluid distribution element that comprises a fluid distribution line to at least one charge input, at least one entry of a desorbent (or solvent), optionally at least one entry of an internal reflow, at least one transfer of an extract and at least one transfer of an refined, each entry and each transfer comprising an all or nothing valve or gate, the device is characterized in that each distribution line in each bed comprises at least one rinsing valve, the rinsing valve assembly is connected to at least one circulation line of a displaced fluid, said line comprises at least one pump for circulating the fluid and at least one means for controlling the flow or rate of f The valve is released by the pump, each one of the flushing valves is connected to an opening or closing command of said valves.

Description

RINSING DEVICE IN AN ADSORPTION UNIT IN SIMULATED MOBILE BED AND ITS USE FIELD OF THE INVENTION The invention relates to a rinsing device in a movable bed adsorption unit, countercurrent or co-current of a load. It particularly applies to the separation of aromatic hydrocarbons with 8 carbon atoms, mainly to obtain very high purity paraxylene.

BACKGROUND OF THE INVENTION The prior art is illustrated by the following patents: US-A-3 201 491, US-A-3 268 605, WO 96 12542 and WO 95 07740. In a process of separation by adsorption in simulated moving bed, it is mandatory to find: 1) a set of adsorbent beds (or fixed phase) placed in the form of closed loops, the total number of beds is generally between three and twenty-four.

REF: 24960 2) connecting means of each of these beds with the flows that feed the separation unit such as for example solvent (s), load (s) to be separated, internal reflux. 3) connecting means of each of these beds with the flows coming from the separation unit such as, for example, extract (s), refined product (s). 4) connecting means of each of the beds with the next bed (in the direction of fluid circulation). Following the particular type of embodiment, one can find either a device for recirculating fluid between the last and the first bed (pump or compressor), or a device that allows to ensure the interruption of flow between two successive beds (valve of all or nothing or gate) 0 a device that allows to regulate the flow and / or pressure at the entrance of each bed. Two types of realization are available: 1. Each bed is contained in an independent container and a line that connects it to the next. In this case, it is advantageous to connect a separate line with incoming and outgoing flow in this line. The AROMAX procedure of TORAY Industries will be included in this kind of realization, which constitutes an example of a large dimension. Although the individual beds are placed in a single column, they are separated by compact sheets, the set of fluid that comes from each bed is collected by a line which leaves the column and which enters, again, so that feeds the next bed. More generally, in units of smaller dimensions, it is convenient to isolate each bed in a particular container and link it or join it to the next bed by a line. In this type of embodiment, it is easy to use a line with incoming or outgoing flow and with a bed, which avoids any problem of contamination of one flow with another. Several beds are contained in a single container or column and each of the beds "is separated from the next by a distributor plate which must perform four functions: Collect the fluid collected at the end of the bed, take oe« xtraer during certain phases of the cycle a part of this fluid, such that the composition of the part taken or extracted is identical to the composition of the fluid assembly, - inject during certain phases of the cycle an external fluid in the internal fluid and perform a homogeneous mixture in the composition, - distribute the fluid at the entrance of the next bed. According to the PAREX procedure: a valve described in US Pat. No. 2,985,589 shows how it is possible to join or link at least two incoming flows and two outgoing flows sequentially to each of the beds containing the adsorbent. This patent clearly shows that each of the distributors is connected or connected by a single line to a valve which successively connects each distributor to the charge then to the extract, then to the solvent, then to the refined product. This procedure has the disadvantage of lowering considerably the qualities or results of the procedure (purity and yield) since each flow is thus contaminated by the content of the common line at the moment where a given flow is connected to a bed. particular.

For purely illustrative purposes, a column subdivided into twelve beds is considered and works as follows: In the period n ° 1 of the cycle (which comprises 12 periods), the solvent is injected into bed n ° 1, the extract it is extracted from bed n ° 3, the load injected in bed n ° 7 and the refined product is extracted from bed n ° 9. At the beginning of the second period of the cycle, the points of injection and of sample or extraction are displaced from a bed and the solvent injected in bed No. 2, the extract extracted or taken as sample from bed No. 4, is found, the load injected in bed n ° 8 and the refined product extracted or taken as sample from bed n ° 10. The cycle is continued until the second period in which the solvent is injected into the bed n ° 12, the extract is extracted from bed n ° 2, the load is injected into bed n ° 6 and the refined or refined product is extracted of the bed n ° 8. At the end of the first period, the line that connects or connects the distributor n ° 1 to the valve that ensures the management of the flows is then filled with solvent. At the beginning of the fourth period the refined product is extracted from bed No. 12, then by means of the line that has been used for solvent injection during period 1. During the time necessary for the evacuation of the volume of this line, it is extracted the solvent instead of extracting the refined or refined product. This results in a useless dilution that ultimately results in overconsumption of the solvent then in an operating surcharge. At the end of the fourth period, this line is full of refined product. During the seventh period, the load is injected into bed # 1. For a certain time, the refined product is rejected in bed No. 1 instead of injecting the load. It follows that the paraxylene in the charge suffers or undergoes a dilution by the refined product. As the productivity of the unit is proportional to the concentration of paraxylene in the load, the net or clear result is a decrease in productivity. At the end of the seventh period, the line is full of charge. During the tenth period, the extract is extracted from bed No. 12. During the time necessary in the exploration of the line, the load is transferred or emptied to the place of transfer of the extract. Resulting in a very important low purity, since the amount of paraxylene in the charge is of the order of 20% (but 80% impurities). This contamination makes it impossible to obtain high purity paraxylene. At the end of the tenth period, the line is filled with an extract. At the beginning of the first period, the solvent rejects the content of the line in the adsorber at the beginning of the paraxylene desorption zone (zone 1). A part of this paraxylene will thus remain adsorbed in the fixed phase, and is subsequently enlarged to mix in the flow of the refined product. Resulting in a loss of performance in paraxylene. In summary, contaminations due to the use of a common line connecting each of the four process flows at the entrance of the distributor plate cause an increase in solvent consumption, a decrease in productivity, a very sharp drop in purity and a drop in performance. Although it is known that in the procedure PAREX an injection intervenes between the transfer or pouring of the extract and the injection of load, the only document published on this subject refers to the injection of one or two internal reflows of extract or distilled refined product placed either between the extract and the load, or between the load and the refined product (US Patents 3 761 533). The fact of re-injecting the extract or the solvent between the charge and the extract solves only the problem of the strong low purity. In the ELUXYL process, instead of having to resort to a single valve that carries out the assembly or assembly of the connections between the different flows and each of the beds, there is a gate valve per flow and per bed. Although each of these valves is located closest to the bed that it loosens or releases, each distributor remains linked or connected to a solvent valve, an extract valve, a charge valve, a refined product valve and eventually an internal reflux valve. The object of the invention is to solve the drawbacks of the prior art.

DESCRIPTION OF THE INVENTION More precisely, the invention relates to a rinsing device in a one adsorption unit. load in a simulated moving bed comprising a plurality of beds (32) of an adsorbent, each of them is joined or linked by a fluid distribution member (34) comprising a line (35) for distributing the fluids in at least one loading inlet (38), at least one inlet (37) of a desorbent (or solvent), optionally at least one inlet of an internal reflow, at least one transfer (36) of an extract and at least one transfer (39) of a refined product, each inlet and each rake comprises a gate valve (36a, 37a, 38a, 39a), the device is characterized in that each distribution line (35) in each bed comprises at least one rinsing valve (41a), the set of rinsing valves is connected to at least one line (100) of circulating a displaced fluid, this line comprises at least one circulation pump (102) of the fluid and at least one control means (103 , 104) of performance or flow of fluid l With the pump released, each of the rinsing valves (41a) are connected to an opening or closing command member of said valves. The moving bed may be simulated countercurrent or simulated co-current. The desorbent can be a liquid phase or a supercritical, subcritical or gaseous phase. Under these conditions, by circulation pump, a compressor is also understood. The simulated moving bed process is described in the following patents: US 2985589, US 4498991, US 5422007, EP-B-531191 incorporated by reference. According to a first variant (Figure 1), the circulation pump can suck the fluid contained in at least one common branch of volume v of a given bed located between the fluid distribution member, the gate valves and the valve rinse, and it can compress it or discharge it to an outdoor collector. Conversely, the circulation pump can suck fluid from an outer collector and discharge it to a given adsorbent bed. According to a second variant of the rinsing device, the fluid circulation line can be a closed loop (figure 2), each of the rinsing valves is connected to said loop, the loop comprising at least one gate valve (201) sectioning or division defining at least two sections, two gate valves (112, 114 and 122, 124) to each of the ends of the loop adapted to join or link each end either in the suction or in the discharge or compression of the circulation pump, and of command means that allow to operate the section valve "3nto or division and the gate valves of each end of the loop, so as to orient the circulation of the fluid extracted in a section and that of the fluid discharged in another section of the loop in one direction or in the other. The closed loop of circulation may comprise n split or cut valves that define n + 1 sections. According to another embodiment of this second variant, an external fluid line can be connected to the suction of the pump or the compressor by a gate valve, so as to reject or discharge this external fluid towards a given bed. The discharge of the pump can be connected to an external line by another gate valve, so that I evacuated to an appropriate external collector the contents of one or several common branches. The invention also relates to the use of the rinsing device in a method of separating a load in at least one of its constituents, in a simulated moving bed for rinsing at the level of a bed, at least one common branch of volume v, located between the fluid distribution member, the gate valves (36a, 37a, 38a and 39a) and the rinsing valve (41a). This separation process can be applied to the separation of paraxylene from a charge of aromatic hydrocarbons of 8 carbon atoms comprising xylenes, in view of the preparation of acid or terephthalic anhydride, an intermediate in the synthesis of nylon, or methyl terephthalate, an intermediate in the synthesis of certain plastic materials. It can also be applied to the separation of diethylbenzenes as well as to the separation of ethylbenzene, of normal and isoparaffins, of olefins, sugars, and more generally to the separations of mixtures of products that depend on adsorption or on chromatography, for example. , the separation of optical isomers.

It can be applied in the separation of para-diethylbenzene from a mixture of diethylbenzenes, which is a good desorbent. According to a first mode of implementation of the method of use corresponding to the first variant of the device (Figure 1), the fluid contained in the common branch can be extracted sequentially during at least a part of a permutation period T [ located between the organ or fluid distribution element, the gate valves (36a, 37a, 38a, 39a) and the rinsing valve (41a)], at a flow rate -, v is the volume of the common branch, t < T, and it is discharged to the outer collector. By sequential extraction is meant an extraction synchronized with the other feeding and transfer operations during a part of at least one period of permutation (time elapsed between the moments in which the permutation from one bed to another is carried out). According to a second mode of implementation of the method of use corresponding to the first variant of the device (FIG. 1), a fluid of an external collector can be extracted sequentially during at least a part of a permutation period T. it is discharged into the common branch [located between the fluid distribution member, the gate valves (36a, 37a, 38a, 39a) and the rinsing valve (307)], at a rate or flow -, v is the Branch volume and t < T. According to a third mode of implementation of the method of use corresponding to the first variant of the device (figure 1), the fluid contained in the common branch can be extracted sequentially during a part of a period T of permutation [ located between the organ or fluid distribution element, the gate valves (36a, 37a, 38a, 39a) and the rinsing valve (41a)], corresponding to a bed of a given area and discharged h.acia the external collector and during another part of the period, said fluid is extracted from the external collector and discharged into the common branch of a bed located in another zone. It may be particularly advantageous to discharge the load of the common branch of a bed of zone 2 by the extract coming from an external line at a flow rate - with t < T during a part of the period of permutation T and the extract of the common branch of a bed of zone 1 is aspirated to discharge it during another part of the period in the extract transfer line. According to a first mode of implementation of the method of use corresponding to the second variant of the device (Figure 2), it is possible to extract during a part or fraction of at least one period T of permutation, the fluid contained in the common branch of a bed of a section and it is discharged into a bed of another section, at a flow rate - with t < T, the sectioning or division valve (201) between the two sections is closed. According to a second mode of implementation of the method of use corresponding to the second variant of the device (FIG. 2), during a part of at least one period T of permutation, the fluid contained in the common branch of a bed of a section and it is discharged in a bed of another section, to a yield or flow - with t < T, at least one of the sectioning or division valves (201, 202, 203) is closed. According to a third mode of implementation of the method of use corresponding to the second variant of the device (figure 2), the fluid of the common branch of a bed of a first section can be extracted sequentially during a part of a period and It is discharged into a bed of a different section and during another part of the period, the fluid is extracted from the common branch of a bed of another section and discharged into the bed of a different section. According to a fourth mode of implementation of the procedure of use corresponding to the second variant of the device (figure 2), the fluid of the common branch of a bed of one section can be extracted sequentially during a part of a period and it is discharged in a bed of another section and during another part of the period, the fluid is extracted from an external source and discharge in the same bed of said section or in a different bed. According to a fifth mode of implementation of the method of use corresponding to the second variant of the device (figure 2), the fluid of the common branch of a bed of a section can be extracted sequentially during a part of the period and discharge in a bed of another section and during another part of the period, the fluid contained in the common branch of a bed is extracted and discharged to an external source. In general, the volume of the common branch defined above is extracted or discharged 0.5 to 3 times. The invention will be better understood in view of the figures schematically illustrating an embodiment of the device and the method according to the invention, among which: * Figure 1 represents a set of implementation means to perform the rinsing device according to the invention. * Figure 2 shows the rinsing device with a rinsing fluid circulation line, in the form of a closed loop. * Figure 3 illustrates a connection of the rinse line to the level of each bed of the adsorption zone. * Figures 4a, 4b, 4c, 5a, 5b, 5c, 6a, 6b, 6c, 6d show a representation of different rinsing operations during a part of at least one period of time in relation to the different incoming flows (solvent (S), filler (F) and projections (refined (R) and extract (E)) According to figure 3, an adsorber 30, located in one or several columns, containing an appropriate adsorbent comprises seventeen beds 32. Each bed is connected by a distributor 34 to a line 35 which alternatively recovers the charge 37 and solvent 38 supplies controlled by valves 37a and 38a. Line 35 is on the other hand connected to the transfer lines of an extract 36 and a refined product 39 controlled respectively by the valves 36a and 39a. The line 35 is on the other hand connected or connected to a circulation line 100 of a rinsing fluid that collects all the lines 35 coming from the set of adsorbent beds 32. Each line 3 5 is controlled by a flushing valve 41a located between the feed or transfer lines and the line '100. The rinsing means 42 in the line 35 fed by the line 100 allow directing a fluid jet at the level of each feeding and transfer. Another valve 40 provided with a block is located on the line 35 between the feed or transfer lines and the distributor plate 34 and makes it possible to isolate the particular bed. All of these valves 41a are connected to an opening or closing command element or member 50, which can also command the operation of the valve assembly of the rinsing device. With the simplification procedure, (figure 1) the flushing valves 41a (numbered 1 to 17) correspond to the 17 beds of the adsorber. The line 100 of circulation is connected or connected by a line 110 via a valve 112 at the inlet of a circulation pump 102 and the discharge of the pump is connected to a line 119 in which a sectioning or division valve 113 is disposed. , and to a line 101 attached or connected to a fluid reservoir 130. The performance or flow rate of the pump is controlled by a regulating valve 103 and a flow meter 104. A sectioning or division valve 111 connects or connects the line 101 and the reservoir or container 130 at the inlet of the pump 102, while that another sectioning or division valve 114 on line 121 connects or connects line 119 to line 100 for circulating the rinsing fluid. With this device, it is thus possible to circulate the rinsing fluid of each bed towards the reservoir 130 by closing the valves 111 and 114 and opening the valves 112 and 113 or circulating the fluid of the reservoir 130 towards one of the beds of the reservoir. adsorber closing valves 113 and 112 and opening valves 111 and 114. When the fluid is not removed from any of the beds and when it is not injected, valves 111, 112, 113, 114 are closed and valve 11 i >; open so that the pump 102 is allowed to supply in a closed loop. According to a first mode of implementation of the device corresponding to the first variant, when it is desired to aspirate the content of the common line to the four flows, this operation must be carried out in a synchronized manner with the other operations carried out in the one or more Adsorption columns during the period between two permutations. For example, if you want to aspirate the plugging of cargo contained in the "common branch" during the period that exactly precedes extraction of extract, proceed as follows: in period n ° 1 of the cycle, it is admitted that the extract it is extracted from the bed n ° 4 (valve n ° 5 that puts in communication the exit of bed n ° 4 and the entrance of bed n ° 5). The rinsing valve n ° 6 is opened, valve n ° 112 is opened, which connect or connect the line 100 to the suction of the pump 102, a performance or flow equal to - for example (where v represents the volume) is imposed of the common branch and T the period of permutation) thanks to the regulating valve 103 and to the flow meter 104, the valve 113 is opened so that the fluid contained in the common branch is discharged towards the suction of the loading pump through the line 101. In this way, the charge plugging initially contained in branch No. 6 is discharged to the charging circuit, while the common branch is filled with liquid extracted in zone 2, which can be qualified as an extract Impure concentrate It should be noted that here the load contained in the common branch has been extracted with a yield or flow rate - v T * during a time T. The same operation can be performed very well ,, J. at one time - and with a yield or flow rate 2v T During another part of the period, pump 102 will continue to circulate the fluid in a closed loop, valves 111, 112, 113, 114 are closed and valve 115 open . During period n ° 2 the extract is extracted at the outlet of bed n ° 5 (valve n ° 6). The common branch that has been prepared during the preceding period is thus already full of extract. During period n ° 2, the common branch n ° 7 is prepared by means of the rinsing valve n ° 7, and so on from period to period. According to a second mode of implementation of the first variant, when it is desired to unload the jam or plugging occupied by the common branch in the adsorbers, this operation will also be carried out in synchronization with the other injections and racking. For example, if you want to unload the stuck or stuck extract in the adsorber during the period that exactly follows the extraction of the extract, proceed as follows: At least once, it is admitted that in period 1 of the cycle the extract it is extracted from the bed n ° 4 (valve n ° 5 that communicates the exit of bed n ° 4). Line 101 is connected or connected to the solvent circuit, valve 111 connecting line 101 to pump 102 is opened, valves 112 and 113 are closed. It is imposed for a time t. such as t1 < T a rate or flow rate - for example (in fc1 where v represents the volume of the common branch) thanks to the regulation valve 103 and the flowmeter 104, valve 114 is opened so that the solvent is discharged in line 100, open the rinse valve n ° 4 so that the extract contained in the common branch is expelled by the solvent. During period 4, when the solvent will be injected at the entrance of bed n ° 4, the common branch will be at the exit full of solvent. During period n ° 2 the common branch n ° 5 is prepared by means of the rinsing valve n ° 5 and so on from period to period. By means of this device, it is possible to remedy all the aforementioned drawbacks during a single and the same period, using the device of the invention in divided time, for example between each of the four flows. For example from t = 0 to Tj, it will be sucked with a regime or flow equal to - the load clogging or plugging located in the common branch of the bed from which the extract will be transferred during T T the following period. From t = i - a -, they will be sucked with a flow equal to - the clogging or plugging of refined product located in the common branch of the bed in which it will be injected. charge during the. T 3T next period. From t = - to -, the flow of solvent at the common branch of the bed from which the refined product is going to be transferred during the next 3T period will be aspirated at a rate or flow rate. From t = - - to T, the plugging of extract located in the common branch of the bed in which the solvent is going to be injected during the following period will be sucked with a flow rate equal to 4-v.

In the middle of the period, load clogging, refining of refined or refined product, plugging of extract and solvent packing, each with a flow - will be aspirated. The drawback is that it is not possible to practically perform a segregation of these different plugging of each of the four flows, and that the assembly must be returned to a column to distill via line 101 so that they separate from the solvent and of the load. Preferably, it is possible, on the other hand, to successively use this same device once in injection and once in transfer connecting or connecting the line 101 to a single and same flow so that two of the four aforementioned drawbacks are remedied or solved. Thus, for example from t = 0 to T- according to figure 4a, they will be rejected by means of the extract that comes from the transfer of extract injected with a flow equal to -, the charge plugging T located in the common branch of the bed in which the load has been injected during the preceding period.

T From t = - to T according to figure 4b, the plugging of extract located in the common branch of the bed in which the solvent will be injected during the following period and this one with a regime or flow of - to discharge it, will be vacuumed. towards the transfer T of extract. In this way, the yield or average flow of the extract will be constant: during the first half of the period, the yield or flow of the extract sent to the column to distill the extract will be E ~ "^ r when during the second half of the period, this flow rate will be E + T¡T • It is also possible to safeguard the flows in the four zones with respect to a system that does not need to rinse the line In figure 4c, it appears that to maintain in zones 1 to 4 the yields or flows D1, D2, D3 and D4, you must increase the flow rate of solvent and reduce the load flow of a value -, in relation to a system which will not include the common branch, so as to safeguard or protect the performance and In fact, the loss of productivity due to the reinjection of refined product in zone 3 and the waste of solvent due to the extraction of solvent with the refined or refined product have not been compensated. The four drawbacks mentioned above, it is necessary to use simultaneously two devices described according to figure 1. Figure 2 represents a preferred embodiment of the rinse device of a mobile bed adsorber simulated according to the invention. This adsorber comprises the lines and valves of figures 1 and 3 with the same functions. It also comprises twenty-four beds, for example, a rinse valve 41a per bed, numbered from 1 to 24 and a connecting device, according to figure 3, of each distributor between two consecutive beds with the line 100 for circulating the fluid in a closed loop. On this closed loop, the sectioning or division valves, three for example 201, 202 and 203 determine four sections each comprising six rinse valves 41a. The device represented by figure 2 allows to suck a fluid from any of the four sections and discharge it towards one of the other three. It is thus possible to displace the blockages or clogs initially contained in two common branches different from one another. For this, the suction of the pump 102 and the line 110 can be connected or connected to each of the two ends of the line 100: valve 112 (on the side of the 12th valve) and valve 122 (on the side of the 24th valve) ). Similarly, the discharge of the pump 102 and the line 119 may be connected or connected to each of the two ends of the line 100: valve 124 (12th valve side) and valve 114 (24th valve side) . It becomes equally possible to directly carry out the scheme shown in FIG. 4c. This presents, among others, the advantage of not being obligated or compromised in certain periods of the cycle, of changing the recirculation flow during the period in order to conserve or retain the constant flow rates in all the other zones. In order to facilitate the understanding, the operation of the preferred device according to the invention will be described, to perform the displacement represented in figure 4c. In period 1 of the cycle, it is indicated that the solvent is injected into bed n ° 1 and the load in bed n ° 13, while the extract and refined or refined product are extracted respectively from beds 6 and 18. During this period, the rinsing valve No. 2, the sectioning or division valves 202 and 203, and the valve 122 are opened so that the plugging of the extract located in the common branch of the bed 2 can be sucked by means of the pump 102 controlling the entire flow by means of regulating valve 103 and of flowmeter 104 and valve 124 and flushing valve n ° 12 are opened so that the charge plug located in the common branch of the container is rejected with the extract. bed n ° 12. By last, valves 201, 111, 112, 113 and 114 are closed. It is also possible to use the device successively for two different displacements during the cycle. Thus, three of the four aforementioned drawbacks can be remedied or solved by constantly keeping in the loop the compatible fluids between them, such as solvent and diluted extract, for example. When a very high purity is intended, it is preferred to rinse the common branch for several times its volume if one wants to be sure of completely eliminating the impurities. The overconsumption of solvent can be minimized by adopting, for example, the cycles of displacement described in figures 5 and 6. According to figure 5a: from t = 0 to 1.4 T (always with reference to period n ° 1 of the cycle) the rinsing valve No. 20 and the valve 122 are opened. The valves 201, 202 and 203 are closed. The pump 102 and the flow control loop allow discharging at a flow rate 2v / t to line 100 (valve 124 open, valve 112 closed) and valve rinsing no. 12 open. The solvent contained in the common branch coming out of the bed No. 19f is thus extracted and this solvent is replaced by the diluted refined product. This is why care is taken not to displace more than 0.8 times the volume of the common branch in order to avoid any contamination. The content of the line 100 rejects or pushes as far as it towards the absorber the majority of the charge plugging contained in the common branch of the bed n ° 12. According to FIG. 5b: from t = 0.4 T to 0.6 T, the rinsing valve of the bed No. 2 is opened, the valve 201 is closed, the valves 202 and 203 open as well as the valve 122. The pump 102, the control valve 103 and the flowmeter 104 make it possible to return the content with the flow 2-v.

It is thus finished moving the plugging of cargo that was in the common branch of the bed n ° 12 towards the interior of the absorber. In this way, it is avoided to return, during the end of the period (figure 5c), such a small volume of load that it is an immediate proximity of the extract extraction point. According to FIG. 5c: from t = 0.6 T to T, the rinsing valve of the bed No. 2, the isolation or division valves 202 and 203 and the valve 122 are opened. The valve 201 is closed. The pump 102, the control valve 103 and the flowmeter 104 make it possible to return the content of the line 100 to the rinsing valve of the bed n ° 8, passing through the valve 124. With the flow rate, a packing of the extract is thus sucked up. diluted, which is replaced by the solvent in the common branch of bed n ° 2, while the content of line 100 finishes rinsing the common branch of bed n ° 8. The content of line 100 is thus found to be a mixture of solvent and diluted extract. According to figure 6a: from t = 0 to 0.4 T, always with reference to period n ° 1 of the cycle, the rinsing valve of bed n ° 20 and valve 122 is opened. Pump 102 and the control loop flow rates allow discharge with a flow - to line 100 (valve 124 open and valve 112 closed). Valve 201 and rinse valve n ° 3 are opened. The solvent contained in the common branch that leaves the bed No. 19 is thus extracted, this solvent is replaced by the refined or diluted refined product. Care is thus taken not to displace more than 0.8 times the volume of the common branch, in order to avoid any contamination. The content of line 100 rejects, as for him on the adsorber, the majority of the plugging of extract contained in the common branch of bed No. 3. According to FIG. 6b, from t = 0.4 T to T, the rinsing valve No. 3 is left open. The valves 202 and 203 are opened. The pump 102, the regulating valve 103 and the flowmeter 104 allow discharge through the valve 112 to the line 100 with a flow rate of -. The solvent contained T in line 100 rejects the charge plugging contained in the common branch of bed n ° 12. The advantages of this way of operating are that the line 100 essentially contains the solvent and that each rinsing valve does not open and closes more than three times per cycle instead of four in the continuation of operations described in the case of the Figures 5a, 5b, 5c. It is also mentioned that the continuation of operations carried out in figures 6a and 6b is not equivalent to that of figure 6c since the plugging of the extract comprised between the injection of solvent and extract extraction is recovered, nor equivalent to that of the Figure 6d since in this case as in that of Figures 5a, 5b, 5c the content of line 100 would be a mixture of solvent-extract instead of being essentially solvent.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which refers to the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property

Claims (18)

1_. A rinsing device in a simulated movable bed load adsorption unit comprising a plurality of beds of an adsorbent, each of which is linked or connected by a fluid distribution member or organ comprising a distribution line of fluids to at least one charge input, at least one entry of a desorbent (or solvent), optionally at least one entry of an internal reflux, at least one transfer of an extract and at least one transfer of one refining, each entry and each racking comprises an all or nothing valve or gate, the device is characterized in that each distribution line in each bed comprises at least one rinsing valve, the rinsing valve assembly is connected to at least one circulation line of a displaced fluid, said line comprises at least one fluid circulation pump and at least one means for controlling the flow rate or rate of fluid released by the pump, each of the rinsing valves is connected to an opening or closing control member of said valves.

2. The device according to claim 1, characterized in that the circulation pump is adapted to suck the fluid contained in the common branch located between the fluid distribution member, the gate valves and the rinsing valve and relative to one of a given bed and to discharge said fluid to an external collector.

3. The device according to claim 1, characterized in that the circulation pump is adapted to suck the fluid from an external collector and to discharge it on a determined adsorbent bed.

4. The device according to claim 1, characterized in that the circulation line is a closed loop, each of the rinsing valves is connected to said loop, the loop comprises at least one sectioning or division gate valve which defines at least two sections, two gate valves in each of the ends of the loop adapted to join each end either to the suction or to the discharge of the circulation pump, and means of command that allow to operate the sectioning or division valve and the valves of gate of each end of the loop in such a way as to direct the circulation of the fluid withdrawn in one section and of the fluid discharged in another section of the loop in one direction or in the other.

5. The device according to claim 4, characterized in that the closed loop of circulation comprises n sectioning or division valves that define n + 1 -sections.

6. The device according to claim 4 or 5, characterized in that an external fluid line is connected either to the suction of the pump by a valve or to the discharge of the pump by a valve.

7. The use of the device according to one of claims 1 to 3, in a method of separating a load in at least one of its constituents, in simulated moving bed, for rinsing, in each period at the level of a given bed the branch common volume v located between the organ or fluid distribution element, the gate valves and the rinsing valve.

8. The use according to claim 7, in which the fluid contained in the common branch at a flow rate r, v is the volume of the common branch, is extracted sequentially during at least a part of a permutation period T, t < T, and it is discharged to the outer collector.

9. The use according to claim 7, in which a fluid from an external collector is withdrawn sequentially during at least a part of a permutation period T and discharged to the common branch at a flow rate p, v is the branch volume and t < T.

10. The use according to claim 7, in which the fluid contained in the common branch corresponding to a bed of a given area is withdrawn sequentially, during a part of a period T of permutation, and is discharged to the external collector and during another part of the period, said fluid is extracted from the external collector and discharged into the common branch of a bed located in another zone.

11. The use according to claim 7, in which the load of the common branch of a bed of zone 2 is discharged or compressed by the extract coming from an external line at a flow rate - with t * T during a part of the period of permutation T and the extract of the common branch of a bed of zone 1 is sucked to discharge it during another part of the period in said external line of transfer of extract.

12. The use of the device according to one of claims 1, 2, 4 to 6 in a method of separating a load in at least one of its constituents, in simulated moving bed, for rinsing in each period at the level of a given bed the common branch of volume v, located between the organ or fluid distribution element, the gate valves and the rinsing valve.

13. The use according to claim 12, in which, during a fraction or part of at least one permutation period T, the fluid contained in the common branch of a bed of a section is extracted and discharged into a bed of another section, at a flow rate - with t < T, at least one of the sectioning or division valves is closed.

14. The use according to claim 12, in which it is sequentially extracted during a part of a fluid period from the common branch of a bed of one section and discharged to a bed of another section and during another part of the period, is it extracts the fluid from the common branch of a bed of one section and is discharged into the bed of another section.

15. The use according to claim 12, in which the fluid of the common branch is extracted sequentially during a part of a period. of a bed of a section and it is discharged into a bed of another section and during another part of the period, the fluid is extracted from an external source and discharged into the same bed of said section or in a different bed.

16. The use according to claim 12, in which the fluid of the common branch of a bed of one section is extracted sequentially during a part of the period and is discharged into a bed of another section and during another part of the period, is it extracts the fluid contained in the common branch of a bed and is discharged to an external source.

17. The use according to one of claims 7 to 16, in which the volume of the common branch is extracted or discharged 0.5 to 3 times.

18. The use according to one of claims 7 to 17, wherein the filler contains a mixture of xylenes. SUMMARY OF AI 3-NVENCION A rinsing device and its use are described in a movable bed adsorption unit simulated with a load comprising a plurality of beds (32) of an adsorbent, each of which is linked or connected by an organ (34) fluid distribution comprising a line (35) of fluid distribution in at least one charge inlet (38), at least one inlet (37) of a desorbent (or solvent), at least one transfer (36) of an extract and at least one racking (39) of a refining, each entry and each racking comprises a gate valve (36a, 37a, 38a, 39a), the device is characterized in that each distribution line (35) in each bed comprising at least one rinsing valve (41a), the rinsing valve assembly is connected to a line (100) for circulating a displaced fluid, the line comprises a circulation pump (102) of the fluid and a regulator (103, 104) of the flow of fluid released by the pump, each of the rinsing valves (41a) is connected to an actuator or actuator (50) for opening or closing these valves. The application in the separation of aromatic hydrocarbons of 8 carbon atoms, mainly to obtain paraxylene of very high purity. Figure 3 to publish.