MXPA98002866A - Process and container for the regeneration of a catalyst, including a control of the completion of the combust - Google Patents

Abstract

The present invention relates to a process for regenerating a catalyst in a fixed or mobile bed, for example a reforming catalyst or a production of aromatics, which includes an end-of-combustion control stage that is carried out after the The catalyst has undergone all the combustion stages of the process. The control stage is carried out by injecting a gas containing the oxygen in the zone where the control takes place, the control stage being carried out in the most severe conditions than the combustion stages. The control stage develops with an oxygen consumption of less than 10%. Advantageously, the temperature remains substantially constant. The enclosure for the implementation of the invention is also claimed

Description

PROCESS AND CONTAINER FOR THE REGENERATION OF A CATALYST, QÜE INCLUDES A CONTROL OF THE COMPLETION OF THE COMBUSTION FIELD OF THE INVENTION The invention relates to the regeneration processes of used catalysts, intended to restore their initial catalytic operations. It refers more particularly to the combustion stage. Particularly well applied to catalysts for the production of aromatics, and mainly to the reformation. It is very advantageous for regenerations with mobile catalyst beds.

BACKGROUND OF THE INVENTION The aromatics production or reforming catalysts generally comprise a support (for example formed of at least one rebellious or refractory oxide, the support can also include one or more zeolites), at least one noble metal (the platinum preferably) , at least one metal promoter (for example tin or rhenium), at least one halogen and REF: 27216 optionally one or several additional elements (such as alkaline, alkaline earth metal, lanthanide, silicon, elements of group IV B, non-noble metals, elements of group III A, etc.). Catalysts of this type contain, for example, platinum and at least one other metal deposited on a chlorinated alumina support. In a general manner, these catalysts are used for the conversion of naphthenic or paraffinic hydrocarbons capable of being transformed by dehydrocyclization and / or dehydrogenation; in reforming or for the production of aromatic hydrocarbons (for example production of benzene, toluene, ortho-, meta- or paraxylenes): These hydrocarbons come from the fractionation of crude oils by distillation or other transformation processes. These catalysts are widely described in the literature. Your regeneration is equally well known. It is developed in a fixed or mobile bed, with a combustion stage in one or several combustion zones, then an oxychlorination stage, followed by a calcination stage. EP-A-378 482 of the applicant describes a moving bed process.

To facilitate understanding, the method according to the invention will be described from the regeneration in a moving bed of reforming catalysts. It is thus convenient to refer to the prior art of EP-A-378 482 in particular. According to EP-A-378 482, the used catalyst is progressively advanced from top to bottom in a regeneration chamber where it is successively located a first zone of moving and radial combustion bed, a second zone of moving and radial combustion bed, a zone of axial moving bed of oxychlorination and a zone of moving axial bed of calcination, and: a) in the first combustion zone , the catalyst is treated under a pressure of 3 to 8 bar substantially equal to that prevailing in the first reforming reactor, at a temperature comprised between 350 and 450 ° C by a combustion gas based on an inert gas circulating radially. already countercurrent to the catalyst, which contains 0.01 to 1% oxygen by volume, this combustion gas that comes from a zone of washing of gases from calcination, oxychlorination and combustion n. b) in the second combustion zone, the catalyst is treated under a pressure of 3 to 8 bar substantially equal to that prevailing in the first reactor at a temperature higher than at least 20 ° C at the temperature prevailing in " The first combustion zone, in the presence of gases coming from the first combustion zone and in the presence of an additional inert gas to which is added up to 20% by volume of oxygen so that the catalyst is in contact with a gas that encloses 0.01 to 1% oxygen by volume, these gases circulate radially and countercurrent to the catalyst, the catalyst is then sent to the oxychlorination zone., during the operation of this regeneration process, it is important that the combustion be completed (complete) before going to oxychlorination (or at any other next stage). If it is not, it is necessary to modify the combustion conditions to obtain it. Accordingly, the applicant has developed a process for regenerating a catalyst, a process that includes a control zone for the termination or end of combustion, before any subsequent stage, and which has means to control the end of the process. combustion. The depositor knows a patent US-4 578 370 which has a temperature adjustment zone, after the combustion stage and before oxychlorination in a regeneration process of a reforming catalyst. In this process, the gas conducted in the combustion zone circulates radially in the catalyst bed, and the combustion oxygen essentially comes from the calcination zone located at the bottom of the regeneration zone, after the zone. of combustion. The function of the temperature adjustment zone is to modify the temperature of the catalyst leaving the combustion zone to bring it to a temperature close to that of the oxychlorination zone, in order to reduce the thermal shock suffered by the catalyst during its entry. in the oxychlorination zone. For this fact, a gas is injected in the temperature adjustment zone, this gas is a compressed part of the effluent released from combustion.

This gas is at the temperature of the compressed effluent released from combustion. It has not undergone any cooling or overheating since one of the objectives of this procedure is not to use heating means, and in general to reduce the equipment. The gas that enters the temperature adjustment zone is mixed at its exit from the bed, with the gas that comes from the oxychlorination and rises again mixing with the combustion fumes to the upper part of the regeneration chamber where it is removed. Through the temperature adjustment zone, the gas heats the catalyst.

DESCRIPTION OF THE INVENTION The present patent application proposes a method that includes an area located after the combustion has been effected, but this area allows solving a different problem (the control of the end of the combustion) by means not used in the patent US-4 578 370. More precisely, the present invention relates to a process for regenerating a used catalyst that includes a combustion of the carbon material, in at least one combustion stage in which the catalyst is contacted with at least one gas containing the oxygen, under the determined operating conditions, the process is characterized in that the catalyst which has undergone all the combustion stages is, in a control stage, put in contact with at least one so-called control gas containing oxygen in the the conditions more severe than those of the combustion stages, and that the control stage develops with an oxygen consumption lower than 10% of the oxygen that enters with the gas. The severity of the conditions in the control zone is obtained by introducing by the control gas an amount of oxygen at least equal to the largest amount of oxygen introduced in a combustion stage and / or introducing the control gas at a higher temperature. to that of the gases introduced in combustion. The first means is preferred. Advantageously, the control stage develops at a substantially constant temperature. By "substantially constant temperature" is meant a temperature that does not vary more than 3% and preferably not more than 2%, in the near measurement errors and in the near thermal wastes. Advantageously, the temperature of the control gas introduced is at least equal to the highest temperature of the gas (s) introduced in the combustion stage. Preferably, it is superior. Preferably, the temperature is of the order of magnitude of the temperature of the gases and / or of the catalyst leaving the last combustion zone. For this purpose, control is advantageously made, after passing over the catalyst, at the level of the control gas leaving the process independently of other gases emitted from the combustion stage. It can also be easily carried out on a control gas which leaves in mixture with at least one gas left from at least one combustion stage. The catalyst used is regenerated, for example, in a fixed bed or in a moving bed with direct or intermittent current. The invention is illustrated in the figures included here, which represent: Figure 1: a control zone included in the last combustion zone with a moving bed of catalyst.

Figure 2: a control zone after a combustion stage, with a moving bed of catalyst. - Figure 3: position of the front of the flame. Figure 4: Measurement of the position of the front of the fiama. Figure 1 only represents the combustion of the regeneration process, which takes place here in two stages in two different zones, according to, for example, the process described in EP-378 482. In a known manner, the catalyst C used to regenerate enters the top (2) of the regeneration enclosure E through the conduit (1). The catalyst is then introduced through one or several ducts (3) (for example jambs) into a first combustion zone Zl. In this zone, the catalyst undergoes a first burn or combustion with the help of a gas Gl containing the oxygen introduced by the conduit (4) passing through the walls (5a) and (5b), of the grids for example, between which the catalyst is contained. Generally, the combustion zones are radial, and preferably annular in the case of the moving bed shown in Figure 1.

In the case of the mobile catalyst bed, the current is continuous. Intermittent currents can also be seen. The catalyst C then descends through one or several ducts (6) (for example jambs) in the second combustion zone Z2, into which a gas G2 containing oxygen is introduced through a pipe or duct (7). The gas G '2 after the passage in this second combustion zone is extracted from the zone by the conduit (9). The catalyst C then descends through the ducts (10) (for example jambs) to the oxychlorination zone, not shown here. It is treated after combustion in a known manner to ensure its regeneration (oxychlorination, calcination). Two successive combustion zones have been represented on FIG. 1, the number of combustion zones is chosen by the person skilled in the art according to the installation to be conceived. They work and are arranged in the same way as the areas described above. Certain processes (such as those described in US Pat. No. 4 578 370) operate with a single combustion zone in which one or several gaseous flows containing the oxygen at one or more points enter. The invention applies to that which is the number of combustion zones, it suffices that it has one. For example, the gas circulating radiantly in the catalyst stream (as represented in the figures for example). According to FIG. 1, the regeneration process thus comprises two combustion stages, and, immediately before its exit from combustion and before entering the further treatment zones, the catalyst is subjected to a control stage. This operation is carried out in the lower part (in the direction of the catalyst current) of the last combustion zone Z2, in this lower part there is an area FC called control of the end of the combustion. In normal operation, there is no unrolling or combustion in this lower part, in other words, it is situated after the end of the combustion front (flame front). In a general manner, the control zone FC is located in the lower portion of the last combustion zone, and better in the lower third. It will be of interest to reduce the control area with respect to the combustion zone; thus a control zone located in the lower 20% of the combustion zone, or better 15% agree. This makes control beyond the end of the flame front that is up to when more 98%, up to 95% or at most 80% of the height of the combustion zone. Then, as illustrated in FIG. 1, the catalyst is subjected to at least one combustion stage that develops in at least one combustion zone, in which at least one gas containing the oxygen is introduced, and the catalyst it is subjected to a control stage of the end or completion of the combustion in a control zone that is located in the lower part of the last combustion zone, the control gas is introduced at the level of the control zone. The measurement of the temperature and / or the amount in oxygen are preferably carried out in the gas leaving the level of the zone, but the temperature prevailing in the mobile catalyst bed or the temperature of the catalyst can also be measured. In the embodiment shown in Figure 2, the control zone FC is a zone not included in the last combustion zone Z2, but separated from it. The separation between the zone FC and the combustion zone or the last combustion zone has the function of preventing the passage of gas between these zones but allowing the passage of the catalyst. The person skilled in the art will choose the adapted means, for example a plate (29) according to figure 2. The combustion zones can be separated (see figure 2) or not separated (figure 1). A G3 gas containing oxygen enters the FC zone through the conduit (11) according to FIG. 1 (and (27) according to FIG. 2), gas that is extracted after passing through the zone FC by a duct (9) according to figure 1 by which the evacuation of the gas G '2 having crossed the combustion zone Z2 or through the duct is also effected. (28) according to FIG. 2 independently of G'2 (gas G'3). Then, as illustrated in Figure 2, the catalyst is subjected to at least one combustion stage being unwound or developed in at least one combustion zone, into which at least one gas containing the oxygen is introduced, and the The catalyst is subjected to an end-of-combustion control stage in a control zone separate from the combustion zone or the last combustion zone so as to allow the catalyst to pass through and prevent the passage of the gas, the control gas that It is introduced into the control zone and is extracted from said control zone.

From then on, the measurement of the temperature and / or the quantity of oxygen is preferably carried out in the extracted gas. In order to carry out severely the operating conditions in the control area in relation to the combustion zones, one means is that the gas introduced by the control stage, at the level of the FC zone in FIGS. 1 and 2, present a quantity of oxygen at least equal to and preferably greater than the largest amount of oxygen introduced in a combustion stage. In other terms, reporting in figures 1 and 2, the amount. of oxygen that enters with gas G3 is equal to or greater than that which enters with gas Gl and with that for gas G2. If the yields are equal, the oxygen amount of G3 is greater than that of Gl and that of G2. Another means taken alone or combined in the preceding means is that the introduced gas also preferably has a temperature at least equal to the highest temperature of gases introduced in the combustion stage. It may preferably be substantially equal to the temperature obtained at the end of the last combustion stage. In Figure 2, the gas G3 generally enters a temperature close to that to which the effluent G '2 of the second combustion zone exits. And according to Figure 1, the gas G3 has a temperature generally close to that of G '2 of the effluent leaving the second combustion zone that includes the zone FC. The G3 gases are generally at a temperature close to that which reigns or predominates in the moving catalyst bed by removing the last combustion zone. In an advantageous embodiment for optimizing the gas management, the effluent leaving G '2 is subjected to a cooling, a treatment for removing impurities, to a purge, a compression and preferably to a drying placed before the compressor or after the compressor on all or part of the gas. The gas is divided into two parts, one that is recirculated in combustion and the other that is sent as gas G3 in the FC zone after any oxygen supply and eventual overheating. Thus, in general, the gas G3 comprises at least part of the gas left from the last stage of combustion, and preferably in its entirety, added with oxygen (it is understood that an oxygen-containing gas such as air can be conducted) .

The control zone FC is distinguished from a combustion zone in which the oxygen consumption is in the zone FC less than 10% of the oxygen entering, advantageously at the most 5% of the incoming oxygen. Generally, the temperature of the latter remains substantially constant. Which means that combustion is consummated. To measure the temperature (s) at the level of the control zone, a medium is arranged, for example, of one or two thermocouples or thermoelectric pairs at the level of the central collector (defined by the inner wall). (5a) in Figure 1) and at the level of the FC zone. The average temperature of the gas leaving the zone FC is thus known, which is compared with that of the gas entering the zone FC. If the gas has circulated in the opposite direction to that of Figure 1, ie from the interior (of the space delimited by the inner wall) to the outside, the thermocouples or thermocouples would be placed at the level of the external wall (5b). Another means is to measure the temperature that predominates in the catalytic bed or the temperature of the catalyst for example from a thermocouple submerged in the bed.

Any means of temperature measurement is convenient: thermocouple, infrared analyzer ... In the case of a moving catalyst bed moves in a single combustion zone, the same way is used to measure the temperature, arranging the Measurement means (s) at the level of the wall through which the gas from the FC zone exits. On the contrary, the measurement becomes easier and thus the control more reliable if the zones of combustion and of control are separated so that they allow to pass the catalyst but they prevent that the gases pass, since the gas leaves the FC zone independently of other gases. It is clearly noted that the patent US Pat. No. 4,578,370 of the prior art does not have the necessary means to define a control zone such as in the invention. Also, the person skilled in the art will choose the adapted means for measuring the oxygen consumption in the FC zone. For example, in a simple way, the variation of the oxygen quantity between the input and the output of the FC zone can be measured from a variation of the quantity in the input (to the same total gas yield) and the measurement of the variation of the amount that leaves the area. In general, if the operation of the preceding stages (zones) is correct, the oxygen consumption in the FC zone must be reduced (less than 2-3% for example). This means of measurement is particularly well suited when the FC zone is included in the last combustion zone and the last combustion zone is separated from the combustion zone preceding it so that the combustion gases issued from the last zone do not pass in the preceding combustion zone. The medium is also easily applicable in the case of the FC zone separated from FIG. 2. There are thus simple means to control the correct operation of the combustion, and it can be remedied in the combustion deficits by varying the temperature or the rate of oxygen in at least one combustion zone. In fact, in the process the temperatures of the gas and / or of the introduced catalyst and of the gas and / or of the catalyst leaving in the control stage and / or the quantities of oxygen of the introduced gas and of the gas leaving in the stage of control are measured, compared, and if there is a difference greater than the allowable variations, at least one operative condition of at least one combustion stage is modified so as to correct the difference.

(A method to operate this combustion control will be described a little further, from the knowledge of the advance of the combustion obtained by the reference point of the position of the front of the flame.). Preferably, the temperature or the amount of oxygen of the introduced and leaving gases will be compared. Another possible comparison is between the temperatures of the catalytic bed or the catalyst entering and leaving the control zone. If the difference in temperature does not exceed 3%, including 2% of the temperature of the incoming gas (outside determinable thermal wastes) or if the difference in quantity in oxygen is less than 10% of the amount of oxygen in the incoming gas ( if it is desired to do in a severe form the coercion of at most 5%), then the combustion reaction will be considered finished (because the difference is in the limit of admissible variations). In the opposite case (the difference greater than the admissible variations, it will be allowed to unroll or develop a combustion termination (afterwards with the operating conditions modified with respect to normal operation) to guarantee the suitable regeneration of the catalyst but at the same time, it will be modified at least one operating condition in at least one combustion zone so that the oxygen consumption in the control zone remains below 10% .The combustion dysfunction will be verified quickly and will be remedied in a very short period. It will be brief, at the moment, in the severe conditions of the zone, a termination of the combustion will take place For the treatment of reforming catalysts or aromatics production, the temperature conditions of the gas entering the control stage are of 400-550 ° C, and generally of at least 450 ° C, and preferably of at least 460 C, and 460 ° C often at 480 ° C until more. The amount of oxygen is at most 2%, preferably 0.5-1.5%, and preferably higher than the amount (s) of gases introduced in the combustion zone (s). The invention also applies to a fixed bed regeneration mode. Several beds or a single bed can be used, and the gas containing the oxygen can be introduced at several points in the bed or outside the bed. The fixed-bed catalyst is subjected to a gas containing the oxygen introduced through a duct, located for example at the bottom of the bed and exiting through another duct located, for example, at the head of the bed after its passage in the bed. The conditions that predominate in the reactor allow combustion to take place. It can take place in one stage or in several stages. For example, at a moment the temperature and / or the oxygen amount of the gas can be increased, and in this last stage, the combustion is pushed. When the last combustion stage is finished, a gas containing oxygen in equal quantity or preferably greater than the largest quantity of oxygen introduced in a preceding combustion stage (for example higher than that introduced in the second stage such as described above), and the gas that is introduced at a temperature at least equal to the highest temperature of the gases previously introduced, or advantageously substantially equal to the temperature of the gas leaving in the last stage of combustion. The temperature and / or the oxygen amount of the gas leaving is measured and compared to the temperatures and / or oxygen amount of the incoming gas.

In the same way as in the procedure in the moving bed, it will be determined if the oxygen consumption is within the admissible limits of the procedure. In the opposite case (difference greater than the admissible variations), a combustion termination will be allowed to develop (but with the operating conditions modified with respect to normal operation) to guarantee the convenient regeneration of the catalyst, or A new regeneration cycle will begin well with the modified conditions. At least one operative condition for the combustion of the next batch of the same catalyst will be modified accordingly to correct the difference. The person skilled in the art will adapt the temperature and oxygen quantity conditions of the gas entering the control zone as a function of the conditions prevailing in the combustion zones and within the specified limits of the invention. For regeneration procedures, which operate with a mobile bed of catalyst, and mainly for the process according to the invention, very advantageously combustion can be controlled and regulated by localization of the position of the flame front. A method to accomplish this is proposed below.

In this method for controlling the combustion of the carbonaceous material during the regeneration of a catalyst, the catalyst is circulated in a descending moving bed between at least 2 walls in a combustion zone, and is passed through a hot gas containing the oxygen that enters the bed by one of the walls and that comes out again by another wall, area in which develops a front of flame of inclined profile of which the highest point is at the level of the wall through which the gas enters and at the level of the entrance of the catalyst in the zone, and of which the lowest point is at the level of the wall through which the gas exits. The control of the combustion of the carbonaceous material, at the level of at least one of the areas where there is combustion, is, in this procedure, carried out in the following manner: at least one parameter XY of the area where it has combustion is measured. total and at least one parameter XN of the area where it has no combustion, is attributed to at least one reference point chosen in the vicinity or in the front of the flame, to obtain under normal operating conditions, a parametric function or parameter that includes XY and XN, the location of said point in the normal operating conditions constitute a reference consigned value, and the position is calculated, from measurement points located on the one hand and on the other hand of the consigned reference value, of a fictitious point calculated from the parametric function, then the position is compared to the reference consigned value, and, if there is a difference, at least one condition is modified. n operative so that reduces or eliminates the difference. The description of the invention will be continued from the figures. Figure 3 has been schematized in longitudinal section, a combustion zone with an annular bed delimited by 2 coaxial cylindrical walls, an external wall [31] and an internal wall [32]. A gas G containing the oxygen passing through the moving bed [33] of the catalyst, in a downstream stream according to FIG. 3, enters the zone at the level of the external wall (a grid according to FIG. 3). opening [34] (which constitutes the highest part of the combustion zone) and that leaves the combustion zone at the level of the opening [35]. The combustion zone thus has a height h (distance between openings [34] and [35], the inner wall [32] thus delimiting a central gas manifold [39].

The explanation of the invention is given here with a gas current or outlet from the outside to the inside, the inverse flow or flow is possible and the invention is equally applicable in this case. A flame front develops in the combustion zone, that is to say, an area where the combustion reaction is passed "rapidly". The flame front is referred [36] in figure 3. Its shape results from the fact that, at the top of the zone, the part of the bed located near the entrance wall of burned gases, and as the catalyst descends continuously , this part of the catalyst is a little lower and the oxygen present in this place will burn the coke located a little farther from the wall through which the gas enters. The flame front thus has a profile inclined downwards, the highest point of the front is at the level of the wall through which the gas enters (wall [31] according to figure 3) and at the level of the entrance of the catalyst (opening [34] according to figure 3), and the lowest point of the front is at the level of the wall through which the gas exits (wall [32] according to figure 3). The flame front thus separates the catalytic bed into 2 zones: forward of the flame front (zone [3.7]), the catalyst is transformed only into coke (or practically more) and is "cooled", when it reaches the front of the Flame (zone [38]) is transformed into coke and "heated". It has been found that, to be assured that practically all the coke is burned, the lowest point of the flame front (corresponding to the end of combustion) must be placed before the end of the combustion zone. In order to ensure real control of the position of the end of the flame front, a certain flexibility in its extreme position must be authorized, because the control is a variation around a setpoint, and it can be imposed that the lowest position, of setpoint, of the flame front will be advantageously placed when more than 98% of the height has to start from the heat of the combustion zone, preferably to more than 95% up to at most 85% when more 80%. In a general way, the end of the flame front is located in the lower third parts of the combustion zone. The operating conditions of the combustion zone are activated at the front of the flame, and thus at its lowest point. These are the speed of displacement of the catalyst then its performance or the mass or mass yield of coke to be burned, the amount of oxygen introduced (yield or rate of incoming gas, which contains oxygen x amount of oxygen), the temperature of this gas which are the most important parameters. The experiences and the conformation of the combustion reaction made by the applicant show that the rise in temperature and oxygen consumption are concomitant. The position indicators of the flame front are thus the temperature measurements or the oxygen consumption measurements (direct or by calculation). To know the temperature profiles, is to know the oxygen consumption. And knowing the consumption of oxygen, is knowing the progress of the combustion of coke. But the progress of combustion of coke is known by the temperatures and / or by the consumption of oxygen, which goes back to saying that knowledge of the flame front allows to know the state of combustion. Therefore, the location of the reference point (preferably under normal operating conditions, the lowest or lowest point of the flame front) will be detailed in terms of temperature profiles. (One could indifferently use the oxygen consumption profiles). But, taking into account the precision of the measurements of temperatures and concentration in oxygen made in the flows or gas regimes that enter and leave the combustion, it is illusory to search to locate precisely the end of the flame front from these unique information The localization method is explained later, starting from the lowest point of the flame front chosen as the reference point; It is valid for any other point of reference in front of the flame. The point of reference is close to the front of the flame or the front of the flame, in the area where there is a strong probability that it will develop under normal conditions. The operator determines, for normal operation, the operating conditions and thus the position PO of the lowest point of the flame front, and the zone of tolerated values in which PO can vary. When, during operation or at the beginning of the installation, these normal conditions are not met, the marking of the lowest point (or any other point) of the flame front reduces this dysfunction and corrects it by modifying the operating conditions. In the present case, the consigned reference value shall be named, the position of the lowest point of the flame front to be obtained under normal operating conditions. The same will be referred to as PO in figure 4. To indicate said position, PO (PI) and P1 ... PI, the Pi values are below from the setpoint position PO (towards the upper part of the combustion zone) and Pi decreasing or at the bottom of the PO (towards the lower part of the combustion zone). Figure 4 shows 5 measurement points (levels) P-2, P-1, PO, Pl and P2. It can be foreseen as much as necessary. Its separation is defined by the person skilled in the art according to the precision desired in the location of the lowest point of the flame front, of the desired speed of the correction to be provided; for this fact, it will be possible to help with simulation models and exploratory measurements. These measuring points are advantageously arranged, according to FIG. 4, at the level of the central collector [39] since they must be placed next to the wall through which the gas exits (if the gas flow or flow were inverse, the points measurement would be on the side of the external wall) because the point chosen here (below the flame front) is located at this level.

The person skilled in the art will choose the position of the best-adapted measuring points in his enclosure according to the chosen reference point (s). Figure 4 shows an arrangement in which the points Pl, PO and Pl are relatively close and arranged near the point PO corresponding to the value assigned to be respected, the point P2 is located here lower in the combustion zone and the point P-2 is located higher up in the combustion zone. For readability reasons, the points have been represented very far away without taking into account the real proportions; on the other hand the point P2 for easy reading is represented below the area, it could be higher. Thus, point P2 discloses the temperature TN (or T2) of combustion gas outlet when there is no combustion, because it is located farthest from the end of the flame front. The indicated temperature is to be compared with the temperature value measured at the inlet of the combustion bed and must be of the same order of magnitude otherwise this means that the position of the end of the flame front is quite low. An operating alarm can then be put into operation.

This point P2 is located, for example, in the lower third part of the combustion zone. The point P-2 informs about the exit temperature TY (or T-2) of combustion gases when they have combustion, because it is located in a zone of the bed where it always has reaction whatever the operating conditions (without However, it should not be placed closer to the start of the combustion bed to avoid edge effects). The location of this point in a combustion zone will allow to measure the plate temperature, which at the same time gives information about the burning conditions to which the catalyst is subjected (which depends mainly on the percentage of oxygen and the entrance temperature of the gases) but also allows indirectly but surely locate the flame front as detailed by what follows. This point P-2 is located, for example, in the upper third part of the combustion zone. The temperature of plate or portion is therefore the image of the oxygen consumed in case of total combustion; this is an information that can be used as a redundancy term with the input oxygen concentration information. Also, in case of reduced percentage of coke, this temperature is only the one that allows to confirm that the combustion normally develops in a weaker portion of the bed (in the case where the end of the flame front is between P-2 and Pl). ). The three points P-l, PO and Pl are used in order to give precise information about the location of the end of the flame front or any other point of the front of the flame chosen as a reference point. The location of these points corresponds to the area where the flame front normally ends, if the reference point is the lowest point of the flame front. It is thus provided, at these points of measurement, collectors (thermocouples for example) or any other means of temperature measurement (infrared analyzers for example). These means can be in whole or in part arranged outside the catalytic bed, in the advantageous case where the representative information can be obtained in the outgoing gas, the means are then in the vicinity of the wall through which the gas exits. . This is the case when the reference point is the lower or lower point of the flame front. These means may be partly located in the catalyst bed.

In addition to or instead of this temperature measurement, the oxygen quantity can be measured with oxygen analyzers, for example, in order to know, by difference with incoming oxygen, the consumption in oxygen. Figure 4 also shows the arrangement of the sensors at each measurement point, for example 3 sensors P-2, 1 and P-2, 2 and P-2, 3 are arranged at the point P-2 regularly on a section of the central collector. In this way, a plate temperature is measured or an average plate temperature is calculated. The temperature profile of the combustion bed (of the instrumented part) is obtained simply by making the temperature medium on each transverse plate in the following manner: tj = -? Vj, i * Tj, i? VJ.i With: - Tj, i represents the temperature of the collector n 'i of the plate j at the point Pj - Vj, i takes the value 0 if the collector Tj, i is out of service, or 1 if the collector is in service. - Tj is the average temperature of plate j. This formula simply indicates that the medium is only realized in the valid sensors. A sufficiently robust algorithm capable of detecting a flame front can be realized in the following way from previously calculated Tj measurements: - the level of the P-2 sensor allows to know the plate temperature in a place where a total combustion is present ( zone [38]), the level of the P2 sensor allows to know the temperature in a place where the combustion is absent (zone [37]), the flame front will be chosen arbitrarily as the place where the temperature is equal to a function of preceding temperatures f (TY, TN) for example, simply on the average of two preceding temperatures. In this simple case, a simple algorithm that allows finding this position performs the following operation: finding from below the combustion bed the first temperature above half of the temperatures T2 and T-2. Then interpolate between this temperature and the just preceding temperature the place where the temperature is equal to the average of the temperatures T2 and T-2. Then it is enough to add this value to the physical position of the collector of the first temperature found. Algorithmically: (initiation) (marking of two thermocouples that enclose the average temperature) for i = 2 to -2 if Ti > (T-2 + T2) / 2 PR = [(Ti- (T-2 + T2) 12) / (Ti-Ti + 1)] * (PTi-PTi-1) With (Ti: average value of the thermocouples of plate i PR: Position (in meter <O) with respect to PTi PTi: Position (in meter) of the sensor Pi that measures Ti in relation to the upper part of the combustion zone) (estimate of the position of the flame front by linear interpolation, from the top of the combustion zone) Ll - PTi + PR (in SI unit) Ll = (PTi + PR) / (length of the combustion zone) * 100 (in%) Other algorithms are considerable, for example the fictitious position of the end of the flame front can be evaluated from a linear combination of T-2, T-l, TO, TI, T2. In general, the fictitious position will be evaluated by a predetermined function of accessible temperature measurements Ti. The method according to the invention for controlling the basic combustion thus in the knowledge of a fictitious point defined for example as having a temperature equal to the average temperature in the total combustion zone and in the zone of absence of combustion. It is known that this fictitious point presents a good approximation of the actual or effective location of the lowest point of the flame front. The control procedure has been described above from the temperature parameter, another parameter can be oxygen consumption. The regulation by modification of at least one operative condition, and preferably of the quantity of oxygen entering the combustion zone, can then be effected if the fictitious point calculated above is outside the zone of values tolerated by the operator around from point PO. Examples of the regulation scenario: - the fictitious point is in PO: The flame front is in the desired position. The setpoint is maintained in the constant output or flow of 02. - the fictitious point is between P-1 and P-2: 02 is in excess. You can either bring back the end of the flame front to PO by reducing the amount of oxygen, or leave it as if the fictitious point is in P-l for example. According to the zones of values tolerated by the operator or entrepreneur, it will also be possible to authorize a front rise up to the P-2 level. - the fictitious point is between PO and Pl: There is not enough 02. The flow or regime of 02 should be increased. - When the flame front is quite high, the lower limit of the capacity of the control regenerator is reached. The event should be indicated by an alarm, and eventually pass to a degraded mode of combustion.

- When the flame front is very low, the upper limit of the capacity of the regenerator is reached. An alarm should be provided and the possibility of temporary burning in a following or continuous zone, n the oxychlorination zone for example. Then once this front located, the position of the fictitious point can be controlled by a classical PID type regulation (Proportional, integral, Derivative), or with the help of more marked algorithms of command type by internal model and / or not. linear that more accurately use the combustion model, or command predicted. A procedure operating with an annular bed, of which the two walls are cylindrical and coaxial, has been described above. It is also possible to work with a conical bed (the upper section of the bed is lower than that below the bed) or with a bed whose external wall is inclined, as described in US Pat. No. 4,859,643. , if the gas circulates from the internal wall towards the external wall (opposite to the direction described above), the measuring means are preferably arranged at the level of the external wall. When the installation and the procedure used in a catalyst regeneration comprises several combustion zones, the implementation of the control method described above is necessary in the last zone where the combustion takes place. It would thus be possible, for example, to control combustion in the second combustion zone by the regeneration process described in EP-A-0 378 482. However, this control can be completely applied to locate the end of the flame front in any area where combustion takes place and thus regulate combustion in this area. Very advantageously, this marking or reference point is made at the level of the last combustion zone of the process comprising a combustion control stage. The subject of the present invention is also an enclosure that implements the method described above. According to the invention, the enclosure for the regeneration of a used catalyst comprises at least one combustion zone provided with at least two walls (5a, 5b) between which the mobile bed catalyst circulates, and is provided with at least one conduit ( 4) for the introduction of at least one gas containing the oxygen entering the moving bed by one of the walls and coming out of another wall, it also comprises a control area (FC) of the end of combustion, located after at the end of the flame front of the last combustion zone (Z2) provided with a duct (11) for the introduction of a control gas containing the oxygen and at least one means for measuring the temperature and / or the quantity of oxygen in the gas and / or the catalyst issued or left the control zone. Advantageously, when the catalyst circulates in the annular space defined between two cylindrical walls, one or more measuring means are arranged at the level of the wall of the control zone through which the gas exits. In one embodiment, the control zone is located in the lower part of the last combustion zone. In another embodiment, the enclosure comprises at least one separating means (29) disposed between the control zone and the last combustion zone to prevent the passage of gases and allow the catalyst to pass through, and also comprises a conduit (28) for the exit of the gas issued from the control zone, and one or the measuring means are arranged in the outlet conduit (28).

One or the measuring means may also be arranged at the level of the wall of the control zone through which the gas exits. The enclosure according to the invention advantageously comprises a device for implementing the method of control by marking the position of the flame front. To implement the control procedure described above, a device is proposed for the control of the combustion of the carbonaceous material of a catalyst during its regeneration in a regeneration chamber comprising at least one combustion zone, the zone is provided with at least one opening for the entrance of the catalyst and at least one opening for its evacuation, the catalyst exits or flows in a moving bed in the combustion zone between at least 2 walls, one of the walls that allows the introduction into the bed of a hot gas containing oxygen driven by a opening of the regeneration enclosure, the gas that has passed through the bed exits through the other wall and is evacuated through an opening in the enclosure. The device comprises: - at least one means for measuring the temperature TY of the part of the area where there is combustion, at least one means for measuring the temperature TN of the part of the area where there is no combustion, at least 2 temperature measurement means Tj of the bed located at points Pj between the measuring means of TY and TN, and located on the one hand and on the other hand at the PO level in the combustion zone corresponding to the location of a reference point of the flame front to obtain under normal operating conditions and called reference reference value. - a means for calculating the position of a fictitious point corresponding to a point on the flame front, from temperature measurements Tj, TY, TN obtained at points Pj, and for comparing the position with the value of reference reference, - a means for regulating the operating conditions of the combustion zone linked to the preceding calculation means and means for modifying at least one operative condition. Preferably, the TN measuring means (s) is (are) located in the lower third part of the combustion zone. Advantageously, the measuring means (s) of TY are (are) located in the upper two thirds of the combustion zone.

It is interesting to provide that several temperature measuring means are arranged at the same measurement level, which thus lead to an average plate or slice temperature. Similarly, advantageously, when the 2 walls are cylindrical and coaxial, defining an annular bed of catalyst, the gas entering through the external wall and collecting in a collector defined by the internal wall, temperature measuring means are arranged in this collector. Also, advantageously, when the 2 walls are cylindrical and coaxial, which define an annular bed of catalyst, the. gas entering the combustion zone from the volume defined by the internal wall, which passes through the internal wall to cross the bed and which comes back out through the external wall, temperature measuring means are arranged at the level of the outer wall. It can also be considered that the temperature measuring means are distributed in the catalyst bed. A particularly advantageous device with detection of the lowest point of the flame front comprises: at least one means of measuring the temperature TY of the part of the area where there is combustion at the level of the wall through which the gas exits, - less a means of measuring the temperature TN of the part of the zone where there is no combustion at the level of the wall through which the gas exits, - at least 2 means of measuring temperatures Tj of the bed located at the points Pj between measuring means of TY and TN at the level of the wall through which the gas exits, and located on both sides of a PO level in the combustion zone corresponding to the lowest point of the flame front to be obtained under normal conditions of operation and called consigned reference value. - a means for calculating the position of a fictitious point corresponding to a point on the flame front, from temperature measurements Tj, TY, TN obtained at points Pj, and for comparing the position with the value consigned reference, - a means for regulating operating conditions of the combustion zone attached to the preceding calculation means and means for modifying at least one operative condition.

The means for modifying at least one operative condition are gateways for example. The temperatures Tj are those of the plate at the measurement level Pj.

In order to repair a temperature representative of what happens on a plate, several (for example three according to figure 4) sensors are regularly arranged in order to obtain at the same time: - a redundancy of necessary information because the test and the replacement of collectors can not be done in operation, an information in the profile of currents inside the regenerator (imbalance, plugging of jambs, preferential steps). In this case, several measurement means per plate and several measurement levels must be available. Thus in the longitudinal sense, there are "columns" of measuring means. In order to detect the presence of preferential steps, one can calculate in each of the three "columns" of thermocouples the top of deviations with respect to the average plate temperatures of these thermocouples, either: -POS /:? Vj, i * (Tj, i - Tj)? Vj With: POSI: represents the average difference in relation to the average of plate thermocouple measurements located in position i.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property

Claims (31)

1. A process for regenerating a used catalyst that includes a combustion of the carbon material, in at least one combustion stage in which the catalyst is brought into contact with at least one gas containing the oxygen, under the determined operating conditions, the process it is characterized in that the catalyst which has undergone any of the combustion stages is, in a control stage, put in contact with at least one so-called control gas under the most severe conditions than those of the combustion stages, and that the stage control is developed with an oxygen consumption less than 10% of the oxygen that enters with the gas.

2. The process according to one of the preceding claims, characterized in that the catalyst is a reforming catalyst or a catalyst for producing aromatics.

3. the method according to one of claims 1 or 2, characterized in that the temperature remains substantially constant during the control stage.

4. The method according to one of the preceding claims, characterized in that the control gas contains oxygen in an amount at least equal to the largest amount of oxygen introduced in a combustion stage and / or its temperature is higher than that of the introduced gases. in the combustion stages.

5. The process according to one of the preceding claims, characterized in that the temperatures of the gas and / or of the introduced catalyst and of the gas and / or of the catalyst leaving in the control stage and / or the amounts in oxygen of the introduced gas and / or of the gas leaving in the control stage are measured, compared, and if there is a difference greater than the admissible variations, at least one operating condition of at least one combustion stage is modified to correct the difference.

6. The process according to one of the preceding claims, characterized in that, after passing in the catalyst, the control gas leaves the process independently of other gases left from the combustion stage or in mixture with at least one gas left at least a stage of combustion.

7. The process according to one of the preceding claims, characterized in that the catalyst is in the form of a moving bed.

8. The method according to one of the preceding claims, characterized in that the catalyst is subjected to at least one combustion stage that develops in at least one combustion zone, in which at least one gas containing oxygen is introduced, and the catalyst is subjected to a control stage at the end of the combustion in a control zone separated from the combustion zone or the last combustion zone in such a way that it allows the catalyst to pass through and prevents the passage of gases, the gas from control that is introduced into the control zone and is extracted from the control area, the measurement of the temperature and / or the amount in oxygen is made in the extracted gas.

9. The method according to one of the preceding claims, characterized in that the catalyst is subjected to at least one combustion stage that develops in at least one combustion zone, into which at least one gas containing the oxygen is introduced, and that the catalyst is subjected to an end-of-combustion control stage in a control zone which is situated in the lower part of the last combustion zone, the control gas which is introduced at the level of the control zone and the Measurement of the temperature and / or quantity in oxygen are made in the gas at the zone level.

10. The process according to one of claims 1 to 5, characterized in that the catalyst is in the form of a fixed bed.

11. The regeneration process according to one of claims 1 to 9, characterized in that the catalyst flows in a descending moving bed between at least 2 walls in a combustion zone, and it is crossed by a hot gas that contains the oxygen that enters the bed through one of the walls and that comes out through the other wall, an area in which a flame front develops with an inclined profile of which the highest point is at the level of the wall through which the gas enters and at the level of the entrance of the catalyst in the zone, and from which the lowest point is at the level of the wall through which the gas exits, a procedure in which it is controlled the combustion of the carbonaceous material at the level of at least one of the areas where there is combustion in the following manner: at least one parameter XY of the zone where there is total combustion and at least one parameter XN of the area where there is no combustion is measured there is combustion, attributed to at least one reference point chosen in the vicinity or on the flame front, to obtain under normal operating conditions, a parametric or parameter function including XY and XN, the location of the point under the conditions normal of operation that constitutes a consigned reference value, and the position is calculated from measurement points located by both parts of the reference value, from a fictitious point calculated from the parametric function, then the position is compared with the value consigned reference, and if there is a difference, at least one operative condition is modified to reduce or eliminate the difference.

12. The method according to claim 11, characterized in that the lowest point of the flame front is located from the upper part of the combustion zone at a distance of at most 98% of total height of the combustion zone.

13. The method according to one of claims 11 or 12, characterized in that under normal operating conditions, the location of the lowest point of the combustion front constitutes the consigned reference value.

14. The method according to claim 11, characterized in that the moving bed has an annular shape.

15. The method according to one of claims 11 to 14, characterized in that combustion is controlled by modifying the amount of oxygen entering the combustion zone.

16. The method according to one of claims 11 to 15, characterized in that the combustion is controlled by modifying the flow rate or catalyst rate.

17. The process according to one of claims 11 to 16, characterized in that the catalyst passes through several combustion zones, and that the process is implemented in the last zone where combustion takes place.

18. The chamber for the regeneration of a used catalyst comprising at least one combustion zone provided with at least two walls between which the moving bed catalyst circulates, and provided with at least one conduit for the introduction of at least one gas containing the oxygen that enters the moving bed through one of the walls and exits through another wall, characterized in that it also comprises a control zone (FC) at the end of the combustion, located after the end of the flame front of the last combustion zone (Z2) provided with a conduit for the introduction of a control gas containing the oxygen and of at least one means for measuring the temperature and / or the quantity of oxygen in the gas and / or the catalyst left from the control area.

19. The enclosure according to claim 18, characterized in that the control zone is located in the lower part of the last combustion zone.

20. The enclosure according to one of claims 18 or 19, characterized in that the catalyst circulates in the annular space defined between two cylindrical walls, and that one or more measuring means are arranged at the level of the wall of the control area by the which is the gas

21. The enclosure according to claim 18, characterized in that it itself comprises at least one separation means arranged between the control zone and the last combustion zone to prevent the passage of gases and allow the catalyst to pass through, and that it comprises likewise a conduit for the outlet of the gas issued or taken out of the control zone, and that one or the measuring means are arranged in the outlet conduit.

22. The enclosure according to one of claims 18 or 19, characterized in that it comprises at least one separation means arranged between the control zone and the last combustion zone in a manner that prevents the passage of gases and allows the catalyst to pass through, and same also comprises a conduit for the exit of the gas issued from the control zone, and that one or the measuring means are arranged at the level of the wall of the control zone through which the gas exits.

23. The enclosure or container, according to one of claims 18 to 22, characterized in that it also comprises, at the level of at least one of the areas where there is combustion, a device comprising: - at least one means of measuring the temperature TY of the part of the zone where there is combustion, at least one means of measuring the temperature TN of the part of the zone where there is no combustion, at least two means of measuring temperatures Tj of the bed located at the points Pj between the measurement means of TY and TN, and located on both sides of a PO level in the combustion zone that corresponds to the location of a reference point of the flame front to obtain under normal operating conditions and called reference reference value, a means for the calculation of the position of a fictitious point that corresponds to a point of the flame front, from the temperature measurements Tj, TY, TN obtained at the points Pj, and for the comparison of the position with the consigned reference value, a means for the regulation of operating conditions of the combustion zone linked to the preceding calculation means and to the means for modifying at least one operative condition.

24. The enclosure according to claim 23, characterized in that the TN measuring means is located in the lower third part of the combustion zone.

25. The enclosure according to one of claims 23 or 24, characterized in that the measuring means of TY is located in the upper two thirds of the combustion zone.

26. The enclosure according to one of claims 23 to 25, characterized in that several temperature measuring means are arranged at the same measurement level, thus leading to an average plate temperature.

27. The enclosure according to one of claims 23 to 25, characterized in that the two walls are cylindrical and coaxial, which define an annular bed of catalyst, the gas that enters through the external wall and that is collected in a collector defined by the wall internal, the temperature measuring means are arranged in this collector.

28. The enclosure according to one of claims 23 to 27, characterized in that the two walls are cylindrical and coaxial, which define an annular catalyst bed, the gas entering the combustion zone from the volume defined by the internal wall, which passes through the inner wall to pass through the bed and which comes out through the external wall, the temperature measuring means are arranged at the level of the external wall.

29. The enclosure according to one of claims 23 to 28, characterized in that the temperature measuring means are distributed in the catalyst bed.

30. The enclosure according to one of claims 23 to 29, characterized in that the position of the fictitious point is controlled by a PID-type algorithm, command by the internal model, predicted command, or non-linear command.

31. The container enclosure according to one of claims 23 to 30, characterized in that it comprises: - at least one means for measuring the temperature TY of the part of the area where there is combustion at the wall level through which the gas exits, - at least one means for measuring the temperature TN of the part of the area where there is no combustion at the level of the wall through which the gas exits, - at least two means for measuring the temperatures Tj of the bed located in the points Pj between the measurement means of TY and TN at the wall level through which the gas exits, and located on both sides of a PO level in the combustion zone corresponding to the lowest point of the flame front to be obtained in Normal operating conditions and called reference setpoint value. - a means for calculating the position of a fictitious point corresponding to a point of the flame front, from measurements of the temperatures Tj, TY, TN obtained at the points Pj, and for the comparison of the position with the reference reference value. a means for the regularization of operating conditions of the combustion zone linked to the preceding calculation means and to the means for modifying at least one operative condition.