WO2025056356A1 - Assembly for collecting a gaseous fluid - Google Patents

Abstract

The present invention relates to an assembly for collecting a gaseous fluid, suitable for being arranged in a reaction section comprising a catalyst bed of a radial reactor (1'), and comprising a tubular grate (9), an external collection tube (10); and - an internal collection tube (11), the internal tube being arranged in the external tube, which itself is arranged in the tubular grate, wherein the tubes and the grate are arranged along the same axis, each of the internal and external tubes comprising openings, wherein the space between the external and internal tubes (10, 11) forms a first collection zone (Z2), and the space in the internal tube (11) forms a second collection zone (Z1), wherein each of the collection zones (Z1, Z2) is closed at one of its ends and opens at the other of its ends into a gaseous effluent outlet means provided with a removable closure means.

Description

GASEOUS FLUID COLLECTION ASSEMBLY

Technical field

The present invention relates to a gaseous fluid collection assembly for moving catalytic bed reactors having radial circulation of the feedstock, which involves flow through a catalytic bed in a set of directions corresponding to rays oriented from the periphery towards the centre. The present invention also relates to a radial bed reactor comprising a gaseous reaction effluent collection assembly. Finally, the invention relates, for example, to a method for catalytic conversion of a hydrocarbon feedstock using a radial bed reactor.

Prior art

The reaction unit (comprising one or more reactors in series) most representative of this type of radial flow is a unit for the regenerative reforming of hydrocarbon cuts of the gasoline type, which can be defined as having a distillation interval of between 80 and 250°C. But the field of application of the present invention is broader, and in addition to the catalytic reforming of gasolines, we can cite the skeletal isomerization of various olefinic cuts in O4, O5, or the metathesis process for the production of propylene, for example. This list of processes is not exhaustive, and the present invention can be applied to any type of catalytic process with radial flow and gaseous feedstock. Thus, in the context of new energy technologies, processes for the dehydration of alcohol to alkenes, for example, can use this type of technology.

Patent EP3064268 discloses a collection assembly for a gaseous fluid capable of being arranged in a moving catalyst bed reaction section of a radial reactor, said collection assembly comprising a vertical cylindrical grid permeable to the gaseous fluid and impermeable to the catalyst particles, and a vertical cylindrical tube supported by said grid and arranged concentrically with respect thereto. The tube, permeable to the gaseous fluid and impermeable to the catalyst particles, comprises one or more zones permeable to the gaseous fluid comprising a plurality of through-holes and a plurality of zones with reduced permeability to the gaseous fluid relative to the zone permeable to the gaseous fluid. Each zone with reduced permeability has a lower porosity than that of a so-called permeable zone. The porosity of a zone is defined by the ratio between the total permeable surface area of said zone and the total surface area developed by said zone. According to the teaching of this patent, the porosity of a zone with reduced permeability is between 0 and 0.005, it being understood that a zone of reduced permeability excludes any space between the through holes of the permeable zone(s).

This design of the collection means with a perforated tube having one or more zones with reduced permeability associated with the grid is very interesting, because it allows to control the pressure drop at the grid: by playing on the porosity of the perforated tube, it is possible to generate different pressure drops over the height of the collection grid and therefore to adapt the pressure drops according to this height. In addition, it turned out that the presence of these zones with reduced permeability on the tube also makes it possible to reduce the blockage of the catalyst against the grid compared to a simple grid without an associated tube.

However, this design is still subject to improvement. Indeed, the design of the collection means to be integrated into the reactor, in particular the way in which the tube is perforated, is specifically adapted to a single type of hydrocarbon gaseous reagent, depending on the desired conversion and the operating conditions targeted for this (temperature, pressure, flow rate, etc.).

However, one may want more flexibility in the collection mode. Indeed, one may need to operate the radial type reactor with several different incoming fluids or according to different operating modes, while the combination of the grid and its high-performance tube responds optimally to a type of gas/to a reactor operating point.

The aim of the invention is therefore to develop a means of collecting gaseous effluent from a radial type reactor which is improved, and which, in particular, makes it possible to operate satisfactorily with at least two types of reactant/gaseous effluent and/or with at least two different operating points.

Summary of the invention

The invention firstly relates to an assembly for collecting a gaseous fluid capable of being arranged in a reaction section comprising a catalyst bed of a radial reactor, said reactor being arranged along a longitudinal axis, said collection assembly comprising a tubular grid, in particular cylindrical, intended to be arranged along said longitudinal axis, said grid being permeable to the gaseous fluid and impermeable to the catalyst particles, such that said collection assembly also comprises:

- an external collection tube, preferably cylindrical, and

- an internal collection tube, preferably cylindrical, said internal tube being arranged in the external tube, itself arranged in the grid tubular, said tubes and said grid being arranged along the same axis, each of the inner and outer tubes having openings to be permeable to the gaseous fluid and impermeable to the catalyst particles, the space between the two outer and inner tubes forming a first collection zone and the space in the inner tube forming a second collection zone, each of the collection zones being closed at one of its longitudinal ends and opening at the other of its longitudinal ends into a gaseous effluent outlet means which is equipped with a removable closure means, said removable closure means having at least one open position and one closed position of said outlet means.

This collection assembly is thus an improvement of that described in the aforementioned patent EP3064268: by providing for the insertion of not one but two gas-permeable tubes into the cylindrical grid, the collection assembly according to the invention differentiates two separate collection zones, which can be operational alternately depending on whether the associated closure means is in the open or closed position. Each of the collection zones can thus be sized and designed to collect a given type of gaseous effluent optimally.

This is very advantageous, particularly in the case where the reactor is a reactor intended to convert by catalytic reaction a feedstock into the form of a hydrocarbon gas(es), but where it also undergoes periods of in situ regeneration of its catalyst by flow through the catalytic bed of a regeneration gas, which is generally not based on hydrocarbons, and which is for example oxygen O2, hydrogen H2, nitrogen N2, water H2O or carbon dioxide type CO _X : the hydrocarbons on one side, the regeneration gas on the other, have very different chemical characteristics, different densities, in addition, possibly, different physical quantities (temperature, pressure, etc.), therefore different flow properties.

Another scenario can also be encountered, which is where the reactor can alternatively process by catalytic conversion hydrocarbon-type feedstocks which are different, either by their composition or by at least one physical quantity (temperature, pressure, flow rate, etc.).

Another scenario can also be encountered, which is where the reactor is a reactor dedicated to catalyst regeneration, with the need to operate with several types of gas successively. However, until now, we have sought to optimize the design of the radial reactor, to allow as homogeneous a distribution as possible of a gaseous fluid in the reactor, the one which is mainly the one treated by the reactor. In the case of a reactor for the conversion of a hydrocarbon(s) type feedstock with in situ regeneration, the design of the reactor, and in particular of its gaseous effluent collection system, will be carried out specifically to optimize the distribution of this feedstock and the effluent resulting from its catalytic conversion. Concretely, we will choose the appropriate sizing of the various components of the reactor to control the overall pressure drop of the gas to be treated/converted in the reactor. To do this, we will, for example, size the size of the collection zone, the permeability level of the distribution grid and the permeable collection tube inserted in said grid.

It is then understood that if the reactor design has been adjusted for a specific load, called the main load, if the incoming gas is changed, for example if we switch to a regeneration gas or to another load called an alternative, the reactor design is no longer optimal for this gas different from the main load, because their flow properties differ greatly. In fact, when the reactor is supplied with another gas, such as a regeneration gas, it may be necessary to significantly increase the flow rate of this regeneration gas to maintain its homogeneous distribution across the catalytic bed, which is expensive, and requires storing a significant quantity of this regeneration gas on the production line, which is not desirable.

The solution of the invention is both simple and effective: with two distinct collection zones, the design of which can be differentiated, we will be able to have two optimal operating points, for two different loads and not just one. And the addition of an additional collection zone made in the invention does not complicate, or not significantly, the design and the operating mode of the reactor, since it is enough to add an additional tube to the known collection system, to create these different collection zones, while keeping the same overall dimensioning for the collection assembly.

It should be noted that the collection assembly may provide not two collection zones, but three or more: it is then planned to add one or two more permeable tubes in the volume delimited by the tubular grid, so as to have a series of three or four tubes oriented along the same axis, and preferably coaxial: there will then be a first collection zone defined by the volume of the innermost tube, and several successive annular collection zones delimited by the volumes between two adjacent tubes. The design of such a collection assembly will be more complex but will allow its operation to be adjusted not not two types of gas, but three or four. These additional tubes can also be provided for to be removable, and added or removed as needed.

It should also be noted that the tubular “grid” within the meaning of the invention includes in its definition a simple grid, but also any similar component (grid in the strict sense or conduit provided with openings).

It can also be emphasized that the invention according to the invention can be implemented either in new reactors, or in reactors already operational and to which a component of the collection system is added, or in which a conventional collection assembly is replaced by a collection assembly according to the invention.

Advantageously, the tubular grid, the outer tube and the inner tube of the invention are arranged coaxially and are all cylindrical, the first collection zone being in fact annular and the second collection zone being cylindrical. This embodiment is the simplest, with a cylindrical shape for the three components, and collection zones of different geometric shapes.

The invention may provide for other embodiments, for example a section of at least one of the three components (grid, internal tube, external tube) which is not of round section, but oval for example, or of the same geometric shape as that of the reactor enclosure in which they are arranged, or whose section is not constant over all their respective heights (along their longitudinal axis).

The outer tube can be mechanically connected to the tubular grid, and the inner tube can be mechanically connected to the cylindrical grid and/or to the outer tube: with such a design, the three components are mechanically secured to make the collection assembly easier to place in the reactor, and to ensure that they are in fact well positioned relative to each other: they can be pre-assembled and then inserted as a unit into the reactor. Note that the mechanical connection can be achieved by permanent fixing means (welding, riveting) or removable means (mechanical locking/unlocking systems), the second case allowing one of the tubes to be replaced in the event of a problem without having to change all three components.

Advantageously, the sizing and/or the number and/or the distribution of the openings of the internal tube is/are different from those of the openings of the external tube. It is by modulating the different openings for the two tubes that we will in fact be able to adjust the appropriate pressure drop for each of the effluents which will be collected then drawn off from one or other of the collection zones, depending on its flow properties. Similarly, the respective volume/dimensioning of each of the collection zones can be adjusted. Thus, advantageously, it can be provided that the ratio of the internal diameter of the external tube to the internal diameter of the internal tube is at least 1.2, in particular at least 1.5 or at least 2 and preferably at most 4 or at most 3.

Preferably, the gaseous effluent outlet means are conduits (a conduit or a set of conduits, sections of which can be mounted in series or in parallel), and the removable closure means can be valves arranged in said conduits, which can be controlled manually and/or in an automated or semi-automated manner.

The invention also relates to a radial circulation reactor for gaseous fluid comprising:

- an external envelope forming an enclosure extending along a longitudinal axis, in particular vertical,

- a collection assembly for a gaseous fluid as described above, the tubular grid of which is arranged along said longitudinal axis in said enclosure, between the external casing and the external tube, so as to define an annular distribution zone for the gaseous fluid between the casing and the tubular grid and an annular catalytic zone with a catalyst bed between the cylindrical grid and the external tube;

- gaseous fluid inlet means in fluid connection with the annular distribution zone;

- a first gaseous effluent outlet means in fluid connection with one of the ends of the first collection zone and equipped with a first removable closure means;

- a second gaseous effluent outlet means in fluid connection with one of the ends of the second collection zone and equipped with a second removable closure means.

Preferably, in operation, one of the removable closure means is in the closure position when the other of the removable closure means is in the open position: thus, one or the other of the two collection zones can be “activated”, depending on the type of gas entering the reactor/leaving the reactor, by closing the gas outlet of one of them and opening the gas outlet of the other zone. The gas is thus “forced” to diffuse into the collection zone which has been designed specifically for it, so as to ensure the optimal pressure drop for the gas in question.

Advantageously, the reactor according to the invention comprises means for controlling the removable closure means, said means being manual, automated or semi-automatic. automated, in particular means in the form of computer/electronic devices, preferably in this case with a manual interface to be able to switch back to manual control if necessary.

Advantageously, the removable closure means can simply be valves, in particular solenoid valves, arranged in gaseous fluid outlet means in the form of conduits.

Preferably, the collection assembly according to the invention, including the tubular grid and the internal and external tubes, extends over at least 80% of the height of the annular catalytic zone, in particular its entire height, and preferably over at least 80% of the total height of the reactor enclosure.

The reactor according to the invention may be a fixed-bed catalytic hydrocarbon reforming reactor, or a reactor for dehydrating alcohols into olefins, or a reactor for regenerating a catalytic cracking or Fischer-Tropsch reaction catalyst.

Examples include catalytic reforming processes described in patents FR3014894, FR3090007 or FR3120076.

Examples include alcohol dehydration processes described in patents WO2013/011208 and WO2014/083260.

The invention also relates to a method for implementing the reactor described above, and according to which:

- a first gaseous fluid and a second gaseous fluid are alternately injected into the reactor, and, at each alternation,

- one of the removable closure means is moved from an open position to a closed position and the other removable closure means from a closed position to an open position, each of the gaseous effluents from the first and second gaseous fluids being collected by its collection zone and withdrawn by its outlet means.

There are thus two distinct collection modes, for two distinct types of gaseous effluents, so that the two types of effluent are collected and then withdrawn under the best conditions, even if they differ significantly in their properties/chemical nature. The reactor thus has (at least) two different operating phases, with two different collection modes, one of which can correspond to the catalytic conversion phase of a given gaseous charge, the other to the regeneration of the catalyst with a gas whose characteristics can be very different. As mentioned above, it is also possible to have not two but three or four separate collection areas, which then offers three or four different collection methods, and three or four different operational phases, the sequence of which can vary and adapt to needs.

The invention also relates to a method for implementing the reactor described above, and according to which: a first gaseous fluid is injected into the reactor enclosure passing through the catalytic zone from the distribution zone radially towards the center of the reactor, a) a first gaseous effluent is collected in a collection zone chosen from among the first and second collection zones, b) the first gaseous effluent is withdrawn after passing through one of the first and second collection zones by the outlet means in fluid connection with said collection zone, the removable closure means of which are in the open position, c) the injection of the first gaseous fluid is stopped, d) a second gaseous fluid is injected into the reactor enclosure passing through the catalytic zone from the distribution zone radially towards the center of the reactor, e) a second gaseous effluent is collected in a collection zone chosen from among the first and second collection zones and different from the collection zone chosen for step b) f) the second gaseous effluent is withdrawn gaseous effluent after passing through the collection zone of step f) by the outlet means in fluid connection with said collection zone, the removable closure means of which are in the open position.

In the method according to the invention, preferably, one of the removable closure means is in the open position, the other of said removable closure means is in the closed position: the gas to be withdrawn is therefore forced to pass through one or other of the collection zones with only one withdrawal outlet open at a time during operation of the reactor.

The first and second gaseous fluids can present:

- a different chemical composition, with in particular one of the gaseous fluids in the form of hydrocarbon compounds intended to be converted by catalytic reaction and therefore transformed at least in part into other hydrocarbon compound(s), and the other gaseous fluid being non-carbonated, in particular intended to regenerate the catalyst of the catalytic bed,

- and/or a different molecular structure, - and/or at least one different physical quantity, in particular a different temperature, pressure or flow rate.

The invention also relates to the use of the reactor described above for, alternately,

- convert by catalytic reaction a first hydrocarbon gaseous fluid, and

- regenerate the catalyst in situ with a second gaseous fluid, particularly non-hydrocarbon.

It should be noted that throughout this text, it is understood that there are one or more types of gaseous fluid entering the reactor, and that, within the reactor, at least one of these types of fluid is intended to be converted at least in part into another type of fluid: the gaseous fluid withdrawn from the reactor, called gaseous effluent, may therefore have a different composition/characteristics. Thus, a charge of gaseous fluid entering in the form of hydrocarbon compounds will then be withdrawn in the form of an effluent that may contain a portion of unreacted charge and one or more hydrocarbon compounds resulting from the catalytic reaction. Similarly, a regeneration gas containing, for example, incoming oxygen or hydrogen may then be withdrawn in the form of a gas depleted in oxygen or hydrogen, or in the form of a gas chemically modified due to its contact with the catalyst to be regenerated.

Therefore, the term gaseous fluid in this text can indifferently designate the incoming load or the outgoing effluent, depending on the context, unless otherwise specified; whether one or the other is considered, the invention applies to different characteristics between the two incoming gaseous fluids (incoming load) or between the two withdrawn gaseous fluids (effluent).

Other characteristics and advantages of the system and method according to the invention will appear on reading the following description of non-limiting examples of embodiment, with reference to the figures appended and described below.

List of figures

Figure 1 represents a perspective view with a partial section of a radial reactor according to a prior art.

Figure 2 represents a view of a section along a horizontal plane of a vertically oriented reactor and comprising the collection assembly of a radial reactor according to the invention. Figure 3 represents a sectional view of a first embodiment of a radial reactor comprising a gas collection assembly according to the invention, along a vertical plane passing through the longitudinal axis of the reactor.

Figure 4 shows a sectional view of a second embodiment of a reactor radial comprising a gas collection assembly according to the invention, along a vertical plane passing through the longitudinal axis of the reactor.

The figures are very schematic and do not necessarily respect the scale between the different components represented. Identical references from one figure to another refer to the same component.

The components are represented, unless otherwise specified, in the operating position of the reactor, the longitudinal axis of the reactor being vertical. The spatial indication terms of the type “top”, “bottom” are to be understood for a reactor positioned in this way.

Description of the embodiments

The invention aims to improve the design of the means for collecting/withdrawing gaseous effluents from so-called radial reactors, and in particular to improve the operation of these reactors when they switch from an operating mode aimed at converting a load to another operating mode aimed at treating another load or treating the catalytic bed with a particular gas in order to regenerate the catalyst particles, in particular in order to remove carbon deposits (this is then referred to as decoking the catalyst).

Indeed, with a single collection system, in regeneration operating mode, as the regeneration gas generally has very different characteristics from the feed gas/effluent from the feed gas, we are often led to have a regeneration gas consumption much higher than the consumption that would be sufficient to regenerate the catalyst: the reactors are designed to, in particular, minimize the pressure drop, so as to ensure a homogeneous distribution of the gas during the catalytic conversion. However, this optimal design for the catalytic reaction is not necessarily the most favorable when this same reactor is used for in situ regeneration of the at least partially deactivated catalyst, because this regeneration step uses a gas whose composition is different and which therefore has different properties in terms of flow.

The invention relates to a system for collecting a gas or a mixture of gases capable of being placed in a radial flow reactor of gaseous fluid comprising a fixed catalytic bed, and which will be able to collect and withdraw two different types of gas in an optimal manner for each of them.

The invention relates to a reactor which integrates this new collection system, and comprising a closed enclosure containing a fixed granular bed (such as for example a catalytic reactor, a catalyst regenerator or an adsorber containing a bed of a adsorbent compound), with radial flow, from the periphery towards the center of the enclosure, of a gaseous fluid through the fixed granular bed and comprising the collection system according to the invention. Preferably, the reactor according to the invention is implemented to carry out the catalytic conversion of a feedstock and the in situ regeneration of the catalyst.

It is, for example, particularly well suited for use in the following equipment: reactors for dehydrating alcohols into olefins, for example ethanol into ethylene; catalytic reforming reactors; fixed-bed hydrocarbon reforming reactors with in situ regeneration of the catalyst; catalyst regeneration reactors, for example catalytic cracking or Fischer-Tropsch, etc.

The collection system of the invention can therefore be applied in a reactor of a conventional oil refining unit, or a gas processing unit, or a biomass processing unit, or any other renewable fuel production unit.

Figure 1 represents a sectional view of a radial reactor with the collection system described in the aforementioned patent EP3064268. It represents a radial flow reactor 1 having the external form of a cylinder forming a cylindrical enclosure 2 extending along a vertical axis of symmetry AX. The enclosure 2 comprises in its upper part a first orifice 3 and in its lower part a second orifice 4. The orifices 3 and 4 are intended respectively for the inlet and outlet of a gaseous fluid passing through the reactor 1. It should be noted that the respective functions of the orifices 3 and 4 can be reversed, that is to say that the orifice 4 serves as an inlet orifice for the fluid and the orifice 3 is an outlet orifice for the reaction effluent.

Inside this cylindrical tank, a catalytic bed 7 is arranged having the shape of a vertical cylindrical ring limited on the inner side by a central collection assembly 8 retaining the catalyst but permeable to the gaseous fluid and on the outer side by a so-called "external" grid 5 either of the same type as the inner grid of the collection assembly 8, or by a device consisting of an assembly of grid elements in the form of shells 6 extending longitudinally, as shown in Figure 1. These grid elements in the form of shells 6 forming conduits are also known by the Anglo-Saxon name of "scallops". These conduits 6 are held by the tank and generally pressed against the inner face of the enclosure, parallel to the axis AX. The grid elements in the form of shells 6 are in direct communication with the first orifice 3 via their upper end to receive a gaseous feed flow. The gas flow diffuses through the perforated wall of the conduits 6, to cross the catalytic bed 7 by converging radially towards the center of the reactor 1. The feedstock is thus brought into contact with the catalyst in order to undergo chemical transformations, for example a catalytic reforming reaction and produce a reaction effluent. The reaction effluent is then collected by the central collection assembly 8 which is here in communication with the second orifice 4 of the reactor. The collection assembly 8 comprises a cylindrical grid 9 and a cylindrical tube 10 arranged in the space circumscribed by the cylindrical grid 9. The cylindrical grid 9 and the cylindrical tube 10 each comprising an open end and a closed end. The grid 9 which acts as a sieve is designed so as to be permeable to the gaseous fluid and retain the catalyst particles. The cylindrical tube 10, permeable to the gaseous fluid, is perforated and thus comprises through holes.

In operation, the gaseous fluid introduced into the first orifice 3 is distributed over the height of the reactor and then passes radially through the "external" grid 5, then radially through the catalytic bed 7 where it is brought into contact with the catalyst in order to produce an effluent which is subsequently collected by the assembly 8 and evacuated through the second orifice 4.

Over time, the catalyst becomes deactivated due to the poisoning of its active sites (coke deposition). Therefore, in order to maintain acceptable productivity, it is necessary to regenerate the catalyst in order to restore its activity. This operation is carried out by injecting a gaseous fluid or several regeneration gases (e.g. O2, H2, N2, CO, H2O, etc.) sequentially through the catalytic bed and possibly modifying the operating conditions of temperature and/or pressure.

As stated above, the design of a radial reactor allows for a homogeneous distribution of the gaseous fluid and therefore allows for efficient catalytic conversion by controlling the overall pressure drop in the reactor (particularly within the catalytic bed and at the collector). However, the pressure drop calculated (particularly at the collector) during the design of the reactor is not necessarily the optimal one for conducting in situ regeneration of the catalyst, which uses one or more so-called regeneration gases whose flow properties are different from the gas to be converted. Thus, during the regeneration phase, in order to maintain a homogeneous distribution of the regeneration gas within and over the entire height of the catalytic bed, it is sometimes necessary to drastically increase the gas flow rates to achieve the optimal pressure drop set during the design of the reactor, resulting in overconsumption of regeneration gas.

The invention provides a gas collection system which can be installed in a radial reactor in which at least two gases which have properties can circulate different flow rates. According to the invention, the pressure drop at the collection system can therefore be chosen/adapted according to the gas circulating in the reactor.

Figure 2 represents a horizontal section at mid-height of a reactor T which integrates a collection assembly for a gaseous fluid according to the invention. Only the components which differ from those shown in Figure 1 will be described in detail here, for the sake of brevity.

Here, the collection system comprises: a cylindrical grid 9 and a cylindrical tube called external 10 arranged in the space circumscribed by the cylindrical grid 9, in a manner similar to that of Figure 1. Here, another cylindrical collection tube called internal 11 is added which is arranged in the external tube 10 so that the grid 9, the external tube 10 and the internal tube 9 are arranged concentrically, aligned along the same vertical axis which is the longitudinal axis of the reactor. This assembly defines two collection zones: a cylindrical zone Z1 delimited by the internal tube 11, and a zone Z2 of annular shape which corresponds to the volume which is located between the external tube 10 and the internal tube 11. The tubes 10 and 11 each have a first and second end (not shown in Figure 2), and one of the two ends is closed and the other is capable of being open or closed depending on the operating phases.

Each outer and inner tube 10, 11 has openings (not shown) in its wall to allow the gaseous fluid to diffuse while retaining the catalyst particles. The size, distribution and number of these openings are adjusted so as to present the appropriate gas permeability for each of the two collection zones Z1 and Z2.

The inner tube 11 has a number of openings per unit of tube surface area and/or a size of openings different from those of the outer tube, so that the pressure loss generated at the level of the inner and outer tubes is different.

Figures 3 and 4 represent (sections along a vertical plane passing through the longitudinal axis) the reactor, according to two different embodiments of the outlet/withdrawal means fluidically connected with each of the two collection zones Z1 and Z2.

In Figure 3, the annular-shaped collection zone of the reactor T Z2 is closed at its upper end and opens at its lower end into a withdrawal conduit 12, while the cylindrical-shaped collection zone Z1 is closed at its lower end and opens at its upper end into a withdrawal conduit 13.

In Figure 4, the reactor 1' is different from the reactor T; the annular-shaped collection zone Z2 is still closed at its upper end and opens at its lower end into a withdrawal conduit 12, and this time the cylindrical-shaped collection zone Z1 is also closed at its upper end, and opens at its lower end into a 13' draw-off pipe.

In both embodiments, the withdrawal conduits 12, 13 or 13' are equipped with solenoid valves (not shown) which can block or completely open the conduits in question, either by automated control or by manual control. The choice of one or the other of the two configurations depends in particular on the size of the upper/lower part of the reactor.

Of course, it is also possible to provide two draw-offs from the top, with the two lower ends closed for zones Z1 and S2.

To ensure differentiated collection between two different effluents, one of the two withdrawal pipes 12 is closed while the other pipe 13, 13' is open.

The collection assembly according to the invention therefore makes it possible to optimize the pressure drop of the reactor required according to the operating phases of the reactor. In the context of the invention, the term "operating phase" is understood to mean a period of use of the reactor during which at least one of the following parameters has been modified compared to the previous period of use: nature of the gaseous fluid (chemical composition or molecular structure), temperature, pressure, flow rate of the gaseous fluid.

Thus, for example, a catalytic conversion operating phase is characterized in particular by the fact that the gaseous fluid that is introduced is chemically different from that sent during the catalyst regeneration phase (hydrocarbons vs O2). It should also be noted that the regeneration phase can include two or more operating phases. Thus, during catalyst regeneration, a first operating phase can be applied where a first regeneration gas (for example oxygen) is injected followed by a second operating phase where the catalyst is reduced in the presence of a second gas (for example hydrogen).

According to one embodiment, the pressure drop produced by the internal collection tube 11 is greater than that produced by the external collection tube 10, in particular at least 1.5 or at least 2 times or at least 3 times greater (and preferably at most 5 times).

The outer cylindrical tube 10 (and its associated collection zone Z2), i.e. close to the periphery of the reactor, is preferably used as a gaseous fluid collector during the catalytic conversion operating phase, while the inner cylindrical tube 11 (and its associated collection zone Z1) is used as a gaseous fluid collector during the catalyst regeneration operating phase. The reactor 1' comprising the fluid collection system according to the invention can be used solely as a catalyst regeneration reactor. Thus, the closing and opening of the external and internal collection tubes will be selected according to the different regeneration operating phases (e.g. according to the nature of the regeneration gas injected (H ₂ , CO, O ₂ , Cl ₂ , N ₂ , ...) and/or the temperature and/or the pressure.

The device according to the invention makes it possible to drastically reduce utility consumption: The device according to the invention is a substantial improvement of the collector according to the prior art of figure 1 thanks to the addition of a central collector optimized for the regeneration phases.

Dimensions and materials of the different components of the collection assembly according to the invention:

The diameter of the outer tube 10 according to the invention may typically be between 600 and 2000 mm, preferably between 750 and 1300 mm, inclusive. The length of the outer tube 10 covers the height of the catalytic bed 7 and may typically be between 1000 mm and 15000 mm, preferably between 2000 mm and 10000 mm.

The diameter of the inner tube 11 according to the invention may typically be between 200 mm and 1000 mm, preferably between 350 mm and 850 mm, inclusive. The length of the inner tube 11 covers the height of the catalytic bed 7, and may typically be between 1000 mm and 15000 mm, preferably between 2000 mm and 10000 mm.

The thickness of the grid 9, which is a perforated cylindrical plate, may be between 4 mm and 16 mm, preferably between 6 mm and 10 mm, terminals included.

The grid 9 and tubes 10 and 11 can be made from a perforated sheet metal whose perforation size is chosen to allow only the gas to pass through (and not the catalyst particles).

Examples

Comparative example 1 works with the collection system according to figure 1, with a single perforated tube inserted into the grid 9, and therefore a single collection zone.

Example 2 according to the invention operates with the collection system according to the invention, as shown in Figures 3 and 4.

The operation of a reactor according to the invention, as shown in Figure 3 or 4, is as follows: the reactor operates as a catalytic conversion reactor (first operating phase) then as an in situ catalyst regeneration reactor (second phase). operating), that is to say that the operating phases of conversion and regeneration take place in the same reactor without unloading the catalyst.

During an operating phase in catalytic conversion, the gaseous feed to be converted enters the reactor T from the top (opening 3) and is diffused via a feed diffuser 31. The gas is distributed uniformly in the outer annular space between the wall of the enclosure 2 and the grid 9, crosses the catalytic bed 7 radially and uniformly over its entire height, then the treated gaseous effluent is collected via the annular collection zone Z2. The gas is withdrawn from the reactor from the bottom of the reactor, via the conduit 12. During this operating phase, the other cylindrical collection zone Z1 is not in operation, that is to say the outlet 13 or 13' (figure 3 or 4) of this collection zone Z1 is closed for example by means of a valve (not shown). The radial reactor as well as the annular collection zone Z2 are sized for a certain range of flow rates.

During the in situ regeneration phase of the catalyst, which is carried out with a lower gas flow rate than that of the conversion phase, it is necessary, for optimum operation, to maintain the lowest possible pressure drop difference between the first operating phase and the second operating phase. To this end, the inner tube 11 is sized differently (for example with smaller openings and/or a smaller number of perforations per square meter) from the outer tube 10, in order to establish an additional pressure drop within the reactor T. In this case, the evacuation of the gaseous effluent by means of the annular collection zone Z2 is stopped: the evacuation opening of said zone, via the conduit 12, is closed so as to prevent the evacuation of the gaseous fluid through this collector, and, on the contrary, the conduit 13 or 13' into which the tubular collection zone Z1 opens is open: the gas is withdrawn either upwards (figure 3) or downwards (figure 4).

The example below relates to the burning of coke deposited on a catalyst in the form of trilobal extrudates of length approximately 4 mm and equivalent diameter of approximately 1.6 mm.

The characteristics of the radial reactors used to carry out the “decoking” of the catalyst are given in Table 1 below:

[Table 1]

In the case of the collection assembly according to the invention, the total perforated surface area of the internal collection tube 11 has been chosen to be less than that of the external collection tube 10.

The catalyst is subjected to combustion under oxygen (regeneration gas) under the conditions mentioned in Table 2 below, in order to ultimately obtain a completely regenerated catalyst (determined via an analysis of the regeneration effluent).

[Table 2]

It can be seen that the pressure loss of the outer tube 10 is approximately, at least, in relative terms, one and a half times, or at least two times, lower than that of the inner tube 11.

It can be seen that with Example 2 according to the invention, the catalyst decoking operation made it possible, compared to Comparative Example 1, to reduce oxygen consumption by approximately 50%. In addition to this saving, there is also a reduction in consumption of other utilities, in particular energy, in particular to operate the compressor necessary to supply the regeneration gas, and a reduction in the oxygen storage capacity on the production site.

Claims

Claims 1. Assembly for collecting a gaseous fluid capable of being arranged in a reaction section comprising a catalyst bed of a radial reactor (1’, 1”), said reactor being arranged along a longitudinal axis, said collection assembly comprising a tubular grid (9), in particular cylindrical, intended to be arranged along said longitudinal axis, said grid being permeable to the gaseous fluid and impermeable to the catalyst particles, characterized in that said collection assembly also comprises: - an external collection tube (10), preferably cylindrical, and - an internal collection tube (11), preferably cylindrical, said internal tube being arranged in the external tube, itself arranged in the tubular grid, said tubes and said grid being arranged along the same axis, each of the internal and external tubes having openings to be permeable to the gaseous fluid and impermeable to the catalyst particles, the space between the two external and internal tubes (10, 11) forming a first collection zone (Z2) and the space in the internal tube (11) forming a second collection zone (Z1), each of the collection zones (Z1, Z2) being closed at one of its longitudinal ends and opening at the other of its longitudinal ends into a gaseous effluent outlet means (12, 13, 13') which is equipped with a removable closure means, said removable closure means having at least one open position and one closed position of said outlet means. 2. Collection assembly according to the preceding claim, characterized in that the tubular grid (9), the external tube (10) and the internal tube (11) being arranged coaxially and being cylindrical, the first collection zone (Z2) is annular and the second collection zone (Z1) is cylindrical. 3. Collection assembly according to one of the preceding claims, characterized in that the outer tube (10) is mechanically linked to the tubular grid (9), the inner tube (11) being mechanically linked to the cylindrical grid (9) and/or to the outer tube (10). 4. Collection assembly according to one of the preceding claims, characterized in that the dimensioning and/or the number and/or the distribution of the openings of the internal tube (11) is/are different from those of the openings of the external tube (10). 5. Collection assembly according to one of the preceding claims, characterized in that the ratio of the internal diameter of the external tube (10) to the internal diameter of the internal tube (11) is at least 1.2, in particular at least 1.5 or at least 2 and preferably at most 3. 6. Collection assembly according to one of the preceding claims, characterized in that the gaseous effluent outlet means are conduits (12, 13, 13') and in that the removable closure means are valves arranged in said conduits, which can be controlled manually and/or in an automated or semi-automated manner. 7. Reactor (1’, 1”) with radial circulation of gaseous fluid comprising: - an external envelope (2) forming an enclosure extending along a longitudinal axis, in particular vertical, - a gaseous fluid collection assembly according to one of the preceding claims, the tubular grid (9) of which is arranged along said longitudinal axis in said enclosure, between the external casing (2) and the external tube (10), so as to define an annular gaseous fluid distribution zone between the casing and the tubular grid and an annular catalytic zone (7) with a catalyst bed between the cylindrical grid (9) and the external tube (10); - inlet means (3, 31) for gaseous fluid in fluid connection with the annular distribution zone; - a first outlet means (12) for gaseous effluent in fluid connection with one of the ends of the first collection zone (Z2) and equipped with a first removable closure means; - a second outlet means (13,13') for gaseous effluent in fluid connection with one of the ends of the second collection zone (Z1) and equipped with a second removable closure means. 8. Reactor (1', 1") according to the preceding claim, characterized in that in operation one of the removable closure means is in the closure position when the other of the removable closure means is in the open position. 9. Reactor (1’, 1”) according to one of claims 7 or 8, characterized in that it comprises means for controlling the removable closure means, said means being manual, automated or semi-automated, in particular means in the form of computer/electronic devices with manual interface. 10. Reactor (1', 1”) according to one of claims 7 to 9, characterized in that the removable closure means are valves, in particular solenoid valves, arranged in gaseous fluid outlet means in the form of conduits. 11. Reactor (1’, 1”) according to one of claims 7 to 10, characterized in that the collection assembly, including the tubular grid and the internal and external tubes, extends over at least 80% of the height of the annular catalytic zone, in particular over its entire height. 12. Reactor (T, 1”) according to one of claims 7 to 11, characterized in that it is a fixed-bed catalytic hydrocarbon reforming reactor or a reactor for dehydrating alcohols into olefins or a reactor for regenerating catalytic cracking or Fischer-Tropsch reaction catalysts. 13. Method for implementing the reactor (T, 1”) according to one of claims 7 to 12, characterized in that: - a first gaseous fluid and a second gaseous fluid are alternately injected into the reactor, and, at each alternation, - one of the removable closure means is moved from an open position to a closed position and the other removable closure means from a closed position to an open position, each of the gaseous effluents from the first and second gaseous fluids being collected by its collection zone (Z2, Z1) and drawn off by its outlet means (12, 13, 13'). 14. Method for implementing the reactor (T, 1”) according to one of claims 7 to 12, characterized in that: g) a first gaseous fluid passing through the catalytic zone is injected into the reactor enclosure (2) from the distribution zone radially towards the center of the reactor, h) a first gaseous effluent is collected in a collection zone (Z1, Z2) chosen from the first and second collection zones, i) the first gaseous effluent is withdrawn after passing through one of the first and second collection zones by the outlet means in fluid connection with said collection zone, the removable closure means of which are in the open position, j) the injection of the first gaseous fluid is stopped, k) a second gaseous fluid is injected into the reactor enclosure, passing through the catalytic zone from the distribution zone radially towards the center of the reactor, l) a second gaseous effluent is collected in a collection zone (Z1, Z2) chosen from the first and second collection zones, among the first and second collection areas and different from the collection area chosen for step b) m) the second gaseous effluent is withdrawn after passing through the collection zone of step f) by the outlet means in fluid connection with said collection zone, the removable closure means of which are in the open position. 15. Method according to the preceding claim, characterized in that, when one of the two removable closure means is in the open position, the other of said removable closure means is in the closed position. 16. Method according to one of claims 13 to 15, characterized in that the first and second gaseous fluids have: - a different chemical composition, with in particular one of the gaseous fluids in the form of hydrocarbon compounds intended to be converted by catalytic reaction, and the other gaseous fluid being non-carbonated, in particular intended to regenerate the catalyst of the catalytic bed, - and/or a different molecular structure, - and/or at least one different physical quantity, in particular a different temperature, pressure or flow rate. 17. Use of the reactor (T, 1”) according to one of claims 7 to 12 for, alternately, - convert by catalytic reaction a first hydrocarbon gaseous fluid, and - regenerate the catalyst in situ with a second gaseous fluid, particularly non-hydrocarbon.