Method for completely emptying a catalytic reactor by means of an articulated arm equipped with rotary spiral protuberances

Abstract

The object of the present invention is to a method for emptying a reactor (1) comprising one or more spent catalyst particle beds (3) and one or more dump tubes (2) that open to the reactor (1) at the bottom portion of the particle beds (3) or below the particle beds. The method comprises: - A first step of causing a portion of the catalyst bed (3) to flow out of the reactor through the dump tube (2); then - A second step of driving the catalyst particles remaining in the reactor (1) at the end of the first step toward the opening (9) of the dump tube (2) to discharge the remaining catalyst (3') from the reactor (1) - This step is performed through a removable device introduced into the reactor through the dump tube - In the above method including, The above-mentioned removable device is characterized by including an articulated arm having one or more protrusions (8) arranged spirally around a rotation axis (6).

Description

Technology Field

[0001] The present invention relates to a method for completely emptying a reactor containing spent catalyst particles.

[0002] The method according to the present invention is particularly suitable for completely emptying industrial reactors containing spent catalyst particles. Background Technology

[0003] In particular, numerous industrial methods in the chemical, petrochemical, and refining sectors use solid catalysts in the form of small particles.

[0004] These catalyst particles are generally placed in a reactor in the form of one or more overlapping beds (or catalyst layers) that are stacked on support trays.

[0005] During use in the reactor, the catalyst gradually becomes deactivated and its activity decreases, so it must be recovered from the reactor to be replaced with a new active catalyst. Therefore, industrial reactors must be shut down periodically to renew the catalyst bed or the beds. This operation consists of two stages: emptying the reactor and recovering the spent catalyst from it, and then recharging it with an active catalyst. For obvious economic reasons, these two operations must be performed as effectively and quickly as possible to minimize reactor downtime.

[0006] Furthermore, the emptying process must be completed to completely remove the entire spent catalyst from the reactor. In practice, incomplete emptying can leave the spent catalyst in the reactor at the expense of the active catalyst, which is detrimental to the efficiency of the device and is practically unacceptable.

[0007] Nevertheless, completely emptying spent catalyst particles contained in industrial reactors is a tricky and problematic task for various reasons.

[0008] First, spent catalyst particles are sticky and tend to aggregate quite strongly with one another; since these aggregates tend to stick to the reactor walls, removing them from the reactor is quite complex.

[0009] Second, spent catalysts often contain an active phase that can react upon contact with air, such as an active phase containing metal sulfides, for example. Due to the presence of these compounds, spent catalysts may spontaneously self-heat very suddenly and to a significant extent, or in some cases, self-ignite upon contact with air. Most of these catalysts are classified as self-heating or flammable according to UN standards.

[0010] Therefore, handling spent catalysts can be tricky and dangerous, and reactor emptying is generally performed under an inert atmosphere (typically nitrogen).

[0011] A number of techniques described below for emptying reactors containing spent catalyst particles are known in the prior art.

[0012] Emptying Gravity Flow:

[0013] This is done by opening a side dump tube located at the bottom of the reactor (or the bottom of each catalyst bed in the case of a multilayer reactor), allowing the catalyst to flow out of the reactor under the action of its weight. In the most advantageous cases, this makes it possible to extract 80 to 85% of the spent catalyst contained in the reactor.

[0014] However, spent catalysts are generally sticky and may not flow well or at all, especially when aggregates of the spent catalyst form. In this case, it is necessary to rely on various techniques to separate the bed to move the flow of catalyst particles.

[0015] In any case, even in the most favorable circumstances, at the end of the gravity flow emptying operation, an amount of spent catalyst remains in the reactor, generally representing 15 to 20 weight percent of the initial catalyst bed, and in the best case, corresponding to the natural angle of inclination of these divided solids. This catalyst residue remaining in the reactor at the end of the gravity flow is generally referred to as "dig out" when the free-flowing catalyst is emptied. The volume of catalyst corresponding to the dig out depends on the geometry of the reactor and the natural angle of inclination of the catalyst particles. However, in the least desirable cases, the catalyst residue may additionally form within the columnar clusters or cavities of the reactor, as disclosed later.

[0016] In any case, human intervention is often required to remove residual catalyst: a worker descends into the reactor and manually removes this residue toward the dump tube, for example, using a shovel. This operation is particularly dangerous: given the self-heating nature of the spent catalyst, the reactor is in a nitrogen state, and fatal accidents occur regularly during such operations. Therefore, industrialists currently want to limit or completely eliminate such human intervention inside the reactor.

[0017] Suction emptying:

[0018] Generally, this is performed at the top of the reactor. The top of the reactor is opened, and under a nitrogen sweep, the charge distribution trays on the bed are disassembled, and the catalyst bed is sucked out through an industrial extractor with nitrogen compensation.

[0019] The extractor head is typically guided by an operator to empty the catalyst layer by layer. Solids and gases are separated through a cyclone. This widely used technology has several disadvantages: high cost; degradation of catalyst particles, sometimes to the point where it is impossible to regenerate them for later use; and the presence of an operator in the reactor, at least for finishing operations, which creates safety issues such as those described above.

[0020] Examples of this type of technology are described in US 7,959,870 and WO 2004 / 058572.

[0021] Wet gravity emptying:

[0022] This somewhat experimental and less commonly used technique can prevent human intervention in a reactor under an inert atmosphere. It consists of filling the reactor with water and emptying the catalyst / water mixture through a side dump tube located at the bottom of the reactor.

[0023] Nevertheless, there are the following major drawbacks: it generates a large amount of dirty water and impairs the potential to regenerate spent catalysts later, considering reuse.

[0024] Therefore, for a long time, there has been a need for an innovative solution capable of completely, quickly, effectively, and safely emptying industrial reactors of spent catalyst particles.

[0025] In application EP 3 108 959, the applicant proposed a method for emptying a reactor comprising a dump tube in the bottom portion. This method consists of two steps: a first step of allowing a certain percentage of the catalyst bed to flow out of the reactor under gravity through the dump tube, and a second step of extracting spent catalyst particles remaining in the reactor at the end of the first step using a flexible and movable extraction sleeve provided on a protruding outer surface, which is introduced into the reactor through the dump tube.

[0026] Application EP 3 108 958 in the applicant's name describes an alternative method, wherein the second step is performed by discharging the remaining catalyst from the reactor using a removable device comprising at least one rotary brush fixed to the end of an articulated arm introduced into the reactor through a dump tube.

[0027] Nevertheless, although these two methods are very effective, they are not entirely satisfactory, especially when the spent catalyst does not flow freely during the first stage of gravity flow emptying. In fact, if the spent catalyst particles tend to stick together and clump, the remaining catalyst does not take the form of a homogeneous volume with a dig-out shape, but rather has protrusions and / or cavities. For example, the formation of pillars and / or caverns is observed in the volume of the remaining catalyst at the end of the first stage, which can substantially complicate the implementation of the techniques described above.

[0028] Attached Fig. 1 shows a gravity flow emptying step in an industrial reactor containing a bed of spent catalyst particles. Attached Figs. 2 through 4 show three configurations of the residual catalyst volume at the end of this gravity flow emptying step.

[0029] FIG. 1 shows a column-shaped industrial reactor (1) comprising a bed (3) of spent catalyst particles. The reactor (1) includes a downwardly inclined dump tube (2) having an angle of inclination of approximately 45 degrees relative to the vertical. The tube (2) opens into the reactor (1) at the bottom portion of the particle bed (3).

[0030] In order to implement gravity flow emptying, the dump valve (7) is opened to open the dump tube (2), allowing catalyst particles to flow out of the reactor (1) by gravity flow through the tube (2).

[0031] The dotted line (4) indicates the initial upper level of the catalyst bed (3) before gravity flow begins, and the arrow in Fig. 1 indicates the direction of flow of the catalyst.

[0032] FIG. 2 illustrates a reactor (1) at the end of a gravity flow emptying step in which the catalyst flows freely. This figure shows that at the end of this step, a volume (3a) of spent catalyst remains in the reactor (1), which represents about 15 weight percent of the initial catalyst bed and corresponds to the natural angle of inclination of the catalyst particle clusters and cannot be removed by simple gravity flow emptying. The volume of the residual catalyst (3a) is homogeneous and corresponds to a conventional form of "dig out."

[0033] As illustrated in FIG. 3, when the catalyst does not flow freely due to gravity, the volume of residual catalyst (3b) may have protrusions formed by catalyst aggregation. FIG. 3 shows a columnar protrusion, which is a typical shape, but in reality, protrusions of all shapes and dimensions can be observed.

[0034] FIG. 4 shows another configuration that can be obtained even when the catalyst does not flow freely due to gravity. In this figure, the volume of residual catalyst (3c) has protrusions or cavities formed in the catalyst mass due to the catalyst particles aggregating together and adhesion to the reactor wall.

[0035] The technology proposed in the prior art does not always make it possible to satisfactorily handle cases where the volume of residual catalyst has protrusions and / or cavities as exemplified in FIGS. 3 and 4.

[0036] In particular, removable devices such as those proposed in EP 3 108 958 and EP 3 108 959 are not always able to break up catalyst aggregation and overcome protrusions such as pillars.

[0037] Furthermore, if a removable device is capable of effectively breaking off protrusions and / or removing cavities of the catalyst mass, catalyst particle clusters may detach and fall onto the device, becoming completely or partially buried and potentially blocking operation or even damaging it. In such cases, human intervention inside the reactor is generally required to remove the device, unblock it, and, where applicable, repair it.

[0038] The applicant has now discovered a new technology for emptying a reactor containing spent catalyst particles, which can solve the disadvantages described above.

[0039] Accordingly, the present invention is an improvement on the prior art that enables the reactor to be emptied very effectively of the entire load of spent catalyst, including cases where catalyst particles stick together and aggregate.

[0040] The object of the present invention is a method for emptying a reactor comprising one or more spent catalyst particle beds and one or more dump tubes that open to a bottom portion of the particle beds or to a reactor below the latter. The method comprises the following sequential steps:

[0041] - A first step of allowing a portion of the catalyst bed to flow out of the reactor through the dump tube; then

[0042] - A second stage of discharging catalyst residue out of the reactor by driving the catalyst particles remaining in the reactor at the end of the first stage toward the opening of the dump tube - this stage is performed by a removable device introduced into the reactor through the dump tube - .

[0043] This method is characterized in that the removable device comprises an articulated arm having one or more protrusions arranged spirally around a rotation axis.

[0044] The method according to the present invention enables the reactor loaded with spent catalyst to be emptied in a particularly complete, effective, and rapid manner, including cases where the latter aggregate with each other.

[0045] The method according to the present invention includes a first emptying step similar to that described in the prior art, but has the advantage of enabling complete emptying of the reactor in the process of the second step regardless of the composition of the volume of residual catalyst at the end of the first step, that is, whether the volume of such residual catalyst is homogeneous in the form of the conventional dig out (3a) or not. The method according to the present invention is completely effective, including cases where the volume of residual catalyst has protrusions (3b) and / or cavities (3c) as described above.

[0046] In particular, an articulated arm having one or more protrusions (hereinafter also designated as "rotational spiral protrusions") arranged spirally around a rotation axis enables reaching an aggregated catalytic region regardless of its configuration and breaking up such aggregates.

[0047] Catalyst clusters falling onto the rotating spiral protrusions do not hinder the latter from continuing rotational motion, and the spiral shape of the protrusions can remove catalyst clusters and remove the rotating parts. Therefore, the device according to the present invention can continuously operate and remove catalyst particles, including when they are embedded in a catalyst mass.

[0048] Therefore, the method according to the present invention can prevent human intervention inside the reactor and improve the safety of the operation for unloading spent catalyst.

[0049] Finally, the method according to the present invention preserves the characteristics of the spent catalyst and limits damage during unloading, which is essential when the catalyst needs to be subsequently regenerated for future use.

[0050] Other objects, features, aspects, and advantages of the present invention will become more apparent by reading the following description and referring to the drawings attached and described thereafter. Brief explanation of the drawing

[0051] FIG. 1 illustrates a gravity flow emptying step in an industrial reactor comprising a bed of spent catalyst particles, corresponding to the first step of the method according to the present invention. FIG. 2 shows the first configuration of the residual catalyst volume at the end of the gravity flow emptying step of FIG. 1 when the catalyst flows freely (conventional "dig out"). Figure 3 shows the second configuration of the residual catalyst volume at the end of the gravity flow emptying step of Figure 1 when the catalyst does not flow freely by gravity and the volume of the residual catalyst has a columnar protrusion. Figure 4 shows the third configuration of the residual catalyst volume at the end of the gravity flow emptying step of Figure 1, when the catalyst does not flow freely by gravity and there is a cavity in the volume of the residual catalyst. FIG. 5 illustrates the implementation of the second step of the method according to the present invention. Figure 6 is a cross-sectional view of Figure 5 according to section VI. Figure 7 shows a single continuous spiral winding for a rotating rod. Figure 8 shows a plurality of spiral protrusions that are continuously wound around a rotating rod. Figure 9 shows a plurality of spiral protrusions that are discontinuously wound around a rotating rod. FIG. 10 shows a plurality of spiral protrusions of variable dimensions that are continuously wound around a rotating rod. Figure 11 shows a plurality of spiral protrusions that are continuously wound around a visible axis of rotation. FIG. 12 shows a plurality of spiral protrusions of variable dimensions that are continuously wound around a visible axis of rotation. Figure 13 shows a spiral projection that winds around an unconcretized axis of rotation. Specific details for implementing the invention

[0052] In the following and at least one other indication, the limits of the value range are included within this range, particularly in the expressions "between" and "... to ... range".

[0053] Additionally, the expressions "at least one" and "at least" used in this description are equivalent to the expressions "one or more" and "more than", respectively.

[0054] The first step of the method according to the present invention consists of allowing a portion of the catalyst bed to flow out of the reactor through the dump tube by opening the dump tube.

[0055] This first step is preferably performed under gravity, that is, by allowing a portion of the catalyst bed to flow out of the reactor through the dump tube under gravity.

[0056] "Flow under gravity" means that the catalyst flows out of the reactor in the first stage under the action of its own weight, and is not pushed by mechanical pushing means inside the reactor (e.g., by an operator), nor is it sucked out of the reactor by particle extraction means.

[0057] This is a conventional gravity flow, as generally described in the prior art. The first stage is generally shown in Fig. 1 as described above.

[0058] Flow can also be supported, that is, in the process of the first stage, means to facilitate the removal of the catalyst from the reactor can be implemented, for example, by injecting pressurized gas into the reactor.

[0059] Furthermore, especially when catalyst flow does not occur spontaneously while the dump tube is open, one may rely on means to deagglomerate the catalyst bed immediately before the first stage. Such means are known in the prior art. In particular, this may involve the injection of a pressurized gas (typically pressurized CO2). Such means make it possible to initiate the flow of catalyst particles, and then, in the case of gravity flow, allow the catalyst to flow by the action of weight alone.

[0060] Accordingly, according to one embodiment of the present invention, the first step precedes a preliminary step of deagglomerating the catalyst, which is preferably achieved by injecting a pressurized gas, such as carbon dioxide or nitrogen, into the catalyst bed.

[0061] The present invention applies to a reactor provided with at least one dump tube that opens into the reactor at or below the bottom portion of the particle layer.

[0062] The dump tube may be horizontal or tilted downward. Preferably, it is tilted downward. In this case, the dump tube preferably has an angle of inclination in the range of 0 to 90 degrees relative to the vertical, and more preferably in the range of 20 to 70 degrees.

[0063] In the first step of the method according to the present invention, a generally significant proportion of the spent catalyst bed is extracted from the reactor, generally 30 weight % or more of the initial bed, generally 50 to 95 weight % of the initial catalyst bed, more particularly 60 to 90 weight % of the initial catalyst bed.

[0064] Subsequently, the remainder of the catalyst is completely removed from the reactor by the second step of the method of the present invention.

[0065] This second step implements a removable device comprising an articulated arm that supports one or more projections arranged spirally around a rotation axis, also known as rotary spiral projections. Advantageously, the rotary spiral projections or projections are positioned at the end of the articulated arm that is introduced into the reactor.

[0066] When the axis is set to rotation, the spiral protrusions or protrusions scrape off the catalyst clusters, ensuring that the catalyst particles are separated and discharged through the inlet of the dump tube.

[0067] Therefore, in this second stage of the process, the remainder of the spent catalyst is completely discharged from the reactor through the dump tube.

[0068] Protrusions or protrusions can have various shapes and dimensions within the same device. Similarly, the diameter and pitch of spirals or spirals can also differ within the same device.

[0069] The spiral protrusion or the axis of rotation on which the protrusions are arranged may or may not be materialized.

[0070] According to the first variation, the axis of rotation is not materialized, that is, it is not composed of a concretely visible element, such as, for example, part of the device. In this case, the spiral projections or projections are wound around a virtual axis (unless materially visible) and may have a shape similar to, for example, a corkscrew or a spring.

[0071] According to the second variant, the axis of rotation is embodied, that is, can be seen in the device. In this case, it may be reduced to a single line around which the spiral projections or projections are wound, or may consist of a rod of a somewhat significant diameter around which the spiral projections or projections are arranged.

[0072] According to a preferred embodiment corresponding to this second variant, the articulated arm includes a rotating rod having a spiral projection or projections disposed at its end.

[0073] "Rod" represents a cylindrical element in a manner known by itself. According to the present invention, the rod is of the rotary type, that is, rotates about a longitudinal axis.

[0074] The rod has a spiral-shaped protrusion, meaning it resembles the shape of a screw rod along all or part of its length.

[0075] According to a particularly preferred embodiment, the rotating rod having a spiral projection or projections has an auger shape along all or part of its length.

[0076] When the rod has multiple protrusions, they may be joined together or spaced apart along the rod.

[0077] The spiral formed by the winding of multiple protrusions can be continuous or discontinuous.

[0078] As well as the protrusions or protrusions, the rod, where applicable, may be composed of any suitable rigid material, such as rigid polymer materials, metallic materials (e.g., steel), composites, and mixtures of these materials, for example, in a non-limiting manner. The protrusions may be made of the same material as the rod, for example, obtained by the threads of the existing rod or otherwise not.

[0079] The shape and dimensions of the protrusions and, where applicable, the dimensions of the rods (especially diameter and length) depend on the size of the catalyst bed present in the reactor to be emptied and the type and somewhat aggregated state of the catalyst particles.

[0080] According to the present invention, a projection or projections arranged spirally about a rotation axis are present on an articulated arm, preferably at its end. This articulated arm is introduced into a reactor through a dump tube, which moves the rotational spiral projection in all possible directions inside the reactor, places it on a catalyst cluster, and, where applicable, allows the position to be adjusted by changing the angle between the rotation axis and the remaining articulated arm.

[0081] Therefore, the articulated arm can introduce and move the rotating spiral projection into the reactor and position it to come into contact with the residual catalyst to separate and remove it.

[0082] According to an advantageous embodiment, the articulated arm used in the present invention is telescopic and is composed of a plurality of modules assembled, for example by interlocking, immediately prior to the implementation of the method.

[0083] The device according to the present invention is removable and transportable. For the execution of the second step, the articulated arm is advantageously fixed to the dump tube.

[0084] The movement and position of the rotating spiral projection inside the reactor can be controlled by the guidance of an articulated arm. A guiding means is understood as any means that enables the articulated arm to move and position: a suitable guiding means may consist, for example, of a set of motors.

[0085] These guidance means can be controlled manually, automatically, or semi-automatically.

[0086] Where applicable, the joint angle between the rotating spiral projection and the remaining articulated arm can be controlled or left free.

[0087] When the control of the guiding means of the articulated arm is manual, an operator outside the reactor operates these guiding means to control the movement of the articulated arm inside the reactor.

[0088] When the control of the guiding means of the articulated arm is automatic, the guiding means is controlled by a computer that executes a program to move the articulated arm inside the reactor. The movement program can be predefined, meaning that the movement of the articulated arm in the second stage process is pre-calculated to optimize the removal of the catalyst residue. The movement program can also be designed to configure random movement of the articulated arm inside the reactor.

[0089] The control of the guiding means of the articulated arm can also be semi-automatic, that is, partially controlled by a computer program and partially controlled by an operator.

[0090] Similarly, the rotational speed of the spiral projection can be controlled manually, automatically, or semi-automatically by a motor as described above.

[0091] Furthermore, according to a particularly advantageous embodiment of the present invention, means for detecting the position of a rotating spiral projection or projections is present in the reactor. Such means can know the exact position of said projection in the reactor at any time and, where applicable, optimize movement and rotation speeds.

[0092] Such detection means may include computational software, which progressively determines the position of a rotating helical projection in the reactor given the movement of the articulated arm (simulation of the position of the rotating helical projection through software that compiles control data to infer the position).

[0093] Other detection means include, for example, a radar or ultrasonic detection system; a system implementing one or more accelerometers and one or more GPS; and a viewing system using one or more cameras.

[0094] According to a preferred embodiment, the detection means comprises one or more camera(s) that allow the position of the rotating spiral projection in the reactor to be viewed at any time. Such cameras may be located, for example, on the inner wall of the reactor and / or on an articulated arm. For this purpose, various types of cameras may be used, particularly night vision cameras, infrared cameras, etc.

[0095] Such cameras can enable the positioning of catalyst residues if necessary and, consequently, the movement and rotational speed of the rotating spiral projection.

[0096] The rotational speed of the rotating spiral protrusions or the protrusions may be fixed or variable. Preferably, it is variable, allowing it to be varied as the second stage proceeds. The rotational speed may also be adjusted in consideration of the size and composition of the catalyst aggregation.

[0097] FIGS. 5 and 6 illustrate an implementation of the second step of the method according to the present invention: the catalyst remainder (3') is discharged from the reactor (1) by a removable device comprising an articulated arm consisting of a first branch (5) connected by a joint (10) to a rod (6) on which a spiral projection (8) is disposed.

[0098] The rod (6) is rotated around an axis by the motor (9). In the embodiments of FIGS. 5 and 6, the motor is directly supported by the rod (6), but can be perfectly positioned in other locations, such as being transmitted to other elements of the device, for example.

[0099] The entire device is introduced into the reactor (1) through the dump tube (2).

[0100] The branch (5) allows the rotating rod (6) equipped with a spiral projection to be introduced deep into the reactor, and the joint (10) allows the rotating rod (6) to be moved in all possible directions within the reactor (1).

[0101] According to an unillustrated embodiment, the branch (5) itself may be articulated.

[0102] The movement of the branch (5) is ensured by a control unit (11) located outside the reactor (1), which allows the movement of the device inside the reactor (1) to be controlled manually, automatically, or semi-automatically.

[0103] The control unit (11) is connected to the branch (5) by an energy and information transmission element (e.g., hydraulic hose, electric cable, etc.). It may include various types of guiding means, such as electric or preferably manual. It may also provide the energy necessary to ensure the movement of the device and to power the motor (9). These guiding means may also enable the control of the joint (10) to control the angle of inclination of the rotating rod (6) relative to the branch (5). Alternatively, the joint (10) may be free.

[0104] FIGS. 7 to 12 illustrate various embodiments of the spiral projection (8).

[0105] FIG. 7 illustrates an embodiment in which a rotary rod (6) supports a single projection (12) having a continuous spiral shape. This figure corresponds to a particularly preferred embodiment in which the rotary rod has an auger shape.

[0106] FIG. 8 illustrates a variation of FIG. 7, wherein the rotating rod (6) supports a plurality of protrusions (13) joined together to form a continuous spiral around the axis (6).

[0107] FIG. 9 illustrates a modified example of FIG. 8 in which the projection (14) is discontinuously wound to form a discontinuous spiral around the axis (6).

[0108] FIG. 10 illustrates another variation of FIG. 8 in which the projection (15) has variable dimensions.

[0109] FIG. 11 illustrates an embodiment in which projections (16) are joined together and continuously wound around an axis (6') that can be seen but is reduced to a line.

[0110] FIG. 12 illustrates a modified example of FIG. 11 in which the projection (17) has variable dimensions.

[0111] FIG. 13 illustrates another embodiment in which a single projection (18) having a continuous spiral shape is wound around an unembodied axis (6) and has a shape similar to that of a corkscrew or a spring.

[0112] If the reactor comprises a plurality of catalyst beds, each bed can be emptied by the method according to the present invention. To do this, one or more dump tubes located at the bottom of each catalyst bed must be present in the reactor.

[0113] When the spent catalyst to be recovered from the reactor reacts with air, for example, when it has self-exothermic properties, the method according to the present invention is generally carried out by maintaining the reactor under an inert gas, that is, during the two steps according to the present invention, the catalyst recovered from the reactor is gradually replaced with an inert gas, for example, nitrogen. Introducing the inert gas into the reactor when the reactor is emptied can be performed, for example, at the top or bottom of the reactor.

Claims

Claim 1 A method for emptying a reactor (1) comprising one or more spent catalyst particle beds (3) and one or more dump tubes (2) that open to the reactor (1) at the bottom portion of the particle beds (3) or below the particle beds, comprising: a first step of causing a portion of the catalyst beds (3) to flow out of the reactor through the dump tubes (2); and then a second step of driving the catalyst particles remaining in the reactor (1) at the end of the first step toward the inlet of the dump tubes (2) to discharge the remaining catalyst (3a, 3b, 3c, 3') from the reactor (1)—this step is performed through a removable device introduced into the reactor through the dump tubes—in which the removable device comprises an articulated arm having one or more protrusions (8) arranged spirally around a rotation axis (6, 6', 6"). Claim 2 A method according to claim 1, characterized in that the first step is performed under gravity by causing a portion of the catalyst bed (3) to flow out of the reactor through the dump tube (2) under gravity. Claim 3 A method according to claim 1 or 2, characterized in that the projection or projections (8) arranged spirally around the rotation axis (6, 6', 6") are present at the end of the articulated arm. Claim 4 A method according to claim 1 or 2, characterized in that the rotation axis is embodied (6, 6'). Claim 5 A method according to claim 4, wherein the articulated arm comprises a rotating rod (6) having a spiral projection or projections (12, 13, 14, 15) arranged around it at the end. Claim 6 A method according to claim 5, wherein the rotating rod (6) having a spiral projection or projection (12) has an auger shape along all or part of its length. Claim 7 A method according to claim 5, characterized in that the rotating rod (6) has a plurality of protrusions that are joined together or spaced apart along the rotating rod (6). Claim 8 A method according to claim 1 or 2, wherein the device comprises a plurality of protrusions, and the winding thereof forms a spiral shape in a continuous or discontinuous form. Claim 9 A method according to claim 1 or 2, characterized in that the rotation axis (6) is not embodied, and the projection or projections (18) have a shape similar to a corkscrew or a spring. Claim 10 A method according to claim 1 or 2, characterized in that the movement and positioning of the rotating spiral projection (8) inside the reactor (1) during the second stage is controlled by the guidance of an articulated arm and is controlled manually, automatically, or semi-automatically. Claim 11 A method according to claim 1 or 2, characterized in that the articulated arm is telescopic and is composed of a plurality of modules assembled immediately before the implementation of the method. Claim 12 A method according to claim 1 or 2, characterized in that means for detecting the position of the protrusion or the protrusions is present in the reactor. Claim 13 A method according to claim 12, wherein the detection means comprises one or more camera(s) positioned on the inner wall and / or articulated arm of the reactor (1). Claim 14 A method according to claim 1 or 2, characterized in that the dump tube (2) is horizontal or tilted downward, and the angle of inclination relative to the vertical is in the range of 0 to 90 degrees. Claim 15 A method according to claim 1 or 2, characterized in that the first step is preceded by a preliminary step of deagglomerating the catalyst, which is achieved by injecting a pressurized inert gas, such as carbon dioxide or nitrogen, into the catalyst bed (3).

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