WO2007101928A2

WO2007101928A2 - Remotely controllable service module for aluminum production plants

Info

Publication number: WO2007101928A2
Application number: PCT/FR2007/000348
Authority: WO
Inventors: Benoît WARTELLE
Original assignee: E.C.L.
Priority date: 2006-03-03
Filing date: 2007-02-27
Publication date: 2007-09-13
Also published as: RU2008139310A; WO2007101928A3; FR2898137A1; FR2898137B1; CA2639893A1; EP1991719A2

Abstract

The invention concerns a service module (7) of a series of electrolytic cells designed for aluminum production by fused-salt electrolysis comprising a chassis (8) capable of being fixed on a carriage (6) moving along a mobile bridge (4) and equipped with a set of tools including in particular at least one anode handling member (11). The invention is characterized in that it is also equipped with at least two viewing means (41 and 42) for transmitting images captured as electromagnetic signals, typically two video cameras, said viewing means being spaced apart from each other and from the working zone, to be able to target the working zones in two non-parallel directions (D1) and (D2), preferably forming an angle of about 90° between them. Said service module can also comprise a third camera (43) which enables the tools and their working zone to be viewed as well as a fourth camera (44) fixed at the base of anode clamp actuators.

Description

REMOTE PILOTABLE SERVICE MODULE FOR ALUMINUM PRODUCTION PLANTS

TECHNICAL AREA

The invention relates to the production of aluminum by igneous electrolysis according to the Hall-Héroult method. It relates more particularly to remote control of "electrolysis service machines" (MSE) used in aluminum production plants.

STATE OF THE ART

Aluminum is produced industrially by igneous electrolysis, that is to say by electrolysis of alumina in solution in a bath of molten cryolite, called electrolyte bath, according to the Hall-Héroult process. The electrolyte bath is contained in electrolysis cells which comprise a steel box coated internally with refractory and / or insulating materials and a cathode assembly located at the bottom of the tank. Anodes, typically made of carbonaceous material, are fixed to a superstructure provided with means for moving them vertically, said anodes being consumed progressively during the electrolysis process. The assembly formed by an electrolytic cell, its anodes and the electrolyte bath is called an electrolysis cell.

The plants contain a large number of electrolysis cells arranged in line, in buildings called halls or electrolysis rooms, and connected electrically in series using connecting conductors, so as to optimize the ground occupation of the cells. factories. The cells are generally arranged in line so that vehicles can move along a traffic lane along the electrolysis room. They include a series of αnodes provided with a metal rod for fixing and electrical connection of the anodes to a metal anode frame secured to the superstructure.

In operation, an electrolysis plant requires interventions on the electrolysis cells including, in particular, the replacement of spent anodes with new anodes, the removal of liquid metal from the cells and the removal or addition of electrolyte. In order to carry out these interventions, the most modern plants are equipped with one or more service units including a movable bridge that can be moved over the electrolysis cells, and a trolley that moves along the bridge and on which is fixed a service module comprising handling and intervention devices (also called "tools"), such as shovels and hoists. The service module is placed above the area of the cell on which the intervention is to be performed and the tools are brought, typically using telescopic arms, to the actual working area along a path that includes a substantially vertical component downward. Subsequently, we will denote by X the direction of the long side of a cell, Y the direction of the short side of the cell and Z the vertical direction. Said service units are often referred to as "electrolysis service machines" or "M.S.E" ("PTA" or "Pot Tending Assembly" or "PTM" or "Pot Tending Machine" in English).

Anode change operations currently require the presence of two operators:

> an operator who controls the mobile bridge and the MSE tools from an on-board cabin; said onboard cabin is generally integral with the MSE: it moves with the MSE and can be put in place so that it is in front and overhanging the anode to replace, the operator being in direct visual access from the work area;

> and a ground operator who performs all the delicate or impossible tasks to perform from the cabin, for example because of insufficient visibility or technical difficulties preventing remote control of a particular tool for a specific specific operation, This operator is exposed to multiple risks related to the proximity of the electrolysis cell and the presence of handling tools, including the MSE tools located in the vicinity of the work area,

Typically, during the change of the anodes, the operator in the onboard cabin uses: a) a stitcher attached to the MSE, which serves to break the crust of alumina and solidified bath which generally covers the anodes of the cell, b) a bucket scoop attached to the MSE, which serves to clear the location of the anode, after removal of the spent anode, by removing solids (such as pieces of crust and carbon and alumina ) that are there; c) one or more anode clamps attached to the MSE, which will be used to grasp and manipulate the anodes by their rods, in particular for the removal of spent anodes and the placement of new anodes in the electrolysis cell; In general, the operator on the ground, who sees the work area from another angle, helps the operator to perform these manipulations. In addition, the operator on the ground grasps a retractable duct, also attached to the MSE and which serves to introduce alumina and / or ground bath into the electrolysis cell, so as to reform a coating layer, after the installation of a new anode.

With a view to reducing operating costs and improving safety, research has been undertaken to carry out these operations. - AT -

a single operator who can act safely at a sufficient distance from the work area.

In European application EP 0 618 313 (TECHMO), there is provided a modular assembly for automatically replacing anodes. The latter comprises a movable bridge, two modules on trolleys that move along the bridge, each module being specialized for certain tasks, a service vehicle and a transport vehicle traveling each.

70 in a lane placed on either side of a row of cells. In this modular equipment, the service vehicle comprises a control cabin from which the handling and intervention operations can be steered. It is mentioned, without more precision, that this control booth may be equipped with a remote control system and a visual display system.

/ 5 camera.

The first tests attempted by the applicant have shown that the remote control of operations such as anode change could not be ensured with any means of visualization of the work area and o transmission of orders to the tools, because said means must obligatorily allow the operator to act with the necessary reactivity. For example, the means conventionally used in other technical fields, such as the remote handling of radioactive charges, respond to different constraints which do not correspond to the particular needs relating to the operations involved during the change of the anodes, in particular because of the need to intervene very quickly during these operations.

In addition, the modular assembly described in EP 0 618 313 involves an excessively specific configuration of the electrolysis room, with for example two circulation paths on either side of the row of electrolysis cells. In the application US2004 / 211663 (ALCOA), the objective is different: it is a question of measuring the heights of the anodes, For this, it is suggested, in a particular modality, to measure vertical distances with the aid of three digital cameras mounted on a mobile rigid arm,

In the context of the present invention, it is not a question of measuring precise vertical distances but of designing a device which makes it possible to replace the anodes remotely, which is easily adaptable to the majority W of the existing electrolysis workshops and which can operate reliably, with short response times, in the specific industrial context of an igneous electrolysis aluminum fabrication plant,

DESCRIPTION OF THE INVENTION

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A first object according to the invention is a service module of a series of electrolysis cells for the production of aluminum by igneous electrolysis comprising a frame adapted to be fixed on a moving assembly, typically a carriage moving along. a movable bridge, and equipped with a set of tools including including at least one anode handling member, characterized in that it is also equipped with at least two viewing means capable of taking pictures and to transmit them in the form of electromagnetic signals, typically two video cameras, said display means being placed on said service module so that they can aim at the working area of said one or more anode handling members under two directions D1 and D2 non-parallel, making between them an angle typically greater than 45 °, preferably close to 90 °. More precisely, according to the invention, a first display means is placed in such a way that it can aim at the working zone under the direction (DI) of a line 0 contained in a vertical plane (Vl) and a second means visualization is placed so that it can aim at the working area under the direction (D2) of a right contained in a vertical plane (V2), the planes (Vl) and (V2) not being parallel, their intersection being a vertical line crossing the working area, the vertical planes (Vl) and (V2) are between them an angle as large as possible, typically greater than 45 °, preferably between 60 ° and 90 °,

5

The service module according to the invention is provided with display means which make it possible to remotely control the tools with which it is equipped, without the need for an operator placed inside an on-board cabin secured to said service module. Indeed, if the operator remains in said cabin w of the service module, it can not materially perform urgent operations that must be performed by the operator on the ground. It is therefore necessary, as in EP 0618313, to control the operations from the ground, to be able to intervene on the cell in case of necessity, without being condemned to use a vehicle on the ground with on-board cockpit. But

/ 5 the operator on the ground must be able to have visual access to the work area at least as good as that offered to the operator who was in the cabin on board the MSE,

For all the operations involved during the replacement of the 0 anodes and which are currently piloted from the cabin on board the

MSE (breakage of alumina crust and molten bath around the anode; removal in the location left by the removed anode of solid pieces which may contain debris of crust, carbon and alumina; grasping and handling the anodes by their rod), it is important to have a good estimate of the distances in the space, that is to say as much horizontal distances as vertical distances. According to the invention, at least two display means are used which visualize the work area by aiming it from two different locations, each in a direction included in a vertical plane passing through the work zone.

The operator to appreciate the distances, to avoid collisions between the tools and to reach the objective with a good precision, Of all these operations, it is certainly the seizure of the anode rod which proves to be the most delicate operation to be performed and said viewing means are determined according to the invention in number, in positioning and in the direction of intended, in the first place to facilitate this operation.

The handling member which is intended for the handling and movement of the anodes is used in particular for the removal of spent anodes and the introduction of new anodes in the electrolysis cell. It generally comprises a clamp capable of grasping the anode. This is placed near the end of the stem of the anode to be grasped, then is closed on said end, the anode thus grasped can be lifted and transported outside the electrolysis cell, typically to be routed to the anode recycling facility. The anode handling gripper is typically provided with two gripping members which pivot about a common axis or about substantially parallel axes. The direction (P) of the common axis or parallel axes is substantially horizontal. These two members form a jaw which has an open configuration, in which the ends of said members delimit a typically downward opening and in which the upper end of the rod can be inserted, and a closed configuration, in which the ends of said bodies come in lateral support on the rod so that said rod is trapped and retained,

The ends of the gripping members of the jaw outline an outline which generally follows the shape of the section of the end of the anode rod. Generally, it is rectangular, one of the sides of the rectangle corresponding to the contact surface of the anode rod on the anode frame. When the clamp closes on the end of the rod, the direction (P) of the pivot axis of the gripping elements of the clamp is, or is oriented, in the direction of one (L) or the other (I) of the sides of the rectangular section of the rod,

In general, the anode clamp is designed with a fixed axis (P) relative to the frame. In this case, one of the directions DI or D2 is preferably substantially parallel to said axis, but if the anode clamp is designed to maintain a certain freedom of rotation about a vertical axis, the axis (P) is not fixed relative to the frame and it is in these conditions preferable to define the directions Dl and D2 not directly with respect to the frame but with respect to the electrolysis cell, which can easily be done since the service module must being in a precise position which is fixed relative to the moving assembly to which it is attached (typically the carriage) and which is oriented such that said service module is in proximity and overhanging the anode to be replaced before the tools are activated, Thus, the directions D1 and D2 can for example correspond substantially when the service module is set up to work on a given anode, the X and Y directions of large and small sides of the electrolysis cell.

Preferably, the viewing directions D1 and D2 of the two display means correspond substantially, when the MSE is set up to work on a given anode, to the directions (L) and (I) of the sides of the rectangular section of the rod. anode.

When the service module is provided with a single anode gripping member, each of the two viewing means is preferably placed in a vertical plane which, when the MSE is set up to work on a given anode, passes through a mediator of the rectangular section of the anode rod. Said visualization means, which we will call cameras later, are placed at a height as low as possible above the cell, preferably on or slightly above the level called "level of safety ", which defines an altitude above which any lower tool end must be when the MSE is to move above the electrolysis cells.

When the service module is provided with several anode gripping members, these when they are put in place to work on the anodes to be replaced, are aligned in the alignment direction of the anode rods which it - even coincides with the direction of the anode frame, that is to say the X direction of the long side of the electrolysis cell, to which is w substantially parallel one of the sides (L or I) of the rectangular section of the anode rod. In this case, one of the cameras is placed in the vertical plane which contains the direction of alignment of the gripping members and which coincides, when the MSE is set up to work on the anodes to be replaced, with the common mediating plane. aligned anode rods, which

/ 5 is itself parallel to the anode frame. The other camera is placed in a vertical plane substantially perpendicular to the previous one and passing through the center of gravity of the gripping members. The cameras are placed at a height as low as possible above the cell, preferably on or slightly above, typically one hundred millimeters, of the security level. Although located at a low height, they overhang several meters the working area, which allows for example the first camera (located in the common median plane of the anode rods) to view as much the nearest clip as the or the following anode clamps. To improve the visibility of the following clip (s), two possibilities are available: a) the first camera is shifted very slightly with respect to the alignment plane of the clamps; b) each anode coupling or stall is carried out in successive steps, starting with the anode farthest from the camera and progressively approaching the first camera. 0 Generally, the gripping members are moved vertically either by gravity or by using vertical telescopic arms. The first camera is then in the alignment of the vertical axes on which said gripping members are actuated and the second camera is placed perpendicularly to this alignment direction, in a vertical plane which typically passes in the middle of said gripping members,

The two cameras, attached to the service module but located in two places distant from each other and from the work area, must be able to aim, under two

W directions preferably substantially orthogonal, the working area that is to say the set of points corresponding to the possible low positions of said one or more gripping members of the anodes, the first camera can make a fixed shooting in site, in azimuth and zoom, defined once and for all as a function of all of said possible lower positions of said one or more

The second camera, located "in front" of the anode clamp (s), is preferably motorized in situ (rotation possible around a horizontal axis), in azimuth (rotation possible around a vertical axis), and zoomed so that different shooting conditions can be defined according to the operation to be performed, because the service module 0 is preferably also equipped with other tools and said second camera must also be able to visualize their work area, In general, the first camera as the second camera should be placed far enough from the active part of the tools to provide a high visibility in the scope of the tools. 5

The service module may be equipped with other tools, in particular: a) a breaker, which serves to break the crust of alumina and solidified bath which generally covers the anodes of the cell; b) a bucket shovel which serves to clear the location of the anode, after removal of the spent anode, by removing solids (such as pieces of crust and carbon and alumina) which 'find there; c) a hopper associated with a retractable conduit which serves to introduce alumina and / or ground bath into the electrolysis cell, so as to reform a coating layer, after the establishment of a new anode; d) a heavy lifting tool such as a hoist.

At least for the second camera, the precise shooting conditions (target area, scale) can be defined specifically during the manipulation by the operator or, preferably, be predefined according to the tool chosen by the operator. operator,

Typically, so that the second camera can easily observe all the tools of the service module, the angle of deflection in site is between -60 ° and + 60 ° with respect to the vertical plane passing through D2. Similarly, so as to follow the tool in its descent to the work area or on the contrary follow it during its ascent, especially when the clamp with the worn anode is raised, the deflection angle in site of the second camera is between 0 ° and - 80 ° relative to the horizontal plane. The zoom magnification factor of the second camera is advantageously between 1 and 25.

Preferably, the first camera is placed on the MSE in the vertical plane Pl which coincides, when the MSE is set up to operate on a given anode, with the plane of symmetry of the alignment of the anode rods, parallel to the anode frame. It is placed at an altitude substantially equal to that of the security level, typically equal to 3 meters, and located towards the outside of the most peripheral of the gripping members, typically at a distance horizontal of it_comprise between 1 and 3 meters, preferably close to 1 meter.

Preferably, the second camera is placed on the MSE in the vertical plane P2 which, when the MSE is set up to operate on a given anode, is perpendicular to the plane P1 and passes through the barycenter of the gripping members, at an altitude substantially equal to that of the security level, typically equal to 3 meters, and in a position which, relative to the center of gravity of said gripping members, is opposite to the face of the or tongs which corresponds, when the MSE is put in place for working on the given anode (s), on the face of the anode rod (s) which is intended to come into contact with the anode frame, typically at a horizontal distance from said barycenter of the gripping members .. between 2 and 4 meters, preferably close to 3 meters.

In preferred embodiments of the invention, the service module comprises a frame, typically a platform, adapted to be fixed to a moving assembly and at least one turret mounted on the frame so as to be pivotable in use around a vertical axis A. Said turret is equipped with a set of tools such as those described above. It can also be equipped with two cameras which are therefore in this case in a fixed position relative to the tools. But said cameras can also be placed on a second turret independent of the first, coaxial and external thereto, that is to say surrounding the first turret and rotatable about the same vertical axis A.

A single turret makes it possible to have a compact module, in which the tools are placed close to the axis of rotation of the turret, without greatly affecting the visibility. It also makes it possible to make the operations symmetrical, so that such a compact module can be used indifferently whatever the position of the cells with respect to the lateral sides of the electrolysis room and whatever the position of the anode to be replaced in the cell,

A module with two turrets is more difficult to design, more expensive, less compact but it allows to have better visibility and to move at least one camera relative to the tools so as to obtain a more favorable angle of view.

Optionally, the service module according to the invention comprises a third camera, placed not far from the second camera, intended to present an overview of the tools of the module and the working areas relating to each of these tools.

Optionally, the service module according to the invention comprises another camera, placed near the actuator of one of the anode gripping members, typically fixed on the base of the telescopic arm which actuates said gripping member, and an area that includes the low position of the or gripping members.

The images perceived by the cameras are transmitted as analog or, preferably, digital data to a system or set of signal processing systems which results in the creation of images displayed on screens placed outside the service module. . Advantageously, the service module is provided with a central image processing device connected, typically by shielded cables, to the cameras and which processes the images received so that it can associate them by grouping them in the form of a unique digital image ("layout"), which is then advantageously compressed under the standard formats of video image compression (MPEG, JPEG, ...). Advantageously, said central image processing device is associated with a transmitter which transmits the digital files associated with the video images (advantageously compressed) under form of electromagnetic waves, preferably by air, to receivers located outside the service module and equipped with screens.

In order to improve the security of the remote control of the service module, said central device for processing the images perceived by the cameras processes the signal so that a number identifying the service module with which it is associated is embedded in at least one zone, preferably peripheral, of the transmitted image and / or the transmitter - which transmits the digital files associated with the video images - transmits in a specific frequency or a plurality of frequencies, representative of the service module to which the transmitter is associated .

The invention also relates to a service machine comprising a movable element, typically a carriage, and a service module as described above.

The invention also relates to a service unit of an igneous electrolysis aluminum production plant which comprises a movable bridge and at least one service machine comprising a carriage capable of moving along said movable bridge and a module service according to the invention.

The invention also relates to the use of a service unit according to the invention for the interventions on electrolytic cells for the production of aluminum by igneous electrolysis, in particular to effect the change of the anodes,

The invention also relates to a system for assisting the control of handling and intervention operations on an electrolysis cell, typically intended for the replacement of anodes, said system comprising: a service unit itself comprising a service module and moving with the aid of motorized actuators, said service module being provided with tools actuated by motors, said service unit being provided with display means,

5> a control module provided with at least one monitor reproducing the image of the working area taken by at least one camera and

a control module able to transmit commands to the actuators of the service unit, characterized in that:

W a) said service module is a service module according to the invention provided with a device for processing the images perceived by the cameras associated with a transmitter emitting signals associated with the digital images in the form of electromagnetic waves, preferably Hertzian waves;

B) said control module is provided with a receiver adapted to receive said electromagnetic waves and at least one monitor which has at least the image of one of the two cameras with a minimum definition of 350 000 pixels, preferably, taking the standard 2: 3 format, with a minimum definition of 768 * 512 pixels, preferably 0 with a minimum resolution of 1024 * 768 pixels,

The size of the screen is essentially a matter of clutter of the control module and recoil offered to the operator. Typically, the monitor is a digital screen of diameter greater than 12 "and preferably at least 5 to 14".

Optionally, said monitor can also present at any time, on request, the image of the other camera with the same minimum definition.

More preferably, said monitor has a sufficient surface area to

30 simultaneously present the two images with the same definition, the whole αccole typically occupying a minimum diagonal of 17 ", preferably 20".

Of course, said device for processing the images perceived by the cameras may be a central device connected, typically by shielded cables, to the cameras and which processes the images received so that it can associate them by grouping them together in the form of an image. unique digital ("layout"), which is then advantageously compressed in a video image compression format (MPEG, JPEG, ...).

Advantageously, the transmission system between the transmitting device of the service module which transmits the video images and the receiving device associated with the monitor (s) of the control module is a spread spectrum digital transmission system, typically the modulation system. called COFDM (Coded Orthogonal Frequency Multiplex). The information is decomposed in coded digital form so as to distribute it over several orthogonal carrier waves. This creates sub-channels very close in frequency and the signals thus transmitted, which have a low probability of being disturbed all at the same time, are, after reception, digitally reprocessed so as to reconstruct the complete information. Such a system makes it possible to have response times of less than 200 ms, which enables the operator to react in time according to what he observes on the screen.

Indeed, for the remote control of the tools involved during the change of the anodes can be effected effectively, it is important not only that the operator has a perfect vision of the work area but also that there is no significant time lag between an event the image that represents this event on the screen and the signal that causes a corrective movement of the actuator of the tool: it is necessary that the operator can see any incident, he can have minimum time to react and that its order to correct the current manipulation is transmitted in time to the actuator. Now the applicant has found that a purely digital transmission resulted in a response time of the order of 500 ms or higher, which is insufficient vis-à-vis the operational constraints related to the replacement of anodes. On the other hand, purely analogue transmission allows much lower response times, but the applicant has found that, in the particular environment of an electrolysis cell, it is subjected to too many major disturbances, which makes it impossible to obtain a reliable remote control system. This is why the applicant has developed the solution described above which combines the speed of an analog transmission with the reliability of a digital transmission,

In one embodiment of the invention, the control module is also provided with a monitor allowing the view of the field filmed by the third camera, and / or a monitor allowing the vision of the field filmed by the fourth camera, associated with gripping members of the anodes and fixed near the base of the actuator of one of the gripping member. Preferably, the image of this third camera and that of the fourth camera are also transmitted with a sufficient definition, corresponding to a minimum of 350,000 pixels. In a preferred embodiment of the invention, the control module is provided with a screen of sufficient size to simultaneously provide three or four images, the first two each occupying a surface defined by a diagonal greater than or equal to 12 ".

Said control module is in the form of a housing provided with buttons, easily transportable. It controls the movement of the mobile bridge, the truck, the turret (s) of the service module, the cameras and the tools, preferably mounted on telescopic arms. It is equipped with an emitter device transmitting the commands to the various actuators. Some orders are directly related to an action pnrululiere of a tool, others can be induced by this action. For example, if the operator chooses a particular action to be performed by a given tool, the system can automatically trigger one or more operations-related commands, with a predefined setting of the viewing parameters, one or more cameras. cameras.

In one embodiment of the invention, said control module and said control module are installed in a vehicle that moves in the circulation aisle of the electrolysis room.

In another embodiment of the invention, the electrolysis room is equipped with a plurality of control modules located in fixed cabins each associated with a group of n cells (n typically between 2 and 10); the control module is carried by the operator who moves to the cabin associated with the cell concerned by the change of anode. The operator installs said control module in said cabin by connecting it so that the steering assistance system is made complete in said cabin and can thus operate.

The remote control devices of the control module are paired with the machines: a channel and an address are assigned to each command - actuator pair. The system for transmitting signals between the cameras and the monitors of the control module is not necessarily the same as the system for transmitting commands between the control module and the various actuators of the mobile bridge, the truck, the turrets, cameras, telescopic arms and tools. Indeed, the first system has to manage the transmission of a data stream considerably larger than the second, even if the orders of remote controls require some security which for example may result in some redundancy of information transmitted. We can therefore call for the transmission of remote controls to a "classic" system, preferably to avoid disturbances related to the particular environment of electrolysis.

However, in the case where a COFDM type system would be used for the transmission of the images, it appears advantageous to use it also to transmit the commands to the various actuators of the service unit (mobile bridge, trolley, service module: turret, cameras, telescopic arms and tools).

The subject of the invention is also a process for the anode change of an electrolysis cell intended for the production of aluminum by igneous electrolysis, in which at least one anode determined by a new anode is replaced using the system. piloting assistance according to the invention as described above.

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The invention is described in detail below with the aid of the appended figures.

FIGURES 0

Figure 1 illustrates a typical electrolysis room, seen in section, for the production of aluminum and comprising a service unit shown schematically.

FIG. 2 schematically shows a particular arrangement of the basic tools and three cameras of a service module according to the invention, seen from below,

Fig. 3 schematically shows the service module of Fig. 2 in side view. Example (Figures 1 to 3)

Electrolysis plants for aluminum production include a liquid aluminum production zone that includes one or more electrolysis rooms (1). As illustrated in Figure 1, the electrolysis room (1) comprises electrolysis cells (2) and at least one "service unit" or "service machine" (3). The electrolysis cells (2) are normally arranged in rows or rows, each row or line typically having more than one hundred cells. The cells (2) are arranged so as to clear a circulation aisle (31) along the electrolysis room (1). The cells (2) comprise a series of anodes (21) provided with a metal rod (22) for fixing and electrically connecting the anodes to a metal anode frame (not shown).

The service unit (3) is used to carry out operations on the cells (2) such as the anode changes or the filling of the ground bath supply hoppers and the AIF3 of the electrolysis cells. It can also be used to handle various loads, such as tank elements, pockets of liquid metal or anodes. The invention particularly relates to service units capable of performing the anode changes.

The service unit (3) comprises a movable bridge (4) which can be translated over the electrolysis cells (2) and a service machine (5) comprising a movable carriage (6) able to be moved on the moving bridge (4) and a service module (7) equipped with several handling and intervention devices

(10), such as tools (shovels, grippers anodes, also called anode clamps, biters, ...). The movable bridge (4) rests and circulates on raceways (30, 30 ') arranged parallel to each other and to the main axis of the hall (and the queue of cells). In the configuration geometry of this example, the direction of the main axis of the hall coincides with the direction (Y) of the short side of a cell, During the movement of the service module above the electrolysis cells, the tools are arranged on said service module so that their lower end is always above a certain height, corresponding to a security level (S).

The service module (7) comprises a frame (8) fixed on a carriage (ό) which moves along the movable bridge (4) (in the X direction of the long side of the electrolysis cell). This frame is equipped with a set of tools (10) including two anode handling devices (11 and IT) and four cameras (41, 42, 43 and 44) which make it possible to remotely view the working areas of said anode handling members in at least two directions (D1) and (D2) substantially perpendicular to each other,

The anode clamp (11) is in the form of a jaw whose ends of the pivoting elements form a contour which generally follows the square shape of the section of the end of the anode rod. The direction (D2) is chosen so that it is parallel to the direction (P) of the pivot axis of the grip elements of the clamp. In this way, the second camera (42) can see the forceps substantially from the front.

The service module is here provided with two anode clamps (11 and 11 ') which, when they are put in place to work on the anodes to be replaced, are aligned in the alignment direction of the anode rods which itself coincides with the direction of the anode frame, that is to say the X direction of the long side of the electrolysis cell, which is substantially parallel to the L side of the rectangular section of the anode rod, the viewing directions (D1) and (D2) of the two cameras (41) and (42) coincide, when the MSE is set up to work on a given anode, to the directions (L) and (I) of the sides of the section square of the anode rod. The first camera (41) is placed in the vertical plane which contains the direction of alignment of the anode clamps, or rather near (typically one hundred millimeters) of this plane to facilitate the vision of the farthest anode clamp (11 ') • This plan, which coincides, when the MSE is put in place to work on the anodes to be replaced, with the common median plane of the anode rods, parallel to the anode frame (not shown), substantially corresponds to the plane (Vl) which includes the first viewing direction (D1). The second camera (42) is placed in a vertical plane (P2) perpendicular to the preceding one and passing in the middle (110) of the anode clamps

W (11) and (IT), the second camera (42) aims at the working area in a direction (D2) in a vertical plane (V2) coinciding with (P2) or at a slight angle with it (case illustrated in FIG. 2), the cameras (41), (42) and (43) are placed at a height corresponding to the security level (S), typically three meters above the ground.

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The anode clamps (1 1 and 11 ') are moved vertically by vertical telescopic arms (1 1 1). The first camera (41) is then in the vertical telescopic arm alignment and the second camera (42) is placed perpendicular to this alignment direction, in a vertical plane 0 which typically passes through the middle (110) of the clips. The two cameras are set so that they can aim at least all the points corresponding to the possible low positions anode clamps.

The first camera (41) realizes a fixed shooting site, in azimuth and zoom, defined once and for all, The second camera (42), located "opposite" of the anode clamps, is motorized in azimuth ( possible rotation around a vertical axis), in situ (rotation possible around a horizontal axis) and in zoom so that different shooting conditions can be defined according to the operation to be performed,

30 The first camera (41) and the second camera (42) are placed far enough from the active part of the tools to provide a high visibility in the scope of the tools.

The service module is equipped with tools other than anode clamps; a) a breaker (13), b) a bucket shovel (12); c) a hopper (14) associated with a retractable conduit (15)

The second camera (42) can easily view all the tools of the service module. For this, in the particular geometrical configuration of the service module of this example, the angle of deflection in site of said second camera (42) is between -60 ° and + 30 ° (trigonometrical direction) with respect to the vertical plane P2 . Similarly, so as to be able to follow the tool in its descent to the work area or during its ascent, the angle of azimuth displacement of the second camera (42) is between 0 ° and - 80 ° by relation to the horizontal plane. The zoom magnification factor of the second camera (42) is between 1 and 25.

The first camera (41) is placed on the MSE in the vertical plane (P1) at an altitude substantially equal to that of the security level, typically equal to 3 meters, and located towards the outside of the most peripheral of the anode clamps. (11), typically at a horizontal distance (dl) thereof close to 1 meter,

The second camera (42) is placed on the MSE in the vertical plane (P2), at an altitude substantially equal to that of the security level, typically equal to 3 meters, and in a position opposite to that of the face (F) clamps which corresponds, when the MSE is set up to work on two given anodes, to the face of the anode rods which is intended to come into contact with the anode frame, at a horizontal distance (d2) from the barycenter (110) of the clamps close to 3 meters,

The images perceived by the digital cameras (41) and (42) are transmitted to a central image processing device connected by shielded cables to said cameras and which processes the images received so that it can associate them by grouping them in form. a single digital image. A number identifying the service module to which the central image processing device is associated is embedded in at least one peripheral zone of the image thus composed. This digital image is then compressed in the format

JPEG2000. The module is associated with a COFDM transmission system,

The service module (7) comprises a frame (8) and a turret (9) mounted on the frame so as to be pivotable in use about a vertical axis (A) and equipped with both cameras (41) and (42). ), in a fixed position relative to the tools. It also includes a third camera (43), placed not far from the second camera 42) and intended to continuously present an overview of the tools of the module and the work area. A fourth camera (44) is placed near the base of the actuator (111) of one of the anode clamps (11). It relates to an area (23) which includes the low positions of the anode clamps (11) and (I T).

The service module (7) is associated with a system for assisting the control of handling and intervention operations on an electrolysis cell, intended for the replacement of the anodes. Said system comprises the service unit described below. above, a control module provided with at least one monitor reproducing the image of the working area filmed by at least one camera and a control module transmitting orders to the actuators of the service unit. The control module is equipped with a 21 "monitor that simultaneously displays the images of the first two cameras (41 and 42) on a diagonal of 15". Each image is provided on a format of 1024 * 768 pixels.

The control module is also provided with a 17 "screen allowing simultaneous continuous vision of the fields filmed by the third and fourth cameras,

The control module is in the form of a housing with m buttons, easily transportable. It is used to control the movement of the mobile bridge, the trolley of the turret (s) of the service module, cameras and tools, preferably mounted on telescopic arms.

The transmission of commands to the various actuators of the elements of the service unit is ensured by a paired radio control system.

/ 5 conventional.

The electrolysis room is equipped with a plurality of control modules located in fixed cabins each associated with a group of 4 cells. The control module is carried by the operator who moves to the cabin associated with the cell concerned by the change of anode. The operator installs said control module in the cabin by connecting it so that the steering assistance system is made complete in said cabin and can thus function.

Claims

1. Service module (7) of a series of electrolysis cells for the production of aluminum by igneous electrolysis comprising a frame (8)

5 adapted to be fixed on a moving assembly, typically a carriage (ό) moving along a movable bridge (4), and equipped with a set of tools including in particular at least one anode handling member (11). ), characterized in that it is also equipped with at least two viewing means (41 and 42) able to take pictures and transmit them under

W form electromagnetic signals, typically two video cameras, a first viewing means being positioned so that it can aim at said working area under the direction (Dl) of a straight line contained in a vertical plane (Vl) and a second display means being positioned so that it can aim at said working area under the direction (D2) of a

/ 5 line contained in a vertical plane (V2) non-parallel to (Vl), the intersection of the planes (Vl) and (V2) being a vertical line crossing said working area, said vertical planes (Vl) and (V2) forming between them an angle typically greater than 45 °, preferably between 60 ° and 90 °.

0 2) Service module according to claim 1 wherein the one or more anode handling members are clamps provided with two gripping members pivoting about a direction (P) and in that one or the other of said directions D1 or D2 is substantially parallel to said direction (P). 5

3) Service module according to claim 1 characterized in that said directions (D1) and (D2) correspond substantially, when said service module is set up to work on a given anode, the X and Y directions of large and small sides of the electrolysis cell. 0 4) Service module according to claim 1 characterized in that said at least one anode handling member (11) is adapted to grasp an anode rod of rectangular section and in that said directions (D1) and (D2) of sight of the two display means correspond

Substantially, when said service module is set up to work on a given anode, to the directions (L) and (I) of the sides of the rectangular section of the anode rod.

5) Service module according to claim 1 characterized in that it is provided with W several anode gripping members (11 and 11 ') aligned, the first display means (41) being placed in the vertical plane ( Pl) which contains the direction of alignment of the gripping members, the second viewing means (42) being placed in a vertical plane (P2) substantially perpendicular to the preceding and passing through the W barycentre (110) of said gripping members.

ό) Service module according to any one of claims 1 to 5 wherein said viewing means is placed on or slightly above the security level (S), which defines the altitude above which 0 any end tool should be located when said service module is to move over the electrolysis cells.

7) Service module according to any one of claims 1 to 6 wherein the second viewing means (42) is motorized site, azimuth and zoom.

8) Service module according to any one of claims 1 to 7 characterized in that it also comprises at least one of the following tools: 0 a) a breaker (13); b) a bucket shovel (12); c) a hopper (14) associated with a retractable conduit (15); d) a heavy lifting tool,

9) Service module according to any one of claims 1 to 8 wherein said first viewing means (41) is located outwardly from the most peripheral (11) of the grippers (11 and 11 '), typically at a horizontal distance thereof between 1 and 3 meters, preferably close to 1 meter.

10) service module according to any one of claims 1 to 9 wherein said second display means (42) is placed on the P2 plane in a position which, relative to the barycentre (110) of said gripping members, is opposite to the face (F) of the one or more tongs which corresponds, when the MSE is put in place to work on the given anode (s), to the face of the anode rod or rods which is intended to come into contact with with the anode frame, typically at a horizontal distance from said centroid of gripping members between 2 and 4 meters, preferably close to 3 meters.

0 11) Service module according to any one of claims 1 to 10 characterized in that it comprises a frame, -typiquement a platform, adapted to be fixed to a carriage (6) and a turret mounted on the frame so as to be pivotable in use around a vertical axis (A), said turret being equipped with a determined set of tools (11, 12, 13, 14) and said two viewing means (41 and 42) .

12) Service module according to any one of claims 1 to 10 characterized in that it comprises a frame, typically a platform, adapted to be fixed to a carriage, a first turret mounted on the frame of 0 to can rotate in use about a vertical axis, said first turret being equipped with a set of tools, and a second turret which surrounds said first turret and which is rotatable about the same vertical axis, on which are fixed said two viewing means.

13) Service module according to any one of claims 1 to 12 characterized in that it comprises a third display means (43), placed not far from the second display means (42), said third display means being intended to present an overview of the tools of said service module and the working area of all the tools,

14) Service module according to any one of claims 1 to 13 characterized in that it comprises another viewing means (44), placed near the actuator (111) of one of the gripping members

/ 5 (11) anodes, typically fixed on the base of the telescopic arm which actuates said gripping member, and targeting an area (23) which comprises the low position of the gripping member (s).

15) Service module according to any one of claims 1 to 14 0 characterized in that the images perceived at least by the first and second cameras (41 and 42) are transmitted as analog data or, preferably, digital to a system or set of signal processing systems which results in the creation of images displayed on screens placed outside said service module.

16) Service module according to claim 15, characterized in that it is provided with a central image processing device connected to the cameras and which processes the images received so that it can associate them with them.

30 grouping as a single digital video image, which is then preferably compressed into a standard compression format video signal, and in that it is also provided with a transmitter emitting the signal associated with the single digital video image in the form of electromagnetic waves to at least one receiver located outside said service module.

17) Service module according to claim 16, characterized in that said central device for processing the images perceived by the cameras processes the signal so that a number identifying the service module with which it is associated is embedded in at least one zone, preferably peripheral, of the transmitted image and / or in that said transmitter transmits in a frequency or a plurality of specific frequencies identifying said service module.

18) Service machine (5) comprising a movable element, typically a carriage (6), and a service module (7) according to any one of claims 1 to 17,

19) Service unit (3) comprising a movable bridge (4) which can be translated over the electrolysis cells (2) and at least one service machine (5) comprising a carriage (6), capable of moving along said moving bridge and a service module (7) according to any one of claims 1 to 17.

20) Use of a service unit according to claim 19 for working on electrolysis cells for the production of aluminum by igneous electrolysis, in particular for effecting the change of the anodes.

21) System for assisting the piloting of handling and intervention operations on an electrolysis cell, typically intended for the replacement of anodes, said system comprising: a service unit itself comprising a service module and moving with the aid of motorized actuators, said service module being provided with tools actuated by motors, said service unit being provided with display means,

5> a control module provided with at least one monitor reproducing the image of the work zone taken by at least one visualization means and

W a) said service module is a service module according to any one of claims 1 to 16, provided with a device for processing the images perceived by the cameras associated with a transmitter emitting signals associated with the digital images in the form of 'electromagnetic waves;

B) said control module is provided with a receiver device capable of receiving said electromagnetic waves and at least one monitor which has at least the image of one of the two display means with a minimum definition of 350 000 pixels, preferably with a minimum resolution of 768 ^* 512 pixels, more preferably with 0 a minimum resolution of 1024 ^* 768 pixels.

22) Support system for controlling handling and intervention operations according to claim 21 wherein the transmission system between the transmitting device of the service module that transmits the video images and the receiving device associated with the (x) Monitor © of the control module is a spread spectrum digital transmission system, typically the digital modulation system known as Coded Orthogonal Frequency Multiplex (COFDM).

23) A steering assistance system for handling and intervention operations according to claim 21 or 22 wherein said monitor can also present at any time on request, the image of the other visualization means with the same minimum definition.

24) Assistance system for controlling handling operations and

5 of intervention according to claim 21 or 22 wherein said monitor has a sufficient area to simultaneously present the two images, the accretive assembly typically occupying a minimum diagonal of 17 ", preferably 20".

25) A steering assistance system for handling and intervention operations according to any one of claims 21 to 24 wherein said control module is also provided with a monitor for viewing the image of the image. set taken by the third camera (43), and / or a monitor allowing the vision of the image taken by the

/ 5 camera (44) associated with the anode gripping members, fixed near the base of the actuator of one of the gripping members.

26) A steering assistance system handling and intervention operations according to any one of claims 21 to 25 wherein 0 the control module is provided with a monitor of sufficient size to simultaneously provide three or four images , the images corresponding to the first two cameras (41 and 42) being each presented with a minimum definition of 350,000 pixels.

27) A steering assistance system handling and intervention operations according to any one of claims 21 to 26 wherein said control module is in the form of a housing provided with buttons, easily transportable and allowing to control the movement of the mobile bridge, the trolley, the turret (s) of the service module 0, the cameras as well as the tools. 28) assistance system for steering handling and intervention operations according to any one of claims 21 to 27 wherein, when the operator chooses a particular action to be performed by a given tool, the operation, with a predefined setting of the display parameters, one or more display means is automatically triggered.

29) system for assisting the piloting of handling and intervention operations according to any one of claims 21 to 28 in

/ o said control module and said control module are installed in a vehicle that moves in the circulation aisle (31) of the electrolysis room (1).

30) system for assisting the steering of handling and / or intervention operations according to any one of claims 21 to 29 wherein the electrolysis room (1) is equipped with a plurality of control modules located in fixed cabins each associated with a group of n electrolysis cells (2), n being typically between 2 and 10, said control module being carried by the operator who moves to 0 the cabin associated with the cell concerned by the change of anode, to install said control module by connecting it so that the steering assistance system is made complete in said cabin and can thus operate.

31) A steering assistance system handling and intervention operations according to any one of claims 21 to 30 wherein the system for transmitting signals between the display means and the monitors of the control module is the same as the system of transmission of commands between the control module and

The various actuators of the movable bridge, the carriage, the turret (s), the cameras, the telescopic arms and the tools. 32) A method of anode change of an electrolysis cell for the production of aluminum by igneous electrolysis, in which at least one anode determined by a new anode is replaced by using the control assistance system according to the invention. any one of claims 21 to 31,