[go: up one dir, main page]

WO2018116076A1 - Conception d'installation électrique pour installation d'électrolyse de type hall-héroult comprenant une pluralité de cellules électrolytiques connectées en série, et procédé de démarrage de ladite installation - Google Patents

Conception d'installation électrique pour installation d'électrolyse de type hall-héroult comprenant une pluralité de cellules électrolytiques connectées en série, et procédé de démarrage de ladite installation Download PDF

Info

Publication number
WO2018116076A1
WO2018116076A1 PCT/IB2017/057890 IB2017057890W WO2018116076A1 WO 2018116076 A1 WO2018116076 A1 WO 2018116076A1 IB 2017057890 W IB2017057890 W IB 2017057890W WO 2018116076 A1 WO2018116076 A1 WO 2018116076A1
Authority
WO
WIPO (PCT)
Prior art keywords
sector
cells
group
busbar
cell
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2017/057890
Other languages
English (en)
Inventor
Nadia AHLI
Sajid Hussain
Abdalla ALZAROONI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dubai Aluminium PJSC
Original Assignee
Dubai Aluminium PJSC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dubai Aluminium PJSC filed Critical Dubai Aluminium PJSC
Publication of WO2018116076A1 publication Critical patent/WO2018116076A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/16—Electric current supply devices, e.g. bus bars
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
    • C25C3/10—External supporting frames or structures

Definitions

  • the invention relates to the field of fused salt electrolysis and more precisely to the Hall- Heroult process for making aluminium by fused salt electrolysis.
  • the invention relates to a particular design of the busbar system in an electrolysis plant in which electrolytic cells are arranged side-by-side, which facilitates the start-up of the plant as well as the total or partial shut-down of the plant.
  • the Hall-Heroult process is the only continuous industrial process for producing metallic aluminium from aluminium oxide.
  • Aluminium oxide Al 2 0 3
  • molten cryolite Na 3 AIF 6
  • the resulting mixture typically at a temperature comprised between 940 °C and 970 °C acts as a liquid electrolyte in an electrolytic cell.
  • An electrolytic cell used for the Hall-Heroult process typically comprises a steel shell (so-called pot shell), a lining (comprising refractory bricks protecting said steel shell against heat, and cathode blocks usually made from graphite, anthracite or a mixture of both), and a plurality of anodes (usually made from carbon) that plunge into the liquid electrolyte contained in the volume defined by the cathode bottom and a side lining made from carbonaceous material.
  • Anodes and cathodes are connected to external busbars.
  • An electrical current is passed through the cell (typically at a voltage between 3.5 V and 5 V) which electrochemically reduces the aluminium oxide, split in the electrolyte into aluminium and oxygen ions, then into aluminium at the cathode and oxygen at the anode; said oxygen reacting with the carbon of the anode to form carbon dioxide.
  • the resulting metallic aluminium is not miscible with the liquid electrolyte, has a higher density than the liquid electrolyte and will thus accumulate as a liquid metal pad on the cathode surface below the electrolyte from where it needs to be removed from time to time, usually by suction into a crucible.
  • Industrial electrolytic cells used for the Hall-Heroult process are generally rectangular in shape and connected electrically in series, the ends of the series being connected to the positive and negative poles of an electrical rectification and control substation.
  • the general outline of these cells is known to a person skilled in the art and will not be repeated here in detail. They have a length usually comprised between 8 and 25 meters and a width usually comprised between 3 and 5 meters.
  • the cells also called “pots” are always operated in series of several tens (up to several hundreds) of pots (such a series being also called a "potline”); within each series DC currents flow from one cell to the neighbouring cell.
  • the cells are arranged in a building, with the cells arranged in rows either side-by-side, that is to say that the long side of each cell is perpendicular to the axis of the series, or end-to-end, that is to say that the long side of each cell is parallel to the axis of the series. It is customary to designate the sides for side- by-side cells (or ends for end-to end cells) of the cells by the terms "upstream” and "downstream” with reference to the orientation of current flow in the series.
  • the current enters the upstream and exits downstream of the cell: busbars collect current from the cathodic parts of a cell and feed it to the anodic part of the next downstream cell connected in series.
  • Busbars are usually made from aluminium or aluminium alloys. Being traversed by high current densities, busbars develop considerable heat under normal operation conditions due to Joule effect, and they redistribute heat through thermal conduction.
  • the electrical currents in most modern electrolytic cells using the Hall-Heroult process exceed 200 kA and can reach 400 kA, 450 kA or even more; in these potlines the pots are arranged side by side. Most newly installed pots operate at a current comprised between about 350 kA and 600 kA, and more often in the order of 400 kA to 500 kA.
  • electrolysis according to the Hall-Heroult process is a continuous process driven by the flow of electric current across the electrolyte, whereby said electric current reduces the aluminium atoms that are bounded in the alumina added to the molten electrolyte.
  • Electrolytic pots operate continuously, the consumed alumina being replenished regularly several times per day, and the spent anodes being replaced regularly and individually (typically each 25 to 35 days). Eventually, in the absence of technical problems, they need to be shut down typically each five to eight years for relining, i.e. replacement of the cathode bottom and side lining which suffer from ageing. Ageing is mainly due to wear (erosion) of the cathode surface by the moving metal pad, and due to penetration of liquid metal into the carbon materials used for the cathode bottom and the side lining.
  • a smelting plant should also be prepared for partial or even total shutdown of the plant without endangering the electrolysis cells: such a partial or total shutdown can be planned or at least foreseeable (in case of strategic capacity reduction, power shortage, raw material shortage, labour conflicts) or totally unforeseeable (in case of severe technical incidents, natural disasters and the like, see for instance V. Buzunov et al., "The quick shut down and restarting of 291 kA pre-baked potline at JSC Rusal Sayanogork from May to August 2011" , Light Metals 2013, p. 647—652).
  • Starting up a potline means energizing its busbar system.
  • Individual pots in a potline are usually started up successively or in small groups (typically several per day), as this is a critical operation requiring experienced workforce and specific supervision. Any pot that has not been started up, that requires heavy maintenance or that needs to be stopped for whatever reason has to be "taken out” (or “cut out") of the series: its needs to be bypassed. In general, bypassing a cell is necessary in two situations: during the start-up procedure of a potline, and for certain heavy maintenance operations of individual cells such as cathode replacement.
  • Figure 3b is a very simplified representation of the busbar system, and does not account for the equilibrium of the current flow, as care must be taken that cutting out a pot does not create perturbation to the equilibrium of current flow to the individual anodic risers of the downstream pot.
  • Busbar systems of typical reduction cells are described in the paper "Evolution of busbar design for aluminium reduction cells" by Kjar, Keniry and Severo, published at the 8th Australiasian Aluminium Reduction Technology Conference, 3-8 October 2004.
  • the busbar system of a reduction cell should allow the cells to be bypassed individually without the need to take the potline off load; this operation must be safe, not labour intensive and able to be deployed rapidly, and it should neither damage busbars that carry extra-current nor disturb the magneto-hydrodynamic stability of neighboring cells.
  • Bypassing is usually achieved by inserting wedges between two parallel conductors of the busbar system, thereby creating a new conductive path between them. The principle of this procedure will be explained below in relation with figure X. The insertion of such wedges allows cutting out a pot of the potline without interrupting the current flow for the downstream pots.
  • WO 2015/121 796 describes fuses that can be inserted in the air-gap between the conductors of the cathode busbar system.
  • the need to use fuses further complicates the start-up procedure of an electrolytic cell that had been shut down or cut out for whatever reason.
  • the pot goes through different stages before cut-in. For pots in a new potline, the wedges must be installed in a full section before the busbars can be energized. Then, the cathode flexes are connected, the superstructure is placed, the preheat resistor bed is prepared and anodes are installed. The pot is ready to be energized by pulling the wedges.
  • the first step is to install the wedges. Then, the superstructure is removed and the cathode flexes are disconnected. After the new pot is in place, the same steps are followed as in a new potline. For taking a pot out of the potline a plurality of wedges is needed, such as five or ten, depending on the busbar design. As a consequence, a smelting plant with three hundred pots would need to have more than a thousand wedges.
  • Wedges are also needed for testing the whole busbar, as well of individual parts thereof, system prior to its first energization.
  • Wedges are also needed when the operating production capacity of the plant is to be reduced. Indeed, it may be desirable to shut down part of the plurality of pots in a potline to avoid overproduction, or in case of shortage of raw materials or energy, or in case of severe labour conflicts, or for any other reason. According to the state of the art this can be done only by taking each single pot out of series using an appropriate number of wedges, and these wedges must then be kept in place as long as the pot is not energized. However, current will continue to flow around the inactivated pots, thereby creating ohmic losses.
  • potline design and operating procedures that allow to decrease the number of wedges and the frequency of their use at different stages of the life of a potline, from its initial construction to its terminal shut down. It would also be desirable to have a potline design that decreases ohmic losses in the vicinity of inactivated pots.
  • FIG. 4 to 9 illustrate embodiments of the invention.
  • Figure 1 schematically shows a vertical cross section of a typical Hall-Heroult electrolysis cell. It illustrates the current flow from the anode through the electrolyte to the cathode.
  • Figure 3b shows a vertical cross sections of three neighboring electrolytic Hall-Heroult cells connected in series, showing in particular the series connection of the cells that allow to feed the cathodic current of a cell into the anode frame of the neighboring downstream cell through anodic risers.
  • Figures 1 and 3a show schematic views of a Hall-Heroult cell.
  • Figure 4 schematically shows a simplified electrical diagram of a so-called “series” of pots or '"potline” according to the invention. It shows in particular the so-called Temporarily
  • TUCBs Used Crossover Busbars
  • FIGS 5 and 6 illustrate the use of these Temporarily Used Crossover Busbars.
  • Figure 7 schematically shows the shape of a Temporarily Used Crossover Busbar: figure
  • FIG 7a shows a lateral view, figure 7b a view from above.
  • Figure 8 shows a view similar to that of figures 4 to 6, in a somewhat different configuration.
  • Figure 9a and Figure 9b schematically shows a simplified electrical diagram of the four pots of a sector adjacent to a sector of a potline being energized according to the invention, with a particular emphasis on the busbars and wedges.
  • an electrolysis plant comprising a power supply and a plurality of electrolytic cells arranged along a first and a second line that are preferably parallel and straight,
  • said cells being connected in series by means of conductors, the current collected at the cathode of a cell being fed into the anode of the neighbouring downstream cell, said power supply and said plurality of electrolytic cells forming together an electric loop, in which the current can flow from said power supply successively through the cells arranged in series along said first line, through the cells arranged in series along said second line, and then back to said power supply,
  • said series of electrolytic cells is arranged in at least two successive sectors, - each sector comprises a first group of electrolytic cells arranged along said first line and a second group of electrolytic cells arranged along said second line, the current flows from said power supply successively through the cells of the first groups of cells of the first sector, then through the first group of cells of the second sector (and possibly any further sector, until the last sector), is then, when leaving the last sector, derived by one or more conductors (so-called permanently used crossover busbars) and passes then through the second group of cells of the last sector into the second group of cells of the second last sector (and possibly into the second group of cells of any further sector, until the first sector), and enters eventually, when leaving the second group of the first sector, the power supply to complete said electric loop,
  • said electrolysis plant being characterized in that it comprises between two successive sectors namely a first sector and a second sector, one or more conductors (so-called temporarily used crossover busbars) capable of creating an electrical connection between the last cell of the first group of said first sector and the first cell of the second group of said first sector.
  • conductors so-called temporarily used crossover busbars
  • said temporarily used crossover busbars are capable of reversibly creating an electrical connection between the last cell of the first group of said first sector and the first cell of the second group of said first sector.
  • the number of sector can be greater than two, namely three, four, or more than four.
  • the number of cells in each sector can be the same or different, and can be comprised between several tens and more than one hundred, and advantageously between 50 and 250.
  • said temporarily used crossover bars are capable of creating an electrical connection and of disconnecting said electrical connection in a reversible manner. This facilitates a partial or total shutdown of the plant.
  • said temporarily used crossover busbars comprise a temporarily used switch busbar that can be taken out in order to disconnect said electrical connection; when connected, said temporarily used switch busbar is advantageously bolted to the two end sections of the remaining temporarily used crossover busbar.
  • welded connectors flexible or not
  • Such an electrolysis plant according to the invention can comprise in particular three sectors, or four sectors, or even more than that.
  • Each sector typically comprises a number of cells comprised between ten and three hundred, and advantageously between 50 and 250.
  • Another object of the present invention is a process for starting up an electrolysis plant according to the invention wherein successively:
  • steps (i) to (v) are repeated for each subsequent sector adjacent to a sector that has been started.
  • the busbar system of each sector is tested for at least one of the following: electrical continuity, wedge voltage drops, earth leakage, voltage drops at cathode busbar flexibles, voltage drops across the temporarily used crossover busbars, temperatures and thermal expansions.
  • Another object of the invention is a process for at least partially shutting down an electrolysis plant according to the invention, comprising the following successive steps:
  • this process comprises a third step:
  • Still another object of the present invention is a process for producing aluminium from alumina, using an electrolysis plant according to any of the embodiments and variants of the present invention.
  • the present invention relates to the Hall-Heroult electrolysis process, which is carried out in electrolysis cells called “pots" of substantial rectangular shape.
  • the Hall-Heroult process as such, the general structure of a Hall-Heroult electrolysis pot, the way to operate the latter, as well as the cell arrangement are known to a person skilled in the art and will not be described here in more detail.
  • the terms “upper” and “lower” refer to mechanical elements in use, with respect to a horizontal ground surface.
  • conductive means “electrically conductive”.
  • the pot 1 typically comprises a potshell 2 usually made from steel, and a lining comprising a carbonaceous cathode formed from individual, parallel cathode blocks 3 and a side lining 4, said lining defining a volume for the liquid electrolyte 5 and the liquid metal pad 6 produced by the electrolysis.
  • anode busbar 16 also called “anode beam”
  • anode beam also called “anode beam”
  • anode rod 7 being connected to the carbon anode 8 by means of anode yoke 20
  • carbon anode 8 in contact with the liquid electrolyte 5 where the electrolytic reaction takes place, crosses the liquid metal pad 6 resulting from the electrolysis process and eventually will be collected at the cathode block 3.
  • cathode blocks are symmetric and have collector bar 9 ends coming out on each side, in side by side arrangements of electrolytic cells half of the current collected by the collector bars 9 of the cathode blocks 3 will flow directly to the downstream longitudinal part 10 of the cathode busbar system, while the other half flows to the upstream longitudinal part 11.
  • Flexible connectors 12 are used to connect the ends of the cathode collector bars 9 to the cathode busbar 10, 11.
  • Said collector bars 9 can be full bars, as in figure 1 , or half bars 9a, 9b, as in figure 3b.
  • Conductor 13 carries the current collected at the upstream part 11 of the cathodic busbar system to the anode risers 18 of the downstream pot.
  • a Hall-Heroult cell further comprises an alumina feeding system 14 (usually located inside the carcass of the superstructure 19) through which alumina powder is dumped from time to time into the cell volume (see arrow on figure 3b).
  • the air space above the cell is closed by a set of covers or hoods 15 that can be removed for maintenance and anode change; the anode rods 7 are adjustably fixed to the anode beam 16 using anode clamps 17 that allow to adjust the anode heights in order to keep the inter- electrode spacing constant as the anode is consumed.
  • an aluminium smelter comprises a plurality of electrolytic cells Ci, C 2 , ... , C n- i, C n , arranged the one behind the other (side by side or end to end) along two parallel lines L1 and L2, each of which comprises n/2, i.e. m cells.
  • These cells are electrically connected in series by means of conductors, which are not shown on Figure 1.
  • the number of cells in a series is typically comprised between 50 and over 500. The electrolysis current therefore passes from one cell to the next, along arrow DC.
  • the cells are arranged transversally in reference of main direction D1 or D2 (axis of the row) of the line L1 or L2.
  • main dimension, or length, of each cell is substantially orthogonal to the main direction of a respective line, i.e. the circulation direction of current.
  • Figure 2 depicts a typical "clockwise” current orientation; the present invention applies also to counter-clockwise arrangements.
  • This arrangement of n cells connected in series along two parallel lines is called a "series" of pots or "potline”.
  • the cells depicted on figure 2 are arranged side-by- side; end-to-end arrangements are generally not used in newly built plant, but the present invention could be applied to end-to-end arrangements, too.
  • anode risers 18 are provided to carry the current collected at the downstream part 10 and at the upstream part 1 1 of the cathode busbar system of the upstream pot (noted here C n- i) to the anode beam 16 of the neighbouring downstream cell (noted here C n ).
  • Figure 4 schematically shows a simplified electrical diagram of a so-called "series" of pots or '"potline” according to the invention.
  • the electrolytic cells are arranged side-by-side in two parallel lines L1 , L2.
  • the cells are denoted by the letter C, as in figure 2.
  • they are grouped into at least two sectors S, as will be explained below.
  • Fiqure 4 shows four such sectors Si, SII, Sin, Siv- Each sector can comprise an equal number or a different number of pots.
  • the grouping into sectors is according to the order of the pots in the potline: the first sector Si is formed by the first C
  • This current flows through the conductors of pots C
  • the current crosses a pot by entering from the anode busbar (anode beam), to which it is fed, through the anode rod 7 (shown on figure 1) into the anode 8, crosses the molten electrolyte 5, where alumina is reduced into aluminium and oxygen, crosses the underlying molten aluminium pad 6 and enters into the cathode 3 where it is collected by the cathode collector bar 9 and carried to the cathode busbar system 10,11. From there it is fed into the anode risers of the neighbouring downstream cell (not shown in figure 1).
  • the conductors through which the current is fed from the cathode busbar of the upstream pot into the anode busbar of the downstream pot are referenced in figure 4 with the reference numbers 100 to 108, 110 to 118, 120 to 128, 130 to 138, 140 to 148, 150 to 158, and 160 to 168. They comprise so- called anodic risers 18 (shown on figure 3). In the example of figure 4 four such conductors are schematically represented; their number is of no importance in relation with the present invention.
  • the current is collected by a busbar system called here "Permanently Used Crossover Busbar" PUCB 164.
  • the PUCB 164 conducts the current back to the second potroom D2 where it enters the last sector through the first pot Civ,n-i. Then the current flows from the cathode busbars of pot C
  • each sector (except the last one) is defined by the presence of at least one downstream busbar system called here "Temporarily Used Crossover Busbars" TUCB.
  • TUCB Temporarily Used Crossover Busbars
  • said connection achieved by said Temporarily Used Crossover Busbars is a reversible connection
  • said Temporarily Used Crossover Busbars include appropriate means that allow either to close the circuit (thereby forming said low resistance path between the current output of the first half of cells of a sector and the current input of the second half of cells of said sector) or to open the circuit.
  • closing the TUCB allow to separate adjacent sectors.
  • said TUCB allow to separate the first sector from the second sector, and (if present) the second sector from the third sector and so on.
  • each sector comprises at least 20, preferably at least 30 pots; it can comprise more than 100 pots.
  • Figure 5 shows the same simplified electrical diagram as figure 4, but according to a specific embodiment of the invention the first Temporarily Used Crossover Busbars TUCBi are used here to separate the second sector S M from the first sector S
  • the Temporarily Used Crossover Busbars TUCBi are used to create a shunt between the conductors 110-113 that connect the last cell C
  • conductor 200 creates a shunt between conductors 110 and 115
  • conductor 201 creates a shunt between conductors 111 and 116
  • conductor 202 creates a shunt between conductors 112 and 117
  • conductor 203 creates a shunt between conductors 113 and 118. It is well within the scope of the invention to apply this principle to any number of conductors within group 110-113, group 115-118 and group 200-203, the number of conductors within each of these three groups being preferably the same.
  • Separating the second sector S M from the first sector Si has the consequence that the first sector Si remains connected to the rectifier substation RS and can operate normally, whereas the second sector S M and any subsequent sectors (in the example of figure 4 these are the third sector S m and the fourth sector S
  • wedges 21 only need to short-circuit pots located in sectors connected to the rectifier substation, inside the loop of current flowing from the rectifier substation RS to the energized TUCB and back to the rectifier substation RS.
  • the wedges 21 of pots included in the new loop of current must be inserted. Then the wedges are removed gradually when starting up each pot; these start-up procedures of individual pots are well known to a person skilled in the art and will not be described here.
  • FIG. 6 shows the same simplified electrical diagram as figure 5, but according to another specific embodiment of the invention the second Temporarily Used Crossover Busbars TUCB M are used here to separate the second sector S M from the third sector Sm.
  • the Temporarily Used Crossover Busbars TUCB M are used to create a shunt between the conductors 130-133 that connect the last cell C M , 2 of the first half of cells of the second sector S M to the first cell C
  • Conductor 210 creates a shunt between conductors 130 and 135, and conductor 211 creates a shunt between conductors 131 and 136, and conductor 212 creates a shunt between conductors 132 and 137, and conductor 213 creates a shunt between conductors 133 and 138. It is well within the scope of the invention to apply this principle to any number of conductors within group 110-118, group 130-138 and group 150-158, the number of conductors within each of these three groups being preferably the same.
  • Separating the third sector S m from the second sector S M has the consequence that the first sector Si and the second sector S M remain connected to the rectifier substation RS and can operate normally, whereas the third sector Sm and any subsequent sectors (in the example of figure 4 this is the fourth sector S
  • the same result could be obtained by cutting out each individual cell of each of the third and any subsequent sector using wedges; this implies the use of a large number of wedges that need to be inserted manually by a specifically qualified workforce.
  • the plant design according to the invention makes it possible to cut-out one or more sections of pots, starting at the last section, i.e. the one next to the PUCB.
  • This may serve several different purposes: to temporarily decrease the capacity of the plant (most frequently for commercial reasons or in case of power shortage or raw material shortage or labour conflicts) by cutting out one or more section, to allow maintenance or refurbishment of the cells or their busbar system in the cut-out section(s), or to shut down the whole plant (for instance prior to its demolition) section by section while continuing to produce metal in the sections that are still connected.
  • the plant design according to the invention makes it possible to start a plant section by section, the section next to the rectifier substation RS being started first, then the second section and so on. This is a particularly interesting use of the present invention, as it allows to start the use of the first sector(s) while the subsequent ones are being built or completed.
  • said temporarily used crossover busbars TUCB are capable of reversibly creating an electrical connection between the last cell of the first group G1 of a sector and the first cell of the second group G2 of said sector.
  • Said reversibility can be achieved by providing bolted temporarily used switch busbars 22 that close the gap between a first branch of the TUCB extending from line L1 towards line L2, and a second branch extending from line L2 towards line LlThis is shown schematically on figure 7a.
  • Welded strips 25a and 25b or flexibles can be used in addition to bolts.
  • the depicted TUCB is arbitrarily labelled 200, knowing that all TUCBSs 200,201 ,202,203 should be identical).
  • the contact zones 23 between the switch busbar 22 and the TUCB should be specifically prepared, by polishing for instance, in order to minimize contact resistances.
  • the gap G bridged by the temporarily used switch busbar 22 should not be too small for safety reasons, and when disconnected the ends 24a and 24b of the opened TUCB remaining in place should be protected by an appropriate insulating cover (such as a cover made from wood panels) in order to avoid any accidental bridging of the gap G by tools, workpieces or vehicles. If the temporarily used switch bars 22 are too long they will be too heavy for easy handling.
  • the temporarily used switch busbar 22 can be stored on a trolley of appropriate height in order to facilitate its installation and uninstallation. It is advantageous to decrease the current when removing the strips 25a and 25b between busbar 22 and 24a and 22 and 24b which were welded to improve the contacts between these busbars.
  • the potline current must be temporarily taken off in order to disconnect and uninstall the temporarily used switch busbar 22 from 24a and 24b. The same method must be applied when installing this temporarily used switch busbar 22.
  • the permanently used crossover busbars PUCB are of similar construction as the temporarily used crossover busbars TUCB.
  • of sector Si is bypassed by inserting wedges; this is known as such.
  • the TUCBi between sector Si and sector S M are connected.
  • conductor 200 creates a shunt between conductors 110 and 115
  • conductor 201 creates a shunt between conductors 111 and 116
  • conductor 202 creates a shunt between conductors 112 and 117
  • conductor 203 creates a shunt between conductors 113 and 118. This is the situation shown on figure 5. At this stage no current is flowing in the potline circuit.
  • the potline current is fed to the potline circuit of sector Si and the pots C
  • sector S M and subsequent sectors can still be under construction.
  • the process can go on with step four.
  • each pot C M of sector S M is bypassed by inserting wedges.
  • These wedges can be those previously used for the pots of sector Si. This is one of the advantages of the invention: it greatly reduces the total number of wedges that are necessary for the plant.
  • the TUCB M between sector S M and sector S m are connected.
  • conductor 210 creates a shunt between conductors 130 and 135, and conductor 211 creates a shunt between conductors 131 and 136, and conductor 212 creates a shunt between conductors 132 and 137, and conductor 213 creates a shunt between conductors 133 and 138.
  • the TUCBII can be a PUCB ; the present invention requires at least two sectors of pots.
  • a seventh step the pots C M of sector S M are started, usually one after the other, which requires to withdraw the wedges.
  • sector Sm and subsequent sectors can still be under construction.
  • the process can go on with step eight.
  • each pot C m of sector Sm is bypassed by inserting wedges.
  • the TUCB m between sector S m and sector S !V are connected.
  • conductor 220 creates a shunt between conductors 150 and 155
  • conductor 221 creates a shunt between conductors 151 and 156
  • conductor 222 creates a shunt between conductors 152 and 157
  • conductor 223 creates a shunt between conductors 153 and 158. If there is no sector S
  • a third step all the pots Cm of sector Sm are shut down one after the other, and each pot is bypassed by inserting wedges.
  • a fourth step the TUCB M between sector S M and sector Sm are connected, as described above in relation with the start-up procedure.
  • a sixth step all the pots C
  • the potline can be disconnected from the rectifier station RS, or the rectifier station RS can be shut down.
  • this method can be adapted to shut down only the last sector (in the present example S
  • Another use of the invention is related to testing of the electrical conductor system of a plant prior to its start-up, or to testing of the electrical conductor system of an added sector prior to its start-up).
  • the busbar system allows to subdivide the potline into sections that can be tested separately prior to starting up the potline.
  • a procedure for testing a potline will be presented below. The procedure is carried out sector by sector, i.e. for a plant with four sectors as in figures 4 to 6, successively on sectors Si, S M , S m , and S
  • the circuit is a sector as defined above.
  • Figure 9a schematically shows the first four pots of the first half of sector SII in potroom L1 in a configuration for testing sector S
  • Figure 9b schematically shows the last four pots of the second half of sector S M in potroom L2 in a configuration for testing sector Si.
  • the direction D1 and D2 of the current flow is indicated by an horizontal arrow in Figures 9a and 9b.
  • First sector Si will be energized.
  • Each of the n cells of sector Si is short-circuited using wedges 21.
  • the cells of sector S N can be short-circuited using wedges, except at least the first cell C M ,i of the first half of cells of sector S M and the last cell C M , n of the second half of cells of sector S M that are adjacent to the TUCBi; this will be explained below.
  • eight wedges 21 are used for each short-circuited cell; this number can be different for different types of cells.
  • the busbar configuration of figures 9a and 9b correspond to that of figure 5, except for two essential features: the cells of sector Si are short-circuited by wedges 21 , and in the busbar system of the first cell C M ,i of the first half of cells of sector SM that is adjacent to the TUCBi and in the busbar system of the last cell C M , N of the second half of cells of sector S M that is also adjacent to the TUCBi, the (positive) anode risers are disconnected from the cathode busbars of their adjacent upstream cell: the anode risers are physically interrupted, having downstream parts 18b (welded to the anode beam 16) that are disconnected from the respective upstream parts 18a (connected to the cathode busbar of the upstream adjacent cell).
  • the TUCBs 200,201 ,202,203 connecting the first half of pots of sector Si to the second half of pots of sector Si are installed, that is to say: connected, so that the sector Si (not shown on figures 9a and 9b) to be energized is totally separated (electrically insulated) the from next sector S M .
  • the busbar structure prior to testing a sector of the potline, four conditions must be fulfilled regarding the busbar structure:
  • At least the first pot (and preferably the two first pots, and still more preferably the three first pots) of the first half of pots of the next sector, and at least the last pot (and preferably the two last pots, and still more preferably the three last pots) of the second half of pots of the next sector, must have all anode riser disconnected from the upstream cathode busbar system, and
  • At least the first pot (and preferably the two first pots, and still more preferably the three first pots) of the first half of pots of the next sector, and the last pot (and preferably the two last pots, and still more preferably the three last pots) of the second half of the next sector must have no wedges, and
  • the tests are carried out in as many stages as there are sectors, each stage comprising one or more steps.
  • first stage discrete steps of increasing amperage are applied to the first sector Si (i.e. the sector adjacent to the rectifier substation RS).
  • a first step is about 50 kA
  • a second step is about 100 kA
  • a third step is of about 200 kA
  • a fourth step is about 450 kA
  • the fourth step should be chosen in accordance with the maximum amperage: the values given here as examples are adequate for a maximum amperage of about 460 kA to 500 kA, knowing that it is advantageous to carry out testing at a current somewhat higher than the nominal operating current.
  • the first step comprises at least visual inspection (presence of sparking or arcing, preferably from the potroom floor and the basement) and pot voltage measurement.
  • the second step comprises electrical measurements that are preferably carried out from the potroom floor and from the basement; these measurements include one or more of the following:
  • thermal and mechanical measurements as well as visual inspection are carried out when the busbars have reached thermal equilibrium. These thermal and mechanical measurements (whereby the thermal measurement typically use contacts probes and/or infrared probes, as appropriate) and inspections comprise one or more of the following:
  • busbar thermal expansion by measuring the thermal displacement from previously marked areas at the busbar supports
  • Tests at the third step and further steps comprise the same tests as in the first step.
  • Stage 2 and the following stages are different from stage 1 but all similar: the risk is reduced by having first the two TUCBs (or at the last stage the last TUCB and the PUCB) in parallel circuit before removal of the first TUCB.
  • a first step during stage 2 short circuit test the continuity of the busbar electrical circuit of Sector S M is verified by connecting TUCB M , therefore energizing the Sector S M before disconnecting the TUCBi between line L1 and line L2; in this situation the current flows through the TUCBi and in parallel through Sector S M and TUCB M , allowing to detect defects in the busbars of Sector S M .
  • the voltage drops of the TUCB located between the operating sector and the tested sector as well as the voltage drops of the TUCB located after the tested sector and operating in parallel during the test is measured.
  • the voltage drop across the TUCB located between tested sector and the next sector (can be a PUCB if the tested section is the last one) (in the example: TUCB M if section S M is tested) is measured after opening (disconnecting) the TUCB located between operating sector and the tested sector (in the example: TUCBi).
  • TUCB M if section S M is tested
  • TUCBi opening (disconnecting) the TUCB located between operating sector and the tested sector
  • the second step of stage 2 comprises electrical measurements that are preferably carried out from the potroom floor and from the basement; these measurements include one or more of the following:
  • thermal and mechanical measurements as well as visual inspection are carried out when the busbars have reached thermal equilibrium.
  • thermal and mechanical measurements comprise one or more of the following:
  • busbar thermal expansion by measuring the thermal displacement from previously marked areas at the busbar supports
  • the invention allows to decrease the number of wedges to be available in the plant; this saving will be the higher the more sectors there are.
  • the invention allows to divide the number of required wedges by four.
  • the invention allows to separate the part of potline that is ready for operation from the rest of the potline that is still under construction, thereby permitting early production which is important for the profitability of the project.
  • the temporarily used crossover busbars are used during the start-up phase of the plant, but can stay in place (after disconnection) and can be used later if required for various reasons, such as any kind of emergency situation (labour conflict, serious damage to the busbar system in one or more pots, prolonged power outage, prolonged disruption in raw material supply) or any kind of strategic decision (partial shutdown of the plant to reduce its capacity for economic reasons, complete shutdown of the plant for whatever reason, restart of the plant after its partial or complete shutdown).
  • the invention allows to save energy during the start-up phase of the plant by having the current flow only through a limited number of wedged pots (that is to say: the pots belonging to the same sector), instead of having all pots of the potline wedged, knowing that the voltage drop through a wedged pot is typically of the order of 0.15 to 0.30 V, depending upon the busbar design and the amperage.
  • Another advantage of the invention is related to the internal organization of the plant: the start-up and early operation stage of a pot being highly critical for its lifetime, it may be advantageous to concentrate the experienced operation workforce in a smaller part of the potline when starting up the plant, namely in a sector separated from the plant still under construction where the construction work force is concentrated.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

Cette invention concerne une installation d'électrolyse, comprenant une alimentation électrique (RS) et une pluralité de cellules électrolytiques (C) agencées le long d'une première et d'une seconde ligne (L1, L2), lesdites cellules étant connectées en série au moyen de conducteurs, le courant étant collecté à la cathode d'une cellule et étant introduit dans l'anode de la cellule aval avoisinante, ladite alimentation électrique (RS) et ladite pluralité de cellules électrolytiques formant ensemble une boucle électrolytique, dans laquelle le courant peut circuler en provenance de ladite alimentation électrique (RS) successivement à travers les cellules agencées en série le long de ladite première ligne (L1), à travers les cellules agencées en série le long de ladite seconde ligne (L2) puis en retour vers ladite alimentation électrique (RS). Ladite série de cellules électrolytiques (C) est agencée en au moins deux secteurs successifs (SI, SII). Chaque secteur (S) comprend un premier groupe (G1) de cellules électrolytiques agencées le long de ladite première ligne (L1) et un second groupe (G2) de cellules électrolytiques agencées le long de ladite seconde ligne (L2). Le courant circule de ladite alimentation électrique (RS) successivement à travers les cellules du premier groupe (G1(SI)) de cellules du premier secteur (SI), puis à travers le premier groupe (G1(SII) de cellules du second secteur (SN) (et éventuellement tout secteur supplémentaire, jusqu'au dernier secteur), puis, lorsqu'il quitte le dernier secteur, il est dérivé par un ou plusieurs conducteurs (de type barres omnibus de croisement utilisées en permanence (PUCB)) et traverse le second groupe de cellules du dernier secteur pour s'introduire dans le second groupe de cellules de l'avant-dernier secteur (et éventuellement, dans le second groupe de cellules de n'importe quel secteur supplémentaire, jusqu'au premier secteur), et il pénètre éventuellement, lorsqu'il quitte le second groupe (G2(SI) du premier secteur (Si), dans l'alimentation électrique (RS) pour compléter ladite boucle électrique. Ladite installation d'électrolyse est caractérisée en ce qu'elle comprend entre deux secteurs successifs (SI, SII) un ou plusieurs conducteurs (de type barres omnibus de croisement utilisées temporairement (TUCB)), capables de créer une connexion électrique entre la dernière cellule du premier groupe (G1(SI)) de cellules dudit secteur (Si) le long de L1 et la première cellule du second groupe (G2(SI)) de cellules dudit secteur (Si) le long de L2.
PCT/IB2017/057890 2016-12-21 2017-12-13 Conception d'installation électrique pour installation d'électrolyse de type hall-héroult comprenant une pluralité de cellules électrolytiques connectées en série, et procédé de démarrage de ladite installation Ceased WO2018116076A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1621787.9A GB2557972A (en) 2016-12-21 2016-12-21 Electrical design for a Hall-Héroult electrolysis plant comprising a plurality of electrolytic cells connected in series, and method to start-up said plant
GB1621787.9 2016-12-21

Publications (1)

Publication Number Publication Date
WO2018116076A1 true WO2018116076A1 (fr) 2018-06-28

Family

ID=58284355

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2017/057890 Ceased WO2018116076A1 (fr) 2016-12-21 2017-12-13 Conception d'installation électrique pour installation d'électrolyse de type hall-héroult comprenant une pluralité de cellules électrolytiques connectées en série, et procédé de démarrage de ladite installation

Country Status (2)

Country Link
GB (1) GB2557972A (fr)
WO (1) WO2018116076A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220341048A1 (en) * 2019-09-17 2022-10-27 Amc Supply circuit for electrolytic cell comprising a short-circuit device and a disconnector

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3155243A1 (fr) * 2023-11-13 2025-05-16 Aluminium Dunkerque Procede de reparation de barre conductrice

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1046705A (en) * 1964-05-27 1966-10-26 British Aluminium Co Ltd Improvements in or relating to the operation of electrolytic reduction cells for theproduction of aluminium
RU2060304C1 (ru) * 1988-05-11 1996-05-20 Норск Хюдро А.С. Устройство компенсации
RU2164557C2 (ru) * 1999-04-20 2001-03-27 ОАО "Объединенная компания "Сибирский алюминий" Ошиновка электролизера для получения алюминия
US20070256930A1 (en) * 2004-09-23 2007-11-08 Linnerud Glenn O Method for Electrical Connection and Magnetic Compensation of Aluminium Reduction Cells, and a System for Same

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3617454A (en) * 1969-11-12 1971-11-02 Arthur F Johnson Bus structure from aluminum reduction cells
JPS6054399B2 (ja) * 1982-04-30 1985-11-29 住友アルミニウム製錬株式会社 アルミニウム製造用電解炉

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1046705A (en) * 1964-05-27 1966-10-26 British Aluminium Co Ltd Improvements in or relating to the operation of electrolytic reduction cells for theproduction of aluminium
RU2060304C1 (ru) * 1988-05-11 1996-05-20 Норск Хюдро А.С. Устройство компенсации
RU2164557C2 (ru) * 1999-04-20 2001-03-27 ОАО "Объединенная компания "Сибирский алюминий" Ошиновка электролизера для получения алюминия
US20070256930A1 (en) * 2004-09-23 2007-11-08 Linnerud Glenn O Method for Electrical Connection and Magnetic Compensation of Aluminium Reduction Cells, and a System for Same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220341048A1 (en) * 2019-09-17 2022-10-27 Amc Supply circuit for electrolytic cell comprising a short-circuit device and a disconnector
US12168832B2 (en) * 2019-09-17 2024-12-17 Amc Supply circuit for electrolytic cell comprising a short-circuit device and a disconnector

Also Published As

Publication number Publication date
GB201621787D0 (en) 2017-02-01
GB2557972A (en) 2018-07-04

Similar Documents

Publication Publication Date Title
US5286353A (en) Electrolysis cell and method for the extraction of aluminum
AU2009207872B2 (en) Device and method for short-circuiting one or more cells in an arrangement of electrolysis cells intended for the production of aluminium
WO2018116076A1 (fr) Conception d'installation électrique pour installation d'électrolyse de type hall-héroult comprenant une pluralité de cellules électrolytiques connectées en série, et procédé de démarrage de ladite installation
CN101155947B (zh) 阳极支承装置
WO2017163162A1 (fr) Connecteur électrique souple destiné à une cellule électrolytique
US3317413A (en) Control of alumina content during igneous electrolysis
WO2019012376A1 (fr) Cellule d'électrolyse pour procédé hall-héroult, avec des tuyaux de refroidissement pour refroidissement d'air forcé
EP0610373A1 (fr) Element d'anode precuite continue
RU2118409C1 (ru) Способ замены ошиновки алюминиевых электролизеров действующей электролизной серии
CN114921815B (zh) 一种不停槽更换镁电解槽阳极的方法
WO2017158501A1 (fr) Dispositif de maintien d'ensembles d'anode pendant le préchauffage électrique de cellules hall-héroult, et procédé de préchauffage de cellules hall-héroult utilisant un tel dispositif
WO2021061015A1 (fr) Procédé de calcination de sole d'électrolyseur d'aluminium
GB2542555A (en) Removable cover and flap for easy access to the intercalary space in a series of electrolytic Hall-Héroult cells
CA3052237C (fr) Amenagement modulaire de bus pour series de cellules d'electrolys d'aluminium
WO2018234946A1 (fr) Installation d'électrolyse utilisant le procédé hall-héroult, à compensation du champ magnétique vertical
GB2548830A (en) Cathode block with copper-aluminium insert for electrolytic cell suitable for the Hall-Héroult process
GB2525156A (en) Start-up fuse for aluminium reduction electrolysis cell
AU2008233392B2 (en) Improvements relating to electrolysis cells connected in series and a method for operation of same
US3391074A (en) Apparatus for detection of alumina content of aluminum electrolysis cells
GB2542360A (en) Hinged grating for easy access to the outer shell of electrolytic cells suitable for the hall-héroult process
WO2019162817A1 (fr) Cellule électrolytique dotée d'une superstructure ayant des pattes intermédiaires, appropriée pour le procédé hall-héroult
WO2017163154A1 (fr) Système de barre omnibus permettant de compenser le champ magnétique dans des rangées adjacentes de cellules électrolytiques placées transversalement
Tabereaux et al. In-situ formation of slots in Søderberg anodes
SU1062312A1 (ru) Способ монтажа подовой секции алюминиевого электролизера
WO2019193451A1 (fr) Caisson de cuve pour cellule électrolytique destiné à être utilisé avec le procédé hall-héroult

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17882746

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17882746

Country of ref document: EP

Kind code of ref document: A1