NO20181483A1

NO20181483A1 - A method and equipment for storing and transporting hot gas emitting components

Info

Publication number: NO20181483A1
Application number: NO20181483A
Authority: NO
Inventors: Morten Karlsen; Are Dyrøy; Tore Øren; Albert Berveling
Original assignee: Norsk Hydro As
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2020-05-21
Also published as: AU2019382674B2; EP3884082A1; WO2020104119A1; BR112021007370A2; EA202191405A1; NZ774532A; ZA202102663B; CA3115400A1; AU2019382674A1

Description

A method and equipment for storing and transporting hot gas emitting compone

The present invention concerns a method and equipment for storing and transporti gas emitting components such as anode butts from a pre-baked electrolysis cell syst The equipment comprises as a main component a closable, transportable stor container. In addition to the hot consumed anodes (anode butts), other emissive ma such as anode cover material and bath material have to be removed from cell operation, in particular during anode change or other maintenance operation invention also includes use of the equipment for transportation of new anodes to th

In connection with the operation of a modern electrolysis system for the productio aluminium, there are extensive requirements for the transportation of various materi the cells, for example oxide, fluoride, anodes, etc. Moreover, operation involves removal of consumed anodes, crusts and other material from the cells in addition t metal produced.

Some of this transportation is crane-based, i.e. the objects are handled by means o or more cranes that can serve the cells in the electrolysis hall in connection with spe operations. Another part of the transportation is performed by means of wheeled ve In particular, closed boxes for anode butt transport is commonly transported by mea wheeled vehicles. The vehicles can be driven by an operator or automatic guided ve has also been proposed.

One problem with electrolysis cell systems that are built so that the cells are arrange two parallel rows with a row of supporting columns in the space between the rows is it can be difficult to manoeuvre the vehicles in an effective manner in the system. Wh for example, consumed anodes and other material are removed from an electrolysis it is important that it can be transported fast either out of the hall or to a temporary s so that the hall atmosphere is not impaired on account of unnecessary delay in rem the stated anodes or material, which will emit gases after removal from the cell. If temporary store is used, it is important that this is arranged so that the operation of rest of the electrolysis cell system is affected as little as possible, while the distance ov which hot material is transported is limited to a minimum.

DE 4344036A1 shows a method and an arrangement for changing anodes in conn with aluminium melting electrolysis with heat recovery. The arrangement compris transport containers that are designed to hold consumed anodes and bath materi transport containers in which consumed anodes/bath material are placed are trans to a chamber in a heat exchanger system. The residual heat from the material in the st containers is utilised to preheat new anodes. A filter device is arranged for preve fluoride gas to escape from the container.

DE 4221882 A1 concerns a transport device for hot residual anodes. The transport d comprises a closed container in which consumed anodes are inserted. To limit emissi of contaminated gases such as fluoride into the hall atmosphere during transportati of the hall, the container is fitted with a filter that can be made of alumina to chemi bind fluoride in the gas in order to retain such gases. The container comprises swiv lids to allow anodes to be inserted/removed.

EP 0838540 shows a temporary store for used anodes and bath material that consist a container that is connected to an opening in the superstructure of an electrolysis

US 6,161,307 discloses a fluid bed system for cooling hot spent anode butts. The b are brought to an elongated fluidised bed cooling chamber comprising particles of a and conveyor means for transporting a hot, spent anode butt through the fluidise Since the hot anode buttes emerging from the potlines are at that point emitting flu at a very rapid rate, it is important to bring them to the fluidised bed as soon as pos and the hot anode butts may be transported in a closed mobile carrier, that is typic self-contained, free-standing, moveable box. It is adapted to reducing the contact b the hot anode butt and moist atmospheric air before the butt has cooled sufficie avoid the generation of HF, and fluoride emissions during the transportation ma further minimized by covering the hot butts with alumina. The hot anode butts have a of solidified bath which is attached to the top of each butt.

EP2507413B1 discloses a process for changing used anode and a support and sy for temporarily storing such a used anode where the butt having pieces of bath cove it, is placed on a support and a smothering powder such as alumina is poured ont spent anode to limit the fluorinated gas emission. The support can be associ functionally with a tank that is pre-filled with powder and that is opened when a s anode is on the support such that the powder flows towards the spent anode by forces. In one other embodiment, the powder can be poured onto the spent an means of a commonly available overhead travelling crane equipped with a po discharge conduit to cover the anode with powder. Such equipment is commonly us covering new anodes replacing a spent one in a cell.

EP2710170B1 discloses a method and device for processing anode butts by coveri said butts with alumina being able to adsorb fluoride, where the butt is immersed alumina that is fluidised to facilitate immersion so that the butt is covered by static alum until the end of its transport to a anode butt station for further processing of the butt device comprises a tray containing non-fluidised alumina in sufficient quantities to c the anode butt and means of fluidisation of this alumina. The bottom of the tray c made of a material able to retain alumina above it while forming a plenum chamb fluidised gas below it and having sufficient porosity to fulfil the function of a fluidis fabric.

Applicant’s own W003/042618 discloses a method and an arrangement for the operat of an electrolysis cell system, comprising a hall with electrolysis cells that use anodes the pre-bake type for the production of aluminium, comprising temporary storag consumed anodes and other material that are removed from the cells in closable st arrangements arranged in the hall, where the storage arrangements are connecte extraction system, the storage arrangements are arranged at a distance from the cel that the operations performed on the cells are not obstructed by the stor arrangements, and the storage arrangements are also designed to be connecte extraction system placed at a distance from the cells.

One challenge with this solution is to avoid air-burn of the carbon based material i butts, due to the surrounding air being sucked into the storage arrangement. Air b unwanted as it involves loss of recyclable material and prolongation of the cooling due to the combustion taking place.

This may be remedied at least partly by covering said butts by pouring alumina po onto it and to limit the contact between the butts and oxygen containing gas. Howev be able to apply the alumina powder at least one or more lids have to be open there is a high risk of first puncturing the underpressurized system inside the stor arrangement and secondly that at least some of the alumina powder which may co some air due to previous fluidisation, will be expanding as it hits the hot butts and t gas containing both alumina powder and fluoride may leak out of the storage arran during this operation and end up in the ambient air.

This can be avoided by the present method and equipment where alumina or s fluoride adsorbing material is brought to cover the anode butts and other hot, gas e components while the container itself is closed, i.e. with the lids or similar closure mea shut. In an embodiment, the container may be connected to a suction system an underpressurized at least during this operation. It can either be connected to a ce be underpressurised by the cell’s gas extraction system, or to a separate gas extrac system. Still further, the equipment comprises a system for distribution of the fluori adsorbing material inside the container that allows the material to flow in a gentle m and to cover the hot emissive components without heavy dusting.

These and further advantages can be achieved with the invention as defined accompanying claims.

The present invention will be described in further detail in the following by mea examples and figures, where:

Figure 1 shows in perspective an equipment according to the present inventi where the lids of a container are in open position and with two ano therein,

Figure 2 shows in perspective an equipment according to the present inventi where the lids of a container are shut and with two anodes therein,

Figure 3 shows in top view an equipment with the lids shut, and an indication of t cross-sectional views A-A and B-B in Fig. 4 and 5 respectively,

Figure 4 shows a cross-sectional view of the equipment along line A-A in Fig. 3, a with no anodes therein

Figure 5 shows a cross-sectional view of the equipment along line B-B in Fig. 3, a with no anodes therein,

Figure 6 shows a cross sectional view of the equipment along line B-B in Fig. 3, a with two anode butts therein,

Figure 7 shows an enlarged portion of the encircled area in Fig. 6,

Figure 8 shows the principles of operating the fluidising elements of Fig. 7,

Figure 9 shows the principles of operating the fluidising elements of Fig. 7.

In Figure 1 there is disclosed in perspective an equipment 1 according to the pr invention, where lids 3, 4 of a container 2 are in open position and with two partly s anodes stored therein. The rods 5, 6 of the anodes are supported by a frame struct having brackets 8, 9.

In Figure 2, the equipment is rotated 90 degrees anti-clockwise and the lids 3, 4 are s

Figure 3 shows in top view the equipment 1 where the frame 7 has been removed with the lids 3, 4 shut, and an indication of the cross-sectional views A-A and B-B sho in Fig. 4 and 5 respectively. It can be seen closable openings 10, 11, 12 communicat with compartments surrounding the container for filling fluoride adsorbing powder su alumina into the container 2, which shall be explained later. Further, the lids have 13, 14 that can be soft lip seals that close accurately the opening between a slot i lids and the anode rods 5, 6.

Figure 4 shows a cross-sectional view through the equipment 1 along line A-A disclosed in Fig. 3, where there are compartments 23, 24 for receiving and storin fluoride adsorbing powder, such as alumina, that can be filled via the closable op 10, 11, 12. See also Fig. 3 where two additional compartments are indicated at posit 27 and 28. In the receiving compartments 23, 24 there are further arranged flui elements 25, 26 for fluidising the material during the filling operation, to be abl distribute the material to all available spaces in the compartments. Compartments 23’, are not filled during this filling operation, just partly due to the material’s angle of re During the operation of covering the butts with powder, materials can be transporte and from these compartments 23’, 24’ and into the chamber C of the container via o more openings O in the walls of the container 2 by activating fluidising elements 25” , together with the elements 25, 26 and 25’, 26’ (see also Fig. 7).

The equipment 1 can be provided with tanks for pressurized fluidising gas 15, 16.

16 is for the purpose of explanation not cross-sectioned and reference 17 is a coupli filling pressurised gas accessible from the outside of the container. In case pressuri air is accessible at the loading/unloading point, it is not necessary to provide equipment with tanks for pressurised gas, just a gas filling joint will be sufficient.

Similarly, Figure 5 shows a cross-sectional view through the equipment 1 along line as disclosed in Fig. 3, where the compartments 27, 28 for receiving and storing a flu adsorbing powder such as alumina that can be filled via at least one closable openi 11,12. In the receiving compartments 27, 28 there are further arranged fluidising ele 29, 30 for fluidising the material during the filling operation, to be able to distribute material to all available space in the compartments. Compartments 27’, 28’ are not fi during this filling operation. Materials can be transported via and from these compart 27’, 28’ and into the chamber C via openings O’ in the walls of the container 2 by activ fluidising elements 29’, 30’ similar to that explained in Fig. 4 and 7. Tanks 18, 19 wit pressurised fluidising gas are provided in the equipment outside the container wall gas can be controlled by one or more valves and transported via pipes 18’ to the flui elements. The release of gas can be done manually or controlled by a PLC. A se registering the presence of a butt and possibly the closure of the lids can be used to c the activation of fluidising gas and filling of powder into the chamber C.

Figure 6 shows a cross sectional view of the equipment 1 along line B-B in Fig. 3, with two anodes therein, having anode rods 5, 6, anode yokes 5’, 6’ and anode c blocks 5” , 6” . The anodes are supported by the frame 7, and further main compone the equipment 1 such as container 2, compartments 23, 23’; 24,24’, tank 15, couplin central chamber C are shown.

Figure 7 shows an enlarged portion of the encircled area in Fig. 6 and there are compartment 23 for receiving and storing a fluoride adsorbing powder such as al that can be filled via the closable openings. In the receiving compartment 23 th further arranged fluidising element 25 for fluidising the material during the filling oper to be able to distribute the material to all available spaces in the compartme Compartment 23’ is not filled during this filling operation, i.e. the dividing wall D will se as a lock similar to a water lock Materials can be transported via and from compartm 23’ and into the chamber C via opening O in the wall of the container 2 by activ fluidising elements 25, 25’ together with the fluidising element 25” . Piping 18” and 15 is also shown, as well as anode rod 5, anode yoke 6’ and anode carbon block part.

Fig 8 and 9 shows one embodiment of operating the fluidising elements of Fig. 7, w Fig. 8 relates to filling material in the compartment 23 of the box during activating fluidising element 25 and 25’ to enhance distribution of material M to the vari compartments. The piping 18” and supply of air is arranged so that the fluidising ele 25’ and 25” can be operated separately.

In Fig. 9 the material content of the compartment 23 is to be directed to the cent chamber C. Materials M can be transported from compartment 23 via compartment and into the chamber C via opening O in the wall of the container 2 by activating flui elements 25, 25’ and 25” simultaneously.

The opening O must be arranged at a level that secures complete covering of the b the chamber C. To obtain this, the angle of repose of the material must be account as well as varying heights of the butts and also varying presence of anode cov material ACM at the top of the butts.

The method relates to storing and transporting hot gas emitting components fro electrolysis cell for aluminium production, the cell being of Hall-Héroult type with preba anodes, the components comprise at least one of;

spent anode/s, bath material, anode covering material. In addition, new anodes c transported in the equipment. However, these need not to be covered by an ads material.

According to the method, component/s are removed from the electrolysis cell and pl in a central chamber ( C ) of a top open closeable container provided with lid/s that be the closed immediately after placing the component/s in the container to limit emissions to ambient air. Then said component/s are covered with a layer of a fluo absorbing material that can be alumina. The lid/s can be shut automatically or man and to operate the equipment, a PLC can be integrated in the equipment an remotely controlled by manual trigging of actions.

The fluoride adsorbing material can be poured into the central chamber of the co by at least one feeding hole arranged in the top of the container where the feedin closed after the filling operation.

Alternatively, the container is provided with compartments at its outside, sai compartments having onboard air slides for distribution of the fluoride adsorbing m into the central chamber ( C ) where the hot gas emitting component/s is placed., transport is carried out by fluidising the material, which then flows by gravity into t chamber( C ) through one or more openings O in the wall/s of the container 2. The flu adsorbing material is readily available for said air slides as pre-stored material compartments of the equipment or readily available by external filling during the cov operation.

The fluoride adsorbing material can be alumina that is branched off the ordinary al transport to the cells and discharged by a filling hose or the similar, or can be alu carried in a reservoir on a crane or a vehicle, said reservoir having a discharge hos During filling of fluoride adsorbing material, the central chamber ( C ) of the containe be subjected to an underpressure by means of a gas extraction system, that could b gas extraction system of a cell where the central chamber is connected to this system one hose or the like.

Generally, the equipment comprises a top open closeable container that is closea means of lid/s, and further comprising means for allowing a fluoride adsorbing mater be poured onto said component/s that have been brought into a central chamber the container. The equipment can further comprise compartments with fluidising air sli arranged at the outside of the container’s walls 2, where material is readily availabl said air slides as pre-stored material in compartment/s in the equipment or rea available by external supply of material during the covering operation. The air s distribute the fluoride adsorbing material by fluidisation of the material, through o more inlet openings (O) in the side walls of the container 2, further into the central cha (C) and finally covering said component/s with material.

The container can have air slides and corresponding inlet openings arranged alo two, three or all its sides, which in a preferred embodiment is four side walls.

The compartments for pre-storing material are arranged in the equipment, along at one side of the container wall 2.

The equipment may comprise tank/s for pressurised fluidising gas, where the tank/s be pre-filled by a coupling accessible from the outside of the equipment, or it can accessible coupling/s for supplying pressurized air.

The container can be thermally insulated, by appropriate materials. The insulation c arranged at the inside or the outside of the container’s walls.

A Programmable Logic Controller can be included in the equipment for control operations such as closing the lids, pouring action of fluoride adsorbing materi controlling valves between the tanks for pressurised fluidising gas and the fluidi elements, etc.

After use, the equipment can be turned up-side down for removal of the fluoride ads material and other fragments of material.

Claims

1. A method for storing and transporting hot gas emitting components from electrolysis cell for aluminium production, the cell being of Hall-Héroult type wi prebaked anodes, the components comprise at least one of; spent anode/s, material, anode covering material, wherein the method comprises removal of s component/s from the electrolysis cell and placing it in a central chamber ( C ) o top open closeable container provided with lid/s that can be closed,

c h a r a c t e r i s e d i n t h a t

the lid/s are closed immediately after placing the component/s in the contain limit gas emissions to ambient air, followed by covering said component/s with layer of a fluoride adsorbing material that can be alumina.

2. A method in accordance with claim 1,

c h a r a c t e r i s e d i n t h a t

the lid/s can be shut automatically or manually.

3. A method in accordance with claim 1,

c h a r a c t e r i s e d i n t h a t

the fluoride adsorbing material is poured into the central chamber of the cont by at least one feeding hole arranged in the top of the container where the f hole is closed after the filling operation.

4. A method in accordance with claim 1,

c h a r a c t e r i s e d i n t h a t

the container is provided at its outside with onboard air slides for distribution of fluoride adsorbing material into the central chamber ( C ) where the hot gas emit component/s is placed, the transport is carried out by fluidising the material, wh then flows by gravity into the chamber( C ) through one or more openings in wall/s of the container.

5. A method in accordance with claim 4,

c h a r a c t e r i s e d i n t h a t

the fluoride adsorbing material is readily available for said air slides as pre-sto material in compartments of the equipment or readily available by external fill during the covering operation.

6. A method in accordance with claim 3 or 5,

c h a r a c t e r i s e d i n t h a t

the fluoride adsorbing material is alumina that is branched off the ordinary alu transport to the cells and discharge by a filling hose or the similar, or can be alu carried in a reservoir on a crane or a vehicle, said reservoir having a discha hose.

7. A method in accordance with claim 1,

c h a r a c t e r i s e d i n t h a t

the central chamber ( C ) of the container during filling of fluoride adsorbing mat is subjected to an underpressure by means of a gas extraction system.

8. A method in accordance with claim 7,

c h a r a c t e r i s e d i n t h a t

the gas extraction is performed by connecting the central chamber ( C ) of t container to the gas extraction system of an electrolysis cell via a hose or t similar.

9. An equipment for storing and transporting hot gas emitting components take of an electrolysis cell for aluminium production, the cell being of Hall-Héroult ty with prebaked anodes, the components comprise at least one of; spent ano bath material, anode covering material, the equipment comprises a top o closeable container that is closeable by means of lid/s, and further comprisi means for allowing a fluoride adsorbing material to be poured onto component/s that have been brought into a central chamber ( C ) of the conta c h a r a c t e r i s e d i n t h a t

the equipment further comprises at least one fluidising air slide/s arranged at outside of the container where material is readily available for said air slide/s pre-stored material in compartment/s in the equipment or readily available external supply of material during the covering operation, and that the air sli distribute the fluoride adsorbing material by fluidisation of the material, throug or more inlet openings (O) in a side wall/s of the container, further into the ce chamber (C) and finally covering said component/s with material.

10. An equipment in accordance with claim 9,

c h a r a c t e r i s e d i n t h a t

the container has air slides and corresponding inlet openings arranged alon than one side and up to all its sides.

11. An equipment in accordance with claim 9,

c h a r a c t e r i s e d i n t h a t

the compartment/s for pre-storing material are arranged along at least one si the container and may comprise all sides.

12. An equipment in accordance with claim 9,

c h a r a c t e r i s e d i n t h a t

the equipment comprises tank/s for pressurised fluidising gas, where the tanks be pre-filled by a coupling accessible from the outside of the equipment.

13. An equipment in accordance with claim 9

c h a r a c t e r i s e d i n t h a t

the container is thermally insulated.

14. An equipment in accordance with claim 9,

c h a r a c t e r i s e d i n t h a t

a PLC controller is included in the equipment for controlling operations such closing the lids, pouring action of fluoride adsorbing material, etc.

15. An equipment in accordance with claim 9,

c h a r a c t e r i s e d i n t h a t

the equipment comprises externally available coupling/s for supply of pressuri fluidising gas.