AU2006323329B2

AU2006323329B2 - A method and a device in connection with handling covers in a superstructure in an electrolytic cell

Info

Publication number: AU2006323329B2
Application number: AU2006323329A
Authority: AU
Inventors: Helge Kleiva; Frank Ovstetun
Original assignee: Norsk Hydro ASA
Current assignee: Norsk Hydro ASA
Priority date: 2005-12-09
Filing date: 2006-11-24
Publication date: 2010-12-16
Anticipated expiration: 2026-11-24
Also published as: IS8739A; WO2007067061A8; CN101326311B; CA2630912A1; MY143375A; RU2008127848A; CN101326311A; RU2404293C2; IS2772B; WO2007067061A1; DK200800945A; AU2006323329A1; NO20055865L; NO328467B1; ZA200804972B

Description

1 A method and a device in connection with handling covers in a superstructure in an electrolytic cell . The present invention concerns a method and a device for enclosing an electrolytic cell of the 5 Hall-H6roult type for the production of aluminium, whereby process gases developed during the electrolysis process are prevented from flowing out into the cell's ambient air and maintenance on the cell is not prevented unnecessarily. A reference herein to a patent document or other matter which is given as prior art is not to be 10 taken as an admission that that document or matter was, in Australia, known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims. Covering the superstructure of electrolytic cells of the Hall- Heroult type to collect and remove 15 process gases in a controlled manner is a prior art process. The applicant's own US patent, US 6,790,337, concerns a cell with a superstructure that can have one or more removable covers. Such covers are normally arranged in such a way that they cover the long sides of the superstructure by several covers being mounted side by side 20 on a frame structure. With the present invention, a new solution has been developed for removable covers for electrolytic cells based on the covers overlapping in order a) to achieve better enclosure and b) to make the covers easier to handle for removal and application. Such handling can be 25 performed using a crane or similar with a manipulator arm designed to change anodes or perform other operations on the electrolytic cell. The principle in accordance with the present invention may be used both for single anode changes (changing one anode) and double anode changes (changing two anodes). 30 These and other advantages may be achieved with the invention as it is defined in the attached claims. According to one aspect of the present invention, there is provided a method in connection with handling covers in a superstructure in an electrolytic cell, whereby the cell includes one 35 or more removable covers mounted side by side, the covers are removed in connection with operations on the cell and are put back into position when the operations have been la completed, wherein when the covers are removed, the total sideways extent of the covers is reduced initially by the covers being moved together sideways before they are lifted off. According to another aspect of the present invention, there is provided a device in connection 5 with covering an electrolytic cell of the Hall-H6roult type, whereby the cell includes one or more removable covers mounted side by side, the covers may be removed in connection with operations on the cell and are put back into position when the operations have been completed, wherein at least one cover is designed with at least one side edge that overlaps an adjacent fixed or movable cover and is mounted with a mutual sideways clearance from 10 the fixed or movable cover stated to allow a certain mutual sideways movement between the covers. The present invention will be described in further detail in the following using figures and examples, where: 15 Fig. 1 shows a section of a superstructure of an electrolytic cell seen from the side. Fig. 2 shows a partial section of the superstructure shown in Fig. 1 seen from the end. Fig. 3 shows how the covers are designed, positioned and removed for double anode changes in a partial section B-B of a superstructure (seen from above).

WO 2007/067061 PCT/N02006/000431 2 Fig. 4 shows how the covers are designed, positioned and removed for single anode changes in a partial section B-B of a superstructure (seen from above). 5 Fig. 1 shows a section of a superstructure 1 in which several anode blocks 2 are suspended by means of an anode suspender 3. The anode suspender is fixed with a clamp 4 to an anode beam 5 in conventional manner. In this case, some of the covers have been removed, while covers 6, 7 and 8 are mounted on the superstructure. 10 Fig. 2 shows a partial section of the superstructure shown in Fig. 1, seen from the end. An anode block 2 is suspended from an anode suspender 3 and a cover 6 rests against a frame structure in the superstructure. As Figs. 3 and 4 show, one set of covers on each side of the electrolytic cell consists of 15 top covers 10, 12, 14, 20, 22 and 24 and bottom covers 11, 13, 19, 21, 23 and 25 with equal or different widths that overlap each other, thus creating a tight connection between the covers when they are positioned on the cell. At the same time, this overlapping is such that the seal is maintained even if the covers are pushed together or pulled apart within a given length. The covers next to the corner covers are always top covers. 20 When changing anodes, whether a double change of anodes 15 and 16 or anodes 17 and 18 (see Fig. 3) or a single change of anodes 27, 28, 29 and 30 (see Fig. 4), one bottom cover and two top covers must always be removed. They will always lie so that the bottom cover is in the middle, with one top cover on each side. See Figs. 3 and 4. In this way, 25 there will always be a bottom cover left on the cell on each side of the three covers that are removed. The three covers that are removed can thus be lifted right off. The overlapping is designed so that the covers can be pushed together manually or using a cover gripper mounted on the crane in order to achieve a better position against the 30 covers still in position on the cell when the covers removed are to be put back into position. The width of the overlap and nominal clearance A (see Fig. 4) between the covers determine how far the covers may be pushed together without losing the sealing function. 35 This principle of pushing the covers together in connection with crane-operated changes is important as it results in greater clearance for the covers that are left on the cell during the operation, with the result that less accuracy is required for the crane operation when WO 2007/067061 PCT/N02006/000431 3 the covers are put back into position. After they have been placed in position, they are pushed apart. The handling of the cover(s) stated may be performed with the assistance of a positioning 5 system. Such a positioning system may be based on distance measurement using a laser or similar between at least one point on the manipulator arm and one or more reference points that are preferably mounted on the cell. Such systems belong to the prior art and will, therefore, not be described in further detail here. 10 The advantages of the present invention are: - Simplified operation of covers with a gripper mechanism mounted on a manipulator arm on a crane or a vehicle as the covers are pulled together prior to being lifted out so that the gap between the covers left on the cell is wider. This means that lower accuracy is 15 required for positioning/handling when covers are removed and put back. - Improved enclosure as the gap between neighbouring covers is replaced with overlapping covers (labyrinth seal). 20 - The solution is suitable for both remote-controlled handling using a gripper mechanism on a crane or a vehicle and manual operation by an operator on a hall floor.

Claims

1. A method in connection with handling covers in a superstructure in an electrolytic cell, whereby the cell includes one or more removable covers mounted side by side, the 5 covers are removed in connection with operations on the cell and are put back into position when the operations have been completed, wherein when the covers are removed, the total sideways extent of the covers is reduced initially by the covers being moved together sideways before they are lifted off. 10

2. A method in accordance with claim 1, wherein when the covers are put back into position, they are held in such a way that their total sideways extent is less than when they are back in the cell's superstructure as the covers are spread out sideways after they have been mounted in the superstructure. 15

3. A method in accordance with claim 1 or 2, wherein at least one of the removable covers is designed for handling by a manipulator arm on a crane, a wheeled vehicle or similar.

4. A method in accordance with claim 3, wherein the handling of the cover(s) stated is 20 performed with the assistance of a positioning system.

5. A method in accordance with claim 4, wherein the positioning system is based on distance measurement using a laser or similar between at least one point on the manipulator arm and one or more reference points that are preferably mounted on the 25 cell.

6. A device in connection with covering an electrolytic cell of the Hall-Heroult type, whereby the cell includes one or more removable covers mounted side by side, the covers may be removed in connection with operations on the cell and are put back 30 into position when the operations have been completed, wherein at least one cover is designed with at least one side edge that overlaps an adjacent fixed or movable cover and is mounted with a mutual sideways clearance from the fixed or movable cover stated to allow a certain mutual sideways movement between the covers. 35

7. A device in accordance with claim 6, wherein the covers' side edges are designed so that at least one side edge of a cover has an underlying flange, while the other adjacent cover's side edge has an overlying flange. 5

8. A device in accordance with claim 6 or 7, wherein the movable covers are equipped with at least one ring, a handle or similar for handling them. 5

9. A device in accordance with claim 6, 7 or 8, wherein a heat-resistant seal is mounted between the covers stated.

10. A device in accordance with any one of claims 6 to 9, wherein the cover(s) is(are) made of aluminium or an aluminium alloy. 10

11. A device in accordance with any one of claims 6 to 10, wherein the cover(s) is(are) equipped with steps.

12. A device in accordance with any one of claims 6 to 11, wherein the seal between the 15 covers is a labyrinth seal.

13. A method substantially as herein described.

14. A device substantially as herein described and illustrated. 20