US3170862A

US3170862A - Reinforced concrete structure in an electrolytic furnace house for producing aluminum

Info

Publication number: US3170862A
Application number: US144095A
Authority: US
Inventors: Hegland Reidar
Original assignee: Alusuisse Holdings AG
Current assignee: Alcan Holdings Switzerland AG
Priority date: 1960-10-14
Filing date: 1961-10-10
Publication date: 1965-02-23
Anticipated expiration: 1982-02-23
Also published as: CH381409A; DE1136496B; ES271088A1; SE318116B; GB929822A

Description

Feb. 23, 1965 R. HEGLAND 3,170,362

REINFORCED CONCRETE STRUCTURE IN AN ELECTROLYTI FURNACE HOUSE FOR PRODUCING ALUMINUM Filed Oct. 10, 1961 f 5. 0 m b 7 3 2 m Z Z P 3 .....p B 9 2 7 Z a a 7 4 10. 1 7 m 4 Z T, 5 7 7 A 5 7 z z a M Z a a o 7 M 3 2 5 I: f 1i 6 3,170,862 1 REINFORCED CONCRETE STRUCTURE IN AN ELECTROLYTIC FURNACE-HOUSE FOR PRO- DUCING ALUMINUM f r Reidar 'Heglan'd, Zurich, Switzerland, assignor to Swiss Aluminium LtdL, Chippis, Switzerland, a joint-stock company of Switzerland Filed. Oct. 10,1961, ser. No. 144,095

Claims priority, application Switzerland, Oct. 14, 1960,

9 Claims.. '(Cl. 204-244) .The present invention relates to a reinforced concrete structure in an electrolytic furnace house for producing aluminum. a I

Electrolytic furnaces used in the production of aluminum froma fluoride melt by the usual processes include essentially rectangular pots arranged in straight rows in a. furnace house and anode structures including anodes .dip-

ping into the pots. The pots may be situated at fioor levelv and are advantageously directly supported on foundations or: bracketsa'rranged under the floor. These foundations or brackets, and indeed the whole of the lower part of the building, normally" consists of reinforced concrete. The anode structures of the furnaces are'carried'by steel supports or by pillars of reinforced concrete, which may extend up from the floor or which may have their-foundations below the floor. V In modern electrolytic installations, a large number 0 furnaces, all requiring a current of 80,000 amperes and even more, are connected in series. In such installations, potential differences of several hundred volts wtih respect to earth exist; on the rectifying side, the potential difference may be up to 1,000 volts and even more. It is practically'impossible to electrically insulate completely all the furnaces, bus bars and Waste gas conduits from the building structure. Hence, stray currents will alwaysfiow into the reinforced concrete structure. Concrete, being an electric conductor when damp, and being a semi-conductor when dry, c annot under any circumstances be regarded as-an insulator. Stray cur-rents flowing through the concrete may reach the reinforcement and flow through said reinforcement, heating thereby the reinforcement. The resulting thermal expansion of the reinforcement causes cracks in-the concrete, and the electrolytic action of the current anodically oxidizes the ferrous reinforcement,

causinggit to rust. Also, stray currents create current losses and are a source of, danger to the operators.

One object of the present invention is to provide anew and improved reinforced concrete structure which supports the electrolytic furnaces ina furnace orpot'house V for the pro ductionaof aluminum, and which avoidsthe drawbacks of theprior art described above.

; According to thepresent invention, the:reinforced and eventually from the walls of the building.

The complete structure normally includes a sub-floor,

concretewtructure for; supportingthe" furnace is divided into. separate sections, which are electrically insulated in yer ti; call and-horizontal. direction fro'rn one another, from earth I one another. What is important is to divide the structure; a

such sections, This sectionalized structure advantageously rests on foundation pedestals extending into the ground; and is separated fronrthe'se pedestals-by electrically in- "sulating layers. j j t The .sections may constitute is ds of reinforced'com' 'crete which are lvertically insulatedfzfrom one auother by the spacebetw een thernfthe furnace pots beingarr'ang'e'd between the islands. -The floor may ib ey formed by cohjcret slabsl'garried by but electrically insulated from their that consists of the floor a nd the vertical supports into islands, and by bridging islands and electrically insulated from them. An island may support more than one floor slab and these slabs are; preferably electrically insulated from one another Such.

slabs extending between the slabs onislands may be cast in situ or be pre-cast. The electrical insulation may be formed by layers of a a plastic, which may be an-epoxy-or polyester resin applied by pouring or spraying and which is preferably reinforced by glass fibres. 'For instance, the slabs of the floor may,

be made, and insulated from the concreteisland that supports them, by first pouring a layer of polyester resin V I onto the island. A glass fibre mat is placed on this layer and pressed in, and another layer of polyester resin may be applied. After the layer of the resinhas hardened,

the floor slabs are cast in concrete and the separating joints between them are filledby pouring in polyester v-resin. E lectrical'measurements madebetween a copper plate placed on a floor slab and electrodes concreted into an island below it have shown that, with 220volts A.C'.

across the electrodes the resistance between them is multiplied more'than one hundred times bythe intermediate .layer of plastic, provided the concrete is:fully set;

The preferred construction according to the invention will now be described in detailwith reference to the accompanying drawings, in which: 7

FIGURE 1 is a horizontal somewhat diagrammatic sec Y tion of a part of a furnace house embodying the present invention, taken on lines .11 of FIG. 2;

FIGURE 2 is a somewhat diagrammatic section through the whole width of the furnace house, taken on the lines 22 of FIGURE 1; and

7 FIGURE? shows in section a modification of a portion of thestructure of the furnace house in accordance with the present invention.

Referring to FIGS. 1 and 2 of the drawings,tthe furnace house shown has side walls 15 spanned by a floor 17 *which lies above abasernent chamber 13. Furnace pots Z-Containing fiuoridetmelts into which anodes 19 dip are disposed at the level of 11611001 17- inholesleft in the floor, and each pot is carried on aflgrate 9 which, pro jects= laterally to rest on I-girders 10, TheI-girders 10 are carried by the. reinforced concrete structure which as a whole'rests on'a sub-structure comprising foundation pedestals. 11 extending into the ground. Thefreinforced concrete structure comprises side-supports land centralf supports (1a built as separate islands with cantilever extensions 21 and withbrackets 8 forthe support of the girders It j' lhese brackets 8 are-constructed so that the[ pots ,2 can be-lowered between the brackets'an'd removed for repair Or eplacemenL,

The reinforced concrete structure that 'supporfts' thefun naces is insulated from the substructurethatconsists 2 consi'sting VI of a polyester resin reinforcedby glass'fibr'e. v Thecon- '1 i esse ntially"the pedestals 11 by"tfoughs nections between the reinforcedc'bncrete structure and the pedestals 11 may be formed by suspending each trough 12 in the shuttering in which the corresponding pedestal is formed, and pouring'the concrete herieath the trough toformthe corresponding pedestal.

The pots 2 arearran ged in two, rows; and in each row'," f the openings that'receive the pots a're all connected with} one another, so that there is a continuous division of the i floor into three longitudinal parts 3a, 3b, 3c,electricallyseparated from one another. 4

' v The brackets 8 have 1load-bearing'coverings 7 on which the girders 10 rest andeach covering 7 is electrically inthe remainder of the *bracket by insulation 127. i l V i 1 The extensions 21 of the side supports Iproject inv wardlyfrom'each'side of the houserandhave' narrow ends extending. intotl'ie spaces between adjacent furnace pots sulated from Patented Feb. 23, 1965 U 2. In addition, the extensions 21 of the central vertical supports 101 have similar narrow ends projecting outwardly from the center line of the house into the same spaces.

The floor 17 is composed in part of concrete slabs on the tops of the islands 1 and 1a separated by insulations 20 and in part of slabs 4 bridging the islands. The slabs 5 are formed on top of insulating layers 6 in the manner described above, and in the parts of the floor between the rows of furnace pots 2, these slabs 5 do not wholly cover the tops of the islands but extend short of the sides of these islands to define ledges on these islands to receive the ends of the slabs 4, which are prefabricated. Insulation 22 is interposed betweenthe slabs 4 and these ledges.

Pillars 13 provided to support the anodic parts of the furnaces rest on the cantilever extensions with the interposition of insulation 14. These pillars 13 carry the anodes 19 in the usual way, the anodes being fed with current through bus bars 23 and conductors 24.

The furnace house, of course, includes a superstructure including walls and a roof not shown and this is insulated from the structure that carries the furnace pots 2 by the insulating layer 6. Alternatively, the walls 15 may be of a metal framework 16 with a covering, as shown in FIGURE 3, and in such a case a trough 25, similar to the trough 12 may be let into the top of the structure immediately below the wall, and steel pins and plates 26 may then be concreted into the trough to form supports for the framework 16.

If it is necessary for reinforcement to extend through any joint, e.g. through the joint between the pillars 13 and extensions 21 beneath them, the reinforcing rods will tend to conduct current and destroy the effect of the insulation, such as that shown at 14. To remedy this, the reinforcing rods may be coated with a firmly adherent coating of an electrical insulating plastic, to which grains of sand may be bonded, all as described and claimed in copending application Serial No. 120,624 filed June 29, 1961, now abandoned.

The different insulations referred to may comprise a resin, such as an epoxy resin, or a polyester resin reinforced with glass fibres, as described.

What isclaimed is:

1. A furnace house for furnace pots used in the electrolytic production of aluminum, comprising side walls, and means for supporting a plurality of furnace pots between said walls comprising a foundation structure, a floor supporting reinforced concrete structure supported on said foundation structure and constituting a plurality of sections extending between said walls and said furnace pots, means for supporting the furnace pots on saidsections, and means electrically insulating said sections in all directions from eachother, from the earth, from said foundation structure and from said furnace walls.

walls, and floor slabs bridging said sections and electrically insulated therefrom.

5. A furnace house for furnace pots used in the electrolytic production of aluminum, comprising side walls, and means for supporting a plurality of furnace pots between said walls arranged end to end substantially in a row along one of said walls and comprising .a foundation structure, a floor supporting reinforced concrete structure supported on said foundation structure and constituting a plurality of sections, at least some of which are arranged along said wall and extend from the Vicinity of said wall inwardly towards the vicinity of said row of furnace pots, means for supporting the furnace pots on said sections, and means electrically insulating said sections in all directions from each other, from the earth, from said foundation structure and from said furnace walls.

6. A furnace house for furnace pots having anodic parts and used in the electrolytic production of aluminum, comprising side walls, and means for supporting a plurality of furnace pots in a row end to end between said walls comprising a foundation structure, a floor supporting reinforced concrete structure supported on said foundation structure and constituting a plurality of sections extending in spaced relationship along said row of pets on opposite sides of said row and extending into the regions between the ends of said pots, means for supporting the furnace'pots on said sections, means for supporting said anodic parts on said sections in the regions between the ends of said pots, and means electrically insulating said sections in all directions from each other, from the earth, from said foundation structure, from said furnace walls and from said anodic parts.

7. A furnace house'for furnace pots used in the electrolytic production of aluminum comprising side walls, and means for supporting between said walls a plurality of furnace pots arranged in substantially parallel rows and comprising a foundation structure, a floor supporting reinforced concrete structure supported on said'foundation structure and constituting a plurality ofsections, some of which extend from some of said furnace walls inwardly towards the adjacent rows of pots and others of which .extend between the rows of pets, means for supporting the furnace pots on said sections, and means electrically ported on said foundation structure and constituting a plurality of sections extending in spaced relationship along said row of pots on opposite sides of said row and extending into the regions between the end of the pots, means i for supporting the furnace pots on said sections, and

- means electrically insulating said sections in all directions said foundation structure comprises foundation pedestals extending into the ground and said sections have supports seated on said pedestals but separated therefrom by electrically insulating layers. V

4. A furnace house for furnace pots used in the electrolytic production of aluminum, comprising side walls on .said sections, means electrically insulating said sec.-

tions in, all directions from each other, from the earth,

from said foundation structure and from said furnace insulated from said sections.

from each other, from the earth, from said foundation structure and from said furnace walls, and bridging concrete slabs extending between said sections and electrically 9. A furnace house for furnace pots having anodic parts and used in the electrolytic production of aluminum, comprising side walls, means for supporting between said walls a plurality of furnace pots arranged in a plurality of substantially parallel rows with the pots in each row extending end to end comprising a foundation structure, a floor supporting reinforced concrete structure supported on saidfoundation structure and constituting a plurality of sections, some of which are spaced along the rows of pots and extend from some of said furnace walls inwardly towards the adjacent rows of pots into the regions between of the pots in the latter roWs of pets, means for supporting the furnace pots on said sections, means for supporting the anodic parts on said sections between the ends of the pots, and means electrically insulating said sections in all directions fiom each other, from the earth, from said foundation structure, from said furnace wall, from said anodic parts and from said pots, and floor slabs bridging said sections along the rows of pots and electrically insulated from said sections.

References Cited in the file of this patent UNITED STATES PATENTS Hood Apr. 15, 1958 Syz et al. Feb. 17, 1959 Conway Apr. 18, 1961 Hegland July 3, 1962

Claims

1. A FURNACE HOUSE FOR FURNACE POTS USED IN THE ELECTROLYTIC PRODUCTION OF ALUMINUM, COMPRISING SIDE WALLS, AND MEANS FOR SUPPORTING A PLURALITY OF FURNACE POTS BETWEEN SAID WALLS COMPRISING A FOUNDATION STRUCTURE, A FLOOR SUPPORTING REINFORCED CONCRETE STRUCTURE SUPPORTED ON SAID FOUNDATION STRUCTURE AND CONSTITUTING A PLURALITY OF SECTIONS EXTENDING BETWEEN SAID WALLS AND SAID FURNACE POTS, MEANS FOR SUPPORTING THE FURNACE POTS ON SAID SECTIONS, AND MEAND ELECTRICALLY INSULATING SAID SELECTIONS IN ALL DIRECTIONS FROM EACH OTHER, FROM THE EARTH, FROM SAID FOUNDATION STRUCTURE AND FROM SAID FURNACE WALLS.