EP0150483B1 - Disposition d'une électrode de fond pour un fond électrique - Google Patents

Disposition d'une électrode de fond pour un fond électrique Download PDF

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Publication number
EP0150483B1
EP0150483B1 EP84116188A EP84116188A EP0150483B1 EP 0150483 B1 EP0150483 B1 EP 0150483B1 EP 84116188 A EP84116188 A EP 84116188A EP 84116188 A EP84116188 A EP 84116188A EP 0150483 B1 EP0150483 B1 EP 0150483B1
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EP
European Patent Office
Prior art keywords
bottom electrode
furnace
contact surface
melting bath
electrode
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.)
Expired
Application number
EP84116188A
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German (de)
English (en)
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EP0150483A3 (en
EP0150483A2 (fr
Inventor
Karl Bühler
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BBC Brown Boveri AG Switzerland
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BBC Brown Boveri AG Switzerland
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Publication date
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Priority to AT84116188T priority Critical patent/ATE34900T1/de
Publication of EP0150483A2 publication Critical patent/EP0150483A2/fr
Publication of EP0150483A3 publication Critical patent/EP0150483A3/de
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Publication of EP0150483B1 publication Critical patent/EP0150483B1/fr
Expired legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/06—Electrodes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces
    • F27D11/08—Heating by electric discharge, e.g. arc discharge
    • F27D11/10—Disposition of electrodes

Definitions

  • the invention relates to an electric oven according to the preamble of claim 1.
  • Such an oven is known for example from FR-PS 382 457.
  • the direct current arc furnace In order to optimize the electrical or thermal conditions, it has proven to be advantageous in the direct current arc furnace to form the arc between one or more electrodes arranged above the melting material and the melting material itself.
  • the bottom electrode For the return of the direct current, at least one electrode in the bottom of the furnace and in contact with the melt, the bottom electrode, is provided.
  • the bottom electrode is subjected to persistent, very high thermal stress, for which materials with a high softening and melting point, for example Graphite.
  • the melt is carburized on the one hand. However, this is particularly undesirable in the production of low-carbon steels.
  • the carbon electrode is consumed, which can weaken the furnace floor and adversely affect the electrical power transmission.
  • the furnace according to FR-PS 382 457 consists of a combined Siemens Martin and arc furnace, with which on the one hand the advantage of the SM furnace - the possibility of performing metallurgical slag work - and on the other hand the advantage of the arc furnace - overheating the melt pool and fine-metallurgical Executing processes - at the same time making them usable.
  • Several floor electrodes are arranged in a curved furnace floor extending in the longitudinal direction.
  • the electromagnetic field of the current flowing through the molten bath from the bottom electrode to the upper electrode causes a bath movement which is particularly strong at the molten bath contact surfaces of the bottom electrodes at which the electromagnetic field strength changes greatly, i.e. at those transition points at which the electrical current passes from the relatively small cross-section of the bottom electrode to the relatively large cross-section of the melting bath.
  • the melt pool flow acts on the melt pool contact surfaces, which now melt back somewhat behind the hearth surface under the influence of temperature, whereby small bays, so-called scour, form. Due to the relatively large kinetic energy of the bath flow, a cross flow (secondary flow) is stimulated in these bays. This further melts the contact surfaces.
  • the melting of the contact surfaces of the bottom electrode at its end facing the molten bath should, however, be avoided as far as possible or at least reduced to an innocuous degree, since the scour (local depressions) remain not only limited to the contact surfaces, but also the adjacent areas of the refractory Grip building material so that crater-shaped recesses are formed.
  • the strength of the bath movement is of course also dependent on the strength of the electromagnetic field. At a given current strength, the longer the magnetic field lines are, the weaker the current, i.e. the larger the circumference or the diameter of the bottom electrode.
  • the invention solves the problem of specifying an electric furnace of the type mentioned, the bottom electrode of which has a long service life.
  • the most noticeable advantage is that the electromagnetic field strength in the boundary layer between the bottom electrode and the melt pool is also continuously - and not abruptly - changed by the continuously successively widening transition of the current-carrying cross section from the bottom electrode to the weld pool. This results in a reduction in the forces causing the melt pool movement. Since the forces acting on the molten bath act on the molten bath perpendicular to the electromagnetic field lines, a bath movement is formed which is directed from the outside against the axis of the bottom electrode.
  • the bottom electrode (s) By arranging the bottom electrode (s) in the protrusion (s) of the furnace, the radially and axially extending melt pool flow, which spreads throughout the melt pool, is prevented from acting directly on the bottom electrode (s) and giving off the heat of the overheated melt to it.
  • the sump required for electrical contacting has to cover almost the entire oven range, but only one sump in the protuberance (s) is sufficient, with an additional minimum dimension of, for example Shredder scrap is sufficient to initiate melting.
  • the design of the hearth surface according to claim 2 has the advantage that the protuberance (s) in which the bottom electrode (s) are located can be adapted to the respective current flow in such a way that a minimal melt bath movement is achieved on the melt bath contact surface.
  • the furnace vessel 2 consists of the vessel bottom 4 together with the refractory lining 4 ′ and the vessel wall 5 together of the refractory lining 5.
  • a carbon electrode 10 is arranged above the melting bath 13 and protrudes through an opening in the furnace cover 3.
  • a cooling ring 3 ′ is provided for cooling the electrode 10.
  • the electrode 10 is held in a holder 11 of an electrode support arm 12.
  • the electrode support arm 12 is connected to an electrode regulation, not shown in FIG. 1.
  • the furnace vessel bottom 4, 4 ′ has a protuberance that is offset laterally to the vertical furnace axis and in which the bottom electrode 6 is arranged eccentrically to the carbon electrode 10.
  • the flat hearth surface 20 is designed in a trumpet shape in the region of the protuberance. This results in a continuous transition from the cross section A of the molten bath contact surface 6 ', 7' of the bottom electrode 6 to the cross section A L in the molten bath 13 at a certain distance from the molten bath contact surface 6 ', 7' of the bottom electrode 6.
  • a L L
  • the bottom electrode 6 is held below the furnace vessel bottom 4 by a schematically illustrated connector 19 designed as a contact sleeve, which at the same time serves to connect the electrical power supply by means of the electrical connecting line 17.
  • non-metallic components 7, 8 are inserted as inserts in the bottom electrode 6, which extend approximately to half of the bottom electrode 6, viewed in the axial direction.
  • these consist of three hollow cylindrical inserts 7 and a central insert 8, as a result of which the metallic components 6 ′ of the molten bath contact surface 6 ′, 7 ′, which are designed in the manner of an annular surface, are mutually divided into narrow zones.
  • the non-metallic components 7, 8 of the bottom electrode 6 consist of a commercially available refractory building material, for example dolomite or magnesite.
  • Fig. 1 schematically shows partial streams 16 of the melt bath movement which run symmetrically to the vertical furnace axis and which have both an axial and a radial component.
  • an axial upward flow from the bottom electrode 6 towards the central region of the molten bath 13 and an axial downward flow from the bath surface towards the central region of the molten bath 13 are formed.
  • the flow 16 is deflected there and is directed radially outwards against the vessel wall 5, 5 '. After redirection, the flow 16 again runs radially towards the furnace interior, sweeps over the inserts 7, 8 acting as dams, so that the molten bath contact surfaces 6 'remain largely unaffected. _ ..._
  • both the metallic 6 'and the non-metallic components 7' of the bottom electrode 6 are adapted to the course of the magnetic field lines 18 which is not concentric with respect to the axis of the bottom electrode 6.
  • This non-concentricity of the magnetic field lines 18 is caused by the relatively high electrical current which is supplied through the electrical connecting line 18 via the contact sleeve 19 to the side of the base electrode.
  • the resulting magnetic field now shifts the electromagnetic field in the bottom electrode 6 in the opposite direction.
  • the metallic 6 'and the non-metallic components 7' are adapted to the magnetic field according to FIG. 2a. This results in an asymmetrical division of the components 6 ', 7' with respect to the axis of the bottom electrode 6 ', as can be seen in FIG. 2a.
  • FIG. 2b shows schematically that the hearth surface 20 is conical, the angle between the hearth surface 20 and the molten bath contact surface 6 ', 7' being at least 20 °.
  • the characteristic curve 21 designates the smallest A L : A ratio for the design of the range 20 and the characteristic curve 21 the largest A L : A ratio. That is, within the limit values defined by the characteristic curves 21, 22 at a distance L: R from the molten bath contact surface 6 ', 7' of the bottom electrode 6, the design of the hearth surface 20 according to the invention is carried out and thereby an optimal reduction of the molten bath flow 16 in the Melt pool contact surface 6 ', 7' reached.
  • the characteristic curves 21, 22 each represent exponential functions which determine the cross-sectional ratio A L : A up to a distance from the molten bath contact surface 6 ', 7' into the furnace hearth 20 - over the entire vertical length of the protuberances - until the furnace hearth is in its horizontal area.
  • Fig. 4 shows a top view of the bottom electrode 6, which is installed in the refractory lining 4 'of the furnace bottom 4.
  • the bottom electrode 6 has an outer and an inner, respectively annular, metallic component 6 'of the molten bath contact surface 6', 7 ', both of which are separated from one another by a refractory insert 7 serving as a dam.
  • the middle metallic component 6 ' on the other hand, consists of four circular sections, each of which interrupt the full circular surface by openings offset by 90 °. In these openings there are struts 7 ′′, which combine the two inserts 7, which are made of a refractory building material, to form a mechanically strong bond.
  • the sectionally interrupted hollow cylindrical design of the dams 7 also offers the advantage that when the melt is emptied "when the arc furnace is tilted, liquid portions of the melt remain between the dams 7 and solidify there again.
  • any number of dams 7, 8 can be arranged within the bottom electrode 6.
  • the circumference and / or diameter of the base electrode 6 is increased for a given current strength and the electrically conductive part thus fixed.
  • 6a to 6c show further embodiments of the metallic component 6 'of the molten bath contact surface 6', 7 'of the bottom electrode 6.
  • 6a shows a meandering 6a, FIG. 4b a rectangular 6b and FIG. 6c a spiral configuration 6c of the metallic part 6 'of the molten bath contact surface 6', 7 ', the non-metallic, refractory components 7' being inserted in complementary fashion.
  • the bottom electrode 6 is assembled into a unitary whole.
  • the components 6 ', 7' of the bottom electrode 6 can extend over the entire axial length of the bottom electrode 6.
  • the metallic component 6 ′ of the bottom electrode 6 is preferably compact in the area of the electrical connecting piece 9 over its entire diameter.
  • the geometric design of the metallic 6 'or non-metallic components 7' are not limited to the exemplary embodiments shown above, and any number of geometric shapes are conceivable.
  • the cross-section of the bottom electrode (s) 6 is selected to be as large as possible, and that the electrode components 6 ', 7' run in the direction of the electrical field lines, the length of the electrode components 6 ', 7' in relation to their width should be large.
  • the furnace vessel 4, 4 '; 5, 5 'and likewise the oven hearth 20 can be both rotationally symmetrical and non-rotationally symmetrical.
  • the trumpet-shaped or conical protuberances of the hearth surface 20, at the lower end of which the bottom electrode (s) are arranged, can be designed continuously, as shown in FIGS. 1, 2b and 3. But they can also be discontinuous, i.e. gradually, with paragraphs, be designed.
  • the present invention also remains not only limited to cylindrical bottom electrodes 6.
  • Elliptical, square, rectangular or polygonal cross-sectional shapes can also be used.
  • one or more base electrodes 6 can be hollow-cylindrical or at least partially hollow-cylindrical.
  • any number of bottom electrodes 6 can be installed in the furnace vessel bottom 4, 4 ', specifically at any location in the furnace vessel bottom 4, 4'.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Furnace Details (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Discharge Heating (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Glass Compositions (AREA)
  • Organic Insulating Materials (AREA)
  • Inorganic Insulating Materials (AREA)
  • Electrolytic Production Of Metals (AREA)

Claims (3)

1. Un four électrique, en particulier un four à arc de courant continu, pour la fusion de métaux, avec au moins une électrode du fond (6), qui est disposée dans le fond de l'enveloppe (4) du four, la surface de la sole (20) du four s'élargissant successivement à partir de l'électrode du fond (6) vers l'intérieur de l'enveloppe du four dans la zone de l'électrode du fond (6), caractérisé en ce que l'électrode du fond (6) est disposée à l'extrémité inférieure de protubérances de l'enveloppe du four qui diminue vers l'extérieur en forme d'une trompette, ou dans le cas limite, coniquement, le rapport entre la section transversale (AL) de la surface de la sole (20) et la section transversale (A) de l'électrode du fond (6) dans sa zone de contact avec le bain de fusion (6', 7') étant choisi, dans le cas où les protubérances ont une forme semblable à une trompette dans une plage de
Figure imgb0002
dans lequel AL est la surface de la sole qui est produite par une section transversale à une distance axiale L à partir de la zone de contact avec le bain de fusion vers l'intérieur de l'enveloppe du four et AL et A sont exprimées en m2, L est la distance
axiale à partir de la zone de contact avec le bain de fusion (6', 7') vers l'intérieur de l'enveloppe du four, en m, et R est le rayon de l'électrode du fond (6) dans sa zone de contact avec le bain de fusion, et en ce que, dans le cas de la forme conique des protubérances, la surface latérale de son cône forme avec la zone de contact avec le bain de fusion de l'électrode du fond (6) un angle d'au moins 20°.
2. Un four électrique selon la revendication 1, caractérisé en ce que la surface de la sole (20) possède, dans la zone de l'électrode du fond (6) des rayons de courbure différents dans les limites définies par la fonction exponentielle ou que la surface de la sole (20) a des cônes avec des angles différents.
EP84116188A 1984-01-31 1984-12-22 Disposition d'une électrode de fond pour un fond électrique Expired EP0150483B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84116188T ATE34900T1 (de) 1984-01-31 1984-12-22 Bodenelektrodenarordnung fuer einen elektrischen ofen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH444/84 1984-01-31
CH44484 1984-01-31

Publications (3)

Publication Number Publication Date
EP0150483A2 EP0150483A2 (fr) 1985-08-07
EP0150483A3 EP0150483A3 (en) 1985-09-25
EP0150483B1 true EP0150483B1 (fr) 1988-06-01

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ID=4187164

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EP84116188A Expired EP0150483B1 (fr) 1984-01-31 1984-12-22 Disposition d'une électrode de fond pour un fond électrique

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US (1) US4615035A (fr)
EP (1) EP0150483B1 (fr)
JP (1) JPS60181583A (fr)
AT (1) ATE34900T1 (fr)
BR (1) BR8500387A (fr)
DE (1) DE3471867D1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2602318B1 (fr) * 1986-08-01 1988-11-10 Clecim Sa Four a arc alimente a partir d'une source de courant continu pour la fusion continue de ferrailles
DE3817381A1 (de) * 1988-05-18 1989-11-30 Mannesmann Ag Verschleissarme elektrode in gleichstromlichtbogenofen
US5189682A (en) * 1989-10-23 1993-02-23 Nkk Corporation Method for increasing the efficiency of a direct current electric arc furnace
DE4022720A1 (de) * 1990-07-17 1992-01-23 Flohe Gmbh & Co Untergefaess eines gleichstromlichtbogenofens
US5255284A (en) * 1991-11-04 1993-10-19 Deutsch Voest-Alpine Industrieanlagenbau Gmbh Anode for an electic arc furnace utilizing electrode segments
US6137822A (en) * 1998-02-27 2000-10-24 Nkk Steel Engineering, Inc. Direct current arc furnace and a method for melting or heating raw material or molten material
US9643129B2 (en) 2011-12-22 2017-05-09 Bl Technologies, Inc. Non-braided, textile-reinforced hollow fiber membrane
CA3033192C (fr) * 2016-08-12 2023-06-06 Boston Electrometallurgical Corporation Assemblage de collecteur de courant sans fuite pour recipient metallurgique et procedes de fabrication

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR382457A (fr) * 1906-12-07 1908-02-07 Electrometallurgique Procedes Four mixte électrométallurgique

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB135674A (fr) * 1900-01-01
US1167176A (en) * 1915-02-23 1916-01-04 Frank William Highfield Smelting of ores and apparatus therefor.
NO123433B (fr) * 1967-06-10 1971-11-15 Tohoku Special Steel Works Ltd
SE419929B (sv) * 1974-11-25 1981-08-31 Asea Ab Smeltkontaktelektrod for likstromsmatad ljusbagsugn
US4125737A (en) * 1974-11-25 1978-11-14 Asea Aktiebolag Electric arc furnace hearth connection
FR2381987A1 (fr) * 1977-02-23 1978-09-22 Asea Ab Connexion de sole pour un four a arc alimente en courant continu
FR2441313A1 (fr) * 1978-11-10 1980-06-06 Siderurgie Fse Inst Rech Electrode refroidie pour mise en contact avec un metal en fusion

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR382457A (fr) * 1906-12-07 1908-02-07 Electrometallurgique Procedes Four mixte électrométallurgique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Stahl und Eisen, (1983), Febr., no. 3, Düsseldorf, pp. 133(49)-137(53) *

Also Published As

Publication number Publication date
JPS60181583A (ja) 1985-09-17
EP0150483A3 (en) 1985-09-25
EP0150483A2 (fr) 1985-08-07
BR8500387A (pt) 1985-09-10
DE3471867D1 (en) 1988-07-07
US4615035A (en) 1986-09-30
ATE34900T1 (de) 1988-06-15

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