EP0150483A2 - 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
EP0150483A2
EP0150483A2 EP84116188A EP84116188A EP0150483A2 EP 0150483 A2 EP0150483 A2 EP 0150483A2 EP 84116188 A EP84116188 A EP 84116188A EP 84116188 A EP84116188 A EP 84116188A EP 0150483 A2 EP0150483 A2 EP 0150483A2
Authority
EP
European Patent Office
Prior art keywords
bottom electrode
electrode
metallic
molten bath
contact surface
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.)
Granted
Application number
EP84116188A
Other languages
German (de)
English (en)
Other versions
EP0150483B1 (fr
EP0150483A3 (en
Inventor
Karl Bühler
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.)
BBC Brown Boveri AG Switzerland
Original Assignee
BBC Brown Boveri AG Switzerland
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 BBC Brown Boveri AG Switzerland filed Critical BBC Brown Boveri AG Switzerland
Priority to AT84116188T priority Critical patent/ATE34900T1/de
Publication of EP0150483A2 publication Critical patent/EP0150483A2/fr
Publication of EP0150483A3 publication Critical patent/EP0150483A3/de
Application granted granted Critical
Publication of EP0150483B1 publication Critical patent/EP0150483B1/fr
Expired legal-status Critical Current

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Classifications

    • 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 DC arc furnace has been used to optimize the electrical and thermal conditions proved to be advantageous to form the arc between one or more electrodes arranged above the melting material and the melting material itself. At least one electrode in the bottom of the furnace and in contact with the melt, the bottom electrode, is provided for the return of the direct current.
  • the bottom electrode is exposed to a very high thermal load for which materials with a high softening and melting point, such as graphite, are suitable.
  • the melt is carburized on the one hand. However, this is particularly undesirable in the manufacture of low-carbon chairs.
  • 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 processes perform - can be used at the same time.
  • the electromagnetic field of the current flowing through the weld pool from the bottom electrode to the upper electrode causes a bath movement that is particularly strong at the melt contact surfaces of the bottom electrodes, at which the electromagnetic field strength changes strongly, i.e. at those transition points where the electric Current passes from the relatively small cross-section of the bottom electrode to the relatively large cross-section of the weld pool.
  • 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 colts are now also emptied and cavities are created which make subsequent electrical contacting of solid components to be melted more difficult.
  • the strength of the bath movement is of course also dependent on the strength of the electromagnetic field. This becomes weaker at a given current strength, the longer the magnetic field lines are, 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.
  • an essential characteristic of the invention is that on the one hand the hearth surface is designed in such a way that the ratio of the cross-section of the hearth surface to the cross-section of the bottom electrode in its molten bath contact surface lies in a range that is indicated by an exponential function or on the other hand that the hearth surface is at least approximately frustoconical and the surface of the cone with the molten bath contact surface forms an angle 04 of at least 20 °.
  • the most noticeable advantage is that the electromagnetic field strength is continuously - and not abruptly - changed in the boundary layer between the bottom electrode and the melt pool due to the continuous, progressively 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 3 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.
  • both the metallic and the non-metallic component of the molten bath contact surface have a length substantially in the direction of the electromagnetic field of the current-carrying floor electrode that is greater than its width.
  • the melting depth of the metallic molten bath contact surface can be kept almost constant (staisty) over the entire melting process, since the action of the bath flow and the associated intensive heat transfer from the molten pool to the metallic contact surface is greatly reduced by the dams of the non-metallic component and by the relatively small width of the metallic contact surface in relation to its length. Due to the small width of the gap, the differences in the electromagnetic field strength in the gap are small. This results in correspondingly small forces driving the melt liquid in the gap.
  • the temperature of the molten bath in the gap corresponds to that of the superheated molten bath and is at the bottom, near the contact surface, equal to or slightly below the melting temperature. This temperature difference corresponds to a difference in the specific density of the liquid, which is lighter at the top and heavier at the bottom. This difference in density of the liquid in the gap counteracts movement of the melt liquid in the gap.
  • the metallic and the non-metallic electrode component is alternatively at least partially hollow-cylindrical or meandering or rectangular or spiral-shaped, the proportion of the area of the metallic component being 10 to 70%, in particular 30 to 60%, of the total melt pool contact area.
  • the embodiment according to claim 6 provides a cylinder made of a metal or a non-metal within the hollow cylindrical or meandering or rectangular or spiral configuration of both electrode components.
  • the advantage according to claims 5 and 6 can be seen in the fact that these constructional measures increase the service life of the base electrode and reduce the manufacturing costs.
  • the struts according to claim 7 have the advantage that the dams of the non-metallic component of the bottom electrode can be mutually supported when the metallic contact surface is melted back.
  • the improved mechanical stability has a particularly favorable effect in arc furnaces with high outputs which have a strong bath movement in the vicinity of the molten bath contact surface of the base electrode.
  • the displacement of the struts, both in the radial and in the circumferential direction of the base electrode results in a further mechanical reinforcement of the non-metallic component of the base electrode in its molten bath contact surface.
  • the advantage of the dislocations can be seen in the fact that the width of the contact surface gap can be limited in relation to the length.
  • the choice of the ratio of the thickness of the metallic to the non-metallic constituent of the bottom electrode in its molten bath contact surface according to claim 8 has the advantage that the electrically conductive contact surfaces can be divided into narrow zones that remain largely unaffected by the molten bath flow, and the other can The diameter or the circumference of the bottom electrode can be specifically dimensioned for a predictable bath flow.
  • the metallic component of the bottom electrode preferably has chemical contents similar to the molten bath and its non-metallic component consists of a commercially available refractory building material. This enables both an economical production of the bottom electrode and an economical arc furnace operation.
  • the furnace vessel 2 consists of the vessel bottom 4 together with the fires solid lining 4 ', and from the vessel wall 5 together with 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 melt pool contact surface 6 ', 7' of the bottom electrode 6 to the cross section A L in the melt pool 13 at a certain distance from the melt pool contact surface 6 ', 7' of the bottom electrode 6.
  • the ratio of A L : L is referred to in more detail in the description of FIG. 3.
  • 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 one 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 indicate the non-concentric course of the magnetic field lines 18 with respect to the axis of the bottom electrode 6 fits.
  • 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 to the electrical connecting line 18.
  • 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 formation 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 in the molten bath flow 16 in the melt pool contact surface 6 ', 7'.
  • the characteristic curves 21, 22 each represent exponential functions which represent the cross-sectional ratio A L : A up to a distance from the Fix the melt bath contact surface 6 ', 7' into the oven hearth 20 - over the entire vertical length of the protuberances - until the oven hearth transitions into 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 hollow cylindrical configuration of the dams 7, which is interrupted in sections, 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 again there.
  • any number of dams 7, 8 can be arranged within the bottom electrode 6.
  • the circumference or diameter of the base electrode 6 is increased at a predetermined current and the electrically conductive part of the base electrode 6 determined thereby.
  • 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 also 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 both be continuous. 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 bottom 4, 4 'of the furnace vessel, at any location in the bottom 4, 4' of the furnace.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Discharge Heating (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Furnace Details (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)
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 true EP0150483A2 (fr) 1985-08-07
EP0150483A3 EP0150483A3 (en) 1985-09-25
EP0150483B1 EP0150483B1 (fr) 1988-06-01

Family

ID=4187164

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84116188A Expired EP0150483B1 (fr) 1984-01-31 1984-12-22 Disposition d'une électrode de fond pour un fond électrique

Country Status (6)

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

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2602318A1 (fr) * 1986-08-01 1988-02-05 Clecim Sa Four a arc alimente a partir d'une source de courant continu pour la fusion continue de ferrailles
WO1989011774A1 (fr) * 1988-05-18 1989-11-30 Mannesmann Ag Electrode a usure reduite pour fours a chauffage direct par arc de courant continu
DE4022720A1 (de) * 1990-07-17 1992-01-23 Flohe Gmbh & Co Untergefaess eines gleichstromlichtbogenofens
EP0541044A2 (fr) * 1991-11-04 1993-05-12 Deutsche Voest-Alpine Industrieanlagenbau Gmbh Four à arc à courant continu
US9643129B2 (en) 2011-12-22 2017-05-09 Bl Technologies, Inc. Non-braided, textile-reinforced hollow fiber membrane

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5189682A (en) * 1989-10-23 1993-02-23 Nkk Corporation Method for increasing the efficiency of a direct current electric arc furnace
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
CN115142094A (zh) * 2016-08-12 2022-10-04 波士顿电冶公司 用于冶金容器的无泄漏集电器组件和制造方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB135674A (fr) * 1900-01-01
FR382457A (fr) * 1906-12-07 1908-02-07 Electrometallurgique Procedes Four mixte électrométallurgique
FR1570814A (fr) * 1967-06-10 1969-06-13
FR2292397A2 (fr) * 1974-11-25 1976-06-18 Asea Ab Dispositif de connexion de la sole d'un four a arc a courant continu
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

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1167176A (en) * 1915-02-23 1916-01-04 Frank William Highfield Smelting of ores and apparatus therefor.
US4125737A (en) * 1974-11-25 1978-11-14 Asea Aktiebolag Electric arc furnace hearth connection

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB135674A (fr) * 1900-01-01
FR382457A (fr) * 1906-12-07 1908-02-07 Electrometallurgique Procedes Four mixte électrométallurgique
FR1570814A (fr) * 1967-06-10 1969-06-13
FR2292397A2 (fr) * 1974-11-25 1976-06-18 Asea Ab Dispositif de connexion de la sole d'un four a arc a courant continu
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

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) *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2602318A1 (fr) * 1986-08-01 1988-02-05 Clecim Sa Four a arc alimente a partir d'une source de courant continu pour la fusion continue de ferrailles
EP0269465A1 (fr) * 1986-08-01 1988-06-01 Clecim Procédé de fusion en continu de ferraille dans un four électrique à courant continu et four électrique pour la mise en oeuvre du procédé
WO1989011774A1 (fr) * 1988-05-18 1989-11-30 Mannesmann Ag Electrode a usure reduite pour fours a chauffage direct par arc de courant continu
DE3817381A1 (de) * 1988-05-18 1989-11-30 Mannesmann Ag Verschleissarme elektrode in gleichstromlichtbogenofen
DE4022720A1 (de) * 1990-07-17 1992-01-23 Flohe Gmbh & Co Untergefaess eines gleichstromlichtbogenofens
EP0541044A2 (fr) * 1991-11-04 1993-05-12 Deutsche Voest-Alpine Industrieanlagenbau Gmbh Four à arc à courant continu
EP0541044A3 (en) * 1991-11-04 1993-09-15 Voest Alpine Ind Anlagen Dc arc furnace
TR26434A (tr) * 1991-11-04 1995-03-15 Voest Alpine Ind Anlagen DüZ AKIMI ELEKTRIK ARK OCAGI ANOD.
US9643129B2 (en) 2011-12-22 2017-05-09 Bl Technologies, Inc. Non-braided, textile-reinforced hollow fiber membrane

Also Published As

Publication number Publication date
EP0150483B1 (fr) 1988-06-01
BR8500387A (pt) 1985-09-10
ATE34900T1 (de) 1988-06-15
US4615035A (en) 1986-09-30
DE3471867D1 (en) 1988-07-07
JPS60181583A (ja) 1985-09-17
EP0150483A3 (en) 1985-09-25

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