EP0133926A1 - Electrode de fond pour four à arc à courant continu - Google Patents

Electrode de fond pour four à arc à courant continu Download PDF

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Publication number
EP0133926A1
EP0133926A1 EP84108020A EP84108020A EP0133926A1 EP 0133926 A1 EP0133926 A1 EP 0133926A1 EP 84108020 A EP84108020 A EP 84108020A EP 84108020 A EP84108020 A EP 84108020A EP 0133926 A1 EP0133926 A1 EP 0133926A1
Authority
EP
European Patent Office
Prior art keywords
bottom electrode
electrode
furnace
section
cross
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
EP84108020A
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German (de)
English (en)
Other versions
EP0133926B1 (fr
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
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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 AT84108020T priority Critical patent/ATE27059T1/de
Publication of EP0133926A1 publication Critical patent/EP0133926A1/fr
Application granted granted Critical
Publication of EP0133926B1 publication Critical patent/EP0133926B1/fr
Expired legal-status Critical Current

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Classifications

    • 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
    • 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

Definitions

  • the invention relates to an electric oven according to the preamble of claim 1.
  • Such an oven is known for example from CH-PS 452 730.
  • 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 switch the arc between one or form several electrodes (s) 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.
  • materials with a high softening and melting point such as 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.
  • bottom electrodes are used whose zone in connection with the melt also has the same chemical contents as the melt itself.
  • the cooling takes place at the end region of the bottom electrode facing away from the furnace vessel by convection with air, whereby this end region consists of a metal with good heat-conducting and current-carrying properties, for example copper. It is a so-called two-substance base electrode.
  • the cooler performance must be adapted to the operational requirements. This can be increased by oversizing an air cooler. In the long run, however, this would lead to unsatisfactory results.
  • liquid cooling is ideal for cooling a bottom electrode.
  • appropriate protective measures must be taken so that liquid metal does not come into contact with the coolant.
  • the invention has for its object to provide an electric furnace of the type mentioned, in whose bottom electrode has a long life.
  • An essential characteristic of the invention is that the ratio of the cross section of the bottom electrode in the furnace vessel bottom to the cross section in the furnace hearth surface is chosen to be at least 1.4: 1, preferably 2: 1.
  • the undesirably small temperature gradient in the region of the base electrode near the hearth is limited to a small axially extending section, and that the temperature gradient immediately immediately rises relatively steeply in the direction of the furnace vessel bottom.
  • the result of this is that the temperature of the molten bath remains concentrated on the end face of the bottom electrode in the furnace hearth area, and that no or only to a very limited extent a change in the position of the liquid / solid boundary layer between the melt and the bottom electrode can take place. This significantly increases the life of the bottom electrode.
  • At least one molded body supplementing the base electrode is provided, which is made of a refractory material and has a lower conductivity than the base electrode, the shape of the molded body being at least in one Partial area is adapted to the geometric configuration and the shaped body has an increasing cross section in the direction of the interior of the furnace vessel.
  • the molded body encloses the base electrode like a sleeve or is arranged in a funnel-shaped recess which extends from the end face of the base electrode facing the interior of the furnace vessel in the axial direction approximately to the region of the furnace vessel base.
  • the bottom electrode tapers towards the inside of the furnace, it can still be replaced from the outside towards the inside of the furnace. This saves time-consuming and extensive work in the oven vessel cooker that would actually be required to dismantle the bottom electrode in accordance with its geometric shape - namely from the inside out.
  • bottom electrodes made of an iron alloy are used, on the one hand, and two-substance electrodes, on the other hand, in which, on the side facing away from the weld pool, the more electrically and thermally more conductive material, preferably copper, is used.
  • the two metals of the two-substance electrode are preferably welded together.
  • the ratio of the average cross section to the length of the base electrode is equal to a factor multiplied by the electric current.
  • the factor for a one-piece iron alloy electrode is in a range of ⁇ f ⁇
  • for a two-substance electrode in a range of ⁇ f . If the electrodes are dimensioned in a range according to the formula above, the floor electrodes are almost exclusively heated by the current, with cooling on the side facing away from the inside of the furnace vessel, and give a temperature on the end face of the base electrode facing the furnace hearth surface that is the temperature of the Melting bath corresponds.
  • Fig. 1 shows the arc furnace 1 with furnace vessel 2 and furnace lid 3, the furnace vessel 2 from the vessel bottom 4, the vessel wall 5, the refractory lining of the furnace bottom 4 ', and the refractory lining of the Vessel wall 5 'exists.
  • a carbon electrode 8 is arranged above the melting bath 13 and protrudes through an opening in the furnace cover 3.
  • a cooling ring 3 ' is arranged for cooling the electrode 8.
  • the electrode 8 is held in a holder 9 of an electrode support arm 11.
  • the electrode support arm 11 is in turn connected to an electrode regulating device, not shown in FIG. 1.
  • the bottom electrode 7a In the vessel bottom 4, 4 ', the bottom electrode 7a according to the invention can be seen, which is enclosed in a sleeve-like manner by the complementary part 10 made of refractory material.
  • the bottom electrode 7a has a conical shape that tapers in the direction of the interior of the vessel, which extends from the bottom 4 of the furnace up to the surface 16 of the furnace.
  • the part 10 which supplements it widens in the direction of the interior of the vessel.
  • the bottom electrode 7a is held below the furnace vessel bottom 4 by a water-cooled connecting piece 17, which is designed as a contact sleeve and which at the same time serves to connect the electrical power supply.
  • the bottom electrode 7a is fastened to the end face of the connection piece 17 by means of a screw connection 23.
  • the bottom electrode 7a lies with its conical contact surfaces on the likewise conical inner contact surfaces of the contact sleeve, which widen towards the furnace bottom 3, whereby a good electrical connection and heat conduction between the two parts 7a and 17 is established.
  • Contact tabs 20 are arranged on the connecting piece 17 and are formed in one piece with the contact sleeve.
  • FIG. 1 shows part of the electrical power supply cable 22, which is connected by means of a screw connection 21 is connected to the contact tabs 20.
  • the connector 17 is provided with cooling channels 19 and with a cooling channel inlet connector 18.
  • a cooling liquid primarily water, is supplied to the cooling channels 19 through the inlet connection 18. It flows upwards through the cooling channels 19 of the connection piece 17 in a spiral arrangement and thus cools the bottom electrode 7a in an indirect manner.
  • the coolant outlet port of the connector 17 is on the same level as the inlet port 18 and is therefore not shown in Fig. 1.
  • the base electrode 7a is held by means of a fastening part, which consists of a metallic frustoconical shielding roof 24 and vertical holding crossbeams 24 ', the shielding roof 24 being arranged at least essentially centrally and open downwards with respect to the furnace axis and by means of the holding crossbeams 24' with the Oven vessel bottom 4 is firmly connected.
  • the bottom electrode 7a projects through the opening of the shielding roof and is supported on the contact sleeve, the connecting piece 17 being fastened to the underside of the shielding roof 24 by inserting an electrically insulating intermediate layer 27.
  • FIG. 2 shows a vertical section through the base electrode according to the invention in a first exemplary embodiment, according to FIG. 1, but in an enlarged representation.
  • the bottom electrode 7a with the diameter d in the region of the furnace vessel bottom 4 tapers conically up to the hearth surface 16 and has a diameter d 3 there.
  • the dashed line 10 ' indicates that the part 10 could also be cylindrical, without the pressing-out process of the base electrode from the furnace base 5 being thereby made significantly more difficult.
  • the average diameter of the bottom electrode 7a is denoted by d 2 and the total length of the bottom electrode 7a by l.
  • the bottom electrode 7b has a cylindrical shape and is likewise encased with the additional part 10, which in turn widens in the direction of the interior of the vessel. In this way, the pressing out of the bottom electrode 7b from the bottom of the furnace vessel is in turn made considerably easier.
  • the bottom electrode 7b - as can be seen from the dashed line - has a shaped body 15 made of a refractory material, which is arranged in a funnel-shaped recess within the bottom electrode 7b is, the recess extending from the end face of the bottom electrode 7b facing the interior of the vessel in the axial direction to the region of the furnace bottom 4.
  • the shaped body 15 is used for the purpose of reducing the cross section of the bottom electrode 7b in the direction of the interior of the furnace, the ratio of the cross section of the bottom electrode 7a, b, c, d in the bottom 4 of the furnace to the cross section in the furnace surface 16 being chosen to be at least 1.4: 1, preferably 2: 1 has been.
  • the liquid / solid boundary layer between the molten bath 13 and the end face of the bottom electrode 7a, b, c, d in the furnace hearth surface can be kept very stable and the service life of the bottom electrode 7a, b, c, d and the refractory lining 4 'of the furnace vessel bottom in the area near the electrode be significantly increased.
  • the power loss of the bottom electrode 7a, b, c, d can be reduced to a minimum.
  • the mean cross-section results from the arithmetic mean of the cross-section of the bottom electrode 7a, b, c, d in the region of the furnace bottom 4 and the cross-section in the furnace surface 16.
  • the electrode 7b has a diameter of d 1 , which is reduced by the shaped body 15 in the furnace hearth surface 16 to the radial ring width d 5 .
  • the electrode 7b, together with the part 10 which complements it, has a diameter d 7 in the furnace hearth surface 16.
  • the mean diameter is denoted by d 6 and the length is again denoted by e.
  • FIG. 4 shows the bottom electrode 7c, the outer diameter of which widens towards the interior of the vessel or at most remains the same, as indicated by the dashed lines 7c '.
  • the bottom electrode 7c has no addition of the part because the squeezing out to the inside of the vessel is guaranteed even without it.
  • the bottom electrode 7c is provided with a funnel-shaped shaped body 15 which, as already explained in the description of FIG. 3, stabilizes the liquid / solid boundary layer between the molten bath 13 and the end face of the bottom electrode 7a, b, c, d and Power loss limitation.
  • the bottom electrode 7c has a diameter d 1 in the furnace vessel bottom 4, an outer diameter d 8 ' in the furnace hearth surface 16, but only a metallic ring width d 10 in the furnace hearth surface 16.
  • the mean diameter is denoted by d 9 , the length in turn by l.
  • FIG. 5 shows a two-substance base electrode 7d, which consists of an iron alloy part 31 facing the furnace hearth surface 16 and the copper part 32. Both parts 31, 32 are metallurgically connected to one another, with the electrode 7b being pressed out from the outside in the direction of the interior of the vessel.
  • bottom electrodes 7a, b, c the cross-section of which in the oven hearth surface 16 tapers in relation to the oven vessel bottom 4, specifically in accordance with the dimensioning ratio according to the invention, the temperature gradient in the section 30 of the bottom electrodes 7a, b, c near the hearth surface can be increased . It is thereby achieved that the position of the liquid / solid boundary layer between the melt pool 13 and the end face of the bottom electrodes 7a, b, c can largely be located in the furnace hearth area 16. The bottom electrode 7a, b, c is not melted off and its service life is significantly increased. In addition, this measure ensures that the bottom electrode 7a, b, c can be better dimensioned for minimal power loss.
  • the temperature fluctuations of the bottom electrodes 7a, b, c which result from the states with and without current flow, are closer to the temperature of the refractory lining of the furnace vessel bottom 4 surrounding the bottom electrodes 7a, b, c.
  • FIG. 7 finally shows the temperature profile of a two-substance base electrode according to FIG. 5, but with a cross section that slightly decreases inwards.
  • I again indicates the temperature of the bottom electrode 7d in the furnace hearth surface 16, and A the temperature in the cooled section.
  • This reduction in cross section is achieved by attaching a shaped body 15 within the bottom electrode 7d. This molded body 15 was not shown in FIG. 5.
  • G 1 shows the temperature profile of the part made of iron alloy
  • G 2 that of the part made of copper
  • H represents the temperature of the refractory lining 4 'of the furnace bottom 4.
  • the temperature profile G 1 and G 2 approximates the temperature profile H. This shows the effect of the poorly thermally conductive iron alloy, despite the relatively large cross-section.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Discharge Heating (AREA)
EP84108020A 1983-07-28 1984-07-09 Electrode de fond pour four à arc à courant continu Expired EP0133926B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84108020T ATE27059T1 (de) 1983-07-28 1984-07-09 Bodenelektrode fuer einen gleichstromlichtbogenofen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH4134/83 1983-07-28
CH413483 1983-07-28

Publications (2)

Publication Number Publication Date
EP0133926A1 true EP0133926A1 (fr) 1985-03-13
EP0133926B1 EP0133926B1 (fr) 1987-05-06

Family

ID=4270470

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84108020A Expired EP0133926B1 (fr) 1983-07-28 1984-07-09 Electrode de fond pour four à arc à courant continu

Country Status (4)

Country Link
EP (1) EP0133926B1 (fr)
AT (1) ATE27059T1 (fr)
DE (1) DE3463568D1 (fr)
IN (1) IN163928B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0133931B1 (fr) * 1983-07-28 1987-01-07 BBC Brown Boveri AG Dispositif de refroidissement d'une électrode de fond d'un four à arc à courant continu
EP0133652B1 (fr) * 1983-07-28 1987-01-21 BBC Aktiengesellschaft Brown, Boveri & Cie. Dispositif de protection pour une électrode de fond d'un four à arc à courant continu
DE3535692A1 (de) * 1985-10-05 1987-04-09 Gutehoffnungshuette Man Kontaktelektroden-anordnung fuer gleichstrom-lichtbogen- oder widerstands-schmelzoefen
DE3535690A1 (de) * 1985-10-05 1987-04-09 Gutehoffnungshuette Man Kontaktelektrodenanordnung fuer gleichstrom-lichtbogen- oder widerstands-schmelzofen
CN106091702A (zh) * 2016-06-13 2016-11-09 巴涌 一种大炉底电能强度矿热炉

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103727799B (zh) * 2013-12-14 2016-02-24 云南新立有色金属有限公司 一种大型直流电弧炉连续冶炼高钛渣电极添加装置的使用方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE290945C (fr) *
US3671655A (en) * 1969-12-25 1972-06-20 Daido Steel Co Ltd Electrical transfer type plasma arc melting furnace
US3717713A (en) * 1971-02-18 1973-02-20 M Schlienger Arc furnace crucible
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
EP0058817A1 (fr) * 1981-02-24 1982-09-01 Man Gutehoffnungshütte Gmbh Arrangement d'électrode de contact pour four à arc ou four de fusion par résistance

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE290945C (fr) *
US3671655A (en) * 1969-12-25 1972-06-20 Daido Steel Co Ltd Electrical transfer type plasma arc melting furnace
US3717713A (en) * 1971-02-18 1973-02-20 M Schlienger Arc furnace crucible
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
EP0058817A1 (fr) * 1981-02-24 1982-09-01 Man Gutehoffnungshütte Gmbh Arrangement d'électrode de contact pour four à arc ou four de fusion par résistance

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0133931B1 (fr) * 1983-07-28 1987-01-07 BBC Brown Boveri AG Dispositif de refroidissement d'une électrode de fond d'un four à arc à courant continu
EP0133652B1 (fr) * 1983-07-28 1987-01-21 BBC Aktiengesellschaft Brown, Boveri & Cie. Dispositif de protection pour une électrode de fond d'un four à arc à courant continu
DE3535692A1 (de) * 1985-10-05 1987-04-09 Gutehoffnungshuette Man Kontaktelektroden-anordnung fuer gleichstrom-lichtbogen- oder widerstands-schmelzoefen
DE3535690A1 (de) * 1985-10-05 1987-04-09 Gutehoffnungshuette Man Kontaktelektrodenanordnung fuer gleichstrom-lichtbogen- oder widerstands-schmelzofen
CN106091702A (zh) * 2016-06-13 2016-11-09 巴涌 一种大炉底电能强度矿热炉

Also Published As

Publication number Publication date
ATE27059T1 (de) 1987-05-15
IN163928B (fr) 1988-12-10
EP0133926B1 (fr) 1987-05-06
DE3463568D1 (en) 1987-06-11

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