EP2883418B1 - Device and method for changing at least one electrode of a melt-metallurgical vessel - Google Patents

Description

The invention relates to a device and a method for changing at least one electrode of a melt metallurgical vessel, which has a receptacle for melt and for covering the receptacle a vessel lid with an opening per electrode, wherein the at least one electrode is positionable by means of at least one electrode holder and the vessel lid in that at least one electrode and the at least one electrode holder can furthermore be raised by means of a lifting and pivoting device and can be pivoted laterally about a vertical axis of rotation.

The rapid replacement of spent electrodes is essential for an energy-efficient and time-saving smelting process in a smelting metallurgical vessel, in particular an electric arc furnace, and is increasingly coming into focus with the ever-increasing performance requirements for smelting plants and the continuous increase in energy. Electrical energy is introduced into the molten material, usually in the form of metal scrap, via the electrodes, whereby the electrode material, which usually consists of graphite, is consumed.

Such a device is for example from the document US 4,345,333 known, wherein the melt metallurgical plant here comprises an electric arc furnace system with a liftable and pivotable furnace lid and one to two melt vessels. In addition to a melting vessel, alternatively between the two melting vessels, there is a cassette rotatable about its vertical center axis, which has cylindrical openings for receiving used electrodes and displaced therefrom further cylindrical openings for holding new electrodes. The cassette is here together with its central rotating mechanism and several below the cassette arranged and engaging in the cylindrical openings lifting cylinders for lowering the used electrode pieces and for lifting the new electrodes completely in the pivoting range of the furnace lid.

In the direct sphere of influence of a melt-metallurgical vessel, enormous corrosive influences act on movable mechanisms such as lifting cylinders and swivel joints, so that regular maintenance and / or replacement of components is unavoidable. It has been found that the maintenance of such devices known from the prior art for the replacement of electrodes must be carried out more frequently if movable mechanism is arranged directly in the pivoting region of the furnace lid or vessel lid. Particles like flaking solidified metal droplets, dust particles, etc. can fall down from the vessel lid, get into the moving mechanics and damage or block the mechanics.

In DE 20 50 418 A1 is a device for electro-melting of Abschmelzelektroden with multiple height-adjustable electrode support arms - which are pivotable in the horizontal direction - shown.

It is therefore an object of the invention to provide a low-maintenance device and a method suitable for operating such a device for changing at least one electrode of a melt-metallurgical vessel.

The object is for the device for changing at least one electrode of a melt metallurgical vessel, which has a receptacle for melt and to cover the receiving device a vessel lid with an opening per electrode, wherein the at least one electrode is positionable by means of at least one electrode holder and the vessel lid, the at least one electrode and the at least one electrode holder by means of a lifting and pivoting device liftable about a vertical axis of rotation are laterally pivoted, solved in that in addition to the receiving device at least two electrode changing stations are provided, which are arranged either side by side in a pivoting range of the lifting-pivoting device on a circular path around the axis of rotation or alternately into a Pivoting range of the hub pivoting device can be brought to the circular path about the axis of rotation.

In such a device no moving mechanisms in the pivoting range of the vessel lid are present, which require intensive maintenance.

If the at least two electrode change stations are arranged next to one another in a swivel range of the lifting / swiveling device on a circular path around the axis of rotation, then only the electrode (s) and the electrode holder move over them, optionally also the vessel lid. The electrode changing stations are fixed units that can be formed from simple mechanical holders. Maintenance is rarely, if not at all, necessary, and may, for example, be carried out simultaneously with necessary maintenance of the vessel lid.

If the electrode changing stations are alternately movable into the swivel range of the lifting / swiveling device on the circular path about the rotation axis, then the mechanism for this introduction of an electrode changing station into the swivel range is outside the swivel range itself and is thus deprived of increased particle load. Such an arrangement is also very low maintenance and also easily accessible to the maintenance personnel.

The tube lid itself is preferably not moved with the at least one electrode and the / the electrode holder (s) when changing electrodes. Optionally, the vessel lid can also be moved, since any movable mechanism of the device for changing at least one electrode is outside the pivoting range.

A molten metallurgical vessel with a device according to the invention has been proven, wherein the device comprises a movable mechanism which is arranged outside the pivoting range of the lifting-pivoting device and by means of which at least two electrode changing stations can be brought in alternation in the pivoting range of the lifting and pivoting device on the circular path about the axis of rotation.

The molten metallurgical vessel is preferably an electric arc furnace. While the electrode consumption in a conventional electric arc furnace is different for each electrode present due to the irregular scrap distribution and nature, the required drilling phase at which the electrodes drill into the scrap, and the arc length, etc. occurring, the electrodes consume one another melt metallurgical vessel with Flachbadbetrieb in which the arcs burn evenly on the bath surface, very evenly. Thus, in flat bath operation, a simultaneous replacement of all existing electrodes is generally to be expected.

The melt-metallurgical vessel may also be ladle furnaces or similar melt-metallurgical vessels operated with electrodes or self-consuming / consuming energy transfer devices.

It has proven useful if the at least two electrode changing stations of the device are identical. Particularly preferred is an education or at least lining both electrode changing stations from / with refractory material, so that hot remnants of electrodes can be safely parked in each electrode change station. A lining of an electrode changing station with in particular refractory elastic fiber material has been proven to reduce the mechanical stress on the remaining pieces of the electrode (s) when stopping and to damp their impact in the electrode changing station.

Alternatively, a lining may also be formed in the form of a refractory metallic clamping device, which lock the parked remnants.

It has proved to be advantageous for the device if a first electrode change station of the at least two electrode change stations forms a storage station for a remainder of the at least one electrode and if a second electrode change station of the at least two electrode change stations, a placement station for holding at least one spare electrode by means of at least one Electrode holder is receivable forms. In this way, the hot leftovers can initially remain in the storage station and cool down so far that their further processing is easily possible. A loss of time in the assembly of the electrode holder with the replacement electrodes does not arise because the replacement electrode (s) are provided by a further electrode exchange station.

Preferably, the first and the second electrode changing station of the device are arranged to alternately form the parking station and the loading station. Remaining pieces of electrodes remaining in an electrode changing station used as storage station can be directly mechanically connected to replacement electrodes and reused for the next required electrode change, the storage station now holding the next replacement electrode and thus now functioning as a placement station.

In a preferred embodiment of the device at least two, in particular three, electrodes are present and on the circular path between the receiving device and the at least two electrode exchange stations, a Nachsetzstation is arranged, the refractory horizontal plane for Längenmaßabgleich the at least two electrodes to a uniform length measure between the plane and having at least one electrode holder. Such a Nachsetzstation is particularly for a conventionally operated electric arc furnace, in which a different levels of erosion occurs at the existing electrodes, an advantage. But even in Flachbadbetrieb it may, although rarely required be to set the ends of the electrodes at the same height.

In a further preferred embodiment of the device, the at least two electrode changing stations are connected to a vertical exchange unit rotation axis, which is set up to pivot the electrode change stations horizontally into the pivoting range of the lifting and pivoting device. In this case, the exchange unit rotation axis itself is outside the pivoting range and thus protected from particles.

It has proven useful if at least one assembly unit for the mechanical connection of the remaining piece of the at least one electrode with at least one electrode extension piece is assigned to the at least two electrode changing stations of the device. This mounting unit may comprise a robot which automatically forms the mechanical connection between the respective remnant and an electrode extension piece, wherein still hot remnants can be reused. Alternatively, the assembly unit comprises a removal device for removing the respective remainder piece from the storage station in order to mechanically connect it manually to an electrode extension piece.

• Anheben und Schwenken des Reststücks der mindestens einen Elektrode und der mindestens einen Elektrodenhalterung, optional weiterhin des Gefäßdeckels, um die Drehachse in Richtung der mindestens zwei Elektrodenwechselstationen;
• Positionieren des Reststücks der mindestens einen Elektrode und einer ersten Elektrodenwechselstation der mindestens zwei Elektrodenwechselstationen zueinander und Abstellen des Reststücks aus der mindestens einen Elektrodenhalterung in die erste Elektrodenwechselstation, die als Abstellstation fungiert;

• Positionieren der mindestens einen Elektrodenhalterung und einer zweiten Elektrodenwechselstation der mindestens zwei Elektrodenwechselstationen zueinander und Bestücken der mindestens einen Elektrodenhalterung mit mindestens einer Ersatzelektrode, wobei die zweite Elektrodenwechselstation als Bestückungsstation fungiert;
• Schwenken und Absenken der mindestens einen Ersatzelektrode und der mindestens einen Elektrodenhalterung, optional weiterhin des Gefäßdeckels, um die Drehachse in Richtung der Aufnahmeeinrichtung;
• Entnahme des Reststücks aus der Abstellstation und/oder Herstellen einer mechanischen Verbindung zwischen dem Reststück der mindestens einen Elektrode und mindestens einem Elektrodenverlängerungsstück unter Ausbilden einer weiteren Ersatzelektrode; und
• Wiederholen des Verfahrens nach einer Zeitspanne Z.

The object is achieved for the method for changing at least one electrode of a melt-metallurgical vessel by means of a device according to the invention and with the following steps:

• Raising and pivoting the remainder of the at least one electrode and the at least one electrode holder, optionally further of the vessel lid, about the axis of rotation in the direction of the at least two electrode changing stations;
• Positioning the remainder piece of the at least one electrode and a first electrode exchange station of the at least two electrode changing stations to each other and placing the remainder piece out of the at least one electrode holder in the first electrode exchange station, which acts as a storage station;

• Positioning the at least one electrode holder and a second electrode change station of the at least two electrode change stations to each other and equipping the at least one electrode holder with at least one replacement electrode, wherein the second electrode change station acts as Bestückungsstation;
• Pivoting and lowering the at least one replacement electrode and the at least one electrode holder, optionally further of the vessel lid, about the axis of rotation in the direction of the receiving device;
• Removing the remaining piece from the storage station and / or establishing a mechanical connection between the remaining piece of the at least one electrode and at least one electrode extension piece to form a further replacement electrode; and
• Repeat the procedure after a period of time Z.

When repeating the method, the first electrode change station can again act as a stop station and the second electrode change station again as a loading station. Alternatively, however, the second electrode change station can also act as a storage station and the first electrode change station as a placement station. This is particularly preferred if the remaining pieces are already connected in the region of the electrode exchange station with electrode extension pieces. At each repetition of the process, the first and second electrode changing stations then act alternately as a stopping station.

The inventive method enables a fast, efficient and resource-saving operation of the device according to the invention, which minimizes interruptions in the melt operation due to their low maintenance requirements. Residual pieces of the electrode (s) are reused and finally applied completely.

When stopping remnants and picking up the replacement electrode (s), it is preferable if the electrode holder is lowered or raised as needed by means of the lifting and pivoting device.

It has proved to be advantageous if the first electrode exchange station is pivoted about the exchange unit rotation axis from a position within the pivoting range of the lifting and pivoting device to a position outside the pivoting range of the lifting and pivoting device and at the same time the second changeover electrode station around the exchange unit rotation axis of a position outside the pivoting range of the lifting-pivoting device is pivoted to a position within the pivoting range of the lifting-pivoting device. As already explained above for the device according to the invention, in this way the hot remaining pieces can initially remain in the storage station and cool down to the extent that their further processing is possible without any problem. A loss of time in the assembly of the electrode holder with the replacement electrodes does not arise because the replacement electrode (s) are provided by a further electrode exchange station. The arrangement of the exchange unit rotation axis outside the pivoting range of the Hub-Schwenkvorrichtung or the vessel lid has a favorable effect, i. extending to the maintenance cycles of the electrode changing stations.

In the case of an uneven consumption of a plurality of existing electrodes, lifting and pivoting of the unevenly long remaining pieces of the electrodes and of the at least one electrode holder around the axis of rotation preferably takes place in the direction of the set-up station arranged between the receiving device and the at least two electrode changing stations, wherein the at least one electrode holder is opposite the mounted electrodes is shifted such that the remnants are leveled with their at least one electrode holder remote ends on the horizontal plane of the Nachsetzstation and wherein subsequently pivoting and lowering the leveled electrodes and the at least one Electrode holder takes place about the axis of rotation in the direction of the receiving device. The plane thus serves to level or level the free ends of the electrodes, which in operation protrude through the vessel lid into the receptacle, to maintain a uniform melting operation.

FIGen 1 bis 3

schematisch einen Elektrolichtbogenofen mit einer ersten Vorrichtung von oben;

FIG 4

einen Teilschnitt durch den Elektrolichtbogenofen; und

FIG 5

schematisch einen Elektrolichtbogenofen mit einer zweiten Vorrichtung von oben.

The FIGS. 1 to 5 The invention is intended to exemplify devices according to the invention on melt-metallurgical vessels and methods for their operation. To show:

FIGS. 1 to 3

schematically an electric arc furnace with a first device from above;

FIG. 4

a partial section through the electric arc furnace; and

FIG. 5

schematically an electric arc furnace with a second device from above.

FIGS. 1 to 3 schematically show a melting metallurgical vessel 1 in the form of an electric arc furnace with a first device from above for changing the electrodes 4. The melt metallurgical vessel 1 comprises a receiving device 2 for melt (see also FIG FIG. 4 , which shows a partial section IV-IV through the electric arc furnace) and to cover the receiving device 2 a vessel lid 3, each with an opening 3a per electrode 4. In the receiving device 2 is to be smelted metal scrap 10. The electrodes 4 are each positioned by means of an electrode holder 5 , By means of a stroke-pivoting device 6, the electrodes 4 and the electrode holder 5, optionally further the vessel lid 3, can be raised and pivoted laterally about a vertical axis of rotation 6a.

In addition to the receiving device 2, two electrode changing stations 7, 7 'are present, which side by side in a swivel range S (cf. FIG. 3 ) of the stroke-pivoting device 6 are arranged on a circular path about the axis of rotation 6a. The electrode changing stations 7, 7 'each have three openings 7a, which can receive replacement electrodes or remnants of electrodes 4.

If the electrodes 4 are too short during operation of the electric arc furnace, the remaining pieces of the electrodes 4 are raised by means of the electrode holders 5 via the lifting pivot device 6 and pivoted in the direction of the electrode changing stations 7, 7 '. The remaining pieces 4a of the electrodes 4 are positioned above the first electrode exchange station 7, which functions as a storage station, and the electrode holders 5 are lowered and released. As a result, the still heated residual pieces 4a of the electrodes 4 slide into the openings 7a of the first electrode change station 7. The electrode holders 5 are raised and pivoted further in the direction of the second electrode changeover station 7 ', which here acts as a loading station and in whose openings 7a' replacement electrodes 4 ' are located. These are fixed in the electrode holders 5, the electrode holders 5 including the replacement electrodes 4 'are lifted and pivoted back to the container lid 3. After lowering the replacement electrodes 4 'through the openings 3a in the vessel lid 3, the melt-metallurgical process can be continued. The remaining pieces 4a are mounted on electrode extension pieces, so that further replacement electrodes are formed. This can be done in the region of the first electrode change station 7 or even after removal of the cooled residual pieces 4a thereof at a different location. These can now be kept, for example, in the first electrode change station 7, which acts as a placement station in a row. But also a renewed use of the second electrode change station 7 'as a placement station is possible.

If the replacement electrodes 4 'are also burnt down, the remnants are deposited in the area of the first or second electrode changeover station 7, 7' and the replacement electrodes are received in the region of the respective other electrode change station 7, 7 '.

The two electrode change stations 7, 7 'are fixedly installed in the first device shown in Figures 1 to 3 and have no moving parts, so that no intensive maintenance activities are necessary.

In the swivel area S between the receiving device 2 and the electrode changing stations 7, 7 'is optionally a Nachsetzstation 8. In Flachbadbetrieb can be dispensed with such a Nachsetzstation 8 mostly. If the electrodes 4 burn off unevenly and one or two electrodes 4 have shortened more than the remaining electrodes, then the free ends 40 of the electrodes 4 can be brought to the same level by means of the re-placement station 8. For this purpose, the electrode holders 5 are raised including the electrodes 4 and pivoted about the Nachsetzstation 8. The electrode holders 5 are lowered, each electrode 4 is released and placed on a horizontal plane of the Nachsetzstation 8. Now, the electrode holders 5 are again connected to the mutually leveled electrodes 4, lifted and pivoted about the vessel lid 3. After lowering the electrodes 4 through the openings 3a of the vessel lid 3, the melt-metallurgical process can be continued.

FIG. 5 schematically shows a melting metallurgical vessel 1 in the form of an electric arc furnace with a second device for changing the electrodes 4 from above. The same reference numerals as in FIGS. 1 to 4 designate the same elements. In addition to the receiving device 2, two electrode changing stations 7, 7 'are present here, which can be brought into the circular path about the axis of rotation 6a in alternation in the swiveling range S of the lifting swivel device 6. In this case, an exchange unit rotation axis 9 is present, around which the first electrode exchange station 7 and the second electrode exchange station 7 'are rotatable and can be introduced into the pivoting region S of the lifting and pivoting device 6 in alternation. Due to the arrangement of the movable mechanism of the exchange unit rotation axis 9 outside the pivoting range S, the second device very low maintenance and generally easily accessible.

The arrangement of the movable electrode changing stations is chosen here only by way of example and can readily be done in other ways, without departing from the spirit of the invention.

Claims (13)

1. Device for changing at least one electrode (4) of a melt-metallurgical vessel (1), which has a receiving device (2) for molten metal and a vessel cover (3) with one opening (3a) per electrode (4) for covering the receiving device (2), wherein the at least one electrode (4) is able to be positioned by means of at least one electrode support (5) and the at least one electrode (4) and the at least one electrode support (5), are able to be raised and pivoted laterally about a perpendicular axis of rotation (6a) by means of a lifting and pivoting device (6),
   characterised in that at least two electrode change stations (7, 7') are present next to the receiving device (2), which are either disposed next to one another in a pivot area (S) of the lifting and pivoting device (6) on a circular track about the axis of rotation (6a) or are able to be bought alternately into the pivot area (S) of the lifting and pivoting device (6) on the circular track about the axis of rotation (6a).
2. Device according to claim 1,
   characterised in that the vessel cover (3) is also able to be lifted by means of the lifting and pivoting device (6) and is able to be pivoted laterally about the vertical axis of rotation (6a).
3. Device according to claim 1 or 2,
   characterised in that the at least two electrode change stations (7, 7') are embodied identically.
4. Device according to one of claims 1 to 3,
   characterised in that a first electrode change station (7) of the at least two electrode change stations (7, 7') forms a storage station for a residual piece (4a) of the at least one electrode (4) and that at least a second electrode change station (7') of the at least two electrode change stations (7, 7') forms an equipping station for providing at least one replacement electrode (4'), which is able to be accepted by means of the at least one electrode support (5).
5. Device according to claim 4,
   characterised in that the first and the second electrode change station (7, 7') are configured to alternately form the storage station and the equipping station.
6. Device according to one of claims 1 to 5,
   characterised in that at least two electrodes (4) are present and that an adjustment station (8) is disposed on the circular track between the receiving device (2) and the at least two electrode change stations (7, 7'), which has a fireproof horizontal plane for equalising the longitudinal dimensions of the at least two electrodes (4) to a uniform longitudinal dimension between the plane and the at least one electrode support (5).
7. Device according to one of claims 1 to 6,
   characterised in that the at least two electrode change stations (7, 7') are connected to a perpendicular change unit axis of rotation (9) which is configured to pivot the electrode change stations (7, 7') horizontally into the pivot area (S) of the lifting and pivoting device (6) and on the circular track.
8. Device according to one of claims 1 to 7,
   characterised in that the at least two electrode change stations (7, 7') are assigned at least one installation unit for mechanical connection of the residual piece (4a) of the at least one electrode (4) with at least one electrode lengthening piece.
9. Method for changing at least one electrode (4) of a melt-metallurgical vessel (1) by means of the device according to one of claims 1 to 8, with the following steps:

   - Lifting and pivoting the residual piece (4a) of the at least one electrode (4) and of the at least one electrode support (5), optionally also of the vessel cover (3), about the axis of rotation (6a) in the direction of the at least two electrode change stations (7, 7');

   - Positioning the residual piece (4a) of the at least one electrode (4) and of a first electrode change station (7) of the at least two electrode change stations (7, 7') in relation to one another and storing the residual piece (4a) from the at least one electrode support (5) in the first electrode change station (7), which functions as a storage station;

   - Positioning the at least one electrode support (5) a second electrode change station (7') of the at least two electrode change stations (7, 7') in relation to one another and equipping the at least one electrode support (5) with a replacement electrode (4'), wherein the second electrode change station (7') functions as an equipping station;

   - Pivoting and lowering the at least one replacement electrode (4') and the at least one electrode support (5), optionally also the vessel cover (3), about the axis of rotation (6a) in the direction of the receiving device (2);

   - Removing the residual piece (4a) from the storage station and/or establishing a mechanical connection between the residual piece (4a) of the at least one electrode (4) und at least one electrode lengthening piece while forming a further replacement electrode; und

   - Repeating the method after a period of time Z.
10. Method according to claim 9,
    wherein during the repetition of the method the first electrode change station (7) and the second electrode change station (7') function alternately as storage station.
11. Method according to claim 9 or claim 10,
    wherein the first electrode change station (7) is pivoted about the change unit axis of rotation (9) from a position within the pivot area (S) of the lifting and pivoting device (6) into a position outside the pivot area (S) of the lifting and pivoting device (6) and that at the same time the second electrode change station (7') is pivoted about the change unit axis of rotation (9) from a position outside the pivot area (S) of the lifting and pivoting device (6) into a position within the pivot area (S) of the lifting and pivoting device (6).
12. Method according to one of claims 9 to 11,
    wherein, with an uneven consumption of a number of electrodes (4) a lifting and pivoting of the unequal-length residual pieces (4a) of the electrodes (4) and of the at least one electrode support (5) about the axis of rotation (6a) in the direction of the adjustment station (8) disposed between the receiving device (2) and the at least two electrode change stations (7, 7') is undertaken, wherein the at least one electrode support (5) is shifted in relation to the supported electrodes (4) such that the residual pieces (4a) with their ends (40) facing away from the at least one electrode support (5) are levelled on the horizontal plane of the adjustment station (8) and whereby subsequently a pivoting and lowering of the levelled electrodes (4) and of the at least one electrode support (5) about the axis of rotation (6a) in the direction of the receiving device (2) is undertaken.
13. Melt-metallurgical vessel (1), especially electric arc furnace, with a device according to one of claims 1 to 8, wherein the device includes a movable mechanism which is disposed outside the pivot area (S) of the lifting and pivoting device (6) and by means of which the at least two electrode change stations (7, 7') are able to be bought alternately into the pivot area (S) of the lifting and pivoting device (6) on the circular track about the axis of rotation (6a).

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