EP2250455A1

EP2250455A1 - Electric arc furnace

Info

Publication number: EP2250455A1
Application number: EP09717629A
Authority: EP
Inventors: Gerhard Fuchs; Joachim Ehle
Original assignee: Fuchs Technology AG
Current assignee: FUCHS TECHNOLOGY HOLDING AG
Priority date: 2008-03-03
Filing date: 2009-02-27
Publication date: 2010-11-17
Also published as: WO2009109335A1; DE102008012280A1; WO2009109335A8

Abstract

In an electric arc furnace, in which the electrode lift device (22, 23, 24) and the cover lift device (6) are disposed so that the cover lift (DH) and electrode lift (EH) add up, the weight load of the cover lift device is reduced by the electrode support device and the design of electrode and cover support framework are simplified, in that the electrode lift device (22, 23, 24) is supported on a girder (25), which is connected to the cover support arm, and the guides (26/1, 26/2; 27/1, 27/2; 28/1, 28/2) of the electrode lift columns (19, 20, 21) are fastened in a frame (14), which is fastened on the pivot gantry (11).

Description

Arc furnace

The invention relates to an electric arc furnace according to the preamble of claim 1.

In conventional electric arc furnaces, two or three charging operations are required to obtain the tapping weight of the arc furnace, that is, the weight of molten liquid metal at which the furnace is tapped. This means that the melting process has to be interrupted at least once, the furnace vessel lid has to be removed and the feedstock of another scrap basket has to be charged. This causes losses and an extension of the tap-to-tap time.

The volume of the charge material to be charged depends on its volume weight. If light scrap (metal chips) is to be melted down, a larger volume is required to achieve the tapping weight of the melt than for heavy scrap.

Through the document TRENKLER H: "ENERGY-SAVING DC TWIN SHELL ARC FURNA- CE FOR MELTING LOW-GRADE SCRAP" ABB REVIEW, ABB ASEA BROWN BOVERI, ZURICH, CH, No. 9/10, 1996, pages 18-27, XP000681512 , ISSN: 1013-3119, an energy-optimized DC furnace has become known in which only one charging process is required to achieve the tapping weight (single-drum charging) .This is achieved by increasing the volume of the furnace vessels To achieve the Abstichgewichtes the melting process must be interrupted by at least one additional charging process, increases the vessel height.

In the described furnace, the upper part of the vessel reaches a height of 6.5 m above the furnace platform and the greater height results in an electrode stroke of 8.5 m. Although this height and the resulting increase in the total volume of the furnace allows a Einkorbchargierung of light scrap of a density of about 0.6 t / m ³ , there are with the technical realization of the larger overall height and the increased electrode stroke but also connected large technical problems. In order to avoid a large moment in the described DC arc furnace in which the electrode support device is supported on the furnace platform, the electrode support arm made of aluminum and carried self-supporting.

In three-phase arc furnaces with three electrodes, in which the electrode support device is supported directly or via a pivoting portal on the furnace platform (DE 35 22 559 C1, DE 12 16 900 B, DE 198 23 226 A1, EP 0 203 339 B1) Because of the Lorentz forces acting on the electrodes, additional problems occur in the vessel height. If the length of the electrodes exceeds 3 to 3.5 m, then due to the Lorentz forces, electrode fractures may occur which necessitate an interruption of the melting process. The electrode length is limited. Since, in particular during the fine-tuning process, the electrodes have to be immersed until the arc burns on the bath surface, the limited permissible length of the electrodes also limits the height of the furnace vessel, if this can not be changed, as in the case of the known furnace.

The water-cooled panels of the cylindrical upper vessel part are divided in the known furnace in the direction of the cylinder axis into two sections. As a result, inter alia, a greater flexibility in operating the furnace is achieved, for example, when changing the charging material, the larger furnace volume is not justified.

From DE-B-1 433 424 a multi-furnace melting plant has become known, which contains an electric arc furnace with a furnace vessel for receiving the starting material to be melted, in particular metal scrap, and a furnace vault of the arc furnace mounted furnace vessel lid. A rotatable lifting cylinder arranged laterally of the furnace vessel serves, except for pivoting a pivoting arm supporting the furnace vessel lid, to set down the lid together with the pivoting arm and the electrodes, including their carrying device, on the furnace vault. For this purpose, the swivel arm is pivoted with the electrodes and the lid over the oven and placed the lid over the opening of the vault and the electrodes are moved into the oven vessel.

In this melting plant, as in the case of the electric arc furnace according to EP 0 039 023 A1, the entire electrode support device is carried by the cover support arm or the supporting structure of the cover. Since the cover support arm (referred to as swivel arm) carries the entire supporting device of the electrodes, the electrodes including the electrode lifting columns and electrode lifting devices are also lifted when the cover is lifted by the cover support arm, ie the cover lifting device and the electrode lifting device are arranged in series, so that electrode lifting and add lid lift. As a result, the stroke of the electrode lifting device can be reduced by the size of the cover stroke compared to an electrode support device arranged on the furnace platform. However, the Deckeltragarm carrying the entire electrode support device (swivel organ) is just as stable auszubil- as the Deckeltragarm lifting and lowering Deckelhubvorrichtung due to the large weight load and thus increases the Elektrodenhubes, as required for a furnace of the aforementioned type with Einkorbchargierung , a border.

The object of the invention is, in an electric arc furnace according to the preamble of patent claim 1, are arranged in the electrode lifting and Deckelhubvorrichtung that lid lift and electrode stroke add, the weight load of Deckelhubvorrich- device by the electrode support device to reduce and the construction of electrode and To simplify the cover structure.

This object is achieved by the electric arc furnace according to claim 1. Advantageous embodiments of the arc furnace according to the invention are specified in the subclaims.

While in known arc furnaces, the entire electrode support device is supported either directly or via a pivoting portal on the furnace platform (no addition of top lift and electrode stroke) or in its entirety is carried by the liftable and lowerable arm of the cover (addition of top lift and electrode stroke) is in the invention, the electrode support device is divided into two construction parts, one of which, namely the electrode lifting column lifting the electrode, is connected to the cover support arm and the other construction part, namely the guide, is supported on the pivoting portal.

In the electric arc furnace according to the invention, in which the electrode lifting columns can be shortened due to the series arrangement of the lid lifting device and the electrode lifting device, it is particularly advantageous if the edge of the oven vessel lid comprises a cylindrical portion which overlaps the cylindrical upper vessel part and which is displaced by the lid lifting device relative to the cylindrical upper one Vessel part is formed telescopically displaceable. at Such an electric arc furnace is increased in relation to the total stroke of the lid lift by the height of the cross-cylindrical portion and it can also be used by lowering the lid during the melting process shorter electrodes.

The invention will be explained in more detail by an embodiment with reference to seven figures. Show it:

1 is a schematic representation of a perspective view of a furnace installation with an electric arc furnace, the electrodes of which are partially retracted into the vessel; FIG. 2 is a plan view of the electric arc furnace including its cover and electrode support devices;

3 is a side view of the furnace plant of Fig. 1,

4 is a view of the arc furnace from the rear corresponding to the section IV-IV of Fig. 3, Figure 5 is the section V-V of Figure 2 with a detail showing the arrangement of a Deckelhubzylinders.

6 shows the section VI-VI of Fig. 2nd

7 is an enlarged view of the view of Figure 2 in the sectional plane of the upper roller guides the Elektrodenhubsäulen (section VII-VII of Fig. 5), and Fig. 8 a of FIG. 3 corresponding side view of a furnace, in which the embodiment of Swing portal is modified.

In Fig. 1, a part of a furnace system with a tiltable electric arc furnace 1 and a pan car 32 is shown schematically in perspective view. 33 denotes a transformer wall.

The arc furnace 1 contains, as is apparent in particular from the sectional representation according to FIG. 5 - here the section along the line VV of FIG. 1 or FIG. 2 is shown - a furnace vessel 2 from a lower vessel part 2 receiving the molten metal / 1 and a cylindrical upper part of the vessel 2/2. On the furnace vessel, a furnace vessel cover 3 with passage openings for arc electrodes 4 (FIGS. 1 to 3) and an exhaust manifold 5 indicated by dashed lines is arranged. At the edge of the oven vessel lid 3, a cylindrical section 3/1 extending above the cylindrical upper vessel part 2/2 is mounted so that this cylindrical section 3/1 is lifted and lowered during the raising and lowering of the vessel vessel lid 3 relative to the cylindrical upper vessel. Part 2/2 telescopically displaceable (older, after the filing date present application published DE 10 2006 941 421 Al).

The Ofengefaßdeckel 3 is supported by a, by a Deckelhubvorrichtung 6 (Fig. 6) liftable and lowerable Deckeltragarm 7 (Fig. 5 and 2), which engages with two legs 7/1 and 7/2 the lid 3 fork-shaped and over at the edge the lid attached pin carries the oven vessel lid.

The Deckeltragarm 7 is mounted on two spaced apart Deckelhubsäulen 8/1 and 8/2 (see Fig. 4, 5 and 7), synchronously lifted and lowered by a respective hydraulic cylinder 9/1 and 9/2 of the Deckelhubvorrichtung 6 are.

As particularly shown in FIGS. 5 and 6, the two hydraulic cylinders 9/1 and 9/2 are articulated on a first cross member 10, which is fastened on a pivoting portal 11 arranged on the side of the furnace vessel. The pivoting portal 11 is configured in a known manner and pivotable about a stationary pivot pin 12 whose axis is parallel to the furnace vessel axis in order to pivot the lifted by the Deckelhubvorrichtung furnace vessel lid and in the illustrated case, the electrode support device for a charging process to the side. In the illustrated case, the swivel portal 11 on a chassis that runs guided by the pivot pin 12 on a circular rail 13. Other known configurations of a pivoting portal can also be used, such as the modification shown in FIG. 8.

The mounted on the swivel portal first cross member 10, which is formed in the embodiment as a rectangular profile support is part of a mounted on the swivel portal frame 11 14, in which the guides 15/1 and 15/2 for the Deckelhubsäulen 8/1 and 8 respectively / 2 (see Figs. 4 and 5) are attached. The guides 15/1 and 15/2 are respectively arranged in an upper and in a lower plane and usually designed as roller guides. In the embodiment, as shown in Fig. 7 with reference to the roller guides for Elektrodenhubsäulen shown, V-shaped arranged rollers used, run on which strips of the lifting columns. Such guides are known and are therefore not explained in detail.

The illustrated electric arc furnace is a three-phase furnace having three electrodes 4 which are respectively clamped in electrode support arms 16, 17 and 18, respectively. The electrode support arms 16, 17 and 18, respectively are each mounted on the electrode lifting columns 19, 20 and 21, which are independently raised and lowered by trained as a hydraulic cylinder Elektrodenhubvorrichrungen 22, 23 and 24 respectively. The lifting cylinders are articulated on a second cross member 25, which is connected to the Deckelhubsäulen 8/1 and 8/2 and thus together with the Ofengefäßde- disgust by the Deckelhubvorrichtung can be raised or lowered. By means of the cross member 25 connected to the cover lifting columns, the strokes are added when the lifting devices for the cover and the electrodes are actuated.

The Elektrodenhubsäulen 19, 20 and 21 are as well as the Deckelhubsäulen 8/1, 8/2 guided by guides 26/1, 27/1 and 28/1, which are fixed in a second upper level of the frame 14, and by Guides 26/2, 27/2 and 28/2, which are fixed in a second lower level of the frame 14. The movable cross member 25 and the Deckelhubzylinder 9/1, 9/2 are thus not burdened by the weight of the guides for the Elektrodenhubsäulen. As is apparent from the sectional view of FIG. 7, the guides are designed as roller guides in which the electrode lifting columns 19, 29 and 21 provided with guide edges are guided.

In FIG. 6, the lid lift DH and the electrode stroke EH are indicated at respectively extended lift cylinders 6 and 22, 23 and 24, respectively. It can be seen that the cover stroke DH and the electrode stroke EH add up to a possible total stroke of the electrode support arms 16, 17 and 18 and thus also of the clamped electrodes 4. In the above-described electric arc furnace according to DE-B1 433 424, the furnace vessel lid is as usual with the edge on the furnace vessel, so that a very small lid stroke is sufficient to pivot the lid freely to the side can. The addition of the lid lift and the electrode stroke thus only brings a slightly greater total lift than the electrode stroke alone. Of particular importance is the invention, if, as in the described arc furnace the furnace vessel lid 3, a cylindrical upper vessel part 2/2 cross-cylindrical section 3/1, which is formed by the Deckelhubvorrichtung 6 relative to the cylindrical upper vessel part 2/2 telescopically displaceable , An arc furnace with such a configuration of the furnace vessel lid allows Einkorbchargierung, as in the energy-optimized DC furnace described above and at the same time a shortening of the electrode length, so that the Einkorbchargierung can also be realized in three-phase furnaces. Because of the cylindrical section 3/1, the lid lift DH is increased by at least the height of the cylindrical section 3/1, so that the lid on the one hand placed on the edge of the oven and on the other hand can be raised so far that a lateral pivoting is possible.

In the illustrated electric arc furnace, a hydraulic support cylinder 30 is mounted on the opposite side of the Deckelhubsaulen on the vessel wall, on which a stop attached to the cylindrical portion 3/1 of the cover 31 can be supported. This measure serves to support the attached to the legs 7/1, 7/2 of Deckeltragarms 7 cover 3 during melting support to avoid impossible pitching of the furnace portal. It can be attached to the lid circumference a plurality of support cylinders 30. The piston (s) of the support cylinder (s) 30 are lowered synchronously with the cover during the melting process. The stroke is shortened relative to the stroke of the lid lifting cylinders 8/1, 8/2 in order to avoid collisions with the piston rods of the support cylinders 30 when the lid is pivoted in the raised position.

Fig. 8 shows an electric arc furnace in which, compared to the above-described with reference to FIGS. 1 to 7 arc furnace, the design of the pivoting portal is modified. Fig. 8 is a side view corresponding to Fig. 3 of the furnace.

While in the swivel gantry 11 of the light arc furnace described above with reference to FIGS. 1 to 7, the frame 14 in which the guides 26/1, 26/2; 27/1, 27/2: 28/1, 28/2 of the electric denhubsäulen 19, 20, 21 are supported on a chassis which, guided by a stationary pivot pin 12, on a circular rail 13 of the foundation runs ( FIG. 1), the frame 14 is supported on the platform 34 of the oven cradle of the tiltable arc furnace in the modified pivoting portal 11 'according to FIG. 8. For this purpose, an upper support structure 35 with an upper pivot 36 and below a lower support structure 37 with a lower pivot 38 is attached to the mitkippenden platform 34 of the furnace cradle above. The two pivots have a common axis 39 which, like the axis of the pivot 12 of the embodiment of FIG. 3, is parallel to the central axis of the furnace vessel. The pivot pins 36 and 38 are used during pivoting of the pivoting portal 1 1 'by means of a pivoting device, not shown, as a guide, as well as in the embodiment of FIG. 3, the pivot pin 12 for the pivoting portal 1 1. On the frame 14, an upper support member 40 is attached above having a support pivot bearing 41, with which the upper support member 40 rotatably supported on the upper pivot 36. In addition, at the bottom of the frame 14 or at the frame with the frame 14 fixedly connected cross member 10, a lower support member 42 is fixed, which is rotatably connected by a lower pivot bearing 43 with the lower pivot 38.

Claims

claims

1. electric arc furnace (1) comprising a furnace vessel (2) from a lower vessel part (2/1) and a cylindrical upper vessel part (2/2) for receiving feedstock to be melted, in particular of scrap metal, a furnace vessel lid (3) of a lid support arm (7) which can be lifted and lowered by a lid lifting device (6), a pivoting portal (11, 11 ') arranged laterally of the oven vessel (2), which carries the lid lifting device (6) and which is parallel to the central axis of the oven vessel (2) aligned pivot axis (39) is pivotable, at least one electrode support arm (16, 17, 18) for clamping an arc electrode (4) at one, parallel to the central axis of the furnace vessel (2) by guides (26/1, 26 / 2; 27/1, 27/2: 28/1, 28/2), which is liftable and lowerable by an electrode lifting device (22, 23, 24) on a carrier connected to the cover support arm (7) he (25) is supported, characterized in that the guides (26/1, 26/2; 27/1, 27/2: 28/1, 28/2) of the electrode lifting column (19, 20, 21) are fastened in a frame (14) fastened on the pivoting portal (11, 11 ').

2. Electric arc furnace according to claim 1, characterized in that in the frame (14) in which the guides (26/1, 26/2, 27/1, 27/2: 28/1, 28/2) of the electrode lifting column ( 19,20,21) are fixed and the guides (15/1: 15/2) at least one Deckeltragarm (7) carrying the lid lifting column (8/1: 8/2) are attached.

3. electric arc furnace according to Anspruchl or 2, which is designed as a three-phase arc furnace with 3 electrodes, characterized in that in the on the swivel portal (1 1, 1 1 ') fixed frame (14), in a first upper and in a first lower level Guides (15/1: 15/2) are fixed for a first and for a second lid lift column (8/1: 8/2) and that in the space between the two lid lift column (8/1: 8/2) in a second upper one and in a second lower level guides (26/1, 26/2; 27/1, 27/2: 28/1, 28/2) are mounted for juxtaposed Elektrodenhubsäulen (19,20,21).

4. Electric arc furnace according to claim 3, characterized in that the Deckelhubvorrichtung (6) on a pivoting portal (1 1, 11 ') attached to the first cross member (10) is supported and a by the Deckelhubvorrichtung (6) liftable and lowerable second cross member (25) carries, on which the Elektrodenhubvorrichtungen (22,23,24) of the Elektrodenhubsäulen (19,20,21) are supported.

5. Electric arc furnace according to claim 4, characterized in that the Deckelhubvorrichtung (6) a first, under the first Deckelhubsäule (8/1) arranged hydraulic cylinder (9/1) and a second, under the second Deckelhubsäule (8/2) arranged hydraulic cylinder (9/2), and that the two hydraulic cylinders (9/1, 9/2) are supported on the first cross member (10) and support the second cross member (25).

6. Electric arc furnace according to claim 5, characterized in that the two cross members (10, 25) in the retracted position of the hydraulic cylinder (9/1, 9/2) are arranged adjacent to each other.

7. Electric arc furnace according to one of the preceding claims, characterized in that the edge of the furnace vessel lid (3) comprises a cylindrical upper vessel part (2/2) cross-cylindrical portion (3/1) by the Deckelhubvorrichtung (6) relative to the cylindrical upper vessel part (2/2) is formed telescopically displaceable.

8. Electric arc furnace according to one of the preceding claims, characterized in that the overlapping cylindrical edge portion (3/1) of the furnace vessel lid (3) by means of a stop (31) at its periphery by at least one support cylinder (30) can be supported.

9. electric arc furnace according to one of the preceding claims, characterized in that the pivoting portal (1 1) comprises a chassis which is guided by a pivot pin (12) on a circular rail (13).

10. Electric arc furnace according to one of claims 1 to 8, characterized in that the pivoting portal (H ') at the mitkippenden platform (34) of the oven cradle of a tiltable arc furnace via a top of the frame (14) attached upper support member (40) and rotatably supported at the bottom of the frame (14) fixed lower support member (42).

11. An electric arc furnace according to claim 10, characterized in that the upper support member (40) via a support rotary bearing (41) rotatably supported on an upper pivot (36), which at an ner mounted on top of the platform (34) of the oven cradle mounted upper support structure (35).

12. An electric arc furnace according to claim 1 1, characterized in that the lower support member (42) via a pivot bearing (43) rotatably supported on a lower pivot (38) on a bottom of the platform (34) of the oven cradle mounted lower support structure (37) is attached.