Melting vessel for an electric arc furnace, and electric arc furnace
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-16
- Publication Date
- 2026-03-25
AI Technical Summary
In electric arc furnaces, the use of steel melting vessels with electromagnetic stirring devices is hindered by magnetic interference and differing material expansion behaviors, leading to costly non-magnetic material requirements and installation challenges.
A melting vessel design featuring a metal side wall and bottom with a recessed non-magnetic cover plate, allowing for independent expansion and magnetic field transmission, using stops to maintain contact and prevent slipping, with the recess size optimized for the electromagnetic stirring device and vessel dimensions.
This design provides a cost-effective solution for enabling magnetic stirring while accommodating material expansion differences, ensuring efficient stirring and mechanical integrity without additional stress, and allowing for larger loads and improved static strength.
Smart Images
Figure EP2024063623_21112024_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Title of the invention Melting vessel for an electric arc furnace and electric arc furnace.
[0003] field of technology
[0004] The invention is in the field of steel production, specifically in the field of steel production using an electric arc furnace. The invention relates to a melting vessel, with a closed side wall and a melting vessel bottom with a bottom surface, for an electric arc furnace.
[0005] State of the art
[0006] In the production of steel in an electric arc furnace, steel bath movements are typically realized with Intergas purging plugs installed in the melting vessel.
[0007] A newer method for mixing the steel bath is an electromagnetic stirring device installed beneath the lower vessel. Since the lower vessel is typically made of steel, it would prevent the magnetic flux from the stirring coil to the melt. One possible, but very costly, solution is to construct the melting vessel from a non-magnetic material. Another option is to weld a non-magnetic material into a portion of the melting vessel. However, installing such a material is not easy, as it usually exhibits different material expansion behaviors across the temperature range encountered in an electric arc furnace.
[0008] CA2740528A1 shows an arrangement for attaching an electromagnetic stirrer to a vessel side wall of a vessel for holding liquid materials.
[0009] CN106170353A discloses a non-magnetic steel structure that enables the transmission of a magnetic field from an electromagnetic stirrer or a brake to the melt, which can be arranged, for example, in an electric arc furnace.
[0010] Summary of the invention
[0011] The object of the present invention is, on the one hand, to provide a cost-effective solution and, on the other hand, to enable the different expansion behavior of the materials used. This object is achieved by the side wall and a first partial region of the melting vessel base, which is connected to the closed side wall, being made of a metal, preferably steel with magnetic properties. A second partial region of the melting vessel base, which is enclosed by the first partial region, is designed as a recess. The recess depends on the size of an electromagnetic stirring device. The size of the electromagnetic stirring device depends on the size of the melting vessel and the stirring effect to be achieved on the melt.The recess is closed by a cover plate with non-magnetic properties, which has an overlapping contact surface that rests on the first partial area. The cover plate is mounted in a floating manner, and appropriately arranged stops ensure that the cover plate always has an overlapping contact surface over the entire circumference of the recess.
[0012] The cover plate typically exhibits a different expansion behavior than the metal from which the rest of the melting vessel base is made. This ensures that the cover plate can expand independently of the rest of the melting vessel base without introducing additional stress into the melting vessel base due to the cover plate's expansion behavior.
[0013] The stops ensure that the cover plate does not slip to the point where there is no longer any overlapping support surface. The stops can be welded-on metal plates that prevent further displacement in that direction once it reaches a side surface of the recess. However, it is also conceivable for the cover plate to be limited by the side wall in such a way that the cover plate always has an overlapping support surface when slipping. The size of the recess depends on the size of the electromagnetic stirring device to be used.
[0014] The recess has a projected area of at least 10% of the projected floor area. In most cases, the melting vessel floor is not a flat surface, which is why the projected area is used. The size depends on the dimensions of the electromagnetic stirring device and how the magnetic flux generated by the electromagnetic stirring device propagates.
[0015] A preferred embodiment provides that the recess has at least the size which corresponds at least to that projected area or substantially to that projected area which has a surface facing the recess of an electromagnetic actuator which can be arranged underneath, preferably an electromagnetic stirring device.
[0016] In a practical embodiment, the first partial area has a width over the entire circumference of at least 500 mm.
[0017] A particularly preferred variant provides that the stops are the side wall of the melting vessel, welded stops on the cover plate, a step in the melting vessel bottom and / or welded stops on the vessel bottom.
[0018] A practical design provides that the cover plate is made of one of the following materials: austenitic stainless steel, such as a steel with the material number 1.4828.
[0019] An advantageous embodiment provides that in the region of a tap opening, the cover plate in a maximum displaceable position has no overlap with the tap opening, preferably has at least a distance of 50 mm, particularly preferably has a distance of 100 mm.
[0020] The exact design of the tap hole depends on the shape of the recess. It's also conceivable that the cover plate has a slotted hole or a circular segment-shaped recess.
[0021] A preferred embodiment provides that the cover plate has stiffening plates on an underside which protrude through the recess.
[0022] It is conceivable that at least 3 stops are arranged, which also serve as stiffening plates.
[0023] Another preferred embodiment provides for the cover plate to be arched, spherical segment-shaped, or curved. These designs increase static strength, allowing greater loads to be absorbed than with a flat base. The arched design is such that the cover plate has, for example, a circular arc shape. The exact arc shape depends on the shape of the melting vessel base. The curved design has at least one bending edge and is bent such that the shape matches that of the melting vessel base.
[0024] A further advantageous embodiment provides for the melting vessel to have a refractory lining on the cover plate and the first section of the melting vessel bottom, and for the side wall to also have a refractory lining. The cover plate presses into the lining when expanded, allowing it to expand.
[0025] In a practical embodiment, the first sub-region of the melting vessel base is made from a single piece or by means of non-detachable connections. The first sub-region either consists of a single piece or is made by means of non-detachable connections, for example, welded joints. However, it is of course conceivable that add-on parts that are not necessary for the melting vessel base function are attached to the first sub-region of the melting vessel base by means of detachable connections.
[0026] In an advantageous embodiment, the cover plate is made from a single piece or using non-detachable connections. The cover plate either consists of a single piece or is manufactured using non-detachable connections, for example, welded joints. However, it is of course conceivable that add-on parts that are not necessary for the cover plate function are attached to the cover plate using detachable connections.
[0027] In a preferred embodiment, the recess has a projected area of at least 20%, preferably at least 30%, particularly preferably at least 40%, most particularly preferably at least 50% of a projected floor area.
[0028] In an advantageous embodiment, the cover plate is made of a non-magnetic metal, preferably non-magnetic steel.
[0029] The object is also achieved by an electric arc furnace comprising a melting vessel as described above and an electromagnetic stirring device arranged on the underside of the second part of the melting vessel. Brief description of the drawings
[0030] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of an embodiment, which is explained in more detail in conjunction with the drawings.
[0031] Fig. 1 - 4 schematic representations of different embodiments of a melting vessel
[0032] Fig. 5 - 8 schematic representations of an electric arc furnace with an embodiment of an inventive melting vessel.
[0033] Description of the embodiments
[0034] Fig. 1 shows an embodiment of a melting vessel 1 according to the invention. The melting vessel 1 consists of a closed side wall 3 and a melting vessel base 4, wherein the melting vessel base 4 consists of a first partial region 4b and a second partial region, wherein the second partial region is a recess 5. The recess 5 is closed by a cover plate 10. This cover plate 10 has non-magnetic properties so that an electromagnetic stirring device placed underneath can work as efficiently as possible and the stirring effect can reach the melt as unhindered as possible. The cover plate 10 has stops 11 which prevent the cover plate 10 from slipping so that it always has a contact surface on the melting vessel base 4 around its entire circumference. Furthermore, the stops 11 are intended to ensure that the cover plate 10 does not overlap with a tapping opening 2.The stops 11 can also be designed as stiffening plates so that the cover plate 10 meets the necessary mechanical requirements. Figure 1 shows a width B of the melting vessel base 4; this width B is at least 500 mm to provide sufficient support surface for the cover plate 10.
[0035] Fig. 2 shows a plan view of an embodiment of a melting vessel 1 according to the invention. The melting vessel 1 also has a recess 5, which is closed with a cover plate 10. The melting vessel 1 has a closed side wall 3, which has a lining 6. In a displaced position of the cover plate 10a, the side wall 3 serves as a stop, thus ensuring that the recess 5 always overlaps with the cover plate 10.
[0036] Figs. 3 and 4 show further embodiments of a melting vessel 1 according to the invention. The cover plate 10 has corresponding stops 11, which ensure that if the cover plate 10 slips, there is always an overlap between the recess 5 and the cover plate 10. The overlapping support surface 4a is clearly visible in Figs. 3 and 5. In Fig. 4, the stops 11 are attached to the melting vessel base 4.
[0037] Fig. 5 and Fig. 6 schematically illustrate an embodiment of an electric arc furnace with a melting vessel 1 and an electromagnetic stirring device 20. The electromagnetic stirring device 20 is arranged directly beneath the cover plate 10, which covers the recess 5. Fig. 5 also illustrates the lining 6, which is present both on the melting vessel bottom 4 and on the side wall 3. The recess 5 has at least a size corresponding to the projected area of the facing side 20a of the electromagnetic stirring device 20. A projected area of the facing side 20b of the electromagnetic stirring device 20 can, depending on the embodiment, be larger than the projected area of the recess 5.
[0038] Figs. 7 and 8 each show an embodiment of an electric arc furnace with a melting vessel base 4, which has a stepped shape in the first partial area 4b. The cover plate 10 is inserted into this stepped shape. This stepped shape can also serve as a stop. Furthermore, the cover plate 10 is designed to be arc-shaped or spherical segment-shaped.
[0039] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.
[0040] 1 melting vessel
[0041] 2 tap opening
[0042] 3 side wall
[0043] 4 Melting vessel bottom
[0044] 4a Support surface
[0045] 4b first section
[0046] 5 Recess
[0047] 6 Brick lining
[0048] 10, 10a cover plate
[0049] 11 attacks
[0050] 20 Electromagnetic stirring device
[0051] 20a Facing side
[0052] 20b Opposite side
[0053] B Width
Claims
Claims 1. Melting vessel (1) with a closed side wall (3) and a melting vessel bottom (4) with a bottom surface, for an electric arc furnace, characterized in that the side wall (3) and a first partial area (4b) of the melting vessel bottom which is connected to the closed side wall (3) is made of a metal, preferably steel with magnetic properties, and a second partial area of the melting vessel bottom (4), which is enclosed by the first partial area, is designed as a recess (5), the recess (5) is closed by a cover plate (10) which has non-magnetic properties, wherein the cover plate (10) has an overlapping support surface which rests on the first partial area, the cover plate (10) is mounted in a floating manner and correspondingly arranged stops (11) ensure that the cover plate (5) always has an overlapping support surface (4a) over the entire circumference of the recess (5), wherein the recess (5) has a projected area of at least 10% of a projected floor area.
2. Melting vessel (1) according to claim 1, characterized in that the recess has at least the size which corresponds at least to that projected area or substantially to that projected area which has a surface facing the recess of an electromagnetic actuator, preferably an electromagnetic stirring device, which can be arranged underneath.
3. Melting vessel (1) according to claim 1 or 2, characterized in that the first partial region has at least a width (B) over the entire circumference of at least 500 mm.
4. Melting vessel (1) according to claims 1 - 3, characterized in that the stops are the side wall of the melting vessel, welded stops (11) on the cover plate (10), a step in the melting vessel bottom (4) and / or welded stops (11) on the melting vessel bottom (4).
5. Melting vessel (1) according to claims 1 - 4, characterized in that the cover plate is made of an austenitic stainless steel.
6. Melting vessel (1) according to claims 1 - 5, characterized in that in the region of a tapping opening, there is no overlap with the tapping opening, preferably at least a distance of 50 mm from the tapping opening, particularly preferably a distance of 100 mm.
7. Melting vessel (1) according to claims 1 - 6, characterized in that the cover plate (5) has stiffening plates on its underside which protrude through the recess (5).
8. Melting vessel (1) according to claims 1 - 7, characterized in that the cover plate (5) is arc-shaped, spherical segment-shaped or curved.
9. Melting vessel (1) according to claims 1 - 8, characterized in that the melting vessel (1) has a refractory lining on the cover plate (5) and the first partial area of the melting vessel bottom (4) and the side wall (3) also has a refractory lining.
10. Melting vessel (1) according to one of claims 1-9, characterized in that the first partial region (4b) of the melting vessel bottom is made from one part or by means of non-detachable connections.
11. Melting vessel (1) according to one of claims 1-10, characterized in that the cover plate (10) is made from one part or by means of non-detachable connections.
12. Melting vessel (1) according to one of claims 1-11, characterized in that the recess (5) has a projected area of at least 20%, preferably at least 30%, particularly preferably at least 40%, most particularly preferably at least 50% of a projected bottom area.
13. Melting vessel (1) according to claims 1 - 12, characterized in that the cover plate (10) is made of a non-magnetic metal, preferably non-magnetic steel.
14. Electric arc furnace comprising a melting vessel according to claim 1 - 13 and an electromagnetic stirring device (20) arranged on the underside in the second partial region of the melting vessel (1).