WO2023016663A1 - Electromagnetic stirring apparatus for a metal furnace and method of operation thereof - Google Patents
Electromagnetic stirring apparatus for a metal furnace and method of operation thereof Download PDFInfo
- Publication number
- WO2023016663A1 WO2023016663A1 PCT/EP2021/072643 EP2021072643W WO2023016663A1 WO 2023016663 A1 WO2023016663 A1 WO 2023016663A1 EP 2021072643 W EP2021072643 W EP 2021072643W WO 2023016663 A1 WO2023016663 A1 WO 2023016663A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- windings
- electromagnetic stirring
- metal furnace
- furnace
- stirring
- Prior art date
Links
- 238000003756 stirring Methods 0.000 title claims abstract description 143
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 100
- 239000002184 metal Substances 0.000 title claims abstract description 100
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000004804 winding Methods 0.000 claims abstract description 117
- 239000000155 melt Substances 0.000 claims abstract description 60
- 230000005294 ferromagnetic effect Effects 0.000 claims abstract description 47
- 238000010891 electric arc Methods 0.000 claims description 22
- 230000005291 magnetic effect Effects 0.000 description 26
- 239000000463 material Substances 0.000 description 9
- 238000007670 refining Methods 0.000 description 9
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- 239000004411 aluminium Substances 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 6
- 239000010949 copper Substances 0.000 description 6
- 238000005265 energy consumption Methods 0.000 description 6
- 238000010079 rubber tapping Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 4
- 229910001021 Ferroalloy Inorganic materials 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 238000009847 ladle furnace Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910015136 FeMn Inorganic materials 0.000 description 2
- 229910002555 FeNi Inorganic materials 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 206010012289 Dementia Diseases 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
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
- F27D27/00—Stirring devices for molten material
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/5211—Manufacture of steel in electric furnaces in an alternating current [AC] electric arc furnace
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/5241—Manufacture of steel in electric furnaces in an inductively heated furnace
- C21C5/5247—Manufacture of steel in electric furnaces in an inductively heated furnace processing a moving metal stream while exposed to an electromagnetic field, e.g. in an electromagnetic counter current channel
-
- 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
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D2003/0034—Means for moving, conveying, transporting the charge in the furnace or in the charging facilities
- F27D2003/0083—Means for stirring the charge
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- Embodiments of the present disclosure relate to an electromagnetic stirring apparatus for a metal furnace, particularly for an electric arc furnace, and a method of operation thereof
- a melt may be stirred using an electromagnetic stirrer (EMS), fa general, a metal furnace is a vessel for metal processing.
- a metal furnace in the context of the present disclosure may include, but is not limited to, an electric arc furnace ( EA F ) for steelmaking, an electric arc furnace for ferro-alloy (for example, FeMn or FeNi) refining, a ladle furnace for steel refining, an aluminium melting furnace for scrap recycling, an aluminium holding furnace for alloying and casting, a copper anode furnace for copper refining, or a lead melting furnace.
- EA F electric arc furnace
- ferro-alloy for example, FeMn or FeNi
- Electromagnetic stirring is beneficial for many reasons. For example, electromagnetic stirring allows for improved melting speed and reduced process time, improx ed temperature homogenization, and reduced energy consumption of the metal furnace.
- the EMS is mounted below the hearth of the EAF) and the melt is stirred by the application of a magnetic field.
- a typical EMS has a linear design, comprising a linear core element with two or more windings wound thereon Electric currents arc applied to the w indings so as to generate a magnetic field in the linear direction along the length of the core element.
- Electric currents arc applied to the w indings so as to generate a magnetic field in the linear direction along the length of the core element.
- the resulting stirring of the melt is performed only in a linear direction.
- the melt when stirred linearly, encounters significant flow resistance when the flow reaches the walls of the hearth. Therefore, the electric energy consumption for stirring a melt using a linear EMS is high.
- the space available below the hearth of a metal furnace such as an EAF is typically limited, as the hearth is typically mounted on a large frame which allows for tilting of the EAF during tapping.
- the overall length of a linear EMS is limited by the space available in the frame.
- an electromagnetic stirring apparatus for a metal furnace includes a stirring assembly having a ferromagnetic core arranged in a ring-like configuration, and at least three windings which are wound on the ferromagnetic core such that a w inding tend of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration.
- the electromagnetic stirring apparatus further includes a multiphase AC power supply electrically connected to the at least three windings and a mounting member for mounting the stirring assembly below the metal furnace, wherein the multiphase AC power supply is configured for providing electrical currents to each of the at least three windings, the electrical currents being adapted for generating an electromagnetic stirring field for stirring a melt in the metal furnace when the stirring assembly is mounted below the metal furnace.
- a metal furnace includes an electromagnetic stirring apparatus according to the first aspect arranged below the furnace.
- a method for stirring a melt in a metal furnace includes providing a stirring assembly below the metal furnace, the stirring assembly having a ferromagnetic core arranged in a ring-like configurationand at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration.
- the method further includes providing electrical currents in each of the at least three windings, wherein the electrical currents are adapted for generating an electromagnetic stirring field for stirring the melt in the metal furnace when the stirring assembly is prov ided below the metal furnace.
- aspects of the present disclosure provide apparatus and methods for more energy efficient stirring of a melt in a metal furnace as compared to solutions known in the state of the art. Further, the improved apparatus of the present disclosure allows for increased flexibility and improved stirring of the melt, and allows for a more space efficient design suitable forapplications where space below the hearth of an EAF is restricted.
- Fig. 1 illustrates a schematic side view of an electric arc furnace having an electromagnetic stirring apparatus according to embodiments of the present invention
- Fig. 2a illustrates a schematic top view of an electric arc tanace having an electromagnetic stirring apparatus according to the current state of the art
- Fig. 2b illustrates a schematic top view of a melt flow in an electric arc tanace having an electromagnetic stirring apparatus according to the current state of the art
- Fig. 3 a illustrates a schematic top view of an electric arc tanace having an electromagnetic stirring apparatus according to embodiments of the present invention
- Fig. 3b illustrates a schematic top view of a melt flow in an electric arc furnace having an electromagnetic stirring apparatus according to embodiments of the present invention
- Fig. 4a-4d illustrate schematic top views of an electromagnetic stirring apparatus according to embodiments of the present invention
- Fig. 5 illustrates a schematic top view of an electromagnetic stirring apparatus according to embodiments of the present invention.
- Fig. 6 illustrates a schematic front view of an electric arc furnace having an electromagnetic stirring apparatus according to embodiments of the present invention.
- Fig. 1 shows an exemplary side section view of a metal furnace.
- the metal furnace as exemplarily shown in the figures is an electric arc furnace ( EAF ) 100, however the present disclosure is not limited thereto.
- the metal furnace may include any one of an electric arc furnace ( EAF) for steelmaking, an electric arc furnace for ferro-alloy (for example, FeMn or FeNi) refining, a ladle furnace for steel refining, an aluminium melting furnace for scrap recycling, an aluminium holding furnace for alloying and casting, a copper anode furnace for copper refining, a lead melting furnace, or any other suitable metal furnace known in the art.
- EAF electric arc furnace
- ferro-alloy for example, FeMn or FeNi
- a melt refers to a volume of material being processed in a metal furnace.
- the melt is a volume of material in a metal furnace which is to be stirred by an electromagnetic stirrer.
- the melt may refer to a volume of material which is completely molten, or may refer to a v olume of material w hich is partially molten and partially solid.
- the material may include a metal or a metal alloy
- the volume of material is an electrically conductive metal, or may include electrically conductive metal in at least a portion of the volume of material.
- the electric arc furnace 100 includes a hearth 101 having a bowl shape, particularly having an egg-shaped cross section when v iewed from above.
- the hearth 101 is lined w ith a refractory lining 102 and a working lining 103
- the working lining 103 may be a conductiv e lining, c.g a graphite lining.
- the hearth 101 contains the melt M. which is the material to be melted in the metal furnace
- Graphite electrodes 105 arc mov able mounted to the roof (not shown) of the electric arc furnace 100, and arc configured for generating one or more electric arcs to provide heat to the melt M.
- the EAF 100 exemplarily shown in the figures is an AC EAF which includes three electrodes 105.
- the electrodes 105 are configured to be movable in the vertical direction in order to control the arc generation as the electrodes 105 wear
- the electric arc furnace 100 max be configured for tapping or pouring the melt M
- the electric arc furnace 100 is mounted on a frame configured for tilting the electric arc furnace 100 m a tapping or pouring process
- ⁇ n eccentric bottom tap-hole (EBT) 104 is prov ided at one end of the hearth 101 for the melt M to flow from the hearth 101Arranged below the hearth 101 of the electric arc furnace 100 is an electromagnetic stirrer (EMS) 200, 300, 400, 500.
- EMS electromagnetic stirrer
- the EMS is configured to generate magnetic fields which penetrate the shell of the hearth 101 and the respectiv e linings 102, 103 and act on the melt M By applying magnetic fields, the meh M can be stirred so as to liquefy the material in the melt M faster more effectiv ely and with better temperature homogeneity
- the EMS typically includes an AC power supply, which may be mounted io the EMS or may be external to the LMS. to apply electrical currents and generate the magnetic fields.
- the electromagnetic stirrer provided beneath the hearth 101 is a linear EMS 200.
- a linear EMS 200 according to the current state of the art is exemplarily show in Fig, 2a.
- w hich show s a top v iew of a hearth 101 of a metal furnace.
- the metal furnace includes a linear EMS 200 arranged below the hearth 101.
- a typical linear EMS 200 includes a ferromagnetic core 201 and a plurality of windings 202a-f wound around the ferromagnetic core 201.
- a multiphase AC power supply provides electrical currents to each one of the plurality of windings 202a-f such that a magnetic field is generated and applied to the melt M inside the hearth 101 of the metal furnace.
- Fig. 2a further shows an exemplary shape of the hearth 101 and the location of the eccentric bottom tap-hole 104.
- the resulting flow pattern of the melt being stirred by the exemplary linear EMS 200 is illustrated in Fig. 2b. Since the magnetic field generated by the linear EMS 200 is only Ale to be applied to the melt M in a linear direction, the melt M can only be directed in a direction along the length of the linear EMS 200 and directly towards the wall of the hearth 101. When the melt flow impinges on the wall of the hearth 101, the flow changes direction to flow aroundand parallel to the wall of the hearth 101 . The melt flow encounters significant resistance when reaching the wall of the hearth 101. and the electric energy consumed by the linear EMS 200 to overcome the melt flow resistance is high.
- the dimensions of the linear EMS 200 may also be disadvantageous for implementing electromagnetic stirring on the metal furnace.
- a linear EMS 200 of the present state of fee art has a larger size to generate sufficient force to overcome the melt flow resistance, and challenges may arise when allocating space below the metal furnace due to the excessive length of the linear EMS 200 For example, it may be challenging to provide sufficient space for a linear EMS 200 in a support frame design for the metal furnace, particularly a metal furnace mounted on a support frame designed to be lilted during a tapping or pouring process.
- the present disclosure provides an EMS and methods for stirring a melt to solve the problems associated with the use of a linear EMS in metal furnaces.
- An EMS according to embodiments of the present disclosure offers reduced electric energy consumption, improved flexibility and more compact dimensions by implementing a ring-like configuration.
- An EMS according to the present disclosure is exemplarily shown in Fig. 3a.
- an electromagnetic stirring apparatus for a metal furnace including a stirring assembly having a ferromagnetic core arranged in a ring-like configuration and at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration.
- the electromagnetic stirring apparatus farther includes a multiphase AC powersupply electrically connected to the at least three windings and a mounting member for mounting the stirring assembly below the metal furnace (e.g. with the mounting member mechanically connected to the core and extending therefrom e.g.. upw ardly
- the stirring apparatus is used below the metal furnace, i.e, below the melt contained in the metal furnace.
- a metal furnace having a hearth and the electromagnetic stirring apparatus as described herein wherein the electromagnetic stirring apparatus is arranged bclov the furnace.
- the electromagnetic stirring apparatus is arranged below the heart of the metal furnace.
- the metal furnace may be any one of an electric arc furnace for ferro-alloy (for example, FcMn or FcNi ) refining, a ladle furnace for steel refining, an aluminium melting furnace for scrap recycling, an aluminium holding furnace for alloy inti and casting, a copper anode furnace for copper refining, a lead melting furnace.
- the metal furnace is an electric arc furnace.
- a method for stirring a melt in a metal furnace is provided.
- the method relates to stirring a melt in a metal fomace using the electromagnetic stirring apparatus described herein.
- the method includes providing a stirring assembly below the metal furnace, the stirring assemble having a ferromagnetic corearranged in a ring-like configuration and at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration.
- the method further includes providing electrical currents in each of the at least three windings, wherein the electrical currents are adapted for generating an electromagnetic stirring field for stirring the melt in the metal furnace when the stirring assembly is provided below the metal furnace.
- the method for stirring a melt in a metal furnace is provided, wherein the metal furnace is an electric are fomace.
- the electromagnetic stirring apparatus 300 includes a stirring assembly, which is arranged below the hearth 101 of the metal furnace.
- the stirring assembly includes the elements which are configured for generating magnetic fields w hich are used to stir the melt M.
- the stirring assembly includes a ferromagnetic core 301 arranged in a ring-like configuration, and at least three windings 302a-f wound on the ferromagnetic core. When a current is applied to the at least three windings 302a-f such that a phase difference exists between the currents in two or more windings, a magnetic field is generated for stirring the melt M.
- the EMS 300 exemplarily shown in Fig. 3a. six w indings 302a-f are provided. and the ferromagnetic core has a hexagonal ring-like configuration.
- the ferromagnetic core 301 of the stirring apparatus may include at least one core element arranged in a ring-like configuration.
- the ferromagnetic core may include a single element having a ring-like shape.
- the ferromagnrtic rare may include a single piece of ferromagnetic metal formed into a closed ring, for example, a toroid shape.
- a single core element may be impractical for a number of reasons, including challenging manufacturing and assembly of the windings 302a-f thereon.
- the ferromagnetic core 301 may include a plurality of core elements arranged in a ring-like configuration.
- a ferromagnetic core 301 may be formed by arranging a plurality of core elements each having a longitudinal shape into a ring-like configuration in the shape of a polygon.
- plurality of core elements may each have an arc shape which, when arranged in a ring-like configuration, form the shape of a circle.
- the plurality of core elements of the ferromagnetic core 301 may be arranged so that they join and abut each other at their respective ends, so that the ferromagnetic core 301 is a closed loop. Alternatively, the plurality of core elements may be arranged with a gap therebetween. In both cases, the ferromagnetic core 301 essentially forms an arrangement where the ferromagnetic core 301 is a magnetic loop, wherein the magnetic field within the ferromagnetic core 301 is a closed loop around the ring-like configuration.
- the term “ring-like configuration” refers to the overall shape of a ring.
- the ring-like configuration may be uniform or non-uniform.
- the ring-likc configuration refers to an arrangement of at least one object lying on a contour having a start point, where said contour circumscribes a circuit, and returns to an end point which is the same as the start point.
- the ring-like configuration may be an arrangement of objects lying on a ring-like contour, such as a circle, an oval or a polygon.
- the arrangement of objects on the contour may be continuous, for example, where the objects join or abut to one mother to form a closed circuit, or the arrangement of objects on the contour may be discontinuous, for example, where the objects have spaces therebetween.
- the ring-like configuration defines a circumferential direction, which is the direction along the contour of the ring-like configuration.
- the circumferential direction is the direction around the circle.
- the circumferential direction is the direction around the polygon.
- the w indings 302 a-f of the stirring apparatus arc arranged on the ferromagnetic core 301 such that a magnetic field is generated when electric currents are provided to two respective windings 302a-f
- Each respective winding 302a-f is wound on the ferromagnetic core 301 such that a winding axis of each respective winding 302a-f extends in a circumferential direction with respect to the ring-like configuration.
- the respective windings 302a-f are wound around the ferromagnetic core 301.
- the windings 302a-f are evenly spaced around the ring-like configuration in the circumferential direction.
- the axis is defined as a line extending tangential to the circumferential direction at a point around the contour of the ring-like configuration.
- the axis extending in the circumferential direction is a line extending tangential to the circle.
- the axis extending in the circumferential direction is a line extending coincident with a line segment of the polygon.
- the number of windings 302a-f is six.
- the minimum number of windings 302a-f to achieve appropriate stirring is three.
- the number of windings may also depend on the shape of the ring-like con figuration, and/or the number of core elements included in the ferromagnetic core 301.
- the number of windings 302a-f is at least six windings. More preferably the number of windings 302a-f is at least one winding per core element included in the ferromagnetic core 301.
- the resulting flow pattern of the melt being stirred by the EMS 300 according to the present disclosure is illustrated in Fig. 3b.
- the magnetic fields generated by the EMS 300 allow for a rotational flow of the melt M, such that the melt M is stirred around the hearth 101 instead of end-to-end as with a linear EMS.
- the melt M is not directed such that the melt flow impinges directly on the wall of the hearth 101.
- This rotational flow of the melt M exhibits si gni flcantl y lower flow resistance as compared to the end-to-end flow caused by a linear EMS.
- the strength of the magnetic field for stirring the melt M may be reduced, and consequently, the electric energy consumption of the EMS 300 is significantly reduced.
- the EMS 300 thus allows for improved stirring efficiency. Further still, due to the reduced strength of the magnetic field for stirring the melt M, the EMS 300 may be reduced in size as compared to a linear EMS, allowing for the EMS 300 to be more compact. Particularly, the EMS 300 may be easily adaptable to metal furnaces configured for tilting in a tapping or pouring process, which typically would have a sizeable mounting frame below the hearth 101 .
- Figs. 4A-4D exemplarily show electromagnetic stirrers 400-1, 400-22, 400-3, 400-4 according to embodiments of the present disclosure.
- the exemplary electromagnetic stirrers 400-1, 400-2, 400-3, 400-4 include different arrangements of ferromagnetic cores 301 and windings 302 arranged in different ring-like configurations.
- the electromagnetic stirring apparatus includes at least three core elements, wherein the at least three core elements have a longitudinal shape extending tangentially to the circumferential direction, and the ring-like configuration is preferably a polygonal configuration having at least three sides.
- Fig. 4 A exemplarily shows an EMS 400-1 having a ring-like configuration in the shape of a triangle.
- the ferromagnetic core includes three core elements 401a-c extending along the cireumferential direction of the ring-like configuration, and six windings 402a-f are wound thereon.
- Each of the three core elements 401 a-c are shown as having a gap therebetween, however the arrangement of the three core elements in a ring-like configuration forms a magnetic circuit through the ferromagnetic core.
- the exemplary EMS 400-1 has advantages in low complexity and a compact design suitable for smaller metal furnaces, or metal furnaces with restricted space beneath foe hearth.
- the triangular ring-type configuration may also be more suitable for stirring a melt in an egg-shaped hearth due to their similar shapes.
- Fig 4B exemplary show s an EMS 400-2 ha ⁇ ing a ring-type configuration in the shape ofa four- sided polygon, particularly a square.
- the four-sided polygon may instead be a rectangle or an irregular quadrilateral.
- the ferromagnetic core includes four core elements 401a-d arranged to form a magnetic circuit through the ferromagnetic core
- Such an EMS 400-2 may be suitable for maximising the use of av ailable space beneath metal furnaces having a mounting frame, as such a frame typically provides a rectangular-shaped area for the EMS.
- the EMS 400-2 includes two windings 302a-h per core element 301 a-d for a total of eight windings 302a-h. With a higher number of windings 302a-h, this configuration may allow for more flexibility in control, e.g, by allowing for more variety in winding pairings to be configured.
- Fig. 4C exemplarily shows an EMS 400-3 having a ring-type configuration in the shape of a six-sided polygon, particularly a hexagon.
- the ferromagnetic core includes six core elements 401a-fr and six windings 402a-f are wound thereon.
- a configuration having one winding per core element allows for largerw indings to bc installed, w hich may allow for a stronger magnetic field for stirring the melt.
- the two examples shown in Fig. 4B and 4C further allow for a space to be provided at the centre of the ring-like configuration . These designs may be advantageous for use in a DC EAF having a large electrode protruding from the botom of the hearth.
- the electromagnetic stirring apparatus includes at least tw o core elements, wherein the at least two core elements have an arc shape extending in the cireumferential direction, and the ringlike configuration is preferably a circular configuration or an oval configuration.
- Fig. 4D exemplarily shows an EMS 400-4 having a ring-type configuration in the shape of a circle.
- the ferromagnetic core includes a plurality of arc-shaped core elements 401a-f
- Arc-shaped core elements 401a-f may generate a more uniformly circular magnetic field, allowing for uniform circular stirring of the melt, which may be more efficient than an EMS having longitudinal-shaped core elements.
- the ends of each respective core element 401a-f are joined and aubbed to each other, forming a closed loop ferromagnetic core. Abuting the core elements may improve the strength of the magnetic fields generated by the EMS 400-4.
- the electromagnetic stirring apparatus 500 includes a ferromagnetic core having six core elements 501a-f arranged in a ring-like configuration having a hexagonal shape. Each of the six core elements 501a-f have a longitudinal shape extending in the circumferential direction, and arc configured to join and abut each other at respective ends. Six windings 502a-f are wound on the ferromagnetic core such that the winding axis of each one of the six w indings 5n2a-f extends in the circumferential direction.
- An electromagnetic stirring apparatus is adapted to be mounted below a metal furnace, particularly below a hearth of a metal furnace.
- a metal furnace 100 having a hearth 101 is supported by a furnace frame 111 , Hearth mounting members 1 10 max be prov ided to mount the hearth 101 to the furnace frame 1 1 1
- fee electromagnetic stirring apparatus 500 particularly the stirring assembly of the electromagnetic stirring apparatus 500, is adapted to be mounted below a metal furnace with a mounting member 503.
- Mounting member 503 may further include a fastening means adapted for fastening the mounting member 503 to the furnace frame 111, for example, a bolted connection or a clamp connection.
- the electromagnetic stirring apparatus is mounted to a frame of the metal furnace.
- the present disclosure is not limited thereto, and the dectrornagnetic stirring apparatus may be mounted on a frame separate to the metal furnace.
- the electromagnetic stirring apparatus may be mounted on a frame which is fastened to a floor below the metal furnace.
- the electromagnetic stirring apparatus may be mounted to a mov able frame w hich is configured to be positioned below a metal furnace, allow ing for the electromagnetic stirring apparatus to be mox ed from one metal furnace to another.
- the electromagnetic stirring apparatus include a multiphase AC power supply electrically connected to the at least three windings.
- the multiphase AC power supply is configured to providing electrical currents in each of the at least three w indings to generate an electromagnetic stirring field for stirring a melt in the metal furnace.
- the multiphase AC power supply may include any power supply capable of pro ⁇ iding alternating current to each one of the at least three windings, such that the electrical current in one of the at least three windings may be adapted to be out of phase w ith the electrical current in another of the at least three windings.
- out-of-phase electrical Currents to a pair of the at least three windings, the windings generate a positive magnetic polarity and a negative magnetic polarity, generating a magnetic field which may be used to stir the melt.
- the multiphase AC power supply may be configured to provide a first electrical current in one of the at least three windings and a second electrical current in another one of the at least three windings, wherein the phase of the first electrical current is offset from the phase of the second electrical current.
- the phases of the respective electrical currents for each of the at least three windings are selected for generating an electromagnetic stirring field for producing a rotational stirring motion of the melt in the metal furnace when the electromagnetic stirring apparatus is mounted below the metal furnace.
- the term “electromagnetic stirring field” refers to one or more magnetic fields being generated by the electromagnetic stirring apparatus which cause the melt in the metal furnace to be moved in a stirring motion.
- the electromagnetic stirring field is adapted for rotational stirring about an axis of rotation, preferably a single vortex or axis of rotation, e.g., a predominantly vertical axis at a center region of the furnace.
- the at least three windings comprise pairs of windings, wherein the electrical currents have a predetermined constant phase difference between each pair of windings.
- each winding has a co rresponding other winding which forms a pair.
- the plurality of windings may respectively include a plurality of pairs of windings.
- the predetermined constant phase difference may be constant throughout the plurality of pairs of windings, i.e. the predetermined constant phase difference is the same for all pairs of windings.
- the phase of the electrical current in an n t h winding is selected to be offset from the phase of the electrical current in an (n+m) th winding, where n is an integer corresponding to the number of the winding in the circumferential direction, and m is an integer which is less than half of the total number of windings.
- the mul tiphase AC power suppl y may be a component mounted to the stirring assembly, or may be a component which is separate to the stirring assembly.
- the multiphase AC power supply may be configured for providing a number of phases corresponding to a factor of the number of windings.
- an electromagnetic stirring apparatus having six windings may include a multiphase AC power supply being configured for providing three-phase AC current.
- the multiphase AC power supply may be configured for providing electrical current having a frequency of 0.1 Hz or more, and/or 10 Hz or less.
- the multiphase AC power supply may be configured for providing electrical current having a variable frequency in the range of 0.1 Hz to 10 Hz.
- multiphase AC power supply is adapted for providing a total power of at least 10 kW and/or at most 1000 kW.
- the multiphase AC power supply may be adapted for providing electrical current having a variable power in the range of 10 kW to 1000 kW.
- the electromagnetic stirring apparatus max further include a controller configured for adjusting the phase of the electrical current in each of the at least three windings.
- the controller may be further adapted for adjusting the frequency and/or the magnitude of the electrical current in each of the at least three windings.
- the controller may include any suitable controller known in the state of the art which is capable of adjusting the parameters of the mul tiphase AC power supply
- the electromagnetic stirring apparatus may include one of a programmable logic controller (PLC), a digital signal processor (DSP), a distributed control system (DCS) or an analogue control system.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
Abstract
The present disclosure provides an. electromagnetic stirring apparatus for a metal furnace, including a stirring assembly having a ferromagnetic core arranged in a ring-like configuration, and at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration. The electromagnetic stirring apparatus further includes a multiphase AC power supply electrically connected to the at least three windings and a mounting member for mounting the stirring assembly below the metal furnace, wherein the multiphase AC power supply is configured for providing electrical currents to each of the at least three windings, the electrical currents being adapted for generating an electromagnetic stirring field for stirring a melt in the metal furnace when the stirring assembly is mounted below the metal furnace. The present disclosure further provides a metal furnace having the electromagnetic stirring apparatus, and a method for stirring a melt in a metal furnace.
Description
ELEC TROMAGNETIC STIRRING APPARATUS FOR A METAL FURNACE AND
METHOD OF OPERATION THEREOF
TECHNICAL FIELD
Embodiments of the present disclosure relate to an electromagnetic stirring apparatus for a metal furnace, particularly for an electric arc furnace, and a method of operation thereof
BACKGROUND
In a metal furnace of the present state of the art, a melt may be stirred using an electromagnetic stirrer (EMS), fa general, a metal furnace is a vessel for metal processing. A metal furnace in the context of the present disclosure may include, but is not limited to, an electric arc furnace ( EA F ) for steelmaking, an electric arc furnace for ferro-alloy (for example, FeMn or FeNi) refining, a ladle furnace for steel refining, an aluminium melting furnace for scrap recycling, an aluminium holding furnace for alloying and casting, a copper anode furnace for copper refining, or a lead melting furnace.
Electromagnetic stirring is beneficial for many reasons. For example, electromagnetic stirring allows for improved melting speed and reduced process time, improx ed temperature homogenization, and reduced energy consumption of the metal furnace. In a typical installation, such as in an EAF, the EMS is mounted below the hearth of the EAF) and the melt is stirred by the application of a magnetic field.
In the present state of the art, a typical EMS has a linear design, comprising a linear core element with two or more windings wound thereon Electric currents arc applied to the w indings so as to generate a magnetic field in the linear direction along the length of the core element. As such, the resulting stirring of the melt is performed only in a linear direction. The melt, when stirred linearly, encounters significant flow resistance when the flow reaches the walls of the hearth. Therefore, the electric energy consumption for stirring a melt using a linear EMS is high.
Further, the space available below the hearth of a metal furnace such as an EAF is typically limited, as the hearth is typically mounted on a large frame which allows for tilting of the EAF during tapping. The overall length of a linear EMS is limited by the space available in the frame.
In view of the deficiencies of electromagnetic stirrers in the current state of the art, an improved EMS having reduced energy consumption, improved stirring and a more space efficient design is desired.
SUMMARY
In view of the above challenges and problems arising in the state of the art, improved methods and systems for electromagnetic stirring in a metal furnace are sought.
According to a first aspect of the present disclosure, an electromagnetic stirring apparatus for a metal furnace is provided. The electomagiietic stirring apparatus includes a stirring assembly having a ferromagnetic core arranged in a ring-like configuration, and at least three windings which are wound on the ferromagnetic core such that a w inding avis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration. The electromagnetic stirring apparatus further includes a multiphase AC power supply electrically connected to the at least three windings and a mounting member for mounting the stirring assembly below the metal furnace, wherein the multiphase AC power supply is configured for providing electrical currents to each of the at least three windings, the electrical currents being adapted for generating an electromagnetic stirring field for stirring a melt in the metal furnace when the stirring assembly is mounted below the metal furnace.
According to a second aspect of the present disclosure, a metal furnace is provided. The metal furnace includes an electromagnetic stirring apparatus according to the first aspect arranged below the furnace.
According to a third aspect of the present disclosure, a method for stirring a melt in a metal furnace is provided. The method includes providing a stirring assembly below the metal furnace, the stirring assembly having a ferromagnetic core arranged in a ring-like configurationand at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration. The method further includes providing electrical currents in each of the at least three windings, wherein the electrical currents are adapted for generating an electromagnetic stirring field for stirring the melt in the metal furnace when the stirring assembly is prov ided below the metal furnace.
Aspects of the present disclosure provide apparatus and methods for more energy efficient stirring of a melt in a metal furnace as compared to solutions known in the state of the art. Further, the improved apparatus of the present disclosure allows for increased flexibility and improved stirring of the melt, and allows for a more space efficient design suitable forapplications where space below the hearth of an EAF is restricted.
Those skilled in the art will recognise additional features and adv antages upon reading the following detailed description, and upon viewing the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The components in the figures are not necessarily to scale, instead emphasis being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts. In the drawings:
Fig. 1 illustrates a schematic side view of an electric arc furnace having an electromagnetic stirring apparatus according to embodiments of the present invention;
Fig. 2a illustrates a schematic top view of an electric arc tanace having an electromagnetic stirring apparatus according to the current state of the art;
Fig. 2b illustrates a schematic top view of a melt flow in an electric arc tanace having an electromagnetic stirring apparatus according to the current state of the art;
Fig. 3 a illustrates a schematic top view of an electric arc tanace having an electromagnetic stirring apparatus according to embodiments of the present invention;
Fig. 3b illustrates a schematic top view of a melt flow in an electric arc furnace having an electromagnetic stirring apparatus according to embodiments of the present invention;
Fig. 4a-4d illustrate schematic top views of an electromagnetic stirring apparatus according to embodiments of the present invention;
Fig. 5 illustrates a schematic top view of an electromagnetic stirring apparatus according to embodiments of the present invention; and
Fig. 6 illustrates a schematic front view of an electric arc furnace having an electromagnetic stirring apparatus according to embodiments of the present invention.
DETAILED DESCRIPTION
Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by w ay of explanation and is not meant as a limitation For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment.
It is intended that the present disclosure includes such modifications and variations.
Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment applies to a corresponding part or aspect in another embodiment as well.
Reference will first be made to Fig. 1, which shows an exemplary side section view of a metal furnace. The metal furnace as exemplarily shown in the figures is an electric arc furnace ( EAF ) 100, however the present disclosure is not limited thereto. For example, the metal furnace may include any one of an electric arc furnace ( EAF) for steelmaking, an electric arc furnace for ferro-alloy (for example, FeMn or FeNi) refining, a ladle furnace for steel refining, an aluminium melting furnace for scrap recycling, an aluminium holding furnace for alloying and casting, a copper anode furnace for copper refining, a lead melting furnace, or any other suitable metal furnace known in the art.
In the context of the present disclosure, the term “a melt” refers to a volume of material being processed in a metal furnace. Particularly, the melt is a volume of material in a metal furnace which is to be stirred by an electromagnetic stirrer. The melt may refer to a volume of material which is completely molten, or may refer to a v olume of material w hich is partially molten and partially solid. The material may include a metal or a metal alloy Particularly the volume of material is an electrically conductive metal, or may include electrically conductive metal in at least a portion of the volume of material.
The electric arc furnace 100 includes a hearth 101 having a bowl shape, particularly having an egg-shaped cross section when v iewed from above. The hearth 101 is lined w ith a refractory lining 102 and a working lining 103 In the ease of a DC EAF , the working lining 103 may be a conductiv e lining, c.g a graphite lining. The hearth 101 contains the melt M. which is the material to be melted in the metal furnace Graphite electrodes 105 arc mov able mounted to the roof (not shown) of the electric arc furnace 100, and arc configured for generating one or more electric arcs to provide heat to the melt M. The EAF 100 exemplarily shown in the figures is an AC EAF which includes three electrodes 105. The electrodes 105 are configured to be movable in the vertical direction in order to control the arc generation as the electrodes 105 wear
The electric arc furnace 100 max be configured for tapping or pouring the melt M In this arrangement, the electric arc furnace 100 is mounted on a frame configured for tilting the electric arc furnace 100 m a tapping or pouring process, \n eccentric bottom tap-hole (EBT) 104 is prov ided at one end of the hearth 101 for the melt M to flow from the hearth 101Arranged below the hearth 101 of the electric arc furnace 100 is an electromagnetic stirrer (EMS) 200, 300, 400, 500. The EMS is configured to generate magnetic fields which penetrate the shell of the hearth 101 and the respectiv e linings 102, 103 and act on the melt M By applying magnetic fields, the meh M can be stirred so as to liquefy the material in the melt M faster more effectiv ely and with better temperature homogeneity The EMS typically includes an AC power supply, which may be mounted io the EMS or may be external to the LMS. to apply electrical currents and generate the magnetic fields.
In the current state of the art, the electromagnetic stirrer provided beneath the hearth 101 is a linear EMS 200. A linear EMS 200 according to the current state of the art is exemplarily show in Fig, 2a. w hich show s a top v iew of a hearth 101 of a metal furnace. The metal furnace includes a linear EMS 200 arranged below the hearth 101. A typical linear EMS 200 includes
a ferromagnetic core 201 and a plurality of windings 202a-f wound around the ferromagnetic core 201. A multiphase AC power supply provides electrical currents to each one of the plurality of windings 202a-f such that a magnetic field is generated and applied to the melt M inside the hearth 101 of the metal furnace. Fig. 2a further shows an exemplary shape of the hearth 101 and the location of the eccentric bottom tap-hole 104.
The resulting flow pattern of the melt being stirred by the exemplary linear EMS 200 is illustrated in Fig. 2b. Since the magnetic field generated by the linear EMS 200 is only Ale to be applied to the melt M in a linear direction, the melt M can only be directed in a direction along the length of the linear EMS 200 and directly towards the wall of the hearth 101. When the melt flow impinges on the wall of the hearth 101, the flow changes direction to flow aroundand parallel to the wall of the hearth 101 . The melt flow encounters significant resistance when reaching the wall of the hearth 101. and the electric energy consumed by the linear EMS 200 to overcome the melt flow resistance is high.
In addition to the high electric energy consumption, the dimensions of the linear EMS 200 may also be disadvantageous for implementing electromagnetic stirring on the metal furnace.
Particularly, a linear EMS 200 of the present state of fee art has a larger size to generate sufficient force to overcome the melt flow resistance, and challenges may arise when allocating space below the metal furnace due to the excessive length of the linear EMS 200 For example, it may be challenging to provide sufficient space for a linear EMS 200 in a support frame design for the metal furnace, particularly a metal furnace mounted on a support frame designed to be lilted during a tapping or pouring process.
The present disclosure provides an EMS and methods for stirring a melt to solve the problems associated with the use of a linear EMS in metal furnaces. An EMS according to embodiments of the present disclosure offers reduced electric energy consumption, improved flexibility and
more compact dimensions by implementing a ring-like configuration. An EMS according to the present disclosure is exemplarily shown in Fig. 3a.
According to an aspect of the present disclosure, an electromagnetic stirring apparatus for a metal furnace including a stirring assembly having a ferromagnetic core arranged in a ring-like configuration and at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration. The electromagnetic stirring apparatus farther includes a multiphase AC powersupply electrically connected to the at least three windings and a mounting member for mounting the stirring assembly below the metal furnace (e.g. with the mounting member mechanically connected to the core and extending therefrom e.g.. upw ardly
- to atach the stirring apparatus to the metal furnace above), wherein the multiphase AC power supply is configured for pro\ iding electrical currents in each of the at least three w indings, the electrical currents being adapted for generating an electromagnetic stirring field for stirring a melt in the metal furnace when the stirring assembly is mounted below the metal furnace. According to a farther aspect, the stirring apparatus is used below the metal furnace, i.e, below the melt contained in the metal furnace.
According to a further aspect of the present disclosure, a metal furnace having a hearth and the electromagnetic stirring apparatus as described herein is provided, wherein the electromagnetic stirring apparatus is arranged bclov the furnace. Particularly, the electromagnetic stirring apparatus is arranged below the heart of the metal furnace. The metal furnace may be any one of an electric arc furnace for ferro-alloy (for example, FcMn or FcNi ) refining, a ladle furnace for steel refining, an aluminium melting furnace for scrap recycling, an aluminium holding furnace for alloy inti and casting, a copper anode furnace for copper refining, a lead melting furnace. In a preferred embodiment, the metal furnace is an electric arc furnace.
According to a yet further aspect of the present disclosure, a method for stirring a melt in a metal furnace is provided. Particularly the method relates to stirring a melt in a metal fomace using the electromagnetic stirring apparatus described herein. The method includes providing a stirring assembly below the metal furnace, the stirring assemble having a ferromagnetic corearranged in a ring-like configuration and at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration. The method further includes providing electrical currents in each of the at least three windings, wherein the electrical currents are adapted for generating an electromagnetic stirring field for stirring the melt in the metal furnace when the stirring assembly is provided below the metal furnace. According to embodiments of the present disclosure, the method for stirring a melt in a metal furnace is provided, wherein the metal furnace is an electric are fomace.
The electromagnetic stirring apparatus 300 includes a stirring assembly, which is arranged below the hearth 101 of the metal furnace. The stirring assembly includes the elements which are configured for generating magnetic fields w hich are used to stir the melt M. Particularly, the stirring assembly includes a ferromagnetic core 301 arranged in a ring-like configuration, and at least three windings 302a-f wound on the ferromagnetic core. When a current is applied to the at least three windings 302a-f such that a phase difference exists between the currents in two or more windings, a magnetic field is generated for stirring the melt M. In the EMS 300 exemplarily shown in Fig. 3a. six w indings 302a-f are provided. and the ferromagnetic core has a hexagonal ring-like configuration.
The ferromagnetic core 301 of the stirring apparatus may include at least one core element arranged in a ring-like configuration. In the most basic sense, the ferromagnetic core may include a single element having a ring-like shape. For example, the ferromagnrtic rare may include a single piece of ferromagnetic metal formed into a closed ring, for example, a toroid
shape. However, a single core element may be impractical for a number of reasons, including challenging manufacturing and assembly of the windings 302a-f thereon. Thus, in preferred embodiments, the ferromagnetic core 301 may include a plurality of core elements arranged in a ring-like configuration. For example, a ferromagnetic core 301 may be formed by arranging a plurality of core elements each having a longitudinal shape into a ring-like configuration in the shape of a polygon. Alternatively foe plurality of core elements may each have an arc shape which, when arranged in a ring-like configuration, form the shape of a circle.
The plurality of core elements of the ferromagnetic core 301 may be arranged so that they join and abut each other at their respective ends, so that the ferromagnetic core 301 is a closed loop. Alternatively, the plurality of core elements may be arranged with a gap therebetween. In both cases, the ferromagnetic core 301 essentially forms an arrangement where the ferromagnetic core 301 is a magnetic loop, wherein the magnetic field within the ferromagnetic core 301 is a closed loop around the ring-like configuration.
In the context of the present disclosure, the term “ring-like configuration” refers to the overall shape of a ring. The ring-like configuration may be uniform or non-uniform. Particularly the ring-likc configuration refers to an arrangement of at least one object lying on a contour having a start point, where said contour circumscribes a circuit, and returns to an end point which is the same as the start point. For example, the ring-like configuration may be an arrangement of objects lying on a ring-like contour, such as a circle, an oval or a polygon. The arrangement of objects on the contour may be continuous, for example, where the objects join or abut to one mother to form a closed circuit, or the arrangement of objects on the contour may be discontinuous, for example, where the objects have spaces therebetween.
Further, the ring-like configuration defines a circumferential direction, which is the direction along the contour of the ring-like configuration. For example, for a ring-like configuration having a contour in a circular shape, the circumferential direction is the direction around the
circle. As a further example, for a ring-like configuration having a contour in a polygonal shape, the circumferential direction is the direction around the polygon.
The w indings 302 a-f of the stirring apparatus arc arranged on the ferromagnetic core 301 such that a magnetic field is generated when electric currents are provided to two respective windings 302a-f Each respective winding 302a-f is wound on the ferromagnetic core 301 such that a winding axis of each respective winding 302a-f extends in a circumferential direction with respect to the ring-like configuration. The respective windings 302a-f are wound around the ferromagnetic core 301. Preferably, the windings 302a-f are evenly spaced around the ring-like configuration in the circumferential direction.
When referring to an axis extending in the circumferential direction with respect to the ringlike configuration, the axis is defined as a line extending tangential to the circumferential direction at a point around the contour of the ring-like configuration. For example, for a ringlike configuration having a contour in a circular shape, the axis extending in the circumferential direction is a line extending tangential to the circle. As a further example, for a ring-like configuration having a contour in a polygonal shape, the axis extending in the circumferential direction is a line extending coincident with a line segment of the polygon.
As exemplarily shown in Fig. 3a, the number of windings 302a-f is six. However, the present disclosure is not limited thereto. In general, the minimum number of windings 302a-f to achieve appropriate stirring is three. There is a balance to be made between the number of windings 3()2a-f and the size of the windings 302 a-f, as more windings may allow for a more ring-like magnetic field and resulting stirring action, but may restrict the size of the windings and the strength of the magnetic field which may be applied. The number of windings may also depend on the shape of the ring-like con figuration, and/or the number of core elements included in the ferromagnetic core 301. Preferably, the number of windings 302a-f is at least six
windings. More preferably the number of windings 302a-f is at least one winding per core element included in the ferromagnetic core 301.
The resulting flow pattern of the melt being stirred by the EMS 300 according to the present disclosure is illustrated in Fig. 3b. The magnetic fields generated by the EMS 300 allow for a rotational flow of the melt M, such that the melt M is stirred around the hearth 101 instead of end-to-end as with a linear EMS. As a result, the melt M is not directed such that the melt flow impinges directly on the wall of the hearth 101. This rotational flow of the melt M exhibits si gni flcantl y lower flow resistance as compared to the end-to-end flow caused by a linear EMS.
As a result, the strength of the magnetic field for stirring the melt M may be reduced, and consequently, the electric energy consumption of the EMS 300 is significantly reduced The
EMS 300 according to embodiments of the present disclosure thus allows for improved stirring efficiency. Further still, due to the reduced strength of the magnetic field for stirring the melt M, the EMS 300 may be reduced in size as compared to a linear EMS, allowing for the EMS 300 to be more compact. Particularly, the EMS 300 may be easily adaptable to metal furnaces configured for tilting in a tapping or pouring process, which typically would have a sizeable mounting frame below the hearth 101 .
Reference will now be made to Figs. 4A-4D, which exemplarily show electromagnetic stirrers 400-1, 400-22, 400-3, 400-4 according to embodiments of the present disclosure. The exemplary electromagnetic stirrers 400-1, 400-2, 400-3, 400-4 include different arrangements of ferromagnetic cores 301 and windings 302 arranged in different ring-like configurations.
According to embodiments, which may be combined with other embodiments described herein, the electromagnetic stirring apparatus includes at least three core elements, wherein the at least three core elements have a longitudinal shape extending tangentially to the circumferential direction, and the ring-like configuration is preferably a polygonal configuration having at least three sides.
Fig. 4 A exemplarily shows an EMS 400-1 having a ring-like configuration in the shape of a triangle. The ferromagnetic core includes three core elements 401a-c extending along the cireumferential direction of the ring-like configuration, and six windings 402a-f are wound thereon. Each of the three core elements 401 a-c are shown as having a gap therebetween, however the arrangement of the three core elements in a ring-like configuration forms a magnetic circuit through the ferromagnetic core. The exemplary EMS 400-1 has advantages in low complexity and a compact design suitable for smaller metal furnaces, or metal furnaces with restricted space beneath foe hearth. The triangular ring-type configuration may also be more suitable for stirring a melt in an egg-shaped hearth due to their similar shapes. Fig 4B exemplary show s an EMS 400-2 ha\ ing a ring-type configuration in the shape ofa four- sided polygon, particularly a square. The four-sided polygon, however; may instead be a rectangle or an irregular quadrilateral. The ferromagnetic core includes four core elements 401a-d arranged to form a magnetic circuit through the ferromagnetic core Such an EMS 400-2 may be suitable for maximising the use of av ailable space beneath metal furnaces having a mounting frame, as such a frame typically provides a rectangular-shaped area for the EMS.
Similar to the example EMS 400-1 shown in Fig. 4A, the EMS 400-2 includes two windings 302a-h per core element 301 a-d for a total of eight windings 302a-h. With a higher number of windings 302a-h, this configuration may allow for more flexibility in control, e.g, by allowing for more variety in winding pairings to be configured. Fig. 4C exemplarily shows an EMS 400-3 having a ring-type configuration in the shape of a six-sided polygon, particularly a hexagon. The ferromagnetic core includes six core elements 401a-fr and six windings 402a-f are wound thereon. A configuration having one winding per core element allows for largerw indings to bc installed, w hich may allow for a stronger magnetic field for stirring the melt.
The two examples shown in Fig. 4B and 4C further allow for a space to be provided at the centre of the ring-like configuration . These designs may be advantageous for use in a DC EAF having a large electrode protruding from the botom of the hearth.
According to embodiments, which may be combined with other embodiments described herein, the electromagnetic stirring apparatus includes at least tw o core elements, wherein the at least two core elements have an arc shape extending in the cireumferential direction, and the ringlike configuration is preferably a circular configuration or an oval configuration.
Fig. 4D exemplarily shows an EMS 400-4 having a ring-type configuration in the shape of a circle. This example di tiers from the examples of Figs. 4A-4C in that the ferromagnetic core includes a plurality of arc-shaped core elements 401a-f Arc-shaped core elements 401a-f may generate a more uniformly circular magnetic field, allowing for uniform circular stirring of the melt, which may be more efficient than an EMS having longitudinal-shaped core elements. Further, the ends of each respective core element 401a-f are joined and abuted to each other, forming a closed loop ferromagnetic core. Abuting the core elements may improve the strength of the magnetic fields generated by the EMS 400-4.
Reference w ill now be made to Fig 5. w hich show s a top schematic view of an electromagnetic stirring apparatus 500 in a preferred configuration. The electromagnetic stirring apparatus 500 includes a ferromagnetic core having six core elements 501a-f arranged in a ring-like configuration having a hexagonal shape. Each of the six core elements 501a-f have a longitudinal shape extending in the circumferential direction, and arc configured to join and abut each other at respective ends. Six windings 502a-f are wound on the ferromagnetic core such that the winding axis of each one of the six w indings 5n2a-f extends in the circumferential direction.
An electromagnetic stirring apparatus according to aspects and embodiments of the present disclosure is adapted to be mounted below a metal furnace, particularly below a hearth of a
metal furnace. Referring now to Fig, 6, which shows a side view of a metal furnace having an electromagnetic stirring apparatus according to embodiments of the present disclosure, a metal furnace 100 having a hearth 101 is supported by a furnace frame 111 , Hearth mounting members 1 10 max be prov ided to mount the hearth 101 to the furnace frame 1 1 1 In the embodiment shown in Figs. 5 and 6, fee electromagnetic stirring apparatus 500, particularly the stirring assembly of the electromagnetic stirring apparatus 500, is adapted to be mounted below a metal furnace with a mounting member 503. Mounting member 503 may further include a fastening means adapted for fastening the mounting member 503 to the furnace frame 111, for example, a bolted connection or a clamp connection. In exemplary embodiments, the electromagnetic stirring apparatus is mounted to a frame of the metal furnace. However, the present disclosure is not limited thereto, and the dectrornagnetic stirring apparatus may be mounted on a frame separate to the metal furnace. For example, the electromagnetic stirring apparatus may be mounted on a frame which is fastened to a floor below the metal furnace. Alternatively, the electromagnetic stirring apparatus may be mounted to a mov able frame w hich is configured to be positioned below a metal furnace, allow ing for the electromagnetic stirring apparatus to be mox ed from one metal furnace to another.
The electromagnetic stirring apparatus according to embodiments of the present disclosure include a multiphase AC power supply electrically connected to the at least three windings. The multiphase AC power supply is configured to providing electrical currents in each of the at least three w indings to generate an electromagnetic stirring field for stirring a melt in the metal furnace. The multiphase AC power supply may include any power supply capable of pro\ iding alternating current to each one of the at least three windings, such that the electrical current in one of the at least three windings may be adapted to be out of phase w ith the electrical current in another of the at least three windings. By applying out-of-phase electrical Currents to a pair
of the at least three windings, the windings generate a positive magnetic polarity and a negative magnetic polarity, generating a magnetic field which may be used to stir the melt.
According to embodiments, which may be combined with other embodiments described herein, the multiphase AC power supply may be configured to provide a first electrical current in one of the at least three windings and a second electrical current in another one of the at least three windings, wherein the phase of the first electrical current is offset from the phase of the second electrical current.
According to embodiments, which may be combined with other embodiments described herein, the phases of the respective electrical currents for each of the at least three windings are selected for generating an electromagnetic stirring field for producing a rotational stirring motion of the melt in the metal furnace when the electromagnetic stirring apparatus is mounted below the metal furnace. In the context of the present disclosure, the term “electromagnetic stirring field” refers to one or more magnetic fields being generated by the electromagnetic stirring apparatus which cause the melt in the metal furnace to be moved in a stirring motion. According to an aspect, the electromagnetic stirring field is adapted for rotational stirring about an axis of rotation, preferably a single vortex or axis of rotation, e.g., a predominantly vertical axis at a center region of the furnace.
According to embodiments, which may be combined with other embodiments described herein, the at least three windings comprise pairs of windings, wherein the electrical currents have a predetermined constant phase difference between each pair of windings. Particularly, each winding has a co rresponding other winding which forms a pair. The plurality of windings may respectively include a plurality of pairs of windings. The predetermined constant phase difference may be constant throughout the plurality of pairs of windings, i.e. the predetermined constant phase difference is the same for all pairs of windings.
According to embodiments, which may be combined with other embodiments described herein, the phase of the electrical current in an nt h winding is selected to be offset from the phase of the electrical current in an (n+m)th winding, where n is an integer corresponding to the number of the winding in the circumferential direction, and m is an integer which is less than half of the total number of windings. For example, in an electromagnetic stirring apparatus having six windings, the 1st winding may be adjusted to be out of phase with either the 2nd winding (m=l) or the 3rd winding (m=2). As a further example, in an electromagnetic stirring apparatus having eight windings, the 1st winding may be adjusted to be out of phase with either the 2nd winding (m=1), the 3rd winding (m=2) or the 4* winding (m=3). Further; the configuration of pairs or windings may be adjusted depending on a stirring mode.
In embodiments of the present disclosure, the mul tiphase AC power suppl y may be a component mounted to the stirring assembly, or may be a component which is separate to the stirring assembly. The multiphase AC power supply may be configured for providing a number of phases corresponding to a factor of the number of windings. For example, an electromagnetic stirring apparatus having six windings may include a multiphase AC power supply being configured for providing three-phase AC current. The multiphase AC power supply may be configured for providing electrical current having a frequency of 0.1 Hz or more, and/or 10 Hz or less. Particularly, the multiphase AC power supply may be configured for providing electrical current having a variable frequency in the range of 0.1 Hz to 10 Hz. According to embodiments, which may be combined with other embodiments described herein, foe multiphase AC power supply is adapted for providing a total power of at least 10 kW and/or at most 1000 kW. Particularly the multiphase AC power supply may be adapted for providing electrical current having a variable power in the range of 10 kW to 1000 kW.
According to embodiments, which may be combined with other embodiments described herein, the electromagnetic stirring apparatus max further include a controller configured for adjusting
the phase of the electrical current in each of the at least three windings. The controller may be further adapted for adjusting the frequency and/or the magnitude of the electrical current in each of the at least three windings. The controller may include any suitable controller known in the state of the art which is capable of adjusting the parameters of the mul tiphase AC power supply For example, the electromagnetic stirring apparatus may include one of a programmable logic controller (PLC), a digital signal processor (DSP), a distributed control system (DCS) or an analogue control system.
Although various exemplary embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the ad\ antages of the invention w ithout departing from the spirit and scope of the invention. It will be obvious to those reasonably skilled in the art that other components performing the same functions may be suitably substituted. It should be mentioned that features explained with reference to a specific figure may be combined with features of other figures, even in those cases in which this has not explicitly been mentioned. Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper” and the like are used for case of description io explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. andare also not intended to be limiting, Like terms refer to like elements throughout the description.
As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional dements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise .
With the above range of variations and applications in mind, it should be understood that the present invention is not limited by the foregoing description, nor is it limited by the accompanying drawings. Instead, the present invention is limited only by the following claims and their legal equi valents. Reference numbers
100 Metal furnace
101 Hearth
102 Refractory lining
103 Working lining 104 Eccentric bottom tap-hole (EBT)
105 Electrodes
110 Hearth mounting member
111 Furnace frame
200, 300, 400, 500 Electromagnetic stirring apparatus 201, 301 Ferromagnetic core
202a-f 302a-f, 402a-h Winding
401a-f, 501a-f Core element
503 Mounting member
M Melt
Claims
1. An electromagnetic stirring apparatus for a metal furnace, comprising: a stirring assembly comprising: a ferromagnetic core arranged in a ring-like configuration; and at least three windings which are wound on the ferromagnetic core such that a winding axis of each one of the at least three windings extends in a circumferential direction with respect to the ring-like configuration; a multiphase AC power supply electrically connected to the at least three windings; and a mounting member for mounting the stirring assembly below the metal furnace, wherein the multiphase AC power supply is configured for providing electrical currents in each of the at least three windings, the electrical currents being adapted for generating an electromagnetic stirring field for stirring a melt in the metal fomace when the stirring assembly is mounted below the metal furnace.
2. The electromagnetic stirring apparatus according to claim 1, wherein the ferromagnetic core comprises at least three core elements, wherein the at least three core elements have a longitudinal shape extending tangential to the circumferential direction, and the ring-like configuration is preferably a polygonal configuration having at least three sides.
3. The electromagnetic stirring apparatus according to claim 1, wherein the ferromagnetic core comprises at least two core elements, wherein the at least two core elements have an arc shape extending in the circumferential direction, and the ring-like configuration is preferably a circular configuration or an oval configuration.
4. The electromagnetic stirring apparatus according to any one of the preceding claims, wherein the multiphase AC power supply is configured to provide a first electrical current in one of the at least three windings and a second electrical current in another one of the at least three windings, wherein the phase of the first electrical current is offset from the phase of the second electrical current.
5. The electromagnetic stirring apparatus according to any one of the preceding claims, wherein the phases of the respective electrical currents for each of the at least three windings are selected for generating an electromagnetic stirring field for producing a rotational stirring motion of the melt in the metal furnace when the electromagnetic stirring apparatus is mounted below the metal furnace.
6. The electromagnetic stirring apparatus according to any one of the preceding claims, wherein the at least three windings comprise pairs of windings, and wherein the electrical currents have a predetermined constant phase difference between each pair of windings.
7. The electromagnetic stirring apparatus according to any one of the preceding claims, wherein: the phase of the electrical current in an nth w inding is selected to be offset from the phase of the electrical current in an (n+m)* winding, w here n is an integer corresponding to the number of the w inding in the circumferential direction, and m is an integer which is less than half of the total number of windings.
8. The electromagnetic stirring apparatus according to any one of claims 1 to 7, wherein the multiphase AC power supply comprises a controller configured for adjusting the phase of the electrical current in each of the at least three windings.
9. The electromagnetic stirring apparatus according to any one of the preceding claims, wherein the multiphase AC power supply is adapted for providing a total power of at least 10 kW and/or at most 1000 kW.
10. A metal furnace having a hearth and the electromagnetic stirring apparatus according to any one of claims 1 to 9 arranged below the metal furnace.
11. The metal fomace according to claim 10, wherein the metal furnace is an electric arc famace.
12. Method for stirring a melt in a metal famace, comprising: prox iding a stirring assembly below the metal furnace, the stirring assembly comprising: a ferromagnetic core arranged in a ring-like configuration; and at least three windings which are wound on the ferromagnetic core such that a w inding axis of each one of the at least three w indings extends in a circumferential direction with respect to the ring-like configuration; and prox iding electrical currents in each of rhe at least three w indings. wherein the electrical currents are adapted for generating an electromagnetic stirring field for stirring the melt in the metal famace when the stirring assembly is provided below the metal furnace.
13. The method according to claim 12, wherein the electrical currents include a first electrical current in one of the at least three windings and a second electrical current in another one of the at least three windings, wherein the phase of the first electrical current is offset from the phase of the second electrical current .
14. The method according to claim 12, wherein the phases of the respective electrical currents for each of the at least three windings are selected for generating an electromagnetic stirring field for producing a rotational stirring motion of the melt in the metal furnace.
15. The method according to claim 12, wherein the at least three windings comprise pairs of windings, and wherein the electrical currents have a predetermined constant phase difference between each pair of windings.
16. The method according to claim 12, wherein: the phase of the first electrical current in an nth winding is controlled to be offset from the phase of the second electrical current in an (n+m)th winding, where n is an integer co rresponding to the number of the winding in the circumferential direction, and m is an integer which is less than half of the total number of windings.
17. The method according to any one of claims 12 to 16, wherein the metal furnace is an electric arc furnace.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/EP2021/072643 WO2023016663A1 (en) | 2021-08-13 | 2021-08-13 | Electromagnetic stirring apparatus for a metal furnace and method of operation thereof |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/EP2021/072643 WO2023016663A1 (en) | 2021-08-13 | 2021-08-13 | Electromagnetic stirring apparatus for a metal furnace and method of operation thereof |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2023016663A1 true WO2023016663A1 (en) | 2023-02-16 |
Family
ID=77666475
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2021/072643 WO2023016663A1 (en) | 2021-08-13 | 2021-08-13 | Electromagnetic stirring apparatus for a metal furnace and method of operation thereof |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2023016663A1 (en) |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3309498A1 (en) * | 1983-03-17 | 1984-09-20 | Leningradskoe proizvodstvennoe elektromašinostroitel'noe obedinenie "Elektrosila" imeni S.M. Kirova, Leningrad | Stator of an electromagnetic mixer |
JP2003207283A (en) * | 2002-01-15 | 2003-07-25 | Sumitomo Electric Ind Ltd | Method and device for mixing molten metal |
CN106914183A (en) * | 2017-04-05 | 2017-07-04 | 东北大学 | A kind of rotary EMS device for being arranged on metal bath furnace bottom |
CN110686510A (en) * | 2019-10-16 | 2020-01-14 | 山东大学 | Inductor structure and electromagnetic stirring smelting pot |
WO2020052794A1 (en) * | 2018-09-10 | 2020-03-19 | Ergolines Lab S.R.L. | Electromagnetic stirring device in a mould for casting aluminium or aluminium alloys, stirring method in a mould for casting aluminium or aluminium alloys, mould and casting machine for casting aluminium or aluminium alloys |
WO2021053701A1 (en) * | 2019-09-19 | 2021-03-25 | Danieli & C. Officine Meccaniche S.P.A. | Method of stirring liquid metal in an electric arc furnace |
WO2022028728A1 (en) * | 2020-08-04 | 2022-02-10 | Ergolines Lab S.R.L. | Agitation device and method for melting furnace and melting furnace |
-
2021
- 2021-08-13 WO PCT/EP2021/072643 patent/WO2023016663A1/en unknown
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3309498A1 (en) * | 1983-03-17 | 1984-09-20 | Leningradskoe proizvodstvennoe elektromašinostroitel'noe obedinenie "Elektrosila" imeni S.M. Kirova, Leningrad | Stator of an electromagnetic mixer |
JP2003207283A (en) * | 2002-01-15 | 2003-07-25 | Sumitomo Electric Ind Ltd | Method and device for mixing molten metal |
CN106914183A (en) * | 2017-04-05 | 2017-07-04 | 东北大学 | A kind of rotary EMS device for being arranged on metal bath furnace bottom |
WO2020052794A1 (en) * | 2018-09-10 | 2020-03-19 | Ergolines Lab S.R.L. | Electromagnetic stirring device in a mould for casting aluminium or aluminium alloys, stirring method in a mould for casting aluminium or aluminium alloys, mould and casting machine for casting aluminium or aluminium alloys |
WO2021053701A1 (en) * | 2019-09-19 | 2021-03-25 | Danieli & C. Officine Meccaniche S.P.A. | Method of stirring liquid metal in an electric arc furnace |
CN110686510A (en) * | 2019-10-16 | 2020-01-14 | 山东大学 | Inductor structure and electromagnetic stirring smelting pot |
WO2022028728A1 (en) * | 2020-08-04 | 2022-02-10 | Ergolines Lab S.R.L. | Agitation device and method for melting furnace and melting furnace |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP2641140B2 (en) | Method for melting scrap iron and electric furnace for carrying out the method | |
US3789127A (en) | Arc furnaces | |
US3949151A (en) | Arc furnaces | |
KR101420067B1 (en) | Apparatus and method for electromagnetic stirring in an electrical arc furnace | |
JP4831917B2 (en) | Method and apparatus for continuous casting of metal using mold | |
JP2004108666A (en) | Crucible-shaped induction furnace | |
WO2023016663A1 (en) | Electromagnetic stirring apparatus for a metal furnace and method of operation thereof | |
CN111842821B (en) | Electromagnetic treatment method for melt cast by aluminum alloy flow table | |
US4856021A (en) | Electric direct-current scrap-melting furnace | |
US11612931B2 (en) | Electromagnetic stirring device in a mould for casting aluminium or aluminium alloys, stirring method in a mould for casting aluminium or aluminium alloys, mould and casting machine for casting aluminium or aluminium alloys | |
JP3209845B2 (en) | DC arc furnace | |
JP2001512182A (en) | Apparatus and method for stirring molten metal using an electromagnetic field | |
US6026113A (en) | Method for the electromagnetic stirring of the liquid metal in electric arc furnaces and relative device | |
JP2940134B2 (en) | Dc arc furnace | |
RU2040864C1 (en) | Direct current smelting furnace | |
RU2486717C2 (en) | Electric arc dc furnace | |
CN1056568A (en) | Direct current electric arc furnace | |
WO2022117219A1 (en) | Control method of stirring device and stirring device | |
WO2022028728A1 (en) | Agitation device and method for melting furnace and melting furnace | |
RU2731947C1 (en) | Furnace device for metal production process | |
JP2613805B2 (en) | DC arc furnace | |
JP7315261B1 (en) | Magnetic field generator and molten metal driving system | |
US4034146A (en) | Method and apparatus for equalizing the wall lining wear in three phase alternating current electric arc furnaces | |
RU126810U1 (en) | DC ELECTRIC ARC FURNACE | |
RU2192713C1 (en) | Power supply unit |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 21766404 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |