WO2004036131A1 - Four electrique pour la production d'acier - Google Patents

Four electrique pour la production d'acier Download PDF

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Publication number
WO2004036131A1
WO2004036131A1 PCT/IB2002/004243 IB0204243W WO2004036131A1 WO 2004036131 A1 WO2004036131 A1 WO 2004036131A1 IB 0204243 W IB0204243 W IB 0204243W WO 2004036131 A1 WO2004036131 A1 WO 2004036131A1
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WO
WIPO (PCT)
Prior art keywords
furnace
shell
tap hole
heat
electric
Prior art date
Application number
PCT/IB2002/004243
Other languages
English (en)
Inventor
Michael J. Stercho
Original Assignee
Sms Demag Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sms Demag Ag filed Critical Sms Demag Ag
Priority to PCT/IB2002/004243 priority Critical patent/WO2004036131A1/fr
Publication of WO2004036131A1 publication Critical patent/WO2004036131A1/fr

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Classifications

    • 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
    • C21C5/5294—General arrangement or layout of the electric melt shop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
    • F27B3/06—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces with movable working chambers or hearths, e.g. tiltable, oscillating or describing a composed movement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
    • F27B3/08—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces heated electrically, with or without any other source of heat
    • F27B3/085—Arc furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
    • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
    • F27B3/18—Arrangements of devices for charging
    • F27B3/183—Charging of arc furnaces vertically through the roof, e.g. in three points
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
    • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
    • F27B3/19—Arrangements of devices for discharging
    • 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
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/18—Door frames; Doors, lids, removable covers
    • F27D1/1808—Removable covers
    • F27D1/1816—Removable covers specially adapted for arc furnaces
    • 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
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/001—Extraction of waste gases, collection of fumes and hoods used therefor
    • 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
    • F27D3/0025—Charging or loading melting furnaces with material in the solid state
    • 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
    • F27D3/12—Travelling or movable supports or containers for the charge
    • F27D3/123—Furnace cars
    • 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
    • F27D3/14—Charging or discharging liquid or molten material
    • 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
    • F27D3/15—Tapping equipment; Equipment for removing or retaining slag
    • F27D3/1509—Tapping equipment
    • F27D3/1527—Taphole forming equipment, e.g. boring machines, piercing tools
    • 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
    • F27D3/15—Tapping equipment; Equipment for removing or retaining slag
    • F27D3/1509—Tapping equipment
    • F27D3/1536—Devices for plugging tap holes, e.g. plugs stoppers
    • 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
    • F27D9/00—Cooling of furnaces or of charges therein
    • 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
    • C21C5/56—Manufacture of steel by other methods
    • C21C5/567—Manufacture of steel by other methods operating in a continuous way
    • 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
    • F27D9/00—Cooling of furnaces or of charges therein
    • F27D2009/0002—Cooling of furnaces
    • F27D2009/0018—Cooling of furnaces the cooling medium passing through a pattern of tubes
    • 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

  • the present invention relates to a steel making furnace using electrical current as a heat source and, more particularly, to such a furnace designed and constructed to remain statically positioned through
  • the furnace has an electrically conductive furnace bottom, the bottom forms part of an electrical circuit powered by direct current.
  • the furnace has a non-conductive
  • the electrical circuit is powered by alternating current and the circuit is limited to the electrodes and metal charge.
  • Induction furnaces are also used to heat a metal charge by using either inductors according to a transformer principle where
  • the secondary winding is formed by a loop of liquid metal in a refractory channel or a coreless principle where induction coils surround the furnace wall and generate a magnetic field to impart energy to the metal charge in the furnace.
  • the present invention is applicable to such electric furnaces and in particular to an alternating current direct arc electric furnace equipped with three electrodes powered by three phase alternating current to establish arcs passed from an electrode to a metal charge to another electrode and from electrode to electrode.
  • the direct-arc electric-furnace as used in the steel industry is primarily a scrap-melting furnace, although molten blast-furnace iron and direct-reduction iron (DRI) are also used for charging the furnace. Combinations of scrap and minor quantities of blast furnace iron or direct reduction iron are common furnace charging compositions.
  • a three-phase transformer, equipped for varying the secondary voltage, is used to supply electrical energy at suitable range of power levels and voltages.
  • Cylindrical solid graphite electrodes are suspended by a mechanism from above the furnace downwardly through ports in a furnace roof to positions so that the electrodes conduct the electric current inside the furnace to maintain arcs for melting and refining a furnace charge.
  • a side wall supports the roof on a lower shell which is provided with a refractory lining to contain the metal charge.
  • the lower shell is pivotally support on a foundation and a furnace tilting drive is operated to tilt the furnace in each of opposite directions for de-slagging and tapping.
  • Other drive mechanisms are provided to remove the roof from the upper shell to gain access to the furnace interior for the introduction of a metal charge.
  • the tonnage of liquid metal that can be refined in such tilting furnaces is limited by the load bearing capacity of the pivotal support and the furnace tilting drive and the practical limits of the geometry of the hearth.
  • the pivotal support and the tilting drive must take the form of robust structures to sustain and pivot the weight of the entire furnace and its content of liquid steel and slag.
  • the geometry of the hearth when tilting the furnace to tap steel and to clear the tap gate for sand cleaning of the tap hole adds stresses to the pivotal support and tilting drive that increase significantly with an increase to the furnace tilt angle.
  • the tilting of the furnace must be sufficiently slow and carefully controlled to avoid erratic eccentric loading on the tilting mechanism due to the wave like shock loading as the liquid steel shifts back and forth in the volume of the hearth of the furnace.
  • the drive mechanism and support structure to tilt the electric furnace represents a significant capital expenditure. Costs are also incurred by the required maintenance to prevent a serious consequence should the tilt structure fail to allow draining of the heat from a furnace.
  • the practical limits of the geometry of a tilting furnace hearth limit the depth of steel above the tap hole and therefore limit the maximum diameter of the tap hole that can be used and still have slag free tapping. This small size tap hole results in longer tapping times. Draining most of the steel from the furnace prolongs the time between tapping of the furnace because of the need to reestablish a liquid metal bath using significant quantities of electric power for the heating the metal charge. It is known in the art to retain a quantity of the steel in the furnace after tapping which is commonly called a wet heel practice.
  • the structural integrity of the furnace mandates that the slag line be inspected periodically, typically every three to twelves heats with repairs performed based on the slag line condition. Generally, gunning will be performed several times a week. Periodically, every two-three weeks, the complete furnace bottom will be exchanged with a newly rebuilt bottom and worn bottom will have its side walls in the slag line area undergo a major repair.
  • It is another object of the present invention relates to a steel making method and furnace construction to improve electric furnace operating efficiency and
  • an electric furnace for steel making including the combination of a lower furnace
  • the lower furnace shell having a liquid metal capacity to maintain a liquid metal heel of at least 70% of a heat before tapping for flat bath refining of a heat throughout the charging and heating of a heat, an upper
  • furnace shell supported by the lower furnace shell, a furnace roof supported by the
  • a lower shell stationarily supported during furnace operations consisting of charging, heating and tapping of a heat, the lower shell having a floor with a sloping contour to increase liquid metal depth at a
  • an upper shell supported by the lower shell, a roof supported by the upper shell, the roof including at least one
  • an electrode positioned by electrode carrier arm relative to the aperture for heating a
  • the present invention also provides a method for
  • the method of including the steps of providing an electric furnace including a furnace shell having a sloping floor extending
  • Figure 1 is a front view of an electric arc furnace installation
  • Figure 2 is a plan view of the electric arc furnace installation shown in Figure 1;
  • Figure 3 is a side elevational view of the electric arc furnace illustrated in Figure 1 ;
  • Figure 4 is a sectional view taken along lines IN-IN of Figure 3;
  • Figure 5 is a side elevational view similar to Figure 3 and illustrating
  • Figure 6 is a fragmentary view similar to Figure 5 illustrating
  • Figure 7 is an elevational view of electric arc furnace transfer car
  • Figure 8 is a plan view taken along lines NIII-NIII of Figure 3;
  • Figure 9 is a sectional view taken along lines IX-IX of Figure 8.
  • Figure 10 is a fragmentary elevational view taken along lines X-X of Figure 8 showing furnace position structure
  • Figure 11 is a plan view of the structure shown in Figure 11 ;
  • Figure 12 is a sectional view taken along lines XII-XII of Figure 8.
  • Figure 13 is a sectional view taken along lines XIII-XIII of Figure 8.
  • Figure 14 is a plan view of a modified location of a tap hole in the lower shell of the furnace shown in Figure 1;
  • Figure 15 is a sectional view taken along lines XN-XN of Figure 14.
  • Figure 16 is a furnace cycle comparison between a tilting electric arc furnace and an electric arc furnace according to the present invention.
  • Figure 17 is a time comparison between tapping a tilting electric arc furnace and tapping an electric arc furnace according to the present invention.
  • Figure 18 is a side elevational view similar to Figure 3 and illustrating the addition of a pouring tundish for introducing a charge of liquid metal in the electric arc furnace;
  • Figure 19 is a plan view of a lower shell according the a second embodiment of the present invention.
  • Figure 20 is a sectional view taken along lines XX-XX of Figure 19;
  • Figure 21 is a sectional view taken along lines XXI-XXI of Figure 19;
  • Figure 22 is a sectional view taken along lines XXII-XXII of Figure
  • Figure 23 is a sectional view taken along lines XXIII-XXIII of Figure
  • the installation includes an electric arc furnace 10
  • the furnace roof 16 includes roof panels formed by an array of side-by-side coolant pipes 20 with the coolant passageways communicating with annular upper and lower
  • the service lines 28 include a flexible section 30 to avoid the need to disconnect the service lines 28 when it is desired to lift the furnace roof alone or combined with the upper furnace shell a short distance, e.g., 24 inches, for servicing the lower shell.
  • the upper water supply header 22 encircles a triangular array of three apertures 32, 34 and 36 in a roof insert 38. The apertures are dimensional and arranged to accept the phase A, B and C electrodes 40, 42 and 44 and supported by electrode support arms 46, 48 and 50, respectively.
  • Each of the electrode support arms 46, 48 and 50 is independently positioned vertically by a support post 52 restrained by horizontally spaced guides 54 in a superstructure for vertical displacement by actuator 56 typical in the form of piston and cylinder assembly.
  • the electrode support arms 46, 48 and 50 support water cooled cables for transmission of electrical current from transformers in a transformer vault 58 to the respective phase A, B and C electrodes.
  • a fume duct 60 extends vertically from an annular opening in the furnace roof between the upper and lower water supply headers 22 and 24 for exhausting fumes from the interior of the furnace to an enlarged and vertically spaced duct and overlying duct 62 formed by water coolant piping to provide thermal protection.
  • the duct 62 supplies the exhaust fume to an evaporator chamber and filter equipment, not shown, to recover pollutants.
  • the lower peripheral surface of the lower water supply header 24 of the furnace roof 16 bears on a circular ring 64 at the upper edge of the upper furnace shell 14 forming a load bearing surface to support the roof 16.
  • Vertically extended lugs 66 at annular spaced apart intervals form lateral roof restraints for maintaining the desired superimposed relation of the furnace roof on the furnace upper shell 14.
  • the furnace upper shell includes superimposed convolutions of coolant pipe 68 supplied with coolant from spaced apart supply headers 68 A and 68B that are inter connected by vertical distribution pipes 68C to form a water circulating system communicating with service lines 68D containing water supply and return lines.
  • Metal panels may be supported by the coolant pipe 20 of the furnace roof and the coolant pipe 68 of the furnace upper shell for confinement of the fume to the interiors of these furnace components.
  • the service lines 68D include a flexible section 68E to avoid the need to disconnect the service lines 68D when it is desired to lift the furnace roof combined with the upper furnace shell a short distance, e.g., 24 inches, for servicing the lower shell.
  • the convolutions of coolant pipe 68 are interrupted by a scrap charge opening 70 in one quadrant and a slag discharge opening 72 as shown in Figure 9 in an adjacent quadrant of the annular configuration of the furnace upper shell 14.
  • the scrap charge opening 70 is used to continuously introduce quantities of scrap at closely spaced apart intervals throughout the major portion of the furnace operating cycle and the scrap residing in a retractable chute 74 of a scrap charger 76 serves as a media to prevent unwanted escape of the fume from the furnace in the scrap charger.
  • a bunker 78 is used in the preferred embodiment to supply scrap to the scrap charger 76. It is within the scope of the present invention to introduce scrap to the furnace chamber using alternative well known charging equipment.
  • the slag discharge opening 72 is extended outwardly from the coolant pipe 68 boarding the slag opening by an inverted "U" shaped arrangement of barrier walls 80 formed by a serpentine arrangement of coolant pipes.
  • a slag door 82 is supported by side rails 84 mounted on the coolant pipe 68 form a movable closure for a slag discharge trough 86 in the refractory lining of the lower furnace shell 12.
  • the slag door 82 is joined by control rods to actuator discs 88 which are rotated in a conventional manner to raise the slag door 82 and allow the discharge of slag from the furnace by trough 86 beyond a threshold formed by a carbon rod insert 90 which is supported by suitable brackets 92 on the lower furnace shell 12.
  • the upper furnace shell 14 include a circular ring 94 forming a lower boundary to the shell except where a gap exists at the slag discharge opening 86. Apertures in the circular ring 94 are provided at annular spaced locations to receive upstanding locator pins 96 on annular segments at opposite lateral sides of the lower furnace shell 12. These annular ring segments are discontinuous at the slag discharge trough 86 and at a bottom crescent-shaped section protruding in an eccentric fashion from the annular configuration of the overlying upper furnace shell 14.
  • the crescent-shaped bottom section is enclosed by a correspondingly shaped crescent roof section 98.
  • the crescent-shaped roof is formed by a layer of coolant pipes.
  • the crescent-shaped bottom section is used to provide eccentric furnace tapping and is combined with the construction and operation of the lower furnace shell to achieve the benefits of flat bath operation and slag free tapping.
  • annular side wall section 100 in an area bounded by a diameter 102 with a radius Rl struck from the center of the diameter 102.
  • annular vertical side wall section 100 is bounded by a spherically-dished floor wall section 104 defined by a radius R2 struck form a point along a line defined by intersecting vertical planes 106 and 108 containing the center of the diameter 102. Plane 108 coincides
  • a floor wall section 110 begins at vertical plane 108 and
  • liquid heel line 116 formed by the upper surface of the steel heat and represents a reduction to the liquid metal depth at the diameter 102 typically slightly less than one-
  • the furnace of the present invention is operated in a manner
  • the tap hole assembly is formed by a superimposed stack of ceramic disks 124 mounted by a refractory sleeve in the
  • a truncated conical tap hole configuration and a correspondingly shaped stopper assembly may be provided according to the disclosure by German Patent No.198 26 085.
  • one of two tap hole stopper assemblies 128 A and 128B is
  • stopper assemblies 128 A and 128B enable a quick change over from one assembly to the other as needed.
  • assemblies 128 A and 128B each include a desired quantity of sand in a cardboard
  • the sleeve 130 is lowered by a chain drive 132 mounted on a platform which is pivotal between an inoperative position and an operative positioned established by a
  • an emergency tap hole closure mechanism 138 as shown in Figure 9 includes a lever arm 140 with a tap hole
  • closure plug 142 at one end and opposite thereto the arm is supported by a pivot shaft 144 secured to spaced apart brackets carried by the outer wall of the lower shell 12.
  • a piston and cylinder assembly 146 is a clevis mounted to the outer wall of the shell for pivotally displacing the closure mechanism 138 from a stand by position to a closure position. In the closure position, closure plug 142 seals off the tap hole with a sufficient force exerted by the piston and cylinder assembly to maintain the seal against the ferrostatic head.
  • the electric arc furnace 10 is statically supported continuously throughout repeated charging and tapping of heats and this feature of the present invention is utilized to maintain the central vertical axis 120 of the tap hole constant by the provision of furnace locator guide assemblies 148, 150, 152 and 154 which confine horizontal movement of the lower shell due to thermal expansions to only within vertical planes that intersect at the site of the central vertical axis 120 of the tap hole.
  • the provision of the furnace locator guide assemblies maintains the tap hole at the same location so that the underlying ladle 126 receives taped heats repeatedly at the same location.
  • the furnace locator guide assemblies also allow the cardboard sleeve 130 to be reliably lowered into the metal bath consistently along the central vertical axis 120 of the tap hole.
  • the furnace locator guide assemblies 148, 150, 152 and 154 each embody the same construction of parts which as shown in Figures 10 and 11 include a vertically arranged beam 156 secured to a lower shell 12 with a rectangular shoe plate 158 fitted for only linear sliding movement in a gap between spaced apart guide bars 160.
  • the guide bars 160 for each furnace locator guide assembly are secured to a support beam 162 forming part of a furnace support frame 164.
  • the furnace locator guide assemblies 148 and 150 cooperate to confine thermal expansion of the lower furnace shell 12 to the transverse vertical plane 122 by allowing only linear sliding movement of the rectangular shoe plates 158 between the
  • the furnace locator guide assemblies 152 are configured to guide the transverse vertical plane 122 which passes through the central vertical axis 120 of the tap hole.
  • the furnace locator guide assemblies 152 are configured to guide the furnace locator guide assemblies 152 along the transverse vertical plane 122 which passes through the central vertical axis 120 of the tap hole.
  • thermal changes to the lower furnace shell take place without altering the site of the central vertical axis of the tap hole.
  • An important feature of the present invention resides in the maintenance of a large heel after tapping a heat to facilitate the flat bath and slag free
  • Control elements for the operation of the furnace include the provision of a load cell 166 at each of a load transfer support site for the
  • embodiment of the present invention forms part of a furnace transfer car 168.
  • the support relationship between the lower furnace shell and the furnace car is shown in
  • FIG. 1-3 includes struts 170 joined to a vertical side wall of the lower shell.
  • the strut is in load bearing contact with a load cell 166 mounted on the support beam 162 extending diagonally between side beams and end beams comprising the furnace
  • the furnace transfer carl 68 is supported by wheels 172 for movement in a direction parallel to vertical plane 106 upon spaced apart rails 174 between a furnace operating position 176 as shown in Figures 2 and 3 and a furnace
  • a winch 180 is provided with a cable 182 extending between spaced apart pulleys 184 and the ends of the cable connected to the end beams of the furnace support frame 164. As shown in Figure 7, the furnace car is
  • spaced apart foundations that have an extended height that is sufficient to allow passage of a ladle 126 by a transfer car.
  • furnace roof and upper furnace shell The downtime of the furnace is an important economic factor and to minimize the downtime, the furnace roof is provided with
  • the lower furnace shell is provided with lifting lugs 192 at spaced apart intervals about the upper periphery thereof.
  • the lower furnace shell is provided with lifting lugs 194 secured to the upper parts of the struts 170.
  • drive 198 is operated to lift the upper furnace shell 14 and the furnace roof 16 as a unit and a distance sufficient to allow movement of the furnace transfer car 168 and lower furnace shell 12 from the operating position 176 to the furnace component exchange position 178. It is typical to lift these components of an electric arc furnace constructed to produce a 360T heat at the start for tapping a distance of about 2.0 feet.
  • the furnace transfer car is then returned to the operating position 176 by operation of the winch 180.
  • the rachet binders 188 are then used to draw the car against the stop 186.
  • furnace shell and furnace roof can then be lowered for support on the lower furnace shell.
  • the electrodes 40, 42 and 44 and retractable chutes 74 are the placed in their
  • furnace shell must be serviced, then only the furnace roof 16 is lifted the same
  • furnace roof and the upper shell and/or the lower shell require service, then the entire furnace is transferred by the furnace transfer car to the furnace component exchange position 178 and a reassembled furnace on the furnace transfer car is returned to the
  • furnace operating position 176 These usages of the furnace transfer car allow the use of mill cranes to transfer large furnace components without obstruction due to
  • Figures 14 and 15 illustrate a modified arrangement of a tap hole for the electric arc furnace featuring eccentric furnace tapping described and shown in
  • a tap hole insert 200 includes ceramic disks arranged in a face to face relation and mounted in the vertical side wall
  • the electric arc furnace of the present invention offers versatility to the steel making operation.
  • the furnace charging material for the most common steel making operation will be scrap which is preferable continuously introduced at closely
  • furnace with scrap, direct reduction iron may be introduced to an opening 210, shown in Figure 2, in the roof insert 38 by a chute 212 extending from a DRI storage hopper 214 as best shown in Figure 18.
  • the chute 212 is arranged at an angular relation to
  • Openings 216 are used to insert carbon/oxygen lances, not shown, for slag foaming operation. Openings 218 communicate with
  • Liquid metal may also form a furnace charge or a part thereof. Typically, the liquid metal will comprise blast furnace iron. As shown in Figure 18
  • a pouring tundish 224 with wheels arranged for supporting the tundish on the rails 174.
  • the tundish includes a launder 226 arranged to allow the
  • a ladle 228 is moved to the furnace exchange area 178 for introducing liquid metal to the tundish.
  • FIGS. 16 and 17 illustrate a cycle time comparison between a standard tilting electric arc furnace and an electric arc furnace according to the present invention. The study demonstrates a time savings of 10 minutes 20 seconds per furnace cycle. There are two factors
  • the one factor is the size of the liquid metal heel provided by the configuration of the liquid metal cavity in the refractory of the lower
  • the heel after tapping is at least 70% preferably 100% of the heat before tapping which provides a substantial thermal benefit after tapping to maintain flat bath operation throughout the charging of scrap and/or other forms for charging material as identified
  • control 167 typically located in an operator pulpit
  • the weight of the liquid metal heat may be displayed in any convenient way such as a numerical read out 167R. The read out will be used to calculate the weight of the liquid metal heat.
  • control the furnace operation including start and stop of charging and tapping.
  • the size of a heel provides the further benefit of prolonging the life of the refractory by reducing the magnitude of the temperature fluctuations of the refractory
  • This tapping operation is accomplished with the aid of a ferrostatic head of at least 3 times the tap hole diameter at the end of a tap formed by the large ferrostatic head of 180 tons of liquid metal remaining in the furnace at the
  • inches of ferrostatic head guarantees slag free tapping even with a worn tap hole.
  • Sanding of the tap hole consumes only 5 seconds.
  • the tap hole can be
  • the thermal inertia provided by the liquid metal hot heel to the refining process is sufficient in the present invention when the heel is 70% of the heat at
  • Reduction of the furnace cycle time reduces the time the hot metal stream of the tapped heat can entrain nitrogen and also reduces the time the tapped heat spends in the ladle
  • the present invention is applied to a furnace having a wholly circular vertical side wall section in a lower shell 234.
  • the configuration is shown in Figures 19-23.
  • annular side wall section 236 in an area bounded by a diameter 238 with a radius R3 struck from the center of the diameter 102.
  • the annular vertical side wall section 238 is bounded by a spherically-dished floor wall section 240 defined by a radius R4 struck form a point along a line defined by intersecting vertical planes 106 and 108 containing the center of the diameter 102.
  • Plane 108 coincides with diameter 102 and plane 106 forms a plane of symmetry of the configuration to the lower furnace shell.
  • a floor wall section 242 begins at vertical plane 108 and proceeds away from the spherically-dished floor wall section 104 by a linear downward-sloping contour along plane 106 and an ever increasing radius RN of curvature transverse to plane 106 forming a rolled developed plate floor wall configuration.
  • the ever increasing radius of transverse curvature of the floor wall section 242 results in an ever increasing height to the vertical side wall 244 as can be seen by from Figures 23 and 24.
  • the vertical side walls 238 and 244 forms a vertical boundary to the liquid metal surface commonly called a hot metal line 114 at the start of tapping a heat.
  • liquid heel line 116 formed by the upper surface of the steel heat and represents a reduction to the liquid metal depth at the diameter 102 typically slightly less than one-half of the depth of the steel heat than at the start of tapping.
  • the downwardly sloping contour of floor wall section 242 along plane 106 and the increasing shallow curvature transverse to plane 106 forms a dramatic increase to the depth liquid heel line 116.
  • the vertical side wall 244 is of maximum height and merges with floor wall section 242 along plane 106 at the site of a tap hole assembly 200.
  • the tap hole is constructed and arranged as shown and described in Figures 14 and 15.
  • the furnace of the present invention is operated in a manner to always maintain a liquid heel depth overlying the tap hole, at the end of tapping, of at least three times the diameter of the tap hole during the useful life the tap hole ceramic discs.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)

Abstract

Un four électrique comprend une enceinte inférieure fixe comportant un plancher incliné s'étendant vers le bas jusqu'à un trou de coulée de manière à toujours maintenir une tête ferrostatique suffisante d'une dimension équivalent à trois fois le trou de coulée pour assurer une sortie sans scories. La configuration du matériau réfractaire utilisé pour contenir une chaude est suffisante pour maintenir un fond de réservoir de métal liquide au moins égal à 70 % de la chaude avant le soutirage afin de continuer à fonctionner dans des conditions de bain plat pendant l'affinage de la fonte d'acier. Une enceinte de four supérieure est supportée sur l'enceinte de four inférieure et un plafond de four est supporté par l'enceinte de four supérieure. Le four tout entier est installé sur un chariot de transfert de four qui est fixé au sol pour un fonctionnement fixe mais déplacé à un endroit d'échange du four pour réparer et entretenir un des constituants du four. Le plafond du four et/ou l'enceinte du four supérieure peut/peuvent être supportés en position de fonctionnement du four alors que l'enceinte du four inférieure est transportée à un endroit d'échange du four.
PCT/IB2002/004243 2002-10-15 2002-10-15 Four electrique pour la production d'acier WO2004036131A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IB2002/004243 WO2004036131A1 (fr) 2002-10-15 2002-10-15 Four electrique pour la production d'acier

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Application Number Priority Date Filing Date Title
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2360282A1 (fr) * 2010-02-15 2011-08-24 SMS Siemag Aktiengesellschaft Four à arc électrique
DE102011075003B3 (de) 2011-04-29 2012-08-30 Siemens Aktiengesellschaft Elektroschmelzofen
US20140352494A1 (en) * 2013-06-03 2014-12-04 Midrex Technologies, Inc. Methods and systems for producing ferro-chrome in a duplex furnace

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4423514A (en) * 1981-01-20 1983-12-27 Clesid S. A. Continuously fed electric furnace for melting scrap iron
US4523747A (en) * 1983-06-15 1985-06-18 Mannesmann Ag Discharging molten metal from a smelting furnace
EP0652292A1 (fr) * 1993-11-08 1995-05-10 MANNESMANN Aktiengesellschaft Four à arc électrique à courant continu
JPH09264522A (ja) * 1996-03-27 1997-10-07 Hitachi Zosen Corp 灰溶融炉
US20020071473A1 (en) * 2000-12-13 2002-06-13 Stercho Michael J. Electric furnace for steel making
EP1239249A2 (fr) * 2001-03-09 2002-09-11 SMS Demag AG Méthode et dispositif pour fermer et percer le trou de coulée d'un récipient métallurgique, notamment d'un four de fusion électrique

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4423514A (en) * 1981-01-20 1983-12-27 Clesid S. A. Continuously fed electric furnace for melting scrap iron
US4523747A (en) * 1983-06-15 1985-06-18 Mannesmann Ag Discharging molten metal from a smelting furnace
EP0652292A1 (fr) * 1993-11-08 1995-05-10 MANNESMANN Aktiengesellschaft Four à arc électrique à courant continu
JPH09264522A (ja) * 1996-03-27 1997-10-07 Hitachi Zosen Corp 灰溶融炉
US20020071473A1 (en) * 2000-12-13 2002-06-13 Stercho Michael J. Electric furnace for steel making
EP1239249A2 (fr) * 2001-03-09 2002-09-11 SMS Demag AG Méthode et dispositif pour fermer et percer le trou de coulée d'un récipient métallurgique, notamment d'un four de fusion électrique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 02 30 January 1998 (1998-01-30) *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2360282A1 (fr) * 2010-02-15 2011-08-24 SMS Siemag Aktiengesellschaft Four à arc électrique
DE102011075003B3 (de) 2011-04-29 2012-08-30 Siemens Aktiengesellschaft Elektroschmelzofen
WO2012146466A1 (fr) * 2011-04-29 2012-11-01 Siemens Aktiengesellschaft Four électrique à arc
DE102011075003C5 (de) * 2011-04-29 2017-06-01 Primetals Technologies Germany Gmbh Elektroschmelzofen
US20140352494A1 (en) * 2013-06-03 2014-12-04 Midrex Technologies, Inc. Methods and systems for producing ferro-chrome in a duplex furnace
US9695492B2 (en) * 2013-06-03 2017-07-04 Midrex Technologies, Inc. Methods and systems for producing ferro-chrome in a duplex furnace

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