US20060219052A1 - Method and a device for detecting slag - Google Patents

Method and a device for detecting slag Download PDF

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Publication number
US20060219052A1
US20060219052A1 US10/560,089 US56008904A US2006219052A1 US 20060219052 A1 US20060219052 A1 US 20060219052A1 US 56008904 A US56008904 A US 56008904A US 2006219052 A1 US2006219052 A1 US 2006219052A1
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United States
Prior art keywords
shroud
molten metal
coil
flow
forked
Prior art date
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Abandoned
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US10/560,089
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English (en)
Inventor
Mats Jalk
Willy Ohlsson
Håkan Kelvesjö
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MPC Metal Process Control AB
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MPC Metal Process Control AB
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Assigned to MPC METAL PROCESS CONTROL AB reassignment MPC METAL PROCESS CONTROL AB ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: JALK, MATS, KELVESJO, HAKAN, OHLSSON, WILLY
Publication of US20060219052A1 publication Critical patent/US20060219052A1/en
Abandoned legal-status Critical Current

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    • 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
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/4673—Measuring and sampling devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D2/00—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
    • B22D11/186—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by using electric, magnetic, sonic or ultrasonic means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D2/00—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass
    • B22D2/001—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass for the slag appearance in a molten metal stream
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D37/00—Controlling or regulating the pouring of molten metal from a casting melt-holding vessel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D37/00—Controlling or regulating the pouring of molten metal from a casting melt-holding vessel
    • B22D37/005—Shielding the molten metal stream
    • 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
    • F27D19/00—Arrangements of controlling devices
    • 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
    • F27D21/00—Arrangements of monitoring devices; Arrangements of safety devices
    • F27D21/0028—Devices for monitoring the level of the melt
    • 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
    • F27D3/145—Runners 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
    • F27D3/15—Tapping equipment; Equipment for removing or retaining slag
    • F27D3/1545—Equipment for removing or retaining slag
    • F27D3/159—Equipment for removing or retaining slag for retaining slag during the pouring of the metal or retaining metal during the pouring of the slag
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
    • G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
    • G01N27/9013—Arrangements for scanning
    • G01N27/9026—Arrangements for scanning by moving the material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20—Metals
    • G01N33/205—Metals in liquid state, e.g. molten metals
    • 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
    • C21C2005/5288—Measuring or sampling devices
    • 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
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0084—Controlling closure systems, e.g. doors
    • 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 method and a device for detecting slag in a flow of molten metal.
  • the invention relates to detecting the presence of slag by means of an electromagnetic field which is propagated through the molten metal.
  • the invention also relates to a casting plant comprising such a device.
  • liquid metal is to be processed in one way or another.
  • One example is the casting of metal, such as steel.
  • the liquid metal is supplied from a ladle to a tundish via a pouring nozzle which is generally referred to as a shroud.
  • the metal flows from the tundish via another pouring nozzle to a casting mould or chill mould, in which the metal is cooled and transformed into solid form.
  • the casting plant may include a slag detection device. If the slag detection device detects slag in the molten metal an alarm is generated so that suitable measures may be taken.
  • one type of slag detection device includes electromagnetic coils placed above a sliding gate in the ladle. This type of slag detection device works on the principle that for an electromagnetic field the penetration depth of metal is much less than the penetration depth of slag. Thus, a large portion of the electromagnetic field is allowed to pass through slag, similarly to air.
  • the prior art detecting device generally provides satisfactory detecting results, it has some drawbacks.
  • One drawback is that every ladle used in a casting plant has to be equipped with the electromagnetic coils, the coils being welded to the ladle. Furthermore, the coils installed in a ladle are in such a position where there is a relatively high risk of mechanically damaging the sensors. Thus, it would be desirable to install electromagnetic slag detecting sensors (coils) in such manner that cuts costs and minimizes the risk of mechanical damage to the sensors.
  • An object of the present invention is to achieve a method, a device and a casting plant which alleviate the drawbacks of the prior art.
  • the invention is based on the insight that by optimising the constancy of the propagation of an electromagnetic field through a flow of molten metal, it is possible to, in contrast to the prior art, move the electromagnetic slag detection out of the ladle.
  • the molten metal to be subjected to a positionally constant electromagnetic field, it is even possible to perform the slag detection at such location which moves as the molten metal passes said location.
  • a shroud which guides molten metal from the ladle to a tundish can be subjected to electromagnetic slag detection, in a simple and economical manner, despite the movements of the shroud. Movement of the shroud may occur during the pouring of the molten metal. Such movement may be linear or in arcs of a circle. The shroud also tends to move when the sliding gate at the ladle is moved.
  • a transmitting coil is used for generating an electromagnetic field which enters the channel and its contents.
  • a receiving coil is used to receive the electromagnetic field that has entered the channel and its contents.
  • the electromagnetic field generates an induced voltage in the receiving coil.
  • the value of the induced voltage e.g. if it is outside or within a defined voltage range, is indicative of the presence or absence of slag in said contents.
  • the electromagnetic field generated by the transmitting coil(s) is arranged to enter a shroud and its contents, the shroud being the above-mentioned channel for guiding molten metal, in particular from a ladle to a tundish.
  • the transmitting and receiving coils are kept substantially unmovable relative to the shroud.
  • a device for detecting slag in line with the above mentioned method According to a second aspect of the invention, there is provided a device for detecting slag in line with the above mentioned method.
  • the transmitting coil and the receiving coil are suitably held in place by either a common or separate coil holders.
  • a common coil holder may be designed in the form of a fork having at least two branches.
  • the transmitting coil and the receiving coil may then be held by respective branches adapted to be placed on respective sides of the shroud.
  • the forked coil holder may either stand by itself or be connected to other equipments as will be explained below.
  • the coils are kept unmovable relative to the shroud. If the coils are unmovable relative to the shroud, i.e. they follow any movement of the shroud, an even signal is obtained for an unchanged flow of molten metal.
  • This may be accomplished by e.g. mounting the transmitting coil and the receiving coil to respective branches of a forked coil holder mentioned above.
  • the forked coil holder is suitably placed in such manner that an imagined straight line drawn between the transmitting coil and the receiving coil crosses the shroud. In other words the shroud is placed between the branches of the forked coil holder.
  • An advantage of using a forked coil holder is that it is possible to use a relatively long stem thereof, wherein positioning of the coils around the shroud can be accomplished by manoeuvring at a distance from the shroud without having to access the shroud closely.
  • the branches of the forked coil holder facilitate correct positioning of the coils and reduces the risk of relative movements between the coils thereby avoiding unnecessary erroneous signal variations. The risk of relative movements between the coils are further reduced if the branches are made relatively short.
  • a relatively long stem having short branches may suitably be used. Since the forked coil holder, preferably, does not entirely surround the circumference of the shroud it is easily locatable to and removable from the shroud.
  • the forked coil holder is suitably suspended to an arrangement that follows the movements of the shroud.
  • a shroud manipulator of any known type.
  • a shroud manipulator is. generally in the form of an elongate arm that is used to fetch, position and support the shroud.
  • Such a shroud manipulator may comprise a holder portion, e.g. in the form of a ring or horse shoe, in which the shroud is suspended.
  • the shroud manipulator may also comprise a gripping means, e.g.
  • the gripping means is generally attached to an arm which may be automatically or manually controlled.
  • a shroud manipulator arm is usually connected to a unit which can make the arm move vertically, horizontally and in rotational movement. This is advantageous since the shroud manipulator is used for fetching a shroud from a location spaced from the tundish.
  • the shroud is moved from said location by means of the shroud manipulator which has been rotated for achieving the inclination of the shroud.
  • the inclined shroud can thereby be brought into the space between the ladle and the tundish, and by rotating the shroud manipulator arm the shroud can be brought into a fully vertical position and the shroud is placed against the outlet of the ladle.
  • the shroud may be kept in place by pressing the shroud manipulator upwardly.
  • the ladle may be raised or lowered, thereby causing the shroud to move relative to the shroud manipulator in the vertical plane of the extension of the shroud manipulator. This change of ladle position is generally not carried out when the relevant slag detection is to be performed at the end of the emptying of the ladle.
  • the forked coil holder may thus be mounted to such a shroud manipulator.
  • the forked coil holder may be suspended to the sliding gate unit mounted on the ladle, and other alternatives are also possible in order to achieve the desired motion following effect.
  • the coil holder is placed on a manipulator, in particular a shroud manipulator, the coils being unmovable relative to the shroud at least in a horizontal direction perpendicular to the extension of the shroud manipulator.
  • the third aspect of the invention provides a method of detecting the presence of slag in a shroud for guiding molten metal from a ladle to a tundish, the method comprising: providing a forked coil holder having at least two branches; mounting at least one transmitting coil to a first branch and at least one receiving coil to a second branch of the forked coil holder; mounting said forked coil holder to a shroud manipulator adapted to manipulate the shroud; placing the forked coil holder in such manner that an imagined straight line drawn between the transmitting coil and the receiving coil crosses the shroud; generating, by means of said transmitting coil, an electromagnetic field that enters the shroud and its contents; generating an induced voltage by means of said receiving coil which is subjected to the electromagnetic field having entered the channel and its contents, wherein said induced voltage is indicative of the presence or absence of slag in said contents; and keeping the coils unmovable relative to the shroud.
  • the forked coil holder may be mounted to the shroud manipulator when the manipulator has already located the shroud in place between the ladle and the tundish.
  • the forked coil holder may be mounted to the shroud manipulator before the manipulator has arranged the shroud into correct position, or even at a point in time when the shroud has not yet been connected to the shroud manipulator.
  • the forked coil holder is suitably connected to an arm of the shroud manipulator.
  • the advantage of a method according to the third aspect of the invention is i.a. that it is place-saving, since use is made of the shroud manipulator as a carrier for the coils or the coil holder.
  • Another advantage is that the coils may be arranged in a fix relation to the shroud, due to their fix relation to the shroud manipulator which during casting holds the shroud.
  • the shroud manipulator is also included in a device or system according to a fourth aspect of the invention.
  • a device for detecting the presence of slag in a shroud for guiding molten metal from a ladle to a tundish, comprising: at least one transmitting coil for generating an electromagnetic field to be entered into the shroud and its contents; at least one receiving coil for receiving the electromagnetic field that has entered the shroud and its contents, and for generating an induced voltage, wherein said induced voltage is indicative of the presence or absence of slag in said contents; a shroud manipulator adapted to manipulate the shroud; a forked coil holder mounted to the shroud manipulator and having at least two branches, a first branch carrying said at least one transmitting coil and a second branch carrying said at least one receiving coil, the two branches being placeable in such manner that the shroud is located between them and that said at least one transmitting coil and said at least one receiving coil are in a stationary
  • the two branches that hold the transmitting coil and the receiving coil respectively may in at least one embodiment of the invention be electrically isolated from one another. If for example the branches are connected to the stem by means of a common cross bar, that bar may be provided with electrical isolation. This type of interruption minimizes unwanted electromagnetic fields.
  • the method according to the first aspect of the present invention could also be carried out by arranging the coils on separate holding elements, e.g. separate arms, that are electrically isolated from one another.
  • Such separate holding elements may also be mounted to the shroud manipulator or other shroud motion following arrangement. Accordingly, there are different ways in which to generate an electromagnetic field by means of one or more transmitting coils from one side of the shroud and to receive said electromagnetic field by means of one or more receiving coils on another side of the shroud.
  • each coil is arranged to surround the shroud.
  • the coils may be given a toroid or annular form and the shroud will extend through each toroid.
  • the coils may be mounted to the shroud by means of a coil holder arrangement including fasteners for securing the coils to the shroud.
  • the annular configuration can be mounted to some other location, such as the sliding gate at the ladle, and be suspended therefrom so as to surround the shroud.
  • Another alternative is to mount the coils between the branches of a forked coil holder which in turn is mounted to a shroud manipulator or other shroud following arrangement.
  • the voltage induced by the receiving coil(s) is used to determine whether or not slag or slag is present.
  • any induced voltage having a value outside a defined voltage range is indicative of the presence of slag.
  • the flow of molten metal passing through the shroud is determined and the voltage range is defined depending on the magnitude of the determined flow of molten metal. The advantage of this is that the detection of slag in the shroud may be even more accurate.
  • a shroud is not necessarily completely filled with molten metal at all times. Since gas and slag have similar influence or lack of influence on the electromagnetic field, some gas in the shroud could be taken for slag.
  • an alarm limit is set depending on the amount of gas (e.g. air) present.
  • the embodiment is based on the insight that the presence of gas can be determined by determining the flow, i.e. the volume per unit of time, of molten metal passing through the shroud.
  • the advantage of determining the flow of molten metal is that it provides a ratio of the flow components, i.e. the amount of metal to the amount of gas in the shroud, wherein depending on a change in said ratio the sensitivity of the detection device may be varied. For instance, if the flow of molten metal decreases after a while, the requirement for or level of providing an alarm of the detection device is increased. This is done by increasing said defined voltage range. This means that a given induced voltage may be either indicative of the presence of slag or not depending on the presently defined voltage range.
  • a given induced voltage value may fall outside a voltage range defined before a decrease of the flow, which would result in an indication of presence of slag and on the other hand, after the decrease of the flow and the increase of the voltage range, the same value of induced voltage would be covered by the redefined voltage range, wherein it would be construed as presence of gas, if any, and not slag.
  • the risk of slag being entrained in the flow of molten metal usually increases towards the end of the process, when the ladle is close to being drained.
  • the variation of voltage range may be illustrated in the following way.
  • the receiving coil for an empty shroud, i.e. just gas and no molten metal, generates an induced voltage having a signal strength V 1 .
  • V 1 When molten metal passing through the shroud completely fills up the shroud a voltage having a signal strength V 2 will be induced, wherein V 2 ⁇ V 1 .
  • the voltage range is set to at least the interval 0-V 2 , however, in order to be on the safe side and not risk a false alarm, the voltage range may be extended somewhat.
  • the definition of the voltage range is suitably adjusted.
  • the newly defined voltage range will be 0-V 3 , wherein V 2 ⁇ V 3 ⁇ V 1 .
  • the voltage range is defined such that the presence of slag is indicated if the value of the induced voltage corresponds to a metal content of 45% or less. Note that the numbers in the this example are merely exemplifying in order to illustrate a general principle of varying the voltage range.
  • the flow of molten metal guided through the shroud may be determined either directly or indirectly. Different types of flow meters may be employed for direct measurement of the flow inside the shroud. However, it may be simpler to make use of an indirect method of determination. For instance, the flow of molten metal passing through the shroud may be determined by measuring the teeming rate in the tundish and calculating the flow of molten metal from said measured teeming rate. Another alternative is to measure the rate of decrease in weight of the ladle content and calculating the flow of molten metal from said measured rate of decrease in weight. Yet another alternative is to measure the casting speed and the dimension of the cast product after the chill mould, the speed and dimension being indicative of the flow.
  • a further alternative is to detect the degree of opening or the position of the sliding gate mounted under the ladle and to provide a feedback signal to a processor, which calculates the flow of molten metal from the positional information of the sliding gate, i.e. how much the siding gate has been opened.
  • the frequency of the electromagnetic field generated by the transmitting coil may be controlled. It has been found that a higher frequency provides a more stable induced voltage signal when the shroud is not completely filled and a turbulent flow of molten metal is present inside the shroud. Thus, when a turbulent flow inside the shroud has been detected, the frequency of the electromagnetic field is changed, suitably increased, by the system. Also, the magnitude of the flow of molten metal influences the chosen frequency in order to penetrate the metal and detect any slag in the centre of or at any other place if the flow of molten metal. External frequencies that can interfere with the measurement can be a ground for changing the frequency.
  • the electromagnetic field generated by the transmitting coils(s) may be of alternating frequencies. Also, several coils may be used for generating several electromagnetic fields, each with a different frequency, in order to minimise noise effects. Furthermore, several coils may be used for generating several electromagnetic fields, one or more being of alternating frequencies.
  • the transmitting coil that generates the electromagnetic field may be provided with directional elements, such as a core, for optimised direction of the electromagnetic field towards the portion of the shroud in which it is intended to check whether or not slag is present.
  • the receiving coil may be provided with such directional elements.
  • the transmitting and receiving coils may be cooled by means of a suitable cooling arrangement, such as cooling channels containing water or gas.
  • a device for detecting the presence of slag in a shroud which guides molten metal from a ladle to a tundish comprising a forked coil holder having at least two branches, a first branch carrying a transmitting coil and a second branch carrying a receiving coil, the two branches being placeable in such manner that the shroud is located between them.
  • a casting plant which comprises a ladle, a tundish and a shroud between them.
  • the casting plant also comprises a device for detecting the presence of slag inside the shroud, as has been previously described in this application.
  • FIG. 1 is a schematic illustration of a device arranged to detect slag in a shroud in accordance with at least one embodiment of the invention.
  • FIG. 2 is a more detailed schematic illustration of the components shown around the shroud in FIG. 1 .
  • FIG. 3 is a flow chart illustrating an example of an operation of a control unit.
  • FIG. 1 schematically illustrates a ladle 2 adapted to contain molten metal which is to be passed through a shroud 4 over to a tundish 6 .
  • the metal flows from the tundish 6 via a pouring nozzle to a chill mould, in which the metal is cooled and transformed into solid form, the pouring nozzle and the chill mould not being shown in the figure.
  • a forked coil holder 10 is provided at the outside of the shroud 4 and is mounted to a shroud manipulator 30 .
  • the forked coil holder 10 contains a transmitting coil for generating an electromagnetic field to be propagated through the shroud and to be received by a receiving coil which is also located in the forked coil holder 10 .
  • the forked coil holder 10 and the coils will be further described in connection with the discussion of FIG. 2 .
  • a signal cable 40 extends between the forked coil holder 10 and a connector 42 .
  • the signal cable 40 contains internal cables or separate wires for leading signals to and from the transmitting coil and the receiving coil, respectively.
  • Also connected to the connector 42 are a transmitter signal cable 44 and a receiver signal cable 46 containing wires for providing signals to and from the transmitting coil and the receiving coil, respectively.
  • the receiver signal cable 46 is at its other end connected to a preamplifier unit 48 in order to amplify generated induced voltage signals from the receiving coil.
  • a preamplifier cable 50 passes on the signals to a control unit 52 which comprises a processor.
  • the transmitter signal cable 44 is directly connected to the control unit 52 . The generation of an electromagnetic field by the transmitting coil can thus be controlled by sending a signal from the control unit 52 , via the transmitter signal cable 44 , the connector 42 and the associated wires in the signal cable 40 to the transmitting coil inside the forked coil holder 10 .
  • the control unit 52 is connected to an alarm unit 54 via an alarm cable 56 .
  • the control unit 52 compares the received induced voltage signal from the receiving coil with a predefined voltage range. If the received voltage is not included in said voltage range, the control unit 52 activates the alarm unit 54 , which may suitably generate an acoustic and/or visual alarm. Also, even though not shown, a control panel may be provided for enabling continuous visual monitoring of the slag detection process.
  • control unit 52 receives information about the flow, i.e. the volume per unit of time of molten metal through the shroud. This piece of information is received over a flow input line 58 which at its other end is connected to a flow determining device (not shown), which can be either a direct measuring device or an indirect measuring device with subsequent calculation, as previously explained. If it is determined that a significant change in flow of molten metal has occurred, the control unit 52 will set a different voltage range. A decreased flow results in the setting of a larger voltage range and an increased flow results in the setting of a narrower voltage range. Thus, the point at which the alarm unit 54 is activated is dependent on the received flow information.
  • FIG. 2 is a partly cut away perspective view.
  • the forked coil holder 10 comprises a stem portion 12 , a first branch portion 14 , a second branch portion 16 and a cross bar portion 18 .
  • the branch portions 14 , 16 are located at opposite ends of the cross bar portion 18 and the stem portion 12 is connected to the middle of the cross bar portion 18 .
  • the stem portion could be placed at one end of the cross bar portion and even be an elongation of one of the branch portions.
  • FIG. 2 illustrates that the interior of the first branch portion 14 comprises at its end farthest from the cross bar portion 18 a transmitting coil 20 .
  • the wires 22 of the transmitting coil are passed through the first branch portion 14 , via the cross bar portion 18 and the base portion 12 to the control unit (see also FIG. 1 ).
  • FIG. 2 also illustrates that the interior of the second branch portion 16 comprises at its end farthest from the cross bar portion 18 a receiving coil 24 .
  • the wires 26 of the receiving coil 24 are passed through the second branch portion 16 , via the cross bar portion 18 and the base portion 12 to the control unit (see also FIG. 1 ).
  • the ends of the branches portions 14 , 16 are so positioned that the transmitting coil 20 , the shroud 4 and the receiving coil 24 are located in a straight line. In other words, the shroud 4 is located between the two coils 20 , 24 .
  • the branch portions 14 , 16 , or sections thereof, may be controllable between different anales relative to the rest of the forked coil holder. This enables the coils 20 , 24 to be correctly positioned for setting the main direction of propagation of the electromagnetic field at a right angle to the shroud in working position.
  • the wires of the two coils 20 , 24 may be electrically isolated from one another in the cross bar portion 18 and the stem portion 12 in order to avoid unwanted electromagnetic influence on any signals.
  • the forked coil holder 10 is suitably made of mainly nonmagnetic material, such as any one of stainless steel, ceramic material, fibre glass or other similar suitable material that substantially does not interfere with the electromagnetic field.
  • the forked coil holder 10 is suspended to the shroud manipulator 30 by means of a clamping arrangement 32 comprising two protrusions 34 each of them having at its end a clamp 36 surrounding the shroud manipulator 30 .
  • the clamps 36 are tightened to the shroud manipulator 30 by means of bolts or screws 38 .
  • the shroud manipulator 30 illustrated in FIG. 2 is of standard type and comprises at the end portion that holds the shroud 4 a gripping means.
  • the gripping means comprises two grip portions 62 that are inclined upwards from the rear elongate portion 64 of the shroud manipulator 30 . The inclination depends among other things on how the shroud is to be positioned. The initial gripping point on the shroud differ from the shroud positioning point of the manipulator, making it desirable to change the angle.
  • the grip portions 62 are further connected to a holder 66 shaped as a horse shoe.
  • FIG. 3 is a flow chart illustrating an example of an operation of the control unit 52 shown in FIG. 1 .
  • a step S 1 the control unit defines a voltage range.
  • the control unit receives a signal indicative of the voltage induced at the receiving coil.
  • the control unit compares the value of the received signal with the defined voltage range and determines whether or not said value is within the defined voltage range. If said value is not within the defined voltage range (in such a case the absolute value of the received signal is generally larger then the absolute value of the maximum voltage of the voltage range), then the control unit activates a slag detection alarm in a step S 4 . If on the other hand it is determined in step S 3 that the value of the received signal is encompassed by the defined voltage range, the control unit returns to step S 2 to receive a new signal to be compared in the subsequent step S 3 etc.
  • control unit In parallel to said steps, the control unit also receives a flow signal in a step S 5 .
  • the flow signal is indicative of the volume per unit of time of molten metal flowing through the shroud.
  • control unit compares the determined flow of molten metal with stored values and examines whether or not there has been a significant change of flow over time. If there has been no significant change the control unit continues with the step S 5 to examine subsequent flow signals. However, if there is a significant change, the control unit will in accordance with the stored values (such as a table) redefine the voltage range in the step S 1 .
  • FIG. 3 is only an example of the operation of the control unit for elucidating purposes and that other alternatives are also possible.

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US10/560,089 2003-06-13 2004-06-07 Method and a device for detecting slag Abandoned US20060219052A1 (en)

Applications Claiming Priority (3)

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EP0301291.4 2003-06-13
EP03013291A EP1486271B1 (de) 2003-06-13 2003-06-13 Verfahren und Vorrichtung zum Erkennen von Schlacken
PCT/EP2004/006108 WO2004110676A1 (en) 2003-06-13 2004-06-07 A method and a device for detecting slag

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EP (1) EP1486271B1 (de)
JP (1) JP2006527089A (de)
KR (1) KR20060028410A (de)
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Cited By (3)

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Publication number Priority date Publication date Assignee Title
US20100158429A1 (en) * 2008-12-03 2010-06-24 Massachusetts Institute Of Technology Resonant optical modulators
CN106541091A (zh) * 2016-06-06 2017-03-29 湖南科美达电气股份有限公司 一种传感器
CN111562589A (zh) * 2020-04-20 2020-08-21 国网浙江省电力有限公司电力科学研究院 一种电站锅炉水冷壁结渣程度的监视方法

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DE102008008033A1 (de) * 2007-08-04 2009-02-05 Sms Demag Ag Einrichtung zum schlackenfreien Abstich oder zur Überführung einer Schmelze
AT506190B1 (de) 2007-12-20 2010-05-15 Siemens Vai Metals Tech Gmbh Vorrichtung zum auswechselbaren anschliessen eines giessrohres an einen ausguss eines schmelzenbehälters
JP6398413B2 (ja) * 2014-07-18 2018-10-03 新日鐵住金株式会社 取鍋からのスラグ流出検知方法及びスラグ流出抑制方法
WO2023073955A1 (ja) 2021-10-29 2023-05-04 日本製鉄株式会社 流量測定システム

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DE3142681A1 (de) * 1981-10-24 1983-05-05 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Wirbelstrommesseinrichtung fuer stranggiessanlagen
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US4816758A (en) * 1984-10-27 1989-03-28 Amepa Angewandte Messtechnik Und Prozessautomatisierung Gmbh Method and apparatus for the detection of slag co-flowing within a stream of molten metal
US6539805B2 (en) * 1994-07-19 2003-04-01 Vesuvius Crucible Company Liquid metal flow condition detection
US5549280A (en) * 1995-06-06 1996-08-27 Vesuvius Crucible Company Probe system for reliably monitoring a condition in a metallurgical process
US6737014B2 (en) * 2000-03-17 2004-05-18 Nupro Corporation Slag detector for molten steel transfer operations
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100158429A1 (en) * 2008-12-03 2010-06-24 Massachusetts Institute Of Technology Resonant optical modulators
CN106541091A (zh) * 2016-06-06 2017-03-29 湖南科美达电气股份有限公司 一种传感器
CN111562589A (zh) * 2020-04-20 2020-08-21 国网浙江省电力有限公司电力科学研究院 一种电站锅炉水冷壁结渣程度的监视方法

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WO2004110676A1 (en) 2004-12-23
EP1486271B1 (de) 2008-07-16
CA2528226A1 (en) 2004-12-23
EP1486271A1 (de) 2004-12-15
JP2006527089A (ja) 2006-11-30
ATE401152T1 (de) 2008-08-15
DE60322193D1 (de) 2008-08-28
KR20060028410A (ko) 2006-03-29

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