EP0121111B1 - Verfahren zur Steuerung der Leistung eines Rinneninduktors - Google Patents

Verfahren zur Steuerung der Leistung eines Rinneninduktors Download PDF

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Publication number
EP0121111B1
EP0121111B1 EP84102212A EP84102212A EP0121111B1 EP 0121111 B1 EP0121111 B1 EP 0121111B1 EP 84102212 A EP84102212 A EP 84102212A EP 84102212 A EP84102212 A EP 84102212A EP 0121111 B1 EP0121111 B1 EP 0121111B1
Authority
EP
European Patent Office
Prior art keywords
power
inductor
tundish
pinching
channel
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP84102212A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0121111A1 (de
Inventor
Kare Ing. Folgerö
Sten Dipl.-Ing. Kollberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Norden Holding AB
Original Assignee
ASEA AB
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 ASEA AB filed Critical ASEA AB
Publication of EP0121111A1 publication Critical patent/EP0121111A1/de
Application granted granted Critical
Publication of EP0121111B1 publication Critical patent/EP0121111B1/de
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/16—Furnaces having endless cores
    • H05B6/20—Furnaces having endless cores having melting channel only
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/06—Control, e.g. of temperature, of power
    • H05B6/067—Control, e.g. of temperature, of power for melting furnaces
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/34—Arrangements for circulation of melts

Definitions

  • the invention relates to a method for controlling the performance of a channel inductor.
  • a pan or intermediate pan is often preheated before it is put into operation, for example to about 1000 degrees C, but usually not higher, since it would otherwise be necessary to use oxygen-enriched air, which would be expensive and would result in additional wear on the lining.
  • the temperature during steel casting or heating would drop from approx. 1500 degrees C to a lower temperature, which is why one would like to increase the power supply from the start of casting or heating.
  • the possibility of this is limited by the pinch effect, especially when there is a low static pressure in the inductor channel.
  • an intermediate pan for continuous casting (tundish) is not preheated to a temperature higher than approx. 1000 degrees C, and the temperature drop mentioned takes place at the beginning of the pouring process.
  • the pinch effect easily occurs due to the low static pressure, which leads to the risk of arcing, lining wear and other damage.
  • a preferred embodiment of the invention relates to the control of the power of an inductor connected to a tundish for continuous casting.
  • the power of the inductor is also reduced at the beginning of the pouring process when the static pressure in the tundish is low and the risk of the pinch effect occurring is high, the temperature of the melt in the pan being as uniform as possible becomes.
  • the risk of the pinch effect occurring is particularly great, and there is a risk of metal evaporation in the channel because it becomes too hot in the channel, for example when using the inductor for zinc, bronze, brass, etc.
  • the power consumption of the inductor can thus be brought to a maximum without the dangerous consequences of the occurrence of a pinch effect having to be expected.
  • a uniform temperature curve is also achieved during commissioning.
  • the pinch effect can be read in a few 50 Hz periods and a reaction is triggered when the current has dropped, for example, by 5 or 10 percent.
  • the reading and reaction take place so quickly that it usually does not happen that the secondary current becomes zero due to the pinching effect due to the pinch effect. But even if this happens, it is harmless because the response of the power down control is very quick.
  • the output is therefore reduced and then increased again to a limit above which the pinch effect would probably begin. This power down and power up can continue and follow an ideal curve that corresponds to the highest deliverable power without the pinch effect occurring.
  • the control or regulation of the power of the inductor can thus be carried out in such a way that the inductor constantly works at the limit of the pinch effect, so that the power supply is maximized with a certain predetermined induction.
  • the power supplied can be controlled by a computer.
  • the invention thus avoids poor utilization of the inductor and the occurrence of arcs and thus excessive wear on the lining. Since the level of the melt in a tundish is low, about 0.6-0.8 m, the static pressure in the melt is low, so that without the use of the invention there is a risk of the melt strand being pinched off, e.g. the appearance of the pinch effect would exist. If the current in the channel is too high, the current density increases. In such cases there is a risk of the melt being pinched off. This problem is solved by the method according to the invention.
  • the power B supplied to the inductor is first reduced (see FIG. 5) and then increased again to such an extent that it lies at or near the pinch effect limit 11 (FIG. 5).
  • the power of the inductor is reduced again and then increased again, etc., as a result of which the power P supplied to the inductor essentially follows the limit curve 11 for the occurrence of the pinch effect.
  • the dashed curve 13 shows the power requirement and the fully drawn curve 14 shows the power supplied.
  • the power supplied to the inductor is plotted on the ordinate and the time in minutes is plotted on the abscissa.
  • FIG. 4 shows the change in the pinch effect limit Pi as a function of time. If the inductor is fed by a thyristor converter, there is enough time to reduce the power so that a pinch effect is avoided. The control of the power can be carried out so that the inductor is constantly operating at the pinch effect limit, and the power supply can be maximized with a given induction.
  • the time given in the above curves always refers to the time after the start of watering in minutes.
  • the risk of the pinch effect gradually diminishing as the tundish is filled.
  • the method according to the invention allows the ideal temperature-time curve 9 in FIG. 2 to be largely approximated. Even if this is not completely successful, a broad approximation can also be achieved, as the dashed curve 10 in FIG. 2 shows. At the end of the pouring process there is a certain tendency to lower the temperature, as can be seen at 12 in FIG. However, this reduction in temperature can be easily counteracted by increasing the power of the inductor in this section of the casting process.
  • the power P of the inductor can, as shown for example in FIG. 5, follow its course over time - if one disregards the relatively faster periodic changes - after an increasing curve 15, for example a straight line, which is expediently adjustable, for example with regard to its slope. If the power P becomes greater than the setpoint power P ref , the power drops to P ref .
  • the power is reduced, for example, by 10% (adjustable value) and increased again in accordance with curve 15.
  • the pinch effect can be indicated (measured) by a sudden increase in reactive power, a sudden lower current, etc., which are easy to measure values.
  • the invention described above can be varied in many ways within the scope of the general inventive concept disclosed.
  • the invention can also be applied to other types of channel inductors, both channel channels of the normal type and those of other types, e.g. the tea-pot design, for example if it is used for continuous pouring, keeping warm, etc.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Induction Heating (AREA)
  • Continuous Casting (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
EP84102212A 1983-03-07 1984-03-02 Verfahren zur Steuerung der Leistung eines Rinneninduktors Expired EP0121111B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8301225A SE435988B (sv) 1983-03-07 1983-03-07 Anordning for styrning av effekten i en renninduktor
SE8301225 1983-03-07

Publications (2)

Publication Number Publication Date
EP0121111A1 EP0121111A1 (de) 1984-10-10
EP0121111B1 true EP0121111B1 (de) 1987-06-24

Family

ID=20350280

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84102212A Expired EP0121111B1 (de) 1983-03-07 1984-03-02 Verfahren zur Steuerung der Leistung eines Rinneninduktors

Country Status (5)

Country Link
US (1) US4594723A (sv)
EP (1) EP0121111B1 (sv)
JP (2) JPS59167989A (sv)
DE (1) DE3464453D1 (sv)
SE (1) SE435988B (sv)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61135088A (ja) * 1984-12-05 1986-06-23 富士電機株式会社 タンデイツシユの電力制御方法
JP2515898B2 (ja) * 1989-11-30 1996-07-10 ホーヤ株式会社 溶融装置
US7113535B2 (en) * 2004-05-21 2006-09-26 Ajax Tocco Magnethermic Corporation Induction furnace for melting granular materials
EP1989012A2 (en) * 2006-01-25 2008-11-12 Energetics Technologies, L.L.C. Method of axial porosity elimination and refinement of the crystalline structure of continuous ingots and castings
US9104670B2 (en) 2010-07-21 2015-08-11 Apple Inc. Customized search or acquisition of digital media assets

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2541841A (en) * 1947-06-20 1951-02-13 Ajax Engineering Corp Unidirectional flow in plurality chamber induction furnace
US2768413A (en) * 1953-04-20 1956-10-30 Allegheny Ludlum Stcel Corp System for controlling the flow of molten metal
US2937789A (en) * 1953-10-16 1960-05-24 Ajax Magnethermic Corp Controlled metal dispensing
CH461716A (de) * 1967-09-07 1968-08-31 Prolizenz Ag Verfahren zur Ingangsetzung und Aufrechterhaltung der Metallzuführung zu einer Stranggiesskokille und Vorrichtung zur Ausführung des Verfahrens
DE1954763A1 (de) * 1969-07-01 1971-02-04 Adamec Ing Alfred Verfahren zum Betrieb eines Induktors und Induktor hierfuer
SU427234A1 (ru) * 1972-03-23 1974-05-05 Дозирующее устройство токопроводящих жидкостей
SE7311938L (sv) * 1973-09-03 1975-03-04 Asea Ab
SE8008136L (sv) * 1980-11-20 1982-05-21 Asea Ab Tvakammarrennugn

Also Published As

Publication number Publication date
SE435988B (sv) 1984-10-29
SE8301225D0 (sv) 1983-03-07
JPS59167989A (ja) 1984-09-21
JPH077015Y2 (ja) 1995-02-22
US4594723A (en) 1986-06-10
DE3464453D1 (en) 1987-07-30
SE8301225L (sv) 1984-09-08
EP0121111A1 (de) 1984-10-10
JPH0619965U (ja) 1994-03-15

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