US3867563A - Refining apparatus and processes - Google Patents

Refining apparatus and processes Download PDF

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Publication number
US3867563A
US3867563A US363351A US36335173A US3867563A US 3867563 A US3867563 A US 3867563A US 363351 A US363351 A US 363351A US 36335173 A US36335173 A US 36335173A US 3867563 A US3867563 A US 3867563A
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United States
Prior art keywords
frequency
power
work coil
furnace
single work
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Expired - Lifetime
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US363351A
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English (en)
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Reginald E Laflin
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    • 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
    • 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

Definitions

  • ABSTRACT This invention relates to melting and refining apparatus and processes, and is concerned with the problem of obtaining the correct metallurgical conditions in coreless induction furnaces.
  • the invention consists in using a furnace with a single work coil connected through switching means to one or more electric power sources arranged so that the frequency applied to the single work coil can be varied.
  • the electric power may be supplied by a single variable frequency power source such as a static thyristor inverter device, or by a number of individual sources, each designed to produce electric currents alternating at a particular frequency. This arrangement enables material to be melted by supplying current to the work coil at high power and a high frequency and to be refined by using a low power and a low frequency.
  • the present invention provides a coreless induction furnace comprising a refractory lining, and a single work coil surrounding the refractory lining.
  • the single work coil is provided with first and second terminals, one at each end of the coil.
  • switching means for connecting the first and second terminals of the work coil to a selected one of the power factor capacitor units and to the output of the variable frequency electric power source.
  • the present invention also provides a coreless induction furnace comprising a refractory lining, and a single work coil surrounding the refractory lining.
  • the single work coil is provided with first and second terminals, one at each end of the work coil.
  • the apparatus also includes a plurality of power capacitor units, one associated with each of the power sources.
  • switching means for connecting the first and second terminals of the work coil to a selective one of the power sources and the associated power factor capacitor unit.
  • the present invention also provides a refining process carried out in a coreless induction furnace having a single work coil, comprising the steps of placing a charge to be melted and refined in the coreless induction furnace, supplying electric current to the single work coil at a relatively high power and a relatively high frequency to melt the charge, and supplying electric current to the single work coil at a relatively low power and a relatively low frequency to refine the melt of said charge.
  • the invention consists in a coreless induction furnace having a single work coil connected through switching means to a variable-frequency electric power source.
  • the invention consists in a coreless induction furnace having a single work coil connected through changeover switching means to a plurality of electric power sources capable of producing electric currents alternating at mutually different frequencies.
  • the invention consists in a refining process carried out in a coreless induction furnace having a single work coil, wherein a charge is melted by supplying electric current to said work coil at relatively high power and a relatively high frequency, and wherein the melt is refined by supplying electric current to said coil at a relatively low power and a relatively low frequency.
  • FIG. 1 is a block circuit diagram of a first embodiment of the invention showing a coreless induction furnace powered by a variable frequency power source.
  • FIG. 2 is a block circuit diagram of a second embodiment of the invention showing a coreless induction furnace powered by two alternative power sources.
  • FIG. 1 of the drawings shows a coreless induction furnace 1 having a refractory lining 2 and a single work coil 3 provided with terminals 4 and 5, one at each end of the coil. These terminals are connected through flexible, water cooled cables 6 to a furnace busbar system
  • Three capacitor units 8 9 and 10 are connected to the busbar system 7 through respective double pole switches ll, 12 and 13.
  • the capacitor unit 8 is suitable for use over a range of frequencies between 50 and 200 Hz.
  • the capacitor unit 9 is suitable for use over a range of frequencies between 200 and 700 I-Iz.
  • the capacitor unit 10 is suitable for a range of frequencies between 700 and 10,000 Hz.
  • the three capacitor units are connected through respective further double pole switches 14, 15 and 16 to a further busbar system 17.
  • This busbar system 17 is connected through a main contactor 18 to the output of a variable frequency power source 19 drivin from a three-phase voltage supply connected to input terminals 20.
  • the power source 19 may be, for example, a so-called static inverter which is constituted by means for rectifying the threephase input and deriving avariable frequency output from the resulting D.C. supply.
  • the switches 11 to 16 are preferably coupled to the control member for changing the frequency of the power source 19 so that the appropriate capacitor unit is automatically switched into circuit as the frequency of the power source is changed.
  • the capacitor unit 24 is suitable for use at a frequency of 500 Hz., and is connected through a pair of lines 28 to 500 Hz., power source 29.
  • This power source 29 may be constituted by a static thyristor frequency converter connected to a medium voltage, high power three-phase supply 30.
  • the power source 29 may include a rotary-type frequency converter comprising a motor driven by the three-phase suppply 30 and mechanically coupled to a single-phase, 500 Hz. generator feeding the lines 28. In this case, it will also include conventional contactors and motor starter.
  • the capacitor units 23 and 24 may be connected in series in the lines 27 and 28, respectively, or they may be connected in parallel with these lines.
  • the power factor capacitors connected either in series or in parallel between the power supply and the work coil may be changed.
  • three capacitor units may be provided in a typical installation and these units may be switched in automatically as the frequency is changed.
  • One unit may be designed to cover a low frequency range, for example, from 50 to 200 Hz, one unit for an intermediate frequency range from 200 to 700 Hz, and one for a medium frequency range from 700 to 1,000 Hz.
  • mechanical and electrical interlocks are provided to ensure that the correct capacitor unit is connected in circuit at every frequency.
  • a suitable variable-frequency electric power source may be constituted by a static inverter device operating over a range of frequencies, for example, from 50 to 10,000 Hz.
  • a variable-frequency power source is not available, some of the advantages of the invention may still be realised by using a plurality of power sources of mutually different operating frequencies (see FIG. 2).
  • the low-frequency source may, for example, operate at 50 Hz while the relatively high-frequency source operates at 500 Hz.
  • a coreless induction furnace comprising, in combination:
  • said single work coil having first and second terminals one at each end of said single work coil
  • switching means for connecting said first and second terminals to a selected one of said power factor capacitor units and to the output of said variable frequency electric power source.
  • variable-frequency electric power source is constituted by a static inverter device operating over a range of frequencies between 50 and 10,000 Hz.
  • a coreless induction furnace comprising in combination:
  • a single work coil surrounding said refractory lining; said single work coil being provided with first and second terminals, one at each end of said work coil;
  • switching means for connecting said first and second terminals to a selected one of said power sources and the associated power factor capacitor unit.
  • a furnace as claimed in claim 8 including mechanical and electrical interlocks adapted to ensure that the correct capacitor unit is connected in circuit at each operating frequency.
  • a refining process carried out in a coreless induction furnace having a single work coil comprising the steps of:

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Induction Heating (AREA)
  • Furnace Details (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US363351A 1972-05-26 1973-05-24 Refining apparatus and processes Expired - Lifetime US3867563A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2492872A GB1415504A (en) 1972-05-26 1972-05-26 Coreless induction furnace refining and melting apparatus and processes

Publications (1)

Publication Number Publication Date
US3867563A true US3867563A (en) 1975-02-18

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ID=10219503

Family Applications (1)

Application Number Title Priority Date Filing Date
US363351A Expired - Lifetime US3867563A (en) 1972-05-26 1973-05-24 Refining apparatus and processes

Country Status (9)

Country Link
US (1) US3867563A (fr)
BE (1) BE800063A (fr)
DE (1) DE2326515A1 (fr)
ES (1) ES415256A1 (fr)
FR (1) FR2189976B3 (fr)
GB (1) GB1415504A (fr)
IT (1) IT987908B (fr)
LU (1) LU67659A1 (fr)
NL (1) NL7307339A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4525665A (en) * 1982-08-06 1985-06-25 Smalley Daniel S Induction furnace monitor
US4612498A (en) * 1982-08-06 1986-09-16 Smalley Daniel S Induction furnace fault locator
US5012487A (en) * 1989-06-14 1991-04-30 Inductotherm Europe Limited Induction melting
US5216215A (en) * 1990-05-29 1993-06-01 Transflux Holdings Limited Electrically powered fluid heater including a coreless transformer and an electrically conductive jacket
US5280496A (en) * 1990-07-26 1994-01-18 Francois Schlecht Induction furnace with cooled crucible
US5789721A (en) * 1994-06-04 1998-08-04 Horiba, Ltd. High-frequency induction heater and power source circuit for same
US6163019A (en) * 1999-03-05 2000-12-19 Abb Metallurgy Resonant frequency induction furnace system using capacitive voltage division
US6414982B1 (en) * 1999-08-21 2002-07-02 Schott Glas Device for melting and/or refining inorganic compounds

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3008972C2 (de) * 1980-03-08 1984-08-30 Vorwerk & Sohn Gmbh & Co Kg, 5600 Wuppertal Notlaufring für Fahrzeug-Luftreifen

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3536983A (en) * 1967-12-12 1970-10-27 Inductotherm Corp Frequency multiplier and stirring circuit for an induction furnace

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3536983A (en) * 1967-12-12 1970-10-27 Inductotherm Corp Frequency multiplier and stirring circuit for an induction furnace

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4525665A (en) * 1982-08-06 1985-06-25 Smalley Daniel S Induction furnace monitor
US4612498A (en) * 1982-08-06 1986-09-16 Smalley Daniel S Induction furnace fault locator
US5012487A (en) * 1989-06-14 1991-04-30 Inductotherm Europe Limited Induction melting
US5216215A (en) * 1990-05-29 1993-06-01 Transflux Holdings Limited Electrically powered fluid heater including a coreless transformer and an electrically conductive jacket
US5280496A (en) * 1990-07-26 1994-01-18 Francois Schlecht Induction furnace with cooled crucible
US5789721A (en) * 1994-06-04 1998-08-04 Horiba, Ltd. High-frequency induction heater and power source circuit for same
US6163019A (en) * 1999-03-05 2000-12-19 Abb Metallurgy Resonant frequency induction furnace system using capacitive voltage division
US6414982B1 (en) * 1999-08-21 2002-07-02 Schott Glas Device for melting and/or refining inorganic compounds

Also Published As

Publication number Publication date
IT987908B (it) 1975-03-20
FR2189976A1 (fr) 1974-01-25
BE800063A (fr) 1973-09-17
DE2326515A1 (de) 1973-12-06
NL7307339A (fr) 1973-11-28
LU67659A1 (fr) 1973-07-26
GB1415504A (en) 1975-11-26
FR2189976B3 (fr) 1976-05-21
ES415256A1 (es) 1976-02-01

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