US3818112A - Electrical furnace for melting glass - Google Patents

Electrical furnace for melting glass Download PDF

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Publication number
US3818112A
US3818112A US00355877A US35587773A US3818112A US 3818112 A US3818112 A US 3818112A US 00355877 A US00355877 A US 00355877A US 35587773 A US35587773 A US 35587773A US 3818112 A US3818112 A US 3818112A
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United States
Prior art keywords
electrodes
furnace
side walls
glass
current
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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 - Lifetime
Application number
US00355877A
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English (en)
Inventor
C Snook
T Clishem
F Duerr
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.)
Saint Gobain Ceramics and Plastics Inc
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Corhart Refractories Corp
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 Corhart Refractories Corp filed Critical Corhart Refractories Corp
Priority to US00355877A priority Critical patent/US3818112A/en
Priority to CA188,092A priority patent/CA1007686A/en
Priority to GB1790174A priority patent/GB1466159A/en
Priority to FR7414665A priority patent/FR2227706B1/fr
Priority to JP49047488A priority patent/JPS5013939A/ja
Priority to NL7405742A priority patent/NL7405742A/xx
Priority to DE2420749A priority patent/DE2420749A1/de
Priority to IT22134/74A priority patent/IT1010289B/it
Priority to BE143802A priority patent/BE814414A/xx
Application granted granted Critical
Publication of US3818112A publication Critical patent/US3818112A/en
Anticipated expiration legal-status Critical
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/167—Means for preventing damage to equipment, e.g. by molten glass, hot gases, batches
    • C03B5/1677—Means for preventing damage to equipment, e.g. by molten glass, hot gases, batches by use of electrochemically protection means, e.g. passivation of electrodes
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/02—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating
    • C03B5/027—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating by passing an electric current between electrodes immersed in the glass bath, i.e. by direct resistance heating
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/12—Regulating voltage or current wherein the variable actually regulated by the final control device is ac
    • G05F1/40—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices
    • G05F1/44—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices semiconductor devices only
    • G05F1/445—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices semiconductor devices only being transistors in series with the load
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/12—Regulating voltage or current wherein the variable actually regulated by the final control device is ac
    • G05F1/40—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices
    • G05F1/44—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices semiconductor devices only
    • G05F1/45—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices semiconductor devices only being controlled rectifiers in series with the load
    • G05F1/455—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices semiconductor devices only being controlled rectifiers in series with the load with phase control
    • 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
    • H05B3/00—Ohmic-resistance heating
    • H05B3/0019—Circuit arrangements
    • H05B3/0023—Circuit arrangements for heating by passing the current directly across the material to be heated
    • 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S65/00—Glass manufacturing
    • Y10S65/04—Electric heat

Definitions

  • An electrical furnace particularly suitable for melting thermoplastic material used in producing glass fibers includes a tank having side walls constructed of a refractory material having an electrical conductivity greater than the material being melted at furnace melting temperature.
  • first and second sets of electrodes are arranged with one set centrally disposed in the tank and the other set surrounding the first. Electric power is applied between the first and second electrodes to generate a potential field with substantially continuous equi-potential lines between the second electrodes so as to shield the first electrodes from the side walls.
  • An electrical control circuit limits the current flow between any two electrodes to prevent a runaway condition which might otherwise be caused by the steep negative temperature-resistivity characteristics of the glass.
  • the control circuit includes a circuit which minimizes the DC component from current flow between the electrodes.
  • This invention relates to an electrical furnace and the method of operating this furnace to melt thermoplastic material suitable for production of glass fibers.
  • Glass produced in quantity is usually melted in a regenerative furnace fired with oil, natural gas, or other liquid or gaseous fuel.
  • the glass is contained in a tank which is usually a rectangular bath constructed of refractory blocks.
  • the fire is contained in a gas space above the tank.
  • the material fed to the tank is called batch" which is the heterogenous mixture of raw substances which when degased and fused together make the glass.
  • the batch commonly contains a modest amount of cullet which is glass that has been melted before and is now being used over again.
  • thermoplastic material which is melted as a preliminary step in the production of glass fibers is commonly referred to as E glass.
  • a typical composition of E glass is:
  • E glass has a very steep negative temperature resistivity characteristic.
  • Most glasses have such a negative temperature coefficient.
  • borosilicate glass sold under the trademark Pyrex and common soda-lime-silica glass both decrease in electrical resistivity as the temperature increases.
  • the decrease in resistivity with temperature is relatively small.
  • E glass exhibits a markedly larger decreasein resistivity. Because of this, there tend to be runaway" paths between electrodes in an electrical furnace. A slight increase in current flowing directly between the electrodes increases the heating along this path. Therefore the resistance of the E glass decreases along this path resulting in an even more increased current flow along the path.
  • the effect is cumulative producing the runaway path between the electrodes whereas of course it is desirable to distribute current flow in predetennined regions of the batch.
  • Cornelius shows a row of electrodes along one side wall, a row of electrodes in the middle and a row of electrodes on the opposing side wall. Three-phase power is applied between all three rows. Since a voltage is imposed between the two rows of electrodes along the sidewalls, current flow through relatively high conductivity sidewalls would be induced during melting E glass.
  • thermoplastic material is melted in an electric furnace with an electrode arrangement which applies a potential field (i.e., electrostatic field) to the thermoplastic material which effectively shields the sidewalls from current conduction paths.
  • a potential field i.e., electrostatic field
  • first electrodes are mounted in the center of the furnace tank.
  • Second electrodes are mounted with predetermined spacing around the inside of the periphery of the tank. Electrical power is applied between the first and the second electrodes so that a potential field is created in the thermoplastic material with equi-potential lines extending substantially continuously between the second electrodes. This effectively shields the first electrodes from the sidewalls and minimizes current flow through the sidewalls.
  • the electric power is controlled by feedback circuits which minimize the possibility of a runaway path in the thermoplastic material.
  • Such a power control circuit is provided for different sets of first and second electrodes distributed throughout the furnace. In this way a good distribution of heating current throughout the batch is obtained and the likelihood of a runaway path between any one set of electrodes is minimized.
  • the feedback circuitry includes a circuit which reduces, or eliminates, the direct current component in the applied power. It has been found that this direct current component causes undesirable polarization and blister formation in the glass, excessive heating around the electrodes and accelerated deterioation of the electrodes.
  • the control circuitry of this invention eliminates these undesirable effects.
  • FIG. I is a view along the section 11 of FIG. 2;
  • FIG. 2 is a top view of the furnace
  • FIG. 3 is a block diagram of the electrical control circuit for one set of electrodes
  • FIG. 4 is an electrical schematic diagram of one embodiment of the control circuit
  • FIG. 5 is a diagram of another embodiment of the electrical circuit
  • FIGS. 6A-6E are waveforms depicting the operation of the circuit of FIG. 5;
  • FIG. 7 shows the resistivity-temperature characteristics of three types of glass
  • FIGS. 8-l1 depict potential fields produced by various electrode arrangements in electric furnaces.
  • FIG. 12 shows typical firing sequences.
  • FIGS. 1 and 2 show an electrical furnace including a tank having sidewalls l0, 12, Hand 16 and a bottom 18. As is common in fumacesof this type a batch inlet and a glass outlet are'provided. First electrodes 20, 22
  • g and 24 are mounted in a row in the middle of the tank.
  • Second electrodes 26, 28, 30, 32, 34, 36, 38 and 40 are positioned in the bottom of the tank.
  • the spacing between the second electrodes is predetermined and the second'electrodes are positioned around the inside periphery of the tank between the first electrodes and the sidewalls.
  • a batch of thermoplastic material 42 is heated bycurrent passing between the first and second electrodes.
  • the furnace is of the type particularly suitable for melting E glass for the manufacture of glass fibers.
  • FIG. 3 shows the source of electric power applied between one set of first and second electrodes to induce current flow through the glass.
  • AC power from a source which includes the transformer 44 is applied through solid state controllers 46 which are connected in series between the electrodes 24 and 32.
  • the solid state controllers are included in a single device commonly referred to as a triac.
  • a pair of silicon controlled rectifiers are used to control the current.
  • a trigger circuit 48 controls the phase angle at which each of the controllers fire during alternate half cycles of the AC power.
  • a feedbackQcircuit 50 controls the current flow between the first and second electrodes.
  • a shunt resistance 52 is connected in series with the electrodes. The voltage across this resistor is a measure of the current and is applied to the feedback circuit 50.
  • the triac controllers shown in FIG. 3 were used in model studies only but this circuit illustrates the principles of operating a furnace in accordance with this invention.
  • FIG. 4 shows one embodiment of the trigger circuit 48 and the feedback circuit 50 for the circuit of FIG. 3.
  • a feedback signal developed acrossresistor 52 is coupled through transformer 54 to the lamp 56.
  • Lamp 56 produces a light intensity which is proportional to the square of the current through the feedback resistor 52. This light impinges on the photoconductive cell 58.
  • the voltage across this photocell 58 is proportional to the mean square value of the current through the resistor 52.
  • the triggering circuit includes a capacitor 60 and a unijunction transistor 62.
  • the capacitor 60 is charged by the voltage across the control device 46.
  • the transistor 62 conducts.
  • a pulse of current passes through the primary of pulse transformer 64.
  • the secondary is coupled to the gate of the control device 46 and triggers this device.
  • the voltage across the control device 46 is rectified in a full wave rectifier including the diodes 66, 68, and 72. Zener diodes 74 and 76 clip peaks or excursions in the'voltage.
  • the feedback circuit adds a bias voltage to the voltage applied to capacitor 60. Instead of starting atzero, the charging voltage starts at the feedback levelsupplied by the photoconductor 58.
  • the control action is as follows. Assume that the current through the feedback resistor is above the desired regulated value.
  • the feedback signal applied to lamp 56 increases the-light intensity and this decreases the resistance of photocell 58. Therefore, the initial bias .voltage applied to the capacitor 60 decreases. There'- fore, it takes longer in the half cycle for thecapacitor 60 to charge to the firing voltage of the unijunction transistor 62. Therefore, the control device 46 fires later in the half cycle and the current supplied to the electrodes is decreased. 1
  • Typical component values for a circuit of this type can be obtained from the General Electric Transistor Manual.-
  • FIG. 5 An alternate embodiment using silicon controlled rectifiers is shown in FIG. 5.
  • Back to back SCRs 80 and 82 are connected between the AC power source and the electrodes.
  • Two control loops are used to provide regulation.
  • the control loop 84 regulates the rms value of load current.
  • the control loop 86 regulates the DC component of the current between the two electrodes.
  • the signal from the feedback resistor which is in series with the electrodes is applied to amplifier 88.
  • the feedback signal is summed in summing amplifier 90 with the signal representing the desired levelof AC current. This is obtained from the mean square current reference potentiometer the output of which is applied to the reference signal amplifier 91.
  • the output of summing amplifier 90 is applied to a photomodulator 92 which may be similar to that previously described. This produces a signal proportional to rms current through the feedback resistor.
  • a control amplifier 94 acts through gating circuits 96 and 98 to control the conduction angle of the SCRs 80 and 82 thereby regulating the AC current between the electrodes and maintaining it at a desired value set by an input potentiometer.
  • the other control loop 86 determines whether there is a deviation of the DC current component from the desired zero level.
  • the feedback signal from amplifier 88 is rectified in rectifier 100 and integrated in integrator 102.
  • the same feedback signal is inverted in inverter 104, rectified in rectifier 106 and integrated in integrator 103.
  • the difference between the outputs of integrators 102 and 103 is a measure of the DC component in the signal.
  • the outputs of integrators 102 and 103 are applied to differential amplifier l 10.
  • the resultant signal is applied to control amplifier 112.
  • a zero adjustment of the DC component is made by the DC reference potentiometer 114.
  • the output of control amplifier 112 acts through the summing amplifier 116 to control the firing angle of the silicon control rectifier 82.
  • the firing angle of SCR 82 is advanced or delayed to return the DC component to zero.
  • FIGS. 6A-6E The waveforms of the FIG. 5 circuit are shown in the FIGS. 6A-6E.
  • FIG. 6A shows the AC input voltage
  • FIG. 6B shows the voltage across the load
  • FIG. 6C shows the voltage across the SCRs.
  • the gating pulses applied to the SCRs are shown in FIGS. 6D and 6E.
  • FIG. 7 shows the steep resistivity-temperature characteristic of E glass as compared to a common borosilicate glass and a common soda-lime-silica glass. Because of the very sharp reduction in resistivity for a given increase in temperature, E glass is particularly susceptible to runaway current paths during electrical heating. However, by providing a plurality of current controllers each controlling the current through a given set of electrodes, the current can be well distributed in the E glass without danger of runaway.
  • FIG. 8 depicts the equi-potential lines of potential field formed by a voltage applied between two electrodes at the bottom and the common electrode at the top. Current flow is transverse to the equi-potential lines. Note that there is a path between the two electrodes at the bottom whereby current can flow-to the side wall and through the side wall.
  • FIG. 9 depicts the shielding effect which is obtained when the two bottom electrodes are moved closer together. This arrangement is less susceptible to current flow through the sidewalls.
  • FIG. 10 shows the electrostatic field formed when three common electrodes are arranged in a row in the middle and surrounded by eight electrodes to which the opposite polarity voltage is applied. The shielding effect is good.
  • FIG. ll depicts the effect of high conducting sidewalls on the potential field of FIG. 10. The shielding effect is still good.
  • the applied voltage and the number and spacing of the electrodes can be varied to provide most effective shielding for different size tanks.
  • the equi-potential lines for any given arrangement can be plotted by using modeling techniques. Optimum operation will be achieved by producing a potential field such as that shown in FIG. 11, or a potential field with even more continuous equi-potential line extending between the outer electrodes.
  • the furnace side walls were constructed of refractory brick commercially available from the Corhart Refractories Company with the designation C-1 215.
  • This refractory has a resistivity at l,500C of about 1 ohm centimeter.
  • the resistivity of the E glass at l,500C is about 24 ohm centimeter, very much greater than that of the sidewalls.
  • the furnace bottom is constructed of a zircon material commercially available from Corhart Refractories Company and identified as ZS-l300. It has a resistivity at l,500 of about 3,400 ohmcentimeters and does not significantly contribute to overall refractory conduction.
  • Electrodes are Tl 185 tin oxide electrodes commercially available from Corhart Refractories Company.
  • the controlled voltage input between each set of electrodes is 180-200 volts AC, single phase 60 Hz.
  • the output current is regulated to plus or minus 1 percent for load currents of 20 amps to 200 amps.
  • Silcenter electrodes and surrounding electrodes, and in some cases for sometime thereafter e.g. until the molten glass pool reaches refining temperature approximately l,500 C. for E glass).
  • This system can also be used in a booster type operation wherein thermal energy is supplied by both electricity and fuel.
  • FIGS. l2A-l2F Typical firing combinations between the electrodes are shown in FIGS. l2A-l2F. Other combinations can be used.
  • the controllers can also be connected to control the power applied to the center electrodes instead of the outer electrodes as shown.
  • furnace tank might be divided into individual, controllable zones and using a different phase of a multiple phase power supply for each zone.
  • the furnace might be divided into three zones with each zone having an electrode configuration similar to that shown in FIG. 2.
  • One phase of a three phase power supply could be applied to the center electrodes of each zone with the outer electrodes common.
  • zone control can be accomplished either by sequentially switching the inner electrodes or the outer electrodes.
  • the degree of shielding remains substantially constant over the entire electrical cycle.
  • thermoplastic material comprising:
  • H I a plurality of current controllers, one for each set of electrodes, each current controller controlling the current through a given set of electrodes.
  • thermoplastic material comprising:
  • At least one first vertical electrode disposed between said side walls in said tank
  • second vertical electrode means disposed about said w slsstrqsisaan V.
  • said power supply includes solid state power controllers connected in series between an AC power supply and one of said electrodes, and i a triggering circuit for controlling the phase angle at which said solid state controllers fire during each half cycle of said AC source, said feedback circuit being connected to said triggering circuit to control said phase angle.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Electromagnetism (AREA)
  • Physics & Mathematics (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Furnace Details (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Control Of Resistance Heating (AREA)
  • Glass Melting And Manufacturing (AREA)
US00355877A 1973-04-30 1973-04-30 Electrical furnace for melting glass Expired - Lifetime US3818112A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US00355877A US3818112A (en) 1973-04-30 1973-04-30 Electrical furnace for melting glass
CA188,092A CA1007686A (en) 1973-04-30 1973-12-13 Electrical furnace for melting glass
GB1790174A GB1466159A (en) 1973-04-30 1974-04-24 Electrical furnace
JP49047488A JPS5013939A (it) 1973-04-30 1974-04-26
FR7414665A FR2227706B1 (it) 1973-04-30 1974-04-26
NL7405742A NL7405742A (it) 1973-04-30 1974-04-29
DE2420749A DE2420749A1 (de) 1973-04-30 1974-04-29 Elektroofen
IT22134/74A IT1010289B (it) 1973-04-30 1974-04-30 Forno elettrico
BE143802A BE814414A (fr) 1973-04-30 1974-04-30 Four electrique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00355877A US3818112A (en) 1973-04-30 1973-04-30 Electrical furnace for melting glass

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US3818112A true US3818112A (en) 1974-06-18

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US00355877A Expired - Lifetime US3818112A (en) 1973-04-30 1973-04-30 Electrical furnace for melting glass

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US (1) US3818112A (it)
JP (1) JPS5013939A (it)
BE (1) BE814414A (it)
CA (1) CA1007686A (it)
DE (1) DE2420749A1 (it)
FR (1) FR2227706B1 (it)
GB (1) GB1466159A (it)
IT (1) IT1010289B (it)
NL (1) NL7405742A (it)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0014873A1 (en) * 1979-02-19 1980-09-03 Elettromeccanica Tironi S.r.l. Method of melting vitreous materials and use of the suitable device for the accomplishment of the method
US4413346A (en) * 1981-11-04 1983-11-01 Corning Glass Works Glass-melting furnace with batch electrodes
US4421538A (en) * 1980-05-07 1983-12-20 Eglasstrek Patent Promotion & Awarding Gmbh Device for the manufacture of glass filaments
US4737966A (en) * 1987-01-12 1988-04-12 Corning Glass Works Electric melter for high electrical resistivity glass materials
US4741753A (en) * 1987-03-12 1988-05-03 Owens-Corning Fiberglas Corporation Method and apparatus for electrically heating molten glass
US20040011080A1 (en) * 2000-08-25 2004-01-22 Erich Rodek Method and device for refining glass
US20090148797A1 (en) * 2005-10-24 2009-06-11 L'air Liquide Societe Anonyme Pour L'etude Et Exloitation Des Procedes Georges Claude Method for Carrying Out combined Burning in a Recovering Furnace
CN101407368B (zh) * 2008-10-23 2011-02-02 黎国琪 一种烧制琉璃件的专用电窑及控制方法
US11565960B2 (en) * 2016-11-08 2023-01-31 Corning Incorporated Apparatus and method for forming a glass article

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3967046A (en) * 1975-02-18 1976-06-29 Owens-Corning Fiberglas Corporation Apparatus and method for increasing furnace life in an electric furnace for thermoplastic materials
JP2023091397A (ja) * 2021-12-20 2023-06-30 日本電気硝子株式会社 ガラス物品の製造方法及びガラス物品の製造装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3395237A (en) * 1967-05-03 1968-07-30 Harold S. Orton Electric resistance furnace

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3395237A (en) * 1967-05-03 1968-07-30 Harold S. Orton Electric resistance furnace

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0014873A1 (en) * 1979-02-19 1980-09-03 Elettromeccanica Tironi S.r.l. Method of melting vitreous materials and use of the suitable device for the accomplishment of the method
US4412334A (en) * 1979-02-19 1983-10-25 Elettromeccanica Tironi S.R.L. Method of melting vitreous materials and use of the suitable device for the accomplishment of the method
US4421538A (en) * 1980-05-07 1983-12-20 Eglasstrek Patent Promotion & Awarding Gmbh Device for the manufacture of glass filaments
US4413346A (en) * 1981-11-04 1983-11-01 Corning Glass Works Glass-melting furnace with batch electrodes
EP0275174A1 (en) * 1987-01-12 1988-07-20 Corning Glass Works Electric melter for high electrical resistivity glass materials
US4737966A (en) * 1987-01-12 1988-04-12 Corning Glass Works Electric melter for high electrical resistivity glass materials
US4741753A (en) * 1987-03-12 1988-05-03 Owens-Corning Fiberglas Corporation Method and apparatus for electrically heating molten glass
US20040011080A1 (en) * 2000-08-25 2004-01-22 Erich Rodek Method and device for refining glass
US20070266737A1 (en) * 2000-08-25 2007-11-22 Playtex Procucts, Inc. Method and a device for the refining of glass
US7694533B2 (en) * 2000-08-25 2010-04-13 Schott Glas Method for the refining of glass
US20100147031A1 (en) * 2000-08-25 2010-06-17 Schott Glas Method and a device for the refining of glass
US8869561B2 (en) 2000-08-25 2014-10-28 Schott Ag Method and a device for the refining of glass
US20090148797A1 (en) * 2005-10-24 2009-06-11 L'air Liquide Societe Anonyme Pour L'etude Et Exloitation Des Procedes Georges Claude Method for Carrying Out combined Burning in a Recovering Furnace
CN101407368B (zh) * 2008-10-23 2011-02-02 黎国琪 一种烧制琉璃件的专用电窑及控制方法
US11565960B2 (en) * 2016-11-08 2023-01-31 Corning Incorporated Apparatus and method for forming a glass article

Also Published As

Publication number Publication date
FR2227706B1 (it) 1978-01-20
BE814414A (fr) 1974-10-30
GB1466159A (en) 1977-03-02
IT1010289B (it) 1977-01-10
CA1007686A (en) 1977-03-29
DE2420749A1 (de) 1974-11-21
JPS5013939A (it) 1975-02-13
NL7405742A (it) 1974-11-01
FR2227706A1 (it) 1974-11-22

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