Electric furnace construction
First Claim
1. A furnace for melting thermoplastic material comprising:
- a vessel having a bottom wall and a first upstanding peripheral sidewall, liner means concentrically disposed within said vessel having an upstanding sidewall, spaced apart from said first sidewall and extending continuously from a lower portion to near an upper portion of said first sidewall for containing convection flow of said thermoplastic material therewithin and for protecting said vessel from excessive corrosion by the molten thermoplastic material, and peripherally located means partly associated with at least one of said vessel and said liner means for providing a relatively cool peripheral zone wherein the temperature of the thermoplastic material within said zone is sufficiently low so that movement thereof is minimized and corrosion of the vessel is thereby inhibited.
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Accused Products
Abstract
A method and apparatus for melting thermoplastic material is disclosed utilizing, in a preferred embodiment, a vessel having a bottom wall and upstanding sidewalls. A protective liner for the vessel is provided, being formed of corrosion resistant material. The furnace may include both through-the-batch and floor electrodes, and also hot spot fining to a conductive outlet channel.
A method is set forth for operating the furnace described herein utilizing symmetrical, below the batch heat dissipation for accelerated melting. In order to protect the liner, which in some instances may be fabricated from an oxidizable refractory metal, start-up burners are operated under a reduced oxygen supply.
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Citations
96 Claims
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1. A furnace for melting thermoplastic material comprising:
- a vessel having a bottom wall and a first upstanding peripheral sidewall, liner means concentrically disposed within said vessel having an upstanding sidewall, spaced apart from said first sidewall and extending continuously from a lower portion to near an upper portion of said first sidewall for containing convection flow of said thermoplastic material therewithin and for protecting said vessel from excessive corrosion by the molten thermoplastic material, and peripherally located means partly associated with at least one of said vessel and said liner means for providing a relatively cool peripheral zone wherein the temperature of the thermoplastic material within said zone is sufficiently low so that movement thereof is minimized and corrosion of the vessel is thereby inhibited.
- View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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2. A furnace for melting thermoplastic material having an open upper portion for receiving batch material to be melted therein comprising:
- a refractory vessel having a sidewall and bottom wall;
an oxidizable liner means positioned within the refractory vessel in close proximity with at least the sidewall of the vessel but spaced apart therefrom so as to form a relatively narrow annular space between the liner means and the sidewall;
an upper edge of the liner means being adapted to be located below the fusion line formed by said batch material to be melted and the molten thermoplastic material therebelow to protect the same from oxidation and;
the molten thermoplastic material being free to form convection currents within the liner means and at the same time being inhibited from forming convection currents within the narrow annular space whereby the liner means protects the vessel from corrosion and the molten thermoplastic material covering the linear means protects the same from oxidation. - View Dependent Claims (41, 42, 43, 44, 45)
- a refractory vessel having a sidewall and bottom wall;
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3. The furnace of claim 102 further including peripherally located means partially associated with at least one of the vessel and the liner means for providing a relatively cool zone wherein the temperature of the thermoplastic material is sufficiently low so that circulation thereof between the liner means and the annular space is minimized.
- 61. In a furnace having a relatively hot central region therein for continuously melting thermoplastic material, a vessel susceptible to corrosion by the molten thermoplastic material, a liner located within the vessel and closely conforming to but spaced apart from the interior thereof and being of a material strongly resistant to corrosion by the thermoplastic material, said liner being at least partially immersed within the thermoplastic material and being effective to protect the vessel from corrosion, passive cooling means at least at an upper extent of said vessel and said liner for shielding a portion of the molten material from heat energy of the hot central region and for rendering molten thermoplastic material within such shielded portion relatively highly viscous in comparison to the remainder of the thermoplastic material within the vessel thereby reducing convection, seepage and cross contamination of the materials on opposite sides of said liner.
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63. In a furnace for melting thermoplastic material having a zone of relatively intense heat in a central portion thereof comprising:
- a vessel having a bottom wall and a first upstanding peripheral sidewall, a liner concentrically disposed within said vessel having an upstanding sidewall spaced apart from said first sidewall and extending from a lower portion to near an upper portion of said first sidewall for containing said thermoplastic material therewithin and for protecting the vessel from excessive corrosion by the molten thermoplastic material, an upstanding electrically conductive outlet channel located through an opening in the bottom wall of the vessel, the channel having an inlet opening at a free upstanding end thereof positioned at a selected level above the bottom wall within the furnace, said inlet being positioned to receive melted thermoplastic material from said level and to convey said material to an outlet end remotely located from the inlet of said channel, and an electrically energizable electrode means mounted for positionment in spaced relation with the outlet channel, means for firing the electrode electrically with respect to the outlet channel so that relatively concentrated electrical energy flows through the molten thermoplastic material between the electrode and outlet channel.
- View Dependent Claims (64, 65)
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66. In a furnace for melting thermoplastic material, a method of protecting a refractory vessel portion of said furnace from corrosion caused by moving convection currents of the hot molten thermoplastic material contained within the vessel by providing an oxidizable liner for the interior of the vessel, and at the same time protecting the liner from oxidation from ambient oxygen comprising the steps of:
- locating the liner within the vessel in close proximity with the same for providing a relatively narrow space between the liner and vessel;
confining some of the thermoplastic material within the vessel between the liner and the vessel, the confines of the narrow space inhibiting motion of the thermoplastic material, whereby corrosion of the vessel is reduced; and
totally immersing the liner beneath the thermoplastic material for shielding the same from the ambient oxygen and thereby protecting the liner from oxidation while the liner protects the vessel. - View Dependent Claims (67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92)
- locating the liner within the vessel in close proximity with the same for providing a relatively narrow space between the liner and vessel;
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93. An operating glass-melting furnace of the type in which batch materials introduced through an opening in the upper end are melted by means of current-carrying electrodes extending into the interior of said furnace and the resulting molten glass is discharged through an opening formed in the lower end thereof, characterized in that said furnace includes a refractory bottom wall, refractory sidewalls, and a metallic liner spaced interiorly of said refractory sidewalls whereby to form an annular channel at least between said sidewalls and said metallic liner, and said metallic liner is completely immersed in and surrounded by molten glass.
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94. A furnace for melting thermoplastic material comprising;
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a refractory vessel having sidewall portions, a discharge opening formed in a lower portion of said vessel, a metallic liner positioned within said refractory vessel in close proximity with said sidewall portions but spaced apart therefrom so as to form a relatively narrow annular space between said liner and said sidewall portions, said refractory vessel having an open upper portion for receiving batch material to be melted, and electrode means for melting batch material delivered to said furnace; the upper edge of said liner being below the fusion line formed by said batch material to be melted and the molten material therebelow. - View Dependent Claims (95, 96)
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Specification