Glass manufacturing equipment

Abstract

A glass manufacturing apparatus is disclosed that includes a vessel configured to deliver molten glass and a conduit extending from the vessel, the conduit including a distal end having a concave heating element joined thereto, a first electrical flange joined to the conduit, and a second electrical flange joined to the concave heating element. A method of preventing devitrification of molten glass-forming materials is also described.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Application Serial No. 63 / 113,009, filed on November 12, 2020, the content of which is hereby incorporated by reference in its entirety.

[0002] (Technical Field) The present disclosure generally relates to glass manufacturing apparatuses, and more particularly, to glass manufacturing apparatuses for delivering a molten material such as molten glass to a glass forming apparatus.

Background Art

[0003] The glass manufacturing process can be divided into three stages: a melting step of heating raw materials to form a molten glass - forming material, a fining step of removing gaseous inclusions (e.g., bubbles) from the molten glass - forming material, and a heat conditioning step. After the heat conditioning step, the molten glass - forming material is delivered to a forming apparatus through an outlet conduit. The molten material exiting the outlet conduit should have a temperature profile that gives the molten glass - forming material an appropriate forming viscosity.

[0004] If the viscosity (e.g., temperature) of the molten glass - forming material is not properly maintained at the outlet conduit, particularly at the outlet of the outlet conduit, the molten glass - forming material may devitrify. That is, if the temperature of the molten glass - forming material falls below the devitrification temperature for a sufficient time, devitrification may occur.

Summary of the Invention

[0005] The following presents a simplified summary of the present disclosure in order to provide a basic understanding of some embodiments described in the detailed description. These and other features, aspects, and advantages will be better understood when the following detailed description is read in conjunction with the accompanying drawings.

[0006] In some glass manufacturing processes, molten glass-forming material is delivered from a delivery system, such as a delivery container, to a downstream process, such as a forming apparatus configured to form the molten material into a glass article. Typically, the molten glass-forming material is delivered through a conduit and discharged from an outlet aperture of the conduit. In various embodiments, the temperature, and therefore the viscosity, of the molten glass-forming material is maintained at an appropriate temperature to facilitate homogeneous transport through the conduit. For example, Figures 1 and 2 show a vertically oriented conduit 10 including an upper electrical flange 12 joined to the conduit 10 and a lower electrical flange 14 joined to the conduit 10 below the upper electrical flange 12 at the discharge end 16 of the conduit from which the molten glass-forming material 18 flows. This can be done by supplying an electric current through the conduit between the upper electrical flange 12 and the lower electrical flange 14, thereby heating the conduit 10 between the upper electrical flange 12 and the lower electrical flange 14 by Joule heating, and as a result, heating the molten glass-forming material 18 in the conduit. Heating the molten glass-forming material using this method is often referred to as "direct" heating, in contrast to indirect methods that use external heat sources such as electric windings placed adjacent to the conduit.

[0007] Electrical flanges are often designed to supply large currents of several hundred to several thousand amperes to conduits. Electrical flanges are not intended to reach high temperatures and are constructed with sufficient thickness to reduce electrical resistance and limit the temperature during operation. In some cases, electrical flanges can be cooled by cooling channels, such as cooling tubes (not shown), arranged around the outer circumference of the electrical flange. Thus, the electrical flange, and in particular the lower electrical flange 14 located at or near the discharge end of the conduit, can function as a heat dissipation fin and cool the discharge end of the conduit. Furthermore, the positioning of the lower electrical flange 14 at the discharge end 16 can reduce Joule heating at the immediate discharge end. If the glass-forming material at the discharge end 16 is cooled to a temperature below the liquidus temperature of the glass-forming material, and the glass-forming material remains at the discharge end for a sufficient amount of time, the glass-forming material can undergo devitrification and form crystalline lumps 22 (hereinafter "debits"). Once the debits 22 are able to grow, they can separate from the conduit and contaminate the downstream glass-forming material. For example, during operation of the glass manufacturing apparatus, molten glass-forming material may move beyond the edge surface 20 of the conduit onto the lower electrical flange 14. This glass-forming material that has moved onto the edge surface and electrical flange 14 can crystallize to form a davit 22, which can then become a seed for further davit growth into the interior of the conduit.

[0008] Accordingly, a glass manufacturing apparatus is disclosed herein, comprising a container configured for feeding molten glass, and a conduit extending downward from the container, wherein the conduit includes a distal end comprising a concave heating member joined thereto, a first electrical flange joined to the conduit, and a second electrical flange joined to the concave heating member. In some embodiments, the concave heating member may include a truncated cone. The concave heating member may be joined perpendicularly to the conduit; that is, the concave heating member may be perpendicular to the conduit at the joint between the concave heating member and the conduit.

[0009] In various embodiments, the concave heating member comprises a small end and a large end, and the second electrical flange is joined to the upper rim of the large end.

[0010] In the embodiment, the second electrical flange may include a body portion having an inner edge that defines an internal opening, the inner edge of which can be joined to the upper rim of the concave heating member with respect to the circumference of the large end.

[0011] In some embodiments, the glass manufacturing apparatus may further include a third electrical flange joined to a conduit between the first electrical flange and the molten glass delivery container.

[0012] The glass manufacturing apparatus may further include a thermally conductive material placed within a defined volume between a concave heating element and the wall of a conduit. The thermally conductive material may include ceramic cement.

[0013] In some embodiments, the thickness of the conduit can be greater than the thickness T2 of the concave heating element.

[0014] In various embodiments, the conduit, the concave heating member, and the second electrical flange may be made of platinum, for example, a platinum-rhodium alloy.

[0015] A glass manufacturing apparatus according to any one of claims 1 to 10, wherein the conduit includes a drain pipe for the container.

[0016] In various embodiments, the concave heating member can be an upward-facing concave heating member.

[0017] In another embodiment, a glass manufacturing apparatus is described, comprising a molten glass delivery container and a conduit extending from the molten glass delivery container, the conduit having a proximal end joined to the molten glass delivery container and a distal end having a conical heating member extending toward the molten glass delivery container from the distal end and an electrical flange joined to the conical heating member.

[0018] The glass manufacturing apparatus may further include ceramic cement placed in a defined volume between a conical heating element and the wall of a conduit.

[0019] In various embodiments, the conduit, the conical heating member, and the second electrical flange may be made of platinum, for example, a platinum-rhodium alloy.

[0020] In some embodiments, the conical heating member may include an arc-shaped neck portion joined orthogonally to its distal end.

[0021] In some embodiments, the thickness T1 of the conduit is greater than the thickness T2 of the conical heating element.

[0022] In yet another embodiment, a glass manufacturing apparatus is disclosed comprising a container configured for feeding molten glass, a conduit extending from the container and in fluid communication with the container, the conduit including a proximal end joined to the container and a distal end opposite to the proximal end and spaced apart from the proximal end, and a concave heating member joined to the conduit, the concave heating member including a large end and a small end and extending around at least a portion of the length of the conduit, and an electric flange joined to the concave heating member at the large end. For example, the small end of the concave heating member can be joined to the conduit.

[0023] In some embodiments, the small end comprises an arc-shaped neck portion having a curved section that curves in the direction of the conduit. For example, the arc-shaped neck portion can be joined perpendicularly to the conduit.

[0024] In some embodiments, the small end of the concave heating element is joined to the distal end of the conduit.

[0025] In some embodiments, the thickness T1 of the conduit is greater than the thickness T2 of the concave heating element.

[0026] In various embodiments, the conduit, concave heating member, and electrical flange include platinum, such as a platinum-rhodium alloy.

[0027] In some embodiments, the concave heating member can be an upward concave heating member.

[0028] In yet other embodiments, a method for preventing devitrification of a molten glass-forming material is disclosed, the method comprising flowing a molten glass-forming material through a conduit, the conduit including a concave heating member joined to the conduit and extending around at least a portion of the length of the conduit, establishing an electric current in the conduit and the concave heating member between a first electrical flange joined to the conduit and a second electrical flange joined to the concave heating member, the concave heating member conductively heating at least a portion of the length of the conduit. The concave heating member includes a large end portion including a first diameter d1 and a small end portion opposite the large end portion. The small end portion can include a second diameter d2 that is smaller than d1.

[0029] In some embodiments, the small end portion can include an arcuate neck portion that curves in a direction toward the conduit and includes a curved portion joined perpendicularly to the conduit.

[0030] In some embodiments, the concave heating member can be joined to the distal end of the conduit.

[0031] In some embodiments, the concave heating member can be an upward concave heating member.

[0032] Additional features and advantages of the embodiments disclosed herein are described in the following detailed description, and in part will be apparent from the description, or will be recognized by those of ordinary skill in the art from the following detailed description, by practicing the embodiments described herein including the claims and the accompanying drawings. It is to be understood that both the foregoing summary and the following detailed description are intended to provide an overview or framework for understanding the nature and characteristics of the embodiments disclosed herein. The accompanying drawings are included to provide further understanding and are incorporated herein and constitute a part of this specification. The drawings illustrate various embodiments of the present disclosure and, together with the description, explain the principles and operations thereof. [Brief explanation of the drawing]

[0033] [Figure 1] This is a schematic diagram of a conduit and a pair of electrical flanges joined to it, for directly heating the molten glass-forming material flowing through the conduit. [Figure 2] Figure 1 is a cross-sectional view of the conduit and electrical flange. [Figure 3] An exemplary glass forming apparatus according to an embodiment disclosed herein, comprising a discharge container and an outlet conduit extending therefrom, wherein an electrical flange is configured to establish an electric current within the outlet conduit. [Figure 4] Figure 1 is a cross-sectional elevation view of the outlet conduit, showing a concave heating element attached to the distal end of the outlet conduit. [Figure 5] This is a perspective view of at least a portion of the outlet conduit in Figure 2, showing the concave heating element. [Figure 6] This is a perspective view of an exemplary first electrical flange. [Figure 7] This is a perspective view of an exemplary second electrical flange. [Figure 8] This is a cross-sectional view of a portion of the concave heating member, showing the distal end of the outlet conduit and the skirt and arc-shaped neck portion that are perpendicularly joined to the outlet conduit. [Figure 9] Figure 4 is a perspective view of at least a portion of the outlet conduit, with first and second electrical flanges attached to the outlet conduit and the upward-facing concave heating member, respectively. [Figure 10] This is a perspective view of another concave heating element having a parabolic shape. [Figure 11] This is a partial cross-sectional view of an exemplary downcomer according to an embodiment described herein, in which the downcomer is shown to deliver molten glass-forming material to an exemplary forming apparatus including a rotational molding roll. [Figure 12] This is a partial cross-sectional view of another exemplary downcomer according to an embodiment described herein, in which the downcomer is shown to deliver molten glass-forming material to a forming apparatus including a pair of counter-rotating forming rolls. [Modes for carrying out the invention]

[0034] Herein, embodiments of the present disclosure, whose examples are illustrated in the accompanying drawings, will be described in detail. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar elements. However, the present disclosure can be embodied in many different forms and should not be construed as being limited to the embodiments described herein.

[0035] As used herein, the term “approximately” means that quantities, sizes, formulations, parameters, and other quantities and characteristics are not, and do not need to be, exact, but are approximate and / or greater or less than, tolerances, conversion factors, rounding, measurement errors, etc., and other factors well known to those skilled in the art, as required.

[0036] In this specification, a range can be expressed as "approximately" from one particular value and / or "approximately" from another particular value. When expressed as such a range, another embodiment includes a range from one particular value to another. Similarly, when a value is expressed as an approximation by the use of the antecedent "approximately," it will be understood that a particular value forms another embodiment. Furthermore, it will be understood that each endpoint of a range is significant in relation to and independently of the other endpoints.

[0037] The directional terms used herein, such as up, down, right, left, front, back, up, and down, are indicated only in reference to the illustrated diagrams and are not intended to mean absolute directions.

[0038] Unless otherwise expressly stated, the methods described herein are not intended to require that the steps be performed in a specific order, nor are they intended to require a specific orientation for any apparatus. Therefore, if a claim for a method does not actually describe the order in which the steps should be followed, or if any apparatus claim does not actually describe the order or orientation for individual components, or if the steps are not otherwise explicitly stated in the claim or specification as being limited to a specific order, or if a specific order or orientation for the components of an apparatus is not described, no order or orientation is intended to be inferred in any way. This applies to all possible non-expressive grounds for interpretation, including logical matters relating to the arrangement of steps, the flow of operation, the order of components, or the orientation of components, general meanings derived from grammatical construction or punctuation, and the number or type of embodiments described herein.

[0039] As used herein, the singular forms "a," "an," and "the" include plural anaphora unless the context clearly indicates otherwise. Thus, for example, a reference to the "a" component includes a configuration having two or more such components unless the context clearly indicates otherwise.

[0040] The terms “exemplary,” “example,” or any of these variations are used herein to mean an example, illustration, or demonstration. No aspect or design described herein as “exemplary” or “example” should be construed as preferable or superior to any other aspect or design. Furthermore, examples are provided solely for clarity and understanding and are not intended to limit or restrict in any way the disclosed subject matter or any relevant portion of this disclosure. Numerous additional or alternative examples of varying scopes could be presented but have been omitted for brevity.

[0041] As used herein, the terms “comprising” and “including,” and their variations thereof, are synonymous and open-ended unless otherwise indicated. The list of elements following the transitional clause “comprising” or “including” is a non-exclusive list in which elements may be added to any elements specifically listed in the list.

[0042] As used herein, the terms “substantial,” “substantially,” and their variations are intended to indicate that the described feature is equal to or approximately equal to a value or description. For example, a “substantially planar” surface is intended to indicate a surface that is planar or substantially planar. Furthermore, “substantially” is intended to indicate that two values ​​are equal to or approximately equal to. In some embodiments, “substantially” can indicate values ​​within about 10% of each other, for example, within about 5% of each other, or within about 2% of each other.

[0043] As used herein, the terms “electrically connected,” “electrically connected,” and variations thereof mean connected via a conductor, such as a metallic conductor, but not including molten materials (e.g., molten glass). A first element electrically connected to a second element may include additional elements between the first and second elements, which are also electrically connected to the first and second elements. That is, a first element electrically connected to a second element is not construed as excluding the presence of additional conductive elements at the connection. Typically, such conductors may include, but are not limited to, metal wiring or cables, busbars, etc. Electrical connections may include, but are not limited to, electrical connectors (e.g., plugs, tabs, lugs, bolts, etc.) that facilitate connection between components, electrical control devices such as current and / or voltage controllers, current and / or voltage measuring devices, etc., and may further include other components.

[0044] In this specification, "refractory material" means a nonmetallic material having chemical and physical properties that make it applicable as a component of a structure or system exposed to an environment exceeding 538°C.

[0045] In this specification, "conical" includes right conical, oblique conical, and truncated conical shapes.

[0046] Unless otherwise specified, the drawings are not to scale.

[0047] Figure 3 shows an exemplary glass manufacturing apparatus 100. In some embodiments, the glass manufacturing apparatus 100 may comprise a glass melting furnace 102 including a melting vessel 104. In addition to the melting vessel 104, the glass melting furnace 102 may optionally include one or more additional components such as heating elements (e.g., a combustion burner and / or electrodes) configured to heat the raw materials and convert the raw materials into molten glass. For example, the melting vessel 104 may be an electrically boosted melting vessel through which energy is added to the raw materials by both a combustion burner and direct heating, in which case an electric current is passed through the raw materials, and the current thereby adds energy through Joule heating of the raw materials.

[0048] In a further embodiment, the glass melting furnace 102 may include other thermal management devices (e.g., isolation components) that reduce heat loss from the melting vessel. In yet another embodiment, the glass melting furnace 102 may include electronic and / or electromechanical devices that facilitate the melting of raw materials into the glass melt. The glass melting furnace 102 may include a support structure (e.g., a support chassis, support members, etc.) or other components.

[0049] The molten vessel 104 can be formed from a refractory material, such as a refractory ceramic material containing alumina and / or zirconia, but the refractory ceramic material may include other refractory materials, such as yttrium (e.g., yttria, yttria-stabilized zirconia, yttrium phosphate), zircon (ZrSiO4), or alumina-zirconia-silica, or other refractory materials such as chromium oxide, which are used alternatively or in any combination. In some embodiments, the molten vessel 104 can be constructed from refractory ceramic bricks.

[0050] In some embodiments, the glass melting furnace 102 can be incorporated as a component of a glass manufacturing apparatus configured to produce glass articles, such as glass ribbons. In further embodiments, the glass manufacturing apparatus may be configured to form other glass articles, such as glass rods, glass tubes, glass envelopes (e.g., glass envelopes for lighting devices, e.g., light bulbs) and glass lenses, for which many other glass articles are intended, but are not limited to these. In some examples, the melting furnace can be included in a glass manufacturing apparatus that includes a slot draw apparatus, a float bath apparatus, a down draw apparatus (e.g., a fusion down draw apparatus), an up draw apparatus, a press apparatus, a rolling apparatus, a tube draw apparatus, or other glass manufacturing apparatus that would benefit from the present disclosure. As an example, Figure 3 schematically shows a glass melting furnace 102 as a component of a fusion down draw glass manufacturing apparatus 100 for fusion drawing glass ribbons for subsequent processing into individual glass sheets or rolling of glass ribbons into spools. As used herein, fusion drawing involves flowing molten glass onto the sides of a formation, the resulting flow of molten material joining or "fusing" at the bottom of the formation.

[0051] The glass manufacturing apparatus 100 may optionally include an upstream glass manufacturing apparatus 106 located upstream of the melting vessel 104. In some examples, part or all of the upstream glass manufacturing apparatus 106 can be incorporated as part of the glass melting furnace 102.

[0052] As shown in the embodiment in Figure 3, the upstream glassmaking apparatus 106 may include a raw material storage bin 108, a raw material delivery device 110, such as an auger or screw feeder, and a motor 120 connected to the raw material delivery device 110. The raw material storage bin 108 may be configured to store a quantity of raw material 122 that can be supplied to the melting vessel 104 via one or more supply ports, as indicated by arrow 124. The raw material 122 typically comprises one or more glass-forming material metal oxides and one or more modifiers. In some embodiments, the raw material delivery device 110 may be powered by the motor 120 to supply a predetermined amount of raw material 122 from the raw material storage bin 108 to the melting vessel 104. In further embodiments, the motor 120 may power the raw material delivery device 110 to introduce the raw material 122 at a controlled rate based on the level of molten material sensed downstream of the melting vessel 104 with respect to the flow direction of the molten material. The raw materials 122 in the molten vessel 104 can then be heated to form a molten glass-forming material 126. Typically, in the initial melting step, the raw materials are added to the molten vessel as particulate matter, for example, various “sands” or powders. The raw materials 122 may also include scrap glass (cullet) from previous melting and / or forming processes. A combustion burner is usually used to initiate the melting process. In an electrically boosted melting process, once the electrical resistance of the raw materials has decreased sufficiently, electric heating can be initiated by generating a potential between electrodes placed in contact with the raw materials, thereby driving an electric current through the raw materials, which typically enters or remains in a molten state. The resulting molten glass-forming material is referred to herein as molten glass 126.

[0053] The glass manufacturing apparatus 100 may optionally include a downstream glass manufacturing apparatus 128 positioned downstream of the glass melting furnace 102 with respect to the flow direction of the molten glass 126. In some embodiments, a portion of the downstream glass manufacturing apparatus 128 can be incorporated as part of the glass melting furnace 102. However, in some embodiments, the first connecting conduit 130, described later, or other portions of the downstream glass manufacturing apparatus 128 can be incorporated as part of the glass melting furnace 102.

[0054] The downstream glassmaking apparatus 128 may include a first conditioning (e.g., processing) chamber, such as a finening vessel 132, located downstream of the molten vessel 104 and coupled to the molten vessel 104 by the first connecting conduit 130. In some examples, molten glass 126 can be gravity-fed from the molten vessel 104 to the finening vessel 132 by the first connecting conduit 130. For example, gravity can drive the molten glass 126 from the molten vessel 104 to the finening vessel 132 through the internal passage of the first connecting conduit 130. Thus, the first connecting conduit 130 provides a flow path for molten glass 126 from the molten vessel 104 to the finening vessel 132. However, it should be understood that other conditioning chambers may be located downstream of the molten vessel 104, for example, between the molten vessel 104 and the finening vessel 132. In some embodiments, the conditioning chamber can be employed between the molten vessel and the finening vessel. For example, the molten glass from the primary melting vessel may be further heated in a secondary conditioning vessel, or it may be cooled in the secondary conditioning vessel to a temperature lower than that of the molten glass in the primary melting vessel before entering the fining chamber.

[0055] Gaseous inclusions can be removed from the molten glass 126 by various techniques. For example, the raw material 122 may contain a polyvalent compound (e.g., a finishing agent) such as tin oxide, which undergoes a chemical reduction reaction and releases oxygen when heated. Other suitable finishing agents include, but are not limited to, arsenic, antimony, iron, and cerium, although the use of arsenic and / or antimony may not be recommended for environmental reasons. The finishing vessel 132 can be heated, for example, to a temperature higher than the molten vessel temperature, thereby heating the finishing agent. Oxygen produced by the temperature-induced chemical reduction of one or more finishing agents contained in the molten glass can rise through the molten glass in the finishing vessel and coalesce or diffuse into bubbles generated during the melting process. The enlarged gas bubbles, with increased buoyancy, then rise to the free surface of the molten glass in the finishing vessel and can then be exhausted from the finishing vessel.

[0056] The downstream glassmaking apparatus 128 may further include another adjustment chamber, such as a mixing apparatus 134, or a stirring vessel, for mixing the molten glass flowing downstream from the finening vessel 132. The mixing apparatus 134 can be used to provide a homogeneous molten glass composition, thereby reducing any chemical or thermal heterogeneity that may exist in the molten glass as it exits the finening chamber. As shown in the figure, the finening vessel 132 can be coupled to the mixing apparatus 134 by a second connecting conduit 136. In some embodiments, the molten glass 126 can be gravity-fed from the finening vessel 132 to the mixing apparatus 134 by the second connecting conduit 136. For example, gravity can drive the molten glass 126 through the internal passage of the second connecting conduit 136 from the finening vessel 132 to the mixing apparatus 134. Typically, the molten glass in the mixing apparatus 134 includes a free surface, with a free volume extending between the free surface and the top of the mixing apparatus. The mixing apparatus 134 is shown downstream of the finening vessel 132 with respect to the flow direction of the molten glass, although in other embodiments, the mixing apparatus 134 may be located upstream of the finening vessel 132. In some embodiments, the downstream glassmaking apparatus 128 may include multiple mixing apparatuses, e.g., mixing apparatuses upstream of the finening vessel 132 and mixing apparatuses downstream of the finening vessel 132. When used, the multiple mixing apparatuses may be of the same design or may be of different designs. In some embodiments, one or more of the vessels and / or conduits may include static mixing vanes placed therein to facilitate the mixing and subsequent homogenization of the molten material.

[0057] The downstream glassmaking apparatus 128 may further include another regulating chamber, such as a delivery vessel 138 located downstream of the mixing apparatus 134. The delivery vessel 138 can regulate the molten glass 126 supplied to the downstream molding device. For example, the delivery vessel 138 may function as an accumulator and / or flow controller to regulate and / or provide a consistent flow of molten glass 126 to the downstream process via an outlet conduit, hereafter downcomer 140. In some embodiments, the molten glass 126 in the delivery vessel 138 may include a free surface, and the free volume extends upward from the free surface to the top of the delivery vessel. As shown, the mixing apparatus 134 may be coupled to the delivery vessel 138 by a third connecting conduit 142. In some examples, the molten glass 126 may be gravity-fed from the mixing apparatus 134 to the delivery vessel 138 via the third connecting conduit 142. For example, gravity can drive the molten glass 126 from the mixing device 134 to the discharge container 138 through the internal passage of the third connecting conduit 142.

[0058] Referring here to Figures 4 and 5, the downcomer 140 comprises a proximal end 144 coupled to and in fluid communication with the delivery vessel 138, and a distal end 146 opposite the proximal end 144 and spaced therefrom along the central longitudinal axis 148 of the downcomer 140. The wall 150 of the downcomer 140 includes an inner surface 154 and an outer surface 156, and the wall 150 defines an internal passage 157 extending between the proximal end 144 and the distal end 146. By gravity, the molten glass 126 can be driven through the internal passage 157 from the delivery vessel 138 to the distal end 146 of the downcomer 140, from where the molten glass can be delivered from the distal end 146 to the forming apparatus 158. For example, the molten glass 126 may be fed into a down-draw glass forming apparatus (e.g., a slot-draw glass forming apparatus, an overflow down-draw), a float-type glass forming apparatus, or a rolled glass forming apparatus, but in further embodiments, the molten glass 126 may be fed into any other glass forming apparatus known in the art.

[0059] As shown in Figure 4, the downcomer 140 is joined to the first electrical flange 160 and electrically connected to the second electrical flange 162 via a concave heating member 164, the first electrical flange 160, and the second electrical flange 162, and is configured to supply current to the downcomer 140. For example, a current can be established in the wall 150 between the first electrical flange 160 and the second electrical flange 162 to heat the wall 150, thereby heating and / or maintaining the temperature of the molten glass flowing through the portion of the downcomer 140 between the first electrical flange 160 and the second electrical flange 162. The first electrical flange 160 is located upstream of the second electrical flange 162, but in a further embodiment, the first electrical flange can be joined to the delivery container 38.

[0060] Referring to Figure 6, the first electrical flange 160 comprises a first body portion 166 and a first electrode portion 168 extending from the first body portion 166. The first body portion 166 includes an inner edge portion 170 that defines an opening 172 that penetrates the first body portion 166.

[0061] Looking at Figure 7, the second electrical flange 162 includes a second body portion 174 and a first electrode portion 176a. In some embodiments, such as the illustrated embodiment, the second electrical flange 162 may include a second electrode portion 176b, and the first electrode portion 176a is positioned on the second body portion 174 opposite the second electrode portion 176b such that the electrode portions 176a and 176b are separated by 180 degrees. The second body portion 174 further includes an inner edge portion 180 that defines an opening 182 through the second body portion 174, and an outer peripheral edge portion 178 relating to the circumference of the body portion. In various embodiments, the first body portion 166 and / or the second body portion 174 may be planar or substantially planar.

[0062] Although not shown, in further embodiments, the first electrical flange may include a second electrode portion opposite to the first electrode portion 168. Similarly, the second electrical flange 162 may consist of a single electrode portion in the same manner as shown for the first electrical flange 160. The use of multiple electrode portions, such as opposing electrode portions, can make the current supplied to the components to which the electrical flanges are joined more uniform around the circumference of the components at the joint.

[0063] In some embodiments, one or more additional electrical flanges can be joined to the downcomer 140 between the first electrical flange 160 and the delivery container 138. For example, Figures 3 and 4 illustrate a third electrical flange 184 attached to the downcomer 140 and positioned above the first electrical flange 160, for example, between the first electrical flange 160 and the delivery container 138. The third electrical flange 184 may be similar to or identical to the first electrical flange 160 according to some embodiments. The third electrical flange 184 may have a single electrode portion or multiple electrode portions. Each electrical flange may be electrically connected to an electrical power source (not shown) and configured to supply current to the electrical flange. The power source may be a local power grid, e.g., a substation, or a separate generator.

[0064] Returning to Figures 4 and 5, in some embodiments, the concave heating member 164 can extend upward from the distal end 146 of the downcomer 140. That is, the concave heating member 164 can be a concave heating member. The concave heating member 164 may include a skirt 186 with a circular cross-section in a plane perpendicular to the longitudinal axis 148, but in further embodiments, the heating member 164 may have a non-circular cross-sectional shape. The upper opening 188 is defined by the upper rim 190 of the concave heating member 164, which has a first diameter d1. The concave heating member 164 further includes a second lower opening 192 defined by a second lower rim 194, which has a second diameter d2 smaller than the first diameter d1. The end of the concave heating member 164 having the largest opening, i.e., the upper opening 188, is defined as the large end 196, while the end of the upward concave heating member 164 having a smaller opening, i.e., the second opening 192, is defined as the small end 198. In some embodiments, the concave heating member 164 can be conical and include, for example, a conical skirt 186. In various embodiments, the small end 198 of the upward concave heating member 164 can include an arcuate neck portion 200 (see Figure 8), where the neck portion 200 includes a curved portion in the direction of the longitudinal axis 148. That is, the arcuate neck portion 200 curves inward toward the downcomer 140 and includes a lower rim 194.

[0065] The inner edge 180 of the second electrical flange 162 is attached to the upper rim 190 of the concave heating member 164, for example by welding, and the lower rim 194 of the concave heating member 164 is attached to or close to the distal end 146 of the downcomer 140. Thus, a cup-shaped volume with a closed bottom is formed between the concave heating member 164 and the wall 150.

[0066] In some embodiments, as best seen in Figure 8 showing region A in Figure 5, the lower rim 194 can be mounted a short distance δ above the distal end 146 to allow sufficient clearance between the weld 195 used to join the lower rim 194 to the wall 150. That is, a welding operation that directly joins the lower rim 194 to the downcomer 140 at the distal end 146 could result in deformation of the distal end 146, which could disrupt the flow of molten glass from the distal end 146. Therefore, the lower rim 194 of the concave heating member 164 can be moved slightly above the distal end 146, for example, δ in the range of about 1 mm to about 3 mm, e.g., about 1 mm to about 1.5 mm, or greater than 0 mm and less than or equal to 1 mm. Thus, as used herein, a reference that the concave heating member is joined to the distal end 146 of the conduit includes a length of the conduit within 3 mm from the distal end. The arc-shaped neck portion 200 can be positioned such that the arc-shaped neck portion is perpendicular to the wall 150 where the lower rim 194 intersects with the wall 150. The perpendicularity of the concave heating member 164 to the downcomer 140 helps maintain a consistent thickness of the concave heating member 164 and avoids potential changes in electrical resistance within the concave heating member 164. In other words, in various embodiments, the wall 150 of the downcomer 140 may have a substantially uniform thickness T1. On the other hand, the concave heating member 164 may have a thickness T2 equal to or less than T1. The current density through a conductor is a function of the magnitude of the current and the cross-sectional area of ​​the conductor. The resistance of the downcomer 140 is proportional to the length of the conductor divided by the cross-sectional area. In other words, the electrical resistance R of the downcomer 140, or a selected portion thereof, is the value obtained by dividing the length L of the downcomer or a selected portion thereof by the cumulative cross-sectional area A in a plane perpendicular to the longitudinal axis 148, assuming a uniform thickness (R∝L / A). The current I of the downcomer 140 is I=E / R, where E is the voltage across the length L and R is the electrical resistance. It will be clear that in each cross-section of the upward concave heating member 164 with respect to a plane perpendicular to the longitudinal axis 148, d1 is greater than d2.In fact, d2 increases as the cross-section of the concave heating member 164 approaches the upper rim 190. If the thickness T2 of the concave heating member 164 is greater than T1, the cross-sectional area A2 of the concave heating member 164 at any given cross-section will be greater than the cross-sectional area A1 of the corresponding cross-section of the downcomer 140. Consequently, the current density in the concave heating member 164 and the thermal power generated by the concave heating member will decrease. Thus, in various embodiments, T2 of the skirt 186 is less than the thickness T1 of the wall 150, where both thicknesses T1 and T2 are measured as the shortest distance between opposing surfaces of the corresponding components (e.g., the distance between opposing surfaces along a line perpendicular to the opposing surfaces, e.g., the perpendicular distance between the inner surface 154 and the outer surface 156 of the downcomer 140). If the concave heating element 164 intersects the downcomer 140 at an angle other than 90 degrees, the cross-sectional area of ​​the concave heating element at the intersection with the downcomer 140 will be different from the cross-sectional area of ​​the concave heating element at other points.

[0067] Figure 9 is a perspective view of a downcomer 140, showing a first electrical flange 160 joined to the downcomer, a concave heating member 164 joined to the distal end of the downcomer, and a second electrical flange 162 joined to the concave heating member 164. In the illustrated embodiment, the concave heating member 164 is arranged as an upward-facing concave heating member, for example, a conical heating member.

[0068] Returning to Figure 4, the thermally conductive material 202 can be placed in the cup-shaped volume 204 between the concave heating member 164 and the wall 150. However, the thermally conductive material 202 should be electrically insulating (non-conductive) to prevent electrical short circuits across the upward concave heating member 164. The thermally conductive material 202 may include castable ceramic cement such as Ceramabond 503, available from Aremco Products (Valley Cottage, NY), EA139, manufactured by Saint-Gobain Abrasives Incorporated, or, for example, a mixture of Ceramabond and EA139.

[0069] The thermally conductive material 202 functions to conduct heat generated by the current in the concave heating member 164 (between the first electrical flange 160 and the second electrical flange 162) to that portion of the downcomer 140 in contact with the thermally conductive material 202. Furthermore, since the thickness T2 of the concave heating member 164 can be made thin, the thermally conductive material 202 can provide structural rigidity to the concave heating member, thereby preventing distortion or collapse of the upward-facing concave heating member. The size of the concave heating member 164 (e.g., height, diameter, thickness) and the magnitude of the current supplied between the first electrical flange 160 and the second electrical flange 162 are selected to supply sufficient thermal energy to the distal end 146 so that the molten glass moving to the end face of the distal end 146 or the outer surface of the concave heating member 164 is maintained at a temperature above the liquidus temperature of the molten glass. Therefore, the distal end 146 can be heated by conduction from the concave heating member 164 and directly by the wall 150 through Joule heating of the wall.

[0070] According to various embodiments, the first thermal insulation material 206 can be placed between the first electrical flange 160 and the second electrical flange 162, for example, between the first body portion 166 and the second body portion 174. The first thermal insulation material can be a ceramic fiber board (e.g., aluminosilica and / or mullite fiber and binder), such as Unifrax Fiberfrax® Duraboard® 3000, or ZIRCAR RS-100 refractory sheet manufactured by ZIRCAR Refractory Composites, Incorporated. In some embodiments, the second thermal insulation material 207 can also be placed between the first electrical flange 160 and the second electrical flange 162. The second thermal insulation material 207 can be a refractory brick suitable for supporting the weight of insulating material or other material placed above the first electrical flange 160. The second thermal insulation material 207 may include alumina and / or zirconia, but other refractory brick materials known in the art may also be used.

[0071] In some embodiments, the third thermal insulation material 208 is positioned below the second electrical flange 162 and can be in contact with the second electrical flange 162. The third insulation material 208 can be the same material as the first insulation material 206, for example, a ceramic fiber board such as Unifrax Fiberfrax® Duraboard® 3000 and / or ZIRCAR RS-100 refractory sheet. The third insulation material 208 can define a passage 210 of sufficient diameter to allow a stream of molten glass discharged from the distal end 146 of the downcomer 140 to pass through the second insulation material 208 without contacting the insulation material 208.

[0072] A fourth insulating material 212, such as a castable refractory material, can surround the downcomer 140. Furthermore, in some embodiments, a fifth insulating material 214, such as a refractory refractory brick, can surround the fourth insulating material 212. The fifth insulating material 214 may include, for example, alumina and / or zirconia, but other refractory materials may also be used.

[0073] Components of the downstream glassmaking apparatus 128, including connecting conduits 130, 136, 142, finening vessel 132, mixing apparatus 134, delivery vessel 138, downcomer 140, or electrical flanges 160, 162, or 184, can be formed from precious metals. Suitable precious metals include platinum group metals selected from the group including platinum, iridium, rhodium, osmium, ruthenium, and palladium, or alloys thereof. For example, the downstream components of the glassmaking apparatus may be formed from or include a platinum-rhodium alloy containing about 70% to about 90% by weight of platinum and about 10% to about 30% by weight of rhodium. However, other metals suitable for forming the downstream components of the glassmaking apparatus include molybdenum, rhenium, tantalum, titanium, tungsten, and alloys thereof.

[0074] The downcomer 140, the fourth insulation material 212, and the fifth insulation material 214 can be supported by one or more steel structural elements 216 arranged around the fifth insulation material 214.

[0075] In a further embodiment, the concave heating member 164 may have a parabolic shape as shown in Figure 10, resulting in a bowl-shaped volume positioned between the concave heating member 164 and the outer surface 156 of the downcomer wall 150. However, the concave heating member 164 may have other concave shapes, such as a hemisphere.

[0076] Figure 3 further shows exemplary embodiments of a forming apparatus 158, which includes one or more forming rolls 218 arranged to produce a glass ribbon 220. For example, in some embodiments, as shown in Figure 11, the forming apparatus may include a single forming roll 218 arranged to rotate around a pivot axis, and molten glass 126 is fed to the top of the forming roll 218 by a downcomer 140. The molten glass rotates with the forming roll and is ejected near the bottom of the forming roll 218 as a glass ribbon 220. In another embodiment shown in Figure 12, the molten glass is fed by the downcomer 140 between a first rotational forming roll 218a and a second counter-rotational forming roll 218b positioned spaced apart from the first rotational forming roll 218a. The molten glass is pressed between the two counter-rotational forming rolls and emerges from between the two counter-rotational forming rolls as a glass ribbon 220.

[0077] The concave heating member does not need to be used in combination with a conduit intended to deliver molten glass to a forming apparatus. For example, various containers (or conduits) within a glass manufacturing apparatus may require drainage at some point in their operation. These containers may be provided with drain tubes, and these drain tubes may be fitted with the concave heating member described herein, used in conjunction with an electrical flange attached thereto, as described above with respect to the downcomer. Furthermore, in some embodiments, a concave heating member similar to the concave heating member described herein may be used at any position on a conduit where additional thermal energy is required, and therefore may not be limited to being concave upward (e.g., joined to a vertically positioned conduit or tube), but may be oriented in other directions. Furthermore, the concave heating member may not be limited to the end of a tube or conduit, but may be positioned to surround a portion of the intermediate part of a tube or conduit.

[0078] While various embodiments have been described in detail in relation to their specific exemplary and concrete examples, this disclosure should not be considered limiting, as numerous modifications and combinations of the disclosed features are possible without departing from the following claims. [Explanation of symbols]

[0079] 140 Downcomer 160 First Electric Flange 162 Second Electric Flange 164 Concave heating element

Claims

1. A glass manufacturing apparatus, A container configured to transport molten glass, A conduit extending downward from the container, having a distal end that includes a concave heating member joined thereto, A first electrical flange joined to the conduit, A second electrical flange joined to the aforementioned concave heating member, The system comprises a heat-conductive material disposed within a defined volume between the concave heating member and the wall of the conduit, The concave heating member includes a large end having a first diameter and a small end having a second diameter smaller than the first diameter. The small end is connected to the distal end of the conduit, and the concave heating member surrounds the distal end. Glass manufacturing equipment.

2. The concave heating member includes a truncated cone, The glass manufacturing apparatus according to claim 1.

3. The second electrical flange is joined to the upper rim of the large end, The glass manufacturing apparatus according to claim 1 or 2.

4. The second electrical flange includes a main body portion having an inner edge that defines an internal opening, the inner edge being joined to the upper rim of the concave heating member around the outer circumference of the large end. The glass manufacturing apparatus according to claim 3.

5. The device further comprises a third electrical flange electrically connected to the conduit between the first electrical flange and the container for transporting the molten glass, A glass manufacturing apparatus according to any one of claims 1 to 4.

6. The thermal conductive material includes ceramic cement, The glass manufacturing apparatus according to claim 1.

7. The thickness of the conduit is greater than the thickness T2 of the concave heating member. A glass manufacturing apparatus according to any one of claims 1 to 6.

8. A method for preventing devitrification of a molten glass forming material, A step of flowing the molten glass-forming material into a conduit, wherein the conduit includes a concave heating member joined to the conduit and extending around at least a portion of the length of the conduit, the concave heating member includes a large end having a first diameter d1 and a small end opposite the large end, the small end having a second diameter d2 smaller than d1, the small end being connected to the distal end of the conduit, the concave heating member surrounding the distal end, and the heat-conductive material being disposed within a defined volume between the concave heating member and the wall of the conduit, The steps include establishing an electric current between the conduit and the concave heating member between a first electric flange joined to the conduit and a second electric flange joined to the concave heating member, thereby conducting heat to at least a portion of the length of the conduit by the concave heating member, Methods that include...

9. The small end includes a curved portion that curves toward the conduit and an arc-shaped neck portion that is joined perpendicularly to the conduit. The method according to claim 8.

10. The aforementioned concave heating member is an upward-facing concave heating member. The method according to claim 8 or 9.

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