Apparatus for forming molten glass using a structurally reinforced conduit - Patent application

Abstract

A glass manufacturing apparatus including a conduit defining an internal passage for conveying molten glass, the conduit including at least one reinforcing member disposed about and attached to at least a portion of an outer circumferential surface of the conduit.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority under 35 U.S.C. Section 119 of U.S. Provisional Patent Application Serial No. 63 / 257,778, filed October 20, 2021, the contents of which are reliably incorporated herein by reference in their entirety.

[0002] SUMMARY The present disclosure relates to apparatus for forming molten glass, and more particularly to a conduit for transporting molten glass that includes a reinforcing member to prevent collapse of the conduit. [Background technology]

[0003] Typically, a manufacturing apparatus for forming molten glass includes a conduit configured to transport the molten glass from one station of the apparatus to another. For example, the conduit may extend between a melting vessel and a downstream component, such as a stirring vessel. Because molten glass is hot and corrosive, many components of the manufacturing apparatus are formed from heat- and corrosion-resistant metals, often selected from platinum group metals. These metals are expensive, and therefore often thin-walled. For some glasses, the processing temperature may be close to the melting temperature of the metal. Because the metal is very thin, the component structures lack significant strength and tend to collapse over time. Summary of the Invention

[0004] In a first aspect, a glass forming apparatus is disclosed that includes a conduit including a metal conduit wall defining an internal passage and configured to convey a flow of molten glass through the internal passage, and at least one reinforcing member extending around at least a portion of an outer periphery of the conduit and attached to the metal conduit wall, the reinforcing member being disposed between and spaced apart from a pair of adjacent electrical flanges.

[0005] In a second embodiment, the at least one reinforcing member of the first embodiment can span at least an upper portion of the metal conduit wall.

[0006] In a third aspect, at least one reinforcing member of the first or second aspect may extend circumferentially around the conduit.

[0007] In a fourth aspect, the at least one reinforcing member of any of the first to third aspects may include a plurality of reinforcing members.

[0008] In a fifth aspect, at least one reinforcing member of any of the first to fourth aspects may include a hollow interior.

[0009] In a sixth aspect, at least one reinforcing member of any of the first to fifth aspects may include a pressure equalizing orifice that provides fluid communication between the hollow interior and an atmosphere outside the hollow interior of the reinforcing member.

[0010] In a seventh embodiment, the metallic conduit wall of any of the first to sixth embodiments may comprise platinum.

[0011] In an eighth aspect, at least one reinforcing member of any of the first through seventh aspects may comprise platinum.

[0012] In a ninth aspect, the glass forming apparatus of any of the first through eighth aspects can be a fining vessel.

[0013] In a tenth aspect, at least one reinforcing member of any of the first to ninth aspects may be attached to the conduit by a plate.

[0014] In an eleventh aspect, the at least one reinforcing member of the tenth aspect can be spaced from the conduit by a gap.

[0015] In a twelfth aspect, the cross-sectional shape of at least one reinforcing member of any one of the first to eleventh aspects can be rectangular or circular.

[0016] In a thirteenth aspect, a glass forming apparatus is described that includes a fining vessel including a metal wall defining an internal passage and configured to convey a flow of molten glass through the internal passage, and at least one reinforcing member extending around at least a portion of an outer periphery of the fining vessel, attached to the metal wall, and positioned between and spaced from a pair of adjacent electrical flanges.

[0017] In a fourteenth aspect, at least one reinforcing member of the thirteenth aspect can extend circumferentially around the fining vessel.

[0018] In a fifteenth embodiment, the metal wall of the fourteenth embodiment or the fifteenth embodiment can comprise platinum.

[0019] In a sixteenth aspect, at least one reinforcing member of any of the thirteenth to fifteenth aspects can comprise platinum.

[0020] In a seventeenth aspect, at least one reinforcing member of any of the thirteenth to sixteenth aspects may comprise a hollow interior.

[0021] Both the foregoing general description and the following detailed description present embodiments that are intended to provide an overview or framework for understanding the nature and character of the embodiments. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. These drawings illustrate various embodiments of the present disclosure, and together with the description explain the principles and operation of the various embodiments. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of an exemplary glass manufacturing apparatus. [Diagram 2]FIG. 1 shows cross-sectional views of a conduit carrying molten glass (a) when first placed into service, (b) after the top of the conduit has collapsed after a period of operation at high temperature, and (c) after the collapse has become sufficient that the collapsed top of the conduit contacts the free surface of the molten glass therein, effectively isolating the void at one end of the conduit from the void at the other end of the conduit. [Diagram 3] FIG. 2(b) is a longitudinal cross-sectional view of the conduit of FIG. 2(a). [Figure 4] FIG. 1 is a cross-sectional view of an exemplary conduit, such as a fining vessel, showing a reinforcing member attached to the periphery. [Diagram 5] FIG. 1 is a perspective view of an exemplary conduit showing reinforcing members disposed about its periphery. [Figure 6] FIG. 13 is a perspective view of another exemplary conduit showing a reinforcing member partially disposed therearound. [Figure 7] 1 is a cross-sectional view of an exemplary conduit showing a reinforcing member disposed partially about its periphery and the angle α that the reinforcing member subtends with respect to top dead center (TDC). [Figure 8] Various cross-sectional views of exemplary hollow reinforcing members attached to a conduit wall, including (a) a channel, (b) a box-shaped, (c) a cylindrical tube attached with a plate with no gap between it and the conduit wall, (d) a cylindrical tube attached with a plate with a gap between it and the conduit wall, and (e) a cylindrical tube attached without a plate. [Figure 9] 1A-1C are various cross-sectional views of exemplary solid reinforcing members attached to a conduit wall, including (a) a square member, (b) a cylindrical bar attached with a plate with no gap between it and the conduit wall, (c) a cylindrical bar attached with a plate with a gap between it and the conduit wall, (d) a cylindrical bar attached without a plate, (e) a "T" shaped reinforcing member, and (f) an "I" shaped reinforcing member. [Figure 10] FIG. 1 is a perspective view of a portion of a conduit showing a reinforcing member that includes a pressure equalizing orifice and mates with a crimp in the wall of the conduit. [Figure 11] FIG. 2 is a cross-sectional elevation view of an exemplary conduit (eg, fining vessel) surrounded by a refractory support material. [Figure 12A]FIG. 1 is a perspective view of a modeled temperature distribution in an exemplary conduit (e.g., a fining vessel) directly heated by an electrical flange without a stiffening member. [Figure 12B] FIG. 12B is a perspective view of a modeled temperature distribution in the exemplary conduit (e.g., fining vessel) of FIG. 12A with a stiffening member and directly heated by an electrical flange. [Figure 13A] FIG. 1 is a perspective view of a modeled current density distribution in an exemplary conduit (e.g., a fining vessel) directly heated by an electrical flange without a stiffening member. [Figure 13B] FIG. 13B is a perspective view of a modeled current density distribution in the exemplary conduit (e.g., fining vessel) of FIG. 13A with a reinforcing member and directly heated by an electrical flange. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0024] As used herein, the term "about" means that quantities, sizes, compositions, parameters, and other quantities and characteristics are not, or need not be, exact, but are approximate and / or larger or smaller, as appropriate, to reflect tolerances, conversion factors, rounding, and measurement errors, as well as other factors well known to those of ordinary skill in the art.

[0025] Ranges may be expressed herein as from "about" one particular value, and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value to the other particular value. Similarly, when values ​​are expressed as approximations, by the use of the antecedent "about," it will be understood that the values ​​form another embodiment. It will be further understood that the endpoints of each range may be significant in relation to the other endpoint, or independently of the other endpoint.

[0026] As used herein, directional terms such as up, down, right, left, front, back, top, bottom, etc. are used merely with reference to the figures and do not imply absolute orientation.

[0027] Unless expressly stated otherwise, any method set forth herein should never be construed as requiring that its steps be performed in a particular order, and any apparatus should never be construed as requiring a particular orientation. Thus, unless a method claim actually recites an order that its steps are to be followed, or an apparatus claim actually recites an order or orientation for individual components, or unless the claim or this specification specifically indicates that the steps are to be limited to a particular order, or recites a particular order or orientation for the apparatus components, no order or orientation is to be implied in any way. This applies on all possible non-express basis for interpretation, including logical considerations regarding sequence of steps, operational flow, component order or component orientation, general meaning derived from grammatical construction or punctuation, and the number or type of embodiments described herein.

[0028] As used herein, the singular indefinite articles "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, the phrase "a component" includes aspects having two or more such components, unless the context clearly dictates otherwise.

[0029] As used herein, "exemplary," "example," or various forms thereof, means serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" or "example" is not to be construed as preferred or advantageous over other aspects or designs. Moreover, examples are merely presented for clarity and understanding and are not meant to limit or constrain in any way the disclosed subject matter or relevant portions of this disclosure. It can be understood that numerous additional or alternative examples of various scopes could have been presented but have been omitted for the sake of brevity.

[0030] As used herein, the terms "comprising" and "including" and variations thereof should be construed as synonymous and inclusive unless otherwise indicated. The list of elements following the transition phrase "comprising" or "including" is a non-exclusive list, and therefore there may be other elements present than those specifically listed in the list.

[0031] As used herein, the terms "substantial," "substantially," and variations thereof, are intended to describe a described feature being equal or nearly equal to a value or description. For example, a "substantially planar" surface is intended to describe a surface that is planar or nearly planar. Additionally, "substantially" is intended to describe two values ​​being equal or nearly equal. In some embodiments, "substantially" can describe values ​​within about 10% of each other, such as within about 5% of each other or within about 2% of each other.

[0032] As used herein, the term conduit generally refers to a structure defining a hollow interior configured to transport molten glass. A conduit may be configured for that purpose or to perform additional functions. For example, a structure configured to remove gases from molten glass is referred to herein as a fining vessel, yet such a structure is still generally included in the family of conduits.

[0033] An exemplary glass manufacturing apparatus 10 is shown in FIG. The glass manufacturing apparatus 10 includes a glass melting furnace 12 that includes a melting vessel 14. In addition to the melting vessel 14, the glass melting furnace 12 can optionally include one or more additional components, such as heating elements (e.g., combustion burners and / or electrodes) configured to heat the raw material and convert the raw material into a molten material, hereinafter referred to as molten glass. For example, the melting vessel 14 can be an electrically-boosted melting vessel in which energy is added to the raw material by both combustion burners and direct heating, where the current adds energy by passing an electric current through the raw material via Joule heating of the raw material.

[0034] The glass melting furnace 12 may include other thermal management devices (e.g., thermal insulation components) to reduce heat loss from the melting vessel. The glass melting furnace 12 may include electronic and / or electromechanical devices to facilitate melting of the raw materials into a glass melt. The glass melting furnace 12 may also include a support structure (e.g., a support chassis, support members, etc.) or other components.

[0035] The melting vessel 14 may be formed from a refractory material, such as a refractory ceramic material including, for example, alumina or zirconia, but may also include other refractory materials, such as yttrium (e.g., yttria, yttria stabilized zirconia, yttrium phosphate), zircon (ZrSiO4) or alumina-zirconia-silica, or chromium oxide, used alternatively or in any combination. In some examples, the melting vessel 14 may be constructed from refractory ceramic bricks.

[0036] The glass melting furnace 12 can be incorporated as a component of a glass manufacturing apparatus configured to produce glass articles such as, for example, glass ribbons, but the glass manufacturing apparatus can also be configured to form other glass articles such as, without limitation, glass rods, glass tubes, glass envelopes (e.g., glass envelopes for lighting devices such as light bulbs), and glass lenses. In some examples, the melting furnace 12 can be included in a glass manufacturing apparatus including a slot draw apparatus, a float bath apparatus, a downdraw apparatus (e.g., a fusion downdraw apparatus), an updraw apparatus, a pressing apparatus, a rolling apparatus, a tube drawing apparatus, or any other glass manufacturing apparatus that would benefit from the present disclosure. As an example, FIG. 1 shows a schematic of the glass melting furnace 12 as a component of a fusion downdraw glass manufacturing apparatus 10 that fusion draws a glass ribbon for subsequent processing into individual glass sheets or winding the glass ribbon onto a spool. As used herein, the fusion draw process involves flowing molten glass over sloping, e.g., converging, sides of a forming body such that the resulting streams of molten material meet or "fuse" at the bottom of the forming body to form a ribbon.

[0037] Optionally, the glass manufacturing system 10 may include an upstream glass manufacturing apparatus 16 disposed upstream of the melting vessel 14. In some examples, part or all of the upstream glass manufacturing apparatus 16 may be incorporated as part of the glassmelting furnace 12.

[0038] As shown in FIG. 1, the upstream glass manufacturing apparatus 16 can include a raw material storage bin 18, a raw material delivery device 20, and a motor 22 connected to the raw material delivery device 20. The raw material storage bin 18 can be configured to store raw material 24 that can be fed to the melting vessel 14 of the glass melting furnace 12 through one or more feed ports as indicated by arrow 26. Typically, the raw material 24 includes one or more glass-forming metal oxides and one or more modifiers. In some examples, the raw material delivery device 20 can be driven by the motor 22 to deliver a predetermined amount of raw material 24 from the raw material storage bin 18 to the melting vessel 14. In a further example, the motor 22 can drive the raw material delivery device 20 to introduce the raw material 24 at a controlled rate based on a level of molten glass sensed downstream from the melting vessel 14 relative to the flow direction of the molten glass. The raw material 24 in the melting vessel 14 can then be heated to form molten glass 28. Typically, the raw material is added to the melting vessel as a particulate material, such as various "sands." The feedstock 24 may also include waste glass (i.e., cullet) from previous melting and / or forming operations. A combustion burner may be used to initiate the melting process. In an electrically boosted melting process, once the electrical resistance of the feedstock has been sufficiently lowered by the combustion burner, an electrical boost may be initiated by generating an electrical potential between electrodes placed in contact with the feedstock, which typically results in an electrical current being established through the feedstock as it enters or is in a molten state.

[0039] The glass manufacturing system 10 may also include a downstream glass manufacturing system 30 disposed downstream of the glassmelting furnace 12 relative to the flow direction of the molten glass 28. In some examples, a portion of the downstream glass manufacturing system 30 may be incorporated as part of the glassmelting furnace 12. For example, a first connecting conduit 32, described below, or other portions of the downstream glass manufacturing system 30 may be incorporated as part of the glassmelting furnace 12.

[0040] The downstream glass production apparatus 30 may include a first conditioning chamber, such as a fining vessel 34, disposed downstream of the melting vessel 14 and coupled to the melting vessel 14 by a first connecting conduit 32 as described above. In some examples, the molten glass 28 may be gravity fed from the melting vessel 14 to the fining vessel 34 via an internal passage of the first connecting conduit 32. Thus, the first connecting conduit 32 provides a flow path for the molten glass 28 from the melting vessel 14 to the fining vessel 34. However, other conditioning chambers may also be disposed downstream of the melting vessel 14, such as between the melting vessel 14 and the fining vessel 34. In some embodiments, a conditioning chamber may be employed between the melting vessel and the fining chamber. For example, the molten glass from the primary melting vessel may be further heated in a secondary melting (conditioning) vessel or cooled in the secondary melting vessel to a temperature lower than the temperature of the molten glass in the primary melting vessel before entering the fining chamber.

[0041] Bubbles may be removed from the molten glass 28 by a variety of techniques. For example, the raw material 24 may include multivalent compounds (i.e., fining agents), such as tin oxide, that undergo a chemical reduction reaction when heated to release oxygen. Other suitable fining agents may include, but are not limited to, arsenic, antimony, iron, and / or cerium, although arsenic and antimony are toxic and may not be recommended for some applications for environmental reasons. The fining vessel 34 may be heated, for example, to a temperature higher than the internal temperature of the melting vessel, thereby heating the fining agents. Oxygen produced by the temperature-induced chemical reduction of one or more fining agents in the molten glass may coalesce or diffuse into the gas bubbles created during the melting process. This causes the enlarged and more buoyant gas bubbles to rise to the free surface of the molten glass in the fining vessel, where they may then be evacuated from the fining vessel, for example, through a vent tube in fluid communication with the atmosphere above the free surface.

[0042] The downstream glass production apparatus 30 may further include another conditioning chamber, such as a mixing device 36, e.g., a stirring vessel, for mixing the molten glass flowing downstream from the fining vessel 34. The mixing device 36 may be used to provide a homogenous glass melt composition, thereby reducing chemical and / or thermal inhomogeneities that may be present in the molten glass exiting the fining vessel. As shown, the fining vessel 34 may be coupled to the mixing device 36 via a second connecting conduit 38. Thus, the molten glass 28 may be gravity fed from the fining vessel 34 to the mixing device 36 through an internal passage of the second connecting conduit 38. For example, gravity may drive the molten glass 28 from the fining vessel 34 to the mixing device 36. Typically, the molten glass in the mixing device 36 includes a free surface, with a free (e.g., gas) volume extending between the free surface and the top of the mixing device. Although the mixing device 36 is shown downstream of the fining vessel 34 with respect to the flow direction of the molten glass 28, in other embodiments, the mixing device 36 may be located upstream of the fining vessel 34. In some embodiments, the downstream glass manufacturing equipment 30 can include multiple mixing devices, such as a mixing device upstream from the fining vessel 34 and a mixing device downstream from the fining vessel 34. When multiple mixing devices are used, they can be of the same design or of different designs. One or more of the vessels and / or conduits can include static mixing vanes positioned therein to promote mixing and subsequent homogenization of the molten materials.

[0043] The downstream glass manufacturing apparatus 30 may further include another conditioning chamber, such as a delivery vessel 40 disposed downstream of the mixing device 36. The delivery vessel 40 may function as an accumulator and / or flow controller to regulate and / or provide a consistent flow of the molten glass 28 through an outlet conduit 44 to the forming body 42. In some embodiments, the molten glass in the delivery vessel 40 may include a free surface from which a free volume extends upwardly to the top of the delivery vessel. As shown, the mixing device 36 may be coupled to the delivery vessel 40 through a third connecting conduit 46. In some examples, the molten glass 28 may be gravity fed from the mixing device 36 to the delivery vessel 40 through an internal passage of the third connecting conduit 46.

[0044] The downstream glass manufacturing system 30 may further include a forming apparatus 48 including the forming body 42 described above, which includes an inlet conduit 50. The outlet conduit 44 may be positioned to deliver the molten glass 28 from the delivery vessel 40 to the inlet conduit 50 of the forming apparatus 48. The forming body 42 in a fusion downdraw glass manufacturing system may include a trough 52 disposed within an upper surface of the forming body, and opposing converging forming surfaces 54 that converge in a draw direction 56 along a lower end (root) 58 of the forming body. Molten glass delivered to the forming body trough 52 via the delivery vessel 40, the outlet conduit 44, and the inlet conduit 50 overflows the walls of the trough 52 and descends along the converging forming surfaces 54 as separate streams of molten glass. The separate streams of molten glass merge below and along the root 58 to produce a single ribbon 60 of molten glass that is drawn from the root 58 in a drawing direction 56 by applying a downward tension to the glass ribbon, such as by gravity and / or counter-rotating opposing drawing rolls (see FIG. 2). As the molten material cools and the viscosity of the material increases, the downward tension and the temperature of the molten material can be used to control the dimensions of the ribbon (hereafter glass ribbon). Thus, the glass ribbon 60 undergoes a viscous transition from a viscous state through a viscoelastic state to an elastic state, acquiring mechanical properties that give the glass ribbon 60 stable dimensional properties. The glass ribbon 60 can be separated into short lengths, such as glass sheets 62, by a glass separator 64. Alternatively, the glass ribbon can be spooled.

[0045] The components of the downstream glass manufacturing equipment 30, including any one or more of the connecting conduits 32, 38, 46, the fining vessel 34, the mixing device 36, the delivery vessel 40, the outlet conduit 44, or the inlet conduit 50, may be formed from a precious metal. Suitable precious metals include platinum group metals selected from the group consisting of platinum, iridium, rhodium, osmium, ruthenium, and palladium, or alloys thereof. For example, the downstream components of the glass manufacturing equipment may be formed from a platinum-rhodium alloy including about 70% to about 90% platinum and about 10% to about 30% rhodium by weight.

[0046] For certain components of the glass manufacturing equipment, particularly those metal components operating at high temperatures above about 1300°C, such as above about 1400°C, above about 1500°C, above about 1600°C, or above about 1700°C, but below the melting point of the metal component, the high temperatures to which they are subjected and the thinness of the components can compromise the structural integrity of the components. That is, platinum and other platinum group metals (and / or alloys thereof) are expensive. Thus, components incorporating these metals (including, for example, any one or more of the connecting conduits 32, 38, 46, the fining vessel 34, the mixing device 36, the delivery vessel 40, the outlet conduit 44, or the inlet conduit 50) are thin-walled to control costs, e.g., having a thickness of about 0.254 cm or less. For example, the melting point of pure platinum is 1768°C. Some optical quality glass manufacturing equipment, such as for aluminosilicate glasses such as glass substrates used in the manufacture of optical display devices, has platinum-containing components that operate at temperatures above 1600°C, or even above 1700°C, which is very close to the melting point of platinum. One such example is the fining vessel, a specialized metal conduit used to remove gases (e.g., gas bubbles) from the molten glass. The fining vessel operates in a partially unfilled state; that is, a gaseous atmosphere is maintained above the free surface of the molten glass, providing an area within the fining vessel where gases removed from the molten glass can accumulate and emanate from the fining vessel. However, at least this gaseous atmosphere is less efficient at removing heat from the fining vessel than the molten glass adjacent the lower portion of the fining vessel, so the upper portion of the fining vessel may be hotter than the lower portion. Also, the gaseous atmosphere provides less mechanical and / or hydraulic support than a comparable conduit completely filled with molten glass. Over time, the upper portion of the fining vessel may sink downwards due to gravity, narrowing the internal passageway of the fining vessel. This collapse increases the resistance to the flow of molten glass through the fining vessel and can potentially lead to structural failure of the fining vessel (e.g., breakage of the fining vessel). Other vessels, such as the connecting conduits described herein, may also suffer such consequences for these or other reasons.

[0047] As an example, Figure 2 shows multiple cross-sectional views (in planes perpendicular to the longitudinal axis) of an exemplary fining vessel 34 at multiple times, e.g., (a) at the beginning of the melting operation, and (b) and (c) after extended periods of operation, e.g., after 10,000 hours of operation. Figure 3 shows a longitudinal cross-sectional view of the fining vessel of Figure 2. View (a) of Figure 2 shows the exemplary fining vessel 34 including a wall 70 that defines an initial circular cross-sectional shape. However, the fining vessel can have other initial cross-sectional shapes, such as an elliptical, oval, or another curvilinear shape. In the illustration, view (b) of Figure 2 shows a downward displacement 80 of the top of the fining vessel after extended periods of operation (e.g., 10,000 hours) at molten glass processing temperatures. In some cases, the downward displacement may be great enough that the collapsed top of the fining vessel contacts the molten glass being conveyed therein, as shown in view (c) of Figure 2. In the view of FIG. 3, the ends of the fining vessel are supported by electrical flanges 82 located and attached to those ends to prevent collapse of the fining vessel 34 at the supported ends, with the greatest displacement occurring at or near the unsupported center of the fining vessel, furthest from the electrical flanges. Autopsies performed on removed fining vessels have shown that the top can collapse in the range of about 18 millimeters (mm) to over 24 mm over extended high temperature operation. As suggested by view (c) of FIG. 2, if the collapse of the top of the fining vessel is large enough, the top of the fining vessel may come into contact with the molten glass in the fining vessel. Proper operation of the fining vessel relies on maintaining a molten glass-free volume in the fining vessel above the free surface of the molten glass which forms a reservoir where gas removed from the molten glass can accumulate and escape from the fining vessel. Venting relies on free gas communication throughout the entire molten glass-free volume at the top of the finer, such as between two electrical flanges. For example, if the vent is located at one end of the finer and finer collapse causes the top wall of the finer to contact the molten glass, this contact may isolate one portion of the molten glass-free volume from another portion of the molten glass-free volume, thus preventing free gas flow through the molten glass-free volume and potentially preventing venting of accumulated gas.That is, if a portion of the finer top wall collapses and contacts the molten glass, isolated pockets of gas can form within the finer that are blocked from the finer vents and therefore cannot escape from the finer. Such trapped gas can remelt into the molten glass or cause pressure buildup within the finer, potentially resulting in vessel failure.

[0048] Previous attempts to support the top of molten glass carrying conduits include metal tabs welded to the outside of the conduit and secured to the supporting refractory material. However, these attempts have not prevented collapse because the placement of the tabs may not prevent collapse between the tabs. Furthermore, these tabs make it difficult, if not impossible, for the conduit to move within the surrounding refractory due to thermal expansion and contraction, leading to stress fracture of the conduit, and loss of refractory material due to leakage of molten glass may cause the tabs to fail to function as secured thereto. To inhibit collapse and extend the life of molten glass carrying metal components, these components can be strengthened by adding reinforcing members as described below in this specification.

[0049] 4, a cross-sectional side view of an exemplary fining vessel 134 that can be used in place of the fining vessel 34 in the apparatus of FIG. 1 is shown. The fining vessel 134 includes a wall 136 that defines an interior passageway 138 therethrough between an inlet 140 and an outlet 142 thereof. The cross-sectional shape of the fining vessel 134 can be circular, elliptical, oval, or any combination of curved and optionally planar shapes. The inlet 140 of the fining vessel 134 is directly or indirectly coupled to the first connecting conduit 32, and the outlet 142 is directly or indirectly coupled to the second connecting conduit 38. The fining vessel wall 136 has a plurality of electrical flanges 82 attached thereto, such as by welding, around its periphery. The electrical flanges are metal structures in electrical communication with a current source (not shown) such that a current can be established through the fining vessel wall 136 between the electrical flanges 82. The power source can be an alternating current (AC) source. Typically, the electrical flanges include one or more metal rings attached to the outer surface of the conduit (e.g., fining vessel) wall. In the case of multiple rings, the rings may form concentric rings around the conduit. The concentric rings may be coplanar. The rings may be of different thicknesses. The inner ring, e.g., the innermost ring, may be made of the same material as the conduit, e.g., platinum or a platinum-rhodium alloy comprising about 70% to about 90% platinum and about 10% to about 30% rhodium by weight. The inner ring may be thinner than the outer ring. The outermost ring, which is located further from the high temperature of the conduit than the inner ring, may be made of a low-refractory metal, e.g., nickel. Thus, the fining vessel 134 may be directly heated by resistive (Joule) heating of the fining vessel wall. Additional electrical flanges 82 may also be attached to other conduits, e.g., the first and second connecting conduits 32 and 38, as well as the fining vessel 34.

[0050] Electrical flanges 82 can be used to divide the fining vessel 134 or any other conduit into temperature zones, and electrical current between adjacent electrical flanges can be controlled so that the molten glass in the conduit is at a predetermined temperature between the adjacent flanges. As used herein, adjacent electrical flanges means a pair of electrical flanges, where there are no additional electrical flanges between the pair of adjacent flanges. However, an electrical flange can simultaneously function as one of a first pair of adjacent electrical flanges and one of a second pair of adjacent electrical flanges. Although FIG. 4 shows two electrical flanges 82 joined to the fining vessel 134, the fining vessel 134 can also include more than two electrical flanges, such as three electrical flanges, four electrical flanges, five electrical flanges, or six or more electrical flanges. Electrical currents of the same or different magnitudes can be established between each pair of adjacent electrical flanges so that each section of the fining vessel can be controlled to a different temperature.

[0051] The fining vessel 134 further includes at least one reinforcing member 146 attached to the exterior surface of the fining vessel wall 136. The reinforcing member functions to support the upper portion of a conduit, such as the fining vessel, and to prevent collapse of the conduit over time as it operates at high temperatures. The at least one reinforcing member 146 can be a hollow metal tube attached to the fining vessel wall, such as by welding. The weld need not be continuous. For example, the at least one reinforcing member can be spot welded or stitch welded, with spots or short sections of weld separated by gaps in the weld. The reinforcing member can be perpendicular to the central longitudinal axis 148 of the fining vessel 134 (see FIG. 5). The at least one reinforcing member 146 can be formed from a precious metal. Suitable precious metals include platinum group metals selected from the group consisting of platinum, iridium, rhodium, osmium, ruthenium, and palladium, or alloys thereof. For example, at least one reinforcing member 146 can be formed from a platinum-rhodium alloy including between about 70% and about 90% platinum and between about 10% and about 30% rhodium by weight.

[0052] At least one reinforcing member 146 can extend partially or completely around the fining vessel. For example, assuming a fining vessel having a circular cross-sectional shape, in such a situation, at least one reinforcing member 146 can include a circular reinforcing member attached to the exterior surface of the fining vessel wall 136 that extends completely around the fining vessel 134 (FIG. 5) or an arc that extends around a portion of the fining vessel 134 (FIGS. 6-7). If the fining vessel 134 has a non-circular cross-sectional shape, then at least one reinforcing member 146 can have a similar, complementary shape to the fining vessel. For example, if the periphery of the fining vessel 134 has an oval shape, then the shape of the inner periphery of at least one reinforcing member 146 can also be oval.

[0053] In the example where the at least one reinforcing member 146 extends around a portion of the fining vessel 134, as shown in Figure 7, the at least one reinforcing member 146 can be an arc shape (for a circular fining vessel) that defines an angle α (relative to the central longitudinal axis 148 or equivalent) secured to the outer surface of the fining vessel wall by welding. As shown in Figures 6-7, the at least one reinforcing member is disposed over and along the top of the fining vessel. The angle α can be within a range of about 360 degrees to about 180 degrees, disposed symmetrically about top dead center (TDC) of the fining vessel 134.

[0054] Figure 8 illustrates various non-exclusive cross-sectional shapes suitable for the at least one reinforcing member 146. For example, the at least one reinforcing member 146 can be a U-shaped channel having a rectangular or substantially rectangular cross-sectional shape as shown in view (a) of Figure 8, which is attached to the fining vessel wall 136 with the channel side of the reinforcing member facing the fining vessel wall, thereby forming a hollow interior in the reinforcing member. View (b) of Figure 8 illustrates another reinforcing member that is a box-shaped tube with four orthogonal sides defining a hollow interior and attached along one side to the fining vessel wall. The box-shaped tube can be a rectangular tube or a square tube. As shown in view (c) of Figure 8, the at least one reinforcing member can be a hollow cylindrical tube (i.e., having a circular cross-sectional shape). The hollow cylindrical tubes can be attached to the fining vessel wall by a pair of side plates 148 that run parallel to the hollow cylindrical tubes, with each side plate 148 welded to the fining vessel 134 along a first edge of the side plate and welded to the hollow cylindrical tube along an opposing second edge of the side plate. The width from the first edge to the second edge of each side plate 148 can be used to control the distance between the hollow cylindrical tubes and the fining vessel 134. For example, the hollow cylindrical tubes can be placed in direct contact with the fining vessel 134 as shown in view (c) of FIG. 8. Alternatively, the hollow cylindrical tubes can be spaced from the fining vessel by a gap 150 as shown in view (d) of FIG. 8. Alternatively, view (e) of FIG. 8 shows a hollow cylindrical tube welded directly to the fining vessel without the use of side plates 148. 8 views (a)-(e) show several exemplary reinforcing member cross-sectional shapes suitable for reinforcing the fining vessel 134, other shapes are contemplated including, without limitation, elliptical or oval cross-sectional shapes and polygonal cross-sectional shapes having less than four sides (e.g., triangular cross-sectional shapes) or more than four sides (e.g., pentagonal, hexagonal, heptagonal, octagonal, etc.). Any one of these various cross-sectional shapes can be attached to the fining vessel 134 using side plates 148 with or without gaps 150.

[0055] Additionally or alternatively, at least one reinforcing member 146 attached to the fining vessel 134 can be a solid reinforcing member having a cross-sectional shape similar or identical to that described with respect to views (a)-(e) of Figure 8. For example, views (a)-(f) of Figure 9 show (a) a rectangular (e.g., square) member, (b) a cylindrical bar attached with a plate with no gap to the conduit wall, (c) a cylindrical bar attached with a plate with a gap to the conduit wall, (d) a cylindrical bar attached without a plate, (e) a "T" shaped reinforcing member, and (f) an "I" shaped reinforcing member, any one or more of which can be substituted for a hollow reinforcing member. The reinforcing members can also be hybrid, with at least one reinforcing member being hollow and at least one reinforcing member being solid. Other shapes are also contemplated, including without limitation elliptical or oval cross-sectional shapes, and polygonal cross-sectional shapes having less than four sides (e.g., triangular cross-sectional shapes) or more than four sides (e.g., pentagonal, hexagonal, heptagonal, octagonal, etc.). The fining vessel 134 can be fitted with any one of these various solid cross-sectional shapes using side plates 148, with or without gaps 150.

[0056] To prevent over-pressurization of the at least one reinforcing member due to expansion of gas within the hollow interior of the reinforcing member, such as during heating of the fining vessel 134, the at least one reinforcing member 146 may include one or more pressure equalization orifices 152 extending between the hollow interior of the reinforcing member and the outside atmosphere. Over-pressurization of the at least one reinforcing member 146 may result in rupture of the reinforcing member and damage to the fining vessel 134. If the reinforcing member does not extend all the way around the fining vessel, the ends of the reinforcing member are open and the pressure equalization orifices may include the open ends of tubes or channels (if the reinforcing member includes a U-shaped member and stitch or spot welding is used and the weld gap extends between the hollow interior of the U-shaped member and the atmosphere outside the reinforcing member, the pressure equalization orifices may include the weld gap).

[0057] 9, the fining vessel 134 can include creases (e.g., corrugations, crimps) 154 that extend around the periphery of the fining vessel wall 136. The creases 154 can provide additional support to the fining vessel wall to prevent the top of the wall from collapsing. Each crease can extend around the entire periphery of the fining vessel 134.

[0058] The number and dimensional characteristics of the at least one reinforcing member 146 depend on the structural characteristics of the conduit (e.g., fining vessel 134) to which the at least one reinforcing member is attached. For example, the number and dimensional characteristics of the at least one reinforcing member 146 may depend on the length of the conduit, the thickness of one or more walls of the conduit, the diameter of the conduit, the physical support provided to the conduit by anchors or other support structures such as firebricks or blocks, and the amount of deformation (e.g., downward displacement of the top of the conduit) that can be tolerated. As shown in FIG. 10, the fining vessel 134 (or any other conduit, such as a connecting conduit) may be supported by a refractory material disposed around the conduit. For example, the conduit may be placed within a refractory sheet, a refractory blanket, a refractory block, a castable refractory material (which is poured as a slurry and then hardens around the conduit), or any combination of these support materials. Such support materials may include mullite, insulating refractory bricks, and insulating boards (e.g., Fiberfrax® Duraboard® 3000) and are positioned to help control heat loss from the conduit. FIG. 10 shows the fining vessel 134 supported by refractory blocks 160, although other forms of refractory materials may be used in addition or instead, as discussed above. However, the use of reinforcing members 146 may prevent collapse of the conduit in the absence of supporting refractory material. Thus, to allow the conduit to move within the refractory material during thermal expansion, a gap may be provided between the refractory material and the walls of the conduit, avoiding the use of form-fitting, non-conformable refractory materials. This gap allows free movement of the conduit and reinforcing members within the surrounding refractory material, as may occur during thermal expansion or contraction of the conduit.

[0059] The at least one reinforcing member 146 can include multiple reinforcing members. For example, the fining vessel 134 can have at least two reinforcing members attached thereto, such as three reinforcing members, four reinforcing members, five reinforcing members, six reinforcing members, or more than six reinforcing members. The multiple reinforcing members 146 can be equally or unevenly spaced from one another. There can be a first multiple reinforcing members attached to the fining vessel 134 between a first adjacent pair of electrical flanges 82, a second multiple reinforcing members attached to the fining vessel 134 between a second adjacent pair of electrical flanges 82, and a third multiple reinforcing members 146 attached to the fining vessel 134 between a third adjacent pair of electrical flanges 82, and so on.

[0060] The reinforcing member 146 disclosed herein is spaced from the electrical flange and therefore plays little, if any, role in the distribution of current within the finer wall 136. Modeling has shown that the presence of a reinforcing member spaced from the electrical flange does not affect the current density within the finer wall and therefore does not affect the heat generation within the finer wall. Figures 11A-11B show modeled finer temperatures without (Figure 11A) and with (Figure 11B), respectively, all other conditions remaining the same. As is readily apparent, there is no distinguishable difference between the two temperature distributions. Similarly, Figures 12A-12B show modeled finer current density without (Figure 12A) and with (Figure 12B), respectively. Again, there is no distinguishable difference between the two current density distributions. Thus, the presence of a reinforcing member spaced from the electrical flange does not change the temperature of the finer vessel and therefore the molten glass conveyed therein. In other words, in some glass manufacturing apparatus, the fining vessel may include a thick wall portion that abuts the electrical flange. For example, the electrical flange may be connected to a current source by an electrode portion that extends from the body of the electrical flange. The current enters the fining vessel wall through the electrode portion and follows the shortest electrical path through the fining vessel wall unmitigated. For example, if the electrode portions are positioned to extend from the top of the electrical flange, the shortest electrical path between two adjacent electrical flanges crosses the top of the fining vessel. As mentioned above, the fining vessel utilizes a gaseous atmosphere within the fining vessel (above the molten glass). Because the gaseous atmosphere within the fining vessel has a lower heat capacity and lower thermal conductivity than the molten glass, high current densities at the top of the fining vessel may overheat the top of the fining vessel and degrade the fining vessel wall. Thus, the thick wall portion of the fining vessel positioned against the electrical flange may be used to redistribute the current within the fining vessel wall, thus reducing the temperature at the top of the fining vessel wall. The reinforcing member 146 is spaced from the electrical flanges so that it has no effect on conducting electrical current and / or affecting the temperature of the fining vessel. Typically, the reinforcing member 146 disclosed herein can be located in the center portion of the fining vessel between two adjacent electrical flanges, such as between adjacent electrical flanges, and spaced from the electrical flanges.

[0061] Although the reinforcing members disclosed herein have been described primarily with respect to fining vessels, the disclosed reinforcing members 146 in all of their various shapes and configurations can be used on any collapsible metal conduit configured to carry molten glass, including whether or not there may be electrical flanges on the conduit. For example, the disclosed connecting conduits 32, 36 and 46 can all be equipped with reinforcing members 146.

[0062] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure, and therefore, the present disclosure is intended to cover such modifications and variations, provided they come within the scope of the appended claims and their equivalents. [Explanation of symbols]

[0063] 82 Electrical flange 134 Clarifying vessel 146 Reinforcement members 148 Central Longitudinal Axis

Claims

1. A glass forming apparatus comprising: a conduit including an internal passage configured to convey a flow of molten glass; at least one reinforcing member attached to and extending around at least a portion of an outer periphery of the conduit, the at least one reinforcing member being positioned between and spaced apart from a pair of adjacent electrical flanges; A glass forming device comprising:

2. the at least one reinforcing member extends around an upper portion of the conduit; The glass forming apparatus according to claim 1 .

3. the at least one reinforcing member extends circumferentially around the conduit; The glass forming apparatus according to claim 1 .

4. the at least one reinforcing member includes a hollow interior; The glass forming apparatus according to claim 1 .

5. the reinforcing member includes a pressure equalizing orifice that provides fluid communication between a hollow interior of the reinforcing member and an atmosphere external to the reinforcing member; The glass forming apparatus according to claim 4.

6. the conduit comprises platinum; The glass forming apparatus according to claim 1 .

7. the at least one reinforcing member comprises platinum; The glass forming apparatus according to claim 1 .

8. the conduit comprises a fining vessel; The glass forming apparatus according to claim 1 .

9. the at least one reinforcing member is attached to the conduit by a plate; The glass forming apparatus according to claim 1 .

10. the at least one reinforcing member is spaced from the conduit by a gap; The glass forming apparatus according to any one of claims 1 to 9.

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