Apparatus and method for making glass
阅读说明:本技术 制造玻璃的设备和方法 (Apparatus and method for making glass ) 是由 安格利 G·德 M·A·德拉米勒 M·H·戈勒尔 S·克里西那莫西 G·K·施文克 于 2014-10-14 设计创作,主要内容包括:公开了一种包含澄清容器的熔融玻璃递送设备,该澄清容器包含壁,其中,该澄清容器的壁厚沿周向变化。在一些实施方式中,在澄清容器内与气态气氛接触的澄清容器上部部分比该澄清容器的与熔融玻璃接触的剩余部分更薄。还公开了一种使熔融玻璃澄清的方法。(A molten glass delivery apparatus is disclosed comprising a fining vessel comprising a wall, wherein the wall thickness of the fining vessel varies circumferentially. In some embodiments, the upper portion of the fining vessel that is in contact with the gaseous atmosphere within the fining vessel is thinner than the remaining portion of the fining vessel that is in contact with the molten glass. A method of fining molten glass is also disclosed.)
1. A molten glass delivery apparatus, comprising:
a container comprising a wall comprising a first wall portion disposed at a top of the container and a second wall portion disposed at a bottom of the container;
a first flange surrounding the vessel and a second flange surrounding the vessel, the second flange being spaced apart from and continuous with the first flange, the first and second flanges being configured to conduct electrical current through the wall between the first and second flanges, the first and second flanges each further comprising an electrode extending therefrom and closest to the first wall portion, the first wall portion comprising a first length portion and a second length portion, the second length portion abutting the second flange;
wherein in a first cross section of the wall containing the first length portion the thickness of the first length portion is less than the thickness of the second wall portion and in a second cross section of the wall containing the second length portion the thickness of the second length portion is greater than the thickness of the first length portion.
2. The molten glass delivery apparatus according to claim 1, wherein a thickness of the second wall portion is greater than a thickness of the second length portion.
3. The molten glass delivery apparatus according to claim 2, wherein the first wall portion further includes a third length portion adjacent the first flange and spaced apart from the second length portion, and wherein in the third cross-section including the third length portion, a thickness of the third length portion is equal to a thickness of the first length portion.
4. The molten glass delivery apparatus according to claim 3, wherein the second wall portion is laminated and comprises a first metal layer and a second metal layer.
5. The molten glass delivery apparatus according to claim 4, wherein the metal of the second metal layer is different from the metal of the first metal layer.
6. The molten glass delivery apparatus according to claim 1, wherein a thickness of the second wall portion is uniform.
7. The molten glass delivery apparatus according to claim 1, wherein the vessel is a fining vessel.
8. The molten glass delivery apparatus according to claim 1, wherein the wall comprises platinum, rhodium, palladium, iridium, ruthenium, osmium, or alloys thereof.
9. The molten glass delivery apparatus according to any one of claims 1-7, wherein the first flange and the second flange comprise a metal of platinum, rhodium, palladium, iridium, ruthenium, osmium, or alloys thereof.
Technical Field
Melting raw materials to form a molten material (hereinafter referred to as molten glass) requires the use of combustion gases and/or electrical energy during the melting process. The raw material may then be conditioned and transported from the furnace to the forming apparatus. In some processes, molten glass is delivered to a forming apparatus by a precious metal delivery apparatus comprising various processing equipment. To ensure a controlled temperature, certain components of the delivery apparatus may be directly heated by generating an electrical current in those components. The electric current heats the assembly, which in turn heats the molten glass therein. Different components of the delivery device have different energy requirements. The most power demanding component of the delivery apparatus is perhaps the fining vessel in which the molten glass is conditioned to remove gases generated in the melting process.
The fining vessel is maintained at a very high temperature in order to effectively remove bubbles after the melting process and to ensure the breakdown of any solid particles escaping from the furnace. The bubbles rise faster at lower viscosities and the solid inclusions decompose faster at higher temperatures. The top of the clarifier has an air gap. Unfortunately, noble metals (e.g., platinum and/or rhodium) can oxidize in the presence of oxygen, and the rate at which oxidation occurs increases with temperature and oxygen content. Oxidation of the noble metal results in thinning of the metal. Oxidation is generally more severe at the top of the fining vessel for at least two reasons: 1) an air gap exists above the surface of the molten glass; and 2) the temperature at the top of the fining vessel is highest. For some glasses, the temperature at the top of the fining vessel may exceed 1700 ℃. Typically, the temperature at the top of the fining vessel may be 20 ℃ higher on average than the temperature of the molten glass remaining in the lower portion of the fining vessel. Because higher temperatures at the top of the fining vessel can lead to corrosion failure of the fining vessel, it is desirable to reduce the top temperature within the fining vessel.
Summary of The Invention
The ability of the molten glass manufacturing process to produce thin glass sheets with surface qualities beyond those expected makes these glass sheets ideal for the manufacture of visual display products such as televisions, cell phones, computer monitors, and the like. In a typical fusion process, raw materials (formed into batches) are melted in a refractory ceramic melting furnace to produce molten glass. The molten glass is then delivered to the forming body by a delivery apparatus. The forming body includes a groove formed in an upper surface thereof, and an outer converging forming surface. Molten glass is received from a delivery device by a trough from which it overflows and flows downwardly in separate streams over converging forming surfaces. The separate streams combine where the converging forming surfaces meet to form a single glass ribbon that is cut into individual glass sheets once it has cooled to an elastic solid.
Although the furnace and the forming body are mostly made of refractory ceramic materials, the delivery device for delivering the molten glass to the forming body is generally made using high temperature metals, in particular oxidation resistant high temperature metals. Suitable metals may be selected, for example, from the platinum group metals, i.e., platinum, iridium, rhodium, palladium, osmium, and ruthenium. Alloys of the above platinum group metals may also be used. For example, molten glass delivery apparatus are often made from platinum or alloys of platinum (e.g., platinum-rhodium alloys) because platinum or alloys of platinum (e.g., platinum-rhodium alloys) are more easily physically processed than other platinum group metals.
When molten glass is delivered by a delivery apparatus, it can be conditioned by passing the molten glass through a conditioning vessel, such as a fining vessel, where the degassing process occurs. Various gases are formed during the melting process. If these gases remain in the molten glass, bubbles may be generated in the finished glass article, such as a glass sheet obtained by the fusion process. To eliminate bubbles in the glass, the temperature of the molten glass in the fining vessel is increased to a temperature above the melting temperature. Multivalent compounds contained in the batch materials and present in the molten glass release oxygen during temperature elevation and help sweep gases formed during the melting process of the molten glass. These gases are released into the fining vessel discharge space above the free surface of the molten glass. In some cases, such as the production of glass sheets for the display industry, the temperature in the fining vessel can exceed 1650 ℃, even 1700 ℃, and approach the melting temperature of the fining vessel walls.
One method of increasing the temperature in a fining vessel is to generate an electrical current in the fining vessel, where the temperature is increased by the resistance of the metal walls of the vessel. Such direct heating may be referred to as joule heating. To achieve this heating, electrodes (also called flanges) are connected to the fining vessel and act as the inflow and outflow points for the electrical current.
Monitoring of the fining vessel temperature at various locations within the fining vessel may be accomplished by embedding thermocouples in the refractory and insulating material surrounding the fining vessel. This monitored data shows an increase in temperature in the fining vessel at the gaseous atmosphere above the free surface of the molten glass in contact with the walls of the fining vessel. This may be attributed to a reduction in the thermal conductivity of the gaseous atmosphere within the fining vessel relative to the thermal conductivity of the molten glass contained within lower portions of the fining vessel. A cross-section of a scrapped fining vessel shows excessive oxidation of the upper portion of the fining vessel not in contact with the molten glass, particularly where the flange meets the fining vessel wall. This oxidation occurs due to the high temperature of the metal in the presence of oxygen. Unfortunately, it is difficult to completely eliminate oxygen from the environment surrounding the fining vessel. In addition, this oxidation can gradually thin the vessel wall metal in regions of the vessel where molten glass does not flow, eventually leading to failure of the vessel wall. Accordingly, embodiments disclosed herein relate to controlling the flow of electrical current through a fining vessel wall to reduce the temperature of the portion of the wall where the wall is in contact with the gaseous atmosphere within the fining vessel and where the molten glass does not flow.
In one aspect, a delivery apparatus for molten glass is disclosed, comprising: a fining vessel configured as a tube comprising a wall, the wall of the tube comprising a metal selected from the group consisting of platinum, rhodium, palladium, iridium, ruthenium, osmium, and alloys thereof; a plurality of flanges surrounding the tube and configured to conduct electrical current through the wall, the plurality of flanges comprising platinum, rhodium, palladium, iridium, ruthenium, osmium, and alloys thereof. At least a portion of the wall between at least two consecutive flanges of the plurality of flanges comprises a circumferentially varying thickness. The term "two continuous flanges" is intended to mean that the molten glass passes through the two continuous flanges in sequence, without an intervening flange between the two continuous flanges, in the direction of flow of the molten glass.
The at least a portion of the wall may include a first wall portion and a second wall portion, and a thickness of the first wall portion may be less than a thickness of the second wall portion at a cross section of the at least a portion of the wall. The thickness of the first wall portion may be substantially uniform and the thickness of the second wall portion may be substantially uniform. The first wall portion is located at the top of the fining vessel and the second wall portion is located at the bottom of the fining vessel, with the second wall portion being below the first wall portion.
The molten glass delivery apparatus can also include a third wall portion located between the first wall portion and the second wall portion. The thickness of the third wall part at said cross section may be greater than the thickness of the second wall part.
The second wall portion may be made to comprise a plurality of layers. For example, the second wall portion may comprise a laminated structure comprising a plurality of metal plates.
In another embodiment, the at least a portion of the fining vessel wall can comprise a first wall portion and a second wall portion, wherein the first wall portion has a thickness greater than a thickness of the second wall portion. The first wall portion is located at the top of the fining vessel and the at least a portion of the wall may be located adjacent to one of the two continuous flanges.
The thickness of the first and/or second wall portion may be substantially uniform.
In some embodiments, when the first wall portion is thicker than the second wall portion, the length of the first wall portion may be no greater than about 16 cm.
The first wall portion may comprise a plurality of metal layers when the first wall portion is thicker than the second wall portion. According to some aspects of this embodiment, the first wall portion abuts one of the two continuous flanges. In other aspects, a flange may be attached to an upper surface of the first wall portion, such as to a central portion of the first wall portion, such that the first wall portion extends outwardly from the flange parallel to the longitudinal axis of the fining vessel. In one example, the first section has a length of 16cm along the longitudinal axis of the fining vessel, and the flange is connected to the first section at a midpoint of the 16cm length. It should be apparent from the above description that the length may be other than 16cm, for example less than 16cm, with the flange being connected to the first wall portion at a midpoint of its length.
The at least a portion of the wall may include a first length portion, a second length portion spaced apart from the first length portion, and a third length portion located between the first and second length portions. The thickness of the first length portion may vary circumferentially, the thickness of the second length portion may vary circumferentially, and the thickness of the third length portion may be substantially constant. Additionally, the first and second length portions may each include a first wall portion and a second wall portion, and the first wall portions of the first and second length portions may have a thickness greater than the thickness of the second wall portions of the first and second length portions. The first wall portions of the first and second length portions may be located at the top of the fining vessel.
Each of the first and second length portions may be located adjacent to one of the two continuous flanges such that each of the first and second length portions abuts a respective one of the two continuous flanges.
The molten glass delivery apparatus may also include a fourth length between adjacent flanges, the fourth length including a first wall portion and a second wall portion, the first wall portion of the fourth length being located at the top of the fining vessel. The thickness of the first wall portion of the fourth length portion may be greater than the thickness of the second wall portion of the fourth length portion.
In another embodiment, a method of forming glass is disclosed that includes melting batch materials in a furnace; flowing molten glass from a furnace through a metal fining vessel such that the molten glass includes a free surface within the fining vessel and an atmosphere is between the fining vessel and the free surface, the fining vessel including a wall including a first wall portion including a first thickness and a second wall portion including a second thickness such that, in cross-section, the first thickness is different than the second thickness. The flow of the molten glass is controlled so that the stream of the molten glass does not flow over the surface of the upper wall portion. The first wall portion is therefore located at the top of the fining vessel and the second wall portion is located at the bottom of the fining vessel.
The first thickness may be less than the second thickness, or the first thickness may be greater than the second thickness.
In some embodiments, the fining vessel may comprise a third wall portion located between the first wall portion and the second wall portion, the third wall portion comprising a third thickness greater than the first thickness and the second thickness at the cross-section. The level of molten glass in the fining vessel can be controlled such that the free surface intersects the third wall portion.
The temperature of the first wall portion may be, for example, at least 5 degrees celsius (° c) lower than the temperature of the second wall portion.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description describe embodiments of the invention and are intended to provide an overview or framework for understanding the nature and character of the embodiments as they are claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operations of these embodiments.
Brief description of the drawings
FIG. 1 is a front view of an exemplary fusion downdraw glass manufacturing apparatus including a fining vessel according to embodiments described herein;
FIG. 2 is a perspective view of the fining vessel of FIG. 1;
FIG. 3 is a cross-sectional view of a prior art fining vessel including a wall with a circumferentially uniform thickness;
FIG. 4 is a photograph of a corrosion failure of a clarifying vessel wall;
FIG. 5 is a cross-sectional view of a fining vessel according to embodiments described herein, wherein the wall thickness of the fining vessel wall varies circumferentially;
FIG. 6 is an electrical schematic illustrating the effect depicted in FIG. 5;
FIG. 7 is a cross-sectional view of another embodiment of a fining vessel as described herein, wherein the wall thickness of the fining vessel varies circumferentially such that the upper wall portion is thinner than the lower wall portion, and the lower wall portion comprises multiple layers;
FIG. 8 is a cross-sectional view of another embodiment of a fining vessel as described herein, wherein the wall thickness of the fining vessel varies circumferentially with an intermediate wall portion disposed between the upper and lower wall portions;
FIG. 9 is a side view of a fining vessel including both thin portions and thick portions in the upper portion of the fining vessel;
FIG. 10 is a cross-sectional view of the fining vessel of FIG. 9, wherein the cross-section shown is taken at a thick portion of the upper wall portion;
FIG. 11 is a cross-sectional view of the fining vessel of FIG. 9, wherein the cross-section shown is taken at a thin portion of the upper wall portion;
FIG. 12 is an electrical schematic illustrating the effect of including a thin upper wall portion and a thick upper wall portion in a fining vessel;
FIG. 13 is a side view of a fining vessel including a thin upper wall portion located between two thick upper wall portions;
FIG. 14 is a side view of a fining vessel illustrating an upper wall portion, a lower wall portion, the upper and lower wall portions being positioned between two consecutive flanges, wherein the upper wall portion is thinner than the lower wall portion and the electrodes interfacing with the flanges extend upwardly from near the upper portion of the top of the fining vessel;
FIG. 15 is a cross-sectional view of a fining vessel according to an embodiment in which the flange electrode extends downward from a position on the flange closest to the bottom of the flange;
FIG. 16 is a cross-sectional view of a fining vessel according to an embodiment in which the flange electrode extends downward from a position on the flange closest to the bottom of the flange;
FIG. 17 is a graph of modeled and actual temperature as a function of length along a fining vessel with the temperature at the top of the fining vessel being substantially higher than the temperature of other portions of the fining vessel having a wall with a substantially uniform thickness circumferentially at a cross-section of the fining vessel;
FIG. 18 is a side view of a fining vessel modeled by the curves of FIG. 17;
FIG. 19 is a graph modeling current density as a function of length along the fining vessel of FIGS. 17 and 18;
FIG. 20 is a graph illustrating modeled temperature as a function of length along a fining vessel, the fining vessel including an upper wall portion, a lower wall portion, and the upper wall portion having a thickness that is less than a thickness of the lower wall portion; and
FIG. 21 is a graph showing the modeled current density of the fining vessel of FIG. 20 as a function of length.
Detailed Description
As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "flange" includes aspects having two or more such flanges, unless the context clearly indicates otherwise.
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 aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. When a range is expressed as "between" one value and another value, the one value and the other value denote the endpoints of the range, and are included in the range.
As used herein, the terms "having" and "including" are open-ended terms and do not exclude the presence of other properties, features, attributes or elements, unless specifically stated otherwise.
As used herein, the term "circumferentially" is generally construed to refer to angular position about the perimeter of a cross-section and is not limited to a circular cross-section, and thus, the phrase that the thickness varies circumferentially means that the thickness of a cross-section of an article (e.g., fining vessel) wall varies about the variation of angular position of the fining vessel relative to the longitudinal axis and is not limited to circular (cylindrical) fining vessels.
As used herein, an angle subtended by an arc, line or other curve refers to the angle formed by two rays passing through the ends of the arc.
As used herein, the term "vessel" should be understood to include a trough, conduit, pipe, or other structure through which molten glass may be contained and flowed.
In the exemplary
The molten glass is heated above T in fining
Although the
As noted above, molten glass is at elevated temperatures, and thus, delivery apparatus components require "high temperature" materials, such as materials capable of withstanding temperatures in excess of at least 1500 ℃ for extended periods of time. In addition, the material should be resistant to oxidation, which can be accelerated by high temperatures in the presence of oxygen. In addition, the molten glass can be quite corrosive, and therefore the material should be relatively resistant to attack by the glass, which can result in contamination of the finished glass article by the container material. Metals including the platinum group metals of the periodic table-platinum, rhodium, iridium, palladium, ruthenium, osmium, and alloys thereof-are particularly useful for this purpose, and because platinum is easier to process than other platinum group metals, many high temperature processes use containers of platinum or platinum alloys. One common platinum alloy is a platinum-rhodium alloy. However, because such precious metals are expensive, all effort has been made to minimize the size of these vessels to reduce the weight of the metal used.
To extract the most gas from the molten glass in the fining vessel, the molten glass is raised to a fining temperature T2. Heating of the molten glass may be initiated within connecting
To ensure a substantially uniform current flow in the fining vessel, care is taken in the design of
FIG. 2 illustrates a perspective view of at least a
Fig. 3 shows a cross-section of an exemplary fining vessel including a longitudinally closed
To reduce heat loss from fining
It should be appreciated that the corrosion process described above is typically a local event and depends at least on the local current density and oxygen concentration. That is, this corrosion does not occur uniformly over the entire wall surface, even when only the portion of the fining vessel wall that is in contact with the gaseous atmosphere above the free surface of the molten glass is considered. Moreover, since the local based oxygen concentration may be difficult to control, one idea is to control the current density and thus the temperature of the fining vessel wall.
Therefore, fining
In the embodiment of fig. 5, the thicker lower
FIG. 6 illustrates the first resistance element REaAnd a second resistance element REbSchematic diagram of the electrical appliance. Resistance element REaComprising a length LaCross-sectional area AaAnd resistivity ρa. Resistance element REbComprising a length LbCross-sectional area AbAnd resistivity ρb. The individual resistance elements can be imagined as, for example, cylindrical, solid and homogeneous wires. As shown in FIG. 6, the resistance element REaAnd REbAre connected in parallel between the two
The previous example assumes a resistive element REaAnd a resistance element REbThe same is true. Now assume that resistive element REaIs reduced so that A isa<AbOther conditions are the same as in the above example. That is, assume that the resistance element REaIs in accordance with the previous exampleThe wires in (1) are the same wires, but thinner. This is equivalent to, for example, reducing the thickness of the
The preceding simple example illustrates that making the thickness of the upper wall portion of fining vessel 20 (i.e., the portion of the fining vessel wall in contact with the gaseous atmosphere above the free surface of the molten glass) thinner relative to the thickness of the lower wall portion (i.e., the portion of the fining vessel wall in contact with the molten glass) reduces the current in the upper wall portion of the fining vessel and thus also reduces the temperature of the upper wall portion. The service life of the fining vessel can be greatly extended even if the temperature is reduced by only a few degrees celsius. Because of the distribution of the increase in current in the lower portion over a much larger cross-sectional area (the lower portion is much larger and much thicker than the upper portion), the increase in current in the lower portion may have only a negligible effect (only a negligible increase in current density).
It should be noted that the above description by means of circuit diagrams is over-simplified, at least for the following reasons: the upper and lower wall portions of the fining vessel are not separate elements but are continuous. The electrical analysis of a real fining vessel is much more complex. However, use is made of
Computer analysis of the computational software has confirmed the results obtained. Therefore, the foregoing description is considered as illustrative of the principles.In some embodiments, the upper or
In another embodiment, as shown in FIG. 8, fining
A cross-section of a scrapped fining vessel also shows that oxidative corrosion of the fining vessel tends to begin more often at or near the location where the flange joins the upper or
Fig. 9 illustrates a fining
Reviewing for comparison purposes, FIG. 6 illustrates the first resistive element REaAnd a second resistance element REbSchematic diagram of the electrical appliance. Resistance element REaComprising a length LaCross-sectional area AaAnd resistivity ρa. Resistance element REbComprising a length LbCross-sectional area AbAnd resistivity ρb. Each of the resistive elements may be, for example, a wire. As shown in FIG. 6, the resistance element REaAnd REbIn parallel between the two
The previous example assumes a resistive element REaAnd a resistance element REbThe same is true. Now thatReferring to fig. 12, it is assumed that the resistance element REaA cross-sectional area of a part of (b) is increased, thereby the resistance element REaComprising two sections. That is, assume that the resistance element REaIncludes two resistive element sections, a first resistive element section REa1And a second resistive element segment REa2。REa1Comprising a length La1Sectional area Aa1Resistivity rhoa1And a resistance Ra1。REa2Comprising a length La2Sectional area Aa2Resistivity rhoa2And a resistance Ra2. Further assume that the first resistive element segment REa1Length L ofa1Is more than the second resistance element section REa2Length L ofa2Much longer and second resistive element segment REa2Cross-sectional area A ofa2Larger than the first resistive element segment REa1Cross-sectional area A ofa1. In other words, it is assumed that the first resistance element REaComprising two sections arranged in series at their ends, wherein the second section has a thickness greater than the thickness of the first section, but the length of the first section is much longer than the length of the second section. Assuming the resistivities of the two sections and the second resistive element RE2So that ρ is equala1=ρa2=ρb. Thus, RE can be showna1Can control REa(as an example of a specific value, consider that for two series-connected resistive elements, one of which has a resistance of 100 ohms and the second of which has a resistance of 5 ohms, the total resistance of the two series-connected resistive elements is 105 ohms, which is not much different from the resistance of the 100 ohm resistive element).
Thus, in this example, the first resistive element REaTotal resistance of (2) ═ Ra=Ra1+Ra2First resistance element REaCurrent I ina=E/Ra=E/(Ra1+Ra2),Ib=E/Rb. Represents a segment REa1And REa2Legs of, i.e. resistive elements REaCurrent I inaCan pass through E/Ra1Roughly determined. Current IbElectricity that would be relevant in figure 6Stream IbThe same is true. However, the current I of the present embodimentaWill be in the second resistive element section REa2Cross-sectional area A ofa2Upper distribution, cross-sectional area Aa2Larger than the first resistive element segment REa1Cross-sectional area A ofa1. Therefore, for the second resistance element section REa2Will be less heated than the first resistive element segment REa1So that the second resistive element segment REa2Will be lower than the first resistive element section REa1The temperature of (2). In the case of fining
In another embodiment shown in fig. 13, the
The cause of hot spots at the
FIG. 14 illustrates a side view of a fining vessel including a wall with a thickness that varies circumferentially.
To mitigate high current densities in the upper portion of the fining vessel, an
Examples
FIG. 17 illustrates a graph of temperature along a length of a fining vessel including a substantially uniform cross-sectional wall thickness along the circumferential direction. In addition, as shown in FIG. 18, the fining vessel further comprises a thickening band 75 located between the flanges, the thickening band 75 being adjacent to and abutting the second flange (the rightmost flange in the figures) and extending longitudinally along the fining vessel a distance of about 11 cm. The thickening belt surrounds the clarifying container and has a thickness greater than the wall residue of the clarifying containerThe thickness of the remainder, but the thickness of the thickening belt itself, is substantially uniform. The flanges are located at positions a and B. Curves 70, 72 and 74 represent
The software generated modeling data, circles and triangles represent actual data obtained on the fining vessel by a thermocouple embedded in the refractory insulating material surrounding the fining vessel. The graph shows that the actual data generally mimics the modeled data, helping to demonstrate the feasibility of modeling the temperature along the length of the fining vessel.FIG. 20 illustrates temperature along the length of a fining vessel comprising an upper wall portion and a lower wall portion, wherein the upper wall portion has a smaller cross-sectional wall thickness than the lower wall portion, such as the fining vessel of FIG. 5. The fining vessel of fig. 20 does not contain a thickening belt. The length is shown as a normalized length and the temperature is shown in degrees Celsius (. degree. C.).
The graph shows that the current density is generally uniform around the circumference of the fining vessel as a result of the circumferential thickness varying between the two flanges over a medium length of the fining vessel (as indicated by the current densities at the top, bottom, and midpoint), but also shows that the current density rises at the flanges due to the presence of the flanges, as the flanges function to direct all of the current in the fining vessel into or out of the fining vessel.
Thus, these flanges may be considered as nodes that are pooled or distributed. The effect of this increased current density at the flange in the fining vessel, which ultimately results in a temperature increase, can be mitigated by including a thickened band as described above, or more preferably, by including a thick second upper portion, as the modeling results show, including a thickened band around the entire perimeter of the fining vessel does not have a significant effect on the temperature in the lower portion of the fining vessel. Thus, using a thin portion only in the upper portion of the fining vessel represents a cost savings over precious metals relative to increasing the thickness of the fining vessel around the entire circumference.
It should be noted that although the above embodiments are described in the context of a fining vessel, the principles and configurations disclosed herein may be applied to other vessels for delivering molten glass, regardless of the presence or absence of a free surface of molten glass within the vessel. For example, the principles and configurations disclosed herein may be applied, in part or in whole, to connecting
It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the spirit and scope of the embodiments of the invention. Thus, it is the intention of the inventors to cover modifications and variations of these embodiments, provided they come within the scope of the appended claims and their equivalents.
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