Continuous cold crown induction glass melter

Abstract

An induction glass melting system for producing glass comprising has a vertical melting tank to contain a batch material for melting and molten glass. The system also includes a batch material feeder for feeding the batch material to the melting tank at the top side of the melting tank, and a glass melt outlet for discharging a resulting glass melt at the bottom side of the melting tank. The system includes a multi-zone heating system with a plurality of induction coils around a periphery of the melting tank to independently heat a plurality of heating zones vertically along a height of the melting tank. The system includes in-situ monitoring and enables a continuous cold crown melting process.

Description

CONTINUOUS COLD CROWN INDUCTION GLASS MELTERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63 / 553,463 filed on February 14, 2024, the content of which are relied upon and incorporated herein by reference in their entirety.FIELD OF THE DISCLOSURE

[0002] This disclosure general relates to induction glass melting systems and methods, and in particular, to cold crown induction glass melting systems and methods for achieving continuous glass melting.BACKGROUND

[0003] Glass manufacturing is an energy- intensive industry. On average, the glass industry produces 0.6 tons CO2 emission per ton of glass product. There are generally two main sources of greenhouse gas emissions that companies seek to reduce through their sustainability efforts, sometimes referred to as Scope 1 and Scope 2 greenhouse gas emissions. Scope 1 includes direct greenhouse gas emissions from sources owned or controlled by a company. Scope 2 includes indirect greenhouse gas emissions from the generation of electricity, steam, heating, or cooling purchased by a company. Companies worldwide have pledged to reduce both categories of emissions. When it comes to melting glass batch material in glass manufacturing, there are two main technologies currently available to reduce emissions: hydrogen burners and all-electric glass melting.

[0004] Two categories of glass melting techniques include hot crown melting and cold crown melting. In hot crown melting, the glass is heated from above by gas burners and is also heated from below by, for example, electrodes. The batch is fed in from one end of a melting tank forming a pile of batch material on the glass melt that typically covers a small fraction of thesurface of the melt. In cold crown melting, there is no heating above the batch. The batch can be fed from above the melt and forms a batch blanket that covers the surface of the melt in a layer, which can, for example, range from about 6 to 12 inches thick.

[0005] From the standpoint of emissions reduction, all-electric cold crown melting has several advantages over hydrogen burners, especially if a renewable source of electricity is available. These advantages include adequate current safety protocols, energy savings, and a decrease in volatility of several glass constituents (and thus less waste). These advantages make cold crown melting an attractive technology from a carbon emissions reduction standpoint. While cold crown melting is not a new technology, it has historically not been used successfully for producing glass that requires more demanding quality specifications.

[0006] Achieving high throughput and high yield in cold crown melting, especially for glass with high quality specifications, requires development in batch design, equipment, and process. Thus, there is a need for improved all-electric cold crown melting technology capable of producing high quality glass at a high throughput.SUMMARY

[0007] According to an embodiment of this disclosure, an induction glass melting system for producing glass is provided. The induction glass melting system includes a melting tank comprising an outer wall extending vertically and configured to contain a batch material for melting and molten glass, the melting tank comprising a top side and a bottom side opposite the top side; a batch material feeder for feeding the batch material to the melting tank at the top side; a glass melt outlet for discharging a glass melt resulting from melting the batch material in the melting tank, the glass melt outlet being configured to discharge the glass melt at the bottom side; and a multi-zone heating system comprising a plurality of induction coils around a periphery of the melting tank and configured to independently heat a plurality of heating zones vertically along a height of the melting tank.

[0008] In certain aspects of embodiments, the plurality of heating zones comprises a batch material zone comprising a section along the height of the melting furnace configured for housing the batch material added to the melting tank by the batch material feeder. The batchmaterial zone comprises a section along the height of the melting furnace at which an interface between the batch material and the molten glass is designed to be disposed. The plurality of heating zones also comprises a molten glass zone disposed between the batch material zone and the glass melt outlet. The molten glass zone comprises a section along the height of the melting furnace configured for housing the molten glass. The plurality of heating zones also comprises a downcomer zone disposed between the molten glass zone and the glass melt outlet. Thus, the batch material zone is disposed vertically above the molten glass zone, the downcomer zone is disposed vertically below the molten glass zone, and the molten glass zone is disposed vertically between the batch material zone and the downcomer zone.

[0009] According to additional aspects of embodiments, the outer wall of the melting furnace comprises an inductive wall material configured to be inductively heated by the multi-zone heating system, and the inductive wall material is configured to heat the batch material and / or the molten glass inside the melting tank. The outer wall may comprise an inner liner comprising the inductive wall material. In aspects, the inductive wall material comprises platinum. In certain aspects of embodiments, the melting furnace comprises an upper cold zone above the batch material zone, wherein the upper cold zone is not directly heated by a heating element in or surrounding the upper cold zone. The upper cold zone can comprise a crucible comprising fused silica, quartz, or platinum. The induction melting furnace system can be configured to be a continuously fed with batch material.

[0010] In further aspects of embodiments, the system further comprising one or more temperature sensors. The temperature sensors can include a thermocouple configured to measure a temperature of at least one of the batch material and the molten glass within the glass furnace. The system can further comprise a thermocouple sheath disposed at least partially within the melting tank and extending in a direction parallel to the vertical length of the melting tank, the thermocouple sheath comprising a hollow tube sized to fit the thermocouple within the hollow tube. The thermocouple is configured to move within the hollow tube to temperature readings at different heights within the melting tank. The thermocouple sheath can also be configured to move vertically within the melting tank. The thermocouple sheath comprises alumina. Additional aspects of embodiments include a hot spot thermocouple disposed at a vertical position of themelting tanks that corresponds to highest temperature of the molten glass during a continuous melting process. The hot spot thermocouple can be stationary. Additional temperature sensors can be disposed at at least one of the hot spot, the bottom of the molten glass zone, and the bottom of the downcomer zone where glass exits the downcomer.

[0011] According to aspects of embodiments, the batch material feeder comprises a batch feed tube comprising an outlet arranged near the top of the melting tank and an opening upstream of the outlet, wherein the opening is configured to allow heat emanating from the melting tank and / or vapor to escape from the batch feed tube before reaching a source of the batch material. A passive batch material distributor may be disposed between the batch material feeder and the melting tank, wherein the passive batch material distributor is configured to evenly distributor batch material exiting the batch material feeder across a horizontal cross-section of the melting tank. The passive batch material distributor is removeable attached to the top of the melting tank. The passive batch material distributor comprises an upper support and a lower flapper section, wherein the upper support has a width wider than an interior diameter of the top side of the melting tank and the lower flapper section has a width narrower than the interior diameter of the top side of the melting tank, such that the upper support rests on top of the melting tank and the lower flapper section hangs at least partially down into the melting tank. The passive batch material distributor is configured to swing freely about a pivot point where the upper support meets the top side of the melting tank, and the passive batch material distributor is configured to swing freely when impacted by batch material falling from the passive batch material distributor into the melting tank and thereby distribute the batch material across the horizontal cross-section of the melting tank. In embodiments, the passive batch material distributor comprises a metal sheet and may comprise platinum.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic drawing of a cold crown induction glass melter system, according to embodiments of this disclosure.

[0013] Figure 2 is a schematic drawing of a cold crown induction glass melter system with in situ measuring, according to embodiments of this disclosure.

[0014] Figure 3 is a close-up view of the top of a cold crown induction melter system with a batch material distribution mechanism, according to embodiments.

[0015] Figure 4 is a schematic drawing of an example cold crown induction glass melter system, according to embodiments.

[0016] Figure 5 is a graph of temperature measurements over time using various temperature sensors, according to an example of embodiments.DETAILED DESCRIPTION

[0017] Various embodiments of the disclosure will be described in detail with reference to drawings, if any. Reference to various embodiments does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not limiting and merely set forth some of the many possible embodiments of the claimed invention.

[0018] Embodiments of this disclosure relate to systems and methods for cold crown melting of glass. Aspects of embodiments include all-electric cold crown melting systems using induction coils around a vertical melter design, where batch material is added uniformly from above the melt. Aspects of embodiments include a continuous cold crown melting system and process, wherein glass can be melted continuously by feeding batch material at the same rate that glass exits the downcomer of the melter. In addition, embodiments of this disclosure include melting tank designs with better spatial temperature control and improved in-situ measurement capabilities.

[0019] As used herein, “batch” or “batch material” refers to materials having compositional elements that, when melted together, form a desired glass composition. When melted, the batch material turns into a “glass melt,” “melt,” or “molten glass” within the melter. In the vertical design, the batch material is fed from the top and sits on top of the molten glass, and the molten glass in turn drops through a downcomer or outlet of the melter, after which point the glass cools and hardens. The batch, when sitting on top of the molten glass, may be described as forming a “batch blanket” that covers the molten glass. The batch blanket can help to reduce heat loss through the top of the melter from radiation of the molten glass surface. The crown space abovethe batch is not heated, making it a so-called “cold crown,” which also results in energy savings compared to hot crown melting.

[0020] Embodiments of this disclosure include new cold crown tank system designs and methods using the same, including process development methods, with significant advantages in process control and measurement. For example the cold crown induction tank is capable of repeated cooling and heating, unlike a refractory which would crack from thermal cycling. In addition, embodiments of this disclosure can be used with glasses that are incompatible with ceramic refractories. These aspects (e.g., being able to quickly cycle the system and take detailed measurements) make embodiments of this disclosure highly useful for R&D and / or process development of new and existing glass compositions, and better understanding of the batch reactions and quality of the resulting glass. Embodiments of this disclosure are not limited to use with particular glass compositions, and any glass compositions referred to herein are for illustrative or example purposes only. Indeed, the advantages of embodiments herein enable cold crown systems that can quickly be cycled on and off for melting a variety of different glass compositions without damaging the melter. While these advantages are clear for process development and R&D purposes, embodiments of this disclosure can also be used for larger scale glass production.

[0021] In embodiments, the cold crown melting tank and glass delivery downcomer are made of or lined with an inductive material and heated with induction. For example, in some embodiments, the cold crown melting tank and glass delivery downcomer are made of platinum or contain an inner platinum liner, although other materials that can be heated by induction can also be used. In aspects of embodiments, the upper cold section can be made of fused silica, quartz, or platinum. The above materials are listed for example only and are not intended to limit embodiments of this disclosure. A person of ordinary skill in the art could, based on this disclosure, choose suitable materials that meet the requirements of embodiments described herein.

[0022] Embodiments include a continuous melting system where the batch material is continuously fed from the top and heated from the sides and from the glass underneath. The advantage of the all-platinum or platinum liner design for the melting tank and downcomer is theability to add an additional heating zone in the upper batch melting section for additional thermal control of the batch reactions. This additional heating zone has advantages as some batches have a long temperature range for liquid formation and can cause a sintered batch bridge to form in the batch blanket without the additional thermal control afforded by the additional heating zone in the upper batch melting section. The downcomer includes yet another heating zone with separate thermal controls, and a thermocouple at the exit. The downcomer may feed into rollers or another suitable conveyance to draw the exiting glass. With multiple heating zones, the system is capable of finely controlled temperature gradients or temperature zones needed in different parts of the glass melting process. For example, a top heating zone in the area of the batch material or batch blanket, and possibly including the batch-melt interface, can be controlled independently of heating the glass melt below the batch-melt interface. The batch material, which does not necessarily conduct heat well, can require a lot of energy to heat up for melting. Even with high energy input, the batch material temperature raises slowly. However, applying the same high energy input to the melt below the batch blanket could have deleterious effects on the glass structure and composition, and can viscosity too low. On the other hand, a lower temperature zone below the melt and in the zone of the downcomer can be used to reduce the temperature of the molten glass to increase viscosity and control output of the glass.

[0023] With reference to Figure 1, an induction glass melting system 100 for producing glass is shown. The system 100 includes a melting tank 102 comprising an outer wall 103 extending vertically and configured to contain a batch material 112 for melting as well as molten glass or glass melt. The melting tank 102 has a top side 104 with an opening 105, and a bottom side 106 opposite the top side 104. The bottom side 106 may include a downcomer 128 that controls the descent of the glass melt and as it exits the melting tank 102 at an output 107 in the bottom side 106. To further assist in guiding and / or drawing glass out of the outlet 107, a ramp, guide, or rollers 129 can be used for glass 116 exiting the outlet 107. The system 100 also includes a batch material feeder 110 for feeding the batch material 112 from a batch source 114 to the melting tank 102 at the top side 104. The system also includes a multi-zone heating system with distinct zones 122a, 122b, 122c along the height / / of the melting tank 102 capable of controlled heating of each zone. The multi-zone heating system includes a plurality of induction coils 120a, 120b,120c wrapped around a periphery of the melting tank and configured to independently heat the plurality of heating zones 122a, 122b, 122c vertically along the height H of the melting tank. In this disclosure, “independently” refers to being able to separately control the energy output of each coil and / or temperature in each zone, which can include, for example, controlling power to the coils and timing of inducive heating.

[0024] The plurality of heating zones includes a batch material zone 122a that includes a vertical section long the height / / of the melting furnace 102 for housing the batch material 112 that has been added to the melting tank 102 by the batch material feeder 110. The batch material zone 122a may also include the batch-melt interface 143 (see Figure 2), which is where the batch material and the glass melt meet in the melting tank 102. The plurality of heating zones also includes a molten glass zone 122b that includes a vertical section long the height / / of the melting furnace 102 between the batch melt zone 122a and the glass melt outlet 107 where the molten glass is designed to be during the melt operation. The plurality of heating zones can also include a downcomer zone 122c disposed between the molten glass zone 122b and the glass melt outlet 107. In other words, in the vertical orientation of the glass melt system 100, the batch material zone 122a is at the top nearest the inlet of the bath material 112; the molten glass zone 122b is in the middle between the batch material zone 122a and the downcomer zone 122c; and the downcomer zone 122c is at the bottom nearest the outlet 107. Each of the plurality of heating zones 122a, 122b, 122c is capable of being individually heated using separate power inputs to each of the inductive coils 120a, 120b, 120c. Having individual control of heating in the batch material zone 122a allows a user to control the glass conversion rate of the batch material 112 more directly and precisely. By controlling the glass conversion rate to match the output rate of the glass 116 exiting the outlet 107, it is possible to have a continuous melting process using the cold crown melter system. For example, in examples of embodiments of this disclosure, glass production rate was controlled with temperature control of the downcomer zone 122c and the size of the tube through the downcomer 128 to achieve a glass output rate of 5-10 pounds / hour, for example. Then, by controlling the heating of the batch material zone 122a, the glass conversion rate could be matched to about 5-10 pounds / hour, resulting in a continuous induction melt process using the cold crown melting system. To achieve continuous feeding of the batchmaterial 112 to the melting tank 102, a feeding mechanism, such as a screw feeder or auger, can be used to push or pull batch material 112 from the batch source 114 to the melting tank 102. The batch material zone 122a temperature control also allows rapid melting of the batch and control of escape of evolved gases.

[0025] In aspects of embodiments, melting tank 102 is outfitted with a cold crucible 126 on the top side. The cold crucible 126 is not directly heated by any surrounding induction coils and those forms a cold zone 124 in the melting tank. The cold crucible 126 can function to help funnel batch material 112 into the melting tank 102 while helping to limit dust generation as the batch material 112 is fed into the melting tank 102. The cold crucible can be made of from many suitable materials, but some examples include fused silica, quartz, and platinum. In embodiments, the cold crucible may rest atop the opening of the melting tank 102, or may extend partially into the opening. Additional insulation can be used around the periphery of the cold crucible to reduce heat loss.

[0026] In order to inductively heat the plurality of heating zones 122a, 122b, 122c with the induction coils 120a, 120b, 120c, the wall 103 of the melting tank 102 and downcomer 128 can be made of an inductive material that heats up in response to the electromagnetic fields created by the induction coils. In some examples discussed herein, that material may be platinum, but other suitable materials are also contemplated. In embodiments, the wall 103 of the melting tank 102 and downcomer 128 need not be entirely made of the inductive material, but may only have an inner lining of the inductive material or have some component of inductive material sufficient to produce the required heat for the melt. In embodiments, the melting tank 102 using an inductive (e.g., platinum) liner inside a refractory sleeve.

[0027] With reference to Figures 1 and 3, feeding the batch material 112 to the melting tank 102 is aided by a batch feed tube 110 that carries batch material 112 from a batch source 114 to the opening 105 in the top side 104 of the melting tank 102. In embodiments, a screw feeder or other means (not shown) of moving the batch material may be used in conjunction with the batch feed tube 110. Without a means to evenly distribute the batch as it enters the top side 104 of the melting tank 102, batch material can pile up unevenly. Existing methods of evenly distributing the batch material can include complicated moving batch feed mechanisms, such as motorizedmechanisms to move the batch material feed in a circular or other pattern over the top of the melting tank. However, according to embodiments of this disclosure, a new batch material distribution mechanism can be used that does not require these complicated and expensive motorized mechanism. With reference to Figure 3, aspects of embodiments of this disclosure include a passive batch material distributor 150 disposed at the top side 104 of melting tank 102 between the batch material feeder 110 and the desired location of the batch blanket (e.g., batch material 142 in Figure 2) in the melting tank. The passive batch material distributor 150 is arranged to evenly distribute batch material 112 exiting the batch material feeder 110 across a width or horizontal cross-section of the melting tank to achieve a uniform batch blanket on top of the melt. In embodiments, the passive batch material distributor 150 includes an upper support 152 and a lower flapper section 154. The upper support 152 has a width wider than a width of the top of the melting tank 102 or cold crucible 126 on top of the melting tank, such that the upper support 152 can span across the opening at the top side of the system and the lower flapper section 154, with a width smaller than the width of the opening, can freely hang into the opening. In embodiments, the lower flapper section 154 may have a length such that the bottom of the lower flapper section extends only part way into the cold crucible 126. However, in embodiments, the passive batch material distributor 150 may also be long enough for the lower flapper section 154 to extend partially into the melting tank 102. The exact dimensions of the passive batch material distributor 150 may depend on the intended location of the batch blanket along the melting tank’s height H. In one illustrative example, a system according to embodiments of this disclosure may use a one-foot-tall quartz tube for the cold crucible sitting atop the melting tank, and the bottom of the passive batch material distributor 150 may be designed to be about one foot above the batch pile.

[0028] The passive batch material distributor 150 is “passive” because it does not require any motor or other means of applied external force to achieve even batch distribution, other than the force F of the batch material 112 itself impacting the passive batch material distributor 150. The impact of the batch material 112 on the passive batch material distributor 150 causes the passive batch material distributor 150 to swing, as shown by the directional arrows P in Figure 3, and the batch material 112 to be dispersed evenly. Free from the constraints of complicated motorized orother mechanisms, the passive batch material distributor 150 can be removably rested on top of the melter without any permanent attachment. Without permanent attachment, it is simple to remove the passive batch material distributor 150 if additional access to the top side opening is needed. Embodiments may also include means for attachment, permanently or removably, the passive batch material distributor 150 to the top side opening in a way that allows a bottom portion of the swing. In aspects of embodiments, the passive batch material distributor 150 can be constructed from a flat plate having rectangular features as shown in Figure 3. However, embodiments are not limited to the depiction in Figure 3, and can also include curved and / or rounded members, or other geometrical design, as well as plates or screen with opening to allow some of the batch material 112 to pass through the passive batch material distributor 150. In some example embodiments, the passive batch material distributor 150 is made of metal, such as platinum. In aspects of embodiments, the opening at the end of the batch material feeder 110 can be sized and shaped for additional control over the distribution of batch material 112 into the melting tank 102.

[0029] Because the batch material feeder 110 may include a tube that is angled down toward the opening 105 of the melting tank 102, it is possible for hot air and vapors to travel up the inside of the tube where it can eventually lead to the batch source 114. This can cause problems with temperature and condensation control of the batch material. To alleviate this issue, embodiments of this disclosure include a batch material feeder 110 with an opening 160 provided upstream but before the batch source 114, so that hot air and vapor can escape the batch material feeder 110 through the opening 160 before reaching the batch material, thus preventing temperature and condensation control issues.

[0030] According to embodiments of this disclosure, the induction melting furnace system is designed to take one or more in situ measurements during melting for improved process control. Referring to Figure 2, embodiments include a thermocouple 131 extending down the length of the melting tank 102. The thermocouple 131 is moveable in at least the vertical direction so that temperature can be measured all along the height of the system. In an aspect of embodiments, the thermocouple 131 is placed inside a thermocouple sheath 130, which can be a hollow tube with the hollow center being sized to allow the thermocouple to move within the sheath. In aspects ofembodiments, the thermocouple 131 and / or thermocouple sheath 130 are along the center line or center vertical axis 132 of the melting tank 102. The sheath 130 may be made of any material capable of withstanding the temperatures of the melter while allowing temperature readings to be taken by the thermocouple. For example, in some embodiments the sheath can be made of alumina. In embodiments, an additional hot spot thermocouple 136 is arranged at the hot spot 134 of the molten glass 144 to continuously monitor the high temperature there. The hot spot corresponds to the highest temperature of the molten glass during a continuous melting process. A bottom thermocouple 137 may be disposed at the bottom of the melting tank 102 where the molten glass enters the downcomer 128. Any type of heating sensor can be used that can adequately measure the temperature in these environments. In addition, embodiments can include optical pyrometers, such as a first pyrometer 138 below the hot spot, and a second pyrometer 139 at the bottom of the melting tank 102. As an additional aspect of embodiments, a contact thermocouple 140 can be used to directly measure the temperature of the glass 116 exiting the outlet 107.

[0031] According to embodiments of this disclosure, the continuous cold crown induction melter can be used without a finer or stirrer in the glass melt. The melt moves directly from the melting zone into the downcomer.

[0032] Examples

[0033] To test the induction cold crown melter according to embodiments of this disclosure, a prototype was built and tested with a variety of glass compositions. A schematic of the melter is shown in Figure 4. An inductively-heated platinum crucible and downcomer were chosen to allow the equipment to be quickly heated and cooled for day runs. The system has a 10-inch tall quartz cylinder as the cold crucible, which sits above and extends 3.5 inches into the platinum liner below. Below the quartz crucible the platinum liner in a refractory sleeve and the downcomer for melting cullet / batch and delivery of glass. The geometry of the downcomer can be adjusted to achieve a match between the outflow rate and the melt rate. For example, downcomers with diameters of 0.55 inches to 1 inch were used in experiments, with the 0.55 inch diameter being suitable for melt and outflow rate of 5-10 pounds per hour, in someexperiments. The downcomer was 20.5 inches long and was heated by induction heating as described above.

[0034] A comprehensive set of temperature measurements were used to track process variables. The earliest temperature measurement in the process was at the top of the batch blanket, which was tracked by IR camera and by handheld optical pyrometer. Temperatures in the batch blanket and glass were taken using a thermocouple inserted vertically in the center of the crucible, as shown in Figure 4. The thermocouple sheath in the melting crucible contained thermocouples in a movable alumina sheath. These thermocouples measured temperatures continuously at two different depths inside the crucible. In addition, the thermocouple was raised and lowered inside the alumina sheath to collect thermal profiles as a function of depth in the batch blanket and glass. A contact thermocouple was also added at the downcomer tip to measure glass delivery temperature, which helped for understanding viscosity change from crucible through downcomer to delivery.

[0035] Prior to starting continuous flow, the amount of time needed for the batch to melt conversion was meaured to determine if the melting rate was fast enough to provide stable continuous flow. At the beginning of the experiment, the platinum crucible was filled with molten glass to the desired batch / melt interface position. This interface was originally set at the top of the induction coils, but was later moved down 3 inches into the platinum crucible to provide additional heat to the sides of the batch blanket. The bottom 3 inches of the quartz crucible was wrapped with insulation. Batch was weighed and added by hand to the top of the melt surface. Enough batch was added to create a batch pile height of 2 inches-a typical weight for this amount of batch was 2.5 pounds for this sized system. Once the batch pile was built, photographs and thermal images were taken of the top surface of the melt to document changes to the appearance of the surface. These images were analyzed to quantify the decrease in batch area over time. If the batch melted too slowly, the temperature of the crucible was increased until the batch melted at a rate of about 5 pounds per hour. After the melting crucible temperature profile was established, the batch was added to the crucible continuously either by hand or with a screw feeder at the desired rate and the glass flow was started from the downcomer. The batch feed rate was calculated using a weight scale on the batch feeding system. The batch blanket position and thickness were also measured by inserting a quartz rod into the batch blanket and recording the height of the batch blanket and of the batch / glass interface. The amount of batchstuck to the quartz rod was then measured with reference to the quartz crucible lip, to track how much it changed over time. Batch surface temperatures were measured at regular intervals with a handheld optical pyrometer (emissivity set to 0.8). These measurements were taken at four equidistant points around the edge of the crucible surface and at the center approximately every 30 minutes. Temperatures were measured inside the batch blanket and glass using the internal thermocouple as described above. In addition to continuously collecting centerline thermocouple data, centerline profiles were also taken at every setpoint change, as well as every hour, allowing quantification of temperature as a function of depth through the crucible. Pyrometers were used to monitor the temperature of the outside of the platinum liner at its hottest location, and of the downcomer. The temperature of the glass exiting the downcomer tip was measured with a thermocouple. The instantaneous flow rate was calculated every 5 minutes from the weight of the glass strip collected in a bucket below the forming rollers.

[0036] Using this setup with a variety of glass compositions, high quality glass strips were produced. Control of the batch-to-glass conversion through the appropriate choice of temperature, temperature gradient, feed rate and pull rate were used to effectively control the continuous process. The resulting glass was found to have good quality and resolved issues around retention of additives to the glass composition and prevention of these additives forming solid defects in the glass. Solid defects were rate in the resulting glass.

[0037] Figure 5 shows a plot of temperature measurements over time taken at the crucible hot spot, the centerline, the crucible, the downcomer, and the glass delivery or outlet. The centerline thermocouple was raised up towards the batch pile and then back down to measure temperature as a function of vertical position on a regular basis, as shown by the slightly vertical thermal profiles. Overall, the temperatures were very stable. Figure 5 is provided as an example of one experimental run for illustrative purposes to show the in situ measurement capabilities of embodiments of this disclosure.

[0038] Experimental examples have shown that the continuous cold crown melter according to embodiments of this disclosure is cable of delivering a controlled and managed process.

[0039] Illustrative Implementations

[0040] The following is a description of various aspects of implementations of the disclosed subject matter. Each aspect may include one or more of the various features, characteristics, or advantages of the disclosed subject matter. The implementations are intended to illustrate a few aspects of the disclosed subject matter and should not be considered a comprehensive or exhaustive description of all possible implementations.

[0041] Aspect 1 pertains to an induction glass melting system for producing glass comprising: a melting tank comprising an outer wall extending vertically and configured to contain a batch material for melting and molten glass, the melting tank comprising a top side and a bottom side opposite the top side; a batch material feeder for feeding the batch material to the melting tank at the top side; a glass melt outlet for discharging a glass melt resulting from melting the batch material in the melting tank, the glass melt outlet being configured to discharge the glass melt at the bottom side; and a multi-zone heating system comprising a plurality of induction coils around a periphery of the melting tank and configured to independently heat a plurality of heating zones vertically along a height of the melting tank.

[0042] Aspect 2 pertains to the induction glass melting system of Aspect 1, wherein the plurality of heating zones comprises a batch material zone.

[0043] Aspect 3 pertains to the induction glass melting system of Aspect 2, wherein the batch material zone comprises a section along the height of the melting furnace configured for housing the batch material added to the melting tank by the batch material feeder.

[0044] Aspect 4 pertains to the induction glass melting system of Aspect 2 or Aspect 3, wherein the batch material zone comprises a section along the height of the melting furnace at which an interface between the batch material and the molten glass is designed to be disposed.

[0045] Aspect 5 pertains to the induction glass melting system of any of Aspects 2-4, wherein the plurality of heating zones comprises a molten glass zone disposed between the batch material zone and the glass melt outlet.

[0046] Aspect 6 pertains to the induction glass melting system of Aspect 5, wherein the molten glass zone comprises a section along the height of the melting furnace configured for housing the molten glass.

[0047] Aspect 7 pertains to the induction glass melting system of any of Aspects 5 or 6, wherein the plurality of heating zones comprises a downcomer zone disposed between the molten glass zone and the glass melt outlet.

[0048] Aspect 8 pertains to the induction glass melting system of Aspect 1, wherein the plurality of heating zones comprises a batch material zone, a molten glass zone, and a downcomer zone, wherein the batch material zone is disposed vertically above the molten glass zone, the downcomer zone is disposed vertically below the molten glass zone, and the molten glass zone is disposed vertically between the batch material zone and the downcomer zone.

[0049] Aspect 9 pertains to the induction glass melting system of any of Aspects 1-8, wherein the outer wall of the melting furnace comprises an inductive wall material configured to be inductively heated by the multi-zone heating system, and the inductive wall material is configured to heat the batch material and / or the molten glass inside the melting tank.

[0050] Aspect 10 pertains to the induction glass melting system of Aspect 9, the outer wall comprises an inner liner comprising the inductive wall material.

[0051] Aspect 11 pertains to the induction glass melting system of Aspect 9 or 10, wherein the inductive wall material comprises platinum.

[0052] Aspect 12 pertains to the induction glass melting system of any of Aspects 1-11, wherein the melting furnace comprises an upper cold zone above the batch material zone, wherein the upper cold zone is not directly heated by a heating element in or surrounding the upper cold zone.

[0053] Aspect 13 pertains to the induction glass melting system of Aspect 12, wherein the upper cold zone comprises a crucible comprising fused silica, quartz, or platinum.

[0054] Aspect 14 pertains to the induction glass melting system of any of Aspects 1-13, wherein the induction melting furnace system is configured to be a continuously fed with batch material.

[0055] Aspect 15 pertains to the induction glass melting system of any of Aspects 1-14, further comprising a thermocouple configured to measure a temperature of at least one of the batch material and the molten glass within the glass furnace.

[0056] Aspect 16 pertains to the induction glass melting system of Aspect 15, further comprising a thermocouple sheath disposed at least partially within the melting tank and extending in a direction parallel to the vertical length of the melting tank, the thermocouple sheath comprising a hollow tube sized to fit the thermocouple within the hollow tube.

[0057] Aspect 17 pertains to the induction glass melting system of Aspect 16, wherein the thermocouple is configured to move within the hollow tube to temperature readings at different heights within the melting tank.

[0058] Aspect 18 pertains to the induction glass melting system of Aspect 16 or 17, wherein the thermocouple sheath is configured to move vertically within the melting tank.

[0059] Aspect 19 pertains to the induction glass melting system of any of Aspects 16-18, wherein the thermocouple sheath comprises alumina.

[0060] Aspect 20 pertains to the induction glass melting system of any of Aspects 1-19, further comprising a hot spot thermocouple disposed at a vertical position of the melting tanks that corresponds to highest temperature of the molten glass during a continuous melting process.

[0061] Aspect 21 pertains to the induction glass melting system of Aspect 20, wherein the hot spot thermocouple is stationary.

[0062] Aspect 22 pertains to the induction glass melting system of any of Aspects 1-21, further comprising one or more temperature sensors.

[0063] Aspect 23 pertains to the induction glass melting system of Aspect 22, wherein the one or more temperature sensors are disposed at at least one of the hot spot, the bottom of the molten glass zone, and the bottom of the downcomer zone where glass exits the downcomer.

[0064] Aspect 24 pertains to the induction glass melting system of any of Aspects 1-23, wherein the batch material feeder comprises a batch feed tube comprising an outlet arranged near the top of the melting tank and an opening upstream of the outlet, wherein the opening is configured to allow heat emanating from the melting tank and / or vapor to escape from the batch feed tube before reaching a source of the batch material.

[0065] Aspect 25 pertains to the induction glass melting system of any of Aspects 1-24, further comprising a passive batch material distributor disposed between the batch material feeder and the melting tank, wherein the passive batch material distributor is configured toevenly distributor batch material exiting the batch material feeder across a horizontal crosssection of the melting tank.

[0066] Aspect 26 pertains to the induction glass melting system of Aspect 25, wherein the passive batch material distributor is removeable attached to the top of the melting tank.

[0067] Aspect 27 pertains to the induction glass melting system of Aspect 25 or 26, wherein the passive batch material distributor comprises an upper support and a lower flapper section, wherein the upper support has a width wider than an interior diameter of the top side of the melting tank and the lower flapper section has a width narrower than the interior diameter of the top side of the melting tank, such that the upper support rests on top of the melting tank and the lower flapper section hangs at least partially down into the melting tank.

[0068] Aspect 28 pertains to the induction glass melting system of Aspect 27, wherein the passive batch material distributor is configured to swing freely about a pivot point where the upper support meets the top side of the melting tank, and wherein the passive batch material distributor is configured to swing freely when impacted by batch material falling from the passive batch material distributor into the melting tank and thereby distribute the batch material across the horizontal cross-section of the melting tank.

[0069] Aspect 29 pertains to the induction glass melting system of any one of Aspects 25-28, wherein the passive batch material distributor comprises a metal sheet.

[0070] Aspect 30 pertains to the induction glass melting system of Aspect 29, wherein the passive batch material distributor comprises platinum.Definitions

[0071] ‘ ‘Include,” “includes,” or like terms means encompassing but not limited to, that is, inclusive and not exclusive.

[0072] ‘ ‘About” modifying, for example, the quantity of an ingredient in a composition, concentrations, volumes, process temperature, process time, yields, flow rates, pressures, viscosities, and like values, and ranges thereof, or a dimension of a component, and like values, and ranges thereof, employed in describing the embodiments of the disclosure, refers to variation in the numerical quantity that can occur, for example: through typical measuring and handlingprocedures used for preparing materials, compositions, composites, concentrates, component parts, articles of manufacture, or use formulations; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of starting materials or ingredients used to carry out the methods; and like considerations. The term “about” also encompasses amounts that differ due to aging of a composition or formulation with a particular initial concentration or mixture, and amounts that differ due to mixing or processing a composition or formulation with a particular initial concentration or mixture.

[0073] “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0074] The indefinite article “a” or “an” and its corresponding definite article “the” as used herein means at least one, or one or more, unless specified otherwise.

[0075] Abbreviations, which are well known to one of ordinary skill in the art, may be used (e.g., “h” or “hrs” for hour or hours, “g” or “gm” for gram(s), “mL” for milliliters, and “rt” for room temperature, “nm” for nanometers, and like abbreviations).

[0076] Specific and preferred values disclosed for components, ingredients, additives, dimensions, conditions, and like aspects, and ranges thereof, are for illustration only; they do not exclude other defined values or other values within defined ranges. The systems, kits, and methods of the disclosure can include any value or any combination of the values, specific values, more specific values, and preferred values described herein, including explicit or implicit intermediate values and ranges.

[0077] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred.

[0078] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodimentsincorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.

[0079] The foregoing description of the present disclosure is provided as an enabling teaching thereof and its best, currently-known embodiment. Those skilled in the art will recognize that many changes can be made to the embodiments described herein while still obtaining the beneficial results of the present disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations of the present disclosure are possible and may even be desirable in certain circumstances and are part of the present disclosure. Thus, the foregoing description is provided as illustrative of the principles of the present disclosure and not in limitation thereof.

[0080] Those skilled in the art will appreciate that many modifications to the exemplary embodiments described herein are possible without departing from the spirit and scope of the present disclosure. Thus, the description is not intended and should not be construed to be limited to the examples given but should be granted the full breadth of protection afforded by the appended claims and equivalents thereto. In addition, it is possible to use some of the features of the present disclosure without the corresponding use of other features. Accordingly, the foregoing description of exemplary or illustrative embodiments is provided for the purpose of illustrating the principles of the present disclosure and not in limitation thereof and may include modification thereto and permutations thereof.

[0081] In the foregoing description, like reference characters designate like or corresponding parts throughout the several views shown in the figures. It is also understood that, unless otherwise specified, terms such as “top,” “bottom,” “outward,” “inward,” and the like are words of convenience and are not to be construed as limiting terms. In addition, whenever a group is described as comprising at least one of a group of elements and combinations thereof, it is understood that the group may comprise, consist essentially of, or consist of any number of those elements recited, either individually or in combination with each other.

[0082] Similarly, whenever a group is described as consisting of at least one of a group of elements or combinations thereof, it is understood that the group may consist of any number of those elements recited, either individually or in combination with each other. Unless otherwise specified, a range of values, when recited, includes both the upper and lower limits of the range. As used herein, the indefinite articles “a,” and “an,” and the corresponding definite article “the” mean “at least one” or “one or more,” unless otherwise specified.

[0083] While this description may include many specifics, these should not be construed as limitations on the scope thereof, but rather as descriptions of features that may be specific to particular embodiments. Certain features that have been heretofore described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and may even be initially claimed as such, one or more features from a claimed combination may in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a sub-combination.

[0084] Similarly, while operations are depicted in the drawings or figures in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous

[0085] Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, examples include 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 aspect. 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.

[0086] It is also noted that recitations herein refer to a component of the present disclosure being “configured” or “adapted to” function in a particular way. In this respect, such acomponent is “configured” or “adapted to” embody a particular property, or function in a particular manner, where such recitations are structural recitations as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “configured” or “adapted to” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.

[0087] While preferred embodiments of the present disclosure have been described, it is to be understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalence, many variations and modifications naturally occurring to those of skill in the art from a perusal hereof.

Claims

CLAIMSWhat is claimed:

1. An induction glass melting system for producing glass comprising: a melting tank comprising an outer wall extending vertically and configured to contain a batch material for melting and molten glass, the melting tank comprising a top side and a bottom side opposite the top side; a batch material feeder for feeding the batch material to the melting tank at the top side; a glass melt outlet for discharging a glass melt resulting from melting the batch material in the melting tank, the glass melt outlet being configured to discharge the glass melt at the bottom side; and a multi-zone heating system comprising a plurality of induction coils around a periphery of the melting tank and configured to independently heat a plurality of heating zones vertically along a height of the melting tank.

2. The induction glass melting system of claim 1 , wherein the plurality of heating zones comprises a batch material zone.

3. The induction melting furnace system of claim 2, wherein the batch material zone comprises a section along the height of the melting furnace configured for housing the batch material added to the melting tank by the batch material feeder.

4. The induction melting furnace system of claim 2 or claim 3, wherein the batch material zone comprises a section along the height of the melting furnace at which an interface between the batch material and the molten glass is designed to be disposed.

5. The induction melting furnace system of any of claims 2-4, wherein the plurality of heating zones comprises a molten glass zone disposed between the batch material zone and the glass melt outlet.

6. The induction melting furnace system of claim 5, wherein the molten glass zone comprises a section along the height of the melting furnace configured for housing the molten glass.

7. The induction melting furnace system of any of claims 5 and 6, wherein the plurality of heating zones comprises a downcomer zone disposed between the molten glass zone and the glass melt outlet.

8. The induction melting furnace system of claim 1, wherein the plurality of heating zones comprises a batch material zone, a molten glass zone, and a downcomer zone, wherein the batch material zone is disposed vertically above the molten glass zone, the downcomer zone is disposed vertically below the molten glass zone, and the molten glass zone is disposed vertically between the batch material zone and the downcomer zone.

9. The induction melting furnace system of any of claims 1-8, wherein the outer wall of the melting furnace comprises an inductive wall material configured to be inductively heated by the multi-zone heating system, and the inductive wall material is configured to heat the batch material and / or the molten glass inside the melting tank.

10. The induction melting furnace of claim 9, the outer wall comprises an inner liner comprising the inductive wall material.

11. The induction melting furnace system of claim 9 or claim 10, wherein the inductive wall material comprises platinum.

12. The induction melting furnace system of any of claim 1-11, wherein the melting furnace comprises an upper cold zone above the batch material zone, wherein the upper cold zone is not directly heated by a heating element in or surrounding the upper cold zone.

13. The induction melting furnace system of claim 12, wherein the upper cold zone comprises a crucible comprising fused silica, quartz, or platinum.

14. The induction melting furnace system of any of claims 1-13, wherein the induction melting furnace system is configured to be a continuously fed with batch material.

15. The induction melting furnace system of any of claims 1-14, further comprising a thermocouple configured to measure a temperature of at least one of the batch material and the molten glass within the glass furnace.

16. The induction melting furnace system of claim 15, further comprising a thermocouple sheath disposed at least partially within the melting tank and extending in a direction parallel to the vertical length of the melting tank, the thermocouple sheath comprising a hollow tube sized to fit the thermocouple within the hollow tube.

17. The induction melting furnace system of claim 16, wherein the thermocouple is configured to move within the hollow tube to temperature readings at different heights within the melting tank.

18. The induction melting furnace system of claim 16 or claim 17, wherein the thermocouple sheath is configured to move vertically within the melting tank.

19. The induction melting furnace system of any of claims 16-18, wherein the thermocouple sheath comprises alumina.

20. The induction melting furnace system of any of claims 1-19, further comprising a hot spot thermocouple disposed at a vertical position of the melting tanks that corresponds to highest temperature of the molten glass during a continuous melting process.

21. The induction melting furnace system of claim 20, wherein the hot spot thermocouple is stationary.

22. The induction melting furnace system of any of claims 1-21, further comprising one or more temperature sensors.

23. The induction melting furnace system of claim 22, wherein the one or more temperature sensors are disposed at at least one of the hot spot, the bottom of the molten glass zone, and the bottom of the downcomer zone where glass exits the downcomer.

24. The induction melting furnace system of any of claims 1-23, wherein the batch material feeder comprises a batch feed tube comprising an outlet arranged near the top of the melting tank and an opening upstream of the outlet, wherein the opening is configured to allow heat emanating from the melting tank and / or vapor to escape from the batch feed tube before reaching a source of the batch material.

25. The induction melting furnace system of any of claims 1-24, further comprising a passive batch material distributor disposed between the batch material feeder and the melting tank, wherein the passive batch material distributor is configured to evenly distributor batch material exiting the batch material feeder across a horizontal cross-section of the melting tank.

26. The induction melting furnace system of claim 25, wherein the passive batch material distributor is removeable attached to the top of the melting tank.

27. The induction melting furnace system of claim 25 or claim 26, wherein the passive batch material distributor comprises an upper support and a lower flapper section, wherein the upper support has a width wider than an interior diameter of the top side of the melting tank and the lower flapper section has a width narrower than the interior diameter of the top side of themelting tank, such that the upper support rests on top of the melting tank and the lower flapper section hangs at least partially down into the melting tank.

28. The induction melting furnace system of claim 27, wherein the passive batch material distributor is configured to swing freely about a pivot point where the upper support meets the top side of the melting tank, and wherein the passive batch material distributor is configured to swing freely when impacted by batch material falling from the passive batch material distributor into the melting tank and thereby distribute the batch material across the horizontal cross-section of the melting tank.

29. The induction melting furnace system of any of claims 25-28, wherein the passive batch material distributor comprises a metal sheet.

30. The induction melting furnace system of claim 29, wherein the passive batch material distributor comprises platinum.

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